Activation energies for the deformation of superplastic alloys and their phases derived from hot microhardness studies

Activation energies for two superplastic alloys (Zn78-AI22 and Cu60-Zn4O) and their individual phases have been determined by plottingH/E againstT _m/T and utilizing the relationshipH/E = G exp (Q/nRT). Hot hardness measurements were made with a microhardness tester and Young's modulus values were obtained over the appropriate temperature range using the Rayleigh vibration technique. The activation energies obtained are compared, wherever possible, with those reported in the literature and are found to be in reasonably good agreement. These data help in the understanding of the mechanisms of superplasticity in these alloys.     

Local buckling and inelastic cyclic behavior of tubular sections

Moment-curvature relationship of a circular tubular section under reversed loading conditions is obtained. A simple kinematic model, proposed previously by the authors, is used here to obtain the local buckling branch of the moment-curvature relationship. Three types of closed form expressions are proposed to approximate the reversed loading branch of the computed moment-curvature curve of the locally buckled section. These expressions can be used to obtain the load-deflection relationship of a long circular tubular member/brace.     

Transaction attributes and buyer-supplier relationships in AMT acquisition and implementation: the case of Malaysia

This paper explores how transaction attributes of technology affect differences in the relationship between technology buyers and suppliers. It also examines the impact on performance of different patterns of relationship between technology buyers and suppliers. Data obtained from 147 manufacturing firms in Malaysia are used to test several hypotheses, which were derived from a review of the literature on technology, transaction cost theory and buyer–supplier relationships (BSR). The research results indicate that the higher the level of technological complexity, specificity and uncertainty, the more firms are likely to engage in a closer relationship with technology suppliers. Even though the majority of firms reported improvements in their performance, results indicate that firms demonstrating a closer relationship with technology suppliers are more likely to achieve higher levels of performance than those that do not. It is also shown that with high levels of transaction attribute, implementation performance suffers more when firms have weak relationships with technology suppliers than with moderate and low levels of transaction attribute.     

Mitochondrial adenine nucleotide translocase is modified oxidatively during aging

The purpose of this study was to test the hypothesis that elevation in protein oxidative damage during the aging process is a targeted rather than a stochastic phenomenon. Oxidative damage to proteins in mitochondrial membranes in the flight muscles of the housefly, manifested as carbonyl modifications, was detected immunochemically with anti-dinitrophenyl antibodies. Adenine nucleotide translocase (ANT) was found to be the only protein in the mitochondrial membranes exhibiting a detectable age-associated increase in carbonyls. The age-related elevation in ANT carbonyl content was correlated with a corresponding loss in its functional activity. Senescent flies that had lost the ability to fly exhibited a relatively higher degree of ANT oxidation and a greater loss of functional activity than their cohorts of the same age that were still able to fly. Exposure of flies to 100% oxygen resulted in an increase in the level of ANT carbonyl content and a loss in its activity. In vitro treatment of mitochondria with a system that generated hydroxyl free radicals caused an increase in ANT carbonyl level and a decrease in ANT exchange activity. ANT was also the only mitochondrial membrane protein exhibiting adducts of the lipid peroxidation product 4-hydroxynonenal. Results of this study indicate that proteins in mitochondrial membranes are modified selectively during aging.     

DNA oxidative damage and life expectancy in houseflies

The objective of this study was to explore the relationship between oxidative molecular damage and the aging process by determining whether such damage is associated with the rate of aging, using the adult housefly as the experimental organism. Because the somatic tissues in the housefly consist of long-lived postmitotic cells, it provides an excellent model system for studying cumulative age-related cellular alterations. Rate of aging in the housefly was manipulated by varying the rate of metabolism (physical activity). The concentration of 8-hydroxydeoxyguanosine (80HdG) was used as an indicator of DNA oxidation. Exposure of live flies to x-rays and hyperoxia elevated the level of 8OHdG. The level of 8OHdG in mitochondrial as well as total DNA increased with the age of flies. Mitochondrial DNA was 3 times more susceptible to age-related oxidative damage than nuclear DNA. A decrease in the level of physical activity of the flies was found to prolong the life-span and corresponding reduce the level of 8OHdG in both mitochondrial and total DNA. Under all conditions examined, mitochondrial DNA exhibited a higher level of oxidative damage than total DNA. The 8OHdG levels were found to be inversely associated with the life expectancy of houseflies. The pattern of age-associated accrural of 8OHdG was virtually identical to that of protein carbonyl content. Altoghether, results of this study support the hypothesis that oxidative molecular damage is a causal factor in senescence.     

Transmission of Audio over LTE Packet Based Wireless Networks Using Wavelets

Wireless Personal Communications - One of the recent trends of networking and mobile technology is mobile cloud computing (MCC) that provides rich computational, storage resources and services in...     

Enhancing Coverage Using Weight Based Clustering in Wireless Sensor Networks

Energy conservation in wireless sensor networks (WSNs) is a fundamental issue. For certain surveillance applications in WSN, coverage lifetime is an important issue and this is related to energy consumption significantly. In order to handle these two interlinked aspects in WSN, a new scheme named Weight based Coverage Enhancing Protocol (WCEP) has been introduced. The WCEP aims to obtain longer full coverage and better network life time. The WCEP is based on assigning different weight values to certain governing parameters which are residual energy, overlapping degree, node density and degree of sensor node. These governing parameters affect the energy and coverage aspects predominantly. Further, these four different parameters are prime elements in cluster formation process and node scheduling mechanisms. The weight values help in selection of an optimal group of Cluster Heads and Cluster Members, which result in enhancement of complete coverage lifetime. The simulation results indicate that WCEP performs better in terms of energy consumption also. The enhancement of value 24% in full coverage lifetime has been obtained as compared to established existing techniques.

     

Large bending of pipes

The computer model developed has been used successfully for studying the large pipe-bending problem frequently encountered in offshore structural engineering. The pipe-soil interaction is modelled by using the Coulomb friction law. The modified finite element approach coupled with a modified tangent stiffness procedure is used to handle the nonlinearities (geometric and material, etc.) in the problem. The material nonlinearity has been considered both by the plastic-hinge method and by an elastic-plastic method. Before studying the practical problems, sufficient check problems were analysed and a good agreement was found between theoretically exact solutions and the results obtained from the developed computer model.     

Adoption framework for advanced manufacturing technologies

The paper examines the adoption of advanced manufacturing technology (AMT). The general proposition is that the adoption of AMT reflects an interactive learning process, which is described by the extant use of AMT, firm-specific AMT knowledge accumulation, and the transfer of AMT ideas among networks of firms, suppliers, industry associations and government. This general proposition was specified as a structural equation model of Adoption of AMT. Data were based on the experiences of 224 Australian manufacturing companies that have invested and succeeded in using AMT. The results suggest that the adoption of AMT is primarily a function of a firm's assets for AMT, which comprise the resources, capabilities, and competences for developing and using AMT. The relationship between the adoption of AMT and assets for AMT was reciprocal, which implied a process of dynamic accumulation of both technology and human assets — a view consonant with the competence perspective of the firm. Overall, assets for AMT represent the AMT knowledge base of firms, and were shown to have a crucial role in determining the adoption of AMT.