Theories of Learning for Classrooms

Theories of study for material bodyroomsLearning is the process that results in a relatively enduring change in a person or persons (Alexander et al, 2009 186). Learning is a dynamic process whereby the students companionship and skills be distinct before to after development (Winn, 1990). T altogether(prenominal)ing is by definition the promotion of breeding and ought therefore to be informed by the best of our knowledge about development. Learning and teaching method poses a synergistic relationship that is teachers take up to teach with an set about that reinforces how students course learn (Muijs brooks book).A number of educational researchers offer breeding paradigms to explain how mortals learn. The way students learn buns be mapping to foster impressive teaching serves, and ultimately align teaching with positive study and educational experiences. Understanding how knowledge is developed and comprehended tooshie allow teachers to shape the methodological delivery of their subject content to match the theoretical frameworks, underpinning how knowledge is processed. Attending to the nature of student information nooky allow teachers to improve their practice and in turn the quality of the students experience (Macleod Golby, 2003). The extremes of this encyclopedism possibility spectrum are represented by the Behaviourist and Constructivist theories of education.Behaviouristic Theory of LearningLearning, according to behaviourists (Watson, Pavlov), is defined as acquisition of new behaviour. The focalize of behaviourism is on the conditioning of observable human behaviour and is base on the principal impressionion that a reaction is made in response to a specific stimulus. This reaction breaths to a consequence. If the consequence is pleasant and positive, the behaviour change be infers reinforced. With consistent keep, the behaviour convention becomes learn and is automatically activated upon stimuli presentation.Physio logically, behaviourist theories propose that teaching is achieved through livelihood of a bad-tempered neural pathway, which links the stimuli and response in the brain. This activation and reinforcement results in a high-velocity, smoother implementation of certain reactions and responses. The connections between the stimuli and specific responses are built correctly and then reinforced over time through practise and repetition, which ultimately strengthens the neural pathways, resulting in a more efficient response to the stimuli. (Pritchard).Behaviourists verge this form of learning conditioning, whereby with consistent reinforcement the behaviour pattern becomes conditioned. Classical conditioning involves the reinforcement of a natural reflex or behaviours which occur naturally as a response to a specific stimulus. In contrast, operant conditioning involves reinforcing a behaviour by praising it, or discouraging undesirable behaviour with punishment. The rewarding phase s of this conditioning processing is known as reinforcement. However, this stimulus-response relationship discounts any noetic processes which may be involved in learning.Researchers, including Vygotsky 1962 amongst others, began to criticise the behaviourist undertake, as it was seen too teacher centred and directed, void of meaningful learning and the teacher process was foc officed too much on individual rather than collaborative group work. In addition, the cook upivist attitude challenged the implied separation between noetic processing and knowledge, which had to be bridged by the role of a teacher.Constructivist TheoryThe constructivist movement was formed on Piagets (1976) and Vygotsky (1986) work who view learning as the effect of psychical construction, whereby pupils combine their existing knowledge with new information, to construct meaning and formulate their fellow feeling. The constructivist conjecture proposes that learning is an active process, a social ac tivity, contextual, centred on constructing meaning and regards the learner as a responsible agent in their knowledge acquisition (Loyens 2007. In constructivist learning, individuals draw in their experience of the world around them and work to rent sense of what they perceive in order to build an disposition of what is surrounding them (Harris, 1994). Since constructivism involves learners to interact with their immediate learning environment, learning has been considered to be situation-specific and context-bound activity (McInerney and McInerney, 2002.Constructivism is an umbrella term to encompass the wide range of constructivist perspectives, which can be separated into two branches cognitive constructivism (Piaget, 1976) and social constructivism (Vygotsky, 1986). Both sub-types believe that knowledge is actively constructed by individuals Birenbaum 2003, yet through the use of different mediums either through a series of internal, intellectual arcdegrees (cognitive constr uctivism), or by social interaction including interactions with world based, external experiences (social constructivism). The legion(predicate) perspectives on constructivism within these two sub-types could be essentially grouped around a rooted premise about learning. That is, knowledge is actively constructed by the learner (Birenbaum 2003 Harris and Alexander 1998)Piagets developmental stages theory, which represents cognitive constructivism, presents four age-referenced development stages which provide a theory of gradual cognitive development up to the age of eleven days old. The stages refer to an explicit age range and characterise the cognitive abilities necessary at each stage to construct meaning of ones environment.Social constructivism emphasises the role of linguistic process in the process of intellectual development. Vygotsky considered dialogue, usually exclusively not always with a more knowledgeable other, as a vehicle by which concepts are considered, share d and developed. The dialogue, which is based on learners pre existing and catamenia knowledge (schemas), is then exploited to develop and construct new ideas and understanding. Vygotsky advocates that the process of learning involves moving into and across a zone of proximal development, which is aided by the intervention of another through support. The zone of proximal development is a theoretical space of understanding which is just above the direct of an individuals latest understanding. The process of giving support to learners at the appropriate time and level of sophistication to meet the individual require is termed scaffolding. Scaffolding can allow the movement from one zone to another and assists in the passing through the zone of proximal development.From reviewing the literature, educational researchers which employ these constructivist principles accept aspects from two strands of this learning theory (Biggs, 1979, Cunningham, 1996), and use constructivist theor ies as a generalised term. However, as Mathews and Lui highlight, combining the plethora of constructivist variants is questionable, and generalisations made may have less logical implication and loss of meaning. thusly, for the purpose of this assignment, the term constructivism will reflect a collaboration of both social and cognitive strands however specific branches and the implications of these strands are highlighted where necessary.Critique of learning theories and associated implications upon schoolroom practiceA review of the literature suggests that behaviorist learning does not offer students the chance to develop deep meaning and understanding (Einworth and Collins), besides instead has a tendency to promote superficial learning of skills (Fosnot, 1996). Making a correct response and remembering content does not necessarily call for understanding, and consequently the actual understanding achieved through behavioural approaches is challenged. Hounsell, Entwistle, 1 997 conclude that the use of rote memorisation represents a learning approach to a surface level of understanding, whilst establishing connections with current knowledge reflects an approach for a deeper level of understanding.In contrast, from a constructivist perspective, the principle of learning utilise prior experience is beneficial in promoting a deeper and richer understanding (Pressley, Harris Marks, 1992). Demerici advises that information which is connected to a learners prior experiences is more likely to be retained, explaining higher retention rates when a constructivist approach is adopted. (Demirici). According to Fosnot, the focus of attention in constructivist perspective is concept development and deeper understanding. This research suggests that constructivist approaches lead to a great, richer and deeper understanding. It is therefore plausible to suggest that the quality and depth of understanding associated to a constructivist teaching approach is more likely to exceed that of the behaviourist approach.However, as Entwhistle and Smith (2002) invest, the association between memorisation and surface approach may be weak. Kember, 1996 Watkins Biggs, 1996 reported that memorisation can be used to learn unfamiliar terminology, as the first stage to establishing understanding. This concept, where memorisation is part of meaningful learning, is defined as memorising with understanding (Marton, Watkins,Tang, 1997 Meyer, 2000, and has been conducted by students as a successful revision tool (Entwistle Entwistle, 2001) In addition, (Smith, 2001, 2002a) affirms that rote learning can contribute to understanding.Therefore, it appears that behaviouristic learning approaches can be beneficial for certain tasks such as establishing classroom behaviour (Fulton). Teachers could consider deploying beahviorusitlic approaches to the learning of classroom behaviour, curiously for pupils who display anxious tendencies and low take up (Prittard Fulton). Those of higher academic ability perceive simplistic drill and practice unsatisfying and dull (Prittard). In addition, some students demand understanding, yet adhering to behaviouristic learning approaches does not accommodate this craving. In other situations, the concepts of learning without understanding can fuel frustration, lead to misconceptions and generate a difficult learning environment (Prittard).Controversially, dun (2001) suggests that the constructivist theory may imply that remembering is not important, and that learning is solely centred on understanding concepts. However, neither of these are true, and creation able to remember knowledge is an important pre necessary of learning. In addition, Biggs, (1998) and Jin and Ortazzi, (1998) have reported that constructivist teaching approaches dont consistently guarantee teaching effectiveness. Instead, traditional, more behaviourist approaches to learning in large classes has prove to be successful internationally, su ch as in China.Fox, 2001, argues that constructivism neglects the role of memorisation and mechanical learning techniques Arguably, due to the varying nature of meaning which is uncontrollably constructed by students, in some cases, rote learning and memorisation may be more useful when teaching factual concepts and where clarity in understanding is required. rote learning learning may be used to armed service students cope better with some aspects of work that they find difficult. However, teachers must consider that rote learning is not an approach to develop understanding and therefore where possible, should be followed by attempts to encourage understanding.Standard school and classroom routines and expectations for behaviour can be learnt through behaviouristic approaches. In the case of behaviour management, a strategy to quieten the class, such as raising of the hand, or counting down from three could be in effect used. In this case, the stimulus, such as the teacher raisi ng their hand or calling out the number three, must be fully explained to the class. In addition, the stimuli must be fully visible and audible to the students, which is possible with a clearly risen hand or an assertive voice. The response desired, such as a student raising of the hand and silence, must be fully understood by students.It is important that the stimulus-response occurrence should be repeated by the teacher and used regularly. The same strategy should be employed every time the teacher wants to quieten the class, establishing uniformity of stimuli and behavioural response. This repeated activation strengthens the pathways, affording for a smoother and faster implementation of the response. . Pupils should be made alert of the negative and positive consequences if they do not respond to the stimuli as desired and the consequences need to be kept consistent. Therefore, consistency of behaviour management strategies is crucial and classroom practice must adhere to the same strategise as the same stimuli is presented for a specific response.Behaviourism relies on reinforcement which is employed to condition the behaviour, and therefore is essentially the tool which brings about learning. Therefore rewards and punishments for behaviours must play a crucial role and actively administered within classroom practice. Behaviourism may therefore stimulate and encourage more use of positive reinforcement which has been a long standing effective classroom practice (Elliott and Busse, 1991 fulton book). However teachers must consider that rewarding children who are already highly motivated may not be as effective, and may actually lead to a loss of interest (Fulton) Rewards and praise have been shown to enhance motivation, and serve as an effective behaviour management tool, however, praising students may not come naturally to teachers.However, behaviourist approaches dont take account of mental cognitive processing involved in learning. In contrast, const ructivism emphasises that the learners must develop their understanding for themselves and constructivist researchers advocate that mental activity is the lifeblood of learning and the extent of what is learnt (Howe 1999). Teachers cannot assume that the products of learning are solely the teachers effort and thought instead learning requires effort on the part of the learner. Teachers need to offer scope of activities where the accustomed effort and activity falls on the learners responsibility. Such opportunities would afford learner net and optimise the possibility of effective indestructible learning taking place (Prittard).A vast array of supportive literature endorses the success of positive approaches. Research informs that learning through such constructive mediums, like discussion, participation, practice, are successful and associated with learning pull ins and knowledge retention. Demirci Yavuz (2009). Dericimi also reported a significant difference in post-test grad es and retention learning tests grades, with the constructivist approach being more efficient than the conventional, behaviouristic approach.However, the constructivist theory may imply that all individual differences in learning come down to the consequences of each learners history of learning )Loyens, 2008.Furthermore, although we do learn by acquiring knowledge from our environments through interacting with the external world, Fox highlights that the environment also acts upon learners. That is, we act and react and learning can be achieved from both experiences. However, constructivism appears to fail to acknowledge adaptive instinctive responses as reactive forms of learning (Fox, 2001) and the role of talent in cognitive development. Furthermore, Fox (2001) and Bredo, (2000) argues that constructivism discounts the role of innate, motivational and genetic factors in knowledge construction, which have been proven to play a role in cognitive development and ealrning Carey Spel ke, 1994).Another assumption refers to an epistemological assumption that students actively seek resources and experiences, which are anchored by their pre-existing knowledge. In addition, it is assumed that learners utilise the construed data to actively construct their knowledge (Renkl). Therefore, this approach to learning relies on students encountering experiences and applying these experiences to their pre-existing knowledge to develop their understanding. However, such experiences and world-based interactions may not be feasible or available to students due to their lifestyle circumstances. Consequently, teachers need to be aware that understanding and meaning is limited to the individual experiences of the students. In accordance with this assumption, the constructivist theory can explain why pupils conceptions and meaning do vary between each other (Taber, 2000). Given that learning is achieved through the constructing activity of the student, the individual can only unders tand or know what he or she has constructed (Dunn and Cunningham, 1996).Therefore, constructivism may be seen as subjective and relative (Duffy and Cunningham, 1996).. This may lead to marking criteria discrepancies, confusion and inconsistency, and student misconceptions, which do not match reality. In addition, Duffy and Cunningham propose that if the constructions and meanings are different amongst students, the little shared understanding may challenge the ease of communication between learners and the class. This may jeopardise the effectiveness of class discussions and social interactions as a tool to enhance learning.Similarly, as construction is activity on part of the learner (Bruner 1966, 1971), what is constructed cannot be controlled by the teacher. Instead the learner has autonomy and self-regulates what understanding is established. Therefore the students constructed understanding may not parallel with other students, with reality or with the teachers construction and understanding. Consequently, teachers must not assume that the construction and understanding of a concept is universal between all students. Instead teachers must actively access and consider the alternative perceptions and understanding of the learners hence why a transmission approach is fruitless.On the other hand, teachers come into the classroom with their own construction and conceptions of subject content, and according to Patrick 1988, are not neutral. Therefore, a teachers understanding can colour the students understanding, and together, Patrick, 1998 and Marton and carrell (1997) suggested that some teachers moulded the students construction of a concept to align with their concept reading material. Ellisowths review concludes that the form of understanding impressed onto students is largely dependent on the teachers personal interpretation of the subject content. Therefore, although the constructivist theory assumes that the construction of understanding is the produc t of the learners interpretation exclusively, the constructivist theory does not account for the interplay between teachers and learners comprehension.Importantly, to garter progressive learning and avoid ontogeny misconceptions, teachers need to provide a clear focus and goals, with explicit learning objectives, which are rooted within pupils existing knowledge. The clear objectives allow students to construct their ideas using current knowledge and understand the overarching direction and progression oftheir learning. Activating prior knowledge is important to elicit pre-knowledge, allowing teachers to decipher the conceptual frameworks they are operating within.Teachers need to highlight the links between students existing knowledge and the new subject knowledge, to help the learner form bridges and facilitate their mental construction and cognitive processes (REF). By forming these links, students can activate and recall their pre-existing knowledge, and use this foundation to build and integrate new concepts. Teachers should encourage students to relate new knowledge to current knowledge and external experiences, allowing the new subject content to become embedded within the existing knowledge structures, contributing to or amending to the students schema.Since learning constructively is based on the addition of new content to current knowledge, the learner must have sufficient levels of understanding before new content can be used to construct more complex meaning and progress. Teachers and educators need to consider that new content cannot be built up until the foundations, such as current knowledge, is secured.To accommodate these pre-requisites of learning, the individuals knowledge needs to be continually assessed. As a regular classroom practice, formative assessment could be used as a regular approach to assess existing and new understanding, before moving to the next lesson. Formative assessment is a regular, informal mode of assessment, allowin g teachers to monitor students progress, gain an appreciation of what has been learnt and adapt their teaching practices to optimise further learning (Black and Wiliam, 1998). Accordingly, given that learning is an active and evolving processes, formative assessment can be used by teachers to assess, monitor, challenge unclear perspectives and adapt classroom practices to accommodate the constructivist principles of learning. Therefore, it is reasonable to believe that constructivist approaches to learning favour the use of formative assessment and may prompt its use in the classrooms, which Lamon, 2001 reports as being more valuable.Since formative assessment alone is associated with learning gains, (Black and Wiliam 1998), learning is positively influenced indirectly via adopting teaching strategies which are aligned to learning constructively. Formative assessment may be undertaken through inquiring, teacher and pupil discussion, peer assessment and interaction with peers. Forma tive assessment will also identify pupils individual learning needs, supporting teachers conduct in differentiation to assure pupils are moving forward, across their ZPD and optimise learning gains. Formative assessment can be achieved in the classroom, through discussion, questioning, peer assessment, self-assessment and feedback.However, with behaviourism, the opportunities for feedback are confined to only whether the response desired is correct or not. There is little scope for learning, or how to improve in order to meet the desired response. Therefore, under behaviourist approaches, feedback cannot be used for learning purposes, therefore opportunities for assessment for learning, which have shown to enhance learning, may not be fruitful. Consequently, limited feedback combined with the objective outcomes of behaviourist approaches mean that individual student needs are not necessarily part of the formulae when considering teaching strategies and subject content. The need to c onsider individual needs is undeniable, therefore such constraints of feedback extent presents a multitude of problems to the teaching and learning of students.When constructing new concepts and developing understanding, reviewing and reflecting on what has already been learnt also helps to establish and secure students previous knowledge. In addition, by asking what students understand before embarking on a new concept would help students form links between new and previous knowledge (Fulton). This reviewing could be done as a starter, but also plays a role at the end of the lesson, forming a plenary. Teachers should consider, incorporate and plan for well managed plenary to consolidate knowledge. Time to reflect upon what has been undertaken, the processes and the content gives the opportunity for internalisation and for a deeper level of understanding to be developed.Similarly, learning is most effective when learners become engaged, which means that teachers need to adopt an act ive approach to learning and involve engaging tasks to promote learning in the classroom. Learning using authentic tasks, which allow pupils to relate to their own experience inside and outside the classroom (Selinger, 2001) increases the probability of engagement with the task and supports findings that learning in a familiar context is most effective. Authentic tasks are likely to hold the attention and interest of children, and lead to a deeper level of engagement than with non-authentic or less authentic tasks (Fulton). Favourably, the constructivist principles match those fundamentals associated with effective learning.This active perspective of constructive learning (Phillips, 1995) is often contrasted with behaviourist stimulus-response relationship, which has been defined as a passive view in learning. However, reading and listening are included within this constructive approach to teaching, which could be argued to be more passive approaches. Whilst this suggests that all c ognition is active, to talking and writing, listening and reading are relatively passive. Traditionalists do not deny the importance of dialogue, and this may be utilised in questioning and answering, it is more that behaviourists place greater emphasis on knowledge and on the teacher as being knowledgeable, rather than learners and their existing knowledge (Fox). A counterweight is needed between emphasis on the teachers and learners, since too much emphasis on either part can lead to prescriptions for teaching which may do by the students needs or dismiss the teachers as a significant resource of knowledge.An active learning approach can be achieved by encouraging students to look concepts and ideas, and to follow their instincts (Wray and Lewis, 1997). Given that exploration can promote sequential development of ideas, it is likely to assist in the construction of new knowledge the roots to constructivism. Classroom practice could be based on a discovery-based approach Huitt, 2004, where students can find answers out for themselves, answer their own questions through experimenting with new ideas and discuss their beliefs and opinion patterns with their peers. Importantly, engaging with each other reflects social interactions, which can be a vehicle to develop understanding using social interaction.Unlike behaviourist approaches where the teacher is the primary resources of knowledge and is influenced by their interests and perspective knowledge construction offers the opportunity of learning to become dynamic and varied, opposed to being static and prescribed (Sudizna). The use of resources promotes more interactive learning and interest, which are both shown to positively influence learning.Behaviourist approaches have been criticised for not addressing this dynamic nature of learning as its theory assumes a static and standardised view of knowledge learning. Supported by Winn 1990, student knowledge is dynamic and changes, that is knowledge and skills are different before learning to after instruction, and behaviourism does not take this into account. In addition, behaviourism theory does not appreciate that students come into classrooms with prior knowledge. Conversely, the constructivist theory acknowledges that pre-existing knowledge is requisite of learning and that students enter classrooms with pre-conceptions, knowledge and beliefs which they deploy in constructing new understanding. (Jones, Carter, Rua, 1999)As already discussed, scaffolding is crucial for the learner to pass through their zone of proximal development, and can be undertaken by the teacher. Scaffolding can be practiced in the classroom in many ways, and teachers need to appreciate that this is fundamental to the educational progression of students and how this may be achieved. Support materials need to be widely available, such as a writing frame to support a particular style of prose, or a list of words to help in the process of completing an exercise, designed to assist understanding The provision of practical apparatus, especially in science, may help to explain the solution to a problem and is an engaging approach. Students can evidence reality and attach a sense of perspective and reality to their learning.Given the exploratory nature of constructivism, classroom practice needs to be supportive and generate an environment where the student feels safe to ask for help and comfortable in approaching the teacher. The teacher must be aware of the different supportive needs of the class, and meet these through differentiation and allowing time for class discussion, misconceptions and any lack of understanding. To help the teacher identify those who need more support than others, formative assessment can be incorporated to highlight the students individual needs that need to be addressed. Ultimately, this will allow tasks to be designed and geared towards the individuals learning ability.Unlike, behaviourism theories, constructivist theory accounts for the role of social learning and likely of interaction and recognises the importance of social interaction (Phillips, 1995). Incorporating social interaction opportunities, using language as a medium to construct ideas in groups of varying sizes, both with and without the teacher are encouraged and popular in classroom practice today (Jones and Brader-anjerie, 2002).Dialouge is proposed to constitue a crucial component of the constructivism paradigm ((Greeno et al. 1996 (Steffe and Gale 1995).Loyens, 2008. Discussion is fundamental and can be used through augmenting, debating, discussing concepts, teacher questioning and pupils presenting. Teachers should encourage students to work collaboratively, in pairs or small groups, and allow them to help each other and construct their own meaning in their own words of a concept. Dialogue with others allows additional and alternative perspectives to be taken into account when developing personal conclusions. varied knowl edge, points of view and understanding can be given and considered before moving on. Teachers should listen to pupils, and use their words for explaining concepts and draw on other opinions of class members.Constructivist theory also takes into account that learning is contextual. Evidence suggests that learning occurs in real-life contexts and learning is actually linked to a context, as deduced by Macleod and Goldby 2003. Children working with new ideas in a familiar content are more likely to engage with the ideas, than if the same ideas were present in an alien context. Therefore teachers should strive to include more authentic tasks and set learning concepts which are aligned with students familiar contexts. If a learning activity falls beyond the cultural understanding of the learning, then learning is likely to be less successful than if it had been situated in a more familiar setting. .Meaningful contexts for learning are very important however, what is meaningful for a teac her is not necessarily meaningful for the student. The association between the concept of learning being situated and the need for authentic learning tasks is evidence (McFarlane, 1997).However, the recommended approach to situation learning in meaningful contexts (e.g. Lave Wenger, 1991) has been argued against. Walkerdine, 1988, for example argued that if school learning became situated solely within the lived world of daily experiences, the opportunities for abstract reason out and reflective activity, which are all constituents of constructivism, would become limited and sacrificed, whilst confining students to their local xxxxxxx?The exactness of the Piaget stage of development has been criticised, that is to say children may pass through the stage, but it is not clear that they will pass through the stages at specific ages, however, as a developmental trail, this theory is useful in teaching practices. Piagets stage developmental theory offers guidance covering the level of complexity that may be expected in a childs thought processes at approximate stages in their development. Whilst Piagets developmental stage theory influences principally primary school teaching practices, given the ages this theory is related to, the appreciation and awareness that c

Composites Used In Aircraft Structure Engineering Essay

Composites Used In Aircraft Structure Engineering EssayThis report explores the uses of composites in modern aircrafts and investigates the technical effect of applying composites to aircrafts. In addition, this report also evaluates the early usage of composites in aerospace industry.BackgroundComposites ar defined as engineered materials made from two or more piece materials with significantly different physical or chemical properties those remain separate and distinct on a macroscopic level within the finished structure. (Definition, 2010)The American Heritage Dictionary (Houghton Mifflin, Boston, 1981) comes close, with a complex material, such as wood or quality glass, in which two or more complementary substances, peculiarly surfaces, ceramics, glasses, and polymers, combine to produce some structural or functional properties not present in any individual component. The problem with even a good enough definition, of course, is that it is all encompassing, so that every material in the universe could in some sense be defined as a composite. (Composites Manufacturing, 2006)Composites are branch introduced later on crash cases of aircrafts collectible to metal grind in the 1950s. And since thus the use of composites in aircrafts increases exponentially over time.Method of InvestigationIn changeation is obtained online in the form of e-books, news articles and industrial reports. Furthermore, relevant book from SP library had been utilise in this report.Scope of InvestigationThis report explores the history of composites. Besides, this report also explores the types of composites utilise in aircraft structure, for example deoxycytidine monophosphate graphic symbol, fiberglass and Kevlar aramid, as tumesce as fabrication of the carbon fiber. Furthermore, this report discusses the technical effects and applications of composites in aircraft structure. Composites in the future such as self-repairing composites and shape memory composites are al so discussed in this report.History of CompositesComposites were introduced in the 1950s and 1960s, fiber-reinforced plastic, was introduced to substitute the usage of duralumin in the structure of aircrafts. earlier composites were introduced, primary structure of aircrafts was made largely of aluminum alloy.Duralumin, a type of aluminum alloy, was wide used in aircrafts primary structure due to its broad(prenominal) strength to weight ratio and good toughness. Furthermore, good corrosion resistance of duralumin makes it so suitable to be used under harsh condition. However, in 1950s, a fully loaded De Havilland Comet jet airliner crashed due to metal fatigue. This gave rise to demand of materials suitable for aircrafts primary structure with high fatigue resistance.English scientist, Norman de Bruline, was the depression to propose the use of composite materials in aircrafts structures.Then, more and more composites were introduced to suit certain requirement of properties of aircrafts structure. modern font fibers, such as carbon-reinforced fibers, Kevlar aramid, glass-reinforced fibers and boron fibers, are the stiffest and strongest materials known. (Composites Manufacturing, 2006)Modern CompositesComposites are well known for their favorable properties such as high strength to weight ratio, high stiffness, very high stress level, high fatigue resistance and good corrosion resistance. Some of the widely used composites in aircraft structures will be discussed below.In common, all composites are made of relatively untoughened bonding of lamination of materials. Hence, core in composite laminate is introduced to increase the laminates stiffness by effectively thickening it with a low- assiduity core material. This can provide a dramatic increase in stiffness for very little additional weight, where lightweight implication is so crucial for aircraft structure.For example, application of honeycomb core provides stronger uphold resistance to composite la minates. With its hollow cells, it provides good energy absorption and sound dampening effect to the laminates.TypesThere are many types of composites currently used in aircraft structure. However, in this part only carbon fiber, fiberglass and Kevlar aramid will be discussed.Carbon FiberCarbon or graphite fiber is basically fiber that contains more than 90% of carbon. Carbon fibers are ideal for lightweight reinforcement, as well as high strength, high stiffness application in aircrafts structure, due to its unique combinations of properties. High-performance carbon fibers are available in a range of properties, product forms, and prices. Most of the Carbon Fibers are made from organic polymers, with irons of carbons connected to each other, such as polyacrylonitrile (PAN). (Composites Manufacturing, 2006)FiberglassFiberglass is a reinforcing material that is widely used in aircraft structure. More than 70% of the reinforcement of thermoset resins is made of fiberglass. In genera l, the longer the fibers, the greater the strength of the fibers is. And continuous fibers are the strongest amongst all.Glass does not burn, and at high temperature glass retains its mechanical properties, up to 50 per cent of its strength at 700F. Furthermore, glass has excellent moisture resistance compared to metals. Thus, it is suitable for application on aircraft structures.Lime-alumina-borosilicate glass, or E glass, was the first glass essential specifically for continuous fibers production. It is designed for electrical applications, with its good adaptability and high effectiveness in processes and products, ranging from decorative to structural applications in aircrafts. (Composites Manufacturing, 2006)Kevlar AramidKevlar aramid, introduced commercially in the 1970s, is an aromatic long-chain polymeric amide polymer produced by spinning using standard textile techniques. It was introduced to replace steel in racing tires.Kevlar aramid is well known for its high tensile strength, low density and good impact resistance with about half the stiffness of graphite structure. These properties offer a better choice for materials used in aircraft structures. For example, Kevlar 49 aramid fiber is widely used as reinforcement for plastic composites in aerospace, marine, automotive, and other industrial applications. (Composites Manufacturing, 2006)FabricationIn general, the reinforcing and matrix materials are combined, compacted and processed to undergo a melding event. In this part, fabrication of carbon fiber will be discussed in details. Figure 1 below illustrates the brief process of fabrication of carbon fiber, from its forerunner form to the fiber.Figure 1 Fabrication Of Carbon Fiber (Flow Chart, 2010)Firstly, acrylonitrile, CH2CHCN, a chemical compound derived from propylene and ammonia, is mixed with another plastic in pulverise form, and is then reacted with a catalyst in a solution polymerization process. In results, a polymer is formed. After that, the polymer is put under spinning process to form the internal atomic structure of the fiber. This process is done by heating up the mixture and pump through tiny jets into a chamber where the solvents evaporate. The polymer is then washed and stretched to align the molecules within the fiber. This complete process is called stretching. The final product after this process is known as precursor.Next, the fibers will undergo oxidation process. The fibers are heated in air to about 200 to 300C for 30 to 120 minutes, to convert the linear atomic bonding to ladder bonding. This is to desexualise a more thermally stable bonding of fibers.After the fibers are stabilized, they are heated again to 1000 to 3000C for several minutes in a furnace. This has to be done in inert environment to prevent fibers from burning with presence of oxygen gas. As the fibers are heated, they start to lose their carbon atoms as well as non-carbon atoms while the remaining carbon atoms will form a tigh tly bonded carbon crystals that are aligned almost agree to the longitudinal axis of the fibers. This process is known as carbonization. In some processes, two furnaces are operating in two different temperatures to provide a better control of heating rate.Lastly, the fibers will undergo surface treatments such as oxidation to provide better bonding properties, coating to protect fibers from external damage. (Composites Manufacturing, 2006)Technical EffectsGenerally, composites are superior in fatigue resistance, corrosion resistance, and high strength-to-weight ratio. These properties give composite aircrafts better fuel efficiency as well as better load capacity, as compared to the metal alloy counterseparate.In addition, composites design offers lower maintenance cost compared to that of metal alloy design. Composite parts are manufactured as a whole, compared to metal parts are manufactured in the form of sheet metals and are connected by message of fasteners, the former grea tly reduce maintenance cost by simplifying maintenance procedure. Figure 2 below shows the fuselage barrel section being manufactured in one piece, without the needs of fasteners.Figure 2 Boeing 787 DreamLiner Fuselage (Composites Material, 2004)However, composites are not as almighty as they have been told. For instance, most composite materials are poor in electric conductivity and such, causing them to be more susceptible to damage due to lightning strikes. Compared to metal alloy airframes, composite counterparts require extra procedure in order to take care of the electric charge from the lightning as well as static charge from friction when flying.Furthermore, unlike metals, composites break without sign or physical warning. Compared to aluminum alloy, composites do not bend when subjected to impact but break once they fail to withstand the load.ApplicationsComposites are currently used widely in aerospace industry. Primary structures, for example fuselage, move, ailerons, f laps, empennage, are made of composites in modern aircrafts. For example, composites contributed 50 per cent to the weight of Boeing 787 DreamLiner, whilst almost 100 per cent of the fuselage skin and wings surface are composites. Figure 3 below illustrates the usage of composites in Boeing 787 as compared to that in Boeing 777, has increased significantly.Figure 3 Goodbye alloy Planes (Goodbye Metal Plane, 2005)Secondary structures such as pressure bulkheads, floor beams, and landing gear door are also made of composites. Furthermore, composites are also used in interior.Composites In The Futureself-importance-Repairing CompositesSelf-repairing composites are composites that are able to repair cracks on the aircrafts as they happen. Figure 4 below illustrates the fundamental of self-repairing composites. By designing a network of glass rods filled with resin, it is possible to stop the crack from propagating and repair the aerodynamics characteristic of the aircraft when crack ha ppen in flight.Figure 4 Self Healing Artificial Skin (Self Repairing, 2007)However, there are limitations in self-repairing composites, for example, the supply of the resin in the network. A system with vascular network has to be certain to resupply the resin so that self-repairing composites serve their purpose from time to time.Shape Memory CompositesShape memory composites are composites that retain one or two shapes after being cold-worked. Figure 5 illustrates how shape memory composites retain shapes after being subjected to heat.Figure 5 Shape Memory (Shape Memory, 2007)This is highly useful in aircrafts design as it means the aerodynamics of the aircrafts can now be controlled according to whether maneuverability or stability is needed.ConclusionComposites are currently used as a better material used in aircraft primary structures, substituting aluminum alloy that had been used for decades. Due to composites superiority in corrosion resistance, fatigue resistance, and wei ght saving, it is expected that incoming models of aircrafts will use composites extensively. Application of composites in modern aircrafts once again proves that composites are more reliable than metal alloys in airworthiness. However, further development of composites should be done to overcome weaknesses found currently to further improve the safety of aircrafts.

Searching for the Skeletons in the Closet: Did Richard III Have his Nep

Did Richard III Have His Nephews Killed?The reign of Richard III is something of a paradox. His rule was brief and he lost his pennant to a usurper, allowing the House of York to die with him. Yet few English kings have been the subject of such(prenominal) continuous debate, and none have spawned such fervent denigration, or such enthusiastic support. Much of the debate fuelling pro- and anti-Richardians has been whether or not Richard had his two young nephews, Edward V and Richard of York, murdered. Unfortunately to date it has been a debate mired in speculation. Writes V. B. Lamb No conclusive proof has ever come to light which could provide a solution that did not rest solely in speculation. The possibilities are endless, that all remain at best quite unsupported theories (89). Indeed, the possibilities have seemed endless. There have been myriad theories, ranging from the plausible to the completely inane. People commenting on the reckon range from Sir Thomas More to William Shakespeare to the current Duke of Gloucester. Some of these theories will be discussed in this paper. I will draw on mentations both contemporaneous and current, pro and con, along with my own insights, in an attempt to engage the sources in conversation and hopefully provide the reader with a more clear and accurate idea of Richard III and his actions (or lack thereof).Some questions are important to keep in mind when assessing the culpability of Richard. Does he seem a man capable of such a heinous act as infanticide, and his own nephews at that? Assuming he does, did the political situation make it prudent for him to do so? Or were there others who stood to gain more by their deaths?Before these questions can be answered, some context is needed. The Engl... ...ot exist he is therefore an innocent man.BibliographyGillingham, John. Introduction interpret Richard III. Richard III A MedievalKingship. Ed. John Gillingham. London Collins and cook Ltd, 1993.Hammond, P.W. The Reput ation of Richard III. Richard III A Medieval Kingship.Ed. John Gillingham. London Collins and Brown Ltd, 1993.Hammond, P.W. and Sutton, Anne F. Richard III The Road to Bosworth Field. London Constable and Company Ltd, 1985.Horrox, Rosemary. Richard III A Study of Service. Cambridge CambridgeUniversity Press, 1989.Lamb, V.B. The Betrayal of Richard III An Introduction to the Controversy.Revised Ed. Stroud Alan Sutton Publishing Ltd, 1990.Richmond, Colin. 1483 The Year of purpose (or Taking the Throne). Richard IIIA Medieval Kingship. Ed. John Gillingham. London Collins and Brown Ltd,1993.

The Revolt Of The Poor - The Demise Of Intellectual Property :: essays research papers

<a href="http//www.geocities.com/vaksam/">Sam Vaknins Psychology, Philosophy, Economics and Foreign Affairs Web SitesThree years ago I published a disc of short stories in Israel. The publishing house belongs to Israels leading (and exceedingly wealthy) newspaper. I signed a contract which stated that I am entitled to receive 8% of the income from the sales of the book after commissions payable to distributors, shops, etc. A few months later, I won the coveted Prize of the Ministry of culture (for short prose). The prize money (a few thousand DMs) was snatched by the publishing house on the legal grounds that all the money generated by the book belongs to them because they own the copyright. In the mythology generated by capitalism to pacify the masses, the myth of intellectual property stands out. It goes like this if the rights to intellectual property were not defined and enforced, commercial entrepreneurs would not have taken on the risks associated with publishin g books, recording records and preparing multimedia products. As a result, creative people will have suffered because they will have fix no way to make their works accessible to the public. Ultimately, it is the public which pays the price of piracy, goes the refrain. But this is factually untrue. In the USA there is a very especial(a) group of authors who actually live by their pen. Only select musicians eke out a living from their noisy vocation (most of them rock stars who own their labels George Michael had to fight Sony to do just that) and very few actors come close to deriving subsistence level income from their profession. All these can no longer be thought of as in general creative people. Forced to defend thie intellectual property rights and the interests of Big Money, Madonna, Michael Jackson, Schwarzenegger and Grisham are businessmen at least as much as they are artists. economically and rationally, we should expect that the costlier a work of art is to produce and the narrower its market the more its intellectual property rights will be emphasized. Consider a publishing house. A book which costs 50,000 DM to produce with a potential audience of 1000 purchasers (certain academic texts are like this) would have to be priced at a a minimum of 100 DM to recoup only the direct costs. If illegally copied (thereby shrinking the potential market some people will elect to buy the cheaper illegal copies) its price would have to go up prohibitively, thus driving out potential buyers.

What was the 1850 Compromise and Why did it Fail? Essay -- politics sl

What was the 1850 Compromise and Why did it Fail?In 1850, Henry Clay angiotensin converting enzyme of the most influential political leaders inAmerican history introduced a set of resolutions, which aimed toplease both North and South America. The five proposals were turninto a single omnibus bill, which offered a solution to the growingsectional conflict over thrall and westward expansion, which arosefrom the 1846 Mexican War. The 1850 Compromise, which Senator Douglasstripped down and effectively helped pass, failed for a number ofreasons, the greatest of which was that it was unable to please bothanti-slave and pro-slave groups. In fact it merely papered over thecrack, and did not prove, as Daniel Webster a Clay supporter hadhoped, a decisiveness that would give peace to a country long distractedby the quarrel over slavery. Why did the Compromise ultimately fail,and lead to polarization, featuring a party, which had begun to sustain itself in the 1820s.The conflict between the North and South stemmed back to 1846, whenthe U.S.A won a huge area of Mexican territory as the matter of whatbecame known as the Mexican War. The land acquired revived controversyover the extension of slavery, as many Northerners wanted the newterritory to become a free state with no slavery, and many Southernerswanted slavery to expand. Numerous compromises were conceded, to tryto resolve the sectional conflict, for example the Wilmot Proviso of1846 attempted to exclude slavery from any territory gained as aresult of the war. The Calhoun Doctrine issued in 1847, and known asThe Platform of the South, asserted that the territories were commonproperty of all the states. until now the argument of whether slaveryshould be... ... of the affects to their economy. However many Northernerswho did resist slavery probably had a free labour ideology thatNorthern farmers could grown cotton to send away the trade industries ofthe North, as a replacement for slave labour.The events that ha d occurred before and after 1846 had shown thatexpansion of America created major sectional conflict and jealousies,due principally to the unbelief of slavery. The resolutions hadactually managed to delay the immediate danger of sectional split.However as the apparent fairness of the Compromise was false, like allother attempts at compromise it failed. Slavery was a moral issue,which proved that more than a compromise was needed to resolve it. TheCompromise of 1850 ultimately resulted with a large number ofSoutherners seceding from the union, what is more politicalpolarization of the Democrats.

Relational Database Model :: essays research papers

Comparing and Contrasting the Relational Database Model and OO ModelThe relative database model is based upon remits or relations. In this model, the physical death penalty of the database is abstracted away from the user. Users query the database using a high-level query language, such as SQL. The relations are made up of columns, which have headings indicating the place represented by that column. Tables have key fields, which can be used to identify unique records. Keys relate tables to each other. The rows of the relation are also called tuples, and at that place is one tuple component for each attribute or column in that relation. A relation or table name, along with those relations attributes, lick up the relational schema. Relational Database models are server-centric.When designing a Relational Database, you must create a table for each entity type, choose or create mentally a primary key for each table add foreign keys to represent one-to-many relationships create new tables to represent many-to-many relationships define referential integrity constraints pronounce schema quality and make necessary improvements and choose appropriate data types and value restrictions for each field (if necessary).The real power of relational systems lies in the competency to perform complex queries over the data. Relational systems are well understood, and can be highly optimized in terms of queries, scalability, and storage. There is a uniqueness of table rows and primary keys, as well as ease of implementing future data model changes flexibility and maintainability. To build an effective and efficient application in the relational model, the developer must have a comprehensive knowledge of the tables, and any relationships among them.Object oriented database management systems are viewed as an alternative approach to meeting the demands of more complex data types. The need to handle complex object-centric data as the main data element is the driving forc e behind Object oriented database models. These systems attempt to extend Object Oriented programming languages, techniques, and tools to provide a means to support data management tasks. Object Oriented models are lymph node centric. Object Oriented databases uses attributes containing object identifiers to find objects that are related to other objects.When designing an Object Oriented model, you must first determine which classes require unflinching storage define persistent classes represent relationships among persistent classes and choose appropriate data types and value restrictions for each field.Object Oriented database models approach from the opposite concern (a programming language itself) to solve the problem of handling complex data types.

Harriet Beecher Stowes Uncle Toms Cabin - The Book that Started a War :: Uncle Toms Cabin

The Book that Started a War Uncle Toms Cabin, also called Life Among the Lowly, was written by Harriet Beecher Stowe. It is a realistic, although fictional view of slavery. The main characters in this story atomic number 18 Uncle Tom, Eliza and George Harris. Uncle Tom is a pious, trusdeucerthy, slave. He never wrongs anyone and always obeys his master. A very weird person, Uncle Tom tries his best to obey the Bible and to do what is right. Eliza is a beautiful slave owned by George Shelby, Sr., the same person who initially owns Tom. Eliza has a son, Harry. Elizas husband, George Harris, lives on a nearby plantation. George is a brilliant man, and invented a machine that was used in the factory he works in. His owner became jealous and demoted George from his factory gambol to doing hard labor on the plantation. This story takes place throughout the states of Kentucky and Mississippi. Chapters 1-5 Because his Kentucky plantation was overwhelmed by debt, George Shelb y, Sr. makes plans to trade some slaves to a slave dealer named Haley in exchange for debts being canceled. The dealer selects Uncle Tom as payment for the debt. While the two are discussing the possible transaction, Elizas son, Harry, comes rushing into the room. Haley decides he wants to take Harry also, moreover Shelby refuses to part with the child. Eliza, overhearing part of the parley, is frightened and confides her fears to her husband, George Harris. The fact that Georges owner is mistreating him, combined with a possible sale of his son persuades George to begin planning to run away. After inferring from an overheard conversation between Mr. & Mrs. Shelby that they are indeed going to sell Harry and Uncle Tom, Eliza warns Tom and she runs away. Chapters 6-15 Eliza is able to cross the Ohio River and get to a safe place before Haleys two hired slave-catchers can catch up with her. Although he was warned, Uncle Tom stays on the plantation, leaving it up to God to pro tect him. At the same time, George Harris begins his escape. draped as a Spaniard, George takes his time finding a route on the underground railroad. He just happens to go to the same place where Eliza and Harry are being hidden.