EFFECT OF SHADOWING AND MULTIPATH FADING ON THE AREA SPECTRAL FOR CELL-EDGE USERS IN HETEROGENEOUS NETWORKS

irrespective of their location. The traditional macro-only network have been proved ineffective when communication signal is required for users located in the cell edge and a certain distance away from the macrocell base station. This is because of excess attenuation of the signal due to fading and shadowing. Multipath fading and shadowing are major causes of performance degradation in mobile communication systems. This phenomenon which arises as a result of propagation effects (like scattering, diffraction and reflection), renders the traditional macro-only network communication with users far away from the macrocell base station and located in the cell edge less effective. The deployment of femtocells around the cell edge of this macrocell helps to reduce the effect of fading and shadowing thereby increasing the overall efficiency of the cellular network. Numerical simulation carried out for the macro-femto heterogeneous network using MATLAB shows how the effect of fading and shadowing was reduced. This holds a great promise for adaptive space-based wireless sensor networks, formation-flying satellites and constellations. http://dx.doi.org/10.4314/njt.v35i2.2

Baseline Radionuclide Distribution Patterns in Soil and Radiation Hazard Indices for Abak, Nigeria

A gamma spectroscopy analysis for the naturally occurring radionuclides 226Ra, 232Th and 40K has been carried out for soil samples collected from communities in Abak Local Government Area of Akwa Ibom State to determine the concentration and distribution patterns of these radionuclides in the study area and to assess the possible radiological risks from the soil. The activity concentration of the samples range from 14.80±1.16Bq/kg to 150.20±11.47Bq/kg with a mean value of 98.709±7.693Bq/kg for 40K; from 14.52±3.49Bq/kg to 42.04±8.59Bq/kg for 238U with a mean of 24.826±5.425Bq/kg and from 3.05±0.27Bq/kg to 7.00±0.58Bq/kg with a mean of 5.172±0.31Bq/kg for 232Th. These values are within international regulatory standards. Assessment of the radiation hazard levels for the area gave values of 18.789±3.102nGy/h for absorbed dose, 0.3±0.05Bq/kg for representative level index, 39.82±6.65Bq/kg for radium equivalent, 0.11±0.02 for external hazard index, 0.18±0.032 for internal hazard index and 0.023±0.004mS/yr for effective dose rate. These indices are much lower than the ICRP permissible limits for soil showing that the soil of the study area poses no radiological threats to the public. Keywords: Radionuclide concentration, radiation hazard index, radium equivalent, internal hazard inde

A Gamma Spectrometeric Analysis and Radium Equivalent Activity Index of Water in Abak, Nigeria: A Baseline Survey

This study evaluated the concentration of radionuclides and radiation hazard indices for water with the use of gamma spectrometer in 10 different communities of Abak Local Government Area of Akwa Ibom State, Nigeria to serve as baseline data on the radiological status of the area. The results show that the commonly occurring radionuclides are not uniformly distributed in the water. The mean activity concentration of 40K, 238U and 232Th in the samples were estimated to be 105.46±8.16 Bq/l, 13.02±3.13 Bq/l and 2.44±0.21; Bq/l respectively. These values are well below internationally determined permissible exposure limits. The hazard indices radium equivalent activity, absorbed dose rate, effective dose rate, external and internal hazard indices had mean values of 24.6±4.06 Bq/l, 11.9±1.92 nGy/h, 0.02±0.002mSv/yr, 0.07±0.01 and 0.1±0.02 respectively.The computed hazard indices are all below the recommended standards. Therefore the water at the present time poses no radiological health threat to the populace. Keywords: Radionuclide concentration, radium equivalent, absorbed dose rate, internal hazard inde

Analysis of Empirical Relationship among Agricultural Lending, Agricultural Growth and Non-Performing Loans in Nigerian Banking System

Increasing levels in Non-Performing loans (NPLs) which has remained an area of great concern contributed to issue of declining agribusiness activities in Nigeria in the 1990s and thereafter. The study examined non-performing loans relationship with agricultural lending and agricultural productivity from 1980 to 2015 in Nigeria. Time series data obtained from CBN were analyzed using, Granger causality test, Pearson correlation, and co-integration as well as error correction models. The empirical analyses revealed that, bilateral Granger causality existed between loans and advances granted to agricultural sector and non-performing loans in Nigeria. Also, growth in GDP has a positive and significant correlation with NPL in Nigeria. In the long run, NPL is positively related to agricultural productivity, growth in the GDP and value of loans and advances offered to agricultural sector. Whereas, in the short run, NPL reacted significantly to the negative influence of interest rate and positive impact of GDP growth rate. The adjustment coefficient of 52% was discovered for the NPL long run equation in Nigeria. It is recommended that short and long- term banking reform policies be adopted to reduce fluctuations in NPLs in the banking system and efforts should be geared towards increased participation of specialized financial institutions as to accelerate investments in agriculture sector

Relative signal strength coverage optimization in indoor and outdoor wireless LAN environments

Fading and obstacles constitute major threats to effective quality of service (QoS) delivery in wireless local area network (WLAN) environments. In this contribution, we investigate the signal quality of indoor and outdoor WLANs over a defined coverage area. We present experimental analysis of case studies that will be useful for further research and validate the system’s performance in practice. Using an optimized form of the pathloss models, a simulation of the system is carried out over short and extended coverage. Simulation results show that signal quality could be effectively managed to improve the system’s performance for both indoor and outdoor environments in the presence of fading and other environmental factors.Facultad de Informátic

PERFORMANCE OF WEANED RABBIT FED GRADED LEVELS OF AFRICAN YAMBEAN IN CASSAVA PEEL MEAL BASED DIETS.

The effect of feeding varying levels of African yambean in cassava peal meal based diet was evaluated in a 12 week feeding trial. Thirty two (32) New Zealand white x Chinchilla crossbred weaned rabbits of about 8 weeks old mixed sexes were randomly divided into 4 treatment groups of 8 rabbits each in a completely randomized design. They were allotted to 4 different diets as follows: African yambean based diets, T1 (control 0%), T2 (10%), T3 (20%) and T4 (30%). The rabbits were housed individually in cages and supplied daily with feed and water ad-libitum under a mixed feeding regime where Ipomea batatas leaves was used as forage supplement. Results obtained from this study showed highly significant difference (P<0.05) in body weight gain, feed intake and feed conversion ratio. Results reveal the inclusion of African yambean up to 20% as protein source in cassava peel meal based diets for weaned rabbits without any adverse effect on performance

Modeling the Dynamic Relationship between Food Crop Output Volatility and Its Determinants in Nigeria

The study modeled the short run and long run food crop output volatility equations in Nigeria. Time series data derived from the FAO data base for Nigeria and publications of the CBN covering the period 1961 to 2010 was used in the study. Unit root test conducted on the specified time series shows that all series were integrated of order one at 1% probability level. The GARCH (1, 1) model was used to generate the food crop output volatility for the selected food crops (i.e. rice, maize, sorghum, cassava and yam). The short-run and long-run elastic cities of food crop output volatility with respect to specify explanatory variables were determined using the techniques of co-integration and error correction model estimation based on the OLS estimation. The empirical results revealed that inflation rate, per capita real GDP, loan guaranteed by ACGSF in the food crop sub sector, harvested area of land for food crop and liberalization policy era had mixed influence on food crop output volatility both in the short and long run periods in Nigeria. The result also showed that harvested area of land for the selected food crop was the most important factor that affects food crop volatility in the country. In addition, food crop volatility show an average declines pattern in the liberalization policy period. The study however advocated for appropriate short and long term policy packages that should addressed appropriately the identified significant macroeconomic shifters of food crop output volatility in the country. Also attention should be directed towards improving the quality of land allocated to food crop sub sector. Furthermore, agricultural policies in the liberalization policy package should be design in the short term basis and use as a means for altering food crop output in Nigeria. Keyword: food, crop, volatility, GARCH, inflation, land, policies, loa

Relative signal strength coverage optimization in indoor and outdoor wireless LAN environments

Fading and obstacles constitute major threats to effective quality of service (QoS) delivery in wireless local area network (WLAN) environments. In this contribution, we investigate the signal quality of indoor and outdoor WLANs over a defined coverage area. We present experimental analysis of case studies that will be useful for further research and validate the system’s performance in practice. Using an optimized form of the pathloss models, a simulation of the system is carried out over short and extended coverage. Simulation results show that signal quality could be effectively managed to improve the system’s performance for both indoor and outdoor environments in the presence of fading and other environmental factors.Facultad de Informátic