Theoretical Perspective Research Paper Example | Topics and Well Written Essays - 1000 words

Theoretical Perspective - Research Paper Example Project managers usually use emails and video conferencing techniques for a two way communication with his team members. Apart from this, special 3D and 2D satellite images are used by project managers for detecting the areas of oil spills and the working condition of the pumps. The manager then schedules the maintenance plan for the same. The oil and gas field can also be detected under the sea or on ground through 3D images of Stereo satellites. The companies are injecting the most advanced technologies to increase the efficiency of the workforce and also maximize the profit. Increasing use of these VPM tools is also helping the industry to decrease their operating expenses and this might also affect the price of oil and gases in the global market in future. Table of Contents Virtual Project Management 4 Virtual Project Management (VPM) Tools 4 VPM Tools in Oil Producing Environment 5 Current and Future Abilities for Project Implementation 6 Effect of New Technology on Projects and Members round the World 7 References 8 Virtual Project Management We often see that, the project teams are generally dispersed in many different locations of the world. The projects in MNCs are generally given to team, in which the members might be working from different parts of the world. Sometimes a single project is carried out by different companies. The geographically dispersed work or project is often called virtual projects. Virtual projects are called so because most of the communication regarding the project is done through email, video conferencing, telephone or using other forms of technology. The long distance communication methods and techniques are no longer expensive or prohibited. It helps the project managers to communicate with his project team frequently and openly (Mantel, Meredith, & Shafer, 2006, p. 56). Virtual Project Management (VPM) Tools In Virtual Management, the whole team is mainly depended upon the technological aspects. As such most of the work and decision making functions are undertaken through web-based technology such as internet. The tools that are used in virtual project management need to fit in the teams from all round the world. The main function that any VPM tool should have, is to allow the project team members to communicate with one another efficiently, as all the team member are in separate locations. Moreover, they might not have knowledge of each other's prior work experiences. In this case communication becomes the only key for discussing and formulating plans regarding the project. Secondly, the tools should also allow the team members to collaborate in the virtual space. The tools should also help the project manager to manage the project functions, schedule the resources and also track the progress of the tasks. The VPM tools are usually web based applications, which are used to create schedules and assign tasks. The resources and activities of team members are monitored and important documents are also exc hanged through these tools. VPM Tools in Oil Producing Environment Virtual project management tools are very useful in the field of natural resources such as minerals, oil and gas. Since, these natural resources are usually found in remote areas, so technological tools play a very important role in detecting and planning out the projects. In such cases, satellite, and airborne remote sensing technology is often used to select the oil and gas

Hume and his contemporaries Essay Example for Free

Hume and his contemporaries Essay Live art performances, marked by an overture of spirituality, consciousness, physical introductions to pain, drawn further on to include specific rituals, symbolisms, varied states of emotions brought by self-inflicted hurt and eventually, culminating in a wild display of frenzy and shocking images, are less likely to please the uninitiated audience than it will provoke a sense of awe and wonderment among performance art critics. In a similar situation, Marina Abramovic’s attempts to upend the static discourses of physicality, mental states of mind and art that pervade current Western hegemony, understandably, can only be regarded in the extremes by people steeped firmly into formal traditions. Either her method of performance will elevate its spectators to a heightened degree of appreciation, therefore merit a thunderous welcome to a novel brand, sui generis, of art of our time at the end of each scene; or her gruesome didactics on the body’s threshold for pain, simply fails to pass muster. Her performance practice, a risk more than anything else, certainly inspire debates on whether or not to set moral, perhaps even social limits to art in order to determine, in precise and concrete terms, at which point creativity and imaginative art themes and performances become either delightful to the senses or noxious to the sensitivities of the general public. The idea of drawing the line along and between different shades of extremes, although already evinced clearly in the works of Marina Abramovic, seems to fit the consensus on the idea of censuring the bold and burlesque, stripping it off its material enunciation and expression to mitigate the horror and revulsion inherent in the exposition, or in the worst case, totally ignore it until the novel yet misunderstood facade fades from inattention. However, thanks mainly to Marina Abramovic’s unwavering desire to reach her audience, despite the sometimes hostile reception during her performances itself, in ways that continually push the envelope of spectator tolerance, did she carry her work from the esoteric art circles to mainstream. To wit, in one of her collaborative performances with Ulay, entitled Incision (1978), while purposively eliciting reaction, probably direct participation, from their audience, one of the spectators primed the climactic resonance of the work by jumping into the stage to kick Marina Abramovic as she was lying prostate right in the middle of the act. In her biographical work, she writes that although she expected the attack to happen any moment during the performance, she did not realize the immediacy and steeled resolution of that man who assailed her (Abramovic, 1998). Photographs of the show caught the man with a leg lifted, jumping into the air. â€Å"The next photograph shows Abramovic lying on the floor, and the man seems to be landing from a kicking action [†¦] the audiences interrogation manifested in a spontaneous physical attack (Tang, 2005). Ethical and moral questions, as well as aesthetic controversies have been discussed quite animatedly as early as the 18th century. Philosophers, like David Hume, have started to addressed the tough issues about morality, art and taste—the chief concerns that pervaded his era. Cynthia Freeland, introducing the notions of Taste and Beauty, in a book about defining the slippery strands of art, writes that Hume and his contemporaries â€Å"would not have approved of blasphemy, immorality, sex, or the use of body fluids as appropriate in art† (Freeland 2001). As a caveat to this general statement, it must be understood that even though 18th century consciousness all the way up to the present have not been too open in giving cognizance to art that smack of Marina Abramovic’s own brand of carnal art expressions, there are already extant cultural and social systems which places importance into shamanistic and ritualistic gestures. Among art critics and historians, some pursue a theory of art as ritual: â€Å"ordinary objects or acts acquire symbolic significance through incorporation into a shared belief system† (Freeland, 2001). In the same vein, Freeland further digs deep in history to provide evidence in varied cultural rituals that depict blood and physical pain. She avers that â€Å"when a Mayan king shed blood before the multitude in Palenque by piercing his own penis and drawing a thin reed through it three times, he exhibited his shamanistic ability to contact the land of the undead† (2001). Other modern artists try to recreate a similar sense of art as ritual, just as much as Marina Abramovic has had for the last three decades. Diamanda Galas, for instance, â€Å"fuses operatic wizardry, light shows and glistening blood in her Plague Mass† (2001), supposedly to exorcise pain in the era of Aids. Herman Nitsch, Viennese founder of the Orgies Mystery Theater, promises â€Å"catharsis through a combination of music, painting, wine-pressing, and ceremonial pouring of animal blood and entrails† (Nitsch, n. d. in Freeland, 2001). As it turns out, these very rituals are ingrained in Western traditions. Illuminating examples of which are the amount of blood depicted in European’s, and verily much of the cultures in the modern world today, two main belief discourses: that of the Judeo-Christian and the Greco-Roman. By taking a cursory review of religious and classical texts of Western traditions, we are able to immediately uncover a plenitude of blood representations and ritualistic sacrifices. In the Old Testament, Yahweh is seen to require â€Å"sacrifices as parts of His covenant with the Hebrews† (Freeland, 2001). Similarly, Agamemnon â€Å"faced a divine command to slit the throat of his own child [†¦] the blood of Jesus is so sacred that it is symbolically drunk to this day by believing Christians as promising redemption and eternal life† (2001). Such myths and religious stories are rather germane to Western art. We read of Homeric heroes wining the favors of their gods and goddesses by sacrificing animals. Likewise, the tragedies of Lucan and Seneca â€Å"piled up more body parts than Freddy Krueger in A Nightmare on Elm Sreet† (2001). Not surprisingly, likewise, Renaissance paintings are never without a hint of blood draped at the canvassed in hard red-acrylic paint whilst Shakespeare’s tragedies typically concluded with swordplay and stabbings. The preceding examples of ritualistic performances which involves blood and sacrifices, death and disease, murder and trials, are very instructive with regards to our penchant for the macabre and the dreadful. It is in these premises that Marina Abramovic draws much of her inspiration to create an art, pro forma, that bespeak of our capacity to endure scenes of gore and violence—if only on a less exacerbated state. Her performance, for the most part, certainly places importance on the symbolic values of ceremonies, gestures and artifacts. Albeit appearing random and spontaneous, her methods establish a logical connection between her consciousness while performing and her body’s means of coping with the strength of self-infliction. In the nascent days of her art, she has performed controversial after controversial explorations into the limitations of the mind and the body. Rhythm 10, in 1973, was the first in a series of abject surrender to the inevitability of suffering. Alone in the stage, she prepared a set of knives to be used as piercing objects in a risky game of Russian hand roulette. Without signs of hesitation, she proceeded to stab the spaces between her fingers in a rough yet determined fashion. Each time she made the mistake of cutting her flesh; she dropped the knife and took out another one to repeat the process all over again until she made use of all ten knives (Abramovic, 1998). The following year, in the performance entitled Rhythm 5, she sought to re-evoke the energy of extreme body pain by constructing a huge star soused with combustible petroleum liquid. At the onset, the structure as lit to flames, and while she was standing right outside the contraption, she religiously clipped her fingernails, cut her hair and them inside the burning star. The denouement of the program was when she danced around and then flew across the flames into the center of the burning star. Serious and life-threatening complications ensued when the smoke that engulfed her from inside asphyxiated her to the point that she no longer had control of her actions. The medical team and the audience, who were all there to watch, started to suspect that something was terribly amiss. Fortunately, the quick responses from the stand-by technicians saved her from an untimely death caused by severe smoke inhalation (Abramovic, 1998). In the same year and the years that followed, Marina Abramovic designed similar art experiments that were meant to test the limits of herself and her body, and later the audience and their tolerance for vicarious agony through her body. Rhythm 2 and Rhythm 0, were performed with the hopes of proving that the consciousness can go beyond the rubric of psychological triggers in mind. The sole aim of both was to uproot the inherited tendencies of the mind to reel from stark images and provocative gestures. She sought to cultivate in the audience a sense of indifference in order that one may reach a virtual catharsis what with all the sharp and strong representations between the body and suffering. For artists like Marina Abramovic, it is clear to them that what they are performing, and while in the act of performing, there is a higher purpose that they wish to achieve regardless of the methods by which these are made possible. They have a firm understanding and appreciation for every act and gesture that they make. None of such are done without rhyme and reason. For artists like Marina Abramovic, everything that happens during any performance, in spite of the harsh opinions of critic that meet them right afterwards, makes a lot of sense. However, audiences who see and react to these artists do not enter, much less share the beliefs and values, or with prior knowledge of what will transpire, with that of the artist. When asked about the origins of her creativity and ideas for her art performance, Marina Abramovic happily recalls her childhood memories with her parents. As if to show indeed that her style was a result of previous life experiences that may be susceptible to a psychoanalytical reading, she narrates: â€Å"A long time ago I made a piece called Art Must Be Beautiful, Artist Must Be Beautiful. At that time, I thought that art should be disturbing rather than beautiful. [†¦]My life is full of such contradictions. [†¦] My father and mother are divorced. As an adult, I recently wanted to go back to help them because of the war. With the embargo, there is nothing in the stores. [†¦] I called my father to ask him what he needs, and he dictates a long list antibiotics, bandages, penicillin, toilet paper, coffee, sugar, powdered milk, all these basic things for survival. Then I call my mother and ask what she needs. She says, I need Chanel lipstick, Absolute Red, Number 345, and hair spray. I am between these two. † (Abramovic, 2005) Most modern art, in this case, within the context of theatre, videos and live performances, fail to provide ample background reinforcement against the dominant traditions and systems of belief. What invariably happens is that the audiences will remain ignorant to, consequently, unappreciative of the complexities and undertones of the supposedly artful, meaningful and profound gestures. The audience, instead of sharing that same degree of catharsis, sacrifice and initiation, will shy away. They themselves are alienated from the performance so much that they are brought far afield the community, forcing them to abandon the art because of pure shock and horror, largely as a result of their ineligibility to feel as the artists do (Freeland, 2001). Damien Hirst, the ‘Britpack’ artist who sparked controversy in the 1990s with his motley display of macabre high-tech exhibits of â€Å"dead sharks, sliced cows, or lambs in glasses of formaldehyde, [†¦] has parlayed his notoriety into success with his popular Pharmacy restaurant in London† (Freeland, 2001). By no means, therefore, are the works that revolve around symbolisms, spirituality, humanity and fatalism seldom reflects the nature of most of our ritualistic traditions. Symbols of pain and suffering that are central to many religions, cultural systems, political and social units, may come off to the lay person as undesirable and may even cause the same panic as had the man in Marina Abramovic’s performance. Art performance that utilizes imageries that hint at violence, torture and distress, when it is performed in the public who has no inkling of its context, meaning and history are in danger of misconstruing art for capricious display of filth and tripe. As with all in theatre, the performer must work against mutual projection between audience and performer, the identification in which [we] believe so readily in the other as the keeper of our treasure and our disease (Tang, 2004). Valie Export, a similarly omnipresent and provocative figure in the world of art performance, shares the same problems of audience interaction, although not as much as Marina Abramovic. Beside art performance, her repertoire includes film, text, painting and photography to name a few. These avenues of artistic expression gravitate towards her criticisms for feminism and gender. A staunch activist and a progressive performer, she has oftentimes been called a woman living an anachronistic life. This is due to her revolutionary ways to present her ideas that even her colleagues, who without proper notice of her intentions to perform, usually end up dismissing her as too fanciful and idealistic. Her works on ‘Asemie or the Inability of Expressing Oneself Through Facial Expressions’ (1973) and ‘Touch Cinema’ (1968) garnered both fame and distress. Chief of the reasons that contributed to an admixture of reception from the critics and audience is the fact that her ideas do not create strong meaningful associations that the people can readily identify with. Humor and parody may be part and parcel of her work as a performer, but these effects are not what she contemplated to be so. Indeed, while she wanted to catch the attention of her spectators, her ultimate goal is to instruct them of the subtle messages regarding feminism, modernism and ritual art. Export, along with the controversial artists at the turn of the 21st century, became (in-)famous in the recent decades because of her startling presentations of objects and her body (Mueller, 2004). Of her earlier works, ‘Aktionshose: Genitalpanik’ or ‘Action Pants: Genitals in Panic’ (1968), Export engaged the audience, piquing their imagination and belief, with a series of photographs, simultaneously permitting them to engage her as the tangible representations of the images presented in the collage. In an art theater in Munich, dressed to the nines, with the crotch cut out of her pants, Valie Export threaded each row person-to-person, showed her outfit thereby giving the film-viewing public with a palpably visual representation with a real female body. In doing so Export tackled the pornographic reduction of women in static representations just when ideas of feminism and gender were starting to develop during that time. Her message is commensurate to a direct, unapologetic, political affront to the abstract objectification of the female body as a fetish. She moved an aesthetic gesture beyond the representational context of the safe boundaries of art into an actual encounter with a public. Export effectively brought to the fore the various dimension of simple, albeit arresting, bodily gestures â€Å"both to produce and to represent action [. . . ] by stressing the moment and the process of its own production† (Stiles, n. d. ). Export repudiated the representational static sign and discharged an interventionist act by revealing her yonic-self to the public vis-a-vis the photos on the display. Art performance, in the recent decades since its entrance in the mainstream, has, and is continuing to encompass a wide field of human proclivities which spans across a whole, comprehensive range of emotions, symbols and design. Although traditional views on aesthetics and taste still influence much of the productions in the art, more and more innovative, socially-informed, stunningly beautiful works of art performance are being (re-)invented and (re-)discovered every time. It doesn’t matter whether these newly created art forms subscribe to tradition or to the taste of the general public. What matters most is the never-ending quest to plumb the full extent of our humanity as individuals and as a community. Art performance is yet to supplant, at least equal the popularity of video-films, cinema, photography and painting in terms of the instances that these are demanded by the public. But with the works of Marina Abramovic, Ulay, Damien Hirst, Valie Export et al and their boundless passion to break the mold and stun the public to enlightenment, art performance can be considered as a significant cornucopia of art studies and of artistic expression. A number of critics do give favorable comments to Marina Abramovic’s performances and ingenuity, Valie Export’s live photography sessions, Hirst’s â€Å"gleaming vitrines with suspended animals inside† (Freeland, 2001). However, it must be noted that even if the critics find them beautiful and artful still its startling content warrants full attention; nothing short of shallow and pedantic in all respects of praise and criticism. Freeland writes, perhaps disinterestedness has some small and specific role in approaching difficult art by enabling us to try harder to look at and understand something that seems very repugnant to the senses (2001). The work’s content and the artist performing are just as crucial as the theories that surround art performance. It is not so much as merely an arbitrary act done through the caprice of a strange art performer. It is instead, a manifestation of our natural tendencies, our history, our sense of taste and what is beautiful, our entire spirituality and lastly, our consciousness set against the body as a tool to perceive reality. Art performance as practiced by these artists is a celebration of the body and of our community. An excellent performance and performer do more than take the audience to elevated heights, but also give them a sense of being truly and undeniably alive. And such, makes all the difference. References Abramovic, M. (2005). Marina Abramovic: the biography of biographies. New York London: Charta Publishers. Abramovic, M. (1998). Artist body: performances 1969-1998. New York London: Charta Publishers. Freeland, C. (2001). But is it art? : blood and beauty. New York: Oxford University Press, Inc. Mueller, R. (1994). Valie Export: fragments of imagination. Bloomington and Indianapolis: Indiana University Press. Stiles, C. (n. d. ). Aktionshose: genitalpanik (action pants: genital in panic). Retrieved January 15 2008, The Galleries at Moore database. Tang, A. (2005). Gazing at horror: body performance in the wake of mass social trauma. (Masters of Arts program, Rhodes University 2005). .

A Review Of Absorption Refrigeration Technologies Engineering Essay

A Review Of Absorption Refrigeration Technologies Engineering Essay Most of industrial processes use a lot of thermal energy by burning fossil fuels to produce steam or heat for various needs in the industry. After the processes, heat is rejected to the surrounding as waste. This waste heat can be converted to useful refrigeration by using a heat operated refrigeration system, such as an absorption refrigeration cycle. Electricity purchased from utility companies for conventional vapor compression refrigerators can be reduced and cuts down the need for expensive electricity from the central grid. The use of heat operated refrigeration systems help reduce problems related to global environmental, such as the greenhouse effect from CO2 emission from the combustion of fossil fuels in utility power plants. Another difference between absorption systems and conventional vapor compression systems is the working fluid used. Most vapor compression systems commonly use chlorofluorocarbon refrigerants (CFCs), because of their thermo-physical properties. It is t hrough the restricted use of CFCs, due to depletion of the ozone layer that will make absorption systems more prominent. However, although absorption systems seem to provide many advantages, vapor compression systems still dominate all market sectors. In order to promote the use of absorption systems, further development is required to improve their performance and reduce cost. The early development of an absorption cycle dates back to the 1700s. It was known that ice could be produced by an evaporation of pure water from a vessel contained within an evacuated container in the presence of sulfuric acid. In 1810, ice could be made from water in a vessel, which was connected to another vessel containing sulfuric acid. As the acid absorbed water vapor, causing a reduction of temperature, layers of ice were formed on the water surface. The major problems of this system were corrosion and leakage of air into the vacuum vessel. In 1859, Ferdinand Carre introduced a novel machine using wat er/ammonia as the working fluid. This machine took out a US patent in 1860. Machines based on this patent were used to make ice and store food. It was used as a basic design in the early age of refrigeration development. In the 1950s, a system using lithium bromide/water as the working fluid was introduced for industrial applications. A few years later, a double-effect absorption system was introduced and has been used as an industrial standard for a high performance heat-operated refrigeration cycle. However with the advent of cheaper vapor compression machines in the late 1960s and abundant and widespread availability of electricity lead to the vapor absorption machines taking a backseat. As a result we see that despite the fact that this technology has been around for almost 250 years, a viable alternative to the vapor compression machines for domestic use at a comparable cost has not been found. The aim of this paper is to provide basic background and review existing literature on absorption refrigeration technologies. A number of absorption refrigeration systems and research options are provided and discussed. It is hoped that, this paper should be useful for any newcomer in this field of refrigeration technology and generate in this area the same interest that the authors feel. PRINCIPLE OF OPERATION The absorption refrigeration system works with a binary solution consisting of refrigerant and absorbent. In Fig. 1(a)[1] two evacuated containers are connected to each other. The container on the left has liquid refrigerant while the right container has a binary solution of absorbent/refrigerant. The solution in the right container will absorb refrigerant vapor from the left one causing pressure to reduce. While the refrigerant vapor is being absorbed, the temperature of the remaining refrigerant will reduce as a result of its vaporization. This causes a refrigeration effect to occur inside the left container thus dropping its temperature. At the same time, solution inside the right container becomes weaker in concentration because of the higher content of refrigerant absorbed. This is due to the absorption process. Absorption process is an exothermic process; therefore, it must reject heat out to the surrounding in order to maintain its absorption capability. Whenever the solution cannot continue with the absorption process because of saturation of the refrigerant, the refrigerant must be separated out from the diluted solution.[1] Heat is usually the key for this separation process. The separation of the refrigerant is of paramount significance and most of the work recently has gone into making this as efficient as possible so as to increase the refrigeration effect. It is applied to the right container in order to dry the refrigerant from the solution as shown in Fig. 1(b).[1] The refrigerant vapor will be condensed by transferring heat to the surroundings. With these processes, the refrigeration effect can be produced by using heat energy. However, the cooling effect cannot be produced continuously as the process cannot be done simultaneously. Therefore, an absorption refrigeration cycle is a combination Fig. 1. (a) Absorption process occurs in right container causing cooling effect in the other; (b) Refrigerant separation process occurs in the right container as a result of additional heat from outside heat source. of these two processes as shown in Fig. 2.[1] As the separation process occurs at a higher pressure than the absorption process, a circulation pump is required to circulate the solution. Coefficient of Performance of an absorption refrigeration system is obtained from The work input for the pump is negligible relative to the heat input at the generator; therefore, the pump work is often neglected for the purposes of analysis. Fig. 2. A continuous absorption refrigeration cycle composes of two processes mentioned in the earlier figure. WORKING FLUID PAIRS FOR ABSOPRTION SYSTEMS The performance of an absorption system is heavily dependent on the properties of the working pair. We are mainly concerned with the thermal and chemical properties of the working fluids. The fundamental requirement is the absorbent/refrigerant combination, in liquid phase, must have a margin of miscibility in the operating temperature range of the cycle. The mixture should also be chemically stable, non toxic, non corrosive and should be able to maintain its fluidity in the operating range. Apart from these certain other desirable properties are: The difference in the boiling points of the pure refrigerant and mixture at the same pressure must be as large as possible. Refrigerant should have high heat of vaporization and high concentration within the absorbent in order to maintain low circulation rate between the generator and the absorber per unit of cooling capacity. Transport properties that influence heat and mass transfer, e.g., viscosity, thermal conductivity, and diffusion coefficient should be favorable. Both refrigerant and absorbent should be environmental friendly and low-cost, specially keeping in mind the increasing danger to the environment. The absorption refrigeration system, which has some advantages, such as silent operation, high reliability, long service life, simpler capacity control mechanism, easier implementation, and low maintenance, is widely acknowledged as a prospective candidate for efficient and economic use of solar energy for cooling applications. Also, the absorption refrigeration cycle is usually a preferable alternative, since it uses the thermal energy collected from the sun without the need to convert this energy into mechanical energy as required by the vapor compression cycle. In addition, the absorption cycle uses thermal energy at a lower temperature than that dictated by the vapor compression cycle. Many working fluids are suggested in literature. A survey of absorption fluids provided by Marcriss [2] suggests that, there are some 40 refrigerant compounds and 200 absorbent compounds available. However, the most common working fluids are NH3- H2O and LiBr-H2O. The binary systems of NH3- H2O and LiBr-H2O are well known as working fluid pairs to be used both in absorption heat pumps and in absorption refrigerators at present. Theoretical and experimental studies have been conducted to optimize the performance of absorption refrigeration cycles using NH3- H2O and LiBr-H2O as refrigerant- absorbent combination. The advantage for refrigerant NH3 is that it can evaporate at lower temperatures (i.e. from -10 to 0 °C) compared to H2O (i.e. from 4 to 10 °C), therefore, for refrigeration, the NH3-H2O cycle is used. NH3 has a high latent heat of vaporization, which is necessary for efficient performance of the system. It can be used for low temperature applications, as the freezing point of NH3 is -77 °C. Since both NH3 and water are volatility, the cycle requires a rectifier to strip away water that normally evaporates with NH3. Without a rectifier, the water would accumulate in the evaporator and offset the system performance. There are other disadvantages such as its high pressure, toxicity, and corrosive action to copper and copper alloy. However, water/NH3 is environmental friendly and low-cost. The use of LiBr-H2O for absorption refrigeration systems began around 1930. Two outstanding features of LiBr-H2O are non-volatility absorbent of LiBr (the need of a rectifier is eliminated) and extremely high heat of vaporization of water (refrigerant). However, using water as a refrigerant limits the low temperature application to that above 0 °C. As water is the refrigerant, the system must be operated under vacuum conditions. At high concentrations, the solution is prone to crystallization. It is also corrosive to some metal and expensive. Research has been performed for NH3-H2O systems theoretically and experimentally and these studies show that the NH3-H2O system exhibits a relatively low COP when compared to its LiBr-H20 counterpart.[1] Efforts are being made to search for better working fluid pairs that can improve system performance. It is proposed that NH3-LiNO3 and NH3-NaSCN cycles can be alternatives to NH3-H2O systems.[3] A study on the use of NH3-LiNO3 and NH3-NaSCN cycles by Jasim M. Abdulateef [3] reveals that ammonia-lithium nitrate and ammonia-sodium thiocyanate cycles give better performance than the ammonia-water cycle, not only because of higher COP values, but also because of no requirement for analyzers and rectifiers. Therefore, they are suitable alternatives to the ammonia-water cycle. Generally speaking, the performance for the ammonia-lithium nitrate and ammonia-sodium thiocyanate cycles are similar, with the latter being slightly better than the former. However, the ammonia-sodium thiocyanate cycle cannot operate at evaporator temperatures below 10 °C for the possibility of crystallization.[3] LITHIUM BROMIDE-WATER ABSORPTION SYSTEM There has been renewed interest to use thermally driven cooling systems from the air conditioning and process cooling fraternities. The lithium bromide-water absorption chiller is one of the front-runners due to the following reasons [4]: It can be thermally driven by gas, solar energy, and geothermal energy as well as waste heat, which help to substantially reduce carbon dioxide emission, this is its USP when it comes to process industries generating large amount of waste heat Its use of water as a refrigerant, which is easily available and cheap. It is quiet, durable and cheap to maintain, being virtually void of high speed moving parts; Its vacuumed operation renders it amenable to scale up applications. LiBr-H2O absorption chillers enjoy cooling capacities ranging from kilowatts (kW) to megawatts (mW) which match with small residential to large scale commercial or even industrial cooling needs. However they currently enjoy only a fraction of the extent of deployment as their vapor compression counterparts. Their major debilitating factors are a low Coefficient of Performance (COP), larger footprint and required headroom, corrosion and crystallization issues and stringent requirements of vacuum leak tightness over its design lifespan. Over the past 30 years, extensive efforts have been devoted to: Develop advanced absorption cycles which could work at low heat source temperature or recover more heat to improve system performance. Improve the design of major components such as generator and absorber to enhance their heat and mass transfer efficacy. Avoid crystallization problem and, Develop new and reliable working pairs. Problems in domestic use of LiBr-H2O absorption systems Even though the technology has been around for quite some time now its usage in domestic applications is hitherto seen. According to Kevin D. Rafferty [5] there is only one company (Yazaki, undated) currently manufacturing small tonnage ( While calculating the mass flow rate of the refrigerant for an assumed case of 1.5TR cooling, as is the requirement for most domestic air-conditioning applications, we obtained a very low mass flow rate in the order of a few gm/s. Also the ensuing pressure difference to maintain such working conditions led to a very high pressure ratio, to the order of about 50, between the absorber and generator. Upon market survey, (here in Pune, India) we discovered that pumps catering to such a low flow rate at this large a pressure differential were not readily available, some suppliers of customized pumps, however, did claim to be able to make such pumps, albeit at a very high cost. We explored the idea of then increasing the mass flow rate to higher than what was calculated for the required tonnage, but realized that increasing mass flow rate for evaporator of same tonnage would lead to un-evaporated refrigerant thus decreasing the COP of the system. During further study of the LiBr-H2O absorption systems we came across an interesting review on absorption chillers and their various configurations by Xiaolin Wang and Hui T. Chua [4], which provides a valuable insight. For the standard single effect system, simple structure and low cost are pursued. The single-effect double-lift absorption system are proposed and developed for the utilization of low temperature heat sources. However, multi-effect absorption systems are suggested to provide higher efficiency with a high temperature heat source. In order to increase the system performance and avoid crystallization problem, various heat and mass recovery systems, modifications to the generator and the absorber, different working pairs and additives have been developed. Furthermore hybridization of absorption chiller cycle with other cooling cycle(s) promises a higher overall performance as compared with that of each single constituent cycle. Single-Effect Absorption Chillers It consists of evaporator, absorber, generator, and a condenser. Its simplicity, small size, high reliability and lower maintenance cost are its advantages. While low cooling capacity, high weight and size and low COP are disadvantages Fig. 3. A schematic of a single effect absorption cycle in a Dà ¼hring plot Uchida from Hitachi developed a modular cascaded absorption chiller comprising of chiller units connected to one another in which chilled water flows through the chiller units in series while cooling water through parallel. [6] Water in chilled and cooling column flows in opposite direction and in absorber solution is sprayed in 1 or more stages. In this type of arrangement lower evaporator temperature can be achieved as compared to conventional arrangement. This results in lower amount of water circulation and higher efficiency due high average temperature difference, compact size, and lower capacity pumps. Inoue from Ebara Corporation integrated the absorber, evaporator, generator, and a condenser into a compact housing so that it can be used for used in residential operations. The arrangement is as shown in Fig. 4. A Absorber, C Condenser, E Evaporator, G Generator, X -Solution heat exchanger, SP Solution pump, RP Refrigerant pump Fig. 4. A single effect absorption chiller [7] This also resulted in reduced costs, compact size, less thermal stresses and low material usage. Inoue from Ebara Corporation in further bid to reduce size and increase COP used plate type heat exchanger in absorber and condenser. [7] In this water flows into the absorber and condenser in parallel and is distributed according to fluid resistance in each unit. This reduces mass flow rate and distributed flow results in elimination of complicated valve system. Problem of crystallization in chiller is avoided using popular J-tube technology. [4] Crystallization in system occurs in generator due to high concentration of LiBr resulting in blockage of flow to solution heat exchanger and will be accumulated in generator. When solution reaches certain level in generator, the hot refrigerant -weak solution will overflow via J-tube to the absorber and warms the refrigerant -strong solution immediately. This will warm the crystallized solution and dissolve them into the solution. Single-Effect Double Lift Absorption Chillers Fig. 5. A single-effect double lift cycle. Since single effect cycle requires the temperature of 90oC and above for proper working, for temperature lower than this results in significant drop in efficiency of the cycle. Therefore utilize to lower temperatures single effect single lift which can work for heat source between 70oC and 90oC and single effect double lift cycle works within waste heat source temperature down to 55oC was developed. A COP in the range of 0.35-0.7 is obtained. [4] Fig. 5. shows the construction of single effect double lift cycle consists of evaporator, absorber-1, generator-1, and a condenser forming single effect cycle the evaporator, absorber-1, generator-3, absorber-2, generator-2, and condenser constitute a double lift cycle. In this the solution from absorber1 is first is sent to generator-1 for steam generation, after this serially solution is sent generator-3 for further generation and refrigerant- weak solution is sent to absorber-1 . The steam generated in generator-3 is absorbed by the absorber-2 which then sent to the generator-2 for generation. The steam from generator-1 and generator-2 is sent in condenser to continue the cycle. The hot water in the system is supplied serially to the generator-1, generator-2, and generator-3. The cooling water flows to the condenser, absorber-1 and absorber-2 in parallel to avoid complicated control and unstable working conditions. The advantage of this system is high COP as compared single effect cycle since energy is utilized more effectively in this cycle. But due increase in number of components this has larger size as compared to single effect cycle. This system is commercialized by INVEN absorption GmbH. [4] Double-Effect Absorption Chillers Fig. 6. A double effect series flow type absorption cycle. This system is developed to increase COP of absorption chiller operating at temperature greater than 150oC since at this temperature the COP of single effect cycle is low. COP achieved in this cycle is in the range of 1.1 to 1.3. It was first patented by Loweth in 1970[8] and commercialized by Trane in the same year. Saito [9] from Ebara Corporation and Alefeld [10] improved and modified the double effect absorption refrigeration machine in 1980 and 1985, respectively. As shown in the plot above, double effect cycle consists of a high temperature and a high pressure generator. Steam generated from this generator is used to generate steam from low pressure generator through a heat exchanger. This steam is further sent to the condenser and evaporator for cooling. This arrangement is known as series flow arrangement. Therefore temperature differential utilization in double effect is more as compared to the single effect but heat rejected at the condenser and cooling temperature at the evaporator are at about the same temperature, hence COP is greater. Above mentioned arrangement works very close to crystallization temperature of LiBr-water solution and the high temperature generator operates at high pressure in order maintain requisite solution flow rate. To avoid solution pumping, the high temperature generator has to be sufficiently elevated to enjoy gravity assisted flow, resulting in higher head room. To avoid these problems, Hitachi developed a parallel flow double effect arrangement as shown below in Fig. 7. In this arrangement solution is separated after solution pump and is sent to high temperature generator through high temperature heat exchanger and to the low temperature generator, respectively. So, the operation condition is displaced further from crystallization point of solution. Flow rate of solution, pressure, elevation is also reduced as compared to series flow arrangement. Nagao from Hitachi disclosed a chiller which consists of an absorption section, an evaporator section, a condenser section, a generator section all of which are divided into two stages. The first stage evaporator second stage evaporator are arranged to be enclosed respectively by first stage absorber second stage absorber. Similar configuration is applied to the generator and condenser. This arrangement reduces heat transfer losses. Fig. 7. A double effect parallel flow type cycle. Hiro [11] from Sanyo Electric Co. disclosed a double effect absorption chiller, in which the connecting pipe conveying the liquefied refrigerant in the low temperature generator to the condenser is installed with an orifice together with a control valve so as to control the refrigerant pressure. A control circuit is connected to this control valve to actively control the refrigerant pressure and therefore control the solution concentration in the high temperature generator and the absorber. This control circuit facilitates the passage of the refrigerant to the condenser without stagnation during chiller start up or in the event of a sudden increase in cooling load. It is also capable of maintaining a suitably reduced pressure in the refrigerant during steady-state operation so as to achieve a higher operating efficiency. Recently Aoyama [12] from Ebara Refrigeration Equipment System disclosed an internal heat recovery scheme which aims to increase intrinsic COP of the machine and heat scavenging scheme which strives to extract more energy from heat source which drives the chiller. According to this invention, the refrigerant rich solution path leading from the absorber to the high temperature generator is divided into two routes. The first route is installed with one or two drain heat exchanger to scavenge the remaining enthalpy of the heat source powering the high temperature generator. The second route is installed with one or two regenerative heat exchanger to recover the heat of the hot and refrigerant-weak solution leaving the high temperature generator. Modeling and Simulation of LiBr-H2O absorption systems A recent paper by V. Mittal, K.S. Kasana and N.S. Thakur on Modeling and simulation of a solar absorption cooling system for India [13] simulated the model of a solar-powered, single stage, absorption cooling system, using a flat plate collector and water-lithium bromide solution. A computer program was developed for the absorption system to simulate various cycle configurations with the help of various weather data for the village Bahal, District Bhiwani, Haryana, India. The effects of hot water inlet temperatures on the coefficient of performance (COP) and the surface area of the absorption cooling component were studied. Simulation results are discussed in this section for the performance of a 10.5 KW solar driven lithium bromide absorption cooling system. Fig. 8. depicts the effect of the hot water inlet temperatures Ts on the system COP and flow ratio FR. It can be seen that an increase in this temperature resulted in the decreases of FR. This is due to increases in the mass fraction of concentration solution (XG). While with an increase in this temperature, COP increases. Fig. 8. The effect of the hot water inlet temperatures on the system COP and FR (Te = 280 K, QL = 10.5 KW, Tc = 306K) Figure 3 depicts the effect of the hot water inlet temperature on the surface area of the system components. It can be seen that increase in this temperature results in the decrease of the absorber and solution heat exchanger surface area. As flow ratio decreases, the thermal energy extracted from the absorber also decreases and hence the temperature of the absorber increases, which further resulted in the increase of logarithmic mean temperature difference (DTm) in the absorber and solution heat exchanger. By decreasing the heat capacity and increasing DTm, heat transfer surface area normally decreases in these components. Fig. 9. The effect of the hot water inlet temperatures on the surface area of the system components (Te = 280 K, QL = 10.5 KW, Tcool, in = 291 K) From this study the following conclusions were made: The hot water inlet temperature is found to affect the surface area of some of the system components. Increasing this temperature decreases the absorber and solution heat exchanger surface area, while the dimensions of the other components remain unchanged. Although high reference temperature increases the system COP and decreases the surface area of system components, lower reference temperature gives better results for FNP than high reference temperatures do. For this study, a 353 K reference temperature is the best choice. This paper thus provides a general idea to anyone looking to build a model of a vapor absorption system, about the generator temperature needed and its effect on the flow rate and COP. AMMONIA-WATER ABSORPTION SYSTEM The working of ammonia-water absorption refrigeration system is based on the  simple vapor absorption refrigeration systems. In this system ammonia is used as the refrigerant and water is used as the absorbent. The ammonia-water absorption system is used in the domestic as well the commercial applications where the requirement of the temperature is below 0 degree C. The major advantages of the ammonia-water solution are: Water has strong affinity for ammonia and they are soluble with each other in wide operating conditions that occur in different refrigeration applications. The ammonia-water solution is highly stable and works well with many materials. Ammonia is a common chemical and it is easily and cheaply available. However the system has a few disadvantages too some of which are: Except copper and its alloys that get corroded in the presence of ammonia. Due to its toxicity its applications are limited. Due to the fact that some of the water in the generator also boils off with the ammonia and escapes as vapor, a rectifier is needed to remove this water vapor before it enters the condenser. This adds to the expense and complexity of the design. The COP of the ammonia-water systems is slightly lower than their LiBr-water counterparts. Fig. 10. Schematic of a typical ammonia-water absorption system. Domestic use of ammonia-water absorption systems Unlike the LiBr-H2O absorption system, the ammonia-water absorption system has found widespread use in the domestic use market. These refrigerators are very popular as car fridges used in SUVs and RVs. Many companies are involved in the manufacturing of such equipment. Electrolux was amongst the first companies to start manufacturing absorption refrigerators for commercial use. One of the main issues with the early domestic absorption refrigerators was that the water would get crystallized and the whole setup would then need to be inverted for a few hours to get the system working again. Such old models of absorption models are available in scrap; however most of them are not in working condition. We came across one such model ourselves, however even on extensive research the exact composition of the water ammonia mixture or the operating pressure was not found. Most people do not recommend recharging of these old units as they are factory sealed and compositions are not known, however some people have tried recharging and obtained successful results. Simulation of absorption diffusion Solar refrigeration systems A study was carried out by B. Chaouachi and S. Gabsi [14] for the design and the simulation of an absorption diffusion refrigerator using solar as source of energy, for domestic use. The design holds account about the climatic conditions and the unit cost due to technical constraints imposed by the technology of the various components of the installation such as the solar generator, the condenser, the absorber and the evaporator. Mass and energy conservation equations were developed for each component of the cycle and solved numerically. The absorption diffusion refrigerating machine is designed according to the operation principle of the refrigerating machine mono pressure invented by Platern and Munter. This machine uses three operation fluids, water (absorbent), ammonia (Refrigerant) and hydrogen as an inert gas used in order to maintain the total pressure constant. The study yielded some interesting conclusions. The operating boundaries of the system were examined by conducting simulations for various values of the generator temperature, TG, the evaporator temperature, TE, the pressure of the system, P and the generator heat input, QG. The operation ranges were found to be: 5 Fig. 11. COP vs. to generator temperature for various pressures of the system (ÃŽÂ ¾r=0.45, Te=273K) Fig. 11. presents the COP vs. the generator temperature for different pressures of the system for a fixed rich concentration and evaporator temperature. It shows that the COP decreases as the generator temperature increases and it increases when the pressure increases too. This is may be attributed to the fact that a smaller amount of ammonia was separated from the ammonia-water solution and thus more solution had to be circulated so as to maintain the refrigerant flow rate in the condenser. It thus recommended that pressure of the system as high as possible. Fig. 12. OP vs. the evaporator temperature (ÃŽÂ ¾r = 0.4, P=12.5 bars) The Fig. 12. shows that the COP decreases as the generator temperature increases. It was also found that the higher the evaporator temperature, the higher COP, i. e. that more heat was absorbed in the evaporator. There are thus opposing demands for the evaporator temperature; on the one hand, it should be high enough (depending on the desired cooling capacity) to yield a higher COP, while a lower evaporator temperature would yield better cooling. Thermodynamic simulation of Solar absorption refrigeration systems Another thermodynamic simulation carried out by Antonio J. Bula [15], for an ammonia water solar absorption system. The operating conditions chosen were: Tg = 70 90 °C Tc = 30  °C Ta = 25  °C Te = 5  °C

The Blank Slate of Frankenstein’s Mind :: Frankenstein Essays Brain Locke Papers

The philosophical root of Frankenstein seems to be the empiricist theory first promoted by John Locke in An Essay Concerning Human Understanding. In that essay, the mind is concieved as beginning as a blank slate or tabula rasa, upon which the various impressions gained by the outside world shape the personality. According to this strict empiricism, the mind contains no innate basis for the basic prerequisites for human socialization: a social code and/or morality with empathetic roots. As a result of the monster's isolation, he is unable to sympathize with human beings and loses respect for other intelligent life. Even though the monster has good intentions, his beneficence is subverted by the negative and anti-social reactions he receives from the people he encounters. The most blatent passages in support of the tabula rasa can be found in the monster's account of the impressions of his early life at the beginning of Chapter IX (pg 70 Dover Edition). The relevant portion starts at the beginning of the chapter, but the passage of most interest is reproduced below: "Several changes of day and night passed, and the orb of night had greatly lessened, when I began to distinguish my sensations from each other. I gradually saw plainly the clear stream that supplied me with drink, and the trees that shaded me with their foliage. I was delighted when I first discovered that a pleasant sound, which often saluted my ears, proceeded from the throats of the little winged animals who had often intercepted the light from my eyes. I began also to observe, with greater accuracy, the forms that surrounded me, and the boundaries of the radient roof of light which canopied me. Sometimes I tried to imitate the pleasant sounds of the birds, but was unable. Sometimes I wished to express my sensations in my own mode, but the uncouth and inarticulate sounds which broke from me frightened me back into silence." While this account is probably a poor model of how an actual entity would behave upon being thrust into a brand new world of sensations with sufficient cognitive apparati to comprehend the impressions (categories and systemization are utilized almost immediately, although there would be no reason for the monster to arrange things in this way, "light from my eyes" is a physical principal [an incorrect one at that] and would not likely be used in a naive description. The Blank Slate of Frankenstein’s Mind :: Frankenstein Essays Brain Locke Papers The philosophical root of Frankenstein seems to be the empiricist theory first promoted by John Locke in An Essay Concerning Human Understanding. In that essay, the mind is concieved as beginning as a blank slate or tabula rasa, upon which the various impressions gained by the outside world shape the personality. According to this strict empiricism, the mind contains no innate basis for the basic prerequisites for human socialization: a social code and/or morality with empathetic roots. As a result of the monster's isolation, he is unable to sympathize with human beings and loses respect for other intelligent life. Even though the monster has good intentions, his beneficence is subverted by the negative and anti-social reactions he receives from the people he encounters. The most blatent passages in support of the tabula rasa can be found in the monster's account of the impressions of his early life at the beginning of Chapter IX (pg 70 Dover Edition). The relevant portion starts at the beginning of the chapter, but the passage of most interest is reproduced below: "Several changes of day and night passed, and the orb of night had greatly lessened, when I began to distinguish my sensations from each other. I gradually saw plainly the clear stream that supplied me with drink, and the trees that shaded me with their foliage. I was delighted when I first discovered that a pleasant sound, which often saluted my ears, proceeded from the throats of the little winged animals who had often intercepted the light from my eyes. I began also to observe, with greater accuracy, the forms that surrounded me, and the boundaries of the radient roof of light which canopied me. Sometimes I tried to imitate the pleasant sounds of the birds, but was unable. Sometimes I wished to express my sensations in my own mode, but the uncouth and inarticulate sounds which broke from me frightened me back into silence." While this account is probably a poor model of how an actual entity would behave upon being thrust into a brand new world of sensations with sufficient cognitive apparati to comprehend the impressions (categories and systemization are utilized almost immediately, although there would be no reason for the monster to arrange things in this way, "light from my eyes" is a physical principal [an incorrect one at that] and would not likely be used in a naive description.

Ozymandius

Commanding poems that continue to be talked about and analyzed to this day. Each sonnet was published by Leigh Hunt early in 1818 in consecutive issues of his monthly Journal, The Examiner (Rumens, 2010). Even though the sonnet written by Smith has taken a back seat to Shelley in scholarly study, both poems explore the opulence of ancient history and the inevitable consequences of time. Inspired by recent discoveries in the Near East, Shelley and Smith were motivated by the words of historian Odorous Sculls who claimed the inscription on the statue of Renames II read, â€Å"King of Kings Commanding am l.If any want to know how great I am and where I lie, let him outdo me in my work† (Mimics, 2010). The motivation for these separatist poems was to create a piece of artwork that would withstand the inevitable passing of time. Unlike the crumbling boasting monuments of Ancient Egypt whose intent was to memorial their rule, their own literary words would be a piece of poetic art t hat would forever be remembered in European literature. While the differences outweigh the similarities between these woo poems, there is a uniting theme expressed by both Shelley and Smith.Each author uses the same subject, tells the same story and makes the same moral point of the arrogance of human authority and the inevitable decline of all leaders. Every great leader wants to be amortized and remembered. Time is the ceaseless enemy of this great wish of mortal men. It never stops, takes pause or shows tire as it breaks down the most triumphant of mortal monuments. Both poems use the expression of time to unite the idea that all power is fleeting as exampled by the only mains of the statue's leg.The variations in diction between Shelley and Smith allows for a vast difference of perspective. Smith, an author of historical novels and financial advisor to Shelley, lacked an overall flare that is seen in Shelley poem. However, his words reinforce the sense of loss and emptiness of t he desert and that forgotten Babylon' (Smith, 1818). Smith chooses a future perspective of someone stopping upon the ruins and wondering what greatness once resided in the Egyptian desert. His words are less imaginative and the tone of the poem comes across more loom than wrathful as compared to Shelley.There is no focus on the arrogance and harsh rule of Commanding. On the other hand, Shelley chooses to present the remains of Commanding from the narrator's perspective. The passage, â€Å"Tell that its sculptor well those passions read†, shows that the unrelenting style of rule, as depicted on the visage, was accurately portrayed to the traveler (Shelley, 1818). Shelley is able to strip focus away from Commanding' own aspiration of being amortized and draw attention to the truth of his unsympathetic reign as depicted wrought the hands of the artisan.Shelley literary style and viewpoint makes clear his disdain for ancient rule and monarchies (Solo Interactive Learning). Shelle y and Smith were both inspired by the political developments of their own day and opinions were heightened by the 1821 acquisition of a statue of Rammers II by the British Museum in London. In their own personal style, each poet conveyed the same paradox: â€Å"Commanding, the self-proclaimed King of Kings, commissioned a statue of himself to guarantee his immortality, but all that's left is a broken statue† (Durbin, 012).

Star Charts and Their Many Uses

Star Charts and Their Many Uses The night sky is a fascinating place to explore. Most backyard skygazers begin by stepping out each night and marveling at whatever appears overhead. In time, however, nearly everybody gets the urge to know about what theyre seeing.  Thats where sky charts come in handy.l Theyre like navigational charts, but for exploring the sky. They help observers identify stars and planets in their local skies. A  star chart  or a  stargazing app is one of the most important tools a skygazer can use.  They form the backbone of specialized astronomy apps, desktop programs, and are found in many astronomy books.   Charting the  Sky To get started with star charts, search out a location on  this handy Your sky page. It  lets observers select their location and get a real-time sky chart. The page can create charts for areas around the world, so its also useful for people planning trips who need to know what the skies will contain at their destination. For example, lets say someone lives in or near Fort Lauderdale, Florida. They would scroll down to Fort Lauderdale on the list​ and click on it. It will automatically calculate the sky using the latitude and longitude of Fort Lauderdale as well as its time zone. Then, a sky chart will appear. If the background color is blue, it means the chart is showing the daytime sky.  If its a dark background, then the chart shows the night sky.   The beauty of these charts is that a user can click on any object or area in the chart to get a telescope view, a magnified view of that region. It should show any objects that are in that part of the sky. Labels such as NGC XXXX (where XXXX is a number) or Mx where x is also a number indicate deep-sky objects. Theyre probably galaxies or nebulae or star clusters. M numbers are part of Charles Messiers listing of faint fuzzy objects in the sky, and are worth checking out with a telescope. NGC objects are often galaxies. They may be accessible through a telescope, although many are fairly faint and hard to spot. Astronomers over the ages have collaborated on and created different lists of sky objects. The NGC and Messier lists are the best examples and are the most accessible to casual stargazers as well as advanced amateurs. Unless a stargazer is well-equipped to search out faint, dim, and distant objects, the advanced lists really arent of too much importance to backyard-type skygazers. Its best to stick with the really obvious bright objects for good stargazing results.Some of the better stargazing apps also allow a user to connect to a computerized telescope. The user inputs a target and the charting software directs the telescope to focus on the object. Some users then go on to photograph the object (if theyre so equipped), or simply gaze at it through the eyepiece. There is no limit to what a star chart can help an observer do.   The Ever-Changing Sky Its important to remember that the sky does change night after night. Its a slow change, but eventually, dedicated observers will notice that whats overhead in January is not visible in May or June. Constellations and stars that are high in the sky in the summertime are gone by mid-winter.  This happens throughout the year. Also, the sky seen from the northern hemisphere is not necessarily the same as what is seen from the southern hemisphere. There is some overlap, of course, but in general, stars and constellations visible from the northern parts of the planet arent always going to be seen in the south, and vice-versa.The planets slowly move across the sky as they trace their orbits around the Sun. The more distant planets, such as Jupiter and Saturn, stay around the same spot in the sky for a long time. The closer planets such as Venus, Mercury, and Mars, appear to move more quickly.   Star Charts and Learning the Sky A good star chart shows not only the brightest stars visible at a given location and time but also gives constellation names and will often contain some easy-to-find deep-sky objects. These are usually such things as the Orion Nebula, the Pleiades star cluster, the Milky Way galaxy that we see from inside, star clusters, and the nearby Andromeda Galaxy. Learning to read a chart enables skygazers to know exactly what theyre looking at, and leads them to explore for more celestial goodies.  Ã‚   Edited and updated by Carolyn Collins Petersen.

Word Choice Cord vs. Chord - Proofeds Writing Tips Blog

Word Choice Cord vs. Chord Word Choice: Cord vs. Chord Homonyms are words that sound identical but differ in meaning. As you might have already found, these tricky terms can be problematic. Fear not, though! Proofed is here to guide you through your vocabulary-based crises. Today in our ongoing Word Choice series, we tackle â€Å"cord† and â€Å"chord,† which are confusingly similar even before you get into their tangled etymologies (which, for the sake of simplicity, we’ll ignore). Cord (A String or Rope) The noun â€Å"cord† can mean a number of things, but the most common uses are to mean â€Å"a length of rope† or â€Å"an electrical cable.† Specifically, the term â€Å"cord† is used when describing flexible material thicker than a string but thinner than a rope, or the insulated wire connecting an electrical device to power source: After wrestling Jeremy to the ground, Matilda hogtied him with a length of cord. It was an hour before Boris realized his computer was missing its power cord. Another common context in which the word â€Å"cord† appears is medicine, where it applies to certain anatomical structures (e.g., â€Å"umbilical cord,† â€Å"vocal cords†). There are a few additional definitions too, such as a measurement for cut wood or the raised ribs on corduroy pants; these latter meanings are quite specialized though, so you probably don’t need to memorize them. Chord (A Pleasing Musical Arrangement) The word â€Å"chord† is a noun describing â€Å"three or more musical tones being played simultaneously.† On guitar, for example, the chord C is composed of the notes C, E and G. As such, â€Å"chord† is usually found in musical contexts: As soon as I heard the opening chords of â€Å"Born to Run,† I was an instant Springsteen fan. Sometimes â€Å"chord† is also used metaphorically, such as when we say something â€Å"struck a chord† with someone, which means to have made an emotional impact or evoke a reaction: Harriet didn’t care for politics, but the senators speech said had struck a chord with the whole crowd. Cord or Chord? Once you know what these words mean, it’s fairly easy to know which to use in any given situation. Simply ask yourself the following question: Are you describing a length of flexible material or an electrical wire? Or an anatomical structure? If so, use â€Å"cord.† Are you describing something musical? Or using the idiom â€Å"strike a chord†? If so, the term you’ll want is â€Å"chord.† Keep these guidelines in mind to avoid mixing them up in your written work. And to make doubly sure your papers are free from this kind of mistake, you can’t beat the expert eyes of a professional proofreader.

Proofreading Marks 101 What Do These Squiggles Mean

Proofreading Marks 101 What Do These Squiggles Mean What Are the Meaning of Proofreading Marks? Having your work come back from an editor covered in red pen is daunting to begin with. Receiving a manuscript that's covered in proofreading marks that might as well be hieroglyphics can be even more intimidating.But before you reach for your cipher wheel, remember that the purpose of proofreading marks isn’t to confuse you. It’s to provide a detailed roadmap to a professional and polished final manuscript. While independent authors are not likely to spring for large print runs which would be ruined by more than a couple of typoe - proofreading still remains an essential step for most serious self-publishers. What are the meaning of proofreading marks? Find out here! #amediting These days, it’s unlikely for the proofreading process to take place via pen-and-paper, meaning that the use of proofreading marks is also becoming increasingly rare. Most proofreaders used tools such a â€Å"tracked changes† to flag issues - and many indie authors choose to forgo professional proofers for software such as Grammarly or the simple red, dotted line that signifies a typo in processors such as Microsoft Word or Google Docs.That being said, screen fatigue is a real thing and there’s something about a hard-copy document that seems to draw the eye to errors more than a digital one. So if you’re working with a proofreader and want to ensure the collaboration fulfills its top potential, it’s worth getting to know the meaning of the more common proofreading marks.So, without further ado†¦ Once you’ve done all the proofreading work you can, we encourage you to consider working with a professional. Proofreading is the final stage of the editing process and will ensure your book fully meets its potential for success.The average costs of working with a professional proofreader on Reedsy are:$350 for a 40k-word book$520 for a 60k-word book$700 for an 80k-word bookHead to our marketplace to request quotes from a variety of professional proofreaders for free.Have you ever worked with a professional proofreader? Or do you prefer to go the DIY route? Leave any thoughts or questions in the comments below!

Effective Public Administrative System Essay Example | Topics and Well Written Essays - 750 words

Effective Public Administrative System - Essay Example Organizations must ensure that their employees follow the required procedures while handling their daily duties so that negative impacts are experienced and the organization achieves its desired outcomes. The technological advancement pressures the need for expertise in every field of production, improved living conditions, and an informed decision-making. An organization for example oil-producing company must have and implement strict policies governing its operations, occupational health, and compliance to the state laws governing processing and manufacturing industries (United Nations, 2005). The state requires that such companies must conduct environmental impact assessment so that they do not cause more harm to the environment and the people living within the vicinity of the industry. The state has in place the regulations and standards a company must meet before carrying out its operations, which the management of the organization must ensure that it complies and meets them, fa ilure to which permit is denied (United Nations, 2005). Oil producing companies require employees with technical expertise in the field of engineering to undertake most of its operations. The recruiting team of the company must ensure that they follow proper ways of employing, so that they do not end up messing with their operations, which consequences are faced by the society. The required knowledge and experience as per the law must be met; employing a software engineer to undertake, direct and supervise oil mining is not practical. The United Nations (2005) indicated that administrative staff of a company must ensure that their employees undergo appropriate induction training relevant to their area of specialization before they start working independently. Laxity in development and implementation of such policies might cause mishandling materials and machines resulting into an explosion causing injuries and deaths. Health facilities are very sensitive area that requires its emplo yees, nurses and doctors, to be qualified and certified by the board. A pharmacist cannot even at one point undertake surgery. It will be going against human right and is unethical as per the work norms and regulations of the country. Deaths will be caused; therefore, the government must ensure that people who are not trained and certified should by the authorizing body do not operate a medical facility, as that is breach of law which the individual must be punished for. Nurses who serve patients impolitely do not deserve to do the jobm because the patients might get traumatized due to stress. The impact caused could have been prevented if there were strict policies and regulations (United Nations, 2005). According to United Nations (2005), corruption is a barrier towards attainment of strong and effective administration of public policies. When politics is allowed to influence the functioning of an organization, for instance, when somebody presents his or her candidate for a certai n position, the independence of the organization no longer exists. The judicial system must be independent and reforms have to be made after a period, so that weaker laws are strengthened. Relying with the old system poses more problems than good to the society. Adoption of new technology improves the performance and operations of an organization. Acquisition of equipment that detects danger and alerts the employees reduces the number of risks

Dejouanys Strategy over CGE Essay Example | Topics and Well Written Essays - 1000 words - 1

Dejouanys Strategy over CGE - Essay Example Dejouany’s management style was not so highly decentralized that it allowed decision making at lower levels. Rather it follows the multidivisional structure, where the division of labor is created between the top managers and division managers, such that it is the division managers who focus on the operational details of the functional departments, while the top managers are able to concentrate on strategic decisions and long-range planning.(Vivendi).Dejouany selected quality people who were well versed in the developing opportunities in a particular area of business, investing cash into those cash-strapped businesses in order that the Company could benefit overall from the potentials inherent in those markets. Â  In pursuing his goals of diversification of CGE from a primarily water-based business into a diversified entity which dealt with real estate and health care among other businesses, Dejouany followed the internal capital market model of diversification. The diversification of CGI was undertaken in order to make use of the internal capital market. Since CGE was a cash-rich business, with vast cash resources accruing from its monopoly in the water business, it was able to enter into the various type of agreements with cash-strapped businesses for mutual benefit. One kind of agreement the Company entered into were agreements where it did not have to invest cash but merely managed the assets of municipalities’ water supplies.

Zionism in the Middle East Essay Example | Topics and Well Written Essays - 2250 words

Zionism in the Middle East - Essay Example The essay "Zionism in the Middle East" describes the basis of the political movement Zionism and the position of this movement in today world. Zionism started as a nationalist movement supporting the re-establishment of Jews and is often perceived as an activity dominated by violence. The movement gained acceleration especially after the break-up of the Ottoman Empire and the British Balfour Declaration, which guaranteed a homeland for the Jews in exchange for certain services to the British Empire. The proposed Jewish homeland was authorized and created after the end of World War II, with a precondition that it would not be created at the expense of the majority Arab population of Palestine. The subsequent policies adopted by the United Nations have been severely criticized for its anti-humanistic treatment of the Palestinian Arabs, the large-scale destruction of their houses and property, and several other incidents that clearly violated and disregarded the international law. Post the infamous holocaust, at the hands of the Nazis, the Jews gained widespread support and sympathy and were then forced to flee their homes in Eastern Europe to settle in Palestine, where they remained a minority community. Alarmed by such large-scale influx of foreign residents, the Palestinian Arabs showed resistance in lending their support to these refugees. Soon they were overcome by the power of the Zionist armed forces, which used their powers and arms to â€Å"cleanse† the land of Arabs and create a homeland for themselves.

The theory of supply and demand Essay Example | Topics and Well Written Essays - 750 words

The theory of supply and demand - Essay Example The theory of supply and demand Supply and demand are two of the most critical concepts in the study of economics, especially in microeconomics where it determines market prices. The law of supply and demand concludes that in the event of an increase in demand while supply stays unchanged, then a shortage will ensue resulting in a higher equilibrium price. On the other hand, the law argues that if demand decreases while supply stays unchanged, a surplus will occur, causing the equilibrium price to fall. However, if demand stays unchanged and supply increases, a surplus will ensue, causing a lower equilibrium price. The last law of supply and demand concludes that if demand remains the same and supply reduces, a shortage will be experienced within the market, resulting in a greater equilibrium price. The earliest records of considerations of the concepts of supply and demand started in the 14th century. 14th century Muslim, Mamluk scholar, Ibn Taymiyyah suggested that if the need for goods within the market increase s while its availability reduces the price of the goods will increase. He also suggested that if the availability of the commodity increases and the need for it diminishes, its prices will come down. . In 1691, John Locke’s work â€Å"Some Considerations on the Consequences of the Lowering of Interest and the Raising of the Value of Money† consists of an early and succinct description of supply and demand, as well as their inherent relationship.... cs subsequently used the term in his 1776 book in which he presumed that the supply price was inflexible, but its value would eventually diminish as its scarcity increased (Krugman and Wells 89). In effect, Smith was speaking to the law of demand. In his work, Principles of Political Economy and Taxation, Ricardo rigorously laid down the notion of the assumptions, which were utilized in order to develop his ideas of supply and demand. In the 19th century, the marginalist school of thought was established, and its key idea was that prices are determined by the most expensive price or the price at the margin. This was a massive change from Smith’s thoughts concerning the determination of supply price through the forces of demand and supply. The model of supply and demand encompasses the supply and demand schedules. A supply schedule is a table, which quantifies the relationship between the price of a product and the quantity supplied. A supply curve shows the link between the pr ice of the product and quantity supplied. Through the assumption of perfect competition, marginal costs determine supply. This means that firms will produce additional products when the production cost of an extra output is less than the price expected. Inherently, supply is determined by production costs, the number of suppliers within the market and the firm’s expectations regarding future prices (Krugman and Wells 247). On the other hand, a demand curve is the graphical depiction of a demand agenda and represents the quantity of goods buyers are both capable and willing to buy at certain prices. The law of demand requires that the demand curve must always be represented as downward-sloping, which means that consumers will by extra goods as prices diminish. Demand curves are also determined

Neuropsychological Patterns of Learning Essay Example | Topics and Well Written Essays - 1250 words

Neuropsychological Patterns of Learning - Essay Example Learning disabilities have remained uniquely linked to individual theoretical models. The methodology of assessing learning disabilities utilizes several factors in explanatory models and various levels of analysis. The objective of this analysis is to review the patterns of variations in learning for children with learning disabilities. The purpose for this analysis is to provide a scholarly critique regarding the patterns of learning of children with disabilities. According to a research conducted by Robert-Jay Green (1990, p. 145), he formulated two hypotheses in investigating the impact of family interaction and structure on information processing deficits of children with learning disabilities. The first hypothesis by Green seeks to research into the relationship between thought orders of schizophrenic children and parental communication. The study employed the use of a scoring manual designed to measure nonconformity in communication. The study highlighted the parent’s i nterpersonal linguistic skills in categorizing, naming, directing shared attention, and explaining world concepts to the children of different age groups and different chores. Green, however, indicates that family communication would have minimal effect on the long run on the child. Further, an environment based on uneven and unstructured communication styles would experience persistent cognitive disorientation and confusion. Hence, this leads to the impairment of a child’s ability to process and keep new information at school. The findings proposed a strong and reliable relationship between deviations in parental communication and diagnosis of schizophrenic and marginal conditions of children. This relationship would be associated to families with cognitively confused schizophrenic children. The analysis revealed a high rate of communication deviance for 87% of parents with children of learning disabilities (Green, 1990, p. 145). The second hypothesis focused on how an under organized family structure would enhance or maintain the attention deficits of children with learning disabilities. It utilized the method of interviewing families of children with learning disabilities and rating them. These children also labeled as Attention Deficit Hyperactivity Disorder or Conduct Disorder displayed an inability to maintain a focused attention. Clinical research indicated that certain features of families hinder a systematic flow of ideas in communication. For instance, erratic and unfocused parental control styles, abrupt topic changes, conflict resolution through threats, deficient communication in words and reasoning, and disciplinary based on moods. These families would be considered chaotic, under organized and detached. Thus, the two hypotheses established an association between family characteristics and children with learning disabilities (Green, 1990, p. 146). However, these two studies failed to establish the direction of impacts between parent and ch ild characteristics, and the role of environment and heredity in the emergence of these family patterns. Hence, the findings do not provide any results on the four etiological models; the genetic, environmental, ecosystem and stress models. Their research assumes that each model would fit only certain subtypes of learning disabilities. It would be recommended that further large-scale longitudinal research be conducted on parents diagnosed as learning disabled

Ethics and Communications in Organizations Essay

Ethics and Communications in Organizations - Essay Example Thus, ethics maintain great significance in everyday human life, where their importance multiplies within the organizational behavior during the course of offering one’s services in one way or the other. Professional ethics also suggest the personnel in respect of developing pleasant and amicable relationships with the management, colleagues, subordinates, clients and the general public at large, through an adequate communication system, which is vehemently important for climbing the ladder of success and growth in one’s career for the future years to come. The contemporary era has made imperative alterations in all fields of human life. The world’s turning into a global village has established such type of business environment, where the individuals belonging to divergent ethnic, racial, regional, religious and family backgrounds as well as obtaining variant educational qualifications, occupational skills, different socioeconomic positions and divergent sexual o rientations work under one roof and under the command of one single administration, during which they have to come across several awkward and unpleasant incidents because of the behaviors of others. Somehow, commitment to one’s cause and dedication to one’s responsibilities serve as the core concepts of climbing the ladder of professional growth and financial stability. It is not specific to one occupation only; rather, the same is applied to all the existing professions of contemporary times at large. â€Å"Values and ethics are central to any organization; those operating in the national security arena are no exception. Both are extremely broad terms, and we need to focus in on the aspects most relevant for strategic leaders and decision makers.† (National Defense University) Ethics in Organizations: One of the most formidable ethics the professionals must apply is their sense of responsibilities towards the workplace. A professional is the representative of h is organization, which offers him job opportunity, respectable place, and financial compensation, along with protecting him from becoming the prey to unemployment, idleness and mental disturbance created because of joblessness. It is, therefore, the professional must render his services to the organization diligently and actively without displaying any reluctance and non-compliance with the duties and obligations he has been hired to accomplish. Additionally, it is also the ethical responsibility of the professional not to let the name, fame, and reputation of his organization go to the dashes, because of his misbehave or negligence towards the customers and clients. Moreover, the professional must check the working of his colleagues, co-workers, and subordinates in order to assure their performance for the best interest of the organization. The professional must also interact with the superiors time and again, and if they are in need of his support at any matter, he must accomplish the same within the appropriate time and without any deliberate delays.  

The theory of supply and demand Essay Example | Topics and Well Written Essays - 750 words

The theory of supply and demand - Essay Example The theory of supply and demand Supply and demand are two of the most critical concepts in the study of economics, especially in microeconomics where it determines market prices. The law of supply and demand concludes that in the event of an increase in demand while supply stays unchanged, then a shortage will ensue resulting in a higher equilibrium price. On the other hand, the law argues that if demand decreases while supply stays unchanged, a surplus will occur, causing the equilibrium price to fall. However, if demand stays unchanged and supply increases, a surplus will ensue, causing a lower equilibrium price. The last law of supply and demand concludes that if demand remains the same and supply reduces, a shortage will be experienced within the market, resulting in a greater equilibrium price. The earliest records of considerations of the concepts of supply and demand started in the 14th century. 14th century Muslim, Mamluk scholar, Ibn Taymiyyah suggested that if the need for goods within the market increase s while its availability reduces the price of the goods will increase. He also suggested that if the availability of the commodity increases and the need for it diminishes, its prices will come down. . In 1691, John Locke’s work â€Å"Some Considerations on the Consequences of the Lowering of Interest and the Raising of the Value of Money† consists of an early and succinct description of supply and demand, as well as their inherent relationship.... cs subsequently used the term in his 1776 book in which he presumed that the supply price was inflexible, but its value would eventually diminish as its scarcity increased (Krugman and Wells 89). In effect, Smith was speaking to the law of demand. In his work, Principles of Political Economy and Taxation, Ricardo rigorously laid down the notion of the assumptions, which were utilized in order to develop his ideas of supply and demand. In the 19th century, the marginalist school of thought was established, and its key idea was that prices are determined by the most expensive price or the price at the margin. This was a massive change from Smith’s thoughts concerning the determination of supply price through the forces of demand and supply. The model of supply and demand encompasses the supply and demand schedules. A supply schedule is a table, which quantifies the relationship between the price of a product and the quantity supplied. A supply curve shows the link between the pr ice of the product and quantity supplied. Through the assumption of perfect competition, marginal costs determine supply. This means that firms will produce additional products when the production cost of an extra output is less than the price expected. Inherently, supply is determined by production costs, the number of suppliers within the market and the firm’s expectations regarding future prices (Krugman and Wells 247). On the other hand, a demand curve is the graphical depiction of a demand agenda and represents the quantity of goods buyers are both capable and willing to buy at certain prices. The law of demand requires that the demand curve must always be represented as downward-sloping, which means that consumers will by extra goods as prices diminish. Demand curves are also determined

Ethics and Communications in Organizations Essay

Ethics and Communications in Organizations - Essay Example Thus, ethics maintain great significance in everyday human life, where their importance multiplies within the organizational behavior during the course of offering one’s services in one way or the other. Professional ethics also suggest the personnel in respect of developing pleasant and amicable relationships with the management, colleagues, subordinates, clients and the general public at large, through an adequate communication system, which is vehemently important for climbing the ladder of success and growth in one’s career for the future years to come. The contemporary era has made imperative alterations in all fields of human life. The world’s turning into a global village has established such type of business environment, where the individuals belonging to divergent ethnic, racial, regional, religious and family backgrounds as well as obtaining variant educational qualifications, occupational skills, different socioeconomic positions and divergent sexual o rientations work under one roof and under the command of one single administration, during which they have to come across several awkward and unpleasant incidents because of the behaviors of others. Somehow, commitment to one’s cause and dedication to one’s responsibilities serve as the core concepts of climbing the ladder of professional growth and financial stability. It is not specific to one occupation only; rather, the same is applied to all the existing professions of contemporary times at large. â€Å"Values and ethics are central to any organization; those operating in the national security arena are no exception. Both are extremely broad terms, and we need to focus in on the aspects most relevant for strategic leaders and decision makers.† (National Defense University) Ethics in Organizations: One of the most formidable ethics the professionals must apply is their sense of responsibilities towards the workplace. A professional is the representative of h is organization, which offers him job opportunity, respectable place, and financial compensation, along with protecting him from becoming the prey to unemployment, idleness and mental disturbance created because of joblessness. It is, therefore, the professional must render his services to the organization diligently and actively without displaying any reluctance and non-compliance with the duties and obligations he has been hired to accomplish. Additionally, it is also the ethical responsibility of the professional not to let the name, fame, and reputation of his organization go to the dashes, because of his misbehave or negligence towards the customers and clients. Moreover, the professional must check the working of his colleagues, co-workers, and subordinates in order to assure their performance for the best interest of the organization. The professional must also interact with the superiors time and again, and if they are in need of his support at any matter, he must accomplish the same within the appropriate time and without any deliberate delays.  

Anatomy and Physiology Ch. 1 Study Guide Essay Example for Free

Anatomy and Physiology Ch. 1 Study Guide Essay Anatomy the study of the form or structure and arrangement of body parts and their relationships Physiology the study of the functions of the body parts or structures and their relationships in maintaining life processes. Levels of Structural Organization The human body consists of levels of structural organization that are associated with one another. There are six levels of structural organization: I. chemical level It is the simplest level and it includes all of the chemical substances essential for maintaining life. These substances are made up of atoms. An atom is the smallest unit of matter. Matter is anything that takes up space and has mass.  Atoms combine to form molecules, which may be simple or  complex. Different types of molecules combine to form or~anelles (little organs). Organelles are specific structures that carry out specific functions. 2. cellular level The cell is the basic unit of structure  and function and of life. Cells vary in size, shape, and function and may contain many types of organelles. 3. tissue level Tissues are groups of similar cells that perform a specific function. There are four major types of tissues in the human body: a. epithelial tissue It is found lining body cavities and covers the surface of the body. It functions in  protection, secretion, and excretion. b. connective tissue It is found on the surfaces of  and in organs and tissues and functions in protection, support, and attaching organs and tissues to each other and to the walls of body cavities. c. muscle tissue It functions in the movement of body parts and organs, and in the movement of substances throughout the body. There are three major types of muscle tissue: (1) skeletal muscle It is found attached to and covering bones and it functions in body movement. (2) cardiac muscle It is located in the heart wall and functions in the contraction and relaxation of the heart as it beats. (3) smooth muscle It is located in the walls of internal or visceral organs and it functions in moving substances throughout the body. d. nervous tissue  It is located in the brain and  spinal cord, and extends to various tissues and organs.  It  functions in transmitting electrical or nerve impulses from the external and internal environments to the brain and spinal cord where it is interpreted and a response occurs. 4. organ level Organs are groups of two or more types of  tissue working together to perform a specific function. 5. organ system level ~ sTstems are groups of organs that work closely together to perform a common function. There are eleven organ systems in the human body: ao g. h. i. j. k. integumentary system muscular system skeletal system nervous system endocrine system cardiovascular system lymphatic system respiratory system digestive system urinary system reproductive system 6. organismal level It is the highest level of structural organization and it consists of groups of organ systems working together to maintain body structure and function. Organ systems work together to maintain an internal environment that is fairly constant, stable, or balanced. This is referred to as homeostasis (to stay the same). Changes do occur, but within very narrow ranges or limits. Homeostasis Body parts or structures function efficiently in maintaining metabolic processes and when the survival needs are within certain limits or optimum levels. The survival needs include: water,  oxyqen, nutrients, an appropriate bod~ temperature, and atmospheric pressure. Water is necessary for chemical reactions, excretion, and secretion.  Oxyqen is required for many of the metabolic  reactions that break down nutrients and provide energy. Nutrients provide energy for cells and cell processes. Bod~ temperature must be maintained within a certain range for chemical reactions and cell processes to perform efficiently. If the body temperature falls too low or increases too high, chemical reactions will slow down or may stop. Atmospheric pressure is the force of air on the body surface by the weight of air. It is important in breathing and in the exchange of oxygen and carbon dioxide in the lungs. To maintain homeostasis there are control mechanisms. Control mechanisms consist of three parts: i. receptor It responds to sensory stimuli from the internal and external environments. The information is sent along afferent pathways to the control center. 2. control center It consists of the brain and spinal cord which interpret and analyze the information and determine an appropriate response.  Information is then sent along efferent pathways to the effector. 3. effector It consists of tissues, organs, or glands that perform a motor response to the original stimulus that was received by the receptor. The response involves a feedback mechanism. If the response slows down or inhibit~ the stimulus it is a neqative feedback mechanism. If the response speeds up or enhances the stimulus, it is a positive feedback mechanism. Most control mechanisms for homeostasis in the human body are negative feedback mechanisms.