Determination of the parameters for design of flexible plastic tank

The need to provide emergency water supplies in remote locations and to store water in small, irregular spaces was the main motivation for the research study. The flexible plastic tank provides a good solution to the challenges of efficient water supply to remote areas but has the disadvantage of creeping incessantly during use and does not recover its original dimensions after loading. This project sought to establish the limits within which the flexible HDPE tank may be used in hot tropical climates for water storage. The creep and recovery characteristics of the material were determined for the range of loads and temperatures at which the material is likely to be applied. A set of equations was developed from the creep and recovery curves to estimate the values of creep and recovery within the temperature range 30°C - 50°C and for stresses ranging from 0.781 to 1.563 MPa just by knowing only the applied stress and the operating temperature. Estimates were also provided for the expected permanent expansion of the material under load, when loaded once and when loaded and unloaded intermittently

Analysis of the weld strength of the High Density Polyethylene (HDPE) dam liner

An analysis was carried out to determine the strength of welded joints in High Density Polyethylene (HDPE) dam liners. Samples were collected of welded joints and subjected to tensile tests and creep test. It was observed that the welded joints from field welded samples were much weaker and had a very low straining capacity than the un-welded material. The field welded specimens registered average strengths of 5 MPa as compared to 12 MPa of un-welded specimens and a maximum strain at fracture of 0.5 as compared to 3.5 of un-welded specimens. As a result of the weak welds it was found necessary to conduct further research into the best welds possible and a protocol for hot air and hot knife welding was developed. It was shown that for hot air welding while holding the width of the weld, applied pressure and dwell time of the pressure constant at 2.6cm, 0.3 MPa and 60 s, the recommended temperature of the hot air to achieve the strongest weld was 176 and for hot knife welding the recommended temperature of the knife was 400°C

Drying characteristics and energy requirement of drying cowpea leaves and jute mallow vegetables

Thin layer drying of cowpea leaves (Vigna unguiculata) and jute mallow (Corchurus olitorious L) (African leafy vegetables) was studied at different temperatures (40oC -100oC) in a convective laboratory dryer. The study determined the drying characteristics of the vegetables, the maximum drying temperature and the drying energy requirements. Moisture content of the African leafy vegetables was determined on dry basis and the data were used to calculate moisture ratios and drying curves were plotted. The drying occurred in the falling rate period. The experimental data were fitted to fourteen thin layer drying models and the most appropriate drying model determined using correlation coefficient, mean square error and standard error of estimate. The model developed by Page showed good agreement with the data obtained from the experiments of this study because it consistently returned the required attributes from statistical analysis and its simplicity. The energy requirement of drying vegetables at the different temperatures was calculated. Cowpea leaves had a longer drying time of 304 min and a higher specific energy requirement of between 168 J/g at 100oC and 11.2 J/g at 40oC while jute mallow had a drying time of 256 min and an energy requirement of 155.3 J/g at 100oC and 10.6 J/g at 40oC respectively. <w:LsdException Locked="false" P

Modeling drying of seed maize using super absorbent hydrogel under hermetic conditions

The objective of this study was to establish the feasibility of applying the Page, Two term exponential, Newton, Logarithmic and Henderson and Pabis mathematical drying models for predicting the drying kinetics of seed maize using super absorbent hydrogel under hermetic conditions. To achieve this, the study was conducted using hydrogel to seed maize ratios by weight of 0:1, 1:5, 1:10 and 1:15 at four different drying temperature levels of 25oC, 30oC, 35oC and 40oC at different initial seed maize moisture contents of 16%, 28% and 53% (dry basis). The moisture data obtained were fitted into the five drying models using non-linear regression analysis (MS Excel 2003TM) based on the minimization of sum of squares by adjusting the model constants. The coefficient of determination (R2), root mean square error (RMSE) and chi-square (X2) were criteria for selecting the best model. High values of coefficient of determination (R2 > 0.95) were obtained for all the five drying models while the corresponding values of X2 and RMSE were in the range of (0.0016-0.0141) and (0.0400-0.3045) respectively. As a result Logarithmic model was the best fitted model with R2 (0.9749-0.9876) and the weakest values of X2 (0.0016-0.0036) and RMSE (0.04-0.128)

Characterization of brewery waste water and evaluation of its potential for biogas production

The issue of global warming and climate change is strongly receiving public attention and has become a major environmental concern both nationally and internationally. Brewing industries are among the largest consumers of water and the largest source of organic effluent mostly from the brewing, cleaning, and cooling processes which must be treated to allowable levels to reduce environmental pollution. Close to 10 L water is used for every 1 L beer that is brewed, though the amount of water in the final beer is small. A study was undertaken to characterize and assess the variations in the quality of untreated brewery waste water. Samples from different process streams including brewing line, clean in place line and mixing line from two brewing industries in Kenya were analyzed for BOD5, COD, TDS, TSS, sodium, total nitrogen and phosphorous using standard method as per American Public Health Association (APHA). There was a significant variation (p<0.001) in the all the physicochemical parameters between the industries and a significant interaction (p<0.001) between sampling point and the company. Analysis of the BOD to COD ratio showed the biodegradability index to range from 0.039 to 0.567 for brewing line, 0.177 to 0.766 for cleaning in place and 0.776 to 0.911 for mixing point, thus the waste water was found to be easily biodegradable at the mixing point for all the industries. However pretreatment would be required to improve anaerobic digestion

Modélisation et simulation multi-agent de la propagation d'une épidémie de choléra: cas de la ville de Ngaoundéré

Dans ce travail nous avons utilisé le concept de la modélisation et de la simulation multi-agent pour développer un simulateur qui décrit la dynamique d'une épidémie de choléra. Nous l'avons développé dans la plate-forme multi-agent GAMA 1 en y intégrant le système d'information géographique de la ville de Ngaoundéré comme environnement des agents. Ensuite quelques simulations y ont été exécutées sur un ensemble de jeux de données relatif à la sensibilisation et l'assainissement. Les résultats obtenus à l'issu de ces simulations nous donne de suggérer une stratégie de contrôle optimal axées sur trois points essentiels portant sur l'identification rapide des infectés, la sensibilisation immédiate des populations et surtout de la basse classe et l'assainissement rapide des zones à risque. ABSTRACT. In this work we used the concept of multi-agent modelisation and simulation to conceive one multi-agent model who describe dynamic of cholera epidemic. we implement this model in the multi-agent plate-form GAMA by making use geographical information system of Ngaoundere town as environment. The results obtained suggest an optimal control strategy focused on three essential points relating to the rapid identification of the infected, the immediate awareness of the populations and especially poor people and the rapid sanitation of risk areas

Modélisation et simulation multi-agent de la propagation d'une épidémie de choléra: cas de la ville de Ngaoundéré

In this work we used the concept of multi-agent modelisation and simulation to conceive one multi-agent model who describe dynamic of cholera epidemic. we implement this model in the multi-agent plate-form GAMA by making use geographical information system of Ngaoundere town as environment. The results obtained suggest an optimal control strategy focused on three essential points relating to the rapid identification of the infected, the immediate awareness of the populations and especially poor people and the rapid sanitation of risk areas.Dans ce travail nous avons utilisé le concept de la modélisation et de la simulation multi-agent pour développer un simulateur qui décrit la dynamique d'une épidémie de choléra. Nous l'avons développé dans la plate-forme multi-agent GAMA 1 en y intégrant le système d'information géographique de la ville de Ngaoundéré comme environnement des agents. Ensuite quelques simulations y ont été exécutées sur un ensemble de jeux de données relatif à la sensibilisation et l'assainissement. Les résultats obtenus à l'issu de ces simulations nous donne de suggérer une stratégie de contrôle optimal axées sur trois points essentiels portant sur l'identification rapide des infectés, la sensibilisation immédiate des populations et surtout de la basse classe et l'assainissement rapide des zones à risque

Mechanized tillage-induced compaction and its effect on maize (Zea Mays L.) growth and yield—a comprehensive review and analysis

While agricultural engineers are concerned with physico-mechanical properties of arable soils, agronomists tackle crop management husbandry as soil scientists’ dwell on bio-chemical properties. Such diverse and isolated interests seldom report any interaction or integrated effect of biological, agronomical, and physico-mechanical parameters of soils affected by mechanized tillage induced compaction. This paper reviews intrinsic effects of mechanized tillage-induced compaction on soil-water-nutrient dynamics, crop growth, and yield of maize. Mechanized tillage induced top and subsoil compaction are caused by soil-tyre contact stresses and machinery axle loads respectively. Mechanized tillage-induced compaction reduced maize nutrient absorption levels of Nitrogen (N), Potassium (K), Magnesium (Mg), and Sodium (Na) by 13.5%, 51.4%, 50.4% and 51.5% respectively. Maize N uptake was least affected by tillage-induced compaction compared to P and K. Mechanized tillage-induced compaction improved maize root intensity, root mass and volume by over 50% in compacted topsoils but decreased by 90% in the sublayers. Maize root length, fresh and dry root mass, shoot elongation, height, and leaf area index reduced by 29%, 39.1, 37.8, 27.1, 10-21, and 67.8% respectively. In contrast, mechanized tillage-induced compaction improved soil-seed-soil-root contacts, soil-root-bonding root density and diameter, stiffness, anchorage, and root-lodging resistance of maize. Mechanized tillage induced compaction index and bulk density range of 1.5-3.0MPa and 1.2-1.52 Mg/m3 respectively are the critical levels beyond which maize rooting, growth and yield are impaired. Dependent on dynamic soil covariates, viz limiting water range, matrix suction potential and organic matter content; mechanized tillage-induced compaction reduces maize yield by as high as 50%

Quality Assessment of Rain and Storm Water Runoff for Nairobi City Industrial and Sub-Urban Areas

ABSTRACT Nairobi like most cities in the world is faced with water shortages because all the surface water sources have been tapped and the ground water overexploited, yet the water demand continues to rise as the population grows. The city must therefore seek alternative means of water supply. One of the promising sources is rainwater harvesting, which has successfully been adopted to supply water in many other cities. However, there is a concern about the quality of the rainwater falling through a heavily industrialized city atmosphere and flowing over polluted grounds. There is need to determine the quality of rainwater and the resulting storm water so as to make a decision on the best application or treatment of the water. The purpose of the study was therefore to determine the physical and chemical properties of rain and storm water runoff in sub-urban and industrial settings in Nairobi. Two sites were indentified namely Upper Kabete Campus (heavily vegetated agricultural suburb), and Jomo Kenyatta International Airport (heavily industrialized area of the city) to assess the water quality of rainwater received and storm water runoff exiting to drains. Water samples were collected directly from falling rain and also from runoff water at the sites for laboratory analysis. The samples were analyzed for water quality parameters namely pH, alkalinity, hardness, total dissolved solids, chlorides, calcium, nitrates, iron. The results from the two sites were compared statistically. It was found that the quality of rain water does not differ significantly in physiochemical parameters at 0.05 significant levels between the sub-urban and industrial setting. The falling rainwater was only slightly above the WHO requirements and required only modest treatment whole the storm water was significantly above the WHO limits and either need treatment or may be used for non potable application. Results of the study are useful in addressing challenges of water quality partly by encouraging use of rain and storm water for non portable uses and preserving the limited treated water for essential household uses

Effect of Soil tooling, Tractive wheeling, and Mechanical pulverization of Arable Soils in Tillage - A Systematic Review and Analysis

Abstract Seasonal soil-tool interactions, tractive wheeling and trailed tandem traverse of agricultural fields present ambiguities in defining and qualifying soil processing in tillage where the physio mechanical state of soil health is repeatedly perturbed. Precise and distinctive knowledge on quality characterization and mechanistic response behavior of soil-tool and soil-wheel interactions under tillage is sparse. We reviewed 116 state of art tillage studies in the US, Europe, UK, Australia, Africa, and Asia among others, concerning localized and integrated effects of soil-tool and soil-wheel interactions and associated dynamic response trends of mechanically distressed soils; to untangle and overcome persistent ambiguities in qualifying tilled soil state, expressed by physio-mechanical, biomechanical and hydromechanical soil heterogeneity. Studies revealed that soil-tool and soil-wheel interaction phenomena, and constitutive tractive tribologies portend sophisticated interrelations with dynamic, multivariate, and heterogeneous soil properties. Hitherto to such variabilities, soil-tool-wheel interactions and their perturbation descriptors have not consensually achieved any distinctive characterization under tillage. Nonetheless, tillage depth, tine widths, rake angles of attack, draft forces and traction performance had gained some generalized description of characterizing soil working. However, researchers still found it difficult to qualify the precise mechanistic relations of dynamic physio-mechanical soil states, unanimously and accurately with engaged tools in situ. This is by dint of, and amid multifaceted soil-tool-wheel-stress-strain interrelations that we consider dynamic and apart from soil type, are soil- tool and soil- wheel methodical. Attempts to fill this knowledge gap through soil tooling and soil wheeling models provided conditional results, defined and only due under the specified simulated model assumptions. We recommend further studies to elucidate and furnish with in-depth knowledge on dynamic soil response variabilities under complex tool-wheel stress loads, that are dynamically transmitted due to encounter with point specific and instantaneously varying properties of soil matrix in situ. This will optimize and accurately characterize soil-tooling, tractive wheeling, and trailed traverse in tillage. Key words. Tractor wheeling, Physio-Mechanical state, Penetration resistance, Soil tooling, draft force, Tractor-implement optimization