Descending Dimension Algorithm of Nolinear Programming Problem with Linear Inequality Constraints

The general nonlinear programming with linear constraints was investigated. In the algorithm, the method of contributing set was used. Comparing with the general contributing set method, the descending dimension method was used to solve the sub-problem with equality constraints in iterative procedure and the problem with inequality constraints. The algorithm is effective by the numerical test. Finally, it was proved that the iteration points are descending, when the objective functions are convex.     

Application of ANSYS to Finite Element Analysis for Nonlinear Masonry Structures

ANSYS has become an effective tool for finite element analysis of masonry structure, but there is few common conclusions for reference. According to the characteristics of ANSYS and the essence of the analysis, some key problems in finite element analysis of masonry structure with ANSYS, such as structural modelling, material constitution, the damage criterion, iterative algorithm, convergence criterion, simulation of prestressing force and so on, are discussed in this paper. Based on the test results of typical masonry structures, the applicability of ANSYS to masonry structural analysis is studied and some suggestions for the application of ANSYS are presented.     

跌落冲击下果实动态本构模型的构建与表征

基于果实非损伤条件下的跌落冲击动力学特征，提出表征其非线性黏弹性的本构模型与模型参数识别方法。该模型包括一个非线性弹簧元件、一个线性增强黏性元件。以苹果为研究对象，进行多个高度下的跌落冲击试验，获得其发生损伤的临界跌落高度；基于临界跌落高度下的冲击试验结果，建立其跌落冲击方程，进行跌落冲击响应的数值分析与模型参数识别。结果表明，理论结果与试验值很吻合，采用本模型结合试验结果能较准确地确定类似特性果实的动态流变特征参数。研究结果为果实动态流变特性分析以及模型表征提供了一种新方法，也为进一步表征果实的黏弹塑性损伤特征提供基础。     

Laccase and phosphatase activities of the dominant ectomycorrhizal types in a lowland oak forest

The year-round dynamics of laccase and acid phosphatase activities of ectomycorrhizas (EM) were monitored in an oak forest, with a microplate photometric method using individual EM root tips. Among the most frequent and abundant EM morphotypes, those of Lactarius quietus and Cortinarius anomalus showed a peak of laccase activity in spring, while those of Xerocomus chrysenteron displayed highest laccase activities in summer and autumn. In comparison, less seasonal differences were observed in EM acid phosphatase activity. This suggests that the different EM types within the EM community perform complementary functions depending on season.     

分析非线性随机结构动态响应的等效随机系统法

在确定性非线性系统等效线性化方法的基础上，提出了分析含有随机参数的非线性结构动态响应的等效随机系统法。考虑了最一般的多自由度系统，以刚度随机为例推导了等效随机系统法的公式，并给出等效随机系统法的算法。以非线性单自由度系统为算例进行计算，结果表明，等效随机系统法得到的解与Monte—Carlo模拟解几乎完全吻合。本方法精度较高，且与Monte—Carlo法相比计算时间大大缩短。     

异龄林生长的动态分析——兼小兴安岭和牡丹江林区冷杉异龄林的生长分析

异龄林既是一个自然生态系统,又是一个复杂的森林经营系统。一个经营工作者要对异龄林进行高效率的经营,就必须掌握现实林的动态变化规律,以便有目的地制定经营措施。异龄林系统从经营角度出发,可以划分成如下三个组成单元:进界生长量、向上生长量和枯损量。上述三个单元的相互作用构成了异龄林系统的动态变化规律。本文的主要目的就是通过对上述三个生长单元的动态进行模拟,寻找出异龄林的动态变化规律,所用方法是对每个生长单元用多个数学模型进行拟合,再通过统计量分析和实际验证从中选出最理想的模型,并据此对现实异龄林的动态进行预测。证明了以曲线形式反映异龄林的动态变化远优于线性形式。所用材料取自黑龙江省小兴安岭和牡丹江林区的冷杉(Abies nephrolepis)为主的异龄针阔混交林。     

输油管道运行优化目标函数的讨论

目标函数的凸性或单峰性是应用非线性规划方法获得问题全局最优解的必要条件。应用数值方法获得多条输油管道算例的运行优化目标函数曲线，并研究其是否满足上述条件。结果显示，总体搜索范围内目标函数呈多峰性及局部锯齿形，表明存在多个局部最优解。据此可推断，输油管道运行优化目标函数在总体搜索范围内一般不满足非线性规划方法获全局最优解的必要条件，按总体范围搜索极有可能仅获得局部最优解。对已提出的多种处理方法进行综合分析，其中任何一种处理方法的实质都是寻找总体搜索范围内全局最优解所处且满足上述条件的较小寻优区间，以便获得真正的最佳运行方案。     

钢管井架稳定性能与承载力的有限元分析

对钢管井架的稳定性能和承载力进行有限元分析。建立了以非线性梁单元为基础的钢管井架有限元计算模型,采用有限元分析软件对其稳定性能进行计算,分析几种主要工程加强措施对井架整体稳定性的作用效果。计算结果表明:井架整体稳定系数约为单杆稳定系数的65%;井架高度、立杆根数(间距)和拉墙杆间距对井架极限承载力的影响很大,工程中可通过增加拉墙杆数量,减小横杆间距等措施提高井架的稳定性和承载力,进而增加井架的工作高度。     

焊接孔长度对钢框架梁-柱刚性节点性能的影响

对焊接孔长度扩大的钢框架梁－柱刚性节点进行了空间非线性有限分析。分析结果表明，焊接孔长工的扩大显著地降低了梁－柱连接面处的对接焊缝和焊接孔切角端开裂以及翼缘脆性破坏的可能性，但过长的焊接孔也会导致梁侧向稳定的丧失。