Journal Articles

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Landau theoretical interpretation of domain and domain walls in ferroelectric ferroics
(Asian Research Publishing Network, 2006) Rwenyagila, E. R.; Mwanga, S. F.
In this paper some behaviors of domain and domain walls in perovskite ferroics were theoretically investigated. Landau type theory was used to examine the phenomenological properties of domains and domain walls in ferroelectric perovskite materials. Landau predictions on the prototype ferroelectric BaTiO3 showed that it has a stable tetragonal structure at room temperature. The number of domains in the three ferroelectric phases of BaTiO3 was also calculated. The results confirmed six, eight and twelve domain states in the tetragonal, rhombohedral and orthorhombic structures of BaTiO3, respectively. The respective spontaneous polarization and domain wall thickness in the stable tetragonal BaTiO3 have values of 0.26 Cm-2 and 1.63nm at room temperature. Analytical and numerical solutions for the relationship between temperature and domain wall thickness and for the spatial distribution of polarizations inside the domain wall are also determined and discussed.
A logistic regression model of customer satisfaction of airline
(Macrothink Institute, 2012) Peter, Josephat; Abbas, Ismail
Evaluation of customer satisfaction differs from one study to another. Studies have been differing with their focus and coverage. Most of studies focused on evaluating factors influencing customer satisfaction or associate customer satisfaction and quality of services. This paper used logistic regression to develop customer satisfaction model for Precision Air. Five dimensions or variables have been considered: on time performance; aircraft safety; schedule integrity; on board services; and customer service. Data used in this paper were collected from four major regions with many flights. These include Dar es Salaam, Mwanza, Arusha and Kilimanjaro. A sample size of 272 passengers was selected. Convenience sampling was used to select the respondents. Primary data were collected in the field through questionnaire. Findings showed that out of the five independent variables only one variable is negatively related with satisfaction of airline passengers (customer services). In contrast, on time performance was satisfactory variable by most of passengers compared to the rest of explanatory variables. Airline safety, schedule integrity and on board services are positively related with passengers satisfaction. Relationship between customer services and satisfaction are negatively related which implies that, there is a need of finding strategies to improve customer services to customers. The paper recommends that the airline should maintain and improve on time performance as this is crucial variable for passenger’s satisfaction but other variables need more improvement.
Utilization of client service charter: an experience from Dodoma municipal council–Tanzania
(Diva Enterprises Pvt. Ltd.(DE), 2012) Likangaga, R.; Josephat, P.
Inconsistency of Clients Service Charter (CSC) effects and lack of literature on CSC influenced this study to be conducted by examining the utilization of CSC in Local Authorities (LAs) with particular reference to Dodoma Municipal Council. This study employed a case study design. A sample size of 118 clients was purposively selected. The sample comprised 60 internal customers’ and 58 external customers. The study concludes that there is poor utilization of CSC in DMC because since the establishment of the charter, it has not been made public. In addition there is no any effort taken by the DMC management to make it operational. The study found that despite CSC being not implemented, majority of the external customers were satisfied by the services provided by DMC. On the other hand, majority of the internal customers were not satisfactory by the services offered by DMC.
Job and work attitude determinants: An application of multivariate analysis.
(Macrothink Institute, 2012) Josephat, P.; Ismail, A.
This paper analyzed variables that used to measure job and work attitude of an employee in an organization. Analysis was done using multivariate analysis. Data used was collected from Dodoma and Musoma municipalities as the municipalities were randomly selected. A sample size of the study was 118. Cross sectional research design was adopted. The study found that there are five factors which influence job and work attitude. These are satisfaction, independency, teamwork, freedom of expression and supervisory relationship. All these factors are significantly positive related to dependent variable job and work attitude.
Statistical measurement of service quality in Tanzania industries: A case of Said Salim Bakhresa & Co Ltd
(Macrothink Institute, 2012) Ismail, A.; Josephat, P.
The study aimed to use statistical techniques to measure quality of services produced by Said Salim Bakhresa & Co Ltd. The study was conducted among wholesalers and bakeries who sell wheat flour produced by the company. These were selected from four different locations representing the major towns where the wheat flour and its products are widely consumed. These are Dar es Salaam, Morogoro, Arusha, Moshi and Tanga. Sample size for the study was 434. The study employed the cross-sectional study design and prestructured questionnaire was used to collect data. Factor analysis and regression analysis are statistical techniques performed. From eleven attributes outlined by ISO: 9000: 2008, the factor analysis formed four components: product quality; packaging; timeliness and promptness; and customer care. The findings show that all the components achieved good quality level because all have quality scale index less than 2.99. Regression analysis was adopted to generate ISO-Quality model, model shows that among the four components of qualities, two components (product quality and customer care) are statistically significant related with the company being ISO certified. In general product quality and packaging seem to perform better than the rest of the components.
Group acceptance sampling plans for resubmitted lots for life tests based on half logistic distribution
(Renmin University of China, 2014) Rao, Srinivasa G.; Rao, Srinivasa B.
In this article, a Half Logistic Distribution (GASP) for lot resubmitting is developed to ensure quality of the product lifetime assuming that the product’s lifetime follows the half logistic distribution. The parameters of the GASP are determined by satifying the specified producer’s and consumer’s risks according to the experiment termination time and the number of testers. A comparison between this proposed group sampling and the ordinary group sampling plan is discussed. This proposed plan is justified with an illustration.
Quark star model with charged anisotropic matter
(Springer, 2014) Sunzu, J. M.; Maharaj., S. D.; Ray, S.
We find two new classes of exact solutions to the Einstein-Maxwell system of equations. The matter distribution satisfies a linear equation of state consistent with quark matter. The field equations are integrated by specifying forms for the measure of anisotropy and a gravitational potential which are physically reasonable. The first class has a constant potential and is regular in the stellar interior. It contains the familiar Einstein model as a limiting case and we can generate finite masses for the star. The second class has a variable potential and singularity at the center. A graphical analysis indicates that the matter variables are well behaved.
Some simple models for quark stars
(Springer, 2014) Maharaj, S. D.; Sunzu, J. M.; Ray, S.
We find two new classes of exact solutions for the Einstein-Maxwell equations. The solutions are obtained by considering charged anisotropic matter with a linear equation of state consistent with quark stars. The field equations are integrated by specifying forms for the measure of anisotropy and a gravitational potential which are physically reasonable. The solutions found generalize the Mark-Harko model and the Komathiraj-Maharaj model. A graphical analysis indicates that the matter variables are well behaved.
Asymptotic behavior of solutions of matrix lyapunov integro differential equations
(Korean Journal Publishing Service, 2014) Sarma, Goteti V.; Hugo, Alfred
The asymptotic behavior of solutions of Lyapunov type matrix Volterra integro differential equation, in which the coefficient matrices are not stable, is studied by the method of reduction.
Knowledge and perception on tuberculosis transmission in Tanzania: Multinomial logistic regression analysis of secondary data
(2014) Ismail, A.; Josephat, P.
Tuberculosis (TB) is one of the most important public health problems in Tanzania and was declared as a national public health emergency in 2006. Community and individual knowledge and perceptions are critical factors in the control of the disease. The objective of this study was to analyze the knowledge and perception on the transmission of TB in Tanzania. Multinomial Logistic Regression analysis was considered in order to quantify the impact of knowledge and perception on TB. The data used was adopted as secondary data from larger national survey 2007-08 Tanzania HIV/AIDS and Malaria Indicator Survey. The findings across groups revealed that knowledge on TB transmission increased with an increase in age and level of education. People in rural areas had less knowledge regarding tuberculosis transmission compared to urban areas [OR=0.7]. People with the access to radio [OR=1.7] were more knowledgeable on tuberculosis transmission compared to those who did not have access to radio. People who did not have telephone [OR=0.6] were less knowledgeable on tuberculosis route of transmission compared to those who had telephone. The findings showed that socio-demographic factors such as age, education, place of residence and owning telephone or radio varied systematically with knowledge on tuberculosis transmission.
New models for quark stars with charge and anisotropy
(2014) Sunzu, J. M.
We find new classes of exact solutions for the Einstein-Maxwell field equations. The solutions are obtained by considering charged anisotropic matter with a linear equation of state consistent with quark stars. The field equations are integrated by specifying forms for the measure of anisotropy and one of the gravitational potentials which are physically reasonable. A general feature of our models is that isotropic pressures are regained when certain parameters vanish; this behaviour is missing in most previous treatments. Particular models found in our results generalize the models of Mak and Harko, Komathiraj and Maharaj, Misner and Zapolsky, and the earlier results of Einstein. The graphical and physical analyses indicate that the gravitational potentials, the matter variables, the electric field and the mass are well behaved. In performing physical analysis we regain masses and radii of stellar objects consistent with observations. It is also shown that other masses and radii may be generated which are in acceptable ranges consistent with observed values of stellar objects. In particular we have established that our model is consistent with the stellar object SAXJ1808.4-3658. A study of the mass-radius relation indicates the effect of the electromagnetic field and anisotropy on the mass of the relativistic star.
Charged anisotropic models for quark stars
(Springer, 2014) Sunzu, J. M.; Maharaj, S. D.; Ray, S.
We perform a detailed physical analysis for a class of exact solutions for the Einstein-Maxwell equations. The linear equation of state consistent with quark stars has been incorporated in the model. The physical analysis of the exact solutions is performed by considering the charged anisotropic stars for the particular nonsingular exact model obtained by Maharaj, Sunzu and Ray. In performing such an analysis we regain masses obtained by previous researchers for isotropic and anisotropic matter. It is also indicated that other masses and radii may be generated which are in acceptable ranges consistent with observed values of stellar objects. A study of the mass-radius relation indicates the effect of the electromagnetic field and anisotropy on the mass of the relativistic star
Analysis of effects of agriculture intervention using propensity score matching
(Macrothink Institute, 2015) Josephat, Peter; Likangaga, Rose
Nowadays the agriculture extension programme s are practiced in many parts of the world. There is a mixture of results about the effects of agriculture intervention programmes. The literature shows that the interventions are ineffective and have limited diffusion. On the other side, it shows that interventions are effective. Following different arguments about the effects of agriculture extension, this paper adopted Propensity Score Matching (PSM) to analyze the effects of District Agricultural Sector Investment Project (DASIP) using agriculture data. The study was conducted in rural Tanzania areas. It covered five regions namely Kagera, Mwanza, Mara, Simiyu and Kigoma. The study focused on agro ecological zone where corn is cultivated. Two methods which are questionnaire administration and direct oral interview were used to collect primary data. The collection of data using the questionnaire was done from both participants (359) and non participants (519). Before running the independent t test, the estimation of propensity score was done using Logistic regression. Thirteen confounding variables were used to estimate propensity scores.The effects of the intervention were analysed by considering four items namely the earnings from corn production, value of livestock owned value of household assets owned, and value of farm assets owned. The results show that none of the four factors had significant result as the p values are greater than 0.05. This implies that the earning between farmers participating in DASIP are not significant different from those who do not participate in the programme. The study recommends that the group activities should last longer rather than changing them from time to time.
Thermal radiation and viscous dissipation effects on MHD heat and mass diffusion flow past a surface embedded in a porous medium with chemical reaction
(JS Publication, 2016) Reddy, B. P.; Sunzu, J.
The present paper deals with thermal radiation effects on the transient hydro-magnetic natural convection ow past a vertical plate embedded in a porous medium with mass discussion and fluctuating temperature about time at the plate, by taking account the heat due to viscous dissipation in the presence of chemical reaction. The governing equations are solved numerically by Ritz finite element method. The effects of various parameters entered into the equations of momentum, energy and concentration are evaluated numerically and plotted graphically, while numerical values of variations in skin-friction, rate of heat transfer in terms of Nusselt number at the plate are presented in tabular form. The results of the study are discussed
New exact models for anisotropic matter with electric field
(Springer, 2017) Sunzu, J. M.; Danford, P.
We generate two new exact models for the Einstein–Maxwell field equations. In our models, we consider the stellar object that is anisotropic and charged with linear equation of state consistent with quark stars. We have a new choice of measure of anisotropy that is physically reasonable. It is interesting that in our models we regain previous isotropic results as special cases. Isotropic exact solutions regained include models by Komathiraj and Maharaj; Mak and Harko; and Misner and Zapolsky. We can also obtain particular anisotropic models obtained by Maharaj, Sunzu, and Ray. The exact solutions corresponding to our models are found explicitly in terms of elementary functions. The graphical plots generated for the matter variables and the electric field are well behaved. We also generate relativistic stellar masses consistent with observations.
New stellar models generated using a quadratic equation of state
(2018) Sunzu, J. M.; Thomas, M.
We obtain new regular exact solutions to the field equations for uncharged relativistic stellar objects with vanishing pressure anisotropy. We assume a quadratic equation of state and a choice of measure of anisotropy and a metric function defining one of the gravitational potentials. In our exact models, we regain anisotropic and isotropic results generated by other researchers as a special case. It is interesting that our results are in agreement with Minkowski space–time and earlier Einstein models. The physical analysis of the plots reveals that the gravitational potentials and matter variables are well behaved in the stellar interior. Using our model, we generate finite relativistic stellar masses which are consistent with the astronomical objects previously found by other researchers.
Social determinants and attitudes of women on empowerment through microfinance institutions
(Macrothink Institute, 2018) Josephat, P. K.; Fulment, A. K.; Matunga, B. N.
Empowerment is a process, and it does not occur automatically. This has necessitated several studies to have different findings about the evidence for women empowerment. This is because empowerment is a continuous and constantly evolving process. This necessitates investigation of the factors which determine women empowerment in specific areas. This paper examined social factors which determine women empowerment in Kondoa District. Moreover, it establishes the level of attitude towards women empowerment. To determine factors and attitudes towards women empowerment, a survey was done at the household level for both women who are members and those who are not members of Microfinance Institutions in Kondoa District. A purposeful method was used to obtain a sample of 415 women involved in this study whereby 214 were members and 201 were nonmembers of financial institutions. Both qualitative and quantitative methods were utilized to collect and analyse data. Eight factors were analyzed to establish their association with women empowerment. Out of the eight factors, only five factors which include marital status [OR = 1.207], level of education [1.122], number of years lived in the area (residence) [1.018], microfinance membership [2.462] and residence area (urban) [1.008] were positively associated with women empowerment. The women’s attitude towards their empowerment is positive contrary to most men. The study recommends women to work hard with financial support received as they are key players for their success.
Estimation of stress–strength reliability from exponentiated inverse rayleigh distribution
(World Scientific Publishing Company, 2019) Rao, G. S.; Mbwambo, S.; Josephat, P. K.
This paper considers the estimation of stress–strength reliability when two independent exponential inverse Rayleigh distributions with different shape parameters and common scale parameter. The maximum likelihood estimator (MLE) of the reliability, its asymptotic distribution and asymptotic confidence intervals are constructed. Comparisons of the performance of the estimators are carried out using Monte Carlo simulations, the mean squared error (MSE), bias, average length and coverage probabilities. Finally, a demonstration is delivered on how the proposed reliability model may be applied in data analysis of the strength data for single carbon fibers test data.
Estimation of reliability in a multicomponent stress–strength system for the exponentiated moment-based exponential distribution
(Multidisciplinary Digital Publishing Institute, 2019) Rao, Srinivasa G.; Bhatti, Fiaz Ahmad; Aslam, Muhammad; Albassam, Mohammed
A multicomponent system of k components with independent and identically distributed random strengths X 1, X 2 , … X k , with each component undergoing random stress, is in working condition if and only if at least s out of k strengths exceed the subjected stress. Reliability is measured while strength and stress are obtained through a process following an exponentiated moment-based exponential distribution with different shape parameters. Reliability is gauged from the samples using maximum likelihood (ML) on the computed distributions of strength and stress. Asymptotic estimates of reliability are compared using Monte Carlo simulation. Application to forest data and to breaking strengths of jute fiber shows the usefulness of the model.
Total electron content prediction model using the artificial neural networks over the Eastern Africa Region
(College of Natural and Applied Sciences, University of Dar es Salaam, 2019) Sulungu, Emmanuel D.; Uiso, Christian BS
In this paper, development of a model using NN technique for prediction of GPS TEC over the Eastern Africa region is presented. TEC data was obtained from the Africa array and IGS network of ground based dual-frequency GPS receivers from 18 stations within the East African region. It covers approximately the area from ~2.6°N to ~26.9°S in magnetic latitudes and from ~95°E to ~112oE in magnetic longitudes. The input layer of the developed model consisted of seven neurons which were selected by considering the parameters that are known to affect the TECv data. The results showed that when the number of hidden layer neurons surpassed about 18, the RMSEs were noted to continuously increase indicating poor predictions beyond this number. The RMSE at this point was observed to be about 5.2 TECU which was lowest of all. The errors and relative errors were fairly small. Developed NN model estimated GPS TECv very well compared to IRI model. It is established in this study that, the IRI electron density at F2 peak (NmF2) gives good GPS TECv prediction when added as an input neuron to the NN.

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