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27,438 Article Results

Methods of Assess the Impact of Technological Variables Complex Spatial-Distributed Systems on Costs

10.11591/ijaas.v5.i1.pp45-49
Korneev A.M. , Shmyrin A.M. , Lavrukhina T.V. , Abdullakh L.S.
The paper considers the method of calculating costs, taking into account the effect of technological parameters; the model of forecasting of costs of production resources based on the matrix of costs are described; the methods of assess the impact of parameters of complex spatial-distributed systems on costs are presented.
Volume: 5
Issue: 1
Page: 45-49
Publish at: 2016-03-01

Experimental Investigations of the Self-Controlled Synchronous Motor Connected to a Three-Phase Line Commutated SCR Inverter

10.11591/ijpeds.v7.i1.pp1-6
Tapan Kumar Chakraborty
This paper concerns the experimental investigations of the three-phase line commutated SCR inverter fed synchronous motor.  The fabricated system consists of a line-commuted inverter, a three-phase synchronous motor with the excitation winding connected in series to the inverter input, a terminal voltage sensor and a gate-pulse generating circuit. The firing pulses for SCRs of the inverter are generated by the microprocessor in proper sequence with the help of synchronizing signal derived from the terminal voltages of the synchronous machine. The steady state performance characteristics are obtained experimentally using the fabricated system. The experimental results show that a three-phase synchronous motor supplied by a line commutated inverter with the excitation winding connected in series to the dc link provide  excellent characteristics of the conventional dc series motor. 
Volume: 7
Issue: 1
Page: 1-6
Publish at: 2016-03-01

Performance Analysis of (Bi2Te3-PbTe) Hybrid Thermoelectric Generator

10.11591/ijaas.v5.i1.pp32-44
Anitha Angeline A , Jayakumar J
The performance of (Bi2Te3-PbTe) hybrid thermoelectric generator (TEG) composed of n-type Bismuth Telluride and p-type Lead Telluride semiconductor materials is presented in this paper.  The effect of different performance parameters such as output voltage, output current, output power, maximum power output, open circuit voltage, Seebeck co-efficient, electrical resistance, thermal conductance, figure of merit, efficiency, heat absorbed and heat removed based on maximum conversion and power efficiency have been theoretically analyzed by varying the hot side temperature of the hybrid thermoelectric generator up to 350oC and by varying the cold side temperature from 30oC to 150oC. The results showed that a maximum power output of 21.7 W has been obtained with the use of one hybrid thermoelectric module for a temperature difference of 320oC between the hot and cold side of the thermoelectric generator at matched load resistance. The figure of merit was found to be around 1.28 which makes its usage possible in the intermediate temperature (250oC to 350oC) applications such as heating of Biomass waste, heat from Biomass cook stoves or waste heat recovery etc. It is also observed that the hybrid thermoelectric generator offers superior performance over 250oC of the hot side temperature, compared to standard Bi2Te3 modules.
Volume: 5
Issue: 1
Page: 32-44
Publish at: 2016-03-01

Power System Design using Firefly Algorithm for Dynamic Stability Enhancement

10.11591/ijeecs.v1.i3.pp446-455
Herlambang Setiadi , Karl O Jones
Utilising additional devices in power systems have been developed by industry. Devices such as a Power System Stabilizer (PSS) and a Superconducting Magnetic Energy Storage (SMES) are commonly employed in industry. This work investigated the coordination of a PSS and SMES applied to a power system to enhance dynamic stability. To obtain optimal coordination, the parameters of the PSS and SMES are tuned using the Firefly Algorithm (FA). The simulation of the power system, PSS, and SMES has been performed using MATLAB and Simulink, and the FA run in Matlab. For testing the small signal stability, the eigenvalue of the system will be investigated, while for dynamic stability the system will be given an external disturbance. The rotor angle and frequency deviation of the power system are compared without a controller, with a PSS and SMES included, and with the PSS and SMES tuned by FA. The simulation results show that the proposed system can improve not only small signal stability (steady state stability) but also dynamic stability.
Volume: 1
Issue: 3
Page: 446-455
Publish at: 2016-03-01

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

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
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