Socio-Technical Perspective for Electronic Tax Information System in Tanzania

Socio-technical systems theory has rarely been used by system architects in setting up computing systems. However, the role of socio-technical concepts in computing, which is becoming social in nature, has made the concepts more relevant and commercial. Tax information systems are examples of such systems because they are influenced by external variables such as the political environment, technological trends, and social environment, introducing complexity in their deployment and determining the type of e-services and their delivery to a diverse group of people. It was observed that in Tanzania there is resistance, reluctance and minimal use of electronic tax system because of insufficient end-user support and their involvement in constructing the system. Therefore, there is need to develop an electronic tax information system using socio-technical systems perspectives to ensure design of an efficient user-friendly tax administration system. The research used the qualitative approach, featuring case studies in Korea, Chile, Tanzania, and Denmark. The study used best practices from the Organization for Economic Cooperation and Development (OECD) to benchmark Tanzania Revenue Authority current practices. It was found that tax models implemented are techno-centric push models, which don’t attract its use by tax payers and requiring human intervention in its operation, hence not cost-effective. As the first and relevant phase in socio-technical system development, this paper presents the problem definition and analysis of e-Tax collection system in Tanzania.

Prediction of four-days Soaked California Bearing Ratio (CBR) Values from Soil Index Properties

California Bearing Ratio (CBR) laboratory testing is the conventional method for determining soaked strengths of pavement subgrades. The test requires careful preparation of soil samples followed by four days of water soaking before penetrating the samples using a standard plunger at prescribed rates to set depths. When the number of samples becomes large the determination of soaked CBR values becomes cumbersome as the test is laborious and time consuming. This study aimed at establishing an alternative way of determining soaked CBR by developing a model that would be used for estimating soaked CBR of fine- and coarse- grained soils without performing the CBR test. This has been achieved by correlating CBR values compacted at 95% Maximum Dry Density (MDD) with the soil index properties. The results show that soaked CBR values of fine-grained soils significantly correlate with specific gravity of soil (GS), Plasticity index (PI) and the grading modulus (GM) of the soil that yields a degree of determination of R2 = 0.91 and for coarse grained (A-2 type) soil, the soaked CBR values significantly correlate with specific gravity of soil and percentage of fines passing 0.075mm sieve size that yields a degree of determination of R2= 0.94.

Determination of CRLB and Minimum Variance Unbiased Estimator of a DC Signal in AWGN Using Laplace Transform

This paper presents an alternative approach for the determination of Cramer-Rao Lower Bound (CRLB) and Minimum Variance Unbiased Estimator (MVUE) using Laplace transformation. In this work, a DC signal in Additive White Gaussian Noise (AWGN) was considered. During the investigation, a number of experiments were conducted to analyze different possible outputs under different conditions, and then the patterns of the outcomes were studied. Finally closed-form expressions for the CRLB and MVUE were deduced employing the Laplace transformation. The resulting expressions show that the proposed method has almost the same number of steps as the existing method. However, the later requires only the knowledge of algebra to arrive at the CRLB expressions contrary to the existing approach where a strong mathematical background is required and hence making it superior over the existing method, in that sense.

Prediction of Uniaxial Compressive Strength of Granite Rock Samples of Lugoba Quarry Using Rebound Hammer Test

Rebound hammer test is widely used as an indirect measure of uniaxial compressive strength for engineering materials such as concrete, soil, and rock in both civil and mining engineering works. In quarries, uniaxial compressive strength is a crucial parameter in the analysis of geotechnical problems involving rock stability and rock blasting design. This study aims at establishing the empirical models of uniaxial compressive strength fits on rebound hammer number that can be used to predict uniaxial compressive strength of granitic rock at Lugoba Quarry. Data for direct uniaxial compressive strength were obtained from uniaxial compressive strength test carried out on 20 core samples at the Dar es Salaam Institute of Technology Geotechnical Laboratory using ISMR Standard Procedures. The rebound hammer test was carried out using testing hammer type N. The tests were done horizontally on two scanline's geotechnical domains of the rock mass on the footwall side of the quarry. The obtained results of UCS ranging from 105 to 132.5 MPa and RHN from 44.90 to 49.5 were found to be comparable with values of other granitic rocks in other parts of the world. Regression Analysis using SPSS software was carried out to develop 5 regression models of UCS vs.RHN. The values of obtained in this study were found to be between 0.93 and 0.95, which are comparable with other studies. This implies that RHN accounted between 93 and 95% of the total variation of the UCS and the relationships were very strong. Two models; Logarithmic and exponential were found to be appropriate and recommended for application at Lugoba Quarry.

Rheological Properties of Aged Crude Hard Wood Pyrolysis Oil

Upon storage of the pyrolysis oil, aging reactions may initiate phase separation and change of the rheological properties. These changes lead to unfavourable fuel characteristics in handling, transportation and applications. Efforts have been made for alleviation including methods on how to avoid these aging effects and development of equipment capable of handling aged pyrolysis liquids with unfavourable fuel characteristics. Therefore, the aim of this study was to explore the rheological properties of phase separated pyrolysis liquid fuel. Two batches of a well – stored poplar wood pyrolysis oils were used for the investigation; one batch was diluted with water to represent the oils undergoing severe phase separation (forced phase separation), and another batch was not diluted. Steady and dynamic rheological tests were conducted at various temperatures. Homogeneous (whole oil) and the bottom phases of pyrolysis oils were used. Results revealed that the whole oils of both diluted and undiluted oils exhibited low viscosity Newtonian behaviours at higher temperatures and high viscosity non-Newtonian behaviours at low temperatures. The bottom phases of both diluted and undiluted oils exhibited nonNewtonian behaviours with significant higher viscosity than the whole oils. The strain and frequency sweep dynamic tests showed existence of weak structures in the whole oils and strong network structures in the bottom phases. This study suggests that the handling, transportation and application of the pyrolysis oils undergoing phase separation are possible when the oils are treated with higher temperatures predominantly in turbulent state.

Performance of Calcium Chloride- Ammonia Adsorption Refrigeration System

An experimental study on the performance of calcium chloride-ammonia adsorption system is described. A single bed water cooled condenser adsorption refrigerator prototype, which utilises calcium chloride-ammonia pair has been developed and tested in the laboratory. Experiments have been conducted for desorption temperatures of 100 °C with desorption time varying from 1 to 4 hours. An electric tape heater and a timer were used to perform the experiments. The adsorption temperature profile, adsorption rate and prototype performance have been analysed and discussed. The tested heating and desorption temperature of 100 °C and heating and desorption time of 1 to 4 hours was able to create a cooling effect of the cold chamber of the prototype of between -0.8 to 8.3 °C, which is adequate for vaccine storage requirement of 2 to 8 °C. The estimated Coefficient of Performance of the system ranges between 0.025 and 0. 076.

Direct Predictive Speed Control of Salient PMSM Drives in Constant Torque and Constant Power Regimes for Electric Vehicles Applications

A direct speed control of salient permanent magnet synchronous motor (PMSM) drives in constant torque and constant power regimes for electric vehicles applications is presented. The proposed speed control scheme is derived from model predictive control approach where both rotor speed and stator current are formulated in a single objective function that is periodically computed to attain the PMSM drive optimum switching states. The dynamic model of the PMSM intrinsically encompasses the unknown disturbance, which should be rejected for high-performance speed control especially in transient conditions. Consequently, the extended modified augmented state Kalman filter (ASKF) is incorporated in the proposed scheme to enhance the transient performance of the salient PMSM drive. Finally, the proposed speed control strategy reveals a fast-transient speed response when compared to the conventional dual current loop PI-based speed controller over extended speed range and load torque variations. The computer simulation conducted using MATLAB/Simulink and experimental results obtained using PMSM laboratory prototype are presented considering constant torque and constant power regions to confirm the efficacy of the proposed speed control strategy.

Deconvolution of Mono-Energetic and Multi-Lines Gamma-Ray Spectra Obtained with NaI(Tl) Scintillation Detectors Using Direct Matrix Inversion Method

Performance of a NaI(Tl) scintillation detector based on the gamma-ray spectroscopy system is not satisfactory in retaining its original peak (which is delta like function) of various gamma ray spectrum. The method of achieving precise peak for the various gamma ray was conducted by converting the observed pulse-height distribution of the NaI(Tl) detector to a true photon spectrum. This method is obtained experimentally with the help of an inverse matrix deconvolution method. The method is based on response matrix generated by the Monte Carlo simulation based on Geant4 package of mono-energy gamma-ray photon ranging from 0.050 to 2.04 MeV in the interval of 10 keV. The comparison of the measured and simulated response function was also performed in order to authenticate the simulation response function. Good agreement was observed around the photo-peak region of the spectrum, but slight deviation was observed at low energy region especially below 0.2 MeV. The Compton backscattering and Compton continuum counts was significantly transferred into the corresponding photo-peak and consequently the peak to total(P/T) ratio was improved. The P/T ratio results obtained after application of the deconvolution method taken with three calibration sources with gamma-ray’s energies of 81 keV, 303 keV and 356 keV (for 133Ba), 662 keV (for 137Cs), 1173 keV and 1333keV (for 60Co), were improved from(to) 0.50(0.90), 0.40(0.83), 0.57(0.93), 0.31(0.92), 0.18(0.84) and 0.15(0.83), respectively.