A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation Rings

We present near-infrared (H- and K-band) integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. The data, obtained at the Very Large Telescope with the SINFONI spectrograph, are used to construct maps of various emission lines that reveal the individual star forming regions ("hot spots") delineating the rings. We derive the morphological parameters of the rings, and construct velocity fields of the stars and the emission line gas. We propose a qualitative, but robust, diagnostic for relative hot spot ages based on the intensity ratios of the emission lines Brackett gamma, HeI, and [FeII]. Application of this diagnostic to the data presented here provides tentative support for a scenario in which star formation in the rings is triggered predominantly at two well-defined regions close to, and downstream from, the intersection of dust lanes along the bar with the inner Lindblad resonance.Comment: 45 pages incl. 4 tables and 12 (mostly color) figures. Accepted for publication in AJ. A version with full resolution figures can be obtained at ftp://ftp.rssd.esa.int/pub/tboeker/SINFONI/ms.pd

Salinity and waterlogging on the Esperance Downs Research Station

Details the situation on the station so that the demonstration and research programs can be designed and the effect of the treatments assessed. Past work on the station has been briefly summarised and the results of geophysical surveys and additional drilling are given. Surveys of electromagnetic terrain conductivities have shown where salinity is most serious at present. The most deeply penetrating method may have identified areas likely to developing salinity in future

Transport coefficients of multi-particle collision algorithms with velocity-dependent collision rules

Detailed calculations of the transport coefficients of a recently introduced particle-based model for fluid dynamics with a non-ideal equation of state are presented. Excluded volume interactions are modeled by means of biased stochastic multiparticle collisions which depend on the local velocities and densities. Momentum and energy are exactly conserved locally. A general scheme to derive transport coefficients for such biased, velocity dependent collision rules is developed. Analytic expressions for the self-diffusion coefficient and the shear viscosity are obtained, and very good agreement is found with numerical results at small and large mean free paths. The viscosity turns out to be proportional to the square root of temperature, as in a real gas. In addition, the theoretical framework is applied to a two-component version of the model, and expressions for the viscosity and the difference in diffusion of the two species are given.Comment: 31 pages, 8 figures, accepted by J. Phys. Cond. Matte

A study of stiffness, residual strength and fatigue life relationships for composite laminates

Qualitative and quantitative exploration of the relationship between stiffness, strength, fatigue life, residual strength, and damage of unnotched, graphite/epoxy laminates subjected to tension loading. Clarification of the mechanics of the tension loading is intended to explain previous contradictory observations and hypotheses; to develop a simple procedure to anticipate strength, fatigue life, and stiffness changes; and to provide reasons for the study of more complex cases of compression, notches, and spectrum fatigue loading. Mathematical models are developed based upon analysis of the damage states. Mathematical models were based on laminate analysis, free body type modeling or a strain energy release rate. Enough understanding of the tension loaded case is developed to allow development of a proposed, simple procedure for calculating strain to failure, stiffness, strength, data scatter, and shape of the stress-life curve for unnotched laminates subjected to tension load

Investigation of a saline valley on Allandale Research Farm

Geophysical surveys and drilling were used to investigate a saline valley on Allandale Research Farm. These techniques showed that the geology is controlling the location of two main areas of saline seeps and they identified another area at risk of increased salinity. They were also used to obtain information on the groundwater system and to assist in making management recommendations. Electromagnetic terrain conductivity surveys showed that the most saline soils occurred upstream of a cross-cutting magnetic anomaly caused by a dolerite dyke. A seismic survey showed that the anomaly coincided with a bedrock rise. This bedrock rise restricts groundwater flow through the catchment and forces saline groundwater to the surface where it evaporates causing salts to build up in the soil profile. A second area of saline surface soils occurs further downstream. Outcrops of granite in the creek indicate that another bedrock rise is the cause for the location of this seep. A third area in the valley upslope from the main saline area has a high subsoil conductivity and is immediately upslope of a second magnetic anomaly. This area may become more saline in the future. Drilling confirmed the seismic profile near the dolerite dyke in the main saline area. It also indicated that deep groundwater pressures are above ground level along the whole of the valley/ becoming higher with increased distance downstream. The quality of the groundwater ranged from 3,500 to 6,500 mg.Cl-1/L. Three recommendations are made for the area: (i) the construction of an interceptor drain/ upslope of each saline area, to reduce waterlogging; (ii) fencing the saline areas, and revegetating to salt tolerant grasses, bushes and trees; (iii) limiting recharge on coarse textured soils in the catchment above the valley by growing crops and/or trees with high evapotranspiration potentials

Modelling Simple Feature Creation in Selective Laser Sintering

A two dimensional finite difference thermal sintering model has been created to describe the Selective Laser Sintering process(SLS). It includes thermal property variation with position and temperature, and especially adaptive meshing to refine information in regions of high temperature gradients. It has been used to predict density and temperature in both single and multi layer sintering operations, corresponding to experimental results. This paper will present comparisons of theory and experiment for the SLS of simple geometries such as blocks, steps, and cylinders.Mechanical Engineerin

Lorentz transformation and vector field flows

The parameter changes resulting from a combination of Lorentz transformation are shown to form vector field flows. The exact, finite Thomas rotation angle is determined and interpreted intuitively. Using phase portraits, the parameters evolution can be clearly visualized. In addition to identifying the fixed points, we obtain an analytic invariant, which correlates the evolution of parameters.Comment: 11 pages, 3 figures. Section IV revised and title change