随机分形思想对农村经济合作组织建设的启示

农村经济增长乏力 ,已成为我国经济发展最重要的问题之一。本文通过对农村经济合作组织建设必要性的分析 ,指出了农村经济合作组织建设在农村经济发展及农村居民收入水平提高中的重要作用 ;并结合随机分形思想 ,提出了发展农村经济合作组织的若干思路 ;最后 ,指出了促进农村经济合作组织建设过程中应注意的几个问题。     

论发展低碳经济的减排政策工具

为解决温室气体排放的外部性问题,各种减排政策工具应运而生。根据作用效果的不同,可分为抑制排放的政策工具和鼓励促进低排放的政策工具。在抑制排放的政策工具中,碳税和碳排放交易采用了不同的政策机理,碳税更适用于市场机制不完善的发展中国家,而碳排放交易则更适用于市场机制比较完善、经济发展成熟的发达国家。在鼓励促进低排放的政策工具中,通过综合运用财政补贴、税收优惠和差别定价等措施,对可再生能源的发展可发挥重要作用。     

农机服务发展与粮食生产效率研究:2004—2016——基于变系数随机前沿分析

采用“两步法”研究了农机服务发展与中国粮食生产效率的关系.基于2004-2016年全国31省份粮食生产投入产出的面板数据,利用变系数随机前沿分析方法测算了中国粮食生产的技术变化、技术效率以及全要素生产率,然后构建农机服务发展影响粮食生产效率的OLS回归模型.结果表明:(1)31省份粮食生产的投入要素产出弹性和技术效率存在明显差异,2008年粮食技术变化最为明显,粮食全要素生产率的增长在2008年高达5%.(2)农机服务在2008年以后对粮食全要素生产率的增长具有显著的促进作用,农机服务对粮食TFP的作用存在一定的滞后效应.(3)农机服务发展与劳动产出弹性具有替代关系,与化肥和机械产出弹性具有互补关系.在三大粮食作物中,小麦机械化程度最高,水稻和玉米的机械化程度还有待提升.     

我国农村流通产业技术效率及其影响因素——基于随机前沿模型的分析

采用超越对数生产函数的随机前沿模型,基于2000~2009年我国省级面板数据,测算了我国农村流通产业的技术效率,并考察了我国农村流通产业技术效率的影响因素。实证结果表明:我国农村流通产业存在显著的技术非效率现象,但这种非效率现象有降低的趋势,地区间农村流通产业效率差异也有逐步缩小的趋势。研究认为,完善农村基础设施、增加农村公共服务供给有助于提高农村流通产业技术效率水平。     

对RC4算法的错误引入攻击研究

错误引入攻击假设攻击者可以向密码设备(智能卡)引入错误,使其出现错误的加密结果。攻击者同时利用正确的和错误的加密结果来发现隐藏在密码设备中的秘密信息(密钥)。该文给出了一种对RC4算法的错误引入攻击方法。模拟实验表明,一轮攻击有可能找出RC4初始状态中3个位置的值,连续使用该算法能以较高(大于1/2)的概率恢复RC4的整个初始状态。恢复整个初始状态所需的密钥字个数约为O(216),引入的错误数量约为O(216)。     

Reconstruction of populations by stochastic optimization: Sensitivity analysis

The reconstruction of populations by stochastic optimization solves the nontrivial problem of finding demographic flows from population registers or vital statistics and censuses, if available. These flows allow the reconstruction of stocks (age pyramids and vital statistics). After a review of reconstruction methods, the sensitivity analysis shows the robustness of the method by stochastic optimization to flawed or missing values, to the length of the reconstruction period, and to variations in the actual demographic flows.     

基于潜类别随机前沿的区域创新效率及其影响因素分析

运用可根据研究对象的潜在属性内生分组的潜类别随机前沿模型,采用1999-2012年中国各省区数据,研究各省区的创新效率及影响因素。结果表明:以人力资本水平和基础设施状况为条件变量,将全国各省区分成两个技术类别,分别有各自的技术前沿和函数形式,A类别中上海市的创新效率最高,B类别中河北省的创新效率最高;平均来看,各类的创新效率均呈上升趋势,贸易开放、产业结构和金融发展对创新效率均有显著的正向作用,同时创新效率在各类内部均存在俱乐部收敛。     

Peter Schmidt: Econometrician and consummate professional

Peter Schmidt has been one of its best-known and most respected econometricians in the profession for four decades. He has brought his talents to many scholarly outlets and societies, and has played a foundational and constructive role in the development of the field of econometrics. Peter Schmidt has also served and led the development of Econometric Reviews since its inception in 1982. His judgment has always been fair, informed, clear, decisive, and constructive. Respect for ideas and scholarship of others, young and old, is second nature to him. This is the best of traits, and Peter serves as an uncommon example to us all. The seventeen articles that make up this Econometric Reviews Special Issue in Honor of Peter Schmidt represent the work of fifty of the very best econometricians in our profession. They honor Professor Schmidt's lifelong accomplishments by providing fundamental research work that reflects many of the broad research themes that have distinguished his long and productive career. These include time series econometrics, panel data econometrics, and stochastic frontier production analysis.     

Construction Safety Risk Modeling and Simulation

By building on a genetic‐inspired attribute‐based conceptual framework for safety risk analysis, we propose a novel approach to define, model, and simulate univariate and bivariate construction safety risk at the situational level. Our fully data‐driven techniques provide construction practitioners and academicians with an easy and automated way of getting valuable empirical insights from attribute‐based data extracted from unstructured textual injury reports. By applying our methodology on a data set of 814 injury reports, we first show the frequency‐magnitude distribution of construction safety risk to be very similar to that of many natural phenomena such as precipitation or earthquakes. Motivated by this observation, and drawing on state‐of‐the‐art techniques in hydroclimatology and insurance, we then introduce univariate and bivariate nonparametric stochastic safety risk generators based on kernel density estimators and copulas. These generators enable the user to produce large numbers of synthetic safety risk values faithful to the original data, allowing safety‐related decision making under uncertainty to be grounded on extensive empirical evidence. One of the implications of our study is that like natural phenomena, construction safety may benefit from being studied quantitatively by leveraging empirical data rather than strictly being approached through a managerial perspective using subjective data, which is the current industry standard. Finally, a side but interesting finding is that in our data set, attributes related to high energy levels (e.g., machinery, hazardous substance) and to human error (e.g., improper security of tools) emerge as strong risk shapers.     

On tail behaviour of kth upper order statistics under fixed and random sample sizes via tail equivalence

For a fixed positive integer k, limit laws of linearly normalized kth upper order statistics are well known. In this article, a comprehensive study of tail behaviours of limit laws of normalized kth upper order statistics under fixed and random sample sizes is carried out using tail equivalence which leads to some interesting tail behaviours of the limit laws. These lead to definitive answers about their max domains of attraction. Stochastic ordering properties of the limit laws are also studied. The results obtained are not dependent on linear norming and apply to power norming as well and generalize some results already available in the literature. And the proofs given here are elementary.