Mechanical Engineering

The study has been done on the basis of questionnaire survey in the twenty-degree engineering colleges from West Bengal and foreign countries by random selection, ten colleges from each to measure the current or baseline performance level. The feedback for this questionnaire survey has been considered independently for service providers such as administrators, faculties, other supporting staff as well as students who receive these services and are direct customers. A total of 2168 persons have been surveyed from the 20 colleges. The baseline or current performance level of the colleges has been assessed based on the sigma level through quantification of the survey questionnaire consisting of eight enablers. Each enabler contains several questions or drivers. A seven-point scale has been designed for each driver ranging from “Unsatisfactory” to “Outstanding”.

In the present work, an effort has been made to investigate the effect of welding parameters on bead geometry. Mathematical models were developed by using 2- level half factorial technique to predict the bead geometry within the range of control parameters or operating variables for single wire submerged are welding. The models developed can be employed easily in automatic or robotic welding, in the form of program, for obtaining the desired high quality welds. Current, open circuit voltage, welding speed and nozzle-to-plate distance were taken as welding variables constant. The models were developed from the observed values, with the help of design matrix.  It was found that penetration increases significantly with current, decreases with welding speed and remains unaffected by open circuit voltage & nozzle to plate distance. Reinforcement was found to increase with current and decrease with open circuit voltage, welding speed and there is no effect by nozzle to plate distance. Weld bead width was found to increase with open circuit voltage, decrease with welding speed; but ‘w’ increases with increase in nozzle to plate distance. The adequacies of the models were tested by use of analysis of variance technique and signification of coefficients was tested by student’s-test’. The combined and main effect of different parameters involved has been presented in graphical form.

A numerical investigation of the vortex shedding past a circular cylinder in a two- dimensional channel of varying height is presented in the term of Strouhal number by solving continuity and momentum equations using FLUENT 6.3. The computational grid structure is generated by using Gambit. In this work, the result is carried out with blockage ratio b=0.83, 0.85, 0.88.

Analysis of Reversed Hazard Rate (RHR) can provide insights in making it suitable for industrial applications. From the published literature it is learnt that Nature of reversed Hazard rate for standard continuous distributions is a decreasing function. Obviously this makes RHR suitable in the field of maintenance engineering to address hidden failures in a given system. One of its most useful applications lies in the assessment of waiting time of hidden failures. RHR is closely related to another important concept known as the mean waiting time. This concept is useful in casualty insurance, reliability, and medicine including forensic science to predict times of occurrences of events. For instance, the incubation times of diseases, are difficult to measure because the infection time is unobserved in general. Mean waiting time will offer its great help in such situations, which are analyzed and incorporated appropriately in this paper.

The dynamic behavior of infrastructure development has opened a wide area for research in construction management in general, and maintenance management in particular, globally. Ready mix concrete, which is mostly preferred nowadays, is loaded in a transit mixer, and is transported to the construction site. The concrete is delivered to the construction point by means of a concrete pump. Life of the concrete pump can be enhanced and hence capacity of the plant using effective preventive maintenance. In this paper, optimal time for replacement for some critical components has been established using the approach of reliability centered maintenance. The paper includes the reliability assessment and the details of the effectiveness of maintenance on the system under investigation are reported in the paper.

For efficient heating with lesser fuel consumption and a quick way of heating, oxyfuel has been clearly shown to produce very low emissions of CO2 and NOX as compared to air-fuel for 15 years. Among oxyfuels, flameless oxyfuels can be even more economical and technically superior for higher production rates, excellent uniform heating and very low NOX emissions. In the present study, our casting centres have accommodated a number of reheating furnaces along with preheating stands working on flameless oxyfuel to 1 tonne capacity of smallest size ladles. Flameless oxyfuel has improved to a greater uniformity in heat distribution and decreased fuel consumption approximately by 30-65% compared to air-fuel mixture. It also falls to low NOX emission during high levels of ingress air, which is essential for economical use. In this work it lowered scaling losses, refractory wear during reheating and ladle preheating respectively by improving the steel quality to be produced during casting. It is also seen that for low calorific value (below 7-7.5 MJ/Nm3) gases such as top gas released from the furnace, use of oxyfuel combustion is an absolute requirement. With the advances in today’s technology, combining air-fuel and flameless oxyfuel can create semi-flameless combustion without replacing the air-fuel burners. The paper highlights the working of flameless oxyfuel and its application and also presents the results that have been achieved in controlling pollution and consumption.

The main purpose of this paper explore a method for determining the radial cutting forces during drilling and power spent on cutting, analytical way. Inspect and acquire the skills to work with reference books.which improved the tools efficiency .where not balanced radial components of the cutting forces ?fy, was found to specified the analytical dependences components of cutting forces. Calculations show that the vibrations of unbalanced force ?fy commensurate with magnitude fy radial component of the cutting force, and sometimes exceed this force.

An analytical study is performed to study the effects of thermal radiation and chemical reaction on unsteady free convection and mass transfer of a viscous incompressible fluid past an accelerated infinite isothermal vertical plate in the presence of magnetic field. The fluid considered here is a gray, absorbing/ emitting radiation but a non-scattering medium. It is assumed that the effect of viscous dissipation is negligible in the energy equation and there is a first order chemical reaction between the diffusing species and the fluid. The dimensionless governing coupled linear partial differential equations are solved using the Laplace transform technique. The influence of the various parameters, entering into the problem, on the velocity field and temperature field is extensively discussed with the help of graphs.

Ultrasonic waves are used widely in food production, industry and chemical reactions. For conducting such a reactions, it is need to have a reactor in which liquid is affected by the waves. Among the most important parameters used for reactor design, the reactor dimensions may be considered as the most important parameter that can take influence the most, from the wave cavitation. In this study, effects of ultrasonic power, horn diameter and horn height on the amount of energy absorbed by liquid in reactor were evaluated and models were further developed for estimating the absorbed energy. Statistical analysis indicated that the effects of input power, reactor diameter and reactor height were all significant on energy absorption (P<0.01). The results revealed that as the horn diameter increased from 70 to 100 mm, 9% decrease was occurred in the absorbed energy. By increasing the horn height from 30 to 70 mm, 11% decrease was observed in the energy absorption. There was an 11% increase in the energy, together with an increase in ultrasonic wave power from 100 to 300 W. It was also concluded that the second order model was most suitable to predict the amount of energy absorbed by liquid (R2=94.5%).

The aim of this study was to establish the relationship between the Stature and Popliteal Height Sitting, PHS. 161 male occupational bus drivers were randomly selected for anthropometric characterization of Stature and PHS using standard measuring equipment. The data were analyzed using SPSS 16.0 and Design-Expert 6.0.8. Then regression model was used to estimate PHS. The model shows that there is a linear relationship between the Stature and PHS with coefficient of determination (R2) of 0.8258 (p < 0.0001). The model mitigates time required for gathering anthropometric data. Designers would find this as a huge working tool for adequate productions.