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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
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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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