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排序方式: 共有411条查询结果,搜索用时 31 毫秒
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J. Janaki T. Geetha Kumary Awadhesh Mani E. P. Amaladass N. Radhikesh Raveendran P. Magudapathy S. Kalavathi T. N. Sairam T. R. Ravindran 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2639-2643
The occurrence of superconductivity in iron telluride thin films has been observed upon ageing. The superconducting transition is found to be very robust under an application of magnetic fields up to 10 T. Infrared and Raman spectroscopic characterization of the aged films reveal the formation of Fe1+δTeO x upon ageing. As an alternative method of introducing oxygen in FeTe thin film, oxygen ion irradiation has also been carried out It is found that the irradiated film becomes increasingly disordered and ultimately transforms to an amorphous phase upon increasing the irradiation dose. Investigation of electrical resistivity and optical reflectivity of the irradiated FeTe films indicates an interesting possibility of an ion irradiationinduced phase change memory material in analogy to the phase change characteristics of laserirradiated FeTe films. 相似文献
23.
Silicon - In this paper, electrical and microwave characteristics of Al0.1Ga0.9 N channel HEMTs was reported. The device performance were evaluated for conventional gate, field plate gate,... 相似文献
24.
Influence of High-k Passivation Layer on Gate Field Plate AlGaN/GaN/AlGaN Double Heterojunction HEMT
Silicon - In this work, we have analysed the influence of passivation material such as Silicon dioxide (SiO2), Silicon Nitride (Si3N4), Aluminium oxide (Al2O3), Hafnium Silicon Oxide (HfSiO4),... 相似文献
25.
Silicon - The performance analysis of Ge-Si-VTFETs for analog/RF applications has been studied in this article under various gate dielectric materials. In the proposed device, Ge/Si materials were... 相似文献
26.
It is difficult and challenging to achieve uniform nanoscale surface finish in the contact zone, particularly on freeform (or sculptured) surfaces having different curvatures at different locations. Femoral (or, Knee joint component) is one of such biomedical freeform component which has complex profile along its curvature. Surface conditions of a femoral decide the life of the implant and they play a crucial role in its functionality. The variation in surface roughness of the femoral should be minimum in the contact zone. For this purpose, a special tooling is being proposed for rotational magnetorheological abrasive flow finishing (R-MRAFF) process. A negative replica of the workpiece (knee joint) as a tool (or a fixture) is used so that the medium flow velocity in the fluid flow channel is almost constant (or minimum possible variations) along the medium flow direction. It is able to do differential finishing also along the curvature. In addition, pulsating magnetic field has been used to generate vibrations in the medium in the finishing zone so that the possibility of fresh abrasive particles interacting with the surface of femoral is high. The surface finish has been achieved ranging from 26 nm to 62 nm using the proposed finishing technique and negative replica of the workpiece (femoral) as a fixture. 相似文献
27.
Durwesh Jhodkar M. Amarnath H. Chelladurai J. Ramkumar 《Journal of Mechanical Science and Technology》2018,32(6):2551-2558
This study attributed to post treatment of tungsten carbide (WC) inserts using microwave irradiation. Tungsten carbide inserts were subjected to microwave radiation (2.45 GHz) to enhance its performance in terms of reduction in tool wear rate, cutting force surface roughness and improvement in tool life. Performance of tungsten carbide insert is very much affected by machine operating parameters i.e. speed, feed and depth of cut. An attempt has been made to investigate the effects of machining parameters on microwave treated tool inserts. This paper describes the comparative study of machining performance of untreated and microwave treated WC tool inserts used for turning of AISI 1040 steel. Machining performance has been evaluated in terms of flank wear, cutting force, surface roughness, tool wear mechanisms. Critical examinations of tool wear mechanisms and improvements in metallurgical properties such as microstructural change, phase activation of WC grains were identified using scanning electron microscope (SEM). Results obtained from the turning using the microwave treated tool inserts showed a significant reduction tool wear thereby enhancing the surface quality of workpiece. 相似文献
28.
The spray atomization and combustion characteristics of canola methyl ester (CME) biofuel are compared to those of petroleum based No. 2 diesel fuel in this paper. The spray flame was contained in an optically accessible combustor which was operated at atmospheric pressure with a co-flow of heated air. Fuel was delivered through a swirl-type air-blast atomizer with an injector orifice diameter of 300 μm. A two-component phase Doppler particle analyzer was used to measure the spray droplet size, axial velocity, and radial velocity distributions. Radial and axial distributions of NO, CO, CO2 and O2 concentrations were also obtained. Axial and radial distributions of flame temperature were recorded with a Pt–Pt/13%Rh (type R) thermocouple. The volumetric flow rates of fuel, atomization air and co-flow air were kept constant for both fuels. The droplet Sauter mean diameter (SMD) at the nozzle exit for CME biofuel spray was smaller than that of the No. 2 diesel fuel spray, implying faster vaporization rates for the former. The flame temperature decreased more rapidly for the CME biofuel spray flame than for the No. 2 diesel fuel spray flame in both axial and radial directions. CME biofuel spray flames produced lower in-flame NO and CO peak concentrations than No. 2 diesel fuel spray flames. 相似文献
29.
Multi-objective optimization for optimum tolerance synthesis with process and machine selection using a genetic algorithm 总被引:2,自引:2,他引:0
K. Geetha D. Ravindran M. Siva Kumar M. N. Islam 《The International Journal of Advanced Manufacturing Technology》2013,67(9-12):2439-2457
This paper presents a new approach to the tolerance synthesis of the component parts of assemblies by simultaneously optimizing three manufacturing parameters: manufacturing cost, including tolerance cost and quality loss cost; machining time; and machine overhead/idle time cost. A methodology has been developed using the genetic algorithm technique to solve this multi-objective optimization problem. The effectiveness of the proposed methodology has been demonstrated by solving a wheel mounting assembly problem consisting of five components, two subassemblies, two critical dimensions, two functional tolerances, and eight operations. Significant cost saving can be achieved by employing this methodology. 相似文献
30.
M. Ravi Sankar V.K. Jain J. Ramkumar 《International Journal of Machine Tools and Manufacture》2010,50(7):637-650
The present study focus on abrasive flow finishing (AFF), a process that finishes complex internal and external geometries with the help of viscoelastic abrasive medium, while keeping in mind its low finish and material removal rates (MRR). Researchers have often strived to improve finishing rate and MRR. As an attempt to overcome the said limitations, this paper discusses rotational abrasive flow finishing (R-AFF) process wherein complete tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators. In this study, preliminary experiments are conducted on Al alloy and Al alloy/SiC metal matrix composites (MMCs) at different extrusion pressures, and medium compositions are employed for finding optimum conditions of the same for higher change in roughness (ΔRa). The same optimum conditions are used to study the effect of workpiece rotational speed on (ΔRa), material removal (MR), change in workpiece hardness and surface topology. It is noted that as the workpiece rotational speed increases from 2 to 10 RPM, the experimental helix angle decreases from 22° to 9° and the helical path length increases from 67 to 160 mm. Based on these findings the mechanism of material removal of matrix and reinforcement in MMC using R-AFF have been proposed. Here the matrix material is removed by micro-cutting and three methods of material removal mechanisms for reinforcement are also explained. The scientific logic behind finishing mechanism of matrix and reinforcement, cross hatch patterns, helical path directions, micro-scratch (μ-scratch) width and depth variation with size, orientation and support that active abrasive grain obtains from neighboring abrasives is derived from scanning electron microscopy micrographs. Finally this study establishes that R-AFF can produce 44% better ΔRa and 81.8% more MR compared to the AFF process. Accordingly, R-AFF generates micro cross hatch pattern on the finished surface that can improve lubricant holding capabilities. 相似文献