Modulation of Spin Distribution and Spin Transport by a Magnetic Field in a Quasi-One-Dimensional System with Spin--Orbit Coupling

The distributions of spin and currents modulated by magnetic field in a transverse parabolic confined two-dimensional electronic system with a Rashba spin--orbit coupling have been studied numerically. It is shown that the spin accumulation and the spin related current are generated by magnetic field if the spin--orbit coupling is presented. The distributions of charge and spin currents are antisymmetrical along the cross-section of confined system. A transversely applied electric field does not influence the characteristic behaviour of charge- and spin-dependent properties.     

Novel construction of the brassinolide side chain

A stereoselective synthesis of brassinolide, which involves construction of the side chain by a highly stereoselective aldol reaction between 20S-6β-methoxy-3α,5-cyclo-5α-pregnane-20-carboxaldehyde 2 and ketone 3 or 4 catalyzed by l-proline, is described.     

能动抛光磨盘的变形实验研究

 能动抛光磨盘实时产生不同的表面变形，在对大口径非球面光学元件进行精磨和抛光时实现与工件表面良好的大尺寸吻合，可以消除传统光学加工采用小尺寸磨头时带来的高频残余误差并提高加工效率。以加工直径1.3m左右，F/2的抛物面光学元件为例，对能动磨盘在不同离轴度时能够产生的变形进行了计算和实验。结果表明，能动磨盘能够以较高精度产生旋转对称或非对称的抛物面形状。对能动磨盘产生变形后的残余误差进行了分析。     

埋地热油管道正常运行的数值模拟研究

对高凝原油管道输送的水力热力问题进行分析研究,掌握管线运行规律,保证管线安全经济运行有着重要意义.本文建立了埋地热油管道正常运行的数学模型,采用非结构化网格和有限容积法对该问题进行了研究,计算结果与实验测量值吻合良好.     

Cytotoxic and NF-κB inhibitory sesquiterpene lactones from Piptocoma rufescens

Six new (1-6) and eight known germacranolide-type sesquiterpene lactones, along with several known phenylpropanol coumarates and methylated flavonoids, were isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. The new compounds were identified by analysis of their spectroscopic data, with the molecular structure of 3 being established by single-crystal X-ray diffraction. The absolute configurations of the sesquiterpene lactones isolated were determined from their CD and NOESY NMR spectra, together with the analysis of Mosher ester reactions. Bioassay screening results showed the majority of the sesquiterpene lactones isolated (1-13) to be highly cytotoxic toward the HT-29 human colon cancer cell line, with the most potent compound being 15-deoxygoyazensolide (10, IC(50), 0.26 μM). In addition, several of the sesquiterpene lactones exhibited NF-κB (p65) inhibitory activity.     

基于隐马尔科夫模型的汉语韵律词基频模型

提出了一种基于隐马尔科夫模型(HMM)的汉语韵律词的统计基频模型。模型能反映韵律环境和基频曲线参数之间的映射关系,从模型可以估计一段基频曲线和一段文本之间的相关度,也可以从文本生成相应的基频曲线。本方法使用HMM作为基木框架,具有HMM理论体系所能支配的各种优点。同时将韵律作为模型单元,使得模型能够反映韵律层次级的连续变调。最后给出了实验结果并对模型的应用前景进行了展望。     

α-decay study of 218Ac and 221Th in 40Ar+186W reaction

In this study,²¹⁸Ac and ²²¹Th nuclides were produced via the heavy-ion induced fusion evaporation reaction ⁴⁰Ar+¹⁸⁶W.Their decay properties were studied with the help of the gas-filled recoil spectrometer SHANS and a digital data acquisition system.The cross section ratio between ²²²Pa and ²¹⁸Ac was extracted experimentally,withmeasured value 0.69(9).Two new possible α decay branches to ²²¹Th are suggested.The valence neutron configurations for the daughter ²¹⁷Ra are discussed in terms of the hindrance factors.     

最大均方差异统计量的一般界

经典的最大均方差异统计量MMDb(F,X,Y)和MMD2u(F,X,Y)基于等量假设(即m=n)来检验两组样本X={x1,x2,…,xm}和Y={y1,y2,…,yn}是否来自不同的分布.本文对样本等量假设进行了放松,推广了经典的最大均方差异统计量界,推导出当m≠n时统计量MMDb(F,X,Y)和MMD2u(F,X,Y...     

The Applications of Order Reduction Methods in Nonlinear Dynamic Systems

Two different order reduction methods of the deterministic and stochastic systems are discussed in this paper. First, the transient proper orthogonal decomposition (T-POD) method is introduced based on the high-dimensional nonlinear dynamic system. The optimal order reduction conditions of the T-POD method are provided by analyzing the rotor-bearing system with pedestal looseness fault at both ends. The efficiency of the T-POD method is verified via comparing with the results of the original system. Second, the polynomial dimensional decomposition (PDD) method is applied to the 2 DOFs spring system considering the uncertain stiffness to study the amplitude-frequency response. The numerical results obtained by the PDD method agree well with the Monte Carlo simulation (MCS) method. The results of the PDD method can approximate to MCS better with the increasing of the polynomial order. Meanwhile, the Uniform-Legendre polynomials can eliminate perturbation of the PDD method to a certain extent via comparing it with the Gaussian-Hermite polynomials.