Decomposition of trifluoromethane in a dielectric barrier discharge non-thermal plasma reactor

The decomposition of trifluoromethane (CHF₃) was carried out using non-thermal plasma generated in a dielectric barrier discharge (DBD) reactor. The effects of reactor temperature, electric power, initial concentration and oxygen content were examined. The DBD reactor was able to completely destroy CHF₃ with alumina beads as a packing material. The decomposition efficiency increased with increasing electric power and reactor temperature. The destruction of CHF₃ gradually increased with the addition of O₂ up to 2%, but further increase in the oxygen content led to a decrease in the decomposition efficiency. The degradation pathways were explained with the identified by-products. The main by-products from CHF₃ were found to be COF₂, CF₄, CO₂ and CO although the COF₂ and CF₄ disappeared when the plasma were combined with alumina catalyst.     

热爆炸研究的主题聚类、趋势与影响

为全面认识国际热爆炸研究的主题聚类、趋势与影响,使用科技文本挖掘工具VOSviewer对科睿唯安SCI数据库中的1 415篇热爆炸研究论文进行了分析。结果表明:国际热爆炸研究的热点主要分布在燃烧合成、分解、点火、晶体结构、含能材料等方面;以高频关键词为中心形成了5个主要聚类,分别为热爆炸理论基础、热合成、热分解、热行为及含能材料与晶体结构。主题趋势显示热爆炸研究在整体上首先经历了热爆炸理论基础研究,并渗透到了热合成、热分解、热行为和含能材料与晶体结构等方面,高影响主题集中在热合成和热分解两个领域。热合成研究的高影响主题相比其他领域要更加显著,高影响主题涉及传播、镍铝化物、钛镍、铝、碳化及致密化等方面。相比而言,作为热爆炸研究的基础领域,热爆炸理论研究的热度及对应聚类主题的整体引用次数要显著低于目前活跃的领域。     

中部地区省会城市雾霾污染变化特征研究及因素分解

为了分析中部省会城市大气污染的异同性及影响因素,基于中部省会城市的空气质量监测数据,以AQI为代表指标对中部地区雾霾污染城市间异同性及分布特征进行识别,并在STIRPAT模型基础上构建空气污染影响因素模型,借助固定效应模型及2SLS进行回归分析。结果表明:1)中部省会城市在多年经济的推动下,已逐渐呈现春秋适中,夏冬偏高的污染发展趋势,且经济增长与空气质量呈现倒U形趋势;2)五省省会城市除南昌外,其余四省省会空气污染表现出相似特征,尤以南京、合肥、武汉为甚,其显著性差异值达到0.964、0.879、0.915;3)中部地区跨区域雾霾污染在协同控制时,需要着重关注城市人口的变化趋势、新增建筑面积、工业排放的总量控制等方面,并将其纳入到雾霾污染协同控制体系之中。     

火场环境下无人机热损伤试验研究

无人机(UAV)逐步运用于火场搜救,但同时会因为火场高温而受损,为提高UAV在火场救援中的工作效率,设计一种UAV动态测试平台,开展UAV火场飞行试验;分析火场环境下UAV的热损伤情况,探究UAV在火场中的机身温度变化特征和UAV火场飞行安全距离。结果表明:火场热辐射和热对流是造成UAV热损伤的主要形式;旋翼产生的气流场对UAV机身有较为明显的降温效应,在试验工况下最高有25.6℃的降温作用;UAV与火焰的相对距离减少会增加机身的热损伤,在距离0.8 m处开始发生不可逆热损坏,试验工况下UAV火场飞行的安全距离为0.8 m。     

干水在热环境中的持续作用效果研究*

为研究干水对建筑火灾中高聚物燃烧产生的热危害和烟气危害的影响,采用火焰传播量热仪（FPA）模拟建筑火灾扑灭后的持续热环境,对灭火过程中过量施加的干水对可燃高聚物的持续作用效果进行研究。结果表明:干水能够明显提升可燃物的抗复燃性能以及削弱燃烧过程中的热危害和烟气危害;相比于纯燃料,干水作用下可燃物的点燃时间出现明显的延迟,并且热释放速率和一氧化碳生成速率明显降低,尤其在可燃物燃烧初期,干水还具有显著的抑制烟气生成速率的效果。研究结果可为灾后消防人员的搜救和被困人员的逃生提供一种新的技术方案。     

Decomposition dynamic of higher plant pigments by HPLC analysis

IntroductionHigh performanceliquidchromatographic (HPLC )systemsweredevelopedforhigherplantpigmentsinthelate1970’sandearly 1980’s .Subsequently ,morecomplexHPLCsystemsweredevelopedforchlorophyllsandcarotenoidsfrommicroalgaeandnaturalphytoplanktonpopulations(Gieskes,1991;Hodgson ,1997;Bris,1998) .Bothreversedphaseandnormalphasesystemswereused .TheHPLCtechniquewasusedmorerecentlyforplantpigmentanalysis,andithasledtoasignificantincreaseinseparationandinthenumberofpigmentsthatcanbeidentifi…     

A novel hybrid model for water quality prediction based on VMD and IGOA optimized for LSTM

● A novel VMD-IGOA-LSTM model has proposed for the prediction of water quality. ● Improved model quickly converges to the global optimal fitness and remains stable. ● The prediction accuracy of water quality parameters is significantly improved. Water quality prediction is vital for solving water pollution and protecting the water environment. In terms of the characteristics of nonlinearity, instability, and randomness of water quality parameters, a short-term water quality prediction model was proposed based on variational mode decomposition (VMD) and improved grasshopper optimization algorithm (IGOA), so as to optimize long short-term memory neural network (LSTM). First, VMD was adopted to decompose the water quality data into a series of relatively stable components, with the aim to reduce the instability of the original data and increase the predictability, then each component was input into the IGOA-LSTM model for prediction. Finally, each component was added to obtain the predicted values. In this study, the monitoring data from Dayangzhou Station and Shengmi Station of the Ganjiang River was used for training and prediction. The experimental results showed that the prediction accuracy of the VMD-IGOA-LSTM model proposed was higher than that of the integrated model of Ensemble Empirical Mode Decomposition (EEMD), the integrated model of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), Nonlinear Autoregressive Network with Exogenous Inputs (NARX), Recurrent Neural Network (RNN), as well as other models, showing better performance in short-term prediction. The current study will provide a reliable solution for water quality prediction studies in other areas.     

混凝土箱梁桥零号块水化热过程分析研究

结合黄沙港大桥工程实际,以箱室内外温度测试数据作为边界条件,根据混凝土水化过程的热传导方程,应用有限元分析程序ANSYS,对浇筑期间预应力混凝土连续箱梁零号块结构的温度场进行了仿真分析,并将仿真计算结果与混凝土连续箱梁的实测结果进行了比较。然后,应用ANSYS软件,采用增量法,动态模拟浇筑过程中水化热温度场变化引起的结构应力变化,得到了施工过程中应力场的时间和空间分布规律。分析表明,由于顶板和底板厚度较薄、内外温差较大,温度引起的残余应力也相对较大,而腹板最终的残余应力较小。因此,应该通过覆盖保温材料,控制厚度较薄的底板和顶板的内外温差,以改善内部混凝土后期受力状况,同时要注意控制预应力张拉时间和张拉力的大小。     

烃类池火灾热辐射量化分析模型探讨

为澄清有关烃类池火灾热辐射量化分析模型选择中存在的问题,针对"池火计算方法"模型进行量纲分析和物理意义方面的讨论,提出该模型在概念使用、量纲关系、热释放速率的计算以及池火焰模化等方面存在的问题。系统阐述点源模型、Shokri-Beyler模型、Mudan模型等常用烃类池火灾热辐射通量分析模型的适用条件和应用范围。点源模型适用于被辐射目标物从池火焰接受的热辐射通量小于5 kW.m-2情况下池火灾热辐射的量化分析;Shokri-Beyler模型主要应用于估算被辐射目标物从池火焰接受的热辐射通量大于5 kW.m-2的情况;Mudan模型可用于估算无风或有风条件下被辐射目标物从池火焰接受的热辐射通量。     

火电机组氢冷系统安全评价

国外已经对火电厂的安全评价工作进行了一定的研究,但是国内对此项工作的研究还是比较匮乏,尤其对火电厂危险化学品更缺乏相关的安全评价方法及研究。在火力发电厂实际生产中,需使用到大量易燃、易爆危险化学品,由于使用、存储不当,极易造成重大事故。根据某火电厂实际情况,结合安全评价的基本程序,运用道(DOW)化学火灾、爆炸危险指数评价法对火电机组氢冷系统(GRH)单元进行了评价。结果显示,GRH单元的本质危险性很大,经过安全措施补偿后危险性较轻,说明利用道氏法对火电厂危险化学品使用状况进行评价,能够比较准确地反映被评价单位的实际情况,根据评价结果和存在的问题提出有针对性的对策措施,进一步改善火电机组运行环境的安全。评价结果可为火电厂提高安全管理水平提供有价值的参考。