ANALYTIC SOLUTION OF CYLINDRICAL SHELL ROOF UNDER GENERAL TRANSVERSE LOCAL LOADINGS

This paper uses the method of mixed-type series to derive the analyticsolution of cylindrical shell roof,being simply supported transversely,arbitra-rily restrained longitudinally and subjected to gereral transverse local loads.This paper also presents the analytic expressions of the solutions for somekinds of local load.Some examples of this kind of shell roof subjected to ainlined single force near the middle of it with free lorgitudinal edges aregiven.The computation shows that the convergence of the solution is woll     

卷盘式喷灌机卷盘驱动负载计算与分析

为优化卷盘式喷灌机驱动结构,研制高效卷盘喷灌机驱动器,需要对卷盘式喷灌机的卷盘负载情况进行计算和分析。为此,以软管牵引式卷盘喷灌机为对象,建立了卷盘负载转矩计算的物理模型,理论推导了在运行时的卷盘负载转矩数学计算模型。以JP50和JP75型卷盘式喷灌机为例,按推导所得数学模型进行计算,得到了运行时卷盘负载转矩随已回卷PE管长度的变化规律和估计值。计算结果表明:JP50型卷盘式喷灌机运行时最大负载转矩约为960N·m,JP75型为6 001N·m;卷盘负载转矩随已回卷长度的增加而减小,且当卷盘回卷半径变化时,负载转矩将突然变大;负载转矩的大小和变化规律只与喷灌机的参数和运行条件有关,与运行时的速度无关。     

Developmental abnormalities in the ovule and embryo sac of ulluco (Ullucus tuberosus) and their effect on seed set

Summary Ulluco (Ullucus tuberosus) is a vegetatively propagated crop plant that flowers abundantly but sets only few seeds. We examined if the low seed/ovule ratio can be explained by morphological abnormalities in ovules, embryo sacs or embryos. In 35 clones growing in the actual area of cultivation in Ecuador and in 5 clones grown in Finland flowers were analysed by clearing technique. About half of all analysed clones contained ovules and embryo sacs whose development was arrested, in two clones there were embryo sacs whose cell patterns were abnormal and in four clones there were double embryo sacs. There were both normal and abnormal ovules and embryo sacs in the same plant. Genetic load is suggested to be one of the causes for the low sexual fertility found in ulluco. It may be incapable of maintaining homeostasis of development of the ovule and embryo sac in a varying environment. The occurrence of developmental abnormalities should be studied in each clone intended for inclusion in traditional breeding programmes.     

STATIC ANALYSIS OF THE BODY OF MAN''S DRY GAS HOLDER WITH A VOLUME OF 120000m~3

This paper presents finite element calculations of the body of MAN'S dry gas holders with a volume of 120000m~3 under internal pressure and wind load. The analyses of displacements and internal forces of the body are presented. The control points of strength and rigidity check are determined. The work in this paper is very valuable to body's design.     

Determination of Load Share between Gear Teeth with Contact Finite Element Method

The determination of load share between teeth is a complex problem in gear strength calculation. On the basis of contact finite element method this paper considers the production-assembly error as initial gap to get the finite element model which meets load share between teeth in gear meshing. Through calculating and comparing the result with that from ISO formula to get the load share between teeth which meets the requirements in actual usage.     

多源沉积物对地表水中磷铜锌浓度的影响

受多来源沉积物污染影响的水体中可溶性P,Cu,Zn实际浓度常明显低于按各自沉积物的比例与释放量计算的理论值。沉积物之间的性质差异越大,实际测定值与计算值之间的差异也越大。多来源沉积物水体中可溶性P,Cu,Zn的浓度主要受P,Cu,Zn释放能力最强或对P,Cu,Zn吸持能力最强的沉积物比例控制。