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فهرست مقالات
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دسترسی آزاد مقاله
1 - Evaluation of SMC Synchronous Motor Using Soft Magnetic Compounds and Direct Fuzzy Torque Control
Hossein RefahiAbout 60% of industrial electrical energy is consumed by electric motors. Hence. Extensive efforts have been adopted in order to increase the efficiency of these motors under different operating conditions. Among these motors, the use of three-phase synchronous motors, چکیده کاملAbout 60% of industrial electrical energy is consumed by electric motors. Hence. Extensive efforts have been adopted in order to increase the efficiency of these motors under different operating conditions. Among these motors, the use of three-phase synchronous motors, made of Soft Magnetic Composites (SMC) type, has been growing up in the world during the past decade. The optimal efficiency of these motors is highly sensitive to their mathematical model parameters. In this article, first, the performance of SMC motors is evaluated in detail and the corresponding pros and cons are highlighted in different fields. Then, a mathematical model based on exhaustive simulation, is presented for an SMC motor using Fuzzy Inference Systems (FIS). Given that torque and speed as the outputs, nonlinear methods based on FIS are used. To do so, we assume that only one input at a time can go through the FIS model to account for the input/output relationships. Last but not the least, the parametric model of the motor is cross-evaluated using exhaustive simulation in MATLAB/Simulink. پرونده مقاله -
دسترسی آزاد مقاله
2 - Heat Transfer Analysis and Estimation of CHF in Vertical Channel
K. Dolati Asl E. ‎ Abedini‎ Y. Bakhshan‎ A. Mohammadi Karachi‎ R. Hamidi JahromiHeat transfer occurs in flow boiling; as a result, the amount of heat between the tube wall surface and the fluid at different points of the tube may vary depending on the volume percent of vapor at those points. If the flow is fully vaporized, it does not allow for per چکیده کاملHeat transfer occurs in flow boiling; as a result, the amount of heat between the tube wall surface and the fluid at different points of the tube may vary depending on the volume percent of vapor at those points. If the flow is fully vaporized, it does not allow for perfect heat transfer at that point; this significantly increases the temperature there; in this case the applied heat flux is called critical heat flux (CHF). The present paper has focused its attentions on simulating atwo-phase fluid flow within the CHF range using ANSYS Fluent. The simulation results indicated an average error below 7%, which is more than those obtained by the experimental results. The maximum temperature of the tube surface when applying CHF could range between 200 and 500 K degrees more than that of fluid saturation according to the fluid working conditions. It also should be noted that both CHF and maximum temperature increase as the input pressure and mass flux do increase. پرونده مقاله -
دسترسی آزاد مقاله
3 - Improved Structure Design of a Single Phase Multilevel Inverter with the Aim of Reducing Switching Devices
A. Seifi M. Hoseinpour M. DejamKhoy F. SedaghatiIn this paper, a multilevel inverter has been designed and improved in order to lower the number of switching devices, especially when the number of level of the output power is large. The input to the inverter comes from internal direct current (DC) resources which are چکیده کاملIn this paper, a multilevel inverter has been designed and improved in order to lower the number of switching devices, especially when the number of level of the output power is large. The input to the inverter comes from internal direct current (DC) resources which are interconnected via the power circuit breaker. Compared to the classical topologies and similar designs, the proposed method needs lower number of switching device to provide the same power levels at the output. As a precursor, we have drawn the desired topology for a 9-level power level. The procedure can be completed using switching by a phase shift keying techniques, which in addition, make practical output power with higher number of levels. The proposed topology has been tested against topologies of the power class 1 and/or similar classes, based on the simulations in the MATLAB/Simulink environment. The results of the simulation deemed to be promising for future networks. پرونده مقاله -
دسترسی آزاد مقاله
4 - A Review of Outliers: Towards a Novel Fuzzy Method for Outlier Detection
Arash Mazidi Fahimeh Roshanfar Vahid Parvin DarabadOutliers and outlier detection are among the most important concepts of data processing in different applications. While there are many methods for outlier detection, each detection problem needs to be solved with the method most suited to its unique characteristics and چکیده کاملOutliers and outlier detection are among the most important concepts of data processing in different applications. While there are many methods for outlier detection, each detection problem needs to be solved with the method most suited to its unique characteristics and features. This paper first classifies different outlier detection methods used in different fields and applications to provide a better understanding, and then presents a new fuzzy method for outlier detection. The proposed method uses the fuzzy logic and the local density to assign a point to data instances, and then determines whether a piece of data is normal or outlier based on the value of resulted membership function. Evaluation of the proposed outlier detection algorithm with synthetic datasets demonstrates its good accuracy; moreover, evaluation of the performance in solving real datasets show that the proposed method outperforms the k-means and K-NN algorithms. پرونده مقاله -
دسترسی آزاد مقاله
5 - Peak Electric Load and Related Damages Reduction with the Use of Cooling Ceramics
A. SharifYazdi‎ J. Mirjalili‎ S. SalehiPower outages values are estimated to be between 100 to 150 costly more than the value of electrical energy and; the lack of electricity for industrial, commercial and even household customers has various political, security as well as social consequences. The shortage چکیده کاملPower outages values are estimated to be between 100 to 150 costly more than the value of electrical energy and; the lack of electricity for industrial, commercial and even household customers has various political, security as well as social consequences. The shortage of hydroelectric power and the financial resources to build new power plants caused the summer black-out of the year 1397. The Department of Energy's set of conditions and warnings about the likelihood of escalation in the summer of 98 have drawn serious attention to the consumption pattern correction approach to reduce peak load. Since about 40% of peak load is used for cool buildings, any modification of the cooling pattern will play a decisive role in reducing the peak load. This paper presents a personal contact cooling method (PCCM) using cool, very low cost, one-hundredths of the cost of the practical capacity of the power plant in Peak- bar, without the need for electricity and with very low water consumption. This approach is simple and can be expressed as follows. First humidifies the bricks. These produces fresh and cool air which can by touch /feel externally, be transferred to the cooling of the blood flow and cooling the body internally, and given the evolving experiences, it can provide a significant portion of the cooling need. The use of cool ceramic can reduce production capacity by 1-4 GW by maintaining thermal comfort. In the absence of electricity, this amount of reductions reduces about160 billion riyals of blackout per gigawatt. In the paper's proposed option for the release of one GW (1000 MW) of plant's operational capacity at Peak-bar, the value of the released capacity is approximately 100,000 billion rails. It is also possible to provide people with a part of the cooling power during a power outage. پرونده مقاله -
دسترسی آزاد مقاله
6 - Fault Diagnosis Operator in Linear Fractional Order Singular Systems Using Singular Observer and Unknown Input
F. PourDadashi Komachali M. ShafieeThe singular systems appear in many real occasions of system modeling. Fault occurrence is inevitable in real system; thus to avoid their destructive impacts, new design perspective must be taken. Performance and sensitivity of the fault diagnosis model based methods, h چکیده کاملThe singular systems appear in many real occasions of system modeling. Fault occurrence is inevitable in real system; thus to avoid their destructive impacts, new design perspective must be taken. Performance and sensitivity of the fault diagnosis model based methods, however, significantly dependent on the accuracy of the model. In the one hand, it has been shown that many systems naturally follows the fractional order behavior, while on the other, in some scenarios, fractional modeling has improved the accuracy of the model. In this paper, we pay attention to the fault diagnosis in the fractional order singular systems. To this end, a singular observer with an unknown input has been used for diagnosis of the fault in the fractional order singular system, and the proposed observer convergence will be derived in the form of a linear matrix inequality. An advantage of the proposed method is separation of noise from the desired signal, both in inputs and outputs, using only the inputs and outputs signals. پرونده مقاله -
دسترسی آزاد مقاله
7 - Optimal Sizing and Location of Distributed Generation Units to Improve Voltage Stability and Reduce Power Loss in the Distribution System
M. Kazeminejad M. Ghaffarianfar A. HajizadehVoltage stability improvement, when overloading of current distribution network is leading it toward voltage collapse, has been deemed as an important criteria in networks including distributed generation units (DGs) as part of it. In this condition, DGs can be leverage چکیده کاملVoltage stability improvement, when overloading of current distribution network is leading it toward voltage collapse, has been deemed as an important criteria in networks including distributed generation units (DGs) as part of it. In this condition, DGs can be leveraged to improve reactive power through voltage control and thus, stabilizing network with respect to the voltage. In this paper, a forward-backward power flow with respect to a voltage stability index (VSI), optimal size and location of DGs within the network are to found. The proposed method are simulated on the 34-bus IEEE standard in order to cross validate the results. پرونده مقاله -
دسترسی آزاد مقاله
8 - A New Method for the Residues Cost Allocation and Optimization of a Cogeneration System Using Evolutionary Programming
S.M. SeyyediAs any energy system produces functional products, such as work, heat, etc., it produces unintended remaining flows of matter or energy, too, which are called residues. One of the objectives of exergoeconomic analysis is to understand the cost formation process and the چکیده کاملAs any energy system produces functional products, such as work, heat, etc., it produces unintended remaining flows of matter or energy, too, which are called residues. One of the objectives of exergoeconomic analysis is to understand the cost formation process and the flow of costs in the system. In the conventional thermoeconomic methods, however, the problem of the cost of residues has not been perceived soundly. One of the complex problems in the cost assessment is residues cost allocation in a rational way. Two more important methods of the residues cost allocation are distribution of the cost of the residues proportionally to the exergy as well as to the entropy generation or negentropy. In this paper, a new method for the residues cost allocation is proposed. This new method uses the fuel-product (FP) table, a mathematical representation of the thermoeconomic model, as the input data. In order to represent the proposed method, a cogeneration system that produces 34MW of electricity and 18kg/s of saturated steam at 20bar is selected. For the optimization of this system, first, a code has been developed based on the real coding evolutionary algorithm and optimal solution is to be obtained; then, he proposed method is applied to the cogeneration system. For comparison of the results, two other methods have also been applied to the system. The results of the comparison show that the proposed method is more suitable and rational than the two other ones. پرونده مقاله
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