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.

9/11 Terrorism Attacks Essay Example for Free

9/11 Terrorism Attacks Essay ? After the September 11 World Trade Center Attacks, America had had second thoughts about their immigration law. On September 11, 2001, four commercial planes were hijacked in the US. Using the planes as bombs, the hijackers flew two into the World Trade Center in New York City; one was flown into the Pentagon in Washington DC, and the fourth crashed in Pennsylvania. Over 6,000 people were killed, most when the World Trade Center collapsed. The FAA immediately grounded all US planes to prevent further attacks. The 19 men who hijacked the planes were foreigners who had been in the US from a week to several years. At least 16 entered at US ports of entry, with student or tourist visas; some of their visas appear to have expired before September 11, 2001. About 40 percent of the 8. 5 million unauthorized foreigners in the US similarly entered with seemingly valid visas, but did not abide by the terms of their visa by e. g. departing within 90 days. (Martin & Martin, October 2001) Our enemies have repeatedly exercised this option of inserting terrorists by exploiting weaknesses in our immigration system. A Center for Immigration Studies analysis of the immigration histories of the 48 foreign-born Al-Qaeda operatives who committed crimes in the United States from 1993 to 2001 (including the 9/11 hijackers) found that nearly every element of the immigration system has been penetrated by the enemy. (Camarota, 2002) Of the 48, one-third were here on various temporary visas, another third were legal residents or naturalized citizens, one-fourth were illegal aliens, and the remainder had pending asylum applications. Nearly half of the total had, at some point or another, violated existing immigration laws. 9/11 was not the only terrorist plot to benefit from lax enforcement of ordinary immigration controls—every major Al-Qaeda attack or conspiracy in the United States has involved at least one terrorist who violated immigration law. Gazi Ibrahim Abu Mezer, for example, who was part of the plot to bomb the Brooklyn subway, was actually caught three times by the Border Patrol trying to sneak in from Canada. The third time the Canadians would not take him back. What did we do? Because of a lack of detention space, he was simply released into the country and told to show up for his deportation hearing. After all, with so many millions of illegal aliens here already, how much harm could one more do? Another example is Mohammed Salameh, who rented the truck in the first World Trade Center bombing. He should never have been granted a visa in the first place. When he applied for a tourist visa he was young, single, and had no income and, in the event, did indeed end up remaining illegally. And when his application for a green card under the 1986 illegal-alien amnesty was rejected, there was (and remains today) no way to detain and remove rejected green-card applicants, so he simply remained living and working in the United States, none the worse for wear. (Krikorian, 2004) Immigration Changes According to Daniel T. Griswold (2002) â€Å"We should not allow the war on terrorism to be hijacked by those who would turn it into a war on immigration. Members of the Immigration Reform Caucus and writers in National Review have tried to hitch their anti-immigration agenda to legitimate concerns about border security in our post-9-11 world. But â€Å"border control† and immigration are two separate issues. The problem is not that we are letting too many people in but that the federal government has not been doing enough to keep the wrong people out† Philips and Susan Martin stressed that The federal government immediately made some immigration changes in response to the terrorist attack, such as holding foreigners who violate immigration laws 48 hours without charge, up from 24 hours. But the Bush administration is seeking more immigration changes, and the new Homeland Security Council, with 100 staff members comparable in size to the National Security Council staff, is likely to suggest even more as the 46 federal agencies whose work it coordinates to fight terrorism review the processes of issuing visas to foreigners, controlling their entry into the US, and ensuring that they abide by the terms of their visas inside the US. Immigration policy reforms can not prevent terrorism, but they are a key part of any effort to combat terrorism. Immigration policies aim to facilitate the entry of wanted foreigners, and to identify and deter the entry of terrorists and other unwanted foreigners. This paper outlines the immigration reforms that could help prevent the entry of future terrorists. It would be unfair and self-destructive to blame America’s immigration policy for what happened on September 11. Immigrants come to live and work and build a better life for themselves and their families. The terrorists did not come here as immigrants. They entered the country on temporary non-immigrant tourist and student visas. They didn’t apply to the INS for green cards or any other kind of permanent status. Immigrants are only a small subset of the much larger pool of 30 million foreign nationals who enter the United States in a typical year. More than 95 percent enter as tourists or business travelers. Only 3 percent, or about one million, enter to immigrate, that is, to settle here permanently. We could reduce immigration to zero and it would do nothing for our national security. (Griswold, 2002) 9/11 Terrorism Attacks. (2017, May 03).

Virtual Teams Essay Example | Topics and Well Written Essays - 750 words - 1

Virtual Teams - Essay Example And within this culture it is necessary for each individual to take his won developmental path, which is actually the core of the functioning of virtual organizations. Virtual Teams have become an integral part of many organizations because of all increase in corporate restructuring, competition, and globalization. A virtual team is also defined as one that conducts its work almost entirely through electronic technology. Virtual team members, who are normally isolated both geologically and organizationally, hardly ever meet face to face while relying on technology for task-related communication (Matthews-Joy & Gladstone, 2000). Because communication is often seen as the most important factor in coordinating work among team members, effective communication is vital for virtual teams. However, "in virtual teams, separated by geographical distance, the process of developing a shared understanding is more challenging" (Ancona & Caldwell, 1992). In particular, such teams must address three challenges to accomplish their goals. The first challenge is compensating for the lack of face-to-face interaction. When meeting in person, team members can depend upon voice levels, smiles, and raised eyebrows to determine whether they are being understood; however, virtual teams do not have these nonverbal cues and can fail without communication strategies to manage the lack of face-to-face communication or silence. Because research continues to support the findings of Mehrabian that communication is predominately nonverbal, virtual team members lack one of the primary elements for generating shared understanding. Even in the best videoconferencing, facial expressions can be difficult to pick up if the transmission is poor, if someone is off camera, or when the mute button is pressed. Therefore, it is essential for individuals who are about to become part of a virtual teaming experience to be sensitized to the importance of this barrier and how it may be addressed. Second Challenge A second communication challenge for virtual teams is building relationships. Successful teams are founded on a relationship of trust, and relationships are easier to build face to face. Virtual teams are confronted with the challenge of establishing trusting working relationships through technological interaction alone. Virtual team leaders need to pay close attention to the first interactions team members have with each other to support the creation of positive interpersonal relationships. People who are being prepared for participation in virtual teams need to be taught methods of increasing the likelihood of getting off on the right foot with each other. Third Challenge A third challenge is accessing and leveraging the unique knowledge of each member to successfully achieve the team's goal. While a team is working on a project, usually the project is like a puzzle, and each team member is responsible to work on an assigned piece of the project. The team must develop a system for sharing information so that nothing relevant to solving the problem is lost. What some team members may consider the most insignificant piece of information may prove to be critical to the final solution. Whereas

Wall street journal Essay Example | Topics and Well Written Essays - 1250 words - 2

Wall street journal - Essay Example It has also been equipped with Apple’s Touch ID fingerprint reader. The Touch ID allows users to purchase items within apps by using Apple Pay payment services in addition to also acting as a security feature (Wakabayashi, 2014). In July 2013, Apple announced that it would work with International Business Machines Corp so as to develop iPad and iPhone apps that would cater to the workplace. By positioning the iPad as a possible PC replacement for the newly emergent generation of workers, Apple is noted to be aiming at attempting to answer the existential question noted to be facing tablet computers as technology continues to evolve. As smartphones continue to grow bigger with more powerful processors and larger screens, this trend is noted to be visible in Apple’s own products as is demonstrated in the case of the newly released iPhone 6 plus which comes with a 5.5-inch display that is nearly encroaching on iPad Mini’s 7.9-inch screen. Having been the first tablet computer in 2010, Wakabayashi (2014) points out that the iPad was largely a runaway success but demand for the product has started to gradually slow. A key reason as to why the sale of tablets is gradually decreasing is that people that own iPads are not replacing their tablet computers nearly as often as they tend to swap their phones. It is estimated that about 46% of the iPads that are currently in use are the original iPad and iPad 2 that were initially introduced in 2010 and 2011 respectively. The new iPad Air 2 is largely expected to help drive what will be â€Å"an upgrade cycle† among the currently existing owners of iPads. Other than the iPad Air 2, Apple also plans on unveiling a new iPad Mini 3, that will come with Touch ID as well as a new iMac personal computer. To compete with lower priced rivals that run Google Inc’s Android operating system, Apple cut the price of last year’s iPad model down to $299 while that for its previous iPad minis was reduced to $249. Apple is also

Concideration of fraud in an audit Research Paper

Concideration of fraud in an audit - Research Paper Example FRAUD Fraud is a word used in broader concepts and approaches. It basically refers to any illegal action characterized by deceit and concealment which isn’t conducted under any violence, force or threat. The aim of every fraudulent activity is an undue advantage which could be institutional or personal. (Flostoiu.2012) Characteristics of Fraud: Fraud results in victim that loses a benefit because of the criminal’s fraud. It is represented by a series of illegal actions and irregularities which are all planned with the intention to deceive. Fraud is also referred to activities which involve concealment of information that was to be revealed by an obligation and intended omission of certain information or documents including misstatements and misrepresentation of information. Fraud also includes falsification of financial situations, corruption and theft. It is always important to distinguish between a fraud and error. The results of both error and fraud could be the same , but fraud is committed intentionally while error happens unintentionally. (Flostoiu.2012) Fraud Triangle Theory: A fraud triangle is a model which discloses the factors found in fraudsters at all levels of organization. This theory researched about the factors that force honest people to commit fraud. These factors could be summed as Pressure/Incentive, Opportunity and Rationalization that put an individual in a position to conduct fraud. (Dorminey, Scott, Kranacher & Riley. 2010) In a Fraud Triangle pressure refers to situations that put mental pressure/incentive on an individual which forces him to commit fraud. These situations could include excessive credit card debts, gambling debts, extended unemployment, family or peer pressures, unbearable expenditures and financial difficulties etc. For an auditor, pressure is difficult to identify in a fraudster as there is no personal interaction with him. (Dorminey, Scott, Kranacher & Riley. 2010) Opportunity as the word suggests, is a n instance where the fraudster finds a loophole in the controls which prevent fraud. An employee usually finds a chance where he can commit fraud without being detected. This opportunity for an employee can arise from weak internal controls and inability of frauds being detected, lack of training, weak ethical culture where honesty in doing business isn’t considered a priority and lack of supervision etc. Most opportunities arising situations for fraud include lack of internal controls like segregation of duties not being implemented properly. (Dorminey, Scott, Kranacher & Riley. 2010) Rationalization refers to that state of mind where the fraudster convinces himself that whatever fraud he has committed was either not wrong or even it was wrong it an be corrected later on by returning the money or compensating for it. Another state of rationalization is found when a fraudster convinces himself that he deserves the stolen money. The reason for this rationalization could be the unfair treatment in the organization like a recent promotion or increment not being offered which forces him to believe that has been victimized. (Kassem, Rasha, & Higson, Andrew. 2012) Recent researchers have extended the Fraud Triangle and added a fourth factor to the triangle making it as a diamond. This factor is the capability of the fraudster to conduct fraud. Capabilities include the traits of the fraudster i.e. in presence of the three factors of fraud

An introduction to accounting Essay Example | Topics and Well Written Essays - 750 words

An introduction to accounting - Essay Example Accounting may not be popular but it is a must for any organisation,be it in the manufacturing or service sector, whatever its size,whichever country it is based in and whether or not its aim is to maximise profits.Without accounting resources cannot be managed effectivelyIt is irrefutable that any business organization requires the use of accounting. In fact, the use of accounting dates back from the time a business organization is formed. A company cannot function efficiently without the use of a system which list down the financial transactions that it undertakes (Atrill and McClaney 2001). In the simplest sense, accounting can be defined as the system which provides information about the financial situation of an organization.Since accounting is all about recording financial transactions, it is then a necessity for any organization which deals with money (Atrill and McClaney 2001). And looking at the global business situation right now, no business entity is ever existent without financial resources. Accounting provides a systematic and comprehensive way of recording a company's financial transactions. For one, the accounting equation serves as the basis of the company's financial statements recognizing the principle of double-entry bookkeeping in accounting. The accounting equation is as follows: assets less liabilities = shareholders' equity. It can also be expanded as: assets less liabilities = shareholders' equity (revenue less expenses)(Keown et al 2005). ... Accounting aids a business organization to gather three types of information namely operating, financial, and managerial (Atrill and McClaney 2002). All companies are required to use accounting for operating purposes or for daily activities in order to record and determine the amount of salary owed to workers, track sales, and level of inventory. Secondly, financial information is also needed in order to attract shareholders and creditors. The company often needs to prove to these providers of financial aid that it is worthy of receiving resources. Thus, a company should record transactions and report them to these interested entities. Lastly, accounting is used for decision making. Companies are interested to know how much inventory should be produced in a given month, whether to manufacture in-house or source from a supplier, whether to acquire a new equipment or not. It should be noted that the purposes and information provided by accounting is used by any business organization whether from the goods or service sector. As long as there is money involved, transactions are irrefutably recorded. The financial resources are tracked through accounting. For one, the most common goal of a company which is to make money can only be evaluated if financial transactions are constantly monitored and recorded systematically. A business can only know whether it makes money or not when it employs a system which tracks its revenue and its expenses. However, it should also be stressed that accounting is also required even for not-for-profit business organizations. Non-government organizations like Red Cross and Youth for Christ employ accounting to record their expenses and budget

The Importance of Accurate Language in Professions Essay

The Importance of Accurate Language in Professions - Essay Example Apart from educational qualifications, communication skills are mandatory for any kind of profession. Ardener indicates that in the field of anthropology, use of language cannot be alienated from success in the job (16). Anthropology requires accurate use of language among the interpreters of a particular form of language so that the message can be interpreted as much accurately to the targeted audience. It is recommended that anthropologists and career people in the field of anthropology be endowed with the linguistic ability of discerning the various language structures and categorization of various languages (Ardener 17). In this case, it is justified to argue that accuracy in communication in the field of anthropology must not be jeopardized by any means in the society. It is vital that all anthropologists be conversant with various linguistic structures of the languages they deal with in their course of