膜孔灌溉田面综合糙率系数的确定     

吴军虎  费良军  王文焰 《灌溉排水学报》2001,20(1):32-34,54

根据膜孔灌溉田面水流运动特性 ,建立了膜孔灌溉田面水流运动零惯性量数学模型 ,并将其与优化理论相结合 ,提出了确定膜孔灌溉田面综合糙率系数的优化模型。实例计算与方法验证表明 ,该方法能够简单而有效地确定膜孔灌溉田面综合糙率系数。该研究成果为膜孔灌溉理论与技术的进一步研究奠定了基础  相似文献   

Hydrolysis and Condensation of Silane Agent for Metallic Surface Treatment   总被引：1，自引：0，他引：1  

XU Yi  TANG Shou yuan  TENG Yi  ZHANG Xiao feng 《保鲜与加工》2002,(10):72-74

Novel surface treatment technique by silane film is developing for metallic anti corrosion and coat improvement. The key points, hydrolysis and condensation, for the stability of the Silane agent(SA) solution is investigated, and the effective factors of stability for silane agent solution and the relative rule are discussed. It is found that stability of SA solution is related to the temperature, pH, solvents, SA concentration and additive by studying the state of the solution and the conductivity-time curve of SA solution. Meanwhile, controlling factors and improving methods for SA stability are proposed to guide the practical application of metallic surface anti-corrosion treatment by SA.  相似文献   

Strength and Microstructure of Sulphoaluminate Cement Containing Ultra- Fine CaCO3     

ZHOU Shi - hu  HUANG Jia - mu 《保鲜与加工》2006,(4):121-124

The existence of ettringite in sulphoaluminate cement hardened paste is mainly in the form of pole-like crystal,which causes unfavorable effect on the cement.In this paper the strength and microstructure of the sulphoaluminate cement containing ultra-fine CaCO_3 weze discussed.Experimet results show that the strength of sulphoaluminate cement was obviously improved by adding 3% of ultra-fine CaCO_3.After curing for 28d,the compressive strength of cement paste and mortar is 100.6MPa and 94.1MPa respectively,and the bending strength of the mortar reached 12.5MPa.SEM study on hardened paste of sulphoaluminate cement containing ultra-fine CaCO_3 showed that its structure was dense and homogeneous,there was hardly any massive crystall detected.  相似文献   

Calculating the Hollowing-center Grounding Device Resistance Based on the Surface Charge Simulation Method     

CHEN Xian-lu  YU Yu-ming  LIU Yu-gen 《保鲜与加工》2006,(4):21-24

An equivalent model for hollowing-center grounding device is proposed, the hollowing-center grounding device resistance is calculated with the surface charge simulation method and the computer programme is programmed based on this model. The accuracy of the model and method is validated by experimentation.  相似文献   

Dropwise Condensation Heat Transfer Coefficient on the Horizontal Circular Surface with Radial Gradient Surface Energy     

GU Yang-biao  LIAO Qiang  ZHU Xun  WANG Hong 《保鲜与加工》2006,(5):48-51

A theoretical model is developed for the dropwise condensation heat transfer on the horizontal circular surface with radial gradient surface energy based on the heat transfer model of individual condensate drop and the size distribution model of condensate drop on homogeneous condensation surface.The effect of variation of contact angle on the gradient surface on condensation heat transfer and condensate drop size distribution is taken account of in this model.The theoretical calculation method was obtained to predict the dropwise condensation heat transfer coefficient on the horizontal circular surface with radial gradient surface energy under various wall subcooled temperature,contact angle profile on wall surface,and working fluid.The effects of surface energy gradient,wall subcooled temperature,and thermophysical properties of condensate on the condensation heat transfer are discussed respectively.The calculation results show that the condensation heat transfer coefficient increases slightly with the increase of wall subcooled temperature.As latent heat and surface tension increasing,the condensation heat transfer coefficient increases.A larger surface energy gradient induces a larger condensation heat transfer coefficient.  相似文献   

Solution the Polarization Field Strength inside Ellipsoid in a Homogeneous Dielectric     

HU Wen-jiang  HU Xian-quan 《保鲜与加工》2001,(1):84-88

The solution of polarization field strength in ellipsoid and a homogeneous dielectric in condition of a constant external field is obtained with strict derivation and ellipsoidal coordinate. The conclusion that some textbooks given: the direction of polarization field strength with the direction of external field holds strict anti-parallel must be supplemented with additive certain conditions, otherwise it will not be correct. By means of the latticework and the step change calculation, the angle value of polarization vector with the external field is calculated and the changing situation about the angle value with the change of three half axes of ellipsoid is analysied.  相似文献   

Penetration behavior of bath induced by top-blown gas jets for steelmaking converter     

LI Mingming  LI Qiang  ZHANG Wei  ZOU Zongshu 《保鲜与加工》2015,(2):58-63

The cavity induced by top-blow gas jets impinging on the bath surface is one of most important parameters, which has overwhelming influence on the rate of slag formation and metallurgical performance. Water model experiments are conducted through a 1/10 scaled-down top-blown convertor. Effects of lance height and gas flow rate on penetration behavior are studied, and also the influence mechanism of liquid surface tension on penetration depth is addressed based on the experiments and theory analysis. An energy utilization index (EUI) is defined to reflect how much the impinging kinetic energy of gas jets are transferred into bath for formation of cavity, and an improved model is proposed to predict penetration depth of jets. The results show that penetration depth increases with lowering lance height and increasing gas flow rate, and impact diameter increases with increasing lance height, but is little affected by gas flow rate. Influence of liquid surface tension on penetration depth is enhanced with increasing surface tension and penetration depth. The EUI increases with increasing lance height, and a function relationship of it with lance height is obtained based on the experiments.  相似文献   

An Experimental Study on the Mechanical Property of the Gas-filled Coal   总被引：7，自引：0，他引：7  

Xu Jiang Xian Xuefu Du Yungui Zhang Guangyang 《保鲜与加工》1993,(5):42-47

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Predictions for the Strengths of Symmetry Composite Laminates Under Matrix Cracking     

WANG Fang  ZHANG Jun-qian  DING Jun 《保鲜与加工》2005,(2):93-96

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Experimental Research on High-strength Inorganic Anchoring Material     

PENG Xiao-qin  LIU Yan-meng  ZHONG An-xin  YANG Qiao 《保鲜与加工》2007,(2):113-115

A new type of inorganic anchoring material is developed as a substitution for anchoring adhesive to overcome some imperfections in the process of planting reinforcing steel bar.The mix proportion of the anchoring material is determined by experiments.The compressive strength,adhesive force to concrete,volume stability and anchoring force with steel bar are studied.The early strength of the anchoring inorganic material is quite high: for 1d up to 38.5MPa and 3d up to 60MPa.It is a good adhesive to concrete and the adhesive strength of 28d is about 2MPa.The anchoring material will have tiny volume expansion with the age,which is beneficial to enhancing the anchoring force.The essential component of the inorganic anchoring material is cement-based material,so some defects of the organic macromolecular material can be avoided,such as poor stability and requirement for vigorous construction conditions.Its characteristics in early strength,adhesive force to concrete and volume expansion can satisfy the requirement of the construction to the planting reinforcing steel bar and the loading force,thus it can be used as a substituting material for anchoring adhesive.  相似文献