This study used computer aided design software Solid Work to draw four models of pressure vessel, and to analyze the displacement and the stress by the finite element analysis software ANSYS. To carry on the main body of the pressure vessel and find the highest stress of the pressure vessels by finite element analysis. The stress analysis of the pressure vessel main body contains main nozzle, the skirt of the main body ban and the connected control line. And the stress analysis factor includes: the stress distribution situation by seismic force and the displacement change factor of the wind power and the stress distribution condition of the thermal load by expand with heat and contract with cold (normal temperature climb to high temperature). The researcher also discussed the difference of the stress distribution between individual analysis and the overall analysis. The present study used finite element analysis (contain main body, spray nozzle, skirt in view of the overall analysis ban) to carry on the shell individual analysis first, then using the boundary condition of the result displacements regarding connected spray nozzle, the pipeline by the shell analysis again carries on stress analysis of the spray nozzle and the pipeline. Based on the results of stress analysis by the finite element method, the researcher discussed the differences of stresses between overall analysis and the individual analysis results.

In coronary artery bypass surgery the autologous saphenous vein is the most commonly used vascular graft. However, in a growing number of patients this vein is not available due to disease or availability. To date, there are no commercially available vascular grafts to replace the autologous saphenous vein. Nevertheless, it is widely accepted that a successful small diameter blood vessel alternative will be found using a tissue engineering approach. A photo-cross-linked biodegradable elastomer of acrylated star-poly(ε-caprolactone-co-D,L-lactide) (ASCP) has recently been developed. The elastomer possesses many desirable properties, such as manufacturability and mechanical properties, making it an interesting scaffolding material candidate for this application. To test the feasibility of the ASCP elastomer as a scaffolding material, a porous scaffold with 90% porosity was constructed using paraffin microbeads combined with an emulsion of ASCP prepolymer and water. Native arterial mechanical properties were matched with an 1800 Da ASCP elastomeric scaffold (ELAS 1800) having 85% porosity. In vitro degradation of scaffolds prepared with two different ASCP Mn (1800 and 4500 Da) was investigated for 8 weeks. Bulk hydrolysis was the mode of degradation regardless of configuration, with the porous scaffold degrading slower than the nonporous control. In addition, the ELAS 4500 scaffold also degraded faster than the ELAS 1800 scaffold with the same porosity. In order to promote the cellular response to this potential vascular scaffold, the surface of the elastomer was modified to enhance bovine coronary artery smooth muscle cell (SMC) attachment and proliferation. Base etching the surface was not as effective as adding a small peptide sequence Gly-Arg-Gly-Asp-Ser (GRGDS) known to enhance cell adhesion. The surface modifications did not change SMC phenotype as all surfaces expressed the contractile marker proteins smooth muscle α-actin and h-caldesmon. The SMCs also expressed these marker proteins when seeded on porous scaffolds. Finally, it was possible to integrate the porous scaffold into a biomimetic blood vessel design. With this initial testing, it appears that the ASCP elastomer is a feasible scaffolding material for small diameter blood vessel tissue engineering. Nevertheless, more detailed testing of mechanical properties and cell behaviour must be conducted to ascertain that the ASCP elastomer and the proposed biomimetic blood vessel design can be appropriate replacements for the autologous saphenous vein. / Thesis (Master, Chemical Engineering) -- Queen's University, 2007-11-18 20:27:30.635

No description available.

This thesis treats the motion of a small vessel described in six degrees of freedom. There are three are translation equations of motion and the other three are equations of angular motion. The aim is to develop a model with a sound mathematical base and use experimentation to find forces to aid the completion of the model, with the intention of use in an auto pilot, by the following means: 1) By solving the equations of motion for large movements, with given sea and wind conditions and also with given control forces and moments. 2) Deduce the forces and moments being applied from the sea etc., from the motion of the vessel. Thus to enable the auto pilot to deduce the required additional forces and the forces and moments applied by the water and wind and the control devices, such as the propeller and rudder. These two aims are achieved by analysing the transformation of axes using the standard Euler equations. However, as Euler's angles are ordered and therefore cannot cope with large angles which are present in the motion of a small vessel, another set of angles relating to axes and planes have been deduced. These are then rotated and the set of three measured angles are found in terms of the Euler angles. This is the main pan of original work in the thesis. The rest of the thesis is then based upon these set of measured angles and a general case mathematical model is deduced using them. This is proceeded by a functional analysis of the vessel's motion, environment and control action's. After that the general case model is theoretically validated by analysing the work done by ARJM Lloyd and showing how his work is a specific case of the general case. Experimental work performed on a small vessel is then used in the building of a mathematical model for the specific case of a small vessel, using a set of measured angles.

Thesis (M. S. in Biomedical Engineering)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.

No description available.

No description available.

The R6 procedure is used for the prevention and prediction of crack behaviour and other defects in the reactor pressure vessel(RPV). The RPV material is an upper-bainitic, low alloy steel structure, which deforms inhomogeneously when yielding. The current codes that are used to design and calculate the fracture, within an RPV, assume that the material yields continuously as the size of the L¨uders strain is less than 2%. However, the work of Wenman et al[1] has shown that the inclusion of a L¨uders band during calculations can reduce the residual stress in a material, when compared to standard work-hardening models and, consequently, reduces the amount of conservatism. The objective of the research was to determine whether Wenman’s finding could be generalised and therefore initiate a re-evaluation of R6 procedure, when looking into materials that yield discontinuously. This required further investigation into L¨uders bands, such as using failure assessment diagrams (FADs). The findings from FADs showed that at the temperature range for an RPV steel at -155±C for different micro-structures (assuming that the material deforms homogeneously), this reduced the amount of conservatism. However, at fracture toughness values more representative of room temperature behaviour, the converse was true. That is, assuming a discontinuous yield point reduced the amount of conservatism. It was also shown that the tempered martensite structure could be used as an alternative to the current upper bainitic, low alloy steel that is used in RPVs. Further insight is gained into the nature of a L¨uders band, by developing a theoretical model that showed explicit relations between L¨uders strain and the mean free-path(ferrite path), dislocation density and the grain-size. It was also shown that an explicit relation between the L¨uders strain and carbon content was possible from known data, which a new parameter Á was derived, and is the derivative of the work-hardening exponent with respect to the lower yield stress. / © Crown Copyright

The original constructive act of human nature was to make shelter. The original architectural act of human nature was to create place. Nature is made of emotive elemental matter- the horizontal of earth, the vertical of sky, the transcendence of water and the energy of fire. Human beings, alone among the living, have the opportunity to purposefully act. We have squandered this privilege until now, only considering nature where we have not yet built. We must endear ourselves to the source of our existence and through each experience gain nourishment and inspiration. Architecture manifests the spiritual revelation of human intervention into nature. The intimate act of dwelling requires fulfillment and sacrifice. The home should inspire the mind, envelop the soul, nurture the body, and free the spirit. The inhabitant must feel grounded within the foundation, thoughtfully carved into the earth, permeated with the warmth of being embedded, and enriched by the centering focus of a flame within the darkness. The inhabitant must feel elevated without weight upon lightness of frame, touched by a cool breeze, surrounded by canopy and inspired by the heavens. For this journey, the architect must purposefully and poetically place humanity within nature. This is the intimate domain of dwelling between earth and sky. / Master of Architecture

Recent advances in retinal imaging have made it possible to take measurements of retinal oxygen saturation noninvasively in humans. This allows studying the supply of oxygen in healthy and diseased retinae, thereby advancing our understanding of both the normal functioning of the retina and of retinal pathologies. However, retinal oximetry is still a research tool only and requires further improvement before being used in a clinical setting. Here, a single-wavelength flickering light was used to increase retinal blood flow in healthy subjects. This increase is revealed by both vasodilation and an increase in retinal oxygen saturation. A flickering light stimulus provides the means to assess the sensitivity of any retinal oximetry system, as such systems should be able to pick up this increase in retinal blood flow. In addition, the flickering light allows for com- parison to be made within rather than between subjects and can be used to examine the activation of the eye. This reduces the influence of potential confounding factors between subjects including differences in fundus pigmentation and illumination. The most commonly used method to measure retinal oxygenation is the optical density ra- tio (ODR) approach. The standard approach is to compute the average ODR for each vessel segment by combining the hundreds of individual ODR readings and then to use the mean of these segment averages as a measure of oxygen saturation. Alternatively, it has been suggested that the peak location of Gaussian functions fitted to histograms of individual ODR readings can be used as an measure of retinal oxygenation. In response to a 10Hz flickering light, the venular diameter increased by 3.44% (SEM: ±0.53%) (n=16, p<0.05) and the arteriolar diameter by 1.87% (±0.72 %) (p<0.05). The optical density ratio, measured with the Gaussian fit, decreased in the venules from 0.713 (±0.015) to 0.694 (±0.015) (p<0.05). No changes in arteriolar optical density ratios were measured. The post-flicker measurement was computed as the average of up to four post-flicker datasets obtained at 10s, 20s, 30s and 40s after onset of flickering. These results suggest that the flickering light increased retinal blood flow. The mean absolute percentage error was lower in venules for the Gaussian fit method than for the gold standard method for datasets taken at 30s and 40s after onset of flickering. Thus, the Gaussian fit method was more robust. All measurements were taken with a custom-made retinal oximeter. The pixel intensity of the blood vessel and the intensity on either side of the vessel had to be extracted to compute the individual optical density ratios. This required the automatic extraction of the retinal vasculature. Two such algorithms were developed and applied to two databases of retinal fundus images: the DRIVE and the novel DR HAGIS database. One algorithm was purely based on the pixel intensities, while the other made use of oriented Gabor filters. These two algorithms segmented the images to a similar accuracy (DRIVE: 94.56% and 94.54%, DR HAGIS: 95.83% and 95.71% for the intensity and Gabor filter based algorithm, respectively) and performed as well as a human expert (DRIVE: 94.73%). These algorithms were of sufficient quality to extract individual segments for the oximetry study and to align fundus images.