Thursday, May 21, 2020

Fate, Freewill, and The Autobiography of Malcolm X Essay

Fate, Freewill, and The Autobiography of Malcolm X Malcolm X, as a character in his Autobiography, believed that fate and prophecy guided his life. When he was sent to jail for ten years, he believed that his incarceration was part of his predetermination to find Allah in the Nation of Islam; it didnt ever dawn on him that he was solely responsible for his time in prison. Malcolm viewed his indefinite suspension from the Nation as a prophecy he was destined to fulfill, not as an act of jealousy and underhandedness by his fellow Black Muslims. His own violent death was not a surprise to him, for he always had chosen to believe that he would die at the hands of another and that it would be his fate. He did not believe his†¦show more content†¦However, he always believed that a supernatural power, specifically Allah, had planned for him to be caught breaking the law because the coincidental circumstances that led to his imprisonment (and the repercussions of his imprisonment) were too much for Malcolm to accept as chance al one. However much he would like to believe otherwise, it was his own decisions combined with the decisions of others and pure chance that resulted in the years Malcolm X spent in penitentiary. Malcolm X chose to believe that his removal from the Nation of Islam, a decision by a man whom Malcolm believed to be a prophet of Allah, was part of his destiny more than a result of his actions. The Honorable Elijah Muhammad, a man who claimed to be a prophet to Allah (God to those of Islamic faith), had told Malcolm X early in their relationship that they would one day be separated from each other. Malcolm accepted this as prophecy, but one might notice that Elijah was in a position to make this prophecy come true. It did not take Allah to sever Malcolms ties with the Nation of Islam. Elijah could tell that Malcolm would one day rise to a power greater than his, and Elijah provided a means to both add to his public image and have another prophecy become truth. Malcolm chose to believe Elijahs prophecies. Malcolm fooled himself into the simplistic, irresponsible notion of fate. It had always occurred to Malcolm that he would die violently at the hands of an enemy.

Wednesday, May 6, 2020

Competitive Strategies Employed by Retail Supermarkets in...

1. Proposed working title: Competitive strategies employed by Retail Supermarkets in the UK: A comparative study. 2. Research Background: This research background focuses on competitive strategies employed by retail supermarkets in the UK.This background will give a general idea as what to anticipate in the report on strategies approach of leading retail supermarkets of the UK. Retail strategy is an overall plan or the agenda of action that has to follow by the retailer to get the success in the retail supermarket competition. (Barmen, B. Evans, J. 2006).The retail supermarkets environment has become tremendous competitive in recent years .Top supermarkets like Tesco, Asda, Sainsbury and Morrison are heavily investing in†¦show more content†¦Ã¢Å¾ ¢ An attempt to identify which of them are most beneficial for the consumer. 7. LITERATURE REVIEW: My research is on competitive strategies employed by the retail supermarkets in the UK.The information on this topic has been published all over the books, news papers, online journals and web reports. I would like to review some of the most striking opinions given by some authors and my views on it. â€Å"We do not vary our retail offer in line with levels of local competition. We and all the other major grocery multiples have national strategies on pricing, branding, advertising, quality, range and services.† Commented by Tesco (Press association, 2007) I also agree with the author’s view above. Tesco which is number one retail supermarket in the UK decides their strategies by comparing their strong rival’s strategies. Now day’s customers have lot of choice to do shopping because of the competition between retail supermarkets in the UK. Most of the people choose to do shopping on the criteria of pricing, looking at brand and quality of goods and also service provided by the retail supermarkets. I also use same criteria to do my shopping. â€Å"Tosco’s attack on Sainsbury’s southern stronghold reflected a more aggressive store opening programmer. But he also said that Sainsbury, which will this week release interim results, could begin to feel the effects of the credit crunch if consumer worries about weekly shopping billsShow MoreRelatedThe Global Financial Crisis And Its Effects On The Supermarket Industry Essay1518 Words   |  7 Pagessubstitute, working more with equity capital, improving efficiency and re-structuring debt (Beaver and Ross, 1999; Laitinen, 2000; Pearce and Michael; 1997; Zehir, 2005). Studies shows several mitigating effects of the economic downturn in the supermarket industry. The oligopolistic nature of the market is significant. Large supermarkets have an established loyal customer base with and well-developed logistics. Private label goods became highly desirable, enabling consumers to buy the same products atRead MoreHrm on Tesco3698 Words   |  15 Pages| 2012 | | International and Comparative Human Resource Management Muhammad Rasool | Submitted By : Muhammad Rasool Student ID : L0288SASA1011 Module : International and Comparative Human Resource Management Semester : 6 Submitted To : Rajendra Kumar amp; Tatiana Pavlovsky [TESCO] | | Table of Contents S. No | CONTENTS | Page No. | 1 | Abstract | 3 | 2 | Introduction | 4 | Executive Summary | 3 | Background of theRead MoreTesco Analysis9055 Words   |  37 Pagessimply place your order and receive a non-obligatory quote within 20 minutes. We GUARANTEE that your order will be written by a professional writer with a UK degree, will be plagiarism free, will exactly match your specifications and quality standard, and will be delivered – by your deadline – via email. Strategic Management of TESCO supermarket: PESTLE analysis, Porter s 5 Forces analysis, Critical success factors, SWOT Analysis, VALUE CHAIN analysis, TESCO S strategic options, Core CompetencesRead MoreAn Evaluation of the Business and Financial Performance of Wm Morrison Supermarkets Plc Between 31st January 2005 and 3rd February 20088304 Words   |  34 PagesAN EVALUATION OF THE BUSINESS AND FINANCIAL PERFORMANCE OF WM MORRISON SUPERMARKETS PLC BETWEEN 31ST JANUARY 2005 AND 3RD FEBRUARY 2008 A RESEARCH AND ANALYSIS PROJECT FOR THE B.Sc (HONS) IN APPLIED ACCOUNTING CONTENTS PAGE PART 1 – Project Objectives and Overall Research Approach. 1. Reasons for choosing the project topic 2. Project objectives and research questions 3. An explanation of research approach. PART 2 – Information Gathering and Accounting/ Business techniquesRead MoreCoopers Creek6279 Words   |  26 PagesCase Study Coopers Creek and the New Zealand wine industry Heather Wilson and Maureen Benson-Rea This case describes the growth of a medium-sized New Zealand winery – Coopers Creek. It is concerned with the changing collaborative arrangements employed by Coopers Creek to service domestic and international markets since its inception. These changes are set against the background of a small, rapidly internationalising industry within a global market environment. Readers are encouraged to analyseRead MoreINTERNATIONAL STRATEGY - ASSIGNMENT: Case study: Waitrose2838 Words   |  12 PagesINTERNATIONAL STRTEGY ASSIGNMENT: CASE STUDY: WAITROSE WORD COUNT: 2945 ABSTRACT: This assignment describes focus differentiation strategic models used at Waitrose organisation and its competitive industry. Waitrose environmental is analysed by internal and external factors. Different types of methods have been discussed in this assignment (e.g. PESTEL analysis, SWOT analysis). INTRODUCTION: Waitrose founded in 1904 by Wallace Waite, Arthur Rose and David Taylor. Today its one of the UKs leadingRead MoreConsumer Behavior Towards Big Bazaar15008 Words   |  61 PagesCOMPARATIVE STUDY OF MARKETING STRATEGY REFERENCE TO 4PS OF BIG BAZAR OTHER RETAIL COMPANY Page |1 Management Thesis – 1 | 3rd Semester COMPARATIVE STUDY OF MARKETING STRATEGY REFERENCE TO 4PS OF BIG BAZAR OTHER RETAIL COMPANY CERTIFICATE It is certified that the work contained in the thesis entitled â€Å"A COMPARATIVE STUDY OF MARKETING STRATEGY REFERENCE TO 4PS OF BIG BAZAR AND OTHER RETAIL COMPANY By Rajesh Kumar has been carried out under my supervision and that this work has not beenRead MoreBalanced Score Card for Tesco by Manish4430 Words   |  18 PagesTesco PLC | By manish abraham | This essay presents an analysis of the way in which Tesco implement the balanced scorecard. The strengths and hindrances associated with this approach have also been outlined with respect to this particular case study. The 4 perspectives of the balanced scorecard are examined in detail, the conclusions of which are later divulged. | | | | Table of Contents Introduction – Balance Scorecard page 4 Introduction – Tesco page 6 Financial PerspectiveRead MoreSystem and Operation Management. Critical Evaluation of Relevant Issue. Tesco Case Study4502 Words   |  19 PagesIntroduction The 21st century has brought about several improvements in business strategies and operations. Most businesses have realized that to be very effective in their given industry the internal operations of such businesses have to be to the highest level of standardized efficiency (Wang et al 2010). These busineses have also realized that the effective management of the systems and daily operations of the organisation would facilitate organisational productivity and result in maximizationRead MoreRecruitment and Selection - HRM4324 Words   |  18 PagesSELECTION Introduction Employing the right individual has the potential to, in the long run save the organisation money by reducing turnover. This highlights the importance of recruitment and selection of sales people. Various techniques should be employed to best avoid selecting the wrong individuals for the job. Effective recruitment processes are vital in attracting and retaining high quality staff (Marterel2005). This statement supports the argument that recruitment and selection is the main activity

Man Needs the Environment Free Essays

The environment is the place wherein man lives; it is his dwelling place. Man and the environment has a significant connection which entails that man cannot be detached from it, because his awareness and knowledge about things are both gained from his experiences that take place within his surroundings. Consequently, man tries to settle himself in his environment, both social and physical approaches, in order live life effectively and productively. We will write a custom essay sample on Man Needs the Environment or any similar topic only for you Order Now Man and the social environment. A quality that distinguishes man from other animals is his social nature. Man cannot be compared with other animals because he is placed above and dwells in a habitat where a social interaction is a prerequisite and basic function. â€Å"No man is an island; no man can stand alone. † – This saying implies that man is intrinsically a social being. He cannot detach himself from others and all other creatures in the world; he is intended to be a being-that-exists-with-others-in-the-world. Man has his respective social roles: being-through-others, being-with-others, and being-for-others. These social roles would help an individual establish his social identity. Man is a being-through-others. From man’s conception and birth, he is dependent on other people. He cannot grow up, work, and live neither as efficiently nor effectively, except through others. His life and death will only have meaning when considered in reference to others like him. Also, man is considered as a being-with-others. Despite the efforts to live independently, man cannot and should not live in total isolation rather he should deal and mingle with the people around him. His togetherness towards other creatures characterizes human nature. And in dealing with other individuals, he builds up inter-human relationships. As a result of the social bonds from these relationships, man’s major social needs: attention, affection, and acceptance are being fulfilled. Moreover, with the inter-human relationships he has and the exposure to his environment, his awareness is increased. He will become more conscious and observant of the events and people around him – issues, situations, problems, and conditions. The â€Å"hows† and â€Å"whys† of human actions and interactions will be learned resulting to growth of man’s knowledge. On the contrary, considering that a man who is gifted and is isolated from others since birth; man who doesn’t involve and have social relations ever since, impossibility of man’s survival arouses. In other words, man cannot be said to be a real man only with his biological birth but only when he forms social collective and lives in social relations, will he be able to exist and develop as a man. Man’s personality is moulded and developed within his social environment, through mingling with the people in his surroundings. Through interacting with others, man develops his potentials. Indeed, the social environment itself and one’s exposure to it is vital in one’s life which conveys that man needs it. Man and the physical environment. The physical environment is composed of the natural resources. And from these resources, one’s necessities as a living organism, which includes man, can be acquired. As a living organism, man is in need of water, air, and also of the presence of other living creatures. Man needs air. It is in every living organism’s nature to breathe. Breathing is vital in one’s life. It commonly serves as the basis that an individual has life and is alive. Man needs air to breathe in order to survive. The absence of air in man’s life would suggest and imply that man would eventually die. Also, man needs water. Water is one of the major needs for the survival of every living organism. Water plays an important role in man’s life, and it is involved in man’s daily living. It is used for drinking, for cooking, for hygienic purposes, for tidying things and also for watering the plants. In addition, man needs the presence of other living creatures. The existence of every living organism has an important role in the environment which brings a large impact to the other living creatures in the world. Scientifically speaking, living creatures are said to have and participate in the so called as the Food Web and Food Chain. In these particular concepts, the presence of producers and consumers are considered; plants as producers and animals, which include man, are consumers. With such, man’s survival is dependent on the existence of other living creatures in the environment. And it can be justified through man’s reliance to the gas, oxygen, which can be acquired from the plants, and to man’s practice of considering plants and others animals as his source of food. The presence of every living organism helps maintain the balance of the ecosystem. From the physical environment, man acquires his basic necessities. Indeed, man needs the physical environment for his survival. Man needs both the social environment and physical environment. From these environments, man obtains his needs. And from the satisfaction of his needs, man derives a sense of completeness and in the process, his survival is ensured. How to cite Man Needs the Environment, Papers

Sunday, April 26, 2020

Wireless Technology Essay Example

Wireless Technology Essay It’s a beautiful day in the park, and you are enjoying the sunshine and the company of your friends. Then you remember. You have to do research for your science project. Hey, no problem. Your laptop is right next to you. There in the grass, you are searching the internet for ideas as birds chirp in the background. Wireless technology puts information at your fingertips from practically anywhere in the world. It allows you to connect with friends, family, and others with ease-even if there isn’t a telephone line for miles around. Wireless technology set you free, so you can create a workspace or fun space from practically anywhere. Modern technology has given us easy, convenient ways to transfer information, communicate and entertain ourselves. With wireless technology, we can do all these things on devices that work without wires or cables. Wireless technology includes cell phones, wireless internet connections, and handheld devices such as PDAs, Medical devices such as cardiac pacemakers rely on wireless technology to correct heard rhythms. A global positioning system (GPS) uses satellites and wireless technology to help people know where on earth they are and how to get where they’re going. We will write a custom essay sample on Wireless Technology specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Wireless Technology specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Wireless Technology specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Not long ago, if you wanted privacy for a phone call, you needed a long cord to pull the phone into another room. If you wanted to surf the internet, you had to do it in your home, your office, or on a public computer at the library. Not too long ago you had to stand up and turn a knob on the TV to change the channel. That’s all changed. In the modern times, you can chat with your friends on a wireless Bluetooth handset, send emails on your Blackberry, and download new songs to your Ipod and you can do it all without leaving that sunny spot in the park. What is wireless technology? Wireless technology lets you send and receive information without using wires. It can be said to include simpler, older devices like car radios and baby monitors – even garage door openers and TV remotes. But when we talk about wireless technology, we mean electronic devices that are linked, or networked, together. These devices can send and receive large amounts of information over radio waves. Radio Waves Radio waves are energy waves that move through space at a certain frequency or wavelength. Other kinds of waves travel the same way. These include microwaves, visible light, and X-rays. Different kinds of waves travel at different frequencies. A wave’s frequency is how often it goes up and down in one second. Nearly any information can be transmitted wirelessly, including sounds, text, images and video. To do this you need three basic parts. 1.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   a transmitter 2.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   a receiver 3.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   a carrier wave the transmitter and receiver are electronic devices. They use wires and hardware to function. The carrier wave begins as a continuous wave pattern. But to carry information, it has to be modulated or changed. For example, the sounds in a telephone conversation produce movements called vibrations. These are combined in the transmitter with a constant radio wave, or carrier wave. When they’re combined, the radio wave has been modulated. The two signals travel together through the air. Modulation changes information on the wave into codes a receiver can understand. Wi-fi routers, antennas, and cell phone towers are transmitters. They modulate sounds and images over radio waves. Computers, cell phones and other devices are the receivers. History of wireless communication Electromagnetic waves were first described by a physicist named James Clerk Maxwell. He published a paper in 1864 explaining how light waves and radio waves move through space. At the time, people could communicate by electrical telegraph. Telegraphs send messages over wires, using Morse code. A practical telephone wasn’t invented until 1876. Maxwell’s theory was proven by physicist Heinrich Hertz. In the 1880s, hertz did experiments with a simple transmitter and receiver set apart from each other. When the transmitter produced a spark, the receiver responded with a smaller spark. This experiment showed that electrical energy had traveled across the room wirelessly. Remarkable innovation has been occurring in the wireless category of net centric technologies, facilitated by that hourglass architecture that puts few restrictions on the actual means of transmission. If we can use telephone wires, coaxial cable, or fiber to transmit information using TCP/IP, then why not electromagnetic waves? Despite the obvious disadvantage of tiny screen size, some analysts predict that the cell phone will become the most prevalent means of accessing the internet, outstripping the microcomputer in a short time. In some ways, the mobile internet access market be in the same phase that land-line internet access was in, in 1995, poised on the brink of an explosive growth phase. The internet enabled cell phone may also be in a position similar to the telephone, which was initially conceived as a â€Å"speaking telegraph†. Although PCs abound in industrialized countries, they are far less common in many parts of the world, and certainly more difficult to use and expensive to buy compared to a phone. The cell phone with internet capabilities may be a means to distribute internet access far wider than has been possible in the past. The kind of optimism may have prompted the billions spent by network operators around the world to obtain licenses to run third-generation (3G) wireless netw orks, which involves advantage technology that supports much greater data speeds than the current wireless networks do. Wireless technologies are in a very fragmented state now, with many types of devices on the market using a variety of connection strategies, often incompatible with one another. They can be grouped into three general categories, based largely on the distance the signal needs to travel: personal area, local area and wide area. In the wireless personal area network arena, a key goal is to develop ways for devices to synchronize and interact with one another without short run cables. A technology called Bluetooth is an important ingredient here, and many predicts that it will replace a good portion of the cabling infrastructure that clutters office desks, connecting computers to printers, personal digital assistants, and cell phones. For local area networks, wireless technologies offer another set of attractions, especially for laptop users. Wireless access points can be placed in various locations of a building, and those with laptops and wireless LAN cards can log in to the network from any nearby location. This is becoming very popular for public spaces that would be difficult to configure with data jacks, such as large conference rooms, libraries, airports, and outdoor patios or garden. Office workers can take their laptops to the balcony and enjoy some sunshine as they continue to access the network. Wireless LANs are also becoming popular in homes, particularly for people who have a high-speed internet connection and more than one computer, but don’t want to punch holes in their walls for the wiring. Wire area wireless networks offer many different opportunities for the workplace, including the internet-enabled cell phones and personal digital assistants. Retrieving your email from your PDA while waiting in the line at the airport is not difficult with these devices. The speed of connection is typically slow, but these devices work well for simple text. The â€Å"last mile† has been an obstacle to the delivery of high-speed internet access, especially to remote areas. Wireless wide area networks offer opportunities here as well. It is very expensive to deploy new wiring to every office or residence, but constructing towers with transmitters that can service wider areas is more feasible. Satellites can also be used to serve large geographical areas. In Alaska, for example, satellites are being used to provide Internet connectivity to libraries, schools, and municipalities in remote areas of the state. Wireless systems have been especially vulnerable to intrusion, and they illustrate the tense balance between the desire for openness and the concern for security. For example, employees give rave reviews to the development of the wireless network in which they can use their laptops any place near a corporate access point. Corporations have happily set those points up in cafeterias, in the outside gardens, in the auditoriums, and in the conference rooms to workers from their desktops and make it easy for   people and teams to log in to the network from anyplace on the corporate campus. Yet securing those networks is extraordinarily difficult, and people out in the parking lot or on the street can also access the network with their own laptops. Also â€Å"rogue access points† have been hung without the knowledge of the corporation, thus adding unauthorized â€Å"doors† into the network. Security threats are so common that is easy enough to launch a hoax that frightens people into harming their own computers, under the guise of helping them remove a threat. One such hoax, sent to addresses in the victim’s address book, warned that a virus has been infecting all of them and gave precise instructions on how to remove it. There was no virus, but the file that would be removed if the victim followed the instructions was critical to the computer’s operating systems. Standards As implied earlier, wireless technology are currently being deployed for personal, home, local and wide area networks. Standardization is important in order to support interoperability and reduce costs. Now we look at key WLAN, WPAN, WWAN standards. IEEE 802.11 specifications are focused on the physical layer (PHY) and medium access control (MAC) sublayer of WLANs. The MAC is consistent with the IEEE 802.3 Ethernet standard. The IEEEE standard developed by working group 802.11 was accepted by the IEEE board in 1997 and became IEEE standard 802.11-1997. the standard defines three different WLAN physical implementation (signaling techniques and modulations), MAC function, and a management function. All of the implementations support data rates of 1 Mbps and optionally,   2Mbps. Security, roaming, and QoS are also considered, although major improvements to the security apparatus have been shown to be necessary. The three physical implementations are as follows: 1.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Direct sequence spread spectrum radio (DSSS) in the 2.4Ghz – the most commonly deployed technology 2.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Frequency hopping spread spectrum radio (FHSS) in the 2.4Ghz band 3.  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Infrared light (IR) GPRS is a packet switched wireless data network operations in the GSM environment that enables data to be sent and received using GPRS devices in a more cost efficient and quicker way than was possible over the GSM cellular system. users can secure data download rates up to 53.6 kbps over GPRS compared to 14.4 Kbps via circuit – switched data over GSM. GPRS is a 2.5G wireless technology standard that was expected to improve the data services that can be added to GSM. ETSI defined GPRS in 1997 with the goal of providing packet-mode data services in GSM. GPRS is an over the air system for transmitting data on GSM networks that converts data into standard IP packets, enabling interoperability between the Internet and GSM network. In GPRS a single time slot may be shared by multiple users to transfer packet data. GPRS wireless technology employs authentication and encryption via standard GSM algorithms. One of the key gain from 802.11 standard is the ability for products from different vendors to interoperate with each other. This was not the case with WLAN products available throughout the 1990s. this means that as a user, one can purchase a wireless LAN card from one vendor and a wireless LAN card from another vendor and they can communicate with each other, independent of the brand of access point utilized. This gives the user the choice to choose the system that best meets the needs for each application. As a supplement to the 11-Mbps interoperability testing that will be performed through WECA, a number of vendors have successfully tested interoperability together at the University of New Hampshire Interoperability. Security Considerations for WLANs. IEEE 802.11 provides for security via two mechanisms: authentication and encryption. Authentication is the process by which one station is verified to have authorization to communicate with other stations or APs in a given coverage area. In the infrastructure mode, authentication is established between an AP and each station. Authentication can be either open system or shared key. In the open system, any STA may request authentication. The STA receiving the request may grant authentication to any request or only to those from stations on a user-defined list. In a shared key system, only stations that posse a secret encrypted key can be authenticated. Shared key authentication is available only to systems having the optional encryption capability. Encryption is intended to provide a level of security comparable to that of a wired LAN. Without question, a variety of extremely positive services have been made available to users around the globe with the development and rapid growth of the internet over the last decade. These very useful functions range from communications services, such as instant messaging and telephony, to rapid, real time online transactions, such as e-commerce, internet banking, online gaming, political activism, and online voting. Also, within the past few years, physicians have been able to access over the internet and through handheld wireless devices patients’ health histories and diagnostic records without having to rely on time delaying courier services. Not only have young billionaires have made with the creative development of â€Å"Google-like† search engines, but in addition, government around the globe have made use of the internet to collect homeland security intelligence as a means of keeping their citizens safe.

Wednesday, March 18, 2020

Mass Extinction

Mass Extinction Definition: The term extinction is a familiar concept to most people. It is defined as the complete disappearance of a species when the last of its individuals dies off. Usually, complete extinction of a species takes very long amounts of time and does not happen all at once. However, on a few notable occasions throughout Geologic Time, there have been mass extinctions that totally wiped out the majority of species living during that time period. Every major Era on the Geologic Time Scale ends with a mass extinction. Mass extinctions lead to an increase in the rate of evolution. The few species that manage to survive after a mass extinction event have less competition for food, shelter, and sometimes even mates if they are one of the last individuals of their species still alive. Access to this surplus of resources to meet basic needs can increase breeding and more offspring will survive to pass their genes down to the next generation. Natural selection then can go to work deciding which of those adaptations are favorable and which are outdated. Probably the most recognized mass extinction in the history of the Earth is called the K-T Extinction. This mass extinction event happened between the Cretaceous Period of the Mesozoic Era and the Tertiary Period of the Cenozoic Era. This was the mass extinction that took out the dinosaurs. No one is completely sure how the mass extinction happened, but it is thought to be either meteor strikes or an increase in volcanic activity that blocked out the suns rays from reaching the Earth, thus killing the food sources of the dinosaurs and many other species of that time. Small mammals managed to survive by burrowing deep underground and storing food. As a result, mammals became the dominant species in the Cenozoic Era. The largest mass extinction happened at the end of the Paleozoic Era. The Permian-Triassic mass extinction event saw about 96% of marine life go extinct, along with 70% of terrestrial life. Even insects werent immune to this mass extinction event like many of the others in history. Scientists believe this mass extinction event actually happened in three waves and were caused by a combination of natural disasters including volcanism, an increase of methane gas in the atmosphere, and climate change. Over 98% of all living things recorded from the history of the Earth have gone extinct. The majority of those species were lost during one of the many mass extinction events throughout the history of life on Earth.

Monday, March 2, 2020

How a Solid Propellant Rocket Works

How a Solid Propellant Rocket Works Solid propellant rockets include all of the older firework rockets, however, there are now more advanced fuels, designs, and functions with solid propellants. Solid propellant rockets were invented before liquid-fueled rockets. The solid propellant type began with contributions by scientists Zasiadko, Constantinov, and Congreve. Now in an advanced state, solid propellant rockets remain in widespread use today, including the Space Shuttle dual booster engines and the Delta series booster stages. How a Solid Propellant Functions Surface area is the amount of propellant exposed to interior combustion flames, existing in a direct relationship with thrust. An increase in surface area will increase thrust but will reduce burn-time since the propellant is being consumed at an accelerated rate. The optimal thrust is typically a constant one, which can be achieved by maintaining a constant surface area throughout the burn. Examples of constant surface area grain designs include: end burning, internal-core, and outer-core burning, and internal star core burning. Various shapes are used for the optimization of grain-thrust relationships since some rockets may require an initially high thrust component for takeoff while a lower thrust will suffice its post-launch regressive thrust requirements. Complicated grain core patterns, in controlling the exposed surface area of the rockets fuel, often have parts coated with a non-flammable plastic (such as cellulose acetate). This coat prevents internal combustion flames from igniting that portion of fuel, ignited only later when the burn reaches the fuel directly. Specific Impulse In designing the rockets propellant grain specific impulse must be taken into account since it can be the difference failure (explosion), and a successfully optimized thrust producing rocket. Modern Solid Fueled Rockets Advantages/Disadvantages Once a solid rocket is ignited it will consume the entirety of its fuel, without any option for shutoff or thrust adjustment. The Saturn V moon rocket used nearly 8 million pounds of thrust that would not have been feasible with the use of solid propellant, requiring a high specific impulse liquid propellant.The danger involved in the premixed fuels of monopropellant rockets i.e. sometimes nitroglycerin is an ingredient. One advantage is the ease of storage of solid propellant rockets. Some of these rockets are small missiles such as Honest John and Nike Hercules; others are large ballistic missiles such as Polaris, Sergeant, and Vanguard. Liquid propellants may offer better performance, but the difficulties in propellant storage and handling of liquids near absolute zero (0 degrees Kelvin) has limited their use unable to meet the stringent demands the military requires of its firepower. Liquid fueled rockets were first theorized by Tsiolkozski in his Investigation of Interplanetary Space by Means of Reactive Devices, published in 1896. His idea was realized 27 years later when Robert Goddard launched the first liquid-fueled rocket. Liquid fueled rockets propelled the Russians and Americans deep into the space age with the mighty Energiya SL-17 and Saturn V rockets. The high thrust capacities of these rockets enabled our first travels into space. The giant step for mankind that took place on July 21, 1969, as Armstrong stepped onto the moon, was made possible by the 8 million pounds of thrust of the Saturn V rocket. How a Liquid Propellant Functions Two metal tanks hold the fuel and oxidizer respectively. Due to properties of these two liquids, they are typically loaded into their tanks just prior to launch. The separate tanks are necessary, for many liquid fuels burn upon contact. Upon a set launching sequence two valves open, allowing the liquid to flow down the pipe-work. If these valves simply opened allowing the liquid propellants to flow into the combustion chamber, a weak and unstable thrust rate would occur, so either a pressurized gas feed or a turbopump feed is used. The simpler of the two, the pressurized gas feed, adds a tank of high-pressure gas to the propulsion system. The gas, an unreactive, inert, and light gas (such as helium), is held and regulated, under intense pressure, by a valve/regulator. The second, and often preferred, solution to the fuel transfer problem is a turbopump. A turbopump is the same as a regular pump in function and bypasses a gas-pressurized system by sucking out the propellants and accelerating them into the combustion chamber. The oxidizer and fuel are mixed and ignited inside the combustion chamber and thrust is created. Oxidizers Fuels Advantages/Disadvantages Unfortunately, the last point makes liquid propellant rockets intricate and complex. A real modern liquid bipropellant engine has thousands of piping connections carrying various cooling, fueling, or lubricating fluids. Also, the various sub-parts such as the turbopump or regulator consist of separate vertigo of pipes, wires, control valves, temperature gauges, and support struts. Given the many parts, the chance of one integral function failing is large. As noted before, liquid oxygen is the most commonly used oxidizer, but it too has its drawbacks. To achieve the liquid state of this element, a temperature of -183 degrees Celsius must be obtainedconditions under which oxygen readily evaporates, losing a large sum of oxidizer just while loading. Nitric acid, another powerful oxidizer, contains 76% oxygen, is in its liquid state at STP, and has a high specific gravity―all great advantages. The latter point is a measurement similar to density and as it rises higher so to does the propellants performance. But, nitric acid is hazardous in handling (mixture with water produces a strong acid) and produces harmful by-products in combustion with fuel, thus its use is limited. Developed in the second century BC, by the ancient Chinese, fireworks are the oldest form of rockets and the most simplistic. Originally fireworks had religious purposes but were later adapted for military use during the middle ages in the form of flaming arrows. During the tenth and thirteenth centuries, the Mongols and the Arabs brought the major component of these early rockets to the West: gunpowder. Although the cannon, and gun became the major developments from the eastern introduction of gunpowder, rockets also resulted. These rockets were essentially enlarged fireworks which propelled, further than the longbow or cannon, packages of explosive gunpowder. During the late eighteenth century imperialistic wars, Colonel Congreve developed his famed rockets, which trave range distances of four miles. The rockets red glare (American Anthem) records the usage of rocket warfare, in its early form of military strategy, during the inspirational battle of Fort McHenry. How Fireworks Function A fuse (cotton twine coated with gunpowder) is lit by a match or by a punk (a wooden stick with a coal-like red-glowing tip). This fuse burns rapidly into the core of the rocket where it ignites the gunpowder walls of the interior core. As mentioned before one of the chemicals in gunpowder is potassium nitrate, the most important ingredient. The molecular structure of this chemical, KNO3, contains three atoms of oxygen (O3), one atom of nitrogen (N), and one atom of potassium (K). The three oxygen atoms locked into this molecule provide the air that the fuse and the rocket used to burn the other two ingredients, carbon and sulfur. Thus potassium nitrate oxidizes the chemical reaction by easily releasing its oxygen. This reaction is not spontaneous though, and must be initiated by heat such as the match or punk.

Saturday, February 15, 2020

Supply Chain Management Essay Example | Topics and Well Written Essays - 2750 words

Supply Chain Management - Essay Example Thus, supply network necessitates several levels of integration with the first being the integration of separate components in organizational structures to create individual networks and secondly, integrating the networks. The first level integration results in manufacturing and distribution networks, because individual networks link to a central warehouse that receives stocks from plants when products are manufactured and distributes them to customers through field warehouses. Thus, two networks with the possible routes for manufacturing and distribution form the supply chain network that involve planning, execution and control of components. Managing flow time is crucial in providing effective customer service in the supply chain; therefore, integration is the basis of supply chain management strategy  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Development of efficient MPC system is crucial to the success of all companies that produce goods; since it coordi nates supply chain efforts across company boundaries (Jacobs 1). Inventory is a valuable asset in companies; however, benchmark results indicate that most organizations fail to manage inventory efficiently. Many manufacturers and distributors depend on overly localized inventory policies; thus, companies tie working capital which can result in hurting shareholders. Properly managed inventory acts as a lifeline for supply chain since it propels revenue and competence in companies. In IBM, supply chain inventory practices involve managing flow and positioning of inventory across different stages within the supply chain even in suppliers and downstream partners. The company adopts the opportunity of combining proven supply chain inventory practices, which reduce inventory levels across the organization while improving service levels as well as productivity. The company is does not push back inventory to its suppliers; however, IBM helps its suppliers to reduce their inventory.  Ã‚  Ã ‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Rather than monitor and manage inventory at local level, IBM is increasingly adopting supply chain-wide inventory practices. Companies attempt to decrease amount of inventory in their supply chain management, which in turn reduces inventory carrying costs. The company aims at being responsive and reliable to customers, since it is crucial for the company to increase service levels without increasing inventory investment. Since inventory necessary to attain service levels relates to lead time, reducing lead time as well as supply chain unpredictability is crucial to the company. Moreover, IBM aims at improving financial performance, because it is crucial for the company inventory management success to maximize profit contribution and net margin; thus, reducing distribution and manufacturing costs is essential. In some cases the company institutes lean processes for low inventory; however, it is not too low to drain fina ncial performance of the company, which increases manufacturing re-scheduling and lost sales from uncompetitive flow times. Best companies attain high improvement rate from better inventory management practices, which are augmented when they apply technology to practices like supplier collaboration technology. IBM