EMI滤波器的设计

文章从建立EMI滤波器的共模、差模噪声源等效电路及电路模型入手,进而探讨了EMI滤波器的设计方法及其在实际应用的结构和结构参数的选择问题。     

数字化转型与企业人力资本升级

企业在数字化转型过程中是否会增加对高技能劳动力的需求,进而优化企业的人力资本结构？基于2013-2020年中国A股上市公司员工雇佣数据,本文对上述问题进行考察并分析其作用渠道。结果显示,数字化转型显著提升了企业本科及以上学历员工的占比,即优化了企业的人力资本结构,且该效应在低融资约束企业、非技术密集型行业和东部地区更为明显。作用机制检验证实,数字化转型显著增加了企业的固定资产投资和研发投资,扩大了企业经营规模,进而促使企业增加对高技能劳动力的需求。进一步研究发现,数字化转型显著提升了企业经营效率,同时增加了高管和普通员工的工资。上述结论表明,企业数字化转型具有技能偏向性特征,有助于企业劳动力结构转型升级。本文研究对数字经济背景下深入理解企业劳动力结构升级变化具有一定参考意义。     

数字时代的银行业变迁——网点布局与行业结构

数字技术可以帮助市场主体重构组织模式,数字经济时代的金融业也因此迎来变革。本文基于2014年至2019年我国县级行政区数据,研究发现,数字金融的发展显著减缓了我国银行业金融机构实体网点的扩张势头,这种效应主要体现在股份制商业银行和城市商业银行上,并主要影响这两类银行的基层机构。同时,我们发现数字金融的发展加快了农村合作金融机构的转型和网点退出,但对国有“六大行”没有显著影响。进一步研究发现,数字金融的影响效果会随着经济发展程度提高和地区金融可得性增加而增强,但随着在位银行的市场势力提升而下降。本文为理解数字经济时代银行业的变迁提供了一定参考。     

消除工频干扰的自适应滤波器

工频干扰是仪器仪表信号中的重要干扰因素，要消除它，人们通常采用滤波方法，而采用自适应滤波的方法，可以取得较好的效果。     

Estimation methods for stochastic volatility models: a survey

Abstract.  Although stochastic volatility (SV) models have an intuitive appeal, their empirical application has been limited mainly due to difficulties involved in their estimation. The main problem is that the likelihood function is hard to evaluate. However, recently, several new estimation methods have been introduced and the literature on SV models has grown substantially. In this article, we review this literature. We describe the main estimators of the parameters and the underlying volatilities focusing on their advantages and limitations both from the theoretical and empirical point of view. We complete the survey with an application of the most important procedures to the S&P 500 stock price index.     

数字化技术作用下产品与服务创新：综述及展望

制造企业服务化过程中伴随着产品创新和服务创新，且两类创新协同演进是推动服务化进程的重要力量。当前，服务化研究大多以此为基点，探讨两类创新的关系，并且随着服务化的“数字化”特征越发明显，大多数学者从技术层面提出数字化技术对两类创新的促进作用。然而，鲜有学者考虑数字化技术对两类创新关系的影响，在一定程度上制约了数字服务化研究与实践。为此，首先通过系统回顾相关文献，分析两类创新的相互作用及其耦合困境；其次，厘清数字化技术促进两类创新的前因、过程与结果，并据此解析数字化技术增强两类创新耦合效应的作用机理；最后，提出该主题未来可拓展研究的三大方向。     

Explicit filters and supply chain design

Due to the complexity of present day supply chains it is important to select the simplest supply chain scheduling decision support system (DSS) which will determine and place orders satisfactorily. We propose to use a generic design framework, termed the explicit filter methodology, to achieve this objective. In doing so we compare the explicit filter approach to the implicit filter approach utilised in previous OR research the latter focusing on minimising a cost function. Although the eventual results may well be similar with both approaches it is much clearer to the designer, both why and how, an ordering system will reduce the Bullwhip effect via the explicit filter approach. The “explicit filter” approach produces a range of DSS designs corresponding to best practice. These may be “mixed and matched” to generate a number of competitive delivery pipelines to suit the specific business scenario.     

The effect of a magazine’s free digital content on its print circulation: Cannibalization or complementarity?

We examine how offering digital content affects demand for print magazines. Using a searchable website archive, we measure the digital content offered by a sample of US consumer magazines from 1996 to 2001. We find strong evidence that digital content cannibalizes print sales. On average, a magazine’s print circulation declines about 3–4% when it offers a website. However, the effect varies with the type of digital content offered. Offering digital access to the entire contents of the current print magazine reduces print sales by about 9%. We find no evidence that digital content complements print magazines. These results are robust to including controls for unobserved magazine, category, and time effects, as well as controls for the impact of contemporaneous price changes and other factors.     

Testing the significance and the non-linearity of the Phillips trade-off in the Euro Area

This paper tests the significance and the non-linearity of the Phillips trade-off in the aggregate Euro Area, in an unobserved components model of stochastic NAIRU and trend output featuring the Phillips equation and the Okun law as main identifying equations, with quarterly data for 1970:I-2002:III. The Phillips curve turns out to be linear and its trade-off statistically significant, while non-linearity shows up in the Okun relation. The results prove to be robust to alternative lag length structures of the model, and to alternative non-linear functional forms. The trend-cycle decompositions estimated with the model capture the main features of the Euro Area’s recent macroeconomic record.First version received: 1 September 2003 / Final version received: June 2004CEMPRE - Centro de Estudos Macroeconómicos e Previsão - is supported by the Fundação para a Ciência e a Tecnologia, Portugal, through the Programa Operacional Ciência, Tecnologia e Inovação (POCTI) of the Quadro Comunitário de Apoio III, which is financed by FEDER and Portuguese funds.We thank comments on earlier versions by Fabio Canova, Miguel St Aubyn, Alvaro Almeida, Pete Richardson, Kevin Ross, and two anonymous referees. We acknowledge James D. Hamilton’s help with the confidence bands. The usual disclaimer applies.     

Forecasting UK house prices: A time varying coefficient approach

Previous studies of UK house prices, developed from the demand and supply ofhousing or from the asset market approach have been poor in terms of robustness and ex-post forecasting ability. The UK housing market has suffered a number of structural changes, particularly since the early 1980s with substantial house price increases, financial market deregulation and the removal of mortgage market constraints through competition. Consequently, models which assume that the underlying data-generating process is stable and apply constant parameter techniques tend to suffer in terms of parameter instability. This article uses the Time Varying Coefficient (TVC) methodology where the underlying data-generating process in the UK housing market is treated as unstable. The estimation results of the TVC regression of UK house prices is compared with those obtained from three alternative constant parameter regressions. Comparisons of forecasting performance suggest the TVC regression out-performs forecasts from an Error Correction Mechanism (ECM), Vector Autoregressive (VAR) and an Autoregressive Time Series regression.