Spatiotemporal Variability of Modeled Watershed Scale Surface‐Depression Storage and Runoff for the Conterminous United States

This study explores the viability of using simulated monthly runoff as a proxy for landscape‐scale surface‐depression storage processes simulated by the United States Geological Survey’s National Hydrologic Model (NHM) infrastructure across the conterminous United States (CONUS). Two different temporal resolution model codes (daily and monthly) were run in the NHM with the same spatial discretization. Simulated values of daily surface‐depression storage (treated as a decimal fraction of maximum volume) as computed by the daily Precipitation‐Runoff Modeling System (NHM‐PRMS) and normalized runoff (0 to 1) as computed by the Monthly Water Balance Model (NHM‐MWBM) were aggregated to monthly and annual values for each hydrologic response unit (HRU) in the CONUS geospatial fabric (HRU; n = 109,951) and analyzed using Spearman’s rank correlation test. Correlations between simulated runoff and surface‐depression storage aggregated to monthly and annual values were compared to identify where which time scale had relatively higher correlation values across the CONUS. Results show Spearman’s rank values >0.75 (highly correlated) for the monthly time scale in 28,279 HRUs (53.35%) compared to the annual time scale in 41,655 HRUs (78.58%). The geographic distribution of HRUs with highly correlated monthly values show areas where surface‐depression storage features are known to be common (e.g., Prairie Pothole Region, Florida).     

Study on the dynamic response of polyurea coated steel tank subjected to blast loadings

Steel tanks are widely used in the storage of various chemical liquids, and the blast resistance of the tanks is very important because of the explosiveness of these liquids. To explore a feasible method to improve the blast resistance of steel tanks, the effect of polyurea coating on the blast resistance of steel storage tank is investigated in this paper. The responses of monolithic steel tanks and polyurea coated tanks under blast loads are studied by field blast experiments using TNT explosive, and the results shows that the polyurea layers are effective in reducing the maximum and residual displacements of the tank. Numerical simulations are performed and validated, and the deformation process and stress and strain distribution of the tanks are analyzed accordingly. The increase on the bending moment of the plastic hinge lines of the tanks and the increase of the area density of the cylindrical shell induced by the polyurea layers are believed to be the two main factors contributing to the displacement reduction effect of polyurea in this paper. The validated numerical model is used to study the influence of polyurea layer's thickness on the deflection of the tank, and a nearly inversely proportional relationship between the thickness and the maximum displacement is found. Three deformation modes of the tanks are identified when subjected to blast load with varying intensity and it is found that the displacement reduction effect of polyurea varies in different deformation modes.     

Photosynthesis and related metabolic mechanism of promoted rice (Oryza sativa L.) growth by TiO2 nanoparticles

• The rice growth was promoted by nano-TiO₂ of 0.1–100 mg/L. • Nano-TiO₂ enhanced the energy storage in photosynthesis. • Nano-TiO₂ reduced energy consumption in carbohydrate metabolism and TCA cycle. Titanium dioxide nanoparticle (nano-TiO₂), as an excellent UV absorbent and photo-catalyst, has been widely applied in modern industry, thus inevitably discharged into environment. We proposed that nano-TiO₂ in soil can promote crop yield through photosynthetic and metabolic disturbance, therefore, we investigated the effects of nano-TiO₂ exposure on related physiologic-biochemical properties of rice (Oryza sativa L.). Results showed that rice biomass was increased >30% at every applied dosage (0.1–100 mg/L) of nano-TiO₂. The actual photosynthetic rate (Y(II)) significantly increased by 10.0% and 17.2% in the treatments of 10 and 100 mg/L respectively, indicating an increased energy production from photosynthesis. Besides, non-photochemical quenching (Y(NPQ)) significantly decreased by 19.8%–26.0% of the control in all treatments respectively, representing a decline in heat dissipation. Detailed metabolism fingerprinting further revealed that a fortified transformation of monosaccharides (D-fructose, D-galactose, and D-talose) to disaccharides (D-cellobiose, and D-lactose) was accompanied with a weakened citric acid cycle, confirming the decrease of energy consumption in metabolism. All these results elucidated that nano-TiO₂ promoted rice growth through the upregulation of energy storage in photosynthesis and the downregulation of energy consumption in metabolism. This study provides a mechanistic understanding of the stress-response hormesis of rice after exposure to nano-TiO₂, and provides worthy information on the potential application and risk of nanomaterials in agricultural production.     

弹用聚酰胺材料老化试验研究

以聚酰胺材料老化试验为例,讨论了储存寿命预测的分析技术、试验设计技术;提出了影响试验准确性的因素和解决问题的方法,因素包括试验样品选择、考核性能选择、试验方法选择、产品环境剖面分析、热老化温度确定等。     

环境对冲压发动机烟火点火器性能影响研究

为促进某型冲压发动机烟火点火器生产工艺的定型,在海南进行了高温、高湿热带海洋气候自然环境对点火器长期贮存性能影响的研究。点火器采取无包装的暴露试验和密封包装贮存试验2种方法,分别在户外暴露场、棚库和库房等3种环境条件下进行试验。通过试验得到环境温度变化对密封包装储存的点火器的绝缘电阻值、电阻性能均无明显影响,点火性能良好,玻璃钢、涂层等贮存性能良好,点火器的环境适应性良好等结论。     

三峡水库典型支流磷素赋存形态特征及其成因

采用2018年三峡水库低水位期(6月)、蓄水期(9月)和高水位期(12月)对库区内的典型一级支流——香溪河与神农溪回水区水质、水动力及环境因子的监测数据,对比分析了三峡水库内的典型支流在水库不同调度期时水体中磷素的存在形态及成因.结果表明,香溪河与神农溪库湾水体总磷(TP)质量浓度变化范围分别为0.049～0.168m...     

峨眉山景区旅游商品的开发与营销模式

通过对旅游商品定义的综述,界定了旅游商品的定义、范围和功能,同时对峨眉山景区旅游商品的开发、需求、购买力等抽取420份问卷作为样本,分析了峨眉山旅游商品的需求现状,并以旅游者需求现状为依据,对峨眉山旅游商品的开发和营销提出了“4P＋4C＋4R”营销策略,以期对其它景区的旅游商品开发和营销具有一定的借鉴意义。     

Mg3MnxAl1-xCO3类水滑石衍生NSR催化剂的制备及其性能评价

采用共沉淀法合成了三元类水滑石Mg_3Mn_xAl_(1-x)CO_3,通过高温煅烧得到其衍生氧化物Mg_3Mn_xAl_(1-x)O_m,再经浸渍负载Pt或BaO后制得新型NO_x存储/再还原(NSR)催化剂。XRD及SEM表征结果显示,当Mn与Al的摩尔比(Mn/Al)大于1时所制备的Mg_3Mn_xAl_(1-x)O_m有杂晶相出现且发生团聚,结合NO_x存储性能评价结果,确定最优Mn/Al为1。BaO负载不利于NO_x的存储,而当Pt负载量为1%(w)时NO_x存储性能最优,250℃条件下的存储量由负载前的0.52 mmol/g提升至0.61 mmol/g。CO_2与NO_x之间存在较强的竞争吸附。负载1%Pt催化剂的NSR性能评价结果表明,8个稀燃-富燃循环后NO_x的去除率为68%,表明催化剂的还原性能仍需加强。     

Ti3C2纳米层状材料对废水中Cr（Ⅵ）的光催化去除性能

以Ti₃AlC₂为原料,采用HF刻蚀工艺制备出12种Ti₃C₂纳米层状材料,对其形貌进行了表征,并考察了以其作为光催化剂对废水中Cr（Ⅵ）的处理效果。实验结果表明：HF体积分数为80%、刻蚀时间为48 h时得到的MX-80-48的形貌较好;MX-80-48具有类似石墨烯的二维层状结构,纳米层厚度约20~50 nm,孔径2~10 nm,比表面积14.8 m²/g,在400~700 nm可见光范围内表现出强烈的吸光性;当Cr（Ⅵ）的初始质量浓度为40.00 mg/L、MX-80-48投加量为200 mg/L、pH=2、反应时间4 h（暗反应1 h+光照3 h）时,Cr（Ⅵ）去除率可达100%。     

直链烷基苯磺酸盐促进剩余污泥产生短链脂肪酸的研究

采用批试试验的方法研究了十二烷基苯磺酸钠(C12-LAS)对剩余污泥在厌氧发酵过程中产生的短链脂肪酸(SCFAs)的影响.结果表明,C12-LAS的投加极大地提高了剩余污泥厌氧发酵过程中的SCFAs产量.当C12-LAS加入量低于0.1g·g-1时,SCFAs产量随着C12-LAS加入量的增加而增加,然而,当C12-LAS加入量高于0.1g·g-1时,SCFAs产量反而有所降低.从污泥产酸量以及经济成本考虑,C12-LAS的最佳投加量为0.02g·g-1,此时剩余污泥的SCFAs最大产量出现在第6天.进一步的研究表明,C12-LAS不仅促使大量的碳水化合物和蛋白质脱离污泥颗粒并溶解到液相中,而且抑制了产甲烷菌的活性.尽管剩余污泥经历着酸化过程,但由于其释放出大量的NH4 -N,污泥在整个厌氧发酵过程中的pH值逐渐升高.