基于旋量理论的开链机器人动力学Kane方程研究

首先介绍了旋量的基本理论、指数积及雅可比矩阵．在此基础上定义了基于旋量理论的主动力旋量、惯性力旋量、偏速度旋量、广义主动力及广义惯性力等概念,之后推导出了基于旋量理论的开链机器人动力学Kane方程,再者阐明了偏速度旋量几何计算,最后以示例验证结论的正确性．     

Comparison of the structures of 1,5-dichloro- and 1,5-dibromonaphthalene-2,6-diol and their co-crystalline compounds with dioxane

The 1,5-dichloro-(1) and 1,5-dibromo-(2) naphthalene-2,6-diols form isostructural lattices incorporating ...O–H...O–H...O–H... hydrogen bonding surrounding 2₁ screw axes. Each phenolic hydroxy group participates in one donor and one acceptor hydrogen bond. When crystallised from dioxane, both compounds form new 1:1 co-crystalline materials whose lattices are closely related but not isostructural. All inter-phenolic hydrogen bonding is now absent with each hydroxy group acting instead as a donor to a dioxane oxygen atom. In consequence, the hydrogen bonded layer structures of pure1 or2 are now replaced by hydrogen bonded chain arrangements. All four crystal structures are analysed and compared in crystal engineering terms through discussion of the various types of other weak intermolecular attractions involved in their lattice constructions. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82202 (19 pages).     

M(o)bius环并苯的分子对称性

一般来说,点群理论认为M(o)bius带环分子最高的对称性只能是C2.本文讨论了由18个苯环组成的环并苯的异构体分子,包括柱面的Hückel型分子(HC-[18])和扭转180°的M(o)bius带环分子(MC-[18]).结果表明除了点对称性外,M(o)bius带环分子还存在一种可称为环面螺旋旋转(TSR)变换的对称性,为此还引用了环面正交曲线坐标系.此外,还讨论了这些分子关于TSR对称性匹配的原子集和原子轨道(AO)集.根据TSR对称性的循环群特征,可以建立此类群的不可约表示及有关特征标.这类分子的分子轨道(MO)关于TSR群的不可约表示是纯的,然而所含的相应的原子轨道对称性匹配的线性组合(SALC-AO)成分可以是多种的.     

Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly (Lactide)

Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results provided a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measurement of PLA stated that the best combination of factors (levels) was the following: matrix (s-DHB), proportion analyte/matrix (1/5 V/V), and no use of cationization agent. Degradation primarily affected the initially predominant cyclic [LA_C]_n and linear H[LA_L]_nOH species, where LA stands for a PLA repeating unit. Intramolecular and intermolecular transesterifications as well as hydrolytic and homolytic reactions took place during the formation and disappearance of oligomeric species. In both degradation mechanisms induced by thermal ageing and thermo-mechanical degradation, the formation of H[LA_L]_nOCH₃ by intermolecular transesterifications was highlighted.     

The size‐Ramsey number of trees

Given a graph G, the size‐Ramsey number $\hat r(G)$ is the minimum number m for which there exists a graph F on m edges such that any two‐coloring of the edges of F admits a monochromatic copy of G. In 1983, J. Beck introduced an invariant β(·) for trees and showed that $\hat r(T) = \Omega (\beta (T))$ . Moreover he conjectured that $\hat r(T) = \Theta (\beta (T))$ . We settle this conjecture by providing a family of graphs and an embedding scheme for trees. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011     

A moving piezoelectric screw dislocation

A moving screw dislocation in a transversely isotropic piezoelectric material is investigated in detail. The analytical expressions for displacement, electric potential, stresses, electric displacements, strains, and electric fields are obtained. When the velocity of the dislocation is zero, or when the piezoelectric constant is zero, the results derived in this paper can reduce to known results.     

长寿命斯特林制冷机膨胀机无摩擦运行技术

论述了长寿命斯特林制冷机膨胀机的结构,重点对排出器活塞与冷指气缸无接触运行控制方法进行论述.制冷机正在进行加速寿命跑和,运行很好.     

Φ0300激光扩束器光学系统设计

从三级像差理论出发,分析伽里略(Galilean)和开卜勒(Keplerian)两种类型扩束器的轴外像差没有得到很好校正的原因·通过合理的光路分析,设计出一种轴上和轴外像差都得到很好校正、大口径大相对孔径、视场可增大的、光学性能优于伽里略和开卜勒扩束器的新型扩束器·并给出了物镜通光口径为300mm、物镜焦距为800mm、视场为4mrad、放大倍率为30倍、主工作波长为0.6328μm的非球面扩束器光学系统结构参量,且进行了像质评价·调整此扩束器目镜组中各镜片的间隔以及物镜和目镜的间隔可以使该扩束器在三个波长使用·     

Magneto-optical specifications of Rosen-Morse quantum dot with screw dislocation

This is the first study to consider a quantum dot with screw dislocation that has Rosen-Morse (RM) confinement potential, generated by a GaAs/GaAlAs heterostructure. An external magnetic field and Aharonov-Bohm (AB) flux field were also applied on RM quantum dot (RMQD) in order to stave the effects of a screw dislocation defect. The combined effect of the screw dislocation defect, the external magnetic field, and AB flux field on the total refractive index changes (TRICs) and the total absorption coefficients (TACs) of RMQD are thus investigated. Cylindrical coordinates are used due to the direction of application of the torsion and the external fields, as well as due to the structure's symmetry. The effective mass approximation and tridiagonal matrix methods are used in order to obtain the subband energy spectra and electronic wave functions of RMQD. The nonlinear optical specifications of RMQD are checked using compact-density-matrix formalism within the framework of the iterative method. Reviews without screw dislocation are also carried out in order to be able to clarify the effects of a screw dislocation defect on the optical properties, and then, both cases are deliberated. This study is the first attempt to analyze the AB flux field for RMQD without screw dislocation. In the present study, the influences of a screw dislocation defect on RMQD's TRICs and TACs are probed by considering different values of the external magnetic field and AB flux field, and the ranges of corresponding parameters on the optimum of the structure are specified. Moreover, the study also elucidates how to rule out the effects of screw dislocation on optical specifications by means of the external fields. Despite a certain screw dislocation, the frequency range is determined where the structure behaves as if it is perfect (namely, without screw dislocation) for its optimum, which in turn is crucial for experimental applications.     

低温旋转阀脉冲管制冷机实验研究

本文讨论了一种可适用于气体液化的新型脉冲管制冷系统：在该系统中,回热器被间壁式换热器所取代。切换阀置于脉冲管冷端,和脉冲管作为一个整体,起气体膨胀机的作用。我们建立了相应的实验装置以测量整个系统的性能．利用空气作介质,系统进出口温降为６３．６Ｋ,绝热膨胀效率可达４２％。利用氦气作工质,脉冲管冷端最低温度达１６０Ｋ,每１Ｋ有０．７５Ｗ的制冷量。