基于动态阈值的混凝土裂缝高抗噪提取及识别方法

针对表面布有蜂窝麻面等复杂噪声的混凝土裂缝,提出了一种基于动态阈值的混凝土裂缝高抗噪提取方法.首先,通过灰度变换、高斯滤波、信息增强等技术弱化、去除噪声,增强图像中裂缝的亮度,提高裂缝与背景的对比度;然后,采用OTSU阈值分割算法去除伪裂缝,基于裂缝与干扰噪声面积的差异,引入动态阈值,实现各类型裂缝的提取;最后,基于边缘检测和裂缝骨架细化处理,计算裂缝的长度、宽度和面积3项特征参数.基于室内实验和室外实际桥梁拍摄的4组裂缝图像结果表明,4组裂缝的平均宽度分别为2.01、1.07、1.34、0.97 mm,说明该方法适用于不同背景下各类型裂缝的提取,具有较强的鲁棒性.     

Multifunctional artificial nacre via biomimetic matrix-directed mineralization

Natural nacre, one of the most studied biological structural materials with delicate hierarchical structures and extraordinary performance, has inspired the design and fabrication of artificial structural ceramics with high fracture toughness. However, to meet the diverse requirements of different applications, future structural materials must be multifunctional with superior mechanical properties, such as strength, hardness, and toughness. Herein, based on the matrix-directed mineralization method for producing biomimetic structural materials, we introduce nanoparticles with different inherent functions into the platelets of artificial nacre via the co-mineralization of aragonite and the nanoparticles. Besides their enhanced mechanical properties, the obtained artificial nacre materials also exhibit different functions depending on the type of the nanoparticles. To extend the versatility of this strategy, the effects of nanoparticles of different sizes and zeta potentials on mineralization are also analyzed. This universal strategy can be applied to the fabrication of other types of functionalized biomimetic structural ceramics that have potential applications in various fields, such as biomedical science.     

水平循环荷载引起的砂土沉陷-致密作用对刚性桩承载力的影响分析

为研究砂土中刚性桩基础在循环荷载作用下的承载力演化规律,提出了一种循环后单桩承载力的评估方法.首先,基于沉陷坑与致密区域土体的质量守恒原理,量化了由沉陷引起的土体参数变化;然后,根据API规范中的砂土水平土抗力-位移模型计算循环前后的单桩承载力;最后,提出了循环后单桩承载力的评估模型,并对沉陷坑尺寸、土体初始相对密实度和致密区域模式等因素进行对比分析.结果 表明:单桩承载力随沉陷坑的发展不断增大;对于松砂、中密砂和密砂,循环后的单桩承载力可分别提高约3.0、1.5、1.2倍,提高幅值随相对密实度的增大而降低;2种土体变形模式中,单锥模式相比于双锥模式更符合真实的致密区域形态.     

Evolutionary game analysis of low-carbon behavior credit supervision of logistics enterprises

Based on the low-carbon obligation fulfillment of Chinese logistics enterprises, this study constructs a tripartite evolutionary game model to analyze the evolutionary process of the interaction between the local government, logistics enterprises and the public in the process of low-carbon behavior credit supervision. Then using Netlogo software, a parameter simulation experiment is conducted to determine the optimal policy for improving the effect of supervision. The results are as follows: ① The combined influence of the local government and the public can effectively change the strategic choice of enterprises and promote the low-carbon behavior of enterprises. ② In terms of improving the effect of supervision, reducing the cost of government supervision would have a highly significant effect, and reducing the cost of the public would be counterproductive. ③ Increasing the government subsidies to enterprises and the government’s fines to enterprises both have a significant effect, and the effect of improving the former is better. However, increasing the severity of higher-level governments punishing local governments will reduce the stability of the system. ④ Supervision can be more effective by increasing the public’s impact on enterprises’ earnings rather than by increasing government subsidies to the public.     

Facile synthesis of flake-like dihydrate zinc oxalate particles

Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.     

Advancements in theory of GHG observation from space

As a large developing country,China has the highest level of greenhouse gas(GHG)emissions.The Chinese government is seeking sustainable development and trying to reduce GHG emissions.From the scientific perspective,there are     

羟肟酸浮选分离选择性的定量构效关系

采用定量构效关系方法和遗传算法对13种芳烷基羟肟酸类捕收剂的锡石-萤石浮选分离选择性指数进行了定量构效关系研究,旨在预测羟肟酸捕收剂对锡石-萤石浮选分离的选择性能.采用快速分子描述符和量子化学描述符建立了两种选择性指数的二元因子模型,选择性指数1的模型5和选择性指数2的模型6的相关系数R2分别为0.868和0.796,R2cv分别为0.779和0.590.使用留一法对两模型进行内部验证的相关系数R2分别为0.785和0.615,使用测试集对两模型进行外部验证,所得两模型的平均预测绝对误差分别为0.095和1.939.指数1模型具有真实有效性和较好的预测能力,能够有效预测羟肟酸的选择性.     

An improved LP model for energy optimization of the integrated iron and steel plant with a cogeneration system in China

In an integrated iron and steel plant with a cogeneration system, recycled energy is continuously transported into the cogeneration system and the electricity is continuously generated, and both of them could not be stored for a long time. Moreover, the generation and consumption of electricity is irregular, which may bring about more unexpected imbalances. Therefore, it is a crucial issue to schedule the entire energy system by optimizing the operation of energy utilization, which includes the raw energy in the production system, the generation electricity in the cogeneration system and the recycled energy in these two systems. In this paper, an improved Linear Programming model for energy optimization in the integrated iron and steel plant with a cogeneration system is established. The improved model focuses on controlling the whole energy flow and scheduling the whole energy consumption in the entire energy system between the production system and cogeneration system through optimizing all kinds of energy distribution and utilization in an integrated iron and steel plant with a cogeneration system. Case study shows that the improved model offers the optimal operation conditions at the higher energy utilization, lower energy cost and lower pollution emissions.     

纤维金属层板的拉伸性能研究

GLARE是一种先进的混杂层板材料,由高韧度薄铝合金层和高强度玻璃纤维/环氧树脂层交替铺设而成,具有独特的轻质、耐疲劳、耐冲击、高阻燃性和耐腐蚀属性.系统地对GLARE层板进行了静力拉伸测试,展示了铺层结构和铺层类型对其静力学性能的影响,并对混杂模型的适用性进行了验证.结果显示:采用混杂模型法预测GLARE层的轴向弹性模量具有较高的精度,但进行强度预测时对于部分类型的层板需要考虑纤维的桥接作用.