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26,833 Article Results

The Pessimistic Investor Sentiments Indicator in Social Networks

10.12928/telkomnika.v15i3.5360
Rui; Harbin Institute of Technology Jin , Hong-Li; Harbin Institute of Technology Zhang , Xing; Harbin Institute of Technology Wang , Xiao-Meng; Harbin Institute of Technology Wang
With the worldwide proliferation of social networks, the social networks have played an important role in the social activities .Peoples are inclined to obtain the corresponding public opinion to make decision such as shopping, education, investment and so on. Analysis of data generated by social networks has become an important field of research, however in the field of public opinion analysis of social networks the quantitative measure indexes are still lacking. In this paper, the calculation method of pessimistic investor sentiments indicator is proposed, and the index has a certain theoretical and practical value.
Volume: 15
Issue: 3
Page: 1328-1334
Publish at: 2017-09-01

Miniaturization of Resonator based on Moore Fractal

10.12928/telkomnika.v15i3.7211
E.; Universiti Tun Hussein Onn Malaysia (UTHM) Mohd , S.; Universiti Tun Hussein Onn Malaysia (UTHM) H. Dahlan
This paper presents the simulation and fabrication of miniaturized half wavelength resonator design using Moore fractal iteration technique. These resonators have been prepared for wireless application at a centre frequency of 2.45GHz using a substrate with dielectric constant of 2.2. The size and performance are compared with the conventional half wavelength open line resonator. It can be shown that the Moore fractal iteration technique able to reduce 46% of the size of conventional half wavelength resonator through first iteration, and 30% through second iteration while maintaining the resonance performance. The resonators have been fabricated using conventional printed circuit board facilities not specialized in microwave devices. However, the unloaded Q-value of the Moore structure generally much lower compared the open line type.
Volume: 15
Issue: 3
Page: 1433–1439
Publish at: 2017-09-01

Integral Backstepping Approach for Mobile Robot Control

10.12928/telkomnika.v15i3.5667
Bouzgou; University of Sciences and Technology of Oran USTO/MB. Oran Kamel , Ibari; University of Sciences and Technology of Oran USTO/MB. Oran Benaoumeur , Benchikh; University of Evry Laredj , Ahmed-Foitih; University of Sciences and Technology of Oran USTO/MB. Oran Zoubir
This paper presents the trajectory tracking problem of a unicycle-type mobile robots. A robust output tracking controller for nonlinear systems in the presence of disturbances is proposed, the approach is based on the combination of integral action and Backstepping technique to compensate for the dynamic disturbances. For desired trajectory, the values of the linear and angular velocities of the robot are assured by the kinematic controller. The control law guarantees stability of the robot by using the lyapunov theorem. The simulation and experimental results are presented to verify the designed trajectory tracking control.
Volume: 15
Issue: 3
Page: 1173-1180
Publish at: 2017-09-01

A Novel Analysis of Improving Displacement Factor Using IVDFC in Distribution Systems

10.11591/ijaas.v6.i3.pp193-202
M. Padmarasan , C.T. Manikandan , N. Karthikeyan , L. Jayaprakash , C.S. Ajin Sekhar
In this paper discuss the new approach for improving displacement factor using an Interline Dynamic Voltage Restoring and Displacement Factor Controlling Device (IVDFC) in a distribution system. An Interline Dynamic Voltage Restorer (IDVR) is perpetually engaged in distribution systems to mitigate voltage sag/swell problems. An IDVR simply consists of numerous dynamic voltage restorers (DVRs) sharing a common dc link connecting independent feeders to safe electric power to critical loads. The IDVR is operated that it hold the voltage across the critical load bus terminals constant at system nominal frequency irrespective of the changes occurring in source voltages frequency. While one of the DVRs compensates for the local voltage sag in its feeder, the other DVRs reload the common dc-link voltage. For normal voltage levels, the DVRs should be bypassed. Instead of bypassing the DVRs in normal conditions, this paper proposes operating the DVRs, if needed, to improve the displacement factor (DF) of one of the involved feeders. DF improvement can be achieved via active and reactive power exchange (PQ sharing) between different feeders. To successfully apply this concept, several constraints are addressed throughout the paper. The simulation model for this system is developed using MATLAB which is shown that the voltage across the critical load is regulated completely.
Volume: 6
Issue: 3
Page: 193-202
Publish at: 2017-09-01

The Performance of an Integrated Transformer in a DC/DC Converter

10.12928/telkomnika.v15i3.4251
Abdelhadi; USTO-MB University Namoune , Azzedine; USTO-MB University Hamid , Rachid; Hassiba Benbouali University Taleb
The separation between the low-voltage part and high-voltage part of the converter is formed by a transformer that transfers power while jamming the DC ring. The resonant mode power oscillator is utilized to allow elevated competence power transfer. The on-chip transformer is probable to have elevated value inductance, elevated quality factors and elevated coupling coefficient to decrease the loss in the oscillation. The performance of a transformer is extremely dependent on the structure, topology and other essential structures that create it compatible with the integrated circuits IC process such as patterned ground shield (PGS). Different types of transformers are modeled and simulated in MATLAB; the performances are compared to select the optimum design. The on-chip transformer model is simulated and the Results of MATLAB simulation are exposed, showing an excellent agreement in radio frequency RF.
Volume: 15
Issue: 3
Page: 1031-1039
Publish at: 2017-09-01

Fuzzy Logic Implementation with MATLAB for PV-Wind Hybrid System

10.12928/telkomnika.v15i3.6099
Alias; Universiti Teknikal Malaysia Melaka Khamis , Mohd Ruddin; Universiti Teknikal Malaysia Melaka Ab. Ghani , Chin Kim; Universiti Teknikal Malaysia Melaka Gan , Mohd Shahrieel; Universiti Teknikal Malaysia Melaka Mohd Aras , Muhamad Fiqry; Universiti Teknikal Malaysia Melaka Khamis , Tole; Universitas Ahmad Dahlan Sutikno , Jano; Universiti Teknikal Malaysia Melaka Zanariah
This paper is under in-depth investigation due to suspicion of possible plagiarism on a high similarity indexThe development of hybrid renewable energy sources is vital in power generation. This study focused on design of fuzzy logic control on hybrid PV/Wind system in order to improve the speed of DC motor. The fuzzy logic control based on battery management system has been designed for effective power utilization and improvement of the DC motor speed performance. In battery management system, a control was proposed to operate the charging and discharging mode of battery during non-linear power generation. While the battery would charge whenever the renewable energy power was greater than consumer load power, the battery would discharge whenever the renewable energy power was less than the consumer load power. DC motor speed control, included the simulation, implementation of fuzzy logic controller to DC motor and comparison between PID controller and Fuzzy Logic Controller. The proposed model was simulated using Matlab environment and the results was analyzed. Finally, simulation results were evaluated and validated to determine the effectiveness of the proposed controller.
Volume: 15
Issue: 3
Page: 1181-1191
Publish at: 2017-09-01

Examining Pre-school Teachers’ and Parents’ Views on Counseling and Guidance Services in Pre-school Education

10.11591/ijere.v6i3.7639
Gulsen Buyuksahin Cevik
Current study aims to reveal the problems that pre-school teachers and parents face, in relation to guidance and counseling services, at schools without psychological counselors. The purpose of including pre-school teachers and parents in the current study was to find out both whether they considered the guidance and counseling services a need and whether their methods of intervention against the problems that they face were functional. The current research was designed with interview technique as a qualitative study method. Research data were collected through a semi-structured interview form developed by the researcher. The researcher met the participants individually and asked the questions on the interview form for the current research. The responses that the participants provided were recorded and later transferred onto computer environment. The study group, formed based on voluntary participation, included total 30 participants with 15 pre-school teachers and 15 parents of pre-school children. Pre-school teacher participants 10 females and 5 males, worked for five different preschools in Adiyaman. Total 15 parents in the study group included nine females and six males. An examination of pre-school teachers’ responses based on the current study findings indicated that majority of the teachers did not prepare an annual counseling and guidance plan. Another finding of the current study was that children of most parents and teachers experience adjustment problems in pre-school. Another finding of the current research is about children’s individual problems. Main individual problems that parents experienced with their children included self-care and social development.
Volume: 6
Issue: 3
Page: 207-215
Publish at: 2017-09-01

Online Monitoring of Grid Connected Residential Photovoltaic System using Zigbee and Web Server

10.11591/ijeecs.v7.i3.pp668-675
Syafii Ghazali , Roni Putra , Hasdi Putra
The paper presents grid-tied PV monitoring system using wireless sensor networks.  The temperature and humidity parameters were measured using DHT22. While ACS 712 5A current sensor and Arduino voltage sensor modules were used to measure photovoltaic output current and voltage respectively. Web application has been developed in the base station using PHP programming web server to access the sensor nodes through Zigbee wireless data communication. The user can access the HTML web interface of Photovoltaic monitoring system through local Ethernet or Wi-Fi connection. The residential 1.25 kWp grid connected photovoltaic system used to test the developed monitoring system. The data received exactly same as data sensed from remote area with average delay time 3 to 4 seconds. The result shows the photovoltaic power generation caracteristics under clear sky, cloud cover, and rainy weather conditions. The power 608.12 Wp has been generated by the solar panel from 7.00 am to 6.00 pm or 6.7 kWh per day during clear sky. During intermittent cloud covered the photovoltaic power graph have shown fluctuation power profile and energy conversion were decreased as well as in raining weather condition. The electrical power has been generated by photovoltaic for almost 12 hours per day in tropics area, but energy conversion is highly influenced by weather conditions, especially cloud cover, overcast and rainy.
Volume: 7
Issue: 3
Page: 668-675
Publish at: 2017-09-01

A Novel Space-time Discontinuous Galerkin Method for Solving of One-dimensional Electromagnetic Wave Propagations

10.12928/telkomnika.v15i3.5080
Pranowo; Teknik Informatika Universitas Atma Jaya Yogyakarta Pranowo
In this paper we propose a high-order space-time discontinuous Galerkin (STDG) method for solving of one-dimensional electromagnetic wave propagations in homogeneous medium. The STDG method uses finite element Discontinuous Galerkin discretizations in spatial and temporal domain simultaneously with high order piecewise Jacobi polynomial as the basis functions. The algebraic equations are solved using Block Gauss-Seidel iteratively in each time step. The STDG method is unconditionally stable, so the CFL number can be chosen arbitrarily. Numerical examples show that the proposed STDG method is of exponentially accuracy in time.
Volume: 15
Issue: 3
Page: 1310-1316
Publish at: 2017-09-01

Planar Microwave Sensors for Accurate Measurement of Material Characterization: A Review

10.12928/telkomnika.v15i3.6684
Norhanani; Universiti Teknikal Malaysia Melaka Abd Rahman , Zahriladha; Universiti Teknikal Malaysia Melaka Zakaria , Rosemizi; University Malaysia Perlis Abd Rahim , Yosza; Universiti Teknikal Malaysia Melaka Dasril , Amyrul Azuan; Universiti Teknikal Malaysia Melaka Mohd Bahar
Microwave sensor is used in various industrial applications and requires highly accurate measurements for material properties. Conventionally, cavity waveguide perturbation, free-space transmission, open-ended coaxial probe, and planar transmission line technique have been used for characterizing materials. However, these planar transmission lines are often large and expensive to build, further restricting their use in many important applications. Thus, this technique is cost effective, easy to manufacture and due to its compact size, it has the potential to produce sensitivity and a high Q-factor for various materials. This paper reviews the common characteristics of planar transmission line and discusses numerous studies about several designs of the microstrip resonator to improve the sensor performance in terms of the sensitivity and accuracy. This technique enables its use for several industrial applications such as agriculture and quality control. It is believed that previous studies would lead to a promising solution of characterizing materials with high sensitivity, particularly in determining a high Q-factor resonator sensor.
Volume: 15
Issue: 3
Page: 1108-1118
Publish at: 2017-09-01

Design of Circular Patch with Double C-Shaped Slot Microstrip Antenna for LTE 1800 MHz

10.12928/telkomnika.v15i3.5492
Yusnita; Universitas Riau Rahayu , Jherino Permana; Universitas Riau Putra
The design of a circular patch microstrip antenna with double C-shaped for LTE 1800 MHz is presented. The antenna is designed using FR-4 with dielectric constant of ε = 4.3, with thickness of substrate that is 1.6 mm and the thickness of patch and ground are 0.025 mm, Respectively the simulation results presented that the antenna works at frequency of 1714-1889.6 MHz, and work very well at frequency of 1800 MHz with a Return loss -20.484 dB, bandwidth 175.6 MHz. Technique used for broaden the bandwidth by using double C-shaped slot. In this paper presents S-Parameters, and Gain of microstrip antenna circular patch with double C-shaped slot.
Volume: 15
Issue: 3
Page: 1079-1082
Publish at: 2017-09-01

Numerical Simulation of Highly-Nonlinear Dispersion-Shifted Fiber Optical Parametric Gain Spectrum with Fiber Loss and Higher-Order Dispersion Coefficients

10.12928/telkomnika.v15i3.7215
K.; Universiti Tun Hussein Onn Malaysia G. Tay , N.; Universiti Tun Hussein Onn Malaysia Othman , N.; Universiti Tun Hussein Onn Malaysia S. M. Shah , N.; Universiti Tun Hussein Onn Malaysia A. Cholan
The previous study investigated the fiber parameters on the analytical one-pump fiber optical parametric amplifier (FOPA) gain spectrum of a loss-free highly-nonlinear dispersion-shifted fiber (HNL-DSF) and got the optimum results for each parameter. However, the FOPA gain of the combination of all the optimum values of the considered parameters was not reported. Hence, this paper intends to investigate the analytical FOPA gain of the combination of all the optimum values of the considered parameters from the previousstudy. Later, the analytical gain was compared with the numerical gain from the fourth-order Runge-Kutta (RK4) method and Matlab built-in function, ode45. Next, the effect of fiber loss and higher order dispersioncoefficients such as fourth and sixth-order dispersion coefficients were studied. It is found that RK4 gives a smaller error and the gain reduces while the bandwidth remains same in presence of fiber loss. Thefourth-order dispersion coefficient broadens the bandwidth a bit while maintaining the gain and there are two narrow-band gains generated to the left and right-side of the broad-band gain. The sixth-order dispersioncoefficient just shifts the two narrow-band gains toward or away from the broadband gain depending on the positive or negative signs of the sixth-order dispersion coefficient.
Volume: 15
Issue: 3
Page: 1461-1469
Publish at: 2017-09-01

Analysis of Memory Effects in Digital Filters with Overflow Arithmetic

10.11591/ijeecs.v7.i3.pp755-760
Mani Kant Kumar , Haranath Kar
This paper deals with the problem of undesired memory effects in nonlinear digitalfilters owing to the influence of past excitations on future outputs. The nonlinearities under consideration cover the usual types of overflow arithmetic employed in practice. Based on the Hankel norm performance, a new criterion is proposed to ensure the reduction of undesired memory effects in digital filters with overflow arithmetic. In absence of external input, the nonexistence of overflow oscillations is also confirmed by the proposed criterion. A numerical example together with simulation result showing the effectiveness of the criterion is given.
Volume: 7
Issue: 3
Page: 755-760
Publish at: 2017-09-01

Decision Support System for Bat Identification using Random Forest and C5.0

10.12928/telkomnika.v15i3.3638
Deden Sumirat; Bogor Agricultural University ; Research Center for Biology-LIPI Hidayat , Imas Sukaesih; Bogor Agricultural University Sitanggang , Gono; Research Center for Biology-LIPI Semiadi
Morphometric and morphological bat identification are a conventional method of identification and requires precision, significant experience, and encyclopedic knowledge. Morphological features of a species may sometimes similar to that of another species and this causes several problems for the beginners working with bat taxonomy. The purpose of the study was to implement and conduct the random forest and C5.0 algorithm analysis in order to decide characteristics and carry out identification of bat species. It also aims at developing supporting decision-making system based on the model to find out the characteristics and identification of the bat species. The study showed that C5.0 algorithm prevailed and was selected with the mean score of accuracy of 98.98%, while the mean score of accuracy for the random forest was 97.26%. As many 50 rules were implemented in the DSS to identify common and rare bat species with morphometric and morphological attributes.
Volume: 15
Issue: 3
Page: 1215-1222
Publish at: 2017-09-01

Weighted Least Squared Approach to Fault Detection and Isolation for GPS Integrity Monitoring

10.12928/telkomnika.v15i3.5800
Ershen; Shenyang Aerospace University Wang , Fuxia; Shenyang Aerospace University Yang , Pingping; Shenyang Aerospace University Qu , Tao; Shenyang Aerospace University Pang , Xiaoyu; Shenyang Aerospace University Lan
Reliability of a global navigation satellite system is one of great importance for global navigation purposes. Therefore, an integrity monitoring system is an inseparable part of aviation navigation system. Failures or faults due to malfunctions in the systems should be detected to keep the integrity of the system intact. In order to solve the problem that least squares method detects and isolates a satellite fault for GPS integrity monitoring, in this paper, a weighted least squares algorithm is proposed for satellite fault detection and isolation. The algorithm adopts the diagonal elements of the covariance matrix of GPS measurement equation as the weighted factor. Firstly, the weighted least squares approach for satellite fault detection establishes the test statistic by the sum of the squares of the pseudo-range residuals of each satellite for GPS. Then, the detection threshold is obtained by the false alarm rate of the fault detection, probability density function and visiable satellite number.The effectiveness of the proposed approach is illustrated in a problem of GPS (Global Positioning System) autonomous integrity monitoring system. Through the real raw measured GPS data，based on least squares RAIM method and the weighted least squares RAIM approach, the performance of the two algorithms is compared. The results show that the proposed RAIM approach is superior to the least squares RAIM algorithm in the sensitivity of fault detection and fault isolation performance for GPS integrity monitoring.
Volume: 15
Issue: 3
Page: 1022-1030
Publish at: 2017-09-01
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