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31,377 Article Results

Dynamic Frequency Scaling Regarding Memory for Energy Efficiency of Embedded Systems

10.11591/ijece.v8i3.pp1798-1804
Junha Kim , Moonju Park
Memory significantly affects the power consumption of embedded systems as well as performance. CPU frequency scaling for power management could fail in optimizing the energy efficiency without considering the memory access. In this paper, we analyze the power consumption and energy efficiency of an embedded system that supports dynamic scaling of frequency for both CPU and memory access. The power consumption of the CPU and the memory is modeled to show that the memory access rate affects the energy efficiency and the CPU frequency selection. Based on the power model, a method for frequency selection is presented to optimize the power efficiency which is measured using Energy-Delay Product (EDP). The proposed method is implemented and tested on a commercial smartphone to achieve about 3.3% - 7.6% enhancement comparing with the power management policy provided by the manufacturer in terms of EDP.
Volume: 8
Issue: 3
Page: 1798-1804
Publish at: 2018-06-01

Evaluation of Synchronization and MPPT algorithms in a DFIG Wind Turbine Controlled by an Indirect Matrix Converter

10.11591/ijpeds.v9.i2.pp784-794
Ahmad Khajeh , Reza Ghazi , Mohamad Hosseini Abardeh , Mahmoud Oukati Sadegh
Most of generators utilized in wind turbines are the Doubly-Fed Induction Generator (DFIG). Indirect matrix converter (IMC) is a candidate for substituting the traditional back-to-back converter in the future due to advantages gained by elimination of electrolytic capacitor. Starting DFIG wind turbines and synchronizing to the grid is a challenge in practice because of large inrush currents that could damage switches. Synchronizing the DFIG wind turbine controlled by the IMC is presented in this paper. Also, maximum power point tracking algorithm performance of this configuration is examined. A laboratory scale prototype of the proposed configuration is built. Experimental results have confirmed effectiveness of this configuration.
Volume: 9
Issue: 2
Page: 784-794
Publish at: 2018-06-01

Soft Frequency Reuse (SFR) in LTE-A Heterogeneous Networks based upon Power Ratio Evaluation

10.11591/ijece.v8i3.pp1569-1576
Alvita Maurizka , F. Hamdani , M. M. Ulfah , Iskandar Iskandar
As the traffic demand grows and the RF environment changes, the mobile network relies on techniques such as SFR in Heterogeneous Network (HetNet) to overcome capacity and link budget limitation to maintain user experience. Inter-Cell Interference (ICI) strongly affecting Signal-to-Interference plus Noise Ratio (SINR) of active UEs, especially cell-edge users, which leads to a significant degradation in the total throughput. In this paper we evaluate the performance of SFR with HetNet system in order dealing with interferences. Simulation result shows that the power ratio control in SFR HetNet system doesn’t have much effect on total achieved capacity for overall cell.
Volume: 8
Issue: 3
Page: 1569-1576
Publish at: 2018-06-01

Simulation Models of Energy Cables in SPICE

10.11591/ijpeds.v9.i2.pp744-749
Uma Balaji
Accurate modeling of cables is important to study the behavior of high frequency disturbances in power converter systems. This paper reviews and compares two popular methodologies to model energy cables – an improved per unit length parameters based model and a Laplace SPICE element based model. The two models presented take into account the frequency dependence of the parameters of the cable. A ladder network is used for this purpose in the per unit length based model. The Laplace SPICE element model is generated from from a rational function approximation for the admittance parameters that are frequency dependant. The rational function approximation is obtained using a well known vector fitting algorithm.  The time and frequency domain solutions of a two wire energy cable, obtained from the two models, agree well.
Volume: 9
Issue: 2
Page: 744-749
Publish at: 2018-06-01

A Compact Dual Band Elliptical Microstrip Antenna for Ku/K Band Satellite Applications

10.11591/ijece.v8i3.pp1596-1601
Mohamed Mahfoudh Harane , Hassan Ammor
This paper presents an original elliptical microstrip patch antenna is proposed for Ku/K band satellite applications. The proposed antenna has a simple structure, small size with dimensions of about 10×12×1.58 mm³. The antenna has been designed and simulated on an FR4 substrate with dielectric constant 4.4 and thickness of 1.58 mm. The design is simulated by two different electromagnetic solvers. The results from the measured data show that the antenna has two resonant frequencies that define 2 bandwidths, defined by a return loss of less than -10 dB, and are: (14.44 GHz, 829 MHz) and (21.05 GHz, 5126 MHz),with the gain 5.59 dB and 5.048 dB respectively. The proposed antenna can be used in many applications such as in satellite, and wireless communications.
Volume: 8
Issue: 3
Page: 1596-1601
Publish at: 2018-06-01

Dynamic Voltage Stability Comparison of Thermal and Wind Power Generation with Different Static and Dynamic Load Models

10.11591/ijece.v8i3.pp1401-1411
Lina F. Acevedo , Gilbert Bothia-Vargas , John Edwin Candelo
This paper presents a static and dynamic voltage stability analysis of a power network with thermal and wind generation considering static and dynamic load models. The thermal plant was modeled as a synchronous machine and the wind farm as a variable speed induction generator based on a doubly-fed induction generator. The load considered the ZIP, exponential recovery, induction motor, and frequency-dependent load models. The bifurcation points were found by continuation power flow and sensitivity analyses. In addition, dynamic voltage stability assessments were performed considering changes in the moment of inertia and the frequency parameters. All simulations were carried out in a 4-bus power system and using the power system analysis toolbox (PSAT) and MATLAB script code. The results show that the thermal generator had difficulties to maintain stability under dynamic load variations and frequency changes, the wind generator had difficulties to maintain voltage for the load with induction motors, and both generators had difficulties when the moment of inertia is increased.
Volume: 8
Issue: 3
Page: 1401-1411
Publish at: 2018-06-01

A Survey of Machine Learning Techniques for Self-tuning Hadoop Performance

10.11591/ijece.v8i3.pp1854-1862
Md. Armanur Rahman , J. Hossen , Venkataseshaiah C , CK Ho , Tan Kim Geok , Aziza Sultana , Jesmeen M. Z. H. , Ferdous Hossain
The Apache Hadoop framework is an open source implementation of MapReduce for processing and storing big data. However, to get the best performance from this is a big challenge because of its large number configuration parameters. In this paper, the concept of critical issues of Hadoop system, big data and machine learning have been highlighted and an analysis of some machine learning techniques applied so far, for improving the Hadoop performance is presented. Then, a promising machine learning technique using deep learning algorithm is proposed for Hadoop system performance improvement.
Volume: 8
Issue: 3
Page: 1854-1862
Publish at: 2018-06-01

Modeling and Nonlinear Control of a Wind Turbine System Based on a Permanent Magnet Synchronous Generator Connected to the Three-phase Network

10.11591/ijpeds.v9.i2.pp766-774
Yasser Boussairi , Abdelmajid Abouloifa , Ibtissam Lachkar , Abdellatif Hamdoun , Chaouqi Aouadi
This article presents nonlinear control of wind conversion chain connected to the grid based on a permanent magnet synchronous generator. The control objectives are threefold; i) forcing the generator speed to track a varying reference signal in order to extract the maximum power at different wind speed (MPPT); ii) regulating the rectifier output capacitor voltage; iii) reducing the harmonic and reactive currents injected in the grid. This means that the inverter output current must be sinusoidal and in phase with the AC supply voltage (PFC). To this end, a nonlinear state-feedback control is developed, based on the average nonlinear model of the whole controlled system. This control strategy involves backstepping approach, Lyapunov stability and other tools from theory of linear systems. The proposed state-feedback control strategy is tested by numerical simulation which shows that the developed controller reaches its objectives
Volume: 9
Issue: 2
Page: 766-774
Publish at: 2018-06-01

An Empirical Comparative Study of Instance-based Schema Matching

10.11591/ijeecs.v10.i3.pp1266-1277
Mogahed Alzeber , Ali A. Alwan , Azlin Nordin , Abedallah Zaid Abualkishik
The main issue concern of schema matching is how to support the merging decision by providing matching between attributes of different schemas. There have been many works in the literature toward utilizing database instances to detect the correspondence between attributes. Most of these previous works aim at improving the match accuracy. We observed that no technique managed to provide an accurate matching for different types of data. In other words, some of the techniques treat numeric values as strings. Similarly, other techniques process textual instance, as numeric, and this negatively influences the process of discovering the match and compromising the matching result. Thus, a practical comparative study between syntactic and semantic techniques is needed. The study emphasizes on analyzing these techniques to determine the strengths and weaknesses of each technique. This paper aims at comparing two different instance-based matching techniques, namely: (i) regular expression and (ii) Google similarity to identify the match between attributes. Several analyses have been conducted on real and synthetic data sets to evaluate the performance of these techniques with respect to Precision (P), Recall (R) and F-Measure.
Volume: 10
Issue: 3
Page: 1266-1277
Publish at: 2018-06-01

Analysis and Design of Single Phase High Efficiency Transformer less PV Inverter Topology

10.11591/ijpeds.v9.i2.pp730-737
Jayalakshmi N. S. , Ankit Kumar , Ashish Kumar
An inclination towards renewable energy resources has been increased due to the requirement of clean environment and to satisfy the increasing power demand for the long run. A grid connected system requires the availability of a transformer in its power conversion stages that provides galvanic isolation between the grid and the power system. But inclusion of transformer results in making the system bulky and more expensive. In this paper different transformer-less PV inverter topologies are analyzed by comparing their efficiency, leakage current and THD of load current using MATLAB/Simulink environment. In order to achieve maximum power, maximum power point tracking (P&O algorithm) is used. From the simulation results, modified HB-ZVR is found to have minimum leakage current and constant common mode voltage with higher efficiency. Also, the hardware results are obtained for modified HB-ZVR topology.
Volume: 9
Issue: 2
Page: 730-737
Publish at: 2018-06-01

Impacts of Photovoltaic Distributed Generation Location and Size on Distribution Power System Network

10.11591/ijpeds.v9.i2.pp905-913
N. Md. Saad , M. Z. Sujod , Lee Hui Ming , M. F. Abas , M. S. Jadin , M. R. Ishak , N. R. H. Abdullah
As the rapid development of photovoltaic (PV) technology in recent years with the growth of electricity demand, integration of photovoltaic distributed generation (PVDG) to the distribution system is emerging to fulfil the demand. There are benefits and drawbacks to the distribution system due to the penetration of PVDG. This paper discussed and investigated the impacts of PVDG location and size on distribution power systems. The medium voltage distribution network is connected to the grid with the load being supplied by PVDG. Load flow and short circuit calculation are analyzed by using DigSILENT Power Factory Software. Comparisons have been made between the typical distribution system and the distribution system with the penetration of PVDG. Impacts in which PVDG location and size integrates with distribution system are investigated with the results given from the load flow and short circuit analysis. The results indicate positive impacts on the system interconnected with PVDG such as improving voltage profile, reducing power losses, releasing transmission and distribution grid capacity. It also shows that optimal locations and sizes of DGs are needed to minimize the system’s power losses. On the other hand, it shows that PVDG interconnection to the system can cause reverse power flow at improper DG size and location and increases short circuit level.
Volume: 9
Issue: 2
Page: 905-913
Publish at: 2018-06-01

Uncertain DC-DC Zeta Converter Control in Convex Polytope Model Based on LMI Approach

10.11591/ijpeds.v9.i2.pp829-838
Hafez Sarkawi , Yoshito Ohta
A dc-dc zeta converter is a switch mode dc-dc converter that can either step-up or step-down dc input voltage. In order to regulate the dc output voltage, a control subsystem needs to be deployed for the dc-dc zeta converter. This paper presents the dc-dc zeta converter control. Unlike conventional dc-dc zeta converter control which produces a controller based on the nominal value model, we propose a convex polytope model of the dc-dc zeta converter which takes into account parameter uncertainty. A linear matrix inequality (LMI) is formulated based on the linear quadratic regulator (LQR) problem to find the state-feedback controller for the convex polytope model. Simulation results are presented to compare the control performance between the conventional LQR and the proposed LMI based controller on the dc-dc zeta converter. Furthermore, the reduction technique of the convex polytope is proposed and its effect is investigated.
Volume: 9
Issue: 2
Page: 829-838
Publish at: 2018-06-01

Predictive Approach for Power Quality Improvement Based Direct Power Control

10.11591/ijpeds.v9.i2.pp668-678
Houssam Eddine Medouce , Hocine Benalla
The extensive use of non-linear loads in industry becomes increasingly a serious problem that affects the quality of energy delivered to customers. Therefore, the shunt active power filter (SAPF) has emerged as an important industrial tool to eliminate induced harmonic currents   and compensating of reactive power. This paper proposes an improved control configuration for SAPF based on a modern technique called predictive direct power control (Predictive-DPC). The principle of this control is based on the direct regulation of the instantaneous active and reactive powers to guarantee a good energy quality on the grid side. For this purpose the appropriate average voltage vector which cancels power tracking errors is calculated by a simple predictive model at the bigining of each control period. This type of control includes various features such as the lack of look up table (LUTs) and closed current loops and the constant switching frequency is achieved through the use of PWM modulation.  The results of the simulation process show a high performance in the steady and transient state function for predictive-DPC control that might be a reasonable alternative to conventional DPC in the field of active power filtering.
Volume: 9
Issue: 2
Page: 668-678
Publish at: 2018-06-01

Ultra Thin Flexible Octagonal Metamaterials Absorber

10.11591/ijeecs.v10.i3.pp833-839
H. Hassan , M. Abu
An ultra thin flexible octagonal metamaterial absorber on 0.13 mm fastFilm D27 material has been presented in this paper. CST microwave studio was used in designing and simulating the octagonal metamaterial absorber. The flexible octagonal metamaterial absorber was resonated at 10 GHz with highly perfect absorbance of 99.98%. However, Full Width Half Maximum (FWHM) of the absorbance was relatively small 135 MHz affected from the ultra thin substrate used. By using triangular lattice arrangement of the unit cell, the FWHM could be increased to 171 MHz. Besides that, combination of resonating frequencies technique also had increased the FWHM more than 74% increment from basic unit cell with one resonance frequency. The flexibleness of the metamaterial absorber could increase the functionality of the metamaterial absorber to be used in any application especially in reducing radar cross section for stealth application.
Volume: 10
Issue: 3
Page: 833-839
Publish at: 2018-06-01

Pulse Density Modulation Based Series Resonant Inverter Fed Induction Heater System

10.11591/ijpeds.v9.i2.pp690-697
S. Jaanaa Rubavathy , P. Murugesan
This paper deals with implementation of a multi-output Series Resonant Inverter(SRI) for induction heating applications, which uses pulse density modulation(PDM) control for full bridge Series resonant inverters for output voltage and power control. It ensures better efficiency performances than conventional control strategies. The proposed converter can be considered as a two output extension of a full bridge inverter. This full bridge inverter can control the two outputs, simultaneously and independently, up to their rated powers, which reduces the usage of number of components as compared with conventional method. It also ensures higher utilization of switches used for its operation. A two output full bridge series resonant inverter is simulated and implemented. The Experimental results are compared with the simulation results.
Volume: 9
Issue: 2
Page: 690-697
Publish at: 2018-06-01
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