土地市场扭曲如何影响制造业出口产品质量升级*——基于土地市场交易数据和制造业企业数据的实证分析

地方政府“以地谋发展”的策略在促进各地区制造业大规模集聚和出口贸易快速增长的同时，也势必会给企业出口产品质量带来深刻影响。本文综合利用中国土地市场网城市土地交易数据、中国工业企业数据、中国海关进出口产品数据和中国城市面板数据，实证检验了土地市场扭曲对企业出口产品质量升级的影响，并对其内在机制进行了探讨。研究发现：中国城市建设用地配置存在明显的工业偏向性，进而导致工业用地价格被低估，产生工业用地应得收益大于实际价格的反向扭曲问题。这种反向扭曲可通过抑制技术进步、阻碍产业结构高级化、弱化集聚经济效应等机制显著降低制造业企业出口产品质量。土地市场扭曲对企业出口产品质量升级的影响具有明显的异质性特征。具体而言，土地市场扭曲不利于一般贸易企业与混合贸易企业出口产品质量提升，但对加工贸易企业出口产品质量提升具有促进作用。土地市场扭曲对企业出口产品质量升级的抑制作用由东到西依次递增。土地市场扭曲不利于外资企业和国有企业出口产品质量提升，对集体企业及民营企业的影响不显著。     

Farm Capital Investment and Deviations from the Optimal Path

We identify farms’ optimal investment path in capital assets and compare it with their actual investment to assess the direction and extent of deviation from the optimal investment. A probit model is further used to investigate the determinants of the probability that a farmer over‐ or under‐invests in capital assets. We use a panel dataset of Dutch dairy farms over the period 2003–2013, and find that most farms under‐invest in capital assets during the study period. Although the number of farms that had over‐invested in capital assets is relatively small, these farms account for the biggest share of total investment in capital assets. The probit results show that liquidity, agricultural support payments, age, land tenure and standard output size are important variables explaining the likelihood of over‐and under‐investment.     

一种动态加权的LDPC译码方法

为了加快低密度奇偶校验（LDPC）码的译码速度，有效改善LDPC码的译码性能，针对校验节点更新过程中的对数似然比（LLR）值的大小，设计了一种LDPC码的动态加权译码方法。以IEEE 802.16e标准的奇偶校验矩阵为例，根据LLR值的变化规律，利用增长因子和抑制因子对和积译码算法和最小和译码算法进行动态加权。仿真结果显示，基于动态加权的译码方法相对于传统译码方法误码率都有明显改进，译码复杂度也有所降低。     

Box-Behnken响应面法优化徐长卿配方颗粒挥发油-β-CD包合物制备工艺

为了解决徐长卿挥发油加油难及加入后的稳定性问题,采用Box-Behnken响应面法,优选出徐长卿配方颗粒挥发油-β-CD包合物的制备工艺。在单因素试验的基础上,采用3因素3水平Box-Behnken设计对徐长卿配方颗粒挥发油-β-CD包合工艺进行优选,以挥发油包合率及包合物收率为考察指标,考察挥发油与β-CD比例、包合温度、包合时间对结果的影响。结果表明:优选的包合工艺条件为挥发油与β-CD质量比为1∶8.34,包合温度为50.2℃,包合时间为2.17 h。在此条件下,挥发油包合率为72.19%,包合物收率为75.06%,综合评分为96.41,RSD值为1.1%。优选的包合工艺包合率高,工艺稳定可行,可为配方颗粒挥发油的工业化生产提供数据支持。     

Improving forecasting performance using covariate-dependent copula models

Copulas provide an attractive approach to the construction of multivariate distributions with flexible marginal distributions and different forms of dependences. Of particular importance in many areas is the possibility of forecasting the tail-dependences explicitly. Most of the available approaches are only able to estimate tail-dependences and correlations via nuisance parameters, and cannot be used for either interpretation or forecasting. We propose a general Bayesian approach for modeling and forecasting tail-dependences and correlations as explicit functions of covariates, with the aim of improving the copula forecasting performance. The proposed covariate-dependent copula model also allows for Bayesian variable selection from among the covariates of the marginal models, as well as the copula density. The copulas that we study include the Joe-Clayton copula, the Clayton copula, the Gumbel copula and the Student’s $t$-copula. Posterior inference is carried out using an efficient MCMC simulation method. Our approach is applied to both simulated data and the S&P 100 and S&P 600 stock indices. The forecasting performance of the proposed approach is compared with those of other modeling strategies based on log predictive scores. A value-at-risk evaluation is also performed for the model comparisons.     

战术面向服务架构概念及相关技术

战术面向服务架构（TSOA）是实现战术云平台服务基础设施的重要支撑概念。由于战术环境的复杂性，目前对TSOA实施过程中面临问题和相关实现技术的总结还较少。为此，开展了针对TSOA的概念以及相关技术的研究。首先，从战术环境下的TSOA架构需求背景出发，介绍了TSOA架构的组成以及适应性特征；然后，通过分析战术环境下设备和网络等多方面存在的限制性因素，明确实施TSOA架构所面临的挑战以及需要解决的关键问题，并对实现过程中涉及的服务发现、消息传输机制、网络状态自适应等相关技术进行归纳；最后，对国内外的相关研究工作进行总结，期望对推动TSOA架构的具体实施提供一定参考。     

水源地突发水污染政府应急预留水量需求预测

近年来,随着工业化和产业化的快速发展,水源地突发水污染事件频发。为应对紧急情况下的水资源非常规需求,保障经济社会稳定发展,政府需要安排一部分应急预留水量。如何合理预测政府应急预留水量的规模是一个值得探讨的课题。提出了一种基于案例推理技术的政府应急预留水量需求预测方法,具体思路是:借助于案例库,利用主成分分析法从众多影响水源地突发水污染事件的因素中提取出两两不相关的因子,以此作为案例的特征属性,基于加权曼哈顿距离测算相似度,依此得到匹配案例,进而测算政府应急预留水量。以太湖流域常州地区水源地为例,进行政府预留水量需求量的预测与分析。该方法可以为政府应急预留水量的配置、储备等提供相关理论知识。     

内外融资条件、融资约束与企业绩效——来自京津冀地区企业调查的新证据*

基于独特的京津冀地区企业调查数据和克服内生性的结构方程模型，本文对融资约束的成因及影响进行了实证分析。分析结果表明，企业自身条件和外部市场环境均对融资约束有重要影响，且企业自身条件对融资约束的影响更强。总的融资约束指标对企业绩效的影响不显著。在区分融资约束的不同维度后，本文发现，融资可得性提高显著促进了企业绩效提升，融资频率增加却降低了企业绩效，而融资获得速度（等待时间）对企业绩效没有统计上的显著影响。进一步的分析表明，无论是正规融资渠道，还是非正规融资渠道，上述结论仍然成立。利用多种政策提高企业的管理水平，改善企业的自身条件，是缓解融资约束的最有效办法。     

制度空间下国家级新区空间重构过程与机制--以重庆两江新区为例

制度空间是特定的地理空间中某些被建构并产生有效影响力或影响范围的制度,它是我国国家级新区的重要表征之一,也是推动空间重构的重要因素。建构了"制度空间—行为选择—空间重构"的分析框架,通过实地考察、深度访谈、空间分析相互结合相互佐证的方法,对两江新区的制度空间、主体行为与空间重构的关系进行分析。研究表明:两江新区经历了构想空间、产业空间到消费和居住空间的重构过程,"强激励"与"弱约束"的制度空间扩大了主体行为的空间与资源,是空间重构的内生性力量。地方政府借助制度空间条件,通过空间规模扩张、空间开发垄断和空间场所营销等"理性"行为,在发展初期实现了对空间开发的主导和操纵。随着建成环境的不断完善及地方政府的制度实践,企业"趋利性"投资促进了空间转型和土地升值。原农村居民的"服从配合"和空间让渡助推了空间重构,而不断壮大的富裕和中产阶层通过空间消费,逐渐成为空间重构的积极参与者和受益者。     

Competing with complementors: An empirical look at Amazon.com

Research Summary : Platform owners sometimes enter complementors' product spaces and compete against them. Using data from Amazon.com to study Amazon's entry pattern into third‐party sellers' product spaces, we find that Amazon is more likely to target successful product spaces. We also find that Amazon is less likely to enter product spaces that require greater seller efforts to grow, suggesting that complementors' platform‐specific investments influence platform owners' entry decisions. While Amazon's entry discourages affected third‐party sellers from subsequently pursuing growth on the platform, it increases product demand and reduces shipping costs for consumers. We consider the implications of these findings for complementors in platform‐based markets. Managerial Summary : Platform owners can exert considerable influence over their complementors' welfare. Many complementors with successful products are pushed out of markets because platform owners enter their product spaces and compete directly with them. To mitigate such risks, complementors could build their businesses by aggregating nonblockbuster products or focusing on products requiring significant platform‐specific investments to grow. They should also develop capabilities in new product discovery so that they could continually bring innovative products to their platforms.