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29,905 Article Results

Dynamic Stability Analysis of Generator with Power System Stabilizers Using Matlab Simulink

10.11591/ijeecs.v2.i3.pp501-509
Marizan Sulaiman , Hayfaa Mohammed Hussein , Rosli Omar , Zulhisyam Salleh
 The dynamics in single machine been connected to an infinite power system bus is analyzed in this paper. This analysis requires certain amount of system modeling level. The main components of the system models are excitation system, synchronous machine and the Power System Stabilizer. The Simulink /Matlab are used as the programming tool for analyzing this system performance. Design optimization arobust PSS based on Genetic Algorithm (GA) approach has been improvement. A proper design is required for this Power System Stabilizer (PSS) performance using the Particle Swarm Optimization (PSO) to archieve this. Then the implemented of the model and response of the dynamic system is been analyzed. The designed without PSS showed an unacceptable system response since as shown in the simulation results, system response with PSS proven to have improvements and PSS succeeding in  stabilizing an unstable system. Therefore this leads to stability of the performance of the generator.
Volume: 2
Issue: 3
Page: 501-509
Publish at: 2016-06-01

Improved Indoor Location Systems in a Controlled Environments

10.12928/telkomnika.v14i2.2901
Selcuk; Akdeniz University Helhel , Atalay; Akdeniz University Kocakusak
The precise localization by using Wi-Fi Access Point (AP) has become a very important issue for indoor location based services such as marketing, patient follow up and so on. Present AP localization systems are working on specially designed Wi-Fi units, and their algorithms using radio signal strength (RSS) exhibit (relatively) high errors, so industry looks more precise and fast adaptable methods. A new model considering/eliminating strong RSS levels in addition to close distance error elimination algorithm (CDEEA) combined with median filters has been proposed in order to increase the performance of conventional RSS based location systems. Collecting local signal strengths by means of an ordinary WiFi units present on any laptop as a receiver is followed by the application of CDEEA to eliminate strong RSS levels. Median filter is then applied to those eliminated values, and AP based path loss model is generated, adaptivelly. Finally, the proposed algorithm predicts locations within a maximum mean error of 2.96m for 90% precision level. This achievement with an ordinary wifi units present on any commercial laptop is comparably at very good level in literature.
Volume: 14
Issue: 2
Page: 748-756
Publish at: 2016-06-01

An Optimum Database for Isolated Word in Speech Recognition System

10.12928/telkomnika.v14i2.2353
Syifaun; Department of Electrical Engineering and Information Technology, Universitas Gadjah Mada Department of Library and Information Science, Islamic State University Sunan Kalijaga Yogyakarta Nafisah , Oyas; Deparment of Electrical Engineering and Information Technology, Universitas Gadjah Mada Wahyunggoro , Lukito Edi; Deparment of Electrical Engineering and Information Technology, Universitas Gadjah Mada Nugroho
Speech recognition system (ASR) is a technology that allows computers receive the input using the spoken words. This technology requires sample words in the pattern matching process that is stored in the database. There is no reference as the fundamental theory to develop database in ASR. So, the research of database development to optimize the performance of the system is required.  Mel-scale frequency cepstral coefficients (MFCCs) is used to extract the characteristics of speech signal and backpropagation neural network in quantized vector is used to evaluate likelihood the maximum log values to the nearest pattern in the database.  The results shows the robustness of ASR is optimum using 140 samples of data reference for each word with an average of accuracy is 99.95% and duration process is 27.4 msec.  The investigation also reported the gender doesn’t have significantly influence to the accuracy.  From these results it concluded that the performance of ASR can be increased by optimizing the database.
Volume: 14
Issue: 2
Page: 588-597
Publish at: 2016-06-01

A Systematic Design towards Usability for Novice Designers

10.12928/telkomnika.v14i2.3116
Hoo; Universiti Tunku Abdul Rahman Meei Hao , Azizah; Universiti Kebangsaan Malaysia Jaafar
Dependence on intuitive and experiences would add more complexity in the design process. Novice designers would follow the design of any existing systems without direction. This paper proposed a systematic design approach that provides guidance for novice designers in achieving the targeted usability goal using patterns, and evaluating the prototypes in achieving the determined usability goals. The proposed approach involved the cooperation of experts in providing direction to the novice designers in achieving usability goal in the system design. A collective decision both from users and experts would be gather to give a clear decision of a chosen prototype. Two experiments that followed the proposed approach were conducted with 7 groups or 33 undergraduate students. Ten industry experts, 10 field experts and 29 prospective users were involved in evaluating the appropriate use of the tool to assist them in making decision during comparative prototype evaluation. The result from both experiments concluded the systematic approach could help the novice designers to emphasize usability along the design process. It was observed that the achievement of important goals in their designed prototype could be easily done if pattern selection was provided to the novice designers. The designed tool to assist novice designers has high reliability and high acceptance level of appropriate of use in making decision for the preferred prototype.
Volume: 14
Issue: 2
Page: 715-724
Publish at: 2016-06-01

SC-FDMA LTE Performance Through High Altitude Platforms Communications Channel

10.12928/telkomnika.v14i2.2646
Iskandar; Bandung Institute of Technology Iskandar , D.; Bandung Institute of Technology Hidayat
It is known that HAPS is one of the promising wireless infrastructures in the years to come. HAPS exploit many advantages from cellular satellite system as well as from cellular terrestrial system. Therefore, HAPS is envisaged as a novel technology for communication. This paper aims at evaluating the performance of a pilot-based channel estimation for uplink LTE using SC-FDMA over Ricean HAPS communication channel. Pilot-based channel estimation is used to estimate an uplink channel of LTE users who transmit the data to HAPS as a base transceiver station (BTS). Analysis is performed to determine the effect of users elevation angle with respect to user position inside HAPS coverage, LTE channel bandwidth, modulation type, and the Doppler frequency shift effect. We found that user’s elevation angle contribute major effect to the pilot-based channel estimation of LTE SC-FDMA performance. System capability to overcome fading effect that users with low elevation angle would be needed to increase the performance. In particular to keep an acceptable performance, in this paper we compensate the channel bandwidth, changing modulation type, and limit the Doppler effect through vehicle speed limitation.
Volume: 14
Issue: 2
Page: 515-522
Publish at: 2016-06-01

Improved Energy Aware Cluster based Data Routing Scheme for WSN

10.12928/telkomnika.v14i2.3375
Khalid; Universiti Teknologi Malaysia Haseeb , Kamalrulnizam; Universiti Teknologi Malaysia Abu Bakar , Abdul; Universiti Teknologi Malaysia Hanan Abdullah , Tasneem; Universiti Teknologi Malaysia Darwish , Fasee; Universiti Teknologi Malaysia Ullah , Adnan; Quaid-e-Awam University of Engineering, Science and Technology Ahmed
Wireless sensor network (WSN) consists of several tiny devices that are dispersed randomly for gathering network field. Clustering mechanism divides the WSN into different sub-regions called clusters. Individual cluster is consisting of cluster head (CH) and member nodes. The main research challenges behind clustering mechanism are to optimize network overheads with efficient data delivery. Sensor nodes are operated by batteries and practically it is not feasible to replace them during sensing the environment so energy should be effectively utilized among sensors for improving overall network performance. This research paper presents an improved energy aware cluster based data routing (i-ECBR) scheme, by dividing the network regions into uniform sized square partitions and localized CH election mechanism. In addition, consistent end-to-end data routing is performed for improving data dissemination. Simulation results illustrate that our proposed scheme outperforms than existing work in terms of different performance metrics.
Volume: 14
Issue: 2
Page: 531-537
Publish at: 2016-06-01

Semi-supervised Online Multiple Kernel Learning Algorithm for Big Data

10.12928/telkomnika.v14i2.2751
Ning; Shangluo University Liu , Jianhua; Shangluo University Zhao
In order to improve the performance of machine learning in big data, online multiple kernel learning algorithms are proposed in this paper. First, a supervised online multiple kernel learning algorithm for big data (SOMK_bd) is proposed to reduce the computational workload during kernel modification. In SOMK_bd, the traditional kernel learning algorithm is improved and kernel integration is only carried out in the constructed kernel subset. Next, an unsupervised online multiple kernel learning algorithm for big data (UOMK_bd) is proposed. In UOMK_bd, the traditional kernel learning algorithm is improved to adapt to the online environment and data replacement strategy is used to modify the kernel function in unsupervised manner. Then, a semi-supervised online multiple kernel learning algorithm for big data (SSOMK_bd) is proposed. Based on incremental learning, SSOMK_bd makes full use of the abundant information of large scale incomplete labeled data, and uses SOMK_bd and UOMK_bd to update the current reading data. Finally, experiments are conducted on UCI data set and the results show that the proposed algorithms are effective.
Volume: 14
Issue: 2
Page: 638-646
Publish at: 2016-06-01

Critical Success Factor in Monetizing Blog

10.12928/telkomnika.v14i2.3041
Andika; Bina Nusantara University Rizky , Bens; Bina Nusanatara University Pardamean
Blog usage has transformed from its initial function as a digital diary into a legitimate form of mainstream media. Nowadays any member of the public can generate income from blogging through monetization even though various factors affect the results of this process. Four factors were identified: traffic, search engine optimization (SEO), post frequencies, and media usage. This study examines the level of importance of these factors through practical implementation into blogs then quantitatively determine which factor is critical for the success of blog monetization. An empirical analysis based on thirty samples of blogs were performed to assess the impact of the received income. The finding showed that the revenue for most of the blogs increased after the implementation of critical factors with SEO being the most critical of all the factors.
Volume: 14
Issue: 2
Page: 757-761
Publish at: 2016-06-01

Harmonic Suppression Rectangular Patch Antenna with Circularly Polarized

10.12928/telkomnika.v14i2.2394
Nurzaimah; Universiti Teknikal Malaysia Melaka Zainol , Zahriladha; Universiti Teknikal Malaysia Melaka Zakaria , Maisarah; Universiti Teknikal Malaysia Melaka Abu , Mawarni; Universiti Teknikal Malaysia Melaka Mohamed Yunus
The rectangular patch antenna with proximity coupling at 2.45 GHz is designed and printed on FR-4 substrate with dielectric constant 4.3 and loss tangent 0.019. The overall size of proposed antenna gives 36 % reduction of substrate area as compared to conventional designs. The symmetrical arm of inverted U-stub and U-slot embedded on the transmission feed line suppress harmonic signal effectively at second and third order with minimum reflection coefficients of –0.51 dB and -2.28 dB respectively while circularly polarization was obtained by corner truncated and U-slot on the patch element. The return loss is -23.95 dB at fundamental modes with gain 4.61 dB and axial ratio of 1.48 dB.
Volume: 14
Issue: 2
Page: 471-477
Publish at: 2016-06-01

Measurement and Evaluation of Tx/ Rx Antennas for X-Band Radar System

10.12928/telkomnika.v14i2.3291
Folin; Research Center for Electronic and Telecommunication, Indonesian Institute of Sciences Oktafiani , Yuyu; Research Center for Electronic and Telecommunication, Indonesian Institute of Sciences Wahyu , Yusuf Nur; Research Center for Electronic and Telecommunication, Indonesian Institute of Sciences Wijayanto
This paper presents the performance evaluation of antennas for microwave transmission and reception in X-band radar systems. The transmitter (Tx) and receiver (Rx) antennas are fabricated on microstrip array structures. The antennas are connected to microwave circuits with transmission lines, coaxial cables, and microwave combiners and splitters. The designed antennas in X-band microwave operation for Tx and Rx parts were fabricated identically by 4x64 microstrip patch antennasin an array structure. The fabricated antennas were measured for return loss (S11), VSWR, radiation pattern, and Gain. The detail methods for the measurements are reported and their results are also discussed. The measured antenna gain of ~20dBi, and beam-width of ~20degreecan be obtained using the fabricated antennas at 9.4GHz microwave operation.
Volume: 14
Issue: 2
Page: 555-562
Publish at: 2016-06-01

Property Analysis of Composable Web services

10.12928/telkomnika.v14i2.2732
Wei; Shandong University of Science and Technology, Liu , Lu; Shandong University of Science and Technology, Wang , Yuyue; Shandong University of Science and Technology, Du , Pin; Shandong University of Science & Technology Wang , Chun; Tongji　University Yan
Web services are basic components constructing a flexible business process software. By composing multiple Web services, a complicated business process across organization and departments can be formed. This paper present a formal model of composable Web services: composed service process nets (CSPNs). Properties of Composable Web services are analyzed based on CSPNs. The relation between a CSPN and its corresponding Web service process subnets are discussed. The property analysis methods of CSPNs are come up with. A dynamic property of CSPNs can be determined based on static net structures by means of the proposed methods.
Volume: 14
Issue: 2
Page: 734-740
Publish at: 2016-06-01

A Novel Multifunction Digital Chip Design Based on CMOS Technology

10.12928/telkomnika.v14i2.3675
Zi-Ang; Zhoukou Normal University Zhou , Wen-Bo; Zhoukou Normal University Geng
The realization of an analog-to-digital-conversion chip has great significance in the applications of electronic products. By considering mature time–number digitization, a new multifunction digital chip with a long time delay was designed in this study on the basis of the principle of analog-to-time conversion (ATC) and the realization of long time delay. With additional resistance, capacitance, and transistors, this chip can easily realize ATC, monostable triggers, Schmitt triggers, and multivibrators. The circuit composition of this chip was analyzed, and every module design was introduced. According to the simulation result of Hspice and CSMC 2P2M CMOS (Complementary Metal Oxide Semiconductor) process database, the chip layout (1mm2) design was accomplished by using CSMC 2P2M CMOS technology. Finally, the designed chip was applied in multiproject wafer flow. The flow test demonstrated that this new chip can meet design goal and is applicable to various digital integrated chip designs as an IP (intellectual property) core.
Volume: 14
Issue: 2
Page: 464-470
Publish at: 2016-06-01

Model Predictive Optimization Control Strategy for Three-level AFE Converter

10.12928/telkomnika.v14i2.2755
Xiaoyan; Anhui University of Science and Technology Shi , Longji; Anhui University of Science and Technology Zhu , Shuijuan; Anhui University of Science and Technology Yu
In view of the fact of traditional MPC prediction for three-level AFE converter with numerous switching vectors, time-cost computation and complex control, a simplified model predictive control algorithm is proposed in this paper. The multiple current prediction is transformed into a single virtual reference voltage vector prediction according to the inverse procedure of the model current prediction, and vector distribution method is adopted which can screens out the optimal vector. In the process of rolling optimization, multi-objective control is carried out by adding neutral point potential balance and reducing switching losses and other constraints to the cost function. Also the control delay of the algorithm is compensated. Finally, simulation experiments of three-level AFE converter under steady-state and dynamic conditions are provided. The results have verified correctness and practicability of the strategy.
Volume: 14
Issue: 2
Page: 440-448
Publish at: 2016-06-01

Implementing OLSR and Wireless VoIP as Low-Cost Infrastructure Telephony for Rural Area

10.12928/telkomnika.v14i2.3364
Istas; Sepuluh Nopember Institute of Technology Pratomo , Asriadi; Sepuluh Nopember Institute of Technology N , Achmad; Sepuluh Nopember Institute of Technology Affandi
Communication is one of essential elements in this life, including the people who live at rural areas. However, telecommunications in rural area especially in Indonesia have many constraints like expensive infrastructure, difficult terrain and electrical problem. This led to a lot of areas that uncovered by telecommunication access. In this paper, we proposed a design and architecture of mobile wireless communication based on modified openWRT as a solution for low-cost communication and telephony infrastructure in rural areas. The design combines VoIP over mesh ad-hoc network as a potential solution for cheap calls and use modified embedded device to save electrical resources as a node to connect each other with multi hop transmissions. With this approach, we get many advantages such as high mobility, easy to use, scalable, low-cost implementation, and low power consumption. This paper presents the measurement result of performance to provide access telecommunication in several conditions. In addition, this paper also shows benchmarking results and lifetime of the node that we use in this prototype. The results show that our node can provide telecommunications access in terms of making calls with good quality using wireless LAN. To sum this up, The OpenVoice node is expected to contribute bridging digital divide in rural areas.
Volume: 14
Issue: 2
Page: 563-573
Publish at: 2016-06-01

Analysis of Stemming Influence on Indonesian Tweet Classification

10.12928/telkomnika.v14i2.3113
Ahmad Fathan; Universitas Islam Indonesia Hidayatullah , Chanifah Indah; Universitas Islam Indonesia Ratnasari , Satrio; Universitas Islam Indonesia Wisnugroho
Stemming has been commonly used by some researchers in natural language processing area such as text mining, text classification, and information retrieval. In information retrieval, stemming may help to raise retrieval performance. However, there is an indication that stemming does not hand over significant influence toward the accuracy in text classification. Therefore, this paper analyzes further research about the influence of stemming on tweet classification in Bahasa Indonesia. This work examines about the accuracy result between two conditions by involving stemming and without involving stemming in pre-processing task for tweet classification. The contribution of this research is to find out a better pre-processing task in order to obtain good accuracy in text classification. According to the experiments, it is observed that all accuracy results in tweet classification tend to decrease. Stemming task does not raise the accuracy either using SVM or Naive Bayes algorithm. Therefore, this work summarized that stemming process does not affect significantly towards the accuracy performance.
Volume: 14
Issue: 2
Page: 665-673
Publish at: 2016-06-01
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