Analysis on Longitudinal Cracks and Deflection of the Pre-stressed V-shape Slab Roof Structure     

YANG Hong-yuan  FAN Ze-bao  CUI Jia 《保鲜与加工》2002,(3):112-116

In this paper, the finite element method is used to analyze the behavior of the prestressed V-shape Slab Roof structure, especially the effect of temperature change on the stress of slab. The calculated results indicate that when the temperature changes, the tensile stress at the lower extreme fibers of the flange plate near rib exceeds the tensile strength of concrete subjected to the combined action of triaxial stresses and results in the longitudinal cracks of the flange plate. The deflection analysis is based on the mechanical model of the prestressed V shape slab with the longitudinal cracks. The calculated results are in general agreement with the field observations.  相似文献   

Artificial Neural Networks Models for Flow Stress during High Temperature Plastic Deformation of Al-Li Alloy     

LIU Xue-feng  WANG Ling-yun 《保鲜与加工》2001,(2):68-71

Using gained experimental data to develop the models of stable flow stresses at high temperature plastic deformation by statistical methods for alloy materials, precision of the models is poor and at the same time the processes of modeling are complicated with great workload. On the basis of the data obtained on Gleeble-1500 Thermal Simulator,the predicting models for the relation between stable flow stress during high temperature plastic deformation and deformation strain, strain rate and temperature for 1420 Al-Li alloy have been developed with BP Artificial Neural Network method. The results show that the model on basis of BPNN is practical and it reflects the real feature of the deforming process. It states that the difference between the real value and the output of the model is in order of 5 percent.  相似文献   

Numerical Simulation of Flow field and Temperature field in Combustion Chamber Widened Suddenly     

Wu Chenbo Liang Xiaoping 《保鲜与加工》1997,(2):117-122

The flowfield and temperature field are numerically Simulated by the mathematical model of the fluid flow and heat transfer in circular combustion chamber widened suddenly. The distributions and influence factors of the flow field and temperature field are studied in it. The results have the guiding significance for the design of combustion chamber. The mathematical models can serve as the quantitative analysis methods for design.  相似文献   

Recommendations on Shrinkage and Temperature Reinforcements in Concrete Slabs     

LI Lei 《保鲜与加工》2004,(4):45-50

The mechanism of shrinkage cracking is discussed with a simple member, which is fully restrained and subjected only to an axial restraining force caused by shrinkage, while a simple procedure is presented for the determination of the number and spacing of the cracks and the average crack width. With the simple model, some examples are shown to compare the provisions for minimum shrinkage and temperature reinforcement in GB 50010-2002 Code, ACI 318-02 Code and AS 3600-1988 Code. The results show that the provisions in GB 50010-2002 Code are too weak in comparison with the others. Finally, some recommendations are proposed.  相似文献   

EFFECT OF MICRO-GALLIUM ON THE INTERGRANULAR SEGREGATINN OF PHOSPHORUS IN CARBON STEELS     

He Zefu Wu Yunjian 《保鲜与加工》1988,(4)

The effect of small amounts of gallium on the intergranular segregation of phosphorus in carbon steels is discussed, with the help of the impact test, fracture morphology and micro-structure analyses, combined with composition analysis on the fracture surfaces by Auger electronspectrometer. The results show that gallium in the steel with a content of gallium more than ten thou-sandth can suppress, to some extent, the intergranular segregation of phosphorus and retard the tempering process. As a result, the temper embrittlement of the steel disappears and the embrittlement transition temperature declines.  相似文献   

Research on Optimum System of Slag Making of ANYANG Iron & Steel CO.BF     

Wen Guangyuan Peng Henian 《保鲜与加工》1997,(6):30-35

  相似文献   

Converse Illation Method on Optimal Control of Reheating Furnace     

DUAN Ying  LIN Tao  DUAN Wen-ze 《保鲜与加工》2007,(8):21-25

  相似文献   

以粮温实测数据为例探讨低温储粮的可行性   总被引：1，自引：0，他引：1  

张前 《粮食储藏》2004,33(3):3-6

通过对高大平房仓粮温进行跟踪检测，分析比较了粮温变化情况，并探讨了低温储粮的可行性。  相似文献   

不同强度温度刺激对棉花黄萎病的影响   总被引：5，自引：0，他引：5  

简桂良  邹亚飞  王天存  马存 《棉花学报》2003,15(2):83-86

采用三个不同抗性的棉花品种、三个不同的黄萎病菌系和三个温度梯度,完全随机区组设计,在人工气候箱中研究刺激不同时间对棉花黄萎病发病的影响。结果表明,刺激温度的高低和品种的抗性对棉花黄萎病的发生与扩展有显著的影响,而菌系致病力以及刺激时间长短对棉花黄萎病的发生也存在显著差异,但影响较小;品种的抗病性对棉花黄萎病的发生起着至关重要的制约作用;温度对黄萎病的发生与扩展起着关键作用。初步明确了影响棉花黄萎病发生与扩展的几个因子间的互作效应及其影响程度。  相似文献   

热带区域冬玉米物候发育的模拟与模型检验   总被引：1，自引：0，他引：1  

李超  李文峰  钱晔 《中国农学通报》2015,31(24):53-58

为探索热区环境下冬播玉米物候发育的温度效应,建立具有较好解释性的冬玉米物候发育模拟模型。基于云南陇川、瑞丽、芒市三试点分品种和播期的3年试验资料,比较不同模拟方法对冬玉米物候期的预测效果。结果显示以0℃、6℃、8℃、10℃为下限温度的积温模型,预测精度均不高,根均方差(RMSE)为7~11天。因此本研究在WOFOST模型基础上,以日最高温、日最低温2个驱动变量取代日均温,为不同物候期分别设置基点温度,基于物候期分段函数、建立了新的冬玉米物候发育模拟模型。模型采用独立试验数据进行检验,对两供试品种物候期预测的RMSE分别为4.42天和4.19天。模型体现了日温变化对发育速率的影响,体现了不同物候期温度效应的差异,具有较好的机理性,模型预测精度较高。  相似文献