Showing papers by "Rajasthan Technical University published in 2015"

Three-Stage Design Analysis and Multicriteria Optimization of a Parallel Ankle Rehabilitation Robot Using Genetic Algorithm

Abstract: This paper describes the design analysis and optimization of a novel 3-degrees of freedom (DOF) wearable parallel robot developed for ankle rehabilitation treatments. To address the challenges arising from the use of a parallel mechanism, flexible actuators, and the constraints imposed by the ankle rehabilitation treatment, a complete robot design analysis is performed. Three design stages of the robot, namely, kinematic design, actuation design, and structural design are identified and investigated, and, in the process, six important performance objectives are identified which are vital to achieve design goals. Initially, the optimization is performed by considering only a single objective. Further analysis revealed that some of these objectives are conflicting, and hence these are required to be simultaneously optimized. To investigate a further improvement in the optimal values of design objectives, a preference-based approach and evolutionary-algorithm-based nondominated sorting algorithm (NSGA II) are adapted to the present design optimization problem. Results from NSGA II are compared with the results obtained from the single objective optimization and preference-based optimization approaches. It is found that NSGA II is able to provide better design solutions and is adequate to optimize all of the objective functions concurrently. Finally, a fuzzy-based ranking method has been devised and implemented in order to select the final design solution from the set of nondominated solutions obtained through NSGA II. The proposed design analysis of parallel robots together with the multiobjective optimization and subsequent fuzzy-based ranking can be generalized with modest efforts for the development of all of the classes of parallel robots.

Review on design and control aspects of ankle rehabilitation robots

Abstract: Ankle rehabilitation robots can play an important role in improving outcomes of the rehabilitation treatment by assisting therapists and patients in number of ways. Consequently, few robot designs have been proposed by researchers which fall under either of the two categories, namely, wearable robots or platform-based robots. This paper presents a review of both kinds of ankle robots along with a brief analysis of their design, actuation and control approaches. While reviewing these designs it was observed that most of them are undesirably inspired by industrial robot designs. Taking note of the design concerns of current ankle robots, few improvements in the ankle robot designs have also been suggested. Conventional position control or force control approaches, being used in the existing ankle robots, have been reviewed. Apparently, opportunities of improvement also exist in the actuation as well as control of ankle robots. Subsequently, a discussion on most recent research in the development of novel actuators and advanced controllers based on appropriate physical and cognitive human-robot interaction has also been included in this review. Implications for Rehabilitation Ankle joint functions are restricted/impaired as a consequence of stroke or injury during sports or otherwise. Robots can help in reinstating functions faster and can also work as tool for recording rehabilitation data useful for further analysis. Evolution of ankle robots with respect to their design and control aspects has been discussed in the present paper and a novel design with futuristic control approach has been proposed.

Genetic algorithm based maximum power tracking in solar power generation

Abstract: This paper presents genetic algorithm (GA) based maximum power point tracking (MPPT) for photovoltaic (PV) array integrated with battery storage unit (BSU) as power generation unit in standalone mode. PV generation depends on solar irradiance, site location and environmental factors like temperature, wind and. Thus output of PV output is fluctuating in nature and the addition of non linear load make the situation more critical. GA based MPPT for PV generation works for local optimal solution. DC/DC and boost converter has been used to obtain rated desired rated voltage. BSU acts as secondary source to ensure uninterrupted power supply. A suitable three phase voltage source inverter (VSI), at point of common coupling (PCC), provides regulated power supply. Boost converters incorporating proportional controller (PI) increases PV voltage up to 400V. Conventionally used perturb and observe (PO) algorithm has been used for comparative study. Controlled pulse width modulated (PWM) switching pulse for converter unit and single section LC filter at output terminal eliminates harmonic components. To exhibit the system compatibility resistive, reactive, asynchronous induction motor and nonlinear load has been switched at different instants for variable solar irradiance and temperature.

Comparison of Weibull parameters computation methods and analytical estimation of wind turbine capacity factor using polynomial power curve model: case study of a wind farm

Abstract: Wind speed probability at a site has to be modeled for evaluating the energy generation potential of a wind farm. Analytical computation of wind turbine capacity factor at the planning stage of a wind farm is very crucial. Thus, the comparison of Weibull parameters estimation methods and computation of wind turbine capacity factor are the focus of this paper. Soda wind farm used in this case study is located in the Jaisalmer district of western Rajasthan in India. Modeling of wind speed probability and power curve of wind turbines installed at Soda site were done for analytically estimating the capacity factor of wind turbine. Estimated capacity factors were then compared with the measured values of wind farm for validation of results. Four numerical methods namely graphical, empirical, modified maximum likelihood, and energy pattern factor were used for month-wise Weibull parameters estimation at hub height of 65 m. Power curve of the wind turbine installed at site was modeled using eighth-degree polynomial. Coefficients of polynomial were calculated from the combined use of linear least square method and QR decomposition using Gram-Schmidt orthogonalization method. Results show that the percentage error in annual capacity factor estimation using Weibull parameters estimated from graphical, empirical, modified maximum likelihood, and energy pattern factor methods were +9.98%, −1.59%, −1.22%, and −1.29%, respectively. Annual capacity factor that was estimated using the Weibull parameters calculated from modified maximum likelihood method matched best with the measured values. Graphical method gave the most erroneous results.

Model order reduction by integral squared error minimization using bat algorithm

Abstract: In this paper, a large order system is reduced by using the bat algorithm to a reduced-order approximant The numerator and denominator coefficients of a desired reduced-order system are optimized based on integral square error minimization as an objective function pertaining to a unit-step as input The efficacy of the proposed method is tested with three test systems to get a corresponding reduced-order system The results are satisfactory in terms of minimum error with the proposed method as compared to Routh-Pade approximation and weighted-sum multiobjective harmony search based reduced models

Fitness based particle swarm optimization

Abstract: Particle swarm optimization (PSO) is a popular population based approach used to solve nonlinear and complex optimization problems. It is simple to implement and swarm based probabilistic algorithm but, it also has drawbacks like it easily falls into local optima and suffers from slow convergence in the later stages. In order to reduce the chance of stagnation, while improving the convergence speed, a new position updating phase is incorporated with PSO, namely fitness based position updating in PSO. The proposed phase is inspired from the onlooker bee phase of Artificial Bee Colony (ABC) algorithm. In the proposed position updating phase, solutions update their positions based on probability which is a function of fitness. This strategy provides more position updating chances to the better solutions in the solution search process. The proposed algorithm is named as fitness based particle swarm optimization (FPSO). To show the efficiency of FPSO, it is compared with standard PSO 2011 and ABC algorithm over 15 well known benchmark problems and three real world engineering optimization problems.

Improvement power system stability using Unified Power Flow Controller based on hybrid Fuzzy Logic-PID tuning In SMIB system

Abstract: The paper presents hybrid fuzzy logic - PID tuning controller for damping low frequency oscillations using Unified Power Flow Controller (UPFC) applied on a single-machine infinite-bus (SMIB) system. The intention of the Fuzzy Logic based UPFC controller is to damp power system oscillations. UPFC controller depend upon amplitude modulation index of shunt converter (exciter) mE. So this index has been considered. System response with Damped-UPFC controller without fuzzy logic and PID-fuzzy logic (using mamdani-type inference) based UPFC controller is compared at various conditions of power system. Relevant models have been developed and simulated in Matlab/Simulink R2013a. The hybrid PID-Fuzzy Logic based UPFC controller is designed by selecting appropriate controller parameters based on the facts of the power system performance. All studies show that the PID-fuzzy logic controller has an excellent capability in damping low frequency oscillations.

Hybrid PI-fuzzy logic controller based DC-DC converter

Abstract: DC-DC converters are used to convert one DC voltage to other. One of the main limitations of these converters is unregulated supply of voltage and current. To overcome these problems there are various control techniques used in combination with these converters. The aims of developing the converters are high efficiency and high gain with fast response. A feedback controller for DC-DC boost converter is designed to obtain constant output voltage. Design equations are derived and it is modeled in MATLAB. Extensive simulation is carried out with linear controller parameters and the results are presented. Fuzzy logic controllers (FLC) and FLC tuned by PI controller have been investigated. The comparative study Results point out that FLC tuned by PI controller is superior to the other control strategies because of fast transient response, minimum steady state error and good disturbance rejection under various variations of the operating conditions. Hence, it achieves the most closely output voltage regulation.

Design of frequency reconfigurable microstrip patch antenna for S-Band and C-Band applications

Abstract: This paper presents a technique of microstrip patch antenna for S-band and C-band applications. In this proposed work the frequency reconfigurable microstrip patch antenna with three slots on the ground is proposed. In this there are two switches (copper strip) are placed on the slot at the ground plane to produce three different frequency bands at 3.06, 3.26 for (S-Band) and 4.27 GHz(C-Band) respectively. The proposed antenna is simulated using FR-4 substrate with permittivity 4.1 and substrate thickness 1.5mm. The simulation of the proposed work is conducted with CST. The simulation result shows good directional radiation pattern and the directivity. The simulation result are indicating that the proposed antenna has good impedance matching at every band.

Design and small signal stability enhancement of power system using interval type-2 fuzzy PSS

Abstract: In this paper the performance analysis of an interval type-2 fuzzy logic controller (IT2 FLC) as a power system stabilizer (PSS) is carried out. The input signals to the controller are considered as speed deviation and acceleration. The application of IT2 FLC as PSS (IT2 FPSS) is considered to improve small signal stability of power system. It is considered for three different benchmark systems such as single-machine infinite-bus (SMIB), two-area four-machine and IEEE ten-machine thirty nine-bus power system. The performance with IT2 FPSS is compared against the performance of the power system without PSS, with conventional PSS (CPSS) and with fuzzy PSS (FPSS). The application of IT2 FPSS is extended to two-area four-machine ten-bus and IEEE New England ten-machine thirty nine-bus power system and speed response comparison is carried out with FPSS. The superiority of performance with IT2 FPSS over type-1 FPSS is validated in terms of ITAE, IAE and ISE.

Wide-area measurements-based out-of-step protection system

Abstract: From time to time a sequence of unexpected and often overlapping contingencies may lead to power system angular instability and even blackouts if not addressed adequately by means of out-of-step protection system. This paper proposes the out-of-step protection system structure, which is based on generation sources electromotive forces vectors angle control. Protection system consists of several, strategically located terminals, exchanging with information in real-time by means of communication network. Protection system structure, principles of operation and implementation problems addressed in the paper, as also IEC 61850 communication standard-based implementation described.

Design and performance analysis of PID based controller for SMIB power system using Firefly algorithm

Abstract: This article presents the design of a proportional, derivative and integral (PID) based controller using a new meta-heuristic Firefly algorithm (FFA) to optimize the parameters. The design of proposed PID controller using FFA is considered with an objective function based on minimization of square of error signal to guarantee the stability of a nonlinear power system for a wide range of conditions. The FFA optimized PID controller (FFA-PID) is applied to the standard single-machine infinite-bus (SMIB) power system model, and the performance were compared with previously established Ant Bee Colony based PID controller (ABC-PID), and Many Optimizing Liaisons based PID controller (MOL-PID). The performance is compared with simulation of the nonlinear power system for eight plant conditions, and superiority is validated using performance indices. Moreover, the superiority of the proposed controller is validated by plot of eigenvalue in left half of s-plane and verified over 231 plants, including very heavy operating conditions.

Black Hole Artificial Bee Colony Algorithm

Abstract: Artificial bee colony (ABC) is an efficient methodology to solve optimization problems. Here, in this article a modified variant of ABC, namely Black Hole ABC algorithm (BHABC) is proposed which is based on the natural space black hole (BH) phenomenon. In BHABC, the implementation of BH gives a high exploration ability while maintaining the original exploitation ability of the ABC algorithm. The suggested algorithm is judged against 12 benchmark test functions and accessed with original ABC and its two modifications, that are Best So Far ABC (BSFABC) and Modified ABC (MABC). The results reveals that BHABC is a competitive variant of ABC.

Three-dimensional analytical modeling of vibration behavior of piezoceramic cylindrical shells

Abstract: Dynamic analysis of piezoelectric continuum is quite complex, because it includes the coupling of electrical and mechanical terms. Complexity further increases with the consideration of three-dimensional model analysis. Implementation of the analytical methods in order to obtain a closed-form solution is a cumbersome task even in the case of a moderately complex model. As an alternative, approximation methods are used to circumvent these difficulties. In the present work, Rayleigh–Ritz method is used to obtain the eigenvectors and the eigenfrequencies for the piezoceramic cylindrical shells. Orthogonal polynomials generated using Gram–Schmidt method are used in the Rayleigh–Ritz method to formulate the eigenvalue problem. The present method has an advantage of being adapted by software with great ease and provides much accurate results, which makes it reasonably useful for analysis of more complex piezoceramic structures. The presented approximation method is validated by comparing the results with the previous works done in similar problem and by the finite element analysis.

UWB-MIMO antenna with enhanced isolation for breast cancer detection

Abstract: A compact low profile UWB-MIMO antenna for breast cancer detection is proposed. Two square patches are used in perpendicular to each other in order to achieve good pattern diversity. Two ground stubs etched on the ground plane enhance isolation and increase impedance bandwidth. Simulation has been carried out using CST Microwave studio. Results show that the UWB-MIMO Antenna has an impedance bandwidth of larger than 3.1-11.57 GHz and very good isolation up to 20 dB, making it a good candidate for microwave imaging.

Synthesis of balanced quaternary reversible logic circuit

Abstract: Binary number system based digital logic design has been in use for long with phenomenal increase in circuit sizes, working with binary logic system is becoming increasingly difficult. Multi-valued logic system reduces the significant amount of design effort. Multi-valued ternary logic under GF (3) and quaternary logic under GF (4) are available in the literature, but circuit design based on these logic systems is very few. As traditional computing devices based on irreversible logic are approaching their limit in terms of heat dissipation, power and speed requirement. Reversible computing is emerging as an alternative technology. Usage of multi-valued logic for irreversible computing is also growing. Ternary and quaternary logic based reversible gate have been proposed recently. Ternary logic based design has further been enhanced using balanced logic levels. But, the same is not available for quaternary logic. In this paper, we propose balanced quaternary logic and synthesis approach, which offers significant advantages in logic design. Small circuits like adder subtractor have also been designed based on that approach. We feel that balanced logic based approach will open a new era in multivalued logic design.

A Reconfigurable Polarized Antenna Using Switchable Slotted Ground Structure

Abstract: In this paper, a novel design of square patch antenna with a switchable polarization sense. The propose structure is reconfigurable patch antenna with polarization states being switched among linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarizations (RHCP). This antenna structure has four L-shaped slots on the ground plane, and the Circular Polarization (CP) radiation can be achieved by current perturbation due to the switchable slotted ground plane. The Polarization sense of the proposed antenna is altered by the current path that is redirected with switchable p-i-n diodes on the ground slots. Since the slots and diodes are not on the patch, these are placed on ground so the influences of the slots and p-i-n diodes on antenna performance are minimized. The proposed antenna has a simple and compact structure and can radiate a LP, RHCP a LHCP wave without altering the main beam direction. The results show that polarization reconfigurable antenna has good switchable radiation performance at 2.8 GHz, which can be used for wireless communication systems.

DC-AC converter for load supply in autonomous wind-hydrogen power system

Abstract: This paper is related to autonomous wind power system with typical power demand of 2 to 5kW. Presented power system is designed for private houses or small farms. In the case of low wind speed the energy is provided by energy storage, in mentioned system for this purpose the hydrogen fuel cell was chosen. The main purpose of this paper is to find optimal solutions for creation and control of DC/AC converter used for load supply in the autonomous power supply system. To make the power system more economically profitable the utilization of the heat of fuel cell cooling system should be accomplished. Various new-trend control methods should be implemented of the single-phase 5-level NPC converter therefore decreasing the size of the output filter compared to the implemented classical PWM method.

Parabolic shape ground plane having T-slots directional UWB antenna for airborne radar system

Abstract: A novel design technique of parabolic shape ground plane directional ultra-wideband (UWB) with circular patch antenna for airborne radar system is being presented here. The feed for the proposed directional ultra-wideband antenna is given by microstrip line and T-slots are inserted diagonally at the corners of parabolic ground plane in order to increase the directivity. The simulation analysis of the antenna is done on software CST Microwave Studio using FR-4 substrate with dielectric constant 4.3. The simulated results have shown a good return loss with respect to −10 dB. The radiation pattern characteristics and surface current distributions of the antenna at different frequencies are also given.

Design of a motor drive system for bidirectional DC power flow control

Abstract: A motor drive system for the purpose of bidirectional DC power flow control has been developed. A laboratory test bench has been setup to determine the dynamic properties of the system and to verify the proposed power flow control principle. Control board prototype has been developed and briefly described. Results of full reference power cycle tests have been summarized.

University impact on power supply economy, reliability and sustainability enhancement decreasing climate changes

Abstract: Research in prior scientific areas carried out by Riga Technical university (RTU), in general, and the Institute of Power Engineering as part of the University is of vital importance not only for the development of industry and national economy but is also a significant part of the education and training of young professionals for the Latvian power system and for engineering, design and construction companies. New challenges in the energy and power engineering field as well as economic and political changes in the Baltic countries have revealed a need for educational program refinement and academics requalification. To perform these changes effectively, proper formation of the research project portfolio as well as bids of the Latvian and European industry have been taken into account. The paper describes the most important achieved scientific and practical results. To solve a wide range of complex tasks and to ensure excellence of scientific research, a virtual research laboratory has been created; a brief description of the laboratory is given in the paper.

Modeling of water utilization in hydroelectric power plants on the Daugava River

Abstract: In this paper the task of modeling water utilization in the hydroelectric power plants on the Daugava River is outlined. Difficulties caused by the complexity of the task are discussed and the necessity to decompose it is considered. Unit commitment proves to be especially important subtask as it introduces several constraints and limitations. A possibility to solve it using dynamic programming approach has been offered and the veracity of the mathematical model of reservoirs has been tested in this paper.

Effect of air density on kite power

Abstract: Many researchers have analyzed and gave mathematical equations for the motion of the kite. Different mathematical models for the estimation of kite power has been made by Lloyd, Houska, Argatov I. et al., Jerome Marchand, Pauli Rautakorpi et al. between 1980 to 2013. However in their models for estimation of power and maximum power from kite, they have considered density as constant and is equal to the density of air at the sea level (density of air equals to 1.225 Kg/m3). In this paper, effect of air density on kites flying at high altitude was considered and calculations were made for the estimation of maximum power with air density at the sea level and the air density at the flying height of the kite. For this purpose data given by Pauli Rautakorpi et al. has been considered for estimation of maximum power of the kite. Results were compared for each of the five models, density being constant and density varying with height of the kite. All the five models are compared each other for maximum power with actual air density.

A new gate for low cost design of all-optical reversible logic circuit

Abstract: Reversible computing offers a possible solution for high performance computing and low power consumption. For hardware implementation of reversible logic, optical computers are emerging as one of the promising alternative. Recently, in the literature, reversible logic gates and combinational circuits have been proposed in optical domain using Semiconductor Optical Amplifier (SOA) based Mach Zehnder interferometer (MZI) switches due to its significant advantages such as high speed, low power, fast switching and ease of fabrication. Optical reversible designs have used ad-hoc approaches and require high cost in terms of MZI switches, Beam Splitters (BS), and Beam Combiners (BC) as well as optical delay. In this work, an optical reversible MNOT gate and all-optical realization of 4×4 Toffoli Gate have been proposed which is used in all-optical realization of optimized reversible combinational circuits. A general design approach to realize all-optical reversible circuits based on MZI switches has been proposed first time in the literature. Optimized all-optical reversible 2×1 multiplexer and full adder circuits have been designed using these proposed gates and design approach. All-optical reversible designs of 4×1 multiplexer, 1×4 Demultiplexer and 3to8 Decoder circuits have also been presented in this work first time in the literature. Our results have shown significant improvements over existing designs in terms of MZI switches, BS, BC and optical delay.

Making data in cloud secure and usable: fully homomorphic encryption with symmetric keys

Abstract: Today, cloud offers unlimited computing capabilities at affordable price. However, securing data in cloud ensuring usability and availability of data presents a challenge. Benefits promised by cloud computing cannot be availed fully until security issues are properly addressed. Homomorphic encryption ensures data security during computation as well. Most of the currently available homomorphic encryption schemes are based on public key cryptosystems causing large overhead. We propose a symmetric key encryption scheme with fully homomorphic evaluation capabilities, applicable even in multiuser environment. We also present a protocol for using the proposed scheme to private data processing in clouds. The proposed scheme requires a key size linearly proportional to security parameter causing computational overhead proportional to security parameter.

Audio watermarking by spreading echo in time domain using pseudo noise gray sequence

Abstract: Digital multimedia technology has shown a significant progress day to day in various fields such as entertainment, computer vision, security etc. hence, the distribution and use of multimedia data is much easier and faster. In such an open environment, it is convenient to get the access to various information sources. In present time, several issues are arising such as information security, information authentication, ownership or copyright protection with multimedia contents. Therefore, watermarking is breakthrough technique for resolving these issues for digital multimedia content like image, audio and video. In this paper, to improve the weak points of conventional echo hiding and overcome the problem of less security, we propose an audio watermarking technique based on pseudo-random gray sequences as a confidential key. To satisfy and maximize both imperceptibility and robustness, proposed audio watermarking algorithm based on pseudo-random gray sequences embed multi bits by spreading echo in time domain. The imperceptibility and the robustness of proposed audio watermarking are tested using various attacks and by listening test.

Analysis of automation and heating processes of 120 1 water boiler which is heated up by central heating boiler equipped with automatic briquettes feeding system — ABFS

Abstract: This paper presents analysis of automation and heating processes of 120 liters water boiler which is heated up by universal central heating boiler "Dacon — FB 36" which is equipped with experimental automatic briquettes feeding system.

Hexa band asymmetrical U-slot microstrip patch antenna for wireless applications

Abstract: A single-layer single-patch six-band U-slot patch antenna, with linear polarization, is proposed to satisfy the impedance bandwidth of WiMAX, WLAN, point to point communication, radar, C- band satellite communication applications. This antenna is made by cutting four asymmetrical U-slots in the patch with DGS and coaxial feed. In the proposed design the impedance bandwidths (|S11|<−10dB) of 1.4%, 5.3%, 1.3%, 3.4%, 4.5% and 7.3% are achieved at central frequencies 3.27 GHz, 3.4 GHz, 3.9 GHz,4.9 GHz, 5.3 GHz and 6.1GHz, with gains of 9dBi, 7.9dBi, 7.5dBi, 6.8dBi, 7.7dBi and 6dBi, respectively. In the proposed antenna design the asymmetry of the U-slot arm provides one more degree of freedom. Proposed antenna is also simple and low cost in fabrication.

Output gating performance overhead elimination for scan test

Abstract: Switching activity is much higher in test mode as compared to normal mode of operation which causes higher power dissipation, and this leads to several reliability issues. Output gating is proposed as a very effective low-power test technique, which is used to eliminate redundant switching activity in the combinational logic of circuit under test (CUT) during the shifting of test vectors in a scan chain. This method reduces the average power significantly, but it introduces performance overhead in normal mode of operation. In this work, a new output gating technique is proposed which eliminates redundant switching activity in combinational logic of CUT during shifting of test vectors without any negative impact on performance as compared to earlier proposed output gating techniques. The proposed design also improves the performance of the scan flop in functional mode with negligible area overhead incurred due to extra transistors. Experimental results show that our design has a more robust performance ove...

Design and optimization of high quality factor MEMS piezoelectric resonator with pseudo electrodes

Abstract: The following work reports design and optimization of a MEMS resonator with some pseudo electrodes. Three, five and seven psuedo electrodes are placed and simulated. It has been observed that five psuedo electrodes structure gives very high quality factor in addition to minimum false modes interference. Simulation is done on COMSOL multiphysics. Furthermore, influence of various piezoelectric materials like AlN, PZT and ZnO were studied proving AlN as superb thin piezoelectric film or electroacoustic material, to have a very high Quality factor. Appropriate piezoelectric material is needed in addition with psuedo electrodes in order to work efficiently for filter and RF applications.