Abstract: The levels of maximum power density of GSM
signals in the cities of Lagos, Ibadan and Abuja were studied.
Measurements were made with a calibrated hand held spectrum
analyzer 200m away from 271 base stations, at 1.2m to the ground
level. The maximum GSM 900 signal power density was
139.63μW/m2 in Lagos, 162.49μW/m2 in Ibadan and 5411.26μW/m2
in Abuja. Also, the maximum GSM 1800 signal power density was
296.82μW/m2 in Lagos, 116.82μW/m2 in Ibadan and 1263.00μW/m2
in Abuja. The level of power density of GSM 900 and GSM 1800
signals in the cities of Lagos, Ibadan and Abuja are far less than the
recommended value of 4.5W/m2 for GSM 900 and 9.0 W/m2 for
GSM 1800 by the ICNRP guideline. It can be concluded that
exposure to GSM signals in these cities cannot contribute to the
health detriments caused by thermal effects of radiofrequency
radiation.
Abstract: Particles are the most common and cheapest
reinforcement producing discontinuous reinforced composites with
isotropic properties. Conventional fabrication methods can be used to
produce a wide range of product forms, making them relatively
inexpensive. Optimising composite development must include
consideration of all the fundamental aspect of particles including
their size, shape, volume fraction, distribution and mechanical
properties. Research has shown that the challenges of low fracture
toughness, poor crack growth resistance and low thermal stability can
be overcome by reinforcement with particles. The unique properties
exhibited by micro particles reinforced ceramic composites have
made them to be highly attractive in a vast array of applications.
Abstract: This paper reveals the interaction between hydrogen
and surface stress in austenitic stainless steel by X-ray diffraction
stress measurement and thermal desorption analysis before and after
being charged with hydrogen. The surface residual stress was varied
by surface finishing using several disc polishing agents. The obtained
results show that the residual stress near surface had a significant
effect on hydrogen absorption behavior, that is, tensile residual stress
promoted the hydrogen absorption and compressive one did opposite.
Also, hydrogen induced equi-biaxial stress and this stress has a linear
correlation with hydrogen content.
Abstract: Aluminum hybrid reinforcement technology is a
response to the dynamic ever increasing service requirements of such
industries as transportation, aerospace, automobile, marine, etc. It is
unique in that it offers a platform of almost unending combinations of
materials to produce various hybrid composites. This article reviews
the studies carried out on various combinations of aluminum hybrid
composite and the effects on mechanical, physical and chemical
properties. It is observed that the extent of enhancement of these
properties of hybrid composites is strongly dependent on the nature
of the reinforcement, its hardness, particle size, volume fraction,
uniformity of dispersion within the matrix and the method of hybrid
production.
Abstract: Marine Protected Areas can benefit from nature based
tourism, monitoring environmental impacts and also become target
for human presence. From more than 3 million tourists visiting
Cozumel Island every year, an average of 2,8 million arrive by cruise
ship, and 41% are estimated to have motivation for water activities.
The destination is relying so much on the tourism activity, that scuba
diving and snorkeling in the National Park Reef of Cozumel sustain
the major economic activity. In order to achieve the sustainable
development indicator designed for regional environmental
development, the PNAC offers a training course to tourism providers
to access the protected area. This way, the update of the last 5 years
of such training is directed to diving staff, boat crew and
professionals, making them able to assist in managing the natural
resource. Moreover, the case study is an example to be used for
raising awareness among tourists visiting protected areas.
Abstract: Taro Scarab beetles (Papuana uninodis, Coleoptera:
Scarabaeidae) inflict severe damage on important root crops and
plants such as Taro or Cocoyam, yam, sweet potatoes, oil palm and
coffee tea plants across Africa and Asia resulting in economic
hardship and starvation in some nations. Scoliid wasps and
Metarhizium anisopliae fungus - bio-control agents; are shown to be
able to control the population of Scarab beetle adults and larvae using
a newly created simulation model based on non-linear ordinary
differential equations that track the populations of the beetle life
cycle stages: egg, larva, pupa, adult and the population of the scoliid
parasitoid wasps, which attack beetle larvae. In spite of the challenge
driven by the longevity of the scarab beetles, the combined effect of
the larval wasps and the fungal bio-control agent is able to control
and drive down the population of both the adult and the beetle eggs
below the environmental carrying capacity within an interval of 120
days, offering the long term prospect of a stable and eco-friendly
environment; where the population of scarab beetles is: regulated by
parasitoid wasps and beneficial soil saprophytes.
Abstract: Drying behavior of blanched sweet potato in a cabinet
dryer using different five air temperatures (40-80°C) and ten sweet
potato varieties sliced to 5mm thickness were investigated. The
drying data were fitted to eight models. The Modified Henderson and
Pabis model gave the best fit to the experimental moisture ratio data
obtained during the drying of all the varieties while Newton (Lewis)
and Wang and Singh models gave the least fit. The values of Deff
obtained for Bophelo variety (1.27 x 10-9 to 1.77 x 10-9 m2/s) was
the least while that of S191 (1.93 x 10-9 to 2.47 x 10-9 m2/s) was the
highest which indicates that moisture diffusivity in sweet potato is
affected by the genetic factor. Activation energy values ranged from
0.27-6.54 kJ/mol. The lower activation energy indicates that drying
of sweet potato slices requires less energy and is hence a cost and
energy saving method. The drying behavior of blanched sweet potato
was investigated in a cabinet dryer. Drying time decreased
considerably with increase in hot air temperature. Out of the eight
models fitted, the Modified Henderson and Pabis model gave the best
fit to the experimental moisture ratio data on all the varieties while
Newton, Wang and Singh models gave the least. The lower activation
energy (0.27 - 6.54 kJ/mol) obtained indicates that drying of sweet
potato slices requires less energy and is hence a cost and energy
saving method.
Abstract: A relationship between face and signature biometrics
is established in this paper. A new approach is developed to predict
faces from signatures by using artificial intelligence. A multilayer
perceptron (MLP) neural network is used to generate face details
from features extracted from signatures, here face is the physical
biometric and signatures is the behavioural biometric. The new
method establishes a relationship between the two biometrics and
regenerates a visible face image from the signature features.
Furthermore, the performance efficiencies of our new technique are
demonstrated in terms of minimum error rates compared to published
work.
Abstract: This research focuses on the optimization of glazed
surfaces and the assessment of possible solar gains in industrial
buildings. Existing window rating methods for single windows were
evaluated and a new method for a simple analysis of energy gains and
losses by single windows was introduced. Furthermore extensive
transient building simulations were carried out to appraise the
performance of low cost polycarbonate multi-cell sheets in
interaction with typical buildings for industrial applications. Mainly
energy saving potential was determined by optimizing the orientation
and area of such glazing systems in dependency on their thermal
qualities. Moreover the impact on critical aspects such as summer
overheating and daylight illumination was considered to ensure the
user comfort and avoid additional energy demand for lighting or
cooling. Hereby the simulated heating demand could be reduced by
up to 1/3 compared to traditional architecture of industrial halls using
mainly skylights.
Abstract: The effect of Zn2+, Mg2+, and Ba2+ on Saccharomyces
pastorianus performance was evaluated in this study at independent
and three variable combinations. After 96 h of fermentation, high
wort fermentability (%F) = 29.53 was obtained in medium containing
900:4 ppm Mg2+ + Ba2+. Increased ethanol yield 7.35 %(v/v) and
7.13 %(v/v) were obtained in media containing 900:4 ppm Mg2+ +
Ba2+ and 12:900 ppm Zn2+ + Mg2+. Decrease %F = 22.54 and ethanol
yield 6.18 % (v/v) was obtained in medium containing 12:4 ppm Zn2+
+ Ba2+. In media containing the individual ions, increased %F =
27.94 and 26.03 were recorded for media containing 700 ppm Mg2+
and 2 ppm Ba2+ , with ethanol yield of 7.88% (v/v) and 7.62% (v/v)
respectively. Reduced %F and ethanol yield was observed for 10 ppm
Zn2+ and 4 ppm Ba2+ media. The impact of Ba2+ at 1 and 2 ppm was
significant.
Abstract: The paper deals with current issues in research of
advanced methods to increase reliability of traditional timber
structural elements. It analyses the issue of strengthening of bent
timber beams, such as ceiling beams in old (historical) buildings with
additional concrete slab in combination with externally bonded fibre -
reinforced polymer. The paper describes experimental testing of
composite timber-concrete beam with FRP reinforcement and
compares results with FEM analysis.
Abstract: The study area is Zaria, located in the basement
complex of northern Nigeria. The rock type forming the major part of
the Zaria batholith is granite. This research work was carried out to
compare the responses of seismic refraction tomography and
resistivity tomography in the same geologic environment and under
the same conditions. Hence, the choice of the site that has a visible
granitic outcrop that extends across a narrow stream channel and is
flanked by unconsolidated overburden, a neutral profile that was
covered by plain overburden and a site with thick lateritic cover
became necessary. The results of the seismic and resistivity
tomography models reveals that seismic velocity and resistivity does
not always simultaneously increase with depth, but their responses in
any geologic environment are determined by changes in the
mechanical and chemical content of the rock types rather than depth.
Abstract: A total of 150 meat type chickens comprising 50 each
of Arbor Acre, Marshall and Ross were used for this study which
lasted for 10 weeks at the Federal University of Agriculture,
Abeokuta, Nigeria. Growth performance data were collected from the
third week through week 10 and data obtained were analysed using
the Generalized Linear Model Procedure. Heritability estimates (h2)
for body dimensions carried out on the chicken strains ranged from
low to high. Marshall broiler chicken strain had the highest h2 for
body weight 0.46±0.04, followed by Arbor Acre and Ross with h2
being 0.38±0.12 and 0.26±0.06, respectively. The repeatability
estimates for body weight in the three broiler strains were high, and it
ranged from 0.70 at week 4 to 0.88 at week 10. Relationships
between the body weight and linear body measurements in the broiler
chicken strains were positive and highly significant (p > 0.05).
Abstract: In this study, a comparative analysis of the approaches
associated with the use of neural network algorithms for effective
solution of a complex inverse problem – the problem of identifying
and determining the individual concentrations of inorganic salts in
multicomponent aqueous solutions by the spectra of Raman
scattering of light – is performed. It is shown that application of
artificial neural networks provides the average accuracy of
determination of concentration of each salt no worse than 0.025 M.
The results of comparative analysis of input data compression
methods are presented. It is demonstrated that use of uniform
aggregation of input features allows decreasing the error of
determination of individual concentrations of components by 16-18%
on the average.
Abstract: The work proposes a decision support methodology
for the credit risk minimization in selection of investment projects.
The methodology provides two stages of projects’ evaluation.
Preliminary selection of projects with minor credit risks is made
using the Expertons Method. The second stage makes ranking of
chosen projects using the Possibilistic Discrimination Analysis
Method. The latter is a new modification of a well-known Method of
Fuzzy Discrimination Analysis.
Abstract: Analysis of real life problems often results in linear
systems of equations for which solutions are sought. The method to
employ depends, to some extent, on the properties of the coefficient
matrix. It is not always feasible to solve linear systems of equations
by direct methods, as such the need to use an iterative method
becomes imperative. Before an iterative method can be employed
to solve a linear system of equations there must be a guaranty that
the process of solution will converge. This guaranty, which must
be determined apriori, involve the use of some criterion expressible
in terms of the entries of the coefficient matrix. It is, therefore,
logical that the convergence criterion should depend implicitly on the
algebraic structure of such a method. However, in deference to this
view is the practice of conducting convergence analysis for Gauss-
Seidel iteration on a criterion formulated based on the algebraic
structure of Jacobi iteration. To remedy this anomaly, the Gauss-
Seidel iteration was studied for its algebraic structure and contrary
to the usual assumption, it was discovered that some property of the
iteration matrix of Gauss-Seidel method is only diagonally dominant
in its first row while the other rows do not satisfy diagonal dominance.
With the aid of this structure we herein fashion out an improved
version of Gauss-Seidel iteration with the prospect of enhancing
convergence and robustness of the method. A numerical section is
included to demonstrate the validity of the theoretical results obtained
for the improved Gauss-Seidel method.
Abstract: Strontium hexaferrite (SrFe12O19; Sr-ferrite) is one of
the well-known materials for permanent magnets. In this study, Mtype
strontium ferrite was prepared by following the conventional
ceramic method from steelmaking by-product. Initial materials;
SrCO3 and by-product, were mixed together in the composition of
SrFe12O19 in different Sr/Fe ratios. The mixtures of these raw
materials were dry-milled for 6h. The blended powder was presintered
(i.e. calcination) at 1000°C for different times periods, then
cooled down to room temperature. These pre-sintered samples were
re-milled in a dry atmosphere for 1h and then fired at different
temperatures in atmospheric conditions, and cooled down to room
temperature. The produced magnetic powder has a dense hexagonal
grain shape structure. The calculated energy product values for the
produced samples ranged from 0.3 to 2.4 MGOe.
Abstract: The use of low quality concrete has been identified as one of the main causes of the incessant collapse of buildings in Nigeria. Emphasis has been on the use of poor quality aggregates, poor workmanship and the use of lean concrete mix with low cement quantity as the reasons for the low quality of concrete used for building construction in Nigeria. Surveys conducted revealed that in the construction of most privately owned buildings where concrete trial mixes and concrete compressive strength quality assurance tests are not conducted, concretes used for building constructions are produced using the 1:2:4 mix ratio irrespective of the cement grade/strength class. In this paper, the possible role of the use of inappropriate cement grade/strength class as a cause of the incessant collapse of building in Nigeria is investigated. Investigation revealed that the compressive strengths of concrete cubes produced with Portland-limestone cement grade 32.5 using 1:2:4 and 1:1.5:3 mix ratios are less than the 25MPa and 30MPa cube strengths generally recommended for building superstructures and foundations respectively. Conversely, the compressive strengths of concrete cubes produced with Portland-limestone cement grade 42.5 using 1:2:4 and 1:1.5:3 mix ratios exceed the 25MPa and 30MPa generally recommended for building superstructures and foundations respectively. Thus, it can be concluded that the use of inappropriate cement grade (Portland-limestone cement grade 32.5), particularly for the construction of building foundations is a potential cause of the incessant collapse of buildings in Nigeria. It is recommended that the Standards Organisation of Nigeria should embark on creating awareness for Nigerians, particularly, the home owners and the roadside craftsmen that Portland-limestone cement grade 32.5 should not be used for the construction of building load-carrying members, particularly, building foundations in order to reduce the incessant incidence of collapsed building.
Abstract: Climate change and poverty are global issues which cannot be waved aside in welfare of the ever increasing population. The causes / consequences are far more elaborate in developing countries, including Nigeria, which poses threats to the existence of man and his environment. The dominant role of agriculture makes it obvious that even minor climate deteriorations can cause devastating socio-economic consequences. Policies to curb the climate change by reducing the consumption of fossil fuels like oil, gas or carbon compounds have significant economical impacts on the producers/suppliers of these fuels. Thus a unified political narrative that advances both agendas is needed, because their components of an environmental coin that needs to be addressed. The developed world should maintain a low-carbon growth & real commitment of 0.7% of gross national income, as aid to developing countries & renewable energy approach should be emphasized, hence global poverty combated.
Abstract: Flood routing is used in estimating the travel time and attenuation of flood waves as they move downstream a river or channel. The routing procedure is usually classified as hydrologic or hydraulic. Hydraulic methods utilize the equations of continuity and motion. Kinematic routing, a hydraulic technique was used in routing Asa River at Ilorin. The river is of agricultural and industrial importance to Ilorin, the capital of Kwara State, Nigeria. This paper determines the kinematic parameters of kinematic wave velocity, time step, time required to traverse, weighting factor and change in length. Values obtained were 4.67 m/s, 19 secs, 21 secs, 0.75 and 100 m, respectively. These parameters adequately reflect the watershed and flow characteristics essential for the routing. The synthetic unit hydrograph was developed using the Natural Resources Conservation Service (NRCS) method. 24-hr 10yr, 25yr, 50yr and 100yr storm hydrographs were developed from the unit hydrograph using convolution procedures and the outflow hydrographs were obtained for each of 24-hr 10yr, 25yr, 50yr and 100yr indicating 0.11 m3/s, 0.10 m3/s, 0.10 m3/s and 0.10 m3/s attenuations respectively.