Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review

This article reviews past studies of airborne transmission between occupants in indoor environments, focusing on the spread of expiratory droplet nuclei from mouth/nose to mouth/nose for non‐specific diseases. Special attention is paid to summarizing what is known about the influential factors, the inappropriate simplifications of the thermofluid boundary conditions of thermal manikins, the challenges facing the available experimental techniques, and the limitations of available evaluation methods. Secondary issues are highlighted, and some new ways to improve our understanding of airborne transmission indoors are provided. The characteristics of airborne spread of expiratory droplet nuclei between occupants, which are influenced correlatively by both environmental and personal factors, were widely revealed under steady‐state conditions. Owing to the different boundary conditions used, some inconsistent findings on specific influential factors have been published. The available instrumentation was too slow to provide accurate concentration profiles for time‐dependent evaluations of events with obvious time characteristics, while computational fluid dynamics (CFD) studies were mainly performed in the framework of inherently steady Reynolds‐averaged Navier‐Stokes modeling. Future research needs in 3 areas are identified: the importance of the direction of indoor airflow patterns, the dynamics of airborne transmission, and the application of CFD simulations.     

Effects of yoghurt butter oils on rat plasma lipids,haematology and liver histology parameters in a 150‐day study

Although yoghurt butter oil as a fermented dairy product is widely consumed in several countries, its metabolic effects have not been fully elucidated. In this study, male Wistar rats were treated with standard diet, standard diet enriched with 10% or 20% (W/W) of either cow yoghurt butter oil (CYBO), sheep yoghurt butter oil (SYBO) or cottonseed oil (COT) for 20 weeks. Treatment of rats with CYBO or SYBO (at both concentrations) did not significantly influence haematological parameters, plasma lipids and liver histological structure. However, in contrast to popular belief, COT treatment at the higher dose induced leukocytosis, dyslipidaemia and liver steatosis.     

Simulation Study on Hydrogen-Heating-Power Poly-Generation System based on Solar Driven Supercritical Water Biomass Gasification with Compressed Gas Products as an Energy Storage System

Supercritical water gasification driven by solar energy is a promising way for clean utilization of biomass with high moisture content, but direct discharge of liquid residual causes energy waste and decreases energy efficiency. To reduce energy waste, a poly-generation system for hydrogen-rich gas production coupling heat supply and power generation based on supercritical water gasification of biomass driven by concentrated solar energy was established in this paper, which also provided a novel energy storage method to overcome the shortcomings of solar discontinuity. Thermodynamic model of the system was proposed and life cycle assessment(LCA) of the system was conducted. Influence of different parameters(temperature of 600℃ to 800℃, outlet temperature of heat exchanger of 42℃ to 56℃, biomass slurry concentration of 5% to 6.5%) on the gasification performance, energy and exergy efficiency, energy distribution and global warming potential(GWP) was discussed. The results indicated that hydrogen yield increased as gasification temperature increased since free radical reaction was enhanced which gas production reaction was classified into. Molar fraction of hydrogen increased as gasification temperature increased and reached 65.6% at 750℃. Energy and exergy efficiency of the system reached 74.84% and 34.87% at 700℃ and 600℃ respectively and that of gas production was 18.15% at 650℃, which was the highest. Increasing reaction temperature and decreasing biomass slurry concentration were effective ways to decrease GWP. Optimal operating parameter was reaction temperature of 650℃, outlet temperature of heat exchanger of 50℃ and biomass concentration of 5%.     

基于峰谷分时电价的虚拟电厂日前申报及运行优化

鉴于分布式能源的出力性质为间歇性和波动性,影响电网安全高效运行,而虚拟电厂可解决此问题。对虚拟电厂进行申报-调度两阶段建模,以包含分布式电源(光电、风电和燃气轮机)和储能系统(储能电池)两大类分布式能源的虚拟电厂为例,基于光照强度及风速等不确定因素,研究峰谷分时电价下日前市场虚拟电厂的出力申报和运行调度策略并利用风险价值模型进行风险管理。结果表明,申报出力时,当电价激励足够高时储能电池方会参与出力,成功起到削峰填谷的作用;运行调度时,平衡出力偏差方面,储能电池发挥主要作用,且虚拟电厂运行调度策略具有一定的经济效益。     

计及风险规避的电力零售商平衡市场交易模型

由于新能源出力以及终端负荷需求的不确定性,电力零售商在日前市场的竞标电量与实时市场的购买电量之间存在不平衡而产生惩罚成本风险。引入用户侧可控负荷作为平衡资源参与市场交易,提出了一种风险规避程度指标,以此来度量交易前后电量偏差程度,以信息熵度量残差序列离散程度计算风险规避程度指标。以电力零售商运行收益、用户需求响应满意度以及风险规避程度最大为目标建立多目标风险规避模型,采用自适应权重粒子群算法进行模型求解。通过算例表明,所提出的模型从电网-电力零售商-用户多个角度去考虑电力零售商参与平衡市场交易策略,能够有效提高电力零售商的运行效益以及用户满意度,同时可以提高电力市场管理的可靠性与安全性。     

地勘单位转制后税务风险识别与控制

结合“减税降费”的政策背景,以陕西省某转制地勘单位为例,引入风险控制相关理论并应用层次分析法,构建了税务风险评估指标体系,对转制地勘单位面临的税务风险进行了识别、分析、评估。研究结果表明:针对不同的税收类型,应着重关注不同方面的风险,排序前6位的风险依次为企业所得税扣除类风险、增值税决策环节风险、增值税销售环节风险、房产税计税依据风险、企业所得税税收优惠类风险、增值税采购环节风险;并对上述风险的控制机制进行了分析,从企业管控、政策优化两方面分别提出了相关对策和建议。     

基于信息熵—集对分析的煤矿隐患排查治理风险评估模型

以煤矿安全隐患排查治理风险为研究对象，分析隐患排查闭环管理全过程，并基于此建立了隐患排查治理能力纵向评估指标体系，融合熵值法和集对分析理论，建立了煤矿安全隐患排查治理风险纵向评估模型，为企业更好地了解自身隐患排查治理能力及变化发展趋势提供参考，最后进行了实例分析。     

长江武惠堤堤防渗透破坏风险计算模型及应用

针对渗透水压力引起堤防渗透破坏问题,以堤防渗透破坏风险为目标,考虑堤防计算水位条件和土层渗透系数的不确定性,建立了堤防渗透破坏风险计算模型。以长江武惠堤17+750断面为例,对汉口水文站水位监测资料进行分析并拟合水位概率密度函数,对该断面渗流规律进行有限元分析,从而拟合渗透破坏概率密度函数,以此建立该断面堤防渗透破坏风险定量表达式。研究结果表明,武惠堤17+750断面堤防在警戒水位与防洪设计水位下,渗透破坏概率分别为0.442 9、0.764 0,渗透破坏风险分别为0.001 421、0.002 52;堤防渗透破坏风险随着堤外水位的升高而增加,但在防洪设计水位内运行时,堤防渗透破坏风险低,堤防渗流安全可得到有效控制。     

基于灾度辨识的钢闸门巡视检查研究

巡视检查是对钢闸门要点部位开展定期、定点的信息收集,并对警兆信息做出快速辨识和评估的重要内容。应用灾度辨识的警兆信息评估方法,综合钢闸门巡视检查的各类要素信息,明确工程最大隶属的灾度等级(Ⅰ～Ⅴ级),可作为工程日常巡视检查决策的重要软技术手段。