Mechanical Engineering

This paper presents a hybrid optimization approach for the determination of the optimum laser welding process parameters which minimize the weld bead width and maximize weld bead depth together in pulsed Nd:YAG laser welding of thin plates of SS 304 having thickness 2.9 mm. An exhaustive experimental study has been conducted with various process parameters like, pulse width, pulse height, stand-of distance, frequency, welding speed, gas flow angle and gas flow rate. Each of the parameters has three levels. Thus, an orthogonal array L18 has been adopted to accommodate all the above factors at their respective levels. The weld bead width and the weld bead depth are considered as process performances. A multi-response optimization has been carried out by using grey relational analysis (GRA). Also the significant process parameters have been found out for the above process optimization by performing an ANOVA.

The present research is motivated by the changing roles of continuous improvement programs as a result of changes in organizational environments. Focus on the changing demands made on organizational infrastructure for continuous improvement program is under consideration. Visual process control is applied in a financial section of a company. The success of Six Sigma programs depends to a large extent on motivating employees, training them and coordinating their efforts in projects as well as implementing changes resulting from projects. Managers are interviewed (Total 12) and on the basis of score the improvement are analyzed.

The growing concern due to environmental pollution caused by the conventional fossil fuels and the realization that they are non-renewable have led to search for more environment friendly and renewable fuels. Among various options investigated for diesel fuel, biodiesel obtained from vegetable oils has been recognized world over as one of the strong contenders for reductions in exhaust emissions. In this present experimental work is carried out the performance and emission characteristics of diesel and biodiesel (Mahua) is analyzed. The results of depicts B20 Mahua blend of biodiesel is having the better characteristics in terms of performance and emission.

Surface texturing by fabricating micro dimple on a surface have been proven to be very effective to improve tribological performances of sliding surfaces. Studies and research shown that micro-dimple reduced friction coefficient significantly and increase the service life of artificial hip replacement. This study aim to investigate and to compare the wear factor between four different micro-dimpled dimensions which comprise diameter, depth and pitch. The main objectives are firstly to determine parameter to fabricate micro-dimple surface, secondly to optimise surface micro-dimple pattern and finally to determine surface characterisation. Four samples have been chosen with different dimple parameter. In this experiment, pin-on-plate wear test machine was used. The result shown that wear factor at the pin for pattern 1 (1.53905 x 10-6 mm3/Nm), pattern 2 (1.50764 x 10-6 mm3/Nm) and pattern 3 (1.61234 x 10-6 mm3/Nm) were compatible with result done at the same test rig at Newcastle University, where else result for pattern 4 (3.66440 x 10-6 mm3/Nm) slightly off for varies reasons. On the other hand, there are no significant mass loss at the plates although the surface roughness of the plates have record changes. Conclusion from the experiment is wear factor from less dense micro-dimple is lower than wear factor in denser micro-dimple.

The primary goal of TPM (Total Productive Maintenance) programme is to change the culture of the company’s maintenance policy by involvement of all employees toward the maintenance system of the company. The present paper aims to reduce unplanned stoppage, breakdown the accidents and losses obstructing equipment effectiveness. Prior to induce the TPM in the industry a review is being done by researcher and real time Overall equipment effectiveness is measured and shown to management of companies. Real time TPM is being implemented for an effective maintenance of the company and consecutive six month data is collected to see the change. Due to effective maintenance and employee involvement for one purpose has enforced the management for continuous improvement in the company through the systematic implementation of TPM.

This paper deals with demand prediction by combining basic exponential smoothening with Markov based algorithm. This demand prediction is suitable for novel and minimum shelf life products and is suited for small scale retailers and manufacturers, since for them acquisition of costly software tools is out of their financial reach. This paper attempts to arrive at predicting a fixed value of demand which will enhance the profit. The Exponential smoothing process involves comparing the latest observation with the previous weighted average and making a proportional adjustment, governed by the coefficient ?, known as the smoothing constant. By convention we constrain the coefficient to the range, so that only a part of the difference between the old mean and the new observation is used in the updating, 0<?<1.Initially demand is predicted by using basic exponential smoothing for two successive months and error of demand for each day is estimated. Markov based algorithm is then applied for these errors and the steady state probability is then determined for each state. The demand corresponding to the state with maximum probability is taken as the optimum one and the corresponding profit is estimated. This concept is then implemented for a baked product and the annual savings for a particular product is then established.

In the present work experimental setup is planned, designed and fabricated for the study on jet impingement heat transfer on flat and curved surfaces of radius of curvature 0.5, 0.725, 1.3. Experiment was conducted for the varying Reynolds number of 3500, 5500 and 9000. The heat transfer characteristics of a slot jet obtained from nozzle designed is impinged on concave and flat surfaces with constant heat flux have been analyzed experimentally. The effects of surface curvature R/L, the dimensionless nozzle to surface distance and Reynolds number on average Nusselt number of plate is obtained. It is found that Reynolds number has greater influence on heat transfer from the plates as the H/W ratio varies. The findings of the present study can be utilized to investigate the curvature of the blade for which heat transfer is more and to optimize the cooling rates in the surfaces for the better design of the gas turbine blades.

This paper describes the study of coefficient of thermal expansion (CTE) of as-cast and heat treated aluminium 7075 alloys. These alloys were subjected to different aging durations. The stir casting technique is used to prepare the specimens. These specimens were machined in accordance with ASTM standards followed by heat treatment process. All the specimens were aged to different periods of 1hr, 3hr, 5hr at an aging temperature of 175 oC. Coefficient of thermal expansion tests were performed in both as-cast and heat treated conditions. In each case the coefficient of thermal expansion values were found to increase with increase in aging durations. Solution heat treatment at 530 oC followed by artificial aging at 175 oC found to increase in dimension change of every specimen tested. The coefficient of thermal expansion curves exhibited some residual strains, which were decreased with the increase in aging durations.

The Islamic civilization paid great attention to mechanical engineering during the medieval centuries. The mechanical engineers of the Islamic Empire gave outstanding attention to measurement instrumentation including balances and astrolabes. They used balances to adjust commercial activities in the society and for engineering purposes. They succeeded to use the balance in determining the specific weights of both solids and liquids, examining the purity of precious materials and examining the constituents of alloys. They developed the Greek astrolabe and discovered hundreds of applications required by their daily life. They also devised different type of astrolabes such as the planispheric, quadrant and spherical astrolabes. They wrote 100's of manuscripts explaining the design and use of the astrolabe where some of them still surviving up to now in a large number of libraries and museums around the world. The paper discusses the contribution of Islamic scientists to the development and application of balances and astrolabes.

For the appraisal of contamination of lake waters coliform count is generally used to review the infectivity echelon of potable water. The usual sources of coliform contamination at lake Sambhaji include discharges due to domestic wastes, laundry activities related to hospitals, natural surface runoff, rivulets, swimming activities, anthropogenic activities urban run-off, animal and human wastes. Lake water for the reason it had objectionable odour, was suspected for being contaminated. An attempt was made to comprehend the potable competence lake waters of lake Sambhaji, at Solapur district (MS), India, by specifying total coliforms counts employing the method of Multiple Tube Test with double strength MacConkey Broth Medium (Himedia M539S), the traditional method for presumptive isolation of coliform bacteria by MPN, incubating at 370C for 24 hours, in addition to other tests. Most Probable Number (MPN) of total coliforms was determined by referring to standard probability table for estimation of total coliforms for the determination of MPN. The investigation of the cultural response revealed 480 cfu/ml at site 2 and 220 cfu/ml at site 1, exceeding limits for recreational water. The highest fraction of indicator coliforms was detected in the water sample at site 2, of lake Sambhaji which has truly objectionable odour as compared to site 1 of lake Sambhaji. Taking into consideration the observations of high coliform count at lake Sambhaji results portray a tragic testimony of the deterioration of the ecological health of the lake and advocates dismissal of the consideration of water for being thought for its potable potential, portraying human malady if exposed to such unsanitary lake. The results encompass imperative repercussion directing prioritization to design restoration strategies.