M. L. Akinyemi

Parametric retrieval model for estimating aerosol size distribution via the AERONET, LAGOS station.

The size characteristics of atmospheric aerosol over the tropical region of Lagos, Southern Nigeria were investigated using two years of continuous spectral aerosol optical depth measurements via the AERONET station for four major bands i.e. blue, green, red and infrared. Lagos lies within the latitude of 6.465°N and longitude of 3.406°E. Few systems of dispersion model was derived upon specified conditions to solve challenges on aerosols size distribution within the Stokes regime. The dispersion model was adopted to derive an aerosol size distribution (ASD) model which is in perfect agreement with existing model. The parametric nature of the formulated ASD model shows the independence of each band to determine the ASD over an area. The turbulence flow of particulates over the area was analyzed using the unified number (Un). A comparative study via the aid of the Davis automatic weather station was carried out on the Reynolds number, Knudsen number and the Unified number. The Reynolds and Unified number were more accurate to describe the atmospheric fields of the location. The aerosols loading trend in January to March (JFM) and August to October (ASO) shows a yearly 15% retention of aerosols in the atmosphere. The effect of the yearly aerosol retention can be seen to partly influence the aerosol loadings between October and February.

A Simple Technique for Sustaining Solar Energy Production in Active Convective Coastal Regions

The climatic factors in the coastal areas are cogent in planning a stable and functional solar farm. 3D simulations relating the surface temperature, sunshine hour, and solar irradiance were adopted to see the effect of minute changes of other meteorological parameters on solar irradiance. This enabled the day-to-day solar radiation monitoring with the primary objective to examine the best technique for maximum power generation via solar option in coastal locations. The month of January had the highest turbulent features, showing the influence of weather and the poorest solar radiance due to low sunshine hour. Twenty-year weather parameters in the research area were simulated to express the systematic influence of weather of PV performance. A theoretical solar farm was illustrated to generate stable power supply with emphasis on the longevity of the PV module proposed by introducing an electronic concentrator pillar (CP). The pictorial and operational model of the solar farm was adequately explained.

Prospects of solar energy in the coastal areas of Nigeria

The climatic factors in the coastal areas are cogent in planning a stable and functional solar farm. The experiment performed in this study entails a day-to-day solar radiation pattern in coastal areas. The results show that the solar radiation pattern in coastal region portends danger to the performance of solar photovoltaic (PV) module and its lifecycle. The efficiency of the PV module was tested in the harmattan where dust is a major hindrance. The results were related to meteorological parameters which influences the solar radiation over an area. The solar radiation pattern in coastal areas was traced to the solar sectional shading theory which was summarized and explained.

Short-duration exposure to 2.45 GHz microwave radiation induces DNA damage in Sprague Dawley rat’s reproductive systems

-1 . Potential damage at the organ level was assessed by histopathological study. The results show significant differences in the Olive moment and % DNA in the blood of the exposed animals when compared with the control (p < 0.05). Hyperchromasia was observed in the ovary of the animals exposed to MW radiation. Also, there was reduction in the number of germ cells and cell disorganization in the testis of exposed group with increasing SARs. These results suggest that MW radiation has the potential to affect both male and female fertility adversely.

Performance and Evaluation of Eight Cloud Models on Earth—Space Path for a Tropical Station

This is a review of eight cloud models and a statistical analysis of radiosonde data and cloud cover data in order to obtain attenuation distributions and cloud cover statistics for a tropical location, Ota (6.7oN, 3.23oE) at a computed elevation angle of 56.18o to an Astra 2B satellite located at 31.5oE. Cloud models are mathematical algorithms scientifically designed to predict cloud attenuation impact on propagating electromagnetic signals in the troposphere, using data on each model’s required parameters such as temperature, pressure, cloud height, cloud occurrence and liquid water content of clouds. The station’s cloud cover statistics, namely average amount of cloud, cloud base height, and frequency of occurrence were computed from extracted cloud data to obtain their monthly and seasonal variations. The results show that minimum attenuation values were predicted by both the Gun and East and the ITU-R models, while the Liebe and Slobin models predicted consistently maximum values of attenuation for all the cloud models tested. Cloud attenuation statistics computed for each of the models show that at 0.01% exceedance probability, the averages of the predicted cloud attenuation for uplink and downlink at Ota, ranges between 0.45 dB and 0.44 dB for Ku, 1.85 dB and 0.75 dB for Ka, and 3.50 dB and 2.50 dB for V bands. At 0.1% the averages are between 0.30 dB and 0.27 dB, 0.95 dB and 0.47 dB, 2.45 dB and 1.51 dB at Ku, ka and V bands for both uplink and downlink respectively.

Radiation from Visual Display Unit

The radiation from different types of Visual Display Units (VDU) (that is, Liquid Crystal Display (LCD) and Cathode Ray Tube (CRT)), projector and interactive screen were examined using a Cell Sensor Extremely Low Frequency (ELF) detection meter. The study revealed that ELF radiation in CRT VDUs is eight (8) times greater than in LCD VDUs. The mean ELF obtained from interactive screen at 30 cm was 1.6 mG and 1.9 mG at start-up and after 3 hours of use respectively with a mean value of 1.03 mG for a distance of 100 cm at start up. The mean ELF radiation from the projector screen at a distance of 10 cm is 0 mG, while that of interactive screen is 2.4 mG at the same distance. Thus, the study suggested that, projector and screen is better than interactive screen when making presentation considering the closeness of user to the interactive screen throughout the course of presentation.

Review on Li-Fi: an advancement in wireless network communication with the application of solar power

Light Fidelity, commonly referred to as Li-Fi is a technology that was introduced by a German physicist called Herald Hass. This technology in its own uniqueness considers the use of light (Light Emitting Diode, LED to be specific) as its medium of delivering high speed communication that complies with standard IEEE 802.15.7 bidirectional communication standard. This optical means of communications is also known as visible light communication. It is safer when compared with Wi-Fi network. This paper will focus on Li-Fi applications, comparison with existing technologies like Wi-Fi and the inclusion of an alternative source of power i.e., solar power, as a means of effectively optimizing on the availability and accessibility of the benefits in places where erratic or total power outage is a common trend.

Cloud attenuation modelling for satellite network links performance improvement

All local climate zones need to develop relevant climatic models such as cloud attenuation model which can serve as correlative resources to global satellites applications and a means of determining local link margins for satellite networks services in localities. Effects of suspended water droplets (SWD) and suspended ice crystals (SIC) which constitute clouds are major concern in the design and successful operation of satellite communication system at frequencies above 3GHz because the hydrometeors reduces the services availability critically as frequency increases. This work is a review of cloud attenuation modelling, using as a case study typical research work been carried out, to develop cloud attenuation model for tropical Ota (6.7oN, 3.23oE), southwest Nigeria. Cloud attenuation modelling for a station involve obtaining clouds parametric system equation from their numerical representations, taking into consideration the climatic initial and boundary conditions. The numerical representations are collected climatological and radiometric data, derived from well-designed experiments in which cloud parameters measurements are carried out using radiances change measured by satellites and visual observations from the surface station(s) on land and ships in the ocean. The on-going research work begin with the study of performance of eight foundation cloud models at the station, through their detailed evaluation from cloud cover data and radiosonde data analysis, followed by analysis of collected over three years spectrum analyser signal attenuation data. Then modelling analysis of the station spectrum analyser data collected at computed elevation angle 56.18o to Astra 2(E-G) Satellite located at 28.2oE, which involve comparisons of the derived attenuation distribution curves, both of the spectrum analyser data and those of the existing cloud models for the station, with the derived attenuation distribution curves of output data generated by each run session of the station simulation equation program. The general representation of the station cloud attenuation model is stated and the specific model equation is been worked on.

Dataset on the current state of air pollution in Bussau-Guinea Bussau: A diagnostic approach

Recent UN report shows that over 100,000 people die from air pollution. The general anthropoenic pollution from Sahara desert, fossil-fuel engines and bush-burning needs to be reduced to avoid natural accidents, regional climate change etc. A fifteen years dataset was obtained from the Multi-angle Imaging Spectro-Radiometer (MISR). The dataset generated from the primary dataset would assist to understand the state of air pollution over Bussau. It also serves as a reference to guide the choice of ground measuring equipments in the area. The aerosol constant and tunning constant over Bussau is 0.6694 and 0.1354 respectively. The maximum percentage aerosol loading is given as 14.8%.

A short review on the effects of aerosols on visibility impairment

Ozone in the lower planetary boundary layer of the earth atmosphere is dangerous to people and vegetation, since it oxidizes natural tissue. The diminished in visibility is because of dispersing of sun based radiation by high convergences of anthropogenic aerosols. Visibility impairment is most prominent at high relative mugginess when the aerosols swell by the takeup of water to expand the cross sectional area for dispersing; this is the wonder known as haze. Haze has become a major air pollution challenge the aviation industry has to cope with in recent time. In this review, two major problems were spotted to be responsible for air disaster in any region of the world. While some developed countries had almost resolved the challenge of visibility impairment by seeking relevant solutions, most developing countries do not have a recovery plan. Therefore, the resolution of this major challenge may be the leverage for most developing nations to draw out a recovery plan.