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28,188 Article Results

Programming Learning Requirements Based on Multi Perspectives

10.11591/ijece.v7i3.pp1299-1307
Firas Layth Khaleel , Noraidah Sahari Ashaari , Tengku Siti Meriam Tengku Wook , Amirah Ismail
Students occasionally find it difficult to learn new programming languages. They often confront unfamiliar programming terms and having difficulty to visualize the processes that happen in computer memory. Weak students find this a burden and end up memorizing the processes without understanding them and their workings. This situation invariably leads students to obtain low grades in their programming subjects. The preliminary investigation of survey was produce in previous work; the results showed that students have experienced ineffective learning, lack of interest towards this course and lack of motivation. Therefore, the main objective of this study is to identify programming learning requirements based on previous work and verified from two perspectives (experts and students). Finally, the result was a group of requirements that should be considered in programming language course
Volume: 7
Issue: 3
Page: 1299-1307
Publish at: 2017-06-01

Modified Look-Up Table for Enhancement of Torque Response in Direct Torque Controlled Induction Machine

10.11591/ijpeds.v8.i2.pp522-533
Goh Wee Yen , Nik Rumzi Nik Idris , Auzani Jidin , Tole Sutikno
Basically, the direct torque control (DTC) drive system is operated at light load. At light load, supplying the drive system with rated flux will decrease the efficiency of the system. To maximize the efficiency of drive system, an optimal flux has been applied during steady-state but when a torque is suddenly needed, for example during acceleration, the dynamic of the torque response would be degraded. Therefore, a modification to the voltage vector as well as look-up table has been proposed for the torque response improvement. The proposed voltage vector is generated by adding two adjacent conventional voltage vectors and implemented by using duty ratio. The duty ratio is used to estimate the activation time of each conventional voltage vector in order to produce the proposed voltage vector.
Volume: 8
Issue: 2
Page: 522-533
Publish at: 2017-06-01

A PWM Strategies for Diode Assisted NPC-MLI to Obtain Maximum Voltage Gain for EV Application

10.11591/ijpeds.v8.i2.pp767-774
C. Bharatiraja , Shri Harish , J L Munda , P. Sanjeevikumar , M. Sriram Kumar , Vivek Bhati
The projected diode assisted Neutral Point Diode Clamed (NPC-MLI) with the photovoltaic system produces a maximum voltage gain that is comparatively higher than those of other boost conversion techniques. This paper mainly explores vector selection approach pulse-width modulation (PWM) strategies for diode-assisted NPC-MLI to obtain a maximum voltage gain without compromising in waveform quality. To obtain a high voltage gain maximum utilization of dc-link voltage and stress on the power switches must be reduced. From the above issues in the diode assisted NPC-MLI leads to vector selection approach PWM technique to perform capacitive charging in parallel and discharging in series to obtain maximum voltage gain. The operation principle and the relationship of voltage gain versus voltage boost duty ratio and switching device voltage stress versus voltage gain are theoretically investigated in detail. Owing to better performance, diode-assisted NPC-MLI is more promising and competitive topology for wide range dc/ac power conversion in a renewable energy application. Furthermore, theoretically investigated are validated via simulation and experimental results.
Volume: 8
Issue: 2
Page: 767-774
Publish at: 2017-06-01

Frequency Reconfigurable Epsilon Negative Metamaterial Antenna

10.11591/ijece.v7i3.pp1473-1479
Arrauzah Razak , M. K. A. Rahim , H. A. Majid , N. A. Murad
This paper proposes metamaterial (MTM) inspired frequency reconfigurable antenna based on thecircular electric field coupled (ELC) resonator. It is composed of circular shape ELC resonator with the radius size of 7 mm. By inserting two switches between the gaps at both side of the circular ELC resonator, it is possible to switch ON or OFF the unit cell. The antenna has been simulated using CST Microwave Studio software tool. The simulation result shows that the proposed antenna is capable of reconfiguring between two different frequencies which are2.18 GHz and 2.64 GHz. The simulated bandwidth at -10 dB is 4.12 % at resonance frequency of 2.18 GHz and 8.7% at 2.64 GHz
Volume: 7
Issue: 3
Page: 1473-1479
Publish at: 2017-06-01

Face Recognition Using Completed Local Ternary Pattern (CLTP) Texture Descriptor

10.11591/ijece.v7i3.pp1594-1601
Taha H. Rassem , Nasrin M. Makbol , Sam Yin Yee
Nowadays, face recognition becomes one of the important topics in the computer vision and image processing area. This is due to its importance where can be used in many applications. The main key in the face recognition is how to extract distinguishable features from the image to perform high recognition accuracy.  Local binary pattern (LBP) and many of its variants used as texture features in many of face recognition systems. Although LBP performed well in many fields, it is sensitive to noise, and different patterns of LBP may classify into the same class that reduces its discriminating property. Completed Local Ternary Pattern (CLTP) is one of the new proposed texture features to overcome the drawbacks of the LBP. The CLTP outperformed LBP and some of its variants in many fields such as texture, scene, and event image classification.  In this study, we study and investigate the performance of CLTP operator for face recognition task. The Japanese Female Facial Expression (JAFFE), and FEI face databases are used in the experiments. In the experimental results, CLTP outperformed some previous texture descriptors and achieves higher classification rate for face recognition task which has reached up 99.38% and 85.22% in JAFFE and FEI, respectively.
Volume: 7
Issue: 3
Page: 1594-1601
Publish at: 2017-06-01

Buck Converter Control for Lead Acid Battery Charger using Peak Current Mode

10.11591/ijpeds.v8.i2.pp686-694
Asep Nugroho , Estiko Rijanto , Latif Rozaqi
DC-DC buck converters are used for battery chargers in many applications including renewable energy sources, inverters, electric vehicles and robots. In this paper a buck converter was built and its controller was developed using peak current control mode for current loop and phase lag for voltage loop. This paper proposes a formulation of plant disturbance due to load variation to obtain a nominal model based on small signal approach. The controller was derived analytically based on the nominal model. Experiment results show that the buck control system functions well in regulating the output voltage. During the start up without any load it can reduce input voltage from 300 V to output voltage of 133.9 V in 19.3 ms. The developed controller can maintain the output voltage under load variation from no load to sudden load of 0.26 A. When it was implemented to charge a lead acid battery string, constant current of 3.36 A was charged in the first 173 minutes followed by constant voltage of 134.7 V until the end of charging at time 483 minutes. Thus, the developed control system of lead acid battery charger works well.
Volume: 8
Issue: 2
Page: 686-694
Publish at: 2017-06-01

Risk of Transient Stability Using Rotor Trajectory Index as Severity Function

10.11591/ijeecs.v6.i3.pp591-601
Elmotaz Billa Elghali , Marayati Marsadek , Agileswari K. Ramasamy
This paper presents a new approach to determine the risk of transient stability. It describes the implementation of rotor trajectory index (RTI) to assess the severity of power systems when it is subjected to a three-phase fault. The (RTI) is proposed as an index used to represent severity of transient instability. Risk of transient stability for three-phase fault is calculated using a well-known risk formula. Risk of transient stability provides a quantitative measure to evaluate the potential loss of synchronism of a generator that takes into account the probability and consequences. RTI index is calculated based on the machines rotor angles obtained at each step of a time domain simulation. RTI is proposed as an index to show the severity of the three-phase fault towards transient stability since it allows a fast and accurate measurement of the degree of stability of the system facing a fault. The proposed technique is implemented on the IEEE 39-bus system.
Volume: 6
Issue: 3
Page: 591-601
Publish at: 2017-06-01

A Survey on Security Aspects of Server Virtualization in Cloud Computing

10.11591/ijece.v7i3.pp1326-1336
O Sri Nagesh , Tapas Kumar , Venkateswara Rao Vedula
Significant exploitation and utilization of cloud computing in industry is come with and in the identical time vulnerable by unease regarding protection of data hold by cloud computing providers. One of the penalties of moving data processing and storage off business site is that organizations have fewer controls over their infrastructure. seeing that, cloud service (CS) providers must hope that the CS provider is capable to protect their data and infrastructure from both exterior and domestic attacks. Presently however, such hope can only rely on organizational procedures stated by the CS provider and cannot be remotely verified and validated by an external party. The central distinction between cloud computing and conventional enterprise internal Information Technology services is that the proprietor and the consumer of cloud Information Technology infrastructures are separated in cloud. This transform requires a safety responsibility severance in cloud computing. Cloud service providers (CSP) should safe the services they propose and cannot surpass the customers’ authorities. Virtualization is a buildup utterance in the Information Technology world. With the assure to reduce the ever mounting infrastructure inside data centers connected to other important apprehensions such as ease of use and scalability, virtualization technology has been in advance recognition not only with IT experts yet also among administrators and executives as well. The progressively more growing rate of the approval of this technology has exposed these systems to new protection concerns which in recent history have been unnoticed or merely overlooked. This paper presents an in depth state of art gaze at  present most old server virtualization explanations, as well as a writing study on different security matters found inside this virtualization technology. These problems can be practical to all the existing virtualization technologies accessible with no spotlight on a specific answer. Nevertheless, we do susceptibility investigation of two of the mainstream recognized virtualization answers: VMware ESX and Xen. to conclude, we illustrate some clarifications on how to progress the security of online banking and electronic commerce, using virtualization.
Volume: 7
Issue: 3
Page: 1326-1336
Publish at: 2017-06-01

VLSI Design of a Fast Pipelined 8x8 Discrete Cosine Transform

10.11591/ijece.v7i3.pp1430-1435
Nurulnajah Mohd Zabidi , Ab Al-Hadi Ab Rahman
This paper presents a Very Large Scale Integrated (VLSI) design and implementation of a fixed-point 8x8 multiplierless Discrete Cosine Transform (DCT) using the ISO/IEC 23002-2 algorithm. The standard DCT algorithm, which is mainly used in image and video compression technology, consists of only adders, subtractors, and shifters, therefore making it efficient for hardware implementation. The VLSI implementation of the algorithm given in this paper further enhances the performance of the transform unit. Furthermore, circuit pipelining has been applied to the base design of the DCT, which significantly improves the performance by reducing the longest path in the non-pipeline design. The DCT has been implemented using semi-custom VLSI design methodology using the TSMC 0.13um process technology. Results show that our DCT designs can run up to around 1.7 Giga pixels/s, which is well above the timing required for real-time ultra-high definition 8K video.
Volume: 7
Issue: 3
Page: 1430-1435
Publish at: 2017-06-01

The Effect of Different Dielectric Materials in Designing High-Performance Metal-Insulator-Metal (MIM) Capacitors

10.11591/ijece.v7i3.pp1554-1561
M. A. Zulkifeli , S. N. Sabki , S. Taking , N. A. Azmi , S. S. Jamuar
A Metal-Insulator-Metal (MIM) capacitor with high capacitance, high breakdown voltage, and low leakage current is aspired so that the device can be applied in many electronic applications. The most significant factors that affect the MIM capacitor’s performance is the design and the dielectric materials used. In this study, MIM capacitors are simulated using different dielectric materials and different number of dielectric layers from two layers up to seven layers.  The effect of the different dielectric constants (k) to the performance of the MIM capacitors is also studied, whereas this work investigates the effect of using low-k and high-k dielectric materials. The dielectric materials used in this study with high-k are Al2O3 and HfO2, while the low-k dielectric materials are SiO2 and Si3N4. The results demonstrate that the dielectric materials with high-k produce the highest capacitance. Results also show that metal-Al2O3 interfaces increase the performance of the MIM capacitors. By increasing the number of dielectric layers to seven stacks, the capacitance and breakdown voltage reach its highest value at 0.39 nF and 240 V, respectively.
Volume: 7
Issue: 3
Page: 1554-1561
Publish at: 2017-06-01

Effects of Switching Frequency Modulation on Input Power Quality of Boost Power Factor Correction Converter

10.11591/ijpeds.v8.i2.pp882-899
Deniss Stepins , Jin Huang
Switching frequency modulation (SFM) as spread-spectrum technique has been used for electromagnetic interference reduction in switching power converters. In this paper, a switching-frequency-modulated boost power factor correction (PFC) converter operating in continuous conduction mode is analysed in detail in terms of its input power quality. Initially, the effect of SFM on the input current total harmonic distortion, power factor and low-frequency harmonics of the PFC converter are studied by using computer simulations. Some advices on choosing parameters of SFM are given. Then the theoretical results are verified experimentally. It is shown that, from a power quality point of view, SFM can be harmful (it can significantly worsen the power quality of the PFC converter) or almost harmless. The results depend on how properly the modulation parameters are selected.
Volume: 8
Issue: 2
Page: 882-899
Publish at: 2017-06-01

A Constant Switching Frequency DTC for PMSM Using Low Switching Losses SVM–An Experimental Result

10.11591/ijpeds.v8.i2.pp558-583
K. Chikh , A. Saad , M. Khafallah , D. Yousfi , F.Z. Tahiri , M. Hasoun
A Constant Switching Frequency Direct Torque Control (CSF-DTC) with low switching losses Space Vector modulation (SVM) for Permanent Magnet Synchronous Motor (PMSM) drive is proposed in this work. The CSF-DTC combines Field Oriented Control (FOC) and basic DTC advantages. Indeed, the proposed control strategy improves the basic DTC performances, which features low flux and torque ripples as well as a fixed switching frequency. The improved DTC ensures also a fast and robust flux and torque responses by using Integral and Proportional (IP) controllers which guaranteed a good disturbance rejection.On the other hand, a symmetrical SVM technique with low switching losses in the PWM inverter is used in order to generate the desired stator voltage vector needed to control the stator flux and the motor torque. Simulation and experimental results are presentedin this paper.These results demonstrate well the performance of the basic and proposed DTC and they show the effectiveness of the constant switching frequency direct torque control.
Volume: 8
Issue: 2
Page: 558-583
Publish at: 2017-06-01

Cascaded Symmetric Multilevel Inverter with Reduced Number of Controlled Switches

10.11591/ijpeds.v8.i2.pp795-803
Tila Muhammad , Adnan Umar Khan , Hanif Jan , Muhammad Yasir Usman , Junaid Javed , Arsalan Aslam
Multilevel inverters have become popular among high power converters for the past few years due to their high quality output waveform and low total harmonic distortions (THD). In addition, the filter size also reduces significantly to achieve a pure sine wave output. Cascaded H-Bridge topology has been recognized as the most promising among various classical topologies for multi-level inverters on the basis of its modular form and ease of design, troubleshooting, packaging and high power capabilities. However, a large number of switches are required in cascaded H-Bridge multilevel inverter that leads to larger system losses and an increase in cost. In this paper the modified cascaded topology is proposed to reduce the number of controlled switches without affecting the resolution of output waveform or the number of voltage levels. We achieved this by replacing some of the high cost controlled transistor switches with diodes, in the cascaded H-Bridges. Furthermore, equal voltage source sharing is also possible by using the proposed topology. Hence the proposed inverter is a type of cascaded multilevel inverter with reduced switches, better modular structure, low cost and high efficiency. The inverter design is validated using simulations and tested on hardware prototype.
Volume: 8
Issue: 2
Page: 795-803
Publish at: 2017-06-01

Localization of Distributed Wireless Sensor Networks using Two Sage SDP Optimization

10.11591/ijece.v7i3.pp1255-1261
Reza Shahbazian , Seyed Ali Ghorashi
A wireless sensor network (WSN) may comprise a large distributed set of low cost, low power sensing nodes. In many applications, the location of sensors is a necessity to evaluate the sensed data and it is not energy and cost efficient to equip all sensors with global positioning systems such as GPS. In this paper, we focus on the localization of sensors in a WSN by solving an optimization problem. In WSN localization, some sensors (called anchors) are aware of their location. Then, the distance measurements between sensors and anchors locations are used to localize the whole sensors in the network. WSN localization is a non-convex optimization problem, however, relaxation techniques such as semi-definite programming (SDP) are used to relax the optimization. To solve the optimization problem, all constraints should be considered simultaneously and the solution complexity order is O(n2) where n is the number of sensors. The complexity of SDP prevents solving large size problems. Therefore, it would be beneficial to reduce the problem size in large and distributed WSNs. In this paper, we propose a two stage optimization to reduce the solution time, while provide better accuracy compared with original SDP method. We first select some sensors that have the maximum connection with anchors and perform the SDP localization. Then, we select some of these sensors as virtual anchors. By adding the virtual anchors, we add more reference points and decrease the number of constraints. We propose an algorithm to select and add virtual anchors so that the total solution complexity and time decrease considerably, while improving the localization accuracy.
Volume: 7
Issue: 3
Page: 1255-1261
Publish at: 2017-06-01

Shape Based Image Retrieval using Lower Order Zernike Moments

10.11591/ijece.v7i3.pp1651-1660
G. Sucharitha , Ranjan K. Senapati
Shape is one of the significant features of Content Based Image Retrieval (CBIR). This paper proposes a strong and successful shape feature, which is based on a set of orthogonal complex moments of images known as Zernike moments. For shape classification Zernike moment (ZM) is the dominant solution. The radial polynomial of Zernike moment produces the number of concentric circles based on the order. As the order increases number of circles will increases, due to this the local information of an image will be ignored. In this paper, we introduced a novel method for radial polynomial where local information of an image given importance. We succeeded to extract the local features and shape features at very a low order of polynomial compared to the state of traditional ZM.The proposed method gives an advantage of a lower order, less complex, and lower dimension feature vector.For more similar images we find that simple  Euclidian distance approximately zero. Proposed method tested on a MPEG-7 CE-1 shape database, Coil-100 databases. Experiments demonstrated that it is outperforming in identifying the shape of an object in the image  and reduced the retrieving time and complexity of calculations.
Volume: 7
Issue: 3
Page: 1651-1660
Publish at: 2017-06-01
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