基于连续体结构拓扑优化的树状结构拓扑创构

针对概念设计阶段树状结构拓扑创构问题,提出了连续体结构拓扑优化方法。应用连续体结构拓扑优化法,建立体积约束下结构总应变能极小化（即结构总体刚度极大化）的拓扑优化模型,依据单约束优化问题的鞍点条件建立了优化迭代格式。研究了体积比、屋面结构刚度、屋面结构几何形式、设计空间高度等对树状结构拓扑形态的影响,并给出了具体应用算例。结果表明：随着材料用量的增加,树状结构拓扑随之复杂;随着屋面刚度的增加,树状结构分枝趋向于减少;不同的屋面结构几何形式会导致不同的树状结构拓扑形态;满足一定高度后,树状结构分枝形态不会受高度影响,仅是增加主树杆高度。     

山地丘陵城市汇水区划分方法及内涝模拟分析

构建山地丘陵城市排水管网模型时,山岭大面积的雨水汇水区成为研究者必须考虑的问题。针对山岭汇水特点和非线性水库汇流模型的缺陷,提出基于等流时线的山岭汇水区划分方法,将山岭雨水通过虚拟节点和管段排入管网系统。以Z市某辖区排水管网的InfoWorks ICM模拟过程为例,研究了基于等流时线的汇水区划分方法和常规泰森多边形汇水区划分方法对模拟结果的影响。结果表明,采用基于等流时线的山岭汇水区划分方法时,模拟结果与山岭地区雨水汇流过程更为吻合,对该类区域排水管网的排水能力评估和内涝模拟具有一定的借鉴意义。     

气候变化对珠三角地区典型城区流域排水系统的影响

以珠三角地区广州市典型城区流域东濠涌流域为研究区,采用Delta方法和年最大值法相结合推求未来时期东濠涌流域短历时暴雨强度公式,基于InfoWorks ICM构建一二维耦合的东濠涌流域城市雨洪模型,定量评估气候变化对排水系统的影响。结果表明:在RCP4.5和RCP8.5情景下,未来时期降雨强度峰值以及累积降水量均呈增加的变化趋势,城市排水系统节点溢流量、超载管道比例和淹没深度增大,给排水系统带来更为严重的影响。这一结果表明未来时期珠三角地区可能遭受更为不利的洪涝风险灾害。     

ICM理论对主位推进模式在语篇连贯上的补充

文章回溯了主位推进模式和ICM理论对语篇连贯的研究,并据此提出ICM可以有效弥补主位推进模式的不足,从人的认知心理的角度解决主位推进模式无法解释的现象。对语篇连贯的分析应当兼顾形式与心理,应当从功能与认知两个角度出发。     

A combined methodology for the hydraulic rehabilitation of urban drainage networks

During medium and high intensity storm events, urban drainage networks can rapidly reach their maximum capacity, and subsequently floods can occur. Owing to the non-linearity of the processes involved, it is evident that the return period of a rainfall is different from the return period of the generated overflows. Therefore, the assessment of the maximum overflow volume related to a given return period is a key element in the management of urban drainage networks, since it may cause problems to infrastructure and economic losses. In this paper, a combined methodology for the hydraulic rehabilitation of such networks is proposed, by expressing their hydraulic critical conditions in terms of overflow volumes rather than rainfall volumes and considering both observed rainfall data and synthetic hyetographs derived from statistical analysis. The first application of the proposed methodology to the sewer network of the Mesola Municipality is presented and commented on.     

追究根基的结构拓扑优化方法

结合作者在结构拓扑优化方面的研究工作,围绕了ICM(独立、连续、映射)方法涉及的基本概念上的突破,叙述了将本质上为0-1离散变量的拓扑优化问题转化为连续变量优化问题的具体做法,其中介绍了若干要点:以阶跃函数把离散问题化为连续问题即完成关键的等价性转换是第一步;定义磨光函数逼近阶跃函数的可操作的近似是第二步;引入作为磨光函数反函数的过滤函数实现映射性建模是第三步;采用某些光滑算法求解连续变量模型则是第四步。通过连续体结构的典型数值算例说明了将结构拓扑优化的模型转化为独立层次的拓扑优化过程。该方法对于纯数学的0-1离散变量优化的求解也适用,方法与数值都表明了这一点。     

汇水区节点选取对城市雨洪模拟结果的影响

利用Info Works ICM模型建立深圳市光明新区新城公园雨水管网模型,分别以检查井和雨水口作为模型的节点划分汇水区,分析不同的汇水区划分方式对公园出口流量模拟结果的影响。结果表明:在中小降雨条件下,汇水区节点选取对峰值流量模拟结果的影响不明显;在暴雨或特大暴雨的条件下,汇水区节点选取对峰值流量模拟结果的影响较大;与以检查井为节点的划分方式相比,以雨水口为节点的划分方式产流时间会有一定程度的推迟;在模型建立过程中应综合考虑研究目标、区域尺度和降雨特征等对汇水区进行合理划分。     

GA-based design-point performance adaptation and its comparison with ICM-based approach

Accurate performance simulation and estimation of gas turbine engines is very useful for gas turbine manufacturers and users alike and such a simulation normally starts from its design-point. When some of the engine component parameters for an existing engine are not available, they must be estimated in order that the performance analysis can be started. Therefore, the simulated design-point performance of an engine may be slightly different from its actual performance. In this paper, a Genetic Algorithm (GA) based non-linear gas turbine design-point performance adaptation approach has been presented to best estimate the unknown component parameters and match available design-point engine performance. In the approach, the component parameters may be compressor pressure ratios and efficiencies, turbine entry temperature, turbine efficiencies, engine mass flow rate, cooling flows, by-pass ratio, etc. The engine performance parameters may be thrust and SFC for aero engines, shaft power and thermal efficiency for industrial engines, gas path pressures and temperatures, etc. To select the most appropriate to-be-adapted component parameters, a sensitivity analysis is used to analyze the sensitivity of all potential component parameters against the engine performance parameters. The adaptation approach has been applied to an industrial gas turbine engine to test the effectiveness of the approach. The approach has also been compared with a non-linear Influence Coefficient Matrix (ICM) based adaptation method and the advantages and disadvantages of the two adaptation methods have been compared with each other. The application shows that the sensitivity analysis is very useful in the selection of the to-be-adapted component parameters and the GA-based adaptation approach is able to produce good quality engine models at design-point. Compared with the non-linear ICM-based method, the GA-based performance adaptation method is more robust but slower in computation and relatively less accurate.     

一种图像空间下的ICM聚类方法

针对图像聚类问题,提出了一种基于图像空间关系的聚类方法,采用场模型描述图像之间的空间关系,利用K-近邻思想构建图像邻域系统,聚类过程中无需手动标记特征表示的图像类别信息,只需要给定初始类别数,通过条件迭代算法(ICM)对图像进行聚类。该文通过实验分析了图像样本大小、图像特征维数、图像特征类型、初始类别标签对聚类结果的影响,通过与多种经典聚类算法进行对比,实验结果充分验证了该方法的有效性。     

光度非均匀彩色序列图像超分辨率重建

为了实现外界光照变化或相机积分时间自动调节等情况下拍摄的彩色序列图像的超分辨率重建,文章首先提取图像感兴趣区域的方向梯度直方图作为匹配特征,以相关系数作为相似性测度进行几何配准;其次建立光度测量模型进行光度配准;最后采用最大后验估计算法求出光度改善的高分辨率图像。文章采用平均梯度、信息熵、图像对比度对重建图像质量进行评估。实验表明,重建后高分辨率图像平均梯度及信息熵均有大幅提高,图像更清晰、信息更丰富。算法能有效减小重建图像间的光度差异,提高彩色图像的对比度,对光度变化具有一定的鲁棒性。