Diversity Essay Samples

Diversity Essay SamplesThere are several different ways to prepare your college-level diversity essay samples. Some students do this by selecting hundreds of essays from the many publications online. They then select the best ones and use them to write the college level diversity essay that will be required in their specific class. It is also possible to simply find your own essay samples, but sometimes it is easier to find samples from books or from popular websites that can be used as a guide.The first thing to remember when choosing your college-level diversity essay sample is to pick an essay that you find interesting. You will not want to write a boring or dry essay. You will also want to make sure that you keep to the style guide that was used for the paper that you are writing for college.The question that many students find is whether or not to use a variety of essay formats for their college-level diversity essay. A good way to do this is to use them to get your ideas writte n out. Using this format allows you to easily check and change the words or topics that you want changed. This is especially useful if you are working on multiple sections of the paper.You should make sure that you choose the best college level diversity essay samples for your specific assignment. The best thing to do is to check out the essay samples on sites like LiveScience.com, Wikipedia.org, etc. These sites allow you to type in the words or phrases that you want changed and then check the spelling and the correctness of the words.These essay samples allow you to see what are the common mistakes that are found. There are times when people simply write incorrect information in their essays. Not only does this happen in college, but also in the workplace. If you want to find a sample that is written correctly then you should check out thefree essays that are available through the internet.Many of the essay samples that are found online do not allow for the writer to change the wo rds that they use. In this case, you will want to visit a website where you can type in a phrase and have it checked for grammar and usage. If there are any mistakes then you will want to correct them before you submit your essay.There are a lot of reasons why you would want to use college-level diversity essay samples. If you want to improve your writing skills, then these are excellent resources that you should consider.

Arthur Schopenhauer s Suicide As An Experiment - 1719 Words

Arthur Schopenhauer describes suicide as an experiment, a question that man puts to nature and demands an answer. The majority of those who commit suicide don’t have Schopenhauer s idea of experimentation in mind, but rather their mind is clouded by depression and stress. Suicide is not a danger that disproportionately affects the expected teen and young adults, but it has sunk its teeth into an unlikely demographic, and the way to combat this beast is still unclear. The most classically expected group to commit suicide in numbers much higher than the rest of the population are those that are teenagers and young adults. Suicide rates in middle aged men have witnessed a sharp increase, the baby boomers have become the surprising group to be affected by suicide most, even outnumbering teenagers and the elderly (Parker-Pope). The group of baby boomers who is now most prone to suicide has actually had higher rates of suicide across their entire lives (Phillips). The newest discovery that the group who is now most likely to commit suicide should logically be the happiest and some of the most mature, but for various reasons the middle aged have become the most at risk for suicide. With about 30 out of 100,000 middle aged men committing suicide compared to about 11 in 100,000 teens and young adults committing suicide, experts have been analyzing why such a sharp increase has occurred amongst those in midlife, and why it is so much larger than the group of young people who are

Wave Energy System

Sample details Pages: 18 Words: 5306 Downloads: 1 Date added: 2017/06/26 Category Statistics Essay Did you like this example? 1.0 Executive Summary The offshore ocean wave energy resource, as a derivative form of solar energy, has considerable potential for making a significant contribution to the alternative usable energy supply.Wave power devices are generally categorized by the method used to capture the energy of the waves. They can also be categorized by location and power take-off system. The energy extraction methods or operating principles can be categorized into three main groups; (1) Oscillating water Column (OWC) (2) Overtopping Devices (OTD) (3) Wave Activated Bodies (WAB); Locations are shoreline, near shore and offshore. This report discusses about Terminator wave energy devices which extend perpendicular to the direction of wave travel and capture or reflect the power of the wave. These devices are typically onshore or near shore; however, floating versions have been designed for offshore applications. Don’t waste time! Our writers will create an original "Wave Energy System | Engineering Dissertations" essay for you Create order 2.0 Introduction Traditional sources of energy such as oil, gas, and coal are non-renewable. They also create pollution by releasing huge quantities of carbon dioxide and other pollutants into the atmosphere. In contrast, waves are a renewable source of energy that doesnt cause pollution. The energy from waves alone could supply the worlds electricity needs. The total power of waves breaking on the worlds coastlines is estimated at 2 to 3 million megawatts. In some locations, the wave energy density can average 65 megawatts per mile of coastline. The problem is how to harness wave energy efficiently and with minimal environmental, social, and economic impacts. Ocean waves are caused by the wind as it blows across the open expanse of water, the gravitational pull from the sun and moon, and changes in atmospheric pressure, earthquakes etc. Waves created by the wind are the most common waves and the waves relevant for most wave energy technology. Wave energy conversion takes advantage of the ocean waves caused primarily by the interaction of winds with the ocean surface. Wave energy is an irregular oscillating low-frequency energy source. They are a powerful source of energy, but are difficult to harness and convert into electricity in large quantities. The energy needs to be converted to a 60 or 50 Hertz frequency before it can be added to the electric utility grid. Part of the solar energy received by our planet is converted to wind energy through the differential heating of the earth. In turn part of the wind energy is transferred to the water surface, thereby forming waves. While the average solar energy depends on factors such as local climate and latitude, the amount of energy transferred to the waves and hence their resulting size depends on the wind speed, the duration of the winds and the duration over which it blows. The most energetic waves on earth happen to be between 30 degrees to 60 degrees latitude, in general the waves generated are stronger on the southern parts of the countries (John brook, ECOR). Wave power devices extract energy directly from the surface motion of ocean waves or from pressure fluctuations below the surface. Wave power varies considerably in different parts of the world, and wave energy cant be harnessed effectively everywhere. It has been estimated that if less than 0.1% of the renewable energy available within the oceans could be converted into electricity, it would satisfy the present world demand for energy more than five times over. A variety of technologies are available to capture the energy from waves. Wave technologies have been designed to be installed in near shore, offshore, and far offshore locations. Offshore systems are situated in deep water, typically of more than 40 meters (131 feet). Types of power take-off include: hydraulic ram, elastomeric hose pump, pump-to-shore, hydroelectric turbine, air turbine and linear electrical generator. Some of these designs incorporate parabolic reflectors as a means of increasing the wave energy at the point of capture. 3.0 Type of Wave Energy Converters Ocean waves represent a form of renewable energy created by wind currents passing over open water. Many devices are being developed for exploiting wave energy. The energy extraction methods or operating principles can be categorized into three main groups (Harris Robert E. et al.): Oscillating Water Columns (OWC) Waves cause the water column to rise and fall, which alternately compresses and depressurize an air column. The energy is extracted from the resulting oscillating air flow by using a Wells turbine Overtopping Devices (OTD) Ocean waves are elevated into a reservoir above the sea level, which store the water. The energy is extracted by using the difference in water level between the reservoir and the sea by using low head turbines Wave Activated Bodies (WAB) Waves activate the oscillatory motions of body parts of a device relative to each other, or of one body part relative to a fixed reference. Primarily heave, pitch and roll motions can be identified as oscillating motions whereby the energy is extracted from the relative motion of the bodies or from the motion of one body relative to its fixed reference by using typically hydraulic systems to compress oil, which is then used to drive a generator. The wave activated bodies (WABs) can be further categorized in sub-groups describing the energy extraction by the principle motion of the floating body (heave, pitch and roll). A variety of technologies have been proposed to capture the energy from waves based on above extraction methods; Some of the technologies that have been the target of recent developmental efforts and are appropriate for the offshore applications being considered are terminators, attenuators and point absorbers (U.S. Department of the Interior, May 2006). Figure 1: Schematic drawings of WEC devices for operating principles and principal locations(Harris Robert E. et al.) The many different types of wave energy converters (WECs) can be classified in to various ways depending on their horizontal size and orientation. If the size is very small compared to the typical wavelength the WEC is called a point absorber. In contrast if the size is comparable to or larger than the typical wavelength, the WEC is known as line absorber, this can also be referred to as terminator or attenuator. A WEC is called terminator or attenuator if it is aligned along or normal to the prevailing direction of the wave crest respectively (John brook, ECOR). The relationship between the three main classifications Principal Location Operating Principle Directional Characteristic: These classifications are shown in Figure 2, presenting the possible operating principles for the location and the directional characteristics. At the shoreline the only feasible operating principles are oscillating water columns and overtopping devices, which are terminators. Figure shows that at near shore and offshore, point absorber or attenuator devices can only be WABs, whilst for terminator devices all three categories of the operating principles are possible. OWCs and OTDs are static energy converters of the terminator kind. As a result their mooring has to be stiff, restraining modes of motions but allowing for adjustment towards a parallel wave approach and for tidal ranges. The station keeping requirements for the mooring of wave activated bodies can be either static or dynamic. Figure 2: Possible operating principles for the principal location and directional characteristic 3.1 Attenuators Attenuators are long multi-segment floating structures oriented parallel to the direction of the wave travel. The differing heights of waves along the length of the device causes flexing where the segments connect, and this flexing is connected to hydraulic pumps or other converters (U.S. Department of the Interior, May 2006). 3.2 Point Absorbers Point absorbers have a small horizontal dimension compared with the vertical dimension and utilize the rise and fall of the wave height at a single point for WEC (Harris Robert E. et al.). It is relatively small compared to the wave length and is able to capture energy from a wave front greater than the physical dimension of the absorber (James, 2007). The efficiency of a terminator or attenuator device is linked to their principal axis being, according, parallel or orthogonal to the incoming wave crest. The point absorber does not have a principal wave direction and is able to capture energy from waves arriving from any direction. As a consequence the station keeping for the terminator and attenuator has to allow the unit to weathervane into the predominant wave direction, but this is not necessary for the point absorber (Harris Robert E. et al.). 3.3 Terminators A Terminator has its principal axis parallel to the incident wave crest and terminates the wave. These devices extend perpendicular to the direction of wave travel and capture or reflect the power of the wave. The reflected and transmitted waves determine the efficiency of the device (Harris Robert E. et al.). These devices are typically installed onshore or near shore; however, floating versions have been designed for offshore applications. (U.S. Department of the Interior, May 2006). There are mainly two types in Terminator WEC. 3.3.1 Oscillating Water Columns (OWC) The oscillating water column (OWC) is a form of terminator in which water enters through a subsurface opening into a chamber with air trapped above it. The wave action causes the captured water column to move up and down like a piston to force the air through an opening connected to a turbine (U.S. Department of the Interior May 2006). The device consists essentially of a floating or (more usually) bottom-fixed structure, whose upper part forms an air chamber and whose immersed part is open to the action of the sea. The reciprocating flow of air displaced by the inside free surface motion drives an air turbine mounted on the top of the structure. 3.3.1.1 Efficiency of Oscillating Water Column (OWC) The efficiency of oscillating water column (OWC) wave energy devices are particularly affected by flow oscillations basically for two reasons. (1) Because of intrinsically unsteady (reciprocating) flow of air displaced by the oscillating water free surface. (2) Because of increasing the air flow rate, above a limit depending on, and approximately proportional to, the rotational speed of the turbine, is known to give rise to a rapid drop in the aerodynamic efficiency and in the power output of the turbine. A method which has been proposed to partially circumvent this problem consists in controlling the pitch of the turbine rotor blades in order to prevent the instantaneous angle of incidence of the relative flow from exceeding the critical value above which severe stalling occurs at the rotor blades (see Gato and Falcao, 1991). Although considered technically feasible (Salter, 1993) this has never been implemented at full scale owing to mechanical difficulties. Alternately, the flow rate through the turbine can be prevented from becoming excessive by equipping the device with air valves. Two different schemes can be envisaged, in the first one, the valves are mounted between the chamber and the atmosphere in parallel with the turbine (by-pass or relief valves, on or near the roof of the air chamber structure) and are made to open (by active or passive control) in order to prevent the overpressure (or the under pressure) in the chamber to exceed a limit which is defined by the aerodynamic characteristics of the turbine at its instantaneous speed. In the second scheme a valve is mounted in series with the turbine in the duct connecting the chamber and the atmosphere. Excessive flow rate is prevented by partially closing the valve. In both schemes, the air flow through the turbine is controlled at the expense of energy dissipation at the valves. Theoretically the two methods, if properly implemented, are equivalent from the point of view of limiting the flow rate through the turbine. However, the resulting pressure changes in the chamber are different (reduction and increase in pressure oscillations in the first and second cases, respectively). Consequently the hydrodynamic process of energy extraction from the waves is differently modified by valve operation in the two control methods. The main purpose of this work is to analyse theoretically the performance of an OWC wave energy device when valves are used to limit the flow through the turbine. Both schemes are considered and compared: a valve (or a set of valves) mounted in parallel with the turbine (by-pass or relief valve) or a valve mounted in the turbine duct. The hydrodynamic analysis is done in the time domain for regular as well as for irregular waves. The spring-like effect due to the compressibility of the air is taken into account and is discussed in some detail. Realistic characteristics are assumed for the turbine. Numerical results are presented for simple two-dimensional chamber geometry for whose hydrodynamic coefficients analytical expressions are known as functions of wave frequency. 3.3.2 Overtopping Devices (OTD) Overtopping devices have reservoirs that are filled by impinging waves to levels above the average surrounding ocean. The released reservoir water is used to drive hydro turbines or other conversion devices. Overtopping devices have been designed and tested for both onshore and floating offshore applications. It gathers the energy by waves overtopping into a raised reservoir, and extracting this by draining the water through low head turbines. OTD consists of three main elements: Two wave reflectors. Attached to the central platform these act to focus the incoming waves. The main platform. This is a floating reservoir with a doubly curved ramp facing the incoming waves. The waves overtop the ramp which has a variable crest freeboard 1 to 4 m and underneath the platform open chambers operate as an air cushion maintaining the level of the reservoir. Hydro turbines. A set of low head turbines converts the hydraulic head in the reservoir (Tedd James et al., 2005) 3.3.2.1 Overtopping theory The theory for modeling overtopping devices varies greatly from the traditional linear systems approach used by most other WECs. A linear systems approach may be used with overtopping devices. This considers the water oscillating up and down the ramp as the excited body, and the crest of the ramp as a highly non-linear power take off system. However due to the non-linearities it is too computationally demanding to model usefully. Therefore a more physical approach is taken. Figure 4 shows the schematic of flows for the Wave Dragon. Depending on the current wave state (HS, Tp) and the crest freeboard Rc(height of the ramp crest above mean water level, MWL) of the device, water will overtop into the reservoir Qovertopping. The power gathered by the reservoir is a product of this overtopping flow, the crest freeboard and gravity. If the reservoir is over filled when a large volume is deposited in the basin there will be loss from it Qspill. To minimize this, the reservoir level h must be kept below its maximum level hR. The useful hydraulic power converted by the turbines is the product of turbine flow Qturbine, the head across them, water density and gravity (Tedd James et al., 2005). In coastal engineering the average flow Q is converted into non dimensional form by dividing by the breadth of the device b, gravity g and the significant wave height HS: In the case of the floating OTD it has been seen that there is a dependency on the wave period. The dominant physical explanation for this is the effect of energy passing beneath the draft of the structure. Figure 6 Layout of OTD 3.3.2.2 Wave Reflector Wings One of the most distinctive aspects of the Overtopping WEC is the long slender wings mounted to the front corners of the reservoir platform. These are designed to reflect the oncoming waves towards the ramp. A wider section of wave is available to be exploited with only a moderate increase in capital cost. The overtopping volume in a wave is very dependent on the wave height; therefore by providing only a moderate increase in height, much more energy can overtop the ramp. In order to choose the correct lengths, angles, and position of these wings extensive computer modelling is used. Secondary bonuses of the presence of the wave reflector wings include: better weather-vaning performance to face the waves, lower peak mooring forces, and improved horizontal stability of the main platform. As the aft and rear mooring attachment points are separated further, the yaw of the platform is more stable. Therefore the device will not turn away from the predominant wave direction, and will also realign itself faster as when the wave direction changes (Tedd James et al., 2005). Lastly the reflectors wings act as stabilisers to the device. As they float under their own buoyancy they counteract any list of the platform. This is important as the more horizontal the platform is kept the less water is spilt and so the more efficient the device operation. 3.3.2.3 Low Head Turbines and Power Train Turbine operating conditions in a WEC are quite different from the ones in a normal hydro power plant. In the OTD, the turbine head range is typically between 1.0 and 4.0 m, which is on the lower bounds of existing water turbine experience. While there are only slow and relatively small variations of flow and head in a river hydro power plant, the strong stochastic variations of the wave overtopping call for a radically different mode of operation in the OTD. The head, being a function of the significant wave height, is varying in a range as large as 1:4, and the discharge has to be regulated within time intervals as short as ten seconds in order to achieve a good efficiency of the energy exploitation (Tedd James et al., 2005). On an unmanned offshore device, the environmental conditions are much rougher, and routine maintenance work is much more difficult to perform. Special criteria for the choice and construction of water turbines for the WEC have to be followed; it is advisable to aim for constructional simplicity rather than maximum peak efficiency. Figure 6 shows the application ranges of the known turbine types in a graph of head H vs. rotational speed nq. The specific speed nq is a turbine parameter characterizing the relative speed of a turbine, thus giving an indication of the turbines power density. Evidently, all turbine types except the Pelton and the cross flow type are to be found in a relatively narrow band running diagonally across the graph. Transgressing the left or lower border means that the turbine will run too slowly, thus being unnecessarily large and expensive. The right or upper border is defined by technological limits, namely material strength and the danger of cavitations erosion. The Pelton and the cross-flow turbine do not quite follow these rules, as they have a runner which is running in air and is only partially loaded with a free jet of water. Thus, they have a lower specific speed and lower power density. Despite its simplicity and robustness, the cross flow turbine is not very suitable for OTD applications (Tedd James et al., 2005). Figure 7 Head range of the common turbine types, Voith and Ossberger 3.3.2.4 Performance in Storms Survivability is essential, and Overtopping devices are naturally adapted to perform well in storm situations, where the wave will pass over and under the device with no potential end-stop problems. 3.3.2.5 Wave Prediction Performance of almost all wave energy converters can be improved with prediction of the incoming waves. The cost to implement would be low as the control hardware is typically in place, only the measuring system and improved control techniques need to be developed. To explain the concept behind the device a simple example can be used. If a measurement of some wavelengths ahead of the wave energy converter shows large waves passing, then at a given time later this energy will be incident on the device. The control of the device can then be altered quickly to extract this larger energy, e.g. by increasing hydraulic resistance to an oscillators motion allowing more energy to be captured within the stroke length, or by draining the reservoir of an overtopping device to allow for a large overtopping volume(Tedd James et al., 2005). The challenges are threefold; to implement a system for measuring the waves approaching the ramp, to accurately transform this into usable input for the control systems, and to construct new control strategies to make the best use of this. The standard approach for performing such deterministic sea-state prediction involves discrete frequency domain techniques. This is computationally intensive, as the two Fourier transforms must be made to convert from the time domain to the frequency domain and return to the time domain. 3.4 Energy Capture and Practical Limits The power captured from waves by the primary mechanical conversion (before secondary conversion to electrical power) can be related to the energy in the incoming waves over a certain width. Theoretical values have been established in some cases. For a heaving axi-symmetric body the maximum capture width is the inverse of the wave number. The capture width is often compared to the front width of the device. This width ratio can be larger than one for a point absorber with small dimensions compared to the wavelength. Viscous effects reduce efficiency. For an OWC, Wang et al. (2002) found that the capture width ratio may reach a value of 3 and above at an optimum wave period. For Pelamis, Retlzler et al. (2001) found a capture width up to 2 in regular waves and around one in random seas (Specialist Committee V.4, 2006). A continuous or a semi discrete array of wave energy converters acting as an absorbing wall perpendicular to the wave direction is called a terminator and its capture width equals the width of the device and is not related to the length of the incident waves. As the wave conditions are stochastic, the tuning parameters of the energy converters are compromises between the optimum values at various sea conditions. The capture width must be established for each sea state. Fixed devices are subject to sea level variation according to tidal effects. This is critical for fixed oscillating water columns and fixed overtopping systems whose performances are dependent on the mean sea level. The intake of an OWC must be located at an optimised design level from the mean free surface. The height of an overtopping system is also optimised for sea states occurring at a given mean sea level. Therefore, sites with minimal tide are preferred. From this point of view floating devices are more suitable. The immersion of a floating device can also be tuned with respect to the actual sea state. For instance the Wave Dragon overtopping device is partially floating on air chambers and its draught can be modified (Specialist Committee V.4, 2006). The performance of the overtopping device is sensitive to the distribution of the overtopping rate. The more variable the overtopping flow into the reservoir, the larger the capacity of the reservoir and turbines must be to achieve the same performance. 4.0 Mooring Requirements The two major requirements for a WEC mooring are to withstand the environmental and other loadings involved in keeping the device on station, and to be sufficiently cost effective so that the overall economics of the device remain viable. The following list shows the requirements that need to be considered for WEC moorings systems (Harris Robert E. et al.): The primary purpose of the mooring system is to maintain the floating structure on station within specified tolerances under normal operating load and extreme storm load conditions. The excursion of the device must not permit tension loads in the electrical transmission cable(s) and should allow for suitable specified clearance distances between devices in multiple installations. The mooring system must be sufficiently compliant to the environmental loading to reduce the forces acting on anchors, mooring lines and the device itself to a minimum; unless the stiffness of the mooring itself is an active element in the wave energy conversion principle used. All components must have adequate strength, fatigue life and durability for the operational lifetime, and marine growth and corrosion need to be considered. A degree of redundancy is highly desirable for individual devices, and essential for schemes which link several devices together. The system as a whole should be capable of lasting for 30 years or more, with replacement of particular components at no less than 5 years. The mooring must be sufficient to accommodate the tidal range at the installation location. The mooring system should allow the removal of single devices without affecting the mooring of adjacent devices. Removal of mooring lines for inspection and maintenance must be possible. The mooring must be sufficiently stiff to allow berthing for inspection and maintenance purposes. Contact between mooring lines must be avoided. The mooring should not adversely affect the efficiency of the device, and if it is part of an active control system it must also be designed dynamically as part of the overall WEC system. Revenues from WECs, in comparison to the offshore industry, are smaller and their economics more strongly linked to the location, installation costs and down time periods. The mooring system has an important impact on the economics and it is necessary to provide, at low installation cost, a reliable system that has little downtime and long intervals between maintenance. The suitability of design approaches from the offshore industry for WECs are ranked in Appendix I (Harris Robert E. et al.). 5.0 Environmental Considerations Conversion of wave energy to electrical or other usable forms of energy is generally anticipated to have limited environmental impacts. However, as with any emerging technology, the nature and extent of environmental considerations remain uncertain. The impacts that would potentially occur are also very site specific, depending on physical and ecological factors that vary considerably for potential ocean sites. As large-scale prototypes and commercial facilities are developed, these factors can be expected to be more precisely defined (U.S. Department of the Interior, May 2006). The following environmental considerations require monitoring (U.S. Department of the Interior, May 2006). Visual appearance and noiseare device-specific, with considerable variability in visible freeboard height and noise generation above and below the water surface. Devices with OWCs and overtopping devices typically have the highest freeboard and are most visible. Offshore devices would require navigation hazard warning devices such as lights, sound signals, radar reflectors, and contrasting day marker painting. However, Coast Guard requirements only require that day markers be visible for 1 nautical mile (1.8 km), and thus offshore device markings would only be seen from shore on exceptionally clear days. The air being drawn in and expelled in OWC devices is likely to be the largest source of above-water noise. Some underwater noise would occur from devices with turbines, hydraulic pumps, and other moving parts. The frequency of the noise may also be a consideration in evaluating noise impacts. Reduction in wave height from wave energy converterscould be a consideration in some settings; however, the impact on wave characteristics would generally only be observed 1 to 2 km away from the WEC device in the direction of the wave travel. Thus there should not be a significant onshore impact if the devices were much more than this distance from the shore. None of the devices currently being developed would harvest a large portion of the wave energy, which would leave a relatively calm surface behind the devices. It is estimated that with current projections, a large wave energy facility with a maximum density of devices would cause the reduction in waves to be on the order of 10 to 15%, and this impact would rapidly dissipate within a few kilometers, but leave a slight lessening of waves in the overall vicinity. Little information is available on the impact on sediment transport or on biological communities from a reduction in wave height offshore. An isolated impact, such as reduced wave height for recreational surfers, could possibly result. Marine habitatcould be impacted positively or negatively depending on the nature of additional submerged surfaces, above-water platforms, and changes in the seafloor. Artificial above-water surfaces could provide habitat for seals and sea lions or nesting areas for birds. Underwater surfaces of WEC devices would provide substrates for various biological systems, which could be a positive or negative complement to existing natural habitats. With some WEC devices, it may be necessary to control the growth of marine organisms on some surfaces. Toxic releasesmay be of concern related to leaks or accidental spills of liquids used in systems with working hydraulic fluids. Any impacts could be minimized through the selection of nontoxic fluids and careful monitoring, with adequate spill response plans and secondary containment design features. Use of biocides to control growth of marine organisms may also be a source of toxic releases. Conflict with other sea space users, such as commercial shipping and fishing and recreational boating, can occur without the careful selection of sites for WEC devices. The impact can potentially be positive for recreational and commercial fisheries if the devices provide for additional biological habitats. Installation and Decommissioning: Disturbances from securing the devices to the ocean floor and installation of cables may have negative impacts on marine habitats. Potential decommissioning impacts are primarily related to disturbing marine habitats that have adapted to the presence of the wave energy structures. 6.0 Discussions A vast number of parameters influence (and interact with) the net power production from any WEC: Overtopping, determined by Free-board (adjustable in Wave Dragons) Actual wave height Physical dimension of the converter (ramps, reflectors etc. Outlet, determined by Size of reservoir Turbine design Turbine on/off strategy Mooring system, free or restricted orientation toward waves Size of the energy converter Wave climate Energy in wave front (kW/m) Distribution of wave heights Availability Theoretical availability; Reliability, maintainability, serviceability Accessibility on the site Maintenance strategy In general terms wave energy generation has the following advantages and disadvantages. Advantages: The energy is free no fuel is needed and no waste is produced Not expensive to operate and maintain Can produce a significant amount of energy. Disadvantages: Depends on the waves variable energy supply Needs a suitable site, where waves are consistently strong Some designs are noisy Must be able to withstand very rough weather Costly to develop Visual impact if above water or on shore Can disturb or disrupt marine life including changes in the distribution and types of marine life near the shore Poses a possible threat to navigation from collisions due to the low profile of the wave energy devices above the water, making them undetectable either by direct sighting or by radar May interfere with mooring and anchorage lines with commercial and sport-fishing May degrade scenic ocean front views from wave energy devices located near or on the shore, and from onshore overhead electric transmission lines. 7.0 Conclusion Despite inventors actively making systems to capture power from the waves, for the last two centuries, there is still not a wide application of wave energy devices as power generators. The availability of devices to fit different applications is not the problem the technology is definitely there. The reality is that the only long term problem is making the technology work at a cost of power which a consumer is willing to pay. The system will work itself out. The price of fossil fuel generation will become more and more expensive and wave generated power will fall in price. One of the biggest difficulties is in introducing a new, fledgling technology into a commercial market dominated by subsidised low cost fossil fuel and nuclear generation. 8.0 References HARRIS ROBERT E., JOHANNING LARS WOLFRAM JULIAN Mooring systems for wave energy converters: A review of design issues and choices. JAMES, T. (2007) Testing, Analysis and Control of Wave Dragon, Wave Energy Converter. Civil Engineering. Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark, Aalborg University. SPECIALIST COMMITTEE V.4 (2006) Ocean Wind and Wave Energy Utilization. 16th International Ship and Offshore Structures Congress, 1. TEDD JAMES, KOFOED JENS PETER FRIIS-MADSEN ERIK (2005) Renovation of the Wave Dragon Nissum Bredning Prototype. Department of Civil Engineering. Aalborg, Aalborg University. U.S. DEPARTMENT OF THE INTERIOR (May 2006) Technology White Paper on Wave Energy Potential on the U.S. Outer Continental Shelf. Minerals Management Service Renewable Energy and Alternate Use Program Appendix I: Possible Mooring Configurations And Suitability For Wave Energy Converter The wording high, medium and low is mainly used to describe the suitability of these mooring configurations in relation to safe station keeping and moderate installation costs.

Essay on The Odyssey and the Epic of Gilgamesh - 847 Words

The Odyssey and The Epic of Gilgamesh (Similarities and Differences) Both The Odyssey and the Epic of Gilgamesh are two incredible stories written long ago everyone knows this but what a lot of people dont is that these two epics share many of the same concepts. Such as the nostro (the Greek term for homecoming), xenis (guest/host relationship), oikos (household), and aganoriss (recognition). In both epics these themes are illustrated. In The Odyssey the theme of nostro is very prevalent in this epic. Basically the whole story is based around this concept. The main character Odysseus whole goal in the book is his homecoming. Along his journey he faces many challenges separating him from his home Ithaca and his family.†¦show more content†¦He then stays with him and is treated like a guest. It seems in this epic xenis does not play as an important role as it does in The Odyssey. Therefore this is where these two would differ. Much of the Odyssey is based upon this theme. Another theme oikos is integrated into the Odyssey. The household in this epic seems to be an important structure in the relationship between Odysseus, Penelope, and their son Telemachus. After all it is their household that is threatened by the suitors and leads Telemachus to search for the truth about the whereabouts of his father. Also the peril of the suitors exhausting Odysseus resources and household drive him to kill the suitors. Which also plays into the story well. To me it seems as though these themes play more of a role in this epic. Okios is represented differently in the epic. It is apparent that in this epic the household is held as less important due to the fact that Gilgamesh corrupts other households by sleeping with the virgins before they are married, an abuse of power. It is not held to as high a standard as it is in the Odyssey. Not say Odysseus does stray from his wife but Gilgamesh makes a point of it. It is not until the end when he realizes the importance of family and ht household. The last of the themes that appear in the Odyssey is the theme of recognition, or aganoriss. Recognition is essential to Odysseus whenShow MoreRelatedThe Epic Of Gilgamesh And The Odyssey1636 Words   |  7 PagesThe Epic of Gilgamesh and the Odysseus both are poems that have since early times been viewed as stories that teach the reader valuable life lessons, almost like a self-help book in today’s society. They both teach a lot of the same general lessons but there are some key similarities and differences throughout both works. Such as perseverance, and the inevitability of death are both lessons that are taught in each poem but they are presented to the reader through different interpretations. In theRead MoreThe Epic Of Gilgamesh And The Odyssey Essay790 Words   |  4 Pagestaken by characters as a tool to exhibit the alteration of the character’s nature. 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Human Trafficking Is A Global Problem Essay - 894 Words

Introduction Human Trafficking is defined by Merriam – Websters dictionary , as the organized criminal activity in which human beings are treated as possessions to be controlled and exploited as by being forced into prostitution or involuntary labor . Human trafficking is one of the fastest growing trans national organized criminal activities generating an estimated $ 32 billion in annual revenue 2013 ( Wikipedia.)In the sex industry side of human trafficking a single girl can earn her pimp up to staggering 250,000 dollars a year. Human trafficking is a massive global problem that has not only many reasons people are trafficked, but several root causes that aid traffickers in pulling victims in . There is an estimated 27 million adults and 13 million children who are the victims of human trafficking (randomfacts.com.) When you hear the term human trafficking most people s first thought is the sex slave aspect of human trafficking . While this is the most common reason for trafficking humans, there is also the forced labor and organ harvesting side of this criminal activity . All the aspects of this horrid crime need to be discussed to fully understand the problem . First and most common is the sex industry . Ludwig â€Å"Tarzan† Fainbrg , a convicted trafficker , said, â€Å" You can buy a woman for $ 10,000 and make your money back in a week ifShow MoreRelatedHuman Trafficking Is A Global Problem1207 Words   |  5 Pagesextensively in the past and during our time on the United Nations Security Council to combat injustices around the globe and also to help nations in need. Some of the issues that our government has been especially focused on i nclude the prevention of human trafficking, whether or not admit Palestine, Kosovo, and Taiwan to the United Nations, and which nation should have domain over the South China Sea. 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Arizona Concrete Essay Example For Students

Arizona Concrete Essay ARIZONA CONCRETEJohn McCollamGeology 101, Section 12262Randy Porch20 November 1996ARIZONA CONCRETEAccording to the Mine Faculty at the University of Arizona, cement is manufactured primarily from suitable limestone and shale rocks. Arizona had two dry-process cement plants in 1969, namely the Arizona Portland Cement Company plant in Pima County, near Tucson, and the American Cement Corporation plant at Clarkdale, in Yavapai County (52-53). The use of cementing materials goes back to the ancient Egyptians and Romans, but the invention of modern portland cement is usually attributed to Joseph Aspdin, a builder in Leeds, England, who obtained a patent for it in 1824. Currently, the annual world production of portland cement is around 700 million metric tons (Danbury). Many people use the words concrete and cement interchangeably, but they=re not. Concrete is to cement as a cake is to flour. Concrete is a mixture of ingredients that includes cement but contains other ingredients also (Day 6-7). Portland cement is produced by pulverizing clinker consisting essentially of hydraulic calcium silicates along with some calcium aluminates and calcium aluminoferrites and usually containing one or more forms of calcium sulfate (gypsum) as an interground addition. Materials used in the manufacture of portland cement must contain appropriate proportions of calcium oxide, silica, alumina, and iron oxide components. During manufacture, analyses of all materials are made frequently to ensure a uniformly high quality cement. Selected raw materials are crushed, milled, and proportioned in such a way that the resulting mixture has the desired chemical composition. The raw materials are generally a mixture of calcareous (calcium oxide) material, such as limestone, chalk or shells, and an argillaceous (silica and alumina) material such as clay, shale, or blast-furnace slag. Either a dry or a wet process is used. In the dry process, grinding and blending operations are done with dry materials. In the wet process, the grinding and blending are done with the materials in slurry form. In other respects, the dry and wet processes are very much alike. After blending, the ground raw material is fed into the upper end of a kiln. The raw mix passes through the kiln at a rate controlled by the slope and rotational speed of the kiln. Burning fuel (powdered coal, oil, or gas) is forced into the lower end of the kiln where temperatures of 2600F to 3000F change the raw material chemically into cement clinker, grayish-black pellets about the size of 1/2-in.-diameter marbles. The clinker is cooled and then pulverized. During this operation a small amount of gypsum is added to regulate the setting time of the cement. The clinker is ground so fine that nearly all of it passes through a No. 200 mesh (75 micron) sieve with 40,000 openings per square inch. This extremely fin gray powder is portland cement (Kosmatka and Panarese 12-15). Dany Seymore of Show Low Ready Mix said that the cement used by Show Low Ready Mix is trucked in by Apex Freight Company and comes from the cement plant in Clarkdale, Arizona, now know as Phoenix Cement. Their aggregate comes from Brimhall Sand and Rock in Snowflake, Arizona. Show Low Ready Mix uses Fly Ash from the A.P.S. power plant just out side of Joseph City, Arizona, in their cement. The mixtures they use are as follows:Silicia DioxideCement 21% Ash 62%Aluminum TrioxideCement 4%Ash 23%Ferric OxideCement 3%Ash 6%Calcium OxideCement 64%Ash 3.5%Mag. OxideCement 2.5%Ash 1.2%Sulfur TrioxideCement 3%Ash .2%These combine to make:1. Tricalcium silicate C3S2. Dicalcium silicate C2S3. Tricalcium aluminate C3A4. Tetracalcium aluminoferrite C4AF1 and 2 make up 75% of cement. 1 and 2 plus H2O equal CSH (Calcium Silicate Hydrate) which is the glue. Fly Ash is C3S plus C2S which equals Calcium hydrazide which is a white stuff and water soluble. Calcium Hydrazide and Fly Ash equal CSH. .ubf708910504e97e39d29594bd3f3a62b , .ubf708910504e97e39d29594bd3f3a62b .postImageUrl , .ubf708910504e97e39d29594bd3f3a62b .centered-text-area { min-height: 80px; position: relative; } .ubf708910504e97e39d29594bd3f3a62b , .ubf708910504e97e39d29594bd3f3a62b:hover , .ubf708910504e97e39d29594bd3f3a62b:visited , .ubf708910504e97e39d29594bd3f3a62b:active { border:0!important; } .ubf708910504e97e39d29594bd3f3a62b .clearfix:after { content: ""; display: table; clear: both; } .ubf708910504e97e39d29594bd3f3a62b { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .ubf708910504e97e39d29594bd3f3a62b:active , .ubf708910504e97e39d29594bd3f3a62b:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .ubf708910504e97e39d29594bd3f3a62b .centered-text-area { width: 100%; position: relative ; } .ubf708910504e97e39d29594bd3f3a62b .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .ubf708910504e97e39d29594bd3f3a62b .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .ubf708910504e97e39d29594bd3f3a62b .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .ubf708910504e97e39d29594bd3f3a62b:hover .ctaButton { background-color: #34495E!important; } .ubf708910504e97e39d29594bd3f3a62b .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .ubf708910504e97e39d29594bd3f3a62b .ubf708910504e97e39d29594bd3f3a62b-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .ubf708910504e97e39d29594bd3f3a62b:after { content: ""; display: block; clear: both; } READ: Philippine Typhoons EssayThe winter and summer mixtures are different due to the weather conditions. For winter, Fly Ash is not used because it inhibits the set time of the concrete. Also used is accelerators to help the concrete set faster. A material called Fibermesh is used in the concrete for reinforcement and to control cracking as the concrete sets. Mr. Seymore also states that heat and moisture are the main components to make concrete set up. The concrete

Challenges the World Faces free essay sample

Each one of us endeavours to ensure a safer and better world to our children. However, in our attempt to grow rapidly, our activities and practices have an impact on our planet which is not conducive for a sustainable livelihood. There are numerous and complex challenges confronting us today which need to be addressed on a priority basis. We have polluted the atmosphere, contaminated the soil and water and destroyed the habitats of several species leading to their extinction. Climate change is now a accepted reality. As per scientists, the global average temperatures have already increased by 0. 8oC and if we continue with our current emission patterns we will continue to have rising sea levels and reseeding coastlines. Countries need to integrate their efforts and look beyond political boundaries and work towards solutions that will bring change. The entire gamut of threats that confront us today is not restricted to the environment but spreads across several sectors. We will write a custom essay sample on Challenges the World Faces or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Each country needs to identify areas which cause environmental degradation, poverty, loss of life due to war and civil strife, religious fanaticism and use all their knowledge and resources to promote education, social security, healthcare, disaster management, nuclear disarmament and efforts to resolve conflicts through dialogue. We need to educate our children to love each other and be appreciative of the other regional faiths and cultural values. Fuelled by economic growth and development, industrialisation and expansion, increasing population and rising tendency of urban migration, the global energy demand has increased dramatically and this trend expected to continue over the next several decades. At the current rate of consumption patterns, the fossil fuel reserves will be soon exhausted. There is an urgent need to identify and develop technologies to tap the renewable sources of energy. The biggest challenge that we face today is that we fail to look beyond our immediate boundaries. The need of the hour is to recognize that the only option for a better future or even any future is to reorient our minds and actions and function as citizens of planet Earth not only as Indians, Europeans or Americans or affiliated to any religious faith. We also need to have an equitable distribution and consumption of resources. It is sad that a person’s future is governed by the place where he or she is born. The developed nations can take initiatives to assist their economically challenged brethren for a better tomorrow. I believe that tomorrow is only a possibility until we make it happen. All we have is the past to learn from, beautiful minds to dream and the present to seed the future. We need to appreciate one another and to love our planet to make it a better place in the times to come. Further, it is rightly said â€Å"Be the change that you want to see in the world†. Let us all contribute in our own small ways to give our children a quality of life similar to ours if not better.