军用工程机械轻小型化的若干问题

本文首先指出“军用工程机械轻小型化”的新定义,然后论述实现军用工程机械轻小型的必要性及实现此目标需遵循的原则及技术途径。     

模糊网络计划中模糊工期成本优化方法的研究

针对模糊网络计划的发展,提出了在模糊网络图中模糊工期成本优化的方法,指出应利用遗传算法进行优化,以解决工程中不确定因素的问题,且优化结果更精确。     

简支双轴对称焊接工字型钢梁的设计

从梁的经济高度hec入手,利用梁的翼缘主要作用是平衡弯矩M、腹板的主要作用是承受剪力V的特点,而一般情况下梁的剪力V较小,尽量减薄腹板,将材料尽量用在翼缘上,求出梁的最佳截面.     

Design of composite hybrid plate girder bridges based on reliability and optimization

A practical and efficient reliability-based optimization approach to the design of both unstiffened and stiffened composite hybrid plate girders for highway bridges is presented. The steel weight of the built up plate girder is adopted as the objective to be minimized and all constraints specified in the AASHTO bridge code are considered in the optimization process. The solution is obtained by coupling an optimization program with a reliability analysis program. Numerical examples illustrate the application of the approach to reliability-based optimum design of unstiffened and stiffened composite plate girders. Sensitivity analyses are also performed for finding the rates of change of the optimum solution with respect to changes in problem preassigned parameters.     

高强轻集料混凝土桥面施工泵送技术

轻集料混凝土（LWAC）由轻质多孔集料和水泥石胶结而成。在施工过程中，LWAC由于集料多孔的性质，会从水泥浆中吸收水分，造成混凝土坍落的降低，影响混凝土的泵送性能；另外，LWAC的收缩变形比普通混凝土大，更易使混凝土形成裂缝。通过对LWAC高性能化等技术手段，配制出干表观密度小于1950kg/m^3，易于泵送和体积稳定性好的混凝土。使纤维增强泵送高强（CL40）LWAC技术第一次成功地在我国桥梁工程应用。     

自适应非局部3维全变分彩色图像去噪

目的 许多彩色图像去噪算法未充分利用图像局部和非局部的相似性信息,并且忽略了真实噪声在彩色图像不同区域内分布的差异,对不同图像块和不同颜色通道都进行同等处理,导致去噪图像中同时出现过平滑和欠平滑现象。针对这些问题,本文提出一种自适应非局部3维全变分去噪算法。方法 利用一个非局部3维全变分正则项获取彩色图像块内和块间的相似性信息,同时在优化模型的保真项内嵌入一个自适应权重矩阵,该权重矩阵可以根据每次迭代得到的中间去噪结果的剩余噪声来调整算法在每个图像块、每个颜色分量以及每次迭代中的去噪强度。结果 通过不同的高斯噪声添加方式得到两个彩色噪声图像数据集。将本文算法与其他6个基于全变分的算法进行比较,采用峰值信噪比(peak signal-to-noise ratio,PSNR)和结构相似性(structural similarity, SSIM)作为客观评价指标。相比于对比算法,本文算法在两个噪声图像数据集上的平均PSNR和SSIM分别提高了0.161.76 dB和0.12%6.13%,并获得了更好的图像视觉效果。结论 本文去噪算法不仅更好地兼顾了去噪与保边功能,而且提升了稳定性和鲁棒性,显示了在实际图像去噪中的应用潜力。     

地下工程围岩稳定性的模糊综合评判法

围岩稳定性受多种不确定性因素的影响，不仅具有随机性，也具有模糊性。选择影响围岩稳定性的一些主要因素，采用模糊数学综合评判方法，对围岩稳定用模糊语言进行不同程度的评价，得出了合理的结果。     

Pore blockage effect of NOM on atrazine adsorption kinetics of PAC: the roles of PAC pore size distribution and NOM molecular weight

Natural organic matter (NOM) in natural water has been found to have negative effects on the adsorption of various trace organic compounds by activated carbon through two major mechanisms: direct competition for sites and pore blockage. In this study, the pore blockage effect of NOM on atrazine adsorption kinetics was investigated. Two types of powdered activated carbon (PAC) and three natural waters were tested to determine the roles of PAC pore size distribution and NOM molecular weight distribution in the pore blockage mechanism. When PAC was preloaded with natural water, the pore blockage effect of the NOM was found to cause a reduction of up to more than two orders of magnitude in the surface diffusion rate of atrazine compared to simultaneous adsorption of atrazine and NOM with fresh PAC. The surface diffusion coefficient of atrazine for preloaded PAC decreased with a decrease in PAC dose or an increase in NOM surface concentration. Because of the pore blockage effect of NOM, a 30% drop in atrazine removal was observed in a continuous flow PAC/microfiltration (MF) system after 7 days of contact compared to the removal predicted from the batch isotherm test. Large micropores and mesopores were found to play an important role in alleviating the effect of pore blockage. A PAC with a relatively large fraction of large micropore and mesopores was shown to suffer much less from the pore blockage effect compared with a PAC that had a much smaller fraction of large pores. Natural waters with different NOM molecular weight distribution caused different extent of pore blockage. The NOM molecules with molecular weight between 200 and 700 Dalton appeared to be responsible for the pore blockage effect.     

权重系数法全热换热器效率影响因素判定

利用权重系数建立了全热换热器的全热效率、显热效率及潜热效率三者的关系式,根据显热、潜热效率权重系数判定显热效率、潜热效率对全热换热器全热效率的影响程度。夏季工况下,我国大部分地区空调系统中全热换热器的全热效率主要受潜热效率影响。我国西北地区的空调系统不适合使用全热换热器。     

群决策在房屋结构可靠性评估中的应用

阐述了砌体结构房屋可靠性评估中，各影响因素权重的确定是重要而困难的问题。基于层次分析的群决策确定各因素权重分配时，可有效地减少人为因素的影响，从而使权重确定结果更加客观、科学、合理。