Thursday, March 19, 2020

AOL Time Warner essays

AOL Time Warner essays On January 10, 2000, one of the largest, most powerful mergers was announced to the world. Media giant Time Warner will join forces with the Internet superstar, America on Line. The $183 billion dollar deal is the biggest in history. In the recent past, there has been a wave of merger-mania, both in the United States and in Europe. The merger of the Millennium is between America on Line and Time Warner. The AOL Time Warner deal represents the joining of the Old Media with the New Media. Not only is it a marriage of different approaches, the two CEO's are very diverse individuals. The two companies are quite different, in nearly every aspect. Some of the divisions of Time Warner have been around since the 1920's, while the youngster, AOL is a mere fifteen years old. The quick paced, new up starting Internet companies never thought in a million years they would ever need the old stand-by media organizations. "The Internet will revolutionize everything", that is what their beliefs were. They were fearless and believed themselves to be invincible, but things have changed. The Internet has put the world only a mouse click away and it has changed the world. The fact of the matter is the world of the Internet is extremely competitive and in order to survive, you must invest huge sums into your marketing cam paign, in some cases up to seventy percent of a budget. The one thing that you can always could on in this word is change, and there are going to be some major changes in the realm of the high tech companies. The 'techies' are going to have to realize their need for and have to learn how to form lasting relationships with the 'old stand bys' in order to keep up with today's world. Time Warner is, for the most part, a stable reliable organization. Time Warner's holdings include many magazines, Time, Sports Illustrated, Money and Fortune just to name a few. Time Warner also possesses Warner Brothers Studio, Warner Mu...

Tuesday, March 3, 2020

Should I Take the PSAT as a Freshman

Should I Take the PSAT as a Freshman SAT / ACT Prep Online Guides and Tips It's never too early to start planning! When should you start preparing to apply tocollege? When you sign up for the SAT? The day you choose your freshman year classes? From the time you learn to read your first picture book? This might be a matter of debate between you and your parents, but we can all agree that planning starts long before you actually start filling out applications. So to put yourself on the track for college success, should you start freshman year off by taking the PSAT? First, what exactly is the PSAT for? Understanding this will let us see whether it suits your needs as a freshman. The PSAT Is For... National Merit Distinctions and Scholarships The PSAT is administered by the National Merit Scholarship Corporation, or the NMSC. Based on your scores, the NMSC may award you distinctions like Commended Scholar, Semifinalist, or Finalist. Students in the top 1% might even win scholarships. Only high school juniors are eligible for NMSC awards. So your freshman year score, even if it's perfect, unfortunately can't count for National Merit. However, prepping and getting a practice run or two in before junior year can only improve your score, especially if you're aimingto make it into the top 1%. I strongly recommend takingthe PSAT in at least sophomore year to get in your trial run. As for freshman year? It can definitely be helpful, but it's also pretty early. You might be served just as well by focusing on your schoolwork, developing your academic skills, and doing test prep on your own for the next year. If you want to take the PSAT in 9th grade, then any real test experience can be valuable and help you score higher thenext time. Besides NMSC awards, the PSAT is helpful for another important test... Good Practice for the SAT The "P" in PSAT actually stands for "preliminary," not "practice," but this common misconception isn't too far from the truth. The new PSAT starting in 2015 is closely aligned to the content and types of questions you'll see on the new SAT. Both test your understanding of math, Critical Reading, and writing (though the PSAT does not have an essay component). Both testsfocus on determining meaning in context, whether it's analyzing a passage or interpreting data from a graph. Prepping for and taking the PSAT will help you develop the valuable skills you need to score highly on the SAT. It also helps you pace yourself under strict time limits and apply guessing strategies, like process of elimination. Both the new PSAT and new SAT feature multiple choice questions with 4 answer choices instead of the current 5, and neither has penalties for wrong answers. In addition to testing similar skills as the SAT, the PSAT helps you predict how you'll score on the SAT. The new PSAT is scored on a scale between 320 and 1520, with a range of 160 to 760 for Math and the same for Reading and Writing. The new SAT will be scored out of 1600, with a range of 200 to 800 for Math and the same for Reading and Writing. These scales are very similar, with the PSAT scores shifted down to account for the fact that it's a somewhat easier test than the SAT. How you do on the PSAT helpspredict how you'll do on the SAT, with the knowledge that the SAT is somewhat more challenging. Not onlycan you use your PSAT score as a predictor of how you are likely to score on the SAT, you can alsouse it to set goals and up your target scores. Because of this, it can only help you to begin to get familiar with the PSAT freshman year, as scoring well on these tests is all about practice and preparation. But again, it's up to you whether taking the official PSAT or simply practicing on your own, like with PSAT practice test pdfs, is most beneficial freshman year. Finally, the PSAT can put you in touch with colleges... To Connect With Colleges To state the obvious, the PSAT and SAT are tests that prepare you for applying to and succeeding in college.The PSAT can be helpful for providing your contact information to colleges (with your permission) so they can get in touch with you and share information about their campus events, deadlines, and scholarships. If you want to put yourself on colleges' radar early, then taking the PSAT may be one way to do this. Another way would be indicating interest through their individual websites. Now that you understand the various uses and applications of the PSAT, what's the final verdict: should you take the PSAT as a freshman? Final verdict? Should You Take the PSAT In 9th Grade? Freshman year is early to worry too much about the PSAT, but if you have the means and motivation, every real test is valuable experience. You'll get a sense of real testing conditions, along with an official score report that can help you set goals and design your study plan for next time. If you decide to take the PSAT in 9th grade, you'll want to talk to your school counselor about it. Juniors are usually automatically signed up for it through the school, but freshmen usually need to ask to register specifically. If you decide to skip the test for now, you'll be served well by taking practice tests and self-studying. That way, you can prep to take the PSAT as a sophomore and then be in great shape junior year, when it counts for National Merit. Want to get a head start on the PSAT NMQST? We have the industry's leading PSAT prep program. Built by Harvard grads and SAT full scorers, the program learns your strengths and weaknesses through advanced statistics, then customizes your prep program to you so that you get the most effective prep possible. Check out our 5-day free trial today: While you may or may not take the PSAT freshman year, you might want to consider taking an SAT Subject Test at the end of freshman year. The Subject Tests measure your mastery in a subject like Biology or Math. Depending on what courses you've taken, you may be prepared and have the content fresh in your mind as ninth grade draws to a close. Check out other considerations and SAT Subject Test dates here. Besides the PSAT, are there any other things you should focus on freshman year? Freshman Year Focus: The Essentials Colleges look at all four years of high school, whether it's the courses you select, your academic performance, your extracurricular and community involvement, or your summer activities. Colleges also love to see your involvement in a particular area deepen and develop into an area of expertise or leadership position. Admissions officers understand exploration freshman year, but they generally like to see commitment over the long run. To that end, it's a good idea to try out clubs and activities in freshman year and find ones in whichyou can not only make progress, but that might also put you in a position for leadershipor an internship later on in high school. It's also a smart move to challenge yourself in college prep and honors classes. Make sure you'll be taking Algebra and Geometry by the time you take the SAT. If you're interested in the ACT or the Math 2 Subject Test, then you also will need to have some understanding of precalculus and trigonometry. If you're reading about taking the PSAT as a freshman, then you're probably well aware of the power of prep when it comes to the PSAT and SAT. You're giving yourself a goodamount of time to get ready through studying, as well as developing critical reading, writing, and math skills in and out of the classroom. Some students even sit for the official SAT as freshmen as part of their study plan, to gauge their level and achieve a good 9th grade SAT score. Bystaying active and aware, you're already preparing to apply to college. Or maybe you've been preparing since you learned to read your first picture book! What's Next? How exactly is the PSAT scored? Check out this guide on what your PSAT score means, and the 3 steps you should take after the PSAT. Early studying is smart studying for the SAT. Learn why and how to start prepping well in advance of SAT test day. Are you taking the SAT as a sophomore? If you're scoring these scores, then you're in a good position for next year. Read about good 10th grade SAT scores and how to improve them even more. Want to improve your SAT score by 160 points? Check out our best-in-class online SAT prep program. We guarantee your money back if you don't improve your SAT score by 160 points or more. Our program is entirely online, and it customizes your prep program to your strengths and weaknesses. We also feature thousands of practice questions, 10 official SAT practice tests, and personal feedback on your essays from an expert instructor. Check out our 5-day free trial:

Saturday, February 15, 2020

The case method of stratigic analysis David and Goliath Essay

The case method of stratigic analysis David and Goliath - Essay Example -There are a number of possible solutions to the problem. One solution is to have each side choose its strongest member. For the Philistine this would be Goliath. For the Israelites this would be David. Both individuals would then fight to the death. The winner would determine the resolution for the entirety of their population. While this would provide a resolution and avoid significant death, one recognizes that it is largely an arbitrary means of deciding on the solution; for this reason not all participants may be happy with the final solution. -Another potential option would be to have both organizations engage in diplomacy. While a regular component of international relations in the contemporary environment, during the time of this conflict such actions occurred only in limited form. This then constitutes a major potential option a means of solving this conflict. -Still, another potential option would be to allow both armies to engage in warfare. While this is the most extreme solution it is an option that continues to be implemented through the contemporary world environment. This solution would be effective in providing a strong and resolute answer to the issue, as the stronger party would have the final say in the matter. Still, the human death toll would be significant. One considers that diplomacy functions as the best option as it determines an amenable solution without bloodshed and death. This approach functions within the Ansoff management techniques. One considers that turbulence is a prominent area of concern within the Ansoff approach, and this situation demonstrates a great degree of unpredictability. Ansoff recognizes that managers must meet these challenges with an appropriate aggressiveness of strategy. In this sense, the diplomatic approach recognizes that because of the turbulent nature of the situation, a strong and resolute solution needs to be reached. The diplomatic action then will

Sunday, February 2, 2020

Modern Microecon, Consumer Theory Essay Example | Topics and Well Written Essays - 2000 words

Modern Microecon, Consumer Theory - Essay Example In raw economic terms, utility is a measure of consumer satisfaction, that is, how much satisfaction a consumer derives from the consumption of a good or a service. Budget constraint on the other hand represents the combination of goods or services an individual can consume or purchase in consideration to given prices with his or her limited income. Combining the two concepts forms the foundation of consumer theory. The utility theory provides a methodological framework whereby usually, all individuals, organizations and firms evaluate given options. Utility is a term used to describe the satisfaction that each of the given options provide to the one making the decision. Hence, the basis of the utility theory is that each individual will choose that option which tends to maximize utility, working on what is called the ‘maximization principle’. This principle states that the most desirable choice is the one with the highest level of satisfaction. However, while making the se decisions, the individual must also consider his income earned along with the respective prices of the goods and services in question. ... Total utility continuously rises as consumption increases. This rise becomes smaller as more units of a product are consumed, it can also decline after a certain level of consumption. On the other hand, marginal utility measures the change in consumption benefit as a result of consuming one more or one less unit of a product. In other words, marginal utility tracks the change in total utility as the number of units consumed changes. The behavior of marginal utility is such that it tends to fall continuously as consumption of a product increases. This is because the first few units consumed of a product provide a higher level of satisfaction than the later few. For example, the first drink of water is worth a lot more to a thirsty individual than his seventh one. For a consumer to be in equilibrium certain conditions need to be met. The consumers are assumed to be rational in their decision whereby they aim to maximize the utility derived from the consumption of any product. It is als o assumed that consumers have limited incomes and that the value of utility can be quantified in monetary terms. The equi-marginal principle states that a consumer will be in equilibrium if it is not possible to switch expenditure from good X in favour of good Y to achieve an increase in total utility. In other word this principle is satisfied when the marginal utility of every dollar spent on a good is equal to the price paid for that good. If a basket of goods is in question, an individual will continue to alter the mix of consumption of the products until the marginal utility of a dollar spent on each of the goods is equal. Therefore, the equilibrium principle can be expressed as MUx/Px=MUy/Py, where MU is the marginal utility and P is the price of the good. Consumer

Saturday, January 25, 2020

Dissociative Amnesia- Memory Loss Essay -- short term memory, American

Introduction: The main Character is Lenard; he is an average looking male in his mid to early thirties. At first look one would never think that there is anything wrong with him, he speaks clearly and intelligently, id s polite individual and well-mannered when interacting with others. Lenard does the typical things and daily activities that a normal person does. On sight one can’t tell that, but Lenard has a condition where he cannot recall anything that happens to him within a matter of minutes, things such as people he meets, the conversations he had and places he’s been become distant after a few minutes. The only thing that Lenard is able to remember is those things that happened before the incident that caused his diagnosis. The things that Lenard is able to recall are those things such as his name, who he is, and the way his life was before the traumatic experience. Lenard is incapable of making new memories as well as short term memories. Diagnosis: In the film Lenard tells people that he has short term memory loss, this isn’t the case though, Lenard’s disorder is in fact more serious then he knows. Lenard has; individuals who have this condition like Lenard have difficulties remembering parts of their lives from a single event or numerous events that have occurred. Dissociative amnesia typically occurs when a traumatic event happens in that individual’s life. For Lenard, the traumatic event that occurred in his life was the rapping and murder of his wife which occurred in their own house while Lenard was asleep, then awoke to see what was going on, to which he was hit across the head with a gun which caused his condition, then left laying besides his lifeless wife on the bathroom floor, Symptoms & Axis I-V: The DSM... he encountered didn’t occur. Works Cited: DSM-IV-TR. (n.d.). American Psychiatric Association. Memento. Dir. Christopher Nolan. Landmark, 2000. DVD. Merriam-Webster. (n.d.). Etiology. Retrieved November 9, 2013 from Merriam- Webster: NCBI. (n.d.) Us National Library of Medicine National Institute of Health. Retrieved November 9, 2013, from PubMed: Psychotherapy And Counseling. (n.d.). Dissociative Amnesia – DSMIV Definition. Retrieved November 9, 2013, from the DSM IV: category/dissociative-amnesia Whitbourne, S. K., & Haligan, R. P. (2013). Abnormal Psychology: Clinical Perspectives on Psychological Disorders, Seventh Edition. New York, NY: McGraw-Hill.

Friday, January 17, 2020

Smart Material

â€Å"SMART MATERIALS† ABSTRACT The world has undergone two materials ages, the plastics age and the composite age, during the past centuries. In the midst of these two ages a new era has developed. This is the smart materials era. According to early definitions, smart materials are materials that respond to their environments in a timely manner. The definition of smart materials has been expanded to materials that receive, transmit or process a stimulus and respond by producing a useful effect that may include a signal that the materials are acting upon it. Smart materials cover a wide and developing range of technologies.A particular type of smart material, known as chromogenics, can be used for large areaglazing in buildings, automobiles, planes, and for certain types of electronic display. Smart materials have been around for many years and they have found a large number of applications. There are many types of the materials present some of them listed below: Shape memory alloy 2) Piezoelectric materials 3) Magnetostrictive materials 4) Magneto- and electro-rheological materials 5) Chromic materials Due to the property of responding quickly with environment and many applications in daily life smart materials deserve a great future scope.I. INTRODUCTION Smart materials have been around for many years and they have found a large number of applications. The use of the terms ‘smart' and ‘intelligent' to describe materials and systems came from the US and started in the 1980? s despite the fact that some of these so-called smart materials had been around for decades. Many of the smart materials were developed by government agencies working on military and aerospace projects but in recent years their use has transferred into the civil sector for applications in the construction, transport, medical, leisure and domestic areas.The first problem encountered with these unusual materials is defining what the word† smart? actually means. One di ctionary definition of smart describes something which is a stute or ‘operating as if by human intelligence' and this is what smart materials are. A and back again when you return inside. This coating is made from a smart material which is described as being photochromic. There are many groups of smart materials, each exhibiting particular properties which can be harnessed in a variety of high-tech and everyday applications. These include shape memory smart material is one which reacts to its environment aby itself.The change is inherent to the material and not a result of some change in volume, a change in colour or a change in viscosity and this may occur in response to a change in temperature, stress, electrical current, or magnetic field. In many cases this reaction is reversible, a common example being the coating on spectacles which reacts to the level of UV light, turning your ordinary glasses into sunglasses when you go outside alloys, piezoelectric materials, magneto- rheological and electro-rheological materials, magnetostrictive materials and chromic materials which change their colour in reaction to various stimuli.The distinction between a smart material and a smartstructure should be emphasised. A smart structure incorporates some form of actuator and sensor (which may be made from smart materials) with control hardware and software to form a system which reacts to its environment. Such a structure might be an aircraft wing which continuously alters its profile during flight to give the optimum shape for the operating conditions at the time. II SHAPE MEMORY ALLOYS Shape memory alloys (SMAs) are one of the most well known types of smart material and they have found extensive uses in the 70 years since their discoveryWhat are SMAs? A shape memory transformation was first observed in 1932 in an alloy of gold and cadmium, and then later in brass in 1938. The shape memory effect (SME) was seen in the gold-cadmium alloy in 1951, but this was of li ttle use. Some ten years later in 1962 an equiatomic alloy of titanium and nickel was found to exhibit a significant SME and Nitinol (so named because it is made from nickel and titanium and its properties were discovered at the Naval Ordinance Laboratories) has become the most common SMA.Other SMAs include those based on copper (in particular CuZnAl), NiAl and FeMnSi, though it should be noted that the NiTi alloy has by far the most superior properties. How do SMAs work? The SME describes the process of a material changing shape or remembering a particular shape at a specific temperature (i. e. its transformation or memory temperature). Materials which can only exhibit the shape change or memory effect once are known as one way SMAs. However some alloys can betrained to show a two-way effect in which they remember two shapes, one below and one above the memory temperature.At the memory temperature the alloy undergoes a solid state phase transformation. That is, the crystal structur e of the material changes resulting in a volume or shape change and this change in structure is called a„thermoelastic martensitic transformation?. This effect occurs as the material has a martensitic microstructure below the transformation temperature, which is characterised by a zig-zag arrangement of the atoms, known as twins. The martensitic structure is relatively soft and is easily deformed by removing the twinned structure.The material has an austenitic structure above the memory temperature, which is much stronger. To change from the martensitic or deformed structure to the austenitic shape the material is simply heated through the memory temperature. Cooling down again reverts the alloy to the martensitic state as shown in Figure 1. The shape change may exhibit itself as either an expansion or contraction. The transformation temperature can be tuned to within a couple of degrees by changing the alloy composition.Nitinol can be made with a transformation temperature an ywhere between –100? C and +100? C which makes it very versatile. Where are SMAs used? Shape memory alloys have found a large number of uses in aerospace, medicine and the leisure industry. A few of these applications are described below. Medical applications Quite fortunately Nitinol is biocompatible, that is, it can be used in the body without an adverse reaction, so it has found a number of medical uses. These include stents in which rings of SMA wire hold open a polymer tube to pen up a blocked vein , blood filters, and bone plates which contract upon transformation to pull the two ends of the broken bone in to closer contact and encourage more rapid healing . It is possible that SMAs could also find use in dentistry for orthodontic braces which straighten teeth. The memory shape of the material is made to be the desired shape of the teeth. This is then deformed to fit the teeth as they are and the memory is activated by the temperature of the mouth. The SMART exerts enou gh force as it contracts to move the teeth slowly and gradually.Surgical tools, particularly those used in key hole surgery may also be made from SMAs. These tools are often often bent to fit the geometry of a particular patient, however, in order for them to be used again they return to a default shape upon sterilisation in an autoclave. Still many years away is the use of SMAs as artificial muscles, i. e. simulating the expansion and contraction of human muscles. This process will utilise a piece of SMA wire in place of a muscle on the finger of a robotic hand.When it is heated, by passing an electrical current through it, the material expands and straightens the joint, on cooling the wire contracts again bending the finger again In reality this is incredibly difficult to achieve since complex software and surrounding systems are also required. Figure 1 – Change in structure associated with the shape memory effect. NASA have been researching the use of SMA muscles in robots which walk, fly and swim! Domestic applications SMAs can be used as actuators which exert a force associated with the shape change, and this can be repeated over many thousands of cycles.Applications include springs which are incorporated in to greenhouse windows such that they open and close themselves at a given temperature. Along a similar theme are pan lids which incorporate an SMA spring in the steam vent. When the spring is heated by the boiling water in the pan it changes shape and opens the vent, thus preventing the pan from boiling over and maintaining efficient cooking. The springs are similar to those shown in Figure 5. SMAs can be used to replace bimetallic strips in many domestic applications.SMAs offer the advantage of giving a larger deflection and exerting a stronger force for a given change in temperature. They can be used in cut out switches for kettles and other devices, security door locks, fire protection devices such as smoke alarms and cooking safety indicato rs (for example for checking the temperature of a roast joint). Aerospace applications A more high tech application is the use of SMA wire to control the flaps on the trailing edge of aircraft wings.The flaps are currently controlled by extensive hydraulic systems but these could be replaced by wires which are resistance heated, by passing a current along them, to produce the desired shape change. Such a system would be considerably simpler than the conventional hydraulics, thus reducing maintenance and it would also decrease the weight of the system. Manufacturing applications SMA tubes can be used as couplings for connecting two tubes. The coupling diameter is made slightly smaller than the tubes it is to join. The coupling is deformed such that it slips over the tube ends and the temperature changed to activate the memory.The coupling tube shrinks to hold the two ends together but can never fully transform so it exerts a constant force on the joined tubes. Why are SMAs so flexibl e? In addition to the shape memory effect, SMAs are also known to be very flexible or super elastic, which arises from the structure of the martensite. This property Of SMARTs has also been exploited for example in mobile phone aerials, spectacle frames and the underwire in bras. The kink resistance of the wires makes them useful in surgical tools which need to remain straight as they are passed through the body.Nitinol can be bent significantly further than stainless steel without suffering permanent deformation. Another rather novel application of SMAs which combines both the thermal memory and super elastic properties of these materials is in intelligent fabrics. Very fine wires are woven in to ordinary polyester cotton fabric. Since the material is super elastic the wires spring back to being straight even if the fabric is screwed up in a heap at the bottom of the washing basket! So creases fall out of the fabric, giving you a true non-iron garment!In addition the wires in the s leeves have a memory which is activated at a given temperature (for example 38 C) causing the sleeves to roll themselves up and keeping the wearer cool. PIIEZOELECTRIIC MATERIIALS The piezoelectric effect was discovered in 1880 by Jaques and Pierre Curie who conducted a number of experiments using quartz crystals. This probably makes piezoelectric materials the oldest type of smart material. These materials, which are mainly ceramics, have since found a number of uses. What is the piezoelectric effect?The piezoelectric effect and electrostriction are opposite phenomena and both relate a shape change with voltage. As with SMAs the shape change is associated with a change in the crystal structure of the material and piezoelectric materials also exhibit two crystalline forms. One form is ordered and this relates to the polarisation of the molecules. The second state is nonpolarised and this is disordered. If a voltage is applied to the non-polarised material a shape change occurs as th e molecules reorganise to align in the electrical field. This is known as electrostriction.Conversely, an electrical field is generated if a mechanical force is applied to the material to change its shape. This is the piezoelectric effect. The main advantage of these materials is the almost instantaneous change in the shape of the material or the generation of an electrical field. What materials exhibit this effect? The piezoelectric effect was first observed in quartz and various other crystals such as tourmaline. Barium titanate and cadmium sulphate have also been shown to demonstrate the effect but by far the most commonly used piezoelectric ceramic today is lead zirconium titanate (PZT).The physical properties of PZT can be controlled by changing the chemistry of the material and how it is processed. There are limitations associated with PZT; like all ceramics it is brittle giving rise to mechanical durability issues and there are also problems associated with joining it with ot her components in a system. Where are piezoelectric materials used? The main use of piezoelectric ceramics is in actuators. An actuator can be described as a component or material which converts energy (in this case electrical) in to mechanical form.When a electric field is applied to the piezoelectric material it changes its shape very rapidly and very precisely in accordance with the magnitude of the field. Applications exploiting the electrostrictive effect of piezoelectric materials include actuators in the semiconductor industry in the systems used for handling silicon wafers, in the microbiology field in microscopic cell handling systems, in fibre optics and acoustics, in ink-jet printers where fine movement control is necessary and for vibration damping.The piezoelectric effect can also be used in sensors which generate an electrical field in response to a mechanical force. This is useful in damping systems and earthquake detection systems in buildings. But the most well know n application is in the sensors which deploy car airbags. The material changes in shape with the impact thus generating a field which deploys the airbag. A novel use of these materials, which exploits both the piezoelectric and electrostrictive effects, is in smart skis which have been designed to perform well on both soft and hard snow. Piezoelectric sensors detect vibrations (i. e. he shape of the ceramic detector is changed resulting in the generation of a field) and the electrostrictive property of the material is then exploited by generating an opposing shape change to cancel out the vibration. The system uses three piezoelectric elements which detect and cancel out large vibrations in real time since the reaction time of the ceramics is very small . By passing an alternating voltage across these materials a vibration is produced. This process is very efficient and almost all of the electrical energy is converted into motion. Possible uses of this property are silent alarms for pagers which fit into a wrist watch.The vibration is silent at low frequencies but at high frequencies an audible sound is also produced. This leads to the concept of solid state speakers based on piezoelectric materials which could also be miniaturised. Do polymers exhibit these effects? Ionic polymers work in a similar way to piezoelectric ceramics, however they need to be wet to function. An electrical current is passed through the polymer when it is wet to produce a change in its crystal structure and thus its shape. Muscle fibres are essentially polymeric and operate in a similar way, so research in this field has focussed on potential uses in medicine. ature of the piezoelectric effect making them invaluable for the niche applications which they occupy. MAGNETOSTRIICTIIVE MATERIIALS Magnetostrictive materials are similar to piezoelectric and electrostrictive materials except the change in shape is related to a magnetic field rather than an electrical field. What are magnetost rictive materials? Magnetostrictive materials convert magnetic to mechanical energy or vice versa. The magnetostrictive effect was first observed in 1842 by James Joule who noticed that a sample of nickel exhibited a change in length when it was magnetised.The other ferromagnetic elements (cobalt and iron) were also found to demonstrate the effect as were alloys of these materials. During the 1960s terbium and dysprosium were also found to be magnetostrictive but only at low temperatures which limited their use, despite the fact that the size change was many times greater than that of nickel. The most common magnetostrictive material today is called TERFENOL-D (terbium (TER), iron (FE), Naval Ordanance Laboratory (NOL) and dysprosium (D)). This alloy of terbium, iron and dysprosium shows a large magnetostrictive effect and is used in transducers and actuators.The original observation of the magnetostrictive effect became known as the Joule effect, but other effects have also been ob served. The Villari effect is the opposite of the Joule effect, that is applying a stress to the material causes a change in its magnetization. Applying a torsional force to a magnetostrictive material generates a helical magnetic field and this is known as the Matteuci effect. Its inverse is the Wiedemann effect in which the material twists in the presence of a helical magnet field.How do magnetostrictive materials work? Magnetic materials contain domains which can be likened to tiny magnets within the material. When an external magnetic field is applied the domains rotate to align with this field and this results in a shape change as. Conversely if the material is squashed or stretched by means of an external force the domains are forced to move and this causes a change in the magnetisation. Where are magnetostrictive materials used? Magnetostrictive materials can be used as both actuators (where a magnetic ield is applied to cause a shape change) and sensors (which convert a move ment into a magnetic field). In actuators the magnetic field is usually generated by passing an electrical current along a wire. Likewise the electrical current generated by the magnetic field arising from a shape change is usually measured in sensors. Early applications of magnetostrictive materials included telephone receivers, hydrophones, oscillators and scanning sonar. The development of alloys with better properties led to the use of these materials in a wide variety of applications.Ultrasonic magnetostrictive transducers have been used in ultrasonic cleaners and surgical tools. Other applications include hearing aids, razorblade sharpeners, linear motors, damping systems, positioning equipment, and sonar. MAGNETO– AND ELECTRO RHEOLOGIICAL MATERIIALS All of the groups of smart materials discussed so far have been based on solids. However, there are also smart fluids which change their rheological properties in accordance with their environment. What are smart fluids? Th ere are two types of smart fluids which were both discovered in the 1940s.Electro-rheological (ER) materials change their properties with the application of an electrical field and consist of an insulating oil such as mineral oil containing a dispersion of solid particles (early experiments used starch, stone, carbon, silica, gypsum and lime). Magnetorheological materials (MR) are again based on a mineral or silicone oil carrier but this time the solid dispersed within the fluid is a magnetically soft material (such as iron) and the properties of the fluid are altered by applying a magnetic field. In both cases the dispersed particles are of the order of microns in size.How do smart fluids work? In both cases the smart fluid changes from a fluid to a solid with the application of the relevant field. The small particles in the fluid align and are attracted to each other resulting in a dramatic change in viscosity as shown in Figure 7. The effect takes milliseconds to occur and is com pletely reversible by the removal of the field. Figure 8 clearly shows the effect of a magnet on such an MR fluid. With ER fluids a field strength of up to 6kV/mm is needed and for MR fluids a magnetic field of less than 1Tesla is needed. Where are smart fluids used?Uses of these unusual materials in civil engineering, robotics and manufacturing Electrodes Suspension fluid Particle Figure 7 – Schematic diagram showing the structure of a electrorheological fluid between two electrodes. The top figure shows the structure in a low field strength where the particles are randomly distributed. When a higher field strength is applied, as in the bottom diagram, the particles align causing a change in the viscosity of the fluid. Figure 8 – A puddle of magnetorheological fluid stiffens in the presence of a magnetic field. courtesy of Sandy Hill / University of Rochester) are being explored. But the first industries to identify uses were the automotive and aerospace industries wh ere the fluids are used in vibration damping and variable torque transmission. MR dampers are used to control the suspension in cars to allow the feel of the ride to be varied. Dampers are also used in prosthetic limbs to allow the patient to adapt to various movements for example the change from running to walking. Future Scope: The future of smart materials and structures is wide open.The use of smart materials in a product and the type of smart structures that one can design are only limited by one’s talents, capabilities, and ability to ‘‘think outside the box. ’’ In an early work5 and as part of short courses there were discussions pertaining to future considerations. A lot of the brainstorming that resulted from these efforts is now being explored. Some ideas that were in the conceptual stage are now moving forward. Look at the advances in information and comforts provided through smart materials and structures in automobiles. Automobiles can b e taken to a garage for service and be hooked p to a diagnostic computer that tells the mechanic what is wrong with the car. Or a light on the dashboard signals ‘‘maintenance required. ’’ Would it not be better for the light to inform us as to the exact nature of the problem and the severity of it? This approach mimics a cartoon that appeared several years ago of an air mechanic near a plane in a hanger. The plane says ‘‘Ouch’’ and the mechanic says ‘‘Where do you hurt? ’’ One application of smart materials is the work mentioned earlier of piezoelectric inkjet printer that serves as a chemical delivery to print organic light-emitting polymers in a fine detail on various media.Why not take the same application to synthesize smaller molecules? With the right set one could synthesize smaller molecules in significant amounts for characterization and evaluation and in such a way that we could design experiments with relative ease. A new class of smart materials has appeared in the literature. This is the group of smart adhesives. We previously mentioned that PVDF film strips have been placed within an adhesive joint to monitor performance. Khongtong and Ferguson developed a smart adhesive at Lehigh University. 0 They suggested that this new adhesive could form an antifouling coating for boat hulls or for controlling cell adhesion in surgery. The stickiness of the new adhesive can be switched on and off with changes in temperature. The smart adhesive also becomes water repellent when its tackiness wanes. 50 The term ‘‘smart adhesive’’ is appearing more frequently in the literature. A topic of research that was in the literature a few years ago was ‘‘smart clothes’’ or ‘‘wearable computers’’ being studied at MIT. The potential of this concept is enormous. This sounds wonderful as long as we learn how to work smart er, not longer.CONCLUSION: From the abilities of the smart material to respond the environmental changes the conclusion arises that ‘‘smart’’ in the name do not meet the definition of being smart, that is, responding to the environment in a reversible manner. Due to their properties they must deserve a great future. REFERENCES [1]Mechanical Engineers’ Handbook: Materials and Mechanical Design, Volume 1, Third Edition. Edited by Myer Kutz. [2]www. memorymetals. co. uk [3] www. nitinol. com [4] www. sma-inc. com [5]www. cs. ualberta. ca/~database/MEMS/sma_mems/sma. html [6]http://virtualskies. arc. nasa. gov/research/youdecide/Shapememalloys. html