Pembinaan enjin pencariodits (online database for information technology student) di Politeknik Ungku Omar

Kajian ini adalah berkisar tentang pembelajaran rnelalui pencarian maklumat pembelajaran menggunakan enjin pencari. Terdapat banyak jenis enjin pencari yang popular di dalam internet seperti Yahoo, Google, Altavista, Infoseek dan Excite. Namun begitu, enjin pencari tersebut mempamerkan keputusan carian secara meluas dan ada kalanya tidak berkaitan dengan carian topik. Oleh sebab itu, pengguna internet perlu mempunyai kemahiran untuk melakukan carian bagi mendapatkan keputusan carian yang bersesuaian dengan carian ke atas topik. Pengguna internet juga mesti mengkaji dan mempraktikkan beberapa teknik untuk memperincikan keputusan carian dalam memperolehi maklumat yang relevan. Alternatif kepada masalah ini adalah membangunkan enjin pencari ODITS untuk kegunaan pelajar. Di dalam enjin pencari ini, aspek-aspek yang dikaji adalah rekabentuk antaramuka, penggunaan enjin pencari dalam mendapatkan bahan pembelajaran, pembelajaran kendiri dan rujukan tambahan untuk kegunaan pelajar. Seramai 28 orang pelajar Diploma Teknologi Maklumat semester III dipilih sebagai responden. Instrumen kajian yang digunakan adalah borang soal selidik. Ia dibahagikan kepada 5 bahagian iaitu bahagian A (demografi), bahagian B (bahan pembelajaran), bahagian C (pembelajaran kendiri) dan bahagian E (rujukan tambahan). Data-data yang diperolehi dianalisis dengan menggunakan perisian SPSS (Statistical Packages for the Social Sciences). Data-data dipaparkan di dalam bentuk min, peratusan dan sisihan piawai. Keputusan dibentangkan dalam bentuk jadual dan rajah. Dapatan kajian menunjukkan bahawa rekabentuk antaramuka enjin pencari ODITS adalah menarik dan enjin pencari ODITS boleh dijadikan bahan pembelajaran. Selain itu, pembelajaran kendiri dapat dilaksanakan dan penggunaan enjin pencari ini boleh dijadikan sebagai rujukan tambahan kepada para pelajar. Akhir sekali, beberapa cadangan untuk kajian lanjutan telah dikemukakan

An adaptive digital controller for switching dc-dc converters

Version of RecordPublishe

An Update on Power Quality

Power quality is an important measure of fitness of electricity networks. With increasing renewable energy generations and usage of power electronics converters, it is important to investigate how these developments will have an impact to existing and future electricity networks. This book hence provides readers with an update of power quality issues in all sections of the network, namely, generation, transmission, distribution and end user, and discusses some practical solutions

An Inductor Emulator Approach to Peak Current-mode Control in a 4-Phase Buck Regulator

abstract: High-efficiency DC-DC converters make up one of the important blocks of state-of-the-art power supplies. The trend toward high level of transistor integration has caused load current demands to grow significantly. Supplying high output current and minimizing output current ripple has been a driving force behind the evolution of Multi-phase topologies. Ability to supply large output current with improved efficiency, reduction in the size of filter components, improved transient response make multi-phase topologies a preferred choice for low voltage-high current applications. Current sensing capability inside a system is much sought after for applications which include Peak-current mode control, Current limiting, Overload protection. Current sensing is extremely important for current sharing in Multi-phase topologies. Existing approaches such as Series resistor, SenseFET, inductor DCR based current sensing are simple but their drawbacks such low efficiency, low accuracy, limited bandwidth demand a novel current sensing scheme. This research presents a systematic design procedure of a 5V - 1.8V, 8A 4-Phase Buck regulator with a novel current sensing scheme based on replication of the inductor current. The proposed solution consists of detailed system modeling in PLECS which includes modification of the peak current mode model to accommodate the new current sensing element, derivation of power-stage and Plant transfer functions, Controller design. The proposed model has been verified through PLECS simulations and compared with a transistor-level implementation of the system. The time-domain parameters such as overshoot and settling-time simulated through transistor-level implementation is in close agreement with the results obtained from the PLECS model.Dissertation/ThesisMasters Thesis Electrical Engineering 201

Observations of aerosol particles and deep convective updrafts and the modeling of their interactions

2020 Spring.Includes bibliographical references.Within cloud updrafts, cloud droplets form on aerosol particles that serve as cloud condensation nuclei (CCN). Varying the concentrations of CCN alters the concentrations of cloud droplets, which in turn modifies subsequent microphysical processes within clouds. In this dissertation, both observational and modeling studies are presented that reduce the uncertainties associated with these aerosol-induced feedback processes in deep convective clouds. In the first study, five years of observations of aerosol particle size distributions from central Oklahoma are compared, and useful metrics are provided for implementing aerosol size distributions into models. Using these unique, long-term observations, power spectra analyses are also completed to determine the most relevant cycles (from hours to weeks) for different aerosol particle sizes. Diurnal cycles produce the strongest signals in every season, most consistently in the accumulation mode and the smallest (diameters < 30 nm) particles. The latter result suggests that these smallest particles may play a more important role in the CCN budget than previously thought. Ultimately, in understanding which, when and why different aerosol particles are present in the atmosphere, we can better assess the impacts that they have on clouds. The types and number of aerosol particles that can serve as CCN depend on the amount of supersaturation, and thus the magnitude of the cloud updraft vertical velocities. However, in situ updraft observations in deep convective clouds are scarce, and other vertical velocity estimates often have uncertainties that are difficult to characterize. In the next study, novel, in situ observations of deep convective updraft vertical velocities from targeted radiosonde launches during the CSU Convective Cloud Outflows and Updrafts Experiment (C3LOUD-Ex) are presented. Vertical velocities of over 50 m s-1 are estimated from radiosonde observations taken in Colorado. Radar data are used to contextualize the radiosonde measurements and to provide an independent estimate of the updraft magnitudes for comparison. These observations are valuable in that they: 1) contribute novel estimates of the vertical velocities within deep convective clouds, 2) demonstrate that in situ observations of vertical velocities complement estimates from other platforms and 3) will allow for better assessments of the supersaturation magnitudes, and thus the amount of CCN that are present within deep convective clouds. While the first two studies focus on observing aerosol particles and updrafts separately, the third study within this dissertation presents simulations of their interactions from an international model intercomparison project. Seven models from different institutions simulated the same case study of isolated deep convective clouds with both high and low CCN concentrations. The range of the responses in updrafts to varying CCN concentrations are calculated for this model suite. Despite the various physical parameterizations that these models utilize, all the models simulate stronger updrafts in the High-CCN simulations from near cloud base through ~8 km AGL, with diverging results above this altitude. The vertical velocity tendency equation is analyzed to explain which processes are causing the consistent and inconsistent updraft responses to varying CCN concentrations amongst the models. The three studies in this dissertation each reduce the uncertainties related to aerosol effects on deep convective cloud updrafts. This work also assisted in motivating the DOE Tracking Aerosol Convection Interactions Experiment (TRACER), which will further connect observational and modeling research to reduce the uncertainties in aerosol-cloud interactions

Continuous Time Least Square PI Control Method for Quasi-Z Source Inverter

This paper presents the proposed model of proportional Integral (PI) controller using continuous time least square method (CT-LSM) for a quasi-Z source inverter (qZSI). PI control is one of the most applicable control methods in power systems. Then, CT-LSM is mainly a statistical optimization method including parameter estimation for nonlinear systems to control. The proposed model is designed to set a control structure without using the nonlinear loads of qZSI and also improve PI control applications against the nonlinear system dynamics. Controller design for qZSI is divided into two parts which are explained as dc side and ac side in both two mode operations. For the dc side of the system, PI controller is designed according to approved system and its estimated parameters which are calculated from state space analysis of qZSI. As for the ac side, the voltage and current regulations are controlled in order to transfer the power to inverter legs based on design criteria. Simulation results by using the current qZSI model on Matlab/Simulink are used to research and analyze the effectiveness and efficiency of the proposed control design