Amimul Ahsan

A study on selection of probability distributions for at-site flood frequency analysis in Australia

The most direct method of design flood estimation is at-site flood frequency analysis, which relies on a relatively long period of recorded streamflow data at a given site. Selection of an appropriate probability distribution and associated parameter estimation procedure is of prime importance in at-site flood frequency analysis. The choice of the probability distribution for a given application is generally made arbitrarily as there is no sound physical basis to justify the selection. In this study, an attempt is made to investigate the suitability of as many as fifteen different probability distributions and three parameter estimation methods based on a large Australian annual maximum flood data set. A total of four goodness-of-fit tests are adopted, i.e., the Akaike information criterion, the Bayesian information criterion, Anderson–Darling test, and Kolmogorov–Smirnov test, to identify the best-fit probability distributions. Furthermore, the L-moments ratio diagram is used to make a visual assessment of the alternative distributions. It has been found that a single distribution cannot be specified as the best-fit distribution for all the Australian states as it was recommended in the Australian rainfall and runoff 1987. The log-Pearson 3, generalized extreme value, and generalized Pareto distributions have been identified as the top three best-fit distributions. It is thus recommended that these three distributions should be compared as a minimum in practical applications when making the final selection of the best-fit probability distribution in a given application in Australia.

Experimental Study on Various Solar Still Designs

Humankind has depended for ages on underground water reservoirs for its fresh water needs. But these sources do not always prove to be useful due to the presence of excessive salinity in the water. In this paper, the fabrication of seven solar still designs such as spherical solar still, pyramid solar still, hemispherical solar still, double basin glass solar still, concentrator coupled single slope solar still, tubular solar still and tubular solar still coupled with pyramid solar still and their performance evaluation in converting brackish water into fresh water for drinking are presented. The experiment was constructed and tested during January to May 2011. All the solar stills were operated in the same climatic conditions to analyze the influence of the modifications on the productivity. From the observations, the compound parabolic concentrator-assisted tubular solar still shows the maximum yield.

Life cycle cost analysis of a sustainable solar water distillation technique

This paper presents a detailed estimation of the fabrication cost, water production cost (WC), and cost payback period (CPP) using annualized life cycle costing for a tubular solar still (TSS). The operation and maintenance cost (OM) and the number of sunny days in a year (d) have a significant effect on the WC. The WC is raised from 3.1 to 4.4¥/L, if the OM increases from 5 to 18% of the capital cost, respectively. The WC is dropped by 35% (in average) when the d increases from 230 to 350 days. In addition, the CPP is greatly affected by the water selling prices and d. The CPP is dropped from 68 to 45 days due to the increase of d from 230 to 350 days (in average), respectively. The fabrication cost of the TSS (

Assessment of Municipal Solid Waste Management System in a Developing Country

5) and the WC (

MHD Mixed Convection in a Channel with a Triangular Cavity

31/m3) are affordable and much lower than the single-sloped passive solar still. Finally, it is revealed that the solar radiation is the most influential parameter on the productivity of TSS and a linear proportional relationship is found between them.

The development and applications of solar pond: a review

This study represents a few basic steps of municipal solid waste management practiced in the six major cities of Bangladesh, namely, Dhaka, Chittagong, Khulna, Rajshahi, Barisal, and Sylhet. A six-month field study was conducted to identify the solid wastes management steps such as storage at source, separation, on-site storage, collection, transportation, treatment, reuse, recycling, and ultimate disposal. This study addresses the role of the city authority to meet the demand of the city dwellers in solving this emerging socioenvironmental issue and the initiatives taken by some nongovernmental organizations and community based organizations. The problems and constraints of the solid wastes management system are also identified to find a sustainable management concept for the urban areas of Bangladesh.

Experimental Study on a Compound Parabolic Concentrator Tubular Solar Still Tied with Pyramid Solar Still

A numerical study has been carried out in an open channel, which have a heated triangular cavity at the bottom wall. The remaining walls of the channel are adiabatic. Flow inlets to the channel with uniform velocity and fully developed flow are accepted at the exit of the channel. Steady state mixed convection by laminar flow has been studied by numerically solving governing equations to obtain flow field and temperature distribution under the magnetic field and Joule effect. Equations are solved via the Galerkin weighted residual finite element technique. Calculations are performed for different governing parameters such as Hartmann number (10 ≤ Ha ≤ 100), Reynolds number (100 ≤ Re ≤ 2,000), Rayleigh number (103 ≤Ra ≤ 105), Joule parameter (0 ≤ J ≤ 5), and Prandtl number (1 ≤ Pr ≤ 10). It is found that heat transfer decreases with an increasing of the Hartmann number especially at higher values of Rayleigh number. Fluid temperature at the exit of the channel also decreases with increasing of Hartmann number. Fluid temperature at the outlet of the channel becomes higher at low Reynolds number and higher Rayleigh number. However, it decreases with the decreasing of the Reynolds number.

Evaporativity and Productivity of a New Tubular Solar Still

Solar energy is a substantial source of clean and renewable energy. Recently, solar pond technology has made a great progress due to the fact that solar ponds can collect and store heat in the same time which has reduced the cost significantly thus making it an area of interest for the industry and researchers. Several salt gradient solar ponds have been constructed in many regions around the world. This paper reviews the various schemes of solar ponds, in addition to their performance, optimization, heat extraction mode and applications as reported in the literature. The maintenance and cost effect on solar pond have also been discussed.

Characterization of Rice Husk Carbon Produced through Simple Technology

Water is a nature’s gift and it plays a key role in the development of an economy and in turn for the welfare of a nation. Non-availability of drinking water is one of the major problem faced by both the under developed and developing countries all over the world. Around 97% of the water in the world is in the ocean, approximately 2% of the water in the world is at present stored as ice in polar region, and 1% is fresh water available for the need of the plants, animals and human life [1]. Researchers have been carried out in this method by Nij‐ meh, et al., [2], they have been investigated the regenerative, conventional and double-glasscover cooling solar still theoretically and experimentally. Several system parameters were also investigated with respect to their effect on the productivity, namely, water with and without dye in the lower basin, basin heat loss coefficient, and mass of water in the basins and mass flow rate into the double-glass cover. Thermal performances of a solar still cou‐ pled with flat plate heater along with an evaporator-condenser have been analyzed by Rene Tchinda, et al., [3]. They reported that the theoretical solar still productivity is in reasonably good agreement with the experimental distillation yields. Thermal performances of a regen‐ erative active solar distillation system working under the thermosyphon mode of operation have been studied by Singh and Tiwari for Indian climatic condition. It is concluded that (i) there is a significant improvement in overall performance due to water flow over the glass cover and (ii) the hot water available due to the regenerative effect does not enhance the out‐ put. They derived expressions for water and glass temperatures, hourly yield and instanta‐ neous efficiency for both passive and active solar distillation systems [4]. Chouchi et al., [5] have designed and built a small solar desalination unit equipped with a parabolic concentra‐ tor. The results show that, the maximum efficiency corresponds to the maximum solar light‐

Housing Problems for Middle and Low Income People in Bangladesh Challenges of Dhaka Megacity

A Tubular Solar Still (TSS) has being developed by our research group and a transparent vinyl chloride sheet of 0.5mm in thickness was used for the tubular cover of the first model designed by Islam KMS (2007). Since then we have been improving the first model from the viewpoint of assembly, economy and maintenance. A polythene film of 70µm in thickness was, therefore, adopted as the cover of the second model. As a result, the cover weight of the second model was one twelfth lighter than that of the first model. An experiment was carried out to investigate the evaporation and production performance of the second model and the thermal properties of the tubular cover, humid air and water in a trough inside the still. It was revealed that the hourly evaporation and production fluxes became a little lower for the second model than the first one under the same conditions of ambient air temperature and relative humidity and radiant heat flux. One of the reasons would be the difference in the water depth between the two experiments. Another possible reason of reducing the productivity would be the stagnant of the condensed water due to the undulations of the polythene film.