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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

slip casting and pressureless sintering of Ti3AlC2

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Journal of Advanced Ceramics 2019年第3期8卷 367-376页

作者： Yimin GONG Wubian TIAN Peigen ZHANG Jian CHEN Yamei ZHANG Zhengming SUN Jiangsu Key Laboratory of Advanced Metallic Materials School of Materials Science and EngineeringSoutheast UniversityNanjing211189China Jiangsu Key Laboratory of Construction Materials School of Materials Scienceand EngineeringSoutheast UniversityNanjing211189China

slip casting and subsequent pressureless sintering(PLS)allow the preparation of complex-shaped and large-sized Ti3AlC2 components for many potential *** behaviors of the suspensions,green compacts,and sintered samples of Ti3AlC2 were studied in this *** optimized condition of 1 wt%of arabic gum as dispersant at pH=10 results in a Ti3AlC2 suspension for slip casting Ti3AlC2 green compacts without macro defects or *** sintering temperature and Al4C3 embedding powder are found to dominate the properties of the sintered Ti3AlC2 *** Ti3AlC2 sample sintered at 1450℃for 1.5 h with Al4C3 embedding powder reaches the best properties,namely 95.3%relative density,hardness of 4.18 GPa,thermal conductivity of 29.11W·m-1·K-1,and electrical resistivity of 0.39μΩ·*** findings in this work may pave the way for the application of MAX phases with large size and complex shape.

关键词： slip casting pressureless sintering(PLS) properties Ti3AlC2

Influence of permeation effect on themicrofabric of the slip zone soils: A case study from the Huangtupolandslide

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Journal of Mountain Science 2019年第6期16卷 1231-1243页

作者： MIAO Fa-sheng WU Yi-ping XIE Yuan-hua LI Lin-wei LI Jie HUANG Lei Faculty of Engineering China University of GeosciencesWuhan 430074China China University of Geosciences Press Wuhan 430074China

This study aims to investigate the correlation between the permeation effect and microfabric of the slip zone soils with Huangtupo landslide in the Three Gorges Reservoir as the study case. Based on the permeability test and scanning electron microscope(SEM) images analysis, the fractal theory and probability entropy are used to quantify the characteristics of the remodeling specimens. First, the relationships between initial moisture content(IMC) and microstructure of the soil(percentage of particle area(PPA), pore roundness(Rp)) before and after permeability test are summarized. Then, the fractal dimension of the soil(pore distribution(Dpd), pore size(Dps)) are analyzed under the permeation effect. Based on the probability entropy, the entropy of pore(Ep) is used to characterize the porosity orientation, and the rose diagrams are used to show the particle orientation under the permeation effect. Finally, the relationship between the microstructure of the soil and its mechanical property is discussed. Results show that under the permeation effect, the microstructure of the soil has undergone tremendous changes. A flat long pore channel is formed. The order of the pore arrangement is enhanced, and soil particles switch the long axis to parallel infiltration direction to reach a new steady state. It can be inferred that the strength of soil would be weakened if the fractal dimension of soil pore decreases under any external environment.

关键词： Permeation effect slip zone soils Microstructure SEM Fractal theory Preferential orientations

Transformation and removal of ammonium sulfate aerosols and ammonia slip from selective catalytic reduction in wet flue gas desulfurization system

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Journal of Environmental Sciences 2020年第2期32卷 72-80页

作者： Teng Cheng Xincheng Zhou Linjun Yang Hao Wu Hongmei Fan Key Laboratory for Energy Thermal Conversion and Control Ministry of EducationSoutheast UniversityNanjing 210096China Jiangsu Frontier Electric Technology Co. Ltd.Nanjing 211102China School of Energy and Mechanical Engineering Nanjing Normal UniversityNanjing 210042China

Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and *** removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization(WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD *** results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH4+will generate new ammoniumcontaining particles and gaseous *** ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry ***,even if the concentration of NH4+in the desulfurization slurry is quite low, a high level of NH4+was still contained in the fine particles at the outlet of the *** the accumulated NH4+in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+and increased the additional emission of primary NH4+*** the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+emitted from entrainment and evaporation of the desulfurization slurry *** addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH4+concentration and p H values of the slurry.

关键词： Selective catalytic reduction (SCR) Wet flue gas desulfurization (WFGD) Ammonium sulfate Ammonia slip Emission characteristics

Influence of slip ratio on worn-surface microstructure and fatigue wear behavior of D2 wheel steel

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Journal of Iron and Steel Research International 2018年第12期25卷 1278-1286页

作者： Chun-peng Liu Xiu-juan Zhao Peng-tao Liu Chong Xu Rui-ming Ren School of Material Science and Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina Key Laboratory of Critical Materials of Rail Transportation in Liaoning Province Dalian Jiaotong University Dalian 116028LiaoningChina School of Mechanical Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina

To investigate the worn-surface microstructure and fatigue cracks in D2 wheel steel under the pure rolling and 0.5% slip ratio conditions,a rolling wear test using a GPM-40 wear machine to simulate the wheel/rail operation was performed. After testing,a transmission electron microscope,a scanning electron microscope with electron backscatter diffraction,and micro-hardness testers were used to characterize the microstructure and fatigue *** surface microstrncture and hardness of the pure rolling sample were in a steady state after 8 × 10^4 cycles;however,the 0.5% slip ratio sample reached a steady state after 7 × 10^3 *** of whether the test uses the slip ratio,the orientation of lamellar pearlites gradually became parallel to the surface and a portion of lamellar cementites was fragmented and dissolved during the formation of steady-state *** slip ratio accelerates this *** hardening mechanism of the samples shows a decrease in the lamellar spacing of pearlite and the refinement of proeutectoid ferrite (PF).As the number of cycles increased,plastic deformation of samples became increasingly severe and the wear mechanism of the samples was fatigue wear in steady *** sample surfaces formed shallow cracks,which gradually peeled *** slip ratio accelerated the initiation and propagation of fatigue cracks because of the high friction stress on the contact *** fatigue cracks initiated at the interface of pearlite and PF and in the PF region.

关键词： D2 wheel steel slip ratio Wom-surface microstructure Wheel/rail system Rolling wear

Development of a Tactile and slip Sensor with a Biomimetic Structure-enhanced Sensing Mechanism

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Journal of Bionic Engineering 2019年第1期16卷 47-55页

作者： Yonggang Jiang Zhiqiang Ma Bonan Cao Longlong Gong Lin Feng Deyuan Zhang School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China International Research Institute for Multidisciplinary Science Beihang UniversityBeijing 100191China

Tactile and slip sensors have gained tremendous attention for their promising applications in the fields of smart robotics,implantable medical devices and minimally invasive *** by the structure-enhanced sensing mechanisms of human fingertips and tree frog toes,we developed a tactile and slip sensor by combining biomimetic surface microstructures with highly sensitive P(VDF-TrFE)nanofiber sensors on a flexible polyimide *** the surface microstructures could mediate the micro-vibration induced by slip motion,the frequencies of output signals revealed a strong correlation with the periods of *** addition,we proposed a method to discriminate touch force from slip motion using the criterion of standard deviation of time delay from the output signals of neighboring sensor elements.

关键词： tactile sensor slip detection nanofiber microstructure biomimetic sensing

Effects of temperature on critical resolved shear stresses of slip and twining in Mg single crystal via experimental and crystal plasticity modeling

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Journal of Magnesium and Alloys 2023年第6期11卷 2027-2041页

作者： Kwang Seon Shin Lifei Wang Mingzhe Bian Shihoon Choi Alexander Komissarov Viacheslav Bazhenov Magnesium Technology Innovation Center Department of Materials Science and EngineeringSeoul National University1 Gwanak-roGwanak-guSeoul 08826Republic of Korea Laboratory of Medical Bioresorption and Bioresistance Moscow State University of Medicine and DentistryDelegatskaya 20/1Moscow127473 Russia Shanxi Key Laboratory of Advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China Departments of Advanced Components and Materials Engineering Sunchon National UniversitySuncheonJeonnam57922Republic of Korea Laboratory of Hybrid Nanostructured Materials National University of Science and Technology"MISiS"Leninskiy pr.4Moscow119049 Russia Casting Department National University of Science and Technology"MISiS"Leninskiy pr.4Moscow119049 Russia

Magnesium(Mg)single crystal specimens with three different orientations were prepared and tested from room temperature to 733 K in order to systematically evaluate effects of temperature on the critical resolved shear stress(CRSS)of slips and twinning in Mg single *** duplex non-basal slip took place in the temperature range from 613 to 733 K when the single crystal samples were stretched along the*** contrast,the single basal slip and prismatic slip were mainly activated in the temperature range from RT to 733 K when the tensile directions were inclined at an angle of 45°with the basal and the prismatic plane,*** self-consistent(VPSC)crystal modeling simulations with genetic algorithm code(GA-code)were carried out to obtain the best fitted CRSSs of major deformation modes,such as basal slip,prismatic slip,pyramidalⅡ,{1012}tensile twinning and{1011}compressive twinning when duplex slips accommodated ***,CRSSs of the basal and the prismatic slip were derived using the Schmid factor(SF)criterion when the single slip mainly accommodated *** the CRSSs of major deformation modes obtained by the VPSC simulations and the SF calculations,the CRSSs for basal slip and{1012}tensile twinning were found to show a weak temperature dependence,whereas those for prismatic,slip and{1011}compressive twinning exhibited a strong temperature *** the comparison of previous results,VPSC-GA modeling was proved to be an effective method to obtain the CRSSs of various deformation modes of Mg and its alloys.

关键词： Magnesium Single crystal Critical resolve shear stress slip Twinning

Development of a Tribofidelic Human Heel Surrogate for Barefoot slip Testing

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Journal of Bionic Engineering 2022年第2期19卷 429-439页

作者： Subhodip Chatterjee Arnab Chanda Centre for Biomedical Engineering Indian Institute of Technology DelhiNew Delhi 110016India Department of Biomedical Engineering All India Institute of Medical ScienceNew Delhi 110029India

Barefoot slips contribute to over 37% of recurrent fall-related injuries across all age *** study slip risk across a wide range of flooring conditions,slip meters with barefoot surrogates(i.e.,sensors,as per ASTM standard nomenclature)such as animal skins and rubbers have been used to date,which exhibit biomechanical and frictional properties widely different from the barefoot human *** of a surrogate which can accurately simulate the human heel skin properties would be immensely beneficial for realistic assessment of barefoot slipping risk.A novel surrogate was developed using 3D scanning and printing,and biomimetics,which precisely simulates the biomechanical and frictional properties of the barefoot human heel *** slip testing was conducted with this surrogate on three common bathroom floorings and with six different *** of Friction(COF)results similar to human slipping experiments,high repeatability and reproducibility across wet and oily flooring conditions,were confirmed through experiments with the developed heel skin *** heel skin surrogate would be an indispensable model for accurate estimation of barefoot risk against slips and falls in bathrooms,bathtubs,and swimming pools.

关键词： Barefoot Surrogate slip Fall Bathroom Bathtub

Effects of slip length and hydraulic diameter on hydraulic entrance length of microchannels with superhydrophobic surfaces

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Frontiers in Energy 2020年第1期14卷 127-138页

作者： Wenchi GONG Jun SHEN Wei DAI Zeng DENG Xueqiang DONG Maoqiong GONG Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China

This paper investigated effects of slip length and hydraulic diameter on the hydraulic entrance length of laminar flow in superhydrophobic *** investigations were performed for square microchannels with Re ranging between 0.1 and *** is found that superhydrophobic microchannels have a longer hydraulic entrance length than that of conventional ones by nearly 26.62%at a low *** dimensionless hydraulic entrance length slightly increases with the increasing slip length at approximately Reslip lengths was developed,which has a satisfying predictive performance with a mean absolute relative deviation of 5.69%.The results not only ascertain the flow characteristics of superhydrophobic microchannels,but also suggest that super hydrophobic microchannels have more significant advantages for heat transfer enhancement at a low Re.

关键词： laminar flow hydraulic entrance length super hydrophobic surface slip length hydraulic diameter