Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"AC System"”.
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Modeling, control and stability analysis of VSC-HVDC links embedded in a weak multi-machine AC system.
… with the existing longitudinal Australian power system. This thesis presents the principle design methodology to achieve robust controllers for VSCs including inner current controller, outer power and voltage controllers as well as the supplementary damping controllers for enhancing the …
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Humidity control in different building applications; restaurant and operation theatre
Air conditioning (AC) in tropical climate required dehumidification of air at a low dew point temperature to meet humidity standard. This increase the required cooling energy and heating energy is needed to raise the supply air temperature to meet the room’s design temperature. This research was …
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Hormone Stimulable Adenylyl Cyclase Activity in Ovarian Granulosa Cells of the Domestic Hen (Gallus Domesticus)
The hormone stimulable AC of chicken granulosa cells was characterized and was found to be similar to that of mammalian reproductive tissues under the conditions tested. A principal difference, however, is the stability of the enzyme. Gonadotropin dose response studies suggest that there is an …
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AC/DC power system small-signal impedance measurement for stability analysis
… research work has shown that a dc power system is small-signal stable if the Nyquist contour of product of the source impedance and load admittance satisfied the Nyquist stability criterion. Methods of extracting impedance in dc systems have been well established. However, for ac systems, …
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Design of a 380 V/24 V DC Micro-Grid for Residential DC Distribution
… at the beginning with alternating current (AC) distribution; however, due to the ease of distributing AC power over a long distance using transformers, it won against DC. Today, with the majority of electronics and appliances being used in the household using DC voltage, DC distribution is …
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Isoniazid preventative therapy penetrance at a community health centre in South Africa: a cross sectional study
Background: Tuberculosis (TB) remains a major contributor to morbidity and mortality in people living with HIV (PLHIV). The use of Isoniazid preventative therapy (IPT) has been proven to be effective and safe to reduce this burden. Despite overwhelming evidence, uptake op IPT is poor. This study …
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Implementation of power electronics in nuclear power plants: DC electrical system conceptual design and its financial analysis
… have become more competitive to traditional AC technologies. The design section of this study demonstrates the feasibility of high-level implementation of PE technology to a Nuclear Power Plant electrical system by conceptually designing a DC electrical system and comparing it to a reference …
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The design and optimization of a system using an induction motor driven pump, powered by solar panels
… of an induction motor driven water pumping system which is powered by solar panels. The system consists of a positive displacement pump, solar panels and an induction motor with a microprocessor controlled inverter. The reason that an induction motor has been chosen for the project is that …
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Stability Analysis of Three-Phase AC Power Systems Based on Measured D-Q Frame Impedances
… is of great concern for distributed power systems with a large number of regulated power converters. These converters are constant-power loads (CPLs) exhibit a negative incremental input resistance within the output voltage regulation bandwidth. In the case of dc systems, design …
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Direct current distribution systems for residential areas powered by distributed generation
Power system began its journey with DC power as pioneered by Edison. However, this was soon rivalled by AC power and ultimately DC paradigm found itself quite obsolete, against the ongoing urge to adapt in favor of higher efficiency. AC became the choice for power transfer in all areas of the power …
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Avaliação da estabilidade a pequenos sinais em sistemas CA/CC em paralelo
In Brazil, the rst DC transmission systems have traditionally been constructed as asynchronous interconnections of CA networks. However, with the start-up of the bipoles associated to the Belo Monte complex, the interconnection will take place in parallel with the AC system of the National …
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A novel backup protection scheme for hybrid AC/DC power systems
… protection scheme designed to safeguard hybrid AC/DC distribution networks against DC faults that are not cleared by the main MVDC (Medium Voltage DC) link protection. The protection scheme relies on the apparent impedance measured at the AC "side" of the MVDC link to detect faults on the DC …
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The Analysis and Study of Power System Designs for Same Polytechnic College in Tanzania
… aims to study and analyze the electrical power system and distribution for the college. Based on the projected load profile of the college and high potential for solar generation in Tanzania, several different power systems utilizing local utility AC electricity and/or photovoltaic (PV) DC …
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Improved HVdc dynamic performace via phase locking to virtual Thévenin voltage
… the input signal to a virtual estimate of ac network Thévenin equivalent voltage is introduced and evaluated for application in HVdc systems. As compared with the conventional Trans-vector PLL method, it is shown that the enhanced tracking ability of the IC-PLL improves the dynamic …
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Frontiers in alley cropping: Transformative solutions for temperate agriculture
Annual row crop systems dominate agriculture around the world and have considerable negative environmental impacts. Incremental improvements to the prevailing system have been the primary focus of efforts to reduce these negative impacts, though are likely insufficient in solving the ecological …
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Adapting to Extreme Heat: Social, Atmospheric, and Infrastructure Impacts of Air Conditioning in Megacities - The Case of New York City
… and intense in most large cities. Built-up surfaces also limit cooling mechanisms, leading to warmer conditions in cities, a phenomenon called the Urban Heat Island (UHI). This presents major challenges to reduce adverse health effects of hot weather, particularly in vulnerable populations like …
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Modeling of voltage source converter based HVDC transmission system in EMTP-RV
… include but are not limited to HVDC, Flexible AC Transmission System (FACTS) devices such as STATCOM, SSSC, UPFC and Wind generators and active filters. The VSC based HVDC system is a feasible option for bulk power transmission over long or short distances and the grid integration of renewable …
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Efficiency and Reliability Analysis of AC and 380V DC Data Centers
… a slight improvement in the power distribution system of a data center could save millions of dollars in electricity bills. Benchmarks for both AC and 380V DC data centers are developed and efficiency analyses thereof have been performed for an entire year. The efficiency of the power …
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Relamping hotel guestrooms to decrease operating costs
… was conducted at the Donaldson Brown Center in Blacksburg, Virginia with 32 hotel guests participating. Data was collected to determine light fixture usage during periods of guestroom inactivity (inactive is defined as periods after the guest had checked-in but was out of the guestroom). Two …
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Effects of Input Power Factor Correction on Variable Speed Drive Systems
The use of variable speed drive (VSD) systems in the appliance industry is growing due to emerging high volume of fractional horsepower VSD applications. Almost all of the appliance VSDs have no input power factor correction (PFC) circuits. This results in harmonic pollution of the utility supply …
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