新型矩形钢管混凝土柱节点轴压传力机制研究

针对在矩形钢管混凝土柱楼层节点区钢管内设置分配梁和内环肋这种节点新形式,研究分析该设置传力构件的矩形钢管混凝土柱轴压荷载作用下的受力机理,揭示其能有效协调钢管壁与内部混凝土的变形与受力,迫使钢管壁与内部混凝土共同承受外荷载的功效.试验验证表明,节点设置传力构件改善了矩形钢管混凝土柱的受力性能,在此基础上提出了传力构件分配梁的设计方法.     

三角形钢屋架力学计算模型的研究

对三角形钢屋架的杆件类型及立柱抗侧刚度因素对屋架的内力影响进行了研究．由于三角形屋架的弦杆制作通常采用整根杆件制作,与腹杆用节点板连接,并支撑于钢立柱上,因此弦杆杆件类型及立柱侧移刚度对屋架内力有一定影响．本文利用MIDAS对某仓库工程三角形屋架进行了4种力学模拟计算,通过对比：设计时,三角形钢屋架的弦杆按梁单元是必要的,同时不考虑立柱抗侧刚度对屋架内力影响．对此类屋架设计本文提出了明确的计算方法,具有较高的实用价值．     

Implicit Epistemic Aspects of Constructive Logic

In the present paper I wish to regard constructivelogic as a self-contained system for the treatment ofepistemological issues; the explanations of theconstructivist logical notions are cast in anepistemological mold already from the outset. Thediscussion offered here intends to make explicit thisimplicit epistemic character of constructivism.Particular attention will be given to the intendedinterpretation laid down by Heyting. This interpretation, especially as refined in the type-theoretical work of Per Martin-Löf, puts thesystem on par with the early efforts of Frege andWhitehead-Russell. This quite recent work, however,has proved valuable not only in the philosophy andfoundations of mathematics, but has also foundpractical application in computer science, where thelanguage of constructivism serves as an implementableprogramming language, and within the philosophy oflanguage.\footnote{Nordstr\"{o}m et al. (1990) give an overview of the work in computerscience, whereas Ranta (1995) provides an impressiveconstructivist alternative to Montague Grammar usingthe richer type structure of Martin-L\"{o}f in placeof the simple classical type theory of Church.} Mypresentation will be carried out through a contrastwith standard metamathematical work.\footnote{Troelstra and van Dalen (1988) give an encyclopedictreatment of the metamathematics of constructivism.}In the course of the development I have occasion tooffer some novel considerations (in Sections~6 and 8) on thenature of proof and inference(-acts).     

群盲签名的通用可组合性研究

协议的UC安全性可以确保它在并发环境下运行的安全性。本文在UC框架下提出了一个群盲签名的理想函数,并在离散对数假设下构造了一个具有UC安全的群盲签名协议。然后,分析了此协议的安全性并详细地证明了群盲签名可以安全实现理想函数。     

Influences of elastic foundations and shear deformations on the buckling behavior of functionally graded material truncated conical shells under axial compression

This article presents an investigation on the buckling of functionally graded (FG) truncated conical shells under an axial load resting on elastic foundations within the shear deformation theory (SDT). The governing equations are solved using the Galerkin method, and the closed-form solution of the axial buckling load for FG conical shells on elastic foundations within the SDT is obtained. Various numerical examples are presented and discussed to verify the accuracy of the closed-form solution in predicting dimensionless buckling loads for FG conical shells on the Winkler–Pasternak elastic foundations within the SDT.     

再生砖骨料多孔混凝土微观结构及结构模型

为了深入研究再生砖骨料多孔混凝土的微观结构,从本质上认识其性状及规律,引入扫描电镜研究再生砖骨料多孔混凝土界面过渡区微观形貌;根据混凝土中心质假说分析概括再生砖骨料多孔混凝土结构模型,定性研究微观结构与宏观性能的关系,探索界面过渡区形貌和骨料大中心质效应对再生砖骨料多孔混凝土宏观性能的影响。结果发现再生砖骨料多孔混凝土具有较好的界面过渡区结构,结构密实,水化产物丰富,水灰比、目标孔隙率、养护龄期,矿物掺料对结构的密实程度和水化产物的类型、数量有一定影响,进而影响强度。多孔混凝土存在较多负中心质效应,大中心质只有再生砖骨料。今后应当把研究负中心质效应作为重点。     

CMQV+:An authenticated key exchange protocol from CMQV

Ustaoglu presents a secure and efficient key exchange protocol named CMQV,based on the design rationales of HMQV and NAXOS.Compared with the latter two protocols,on one hand,CMQV achieves high performance of HMQV,and on the other,it is proven secure in eCK model as NAXOS is.However,CMQV enjoys the security proof under gap Diffie-Hellman assumption as indicated by its creators.In this paper,we propose a variant of CMQV,called CMQV+,which is proven secure under a weaker assumption (i.e.computational Diffie-Hellman assumption) in eCK model with random oracles while maintaining the high-performance feature of CMQV as much as possible.     

Influence of firing temperature on the ceramic properties of clays from Campos dos Goytacazes, Brazil

The characteristics of two clays used for red ceramic production in Campos dos Goytacazes, southeast of Brazil, were investigated. Characterization was performed by X-ray diffraction, chemical analysis, as well as granulometric and plasticity measurements. Technological properties related to water absorption, linear shrinkage and flexural strength were obtained from specific tests. Samples were prepared by pressing clay bodies at 20 MPa, which were then fired at temperatures from 850 to 1200 °C. The results showed that both clays from three deposits are highly plastic due to the elevated percentage of kaolinitic clay minerals. The samples richer in clay minerals present higher linear shrinkage as well as a decrease in water absorption in comparison to the others. The effectiveness of these clays for red ceramic production has been discussed in terms of the Winkler diagram.     

边界元和分层总和法联合解弹性地基板

用无奇点边界元法和土力学中的分层总和法联合处理弹性地基上的薄板,求解板上选点的挠度,从而求得板的内力。利用了两种方法的优点,使求得的结果精度高且更符合实际。     

一种基于偏微分方程的文本图像版面分割方法

文章提出了一个基于属性签密方案,相比较单纯的基于属性加密和基于属性签名方案,该方案的计算量和通信成本远远低于传统的先签名后加密,且具有抗合谋攻击性。方案的安全性依赖于计算性Diffie-Hellman假设和判定性Bilinear Diffie-Hellman假设,并且在随机预言模型下证明了该签密方案在选择属性集和选择消息攻击下是安全的。