Water Pollution Explained

Water pollution is when water contains contaminants. In the context of environmental science, a contaminant is usually a substance which can be harmful to living things like plants or animals. Environmental contaminants can be the result of human activity, for example a by-product of manufacturing. However, they can also occur naturally, like radioactive isotopes, sediment, or animal waste. Because of how general the concept of pollution is, we can assume that polluted waters have been around even before humans were here. For example, a spring might have high sulfur levels, or a stream with a carcass in it would have been unfit for other animals to drink from. However, the number of polluted streams, rivers, and lakes multiplied rapidly as the human population increased, agricultural practices intensified, and industrial development spread. Important Sources of Pollution A number of human activities lead to water pollution harmful to aquatic life, aesthetics, recreation, and human health. The main sources of pollution can be organized in a few categories:   Land use. We have a heavy impact on the land: we cut forests, plow grasslands, build homes, pave roads. Land use activities intercept the water cycle during precipitation events and snowmelt. As water flows over the land and into streams, it picks up anything small enough to be carried away. Vegetation does an important job of holding back organic and mineral components of the soil, but clearing that vegetation means a lot of substances make it into streams, rivers, wetlands, and lakes, where they become contaminants.Impervious surfaces. Most man-made surfaces cannot absorb water like soil and roots would. Rooftops, parking lots, and paved roads allow rain and snowmelt runoff to flow with great speed and volume, picking up along the way heavy metals, oils, road salt, and other contaminants. The pollutants would otherwise have been absorbed by the soil and vegetation, where they would have been naturally broken down. Instead, they concentrate in runoff water, overwhelming the streamsà ¢â‚¬â„¢ capacity to process them.Agriculture. Common agricultural practices, like exposing soils to the elements, using fertilizers and pesticides, and concentrating livestock, routinely contribute to water pollution. Nutrient runoff, mostly phosphorus and nitrates, leads to algae blooms and other problems. Mismanagement of farm soils and livestock can also lead to significant soil erosion. Soil picked up by rain makes its way into streams where it becomes sediment pollution, with harmful consequences on aquatic life.Mining. Mine tailings are the piles of rock discarded after the valuable portion of the ore has been removed. Tailings can leach to surface and ground waters large amounts of contaminants, some occurring naturally in the waste rocks, others a product of the ore processing methods. Mining by-products are sometimes stored in impoundments as a slurry or sludge (for example, coal ash), and failure of the dams holding back these artificial ponds can lead to environmental dis aster. Abandoned coal mines are a notorious source of acid mine drainage: water in flooded mines and in contact with mine tailings sometimes oxidizes sulfur-bearing rocks, and turns extremely acidic.Manufacturing. Industrial activities are a major source of water pollution. In the past, liquid waste was dumped directly into rivers, or put into toxic waste barrels which were then buried somewhere. Those barrels then deteriorated and leaked, resulting in heavily contaminated sites we are still dealing with today. In the United States, regulations now severely limit these practices, notably the 1972 Clean Water Act, the Resource Conservation Recovery Act of 1976, and the Superfund Act of 1980. The release of toxic materials at industrial sites continues, either at levels below regulatory thresholds, or simply illegally. In addition, accidental spills occur all too frequently – for example with the recent West Virginia MCHM spill. In developing countries, pollution from industria l sources is still widespread and dangerous to human and ecosystem health.Energy sector. The extraction and transportation of fossil fuels, notably oil, is prone to spills that can have long lasting effects on aquatic systems. In addition, coal-fired power plants release large amounts of sulfur dioxide and nitrogen oxides in the air. When those contaminants dissolved in rain water and enter waterways, they significantly acidify rivers and lakes. Coal plants also emit mercury, a very toxic heavy metal, polluting lakes throughout the world and making fish unsafe to eat. The production of electricity through hydropower produces much less pollution, but still has some deleterious effects on aquatic ecosystems.Household practices. There are numerous actions we can take every day to prevent water pollution: avoid lawn pesticides, slow rainwater runoff, collect pet waste, properly dispose of household chemicals and medicine, avoid products with microbeads, attend to oil leaks on the mower or car, have the septic tank maintained and inspected.Thrash. A lot of trash persists in the environment, and plastic matter breaks down into harmful microplastics. Are Contaminants Always a Substance? Not always. For example, nuclear power plants use vast amounts of water to cool down the steam generator by the reactor and used to spin the turbines. The warm water is then released back into the river it was pumped from, creating a warm plume that affects downstream aquatic life.

William Moliere s Tartuffe As A Threat Of Reason

The Role of Reason in Religion What happens when hypocrisy invades religion in the absence of reason? This is the very question that Moliere addresses in Tartuffe as he establishes his characters. In satire characters are usually very one dimensional and unchanging. They are simply there to represent an idea. Therefore, rather than using character development, Moliere uses character establishment to shape his story and theme. This is most notably seen in the last two scenes of act one in Tartuffe as he establishes the characters of Orgon, Cleante and Tartuffe. In the establishment of these three characters Moliere forms a strong point about reason’s role in religion and the rightful way to pursue genuine belief. In the last scenes of act one in Tartuffe Orgon’s character is established by his attitude towards his family, his misplaced concern for Tartuffe and his blindness towards Tartuffe’s hypocrisy. As Orgon makes his entrance into the story, he inquires of his brother-in-law that state of his estate. Dorine reveals that the lady of the house has been very sick even going as far to say that a bleeding â€Å"has saved her from the grave.† Orgon takes the information in without acknowledging it. His only concern is for Tartuffe, the religious man he has taken in and aspires to be like. This nonchalant attitude toward his family reveals disconnect between him and his family that is only made up for in his relationship to Tartuffe. This replacement of a practical stranger for

Brain Compatible Strategies Free Essays

One of the most important avenues of debate when it comes to education is the question on how to make the learning experience in school be also connected with real life. There are many hurdles to answering this question. For example, the feeling of being closed in during learning makes the students feel that school is an entirely different world and is an entirely different experience, and when classes and end and they rejoin the real world, they tend to leave the things that they relate to school in the recesses of their mind and shifts their cognition by turning on the brain they use for real life. We will write a custom essay sample on Brain Compatible Strategies or any similar topic only for you Order Now This is just one of the many different factors, and because of this reason, experts are consistently looking for a way to ensure that what the children learn is something that they also apply in real life. The effective designing, formulation and use of brain compatible strategies are important in the learning experience of the students; but more importantly, the brain compatible strategies should also be updated and up to date. As Sousa (2003) explained, â€Å"the sit-down-be-quiet-and-listen model is not compatible with the brains of many students who now cross the thresholds of our schools because the environment has affected the contemporary student brain compared with that of just 20 years ago (Sousa, 2003, p. 101). † The use of brain compatible strategies are strategies which do not just help in the effective teaching and lesson retention inside the classroom; more than that, the application of these approaches of this type of style is also usually connected with approaches that individuals take in real life when they are faced with different scenarios, picking a system which the individual feels is suitable for a particular situation. Because of this, brain compatible strategies help not just in the learning process of school-based education but also close the gap found between school life and real life. According to Karten (2007), one of the basic principles of brain-based learning strategy is the use and the presence of the effect of â€Å"activities such as simulations and role (that) provide real-life emotional connections (Karten, 2007, p. 57). † This is one of the proofs that through the use of brain compatible strategies in teaching and in the learning experience of children, the lessons learned are applied in real life, closing the gap found between school life and real life. What is the gap between school life and real life? For some students, the problem with going to school is that they see lessons in school as purely limited for use inside the school or inside formalistic educational grounds. They see math solutions as tools to achieve problems inside the classroom as well as history notes as the key to answer the midterm history exam. The manner by which the students are thought sans brain compatible strategies isolate school life and real life, and when this happens, the students feel that whatever it is they learn in school is exclusive for school use alone, which should not be the case because the lessons learned in school should be transformed as intellectual tools that should be used in real life so that a person can react correctly and rationally in real life situation. This is the gap present in school life and real life, and there was a point that the gap grew bigger and bigger simply because of the fact that the teaching style does not make the learning experience of the students a way for them to realize that what they learn in school should be applied in real life – that math solutions should be applied for counting changes when buying in a store, that the critical thinking during science experiments should be extended in real life. Take for example the different types of brain compatible strategies being used today. In cooperative learning, the student is learning school based education while at the same time learning the value and use of cooperation between individuals, and because of that, the student transfers this knowledge about cooperation in real life. The same is true with the use of problem-solving, which infuses in the child’s conscious and unconscious mind the need to use critical thinking not just to solve school examinations but real life problems as well (Cooperative Learning, Collaboration, Problem-Solving etc. ), not only increase student learning but also help bridge the gap between school and â€Å"real life. † Experts are inclined also to believe that as much as most people believe that brain compatible strategies for learning should impact not just school-based scenarios but real life as well, the truth is that proponents of brain compatible strategies who teaches this system to teachers are advocating the use of not just school-based examples but also to use real life examples to teach the students how the lessons in school are actually usable as well in real life scenarios and not just limited to school experience. As Tate (2006) explained in her book about integrating brain compatible system in teaching inside the classroom, â€Å"a third way to gain student’s attention is to connect the learning to real life. It stands to reason that if the brain was meant to survive in the real world, then the closer a teacher can get the instruction to the real world, the more memorable it becomes (Tate, 2006, p. 51). † Conclusion – The use of brain compatible strategies to teach students today has already garnered many followers, if not something that is already widespread, and people ask why such phenomena occurred. Brain compatible strategies are always changing, based on the changes happening on the target audience, and it is important that everyone is on the same page. Maybe the shift in the education paradigm has happened. Before when education was limited to a select few, the idea was to teach things that cannot be easily learned by sheer experience alone (i. e. technique in arts, formula in sciences, strategies in politics), but now educators are looking the reality that what the students needs is a good dose of traditional educational content and lessons which have practical application to assist in the refinement of the actions and reactions individuals make when faced with circumstances, using the knowledge transmitted and embedded in a child’s brain through the use of brain compatible strategies that closes the gap between school learning and real life learning. References Fisher, Robert (December 2005). Teaching Children to Think. Thornes Nelson. Karten, Toby J. (April 2007). More Inclusion Strategies That Work! : Aligning Student Strengths with Standards. SAGE Publications. Sousa, David A. (May 2003). The Leadership Brain: How to Lead Today’s Schools More Effectively. SAGE Publications. Tate, Marcia L. (August 2006). Shouting Won’t Grow Dendrites: 20 Techniques for Managing a Brain-Compatible Classroom. SAGE Publications. Tracy, Kim (May 2000). Brain Compatible Learning: Another New Program†¦ or Is It?. The Teachers. Net Gazette. Volume 1 Number 3. Retrieved June 14, 2008, from http://teachers. net/gazette/MAY00/bcl. html How to cite Brain Compatible Strategies, Papers

Micheal Jackson free essay sample

There are 2 approaches to do this: ) the real speech- this Is the description of a real, tangible, and physical that Is so vivid and precise that the audience can picture It In their mind. The subject could be a place, an object, a person, etc and is described so clearly that the audience can accurately visualize it. B) The mood speech- this is where you attempt to convey Just how a particular emotion or feeling feels; and the successful mood speech has the audience actually experiencing that emotional state. For instance, when answering the question How does It feel when you are depressed? The speaker does not simply sit other synonymous labels for depression such as down, bummed, low, but focuses Instead upon the physiological ( weak, listless), mental (slower thinking, confusion), psychological( joyless, hating self), social( rejected, friendless) aspects. A good contemporary example is the TV ad about ADD that likens this condition to trying to watch TV with the channels changing every second while showing a rapidly changing TV in the background. We will write a custom essay sample on Micheal Jackson or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Mood speeches are difficult to maintain and develop as the entire speech, and are used many times as a segment of a report speech on hat topic. ) Report the Report speech is a vastly different speech from the mood speech in that it deals with hard facts and precise data in a very analytical way. It also can be used in a myriad of ways: the life cycle of a flea, a biography of a person, a report giving information about a culture, country, religion, event, medical condition, etc. Even topics of some controversy can be Informative In this category: compare/ contrast prescription generic drugs, the legal history of Roe v. Wade, pros/cons of legalizing prostitution/pot/gambling: school uniforms.The over-riding goal here is to remain fair and objective, the audience should not be able to tell what the speakers personal position on the topic happens to be. It is unethical to hide a persuasive agenda under the auspices of an Informative speech, so avoid l want to inform you why prostitution should be legal and/or So you can see that since the pros greatly cons) without fairly and honestly including the cons (or pros). 3) Explanation- the speech of Explanation defines a process. This is NOT a how to speech; it explains how and/or why some process occurs.This is very much like a tour guide at the mint telling their group how coins are made. This is a more intellectual approach to a process- how diamonds are formed, how the AIDS virus invades T-helper cells, how wood becomes petrified, the water cycle, photosynthesis, how microwaves cook food, any surgical procedure, how the brain stores memories, how viruses infect computers, what makes a survivable curve- the list is endless. Think of all the processes you understand, any of them have the potential to be a good explanation speech. Instruction this IS the traditional How to speech, and this is where the process is actually performed, or we are taught how to do it. This has a hands-on feel to it: how to write a good resume, how to save money/gas/time, how to pack for a vacation, how to debug your computer, how to throw a survivable. Sometimes the process can easily be demonstrated within the time limits of a speech; other processes my take longer than the allotted time. If that is the case, then have the successive steps/ stages pre-done so you can move easily form one to the next.The audience really doesnt need to watch you slice six carrots for a salad instead have all of them pre- sliced and Just demonstrate a few cuts and then move on, nor do we need to wait until the paint dries. Take a hint from the professionals that do the hobby/craft/ cooking shows on TV, a bit of careful planning beforehand can result in a polished presentation of even a very complex process. These are the categories of Informative Speaking. You do not have to stay within Just one type, they can be combined as you see fit.For example, in speech that is primarily Explanation, there may be a section where you need to Describe what something looks like and there may be some elements of Report if you discuss the history of it. There is an easy way to consolidate the points of the text with these 4 types of informative speeches. Think of the categories listed in the text as general topic areas from which an Informative Speech topic could be found. Once a topic has been selected, then its development can be guided and focused by the 4 types of informative speeches.

The Suppliants monologue Essay Example For Students

The Suppliants monologue Essay A monologue from the play by Euripides NOTE: This monologue is reprinted from The Plays of Euripides in English, vol. ii. Trans. Shelley Dean Milman. London: J.M. Dent Sons, 1922. IPHIS: Why was this privilege, alas! denied To mortals, twice to flourish in the bloom Of youth, and for a second time grow old? For in our houses, we, if aught is found To have been ill contrived, amend the fault Which our maturer judgment hath descried; While each important error in our life Admits of no reform: but if with youth And ripe old age we twice had been indulged, Each devious step that marked our first career We in our second might set right. For children, Seeing that others had them, much I wished, And pined away with vehement desire; But if I had already felt these pangs, And from my own experience learnt how great Is the calamity to a fond father To be bereft of all his hopeful race, I into such distress had never fallen As now o\erwhelms me, who begot a youth Distinguished by his courage, and of him Am no deprived. No more. But what remains For mewretch that I am? Shall I return To my own home, view many houses left Without inhabitants, and waste the dregs Of life in hopeless anguish, or repair To the abode of Capaneus, with joy By me frequented while my daughter lived? But she is now no more, who loved to kiss My furrowed cheeks and stroked this hoary head. Nought can delight us more than the attention Which to her aged sire a daughter pays: Though our male progeny have souls endued With courage far superior, yet less gently Do they these soothing offices perform. Will ye not quickly drag me to my home, And in some dungeon\s gloomy hold confine, To wear away these aged limbs by famine? Me, what, alas! can it avail to touch My daughter\s bones! What hatred do I bear To thee, O irresistible old age! Them, too, my soul abhors who vainly strive To lengthen out our little span of life; By th\ easy vehicle, the downy couch, And by the boasted aid of magic song, Labouring to turn aside from his career Remorseless death: when they who have no longer The strength required to serve their native land Should vanish, and to younger men give place. We will write a custom essay on The Suppliants monologue specifically for you for only $16.38 $13.9/page Order now

The eNotes Blog Some Take-Aways from Twitters FictionFestival

Some Take-Aways from Twitters FictionFestival As promised in last weeks post on Twitters Fiction Festival, heres a round up of a few standouts of the online event, which finished this past Sunday. Four things I took away from the festival, besides learning how to read from the ground up: 1. My personal favorite was Andrew Pypers sinister adaptation of Thomas Hardys classic horror novel The Turn of the Screw. Only downside, should blare a massive SPOILER ALERT banner at the top of the account page. Do not ruin this story for yourself by reading the first few tweets! Scroll straight to the bottom of White House, which you can read in full  here. #socreepy 2. Another fantastic creative endeavor was writer Lucy Coats retelling of 100 myths in 100 tweets. Check out this pithy (and alliterative) summary of Odysseus encounter with the sirens, below: You can find a collection of many more of her mythical re-imaginings, including the tales of Leda and the Swan and Heracles, at her twitter account here. #pervyancientgreeks 3. Elliott Holts mystery tale had an interesting twist to it. The story was made up of tweets from a crowd of partygoers, unambiguous as to whether what they witnessed was a suicide, an accident, or murder. The multiple voices create an interesting, interwoven narration. Plus the self-centeredness and banality with which these characters tweet spins an interesting satire on the way we present our lives online for others amusement and approval. I think. Scroll down Holts twitter page to read this very interesting and suspenseful form of the classic murder mystery. #likecluebutbetter 4. Twit-Lit-Crit: so now that we have twitterature changing the form of storytelling, will literary criticism follow in the same vein? Carmel Doohan of Exeunt Magazine conveyed a critique of the weekend via a series of tweets, just like the authors had done themselves: Essentially a blank page where any text or format can be uploaded,  @storify  makes a bricolage of social media. On it the twitter fiction works, but when encountered on twitter itself it is frustrating; interruptions and RTs spoil the flow Yet there is something very modernist about it- interruptions incorporated into the fiction; remaining true to the fragmentation of reality Even the Guardian jumped into the fray, doling out self-effacing reviews in under 140 characters. It makes me wonder, like Doohan asks, will the twitter essay forever change the face of  criticism? Answers on a postcard. Did you have time to check out the Twitter Fiction Festival? If so, what were your take-aways?

Parimary Article Summary Assignment Example | Topics and Well Written Essays - 250 words

Parimary Article Summary - Assignment Example She asserted that in order to achieve success in the implementation and execution of the goals of TCN, it is essential that efforts are directed based on qualitative research, which can guide the future directions of the TCN paradigm. Doing this will ensure delivery of quality nursing care and resolution of diverse ethical issues, which are desired to achieve TCN goals. The nurses should be educated with a mindset of planning appropriate policies and understanding the cultures of different communities and how they are circuitously connected with the concept of care. This practice will help the nurses to educate the future generations and students about TCN. The foreseeable development towards TCN will surely help the world as a whole. The teaching of nurses on all possible levels of all cultures will help this multi-cultural world become a better place. To achieve success, it is necessary to develop the right strategies, training procedures, and education policies for nurses. TCN is still in progress and needs much hard work and dedication. Nonetheless, the theory of TCN and the efforts behind it are

Writing journal for the chapter Assignment Example | Topics and Well Written Essays - 1000 words - 1

Writing journal for the chapter - Assignment Example "By this sound-change, an ae and e in early Old English was changed to a diphthong (ea and ie respectively) when preceded by certain palatal consonants (c, g, sc)" (Baugh & Cable 72). Celtic transmission - Celtic transmission refers to the transmission of Latin words into Old English through the association of Celts with the English. The Celts had adopted a considerable number of Latin words but very few words were adopted by the Anglo-Saxons who did not share a harmonious relationship with the Celts. (Baugh & Cable 74) modus vivendi : The literal meaning of the term modus vivendi is "manner of living". However, it is used to describe a working arrangement that disputing parties can live with, at least until a more permanent solution can be found (Cornog 58). While discussing the amalgamation of the Scandinavians with the old English, Baugh & Cable introduce the term "modus vivendi" to describe the policy followed by the English kings to reestablish their power in Danelaw. Discussing the relationship between the Celtics and the Anglo-Saxons, the author mentions that "In parts of the island, contact between the two peoples must have been constant and in some districts intimate for several generations" (Baugh & Cable 69). Even then it is found that "outside of place-names, however, the influence of Celtic upon the English language is almost negligible" (Baugh & Cable 69). It is this that made me wonder why the Celtic place names were retained and words from other spheres of life abjured. 2. The author mentions that " It is altogether likely that many Celts were held as slaves by the conquerors and that many of the Anglo-Saxons chose Celtic mates." Given that not many words were adopted by the Anglo-Saxons, What was the language of communication between the two communities? 3. Why were words like noun "cook" and general word "plant" were adopted from the Latin? These general words might have been present in Old English given that they are

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

Cloning - Research Paper Example Cloning has now been the edge of modern medical science for a few decades now. The initial success that leading cloning experts and researchers had with the creation of a cloned sheep Dolly initiated the enthusiastic pursuit of this controversial discipline that has far-reaching impacts on the biology of mankind, life and the society at large as well. The scientific term, â€Å"Cloning† is the replication of an organism such that its genetic makeup is the same and as a result it appears as a carbon copy of its original counterpart. Clones have the same physiology, external appearance and the same genetic coding within their cells. In layman’s terms it is an exact copy of a particular organism.( Mediline Plus, 2012, p.1) So far the Cloning project and several genome projects have achieved success in cloning simpler organisms like micro-organisms, rats and the latest sensational breakthrough of Sheep cloning by bringing into the earth the first complex organism under the mammal species, a sheep nicknamed: Dolly. However Cloning has several risks and the current stage of knowledge and research is inadequate to successfully copy human genome and create an exact carbon copy. Lower level organisms too displayed extreme susceptibility to diseases, a very poor internal defence mechanism and intruder detection system and fragility in day to day course of existence. The Sheep ‘Dolly’ couldn’t be kept alive for long, surviving only for a short span of 6 years, dying due to progressive ling disease. Cloning: Change in Parenthood and Biological Origin The process of cloning involves a total paradigm shift, a total societal change in the way organisms reproduce sexually giving birth to a child with equal chromosomes being contributed by either partner. Cloning of Dolly was done with the help of three participating organisms. The first participant was the sheep that donated its somatic cell and gene from its mammary gland, the second sheep do nated the egg and the third sheep was used to bear the embryo to term. The process of cloning is inspired and based on the natural process of embryo multiplication wherein an egg after fertilisation divides into two thus bringing into existence two identical twins. The sperm cell punctures through the egg followed by fertilisation and separation of a portion of the egg to give rise to an identical embryo at a later stage of fertilisation. (The University of Utah., 2012, p1.) Cloning replicates this process almost mechanically, aping the natural process step by step in cooking up a clone, through artificial embryonic multiplication, gene implantation, extraction and gestation in a mother’s womb until birth. Somatic Cell Nuclear Transfer The process of Cloning involves the SCNT, Somatic Cell Nuclear Transfer. Somatic Cells refer to cells in the body other than the two types: egg and sperm cell. Egg cells and Sperm cells have one set of chromosomes whereas somatic cells have a c omplete set of chromosomes inherited form its biological parents. (National Human Genome Research Institute, 2012, p1.). The cloning process involved three stages: somatic cell sourcing, nucleus extraction form the somatic cell of the adult sheep (intended sheep to be cloned) and finally implantation into a female sheep’s womb for successful gestation to term. Dolly the sheep was cloned in the same process. The fundamentals of cloning technology were applied. A somatic cell was taken from an adult cell’s mammary glands, the nucleus was extracted from the cell of the adult female sheep (source of clone) and the implanted in an embryo of another sheep. Soon the embryo started behaving normally and showing signs of acceptance of the nucleus. This embryo was later implanted into another female sheep for rearing in the womb until term and delivery. (Stanford Encyclopaedia of Philosophy, 2008, p1.) Risks of Cloning Reproductive cloning is extremely expensive and has high fai lure rates. Almost 90 % of all cloning attempts fail to produce

Series Pass Voltage Regulator From Discrete Electronic Engineering Essay

Series Pass Voltage Regulator From Discrete Electronic Engineering Essay The objective of this project was to construct and design a 9V  ± 0.3V, 1A series pass voltage regulator from discrete electronic parts. The voltage regulator must exhibit a voltage regulation of 5% or better and should be supplied with a dc input voltage. The regulator circuit was required to include a way to disconnect the load from the regulator if the load current exceeded 1A or if the temperature of the series pass element exceeded 40 °C. It was necessary to measure each parameter of the circuit and convert it from an analog to a digital signal. This signal would provide data necessary to display the values on the Spartan III FPGA Development Board. The numerical display was not to have any zeros leading a number, unless it affected the value. Also, the display was to be cyclic, alternating at 5 second intervals. The circuit was designed, built and tested. It produced 9.03V output and 1.02A through a 9à ¢Ã¢â‚¬Å¾Ã‚ ¦ load. The cut-off protection worked as well as the variable sensing circuitry. The linkage of the analog and the digital components, however, remain incomplete. Contents LIST OF FIGURES LIST OF TABLES LIST OF ABBREVIATIONS AND SYMBOLS Symbol Description ADC Analog to Digital Converter Op-amp Operational Amplifier V Voltage/Volts I Current R Resistance A Ampere à ¢Ã¢â‚¬Å¾Ã‚ ¦ Ohm  °C Degree Celsius F Farad IC Collector Current IB Base Current VBE Base-Emitter Voltage LUT Look Up Table BCD Binary Coded Decimal MUX Multiplexer CLK Clock DPDT Double Pole Double Throw FPGA Field Programmable Gate Array Table : List of Abbreviations Contained in this Report INTRODUCTION Commercial power is usually distributed with an AC supply. An unregulated voltage such as this could cause damage to many household appliances and electronic devices. Therefore it is a safety hazard. A voltage regulator is a device that maintains a relatively constant output voltage for a varied input voltage. It functions by comparing the output voltage to a fixed reference and minimizing this difference with a negative feedback loop. The aim of this project to design a series pass voltage regulator with an output of 9  ± 0.3V and regulation of at least 5%. It should be able to disconnect the load from the regulator for temperatures exceeding 40à ¢Ã‚ Ã‚ °C and a current greater than 1A. Using A/D converters, these values (output regulator voltage and current, temperature of the series pass transistor) were converted to digital format and displayed on the Spartan III FPGA Development Board. Each value received from the analog component should be displayed with no unnecessary leading zeroes. The display had to alternate between different variables of voltage, current and temperature. The Digital Component of this project was designed in Xilinx ISE 7.1i, and the necessary tests were carried out. A User Constraints file was created, which allowed for the programming of the FPGA Board. BACKGROUND THEORY AND LITERATURE REVIEW Using an unregulated power supply is unfeasible for most tasks. This is because as the load current increases, the ripple voltage increases and the DC output voltage decreases. The voltage regulator greatly reduces ripple and produces a steady output voltage for a range of input voltages. Different types of voltage regulators have different functions. There are two main types, shunt and series voltage regulators. Shunt Voltage Regulator For a shunt voltage regulator, the regulating device is placed in parallel with the load. A resistor is placed in series with the load and the unregulated supply. The current is varied through the control element depending on the load current. This causes a voltage drop across the resistor in series, maintaining a constant load voltage. (Prof. Gift, 2012) Figure : Shunt Voltage Regulator Shunt Voltage Regulator Example: Zener Diode Regulator Figure : Zener Diode Voltage Regulator The zener diode is a semi-conductor diode designed to operate in the reverse-biased region. In forward bias, it functions as a normal diode but when in reverse bias, it breaks down for voltages exceeding the breakdown voltage, or zener voltage. For operation in this region a current Iz is required where the limits being the minimum and maximum current for the diode to operate without breaking down. (Prof. Gift, 2012) Series Voltage Regulator For a series voltage regulator, the regulating device is placed in series with the load and the unregulated supply. (Prof. Gift, 2012) The output voltage is sampled by a circuit that provides a feedback voltage to be compared to a reference voltage. If the output voltage increases, the comparator circuit provides a control signal to cause the series control element to decrease the amount of the output voltage, thereby maintaining the output voltage. If the output voltage decreases, the comparator circuit provides a control signal to cause the series control element to increase the amount of the output voltage. (Electronic Devices and Circuit Theory 7th Ed.) Figure : Series Voltage Regulator There are different circuit topologies for the series voltage regulator. These will be examined next. Simple Series Transistor Regulator To improve the current capacity of the zener diode regulator, a transistor is used in the emitter follower configuration. This acts as the series control element. The collector is supplied by the regulated voltage. The transistor reduces the load current capacity of the zener by a factor of the transistor current gain. The zener voltage is therefore produced at the emitter. The equation IC = ÃŽÂ ²IB is used to link the collector current and the base current. Due to high current gain, even very large changes in IC result in only small changes in IB. This means IZ is mostly stable. The input voltage must be greater than the diode voltage to ensued proper transistor bias. (Prof. Gift, 2012) Figure : Simple Series Transistor Voltage Regulator IZ current through the zener diode IC collector current IB base current Discrete Voltage Regulator A transistor Tr2 is connected as the series pass transistor and another one Tr1 acts as the error amplifier. In the single transistor regulator output ripple voltage is low, but the output voltage still varies. This is due to the VBE/IC characteristic of the transistor. Feedback is used to correct the output. This amplifier compares the sampled voltage with a reference voltage in order to generate a signal proportional to the difference. This is used to drive the series pass element, which then varies the output voltage such that the error is reduced and the output voltage regulated. Figure : Discrete Transistor Voltage Regulator The voltage across the series element is (Vin Vout). The input voltage to the error amplifier is ÃŽÂ ²Vout Vref, where . The output voltage across the series element is an amplified version of the input voltage, . If Vref is constant, . This is the stability factor. This means that the ripple voltage is reduced by a factor of . The higher the loop gain, AÃŽÂ ², the better the regulator performance. A is gain of error amplifier. The resistor R can be connected to the regulated side of the circuit to improve the design and decrease ripple voltage. Also, a capacitor may be placed in parallel to the Zener diode. Another capacitor can be placed across the output removing output noise and input impedance at high frequencies. A Darlington Pair may be used as the series element. This has two transistors in a single package. The Darlington Pair increases the current gain of the series element, making it able to supply a larger load current if required. (Prof. Gift, 2012) Operational Amplifier Series Voltage Regulator In order to improve the regulator performance, the loop gain A is increased. A simple method of doing this is to replace the transistor error amplifier with an operational amplifier as shown in figure 6. The operational amplifier compares the reference voltage of the zener with the feedback voltage sampled by resistors R1 and R2. The Darlington Pair design is used here and R3 connected to the regulated supply to reduce the ripple voltage. The operational amplifier (op amp) must be supplied by the unregulated input voltage. (Prof. Gift, 2012) Figure : Operational Amplifier Series Voltage Regulator STANDARDS Certain standards were considered in the undertaking of this project. These are: ISO 9001:1994 Quality Systems Model for Quality Assurance in Design, Development, Production, Installation and Servicing (http://www.ttbs.org.tt/) TTS 620 2008 Occupational Safety and Health Risk Assessment Requirements(http://www.ttbs.org.tt/) BS QC 790304:1994 Specification for harmonized system of quality assessment for electronic components. (http://www.standardsuk.com) RISK ASSESSMENT Possible Hazards: 15V supply voltage. Risk of electrical shock, burns and death. Solder fumes present. Dangerous if inhaled. The heat generated by the power resistor could cause burns. The tip of the soldering gets very hot and could cause severe burns or start a fire. Clipping wires and leads may cause them to be projected into eyes and face. Steps Taken to Avoid Risk: Ensured that student was properly grounded. Proper clothing and footwear were worn. No long hanging jewellery or hair. Before energising a circuit, it was checked by a technician. Tested conductors before handling them. Exhaust fan present in lab. Regularly stepped outside for fresh air. Clipped wires away from face of anyone present. DESIGN APPROACH AND METHODOLOGY Project Requirements: Design and build a 9V  ± 0.3V, 1A Series Pass Voltage Regulator using discrete electronic components. Regulator must have a voltage regulation or 5% or better and must be fed by a dc input voltage from a laboratory power supply. In addition, the regulator must incorporate temperature and over current sensing circuits which would disconnect the load from the regulator, for temperatures and currents exceeding 40 degrees centigrade and 1 A respectively. The output regulator voltage and current, together with the temperature of the series pass transistor must be converted to digital format using A/D converters and displayed on the Spartan 111 FPGA Development Board when selected. The following specifications must be met for the display of the variables: 1. The units of all variables are to be displayed along with the respective reading. 2. The voltage is to be displayed to 1 decimal point. 3. The current is to be displayed to 2 decimal points. 4. The temperature is to be displayed as a whole number. 5. The display of the readings for voltage, current and temperature are to automatically appear in a cyclic manner, with each reading being displayed for 5 seconds. 6. All leading zeros are to be suppressed. (ECNG 2004 Design Project Description) This design had both an analog and a digital component. ANALOG COMPONENT This component involved the design and construction of the Series Pass Voltage Regulator and the sensing circuitry to detect current, voltage and temperature. These sensors were constructed to relay the values necessary for the digital component. Analog to Digital Converters were designed to convert the analog output from the current, voltage and temperature sensing circuits to digital format so as to be to be read by the Spartan FPGA Board. Design of the Operational Amplifier Series Voltage Regulator Figure : Circuit Diagram of the Operational Amplifier Series Voltage Regulator The regulator was powered by a DC input voltage from a laboratory power supply. The voltage used in the design process for the purpose of calculation was 15 volts. Choosing the Zener Voltage and Zener Current The Zener Voltage, Vz was supplied by the Zener Diode, D1 as shown in Figure 7 above. The Zener Voltage was used as a reference voltage by the Operational Amplifier. The op amp is functioning as a differential amplifier in this situation. The difference between the inputs at the inverting and non-inverting terminals is amplified. Gain, The output voltage, VZ zener voltage Vz should be high enough so that gain would not decrease to achieve the required output. If Vz was too high, i.e. the output voltage, no current would flow through D1. An appropriate value between 0V and 9V was chosen, VZ = 4.8V. The IN4732 Zener Diode was chosen and the specification sheet for this model was obtained. The specified test current was 53mA, and the chosen value was 40mA. This was chosen to ensure proper bias. Calculating Resistor R3 The resistor R3 was in series with the Zener Diode. Therefore, the current through them is the same. A 100 à ¢Ã¢â‚¬Å¾Ã‚ ¦ resistor was chosen as it was the closest one in value available in stores. R3 = 100à ¢Ã¢â‚¬Å¾Ã‚ ¦ Calculating Resistors R1 and R2 Resistors R1 and R2 formed a potential divider providing the inverting input of the op amp. This sampled the output and sent it to the error amplifier. If the value of the output changed from the designed, the voltage drop across the resistors would change and the op amp input voltage would change, producing an error voltage at the output of the op amp. This error voltage will either turn on more or turn off more Transistor Tr1 and effectively Tr2 as well. The output voltage, Vo is related to the Zener Voltage by the equation below. Substituting Vo = 9V and Vz = 4.8V, Therefore, If R2 chosen to be 10kà ¢Ã¢â‚¬Å¾Ã‚ ¦, then Therefore, R1 = 8.8kà ¢Ã¢â‚¬Å¾Ã‚ ¦ and R2 = 10kà ¢Ã¢â‚¬Å¾Ã‚ ¦. Choosing an Operational Amplifier The LF351 op-amp was chosen for this design. It only needed to function as a differential amplifier. Choosing the Series Pass Transistor The required output current was 1 Ampere. Therefore the maximum collector current of the series pass transistor had to be greater than 1 A. high power transistor was needed, but the current gain of power amplifiers is low (approximately 40). The base current and collector current for a transistor are related by the following expression. Substituting Current gain, hfe = 40 and Ic = 1 A, The LF351 op amp could not supply this base current. A Darlington Pair arrangement was used instead. Darlington Pairs have high current gain. The high power transistor chosen was TIP31C, packaged in a TO-220 Case. The current gain, hfe1 of this transistor was specified to be between 10 and 50, so a value of 30 was used. An NPN medium power transistor, BFY51 in a TO-39 metal package, was chosen for Tr2 in Figure 6. The current gain, hfe2 was found to be 123. Hence, total current gain of the Darlington Pair: hfe1 ÃÆ'- hfe2, i.e. 30 ÃÆ'- 123 = 3690. Substituting Current gain, hfetotal = 3690 and Ic = 1 A, Design of the Voltage Sensing Circuit The purpose of the Voltage Sensing Circuit was to determine the output voltage of the regulator and relay this voltage to the Analog to Digital Converter input. The Analog to Digital Converter (ADC) chip (ADC08040 IC) had a reference voltage of 4.5V. The maximum voltage possible was 9.5V. Hence if the voltage output was 9.5V, the ADC08040 input voltage should be 4.5V. VO had to be stepped down by a potential divider before it could be sent to the ADC08040. It was stepped down by a factor of . Let R1 = 1kà ¢Ã¢â‚¬Å¾Ã‚ ¦, then R2 = 1kà ¢Ã¢â‚¬Å¾Ã‚ ¦ This voltage was sent to a Unity Gain Voltage Follower (Figure 8) and was input to the ADC circuit. (Prof. Gift, 2012) Voltage Sensor.bmp Figure : Voltage Sensing Circuit Design of the Current Protection Circuit The purpose of this was to disconnect the load from the regulator when the current flowing through the load surpassed 1A. The protection circuit monitored the load current and sent a signal to a device to disconnect the load, when the current rose to over 1A. A 1à ¢Ã¢â‚¬Å¾Ã‚ ¦ shunt was used in series with the 9à ¢Ã¢â‚¬Å¾Ã‚ ¦ load resistor. The shunt voltage was used to determine cut-off. An instrumentation amplifier was chosen (INA114AP) to compare the temperature sensor voltage and a potential divider voltage. The shunt voltage was amplified to increase chances of accurate determination of when to disconnect the load. A potential divider was constructed to deliver a4V, and the shunt voltage was also amplified to 4V. Potential Divider: Which gives: Let R1 = 20kà ¢Ã¢â‚¬Å¾Ã‚ ¦ The voltage from the shunt was amplified to 4V as well, and this was done by an op-amp and two resistors set up in the non-inverting amplification configuration shown below. The reference used to be amplified was 0.9V from the shunt, as this was the value which, if exceeded, cut-off and disconnection of the load was supposed to occur. For an non inverting amplifier, Vo = 4V, Vi = 0.4V, And Let R1 = 2.4kà ¢Ã¢â‚¬Å¾Ã‚ ¦, R2 = 8.2kà ¢Ã¢â‚¬Å¾Ã‚ ¦ .Temperature Amp Input to INA.bmp Figure : Circuit for Comparison and Determination of Cut-off When both inputs have the same voltage across them, the instrumentation amplifier would have an output of zero. The transistor in Figure 10 would be turned off and the base would be at 0V. The transistor used was a 2N3904 (Ic = 200mA). If the output is non-zero, the base would be driven by a voltage and the transistor will be ON. When the output is zero (same inputs) the transistor would be OFF and the relay coil would be grounded through the transistor. Current would flow through the coil, producing a magnetic field, and the relay would latch. When the instrumentation amp inputs are different, the output would saturate at +Vcc, i.e. 9V. The coil would an equal voltage at either end and so would have no voltage drop across it, meaning no current flowing through it. The relay is effectively OFF. There is a Normally Open (N.O.) Switch between pins 2 3, and 7 5 of the relay as well as Normally Closed (N.C.) Switches across pins 2 3 and 7 6. The N.O. switches close and the N.C. switches open when the relay latches. The load was connected across the N.C. pins. When the instrumentation amp has the same inputs, (zero output), and there is a voltage drop across the coil, current flows and the relay latches, disconnecting the load from the circuit. The relay had a rated voltage of 6V and the coil had a measured resistance of 70.5à ¢Ã¢â‚¬Å¾Ã‚ ¦. The relays, however, were actually found to latch at a voltage of 3.2V. Therefore for calculation purposes 3.5V is used = 49.6mA was needed to latch the relay. A potential divider was used to provide the required voltage for the relay. For a resistor R3, This caused a voltage drop across the coil, larger enough to activate the coil when necessary. The voltage across resistor R3 is given by, For Ic = 49.6mA, The Base Current of the transistor is given by For Ic = 49.6mA, and hfe = 100, To bias the base of the transistor for the 9V output of the op-amp, A 16kà ¢Ã¢â‚¬Å¾Ã‚ ¦ resistor was used. This would change VBE of the transistor. The new VBE was well within the operating range required for the resistor. Temperature Cutoff.bmp Figure : Current Protection Circuit Design of the Current Sensing Circuit The Current Sensing Circuit determined the voltage regulator output load. This value of current would be received by the ADC input. The ADC chip (ADC08040 IC ) was 4.5V. The Current LUT could convert a maximum of 1.29A. This means when the regulator reaches 1.29A, the ADC will be at 4.5V. A 1à ¢Ã¢â‚¬Å¾Ã‚ ¦ shunt resistor was placed in series with the load. The 9V regulated output would now be applied to a combined load of 10à ¢Ã¢â‚¬Å¾Ã‚ ¦. Voltage drop across the shunt: Therefore: The output voltage across the shunt is 0.9V. This will correspond with the maximum voltage which will give all 1s at the ADC output. Thus the voltage must be stepped up using a non-inverting op-amp. The voltage of 0.9V was stepped up to 4.5V. This means the gain is = 5 Let R1 = 2k à ¢Ã¢â‚¬Å¾Ã‚ ¦. Therefore, R2 = 8kà ¢Ã¢â‚¬Å¾Ã‚ ¦ The potential divider voltage was passed through the amplifier and then input into the ADC. Current Sensing Circuit.bmp Figure : Current Sensing Circuit Design of the Temperature Protection Circuit This disconnects the load from the regulator when the temperature of the Power Transistor (TIP31C) reached 40 °C. The Power Transistor temperature was monitored and at 40 °C, a signal would be sent from the circuit to a device, disconnecting the load. The LM35DZ was chosen. Its sensitivity was 10mV/ °C. At 40 °C, the temperature sensor output would be 0.4V. An instrumentation amplifier (INA114AP) was chosen to compare the temperature sensor voltage and the potential divider voltage. For a more accurate determination of the load, the temperature sensor output voltage was amplified. The potential divider delivered a voltage of 4V, and the sensor output voltage was also amplified to 4V. Therefore: Let R1 = 20kà ¢Ã¢â‚¬Å¾Ã‚ ¦ An op amp and two resistors were used to build a non-inverting amplifier in order to set the temperature sensor voltage to 4V. The reference voltage was 0.4V, since it is at this point cut-off should take place. For a non-inverting amplifier: , , Let R1=1kà ¢Ã¢â‚¬Å¾Ã‚ ¦ and R2=9kà ¢Ã¢â‚¬Å¾Ã‚ ¦, Temperature Amp Input to INA.bmp Figure : Amplifier Circuit for Comparison and Determination of Cut-off . When both input voltages are the same, the amplifier output would be 0V, turning off the transistor. (No VBE present). A 2N3904 transistor was used (Ic = 200mA), so the current would be large enough to latch the relay. If the amplifier output is not 0V, there would be a voltage drop across the base and the transistor would be ON. When the amplifier output is 0V, the transistor would be OFF, grounding the relay, causing current flow in the coil, latching the relay. When the amplifier inputs are at different levels, the output saturates at +Vcc = 9V. Equal voltages exist at both ends of the coil, so no current flows hence the relay is OFF. A Normally Open (N.O.) Switch exists across pins 2 3, and 7 5 of the relay. Normally Closed (N.C.) Switches exist across pins 2 3 and 7 6. The N.O. switches close and the N.C. switches open upon latching. Consider this load connected across the N.C pins and the amplifier has equal inputs. The amplifier output is 0V, causing a voltage drop across the relay coil, causing current flow and latching of the relay. It follows then that the load is disconnected from the circuit. For a resistor R3, R3 was used to activate the coil by creating a voltage drop across it. For Ic = 49.6mA, For biasing, A 16kà ¢Ã¢â‚¬Å¾Ã‚ ¦ resistor was used instead. Temperature Cutoff.bmp Figure : Temperature Protection Circuit This circuit was designed to relay the temperature of the power (TIP31C) to the ADC input. The ADC chip (ADC08040 IC ) reference voltage was 4.5V. The Temperature LUT could convert up to 129à ¢Ã‚ Ã‚ °C. At this temperature, the ADC should be 4.5V. A Temperature Sensor (LM35DZ) in a TO-92 package used to determine the temperature. This had a sensitivity of 10mV/ °C. At 129 °C, VO = 1.29V. Sensor output voltage was stepped up using a non-inverting op amp by a factor of , Let R1 = 1k à ¢Ã¢â‚¬Å¾Ã‚ ¦. R2 = 2.49kà ¢Ã¢â‚¬Å¾Ã‚ ¦ à ¢Ã¢â‚¬ °Ã‹â€  2.5kà ¢Ã¢â‚¬Å¾Ã‚ ¦ The sensor voltage was amplified and input into the ADC. Temperature Sensing Circuit.bmp Figure : Temperature Sensing Circuit A copper strip board was used to build the voltage regulator circuit since the solderless breadboard could only take up to 0.5A. Inputs: Voltage Supply of 15V Outputs: Voltage Sensing Output OV Ground Regulated 9V Output Temperature Sensing Voltage A voltage follower was used to buffer the output. The circuit was constructed as seen in figure 15: Figure : Complete Sensing and Cut-off Circuit DESIGN OF THE ANALOG TO DIGITAL CONVERSION CIRCUIT An 8 bit representation was used with reference to the 4.5V signal. The analog signal was converted to a digital signal from the 3 sensing circuits using the schematic shown below. Analog to digital conversion was done using the. A resistor pack was used to provide over current protection. This circuit was built and tested for each of the three sensing circuits. A combination of LEDs was used for the input of the analog voltage. AD Converter Circuit.bmp Figure : Schematic for ADC control configuration Op amps were used to buffer the inputs. The outputs were mapped onto the respective pins of the 40-pin IDE cable used to interface with the Spartan III Board. Figure : 40 Pin Expansion Connector (Spartan III Toolkit Datasheet) Data was transmitted using these pins to the ADC. DIGITAL COMPONENT The FPGA board was programmed so as to use the Seven Segment Display. Xilinx ISE 7.1i was used to design and construct the display for all the variables. Design of the Basic Display Unit Multiplexers, Frequency Dividers, a Look up Table Device and a Binary Coded Decimal to 7-Segment Converter were used to create the Display Unit. The 16-bit 31 Multiplexer Multiplexers may have more than one input but usually have one output. A combination of numbers is assigned to each input pin. Using these combinations, the respective input data is sent to the output pin. Therefore the bits that are chosen which input data set to display. In this design, two multiplexers were used, a 4-bit 41 and a 16-bit 31 multiplexer. 31 means 3 data inputs, 16- bit means each input is of 16 bit capacity. 16bit3to1muxschem.bmp Figure : Schematic Diagram of a 16-bit 3 to 1-line Multiplexer The 4-bit 41 Multiplexer The 4-bit 41 multiplexer can handle up to four combinations of inputs. To select which input is displayed, two bits are necessary. The output was a bus of width 4 bits. It split the 16 bit output into four sets of 4 bits. The 4-bit 41 multiplexer is shown in figure 19. 4bit4to1mux.bmp Figure : Schematic Diagram of a 4-bit 4 to 1-line Multiplexer Binary Coded Decimal (BCD) to 7-Segment Display Unit The BCD unit accepts four bits of data, e.g. D3D2D1D0, and determines which segments of the 7-segment display to turn on and off so as to represent the value of the input data. Figure 20 shows a 7-segment display. This type of display is common in electronic equipment e.g. calculators, microwaves, digital clocks. The Minimum Expressions for the BCD are: Seg_a = D3D2D1D0 + D2D1D0 + D3D2 + D3D1 Seg_b = D2D1D0 + D2D1D0 + D3D2 + D3D1 Seg_c = D2D1D0 + D3D2 + D3D1 Seg_d = D2D1D0 + D2D1D0 + D2D1D0 + D3D1 + D3D2 Seg_e = D0 + D2D1 + D3D1 Seg_f = D3D2 + D2D1 + D1D0 + D3D2D0 Seg_g = D3D2 + D3D1 + D2D1D0 + D3D2D1 For each expression, logic gate circuits were created. Each segment was then used to build the final BCD to 7-Segment Converter. The combinations of segments that would form the values were organised. The Look-Up-Table (LUT) This was used to determine which display unit anodes were to be turned on and off. There were four individual 7-segment displays. Each one had its own anode and as such could be controlled by choosing the anode of the respective display. lut.bmp Figure : Schematic Diagram of a Look-Up-Table (LUT) Modulo 4 Counter The Modulo 4 counter was used to perform automatic cycling of the anodes to be displayed. Only one anode was on at a time for each different combination. Moduloo4counter.bmp Figure : Schematic Diagram of a Modulo 4 Counter For multiplexed displays, the entire display is not lit up as the same time. The characters are made up of segments which, under certain conditions, become active. Each character is displayed one at a time. Switching of characters takes place so fast it appears that all the displays are on at the same time. The speed of switching is called the frequency divider (in this case 1kHz). This activates the modulo 4 counter which causes the LUT to choose one of four inputs to be chosen from the 4-bit 4 to 1 multiplexer to send to the 7 segment display. The Combined Display Unit Data Unit.bmp Figure :Schematic Diagram of the Display Unit Upgrade of the Display Unit to display the Decimal Point The LUT controls the switching of the anodes on the four 7 segment displays. Each 7 Segment Display has a decimal point that can be turned on or off if necessary. This was necessary in this project when displaying voltage and current. For a voltage, the decimal point is on the 3rd anode, a2. 0 9. 0 V For a current, the decimal point is on the 4th anode, a3. 0. 9 9 A This means that the point will only be on when S0 and S1 select to display voltage or current, and when the third or fourth anodes are on respectively. The Essential Prime Implicants were chosen from a truth table and the minimized expression was produced as follows: The Logic Gate circuit was constructed as shown below and implemented in Xilinx ISE 7.1i. A Macro was then created and connected appropriately in the Updated Display Unit Schematic. Decimal Point Upgrade.bmp Figure : Logic Gate Circuit for Decimal Point Upgrade Upgrade of the Display Unit to display the Units for each Variable The Display Unit was upgraded a second time in order to allow the units of each parameter to show Parameter Unit Symbol for Unit Voltage Volts V Current Amperes A Temperature Degrees Celsius à ¢Ã‚ Ã‚ °C Table : Parameters to be Displayed and their Respective Units The BCD Converter had to be updated to ensure when certain select bits were chosen, the segments would align to form the unit symbol on the first anode. Since there are four select inputs, D3D2D1D0 , there are 16 possible combinations of these bits forming different outputs. 0000 to 1001 in binary form represents 0 to 9 in decimal form. This means that there are combinations 1010 to 1111 to choose from to display a unit. 1101 was chosen for voltage, 1110 for current and 1111 for temperature. Figure : Common

Dr. Faustus Essay: The Tragic Downfall of Dr. Faustus -- Doctor Faust

The Tragic Downfall of Dr. Faustus Christopher Marlowe's play, its genre an English tragedy of the sixteenth century, presents the tragic conflict of the Faust theme in the tradition of medieval morality plays. The concepts of good and evil in these plays and their psychological implications reflect a historical background in which the church dominates the ethical and moral concepts of their time. Faustus defies society's norms and embraces the devil with courageous desperation, fully aware of the inevitable consequences, but incapable of being satisfied with his human limitations. The play is divided into five acts, each of them representing a progressive stage of Faustus' downfall, his moral and ethical decline. In the prologue preceeding the first act, which is written in the form of a poetic commentary, Faustus is allegorically compared to Ikarus, the Greek mythological figure, through the alliteration of "waxen wings" (Prologue line 20). Ikarus' actual flight represents symbolically Faustus' intellectual endeavors to unreached heights. The melting of Ikarus' wings find their parallel in Faustus' downfall and destruction. The language used, discloses hierarchical thought pattern: scholarly pursuits are high standing in value. The closeness to the sun that causes Ikarus' fall foreshadows Faustus' destruction and his desire to become like God. This reflects the pre-renaissance understanding of social order - people are to stay in their "God-given" place in society. But the image of Ikarus' death is also to be taken literal. "Heavens conspired his overthrow" (Prologue line 21) foretells Faustus' actual death while the blame for it is being placed scornfully and s... ...t of sin, "but Faustus, in hell is all manner of delight"(II,ii,179). The struggle between Faustus' superego/good angel and his id/bad angel continue throughout the play and the possibility of achieving a balance doesn't seem to exist. In the society of the sixteenth century repressive moral standards prohibited a possible balance between ethical demands and human passions, causing psychological traumas as the reader can observe it in this play. Society of this time, forcing their limited understanding of God on people, caused thinkers like Faust to lose their chance for a supernatural experience with God that could have solved their questions. It would take another two hundred years until in the period of Enlightenment a new Faust, created by Goethe, would retain his noble character and conquer with reason the trivial attempts of Mephistopheles.