BLK4-250比例控制器在供水系统设计中的应用

介绍用流量／电流比例控制器取代交流变频调速装置作为高压供水系统的核心部件,通过可编程控制器 (PLC)对工频水泵机组的自动控制作用,消除了由变频器在运行过程中所引发的谐波、喘振、憋压、水锤效应等不利因素的影响,达到了稳定供水压力、节约电能、提高系统可靠性的目的。     

Asymmetric ACD models: Introducing price information in ACD models

This paper proposes an asymmetric autoregressive conditional duration (ACD) model, which extends the ACD model of Engle and Russell (1998). The asymmetry consists of letting the duration process depend on the state of the price process. If the price has increased, the parameters of the ACD model can differ from what they are if the price has decreased. The model is applied to the bid-ask quotes of two stocks traded on the NYSE and the evidence in favour of asymmetry is strong. Information effects (Easley and O'Hara 1992) are also empirically relevant. As the model is a transition model for the price process, it delivers `market forecasts' of where prices are heading. A trading strategy based on the model is implemented using tick-by-tick data.While remaining responsible for any error in this paper, the authors would like to thank R. Anderson, G. Le Fol, C. Gouriéroux, J. Jasiak, W. Pohlmeier, A. Roell, O. Scaillet, S. Wei and three anonymous referees for useful remarks and suggestions on previous versions. The authors would also like to thank A. Ruttiens from KBC-CBC for useful discussions on practical issues related to trading. Support of the European Commission Human Capital and Mobility Program through the network `Econometric inference using simulation methods' is gratefully acknowledged. This paper presents research results of the Belgian Program on Interuniversity Poles of Attraction initiated by the Belgian State, Prime Minister's Office, Science Policy Programming. The scientific responsibility is assumed by the authors.     

基于高频数据的深圳基金市场日内周期性研究

本文利用深市基金指数高频数据,采用Anderson和Bollerslev(1997)提出的弹性傅立叶回归(FlexibleFourierFormregression,即FFF回归)方法首次对深市基金市场进行了日内周期性的研究。通过对高频收益的定性分析,发现基金市场具有同股票市场相似的周期性,并对这一周期性进行了初步的理论解释。通过FFF方法,将该周期因子进行滤波处理以后,基金指数高频绝对收益不再具有明显周期性。FFF回归能较好地确定日内周期因子。     

The Unintended Consequences of the Frequency of PCAOB Inspection

After more than 50 years of self‐regulation of the US auditing profession, the Sarbanes‐Oxley Act of 2002 (SOX) created the Public Company Accounting Oversight Board (PCAOB) as a quasi‐governmental entity with statutory authority to inspect accounting firms that audit public clients. The frequency of this inspection is annual or triennial, based upon the number of public clients the firm audits. We examine the effects of these two levels of inspection frequency on financial reporting quality and audit fees for clients of small and midsize public accounting firms. Our findings provide evidence of significantly higher audit quality and audit fees for clients of annually inspected firms relative to clients of triennially inspected firms. These findings are robust to auditor‐client alignment analyses, propensity score matching, time‐series analyses, examination of firms that have changed from triennial to annual inspection, and particular examination of firms with inspection deficiencies. Overall, our study suggests that the two‐tier frequency system of PCAOB inspection may have also resulted in two‐tier audit quality and audit fee systems for small and midsize public accounting firms, with more frequent inspection leading to more rigorous and informed auditor decisions. We discuss the implications of our results for the Board and the profession at large.     

TACAN信号处理的MATLAB仿真技术分析

介绍了TACAN系统的信号处理及其计算机仿真.利用MATLAB对TACAN信号的中频数字化及基带信号处理过程进行仿真分析,介绍了同相正交积分数字锁相测方位算法并对其进行了仿真验证.     

交叉极化干扰消除技术研究

针对双极化频率复用系统中的交叉极化干扰问题,提出了全数字交叉极化干扰消除 器的设计方案,研制了具有交叉极化干扰消除、解调功能的一体化工程样机。测试结果表明 ,该设备对交叉极化干扰的消除效果明显。     

Time and frequency domain causality Testing: The causal linkage between FDI and economic risk for the case of Turkey

This study aims to explore the causal relationship between economic risk and foreign direct investment (FDI) inflows for the case of Turkey. With the aim of establishing robust findings for the research in mind, both traditional and modern causality techniques are utilized; time domain Granger (1969, “Investigating Causal Relations by Econometric Models and Cross-Spectral Methods.” Econometrica 37: 424–438.), Toda and Yamamoto (1995, “Statistical Inference in Vector Autoregressions with Possibly Integrated Processes.” Journal of Econometrics 66 (1–2): 225–250.), Fourier Toda-Yamamoto and frequency domain Breitung and Candelon (2006, “Testing for short- and long-run causality: A frequency-domain approach.” Journal of Econometrics 132 (2): 363–378.) spectral causality test. Our empirical findings reveal that; economic risk changes in Turkey significantly lead to changes in FDI inflows. However, there is no evidence of causality running from FDI to economic risk. The findings imply that economic risk is an essential determinant of FDI inflows in Turkey. Our findings are compatible with historical macroeconomic developments in Turkey and imply important policy implications. The results of this study can be generalized for other emerging economies that have similar macroeconomic environments, in order to create useful policy implications regarding FDI inflow.     

战场环境中的电波传播模型优化选择方法

针对战场级的复杂电磁环境仿真过程中涉及到全频段覆盖、环境影响、仿真速度要求高等问题,提出了一种综合考虑用频装备、环境信息和模型自身特点的电波传播模型选择方法。该方法首先通过频段对用频装备及电波传播模型进行划分,再结合环境信息中降雨量、海拔、植被覆盖率、气候类型、导电特性等参数进行综合分析,最终得到传播模型的优化选择方案。在典型作战场景仿真应用中,该方法为传播模型的合理选择提供了思路,保证了仿真的精度,同时也为电磁环境仿真中传播模型本地化提供了依据。     

The impact of reverse logistics process coordination on third party relationship quality: A moderated mediation model for multichannel retailers in the fashion industry

Multichannel retailing is a widely adopted strategy in the fashion industry. Companies in this industry find it a source of competitive advantage to invest in reverse logistics infrastructure. However, limited empirical studies investigate the enablers of the relationship quality between the retailers and their reverse logistics service providers. This study quantifies the impact of reverse logistics process coordination between retailers and logistics service providers on relationship quality. Moreover, it tests the mediating role of reverse logistics service quality and the moderating role of conflict frequency in this relationship. Data were collected through a survey using a purposive sample of 241 retail store managers from the fashion retail industry of Pakistan. For this purpose, a self-administered questionnaire was developed using a five-point Likert Scale to gauge the responses. Conditional process analysis was used to evaluate the moderated mediation model. The findings showed a significant positive impact of reverse logistics process coordination on the relationship quality with a logistics service provider, a significant positive mediation effect of reverse logistics service quality, and a significant moderation effect of conflict frequency on the indirect relationship. However, conflict frequency, contrary to the hypothesis in the study, strengthened the indirect relationship. Furthermore, the moderation effect of conflict frequency on the direct relationship was insignificant. This study will help managers better understand the best practices leading to effective management of reverse logistics processes, particularly product returns.     

浅谈高压变频调速系统特点与应用

本文以对某钢铁企业2×360m2烧结机主抽风机电机高压变频调速系统调试为例,阐述了高压变频速系统的分类、特点和应用。