一种细胞核内DNA物质含量准确测量及回归校正新方法

在定量细胞学研究中,细胞核内DNA物质含量的准确测量是癌症筛查与病理诊断的必要前题与最重要依据。由于算法、设备、环境等因素的影响,在对细胞核的数字显微图像进行处理与分析、测量DNA物质含量时会产生较大的误差。本文提出了一种基于数学形态学和k近邻回归算法的DNA物质含量校正新方法。该方法首先利用膨涨算法对细胞核分割掩码进行处理,从而对DNA物质含量的测量进行空间校正;然后采用k近邻回归算法,充分利用细胞核的形态、纹理等特征参数所蕴含的信息,从而对DNA物质含量进行光学回归校正。实验表明,该方法能够显著提高DNA物质含量测量的准确性和可信度,对提高病理诊断的特异性与敏感性都有积极的意义。     

时变不确定非线性系统自适应滑模跟踪控制

针对一般的具有时变且界未知的非线性不确定性的单输入多输出非线性系统,提出一种自适应滑模跟踪控制器的框架.在该框架内,系统的时变且界未知的非线性不确定性可以通过函数逼近技术(FAT)表示成为一组正交基函数序列的组合,并通过滑模控制技术和直接Lyapunov方法获得基函数系数的更新律以及对不确定性逼近误差的在线自适应补偿,从而得到自适应的滑模控制律.所提出的基于函数逼近技术的自适应滑模跟踪控制策略在直流电机跟踪控制系统实验装置上进行了实际控制实验,并进行了性能的对比与分析.     

遗传编程在符号回归中的应用

遗传编程是一种新型的搜索优化技术,文章介绍了遗传编程的基本原理,以及遗传编程的算法设计及其实现的几个关键问题,并研究了基于遗传编程方法的符号回归。与传统回归方法相比,该方法得到的拟合函数更精确,具有更广泛的适用性。文中通过对一个函数进行符号回归验证,说明此方法合理可行。     

Matlab遗传算法工具箱在非线性优化中的应用

投影寻踪是一种降维处理技术,通过它可以将多维分析问题通过投影方向转化为一维问题分析。应用该法的关键在于寻求最佳投影方向,这可以转化为一个复杂的非线性优化问题来进行解决。选取某地区大气环境质量评价的投影寻踪评价模型,编制相关的目标函数和约束函数,应用基于MATLAB的遗传算法和直接搜索工具箱进行优化求解。结果表明：该工具箱在求解此类非线性优化问题上的有效性和方便性,从而为各领域应用投影寻踪模型提供了强有力的优化工具。     

Small Changes,Big Impact: Tungsten Bronzes with Extremely Large Second Harmonic Generation Achieved by the Transition Metal Doping on the B-Site

Two novel transition metal-doped tungsten bronze oxides, Pb_2.15Li_0.85Nb_4.85Ti_0.15O₁₅ (PLNT) and Pb_2.15Li_0.55Nb_4.85W_0.15O₁₅ (PLNW), are synthesized by high-temperature solid-state reactions. The Rietveld method using the high-resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn2₁ (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d⁰ transition metal cation (Ti⁴⁺ or W⁶⁺)-doped highly distorted NbO₆ octahedra along with the subsequently generated Pb/LiO₁₂ and PbO₁₅ polyhedra. Interestingly, the d⁰ transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH₂PO₄, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO₆ octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B-site of the tungsten bronze structures should be an innovative strategy to develop novel high-performance nonlinear optical materials.     

A nonlinear geometric approach to power system excitation control and stabilization

In this paper, a unified approach to the design of a nonlinear excitation controller/power system stabilizer for a synchronous generator/infinite bus power system is presented. The approach is based on a form of state feedback linearization, known as input–output feedback linearization, which provides an exact semi-global state transformation that is valid for a large class of operating points of the power system. With this transformation, the terminal voltage becomes a linear function of the control input. The excitation controller/power system stabilizer is then synthesized by using linear controller design techniques. The controller is proven to provide small signal stability and to provide local asymptotic tracking of admissible constant reference signals for a large class of operating points. A procedure is given to tune the controller gains to provide significant damping of the power angle oscillations.     

Adaptive control for a class of nonlinear systems with time-varying delays in state and input

This paper is concerned with the adaptive stabilization problem of uncertain input delayed systems.A solution to this problem is given for a class of uncertain nonlinear systems with time-varying delays in both state and input.An adaptive asymptotically stabilizing controller,which can guarantee the stability of the closed-loop system and the convergence of the original system state,is designed by means of the Lyapunov-Krasovskii functional stability theory combined with linear matrix inequalities (LMIs) an...     

Semi‐global output feedback tracking control for fully actuated ships

An output feedback trajectory tracking controller for a kind of 3 degrees of freedom (DOF) ship motion nonlinear model is designed. The closed‐loop control system is proven to be uniformly semi‐globally exponential stable with a separate stability result for the observer by applying nonlinear cascaded system theory. Simulation results on a model ship, Cybership II, are presented to validate the proposed control scheme. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Optimization of optical lens-controlled scanning electron microscopic resolution using generalized regression neural network and genetic algorithm

A scanning electron microscope (SEM) is a sophisticated equipment employed for fine imaging of a variety of surfaces. In this study, prediction models of SEM were constructed by using a generalized regression neural network (GRNN) and genetic algorithm (GA). The SEM components examined include condenser lens 1 and 2 and objective lens (coarse and fine) referred to as CL1, CL2, OL-Coarse, and OL-Fine. For a systematic modeling of SEM resolution (R), a face-centered Box–Wilson experiment was conducted. Two sets of data were collected with or without the adjustment of magnification. Root-mean-squared prediction error of optimized GRNN models are GA 0.481 and 1.96×10^-12 for non-adjusted and adjusted data, respectively. The optimized models demonstrated a much improved prediction over statistical regression models. The optimized models were used to optimize parameters particularly under best tuned SEM environment. For the variations in CL2 and OL-Coarse, the highest R could be achieved at all conditions except a larger CL2 either at smaller or larger OL-Coarse. For the variations in CL1 and CL2, the highest R was obtained at all conditions but larger CL2 and smaller CL1.     

Some algebraic methods for solving multiobjective polynomial integer programs

Multiobjective discrete programming is a well-known family of optimization problems with a large spectrum of applications. The linear case has been tackled by many authors during the past few years. However, the polynomial case has not been studied in detail due to its theoretical and computational difficulties. This paper presents an algebraic approach for solving these problems. We propose a methodology based on transforming the polynomial optimization problem to the problem of solving one or more systems of polynomial equations and we use certain Gröbner bases to solve these systems. Different transformations give different methodologies that are theoretically stated and compared by some computational tests via the algorithms that they induce.