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The evaluation of bacteriocins and enzymes for biopreservation of wine by Du Toit, Corina
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Page will reload when a filter is selected or excluded.- Earth Sciences 2 results 2
- General 2 results 2
- 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
- " Flow variability of ephemeral rivers due to spatial and temporal distribution of rain fall and unregulated exploitation of water resources is a major cause of severe water supply shortages. With appropriate conservation planning of surface waste resources through hydrological modeling, timing of extraction of large volume without adverse effects on downstream requirement can be predicted. This study attempts to develop water balance components for evaluating flow characteristics essential for conservation planning of ephemeral streams. Daily meteorological data spanning 1973-2006, obtained from the International Institute of Tropical Agriculture, Ibadan weather station were used in developing predominant water balance model components of Ona Stream. Daily infiltration values were obtained using Crawford and Linsley’s model and interflow based on soil moisture levels. Data were statistically analyzed and developed models validated using 10 years meteorological data. Analyses showed that 93.4, 91.5 and 55.0 % variability in runoff was due to precipitation, groundwater storage and interflow respectively. Precipitation, interflow and groundwater storage were significant while evapotranspiration was insignificant (P.0.05) for runoff prediction. The water balance models simulated acceptable hydrologic processes such as interflow and groundwater storage which are generally difficult to measure directly. The R2 values obtained from validation range from 0.79 to 0.99. The water balance model thus improved the reliability of streamflow computation and other flow characteristics of the ephemeral Ona stream. It would appear that the ephemeral streamflow investigated depended more on the magnitude of precipitation interflow and groundwater flow while evapotranspiration (a major source of water loss in hydrologic water balance model) has relatively little effect on streamflow characteristics." 1 results 1
- "The fact that the drive parameters space of harmonically excited pendulum consist of mix parameters combination leading to different dynamics phenomena including chaotic and periodic responses is a strong motivation for this study aim at estimating the peak frequency that favour chaotic response. Simulation of pendulum and estimation of the average Lyapunov exponents by Grahm Schmidt Orthogonal rules at parameter nodal points selected from damp quality (2.0≤q≤ 4.0). excitation amplitude (0.9≤g ≤1.5) and drive frequency (0.5 ≤ ωD≤1.0) were effected using popular constant time step Runge-Kutta schemes (RK4, RK5 and RK5B) from two initial conditions through transient and steady periods. The impact of resolution on the measure of percentage of parameters combination leading to chaotic response (PPCLCR) was examined at resolution levels (RI to R5) for increasing drive frequency. The validation cases were from those reported by Gregory and Jerry (1990) for (ώᶹ,q,g≡ 2/3,4,1.5) and (ωυq,g≡ 2/3,4,1.5) simulated from (0. 0) initial conditions. Corresponding validation results compare well with reported results of Gregory and Jerry (1990). The estimated peak frequency (0.6 radian /s) is the same across studied resolutions initial conditions and Runge-Kutta schemes. The peak value of PPCLCR is 69.5. 69.4 and 69.4 respectively for RK4. RK5 and RK5B at initial conditions (0. 0). When initial conditions is (I. 0) the corresponding PPCLR value changes in significantly to 69.6. 69.7 and 69.6 for RK4, RK5 and RK5B. Therefore affirms the utility and reliability of Lyapunov exponent as chaotic response identification tool. " 1 results 1
- A Monte Carlo simulation is employed to investigate the sensitivity of simultaneous equation different levels of correlation between random deviates. Three arbitrary levels of correlation between pairs random deviates were assumed. Three small sample sizes were used in this experiment, N = 15, N=25 and N 40 each replicated 100 times. A number of factors should be taken into account in choosing an method Although system methods are asymptotically most efficient in the absence of violation of independence of random errors, system methods are more sensitive to any kind of error than single equation methods. In practice, models are never perfectly specified nor are they completely free of correlated random deviates. It is a matter of judgment whether the correlation is strong enough to warrant avoidance of system methods. As sample size increases, the TAB for all the estimators decreased consistently except for FIML. OLS, 2SLS, LIML and FIML are remarkably insensitive to the choice of triangular matrices (P1 and P2) when using TAB to judge their performances. Best RSS estimates of 2SLS, LIML, and 3SLS found in the feebly correlated region 1 results 1
- Abattoir 1 results 1
- Achievement and Attitude to special education 1 results 1
- Adaptive Gaussian Quadrature 1 results 1
- Air contioner, 1 results 1
- Air-conditioning system design and ducting analysis has over the years been an aspect of Engineering, which even though has developed greatly, yet it brings about very tedious tasks of analysis, low level of accuracy, and a lot of time input in carrying out its analysis manually. This work makes provision for the use of a software package, designed for ducting analysis. It has the capability of handling analysis for buildings having as much as nine (9) floors, with each floor having up to twenty (20) rooms. The report gives an account of the method used and the programming aspect of the package for ducting analysis. The thermal analysis of a building forms the basis for the equipment selection in terms of capacity of the cooling equipment, quantity of dehumidified air required and the type of system to be recommended. The estimated air quantity is then used in carrying out the analysis of the system. The package has been designed in such a way that results of analysis made could be printed out for use. Also, it can be easily used on any computer that has a floppy drive for its installation, and has been produced using Visual Basic 6.0. it would be very useful for professionals, as it can carry out analysis which might take hours to develop in few seconds, and also, can be used in higher institutions as teaching aid to INSTRUCT Engineering students. 1 results 1
- Akaike’s information criteria 1 results 1
- Basic Science 1 results 1
- Basic Science is a core subject at the basic education level in Nigeria. It is taught to lay foundation for future subjects, such as Biology, Chemistry and Physics. Evidence abound that students dislike, fear and therefore fail the senior secondary science subjects due to inadequate exposure to practical works and skills at the basic education level. Previous studies largely focused on factors affecting teaching and learning of Basic Science practical without emphasis on intervention through regular conduct of laboratory experiments in the subject. This study, therefore, determined the effects of Simulated Laboratory (SL) and Enriched Laboratory Guide Material (ELGM) experiments on students’ achievement and acquisition of Science Process Skills (SPS) in Basic Science in Oyo State, Nigeria. The moderating effects of gender and future career interest in science were also examined. Bruner’s constructivist and Kolb’s experiential learning theories provided the framework, while the pretest-posttest control group quasi-experimental design with a 3x2x2 factorial matrix was adopted. Three local government areas were randomly selected from each of Ibadan (Ibadan South-East, Ibadan South-West, Ibadan North) and Oyo (Afijio, Oyo-East, Oyo-West). Six co-educational public secondary schools were purposively selected based on availability of functional computer and science laboratories. Six randomly selected intact classes of junior secondary three students (130 males and 147 females, ±17 years) were randomly assigned to SL (110), ELGM (60) and Conventional (Expository) Laboratory - CEL (107). The instruments used were: Achievement test in Basic Science (r=0.87), Science process skills test in Basic Science (r=0.72) and Future career interest in Science questionnaire (r=0.99). The treatments lasted seven weeks. Data were analysed using Analysis of covariance and Scheffé post-hoc test at 0.05 level of significance. Treatments had significant main effect (F(2,264)=25.88; partial η2=.16) on students’ achievement in Basic Science. Participants in the ELGM group had highest achievement mean score (24.91) followed by CEL (24.77) and SL (19.40). Future career interest in science had significant main effect (F(1,264)=4.08; partial η2=.02) on students’ achievement in Basic Science. Participants in the Science-Related (SR) group had higher achievement mean score (23.87) than Non-Science Related (NSR) group (22.18). Treatments had significant main effect (F(2,264)=25.51; partial η2=.16) on students’ acquisition of SPS in Basic Science. Participants in the SL group had highest SPS mean score (15.00) followed by ELGM (14.66) and CEL (12.59). Future career interest in science had significant main effect (F(1,264)=17.62; partial η2=.06) on students’ acquisition of SPS in Basic Science. Participants in the SR group had higher SPS acquisition mean score (14.81) than NSR (13.36). There was no significant main effect of gender on students’ achievement and acquisition of SPS in Basic Science. There were no significant two-way and three-way interaction effects on students’ achievement and acquisition of SPS in Basic Science. Enriched laboratory guide material experiment was more effective in enhancing achievement while Simulated laboratory experiment was more effective on acquisition of science process skills. The two modes of laboratory experiments should be adopted for improved achievement and acquisition of science process skills in Basic Science 1 results 1
- Bayesian estimation 1 results 1
- Broadcast Storm 1 results 1
- Broadcasting 1 results 1
- Chloride concentration 1 results 1
- Class level 1 results 1
- Clustered survey 1 results 1
- Coastal aquifer 1 results 1
- Coefficient of Performance 1 results 1
- Computer-simulated instructional strategy 1 results 1
- Cooling 1 results 1
- Correlation coefficient 1 results 1
- Counter-Based Scheme 1 results 1
- Curriculum Evaluation 1 results 1
- Data over-collection 1 results 1
- Due to the abstract nature of physics, many secondary school students have low interest and perform poorly in the subject. Literature showed that to stimulate students‟ interest, better conceptual understanding and achievement, there is the need to introduce computer-simulated experiments in physics practical classes. Previous studies on the use of computer-simulated experiments in physics practical activities have focused more on students in higher institutions than on secondary school students. This study, therefore, investigated the effects of computer-simulated instructional strategy on senior secondary school (SSS) students‟ interest and achievement in physics practicals in Imo State, Nigeria. It also determined the moderating effect of numerical reasoning ability (NRA)and perceptual reasoning ability (PRA). This study adopted a pretest-posttest, control group quasi-experimental design. Multistage random sampling was used to select 359 of intact classes of SSS II from six secondary schools from Owerri Educational Zone. Participants were randomly assigned to treatment groups: Computer-Simulated Experiment (CSE), Computer-Simulated and Hands-on Experiment (CSHE) and Conventional Hands-on Experiment (CHE). Treatment lasted eight weeks. Instruments were used: Physics Achievement Test (r =0.84), Students‟ Interest in Physics Questionnaire (r =0.85), Numerical Ability Test (r= 0.90), Perceptual Ability Test (r = 0.87), Practical Test (r = 0.84) and Software Package. Seven null hypotheses were tested at 0.05 level of significance. Data were analysed using MANCOVA. Treatment had a significant effect on students‟ achievement and interest in physics practical, (= 0.91, F (4,670) = 8.32, η2= 0.047). Also, treatment had a significant effect on students‟ achievement (F (2,336) = 14.76, p < 0.025, η2 = 0.081) but had no significant effect on interest. Students exposed to CSE performed slightly better ( ̅=38.67;SD=6.86) than those in CSHE ( ̅ = 38.56, SD = 6.85) and CHE ( ̅ = 33.37; S.D = 7.51). The NRA had asignificant effect on achievement and interest in physics practicals (= 0.96, F (4,670) =3.62, η2 = 0.021), Also, it had a significant effect on achievement, (F(2,336)=420,p<0.025,η2= 0.025) but none on interest. Students with low NRA students performed betterthan high and moderate ability students. The NRA had no effect on interest. Also, PRAhad a significant effect on students‟ achievement and interest in physics practicals (=0.95, F (4,670) = 4.84; η2 = 0. 028) as well as a significant effect on students‟ achievement (F(2,336) = 7.89, p <0.025, η2 = 0.045) but none on interest. Students with high PRA performed better ( ̅ = 38.19; S.D. = 8.62) than moderate ( ̅ = 37.56; S.D. = 6.91) and low ( ̅ = 24.49; S.D. = 6.35) abilities. There was a significant interaction effect of treatment and PRA on students‟ achievement and interest (= 0.95; F (8,670) = 2.21; η2 = 0.026). Computer-stimulated experiments enhanced students‟ conceptual understanding and achievement in physics; however, when combined with hands-on experiment, it became less effective. Therefore, curriculum planners and teachers should use the instructional strategy particularly for moderate perceptual ability and low numerical ability students. 1 results 1
- Dynamic model, 1 results 1
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