涡流室柴油机燃油经济性的分析与评价

以涡流室柴油机工作过程循环模拟计算为基础，定量分析计算了Ｓ１９５柴油机各项热力损失所占的比例及对燃油经济性的影响，为进一步认识涡流室柴油机热力过程的特点和降低涡流室柴油机燃油油耗提供了有益的帮助。     

量纲分析法在等温容器建模中的应用

等温容器是一种新型气动元件流量特性测量装置,建立等温容器数学模型对于预测等温容器性能,合理设计等温容器是十分重要的,分别利用量纲分析法和集总参数法建立了等温容器数学模型并进行仿真与实验对比,结果证实,采用量纲分析法获得的数学模型更为简单且准确度更高,更适用于工程应用,该数学模型为合理设计等温容器提供了理论依据。     

一种高斯色噪声混响背景的宽带信号检测算法

针对由正反线性调频信号和双曲调频信号产生的宽带混响,研究了以局部平稳高斯色噪声混响模型为基础的分段匹配滤波检测算法。对匹配滤波器采用分段预白化处理,对数据进行合理分段后,对每段数据按高斯色噪声背景下的最佳检测器,即对匹配滤波检测器进行预白化处理,则可以得到分段预白化匹配滤波检测器。仿真试验实现了对混响数据下的宽带信号检测。结果表明采用分段匹配滤波器和分段预白化滤波器可以在低信混比下检测信号,其中分段预白化匹配滤波算法可以有效检测满足局部平稳高斯色噪声背景下的回波信号,且性能优于分段匹配滤波器。     

汽油机L型燃烧室入缸截面对充气效率的影响

经过对倒置气门汽油机Ｌ型燃烧室的试验研究，指出入缸截面是影响充气效率的关键因素，入缸截面积与活塞面积之比值的最佳范围在７．５％至８．５％之间。     

有旋流燃烧器的流场研究

采用ｒ－ｚ子午面与ｒ－θ横截面将三维湍流场进行分解,成功地完成了有旋流湍流场的数值计算。比较分析了直射流与有旋射流的燃烧室内流场的特征。     

沉积物对汽油机碳氢排放物形成的预测与实验研究

建立了汽油机燃烧室沉积物处未燃碳氢生成和氧化模型，测量了有、无燃烧室沉积物时发动机排气中的碳氢摩尔浓度．实验结果表明：沉积物的存在将增加发动机碳氢排放量，在本实验用机及实验条件下，沉积物将使发动机排气中的碳氢摩尔浓度增加２０％～３０％．计算结果表明：本模型能较好地预测出沉积物形成的排气碳氢摩尔浓度     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

基于化学平衡的等离子体助燃计算与分析

研究了非平衡等离子体助燃的机理,并用最小Gibbs自由能理论对注入粒子后甲烷的燃烧进行了计算。对注入不同量粒子后燃烧温度和燃烧产物的分析证明,等离子体所具有的化学动力学特性可以加快反应的进行,增加燃烧温度和降低燃烧污染物的排出,从而验证了等离子体在航空发动机燃烧室中助燃的可行性。     

混响室条件下辐射敏感度表征方法研究

为确定混响室条件下辐射敏感度的表征方法,分别对混响室步进模式和连续模式下的电磁环境特征进行分析,得出可能的几种表征方法. 再将某型电子设备分别在两种工作模式下进行电磁辐射敏感度测试,利用几种可能的表征方法分别得出其测试结果,并对各个表征方法进行分析. 基于贝塞尔公式对各个可能的表征方法进行重复性及不确定检测. 结果表明,为了获得良好的测试可重复性及不同模式的测试结果相关性,混响室步进模式时,可采用多个步进位置的平均值作为辐射敏感度的测试结果;混响室工作于连续模式时,应当选择适当的统计平均时间参数对测试结果进行表征.      

圆筒燃烧室旋流流场的研究

本文介绍圆筒燃烧室内双股同心旋转射流物理模型实验与数值模拟的研究结果。数值模拟按著者最近提出的湍流涡量输运方程,采用ψ-ω方法及K-ε湍流双方程模型,Rodi提出的壁函数,以及Spalding教授等提出的计算湍流回流的方法。本文工作表明,用涡量—流函数法及K—ε双方程模型计算强旋流及回流是可行的。