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The hydrodynamics of supercritical packed countercurrent columns by Franken, Hendrik Hermanus
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In situ denitrification on nitrate rich groundwater in South Africa by Israel, Sumaya
Published 2015Get full text
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Page will reload when a filter is selected or excluded.- Model 2 results 2
- Temperature 2 results 2
- Academic performance 1 results 1
- African catfish 1 results 1
- Artificial Neural Network 1 results 1
- Artificial Neural Network has been discovered as a better alternative to traditional models and that is why a model based on the Multilayer Perceptron algorithm was developed in this study. The appropriate number of hidden neurons that best modeled the academic performance of students was determined by the developed Network algorithm. Test data evaluation showed that Network Architecture 17-80 -1 was chosen among the numerous developed network architectures because of its model performances. The chosen network architecture gave the minimum value of Mean Square Error (MSE = 0.0718), minimum value of Network Information Criteria (NIC = 0.0743), maximum value of R- Square (R2=0.8975) and maximum value of Adjusted Network Information Criteria (ANIC= 0.8931). It was equally observed that there were patterns in the movement of hidden neurons against the model evaluation criteria. As the number of the hidden neurons appreciates the value of both MSE and NIC decreases down the plot, while that of ^-Square and ^MCvalues appreciate down the plot. The network was able to model the research problem with acceptable values judging from the model checking criteria considered in this work. Also the order of contribution of the predictor variables to the model was determined. 1 results 1
- Assimilation 1 results 1
- Bioavailability 1 results 1
- Climate variability 1 results 1
- Climate variability is indicated as anomalies in weather parameters such as rainfall and temperature. These are being influenced by greenhouse gas emissions such as carbon dioxide (CO2) and methane (CH4), amongst others. This variability is usually studied using General Circulation Models (GCMs) and empirical models obtained from analyses of data at synoptic weather stations. The GCMs give different predictions from model to model due to parameterisations of microprocesses embedded in them. Likewise, empirical models are often applicable to locations of studies and most stations in the tropics are yet to be analysed. Hence, this work was aimed at analysing and modelling both CO2 and CH4 concentrations over the entire tropics with a view to understanding their contributions to climate variability. Daily concentration data of CO2 and CH4 from the 12 stations, with minimum of 10-year data, within latitude 30oN and 30oS were obtained from World Data Centre for Greenhouse Gases, Japan. These data, between January 1996 and December 2005, were analysed using standardized anomalies, moving average and autocorrelation methods. Box-Jenkins iterative method which combines both moving average and auto regression analyses, was employed for modelling the concentrations (i) of the gases as a function of time. The suitability of the developed model was determined by comparing the predicted and measured monthly concentrations of these gases for the period January 2006 to December 2008. The standard deviations (i) of the concentrations of these modelled gases were correlated with Roy Spencer‟s tropical temperature anomaly data to ascertain their warming effect.The standardized anomalies showed seasonal variations and smoothening of these data by moving average revealed monotonic increase with time. The autocorrelation function showed that CO2 can be predicted with higher accuracy than CH4. The developed model was of the form:121111120)120(tctba for CO2 and 222222120)120(tctba for CH4, where ai, bi, c i and t represent the intercept, linear term coefficient, quadratic term coefficient and predictedmonth respectively. The mean annual concentrations calculated using the model for CO2 and CH4 in the northern hemisphere stations ranged from 381.5±0.3 to 384.3±0.3 ppm and 1793.5±1.4 to 1832.9±1.7 ppb respectively, while the measured values ranged from 382.9±0.2 to 384.5±0.2 ppm and 1787.3±1.4 to 1823.3±1.0 ppb respectively.Similar agreement was obtained between calculated and measured values for southern hemisphere stations. The correlation coefficient between predicted and measured concentrations of CO2 and CH4 for year 2006 to 2008 was 0.99 and 0.96 respectively. The i for CO2 and CH4 concentrations in northern hemisphere ranged from 0.3 to 0.9 and 0.5 to 3.3 respectively, while those in southern hemisphere ranged from 0.4 to 0.7 and 0.2 to 4.2 respectively. The i increased with climatic warming and had highest value for 1998, the warmest among the years considered. Concentrations of both CO2 and CH4 increased monotonically with time. The developed model predicted CO2 and CH4 concentrations adequately in the tropics and could also be used to predict their future concentrations and climate warming effectively. 1 results 1
- Climate-variability 1 results 1
- Commercial banks in Nigeria are more engrossed with profit maximization and as such they tend to neglect the importance of liquidity management. This eventually leads to financial indebtedness and consequently low patronage and deposit flight. This study examined the effect of liquidity management on profitability of commercial banks in Nigeria using data obtained from the financial statements of tier 1 banks over the period 1998 to 2018. The study employed the correlational research design and engaged the Johansen test with the vector error correction model to access the long run and short run relationship among the variables. The results of the Johansen test revealed at most two cointegrating equations among the variables, while result of vector error correction revealed a positive effect of liquidity on return on asset and return on equity but a negative effect on net profit margin. Results revealed a fairly stable trend in the liquidity and profitability indicators from 1998-2018 and concluded that banks controlled enough liquidity to serve their obligations. The study recommends that the central bank of Nigeria should maintain the regulation over the minimum liquidity of commercial banks as this affects their profitability 1 results 1
- Community participation 1 results 1
- Connected speech processes 1 results 1
- Connected speech processes (CSPs) account for sound modifications and simplifications in speech, while sociophonetics emphasises correlation between speech forms and social factors. Existing studies merely identified some CSPs that characterise Nigerian English (NE); studies that measure speakers' proximity to Standard British English (SBE) connected speech, especially in relation to social variation, are scarce. This study, therefore, investigated the incidence of assimilation, elision and liaison processes of SBE connected speech in NE with consideration for the region, gender and age of speakers. This is with a view to determining the level of NE speakers' approximation to or deviation from SBE. The study adopted generative phonology to explain NE speakers' application of or deviation from the SBE rules, and variability concept to show the correlation between CSPs and social factors. The participants, who ranged between ages 18-65, were 180 male and 180 female NE speakers with a minimum of 2-3 years post-secondary education. They were drawn, through stratified and purposive techniques, from four regions in Nigeria: north (120), west (80), east (80) and south-south (80). All participants produced semi-spontaneous speeches (SSS), containing 31 utterances and a short passage, into digital recording devices and filled 360 copies of a structured questionnaire. Two educated native speakers served as control. The recordings were transcribed and the scores analysed, using percentages, MANOVA and Bonferroni's Post-hoc test. Portions of the SSS of eight participants (representing the social variables) and one native speaker were analysed acoustically, using PRAAT speech analyser (version 5120). The overall incidence of the CSPs (assimilation, elision and liaison) of SBE for all categories of participants indicated 43.2% approximation and 56.8% deviation. However, incidence of each process varied. Three assimilation variants- regressive devoicing (99.2%), progressive devoicing (65.1%) and nasal assimilation (63.5%)- showed significant approximation to SBE, while four variants- progressive voicing (21.2%), voiceless alveolar stop assimilation (47.6%), voiced alveolar stop assimilation (3.2%) and yod coalescence (6.2%)- deviated significantly. Consonant elision, in all contexts, occurred significantly (61.5%), while the incidence of liaisonlinking /r/ (8.1%) and intrusive /r/ (2.9%)- was extremely low. The speech waveforms, formants structure and voicing bars on the participants' spectrograms, in most cases, displayed considerable deviation from SBE. In terms of social variation, the combined dependent variable (assimilation, elision and liaison) was significantly affected by gender (Pillai's Trace=0.07,F(3,342)=8.12,p<0.05,η2=0.07) and region (Pillai's Trace=0.11,F(9,1032)=4.29,p<0.05,η2=0.04), but not by age or their interactions. Gender had significant effect on elision F(1,344)=22.21;p<0.01,η2=0.06): males had higher mean performance (M=9.91;SD=2.84) than females (M=8.55;SD=2.58). Region was found to be significant in liaison F(3,344)=8.14;p<0.01,η2=0.07): Eastern participants (M=1.38;SD=1.44) had the highest mean score, followed by South-South (M=1.10;SD=1.22), Western (M=1.05;SD=1.16) and Northern participants (M=0.57;SD=0.94). The Bonferroni's Post-hoc results indicated that only Eastern and Northern participants differed significantly from each other. Nigerian English speakers' mastery of Standard British English connected speech processes, irrespective of gender and regional variation, manifested, overall, more deviation from than approximation to SBE. This suggests Nigerian English speakers' relatively low level of competence in Standard British English connected speech processes, and has implications for intelligibility 1 results 1
- Critical frequency (foEs) 1 results 1
- Data on different climatic elements, like monthly rainfall monthly mean relative humidity, monthly lowest relative humidity; monthly mean temperature, monthly mean maximum and minimum temperatures with their monthly extremes values and monthly mean prevailing wind speeds over Ibadan for the months of January through to December during the period of 1979 through to 2005 have been considered to study their variability and to determine the probabilistic extreme values of these elements. The probabilistic extremes values have been computed for 3 time scales: In 1 year out of 4 years, in 1 year out of 10 years and in 1 year out of 25 years- representing relative more frequent events, moderately extreme events and extreme events, respectively. 1 results 1
- Decent work agenda 1 results 1
- Decent work agenda, 1 results 1
- Elision 1 results 1
- Employment issues 1 results 1
- Employment issues. 1 results 1
- Equatorial electrojet 1 results 1
- Equinoctial maximum 1 results 1
- Equinox 1 results 1
- Extruder-development 1 results 1
- Fisheries and aquaculture contribute significantly to food security and livelihood; therefore, fish and fish products are projected as being among the most widely traded foods. Fish like other animals has requirement for essential nutrients in order to grow properly. Such essential foods are available in the wild for fish to forage extensively to meet their body needs. The variable factors such as climate change, environment, season of the year and location among others determines the abundance and search for these foods. These factors modifies aquatic environment and make it difficult for fish in the wild to forage adequately. Therefore, enough food in the form of artificial diet is required to furnish fish with the nutrients it need out of its natural environment for optimal growth. However, most of the challenges facing the formulation of feed are on the affordability, ready acceptability and bioavailability for fish optimal growth. Therefore, trace minerals which are needed in minute quantity at a time for the general health maintenance and growth of an animal offers a soft landing to this challenges; however, their deficiency perturbs the wellbeing of the fish. Zinc has been recognized to play a vital role in almost every aspect of living system either directly or indirectly. The biochemical components of fish diet that needs varying in terms of percent inclusion to render the protein in feed more bioavailable should be encouraged. The objectives of this study includes determination of the; required dietary zinc inclusion that is essential for juvenile African catfish Clarias gariepinus growth, serum biochemical profile of African catfish juveniles post feeding response to growth, and haematological responses of African catfish (Clarias gariepinus) to graded levels of zinc nutrient. Growth performance, serum biochemistry and physiological response to graded levels of practical dietary zinc fed to African catfish (Clarias gariepinus) juvenile were investigated. Water quality was monitored throughout the period of the study and the results showed that all parameters were within the required and tolerable ranges for catfish. The mean weight of fish fed dietborne zinc nutrients revealed that there were no significant differences in growth responses to graded levels of dietary zinc inclusions of 0, 5.46, 10.96, 16.40, 21.86 and 27.33mg Znkg-1 . The results for the mean weight revealed that there are no significant variations in mean weight since P>0.05. However the mean weight for the diet increased with respect to dietary zinc inclusion (Figure 1). The SGR, FCR, GFCE, F.I and RGR, also showed no significant variations among fish fed. The PCV revealed that there are no significant variations among the values for the fish fed with Diets 3, 4 and 5. The serum biochemistry revealed significant variations in the serum total protein (T,P) among fish fed on all the Diets, with the highest values in fish fed Diets 4 and the minimum values in fish fed Diet 2. Fish fed dietary zinc had slightly altered haematological and serum biochemistry in response to dietary zinc. 1 results 1
- Food security 1 results 1
- Food security is a function of a few variables such as technological input, capital, government policies and environmental (climate) factors. Good control of all these dependent variables except the last, and the thorough understanding of the last can take the nation to food security level. Possible ways of controlling the first three variables (technological input, capital, government policies) are suggested. To have thorough understanding of the climate factors, time series analysis of climate variables precisely temperature and precipitation data in twelve locations covering the various climatic belts of Nigeria were carried out. Nigeria rainfall has a usual zonal pattern and the vast majority of precipitation falls within a well-defined period. The coastal stations received more rainfall than the inland locations. The northern locations received less rainfall than southern locations. The onset period for the northern stations is May/June while the cessation period is September/October. The southern stations have April as their onset month while October is their cessation month. The southern stations have two peaks of rainfall in June/July and September. A period when rainfall ceases within the wet season exists in the south, and is referred to as ‘August break’. The northern stations have only one peak, which is in August. Annual trend of precipitation is positive in most of the southern stations while it is negative in most northern stations. At the ninety-nine percent confidence limits, all the stations have mean annual rainfall close to or within the limits except during El Nino Southern Oscillation (ENSO) years. Harmonic analysis reveals 3 to 4 and 7-8 years inter-annual cycle of precipitation which correspond to the warm and cold ENSO cycle. Temperature has a bimodal variation through the twelve months in a year. The two maxima occur in March/April/May and October/November while the minimum is in July/August. Annual temperature trend is positive (small slope) in some stations while it is negative in some not necessarily depending on the position. 1 results 1
- Ghana 1 results 1
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