对双生子佯谬问题的几种解释

给出备受物理学界关注的双生子佯谬问题的几种探讨。首先给出最一般的讨论,即完全利用狭义相对论中的洛仑兹变换,计算出具体实例中留守者和旅行者各自所经历的时间,并进行比较。计算中,旅行者发现留守者的时间突增是解决问题的关键所在。其次,利用几何方法对双生子佯谬进行解释,即利用闵氏时空图对其进行解释,这里包含了一个重要结论:闵氏时空中的类时测地线为最长类时线。文中最后将深入地分析双生子佯谬的物理机制。看似对称的双生子运动实则并不对称,旅行者是有加速过程的,其加速度大小和加速期长短对其时间延缓是有影响的。这也是对前面提到的产生时间突增的原因的补充说明。讨论结果表明:双生子佯谬实质上并不是佯谬,而是一个绝对效应。     

Formation of drug-loaded electrospun twin fibers

Electrospinning is a well-known process for producing submicrometer fibers, which have wide applications in many fields, especially in tissue engineering scaffolds and drug-delivery systems. This paper presents the formation of drug-loaded electrospun twin fibers. The correlations between the twin fiber formation and the polymer materials or the loaded drugs were studied by using poly(l-lactide) and poly(l-lactide-co-glycolide) as electrospinning materials, and rifampin and paclitaxel as loaded drugs. Scanning electron microscopy showed that the formation of twin fibers is significantly affected by the loaded drug but not the polymer material. A possible reason for twin fiber formation was analyzed.     

关于孪生素数猜想的一个证明

以建立筛状结构(构形)列为切入点,根据其内在性质和构形间的相互关系得出构形中孤立态元素个数以及相邻数对个数的公式,从而证明了孪生素数对是无限多的结论.     

Sonography: dizygotic twin survival in early pregnancy

It has been suggested that losses of twin conceptuses in very early pregnancy are high, and that for every liveborn twin pair there are a further 10-12 twin pregnancies that end up as a singleton birth. Here we show that in a group of women who had double-ovulated and conceived, the probability of the second egg also becoming fertilized and developing is 20-30% - which is comparable to the probability of conception and survival of a single conceptus. We conclude that the presence of one embryo does not affect the development of its twin.     

孪生素数有无穷多个的一个证明

运用一种新的筛法,筛去较小的孪生素数和不满足孪生素数条件的数,运用初等数学的方法,证明其有无穷多个,从而证明了孪生素数有无穷多个.且给出了孪生素数分布的一个规律,即对于一切素数p,在任何两个相邻素数平方的区间[[2i,p2i＋1]上,至少有一组孪生素数.此方法还可以用于其他素数间隔是否为无限个的判断和证明以及分布规律的研究.     

双卧轴搅拌机叶片排列的试验

根据双卧轴混凝土搅拌机内物料运动的特点,分析了搅拌叶片不同排列方式对混凝土搅拌质量的影响,得出了搅拌叶片的合理排列方式,并进行了试验验证。结果表明:搅拌叶片的排列应保证物料在整个拌筒空间内循环流动,以及在中央主搅拌区内最大限度的逆流运动;搅拌叶片的最佳排列方式为正反排列。     

最小二乘双胞支持向量回归机的研究

 利用最小二乘方法和临近支持向量机(PSVM)算法,并结合双胞支持向量机(TSVR),提出了最小二乘双胞支持向量回归机(LSTSVR).作为对照,TSVR需要求解2个二次规划问题,而LSTSVR仅需求解2个线性方程组.最后利用不同的实例验证了所提算法的可行性和有效性.