ARPN Journal of Engineering and Applied Sciences                         ISSN 1819-6608
 
 
 
ARPN Journal of Engineering and Applied Sciences                 August  2006  | Vol.1  No.2
Title: Comparison of strength performance of concrete with uncrushed or crushed coarse aggregates
Author (s):

Rifath Sharmin, Dr. Mushtaq Ahmed, Mohiuddin Ahmed and Forhat Afja Lubna

Abstract:

This study focuses on the relative performance of uncrushed aggregates and crushed aggregates for concrete in strength gaining. The study was conducted for medium grade concrete (concrete having cube compressive strength at 28 days between 6 Mpa to 50 Mpa). There is a general belief that crushed aggregates contribute higher strength in concreting compared to uncrushed aggregates. Contrary to this belief, our study revealed: uncrushed aggregates perform better than crushed aggregates in gaining strength for medium grade concrete. From the laboratory test of strength determination it was explored that uncrushed aggregate provide more strength (22% at 28 days) than crushed aggregates for medium grade concrete. Similar results were found for low grade concrete (cube strength at 28 days up to 15 Mpa) in a previous study relevant to mention: uncrushed aggregate is cheaper than crushed aggregate in the market of Bangladesh. Consequently, concrete with uncrushed aggregates will be cheaper. It can be concluded that uncrushed aggregates are appropriate for medium grade concrete for better performance in terms of strength and economy. Future study is required on high-grade (cube strength at 28 days between 51 Mpa to 100 Mpa) and super high grade concrete in similar line.

 
 
 
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Title:

Some exact solutions of equations of motion of a finitely conducting incompressible fluid of variable viscosity in the presence of a transverse magnetic field by transformation method

Author (s):

Muhammad Jamil and Najeeb Alam Khan

Abstract:

Using transformation method some exact solutions of equations of motion of a finitely conducting incompressible fluid of variable viscosity in the presence of a transverse magnetic field are determined. These solutions consist of flows for which the vorticity distribution is proportional to the stream function perturbed by a uniform stream. Streamline patterns for some of the solutions are also presented.

 
 
 
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Title: Investigation of Phosphate  and Ammonia-Nitrogen concentrations at some selected locations of the Malnichara channel and the Surma river
Author (s):

Rezaul Kabir Chowdhury and Sheikh Istiak Mohammad Ali

Abstract:

Sylhet city of Bangladesh is suffering from lack of structured sewerage and drainage system as well as from solid waste mismanagement. The Malnichara channel is responsible for surface runoff conveyance from its urban catchment to the receiving Surma River. In this study, an effort was made to investigate the status of concentrations of phosphate (PO4-3) and ammonia-nitrogen (NH3-N) at four locations viz. entrance point of Malnichara to the city, off taking point of Malnichara to Surma River, upstream and downstream point of Surma River to the off taking point. Data was collected from March-April and August–September 2005. Concentrations were measured using UV Spectrophotometer. The phosphate concentration was found to be within the permissible limits set by the Department of Environment (DoE) for fishing, irrigation and recreational purposes. However, ammonia-nitrogen was exceeding the limits.

 
 
 
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Title:

Hospital waste management in Sylhet city

Author (s):

Md. Shahjahan Kaisar Alam Sarkar, Muhammad Azizul Haque and Tanvir Ahmed Khan

Abstract:

Hospital waste has not been got proper attention in Sylhet City Corporation (SCC), which is also very common for other cities of Bangladesh. Even the solid waste management system of SCC is not effective and adequate. The study encompasses on an in-depth analysis of the present condition of waste management system of selected Health Care Centers (HCCs) in SCC and an assessment has been performed for the improvement of hospital sanitation situation. It is observed that the average waste generation rate for hospitals and clinics (HCC-A) is 0.934 kg/bed/day, which is much higher than that (0.0414 kg/capita/day) for diagnostic center and out door clinics (HCC-B). The percentage of hazardous waste produced in the ‘HCC-A’ is 22.92 where as that for ‘HCC-B’ is 36.03. These portions of hazardous wastes require special attention.  The remaining portions of waste can be easily disposed off into the municipal dustbin if they are carefully segregated. A color-coding system and storage container has been recommended for segregating HW effectively. The average generation rate (kg/bed/day) of HW of Sylhet city is close to that of Dhaka city, but much lower than that of developed countries like USA, Netherlands and France. However, the percentage of hazardous waste of SCC is close to Germany and Dhaka city but much higher than that of Netherlands, Sweden and lower than that of Denmark and USA.

 
 
 
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Title:

Assessment of population exposure risk and risk zones due to surface water quality by GIS- a case study on Sylhet

Author (s):

Md. J. B. Alam, Mohammad S. Rahman and M. H. Hossain

Abstract:

A study on the risk assessment due to contaminated surface water system of Sylhet municipality was carried out through analysis of some selected water quality parameters. The parameters considered were Dissolved Oxygen (DO), pH, BOD5, arsenic (As) and iron (Fe) content of water. The DO concentration of most of the samples were more than 6 mg/l and all the samples have higher values of BOD5 than 100 mg/l. Fe content of all of the samples were above 0.3 mg/l. About half of the population (47.02%) comes under very bad quality of surface water and it constitutes about 47.28% of total area. Only 30.12% of population is living in the area (31.75%) having medium quality of surface water. Again 22.86% of population is living in the area (20.97%) having bad quality of surface water. About half of the population (55.22%) comes under very high-risk zone.

 
 
 
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Title:

Analysis for adopting logical channel section for 1d dam break analysis in natural channels

Author (s):

Mimi Das Saikia and Arup Kumar Sarma

Abstract:

The objective of this study was to predict and analyze the dam break flood in a real river valley. A numerical model was developed for simulating dam break flood and applied for analyzing flood situation due to the instantaneous hypothetical failure of the proposed dam in river Dibang, a major Himalayan tributary of the River Brahmaputra. Significant variation in bed slope, bed width and resistance characteristic along the channel length are the typical characteristics of Dibang river. To compute the flood under such dam failure conditions, natural channel is generally represented by a simplified channel. . Such simplification may lead to erroneous estimation of the important parameters such as maximum probable depth, peak arrival, maximum probable velocity and inundated area. Therefore, due emphasis should be given in the selection of an appropriate computational channel while simulating a real dam break flood. Two different approaches for adopting the computational natural channel have been proposed here for predicting the dam break flood. Probable maximum depth of flood, time of peak arrival and the maximum probable flood velocity at different sections up to 63 km downstream of the proposed Dibang dam have been computed . In one approach, the predictions are made by adopting a computational channel, which considers the whole floodplain downstream of the dam when River Dibang enters the plain. The other approach considers only the original simplified river channel of Dibang. The predictions of dam Break Wave Propagation by both the methods have been compared and analyzed. The analysis clearly illustrates the importance of the proper selection of the computational channel in a river valley downstream of the dam to avoid over estimation or underestimation of flood.

 
 
 
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Title: Water supply and sanitation (WATSAN) condition of the Chaptir Haor wetland in Bangladesh
Author (s):

Mushtaq Ahmed, Rezaul Kabir Chowdhury, S. Z. Farzana and Md. A. Islam

Abstract:

People of wetland areas in Bangladesh are very accustomed to live with various constraints. Chaptir Haor wetland, which is located at Derai Thana of Sunamganj district, has been selected for identifying water supply and sanitation conditions of wetland people. Extensive field survey was carried out during September 2005 in five selected areas of the wetland namely Chandpur, Karimpur, Srenarayanpur, Halimpur and Tarol. PRA method primarily aimed in focus group discussion has been followed in the survey work. Study reveals that 100% people use tube well water and river water respectively for drinking and domestic purposes. Commonly used defecation practices have been categorized as open defecation, hanging latrines, offset pit latrine and some sanitary latrine. About 15%, 50% and 60% people of Srinarayanpur, Tarol and Karimpur are found to use sanitary latrines respectively. This figure is only 5% for Chandpur and Halimpur.

 
 
           
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