石煤渣保温材料的配方研究

以石煤渣为主要原料研制应用于工业窑炉的保温材料，具有较高的耐压强度和使用温度，导热率低。本文通过分析各原料的主要作用，研究了不同原料掺量对材料性能的影响，从而得到了石煤渣保温材料合理的配方范围为：石煤渣４０％～６０％、可燃造孔物３０％～４０％、粘结剂１２％～２０％、外加剂０．１０％～０．２０％。     

基于VIKOR法的潍坊市水资源承载力综合评价

水资源承载力综合评价通常涉及到社会、经济、资源和环境等多种因素的影响.多准则妥协解排序法（VIKOR）可协调处理多种因素间的相互关系,是评价城市水资源承载力的有效手段之一.本文利用VIKOR法对潍坊市水资源承载力进行综合评价,通过构建水资源承载力综合评价指标体系,利用CRITIC法计算权重,标准化数据并进行分析计算和排序,以利益比率Q_i作为综合评价值,Q_i值越小,表明水资源承载力越高.结果发现,在2008-2017年,潍坊市水资源承载力综合评价值呈下降趋势,从2008年的0.7378下降至2017年的0.0000,表明潍坊市水资源承载力稳步提高.通过分析潍坊市水资源承载力各子系统的变化趋势发现,潍坊市水资源承载能力依然有较大的提升空间.通过对2017年潍坊市各市、区、县水资源承载力进行对比可知,诸城市、青州市、安丘市和临朐县综合评价值较低,分别为0、0.1645、0.2267和0.2503,说明水资源承载力较高;潍城区、坊子区、寒亭区和奎文区综合评价值较高,分别为0.3475、0.4739、0.5938和0.9131,说明水资源承载力较低.表明潍坊市部分地区产业结构和布局与水资源条件不相匹配,水资源开发利用水平超出当地水资源承载力.     

Association between pyrethroid exposure and risk of depressive symptoms in the general US adults

This study aimed to investigate the association between pyrethroid exposure and the risk of depressive symptoms in adults in the USA. Data of participants aged ≥20 years (n = 6455) from the National Health and Nutrition Examination Survey (NHANES, 2007–2014) were included. 3-Phenoxybenzoic acid (3-PBA), an adequately detected pyrethroid metabolite, was used as a biomarker to assess pyrethroid exposure. Depressive symptoms were defined as the Patient’s Health Questionnaire (PHQ-9) total score ≥10 or use of antidepressant. Multivariable logistic regression analyses were performed to examine the association between urinary 3-PBA levels and the risk of depressive symptoms. In this study, 1150 participants (weighted frequency, 18.45%) developed depressive symptoms. Participants in the highest tertile have a higher risk of depressive symptoms than those in the lowest tertile of urinary 3-PBA and weighted OR of 1.28 (95% CI, 1.00–1.63, P=0.019). There was a nonlinear association between urinary 3-PBA and depressive symptoms (P for nonlinearity = 0.034). Mediation analysis showed the mediating effect of trouble sleeping on the association of urinary 3-PBA with depressive symptoms was 28.8% (P = 0.006). Our findings indicate that pyrethroid exposure is associated with the increased risk of depressive symptoms, and trouble sleeping may mediated this association. Further studies should be conducted to validate our findings and elucidate their underlying mechanisms.

     

固定式钢制内压容器的耐压试验压力系数

考虑设计变量的不确定性,应用随机-模糊概率模型,定量分析固定式钢制内压容器初始静强度在耐压试验时的可靠度,研究耐压试验压力系数与超压限制系数、可靠度系数和安全系数之间的关系,解决了把可靠性方法应用于压力容器工程设计的理论基础问题.     

Three-dimensional numerical simulation of water quality and sediment-associated processes with application to a Mississippi Delta lake

A three-dimensional water quality model was developed for simulating temporal and spatial variations of phytoplankton, nutrients, and dissolved oxygen in freshwater bodies. Effects of suspended and bed sediment on the water quality processes were simulated. A formula was generated from field measurements to calculate the light attenuation coefficient by considering the effects of suspended sediment and chlorophyll. The processes of adsorption–desorption of nutrients by sediment were described using the Langmuir Equation. The release rates of nutrients from the bed were calculated based on the concentration gradient across the water–sediment interface and other variables including pH, temperature and dissolved oxygen concentration.The model was calibrated and validated by applying it to simulate the concentrations of chlorophyll and nutrients in a natural oxbow lake in Mississippi Delta. The simulated time series of phytoplankton (as chlorophyll) and nutrient concentrations were generally in agreement with field observations. Sensitivity analyses were conducted to demonstrate the impacts of varying suspended sediment concentration on lake chlorophyll levels.     

影响硝化细菌养殖水污染处理的因素分析研究

为了进一步探讨优化养殖水污染的治理技术,文中介绍了养殖水污染的来源及其成分,提出了相关硝化细菌的基本内容,阐述分析了硝化细菌的保存、分离和污水处理效率等一些相关的影响因素,同时提出可以影响硝化细菌在养殖水污染处理中的因素,这些因素主要有硝化细菌的分离纯化、硝化细菌如何进行保存、硝化细菌如何进行鉴定和硝化细菌如何进行养殖污水处理效率的影响因素,将对进一步提高养殖污水处理效率,促进养殖水污染治理提供一定的帮助.     

Experimental study of NO2 reduction in N2/Ar and O2/Ar mixtures by pulsed corona discharge

Non-thermal plasma technology has been regarded as a promising alternative technology for NOx removal. The understanding of NO2 reduction characteristics is extremely important since NO2 reduction could lower the total NO oxidation rate in the plasma atmosphere. In this study, NO2 reduction was experimentally investigated using a non-thermal plasma reactor driven by a pulsed power supply for different simulated gas compositions and operating parameters. The NO2 reduction was promoted by increasing the specific energy density （SED）, and the highest conversion rates were 33.7%, 42.1% and 25.7% for Ar, N2/Ar and O2/Ar, respectively. For a given SED, the NO2 conversion rate had the order N2/Ar 〉 Ar 〉 02/Ar. The highest energy yield of 3.31 g/kWh was obtained in N2/Ar plasma and decreased with increasing SED; the same trends were also found in the other two gas compositions. The conversion rate decreased with increasing initial NO2 concentration. Furthermore, the presence of N2 or O2 led to different reaction pathways for NO2 conversion due to the formation of different dominating reactive radicals.     

我国非煤矿山安全生产的对策和建议

分析了我国非煤矿山行业面临的挑战，提出了新时期加强非煤矿山安全生产的总体思路和对策措施，强调依法综合管理，并与国际接轨。     

酒精废水消化液生物硝化和脱氮试验

酒精糟液厌氧消化液CODCr浓度为3500～4300mgL,BOD5浓度为1500～2100mgL,TN浓度为400～700mgL,NH3N浓度为300～600mgL。采用SBR反应器对该消化液进行生物脱氮试验,对反应器的有机负荷、氨氮负荷、脱氮效果、脱氮过程中氮形态的变化以及碳源提供等进行了研究分析。试验结果表明,当消化液碳源充足,SBR充水比λ=0.35,缺氧时间3h以及BOD5污泥负荷0.26～0.32kgkg·d条件下,SBR处理出水CODCr598～632mgL,BOD560～100mgL,氨氮6～9mgL,总氮200～216mgL,总氮去除率为60%左右。该处理系统中缺氧段反应时间仅为3h,却承担70%～75%的CODCr总去除负荷,显著提高了该系统的有机负荷和氨氮负荷。在消化液碳源不足的条件下,可投加乙酸钠作为生物脱氮的外碳源,投加量宜为500mgL。     

Machine learning-based models for predicting gas breakthrough pressure of porous media with low/ultra-low permeability

Environmental Science and Pollution Research - Gas breakthrough pressure is a significant parameter for the gas exploration and safety evaluation of engineering barrier systems in the carbon...