Flow-Boundary Effects on Critical Submergence of Intake Pipe

In this study, the effects of intake-pipe blockage and location of impervious boundaries on critical submergence of an intake pipe are presented. Experiments were conducted on a horizontal intake pipe sited in a dead-end canal flow. Theoretical results and available experimental data are compared. It is shown that, as the distance between the intake-pipe entrance and the dead end gets smaller than the critical submergence depth, the deviation between theoretical and experimental results increases. A potential flow solution still gives acceptable results when this distance is smaller than the critical submergence, but it overpredicts by about 80% when the distance between the intake-pipe entrance becomes much smaller than the critical submergence depth.     

A closed-loop coherent acquisition scheme for PN sequences using anauxiliary sequence

We propose a closed-loop system for the acquisition of the pseudo-noise (PN) signal in direct-sequence spread-spectrum (DS/SS) systems. We introduce a novel idea of using an auxiliary signal, as opposed to the PN signal itself, for correlation with the incoming signal. The cross-correlation function of the auxiliary signal and the PN signal has a triangle shape that covers essentially the entire period of the PN signal. Consequently, their correlation provides the direction for the phase update of the local signal generator in the acquisition scheme. With coherent demodulation, the mean and variance of the acquisition time are derived under additive white Gaussian noise (AWGN). They are compared to those of the conventional serial-search acquisition system. Results suggest that the proposed system acquires the PN phase at least twice faster, with significantly smaller acquisition time variance, than the conventional system     

Ovariectomy-induced bone loss and the hematopoietic system

To investigate the relationship of the hematopoietic system to the loss of bone due to ovarian hormone deficiency, we examined the effects of ovariectomy and estrogen administration on the thymus, spleen and the bone marrow, and on the proliferation of marrow progenitors of osteoclasts. We also assessed the effects of daily administration of interleukin-1 receptor antagonist (IL-1ra) on bone loss due to ovarian hormone deficiency. Ovariectomy resulted in decreased cancellous bone volume, increased trabecular osteoblast and osteoclast numbers, and increased serum alkaline phosphatase levels that were prevented by 17 beta-estradiol treatment. Thymus weight, spleen weight, thymus and spleen lymphocytes, and bone marrow monocytes and lymphocytes also increased significantly following ovariectomy, and the increases were suppressed by 17 beta-estradiol. Ovariectomy, in addition, caused a 4-fold increase in the number of tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells formed in cultures of marrow cells and the increase was partially inhibited by 17 beta-estradiol. IL-1ra administration did not prevent the bone loss due to ovariectomy. Our findings indicate that ovariectomy-induced bone loss in the rat is accompanied by marked changes in the hematopoietic system, and that these changes are modulated by estrogen administration. In spite of the negative finding with IL-1ra, the nature of the involvement of the hematopoietic system in the pathogenesis of bone loss due to ovarian hormone deficiency merits continued exploration.     

Nutritional quality of uncultivated cereal grains utilised as famine foods in western sudan as measured by chemical analysis

The chemical composition of the grain of a number of wild grasses used as food in times of famine in western Sudan are reported and compared with those of the local staple cereals. Species investigated were Cenchrus hiflorus (haskaneet). Dactyloctenium aegyptium (korecb). Echinochloa colona (difra) and Oryza punctata (ruz el wadi). The grain of all species except C biflorus had protein contents in the range 110-140 g kg^?1, broadly similar to those of the local staple cereals. The grain of C biflours possessed a particularly high protein content of 210 g kg^?1. The nutritional quality of the proteins as measured by their chemical scores ranged from 20 for C biflorus to 65 for O punctata compared with scores of 36 and 58 for the local sorghum var Kurgi and millet respectively. Lysine was the limiting amino acid in all cases. Whilst the composition of the protein of sorghum var Kurgi was typical of sorghum generally, that of var Karamaka was unusual in possessing lysine levels of 3.4 g (16 g N)¹, double that normally present in sorghum and raising the chemical score of the protein to 62. The ash content of the famine food cereals was high, attaining 113 g kg¹ in C biflorus. All grains were good sources of zinc and D aegyptium. O punctata and E colonum additionally contained comparatively high levels of iron. Remarkably for a cereal D aegyptium was also very rich in calcium, containing over 10 g kg¹, and possessed high concentrations of manganese. Carbohydrate content of the famine food grains varied from 617 g kg¹ for C biflorus to 748 g kg¹ for O punctata, values comparable to the local staple cereals. The proportion of starch in this fraction ranged from 650 g kg¹ in D aegyptium to 940 g kg¹ in O punctata. Seed oils of all species were predominantly unsaturated containing mainly oleic and linoleic acids.     

不锈钢螺栓连接节点的破坏研究

尽管不锈钢与碳素钢的机械性能有显著的不同,但是现有规范关于不锈钢连接节点的设计规定都基于碳素钢的设计准则。对于不锈钢螺栓连接节点的设计抗力,EN1993-1-4和SCI/EuroInox(美国《科学引文索引》/欧洲不锈钢协会)的不锈钢设计手册基于EN1993-1-8和EN1993-1-3作了一些小修改。研究了厚板和薄板的不锈钢螺栓连接节点的承载性能。提出了一个奥氏体不锈钢和铁素体不锈钢试件的数值分析模型,并证明其正确性。将该模型用于螺栓节点承载力的参数分析,可研究主要变量对其影响。这些参数包括螺栓边距e2,端距e1和板厚t。结果表明,不锈钢螺栓节点的变形性能与碳钢节点存在某种程度的不同。数值模型中最初出现裂纹的部位与试验中观察到的不锈钢节点和碳素钢节点相符,这种相符性被作为定义一种强度失效准则的基础。以参数分析结果为基础的不锈钢螺栓连接节点承载能力极限状态和正常使用极限状态设计法则比现行的EC3法则更加经济和简捷。