Asymptotic comparison at optimal levels of reduced‐bias extreme value index estimators

In this article we are interested in the asymptotic comparison, at optimal levels, of a set of semi‐parametric reduced‐bias extreme value (EV) index estimators, valid for a wide class of heavy‐tailed models, underlying the available data. Again, as in the classical case, there is not any estimator that can always dominate the alternatives, but interesting clear‐cut patterns are found. Consequently, and in practice, a suitable choice of a set of EV index estimators will jointly enable us to better estimate the EV index γ, the primary parameter of extreme events.     

Are microfinance markets monopolistic?

Do microfinance institutions (MFIs) operate in a monopoly, monopolistic competition environment or are their revenues derived under perfect competition markets? We employ the Panzar–Rosse revenue test on a global panel data to assess the competitive environment in which MFIs of five selected countries operate: Ecuador, India, Indonesia, Peru and Philippines, over the period 2005–2009. We estimate the static and the dynamic revenue tests, with analyses of the interest rate and the return on assets. We control for microfinance-specific variables such as capital-assets-ratio, loans-assets and the size of the MFI. The analyses also account for the endogeneity problem by employing the fixed-effects two-stage least squares and the fixed-effects system generalized method of moments. Our results suggest that MFIs in Peru and India operate in a monopolistic environment. We also find weak evidence that the microfinance industry in Ecuador, Indonesia and Philippines may operate under perfect competition.     

A neoclassical interpretation of momentum

The neoclassical theory of investment implies that expected stock returns are tied with the expected marginal benefit of investment divided by the marginal cost of investment. Winners have higher expected growth and expected marginal productivity (two major components of the marginal benefit of investment), and earn higher expected stock returns than losers. The investment model succeeds in capturing average momentum profits, reversal of momentum in long horizons, long-run risks in momentum, and the interaction of momentum with several firm characteristics. However, the model fails to reproduce the procyclicality of momentum as well as its negative interaction with book-to-market equity.     

Taking financial frictions to the data

We estimate a Dynamic Stochastic General Equilibrium (DSGE) model with various financial frictions and analyze how well the model explains the Great Recession. Predictive analysis shows that the model can only slightly better explain the large deviation from trend during the crisis relative to a model without financial frictions. Specifically, the risk premium shock, which is a shock to the external finance premium of the entrepreneurs׳ leverage, explains the largest part of the investment downfall during the crisis. However, the ‘balance sheet’ channel of financial frictions in the model, which structurally links balance sheet conditions of financial intermediaries and nonfinancial borrowers to their borrowing rates, is estimated to be weak. We examine alternative prior specifications for how the financial frictions enter the model and continue to find a limited role for these frictions. Rolling-window estimation provides evidence for substantial time variation in parameters governing financial frictions. We conclude that the well-known financial frictions studied in this paper are not able to explain the financial crisis in a linearized and estimated model.     

状态监测与故障诊断技术在化工设备维护中的应用

良好的设备状况是化工装置连续性生产的必要保障,东昊公司表活剂分公司在设备维护、检修方面运用了先进的状态监测与故障诊断技术,提升了设备管理水平、提高设备检修质量,达到零计划外停车,取得了良好的经济效益。     

电力变压器故障检测技术

电力变压器是电力系统中的主要设备,它是否正常运行直接影响电能的转换和控制,也直接影响系统的安全运行。在运行中,怎样准确检测变压器的潜伏性故障,为变压器的检修及故障处理提供科学的依据,对保证变压器安全运行具有重要意义。     

基于小波变换和曲线拟合法的柴油机故障诊断

为了对柴油机故障类型进行准确诊断,对柴油机缸盖振动信号进行特征提取,所测取的信号通过小波变换提取时域、频域特征参数,得到相应的拟合曲线并计算多项式系数。设定两种常见故障,通过比较其小波变换拟合多项式系数与标准模式间的距离,从而判断出故障类型。经过验证,所判断出的故障类型正好为所设定的故障,由此表明该方法具有很大的优越性。     

浅谈变压器保护

变压器是电力系统中极为重要的装置,其正常运行直接关系用电设备的安全,还关系到用户的生产和生活用电。本文分析了变压器运行过程中的常见故障,并提出了变压器保护措施。     

高邮凹陷沙埝南—永安地区戴一段油气成藏期次综合研究

本文先用圈闭形成期法、烃源岩主生烃期法、饱和压力法得出研究区油气成藏的大致年代,然后根据包裹体均一温度法确定油气充注的具体期次,最后综合分析得出研究区三期成藏的结论。     

电流法找故障在电加热流程的应用

树状电加热流程技术在油田进行了应用,随着电伴热数状流程使用年限的延长,故障频次有增加的趋势,尤其是进入冬季后,电加热管线出现问题后,线路断点确定不准,挖沟机挖不动,必须用人工挖坑,处理难度大,时间长,严重影响原油产量。本文主要对电加热流程运行存在问题进行分析,并提出解决问题的对策,同时对试验所取得的几点认识进行总结,为大庆外围油田推广提供一些经验。