Production and properties of micro‐porous glas bubble zinc and aluminium composites

Micro‐porous syntactic foams were produced by means of integration of glass bubbles into aluminium and zinc matrices. Preforms of glass bubbles were pressure infiltrated with the alloys AlSi9Cu9 ans ZnAl4Cu using squeeze casting. The preforms were sintered thermically without the use of bonding agents. Using the combination of different sintering steps syntactic foams with locally different densities could be produced. The mechanical properties of the foams were tested indicating a high compression strength of the foams and a very good compression energy absorption. Furthermore, corrosion behaviour and behaviour at higher temperatures were investigated.     

Fast method to compute the scalar product of gradient and given vector

The paper deals with a special problem in Automatic Differentiation. Letf be a rational function ofn variables, let #(f) denote the number of operations to evaluatef(x), letg denote the gradient off. Many algorithms for minimizingf(x) require the scalar productg(u) ^tv. In the standard method for computingg(u) ^tv the amount of work grows withn·#(f). In this note a new method for computingg(u) ^tv is presented. The new method is considerably faster, its amount of work only grows with #(f).     

The possibility of evolving a theory for predicting the service life of reinforced concrete structures

The development in recent years with increasing air pollution, increasing need of energy saving and last not least the growing number of damage in old structures leads to a raising demand to calculate the durability of structures, too. The paper has been prepared by request of the RILEM Technical Committee 45-LTO to show that, in principle, it is possible to evolve a theory for predicting the service life of r.c. structures and to sketch a way how that could be achieved. A lot of necessary basic data can be found scattered in the literature. To collect these data will be the first step to take.     

The relation of acid rain to energy policy

Current energy policies have severely eroded the earth's natural atmospheric waste-receptor capacity. Present acid rain concentrations may require a switch to an alternative energy-resource emphasis. This policy recommendation follows directly from a deductive control theory demonstration which shows that, if fossil-fuel use is continued at present rates, then there is an ever-increasing risk of a man-made environmental crisis of uncertain nature and scope.     

Context and lexical access: Implications of nonword interference for lexical ambiguity resolution.

To eliminate potential "backward" priming effects, S. Glucksberg et al (see record 1986-29080-001) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al is due to postlexical judgments of the congruence of the sentence context and the target, not to context constraining lexical access. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A circuit model for the inductive strip in homogeneous finline

This article describes a circuit model for infinitesimally thin inductive strips centered in homogeneous finline. The model is valid for 0.1 ≤ W/b ≤ 1.0, 0.01 ≤ T/a, and 0.4 ≤ b/a ≤ 0.5 when frequency is in the normal operating band for the rectangular waveguide shield. The error is less than 2.5%.     

CALCE/RAMCAD for Electronics

The University of Maryland's Computer Aided Life Cycle Engineering (CALCE) research effort is aimed at developing techniques for design, analysis, prediction, and optimization of electronics with respect to a variety of design goals. Performance, producibility, reliability, maintainability, life-cycle cost, safety, etc., are the design criteria which are being integrated through the application of interactive heuristic and algorithmic design optimization techniques. The University of Maryland Reliability and Maintainability Computer-Aided Design (RAMCAD) research is CALCE and is focused on second- and third-level electronic package design with respect to interfacing thermal, mechanical, and reliability analysis. The goal is to make reliability and maintainability an integral, real-time, and upfront part of the design process, such that the need to resubmit designs will be eliminated. The motivation behind this project was the fact that schedule constraints are often compromising the effectiveness and efficiency of the design process. To achieve the goal of CALCE/RAMCAD, a cohesive and extensible design environment for analysis and tradeoff tools was developed. A system executive controller that integrates tools for analysis while providing system transparency, design data management, and process management was developed to guide the user through the design process and provide direct access to the design tools. These developments required the integration of computer-aided design (CAD), artificial intelligence (AI), and decision support (DS) techniques. Attention to human factors and the use of interactive graphics were also instrumental in the development.     

How to avoid logarithms in comparisons with uniform random variables

In many algorithms for sampling from non-uniform distributions the logarithm of a uniform deviate must be compared with some test quantity. It is shown that all these comparisons can be done efficiently without calling a logarithm subprogram: two procedures for this task are presented and compared.