The effect of large strains on ageing of a filled elastomer

Strain endurance experiments on a filled elastomer were performed at several temperatures. It was found that superimposed prestraining accelerated the ageing process. This process was caused by microstructural changes in the elastomer. In order to evaluate the mechanical properties of a filled elastomer it is necessary to take into consideration not only the ageing effects but also the loading history.     

High-temperature electrical conductivity of aluminium nitride

The electrical conductivity of hot-pressed polycrystalline aluminium nitride doped with oxygen and beryllium was measured as a function of temperature from 800 to 1200° C and over a range of nitrogen partial pressure from 10² to 10⁵ Pa. The effect of beryllium dopant, the independence of conductivity from nitrogen partial pressure, and the observed activation energy suggested extrinsic electronic species or aluminium vacancies as charge carriers. Polarization measurements made with one electrode blocking to ionic species indicated that the aluminium nitride with oxygen impurity was an extrinsic electronic conductor.     

Nonlinear load-deflection relation of toroidal shells subjected to axisymmetric compression between rigid plates

Utility of toroidal shells as shock absorbers for radioactive materials' shipping casks is discussed by carrying out numerical and experimental analyses. The static load-deflection relations under axisymmetric compression between rigid plates are presented.A simple elastic-plastic analytical method is first developed on the basis of an incremental Rayleigh-Ritz method by taking account of the large deflections and the continuous change of contact points. Meridional compression is neglected and the meridional curvature distribution is approximated by a trigonometric series. Strain-hardening material properties and axisymmetric deformation are also assumed. In order to provide data for comparison purposes, static compression tests were performed using six models of different shapes and dimensions made of 304-type stainless steel. Finally, the applicability of the numerical method developed in this paper is discussed.The mechanical behavior of toroidal shells is also discussed.     

The automated simulation of dynamic non-linearity to shot-peening mechanics

This paper gives an automated simulation of dynamic non-linearity to shot-peening mechanics. Three-dimensional constitutive material law expressed in the stress invariants is used along with the nonlinear analysis based on the concept of initial stress. Residual stresses, strains, displacements and plasticity can be calculated using information in Gauss integration points. The ultimate load is reached when the algorithm does not converge. The corresponding failure modes can be interpreted as those for which as state of equilibrium is no longer possible. The final results obtained the shakedown diagrams plotted in three dimensions. The history of these diagrams is self-explanatory.     

Segregation in sputtered Co-Cr films

The segregation growth process in sputtered Co-Cr films is investigated by examining the effect of substrate temperature on the segregated microstructure and magnetic properties. In sputtered Co-25at%Cr films, segregation occurs below 560°C, and both the saturation magnetization and the perpendicular anisotropy constant show a maximum around a substrate temperature of 300°C, where a specific microstructure, called a CP (chrysanthemum-like pattern) structure, is observed. The results suggest that the CP structure becomes observable in the highly segregated state and generates high perpendicular anisotropy. A new segregation growth model is derived from the results of the CP structure observations. Using this model, it is possible to explain the continuous transition of the magnetization mode between the continuous and the particulate modes.     

Modeling of optical low coherence reflectometry recorded Braggreflectograms: evidence to a decisive role of Bragg spectral selectivity

This paper draws attention to the basic principles governing reflections in uniform Bragg reflectors (BR) when measured employing optical low coherence reflectometry (OLCR) technique. Using computations based on transfer matrix method (TMM), we first showed a strong spectral dependence of Bragg reflectograms on an OLCR probe spectrum. Later, this dependence is exploited to evaluate, for the first time, the coupling coefficient κ of a Bragg grating in a distributed Bragg reflector (DBR) laser on InP     

On rigorous transaction scheduling

The class of transaction scheduling mechanisms in which the transaction serialization order can be determined by controlling their commitment order, is defined. This class of transaction management mechanisms is important, because it simplifies transaction management in a multidatabase system environment. The notion of analogous execution and serialization orders of transactions is defined and the concept of strongly recoverable and rigorous execution schedules is introduced. It is then proven that rigorous schedulers always produce analogous execution and serialization orders. It is shown that the systems using the rigorous scheduling can be naturally incorporated in hierarchical transaction management mechanisms. It is proven that several previously proposed multidatabase transaction management mechanisms guarantee global serializability only if all participating databases systems produce rigorous schedules     

Some studies on plasma polymerization of benzene and cyclohexane in the gas phase

The glow discharge polymerization benzene and cyclohexane at 13.56 mHz, and 60 watts, in a plug flow reactor with inner electrodes was studied. Film powder and oily polymeric products were obtained from benzene, and only films were produced from cyclohexane. Polymers produced were analyzed by infrared and their characteristic maps demonstrating the correlation between various physical forms of polymer and reaction conditions were prepared. Excepting oily products, all others are found highly crosslinked and contained free radicals. Contrary to the plasma polymerization (PP) oil of benzene, all others showed no aromatic character.     

Useful solar heat gains in multi-zone non-domestic buildings as a function of orientation and thermal time constant

Two parameters affecting useful solar absorption are orientation and thermal mass. Solar energy absorption in buildings depends on these parameters in a complex manner particularly when considering large glazing ratios and large direct components of insolation. Therefore, where parameters of different zones in a multi-zone building vary, useful solar absorption will also vary. For higher northern latitudes, compared with south orientation, useful solar absorption differs by about 2%, 4% and 6% between large and small time constants for east, west and north orientations, respectively. The smallest and largest differences are for east and north orientations, respectively. Fenestration design should be a consequence of orientation and overshading, seeking to balance daylight, solar gains and heat losses.     

A Multilayer Peer-to-Peer Framework for Distributed Synchronous Collaboration

Although interest in Web-based multiuser interaction is growing, classical server-based multiuser systems are becoming saturated. Consequently, the peer-to-peer (P2P) paradigm is receiving significant attention as an alternative. The authors propose a multilayer P2P framework for developing distributed synchronous collaborative systems using asynchronous P2P platforms. They've used the framework to develop a shared Web browser using the Java programming language and the JXTA platform