Solar Energy

A new solar powered adsorption refrigerator with high performance Meunier published a comparison of those three sorption systems for solar cooling (Meunier, 1994). The solid-gas system used in the present study is adsorption. The solar adsorption refrigerators have been developed mainly to be used in hot regions with no electricity supply. There is an urgent need in the health sector (for the conservation of medicines and vaccines). These systems have the advantage of not requiring any energy other than solar energy.Regarding performance, the highest values of COPSR (0. 10-0. 12) were obtained with the adsorption systems zeolite + water (Grenier et al. , 1988) and activated carbon + methanol (Boubakri et al. , 1992a,b; Pons and Grenier, 1987). As methanol can easily evaporate at temperatures below O oc, thus favouring the production of ice, the most environmentally friendly refrigerant must be water. Using water, ice can be produced within the evaporator, acting as a ‘cold stor age'. Both refrigerants, water or methanol, operate at below atmospheric pressure and therefore require vacuum technology. The main urpose of the present study is to obtain what is, technically speaking, a simple machine.This aim seems reasonably achievable with an adsorptive machine, operated in a 100% solar-powered 24 h cycle with a flat-plate solar collector containing the adsorbent. However, when referring to the work reported above, both the efficiency of the solar collector and that of the adsorption thermodynamic cycle could be improved. These requirements were crucial to the design of the ‘advanced' machine. The laboratory of solar energy of the Engineering school of the Canton de Vaud (EIVD, Yverdon-lesBains, Switzerland) has been eveloping adsorptive solar refrigerators since 1999. The first systems built used the adsorption pair of activated carbon + methanol.For reasons of reliability and respect for the environment, this pair has been abandoned in favour of a sili cagel + water pair. The prototype described and analyzed in this paper has been functioning since the summer of 2000 on the site of the EIVD. A thorough measurement system allows us to characterise it in a complete way. During the summer of 2001, a constant procedure of thermal load in the cold cabinet allowed us to observe the behaviour of the adsorption system over a continuous period of 68 ays. We have highlighted the great influence of both external temperature and daily irradiation upon the daily coefficient of performance (COPSR ). Previously, few articles were interested in the analysis of the storage. 2.Description of adsorption and of the adsorption cooling cycle Adsorption, also known as physisorption, is the process by which molecules of a fluid are fixed on the walls of a solid material. The adsorbed molecules undergo no chemical reaction but simply lose energy when being fixed: adsorption, the phase change from fluid to adsorbate (adsorbed phase) is exothermic. Moreover this process is reversible. In the following, we will focus on adsorption systems mainly used in cooling (or heatpumping) machines: a pure refrigerant vapour that can easily be condensed at ambient temperature and a microporous adsorbent with a large adsorption capacity.The main components of an adsorptive cooling machine are the adsorber (in the present case, the solar collector itself), the condenser, the evaporator and a throttling valve between the last two devices, see Fig. 2. An ideal cycle is presented in the D‚ ¬hring diagram (LnP vs. †¦I=T), Fig. 1. 2001). We can summarize it in four stages. C. Hildbrand et al. / solar Energy 77 (2004) 311-318 13 Fig. 1 . An ideal adsorption cooling cycle in the D‚ ¬ hring diau gram. Saturation liquid- vapour curve for the refrigerant (EC dashed line), isoster curves (thin lines), adsorption cycle (thick lines). Heating period: step AB (7 a. m. fl 10 a. m. ) and step BD (10 a. m. fl 4 p. m. ); cooling period: step DF ( 4 p. m. fl 7 p. m. ) and step FA(7 p. m. fl 7 a. m. ).Step 1: isosteric heating  ¶A ! BD. The system temperature and pressure increase due to solar irradiance. Step 2: desorption + condensation dB ! DD. Desorption of the water steam contained in the silicagel; condensation of the water steam in the ondenser; the water in the evaporator is drained through the valve. Step 3: isosteric cooling ?D ! FP. Decrease of the period of sunshine; cooling of the adsorber; decrease of the pressure and the temperature in the system. Step 4: adsorption + evaporation  ¶F ! AD. Evaporation of water contained in the evaporator; cooling of the cold cabinet; production of ice in the evaporator; readsorption of water steam by the silicagel. 3.Description of the machine tested in Yverdon-les-Bains, Switzerland Adsorptive pair. The refrigerant is water, and the adsorbent is a microporous silicagel (Actigel SG ¤ , Silgelac). Collector-adsorber. The solar collector (2 m2 , tilt angle of 300) is double- glazed: a Teflon ¤ film is installed between the glass and the adsorber itself. The adsorber consists of 12 parallel tubes (72. 5 mm in diameter) that contain the silicagel (78. 8 kg). The tubes are covered with an electrolytic selective layer (Chrome-black, Energie Solaire SA), which absorbs 95% of the visible solar radiation while presenting an emissivity of 0. 07 in the infrared wave-lengths.A valve located between the graduated tank and the evaporator is needed on this machine. For control strategy reasons, this valve is electrically powered. 4. 5. Ventilation damper management Closing: when the irradiance goes above 100 W/m2 . Opening: at the end of the afternoon when the angle of the solar beam radiation incident upon the aperture plane of collector (angle of incidence) is above 500. 4. Measurements and operations The objective of the 2001 series of measurements was to obtain a high number of measurements continuously, in order to characterise he working of our adsorption ma chine. To do this, a system of measurement and a constant procedure of load has been established. 4. 1.Measurements The temperature is measured (probes Pt100) in the silicagel of a central tube of the collector-adsorber (7 sensors), on two condenser tubes and three evaporator tubes; and the ambient air temperature is also measured. The vapour pressure is measured by a piezogauge in the collector-adsorber, in the condenser and in the evaporator. The global irradiance in the plane of the collector is recorded by a pyranometer. A graduated tank (6. 5 1) collects the condensed water. The level of liquid water is automatically measured by a level detector. The series of measurements took place from July 25th to September 30th 2001 (68 days) in Yverdon-lesBains (altitude: 433 m, longitude: )6. 380, latitude: 46. 470). Fig. 3 shows the observed weather conditions (daily irradiation and mean external temperature).This graph shows two different periods: (1) From July 25th to the beginning of September: during this summer period, the mean external temperature is above 20 oc and the mean daily irradiation reaches 22 MJ/m2 . This fine weather period is interrupted between the 3rd and 9th August by ess favourable weather. (2) From the beginning of September to the end of the measurement: the mean external temperature and the daily irradiation are distinctly lower (13 oc and 13 MJ/m2 ). Furthermore, the conditions are very variable from one day to the next. 4. 2. Acquisition system and command 6. Performance of the tested unit A Labview ¤ program takes measurements and administers various commands (valve, dampers and load). A measurement is made every 30 s.

Assignment 3-2 Essay Example | Topics and Well Written Essays - 750 words

Assignment 3-2 - Essay Example This pattern emerges when we study the dominant traits of all the individuals in the group. Just as the personality profiles of individuals can be used to understand their interactions; the personality profiles of individuals and groups can also be studied to understand the extent of fit that the individual has with the group. Such analysis can often help us identify helpful and unhelpful patterns between levels in the hierarchy; co-workers, and thus help us repair the same to ensure efficient functioning of the group. In the present study, the group supervisor has a personality profile that can be coded as ESFP, and the group he supervises is coded has a dominant profile ESTJ. We find it important to study the interaction between these two profiles in order to try and understand the areas of strength and those of concern in the interactions of the supervisor and the group. The supervisor (personality profile ESFP) is a spontaneous, outgoing individual who loves attention and being a mongst people; interacting with them and helping them feel good about themselves. He makes a great team worker because of this. This person is also liable to be emotional in some situations, and moody in his interactions with others. He prefers using pre-existing structures to new ones; and is less likely to be analytical about the situation at hand. On the other hand, the group profile suggests that the group is organised and focused in its functioning and prefers to abide by rules and structures. It respects authority and is meticulous in its functioning. The discipline that the group seems to love keeps in on target in its goals, which also fuels its sense of purpose and confidence. The group does not take lightly to erratic and strange or out-of context behaviour. Its strong centrifugal style keeps the group connected and united in most cases. The relationship between these two groups is seen as one of Benefit; with the supervisor (personality profile ESFP) being the Benefactor of the group (personality profile ESTJ). A relationship of this kind gives the benefactor a more favourable place in the relationship; and thus, a higher place in the hierarchy. The relationship is mutually beneficial to the extent that the benefactor – here the supervisor – provides the presence and authority that the beneficiary needs and craves. This makes for a smooth work relationship in most cases, since the supervisor provides the authority and direction the team happily follows in the completion of the set goals. The supervisor in return gains respect from the team that provides a sense of authority and control the ESFP love. The team or group tend to identify with the supervisor and treats itself as an extension of this supervisor, such that the flow of command and direction is seamless and rarely challenged. There are potential areas of conflict also; since the supervisor does have some weak spots that the group tries to fill out. But being lower in the hiera rchy of power; they can only make suggestions that may or may not be conceded. This can lead to strife and angry interactions that taint the mood of the group; and could even affect it’s functioning. The supervisor’s personality does lead him to undervalue to inputs of the group; and may ignore suggestions from the team members. While they are focussed on maintaining the wellbeing and functionality of each team member; they do not feel the need to take all

Should women be allowed in combat (yes) arguing for the issue Research Paper

Should women be allowed in combat (yes) arguing for the issue - Research Paper Example First, women who comprise almost 14 percent of the armed forces should be allowed to serve fully in front- line combat units because they have proven themselves to be mentally, morally, and physically able to lead and execute combat-type operations (Healey, 57). As a result, some of these female marines feel qualified for the opportunity of taking on the role. My personal experience has been that women are as good leaders and team builders as men. I have noticed that women have good interpersonal and communication skills. They are good at taking orders; they are careful, keen and observant, and incorporating them in the combat can make it very successful (express.co.uk). Secondly, there is no clear evidence that integrating women soldiers into military operations or previously closed units damages cohesion or has other ill effects. In fact and independent report has suggested that women who serve in combat in Afghanistan and Iraq had a positive impact on the accomplishment of the mission (King, 409). Allowing women in the military makes the army looks normal to the society and increases its operational capability. General Sir Peter Wall put is that "they are fundamental to the operational effectiveness of the UKs Armed Forces, bringing talent and skills across the board† (express.co.uk).   Allowing women in combat creates a mixed gender force thus keeping the military strong. Deploying and recruiting women who are in better shape is much easier than many men who are sent in combat. Over the years I have realized that women are as intelligent as men and a woman, who commits into doing something, always does it perfectly (express.co.uk). Lastly, women should be allowed in combat because it will elevate their status in the military. Combat duty is often necessary for promotion to senior positions, therefore, denying female personnel the experience further entrenches sexism as very few will reach the highest

Philosophy Essay Example | Topics and Well Written Essays - 500 words - 24

Philosophy - Essay Example These are unanswered questions, though various religions offer guidance in this respect. People have made predictions in the past about the end of time also; â€Å"Annie Stanton predicted that a 14.4 mile long asteroid will collide with the earth. Jesus will arrive and a 1000 year period of peace will start.† (Robinson, 2007). No one can tell whether time is a property of the universe or vice versa. Despite the enormous confusion about time, I believe it did always exist and it is immortal, yet the parameters to measure time were different before the formation of universe and will change after the universe will come to an end on the Doom’s day. Man is born with an intrinsic urge to realize the sequence of the worldly matters, and this is what shaped the time for man in the world. Man derives the system of time from the regularity in the routine of nature. Everyday, the sun rises at a certain time and sets at a certain time. It keeps happening so until summers convert into winters to squeeze the time shorter. After the winter season, day starts to elongate. But the changes observed in the solar length of a day over one year keep repeating in the same fashion every year. This caused man to associate his daily activities with the shifts of day and night. Our circadian rhythms are designed and governed by the sunrise and sunset. The routinely motion of Earth around the sun h as the power to harmonize the man’s internal chemistry. The origin of the modern system of time, which everybody follows today, is associated with the birth of Christ. But scientific research on the now-extinct species of animals like dinosaurs suggests that the world had been there trillions of years ago, though such statements are only estimations and have little to do with reality. Everyday a new theory emerges that sidelines the previous one. Various religions teach about the existence of time even after the end of

Politics around the world.comparative assignment

Politics around the world.comparative - Assignment Example There has been a lot of debate in the United States recently on the issue of offering public health care. How does U.S. spending on health care actually compare to other countries? The following will explore data available from the Organization for Economic Co-operation and Development (OECD), which maintains a statistical database on all of its member states: http://www.oecd.org Under the topics menu, select â€Å"Health.† Then follow the link for â€Å"OECD Health Data 2014: Key indicators.† Click on the link that reads: â€Å"DOWNLOAD this selection of key indicators from OECD Health Statistics 2014 in Excel† Use this excel file to answer the following questions. In all cases, please report the data for 2012. every citizen to have health insurance. The rich are in Germany are allowed to pay for their own insurance from the insurer of their choice while the poor get social assistance from the government. The Japanese get their insurance from their employers or from a nonprofit insurance organization. In Switzerland the healthcare system is also similar to that of Japan and Germany whereby citizens get social insurance and the poor are assisted by the government which does not happen in the U.S as the poor are left to struggle on their own to find medical assistance. The Taiwan citizens also enjoy a national health insurance system like the most of other developed countries which means that the poor can afford to get decent health care unlike in the U.S where that is impossible (Frontline,

Arabic Culture Essay Example | Topics and Well Written Essays - 500 words

Arabic Culture - Essay Example he gender division of roles, responsibilities and resources within the household play an important role in shaping what men and women are able to do beyond the household. Islamic texts and traditions lie at the heart of Arab cultural conventions. Critics have seized upon the way that the exact interpretation of religious doctrines varies from state to state, and stress that it is important to reflect on who is making the rules for gender roles and activities, namely men, and how little real choice women have. The definition of what is a matter of culture and religion, and what is a matter of human rights is contentious. Handrahan, for example, compares the human rights offences which occurred in apartheid South Africa with the treatment of women in Arabian culture and describes the Arabian situation as â€Å"gender apartheid† (Handrahan 9) The absence of equal voting rights for women is quite obviously matter of serious discrimination and it attracts condemnation from critics both inside and outside Arabia. A woman’s identity in Arabian culture and society is constructed, in the very first place, on the basis of men’s superiority. Such discriminated gender growth is justified on both cultural and religious basis. In a rigidly religious society, men’s superiority and women’s dependency on men are ratified by the following verse of the Holy Quran: â€Å"Men are the protectors and maintainers of women, because Allah has given the one more (strength) than the other, and because they support them from their means. Therefore the righteous women are devoutly obedient, and guard in (the husbands) absence what Allah would have them guard† (Quran  4:34). Indeed this verse is one of many from the Holy Quran that the clerics of the society manipulate to enact rules, regulations and laws that slaughter women’s equality to men. Some of these rules and regulations are male guardianships, Namus, Purdah, Dress codes, sexual segregation, etc. One of the common aftermaths

Research Papers in Computer Science Essay Example for Free

Research Papers in Computer Science Essay Since we recently announced our $10001 Binary Battle to promote applications built on the Mendeley API (now including PLoS as well), I decided to take a look at the data to see what people have to work with. My analysis focused on our second largest discipline, Computer Science. Biological Sciences (my discipline) is the largest, but I started with this one so that I could look at the data with fresh eyes, and also because it’s got some really cool papers to talk about. Here’s what I found: What I found was a fascinating list of topics, with many of the expected fundamental papers like Shannon’s Theory of Information and the Google paper, a strong showing from Mapreduce and machine learning, but also some interesting hints that augmented reality may be becoming more of an actual reality soon. The top graph summarizes the overall results of the analysis. This graph shows the Top 10 papers among those who have listed computer science as their discipline and chosen a subdiscipline. The bars are colored according to subdiscipline and the number of readers is shown on the x-axis. The bar graphs for each paper show the distribution of readership levels among subdisciplines. 17 of the 21 CS subdisciplines are represented and the axis scales and color schemes remain constant throughout. Click on any graph to explore it in more detail or to grab the raw data.(NB: A minority of Computer Scientists have listed a subdiscipline. I would encourage everyone to do so.) 1. Latent Dirichlet Allocation (available full-text) LDA is a means of classifying objects, such as documents, based on their underlying topics. I was surprised to see this paper as number one instead of Shannon’s information theory paper (#7) or the paper describing the concept that became Google (#3). It turns out that interest in this paper is very strong among those who list artificial intelligence as their subdiscipline. In fact, AI researchers contributed the majority of readership to 6 out of the top 10 papers. Presumably, those interested in popular topics such as machine learning list themselves under AI, which explains the strength of this subdiscipline, whereas papers like the Mapreduce one or the Google paper appeal to a broad range of subdisciplines, giving those papers a smaller numbers spread across more subdisciplines. Professor Blei is also a bit of a superstar, so that didn’t hurt. (the irony of a manually-categorized list with an LDA paper at the top has not escaped us) 2. MapReduce : Simplified Data Processing on Large Clusters (available full-text) It’s no surprise to see this in the Top 10 either, given the huge appeal of this parallelization technique for breaking down huge computations into easily executable and recombinable chunks. The importance of the monolithic â€Å"Big Iron† supercomputer has been on the wane for decades. The interesting thing about this paper is that had some of the lowest readership scores of the top papers within a subdiscipline, but folks from across the entire spectrum of computer science are reading it. This is perhaps expected for such a general purpose technique, but given the above it’s strange that there are no AI readers of this paper at all. 3. The Anatomy of a large-scale hypertextual search engine (available full-text) In this paper, Google founders Sergey Brin and Larry Page discuss how Google was created and how it initially worked. This is another paper that has high readership across a broad swath of disciplines, including AI, but wasn’t dominated by any one discipline. I would expect that the largest share of readers have it in their library mostly out of curiosity rather than direct relevance to their research. It’s a fascinating piece of history related to something that has now become part of our every day lives. 4. Distinctive Image Features from Scale-Invariant Keypoints This paper was new to me, although I’m sure it’s not new to many of you. This paper describes how to identify objects in a video stream without regard to how near or far away they are or how they’re oriented with respect to the camera. AI again drove the popularity of this paper in large part and to understand why, think â€Å"Augmented Realityâ€Å". AR is the futuristic idea most familiar to the average sci-fi enthusiast as Terminator-vision. Given the strong interest in the topic, AR could be closer than we think, but we’ll probably use it to layer Groupon deals over shops we pass by instead of building unstoppable fighting machines. 5. Reinforcement Learning: An Introduction (available full-text) This is another machine learning paper and its presence in the top 10 is primarily due to AI, with a small contribution from folks listing neural networks as their discipline, most likely due to the paper being published in IEEE Transactions on Neural Networks. Reinforcement learning is essentially a technique that borrows from biology, where the behavior of an intelligent agent is is controlled by the amount of positive stimuli, or reinforcement, it receives in an environment where there are many different interacting positive and negative stimuli. This is how we’ll teach the robots behaviors in a human fashion, before they rise up and destroy us. 6. Toward the next generation of recommender systems: a survey of the state-of-the-art and possible extensions (available full-text) Popular among AI and information retrieval researchers, this paper discusses recommendation algorithms and classifies them into collaborative, content-based, or hybrid. While I wouldn’t call this paper a groundbreaking event of the caliber of the Shannon paper above, I can certainly understand why it makes such a strong showing here. If you’re using Mendeley, you’re using both collaborative and content-based discovery methods! 7. A Mathematical Theory of Communication (available full-text) Now we’re back to more fundamental papers. I would really have expected this to be at least number 3 or 4, but the strong showing by the AI discipline for the machine learning papers in spots 1, 4, and 5 pushed it down. This paper discusses the theory of sending communications down a noisy channel and demonstrates a few key engineering parameters, such as entropy, which is the range of states of a given communication. It’s one of the more fundamental papers of computer science, founding the field of information theory and enabling the development of the very tubes through which you received this web page you’re reading now. It’s also the first place the word â€Å"bit†, short for binary digit, is found in the published literature. 8. The Semantic Web (available full-text) In The Semantic Web, Tim Berners-Lee, Sir Tim, the inventor of the World Wide Web, describes his vision for the web of the future. Now, 10 years later, it’s fascinating to look back though it and see on which points the web has delivered on its promise and how far away we still remain in so many others. This is different from the other papers above in that it’s a descriptive piece, not primary research as above, but still deserves it’s place in the list and readership will only grow as we get ever closer to his vision. 9. Convex Optimization (available full-text) This is a very popular book on a widely used optimization technique in signal processing. Convex optimization tries to find the provably optimal solution to an optimization problem, as opposed to a nearby maximum or minimum. While this seems like a highly specialized niche area, it’s of importance to machine learning and AI researchers, so it was able to pull in a nice readership on Mendeley. Professor Boyd has a very popular set of video classes at Stanford on the subject, which probably gave this a little boost, as well. The point here is that print publications aren’t the only way of communicating your ideas. Videos of techniques at SciVee or JoVE or recorded lectures (previously) can really help spread awareness of your research. 10. Object recognition from local scale-invariant features (available in full-text) This is another paper on the same topic as paper #4, and it’s by the same author. Looking across subdisciplines as we did here, it’s not surprising to see two related papers, of interest to the main driving discipline, appear twice. Adding the readers from this paper to the #4 paper would be enough to put it in the #2 spot, just below the LDA paper. Conclusions So what’s the moral of the story? Well, there are a few things to note. First of all, it shows that Mendeley readership data is good enough to reveal both papers of long-standing importance as well as interesting upcoming trends. Fun stuff can be done with this! How about a Mendeley leaderboard? You could grab the number of readers for each paper published by members of your group, and have some friendly competition to see who can get the most readers, month-over-month. Comparing yourself against others in terms of readers per paper could put a big smile on your face, or it could be a gentle nudge to get out to more conferences or maybe record a video of your technique for JoVE or Khan Academy or just Youtube. Another thing to note is that these results don’t necessarily mean that AI researchers are the most influential researchers or the most numerous, just the best at being accounted for. To make sure you’re counted properly, be sure you list your subdiscipline on your profile, or if you can’t find your exact one, pick the closest one, like the machine learning folks did with the AI subdiscipline. We recognize that almost everyone does interdisciplinary work these days. We’re working on a more flexible discipline assignment system, but for now, just pick your favorite one. These stats were derived from the entire readership history, so they do reflect a founder effect to some degree. Limiting the analysis to the past 3 months would probably reveal different trends and comparing month-to-month changes could reveal rising stars.