The Stokes problem for the ellipsoid using ellipsoidal kernels

A brief review of Stokes' problem for the ellipsoid as a reference surface is given. Another solution of the problem using an ellipsoidal kernel, which represents an iterative form of Stokes' integral, is suggested with a relative error of the order of the flattening. On studying of Rapp's method in detail the procedures of improving its convergence are discussed

Modelling barriers for coal dust suppression

Airborne dust originating from the transport and storage of raw coal has detrimental effects on the environment. Warkworth Mining is seeking to reduce the dust emissions caused by the dumping of raw coal at their facility in Singleton, NSW. The suggested strategy was the construction of windbreaks, for which commercial designs exist. The MISG was asked to advise on the placement and design of such windbreaks. The problem was approached by studying results in the literature on windbreak design, selecting a few possible configurations, and then testing these by solving numerically for the wind velocity around the dumping site. It was concluded that a long fence on the upwind side of the dumping hoppers would provide moderate protection, but would interfere with current operating procedures. As a better option, a long downwind fence immediately behind the hoppers would provide a similar reduction in the dust emission, and allow more effective use of water sprays. Although fine details of the fence design could not be modelled numerically, we concluded that it was desirable for the fence to have an angled overhang in the vicinity of the hoppers, and a porous section near the base to reduce turbulent flows

Effect of agent concentration in ultrasound super- resolution imaging at clinically low frequency

Imaging of microvasculature can be valuable for the diagnosis and treatment monitoring of cancer and other diseases. Ultrasound has the potential due to its excellent spatial and temporal resolution. Super-resolution ultrasound imaging using contrast enhanced ultrasound localization microscopy is able to visualize microvasculature beyond the wave diffraction limit. The microbubble based super-resolution depends on controlling the bubble concentration, which needs to be low enough to locate isolated microbubbles. However too low a concentration will prolong the data acquisition. The aim of the thesis was to evaluate the impact of microbubble concentration on super-resolution ultrasound imaging, and to improve the signal processing in super-resolution imaging. First, various concentrations of microbubble contrast agents (6×10^3 to 1.5×10^6particles/ml) were injected into a 200 microns cross-tube flow phantom. The experimental results show that the concentration affects the resolution of the cross-tube images. When the concentration is lower than the 1.5×10^5particles/ml, two tubes in a selected region of interest near the intersection that are 370 microns apart can be separated, which is close to the expected distance (390 microns). Second, the comprehensive effects of data acquisition time and concentration on imaging resolution were studied. The preferred range of concentration was determined between 1.5×10^4 to 6×10^4particles/ml. This result can be used to better inform data acquisition in the further research. Third, a weight adaptive denoising method based on morphology was developed to remove noises which were produced in the step of microbubble detection at the preferred range of concentration. Therefore, the resolution and the accuracy of the velocity map were further improved.Open Acces

Forest Species Identification with High Spectral Resolution Data

Data collected over the Sleeping Bear Sand Dunes Test Site and the Saginaw Forest Test Site (Michigan) with the JPL Airborne Imaging Spectrometer and the Collins' Airborne Spectroradiometer are being used for forest species identification. The linear discriminant function has provided higher identification accuracies than have principal components analyses. Highest identification accuracies are obtained in the 450 to 520 nm spectral region. Spectral bands near 1,300, 1,685 and 2,220 nm appear to be important, also

Oil Blending: Mixing and Contamination

The Shell Company of Australia has a frequent need to blend lubricants. Blending, sometimes involving three lubricant oils and additives, takes place by jet mixing in large tanks of typically 45,000 titres capacity. The jets are driven by pumps with typical volume throughput of up to 1,000 titres per minute, and typical blending times may be as long as one or two hours. The jet blending process was investigated in a number of ways at the Study Group. These included: simple estimates for blending times, theoretical and experimental description of jet behaviour, development of a simple compartment model for the blending process, and several large scale computer simulations of the jet-induced motion using a commercial Computational Fluid Dynamics package. In addition, the sedimentation of contaminant particles in the tanks was investigated. This overall investigation, using a variety of approaches, gave a good knowledge of the blending process

Gravitational Lensing Statistics as a Probe of Dark Energy

By using the comoving distance, we derive an analytic expression for the optical depth of gravitational lensing, which depends on the redshift to the source and the cosmological model characterized by the cosmic mass density parameter $\Omega_m$, the dark energy density parameter $\Omega_x$ and its equation of state $\omega_x = p_x/\rho_x$. It is shown that, the larger the dark energy density is and the more negative its pressure is, the higher the gravitational lensing probability is. This fact can provide an independent constraint for dark energy.Comment: 9 pages, 2 figure