大直径开孔数控火焰切割机的研制

介绍了DKK-1型大直径开孔数控火焰切割机的设计方案及实际使用情况.该设备可完成在圆柱壳体上的大直径相贯圆孔的开孔及切坡口工作,开孔直径范围(Φ1.0～3.0m).所开孔可以是正交孔,也可以是偏心孔,并可切割变角度上下坡口.割炬高度变化范围:1.0m,切割厚度变化范围:30～120mm,切割圆孔精度:±1mm.采用齿圈转桥式旋转机构、悬臂和弧板式枪摆机构相结合的结构设计.采用程序控制、示教和人机共享控制相结合的控制策略.工控机作为数控系统主机,三相混合式步进电机作为控制电机,光电编码器作为测量器件.本文着重对机械结构设计、数控系统软硬件设计进行了讨论,并给出了设计中应注意的一些问题.本设备已成功地应用于舰船建造.     

Robust matrix 𝒟U‐stability analysis

In this paper, the problem of robust matrix root‐clustering is addressed. The studied matrices are subject to both polytopic and unstructured uncertainties. An original point is the large choice of clustering regions enabled by the proposed approach since these regions can be unions of possibly disjoint and non‐symmetric subregions of the complex plane. The precise purpose is, considering a specified polytope, to determine the greatest robustness bound on the unstructured uncertainty such that robust matrix root‐clustering is ensured. To reduce conservatism in the derivation of the bound, the reasoning relies on a framework based upon parameter‐dependent Lyapunov functions. The bound value is computed by solving an ?? ?? ? problem. Copyright © 2003 John Wiley & Sons, Ltd.     

非完整自主车基于圆轨迹的道路避障

本文就四轮非完整自主车提出了一种基于圆轨迹的道路避障策略．先将道路上 的障碍按照障碍距离自主车的远近划分层次，使一个层次的障碍能在自主车视场中全部出现 ．然后给出基于圆轨迹的避障算法，即自主车沿由自主车出发位姿和子目标点确定的圆弧轨 迹走行．在此之前推导四轮非完整车的运动模型为提出避障策略的基础准备．尽量减小自主 车在走行过程中运动状态的改变，基于圆轨迹避障策略能够很好地满足这一要求．最后引入 代价函数，给出对于此方法的评价，体现了本方法的优越性．     

生成圆弧的等距线约束方法及其应用

栅格圆弧的生成算法在计算机图形学和图像处理中有着大量的应用．一条曲线一定位于该线两侧的两条到该线距离足够小的等距线之间，或认为该曲线受其两侧的两条等距线的约束．本文从真实圆弧曲线受其两侧的等距圆的约束出发，提出一种生成栅格圆弧的等距线约束算法，并分析了该算法的精度．其优点是可单方向连续生成圆弧，且生成的两个相邻栅格圆之间不会有空隙或重叠，因此可直接用于圆域有关的图形生成和栅格点扩散搜索．本文最后研究了该方法在栅格圆环、圆盘及球面、球等生成及Euclid距离变换中的应用．     

圆与多边形重叠区域的判定算法

本文提出了一种实用的圆与多边形重叠区域的判定算法，它集判断与确定功能于一体。该算法将多边形的边视为有向线段，通过引入多边形顶点的入边，出边交点的概念，研究了圆与多边形重叠区域的确定问题，并给出了作出其重叠区域的定理。     

An Accelerated Iterative Method for Simultaneously Determining All Roots of Polynomial Equation

In this paper, an accelerated iteration method for simultaneously determining of a polynomial equation's roots is proposed. The new method is an improvement of modified Newton method. At the same time, convergence properties and the order of convergence rate are discussed. At last, some numerical results are reported and listed.     

玉米根系几何造型研究

通过对玉米根系形态建成过程根系的结构、生长及分布特点和规律观测研究,构建了描述玉米根系形态变化的数学模型。结合粒子系统和计算机图形学技术,在计算机上实现了玉米根系生长的三维显示。其结果和实际的玉米根系的生长发育过程基本一致,为农学研究者提供了一个可视化的根系模型。本模型结构简单、可交互、真实感强,可以较好地虚拟玉米根系的生长过程。     

砌体结构房屋底层墙体开洞时洞口最大宽度计算的探讨

本文根据国家现行规范和结构构件承载能力极限状态分析．提出了砌体结构房屋底层墙体开洞宽度的计算方法，供工程技术人员在工程实践中参考。     

流动注射悬浮液脉冲进样--火焰原子吸收光谱法测定中草药生地中的铁和锌

以流动注射悬浮脉冲进样－火焰原子吸收光谱法进行了中草药生地中铁和锌元素的测定，生地被干燥，粉碎，过筛后加入琼脂溶液制成悬浮液，然后用流动注射脉冲送入雾化器。实验考察了仪器工作条件，样品悬浮液制备和方法的准确性，用标准加入法测定，该法简便，快捷，测定结果与灰化法一致。     

Overexpression of an F-box Protein Gene Reduces Abiotic Stress Tolerance and Promotes Root Growth in Rice

As one of the largest gene families, F-box domain proteins have important roles in regulating various developmental processes and stress responses. In this study, we have investigated a rice F-box domain gene, MAIF1. The MAIF1protein is mainly localized in the plasma membrane and nucleus. MAIF1 expression is induced rapidly and strongly by abscisic acid (ABA) and abiotic stresses. MAIM expression is also induced in root tips by sucrose, independent of its hydrolytic hexose products, glucose and fructose, and the plant hormones auxin and cytokinin. Overexpression of MAIF1 reduces rice ABA sensitivity and abiotic stress tolerance and promotes rice root growth. These results suggest that MAIF1 is involved in multiple signaling pathways in regulating root growth. Growth restraint in plants is an acclimatization strategy against abiotic stress. Our results also suggest that MAIF1 plays the negative role in response to abiotic stress possibly by regulating root growth.