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EXPERIMENTAL INVESTIGATION OF CAVITATION IN A SUDDEN EXPANSION PIPE

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Journal of Hydrodynamics 2011年第3期23卷 348-352页

作者： ZHANG Jian-min YANG Qing WANG Yu-rong XU Wei-lin CHEN Jian-gang state key {2. of hydraulics and mountain river engineering Sichuan University Chengdu 610065 China

For sudden expansion pipes, experiments were carried ＇Out to study the cavitation inception for various enlargement ratios in high speed flows. The flow velocity of the prototype reaches 50 m/s in laboratory. The relationship between the expansion ratio and the incipient cavitation number is obtained. The scale and velocity effects are revealed. It is shown that Keller＇s revised formula should be modified to calculate the incipient cavitation number when the forecasted velocity of the flows in the prototype exceeds the experimental velocity.

关键词： high speed flows sudden expansion pipe cavitation incipient scale effect

THE COUNTER-JET FORMATION IN AN AIR BUBBLE INDUCED BY THE IMPACT OF SHOCK WAVES

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Journal of Hydrodynamics 2011年第5期23卷 562-569页

作者： BAI Li-xin XU Wei-lin LI Chao GAO Yan-dong Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China state key {2. of hydraulics and mountain river engineering Sichuan University Chengdu 610065China School of Electronic and Information engineering Liaoning Technical University Huludao 125105 China

The interaction of an air bubble （isolated in water or attached to a boundary） with shock waves induced by electric sparks is investigated by high-speed photography. The interaction is closely related to the counter-jet induced by the impact of shock waves. The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same air bubble, but the mechanism is different with that of the counter-jet formation in a collapsing cavitation bubble. The formation of a counter-jet in an air bubble is related to discharge energy, air bubble size and radius of shock wave. With a given energy of the spark discharge, the formation of a counter-jet in an air bubble is related to δ / ε （the ratio of the dimensionless bubble-bubble distance to the dimensionless air bubble radius）. The counter-jet will only be produced when δ / ε is in the range of 1.2.2.2. The counter-jet in an air bubble is of an important nuclei-generating mechanism.

关键词： cavitation bubble shock wave counter-jet high-speed photography

Optimization of Agrobacterium tumefaciens-Mediated Immature Embryo Transformation System and Transformation of Glyphosate-Resistant Gene 2.G2.EPSPS in Maize(Zea mays L.)

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Journal of Integrative Agriculture 2013年第12期12卷 2134-2142页

作者： YU Gui-rong LIU Yan DU Wen-ping SONG Jun LIN Min XU Li-yuan XIAO Fang-ming LIU Yong-shengkey laboratory for Bio-Resource and Eco-Environment Ministry of Education/{2. key laboratory of hydraulics and mountain river engineering College of Life Science sichuan university key laboratory for Bio-Resource and Eco-Environment Ministry of Education/State Key Laboratory of Hydraulics and Mountain River EngineeringCollege of Life ScienceSichuan University Institute of Biotechnology & Nuclear Techniques Sichuan Academy of Agricultural Sciences Crop Sciences Research Institute China Academy of Agricultural Sciences Biotechnology Research Institute China Academy of Agricultural Sciences Department of Plant Soil and Entomological SciencesUniversity of Idaho Moscow

Since maize is one of the most important cereal crops in the world,establishment of an efficient genetic transformation system is critical for its *** the current study,several elite corn lines were tested for suitability of Agrobacterium tumefaciens-mediated transformation by using immature embryos as *** ability and efficiency of transformation of *** *** EHA105 and LBA4404,different heat treatment times of immature embryos before infection,influence of L-cysteine addition in co-cultivation medium after transformation,and how different ways of selection and cultivation influence the efficiency of transformation were ***-resistant gene 2.G2.EPSPS was transformed into several typical maize genotypes including 78599,Zong 31 and BA,under the optimum *** showed that the hypervirulent Agrobacterium tumefaciens *** EHA105 was more infectious than *** of L-cysteine（100 mg L-1） in co-cultivation medium,and heating of the immature embryos for 3 min prior to infection led to a significant increase in the transformation *** in resting medium for 4-10 d and delaying selection was beneficial to the survival of resistant *** induction of germination,adding a high concentration of 6-BA（5 mg L-1） and a low concentration of 2.4-D（0.2.mg L-1） to regeneration medium significantly enhanced germination *** the optimized transformation procedure,more than 800 transgenic plants were obtained from 78599,Zong 31 and *** spraying herbicide glyphosate on leaves of transgenic lines,we identified 66 primary glyphosate-resistant *** transformation efficiency was 8.2..PCR and Southern-blot analyses confirmed the integration of the transgenes in the maize genome.

关键词： maize immature embryo Agrobacterium tumefaciens-mediated transformation transgenic approach glyphosate resistance

THREE-DIMENSIONAL TURBULENCE NUMERICAL SIMULATION OF A STEPPED SPILLWAY OVERFLOW

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Journal of Hydrodynamics 2002年第3期14卷 70-75页

作者： Chen Qun College of Hydraulic and Hydroelectric, sichuan university, chengdu 610065,{2.Dai Guang qing state key hydraulics laboratory of High Speed Flows, sichuan university, chengdu 610065,{2.Zhu Fen qing Geotechnic engineering Co., Second College of Hydraulic and Hydroelectric Sichuan University Chengdu 610065 China state key {2. laboratory of High Speed Flows Sichuan University Chengdu 610065 China Geotechnic engineering Co. Second Survey and Design Institute of Railway Chengdu 610031 China

In this paper, the k ε turbulence model is used to simulate the three dimensional turbulence flow over the stepped spillway at the Yubeishan reservoir. In order to solve the curved free water surface and to handle the complex boundary conditions, the fractional Volume Of Fluid (VOF) model that is applicable to the solution of the stratified two phase flow is introduced along with k ε turbulence model and the unstructured grid is used for the discretization of the irregular simulation domain. By these methods, the turbulence flow field of the stepped spillway is simulated successfully. The location of the free surface along the spillway, the magnitude and distribution of the velocity, the pressure on the step surface, the turbulence kinetic energy and turbulence dissipation rate are obtained by simulation. The changes and distributions of these characteristics along the width of the spillway are also obtained. The energy dissipation ratio of the stepped spillway is calculated according to the upstream and downstream water depth and velocities

关键词： stepped spillway turbulence numerical simulation turbulence model VOF model

THEORETICAL AND EXPERIMENTAL STUDIES OF HYDRAULIC CHARACTERISTICS OF DISCHARGE TUNNEL WITH VORTEX DROP

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Journal of Hydrodynamics 2010年第4期22卷 582-589页

作者： CHEN Hua-yong XU Wei-lin DENG Jun NIU Zhi-pan LIU Shan-jun WANG Wei state key {2. of hydraulics and mountain river engineering Sichuan University Chengdu 610065 China

The velocities at given points in the volute chamber,the contracted section and the vertical dropshaft of a discharge tunnel with vortex drop were measured by a small specially designed L-shaped tube,as Laser Doppler Velocimetry（LDV） or Particle Image Velocimetry（PIV） would not work there due to the special structure of the discharge tunnel with vortex *** empirical formulas were proposed to predict the velocities and the angles of the velocities made with the vertical direction θ.The theoretical analysis results were in good agreement with experimental ***,the method proposed in this paper can be used to analyze related characteristics of discharge tunnels with vortex ***,different model scales were considered to predict the cavitation characteristics on the wall of a dropshaft in practical engineering.

关键词： discharge tunnel with vortex drop dropshaft velocity wall pressure cavitation

Prediction Research of Deformation Modulus of Weak Rock Zone under In-situ Conditions

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Journal of mountain Science 2011年第2期8卷 345-353页

作者： ZHANG Yong HE JiangDa WEI Yufeng NIE Dexin School of Hydraulic and Hydroelectric engineering Sichuan University Chengdu 610065China state key {2. of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610059China

Weak rock zone (soft interlayer, fault zone and soft rock) is the highlight of large-scale geological engineering research. It is an important boundary for analysis of rock mass stability. Weak rock zone has been formed in a long geological period, and in this period, various rocks have undergone long-term consolidation of geostatic stress and tectonic stress; therefore, under in-situ conditions, their density and modulus of deformation are relatively high. Due to its fragmentary nature, once being exposed to the earth's surface, the structure of weak rock zone will soon be loosened, its density will be reduced, and its modulus of deformation will also be reduced significantly. Generally, weak rock zone can be found in large construction projects, especially in the dam foundation rocks of hydropower stations. These rocks cannot be eliminated completely by excavation. Furthermore, all tests nowadays are carried out after the exposure of weak rock zone, modulus of deformation under in-situ conditions cannot be revealed. In this paper, a test method explored by the authors has been introduced. This method is a whole multilayered medium deformation method. It is unnecessary to eliminate the relatively complete rocks covering on weak rock zone. A theoretical formula to obtain the modulus of deformation in various mediums has also been introduced. On-site comparative trials and indoor deformation modulus tests under equivalent density conditions have been carried out. We adopted several methods for the prediction researches of the deformation modulus of weak rock zone under in-situ conditions, and revealed a fact that under in-situ conditions, the deformation modulus of weak rock zone are several times higher than the test results obtained after the exposure. In a perspective of geological engineering, the research findings have fundamentally changed peoples' concepts on the deformation modulus of weak rock zone, provided important theories and methods for precise definit

关键词： Weak rock zone In-situ conditions: Stress Confining pressure Deformation modulus Multilayered

EXPERIMENTAL STUDY OF DAM-BREAK FLOW IN CASCADE RESERVOIRS WITH STEEP BOTTOM SLOPE

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Journal of Hydrodynamics 2011年第4期23卷 491-497页

作者： XUE Yang XU Wei-lin LUO Shu-jing CHEN Hua-yong LI Nai-wen XU Ling-jun state key {2. of hydraulics and mountain river engineering Sichuan University Chengdu 610065 China College of Water Conservancy and Hydropower engineering Xi＇an University of Technology Xi＇an 710048China

Dam break can cause a significant disaster in the downstream, especially, in a valley with cascade reservoirs, which would aggravate the disaster extent. The experimental studies of the dam-break flow of cascade reservoirs are few and far between at the present, Most of related studies concern the failure of a single dam.. This article presents an experimental study of the characteristics of an instantly filled dam-break flow of cascade reservoirs in a rectangular glass flume with a steep bottom slope. A new method was used to simulate the sudden collapse of the dam. A series of sensors for automatic water-levels were deployed to record the rapid water depth fluctuation. The experimental results show that, the ratio of the initial water depth of the downstream reservoir to that of the upstream reservoir would greatly affect the flood peak water depth in the downstream reservoir area and in the stream channel behind the downstream dam, while the influence of the dam spacing is insignificant. In addition, the comparison between the single reservoir and the cascade reservoirs shows some difference in the dam-break flow pattern and the stage hydrograph at the corresponding gauging points.

关键词： dam-break flow cascade reservoirs instantly full dam break steep bottom slope

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桩群数值模拟中的概化方法研究

水动力学研究与进展（A辑） 2008年第4期23卷 464-471页

作者：解鸣晓张玮谢慧姣河海大学海洋学院南京210098

建立数值水槽,将小尺度桩墩作为陆域边界直接模拟,利用有限单元法和三角形加密网格计算桩群影响下的二维流场。提出利用等效阻力法对桩群进行概化的研究思路,即将较为密集的原桩群概化为形式更加简单的其它形式桩群,并保证概化前后的桩... 详细信息

建立数值水槽,将小尺度桩墩作为陆域边界直接模拟,利用有限单元法和三角形加密网格计算桩群影响下的二维流场。提出利用等效阻力法对桩群进行概化的研究思路,即将较为密集的原桩群概化为形式更加简单的其它形式桩群,并保证概化前后的桩群绕流阻力相等。计算结果表明这种概化方式可以有效逼近原桩群引起的水位、流速变化,且对上下游大范围流场的影响与原桩群比较处在可以接受的误差范围内。此外文中也对等效阻力法和等阻水面积法概化的效果进行比较,结果显示等效阻力法较等阻水面积法更优,具有工程应用前景。

关键词：桩群直接模拟概化等效阻力法流场变化

Risk Analysis on Groundwater Resources Carrying Capacity Based on Blind Number Theory

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Wuhan university Journal of Natural Sciences 2007年第4期12卷 669-676页

作者： ZHANG Ji1,2.YU Sujun31. key laboratory of {2. Hazards and Surface Process,Chinese Academy of Sciences/Institute of {2. Hazards and Environment,Chinese Academy of Sciences,chengdu 610041,sichuan,china 2. Graduate university of the Chinese Academy of Sciences,Beijing 100049,china 3. School of Environmental Science and engineering,Southwest Jiaotong university,chengdu 610041,sichuan,china key laboratory of {2. Hazards and Surface Process Chinese Academy ofSciences/Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041Sichuan China

Blind numbers of evaluation indices about groundwater resources carrying capacity are defined from the concomitancy of randomness, fuzziness, grey property and unascertainment of groundwater system. Based on fuzzy theory, a comprehensive evaluation model on groundwater resources carrying capacity is constructed with blind information. Then a risk assessment model of surcharge about groundwater resources carrying capacity is established on blind reliability theory. The probable value ＂＊＂ matrix of fuzzy membership degree about carrying capacity corresponding to each judgment level can be obtained with the aid of blind algorithm as well as the subjective reliability ＂×＂ matrix. And then a graph of ＂groundwater carrying capacity v.s. accumulative reliability＂ can be gained Based on the graph, fuzzy membership degree of groundwater resources carrying capacity to each judgment level under different risk probability can be got. Thus, a comparatively reasonable judgment to groundwater resources carrying capacity might be obtained, with comprehensive analysis to the state of society, economy technology and ecology.

关键词： blind number theory groundwater resources carrying capacity evaluation risk analysis