Towards an optimised lab procedure for long-term oxidative ageing of asphalt mix specimen

Ageing of bitumen leads to increased stiffness and brittleness. Thus, bituminous bound pavements become more prone to failure by low-temperature and fatigue cracking. Therefore, the ageing behaviour of bitumen has a crucial impact on durability, as well as recyclability of pavements. To assess ageing of bitumen, the rolling thin film oven test and pressure ageing vessel are standardised methods for short-term and long-term ageing in the lab. For lab-ageing of hot mix asphalt (HMA), various methods have been developed in the last decades. This paper presents a study on the potential of employing a highly oxidant gas for simulating the long-term oxidative ageing of asphalt mix specimens in the lab. Based on the results, an optimised lab-ageing procedure (Viennese Ageing Procedure – VAPro) for compacted HMA specimens to assess mix performance of long-term lab-aged specimens is developed. Thus, it is possible to optimise mix design not only for short-term performance but to take into account effects of oxidative ageing during its in-service life. VAPro is based on a triaxial cell with forced flow of a gaseous oxidant agent through the specimen. The oxidant agent is enriched in ozone and nitric oxides to increase the rate of oxidation. It is shown by stiffness tests of unaged and lab-aged specimens, as well as by Dynamic Shear Rheometer tests of recovered binder from aged specimens that asphalt mixes can be long-term aged at moderate temperatures (+60°C) and within 4 days and a flow rate of 1 l/min by applying VAPro. Thus, an ageing procedure is at hand that can simulate long-term ageing at conditions that are representative of conditions that occur in the field within an efficient amount of time.     

沼液预处理最优混凝搅拌条件的研究

通过混凝法对沼液进行预处理最优条件的研究,为沼液预处理提供参考。在实验室条件下,对COD、TN、TP、色度和SS的去除率综合评价混凝工艺效果。实验中依次进行混凝剂投加量、助凝剂投加量、pH和搅拌强度的单因素实验,进而通过正交实验确定沼液预处理最优的混凝搅拌条件。试验结果表明:PAC投加量为4 g/L、PAM投加量为50 mg/L、搅拌速度为200 r/min、混凝阶段同时投加PAC和PAM,处理后的水样COD、TN、TP、色度和SS分别为216.20、181.99、0.18、11.77和71.67 mg/L,去除率分别达到92.51%、88.85%、99.75%、98.37%和89.46%,达到畜禽养殖业污染物排放标准(GB18596-2001),减轻了后续污水处理的负荷,为沼液实际处理提供了理论支持。     

Absorption of ethylene from ethylene‐ethane gaseous mixture by AgNO3 solution in a semi‐continuous process

Ethylene absorption from an ethylene–ethane gaseous mixture in the silver nitrate solution is studied at different temperatures and concentrations. Unlike the previous studies, in which the absorption was studied by batch processes, a semi‐continuous process is applied in the present research. The results show that increase in temperature reduces the amount of absorbed ethylene and absorption time. The amount of absorbed ethylene is increased in solutions with higher concentrations of AgNO₃, whereas the mole ratio of absorbed ethylene per silver nitrate is decreased by increasing the AgNO₃ concentration. Total absorption is modelled as a function of the temperature and concentration of absorbing solution. The estimated values from the model are in good agreement with the experimental data.     

非对称复式断面明渠中污染物输移扩散的大涡模拟

运用大涡模拟计算了两个非对称复式断面明渠内的水流运动和污染物扩散，其中由亚格子尺度涡运动引起的亚格子应力与物质扩散通过Smagorinsky-Lilly亚网格模型模拟。预测结果与Shiono等使用激光多普勒流速计(LDA)和激光诱导荧光技术(LIF)测量的实验数据进行了对比，计算得到的流场结构和污染物浓度分布均较好地吻合于测量结果。成功地再现了在其中一个复式断面明渠中观测到的横向浓度分布呈现显著双峰值的现象，根据计算的流场得出复式断面明渠中流向交替变化的强烈横向流动是产生这种现象的主要原因。     

Development of methods for evaluating hydrogen compatibility and suitability

The embrittlement of metals exposed to hydrogen environments is well documented. With the deployment of hydrogen fuel cell vehicles in the consumer sector, there is a need to improve the engineering basis for the selection of materials of construction for equipment that stores and distributes high-pressure gaseous hydrogen. This brief overview summarizes publicly available guidance for evaluating materials compatibility with high-pressure gaseous hydrogen. Additionally, a new standard for measuring engineering data in gaseous hydrogen and evaluating materials suitability for service in gaseous hydrogen is introduced: the CHMC1 standard provides a general framework for qualifying materials for hydrogen service. The CHCM1 standard is unique in its broad scope and performance-based strategy for quantitatively assessing materials in their service environment and for the intended structural requirements.     

黄河多泥沙水体石油污染物自净实验研究

针对黄河泥沙对石油污染物的迁移转化影响这一突出特点 ,运用模拟实验方法 ,探讨了泥沙对石油污染物的吸附及石油污染物的挥发自净规律。实验结果表明 :泥沙对石油污染物的吸附速度很快 ,吸附量随着温度增加而降低 ,石油污染物具有很强的挥发自净能力。     

液压传动系统油液污染分析与控制

为了提高液压系统的工作效率,分析了液压系统油液污染的起因及危害,介绍了污染物分析及测定的方法,论述了油液污染控制的一般方法,以确保机器液压和润滑系统的正常可靠运行。     

颗粒长大模型在气相爆轰合成纳米材料中的应用

气相爆轰过程是一个相当复杂的瞬态物理化学变化过程,目前实验条件还无法观测爆轰过程中的具体变化,因而常常需要借助于数值模拟辅助理论和实验研究。本文以气相爆轰合成纳米二氧化锡为例,将Kruis颗粒长大模型应用于预测气相爆轰法制备纳米氧化物颗粒直径的研究中。通过研究压力与温度之间的转化关系,建立爆轰条件下的颗粒长大模型,计算出颗粒直径并与实验结果进行对比,以期可以通过合理的模型对其直径进行预测,并为最终人为控制爆轰法制备纳米氧化物颗粒直径的大小奠定基础。     

火电厂NO_x排放在线监测研究

针对现有NOx排放在线监测系统无法准确、完整反映火电厂脱硝设备及排污状况动态变化的问题,建立了一种远程NOx排放实时在线监测系统,分析了系统的构成、数据采集及主要计算指标,并全面展示了系统的应用功能。火电厂NOx排放在线监测系统在采集火电厂侧烟气排放CEMS数据的基础上,全面采集了脱硝系统的设备运行数据,统计分析更加准确;系统以脱硝工艺流程实时展示单台机组的脱硝状态,配合关键指标刷新监测及数据超限报警进行全面NOx排放在线监测;采用统计报表平台实现实时数据及统计指标的及时处理;实时数据库与关系数据库相结合的数据存储方式保证了平台监测数据的透明、公开、公正。目前火电厂NOx在线监测系统已在某发电集团得到应用,实现下属火电机组污染物排放的实时监管,完成污染物排放数据的统计和分析,促进节能减排。