Persistence Heterogeneity Testing in Panels with Interactive Fixed Effects

We consider large N,T panel data models with fixed effects, a common factor allowing for cross‐section dependence, and persistent data and shocks, which are assumed fractionally integrated. In a basic setup, the main interest is on the fractional parameter of the idiosyncratic component, which is estimated in first differences after factor removal by projection on the cross‐section average. The pooled conditional‐sum‐of‐squares estimate is consistent but the normal asymptotic distribution might not be centred, requiring the time series dimension to grow faster than the cross‐section size for correction. We develop tests of homogeneity of dynamics, including the degree of integration, that have no trivial power under local departures from the null hypothesis of a non‐negligible fraction of cross‐section units. A simulation study shows that our estimates and tests have good performance even in moderately small panels.     

Nonstationary Cointegration in the Fractionally Cointegrated VAR Model

We consider the fractional cointegrated vector autoregressive (CVAR) model of Johansen and Nielsen (2012a) and make two distinct contributions. First, in their consistency proof, Johansen and Nielsen (2012a) imposed moment conditions on the errors that depend on the parameter space, such that when the parameter space is larger, stronger moment conditions are required. We show that these moment conditions can be relaxed, and for consistency we require just eight moments regardless of the parameter space. Second, Johansen and Nielsen (2012a) assumed that the cointegrating vectors are stationary, and we extend the analysis to include the possibility that the cointegrating vectors are non‐stationary. Both contributions require new analysis and results for the asymptotic properties of the likelihood function of the fractional CVAR model, which we provide. Finally, our analysis follows recent research and applies a parameter space large enough that the usual (non‐fractional) CVAR model constitutes an interior point and hence can be tested against the fractional model using a Chi‐squared‐test.     

蒸汽动力系统的综合及操作优化

蒸汽动力系统的综合和操作优化是 2 1世纪石油化工企业节能增效的重要途径。本文概述了蒸汽动力系统的优化方法 ,如过程能量综合技术、数学规划法、遗传算法、模拟退火法等方法的长处和不足 ,提出了蒸汽动力系统的优化策略     

以DCP和DTBP引发制备交联UHMWPE

分别以DcP和DTBP对UHMWPE进行交联改性,通过改变DcP或DTBP的用量、交联温度、交联时间等成型条件制备了模压烧结试样。结果表明：在DcP交联工艺中,DcP与U删1vPE质量比为0．15％、交联温度为155℃、时间为30min时,制品耐磨粒磨损性能最好;在DTBP交联工艺中,DTBP与UHMWPE质量比为O．50％、交联温度为140℃、时间为20min时,制品耐磨粒磨损性能最好。从改进耐磨粒磨损性能角度来说,采用DTBP交联工艺更好。     

柴油机电喷系统中高速电磁铁特性的实验研究

在设计的高速电磁铁特性实验台架上，对柴油机电喷系统中采用的M490F平板型推／拉式高速电磁铁的静态特性和动态特性进行了实验研究，分析总结了电磁铁性能与其结构、使用参数之间的关系。     

基于子域积分的初流量法改进

为提高节点初流量的计算精度,引入子域积分法进行改进。根据自由面与单元的相交情况将单元划分为若干个子域,然后在每个子域布置数值积分点,这就避免了单元内节点初流量被忽略或多计入,也不会出现因自由面在积分点附近的微小移动而引起的节点初流量突变,实现了对单元节点初流量更准确的计算。数值算例表明,改进后的初流量法稳定性、收敛性良好。     

矿井综采工作面自动化系统方案研究

以紫金煤业矿井综采工作面自动化系统作为研究对象,对该矿井的综采工作面自动化系统方案、综采工作面系统集成、数据传输体系和相关软件进行了分析,该研究对矿井综采工作面自动化系统的建设具有一定的指导意义。     

地热能发电的工程技术

概述了地热能及其发电方式和国内外地热能发电的现状,分析了地热能发电的关键技术,讨论了我国地热能发电的工程技术发展方向,提出目前我国地热能发电工程技术的重点是地热发电设备的设计制造技术和成套设备的优化集成.     

Effects of PEMFC operating parameters on the performance of an integrated ethanol processor

In this paper the performance of a complete fuel cell system processing ethanol fuel has been analyzed as a function of the main fuel cell operating parameters. The fuel processor is based on the steam reforming process, followed by high- and low-temperature shift reactors, and carbon monoxide preferential oxidation reactor, which are coupled to a polymeric fuel cell (PEMFC). The goal was to analyze and improve the fuel cell system performance by simulation techniques. PEMFC operation has been analyzed using an available parametric model, which was implemented within HYSYS environment software. Pinch Analysis concepts were used to investigate the process energy integration and determine the maximum efficiency minimizing ethanol consumption. The system performance was analyzed for the SR-12 Modular PEM Generator, the Ballard Mark V fuel cell and the BCS 500 W stack. The net system efficiency is dependent on the required power demand. Efficiency values higher than 50% at low loads and less than 30% at high power demands are computed. In addition, the effect of fuel cell temperature, pressure and hydrogen utilization was analyzed. The trade-off between the reformer yield and the fuel cell performance defines the optimal operation pressure. The cell temperature determines operating zones where the water, involved in the reforming reactions, can be produced or demanded.     

生物法PDO合成PTT结构与性能的研究

采用生物法1,3-丙二醇(PDO)直接酯化缩聚合成聚对苯二甲酸丙二醇酯(PTT),通过IR、1H NMR、DSC 和TG方法对其进行了表征,并与化学法PDO合成的PTT进行比较。结果表明,生物法PDO合成的产物是PTT;生物法PDO合成的PTT比同一纯度的化学法PDO合成的PTT色泽好、粘度大、摩尔质量高,且随PDO纯度提高,PTT粘度、摩尔质量增大;生物法PDO合成的PTT熔点与化学法PDO合成的PTT相差不大,熔融峰比化学法PDO合成的PTT 尖锐,熔融热大,结晶度高;不同PDO合成的PTT树脂热失重相差不大,表明PDO不同对PTT热分解行为影响不大。