MODELING SOVEREIGN RISKS: FROM A HYBRID MODEL TO THE GENERALIZED DENSITY APPROACH

Motivated by the European sovereign debt crisis, we propose a hybrid sovereign default model that combines an accessible part taking into account the evolution of the sovereign solvency and the impact of critical political events, and a totally inaccessible part for the idiosyncratic credit risk. We obtain closed‐form formulas for the probability that the default occurs at critical political dates in a Markovian setting. Moreover, we introduce a generalized density framework for the hybrid default time and deduce the compensator process of default. Finally, we apply the hybrid model and the generalized density to the valuation of sovereign bonds and explain the significant jumps in long‐term government bond yields during the sovereign crisis.     

一种级联两箱通用数字预失真器及其辨识算法

提出了一种由单形规范线性分段(SCPWL)函数与记忆多项式级联的数字预失真器，并给出了复数域两步最小二乘参数辨识算法。不同于以往一种预失真器适用一种功放模型的情况，所提的预失真算法利用SCPWL函数的分段特性以及记忆多项式的非线性记忆特性，在完成参数辨识的同时自动地调整结构，可适用于传统以及强非线性新型功放模型的线性化补偿。将所提预失真器分别应用于传统记忆多项式、两箱模型以及新型包络跟踪功放。经过计算机仿真，功放输出的幅频特性和频谱曲线表明所提预失真器能够有效地补偿多种功放的非线性特性。算法仿真比较结果也表明，针对包络跟踪功放，所提复数两步最小二乘算法的邻道泄漏比(ACLR)可改善约35 dB，性能优于最小均方(LMS)类算法约30 dB。     

Volatility forecasting: long memory,regime switching and heteroscedasticity

In this article, we account for the first time for long memory, regime switching and the conditional time-varying volatility of volatility (heteroscedasticity) to model and forecast market volatility using the heterogeneous autoregressive model of realized volatility (HAR-RV) and its extensions. We present several interesting and notable findings. First, existing models exhibit significant nonlinearity and clustering, which provide empirical evidence on the benefit of introducing regime switching and heteroscedasticity. Second, out-of-sample results indicate that combining regime switching and heteroscedasticity can substantially improve predictive power from a statistical viewpoint. More specifically, our proposed models generally exhibit higher forecasting accuracy. Third, these results are widely consistent across a variety of robustness tests such as different forecasting windows, forecasting models, realized measures, and stock markets. Consequently, this study sheds new light on forecasting future volatility.     

新形势下我国耕地保护的长效机制研究

耕地是人类赖以生存的物质基础，是国民经济和社会发展的宝贵资源，耕地数量的多少和质量优劣直接关系到国家粮食安全和社会稳定。因此，在新形势下，如何保护好有限的耕地资源，促进经济社会科学、合理地发展，已成为当今世界的重大课题。本文根据我国耕地减少的现实危机及原因，提出一套科学、合理的耕地保护长效机制，力求为进一步有效地保护耕地资源提供理论基础和现实途径。     

半导体存储器及发展趋势

半导体存储器的容量和速度决策着计算机系统运行速度。目前CPU芯片18个月一更新，为了赶上这个速度，半导体存储器的发展也日新月异。     

企业长期激励机制创新

长期激励机制匮乏问题一直是我国理论界和实业界最为关注的核心问题。指出目前在我国实行的长期激励措施的不足,提出了以“股息期权”,代替“股票期权”的激励方案,从而有效解决了我国目前的资本市场和法律法规对于“长期激励形式”的约束,可以为现阶段企业管理者进行薪酬激励机制设计时提供重要的参考和借鉴。     

Memory recall errors in retrospective surveys: A reverse record check study

This paper reports on a study to compare self-reports during an interview with staff who attended a University health centre in Turkey, with the records of visits to the same health centre over the previous 12 months. Design of the study reflects the effects of importance of the event, duration since the event, frequency of the occurrence of the event, measurement scale of the event, and bounded and unbounded recalling. In order to assess the extent of recall error, responses to retrospective questions on health centre visits are compared with administrative records. Statistical models are proposed for short and long term human memory recall error effects on responses.     

建立城市环境卫生长效管理机制

当前各地在改善城市环境卫生中常常不能持久稳定。作者根据实践经验 ,提出建立城市环境卫生长效管理运行机制 :由行政推动转向依法管理 ;由多头管理转向专业管理 ;由政府统包向市场运作转变。     

长大隧道洞口浅埋段施工技术

京包高速公路德胜口隧道出口段为大跨浅埋软弱围岩段,选用合适的进洞方案对保证隧道施工安全和快速进洞有重要意义,文章就该条件下隧道洞口段进洞施工方案进行介绍。     

长期筹资科学化的初步探索--构建最佳资本结构模型

助计算机用定量方法快速有效的解决长期筹资决策问题是知识经济时代对企业的必然要求。最佳资本结构模型用计算机运筹学的方法来决策不同筹资方式的最优筹资额，以帮助企业实现长期筹资目标同时也是财务管理最终目标——企业价值最大化。