Influence of convection and grain movement on globular equiaxed solidification

A two-phase volume averaging model was used to study convection and grain movement, and their influence on the globular equiaxed solidification. Both liquid and solid phases were treated as separate interpenetrating continua. The mass, momentum, species and enthalpy conservation equations for each phase and a grain transport equation were coupled. An ingot casting (Al-4 wt.% Cu) with near globular solidification morphology was simulated. Case studies with different modeling assumptions such as with and without grain movement, and with slip and non-slip boundary conditions for solid phase were presented and compared. Understanding of grain evolution and macrosegregation formation in globular equiaxed solidification was improved.     

Groundwork - a case study in landscape and amenity management

The Groundwork trusts have now been in operation for well over a decade and have implemented a wide range of projects across England and Wales. The origins and purposes of Groundwork are traced, and an overview of the types of project undertaken is presented. The relationship of the trusts to public and private sector funding, and the kinds of partnership involved, are examined. Many successes have been achieved in landscape renewal, although there have been some frictions with local authorities, and it is still difficult to make objective assessments of value for money or performance across a wide range of criteria. Nevertheless, the network of Groundwork trusts looks set to continue to offer a broad and flexible approach to environmental management.     

US housing problems,politics and policies in the 1990s

Housing policy in the US reflects its general approach to economic and social problems. Among all western democracies, the US relies most on private market forces to provide housing for its population. American housing policy emphasises bolstering market forces and minimising assistance for the poor. Despite its significant achievements (for example, two out of every three American households now owns its dwelling), the US is now facing a severe housing crisis, not only for the poor, but for a sizeable portion of the troubled middle class. To guarantee every American an opportunity to live in decent, safe and affordable housing, the US has to change national priorities and spend more on housing. But it also must spend better: reduce development costs, eliminate bureaucratic waste, and target assistance more efficiently. Following a review of past and current housing programmes, we outline a progressive housing policy agenda and then discuss the political obstacles and opportunities that confront such an ambitious plan.     

Book reviews

A Fourth Way? Privatization, Property and the Emergence of New Market Economies. Gregory S. Alexander & Grazyna Skapska (Eds). London, Routledge, 1994, xxiii + 336 pp., ISBN 0415906970 (HB), 0415906989 (PB)

From Public Housing to the Social Market. Rental Policy Strategies in Comparative Perspective. Jim Kemeny. London and New York, Routledge, 1995, 194 pp., £40.00

European Housing Finance. Single Market or Mosaic?. Will Bartlett & Glen Bramley (Eds). Oxford, The Alden Press, School for Advanced Urban Studies (SAUS) publication 12 (Bristol) 1994, 282 pp., £19.95, paperback, ISBN 1 873575 63 7

Housing, Financial Markets and the Wider Economy. David Miles. Chichester, John Wiley & Sons, 1994, 228 pp., £35.00

Women in the Housing Service. Marion Brion. London, Routledge, 1994, ISBN 0 415 08094 £45.00 Hardback

Slippery Customers: Estate Agents, The Public and Regulation. Michael Clarke, David Smith & Michael McConville. London, Blackstone Press, 1994, 295 pp., £19.95     

Calculation of Viscous EHL Traction for Squalane Using Molecular Simulation and Rheometry

Recently, remarkable agreement was reported between nonequilibrium molecular dynamics simulation and high-pressure Couette rheometry on squalane. We have utilized the viscosity-strain rate relationship obtained from this unique combination of experimental and simulation data along with high-pressure viscometer measurements to calculate the viscous traction curve in the elastohydrodynamic lubrication (EHL) regime. A comparison with measured traction at 0.57 and 1.29 GPa shows excellent agreement, confirming the validity of the measurements and simulations. Thus, we present for the first time, a successful calculation of EHL traction from the liquid shear response obtained from both molecular dynamics and rheometry.     

The pars intercerebralis of the locust brain: a developmental and comparative study.

The anterior midline of the brain, also known as the pars intercerebralis, contains the largest collection of neurosecretory cells in the central nervous system of the grasshopper. In this study, we use immunocytochemical, intracellular staining, and histological methods to establish the ontogenies of the various cell types in the brain midline, and show how these cells contribute to the pars intercerebralis of the adult brain. We show that the adult pars intercerebralis develops from three distinct embryonic cell groups: (1) the median neurosecretory cells, which derive from a subset of neuroblasts in the protocerebral hemispheres, and which project axons to the corpora cardiaca; (2) the paired primary commissure pioneers, which derive directly from the mesectoderm of the dorsal median domain and whose axons project to the ventral nerve cord via the midline tract; and (3) the six progeny of the median precursor in the dorsal median domain, which share a common axonal projection with the primary commissure pioneers. Since the adult pars intercerebralis is a fusion product of these independent cellular components, it can only be understood in terms of its origins in the embryonic brain. When the expression pattern of the TERM-1 antigen is compared in subsets of median neurosecretory cells in a wide range of insect orders, the results suggests a common organizational Bauplan for the pars intercerebralis. This hypothesis is supported by the identification of putative homologs of the grasshopper primary commissure pioneers in all these insects.     

BCI Competition 2003--Data set IIb: support vector machines for the P300 speller paradigm

We propose an approach to analyze data from the P300 speller paradigm using the machine-learning technique support vector machines. In a conservative classification scheme, we found the correct solution after five repetitions. While the classification within the competition is designed for offline analysis, our approach is also well-suited for a real-world online solution: It is fast, requires only 10 electrode positions and demands only a small amount of preprocessing.     

Micro-optical fiber switch for a large number of interconnectsusing a deformable mirror

In this letter, we demonstrate the limitations for 1 × N free space optical switch with a moving macro-lens. We use a deformable mirror to overcome these limitations. The adaptive mirror corrects for the aberrations. Power coupling efficiencies between 6 and 3 dB (including losses due to the optical elements) are feasible for an optical switch allowing up to 3019 receiver fibers     

Achieving Outstanding Mechanical Performance in Reinforced Elastomeric Composite Fibers Using Large Sheets of Graphene Oxide

A simple fiber spinning method used to fabricate elastomeric composite fibers with outstanding mechanical performance is demonstrated. By taking advantage of the large size of as‐prepared graphene oxide sheets (in the order of tens of micrometers) and their liquid crystalline behavior, elastomeric composite fibers with outstanding low strain properties have been fabricated without compromising their high strain properties. For example, the modulus and yield stress of the parent elastomer improved by 80‐ and 40‐fold, respectively, while maintaining the high extensibility of ～400% strain inherent to the parent elastomer. This outstanding mechanical performance was shown to be dependent upon the GO sheet size. Insights into how both the GO sheet size dimension and dispersion parameters influence the mechanical behavior at various applied strains are discussed.