Numerical investigation of homogeneous expansion and lateral solid mixing in gas-fluidized beds.

This research project is concerned with the numerical investigation of the behaviour of homogeneous and bubbling gas-fluidized beds. We started by investigating the homogeneous expansion of gas-fluidized beds using the Richardson & Zaki (1954) equation. We modelled the stable expansion of gas-fluidized beds of different diameter, accounting for enduring contacts among particles and wall effects. We solved the model numerically to obtain the bed expansion profiles, back-calculating from them the values of the expansion parameter n. To validate our model, we carried out fluidization and defluidization experiments, analyzing the results by means of the Richardson & Zaki equation. We obtained a reasonable agreement between numerical and experimental findings; this suggests that enduring contacts among particles, which are manifestations of cohesiveness, affect homogeneous bed expansion. The results showed that homogeneous gas-fluidized beds do not consist of particles floating freely; rather they are made up of particles in sustained frictional contacts. We then investigated the process of lateral solid mixing in bubbling fluidized beds, adopting the Eulerian-Eulerian modeling approach. To quantify the rate at which solids mix laterally, we used a lateral dispersion coefficient (Dsr). The values of Dsr obtained numerically are larger than the experimental ones, within the same order of magnitude. The overestimation has a twofold explanation. On one side, it reflects the different dimensionality of simulations (2D) as compared with real fluidized beds (3D), which affects the degrees of freedom of particle lateral motion. On the other, it relates to the way frictional solid stress was modelled. To investigate how sensitive the numerical results are on the constitutive model adopted for the frictional stress, we ran the simulations again using different frictional models and changing the solid volume fraction at which the bed is assumed to enter the frictional flow regime (Φmin). We observed that Dsr is quite sensitive to the latter. The results show that accurate prediction of lateral solid dispersion depends on adequate understanding of the frictional flow regime, and accurate modelling of the frictional stress which characterizes it. We further examined the influence of simulation dimensionality in numerical results. We ran 3D CFD simulations using the same powder, the same operational conditions and the same computational setup as in the previous 2D simulations. The 3D simulations predicted Dsr more accurately than the 2D simulations, the simulation dimensionality appearing to be an important factor. To analyse further the role of frictional stress models, we ran 3D DEM simulations. The simulation results agreed reasonably well with the empirical data, but their accuracy depended on the values used for the collision parameters; also, the 3D CFD simulations matched the empirical data more closely. Altogether, we thus concluded that the simulation dimensionality plays a dominant role in predicting Dsr accurately

Childhood immunization perception and uptake among mothers of under-five children attending immunization clinics in Osogbo, South Western, Nigeria

Objective: Immunization is one of the most cost-effective public health intervention as it saves millions of lives annually from vaccine preventable deaths. About 20 per cent of under- five children; die from a vaccine-preventable disease annually hence, the need to determine the perception and the factors militating against the uptake of immunization among mothers of under-five children. The study aimed at determining the perception and uptake of childhood immunization among mothers of under-five children attending post-natal Clinics in Osogbo, South Western, Nigeria.Methods: The study was a descriptive cross-sectional study with a sample size of 320 mothers selected using a systematic sampling technique. Data was collected using a pre-tested semi-structured interviewer administered questionnaire. SPSS Version 17 was used for analysis.The level of statistical significance was set at P-values < 0.05, at the confidence interval of 95%.Results: A significant proportion of the respondents (43.8%) were within the ages 21-30 years and 76.3% of the mothers were educated up to tertiary level. Majority of the respondents, 98.8% had good perception of immunization. About 85.7% of the children were fully immunized according to national immunization schedule. However long waiting time and inability to leave the workplace have a negative effect on uptake of immunization as 41.1 % and 31.9% of the respondents attributed the reason for missing immunization clinic days to these two factors respectively.Conclusion: Reduction of the amount of time spent in the immunization clinic and enactment of enabling policy to ensure nursing mothers are permitted to take their children for immunization during working hours would go a long way to improve rate of immunization uptake of children.Keywords: Perception,Uptake, Under-five, Postnatal clinic and Immunization

Market Opportunities and Profitability of Tree Crop Planting in Nigeria

Investing in trees offer financial and social returns for years to come and it is a lucrative long-term investment in Nigeria. Despite the substantial gain on investment in tree planting, only few people are still involved in the business. This paper analyzed the profitability of investment in tree crop planting for income generation. Benefit Cost Ratio (BCR) and Net Present Value (NPV) were calculated to determine the financial viability of tree crop planting. The study showed that tree crop planting is a profitable business as shown by positive NPV of ₦2,187,822.0 and N2, 782,214.97 for Tectonia grandis and Moringa oleifera plantations respectively, after 10-years of maturation and harvesting at 14 % discount rate with a B/C Ratio of 1.97 and 1.6 respectively. Also, NPV of N1, 575,487.10 for a 5-year small scale private nursery establishment with a B/C Ratio of 2.79 at a 14% discount rate also confirm that the investment on nursery establishment is highly profitable. It is recommended that with adequate support and incentives, farmers can take advantage of these opportunities and invest in nursery enterprise and tree crop sub-sector of the economy Keywords: Market opportunities, Tree planting, BCR, NP

EVALUATION OF THE QUALITY CHARACTERISTICS OF COCOA BEAN DRIED USING DIFFERENT DRYING TECHNIQUES

Processing techniques, particularly drying because cocoa beans are extremely sensitive to moisture, have a significant impact on the quality of the final product. Fermented cocoa beans were dried using the NSPRI parabolic solar tent dryer (PSTD), wooden solar dryer (WSD), and open-air drying (OAD). The dried cocoa beans’ respective moisture contents (MCs) for PSTD, WSD, and OAD were 5.94%, 6.01%, and 6.82%, respectively. The corresponding MCs for the dried cocoa beans from PSTD, WSD, and OAD were 5.94%, 6.01%, and 6.82, respectively. It was found that the cut test scores for PSTD, WSD, and OAD were 1000, 985, and 965, respectively. This showed that, in contrast to those from WSD and OAD, the dried cocoa beans obtained from PSTD were fully brown. For WSD, OAD, and PSTD, respectively, the obtained pH values were 5.60, 5.65, and 5.80, and the total titratable acidity was 11.70 meq NaOH 100–1 g, 14.10 meq NaOH 100–1 g, and 18.30 meq NaOH 100–1 g for PSTD, WSD, and OAD, respectively. Food products’ shelf life may be indicated by the titratable acidity value. Due to its enclosed design, the NSPRI PSTD has an advantage over other drying methods because it completely eliminates the possibility of external and microbial contamination of the cocoa beans

Management of inputs resources in small-scale catfish farming in Oyo State, Nigeria

This study examined management of pre-stocking, stocking and harvest activities of small-scale catfish farmers in Oyo State, Nigeria. Structured questionnaires were used to collect the needed information and descriptive statistics was use to analyze the collected data. The results show that earthen and concrete pond are the two major ponds utilized by catfish farmers. The cost of pond construction varied with size, location, soil type and the cost of materials; so most farmers rented their ponds. The dimension of earthen pond varies between 53.51m2 and 891.87m2 with a mean of 197.34±2.48m2. The dimension of concrete pond varied between 13.94m2 and 83.61m2, with a mean of 45.89 ± 8.04m2. Many (41.5%) catfish farmers financed their business with their personal savings. Most fish farms are located close to streams for steady supply of water. Most (68.5%) farmers stocked juvenile while 31.5% stocked fingerlings. Farmers fed their fish with respect to their weight, satiation or availability of feed; but majority fed twice per day. Most farmers harvest catfish twice per year. Farmers should therefore know that proper and efficient management of input variables are prerequisite for profitability in catfish production. Keywords: Earthen pond; juvenile; fingerlings; feed; Water; Profitabilit

Market Opportunities and Profitability of Tree Crop Planting in Nigeria

Investing in trees offer financial and social returns for years to come and it is a lucrative long-term investment in Nigeria. Despite the substantial gain on investment in tree planting, only few people are still involved in the business. This paper analyzed the profitability of investment in tree crop planting for income generation. Benefit Cost Ratio (BCR) and Net Present Value (NPV) were calculated to determine the financial viability of tree crop planting. The study showed that tree crop planting is a profitable business as shown by positive NPV of \u20a62,187,822.0 and \u20a62,782,214.97 for Tectonia grandis and Moringa oleifera plantations respectively, after 10-years of maturation and harvesting at 14 % discount rate with a B/C Ratio of 1.97 and 1.6 respectively. Also, NPV of \u20a61, 575,487.10 for a 5-year small scale private nursery establishment with a B/C Ratio of 2.79 at a 14% discount rate also confirm that the investment on nursery establishment is highly profitable. It is recommended that with adequate support and incentives, farmers can take advantage of these opportunities and invest in nursery enterprise and tree crop sub-sector of the economy

Economic, nutritional and medicinal values of African walnut (Tetracarpidium conophorum) in Nigeria (Hutch. & Dalziel): a review

The Nigeria Walnut (Tetracarpidium conophorum) is a climber crop species that help in poverty reduction through improvement of the purchasing power of families and their standard of living. African walnut has proven evidence that leads to general acceptability to its protective effects against certain diseases majorly the cardiovascular disease (CDV). It has many other medicinal values such as treatment of Diabetic, maintenance of healthy bone, Anti-malarial, diseases prevention, pregnancy protection and sperm improvement, weight management and so on. The consumption of this fruit is not only effective for the health of man but contributes to other lifestyles characteristics backed up by evidence from certain scientific investigations. However, the challenges facing its year round availability have not been fully documented and data related to its contributions to livelihoods of rural farmers and it nutritional value is not readily available to the populace, thereby places the plant in danger of genetic extinction and disappearance which have the potential to restrict its development options. Therefore, this paper reviewed the monetary contribution of African Walnut, its potential roles in poverty reduction, commitment to national advancement and value added exports from Nigeria, hence the investigation is expected to bridge some of this gap, giving an overview of the present information encompassing the economic commitment of Walnut, it nutritional and medicinal values in Nigeria. Key words: Economics, Nutrition, Medicinal Benefits, Chemical composition, Walnu

Determinant of Agroforestry Practices among Small Holder Farmers in Oyo State Nigeria

The multiplicity of agroforestry practices demand the choice of appropriate methods that will give the rural farmers an excellent result. Thus, this study analysed the factors determining the choice of agroforestry practices among small holder farmers in Oyo State, Nigeria. Primary data was obtained using multi-stage sampling technique. Structured questionnaire was administered to 250 selected small holder farmers to elicit relevant information and 211 was retrieved and used for this study. The findings revealed that most 55% of the farmers chose agrisilvicutural system while 33.2% and 11.8% of the farmers chose agrosilvopastoral and silvopastoral systems respectively. Most of the farmers were males 89.1%, with average age of 47years indicating they were relatively young with basic formal education. The average farm size of 3.34ha indicated that the study covered small holder farmers. The multinomial logit result showed that factors such as educational level, meeting attendance, type of labour used, household assets significantly determined the choice of agroforestry practices adopted by the farmers. The study therefore recommends the implementation of policies that promote more enlightenment on the benefits of agroforestry to both the educated and non-educated farmers to facilitate quick adoption, provision of incentives to farmers that attend meetings regularly and making available improved agroforestry methods and practices to enhance wider suitability of agroforestry practices

Assessment of Extension Officers Contribution to Cocoa Production in Nigeria

This study was carried out to evaluate the extension officer contribution to cocoa production in Nigeria. Multistage sampling technique was used, where two hundred and sixteen questionnaires were distributed in Osun and Ondo state , the information gathered were analyzed using descriptive statistic such as; frequency and percentage, while chi-square analysis was used to analyze the data obtained. From the results, married (77.6%), male (84.0%), secondary school holders (52.0%), between 40-49 (34.4%) years old farmers were seen as the highest cocoa producers. Extension training(64.0%), commercial agents(64.0%), fellowship(52.8%), self observation(76.0%) were the best source of information on extension service of cocoa farming , most respondents (65.0%); get extension training programme at regular basis, identified Constraints facing cocoa production in the study area includes deficient credit facilities, high cost of labour, bad road, poor marketing/storage facilities, lack of technical knowledge / assess to technical tools and so on. in view of afore mentioned result it is therefore recommended that the government should make loan available to the cocoa famers at very low interest rate and urge cocoa farmers to form cooperative society, strengthen their agricultural extension agents so that they will be able to rain cocoa farmers on the basic things they should know about primary processing such as fermentation and drying of cocoa beans in improving the quality in Nigeria to meet international market