In this paper, a functional structure of a wind energy conversion system is introduced, before making a comparison between the two typical wind turbine operating schemes in operation, namely constant-speed wind turbine and variable-speed wind turbine. In addition, the modeling and dynamic behavior of a variable speed wind turbine with pitch control capability is explained in detail and the turbine performance curves are simulated in the MATLAB/simulink. Keywords: Drives, energy conversion, modeling, power systems, turbines, wind energy, velocity control.

The application of four algorithms (GA, PSO, SA, FA) in parameters design of a singlephase induction motor is proposed in this paper. The Four algorithms consider the motor efficiency as an objective function and with five equality and five inequality constraints. Under efficiency as an objective function the performance of the algorithm improved in the order 19.7%, 15.3%, 15.22% and 15.2% as follows, GA, SA, FA and PSO respectively, this means that for the choice of algorithm in terms of efficiency as an objective function GA is preferred. The most performed algorithm is the GA for the single phase induction motor, a code has been provided under MATLAB software. The results show that the GA method gives more suitable design optimization against conventional methods. Keywords—Design Optimization; Single Phase Induction Motor (SPIM); Maximum Efficiency; Genetic Algorithm (GA)

There is a growing interest in the deployment of off-grid renewable energy, especially for remote oil and gas facilities. This work is a novel attempt to optimally size a renewable energy system to power artificial lift for an oil well. It proposes a low-cost alternative to the abandonment and decommissioning of old wells. Sucker-rod pump artificial lift simulators (QRodTM and PROSPERTM) are deployed to estimate the energy requirement of a well, with both intermittent and continuous pumping considerations. Simulation and optimization are performed using HOMER optimized TM, which produces different system configurations and presents the possible configurations in order of increasing system costs. Based on economic and technical merits, continuous pumping using a hybrid renewable energy system consisting of solar, wind, and battery storage is chosen as the most feasible solution with 0 kWh/yr of unmet load, capacity storage of 0.56 kWh/yr, the net present cost of 145,150.50, Levelized cost of energy of 0.51/kWh and an operating cost of $3,056.04/yr. The optimal configuration is finally examined to determine its sensitivity to variation in daily solar radiation and average wind speed. It is demonstrated to be the most preferred system design, even at the least daily average solar radiation.

Reciprocating piston artificial lift systems are widely adopted especially, for onshore wells. Matching the pump mode to well and reservoir conditions reduces the pumping cost and increases the efficiency of production. Parameters influencing the energy requirement of sucker-rod lifted oil wells are investigated in this study, and new insights are provided for the parametric investigation of design variables required for sizing beam-pumped wells. Two (2) artificial lift simulators are integrated for automated sizing of beam-pumped systems. A sucker-rod artificial lift system is optimally sized for a case study oil well, to obtain the minimum API rating of the pumping unit, sustain the target production rate, and determine the corresponding minimum prime mover required to drive the pump sustainably. Compared to using a single simulator for the case study, the integrated approach reduces the damped and polished rod horsepower by 54.9% and 26.5% respectively, for a corresponding decrease in minimum NEMA D motor size by 38.6%. These key performance indicators demonstrate the benefits of simulator integration in automated sizing of beam pumps.

Reciprocating piston artificial lift systems are widely adopted especially, for onshore wells. Matching the pump mode to well and reservoir condition reduces the pumping cost and increases the efficiency of production. Parameters influencing the energy requirement of sucker-rod lifted oil wells Reciprocating piston artificial lift systems are widely adopted especially, for onshore wells. Matching the pump mode to well and reservoir condition reduces the pumping cost and increases the efficiency of production. Parameters influencing the energy requirement of sucker-rod lifted oil wells are investigated in this study, and new insights are provided for parametric investigation of design variables required for sizing beam pumped wells. Two (2) artificial lift simulators are integrated for automated sizing of beam pumped systems. A sucker-rod artificial lift system is optimally sized for a case study oil well, to obtain minimum API rating of the pumping unit, sustain the target productio...

The increase of the base transceiver station (BTS) in most urban areas can be traced to the drive by network providers to meet demand for coverage and capacity. In traditional network planning, the final decision of BTS placement is taken by a team of radio planners, this decision is not fool proof against regulatory requirements. In this paper, an intelligent based algorithm for optimal BTS site placement has been proposed. The proposed technique takes into consideration neighbour and regulation considerations objectively while determining cell site. The application will lead to a quantitatively unbiased evaluated decision making process in BTS placement. An experimental data of a 2km by 3km territory was simulated for testing the new algorithm, results obtained show a 100% performance of the neighbour constrained algorithm in BTS placement optimization. Results on the application of GA with neighbourhood constraint indicate that the choices of location can be unbiased and optimization of facility placement for network design can be carried out.

The rapid growth of the mobile telecommunication sectors of many emerging countries creates a number of problems such as network congestion and poor service delivery for network operators. This results primarily from the lack of a reliable and costeffective power solution within such regions. This study presents a comprehensive review of the underlying principles of the renewable energy technology (RET) with the objective of ensuring a reliable and cost-effective energy solution for a sustainable development in the emerging world. The grid-connected hybrid renewable energy system incorporating a power conversion and battery storage unit has been proposed based on the availability, dynamism, and technoeconomic viability of energy resources within the region. The proposed system's performance validation applied a simulation model developed in MATLAB, using a practical load data for different locations with varying climatic conditions in Nigeria. Results indicate that, apart from being environmentally friendly, the increase in the overall energy throughput of about 4 kWh/$ of the proposed system would not only improve the quality of mobile services, by making the operations of GSM base stations more reliable and cost effective, but also better the living standards of the host communities.

The rapid growth of the mobile telecommunication sectors of many emerging countries creates a number of problems such as network congestion and poor service delivery for network operators. This results primarily from the lack of a reliable and costeffective power solution within such regions. This study presents a comprehensive review of the underlying principles of the renewable energy technology (RET) with the objective of ensuring a reliable and cost-effective energy solution for a sustainable development in the emerging world. The grid-connected hybrid renewable energy system incorporating a power conversion and battery storage unit has been proposed based on the availability, dynamism, and technoeconomic viability of energy resources within the region. The proposed system's performance validation applied a simulation model developed in MATLAB, using a practical load data for different locations with varying climatic conditions in Nigeria. Results indicate that, apart from being environmentally friendly, the increase in the overall energy throughput of about 4 kWh/$ of the proposed system would not only improve the quality of mobile services, by making the operations of GSM base stations more reliable and cost effective, but also better the living standards of the host communities.

h i g h l i g h t s This study develops the optimum control model for HGES. Applies genetic-algorithm for optimal techno-economic sizing of system's components. Determine viability of proposed HGES in terms of the system's energy throughput. Implementation of proposed HGES gives an average throughput of over 12 kWh US$ À1 .

The need to compress digitised signals like speech for more efficient transmission and storage while still maintaining considerable amount of information that they convey is highly desirable. A very popular method used for compression is Linear Prediction Coding (LPC), by using the Linear Prediction Model. The development of simple fixed linear prediction filters for speech signal compression is therefore carried out in this work. The prediction filters-an analysis filter on one side and a reconstruction filter on the other are designed to have 11 fixed coefficients each. The Levinson-Durbin algorithm, derived from the Linear Prediction Model of speech is used to calculate the coefficients of the filter. Various speech signals are used to test the performance of both filters within a DPCM system. The output signals are then tested using objective and subjective quality tests. Results from these tests presented in later sections show satisfactory filter performance.

With the embrace of cellular telecommunication in Nigeria, the sector has experienced tremendous growth in terms of users. There have also been advances in technology from 2G to 3G and even 4G networks. Irrespective of the network in use, there is a section that is yet to have an alternative which is the base transceiver station BTS of the cellular network. This paper looks at the role of the BTS location on service delivery and hence customer's satisfaction in cellular networks. A survey is carried out in five major cities in Nigeria to have a professional insight into the challenges/difficulties faced by network providers in the placement of base stations. Results from this investigation reveal topography and land use problems as major challenges to the optimal placement of base stations, hence limiting coverage optimization efforts. This study provides necessary variables for the development of a tool for optimal placement of base station in order to achieve optimized radio coverage.

The dependence of TCP downstream throughput (TCP down T) on signal to noise ratio (SNR) in an IEEE802.11b WLAN system was investigated in various environments and varieties of QoS traffic. TCP down T was measured for various SNR observed. An Infrastructure based IEEE802.11b WLAN system having networked computers on which measurement software were installed, was set up consecutively in various environments (open corridor, small offices with block walls and plaster boards and free space). Empirical models describing TCP down T against SNR for different signal ranges (all ranges of signals, strong signals only, grey signals only and weak signals only) were statistically generated and validated. As the SNR values changed from high (strong signals) through low (grey signals) to very low (weak signals), our results show a strong dependence of TCP down T on the received SNR. Our models showed lower RMS errors when compared with other similar models. We observed RMS errors of 0.6734791 Mbps, 0.472209 Mbps, 0.9111563 Mbps and 0.5764460 Mbps for general (all SNR) model, strong signals model, grey signals model and Weak signals model respectively. Our models will provide researchers and WLAN systems users with a tool to estimate the TCP downstream throughput in a real network in various environments by monitoring the received SNR.

Lack of available diffuse solar radiation data in Nigeria and the variation of commonly used estimation methods with site meteorology called for the need to evaluate models and verify their suitability based on the local environmental conditions before application for the design and development of solar energy systems. This study assesses the performance of six models for estimating the monthly average daily diffuse solar radiation over Nigeria. The models considered utilize clearness index, cloud cover, relative sunshine duration or a combination of these parameters as input, for estimating diffuse solar radiations on a horizontal surface. The performance evaluation of estimation models used data sets for 37 cities with varying meteorology, which spread across the six geopolitical zones in Nigeria, for a period of 22-years. The applicability of considered methods of estimation was determined based on the coefficient of correlation, coefficient of determination, mean bias error, roo...

This paper is focused on traffic modeling in Mobile Communication networks. This research is aimed at developing a traffic models that will predict a blocking probability for voice calls and handover calls blocking probability in mobile communication networks (GSM). The high number of block calls experience in mobile network, especially during the Busy Hour (BH) has leads to poor Quality of Service (QOS) delivering in mobile network. These block calls experience in mobile network should be reduced to a certain low values (2% value in line with NCC recommended standard), to ensure good QOS. The developed traffic models are focused on new voice calls within the cell, handover calls in and out of a cell. The developed traffic models are designed based on the numbers of channels, partition into two segments in a cell network. The cell technology is homogenous in nature; therefore it is applicable to the entire mobile communication system. The analytical method is deployed, and the collection of traffic data with equipment know as the Operation and Maintenance Center (OMC-counter) which is in built in the mobile communication network is used. The OMC-counter runs on Linux operation software, which helps to capture the number of arrival calls and service time in a specified interval. The arrival rate is assumed to be Poisson and the service time is also, assumed to be exponentially distributed and independence identical distributed. These parameters are used in the development of the traffic models. The developed traffic models are blocking probability for voice calls and handover blocking probability for handover calls. These developed (propose) traffic models are validated using MATLAB (version 7.6.3. 325) program and compared with the conventional Erlang B for accuracy. These traffic models are used to manage the block calls experience in the mobile network. Also used in a balance relationship between cost incurred in mobile communication by operators and service render to the mobile communication subscribers.

This research work is aimed at the study of arrival rate and holding time used in mobile communication networks, also to determine the best suitable statistical probability distribution of both arrival rate and holding time or service time in mobile communication network. The most general acceptable assumption about arrival rate is Poisson distribution and the holding time is exponential distribution in traffic modeling of mobile communication networks. Exhaustive literature review is deployed for details explanation on discrete random variables of arrival rate and continuous holding time use in traffic modeling of mobile communication networks. From the research work, the arrival rate is explained using point process or counting process, which leads to two unique properties, they are orderly and memorylessness. These unique properties are possessed by Bernoulli process with is discrete time, having Geometric distribution function, also with Poisson process, which is continuous time and discrete space, having Exponential distribution function which is used to characterize arrival rate based on interarrival rate process. Therefore, from the research work, it is assumed that arrivals rate is Poisson distribution and service time or holding time is exponentially distributed in traffic situation in mobile communication networks. These statistical properties since to the best suitable in mobile communication networks because of their unique parameters and are simple to analyses.

This paper presents our study on the dependence of TCP downstream throughput (TCP down T) on signal to noise ratio (SNR) for multiple users in an IEEE 802.11b Wireless Local Area Network (WLAN) system. The study was carried out in small offices, open corridors and free space environments using an infrastructure based IEEE 802.11b WLAN while transmitting different quality of service (QoS) traffic all corresponding to different wireless multimedia tags. Models describing TCP down T against SNR for different signal categories were statistically generated and validated. Our findings show a large variation in the throughput behaviour of the IEEE 802.11b WLAN system for the different categories of signals. We observed RMS errors of 0.938012 Mbps, 1.047012 Mbps, 0.65833 Mbps and 0.452927 Mbps for the general (all SNR) model, strong signals model, grey signals model and weak signals model respectively which were much lower than that of similar models with which they were compared. Comparing our results with a previous work on TCP upstream throughput showed that it is more accurate to investigate upstream and downstream throughput separately. Our models enable network designers and installers to predict the TCP down T without the need to measure additional parameters other than the observed SNR which is already part of the normal network installation process.

This study assessed the performance of six solar radiation models. The objective was to determine the most accurate model for estimating global solar radiation on a horizontal surface in Nigeria. Twenty-two years meteorological data sets collected from the Nigerian Meteorological agency and the National Aeronautics and Space Administration for the three regions, covering the entire climatic zones in Nigeria were utilized for calibrating and validating the selected models for Nigeria. The accuracy and applicability of various models were determined for three locations (Abuja, Benin City, and Sokoto), which spread across Nigeria using seven viable statistical indices. This study found that the estimation results of considered models are statistically significant at the 95% confidence level, but their accuracy varies from one location to another. However, the multivariable regression relationship deduced in terms of sunshine ratio, air temperature ratio, maximum air temperature, and cloudiness performs better than other relationships. The multivariable relationship has the least root mean square error and mean absolute bias error, not exceeding 1.0854 and 0.8160 MJ m −2 day −1 , respectively, and monthly relative percentage error in the range of ± 12% for the study areas.

An empirical investigation on the dependence of TCP upstream throughput against signal to noise ratio (SNR) in an IEEE802.11b WLAN system was carried out in various environments and varieties of QoS traffic. The TCP upstream throughput (TCP up T) was measured for various SNR observed. An Infrastructure based IEEE802.11b WLAN system having networked computers on which measurement software were installed, was set up consecutively in various environments (open corridor, small offices with block walls and plaster boards and free space). Empirical models describing the TCP up T against SNR for different signals ranges (all ranges of signals, strong signals only, grey signals only and weak signals only) were statistically generated and validated. Our results show a strong dependence of TCP up T on the received SNR which varied as the SNR values changed from high (strong signals) through low (grey signals) to very low (weak signals). Our models showed lower RMS errors when compared with other similar models. We observed RMS errors of 0.5431955Mbps, 0.447938789Mbps, 1.04536603Mbps and 0.4503096Mbps for all SNR model, strong signals model, Grey signals model and Weak signals model respectively. Our models will provide researchers and WLAN systems users with a tool to estimate TCP up T in a real network in various environments by monitoring the SNR.