E-commerce and M-commerce Essay Example | Topics and Well Written Essays - 3000 words

E-commerce and M-commerce - Essay Example If E-commerce and M-commerce matters for development, it is not because the are the fancier or more convenient ways of doing shopping: but they allows allow enterprises to operate efficiently with their trading partners including their production sites, vendors and point of sales. For an Internet user to become an e-commerce customer, a much higher frequency of access is necessary in order to acquire the familiarity with the e-business transactions and payment systems. This is more required for the B2B traders, where the order of magnitude of their exposure to Internet etiquette must be more than a normal user. Contradicting the above general assumption, a survey conducted by IDC in 2002 there is a gap found between the Internet users and e-commerce revenue in the developing and developed countries. This shows that the usage of Internet does not directly imply the e-business attitude. Where as, the M-Commerce does not necessarily require more adequacy of such involvement with the mobile devise or operating the m-commerce applications. The reason behind this could be attributed to the low involvement and less choice of options for the customer to choose between while buying something through mobile phone. In other terms, mobile commerce involves a quick decision for buying, by simply replying to the message alert for the sale offer or saying yes to the chosen option. The prevalence of E-commerce has led people to research and form the strategically options to push the sales through Internet in the recent years. Some researches stated that lower per capita incomes, low credit card usage, lack of relevant Products and service to buy in near places, and lack of logistics and fulfillments are the factors influencing the buying behaviors of the users on E-commerce. Though these should be the same factors influencing the buying behavior of the M-Commerce also, rather than clear evidence of that, one could perceive some thing else alarming that the above for the influence of M-Commerce buying patterns. E-commerce trading is more seen between B2B or Business to Government types of transactions than Business to Consumer. This adoption could be linked with their capacity to integrate themselves into regional and global supply chains. At the enterprise level, this requires being able to meet technological and organizational challenges. At the country level, the digital and the physical layers of the national economies have to be connected in congruence. Thus E-commerce opens more trading between different foreign countries. Where as M-commerce, due to the localized service operators, has the limitation of global restriction with the service options limited within the geographical regions. Beyond technological limitations, the logistics and Policy regulations are also the other factors for this shortage. May be the still future of M-commerce could resolve such type of hindrances in a very short future depending on the nature of service expansions. While looking at the scenario of operations, E-commerce offers a more popular way of shopping than the other, through PC, laptops and palm tops. The purchasers of the Internet

Stainless steel powder metrology Thesis Example | Topics and Well Written Essays - 2000 words

Stainless steel powder metrology - Thesis Example PROCEDURE The mixtures underwent a complete procedure to obtain the results and compare them according to different standards. The procedure of the experiment is explained in detail in this part of the report. Preparation of the Mixture The powder mixture, each specimen separately, is weighed and the weight recorded. The process is initiated after the weighing. The powder is properly mixed using tubes and revolving machine. In these experiments, two different mixtures, ferrous 316L with 1 gram silicon and the same mixture with the addition of 1gm boron is used. The mixtures were then sintered and quenched under different temperature conditions. The sintering has to be discussed briefly to be understood. Sintering and Quenching The specimens prepared are pressurized at 700 MPa and made into round discs as shown in the picture below. . The specimen is heated inside a closed container, to different temperature. As recorded before, there are in total 13 specimens which are used in the ex periment. Each specimen is labeled properly before any kind of experiment us conducted on it. The two mixtures samples of â€Å"A† and â€Å"B† are heated at 1220, 1230, 1235, 1240, 1280, and 1295o C respectively. Each sample was then sectioned, mounted and polished for microscopical examination. These methods are explained in detail in the following part of the report. Sectioning It is essential for maximizing the working parameters since incorrect cutting can waste small samples, which are very difficult to make. The sample with deformation should be given maximum support to un-clamp them (German, 1990). Mounting The samples are too little in size to handle the different steps of the procedure. It is essential for maximizing the working parameters. Therefore a uniform and rounded surface is given to the specimen so that the damage is prevented during grinding and polishing procedures (German, 1990). Grinding The samples are grounded to reach finer surfaces. Grinding is done under stream of water to remove any free particles that are being cut out of the sample and to minimize the eroding effect on the sample and to save its surface from rash cuts. The specimen is then dried out as there was water on it (German, 1990). Polishing It is also a very important part of the experiment. Since for the photography the best surface is required. It is done by rotating a cloth over the surface with the help of a polishing machine. A polishing liquid is also used (German, 1990). Etching The samples need to be etched as the last part of the procedure. But before etching is done, the surface has to be cleaned and free of any impurity. The samples have to be etched with a proper liquid to prevent damage. During the process, the sample is removed from the sample when the first blooms of grains are observed. After etching, the samples are washed ruinously with washing material, either water or alcohol. Warm air is then passed over it. If the material is of soft n ature, it must be covered so the surface can be saved (German, 1990). Microscopic examination This is a very important process since the examination with naked eye would not reveal the required results. Special method of illumination is used between the two controlling diaphragms to enlighten the eye piece where the results can be seen and photographed (German, 1990). Recording before the Procedure The two

To Kill a Mockingbird Essay Example for Free

To Kill a Mockingbird Essay The reason behind the title of Harper Lee’s To Kill a Mockingbird is that it is a sin to kill a mockingbird. Mockingbirds are considered innocent and selfless creatures. In Chelsey Philpot article The Long Life of a Mockingbird it stresses the importance of a mockingbird and the impact it has throughout To Kill a Mockingbird. Harper Lee’s definition of a mockingbird is seen continuously in the novel. It is that a person may be compared to a mockingbird if he is virtuous or without fault. Tom Robinson is an innocent man falsely accused of a crime and forced to defend his character. The false accusations that were forced upon Tom Robinson’s innocence reveal him as the greatest example of a Mockingbird in Harper Lees To Kill a Mockingbird. Firstly, a citizen of Maycomb County, Miss Maudie, thoroughly explains what a mockingbird is and what it means saying, â€Å"Mockingbirds dont do one thing but make music for us to enjoy†¦Thats why its a sin to kill a mockingbird†(Lee 119). To fully realize the mockingbird in Tom Robinson, the reader learns quickly that he is harmless. Adam Smykowski explains in Symbolism and Racism in To Kill a Mockingbird by saying, â€Å"A mockingbird symbolizes Tom Robinson, and underprivileged black people in general. They are innocent, and would never harm anyone. † Tom Robinson is a hardworking, African American. He lives with his wife and six children in a simple home in Maycomb County. An accident that occurred when Tom was young left him with absolutely no use of his left arm whatsoever. Laurie Champion explains in an article called Lees To Kill a Mockingbird that, â€Å"Toms left arm hung dead†. Even with the disability of his arm, Tom is a great example to his six children considering what terrible hardships had been placed on him throughout his life for no reason. The way that Tom conducts himself not only in private but also in public reveals his good character and genuine love for other people no matter what race or social class. Furthermore, Tom Robinson’s status as a mockingbird is seen through his kind and attentive actions toward others regardless of race. Tom’s actions toward Mayella Ewell reveal his status as a mockingbird. On his way to work, Tom frequently is asked by Mayella, a low class white woman, to come in and help her with chores and errands around the house. Just like a mockingbird expects no payment or reward for singing, Tom would not accept any payment at all for his kindness and help towards Mayella. She intern misinterprets Tom’s kindness and puts him in a difficult situation where she tries to seduce him. Tom immediately refuses. As a result she falsely accuses him of raping and assaulting her in order to hide her inappropriate sexual advances towards him. Moreover, Tom Robinson represents a mockingbird when he endures being verbally abused and harassed on the witness stand even though he is an innocent man. During his testimony, his handicapped arm is brought to the attention of the court while he is on trial. This proves that it would be impossible for him to have committed this crime due to the fact that her bruises from the assault where made by a man that, â€Å"led with his left hand† (Lee 177 ). Tom Robinson was proven innocent on many accounts. However, after a deliberation by the jury, he is convicted and will be killed in a futile attempt to escape from prison. In conclusion, Heck Tate summarizes Tom Robinson’s mockingbird symbolism when he compares Tom’s death to the â€Å"senseless slaughter of songbirds† (Lee, 323). Just like it is wrong to kill a mockingbird, it is wrong for the citizens of Maycomb to have killed Tom Robinson. The loss of his innocence is the reason he is the greatest example of a mockingbird in Haper Lee’s To Kill a Mockingbird.

B737 Ng Flight Control System Engineering Essay

B737 Ng Flight Control System Engineering Essay In this chapter the differences of the Airbus A320 and Boeing 737 NG will be discussed. There will be looked at the flight control system of the Boeing 737 NG and the flight control system of the Airbus A320 (2.2) after that a comparison between the conventional system and fly-by-wire system (2.3). 2.1 B737 NG flight control system This section will discuss the flight controls of the Boeing 737 NG. At first the primary flight controls especially the ailerons (2.1.1) and also the secondary flight controls of the Boeing 737 NG trailing edge devices (2.1.2) will be discussed. 2.1.1 Primary flight controls In this subsection, the primary flight controls of the Boeing 737NG will be discussed. The ailerons will be investigated as primary flight control in this chapter. The composition of the system (2.1.2a), the input of the system (2.1.2b), the transportation of signals (2.1.2c), the output signals (2.1.2d) and the hydraulic system of the Boeing 737NG will be discussed (2.1.2e) 2.1.1a Composition The aileron system exist of two ailerons. The Boeing 737 has an aileron on each wing. They are placed on the outer side of the wing to create a greater moment over the airplanes longitudinal axis. Over this axis the airplane will be able to roll. Because the ailerons are mounted on the outer side of the wing the needed forces can be lower than when they are placed on the inner side of the wing. The moment of the aileron is the force multiplied by the arm length. 2.1.1b Input The ailerons are positioned by the control wheels of the pilots. When the pilot controls his steering wheel a mechanical cardanic movement will make the input signal transferred to the transfer mechanism.The transferm mechanism keep the control wheel movement to a limit of 107.5 degrees left and right. This mechanism is mounted under the steering column of the pilot. The roll axis force transducer is mounted between the control shaft and aileron drum below the captains control column. The force transducer provides dual electrically isolated ac output signals that are proportional to the force applied to the control wheel or column. The signals are used by the autopilot computers when the system is engaged in CWS (manual) mode or in CMD mode with no flight mode selected. Both control wheels are cable mounted connected to each other, when the captain steer his control wheel the left aileron control bus drum will rotate and operated the control cable to rotate the right aileron control bus drum. This drum is connected exactly as the captains control wheel and the first officers control wheel will move. C:UsersTemminckDropboxHvA Projectgroep 1VProjectWerkmapKeespage 27-4.jpg 2.1.1c Transport By rotating the control bus drum, the control drum also will rotate. The control cable will be operated and will run through the airplane and routed by cable guides and kept on tension with cable tensioners. In the main wheel well the cable will be attached to the aileron body quadrant. On the quadrant the new outgoing cable is mounted. The quadrant is mounted on two aileron power control units (PCU). This PCUs are mounted at the aileron control quadrant. On this quadrant the aileron input shaft is mounted. On this shaft the autopilot control rod, the PCUs four pogo input cranks, the feel and centering unit and the aileron actuator are mounted. For backup two PCUs are mounted to help the pilot to create a higher force to the ailerons so the pilot dont need all his strength to control the ailerons. Also there are four pogo inputs installed between the body quadrant and the input shaft. These are to control the movement of the cables so that they are on tension at all times and not move when the dont need to. The feel and centering unit is used to position the ailerons to his neutral position. This can be done by movement of both aileron trim switches on the aft electronic panel. The aileron trim actuator can position the aileron input shaft to trim the system. The total trim the pilot have made can be read on the aileron trim indicator on the control wheel. The autopilot aileron actuator is duplicated for safety reasons. The autopilot actuator is with the autopilot input rod mounted to the aileron input shaft. This actuator will be electronic controlled by the flight control computers. All the actuators are hydraulic control led by system A and B. C:UsersTemminckDropboxHvA Projectgroep 1VProjectWerkmapKeespage 27-7.jpg 2.1.1d Output The control cables will led through the wings until they reach the aileron wing quadrant. This quadrant is kept on tension by the aileron cable tension spring. This for that the trenched out cables are kept on tension. The quadrant is connected with and pushrod connection to the aileron. On the aileron an aileron balance tab is mounted and connected with control rods. The aileron is armed with four balance panels to keep the balance in the ailerons. And this panels are equipped with fixed balance weights. The output signal of this system is that the aileron will move up or down after movement that the pilot will make by moving the control wheel. C:UsersTemminckDropboxHvA Projectgroep 1VProjectWerkmapKeespage 27-6.jpg 2.1.1e Hydraulic system The ailerons are powered by system A and B. When both of this systems fails, the aileron can still be operated manually by controlling the cables. The left aileron is powerd by system a and the right aileron is powered by system b. During normal operation of the ailerons, an aileron input goes through the input pogos of each PCU to its input crank. The upper and lower input cranks move, slides in the control valve, and supply hydraulic pressure to the actuator. The lower input crank is connected to the primary slide and the upper input crank is connected to the secondary slide. A torsion spring inside the PCU connects the two input cranks. Movement of the primary slide supplies one-half the total flow rate, and movement of the secondary slide supplies the other half. The primary slide moves to its full effective stroke before the secondary crank starts to move the secondary slide. When the primary and secondary slides move, hydraulic pressure goes through the control valve to one side of the actuator. This moves the actuator housing and the respective aileron body quadrant to the commanded position. The other side of the actuator is connected to the return. If one PCU cant supply a hydraulic pressure, its bypass valve will be activated and moves to the bypass position. This connects the two sides of the actuator, and prevents a hydraulic lock condition. When the pilot moves the control wheel, the ON side PCU still moves to his commanded position normally. As the ON side PCU moves, it also moves his respective aileron body quadrant and back drives the OFF side PCU actuator housing. When the OFF side housing moves, hydraulic fluid is pushed through the bypass valve. If one PCU input pogo cant move freely, the pilot must supply approximately 20 pounds of additional force to compress or extend the spring inside the pogo. The other PCU input pogo still moves its own input crank and slide to the commanded position. This equalizes pressure on both sides of the actuator and prevents a hydraulic lock condition. Now the other PCU can move the aileron body quadrant assembly normally. As the ON side PCU moves its respective aileron body quadrant it also back drives the OFF side PCU actuator housing. When the OFF side housing moves, hydraulic fluid is pushed through the bypass valve. During a manual reversion, the bypass valve receives no hydraulic pressure and moves to the bypass position. This connects the two sides of the actuator and prevents a hydraulic lock condition. When the pilot moves the control wheel more than three degrees, the primary and secondary input cranks hit the mechanical stops on the outside of the actuator housing. As the housing moves, hydraulic fluid in the actuator is through the bypass valve. Movement of the housing also moves the aileron body quadrant assembly to the commanded position.

Commanders of the Army of the Potomac :: Essays Papers

Commanders of the Army of the Potomac In his civil war book Commanders of the Army of the Potomac Warren Hassler Jr. fantastically recounts the events that transpired between 1861 to 1865 during which seven men were given the reigns of the North's Army of the Potomac and asked to lead the Union to victory. However, one of the greatest commanders in history stood in their way; Robert E. Lee, and each was pitted against this great general one by one and given the chance to make history. The first, Irvin McDowell was regarded in this book as a great soldier in his own right but a terrible leader who displayed visible gaps in his preparedness, in his tactics, and in his strategy. He was the first to take control of the northern army. Not much later towards the end of May of 1861 General Lee established a defensive hold along the small stream of Bull Run located in Manassas. During the Battle of Bull Run McDowell was crushed by Confederate generals Joseph E. Johnston and Pierre Beauregard due to weak planning and it be came apparent that this in fact would not be a short-lived war. Next up was the most popular and perhaps the greatest of the commanders, George B. McClellan. After the embarrassing defeats at Bull Run he masterfully regrouped and disciplined the AOP as he himself showed outstanding military presence and was constantly increasing his knowledge of offensive tactics. From spring of 1862 till July of that year General McClellan was successful in driving the Confederates out of West Virginia and he was inching toward the southern capitol of Richmond when General Jeb Stuart under Lee encircled and outmaneuvered McClellan's forces who were driven back and finally held at Malvern Hill during the Seven Days Battle. During this time period there was some shifting of control and the AOP was put into the arms of General John Pope. This book regards Pope as one of the most pathetic leaders of the Civil War as he screwed up and changed his ways during the second battle at Bull Run and sacri ficed his men uselessly. Meanwhile, McClellan blew an opportunity to catch the Confederates off balance after he learned of Lee's plans but stalled and hesitated for a day giving the southern reinforcements plenty of time to arrive and group together and the north escaped with a slight victory only after Lee decided it would be wise to withdraw his forces.

Writing For Design :: Personal Narrative Papers

Writing For Design I was born in Salem, Oregon, which is a fantastic place to leave. It’s one of those places that people appreciate more not having ever been there. They may have some vague idea that it’s the capital of the most underrated state in the country, but they are astonished that people actually come from it. Well, we do. Not a lot of writers, though. I think this is the case because to be a writer you can stay where you are, and that contradicts the basic drive of everyone born in Salem. However, before I left, I wrote things for me to say. You see, I shy away from the term â€Å"perform† because, in actuality, it was just me talking for the sake of talking. Which is why my first calling was acting. The first thing I ever wrote was a play about Zorro, with whom I was in the throes of a passionate love affair. It was legitimate, we had been secretly married, after all, but we could not be public about it because of his persona as a romantic super hero. It would have been devastating to his following, you understand. Like a Backstreet Boy. I talked the story out to my babysitter and she transcribed it for me. Every line was mine, every plot twist was mine, including the show stopper where Zorro discovers that the masked man stealing the pies off the window sill is in fact – shock – the obese sheriff. A little bit Scooby Doo, a little bit Bernstein Bears and Brother’s Problem With Kleptomania. I wish I could say that I had some cool Hawking-esque paralysis that prevented me from writing it myself, but the truth is I just couldn’t write. I was three and a half. Later, after my parents seemed utterly bored with Zorro and the Missing Pies after only three hundred performances, I began writing on my own. What, one might ask? Well, I am an only child†¦ I invented siblings. There were four of them: two older, two younger, two boys, two girls. With me in the middle. I like balance and symmetry. We were like the Box Car Child ren or those orphans in Homecoming, but with really cool, undead parents. In addition to my chronicle-writing duties, I had to take care of these characters I had created. I made them soup when they were sick.

Biblical Archaeology: Dating Techniques

As our civilization grows, there is also a growing passion for knowledge of the past. Archaeology is fast becoming one of the popular sciences. Most archeological finds are composed of shreds of pottery or ceramics. As archeology and modern science progress many dating techniques are being developed to be used on these fragile artefacts in order to give us a brief glimpse of our past. Many techniques are now available which allow the detailed physical and chemical characterization of ceramic artefacts.Given a suitable archaeological sample it is now possible to determine many aspects of technology, provenance, and, in some cases, its use. Several dating techniques used in archeology are superposition, artifacts of known age, stratigraphy, dendrochronology and thermoluminescence. This paper shall focus on Ceramic Analysis using three of these techniques: Dendrochronology, Radiocarbon dating and Thermoluminescence. Carbon 14 Radiocarbon dating or Carbon-14 dating is the determination o f the approximate age of an ancient object, such as an archaeological specimen, by measuring the amount of carbon 14 it contains.Radiocarbon dating was discovered by a team of scientists led by Prof. Willard Libby of the University of Chicago after World War II. Since plants and animals take up carbon-14 during their lifetime. The amount of carbon-14 in them exists in equilibrium with the C14 concentration of the atmosphere and the ratio of C-14 to C-12 remains about the same as the ratio in the atmosphere. As soon as a plant or animal dies, they cease the metabolic function of carbon uptake; there is no replenishment of radioactive carbon, only decay.This rate of decay was calculated by Libby’s team to be 5568 years per half-life, this means that half the C14 in the original sample will have decayed after 5568 years and after another 5568 years, half of that remaining material will have decayed, and so on. This rate of decay is what is now know as Libby’s half-life wh ich he measured at 5568 ±30 years. The true advantage of the radiocarbon method is its capability to be uniformly applied throughout the world , this is probably the primary reason why it is one of the most widely used and best-known absolute dating methods.However, it is not without its flaws, radiocarbon dating has the following limitations: 1. that after 10 half-lives there is a very small amount of radioactive carbon present in a sample, at about 50,000-60,000 years radiocarbon dating becomes inaccurate. 2. the ratio of C-14 to C-12 in the atmosphere is not constant. This variation is due to changes in the intensity of the cosmic radiation bombardment of the Earth, the 1950’s nuclear testing and the depletion of the Ozone layer.3. in rare cases, a â€Å"reservoir effect† will give C-14 dates that are much older than the true age of the sample because â€Å"some plants and animals live in very unusual environments whose C-14 content is much lower than normal. â⠂¬  4. Contamination of the sample also limits the accuracy of Radiocarbon dating as when porous samples contain recently living material with a full â€Å"charge† of C-14. Finally, Radiocarbon dating can only be used on living organisms. DendrochronologyDendrochronology is the science that uses tree rings dated to their exact year of formation to analyze temporal and spatial patterns of processes in the physical and cultural sciences. Its main function in archaeology is to use tree rings to date when timber was felled, transported, processed, or used for construction or wooden artefacts such as a beam or pole of an ancient structure. The principle behind using tree-rings is that â€Å"tree-ring sequences from trees that grow in a seasonal climate, i. e., with one growth increment per year, with the size of that growth dependent upon some climatic stimulus such as cold in the Polar regions, drought in the Aegean, and various combinations of the two stimuli in regions in bet ween, can be compared so that these increments, more popularly known as â€Å"rings,† can be dated to the calendar year in which they were formed. † Aside from the principle of using tree-rings, the use of Dendrochronology is governed by several other principles, these set of scientific rules must be adhered to in order for the result to be flawless.There is the Uniformitarian Principle which states that â€Å"physical and biological processes that link current environmental processes with current patterns of tree growth must have been in operation in the past,† the Principle of Limiting Factors which states that â€Å"rates of plant processes are constrained by the primary environmental variable that is most limiting,† The Principle of Aggregate Tree Growth which states that â€Å"any individual tree-growth series can be â€Å"decomposed† into an aggregate of environmental factors, both human and natural, that affected the patterns of tree growth over time,† The Principle of Ecological Amplitude stating that a specie of trees â€Å"may grow and reproduce over a certain range of habitats, referred to as its ecological amplitude,† the Principle of Sites Selection which states that â€Å"hat sites useful to dendrochronology can be identified and selected based on criteria that will produce tree-ring series sensitive to the environmental variable being examined,† the Principle of Cross-dating which states that â€Å"matching patterns in ring widths or other ring characteristics (such as ring density patterns) among several tree-ring series allow the identification of the exact year in which each tree ring was formed. † and the Principle of Replication which states â€Å"that the environmental signal being investigated can be maximized, and the amount of â€Å"noise† minimized, by sampling more than one stem radius per tree, and more than one tree per site,† the application of which is not limited to Dendrochronology only.The methodology used in Dendrochronology is cross-dating, or matching patterns of ring-growth from one tree to another and assigning rings to specific years, however, this possible only among trees growing in the same general climatic region. The good thing about dendrochronology on the other hand, is that cross-dating can sometimes be achieved in spite of human interference to ring-growth such as thinning of stands, resin-gathering, fire damage, and other traumas such as severe weather effects, pollution or lightning damage, not to mention shaping of the wood at the time of construction and decay afterward. Furthermore, visual and statistical techniques are employed to guarantee the accuracy of the matches and in addition to simple ring-width analysis, X-ray densitometric methods are used to reconstruct past environmental conditions.It is also possible that wood or charcoal samples taken from standing buildings or excavated from archaeological site s be crossdated with each other and with wood from living trees to extend the tree-ring chronology beyond the date of the oldest ring of the oldest living tree in the region. Scientists believe that the best advantage of dendrochronology is that it is the only archaeometric technique where determination of absolute dates accurate to the year is either theoretically or practically possible, but, just like any other method of dating artefacts, it suffers from several limitations. The following limits the use or accuracy of Dendrochronology: 1. in some areas of the world, particularly in the tropics, the species available do not have sufficiently distinct seasonal patterns that can be used 2.in cases where the right species are available, the wood must be well enough preserved that the rings are readable to the point that there must be at least 30 intact rings on any one sample. 3. in order to produce an accurate result, it is necessary to have samples of timber that retained their bar k, so that it is clear which ring was the outermost when it was felled. 4. it can only be used if there is an existing master strip for that area and species; if the only master chronology available for the region is oak, cross-matching with timbers of these other species cannot be relied on. 5. use of this technique is also limited on how far back in the past things can be dated with tree rings although bristle cone pine trees can live to 9,000 years, this is a very rare phenomenon. 6.â€Å"sapwood is highly susceptible to decay particularly by beetle larvae and as a â€Å"result all sapwood may have been removed from the accessible surfaces of timbers during building repairs and conservation work, making it impossible to determine when the timber was felled. † 7. it may give inaccurate results on the actual date of the structure if it so happens that the date the timber was felled is not necessarily the date that the building was constructed or that the timber used was imp orted from another area. 8. in some places, prehistoric people may have built their structures using timber however, in most of the world that did not begin to happen until about 4,000 to 5,000 years ago.Thermoluminiscence Thermoluminescence dating is the determination by means of measuring the accumulated radiation dose of the time elapsed since the material containing crystalline minerals was either heated or exposed to sunlight. The application ranges from â€Å"Lower Paleolithic to Neolithic archaeological sites, with a major focus on the Middle Paleolithic, which is often beyond the range of the radiocarbon method. † The principle behind this unique dating technique is based on the â€Å"storage of information about the absorbed radiation in inorganic crystals. † It is based on structural damage and faults to the crystal lattice of minerals by ionizing radiation.The sources for this omnipresent radiation are radioactive nuclides from the surrounding sediment and f rom the sample itself, as well as secondary cosmic rays. Thus a radiation dose accumulates in the crystal in the form of electrons in excited states, of which some are metastable and thus resident over periods of time long enough to allow a dating application. During the first heating of the artefact, if the temperature is high enough (400 ° C), the drainage is sufficient to relax all electrons relevant to the luminescence method used; that is, the clock is set to zero and through the years it starts to accumulate natural radiation, upon its second heating it releases all this stored radiation in terms of thermoluminescent light.The released light is then correlated to the absorbed radiation which is then correlated to the archeological age. In practice, knowledge of the composition of the artefact is of importance since the nature or chemical composition of it, as explained above, determines the amount of natural radioisotopes present in it. These natural radioisotopes are respon sible for the greater part of the radiation that is absorbed. If the composition of the artefact is known, then the archeological age of the artefact can be computed by using the â€Å"total amount of absorbed radiation divided by the absorbed dose through internal and external radiation per year. †The greatest advantage of Thermoluminescence dating over other methods is not only the direct association of the event with past human activity on a linear time scale, but also its smaller vulnerability to unknown variation of certain parameters. However, Thermoluminescence dating is still prone to errors and inaccuracies. The evaluation and publishing of results must be done with due care and must meet with certain standards which includes the presentation of glow curves, heating- and DE-plateaus, growth curve(s) and the determination of the alpha sensitivity of each sample. Also, equal care has to be taken in the evaluation of parameters prone to variation with time. ConclusionEa ch of the three dating techniques discussed has its own peculiar way of finding the archaeological era that a sample was created or may have died: Radiocarbon depends on decay, Dendrochronology depends upon growth and thermoluminescence depends upon absorption. The three techniques however different they may be are still connected by a linear timeline, when the accuracy of one technique ends, another begins. Dendrochronology can only be used as long as there are master strips which may reach only up to a maximum of 9,000 years old, results obtained through Radiocarbon, on the other hand, can only be accurate up to 50,000-60,000 years old while Thermoluminescence dating ranges from 10,000 to 230,000 years old. The three dating techniques discussed have their own advantages and disadvantages.In the end, the scientist is the one who weighs all the pro’s and the con’s of any technique and he is given the discretion on what technique to use which he thinks is more appropria te and shall give out more accurate findings. BIBLIOGRAPHY Berger, Thomas. Thermoluminescence Dating: A Brief Overview. http://www. ati. ac. at/~vanaweb/papers/archview. pdf Fagan, Brian M. and George H. Michaels. Dating Techniques in Archaeology. http://www. mc. maricopa. edu/dept/d10/asb/anthro2003/archy/dating/datingtech. html#Dendrochronology Freestone, Ian. Ceramic Analysis. http://ads. ahds. ac. uk/catalogue/adsdata/cbaoccpap/pdf/117/11710001. pdf Grissino-Mayer, Henri D. Principles of Dendrochronology. http://web. utk. edu/~grissino/principles. htm Higham, Thomas. The Method. http://www. c14dating. com/int. html Hirst, Kris K.Radiocarbon Dating Method. http://archaeology. about. com/od/rterms/g/radiocarbon. htm Kuniholm, Peter Ian. Dendrochronology. http://www. arts. cornell. edu/dendro/ajatext. html Richter, Daniel. Advantages and Limitations of Thermoluminescence of Heated Flint from Paleolithic Sites. http://www. eva. mpg. de/evolution/staff/richter/pdf/07-RichterGeoarchae ology. pdf Robinson, B. A. How does Carbon-14 Dating (C-14) Work? Is it Accurate and Reliable?. http://www. religioustolerance. org/c14dats. htm Taylor, Jonathan. Dendrochronology in Dating Timber Framed Building and Structures. http://www. buildingconservation. com/articles/dendrochron/dendro. htm