极端环境下汽车运行工况的风洞试验对标分析

为比较环境风洞模拟极端环境下汽车运行工况的准确性,设计了实际路试与环境风洞的对标试验,采集了典型高温山区路段汽车的运行数据。通过运动学片段分割以及短行程分析法构造出车辆的行驶工况图。以运动学片段聚类结果所代表的汽车三种运行状态为基础,利用标准化均方误差方法和特征参数值的计算结果对两次试验中汽车行驶工况的关联性与差异性进行具体分析。结果表明：对标试验结果的关联性极强,其细微差异主要体现在第一类运动学片段上,并且频繁的加减速是汽车三种运行状态中对热管理系统升温影响最大的。可见,环境风洞的模拟结果基本上是准确有效的。     

空气/水混合工质制冷循环理论计算

介绍一种混合工质制冷循环,以空气和水两种自然物质的混合物为工质,实现绝佳的环保性能.水的相变改善了空气的压缩和膨胀过程,同时又增加了制冷量,使循环具有很高的经济性.对循环进行了简单的热力分析,并在不同的给定条件下,对各点的状态参数和循环性能参数进行了理论计算.结果表明,在膨胀功充分利用的前提下,环保制冷循环的制冷系数COP=6~7.     

Volatility spillover from the US to international stock markets: A heterogeneous volatility spillover GARCH model

A recent study by Rapach, Strauss, and Zhou (Journal of Finance, 2013, 68(4), 1633–1662) shows that US stock returns can provide predictive content for international stock returns. We extend their work from a volatility perspective. We propose a model, namely a heterogeneous volatility spillover–generalized autoregressive conditional heteroskedasticity model, to investigate volatility spillover. The model specification is parsimonious and can be used to analyze the time variation property of the spillover effect. Our in‐sample evidence shows the existence of strong volatility spillover from the US to five major stock markets and indicates that the spillover was stronger during business cycle recessions in the USA. Out‐of‐sample results show that accounting for spillover information from the USA can significantly improve the forecasting accuracy of international stock price volatility.     

Detecting and Predicting Economic Accelerations,Recessions, and Normal Growth Periods in Real‐Time

The dichotomous characterization of the business cycle in recessions and expansions has been central in the literature over the last 50 years. However, there are various reasons to question the adequacy of this dichotomous, recession/expansion approach for our understanding of the business cycle dynamics, as well as for the prediction of future business cycle developments. In this context, the contribution of this paper to the literature is twofold. First, since a positive rate of growth at the level of economic activity can be considered as the normal scenario in modern economies due to both population and technological growth, it proposes a new non‐parametric algorithm for the detection and dating of economic acceleration periods, trend or normal growth periods, and economic recessions. Second, it uses an ordered probit framework for the estimation and forecasting of these three business cycle phases, applying an automatized model selection approach using monthly macroeconomic and financial data on the German economy. The empirical results show that this approach has superior out‐of‐sample properties under real‐time conditions compared to alternative probit models specified individually for the prediction of recessions and/or economic accelerations. Copyright © 2016 John Wiley & Sons, Ltd.     

湿空气透平循环流程优化分析

从换热器的位置与数目、体现能量的梯级利用原则、减小传热温差、避免带有显著温差的传热过程及充分利用每一个温度等级的能量等方面,分析了循环冷却水非等温混合流程的不足,提出了湿空气透平（ＨＡＴ）循环冷却水等温混合流程,并对该流程的参数进行了优化选择,得出了ＨＡＴ最高热效率循环流程．还分析计算了该循环的热力学性能     

食饵种群具有存放率的第Ⅲ类功能性反应模型的定性分析

本文研究了非密度制约的捕食与被捕食系统中被捕食者种群具有常数存在率的第Ⅲ类功能性反应模型,给出了该系统极限环的不存在性,存在性及唯一性的条件。     

西部凹陷深层沙河街组生储盖组合的层序分析

通过钻井、岩芯和地震等资料的综合分析,可从辽河盆地西部凹陷深层沙河街组中识别出６ 个钻井长期旋回层序和６ 个相对应的地震层序。较为详细地讨论了沙河街组层序与生储盖组合的关系,认为：（１）在以中、长期旋回层序为等时地层对比单元的地层格架中,生储盖组合特征与长期基准面旋回关系最为密切,有利储层发育位置主要出现在基准面上升早中期和下降中晚期,转换处则是烃源岩或盖层的发育位置。（２）各长期旋回层序的生储盖组合具不同的特征,明显受基准面升降的频率、幅度及其所影响的湖平面升降变化速率、相组合、相序、可容纳空间和Ａ／Ｓ值的变化控制。（３）按生储盖组合在垂向上和纵向上的配置关系,可划分为上生下储、下生上储和仅发育储盖的３种基本组合类型,第一种和第二种分别形成于中—高可容纳空间的基准面上升期和下降期,第三种形成于低可容纳空间的基准面完整升降旋回过程中。由第二种与第一种,或第二种与第三种基本组合类型的叠加组成２ 种跨层序发育的复杂组合模式。相对前３种基本类型,复杂组合模式更有利于油气聚集成藏     

一类微分方程极限环的存在性

研究了系统ｄｘｄｔ＝φ（ｙ）－Ｆ（ｘ）,ｄｙｄｔ＝ｈ（ｘ,ｙ）－ｇ（ｘ）的极限环的存在性     

一类非线性系统极限环的存在性

讨论了系统ｄｘｄｔ ＝ φ（ｙ） － Ｆ（ｘ,ｙ） ,ｄｙｄｔ ＝ ｈ（ｘ ,ｙ） － ｇ（ｘ） 的极限环的存在性．     

具有两个不相交抛物线解的中心对称三次系统

本文讨论了具有两个不相交抛物线解的中心对称三次系统,证明了此系统不存在代数分界线环,但可以存在极限环,至少可以存在两个,如存在,它们只可能位于原点的外围．