Seasonal climate forecasts for more effective raingrown grain-cotton production systems

Cropping is a risky business. Our highly variable climate makes it difficult to decide how best to manage crops and cropping systems. What works well one year might not work well the next. To develop better risk management practices, this project uses the APSIM cropping systems model to examine the profitability and sustainability of a range of alternative dryland cotton/grain cropping systems throughout the northern grain region of eastern Australia. It involves working closely with farmer collaborators in Central Queensland, the Darling Downs, the northwest slopes of NSW and the Liverpool Plains

The Madden Julian Oscillation and its relationship with rainfall in Queensland

The Madden Julian Oscillation is a large-scale atmospheric phenomenon that is generated above the tropical Indian Ocean. It is associated with large convective systems that propagate eastward across the Pacific Ocean. Since it is an atmospheric event limited to the equatorial domain, it was believed that it has little effect on non-tropical regions. However, recent research found correlations between the positioning of the active Madden Julian Oscillation phase along the Equator and rainfall events northeast Australia. The correlations were significant throughout Queensland. The phenomenon is subject to a study by climate scientists at four Australian institutions. It aims to develop a simple predictive tool of rainfall events that are linked with the active phase of the Madden Julian Oscillation and that is applicable throughout Queensland and possible beyond. The outcome of this research is to be linked with agricultural production systems model in order to help Queensland farmers to better time planting and harvesting, as well as scheduling of contractors whose operations might be delayed by rain

The stability of immiscible viscous fingering in Hele-Shaw cells with spatially varying permeability

In this paper, we investigate the stability of immiscible viscous fingering in Hele-Shaw cells with spatially varying permeability, across a range of capillary numbers. We utilise a coupled boundary element - radial basis function (BE –RBF) numerical method that adapts and moves with the growing interface, providing an efficient, high accuracy scheme to track the interfacial displacement of immiscible fluids. By comparing the interfacial evolution and growth rate in varying permeability cells to that in uniform cells, we can assess the relative stability of the perturbations as a consequence of the variable permeability. Numerical experiments in Hele-Shaw cells with gradually varying permeability highlight 3 aperture effects that control the interfacial stability: (1) Gradients in the capillary pressure (2) Local changes in fluid mobility (3) Variation in the viscous pressure gradient. In low capillary number regimes, we find that aperture effect 1 and 2 dominate, which (relatively) stabilise interfacial perturbations in converging geometries and destabilise perturbations in diverging geometries. In high capillary number regimes, aperture effect 3 dominates meaning the relative stability transitions; the interface is destabilised in converging cells and stabilised in diverging cells. We find an upper bound critical capillary number Cagt at which the relative stability transitions in our gradually varying cell as 1000<Cagt<1250, which is independent of both α and ϵ0. This result is much lower than the value of Cagt=9139 predicted by linear stability theory, due to significant non-linear perturbation growth. This transition links the results found in previous works performed at low and high capillary numbers, providing new insight into the viscous fingering instability in variable permeability cells. To conclude, we present simulations in Hele-Shaw cells with large geometric heterogeneities and anisotropy, in order to demonstrate the significant fluid re-distribution that can occur due to localised variations in cell permeability. Using periodic permeability distributions, we show the significant re-distribution of fluid that can occur due to large capillary pressure gradients in the capillary limit, and the channelling of flow that can occur in the viscous limit along anisotropic features

CFD assessment of the effect of nanoparticles on the heat transfer properties of acetone/ZnBr2 solution

A potential novel working fluid for vapour absorption refrigeration utilising very low grade waste heat, is based on acetone and zinc bromide as the salt solution. A Computational Fluid Dynamics (CFD) model is presented of the fluid with zinc oxide nano-particles in a flat tube flow. A two phase type of model represents the zinc oxide nano-particles as a distinct fluid phase. The cases of laminar and turbulent flow are explored numerically for a wide range of acetone and nanoparticles concentrations. The velocity is varied between 1.5 and 6 ms−1, representing typical heat exchanger conditions. Reynolds number depends significantly on the solution concentration. Heat transfer coefficient increases with Re, by turbulent mixing, and with the concentration of nanoparticles and of acetone by the enhanced thermal diffusivity. The shear wall stress is not affected by changing the concentration of nano-particles. The nano-fluid is demonstrated to work well for heat transfer enhancement over the base fluid; the further issue of suspension of the nano-particles in the solution is explored experimentally. The nano-fluid can be achieved by ultra-sonic excitation, with a settling time in the order of several hours. Subject to the particle suspension time being increased, this fluid combination is a good candidate for the application considered

CFD multiphase modelling of the acetone condensation and evaporation process in a horizontal circular tube

With increasing demands on energy efficiency, the use of low grade waste heat using vapour absorption refrigeration systems (VARS) are receiving renewed interest. One idea is to use the combination of acetone and zinc bromide as the salt solution, which allows use of temperatures in the order of 10s of C above ambient conditions. This work numerically models acetone phase change in the evaporator and condenser in order to indicate how improvements can be made in these components of the system. ANSYS® Fluent finite volume method CFD is used to produce volume of fluid (VOF) and mixture multiphase flow models to investigate the evaporation and the condensation of acetone in a horizontal circular tube. Different velocities and temperatures were taken in each process to explore the effect of these variables in the system. A user defined function (UDF) is used to calculate the volume fraction of the phases. For the evaporation case, the heat transfer coefficient increases with increasing velocity and the temperature difference between the inlet flow and the wall, as expected. The mass transfer rate decreases with increasing the flow rate or decreasing the wall temperature, from 0.045 kg/m 3 .s at 0.01 m/s to 0.016 kg/m 3 .s at 0.06 m/s and it drops from 0.044 to 0.023 kg/m 3 .s by changing the temperature just from 300 to 298 K. This demonstrates a reduction in specific heat transfer to the liquid despite the higher wall heat transfer coefficient. In the condenser, vapour quality decreases along the tube as liquid acetone is created with reduced flow rate. Vapour volume fraction at the outlet section drops from 0.74 to 0.168 by increasing the ingoing velocity from 0.01 to 0.06 m/s. Increasing the rate of condensation will increase the liquid in the evaporator, which increase the evaporation rate then increase the performance of the VARS. This demonstrates the importance of controlling the temperature and the flow rate in the VARS for generate more refrigerants

Global Implications of Recent Innovations in U.S. Collective Bargaining

La négociation collective aux États-Unis se polarise de plus en plus sur les extrêmes de conflit et de coopération. À un extrême se trouve l'effondrement de la négociation en grèves acharnées voire même la fuite des employeurs devant les relations syndicales-patronales. À l'autre extrême se trouve le partenariat conjoint qui touche les décisions sur presque tous les aspects du fonctionnement des affaires. Plusieurs facteurs domestiques et internationaux provoquent cette polarisation du processus de négociation.Les plus importants sont: l'accroissement de la concurrence internationale, les changements démographiques, et les choix stratégiques des entreprises et des syndicats. Ce texte ne porte que sur un de ces deux extrêmes, notamment les innovations récentes de négociation de forme coopérative. On soutient que ces innovations peuvent faciliter des changements dans les lieux de travail variés, autant aux États-Unis qu'ailleurs. Cette conclusion est basée sur des expériences personnelles dans plus de cent contextes, ainsi que sur l'analyse des tendances globales en relations professionnelles. Toutefois, il est important de comprendre la grande variété des pratiques d'innovation possibles et les nombreux dilemmes et complexités qui sont liés aux initiatives récentes.Les innovations portent plusieurs noms, dont la négociation de gain mutuel, la négociation d'intérêt, la négociation gagnant-gagnant et la négociation à cible spécifique. Bien que toutes ces approches à la négociation partagent des caractéristiques communes, il existe des différences importantes dans le centre d'intérêt, la possibilité et les résultats associés à chaque approche. En premier lieu, on examine la grande variété des approches de négociation de forme coopérative. Ceci peut varier d'une approche commune et ponctuelle afin de régler un seul problème à la construction d'un accord compréhensif durable fondé sur ces principes. Ensuite, on étudie en particulier la négociation à cible spécifique, qui est un des modèles les plus compréhensifs et les plus utilisés. Cette approche est remarquable car elle implique la totalité de la main-d’œuvre dans le processus de négociation, et elle élargit considérablement la portée des négociations. Enfin, on explore quelques implications multiculturelles liées à l'application de nouveaux modèles de négociation ailleurs qu'aux États-Unis.La prémisse principale de cette analyse est que les relations syndicales patronales apportent inévitablement un mélange de motifs et d'intérêts communs et concurrents dans les relations du travail. Les relations du travail en soi auront toujours des mécanismes ou des processus pour faire sortir et résoudre les conflits. En se concentrant sur les innovations de forme coopérative, on reconnaît non seulement les dimensions conflictuelles de ces relations, mais on soutient que le succès même des efforts coopératifs dépend de la capacité de régler les questions qui entraînent énormément de division.This paper deals with recent innovations in cooperative forms of collective bargaining. The authors begin by reviewing the wide range of highly cooperative approaches to negotiations. They then focus on a fairly comprehensive model, which is termed "target-specific bargaining". Finally, they explore some of the cross-cultural implications associated with applying the new forms of bargaining outside the North American context in two very different countries, Poland and South Africa

The EUROHIS-QOL 8-Item Index: Comparative Psychometric Properties to Its Parent WHOQOL-BREF

AbstractObjectivesTo test the psychometric properties of the EUROHIS-QOL 8-item index, a shortened version of the World Health Organization Quality of Life Instrument-Abbreviated Version (WHOQOL-BREF).MethodsThe sample consisted of 2359 subjects identified from primary care settings, with 1193 having a confirmed diagnosis of depression. Data came from six countries (Australia, Brazil, Israel, Russia, Spain, and the United States) involved in a large international study, the Longitudinal Investigation of Depression Outcomes. The structure of the EUROHIS-QOL 8-item index follows that of the WHOQOL-BREF assessment. Internal consistency was measured by using Cronbach's alpha. Convergent validity was assessed by using correlations with different measures for mental health (Symptom Checklist 90), physical health (self-evaluation), and quality of life (WHOQOL-BREF and short form 36 health survey). Discriminant group validity was assessed between diagnosed depressed and nondepressed patients. Differential item functioning and unidimensionality were analyzed by using Rasch analysis. Factor structure was assessed with structural equation modeling analyses.ResultsInternal consistency was acceptable (ranged between 0.72 and 0.81 across countries), and the index discriminated well between depression (t = 6.31–20.33; P < 0.001) across all countries. Correlations between the EUROHIS-QOL 8-item index and different measures—Symptom Checklist 90 (r = −0.42), physical health (r = −0.42), WHOQOL-BREF domains (r = 0.61–0.77), and short form 36 health survey (r = 0.58)—were all significant (P < 0.001). The index is unidimensional with desired item fit statistics. Two items (“daily living activities” and “enough money to meet your needs”) had residuals exceeding 4. Differential item functioning was observed with general quality of life, general health, relationships, and home items for age. A common one-factor structure with acceptable fit was identified in three out of six countries (comparative fit index = 0.85, root mean square error of approximation = 0.11).ConclusionsThe EUROHIS-QOL 8-item index showed acceptable cross-cultural performance and a satisfactory discriminant validity and would be a useful measure to include in studies to assess treatment effectiveness

Using seasonal climate forecasts for more effective grain-cotton production systems

The overall aim of this project is to significantly improve financial profitability, economic efficiency and resource risk management of dryland grain/cotton systems through effective use of seasonal climate forecasts and quantification of climatic variability

Lax Logical Relations

Lax logical relations are a categorical generalisation of logical relations; though they preserve product types, they need not preserve exponential types. But, like logical relations, they are preserved by the meanings of all lambda-calculus terms.We show that lax logical relations coincide with the correspondences of Schoett, the algebraic relations of Mitchell and the pre-logical relations of Honsell and Sannella on Henkin models, but also generalise naturally to models in cartesian closed categories and to richer languages