48 results
Search Results
2. Comparative analysis of a novel topology for single-phase Z-source inverter with reduced number of switches.
- Author
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SHARMA, Himanshu, KHANNA, Rintu, and JAIN, Neelu
- Subjects
ELECTRIC inverters ,ELECTRIC switchgear ,COMPARATIVE studies ,COMPUTER simulation ,ELECTRIC potential - Abstract
Z-source inverter has recently been introduced to overcome the limitations of conventional voltage source inverter. This paper deals with a novel topology of single-phase Z-source inverter (ZSI). This topology reduced the number of passive elements and active switches in order to make the inverter cheaper and smaller in size compared to traditional ZSI. Detailed analysis of the proposed topology is presented in this paper which includes calculations of boost factor, total harmonic disorder, magnitude of output voltage etc. Modulation technique used to control the switching of the proposed inverter is explained in detail. This paper also compares the proposed topology with conventional topologies of Z-source inverter. Simulation results of MATLAB and real-time simulators are shown to explain the working of the proposed topology. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
3. Analyzing bifurcation, stability, and chaos control for a discrete-time prey-predator model with Allee effect.
- Author
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KANGALGİL, Figen, TOPSAKAL, Nilüfer, and ÖZTÜRK, Nihal
- Subjects
ALLEE effect ,PREDATION ,BIFURCATION theory ,COMPUTER simulation ,PSYCHOLOGICAL feedback - Abstract
In this paper, the qualitative behavior of a discrete-time prey-predator model with Allee effect in prey population is discussed. Firstly, the existence of the fixed points and their topological classification are analyzed algebraically. Then, the conditions of existence for both period-doubling and Neimark-Sacker bifurcations arising from coexistence fixed point with the help of the center manifold theorem and bifurcation theory are investigated. OGY feedback control method is implemented to control chaos in the proposed model due to the emergence of bifurcations. Finally, numerical simulations are performed to support the theoretical findings. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Neural network controller for nanopositioning of a smooth impact drive mechanism.
- Author
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Xiaohui LU, Dong CHEN, Tinghai CHENG, and Zhe LI
- Subjects
ELECTRIC controllers ,ARTIFICIAL neural networks ,NANOPOSITIONING systems ,COMPUTER simulation ,PID controllers - Abstract
In this paper, neural network theory is used to improve the positioning accuracy of smooth impact drive mechanisms (SIDMs), by designing a displacement controller that consists of a neural network identification (NNI) and a neural network controller (NNC). The dynamics of the SIDM are described by the NNI, which consists of an input layer, hidden layer, and output layer. The parameters of the NNI are adjusted using back propagation. The NNC is designed as a proportional-derivative (PD) controller, which is used to accurately control the displacement of the SIDM. The PD parameters are adjusted with an adaptive adjustment algorithm. A prototype of the SIDM was fabricated and an experimental control system was built that consists of a laser displacement sensor, power amplifier, data acquisition board, and SIDM prototype. The experimental results show that nanoscale positioning accuracy can be obtained. The control system can maintain steady operation, even if the output load mass is changed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
5. A developed flywheel energy storage with built-in rotating supercapacitors.
- Author
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TOODEJI, Hamidreza
- Subjects
FLYWHEELS ,ENERGY storage ,SUPERCAPACITORS ,COMPUTER simulation - Abstract
Flywheel energy storage can store large amounts of kinetic energy in its rotating parts, but its inertia restricts the rate of power exchange. On the other hand, there is supercapacitor with the ability of exchanging large amounts of instantaneous power. Therefore, the combination of these two systems can significantly improve the dynamic response of conventional flywheel energy storage. This paper proposes a novel design for this combined system in which supercapacitors are located inside the rotating disk. Therefore, supercapacitors can significantly improve the dynamic performance of the flywheel energy storage with trivial effects on its size and weight. Moreover, the ability of rotating supercapacitors to store electrical as well as kinetic energy increases the energy storage capacity of the proposed flywheel energy storage. This developed system with its improved performance can be widely employed instead of the conventional flywheel energy storage in various applications. In this paper, the proposed structures with built-in rotating supercapacitors are mechanically analyzed by CATIA and ABAQUS. In addition, the developed flywheel energy storage, which is equipped with a permanent magnet synchronous machine and its modified indirect vector controller, is simulated in MATLAB/Simulink under various conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
6. A novel and unified approach for averaged channel capacity and averaged effective capacity analyses of diversity combining and multihop transmission schemes in flat fading environments.
- Author
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YILMAZ, Ferkan and ALOUINI, Mohamed-Slim
- Subjects
CHANNEL capacity (Telecommunications) ,SIGNAL-to-noise ratio ,ELECTRIC lines ,COMPUTER simulation ,NUMERICAL analysis - Abstract
In this paper, we introduce an L
p -norm aggregation to present a signal-to-noise ratio expression unified not only for such diversity combining schemes as equal-gain combining, maximal-ratio combining, and selection combining, but also for such transmission techniques as multihop transmission. Accordingly, we propose two moment-generating function-based approaches that both respectively unify the exact analyses of the averaged channel capacity and averaged effective capacity over generalized fading channels with respect to the diversity combining and multihop transmission schemes. Finally, the mathematical formalism is illustrated by numerical special cases and verified by simulations. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
7. On the outage performance of SWIPT-NOMA-CRS with imperfect SIC and CSI.
- Author
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KARA, Ferdi
- Subjects
WIRELESS power transmission ,TIMESHARE (Real estate) ,ENERGY harvesting ,COMPUTER simulation ,SYSTEM failures - Abstract
In this paper, a nonorthogonal multiple access based cooperative relaying system (NOMA-CRS) is considered to increase spectral efficiency. Besides, the simultaneous wireless information and power transfer (SWIPT) is proposed for the relay in NOMA-CRS. In SWIPT-NOMA-CRS, three different energy harvesting (EH) protocols, power sharing (PS), time sharing (TS) and ideal protocols are implemented. The outage performances of the SWIPT-NOMA-CRS are studied for all three EH protocols. In the analysis, to represent practical/reasonable scenarios, imperfect successive interference canceler (SIC) and imperfect channel state information (CSI) are taken into consideration. The derived outage probability (OP) expressions are validated via computer simulations. Besides, the OP for the benchmark scheme, NOMA-CRS without EH, is also derived under imperfect SIC and CSI. Based on extensive simulations, it is revealed that the SWIPT-NOMA-CRS outperforms NOMA-CRS without EH. Finally, the effects of all parameters on the outage performance of the SWIPT-NOMA-CRS are discussed and for the given scenarios, the optimum PS factor, TS factor and power allocation coefficients are demonstrated. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
8. Exact and nonstandard finite difference schemes for the Burgers equation B(2, 2).
- Author
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KÖROĞLU, Canan and AYDIN, Ayhan
- Subjects
FINITE differences ,BURGERS' equation ,COMPUTER simulation - Abstract
In this paper, we consider the Burgers equation B(2, 2) . Exact and nonstandard finite difference schemes (NSFD) for the Burgers equation B(2, 2) are designed. First, two exact finite difference schemes for the Burgers equation B(2, 2) are proposed using traveling wave solution. Then, two NSFD schemes are represented for this equation. These two NSFD schemes are compared with a standard finite difference (SFD) scheme. Numerical results show that the NSFD schemes are accurate and efficient in the numerical simulation of the kink-wave solution of the B(2, 2) equation. We see that although the SFD scheme yields numerical instability for large step sizes, NSFD schemes provide reliable results for long time integration. Local truncation errors show that the NSFD schemes are consistent with the B(2, 2) equation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
9. Quasi-physical modeling of robot IRB 120 using Simscape Multibody for dynamic and control simulation.
- Author
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Le Ngoc TRUC and Nguyen Tung LAM
- Subjects
DYNAMIC simulation ,ROBOTS ,COMPUTER simulation ,MATHEMATICAL models ,ROBOT control systems - Abstract
The mathematical model of robot that is used to design control algorithms is mostly reused in numerical simulations as a virtual plant. The use of same model for both control design and simulation tasks makes the outcome idealized. Consequently, the effectiveness and feasibility of designed control methodologies when applied in practice seem to be questionable. The paper presents the quasi-physical modeling of a 6-DOF robot using MATLAB/Simscape Multibody for dynamic and control simulation. The bodies of the robot are assembled into a physical network with connections that represent physical domains. The dynamical manners of the quasi-physical model are close to that of real robot manipulators. This model can be exploited to verify the accuracy of mathematical models. After designing process, the control laws are validated with this model instead of an ideal mathematical model or an actual expensive prototype. The efficiency of the proposed modeling approach is demonstrated through the dynamic and control simulation of robot IRB 120. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Global stabilization of a class of fractional-order delayed bidirectional associative memory neural networks.
- Author
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Zhanying YANG, Xiaoyun TANG, and Jie ZHANG
- Subjects
STABILITY theory ,LYAPUNOV stability ,MEMORY ,COMPUTER simulation - Abstract
This paper focuses on the stabilization problem of a class of fractional-order bidirectional associative memory neural networks with time delays. Based on feedback control, a sufficient condition is derived to achieve the global stabilization of systems by using the fractional inequality, the Lyapunov stability theory, and the comparison principle. In particular, this kind of control scheme is proved to be robust in the presence of external disturbances when the feedback gains are sufficiently large. In addition, a condition is obtained to achieve the global quasi-stabilization of systems with some external disturbances, and the corresponding error bound is estimated. Finally, some numerical simulations are presented to verify the effectiveness of theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
11. A new failure protection algorithm for circuit breakers using the power loss of switching arc incidents.
- Author
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FEIZIFAR, Behnam and USTA, Ömer
- Subjects
OCEAN waves ,FLASHOVER ,COMPUTER simulation ,ALGORITHMS - Abstract
The principal function of circuit breakers (CBs) is to isolate a portion of the power network from the rest of it in a timely manner following an opening command. Any failure in the opening operation of CBs, especially following a fault condition, will almost certainly result in a catastrophic event. Therefore, the issue of failure detection of CBs is essential and has a vital role in power system protection. This paper presents a novel power-based algorithm for failure detection of CBs. The power loss of CBs due to an arcing event increases as the arcing time gets longer. The arcing time of CBs increases with defective operations originating from any failure or malfunction for different reasons. The proposed method uses the power difference between the input and output terminals of CBs to calculate the power loss due to an arcing event, which can then be used to estimate the arcing energy. A trip signal is initiated whenever the estimated arcing energy for a single opening operation reaches a predefined trip level, which shows a failure in CB operation. This predefined trip value is related to the integration of the maximum power capacity of the CB during an opening operation time. Computer simulation studies conducted to analyze the performance of the proposed technique demonstrate that the algorithm is capable of discriminating between normal and abnormal arcing energies and thus identifying malfunctions or failures in the opening operations of CBs. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
12. Fast nonsingular terminal decoupled sliding-mode control utilizing time-varying sliding surfaces.
- Author
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YORGANCIOĞLU, Ferhun and REDIF, Soydan
- Subjects
SLIDING mode control ,STEADY-state responses ,NONLINEAR systems ,COMPUTER simulation ,PENDULUMS - Abstract
In this paper, a fast form of nonsingular, terminal, decoupled, sliding-mode control, which utilizes timevarying sliding surfaces, is proposed for a class of fourth-order, single-input, multioutput, nonlinear systems. The novel control law features a fast term, in the manner of fast terminal sliding-mode control, which markedly improves the finite-time sliding-mode convergence speed near zero. Numerical simulation results, which are illustrated with a cartpole inverted pendulum system and a ball-beam system, demonstrate that the proposed control law achieves, in general, favorable transient response and lower steady-state errors compared to state-of-the-art decoupled terminal sliding-mode control methods. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
13. On the stability of inverse dynamics control of flexible-joint parallel manipulators in the presence of modeling error and disturbances.
- Author
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İDER, Sıtkı Kemal, KORKMAZ, Ozan, and DENİZLİ, Mustafa Semih
- Subjects
PARALLEL robots ,ROBOTIC trajectory control ,ERROR analysis in mathematics ,COMPUTER simulation ,STABILITY theory - Abstract
Inverse dynamics control is considered for flexible-joint parallel manipulators in order to obtain a good trajectory tracking performance in the case of modeling error and disturbances. It is known that, in the absence of modeling error and disturbance, inverse dynamics control leads to linear fourth-order error dynamics, which is asymptotically stable if the feedback gains are chosen to make the real part of the eigenvalues of the system negative. However, when there are modeling errors and disturbances, a linear time-varying error dynamics is obtained whose stability is not assured only by keeping the real parts of the frozen-time eigenvalues of the system negative. In this paper, the stability of such systems is investigated and it is proved that the linear time-varying system can be rendered stable by selecting the feedback gains such that the variation of the system becomes sufficiently slow. To illustrate the performance of the control method, deployment motion of a 3-RPR planar parallel manipulator subject to impact is simulated. For the impact model, the impulse-momentum and the coefficient of restitution equations for the system are derived. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
14. Evaluation of power system robustness in order to prevent cascading outages.
- Author
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HAJBANI, Farnaaz, SEYEDI, Heresh, and ZARE, Kazem
- Subjects
ELECTRIC power systems ,CASCADE converters ,ELECTRICAL load ,ROBUST statistics ,COMPUTER simulation - Abstract
Power system robustness against overload condition is a challenging issue in the fields of power system planning and operation. In this paper, two indices are proposed to evaluate power system robustness. The proposed indices are used to identify critical lines whose failure is due to overload, leading the power system to cascading outages and blackout. The first proposed index is a linear index. The second index is based on graph theory metrics. To prevent cascading outages, system robustness is calculated for all N - 1 and N - 2 contingencies. The lines whose outages lead to the smallest robustness values are considered as critical lines. The proposed indices are validated by applying to the IEEE 118-bus test system. Simulation results demonstrate the capability of both indices in identifying critical lines. Therefore, the purposed indices could be used as a reliable metric to apply preventive actions against possible cascading outages and blackouts. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. Electron energy loss spectroscopy simulation by a frequency domain surface integral equation solver.
- Author
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UYSAL, İsmail Enes
- Subjects
ELECTRON energy loss spectroscopy ,COMPUTER simulation ,FREQUENCY-domain analysis ,INTEGRAL equations ,PROBLEM solving - Abstract
Plasmonic nanoparticles have been mostly studied using conventional light sources. Recently, electron energy loss spectroscopy (EELS) has started to be used to analyze plasmonic nanoparticles where incident electromagnetic fields are created by swift electrons. To accurately simulate EELS experiments, several numerical methods have been adapted. In this paper, a frequency domain surface integral equation (FDSIE) solver is modified to simulate EELS for plasmonic nanoparticles of gold and silver. Accuracy and versatility of the proposed FDSIE solver are shown by several numerical examples and compared to existing numerical, analytical, and experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Sensorless second-order switching surface for a three-level boost converter.
- Author
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MESSIKH, Tarek, RAHIM, Nasrudin Abd, and MEKHILEF, Saad
- Subjects
ELECTRICAL load ,SWITCHING circuits ,SENSORLESS control systems ,CONVERTERS (Electronics) ,COMPUTER simulation - Abstract
This paper proposes a sensorless second-order switching surface to control a three-level boost converter (TLBC). A predictive current method is proposed to reduce the number of sensors in the normal second-order switching surface method. Based on a developed model of the TLBC, the current is estimated and a switching surface is formulated in the state-energy plane. Simulation and hardware tests are carried out to verify the viability and the effectiveness of the proposed control technique. Results obtained show a good performance of the converter in term of DC-bus balancing and fast dynamic response under sudden load change. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
17. Grid-connected quasi-z-source inverter with battery.
- Author
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SHINDE, Umesh, KOTTAGATTU, Sagar, KADWANE, Sumant, and GAWANDE, Snehal
- Subjects
SWITCHING circuits ,COMPUTER simulation ,ELECTRIC power distribution grids ,DIRECT currents ,ELECTRICAL harmonics - Abstract
Grid-connected inverters are now increasingly used in distributed microgrid and smart-grid applications. The advantages of a quasi-Z-source inverter (QZSI), like single-stage operation, lower component rating, continuous input current, and common DC rail, led to an investigation of this converter for grid-connected applications. This paper presents a grid-connected QZSI with both AC and DC side controls. A new battery-charging configuration is also suggested across the capacitor through which the DC side control loop is regulated. Fast dynamic response and reduced harmonics are demonstrated through simulation and experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
18. A comparative study on different types of metamaterials for enhancement of microstrip patch antenna directivity at the Ku-band (12 GHz).
- Author
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TÜTÜNCÜ, Bilal, TORPİ, Hamid, and URUL, Bülont
- Subjects
- *
MICROSTRIP transmission lines , *ELECTROMAGNETISM , *WIRELESS communications , *COMPUTER simulation , *ELECTROMECHANICAL analogies - Abstract
This paper proposes improving the directivity of microstrip patch antennas (MPAs) by using metamaterials. Four different metamaterial types are used as a at lens in front of the MPA, respectively, which are tuned to 12 GHz (Ku-band) resonance frequency. Thus, it can be decided which metamaterial is more proper for antenna directivity enhancement at this band. One additional new metamaterial structure is proposed in this paper, which is called a Euro-shaped resonator, and other metamaterials used are the triangular split ring resonator, symmetrical ring structure, and split ring resonator. The permeability and permittivity of metamaterials are extracted from the S parameters by using a robust method. Microwave Studio by Computer Simulation Technology is used for modeling and simulation. The MPA and metamaterials are fabricated, and measurements are performed in the Yíldíz Technical University RF and Microwave Laboratory. It is observed that measured results are in close agreement with the computer simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
19. A novel hybrid approach based on a chaotic cloud gravitational search algorithm to complicated image template matching.
- Author
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Weijia CUI and Yuzhu HE
- Subjects
- *
SEARCH algorithms , *TEMPLATE matching (Digital image processing) , *DATA mining , *CLOUD computing , *COMPUTER simulation - Abstract
Template matching is the process of accurately extracting the interesting regions in a source image according to reference templates. In this paper, the gravitational search algorithm (GSA) is employed as a novel search strategy for template matching. However, the basic GSA is easily trapped in a local optimum and has a poor exploitation ability. In this paper, to enhance the optimization performance of GSA, a novel cross-search strategy based on chaotic global search (CGS) and cloud local search (CLS) is incorporated into GSA. The new variant is named chaotic cloud GSA (CCGSA). CGS makes full use of the ergodicity of chaos theory to improve global search ability and to avoid premature convergence. Inspired by the randomness and stable tendency of the normal cloud model, CLS was formed to realize a refined exploitation in the neighborhood of the current best solution; therefore, it can enhance optimization efficiency. Comparative experiments on six composite benchmark functions indicate that CCGSA convergence performance is superior to that of two advanced variants of GSA. Moreover, when applied to template matching, CCGSA performs better than the other selected intelligent optimization algorithms. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
20. Marine effects on vertical electrical soundings along shorelines.
- Author
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ULUGERGERLİ, Emin Uğur
- Subjects
DIRECT currents ,SHORELINES ,INVERSION (Geophysics) ,COMPUTER simulation ,ELECTRICAL resistivity - Abstract
Onshore applications of direct current resistivity (DCR) along shorelines suffer a short-circuit-like phenomenon due to electrical current flowing through a more conductive body of water rather than ground. Our study of the numerical simulation of DCR data with a three-dimensional forward model demonstrated that the apparent resistivity was reduced as a function of the sea depth and the distance of measurement site to the shoreline. Furthermore, it was concluded that the "marine effects" on DCR data (i.e. reduction in apparent resistivity) become nonnegligible as the ratio of half-electrode expansion (AB/2) to the distance to the shoreline is larger than one. The reduction in apparent resistivity reaches its highest levels as the ratio approaches ten. Our survey conducted along the coastal line of Northwest Turkey clearly showed that if the "marine effects" are left untreated, one- or two-dimensional inversion yields incorrect resistivities for underlying units and therefore undermines the credibility of survey results. In the paper suggestions are made to handle such situations. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. A new algorithm for avoiding maloperation of transformer restricted earth fault protection caused by the transformer magnetizing inrush current and current transformer saturation.
- Author
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KRSTIVOJEVIC, Jelisaveta and DJURIC, Milenko
- Subjects
- *
ELECTRIC transformers , *ELECTRIC fault location , *ALGORITHMS , *CURRENT transformers (Instrument transformer) , *COMPUTER simulation - Abstract
Owing to current transformer (CT) saturation caused by a decaying direct current component in the magnetizing inrush current, the restricted earth fault (REF) protection of a power transformer could maloperate during magnetizing inrush. This paper presents a new transformer restricted earth fault relay algorithm that can prevent false relay tripping and provide proper action during the energization of a faulty transformer. The integral of the product of the signals that are compared is calculated over 1 half-period of the signals. The performance of the proposed algorithm is tested and verified using a large number of transformer energization trials and fault cases. The signals required for testing of the algorithm were obtained by laboratory measurements, and then the algorithm was tested off-line. The inuence of different levels of CT saturation due to different remanent uxes in CT cores during power transformer energization was investigated. By applying computer simulations, the signals required for algorithm testing were generated. The investigation results presented in this paper show that the new algorithm provided sensitive protection for the power transformer for phase to ground faults and high security and stability during magnetizing inrush conditions in conjunction with CT saturation. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
22. Modeling and simulation of sensorless control of four-leg inverter PMSM drives in the case of a single-phase open circuit fault.
- Author
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SALEH, Kamel and SUMNER, Mark
- Subjects
- *
INSULATED gate bipolar transistors , *FAULT tolerance (Engineering) , *PERMANENT magnet motors , *SYNCHRONOUS electric motors , *OPEN-circuit voltage , *COMPUTER simulation , *SENSORLESS control systems , *ELECTRIC inverters - Abstract
This paper introduces a new method to track the saliency of a permanent magnet synchronous motor (PMSM) motor fed by a 4-leg inverter in the case of a single-phase open circuit fault through measuring the dynamic current response of the motor line currents due to the insulated-gate bipolar transistor (IGBT) switching actions. In the case of a single-phase open circuit fault, a fault-tolerant control strategy that includes taking appropriate actions to control the 2 remaining healthy currents results in minor system performance degradation. The new strategy introduced in this paper includes software modifications only to the saliency tracking algorithm used in healthy mode in order to make it applicable to the reconfigured converter in the presence of a fault. The new method uses only the fundamental pulse width modulation (PWM) waveform (i.e. there is no modification to the operation of the 4-leg inverter), similar to the fundamental PWM method proposed for a 3-leg inverter. Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by fault-tolerant 4-phase inverter over a wide range of speeds under the case of a single-phase open circuit fault. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
23. Composite vector quantization for optimizing antenna locations.
- Author
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UYKAN, Zekeriya and JÄNTTI, Riku
- Subjects
- *
DATA transmission systems , *MATHEMATICAL optimization , *WIRELESS communications , *COMPUTER simulation , *ELECTROMECHANICAL analogies - Abstract
In this paper, we study the location optimization problem of remote antenna units (RAUs) in generalized distributed antenna systems (GDASs). We propose a composite vector quantization (CVQ) algorithm that consists of unsupervised and supervised terms for RAU location optimization. We show that the CVQ can be used i) to minimize an upper bound to the cell-averaged SNR error for a desired/demanded location-specific SNR function, and ii) to maximize the cell-averaged effective SNR. The CVQ-DAS includes the standard VQ, and thus the well-known squared distance criterion (SDC) as a special case. Computer simulations confirm the findings and suggest that the proposed CVQ-DAS outperforms the SDC in terms of cell-averaged "effective SNR". [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
24. Neural network-based adaptive tracking control for a nonholonomic wheeled mobile robot with unknown wheel slips, model uncertainties, and unknown bounded disturbances.
- Author
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NGUYEN, Tinh and Linh LE
- Subjects
- *
ARTIFICIAL neural networks , *AUTOMATIC control of mobile robots , *BACK propagation , *CLOSED loop systems , *COMPUTER simulation - Abstract
In this paper, an adaptive tracking controller based on a three-layer neural network (NN) with an online weight tuning algorithm is proposed for a nonholonomic wheeled mobile robot in the presence of unknown wheel slips, model uncertainties, and unknown bounded disturbances. The online weight tuning algorithm is modified from the backpropagation with an e-modification term required to assure that the NN weights are bounded. Preliminary neural network offline training is not essential for the weights. Thanks to this proposed controller, the desired tracking performance is achieved where position tracking errors converge to an arbitrarily small neighborhood of the origin regardless of their initial values. According to Lyapunov theory and LaSalle extension, the stability of the whole closed- loop system is ensured to obtain the desired tracking performance. Computer simulations are implemented to certify the validity of the proposed controller. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
25. ANN-based SHEPWM using a harmony search on a new multilevel inverter topology.
- Author
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CHABNI, Fayçal, TALEB, Rachid, and HELAIMI, M'hamed
- Subjects
- *
ARTIFICIAL neural networks , *ELECTRICAL harmonics , *ELECTRIC inverters , *COMPUTER simulation - Abstract
This article presents the application of the harmony search (HS) optimization algorithm for selective harmonic elimination PWM (SHEPWM) in a new topology of multilevel inverters with reduced number of electronic switching elements. The main objective of the harmonic elimination strategy is eliminating undesired low-rank harmonics in order to improve the quality of the output waveform. The harmonic elimination strategy is achieved by solving a system of nonlinear equations. In this paper harmony search optimization is applied using artificial neural networks (ANNs) on a new 21-level inverter topology. The algorithm is based on a music improvisation process. MATLAB programming software is used to develop a harmony search optimization program for harmonic elimination. A small-scale laboratory of the proposed 21-level inverter is built to validate the simulation results and to prove the efficiency of the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
26. Multiobjective distributed model predictive control method for facility environment control based on cooperative game theory.
- Author
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Huanliang XU, Zhaoyu ZHAI, Ke WANG, Shougang REN, and Haoyun WANG
- Subjects
- *
PLANT layout , *INDUSTRIAL efficiency , *COOPERATIVE game theory , *EVALUATION , *COMPUTER simulation - Abstract
In order to achieve better control performance within the facility environment, this paper proposes a distributed model predictive control method, aiming at increasing the control precision of actuators, reducing energy consumption and equipment loss at the same time. Regarding optimizing this facility environment model, it could be treated as a multiobjective optimization problem. Referring to the cooperative game theory, each objective is regarded as a gamer. Each gamer considers both its own interests and other gamers' interests to achieve a balanced result when cooperation is achieved. The simulation experiments illustrate that the proposed control method is able to adjust the parameters of the facility environment to a preset interval properly. Moreover, in this specific simulation environment, the proposed method achieves better performances than the single objective control method and traditional linear weighted multiobjective control method in most of the evaluation criteria. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
27. Application of reinforcement learning for active noise control.
- Author
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HOSEINI SABZEVARI, Seyed Amir and MOAVENIAN, Majid
- Subjects
- *
MACHINE learning , *ACTIVE noise control , *COMPUTER simulation , *REINFORCEMENT learning , *SIMULATION methods & models , *ACTIVE noise & vibration control - Abstract
Active noise control (ANC) systems are used to reduce the sound noise level by generating antinoise signals. M-Estimators are widely employed in ANC systems for updating the adaptive FIR filter taps used as the system controller. Observing the state-of-the-art M-estimators design shows that there is a need for further improvements. In this paper, a feedback ANC based on the reinforcement learning (RL) method is proposed. The sensitivity of the constant parameter in the RL method is checked. The effectiveness of the proposed method is proven by comparing the results with previous feedforward studies through computer simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
28. Double bow-tie FSS for X-band and Ku-band operations with its parametric analyses.
- Author
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ÇİĞDEM, Selma, TUNCA, Cihan, CAN, Sultan, and YILMAZ, Asım Egemen
- Subjects
- *
BANDWIDTHS , *HIGH frequency antennas , *FINITE element method , *COMPUTER simulation , *ELECTRICAL engineering - Abstract
This paper demonstrates double bow-tie frequency selective surface (FSS) geometry for X-band applications with a bandwidth value of 1.82 GHz and Ku-band applications with a bandwidth value of 3.44 GHz. Throughout this study, parametric analyses of the proposed structure are also performed. Alterations in the reection and transmission characteristics of this specially designed structure by virtue of defined variables are analyzed. Those variables are determined by considering the geometric and material properties of the proposed structure. To analyze the reection and transmission coefficients, two different simulators, namely the High Frequency Structure Simulator (ANSYS HFSS), which is based on the finite element method (FEM), and the Computer Simulation Technology Studio Suite (CST Studio Suite), which is based on the finite integration method (FIM), are used. The structure is validated via those two solvers. Good agreement is obtained by both solvers, and the results are compared in terms of frequency, return loss, insertion loss, and fractional bandwidth. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
29. Digital implementation of a constant frequency hysteresis controller for dual mode operation of an inverter acting as a PV-grid interface and STATCOM.
- Author
-
PRAKASH, Lenin, MEENAKSHI SUNDARAM, Arutchelvi, and DURAIRAJ, Kalyanraj
- Subjects
- *
ELECTRIC inverters , *IDEAL sources (Electric circuits) , *ELECTRIC power distribution grids , *HYSTERESIS , *COMPUTER simulation , *DISTRIBUTED power generation - Abstract
This paper presents a new constant frequency hysteresis current controller for the grid interface of a PVfed three-phase voltage source inverter (VSI) for a dual mode operation, feeding real power during the daytime and reactive power alone during nights, thereby acting as a STATCOM. The constant frequency is inherently achieved by means of digital implementation in a simplified manner without any complex manipulations to choose a variable band width; rather the hysteresis band varies as a natural consequence of selecting appropriate constant sampling frequency. Analytical proof is presented for the switching frequency to remain constant, without compromising on the performance indices. The design of the proposed controller for a grid-connected inverter operating in dual mode is presented, along with simulation results. The proposed controller is successfully implemented using a 1.1 kW PV array-fed inverter. The hardware results presented show the grid current harmonics complies with IEEE 1547 and has been achieved in a simpler means when compared to other existing techniques. The proposed controller is expected to be an attractive solution for grid-connected inverter applications including distributed generation, power quality, and drive applications. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
30. Optimization of PID parameters using BBBC for a multiarea AGC scheme in a deregulated power system.
- Author
-
KUMAR, Nagendra, KUMAR, Vishal, and TYAGI, Barjeev
- Subjects
- *
AUTOMATIC control systems , *ALGORITHMS , *COMPUTER simulation , *PID controllers , *PARAMETERS (Statistics) - Abstract
Automatic generation control (AGC) is an important service used for the secure and reliable operation of a power system. In this paper, a suitable AGC scheme for a deregulated environment has been studied for various load perturbation scenarios. A proportional integral derivative (PID) controller has been utilized to control the real power output of the generators. The optimal parameters of the PID controller have been determined using the big bang big crunch (BBBC) algorithm, (BBBC-PID). The performance of the BBBC-PID controller has been checked on three different sized multiarea power systems. The results obtained with the applied algorithm have also been compared with the results of other algorithms, namely imperialistic competition algorithm (ICA) and harmony search (HS). MATLAB/Simulink was used as a simulation tool for this study. The results show the superiority of the BBBC-PID over the others. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
31. Adaptive speed observer with disturbance torque compensation for sensorless induction motor drives using RT-Lab.
- Author
-
KRISHNA, Mohan and DAYA, Febin
- Subjects
- *
PERFORMANCE of induction motors , *SENSORLESS control systems , *TORQUE , *COMPUTER simulation , *ROBUST control , *MECHANICAL models - Abstract
This paper presents an improved version of the extended Luenberger observer with joint estimation of rotor speed and disturbance torque. The mechanical model of the induction motor is also utilized for the estimation of disturbance torque to add to the robustness of the observer. The estimated disturbance torque is treated as a model disturbance and physically incorporated into the observer state dynamic equation. The dynamic performance and efficacy of the modified observer is tested for variations in external load and inertia coefficient in the mechanical model. The above observer model is first built offline, using MATLAB/Simulink block sets, and simulated. Further, the offline simulated results are validated in real time by incorporating RT-Lab block sets into the Simulink model and implementing it in the 0P4500 real-time simulator developed by Opal-RT. The implementation of the above concept in a relatively new real-time environment adds more strength to the offline findings and provides an exact replica of how the actual physical system would behave. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
32. Design of low power system on programmable chip for video zoom-in processing.
- Author
-
TOUIL, Lamjed, KECHICHE, Lilia, and OUNI, Bouraoui
- Subjects
- *
INTEGRATED circuit design , *VIDEO processing , *COMPUTER simulation , *EMBEDDED computer systems , *PARAMETERS (Statistics) , *ELECTRIC power consumption - Abstract
Today, power consumption presents a critical issue when designing embedded systems. It has become a key factor in a product's success when being marketed, especially for mobile systems. In this paper, we have developed a typical design for video zoom-in processing with low power consumption. The proposed design has been implemented on the Xilinx Virtex-5 with the integration of different important resources like embedded processor, embedded memory, MPMC, DDR, and various interfaces. The design results show a significant gain in power at the simulation level as well as the physical one. In addition, the proposed design provides an important gain in power without degrading other parameters such as frequency, area, and others. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
33. A designed converter for minimizing SRM torque ripple with controlled boost capacitor automatically.
- Author
-
SAMANI, Loghman, ABDOLHAMIDI, Mahdi, RASHIDI, Amir, and SAGHAIANNEZHAD, Sayed Morteza
- Subjects
- *
CAPACITORS , *CONVERTERS (Electronics) , *TORQUE control , *RELUCTANCE motors , *COMPUTER simulation , *AUTOMATIC control systems - Abstract
Direct instantaneous torque control (DITC) is one way of controlling torque in switched reluctance motors. Despite the presence of DITC control, torque ripple at nominal or higher speeds is considerable due to the back emf increasing. To overcome this drawback, many converters have been proposed. In most convertors proposed for fast excitation in DITC, controlling of boost capacity is an important problem. This paper presents a DITC for a switched reluctance motor using a proposed converter to reduce the torque ripple with controlled boost capacitor automatically. The proposed converter reduces the torque ripple at rated or higher speeds and no controller requires controlling the boost capacitor. The proposed converter is compared with an asymmetric one via simulation results using MATLAB and experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Shunt active power filter control for compensating current power quality problems in three-phase three-wire systems based on an adaptive notch filter.
- Author
-
TABATABAEI, Seyed Hossein, MOSLEHI BAJESTAN, Mehran, and JALILIAN, Alireza
- Subjects
- *
ELECTRIC power filters , *ELECTRIC currents , *ADAPTIVE control systems , *THREE-phase alternating currents , *COMPUTER simulation - Abstract
In this paper, a scheme is presented for properly compensating current power quality problems in a network. In this method, only by measuring grid current and using an adaptive notch filter (ANF), a reference sinusoidal current that is in phase with the grid voltage is created for the control system. Using ANFs guarantees the proper efficiency of the network when its frequency changes. A proportional controller and a resonance bank along with pulse width modulation are used in the shunt active power filter (SAPF) control system. One of the features of the resonant controller is its extremely high open-loop gain at its resonance frequency. This high gain causes the controller to accurately track the harmonic components. Simulations are carried out in MATLAB software under various conditions of load and network voltage, such as unbalanced and distortional voltage and changing load. These simulations verify the capabilities of this scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
35. Design of fir filters using exponential--Hamming window family.
- Author
-
AVCİ, Kemal
- Subjects
- *
FINITE impulse response filters , *EXPONENTIAL functions , *HAMMING distance , *COMPUTER simulation , *DIGITAL filters (Mathematics) - Abstract
In this paper, a new two-parameter window obtained by the combination of two windows, known as exponential and Hamming, is proposed and applied for the design of finite impulse response (FIR) digital filters. First of all, the quality of the proposed window is analyzed in terms of window spectral parameters and then compared with other two-parameter windows, namely Kaiser, cosh, and exponential. The window simulation results show that the proposed window can provide better ripple ratio than other windows for fixed window length and mainlobe width. Secondly, the performance of the proposed window is analyzed in digital filter design. The filter numerical comparison with Saramaki, Kaiser, Dolph-Chebyshev, cosh, and exponential windows confirms that the filter designed by the proposed window can exhibit a better filtering performance compared to well-known two-parameter windows in the literature because it can provide better minimum stopband attenuation for fixed filter length and transition width. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
36. Gravitational search algorithm for determining controller parameters in an automatic voltage regulator system.
- Author
-
DUMAN, Serhat, YÖRÜKEREN, Nuran, and ALTAŞ, İsmail H.
- Subjects
- *
SEARCH algorithms , *PID controllers , *GRAVITATION , *VOLTAGE regulators , *HEURISTIC algorithms , *COMPUTER simulation - Abstract
This paper presents optimal tuning of the controller parameters of a proportional-integral-derivate (PID) controller for an automatic voltage regulator (AVR) system using a heuristic gravitational search algorithm (GSA) based on mass interactions and Newton's law of gravity. The determination of optimal controller parameters is considered an optimization problem in which different performance indexes and a performance criterion in the time domain have been used as objective functions to test the performance and effectiveness of the GSA. In the determining process of the parameters, the designed PID controller with the proposed approach is simulated under different conditions and the performance of the controller is compared with those reported in the literature. From the numerical simulation results it is clear that the GSA approach is successfully applied to reveal the performance and the feasibility of the proposed controller in the AVR system. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
37. Speciation-based genetic algorithm in analog circuit design.
- Author
-
KARCİ, Hasari, TOHUMOĞLU, Gülay, and NACAROĞLU, Arif
- Subjects
- *
ANALOG circuits , *GENETIC algorithms , *GAUSSIAN processes , *COMPUTER simulation , *CONFIDENCE intervals ,DESIGN & construction - Abstract
This paper presents a speciation procedure that improves the local search capability of the genetic algorithm in analog circuit design. There is no need for additional circuit simulation in order to apply this procedure. The procedure is tested in Gaussian, sigmoid, cube, and square circuit design problems. Two sets of 125 simulations with the same seed values are performed for each problem using both the proposed procedure and the canonical genetic algorithm. The simulation results show that the method is statistically better than the canonical genetic algorithm, which suffers from bad locality. The effects of the population size and speciation threshold coefficient on the performance of the speciation algorithm are investigated. Confidence intervals of the simulation results are calculated. The results show that the speciation procedure improves the quality of solutions with at least 99% confidence, and the effectiveness of the method, which is statistically determined, increases in small populations. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
38. Optimization of automatic steering control on a vehicle with a steer-by-wire system using particle swarm optimization.
- Author
-
HUNAINI, Fachrudin, ROBANDI, Imam, and SUTANTRA, Nyoman
- Subjects
- *
STEERING gear , *AUTOMATIC control systems , *AUTOMOBILE driving , *PARTICLE swarm optimization , *COMPUTER simulation - Abstract
This paper presents a simulation of the automatic steering control system on a vehicle model using particle swarm optimization (PSO) to optimize the parameters of the control system. The control system involves fuzzy logic control (FLC) and proportional-integral-derivative (PID) control working in a cascade; the main control (FLC) is used to control lateral motion, and the secondary control (PID) is an enhancement to control the yaw motion in vehicle models representing 10 degrees of freedom of the vehicle dynamics system. Optimization by PSO is carried out simultaneously on both control systems. On FLC it is done by setting the width and the center point of the membership function (MF) in the input and output FLC so that the optimal composition of the MF parameter is obtained. The optimization process also determines the constants of optimal gain in the PID control. Testing is done through software in the loop simulation. Based on the test results it can be stated that FLC and PID control tuned by PSO can steer the vehicle rate well in accordance with desired trajectory and the vehicle motion can always be maintained at the specified path. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
39. Performance analysis of a low-cost current-source 1-ph grid-connected PV inverter.
- Author
-
ERTAŞGIN, Gürhan, Wen Liang SOONG, and ERTUGRUL, Nesimi
- Subjects
- *
SMART power grids , *ELECTRIC inverters , *PHOTOVOLTAIC power systems , *DIRECT current circuits , *COMPUTER simulation , *HARMONIC distortion (Physics) - Abstract
This paper investigates the design and performance of a 150 W single-phase current-source grid-connected inverter topology that is based on a PV array and DC link inductor acting as a constant-current source. The inverter is implemented using a single boost switch, an H-bridge inverter, and a CL output filter. The inverter output current is simply controlled using the boost switch and open-loop or feedforward control. The dark I-V configuration is used to simulate two series PV modules. Comprehensive test results are obtained to validate the computer simulation results. Furthermore, the proposed inverter's ability to deliver a sinusoidal current to the grid while meeting the appropriate standards, i.e. total harmonic distortion and power factor requirements, is also examined for various modulation index values and irradiances. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
40. Numerical simulations of traveling waves in a counterflow filtration combustion model.
- Author
-
ÖZBAĞ, Fatih
- Subjects
COMBUSTION kinetics ,COMBUSTION ,REACTION-diffusion equations ,BOUNDARY value problems ,COMPUTER simulation ,FINITE differences ,POROUS materials - Abstract
We focused on traveling combustion waves that appear in a simplified, one-dimensional combustion model in porous media. The system we consider is a reaction-convection-diffusion system that can be reduced into two-dimension in order to prove traveling waves by phase plane analysis. In previous studies combustion wave velocity was assumed positive and their existence was proven. Also, all possible wave sequences that solve boundary value problems on infinite intervals with constant boundary data were identified. In this study, we generalize the previous work by including the case of negative combustion wave speed and taking the assumption that oxygen is carried faster than temperature. Moreover, we extend the classification of all possible wave sequences by performing numerical simulations using finite difference scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
41. An implementable approach in order to model a nonideal incremental encoder in speed measurement studies.
- Author
-
MAAREF, Mahdi and REZAZADEH, Alireza
- Subjects
- *
SPEED measurements , *COMPUTER simulation , *DECODERS & decoding , *VIBRATION (Mechanics) , *MATHEMATICAL models , *PARAMETERS (Statistics) - Abstract
Incremental encoders have attracted significant attention to measure motor speed worldwide. Due to the advantages of incremental encoders a noticeable percentage of Servo system drives have been built based on these sensors. The nonideality of encoders, especially mechanical misalignments, is one of their most important problems, affecting the precision of calculations. In the current paper we present an analytical formula to model the nonideal incremental encoder and calculate both the frequency and magnitude of vibrations due to this nonideality. Moreover, a nonideality identity parameter of the encoder is defined. This parameter can be used for quality assurance purposes. Moreover, it is possible to design exible filters for measured speed based on this parameter, especially in low resolution encoders. The simulation and experimental results corroborate the precision of the proposed method in a wide range of speeds. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
42. Study of MAC routing in the BPLC P1901 access network: fixed vs. adaptive approach.
- Author
-
GOGIC, Asmir, MUJCIC, Aljo, ÇAVDAR, İsmail Hakkı, ZAJC, Matej, and SULJANOVIC, Nermin
- Subjects
- *
CARRIER transmission on electric lines , *ACCESS control of computer networks , *ROUTING algorithms , *BROADBAND communication systems , *COMPUTER simulation , *MATHEMATICAL models - Abstract
In this paper we propose an improved adaptive media access (MAC) layer routing algorithm for the broadband power line communication (BPLC) access network founded on the fixed basic approach routing algorithm, which is integrated within the IEEE P1901 standard. The proposed adaptive algorithm incorporates a new dynamically scaled threshold for the selection of the next hop station based on the information from the physical layer. Furthermore, the procedures for the route and the time allocation modifications during the connection setup and later adjustments are developed. Simulation of the new adaptive and existing fixed routing algorithm is performed on the model of a realistic BPLC network using the OMNeT++-based BPLC cross-layer simulator BPlcSim. The simulation results showed that the adaptive routing algorithm outperforms the fixed routing in all aspects, since each station can perform routing functions and make the selection of the most reliable next hop station. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
43. Robust speed controller design for induction motors based on IFOC and Kharitonov theorem.
- Author
-
MOAVENI, Bijan and KHORSHIDI, Mojtaba
- Subjects
- *
PID controllers , *ROBUST control , *INDUCTION motors , *COMPUTER simulation , *FIELD orientation principle ,DESIGN & construction - Abstract
In this paper, robust PI controllers are designed to control the speed of induction motors based on a vector control strategy. The design methodology defines the robust stability and robust performance regions in the kp - ki (PI controller coefficients) plane using the Kharitonov theorem. In the control system design procedure, a nonlinear induction motor is modeled as an uncertain linear model. The procedure of modeling the uncertainties is presented. The required scientific foundations for designing a robust PI controller are also introduced in the general case while the necessary equations are derived. In the final step, the design procedure for a special motor is presented thoroughly. The simulation results indicate the efficiency of the method. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
44. On the local and global stability of an sirs epidemic model with logistic growth and information intervention.
- Author
-
ÇAY, İrem
- Subjects
BASIC reproduction number ,COMPUTER simulation ,LYAPUNOV functions - Abstract
In this study, we investigate an susceptible-infected-recovered-susceptible (SIRS) epidemic model with logistic growth and information intervention. Firstly, the basic reproduction number R
0 is defined and the main results are given in terms of local stability. Then, sufficient conditions for the global stability of endemic equilibrium are obtained. Finally, some numerical simulations are given to validate our theoretical conclusions. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
45. Hypergeometric distribution of the number of draws from an urn with two types of items before one of the counts reaches a threshold.
- Author
-
GONZÁLEZ-SANTANDER, Juan Luis
- Subjects
HYPERGEOMETRIC series ,HYPERGEOMETRIC functions ,RANDOM variables ,URNS ,STANDARD deviations ,COMPUTER simulation - Abstract
We consider an urn with R elements of one type and B elements of other type. We calculate the probability distribution ... wherein the random variable s is the number of draws from the urn until we reach nR elements of type R or nB elements of type B. We calculate the mean value
and the standard deviation σ of ... in terms of hypergeometric functions. For nR = nB and B = R, we reduceand σ in terms of elementary functions. Also, the normalization condition leads to a new hypergeometric summation formula involving 3F2 terminating series with unity argument. For nR = nB , we provide an alternative proof of this summation formula using q-hypergeometric functions. As a consistency test, computer simulations have been performed to confirm the analytical results obtained. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
46. Thyristor-based "phase hopping" frequency conversion technique.
- Author
-
Zhengwang XU, Jiarui ZHANG, Yuchun YI, Cheng CHEN, Jiaqi YU, Wei MEI, and Daiwei FENG
- Subjects
THYRISTORS ,FREQUENCY changers ,ENERGY consumption ,HARMONIC analysis (Mathematics) ,COMPUTER simulation - Abstract
This study proposes a new AC/AC "phase hopping" frequency conversion method based on the analyses of the disadvantages of the conventional cosine wave-crossing method. The advantages of this new method include no circulating current, no dead time, and an output frequency close to the power frequency. This study also introduces the basic principles of the "phase hopping" method and analyzes these principles combined with the voltage phase-changing comparison to that of the cosine wave-crossing method. The "phase hopping" principles are used to analyze the generation of thyristor trigger pulses, including the generation time and duration. A simulation is conducted in MATLAB, and the simulation output waveform and harmonic analysis results are then obtained. The proposed approach is verified on an experimental platform. Consequently, the results are in good agreement with those of the theoretical and simulation analyses. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
47. Improving side lobe level of X-band microstrip Rotman lens utilizing nonuniform distribution of output ports.
- Author
-
ZAREIAN-JAHROMI, Ehsan, BASIRI, Raheleh, SALEHI, Parvin, and KARAMI, Hamidreza
- Subjects
ROTMAN lenses ,MICROSTRIP transmission lines ,ATTENUATION (Physics) ,COMPUTER simulation ,ELECTRICAL engineering - Abstract
A new microstrip Rotman lens with enhanced side lobe level (SLL) is proposed for X-band applications. A proper nonuniform distribution of the initial width of output ports is considered to improve the SLL. The benefit of SLL improvement is not based on using additional attenuators or amplifiers at the output ports. Moreover, an analytical background is presented to investigate the resulting SLL of the proposed structure. The advantage of SLL enhancement is obtained at all noncorner scan angles considering 10 GHz operating frequency. As the middle input port is excited, more than 3 dB of SLL enhancement is achieved at 10 GHz. The proposed structure provides even more accurate scan angles than those of the conventional Rotman lens. The designed structure is simulated using full-wave HFSS 15 software. The comparison between simulated results and measurements of the fabricated proposed Rotman lens shows good agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
48. A low-complexity RARE-based 2-D DOA estimation algorithm for a mixture of circular and strictly noncircular sources.
- Author
-
SHABIR, Kashif, HASAN AL MAHMUD, Tarek, Rui ZHENG, and Zhongfu YE
- Subjects
GENETIC algorithms ,ESTIMATION theory ,COMPUTATIONAL complexity ,COMPUTER simulation ,BIOSENSORS - Abstract
A new rank reduction (RARE)-based two-dimensional (2-D) direction of arrival (DOA) estimation algorithm is proposed considering a mixture of circular and strictly noncircular sources. To enhance array aperture, a geometry of three uniform linear arrays is considered and then treated as displaced arrays from a virtual array using a simple linear transformation. The received data and the conjugated counterpart are combined together, exploiting the noncircular property. Both sources can be estimated separately by designing and exploiting the distinctive nature of circular and noncircular steering vectors. However, a 2-D spectrum search would lead to a high computational complexity burden. To reduce this high computational complexity burden, a novel RARE-based method is proposed, which plays a vital role by decomposing 2-D observation space into two successive 1-D peak search functions. The proposed method has some distinctive advantages: it can enhance the array aperture utilization, it can provide better estimation accuracy when mixed sources are greater than the number of sensors, it can estimate a larger number of mixed sources than the number of sensors, and finally it can automatically pair 2-D DOAs without any complicated pairing formulation. Extensive simulation results are provided to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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