Pressure-induced band cross-over in Pb1−x Sn x Te

Resistivity and thermoelectric power studies have been carried out on two semiconductor alloy systems viz Pb_0·8Sn_0·2Te and Pb_0·6Sn_0·4Te up to 35 kbar pressure. Thermoelectric power and resistivity data on Pb_0·8Sn_0·2Te indicate that the energy gapE _g=E _{L −} ⁶ −E _{L 6} ⁺ decreases with pressure resulting in a zero gap state near 35 kbar pressure. TEP studies on the alloy system Pb_0·6Sn_0·4Te provide direct evidence for a pressure induced L ₆ ⁻ →L ₆ ⁺ cross over transition.     

A methodology for evaluating computer integrated manufacturing technologies

The decision to invest in advanced manufacturing technology is often made at the strategic level. The technique to be used to justify these decisions should have the ability to incorporate the non-quantifiable, intangible benefits associated with implementing these technologies. Among the methods introduced recently, the linear additive models have received considerable attention. This paper reviews a linear additive method which can be used to evaluate long-term and short-term automation manufacturing investment alternatives. The paper also concentrates on those cases in which some common characteristics of available alternatives are assumed to be independent.     

Near surface stress analysis strategies for axisymmetric fretting

Fretting is essentially a surface phenomenon, but bulk stresses and material properties contribute to subsequent failure. This feature of fretting demands a thorough understanding of near surface stresses under the joint action of normal, shear and thermal loading. Axisymmetric fretting is of great concern in piping and coupling design. In this paper, we develop design tools for Near Surface Analysis (NSA) for understanding axisymmetric fretting. Axisymmetric Fretting Analysis (AFA) becomes formidable owing to localised tractions that call for Fourier transform techniques. We develop two different NSA strategies based on two-dimensional plane strain models: 2D strip model (2DS) and half-plane Flamant model (2DF). We compare the results of 2DS and 2DF with the exact results for AFA obtained using Love’s stress function in conjunction with Fourier transform. There is a good correspondence between stress components obtained from 2D-models.     

Chinese-Indian-German Collaboration Results that Provided the Impetus for the Foundation of COLLNET

The collaboration model of Kretschmer was applied to the co-authorshipnetwork of Indian medicine with the aim of being able to observe changes instructure over a period of 30 years. The idea of Liang, on her “Distributionof Major Scientific and Cultural Achievements in Terms of Age” was putin relation to the collaboration model by Kretschmer. This revised version was published online in June 2006 with corrections to the Cover Date.     

A design framework for e-business infrastructure integration andresource management

One of the challenges faced by an enterprise with employees in multiple locations is to design a high performance, secure and interoperable distributed computing system (DCS) to interconnect all locations and operations. The problem is computationally hard; hence, subcomponents of it have been studied in detail. These tend to be complex, predominantly theoretical, and somewhat limited from a practical standpoint in terms of providing an integrated solution. Researchers have indicated the need to study the integrated DCS design problem. We merge the complex components and demonstrate that this intrinsically hard problem can be modeled using a component-wise iterative approach. We present a methodology for resource planning and integration that is simple and practical, and can be applied to real-life problems. The methodology includes performance, cost, security and interoperability issues as DCS design objectives. It distributes data and application systems across multiple locations, and aids in security and interoperability configuration, such that the overall design objectives are satisfied. This is one of the first attempts at combining the various components of DCS design and applying it to a real-life problem. The design framework has been successfully used to design a distributed training system for a large, geographically dispersed organization     

Pressure induced order-disorder transition in a diblock copolymer

Polymers are known to undergo order↔order and order↔disorder transitions, when subjected to a change of pressure, temperature, solvent, pH of the medium etc. The molecular processes, which alter the volume of the system, are found to be highly sensitive to the pressure. In the present communication Zimm and Bragg model of helix↔coil transition has been modified to interpret the experimental data of pressure induced phase transition in polystyrene-polybutadiene [PS-PB] at different pressurization rates, as reported by Migler and Han, utilizing the Birefringence and small angle neutron scattering technique. An expression for the degree of order is obtained from the grand partition function for the entire chain in terms of nucleation parameter, which controls the transition width. The nucleation parameter σ increases with the increase in the ODT temperatures of the system. The phenomenon of hysteresis has been discussed in relation to the pressurization rate, which increases/decreases with the corresponding increase/decrease in the pressurization rate. The theoretical transition curves are found to be in good agreement with experimental data.     

Static hole in a two-dimensional antiferromagnet

The energetics of static hole in a 2D antiferromagnetic (AF) is studied. AF is described by magnon operators in the LSW approximation, while the holes by fermionic operators. The energy spectrum of the magnons in the presence of the hole is determined from the perturbed Green’s function.     

Microgrinding of deep micro grooves with high table reversal speed

Recent progress in the miniaturization of electronic items introduces manufacturing challenges for achieving both better surface integrity and high throughput. Controlled thermal interaction processes physically vaporize the material for producing the miniature components but the poor surface and sub-surface characteristics introduce a niche for thermo-mechanical processes, particularly microgrinding. Prior microgrinding attempts have focussed on axi-symmetrical components of hard-brittle materials. For non-axi-symmetrical, high-aspect ratio miniature components, edge chipping was encountered. This paper reports a new grinding method that uses “high table reversal speeds” for reducing the “grit cut load” and hence facilitates the microgrinding process. An arrangement that functions on the principles of four bar linkage with a sliding and rotating pair was devised. This arrangement was designed to reciprocate between 300–1000 strokes/min for a stroke length of 10–70 mm. As a result the table feed rate range was increased from the conventional 300–20 000 mm/min to 5000–55 000 mm/min.Process characterization of the new grinding method was observed for hard-brittle materials. A physical model was developed which links the process parameters with appropriate boundary conditions and the model was verified experimentally. The experimental model was used to explain the mechanism of grinding while employing high table reversal speeds. Process characterization includes grinding force, grinding-ratio, grinding wheel topography, surface finish and SEM study. Also, the process was applied to produce mold-insert which in turn was used for molding the micro-mechanical cantilever sensor parts. Deep slots of size: 1.2×0.1×1.5 mm with an aspect ratio of 15 was successfully produced with this method. The new grinding device and method promote microgrinding through integration to an existing grinder and therefore reduces the additional cost on the capital resources.