Modelling New Zealand dairy products: evidence on export survival and duration

This article presents evidence concerning the pattern of New Zealand dairy exports duration and survival from 1989 to 2017. It also analyses the influence of a set of supply, demand and gravity‐type drivers on the hazard rate for New Zealand dairy export relationships. The findings are summarised as follows. First, New Zealand dairy export relationships are dynamic with numerous entries and exits to and from foreign markets. Around half of the relationships survived for only 1–2 years at the sequence level. Second, duration of sequence, left‐censoring, initial export, decomposed sequences, New Zealand export price index, the number of cows available for dairy production, the number of origins and destinations, and destination partner’s GDP are the most significant factors reducing the hazard rate of export relationships. As regards the effects of the non‐tariff measures, it is interesting that technical barriers of trade are found to significantly decrease the hazard rate. Only pre‐shipment inspection and contingent trade protective measures are significant impediments to New Zealand dairy export relationships. Finally, hazard probabilities for New Zealand dairy export relationships are estimated to be ‘L‐shaped’ over time, whether or not non‐tariff measures are applied to New Zealand dairy products.     

核心企业主导型创业生态系统构成与运行机制:以杭州云栖小镇为例

创业生态系统研究逐渐得到学术界重视,但缺乏基于类型学角度的具体探讨,一直处于抽象层面,这一研究现状不利于理论建构。聚焦核心企业主导型创业生态系统构成、核心企业在创业生态系统运行过程中的主导作用,实证研究国内创业生态系统运行机制,以杭州云栖小镇为案例的研究显示：①核心企业基于自身核心能力及网络中心位置,联合各类主体搭建价值网络体系,通过市场化的网络治理机制与跨界开放式创新,协调多主体在创业生态系统不同阶段、不同层次的复杂交互关系,服务于系统中创业企业发展;②在核心企业主导型创业生态系统平台搭建期,通过创业支持机制发挥主导作用。在组织运行期通过资源承诺机制、全链条孵化机制与网络嵌套机制发挥主导作用。在协同获取期,通过资源共享机制、企业协同机制发挥主导作用。     

Covariance breakdowns and connectedness of crude oil futures markets with non-synchronous data

ABSTRACT

This article identifies the breakdowns in the covariance of three benchmark crude oil futures markets (WTI, Brent and Dubai) and investigates the changes of market connectedness across the breakdown periods. As the crude oil futures are traded in different regions, this article eliminates the non-synchronous trading data by employing the Vector Moving Average structure and the Bayesian data augmentation approach, which keeps the integrity of original data without changing its properties. The results show that there are significant breaks in the covariance structure of crude oil futures markets. The breakdown periods are consistent with the periods when the market volatilities are at high level and the returns are volatile. The changes of market connectedness are independent of the covariance states, which supports the globalization hypothesis for the crude oil market. The results also suggest that there is more information flow out of the WTI than to the WTI during the sample period, particularly during the breakdown periods in 2008–2009.     

GPS-RTK测量技术在长输管道中的应用

在GPS-RTK技术应用方面,本文对GPS-RTK系统的组成、技术特点、工程应用、基本原理做了概述,结合长输管道的特点总结了GPS-RTK数据采集和放样需要注意的问题,分析了转换参数选择的原则,并从实践中得出了几点结论。     

柳钢三炉两机余热电热联产工程控制系统的设计与应用

柳钢锅炉汽轮发电组余热电热联产工程,配套以西门子冗余系统为核心的控制系统设计构架,文章阐述了该系统的软硬件配置、控制系统的功能、控制难点及其实现方法。实践证明,该设计是安全、可靠、稳定的。     

The Reciprocal Relations of Pressure,Work/Family Interference,and Role Satisfaction: Evidence from a Longitudinal Study in Taiwan

The aim of this longitudinal study was to explore reciprocal relationships between work/family pressure, work/family interference, and work/family satisfaction among Taiwanese employees (N = 310). All study variables were assessed three times. We found that within the work domain, earlier work pressure caused later work‐to‐family conflict (WFC), while earlier WFC reduced later job satisfaction. We also found that earlier WFC caused later work pressure, while earlier job satisfaction reduced later WFC. Similarly, we found that within the family domain, earlier family pressure caused later family‐to‐work conflict (FWC), while earlier FWC reduced later family satisfaction. We also found that earlier FWC caused later family pressure. In addition, family pressure and family satisfaction had reciprocal relationships over time. Together these longitudinal and reciprocal relations strongly support our hypothesized feedback loops linking pressure, work and family conflict, and role satisfaction, within each of the work and family domains. We made specific suggestions on breaking these vicious cycles to effectively manage both the work and family roles.     

桩基施工振动对周围环境的影响及防治

随着时代发展,桩基在基础工程中的使用越来越广泛,桩基施工问题也日益突出。概括介绍了桩基施工振动对环境的影响和危害,并详细阐述了打桩时的挤土效应及其对后期土体开挖和桩承载力的影响。最后针对上述危害提出了防治措施。     

回转窑托轮轴瓦发热问题的研究

回转窑作为水泥生产时的"心脏"设备,在使用过程中常常出现托轮轴瓦发热的现象,这是导致回转窑工作效率降低的最直接和最普遍的问题。本文主要从润滑状态和载荷分布情况与两个方面,分析了回转窑托轮轴瓦发热的主要原因,并指出了相应的预防措施。     

基于Labview的油膜涡动和油膜振荡诊断系统的研究

传统的信号处理方法对于非平稳故障信号处理有所欠缺,Hilbert-Huang变换(HHT)能求得的瞬时频率可用于复杂的非平稳信号的分析,得到振幅瞬时频率-时间的分布,准确反映系统的固有特性。本文利用LabVIEW编程平台开发转子振动数据采集分析系统,该系统中的HHT模块能在油膜涡动和油膜振荡故障发生的早期作出准确诊断。     

股票价格服从分数布朗运动的再装期权定价

未定权益的定价是金融工程研究的前沿与热点问题。本文在标的资产的价格服从分数布朗运动的假设下,在风险中性条件下,运用鞅方法,导出了再装期权的定价公式。