Open Access Original Research Article

Thermal Diffusivity Variations at Ministry of Agriculture Akure South, Ondo State, South–West Nigeria

K. D. Adedayo, J. S. Ojo, I. E. Okoroafor

Physical Science International Journal, Page 1-10
DOI: 10.9734/PSIJ/2017/24135

Thermal diffusivity variations of different soil types in a tropical location, Akure, Nigeria at three different depths over dry and wet seasons are presented. The time lag method was used to estimate the thermal diffusivity (D) of the experimental site using the hourly and mean weekly temperature distribution alongside soil properties such as moisture content, bulk density, porosity and soil heat capacity, at the depths of 30, 40, and 50 cm. Soil type include sandy clay for the 30 cm depth and sandy loamy clay for the 40 and 50 cm depths. Results obtained show a larger variation of thermal diffusivity, having an average value of 59.68 x 10 -7 m2/s in the wet season as compared to 1.41 x 10-7 m2/s for the dry season. Strong correlation exists between the diurnal variation of soil temperature modeled based on different depths and the measured values.

 

Open Access Original Research Article

Natural Radioactivity Levels and Radiological Risk Assessment of Surface Water from Coastal Communities of Ndokwa East, Delta State, Nigeria

C. P. Ononugbo, C. D. Anyalebechi

Physical Science International Journal, Page 1-14
DOI: 10.9734/PSIJ/2017/31782

Aims: The aim of this study is to measure the natural radioactivity levels in surface water from coastal communities in order to assess the radiological health hazards associated with the use of such water.

Study Design: This study was purely an experimental work.

Place and Duration of Study: Abalagada, Agwe-Etiti, Asemuku, Aboh and Okpai coastal communities of Ndokwa –East, Nigeria: between April – December, 2016.

Methodology: 20 samples of surface water were collected from five coastal communities with pre-washed 2.0 l Polypropylene bottles. The bottles were rinsed with the water before collection and acidified immediately after collection with few drops of HCL. The bottles were sealed tightly with vinyl tapes and kept in the laboratory for 4 weeks for secular equilibrium of the radionuclides. The activity concentration of the radionuclides were measured using Sodium Iodide detector.

Results: Activity concentrations of 238U, 232Th and 40K  in surface waters in five communities ranges from BDL to 4.49±1.01 Bql-1 with an average value of 2.37±0.10 Bql-1, BDL to 10.03± 1.04 Bql-1 with average value of 4.19±0.23 Bql-1 and 3.07±0.95 to 34.94±10.77 Bql-1 with an average value of 15.82±2.03 Bql-1 respectively. The activity concentration of 232Th and 40K were higher than their reference values of 1.0 and 10.0 Bql-1. The total effective doses due to ingestion of radionuclides in water are 58.48, 3.195 and 6.243 mSvy-1 for infants, children and adults respectively which are higher than the recommended reference level of 0.26, 0.2 and 0.1 mSv of committed effective dose from one year ingestion of water for infants, children and adults. The estimated lifetime fatality cancer risk to adult shows that approximately 442 out of 10,000,000 may suffer some form of cancer fatality and for the lifetime hereditary effect approximately 274 out of 1000,000,000 may suffer some hereditary effects. Statistical analysis shows that positive correlation exists between the three radionuclides indicating same origin.

Conclusion: Oil and gas production activities within the coastal communities has radiologically impacted the surface water of the area and could lead to radiation health risk of public that uses that water.

 

Open Access Original Research Article

Green’s Function (GF) for the Two Dimensional (2D) Time Dependent Inhomogeneous Wave Equation

Akpata Erhieyovwe, Umukoro Judith, Enaibe A. Edison

Physical Science International Journal, Page 1-17
DOI: 10.9734/PSIJ/2017/31687

Interference effect that occurs when two or more waves overlap or intersect is a common phenomenon in physical wave mechanics. A carrier wave as applied in this study describes the resultant of the interference of a parasitic wave with a host wave. A carrier wave in this wise, is a corrupt wave function which certainly describes the activity and performance of most physical systems. In this work, presented in this paper, we used the Green’s function technique to evaluate the behaviour of a 2D carrier wave as it propagates away from the origin in a pipe of a given radius. In this work, we showed quantitatively the method of determining the intrinsic characteristics of the constituents of a carrier wave which were initially not known. Evidently from this study the frequency and the band spectrum of the Green’s function are greater than those of the general solution of the wave equation.  It is revealed in this study that the retarded behaviour of the carrier wave described by the Green’s function at some point away from the origin is much greater than the general wave solution of the carrier wave at the origin.  The Green’ function is spherically symmetric about the source, and falls off smoothly with increasing distance from the source. The anomalous behaviour exhibited by the carrier wave at some point during the damping, is due to the resistance pose by the carrier wave in an attempt to annul the destructive tendency of the interfering wave. Evidently it is shown in this work that when a carrier wave is undergoing attenuation, it does not consistently come to rest; rather it shows some resistance at some point in time during the damping process, before it finally comes to rest.

 

Open Access Review Article

Spatial Variation Modeling of Geothermal Gradient and Heat Flow in Eastern Parts of Niger Delta Sedimentary Basin, Nigeria

Emujakporue Godwin Omokenu, L. I. Nwosu

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2017/31581

The aims of this research are to carry out statistical and geostatistical analysis of geothermal data and to determine the spatial variation of geothermal gradient and heat flow of parts of Niger delta sedimentary basin. Corrected Bottom hole temperatures from 18 deep oil wells were used for the computation of geothermal gradient and heat flows. The data were compiled from previous work. Both statistical and geostatistical analysis involving histogram, variogram, and ordinary kriging were applied to the data. The computed geothermal gradient values range from 16 – 33 oC/Km while the heat flow ranges from 23 to 70 mW/m2. The statistical analysis of the geothermal gradient shows that the minimum, maximum, median, mean and standard deviation are; 15.57, 33.66, 21.27, 22.51 and 5.07 respectively. The most occurrence geothermal gradient interval in the histogram is 20-24°C/Km with a frequency of 9. For the heat flow values, the minimum, maximum, median, mean and standard deviation are: 21.99, 70.31, 44.19, 45.44, and 13.92. The most occurring heat flow interval is 51-61 mW/m2 with a frequency of 5. The experimental variograms for the geothermal gradient and heat flow were modelled with spherical and Gaussian functions respectively. The heat flow variogram has nugget effect. The values of variances are assumed to be the values of the sill of the geothermal gradient and heat flow in the study area. The omnidirectional variogram provides a good interpretations for the spatial relationships for the two data sets. The ordinary kriging maps obtained from the variogram models for the geothermal gradients and heat flows provided a very good estimate for the un-sampled points. The geothermal gradient in the study area from the ordinary kriging ranges from 18 to 34.0°C/km, with an average value of 25.5°C/km. The geothermal gradient shows that the southeast region is associated with high values while northwest and central parts have low geothermal gradient respectively. The estimated heat flow from the ordinary kriging analysis ranges from 24 to 70 mW/m2, with an average of 47.0 mW/m2. The maximum heat flow occurs in the eastern and parts of the southwest regions. The lowest heat flow which trend in the northwest to southeast directions is found in the central region of the study area.

 

Open Access Review Article

The Role of Nanotechnology on Photovoltaic Cells

Pigweh Isa Amos

Physical Science International Journal, Page 1-6
DOI: 10.9734/PSIJ/2017/32757

Advances in the field of Nanotechnology has shown great promise to enhance the photoconversion of photovoltaic cells and hence improved electrical output. This breakthrough in terms of efficiency seems meager when compared to the crystalline silicon solar cells. However, Quantum dots Nanocrystals has the potential to achieve higher efficiency because their bandgap can be tuned to absorb a wider range of the electromagnetic spectrum, and also, they can generate multiple excitons through impact ionization process. This Review paper discusses the basic principles of Photovoltaic effects, efficiency and Shockley-Queisser limit, the major drawbacks of silicon-based PV cells, the function of Quantum dots Nanocrystals to improve efficiency and finally the advantages of Quantum dots.