浇注型耐热聚氨酯树脂材料的合成及性能

以二异氰酸酯(4,4’-二苯甲烷二异氰酸酯MDI;4,4’-二环己基甲烷二异氰酸酯Hl2MDI),聚醚多元醇(PPG),小分子交联扩链剂,催化剂及助剂合成了一系列耐热聚氨酯树脂材料。用FT-IR表征了结构,用X射线衍射分析了微观结构,用DSC,TGA对其热稳定性进行了分析测试,对力学性能也进行了测试。结果表明,合成的聚氨酯材料具有高耐热性和卓越的力学性能。     

一种高精度圆柱形人工边界条件:水-柱体相互作用问题

针对水-柱体动力相互作用问题,提出一种用于模拟无限域水体的圆柱形高精度时域人工边界条件。首先,基于三维可压缩水体的波动方程和边界条件,采用分离变量法建立了时空全局的精确人工边界条件;然后,将其动力刚度表示为外域模型和波导模型人工边界条件动力刚度的嵌套形式;之后,应用时间局部化方法得到时间局部的高精度人工边界条件;最后,离散高精度人工边界条件,并将其与近场有限元方程耦合,形成一种能够采用显式时间积分方法求解的时间二阶常微分方程组。数值算例表明:提出的三维圆柱形高精度人工边界条件精确、高效、稳定。     

Environmental Stress and Plants

Land plants are constantly subjected to multiple unfavorable or even adverse environmental conditions. Among them, abiotic stresses (such as salt, drought, heat, cold, heavy metals, ozone, UV radiation, and nutrient deficiencies) have detrimental effects on plant growth and productivity and are increasingly important considering the direct or indirect effects of climate change. Plants respond in many ways to abiotic stresses, from gene expression to physiology, from plant architecture to primary, and secondary metabolism. These complex changes allow plants to tolerate and/or adapt to adverse conditions. The complexity of plant response can be further influenced by the duration and intensity of stress, the plant genotype, the combination of different stresses, the exposed tissue and cell type, and the developmental stage at which plants perceive the stress. It is therefore important to understand more about how plants perceive stress conditions and how they respond and adapt (both in natural and anthropogenic environments). These concepts were the basis of the Special Issue that International Journal of Molecular Sciences expressly addressed to the relationship between environmental stresses and plants and that resulted in the publication of 5 reviews and 38 original research articles. The large participation of several authors and the good number of contributions testifies to the considerable interest that the topic currently receives in the plant science community, especially in the light of the foreseeable climate changes. Here, we briefly summarize the contributions included in the Special Issue, both original articles categorized by stress type and reviews that discuss more comprehensive responses to various stresses.     

天然气超声流量计健康状态评价方法初探

目的天然气计量用超声流量计性能诊断主要采用设定参数阈值的诊断方法,为降低误报、漏报等情况,建立了基于生成对抗神经网络(generated adjoint neural network,GAN)和高维非线性无监督学习的超声流量计健康状态系统诊断方法。 方法采用GAN对原始数据进行学习、生成和扩充,保障超声流量计健康状态诊断建模的数据基础,提取超声流量计在运行过程中的健康状态参数并对其进行时序分析,采用高维非线性无监督聚类学习方法,结合超声流量计失效模式分析,对超声流量计设备进行在线的健康状态诊断。 结果结合超声流量计工作原理和现场实际采集数据,对生成的故障数据集进行了验证。 结论能够准确识别超声流量计当前状态,显著解决传统阈值法误报率、漏报率高的问题,为超声流量计健康诊断的统一管理与开发给予支撑。      

基于领域知识的多智能体分层协作规划方法

针对复杂动态RoboCup仿真环境下的多智能体协作问题,提出一种使用领域知识的多智能体分层协作规划方法。在根据系统提供的环境状态信息建立智能体初始行为规划的基础上,通过逐步填入智能体的状态和行为特征属性知识,分析行动实现的效果,对初始规划行动进行调整,为智能体制定协调一致的行为规划序列,并获得相应的协作策略信息,使其在实际对抗比赛中能针对当前环境快速做出决策,实现通信受限的情况下多智能体的协作。     

基于K-means聚类和LVQ神经网络的OLED缺陷像素识别

提出改进的K-means聚类分割和LVQ神经网络分类的方法，用于有机发光二极管显示面板喷墨打印制程中缺陷像素的识别。首先采用改进的K-means聚类算法对预处理后的打印像素进行分割，然后采用连通域水平矩形确定每一个打印像素的坐标及几何特征，再通过灰度共生矩阵提取其纹理特征，最后通过LVQ神经网络对所述特征进行分类，完成缺陷像素的标记及分类统计。结果表明，本文算法的识别率明显优于其他常用分类识别算法，平均缺陷检测率为100%，分类准确率达到98.9%，单像素检测时间为8.3 ms。     

基于深度学习的眼底血管图像分割研究进展

眼底血管图像分割对青光眼、糖尿病视网膜病变等多种眼部疾病有较好的辅助诊断作用, 目前深度学习因其强大的抽象特征发现能力, 有望满足人们从眼底血管图像中提取特征信息进行图像自动分割的需求, 成为眼底血管图像分割领域的研究热点. 为更好把握该领域的研究进展, 本文对相关数据集和评价指标整理归纳, 对深度学习在眼底血管图像分割中的应用进行详细阐述, 重点梳理各类分割方法的基本思想、网络结构及改进之处, 分析现有眼底血管图像分割方法存在的局限性及面临的挑战, 并对该领域未来的研究方向做出展望.     

Photorhabdus luminescens TccC3 Toxin Targets the Dynamic Population of F-Actin and Impairs Cell Cortex Integrity

Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by entomopathogenic bacteria of Photorhabdus spp. Unlike other actin-targeting toxins, TccC3 uniquely ADP-ribosylates actin at Thr-148, resulting in the formation of actin aggregates and inhibition of phagocytosis. It has been shown that the fully modified F-actin is resistant to depolymerization by cofilin and gelsolin, but their effects on partially modified actin were not explored. We found that only F-actin unprotected by tropomyosin is the physiological TccC3 substrate. Yet, ADP-ribosylated G-actin can be produced upon cofilin-accelerated F-actin depolymerization, which was only mildly inhibited in partially modified actin. The affinity of TccC3-ADP-ribosylated G-actin for profilin and thymosin-β4 was weakened moderately but sufficiently to potentiate spontaneous polymerization in their presence. Interestingly, the Arp2/3-mediated nucleation was also potentiated by T148-ADP-ribosylation. Notably, even partially modified actin showed reduced bundling by plastins and α-actinin. In agreement with the role of these and other tandem calponin-homology domain actin organizers in the assembly of the cortical actin network, TccC3 induced intense membrane blebbing in cultured cells. Overall, our data suggest that TccC3 imposes a complex action on the cytoskeleton by affecting F-actin nucleation, recycling, and interaction with actin-binding proteins involved in the integration of actin filaments with each other and cellular elements.     

The Role of the Choroid in Stargardt Disease

Stargardt disease is the commonest juvenile macular dystrophy. It is caused by genetic mutations in the ABCA4 gene. Diagnosis is not always straightforward, and various phenocopies exist. Late-onset disease can be misdiagnosed with age-related macular disease. A correct diagnosis is particularly critical because of emergent gene therapies. Stargardt disease is known to affect retinal pigment epithelium and photoreceptors. Many studies have also highlighted the importance of the choroid in the diagnosis, pathophysiology, and progression of the disease. The choroid is in an integral relationship with the retinal pigment epithelium and photoreceptors, and its possible involvement during the disease should be considered. The purpose of this review is to analyze the current diagnostic tools for choroidal evaluation and the extrapolation of useful data for ophthalmologists and researchers studying the disease.     

集成资源预留与QoS监控框架的元调度体系结构

缺乏服务质量保证已成为制约网格应用的瓶颈,针对该问题提出一个能够在网格中基于SLA协商资源预留并监控资源的QoS的服务框架。首先定义资源预留的XML Schema,使得资源请求者和提供者基于WS-Agreement能够协商包含关于资源预留的协定;然后遵循WSRF及WS-*规范设计和开发出一组Web服务用于构建基于WS-Agreement的资源预留与QoS监控框架（RMF）,并集成到GridWay元调度体系结构中使其能够支持基于QoS协商的资源管理;最后通过模拟实验,客观评估了RMF的性能。