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23,598 Article Results

Sparse Representation for Detection of Microcalcification Clusters

10.12928/telkomnika.v10i3.835
Xinsheng; Xi’an University of Architecture and Technology Zhang , Minghu; Xi’an University of Architecture and Technology Wang , Ji Ma; Xi’an University of Architecture and Technology Ji Ma
We present an approach to detect MCs in mammograms by casting the detection problem as finding sparse representations of test samples with respect to training samples. The ground truth training samples of MCs in mammograms are assumed to be known as a priori. From these samples of the interest object class, a vocabulary of information-rich object parts is automatically constructed. The sparse representation is computed by the l1-regularized least square approach using the interior-point method. The method based on sparse representation expresses each testing sample as a linear combination of all the training samplesfrom the vocabulary. The sparse coefficient vector is obtained by l1-regularized least square through learning. MCs detectionis achieved by defining discriminatefunctions from the sparse coefficient vector for each category. To investigate its performance, the proposed method is applied to DDSM datasets and compared with support vector machines (SVMs) and twin support vector machines (TWSVMs). The experimental results have shown that the performance of the proposed method is comparable with or better than those methods. In addition, the proposed method is more efficient than SVMs and TWSVMs based methods as it has no need of model selection and parameter optimization.
Volume: 10
Issue: 3
Page: 545-550
Publish at: 2012-09-01

Water Inrush Characteristics with Roadway Excavation Approaching to Fault

10.12928/telkomnika.v10i3.830
Shuren; Yanshan University Wang , Hu Wang; Yanshan University Hu Wang
Water inrush disaster is an important factor in restricting safe production of the coal mine. Taking the roadway in seam in Danhou Coal Mine, as the engineering background, according to the spatial relationship of the roadway, the impermeable layer, the fault and the loading conditions, the fault activation mechanical model under the roadway excavation disturbance was built, and the fault activation conditions, roadway water inrush criterion and water inrush three modes were put forward. A three-dimensional numerical calculation models were built by using FLAC3D. Through fluid-solid coupling calculation, the surrounding rock damage and failure, the water inrush channel formation, and the evolution process of water inrush of the roadway excavation approaching the fault were analyzed. Moreover, the displacement field, the stress field and the surrounding rock plastic failure characteristics of the roadway were revealed. Furthermore, under the conditions of different water pressure, impermeable rock thickness, fault displacement, and fault dip angles, the roadway water inrush modes and their evolution characteristics were comparatively analyzed.
Volume: 10
Issue: 3
Page: 505-513
Publish at: 2012-09-01

Modeling and Control PV-Wind Hybrid System Based On Fuzzy Logic Control Technique

10.12928/telkomnika.v10i3.821
Doaa M.; Electronics Research Institute Atia , Faten H.; Electronics Research Institute Fahmy , Ninet M.; Electronics Research Institute Ahmed , Hassen T.; Cairo University Dorrah
As energy demands around the world increase, the need for a renewable energy sources that will not harm the environment is increased. The overall objective of renewable energy systems is to obtain electricity with competitive cost and even benefit with respect to other energy sources. The optimal design of renewable energy system can significantly improve the economical and technical performance of power supply. This paper presents the power management control using fuzzy logic control technique. Also, a complete mathematical modeling and MATLAB/Simulink model for the proposed the electrical part of an aquaculture system is implemented to track the system performance. The simulation results show the feasibility of control technique.
Volume: 10
Issue: 3
Page: 431-441
Publish at: 2012-09-01

Field Distribution of Environment and Vibration Chamber

10.12928/telkomnika.v10i3.839
Wang; Harbin Engineering University Tong , Guan; Harbin Engineering University Yin , Xu He; Harbin Engineering University Xu He , Liang; Institute of Ministry of Information Industry Qiong-chong
Environment and vibration test system can test equipment such as radars in full load condition. Environment and vibration chamber is an opening rectangular cavity. In order to study the field distribution of environment and vibration chamber, the open rectangular cavity field distribution and parabolic antenna are analyzed by using the Dyadic Green’s functions. According to the Dyadic Green’s functions, the field distribution of environment and vibration chamber is concluded by MATLAB. The simulation result of FEKO proves that the method by using Dyadic Green’s functions is available. The innovation of this article is using the Dyadic Green’s functions to analyzed open cavity field and parabolic antenna.
Volume: 10
Issue: 3
Page: 572-578
Publish at: 2012-09-01

Performance Analysis of Doubly Excited Brushless Generator with Outer Rotor for Wind Power Application

10.12928/telkomnika.v10i3.825
Yingchao; Beijing Jiaotong University Zhang , Huijuan; Beijing Jiaotong University Liu , Haijiao; Beijing Jiaotong University Zhang , Xiang; Beijing Jiaotong University Zhao
In this paper, a novel doubly excited brushless generator (DEBG) with outer radial laminated magnetic barrier rotor (RLMB-rotor) for wind power application was designed and analyzed. The DEBG has 10 rotor pole numbers with outer rotor. Its performance was investigated using the 2D transient finite element method. The magnetic fields, torque capability, end winding voltage characteristics, radial magnetic force and energy efficiency were analyzed. All studies in this paper show that the simplicity, reliability, high efficiency and low vibration and noise of the DEBG with outer rotor were attractive for variable speed constant frequency (VSCF) wind power generation system.
Volume: 10
Issue: 3
Page: 471-476
Publish at: 2012-09-01

Retinal Image Preprocessing: Background and Noise Segmentation

10.12928/telkomnika.v10i3.834
Ibaa; National University of sciences & Technology Jamal , M. Usman; National University of sciences & Technology Akram , Anam; National University of sciences & Technology Tariq
Medical imaging is very popular research area these days and includes computer aided diagnosis of different diseases by taking digital images as input. Digital retinal images are used for the screening and diagnosis of diabetic retinopathy, an eye disease. An automated system for the diagnosis of diabetic retinopathy should highlight all signs of disease present in the image and in order to improve the accuracy of the system, the retinal image quality must be improved. In this article, we present a method to improve the quality of input retinal image and we consider this method as a preprocessing step in automated diagnosis of diabetic retinopathy. The preprocessing consists of background estimation and noise removal from retinal image by applying coarse and fine segmentation. We perform extensive results to check the validity of proposed preprocessing technique using standard fundus image database.
Volume: 10
Issue: 3
Page: 537-544
Publish at: 2012-09-01

Modeling of Maximum Power Point Tracking Controller for Solar Power System

10.12928/telkomnika.v10i3.819
Aryuanto; National Institute of Technology Malang Soetedjo , Abraham; National Institute of Technology Malang Lomi , Yusuf Ismail; National Institute of Technology Malang Nakhoda , Awan Uji; National Institute of Technology Malang Krismanto
 In this paper, a Maximum Power Point Tracking (MPPT) controller for solar power system is modeled using MATLAB Simulink. The model consists of PV module, buck converter, and MPPT controller. The contribution of the work is in the modeling of buck converter using equation model approach rather than circuit model one.  The buck converter model is developed using equation model that allowing the input voltage of the converter, i.e. output voltage of PV is changed by varying the duty cycle, so that the maximum power point could be tracked when the environmental changes. From the experiment, the developed model comforms with the circuit model provided by MATLAB Simulink Power Simulation. Furher, the simulation results show that the developed model performs well in tracking the maximum power point (MPP) of the PV module using Perturb and Observe (P&O) Algorithm. 
Volume: 10
Issue: 3
Page: 419-430
Publish at: 2012-09-01

Research on the Reciprocating Sealing of Fracturing Pump

10.12928/telkomnika.v10i3.829
Wei Bing; Xihua University Zhu , Gang; Xihua University Zhou , He Shun; Xihua University Wang
The failure reasons of reciprocating sealing in OPI-1800AWS fracturing pump are analyzed by scanning electron microscope technology (SEMT). The lubrication mechanism of plunger seal friction pair is analyzed by hydrodynamic lubrication theory. During its discharge and suction stroke, the reciprocating sealing friction pair meets the conditions of hydrodynamic lubrication, a certain thickness of oil film can be formed and maintained between the plunger and V-shaped sealing interface, which can lubricate sealing pair, reduce friction and improve lifetime. The axial pressure distribution of the V-shaped sealing is carried out by theoretical analysis and experimental testing. According to the distribution curve of axial pressure, the V-shaped sealing failure and the determination of the number of loops are discussed.
Volume: 10
Issue: 3
Page: 499-504
Publish at: 2012-09-01

Time of Arrival and Angle of Arrival Statistics for Distant Circular Scattering Model

10.12928/telkomnika.v10i3.838
Guo; Central South University Limei , Nian; Central South University Xiaohong
General scattering model is local scattering process assumed that the mobile station is located inside the scattering region, in order to study distant scattering model in suburban or hilly propagation environment, a geometrically based statistical distant circular scattering mode in macrocell environment was proposed, the closed-form expressions of the joint probability density function of the time of arrival /the angle of arrival, the marginal probability density function of the angle of arrival and the angle of departure, the marginal probability density function of the time of arrival were derived, this probability density function’s provided insight into the properties of the spatial distant scattering channel model.
Volume: 10
Issue: 3
Page: 564-571
Publish at: 2012-09-01

Economic Dispatch Thermal Generator Using Modified Improved Particle Swarm Optimization

10.12928/telkomnika.v10i3.824
Andi Muhammad; Khairun University Ternate Ilyas , M. Natsir; Khairun University Ternate Rahman
Fuel cost of a thermal generator is its own load functions. In this research, Modified Improved Particle Swarm Optimization (MIPSO) is applied to calculate economic dispatch. Constriction Factor Approach (CFA) is used to modify IPSO algorithm because of the advantage to improve the ability of global searching and to avoid local minimum, so that the time needed to converge become faster. Simulation results achieved by using  MIPSO method at the time of peak load of of 9602 MW, obtained generation cost is Rp 7,366,912,798,34 per hour, while generation cost of real system is Rp. 7,724,012,070.30 per hour. From the simulation result can be concluded that MIPSO can reduce the generation cost of  500 kV Jawa Bali transmission system of Rp 357,099,271.96 per hour or equal to 4,64%.
Volume: 10
Issue: 3
Page: 459-470
Publish at: 2012-09-01

An Improved Optimization Model of Internet Charging Scheme in Multi Service Networks

10.12928/telkomnika.v10i3.842
Kamaruzzaman; Islamic Science University of Malaysia Seman , Fitri Maya; Islamic Science University of Malaysia Puspita , Bachok M.; Islamic Science University of Malaysia Taib , Zurina; Islamic Science University of Malaysia Shafii
This article will analyze new improved charging scheme with base price, quality premium and QoS networks involved. Sain and Herpers [5] already attempted to obtain revenue maximization by creating charging scheme of internet. The plan is attempted to solve multi service networks scheme as an optimization model to obtain revenue maximization using our improved model based on Byun and Chatterjee [2] and Sain and Herpers [5]. The results show that improved model can be solved optimally using optimization tool LINGO to achieve better revenue maximization. Better results are obtained in all cases rather than in [5]. The advantage of our new model is that ISP also can set up their base price and quality premium based on ISP preferences. For some cases for getting revenue maximization, we do not offer one service and just utilize some of the services.
Volume: 10
Issue: 3
Page: 592-598
Publish at: 2012-09-01

Optic Nerve Head Segmentation Using Hough Transform and Active Contours

10.12928/telkomnika.v10i3.833
Handayani; Sepuluh Nopember Institute of Technology (ITS) Tjandrasa , Ari; Sepuluh Nopember Institute of Technology (ITS) Wijayanti , Nanik; Sepuluh Nopember Institute of Technology (ITS) Suciati
Optic nerve head is part of the retina where ganglion cell axons exit the eye to form the optic nerve. Glaucomatous changes related to loss of the nerve fibers decrease the neuroretinal rim and expand the area and volume of the cup. Therefore optic nerve head evaluation is important for early diagnosis of glaucoma. This study implements the detection of the optic nerve head in retinal fundus images based on the Hough Transform and Active Contour Models. The process starts with the image enhancement using homomorphic filtering for illumination correction, then proceeds with the removal of blood vessels on the image to facilitate the subsequent segmentation process. The result of the Hough Transform fitting circle becomes the initial level set for the active contour model. The experimental results show that the implemented segmentation algorithms are capable of segmenting optic nerve head with the average accuracy of 75.56% using 30 retinal images from the DRIVE database.Optic nerve head segmentation using hough transform and active contours
Volume: 10
Issue: 3
Page: 531-536
Publish at: 2012-09-01

Optimal Power Flow with Hybrid Distributed Generators and Unified Controller

10.12928/telkomnika.v10i3.818
Lakshmi; Sri Venkateswara College of Engineering Ravi , Vaidyanathan R; Sri Venkateswara College of Engineering Vaidyanathan R , Shishir; Sri Venkateswara College of Engineering Kumar D , Prathika; Sri Venkateswara College of Engineering Appaiah , S.G. Bharathi; Sri Venkateswara College of Engineering Dasan
Optimal power flow (OPF) study is conducted on a power system to achieve one of the following objectives: cost/loss minimization or available transfer capability (ATC) calculation in a deregulated environment. Distributed generation (DG) is a small source of electric power conversion from non-conventional energy sources and Hybrid DGs which often the most cost-effective and reliable way to produce power. The optimality of control variables and minimum value of objective functions in OPF study would definitely change when DGs are interconnected to the grid. The change would be respect to the location, quantity and combination of power injection by DGs. On the other hand, FACTS controllers are effective in utilizing the existing of transmission network which is very important especially in a deregulated system. Unified power flow controller (UPFC), a second generation FACTS controller, is well known for minimizing the cost of generation/losses with a good voltage profile as well as for ATC improvement. This paper conducts a detailed OPF study on a 9 bus system for the above mentioned three objectives to analyze the effect of DGs with and without UPFC. From the results, it is found that hybrid DGs along with UPFC yields better performance in many aspects.
Volume: 10
Issue: 3
Page: 409-421
Publish at: 2012-09-01

Silicon Germanium Heterojunction Bipolar Transistor for Digital Application

10.12928/telkomnika.v10i3.828
Engelin Shintadewi; Trisakti University Julian
Bipolar transistor performances can be characterized by figures of merit such as cut-off frequency, maximum frequency of oscillation and Emitter Coupled Logic gate delay. We studied the required figures of merit for digital application and the effects of lateral and vertical scaling to the figures of merit of SiGe Heterojunction Bipolar Transistor. With lateral scaling, the width of emitter finger is scaled down from 0.25 to 0.12 μm while with the vertical scaling, the base width is scaled down to reduce the base delay. We also observed the effects of Ge profile and Ge fraction to the devices performances. Bipole3 5.3.1G is used to help us in the study. We found that high frequency cut-off and maximum frequency of oscillation as well as low Emitter Coupled Logic gate delay are all important for digital applications. Scaling down the emitter finger width enhanced the maximum frequency of oscillation and reduced Emitter Coupled Logic gate delay significantly while scaling down the base width increased the cutoff frequency and current gain.
Volume: 10
Issue: 3
Page: 493-498
Publish at: 2012-09-01

A New Image Segmentation Algorithm and Its Application in Lettuce Object Segmentation

10.12928/telkomnika.v10i3.837
Jun Sun; Jiangsu University Jun Sun , Yan Wang; Jiangsu University Yan Wang , Xiaohong Wu; Jiangsu University Xiaohong Wu , Xiaodong; Jiangsu University Zhang , Hongyan; Jiangsu University Gao
Lettuce image segmentation which based on computer image processing is the premise of non-destructive testing of lettuce quality. The traditional 2-D maximum entropy algorithm has some faults, such as low accuracy of segmentation, slow speed, and poor anti-noise ability. As a result, it leads to the problems of poor image segmentation and low efficiency. An improved 2-D maximum entropy algorithm is presented in this paper. It redistricts segmented regions and furtherly classifies the segmented image pixels with the method of the minimum fuzzy entropy, and reduces the impact of noise points, as a result the image segmentation accuracy is improved. The improved algorithm is used to lettuce object segmentation, and the experimental results show that the improved segmentation algorithm has many advantages compared with the traditional 2-D maximum entropy algorithm, such as less false interference, strong anti-noise ability, good robustness and validity.
Volume: 10
Issue: 3
Page: 557-563
Publish at: 2012-09-01
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