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61.
Using ab initio calculations, we find high stability of octahedral Mo6S8 clusters, which can further be condensed to form Mo3nS3n+2 (n, an integer) nanowires. These linear structures are energetically more favorable compared with other closed-packed polyhedral isomers of Mo-S clusters. The octahedral units in nanowires are stabilized by strong Mo-Mo interactions and p-d hybridization between Mo 4d and S 2p orbitals. There is a free electron-like band that crosses the Fermi energy in infinite nanowires and leads to their metallic character. Iodine doping acts as electron donor and can be used to tailor the electronic conductivity. For Mo12S8I4 nanowires, both electrons and holes are found to contribute to conduction. These nanowires are energetically more favorable than the experimentally obtained Mo12S6I12 nanowires. 相似文献
62.
Sadu Venkatesu Rajesh Saxena S. Murugan S. Venugopal 《Transactions of the Indian Institute of Metals》2018,71(3):555-566
The main intent of this work is to develop an instrumented capsule for online determination of uniaxial creep behavior of SS 316L structural specimen. The irradiation capsule has three different zones located one over the other. In the bottom zone of the capsule, the specimen is located, with one end fixed to the bottom portion of capsule and the other end connected to a central tube through a connecting plug. In the top zone a linear variable differential transducer (LVDT) is placed and its core is passed through the central tube. The end point of the LVDT core touches the plug connected to the specimen to measure the elongation of the structural specimen. In this capsule setup, bellows are used to apply a load on the structural specimen with the use of pressurized argon gas. With the application of pressure, the bottom bellow will expand and the top bellow will get compressed. During this expansion of the bottom bellow, tensile load will be applied on the specimen, and the elongation of the structural specimen will be measured by the movement of the core of the LVDT. This paper discusses the details of the design, assembly of an out-of-pile version of instrumented capsule and its experimental results are compared with literature results. The creep experiments have been carried out at three different temperatures and three different stresses (269 MPa at 450 °C, 287 MPa at 500 °C and 306 MPa at 550 °C). Initially the capsule is filled with pre-pressurized argon gas at 6 MPa at room temperature. We have observed that the force/load due to argon gas pressure is the major component for the tensile loading of the specimen and 95% of the total load acts on the SS 316L specimen and remaining 5% load only acts on the bellow. Design concept of instrumented capsule for uniaxial creep measurement has been validated. 相似文献
63.
Application of NSGA-II Algorithm to Single-Objective Transmission Constrained Generation Expansion Planning 总被引:2,自引:0,他引:2
This paper presents an application of elitist nondominated sorting genetic algorithm version II (NSGA-II), a multiobjective algorithm to a constrained single objective optimization problem, the transmission constrained generation expansion planning (TC-GEP) problem. The TC-GEP problem is a large scale and challenging problem for the decision makers (to decide upon site, capacity, type of fuel, etc.) as there exist a large number of combinations. Normally the TC-GEP problem has an objective and a set of constraints. To use NSGA-II, the problem is treated as a two-objective problem. The first objective is the minimization of cost and the second objective is to minimize the sum of normalized soft constraints violation. The hard constraints (must satisfy constraints) are treated as constraints only. To improve the performance of the NSGA-II, two modifications are proposed. In problem formulation the modification is virtual mapping procedure (VMP), and in NSGA-II algorithm, controlled elitism is introduced. The NSGA-II is applied to solve TC-GEP problem for modified IEEE 30-bus test system for a planning horizon of six years. The results obtained by NSGA-II are compared and validated against single-objective genetic algorithm and dynamic programming. The effectiveness of each proposed approach has also been discussed in detail. 相似文献
64.
65.
Ki Hyun Kim Yasutoshi IriyamaKazuo Yamamoto Shota KumazakiToru Asaka Kinuka TanabeCraig A.J. Fisher Tsukasa HirayamaRamaswamy Murugan Zempachi Ogumi 《Journal of power sources》2011,196(2):764-767
The interfacial layer formed between a lithium-ion conducting solid electrolyte, Li7La3Zr2O12 (LLZ), and LiCoO2 during thin film deposition was characterized using a combination of microscopy and electrochemical measurement techniques. Cyclic voltammetry confirmed that lithium extraction occurs across the interface on the first cycle, although the nonsymmetrical redox peaks indicate poor electrochemical performance. Using analytical transmission electron microscopy, the reaction layer (∼50 nm) was analyzed. Energy dispersive X-ray spectroscopy revealed that the concentrations of some of the elements (Co, La, and Zr) varied gradually across the layer. Nano-beam electron diffraction of this layer revealed that the layer contained neither LiCoO2 nor LLZ, but some spots corresponded to the crystal structure of La2CoO4. It was also demonstrated that reaction phases due to mutual diffusion are easily formed between LLZ and LiCoO2 at the interface. The reaction layer formed during high temperature processing is likely one of the major reasons for the poor lithium insertion/extraction at LLZ/LiCoO2 interfaces. 相似文献
66.
G. Murugan K. Raghukandan U. T. S. Pillai B. C. Pai K. Mahadevan 《Transactions of the Indian Institute of Metals》2010,63(2-3):511-514
Magnesium is the lightest structural material used and it is important to explore its properties completely as it is used in aviation, automotive, communication etc., This paper reports the reliability analysis carried out on the high cycle fatigue investigations performed on cast AZ91 Magnesium alloys under transverse load. An Electro dynamic shaker system was used to apply transverse load on the specimens fabricated as per ASTM standard. Weibull analysis was under taken to check and compare the reliability of the investigations on gravity cast and low pressure cast AZ91 magnesium alloys. 相似文献
67.
68.
M. Manikandan N. Arivazhagan M. Arivarasu K. Mageshkumar Deva N. Rajan B. Arul Murugan P. Prasanth S. Sukumar R. Vimalanathan 《Transactions of the Indian Institute of Metals》2017,70(3):661-669
The present work investigates the microstructure and mechanical properties of alloy C-276 fabricated by continuous and pulsed current gas tungsten arc welding process and by employing ER2553 filler wire. Optical and scanning electron microscopic analyses were carried out to study the microstructures of weldments produced. Energy dispersive X-ray spectroscopy (EDS) was performed to investigate the formation of secondary phases in the weldments. The results disclosed that pulsed current gas tungsten arc welding showed refined microstructure compared to continuous current gas tungsten arc welding. SEM/EDS analysis revealed the segregation of Mo in the weld interface regions in both the welding techniques. The extent of microsegregation reduced the strength and toughness of the weld joint compared to the base metal. Bend test revealed cracks in the weld interface region in both the weldments. 相似文献
69.
Monitoring of hard turning using acoustic emission signal 总被引:1,自引:0,他引:1
Bhaskaran J. Murugan M. Balashanmugam N. Chellamalai M. 《Journal of Mechanical Science and Technology》2012,26(2):609-615
Monitoring of tool wear during hard turning is essential. Many investigators have analyzed the acoustic emission (AE) signals
generated during machining to understand the metal cutting process and for monitoring tool wear and failure. In the current
study on hard turning, the skew and kurtosis parameters of the root mean square values of AE signal (AERMS) are used to monitor
tool wear. The rubbing between the tool and the workpiece increases as the tool wear crosses a threshold, thereby shifting
the mass of AERMS distribution to right, leading to a negative skew. The increased rubbing also led to a high kurtosis value
in the AERMS distribution curve. 相似文献
70.
Pyrolysis kinetics of thermal decomposition of bitumen was investigated by thermogravimetric analysis (TGA). TGA experiments were conducted at multiple heating rates of 5, 10, 20°C min–1 up to 800°C to obtain the pyrolysis characteristics of bitumen. Weight loss curve from TGA shows that two different stages occurred during bitumen pyrolysis. Differential method has been used for determining the kinetic parameters and the best fit for the order of reaction was found based on the R2 values. Kinetics results confirm the presence of two different stages in bitumen pyrolysis with varying kinetic parameters. The average activation energy for the first and second stage was 29 and 60 kJ mol?1 and the average order of the reaction was 1.5 and 0.25, respectively. Experiments have been conducted with different reservoir sand. The effect of different source of sand reveals no effect on the pyrolysis behaviour of bitumen. A considerable difference was found with the pyrolysis of bitumen–sand mixtures and bitumen alone based on coke yield and activation energy. © 2011 Canadian Society for Chemical Engineering 相似文献