Characterization of magnetic field horizontal component in selected stations along the 210o MM

Characterizing the magnetic field horizontal component (H) variability helps to better accommodate the irregular fluctuations inthe electron/ion density of the ionosphere for mitigating short-wave radio communication and Global Navigation Satellite Systems (GNSS) disruptions. This study employed three year data (2007-2009) from Magnetic Data Acquisition System (MAGDAS) facilities at six (6) observatories along the 210o magnetic meridian (MM) for investigating hourly, seasonal and annual variations in the horizontal component of the Earth’s magnetic field. The baseline value of H was computed from its average value near local midnight hours between 2400 and 0100 local time (LT) and subtracted from other hours value for the hourly variation; while the monthly and annual averages were computed for seasonal and yearly analysis respectively. Results indicates that maximum values of Sq are recorded in equinoctial season with an annual peak value of 70.96 nT for year 2009 recorded at Langkawi (LKW) as against the lowest peak value of 27.45 nT recorded in Cooktown (CKT) at 1300LT. Keywords: Magnetic field, horizontal component, solar quiet, seasonal variation, solar equinox

Use of spectral decomposition technique for mapping geologic features of ‘Reigh’ field, Onshore Niger Delta

Spectral Decomposition Technique based on Short-Window Discrete Fourier Transform (SWDFT) was applied to threedimensional (3D) seismic data obtained from ‘Reigh’ field, onshore Niger Delta with a view to enhancing stratigraphic interpretation for geological features which are beyond seismic resolution. Two sands units from the study area were studied to produce spectrally decomposedsurfaces. The result of the study revealed thin bed layer at the centre of the field on sand unit ‘A’. Sand-filled meandering channel wasdetected and highlighted in the northern part of sand unit ‘B’ based on Red-Green-Blue frequency modulation of spectral decomposition. The study has enhanced geologic understanding of the field by improving thin bed resolution, highlighting geologic features and displaying bed thickness variation of studied sand units in the study area. Keywords: geologic features, Niger Delta, seismic data, spectral decomposition

Thermal Response at Room Temperature and Device Applications of Two Wood Species in Akure, South Western Nigeria

Thermal properties (Density, Thermal conductivity and Specific heat capacity) play important impact in the formation of devicesmade of wooden materials. This study examines the room temperature thermal response of ten bulk samples from the species of Pterygota macrocarpa and Antiaris africana wood species found in South Western Nigeria. The samples were processed into appropriate shapes to fit into the parallel plane arrangement to determine the thermal properties. Temperature dependent models were used to obtain the specific heat capacities of the samples within a temperature variation of 308.25𝐾 - 310.00𝐾. The results revealed that the thermal properties (thermal conductivities and specific heat capacities) increase as temperature increases for all the bulk samples considered. The results of the research showed that the selected wood samples could find useful applications in industrial insulating devices. Keywords: Wood material, Lee’s disc apparatus, Temperature and Thermal properties.

The effect of electrodes on the voltage generation of microbial fuel cell

Microbial fuel cell (MFC) is a device that coverts the chemical energy contents of organic matter to electrical energy by the catalytic action of microorganisms. Cow dungs as organic substrates were used in three sets of dual chambered MFCs to study the effects ofelectrodes on the open circuit voltage (OCV) generation of MFC. The anode and cathode compartments were connected using a protonexchange membrane, 1 kg of the cow dung diluted with 500 ml of water was introduced in the anode compartment of each of the setups. The electrode configurations for set-up 1, 2 and 3 respectively were Carbon-Carbon(C-C), carbon-copper(C-Cu) and carbon- zinc(C-Zn). Samples for microbial load count were collected every two days from the anode compartment of the MFC and analyzed using standard microbiological methods. The OCV of the three setups were measured daily for two weeks using a digital multimeter. The microbial load ranged from 4.2 × 104 to 8.5 × 104 CFU/ml for bacteria and 2.1 × 102 to 2.3 × 103 CFU/ml for fungi. The range (average) of the OCV obtained from the set-ups were 0.06 to 0.72 V (0.42 V) for the C–C; 0.02 to 0.67 V (0.26 V) for C-Cu and 0.11 to 0.78 V (0.39 V) for the C-Zn. The OCV for the C-C electrode combination showed an increasing trend while the OCV of C-Cu and C-Zn showed decreasing trends with increasing number of days. The C-C electrode combination gave the best OCV. Keywords: microbial fuel cell, open circuit voltage, electrodes, organic substrate

Determination of thermal properties of some ceiling material commonly used in Ijebu- Ode, Nigeria

The study investigates the thermal properties of different insulating material used in building construction in Ijebu Ode, a tropical rainforest region, south western, Nigeria. Five insulating material; asbestos, Plaster of Paris (P.O.P), PolyVinyl Chloride (PVC), hardboard and paperboard, were subjected to thermal investigation using Lee’s disc electrical method. The result obtained showed that the thermal conductivities obtained are within the range of values specified for good insulating materials. Asbestos was found to be associated with the least thermal conductivity of the value 𝟎. 𝟏𝟕𝟏𝟕 𝑾𝒎-𝟏𝑲-𝟏while PVC had the highest thermal conductivity values of 𝟏. 𝟔𝟒𝟗𝟗 𝑾𝒎-𝟏𝑲-𝟏. This may be associated with the temperature and the heat flux on the surface of the material. The results obtained for thermal conductivity, thermal resistivity and thermal diffusivity correlated favourably when compared with those of previous work from other locations. Asbestos being the material with the lowest thermal conductivity is therefore recommended for use as the suitable insulating ceiling material in the study area. Keywords: thermal conductivity, diffusivity, resistivity, Lee’s disc

Development of Alternating Current (AC) Line Monitoring Device for Power System Management

This work presents a study of the effect of imbalance between the supply of and demand of power from the National grid on electrical appliances. In the study, an alternating current (ac) line monitoring device was developed using arduino microcontroller to carry out the investigation. The device is a single system capable of measuring both the main frequency and nominal voltage of electricity supply. The device consists of seven major components: 12 V step-down transformer, half-wave rectifier, attenuator, wave-shaping circuit, arduino microcontroller, Liquid crystal display and micro SD card. The heart of the device is the arduino microcontroller that reads the period of the pulses from the shaping circuit and the output voltage from the scale resistor connected to the attenuator circuit in order to measure the levels frequency and voltage of the ac main source. By graphically compared the reading of the voltage obtained by the ac monitoring device with that of the standard Mastech voltmeter, it was shown that the device has a good correlation with the standard voltmeter with a deviation of ±0.21%, and this has proven that the device is capable of measuring ac voltage accurately. From the frequency test level results, it was found that the frequency measured by the device closely related to the frequency measured by the standard frequency meter. This shows that the device satisfied the requirement of the overall design. Hence, it can be used in the laboratory for demonstration and research purposes as well as in power plant industries. Keywords: Mains frequency, nominal voltage, half-wave rectifier, attenuator, wave-shaping circuit, Arduino microcontroller

Meteorological parameter anomalies and anomalous radio propagation over Nigeria

Distribution and variation of anomalous radio propagation, temperature and relative humidity anomalies were obtained and analyzed using six years (2010-2015) Era interim data. Seasonal spatial distribution of refractivity gradient and its components were analyzed. The result showed that about 90% of wet component contributed to the variation of refractivity gradient. Highest range of refractivity gradients and its wet components were obtained during the wet season. The result of correlation between ducting occurrence and temperature showed strong negative correlation except in Lagos where positive correlation of 3% was observed. However, positive correlation which ranges between 39% and 70% exist between duct occurrence and relative humidity except in Lagos in Nigeria. Refractivity gradients, relative humidity anomaly and temperature experience a monthly variation. These variations can be attributed to the seasonal movement of inter-tropical discontinuity (ITD) across Nigeria. Keywords: anomalous, anomaly, correlation, ITD

Analysis of visibility effects on free space earth-to-satellite optical link based on measurement data in Nigeria

The effect of atmospheric variables on signals propagating from earth to space are of concern in the design and performance of wireless communications systems. Since atmospheric effects which led to atmospheric losses (attenuations, fading and scintillation) are location-dependent, climatological phenomena such as fog, snow, rain, and haze has much effect on Free Space Optical (FSO) and can cause reduction in the link availability. This paper analysed the effect of fog on FSO communication links from earth to satellite links over five selected locations (Ikeja, Akure, Enugu, Jos and Port-Harcourt) in Nigeria. One year (2012) visibility data obtained at Nigeria Meteorological Agency (NIMET) have been used to estimate the specific attenuation caused by fog on FSO communication links in the selected locations. Link margin was deduced in all the five locations. The estimated specific attenuation caused by fog was based on operating frequencies associated with a typical commercial FSO. The result shows that at 352 THz frequency, Ikeja recorded the highest value of about 38.60 dB/km for the specific attenuation due to fog on FSO link followed by Akure with value of about 30.33 dB/km. Enugu recorded the least estimated attenuation of about 14.19 dB/km . The implication of the result is that Ikeja and Akure will suffer more signal loss, while Enugu will suffer less signal loss. Result on link margin performed on FSO link also showed that Ikeja has the highest link margin of -109.79 dB, Port-Harcourt with link margin value of -91.99 dB while Jos experienced lowest link margin of about -37.48 dB. Keywords: Free space optical systems; Fog induced specific attenuation; Earth-space links; Link margin

Chaotic assessment of the key performance indicators for a GSM Network congestion in an election period in Nigeria

This paper investigates the chaos-based assessment of the Key performance Indicators (KPIs) for the Cellular network congestion during and after 2011 People Democratic Party (PDP) presidential primary election in Eagle Square within Abuja and its environs. Chaotic quantifiers such as average mutual information, Lyapunov exponents and specific attenuation were employed to study the congestion rate or dynamical state of the network. The chaotic assessment of the Wideband Code Division Multiplexing Access (WCDMA) data services provided by MTN network using KPIs are reported. The data retrieved from the three Base Transceiver Stations (BTSs) were used to analyse the performance of the network. The results revealed the state of dynamical behaviour of the congestion during the study period. Keywords: Key performance Indicators (KPIs); Wideband Code Division Multiplexing Access (WCDMA); Global System of Mobile communication (GSM); Base Transceiver Station (BTS); Chaotic Quantifiers

Soil-to-maize Transfer Factor of Natural Radionuclides in a Tropical Ecosystem of Nigeria

Soil-to-plant transfer factor (TF) is a parameter utilized in predicting the accumulation of radionuclides in the plant system. Virgin soil from an uncultivated area and tailings from an abandoned tin mining site were used to formulate three soil groups. Group A (virgin soil only), group B (tailings only) and group C (equal mixture by mass of the virgin soil and tailings). Pot experiments were performed using the soil groups to determine the transfer factors of 40K, 238U and 232Th in maize (Zea mays L.) plants for the tropical ecosystem of Nigeria. The activity concentrations of 40K, 238U and 232Th in the soil groups and the maize plant compartments (seed, stem, leaf and root) were determined using NaI(Tl) gamma-detector. The geometric mean (GM) of the TF values for 40K, 238U and 232Th respectively ranged from 0.02 to 0.27, below detectable limit (BDL) to 0.008 and 0.01 to 0.09 in the in the seeds; 0.04 to 1.74, BDL to BDL and 0.01 to 0.29 in the stems; 0.03 to 0.93, BDL to 0.33 and 0.02 to 0.08 in the leaves and 0.03 to 1.29, 0.05 to 0.38 and 0.08 to 0.41 in the roots.. Potassium-40 had the highest TF values and exhibited the plant accumulation strategy for all the plant compartments. The stem samples had the highest TF for 40K and BDL values for 238U for all the soil groups. Significance differences were observed only in the accumulation of 40K and 232Th across the soil group. Keywords: Radioactivity, potassium, mining, Gamma-ray detectors, calibration