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28,428 Article Results

A Mathematical Approach for Hidden Node Problem in Cognitive Radio Networks

10.12928/telkomnika.v15i3.6897
Felix; Universiti Teknologi Malaysia Ahmadu Bello University, Zaria, Nigeria Obite , Kamaludin; Universiti Teknologi Malaysia Mohammad Yusof , Jafri; Universiti Teknologi Malaysia Din
Cognitive radio (CR) technology has emerged as a realistic solution to the spectrum scarcity problem in present day wireless networks. A major challenge in CR radio networks is the hidden node problem, which is the inability of the CR nodes to detect the primary user. This paper proposes energy detector-based distributed sequential cooperative spectrum sensing over Nakagami-m fading, as a tool to solve the hidden node problem. The derivation of energy detection performance over Nakagami-m fading channel is presented. Since the observation represents a random variable, likelihood ratio test (LRT) is known to be optimal in this type of detection problem. The LRT is implemented using the Neyman-Pearson Criterion (maximizing the probability of detection but at a constraint of false alarm probability). The performance of the proposed method has been evaluated both by numerical analysis and simulations. The effect of cooperation among a group of CR nodes and system parameters such as SNR, detection threshold and number of samples per CR nodes is investigated. Results show improved detection performance by implementing the proposed model.
Volume: 15
Issue: 3
Page: 1127-1136
Publish at: 2017-09-01

Histogram Equalization for Improving Quality of Low-resolution Ultrasonography Images

10.12928/telkomnika.v15i3.5537
Retno; Jenderal Soedirman University Supriyanti , Subkhi; Jenderal Soedirman University Adhi Priyono , Eko; Jenderal Soedirman University Murdyantoro , Haris; Jenderal Soedirman University Budi Widodo
The current development of digital image processing techniques have been very rapid. Application of digital image processing both hardware and software are available with a variety of features as a form of superiority. Medical ultrasonography is one of the results of digital image processing technology. It is a kind of diagnostic imaging technique with ultrasonic that is used to produce images of internal organs and muscles, size, structure, and wound pathology, which makes this technique is useful for checking organ. However the images produced by low resolution ultrasonography device is not fully produce clear information. In this research we use histogram equalization to improve image quality. In this paper we emphasize on the comparison of the two methods in the histogram equalization, namely Enhance Contrast Using Histogram Equalization (ECHE) and Contrast-Limited Adaptive Histogram Equalization (CLAHE). The results showed that CLAHE give the best results, with the parameter value Nbins 256 and Distribution Rayleigh with MSE value 9744.80 and PSNR value 8.284150.
Volume: 15
Issue: 3
Page: 1397–1408
Publish at: 2017-09-01

Integrated Open Loop Resonator Filter Designed with Notch Patch Antenna for Microwave Applications

10.12928/telkomnika.v15i3.7218
D.; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Azra Awang Mat , N.; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Syuhada Hasim , Nurmiza; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Othman , Amira; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Amran , D.; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Norkhairunnisa Abang Zaidel , A.; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering S. Wani Marzuki , Shafrida; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Sahrani , Kismet; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering anak Hong Ping , Rohana; Applied Electromagnetic Research Group Department of Electrical and Electronic Engineering Sapawi
This paper presented the design of integrated open loop resonator bandpass filter with notch type antenna for the use in microwave applications. Chebyshev type filter is selected as the filter characteristics and cascaded design with the antenna to produce a single module, Integrated Filter Antenna (IFA). Special feature of the antenna is the implementation of notch on the patch antenna to improve the efficiency. IFA is then simulated in electromagnetic simulation tool, Agilent Advance Design System (ADS) version 2016 and measured using R&S Vector Network Analyzer. It shows that the proposed IFA produced good measured return loss >-30dB with both vertical and horizontal gain of 9.11dBi and 8.01dBi respectively.
Volume: 15
Issue: 3
Page: 1485-1492
Publish at: 2017-09-01

Regression Modelling for Precipitation Prediction Using Genetic Algorithms

10.12928/telkomnika.v15i3.4028
Asyrofa; Universitas Brawijaya Rahmi , Wayan Firdaus; Universitas Brawijaya Mahmudy
This paper discusses the formation of an appropriate regression model in precipitation prediction. Precipitation prediction has a major influence to multiply the agricultural production of potatoes in Tengger, East Java, Indonesia. Periodically, the precipitation has non-linear patterns. By using a non-linear approach, the prediction of precipitation produces more accurate results. Genetic algorithm (GA) functioning chooses precipitation period which forms the best model. To prevent early convergence, testing the best combination value of crossover rate and mutation rate is done. To test the accuracy of the predicted results are used Root Mean Square Error (RMSE) as a benchmark. Based on the RMSE value of each method on every location, prediction using GA-Non-Linear Regression is better than Fuzzy Tsukamoto for each location. Compared to Generalized Space-Time Autoregressive-Seemingly Unrelated Regression (GSTAR-SUR), precipitation prediction using GA is better. This has been proved that for 3 locations GA is superior and on 1 location, GA has the least value of deviation level.
Volume: 15
Issue: 3
Page: 1290-1300
Publish at: 2017-09-01

Improving Posture Accuracy of Non-Holonomic Mobile Robot System with Variable Universe of Discourse

10.12928/telkomnika.v15i3.6078
Siti; Universitas Sriwijaya Nurmaini , Bambang; Universitas Sriwijaya Tutuko , Kemala; Universitas Sriwijaya Dewi , Velia; Universitas Sriwijaya Yuliza , Tresna; Politeknik Negeri Sriwijaya Dewi
This paper presents a method to decrease imprecision and inaccuracy that have the tendency to influence the posture of non-holonomic mobile by using the adaptive tuning of universe of discourse. As such, the primary objective of the study is to force the posture error of x(t), y(t) and θ(t) towards zero. Hence, for each step of tuning the fuzzy domain, about 20% of imprecision and inaccuracy had been added automatically into the variable universe fuzzy, while the control input was bound via scaling gain. Furthermore, the experimental results showed that the tuning of universe fuzzy parameters could increase the performance of the system from the aspects of response time and error for steady state through better control of inaccuracy. Besides, the domains of universe fuzzy input [-4,4] and output [0,6] exhibited good performance in inching towards zero values as the steady state error was about 1% for x(t) position, 0.02% for y(t) position, and 0.16% for θ(t) orientation, whereas the posture error in the given reference was about 0.0002%.
Volume: 15
Issue: 3
Page: 1265-1279
Publish at: 2017-09-01

Packet Loss Rate Differentiation in slotted Optical Packet Switching OCDM/WDM

10.12928/telkomnika.v15i3.5019
Omar; Universiti Sains Islam Malaysia Najah , Kamaruzzaman; Universiti Sains Islam Malaysia Seman , Khairi; Universiti Sains Islam Malaysia Abdulrahim
We propose a multi-class mechanism for Optical Code Division Multiplexing (OCDM), Wavelength Division Multiplexing (WDM) Optical Packet Switch (OPS) architecture capable of supporting Quality of Service (QoS) transmission. OCDM/WDM has been proposed as a competitive hybrid switching technology to support the next generation optical Internet. This paper addresses performance issues in the slotted OPS networks and proposed four differentiation schemes to support Quality of Service. In addition, we present a comparison between the proposed schemes as well as, a simulation scheduler design which can be suitable for the core switch node in OPS networks. Using software simulations the performance of our algorithm in terms of losing probability, the packet delay, and scalability is evaluated.
Volume: 15
Issue: 3
Page: 1061-1071
Publish at: 2017-09-01

Using SVD and DWT Based Steganography to Enhance the Security of Watermarked Fingerprint Images

10.12928/telkomnika.v15i3.6437
Mandy; Institute of Technology Letterkenny Douglas , Karen; Institute of Technology Letterkenny Bailey , Mark; Institute of Technology Letterkenny Leeney , Kevin; Ulster University Curran
Watermarking is the process of embedding information into a carrier file for the protection of ownership/copyright of digital media, whilst steganography is the art of hiding information. This paper presents, a hybrid steganographic watermarking algorithm based on Discrete Wavelet Transform (DWT) and Singular Value Decomposition (SVD) transforms in order to enhance the security of digital fingerprint images. A facial watermark is embedded into fingerprint image using a method of singular value replacement. First, the DWT is used to decompose the fingerprint image from the spatial domain to the frequency domain and then the facial watermark is embedded in singular values (SV’s) obtained by application of SVD. In addition, the original fingerprint image is not required to extract the watermark. Experimental results provided demonstrate the methods robustness to image degradation and common signal processing attacks, such as histogram and filtering, noise addition, JPEG and JPEG2000 compression with various levels of quality.
Volume: 15
Issue: 3
Page: 1368-1379
Publish at: 2017-09-01

Modeling, Analysis and Comparative of Down Sampling based Clamping SV PWM for Cascaded and Diode Clamped Multilevel Inverter fed Induction Motor Drive

10.11591/ijeecs.v7.i3.pp698-707
Ravikumar Bhukya , P. Satish Kumar
This paper presents investigation and performance analysis of novel down sampling based  clamping SV PWM technique for diode and cascaded Multi-level Invereter fed to Induction motor drive. A novel down sampling based clamping SVPWM has developed by adding triangular off set to sinusoidal fundamental waveform is modified by down sampling the reference wave by order of 10 so this technique is called clamping space vector pulse width modulation techniques such as PD, POD and APOD. so as to shift the lower order harmonics to higher order side. This novel carrier is compared with the offset injected space vector reference waveform to generate the required PWM pulses to the inverter. To analyze the performance of the proposed PWM technique it is implemented on  seven level diode and cascaded Multi-level Inverter using Matlab/Simulink software tool for output line, phase voltage, currents, speed, torque and Total harmonic distortion analysis.
Volume: 7
Issue: 3
Page: 698-707
Publish at: 2017-09-01

Brown’s Weighted Exponential Moving Average Implementation in Forex Forecasting

10.12928/telkomnika.v15i3.5410
Seng; Universitas Multimedia Nusantara Hansun , Subanar; Universitas Gadjah Mada Subanar
In 2016, a time series forecasting technique which combined the weighting factor calculation formula found in weighted moving average with Brown’s double exponential smoothing procedures had been introduced. The technique is known as Brown’s weighted exponential moving average (B-WEMA), as a new variant of double exponential smoothing method which does the exponential filter processes twice. In this research, we will try to implement the new method to forecast some foreign exchange, or known as forex data, including EUR/USD, AUD/USD, GBP/USD, USD/JPY, and EUR/JPY data. The time series data forecasting results using B-WEMA then be compared with other conventional and hybrid moving average methods, such as weighted moving average (WMA), exponential moving average (EMA), and Brown’s double exponential smoothing (B-DES). The comparison results show that B-WEMA has a better accuracy level than other forecasting methods used in this research.
Volume: 15
Issue: 3
Page: 1425–1432
Publish at: 2017-09-01

An Upgraded Transverse Electromagnetic Parallel Plates for Dielectric Measurement

10.12928/telkomnika.v15i3.7213
S.; Universiti Tun Hussein Onn Malaysia K. Yee , R.; Universiti Tun Hussein Onn Malaysia Padu , C.; Universiti Tun Hussein Onn Malaysia K. Sia , X.; Universiti Tun Hussein Onn Malaysia T. I. Ngu , S.; Universiti Tun Hussein Onn Malaysia H. Dahlan , M.; Universiti Tun Hussein Onn Malaysia A. Azlan
A new version of transverse electromagnetic parallel plates with irregular plates’ width and plate separation has been developed for dielectric measurement. The separations between the plates are supported by four rectangular Teflon block and 1 mm of groove is proposed at the center of the upper plate to maintain the measurement repeatability. The groove enables the samples which are slightly higher than 2 cm to be fitted well between the plates without introducing extra force to the plates. Theperformance of both parallel plates has been compared in the frequency range from 100 MHz to 1.1 GHz. It is found that the upgraded parallel plate offers better return loss and insertion loss above 500 MHz compared to the previous parallel plate. It is reported from this work that the return loss of the parallel plate must be lower than -15 dB in order to achieve accurate dielectric constant. However, the insertion loss of the parallel plates does not influence the real permeability significantly. The upgraded TEM parallel plateproduces a consistent reading with a standard deviation of less than 0.05 above frequency 200 MHz. The dielectric measurement of Polypropylene (PP) has proven the capability of this upgraded TEM parallelplate.
Volume: 15
Issue: 3
Page: 1446-1453
Publish at: 2017-09-01

Use of Automation Codecs Streaming Video Applications Based on Cloud Computing

10.12928/telkomnika.v15i3.2810
Hero; Sekolah Tinggi Teknologi Adisutjipto Wintolo , Anggraini; Sekolah Tinggi Teknologi Adisutjipto Kusumaningrum , Handoko Widya; Sekolah Tinggi Teknologi Adisutjipto Kusuma
Streaming technology is currently experiencing a great progress. Faster internet more users streaming. Streaming services that exist today there are still weaknesses in both the upload speed, streaming speed and limited types of video extensions that can be played. To resolve these problems then made a video streaming service based local area network with a system of cloud computing that can work effectively in terms of upload speeds, streaming and variations in video formats. Video streaming application is classified as a service IaaS (Infrastructure as a Service Cloud) in cloud computing. On the use of streaming applications the user does not need to convert the video, with the purpose of uploading process can be faster and applications can play a variety of video formats.
Volume: 15
Issue: 3
Page: 1409–1415
Publish at: 2017-09-01

Wireless Body Area Networks for Healthcare Applications: An Overview

10.12928/telkomnika.v15i3.5793
Muhammad; Universiti Teknologi Malaysia Anwar , Abdul Hanan; Universiti Teknologi Malaysia Abdullah , Kashif Naseer; Bahria University Qureshi , Abdul Hakeem; Universiti Teknologi Malaysia Majid
Healthcare systems have been facing various new challenges due to increasing and rising aging population in healthcare. Advance information and communication technologies have introduced Wireless Body Area Networks (WBANs) for healthcare systems. WBANs provide different monitoring services in healthcare sector for monitoring their patients with more convenience. WBANs are economical solutions and non-invasive technology for healthcare applications. This review paper provides a comprehensive review on WBANs applications, services and recent challenges.
Volume: 15
Issue: 3
Page: 1088-1095
Publish at: 2017-09-01

New Miniature Planar Microstrip Antenna Using DGS for ISM Applications

10.12928/telkomnika.v15i3.6864
R.; University of Hassan 1st Settat Er-rebyiy , J.; University of Hassan 1st Settat Zbitou , M.; Microwave Group ESEO Angers Latrach , A.; University of Hassan 1st Settat Tajmouati , A.; University of Hassan 1st Settat Errkik , L. EL; University of Hassan 1st Settat Abdellaoui
The aim of this paper is to use defected ground structures (DGS) in order to miniaturize a microstrip patch antenna. The DGS structure is integrated in the ground plane to improve the performance of the planar antenna, and shifted the resonance frequency from 5.8 GHz to 2.5 GHz, with a miniaturization up to 83%. The antenna is designed, optimized, and miniaturized by using the CST MW-studio, mounted on an FR-4 substrate having a dielectric constant 4.4, a loss tangent tan (ɸ)=0.025, thickness of 1.6 mm with the whole area of 34X34 mm2.The proposed antenna is suitable for ISM (Industrial, Scientific and Medical) applications at 2.5 GHz with S11 ≤(-10) dB. The antenna is fed by 50ohm input impedance and it has good performances in terms of matching input impedance and radiation pattern. The proposed antenna was fabricated and tested.Simulation and measurement results are in good agreement. 
Volume: 15
Issue: 3
Page: 1149-1154
Publish at: 2017-09-01

Predicting the Presence of Learning Motivation in Electronic Learning: A New Rules to Predict

10.12928/telkomnika.v15i3.4286
Christina; STEI-Institut Teknologi Bandung Juliane , Arry A.; STEI-Institut Teknologi Bandung Arman , Husni S.; STEI-Institut Teknologi Bandung Sastramihardja , Iping; STEI-Institut Teknologi Bandung Supriana
Research affirms that electronic learning (e-learning) has a great deal of advantages to learning process, it’s provides learners with flexibility in terms of time, place, and pace. That easiness was not be a guarantee of a good learning outcomes though they got the same learning material and course, because the fact is the outcomes was not the same from one to another and even not satisfy enough. One of prerequisite to the successful of e-learning process is the presence of learning motivation and it was not easy to identify. We propose a novel model to predicting the presence of learning motivation in e-learning using those attributes that have been identified in previous research. This model has been built using WEKA toolkit by comparing fourteen algorithms for Tree Classifier and ten-fold cross validation testing methods to process 3.200 of data sets. The best accuracy reached at 91.1% and identified four parameters to predict the presence of learning motivation in e-learning, and aim to assist teachers in identify whether student needs motivation or does not. This study also confirmed that Tree Classifier still has the best accuracy to predict and classify academic performance, it was reached average 90.48% for fourteen algorithm for accuracy value.
Volume: 15
Issue: 3
Page: 1223-1229
Publish at: 2017-09-01

Thermal Condition and Losses in Ultra-High-Speed Generators

10.12928/telkomnika.v15i3.6365
Flur; Ufa State Aviation Technical University Ismagilov , Viacheslav; Ufa State Aviation Technical University Vavilov , Ruslan; Ufa State Aviation Technical University Karimov , Denis; Ufa State Aviation Technical University Gusakov
In this paper ultra-high-speed generators operated in intermittent periodic and short-term mode were considered. Experimental studies of losses depending on frequencies in the magnetic core of microelectromechanical energy converters made from amorphous steel were made. Dependence of the flux density from the temperature in the air gap of the experimental layout of high-coercivity permanent magnets was obtained. Computer modeling of the magnetic field distribution on the cross section of the stator magnetic core of microelectromechanical energy converters were made in the software package Ansoft Maxwell. Dependence of friction losses of the rotor around the air from the air temperature was obtained. Comparisons of losses and efficiency of microelectromechanical energy converters in a cold state and after 10 minutes of operation without cooling were made.
Volume: 15
Issue: 3
Page: 995-1002
Publish at: 2017-09-01
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