Wind Power Integration and Its Impact on Power Quality - A Didactic Approach

This paper presents a model of a wind power system integrated with realistic power system, with intention of using it in addressing power quality issues in relations to grid codes during steady-state operation transient-state operation i.e., presence of grid fault events. For that case, a didactic approach of the normal performance of power systems due to the connection of fixed-speed wind turbine with induction generators is used. A study of integrating wind farms will be presented, including the incidence of high inrush current due to switching capacitor banks, out-rush current and voltage sags due to nearby three phase faults. As mandatory for the grid codes regulation, the incidence on the power quality at the point of common coupling is analyzed too. As a result of the contingency study, it will be shown that capacitors bank and fault current limiter can help the wind farm to ride-through a fault

Water and wildlife in the Serengeti-Mara ecosystem

Surface water is a key resource for wildlife conservation and its spatial and temporal distribution is important in understanding the distribution and composition of large herbivore assemblages in savannah ecosystems. Unprecedented continual decline in surface water availability in these ecosystems pose a threat to ungulates abundance and landscape use. But how changes in surface water will affect large herbivores has inadequately been investigated. Here we quantified drivers of changes in surface water in the Serengeti-Mara ecosystem and furthermore quantified changes in surface water availability affect the distribution and composition of large herbivore communities. We studied how fire and livestock grazing affect surface water availability and subsequently wildlife landscape use. Furthermore, we quantified water requirements of savannah ungulates using six different functional traits related to water loss pathways. We found that between 1972 and 2018, human activities upstream and outside protected area have changed the recession time scale for Mara River while the lack of human activities in the Serengeti National Park has maintained the hydrological properties of the Mbalageti River. Furthermore, we observed a wide range of water requirements among ungulates with two major groups of water dependent and independent species. In addition, this study provides evidence that each functional trait can be independently used to predict water requirements and in particular proposes that minimum dung moisture content is an easy to measure index of water requirement. Importantly, we showed that water requirements add a new dimension of niche partitioning for grazing ungulates that is independent of body size

Impact of Saving and Credit Cooperative Societies in Poverty Reduction. Empirical Evidence from Tanzania

The objective of the study was to examine the impact of Saving and Credit Cooperative Societies (SACCOS) in Poverty Reduction. The study was justified based on the fact that poverty level and microfinance services change continuously and therefore a lot remains to be desired. Descriptive as well as multiple linear regression methods were used in this study which involved a sample of 40 beneficiaries of microfinance services. Microfinance services and entrepreneurial skills were independent variables and poverty reduction was the dependent variable. Data analysis was done using Statistical Package for Social Sciences (SPSS). The findings revealed that microfinance services contribute 50 percent of poverty reduction indicating the strong impact of SACCOs in poverty reduction given that the loans are invested in income generating activities. SACCOs beneficiaries have experienced increased income, improved social services and self employment.  The study further revealed that SACCOs provide entrepreneurial skills although at a very small rate and the training provided meant to create member’s awareness of terms and conditions of loans and savings and not creating business skills. This study recommends that SACCOs need to ensure that microfinance services provision is expanded to include large number of clients. Furthermore, I recommend SACCOs to introduce entrepreneurial training to all members and ensure simultaneous provision of microfinance services and entrepreneurial skills for effective poverty reduction. Keywords: microfinance services, entrepreneurial skills, investment and poverty reduction

Adaptive Sliding Mode Contouring Control Design Based on Reference Adjustment and Uncertainty Compensation for Feed Drive Systems

Industrial feed drive systems, particularly, ball-screw and lead-screw feed drives are among the dominating motion components in production and manufacturing industries. They operate around the clock at high speeds for coping with the rising production demands. Adversely, high-speed motions cause mechanical vibrations, high-energy consumption, and insufficient accuracy. Although there are many control strategies in the literature, such as sliding mode and model predictive controls, further research is necessary for precision enhancement and energy saving. This study focused on design of an adaptive sliding mode contouring control based on reference adjustment and uncertainty compensation for feed drive systems. A combined reference adjustment and uncertainty compensator for precision motion of industrial feed drive systems were designed. For feasibility of the approach, simulation using matlab was conducted, and results are compared with those of an adaptive nonlinear sliding model contouring controller. The addition of uncertainty compensator showed a substantial improvement in performance by reducing the average contour error by 85.71% and the maximum contouring error by 78.64% under low speed compared to the adaptive sliding mode contouring controller with reference adjustment. Under high speed, the addition of uncertainty compensator reduced the average and absolute maximum contour errors by 4.48% and 10.13%, respectively. The experimental verification will be done in future. Keywords:    Machine tools, Feed drive systems, contouring control, Uncertainty dynamics, Sliding mode control

The Perceptions of Teachers, Parents and Students on the Effects of Mobile Phone Use on Student Learning in Tanzania

The use of mobile phones enables learners to interact with vast resource materials to facilitate learning. Yet in Tanzania, mobile phones are strictly prohibited in many schools. This study examined parents’, teachers’ and students’ perceptions of the effects of students’ access to mobile phones on students learning performance. It was conducted in four selected secondary schools in Dodoma municipality. Both qualitative and quantitative research methods were employed as data were collected from 280 respondents through questionnaire, interview schedule and documentary review. Cross-tabulation and Chi-square tests were among data analysis techniques employed in the understanding of different perceptions of respondents. The findings show that, parents and teachers agree that students with mobile phones perform poorly and misbehave more often than students without mobile phones. Also, in order to have value-based control system for appropriate use of mobile phones, providing proper education on mobile phone use and re-introducing censorship board to control the quality of contents on websites are recommended. Keywords: mobile phone use in school, effects of mobile phone use on academic performance, school mobile phone use policy in Tanzania

Understanding Pre-service Teachers’ Emotion Experience During Teaching Practice in Tanzania: Causes, Management Strategies and the Impacts in Teaching

Teacher‘s emotions serves as a central aspect of teachers’ life as it govern classroom interactions and have a significant impact on students’ learning. There are various factors that are associated with causing emotions and influencing teacher emotions like individual expectations, working environments or interaction patterns between sides. Given this, the study was structured to understand pre-service teachers’ emotional experience during teaching practices. Specifically, the study sought to examine the causes, management strategies and its impact in the process of teaching and learning. Data were collected from 87 participants who were pre-service teachers who had been in teaching practice for eight weeks. The quantitative data collected were analysed by using MS excel 2007 and presented in descriptive statistics while qualitative data were analysed by using thematic analysis and supported with direct quotes. The findings show that pre-service teachers experienced emotions when their expectations about students’ performances and active engagement were not met as well as when they achieved their goals of creating active learning environments. In situations that generated negative emotions, pre-service teachers sought advice from experienced teachers, they engaged in refreshing activities like listening to music, playing games or in classroom situations they were flexible to change to more interesting and engaging methods. The findings further revealed that impact of emotional experience is in two folds. On one side teachers become motivated to try new innovation and creativity when they experience positive emotion while on the other side they become discouraged when they experience negative emotions. Based on these findings, it is recommended that more studies on emotional dissonance should be conducted to help broader understanding of teacher emotions and how they can help improve their teaching. Keywords: emotion experience, pre-service teachers, teacher education, teaching practice DOI: 10.7176/JEP/11-9-12 Publication date:March 31st 202

Rural Electrification using Iliceto Shield Wire Scheme in Developing Countries: Tanzania Case Study

Rural electrification rate in Tanzania is still very low despite the efforts made by the Rural Energy Agency (REA) in Tanzania. Rural electrification using medium voltage (MV) method has two major obstacles. First obstacle is high cost associated with the cost of extending the grid electricity to rural areas. Second obstacle is remoteness of the villages, which leads to high power loss during transmission. In lieu of economic extension of rural electrification areas, this paper proposes a low cost solution of Iliceto Shield Wire Scheme (ISWS). This technique involves insulating shield wires (SW) from high voltage (132-400 kV) transmission line and energizing (11-33 kV) them from nearby substation at one line and use ground as MV phase conductor. The paper undertakes literature review of ISWS technology as installed in other developing countries. After that, a case study is selected in Mpaji village in Tanga region Tanzania. Analysis was made on voltage drop, power flow and cost for rural electrification using ISWS technology. Using ISWS for Mpaji village resulted in 10.89% voltage drop with total investment cost of about 49.4% compared to MV conventional method. Keywords: Iliceto Shield Wire Scheme (ISWS), Medium Voltage, Rural Electrificatio

The Effects of Macroeconomic variables on Economic growth in Tanzania:1980 - 2020

The main purpose of this dissertation work is to scrutinize the effects of macroeconomic variables on economic growth in Tanzania. The study is carried out using annual time series data covering a period of 1980 to 2020. Ordinary Least Square (OLS), Error Correction Models (ECM) and Granger Causality Test have been used to determine the impact of macroeconomic variables on economic growth. Also, the dynamic correlations and innovations of macroeconomic variables and economic growth have been intuitively analysed by undertaking the impulse response function (IRF). OLS results show that economic growth of Tanzania is positively and significant influenced by inflation rate, real exchange rate and government expenditure. Also, the significance of Augmented Dickey-Fuller (ADF) for regression residuals demonstrate an existence of long run relationship among variable. ECM results also ignites the influence of money supply and RER on economic growth in the short run, and significant equilibrium restoration in general. The IRF innovation results suggest that, the policy variables inflation rate, money supply, real exchange rate, trade openness and government expenditure have significant impact on economic growth in Tanzania specifically in the long run, thus some time with lag. Although, as a priori monetary and fiscal policy variables do have a dominant effect on economic activity of any country, this study clearly shows that economic growth in Tanzania is dominated by its own dynamics in most of the periods. Thus, the study recommends right policy mix given the dynamics would have significant impact to the economic growth in Tanzania. Keywords: Economic growth, Macroeconomic variables, ECM, Granger Causality, Impulse Response Function

Stroke in Patients with Schistosomiasis: Review of Cases in Literature

Introduction. Cerebral vascular comorbidities may occur in patients with schistosomiasis, as described in case reports. Aim and Methods. We have summarized general clinical and neurological features in patients with stroke associated with schistosomiasis, through a review of case reports in the literature. Investigation Outcomes. A total of eight case reports were retrieved. The mean age of patients was 36.42 +/- 16.7 (19 to 56 years), four females, three males, and one anonymous sex. Eosinophilia was the most frequent feature at presentation, followed by cardiac abnormalities, confusion, fever, ataxia, hemiplegia, headache, urticaria, dysphasia, and memory impairment. Patients usually present with watershed infarction or intracranial vasculitis. In one case, extracranial carotid arteries presented with inflammation and stenosis. The patient's serology was positive on admission in five cases. Full neurological recovery was reported in three cases, and partial improvement in another three. In two cases, information on neurological outcomes was incomplete. Stroke in schistosomiasis can be caused by haemodynamic impairment, direct lesion to the arterial wall, vasa vasorum obliterative endarteritis, contiguity with a focus of inflamed tissue, or inflammatory intimal damage. Schistosomiasis needs to be included in the differential diagnosis of stroke in people living or coming back from endemic areas. Conclusions. Further studies addressing the noncommunicable comorbidity issues related to this condition are needed

Gendered health impacts of industrial gold mining in northwestern Tanzania: perceptions of local communities

Mining projects affect the health of surrounding communities by inducing environmental, economic, social and cultural changes in different population groups. Health impact assessment (HIA) offers an opportunity to manage these impacts. This paper aims to explore gender differences of impacts on the wider determinants of health as described by communities impacted by industrial gold mining and consider the implications for impact assessment. We conducted 24 gender-separated, participatory focus group discussions at three study sites in northwestern Tanzania. Participants reported on a broad range of impacts on the wider determinants of health. Based on a thematic analysis, we identified gendered health impacts on men and women; in addition, children and adolescent boys and girls emerged as differently affected subpopulation groups. Located in the theory of the 'triple role of women', we suggest that different gender needs should be addressed more explicitly by HIA. Increased use of mitigation measures that recognise and address impacts on women's engendered roles, and their health, through addressing women's strategic gender needs, would strengthen HIA as a tool towards sustainable development