|Title: Laboratory Investigation on Hydrophobicity of New Silicon Rubber Insulator under Different Environmental Conditions|
|Author(s): Muhammad Tariq Nazir, Jiang Xingliang, Shakeel Akram|
|Pages: 01-08||Paper ID: 121003-4848-IJECS-IJENS||Published: June, 2012|
Abstract: In order to find out the hydrophobicity loss while soaking in distilled water, hydrophobicity recovery after soaking, hydrophobicity transfer through different contaminations, hydrophobicity loss under icing and hydrophobicity recovery through contaminated iced new silicon rubber surfaces based on hydrophobicity loss, recovery and transference property of silicon rubber, laboratory studies were carried out. The hydrophobic characteristics were studied by STRI hydrophobicity classification guide and measuring the static contact angle along the silicon rubber surface. The experimental results showed that hydrophobicity loss rate is much slower while soaking new SIR in distilled water as compared to recovery at different temperatures. It is found that the new silicon rubber material surface cannot lost its hydrophobicity completely even soaking for eight days at room temperature but, recovered it completely with different rates at different ambient temperature variations. Hydrophobicity transfer rate through pollution layer at different contaminations under different temperatures is also discussed. Therefore, for this purpose hydrophobicity transference through four different contaminations under different temperatures were carried out artificially in laboratory. In the last part of this paper hydrophobicity loss under icing condition and hydrophobicity recovery through icing surfaces under different conditions at different environmental temperatures, humidity and wind speeds are considered.
|Keywords: Silicone rubber, hydrophobicity, static contact angle, pollution, icing|
|Full Text (.pdf) | 2646 KB|
|Title: Digital Simulation of the Generalized Unified Power Flow Controller System with 60-Pulse GTO-Based Voltage Source Converter|
|Author(s): Rakhmad Syafutra Lubis|
|Pages: 09-17||Paper ID: 123403-8484-IJECS-IJENS||Published: June, 2012|
Abstract: The Generalized Unified Power Flow Controller (GUPFC) is a Voltage Source Converter (VSC) based Flexible AC Transmission System (FACTS) controller for shunt and series compensation among the multiline transmission systems of a substation. The paper proposes a full model comprising of 60-pulse Gate Turn-Off thyristor VSC that is constructed becomes the GUPFC in digital simulation system and investigates the dynamic operation of control scheme for shunt and two series VSC for active and reactive power compensation and voltage stabilization of the electric grid network. The complete digital simulation of the shunt VSC operating as a Static Synchronous Compensator (STATCOM) controlling voltage at bus and two series VSC operating as a Static Synchronous Series Capacitor (SSSC) controlling injected voltage, while keeping injected voltage in quadrature with current within the power system is performed in the MATLAB/Simulink environment using the Power System Blockset (PSB). The GUPFC, control system scheme and the electric grid network are modeled by specific electric blocks from the power system block set. The controllers for the shunt VSC and two series VSCs are presented in this paper based on the decoupled current control strategy. The performance of GUPFC scheme connected to the 500-kV grid is evaluated. The proposed GUPFC controller scheme is fully validated by digital simulation.
|Keywords: 60-pulse GTO thyristor model VSC, UPFC, GUPFC, active and reactive compensation, voltage stability|
|Full Text (.pdf) | 248 KB|
|Title: Mobility Prediction Using Pattern Matching|
|Author(s): Mohammad Al-Hattab, Maen Takruri and Johnson Agbinya|
|Pages: 18-24||Paper ID: 125003-4848-IJECS-IJENS||Published: June, 2012|
Abstract: Real time applications impose strict timing constraints on the delivery of data. To fulfill this requirement in mobile ad hoc networks in which the topology changes frequently, these changes should not affect the Quality of Service (QoS) for data delivery and route updates. The prediction of the mobility of nodes in mobile ad hoc networks becomes a key solution for the delivery of data in real time applications; it enables the reconstruction of the routes just prior to the change of the topology which ensures a smooth and efficient data delivery that satisfies the real time constraints. In this paper we present a mobility prediction scheme for mobile ad hoc networks using the past movements of the nodes and correlation analysis. Real data was simulated using MatLab to validate the proposed scheme.
|Keywords: Cross correlation, pattern matching, topology prediction|
|Full Text (.pdf) | 124 KB|
|Title: Effect Of The Interleaver Types On The Performance Of The Parallel Concatenation Convolutional Codes|
|Author(s): Yahya Jasim Harbi|
|Pages: 25-31||Paper ID: 128703-5858-IJECS-IJENS||Published: June, 2012|
Abstract: In this paper, we study the performance of turbo codes with different types of interleaver. Various issues related to the code performance are investigated. These include the effect of the interleaver length, the interaction between the interleaver and the number of decoding iterations, and the effect of interchanging the interleaver between input and output. Simulation results show that some types of the interleavers can be very competitive to random interleaver for different frame lengths.
|Keywords: Interleavers, PCCCs, Frame size, Iterative decoding, Bit error rate|
|Full Text (.pdf) | 110 KB|
|Title: Behavior of DFIG Wind Turbines with Crowbar Protection under Short Circuit|
|Author(s): Omar Noureldeen|
|Pages: 32-37||Paper ID: 129103-6868-IJECS-IJENS||Published: June, 2012|
Abstract: Doubly Fed Induction Generators DFIG are nowadays widely used in variable speed wind power plants. The dynamic interaction between variable speed DFIG wind turbines and the power system which is subjected to disturbances, such as short circuit faults, is an important issue. The ability of the wind power plant to stay connected to the grid during disturbances is important to avoid a cascading effect due to lack of power. This paper investigates the impact of fault ride through on the stability of DFIG wind turbine using crowbar resistance. Simulation test using MATLAB-Simulink toolbox is implemented on a 9 MW wind farm exports its power to 120 KV grid. The simulation is performed using different crowbar resistances. The variations of rotor current, rotor speed, DC-link voltage, active power and reactive power of the wind farm are investigated.
|Keywords: DFIG, Crowbar Resistance, Rotor Current, Active Power, Reactive Power, Short Circuit|
|Full Text (.pdf) | 426 KB|
|Title: Selection of Suitable Location of the FACTS Devices for Optimal Power Flow|
|Author(s): Rakhmad Syafutra Lubis, Sasongko Pramono Hadi and Tumiran|
|Pages: 38-49||Paper ID: 124703-4848-IJECS-IJENS||Published: June, 2012|
Abstract: The flexible AC transmission system (FACTS) in a power system plays a vital role in improving the power system performance, both the static and dynamic, where improving the stability, reducing the losses and the cost of generation, also enhancing the system loading capability with rerouting the power flow in the network. In order to reach the above goals, these devices must be located optimally. In the proposed work, the sensitivity of system loading factor, corresponding to the real and reactive power balance equations with respect to the control parameters of FACTS, technique plus N-1 contingency criterion with some considerations that fitting with formation of the network are used to consider the location and type of the devices. Furthermore the optimal location and parameter are tested and found with the nonlinear predictor-corrector primal-dual interior-point optimal power flow (OPF) algorithm. The simulation was performed on the IEEE 30-bus, 57-bus and 118-bus power systems for steady-state studies and considering eigenvalue after addition the dynamic component. The optimization results indicate that introduction of FACTS devices in a right location increases the loadability or decreases the losses of the system where the sensitivity of system loading factor and N-1 contingency criterion can be effectively used for the selection of FACTS location.
|Keywords: FACTS, Optimal Power Flow, Interior-Point Method, Sensitivity of system loading factor, N-1 contingency criterion|
|Full Text (.pdf) | 231 KB|
|Title: Space Charge Characteristics of LDPE/MMT Nano-Composite Insulation Material under different Fields and Temperatures|
|Author(s): Shakeel Akram, Liao Ruijin, Muhammad Tariq Nazir, Lijun Yang, Baige|
|Pages: 50-56||Paper ID: 126803-5757-IJECS-IJENS||Published: June, 2012|
Abstract: Low-density polyethylene (LDPE) is one of the types of solid polymers and has been used as insulating material of electrical power cables. When a voltage is applied on LDPE, space charges appear and accumulate. However, the electric field distribution in the sample could be distorted by the accumulation of space charge. The uneven distribution of electric field due to space charge usually results in the electric breakdown of LDPE power cables. Therefore, it is important to understand the mechanism and accumulation of space charges in LDPE power cables and to explore the means of elimination. An improvement in LDPE using Nano-fillers may be one of the ways to overcome this problem. If the Nano-fillers could suppress the accumulation of space charges or improve the migration of space charges in LDPE, the electric breakdown from space charges will be decreased to some extent and due to its high resistivity under high dc stress this material is expected to be used as insulation material in HVDC underground power cables in future. For this purpose a series of measurements with 1% content of MMT and pure LDPE have been taken using PEA technique at different temperatures and electric field. The results showed that temperature, electric field and Nano-filler has great influence on the performance of insulation material.
|Keywords: Space charge, LDPE/MMT Nano-Composite, Pulsed electro-acoustic (PEA), Electric Field, Temperature|
|Full Text (.pdf) | 2207 KB|
|Title: Algorithm for developing Urdu Probabilistic Parser|
|Author(s): Neelam Mukhtar, Mohammad Abid Khan and Fatima Tuz Zuhra|
|Pages: 57-66||Paper ID: 124903-5858-IJECS-IJENS||Published: June, 2012|
Abstract: Any decision error in greedy search procedure results in a wrong parse. Best-first strategy is complicated. The novel algorithm developed in this work is based on multi-path shift reduce-strategy. In this algorithm, if the input matches with more than one clause on the right hand side of a rule in Urdu probabilistic context free grammar the items on the old stack are copied to a new processing stack and subsequently reduce operation is performed. A number of stacks can be created whenever required. The probabilities of the rules can be added for each path. Parse tree with the highest probability is selected as the correct solution. Dry run of the main algorithm shows the superiority of this algorithm over its previous counter parts.
|Keywords: Urdu Parser, Probabilistic Parser|
|Full Text (.pdf) | 95 KB|
|Title: Management of Traffic Accidents Using Web Services|
|Author(s): Fadi F. Fouz, Mohammad O. Afandi|
|Pages: 67-74||Paper ID: 120803-3636-IJECS-IJENS||Published: June, 2012|
Abstract: In this paper, a traffic accident management system based on web services is proposed and developed. Web services are used to integrate a number of subsystems and databases. The subsystems include incidents management system, patrol vehicles tracking system, Google maps API, police data center and accidents reconstruction system. The proposed model of integration is a composition of object, aspect and service orientation paradigms. Although the subsystems have heterogeneity in database, data structures, functions, and resources, the integration based on the proposed model succeeded to pass most of the heterogeneity problems.
|Keywords: Web services, Data integration, Systems Integration, XML|
|Full Text (.pdf) | 613 KB|
|Title: Dynamic Simulation of the Generalized Unified Power Flow Controller in Multi-Machine Power Systems|
|Author(s): Rakhmad Syafutra Lubis, Sasongko Pramono Hadi, Tumiran|
|Pages: 75-84||Paper ID: 124803-3939-IJECS-IJENS||Published: June, 2012|
Abstract: The latest generation of flexible AC transmission system (FACTS) devices, the convertible static compensator (CSC), is the progress of several innovative operating concepts in the historic development and application of FACTS. One of the concepts modelling is the generalized unified power flow controller (GUPFC) have been done, which can control bus voltage and power flows of more than one line or according to even a sub-network. In this paper it derived to pile up a novel nonlinear dynamic simulation of the GUPFC consisting of one shunt converter and two series converters based on voltage source converter (VSCs) and DC link capacitor installed in a substation in a multi-machine power system. The linearised Phillips-Heffron model of the system is introduced with Hammons and Winning model is derived to study oscillation stability. The dynamic simulation of the GUPFC is arranged with a simulation program in Matlab programming language, where the two case study of the four machine twelve bus and three machines fifty seven bus power systems was simulated and presented to investigate the impact of the GUPFC control function on power system oscillation damping and to proof the simulation program reliability. It is found that the basic control function of the GUPFC, the voltage control of the DC link capacitor, interacts negatively with the power system, thus damaging system oscillation stability. In order to counteract the negative interaction measuring is done by either adjusting or equipping the GUPFC with a power oscillation damping (POD), without installing the power system stabilizer (PSS) on each machines are tested. The results demonstrate that a satisfactory damping of power system oscillations can be achieved. It is seen that the GUPFC dynamic simulation can be applied and better than the unified power flow controller (UPFC) for a large scale system as the multi-line control.
|Keywords: FACTS, GUPFC, non-linear dynamic simulation program, linearised Phillips-Heffron model, Hammons and Winning model|
|Full Text (.pdf) | 188 KB|
|Title: Modulation Methods Employed In Digital Communication: An Analysis|
|Author(s): Adeleke, Oluseye A. and Abolade, Robert O.|
|Pages: 85-93||Paper ID: 120403-3838-IJECS-IJENS||Published: June, 2012|
Abstract: The concept of modulation is a key factor in communication, because without an appropriate modulation method or scheme, getting an expected throughput in such a communication effort would be impossible to achieve. Communication engineers and researchers have not relented in trying to find the best modulation methods solution aimed at achieving an expected throughput, bandwidth/power efficiency, low error performance, etc in digital communication networks. Digital modulation is preferred to the analogue modulation due to their error-free capability.Moreso, this choice of digital modulation is dependent on the type of communication network that is to be established. However, trade-offs must be made between the bandwidth efficiency, power efficiency and the cost of implementation of such a network. This paper focuses onsome methods usually employed in the process of modulation in digital communication networks. Specifically, binary phase shift keying, quadrature phase shift keying, eight phase shift keying and sixteen phase shift keying are investigated, using the matrix laboratory (MATLAB) software as the simulation tool in which the bit error rate (BER), symbol error rate (SER), spectral efficiency and power efficiency are comparatively analysed.Findings show that lower end phase shift keying schemes can be used for purposes that involve low error performance and minimum power but low bandwidth efficient while the higher schemes suit purposes that require higher bandwidth efficiency but are low power efficient.
|Keywords: Modulation, Power efficiency, Noise Immunity, Phase Shift Keying, Spectral Efficiency, Bandwidth Efficiency|
|Full Text (.pdf) | 251 KB|