Journal of Advanced Engineering and Computation
Call for paper - September - 2018 (Jul 20, 2018) More...
This paper presents two methods for on-line computation of dynamic fault location in HV transmission lines using three means; resistance, reactance and impedance. These methods can be used for dynamic distance protection of the transmission line. The Gilchrist method and McInnes method are presented. The proposed methods use digital set of short circuit current and voltage measurements for estimating fault location. A practical case study is presented in this work to evaluate the proposed methods. A study is done to evaluate the best mean to locate the fault. A comparison of these two methods is presented. MATLAB-Simulink software was used to do all the tests. Results are reported and conclusions are drawn.
In this paper, a variable step size P&O algorithm is used in order to improve the performance of a photovoltaic system in both dynamic and static plans. The efficiency of the proposed algorithm has been investigated successfully using the BP SX150S solar module connected to the DC-DC derived by a P&O MPPT algorithm. The comparative study results of both conventional fixed step size and the proposed variable step size P&O algorithms prove the effectiveness of the proposed algorithm compared to the standard fixed step size PO MPPT. The proposed algorithm reduces response time between 13.86% and 45.28% and the steady state oscillation between 83.33% and 100% leading to less power loss especially in case of fast changing atmospheric conditions.
After the absorption of the photons, during the photovoltaic conversion process, one part of the radiation remains unabsorbed causing the cell to overheat and thus a drop in efficiency. The purpose of this study is to explore the effect of junction temperature, geographic coordinates as well as the season on the electrical performance of the photovoltaic cell. The results obtained show that the junction temperature has an effect which is not favorable on the electrical efficiency of the module for high temperatures around midday which is of 11% however it reaches 14% for low temperatures in the morning. Geographical coordinates at different altitudes, have no effect on the energy produced from the module, but the effect of the season on the efficiency confirms the previous results, that, the efficiency is good for low temperatures. The results are obtained by simulation, through a computer code in FORTRAN language, designed for this purpose.
Along with the rapid development of science and technology in today's society, lighting technology, especially white light-emitting diodes (WLEDs), has become a critical and essential element in almost every field of our daily life. Therefore, the enhancement of luminous efficiency has become an important objective in the production of white LEDs to serve the needs of customers. This paper presents the influence of Ca2MgSi2O7:Eu2+ green luminescent phosphor on the light quality of WLEDs. In this work, the green-emitting
Ca2MgSi2O7:Eu2+ phosphor is added into the in-cup phosphor configuration, which leads to the varying of the scattering property of this compounding. This is proved through the scattering coefficient from Mie-theory. Besides, the color quality scale which is called CQS index of WLEDs is also verified. The achieved results indicate that the luminous efficacy increases significantly if the Ca2MgSi2O7:Eu2+ concentration is varied. The smaller the Ca2MgSi2O7:Eu2+ size is used, the higher the luminous flux is obtained. However, the CQS can decrease if Ca2MgSi2O7:Eu2+ concentration is adjusted in another direction. Therefore, it is vital to select a suitable concentration and size of Ca2MgSi2O7:Eu2+ for enhancing the luminous efficacy of WLEDs, and the benet of this phosphor in creating white WLED packages is a potential solution for developing LED illumination technology.
The paper describes a technique for stability analysis of proportional-integral (PI) controller in linear continuous-time interval control systems. The stability conditions of Kharitonov's theorem together with related criterions, such as Routh-Hurwitz criterion for continuous-time systems, bring out sets of polynomial inequalities. The sets are very di‑cult to solve directly, especially in case of high-order systems. Direct technique was used for stability analysis without solving polynomial inequalities. Solving polynomial equation directly makes its computing speed low. In the paper, a set theory-based technique is proposed for finding robust stability range of PI controller without solving any Kharitonov polynomials directly. Computation results confirm expected computing speed of the proposed technique.
In this paper, we propose a hybrid protocol for energy harvesting in wireless relay networks, which combines the benefits of both time-switching relaying (TSR) and power-splitting relaying (PSR), which are two main protocols for energy harvesting. In TSR, a dedicated harvesting time in each time slot is allocated for energy harvesting, while the remaining time is used for information transmission. In PSR, a portion of received power is split for energy harvesting. TSR can simplify the hardware compared to PSR, but reduce the throughput or achievable rate of the system. Specifically, we conduct a rigorous analysis to derive the closed-form formulas for performance factors of the system. We deliver the analysis results for various transmission modes: instantaneous transmission, delay-limited transmission, and delay-tolerant transmission, which are different from each other on the availability of statistical information about the channels between source and relay nodes. The results are also confirmed by Monte Carlo simulation.
With the explosion of computer science in the last decade, data banks and networks
management present a huge part of tomorrows problems. One of them is the development of the best classication method possible in order to exploit the data bases. In classication problems, a representative successful method of the probabilistic model is a Naïve Bayes classier. However, the Naïve Bayes effectiveness still needs to be upgraded. Indeed, Naïve Bayes ignores misclassied instances instead of using it to become an adaptive algorithm. Different works have presented solutions on using Boosting to improve the Gaussian Naïve Bayes algorithm by combining Naïve Bayes classier and Adaboost methods. But despite these works, the Boosted Gaussian Naïve Bayes algorithm is still neglected in the resolution of classication problems. One of the reasons could be the complexity of the implementation of the algorithm compared to a standard Gaussian Naïve Bayes. We present in this paper, one approach of a suitable solution with a pseudo-algorithm that uses Boosting and Gaussian Naïve Bayes principles having the lowest possible complexity.
This paper investigates the design of decentralized controllers for a class of large scale switched nonlinear systems under arbitrary switching laws. A global large scale switched system can be split into a set of smaller interconnected switched Takagi-Sugeno fuzzy subsystems. In this context, to stabilize the overall closed-loop system, a set of switched non-Parallel-Distributed-Compensation (non-PDC) output-feedback controllers is considered. The latter is designed based on Linear Matrix Inequalities (LMI) conditions obtained from a multiple switched non-quadratic Lyapunov-like candidate function. The controllers proposed herein are synthesized to satisfy H∞ performances for disturbance attenuation. Finally, a numerical example is proposed to illustrate the effectiveness of the suggested decentralized switched controller design approach.
Enhancement of the color uniformity, the lumen output of the multi-chip white LED lamps (MCW-LEDs) at high color correlated temperature is a big challenge for researchers. However, an innovative LED lamp designed with a phosphor compounding, which combines (La,Ce,Tb) PO4:Ce:Tb (LaTb) green phosphor with YAG: CE yellow phosphor, is proposed as an optimal solution to this requirement. Index, using LaTb green phosphor into MCWLEDs could bring a superior optical performance for MCW-LEDs. It is found that the lumen output of this new MCW-LED at a high color temperature of 8500 K significantly improves up to 1600 lm compared to MCW-LEDs without LaTb phosphor. The simulation results demonstrated that the CCT deviation sharply decreases from 9000 to 1000 at the LaTb concentration range from 0 to 1.8 %, while the Color Rendering Index ability (CRI) and the Color Quality Scale (CQS) slightly decrease. To obtain the highest lumen output and the best color uniformity, the particle size range within 6 - 8 µm should be suggested.