Abstract:The efficiency of the thermoelectric materials and devices is shown by the dimensionless Figure of merit, ZT. ZT is calculated by multiplying the Seebeck coefficient with square of the electrical conductivity and absolute temperature and dividing it all by the thermal conductivity. Thermoelectric devices were prepared using different multilayered thin film structures in the order of SiO 2 /SiO 2 + Ge/Ge/Sb + Ge/Si/Si + Ge/Ge/Ge + Si by DC/RF Magnetron Sputtering. The prepared thermoelectric devices have been tailored with 5 MeV Si ions bombardment at the different fluences (doses) to form quantum structures in the multilayer thin films to improve the efficiency of the thermoelectric devices. Seebeck coefficients, van der Pauw-four probe resistivity, Hall Effect coefficient, density and mobility have been measured. After the samples were prepared, SEM/EDS data were collected. FIB/SEM images were provided to figure out the cross-section of the fabricated devices. Seebeck coefficients and electrical resistivity results were affected positively if the appropriate ion beam dose was selected.

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The evaluation of gross alpha and beta activities in crude oil contaminated soil, sediment and water samples was conducted in ten oil polluted environment of Delta State using Gas-flow proportional counter. Samples were collected from the oil polluted environment in each oil field and samples were prepared and analyzed following standard procedures. The mean gross alpha and beta activities obtained are 331.4 ± 24.5 Bq kg −1 and 11,335 ± 112 Bq kg −1 respectively for soil, 259.2 ± 17.6 Bq kg −1 and 4508 ± 96 Bq kg −1 respectively for sediment, and 1.00 ± 0.09 Bq kg −1 and 20.3 ± 1.7 Bq kg −1 respectively for water. The estimated average values of the total annual effective dose equivalent (AEDE T(α,β) ), the total annual gonadal dose equivalent (AGDE T(α,β) ), and the total excess lifetime cancer risk (ELCR T(α,β) ) are 10.64 mSv y −1 , 0.037 μSv y −1 and 0.037 μSv y −1 respectively. The gross alpha and beta activities values obtained in soil and sediment were relatively high compared to values reported in some parts of the country and other regions and countries of the world. The radiological risk parameters examined show that AEDE T(α,β) and AGDE T(α,β) are above recommended permissible limits while ELCR T(α,β) is within the recommended permissible limit. The overall results obtained in this study indicate that the environmental samples have been radiologically impaired due to the crude oil spillage. An appropriate remediation technique was therefore recommended to remediate the polluted soil, sediment, and water to their near original state.

Different signal processing technique performances are compared to each other with regard to separating the mean and fluctuating velocity components of a simulated one-dimensional unsteady velocity signal comparable to signals observed in internal combustion engines. A simulation signal with known mean and fluctuating components was generated using experimental data and generic turbulence spectral information. The simulation signal was generated based on observations on the measured velocity data obtained using LDV in a motored Briggs-and-Stratton engine at about 600 RPM. Experimental data was used as a guide to shape the simulated signal mean velocity variation; fluctuating velocity variations with specified spectrum and standard deviation was used to mimic the turbulence. Cyclic variations were added both to the mean and the fluctuating velocity signals to simulate prescribed cyclic variations. The simulated signal was introduced as input to the following algorithms: ensemble averaging; high-pass filtering; Proper-Orthogonal Decomposition (POD); Wavelet Decomposition (WD) and Wavelet Decomposition/Principal Component Analysis (WD/PCA). The results were analyzed to determine the best method in correctly separating the mean and the fluctuating velocity information, indicating that the WD/PCA performs better compared to other techniques.

An infiltration characteristic model was developed by using the modified Kostiakov method for the Agricultural Engineering demonstration field of Bangladesh Agricultural Research Institute (BARI). The constant values a, α, and b of the equation for accumulated infiltration y = at α + b were 9.12, 0.683, and 0.145, respectively. The average value of percentage of error between the actual and calculated values by the model was only 0.134 and showed very good agreement between the model and the field values of accumulated infiltration. This model will be very helpful for making a good irrigation scheduling and best water management.