Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Detonation propagation in a compressible medium wherein the energy release has been made spatially inhomogeneous is examined via numerical simulation. The inhomogeneity is introduced via step functions in the reaction progress variable, with the local value of energy release correspondingly increased so as to maintain the same average energy density in the medium, and thus a constant Chapman Jouguet (CJ) detonation velocity. A one-step Arrhenius rate governs the rate of energy release in the reactive zones. The resulting dynamics of a detonation propagating in such systems with one-dimensional layers and two-dimensional squares are simulated using a Godunov-type finite-volume scheme. The resulting wave dynamics are analyzed by computing the average wave velocity and one-dimensional averaged wave structure. In the case of sufficiently inhomogeneous media wherein the spacing between reactive zones is greater than the inherent reaction zone length, average wave speeds significantly greater than the corresponding CJ speed of the homogenized medium are obtained. If the shock transit time between reactive zones is less than the reaction time scale, then the classical CJ detonation velocity is recovered. The spatio-temporal averaged structure of the waves in these systems is analyzed via a Favre averaging technique, with terms associated with the thermal and mechanical fluctuations being explicitly computed. The analysis of the averaged wave structure identifies the super-CJ detonations as weak detonations owing to the existence of mechanical non-equilibrium at the effective sonic point embedded within the wave structure. The correspondence of the super-CJ behavior identified in this study with real detonation phenomena that may be observed in experiments is discussed

Nuclear magnetic resonance imaging of the palliative operation for hypoplastic left heart syndrome

AbstractElectrocardiographic-gated nuclear magnetic resonance (NMR) imaging has been shown to be effective for the evaluation of congenital heart disease, particularly in supracardiac regions. This study evaluated the postoperative status after a stage I palliative operation (Norwood procedure) for hypoplastic left heart syndrome. The NMR images from three patients were compared with those of angiography and depicted all components of the reconstructed supracardiac and intracardiac anatomy after this operation. Nonobstructive anastomosis of the main pulmonary artery to the proximal aorta was clearly demonstrated in each patient. The caliber of the central or branch pulmonary artery, patency and caliber of the systemic to pulmonary artery shunt and the size of the atrial communication were also depicted in each patient and these findings corresponded with angiographic results.The results suggest that NMR imaging is effective for assessing the results of initial palliative surgery for hypoplastic left heart syndrome, which seems to be important for managing patients before subsequent definitive surgery

Digital subtraction angiography: A review of cardiac applications

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25579/1/0000123.pd

Geometric Alignments of the Subgrid-Scale Force in the Atmospheric Boundary Layer

priori tests of subgrid-scale (SGS) models for large-eddy simulations (LES). The experimental arrangements and data collected have facilitated studies of variables such as the filtered strain rate, SGS stress and dissipation, and the eddy viscosity coefficient. However, the experimental set-ups did not permit analysis of the divergence of the SGS stress (the SGS force vector), which is the term that enters directly in the LES momentum balance equations. Data from a field experiment (SGS2002) in the west desert of Utah, allows the calculation of the SGS force due to the unique 4 × 4 sonic anemometer array. The vector alignment of the SGS force is investigated under a range of atmospheric stabilities. The eddy viscosity model is likely aligned with the measured SGS force under near-neutral and unstable conditions, while its performance is unsatisfactory under stable conditions

The Effect of Filter Dimension on the Subgrid-Scale Stress, Heat Flux, and Tensor Alignments in the Atmospheric Surface Layer

In field experiments designed to study subgrid-scale parameterizations for large eddy simulation, the flow field is often measured and then filtered in two-dimensional planes. This two-dimensional filtering serves as a surrogate for three-dimensional filtering. The question of whether this will yield accurate results in subgrid-scale (SGS) models is addressed by analyzing data from a field experiment in which 16 sonic anemometers were deployed in a four by four grid. The experiment was held in July 2002 at the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility in the Utah West Desert. The full SGS stress tensor and its parameterizations using both two- and three-dimensional filterings are obtained. Comparisons are given between two- and three-dimensional filterings of the field measurements based on probability density functions (PDFs) and energy spectra of the SGS stress elements. The PDFs reveal that quantities calculated with two-dimensional filtering exhibit greater intermittency than those computed with three-dimensional filtering at the same scale. From the spectra it is observed that the different filtering methods result in similar behavior, but that spectra of SGS stress components computed with a threedimensional filter roll off at a slightly lower wavenumber than those computed with a two-dimensional filter. The PDFs and spectra of the stresses calculated with two- and three-dimensional filters can be made to collapse by reducing the three-dimensional filter scale according to Δ3-D = 0.84Δ2-D. Geometric alignment analyses are performed for the SGS heat flux, SGS stress, and filtered strain rate for the cases of stable, near-neutral, and unstable atmospheric stabilities. Under unstable and near-neutral atmospheric stability, two-dimensional filtering yields acceptable results; however, under stable atmospheric stability, a new approach is recommended and delineated

Meeting Highlights of the 11th Annual Scientific Sessions of the Society for Cardiovascular Magnetic Resonance, Los Angeles, February 1–3, 2008

This paper features the most interesting presentations and discussions of the 2008 Annual Sessions of the Society for Cardiovascular Magnetic Resonance, which were held in Los Angeles from February 1 to 3, 2008

Разработка коллекции дверной фурнитуры в технологиях металлообработки

Выпускная квалификационная работа содержит пояснительную записку, содержащую 85 страниц, включает (…) Объектами проектирования являются элементы коллекций, выполненных в трех разных стилях. Цель работы – разработка коллекций дверной фурнитуры в технологиях металлообработки. В процессе выпускной квалификационной работы было разработано три колелекции дверной фурнитуры, каждая из которых включает в себя три элемента. Выпускная квалификационная работа выполнена в текстовом редакторе Microsoft Word 2013. При создании электронных моделей использовался программный продукт SolidWorks2015 и ArtCAM 2008. Художественная часть создавалась с помощью бумаги и сангины. В результате исследования создан элемент коллекции в технологиях металлообработки.Final qualifying work contains an explanatory note containing 85 pages, includes (...) The objects are the elements of the design collections, made in three different styles. The purpose of work - development of collections of door hardware in metalworking technologies. During the final qualifying work three kolelektsii door fittings have been developed, each of which includes three elements. Final qualifying work carried out in Microsoft Word 2013. When you create a text editor, electronic models used by software SolidWorks2015 and ArtCAM 2008. Artistic part was created with the help of paper and sanguine. The study created a collection item in metalworking technologies