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Thomas, Merin M. B. A. Sloan School of Management. "Intelligent supplies replenishment process." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122904.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, 2019<br>Thesis: S.M., Massachusetts Institute of Technology, Operations Research Center, in conjunction with the Leaders for Global Operations Program at MIT, 2019<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Company X is facing high cost to serve customers such as hospitals and clinics, due to irregular ordering pattern. Currently, the customer ordering process is not well planned and leads to multiple orders in a month, thereby excessive shipping and increased cost to serve. The supplies provided to customers are used for specimen collection, and the collected specimen are sent to diagnostic laboratories for analysis. Historical data on order quantities of specimen collection items (SCIs) and specimen containers returned to lab are available. This project takes advantage of the closed loop nature of the system to predict order quantities of SCIs. This project explores two replenishment strategies and compares it with the current method, through simulation.<br>The simulation models the daily consumption of SCIs at a chosen Patient Service Center (PSC), and estimates average inventory levels and the number of occurrences of stockouts for each SCI at the PSC, for varying values of parameters such as review period and safety stock levels. The two replenishment strategies are (a) constant order quantity, in which fixed replenishment quantities of SCIs are supplied every review period, and (b) predictive modelling replenishment strategy, in which the order quantities of SCIs are predicted using the data on specimen containers returned to diagnostic lab for analysis. For the latter strategy, multiple models for prediction, such as penalized regression, Classification and Regression Trees (CART) and Random Forest are used. Two parameters, the total replenishment costs and the number of occurrences of stockouts, are measured to evaluate the performance of the replenishment strategies.<br>The total cost of replenishment for constant quantity strategy is comparable to that of baseline case, whereas predictive modelling strategies have much higher cost. The constant quantity strategy with increased levels of safety stock gives best results of reducing the total cost of replenishment and minimizing the number of occurrences of stockouts.<br>by Merin Thomas.<br>M.B.A.<br>S.M.<br>M.B.A. Massachusetts Institute of Technology, Sloan School of Management<br>S.M. Massachusetts Institute of Technology, Operations Research Center
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Taylor, David Donald James. "Tools for managing intermittent water supplies." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118666.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 239-253).<br>Nearly one billion people receive water from piped networks that are not always pressurized. These intermittent water supplies (IWS) are more likely to recontaminate the distributed water than continuously-operated (or '24x7') water supplies. In addition, IWS may not provide customers with enough water. Improving the safety and sufficiency of IWS requires new management tools. This thesis proposes some such tools. Specifically, this thesis develops a suite of hydraulic, financial, and water quality models that show how each is affected by a utility's operational decisions. The proposed models are simple and do not require information about a pipe network's topology. To contextualize this work, an overview of Delhi, India's IWS is provided. The hydraulic model relates the supply pressure, supply duration, leakage rate, and volume of water received by customers. It shows that an IWS' behavior changes substantially when its customers receive the water they demand (i.e., are satisfied) and suggests why IWS exist and persist. The financial model additionally considers a utility's variable revenues and costs. It finds that low-pressure and intermittent operations maximize a utility's (short-term) gross margin and that current performance indicators encourage inequity. Where utilities are financially-motivated (e.g., performance-based contracts) the need for careful regulation and better benchmarks is demonstrated. Optimal performance penalties are proposed to ensure leak repair and high-pressure continuous water supply. The water quality model considers the conditions in which external contaminants can enter a pipe network. It shows that IWS have opposite effects on water quality during steady-state and non-steady-state operations. Both states should be regulated, modeled, and sampled. These models show that knowing the point at which customers become satisfied is crucial to managing and optimizing IWS. To better measure this point, a more accurate multi-jet water meter, which does not measure air, is designed and tested for use in IWS. The tools presented in this thesis support measuring and making progress towards global efforts such as the Sustainable Development Goals and the human right to water, promoting "safe" water supplies that are "available when needed."<br>by David Donald James Taylor.<br>Ph. D.
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Elice, Sara Jo 1979. "Chlorine demand in Haitian water supplies." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84797.
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Walpole, Mark Edward. "Intrinsically Safe (IS) Active Power Supplies." Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/15896/1/Mark_Walpole_Thesis.pdf.
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Intrinsically safe (IS) active power supplies subjected to certain transient load conditions can deliver power to a circuit at significantly higher levels than indicated on their nameplate ratings. During a transient load such as an intermittent short-circuit, energy is transferred from the power supply to the short-circuit and an electrical arc may form when the short-circuit is applied or removed. This poses a spark ignition risk as energy is transferred from the arc to the surrounding atmosphere.
Currently various International and Australian Standards define the performance requirements for IS electrical apparatus. A duly accredited laboratory is required to establish the intrinsic safety compliance of an apparatus with the Standards. It involves an assessment of the apparatus and may include testing. The assessment of the apparatus determines adequate segregation, separation, construction, and selection of components. The tests performed on the apparatus include a temperature rise test and in some cases, the sparking potential of the circuit is tested using the spark test apparatus (STA). Testing the sparking potential of active power supplies to establish compliance adds significantly to the time and costs involved in establishing compliance.
A new alternative assessment method is proposed in this report to augment or replace the testing phase of the compliance certification process for active power supplies. The proposed alternative assessment method (PAAM) is derived from a determination of the steady-state and transient output characteristics of the active power supply under consideration. Parameters such as peak output current, time constant of peak current decay, and the output voltages at these times are measured from the circuit's output characteristics. These measurements can subsequently be used to derive the topology and component values of an equivalent circuit. The resulting equivalent circuit is then considered like a linear power supply and the sparking potential can be determined using existing assessment methods.
This thesis investigates in detail the equivalent circuit of a number of direct current (DC) active power supplies whose transient output characteristics exhibit predominantly capacitive behaviour. The results of the PAAM using the equivalent circuit are then compared with results achieved using the current testing procedure with a STA.
A small sample of active power supplies is used to generate data from which a relationship between the current testing procedure and the PAAM can be established.
The PAAM developed in this research project can be used as a pre-compliance check by designers, manufacturers, or IS testing stations. A failure of this test would indicate that the active power supply's sparking energy is not low enough to be regarded as intrinsically safe. The PAAM requires fewer resources to establish a result than the STA. The benefits of a simplified spark ignition test would flow on from designers and manufacturers to end users.
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Walpole, Mark Edward. "Intrinsically Safe (IS) Active Power Supplies." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15896/.
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Intrinsically safe (IS) active power supplies subjected to certain transient load conditions can deliver power to a circuit at significantly higher levels than indicated on their nameplate ratings. During a transient load such as an intermittent short-circuit, energy is transferred from the power supply to the short-circuit and an electrical arc may form when the short-circuit is applied or removed. This poses a spark ignition risk as energy is transferred from the arc to the surrounding atmosphere. Currently various International and Australian Standards define the performance requirements for IS electrical apparatus. A duly accredited laboratory is required to establish the intrinsic safety compliance of an apparatus with the Standards. It involves an assessment of the apparatus and may include testing. The assessment of the apparatus determines adequate segregation, separation, construction, and selection of components. The tests performed on the apparatus include a temperature rise test and in some cases, the sparking potential of the circuit is tested using the spark test apparatus (STA). Testing the sparking potential of active power supplies to establish compliance adds significantly to the time and costs involved in establishing compliance. A new alternative assessment method is proposed in this report to augment or replace the testing phase of the compliance certification process for active power supplies. The proposed alternative assessment method (PAAM) is derived from a determination of the steady-state and transient output characteristics of the active power supply under consideration. Parameters such as peak output current, time constant of peak current decay, and the output voltages at these times are measured from the circuit's output characteristics. These measurements can subsequently be used to derive the topology and component values of an equivalent circuit. The resulting equivalent circuit is then considered like a linear power supply and the sparking potential can be determined using existing assessment methods. This thesis investigates in detail the equivalent circuit of a number of direct current (DC) active power supplies whose transient output characteristics exhibit predominantly capacitive behaviour. The results of the PAAM using the equivalent circuit are then compared with results achieved using the current testing procedure with a STA. A small sample of active power supplies is used to generate data from which a relationship between the current testing procedure and the PAAM can be established. The PAAM developed in this research project can be used as a pre-compliance check by designers, manufacturers, or IS testing stations. A failure of this test would indicate that the active power supply's sparking energy is not low enough to be regarded as intrinsically safe. The PAAM requires fewer resources to establish a result than the STA. The benefits of a simplified spark ignition test would flow on from designers and manufacturers to end users.
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Hu, Aiguo Patrick. "Selected resonant converters for IPT power supplies." Thesis, University of Auckland, 2001. http://hdl.handle.net/2292/3.
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For more than a century it has been known that signals and power can be transferred electromagnetically. This knowledge has motivated substantial research and development into wireless signal transmission which today is competitive with traditional conductive cabling systems. Power transfer across air gaps, however, has seen more modest development and has tended to be restricted to electric machines that have tight magnetic couplings. It is only very recently that a novel technique termed IPT (Inductive Power Transfer) has made power delivery to movable objects across large air gaps a practical reality. A typical IPT system comprises a primary power converter supplying high frequency alternating current to a conductive track loop with multiple secondary power pick-up circuits loosely coupled to it. IPT employs modern power conversion, control, and magnetic coupling techniques to achieve clean and reliable power transfer without direct electrical contact. Many practical applications have been found for IPT in materials handing, lighting, and transportation systems. One of the major constraints, however, is the primary power supply, particularly at high power levels and when power transfer over large distances is required. In this thesis selected resonant converters suitable for IPT power supplies are investigated using mathematical analysis, computer simulations and practical experiments. The basic characteristics and underlying principles of the converters are studied in order to determine their dynamic performance and power transfer capability. Special attention is given to improving existing IPT power supplies while investigating new power converters in order to achieve high efficiency and reliable operation at reduced cost. The current-fed parallel resonant converter power supply has been the basis of most commercial applications to date. It has a high efficiency and produces good voltage and current waveforms. However, both the track length that it can drive and the power level it can operate at are limited and the system may vary in frequency if the track resonant circuit and the pick-up load are not carefully designed. As a result, this supply, in its simple form, is only suitable for short track lengths and low power applications. The voltage-fed series ii quasi-resonant converter power supply controls the frequency directly and is capable of driving longer track lengths as a result of series compensation employed in the track loop. However, its voltage and current waveforms contain more harmonics, and while high efficiency may be achieved with soft switching, the condition is very dependent on the track compensation and is difficult to meet during start-up and shut down transients. In consequence, this supply is suitable for medium track lengths and medium power level applications. Improved current-fed and voltage-fed IPT power supplies are proposed in this thesis. They have the most preferred track current properties, including constant magnitude and nearly pure sine wave characteristics. Despite the circuit complexity and high system cost involved, these supplies are ideally suitable for long track lengths and high power applications. A novel converter based on free oscillation and energy injection control is also presented and shown to be capable of achieving high frequency AC power generation at very low switching frequencies while reducing the system cost. As such it is appealing for long track length, high track current, high frequency, and low voltage source applications. Finally, a very simple converter based on self-sustained oscillation without an external controller is demonstrated at low operating voltages, and a cost-effective option to overcome the start-up problems exhibited by most IPT power supplies at high voltages is shown with excellent dynamic zero voltage switching performance.<br>Whole document restricted, but available by request, use the feedback form to request access.
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Yang, Zaohong. "Novel techniques for switch-mode power supplies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/NQ38339.pdf.
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Hama-amin, Samman, and Andrejs Veldre. "Investigation of power supplies used in OSC950." Thesis, KTH, Data- och elektroteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133450.
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SammanfattningOCS950(Object Controller System 950) är en av Bombardiers produkter som hanterar säkerhetssystemet i järnvägstrafiken. Det består av olika delsystem och strömförsörjs mha nätaggregat (PSU – Power Supply Unit). I den här rapporten undersöks den befintliga PSU74-modellen samt nya switchade nätaggregat som finns på marknaden.Bakgrunden till att Bombardier vill byta ut PSU74 mot ett nytt switchat aggregat är att PSU74 har en vikt på 14 kg och tar stor plats i el-skåp. Ett swichat nätaggregat väger ungefär 1,5 kg och är så pass kompakt att det tar litet utrymme i el-skåpet.Bombardier har medvetet väntat med att gå över till SMPS eftersom tillförlitlighet blir ett problem. Detta problem kan lösas mha redundanta kopplingar. MTBF är den största utmaningen vid övergång till SMPS. MTBF beräkningar för redundanta kopplingar presenteras i rapporten och resultatet visar att ju fler enheter ett system innehåller desto mindre blir MTBF-värdet.I faktainsamlingsdelen beskrivs och förklaras olika viktiga begrepp för att underlätta förståelse av rapporten. MTBF, linjära och switchade nätaggregat är bara några begrepp som tas upp.En studie av PSU74 och en lista över dess viktiga egenskaper presenteras, det är en utgångspunkt för kravspecifikation för nytt switchade nätaggregat. Vissa egenskaper som prioriteras är MTBF, in-och utspänning, vikt och drifttemperatur mm.Ett enkelt kretsschema konstrueras och visar principen för redundant koppling. Kravspecifikationen finns i ett tabellformat. De flesta egenskaper är definierade men vissa är ej fastställta. Bombardier definierar värde på dessa egenskaper efter diskussion med potentiella tillverkare.En alternativ lösning presenteras där ett uppvärmningsförslag av el-skåp läggs fram. Denna metod kan bredda urval av SMPS på marknaden. En omfattad undersökning av marknaden genomförs där olika modeller analyseras baserade på kravspecifikationer. En utmaning är omgivningstemperaturen eftersom de flesta SMPS tål – 25°C minimum drifttemperatur. Några modeller som uppfyller kriterierna undersöks noggrant och systematiskt. Analys av utvalda SMPS utförs och slutsatser presenteras där för- och nackdelar med respektive modell lyfts fram. Det konstanteras att modell från Cosel TUFS300F28 är ett bra alternativ för ersättning av PSU74.
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Dancy, Abram P. (Abram Paul). "Power supplies for ultra low power applications." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10069.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.<br>Includes bibliographical references (p. 101-103).<br>by Abram P. Dancy.<br>M.Eng.
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Tebb, David W. "Transistorised induction heating power supplies using MOSFET's." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/12595.
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A prototype has been designed and constructed that has fed 3kW into a Commercial workcoil at 150 kHz. Another lower power inverter has been built. This was developed with ease of production in mind to aid the transfer of technology to the sponsoring company. The company have adopted this unit and are manufacturing it. The thesis reviews induction heating power supplies with emphasis on those able to operate above 100 kHz. Members of the MOSFET family are described and critically assessed for the application Prototypes of various configurations have been constructed and experience of these has led to the choice of current fed topology as the best for the application. The design and layout of a three phase current fed full bridge inverter that can feed 5 kW into an industrially relevant coil at 400 kHz and a single phase 2.5 kW version are described. Results of tests carried out on the units are presented. A microprocessor system has been selected which has been used for closed loop control of power, temperature and housekeeping tasks such as the supervision of interlocks.
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Popely, Deborah R. "Strategies to Maintain Adequate Hotel Water Supplies." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5931.
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Hotel guests can use 2 to 3 times more water than community residents. Hotels are water-intensive businesses, and water scarcity presents a pressing problem for managers who rely on an uninterrupted supply of water to meet guests' needs and maintain profitability. Using the resource-based view (RBV) as a conceptual framework, the purpose of this qualitative multiple case study was to explore strategies that hotel managers used to successfully maintain adequate water supplies in the Spanish Canary Islands, an historically arid site and a tourism destination. Data were collected from semistructured interviews and hotel water usage reports. Yin's 5-step approach of examining, categorizing, tabulating, testing, and recombining evidence to draw conclusions guided the data analysis. Four key themes emerged from the findings: value water as a strategic business resource, mitigate risks of natural resources scarcity, promote water efficiency and conservation, and sustain supplies through corporate water stewardship. This study may contribute to positive social change by illuminating processes that hotel managers, employees, guests, and partners, can take to improve environmental stewardship and align their practices with sustainable water governance.
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Wong, Fu Keung, and n/a. "High Frequency Transformer for Switching Mode Power Supplies." Griffith University. School of Microelectronic Engineering, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050211.110915.
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A power supply is an essential part of all electronic devices. A switching mode power supply is a light weight power solution for most modern electronic equipment. The high frequency transformer is the backbone of modern switched mode power supplies. The skin effect and proximity effects are major problems in high frequency transformer design, because of induced eddy currents. These effects can result in transformers being destroyed and losing their power transferring function at high frequencies. Therefore, eddy currents are unwanted currents in high frequency transformers. Leakage inductance and the unbalanced magnetic flux distribution are two further obstacles for the development of high frequency transformers. Winding structures of power transformers are also a critical part of transformer design and manufacture, especially for high frequency applications. A new planar transformer with a helical winding structure has been designed and can maintain the advantages of existing planar transformers and significantly reduce the eddy currents in the windings. The maximum eddy current density can be reduced to 27% of the density of the planar transformer with meander type winding structure and 33% of the density of the transformer with circular spiral winding structure at an operating frequency of 1MHz. The voltage ratio of the transformer with helical winding structure is effectively improved to 150% of the voltage ratio of the planar transformer with circular spiral coils. With the evenly distributed magnetic flux around the winding, the planar transformer with helical winding structure is excellent for high frequency switching mode power supplies in the 21st Century.
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Cleaver, Frances. "Community management of rural water supplies in Zimbabwe." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321023.
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Miwa, Brett Andrew. "Interleaved conversion techniques for high density power supplies." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12763.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.<br>Includes bibliographical references (leaves 188-193).<br>by Brett Andrew Miwa.<br>Ph.D.
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Amarasinghe, Kanishka A. "Resonance mode power supplies with power factor correction." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/23672.
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There is an increasing need for AC-DC converters to draw a pure sinusoidal current at near unity power factor from the AC mains. Most conventional power factor correcting systems employ PWM techniques to overcome the poor power factor being presented to the mains. However, the need for smaller and lighter power processing equipment has motivated the use of higher internal conversion frequencies in the past. In this context, resonant converters are becoming a viable alternative to the conventional PWM controlled power supplies. The thesis presents the implementation of active power factor correction in power supplies, using resonance mode techniques. It reviews the PWM power factor correction circuit topologies previously used. The possibility of converting these PWM topologies to resonant mode versions is discussed with a critical assessment as to the suitability of the semiconductor switching devices available today for deployment in these resonant mode supplies. The thesis also provides an overview of the methods used to model active semiconductor devices. The computer modelling is done using the PSpice microcomputer simulation program. The modifications that are needed to the built in MOSFET model in PSpice, when modeling high frequency circuits is discussed. A new two transistor model which replicates the action of a OTO thyristor is also presented. The new model enables the designer to estimate the device parameters with ease by adopting a short calculation and graphical design procedure, based on the manufacturer's data sheets. The need for a converter with a high efficiency, larger power/weight ratio, high input power factor with reduced line current distortion and reduced cost has led to the development of a new resonant mode converter topology, for power processing. The converter presents a near resistive load to the mains thus ensuring a high input power factor, while providing a stabilised de voltage at the output with a small lOOHz ripple. The supply is therefore ideal for preregulation applications. A description of the modes of operation and the analysis of the power circuit are included in the thesis. The possibility of using the converter for low output voltage applications is also discussed. The design of a 300W, 80kHz prototype model of this circuit is presented in the thesis. The design of the isolation transformer and other magnetic components are described in detail. The selection of circuit components and the design and implementation of the variable frequency control loop are also discussed. An evaluation of the experimental and computer simulated results obtained from the prototype model are included in the presentation. The thesis further presents a zero-current switching quasi-resonant flyback circuit topology with power factor correction. The reasons for using this topology for off-line power conversion applications are discussed. The use of a cascoded combination of a bipolar power transistor and two power MOSFETs i~ the configuration has enabled the circuit to process moderate levels of power while simultaneously switching at high frequencies. This fulfils the fundamental precondition for miniaturisation. It also provides a well regulated DC output voltage with a very small ripple while maintaining a high input power factor. The circuit is therefore ideal for use in mobile applications. A preliminary design of the above circuit, its analysis using PSpice, the design of the control circuit, current limiting and overcurrent protection circuitry and the implementation of closed-loop control are all included in the thesis. The experimental results obtained from a bread board model is also presented with an evaluation of the circuit performance. The power factor correction circuit is finally installed in this supply and the overall converter performance is assessed.
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Chen, Rengang. "Integrated EMI Filters for Switch Mode Power Supplies." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/25992.
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Because of the switching action, power electronics converters are potentially large EMI noise sources to nearby equipment. EMI filters are necessary to ensure electromagnetic compatibility. Conventional discrete EMI filters usually consist of a large number of components, with different shapes, sizes and form factors. The manufacturing of these components requires different processing and packaging technologies, of which many include labor-intensive processing steps. In addition, due to the parasitics of discrete components, high-frequency attenuation of the filter is reduced and the effective filter frequency range is limited. As a result, discrete EMI filters are usually bulky, high profile, and have poor high-frequency performance. With an aim to solving these issues, this study explores the integration of EMI filters. The goal is to achieve a smaller size, lower profile, better performance and reduced fabrication time and cost via structural, functional and processing integration.
The key technology for EMI filter integration is planar electromagnetic integration, which has been a topic of research over the last few years. Most of the previous applications of this technology for switch mode power supplies (SMPSs) were focused on the integration of high frequency power passive electromagnetic components, such as HF transformers, resonant/choke inductors and resonant/blocking capacitors. Almost no work has been done on the subject of EMI filter integration. Since the major function of EMI filters is to attenuate, instead of propagate, energy at the switching frequency and its harmonics, the required technology and design objectives are very different from those of other components. High-frequency modeling of the integrated structure becomes more essential since the high-frequency performance becomes the major concern. New technology and a new model need to be developed for EMI filter integration.
To bridge this gap between existing technologies and what is necessary for EMI filter integration, this dissertation addresses technologies and modeling of integrated EMI filters. Suitable integration technologies are developed, which include reducing the equivalent series inductance (ESL) and equivalent parallel capacitance (EPC), and increasing, instead of reducing, the high frequency losses. Using the multi-conductor lossy transmission-line theory, a new frequency domain model of integrated LC structure is developed and verified by experimental results. Through detailed electromagnetic analysis, the equations to calculate the required model parameters are derived. With the developed frequency domain and electromagnetic model, the characteristic of integrated LC modules can be predicted using geometry and material data.
With the knowledge obtained from preliminary experimental study of two integrated EMI filter prototypes, a technology is developed to cancel structural winding capacitance of filter inductors. This can be realized by simply embedding a thin conductive shield layer between the inductor windings. With the resultant equivalent circuit and structural winding capacitance model, optimal design of the shield layer is achieved so that EPC can be almost completely cancelled. Applying this technology, an improved integrated EMI filter with a much simpler structure, a much smaller size and profile, and much better HF performance is designed, constructed and verified by experiment. The completed parametric and sensitivity study shows that this is potentially a very suitable technology for mass production.
The integrated RF EMI filter is studied, as well. Its frequency domain model is developed based on multi-conductor lossy transmission-line theory. With the model parameters extracted from the finite element analysis (FEA) tool and the characterized material properties, the predicted filter characteristic complies very well with that of the actual measurement. This model and modeling methodology are successfully extended to study the RF CM&DM EMI filter structure, which has not been done before. To model more complicated structures, and to study the interaction between the RF EMI filter and its peripheral circuitry, a PSpice model with frequency dependent parameters is given.
Combining the structural winding capacitance cancellation and the integrated RF CM&DM EMI filter technologies, a new integrated EMI filter structure is proposed. The calculation results show that it has the merits of the two employed technologies, hence it will have the best overall performance.<br>Ph. D.
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Zhang, Wei. "Integrated EMI/Thermal Design for Switching Power Supplies." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36672.
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This work presents the modeling and analysis of EMI and thermal performance for switch power supply by using the CAD tools. The methodology and design guidelines are developed.
By using a boost PFC circuit as an example, an equivalent circuit model is built for EMI noise prediction and analysis. The parasitic elements of circuit layout and components are extracted analytically or by using CAD tools. Based on the model, circuit layout and magnetic component design are modified to minimize circuit EMI. EMI filter can be designed at an early stage without prototype implementation.
In the second part, thermal analyses are conducted for the circuit by using the software Flotherm, which includes the mechanism of conduction, convection and radiation. Thermal models are built for the components. Thermal performance of the circuit and the temperature profile of components are predicted. Improved thermal management and winding arrangement are investigated to reduce temperature.
In the third part, several circuit layouts and inductor design examples are checked from both the EMI and thermal point of view. Insightful information is obtained.<br>Master of Science
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Wong, Fu Keung. "High Frequency Transformer for Switching Mode Power Supplies." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367650.
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A power supply is an essential part of all electronic devices. A switching mode power supply is a light weight power solution for most modern electronic equipment. The high frequency transformer is the backbone of modern switched mode power supplies. The skin effect and proximity effects are major problems in high frequency transformer design, because of induced eddy currents. These effects can result in transformers being destroyed and losing their power transferring function at high frequencies. Therefore, eddy currents are unwanted currents in high frequency transformers. Leakage inductance and the unbalanced magnetic flux distribution are two further obstacles for the development of high frequency transformers. Winding structures of power transformers are also a critical part of transformer design and manufacture, especially for high frequency applications. A new planar transformer with a helical winding structure has been designed and can maintain the advantages of existing planar transformers and significantly reduce the eddy currents in the windings. The maximum eddy current density can be reduced to 27% of the density of the planar transformer with meander type winding structure and 33% of the density of the transformer with circular spiral winding structure at an operating frequency of 1MHz. The voltage ratio of the transformer with helical winding structure is effectively improved to 150% of the voltage ratio of the planar transformer with circular spiral coils. With the evenly distributed magnetic flux around the winding, the planar transformer with helical winding structure is excellent for high frequency switching mode power supplies in the 21st Century.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Microelectronic Engineering<br>Full Text
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Harty, Michael David. "Statistical process control as a tool for expert system diagnostics." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/24853.
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Santos, William O. "An analysis of the prediction accuracy of the U.S. Navy repair turn-around time forecast model." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FSantos.pdf.
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Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2003.<br>Thesis advisor(s): Robert A. Koyak, Samuel E. Buttrey. Includes bibliographical references (p. 55). Also available online.
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Al-Ansary, Hany A. "Investigation and improvement of ejector-driven heating and refrigeration systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/36540.
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Hu, Lihua. "The application of reactive power compensation to ac electrified railway systems." Thesis, Staffordshire University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282965.
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Wong, Wilson Kia Onn. "To what extent and why has the structure of the global automotive components industry changed since the 1980s? : an analysis of the global tyres, seats, constant velocity joints, brakes and automotive semiconductor sectors." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648395.
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Maria, José Michelle. "Optimization of Production Flow at Eco Supplies Solar AB." Thesis, KTH, Industriell produktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102530.
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In this competitive world with rapid growth of markets, the main goal of any company is to attain an edge over its competitors. In order to achieve this goal a company has to continually improve its process and eliminate the wastes in the process while not compromising on the quality of the product and customer satisfaction. Though Eco Supplies Solar AB is one of the largest producers of Photovoltaic solar modules in Scandinavia, the need for improvement is vital to match with growing requirements and to maintain its position in the market. This master thesis was done for Eco Supplies Solar AB, so as to help them identify the waste along their value stream process. The project was divided into three phases. The first phase of the project was to map and analyze the plant layout as well as analyze the worker movement. This helped to understand the various movements through the entire process of production and the associated distances and time. The second phase of the thesis was the execution of the Value Stream Mapping. For this purpose the entire production process was walked through and through several interviews the data was collected. The current state value stream map gave a one page static picture of the key areas of waste within the process and to suggest necessary changes so as to improve the efficiency. The suggested changes are implemented and the future state map is drawn. The results from the current state and future state map are calculated theoretically and analyzed. The third phase is the use of Simulation to understand the behavioral effects of each the processes and to determine the overall change in productivity if the changes are implemented. It is difficult to implement changes in a production plant that works continuously for 24 hours. That would interrupt production and also lead to large costs. The easier and most optimal solution to implement changes, understand the behavior of each process before and after the changes and to analyze the changes is to run a simulation model of the current and future state. The simulation is done using Extend Sim software and the results are analyzed further. The main aim of the thesis was to analyze the current plant layout and the product process and develop a methodology to identify visualize and measure the wastes in the production process of Photovoltaic solar modules.
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Hu, Zhiyuan. "A multiplexed feedback solution for isolated digital power supplies." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28530.
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As digital power supply became a significant market opportunity, manufacturers started looking at ways to control the system cost by reducing components and their technical requirements.
This thesis proposes a multiplexed digital feedback solution for isolated digital power supply systems. Several digital isolators used in existing applications can be reduced to one. The data transmission speed is greatly reduced. The communication protocol is DC-balanced; therefore pulse-transformer type digital isolators can be used resulting in further lower cost. The proposed solution also improves output accuracy over existing solutions.
Presentation of the proposed system will be in three parts: architecture, protocol, and Piece-wise Linear Feedback method.
Both theoretical analysis and practical implementation will be discussed, and the simulation results included support the theoretical analysis. A prototype board was built and its performance is promising.
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Burgers, Alfonso. "The water supplies and related structures of Roman Britain." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/30789.
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Information is provided on the remains of aqueducts, wells, Roman baths, drains, pipes, springs and tanks, from 807 sites in Roman Britain (fortresses, forts, towns, small towns, settlements and villas). The introduction of running water supplies and baths had considerable social implications, for urban and rural communities. Aqueducts are the most intensively researched water-related structure of Roman date; evidence from Britain is presented in detail. Particular attention focuses on unresolved structural problems (Leicester, Lincoln). Wells were also important for water supply at all site types, especially for domestic use; possible religious aspects are also discussed. The layout of bath buildings is reviewed, and the provision of drains and sewers. Distributions of all the various water-related structures, based on the archaeological record, are evaluated. Several points emerge from this analysis, i.e. a number of settlements should be reclassified based on their possession of public baths or running water supplies. Generally, these systems are poorly understood, partly through concentration of past fieldwork on monumental and domestic structures (areas outside buildings have rarely been investigated in detail). Britain's high annual rainfall has tended to diminish the importance attached by scholars to water-related features. There has been a general reluctance to discuss water supply and baths in studies of urban and villa development. These factors have tended to obscure their relevance both socially and technically, resulting in a lack of appreciation of the complexities surrounding water supply. An attempt is made to quantify the labour organisation and costs of well and aqueduct construction, to show the impressive scale of some Romano-British ventures. It is concluded that water-related features are generally under-represented in the archaeological record, compared to the number of known sites. This can only be corrected by considerable additional fieldwork and re-evaluation of existing information.
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Barber, John. "The rationalisation of drinking water supplies for pig housing." Thesis, University of Plymouth, 1992. http://hdl.handle.net/10026.1/2463.
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This study consisted of a series of experiments which investigated the water use of growing/finishing pigs (25-90 kg), newly weaned pigs (5- 12 kg) and gestating sows. Drinker type was found to affect water use in growing pigs. For example significantly more water (28 %) was used from Mono-flo nipple drinkers than Arato bite drinkers (P<0.01). For all classes of pigs studied water use was significantly increased by increasing the water delivery rate. The percent increase in water use over the extremes of water delivery rate tested in individual trials were respectively: ration fed growing pigs, 105 % (300-900 cm³ /min P<0.001); ad libitum fed growing pigs, 52% (200-1100 cm³/min P<0.01); gestating sows, 25% (500-2500 cm³/min P<0:01); and newly weaned pigs 109% (175-700 cm³ /min P<0.001). In newly weaned piglets, increasing the water delivery rate from 175 to 700 cm³/min resulted in a significant increase in feed intake (44 g/piglet/day, P<0.001) and growth rate (37 g/piglet/day, P<0.01). For growing pigs (27-55 kg), a relationship was established between water intake, feed intake and liveweight, from which it could be hypothesised that the pig had a limit to daily volumetric intake. This was found to be 12.0 ±1.2 % of liveweight. When feed intake was restricted, water intake increased to maintain the 12% volumetric limit. This hypothesis was validated from other published work extending the weight range to 105 kg. Evidence was produced indicating that newly weaned pigs also have a constant volumetric daily limit. It is suggested that in cases where feed intake needs to be restricted, water intake could be manipulated in order to limit feed intake. This would permit the wider use of ad lib feeding systems and the welfare benefits these allow. The water use of a grower/finisher unit was modelled according to a 12 % volumetric limit and the factors affecting water intake and wastage. The water intake of grower/finisher pigs was predicted using this model. This enabled the percentage of water wasted by different drinker types and delivery rates to be estimated. For wet fed pigs, increasing the water to feed ratio from 1.63:1 to 3. 25: 1 significantly increased feed digestibility (P<0. 05). As many experiments conducted to evaluate the digestible energy of feeds may have used low feed to water ratios (generally around 2:1) it is suggested that many of these studies have attributed incorrect nutritional values to raw materials used in diets for pigs.
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Pardon, Ojeda Mauricio. "Treatment of turbid surface water for small community supplies." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/2191/.
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Shepherd, Kim. "Health implications of microbial contamination of private water supplies." Thesis, University of Sunderland, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310618.
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Worthington, D. R. E. "The cooling of electronic power supplies by natural convection." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380691.
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Bartram, Jamie. "Optimising the monitoring and assessment of rural water supplies." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320994.
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Mac-Lean, Andres (Andres Felipe) 1959. "Introducing the concept of office supplies superstores in Chile." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9186.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management, 2000.<br>Also available online on DSpace at MIT.<br>Includes bibliographical references (leaf 88).<br>The concept of office supplies superstores doesn't exist in Chile. This thesis defines an entry strategy for this concept in Chile. The thesis is divided into two areas: 1. An analysis of the office supply industry in the USA mainly represented by Staples. This work is based on the application of the Delta Model. This part includes an analysis of the environment, a detail analysis of Staples (mission, organization, the store, business strategy, operations, marketing, expansion, web, acquisition and financial analysis) and a structural analysis of the industry (Porter's five-forces model.) 2. The second part of the thesis consists of a Business Plan to introduce such model in Chile by evaluating the following factors: the market, the competition, investment required, distribution strategy, operational plan, sales and marketing, exit strategies, risks and financial projections.<br>by Andres Mac-Lean.<br>M.B.A.
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Stevens, Chad Howard 1980. "Assessment of desalination treatment processes for future water supplies." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/85745.
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Hinchliffe, Stephen. "Solid-state high-frequency electric process heating power supplies." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/32518.
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A detailed critical review has been made of both solid state power devices and circuit topologies with emphasis on their application to high frequency electric process heating power supplies operating between 3and 30 MHz. A number of prototype units have been designed and constructed and their suitability for high frequency induction heating and dielectric heating applications investigated. Desirable qualities being robustness, tolerance to load mismatch, ease of design, simplicity and cost of constituent components as compared with present day valve equipment The experience gained in these investigations has resulted in the choice of the power MOSFET as the most appropriate device and Class E amplifier as being the most applicable circuit topology for the generation of RF power for high frequency electric process heating applications. A practical and theoretical study has been made of the limitations of the power MOSFET as a high frequency switching device. The effect of source feedback on the switching speed of T03 packaged devices has been investigated by the addition of a second source terminal in a specially modified T03 package. Novel drive circuits have been developed enabling high frequency switching of both power and RF MOSFETs. These have been employed in inverters operating at 3.3 MHz at power levels up to 600 W and at frequencies between 7 and 27 MHz at power levels over 100 W, with conversion efficiencies of up to 95%.
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Van, Wyk Ashwill Louis. "Effects of voltage unbalanced supplies on energy-efficient motors." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11523.
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Eskom DSM has recently introduced an Energy Efficiency (EE) Motor program, which provides incentives to industrial customers to retrofit standard motors with EE motors. The main objective of the program is to realize energy savings through the replacement of standard (STD) induction motors with higher efficiency EE motors. Although the principle of the program is correct, there are several significant power quality and performance issues with EE motors.These issues need to be thoroughly investigated in order to achieve the overall energy saving objectives of program.
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Garcia, Claudett Nicolas, Fernández Renato Lastarria, Zamudio Luz Stefanny Lizana, and Lanatta Nicolas Sifuentes. "Implementación de Utilibro." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626656.
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El presente proyecto sobre útiles escolares o artículos de oficina nos muestra la viabilidad de su ejecución, este proyecto está dirigido a padres de familia y personas que laboran en oficinas que viven, trabajan o radican en la zona 7 de Lima Metropolitana, nos estamos refiriendo a los distritos de San Borja, San Isidro, Miraflores, Surco y La Molina. Nos hemos enfocado en ese target, debido a que según nuestras investigaciones se les hace muy complicado la compra de útiles escolares a inicios de cada año escolar a los padres de familia, y por otro lado a las personas que laboran en oficina se les hace complicado comprar distintos artículos por su falta de tiempo, ambos coinciden en que es tedioso hacer estas comprar por el tiempo, la comodidad, los precios, entre otros. Es por eso que Utilibro ofrece útiles escolares o artículos de oficina a unos precios menores a los del mercado, adicionando un servicio de delivery para simplificar la vida de los consumidores.<br>This project about office and school supplies shows the viability of its execution. It is focused on both parents with children aged 6 to 17 and office men that live in the districts of San Borja, San Isidro, Miraflores, Santiago de Surco and La Molina from Metropolitan Lima. We targeted those segments because our investigation concluded that it is difficult for parents to acquire all the school supplies required at the beginning of the academic year and office men usually don’t have the time to invest in buying supplies for their workplace. Both segments coincide in the fact that it is tedious to get those supplies for a matter of time, confort, pricing, etc. That’s why Utilibro offers the solution by selling both school and office supplies at a lower cost and delivers the orders to the place designed by our customers.<br>Trabajo de investigación
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Ho, Yan-cheung Robin. "An appraisal on the water supplies and sewage disposal management by various governmental departments : Water Supplies Department, Environmental Protection Department, and Drainage Services Department /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21301906.
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Zhang, Yang. "Digital control in modular masterless multi-phase microprocessor power supplies." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273731.
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Barrott, Lisa. "Evaluation of novel disinfection methods for small community water supplies." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340784.
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Hallworth, Michael. "Digital peak current mode control of switched-mode power supplies." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602418.
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Peak current mode control is a popular method of SMPS control due the inherent cycle-by- cycle current limiting, feed-forward control and current sharing ability it provides. However, the subharmonic oscillations which plague peak current mode control must be removed using slope compensation. Until the work presented in this thesis, there have been no true digital implementations of peak current mode control due to the difficulties associated with implementing a digital form of slope compensation. This thesis introduces a complete digital peak current mode converter which uses a novel method of digital slope compensation to remove the subharmonic oscillations observed when using peak current mode control. The digital implementation of peak current mode control is applied to a Buck converter design example which directly compares the proposed digital scheme with an equivalent analog scheme. Exact analytical design equations are derived which allow a specified crossover frequency and phase margin to be achieved concurrently. The l6W Buck converter design example compares the digital peak current mode controlled converter with an analog converter designed to the same specification and tested on the same power stage PCB. The detailed steady state, transient and frequency response results from the hardware experimentations show excellent correlation with the MATLAB simulated converter and are in good agreement with the equivalent analog converter. The crossover frequency is specified as 15kHz and is measured as 14.71kHz on the proposed digital converter with a measured phase margin only 5' less than the specification. The results confirm that the operation of the proposed digital peak current mode control scheme is functionally similar to analog peak current mode control.
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Beatty, Debra Ann Kemnitz. "Simulation of a family of DC-to-DC power supplies." Honors in the Major Thesis, University of Central Florida, 1995. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/137.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.<br>Bachelors<br>Engineering<br>Electrical Engineering
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Al-Qassemi, Rasha A. "Aspects of behaviour of Pseudomonas aeruginosa associated with water supplies." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288687.
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Williams, Richard. "High frequency multi-element transformers for switched-mode power supplies." Thesis, University of Bristol, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283625.
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Farkas, Thomas. "A scientific approach to EMI reduction in switching power supplies." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/35360.
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Slamdien, Muammar. "Mitigating interference from switch-mode power supplies in sampling receivers." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2513.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017.<br>This thesis reports on the research and development of techniques applied to mitigate interference from switch-mode power supplies in sampling receivers and also more specifically for FMCW radar receiver applications. During the system testing phase of an FMCW Radar at Reutech Radar Systems (RRS), it was found that a large false target was emerging on the Range-Doppler Map (RDM). It was concluded that the problem was originating from interference caused by the switch-mode power supplies (SMPS), which supply DC power to the radar receiver subsystem. This then created the need for a new DC power supply, which is able to minimize the interference, as well as, mitigate the effects of the interference caused by the switching of the power supply. The mitigation techniques and power supply development was divided four main sections, namely, research, simulation, design and evaluation. The research involved obtaining background information on sampling receivers, sampling theory, Range-Doppler Processing, switch-mode power supplies, their effects and mitigation thereof. In the simulation phase, the research was utilised to simulate the various interference mitigation techniques. A power supply PCB was then designed in the design phase to practically illustrate the techniques being utilised. Lastly, during evaluation, this PCB was evaluated against the criteria set out in the research phase. The results demonstrated that the technique of synchronising the PWM clock to the Sampling frequency and SRF yielded a significant reduction in the SMPS noise on the Range-Doppler Map.
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Manyage, Marubini J. "Operation of induction machines in the presence of unbalanced supplies." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/8753.
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Includes bibliographical references.<br>Three-phase induction machines are widely used in South Africa for industrial, commercial and residential applications because of their simple construction and low maintenance. The manufacturers design these motors to provide their nameplate ratings when supplied with balanced sinusoidal voltages. However, the power system experiences unbalanced voltages, overvoltages, undervoltages, etc, which are seen at the motor terminals. The South African Electricity Supply Utility (Eskom) supplies the commercial and industrial systems with a line voltage range of 400V +- 10%. An Induction motor rated at 380V or 400V will therefore experience overvoltages or undervoltages depending on the location of the motor from the supply. Besides overvoltages and undervoltages, unbalanced voltages exist on the power system. The tolerable level of voltage unbalance on the South African three-phase networks is 2%, and may be up to 3% in the rural areas. In practice, induction motors experience a combination of overvoltages or undervoltages with unbalanced voltages. This affects motor life. NEMA has done research on induction motors operating under unbalanced voltages. They defined voltage unbalance and produced a derating curve, assuming the average voltage applied to the motor is equal to the rated voltage. The EEC has another definition of voltage unbalance based on the positive and negative sequence voltages. The IEC definition is referred to as the true definition. Two formulas that approximate the true definition also exist. An analysis was done in order to understand the implications of using these definitions of voltage unbalance in the South African power system. It was found that the NEMA definition and the true definition do not differ significantly below a 5% unbalance. in order to estimate motor life when a motor is supplied with unbalanced voltages, in combination with over or undervoltages, electrical and thermal models were developed to predict the temperature. The electrical model was based on the positive and negative sequence equivalent circuits. The thermal model used, separated stator and rotor thermal circuits. The thermal parameters were obtained from simple tests rather than from motor design data. The predicted temperature values agree closely to the measured values. The interaction between the electrical model, thermal model and the thermal ageing equation were used to estimate motor life when the motor is supplied with unbalanced voltages, in combination with over or undervoltages. Motor life is reduced when the operating temperature exceeds the rated. In order to restore motor life, new derating curves were developed since the NEMA derating curve is limited to rated average voltage. Motor life can be restored by applying the new derating curves developed here.
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Theodore, Susan Mack 1958. "Reduction of electromagnetic interference in multiple switched mode power supplies." Thesis, The University of Arizona, 1995. http://hdl.handle.net/10150/278520.
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A method to reduce Electromagnetic Interference (EMI) of multiple switching waveforms by harmonic cancellation is presented. The waveforms considered are input currents generated by 'n' Discontinuous Mode (DCM) Flyback Switched Mode Power Supplies (SMPS) that share a common source. The waveforms are modeled as ideal triangular waveforms and a Fourier analysis is performed to determine the phase relationship, θ, that minimizes the EMI. The combined EMI is minimum when θ=360°/n and maximum when θ=0°. A system of two DCM Flyback SMPS is designed in such a way that both 0° and 180° phase shifts between input current waveforms are possible. In both cases EMI filters are designed to meet EMI standard MIL-STD-461. The system is simulated and constructed and the experimental results are presented. These results demonstrate the accuracy of the modeled waveform and the reduction of conducted EMI when optimal phasing is achieved.
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Louw, Andre. "Investigating the benefits of using selected lean techniques at a South African exhaust manufacturer-a case study." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1518.
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This study investigates the implementation of supermarket-based scheduling of parts at a South African exhaust manufacturing plant. The study firstly investigates the requirements the manufacturer had to contend with in ensuring a valuable contract was won. The nature of the contract is such that it warrants building of a new facility. The design of the facility and the manufacturing processes is of importance as some Lean techniques are employed during these early stages. The research takes the form of a case study and data is collected mainly through interviews with staff, but also from direct observations on the shop-floor. Interviews were conducted with: - key project leaders responsible for the original design and commissioning of the facility; - production managers and technical staff currently operating the plant; and - shop-floor personnel involved in daily production and logistics operations within the plant. The as-built facility and procedures are compared with literature found on the topic of Lean manufacturing. Various findings are recorded, both on conforming to and not conforming to typical Lean theory. Potential changes are suggested in the following areas: - a Pull strategy is proposed to coincide with the appointment of a so-called pacemaker station; - a pacemaker would need to be further supported by a production leveling strategy; - although quality delivered to the customer is reported as very high, potential improvements are still possible by introducing an "at source" approach to reduce rework; and - finally, a Total Productive Maintenance (TPM) program will serve to reduce downtime even further.
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Rothsching, Norman. "The effect of shaft stiffness on the performance of the ice hockey slap shot." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ43940.pdf.
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Muzzy, Sarah Burnett. "Consumerism and the transition to motherhood : a project based upon an independent investigation /." View online, 2007. http://hdl.handle.net/10090/7585.
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