Investigation into the pressure-driven extension of the EPANET hydraulic simulation model for water distribution systems

Several hydraulic modelling approaches have been proposed previously to simulate pressure deficient operating conditions in water distribution networks more realistically. EPANET-PDX is an extension of EPANET 2 that has an embedded logistic nodal head-flow function. The EPANET-PDX algorithm was investigated to address the weaknesses uncovered under conditions of extremely low pressure. It was observed that, under certain circumstances, the norm of the system of equations increased from one iteration to the next. A criterion that detects false convergence was included. In general, in the examples considered, the formulation proposed had more consistent computational properties, required fewer iterations of the global gradient algorithm, and application of the line minimization procedure was frequent. The formulation proposed is significantly faster in conditions of extremely low pressure. The hydraulic and water quality modelling functionality of EPANET 2 was preserved. For the operating conditions with satisfactory pressure, where direct comparisons with EPANET 2 were possible, EPANET 2 was consistently faster

Effects of pre- and post harvest treatments on changes in sugar content of tomato

The present investigation was aimed at evaluating the combined effect of pre- and post harvest disinfection and evaporatively coolled storage on the changes in sugar content of tomato (Lycopersicon esculentum Mill). The preharvest treatments used were ComCat®, manure, NP and the combinations of ComCat® with the two forms of fertilizers and a control. The tomatoes were periodically analyzed for reducing sugar and total sugar. Preharvest ComCat® and ComCat® + manuretreatments improved the quality of tomato in terms of maintaining higher (P < 0.05) leveles of sugar during storage. Storage at ambient conditions resulted in rapid change in sugar that resulted in qualitydeterioration of tomatoes. Disinfection seemed to have very limited effect on the changes in sugar content of tomatoes during storage. Two-way interactions between preharvest and storage conditionson changes in total sugar were significant at P < 0.05 level during the first week of storage and at

The influence of the combined microwave power and hot air ventilation on the drying kinetics and colour quality of tomato slices

Tomato is one of the most important fruit used as an ingredient in different foods in food processing and preparation. Fresh tomato consists of about 91% of moisture. Tomato has to pass through all three rates of drying (constant, first and second falling rate period) during drying, using hot air ventilation, and requires prolonged time with much of quality changes. In this study, microwave assisted hot air ventilation drying of tomato slices had been considered. Microwave oven working at 2450 MHz, using different power densities (1, 2 and 3 W g-1) was combined with hot air ventilation at 50°C and hot air ventilation drying without microwave power at 40, 50, 70 and 80°C to dry tomato slices down to 10% moisture content. The drying characteristic curve was analyzed to determine the drying time. The tomato slice sample dried faster when subjected to microwave heating, coupled with hot air ventilation at 50°C. The drying times required for tomato slices to reach 10% moisture content were found to be 3.2, 2.5 and 1.3 h, using 1, 2 and 3 W g-1 microwave power densities, coupled with 50°C hot air ventilation, respectively. On the other hand, the drying time of tomato slices to 10% moisture content required 20.5, 13.1, 9.6, 6.8 h for drying at 40, 50, 70 and 80°C, using hot air ventilation without supplementing heating with microwave power. Microwave drying maintained the superior colour of tomato slices after drying period, compared to the other treatments.Key words: Microwave, tomato slice, drying equation, colour, drying rate, moisture content

Water Supply and Health: Drinking water and Sanitation Coverage in Ethiopia 1990 - 2015 Review

Background: Human health, incorporating physical, social and psychological well-being, depends on an adequate supply of potable water and a safe environment sections. Waterborne infections are one of the commonest problems in developing countries. Access to safe drinking water and basic sanitation needs will eliminate vast part of water-borne disease cases. Objectives: to assess the trends safe water coverage and sanitary conditions in Ethiopia together with the challenges of the sector. Methods: In depth literature survey from online published peer reviewed articles, publications from International organization and Ethiopia ministry of health was used to assess the trend and access of improved water and sanitation coverage since 1990 to 2015 in Ethiopia. Results: Among 93 articles, 45 of them have important information and included in the quantitative review. To this end Ethiopia has reached the Millennium Development goal of access to safe water and the national coverage reached to 68.5% and 33% for sanitation facilities. Ethiopia is not on the right track to reach for sanitation target (47%) of 2015. The development trend for water coverage and sanitation facilities shows that urban dwellers (16% of the population) are more benefited than the rural (84%) citizens. Poor access of sanitation and improved drinking water in rural part is resulted due to improper planning, malfunction water scheme utilities, and other factors. Conclusions: Despite, the efforts made to increase the access to safe drinking water and sanitation facilities to the population in the last 15 years; water related diseases are still one of the top ten diseases in the country. Protecting the source alone is not sufficient enough to reduce waterborne diseases unless point of use treatments and hygienic handling of water is practiced. Additional commitments and efforts are required post 2015 to assure the sustainability, access to the basic human right, water

Integration of hydraulic and water quality modelling in distribution networks : EPANET-PMX

Simulation models for water distribution networks are used routinely for many purposes. Some examples are planning, design, monitoring and control. However, under conditions of low pressure, the conventional models that employ demand-driven analysis often provide misleading results. On the other hand, almost all the models that employ pressure-driven analysis do not perform dynamic and/or water quality simulations seamlessly. Typically, they exclude key elements such as pumps, control devices and tanks. EPANET-PDX is a pressure-driven extension of the EPANET 2 simulation model that preserved the capabilities of EPANET 2 including water quality modelling. However, it cannot simulate multiple chemical substances at once. The single-species approach to water quality modelling is inefficient and somewhat unrealistic. The reason is that different chemical substances may co-exist in water distribution networks. This article proposes a fully integrated network analysis model (EPANET-PMX) (pressure-dependent multi-species extension) that addresses these weaknesses. The model performs both steady state and dynamic simulations. It is applicable to any network with various combinations of chemical reactions and reaction kinetics. Examples that demonstrate its effectiveness are included

Multiobjective evolutionary optimization of water distribution systems : exploiting diversity with infeasible solutions

This article investigates the computational efficiency of constraint handling in multi-objective evolutionary optimization algorithms for water distribution systems. The methodology investigated here encourages the co-existence and simultaneous development including crossbreeding of subpopulations of cost-effective feasible and infeasible solutions based on Pareto dominance. This yields a boundary search approach that also promotes diversity in the gene pool throughout the progress of the optimization by exploiting the full spectrum of non-dominated infeasible solutions. The relative effectiveness of small and moderate population sizes with respect to the number of decision variables is investigated also. The results reveal the optimization algorithm to be efficient, stable and robust. It found optimal and near-optimal solutions reliably and efficiently. The real-world system based optimisation problem involved multiple variable head supply nodes, 29 fire-fighting flows, extended period simulation and multiple demand categories including water loss. The least cost solutions found satisfied the flow and pressure requirements consistently. The cheapest feasible solutions achieved represent savings of 48.1% and 48.2%, for populations of 200 and 1000, respectively, and the population of 1000 achieved slightly better results overall

Practical Application Of Pressure-Dependent EPANET Extension

Hydraulic models have been widely used in the design and operation of water distribution system (WDSs). The models enable planning for possible changes in the system under a wide range of conditions. Under abnormal operating condition, for instance, WDSs become pressure deficient and unable to satisfy demand fully. In such circumstances, pressure dependent models are suitable to quantify the shortfall in flow and pressure accurately for crucial decision-making. Most recently, a pressure dependent extension of the renowned EPANET hydraulic simulator was developed to enable modelling of pressure deficient networks. The model has an integrated pressure dependent demand (i.e. nodal flow) function coupled with a line search and backtracking procedure to facilitate convergence. Extensive verifications were conducted on the model using benchmark and real life networks and good modelling performances were accomplished. The model was combined with multi-objective genetic algorithm for optimisation of design, rehabilitation and operation of WDSs. It generated superior results for benchmark as well as real life networks in terms of cost, hydraulic performance and computational time in reference to previous solutions. It has also been utilised for water quality modelling of real life networks. Overall, the model has not experienced convergence problems when executing the various simulations. Having demonstrated the robustness and benefits of the model previously including seamless integration in genetic algorithms, it would be greatly beneficial on investigating ways of improving the algorithm further. In this work, the line search and backtracking procedure of the algorithm has been improved. This has improved the robustness further by enhancing greatly the computational properties for low flow conditions and increasing the algorithm’s consistency over a wider range of operating conditions. Extended period simulations were executed on real life network considering source head variations and pipe closure conditions

Effects of disinfection, packaging and evaporatively cooled storage on sugar content of mango

The present investigation was undertaken to evaluate the effect of post-harvest disinfection, packaging, evaporative cooling storage and their combined effect on the changes in sugar content ofmango (Mangifera indica L.). The experiment was laid out in a factorial combination of disinfection, packaging and storage in a randomized complete block design with three replications. The mangoeswere periodically analyzed for reducing sugar and total sugar. Non-reducing sugar was computed from the difference between experimental reducing and total sugars. Storage conditions significantly (P 0.01) affected sugar content in mangoes. Storage at ambient conditions with higher temperature and lower relative humidity as compared to the evaporatively cooled storage resulted in rapid deterioration in sugar content of the mangoes. During the storage period, packaging generally maintained higher (P 0.01) levels of reducing sugar, non-reducing sugar and total sugar. Similarly, disinfection treatment significantly (P 0.01) affected the changes in reducing, non-reducing and total sugars of mangoes during storage. Two-way interactions were significant (P 0.01) in terms of the changes in sugar content of mangoes. The benefits of the combined effect of post-harvest treatments on mangoes included maintenance of high reducing sugar, non-reducing sugar and total sugar

Effect of combined application of organic-P and inorganic-N fertilizers on yield of carrot

A study was undertaken to assess the effect of combined application of organic-P and inorganic-N fertilizers on yield and yield components of carrot (Daucus carota L.). The field experiment was conducted at Kombolcha ATVET College, South Wollo, Ethiopia. Seeds of carrot were sown on raised beds of a black clay soil. “Orga “and urea were used as sources of phosphorus and nitrogen, respectively, for the fertilizer treatments. The rates of fertilizers used in the experiment were, 309 kg“orga” ha-1 combined with six rates of urea (0, 68.5, 267.2, 274,342.5 and 411 kg urea ha-1). The field experiment was laid out in a randomized complete block design with seven fertilizer treatments,replicated five times. Yield and yield components of carrot were significantly influenced by the preharvest combined application of “orga” and urea treatments. Pre-harvest application of 309 kg “orga”ha-1 combined with 274 kg urea ha-1 increased yield of carrot by 46% compared to the control treatment. The values of yield components of carrot were also increased in response to the increased rate ofcombined “orga” and urea fertilizer application. The result showed that the combined application of 309 kg ha-1 “orga”and 274 kg ha-1 urea resulted in the maximum yield of carrot

Effects of preharvest treatments on yield and chemical composition of tomato

Postharvest losses in tomato (Lycopersicon esculentum L.) are among others, the prime factor affecting the quantity and quality of tomato fruits in the market. Options to avert these losses are limited, and thus the need to design research studies that are geared to developing such strategies. A field experiment was therefore conducted to study effects of preharvest treatment of ComCat® spray, manure, NP fertilisation and the combinations of ComCat® with the two forms of fertilisation and the control on yield and quality of tomato in semiarid climate in eastern part of Ethiopia. The experiment was conducted using randomised complete block design with 3 replications. Data were collected from two centeral rows of treatment plots to assess vegetative growth, yield and the chemical composition of fruits at harvest. The result showed that the use of ComCat® and its combination with manure gave the highest total yield 58.53 tha-1 and 55.77tha-1 of which 94% and 93% weremarketable and total yield, respectively. By using manure and NP fertiliser it was observed that both marketable and total yield was not significantly influenced. The control tomato plants were found to give higher total and marketable yield on comparison with the preharvest ComCat® + NP treatment. The chemical qualities of tomatoes were improved by preharvest ComCat®, ComCat® + manure and ComCat® = NP treatments. Based on the varied performance of the treatements imposed, adoption of a particular teatment will depend on a specificrecommendation dormain