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International Review on
Modelling and Simulations
February 2014
(Vol. 7 N. 1)

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    An Enhanced Ultra Capacitor Interface Circuit Based Bidirectional Soft Switching Converter

    by B. Stalin, T. S. Sivakumaran


    Abstract - Nowadays the bidirectional PWM DC-DC converter connected with the storage system has a prominent option of the electrical appliances. In this soft switching techniques are used, because the soft switching PWM converter is defined as the combination of converter topologies and switching strategies that result in Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS). In soft switching based storage system, the efficiency of system is depends on the size and cost; it can be increased by a combination of batteries and ultra capacitors. The ultra capacitor voltage changes during charge and discharge modes, therefore an interface circuit is required between the ultra capacitor and the battery. Also, the leakage current of ultra capacitor is high so the voltage imbalance problem has to be occurred. This paper describes an enhanced ultra capacitor interface circuit based bidirectional soft switching converter. The circuit of the proposed topology will be enhanced which will be based on the bidirectional conversion efficiency. The proposed circuit topology will be preferred for maintaining the conversion efficiency during static and dynamic working condition. Also, the working mode of both buck and boost conversion will be analyzed by the equivalent circuit model. The ultra capacitor leakage current will be reduced by the interface circuit which will utilize the resistance circuit. The soft switching condition of the proposed circuit topology will be maintained by the auxiliary circuit. So, the auxiliary circuit will be improved the conversion efficiency and the conduction loss will be reduced. The proposed bidirectional converter topology will be implemented in MATLAB working platform and the output performance will be analyzed.

    Copyright © 2014 Praise Worthy Prize - All rights reserved


    Keywords: Ultra Capacitor, Zero Voltage Switching (ZVS), Zero Current Switching (ZCS), PWM DC-DC Converter.


    Design and Realization of Maximum Boost Switched Inductor Z-Source Inverter for Three Phase On-Line UPS

    by K. Chitra, A. Jeevanandham, Nimitha Ashok


    Abstract - This paper proposes switched inductor Z-source inverter (SL-ZSI) for three phase on-line UPS with high voltage boost ability. The maximum boost control is attained using third harmonic injection. The proposed inverter employs a unique impedance network to couple the main circuit and the power source. SL-ZSI adds two inductors and six diodes to enlarge voltage adjustability. To obtain a high voltage conversion ratio it needs only a shoot through state. SL-ZSI concept can be applied to all dc- to –ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion. The proposed method is simulated using MATLAB/Simulink and the result satisfies the theoretical analysis.

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    Keywords: Boost Factor, Maximum Boost PWM, Switched Inductor ZSI, ZSI, On-Line UPS.


    Three-Phase Shunt Active Filter with Compensation of ReactivePower

    by A. Ouchatti, A. Abbou, M. Akherraz, A. Taouni


    Abstract - This paper presents an adaptive control of a three-phase voltage converter used as active filter to eliminate the harmonic currents absorbed by non-linear loads. After modeling the system (converter - interconnection inductanceto the electrical network - DC bus capacitor), the controller design is based on application of Lyapunovfunctionstability. The main objective of the control is to ensure the compensation of harmonic currents and reactive power. The secondary objective is to regulate the DC bus voltage. The controller discussed in this work is an adaptive version that takes into account variations of losses in the power switches and the losses in the interconnection inductance with network. Results of simulation are presented to illustrate the performances of the proposed command.

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    Keywords: Shunt Active Filter, Instantaneous Power Theory, Lyapunov Function, Nonlinear Loads, Total Harmonic Distortion THD.


    A Comparative Study of Modular Axial Flux Podded Generators for Marine Current Turbines

    by Sofiane Djebarri, Mohamed Benbouzid, Jean Frédéric Charpentier, Franck Scuiller


    Abstract - This research note deals with performance comparison of axial flux modular podded generators for marine current turbines (MCTs). Due to the submarine environment, maintenance operations are very hard, very costly, and strongly depending on sea conditions. In this context, the drive train reliability is a key feature for MCTs. For that purpose, a comparative study is proposed, to assess modular axial flux permanent magnet (AFPM) machines potential for reliability improvement. Thereby, designs of direct-drive modular AFPM generator for a given experimental MCT are performed. The proposed study shows that even number sizing of spatially shifted AFPM machine modules leads to the elimination of the electromagnetic torque ripples transmitted to the MCT shaft. Moreover, it is shown that the proposed module-based generator configuration achieves better thermal behavior. As the actives parts masses and costs are expected to be higher, compromises should be carried-out in terms of reliability and fault-tolerance.

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    Keywords: Marine Current Turbine, Axial Flux Permanent Magnet Generator, Design, Optimization.


    A New Sensorless Control Design of Induction Motor Based on Backstepping Sliding Mode Approach

    by A. Bennassar, A. Abbou, M. Akherraz, M. Barara


    Abstract - In this paper, we propose a new sensorless control of induction motor (IM). The design of this control is based on backstepping and sliding mode approaches. First, the backstepping control is designed to steer the flux and speed variables to theirs references and to compensate the uncertainties trough appropriate Lyapunov functions. Second, sliding mode controllers (SMC) is used for stator currents control. Finally, we estimate the rotor speed by using the Luenberger observer (LO) and the rotor flux by using the extended Kalman filter (EKF). Simulation results are illustrated and prove the effectiveness of the proposed sensorless control in different working of speed references and against load torque disturbance.

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    Keywords: Sensorless Control, Backstepping Control, Sliding Mode Control, Induction Motor, Luenberger Observer, Extended Kalman Filter.


    Development of Fuzzy Logic Controller for DC-DC Converter in Electric Vehicle

    by Mardhiah Saripudin, Muhamad Mansor


    Abstract - This paper presents a power converter for an electric vehicle (EV) as a battery charger. An isolated DC-DC converter topology is used in order to convert the high voltage in the main battery (96V), to low voltage (12V) which is an auxiliary battery for use to power up standard accessories in EV. Many topologies have been proposed for such applications. In this paper, an isolated current-fed full bridge buck converter with a combination of fuzzy logic controller (FLC) and PWM voltage mode controller is proposed. Being free of complex equations and heavy computations, the controller is expected to control converters that operate at high frequencies. Finally, the converter circuit is simulated in MATLAB/Simulink to verify the performance of the closed-loop control of the power converter in respect of start-up transient, load regulation, reference voltage, Vref variation and line regulation.

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    Keywords: Electric Vehicle, Full Bridge Buck Converter, Fuzzy Logic Controller.


    Models for Evaluating Energy Savings Achieved by Energy Storage System in Urban Railway

    by Sung-Dae Kim, Kyu-Hyoung Choi


    Abstract - Energy storage systems (ESSs) that reuse the braking energy of trains have been installed in Korean urban railway systems, but the energy savings achieved by the ESSs vary among the systems: Urban railway systems operating with a longer train headway show greater ESS energy savings. This paper proposes a simulation-based approach to evaluate the ESS energy savings, providing the simulation model of an ESS, a DC feeding system of urban railway, and train power that fluctuates continuously while the train travels from station to station. In a simulated case study of an ESS in an urban railway system, the ESS energy savings rate increases from 6.2 % to 13.4 % when the train headway increases from 2.5 min to 7 min. These results indicate that the ESS energy savings increase in direct proportion to the train headway, thus the effect of train headway on the ESS energy savings should be considered when an ESS is introduced in an urban railway system. The proposed simulation-based approach can be applied to a feasibility study of ESS applications to urban railway systems.

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    Keywords: Energy Storage System (ESS), Urban Railway, Energy Savings Rate, Train Headway.


    Structural Behavior of a Ballasted Small Railway Track Under Static and Dynamic Loadings

    by Waluyo Adi Siswanto, Sam Tsae Yun, Wahyu Mulyo Utomo


    Abstract - The aim of this work is to see the structural behavior of ballasted small rail track system under static moving and dynamic loads. The ballasted rail track system is firstly modeled by solid hexahedral and tetrahedral elements representing the rails, sleepers and the ballast. Three simulations are then conducted in LISA; moving static loading, modal vibration and dynamic loading. Four locations are selected to simulate the moving static loading. The longitudinal displacement of the rails and the ballast can be captured on these four locations. The simulation results show that the ballast displaces more at locations where the sleepers are attached. The fluctuations depend on the moving wheels. The first two vibration modes are the cross swaying of the rails followed by two vertical motions and the fifth mode is the longitudinal motion. The velocity and acceleration responses show similar pattern with that static displacement response. In future research, the results can be used for the optimization of the ballast foundation to improve the stability of the small rail.

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    Keywords: Rail Track, Finite Element Analysis, Ballasted Rail Track.


    Techno-Economic Analysis of a Photovoltaic-Fuel Cell Grid-Connected Hybrid Energy System

    by Malious Sheilla, Chee Wei Tan, Cheng Siong Lim


    Abstract - This paper presents the techno-economic analysis of photovoltaic and fuel cell grid-connected system. The photovoltaic generator is an intermittent sources, thus the integration with fuel cell system is needed to provide continuous supply to the demand. The roles of fuel cell in this hybrid system are act as a backup power for the photovoltaic generation. This paper also described the modelling and simulation process of the proposed hybrid system. The modelling process of the system is divided into two parts which is using MATLAB/Simulink and HOMER software. Each characteristic of the system component is analyzed which include the photovoltaic, fuel cell and also the power conditioning converters. The simulation of various configurations in HOMER software focused on the net present cost, cost of energy, electricity produced and the reduction of CO2 emission. The proposed hybrid system can be an alternative solution to overcome the depletion of conventional fossil fuel and reduce the emission of carbon dioxide to be emitted to the atmosphere and preserve our environment.

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    Keywords: Photovoltaic, Fuel Cell, Hybrid Energy System, Techno-Economic, Cost of Energy.


    Geometrical Approximation of the Overhead Power Line Conductors

    by T. Modrić, S. Vujević, T. Majić


    Abstract - A numerical algorithm for segmentation of overhead power line conductors, which form a catenary, for 3D electric and magnetic power frequency field computation is presented. The overhead power line conductor catenary is approximated by a set of straight thin-wire segments. The segmentation algorithm requires only three input data per power line span conductor - the global coordinates of power line span conductor endpoints and the height of the lowest conductor point. On the basis of the presented theory, a FORTRAN program was developed and results of the overhead power line conductor segmentation with different number of straight segments along the span are compared and graphically presented.

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    Keywords: Electric Field, Magnetic Field, Overhead Power Line Conductors, Catenary, Segmentation, Span.


    Robust Adaptive Backstepping Control for Wind Energy Systems with Uncertain PMSGs

    by F. Grouz, L. Sbita


    Abstract - This paper deals with a robust nonlinear adaptive speed control scheme based on backstepping control strategy for a variable speed wind energy conversion system with uncertain permanent magnet synchronous generator (PMSG). The focal aim of this robust control is to maximize wind energy extraction. First, a nonlinearity compensation method based on the pure input–output feedback linearization controller design, is introduced without any uncertainties of the system parameters. Nevertheless, this method is great sensitive to both parameter uncertainties, and load torque disturbance. To overcome this problem and to achieve the maximum power extraction, parameter adaptation laws and adaptive backstepping control scheme are derived, which permits to compensate both variable-speed PMSG wind turbine parameter uncertainties and load torque disturbance. The simulation results demonstrate the effectiveness and robustness of the proposed adaptive backstepping control scheme.

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    Keywords: Wind Energy Conversion System, PMSG, Adaptive Control, Parameter Uncertainty, Maximum Power Extraction, Backstepping, Robustness.


    Active Disturbance Rejection Control for DFIG Based Wind Farms Under Unbalanced Grid Voltage

    by Ali Boukhriss, Tamou Nasser, Ahmed Essadki, Abdellah Boualloch


    Abstract - This paper presents a method for controlling a doubly fed induction generator used in the conversion of wind power under an unbalanced supply voltage, to eliminate the oscillations, which may occur, due to the presence of negative sequence in the electromagnetic torque and active power delivered to the network. Control strategy based on the voltage oriented control VOC, is used to control the direct and quadrature currents, in both the positive and negative sequence for the network side and rotor side converter. For its robustness to uncertainties that may arise into the physical plant parameters and the needless exact knowledge of physical system, the active disturbance rejection control based on an extended state observer is used to overcome the internal and external uncertainties. Simulations are carried out using Matlab Simulink.

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    Keywords: Active Disturbance Rejection Control, DFIG, Voltage Oriented Control, Extended State Observer, Unbalanced Voltage.


    Fault Detection and Control Loop Reconfiguration for WECS with PMSG Speed Sensor Fault

    by F. Grouz, L. Sbita


    Abstract - This paper describes a fault tolerant controller (FTC) design to enhance the wind energy conversion system (WECS) with Permanent Magnet Synchronous Generator (PMSG) robustness to mechanical rotor speed sensor failure. This proposed sensor FTC strategy is based on the combination of the actual sensor and an adaptive Luenberger observer with a decision-making unit, which detects whether the mechanical sensor is faulty and selects the most accurate generator rotor speed and position for the Indirect Field Oriented control (IFOC) loops. Extensive simulation study shows that the proposed sensor FTC approach can efficiently detect the generator speed sensor fault and tolerate this type of fault, and so offers a simple configuration with a satisfactory accurate reference-rotor-speed tracking requirement for maximum power extraction.

    Copyright © 2014 Praise Worthy Prize - All rights reserved


    Keywords: Wind Energy Conversion System, PMSG, Detection, FTC, Speed Sensor Failure, Adaptive Luenberger Observer, Decision-Making Unit.


    Optimal Load Shedding for Radial Distribution Systems with and without DGs using Particle Swarm Optimization Algorithm

    by Mageshvaran R., Jayabarathi. T., Siva Prasad Reddy S., Leela Rajesh S., Rama Prabha D.


    Abstract - The most important danger for power system security are cascading failures and blackouts during contingency situations. In order to reduce the risk of cascaded outage and blackout, load shedding has been considered as a preventive scheme. This paper presents an application of the heuristic optimization algorithm, particle swarm optimization (PSO) algorithm to find an optimal load shedding strategy for radial distribution systems during an overload contingency. The radial distribution systems are the final link of the interconnection between power systems and the consumers with unidirectional power flows. Overload contingency in the radial distribution systems with and without installed distributed generations (DGs) are the two cases considered in this paper. By the introduction of the distributed generations, the electrical distribution system has a locally looped system and bidirectional power flows. The main objective of the proposed algorithm is to minimize the sum of curtailed load based on their assigned degree of importance and system losses within the operational and security constraints of the system. The proposed method has been tested on 12-bus, 33-bus and 69-bus radial distribution systems. The feasibility of the proposed algorithm has been established and compared with genetic algorithm (GA) in terms of convergence characteristics and solution quality over realistic test systems considered.

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    Keywords: Optimal Load Shedding, Particle Swarm Optimization Algorithm, Distributed Generation.


    A Novel Dissociated Current Control Technique for Harmonic Minimization in Non-Linear Loads

    by T. Parithimar Kalaignan, J. Senthilkumar, Y. Suresh


    Abstract - This paper deals with a novel dissociated current control technique for the power quality enhancement. The hybrid filter has its establishment on harmonic minimization and can be used for nonlinear loads. The reference current extraction is by means of stationary “abc” reference frame and then transformed to orthogonal “dq” transformation. A proportional-integral control system is derived through linearization of nonlinear shunt active filter system model, so that the task of current control dynamics and dc capacitor voltage dynamics become dissociated. The Proportional Integral controllers are used to control the dc bus link voltage and to control the shunt hybrid filter input currents. The currents track closely their references so that the shunt hybrid filter behaves as a quasi-ideal current source connected in parallel with the load. It compensates the reactive power and harmonic currents required by the non linear load, thereby achieving sinusoidal supply currents in phase with supply voltage both dynamic and steady-state conditions. The shunt hybrid filter is implemented with three phase current controlled Voltage Source Inverter for compensating the current harmonics by injecting equal but opposite filter currents. The Shunt hybrid filter is more efficient in harmonic minimization. The proposed shunt hybrid filter maintains the THD threshold as recommended by IEEE-519 standards. This proposed technique is implemented in MATLAB simulink software.

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    Keywords: Harmonic Compensation, Shunt Hybrid Power Filter, Dissociated Current Control.


    A Solution to the Profit Based Unit Commitment Problem Using Integer-Coded Bacterial Foraging Algorithm

    by T. Venkatesan, C. Muniraj


    Abstract - In this paper, the Integer-Coded Bacterial Foraging Algorithm is proposed to solve the Profit Based Unit Commitment problem under deregulated environment. The objective function of Bacterial Foraging Algorithm is formulated to maximize the Generation Companies profit. A Profit Based Unit Commitment problem is one of the most difficult and complex problems for the power sectors under deregulated environment. This work, explains the softer demand constraint to allocate fixed and transitional cost to the scheduled hours. The Integer-Code Bacterial Foraging Algorithm (ICBFA) is on the base of foraging behavior of E-coli Bacteria in the human intestine. This proposed algorithm is simulated using MATLAB software. The IEEE 39 bus10 unit test system with 24 hour data is taken as the input for simulation. It is observed from the simulation results that the proposed algorithm provides maximum profit with less computational time compared to previously reported result.

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    Keywords: Deregulation, Profit Based Unit Commitment (PBUC), Bacterial Foraging Algorithm (BFA).


    A New Approach for Solving Hydrothermal Unit Commitment and Scheduling for Generating Companies Using Particle Swarm Optimization

    by S. Padmini, R. Jegatheesan, Subhransu Sekhar Dash, S. Hemanth


    Abstract - This paper presents a new approach for solving the short-term hydrothermal co-ordination problem for Generating Companies (GENCO) using Particle Swarm Optimization (PSO). In the past the main objective of power utilities was to minimize the total cost of the thermal units taking into account of both thermal and hydro constraints while satisfying the various constraints. However in a restructured power system, the objective is to maximize the profit of GENCO without considering the necessity of satisfying the forecasted demand. This paper presents results on test case of a cascaded chain of four-hydro plants and three-thermal plants. Here, the thermal power to be generated is calculated by subtracting the hydropower available from the load demand for the scheduled time periods. In this paper, an novel method is proposed for solving hydrothermal unit commitment and scheduling problem clubbed together using PSO technique in a competitive electricity market. Unit Commitment (UC) is performed for the three-thermal power plants so that their on/off status can be determined and accordingly optimum schedule can be calculated. A numerical result demonstrates the improved effectiveness of the presented algorithm as compared to the conventional method.

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    Keywords: Hydrothermal Scheduling, Profit Based Unit Commitment (PBUC), Particle Swarm Optimization (PSO), Generating Companies (GENCO).


    Renewable Energy Based Shunt Compensator for Power Quality Improvement Using P-Q Control Theory

    by Aravindan P., Sanavullah M. Y., Vijayakumar G.


    Abstract - This paper presents an operation of Photo-voltaic (PV) system based Shunt Active Filter (PV-SAF) for harmonic mitigation and reactive power compensation. When the PV system generates excessive or equal power required to the load demand, then the coordinating logic disconnecting the service grid from the load and reduce of panel tariff and global warming gasses. The PV module is connected to the DC side of SAF through the DC-DC converter with fuzzy based Perturb & Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm to eliminate the drawback of the conventional PV system. The reference currents extract by the Fuzzy logic controller based PQ control strategy. This proposed PV-SAF, if connected at the terminals of a small industry or a home or a small enlightening institution can avoid the use of interruptible power supply and individual stabilizer. A MATLAB simulink is presented to validate the advantage of the proposed system.

    Copyright © 2014 Praise Worthy Prize - All rights reserved


    Keywords: Shunt Active Filter (PV-SAF), P&O MPPT, DC-DC Converter, Energy Conservation.


    Design of Super-Capacitor based Frequency Control Ancillary Services with the Computation of Ancillary Service Requirement Assessment Indices

    by N. D. Sridhar, I. A. Chidambaram


    Abstract - The successful operation of an interconnected power system requires not only matching the total generation with total load and the associated system losses but also should emphasis better Ancillary Services for improved power quality. The disturbances to the power system due to a small load change can even result in wide deviation in system frequency and quick restoration process are of prime importance not only based on the time of restoration and also should ensure stability limits. This paper proposes various design procedures for computing Power System Ancillary Service Requirement Assessment Indices (PSASRAI) for a Two-Area Thermal Reheat Interconnected Power System (TATRIPS) in a restructured environment based on the settling time and peak over shoot concept of the control input deviations of each area. Energy storage is an attractive option to augment demand side management implementation, so Super Capacitor Energy Storage (SCES) unit can be efficiently utilized to meet the demands. The design of the Proportional plus Integral (PI) controller gains for the restructured power system without and with SCES unit are carried out using Bacterial Foraging Optimization (BFO) algorithm. These controllers are implemented to achieve a faster restoration time in the output responses of the system when the system experiences with various step load perturbations. In this paper the PSASRAI are calculated for different types of possible transactions and the necessary remedial measures to be adopted are also suggested.

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    Keywords: Bacterial Foraging Optimization, Load-Frequency Control, Super Capacitor Energy Storage, Proportional plus Integral Controller, Restructured Power System, Ancillary Service, Power System Ancillary Service Requirement Assessment Indices.


    Firefly Algorithm Based Optimization of Strategic Bidding to Maximize Profit and Benefit of Competitive Electricity Market

    by K. Asokan, R. Ashokkumar


    Abstract - The reconstruction of electric power industry may have significant effect on issues pertaining to economic and reliable operation of electric power system. Generation companies and large consumers are experiencing a different task of designing the proper handling methodologies. Therefore the systematic development of optimal bidding strategy becomes a major concern of Generation companies and power consumers. In this paper an innovative approach for defining optimal bidding strategy is presented as a multi objective stochastic optimization problem and solved by Firefly algorithm (FA). The Firefly Algorithm is a Meta heuristic, nature inspired, optimization algorithm which is based on the social flashing behavior of fireflies and has been introduced for the bidding problem to obtain the global optimal solution. The proposed Firefly algorithm effectively maximizes the GENCOs profit and benefit of large consumers. A numerical example with six suppliers and two large consumers is considered to illustrate the salient features of the proposed method and test results are presented. The simulation result shows that these approaches effectively maximize the Profit and Benefit of Power suppliers and Large Consumers, converge much faster and more reliable when compared with available methods.

    Copyright © 2014 Praise Worthy Prize - All rights reserved


    Keywords: Electricity Market, Optimal Bidding, Profit Maximization, Customer Benefit, Firefly Algorithm.


    Modelling and Simulation of a Variable Step Size Algorithm for a Power Simulator

    by K. Keerthivasan, K. Geetha, V. Sharmila Deve


    Abstract - The Dispatcher Training Simulator (DTS) is used for imparting training in power system operation and allied areas. It facilitates the dispatcher to be trained in normal, emergency and restorative conditions. A numerically stable algorithm that can accommodate larger time step width will be an ideal choice for DTS, but it should also have smaller time step width to capture short term dynamics. Hence, an algorithm has been developed, for simulation of long-term dynamics at a ‘larger time step width’, in order to decrease the total simulation time while the simulation is made to run for a 24 hour system load curve and also to capture the short term dynamics with a ‘small time step width’. To these authors’ knowledge the approach used in this algorithm has not been used elsewhere. This article presents the modelling and simulation of a variable step size algorithm for a DTS. Long-term dynamics gives an observable system response, which can be used to train system operators. Short-term dynamics gives the transient stability of the system. An efficient Network Topology Processor and apt component models were interfaced with this algorithm. This algorithm has been implemented in a DTS - Power System Simulation Module and tested for many possible cases like, Bus fault application and removal, Line opening and closing, etc.

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    Keywords: DTS, Time Step, Simulation, Variable Step Size Algorithm.


    Modelling and Simulation of Interference Cancellation Receiver for MIMO Multicarrier CDMA based Cognitive Radio

    by S. Mohandass, G. Umamaheswari


    Abstract - In this paper, modeling and simulation of a receiver with interference cancellation technique for the downlink transmission of multiple input multiple output (MIMO) multicarrier code-division multiple access (MC-CDMA) based cognitive radio is investigated. Synchronous transmission of multiple users’ signals over frequency selective Rayleigh channel is considered. Linear MMSE frequency domain equalization is utilized to overcome channel effect. Orthogonal Variable Spreading Factor (OVSF) codes are used to support users of different data bit rates. An adaptive subcarrier deactivation method is proposed for deactivating a set of subcarriers used for downlink transmission by the cognitive radio base station that overlap with primary user’s transmission in order to avoid causing interference to the primary user. Orthogonality between the spreading codes is lost due to subcarrier deactivation which causes interference among secondary cognitive radio users. In this paper a modified Group-wise Successive Interference Cancellation (m-GSIC) technique is proposed to suppress the interference caused due to subcarrier deactivation. The simulation results show that the proposed interference cancellation technique results in better BER performance over conventional interference cancellation techniques.

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    Keywords: Multiple Input Multiple Output (MIMO), Multicarrier- Code Division Multiple Access (MC-CDMA), Orthogonal Variable Spreading Factor (OVSF), Adaptive Subcarrier Deactivation, Group-Wise Successive Interference Cancellation.


    Forces of Internal Combustion Heat Engines

    by Florian Ion T. Petrescu, Relly Victoria V. Petrescu


    Abstract - This paper presents an algorithm for setting the dynamic parameters of the classic main mechanism of the internal combustion engines. It shows the distribution of the forces (on the main mechanism of the engine) to the internal combustion heat engines. Dynamic, the velocities can be distributed in the same way as forces. Practically, in the dynamic regimes, the velocities have the same timing as the forces. The method is applied separately for two distinct situations: when the engine is working on a compressor and into the motor system. For the two separate cases, two independent formulas are obtained for the engine dynamic cinematic (forces speeds). Calculations should be made for an engine with a single cylinder. The velocity change in dynamic feels like a variation in the angular speed the engine shaft. It is more difficult to be considered (theoretically) the effect on multi-cylinder engine.

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    Keywords: Forces Distribution, Velocities Distribution, Forces Speeds, Dynamic Regimes, Internal Combustion Heat Engines, Compressor System, Motor System.


    A Semi-Cylindrical Capacitive-Based Differential Sensing System for Water Content In Crude Oil Measurement

    by Maher Assaad, Aslam. M. Zubair, Tong Bon Tang


    Abstract - A capacitive sensor based measuring system for water content in crude oil is presented. The non intrusive capacitive sensor is made of two semi-cylindrical electrodes which are mounted on outside of the glass tube. The tube is filled with sample under test. The capacitive variation is measured by taking advantage of big dielectric permittivity difference of oil and water. The semi-cylindrical capacitive sensor has ability to detect small capacitance variation (pF) and these variations can be converted into voltage by proposed differential interface circuit. The interface circuit is based on differential sensing technique. Such technique allows the removal of unwanted signals (e.g. temperature, background noise and systematic offset) because they affect both sensors in a similar manner. It however will not auto-compensate for the degradation in sensitivity. Hence, increased accuracy and linearity is achieved by differential sensing technique. Both simulation and actual hardware implementation confirmed the proposed system design. The system is experimentally tested for 0-30% water content in oil and achieved resolution of 0.39%.

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    Keywords: Capacitive Sensor, Water Content, Interface Circuit, Crude Oil, Differential Sensing.