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ARPN Journal of Engineering and
Applied Sciences June 2006 | Vol.1 No. 1 |
Title: |
Effect of Cryogenic Cooling by Liquid
Nitrogen Jet on Tool Wear and Product Quality in Turning AISI-9310 Steel |
Author (s): |
N. R. Dhar and S.
Islam |
Abstract: |
Growing demand for higher material removal rate (MRR) in machining
necessitated much increase in cutting velocity, which eventually
required the efficiency of cooling to be increased in order to cope with
the increase in the cutting temperature. Cryogenic cooling by liquid
nitrogen jet is a promising new technology in high production machining
which economically addressed the current process environmental and
health concern. High production and finish machining are inherently
associated with generation of intense heat and cutting temperature at
the cutting zone. Such high cutting temperature not only reduces tool
life but also impairs the surface integrity of the job. So the
temperature at the cutting tool interface is one of the important
factors influencing the machining process while primarily dependent on
the cutting speed and the work piece material properties as well as
cutting tool performance. The present paper deals with experimental
investigation in the role of cryogenic cooling by liquid nitrogen jet on
cutting temperature, tool wear, surface finish and dimensional deviation
in turning of AISI 9310 steel by coated carbide insert (SNMG). The
results have been compared with dry machining. The results of the
present work indicate substantial reduction in tool wear, which enhanced
the tool life, dimensional accuracy and surface finish. This may be
mainly attributed to reduction in cutting zone temperature and favorable
change in the chip‑tool interaction. |
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Title: |
An Elementary model to study sensitivity
of the departure from Nucleate Boiling Ratio (DNBR) to perturbations
in Nuclear Reactor Systems
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Author (s): |
Zafar-Ullah Koreshi |
Abstract: |
The heat flux in a
water-cooled nuclear reactor system is used to estimate the Departure
from Nucleate Boiling Ratio (DNBR) of the system which is an important
engineering design parameter for nuclear reactors. The DNBR signifies an
operational safety limit. During normal operation, there may be
fluctuations in, for example, the power of the reactor, which can affect
the temperature distribution along a coolant channel which may
subsequently result in boiling leading to a reduction in heat transfer.
This may further cause variations in the DNBR, which may reduce the
safety margin requiring immediate remedial action. This work quantifies
the sensitivity of the DNBR, and the location of the minimum DNBR due to
power fluctuations obtained from a steady-state energy balance using
radial heat conduction and convection. Results are presented for a
reference PWR of 1893 MW(th). A future study will use the same analysis
for the 300 MW(e) Chashma Nuclear Power Plant (Chasnupp). |
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Title: |
FATIGUE PROPERTIES OF
SMOOTH AND AS-SHOT PEENED N BEARING AUSTENITIC STAINLESS STEELUNDER
TENSION-TENSION CONDITION |
Author (s): |
A.
Onizawa, M.A. Islam, M. Ojima and Y. Tomota |
Abstract: |
The
fatigue properties of solution treated (ST) high nitrogen austenitic
stainless steel (RS561) have been compared with a commercially available
standard austenitic stainless steel (SUS310S) before and after shot
peening. For doing this tension-tension fatigue tests were carried out
at 5Hz and 22Hz frequencies at room temperature in air. In order to know
the shot peening effects, half of the specimens of both steels were shot
peened (SP). As per the experimental results, addition of nitrogen
significantly improves the fatigue life and changes the fatigue fracture
morphologies of the stainless steel, whereas frequency was found to have
no marked effect on the fatigue lives. Shot peening have been found to
increase the fatigue limits and change the fracture mechanisms of both
steels. However, the increase in the fatigue limit in high nitrogen
steel is much lower than that of the SUS310S steel. At high applied
stress levels, effect of shot peening was found to disappear for both
steels. |
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Title: |
Design and
Calibration of a Direct Mounted Strain Gauged Lower Links System for
Measurement of Tractor-Implement Forces
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Author (s): |
R.J. Godwin, J. Kilgour, B.S. Blackmore |
Abstract: |
A bi-axial direct mounted strain gauged lower links
system for the measurement of tractor-implement forces was designed and
calibrated for coincident and perpendicular loads up to 10 kN. The system was tested for its
Sensitivity, Cross-Sensitivity, Hysteresis, Linearity and Repeatability.
The results of the calibration tests revealed that the system was well
working for a range of draught and vertical forces up to 20 kN. The
results showed a high degree of linearity between bridge output voltage
and force applied. The minimum co-efficient of correlation, R2,
was found to be 0.9996. The hysteresis effect between the calibration
curves for increasing and decreasing applied coincident and
perpendicular force was very small (<1.20%). The interactions of the
applied forces on the orthogonal force bridges were less than one
percent. Maximum difference from the mean value for applied coincident
and perpendicular force respectively was 1.75% and 1.3%. The system could best be used for the measurement of draught
(horizontal) and vertical forces where medium type equipment is attached
with a tractor. |
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Title: |
Design of a Low Cost
Multi Channel Data Logger |
Author (s): |
Sumon Saha, Md.
Tofiqul Islam and M Zakir Hossain |
Abstract: |
Development of a
low-cost multi-channel (eight to twenty two channels) data logger can
easily be made and easily be used to convert the analog signal of
physical parameters of various tests or other purposes of engineering.
By a suitable program code it can be used to read the value digitally
with a PC. Our aim is to provide with a module and a software package
when installed in a computer, one can remotely acquire and monitor
several numbers of the same or different types of signals sequentially
at a time. Signals obtained from various sensors have been effectively
conditioned. Now interfacing these signals using an ADC with the
parallel port of a computer satisfies the very goal of data acquisition.
The user friendliness and reliability in using a PC and channel selector
multiplexers further add to the versatility of the data logger. Design
and implementation of such equipment cost only at US$30, makes it very
inexpensive comparative to other commercially available data loggers. |
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Title: |
STUDY ON CONNECTION
BETWEEN PRECAST CONCRETE BEAM AND CAST-IN-SITU COLUMN IN PREFABRICATED
BUILDING FRAMES |
Author (s): |
Tazeen
Fatema and Md. Toihidul Islam |
Abstract: |
As a
structural system prefabrication is very efficient in terms of cost,
time and quality, but suffers a major setback in connection, which is an
important design and construction factor. A mathematical model capable
of analyzing multistoried building frames incorporating semi-rigid
beam-column connections has been developed. The model is linear type and
iterative in nature developed for multistoried building frames with
connection, which is based on maximum end moment of frame. A
mathematical relationship is developed and used for analysis and design
of joints of a particular type. The linear moment-curvature (M-θ)
relationship for this particular type of connection has been formulated
by using elementary solid mechanics. Using this relationship
investigations have been carried out to study the behavior of precast
building frame such as connection flexibility and its effect on internal
distribution of forces, lateral drift, joint rotation etc. A parametric
study with the connection is also carried out. Finally a tentative
recommendation regarding the use of the particular type of joint between
precast beam and cast-in-situ column is made. |
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Title: |
CRITICAL ASSESSMENT
OF THE DEGREE OF TEMPER EMBRITTLEMENT IN 2.25Cr-1Mo STEEL |
Author (s): |
M.A.
Islam |
Abstract: |
Reversible temper embrittlement has been frequently observed in many
different low alloy steels, serving at high temperatures, due to
segregation of trace elements at grain boundaries and/or carbide/matrix
interfaces. This type of impurity element segregation can severely
deteriorate the toughness and fatigue properties of the steel. In
general, increase in the hardness and tensile strength also increases
the fatigue life of the steel. So, fatigue lives of steels are sometimes
assessed by these parameters. In this research work 2.25Cr-1Mo steel,
before and after temper embrittlement, was characterized by
microstructure observation, hardness measurement, tensile, fatigue and
fracture toughness tests at room temperature in air. Experimental
results revealed that temper embrittlement hardly modify the room
temperature hardness values and tensile properties, although the fatigue
and fracture behaviours of this steel are significantly changed.
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Title: |
Formulation of a General Risk Assessment Framework for the Water Related
Disasters of Bangladesh |
Author (s): |
Rezaul
Kabir Chowdhury |
Abstract: |
Bangladesh is a disaster prone area. Most of the disasters are water
related such as flood, drought and water scarcity, cyclonic storm surge
and river erosion. Almost every year the country faces severe
catastrophic natural hazards. Risk assessment plays a vital role for
planning proper risk reduction measures. Currently, the country has no
risk assessment framework that provides a basic guideline for risk
assessment to the planners and policy makers. In this study, a general
risk assessment framework has been developed for the country. Various
steps of risk assessment and options of risk reduction have also
delineated in the paper. |
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