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28,188 Article Results

VHDL Implementation of Capacitor Voltage Balancing Control with Level-Shifted PWM for Modular Multilevel Converter

10.11591/ijpeds.v7.i1.pp94-106
Chuen Ling Toh , Lars Einar Norum
Power electronics converters are a key component in high voltage direct current (HVDC) power transmission. The modular multilevel converter (MMC) is one of the latest topologies to be proposed for this application. An MMC generates multilevel output voltage waveforms which reduces the harmonics contents significantly. This paper presents a VHDL implementation of the capacitor voltage balancing control and level-shifted pulse width modulation (LSPWM) for MMC. The objective is to minimize the processing time with minimum gate counts. The design details are fully described and validated experimentally. An experiment is conducted on a small scale MMC prototype with two units of power cells on each arm. The test results are enclosed and discussed.
Volume: 7
Issue: 1
Page: 94-106
Publish at: 2016-03-01

Twitter Tweet Classifier

10.11591/ijai.v5.i1.pp41-44
Ashwin V
This paper addresses the task of building a classifier that would categorise tweets in Twitter. Microblogging nowadays has become a tool of communication for Internet users. They share opinion on different aspects of life. As the popularity of the microblogging sites increases the closer we get to the era of Information Explosion.Twitter is the second most used microblogging site which handles more than 500 million tweets tweeted everyday which translates to mind boggling 5,700 tweets per second. Despite the humongous usage of twitter there isn’t any specific classifier for these tweets that are tweeted on this site. This research attempts to segregate tweets and classify them to categories like Sports, News, Entertainment, Technology, Music, TV, Meme, etc. Naïve Bayes, a machine learning algorithm is used for building a classifier which classifies the tweets when trained with the twitter corpus. With this kind of classifier the user may simply skim the tweets without going through the tedious work of skimming the newsfeed.
Volume: 5
Issue: 1
Page: 41-44
Publish at: 2016-03-01

Comparison of Various Levels of Parallel Multilevel Active Filter Using NPC Multilevel Inverter

10.11591/ijaas.v5.i1.pp21-31
Farouk Hadj Benali , Fouad Azzouz
This paper puts forward the technique of reference signal generation of the reactive instantaneous power and the technique of the SPWM control signal generation of the multilevel active filter.  A comparison between the source currents before and after filtering is made. Then a comparison between the different source currents of different multilevel active filters. The subjects of comparison are the total harmonic distortions (THD) of the source current. The obtained simulation results have proved that the filtering quality is improved when increasing the active filter levels. Simulations are carried out by PSIM program.
Volume: 5
Issue: 1
Page: 21-31
Publish at: 2016-03-01

Novel Single Phase Full Bridge Inverter Formed by Floating Capacitors

10.11591/ijpeds.v7.i1.pp193-201
Prathap Reddy Bhimireddy , Sreekanth Reddy Kondreddy , Samba Siva Reddy Beduduri
In this paper, a new single-phase bridge inverter is described which can generate a more steps of voltage levels with reduced number of switches, gate driver circuits and diodes as compare to normal multilevel inverter. Another feature of this inverter is its ability to prodeuce the voltages from a single dc-link power supply which enables back-to-back operation of converter. The proposed method with more number of levels can improve power quality, lower switching losses and produce high quality voltage waveforms. Moreover at all load power factors the proposed method can be operated.The research of the model is done by means of computer simulation with the software MATLAB/SIMULINK. This topology has very low common mode voltage variation and dv/dt stress. Also this inverter is help full for reactive power compensation.
Volume: 7
Issue: 1
Page: 193-201
Publish at: 2016-03-01

An Optimal Replenishment Policy for the EPQ Model with Permissible Delay in Payments

10.11591/ijaas.v5.i1.pp13-20
Shih-Ming Ou , Kuo-Kuang Chang
Most of the past researches on economic replenishment quantity did not consider the trade credit period. In practice, however, companies in Taiwan have shown that taking the trade credit period into account when they are making inventory decisions decreases costs substantially. The aim of this paper is to develop an inventory model that incorporates a delay in payments to minimize the total inventory-relevant cost. The optimal replenishment policy of the proposed model is identified by utilizing the global optimum conditions and non-constrained quadratic nonlinear programming. The results show that the existence of global optimal inventory cycle under the condition of total cost function is convex. Accordingly, the proposed model can assist managers in effectively addressing EPQ issue under competitive market.
Volume: 5
Issue: 1
Page: 13-20
Publish at: 2016-03-01

The Retention of Women in Science, Technology, Engineering, and Mathematics: A Framework for Persistence

10.11591/ijere.v5i1.4515
Jeffry L. White , G.H. Massiha
Women make up 47% of the total U.S. workforce, but are less represented in engineering, computer sciences, and the physical sciences. In addition, race and ethnicity are salient factors and minority women comprise fewer than 1 in 10 scientist or engineer. In this paper, a review of the literature is under taken that explores the many challenges women encounter when pursing a career in the sciences. It includes a review of the national landscape and discussion of the guiding general retention theories. Finally it proposes a conceptual framework for persistence and proffers a number of research questions designed to delve deeper into the under representation phenomenon.
Volume: 5
Issue: 1
Page: 1-8
Publish at: 2016-03-01

The Roles of Teachers’ Work Motivation and Teachers’ Job Satisfaction in the Organizational Commitment in Extraordinary Schools

10.11591/ijere.v5i1.4520
Fatwa Tentama , Dessy Pranungsari
Teachers’ work motivation and teachers’ job satisfaction are the factors influencing the organizational commitment. This research is aimed to empirically examine the roles of teachers’ work motivation and teachers’ job satisfaction in the commitment of the organization in extraordinary schools. The subjects of the research are the teachers in Extraordinary School 1 Bantul Yogyakarta. The sample was taken by employing non-randomized technique. The scales of work motivation, job satisfaction and organizational commitment are used in collecting the data. The data were analyzed by using multiple linear regression technique. The results of the research show that 1) simultaneously, teachers’ work motivation and teachers’ job satisfaction are highly significant positive correlated with organizational commitment, by reaching the score of Rx1x2v=0,621 with the probability p=0,002 (p<0,01); 2) teachers’ work motivation are highly significant correlated with the organizational commitment, by reaching the score of (rx1v))=0,614 and the probability p=0,000 (p<0,01); 3) teachers’ job satisfaction is highly significant positive correlated with organizational commitment, by reaching the score of (rx2v))=0,570 and probability p=0,001 (p<0,01). Teachers’ job motivation more dominantly influence organizational commitment compared to teachers’ job satisfaction
Volume: 5
Issue: 1
Page: 39-45
Publish at: 2016-03-01

An Experimental Study of the Unbalance Compensation by Voltage Source Inverter Based STATCOM

10.11591/ijpeds.v7.i1.pp45-55
Anas Benslimane , Jamal Bouchnaif , Mohamed Azizi , Khalid Grari
This work presents an experimental study of the unbalance compensation caused by the high speed railway substations in the high-voltage power grid with a shunt voltage source inverter based STATCOM. This experimental study is realized on a reduced scale prototype. The Control of inverter is implemented in a DSP card. The practical results presented in this paper are shown the performance of unbalance compensation by VSI_STATCOM in static and dynamic regime.
Volume: 7
Issue: 1
Page: 45-55
Publish at: 2016-03-01

The Potential Impact of Online/Distance Education for Students with Disabilities in Higher Education: Results from a Meta-Analytic Investigation and Existing Research

10.11591/ijere.v5i1.4525
Matthew J. Erickson , Karen H. Larwin
The current investigation sought to understand if online and distance course offerings were providing a needed bridge to a post-secondary degree for students with disabilities.  The results of this investigation suggest that there is an absence of empirical research on this topic in the existing published research.  Results presented include findings from the K-12 data examining this impact, and the results from federal investigations on the prevalence of individuals with disabilities attending post-secondary institutions.  
Volume: 5
Issue: 1
Page: 76-81
Publish at: 2016-03-01

The Correlation between Sex, Age, Educational Background, and Hours of Service on Vigilance Level of ATC Officers in Air Nav Surabaya, Indonesia

10.11591/ijere.v5i1.4516
Lalu Muhammad Saleh , Tjipto Suwandi , Hamidah Hamidah
The vigilance of an Air Traffic Control (ATC) officer determines aviation safety. The number of aviation accidents tends to be increasing in recent years. Aviation accidents may be caused by human errors (i.e. errors made by pilot or ATC officer) or unsafe work condition. Sex, age, educational background, and hours of service might affect vigilance level of an ATC officer. This study was conducted to analyze the effect of sex, age, educational background and hours of service on ATC officers in Air Nav Surabaya vigilance level. This study applied cross-sectional study design with the number of samples was 41 staffs at Air Nav Surabaya. The obtained data were analyzed by using chi-square test. The results of data analysis indicated that sex, age, and educational background variables did not significantly affect vigilance level of ATC officers in Air Nav Surabaya as indicated by chi-square values of sex variable (p= 0.790), age variable (p= 0.241), and educational background variable (p= 0.335). Meanwhile, hours of service variable significantly affected ATC officer vigilance level as indicated by chi-square value (p) as much as 0.035. Based on these findings, it can be concluded that sex, age, and educational background variables did not correlate with ATC officers’ vigilance level while hours of service variable significantly correlated with ATC officers’ vigilance level.
Volume: 5
Issue: 1
Page: 9-13
Publish at: 2016-03-01

Technical and Economic Evaluation of Hybrid wind/PV/Battery Systems for Off-Grid Areas using HOMER Software

10.11591/ijpeds.v7.i1.pp134-143
Alireza Gheiratmand , Reza Effatnejad , Mahdi Hedayati
Incremental consumption of electrical energy, reduction of fossil fuel resources and environmental pollution problems caused by them are the main reasons, which tend the managers and officials in countries energy sector to develop use of renewable systems. In the not-too-distant future the use of renewable energy such as wind and solar will be very important and will play predominant role in economic indices of power systems. In recent years, technological advances in renewable energy and increasing price of petroleum products promote system managers to use low-cost and low-emission energy resources in form of hybrid systems and widespread propagation of electricity generation have been developed in remote areas. In Hybrid systems two or more sources of renewable energy is typically adopted, which increases the reliability of these systems. In this paper, the technical and economical consideration of a wind and solar hybrid system to supply electrical energy for a number of remote users (aid and medical emergency Shelter in Yazd) is provided. In order to investigate optimization and economic analysis of the proposed hybrid system, the HOMER software is used.  The results of Simulation in HOMER software show that Solar cells and wind systems with average generation power of 896 kWh/yr. and 343 kWh/yr., consist proportion of 72 and 28 percent of the total generated energy respectively, which are dedicated to satisfy the loads
Volume: 7
Issue: 1
Page: 134-143
Publish at: 2016-03-01

Formulating Employability Skills for Graduates of Public Health Study Program

10.11591/ijere.v5i1.4518
Nurul Qomariyah , Titi Savitri , Tridjoko Hadianto , Mora Claramita
Employability skills as non technical skills are important for effective and successful individual participation in the workplace. The main aims of the research were to identify important employability skills needed by graduates of Public Health Study Program Universitas Ahmad Dahlan (PHSP UAD) and to assess the achievement of the employability skills development that has been carried out by PHSP UAD. This study used a mixed method research with convergent design. Quantitative research was conducted with survey to graduates. Qualitative research was conducted with structured interviews to employers. Both data were analyzed separately and interpreted concurrently. Graduates and employers of PHSP UAD in broad outline were in line on the important employability skills needed in the workplace and the assessment of the achievement. Several employability skills consistently were considered important. The achievement of employability skills that were related to public health knowledge and its application was high, meanwhile the achievement of several important employability skills which are needed in the work place in the 21st were low. Employability skills needed for graduates of PHSP UAD were formulated. Curriculum revision is recommended to integrate employability skills into core activities to promote the development of employability skills of PHSP UAD graduates. 
Volume: 5
Issue: 1
Page: 22-31
Publish at: 2016-03-01

Augmented Diffuser for Horizontal Axis Marine Current Turbine

10.11591/ijpeds.v7.i1.pp235-245
Aly Hassan Elbatran , Omar Yaakob , Yasser Ahmed , Firdaus Abdallah
The potential of renewable energy sources is enormous as they can make a major contribution to the future of energy needs. The ocean has a great potential to become a practical and predictable energy source compared to other energy resources such as solar, wind, and nuclear. It offers different sources of energy which can be utilized namely wave, tidal, offshore wind, thermal, and tidal current. Among these sources, marine tidal current has major advantages such as higher power availability and predictability. The main objective of this research work is to design and develop a horizontal axis marine current turbine (HAMCT) that suitable for operating within Malaysian ocean, which has low speed current (0.5 – 1 m/s average). A prototype of augmented diffuser 4-bladed HAMCT applying NACA 0014 was proposed in the current study. The turbine model has 0.666 m diameter, and it was designed to produce as much as power from flowing water current. Model was constructed and tested at Marine Technology Center (MTC) in three conditions, namely, free tow testing, ducted tow testing, and ducted diffuser tow testing in order to predict the power and efficiency of the turbine system. The results showed that the application of duct was significant to concentrate the flow and diffuser arrangement was effective when it was placed behind of the rotor in this condition of low water current speed. The maximum efficiency Cp obtained in the current system was 0.58.
Volume: 7
Issue: 1
Page: 235-245
Publish at: 2016-03-01

Development of Web-Based Learning Application for Generation Z

10.11591/ijere.v5i1.4523
Bambang Hariadi , M.J. Dewiyani Sunarto , Pantjawati Sudarmaningtyas
This study aims to develop a web-based learning application as a form of learning revolution. The form of learning revolution includes the provision of unlimited teaching materials, real time class organization, and is not limited by time or place. The implementation of this application is in the form of hybrid learning by using Google Apps for Education (GAfE), called Brilian. Steps being taken in the study are: (1) requirements analysis, (2) interface design, (3) construction performance, and (4) testing and implementation. The subjects of this study were students of class 2014 and course lecturers for the student of class 2014. After the system testing that was conducted in the second semester of 2014, the collected data suggest that out of 1153 students who used this application, 79% of them were comfortable in using it. As for the lecturers, the data was obtained from 70 lecturers, 82% of them stated that this application helped their teaching process. From the evaluation results, it requires universities to further improve the network infrastructure, and applications must be developed to be more user friendly, including access to mobile learning.
Volume: 5
Issue: 1
Page: 60-68
Publish at: 2016-03-01

A New 6 DOF Robotic Arm with Linkage Motion Mechanism and Actuators Placed in Base

10.11591/ijra.v5i1.pp35-48
Mohsen Shahhosseini , Rambod Rastegari , Roozbeh Abbasi
We examined mechanism design and kinematic simulation of a new six degrees of freedom (DOF) robotic arm with rotational joints and a linkage motion mechanism. In the design, a parallel linkage mechanism, accompanied by an additional set of bevel gears, was used to create the desired motion for all six links along with transfer of all actuators to the robot’s base to reduce the mass of most of the arms. These changes resulted in reduction of the torque required for joints 1, 2, and 3. Using this parallel mechanism ensures dependence to motion links and creates a special case for the control of the robot and more rigidity against unwanted movement. Initially, we examined mechanism design methods for a parallel linkage mechanism and considered methods for application in an operational robot. In the next step, we determined the kinematic relationships that were established between the robot’s actuators and joints spaces due to the use of this mechanism. Then, we developed an example of the robot’s function in a performance simulation. The simulation results indicated that the mechanism and controller performance were acceptable.
Volume: 5
Issue: 1
Page: 35-48
Publish at: 2016-03-01
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