Investigation of long-term river water quality variations using different urbanization indices and assessment of common scientific perspectives of urbanization on water quality

This study investigated the water quality variation spanning 30 years (1986–2017) in 16 catchments of Hong Kong against different urbanization indices, namely, built area fraction; population; and product of population and built area fraction. Pearson correlations of three different periods of time (1988–1990, 1998–2000, and 2015–2017) indicated that water quality trends were dependent on the urbanization index. Total solids, nitrite-nitrogen, total phosphorus, electrical conductivity, dissolved oxygen, and flow rate had significant deteriorative trends (Pearson r > 0.5 and p < 0.05) with population and product of built area and population. Results also interpreted that built area fraction and product of built area and population were the worst and best indices that represented urbanization and/or its impacts, respectively. Mann-Kendall test for the entire 30 year period showed that water quality had improved with time with respect to certain water quality parameters (e.g., dissolved oxygen, ammoniacal nitrogen and total suspended solids). The results portrayed that although the urbanization of catchments had increased with time, the river water quality with respect to many parameters showed signs of improvement and the legislative measures implemented seemed to be effective in controlling pollution.     

Temporal trends in agricultural water use and the relationships to hydroclimatic factors in the High Plains aquifer region

The High Plains aquifer (HPA) is the primary water source for agricultural irrigation in the US Great Plains. The water levels in many locations of the aquifer have declined steadily over the past several decades because the rate of water withdrawals exceeds recharge, which has been a serious concern to the water resources management in the region. We evaluated temporal trends and variations in agricultural water use and hydroclimatic variables including precipitation, air temperature, reference evapotranspiration, runoff, groundwater level, and terrestrial water storage across the HPA region for different periods from 1985 to 2020 at the grid, county, or region scale. The results showed that water withdrawals decreased from 21.3 km³/year in 1985 to 18.2 km³/year in 2015, while irrigated croplands increased from 71,928 km² in 1985 to 78,464 km² in 2015 in the entire HPA. The hydroclimatic time-series showed wetting trends in most of the northern HPA, but drying and warming trends in the southern region from 1985 to 2020. The groundwater level time-series indicated flat trends in the north, but significant declining in the central and southern HPA. Trends in irrigation water withdrawals and irrigation area across the HPA were controlled by the advancement of irrigation systems and technologies and the management of sustainable water use, but also were affected by dynamical changes in the hydroclimatic conditions.     

不同警告方式下驾驶人应激反应能力模拟试验研究

为研究在道路突发危险场景下先进驾驶辅助系统的不同警告方式对驾驶人应激反应能力的影响，利用自主开发的驾驶人应激反应能力测试软件，以计算机模拟与驾驶模拟器为试验平台，以实际驾驶视频为试验场景，选取操作准确率和反应时间为测试指标，分析不同警告方式下驾驶人的应激反应能力。研究结果表明:视觉警告可有效缩短应激反应时间；视听觉组合警告中，视觉警告占主导作用，听觉警告起辅助作用；在真实场景视频试验环境下，驾驶模拟器模拟试验的操作效果优于计算机模拟试验。     

THOR dummy chest deflection response in oblique and lateral far-side sled tests

Abstract

Objective: The focus of this study is side impact. Though occupant injury assessment and protection in nearside impacts has received considerable attention and safety standards have been promulgated, field studies show that a majority of far-side occupant injuries are focused on the head and thorax. The 50th percentile male Test Device for Human Occupant Restraint (THOR) has been used in oblique and lateral far-side impact sled tests, and regional body accelerations and forces and moments recorded by load cells have been previously reported. The aim of this study is to evaluate the chestband-based deflection responses from these tests.

Methods: The 3-point belt–restrained 50th percentile male THOR dummy was seated upright in a buck consisting of a rigid flat seat, simulated center console, dashboard, far-side side door structure, and armrest. It was designed to conduct pure lateral and oblique impacts. The center console, dashboard, simulated door structure, and armrest were covered with energy-absorbing materials. A center-mounted airbag was mounted to the right side of the seat. Two 59-gage chestbands were routed on the circumference of the thorax, with the upper and lower chestbands at the level of the third and sixth ribs, respectively, following the rib geometry. Oblique and pure lateral far-side impact tests with and without airbags were conducted at 8.3 m/s. Maximum chest deflections were computed by processing temporal contours using custom software and 3 methods: Procedures paralleling human cadaver studies, using the actual anchor point location and actual alignment of the InfraRed Telescoping Rods for the Assessment of Chest Compression (IR-TRACC) in the dummy on each aspect—that is, right or left,—and using the same anchor location of the internal sensor but determining the location of the peak chest deflection on the contour confined to the aspect of the sensor; these were termed the SD, ID, and TD metrics, respectively.

Results: All deformation contours at the upper and lower thorax levels and associated peak deflections are given for all tests. Briefly, the ID metrics were the lowest in magnitude for both pure lateral and oblique modes, regardless of the presence or absence of an airbag. This was followed by the TD metric, and the SD metric produced the greatest deflections.

Conclusion: The chestbands provide a unique opportunity to compute peak deflections that parallel current IR-TRACC-type deflections and allow computation of peak deflections independent of the initial point of attachment to the rib. The differing locations of the peak deflection vectors along the rib contours for different test conditions suggest that a priori attachment is less effective. Further, varying magnitudes of the differences between ID and TD metrics underscore the difficulty in extrapolating ID outputs under different conditions: Pure lateral versus oblique, airbag presence, and thoracic levels. Deflection measurements should, therefore, not be limited to an instrument that can only track from a fixed point. For improved predictions, these results suggest the need to investigate alternative techniques, such as optical methods to improve chest deflection measurements for far-side occupant injury assessment and mitigation.     

基于多孔环形喷嘴的可燃爆粉尘分散特征的密度效应研究*

为了研究不同密度的可燃爆粉尘在内置多孔环形喷嘴的20 L爆炸特性测试装置中的分散特征，基于负载粒子流方法、耦合DPM动量平衡方程和时间平均 Navier Stokes控制方程组，实现3种不同密度的煤粉、铝粉和锆粉在20 L爆炸测试装置中粉尘分散全过程的数值模拟。研究结果表明:多孔环形喷嘴的分散较为均匀，但是约束管道末端存在局部粉尘残留区，致使爆炸仓内真实粉尘浓度远低于形式浓度；爆炸仓中心位置的最大湍动能随着粉尘密度的增加而减小，只有显著地变化粉尘密度才能展示区分度较高的浓度峰值和抵达浓度峰值的时间。     

瓦斯抽采PC-CAS基封孔材料优化及其膨胀作用分析*

为了研制以硅酸盐/铝酸盐水泥、生石灰、生石膏为主的PC-CAS基封孔材料，采用正交试验优化材料配比、开展膨胀力研究，并用扫描电镜观测料-煤胶结形貌。研究结果表明:材料的最优配比为A2B2C4，其具备优良的流动性、强度及致密性，造浆量达2 100 mL/kg；PC-CAS基材料具有显著的膨胀性，其膨胀力随时间先增大而后趋于稳定，并且该膨胀力随着径向约束的提高而增大；相比于FP材料，PC-CAS基材料产生的膨胀力能够显著降低材料-煤岩界面的空隙并在一定程度上压密煤体内部的裂隙；该材料产生的膨胀力可压密封孔段围岩、提高封孔质量，并为后期“二次注浆”提供保压条件。工业试验结果表明，采用PC-CAS基材料进行封孔可显著改善抽采效果，将原有平均浓度10.11%提升至20.08%。     

汽车道路试验安全管理体系建设研究

为了保障汽车道路试验安全、提高安全管理水平,设计提出汽车道路试验安全管理体系(SMS)总方案。根据OHSAS 18001和安全标准化规范的特点分析,论证了融合两种体系建立道路试验SMS的适用性。并从政策与目标、风险管理、安全保证和安全促进四个模块阐述了该体系的搭建思路、框架内容和搭建步骤。最后,以某自主品牌车企研发中心道路试验的应用情况为例进行效果评估,结果表明:汽车道路试验SMS能有效防控风险、提升试验安全管理水平。     

Laboratory investigation of Waelz slag stabilization

Electric Arc Furnace dusts are considered hazardous waste due to their high heavy metals content (zinc, lead, etc.). The Waelz process is one of the most efficient technologies, in terms of capacity and quality, able to recover nearly the 90% of zinc contained in such EAF dusts. Unfortunately, the resulting slag still has eco-compatibility problems, although its mechanical and chemical properties are suitable for civil engineering applications. Stabilization tests, by quartz addition, were performed on EAF dusts in a laboratory furnace. Temperature, treatment time and cooling rate were varied in order to define the best conditions for regulating the formation of a stable microstructure able to hinder the release of substances. Microstructural characterization was carried-out using SEM and XRD analysis. Leaching tests were performed according to EN 12457-2 standards and water analyses were performed using ICP-OES. The best chemical stability was achieved when dust powders were mixed with 20% of silica and water-cooled.     

硫酸雾测试方法若干问题思考

简述了我国硫酸雾测试方法的发展历史,分析和总结了《固定污染源废气硫酸雾的测定离子色谱法》(HJ 544—2016)存在的一些争议和问题,包括硫酸雾的定义、测试方法的干扰控制等。分析认为,相比《硫酸工业污染物排放标准》(GB 26132—2010),HJ 544—2016对硫酸雾的定义更加合理。实验结果表明:硫酸盐是测试方法条件下的目标物,滤筒可以显著地捕捉硫酸盐。9组样品滤筒中,被测目标物所占比例为7.9%~69.1%;滤筒和前吸收液中,被测目标物所占比例为93.7%~97.8%。HJ 544—2016新增加的两级串联碱液吸收瓶可以较完全地捕集穿透滤筒后的硫酸雾,同时也会捕集SO2。SO2会对硫酸雾测试产生正干扰,约42.9%的SO2在被吸收后转化为硫酸雾。     

长庆油田4731B型非金属集输管道老化特性实验研究

为推广非金属复合管在油田集输油领域的应用，明确其在集输环境中的老化特性是关键问题。基于集输油现场的工程条件，针对长庆油田试用的4731B型钢丝缠绕增强复合管，以采出原油、采出水为实验介质，通过挂片实验、水压爆破实验，借助电镜扫描、拉伸测试对复合管内衬层老化行为、拉伸性能以及复合管极限承压与老化特性进行研究。结果表明:采出原油与采出水均可渗透扩散进入内衬层内部，还会发生局部深入渗透；采出原油、采出水的局部渗透速率分别可达3.4，10.6 mm/a；在某些工况下，内衬层表面产生裂纹；短时间（168 h）内的介质渗透甚至裂纹对其机械性能影响较小，而光氧老化影响显著；现场服役813 d后，复合管极限承压下降2.79%，表明复合管承压性能稳定。