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THE EFFECTS OF VELOCITY RATIO ON THE LARGE SCALE COHERENT STRUCTURES IN FREE SHEAR LAYERS
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作者 Zhang Hongquan and Shu Wei Tianjin University 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1991年第3期257-263,共7页
The velocity ratio of a free shear layer has an important influence on the spatial development of the large scale coherent structures in the layer. In this study, numerical simulations are performed to get an insight ... The velocity ratio of a free shear layer has an important influence on the spatial development of the large scale coherent structures in the layer. In this study, numerical simulations are performed to get an insight into this problem. The obtained numerical results agree quite well with those of a linear inviscid stability theory and the available experimental data. 展开更多
关键词 In THE EFFECTS OF VELOCITY RATIO ON THE large SCALE COHERENT STRUCTURES IN FREE SHEAR LAYERS
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Development and prospect on fully mechanized mining in Chinese coal mines 被引量:104
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作者 Jinhua Wang 《International Journal of Coal Science & Technology》 EI CAS 2014年第3期253-260,共8页
Fully mechanized mining(FMM)technology has been applied in Chinese coal mines for more than 40 years.At present,the output of a FMM face has reached 10-million tons with Chinese-made equipment.In this study,the new de... Fully mechanized mining(FMM)technology has been applied in Chinese coal mines for more than 40 years.At present,the output of a FMM face has reached 10-million tons with Chinese-made equipment.In this study,the new developments in FMM technology and equipment in Chinese coal mines during past decades are introduced.The automatic FMM technology for thin seams,complete sets of FMM technology with ultra large shear height of 7 m for thick seams,complete sets of fully mechanized top coal caving technology with large shear height for ultra-thick seams of 20 m,complete sets of FMM technology for complex and difficult seams,including steeply inclined seams,soft coal seams with large inclination angle,and the mechanized filling mining technology and equipment are presented.Some typical case studies are also introduced.Finally,the existing problems with the FMM technology are discussed,and prospect of FMM technology and equipment applied in Chinese coal mines is put forward. 展开更多
关键词 Fully mechanized mining Mining with large shear height Fully mechanized top coal caving Steeply inclined seam Back filling mining PROSPECT
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Strain Softening of Styrene-Isoprene-Styrene Copolymers under Large Amplitude Oscillatory Shear for Clarifying Payne Effect in Rubbers and Their Nanocomposites 被引量:1
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作者 Xin-Peng Fan Yi-Hu Song +1 位作者 Qiang Zheng Wan-Jie Wang 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2023年第1期153-165,共13页
To illustrate mechanisms of Payne effect in rubbers and their nanocomposites experiencing large amplitude oscillatory shear(LAOS),comparison studies were performed in styrene-isoprene-styrene(SIS)copolymers and their ... To illustrate mechanisms of Payne effect in rubbers and their nanocomposites experiencing large amplitude oscillatory shear(LAOS),comparison studies were performed in styrene-isoprene-styrene(SIS)copolymers and their selectively crosslinked materials at temperatures below and above glass transition temperature of the polystyrene(PS)phase.It was found that under periodic dynamic shear,the strain softening is reversible when the polyisoprene(PI)phase,either crosslinked or not,is restricted by hard PS domains but it shows hysteresis once the PS domains disassociate.The strain softening can happen at the time scale of intrinsic Rouse relaxation of elastically active network strands.Critical stress of strain softening scales with number density of elastically active network strands,a simple relation being verified not only in the selectively crosslinked SIS copolymers but also in PI gum vulcanizates and carbon black filled PI compounds.Payne effect is traditionally used to term strain softening of highly filled rubber vulcanizates under LAOS deformation while evidenced herein is that the Payne effect of highly filled rubber vulcanizates shares the mechanism being common to the strain softening of SIS copolymers. 展开更多
关键词 large amplitude oscillatory shear SIS Rubber nanocomposites Strain softening
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Effect of a filter cake on shear behavior of sand-concrete pile interface
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作者 CHEN Chen LENG Wu-ming +3 位作者 YANG Qi DONG Jun-li XU Fang RUAN Bo 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期2019-2032,共14页
A filter cake is often formed between soil and concrete during casting concrete in the ground,such as constructions of diaphragm walls and bored piles.The present study aims to investigate the effect of the filter cak... A filter cake is often formed between soil and concrete during casting concrete in the ground,such as constructions of diaphragm walls and bored piles.The present study aims to investigate the effect of the filter cake on the shear behavior of the sand-concrete pile interface.A series of sand-concrete interface direct shear tests were performed with a large-direct shear apparatus while considering different roughness(I=0,10,20 and 30 mm)and filter cake thickness(Δh=0,5 and 10 mm).For a smooth interface without a filter cake,the shear stress-horizontal displacement curves showed a“softening”response.The peak shear strength and friction angle decreased exponentially with increasing theΔh.Whereas,for a rough interface withΔh=5 or 10 mm,the shear stress-horizontal displacement curves presented a“hardening”response.The peak strength,as well as friction angle,decreased linearly with increasing theΔh.Moreover,a critical roughness I_(cr)of 10 mm was observed in the tests without a filter cake.The interface shear strength initially increased with increasing I but gradually decreased when the I exceeded I_(cr).In addition,the filter cake could reduce the roughness sensitivity on shear strength. 展开更多
关键词 filter cake sand-concrete pile interface large scale direct shear test shear behavior critical roughness
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Large Amplitude Oscillatory Shear Studies on the Strain-stiffening Behavior of Gelatin Gels
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作者 Wei-xiang Sun Li-zhen Huang +2 位作者 Yan-rui Yang Xin-xing Liu 童真 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2015年第1期70-83,共14页
Linear and nonlinear viscoelasticity of gelatin solutions was investigated by rheology. The dynamic mechanical properties during the sol-gel transition of gelatin followed the time-cure superposition. The fractal dime... Linear and nonlinear viscoelasticity of gelatin solutions was investigated by rheology. The dynamic mechanical properties during the sol-gel transition of gelatin followed the time-cure superposition. The fractal dimension df of the critical gel was estimated as 1.76, which indicated a loose network. A high sol fraction ws = 0.61 was evaluated from the plateau modulus by semi-empirical models. Strain-stiffening behavior was observed under large amplitude oscillatory shear(LAOS) for the gelatin gel. The strain and frequency dependence of the minimum strain modulus GM, energy dissipation Ed, and nonlinear viscoelastic parameter NE was illustrated in Pipkin diagrams and explained by the strain induced helix formation reported previously by others. The BST model described the strain-stiffening behavior of gelatin gel quite well, whereas the Gent and worm-like chain network models overestimated the strain-stiffening at large strains. 展开更多
关键词 Gelatin large amplitude oscillatory shear Strain-stiffening.
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