Original Research Paper
Power
H. Amiri; G. Arab Markadeh; N. Mahdian
Abstract
Background and Objectives: Increasing DC loads along with DC nature of distributed energy resources (DERs) raises interest to DC microgrids. Conventional droop/non-droop power-sharing in microgrids suffers from load dependent voltage deviation, slow transient response, and requires the parameters of ...
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Background and Objectives: Increasing DC loads along with DC nature of distributed energy resources (DERs) raises interest to DC microgrids. Conventional droop/non-droop power-sharing in microgrids suffers from load dependent voltage deviation, slow transient response, and requires the parameters of the loads, system and DERs connection status.Methods: In this paper, a new nonlinear decentralized back-stepping control strategy for voltage control and load sharing of DC islanded microgrids is proposed. The proposed method is robust against the load variations and uncertainty in microgrid parameters and has excellent dynamic and steady-state performance under different operating conditions. The major purpose of the proposed controller is to improve the transient performance of MG with load variations and constant power loads (CPLs). The local controller regulates the terminal voltage of DC-DC converter regarding the local quantities without needs to additional data of other system components.Results: For simplicity, the proposed method is simulated with PSIM software on a DC microgrid with two DGs. Different scenarios are studied to present the performance of the proposed method under different operating conditions.Conclusion: The results indicate the capability of the proposed method for voltage control and load sharing in DC microgrids.
Original Research Paper
Power
H. Lasjerdi; Z. Nasiri-Gheidari; F. Tootoonchian
Abstract
Background and Objectives: Wound-Rotor resolvers are the most widely used position sensors in applications with harsh environmental conditions.Methods the resolver performance is exposed to failure due to the high risk of short circuit (SC) fault. Although the output current of the resolver is negligible, ...
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Background and Objectives: Wound-Rotor resolvers are the most widely used position sensors in applications with harsh environmental conditions.Methods the resolver performance is exposed to failure due to the high risk of short circuit (SC) fault. Although the output current of the resolver is negligible, its thin copper wires increase the probability of the short circuit fault. To avoid the propagation of the turn-to-turn SC fault to the whole coil and undesirable performance of the motion control drive, it is necessary to diagnose it at the very beginning of its development. Meanwhile, the first step of diagnosing faults is their modeling. Time stepping finite element analysis is the most accurate, but computationally expensive method for modeling electromagnetic devices. Therefore, it is required to establish an accurate,Results: In this paper, an analytical model based on d-q axes theory is proposed to consider multiple faults, simultaneously. Then, the success of the proposed model is validated by experimental tests on the studied sensor.Conclusion: the proposed model is fast and accurate, so it can be used for the design process.
Original Research Paper
Electronics
F. Abdi; P. Amiri; M.H. Refan
Abstract
Background and Objectives: Adaptive algorithm adjusts the system coefficients based on the measured data. This paper presents a dichotomous coordinate descent method to reduce the computational complexity and to improve the tracking ability based on the variable forgetting factor.Methods: Vedic mathematics ...
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Background and Objectives: Adaptive algorithm adjusts the system coefficients based on the measured data. This paper presents a dichotomous coordinate descent method to reduce the computational complexity and to improve the tracking ability based on the variable forgetting factor.Methods: Vedic mathematics is used to implement the multiplier and the divider operations in the VFF equations. The linear exponentially weighted recursive least squares as the main algorithm is implemented in many applications such as the adaptive controller, the system identification, active noise cancellation techniques, and etc. The DCD method calculates the inverse matrix in the ERLS algorithm and decreases the resources used in the field-programmable gate array, also the designer can use the cheaper FPGA board to implement the adaptive algorithm because the method doesn't need lots of resources.Results: The proposed method is implemented with ISE software on the Spartan 6 Xilinx board. The proposed algorithm calculates the multiplication result with less than 15ns time and reduces the used FPGA resources to lower than 20% as compared with the classic RLS.Conclusion: The proposed method decreases the area and increases the computation speed. Also, it leads to implementing complex algorithms with simple structures and high technology.
Original Research Paper
Electronics
M. Karbalaei; D. Dideban; N. Moezi
Abstract
Background and Objectives: In this work, a dual workfunction gate-source pocket-retrograde doping-tunnel field effect transistor (DWG SP RD-TFET) is proposed and investigated.Methods: The dual workfunction gate-source pocket-retrograde doping-tunnel field effect transistor is a Silicon-channel TFET with ...
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Background and Objectives: In this work, a dual workfunction gate-source pocket-retrograde doping-tunnel field effect transistor (DWG SP RD-TFET) is proposed and investigated.Methods: The dual workfunction gate-source pocket-retrograde doping-tunnel field effect transistor is a Silicon-channel TFET with two isolated metal gates (main gate and auxiliary gate) and a source pocket in the channel close to the source-channel junction to increase the carrier tunneling rate.Results: For further enhancement in the tunneling rate, source doping near the source-channel junction, i.e., underneath the auxiliary gate is heavily doped to create more band bending in energy band diagram. Retrograde doping in the channel along with auxiliary gate over the source region also improve device subthreshold swing and leakage current. Based on our simulation results, excellent electrical characteristics with ION/IOFF ratio > 109, point subthreshold swing (SS) of 6 mV/dec and high gm/ID ratio at room temperature shows that this tunneling FET can be a promising device for low power applicationsConclusion: In order to increase the ON-current in this device, we utilized several methods including incorporation of high-K material in top oxide, source pocket in channel and a thin auxiliary gate with high workfunction over the source region. Incorporating auxiliary gate over the source also caused a barrier formation in the energy band diagram profile of this device which it leds electron concentration in the channel, subthreshold swing and OFF-current to be reduced.
Original Research Paper
Power
H. Berahmandpour; S. M. Kouhsari; H. Rastegar
Abstract
Background and Objectives: Uncertainty and variability are two main specifications of wind generation and the ability of the power system to overcome these challenges is called flexibility. The flexibility index is a measure to evaluate the flexibility level of the power system mainly to achieve the ...
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Background and Objectives: Uncertainty and variability are two main specifications of wind generation and the ability of the power system to overcome these challenges is called flexibility. The flexibility index is a measure to evaluate the flexibility level of the power system mainly to achieve the best level system flexibility.Methods: Flexibility index should show a good view of the ability of the power system and also be easily converted to an equivalent cost to be combined with the operation cost function. So, in this paper by using economic dispatch simulation for the economic trade-off between the generation cost and the cost of flexibility, the best level of system flexibility in the presence of wind farms considering unit constraints and system loss is achieved. Where the difference between flexibility index in the no wind base case and the flexibility index in each time zone with wind incorporation is defined as the flexibility penalty by the suitable penalty factor. The combination of generation cost and flexibility cost makes the main part of objective function.Results: The results on the test system verify the proposed method where by increasing penalty factor, improvement in flexibility index is achieved but the generation cost will be increased. So, it shows a good economic trade-off between generation cost and flexibility value. Also the desired flexibility level can be obtained by changing the penalty factor in each wind power penetration. So, the result of the sensitivity analysis shows the best level of flexibility regarding operation cost.Conclusion: In this paper a new flexibility index is introduced especially for wind power incorporation and for real time operation purpose. This index can be combined by economic dispatch objective function as the penalty (cost) for economic trade-off analysis and to show the best flexibility level of generation system in each operation point.
Original Research Paper
Power
R. Sedaghati; M. Mahmoudian
Abstract
Background and Objectives: Coriolis vibratory gyroscope is one of the most modern types of gyroscopes that has been substituted for the common gyroscopes with some differences in the test mass design and elastic suspension. According to the important features observed in the capacitive excitation of ...
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Background and Objectives: Coriolis vibratory gyroscope is one of the most modern types of gyroscopes that has been substituted for the common gyroscopes with some differences in the test mass design and elastic suspension. According to the important features observed in the capacitive excitation of the actuators regarding the piezoelectric actuators, the operation principles and their formulations are completely changed, which require both two dimensional and finite element analysis to evaluate their optimal performance. Because the sensors are usually vibrating continuously while operation.Methods: In this paper a general framework is presented that fully describes the influence of the parameters related to different frequency operating modes. The main idea of the vibration gyroscope is to replace the rotational rotor with a vibrational structure to utilize the effects of Coriolis force, which causes the secondary motion of a sensitive mass to match an angular velocity.Results: In this paper, the sensitivity analysis and performance evaluation of a hemispherical vibrational gyroscope are discussed. The frequency split phenomenon, the sensed voltage around the resonance frequency and Young's modulus variation are also investigated.Conclusion: Finally, the results of the simulated resonance frequencies are compared and validated with the mathematical and theoretical principles.
Original Research Paper
Control
M. I. Hosseini; M.R. Jafari Harandi; S. A. Khalilpour Seyedi; H. Taghirad
Abstract
Background and Objectives: Fast-tracking of reference trajectory and performance improvement in the presence of dynamic and kinematic uncertainties is of paramount importance in all robotic applications. This matter is even more important in the case of cable-driven parallel robots due to the flexibility ...
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Background and Objectives: Fast-tracking of reference trajectory and performance improvement in the presence of dynamic and kinematic uncertainties is of paramount importance in all robotic applications. This matter is even more important in the case of cable-driven parallel robots due to the flexibility of the cables. Furthermore, cables are limited in the sense that they can only apply tensile forces, for this reason, feedback control of such robots becomes more challenging than conventional parallel robots.Methods: To address these requirements for a suspended cable-driven parallel robot, in this paper a novel adaptive fast terminal sliding mode controller is proposed and then the stability of the closed-loop system is proven. In the proposed controller, a nonlinear term as a fractional power term is used to guarantee the convergent response at a finite time.Results: At last, to show the effectiveness of the proposed controller in tracking the reference trajectory, simulations and the required experimental implementation is performed on a suspended cable-driven robot. This robot, named ARAS-CAM, has three degrees of transmission freedom.Conclusion: The obtained experimental results confirm the suitable performance of this method for cable robots in the presence of dynamic uncertainties.
Original Research Paper
Artificial Intelligence
F. Jamshidi; M. Vaghefi
Abstract
Background and Objectives: A robot arm is a multi-input multi-output and non-linear system that has many industrial applications. Parameter uncertainties and external disturbances attenuate the performance of this system and a controller design is hence necessary to overcome them.Methods: In ...
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Background and Objectives: A robot arm is a multi-input multi-output and non-linear system that has many industrial applications. Parameter uncertainties and external disturbances attenuate the performance of this system and a controller design is hence necessary to overcome them.Methods: In this paper, the interval Type II Fuzzy fractional-order proportional integral differential (IT2FO-FPID) controller is designed to control a robot arm with 2 degrees of freedom (two-link robot arm). Whale optimization algorithm (WOA) is used to determine the optimal value of controller parameters. The performance of IT2FO-FPID is compared with PID, fractional-order PID (FOPID) and Fuzzy FOPID whose parameters are determined by WOA. The performance of IT2FO-FPID whose parameters are determined by WOA, genetic algorithm, and particle swarm optimization methods are compared.Results: Quantitative and qualitative results of simulations indicate performance improvement with the IT2FO-FPID controller. The ability of WOA in optimizing the parameters of the IT2FO-FPID controller is demonstrated.Conclusion: Sensitivity analysis and the study of the effect of parameter variations and disturbances confirm the robust performance of WOA-based IT2FO-FPID.
Original Research Paper
Control
H. Nasiri Soloklo; N. Bigdeli
Abstract
Background and Objectives: In this paper, a predictive functional control based on Laguerre functions is designed for control of an industrial heating furnace. The fractional order model (FOM) of the heating furnace is assumed as the plant model.Methods: For designing the predictive functional controller ...
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Background and Objectives: In this paper, a predictive functional control based on Laguerre functions is designed for control of an industrial heating furnace. The fractional order model (FOM) of the heating furnace is assumed as the plant model.Methods: For designing the predictive functional controller (PFC), a reduced integer order approximation of the fractional order heating furnace model is derived. The order of the reduced integer model is determined based on Hankel singular values of the original system. Coefficients of the reduced integer model are assumed to be unknown. Unknown parameters are then obtained by minimizing a many-objective fitness function including weighted summation of differences of step responses, steady state errors, maximum overshoots as well as magnitude of frequency responses of the original and reduced systems. Routh-Hurwitz criteria are used as stability criteria and added to optimization problem as its constraints. The optimization tool is Genetic algorithm.Results: Advantages of the proposed method are preserving stability and focusing on various important features of both time and frequency responses of system. In addition, it uses a direct order reduction method without the need to intermediated approximations such as Oustaloup approximation.Conclusion: Laguerre-based PFC controller has been evaluated via two scenarios and the obtained results represent the satisfactory performance of the proposed controller.
Original Research Paper
Computational Intelligence
M.R. Esmaeili; S.H. Zahiri; S.M. Razavi
Abstract
Background and Objectives: High-level synthesis (HLS) is one of the substantial steps in designing VLSI digital circuits. The primary purpose of HLS is to minimize the digital units used in the system to improve their power, delay, and area.Methods: In the modified MFO algorithm presented in this paper, ...
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Background and Objectives: High-level synthesis (HLS) is one of the substantial steps in designing VLSI digital circuits. The primary purpose of HLS is to minimize the digital units used in the system to improve their power, delay, and area.Methods: In the modified MFO algorithm presented in this paper, a hyperbolic spiral is chosen as the update mechanism of moths. Also, by presenting a new approach, a paramount issue involved in applying meta-heuristic methods for solving HLS problems of VLSI circuits has been disentangled.Results: By comparing the performance of the proposed method with Genetic algorithm (GA)-based method and particle swarm optimization (PSO)-based method for the synthesis of the digital filters, it is concluded that the proposed method has the higher ability in the HLS of data path in digital filters. The best improvement is 2.78% for the delay (latency), 6.51% for the occupied area of the chip and 6.93% in power consumption. Another feature of the proposed method is its high-speed in finding optimal solutions, in a manner which, more than 21.6% and 12.9% faster than the GA-based and PSO-based methods, respectively on average.Conclusion: The most important very large scale integration (VLSI) circuits are digital filters and transformers, which are widely used in audio and video processing, medical signal processing, and telecommunication systems. The complex, expansive, and discrete nature of design space in high-level synthesis problems has made them one of the most difficult problems in VLSI circuit design.
Original Research Paper
Software
M.S. Mohagheghi
Abstract
Background and Objectives: Numerical iterative methods are widely used to compute reachability probabilities and expected rewards in probabilistic model checking of Markov decision processes. Several approaches have been proposed to improve the performance of these iterative methods. Reducing the total ...
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Background and Objectives: Numerical iterative methods are widely used to compute reachability probabilities and expected rewards in probabilistic model checking of Markov decision processes. Several approaches have been proposed to improve the performance of these iterative methods. Reducing the total number of iterations is an important goal that is followed by several techniques in this paper.Methods: In this paper, we consider MDPs with different levels of non-determinism. We show that modified policy iteration performs better than the other standard iterative methods when the degree of non-determinism increases. We propose some novel methods to improve the performance of the modified policy iteration method. Our approach is to define several criteria to avoid useless iterations and updates of the modified policy iteration method. The first criterion considers the graphical structure of the model to define the number of iterations after each policy modification. The second criterion is a dynamic one to determine when a policy should be updated. The third proposed approach in this work is to use several priority heaps to select states for value updates.Results: Our proposed methods are implemented in the PRISM model checker and applied on several standard case studies. The results of experiments show that the running times of our approaches are less than the running time of the standard and previous methods for most case studies. The main reason for these results is that the total numbers of iterations and updates are reduced by our approaches, which results in an improvement in the performance of the method. While the running times are reduced by our approaches, the precision of computations are kept in most cases.Conclusion: The proposed techniques are able to reduce the number of iterations and accelerate the convergence to the optimal policies. The also prioritize the commutations to reduce the total number of updates.
Original Research Paper
Modelling, simulation and verification
S.M. Nematollahzadeh; S. Ozgoli; M. Sayad Haghighi
Abstract
Background and Objectives: One of the interesting topics in the field of social networks engineering is opinion change dynamics in a discussion group and how to use real experimental data in order to identify an interaction pattern among individuals. In this paper, we propose a method that utilizes experimental ...
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Background and Objectives: One of the interesting topics in the field of social networks engineering is opinion change dynamics in a discussion group and how to use real experimental data in order to identify an interaction pattern among individuals. In this paper, we propose a method that utilizes experimental data in order to identify the influence network between individuals in social networks.Methods: The employed method is based on convex optimization and can identify interaction patterns precisely. This technique considers individuals’ opinions in multiple dimensions. Moreover, the opinion dynamics models that have been introduced in the literature are investigated. Then, the three models which are the most comprehensive and vastly accepted in the literature, are considered. These three models are then proven to satisfy the convexity condition, which means they can be used for the introduced method of identification.Results: Four real experiments have been conducted in this research that their results verify the application of our method. The outcomes of these experiments are presented in this paper.Conclusion: Results show that the provide method is suited for parameter identification for opinion dynamic models.
