THE STUDY OF STRAIN FATIGUE CRACK PROPAGATION BEHAVOURS OF VANADIUM BEARING HSLA STEEL

In this paper, the strain fatigue: crack propagation rates of vanadium bearing HSLA steel with different micro-structures are measured under constant load conditions, and the relationship between the crack propagation rate and the microstructures of steel is also studied.     

THE DETERMINATION OF A CRACK IN STEEL FIBRE REINFORCED LIME-SAND CONCRETE

This paper studies the determination of a crack in steel fibre reinforced lime-sand concrete and its precision by acoustic emission(AE).The main AE paramters which influencethe precision of the determination of a crack are introduced,The properties of the lime-sand concretecan be increasted greatly with the steel fibre,The result in this paper can be used in the study of fi-bre re inforced cement concrete.     

间断热辐射对钢板仓中稻谷温度和水分影响的模拟研究

运用远红外电热幕对装有0.8m3稻谷的钢板仓进行热辐射,研究太阳辐射对钢板仓中粮温传递的影响。稻谷初始湿基水分含量为14.75%±0.35%,辐射时控制模拟仓辐射面温度分别为30℃、45℃和60℃,每个条件试验周期为6d,辐射时间为8:00到20:00。结果表明,距辐射面相同粮层温度上升速率随辐射温度上升而增大;相同辐射条件下升温速率随粮层厚度增大而下降。距辐射面5cm和15cm粮层受环境温度影响,粮温白天上升夜间下降;25cm、35cm和55cm粮层在整个试验过程中粮温持续缓慢上升;75cm粮层从第36h开始温度缓慢上升,相同辐射条件下不同粮层升温速率差异性显著(p0.05)。拟合得到时间(T)和粮层厚度(S)的二元二次粮温上升速率方程:V=a-bT-cS+dT2+f(T-72)(S-0.35)-g(S-0.35)(T2-6336),a、b、c、d、f、g为常数,R2≥0.832,该方程可预测不同时间、不同粮层厚度的升温速率。     

高湿条件下温度对储藏稻谷水分和脂肪酸值的影响研究

通过模拟储藏,研究了高湿(85%)条件下温度对储藏稻谷水分和脂肪酸值的影响。结果表明储藏环境的温度和时间对稻谷的水分、脂肪酸值有显著影响,随着储藏温度的升高和时间的延长,水分呈上升、平稳、下降的趋势,而脂肪酸值呈增加的趋势。稻谷水分(W)和脂肪酸值(F)、储藏温度(T)、时间(D)的二元线性回归方程分别为W=-0.04411T-0.02783D+17.4809(R2=0.457271,P<0.01),F=0.432343T+0.549133D-2.99971(R2=0.91418,P<0.01)。进一步的研究表明稻谷霉菌量和脂肪酸值相关系数高达0.798521,稻谷脂肪酸值的变化主要是由霉菌引起。     

THE EFFECT OF THE CONVECT1VE HEAT TRANSFER IN THE ENTRANCE REGION OF THE TUBE ON THE HEAT TRANSFER IN THE TRBE -MOUTH REGION OF THE HIGH TEMPERATURE HEAT EXCHANGE EQUIPMENT

The effect of the convective heat transfer in the entrance region of the tube on the temperature field and the maximum temperature of the tube material in the tube -mouth region of the high temperature heat exchange equipment is examined by numerical analysis. The computations on the basis of four different formulas for convection heat transfer coefficient are performed. The computed results indicate that the efect can not be ignored as for heat protection of the tube -mouth region and it is resapnable and secure that the mean convective heat transfer coefficient with taking account of the effect of the entrance region is used in the thermal design of the tube -mouth region.     

川渝地区偏高水分稻谷和小麦实仓安全储藏预警技术研究

研究了川渝主要储粮区(中温高湿区)偏高水分稻谷和小麦的实仓安全储藏预警技术。实仓试验结果表明,在常规储粮条件下,稻谷和小麦中早期储藏危害真菌的生长均明显受到水分、初始带菌量和温度等因素的影响,小麦的耐藏性和储藏安全性明显优于稻谷。早期储藏危害真菌的数量变化可以作为监控即时粮情的重要参考指标,其良好的预警作用(高灵敏性和及时性)对粮食安全储藏具有十分重要的意义。