动态规划模型在生产存贮中的应用

利用动态规划模型研究了生产管理中生产存贮问题的数学模型，给出了动态规划的最优性原理和动态规划基本方程，并给出了该数学模型求解的一个实例。     

苏词中的婉约成分再解读

北宋文学家苏轼文学艺术成就斐然,是宋词的代表人物,其豪放词题材广泛,思想格调高远,表现形式新颖,风格多种多样,语言沉郁,雄健豪放。但是就现存的苏轼词三百四十余首来看,其豪放词占少数,绝大多数的还是婉约词。苏轼的婉约词其实也是婉约派的集大成者,他的婉约词清新委婉,一扫晚唐五代词的绮丽艳科的萎靡之风,开创了婉约词的新局面。     

Différentes déclinaisons de l'aléa liquéfaction: de la cartographie préventive au projet

As part of its Public Service, Applied Research, and Client Service activities, BRGM's Thematic Centre for Natural Geological Risks (NGR) has recently undertaken studies in order to characterize "liquefaction hazard". The paper considers definitions and presents several approaches to liquefaction hazard assessment, demonstrated by several examples. The first approach is a naturalistic one: Hazard assessment is considered in a structured manner by undertaking: – a regional inventory of historic events – mapping of formations susceptible to liquefaction in homogeneous risk areas subject to seimic activity – preventive mapping of the phenomena at local scale The second approach is a semi-deterministic one: It allows to produce a seismic microzonation, considering parametric calculations and charts (Seed's reverse method). This approach can be used also to recommend soil improvements when liquefaction hazard does exist. The third approach is a deterministic approach: It takes into account a 3D geotechnical model of the analysed area, as well as specific charts to produce a liquefaction hazard assessment of soils and an advanced seismic microzonation. This method was used in Guadeloupe and Martinique districts (French Lesser Antilles) ad for the design of a new TGV railway track in the south of France. The proposed methodology relies on the French Association for Earthquake Engineering recommendations and brings some innovative aspects: combined naturalistic and geotechnical analyses for liquefaction hazard assessment, combined chart use and 3D geotechnical modelling for liquefaction hazard microzonation. Apart from the complete analysis of the liquefaction hazard not always being useful, it also demands major resources, and is consequently sometimes broken down into several less-detailed stages. The various examples considered thus form a continuum and are simply variations of a same definition of the liquefaction hazard: where: X, Y and Z=coordinates t=time Δu=interstitial over-pressure σ'_vo=initial effective stress I_L=Iwasaki's liquefaction index     

不同气速下喷动床喷泉区颗粒特性的模拟分析

以欧拉多项流模型为基础,对底角锥度为60°、床直径为0.44 m的喷动床内气固两相流的动力学特性进行了模拟研究,并对不同气速下喷泉高度、颗粒体积分数、颗粒速率的变化进行分析,结果发现喷泉高度与进口气速在u/ums=1.2～1.8范围内具有良好的线性关系,拟合度可达到0.9997。固体颗粒体积分数在轴心区域较高,随着径向距离的增加逐渐下降,且随高度的增加呈现先减小后增大的趋势;颗粒体积分数受速率的影响较大,随着喷动速率的增大,颗粒体积分数趋于减小,但减小幅度不同。颗粒速度在喷泉核心区随床层高度增大而减小。同一床层高度上的颗粒速度随气速的增加而增大,但增大值不同。     

留法勤工俭学运动中蒙达尼派与勤工派的争论

192 1年初 ,留法勤工俭学生面对勤工俭学的艰难出路提出是先求学还是先找工作的问题 ,由此引发蒙达尼派与勤工派的激烈论争。论争焦点在于 :自工自读还是官费津贴 ;以勤工还是俭学为目的 ;社会革命问题。双方论争对于留法勤工俭学思想觉悟有一定推动作用。     

高体积分数SiCp/Al电子封装复合材料的钎焊综述

高体积分数SiC_p/Al复合材料作为电子封装材料使用日益流行,其钎焊具有重要的实际意义。近来,一些新钎料合金和工艺被开发用于高体积分数SiC_p/Al复合材料的钎焊。本文回顾了SiC_p/Al复合材料的物理力学性能和制备工艺,综述了应用于高体积分数SiC_p/Al复合材料的合金钎料、钎焊工艺及其接头微结构与性能,旨在进一步理解它们之间的关联性,以优化接头性能与可靠性。往Al?Si合金中添加Cu、Mg、Ni等合金元素有助于提高钎料合金和钎焊接头的使用性能,如可优化钎料合金的应用温度、接头界面结合和焊缝强度。而表面金属化和超声波振动两种钎焊辅助工艺可通过避免或去除复合材料表面的Al₂O₃和SiO₂氧化膜来改善合金钎料的钎焊性。最后,指出需要进一步加强对合金钎料的优化设计、表面金属化工艺以及焊料/涂层/基材体系之间的润湿性和界面行为的研究。     

Structured packing liquid holdup in cryogenic systems

Experimental results and a theoretical analysis are presented on structured packing liquid holdup under cryogenic conditions. The experimental tests were performed on a novel laboratory unit incorporating a gas lift pump to recirculate the cryogenic liquid in a flow visualization dewar. Holdup is measured by sensing the difference in level in the dewar when the liquid flow is shut off after a constant operation at a given liquid loading. A dimensional analysis is performed to identify the important system properties that affect the liquid holdup. The preliminary experimental data are compared against a correlation developed from the dimensional analysis.     

论京派诗话小说理想世界的三重境界

论述了京派诗话小说理想世界的三重境界,即重构人类童年乐土、抒写美好人性神话和追问生命本质意义,表达了京派诗话小说家对生命本质的认识。     

Sphingomyelin Deacylase,the Enzyme Involved in the Pathogenesis of Atopic Dermatitis,Is Identical to the β-Subunit of Acid Ceramidase

A ceramide deficiency in the stratum corneum (SC) is an essential etiologic factor for the dry and barrier-disrupted skin of patients with atopic dermatitis (AD). Previously, we reported that sphingomyelin (SM) deacylase, which hydrolyzes SM and glucosylceramide at the acyl site to yield their lysoforms sphingosylphosphorylcholine (SPC) and glucosylsphingosine, respectively, instead of ceramide and/or acylceramide, is over-expressed in AD skin and results in a ceramide deficiency. Although the enzymatic properties of SM deacylase have been clarified, the enzyme itself remains unidentified. In this study, we purified and characterized SM deacylase from rat skin. The activities of SM deacylase and acid ceramidase (aCDase) were measured using SM and ceramide as substrates by tandem mass spectrometry by monitoring the production of SPC and sphingosine, respectively. Levels of SM deacylase activity from various rat organs were higher in the order of skin > lung > heart. By successive chromatography using Phenyl-5PW, Rotofor, SP-Sepharose, Superdex 200 and Shodex RP18-415, SM deacylase was purified to homogeneity with a single band of an apparent molecular mass of 43 kDa with an enrichment of > 14,000-fold. Analysis by MALDI-TOF MS/MS using a protein spot with SM deacylase activity separated by 2D-SDS-PAGE allowed its amino acid sequence to be determined and identified as the β-subunit of aCDase, which consists of α- and β-subunits linked by amino bonds and a single S-S bond. Western blotting of samples treated with 2-mercaptoethanol revealed that, whereas recombinant human aCDase was recognized by antibodies to the α-subunit at ~56 kDa and ~13 kDa and the β-subunit at ~43 kDa, the purified SM deacylase was detectable only by the antibody to the β-subunit at ~43 kDa. Breaking the S-S bond of recombinant human aCDase with dithiothreitol elicited the activity of SM deacylase with ~40 kDa upon gel chromatography. These results provide new insights into the essential role of SM deacylase expressed as an aCDase-degrading β-subunit that evokes the ceramide deficiency in AD skin.