Measurements of thick target fission yields as a probe of fission excitation functions for deep sub-barrier energies

A close-geometry experimental technique has been developed and used to measure thick target fission yields for protons on ²³⁸U from 4.2 to 12 MeV. Fission fragments were detected at back angles by an annular photo-voltaic detector in coincidence with γ-ray registered in large NaI(Tl) detector. The neutron induced fission background was monitored by a detector on the downstream side of the thick target. Measured yields compare well with those calculated from published thin target cross sections. This method has the required sensitivity to carry out measurements at still lower energies where recent measurements give conflicting findings.     

A soft configuration model for wearless sliding friction

A phenomenological model of soft potential configurations is proposed to describe sliding friction in the wearless regime. This model accounts for the static and dynamic behavior. The physical origin of the logarithmic speed or time dependence for the friction coefficient is described. Means to control the friction coefficient by controlling the soft defect density are discussed. This revised version was published online in September 2006 with corrections to the Cover Date.     

Does anticipation training affect drivers' risk taking?

Skill and risk taking are argued to be independent and to require different remedial programs. However, it is possible to contend that skill-based training could be associated with an increase, a decrease, or no change in risk-taking behavior. In 3 experiments, the authors examined the influence of a skill-based training program (hazard perception) on the risk-taking behavior of car drivers (using video-based driving simulations). Experiment 1 demonstrated a decrease in risk taking for novice drivers. In Experiment 2, the authors examined the possibilities that the skills training might operate through either a nonspecific reduction in risk taking or a specific improvement in hazard perception. Evidence supported the latter. These findings were replicated in a more ecological context in Experiment 3, which compared advanced and nonadvanced police drivers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conference diary

A variational higher-order theory for bending and stretching of linearly elastic orthotropic beams including the deformations due to transverse shearing and stretching of the transverse normal fibre is presented. The theory assumes a linear distribution for the longitudinal displacement and a parabolic variation of the transverse displacement across the thickness. Additionally, independent expansions are introduced for the through-thickness displacement gradients with the requirement of a least-square compatibility for the transverse strains and the satisfaction of exact stress boundary conditions at the top/bottom beam surfaces. The theory is shown to be well suited for finite element development requiring simple C⁰- and C^?1- continuous displacement interpolation fields. To demonstrate the computational utility of the theory, a simple two-node stretching-bending finite element is formulated. The analytic and finite element results are obtained for a simple bending problem for which an exact elasticity solution is available. It is shown that the inclusion of the transverse normal deformation in the present theory enables improved displacement, strain and stress predictions, particularly, in the analysis of deep beams.     

Improved approaches to the exact solution of the machine covering problem

For the basic problem of scheduling a set of n independent jobs on a set of m identical parallel machines with the objective of maximizing the minimum machine completion time—also referred to as machine covering—we propose a new exact branch-and-bound algorithm. Its most distinctive components are a different symmetry-breaking solution representation, enhanced lower and upper bounds, and effective novel dominance criteria derived from structural patterns of optimal schedules. Results of a comprehensive computational study conducted on benchmark instances attest to the effectiveness of our approach, particularly for small ratios of n to m.     

3GPP LTE‐Assisted Wi‐Fi‐Direct: Trial Implementation of Live D2D Technology

This paper is a first‐hand summary on our comprehensive live trial of cellular‐assisted device‐to‐device (D2D) communications currently being ratified by the standards community for next‐generation mobile broadband networks. In our test implementation, we employ a full‐featured 3GPP LTE network deployment and augment it with all necessary support to provide real‐time D2D connectivity over emerging Wi‐Fi‐Direct (WFD) technology. As a result, our LTE‐assisted WFD D2D system enjoys the required flexibility while meeting the existing standards in every feasible detail. Further, this paper provides an account on the extensive measurement campaign conducted with our implementation. The resulting real‐world measurements from this campaign quantify the numerical effects of D2D functionality on the resultant system performance. Consequently, they shed light on the general applicability of LTE‐assisted WFD solutions and associated operational ranges.     

On Automation in the Verification of Software Barriers: Experience Report

We present an experience report on automating the verification of the software barrier synchronization primitive. The informal specification of the primitive is: when a thread calls the software barrier function, the thread halts until all other threads call their instances of the software barrier function. A successful software barrier call ensures that each thread has finished its portion of work before the threads start exchanging the results of these portions of work. While software barriers are widely used in parallel versions of major numerical algorithms and are indispensable in scientific computing, software barrier algorithms and their implementations scarcely have been verified. We improve the state of the art in proving the correctness of the major software barrier algorithms with off-the-shelf automatic verification systems such as Jahob, VCC, Boogie, Spin and Checkfence. We verify a central barrier, a C implementation of a barrier, a static tree barrier, a combining tree barrier, a dissemination barrier, a tournament barrier, a barrier with its client and a barrier on a weak memory model. In the process, we introduce a novel theorem proving method for proving validity of formulas containing cardinalities of comprehensions and improve the capabilities of one of the verification systems. Based on our experience, we propose new challenges in the verification of software barriers.     

Book reviews

Cities in Civilisation

Peter Hall. Weidenfeld & Nicolson, London, 1998. ISBN 0297842196 (hardback). 1,169 pp.; bibliography and index. RRP $75.00

A Study of Town Life:. Living Standards in the City of York 100 Years After Rowntree

Meg Huby, Jonathan Bradshaw and Anne Corden York Publishing Services, York, 1999. ISBN 1902633229 (paperback). 54 pp.; bibliography. RRP $36.50

Future Makers, Future Takers: Life in Australia, 2050

Kenneth Douglas Cocks. University of New South Wales Press, Sydney, 1999. ISBN 086840473X (paperback). 331 pp.; bibliography and index. RRP $39.95

Constructing Suburbs: Competing Voices in a Debate over Urban Growth

Ann Forsyth. Gordon & Breach, Amsterdam, 1999. ISBN 9057005271 (paperback). 195 pp.: bibliography and index. RRP $36.00