基于实验模态研究的新型节流降压喷注复合消声器

针对节流降压小孔喷注复合消声器进行实验模态研究。由采集力的激励信号和响应信号,对其进行传递函数分析,寻找消声器所有的模态频率和模态振型。这些频率避开了噪声的峰值频率,消声器不易发生共振,抑制噪声辐射,延长消声器的使用寿命。它对寻找消声器的实际特性,设计性能优良的新型消声器提供可靠的参考依据。     

船舶撞击下10 MW单桩基础风机动力响应特性分析

目的 探究风机在遭遇船舶撞击时的动力响应,以及不同工况下的失效模式。方法 采用 SACS 软件,建立DTU 10MW单桩基础风机的动力分析模型,并利用p-y曲线模拟桩土相互作用,计算不同撞击速度、撞击角度、风载方向作用下海上风机的动态响应,探究风机在停机工况和运行工况下的失效模式。结果 风机受风载作用时,最大机舱加速度和塔顶最大位移分别较无风载时增加了8.5%、68.1%。以5 000 t撞击船为例,风机在停机状态下,撞击速度超过2.13 m/s时,风机面临因机舱故障而引发的失效;风机在运行状态下,撞击速度超过1.88 m/s时,风机面临因挠度超过最大允许值而引发的失效。结论 有、无风载时,机舱加速度响应的差异不明显,而有风载时的塔顶位移较无风载时增长明显。根据风机在停机工况和运行工况下的失效模式,提出了相应的船舶撞击速度临界值。     

陆地气溶胶粒子尺度分布的准确描述

利用AERONET 2.0级数据研究了3种主要陆地气溶胶（吸收性,中性和非吸收性）粒子尺度分布的规律.结果表明：当气溶胶的主要成分为小粒子时,细模式气溶胶的中值半径（r_f）和气溶胶总光学厚度（τ_t）的相关性较好,但粗模式的中值半径（r_c）与τ_t相关性较差,且对中性气溶胶表现为负相关,对其他两种类型则表现为正相关;在细模式气溶胶占比减少时,r_f和r_c与τ_t的相关性均减小;不论在何种情况下,r_f与细模式气溶胶光学厚度（τ_f）,以及r_c与粗模式气溶胶光学厚度（τ_c）总保持很高的相关性,且不论哪种气溶胶类型,r_c与τ_c总表示出稳定的负相关.最后讨论了新的气溶胶粒子尺度描述方法对卫星气溶胶性质反演的影响.     

Monitoring toxics by group testing

Monitoring the environment for a large list of organic compounds present at low levels is costly. The primary purpose of such monitoring is to assure that hazardous levels of such compounds are not released into, or present in, the environment. Viewing this as a quality control problem, we suggest that samples from different sources can be composited using group testing procedures prior to analysis. Our purpose is to describe the basic concepts and suggest problems requiring study.     

基于小波变换和模态曲率差的起重机金属结构损伤识别

属于焊接结构的起重机金属结构受交变载荷的影响,随着使用年限的增加,不可避免地会产生裂纹和腐蚀等损伤,从而引发突发性重大断裂事故。为此,基于结构的振动特性及小波变换理论来研究起重机金属结构的早期损伤识别问题,通过改变局部弹性模量模拟不同损伤工况,分析了起重机主梁在不同损伤工况下的动态响应特性。结果表明,小波变换可明显放大不易察觉的损伤突变,模态曲率差具有较好的损伤识别能力,可为起重机金属结构损伤识别提供新的思路。     

两点激励振动试验时结构模态对控制效果的影响分析

飞机外挂等细长体试件的两点激励振动试验方法在国内外已经开始较广泛应用。因试件动力学的复杂特性经常造成两点激励振动试验控制超差甚至无法控制,因此在试验前有必要对试件开展模态等动力学特性分析。针对某模拟外挂的试验件及试验夹具开展了有限元模态分析,在两点激励试验前对试验中容易出现控制超差的危险频率点进行了预判。随后开展的两点激励振动试验结果证明了预判的正确性以及试验前开展动力学分析的必要性。     

Looking forward: Disasters at 40

This paper reflects on contemporary studies of and responses to disasters, highlighting the importance of historical, spatial, and intersectional modes of analysis, and draws on the author's ongoing research on Southern‐led and local community responses to displacement in the Middle East. Acknowledging the plurality of ‘international communities of response’, it begins by critiquing the depiction of selected responses to disasters as ‘positive’ ‘paradigm shifts’, including in reference to the ‘localisation of aid, and the United Nations’ Regional Refugee and Resilience Plan for Syria. Next it turns to three key themes that are central to disasters studies: migration; forced displacement; and Southern‐led responses to disasters. Among other things, the paper argues that exploring the principles and modalities of South–South cooperation, rather than promoting the incorporation of Southern actors into the ‘international humanitarian system’ via the localisation agenda, presents a critical opportunity for studies of and responses to disasters.     

Histopathological and biochemical alterations of the earthworm (Lumbricus Terrestris) as biomarker of soil pollution along Porsuk River Basin (Turkey)

This study investigated biomarker responses of the earthworm Lumbricus terrestris in order to evaluate the soil pollution along Porsuk River Basin. Samples consisted of animals from six sites that are agricultural regions and a forested control. Histopathological and biochemical alterations were examined. Significant histopathological alterations were observed in animals from three of the sampling sites. There was an enlargement of epithelial cell lining, mucus cell hyperplasia and increase in mucus secretion. Circular and longitudinal muscles lost their structural integrity. Chloragogenous tissue was dilated and vocuolized. Necrosis was observed in the cells and tissues of some affected worms. A load of heavy metals in tissues of animals was determined. Heavy metals were found to be accumulated particularly in longitudinal muscles of animals. CAT activity was found to be increased in animals from three of the experimental sites. GST activity was also increased in five sites while it was stable in one site. The results have shown that animals from locations particularly that are close to urbanized and industrialized regions were seriously affected from the soil pollution around the basin. These results are reflecting the biological effects of soil pollution around Porsuk River Basin on the indicator organism L. terrestris and constitute an early warning of ecological change in relation to human health.     

2005~2010年我国自然灾害救助应急响应的时间变化特征

自然灾害救助应急响应是减轻自然灾害风险的重要途径,也是政府的重要职责,2005年被纳入《国家自然灾害救助应急预案》,反映了我国自然灾害救助工作的发展变化和“以预防为主”的应急管理新思路。收集整理2005~2010年国家启动的历次自然灾害救助应急响应情况,对应急响应的时间变化特征进行分析讨论。结果表明：（1）2005~2010年,国家共针对130次重大灾害事件启动应急响应235次,各级别响应的比例与灾害发生的频次比例相当;（2）近年应急响应以洪涝、台风及其引发的滑坡和泥石流灾害为主,高发重发期在汛期（6～9月）,尤以7月为最;而旱灾、低温冷冻和雪灾以及风雹灾害的关键期分别为春夏秋三季、冬春季节和春末夏初;（3）应急响应特征研究启示减灾救灾工作要因时、因地、因灾制宜,并加快基于过程的灾害风险评估和脆弱性机理研究等 .     

Pros and cons of climate change in China

Climate change strongly affected the structure and functions of natural ecosystems,e.g.the vegetation productivity decreased in the Northeast permafrost region due to the higher temperature and less precipitation,whereas in the Tibetan Plateau,the vegetation productivity increased,owing to the improved thermal resource.Climate change led to reduced precipitation in North and Northeast China and thus the reduced surface runoff.The public needs for energy were changed because of climate change,e.g.the shorter heating period in winter.Climate change profoundly influenced human health,pathophoresis and major projects by increasing extreme events,including frequency and magnitude,and causing more serious water shortage.Under the background of climate change,although the improved thermal resources can be helpful for extending the crop growth period,more extreme events may resulted in more instability in agricultural productivity.Not only did climate change indirectly affect the secondary and tertiary industries through the impacts on agriculture and natural resources,but also climate change mitigation measures,such as carbon tax,tariff and trading,had extensive and profound influences on the socioeconomic system.Further analysis indicated that the impact of climate change presented significant regional differences.The impact had its pros and cons,while the advantages outweighed the disadvantages.Based on the above analysis on the impacts of climate change,we put forward suggestions on coping with climate change.First,scientifically dealing with climate change will need to seek advantages while avoiding the disadvantages of climate change in order to achieve the orderly adaptation to climate change,which is characterized with"Overall best,long-term benefit."Second,quantitative adaptation should be given more attention,e.g.proposing operational schemes and predictable goals and using uncertainty analysis on adaptation measures.Third,more active coping strategy should be adopted to enhance China's future comprehensive competitiveness.The strategies include but are not limited to gradually adjusting the industrial structure,intensifying the research and development(RD)of emission reduction technology and actively responding to the influence of carbon tax,tariff and trading on socioeconomic development in China.