How to Prepare For a Placement Test Essay

How to Prepare For a Placement Test EssayMost people are under the impression that placement test essays samples are just meant for students. But there are some individuals who need help preparing for a different kind of test - the placement test.Many colleges and universities have small skill gaps in their class. Students often try to fill these skill gaps with an essay sample. But students should be aware that there are many people who also need this help.Many major corporations have individual test formats, such as an essay or interview. There are even writing samples for multiple choice questions for these types of exams. You might be surprised to know that these companies also make use of placement test essays. In fact, if you look at the small print, many of these companies do require you to write an essay, no matter how simple it is.There are many companies that provide placement test samples for writers. The companies not only offer the writing samples but also their evaluati on methods. Some companies may require a website or blog post on the topic or an essay, and others may only ask for one or two writings.The thing to keep in mind is that the essays should be unique and must speak about what the applicant has actually done or what he has been taught in the course. If you would like to gain admission to some of the top business schools in the country, it is important that you write your own essays.Some of the places where students can find these test essay samples are not difficult to find. The internet is a good place to look for websites. You can also contact the admissions department at the school you want to apply to.One of the keys to writing a good essay is to get familiar with the topics you will be writing about. A good strategy is to base your essay on a real life experience.If you want to submit a sample of your writing, make sure to read the test requirements and the requirements for the company before you submit any samples. Good luck with your application! Good luck!

Education Is The Most Powerful Weapon - 868 Words

Nelson Mandela one said, â€Å"Education is the most powerful weapon we can use to change the world.† Education is not just a term to explain a process of getting instructions. Instead, education is extremely essential procedure in one’s life to have this weapon as explained by Mandela. As individuals we tend to learn from life experiences and events that go on around us. We not only learn about how to become successful in life instead we learn how to make a living as we encounter new individuals and new life lessons that teach us whether how to cook, clean, or even how to do math. A person cannot only be educated if they have a degree instead we all are educated in some unique manner whether it is to sew, draw, sing, or even as a doctor which helps us complete our given task. School is an institution created to discipline and educate students in order to become more knowledgeable. Many individuals in history and even people now attend school as it has become a crucial part in our society just like how other places such as hospitals and stores have in order to meet the needs of the society’s members. Many individuals believe that school is not an essential aspect in life that helps one grow because of how they are being educated, in which John Gatto is one of them as well. Even though no school is the best for everyone, it is still needed to help an individual grow emotionally, intellectual, and socially into a contributing member of society. Gatto is the author of the article,Show MoreRelatedEducation Is The Most Powerful Weapon Essay1252 Words   |  6 PagesThroughout our history, most of the revolutions were turning points that contributed and improved the modern society that we are living now. Social reformers such as Benjamin Franklin and Thomas Jefferson have been spreading the message that education is crucial in leading to a successful life. However, there are still many people, especially those from the bottom of our social hierarchy pyramid, are struggling in daily life because of the lack of education. Social problems that we encounter theseRead MoreEducation Is The Most Powerful Weapon1841 Words   |  8 Pagesâ€Å"Education is the most powerful weapon which you can use to change the world†, says former South African President, Nelson Mandela. While this statement is very true, there are a few caveats to this statement. If students do not want to reap all the benefits of education, they will not be as likely to change the world. Therefore, we need to make sure to provide an education that facilitates change in the world. One way of doing this is improving the quality of instruction to facilitate learningRead MoreEducation Is The Most Powerful Weapon878 Words   |  4 PagesEducation has been aimed at helping students learn new and exciting things every day, that later they can use in their own lives. A purpose in education is to teach students developmental skills in; math, reading, language arts, and science. This helps us gain practice, patience, and skills for job preparation, college, and social and moral responsibility for ourselves. During my senior year of high school, all of my teachers were preparing us for college. They prepared us by having us write papersRead MoreEducation Is The Most Powerful Weapon1343 Words   |  6 PagesKnowledge. Education. These are the most powerful weapon in life, and since the dawn of time knowledge becomes the ultimate skill of an in dividual. Through the blade of knowledge, we can unleash our true full potential, eventually contributing massively to the world in exactly the same way great minds have done. Leaving behind countless contributions is the mark of a truly successful person. According to Nelson Mandela, the celebrated former President of South Africa, â€Å"Education is the most powerful weaponRead MoreEducation Is The Most Powerful Weapon1541 Words   |  7 PagesNelson Mandela said, â€Å"Education is the most powerful weapon which you can use to change the world.† Miriam-Webster dictionary defines education as the knowledge, skill, and understanding that you get from attending a school, college, or university. In today’s society, education is dispensed and received through different forms: campus-based, internet-based, distance, and home education. Home education or homeschool means a nonpublic school conducted primarily by the parent, guardian or other personRead MoreEducation Is T he Most Powerful Weapon2016 Words   |  9 Pages Nelson Mandela said, ?Education is the most powerful weapon which you can use to change the world?. If one were to think introspect on the quote, one can realize the value of education. Education is not only needed for the betterment of any nation but the whole human kind. It is because of education that humans are achieving milestones such leading on the moon and exploring other planets such as Mars. When one is educated, their education gives them endless opportunityRead MoreEducation Is The Most Powerful Weapon1195 Words   |  5 Pagessaid â€Å"Education is the most powerful weapon which you can use to change the world,† and this should be our guiding principle when instituting reform in our country. The United States has the worst economic inequality in the developed world. The wealthy are making more money than ever and the amount of people living in poverty are growing at an alarming rate. As a whole, the impoverished are struggling to provide for their basic needs. A major factor in this inequality is the gap in education. InnerRead MoreEducation I s The Most Powerful Weapon Essay815 Words   |  4 Pages PSC 443 Nelson Mandela said, â€Å"Education is the most powerful weapon which you can use to change the world.† (â€Å"Top 10 Education Quotes) Education is a highly debated topic and many countries are in constant competition to be on top. Two countries who focus heavily on education are Japan and Germany. These two countries differ in a multitude of ways as to how they choose to educate their youth. In Germany, children age three to six can attend pre-school, however, pre-school is not freeRead MoreEducation Is The Most Powerful Weapon1373 Words   |  6 Pagesâ€Å"Education is the most powerful weapon we can use to change the world† (Nelson Mandela). United States. has a powerful educational arsenal, its community colleges. For the reason being, community college should be free for students of less fortunate and other students who cannot afford college after high school. If the government proposed free community college to the students, each and everyone will have the chance to get an education as well the opportunity to have a better future. Free communityRead MoreEducation Is The Most Powerful Weapon1598 Words   |  7 PagesIntroduction Education, the most powerful weapon which can be used to change the world. Miriam-Webster dictionary defines education as the knowledge, skill, and understanding that you get from attending a school, college, or university (1). In today’s society, education is dispensed and received through different forms: campus-based, internet-based, distance, and home education. Home education or homeschool means a nonpublic school conducted primarily by the parent, guardian or other person having

Gmat Argumentative Essay Samples

<h1>Gmat Argumentative Essay Samples</h1><p>Gmat contentious exposition tests are an extraordinary method to begin recorded as a hard copy your first pugnacious article. Regardless of whether you are a first-time author or an accomplished one, you can discover these papers online at no cost.</p><p></p><p>Arguments utilized in exposition composing may contrast starting with one individual then onto the next. On the off chance that you are going to utilize various contentions from various journalists, you need to ensure that you apply similar principles in each section. You can't be one of the author's aides in the event that you are not cautious in the manner you compose your essay.</p><p></p><p>Gmat article tests can help you in the whole procedure of composing an elegantly composed exposition. With the correct article themes, you won't have to do anything besides simply follow the rules for a brief timeframe. Regardle ss of whether you are an awesome essayist, it is highly unlikely that you can make an impeccable contention in a limited ability to focus time. That is the reason you ought to figure out how to recognize the key components in each argument.</p><p></p><p>Essay composing is likewise founded on the various components that show up in each passage. For instance, you might need to recognize the sections containing the two subtleties and contentions. For this situation, you need to consider whether you need to make a particular contention or attempt to persuade others in general.</p><p></p><p>You must comprehend what to do in this circumstance. In the event that you need to recognize nitty gritty and influential contentions, you ought to consider the accompanying rules:</p><p></p><p>Question and Answer - The inquiry is the fundamental piece of a passage. The primary target of an exposition is to respond to the inquiry, so it is savvy to begin your passage with an inquiry. On the off chance that you truly need to persuade individuals to think about your feeling, you ought to pose inquiries that lead to an end. In the event that you would prefer not to persuade others by basically responding to their inquiries, you can in any case express your point.</p><p></p><p>However, on the off chance that you need to communicate your point in a solitary sentence, you need to end your passage with an inquiry. You can have a subsequent inquiry in the event that you wish to clarify further.</p><p></p><p>Discussion and Conclusion - After responding to the inquiry, you have to make an end. It is dependent upon you to choose what you are going to discuss in the finish of your passage. This is your opportunity to demonstrate your point. In the event that you truly need to persuade perusers, you need to ensure that you finish your section with a solid argument.</p> ;

Good Topics For Archivel Research Paper During the Civil War

<h1>Good Topics For Archivel Research Paper During the Civil War</h1><p>You must be comfortable with the time and time of our country's history when its kin were the 'Confederates'. Some of you may have just considered doing this exploration paper and you can discover hundreds if not a great many various subjects to consider. Be that as it may, in the event that you are capable, there are acceptable themes for documented research paper during the Civil War.</p><p></p><p>To start, there are the valiant men who battled to secure the privilege of a free people. It is acceptable to remember that the very establishments of our country were based upon those standards. At that point there are the ladies and youngsters who were lost in the battle to save this wonderful nation. A definitive penances were made by such huge numbers of valiant people, yet they were here and there considerably more than any others since it included everything from African Americans to Native Americans.</p><p></p><p>Every single one of us, paying little mind to race, religion, statement of faith, or sexual orientation, ought to be glad to remain before the Civil War and talk about how we can recollect them today. From the African Americans to the poor rustic American, each and every individual who was included was exceptional. In this day and age, we should recall that even today, we are for the most part equivalent. We live in an extraordinary nation, and we have the chance to make it even better.</p><p></p><p>In the present world, we may feel that we can't successfully improve this a spot, however perhaps we have to recall the Civil War and how it affected our country's history. Everybody merits regard. It is acceptable to remember that we are as yet battling wars against a similar trouble makers, however we may figure out how to cooperate. This can incorporate one another, or it might be each country working together.</p><p></p><p>There are no terrible things to be said about the Civil War, yet we have to make a stride back and understand that there were a few parts of the war that we may have neglected. Maybe we will think about perusing the news, getting a history book, or finding different assets on the subject. You will discover many intriguing books regarding the matter that can assist you with becoming familiar with the past.</p><p></p><p>Even however you would prefer not to cause an excessive amount to notice these subjects during the Civil War, it is as yet essential to recollect what they mean for our future. Perhaps you will discover some motivation through one of these points for authentic research paper during the Civil War. At that point you should simply pass them down to your own children.</p><p></p><p>So it's just as simple as that the Civil War. That is the reason today is the day to compos e your own paper. Ensure that it is a theme that can be advantageous to your kids, grandkids, or other history understudy. In the event that you are uncertain of how to begin, you can talk with a curator at your neighborhood library.</p>

History Essay Sample - What to Consider Before You Choose the Right Course

<h1>History Essay Sample - What to Consider Before You Choose the Right Course</h1><p>A history paper test is a course task that will support you and your understudies in planning for the last, graduate degree test. This example is regularly joined by an A-Z prospectus that portrays the structure of this sort obviously. While the understudy gets a handbook with the entirety of the data required for planning for the end of the year test, a great and proficient article might be missing from the course material.</p><p></p><p>The first activity is to counsel a book that is useful on the investigation of local American ladies. A few sites contain these assets which makes it simple for the understudies to peruse and discover the assets they need. It will likewise give them a thought on what sort of realizing style to utilize when composing the essay.</p><p></p><p>On the other hand, there are numerous misguided judgments that are as yet being sustained in individuals' psyche. These fantasies for the most part include the job of ladies in beginning of human advancement. These individuals may consider ladies to be in effect young ladies or even ladies who were essentially workers. Actually, these observations are not all that and numerous reports and confirmations assist us with understanding the genuine jobs of ladies at that time.</p><p></p><p>There are two assessments that are bound to get individuals to accept that Native American ladies are totally reliant on men. One is that ladies are slaves who give housekeeping, cooking, childcare, and sewing for their spouses. The other one is that men accept all the obligations of housekeeping, cooking, childcare, and sewing. Both of these perspectives are not extremely sensible, as it isn't feasible for ladies to be autonomous in those times.</p><p></p><p>Even back then, the work and work performed by Native Amer ican ladies are critical. These errands are referred to most history specialists as the 'behind the factory' employments which got significant during the occupationof settlement.</p><p></p><p>Women assumed a huge job in open occasions. It has been demonstrated that ladies were the essential possibility to pick the administration positions during times when ladies were not permitted to become pioneers. Ladies for the most part drove their gatherings during the timeframe when most conventional culture is beginning to decay and ladies felt the weight of initiative roles.</p><p></p><p>The investigation of history is the investigation of past circumstances and individuals' activities during those occasions and in those spots. They utilized these confirmations to portray those periods and situations.</p><p></p><p>A great history exposition test will be exceptionally useful for you. These examples ought to incorporate everything that you have to think about the current subject. You can utilize this example in your homeroom to get ready for the last exam.</p>

What You Need to Know About GRE Issue Essay Sample Topics

<h1>What You Need to Know About GRE Issue Essay Sample Topics</h1><p>GRE issue article test subjects can be the perfect answer for any of your exposition composing issues. It isn't that hard to compose a critical thinking exposition. You simply need to realize what inquiries to pose and how to do it. Likewise with numerous different parts of composing, you have to utilize the correct article writer.</p><p></p><p>If you are not extremely competent at utilizing the product programs accessible to assist you with this, at that point it is a good thought to employ an expert author to do it for you. There are numerous individuals who like to do it all alone. Nonetheless, in the event that you need to get familiar with how to structure a paper, at that point a prepared proficient will be the privilege choice.</p><p></p><p>GRE issue exposition test subjects will assist you with figuring out how to utilize the product program a ccessible to support you. It will show you how to design the inquiries appropriately with the goal that they are in the correct configuration and can be utilized appropriately by the product. You ought to likewise figure out how to assemble a sentence or section that can respond to every one of the inquiry correctly.</p><p></p><p>It is an extremely simple undertaking to follow the headings. Most authors that utilization this kind of programming bundle will assemble an exposition for you. They will check for sentence structure and spelling mistakes. On the off chance that they discover any blunders, at that point they won't permit you to proceed the work.</p><p></p><p>The educator will likewise see whether you are understanding the directions well. On the off chance that you are experiencing difficulty getting it, you won't express what is on your mind. This is the reason it is ideal to have another person with you when you utilize the product to assist you with getting the paper written.</p><p></p><p>They will see whether you are attempting to discover alternate routes to finding the solutions to your inquiries. There are numerous who do this. They don't get the task wrapped up. Since there are just a not many that are great, you would prefer not to depend on alternate routes that won't offer you the responses that you want.</p><p></p><p>The last thing you need to discover before you begin to chip away at your paper is that you will do the task the correct way. You can discover how to compose a brilliant paper without utilizing programming by looking at a portion of the GRE issue article test points online.</p>

Eighth Grade Research Paper Topics - An Idea That Might Just Turn Out To Be Profitable For You

<h1>Eighth Grade Research Paper Topics - An Idea That Might Just Turn Out To Be Profitable For You</h1><p>Here are some eighth grade investigate paper themes that will truly be a resource for you. They are fun, fascinating and can fill in as the reason for an intriguing class venture. We should get started.</p><p></p><p>Ask your children to think about an issue or a most loved story they've found out about in school science labs. In the event that there is a specialist regarding the matter, request that they give you a short bio. You can even ask another person to support you. This is an incredible spot to begin as this will permit you to bounce directly into the inquiries at hand.</p><p></p><p>Next, discover what researchers and specialists consider the ebb and flow political atmosphere. Ask them what issues they're confronting and what they figure arrangements may be.</p><p></p><p>Once you hav e this data, get a few papers or short reports. Make a rundown of all the ongoing stories and occasions. Whenever you visit your library, investigate the news to check whether there is anything on issues the children are included in.</p><p></p><p>Then, feel free to build up the logical and research questions. Normally, one of the main inquiries you'll be posed is what is a radiation portion? Feel free to be as explicit as possible.</p><p></p><p>The next inquiry you ought to have the option to create a speculation and test them. Since you have the essential logical data, you would then be able to dive into the subtleties. The more you think about a specific issue, the better you'll have the option to concoct answers.</p><p></p><p>As you can see, these eighth grade examine paper subjects are an extraordinary method to investigate regions that you've been finding out about in the study hall. The majority of these t hemes are likewise open finished enough that you can utilize different wellsprings of data to assist you with your research.</p>

MMLA For Research Papers

<h1>MMLA For Research Papers</h1><p>More regularly than not, understudies normally search for a decent MMLA style for look into papers. MMLA style is useful for the specialist as it gives them a thought on the best way to dispose of all the paper for simple reference. However, it very well may be smarter to comprehend that there are two sorts of paper; one being the overwhelming paper and the other the light one. So what is an 'overwhelming' paper?</p><p></p><p>These papers are called substantial in light of the fact that it is intended for inquire about reason and not for regular use. As a rule, it is long and the paper is in acceptable request. It additionally must be very much created and organized.</p><p></p><p>A MMLA for look into papers is regularly required by understudies who can't stand to purchase their own duplicates. So on the off chance that you are among them, at that point you should realize that the vas t majority of the occasions they are more affordable than the ones purchased by libraries. The cost likewise relies upon the paper.</p><p></p><p>There are some MMLA style for look into papers. To begin with, understudies typically lean toward them when they are composing an undergrad paper. They needn't bother with this sort for a proposal, however it is acceptable to realize that MMLA isn't intended for secondary school seniors. It is generally suggested that they ought to compose a school paper first.</p><p></p><p>Another motivation behind why understudies incline toward MMLA style for investigate papers is that they realize that this paper isn't unreasonably troublesome. Along these lines, the understudy will get an increasingly exhaustive outcome as far as understanding the theme and the technique utilized. This isn't generally the situation in article papers, yet in MMLA papers, the understudy can expect this result.</p>< p></p><p>When you are picking a MMLA paper for an understudy, request that the person in question make an unfinished version. Around then, you can settle on the style you like and make it as per their choice.</p><p></p><p>To sum up, MMLA style for examine papers is useful for inquire about purposes. Understudies favor it since it doesn't require a great deal of composing and doesn't require a ton of research. Nonetheless, for secondary school seniors, they for the most part compose a theory first.</p>

The Confidential Secrets for Ib Math Essay Topics Exposed

<h1> The Confidential Secrets for Ib Math Essay Topics Exposed </h1> <h2>Ib Math Essay Topics - the Story </h2> <p>Find out whether there are rivalries or grant openings in which you'll have the option to place in your article. Your chief should offer you a touch of counsel about approaches to revise your article. In order to exceed expectations in an extended article, the understudy must plan as an approach to exhaustively create a subject. </p> <p>You may likewise allude to our Essay Outline Templates to gracefully you with a thought on how best to begin. A stretched exposition is one which you won't finish for the time being. In this manner, a systematic article is a touch of composing that gives an enlightening perception about the specific subject or thought. To secure a confirmation, you need to complete the TOK Essay and the Extended Essay. </p> <p>A wide cluster of profession alternatives are possible for the math major. The extraordinary controls of arithmetic must be regarded all through. With a little creativity you may enhance even very straightforward points to get a choice of numerical abilities. There's no specific style for the presentation, however foundation data has become the most regular procedure of approach. </p> <h2> Ib Math Essay Topics and Ib Math Essay Topics - The Perfect Combination</h2> <p>Sorry on the off chance that you were looking for explicit subject thoughts. News sources are typically solid, yet you ought to make certain to avoid tattle'' media which frequently bends the truth. When you have looked into your subject, you ought to give a decent arrangement of time organizing and sorting out your article. In case you're truly adhered attempting to find a not very wide or thin subject, I recommend endeavoring to conceptualize a theme that utilizes a correlation. </p> <p>Therefore, if there's any motivation behind why you can't have your all-encompassing exposition composed on time yourself, you should simply put in your request on our site, and leave the rest to us! The thought framing of the EE strategy is potentially the hardest piece since you don't comprehend what you're doing yet you need to compose 4000 words. As a result, it's simpler to control you won't have to peruse a hundred pages in 1 go, and if something ought to be updated you'll see the issue at an opportune time. Try not to make an extremely long compound sentence in case you're ready to compose it as two particular sentences.</p> <p>In the occasion the viable work is acted in a mechanical or college research facility, the article should be joined by methods for a letter from the outside chief laying out the character of the oversight and the level of direction gave. Talking over your favored point with your manager ought to ideally abstain from picking a poor s ubject. Guarantee you inquire as to whether there's any vital administrative work. Such reactions could be acceptable however don't address prompt needs of an understudy. </p> <h2> The Number One Question You Must Ask for Ib Math Essay Topics </h2> <p>By differentiate, superb imprints realize the all out score, which may affect an understudy's school application achievement. One of the absolute first things you ought to comprehend in winning your subject decision is that there's a contrast among history and current undertakings. On the off chance that you pick a theme excessively confounded in any event, for your administrator, there'll be a likelihood that you can't manage the point or question and end up restarting in the focal point of the year. You may even profit by completely free corrections to be particularly sure of the top notch nature of work you will receive.</p> <p>An stretched article is among the most critical components of your IB Diploma. You could be incredible at math and everything except should you not have enthusiasm for your exploration question, the examination will be very dry and exhausting and you won't end up doing your absolute best. To make an exploration paper on Mathematics isn't an issue for our essayists. You needn't bother with a point so perplexing it's educated in college. </p> <p>Math and a few of its perspectives are a critical bit of typical life. The affection for science may be incredible inspiration for you to complete an arithmetic EE. It's critical to unmistakably characterize any factors that may be utilized. </p> <h2>Ib Math Essay Topics: the Ultimate Convenience! </h2> <p>Whether there are just two books that have any association with your subject, it very well may be excessively tight. Underneath, it is conceivable to likewise find a rundown of intriguing history point proposals that you can use. Select a point you're keen on. You must limit the subject and pick a territory which you can promptly address. </p> <p>The presentation generally begins with some sort of foundation data. Additionally, verify that your 300-word theoretical is clear and quickly sums up your whole contention. A great article will clarify a solitary idea in adequate profundity and make connects all through the investigation to other pertinent ideas. An extended paper is a kind of scholarly composing task, which achievement relies on the structure. </p>

Sodium Element (Na or Atomic Number 11)

Symbol: Na Atomic Number: 11 Atomic Weight: 22.989768 Element Classification: Alkali Metal CAS Number: 7440-23-5 Periodic Table Location Group: 1 Period: 3 Block: s Electron Configuration Short Form: [Ne]3s1 Long Form: 1s22s22p63s1 Shell Structure: 2 8 1 Discovery of Sodium Discovery Date: 1807 Discoverer: Sir Humphrey Davy [England] Name: Sodium derives its name from the Medieval Latin sodanum and the English name soda. The element symbol, Na, was shortened from the Latin name Natrium. Swedish chemist Berzelius was the first to use the symbol Na for sodium in his early periodic table. History: Sodium does not usually appear in nature on its own, but its compounds have been used by people for centuries. Elemental sodium was not discovered until 1808. Davy isolated sodium metal using electrolysis from caustic soda or sodium hydroxide (NaOH). Physical Data State at room temperature (300 K): Solid Appearance: soft, bright silvery-white metal Density: 0.966 g/cc Density at Melting Point: 0.927 g/cc Specific Gravity: 0.971 (20  °C) Melting Point: 370.944 K Boiling Point: 1156.09 K Critical Point: 2573 K at 35 MPa (extrapolated) Heat of Fusion: 2.64 kJ/mol Heat of Vaporization: 89.04 kJ/mol Molar Heat Capacity: 28.23 J/mol ·K Specific Heat: 0.647 J/g ·K (at 20  °C) Atomic Data Oxidation States: 1 (most common), -1 Electronegativity: 0.93 Electron Affinity: 52.848 kJ/mol Atomic Radius: 1.86 Ã… Atomic Volume: 23.7 cc/mol Ionic Radius: 97 (1e) Covalent Radius: 1.6 Ã… Van der Waals Radius: 2.27 Ã… First Ionization Energy: 495.845 kJ/mol Second Ionization Energy: 4562.440 kJ/mol Third Ionization Energy: 6910.274 kJ/mol Nuclear Data Number of isotopes: 18 isotopes are known. Only two are naturally occurring. Isotopes and % abundance: 23Na (100), 22Na (trace) Crystal Data Lattice Structure: Body-Centered Cubic Lattice Constant: 4.230 Ã… Debye Temperature: 150.00 K Sodium Uses Sodium chloride is important for animal nutrition. Sodium compounds are used in the glass, soap, paper, textile, chemical, petroleum, and metal industries. Metallic sodium is used in manufacturing of sodium peroxide, sodium cyanide, sodamide, and sodium hydride. Sodium is used in preparing tetraethyl lead. It is used in the reduction of organic esters and preparation of organic compounds. Sodium metal may be used to improve the structure of some alloys, to descale metal, and to purify molten metals. Sodium, as well as NaK, an alloy of sodium with potassium, are important heat transfer agents. Miscellaneous Facts Sodium is the 6th most abundant element in the Earths crust, making up approximately 2.6% of the earth, air, and oceans.Sodium is not found free in nature, but sodium compounds are common. The most common compound is sodium chloride or salt.Sodium occurs in many minerals, such as cryolite, soda niter, zeolite, amphibole, and sodalite.The top three countries that produce sodium are China, United States,  and India. Sodium metal is mass produced by electrolysis of sodium chloride.The D lines of sodiums spectrum account for the dominant yellow color of the un.Sodium is the most abundant alkali metal.Sodium floats on water, which decomposes it to evolve hydrogen and form the hydroxide. Sodium may ignite spontaneously on water. It does not usually ignite in air at temperatures below 115 °CSodium burns with a bright yellow color in a flame test.Sodium is used in fireworks to make an intense yellow color. The color is sometimes so bright it overwhelms other colors in a firework. Sources CRC Handbook of Chemistry Physics, (89th Ed.).Holden, Norman E. History of the Origin of the Chemical Elements and Their Discoverers, 2001.â€Å"National Institute of Standards and Technology.†Ã‚  NIST.

History Research Paper Topics on Climate Change

<h1>History Research Paper Topics on Climate Change</h1><p>History investigate papers for the most part spin around occasions or scenes that occurred before. Be that as it may, these occasions depend on verifiable records thus they can be effortlessly summed up to a wide cluster of potential occasions. This can make it hard for understudies to comprehend these occasions as exceptional and separate entities.</p><p></p><p>For model, one of the conceivable atmosphere related points you might be approached to research would be the Little Ice Age. Some state this was brought about by volcanic movement, others fault volcanoes, and still others accuse environmental change. The fact of the matter is, these researchers can give you alternate points of view, yet they don't all concede to how environmental change began or why. Actually the discussion over this theme can take a ton of room.</p><p></p><p>Another conceivable atmosph ere related history look into paper point, you may be approached to consider could be the ascent and fall of the Roman Empire. Numerous history specialists feel that the ascent and fall of the Roman Empire were straightforwardly identified with atmosphere. Some even contend that atmosphere is the fundamental driver of the destruction of the Empire.</p><p></p><p>Perhaps, there is one all the more profoundly significant occasion that added to the breakdown of the Roman Empire. It is a frequently referenced theme, and it identifies with the utilization of coal. During the last long periods of the domain, the utilization of coal turned out to be increasingly pervasive, which added to a decrease in the realm's production.</p><p></p><p>The occasions referenced above may simply be a hint of something larger with regards to conceivable atmosphere related history examine paper subjects. They are among the more typical and notable environmental change stories that are being expounded on. You should gain proficiency with everything you can about the different various situations as this can assist you with bettering comprehend the situation.</p><p></p><p>We can never foresee when or what specific atmosphere changes may turn out to be increasingly normal. What is almost certain however is that every one is an aftereffect of long haul changes that have been occurring in the course of the last hardly any thousand years. Most scientists in this field concur that the warming of the planet has been expanding in ongoing decades, which can just prompt increasingly potential scenarios.</p><p></p><p>It's hard to gauge precisely how much an Earth-wide temperature boost we are confronting today. In spite of the fact that it is notable that carbon dioxide discharges have expanded in the course of recent decades, researchers are as yet discussing the real degree of this an unnatural weather change. The most ideal approach to make sense of the specific measure of a dangerous atmospheric devation is to lead careful research. You have to know the ebb and flow climate designs, regardless of whether you live in a region that isn't encountering significant climate issues currently.</p><p></p><p>History look into papers on environmental change typically revolve around previous authentic occasions, just as their consequences for our present reality. They can be utilized as authentic guides to all the more likely represent how occasions in the past have impacted the present. Any future students of history, you may need to look into this subject will without a doubt locate a lot of data to discuss.</p>

The Nuiances of Critical Essay

<h1> The Nuiances of Critical Essay</h1> <p>It's fascinating that various understudies compose presentation after they've composed the entire paper. Understudies who don't see how to create a fundamental investigation paper ought to procure arranged to separate the entire into pieces and after that review the part. On the off chance that you might want to acquire an examination paper, web based composing administration like our own is actually what you need. There are a few things that may bomb recorded as a hard copy a systematic paper that the delineation of an article might be the best way to forestall any mix-ups and present a paper that will get you the most extreme evaluation. </p> <p>Have a gander at our value mini-computer to find what your ideal cost for the paper is! Request first class article as of now and guaranteed pros will do their absolute best to gracefully you with higher caliber at reasonable cost. It's difficult to choose a help to buy your article from. For an increasingly elaborative perspective, you can develop up more components dependent on the necessity of your article paper. </p> <p>Therefore your decision might be restricted to what you will probably wrap up. You have to get a theme and start by giving a presentation. The point of an essential exposition is to examine another person' proposition or work by offering own thoughts moreover. </p> <h2> The Debate Over Critical Essay</h2> <p>A pivotal paper is composed to fundamentally portray the idea of the subject of that exposition. At whatever point your investigative paper is completely composed up, they can let you ensure it's as incredible as it can get. These days you've learned hot to create a great abstract investigation exposition however on the off chance that you need help with it, you generally have the alternative to get some information about it. At the point when you see how to create a great scholarly investigation article, you can communicate your thoughts and make an examination of any piece of writing which you've perused. </p> <p>Critical paper isn't an outline of a book and isn't a diagram of the film. At that point begins composing your presentation, it won't get you occupied from the essential focal point of the exposition. Writing understudies read a decent arrangement. </p> <h2> Why Almost Everything You've Learned About Critical Essay Is Wrong</h2> <p>Although you may accept that such paper may be utilized distinctly in a negative importance, you should realize that it might be utilized as a positive assessment of a specific book, sonnet, article or something of the sort. There aren't numerous things that must be viewed as when composing a significant paper. When composing inventively, there are various issues you should consider. There are uncommon words and word blend used for investigative purposes which should be adapted as well. </p> <h2> Why Almost Everything You've Learned About Critical Essay Is Wrong </h2> <p>Or you may be directing a urg ent way examination to assess and design complex work methods. In addition, it will help you in making notes and references that you may later use in the chief segment of the activity. From that point forward, plot what parts of the activity you're probably going to talk about. A urgent eye to the content or the work is everything that you have to make your paper an enormous achievement. </p> <p>You may utilize statements or rework locales of the content so as to include proof. For example, assume you're examining Moby-Dick. Having an objective is in reality critical to composing a decent significant exposition and it is essential to diagram it plainly. Sex entertainment article composing might be a genuinely straightforward assignment as there's a lot of data out there effectively on the web and disconnected. </p> <h2>Critical Essay - What Is It? </h2> <p>The above is of astounding centrality, particularly to understudies who imagine that basic p apers should focus on the negative aspects of a subject. Ensure your conversation is effectively sorted out. Subjects can change contingent upon your majors. Furthermore, you may have opportunity to pick any theme you like. </p> <p>A Real Estate organization not at all like some other fixated on the mission of building a system of vocation disapproved of aces who endeavor to develop their association and their future. Simply take some time toreally take a gander at the specific employment. You should simply have a fair methodology towards the activity. Our work isn't to duplicate glue and produce a report. </p> <p>You could make 1 case with bunches of proof, or five professes to reinforce your subject sentence. The proof may take the sort of an analysis. Remember that the main role of composing this sort of article is to find a thought theory and bolster it with satisfactory contentions. A few people may even decide to create an erotic entertainment expositio n expressing that sex entertainment isn't right. </p> <p>If in the wake of following the means and observing the exhortation and deceives, you think that its hard to form a critical examination, don't be reluctant to ask help from EssayPro. In the event that you're ambivalent to pay an individual to create your paper, investigate different features of our sites or contact our help group for any additional rules. Basic examination layouts are used to draw a vital investigation of the endeavor. Basic investigation position layout supplies you a way to make the significant examination on a specific subject. </p>

Using Examples As an Example

<h1>Using Examples As an Example</h1><p>Writing an article about a spot to secure models are an extraordinary approach in the event that you have never composed a paper. They are additionally a decent method to build your capacity and become increasingly acquainted with the language and style that are utilized in paper composing. There are three primary kinds of models for you to pick from.</p><p></p><p>Examples are given as a source and as a rule alluded to in a commentary or a heading. These incorporate citations, direct statements, refrains, and models. Truth be told, models can be very useful with regards to article composing. For instance, an immediate citation is a precise statement from another source. In a paper, this would demonstrate precisely what is being stated, while if the citation is from a work of fiction, it would normally be a summary or some other variant of the first quote.</p><p></p><p>Examples ca n likewise be a sentence that isn't from another source. It is the nearest the exposition essayist has gone to the first source. The things about which the statement is communicating can be straightforwardly referenced, however not really in the essay.</p><p></p><p>One of the upsides of utilizing models as models is that you will realize where to allude to the material on the off chance that it is muddled. This can spare you from making mistakes that would make a peruser more averse to give you the evaluations you need. When utilizing models, perusers ought to know that a section could be in struggle with what is being written.</p><p></p><p>Because models give a nearby perusing of the first source, they are likewise useful for an article to be composed utilizing more than one thought. You can utilize the guides to help some thought and don't need to re-compose the whole paper each time you utilize a model. In any case, one thought can' t be bolstered by one model. Notwithstanding, on the off chance that you utilize more than one thought, one thought can be upheld by various examples.</p><p></p><p>Another advantage of utilizing models is that they are acceptable approaches to help an article essayist build up a range of abilities. Model use can even mean you increase a comprehension of a theme or a thought. In the event that you compose on a point that you have been taking a shot at previously, you may utilize guides to gain some new useful knowledge and execute it into your exposition writing.</p><p></p><p>Essays are a significant piece of any composing course, regardless of whether it is on the web or disconnected. With regards to paper composing, models are a significant part of having the option to compose and introduce content to pass on an idea.</p>

Essay Topics For Fifth Grade - Choosing the Best Argumentative Essay Topics

Essay Topics For Fifth Grade - Choosing the Best Argumentative Essay TopicsThe way to writing argumentative essays in fifth grade is to be very careful about the essay topic you choose. The subject matter is important because this will dictate the style of the essay. For example, if you are writing an essay on the mental aspect of our society, you should use your choice of words carefully. Also, the key facts of the topic are more important than any words used in the essay.Arguments are made in a variety of ways. It may be through biography, fiction, or opinion. When writing an argumentative essay for fifth grade, you need to realize that your topic will determine how your essay is written. This is just like in English class. You do not use words from other subjects to come up with a conclusion about a particular topic.Here are some essay topics for fifth grade, you may consider. You can choose to write an essay on stage fights in the back stages of the Civil War. You can also write an essay on how the weather affects people on the grounds of climate change. The latter may seem odd, but you can use the word climate instead of climate change to explain how the weather influences your subject. Just keep in mind, there are certain words that have specific meanings and you have to be aware of that.You can also decide to write an essay on the way we talk now. If you have an opinion, then you can write an argumentative essay on how people speak. A good essay topic for fifth grade is on the way that language changes. Therefore, you should be very aware of what words are acceptable to use in a given argument.A good essay for fifth grade argumentative essay will answer the question asked by the question. The essay will not contain an opinion. It is best to begin with a thesis statement, then move to an explanation as to why the thesis is the one that you believe.Argumentative essay topics for fifth grade are different from the first-year essay topics that your teachers will give you. The latter are usually based on past events. The arguments in these essays can go into a bit of detail about certain instances and how they were viewed at the time. This allows students to see firsthand the opinions that others hold. In addition, this helps students to make up their own opinions that fit their understanding of a particular event.An argumentative essay should not seem too wooden. Instead, it should make you sound intelligent. Make your essay clear and concise; and avoid using colloquial terms such as 'um'like.'Arguments are a great part of the writing process in fifth grade. You have plenty of opportunities to learn to use the written word to explain your point of view. However, you need to choose the best argumentative essay topics for fifth grade for your particular essay.

Realism in 21st Century Free Essays

Realism in 21st Century The world, in view of the fact that it was created is changing. With the changing desires and demands of today’s standard of living, individual needs to be in sync with the demands and trends of modern day living. Not too long ago, people were seen doing stuffs that have turned out to be more of a routine in today’s humankind. We will write a custom essay sample on Realism in 21st Century or any similar topic only for you Order Now Every single day a new type of technology is been introduced in today’s world. So, the question arises that is theses changes necessary in today’s world? If yes, does it have a good or a bad impact to the human society in today’s world? We need to talk about in which approach hi-tech advancements that pace into our daily lives have altered our lifestyles in the very last few centuries. In today’s world each and every single people rely on new and advance technologies. Everyone loves new technologies and gadgets that promise innovative and better ways of living. A pace of life is frequently increasing with the increase in new technologies. Nowadays somewhat more a quarter of the earth’s population can be found in the industrialized societies. And half of the population still lives on past agriculture, but they are also relying on machines. The remaining of the world’s population, however, is no longer of either the past or the present. They live in the future, within the most important centers of cultural and technological change, in New York, California, Cambridge, London and Tokyo (Toffler, p. 38). A new part of technology is like a new relationship to an individual, it will be cool and thrilling at the first, but sooner or later it gets addictive to the people. I doubt technology’s give your word to improve the quality of life, makes our life easier and simpler, but it gets more addictive and makes one lethargic. People have turn out to be physically and psychologically dependent on many behaviors and substances for centuries. The compulsive and frequently use of these technologies have negative impact on our daily lives. The key life areas that appear to be impacted are relationships, health, employment, and financial status. In the present day people find their reality have changed because they have to get used to the new culture and behavior according to the pace of technology. Presently people like to live in this current industrialized era but some of them are overwhelmed by the change of new technologies and inventions. Changes in the life are important, but the acceleration of changes leads to the victim of overchoice and impacts on our personal and psychological, as well as sociological, consequences (Toffler, p. 2). Philip Morris now it is Altria Group, for example, when it was introduced in USA in 1954, it only sold a single major brand of cigarettes i. e. Marlboro specifically to men. By now Altria Group has introduced additional 16 new brands with so many options with respect to size and flavors (Toffler, p. 265). Not only in cigarettes there are many overchoices in food, clothing, gasoline, and many more. There is a huge diversity in education industry too, students have a huge selection on what field they want to study and nowadays students can even get their degree online. More often than not society does not leave freedom for avoidance and as a result one need to adjust and learn about the new technologies that become part of our lifestyles. These days when people are faced with having to decide one option out of many popular choices, they will start on to think about imaginary trade-offs. The people do make their best choice out of the variable products, but afterwards it affects their level of satisfaction they had from the one before. The people now can’t escape this situation of freedom because they are not committed to the choice they make. People don’t know that the current loads of choice over and over again lead to feelings of loneliness and depression. The creation of the Internet has been the main source of innovative information, connectivity, and possibilities to create new private freedom. There are presently more than a billion web pages of information on the Internet about every topic that you can think of. The Internet users around the world have been increased by 444% since the starting of the 21st century (Internet Usage Statistics). In this era, computers and Internet are an important part of everyday life. Computers are used everywhere. Today Internet and computers can exactly take us to the different worlds and different realms of reality by a thought referred to as virtual reality. Inception is the latest â€Å"virtual reality† movie of this time. In this movie Leonardo DiCaprio plays an unlawful with the technology to plan himself into the dreams and ideas of others. The characters spend an important amount of time entirely powerless with beeping tools nearby. In the meantime their minds are busy occupied navigating avatars in a virtual world of Inception. In this movie, a machine would let you to connect to a virtual atmosphere by getting into someone’s dream. Even in the movies â€Å"The Matrix† and â€Å"Avatar† was computer generated and were in the different world of imagination. In â€Å"Plowing the Dark† by Richard Powers, on one side of a story a band of researchers in Seattle working on a 3D reality on how an empty white room that can become a jungle, a painting, or a Byzantine cathedral. And the other follows an individual kidnapped and held hostage by terrorists in Lebanon in an empty white room, equipped only with his imagination and memory. In the novel, the two stories overlap, but the people in the different stories do not know one another and never communicate. But at the end, the imaginative experience of Adie and Taimur intersect, with Taimur’s control leading to an unexpected change in Adie’s life and Adie inspiring Taimur at a serious moment. In this novel, the author addresses this issue of creating an inspiring character of life in an unreal environment that becomes frightening real to us (Powers). The novel â€Å"Plowing the Dark,† alludes to several poems including â€Å"Sailing to Byzantium† by W. B. Yeats. In this poem, Yeats highlights the aspect of world he lives in, is scared of becoming older and complains about the world he lives in, so he decides to escape to the city i. e. Byzantium where the poet can achieve immortality. In all the movies (â€Å"Inception,† â€Å"The Matrix,† and â€Å"Avatar†), the novel â€Å"Plowing the Dark,† and the poem â€Å"Sailing to Byzantium† the people wants to escape the real world and wants live in their own virtual mind and places they created. Virtual reality is becoming more prominent and dangerous as the days passes. One can assume a second identity in their imaginary world through the Internet. In 2003, a game called â€Å"Second Life† appeared on the Internet, is an online virtual world mainly targeted to the children who are aged thirteen and over, and as of 2011 â€Å"Second Life† has more than 20 million egistered user accounts (Secondlife). They can get married, have children, rob banks, and shoot people all in the name of fun. Virtual reality makes it a good tool for education because it allows children to learn in a more interactive environment where they are m ore likely to retain information. But it also has some negatively psychological and social effects. These days many students are showing a decrease in usual emotion and affection due to their stable communication with lifeless cyber friends. Cyberspace can be a help out, but when used in the wrong behavior it can be very damaging to our physical and mental well-being. Virtual reality in fact minimizes the significance of our physical bodies and encourages people to misuse their time. It causes people to get lost from exact relations by focusing on the mind freezing effects of video games and online cyber world. In this generation, the Internet is so ingrained into our lives that life without the access of Internet is completely unimaginable. The use of the Internet offers a variety of benefits to every person in today’s world. Internet has a giant amount of information added on it every day and it’s developing as the most powerful source of information. Also, use of the Internet makes easier to find jobs in a minute. One can also buy and sell things on the Internet. Last, the Internet is one of the most important tools in educations seeing as it provides a massive amount of information and is the greatest source of reference for teachers and students. The Internet has influenced, and is still influencing the way culture communicates in a lot of different ways. The rise of the Internet has caused people to communicate differently in areas never dreamed of before the Internet came into existence. In the book, â€Å"The Shallows: What the Internet is Doing to Our Brains,† by Nicholas Carr argues that surfing the World Wide Web is causing the damage to your brain. This book has been expanded from the article, â€Å"Is Google Making Us Stupid,† by the same writer Nicholas Carr. In this book, Carr describes how human thought has been changed through the centuries by â€Å"tools of the mind† – from the alphabet to maps, to the printing press, the clock, and the computer (Carr). This all tools are very useful in this 21st Century in getting directions, determining time and finding information on the computer through the Internet which is very faster and saves a lot of time. This all tools are easy and convenient in today’s life, but the effect of all this tools is that it is breaking the focus and the creativity of the human brain. Carr in the article, â€Å"Is Google Making Us Stupid,† stated that one he was a scuba diver in the sea of words, but now he zips along the surface like a guy on a jet ski. This is nothing but the Internet, which, with its search engines, blogs, social network such as Twitter and Facebook, pornography and online games has chipped away the capacity for concentration and contemplation. I totally agree with Carr, that when we use the Internet, we totally enter into a different environment; we enter into the world which is not real, that leads us to quick reading and diverts our thinking and distracts our brain. Right now, you can take example of me, as I am writing this paper or whenever I find myself assigned with a research paper for class I get simply unfocused from looking up references online and manage to find myself on completely unrelated websites. The pop-ups and the advertisement usually get our mind diverted. Then after half an hour of researching I find myself on checking the emails, uploading status or new photos on Facebook or either playing games on the computer. Then I realize that I have wasted almost an hour doing nothing instead using the time sensibly. Yes, Internet is the main source of information, but is actually affecting our brains. Not only Internet, the smart phones, TVs, online video games and many other digital technologies also damage our brain. According to a survey published by Forrester Research, Americans are now spending a large amount of their time using the Internet than watching television, and the amount of time people spend on the Internet has increased 121 percent in excess of the last five years (Joshua). The amount of time spent on the Internet not only has been increased by the teenagers or adults, but also have been increased by up to six to eight hours a day among the people over 66 years. But the rapidly increase in the use of Internet has not affect a drop in television consumption for the reason that the Internet, and mostly the mobile Internet, cleanly creates additional facilities and opportunities for the nation to consume media. In today’s world, TV is still important, but the content where the people are getting from is changing. Nowadays, most of the people are getting the content from the use of the mobile Internet. Smartphone and tablets are a life changing to many users since it is so personal, in terms of how and how frequently the device is carried and how it is used to connect and to expand relationships. Smart phones went from being a luxury and became an everyday tool for students, employees and the businessmen. For a lot of us, communicating with friends and family used to mean writing letters and cards via mail and have to wait for weeks for the response. But now we communicate with each other through emails and text messages in a fraction of seconds. Now younger generations have forgotten how to write and spell a complete sentence due to rapid increase in text messaging. Teenagers are totally reliant on simple tenses and a limited use of vocabulary, and that to with the help of spell check. At the same time there is also a reduction in a personal face to face communication. Nowadays, people just text message their friends, chat online, do discussion on the blogs, and they even date online. Due to these changes; the people have mentally changed their communication skills. People don’t know that more and more use of the technologies gets addictive to them and changes the mental and physical shapes of the brain, and can lead to a decrease in the sense of self and human identity. Our neurological systems are actually being spoiled, and we are less able to process and remember information, even if we are continually reading, or surfing, online. The person who spends more of their time playing games and reading web pages are experiencing visual problems. Most people are clueless that how the cell phones affects their brain by the radiation. In J. D. Salinger’s â€Å"The Catcher in the Rye†, the main character of Holden Caulfield views the humankind as a place where the most human behaviors such as love, sympathy and kindness are all been overridden by the power of money and technology. Holden Caulfield is desperately holding to the concept that necessary human kindness is far more vital to a joyful way of life than material wealth and technology. Holden in the novel feels similar to a loner or a rebel in an environment where the people are dishonest and corrupted, and he is badly looking for someone to talk to that will make him happy. In the beginning of the story, Holden says, â€Å"As a matter of fact, I’m the only dumb one in the family† (David, p. 67). In the whole story, Holden describes himself as a failure and immature, and also has been told by his parents, friends, and teachers number of times but still, Holden every time hangs to his ideals and looks his failings as almost laughable. In the story, Holden is suffering from mental and emotional problems due to his attitudes and behavior. The only thing that can â€Å"cure† Holden, as stated in the story, is to get more and more interaction with the people around him. From the novel, â€Å"The Catcher in the Rye†, possibly one can learn from the main character, â€Å"Holden Caulfield†, that in regards to corruption, wealth and the dream, foes not matter how expensive and attractive it is, but only the true pleasure and satisfaction can only be establish from within. Holden also oversimplifies the whole lot and in his view children are straightforward and innocent image of wholesome life compared to adults who are by now influenced by the accepted public way of life, which adjusts or fakes everyone’s realism. An individual in our society today feels that, they are separated from one another and has lost the interaction between people same way, as Holden in the novel, â€Å"The Catcher in the Rye†. †¢JOSHUA, BRUSTEIN. â€Å"American Internet Use Catches Up With TV Use. † (2010): Web. 2 May 2011. . †¢Ã¢â‚¬ INTERNET USAGE STATISTICS. † (2011): Web. May 2011. . †¢TOFFLER, ALVIN. Future shock. Bantam, 1984. 38. Print. †¢TOFFLER, ALVIN. Future shock. Bantam, 1984. 2. Print. †¢TOFFLER, ALVIN. Future shock. Bantam, 1984. 265. Print. †¢CARR, NICHOLAS. â€Å"Is Google Making Us Stupid? â€Å". Atlantic Magazine July/Aug 2008: Web. 2 May 2011. http://www. theatlantic. com/magazine/archive/2008/07/ is-google-making-us-stupid/6868/. †¢DAVID, JEROME. The Catcher in the Rye. Little, Brown and Company, 1951. 67. Print. †¢POWERS, RICHARD. Plowing the Dark. Picador USA, 2001. Print. †¢Ã¢â‚¬ Secondlife. † Web. 2 May 2011. How to cite Realism in 21st Century, Papers

Student Attendance free essay sample

This project focuses on the development of a web based attendance register system, called mobile student attendance monitor. This project is motivated due to the fact that the students attendance record is the most important element which can reflect their academic achievement in the institutions. Mostly, the attendance register is circulated in the lecture rooms by the lecturers. This is a very time consuming method and not ideal for a large number of students in a big lecture hall. The aim of the project is to develop a user friendly, efficient and effective mobile attendance system that provides an alternative solution to manual attendance in the educational institutions. The development of this prototype system has been built using the web-based applications such as PHP, My SQL and VB. NET to deal the students attendances by using RFID reader. As, most of the academic institutions provide their students and staffs, ID cards with RFID tags on them. These cards are also known as Contactless smart cards. This project is designed to collect and manage student attendance through this technology which works on the verification basis of the students and recording their time of entrance and exit in the lecture hall. Keyword: web based prototype, PHP, MySQL, VB. NET, RFID, readers, tag, and contactless smart cards. INTRODUCTION OF THE PROJECT AND THE SYSTEM Introduction Management in organizations is a very important aspect in every field as economy is growing at a very fast speed in this busy world. One of the most important factors of the management of nearly all the organizations is to keep the records of the attendance of the individuals. Many researches and the evidences in them have shown that there is an important relationship between the attendances and the performances of the individuals. If the individuals do not attend the places, their performances will link to poor retentions and results. The development of this system is provoked due to the fact that the students attendance record is one of the important elements that may reflect their academic achievements in the institutions. For the sake of good results, it is also very important for the institutions to keep the records of the students at all times. As having the accurate and more powerful attendance systems, it helps in the monitoring of the students activities and their interest in the course. With the help this kind of systems, it would be very easy to handle the record management. Importance of Attendance Empirical evidences have shown that there is a significant correlation between students attendances and their performances [1]. This aspect is agreed by both Mazza and Dimitrova where they claimed that this factor is the most important aspect which indicates the behavior of the student for the course. With the help of this analysis, the judgment can be made about their tendency and dedication of the students toward the courses. [2]. Results taken from the study done by Newman-Ford, Lloyd and Thomas have shown that attendance was a significantly better predictor of grade than any other factors such as age, prior education background or even gender [3]. From the study, it had also revealed that retention rates were substantially better for students who were consistently attending classes than those more frequently absent. All of these findings have showed that attendance records have primarily become the proxy to determine the success of the students in most of the higher academic institutions. [4] Manual Attendance System Traditionally, in most of the higher academic institutions, the recording of the students attendances are mainly done by paper and pen. On the other hand, this practice will also lead to human errors that could be happening during or after the process of attendance taking. For this process, the attendance sheets are to be distributed in the classes for the students to sign in and this whole process consumes a lot of time. Sometimes this list requires the registrant to write his/her time of entry to the classroom as well. In most cases, there is not any list available and students have to write their names on a plain piece of paper plus their signatures and possibly ID (Identification data) numbers which are assigned to them by their institutions. By using the manual system, the process of attendance becomes more difficult for the management to update the record regularly and manually calculate the percentage of classes attended [5]. All of these limitations regarding the manual system indicate the needs to improve the process of attendance recording and reporting. Using papers are not just inefficient but it will require the management of the academic institution to provide a well-managed filing system to cater the attendance records. Therefore, it is crucial to reinforce the use of attendance register system in order to improve the process of recording and reporting students attendances in the higher academic institutions. [4] By proper analysis of this method, we can observe a lot of problems in the process which are unsuitable for the system. If we start the whole procedure from the beginning, we can notice that each student has to look his/her name up on the list which takes some time, some fellow students can sign for their friends and colleagues who are absent and the lecturer could not identify the signatory, any mistake can occur like list do not have proper names, times for entering in the lecture hall and their registration numbers on the list, the list would be difficult and time consuming to circulate in large lecture rooms consisting of high number of students, some students may forget to sign their attendance on the register. For the lecturer, it might be a big hassle to pass this to the department of administration because of their busy schedule and timings. Especially for the administration; its always a tough task to keep the records over a long period of time which may confuse them when searching for the record of a specific student in particular dates. Web Based Applications Web-based applications have now become one of the preferable technologies that are used to ease the process of managing data and records. Some of the motivations that contribute to the development of any web-based systems nowadays are because of its efficiency in handling rapid access of documents and its ability in supporting multi-users simultaneously, thus saving a lot of time and hassle free [6], [7]. Web based applications have many advantages over software that you have to download. You dont need to install or update anything on your PC. You can use the application from any PC or mobile device. Web applications are easy to use and make working with other people much simpler. You dont need to worry about backups because your data is safely stored on a server. [7] Furthermore, web-based applications are designed with the same principles as a regular website. So, it is as simple to use a website as to use a web-based application. [8] Use of RFID in the System Recording the students attendances has also become the prospective process to be automated by using the web-based system. Many researches are involved in more advanced technologies that are integrated with the online systems such as the use of bar code technology, biometric technology and Radio Frequency Identification. These days, mostly all the institutes and organizations do provide their students with ID cards which have been integrated with RFID transponders which contains the basic details of the card holder. These cards may have different details like the student registration number, roll number, name, batch number and department ID and the department name etc This ID card which is also known as Contactless smart card is provided to the students for the access to different premises in the university like laboratories, libraries, buildings, seminar rooms, parking lots and class rooms. To access different areas, students have to present their ID cards to different machines which are mostly called scanners or readers, located in campus in the university and these machines are capable of reading ID cards even they are not touched with them. For this project, in order to design a system, first we need record the attendance of the students using their ID cards. This system is equipped with an RFID reader which reads student ID cards and records their time of attendance at each lecture, into its memory. In order to take the attendance, lecturers can connect this machine to an external host station to print a full list of students attending lecture and the list can be easily viewed by them. Project Outline * Chapter 2 provides the basic idea about the automatic identification system and its general types * Chapter 3 focuses on the technology overview of RFID system * Chapter 4 focuses on the system design and implementation. * Chapter 5 discusses the evaluation and testing of the different scenarios of the system * Chapter 6 concludes the project and recommendations for the future work AUTOMATIC IDENTIFICATION SYSTEMS In recent years, the automatic identification systems have become very popular as they are providing services in many fields like industries, purchasing and distribution logistics, industry, manufacturers and material flow systems. These are the systems which exist so they can provide information about humans, products, animals and goods in transport. Barcode Procedure Bar codes have successfully held their own against other systems over the past few years, as the turnover of the bar codes in the decade of 90s. The bar code system consists of bars and gaps arranged in parallel configuration which is a physical representation of a binary code. They can be either narrow or wide which also have associated numerical readings. For this reason they are arranged in a pattern which is decided and they are representing data that refer to an associate symbol. All bar codes represent data in a machine readable form. Different bars and spaces in a bar code represent different numbers and letters which can be decoded with the help of a bar code scanner. When they are scanned by optical lasers, the white gaps and black bars produce dissimilar reflections from the laser beam which provide for different sets of codes. This scanned data is then sent to a computer where it is recorded and then processed. [10] In addition, there are many barcodes which are popular in the industry, they are as follows: * Code Coda bar * Code 2/5 interleaved * Code 39 * Code 128 * UPC Optical Character Recognition This type of identification system was developed in the 1960s. Optical character recognition is usually abbreviated to OCR. OCR is a field of research in pattern recognition, and artificial intelligence. It is the mechanical or electronic translation of written images, typed or printed text into machine-editable text. It is used to convert paper books and documents into electronic files. When a paper is scanned, it produces just an image file, or a photo of the page. As the computer cannot understand the letters on the page, so OCR software is used to convert it into a text or word processor file.. The result is much more flexible and compact than the original one. All OCR systems include an optical scanner for reading text, and sophisticated software for analyzing images. Most OCR systems use a combination of hardware and software to recognize characters. OCR systems have completely failed to be deployed in the different fields in the world as the scanners are highly expensive and the readers are complicated in comparison to the other readers of the automatic identification systems. Biometric Procedures This is a unique method for recognizing humans which is based on one or more intrinsic physical or behavioral characteristics and qualities. The main purpose of this system is to identifying human beings by detecting and comparing the physical characteristics of each person such as hands and finger prints and with the help of their voice and iris. Finger Identification Systems Finger print is one of the most important procedures in this field and its applications are used to identify criminals. It is most developed of all the biometric technologies and its price is low enough to see it beginning to make inroads in to the mass market. When this procedure is run to identify personal identification, the finger is placed on the specified reader. The system calculates it pattern and this analysis of fingerprints for matching, generally requires the comparison of several features of the print pattern. These include patterns, which are aggregate characteristics of ridges, and minutia points, which are unique features found within the patterns. It is also necessary to know the structure and properties of human skin in order to successfully employ some of the imaging technologies. Voice Identification Voice identification technology was initiated in the early 1960s. Since then, voice ID has undergone aggressive research and development to bring it into the mainstream. Voice ID is sometimes called voice authentication, which is a type of user authentication that uses voiceprints and pattern recognition software to verify an individual. [13] Voice identification is possible because every person has a unique set of voice characteristics and speech patterns. Voice identification extracts specific and unique features from a persons speech, such as pitch, tone, cadence, harmonic level and vibrations in the larynx, and stores and uses them to differentiate that persons voice from the other voices. This system requires speech samples from the subject. The input is compared with a stored sample of the subjects speech. This stored sample is called a voiceprint. A voice print is a plot of frequency density vs. time. [14] Early voice identification systems made matches between sets of such plots. If these samples match, then the person can be identified or a reaction can be initiated (e. g. open door). Smart Cards A smart card, a type of chip card is a plastic card embedded with a computer chip that stores and transacts data between users. This data is associated with either value or information or both and is stored and processed within the cards chip, either a memory or microprocessor. The card data is transacted via a reader that is part of a computing system. Smart card-enhanced systems are in use today throughout several key applications, including healthcare, banking, entertainment and transportation. [15] The microprocessor on the smart card is there for security. The host computer and card reader actually talk to the microprocessor. The microprocessor enforces access to the data on the card. If the host computer read and wrote the smart cards random access memory (RAM), it would be no different than a diskette. Smarts cards may have up to 8 KB of RAM, 346 KB of read only memory (ROM), 256 KB of programmable ROM, and a 16-bit microprocessor. The smart card uses a serial interface and receives its power from external sources like a card reader. The processor uses a limited instruction set for applications such as cryptography. Smart cards can be used with a smart-card reader attachment to a personal computer to authenticate a user. Web browsers also can use smart card technology to supplement Secure Sockets Layer (SSL) for improved security of Internet transactions. [16] The most common smart card applications are: Credit cards * Electronic cash * Computer security systems * Wireless communication * Banking * Government identification Smart cards are much more popular in Europe than in the United States. In Europe, the health insurance and banking industries use smart cards extensively. Every German citizen has a smart card for health insurance. Even though smart cards have been around in the ir modern form for at least a decade, they are just starting to take off in the United States. [16] Therefore, this market represents one of the fastest growing subsectors of the microelectronics industry. They have two types, either a memory card or one with computer capacity known as a microprocessor card. The memory cards operate using a sequential logic state machine which accesses the memory (EEPROM) of the card. Security can be increased by adding stream ciphering algorithms. The functionality of the memory card in question is usually optimized for a specific application. Flexibility of application is highly limited but the advantage is the cards are very cost effective. Therefore they are used in price sensitive, large scale applications. The microprocessor cards, contains a microprocessor which is connected to a segmented memory (ROM, RAM and EEPROM segments). The mask ROM incorporated an operating system for the microprocessor and is inserted during the chip manufacture. The contents of the ROM are determined during the manufacturing are identical for all the chips from the same batch and cannot be overwritten. The chips EPROM contains application data and application related program code. Reading from or writing to this memory area is controlled by the operating system. The RAM is the microprocessor temporary working memory. Data stored in it is lost whenever supply voltage is disconnected. Microprocessor cards are very flexible as it is possible to integrate different applications in one card. The application specific parts of the program are not loaded in to the EPROM until manufacture and can be initiated via the OS. [19] THE BASICS OF RFID TECHNOLOGY What is RFID? In twelfth night, Shakespeare wrote Some are born great, some achieve greatness, and some have greatness thrust upon them. RFID is one of the more recent four letter abbreviations to have greatness thrust upon it in a flurry of industry mandates, government legislation, and hyperbole. 20] RFID is basically the abbreviation of four letters which are combined together which stands for Radio Frequency Identification. This describes a system which can identify wherein an electronic device that uses radio frequency and magnetic field attached to an electronic device. The object of any RFID system is to carry out any form of data to suitable tran sponders which are called tags and to retrieve data with the help of machine at a suitable time and place to satisfy particular needs. These are the two most important components of this system, one is tag and the other one is called the reader, which recognizes the presence of RFID tags and reads the information which is manually stored on them. This information is then passed to another system confirming the presence of tags. The software with which the system is communicated with the reader is called RFID middleware and it stands between reader and the applications. Case for RFID Much of the recent interest surrounding RFID has arisen from mandates and recommendations by the government agencies such as the U. S Department of Defense (DoD) and the Food and Drug Administration (FDA) and from a few private sector mega corporations. For instance, Wal-Mart called for its top 100 suppliers to begin providing RFID tags by early 2005 on pallets shipped to its stores. This mandate caused the companies in Wal-Marts supply chain to focus in implementing RFID solutions. Companies worked to decide which tags and readers to use and how to attach them with tags or embed them with the products and how to test the read rates for RF tags on pallets as they moved through doors or trucks. Several companies have announced their support for what are commonly known as tags and ship applications. [20] Applications of RFID RFIDs can have many applications depending on their type of functionality. They can be appropriate for different industries and commercial markets. Certain type of RFID applications characterize the whole approach of technology which can be differentiated on the basis of the considerations and implementations. The term autoid, short for automatic ID, describes any automated system for attaching an identity to an item. Real-Time Location Systems (RTLSs) are automated systems for tracking the location of an item. [21] The tree below shows the relationship between different identifications systems and the different types of RFID types. These five categories of RFID are the basic applications which can demonstrate some sense and issues in the physical implementation of this technology. Access Control Most organizations today require a performing and efficient access control system. There are many reasons for having such a system which are: 1. Enhanced security to limit access to restricted areas. 2. Tracking employee activity and . Improve loss prevention Some primary considerations for this type are counterfeiting which means that tags must be recognized and any kind of violation must be discouraged. The other consideration which is very important is tailgating, which occurs when an unauthorized object enters behind an authorized object before or after its entrance. To deal with tailgating and issues like emergency access, this can be implemented with the help of barriers which can be done by singulation, keeping a check which entity is entering through the sensors, either to allow them access or restrict them at a time. But the factor of counterfeiting is a hard process to be address and explained as many systems are been reversed and they proved vulnerable to the attacks. Therefore, strong encryption is necessary on both ends of messages and the digital signatures. An RFID access control system can provide an easy and efficient solution. RFID badges can be read from much further distances than other traditional technologies and the embedded electronic information for each badge can be over-written repeatedly. Furthermore, multiple RFID badges can be read all at the same time. Information about employee access, attendance, and duties performed, can be easily and efficiently monitored and stored in a database. [24] Tag and Ship Tag and ship applications are minimal RFID systems that allows a user to associate an RFID tag with an item, apply the physical tag to the item and then verify that tags operate properly to the attached item or not. Logistics and transportation are major areas of implementation for RFID technology. For example, yard management, shipping and freight and distribution centers are some areas where RFID tracking technology is used. Some considerations of this application are cost, isolation, tag failure and their impact on the processes. For this process, it is very important to purchase tags and device with low cost that the owner has to bear for its implementation. Therefore, a simple equipment best fits for its implementation. Furthermore, to buy some extra tags and devices lower down the cost of the maintenance of the system. It can be implemented by using simple labels that are encoded by the appliances rather than coded by tag vendors. Smart Shelf Keeping an accurate inventory of shelved items in real time constitutes is one of the most desired attributes in any retail business, resource collection, or library system. A Radio Frequency Identification (RFID) system offers an ideal way to track how often an item gets removed from or looked at and returned to a shelf. RFID uses radio-frequency communication to identify, track, and manage objects or living things via a reader and- tag system. An item fitted with RFID tag couples radio signals that a RFID reader receives to obtain the details. 26] Some important considerations for this applications are item-level inventory, hardware used and to handle the spurious tag reading. Track and Trace One of the most important and earliest of the RFID applications was to track dairy cattle. Therefore, the animals were tagged with glass capsules or ear tags which were used to identify lost animals. But now, this application is used far more like to sort information from live stock, and pharm aceutical tracking. The primary considerations of this application are information sharing and instant based control. In case of information sharing, the repetition of identification cannot be ignored therefore, unique numbers are assigned to the products so that they can be easily sorted and traced by the vendors. RFID System Categories RFID systems can be grouped into four different categories which are as follows: EAS Systems Electronic article surveillance (EAS) is a technological method for preventing shoplifting from retail stores. These systems are basically the one bit which can sense the presence or absence of an item. EAS is a technology used to identify articles as they pass through a gated area in a store. This identification is also used to alert someone if any unauthorized removal of items is being attempted. Portable Data Capture Systems Portable data capture systems are characterized by the use of portable data terminals with integral RFID readers and are used in applications where a high degree of variability in sourcing required data from tagged items may be exhibited. The readers capture data that is transmitted directly to a host information management system via a radio frequency data communication (RDFC) link or held for delivery by line linkage to the host on a batch processing basis. 29] Networked Systems Networked systems applications can generally be characterized by fixed position readers deployed within a given site and connected directly to a networked information management system. The transponders are positioned on moving or immoveable items, or people, depending on the application. [29] Positioning Systems Positioning systems use transponders to facilitate automated location and navigation support for guided vehicles. Readers are positioned in the vehicles and linked to onboard computer and RDFC link to the host information management system. The transponders are embedded in the floor of the operating environment and programmed with appropriate identification and location data. The reader antenna is usually located beneath the vehicle to allow close proximity to the embedded transponders. [29] Advantages of RFID There are many different ways to identify different objects, people and animals. For identifying small number of items of any kind object, the policy to count and write them on a paper is fine but when the number grow more than hundreds, some kind of automation is required, in a limited number of hours. To summarize, some of the benefits of RFID are the following: Alignment is not necessary: A scan does not require line of sight which saves time in processing that would otherwise be spent lining up items. Item level tracking: Different types of tags are used which have the capability to track the number of items. Re-writ ability: Some RFID tags are written and re-written many times which is a big advantage. For an item on a store shelf, this type of tag might be a security liability, so write once tags are also available in the market. So, tags can be reused and therefore extremely low maintenance cost occurs. Variety of form factors: Tags are available in a great range of types, sizes and materials. RFID tags range in size from a lunch box to a tiny passive tags smaller than the grain of the rice. Different tags are used for different purposes in wide variety of environments. High speed inventory: Multiple items can be scanned at multiple times. Therefore, it results in extreme low error rate when tracking bulk of items. Labor saving technology RFID technology is a labor-saving technology. This translates to cost savings. System Components of RFID RFID uses wireless communication technology and the basic purpose of the system is to identify objects and people which are tagged, there are three basic components as below: * A tag: Tags are also known as transponders. A tag is an identification device attached to the object we want to track or identify. * An Interrogator: This device is also referred as reader. A device that can recognize the data stored in the RFID tags. A reader is composed of an antenna, an RF electronics module, and a control electronics module. A controller: Interrogator reads the information/ data on RFID tags and passes this data to a workstation. The workstation usually runs software or middleware are to control and manage the required actions associated with the tags. The tag and the interrogator communicate information between one another via radio waves. When a tagged object enters the read zone of an interrogator, the interrogator signals the t ag to transmit its stored data. Tags can hold many kinds of information about the objects they are attached to, including serial numbers, time stamps, configuration instructions, and much more. Once the interrogator has received the tags data, that information is relayed back to the controller via standard network interface such as an Ethernet LAN or event the internet. The controller can then use that information for a variety of purposes. For instance, the controller could use the data to simply inventory the object in a database, or it could use the information to redirect the object on a conveyor belt system. [30] Tag RFID tags are the object tracking devices that are used to store and transmit data to the interrogator. These tags are made up of an electronic chip and an antenna. The electronic chip contains memory (for data read/write purpose) and other usable circuitry. Batteries may also be encapsulated with chips and antennas to provide on board power source for RFID tags RFID Tag Shapes and Sizes RFID tags can be manufactured in several different shapes and sizes depending on the type of application in which they will be used. Some are the size of a pencil lead or are less than a half-inch in length and can be inserted under the skin of animals and livestock. Screw-shaped tags are used to identify specific trees. * Rectangular RFID tags found in some products are used as an anti-theft device. * Large, heavy duty tags that are several inches in length, width, and depth are used to track large containers or large vehicles such as trucks or rail cars. [31] Basic Types of RFID Tags There are two types of RFID tags: * Active tags ( self –powered ) * Passive tags ( no battery ) * semi-passive tags ( Combination of Passive and Active ) On board power source is the main differentiating factor between these tag types. Active Tags Active tags have their own power source to broadcast signal to RFID reader (interrogator) and power electronic chips. These tags have comparatively larger memories and are much complex than passive counterparts. Usually a battery is used as the power source. By using a battery as power source, active tags are able to transmit data and communicate with low-powered RFID readers. Another advantage of using active tags is that it can transmit signals over relatively longer distances. The complexity, power source, and larger memories make these tags more expansive. Passive Tags Passive tags have no power source and rely on RFID readers. These tags derive power from the signal sent by RFID readers. Due to this fact, these tags require high powered RFID interrogators and have short effective range (usually less than 2 feet). Passive tags have smaller memory capacities as compared to active tags due to power source absence. As a result, these tags are much less complex and are less expansive to manufacture. Semi-Passive Tags Some passive tags have built-in power source but do not use this source for signal transmission. In fact, they use power source for on-board circuitry. Such types of tags are called battery-assisted passive tags or semi-passive tags. Basic Tag Capabilities Many basic operations can be performed with an RFID tag: * Attaching the tag: Any RFID tag must be attached to an item through some way. * Reading the tag: tag must be able to communicate with the reader through radio frequency. * Write once: Some tags are manufactured with their values at the factory, but some are left as the user can write once on them and after that the tag values cannot be changed and manipulated. Write many: some tags are manufactured for a reason that the data can be written again and again on them. * Anti-collision: these are some intelligent form of tags which can wait for their turn incase, when many tags are in close proximity. * Security and encryption: some tags are more intelligent as they are able to participate in encrypted communication and they can respond to those readers only, which can prov ide a secret password. * Disable: once tag is disables, it never responds to the reader again. Selection of Tags Many considerations are important in the selection of the tags which are as follows: * Read range: Active tags provide a longer range than the passive tags. For the purpose of the retail, the read range is fulfilled by the passive tags. * Material: In order to deploy the RFID tags in different materials, it is very important to keep in mind where they will be used. For example, in case water or metal, radio frequency or their waves may be obstructed and hamper down. * Cost: This is the most important of the selection criteria as many applications use many kinds of tags. So, to make an affordable system, it plays an important role. Form: As tags are of different sizes, shapes and materials, therefore it is obvious that the tags which will be used for the specific purpose depends on the packaging used in the product and goods. * Standards: EPC global and the International Standards Organizations (ISO) provide standards for the communications between RFID tags and the readers. Character istics in RFID To understand and appreciate the capabilities of RFID systems, it is important to understand the basic parts, data flow that influences the choice of the systems and practicalities of communicating across the air interface. By taking into consideration the components of RFID systems and the different types of functions within the chain, it is possible to take hold of the important issues that influence the effective application of RFID. Thus, it is important to make a start from the method of communication as how it is achieved and the special techniques involved in the design of this system. The Air Interface and Wireless Communication The air interface describes the way in which a tag communicates with the reader. Having knowledge about the tags air interface, we can determine tags read and identity readers compatible with the tag. Communication of data between tags and a reader is done by the wireless communication. For this purpose, there are two methods which can be distinguished from each other, the first one is based on proximity and electromagnetic which is also known as inductive coupling and the other is based on the propagation of electromagnetic waves. Coupling is done via antenna structures that form an integral feature in both tags and readers. The term antenna is basically used for the propagation systems and is applied to the inductive systems. Carrier Frequencies In wired communication systems, the physical wiring constraints allow ommunication links and networks to be effectively isolated from each other and this approach is adopted for radio frequency communication channels. This requires and is generally covered by the government legislations with different parts of electromagnetic spectrums being assigned for different purposes. Not all the countries in the world have access to all the freque ncies which are listed in the table below as some countries have assigned these bands to other users. Within each country and frequency, these are some specific regulations that govern the use of these frequencies. Range and Power Levels The range that can be achieved in RFID system is determined by: * The power which is available at the reader to communicate with the tag * The power available within the tag to respond * The environmental conditions and structures, including signal to noise ratio. Although the level of power is the first determinant of the range, the manner and the efficiency in which the power is deployed also influence the range. The field from the antenna extends into space which surrounds its place and its strength diminishes with respect to its distance. Therefore, strength of the field always reduced to the square of its distance. The power within the tag is generally a lot less than in the reader. In some systems, the reader comprises of the receiver and is separate from the transmitter. As it is possible to choose power levels for different applications, there are some restrictions on its frequencies and constraints on power levels. Although 100 – 500 m W are values which are often quoted in many countries but these values can be confirmed from the authorities for its use. Types of Keying The term keying comes from the days of telegraphy when an operator pressed a manual key to make short and long tones. Keying is described which attributes of an analog carrier, the analog carrier can be a wave or a field, may be modulated to represent the 1s and 0s of a digital message. There are 3 main types of the keying which are: Amplitude shift keying (ASK): A type of keying that sends digital data over analog carriers by changing the amplitude of a wave in time with the data stream. Frequency shift keying (FSK): A type of keying that sends changes through the frequency of the wave. Phase shift keying (PSK): A type of keying that sends changes through the distance by which the waves lead or follow a reference point in time. Coupling A tags coupling mechanism determines the way a circuit on the tag and a circuit on the reader influences each other to send and receive information on power. The type of coupling a tag uses directly affects the range between the tag and the reader. Along with the range, the choice of coupling mechanism strongly affects the frequency which is used by the tag. Some of the coupling techniques are describes which are described below: Backscatter coupling This technique provides an elegant solution to the puzzle of how to make an RFID tag without the battery. This describes that the RF waves transmitted by the reader are spread out by the tag, so waves are bounced back to the source to send a signal. As the term describes, it means that the tags are reflect at the same frequency emitted by the readers, but some of the qualities of the reflection are changed during all this process. But this is the distinguishing feature of this method that both the tags and the readers use the same frequency. Therefore, this is a half duplex communication mode. The reader powers the tag even when the reader is waiting for the signal or sending from itself. Some components of the tag used in this kind of coupling are shown below: Inductive coupling Inductive coupling is a common type of remote coupling. In technical terms, inductive coupling is the transfer of energy from one circuit to another by virtue of the mutual inductance between the circuits. In an RFID system that uses inductive coupling, the reader antenna and the tag antenna each have a coil, which together form a magnetic field. The tag draws energy from the field. The microchip uses this energy to change the electrical load on the tag antenna. These changes are picked up by the reader antenna and converted into a unique serial number. [40] For this reason, it is sometime called transformer coupling. Magnetic coupling It is close to inductive coupling because the reader and tag form a pair of transformer coils. In this coupling, the reader coil is round or u shaped ferrite core with windings on it. Tag must be within 1 cm when operational and placed over the gaps in the core. As the distance is so small, therefore ASK modulation is used due to strong strength of magnetic coupling to make it simple. Tags are inserted in the reader as they can power up the chips which are complex. This is the reason they are ideal to be used in smart cards. Capacitive coupling It is another form of close coupling that works best for the systems in which tags are inserted in the reader. It is also used for the smart cards. Capacitive coupling dispense with antennas and replace them with electrodes. The reader and tag have conductive patches and they work together with a capacitor when held exactly parallel to each other without touching. It uses simple ASK with load modulation to transfer data. Storage and Processing Capacity Information storage and processing capacity is the final and major consideration when choosing a tag. There are many ranges of tags which can store information according to their capability. The simplest one is the tag that can store 1 bit only. On this basis, the presence and absence of an object or an individual is identified. On the other hand, some tags can store KB of data. Larger capacities usually require active tags and even among passive tags. Larger memory capacity directly increases the cost of the tag. 43] Some of the types of tags are as follows: One -bit EAS tags Electronic article surveillance (EAS) tags are typically used to prevent thefts in libraries and mostly markets. EAS tags are called 1 bit tag as they are capable to store 1 bit of the information whether tag is present or not. This is the reason they are mostly used as they are inexpensive and simple. They do not have microchips are always passive using a specific modulation whi ch is appropriate to the coupling that may be recognized by the reader. Surface acoustic wave tags (SAW) In between the 1 bit tag and other, more advanced tags are SAW tags, which operate in microwave range as the backscatter tags and have no processors. They can be encoded at the time of manufacture to contain a number. A saw tag is shown in the figure given below: The antenna at left receives microwaves pulses from the reader and feeds them back to the transducer, which contains a piezoelectric crystal that vibrates when it receives the pulses and this vibration creates an acoustic waves that travels through the tag, encountering reflecting strips. The strips reflect back part of the waves, causing the crystal to vibrate again and creating a reflection. The number of the strips and the distance between them determines the timing and number of the pulses sent back to the reader. Since the number is set at the manufacture time, SAW tags are read only as they have no logic circuits. These tags respond to the pulses at the same time causing the problems to the readers, in sorting out where one tag response starts and another stop. At the time of the writing, practical size also limits these tags to a 32- bit capacity. [45] State machines and microprocessors Some tags are more complex as they have logic circuits in them. Many others tags like 1bit tags and SAW tags have no circuits. The state machines allow these tags to participate in a complex process of anti-collision with the reader. [45] More complicated processors can provide security through encryption or through the control sensors built in the chips. Advanced smart cards even have powerful processors that can be programmed and reprogrammed. As with the memory capacity, more capacity gain means higher will be the cost. The best principle is Dont buy more than you need. Fortunately, even the most advanced tags are dropping in prices as production volume increases. [45] Interrogators RFID interrogators are essentially small computers. They are also composed of roughly three parts: an antenna, an RF electronics module, which is responsible for communicating with the RFID tag, and a controller electronics module, which is responsible for communicating with the controller. An RFID interrogator acts as a bridge between the RFID tag and the controller and has just a few basic functions which are: * Read the data contents of an RFID tag * Write data to the tag (smart cards only) Relay data to and from the controller * Power the tag (passive tags only) In addition to performing the four basic functions above, more complex RFID interrogators are able to perform three more critical functions: * implementing anti-collision measures to ensure simultaneous RW communication with many tags, * authenticating tags to prevent fraud or unauthorized access to the syste m, * Data encryption to protect the integrity of data. [47] Types of Interrogators Different readers are for different purposes as they fit for different occasions. They differ in size and shapes, support various protocols and requirements. Some readers are half an inch across to the the size of a computer desk. Some readers conform to the same standards as the tags read, but some can support multiple protocols or the tags protocols made by the vendors only. The most important of all is the power levels, frequency variations and requirements vary from region to region. Interrogators Placement RFID systems do not require line of sight between tags and readers the way that bar code systems do. As a result of this, system designers have much more freedom when deciding where to place interrogators Readers and antennas can be placed in variety of places for different purposes. These categories are as follows: Portals The word portal means doorways or the entrance. In this category, they are placed where they can recognize tagged items entering or leaving the place. It is common setup for the warehouses. Tunnels It can be useful for the assembly lines as the readers may identify the station when an item is currently passing through. Handhelds These readers work in a place where the items are heavy enough and they cannot be moved near the readers. They can communicate with the help of wireless Ethernet or RF modem. Forklift readers In some workplaces these readers are now placed on the forklifts as a person might carry a handheld reader. Smart shelves It is potentially made for the real time inventory of the stocks in the workplaces. Smart shelves are the units where antennas are incorporated in a way that readers can acknowledge whether item is coming or departing from the shelves. RFID Controllers RFID controllers are the brains of any RFID system. They are used to network multiple RFID interrogators together and to centrally process information.