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Effect of phase-equilibrium uncertainties on the process design of selected C2 and C3 alcohol separation systems: a Monte Carlo approach by Burger, Leon
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Page will reload when a filter is selected or excluded.- Assessment 2 results 2
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- Reliability indices are considered to be reasonable and logic ways to judge the performance of an electric power system. Reliability indices which are proposed by the IEEE are used to evaluate the performance of selected distribution systems on the national grid. Ten years of outage data (1998 - 2007) from seven selected distribution systems on the national grid were used as case studies in this research work. A generalized model is developed for a quantitative evaluation of relative indices of the national grid system. The development of the model stated with identification of the system reliability indices and estimating the contributions of system indices to the failure rate of the selected distribution system on the national grid. The computed system reliability indices are used as input parameters for the generalized model. Relative CAIDI index is computed by simulation using MATLAB 7.7 which automatically generates the graph of the relative CAIDl against names of feeders. The percentage average relative CAIDls for Ibadan, Port-Harcourt and Benin distribution systems are 71.86%, 52.79% and 75.79% respectively, thus, average reliability levels. Ilorin, Ikeja, Kaduna and Kano distribution systems have percentage average relative CAIDls of 11.95%, 39.76%, 40.17% and 41.08% respectively with poor reliability levels. With the aid of curve fitting (cf) tools, two distinct model equations were developed from which a generalized model is formulated for a quantitative evaluation of reliability indices of the national grid. The generalized model is a polynomial function whose order depends majorly on the level of industrialization of the distribution systems and the number of distribution feeders. 2 results 2
- Wellbeing 2 results 2
- A large number of hetero-aromatic and carbonyl molecules are useful in pharmaceutical and dye industries. Studies of their transition dipole moment (∆μ) and transition polarizability (∆α) are important because they determine their solubility and usefulness. Experimental determination of these parameters and other electronic properties such as oscillator strength (f) using Solvatochromic Shift Equations (SSE) has proved to be unreliable. This is due to the large spread in their reported values and the overlapping of the electronic transition bands for a given molecule. This study was designed to modify the SSE in improving its reliability, and to computationally determine the photophysical properties of some hetero-aromatic and carbonyl compounds with a view to studying the extent of overlap of the electronic transition bands. The ultra-violet spectra of 2,3-diphenylcyclopropenone; 9,10-phenanthrenequinone; Furan-3,4-dicarboxylic acid; 3,4-diphenylthiophene; 3,4-dicarboxylic-2,5-diphenylthiophene and benzo[b]thiophene in the wavenumber range (25,000 - 52,631) cm-1, in solvents of different polarities at concentrations range of 10-6 - 10-5 M were measured at 25oC. These compounds were selected for the modified SSE due to the variation in their structures. The magnitudes of f in solution (fs) and in vapour phase (fv) were calculated using the Onsager-Abe reaction field model equations. The frequencies of electronic transitions in various solvents were used to characterise the observed bands. The SSE was modified by incorporating the molecular ground state polarizability (α), the molar refraction of each compound, Einstein coefficient and stark term. Estimation of the Δµ and Δα of these compounds were determined using the modified SSE. The electronic properties: f, number of transitions, the frontier orbitals energy gap (ΔELUMO-HOMO) and associated parameters such as: Ionization Potential (IP) and global hardness (ƞ) of the optimized structures of the molecules were calculated based on Time-Dependent Density Functional Theory using Becke’s three parameter with Lee-Yang-Parr modification and 6-31G* basis set. The spectra of these compounds gave a range of one to five bands designated as S0-S1, S0-S2, S0-S3, S0-S4 and S0-S5 in order of increasing energy. The magnitudes of fs and fv for the observed bands increased with increasing solvent polarities and were within the range 3.2x10-4 - 1.78 and 3.1x10-4 - 1.33 for hetero-aromatics; 1.4x10-3 - 1.52 and 1.3x10-3 - 1.23 for carbonyls. Similar trends observed for the experimental values of Δµ and Δα indicated that the more a transition is allowed, the greater the probability Δµ being larger than zero. The positive values of Δµ (5.7x10-3 - 1.73D) and Δα (8.0x10-5 - 5.5Å3) for hetero-aromatics; Δµ (3.7x10-2 - 1.23D) and Δα (4.8x10-4 - 0.95Å3) for carbonyls indicated substantial redistribution of the π-electron densities in more polar excited state than the ground state. The ΔELUMO-HOMO were (3.19 - 4.09eV) and (4.36 - 5.43eV) for carbonyls and hetero-aromatics respectively. The IP and ƞ increased as solvent polarity increased, suggesting high stability of these compounds in polar solvents. The modified equation is better in the estimation of transition dipole moment and transition polarizability. The energy gaps and associated parameters suggested strong activity of the molecules and minimal overlapping of the transition bands. 1 results 1
- Abstract: The demand for University education in Nigeria has led to an increase in undergraduate population and this comes with various problematic conditions with regards to university accommodation, available basic infrastructure and facilities. The resultant effect is manifested in overcrowded residential halls and rooms. Against this backdrop, this study investigated the correlation between overcrowding and environmental safety and wellbeing in female undergraduate halls of residents in the University of Ibadan, Nigeria. Four research questions and two hypotheses guided the study. Descriptive survey research design was adopted and a sample of six hundred and fifty five (655) was proportionately drawn from the residential female undergraduate population of 3274. A questionnaire with reliability coefficient of 0.87 was used for data collection. The results showed that 87.7% of the female undergraduates perceived their rooms to be overcrowded. Findings on environmental safety showed that apart from fire extinguisher, other safety facilities and equipment are either not readily available or are not adequate in all the halls of residence. The result of the hypothesis showed a strong negative relationship between overpopulation and environmental safety and wellbeing. In recommendation, more halls of residents should be built to meet up with the increase in female undergraduate enrolments to Nigerian universities. Environmental safety issues of residential undergraduates must be taken seriously by providing functional safety facilities and equipment to make the halls more secure. 1 results 1
- ActiveX 1 results 1
- Adolescent 1 results 1
- Adolescents 1 results 1
- Adsorption 1 results 1
- Affect Recognition 1 results 1
- Ageing is a gradual process that begins from birth till death. It is characterized by the persistent wearing away and repair or replacement activities of the body but more remarkable at old age. The study assessed the old age health problems of old age people in Ido Usi Local Government Area of Ekiti state. Stratified and purposive sampling technique was used to select a sample of200 participants comprising of both male and female aged 60 years and above. As self developed and validated structured questionnaire was used for data collection. Reliability coefficient of 0.72 was obtained for the instrument using crombach's alpha coefficient (r). The data was analyzed using descriptive statistics of frequency counts, percentages and chi-square x2 at 0.05 alpha level. The result showed that old age people have a decrease in biological functioning of their body system as they suffered defective symptoms in their eye sight, bone and muscle, skin and hair, sex organs response, diabetes and insomnia. Suggestion was made on coping strategies for successful and active ageing. 1 results 1
- As important as attitude scales are in the teaching and learning domain, scales on affective traits are relatively limited especially those developed by using IRT based models. This study developed and validated an instrument-the Students Attitude to Economics Scale (SATES), using the IRT model. At the initial exploratory stage, data obtained from a sample of973 high school economics students were subjected to parallel and full information item factor analyses with multidimensional graded response model. This was based on the number of dimensions identified under parallel analysis to identify the interpretable factors underlying the scale. A total of 14 items of the initial 55 constructed items emerged with four factors named; difficulty of economics, performance in economics, benefits of economics and pedagogy of economics. To assess the construct validity of the SATES, the differential functioning of the items on the scale, with respect to the sex of the respondents, were assessed. The results showed that all the 14 items had insignificant chi-square value (p > 0.05). Meaning that all the 14 items that survived item analysis functioned similarly among males and females, hence were valid items. To estimate the reliability of the 14-item SATES, the responses of the testees to the 14 items were subjected to empirical reliability analysis, an IRT based reliability estimate. The outcome revealed a reliability estimate of 0.75, 0.73, 0.84, and 0.79 for each of the four factors respectively, hence 0.78 for the SATES. To cross-validate the 14-item SATES, it was administered to another sample of 1,274 high school economics students, and the invariance of the scale was assessed. To achieve this, response was subjected to multiple group multidimensional item response theory analyses. This provided evidence of the construct validity of the instrument, indicating that the instrument is a valid and reliable tool for measuring senior secondary school students' attitude towards economics. 1 results 1
- Attitude scale development 1 results 1
- Attitude to high school economics 1 results 1
- Auditory perception 1 results 1
- Background: Childhood and adolescent depression is common and often persists into adulthood with negative implications for school performances, peer relationship and behavioural functioning. The Child Depression Inventory (CDI) has been used to assess depression among adolescents in many countries including Nigeria but it is uncertain if the theoretical structure of CDI appropriately fits the experiences of adolescents in Nigeria. This study assessed varying theoretical modelling structure of the CDI in a population of apparently healthy adolescents in Benue state, Nigeria Methods: Data was extracted on CDI scale and demographic information from a total of 1, 963 adolescents (aged 10–19 years), who participated in a state wide study assessing adolescent psychosocial functioning. In addition to descriptive statistics and reliability tests, Exploratory Factor Analysis (EFA) and Confirmatory Factor analysis (CFA) were used to model the underlying factor structure and its adequacy. The suggested new model was compared with existing CDI models as well as the CDI’s original theoretical model. A model is considered better, if it has minimum Root Mean Square Error of Approximation (RMSEA <0.05), Minimum value of Discrepancy (CMNI/DF<3.0) and Alkalike information criteria. All analyses were performed at 95% confidence level , using the version 21 of AMOS and the R software. Results :Participants were 14.7±2.1 years and mostly male (54.3%), from Monogamous homes (67.9%) and lived in urban areas (52.2%). The measure of the overall internal consistency of the 2-factor CDI was α = 0.84. The 2-factor model had the minimum RMSEA (0.044), CMIN/DF (2.87) and least AIC (1037.996) compared to the other five CDI models. Conclusion: The child depression inventory has a 2-factor structure in a non-clinical general population of adolescents in Nigeria. Future use of the CDI in related setting may consider the 2-factor model. 1 results 1
- Background: The testes are responsible for the production of spermatozoa and testosterone in man. Relaible and accurate determination of testicular volumes is of great potential benefit in evaluation of patients with a variety of disorders affecting testicular growth, development and function. Ultrasonography (USS) provides a good and reliable tool for determining testicular volume when objective, accurate and reproducible measurements are required. This can be done in an easy and patients friendly manner. USS is readily available, cheap and does not invovle the use of ionizing radiation; hence its suitability in neonates.Aim:To determine the normal value for mean testicular volume in neonates using ultrasonography and to correlate testicular volume with weight, gestational age, and length as well as body mass index, so as to have a baseline reference value which will aid in prompt identification of neonates with testicular abnormalities for further evaluation and timely intervention. Design of the study: A multi-centre prospective cohort study. Study Setting: Radiology departments of the Univeristy College Hospital, Adeoyo General hospital and Eleta Catholic Hospital, Ibadan, Southwestern Nigeria. Materials & Methods: A total of 411 healthy male neonates had testicular ultrasound performed in the labor wards and post natal wards of the University College Hospital, Adeoyo General Hospital and Eleta Catholic Hospital, Ibadan, Nigeria. Testicular mean volume was obtained using the Lambert formular (length x width X height x 0.71). The statistical package for the Social Sciences (SPSS) for windows version 17.0 was used to analyze the data obtained. Results: The mean left testicular volume in this study was 0.276cm3+ 0.08925 while the mean right testicular volume was 0.278cm3+0.09233. The overall mean testicular volume in neonates was 0.28+ 0.09cm3no significant difference between the right and the left testes (p=0.000). There is a weak but statistically significant positive correlation between testicular volume and the birth weight, height, and body mass index but no correlation between the testicular volume and the gestational age at delivery. Conclusion: This study showed that the mean testicular volume was 0.28+0.09ml with no significant difference between the right and the left testes. There was a positive correlation between the birth weight, height and the body mass index and the volume of the right and the left testes but no correlation between the testicular volume and the gestational age of the neonates 1 results 1
- Based on the initial research on the suitability of RHA in partial replacement of cement in HSC production, it was observed that between 10 - 20% replacement by weight of cement with RHA shows potential for use in the production of HSC based on their compressive strength. However, However, the use of compressive strength criteria only as a determinant in High Strength Concrete (HSC), especially in RHA-Cement blend concrete, has shown its inadequacies. Fracture Mechanics is a reliable experimental/analytical tool that has not been adequately used in the study of RHA-based HSC. Thus, the need to study its fracture mechanics parameters such as Crack Tip Opening Displacement (CTODC) test and Stress Intensity Factor (KSIC) to understand the behaviour of the RHA-based HSC to fracture toughness which is an indication of the strength of concrete when subjected to loading. Milled samples of the RHA were used in the preparation of RHA- Cement blends with the cement being replaced at 0%, 10% and 20% by cement weight. The 0% replacement served as a control for the experiment. 36 cubes of HSC with an expected compressive strength of 60MPa respectively were produced; 12 cubes for each percentage replacement aimed at affirming the compressive strengths were within the expected 60 MPa value. Then same mix design was used to prepare 78 beams (18, 30 and 30 for 0%, 10% and 20% RHA-Cement blend HSC) were prepared and subjected to experimental Fracture Mechanics three-point bending tests (TPBT) while the peak load for each beam before failure were recorded. The recorded peak loads were used to develop function via numerical computational and statistical models to determine the and values for the concrete. Based on the numerical analysis done, there was a progressive increase in CTODC and KSIC with an increase in RHA content in the concrete mixes with 20% having the highest C T OD c and Kfc (1 .4 1 9 7 M P aVm and 0 .0 3 1 7 m m) values compared to the control and the 10% RHA. Thus, it implies 20% RHA-cement blended HSC has more resilence compare to the 10% RHA. 1 results 1
- Basic Education 1 results 1
- Bentonite 1 results 1
- Challenges 1 results 1
- Childhood trauma 1 results 1
- Children and Adolescents 1 results 1
- Community plantation 1 results 1
- Confirmatory Factor analysis 1 results 1
- Confirmatory factor analysis 1 results 1
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