Seyed Mahyar Mehdizadeh Moghadam; Alireza Khosravi; Seyed Mehdi Rakhtala Rostami
Volume 11, Issue 4 , December 2017, Pages 1-9
Abstract
In this article, the dynamic modeling of different electrical and mechanical parts of the nonlinear aerodynamics of variable speed wind turbine (DFIG) has been done. A high order sliding mode robust controller has been used to decrease the chattering effect in the presence of wind stochastic model, uncertainties ...
Read More
In this article, the dynamic modeling of different electrical and mechanical parts of the nonlinear aerodynamics of variable speed wind turbine (DFIG) has been done. A high order sliding mode robust controller has been used to decrease the chattering effect in the presence of wind stochastic model, uncertainties of model dynamic error and mechanical power factor. The nonlinear robust control guarantees the performance and robust stability in order to reduce the effect of sliding instabilities and improve the turbine rotor speed changes for different angles of blade pitch. The simulation results confirmed the convergence of turbine rotor speed output and the improvement of tracking error in the presence of system uncertainties.
Soorena Zohoori; Mehdi Dolatshahi
Volume 11, Issue 4 , December 2017, Pages 11-19
Abstract
In this paper, an optical communication receiver system for 5Gbps applications is proposed concerning power consumption. An inductor-less circuit in three-stages is proposed as the trans-impedance amplifier (TIA), which benefits from the inherent low input resistance of a common gate topology as the ...
Read More
In this paper, an optical communication receiver system for 5Gbps applications is proposed concerning power consumption. An inductor-less circuit in three-stages is proposed as the trans-impedance amplifier (TIA), which benefits from the inherent low input resistance of a common gate topology as the first stage. By forming two zeros in this TIA, proper frequency response is obtained while the DC current is reduced. In order to obtain extra gain for the receiver system, three stages of a conventional limiting amplifier (LA) are used. In order to verify the circuit performance, the proposed receiver is simulated in HSPICE using 90nm CMOS technology parameters. The receiver is mathematically studied and is matched with the simulations. Simulations, such as eye-diagram, noise analysis and fabrication process analysis (Monte-Carlo) are done in this paper. The proposed TIA shows 53.9dbΩ trans-impedance gain, 3.5GHz bandwidth, 15.2pA/√Hz and only 1.52mw power consumption for 1.2v supply voltage, and the receiver system shows 90.9dbΩ, 3.5GHz bandwidth and 6.34mw power consumption (for 2stages of TIA and 3stages of LA) for 1.2v supply voltage. Results indicate that the proposed receiver is suitable to work as a low-power 5Gbps optical communication receiver system.
Hossein Sharifi; Hasan Ghafori; Behrooz Sadeghian
Volume 11, Issue 4 , December 2017, Pages 21-26
Abstract
Engines with variable poppet valve timing systems are among numerous efforts that aim to reduce engine emissions and/or increase efficiency. In the present paper we have investigated the stability of a magnetic valve system in MATLAB. First we designed the magnet and interactive forces inside the electromagnetic ...
Read More
Engines with variable poppet valve timing systems are among numerous efforts that aim to reduce engine emissions and/or increase efficiency. In the present paper we have investigated the stability of a magnetic valve system in MATLAB. First we designed the magnet and interactive forces inside the electromagnetic valve system, then we produced a mechanical model for the system by using a two degree of freedom mass and spring system and finally designed a PID controller to maintain system stability. The results of the present study indicate that the controller had decreased the maximum valve displacement domain and duration from 2 mm to 0.001 mm and 0.1 seconds to 0.022 seconds, respectively. Poppet valve settling speed was 0.0126 and had a standard deviation of 0.1304 while the armature settling speed was 0.0184, with a standard deviation of 0.1363. Passes for the phases were -37.5 and -169, with gains of 10.3 and -9.35.
Saber Falahati Aliabadi; Seyyd Abbas Taher
Volume 11, Issue 4 , December 2017, Pages 27-35
Abstract
In this paper Fuzzy-FOPID controller is used in order to control automatic voltage regulator (AVR) system. This controller has six parameters. In this paper, optimization method is employed to determine the controller parameters. For this purpose, imperialist competitive algorithm (ICA) is used for its ...
Read More
In this paper Fuzzy-FOPID controller is used in order to control automatic voltage regulator (AVR) system. This controller has six parameters. In this paper, optimization method is employed to determine the controller parameters. For this purpose, imperialist competitive algorithm (ICA) is used for its high accuracy and good performance. To illustrate performance of proposed controller, some simulations are carried out in MATALB and the results are compared with FOPID controller results. Good performance of proposed controller is validated by results of the simulations.
Payman Bahrami; Mohammad Reza Shayesteh; Mohammad Eslami
Volume 11, Issue 4 , December 2017, Pages 37-43
Abstract
This paper presents the simulation of the process of LDMOS transistor manufacturing by using Silvaco software and by relying on the ability of calculating the basic parameters of transistor dependencies, focusing on the optimization of the manufacturing process in order to increase the current of work. ...
Read More
This paper presents the simulation of the process of LDMOS transistor manufacturing by using Silvaco software and by relying on the ability of calculating the basic parameters of transistor dependencies, focusing on the optimization of the manufacturing process in order to increase the current of work. The simulation of manufacturing process of this type of transistor which is a base for its real manufacturing is of the utmost importance. By using this simulation and reviewing each parameter, we can achieve the optimized manufacturing process by focusing each basic parameter and by paying attention to its required application. In order to design, we first define the construction procedures and the necessary processes using the Athena simulator, and then we use the Atlas device simulator to acquire electrical parameters.
Mahdi Dibaei; Ali Ghaffari
Volume 11, Issue 4 , December 2017, Pages 45-52
Abstract
Security is considered to be one of the most important challenges in wireless sensor networks (WSNs). Due to inherent resource constraints in WSNs, traditional security mechanisms may not be used in these networks. In recent years, trust and reputation management in distributed systems has been proposed ...
Read More
Security is considered to be one of the most important challenges in wireless sensor networks (WSNs). Due to inherent resource constraints in WSNs, traditional security mechanisms may not be used in these networks. In recent years, trust and reputation management in distributed systems has been proposed as a novel and accurate way for handling security deficiencies. Such deficiencies are deemed to be inherent in WSNs. Detecting malicious nodes is an important role of Trust models in WSNs. In line with reducing the above-mentioned deficiencies, the present paper has proposed a trust-based scheme for increasing security (TSIS) model for WSNs. The proposed trust-based scheme divides the network into some clusters. Inside each cluster, a special node named supervisor node is responsible for calculating the trust values of other nodes. When supervisor nodes calculate trust values of other nodes in a cluster, they do not distribute these values. The receiver node requests the sender node authentication from its own supervisor node. The proposed method was simulated in the NS-2 environment. The simulation results indicate that the proposed method has improved energy efficiency and packet delivery rate. Hence, it has better performance than the earlier works with respect to the above-mentioned parameters.
Bahram Azizollah Ganji; Mehdi Taybi
Volume 11, Issue 4 , December 2017, Pages 53-57
Abstract
In this paper we presented a novel MEMS acoustic sensor using corrugated diaphragm. The corrugated diaphragm is used to decrease the effect of residual stress and thus improve the sensitivity of micromachined acoustic sensor. The displacement and mechanical sensitivity of flat and corrugated diaphragms, ...
Read More
In this paper we presented a novel MEMS acoustic sensor using corrugated diaphragm. The corrugated diaphragm is used to decrease the effect of residual stress and thus improve the sensitivity of micromachined acoustic sensor. The displacement and mechanical sensitivity of flat and corrugated diaphragms, and also open-circuit sensitivity and pull-in voltage of sensors are calculated using MATLAB and simulated using FEM (finite element method). The results show that the displacement and mechanical sensitivity of corrugated diaphragm are bigger than the flat one. The pull-in voltage of corrugated sensor is smaller and the open-circuit sensitivity is much higher than the sensor with flat diaphragm. The results also show that the analytical model is very close with FEM simulation results.
Farkhondeh Jabari; Mohammad Bagher Bannae Sharifian; Behnam Mohammadi-ivatloo
Volume 11, Issue 4 , December 2017, Pages 59-65
Abstract
During the extremely-hot weather or transient heat waves, air conditioners are the main contributors to highest peak electricity demand which may lead to the widespread blackouts or brownouts. Meanwhile, electric drive vehicles are rapidly gaining popularity due to the global warming and energy crisis. ...
Read More
During the extremely-hot weather or transient heat waves, air conditioners are the main contributors to highest peak electricity demand which may lead to the widespread blackouts or brownouts. Meanwhile, electric drive vehicles are rapidly gaining popularity due to the global warming and energy crisis. Hence, this paper schedules on optimal charge and discharge decisions of plug-in electric vehicles (PEV) in a residential cooling and power microgrid that is driven by a solar Stirling engine. In the presented microgrid, the solar dish Stirling heat engine is employed as an external combustion engine to supply the electricity requirement of compressor, evaporator and condenser fans and charge the PEVs in the off-peak cooling-load hours. During the on-peak periods, optimal discharge of PEVs increases total energy and emission savings significantly. A thermodynamic based mixed integer nonlinear programming (MINLP) problem is solved to minimize total electricity cost for a benchmark residential building located in a tropical region taking into account the operational constraints of the Stirling engine and the refrigeration cycle. Simulation results demonstrate that this micro-cogeneration system can be introduced as a near-zero energy building with zero-carbon footprint in the presence of PEVs.
