Welding

Friction welding method is one of the most simple, economical and highly productive methods in joining similar and dissimilar metals. It is widely used in the automotive, aircraft and aerospace industrial applications. For many applications it is often necessary to join aluminium (6061) to make finished part. In this project the main aim is to weld the small thickness of aluminum (6061) plates for that friction welding machine used is of higher cost. Here the aim is reduce the cost of friction welding machine with simple parts like three phase A.C induction motor, bush, frame stand, friction tool, universal vice, vertical moving bed, horizontal moving bed, etc. The result expected would be of same strength as that of old friction welding machine. It is very easy and at same time production time is very much reduced. This machine is best suitable for mass production

Carrier relaxation dynamics in InP quantum dots studied by artificial control of nonradiative losses

A method to study carrier relaxation dynamics based on the artificial control of nonradiative losses by an external electric field is proposed. Clear evidence of phonon-assisted relaxation as the main relaxation mechanism of hot electron-hole pairs in InP self-assembled quantum dots is found by applying the proposed method. Efficient one-step relaxation processes with emission of acoustic and optical phonons are observed. These findings give important insights into the interaction of the electron-hole pairs in quantum dots with the phonon subsystem

Anisotropic optical response of InP self-assembled quantum dots studied by pump-probe spectroscopy

Transient anisotropic reflectivity change spectra of InP quantum dots have been observed by means of two-color pump-probe spectroscopy. The results show a fast decay component with a lifetime of 100–200 ps which depends on the probe energy, followed by the slow decay component of ~1 ns. The reflectivity change spectra have a dispersive shape having a maximum on the higher energy side of the photoluminescence (PL) band by 80 meV, and a dip located at the maximum of the PL band. Interestingly, the reflectivity change signals observed for the [1[overline 1]0] and [110] polarizations have the opposite sign when the probe energy is set between the first and second exciton states. The temporal change of spectra is simulated by means of a Monte Carlo method, and the model is found to well reproduce the experimental result. Further, the model enables us to evaluate the microscopic exciton parameters of single quantum dots by macroscopic observations. The oscillator strengths along the [110] and [1[overline 1]0] directions at the PL peak energy are evaluated to be fx=0.37 and fy=0.71, respectively. The oscillator strength is about five times smaller than simple theoretical estimates. This suggests a small overlap of the envelope functions which is consistent with the existence of a permanent dipole moment observed in these QDs

Phonon resonances in photoluminescence spectra of self-assembled quantum dots in an electric field

Phonon resonances observed in the photoluminescence (PL) spectra of InP and In0.35Ga0.65As self-assembled quantum dots (QD’s) in an external electric field are studied in detail. The resonances are shown to arise from fast phonon-assisted relaxation of hot carriers, and to become observable when the PL is quenched by nonradiative losses from excited states. A simple model is developed that considers tunneling of the carriers from the QD’s into the barrier layer as the main process responsible for PL quenching in the presence of an electric field. From this model, the depth of the potential well for holes is estimated to be 10–20 meV for the InP QD’s. The PL kinetics measurement is performed with a time resolution of 6 ps. Clear evidence of surprisingly fast carrier relaxation with emission of high-energy acoustic phonons is found. Further acceleration of the carrier relaxation is observed under strong optical pumping. We consider this effect to be caused by Auger-like carrier-carrier scattering processes. Acceleration of the relaxation observed at elevated temperatures is ascribed to stimulated phonon emission

Review on mathematical models for the prediction of solar radiation

Global Solar Radiation (GSR) data is important for all solar energy based applications, mainly to forecast the output power of solar PV system in case of renewable energy integration in to the existing grid. The solar radiation components are measured using pyranometer, solarimeter, pyroheliometer and so on. It is not practically possible to install this radiation measuring instruments at all the locations due to the cost and difficulty in measurements. Hence the availability of solar radiation data is limited to few meteorological stations especially in the developing country like India. Therefore, it is necessary to develop mathematical models to predict the solar radiation to eliminate the costly pyranometer. In this paper, the review of mathematical models using trigonometric functions for the prediction of global solar radiation is presented. The mathematical models are applicable wherever the radiation data is unavailable. From the review results, it is concluded that mathematical model with both sine and cosine wave equation gives good prediction accuracy with correlation coefficient of 0.9

Predictors of Malignancy in Chronic Pancreatitis.

INTRODUCTION : Chronic pancreatitis is a condition characterised by irreversible destruction and fibrosis of the exocrine parenchyma, leading to exocrine pancreatic insufficiency and progressive endocrine failure leading to diabetes. Alcoholic chronic pancreatitis is the commonest type of chronic pancreatitis seen in the western world, while in the tropics there is a distinct non-alcoholic type of chronic pancreatitis of uncertain aetiology, which is far more common. Several names have been proposed for this type of chronic pancreatitis including tropical chronic pancreatitis (TCP), tropical calcific pancreatitis, juvenile pancreatitis syndrome, Afro-Asian pancreatitis, and fibrocalculous pancreatic diabetes. TCP can be defined as a juvenile form of chronic calcific non-alcoholic pancreatitis prevalent almost exclusively in the developing countries of the tropical world. Some of its distinctive features are younger age at onset, presence of large intraductal calculi, an accelerated course of the disease leading the end points of diabetes and/or steatorrhoea, and a high susceptibility to pancreatic cancer. Kini reported the first case of pancreatic calculi from India in 1937 and this was followed by reports of pancreatic calculi observed at postmortem from Vellore in southern India. However, it was after Geevarghese, one of the pioneers in the field, documented one of the largest series in the world from Kerala state in Southern India that TCP attracted International attention. AIM OF THE STUDY : The aim of the study was to A. Prospectively analyse the mass lesion arising in the background of chronic pancreatitis clinically, biochemically & radiologically. B. To identify the predictors of malignancy in patients with chronic pancreatitis without a tissue diagnosis. METHODS : Between August 2004 to February 2007, 32 patients who presented with chronic pancreatitis and mass lesion to the Department of Surgical Gastroenterology, Government Stanley Hospital, Chennai were included for the study. Among these 10 were due to Alcoholic pancreatitis and 22 were due to Tropical calcific pancreatitis (TCP). Alcoholic chronic pancreatitis was defined as chronic pancreatitis associated with the consumption of greater than 50 units of alcohol per week for atleast 5 years. TCP was defined as non-alcoholic pancreatitis with features of younger age at onset, presence of large intraductal calculi, an accelerated course of the disease leading to the end points of diabetes and/or steatorrhoea.Detailed history was obtained from all patients. CONCLUSION : In the appropriate clinical setting, a patient with sudden worsening of abdominal pain with S.Bilirubin > 6.5 mg%, CA 19-9>114 U/ml, MPD>13.5 mm, CBD>16 mm & multiple Intrapancreatic cystic lesions should be strongly considered to have malignancy

The effect of cigarette smoke exposure on the development of inflammation in lungs, gut and joints of TNFΔARE mice

The inflammatory cytokine TNF-alpha is a central mediator in many immune-mediated diseases, such as Crohn's disease (CD), spondyloarthritis (SpA) and chronic obstructive pulmonary disease (COPD). Epidemiologic studies have shown that cigarette smoking (CS) is a prominent common risk factor in these TNF-dependent diseases. We exposed TNF Delta ARE mice; in which a systemic TNF-alpha overexpression leads to the development of inflammation; to 2 or 4 weeks of air or CS. We investigated the effect of deregulated TNF expression on CS-induced pulmonary inflammation and the effect of CS exposure on the initiation and progression of gut and joint inflammation. Upon 2 weeks of CS exposure, inflammation in lungs of TNF Delta ARE mice was significantly aggravated. However, upon 4 weeks of CS-exposure, this aggravation was no longer observed. TNF Delta ARE mice have no increases in CD4+ and CD8+ T cells and a diminished neutrophil response in the lungs after 4 weeks of CS exposure. In the gut and joints of TNF Delta ARE mice, 2 or 4 weeks of CS exposure did not modulate the development of inflammation. In conclusion, CS exposure does not modulate gut and joint inflammation in TNF Delta ARE mice. The lung responses towards CS in TNF Delta ARE mice however depend on the duration of CS exposure

Optical and structural analysis of solar selective absorbing coatings based on AlSiOx:W cermets

It is reported in this work the development and study of the optical and structural properties of a solar selective absorber cermet based on AlSiOx:W. A four-layer composite film structure, W/AlSiOx:W(HA)/AlSiOx:W(LA)/AlSiOx, was deposited on stainless steel substrates using the magnetron sputtering deposition method. Numerical calculations were performed to simulate the spectral properties of multilayer stacks with varying metal volume fraction cermets and film thickness. The chemical analysis was performed using X-ray photoelectron spectroscopy and the results show that in the high metal volume fraction cermet layer, AlSiOx:W(HA), about one third of W atoms are in the W-O oxidation state, another third in the Wx+ oxidation state and the last third in the W4+, W5+ and W6+ oxidation states. The X-ray diffractograms of AlSiOx:W layers show a broad peak indicating that both, W and AlSiOx, are amorphous. These results indicate that this film structure has a good spectral selective property that is suitable for solar thermal applications, with the coatings exhibiting a solar absorptance of 94-95.5% and emissivities of 8-9% (at 100 degrees C) and 10-14% (at 400 degrees C). The samples were subjected to a thermal annealing at 450 degrees C, in air, and 580 degrees C, in vacuum and showed very good oxidation resistance and thermal stability. Morphological characterizations were carried out using scanning electron microscopy and atomic force microscopy. Rutherford Backscattering experiments were also performed to analyze the tungsten depth profile.The authors acknowledge the support of the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. The authors are also grateful to the financial support of FCT, POCI and PORL operational programs through the project POCI-01-0145-FEDER-016907 (PTDC/CTM-ENE/2882/2014), co-financed by European community fund FEDER. The authors also acknowledge GIST Japan for using the XPS-Kratos.info:eu-repo/semantics/publishedVersio

Impact assessment of water efficient rice production technology on farmers’ field

The experiments were conducted during kharif season of 2018 and 2019 at farmers’ fields, Madurai in the Southern Zone of Tamil Nadu to find out the water efficient rice production technology. The experiment consisted of six crop establishment treatments viz., direct planting system, drum seeding, system of rice intensification (SRI), aerobic rice, drip irrigated rice and conventional planting system. The rice variety ASD 16 was used and the experiments were arranged in a randomized block design with four replications. Among the water efficient techniques, drum seeding registered the higher grain yield (5650 kg ha-1), which was comparable to the direct planting system (5592 kg ha-1). The system of rice intensification produced the grain yield of 5025 kg ha-1. The conventional method of transplanting produced higher yield than SRI. Interestingly, the water productivity was higher in aerobic rice (6.92 kg/ ha mm-1 of water) despite its lower yield. Around 49.6 % water can be saved by means of aerobic rice when compared to conventional method of rice cultivation. Hence, the water efficient methods like drum seeding and direct planting systems are recommended for canal irrigated areas, while aerobic rice is suitable for water scarcity regions, turn irrigation systems and well irrigated areas to enhance water use efficiency and sustain rice farming