用边界轮廓法求解断裂力学L积分

证明断裂力学Ｌ积分方程的被积函数的散度等于零,将面积分转化为线积分,使求解问题的维数降低两维。利用边界轮廓法的结果,使平面断裂问题Ｌ积分的求解转化为边界点的位移和面力线性迭加,避免了求解数值积分。     

Subnanosecond switching, plasma electrode pockels cell for high-contrast imaging with partially coherent light

A high-contrast optical switch for imaging partially coherent light (~150 times the diffraction limit) requires that it have a large angular acceptance. We describe the development of a high-speed Pockels cell that uses a thin crystal to simultaneously achieve high-contrast (greater than 1800:1) and large-angular acceptance (greater than 7 mrad for a 5-mm aperture). A KD*P crystal was used in a longitudinal-mode configuration with plasma discharges forming low-resistance, high optical transmission electrodes to couple the switching voltage. Rise times of the switched optical pulse of the order of 500 ps were observed. Characterization of the device in the near and far fields was also performed.     

动态优化调度走向实用的策略与段落全局优化

本文在总结动态优化调度在实际系统中应用经验的基础上,提出了动态优化调度走向实用的策略及以段落一局优化算动态化调度的方法,该策略可以较地贯彻电力系统运行“安全,优质,经济”的原则,段落全局优化方法则可以一次性处理各种负荷紧段落,包括单调升降段落及以往方法只有通过反向导引才能够处理的陡升连续等类的段落,具有计算时间短,节省内存等特点,为动态优化调度在电力系统中的进一步实用化打下了坚实的基础。     

Nanoconfinement induced anomalous water diffusion inside carbon nanotubes

The diffusion mechanism and coefficient of water confined in carbon nanotubes (CNTs) of diameter ranging from 8 to 54 ? are studied by molecular dynamics simulations. It is found that the motions of water molecules inside the CNTs of diameter smaller than 12.2 ? follow a two-stage diffusion mechanism. Initially, the water diffusion exhibits a long-time super- or sub-diffusion mechanism, and thereafter it transits to the single-file type inside the (6, 6) CNT and shifts to the Fickian type inside the larger CNTs. As for the CNTs of diameter larger than 12.2 ?, the diffusion of the confined water occurs through the Fickian mechanism, which is identical to that of the bulk water. The simulation results further reveal that the diffusion coefficient of the confined water is non-monotonically dependent on the diameter, which can be ascribed to the double-edged effect of CNTs, i.e., the surface effect and the size effect.     

Dual-key-binding cancelable palmprint cryptosystem for palmprint protection and information security

Biometric cryptosystems and cancelable biometrics are both practical and promising schemes to enhance the security and privacy of biometric systems. Though a number of bio-crypto algorithms have been proposed, they have limited practical applicability because they lack of cancelability. Since biometrics are immutable, the users whose biometrics are stolen cannot use bio-crypto systems anymore. Cancelable biometric schemes are of cancelability; however, they are difficult to compromise the conflicts between the security and performance. By embedded a novel cancelable palmprint template, namely “two dimensional (2D) Palmprint Phasor”, the proposed palmprint cryptosystem overcomes the lack of cancelability in existing biometric cryptosystems. Besides, the authentication performance is enhanced when users have different tokens/keys. Furthermore, we develop a novel dual-key-binding cancelable palmprint cryptosystem to enhance the security and privacy of palmprint biometric. 2D Palmprint Phasor template is scrambled by the scrambling transformation based on the chaotic sequence that is generated by both the user's token/key and strong key extracted from palmprint. Dual-key-binding scrambling not only has more robustness to resist against chosen plain text attack, but also enhances the secure requirement of non-invertibility. 2D Palmprint Phasor algorithm and dual-key-binding scrambling both increase the difficulty of adversary's statistical analysis. The experimental results and security analysis confirm the efficiency of the proposed scheme.     

Numerical solution of PDEs via integrated radial basis function networks with adaptive training algorithm

This paper develops a mesh-free numerical method for solving PDEs, based on integrated radial basis function networks (IRBFNs) with adaptive residual subsampling training scheme. The multiquadratic function is chosen as the transfer function of the neurons. The nonlinear algebraic equation systems for weights training are solved by Levenberg–Marquardt algorithm. The performance of the proposed method is demonstrated in numerical examples by approximating several functions and solving nonlinear PDEs. The result of numerical experiments shows that the IRBFNs with the adaptive procedure requires less neurons to attain the desired accuracy than conventional radial basis function networks.     

Bayesian projection approaches to variable selection in generalized linear models

A Bayesian approach to variable selection which is based on the expected Kullback-Leibler divergence between the full model and its projection onto a submodel has recently been suggested in the literature. For generalized linear models an extension of this idea is proposed by considering projections onto subspaces defined via some form of L₁ constraint on the parameter in the full model. This leads to Bayesian model selection approaches related to the lasso. In the posterior distribution of the projection there is positive probability that some components are exactly zero and the posterior distribution on the model space induced by the projection allows exploration of model uncertainty. Use of the approach in structured variable selection problems such as ANOVA models is also considered, where it is desired to incorporate main effects in the presence of interactions. Projections related to the non-negative garotte are able to respect the hierarchical constraints. A consistency result is given concerning the posterior distribution on the model induced by the projection, showing that for some projections related to the adaptive lasso and non-negative garotte the posterior distribution concentrates on the true model asymptotically.     

物位计测量技术分析及应用研究

雷达物位技术是物位测量技术中发展较快的技术之一,但我国雷达物位仪表的研发还比较落后。分析了雷达物位计市场所占比重最大的两种测量方式——雷达脉冲测量和连续波线性调频测量的信号处理方式,比较了它们各自的优缺点,并指出了在应用中应注意的问题;同时,探讨了物位计开发过程中的技术难点,并根据我国现有的技术条件提出了相应的解决方案。