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The Injection Velocity and Apogee Simulation for Transfer Elliptical Satellite Orbits

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International Journal of Communications, Network and System Sciences 2012年第3期5卷 187-191页

作者： Shkelzen Cakaj bexhet kamo Vladi Kolici Olimpjon Shurdi Faculty of Information Technology Polytechnic University of TiranaTiranaAlbania

Basic resources for communication satellites are communication radio-frequencies and satellite orbits. An orbit is the trajectory followed by the satellite. The communication between the satellite and a ground station is established only when the satellite is consolidated in its own orbit and it is visible from the ground station. Different types of orbits are possible, each suitable for a specific application or mission. Most used orbits are circular, categorized as low, medium and geosynchronous (geostationary) orbits based on the attitude above the Earths surface. The launching process heading the satellite in geostationary orbit, by the first step places the satellite in a transfer orbit. The transfer orbit is elliptical in shape with low attitude at perigee, and the apogee of the geostationary orbit attitude. The apogee of the parking orbit depends on the injection velocity applied at perigee. Simulation approach of injection velocity at perigee to attain different apogees, considering an incremental step is presented in this paper.

关键词： Satellite Orbit Apogee Perigee Velocity

The Range and Horizon Plane Simulation for Ground Stations of Low Earth Orbiting(LEO)Satellites

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International Journal of Communications, Network and System Sciences 2011年第9期4卷 585-589页

作者： Shkelzen Cakaj bexhet kamo Vladi Kolici Olimpjon Shurdi Faculty of Information Technology Polytechnic University of TiranaAlbania

Communication via satellite begins when the satellite is positioned in the desired orbital position. Ground stations can communicate with LEO (Low Earth Orbiting) satellites only when the satellite is in their visibility region. The ground station’s ideal horizon plane is in fact the visibility region under 0o of elevation angle. Because of natural barriers or too high buildings in urban areas, practical (visible) horizon plane differs from the ideal one. The duration of the visibility and so the communication duration varies for each LEO satellite pass at the ground station, since LEO satellites move too fast over the Earth. The range between the ground station and the LEO satellite depends on maximal elevation of satellite’s path above the ground station. The dimension of the horizon plane depends on satellite’s orbital attitude. The range variations between the ground station and the satellite, and then ground station horizon plane simulation for low Earth orbiting satellites as a function of orbital attitude is presented. The range impact and horizon plane variations on communication duration between the ground station and LEO satellites are given.

关键词： LEO Satellite Range Horizon

The Availability Improvement of Uninterruptible Power Supply by Stabilizing Node Application at Control Part

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Journal of Energy and Power Engineering 2012年第12期6卷 2031-2037页

作者： bexhet kamo Shkelzen Cakaj Aleksander Biberaj Olimpjon Shurdi Sanije Cela Faculty of Information Technology Polytechnic University Tirana 1000 Albania

The UPS （uninterruptible power supplies） are essential power infrastructure components of systems designed for critical application, including data centers. High availability achievement is a very important factor related to UPS performance, consequently to proper critical application functionality. Generally, UPS have a limited input voltage window, referring to the nominal input voltage value. Goal of this paper is to prove larger voltage window, without affecting normal UPS operation. Larger window will result on less commutation, backup and normal mode reduction, and consequently duty time of batteries reduction, too. Thus, under these conditions, it is to be expected availability improvement. The stabilizing node model, applied at UPS＇s control part through this paper is presented. UPS＇s behavior with an implemented stabilizing node is observed at few sites. In order to analyze and conclude about UPS＇s performance under these technical conditions, simulation results are further presented.

关键词： Availability stabilizing node uninterruptible power supply online UPS.

Integrity Monitoring in Navigation Systems: Fault Detection and Exclusion RAIM Algorithm Implementation

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Journal of Computer and Communications 2015年第6期3卷 25-33页

作者： Alban Rakipi bexhet kamo Shkelzen Cakaj Vladi Kolici Algenti Lala Ilir Shinko Faculty of Information Technology Polytechnic University of Tirana Tirana Albania

The use of GPS is becoming increasingly popular for real-time navigation systems. To ensure that satellite failures are detected and excluded at the receiver is of high importance for the integrity of the satellite navigation system. The focus of this paper is to implement a fault detection and exclusion algorithm in a software GPS receiver in order to provide timely warnings to the user when it is not advisable to use the GPS system for navigation. The GPS system currently provides some basic integrity information to users via the navigation message, but it is not timely enough for safety-critical applications. RAIM is a means of providing integrity with the capability of detecting when a satellite failure or a measurement error has occurred. It is the simplest and most cost effective technique for integrity monitoring. After applying the iterative fault detection and the exclusion algorithm, a significant improvement in positioning accuracy is achieved.

关键词： Algorithm GPS Integrity Monitoring RAIM

An Efficient Algorithm for the Evaluate of the Electromagnetic Field near Several Radio Base Stations

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通讯和计算机（中英文版） 2013年第6期10卷 832-843页

作者： Algenti Lala Sanije Cela bexhet kamo Faculty of lnformation Technology Polytechnic University Tirana 10000 Albania

This paper is motivated by the increased presence of the radio base stations, and the need to calculate the electromagnetic field near them. The debate on the effects of the electromagnetic field exposure, in line with the increased success and presence of the mobile telephony, has attracted the public interest and it has become a concern for the community. The standard procedures in place for estimation of the electromagnetic field require prior knowledge of the criteria for the field evaluation, be it near field, far field, presence of one or several base stations, the operating frequencies bands and their combinations. Aiming to have a practical method for the evaluation, the authors will try to do develop a theoretic model, on which base the authors will simulate the antenna of the base station and prepare the numeric method that will provide the baseline for the application. They will than compare the calculations for real situations for which all know the geometrical features, with the ones calculated based on a known theoretical method also knows as method of the moments MoM, simulated with NEC-2 (numerical electromagnetic code), and further more with the values measured in the field under the same conditions as the ones for the simulated environments. The results are interpreted in order to define the efficiency of the proposed method as well as to have an idea on the simplicity, accuracy and computing capacities.

关键词：无线基站电磁场评估计算能力算法标准程序模拟基站集成电路

Estimated Peak Power Density in the Vicinity of Cellular Base Stations in Albanian Territory

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通讯和计算机（中英文版） 2011年第10期8卷 843-847页

作者： bexhet kamo Rozeta Miho Mitrushi Vladi Kolici Olimpjon Shurdi Algenti Lala Faculty of Information Technology Polytechnic University Sheshi ＂Nene Tereza＂ Nr 4 Tirana Albania

Estimation of Simultaneous Exposure to Electromagnetic Radiation of 2G and 3G Base Stations in Albania

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通讯和计算机（中英文版） 2012年第10期9卷 1142-1146页

作者： Sanije Cela Algenti Lala bexhet kamo Aleksander Biberaj Rozeta Miho Mitrushi Faculty of lnformation Technology Polytechnic University Tirana Albania

Estimation of peak power density due to simultaneous exposure of non ionizing radiation for 2G and 3G base stations and the comparison of theoretical values with exposure limits for public, offers the opportunity to know the safety distance from these antennas, when they operate simultaneously with 2G 900, 2G 1800 and 3G 2100MHz. In this paper, the authors present the results of estimates of peak power density of radiation from antennas by eliminating or not taking into consideration the waves reflected from various surfaces. This method is used to estimate the peak power density of non-ionizing radiation due to simultaneous exposure to 2G and 3G base station antennas, installed on the territory of Albania. The results obtained from estimations give us the possibility of determining the safety distance, from base stations that operate simultaneously with 2G 900, 2G 1800 and 3G 2100MHz. Estimations are performed for all the Albanian territory, in order to create a clear idea of the safety distance in the vicinity of cellular base stations due to simultaneous exposure of 2G and 3G.

关键词：阿尔巴尼亚 3G基站密度估计电磁辐射 2G 非电离辐射峰值功率基站天线