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Numerical simulation and scaling analysis of elasticity-induced lift force in a viscoelastic fluid between confining surfaces

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Journal of Hydrodynamics 2022年第4期34卷 756-766页

作者： Xin Zhao chao wei The State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China Science and Technology on Vehicle Transmission Laboratory Beijing Institute of TechnologyBeijing 100081China

How to accurately characterize the lift force on the particles near the solid surfaces is an ongoing challenge in fluid mechanics and microfluidic techniques, especially in a complex system with viscoelastic fluid or/and soft surface that is commonly encountered in a biological system. The motions of the particles in vicinity of a surface can be simplified to be a rigid cylinder surrounded by the viscoelastic fluid moving along a substrate which can be rigid or soft according to different cases. In such an inertial free system with a wide range of weissenberg number (Wi < 5.00, representing the ratio of the elastic force to the viscous force), firstly we numerically evaluate the influence of the systematic parameters, including the polymer viscosity, the geometry and Wi, on the net normal force for a cylinder closely moving along a rigid substrate, and the elasticity-induced lift force in a scaled form. It is shown that a strong shear arises in the viscoelastic confinement between the moving cylinder and the rigid substrate, it leads to the asymmetry of the first normal stress distribution around the cylinder, and thus the lift force. Then, the influence of a soft substrate on the lift force is considered, and we find that the lift force induced by the viscoelastic fluid always dominates in magnitude over that induced by the soft substrate deformation. This work provides a reliable scaling that can be utilized to quantify the elasticity-induced lift force on the particles in a viscoelastic system, such as the micro- and nanofluidic systems in biological applications.

关键词： Viscoelastic fluid scaling expression computational fluid dynamics lift force

The Rings Characterized by Minimal Left Ideals

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Acta Mathematica Sinica,English Series 2005年第3期21卷 473-482页

作者： Jun chao wei School of Science Mathematics Yangzhou University Yangzhou 225002 P. R. China

We study these rings with every minimal left ideal being a projective, direct summand and a p-injective module, respectively. Some characterizations of these rings are given, and the relations among them are obtained. With these rings, we characterize seinisiinple rings. Finally, we introduce MC2 rings, and give some characterizations of MC2 rings.

关键词： DS ring PS ring MP ring MC2 ring Minijective ring Singular ideal.

Automatic Colorization with Improved Spatial Coherence and Boundary Localization

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Journal of Computer Science & Technology 2017年第3期32卷 494-506页

作者： wei Zhang chao-wei Fang Guan-Bin Li Department of Computer Science The University of Hong Kong Hong Kong China School of Data and Computer Science Sun Yat-sen University Guangzhou 510006 China

Grayscale image colorization is an important computer graphics problem with a variety of applications. Recent fully automatic colorization methods have made impressive progress by formulating image colorization as a pixel-wise prediction task and utilizing deep convolutional neural networks. Though tremendous improvements have been made, the result of automatic colorization is still far from perfect. Specifically, there still exist common pitfalls in maintaining color consistency in homogeneous regions as well as precisely distinguishing colors near region boundaries. To tackle these problems, we propose a novel fully automatic colorization pipeline which involves a boundary-guided CRF （conditional random field） and a CNN-based color transform as post-processing steps. In addition, as there usually exist multiple plausible colorization proposals for a single image, automatic evaluation for different colorization methods remains a challenging task. We further introduce two novel automatic evaluation schemes to efficiently assess colorization quality in terms of spatial coherence and localization. Comprehensive experiments demonstrate great quality improvement in results of our proposed colorization method under multiple evaluation metrics.

关键词： automatic colorization deep learning conditional random field (CRF) color transform quality evaluation

Slip in Couette flow with pressure gradient:Theoretical and experimental investigation of hydrodynamic characteristics considering slip effect

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Journal of Hydrodynamics 2020年第1期32卷 107-115页

作者： Xin Zhao chao wei Shi-hua Yuan Science and Technology on Vehicle Transmission Laborator Bejing Institute of TechnologyBeijing 10081China

A new slip velocity model based on molecular potential theory and macro-force analysis,which is applied in Couette flow with pressure gradient,is built *** model is validated by later being introduced in hydrodynamic system to predict film distribution,which shows a good agreement with experimental data obtained from multi-beam intensity-based tests with Fe and Cu ball materials under accurate controlled temperature,load and different wall *** show that the slip length for Fe case is ignorable so it seems like no slip,but for Cu case,the slip length is large to make 20%discrepancy with no slip simulation and also behaves ***,during the experimental cases when both Fe and Cu ball velocities rise from-133 mm/s to 1330 mm/s,the slip velocity changes its direction with entrainment velocity and thus contributes to first enhance and then diminish the hydrodynamic film,but due to slip length on Cu case varying largely than that on Fe case,the film from Cu case and from Fe case has a clear cross-point between uh=80 mm/s and uh=220 m m/s(ub is the ball speed).The results above support strongly that Cu surface will lead to stronger slip than Fe case because of its smaller solid-liquid interaction,and obviously slip will influence hydrodynamic characteristics prominently.

关键词： Slip Couette flow with pressure gradient hydrodynamic characteristic

Josephson Current in Superconductor-Ferromagnet／Insulator／d-Wave Superconductor Junctions

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Communications in Theoretical Physics 2005年第3期43卷 551-555页

作者： LIXiao-wei DONGZheng-chao DepartmentofPhysics HuaiyinTeachersCollegeHuaian223001China

Solving the Bogoliubov-de Gennes equation, the energy levels of bound statesare obtained in the ferromagnetic superconductor. The Josephson currents in a ferromagneticsuperconductor/Insulator/d-wave superconductor junction are calculated as a function of the exchangefield, temperature, and insulating barrier strength. It is found that the Josephson criticalcurrent is always suppressed by the presence of exchange Geld h and depends on crystalline axisorientation of d-wave superconductor.

关键词： ferromagnetic superconductor d-wave superconductor FS/I/d junctionJosephson current

Solving the time-dependent Schrödinger equation by combining smooth exterior complex scaling and Arnoldi propagator

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Chinese Physics B 2022年第1期31卷 227-234页

作者： Shun Wang wei-chao Jiang College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China

Abstract We develop a highly efficient scheme for numerically solving the three-dimensional time-dependent Schrödinger equation of the single-active-electron atom in the field of laser pulses by combining smooth exterior complex scaling(SECS)absorbing method and Arnoldi propagation *** combination has not been reported in the *** proposed scheme is particularly useful in the applications involving long-time wave *** SECS is a wonderful absorber,but its application results in a non-Hermitian Hamiltonian,invalidating propagators utilizing the Hermitian symmetry of the *** demonstrate that the routine Arnoldi propagator can be modified to treat the non-Hermitian *** efficiency of the proposed scheme is checked by tracking the time-dependent electron wave packet in the case of both weak extreme ultraviolet(XUV)and strong infrared(IR)laser *** perfect absorption and stable propagation are observed.

关键词： time-dependent Schrödinger equation(TDSE) smooth exterior complex scaling(SECS)absorb-ing method Arnoldi propagator

OPTIMIZATION OF DESIGN PARAMETERS FOR FLUORESCENCE LAMINAR OPTICAL TOMOGRAPHY

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Journal of Innovative Optical Health Sciences 2011年第3期4卷 309-323页

作者： chao-wei CHEN YU CHEN Fischell Department of Bioengineering and Electrical and Computer Engineering 2218 Jeong H.Kim Building University of Maryland College ParkMD 20742USA

Laminar optical tomography(LOT)is a mesoscopic tomographic imaging technique ranging between confocal microscopy and diffuse optical tomography(DOT).Fluorescence LOT(FLOT)provides depth-resolved molecular information with 100-200μm resolution over 2-3mm *** this study,we use Monte Carlo simulation and singular-value analysis(SVA)to optimize the source-detector configurations for potential enhancement of FLOT imaging *** effects of different design parameters,including source incidence and detector collection angles,detector number,and sampling density,are *** results indicate that angled incidence/detection configuration might improve the imaging resolution and depth sensitivity,especially for low-scattering *** the number of detectors and the number of scanning steps will also result in enhanced imaging *** also demonstrate that the optimal imaging performance depends upon the background scattering coe±*** result might provide an optimization strategy for FLOT or LOT experimental setup.

关键词： Laminar optical tomography(LOT) fluorescence laminar optical tomography(FLOT) singular value analysis(SVA) image reconstruction

Supercritical gasification for the treatment of o-cresol wastewater

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Journal of Environmental Sciences 2006年第4期18卷 644-649页

作者： wei chao-hai HU Cheng-sheng WU chao-fei YAN Bo College of Environmental Science and Technology South China University of Technology Guangzhou 510640 China

The supercritical water gasification of phenolic wastewater without oxidant was performed to degrade pollutants and produce hydrogen-enriched gases. The simulated o-cresol wastewater was gasified at 440-650℃ and 27.6 MPa in a continuous Inconel 625 reactor with the residence time of 0.42-1.25 min. The influence of the reaction temperature, residence time, pressure, catalyst, oxidant and the pollutant concentration on the gasification efficiency was investigated. Higher temperature and longer residence time enhanced the o-cresol gasification. The TOC removal rate and hydrogen gasification rate were 90.6% and 194.6%, respectively, at the temperature of 650℃ and the residence time of 0.83 min. The product gas was mainly composed of H2, CO2, CFL and CO, among which the total molar percentage of H2 and CFL was higher than 50%. The gasification efficiency decreased with the pollutant concentration increasing. Both the catalyst and oxidant could accelerate the hydrocarbon gasification at a lower reaction temperature, in which the catalyst promoted H2 production and the oxidant enhanced CO2 generation. The intermediates of liquid effluents were analyzed and phenol was found to be the main composition. The results indicate that the supercritical gasification is a promising way for the treatment of hazardous organic wastewater.

关键词： supercritical water gasification o-cresol hydrogen-enriched gas wastewater treatment

Advances in the early diagnosis of hepatocellular carcinoma

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Genes & Diseases 2020年第3期7卷 308-319页

作者： weiyi Wang chao wei Xiamen Amplly Bio-engineering Co. LtdXiamenPR China

Hepatocellular carcinoma(HCC)is one of the most prevalent cancers *** contrast to the declining death rates observed for all other common cancers such as breast,lung,and prostate cancers,the death rates for HCC continue to increase by^2e3%per year because HCC is frequently diagnosed late and there is no curative therapy for an advanced *** early diagnosis of HCC is truly a big *** the past years,the early diagnosis of HCC has relied on surveillance with ultrasonography(US)and serological assessments of alpha-fetoprotein(AFP).However,the specificity and sensitivity of US/AFP is not satisfactory enough to detect early onset *** technological advancements offer hope for early HCC ***,we review the progress made in HCC diagnostics,with a focus on emerging imaging techniques and biomarkers for early disease diagnosis.

关键词： Biomarker Early diagnosis Hepatocellular carcinoma Imaging Liquid biopsy