DBU-Based Ionic Liquid Grafted SBA-15 Dual-Functional Catalyst for the Cycloaddition Reaction of CO2 and Epoxide

Catalysis Letters - The development of novel catalysts for the synthesis of cyclic carbonates under mild conditions remains a challenge. Herein, we designed the strategy of immobilizing DBU-based...     

Modeling and analysis of friction in end-face/inner-face circular braiding processes

Friction between yarns could greatly influence braiding processes, especially using carbon/glass fibers. However, as the points of friction are various and traveling all the time, it is quite difficult to measure the total value of frictions. To solve this problem, mathematical models have been developed to predict the friction in two braiding processes of triaxial circular braiding processes, the widely used end-face braiding process and the inner-face braiding process. To analyze the influence of the two braiding processes to the interacted friction between yarns, some definitions and initial conditions were introduced. Based on these conditions, the yarn net, which is formed during the braiding process, was divided into numerous segments. With the geometrical and force equilibrium relationships, each yarn nodes and segments were analyzed. Based on these equations and boundary conditions, the models of two braiding processes were established and solved by Matlab. A practical engineering implementation was shown to verify the validation of the model. The results shows that the inner-face braiding process of braiding process does have a better performance in eliminating the friction than the widely used end-face braiding process.     

海藻酸钙固定化零价铁抗团聚及堵塞的作用机制

以海藻酸钠（SA）、氯化钙、微米零价铁（MZVI）为原料，制备了海藻酸钙（CA）固定化MZVI填料（CAZ），通过静态烧杯实验和动态PRB模型实验，探讨了CA运用对Cr(Ⅵ)的去除性能的影响，并通过电镜扫描分析了CA避免团聚、堵塞机制。实验结果表明，CA凝胶颗粒的运用能显著提升MZVI的除Cr(Ⅵ)性能，CAZ相比MZVI对Cr(Ⅵ)的去除率和反应速率分别提升7.1倍、23.0倍；MZVI利用率的提高是CAZ反应器处理Cr(Ⅵ)水量显著大于MZVI反应器的主要原因，MZVI反应速率的提高是CAZ反应器出水Cr(Ⅵ)浓度显著低于MZVI反应器的主要原因。电镜扫描结果表明，SA与氯化钙交联形成的CA具有丰富的骨架孔道结构，具有骨架支撑作用，能有效克服MZVI颗粒因重力作用导致团聚、降低比表面积的缺陷。CA表层固定的MZVI颗粒与Cr(Ⅵ)反应生成的(Fe_xCr_1-x)(OH)₃ 络合沉淀会冲破CA表层外壳，释放到零价铁-渗透反应墙（Fe⁰-PRB）系统中，导致PRB反应初期出现堵塞现象；大部分MZVI颗粒被固定在CA内部，CA内部有较多孔隙结构，这些孔隙结构会控制(Fe_xCr_1-x)(OH)₃ 络合沉淀释放，从而缓解了Fe⁰-PRB后期长期运行持续堵塞的问题。     

A comprehensive review of computer-aided whole-slide image analysis: from datasets to feature extraction,segmentation, classification and detection approaches

With the development of Computer-aided Diagnosis (CAD) and image scanning techniques, Whole-slide Image (WSI) scanners are widely used in the field of pathological diagnosis. Therefore, WSI analysis has become the key to modern digital histopathology. Since 2004, WSI has been used widely in CAD. Since machine vision methods are usually based on semi-automatic or fully automatic computer algorithms, they are highly efficient and labor-saving. The combination of WSI and CAD technologies for segmentation, classification, and detection helps histopathologists to obtain more stable and quantitative results with minimum labor costs and improved diagnosis objectivity. This paper reviews the methods of WSI analysis based on machine learning. Firstly, the development status of WSI and CAD methods are introduced. Secondly, we discuss publicly available WSI datasets and evaluation metrics for segmentation, classification, and detection tasks. Then, the latest development of machine learning techniques in WSI segmentation, classification, and detection are reviewed. Finally, the existing methods are studied, and the application prospects of the methods in this field are forecasted.

     

无刷直流电机在转子偏心故障时的容错控制研究

在一些工业场合,无刷直流电机需要在转子偏心故障的情形下保持运行状态,而传统的控制策略无法有效地实现容错运行。针对这个问题,提出了一种无刷直流电机在转子偏心时的故障容错控制策略。分析了在传统无刷直流电机控制方法中,每相定子电流参考在波形上是一致的,仅存在一定的相位延迟,而没有考虑电机偏心后导致的反电动势和相电感变化,因此电机偏心将导致未知的转矩脉动。新型控制策略在传统控制策略的基础上采用了在线估计方法,获取了相电感和反电动势的值,从而控制器设置定子电流参考时包含了对偏心故障的考虑和相关运算,从而使电机能够降低转矩脉动,具备一定的故障容错运行能力。最后通过对比试验的方法对新型控制策略进行了试验验证。     

三氟甲基基团的主侧链位置对聚芳醚酮材料性能影响的研究

通过亲核缩聚法制得三氟甲基基团分别位于主链位置和侧链位置的聚芳醚酮,通过1H-NMR确定了两种聚芳醚酮的结构。分析DSC结果发现,三氟甲基基团位于主链位置的聚芳醚酮的玻璃化转变温度（Tg）为166oC,三氟甲基基团位于侧链位置的聚芳醚酮的玻璃化转变温度（Tg）为139oC,因主链的三氟甲基增加了主链的刚性,使得三氟甲基基团位于主链位置的聚芳醚酮具有更高的玻璃化转变温度。三氟甲基基团相对位置不同的聚芳醚酮材料的5%热失重温度均在490oC以上,都表现出良好的热稳定性。分析水接触角结果发现,三氟甲基基团位于主链位置的聚芳醚酮的水接触角为91o,三氟甲基基团位于侧链位置的聚芳醚酮的水接触角为113o,因三氟甲基基团位于侧链位置的聚芳醚酮的氟原子在经过高温处理后更易向薄膜表面迁移,薄膜表面的表面能降低,表现出更加优异的疏水性能。     

自定义响应方程的测井最优化处理方法

目前在用的测井最优化处理方法中涉及的响应方程均为预先定义的固定形式,由于其类型有限,因而针对复杂储层处理的适应性和计算精度都受到影响。针对这一问题,提出了一种基于表达式解析的体外自定义响应方程测井最优化处理方法。通过解析用户输入方程的组成元素,建立与之对应的计算机自动求导、求值算法;针对非线性目标函数求解,提出惩罚函数结合Levenberg-Marquardt的改进算法。现场应用表明,新方法有助于提升测井数据处理的适用性和解释结果的精度。     

反渗透海水淡化脱硼技术的研究

针对海上平台利用反渗透技术进行海水淡化,根据不同季节的取水温度,通过调节进水pH值、增加反渗透运行级数等方法,对海水淡化系统的脱硼效果进行研究,使产水中硼含量达到国家生活饮用水卫生标准。     

基于环境性能模拟的历史建筑更新设计优化研究

作为当代的国际学术热点,特别 是近年来我国建筑界由增量时代转向存量 时代,旧建筑的更新改造成为我国建筑内涵 式增长的关键。我国历史建筑改扩建中建筑 形式与环境脱节以及环境性能低效的矛盾亟 待解决。本文以哈工大土木楼改扩建设计为 例,针对其进行问卷调查,挖掘新时期建筑 学院人群空间行为规律和需求,进而基于 Rhinoceros与Grasshopper平台,结合拓扑思 想与图解静力学理论,探索空间与结构耦合 逻辑以及建筑体量生成方法,并针对其风热 环境进行Ecotect环境性能模拟及评估优化。 比较优化方案与原方案的模拟结果发现,天 窗开启面积占顶界面面积增至15.3%时,过 渡季节逐月不舒适度比例增长0.4%;遮阳面 积为顶界面面积71.8%时,过渡季节逐月不舒适度比例降低2.46%;而在此基础上,天窗开启面积占比增至28.2%,侧界面上舷窗占 比1.8%时,过渡季节逐月不舒适度比例则降低2.19%。基于此,本文提出改扩建设计设置 遮阳设施,辅以可开启天窗与侧立面上舷窗的优化设计策略,进而凝练出基于性能模拟的 历史建筑更新优化设计方法流程,旨在为历史建筑改扩建提供理论指导。     

苯酚丙酮装置废气焚烧炉的系统设计

从多方面分析苯酚丙酮装置的废气焚烧处理,并对该废气焚烧炉的系统设计提出策略性的方案.