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421.
使用反应路径分析法对Jet-A型航空煤油燃烧的气相燃烧机理进行简化。选用POSF-4658机理作为Jet-A燃烧的详细反应机理,该机理包含1607种燃烧组分、6633个基元反应机理。将飞机防火试验条件作为简化过程的初始条件,得到78种组分,196个反应机理的Jet-A燃烧机理。通过对Jet-A的简化反应机理、详细反应机理和JetA实验数据的比较可以发现,简化反应机理可以较准确地反映Jet-A型航空煤油在防火试验条件下的燃烧特性。利用常用的Jet-A型航空煤油简化机理计算的绝热火焰温度、点火延迟时间及层流火焰速度与本文提出的简化的计算值进行比较。结果表明,提出的简化机理在防火试验条件下具有较高的精确度。得到的Jet-A简化反应机理可为飞机防火试验的仿真研究提供燃烧场的化学反应动力学模型。 相似文献
422.
Baptiste Martinet Simon Dellicour Guillaume Ghisbain Kimberly Przybyla Ella Zambra Thomas Lecocq Mira Boustani Ruslan Baghirov Denis Michez Pierre Rasmont 《Conservation biology》2021,35(5):1507-1518
Climate plays a key role in shaping population trends and determining the geographic distribution of species because of limits in species’ thermal tolerance. An evaluation of species tolerance to temperature change can therefore help predict their potential spatial shifts and population trends triggered by ongoing global warming. We assessed inter- and intraspecific variations in heat resistance in relation to body mass, local mean temperatures, and evolutionary relationships in 39 bumblebee species, a major group of pollinators in temperate and cold ecosystems, across 3 continents, 6 biomes, and 20 regions (2386 male specimens). Based on experimental bioassays, we measured the time before heat stupor of bumblebee males at a heatwave temperature of 40 °C. Interspecific variability was significant, in contrast to interpopulational variability, which was consistent with heat resistance being a species-specific trait. Moreover, cold-adapted species are much more sensitive to heat stress than temperate and Mediterranean species. Relative to their sensitivity to extreme temperatures, our results help explain recent population declines and range shifts in bumblebees following climate change. 相似文献
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424.
Johan Uddling Alan J. Hogg Ronald M. Teclaw David S. Ellsworth 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2023-2031
Rising atmospheric carbon dioxide (CO2) may alleviate the toxicological impacts of concurrently rising tropospheric ozone (O3) during the present century if higher CO2 is accompanied by lower stomatal conductance (gs), as assumed by many models. We investigated how elevated concentrations of CO2 and O3, alone and in combination, affected the accumulated stomatal flux of O3 (AFst) by canopies and sun leaves in closed aspen and aspen-birch forests in the free-air CO2-O3 enrichment experiment near Rhinelander, Wisconsin. Stomatal conductance for O3 was derived from sap flux data and AFst was estimated either neglecting or accounting for the potential influence of non-stomatal leaf surface O3 deposition. Leaf-level AFst (AFstl) was not reduced by elevated CO2. Instead, there was a significant CO2 × O3 interaction on AFstl, as a consequence of lower values of gs in control plots and the combination treatment than in the two single-gas treatments. In addition, aspen leaves had higher AFstl than birch leaves, and estimates of AFstl were not very sensitive to non-stomatal leaf surface O3 deposition. Our results suggest that model projections of large CO2-induced reductions in gs alleviating the adverse effect of rising tropospheric O3 may not be reasonable for northern hardwood forests. 相似文献
425.
426.
为了研究谷物粉尘燃烧特性影响因素,以可食用玉米淀粉为研究对象,通过ZY6243锥形量热仪(CONE)进行了单因素和正交试验,研究了粉尘粒径、惰性介质CaCO3质量分数、热辐射通量对玉米淀粉燃烧特性的影响效应。应用直观分析法和方差分析法定性地研究了各因素对玉米淀粉热释放速率峰值的影响程度并进行了排序,2种方法得出的结论基本一致。研究结果表明:各因素对玉米淀粉热释放速率峰值的影响程度依次为:CaCO3质量分数>粉尘粒径>热辐射通量;其中惰性介质CaCO3对热释放速率峰值和引燃时间的影响最为显著。 相似文献
427.
以122mm钢制药筒装药为研究对象,开展了不同热通量下钢制药筒装药烤燃实验及数值模拟研究。以石膏粉替代发射药,通过烤燃实验研究了122mm钢制药筒内置石膏粉在不同热通量下的温升曲线、温升过程中的最高温度点及其达到发射药热点火温度的时间,并与数值模拟结果对比,得到一定程度上符合较好的结果。通过对数值模拟模型及结果的合理性分析,对122mm钢制药筒内置9/7发射药在不同热通量下的烤燃情况进行了数值模拟,得到不同热通量下钢制药筒装药的燃爆点、燃爆温度及燃爆时间,并得到燃爆温度及燃爆时间与环境热通量的关系,以其为参考,对弹药的日常储运安全及消防安全具有一定的指导意义。 相似文献
428.
为了定量分析省域空间特征区域间的经济增长关系,通过引入场论理论框架,结合集聚经济学和传统空间区域划分理论观点,提出多维旋度大循环经济圈发展模型。定义资金通量经济场,以资金通量流速和资金通量密度为主要测度指标来衡量特征区域的经济学指标。以黑龙江省大循环经济圈发展模式的建设构思检验模型的合理性,并由此得出黑龙江省实现经济再增长的关键问题是要处理好农林产业、能源产业、其他新兴服务产业同外贸产业之间相互触发、互为依存的激励关系。 相似文献
429.
Climate change vulnerability is disproportionately distributed between different population segments in society. This study qualitatively explores how key stakeholders in municipalities (i.e. planning and operational staff in municipalities and the vulnerable themselves) construct social vulnerability in relation to climate change with a specific focus on thermal stress (i.e. heat waves) and which adaptive responses they identify at different levels. The empirical material consists of five focus groups with actors in a large Swedish municipality where the “Vulnerability Factor Card Game” was used as stimulus material to create 10 fictional individuals. The results show that there is a substantial amount of local knowledge about vulnerability drivers and inter-relations between social factors and vulnerability. Local decision-makers also defined a wide range of possible adaptation measures at different municipal levels. Our study clearly indicates that contextualised knowledge, which could complement the quantitative approaches in research, is abundant among municipal planners, staff employed at municipal operations such as health care, and among the vulnerable themselves. This knowledge remains untapped by research to a great extent and only seems to have an insignificant influence on policy-making. In particular, how impacts vary between different social and demographic groups and how adaptation strategies that target the most vulnerable could be defined are of great interest. The present study clearly indicates that social hierarchy may produce increased inequality in the specific context of climate change, vulnerability and adaptive responses at different levels. 相似文献
430.
主要介绍了步入式高低温湿热试验箱的实现方法,对其原理进行了较为细致的阐述。并对其主要组成部分进行了介绍。该试验箱为公路车辆和集装箱等大型设备安全有效地进行各类气候环境试验提供保障。 相似文献