铺砌中椭圆上D-点数的研究

阿基米德平面铺砌是指用一种或多种正多边形铺砌全平面,且要求铺砌的每个顶点的顶点特征相同。阿基米德平面铺砌共有11种,针对其中的[4.8.8]铺砌,即每个铺砌顶点连接边长相同的一个正方形,两个正八边形,研究[4.8.8]铺砌上的椭圆所包含铺砌顶点数的特性,通过对椭圆内半弦上顶点列的分析,采用数的几何及数论中同余的方法给出顶点数的取值算法,并获得顶点数与椭圆短半轴长平方的比值的极限公式,证明极限值与对应铺砌的中心多边形的面积有关。所得算法及极限公式对其他阿基米德铺砌中相关问题的研究有借鉴作用。     

两性霉素B合成基因簇及其组合生物学进展

 两性霉素B（AmB）作为第一个用于深部真菌感染的药物,自上市以来已使用超过半个世纪,目前仍是临床治疗中不可缺少的药物。随着近年来AmB衍生物药物的发展,以及其生产菌株结节链霉菌（Streptomyces nodosus）全基因组和AmB体内合成代谢途径的解析,运用基因工程和代谢工程的方法对AmB组合生物合成的研究逐渐增多。由于AmB在当今临床治疗上的地位仍极其重要,因此促进AmB产业的发展具有显著的经济及社会效益。本文对AmB进行了概述,并对其合成基因簇相关基因及其当前组合生物合成的研究现况进行了总结与探讨。     

13-14岁学生思维的发展与平面几何的学习

13—14岁学生的思维是由经验型抽象思维向理论型抽象思维发展的关键期,也是了解对立统一的辨证思维规律的开始。平面几何是培养学生严格推理论证能力的最佳载体,借助平面几何的概念、语言和图形学习,建构学生合理的中学数学的认知结构,促使学生的思维能力在关键期得到有效发展。     

微通道铣削加工工艺的实验研究

为了实现微通道的高效加工,提出利用微细铣刀对铝合金薄板进行微通道阵列结构加工,并通过改变加工工艺参数的方法,系统研究了铣削加工参数(背吃刀量、进给速度和主轴转速)对微通道的几何尺寸的影响规律。研究结果表明:选用直径为0.4mm铣刀的条件下,加工出微通道的宽度随着背吃刀量和进给速度的增大而逐渐增大,且背吃刀量的影响较为明显。在6 000~21 000r/min的主轴转速范围内,随着主轴转速的增加,微通道的宽度尺寸变化不大。因此,通过选择优化的切削加工工艺参数,可以实现微通道阵列结构的加工。     

由二阶矩阵推导组合恒等式

设二阶矩阵A=(abcd),得到矩阵A的n次幂中的元素a11,a12,a 21,a22与a,b,c,d之间关系式.给出a,b,c,d一些特殊值,根据恒等式(An)2=A 2n和(An)3=A3n,得到一些有趣的组合恒等式。     

SGARP中全角法的实现

在可持续发展的几何自动推理平台SGARP中，通过添加全角法相关的对象、谓词和定理，在SGARP中成功实现了全角法。添加了全角法的SGARP测试证明了100个几何定理。     

快速生成两两组合测试用例集算法

研究了二元待测系统的最优二维覆盖表的构造,在此基础上提出了快速生成一般待测软件系统的二维覆盖表的算法.该算法首先针对二元待测系统生成相应的基本块B(0,1)和约简块R(0,1),然后对任意的取值组合对(a,b),通过替换生成相应的基本块B(a,b)或约简块R(a,b),最后累加所有的块得到二维覆盖表.因此当待测系统是二...     

PFD-SMA支撑体系的抗震性能

对传统的Pall摩擦阻尼支撑体系进行改进,提出一种PFD-SMA支撑体系,充分利用Pall摩擦阻尼器(PFD)和形状记忆合金(SMA)的优点,使该体系具有强耗能能力和自复位功能;考虑几何非线性采用ANSYS程序对SMA棒材和PFD-SMA体系进行分析。研究结果表明:SMA棒材具有较强的耗能能力,且可恢复应变大;在钢框架结构中采用PFD-SMA体系能有效降低结构的地震响应,提高结构的抗震性能,同时,该体系可通过形状记忆超弹性及形状记忆效应具有双重自复位功能,表明PFD-SMA体系具有良好的抗震性能。     

局部应力场中表面裂纹的线弹簧模型分析

线弹簧被用以模拟考虑局部几何形状的边裂纹板条,由有限元方法,结合Ｔ型板架结构进行了实例分析．     

Space–time philosophy reconstructed via massive Nordström scalar gravities? Laws vs. geometry,conventionality, and underdetermination

What if gravity satisfied the Klein–Gordon equation? Both particle physics from the 1920–30s and the 1890s Neumann–Seeliger modification of Newtonian gravity with exponential decay suggest considering a “graviton mass term” for gravity, which is algebraic in the potential. Unlike Nordström׳s “massless” theory, massive scalar gravity is strictly special relativistic in the sense of being invariant under the Poincaré group but not the 15-parameter Bateman–Cunningham conformal group. It therefore exhibits the whole of Minkowski space–time structure, albeit only indirectly concerning volumes. Massive scalar gravity is plausible in terms of relativistic field theory, while violating most interesting versions of Einstein׳s principles of general covariance, general relativity, equivalence, and Mach. Geometry is a poor guide to understanding massive scalar gravity(s): matter sees a conformally flat metric due to universal coupling, but gravity also sees the rest of the flat metric (barely or on long distances) in the mass term. What is the ‘true’ geometry, one might wonder, in line with Poincaré׳s modal conventionality argument? Infinitely many theories exhibit this bimetric ‘geometry,’ all with the total stress–energy׳s trace as source; thus geometry does not explain the field equations. The irrelevance of the Ehlers–Pirani–Schild construction to a critique of conventionalism becomes evident when multi-geometry theories are contemplated. Much as Seeliger envisaged, the smooth massless limit indicates underdetermination of theories by data between massless and massive scalar gravities—indeed an unconceived alternative. At least one version easily could have been developed before General Relativity; it then would have motivated thinking of Einstein׳s equations along the lines of Einstein׳s newly re-appreciated “physical strategy” and particle physics and would have suggested a rivalry from massive spin 2 variants of General Relativity (massless spin 2, Pauli and Fierz found in 1939). The Putnam–Grünbaum debate on conventionality is revisited with an emphasis on the broad modal scope of conventionalist views. Massive scalar gravity thus contributes to a historically plausible rational reconstruction of much of 20th–21st century space–time philosophy in the light of particle physics. An appendix reconsiders the Malament–Weatherall–Manchak conformal restriction of conventionality and constructs the ‘universal force’ influencing the causal structure.Subsequent works will discuss how massive gravity could have provided a template for a more Kant-friendly space–time theory that would have blocked Moritz Schlick׳s supposed refutation of synthetic a priori knowledge, and how Einstein׳s false analogy between the Neumann–Seeliger–Einstein modification of Newtonian gravity and the cosmological constant Λ generated lasting confusion that obscured massive gravity as a conceptual possibility.