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29,905 Article Results

Low Voltage Ride-through for Doubly Fed Induction Generator Using Battery-Storage System

10.11591/ijpeds.v7.i2.pp481-497
D.V.N. Ananth , G.V. Nagesh Kumar
In this paper, enhanced field oriented control technique (EFOC) was adopted in Rotor Side Control (RSC) of DFIG converter for improved response during severe faults. The work is intended to damp pulsations in electromagnetic torque, improve voltage mitigation and limit surge currents and to enhance the operation of DFIG during voltage sags. The converter topology uses a battery energy storage system with capacitor storage system to further enhance operation of DFIG during faults. The battery and capacitor system in coordination provide additional real and reactive power support during faults and nearly constant voltage profile at stator and rotor terminals and limit overcurrents. For EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process DC-Offset component of flux is controlled, decomposition during overvoltage faults. The offset decomposition of flux will be oscillatory in a conventional FOC, whereas in EFOC it will damp quickly. A comparison is made with proposed methodology with battery energy storage system and a conventional system. Later the system performance with under voltage of 50% the rated voltage with fault at PCC during 0.8 to 1.2 seconds is analysed using simulation studies.
Volume: 7
Issue: 2
Page: 481-497
Publish at: 2016-06-01

Synthesis and Implementation (In STM8S) of Phased Circular Antenna Arrays Using Taguchi Method

10.11591/ijece.v6i3.pp1077-1085
Nadhem Nemri , Hani Wadie Badri , Ridha Ghayoula , Hichem Trabelsi , Ali Gharsallah
This paper is aimed at assessing the effectiveness of the phase-only control strategy based on a customized Taguchi method when applied to Uniform Circular Arrays (UCA).  The objective of this paper consists to contribute the main lobe optimization of the smart antenna using Taguchi's method. We used the cited method in order to determine phase's weights for each element of the circular antenna array in order to steer the principal lobe from -65° to 65° covering all angular space. After that, we made an electronic platform using the microcontroller STM8S in order to implement an intelligent system. The architecture of this work had used a digital phase shifters, a demodulator AD8347, a modulator AD8349, an array antenna, cards STM8S-Discovery.
Volume: 6
Issue: 3
Page: 1077-1085
Publish at: 2016-06-01

A Numerical Model of Joule Heating in Piezoresistive Pressure Sensors

10.11591/ijece.v6i3.pp1223-1232
Abdelaziz Beddiaf , Fouad Kerrour , Salah Kemouche
Thermal drift caused by Joule heating in piezoresistive pressure sensors affects greatly the results in the shift of the offset voltage of the such sensors. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristic drift. The impact of Joule heating in a pressure sensor has been studied. The study involves the solution of  heat transfer equation considering  the conduction in Cartesian coordinates for the transient regime using Finite Difference Method. We determine how the temperature affects the sensor during the applying a supply voltage. For this, the temperature rise generated by Joule heating in piezoresistors has been calculated for  different geometrical parameters of the sensor as well as for different operating time. It is observed that Joule heating leads to important rise temperature in the piezoresistor and, hence, causes drift in the output voltage variations in a  sensor during its operated in a prolonged time. This paper put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. The optimization of geometric parameters of sensor allows us to reducing the internal heating effect. Results showed also that low bias voltage should be applied for reducing Joule heating.
Volume: 6
Issue: 3
Page: 1223-1232
Publish at: 2016-06-01

Design of Hollow-Rotor Brushless DC Motor

10.11591/ijpeds.v7.i2.pp387-396
Raja Nor Firdaus Raja Othman , Farina Sulaiman , Suhairi Rizuan , Kasrul Abdul Karim , Auzani Jidin , Tole Sutikno , Norhisam Misron
This paper discusses about design of hollow-rotor Brushless DC (BLDC) motor. A conventional BLDC motor has more leakage flux circling at the end of the permanent magnet that will limit torque. To overcome this problem, a new BLDC model known as hollow-rotor is proposed. The objective of this research is to design a hollow-rotor motor that will have higher torque density compared to conventional BLDC motor using Finite Element Method (FEM). In addition, performance analysis of the proposed hollow-rotor has also been carried out. For validation, the result of FEM is compared with the measurement result. It shows that, the simulation result has good agreement with the measurement result. For comparison, hollow-rotor shows higher torque density compared to conventional BLDC motor. As a conclusion, this paper provides guidelines and analysis in designing high torque hollow-rotor motor.
Volume: 7
Issue: 2
Page: 387-396
Publish at: 2016-06-01

Automatic Extraction Of Malay Compound Nouns Using A Hybrid Of Statistical And Machine Learning Methods

10.11591/ijece.v6i3.pp925-935
Muneer A. S. Hazaa , Nazlia Omar , Fadl Mutaher Ba-Alwi , Mohammed Albared
Identifying of compound nouns is important for a wide spectrum of applications in the field of natural language processing such as machine translation and information retrieval. Extraction of compound nouns requires deep or shallow syntactic preprocessing tools and large corpora. This paper investigates several methods for extracting Noun compounds from Malay text corpora. First, we present the empirical results of sixteen statistical association measures of Malay <N+N> compound nouns extraction. Second, we introduce the possibility of integrating multiple association measures. Third, this work also provides a standard dataset intended to provide a common platform for evaluating research on the identification compound Nouns in Malay language. The standard data set contains 7,235 unique N-N candidates, 2,970 of them are N-N compound nouns collocations. The extraction algorithms are evaluated against this reference data set. The experimental results  demonstrate that a group of association measures (T-test , Piatersky-Shapiro (PS) , C_value, FGM and  rank combination method) are the best association measure and outperforms the other association measures for <N+N> collocations in the Malay  corpus. Finally, we describe several classification methods for combining association measures scores of the basic measures, followed by their evaluation. Evaluation results show that classification algorithms significantly outperform individual association measures. Experimental results obtained are quite satisfactory in terms of the Precision, Recall and F-score.
Volume: 6
Issue: 3
Page: 925-935
Publish at: 2016-06-01

Single-Switch Soft-Switched Boost Power Factor Corrector for Modular Applications

10.11591/ijpeds.v7.i2.pp279-293
Tomas A. Gonzalez , Daniel O. Mercuri , Hernan E. Tacca , Maximo E. Pupareli
Modern dc power supplies provide power factor correction but the classical two-stage approach, using hard-switched preregulators, has detrimental effects on efficiency and reliability, particularly for high power applications. With some circuit modifications and the addition of a few magnetic components, diodes and capacitors, we have turned a classical boost power factor corrector into a high efficiency soft-switched version. The proposed converter turns on its single switch with zero current and turns it off with zero voltage. In this paper we explain the proposed changes, we study the waveforms and equations and we verify them with an experimental prototype. We also show how the converter can be used for modular single- and three-phase high power applications.
Volume: 7
Issue: 2
Page: 279-293
Publish at: 2016-06-01

Dynamic control and Resource management for Mission Critical Multi-tier Applications in Cloud Data Center

10.11591/ijece.v6i3.pp1023-1030
Choudhury Nishikanta Sahoo , Veena Goswami
The multi-tier architecture style has become an industry standard in modern data centers with each tier providing certain functionality. To avoid congestion and to adhere the SLA under fluctuating workload and unpredictable failures of Mission Critical Multi-tier applications hosted in the cloud, we need a Dynamic admission control policy, such that the requests must be processed from the first tier to the last without any delay. This paper presents the least strict admission control policy, which will induce the maximal throughput, for a two-tier system with parallel servers. We propose an optimization model to minimize the total number of virtual machines for computing resources in each tier by dynamically varying the mean service rate of the VMs. Some performance indicators and computational results showing the effect of model parameters are presented. This model is also applicable to priority as well as real-time based applications in Cloud based environment.
Volume: 6
Issue: 3
Page: 1023-1030
Publish at: 2016-06-01

A Fast and Efficient Shape Descriptor for an Advanced Weed Type Classification Approach

10.11591/ijece.v6i3.pp1168-1175
Adil Tannouche , Khalid Sbai , Miloud Rahmoune , Amine Zoubir , Rachid Agounoune , Rachid Saadani , Abdelali Rahmani
In weed management, the distinction between monocots and dicots species is an important issue. Indeed, the yield is much higher with the application of a selective treatment instead of using a broadcast herbicide overall the parcel. This article presents a fast shape descriptor designed to distinguish between these two families of weeds. The efficiency of the descriptor is evaluated by analyzing data with the pattern recognition process known as the discriminant factor analysis (DFA). Excellent results have been obtained in the differentiation between these two weed species
Volume: 6
Issue: 3
Page: 1168-1175
Publish at: 2016-06-01

The Effects of Spread-Spectrum Techniques in Mitigating Conducted EMI to LED Luminance

10.11591/ijece.v6i3.pp1332-1343
Mohammad Yanuar Hariyawan , Risanuri Hidayat , Eka Firmansyah
Rapid voltage and current changes in recently ubiquitous LED driver have a potency to interfere other devices. Solutions with special converter design, component design, EMI filter, and spread-spectrum techniques have been proposed. Due to cost-size-weight constraints, spread-spectrum technique seems a potential candidate in alleviating EMI problem in LED application. In this paper, the effectiveness of conducted EMI suppression performance of the spread-spectrum technique is evaluated. Spread-spectrum techniques applied by giving disturbance to the system LED driver with 3 profile signals, filtered square, triangular, and sine disturbance signal to the switching pattern of a buck LED driver. From the test results, 472.5 kHz triangular and 525 kHz sine signal can reduce EMI about 42 dBuV whilethe filtered square signal can reduce EMI 40.70 dBuV compare with fundamental constantfrequency reference 669 kHz. The average reduction in the power level of the third signal inthe frequency range of 199 kHz to 925 kHz for 5.154281 dBuV and the filtered square signal can reduce the average power level better than other signal disturbance of 5.852618 dBuV.LED luminance decrease when the spread-spectrum technique is applied to the system about 2814 lux.
Volume: 6
Issue: 3
Page: 1332-1343
Publish at: 2016-06-01

Genetic Algorithm Application in Asymmetrical 9-Level Inverter

10.11591/ijpeds.v7.i2.pp521-530
Rachid Taleb , M’hamed Helaimi , Djilali Benyoucef , Zinelaabidine Boudjema
Selective harmonic elimination (SHE) has been a widely researched alternative to traditional PWM techniques. This paper presents the selective harmonic elimination of a uniform step asymmetrical multilevel inverter (USAMI) using genetic algorithm (GA) which eliminates specified higher order harmonics while maintaining the required fundamental voltage. This technique can be applied to USAMI with any number of levels. As an example, in this paper a 9-level USAMI is considered and the optimum switching angles are calculated to eliminate the 5th, 7th and 11th harmonics.
Volume: 7
Issue: 2
Page: 521-530
Publish at: 2016-06-01

A Novel Optimal PI Parameter Tuning Strategy to Improve Constant Switching Performance of Direct Torque Control

10.11591/ijpeds.v7.i2.pp422-430
Sundram Ramahlingam , Auzani Jidin , Tole Sutikno
This paper presents a novel method of optimal Propotional-Intergral (PI) controller’s parameter tuning strategy in-order to improve the Constant Switching Performance of 3-phase DTC shceme. The Direct Torque Control (DTC) sheme is acknowledged to provide fast decoupled control over the torque output and stator flux via a simple control structure. However, DTC sheme has two major downsides, which are the inconsistent inverter switching frequency and high torque output ripple. The main reason that contributes to these tribulations is the usage of hysteresis comparators in order to control the output torque. The realization of PI based controller method as replacement of hyterisis controller in DTC system able to provide significant solutions to over come the fall back while retaining the simple control structure of conventional DTC. The combination usage of higher sampling controller DS1004 and also 3-level CHMI in this system can further minimize the output torque ripple by providing higher resolution with lower digital error and greater number of vectors. This paper presents detail explanation and calculation of optimal PI parameter tuning strategy consecutively to enhance the performance of 3-level DTC system. In order to verify the feasibility of the proposed method experimentation, the proposed method is compared with convention DTC system via simulation and experiment results.
Volume: 7
Issue: 2
Page: 422-430
Publish at: 2016-06-01

URL ATTACKS: Classification of URLs via Analysis and Learning

10.11591/ijece.v6i3.pp980-985
M. Rajesh , R. Abhilash , R. Praveen Kumar
Social Networks such as Twitter, Facebook play a remarkable growth in recent years. The ratio of tweets or messages in the form of URLs increases day by day. As the number of URL increases, the probability of fabrication also gets increased using their HTML content as well as by the usage of tiny URLs. It is important to classify the URLs by means of some modern techniques. Conditional redirection method is used here by which the URLs get classified and also the target page that the user needs is achieved. Learning methods also introduced to differentiate the URLs and there by the fabrication is not possible. Also the classifiers will efficiently detect the suspicious URLs using link analysis algorithm.
Volume: 6
Issue: 3
Page: 980-985
Publish at: 2016-06-01

Efficient Low-Complexity Digital Predistortion for Power Amplifier Linearization

10.11591/ijece.v6i3.pp1096-1105
Siba Monther Yousif , Roslina M. Sidek , Anwer Sabah Mekki , Nasri Sulaiman , Pooria Varahram
In this paper, a low-complexity model is proposed for linearizing power amplifiers with memory effects using the digital predistortion (DPD) technique. In the proposed model, the linear, low-order nonlinear and high-order nonlinear memory effects are computed separately to provide flexibility in controlling the model parameters so that both high performance and low model complexity can be achieved. The performance of the proposed model is assessed based on experimental measurements of a commercial class AB power amplifier by applying a single-carrier wideband code division multiple access (WCDMA) signal. The linearity performance and the model complexity of the proposed model are compared with the memory polynomial (MP) model and the DPD with single-feedback model. The experimental results show that the proposed model outperforms the latter model by 5 dB in terms of adjacent channel leakage power ratio (ACLR) with comparable complexity. Compared to MP model, the proposed model shows improved ACLR performance by 10.8 dB with a reduction in the complexity by 17% in terms of number of floating-point operations (FLOPs) and 18% in terms of number of model coefficients.
Volume: 6
Issue: 3
Page: 1096-1105
Publish at: 2016-06-01

Enhanced Torque Control and Reduced Switching Frequency in Direct Torque Control Utilizing Optimal Switching Strategy for Dual-Inverter Supplied Drive

10.11591/ijpeds.v7.i2.pp328-339
M. Khairi Rahim , Auzani Jidin , Tole Sutikno
Direct Torque Control (DTC) of induction machine has received wide acceptance in many adjustable speed drive applications due to its simplicity and high performance torque control. However, the DTC using a common two-level inverter poses two major problems such as higher switching frequency (or power loss) and larger torque ripple. These problems are due to inappropriate voltage vectors which are selected among a limited number of voltage vectors available in two-level inverter. The proposed research aims to formulate an optimal switching strategy using Dual-Inverter Supplied Drive for high performances of DTC. By using dual-inverter supplied, it provides greater number of voltage vectors which can offer more options to select the most appropriate voltage vectors. The most appropriate voltage vectors should able to produce minimum torque slope but sufficient to satisfy torque demands. The identification is accomplished by using an equation of rate of change of torque which is derived from the induction machine equations. The proposed strategy also introduces a block of modification of torque error status which is responsible to modify the status such that it can determine the most optimal voltage vectors from a look-up table, according to motor operating conditions. The improvements obtained are as follows; 1) minimization of switching frequency (reduce power loss), and 2) reduction of torque ripple. Some improvements obtained in the proposed strategy were verified via experimentations.
Volume: 7
Issue: 2
Page: 328-339
Publish at: 2016-06-01

Analysis and Implementation of a High Boost Ratio DC-DC Converter for Minimizing Commutation Torque Ripple in Brushless DC Motor

10.11591/ijpeds.v7.i2.pp583-600
M. Senthil Raja , B. Geethalakshmi
Brushless dc motor still suffers from commutation torque ripple, which primarily depends on transient line current in the commutation interval. In order to control the incoming and outgoing phase currents to change at the same rate during commutation, this paper presents a novel high boost ratio DC-DC circuit topology in the front end of the inverter. With a suitable closed loop control scheme, the proposed high boost ratio DC-DC converter is operated with two different duty ratios one during commutation period and the other during non commutation period. The cause of commutation ripple is analyzed, and the way to adjust the duty ratio for obtaining the desired dc link voltage is introduced in detail. Finally, simulation and experimental results show that, compared with the existing dc–dc converter topologies, the proposed method can obtain the desired voltage much faster and minimize commutation torque ripple more efficiently
Volume: 7
Issue: 2
Page: 583-600
Publish at: 2016-06-01
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