Dendritic growth of ice crystals during the freezing of beef

The morphology adopted by ice in frozen tissues is accepted as one of the factors responsible for freezing damage. For this reason ice nucleation and growing mechanisms have been extensively studied. However, under the conditions used in the industry, where important temperature gradients exist, the classical analysis of nucleation and growth, depending on the supercooling, is complicated by the dendritic growth of crystals as well as by the possibility of the location of the ice crystal inside or outside the cells. In the present paper experiments which verify the existence of dendritic ice growth during the freezing of beef are described. The dendritic growth rate of ice in beef is measured as a function of the supercooling and an analysis of the expected mechanism, according to freezing conditions, is also provided.     

Thinning algorithms for gray-scale pictures

Elongated black objects in black-and-white pictures can be ``thinned' to arcs and curves, without changing their connectedness, by (repeatedly) deleting black border points whose deletion does not locally disconnect the black points in their neighborhoods. This technique generalizes to gray-scale pictures if we use a weighted definition of connectedness: two points are ``connected' if there is a path joining them on which no point is lighter than either of them. We can then ``thin' dark objects by changing each point's gray level to the minimum of its neighbors' gray levels, provided this does not disconnect any pair of points in its neighborhood. Examples illustrating the performance of this technique are given.     

用5-苯基-环己烷-1,3-二酮-4-碳酰替苯胺作双基推进剂的安定剂

用5-苯基-环己烷-1,3-二酮-4-碳酰替苯胺作双基推进剂的安定剂,在安定性试验中得到了较好的结果。试样在100℃时贮存12天后,用不同的溶剂提取,以柱形色层分离法分离1,3-二酮安定剂的各种硝基衍生物。     

以褐煤腐植质为基础制取染料

证明了以褐煤腐植质为基础制取木材染料的可能性。完成了各种因素对提取染料过程影响的评价。制取了符合工业上需要的用于木材的腐植染料。     

The ergonomic evaluation of work stress in the furniture industry

In some furniture factories an ergonomic analysis of work stress was carried out at 10 workplaces typical for this industry. Physical and psychological stress, the influence of the work environment and some elements of the work-organization were measured. In order to compare the stress at the different workplaces, a point scale was applied. This investigation showed that the energy expenditure of the workers varied between 1026 and 1937 kcal during one shift. Psychological stress was not large. Environmental conditions were stressful. Noise levels at all locations exceeded 90 dB(A), and lighting was inadequate. The investigations also showed that the greatest stress appeared in the operation of the horizontal belt sanding machine and of the tilting arbor saw. The least stress was observed in the operation of the hydraulic hot-plate press and of the edge-glueing press-chain conveyor system.     

基于两相漂移流理论的蒸汽发生器计算程序(CCM)的应用

介绍了一个建立在两相漂移流和相边界可连续移动模型基础上的、可较为全面描述单相及两相流的传热和流动的程序CCM.该程序通过"修正的有限元方法"对控制体节点之间建立联系,保证模拟效果的同时,节省了计算时间.以CCM为基础的UTSG-3程序可较好地模拟U型管蒸汽发生器的稳态和瞬态过程,可得到更为广泛的应用.通过不同运行参数的扰动研究了大亚湾核电站蒸汽发生器动态响应过程,结果显示UTSG-3程序具有模拟U型管蒸汽发生器动态行为的能力.     

热轧过程中的微观组织预测

为了模拟轧制钢板产品的条件下微观组织的演变,建立一个三维的有限元模型并采用相应的计算方法. 为了研究轧制参数例如轧制速度、板子的压下量对变形行为以及微观组织演变的影响进行一系列的有限元仿真,对进行热轧参数的选择提供必要的依据,从而可以对设计好的微观组织的材料进行加工处理.