Characteristics of Measured Rainfall Rate at Ogbomoso, Nigeria for Microwave Applications, Journal of Telecommunications and Information Technology, 2011, nr 2

Characteristics of rainfall rate useful in the estimation of attenuation due to rain are presented. Rain data collected at Ogbomoso between January–October, 2009 were used in the analysis. Result shows that power law relationship exists between the equiprobable rain rates of two different integration times. The value of conversion factor CE and CR obtained for Ogbomoso are 0.28(60) and 0.64(90) respectively. Our result then shows that different conversion factor is required for different location even within the same climatic region

EVALUATION OF SUITABLE PROPAGATION MODEL FOR 4G LTE COMMUNICATION IN NIGERIA

This paper concerns about the radio propagation models used for the 4th Generation (4G) of cellular networks known as Long Term Evolution (LTE). The radio wave propagation model or path loss model plays a very significant role in planning of any wireless communication systems. In this paper, a comparison is made between different proposed radio propagation models that would be used for LTE, like Egli model, Ecc-33 path loss model, Log- Normal Shadowing model, Lee model, Stanford University Interim (SUI) model, Cost 231 Hata Model and Experimental Measured path loss. The comparison is made using different terrains such as urban (Victoria Island, Lagos, Nigeria) and suburban (Kurudu, F.c.t. Nigeria). Egli model shows the lowest path loss in all the terrains while illustrates highest path loss in the urban area and model has highest path loss for the suburban environments.  &nbsp

PERFORMANCE EVALUATION OF AN IMPROVED ITU-R RAIN ATTENUATION PREDICTION MODEL OVER MALAYSIA EQUATORIAL REGION

Attenuation due to rainfall is one of the most fundamental constraints on the performance of satellite links above 10 GHz. This work presents the results of rain attenuation measurement using radar data collected from MMD and DIDM Malaysia. The results were compared with newly improved ITU-R P530-16 and four other selected tropical rain attenuation prediction models. The statistical analysis showed that ITU-R P 530-16 has significantly addressed the problem of rain attenuation underestimation prediction as presented by older version of the recommendatio

Modeling of rain attenuation and site diversity predictions for tropical regions

Presented in this paper is an empirical model for long-term rain attenuation prediction and statistical prediction of site diversity gain on a slant path. Rain attenuation prediction on a slant path is derived using data collected from tropical regions, and the formula proposed is based on Gaussian distribution. The proposed rain attenuation model shows a considerable reduction in prediction error in terms of standard deviation and root-mean-square (rms) error. The site diversity prediction model is derived as a function of site separation distance, frequency of operation, elevation angle and baseline orientation angle. The novelty of the model is the inclusion of low elevation angles and a high link frequency up to 70 GHz in the model derivation. The results of comparison with Hodge, Panagopoulos and Nagaraja empirical predictions show that the proposed model provides a better performance for site separation distance and elevation angle. The overall performance of the proposed site diversity model is good, and the percentage error is within the allowable error limit approved by International Telecommunication Union – Region (ITU-R)

Characteristics of Measured Rainfall Rate at Ogbomoso, Nigeria for Microwave Applications

Characteristics of rainfall rate useful in the estimation of attenuation due to rain are presented. Rain data collected at Ogbomoso between January-October, 2009 were used in the analysis. Result shows that power law relationship exists between the equiprobable rain rates of two different integration times. The value of conversion factor CE and CR obtained for Ogbomoso are 0.28(60) and 0.64(90) respectively. Our result then shows that different conversion factor is required for different location even within the same climatic region

GENETIC ALGORITHM APPROACH TO SYNTHESIS OF 2, 2 FULL ADDER LOGIC NETWORK

The problem of synthesizing a minimum cost logic circuit is formulated via a genetic algorithm (GA). The synthesis proposes a scheme that “evolves” the minimized logic solution of a defined input function. A method employed combines the available logic gates in several of ways until a minimized and best result is achieved. The result obtained showed a considerable improvement over the existing methods. Key words: genetic algorithm, logic synthesis, full adder network and sum of products form

Spleen Salvaging Treatment Approaches in Non-parasitic Splenic Cysts in Childhood

The aim of this study was to evaluate our experience with primary non-parasitic splenic cysts (NPSC) which are relatively rare in children and consist almost exclusively of single case reports or small case series in the literature. The medical records of all patients who presented to our clinic with NPSC between 2005 and 2015 were evaluated retrospectively. There were 22 children whose ages ranged from 2 months to 14 years (mean 9.2 +/- 4.7 years). The size of the cysts was in the range of 5 to 200 mm (mean 55.4 +/- 48.2 mm). Ten patients underwent surgery for splenic cysts. Partial splenectomy (n = 2), total cyst excision (either open n = 4 or laparoscopically n = 1), and total splenectomy (n = 3) were performed. The non-operated patients were asymptomatic and followed with ultrasound (US). The follow-up period in non-operated patients ranged from 6 months to 5 years (mean 2.27 +/- 1.29 years). Complete regression was observed in four (33 %) non-operated patients. The regressed cyst measurements were 10, 16, 30, and 40 mm, respectively. Approximately half of the NPSC is diagnosed incidentally. Small (< 5 cm) asymptomatic cysts should be under regular follow-up with US/physical examination for regression. If surgery is required, we prefer open cyst excision as it gives excellent results and preserves splenic immune function