自重湿陷性黄土地基预钻孔浸水处理的可靠度设计方法

为解决传统预浸水法存在的浸水时间长、浸水处理范围难以确定等不足,基于土体中水分运移规律,依据可靠度理论、极限状态设计方法及复合 Poisson 过程原理,提出一种消除黄土湿陷性的处理浸水方法——预钻孔浸水法。给出了利用预钻孔浸水法对自重湿陷性黄土地基进行浸水时,水平向及竖直向浸水影响范围的确定模型;在此基础上结合达西定律给出了浸水孔设计参数如孔深、孔间距及浸水孔个数的确定方法。结合铜川某工程,设计进行了现场预钻孔浸水试验,对该方法的合理性进行了验证,并通过现场钻探、现场勘探、室内湿陷性试验等方法对该方法的处理效果进行了评价。该浸水方法具有浸水时间短、浸水影响范围可根据浸水孔布设进行控制等优点,且浸水处理效果良好,完全符合施工要求。     

南水北调中线总干渠藻类的生态调度

南水北调中线总干渠无在线调蓄水库,对藻类生态调度过程中出现的问题开展生态调度实现策略和实施方式研究。主要实现策略包括:划定自身的调蓄区,隔离生态调度对下游的影响;采用高效的渠池运行方式,减少生态调度时蓄量的反复调整;综合考虑安全、快速、平稳等需求,设定生态调度实施进程和方式。具体实施方式包括:将总干渠划分为流速调控区、调蓄区和正常运行区,分别实施等体积、控制蓄量和闸前常水位方式运行;将生态调度过程划分为充水阶段和泄水阶段,基于流速调控目标值、持续时长和水位降幅约束条件,确定各阶段时长和各分区的闸门群调控方案等。基于2018年3月输水工况,采用明渠一维非恒定流模型,仿真总干渠上游15个渠池的藻类生态调度过程。结果表明,生态调度可在3.5 d内完成,各渠池的平均流速由0.48 m/s增至0.93 m/s,持续时间超过2 h。在整个生态调度过程中,水位变化平稳,水位变幅符合安全阈值要求,下游渠道的正常运行未受生态调度明显影响。     

Institutional dynamics and access to non-farm employment in rural China, 1950–1996

This article examines non-farm employment in the context of Chinese rural institutional change, based on evidence from discrete-time logistic models for event history analysis using the Life History and Social Change survey. We find the transition to non-farm sector rose rapidly during the Great Leap Forward and market reform, while the Cultural Revolution saw it reach the lowest ebb. While male advantage prevailed exclusively during the Cultural Revolution and early marketization, education possessed a stable positive effect in all historical periods. Although the returns to different kinds of political capital vary along with institutional dynamics, intergenerational reproduction was greatly reduced after the Cultural Revolution.     

基于熵权物元模型的长三角幸福河层次评价

将幸福河概念与长江三角洲区域一体化发展战略相结合，基于自然、人类社会、人水关系3个系统构建了包含24个指标的长三角幸福河层次评价指标体系；引入需求层次理论，以基础Ⅰ层次、基础Ⅱ层次、提升Ⅰ层次、提升Ⅱ层次、幸福层次5个层次作为幸福河的层次评价等级，运用熵权物元模型，建立了长三角幸福河层次评价模型，并对2018年长三角三省一市幸福河层次等级进行了评价。结果表明，三省一市均处于转化中的中间状态，其中江苏省向提升Ⅰ层次转化，浙江省、安徽省向提升Ⅱ层次转化，上海市向幸福层次转化，说明区域整体幸福河层次处于较高水平，但稳定性较差。     

生计资本对黄土丘陵区贫困人口生计活动的影响及评价*——以甘肃省榆中县为例

［目的］通过深入研究黄土丘陵区贫困人口生计资本对生计活动的影响，为解决农村贫困问题，提升农户生计资本存量、实现区域可持续生计发展提供科学依据。［方法］文章以甘肃省榆中县为例，基于对榆中县农户的调查数据，采用熵值法分析了东北部山区、中部川区和西南部山区贫困人口的生计资本状况和生计活动方式，并对其生计活动进行评价。［结果］从农户的生计资本组合来看，榆中县整体自然资本和人力资本相对物质资本、金融资本、社会资本3类资本较为富裕，尤其在西南部山区和东北部山区3类资本缺乏型农户比例较高。中部川区各乡镇人口的总体生计资本状况较好，总指数最高，而西南部山区次之、东北部山区最低，两者生计资本状况总体匮乏。农户的生计活动主要以种植、养殖和外出打工为主，生计活动多样性程度偏低； 中部川区人口的生计活动多样性指数最高，西南部山区次之、东北部山区最低，且整体受教育程度偏低，加之物质资本、金融资本、社会资本缺乏进一步限制了当地农户的生计多样性。［结论］（1）针对不同生计资本水平和生计活动多样性程度偏低的贫困地区，需要进一步发挥民族文化产业扶贫优势，开启地域产业扶贫新模式，打造地域无公害特色农业产业品牌，提高农户物质资本边际贡献； （2）发展小额信贷金融服务，改善农户金融资本存量，预防村际农户金融资本二元极化； （3）实施免费教育培训技能学习，打造教育培训脱贫示范村，提高人力资本存量，缓解贫困人口生计压力等提高经济发展水平的扶贫政策措施。     

What has New Zealand gained from The FTA with China?: Two counterfactual analyses†

We investigate the effects of the 2008 New Zealand (NZ)–China free trade agreement (FTA) on exports from NZ to China, and real GDP per capita in NZ using the synthetic control method to estimate the counterfactuals. NZ exports to China were more than 200% higher in 2014 than what they would have had the FTA never been signed. NZ's food and live animals exports to China were more than 180% higher in 2014 than the counterfactual. Our counterfactuals indicate a small but negative effect of the FTA on NZ's real GDP per capita between 2009 and 2012.     

Error analysis of finite difference and Markov chain approximations for option pricing

Mijatovi? and Pistorius proposed an efficient Markov chain approximation method for pricing European and barrier options in general one‐dimensional Markovian models. However, sharp convergence rates of this method for realistic financial payoffs, which are nonsmooth, are rarely available. In this paper, we solve this problem for general one‐dimensional diffusion models, which play a fundamental role in financial applications. For such models, the Markov chain approximation method is equivalent to the method of lines using the central difference. Our analysis is based on the spectral representation of the exact solution and the approximate solution. By establishing the convergence rate for the eigenvalues and the eigenfunctions, we obtain sharp convergence rates for the transition density and the price of options with nonsmooth payoffs. In particular, we show that for call‐/put‐type payoffs, convergence is second order, while for digital‐type payoffs, convergence is generally only first order. Furthermore, we provide theoretical justification for two well‐known smoothing techniques that can restore second‐order convergence for digital‐type payoffs and explain oscillations observed in the convergence for options with nonsmooth payoffs. As an extension, we also establish sharp convergence rates for European options for a rich class of Markovian jump models constructed from diffusions via subordination. The theoretical estimates are confirmed using numerical examples.     

The Non‐Observed Economy in Portugal: The monetary model and the MIMIC model

This paper offers estimations for the Portuguese path of the Non‐Observed Economy (NOE), in the period 1970–2015, through two seminal approaches: monetary method and the Multiple Indicators Multiple Causes (MIMIC) model. It is observed that the tax burden and social benefits are its main causes. Then, to get a more in‐depth understanding of the phenomenon, it provides a study of the Granger causality between the NOE and the official Gross Domestic Product (GDP), emphasizing the implications of the NOE on the Portuguese economy. Evidence has been found for the existence of bidirectional causality between the NOE and the GDP, suggesting that the formal economy affects the NOE, and conversely that the NOE affects the economic growth.     

乌蒙山片区绿色减贫指数分析

[目的]通过分析2012年和2014年乌蒙山片区绿色减贫指数,评价该地区不同年份扶贫效果,这也为今后各项扶贫政策的实施提供理论参考。[方法]文章依据中国绿色减贫指数指标体系,从经济增长绿化度、资源利用与环境保护程度、社会发展能力和扶贫开发与减贫效果4个方面,以人均地区生产总值、单位地区生产总值能耗等27个因子作为评价指标,利用线性加权综合法分析2012年和2014年经济增长绿化度、资源利用与环境保护程度、社会发展能力和扶贫开发与减贫效果指标值,最终确定绿色减贫指数。同时,分析片区内各贫困县波动较大的第三产业增加值比重、单位耕地面积化肥施用量、城乡收入比和农村人均纯收入增长率等指标。[结果]2014年相比2012年,乌蒙山片区经济增长绿化度、资源利用与环境保护程度和扶贫开发与减贫效果指标值上升,社会发展能力指标值降低,绿色减贫指数提高了15.40%。各县第三产业比重均降低,但农村人均纯收入都有提高。四川省10个县单位耕地面积化肥施用量增加。四川省除叙永县和美姑县,贵州省除赤水市,片区内的各贫困县城乡收入比降低。[结论]2014年,乌蒙山区在落实国家扶贫规划上取得了较好的成效。但各县之间差距较大,在今后的扶贫攻坚中,需要从不同地区的实际情况出发,了解贫困类型和贫困程度,考察当地资源储备和环境现状,统筹区域发展。     

基于熵值法的高质量发展综合评价研究

探索高质量发展评价指标体系是当前社会各界面临的极富挑战性和开创性工作。从生产、分配、交换和消费四个环节选取23个指标构建高质量发展指标体系,利用熵值法对2000—2015年我国经济高质量发展进行评价。在此基础上从提升全要素生产率、调节国民收入分配格局、助力文化消费以及防范市场风险等层面提出政策建议。