An inverse model to determine the heat transfer coefficient and its evolution with time during solidification of light alloys

Infra-red probes linked to pyrometric chains and thermocouple arrays have been used to accurately determine both casting and die surface temperatures during the solidification of an aluminium A380 alloy and the magnesium alloy AZ91D. An inverse model was then used to accurately determine the heat flux densities and interfacial heat transfer coefficients and the rapid evolution of these values with time during high pressure die casting of these alloys

A 6.7 KBPS vector sum excited linear prediction on TMS320C54X digital signal processor

In this paper, a 6.7-kbps vector sum excited linear prediction (VSELP) coder with less computational complexity is presented. A very efficient VSELP codebook with nine basis vectors and a heuristic K-selection method (to reduce the search space and complexity) is constructed to obtain the stochastic codebook vector. The nine basis vectors are obtained by optimizing a set of randomly generated basis vectors. During the optimization process, we have trained the basis vectors to give the system apriori knowledge of the characteristics of the input. The coder is implemented on a TMS320C541 digital signal processor. The performance is evaluated by testing the 6.7-kbps VSELP coder with different test speech data taken from different speakers. The quality of the coder is estimated by comparing the performance of the 6.7-kbps VSELP coder with an 8-kbps VSELP speech coder based on the IS-54 standards

Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography

High-temperature two-dimensional liquid chromatography (HT 2D-LC) using HT-HPLC as first dimension and HT-SEC as second dimension holds enormous potential to investigate the distribution according to molar mass and chemical composition of bimodal high density polyethylene (BiHDPE), as it avoids drawbacks of crystallization-based techniques. In this study, we have stepwise optimized the chromatographic parameters of 1D, comprising gradient slope and temperature, using model homo- and copolymers of ethylene with the aim to minimize the impact of molar mass on the compositional separation. Then the HT-HPLC was hyphenated to HT-SEC and optimum conditions for the volume of the sample transfer loop were probed with regard to the resolution of BiHDPE into the individual constituents HDPE and LLDPE. A particular important aspect was the use of infrared (IR) detection, and the demands it puts on the chromatographic aspects: We have shown that IR detection can be successfully applied in HT 2D-LC of BiHDPE, which is broadly distributed with regard to short chain branching and molar mass, only when the separation in 2D is optimized with regard to chromatographic resolution. As final result a bimodality is evident in the contour and the 3D surface plots as well as in both HPLC and SEC projections generated from HT 2D-LC

Private Agricultural Research

This chapter serves to assess the quantity and impact of private agricultural research in developing countries, alongside the policies which affect that research. To provide context, an outline of the history, size and structure of private research presents data on research expenditures by region, by agency, by crop and by industrial sector. Evidence on research inputs reflects not only the importance of private research, but also the wide national and regional differences in both inputs and implementation of programs. Research output and intellectual property rights (IPR) protection are also strikingly different across time and space, as seen in data on agricultural IPRs by region, by industrial origin, and by crop type. The diffusion of agricultural innovations among farmers is described using data on approvals of genetically modified crops, and on cultivated areas actually planted. Studies of the subsequent impacts of agricultural research show that private sector research is making an important contribution to agricultural productivity growth in some countries and could make an even larger impact if government policies were more favorable. The conclusion provides a review of economic and policy determinants affecting private incentives, and some policy prescriptions to encourage further investment.Farmers, Farm Production and Farm Markets

Interfacial heat transfer during die casting of an Al-Si-Cu alloy

The relationship between in-cavity pressure, heat flux, and heat-transfer coefficient during high-pressure die casting of an Al-9 pct Si-3 pct Cu alloy was investigated. Detailed measurements were performed using infrared probes and thermocouple arrays that accurately determine both casting and die surface temperatures during the pressure die casting of an aluminum A380 alloy. Concurrent in-cavity pressure measurements were also performed. These measurements enabled the correlation between in-cavity pressure and accurate heat-transfer coefficients in high-pressure die-casting operations