全货运航空公司单分配严格枢纽航线网络优化设计

针对全货运航空公司，研究其货运航线网络的构建问题。基于单分配严格枢纽航线网络，对传统模型进行改进。以各航线上货物的委托运输成本和自有机队的运输成本，取代传统的单位运输成本和折扣因子，考虑枢纽点的中转成本和载运率对路径选择的影响。结合航空货运夜航的特征考虑各机队夜间可用时间的限制，以总成本最小为目标，构建数学模型，采用LINGO优化软件求解，验证模型的有效性，为全货运航空公司构建货运航线网络提供参考。     

森林食品产业减贫的作用机理及效应分析

首先,介绍森林食品产业减贫的作用机理,主要包括解决资源落后与发展滞后的矛盾;促进贫困地区收入增长;注重多方交流互动。其次,将森林食品产业的减贫效应分为社会减贫效应、经济减贫效应、生态减贫效应这3个部分。最后,提出加强基础设施建设与品牌宣传;增加产业联动效应;持续带动地区增收等建议,以期为政府相关部门制定政策提供决策依据。     

Does air pollution change a firm's business strategy for employing capital and labor?

We examine the impact of air pollution on a firm's capital-labor ratio. We propose the hypothesis that, in dealing with air pollution, a firm responds strategically by using relatively more capital and less labor to contain labor costs and remain competitive in the market. Using a sample of Chinese firms and a satellite-based air pollution metric, we test this hypothesis, and our results confirm it. In addition, we document that the impact of air pollution on the capital-labor ratio is more salient for firms with high economic incentives and close monitoring. Further, we report that to respond to worsening air pollution, a firm uses more capital and substitutes lower-quality labor with more high-quality labor. Finally, after increasing the capital-labor ratio, a firm's value increases, in terms of Tobin's Q, suggesting that the adoption of a higher capital-labor ratio, due to air pollution, is a sound business strategy.     

加强人防工程安全管理工作的探讨

国防工程发展建设至今,基本已经趋于健全,其包含万千,由众多部分组成。在国防工程的众多组成部分之中,对于城市以及民众具备有重要意义的人防工程就不可不提,其存在是将深埋地下的空间与资源进行最大化发掘及利用,从而做到与其他国防工程组成部分契合,实现立体化国防工程的建设发展。人防工程虽然不显于人前,但其重要性却无人可以忽略,其对于城市建设发展、民众生命利益保障奠定着坚实基础。     

川西北高原藏区农村贫困化分异机制探测

[目的]客观揭示农村贫困化地域分异机制,为科学推进川西北高原藏区精准扶贫创新途径、综合战略和认真贯彻落实中央治藏方略提供参考依据。[方法]应用地理探测器模型、GIS空间分析与地统计方法等方法,探测川西北高原藏区贫困村单位面积GDP分异的主导因素,揭示农村贫困化分异机制,提出不同贫困化地域类型的扶贫政策措施。[结果]影响川西北高原藏区农村贫困化分异的主导因素包括到主要交通道路距离、归一化植被指数(NDVI)、土地利用、年均温度和海拔高程等,各因素对贫困村经济发展分异的解释力分别为80. 76%、12. 82%、8. 82%、5. 45%和3. 96%;贫困村经济发展贫困化的分异机制存在明显差异,可归纳为交通区位约束型、自然环境约束型和经济区位约束型等三大类型;农村贫困化驱动机制下的贫困村精准扶贫政策措施亟需因地制宜、科学推进、讲求实效,有序推进精准扶贫战略。[结论]精准扶贫应分类指导、重点突破,尤其加强贫困村交通、水利、公共基础设施建设和特色农牧业产业培植,注重多种扶贫模式的综合集成。     

A reduced PDE method for European option pricing under multi-scale,multi-factor stochastic volatility

The number of tailor-made hybrid structured products has risen more prominently to fit each investor’s preferences and requirements as they become more diversified. The structured products entail synthetic derivatives such as combinations of bonds and/or stocks conditional on how they are backed up by underlying securities, stochastic volatility, stochastic interest rates or exchanges rates. The complexity of these multi-asset structures yields lots of difficulties of pricing the products. Because of the complexity, Monte-Carlo simulation is a possible choice to price them but it may not produce stable Greeks leading to a trouble in hedging against risks. In this light, it is desirable to use partial differential equations with relevant analytic and numerical techniques. Even if the partial differential equation method would generate stable security prices and Greeks for single asset options, however, it may result in the curse of dimensionality when pricing multi-asset derivatives. In this study, we make the best use of multi-scale nature of stochastic volatility to lift the curse of dimensionality for up to three asset cases. Also, we present a transformation formula by which the pricing group parameters required for the multi-asset options in illiquid market can be calculated from the underlying market parameters.     

结构性减税与扩张政府支出的宏观经济效应

为了深入研究不同类型财政政策对宏观经济的影响效应，本文构建纳入异质性家庭和细化财税工具的新凯恩斯DSGE模型，并着重模拟分析了不同类型财政政策冲击对居民消费、私人投资、通胀率以及总产出水平的动态影响效应。研究结果表明，不同类型财税工具对宏观经济的冲击效果存在显著差异，对于税收政策，劳动收入税减税能够有助于提升消费水平和消费需求，并调节和完善消费结构；而对于政府支出政策，转移支付规模的扩张通过刺激家庭消费，引导消费内需有效提升，从而带动经济增长方式由投资驱动型向消费驱动型转变，进而推动经济高质量发展。     

"利剑斩污"行动下石家庄市挥发性有机物的污染特性变化研究

为研究石家庄市在"利剑斩污"行动管控期和非管控期挥发性有机物(VOCs)的污染特性变化,在2个时间段内对石家庄市3个国控点进行采样分析。通过苏玛罐(SUMMA罐)进行样品采集,利用气相色谱/质谱联用(GC/MS)仪对石家庄市区3个国控点的VOCs进行定性定量检测分析。结果表明,监测期间主要的特征污染物是二氯甲烷、二氯丙烷、苯和甲苯。与非管控期间相比,管控期间各污染物的质量浓度均有所降低,总VOCs平均质量浓度降低45.107μg/m~3,二氯甲烷质量浓度降低8.796μg/m~3,二氯丙烷质量浓度降低3.750μg/m~3,苯质量浓度降低18.285μg/m~3,甲苯质量浓度降低16.895μg/m~3。大气环境调控策略的实施,有效降低了VOCs浓度,减少了空气污染程度,空气质量改善效果显著。"利剑斩污"行动期间采取的相关举措,对于制定常态化下VOCs的防治对策具有一定的参考价值。     

碳排放交易制度的节能减排路径：效率提升还是结构转型？——来自中国省级数据的准自然实验

以中国2013年以来实行的碳排放交易试点政策作为准自然实验事件，基于2000-2017年中国30个省市的面板数据，运用双重差分法实证检验碳排放交易制度的节能减排效应及影响机制。研究发现，碳排放交易制度有利于实现中国经济“节能”与“减排”的双重目标，并通过了一系列稳健性检验；作用机制检验表明，能源效率提升和能源结构转型都是碳排放交易制度实现节能减排目标的重要路径；能源效率提升在碳排放交易制度实现“节能”和“减排”中分别发挥了10.19%和5.93%的作用，而能源结构转型分别发挥了48.87%和52.95%的作用。这意味着中国碳排放交易制度实现节能减排的主要动力来自能源结构转型，而非能源效率提升。能源结构转型涉及问题更加宏观和深层，这为中国加快推进节能减排进程，特别是完成2030年碳达峰和2060年碳中和的国际承诺提供政策启示。     

Comparison of dimension reduction methods for DEA under big data via Monte Carlo simulation

Data with large dimensions will bring various problems to the application of data envelopment analysis (DEA). In this study, we focus on a “big data” problem related to the considerably large dimensions of the input-output data. The four most widely used approaches to guide dimension reduction in DEA are compared via Monte Carlo simulation, including principal component analysis (PCA-DEA), which is based on the idea of aggregating input and output, efficiency contribution measurement (ECM), average efficiency measure (AEC), and regression-based detection (RB), which is based on the idea of variable selection. We compare the performance of these methods under different scenarios and a brand-new comparison benchmark for the simulation test. In addition, we discuss the effect of initial variable selection in RB for the first time. Based on the results, we offer guidelines that are more reliable on how to choose an appropriate method.