Structural response for vented methane–air deflagrations: Effects of volumetric blockage ratio

To investigate the effects of cylinders placed parallel to the venting direction on the structural response of the vessel walls to an explosion, 25 batches of vented explosion tests were conducted in a 1 m³ rectangular vessel. Two types of structural response with different amplitudes and frequency distributions were observed and evaluated by comparing the vibration data with both the pressure data and high-speed videos. A low-amplitude structural response of approximately 150–250 m/s², which increased slightly as VBR increased, was triggered by a combination of the initial flame propagation, external explosion, Helmholtz oscillations, and the Taylor instability. A high-amplitude structural response of approximately 9500 m/s² was also observed, which decreased sharply as VBR increased. Additionally, the high amplitude response was never observed when more than two cylinders were present in the vessel. The high amplitude response was triggered due to the coupling between the acoustic wave, the flame, and the resonance of the vessel. The presence of obstacles did not increase the severity of the structural responses under the current experimental conditions. To the contrary, the presence of obstacles in the container attenuated or even inhibited the high-amplitude vibration of the container caused by the explosion.     

突发环境事件应急监测应对措施分析

在发生突发环境事件事件时,污染事件较为常见,为准确采取应对措施,必须有针对性地开展应急监测,及时采取有效的应对措施。对此,本文首先对突发环境污染事件与应急监测响应概念进行介绍,然后对突发环境事件应急监测准备工作以及应对措施进行详细探究。     

西安市表层土壤和地表灰尘理化性质分析

以西安城市表层土壤和地表灰尘为研究对象,分析其基本理化指标。结果表明,西安市表层土壤pH值的变化范围是7.65~8.54,属弱碱性。地表灰尘pH值的变化范围是6.59~11.19,属碱性。表层土壤的低频磁化率和高频磁化率均值分别为1.55×10^-6 m^3/kg和1.46×10^-6 m^3/kg,频率磁化率均值为6.7%。地表灰尘的低频磁化率和高频磁化率均值分别为5.50×10^-6 m^3/kg和4.84×10^-6 m^3/kg,频率磁化率均值为1.88%。表层土壤和地表灰尘中总有机碳均值分别为1.31%和3.97%。西安城市表层土壤和地表灰尘均主要以粉粒为主,且二者各理化性质之间均有一定的相关性。     

大跨度斜拉桥抗震性能分析与减震控制研究

本文以香溪河大桥为工程背景,利用大型有限元软件ANSYS建立该斜拉桥的有限元模型,进行地震作用下的动力非线性时程分析,并以COMBIN37单元模拟非线性粘滞阻尼器,研究了粘滞阻尼器参数对桥梁抗震性能的影响规律,并确定了合理的阻尼器参数取值。并对未设置与设置粘滞阻尼器的桥梁结构地震响应进行数值分析与比较,分析结果表明:合理设置粘滞阻尼器,可以有效降低桥梁结构关键部位在地震作用下的位移响应,并对结构内力也有一定的降低。本文研究结果为大跨度斜拉桥振动控制分析及工程应用具有重要的指导意义。     

新型三维电化学氧化体系处理压裂返排液

采用不锈钢作阴极、镀钌铱的钛板作阳极、铁碳材料作粒子电极,构建新型三维电化学氧化体系,处理压裂返排液,并通过响应曲面法考察COD去除率和除油率的影响因素。实验结果表明:回归方程的相关系数及校正相关系数均大于0.9,回归方程的线性关系显著;返排液COD去除率和除油率影响因素的大小顺序均为电流电解时间粒子填充比,其中关键因素是电流,电解时间和粒子填充比之间的交互作用具有较大影响;在电解时间为31.8 min、电流为4.4 A、粒子填充比为61.2%的条件下,COD从606.4 mg/L降至68.5 mg/L,含油量从153.7 mg/L降至9.1 mg/L,达到GB 8978—1996《污水综合排放标准》中的一级标准。     

应曲面法优化H2O2催化氧化烟气脱硝工艺

研究了H₂O₂催化氧化烟气脱硝工艺中H₂O₂质量分数、催化剂浓度和溶液pH对脱硝率的影响,采用 Box-Behnken响应曲面法优化了H₂O₂脱硝的工艺条件,得到了相应的数学模型,并进行了方差分析。结果表明,溶液pH、催化剂浓度、H₂O₂质量分数以及催化剂浓度和H₂O₂质量分数的一级交互作用对脱硝率的影响很显著,模型的决定系数为0.995 3,说明模型拟合效果很好。经模型优化分析的最优工艺条件为H₂O₂质量分数0.2%,催化剂浓度0.94 mmol/L,溶液pH 11.0,在此条件下处理进口流量3.5 L/min、 NO体积分数 2×10^-4、O₂体积分数10%、N₂体积分数90%的烟气,液气比为8 L/m³,脱硝率达97%。     

On the selection of stimulus for the auditory variant of the detection response task method for driving experiments

Objectives: The detection response task (DRT) is a method for measuring attentional effects of secondary tasks on a driver's cognitive load by measuring response times and hit rates to different types of stimuli as indirect indicators of increased cognitive load. ISO 17488 (International Organization for Standardization 2016) only provides guidelines for the technical implementation and measurement methods for the visual and tactile versions (use of visual and tactile stimuli) of the DRT method. This article presents a study with the goal of finding the most appropriate auditory stimulus for the implementation of an auditory version of the DRT method.

Methods: This article presents the results of an experiment in which responses to 7 different auditory DRT stimuli—varying in frequency—were compared while inducing users' cognitive load with a modified n-back task. The experiment was conducted in a surrogate driving environment and in a within-subject design. Response times, hit rates, and secondary task performances were observed as indicators of increased cognitive load.

Results: Significantly shorter response times were found for the white noise signal compared to single-frequency signals. However, the largest differences in response times, for trials without and with a cognitive task, were found for 4- and 8-kHz single-frequency signals. No significant differences were found for hit rates and secondary task performances between the different stimuli.

Conclusions: Consistent significant differences in response times for all tested stimuli prove that the auditory DRT variant is also sensitive to changes in cognitive load. The mean increase in response times of more than 25% for 4- and 8-kHz signals for trials with a cognitive task compared to trials without one indicates that one of these signals could be used as a potential auditory stimulus for the auditory DRT variant.     

污染水体中河蚬的生物毒性响应研究进展

河蚬作为广泛分布于世界各国的典型底栖生物,由于其活动性低、滤食性等特征被广泛用作指示生物研究多种水体污染物的生物有效性。但迄今为止,尚没有系统论述污染水体中河蚬生物毒性响应的研究进展。为此,本文从污染物种类、测试指标、试验参数等角度探讨了过去30多年间河蚬在氨、重金属、有机污染物生物富集及生物毒性效应等方面的研究过程及主要成果。以往研究主要以河蚬生物体内累积、形态学及行为学观察、生化指标、代谢组学、基因完整性等指标表征污染水体的生物毒性效应,并随着分子生物学的发展已逐步由多指标全面表征代替单一指标测试。此外,现有研究多偏重于重金属和持久性有机污染物,对氨、新型污染物及纳米材料的河蚬生物毒性效应探讨尚处于起步阶段。河蚬在自然水体污染状况评估、污染水体的生物修复、水体毒性预测等方面具有较高适用性,但河蚬在沉积物毒性鉴定评估(TIE,Toxicity Identification and Evaluation)中的应用研究依然较为缺乏,有待进一步开展。     

Rangeland Fire Protection Associations as disaster response organisations

Rangeland Fire Protection Associations (RFPAs) are volunteer-based groups of trained private landowners who are authorised to respond to events in partnership with governmental agencies. This study analysed the functioning and structure of RFPAs in Idaho and Oregon in the western United States to characterise this under-researched model of disaster response. RFPAs represent an expanding type of disaster response organisation that interfaces with established fire suppression entities, yet ‘emergent behaviour’ manifested in some RFPA response actions. This appeared to lessen and mediate with time, as well as due to recognition of the issues, increased experience of fires, and training that fostered new mutual understandings. There is a need for continued examination of the effect of repeat experience in developing the characteristics of disaster response organisations. In addition, it is crucial to know how the interface between established and other types of organisations may be enhanced to make cooperative disaster response more effective.     

振动试验载荷模拟的动力学原理与工程设计

载荷模拟的精度是振动试验模拟是否有效的决定因素之一.本文根据模态质量分析方法,讨论了基于响应功率谱密度的试验载荷等效性的动力学原理,给出了满足小阻尼稀疏模态特征的结构系统的简化表达式.简支梁和悬臂锥筒的数值模拟分析表明,采用本文方法设计的等效载荷可以取得足够精确的共振响应功率谱密度.