Convection Currents and How They Work

Convection currents are flowing fluid that is moving because there is a temperature or density difference within the material. Because particles within a solid are fixed in place, convection currents are seen only in gases and liquids. A temperature difference leads to an energy transfer from an area of higher energy to one of lower energy. Convection is a heat transfer process. When currents are produced, matter is moved from one location to another. So this is also a mass transfer process. Convection that occurs naturally is called natural convection or free convection. If a fluid is circulated using a fan or a pump, its called forced convection. The cell formed by convection currents is called a convection cell or  Bà ©nard cell. Why They Form A temperature difference causes particles to move, creating a current. In gases and plasma, a temperature difference also leads to regions of higher and lower density, where atoms and molecules move to fill in areas of low pressure. In short, hot fluids rise while cold fluids sink. Unless an energy source is present (e.g., sunlight, heat), convection currents continue only until a uniform temperature is reached. Scientists analyze the forces acting on a fluid to categorize and understand convection. These forces may include: GravitySurface tensionConcentration differencesElectromagnetic fieldsVibrationsBond formation between molecules Convection currents can be modeled and described using convection-diffusion equations, which are scalar transport equations. Examples of Convection Currents and Energy Scale You can observe convection currents in water boiling  in a pot. Simply add a few peas or bits of paper to trace the current flow. The heat source at the bottom of the pan heats the water, giving it more energy and causing the molecules to move faster. The temperature change also affects the density of the water. As water rises toward the surface, some of it has enough energy to escape as vapor. Evaporation cools the surface enough to make some molecules sink back toward the bottom of the pan again.A simple example of convection currents is warm air rising toward the ceiling or attic of a house. Warm air is less dense than cool air, so it rises.Wind is an example of a convection current. Sunlight or reflected light radiates heat, setting up a temperature difference that causes the air to move. Shady or moist areas are cooler, or able to absorb heat, adding to the effect. Convection currents are part of what drives global circulation of the Earths atmosphere.Combustion generates conv ection currents. The exception is that combustion in a zero-gravity environment lacks buoyancy, so hot gases dont naturally rise, allowing fresh oxygen to feed the flame. The minimal convection in zero-g causes many flames to smother themselves in their own combustion products.Atmospheric and oceanic circulation are the large-scale movement of air and water (the hydrosphere), respectively. The two processes work in conjunction with each other. Convection currents in the air and sea lead to weather.Magma in the Earths mantle moves in convection currents. The hot core heats the material above it, causing it to rise toward the crust, where it cools. The heat comes from the intense pressure on the rock, combined with the energy released from natural radioactive decay of elements. The magma cant continue to rise, so it moves horizontally and sinks back down.The stack effect or chimney effect describes convection currents moving gases through chimneys or flues. The buoyancy of air inside and outside of a building is always different due to temperature and humidity differences. Increasing the height of a building or stack increases the magnitude of the effect. This is the principle on which cooling towers are based.Convection currents are evident in the sun. The granules seen in the suns photosphere are the tops of convection cells. In the case of the sun and other stars, the fluid is plasma rather than a liquid or gas.

Abuse of Power in Heart of Darkness and in Frankenstein

How is the abuse of power shown in two works that you have studied? The works I have studied and will be exploring in this essay are Mary Shelly’s ‘Frankenstein’ and Joseph Conrad’s ‘Heart of Darkness’. In ‘Frankenstein’ the abuse of power is most clearly exhibited by the protagonist of the story Frankenstein himself, his abuse of power results in his isolation and could serve as a warning to people, telling them not to play with forces that they can not control. In ‘Heart of Darkness’, Conrad abuses his power as the author to distance himself from the novella and in a sense absolve himself from any racist criticism the book may induce. The abuse of power is also a key theme in the novella itself. Firstly there is a sense of hypocrisy in†¦show more content†¦King Leopold was abusing his position of power to exploit the Congo for it’s raw materials, it can be said that the vivid cruel and gruesome images Conrad conveys in the book are merely mirroring the harsh reality of the brutalisation in Africa. One could therefore conclude that due to Conrad’s own experiences in the Congo he has to tell his story through a framed narrative, as it may be too difficult for him to share his story in the first person. Whether this was the case or not, it is clear than in ‘Heart of Darkness’ Conrad reveals the abuse of power to be ever present in the colonial age that Conrad lived in, and he demonstrates the abuse of power as something to be wary of and to fear, as it can result in madness. Finally the abuse of power in the Congo also demonstrates the hypocrisy of Imperialism through the corruption observed in ‘the company’. Before Marlow travels to the Congo itself he reveals that it was very difficult for him to ascertain a job, which would result in his exploration of the river which had charmed and fascinated him from childhood. It is at this point that Marlow decides to ask his aunt for help, and she manages to get him a job, which will take him where he desires to go. This clearly demonstrates that Marlow’s abuse of power right at the beginning of the book. He then proceeds to judge others who are abusing power when he is in the Congo. ForShow MoreRelatedComparative Studies of Bladerunner and Frankenstein1157 Words   |  5 PagesCompare the ways in which texts offer insights into the human experience. Every text is a product of its time. In Mary Shelley’s â€Å"Frankenstein†, she uses the gothic horror genre to explore some of the concerns of her time relating to the use of science and technology and its impact on humanity. 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Unfortunately for the sisters, their family has developed a pattern: The issues of the previous generation have been passed down with the next generation, creating a legacy of substance abuse, an unstable home environment, suicide, and mental illness. In this setting, the sisters must react to the troubles they witness around them daily, for their parents and other family are unable to shield the girls from the fallout of their emotionalRead MoreHomosexuality in Victorian and Elizabethan Literature.6608 Words   |  27 Pagesand managed to reverse them, making men faint like women, and making women powerful like men, and called it Dracula. Mary Shelley created a a physical being out of a mans suppressed homosexuality due to his Victorian male u pbringing; a man named Frankenstein. Robert Stevenson described what happens when a homosexual male attempts to live double lives to cover up his true feelings, and entitled it The Strange Case of Dr. Jekyll and Mr. Hyde. 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So they play Boo Radley a game where they try and reenact the demise of Boo Radley. My personal outlook on the events prescribed in the chapter. On page 34, when AtticusRead MoreLogical Reasoning189930 Words   |  760 Pagescannot. a. yes b. no c. cant tell ââ€"   2. Is the following conditional true? If kids who are abused usually become abusive parents when they have children, and John Drew is being abused by his mother, then when he grows up he is likely to abuse his own children. a. yes b. no c. need more information to tell54 3. If the if-part of a conditional claim is true, and if the conditional claim itself is true, will the then-part have to be true? 4. Is the following statement an argument

Comparing the Spanish and English Colonies in the New World free essay sample

The Spanish settlements in the American Southwest and the English colonies in New England of the seventeenth century can be contrasted in primarily two ways. First, their politics were based on entirely different ruling classes and systems of government. Second, they employed different avenues of economic development. The Spanish settlements began with Cortes and others conquering the Native Americans of South, Central, and parts of Southwestern North America. After eradicating a large portion of the Native American population, the Spanish began to intermarry into the Native American gene pool. Consequently, only portions of the population were pureblooded Spaniards. These Spaniards occupied the highest social and political status. Those from Spain were one step above those born in the New World while those of mixed or Indian heritage were at the bottom of the social ladder. Additionally, because the Spanish came as conquerors, the resulting political system was entirely autocratic and solely devoted to the furthering of the motherland. We will write a custom essay sample on Comparing the Spanish and English Colonies in the New World or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Immediately after conquering the Native Americans, the Spanish looted large amounts of gold, silver, and other valuables. This tradition continued into the seventeenth century as Spanish ships would come annually to bring gold and other valuables back to Spain. In this way, Spain viewed Spanish America as an object useful only for its mercantilist objectives. Since mercantilism was its only objective, Spain gave its colonies little self-rule. Instead, Spanish rulers dictated all the policies of its New World territories. The English, on the other hand, settled relatively peacefully into the Eastern Seaboard of North America. Englishmen migrated to the New World not as conquerors but rather because they wanted independence, political freedom, and economic opportunity. Combined with Englands tradition of partial representation, the English Colonies had a large degree of self-government. The colonies all had some form of a representative assembly that was voted in by popular support. While only white male landowners could vote, this still constituted some degree of democracy. In some colonies, even the governors were decided by popular vote. Also, many of the British colonies, such as Virginia, were established by joint stock companies or established as proprietary colonies, such as Pennsylvania. Even royal colonies were often simply colonies given a royal charter but still established by a group of people not directly affiliated

Towards the Conceptualization of a Nonâ€Linear ISD Model

Introduction Over the years, a multiplicity of instructional design models have been suggested, and many of these models have been incorporated into mainstream educational institutions for purposes of aiding instruction and directing the learning process. In their study on developing a multimedia package for teaching qualitative research, Colon et al (2000), noted that over 200 instructional design models have been proposed and indeed published in some of the widely read educational literature.Advertising We will write a custom research paper sample on Towards the Conceptualization of a Non–Linear ISD Model specifically for you for only $16.05 $11/page Learn More Many of the models, however, are oriented towards behaviorist and constructivist theories of learning, leading to accusations and counter-accusations by a number of leading scholars that the models impede the true nature and scope of learning not only due to their behaviorist point of ref erence, but also due to their signature top-down linear and sequential processes (Colon et al., 2000). In the light of the above and other accusations, this paper aims to demonstrate how a non-liner instructional systems design (ISD) model can be conceptualized for instruction. Why a Non-Linear ISD Model Existing literature demonstrates that employing an ISD model can be helpful to instructional designers in assisting them to systematically identify what is to be taught, establish the best teaching methodologies that can be used, and appraise the instruction to determine its effectiveness in fulfilling the tasks and objectives for which it is intended (Kanuka Anderson, 1999). The Instructional Systems Design Model developed in 1996 by Dick and Carey has indeed proved to be popular among instructional designers in providing a framework through which instruction is provided to learners. This particular model is solidly â€Å"†¦based on one form of systems theory, as well as beh avioral and information processing theories of learning† (Colon et al., 2000, para. 12). However, due to the convergence of technology, changes in the education system, and new and unique needs projected by learners, this and other linear models for instruction design continue to attract criticism from various quarters. According to Gayeski (1998), inadequacies and ineffectiveness exhibited by these models, especially in learning and performance improvement environments has called their practicability into question.Advertising Looking for research paper on education? Let's see if we can help you! Get your first paper with 15% OFF Learn More Critics have also faulted the sequential, systematic, teacher-led, and top-down approach employed by linear ISD models largely due to the fact that they relegate learners to the role of passive participants, not mentioning the fact that most of these models do not provide room for innovation and active feedback (Colon et al, 2 000). While it is critically important for educators to clearly identify the learning objectives and systematically sequence them from least complex to the most complex (Kanuka Anderson, 1999), the linear approach employed locks out many students from applying the knowledge learnt to solve contemporary practical solutions by virtue of the fact that learning objectives exist irrespective of the contributions made by the learner. The models are further criticized for assuming an overly behaviorist and constructivist orientation in instruction and ignoring other methodologies that can effectively be used to transfer knowledge (Mergel, 1998). There is, therefore, a compelling need to devise non-linear ISD models to ensure optimal transfer of practical knowledge from the educator to the student. Model Phases and Linkages The conceptualized ISD model heavily relies on R2D2 model developed in 1995 by Willis and Merrill’s First Principles of Instruction developed by David Merrill (C olon et al., 2000; Merrill, 2002). The model has 6 phases, namely, problem identification, recursion, reflection, activation, participatory application, and integration. The problem-centered ISD model first identifies the problem and develops a set of objectives used to solve the problem. The set of objectives developed in this model are likely to change depending on the needs of individual learners, hence the need to create a link between the problem identification and the recursion and reflection phases (see appendix 1). According to Merrill (2002), â€Å"†¦learning is activated when learners are engaged in solving real-world problems† (p. 43). The recursion phase will aim to specifically allow instruction designers and learners to revisit any phase included in the model to make refinements, corrections, and revisions as deemed necessary. This will actively promote the learning process in addition to ensuring holistic integration of new knowledge by the learners. This phase is also linked to problem identification phase, reflection phase and integration phase.Advertising We will write a custom research paper sample on Towards the Conceptualization of a Non–Linear ISD Model specifically for you for only $16.05 $11/page Learn More The next phase – reflection – is intended to emphasize the need for the instruction designers to considerately inquire about feedback and other arising notions from other sources, including the learners’ own perceptions, worldviews and level of understanding (Cohen et al., 2000). Further on, activation phase will take cognizance of the fact that â€Å"learning is promoted when relevant previous experience is activated† (Merrill, 2002, p. 46). Many learners have had many previous experiences that may relate to the task at hand and, as such, relevant information should be activated by going back to the reflection phase to ensure this information is elicited fo r use as groundwork for learning new knowledge. The participatory application phase is where real learning takes place. This phase takes note of the fact that it is the learners who will utilize the knowledge transferred by educators, and they must therefore be active participants in the learning process (Cohen et al., 2002). As such, this phase will also be linked with other phases such as problem identification and reflection to guarantee the involvement of learners. In this phase, educators must develop frameworks aimed at ensuring that learning process is consistent with the identified methodologies of solving the problem, and that learners have the capacity to utilize the new knowledge in solving practical problems. The integration phase will focus on ensuring that learners have the capacity to integrate the knowledge transferred by the educators to solve their everyday problems (Merrill, 2002). This phase will also be linked with reflection and recursion phases to ensure all a rising queries from the learners are adequately attended to (see appendix 1). Model Outputs The outputs for problem identification phase include the objectives and the methodologies that will be used to solve the underlying problem. The recursion phase will generate problem refinements, corrections, and revisions as may be deemed necessary. The reflection phase will generate feedback from instructors and students, and learners’ perceptions and worldviews concerning the problem at hand.Advertising Looking for research paper on education? Let's see if we can help you! Get your first paper with 15% OFF Learn More The activation phase will aim to come up with quantifiable measures that can be used to evaluate the capacity of learners to grasp and relate to the problem at hand, while the participatory application phase will generate the actual results of the learning process, including how the learner has understood the problem and if there is need to make clarifications. The outputs arising from the integration phase include the practical demonstration by learners on how they can use the knowledge learnt to solve real-life problems, and the capacity by learners to link the knowledge learnt to other life experiences. Structure of Model The model utilizes a non-linear structure to avoid the many problems associated with linear ISD models. This particular model realizes that different problems may call for diverse starting points, and new objectives may indeed emerge over the design process (Cohen et al., 2002). As such, it is important to create mechanisms for adequately address arising issues that are largely ignored in linear models. Conclusion The need to conceptualize and develop a non-linear ISD model is very much informed by the urge to come up with practical solutions to the many challenges facing instruction especially in contemporary times. Learners need to be assisted to solve practical solutions using an instruction strategy that is responsive to their needs, and that realizes their participation is important for effective learning to take place. In addition, the complex nature of modern problems and instruction have rendered most linear ISD models ineffective due to entrenched limitations in scope and practicability in offering an instruction methodology that can assist learners to relate what has been learned to real-life experiences (Merrill, 2002). The conceptualized non-linear ISD model will not only ensure that learners can use new knowledge to solve practical issues, but it will avail platforms for recursion and participatory application. Appendix 1: An Illustration of Non-Linear ISD Model References Colon, B., Taylor, K.N., Willis, J. (2000). Constructivist instructional design: Creating a multimedia package for teaching critical research. The Qualitative Research, 5(1-2). Web. Gayeski, D.M. (1998). Out-of-the box instructional design: Moving from assembly-line models to non-linear performance models. Web. Kanuka, H., Anderson, T. (1999). Using constructivism in Technology-Mediated Learning: Constructing the Order out of the Chaos in the Literature. Web. Mergel, B. (1998). Instructional Design Learning Theory. Web. Merrill, M.D. (2002). First principles of Instruction. ETRD, 50(3), 43-59. Web. This research paper on Towards the Conceptualization of a Non–Linear ISD Model was written and submitted by user Nadia Horton to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.