基于社会技术系统的复工企业疫情防控风险路径研究*

为对复工企业疫情防控中的风险致因因素进行分析,探寻复工企业疫情防控的风险路径,基于社会技术系统理论,建立宏观工效学模型,通过查阅并分析国家、地方政府、企业文件以及相关文献,从人员、技术、组织管理、内部环境及外部环境5个子系统出发,识别出16个复工企业疫情失控致因因素;运用社会网络分析（SNA）构建复工企业疫情防控关系网络,对各因素节点中心度进行计算,分析各节点在网络中的位置及影响程度;采用贝叶斯网络（BN）进行参数学习和推理学习,找出复工企业疫情失控的最大致因链。结果表明:复工企业疫情失控关系网络中,存在政府监督管理不力→防疫物资筹备不足→日常监管不到位,政府监督管理不力→ 防疫宣传、培训缺失→员工防疫知识欠缺,政府监督管理不力→防疫宣传、培训缺失→日常监管不到位3条最长风险路径。研究结果可帮助复工企业针对最长风险路径中的因素进行管理,从而有效地为复工企业防疫提供理论支持。     

磁浮列车电磁辐射仿真与验证评估技术研究

磁浮列车正常行进过程中对外部环境的电磁辐射安全性近年来受到各科技强国的广泛重视。本文采用多线传输线MTL方法,对磁浮列车电磁辐射场进行了电磁建模与仿真分析,并基于IEEE-Std-C95.1-2005、IEEEStd-C95.6-2002和ICNIP-2010以及GB8702-2014,标准,采用传感器法和接收天线法,现场测试验证了磁浮列车在不同运行状态下的电磁辐射场,开展电磁环境评估工作。研究表明:50～110 kHz,磁浮列车12 m处的辐射磁场呈周期性结构分布,仿真的最大值为69.4 dBuA/m;1～120 kHz频段内,磁浮列车的辐射磁场测量值小于90 mA/m;在9 kHz～18 GHz频段内,磁浮列车的辐射电场均小于110 dBuV/m(0.316 V/m),磁浮列车对外电磁辐射量值比相关国际标准限值至少低30 dB。本论文的研究工作可为我国新型高速磁浮列车电磁安全性研究奠定基础。     

小飞蓬入侵对伊犁河谷草原土壤养分及活性有机碳组分的影响

因小飞蓬繁殖能力强,传播速度快,其入侵后排挤本土植物以较快的速度形成重度入侵群落,对草原生态系统的种类组成和群落结构产生影响.本文以伊犁河谷托乎拉苏草原内自然分布的猪毛蒿和糙叶矢车菊土著植物群落、混有少量小飞蓬的猪毛蒿和糙叶矢车菊轻度入侵群落、猪毛蒿糙叶矢车菊和小飞蓬中度入侵群落、小飞蓬重度入侵群落的4个群落为研究对象,采用样地实验的方法,研究小飞蓬入侵对土壤氮、磷、钾无机养分和活性有机碳组分变化的影响.研究表明,小飞蓬入侵后提高了土壤有机质含量.轻度入侵群落对土壤无机养分需求较大,明显降低土壤速效氮、速效磷、速效钾、硝态氮、铵态氮含量;随着入侵程度加深,逐渐恢复且均高于土著群落含量,其中速效氮含量增加不明显,重度入侵群落在0—10 cm、10—20 cm土层仍处于降低趋势.小飞蓬的入侵对于土壤活性有机碳组分影响较大.轻度入侵时降低土壤微生物活性、阻碍易氧化有机碳的积累,可溶性有机碳含量上升;小飞蓬重度入侵时对微生物量碳、易氧化有机碳含量的影响降低,并促进土壤微生物活性.     

液液萃取-固相萃取-气质联用测定指甲中的多溴联苯醚与多氯联苯

利用液液萃取(LLE)与固相萃取法(SPE)提取和净化人体指甲中的多溴联苯醚(PBDEs)和多氯联苯(PCBs),经浓硫酸除脂后,利用气相色谱-质谱联用仪(GC-MS)测定PBDEs和PCBs.对提取溶剂比例、净化柱类型(复合硅胶柱与固相萃取柱)、固相萃取条件(洗脱溶剂及体积)以及脂肪的去除方法进行了优化,加标回收率较前人基础上均有明显提高.加标回收试验结果显示,PBDEs和PCBs平均基质加标回收率分别为90%—110%和71%—102%,空白加标回收率分别为70%—110%和60%—100%之间,仪器检出限(IDL)分别为0.034—0.120μg·L~(-1)和0.032—0.392μg·L~(-1).本方法快速、简单、高效,能够满足指甲中PBDEs和PCBs的分析.同时本研究利用该方法对电子垃圾拆解地区居民的指甲样品进行测定,PBDEs和PCBs平均浓度分别为623 ng·g~(-1)和148 ng·g~(-1),BDE(-154、-153、-183、-209)和PCB(-8、-28、-52、-66、-101、-77、-118、-153、-187)在所有样品中均检出,女性指甲中PBDEs与PCBs的浓度普遍高于男性.     

A fractal derivative model to quantify bed-load transport along a heterogeneous sand bed

Environmental Fluid Mechanics - Bed-load transport is a complex process exhibiting anomalous dynamics, which cannot be efficiently described using the traditional advection–diffusion...     

Magnetic nanoparticles incorporation into different substrates for dyes and heavy metals removal—A Review

Environmental Science and Pollution Research - Substantial discharge of hazardous substances, especially dyes and heavy metal ions to the environment, has become a global concern due to...     

How does “the Belt and Road” and the Sino-US trade conflict affect global and Chinese CO2 emissions?

Environmental Science and Pollution Research - In the context of the rapid development of the Belt and Road (B&R) Initiative, the continuous transfer of Sino-US trade to the B&R...     

Effects of reciprocal hybridization on cadmium accumulation in F1 hybrids of two Solanum photeinocarpum ecotypes

In this study, farmland and mining ecotypes of Solanum photeinocarpum (a potential cadmium (Cd) hyperaccumulator plant) were reciprocally hybridized each other, and the Cd accumulation characteristics of the F1 hybrids were studied. In pot experiments, higher biomasses and Cd extraction abilities were found for two S. photeinocarpum F1 hybrids than for the parents, but the Cd contents in various organs were lower in the hybrids than the parents. However, the differences between the Cd contents in the two hybrids were not significant. The antioxidant enzyme (superoxide dismutase and peroxidase) activities were higher for the S. photeinocarpum F1 hybrids than the parents. Less DNA methylation was found in the hybrids than the parents because more demethylation occurred in the hybrids than the parents. The biomass, Cd content, and Cd extraction ability effects in field experiments were similar to the effects in the pot experiments. It was concluded that reciprocally hybridizing different S. photeinocarpum ecotypes improved the ability of S. photeinocarpum to be used to phytoremediate contaminated land.