Boundary shear flow past a cylinder near a wall

An investigation on boundary shear flow past a circular cylinder near a wall is numerically performed via a stabilized finite element method. The main focus is to uncover its major difference with the flows corresponding to the symmetry boundary, and to two identical circular cylinders in a side-by-side arrangement. In particular at Reynolds number extensive simulations are made for different gaps between the cylinder and wall. It is noted that in the wake of the cylinder the vortex contour lines shift upwards. At the flow behind a cylinder near the wall may be time dependent. With a reduction of the gap spacing to a magnitude in (0.75,1), the vortex shedding nearly vanishes. For the flow behind two identical circular cylinders side and side, the flow may change from periodic flow to totally irregular one. The drag force CD, lift force CL,rms and Strouhal number St of the circular cylinder near the wall vary differently with the gap, compared with those in the other two cases. When the cylinder is located in the boundary layer, the boundary shear flow has strong effect on the hydrodynamic quantities. Extensive simulations are also made for 400, 600 and 800. It is found that the Reynolds number has strong effect on the flow and force on the cylinder, not only through the variation of Re itself but also the boundary layer of the wall. Withe Re increasing, strong vortex shedding from the near-wall cylinder at starts above a Re in (200, 300)

Experimental and numerical studies of the effects of a rail vibration absorber on suppressing short pitch rail corrugation

The effects of a rail vibration absorber on suppressing short pitch rail corrugation are studied. Firstly, a rail vibration field test is carried out to analyze the vibration response of the rail with and without the vibration absorbers. Secondly, based on the hypothesis that friction-induced self-excited vibration of a wheel-rail system causes rail corrugation; two finite element models of a wheel-rail system and a wheel-rail-absorber system are established and analyzed. Both sets of rail vibration test results and theoretical results show that the rail absorbers can effectively reduce the friction-induced self-excited vibration of the wheel-rail system in the frequency range of 200-800 Hz, which corresponds to frequencies of short pitch rail corrugation. This may be a main reason that the rail vibration absorber can suppress the formation of short pitch rail corrugation

Salient Objects in Clutter: Bringing Salient Object Detection to the Foreground

We provide a comprehensive evaluation of salient object detection (SOD) models. Our analysis identifies a serious design bias of existing SOD datasets which assumes that each image contains at least one clearly outstanding salient object in low clutter. The design bias has led to a saturated high performance for state-of-the-art SOD models when evaluated on existing datasets. The models, however, still perform far from being satisfactory when applied to real-world daily scenes. Based on our analyses, we first identify 7 crucial aspects that a comprehensive and balanced dataset should fulfill. Then, we propose a new high quality dataset and update the previous saliency benchmark. Specifically, our SOC (Salient Objects in Clutter) dataset, includes images with salient and non-salient objects from daily object categories. Beyond object category annotations, each salient image is accompanied by attributes that reflect common challenges in real-world scenes. Finally, we report attribute-based performance assessment on our dataset.Comment: ECCV 201

PS-DInSAR公共主影像的优化选取

Author name used in this publication: 陈强Author name used in this publication: 丁晓利, DING Xiao-liAuthor name used in this publication: 刘国祥Title in Traditional Chinese: PS-DInSAR公共主影像的優化選取Journal title in Traditional Chinese: 測繪學報2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Atomically dispersed Ni in cadmium-zinc sulfide quantum dots for high-performance visible-light photocatalytic hydrogen production.

Catalysts with a single atom site allow highly tuning of the activity, stability, and reactivity of heterogeneous catalysts. Therefore, atomistic understanding of the pertinent mechanism is essential to simultaneously boost the intrinsic activity, site density, electron transport, and stability. Here, we report that atomically dispersed nickel (Ni) in zincblende cadmium-zinc sulfide quantum dots (ZCS QDs) delivers an efficient and durable photocatalytic performance for water splitting under sunlight. The finely tuned Ni atoms dispersed in ZCS QDs exhibit an ultrahigh photocatalytic H2 production activity of 18.87 mmol hour-1 g-1. It could be ascribed to the favorable surface engineering to achieve highly active sites of monovalent Ni(I) and the surface heterojunctions to reinforce the carrier separation owing to the suitable energy band structures, built-in electric field, and optimized surface H2 adsorption thermodynamics. This work demonstrates a synergistic regulation of the physicochemical properties of QDs for high-efficiency photocatalytic H2 production

A comparison of acidic and enzymatic hydrolysis of rutin

Rutin and its hydrolysis products (isoquercitrin and quercetin) are widely used as important materials in food and pharmaceutical industry. In this study, the effects of various acids and enzymes as catalysts on the hydrolysis reaction of rutin were studied. In comparison with acidic and enzymatic catalysis of rutin, the research results indicated that there was a sharp difference in the selectivity of hydrolysis product between the methods. When 2.5% H3PO4, 1% HCl and 0.5% H2SO4 were used as catalysts, transformation yields of isoquercitin hydrolyzed from rutin were 9.60, 0.69 and 1.25%, but those of quercetin were 11.13, 100 and 2.57%, respectively. When hesperidinase, snailase and cellulase-T2440 were used as catalysts, transformation yields of isoquercitin hydrolyzed from rutin were 43.21, 3.07 and 0.00%, but those of quercetin were 58.10, 96.39 and 30.89%, respectively. In conclusion, the aglycon of rutin was deglycosolated easily under mild acidic hydrolysis conditions at appropriate temperatures, but its secondary glucoside was difficult to be obtained. Contrarily, the prepared isoquercitrin by enzymatic hydrolysis of rutin was preferable to the acidic hydrolysis, especially for hesperidinase.Key words: Rutin, isoquercitrin, quercetin, hydrolysis, acid, enzym

干涉雷达永久散射体自动探测——算法与实验结果

Author name used in this publication: 陈强Author name used in this publication: 刘国祥Author name used in this publication: 李永树Author name used in this publication: 丁晓利, DING Xiao-liTitle in Traditional Chinese: 干涉雷達永久散射體自動探測——演算法與實驗結果Journal title in Traditional Chinese: 測繪學報2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe