Дисертації з теми "4008 Electrical engineering"

Oregon utilities are replacing their portfolios of traditional fossil fuel generation with renewable generating sources. Stepping away from carbon-producing energy will leave a deficit of on-demand power, resulting in decreased reliability. To overcome these technical challenges, utilities must maximize the use of their present dispatchable resources. One such resource is the Portland General Electric (PGE) Dispatchable Standby Generation Program (DSG), which is an aggregated 105 MWs of distributed generation (DG). These resources are brought on-line when there is a critical need for power. Resources are added to the program if a transfer trip scheme is in place or a modeling study reveals that the feeder load is at least three times the generator capacity. If the load-to-capacity ratio were lower, more assets could be added to the DSG program. To investigate the impacts of lowering the DG load-to-capacity ratio on existing distribution feeders, we use Open-Source Distribution System Simulator (OpenDSS). We modeled the Oxford Rural feeder by converting a utility CYME database to instantiation files using several MATLAB programs. A MATLAB control program varies the load-to-capacity ratio of the OpenDSS feeder model and monitors the generator behavior immediately following a fault. We analyzed the results to determine the ideal load-to-capacity ratio that prevents unintentional islanding. The results show that the instantaneous (50) relay element settings dictate both the minimum load-to-capacity ratio and the maximum DG capacity. The present three-to-one ratio is very conservative and can be reduced. Additional dispatchable resources include a five MW battery-inverter system currently used as grid-back up. The battery is grid-tied to a 12.4 kV feeder making it an ideal candidate for conservation voltage reduction (CVR). Using the same feeder model, we investigated the effects of lowering the system voltage to the allowable minimum using injections of reactive power. A lower system voltage reduces the load at peak times. Conversely, increasing the voltage prevents generation conflicts. To determine the benefit of CVR by VAr-injection on the Oxford Rural feeder, we created a MATLAB optimization program to output the optimal feeder voltage for reduced system power. We use a Simulink feedback model to determine the appropriate reactive power needed to achieve the voltage change. We analyze the system model to reveal that the feeder is ideal for CVR but the system capacity must be increased to achieve the maximum power reduction.

Includes bibliographical references (leaves 113-115).
This dissertation covers the commissioning and testing of an aircraft's constant frequency alternator as the power supply for the Blue Parrot radar. The Blue Parrot is an X-band radar which forms part of the navigation and weapon-aiming system onboard the Buccaneer S-50 SAAF aircraft. The radar set uses a source of three-phase power at 400 Hz, which the constant frequency alternator can supply with the aid of certain auxiliary systems. The auxiliary systems include a prime mover, blower fan and a telemetering system. The prime mover has high starting currents which were reduced significantly by the use of a soft-starter. During testing, the constant frequency alternator started overheating and a blower fan was selected based on its thermal requirements. Significant cooling of the constant frequency alternator's case temperature was achieved by the use of a blower fan and shroud. The generator control unit monitors and regulates all parameters on the unit except for case temperature and blower fan pressure. A telemetering system was designed and built to monitor and display these parameters.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (p. 177-180).
by Sean Sang-Chul Pak.
M.Eng.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (p. 121-123).
The strength of the high-end retail industry has traditionally been in marketing and branding while management and operational efficiency lagged behind. In the face of changing client demographics and increased competition, improving operations through better data management and utilization could prove promising. In this work, we attempt to do so by focusing on a neglected area in high-end retail - management of the sales associates. Our first finding is the existence of a disconnect between the data collected and the data required for better control of the associates. Recognizing the gap, we sidestep it by tapping the knowledge of many experienced sales associates through field work. This knowledge is then funneled back to assist in modeling client behavior. The dynamics between an associate and his clients are modeled using an evolution model with stochastic client behavior. We show that under certain conditions, the optimal policy for an associate is a quasi-concave policy. In addition, we provide a methodology that would enable the associates to capture the full potential of a client while at the same time, allow management to reduce the variability in customer service within the store. The computational results indicate that such a mechanism, when compared to the commonly practiced policies, can achieve a substantial lift in revenue generated. In addition, the results also provide managerial insights and expose some common misconceptions.
by Shiou Lin Sam.
Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
"February 2006."
Includes bibliographical references (p. 134-135) and index.
This thesis investigates the distributed information and detection of a binary source through a parallel system of relays. Each relay observes the source output through a noisy channel, and the channel outputs are independent conditional on the source input. The relays forward limited information through a noiseless link to the final destination which makes an optimal decision. The essence of the problem lies in the loss of information at the relays. To solve this problem, the characteristics of the error curve are established and developed as a tool to build a fundamental framework for analysis. For understanding, the simplest non-trivial case of two relays, each forwarding only a single binary digit to the final destination is first studied. If the binary output constraint is removed and the output alphabet size for one relay is M, then no more than M + 1 alphabet symbols are required from the other relay for optimal operation. For arbitrary channels, a number of insights are developed about the structure of the optimal strategies for the relay and final destination. These lead to a characterization of the optimal solution. Furthermore, the complete solution to the Additive Gaussian Noise channel is also provided.
by Shan-Yuan Ho.
Ph.D.

The Ku-band SeaWinds-on-QuikSCAT scatterometer (QuikSCAT) operated continuously from 1999 to 2009. Though its primary mission was to estimate global ocean winds, QuikSCAT has proven useful in a variety of geophysical studies using land backscatter measurements. The end of the primary QuikSCAT mission in 2009 has prompted interest for continuing the QuikSCAT land dataset with other scatterometers. The Oceansat-2 scatterometer (OSCAT), launched in 2009, is a viable candidate for continuing the QuikSCAT time series because of the similarities of both sensors in function and design. An important difference in the sensors is that they operate at slightly different incidence angles. Continuing the time series requires careful cross-calibration of the two sensors. Because the sensor datasets overlapped by only a few weeks in late 2009, the amount of simultaneous data is insufficient to describe temporal and locational variations in the relative calibration, or difference between QuikSCAT and OSCAT measurements. To overcome this limitation, we perform direct and model-based comparisons of temporally-disjoint QuikSCAT and OSCAT global land measurements to describe the relative calibration. Using homogeneous rainforest targets, we also identify drift and azimuthal biases in the OSCAT dataset and present suggestions for removing them. The relative calibration is found to vary locationally by several tenths of a decibel over certain regions. Evidence is presented that suggests the relative calibration is dependent on environmental factors such as vegetation density and freeze-thaw status and results from the different incidence angles of the measurements.

Automated vehicles promise to be one of the most constructive inventions of late as they promote road safety, fuel efficiency, and reduced time road travel, by decreasing traffic congestion and workload on the driver. In a platoon (which is a method of grouping vehicles, which helps increase the capacity of roads by managing the distance between vehicles by using electrical and mechanical coupling) of such automated vehicles, as in automated highway systems (AHS), tracking of inter-vehicular spacing is one of the significant factors to be considered. Because of the close spacing, computer-controlled platoons with inter-vehicular communication, which is the concept of adaptive cruise control (ACC), become open to cyber security attacks. Cyber physical and cyber attacks on smart grid systems in the electricity market have been a focus of researchers, and much work has been done on that front. However, cyber physical (CP) attacks on autonomous vehicle platoons have not been examined. Thus this research entails the survey of a number of vehicle models used in different works pertaining to longitudinal vehicle motion and analysis of a special class of cyber physical attacks called false data injection (FDI) attacks on vehicle platoons moving with longitudinal motion. In this kind of attack, an attacker can exploit the configuration of any cyber physical system to launch such attacks to successfully introduce arbitrary errors into certain state variables so as to gain control over the system. So here, an n-vehicle platoon is considered and a linearized vehicle model is used as a testbed to study vehicle dynamics and control, after false information is fed into the system.

An important part in developing the power gridis maintaining the older parts of the system. This reportexamines the reliability of disconnectors ASEA NUB/NUB-Bin the electrical power grid in order for maintenance to beoptimised. Different mathematical models were used to analyseerror statistics of the disconnectors. This is used to obtain animage of the disconnectors life cycle. The report concludes thatASEA NUB 420/2000 have a life expectancy of 20 years and NUBB245/4000 are expected to last for 30 years. It also concludes thatthe amount of data used in this project is insufficient and does notgive a correct representation of the lifespan of the disconnectors.

This thesis presents a novel power side-channel DAC (PS-DAC) which is constructed from user-controllable short circuits in FPGAs and which manipulate overall system power through dynamic power dissipation. Alternately, similar PS-DACs are created using shift-register primitives(SRL16E) which manipulate system power through switching logic, for means of comparison with short-circuit-based PS-DACs. PS-DACs are created of various sizes using both short-circuit-based and shift-register-based methods. These PS-DACs are characterized in terms of output linearity,monotonicity, and frequency distortion. Applications explored in this thesis which use PS-DAC technology include a Simple Power Analysis (SPA) side-channel transmitter, and a frequency watermarking application. These applications serve as proof-of-concept for PS-DAC use in sidechannel communication applications.

A simple and accurate multisheet Brewster angle measurement technique has been developed to measure substrate indices. Both K$ sp+$ and Ag$ sp+$ ion-exchanged optical waveguides in glass substrates were characterized for infrared wavelengths $ lambda=1.152$ and 1.523$ mu m.$ For the characterization of Ag$ sp+$ ion-exchange waveguide, the WKB method has been modified to handle the index truncation point at the waveguide boundary inside the substrate accurately. An explicit and stable finite-difference vector beam propagation method has also been developed for efficient numerical simulations of the guided-wave optical devices.
A modified Y-branch wavelength multi/demultiplexer (abbreviated as WDM) for $ lambda=1.31$ and 1.55 $ mu m$ was designed and optimized by the beam propagation method (abbreviated as BPM). The device, made by K$ sp+$ ion-exchange in glass with a sputtered Al$ rm sb2O sb3$ strip on one branch, can provide high extinction ratios and wide bandwidth. It was successfully fabricated. The measured results of over 20db extinction ratio agree well with the BPM design simulations. A new Y-branch WDM made by K$ sp+$ and Ag$ sp+$ ion-exchanges was proposed and fabricated. It eliminates a difficult fabrication process, involving an Al$ rm sb2O sb3$ strip waveguide, and still provides the other merits of the first device. Its feasibility has been experimentally established. To simplify the fabrication process further, an asymmetric Mach-Zehnder WDM by one step ion-exchange for both two-wavelength and three-wavelength ($ lambda=0.98 mu$m being the third wavelength) was proposed. The BPM simulations show some improvements in several aspects over other types of demultiplexers.

This research has been conducted in order to create a robust, lightweight feature detecting and matching algorithm that builds upon the foundation set by the TreeBASIS algorithm. The goal is to create a color-based version of the TreeBASIS algorithm that uses less hardware resources than the original, is more accurate in its matching capabilities, can successfully be deployed on a resource-limited FPGA platform, and can process in real time. This thesis first presents the newly designed hardware tri-channel FAST Feature Detector that finds features in color. Next the TreeBASIS algorithm is analyzed to discover what improvements can be made in order to reduce its resource usage sufficiently to be able to run on the Xilinx Virtex-4 FX60 while processing color features. At the same time, a software version of the Color TreeBASIS algorithm is compared to the original algorithm and is found to have a 93.3% accuracy on a test set of aerial images, surpassing the accuracy of TreeBASIS by nearly 12%. Then the hardware is meticulously reviewed to discover even more optimizations that allow the Color TreeBASIS algorithm to easily fit onto the Virtex-4 FX60. Next a new application for the matching algorithm, object detection, is introduced as well as the hardware needed to support it. Finally the algorithm is tested on the FPGA system for object detection and is able to successfully identify objects at 60 FPS. Color TreeBASIS proves itself to be more accurate than the TreeBASIS algorithm in the aerial images tests, it ends up using less memory and logic resources than its predecessor, even though it processes three times as much data, it is successfully deployed on a resource-limited FPGA system, and it shows accurate results in real-time object identification, generating an accurate homography 20 to 45% of the time while processing matches at a rate of 60 FPS.

Permanent magnet synchronous motors are finding ever increasing use in hybrid and electric vehicles. This thesis develops a new control strategy for Permanent Magnet Synchronous Motors (PMSMs) to reduce the motor and inverter losses compared to conventional control techniques. The strategy utilises three common control modes for PMSMs; brushless DC with 120°E conduction, brushless DC with 180°E conduction, and brushless AC control. The torque and power output for each control mode is determined for an example motor system using a three phase axial flux YASA motor and an IGBT inverter. The loss components for the motor and inverter are also estimated using a combination of analytical and simulation techniques and results are then validated against experimental measurements. Efficiency maps for each control mode have been used to determine an optimal mode utilisation strategy, which minimises the total system losses and maximises the available motor torque output. The proposed control strategy switches between the three control modes without interruption of motor torque to maximise the system efficiency for the instantaneous operating speed and demanded torque output. The benefits of the new strategy are demonstrated using an example vehicle over a simulated drive cycle. This yields a 10% reduction in losses compared to conventional brushless AC control.

Bibliography: pages 233-235.
The CCITT X.400 Message Handling System resides in the Application Layer of the seven-layer Reference Model for Open Systems Interconnection. It bypasses the services of the Presentation Layer completely to interact directly with the Session Layer. The objectives of this thesis are to show how the general Session Layer may be tailored to be minimally conformant to the requirements of X. 400; to produce a formal specification of this session layer; and to show how this session layer may be implemented on a real system. The session services required by X. 400 are those of the Halfduplex, Minor Synchronization, Exceptions and Activity Management functional units of the CCITT X.215 Session Service Definition. These services, and particularly their use by X.400, are described in detail. State tables describing these services are derived from the general session service state tables. Those elements of the CCITT X. 225 Session Protocol Specification which are required to provide only those services required by X. 400 are described in detail. State tables describing this session protocol are derived from the general session protocol state tables. A formal specification of the session layer for X.400 is presented using the Formal Description Technique Estelle. This specification includes a complete session entity, which characterizes the entire session layer for X.400. A session entity for supporting X.400 is partially implemented and interfaced to an existing X.400 product on a real system. Only the Session Connection Establishment Phase of the session protocol is implemented to illustrate the technique whereby the entire session protocol may be implemented. This implementation uses the C programming language in the UNIX operating system environment.

När flygfarkoster befinner sig på marken får de sin strömförsörjning tillgodosedd genom att vara anslutna mot en GPU (Ground Power Unit), vilket förser flygfarkosten med spänningen 115 V till en frekvens av 400 Hz. Dagens moderna flygfarkoster består av mer avancerad elektronik, vilket kan ge upphov till störningar på den matande GPU som tidigare inte förekommit. Syftet med denna rapport är att undersöka vilka lastfall som kan genereras av en flygfarkost, för att genom en konstruktion kunna återskapa dessa i form av en variabel last. Med hjälp av lasten ska GPU:ers förmåga att upprätthålla spänning och frekvens utvärderas, för att kontrollera om dessa vidhålls trots störningar i form av växlande belastningar. Huvudmålen för rapporten är att fastställa vilka lastfall som kan genereras och återskapa dessa genom en variabel last samt slutligen verifiera och kontrollera framtagen produkt tillsammans med en GPU. En viktig avgränsning för rapporten är att den last som konstrueras inte kommer att kunna genera övertoner, någon som vanligen förekommer bland dagens flygfarkoster. Lasten kommer därigenom enbart att kunna växla mellan att vara induktiv eller kapacitiv. Resultatet från denna rapport visar på att genom konstruktion av en last med lastfallen cos-φ 0,5 0,6 0,7 0,8 0,9 samt -0,5 -0,6 -0,7 -0,8 -0,9, går det att simulera en flygfarkost i form av induktiva och kapacitiva växlingar. Det observeras också genom mätningar att den last som konstruerats ger störningar på spänning och ström liknade det som setts vid mätningar på en verklig flygfarkost.  Slutsatsen för denna rapport är att det går att konstruera en variabel last som kan generera lastfall likt en modern flygfarkost, både teoretiskt och praktiskt. Det går också genom denna last att efterlikna verkliga störningar uppmätta på en GPU, för att därigenom kunna utvärdera dess förmåga att hantera komplexa lastfall.
When an aircraft is on the ground, it receives its power by being connected to a GPU (Ground Power Unit), which supplies the aircraft with a voltage of 115 V to a frequency of 400 Hz. Today's modern aircraft consists of more advanced electronics, which can cause interference to the GPU that not previously existed. The purpose of this report is to investigate which load cases can be generated by an aircraft, to be able to reproduce these in the form of a variable last.  Using the load, the GPU's ability to maintain voltage and frequency should be evaluated to check if these are maintained despite interference in the form of alternating loads. The objectives of this report are to determine which load cases can be generated and recreate these through the variable load, to verify and control the developed product together with a GPU. An important delimitation of the report is that the constructed load will not be able to generate harmonics, which is commonly found among today's aircraft. The load will therefore only be able to switch between being inductive or capacitive. The result of this report shows that by constructing a load with the load case cos-φ 0.5 0.6 0.7 0.8 0.9 and -0.5 -0.6 -0.7 -0, 8 -0.9, it is possible to simulate an aircraft in the form of inductive and capacitive alternations. It has also been seen by measurements that the constructed load causes disturbances in voltage and current similar to those seen in measurements on a real aircraft. This report concludes that it is possible to construct a variable load that can generate load cases similar to a modern aircraft, both theoretically and practically. It also possible to mimic real interference measured on a GPU, thereby evaluate its ability to handle complex load cases.

Cross-linked Polyethylene (XLPE) underground cables are widely used in Victorian power distribution networks due to its lower Dielectric Dissipation Factor (DDF) over Ethylene Propylene Rubber (EPR) cable. Advancement in compounding technology led to the reduction of DDF in some EPR proprietary material. This research investigated the viability of silane-cured low-DDF Tree-Retardant EPR (TR-EPR) cable as an alternative over standard XLPE cable in Victoria. The thermal ageing behaviour of TR-EPR was studied by means of laboratory-based experimentation using accelerated ageing test to observe the time variation of its mechanical properties: tensile strength and elongation at break. Measurements of Partial Discharge (PD) were also conducted prior and after cable heating at service temperature. The results of the thermal ageing test and PD measurements were visually presented through graphs and plots. For the thermal ageing, a theoretical life model was used with the parameters determined using Least Square Regression Method (LSRM). Data from the TR- EPR thermal ageing test were mathematically extrapolated to service temperature through the Arrhenius law to determine the extent of validity of the results. The economic viability of the TR- EPR was also analysed. The results obtained can be utilised by network operators and large industrial companies when designing their underground cable system and taking into consideration the reliability and economy of the power system.

We propose an information theoretic framework for scheduling the transmissions in a two-way multi-hop network. First we investigate some long standing open problems that were encountered during the course of the research. To illustrate their difficulty, we describe some failed attempts at resolving them. We then introduce the two-way one-relay channel. It turns out that the achievable rate region of this network has a nice interpretation, especially when viewed in the context of the open problems examined earlier. Motivated by this observation, we attempt to extend this achievable region to the two-way two-relay channel. In the process, we expose a fundamental deadlock problem in which each relay needs to decode before the other in order to enable mutual assistance. Our most important contribution is a resolution to this deadlock problem; we add an additional constraint that ensures some relay can decode at least one message before the other relay. Furthermore, we also introduce several coding schemes to prove that the additional constraint is indeed sufficient. Our schemes also show that information theory provides unique insight into scheduling the transmissions of multi-hop networks.

Data clustering plays an important role in many disciplines, including data mining, machine learning, bioinformatics, pattern recognition, and other fields, where there is a need to learn the inherent grouping structure of data in an unsupervised manner. There are many clustering approaches proposed in the literature with different quality/complexity tradeoffs. Each clustering algorithm works on its domain space with no optimum solution to all datasets of different properties, sizes, structures, and distributions. Challenges in data clustering include, identifying proper number of clusters, scalability of the clustering approach, robustness to noise, tackling distributed datasets, and handling clusters of different configurations. This thesis addresses some of these challenges through cooperation between multiple clustering approaches. We introduce a Cooperative Clustering (CC) model that involves multiple clustering techniques; the goal of the cooperative model is to increase the homogeneity of objects within clusters through cooperation by developing two data structures, cooperative contingency graph and histogram representation of pair-wise similarities. The two data structures are designed to find the matching sub-clusters between different clusterings and to obtain the final set of cooperative clusters through a merging process. Obtaining the co-occurred objects from the different clusterings enables the cooperative model to group objects based on a multiple agreement between the invoked clustering techniques. In addition, merging this set of sub-clusters using histograms poses a new trend of grouping objects into more homogenous clusters. The cooperative model is consistent, reusable, and scalable in terms of the number of the adopted clustering approaches. In order to deal with noisy data, a novel Cooperative Clustering Outliers Detection (CCOD) algorithm is implemented through the implication of the cooperation methodology for better detection of outliers in data. The new detection approach is designed in four phases, (1) Global non-cooperative Clustering, (2) Cooperative Clustering, (3) Possible outlier’s Detection, and finally (4) Candidate Outliers Detection. The detection of outliers is established in a bottom-up scenario. The thesis also addresses cooperative clustering in distributed Peer-to-Peer (P2P) networks. Mining large and inherently distributed datasets poses many challenges, one of which is the extraction of a global model as a global summary of the clustering solutions generated from all nodes for the purpose of interpreting the clustering quality of the distributed dataset as if it was located at one node. We developed distributed cooperative model and architecture that work on a two-tier super-peer P2P network. The model is called Distributed Cooperative Clustering in Super-peer P2P Networks (DCCP2P). This model aims at producing one clustering solution across the whole network. It specifically addresses scalability of network size, and consequently the distributed clustering complexity, by modeling the distributed clustering problem as two layers of peer neighborhoods and super-peers. Summarization of the global distributed clusters is achieved through a distributed version of the cooperative clustering model. Three clustering algorithms, k-means (KM), Bisecting k-means (BKM) and Partitioning Around Medoids (PAM) are invoked in the cooperative model. Results on various gene expression and text documents datasets with different properties, configurations and different degree of outliers reveal that: (i) the cooperative clustering model achieves significant improvement in the quality of the clustering solutions compared to that of the non-cooperative individual approaches; (ii) the cooperative detection algorithm discovers the nonconforming objects in data with better accuracy than the contemporary approaches, and (iii) the distributed cooperative model attains the same quality or even better as the centralized approach and achieves decent speedup by increasing number of nodes. The distributed model offers high degree of flexibility, scalability, and interpretability of large distributed repositories. Achieving the same results using current methodologies requires polling the data first to one center location, which is sometimes not feasible.

Due to increase in population growth and industrialization process, energy requirements have multiplied. Because of gradual depletion of energy sources resulting from fossil fuels as well as low efficiency and environmental concerns arising from these sources, much attention has been paid to the use of renewable energy sources. The use of resources such as wind and sun that are nominated as clean energy sources has been examined. However, due to the uncertainty of solar radiation and wind speed, their energy production has an unpredictable nature. Therefore, renewable energy resources are used appropriately to form a hybrid system consisting of wind turbines and solar arrays that meets network requirements. A group of power generation systems that are supplied from different sources are known as Hybrid Distributed Generation (HDG). In other words, they work together as complementary group and connect to the distribution network in both the stand-alone and grid-connected ways to supply the load. The presence of DGs in the distribution network has advantages and disadvantages. Voltage support, power loss reduction and reliability improvement are some of the benefits of DGs if their site and size are properly selected in the distribution network. On the other hand, Power Quality (PQ) problem can be defined as any power problem manifested in voltage, current or frequency deviations that fails to meet the requirements of customer equipment. Poor PQ causes tremendous financial losses in deregulated power systems. Today’s electric power systems are connected to many non-linear loads. One PQ problem is harmonic distortion, which is the result of the presence of non-linear loads in the network. Harmonics can cause improper performance in protective equipment, such as relays and fuses. Furthermore, due to the generated heat by the harmonic currents, many consumers and distribution companies are sometimes forced to decrease the amount of output from the transformers. Determination of appropriate location and optimal size of HDG in the distribution network is a main challenge in the changing regulatory and economic scenarios. In this thesis, design and placement of a HDG based on photovoltaic (PV) panel, wind turbines and battery storage (PVWTBAHDG) is proposed to improve the loss reduction and PQ in an unbalanced 33-bus radial distribution network. Further, in this research, improvement of voltage sag, voltage swell, Total Harmonic Distortion (THD) and voltage unbalance are considered as PQ indexes. The HDG system is designed to supply a residential load and it is able to inject its excess power into the distribution network. The PVWTBAHDG system has been designed to minimize the energy generation costs including initial investment costs and maintenance and operation costs. Therefore, the site and size of PVWTBAHDG components are optimally determined considering the total objective function of the system which includes decreasing the losses, reducing the cost of energy generation by the HDG and improving the power quality indexes. In this research, based on the social and intelligent behavior of crows, a hybrid meta-heuristic method named Crow Search Algorithm-Differential Evolution (HCSADE) is proposed to determine the location and size of PVWTBAHDG components in the network. In order to avoid the Crow Search Algorithm (CSA) from trapping in the local optima and increase the convergence speed of the algorithm, the crossover and mutation operators of the Differential Evolution (DE) method are employed to improve the CSA performance. Simulations have been implemented in several scenarios of single and multi-objective optimizations. Multi-objective results are obtained by compromising the results of single- objective optimization. The simulation results show that the HCSADE method presents a desirable performance in optimal sizing and siting the PVWTBAHDG in the network and also causes loss reduction and PQ improvement. The superiority of the HCSADE is confirmed in comparison with CSA and DE methods in terms of better objective function. Moreover, the results prove that increasing the number of PVWTBAHDG causes further reduction in the PQ indices and losses.

This thesis contributes toward understanding fundamental limits of multi-user fading channels and random wireless networks. Specifically, considering different samples of channel gains corresponding to different users/nodes in a multi-user wireless system, the maximum number of channel gains supporting a minimum rate is asymptotically obtained. First, the user capacity of fading multi-user channels with minimum rates is analyzed. Three commonly used fading models, namely, Rayleigh, Rician and Nakagami are considered. For broadcast channels, a power allocation scheme is proposed to maximize the number of active receivers, for each of which, a minimum rate Rmin>0 can be achieved. Under the assumption of independent Rayleigh fading channels for different receivers, as the total number of receivers n goes to infinity, the maximum number of active receivers is shown to be arbitrarily close to ln(P.ln(n))/Rmin with probability approaching one, where P is the total transmit power. The results obtained for Rayleigh fading are extended to the cases of Rician and Nakagami fading models. Under the assumption of independent Rician fading channels for different receivers, as the total number of receivers n goes to infinity, the maximum number of active receivers is shown to be equal to ln(2P.ln(n))/Rmin with probability approaching one. For broadcast channels with Nakagami fading, the maximum number of active receivers is shown to be equal to ln(ω/μ.P.ln(n))/Rmin with probability approaching one, where ω and μ are the Nakagami distribution parameters. A by-product of the results is to also provide a power allocation strategy that maximizes the total throughput subject to the rate constraints. In multiple-access channels, the maximum number of simultaneous active transmitters (i.e. user capacity) is obtained in the many user case in which a minimum rate must be maintained for all active users. The results are presented in the form of scaling laws as the number of transmitters increases. It is shown that for all three fading distributions, the user capacity scales double logarithmically in the number of users and differs only by constants depending on the distributions. We also show that a scheduling policy that maximizes the number of simultaneous active transmitters can be implemented in a distributed fashion. Second, the maximum number of active links supporting a minimum rate is asymptotically obtained in a wireless network with an arbitrary topology. It is assumed that each source-destination pair communicates through a fading channel and destinations receive interference from all other active sources. Two scenarios are considered: 1) Small networks with multi-path fading, 2) Large Random networks with multi-path fading and path loss. In the first case, under the assumption of independent Rayleigh fading channels for different source-destination pairs, it is shown that the optimal number of active links is of the order log(N) with probability approaching one as the total number of nodes, N, tends to infinity. The achievable total throughput also scales logarithmically with the total number of links/nodes in the network. In the second case, a two-dimensional large wireless network is considered and it is assumed that nodes are Poisson distributed with a finite intensity. Under the assumption of independent multi-path fading for different source-destination pairs, it is shown that the optimal number of active links is of the order N with probability approaching one. As a result, the achievable per-node throughput obtained by multi-hop routing scales with Θ(1/√N).