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29,325 Article Results

Generator Assessment of Hydro Power Station Adequacy after Reconstruction from Classical to HIS SF6 Substation

10.11591/.v7i2.pp729-740
Srete Nikolovski , Goran Slipac , Emir Alibašić
Reliability analysis of substations and generator assessment of power plant stations are very important elements in a design and maintenance process. This paper presents a generator adequacy assessment of a classical “H” scheme for an open conventional substation, which is often used, and a new HIS - High Integrated Switchgear with SF6 gas isolation. Generator adequacy indices of both types of classical and HIS switchgear were compared and the results showed a high level of reliability and availability of the HIS presented substation. The input data were the annual reports of Croatian TSO-Transmission System Operator (HOPS) and statistics of operation events of Croatian National Electricity (HEP Inc.). For the HIS substation, the input reliability data were used from relevant international literature since only few of HIS substations are installed in Croatia. The generator is modelled with a three-state Markov state space model and Monte Carlo simulations were used for the generator assessment analysis. Adequacy indices LOLP and EDNS were obtained using DIgSILENT software.
Volume: 7
Issue: 2
Page: 729-740
Publish at: 2017-04-01

The Weights Detection of Multi-criteria by using Solver

10.11591/.v7i2.pp858-868
Fachrurrazi Fachrurrazi , Yuwaldi Away , Saiful Husin
Multi criteria, which are generally used for decision analysis, have certain characteristics that relate to the purpose of the decision. Multi criteria have complex structures and have different weights depending upon the consideration of assessors and the purpose of the decision also. Expert’s judgment will be used to detect the criteria weights that applied by assessors. The aim of this study is a model to detect the criteria weights and biases on the subcontractor selection and detecting the significant weights, as decisive criteria. A method, which is used to modeling the weights detection, is the Solver Application. Data, totaling 40 sets, has been collected that consist of the assessor’s assessment and the expert’s judgment. The result is a pattern of weights and biases detection. The proposed model have been able to detect of 20 criteria weights and biases, that consist of 4 criteria in  the total weights of 60% (as decisive criteria) and 16 criteria in the total weights of 40%. A model has been built by training process performed by the Solver, which the result for MSE training is 9.73711e-08 and for MSE validation is 0.00900528. Novelty in the study is a model to detect pattern of weights criteria and biases on subcontractor selection by transferring the expert's judgment using Solver Application.
Volume: 7
Issue: 2
Page: 858-868
Publish at: 2017-04-01

Maximum Power Point Tracking using Particle Swarm Optimization Algorithm for Hybrid Wind-Tidal Harvesting System on the South Coast of Java

10.11591/ijece.v7i2.pp659-666
Fransisco Danang Wijaya , Kukuh Daud Pribadi , Sarjiya Sarjiya
This paper proposes a hybrid wind-tidal harvesting system (HWTHS). To extract maximum power from the wind and tidal, HWTHS implements particle swarm optimization (PSO) algorithm in maximum power point tracking (MPPT) method. The proposed HWTHS had been tested on the range of possible input appropriate to the characteristics of the southern coast of Java. The presented result shows that by using PSO-based MPPT algorithm, maximum power point can be achieved. Thus the efficiency of HWTHS is 92 %, 94 % in wind section and 91 % in tidal section. By using PSO-based MPPT, HWTHS can respond well to changes in wind and tidal speed, whether it's a change from low speed to a higher speed or change from high speed to lower speed wherein time to reach new steady state is ± 0.1 s. At varied wind and tidal speed, PSO algorithm can maintain Cp of the system in the range of 0.47 - 0.48 so that power can be extracted to the maximum.
Volume: 7
Issue: 2
Page: 659-666
Publish at: 2017-04-01

Hungarian-Puzzled Text with Dynamic Quadratic Embedding Steganography

10.11591/ijece.v7i2.pp799-809
Ebrahim Alrashed , Suood Suood Alroomi
Least-Significant-Bit (LSB) is one of the popular and frequently used steganography techniques to hide a secret message in a digital medium. Its popularity is due to its simplicity in implementation and ease of use. However, such simplicity comes with vulnerabilities. An embedded secret message using the traditional LSB insertion is easily decodable when the stego image is suspected to be hiding a secret message.  In this paper, we propose a novel secure and high quality LSB embedding technique. The security of the embedded payload is employed through introducing a novel quadratic embedding sequence. The embedding technique is also text dependent and has non-bounded inputs, making the possibilities of decoding infinite. Due to the exponential growth of and quadratic embedding, a novel cyclic technique is also introduced for the sequence that goes beyond the limits of the cover medium. The proposed method also aims to reduce the noise arising from embedding the secret message by reducing bits changed. This is done by partitioning the cover medium and the secret message into N partitions and artificially creating an assignment problem based on bit change criteria. The assignment problem will be solved using the Hungarian algorithm that will puzzle the secret message partition for an overall least bit change.
Volume: 7
Issue: 2
Page: 799-809
Publish at: 2017-04-01

A Tunable Ferrofluid-based Polydimethylsiloxane (PDMS) Microchannel Inductor for Ultra High Frequency Applications

10.11591/ijece.v7i2.pp926-932
Ahmad Hafiz Mohamad Razy , Mohd Tafir Mustaffa , Asrulnizam Abd Manaf , Norlaili Mohd Noh
In this work, a tunable ferrofluid-based polydimethylsiloxane (PDMS) microchannel inductor with high quality factor and high tuning range is proposed. For this project, PDMS is used to create a microchannel with a width and height of 0.53 mm and 0.2 mm respectively. The microchannel is then used to cover the whole design of a solenoid inductor. A solenoid inductor is designed using wire bonding technique where lines of copper and bond wires are used to form a solenoid winding on top of silicon substrate. A light hydrocarbon based ferrofluid EMG 901 660 mT with high permeability of 5.4 is used. The ferrofluid-based liquid is injected into the channel to enhance the performance of a quality factor. A 3D full-wave electromagnetic fields tool, ANSYS HFSS is used in this work to simulate the solenoid inductor. The results obtained in this work gives a quality factor of more than 10 at a frequency range of 300 MHz to 3.3 GHz (Ultra High Frequency range). The highest quality factor is 37 which occurs at a frequency of 1.5 GHz, provides a high tuning range of 112%.
Volume: 7
Issue: 2
Page: 926-932
Publish at: 2017-04-01

Implementation of PWM Control of DC Split Converter Fed Switched Reluctance Motor Drive

10.11591/ijece.v7i2.pp604-609
P. Srinivas
The phase winding of Switched Reluctance Motor is excited during the positive increasing region of the phase inductance to get the motoring action. This is performed through a converter. This paper presents the speed control of DC Split converter fed 4 phase 8/6 Switched Reluctance Motor drive using PWM controller. The speed of the motor is controlled by varying the duty ratio of the PWM controller.  Simulation results are verified with hardware implementation of the controller. The Hall sensors provided in the motor provide signals corresponding to the position of the rotor. The pulses to the IGBT switches are generated by TMS320F2407A DSP controller. The waveforms of the PWM signals and Hall sensor signals are captured by means of Digital Storage Oscilloscope. Motor phase currents, phase voltages and associated numerical values are captured and analyzed by Power Analyzer. Steady state analysis of the drive has been carried out. 
Volume: 7
Issue: 2
Page: 604-609
Publish at: 2017-04-01

Fabrication and Analysis of Amorphous Silicon TFT

10.11591/ijece.v7i2.pp754-758
Srikanth G , Yadhuraj S R , Subramanyam T K , Satheesh Babu Gandla , Uma B V
The display technology and large area electronics got momentum with the introduction of TFT devices. TFTs can be made using different semiconducting materials or organic conducting materials as the active layer. Each one of them differ in their performance depending on the material used for the active layer. In this paper, fabrication of amorphous silicon TFT using PECVD is carried out. Simulation of the a-Si: H TFT is also carried out with the dimensions similar to that of the masks used for the fabrication. The Id-Vd plot for both the simulation and fabrication is obtained and studied.
Volume: 7
Issue: 2
Page: 754-758
Publish at: 2017-04-01

Lyot-based Multi-wavelength Fiber Laser

10.11591/.v7i2.pp981-985
Suhairie Saleh , N. A. Cholan , A. H. Sulaiman , M. A. Mahdi
A multi-wavelength fiber laser which is based on a Lyot filter is experimentally demonstrated. A combination of four-wave mixing in a highly nonlinear fiber and Lyot filter mechanism in the laser cavity is able to generate multi-wavelength with relatively high extinction ratio (ER). At the input current of 100mA, six laser lines with ER more than 5 dB are successfully generated. The wavelength spacing for the multi-wavelength is 0.15nm, corresponding to the characteristics of the Lyot filter used.
Volume: 7
Issue: 2
Page: 981-985
Publish at: 2017-04-01

Wideband Branch Line Coupler with Open Circuit Coupled Lines

10.11591/ijece.v7i2.pp888-893
Muataz Watheq Sabri , N A Murad , M K A Rahim
This paper focuses on the design of a Wideband Branch Line Coupler by using open circuits coupled lines technique. The design is implemented by adding four open circuits coupled lines to the structure of the Conventional Branch Line Coupler. The proposed design of Wideband Branch Line Coupler is simulated using CST microwave software. The simulation results show that the coupler is operated at 3.8 GHz with coupling factor of -3dB and 90̊ phase difference between the two output ports. The prototype is fabricated and measured to validate the simulated results. A similar Wide Bandwidth is observed on simulation and measurement. The structure achieved a fractional bandwidth of 42.63%, and return loss of 21 dB compared to the Conventional Branch Line Coupler (BLC).
Volume: 7
Issue: 2
Page: 888-893
Publish at: 2017-04-01

Implementation of Algorithm for Vehicle Anti-Collision Alert System in FPGA

10.11591/.v7i2.pp775-783
Aiman Zakwan Jidin , Lim Siau Li , Ahmad Fauzan Kadmin
Vehicle safety has becoming one of the important issues nowadays, due to the fact the number of road accidents, which cause injuries, deaths and also damages, keeps on increasing. One of the main factors which contribute to these accidents are human's lack of awareness and also carelessness. This paper presents the development and implementation of an algorithm to be utilized for vehicle anti-collision alert system, which may be useful to reduce the occurrence of accidents. This algorithm, which is to be deployed with the front sensors of the vehicle, is capable of alerting any occurrence of sudden slowing or static vehicles ahead, by sensing the rate of distance change. Furthermore, it also triggers an alert if the driver is breaching the safe distance from the vehicle ahead. This algorithm has been successfully implemented in Altera DE0 FPGA and its functionality was validated via hardware experimental tests.
Volume: 7
Issue: 2
Page: 775-783
Publish at: 2017-04-01

An Accurate Performance Analysis of Hybrid Efficient and Reliable MAC Protocol in VANET under Non-saturated Conditions

10.11591/ijece.v7i2.pp999-1011
Akram A. Almohammedi , Nor K. Noordin , A. Sali , Fazirulhisyam Hashim , Abdulmalek Al-Hemyari
Vehicular Ad Hoc Networks (VANETs) is a technology supporting two types of applications, safety and service applications with higher and lower priorities respectively. Thereby, Medium Access Control (MAC) protocol is designed to provide reliable and efficient data broadcasting based on prioritization. Different from the IEEE 1609.4 (legacy), HER-MAC protocol is a new multi-channel MAC proposed for VANETs, offering remarkable performance with regards to safety applications transmission. This paper focuses on the analysis of packet delivery ratio of the HER-MAC protocol under non-saturated conditions. 1-D and 2-D Markov chains have been developed for safety and non-safety applications respectively, to evaluate mathematically the performance of HER-MAC protocol. The presented work has taken into account the freezing of the backoff timer for both applications and the backoff stages along with short retry limit for non-safety applications in order to meet the IEEE 802.11p specifications. It highlights that taking these elements into consideration are important in modeling the system, to provide an accurate estimation of the channel access, and guarantees that no packet is served indefinitely. More precise results of the system packet delivery ratio have been yield. The probability of successful transmission and collisions were derived and used to compute the packet delivery ratio. The simulation results validate the analytical results of our models and indicate that the performance of our models outperformed the existing models in terms of the packet delivery ratio under different number of vehicles and contention window.
Volume: 7
Issue: 2
Page: 999-1011
Publish at: 2017-04-01

Improved Timing Estimation Using Iterative Normalization Technique for OFDM Systems

10.11591/.v7i2.pp905-911
Suyoto Suyoto , Iskandar Iskandar , Sugihartono Sugihartono , Adit Kurniawan
Conventional timing estimation schemes based on autocorrelation experience performance degradation in the multipath channel environment with high delay spread. To overcome this problem, we proposed an improvement of the timing estimation for the OFDM system based on statistical change of symmetrical correlator. The new method uses iterative normalization technique to the correlator output before the detection based on statistical change of symmetric correlator is applied. Thus, it increases the detection probability and achieves better performance than previously published methods in the multipath environment. Computer simulation shows that our method is very robust in the fading multipath channel
Volume: 7
Issue: 2
Page: 905-911
Publish at: 2017-04-01

A New Methodology of Hierarchical Image Fusion in Framework for Hyperspectral Image Segmentation

10.11591/ijeecs.v6.i1.pp58-65
B. Raviteja , M. Surendra Prasad Babu , K. Venkata Rao , Jonnadula Harikiran
Hyperspectral imaging system contains stack of images collected from the sensor with different wavelengths representing the same scene on the earth. This paper presents a framework for hyperspectral image segmentation using a clustering algorithm. The framework consists of four stages in segmenting a hyperspectral data set. In the first stage, filtering is done to remove noise in image bands. Second stage consists of dimensionality reduction algorithms, in which the bands that convey less information or redundant data will be removed. In the third stage, the informative bands which are selected in the second stage are merged into a single image using hierarchical fusion technique. In the hierarchical image fusion, the images are grouped such that each group has equal number of images. This methodology leads to group of images having much varied information, thus decreasing the quality of fused image. This paper presents a new methodology of hierarchical image fusion in which similarity metrics are used to create image groups for merging the selected image bands. This single image is segmented using Fuzzy c-means clustering algorithm. The experimental results show that this framework will segment the data set more accurately by combining all the features in the image bands. 
Volume: 6
Issue: 1
Page: 58-65
Publish at: 2017-04-01

Novel 9-Steps Automatic AC Voltage Regulator based on Two Step-down Transformers

10.11591/.v7i2.pp576-583
Hussain Attia
A novel design and simulation results of 9-steps automatic AC voltage regulator based on one step-down transformer is presented in this paper. Avoiding the problem of surge at the AC load during controlling jump steps is done through the proposed design. Accurate and smooth controlling function is achieved as well. Instead of the necessity of increasing the number of taps of the used multi tap transformer for wide controlling range of fluctuated AC  supply voltage, the proposed designed adopts using only two step down transformers with 10 Vrms, and 30 Vrms secondary voltages respectively. Through the controlling of the proposed design of AV voltage regulator, the resultant load voltage is equal the AC supply voltage as well as the suitable voltage step which may one of the following voltages; +40V, +30V, +20V, +10V, 0V, -10V, -20V, -30V, -40V. The electronic design is done Multisim software while the electrical circuit connection of step down transformers and relays contacts that is made by using PSIM software for power circuit design.
Volume: 7
Issue: 2
Page: 576-583
Publish at: 2017-04-01

Fault Identification of In-Service Power Transformer using Depolarization Current Analysis

10.11591/ijece.v7i2.pp559-567
M.A. Talib , N.A. Muhamad , Z.A. Malek , B.T. Phung
Preventive diagnostic testing of in-service power transformers require system outage and expert’s knowledge and experiences in interpreting the measurement results. The chemical oil analysis may cause significant variance to measurement results due to the different practices in oil sampling, storage, handling and transportation. Thus, a cost effective measuring technique by means of a simpler method that is able provide an accurate measurement results is highly required. The extended application of Polarization and Depolarization Current (PDC) measurement for characterization of different faults conditions on in-service power transformer has been presented in this paper. The oil sample from in-service power transformers with normal and 3 different faults type conditions were sampled and tested for Dissolved Gases Analysis (DGA) and PDC measurement. The DGA results was used to confirm type of faults inside the transformer while the PDC pattern of oil with normal, partial discharge, overheating and arcing were correlated to the oil sample conditions. The analysis result shows that depolarization current provides significant information to defferenciate fault types in power transformer. Thus this finding provides a new alternative in identifying incipient faults and such knowledge can be used to avoid catastrophic failures of power transformers.
Volume: 7
Issue: 2
Page: 559-567
Publish at: 2017-04-01
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