Availability analysis for general repairable systems with repair time threshold

Availability analysis is an important issue in many practical fields. This paper investigates the availability for general repairable systems with repair time threshold. Based on practical applications, a repair time threshold is introduced. If the period of a repair is less than a predefined time threshold, then the system may be considered as working during this period, i.e., the effect of the repair could be neglected. Otherwise, if the period of a repair is longer than the given threshold, then the system is considered as working from the beginning of the system failure until the repair time exceeding the threshold, i.e., the time point of the system down could be delayed. We consider both constant and random repair time threshold. This paper valuates the user-perceived availability, when the user does not experience any service interruption because the duration of repair is too short. The results can be applied in reliability engineering, queueing theory and many other fields. A numerical example for ventilator system is presented to demonstrate the application of the developed approach.     

Does the twin deficit hypothesis hold in the OECD countries under different real interest rate regimes?

This paper explores the validity of the twin deficit hypothesis in selected 25 OECD countries with annual data for 2005–2016 by considering different real interest rate regimes. A non-dynamic panel threshold model, introduced by Hansen (1999), is employed. The novelty of the empirical findings from the present study is that there exists a non-linear relationship between the budget deficit and the trade balance, which is driven by a critical threshold level in the real interest rates. The findings suggest that twin deficit hypothesis holds only under the low real interest rate regime, that is, rises in budget deficits lead to deteriorations in the trade balance when the real interest rate is below the threshold level. When the high real interest rate (i.e. above-the-threshold) regime is concerned, increasing budget deficits give rise to improvements in the trade balance, a finding consistent with the twin divergence hypothesis. Thus, the effect on the trade balance of an expansionary fiscal policy that worsens the budget balance reverses substantially depending on the threshold level of the real interest rates. The major policy implication of this paper is that the policy makers in the selected OECD countries should pay a greater attention to fiscal discipline in order to prevent the trade balance from worsening, because the majority of the countries fall into the low real interest rate regime over the recent years of the sample period (i.e. between 2010 and 2016).     

Estimation of the integrated volatility using noisy high-frequency data with jumps and endogeneity

In this paper, we investigate a new estimator of the integrated volatility of Itô semimartingales in the presence of both market microstructure noise and jumps when sampling times are endogenous. In the first step, our estimation wipes off the effects of the microstructure noise, and in the second step our estimator shrinks the effects of jumps. We provide consistency of the estimator when the jumps have finite variation and infinite variation and establish a central limit theorem for the estimator in a general endogenous time setting when the jumps only have finite variation. Simulation illustrates the performance of the proposed estimator.     

环境管制、知识产权保护与区域创新能力——基于我国省际面板数据的实证研究

文章基于政府主导视角,利用2006—2015年我国30个省级面板数据,构建多元回归模型,分析变量之间的关系.其结果显示,环境管制、知识产权保护与区域创新能力之间呈非线性关系,环境管制与知识产权保护同时实施对区域创新能力有显著的促进作用,且具有区域异质性.从企业生存角度出发,提出门槛效应假说,采用Hansen面板门槛回归模型进行检验.结果表明,在环境管制与知识产权保护共同发挥作用时,环境管制必须控制在合理的范围内.最后采用门槛效应回归方法找到了环境管制与知识产权保护对区域创新能力影响的门槛值,并提出相应的政策建议.     

脱离“贫困陷阱”——以西南H村产业扶贫为例

扶贫背景下,深度贫困地区与其他地区相比,诸多限制性因素导致其自身无法实现跨越式发展,深度贫困群体脱贫存在对起始物质资产和人力资本交织的最低需要,即投入的“关键性门槛”.从长期来看,提高人力资本是脱贫并实现可持续发展的重要途径,在无法实现人力资本短期飞跃的现实情况下,则需要关注深度贫困地区外来物质资产的介入.西南M县H村展开的扶贫实践表明,用外来物质资产暂时替代人力资本,通过人工干预扶贫措施来实现村庄产业扶贫的成效显著,结果显示,H村的产业扶贫不仅带来了主营产业收入,同时也带来了明显的外溢收入,H村采用干预扶贫措施农户的收入显著高于未采用干预扶贫措施的农户.研究表明外部援助对于深度性贫困群体脱贫具有重要意义,同时也意识到摆脱深度贫困这一过程的复杂性,“输血”资源到“造血”功能的转化,需要重视人力资本的提升.     

基于浙江工业企业微观数据的国有资本带动产业升级累计效应分析

使用面板门限模型,通过国有资本比重对绩效影响系数在门限值前后的变化,分析国资带动产业升级作用的累计效果.通过设置虚拟变量区分不同行业类别,考察国资在哪些类别行业中能够起到对于整体的带动(挤进)作用或者挤出作用.实证结果显示,国资比例提高到门限值对于浙江整体企业管理水平有显著正向作用.国资在精细化工和医药等产业中的比例提升对于浙江整体经济的绩效有相比其他行业更加显著的正向作用,而这些行业不是明显的垄断行业.由此得出结论:国资在重点行业中的示范带动作用应该强化,以期累计作用结合混合所有制推进从而达到挤进民资和促进民企产业升级.     

政府减排目标、产业结构与污染减排

政府是污染减排的重要主体,了解其行为对污染减排的作用对提升污染减排效果及实现中国绿色发展具有重要意义。创造性地将政府减排目标纳入研究框架,构建面板门槛模型,从工业污染排放总量的角度分析政府减排目标、产业结构、经济规模等因素对地方污染减排的影响,并用工业污染物强度进行稳健性检验。结果显示,政府减排目标对污染减排的作用存在阶段性不同:经济发展初级阶段,政府减排目标对污染排放总量的作用方向为正; 经济发展水平较高时,作用方向为负; 两者之间存在适应性调整阶段,作用方向具有不确定性,但总体由正向作用向负向作用转变。产业结构对工业污染排放总量的作用方向因污染物种类而异,经济规模对工业污染排放总量作用方向为正。     

Threshold Estimation for Stochastic Processes with Small Noise

Consider a process satisfying a stochastic differential equation with unknown drift parameter, and suppose that discrete observations are given. It is known that a simple least squares estimator (LSE) can be consistent but numerically unstable in the sense of large standard deviations under finite samples when the noise process has jumps. We propose a filter to cut large shocks from data and construct the same LSE from data selected by the filter. The proposed estimator can be asymptotically equivalent to the usual LSE, whose asymptotic distribution strongly depends on the noise process. However, in numerical study, it looked asymptotically normal in an example where filter was chosen suitably, and the noise was a Lévy process. We will try to justify this phenomenon mathematically, under certain restricted assumptions.     

Two-queue polling systems with switching policy based on the queue that is not being served

We study a system of two non-identical and separate M/M/1/? queues with capacities (buffers) C₁ < ∞ and C₂ = ∞, respectively, served by a single server that alternates between the queues. The server’s switching policy is threshold-based, and, in contrast to other threshold models, is determined by the state of the queue that is not being served. That is, when neither queue is empty while the server attends Q_i (i = 1, 2), the server switches to the other queue as soon as the latter reaches its threshold. When a served queue becomes empty we consider two switching scenarios: (i) Work-Conserving, and (ii) Non-Work-Conserving. We analyze the two scenarios using Matrix Geometric methods and obtain explicitly the rate matrix R, where its entries are given in terms of the roots of the determinants of two underlying matrices. Numerical examples are presented and extreme cases are investigated.