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28,593 Article Results

Development of Compact P-Band Vector Reflectometer

10.11591/.v7i2.pp791-798
Yi Lung Then , Kok Yeow You , Ming Hao Lee , Chia Yew Lee
A compact and low cost portable vector reflectometer is designed for a reliable measurement of reflection coefficient, S11. This reflectometer focuses on return loss measurement of frequency ranges from 450 MHz to 550 MHz. The detection of magnitude and phase is based on the utilization of surface mount Analog Devices AD8302 gain/phase detector. The data acquisition is controlled by using Arduino-Nano 3.0 microcontroller, with the use of two analog to digital converter (ADC) and a digital to analog converter (DAC). One port (Open, short and matched load) calibration technique is used to eliminate systematic errors prior to data acquisition. The evaluation of the reflectometer is done by comparing the result of the measurement to that of vector network analyzer.
Volume: 7
Issue: 2
Page: 791-798
Publish at: 2017-04-01

Fuzzy Recursive Least-Squares Approach in Speech System Identification: A Transformed Domain LPC Model

10.11591/.v7i2.pp842-849
Kah Wai Cheah , Noor Atinah Ahmad
In speech system identification, linear predictive coding (LPC) model is often employed due to its simple yet powerful representation of speech production model. However, the accuracy of LPC model often depends on the number and quality of past speech samples that are fed into the model; and it becomes a problem when past speech samples are not widely available or corrupted by noise. In this paper, fuzzy system is integrated into the LPC model using the recursive least-squares approach, where the fuzzy parameters are used to characterize the given speech samples. This transformed domain LPC model is called the FRLS-LPC model, in which its performance depends on the fuzzy rules and membership functions defined by the user. Based on the simulations, the FRLS-LPC model with this special property is shown to outperform the LPC model. Under the condition of limited past speech samples, simulation result shows that the synthetic speech produced by the FRLS-LPC model is better than those produced by the LPC model in terms of prediction error. Furthermore with corrupted past speech samples, the FRLS-LPC model is able to provide better reconstructed speech while the LPC model is failed to do so.
Volume: 7
Issue: 2
Page: 842-849
Publish at: 2017-04-01

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

10.11591/.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

The Development of an Application Conceived for the Design, Feasibility Study and Data Analysis of Photovoltaic Pumping Systems

10.11591/.v7i2.pp713-719
B. Boukhris , M. Mediouni , L. Elmahni
Because of the rise in diesel and butane prices widely used for pumping, added to their negative impact on both Morocco's environment and trade balance, the use of renewable energies should sound obvious, practical and cost effective. This study offers the transformation of a traditional butane pumping system (BPS) and diesel pumping system (DPS), located on a farm nearby the city of Agadir, into an optimized solar pumping system (SPS). The suggested method is based on a techno-economic study according to the “Business-As-usual” scenario. As a first step, we have dimensioned our pumping system and chosen the elements that constitute it. As a second step, we carried out an economic analysis, based on the calculation of all costs, which makes it possible to ensure the viability of the components of our SPS over its life cycle and brought it to a discounted value. The processing of the different data is made possible thanks to the computer application “PVDesign” which we have developed. This application has allowed us to carry out a comparative study of several techniques of pumping systems. The result of the study is that the SPS beats the other systems at various levels, namely economic, environmental and technical.
Volume: 7
Issue: 2
Page: 713-719
Publish at: 2017-04-01

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

10.11591/.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

Security Measure to Detect and Avoid Flooding Attacks using Multi-Agent System in MANETS

10.11591/.v7i2.pp919-925
Bandana Mahapatra , Srikanta Patnaik
Security is considered as one of the major challenge when it comes to infrastructure less and self dependent network without any centralized control. The vulnerability of Adhoc Network makes it susceptible to external attacks like flooding of hello messages or propagating fake routing messages etc. Such attacks generates a variety of problems like disturbing the network by flooding messages that results in waste of battery which is a vital resource to maintain the life span of the network. Most importantly cause agents to die when unable to reach destination due to fake routing messages causing a heavy loss on part of the nodes generating them to maintain the route knowledge.  The paper proposes a novel technique to identify the flooding attack and measure to overcome them using Multi-Agent system.
Volume: 7
Issue: 2
Page: 919-925
Publish at: 2017-04-01

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

10.11591/.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

Hungarian-Puzzled Text with Dynamic Quadratic Embedding Steganography

10.11591/.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

Modeling and Simulation of VSI Fed Induction Motor Drive in Matlab/Simulink

10.11591/.v7i2.pp584-595
D. Uma , K. Vijayarekha
The theory of reference frames and switching functions are effective in analyzing the performance of the induction motor fed from VSI (Voltage Source Inverter). In this work, mathematical model of Adjustable Speed Drive (ASD) is developed by taking synchronous reference frame equations for induction motor, switching function concept for VSI and non-switching concept for diode bridge rectifier.  The developed model is implemented using MATLAB/Simulink as it is an important tool for the validation of the proposed model. The performance of induction motor is analysed for different frequencies. The developed model is tested for the steady state behavior of machine drive. The proposed mathematical model is validated by the simulation results.
Volume: 7
Issue: 2
Page: 584-595
Publish at: 2017-04-01

Detection of Rogue Access Point in WLAN using Hopfield Neural Network

10.11591/.v7i2.pp1060-1070
Menal Dahiya , Sumeet Gill
The serious issue in the field of wireless communication is the security and how an organization implements the steps against security breach. The major attack on any organization is Man in the Middle attack which is difficult to manage. This attack leads to number of unauthorized access points, called rogue access points which are not detected easily. In this paper, we proposed a Hopfield Neural Network approach for an automatic detection of these rogue access points in wireless networking. Here, we store the passwords of the authentic devices in the weight matrix format and match the patterns at the time of login. Simulation experiment shows that this method is more secure than the traditional one in WLAN.
Volume: 7
Issue: 2
Page: 1060-1070
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/.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

Parallel Genetic Algorithms for University Scheduling Problem

10.11591/.v7i2.pp1096-1102
Artan Berisha , Eliot Bytyçi , Ardeshir Tershnjaku
University scheduling timetabling problem, falls into NP hard problems. Re-searchers have tried with many techniques to find the most suitable and fastest way for solving the problem. With the emergence of multi-core systems, the parallel implementation was considered for finding the solution. Our approaches attempt to combine several techniques in two algorithms: coarse grained algorithm and multi thread tournament algorithm. The results obtained from two algorithms are compared, using an algorithm evaluation function. Considering execution time, the coarse grained algorithm performed twice better than the multi thread algorithm.
Volume: 7
Issue: 2
Page: 1096-1102
Publish at: 2017-04-01

Design of Pervasive Discovery, Service and Control for Smart Home Appliances: An Integration of Raspberry Pi, UPnP Protocols and Xbee

10.11591/.v7i2.pp1012-1022
Sabriansyah Rizqika Akbar , Maystya Tri Handono , Achmad Basuki
Pervasive technology is an important feature in smart home appliances control. With pervasive technology, the user is able to discover and control every device and each service without initialization configuration and setup. Since single-board computer often used in smart home appliances, combining pervasive technology and microcomputer/single-board computer will be important to be applied and make a possibility to create a smart home system based on the requirement of it users that will be beneficial for the smart home users and the developers. This paper proposed a design of pervasive discovery, service, and control system for smart home appliances by integrating Raspberry Pi, UPnP protocols, and Xbee that able to control an RGB LED services such as switching, dimming, change color and read a temperature sensor as an example in smart home appliances. This paper enriched the raspberry Pi GPIO function to be able to control via TCP/IP network with UPnP protocol and receive information from a temperature sensor node via Xbee communication. Service control time is measured with UPnP round trip time by subtracting HTTP response arrival with HTTP request time. GPIO processing time measured at the application level by counting a timer that starts before GPIO process and ended after GPIO successfully executed.
Volume: 7
Issue: 2
Page: 1012-1022
Publish at: 2017-04-01

Compressed Sensing Speech Signal Enhancement Research

10.11591/ijeecs.v6.i1.pp26-35
Kuangfeng Ning , Guojun Qin
The proposed Compressive sensing method is a new alternative method, it is used to eliminate noise from the input signal, and the quality of the speech signal is enhanced with fewer samples, thus it is required for the reconstruction than needed in some of the methods like Nyquist sampling theorem. The basic idea is that the speech signals are sparse in nature, and most of the noise signals are non-sparse in nature, and Compressive Sensing(CS) eliminates the non-sparse components and it reconstructs only the sparse components of the input signal. Experimental results prove that the average segmental SNR (signal to noise ratio) and PESQ (perceptual evaluation of speech quality) scores are better in the compressed domain．
Volume: 6
Issue: 1
Page: 26-35
Publish at: 2017-04-01

The Effect of Plasma-Treated Boron Nitride on Partial Discharge Characteristics of LDPE

10.11591/.v7i2.pp568-575
N.A Awang , M.H Ahmad , Y.Z. Arief , I.H. Zakaria , N.A. Ahmad
Power supply reliability is a key factor in a country economic stability. It is contributed by the reliable power distributor via transmission lines, overhead or underground cables. However, the power cables and accessories are always exposed to pre-breakdown phenomena known as partial discharges (PD) which commonly occur in microvoids, defects or protrusions inside the insulation. To improve the performance of the cable insulation against PD, nanofillers are added into the insulating materials. However, to achieve superior performance of PD resistance, the nanofillers must be homogeneously dispersed into the polymer matrices with tightly bonded interfacial zones. Therefore, this could be achieved by employing method of surface functionalization by using cold atmospheric plasma to strengthen the filler/polymer interfaces. In view of foregoing, this study investigated the effects of surface treated boron nitride (BN) nanoparticles in Low Density Polyethylene (LDPE) on the PD characteristics by following CIGRE Method II at 7 kVrms applied voltage. The phase resolved PD characteristics were performed. The results revealed that by treating the nanofillers with cold plasma, the PD resistance of LDPE were highly achieved compared with the untreated BN nanofillers.
Volume: 7
Issue: 2
Page: 568-575
Publish at: 2017-04-01
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