Single crystal tubes of beta alumina

Edge-defined, film-fed growth process allows both tubular shapes and single crystallinity to be achieved. Beta alumina in single crystal form makes possible membranes with improved conductivities. Single crystal membranes also eliminate problems associated with electrical short circuiting of membrane due to possible sodium metal diffusion

Ultralight reactive metal foams produced as structural shapes in space: System design

This autonomous experiment for foaming metals in space involved: (1) payload support structure; (2) furnace and foaming apparatus; (3) electronic controls; (4) battery power; and (5) metallurgy. Emphasis was laid on a modular design which was easily modifiable and which offered maximum durability, safety, and failure tolerance

MEETING PRIVATE GRADES AND STANDARDS IN TRANSITION AGRICULTURE: EXPERIENCES FROM THE ARMENIAN DAIRY INDUSTRY

One of the main trends emerging from the agroindustrialization process is the rise of 'grades and standards' (G&S) in food products. G&S were initially developed by the public sector to reduce transaction costs and ensure product quality and safety but have become a strategic instrument of competition in differentiated product markets (Reardon et al, 2001). Firms are using grades and standards to protect and develop brands in the international marketplace and in some cases to fill in for missing public standards. While producers in developed countries have the resources to meet these requirements, in developing countries these changes have tended to exclude small firms and farmers from participating in market growth, because of the implied investment requirements (Reardon et al, 2001). This is leading to already disadvantaged farmers in these countries being forced to produce basic subsistence food crops and become further excluded from the opportunity to join the global food industry. While past research has evaluated the effects and trends of G&S (Reardon, et al, 2001; Farina & Reardon, 2000; Reardon & Farina, 2002) the organizational structure to enable small farmers to meet these requirements has largely been overlooked. In this paper we use a theoretical contract enforcement framework to argue that private enforcement capital developed through the facilitation of an external aid agency can be an effective means for creating credible and sustainable relationships capable of meeting G&S. We draw upon theory from Cocks and Gow (2002), Oliver and Gow (2002) and Gow et al. (2000) to argue that in situations characterized by high discount rates and low reputation or trust levels (such as transition agriculture) that the use of a third party external enforcement agent can be used to provide the necessary linkage between the parties to facilitate transactions. Through the facilitation role of the external agency, private enforcement capital is developed between the firm and the farmers, opening the path for a sustainable mutually beneficial relationship. Empirical evidence is provided by the case of the United States Department of Agriculture Marketing Assistance Project (USDA MAP) in Armenia and its role in establishing farmer owned milk marketing cooperatives. By acting as an external facilitator in the initial establishment and ongoing development of milk supply cooperatives the USDA MAP has provided a solution to the dual market failure problems of reliable supply of the consistent quality of milk required by processors while enabling farmers access to markets and ensuring timely payment and therefore enabling farmers and firms to credibly contract for the collective marketing of their milk. Through the establishment of a unique and flexibly designed combination of leadership development, training in governance, financial management, dairy management, and quality improvement programs, the USDA MAP has assisted the groups in expanding the self enforcing range in such a manner that the cooperative should be capable of sustaining long term credible exchange relationships once the external agency withdraws. This is important as aid programs have often failed at ensuring sustainability once external management and financial support is removed. Data for this paper was collected through a series of semi-structured interview with USDA MAP staff, dairy processing firm managers, cooperative managers, and cooperative presidents during the fall of 2002, and over a two week period in March, 2003.Livestock Production/Industries,

MEETING PRIVATE GRADES AND STANDARDS IN TRANSITION AGRICULTURE: EXPERIENCES FROM THE ARMENIAN DAIRY INDUSTRY

Livestock Production/Industries,

Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

A model of the sintering exhibited by EB-PVD TBCs, based on principles of free energy minimization, was recently published by Hutchinson et al. In the current paper, this approach is applied to sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model

Accessibility of 3D Game Environments for People with Aphasia: An Exploratory Study

People with aphasia experience difficulties with all aspects of language and this can mean that their access to technology is substantially reduced. We report a study undertaken to investigate the issues that confront people with aphasia when interacting with technology, specifically 3D game environments. Five people with aphasia were observed and interviewed in twelve workshop sessions. We report the key themes that emerged from the study, such as the importance of direct mappings between users’ interactions and actions in a virtual environment. The results of the study provide some insight into the challenges, but also the opportunities, these mainstream technologies offer to people with aphasia. We discuss how these technologies could be more supportive and inclusive for people with language and communication difficulties

Electron scattering and transport in liquid argon

The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann's equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-section with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies.Comment: 32 pages, 16 figures; minor corrections, added 1 figur

Ice-lens formation and connement-induced supercooling in soils and other colloidal materials

We present a new, physically-intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil, and the confinement-induced supercooling of the water in the soil; a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good agreement with experiments, in particular explaining ice-lens pattern formation, and surges in heave rate associated with the growth of new lenses. Importantly for systems with no frozen fringe, ice-lens formation and frost heave can be predicted given only the unfrozen properties of the soil. We use our theory to estimate ice-lens growth temperatures obtaining quantitative agreement with experiments. The theory is generalizable to complex natural-soil scenarios, and should therefore be useful in the prediction of macroscopic frost heave rates