华能邯峰电厂TTS系统软件优化

邯峰电厂TTS系统(汽轮机跳闸系统)采用的是SIEMENS公司的S5-95F型PLC设备,经过长期运行,暴露出诸多问题。自投产以来,我厂多次因汽机跳闸系统误动引起机组跳闸。因此我厂对汽机跳闸系统的软件部分进行优化,将其容易引起误动的部分进行合理的修改。优化完成后收到了明显的效果,自优化以来运行至今没发生因汽机跳闸系统故障引起的机组误跳闸事故。     

磁致位移传感器在自行火炮性能测试中的应用

介绍磁致伸缩位移传感器的工作原理和小位移参数的测量方法。该传感器有精度高、寿命长、安装简便的特点。对各种位移量变化的测量是自行火炮性能检测的重要内容,针对现有测试方法存在的不足,提出了基于磁致位移传感器的位移量测试系统并应用于自行火炮性能测试中,通过实验得出:该方法使用操作方便、测量准确、自动化程度高,应用范围广。     

从电气角度浅谈1000MW发电机组甩负荷试验

从电气角度阐述了上海漕泾电厂1000MW机组甩负荷试验的具体情况,并针对试验中出现的问题进行了分析。     

膨胀土土体抗剪强度参数测定试样尺寸效应

文章在大量试验资料的基础上,论述测定膨胀土抗剪强度时试样尺寸对抗剪强度参数的影响,从而指出测定膨胀土抗剪强度时的合理试样直径及C、Φ值的确定方法。     

打孔卷烟烟支通风率研究

打孔卷烟的烟支通风率直接影响到烟支焦油的大小,在卷烟打孔接装纸规格及标准一定的情况下,影响烟支通风率大小的主要原因有打孔接装纸的无胶区域、接装纸与胶辊的包角角度,以及接装纸卷曲器上刮刀的角度,通过正交试验的方式对三者进行研究,寻求在给定的烟支通风率条件下,接装纸无胶区域,包角角度、刮刀角度三者的最优组合。通过试验研究,结果表明,接装纸打孔区域无胶区面积140 mm2,包角角度170°,刮刀角度45°,烟支通风率过程控制最稳定,过程控制能力最优。     

Improving the J Test in the SARAR Model by Likelihood-based Estimation

Abstract

It has been demonstrated recently that in small-to-medium samples the empirical significance levels of the asymptotic J-type tests for the SARAR model introduced by Kelejian (2008) can be controlled in many cases by the use of a bootstrap to construct a reference distribution. A feature of the popular GMM estimator in this context that deserves to receive more attention is that in small samples it will often deliver spatial parameter estimates that lie outside the invertibility region of the model. Using such illegitimate estimates to construct bootstrap samples is then problematic; the present paper finds that this practical obstacle may be removed by the use of quasi-maximum likelihood estimates that guarantee invertibility. The effects of different spatial weight patterns and sample size on the empirical significance levels and power of the tests are illustrated, and the paper demonstrates that estimation using QMLE, allied to a simple bootstrap, yields tests with reliable significance levels and reasonable power, in a majority of cases.

RÉSUMÉ dans des échantillons petits à moyens, il est possible, dans de nombreux cas, de contrôler les niveaux à signification empirique des tests asymptotiques introduits par Kelejian (2008) à l'aide d'un ‘bootstrap’. Dans ce contexte, une caractéristique de l'estimateur GMM, très répandu, est qu'il fournit, dans de petits échantillons, des estimations de paramètres spatiaux situés hors de la région d'inversibilité du modèle. L'emploi de telles estimations illégitimes pour la réalisation d’échantillons ‘bootstrap’ devient alors problématique; la présente communication indique que l'on peut supprimer cet obstacle pratique en utilisant le QMLE garantissant l'inversibilité. Les effets des tendances du poids spatial et la taille des échantillons sur les niveaux d'importance et la puissance sont illustrés, et la communication démontre que le QMLE, allié à un simple ‘bootstrap’, permet de réaliser des tests offrant, dans la plupart des vas, des niveaux d'importance fiables et une puissance raisonnable.

EXTRACTO En muestras entre pequeñas y medianas, los niveles de significancia empírica de las pruebas asintóticas de tipo J para el modelo SARAR introducidas por Kelejian (2008) pueden controlarse en muchos casos mediante el uso de un bootstrap. Una característica del popular estimador GMM dentro de este contexto es que en las muestras pequeñas, a menudo producirá estimaciones de parámetros espaciales que están fuera de la región de reversibilidad del modelo. No obstante, el empleo de este tipo de estimaciones ilegítimas para construir muestras bootstrap es problemático; el estudio actual muestra que este obstáculo práctico puede eliminarse mediante el uso del QMLE que garantiza la reversibilidad. Se ilustran los efectos de las pautas de peso espacial y del tamaño de la muestra sobre el poder y los niveles de significancia, y el estudio demuestra que el QMLE, aliado a un bootstrap simple, dota a las pruebas de niveles de significancia fiables y de un poder razonable, en la mayoría de los casos.

     

城乡统筹环境下推动城乡物流一体化发展研究——以浙江松阳县为实证案例

城乡物流一体化是城乡统筹发展的基础性环节,文中选取浙江松阳县为实证案例,运用格兰杰因果检验方法,对城乡物流一体化各影响因素进行评价,结论表明,城乡物流业产值、城乡公路里程、城乡物流量等因素都在不同程度上影响区域经济增长。据此,文中提出了进一步推动城乡物流一体化发展的对策建议。     

Inference on the cointegration rank in fractionally integrated processes

For univariate time series we suggest a new variant of efficient score tests against fractional alternatives. This test has three important merits. First, by means of simulations we observe that it is superior in terms of size and power in some situations of practical interest. Second, it is easily understood and implemented as a slight modification of the Dickey–Fuller test, although our score test has a limiting normal distribution. Third and most important, our test generalizes to multivariate cointegration tests just as the Dickey–Fuller test does. Thus it allows to determine the cointegration rank of fractionally integrated time series. It does so by solving a generalized eigenvalue problem of the type proposed by Johansen (J. Econ. Dyn. Control 12 (1988) 231). However, the limiting distribution of the corresponding trace statistic is χ², where the degrees of freedom depend only on the cointegration rank under the null hypothesis. The usefulness of the asymptotic theory for finite samples is established in a Monte Carlo experiment.     

Sluggish Recovery from the Financial Crisis: Crowding-out Effect and Contagion

Abstract

The stimulus plans by the US Government after the financial crisis in 2008 may decrease private investment by means of a crowding-out effect. The US Federal Reserve utilized quantitative easing policies to maintain the interest rate as low as possible to minimize crowding-out. The 2008 financial crisis also affects other economies through contagion effects. This paper investigates the existence of the crowding-out effect and contagion effect after the crisis using Temin and Voth's models. The empirical results from vector autoregession show that there is a crowding-out effect in the US economy as well as a contagion effect of the crisis on the Korean and Japanese economies.     

城乡固定资产投资差距变化与中国经济增长互动关系研究

以城乡固定资产投资差距变化为视角,利用1980—2010的年度统计数据对经济增长与城乡固定资产投资差距变化关系进行了研究,通过协整分析及Granger因果检验得出结论:经济增长无论在长期还是短期都是城乡固定资产投资差距变化的原因之一,而城乡固定资产投资差距变化仅对短期的经济增长产生影响。基于此,文章提出通过经济增长使偏离的城乡固定资产投资差距实现合理回归以及通过合理的城乡固定资产投资差距促进经济快速增长都可成为政策调控的着力点。