双边缘技术多普勒测风激光雷达标准具的优化

 优化了基于双边缘技术的直接测风多普勒激光雷达中F-P标准具的工作参数。确定激光谱宽后，选择适当的F-P标准具自由谱间距，可正确消除瑞利背景噪声的影响。分析了标准具镜面缺陷、非严格平行和入射光束发散角对其透过率曲线的影响。将标准具透过率函数表达为唯一系统参数，即反射精细度的函数；通过计算散粒噪声极限时的相对测量误差，可确定最优反射精细度以及激光频率相对标准具透过率中心频率的最佳偏置；由最优反射精细度可得到入射到标准具光束的最大发散角和标准具的最小通光口径。     

Dynamics and control of an active pendulum system

The work focuses on autoparametric vibrations of system composed of a non-linear oscillator with an attached pendulum. A combination of semi-active damper together with a non-linear spring mounted in the suspension of system is proposed. The spring is made from a shape memory alloy (SMA) while damping is realized through a magnetorheological (MR) damper. The MR damper is used for controlling damping of the system, SMA spring is used to change system׳s stiffness. The system is solved numerically and verified experimentally on a custom made experimental rig. Specifically, non-linear resonances are investigated, and their influence on the system dynamics and absorption effect.     

Spectral assessment of mesh adaptations for the analysis of the dynamical longitudinal behavior of railway bridges

Summary  Extensive studies, [1], concerning the longitudinal behavior of long railway bridges due to braking forces have been done by measurements in situ, [2], and by statical, [3, 4], as well as dynamical simulations. Thereby, the only consistent numerical realization with respect to the measured data was the dynamical one. However, the consecutive discretizations in space and time with time-dependent system matrices are extremely time consuming due to the moving loads and varying stiffness of the ballast under, and in front of, the moving train. Therefore, every effort should be made to optimize the discretization in the space domain. This paper presents a strategy for assessing the quality of finite elements in space and for applying an adaptive mesh-refinement for this special engineering problem. The method is characterized by a spectral assessment, comparing a certain set of eigenvalues of the actual discretization with those of a very fine and rather exact numerical model. The error estimator introduced in this paper controls a whole set of global eigenvalues with corresponding natural vibration modes in order to assess certain types of shape functions. Thus, the procedure estimates local modifications on the one hand and p-properties on the other by means of global indication. Received 30 August 1999; accepted for publication 26 September 2000     

Universal duality in conic convex optimization

Given a primal-dual pair of linear programs, it is well known that if their optimal values are viewed as lying on the extended real line, then the duality gap is zero, unless both problems are infeasible, in which case the optimal values are +∞ and −∞. In contrast, for optimization problems over nonpolyhedral convex cones, a nonzero duality gap can exist when either the primal or the dual is feasible. For a pair of dual conic convex programs, we provide simple conditions on the ``constraint matrices' and cone under which the duality gap is zero for every choice of linear objective function and constraint right-hand side. We refer to this property as ``universal duality'. Our conditions possess the following properties: (i) they are necessary and sufficient, in the sense that if (and only if) they do not hold, the duality gap is nonzero for some linear objective function and constraint right-hand side; (ii) they are metrically and topologically generic; and (iii) they can be verified by solving a single conic convex program. We relate to universal duality the fact that the feasible sets of a primal convex program and its dual cannot both be bounded, unless they are both empty. Finally we illustrate our theory on a class of semidefinite programs that appear in control theory applications. This work was supported by a fellowship at the University of Maryland, in addition to NSF grants DEMO-9813057, DMI0422931, CUR0204084, and DoE grant DEFG0204ER25655. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the National Science Foundation or those of the US Department of Energy.     

一种高效的优化量子Monte Carlo波函数的新方法

提出了一个优化量子MonteCarlo波函数的新方法，与前人的方法相比，它不使用变分原理而是极小化Schrodinger方程的剩余量；不按Ψ2取样而是按Ψ2（EL－E）2取样；不用差分而是用分析导数；不使用传统的速降法而是使用一个步长自动调节的下降法，它具有拟牛顿性质，因而是超线性收敛的．由于这四项新技术的使用，使得波函数的优化快速、准确，收敛速度比前人提出的方法快3～5倍．     

A method for globally minimizing concave functions over convex sets

A method is described for globally minimizing concave functions over convex sets whose defining constraints may be nonlinear. The algorithm generates linear programs whose solutions minimize the convex envelope of the original function over successively tighter polytopes enclosing the feasible region. The algorithm does not involve cuts of the feasible region, requires only simplex pivot operations and univariate search computations to be performed, allows the objective function to be lower semicontinuous and nonseparable, and is guaranteed to converge to the global solution. Computational aspects of the algorithm are discussed.     

Risk-adjusted control charts for health care assessment

The recent Joint Commission on Accreditation of Healthcare Organization (JCAHO) requirement that hospital accreditation be based upon a Total Quality Management (TQM) approach has focused the attention of health care administrations on the use of techniques such as control charts. However, control charts are not typically adjusted for severity of illness. This adjustment is needed because, unlike industrial organizations, hospitals are not able to control all of their inputs and must accept variances in their patients. In this paper, we present a methodology for adjusting a health care organization's control charts to reflect their patient population's severity of illness during different time intervals. We then demonstrate that risk-adjusting expected patient outcomes can change our assessments of the relative quality of care offered by a health care organization in different time periods.     

Development of an Automated Procedure for the Optimization of Multielement Analysis with Energy Dispersive X-Ray Fluorescence Spectroscopy

Abstract

A system is devised that automatically optimizes energy dispersive x-ray spectrometer settings for multielement determinations under compromise conditions using self-sustained search algorithms. As an objective function, the joint probability of detecting all elements was chosen. The current process is to date limited by the resolution of the commercially available automatic power supply employed. Typical optimization times needed for the entire procedure are on the order of 5 minutes for major constituents, with prolonged times for minor and trace elements as a result of increased counting time to obtain good counting statistics.     

Optimization of GaAs semiconductor saturable absorber Q-switched lasers

The expressions of pulse characteristics such as output energy, peak power, and pulse width are obtained by solving the coupled rate equations describing the operation of GaAs semiconductor saturable absorber Q-switched lasers. The key parameters of an optimally coupled GaAs saturable absorber Q-switched laser are determined and several design curves are generated from these expressions for the first time. These key parameters include the optimal normalized coupling parameters and the optimal normalized saturable absorber parameters that maximize the output energy or maximize the peak power, and the corresponding normalized energy, normalized peak power, and normalized pulse width. Using the expressions and design curves, one can predict the pulse characteristics and perform the design of an optimally coupled GaAs saturable absorber Q-switched laser.     

高分子基础实验的优化与改革

为适应高分子材料与工程专业实验分层次教学改革的要求,结合我院高分子材料与工程专业的具体实际,在教学内容设计中融入科学、节约、环保的理念,对高分子基础实验体系、内容、组织与运行、教学方法与手段进行了整体优化和改革。使实验成本得到降低,污染物明显减少,实验教学效果得到显著提高,实现了高分子专业基础实验教学效益的最大化。