Color object segmentation and tracking using flexible statistical model and level-set

Multimedia Tools and Applications - This study presents an unsupervised novel algorithm for color image segmentation, object detection and tracking based on unsupervised learning step followed with...     

How close to failure is a granite rock mass at a 5 km depth?

We discuss in this paper the mechanical significance of microseismicity induced by pore pressure variations. Particular attention is given to identifying whether microseismic events reflect only small effective stress perturbations, in a manner somewhat similar to the so-called Kaiser effect, or whether they outline the onset of large-scale failure. This issue is addressed in the context of the development of microseismic activity observed during large-scale water injections conducted in the 5000 m deep experimental geothermal reservoir at Soultz (France). Results from large hydraulic tests together with analysis of borehole images and induced seismicity are integrated to provide a well-constrained characterization of the complete stress field down to 5 km. It is shown that, for this site, pore pressure increments larger than 10% of the natural minimum principal stress magnitude are required for inducing large-scale shear failures that are characterized by a clear structuring of the microseismic events occurrence. But the onset of induced seismicity occurs for much smaller pore pressure variations that only reflect the “elastic” response to changes in local effective stresses. It is concluded that the linear variation with depth of principal stress magnitudes observed in this granite depends on the long-term rheology of this formation rather than on the frictional characteristics of the main faults that affect the massif.     

Image and video denoising by combining unsupervised bounded generalized gaussian mixture modeling and spatial information

Multimedia Tools and Applications - In recent years, a great deal of effort has been expended on developing robust solutions for images quality degradation caused mainly by noise. In this paper, we...     

Pool boiling of ammonia/water and its pure components: Comparison of experimental data in the literature with the predictions of standard correlations

Although ammonia/water has been used for decades as a working pair in absorption cycles for industrial refrigeration, very limited data are available on boiling heat transfer of this mixture. The intention of this work is to carry out a bibliographic revision of the information available in the open literature about nucleate pool boiling of the ammonia/water mixture and its pure components. The experimental data have been compared with existing prediction correlations for the pure components and also for their mixtures.For water, all the pure component pool boiling correlations gave similar predictions and were in good agreement with experimental data. For ammonia the prediction of the correlation and the experimental data showed more differences.At a given heat flux, the experimental data show that the mixture pool boiling heat transfer coefficient is lower than that obtained with pure components. Three of the well-known correlations for mixtures were compared against the experimental data. None of these correlations provided a good prediction of the mixture pool boiling heat transfer coefficient over a wide range of mass fraction. Furthermore, a new correlation has been proposed.     

Experimental studies on bubble pump operated diffusion absorption machine based on light hydrocarbons for solar cooling

An experimental investigation of an air-cooled diffusion absorption machine operating with a binary light hydrocarbon mixture (C₄H₁₀/C₉H₂₀) as working fluids and helium as pressure equalizing inert gas is presented in this paper. The machine, made of copper an available and very good heat conducting metal, is intended to be solar powered heat from flat plate or common evacuated tube collectors. The cooling capacity is 40–47 W respectively for 9 and 11°C chilled water temperature. Cold is produced at temperatures between −10 and +10 °C for a driving temperature in the range of 120–150 °C.     

Optimization of the Gaussian beam flattening using a phase-plate

Abstract

We consider the conversion of a Gaussian beam into a flat-top profile by using a phase-plate which consists of a single-zone binary optic. The near- and far-field distributions are studied. We deduce the conditions required to produce super-Gaussian profiles of order 6 at the focal plane of a converging lens.     

Natural convection cooling process from two identical porous-covering electronic components

In the present work, we focus to study numerically the natural convection cooling process from two identical electronic components located on the bottom wall of a two-dimensional cavity. Each electronic component is covered by a porous medium with finite thickness. The conservation equations governing the problem are discretized using the finite volume method and the SIMPLER algorithm is used to handle the nonlinear character of conservation equations. Calculations were carried out for the following control parameters: the porous/fluid thermal conductivity ratio (1 ≤ Rk_P1 ≤ 100), the Darcy and Rayleigh numbers (10⁻¹ ≤ Da ≤ 10⁻⁶, 10³ ≤ Ra ≤ 10⁶), the first porous-cover thickness (0.05 ≤ e₁ ≤ 0.3), and the separation distance between components (0.2 ≤ S ≤ 1) to highlight their influence on the cooling process. The results show that under specific values of the Darcy and Rayleigh numbers and in the limiting case of a high value of the porous/fluid thermal conductivity ratio (Rk_P1 = 100), a decrease in the maximum components temperature, up to 95%, is observed by increasing the porous-cover thickness from 0.05 to 0.3. In addition, by increasing the permeability, the Rayleigh number or the separation distance, an improvement in the cooling process of the two components greater than or equal to 22% is achieved.     

Comparison of numerical and experimental performance criteria of an ammonia–water bubble absorber using plate heat exchangers

A mathematical model for ammonia–water bubble absorbers was developed and compared with experimental data using a plate heat exchanger. The analysis was performed carrying out a sensitive study of selected operation parameters on the absorber thermal load and mass absorption flux. Regarding the experimental data, the values obtained for the solution heat transfer were in the range 0.51–1.21 kW m^?2 K^?1 and those of the mass absorption flux in the range 2.5–5.0 × 10^?3 kg m^?2 s^?1. The comparison between experimental and simulation results was acceptable being the maximum difference of 11.1% and 28.4% for the absorber thermal load and the mass absorption flux, respectively.     

Genes of the Enhancer of split and achaete-scute complexes are required for a regulatory loop between Notch and Delta during lateral signalling in Drosophila

Diabetic retinopathy is the most common chronic complication associated with diabetes mellitus. It affects 20% to 30% of diabetic women in the reproductive age group. This article reviews the course and treatment of pregnancy complicated by diabetic retinopathy.     

A simple model for falling film absorption on vertical tubes in the presence of non-absorbables

Most water–lithium bromide (LiBr) absorption chillers have a purge system to remove non-absorbable gases that cause a reduction in cooling capacity. Generally, the non-absorbables are originated in corrosion/passivation processes inside the machine, but leaks can also be a source of concern. However, since leaks must be corrected immediately to avoid machine deterioration, this study is mostly aimed at the non-absorbables evolved during operation. This paper analyses the effect of inlet non-absorbable air concentration, outlet purge velocity, absorber pressure and cooling water temperature on the falling film absorption process inside a vertical tube absorber, based on a simple transport coefficient model. This model consists of three ordinary differential equations solved with as method for initial-value problem, and a set of auxiliary equations. The study shows that the effect of non-absorbables can be significant, and furthermore provides a quantitative framework to aid in purge design. The nominal working conditions in this study were a solution Reynolds number of 100, an absorber pressure of 1.3 kPa, a cooling water temperature of 35 °C and an inlet solution concentration of 62% LiBr by weight. The results indicate that a minimum vapour velocity is required to sweep the non-absorbables along the absorber towards the purge, thus preventing reduced absorption fluxes. At a cooling water temperature of 35 °C, an inlet air concentration of 20% (by mole) resulted in a 61% reduction in mass absorption flux.