Twice-told tales.

The first book with Hawthorne's name on the title page--cf. N. E. Browne, A bibliography of ... Hawthorne.

Teamwork to save soil and increase production /

A study of soil erosion on the Honey Hollow creek watershed, Bucks County, Pennsylvania.

Teamwork to save soil and increase production /

A study of soil erosion on the Honey Hollow creek watershed, Bucks County, Pennsylvania.

Fundamental research on raw materials used for electron emissivity on indirectly heated cathodes. Interim technical report.

1st has subtitle: First quarterly progress report; 2d-6th, Second-Sixth quarterly periodic status report.

In situ damage detection in frame structures through coupled response measurements

Due to the existence of global modes and local modes of the neighbouring members, damage detection on a structure is more challenging than damage on isolated beams. Detection of an artificial circumferential crack on a joint in a frame-like welded structure is studied in this paper using coupled response measurements. Similarity to real engineering structures is maintained in the fabrication of the test frame. Both the chords and the branch members have hollow sections and the branch members have smaller sizes. The crack is created by a hacksaw on a joint where a branch meets the chord. The methodology is first demonstrated on a single hollow section beam. The test results are then presented for the damaged and undamaged frame. The existence of the damage is clearly observable from the experimental results. It is suggested that this approach offers the-potential to detect damage in welded structures such as cranes, mining equipment, steel-frame bridges, naval and offshore structures. (C) 2003 Elsevier Ltd. All rights reserved.

Advances in vascular tissue engineering

Coronary and peripheral artery bypass grafting is commonly used to relieve the symptoms of vascular deficiencies, but the Supply Of autologous artery or vein may not be sufficient or suitable for multiple bypass or repeat procedures, necessitating the use of other materials. Synthetic materials are suitable for large bore arteries but often thrombose when used in smaller arteries. Suitable replacement grafts must have appropriate characteristics, including resistance to infection, low immunogenicity and good biocompatability and thromboresistance, with appropriate mechanical and physiological properties and cheap and fast manufacture. Current avenues of graft development include coating synthetic grafts with either biological chemicals or cells with anticoagulatory properties. Matrix templates or acellular tubes of extracellular matrix (such as collagen) may be coated or infiltrated with cultured cells. Once placed into the artery, these grafts may become colonised by host cells and gain many of the properties of normal artery. Tissue-engineered blood vessels may also be formed from layers of human vascular cells grown in culture. These engineered vessels have many of the characteristics of arteries formed in vivo. Artificial arteries may be also be derived from peritoneal granulation tissue in body bioreactors by adapting the body's natural wound healing response to produce a hollow tube. (C) 2003 Elsevier Inc. All rights reserved.

Galvanic corrosion of magnesium alloy AZ91D in contact with an aluminium alloy, steel and zinc

An investigation was carried out into the galvanic corrosion of magnesium alloy AZ91D in contact with zinc, aluminium alloy A380 and 4150 steel. Specially designed test panels were used to measure galvanic currents under salt spray conditions. It was found that the distributions of the galvanic current densities on AZ91D and on the cathodes were different. An insulating spacer between the AZ91D anode and the cathodes could not eliminate galvanic corrosion. Steel was the worst cathode and aluminium the least aggressive to AZ91D. Corrosion products from the anode and cathodes appeared to be able to affect the galvanic corrosion process through an alkalisation, passivation, poisoning effect or shortcut effect. (C) 2003 Elsevier Ltd. All rights reserved.

Evaluation of the BEASY program using linear and piecewise linear approaches for the boundary conditions

The boundary element method (BEM) was used to study galvanic corrosion using linear and logarithmic boundary conditions. The linear boundary condition was implemented by using the linear approach and the piecewise linear approach. The logarithmic boundary condition was implemented by the piecewise linear approach. The calculated potential and current density distribution were compared with the prior analytical results. For the linear boundary condition, the BEASY program using the linear approach and the piecewise linear approach gave accurate predictions of the potential and the galvanic current density distributions for varied electrolyte conditions, various film thicknesses, various electrolyte conductivities and various area ratio of anode/cathode. The 50-point piecewise linear method could be used with both linear and logarithmic polarization curves.

Crack detection in welded mechanical structures using coupled vibrations

Detection of a fatigue crack in a welded frame structure is studied in this paper using coupled response measurements. Similarity to real engineering structures is maintained in the fabrication of the test frame with hollow section chords and branch members. The fatigue crack was created by a special reciprocating mechanism that generates cyclic stress on a beam member of the structure. The methodology of coupled response measurements is first demonstrated on a single hollow section beam by analytical simulation and experimental validation. The issues of using this approach for fatigue crack detection in real structures are then examined. Finally, the experimental results of the frame under different scenarioes are presented. The existence of the crack is clearly observable from the FRF plots. It is suggested that this approach offers the potential to detect cracks in welded frame structures and is a useful tool for routine maintenance work and health assessment.

Electrodeposition of composite copper/liquid-containing microcapsule coatings

This paper presents results on the preparation of microcapsules containing liquid organosilica, and their co-deposition with copper in an acidic copper electrolyte onto a carbon steel cathode to form a copper/microcapsule composite coating. Microscopic analyses of the surface and the cross-section of the coating confirm the incorporation of the liquid-containing microcapsules in the coating layer. The influence of microcapsules in the electrolyte on the cathode polarization, as well as that of process conditions on the microcapsule inclusion, is also discussed. (C) 2004 Kluwer Academic Publishers.

Comparative study of Li, Na, and K adsorptions on graphite by using ab initio method

A comprehensive study has been conducted to compare the adsorptions of alkali metals (including Li, Na, and K) on the basal plane of graphite by using molecular orbital theory calculations. All three metal atoms prefer to be adsorbed on the middle hollow site above a hexagonal aromatic ring. A novel phenomenon was observed, that is, Na, instead of Li or K, is the weakest among the three types of metal atoms in adsorption. The reason is that the SOMO (single occupied molecular orbital) of the Na atom is exactly at the middle point between the HOMO and the LUMO of the graphite layer in energy level. As a result, the SOMO of Na cannot form a stable interaction with either the HOMO or the LUMO of the graphite. On the other hand, the SOMO of Li and K can form a relatively stable interaction with either the HOMO or the LUMO of graphite. Why Li has a relatively stronger adsorption than K on graphite has also been interpreted on the basis of their molecular-orbital energy levels.

Economic Incentives to Conserve Wildlife on Private Lands: Analysis and Policy

Some believe that provision of private property rights in wildlife on private land provides a powerful economic incentive for nature conservation because it enables property owners to market such wildlife or its attributes. If such marketing is profitable, private landholders will conserve the wildlife concerned and its required habitat. But land is not always most profitably used for exploitation of wildlife, and many economic values of wildlife (such as non-use economic values) cannot be marketed. The mobility of some wildlife adds to the limitations of the private-property approach. While some species may be conserved by this approach, it is suboptimal as a single policy approach to nature conservation. Nevertheless, it is being experimented with, in the Northern Territory of Australia where landholders had a possibility of harvesting on their properties a quota of eggs and chicks of red-tailed black cockatoos for commercial sale. This scheme was expected to provide an incentive to private landholders to retain hollow trees essential for the nesting of these birds but failed. This case and others are analysed. Despite private-property failures, the long-term survival of some wildlife species depends on their ability to use private lands without severe harassment, either for their migration or to supplement their available resources, for example, the Asian elephant. Nature conservation on private land is often a useful, if not essential, supplement to conservation on public lands. Community and public incentives for such conservation are outlined.

Molten carbonate fuel cells

Over the past 12 months, developments in both porous and non-porous materials for the molten carbonate fuel cell (MCFC) should lead to significantly increased stack lifetimes. Lithium-sodium carbonate is emerging as the material of choice for the electrolyte and has been tested in a 10 kW scale stack. Several new cathode materials, with lower dissolution rates in the electrolyte than state-of-the-art NiO, have been tested. However a significant finding is that the dissolution rate of NiO can also be reduced by an order of magnitude by preparing it as a functional nanomaterial. Although most developers continue to use nickel anodes, recent tests with ceramic oxides anodes open up the prospects of reduced carbon deposition and future cells running directly on dry methane. (c) 2004 Published by Elsevier Ltd.

Influence of geometry on galvanic corrosion of AZ91D coupled to steel

The influence of geometric factors on the galvanic current density distribution for AZ91D coupled to steel was investigated using experimental measurements and a BEM model. The geometric factors were area ratio of anode/cathode, insulation distance between anode and cathode, depth of solution film covering the galvanic couple and the manner of interaction caused by two independent interacting galvanic couples. The galvanic current density distribution calculated from the BEM model was in good agreement with the experimental measurements. The galvanic current density distribution caused by the interaction of two independent galvanic couples can be reasonably predicted as the linear addition of the galvanic current density caused by each individual galvanic couple. (c) 2005 Elsevier Ltd. All rights reserved.

Applying network analysis to the conservation of habitat trees in urban environments: a case study from Brisbane, Australia

In Australia more than 300 vertebrates, including 43 insectivorous bat species, depend on hollows in habitat trees for shelter, with many species using a network of multiple trees as roosts, We used roost-switching data on white-striped freetail bats (Tadarida australis; Microchiroptera: Molossidae) to construct a network representation of day roosts in suburban Brisbane, Australia. Bats were caught from a communal roost tree with a roosting group of several hundred individuals and released with transmitters. Each roost used by the bats represented a node in the network, and the movements of bats between roosts formed the links between nodes. Despite differences in gender and reproductive stages, the bats exhibited the same behavior throughout three radiotelemetry periods and over 500 bat days of radio tracking: each roosted in separate roosts, switched roosts very infrequently, and associated with other bats only at the communal roost This network resembled a scale-free network in which the distribution of the number of links from each roost followed a power law. Despite being spread over a large geographic area (> 200 km(2)), each roost was connected to others by less than three links. One roost (the hub or communal roost) defined the architecture of the network because it had the most links. That the network showed scale-free properties has profound implications for the management of the habitat trees of this roosting group. Scale-free networks provide high tolerance against stochastic events such as random roost removals but are susceptible to the selective removal of hub nodes. Network analysis is a useful tool for understanding the structural organization of habitat tree usage and allows the informed judgment of the relative importance of individual trees and hence the derivation of appropriate management decisions, Conservation planners and managers should emphasize the differential importance of habitat trees and think of them as being analogous to vital service centers in human societies.