Surprising strength of silkworm silk

Commercial silkworm silk is presumed to be much weaker and less extensible than spider dragline silk, which has been hailed as a 'super-fibre'. But we show here that the mechanical properties of silkworm silks can approach those of spider dragline silk when reeled under controlled conditions. We suggest that silkworms might be able to produce threads that compare well with spider silk by changing their spinning habits, rather than by having their silk genes altered.     

新型国有企业三维监管体制及运行机理研究

伴随国企改制与政府职能转型的社会背景,新型国有企业(文章中简称为新国企)应运而生。相较于传统国有企业,新型国有企业具有全新的定义与内涵,因此需要面对全新的监管问题与监管需求,其对应的监管体制也亟需调整与转型升级。笔者通过对新型国有企业的深入解读与剖析,对新型国有企业需要的新型监管模式进行理论探讨。结合新型国有企业的3种监管目标政治目标、经济目标和社会目标,系统梳理了新型国有企业监管体制的监管主体和监管对象。在此基础上,提出并构建了基于主体-对象-目标的新型国有企业三维监管机制模型,从经营者监管、重大事项监管及国有资产监管3种监管对象的角度,展开详细的理论分析,以试图详尽阐述新型国有企业三维监管机制的内在运行机理。     

Explosive nucleosynthesis in stars

Recent calculations provide convincing evidence that the naturally occurring nuclei were produced in explosions. The required temperature, density and expansion rate strongly suggest that before the explosion the objects were ordinary evolved massive stars. We review these new developments and present a new table indicating our hypothesis concerning the origin of the nuclei in the mass range 20 < or = A < or = 62.     

元素核合成理论

在星际演化过程中 ,通过热核聚变和中子俘获等核反应 ,合成了氢、氦直到原子序数为 92的铀的所有原子核。本文简单介绍元素核合成的 8种核反应过程。     

量子系综对的量子关联性

研究一对量子系综{ε,η}的量子关联性。在量子信息论中,通过量子测量只能知道量子系统的状态ρ以一定的概率pi处于某个状态ρi,从而得到一系列的量子态ρ1,ρ2,…,ρn以及它们出现的相应概率p1,p2,…,pn;进而得到一个量子系综ε={pi,ρi}ni=1。构造一个四体量子态ρε,η,利用量子相对熵,定义了反映量子系综对所含量子关联的度量函数,揭示了这个度量函数的一些性质。     

两相邻Said-Ball曲线的近似合并

利用Said-Ball基函数和Bernste in基函数之间的关系,结合两相邻Béz ier曲线的近似合并方法,给出两相邻Said-Ball曲线的近似合并方法。该法有以下特点:(1)可直接得到合并曲线的控制顶点,(2)不论待合并的两相邻曲线的次数是否相同,均可直接合并,(3)不需对原曲线进行升阶变换,直接提高合并曲线的次数,就可以得到更高阶的合并曲线。在合并过程中,考虑了合并曲线在左右端点处与原曲线达到高阶插值的合并。最后给出数值例子。     

Binary Sequences from a Pair of Elliptic Curves

A family of binary sequences were constructed by using an elliptic curve and its twisted curves over finite fields. It was shown that these sequences possess ＂good＂ cryptographie properties of 0-1 distribution, long period and large linear complexity. The results indicate that such se quences provide strong potential applications in cryptography.     

相对论磁化等离子体二体关联动力方程的格林函数

应用二体关联动力方程的格林函数方法，算出了相对论磁化等离子体中点源粒子产生的诱发电场和扰动分布函数。     

Determination of the fermion pair size in a resonantly interacting superfluid

Fermionic superfluidity requires the formation of particle pairs, the size of which varies from the femtometre scale in neutron stars and nuclei to the micrometre scale in conventional superconductors. Many properties of the superfluid depend on the pair size relative to the interparticle spacing. This is expressed in 'BCS-BEC crossover' theories, describing the crossover from a Bardeen-Cooper-Schrieffer (BCS)-type superfluid of loosely bound, large Cooper pairs to Bose-Einstein condensates (BECs) of tightly bound molecules. Such a crossover superfluid has been realized in ultracold atomic gases where high-temperature superfluidity has been observed. The microscopic properties of the fermion pairs can be probed using radio-frequency spectroscopy. However, previous work was difficult to interpret owing to strong final-state interactions that were not well understood. Here we realize a superfluid spin mixture in which such interactions have negligible influence and present fermion pair dissociation spectra that reveal the underlying pairing correlations. This allows us to determine that the spectroscopic pair size in the resonantly interacting gas is 20 per cent smaller than the interparticle spacing. These are the smallest pairs so far observed in fermionic superfluids, highlighting the importance of small fermion pairs for superfluidity at high critical temperatures. We have also identified transitions from fermion pairs to bound molecular states and to many-body bound states in the case of strong final-state interactions.     

关于一对宏观经济优化模型的进一步讨论

本文通过对文[1]所建立的政府追求社会福利最大化和资源消耗最小化两个宏观经济优化模型的进一步讨论,得到了一个关于模型解的并有着较好经济解释的定理,并且指出了政府所寻求的既能保证效率又能兼顾公平的政策方案关键在于社会福利函数的设计,同时也与模型给定的常数系有着密切的关系。     

具有一对零同态的Morita context环

通过引入偏序模对的定义,给出了在交换环上Morita Context环T为VNL环的一个充要条件;对Morita Context环为左Quasi-duo环、DS环以及左Quasi-morphic环的性质进行了刻画.     

关于映象对的某些不动点定理

本文建立了完备2—距离空间的两个不动点定理,另一个在完备度量空间的类似结果也被建立,它是文献[1]的主要结果的推广。     

单自由度齿轮系统非线性动力学特性分析

建立了综合考虑齿侧间隙、时变啮合刚度、综合啮合误差等因素的直齿轮副的单自由度非线性动力学模型,利用变步长Runge-Kutta法对单自由度运动微分方程进行数值求解.结合系统的分岔图、相图、Poincaré映射图以及FFT频谱图,分析了系统在不同侧隙值下,阻尼比变化时的动力学特性,得到了系统的混沌运动形成过程.     

一种立体视觉图像的特征选择与匹配方法

从立体图像对中获取精确的三维信息需要进行相机建模、标定和图像点的匹配［１，２］．提出了特征点的选取；利用金字塔图像结构进行立体匹配，以及对匹配点进行整体性检验的准则。实验表明，该算法匹配速度快，错误概率小，匹配点在整个景物中分布均匀。     

扩张型映射对的公共不动点定理

在王尚志等人讨论的几类扩张映射的不动点问题的基础上,研究了完备度量空间中几类扩张型映射对的公共不动点的存在性与惟一性.另外,还对夏大峰讨论的压缩型映射对的相反情况：满足某函数的扩张型映射对的公共不动点存在性定理作了探讨.改进了王尚志、夏大峰等的一些主要结果.