A review on conventional and laser assisted machining of Aluminium based metal matrix composites

Aluminum based Metal Matrix Composites (Al-MMC) have been found in different industrial applications due its excellent properties compared to conventional materials. Machining of these composites is difficult due to the hard particle reinforcements. The wider usage of these composites is limited due high machining cost and excessive tool wear with conventional machining. Because of increasing demands in industries, any improvement of conventional machining process or any other deployment of additional technique is directly related to higher productivity. Laser Assisted Machining has become an effective alternative to the conventional machining of these difficult- to- cut materials. This paper provides an overview of conventional machining of MMCs and the potential of LAM. An attempt is made to give a better understanding of the operating conditions such as machining parameters and Laser parameters. Finally, the summary of the review is discussed and the scope for future research is presented

Evaluation of sanguineous and crystalloid cardioplegic solutions during total heart-lung bypass in dogs

Twenty-four mongrel dogs were subjected to sanguineous and crystalloid cardioplegia for a period of thirty minutes at 20°C and 25°C systemic hypothermia during cardiopulmonary bypass. Cardioplegic solutions were administered at 4°C to induce cardioplegia. Physiological functions of the myocardium revealed that the cardiac function returned to normal sinus rhythm without any loss when blood cardioplegic solution was used at both hypothermic temperatures. The time taken for cardioplegia and cardiac electrical quiescence was achieved earlier at 20°C. Animals in sanguineous cardioplegic group revealed better functional return and revival of cardiac musculature in terms of lesser applications of defibrillator, lesser requirement of inotropic support and early cardiac contraction. This study revealed that sanguineous cardioplegic solution at a systemic temperature of 20°C was found to afford better myocardial protection during an arrest period of 30 minutes

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

OPTIMIZATION OF MACHINING PARAMETERS FOR TURNING AL-SIC (10P) MMC USING TAGUCHI GREY RELATIONAL ANALYSIS

This paper presents the detailed experimental investigation on turning Aluminium silicon Carbide particulate Metal Matrix Composite (Al-SiC &ndash;MMC) using polycrystalline diamond (PCD) fine grade insert. Experiments were carried out on a medium duty lathe. A plan of experiments, based on the techniques of Taguchi, was performed. Analysis of variance (ANOVA) is used to investigate the machining characteristics of MMC (A356/10/SiCP). The objective was to establish a correlation between cutting speed, feed and depth of cut with the specific power and surface finish on the work piece. The optimum machining parameters were obtained by using grey relational analysis for minimum power consumption and better surface finish. Finally, confirmation tests were performed to make a comparison between the experimental results and developed model

The Effect of Anthropogenic Heat and Moisture on Local Weather at Industrial Heat Islands: A Numerical Experiment

The current study addresses the role of heat and moisture emitted from anthropogenic sources on the local weather with the aid of numerical weather prediction (NWP). The heat and moisture emitted by industries to the atmosphere are considered main sources in this study. In order to understand the effect of heat and moisture on local weather, the study is conducted to capture the impact of heat with no moisture change. The results are compared against a control run case without perturbation and also against the case where both heat and moisture are perturbed with temperature as a single parameter. The Angul district in Odisha that houses over 4000 industries is considered our study region. The numerical simulations are performed using the mesoscale Weather Research and Forecasting (WRF) model for two rain events, namely a light rain case and a heavy rain case, with different physics options available in the WRF model. The WRF simulated maximum rainfall rate using various microphysics schemes are compared with the Tropical rainfall measuring mission (TRMM) observations for validation purposes. Our study shows that the WDM6 double moment microphysics scheme is better in capturing rain events. The TRMM-validated WRF simulation is considered a reference state of the atmosphere against which comparisons for the perturbed case are made. The surface temperature is perturbed by increasing it by 10 K near the industrial site and exponentially decreasing it with height up to the atmospheric boundary layer. A numerical experiment represents heating without addition of moisture by recalculating the relative humidity (RH) corresponding to the perturbed temperature. The perturbed temperature affects sensible heat (SH) and latent heat (LH) parameters in the numerical experiment. From the results of the numerical investigation, it is found that the near-surface rainfall rate increases locally in a reasonable manner with the addition of sensible heat to the atmosphere. A comparison against the case where moisture is added shows that enhanced rainfall is more sensitive to sensible and latent heat than sensible heat alone

Sodium alginate potentiates antioxidant defense and PR proteins against early blight disease caused by Alternaria solani in Solanum lycopersicum Linn.

The use of biopolymers as elicitors in controlling plant diseases is gaining momentum world-wide due to their eco-friendly and non-toxic nature. In the present study, we have used an algal biopolymer (sodium alginate) and tested its applicability as an elicitor in inducing resistance factors against Alternaria solani, which causes early blight disease in Solanum lycopersicum (tomato plant). We have pre-treated tomato plants with different concentrations of sodium alginate (0.2%, 0.4%, and 0.6%) before A. solani infection. We found that sodium alginate has effectively controlled the growth of A. solani. In addition, a significant increase in the expression levels of SOD was observed in response to pathogen infection. The increased protease inhibitors activity further suggest that sodium alginate restrict the development of A. solani infection symptoms in tomato leaves. This corroborates well with the cell death analysis wherein increased sodium alginate pre-treatment results in decreased cell death. Also, the expression profile analyses reveal the induction of genes only in sodium alginate-pretreated tomato leaves, which are implicated in plant defense mechanism. Taken together, our results suggest that sodium alginate can be used as an elicitor to induce resistance against A. solani in tomato plants

MACHINING OF Y2O3 REINFORCED MAGNESIUM RARE EARTH ALLOYS USING WIRE ELECTRICAL DISCHARGE TURNING PROCESS

Machining Science and Technology262160-18

High-temperature, polymer-graphite hybrid composites for bipolar plates: effect of processing conditions on electrical properties

High-temperature thermoplastic–graphite composites are prepared using polyphenylene sulfide (PPS) and polyether sulfone (PES) containing natural graphite powder. All samples are prepared by high pressure compaction and heating to high temperatures. The effect of a third additional conducting component on the electrical resistance of these composites is studied. A low resistance of the order of 0.1 Ω can be obtained even for a graphite concentration of 50% by addition of the third component. The effect of a mixing/blending technique on the anisotropy of conductivity is investigated. Solution blending of PES with graphite leads to lower anisotropy values than powder mixing and compression moulding. The samples when exposed continuously to a working temperature of 100 °C give a small but significant reduction in electrical resistance. X-ray diffraction studies on composites prepared by different techniques indicate that there is restructuring and crystallite re-orientation of the graphite phase in the samples. A large reduction in the crystallite size is observed for samples prepared by solution blending while re-orientation occurs after heat treatment. The changes in electrical properties can be correlated with these structural transformations in the composites