This paper describes a robust regular polygon detector. Given image edges, we derive the a posteriori probability for a mixture of regular polygons, and thus the probability density function for the appearance of a set of regular polygons. Likely regular polygons can be isolated quickly by discretising and collapsing the search space into three dimensions. We derive a complete formulation for efficiently recovering the remaining dimensions using maximum likelihood at the locations of the most likely polygons. Results show robustness to noise, the ability to find and differentiate different shape types, and to perform real-time sign detection for driver assistance. 相似文献
In ‘atomistic’ device simulation the resolving of discrete charges onto a fine grained simulation mesh can lead to problems. The sharply resolved coulomb potential can cause simulation artefacts to appear in classical simulation environments using Boltzmann or Fermi-Dirac statistics. Various methods have been proposed in an effort to reduce or eliminate artefacts such as the trapping of mobile carriers in sharply resolved Coulomb wells, however they have met with limited success. In this paper we show an alternative approach for handling discrete charges in drift diffusion ‘atomistic’ simulations by properly introducing the related quantum mechanical effects using the Density Gradient formalism. This produces the desired effect of eliminating the trapping of mobile charge in heavily doped regions of the device. 相似文献
Chronic Kidney Disease (CKD) is associated with sustained inflammation and progressive fibrosis, changes that have been linked to altered connexin hemichannel-mediated release of adenosine triphosphate (ATP). Kidney fibrosis develops in response to increased deposition of extracellular matrix (ECM), and up-regulation of collagen I is an early marker of renal disease. With ECM remodeling known to promote a loss of epithelial stability, in the current study we used a clonal human kidney (HK2) model of proximal tubular epithelial cells to determine if collagen I modulates changes in cell function, via connexin-43 (Cx43) hemichannel ATP release. HK2 cells were cultured on collagen I and treated with the beta 1 isoform of the pro-fibrotic cytokine transforming growth factor (TGFβ1) ± the Cx43 mimetic Peptide 5 and/or an anti-integrin α2β1 neutralizing antibody. Phase microscopy and immunocytochemistry observed changes in cell morphology and cytoskeletal reorganization, whilst immunoblotting and ELISA identified changes in protein expression and secretion. Carboxyfluorescein dye uptake and biosensing measured hemichannel activity and ATP release. A Cytoselect extracellular matrix adhesion assay assessed changes in cell-substrate interactions. Collagen I and TGFβ1 synergistically evoked increased hemichannel activity and ATP release. This was paralleled by changes to markers of tubular injury, partly mediated by integrin α2β1/integrin-like kinase signaling. The co-incubation of the hemichannel blocker Peptide 5, reduced collagen I/TGFβ1 induced alterations and inhibited a positive feedforward loop between Cx43/ATP release/collagen I. This study highlights a role for collagen I in regulating connexin-mediated hemichannel activity through integrin α2β1 signaling, ahead of establishing Peptide 5 as a potential intervention. 相似文献
A promising catalytic system for the low temperature oxidation of methane to a methanol derivative has been investigated under both batch and semi-continuous operation in two different reactor types. The system comprises of a bimetallic palladium and copper(II) chloride catalyst contained in a trifluoroacetic acid (TFA) and an aqueous phase. Methane, oxygen and a co-reductant carbon monoxide constitute the gas phase. Typical operating conditions were a temperature of 85 °C and a pressure of 83 bar.
The yields of the methyl trifluoroacetate product observed in this present work were less than those obtained in other batch autoclave works, which employed only 4 ml of liquid phase, compared with 50 ml in this study. Furthermore, an encouraging initial product formation rate of ca. 40 mol/m3 h, quickly decreased after the first hour, and came to an apparent end after only 2 h. This observation had not been reported previously.
Work performed in a semi-continuous porous tube reactor (300 ml of re-circulating liquid phase) also showed the same reaction characteristics as in the batch reactor. Thus, the deteriorating product formation rate cannot be attributed to gaseous reactant depletion (batch operation). The results suggest problems associated with catalyst instabilities, e.g. with the previously elucidated Wacker chemistry. 相似文献
The cases of a sudden pipe expansion and a sudden pipe contraction are simulated within a flow loop-based test section designed to approximate disturbed conduit flow. Mass transfer rates to patch electrodes at selected positions within the test section have been measured using a limiting current methodology applied to oxygen reduction at copper in 3.5% wt./vol. NaCl. Using both large-scale polarisation linear sweep voltammetry and a potential step current transient technique with hydrodynamic steps, absolute and relative rates of oxygen mass transfer have been examined as a function of Reynolds number and location within the test section. The highest rates of oxygen transfer were observed both within the high velocity area of the test section and close to known regions of flow disturbance. Under the flow conditions used, patch electrode mass transfer relates to wall shear stress, which allowed areas of high mean and high fluctuating wall shear stress to be identified. 相似文献
This paper describes construction management teaching for the Master of Engineering in civil engineering course at the University of Glasgow in the United Kingdom. This course is a 5-yr undergraduate degree accredited by the Institution of Civil Engineers for membership in the Institution subject to graduates satisfying the appropriate postgraduate training objectives. Construction management teaching takes place in the third, fourth, and fifth years of the degree and is structured to make effective use of both traditional and problem-based learning teaching methods. Examples are given of two problem-based learning courses used in the fourth and fifth year of the degree course. Both are based on complex construction projects and provide students with the opportunity to apply and synthesis knowledge gained on the traditionally taught third year course. Formal feedback from students and informal feedback from local industry suggests that the courses are meeting their overall objective of producing graduates with relevant knowledge and skills in construction management. 相似文献
This paper reports the use of an immobilised ruthenium complex in a continuous flow process for the N-alkylation of morpholine with benzyl alcohol. The ruthenium-based catalyst was supported on a phosphine bound polymer. Screening experiments were first performed in a batch reactor, with a 16 vol% mixture of morpholine and benzyl alcohol (stoichiometric molar ratio of 1:1) in toluene as the solvent. Operating at 110 °C for 24 h, it was shown that high conversions (>99%) into the desired tertiary amine could be achieved. This reaction was then shown to be viable in a continuous flow reactor, where the catalytic polymer beads were retained in the bed. Operating at 150 °C and using p-xylene as a solvent, the conversion into the desired tertiary amine was shown to be as high as 98%. This approach is clearly very promising, as it provides a greener and more atom efficient route for the production of secondary and tertiary amines in the pharmaceutical industry. 相似文献