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28,451 Article Results

A New Compact CPW-Fed Dual-Band Uniplanar Antenna for RFID Applications

10.12928/telkomnika.v16i1.7560
Ahmed El; Hassan 1st University Hamraoui , El Hassane; Hassan 1st University Abdelmounim , Jamal; Hassan 1st University Zbitou , Laarbi; Hassan 1st University Elabdellaoui , Hamid; Moulay Ismail University Bennis , Mohamed; Microwave Group Latrach
In this paper a new dual-band uniplanar monopole antenna fed by Coplanar Waveguide (CPW) line is proposed for Radio Frequency Identification (RFID) applications. The antenna structure includes a CPW fed line and the dual-band operation is achieved from the G-shaped folded antenna. The antenna parameters have been investigated and optimized by using CST Microwave Studio. To validate the CST Microwave Studio results before the antenna achievement, we have conducted another study by using ADS. The final circuit was achieved, measured and validated. Experimental results show that the proposed antenna with compact size of 30*45 mm2 is simple in design and compact in size. It exhibits broadband impedance matching, consistent omnidirectional radiation patterns and appropriate gain characteristics suitable for the microwave RFID applicartions.
Volume: 16
Issue: 1
Page: 102-109
Publish at: 2018-02-01

A Solution to Partial Observability in Extended Kalman Filter Mobile Robot Navigation

10.12928/telkomnika.v16i1.9025
Hamzah; Universiti Malaysia Pahang Ahmad , Nur Aqilah; Universiti Malaysia Pahang Othman , Mohd Syakirin; Universiti Malaysia Pahang Ramli
Partial observability in EKF based mobile robot navigation is investigated in this paper to find a solution that can prevent erroneous estimation. By only considering certain landmarks in an environment, the computational cost in mobile robot can be reduced but with an increase of uncertainties to the system. This is known as suboptimal condition of the system. Fuzzy Logic technique is proposed to ensure that the estimation achieved desired performance even though some of the landmarks were excluded for references. The Fuzzy Logic is applied to the measurement innovation of Kalman Filter to correct the positions of both mobile robot and any observed landmarks during observations. The simulation results shown that the proposed method is capable to secure reliable estimation results even a number of landmarks being excluded from Kalman Filter update process in both Gaussian and non-Gaussian noise conditions.
Volume: 16
Issue: 1
Page: 134-141
Publish at: 2018-02-01

A Survey: Space Vector PWM (SVPWM) in 3φ Voltage Source Inverter (VSI)

10.11591/ijece.v8i1.pp11-18
Shalini Vashishtha , K.R. Rekha
Since last decades, the pulse width modulation (PWM) techniques have been an intensive research subject. Also, different kinds of methodologies have been presented on inverter switching losses, inverter output current/ voltage total harmonic distortion (THD), inverter maximum output of DC bus voltage. The Sinusoidal PWM is generally used to control the inverter output voltage and it helps to maintains drive performance. The recent years have seen digital modulation mechanisms based on theory of space vector i.e. Space vector PWM (SVPWM). The SVPWM mechanism offers the enhanced amplitude modulation indexes (MI) than sinusoidal PWM along with the reduction in the harmonics of inverter output voltage and reduced communication losses. Currently, the digital control mechanisms have got more attention than the analog counterparts, as the performance and reliability of microprocessors has increased. Most of the SVPWM mechanisms are performed by using the analog or digital circuits like microcontrollers and DSPs. From the recent study, analysis gives that use of Field Programmable Gate Arrays (FPGA) can offer more efficient and faster solutions. This paper discusses the numerous existing research aspects of FPGA realization for voltage source inverter (VSI) along with the future line of research.
Volume: 8
Issue: 1
Page: 11-18
Publish at: 2018-02-01

A Real Time Condition Monitoring System for Gears Operating under Variable Load Conditions

10.11591/ijeecs.v9.i2.pp493-501
Abdullah Alwadie
Gears are important component of the rotational power transmission system and are largely used in variable load and speed applications. The faults on the gear generate excessive vibration which leads to breakdown of the machine. Sensor based methods could diagnose gear faults but proved to be expensive and have limited applications due to heavy cost and need of access of gear box for sensor installation.  The motor stator current analysis has been reported to overcome the drawbacks of the sensor based fault detection methods. However, motor stator current analysis has a limited capability for reliable detection of small gear fault signatures typically for low load conditions. This paper presents an alternative non-invasive approach based on instantaneous power analysis of the motor to reliably diagnose gear faults for variable load applications. The theoretical and experimental results indicates that the instantaneous power analysis offers three fault related harmonics and amplitude variations on these harmonics could give the indication of health status of the gear.  The superiority of the proposed instantaneous power analysis technique has been confirmed through experiments performed on three operating points of the motor. The comparison of the amplitude sensitivity of the motor stator current and instantaneous power at three operating points has been performed to validate the superiority of the proposed technique.
Volume: 9
Issue: 2
Page: 493-501
Publish at: 2018-02-01

Designing an Agent for Information Extraction from Persian E-shops

10.12928/telkomnika.v16i1.5943
Nasrin; Islamic Azad University Rasouli , Leila; Islamic Azad University Abedi , Sara; Islamic Azad University Ghaei
E-shops are among the most conventional applications of Electronic Commerce. In these shops, the buyers search for their goods through key words or classifications and read the product description provided by the sellers. Though, when the number of items is high, this gets to be difficult for the users. On the one hand, there are too many e-shops, and browsing in these shops to find the best and most appropriate goods is a difficult and time-consuming process. On the other hand, product descriptions are not the same in different websites, and there are different product forms. This study investigates about products and sellers in various websites based on the conditions and user requirements through software agents which present the extracted information in the form of a table to the users which enables them to compare prices and each seller’s conditions without spending too much time for browsing. Using this method increases precision and recall indices comparing to a conventional user browsing.
Volume: 16
Issue: 1
Page: 455-462
Publish at: 2018-02-01

Efficiency of 128-bit Encryption and Decryption Process in Elgamal Method Using Elliptic Curve Cryptography (ECC)

10.12928/telkomnika.v16i1.6953
Dicky; STMIK Triguna Dharma Nofriansyah , Afzalur; STMIK Triguna Dharma Syaref , Widiarti; STMIK Triguna Dharma R Maya , Ganefri; Universitas Negeri Padang Ganefri , Ridwan; Universitas Negeri Padang Ridwan
Cryptography is a growing science of data security. The integrity of a data is an important thing to keep the secrets contained in the data. In this research will be visualized the efficient quantities that use elliptic curves and do not use them. The Elgamal method is an asymmetric cryptographic algorithm whose complexity of processes. It is especially for digital signatures. This research will discuss about the use of ECC to optimize and streamline the Encryption and Decryption process in particular 128-bit Elgamal method. The hope is that by using elliptic curves the timing of the encryption and decryption process can run faster in the computation of Elgamal Method.
Volume: 16
Issue: 1
Page: 352-360
Publish at: 2018-02-01

Development and Performance Enhancement of MEMS Helix Antenna for THz Applications using 3D HFSS-based Efficient Electromagnetic Optimization

10.12928/telkomnika.v16i1.8000
Abdelhakim; University of Tlemcen Boudkhil , Mohammed; University of Tlemcen Chetloul , Nadia; University of Tlemcen Benabdellah , Nasreddine; University of Tlemcen Benahmed
Interest of Micro-Electromechanical System (MEMS) antennas in Terahertz (THz) applications has rapidly expanded in recent years due to the advent of accurate Computer Aided Design (CAD) tools. The very special needs of newly proposed MEMS antennas, especially with a wide bandwidth range, require advanced optimization procedures of enhancing already established designs. This paper provides a compact design of a wideband MEMS helix antenna optimized using tree-dimensional High Frequency Structure Simulator (3D-HFSS) based on Quasi-Newton (Q-N) and Sequential Non Linear Programming (SNLP) techniques to modify the antenna structure with a high accuracy for the selective band of frequencies by training the samples and minimizing the error from Finite Element Method- (FEM) based simulation tool. The helix antenna is presented using MEMS technology and shows high performance demonstrated by very low return losses of less than -20 to -65 dB for a wide range of frequencies from 2.5 to 5 THz. High antenna geometry precision and efficient performance are finally achieved by rectifying and synthesizing various tunable parameters embedded in silicon substrate including both helix form and feeding line parameters.
Volume: 16
Issue: 1
Page: 210-216
Publish at: 2018-02-01

OFET Preparation by Lithography and Thin Film Depositions Process

10.12928/telkomnika.v16i1.6544
Sujarwata; Universitas Negeri Semarang Sujarwata , Fianti; Universitas Negeri Semarang Fianti , Langlang; Universitas Negeri Semarang Handayani , Aji; Universitas Negeri Semarang Kampus Sekaran Gunungpati Semarang Purwinarko , Susilo; Universitas Negeri Semarang Susilo
The length of the channel OFET based thin film is determined during preparation takes place using the technique of lithography and mask during the metal deposition process. The lithography technique is the basic process steps in the manufacture of semiconductor devices. Lithography is the process of moving geometric shapes mask pattern to a thin film of material that is sensitive to light. The pattern of geometric shapes on a mask has specifications, as follows: long-distance source and drain channels varied, i.e. 100 μm, the width of the source and drain are made permanent. Bottom contact OFET structure has been created using a combination of lithography and thin film deposition processes.
Volume: 16
Issue: 1
Page: 77-83
Publish at: 2018-02-01

Low Complexity Multi-User MIMO Detection for Uplink SCMA System Using Expectation Propagation Algorithm

10.12928/telkomnika.v16i1.7365
Alva; University of Brawijaya Kosasih , Onny; University of Brawijaya Setyawati , Rahmadwati; University of Brawijaya Rahmadwati
Sparse code multiple access (SCMA), which combines the advantages of low density signature (LDS) and code-division multiple access (CDMA), is regarded as one of the promising modulation technique candidate for the next generation of wireless systems. Conventionally, the message passing algorithm (MPA) is used for data detector at the receiver side. However, the MPA-SCMA cannot be implemented in the next generation wireless systems, because of its unacceptable complexity cost. Specifically, the complexity of MPA-SCMA grows exponentially with the number of antennas. Considering the use of high dimensional systems in the next generation of wireless systems, such as massive multi-user MIMO systems, the conventional MPA-SCMA is prohibitive. In this paper, we propose a low complexity detector algorithm named the expectation propagation algorithm (EPA) for SCMA. Mainly, the EPA-SCMA solves the complexity problem of MPA-SCMA and enables the implementation of SCMA in massive MU-MIMO systems. For instance, the EPA-SCMA also enables the implemantation of SCMA in the next generation wireless systems. We further show that the EPA can achieve the optimal detection performance as the numbers of transmit and receive antennas grow. We also demonstrate that a rotation design in SCMA codebook is unnecessary, which is quite rather different from the general assumption
Volume: 16
Issue: 1
Page: 182-188
Publish at: 2018-02-01

Optimal Expenditure and Benefit Cost Based Location, Size and Type of DGs in Microgrids Systems Using Adaptive Real Coded Genetic Algorithm

10.12928/telkomnika.v16i1.6761
Umar; Institut Teknologi Sepuluh Nopember Umar , Firdaus; Institut Teknologi Sepuluh Nopember Firdaus , Adi; Institut Teknologi Sepuluh Nopember Soeprijanto , Ontoseno; Institut Teknologi Sepuluh Nopember Penangsang
The economic issue is an essential element to determine whether DG should be installed or not. This work presents the economical approach for multi-type DGs placement in microgrid systems with more comprehensive overview from DG’s owner perspective. Adaptive Real Coded GA (ARC-GA) with replacement process is developed to determine the location, type, and rating of DGs so as the maximum profit is achieved. The objectives of this paper are maximizing benefit cost and minimizing expenditure cost. All objectives are optimized while maintaining the bus voltage at the acceptable range and the DGs penetration levels are below of the DGs capacities.The proposed method is applied on the 33 bus microgrids systems using conventional and renewable DG technology, namely Photovoltaic (PV), Wind Turbine (WT), Micro Turbine (MT) and Gas Turbine (GT). The simulation results show the effectiveness of the proposed approach.
Volume: 16
Issue: 1
Page: 10-17
Publish at: 2018-02-01

A Multiband Printed Antenna Suitable for Wireless Applications

10.12928/telkomnika.v16i1.7059
S.; University of Hassan 1st Settat El Kilani , L. El; University of Hassan 1st Settat Abdellaouib , J.; University of Hassan 1st Settat Zbitou , J.; CRMEF Terhzaz , A.; University of Hassan 1st Settat Errkik , M.; Microwave Group ESEO Angers Latrach
This study deals with a new research work on a low cost multiband printed antenna which can be used for three operating frequency bands GSM900/PCS/WIFI/Bluetooth. The achieved antenna is mounted on an FR-4 substrate. In this study, the solts technique is used to obtain the multiband behavior. The different solts are inserted in the radiator face and the back face that is the ground. The whole circuit is optimized taking into account the good matching of the input impedance in the operating frequency bands with a stable radiation pattern. In order to optimize the proposed antenna structure we have used CST-MW and to compare the obtained simulation results we have conducted another electromagnetic simulation by using HFSS solver. The final circuit validated into simulation has been fabricated and tested which permits to validate the proposed multiband antenna.
Volume: 16
Issue: 1
Page: 159-165
Publish at: 2018-02-01

A Study of Superconducting Transformer with Short-Circuit Current Limitation

10.11591/ijece.v8i1.pp505-512
V.Z. Manusov , D.A. Pavlyuchenko , J.S. Ahyoev
The paper presents physico-mathematical models for analyzing transient processes in electrical networks having transformers with a high temperature superconducting winding. One of the main purposes of the study is the investigation of the short circuit current limitation process with the use of a transformer with a high temperature superconducting winding, that allows the combination of two series-connected elements, transformer and reactor, in one device. The efficiency of this method for short circuit current limitation is provided by the fact that the critical value of superconducting winding temperature is exceeded under short circuit current flowing, then it passes into the normal state with a high impedance winding, thus limiting a short circuit current. It is important to know the moment when superconducting material passes into the normal state with the loss of superconductivity. For this purpose, the program for calculating the quantity of heat under short circuit current flowing before its interruption was developed. If a 40 MVA transformer with a high temperature superconducting winding is considered, short circuit should be cleared after 100 ms without transformer disconnection. It is proposed to use a hybrid winding in addition to the main winding for short circuit current limitation. Conducted investigations showed that the return of a winding into the superconducting state depends primarily on the ratio between a short circuit current and a rated load current. This represents the criterion for returning or not returning into the superconducting state for transformer windings.
Volume: 8
Issue: 1
Page: 505-512
Publish at: 2018-02-01

Household Purposes in A Single Touch Via Bluetooth Using Smartphones

10.11591/ijeecs.v9.i2.pp351-353
Bhavani Rohit , Rengamani J
Technology emerges in our environment day by day. But, still, we lag in keep on using multiple remotes for every device in our homes. Once Bluetooth came up it changes. People started using mobile phones connected to their devices to hear songs wireless and change channels using a mobile phone. A further implementation is kept on moving with multiple remotes for their usage. So, we had an idea that all our household devices may be controlled on our mobile phones via Bluetooth which is cheaper even for urban peoples. Now, all home devices with remote are IR based which doesn't work on sunlight, fluorescent bulbs due to interference. Switch over Bluetooth control reduces remotes in a sense called plastics. Mobile applications are evolved user-friendly to all the people on the day to day lives. Merge those applications to the household devices to control all household devices operated via remote such as TV, DVD, Home theatres, AC, even Table fan etc., Instead of removing IR's just interface Bluetooth chip on those household devices to control every remote device by using your smartphone. Why I am moving to Bluetooth instead of Wi-Fi. Bluetooth is cheaper, advanced to control devices in the range of 50 meters. But IR is useful to 10 meters, and once you block the signal, it will not work.
Volume: 9
Issue: 2
Page: 351-353
Publish at: 2018-02-01

Modified Discrete Firefly Algorithm Combining Genetic Algorithm for Traveling Salesman Problem

10.12928/telkomnika.v16i1.4752
Ling; Shenyang Normal University Teng , Hang; Shenyang Normal University Li
The Firefly Algorithm (FA) has a few disadvantages in solving the constrained global optimization problem, including that it is difficult to produce initial population, the size of relative attractiveness has nothing to do with the absolute brightness of fireflies, the inertia weight does not take full advantage of the information of objective function, and it cannot better control and constrain the mobile distance of firefly. In this paper, we propose a novel method based on discrete firefly algorithm combining genetic algorithm for traveling salesman problem. We redefine the distance of firefly algorithm by introducing swap operator and swap sequence to avoid algorithm easily falling into local solution and accelerate convergence speed. In addition, we adopt dynamic mechanism based on neighborhood search algorithm. Finally, the comparison experiment results show that the novel algorithm can search perfect solution within a short time, and greatly improve the effectiveness of solving the traveling salesman problem, it also significantly improves computing speed and reduces iteration number.
Volume: 16
Issue: 1
Page: 424-431
Publish at: 2018-02-01

Comparison of Secret Splitting, Secret Sharing and Recursive Threshold Visual Cryptography for Security of Handwritten Images

10.12928/telkomnika.v16i1.6632
Sugianto; Institute of Business Development Indonesia Sugianto , Suharjito; Bina Nusantara University Suharjito , Nico; Bina Nusantara University Surantha
The secret sharing is a method to protect confidentiality and integrity of the secret messages by distributing the message shares into several recipients. The secret message could not be revealed unless the recipients exchange and collect shares to reconstruct the actual message. Even though the attacker obtain shares shadow during the share exchange, it would be impossible for the attacker to understand the correct share. There are few algorithms have been developed for secret sharing, e.g. secret splitting, Asmuth-Bloom secret sharing protocol, visual cryptography, etc. There is an unanswered question in this research about which method provides best level of security and efficiency in securing message. In this paper, we evaluate the performance of three methods, i.e. secret splitting, secret sharing, and recursive threshold visual cryptography for handwritten image security in terms of execution time and mean squared error (MSE) simulation. Simulation results show the secret splitting algorithm produces the shortest time of execution. On the other hand, the MSE simulation result that the three methods can reconstruct the original image very well.
Volume: 16
Issue: 1
Page: 323-333
Publish at: 2018-02-01
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