Grey Clustering Theory to Assess the Effect of Mineral Admixtures on the Cyclic Sulfate Resistance of Concrete

Concrete specimens made with ordinary portland cement or ordinary portland cement incorporating fly ash with the replacement of 10% or 20%, ground blast furnace slag with the replacement of 15% or 30%, or 15% fly ash and 15% ground blast furnace slag were made and exposed to a cyclic sulfate environment. Concrete properties including relative dynamic elastic modulus, chloride ion diffusion coefficient, compressive strength and flexural strength were measured. Effect of mineral admixtures on the cyclic sulfa...     

Earth pressure balance control for EPB shield

This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically to simulate the earth pressure variation during excavating. The thrust system and the screw conveyor system for earth pressure cont...     

阻火器的选用

阻火器的选用是石油化工厂、石油和天然气工厂、有可燃性气体的工厂生产安全保护和工程设计中常遇到并需解决的问题，本文对阻火器产品的选用步骤提出了个人的一些理解意见。     

PF用低收缩添加剂的研究

通过调整物料配比合成了端羟基封端和端羧基封端的聚氨酯 (PU)预聚物 ,并分别与酚醛树脂 (PF)固化 ,制备了两种低收缩体系的复合物 ,利用红外光谱对其结构进行表征。通过测试固化物的体系收缩率表明 :随着聚氨酯预聚物加入量的增加 ,PF/PU共混物的体积收缩率明显变小 ,并能达到负值。端羧基PU的低收缩性能更为显著 ,当其加入量在 5 相似文献   

二苯甲酮-β-环糊精包合物的制备表征

采用研磨法合成了二苯甲酮-β-环糊精包合物,经差示量热扫描分析、热重分析、红外分析、X射线衍射分析、对包合物进行了鉴定,证明二苯甲酮-β-环糊精确实形成了一种新的体系.     

Study of UAV tracking based on CNN in noisy environment

Multimedia Tools and Applications - Recently, there are lots of tracking methods proposed to improve the performance of visual tracking in videos with challenging situations, such as background...     

基于多季相Sentinel-2影像的白洋淀湿地信息提取

白洋淀湿地是华北平原上重要的浅水湖泊湿地,对雄安新区绿色发展具有重要的生态价值。对白洋淀高度异质化的景观格局进行分类,能够为白洋淀湿地资源的遥感监测提供指导意义。针对湿地季节变化的特点,对白洋淀每个季节选取一期具有代表性的Sentinel-2影像,采用分类与回归树（CART）、支持向量机（SVM）、随机森林（RF）3种常用的机器学习分类器对15种季相组合实验方案进行分类,分析不同季相遥感影像及其组合对白洋淀湿地信息提取的优劣。结果表明：相较于使用单一季相影像分类,多季相影像的组合能够显著提高分类精度,春&夏季相组合能够得到最优的分类效果,相对单季影像总体分类精度提高了10.9%~25.5%,Kappa系数提高了0.09~0.29;SVM分类器的分类表现较为稳定,能够得到最高的平均分类精度,CART分类器在处理高维特征的能力不如随机森林和SVM;不同特征类型对湿地信息提取的贡献度从高到底依次是红边光谱特征、传统光谱特征、缨帽变换特征、主成分分析特征、纹理特征。实验成果能为湿地信息的遥感识别提供依据。     

Performance‐based near‐optimal vibration control for nonlinear offshore platforms with delayed input

This paper investigates the vibration control problem for offshore platform, where the nonlinear characteristics, delayed input and external wave force are considered in time domain. By introducing a delay‐free reconstructional vector and applying the maximum principle, the original vibration problem for offshore platform is formulated as a nonlinear two‐point‐boundary‐value (TPBV) problem with delayed items. The major contribution of this paper is that a performance‐based near‐optimal vibration control strategy is proposed by solving this nonlinear TPBV problem, which includes a feedback item with offshore platform system state, a feedforward item with wave force state, and a compensator for nonlinear and delayed items with infinite supersensitive component. In particular, the designed compensator is calculated from two group series of linear differential equations by introducing a parameter for expending the Maclaurin series of nonlinear and delay items. Meanwhile, an iterative algorithm is designed to make the proposed vibration control scheme computable based on the control performance in each iterative procedure. Finally, experimental results show that the displacement, velocity and performance index of an employed offshore platform achieved small values under the proposed control strategy and designed algorithm.     

Sensor Fault Diagnosis and Unknown Disturbances Estimation of High Switching Frequency Single-phase PWM Rectifier

International Journal of Control, Automation and Systems - The fault and disturbances estimation has an important role in the modern traction railway system. This paper proposes a unique method for...