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Ohrid, Macedonia

The University for Information Science and Technology "St. Paul The Apostole" , is a state university located in Ohrid, Macedonia. Founded in 2009, the university is organized in 6 Faculties. The University is an international University where you can find not only students but also professors from abroad of Macedonia, therefore the lectures are held in English. Wikipedia.

Chang T.P.,University for Information Science and Technology
Energy Conversion and Management | Year: 2011

In this paper, wind energy in Taiwan is assessed according to Weibull function. The heuristic searching technique, particle swarm optimization (PSO), is applied originally to find the Weibull parameters. Wind data used is measured by three wind turbines located at different climate regions, i.e. Dayuan, Hengchun and Penghu. The results show that the PSO is powerful in searching parameters. Three stations experiencing stronger northeastern monsoon have more power density in winter. Yearly wind speed distribution in Hengchun matches best with the Weibull function. Weibull shape parameters lie between 2 and 3; scale parameters reveal similar trends with mean speeds by 12% greater. On the basis of Weibull distribution, the order of magnitude is always in speed carrying maximum energy, scale parameter, mean speed and most probable speed for all the stations. There is much room to enhance turbine's conversion efficiency especially in Penghu according to the analyses of availability and capacity factors. The wind in inland stations could relatively provide more energy near noon. Wind power density presents inverse change with solar irradiance over the year. © 2010 Elsevier Ltd. All rights reserved. Source

Iwata Y.,University for Information Science and Technology | Oka K.,Tokyo University of Information Sciences | Yoshida Y.,Preferred Infrastructure
Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms | Year: 2014

In the area of parameterized complexity, to cope with NP- Hard problems, we introduce a parameter k besides the input size n, and we aim to design algorithms (called FPT algorithms) that run in 0(f(k)nd) time for some function f(k) and constant d. Though FPT algorithms have been successfully designed for many problems, typically they are not sufficiently fast because of huge f(k) and d. In this paper, we give FPT algorithms with small f(k) and d for many important problems including Odd Cycle Transversal and Almost 2-SAT. More specifically, we can choose f(k) as a single exponential (4k) and d as one, that is, linear in the input size. To the best of our knowledge, our algorithms achieve linear time complexity for the first time for these problems. To obtain our algorithms for these problems, we consider a large class of integer programs, called BIP2. Then we show that, in linear time, we can reduce BIP2 to Vertex Cover Above LP preserving the parameter k, and we can compute an optimal LP solution for Vertex Cover Above LP using network flow. Then, we perform an exaustive search by fixing half- integral values in the optimal LP solution for Vertex Cover Above LP. A bottleneck here is that we need to recompute an LP optimal solution after branching. To address this issue, we exploit network flow to update the optimal LP solution in linear time. Copyright © 2014 by the Society for Industrial and Applied Mathematics. Source

Chang T.P.,University for Information Science and Technology
Applied Energy | Year: 2011

In addition to the probability density function (pdf) derived with maximum entropy principle (MEP), several kinds of mixture probability functions have already been applied to estimate wind energy potential in scientific literature, such as the bimodal Weibull function (WW) and truncated Normal Weibull function (NW). In this paper, two other mixture functions are proposed for the first time to wind energy field, i.e. the mixture Gamma-Weibull function (GW) and mixture truncated normal function (NN). These five functions will be reviewed and compared together with conventional Weibull function. Wind speed data measured from 2006 to 2008 at three wind farms experiencing different climatic environments in Taiwan are selected as sample data to test their performance. Judgment criteria include four kinds of statistical errors, i.e. the max error in Kolmogorov-Smirnov test, root mean square error, Chi-square error and relative error of wind potential energy. The results show that all the mixture functions and the maximum entropy function describe wind characterizations better than the conventional Weibull function if wind regime presents two humps on it, irrespective of wind speed and power density. For wind speed distributions, the proposed GW pdf describes best according to the Kolmogorov-Smirnov test followed by the NW and WW pdfs, while the NN pdf performs worst. As for wind power density, the MEP and GW pdfs perform best followed by the WW and NW pdfs. The GW pdf could be a useful alternative to the conventional Weibull function in estimating wind energy potential. © 2010 Elsevier Ltd. Source

Ahmed A.,University for Information Science and Technology | Boulahia L.M.,CNRS Risk Management Science and Technology | Gaiti D.,CNRS Risk Management Science and Technology
IEEE Communications Surveys and Tutorials | Year: 2014

Wireless networks are passing through a transition phase for the past few years now and this transition is giving a way towards the convergence of all IP-based networks to form the Next Generation Networks (NGNs). With the proliferation of these networks in daily life, users' needs are also increasing and service operators are offering different services to satisfy their customers for a better grade of service and an elevated quality of experience (QoE). However, a single operator cannot fulfill the huge demands of the users especially, if a user is nomadic. In nomadism, a user traverses number of available networks that might contain cellular or wireless data networks, usually known as heterogeneous wireless networks. These networks offer various services from email to live video streaming depending upon their capacity and nature. During this traversing procedure, a user switches among different networks to satisfy his/her needs in terms of quality of service. This process is commonly known as a vertical handover or handoff (VHO) due to the involvement of heterogeneous wireless networks in it. An extensive work has been carried out in this field in order to fulfill user demands for better QoS and QoE. In this paper, we give a detailed state-of-the-art of these existing vertical handover decision mechanisms that aim at providing ubiquitous connectivity to the mobile users. We have categorized these vertical handover measurement and decision schemes on the basis of their employed techniques and parameters. Also, we present a comprehensive summary of their advantages and drawbacks. This paper gives its readers an overview of the active research initiatives in the area of handover decision making process in heterogeneous wireless networks and identifies the challenges behind the seamless services provisioning during mobility. © 2014 IEEE. Source

Rao R.S.,Jawaharlal Nehru Technological University Anantapur | Ravindra K.,Jawaharlal Nehru Technological University Anantapur | Satish K.,Jawaharlal Nehru Technological University Anantapur | Narasimham S.V.L.,University for Information Science and Technology
IEEE Transactions on Power Systems | Year: 2013

This paper presents a new method to solve the network reconfiguration problem in the presence of distributed generation (DG) with an objective of minimizing real power loss and improving voltage profile in distribution system. A meta heuristic Harmony Search Algorithm (HSA) is used to simultaneously reconfigure and identify the optimal locations for installation of DG units in a distribution network. Sensitivity analysis is used to identify optimal locations for installation of DG units. Different scenarios of DG placement and reconfiguration of network are considered to study the performance of the proposed method. The constraints of voltage and branch current carrying capacity are included in the evaluation of the objective function. The method has been tested on 33-bus and 69-bus radial distribution systems at three different load levels to demonstrate the performance and effectiveness of the proposed method. The results obtained are encouraging. © 2012 IEEE. Source

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