149 research outputs found
Aerosols Loading Trends and its Environmental Threats Over Cotonou-Benin.
Environmental security is totally relegated in countries of West Africa. The monitoring of the aerosols loading over Cotonou was the aim of this study. The outcome of our finding has salient links to food security, aviation and communication industry, thermal comfort and climate system of Benin. Cotonou is located on longitude 2.43°E and latitude 6.37°N. Fifteen years data were obtained from the multiangled spectro-reflectometry (MISR). The aerosol loading was monitored using analytical and statistical techniques. The aerosols retention over Cotonou was high in 2000 (69.91%), 2008 (72%) and 2013 (42.45%). This means that there is the possibility of higher rising sea levels and exposure to coastal erosion due to a twisted cloud formation
Rain Induced Cross Polarization on Satellite Communication in Nigeria
Microwave systems performance on satellite communication link operating above 10 GHz
is increasingly degraded by rain when designing telecommunication systems. Cross polarization
is one of the major source of signal degradation that affectthe frequency reuse when employed to
boost capacity of the channel. The effect of cross-polarization in thirty-seven (37) stations in Nigeria
were carried out using 10 years data obtained from Nigeria Meteorological Agency (NIMET) at the
look angle from Nigeria Communication Satellite (NigComSat). International Telecommunication
Union-Recommendation (ITU-R) model was used to for this study. The stations were grouped
into six geopolitical zones in Nigeria which are Southwest (SW), Southeast (SE), South-south (SS),
Northcentral (NC), Northwest (NW) and Northeast (NE). The results reveal that cross-polarization
discrimination (XPD) become very poor as frequency (at Ku-band, Ka-band, V-band) increases
especially at lower percentage of time (such as 0.001%, and 0.01%) unavailability. Hence XPD,
at all frequencies is poorer in the southern part of Nigeria SE, SS and SW due to high rainfall rate.
The results also show that only Northern part of the country will experience no interference at 0.01%
as XPD is over 30 dB ITU-R base line for Ku-band transmission. However, for Ka-band and V-band
at 0.001% and 0.01% unavailability of time interference will occur in all stations in Nigeria, but at
0.1% and 1% XPD is over 30 dB for all stations. This study will help in the adequate planning and
designing of satellite telecommunication expansion in all the six geopolitical zones in Nigeria
Dynamics of Wind Strength and Wind Direction on Air Pollution Dispersion
The aim of the study is to examine the wind dynamics of Ota to understand certain atmospheric influences. An average volume of about four hundred and eighty thousand (480,000) wind speed data from the Davis weather station data logger of the department of physics, covenant university were considered. The data studied were divided into eight hour period, namely, night time (10pm to 6am following day); day time (6am to 2pm) and noon/evening time (2pm to 10pm). Of the three periods studied, wind speed at night time was observed to be the least. December, January and February (DJF) data set was statistically analyzed. The correlation coefficient values recorded with the wind flow for the months of DJF are 0.28 for December, 2012, 0.20 for January, 2013, and 0.39 for February, 2013. While a significant low correlation coefficient values observed for the months of March, April and May (MAM) are 0.02 for March, 0.01 for April and 0.04 for May. A further daily analysis was conducted for February. A significant occurrence of atmospheric stagnation was observed in the night time readings of February 3, 2013 with an exceptional low average wind speed of 0.143 ms-1. While February 17, 2013 recorded all day normal air ventilation with wind speed of 1.443 ms-1, 1.998 ms-1, 4.482 ms-1 for night, day and noon/evening time respectivel
Theoretical Study of Aerosols Loading and Retention Over Bolgatanga, Ghana
The aerosols loading and retention over West Africa have grave effect on life-forms through the impact on health, farming, rainfall
pattern, cloud formation, and regional climate. Bolgatanga can be found on the latitude and longitude of 10.78°N and 0.85°W, respectively.
This research is focused on an investigative consideration of the negative effect of atmospheric aerosols over Bolgatanga in Ghana through
a conceptual model using analytical and descriptive statistical methods with MATLAB curve-fitting tool. The model was verified using aerosol
optical depth data set from satellite imagery—multi-angle imaging specto-reflectometer (MISR)—obtained over a period of 13 years. The
highest percentage increase of aerosol retention was 64.27% over the research site. The model was used to estimate the atmospheric constants
as 0.67, tuning constants as 0.24, and phase difference as ± π
4 . The physical interpretation of the results was analyzed systematicall
Low Cost Real-Time Portable Pulse Oximeter with Wireless Network
To facilitate quicker detection of symptoms of cardiovascular and respiratory disorders,
the use of smaller portable wireless sensors which consume less power is an essential
requirement. Wireless pulse oximeter are convenient devices which aid to remotely
monitor a patient’s heart rate and blood oxygen saturation (SpO ), The result of this
studyshows a developed portable, low cost device which can be used to measure the
heart rate, and SpO of an individual. To this end, a small pulse oximeter was
developed; which used an elastic transmissive mode finger probe to measure the
heart rate and SpO . The device could successfully measure these vital signs and
display on a LCD screen. The readings taken from individual for a period of one
minute shows average heart rate of 75.6 bpm at zero offset and the average SpO
readings derived from the device was 98.7% at zero offset. The model designed is
also rechargeable to make it more sustainable for use in rural areas where there is
insufficient power supply. The prototype pulse oximeter designed is portable,
consumes less power and capable of sending processed measured data to an online
database via a WLAN network thereby satisfying the criteria for sustainable
telemedicine.This device is therefore recommended for use in local hospitals and
remote medical centre to aid easier detection and prevention of critical medical
disease
A Tropical Model for Analyzing Radio Refractivity: Selected Locations in North Central, Nigeria
The effect of climatic global change has altered the
meteorological factor of the ITU model especially in the lower
atmosphere. The refractivity results obtained in an active
tropical region of West Africa need to be reappraised. A model
known as the Tropic model was derived and tested using NOAA
data set. The data set were obtained from Meteorological data
obtained from NOAA (USAF) Climatology center. Radiosonde
data set was at least 39 years between 1973-2012 for six stations
within the North-central of Nigeria. It was observed that the
Tropic model detected tropospheric perturbations caused by the
extensive influence of aerosol influx. This was confirmed by the
hourly refractivity obtained from the ITU model. Hence, the ITU
model and the Tropic model are complementary to each other for
an accurate terrestrial radio links calculation
Sectional Investigation of Seasonal Variations of Surface Refractivity and Water Vapour Density over Nigeria
The accurate knowledge of radio refractive and water vapour density of the troposphere is important in the planning, budgeting and designing of transmission and reception of radiowave signals on earth-space path. Hence, there is the need to adopt more precise techniques to analyze the seasonal variation of refractivity and water vapour density over Nigeria. The seasonal variation of refractivity and water vapour density was studied using thirty-nine years meteorological data for forty-eight (48) stations over Nigeria. The forty-eight stations were grouped into nine vegetation and two major climates in Nigeria. Harmonic analysis approach was used in addition to the monthly mean computation. The results show that Forests zones values of refractivity and water vapour density are higher than Savannahs zones values. The refractivity value increases from about 281 N units at Sudarian Woodland in January to about 383.6 N units at Mangrove station in June. Water vapour density value increases from about 5.18 g/m3 at Brush and Thicket station in November to maximum value of about 22.36 g/m3 at Swamp Forest station in May. Results also show that over 80% variations in refractivity and over 70% variations in water vapour density are revealed in the first three harmonics at all the nine stations. The results indicate that the method of harmonic amplitudes and phases give a more analytical comparison between predictions model and observational data
Re-Integrating Vocational Technical Skill Acquisition into the Educational Curriculum: Capacity Building for Future Professionals
One of the observable problems facing most developing nations today is the non-availability of adequately trained and well-motivated professionals with the capacity to solving problems of national development. Many University graduate professionals complain of unemployment. However, there exist substantial employment opportunities in Africa and other developing nations but the major challenge being that, the skills to match up with imminent challenges are missing. There is, therefore a need to re-integrate vocational technical skill acquisition into the Educational Curriculum for young professionals with proper mental orientation and practical skills for solving societal problems. This paper underlined the necessity of re-integrating vocational technical education (VTE) courses with special targets on sustainability and capacity building aspect of citizenry lives with a view to ascertain the empowerment of students for self employment after graduation. In a bid to achieve this, the current pedagogical approach and curriculum dynamics employed at the Architecture and Civil Engineering Department of Covenant University Ota, Nigeria was evaluated. Specific reference was made in terms of knowledge application from fabrication, construction in timber, reinforced concrete and steel to the main architectural design project. As regards the capacity building development aspect within the architectural and civil engineering education, the application of the respective vocational technical knowledge, obtained through lectures, site works and work shop practices were of major essence in collaborative design projects. It is expected that the indispensability of VTE courses for a successfully-integrated design would bind every element of the design together in different scales. In this way, the sustainability component of the designs in the studio, engineering workshop practice and energy-efficient design would be put to use. The study recommended the investigation and application of all critical elements of VTE-based curriculum development for a sustainable capacity development of emerging future professionals
Seasonal Variation of Surface Radio Refractivity and Water Vapour Density for 48 Stations in Nigeria
The monthly and seasonal variation of surface
refractivity and water vapour density were studied using thirtynine
years meteorological data for forty-eight stations in Nigeria.
The factors which influence the transmission of radio signals
operating within the troposphere are water vapour and
refractivity. The results show that the surface refractivity and
water vapour density generally have higher values during the
rainy season than dry season at all station studied. Furthermore
the results show that the value of surface refractivity and water
vapour density varies from about 263 N-units and 3 g/m3 in arid
region of Nigeria (North East) to about 393 N-units and 23 g/m3
in the coastal area of Nigeria (South West) respectively. For
optimal performance of terrestrial radio link across Nigeria it is
required to account for the variability of these parameters for
optimal systems design
Investigation of Low Clouds Attenuation on Earth Space Path for some West-Africa Stations
The study investigate the contribution of low clouds,
to signal fade rate, at Ka band in the satellite communication
links on earth-space path(s) to NigComSat 2, from three tropical
locations in West Africa. Extracted cloud cover statistical data
such as average cloud amount, average base height, and
frequency of occurrence, were used to obtain the monthly
variations and seasonal variations for Lagos (6.55o, 3.35o),
Bouake (7.73o, -5.07o) and Bamako (12.53o, -7.95o). Cloud
attenuation statistics were computed for each of the three stations
for their respective uplink and downlink. The uplink and
downlink attenuation ranges between about 0.2 to 1.6 dB and 0.1
to 0.8 dB respectively for Lagos; for Bouake between 0.005 to
0.035 dB and 0.003 to 0.016 dB respectively; finally, for Bamako
between about 0.2 to 2 dB and about 0.1 to 1 dB respectively. The
stations downlink attenuation sets of values are generally about
twice their corresponding uplink attenuation values
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