Using Simple Neural Networks to Correct Errors in Optical Data Transmission.

We have demonstrated the applicability of neural-network-based systems to the problem of reducing the effects of signal distortion, and shown that such a system has the potential to reduce the bit-error-rate in the digitized version of the analogue electrical signal derived from an optical data stream by a substantial margin over existing techniques

Effective scraping in a scraped surface heat exchanger: some fluid flow analysis

An outline of mathematical models that have been used to understand the behaviour of scraped surface heat exchangers is presented. In particular the problem of the wear of the blades is considered. A simple model, exploiting known behaviour of viscous flow in corners and in wedges, and accounting for the forces on the blade is derived and solutions generated. The results shows initial rapid wear but that the wear rate goes to zero

Reactive spark plasma synthesis of CaZrTi2O7 zirconolite ceramics for plutonium disposition

Near single phase zirconolite ceramics, prototypically CaZrTi 2 O 7 , were fabricated by reactive spark plasma sintering (RSPS), from commercially available CaTiO 3 , ZrO 2 and TiO 2 reagents, after processing at 1200 °C for only 1 h. Ceramics were of theoretical density and formed with a controlled mean grain size of 1.9 ± 0.6 μm. The reducing conditions of RSPS afforded the presence of paramagnetic Ti 3+ , as demonstrated by EPR spectroscopy. Overall, this study demonstrates the potential for RSPS to be a disruptive technology for disposition of surplus separated plutonium stockpiles in ceramic wasteforms, given its inherent advantage of near net shape products and rapid throughput

Laboratory based X-ray absorption spectroscopy of iron phosphate glasses for radioactive waste immobilisation: a preliminary investigation.

We report the application of laboratory based X-ray absorption spectroscopy to the speciation of Fe in iron phosphate glasses prepared by conventional and microwave melting. Analysis of the weak pre-edge features in Fe K-edge XANES data demonstrated glasses produced by microwave melting to have a higher fraction of reduced Fe2+ species, since microwave melts do not have sufficient time to equilibrate with the prevailing oxygen partial pressure, compared to counterparts produced by conventional melting. Furthermore, our laboratory XANES data are consistent with the formation of octahedral Fe2+ at the expense of tetrahedral Fe3+ species, with increasing Fe2+ content. These findings are consistent with the previous findings of our 57Fe Mossbauer study, synchrotron XANES data, and current understanding of the structure of iron phosphate glasses, and demonstrate the utility of laboratory based XANES for routine speciation of Fe in these and other materials

Age-related Changes in the Cellular Level of Amylase and Protein Synthesis in the Rat Parotid Gland

Age-related changes in the cellular content of secretory proteins and protein synthesis were studied in parotid glands of rats of various ages. The secretory protein content (determined by measuring the level of α-amylase activity) and the synthesis of proteins (assayed by the rate of incorporation of 3H-leucine into acid-insoluble proteins) decline with increasing age. Morphological and radioautographic studies of the gland indicate that the decline in protein synthesis is due to the reduction in the ability of secretory cells to synthesize proteins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67245/2/10.1177_00220345810600031401.pd

Hot isostatically pressed zirconolite wasteforms for actinide immobilisation

In order to demonstrate the deployment of Hot Isostatic Pressing (HIP) for the immobilisation of Pu stocks and residues, a series of active and inactive zirconolite formulations have been processed and characterised. In this instance, Ce, U, and Th have been applied as chemical surrogates for Pu4+. A range of formulations targeting isovalent Zr4+ site substitution (i.e. to simulate CaZr1-xPuxTi2O7) have been processed by HIP and characterised by powder X-ray diffraction, and scanning electron microscopy, in order to determine surrogate partitioning between the host zirconolite phase, and accessory phases that may have formed during the HIP process

Phase transition from a dx2−y2d_{x^2-y^2} to dx2−y2+dxyd_{x^2-y^2}+d_{xy} superconductor

We study the phase transition from a $d_{x^2-y^2}$ to $d_{x^2-y^2}+d_{xy}$ superconductor using the tight-binding model of two-dimensional cuprates. As the temperature is lowered past the critical temperature $T_c$, first a $d_{x^2-y^2}$ superconducting phase is created. With further reduction of temperature, the $d_{x^2-y^2}+d_{xy}$ phase is created at temperature $T=T_{c1}$. We study the temperature dependencies of the order parameter, specific heat and spin susceptibility in these mixed-angular-momentum states on square lattice and on a lattice with orthorhombic distortion. The above-mentioned phase transitions are identified by two jumps in specific heat at $T_c$ and $T_{c1}$.Comment: Latex file, 5 pages, 6 postscript figures, Accepted in Physical Review

Ce and U speciation in wasteforms for thermal treatment of plutonium bearing wastes, probed by L3 edge XANES

X-ray absorption spectroscopy was applied to understand the speciation of elements relevant to the immobilisation and disposal of radioactive plutonium bearing wastes, utilizing Ce as a Pu surrogate. Ce L3 XANES (X-ray Absorption Near Edge Structure) characterisation of a crystallised glass material produced by cold crucible plasma vitrification, at demonstration scale, evidenced incorporation as Ce3+ within the glass phase, providing an important validation of laboratory scale studies. U and Ce L3 XANES investigation of brannerite ceramics, U0.9Ce0.1Ti2O6, synthesized under oxidizing, neutral and reducing conditions, established the charge compensation mechanism as incorporation of Ce3+ through formation of U5+ and/or U6+ In each of these examples, X-ray Absorption Spectroscopy has provided a pivotal understanding of element speciation in relation to the mechanism of incorporation within the host wasteform intended for geological disposal

Australian water security and Asian food security: complexity and macroeconomics of sustainability

The thesis focuses on the macroeconomics of sustainable development and the extension to energy, water and food security, using a system dynamics approach, i.e. the methods of differential equations systems with initial values. The work is divided into three related parts that build a narrative concerning the interaction between economics, policy, natural resources and society. First, after reviewing the concepts of complexity in environmental security, a simple system comprising three coupled differential equations is used to explain the effects of macroeconomic business cycles on the exploitation of ecological resources, and from this is inferred an implied importance of averting business cycles. The concept of entropy production is used to represent the exploitation of ecological resources. The second part establishes a system methodology inspired by Post Keynesian economics to develop the Murray-Darling Basin Economy Simulation Model that links food production/water users and food consumers at the micro scale, to the macroeconomic system dynamics. The goal of this study is to integrate and analyze the ecological-economic system in the Murray-Darling basin. The concepts of entropy production, useful work and income distribution are used as a bridge between the micro and macro subsystems. The system parameters are estimated using an ecological-economic data set for the Murray-Darling basin and for Australia (where data of the Basin are unavailable) from 1978-2005, and the model is validated using data from 2006-2012. The results reveal important structural linkages between the two subsystems and are used to predict the consequences of business cycles and government intervention for the coordination of growth and sustainability. The third, and final, part presents the development of an ``Asian Food Security Risk Engine'' that predicts the threat of civil unrest from food insecurity in Asian developing countries. A basal characteristics index for each developing country in Asia is defined and evaluated. Based on these measures, and introducing the concept of flow of anger, we use a differential equation system to integrate the threat of food security, the trigger for food riots, and food policy. The system parameters are estimated using a data set tracking indexes for threat, trigger and policy for Asian developing countries from 2006-2008, and the model is validated using data from 2009-2012. The results show the possible alternative approaches to simulating threat severity from food insecurity and are used to predict the threat of social unrest due to food security for a given country one month ahead

Influence of transition metal charge compensation species on phase assemblage in zirconolite ceramics for Pu immobilisation

Immobilisation of Pu in a zirconolite matrix (CaZrTi2O7) is a viable pathway to disposition. A-site substitution, in which Pu4+ is accommodated into the Ca2+ site in zirconolite, coupled with sufficient trivalent M3+/Ti4+ substitution (where M3+ = Fe, Al, Cr), has been systematically evaluated using Ce4+ as a structural analogue for Pu4+. A broadly similar phase assemblage of zirconolite-2M and minor perovskite was observed when targeting low levels of Ce incorporation. As the targeted Ce fraction was elevated, secondary phase formation was influenced by choice of M3+ species. Co-incorporation of Ce/Fe resulted in the stabilisation of a minor Ce-containing perovskite phase at high wasteloading, whereas considerable phase segregation was observed for Cr3+ incorporation. The most favourable substitution approach appeared to be achieved with the use of Al3+, as no perovskite or free CeO2 was observed. However, high temperature treatments of Al containing specimens resulted in the formation of a secondary Ce-containing hibonite phase