The UF membrane with molecular weight cutoff （MWCO） ranging from 2 to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight （MW） distribution of wastewater effluent organic matt...The UF membrane with molecular weight cutoff （MWCO） ranging from 2 to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight （MW） distribution of wastewater effluent organic matter （EfOM） in terms of TOC and UV254, as well as the amounts of the hydrophilic/hydrophobic organic fractions in different MW ranges. Then, the nanofiltration （NF） membrane fouling experiments were carded out using the above fractionated water to investigate the effect of MW distribution and hydrophihc/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples. The experimental results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic organics with low MW （less than 2 kDa） was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular, the hydrophilic fraction was found to be the most abundant fraction in the effluents. MW distribution has a significant effect on the membrane fouling. When the MW was less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux decline.展开更多
视觉同时定位与地图构建(Simultaneous localization and mapping,SLAM)过程中,动态物体引入的干扰信息会严重影响定位精度。通过剔除动态对象,修复空洞区域解决动态场景下的SLAM问题。采用Mask-RCNN获取语义信息,结合对极几何方法对动...视觉同时定位与地图构建(Simultaneous localization and mapping,SLAM)过程中,动态物体引入的干扰信息会严重影响定位精度。通过剔除动态对象,修复空洞区域解决动态场景下的SLAM问题。采用Mask-RCNN获取语义信息,结合对极几何方法对动态对象进行剔除。使用关键帧像素加权映射的方式对RGB和深度图空洞区域进行逐像素恢复。依据深度图相邻像素相关性使用区域生长算法完善深度信息。在TUM数据集上的实验结果表明,位姿估计精度较ORB-SLAM2平均提高85.26%,较DynaSLAM提高28.54%,在实际场景中进行测试依旧表现良好。展开更多
回环检测是消除同时定位与地图构建(simultaneous localization and mapping,SLAM)系统中累计误差的关键所在,在光照条件或视角变化较大的情况下,传统的基于外观的回环检测方法往往失效。针对这种情况,在ORBSLAM2的框架基础上提出一种...回环检测是消除同时定位与地图构建(simultaneous localization and mapping,SLAM)系统中累计误差的关键所在,在光照条件或视角变化较大的情况下,传统的基于外观的回环检测方法往往失效。针对这种情况,在ORBSLAM2的框架基础上提出一种物体级的回环检测方法。利用目标检测获得的语义信息和特征点信息构建物体级语义地图。将语义地图抽象成拓扑图并将地标抽象成节点,用颜色直方图描述节点信息,结合节点间的几何关系,基于语义和几何一致性约束,提出一种图匹配方法实现回环检测。当检测到回环时,通过物体对齐的方式进行回环校正。在公开的TUM和USTC数据集上进行实验,结果表明提出的系统精度较ORBSLAM2平均提高了49.58%,并且构建的语义地图显示出良好的定位效果。展开更多
为系统了解施工安全事故致因分析领域的发展现状和前沿动态,以Web of Science核心合集数据库中的246篇文献作为数据源,借助CiteSpace软件进行文献计量和知识图谱网络分析。结果表明:施工安全事故致因分析领域发文量总体呈现不断上升趋势...为系统了解施工安全事故致因分析领域的发展现状和前沿动态,以Web of Science核心合集数据库中的246篇文献作为数据源,借助CiteSpace软件进行文献计量和知识图谱网络分析。结果表明:施工安全事故致因分析领域发文量总体呈现不断上升趋势;Safety Science和Accident Analysis and Prevention期刊上发表的相关文章对开展该领域研究具有较强的参考价值;领域内尚未形成较为紧密的学者合作网络。此外,该领域的研究重点包括事故致因理论和模型、事故致因因素和事故致因分析方法,热点趋势包括事故致因因素系统研究横向广度和个体研究纵向深度的延伸、数据挖掘和自动化技术的应用。最后提出加强跨学科研究以全面理解事故致因机理、工人行为的动态特征追踪、高效利用非结构化文本和处理多模态特征数据等几点未来展望。展开更多
基金supported by the National Natural Science Foundation of China (No. 50578131)the National Basic Research Program (973) of China (No. 2008CB417211)the Fund of Shann'xi Educational Committee (No. 05JK243).
文摘The UF membrane with molecular weight cutoff （MWCO） ranging from 2 to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight （MW） distribution of wastewater effluent organic matter （EfOM） in terms of TOC and UV254, as well as the amounts of the hydrophilic/hydrophobic organic fractions in different MW ranges. Then, the nanofiltration （NF） membrane fouling experiments were carded out using the above fractionated water to investigate the effect of MW distribution and hydrophihc/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples. The experimental results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic organics with low MW （less than 2 kDa） was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular, the hydrophilic fraction was found to be the most abundant fraction in the effluents. MW distribution has a significant effect on the membrane fouling. When the MW was less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux decline.
文摘视觉同时定位与地图构建(Simultaneous localization and mapping,SLAM)过程中,动态物体引入的干扰信息会严重影响定位精度。通过剔除动态对象,修复空洞区域解决动态场景下的SLAM问题。采用Mask-RCNN获取语义信息,结合对极几何方法对动态对象进行剔除。使用关键帧像素加权映射的方式对RGB和深度图空洞区域进行逐像素恢复。依据深度图相邻像素相关性使用区域生长算法完善深度信息。在TUM数据集上的实验结果表明,位姿估计精度较ORB-SLAM2平均提高85.26%,较DynaSLAM提高28.54%,在实际场景中进行测试依旧表现良好。
文摘回环检测是消除同时定位与地图构建(simultaneous localization and mapping,SLAM)系统中累计误差的关键所在,在光照条件或视角变化较大的情况下,传统的基于外观的回环检测方法往往失效。针对这种情况,在ORBSLAM2的框架基础上提出一种物体级的回环检测方法。利用目标检测获得的语义信息和特征点信息构建物体级语义地图。将语义地图抽象成拓扑图并将地标抽象成节点,用颜色直方图描述节点信息,结合节点间的几何关系,基于语义和几何一致性约束,提出一种图匹配方法实现回环检测。当检测到回环时,通过物体对齐的方式进行回环校正。在公开的TUM和USTC数据集上进行实验,结果表明提出的系统精度较ORBSLAM2平均提高了49.58%,并且构建的语义地图显示出良好的定位效果。
文摘目的:对比本体感觉神经肌肉易化技术(proprioceptive neuromuscular facilitation,PNF)、向心-等长-快速离心训练、向心-等长-慢速离心训练对青年柔韧性扁平足患者的干预效果。方法:将40名受试者随机分为PNF组、向心-等长-快速离心组、向心-等长-慢速离心组、对照组,每组各10人。共进行6周运动干预,实验前后测试各组足舟骨下降试验(navicular drop test,NDt)高度差、标准舟骨高度指数(normalized navicular height truncated,NNHt)、踝关节肌肉力量、足底压力分布特征、动态平衡能力。结果:(1)足弓形态:与实验前相比,PNF组优势侧NDt值显著变小(P=0.049),向心-等长-快速离心组非优势侧NDt值显著变小(P=0.034)、NNHt指数显著变大(P=0.026);(2)踝关节力量:与实验前相比,PNF组、向心-等长-快速离心组、向心-等长-慢速离心组跖屈肌力均显著提升(优/非优势侧:P=0.003/P=0.004、P=0.000/P=0.000、P=0.001/P=0.001),PNF组、向心-等长-快速离心组内翻肌力均显著提升(优/非优势侧:P=0.011/P=0.005、P=0.003/P=0.003);(3)足底压力分布特征:与实验前相比,在非优势侧中,向心-等长-快速离心组足底压力中心(center of pressure,COP)连线增量显著降低(P=0.037),PNF组内侧纵弓负荷比例及接触面积显著降低(P=0.012、P=0.027);在优势侧中,向心-等长-慢速离心组内侧纵弓接触面积显著减小(P=0.038),对照组则显著增大(P=0.015);(4)动态平衡:与实验前相比,PNF组、向心-等长-慢速离心组优/非优势侧及向心-等长-快速离心组优势侧Y-Balance测试综合分数显著提高(P=0.006/P=0.023、P=0.001/P=0.035、P=0.011)。结论:6周PNF治疗可改善柔韧性扁平足青年的足弓形态,并提升其动态平衡能力;6周向心-等长-快速离心训练在改善柔韧性扁平足青年足弓形态方面效果最为显著,而向心-等长-慢速离心训练可显著提升柔韧性扁平足青年的动态平衡能力。
文摘为系统了解施工安全事故致因分析领域的发展现状和前沿动态,以Web of Science核心合集数据库中的246篇文献作为数据源,借助CiteSpace软件进行文献计量和知识图谱网络分析。结果表明:施工安全事故致因分析领域发文量总体呈现不断上升趋势;Safety Science和Accident Analysis and Prevention期刊上发表的相关文章对开展该领域研究具有较强的参考价值;领域内尚未形成较为紧密的学者合作网络。此外,该领域的研究重点包括事故致因理论和模型、事故致因因素和事故致因分析方法,热点趋势包括事故致因因素系统研究横向广度和个体研究纵向深度的延伸、数据挖掘和自动化技术的应用。最后提出加强跨学科研究以全面理解事故致因机理、工人行为的动态特征追踪、高效利用非结构化文本和处理多模态特征数据等几点未来展望。
