A study on hydrogen storage by use of cryoadsorbents

This paper reports investigations on the techniques and economics of hydrogen storage by means of cryoadsorption. Also a comparison with alternative storage methods is included. The hydrogen storage capacity of several adsorbents in the temperature range 65–150 K has been investigated experimentally. Based on these data, economics and operating conditions for minimum total costs of the system are calculated. Utilization-factor and capacity-factor parameters are shown to be decisive for outlining the favourable ranges of application for competitive hydrogen storage methods.     

Reaction of zirconium fluoride glass with water: kinetics of dissolution

When liquid water contacts a zirconium-barium-lanthanum fluoride glass, at least three different processes occur. Barium and zirconium fluoride dissolve into the water, water penetrates into the glass, and zirconium fluoride crystals grow on the glass surface, in static solution. The rate of dissolution, as measured by solution analysis, is possibly controlled by diffusion in the solid surface; surface blockage and surface reactions are other possible kinetic steps involved. Diffusion in solution is not the controlling mechanism. Hydrogen profiles in the glass surface suggest that the penetration rate of water into the glass is controlled by diffusion and a surface reaction.     

Evolution of an instinct under long-term divergent selection for geotaxis in domesticated populations of Drosophila melanogaster..

Describes long-term divergent selection for geotaxis in lines of the fruit fly. After 26 yrs (600+ generations) of intermittent selection, the initial experimental procedure showed that the mean geotactic scores remained stable on relaxed selection, a result suggesting that evolutionary changes had occurred in these lines. Because the stability was not due to genetic fixation (homozygosity) of the lines, it is concluded that it was due to either (a) close linkage of genes associated with geotaxis (which would not result in enduring change) or (b) the development of new coadapted gene complexes utilizing genes associated with extreme geotaxis expression (which should result in enduring change). Better evidence for the latter hypothesis was obtained, during the 2nd experimental procedure, from the low- than the high-geotaxis line. The notions of coadaptation and genetic homeostasis are considered, as well as the prospective use of the geotaxis lines to study such concepts experimentally. The geotactic behavior expressed in each line is defined as instinctive: It increases reproductive success and is characteristic of a population. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Computer aided design and new manufacturing methods for electronic materials

The world-wide sales for silicon integrated circuits totalled some £3,500M in 1980. The high growth rate of the industry is generated by high levels of investment in research, development and capital equipment leading to rapid innovation in design and manufacturing methods. This article concentrates on the increasing use of computers in the design process, new design concepts and the efforts to make the components within the silicon chip even smaller.     

Optimum design of steel frames with stability constraints

Optimum design algorithms based on the optimality criteria approach are proven to be efficient and general. They have the flexibility of accomodating variety of design constraints such as displacement, stress, stability and frequency in the design problem. The design methods developed recently, although considering one or more of these constraints, lack the necessity of referring to any relevant design code. The algorithm presented for the optimum design of street frames implements the displacement and combined stress limitations according to AISC. The recursive relationship for design variables in the case of dominant displacement constraints is obtained by the optimality criteria approach. The combined stress inequalities which include in-plane and lateral buckling of members are reduced into nonlinear equations of design variables. The solution of these equations gives the values of bounds for the variables in the case where the stress constraints are dominant in the design problem. The use of effective length in the combined stress constraints makes it possible to study the effect of the end rigidities on the final designs. The design procedure is simple and easy to program which makes it particularly suitable for microcomputers. A number of design examples are considered to demonstrate the practical applicability of the method. It is also shown that the design procedure can be employed in selecting the optimum topology of steel frames.     

The concept of an endurance limit for adhesive joints

The effect of cyclic stressing on the strength of single lap adhesive joints has been studied and a considerable reduction in strength observed when the maximum stress exceeds about 40% of the ultimate tensile strength, but whether or not a true endurance limit exists is not proven. Fallacies are shown in some of the techniques which have been proposed for studying the fatigue behaviour of adhesive joints.     

Optimal size,hydraulic retention time and volatile solids loading rate of biogas unit using water hyacinth

With a view to evaluate the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth, experiments were conducted in a 160 dm³ capacity, well-mixed continuous digestion unit at ambient temperature. The optimal design of biogas plant using water hyacinth was elucidated, to provide a unit giving a maximum methane yield of 0.16 nm³ kg^?1 volatile solids added, which was 60% greater than the conventional plant using cowdung. The calculations of optimal design factors were based on reactor size, hydraulic retention time and volatile solids loading rate; considerations were made of capital cost, running costs and operational revenue.     

Learning vector quantization for the probabilistic neural network

A modified version of the PNN (probabilistic neural network) learning phase which allows a considerable simplification of network structure by including a vector quantization of learning data is proposed. It can be useful if large training sets are available. The procedure has been successfully tested in two synthetic data experiments. The proposed network has been shown to improve the classification performance of the LVQ (learning vector quantization) procedure.     

A compositional approach to multiparadigm programming

The author points out that although different aspects of a system require different approaches, programmers are confined to their language's one paradigm. Multiparadigm programming makes it possible to match the paradigm to the problem. The potential of paradigm composition as an approach to multiparadigm programming is explored. In paradigm composition, a multiparadigm program is written as a collection of single-paradigm programs. The single-paradigm programs are composed, which means that they execute concurrently and cooperatively to form the whole of a functioning system. Interactions between paradigms are defined at the conceptual levels of the participating paradigms. The case of a small prototype telephone network is considered as an example of paradigm composition.<>     

Dynamic programming for 2-D discrete linear systems

The authors calculate the optimal control of 2-D discrete linear systems using a dynamic programming method. It is assumed that the system is described with Roesser's state-space equations for which a 2-D sequence of inputs minimizing the given performance criterion is calculated. The method is particularly suitable for problems with bounded states and controls, although it can also be applied for unbounded cases. One numerical example is given