Almost Stochastic Dominance and Efficient Investment Sets

A major drawback of Mean-Variance and Stochastic Dominance investment criteria is that they may fail to determine dominance even in situations when all “reasonable” decision-makers would clearly prefer one alternative over another. Leshno and Levy [1] suggest Almost Stochastic Dominance (ASD) as a remedy. This paper develops algorithms for deriving the ASD efficient sets. Empirical application reveals that the improvement to the efficient sets implied by ASD is substantial (64% reduction for FSD). Direct expected utility maximization shows that investment portfolios excluded from the ASD efficient set would not have been chosen by any investors with reasonable preferences.

基于InVEST模型的河南省农田氮素面源污染时空模拟

【目的】进行农田氮素面源污染模拟,分析其时空分布特征及影响因素,实现高效治理面源污染和农业生态保护。【方法】综合农业分区、地形、种植模式、熟制、土地覆被等因素,划分河南省土地利用类型单元,基于InVEST模型对2000、2010和2020年河南省农田氮素面源污染状况进行时空模拟,并对输出负荷和影响因素进行分析。【结果】河南省大部分地市的氮素输出负荷总量及氮素排放强度与总体变化趋势相同,都呈现“先增后减”的趋势。各地市间差异明显,高氮素排放强度地区为南阳、信阳和驻马店市。氮素输出强度与地均施氮肥量、数字地理高程模型(digital elevation model,DEM)、降雨量、农田比例和坡度5个因素间均存在显著相关关系。偏相关分析表明,氮素输出强度与地均施氮肥量和降雨量密切相关。氮素排放强度分级结果表明,南阳、信阳和驻马店市存在一定范围的中高强度的排放区。【结论】揭示了河南省农田面源污染高排放强度区及其重要影响因素,从而促进相关氮素面源污染防控和精确治理。

Heteroatom substitution-induced asymmetric A–D–A type non-fullerene acceptor for efficient organic solar cells

Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart.In this contribution,by simply replacing one sulfur atom in indacenodithiophene unit with a selenium atom,an asymmetric building block Se PT and a corresponding asymmetric non-fullerene acceptor Se PT-IN have been developed.Asymmetric Se PT-IN achieved a high efficiency of 10.20% in organic solar cells when blended with PBT1-C,much higher than that of symmetric TPT-IN counterpart(8.91%).Our results demonstrated an effective heteroatom substitution strategy to develop asymmetric A–D–A structured non-fullerene acceptors.

Evaluate the Investment Efficiency by Using Data Envelopment Analysis: The Case of China

Although investment is regarded as a key force of China’s economic growth, little study has been done to measure China’s investment efficiency. The present paper applies the data envelopment analysis (DEA) to Chinese provincial panel data from the year 2003 to 2008 for measuring the investment efficiencies and identifying their trends of Chinese 30 provinces and autonomous regions. A cross-efficient DEA model with considering benevolent formulation is used for providing accurate efficiency scores and completely ranking. The empirical results suggest that the differences of investment efficiency in different regions are distinct but tending to diminish year by year, and the investment efficiencies in some provinces are significantly correlated to their investment rates to the national total investment.

Research on the Relationship Between Financial Redundancy, Financing Constraints and Investment Efficiency in Manufacturing Listed Companies

Investment helps companies achieve innovation. Efficient investments often do more with less. Manufacturing enterprises should pay more attention to the issue of investment efficiency, seize investment opportunities and achieve efficient investment. Due to the continuous increase of borrowing costs in the financial markets, enterprises are getting more and more difficult to raise funds from the outside, so more and more enterprises are turning their attention to the financially redundant resources within the enterprises. Making good use of financially redundant resources will help enterprises solve the financing difficulties and enable them to have sufficient funds for investment activities and lay the foundation for sustainable development.

A Higher-Efficient Non-Hydrostatic Finite Volume Model for Strong Three-Dimensional Free Surface Flows and Sediment Transport

In order to accurately simulate strong three-dimensional （3-D） free surface flows and sediment transport, the fully 3- D non-hydrostatic pressure models are developed based on the incompressible Navier-Stokes equations and convection-diffusion equation of sediment concentration with the mixing triangle and quadrilateral grids. The governing equations are discretized with the unstructured finite volume method in order to provide conservation properties of mass and momentum, and flexibility with practical application. It is shown that it is first-order accurate on nonuniform plane two-dimensional （2-D） grids and second-order accurate on uniform plane grids. A third-order approximation of the vertical velocity at the top-layer is applied. In such a way, free surface zero stress boundary condition is satisfied maturely, and very few vertical layers are needed to give an accurate solution even for complex discontinuous flow and short wave simulation. The model is applied to four examples to simulate strong 3-D free surface flows and sediment transport where non-hydrostatic pressures have a considerable effect on the velocity field. The newly developed model is verified against analytical solutions with an excellent agreement.

Earnings information quality, debt maturity structure and investment efficiency

This paper studies the effect of earnings information quality and debt maturity structure and their interaction on investment efficiency. The results show that companies with higher earnings information have higher investment efficiency, and the quality of earnings information has increased investment efficiency by reducing the lack of investment and suppressing overinvestment. The companies with higher short-term debt ratio show higher investment efficiency. The results show that there is a certain substitution effect between the effect of earnings information quality and the maturity strueture of debt on the efficiency of investment.

Compliance management and investment efficiency in state-owned enterprises:Evidence from China

Drawing on the implementation of the compliance management guidelines issued by China’s SASACs,we construct a quasi-natural experiment to examine the impact of the implementation of these guidelines on the investment efficiency of SOEs.The investment efficiency of SOEs is significantly improved after the implementation of the guidelines.The impact is more pronounced on SOEs with significant financing constraints,high financing requirements and intense competition in the product market.We also find that the guidelines improve efficiency investment by reducing management’s risk appetite,mitigating the Type I agency problems and enhancing the level of internal control.The conclusions indicate that compliance management is an important strategy for enhancing the investment efficiency of SOEs.

Effects of Non-flooded Cultivation with Straw Mulching on Rice Agronomic Traits and Water Use Efficiency

A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated in flooded soil and non-flooded soils with and without straw mulching. The total amount of water used by rice under flooded cultivation （FC） was 2.42 and 3.31 times as much as that by rice under the non-flooded cultivation with and without straw mulching, respectively. The average water seepage was 13 560 m^3/ha under the flooded cultivation, 4 750 m^3/ha under the non-flooded cultivation without straw mulching （ZM） and 4 680 m^3/ha under non-flooded cultivation with straw mulching （SM）. The evapotranspiration in the SM treatment was only 38.2% and 63.6% of the FC treatment and ZM treatment, respectively. Compared with the ZM treatment, straw mulching significantly increased leaf area per plant, main root length, gross root length and root dry weight per plant of rice. The highest grain yield under the SM treatment （6 747 kg/ha） was close to the rice cultivated in flooded soil （6 811.5 kg / ha）. However, the yield under the ZM treatment （4 716 kg/ha） was much lower than that under the FS treatment and SM treatment. The order of water use efficiency and irrigation water use efficiency were both as follows： SM〉 ZM〉 FC.

Efficiency of Removing Sulfur Dioxide in the Air by Non-Thermal Plasma Along with the Application of the Magnetic Field

The non-thermal plasma created by high voltage pulsed power supply can be used to remove sulfur dioxide in the air, but how to increase the removing efficiency is not clear. It is novel to apply the magnetic field in removing SO2 as discussed in this paper. The mechanisms of removing sulfur dioxide by non-thermal plasma along with the application of the magnetic field are analyzed, and the related factors affecting the removal efficiency, such as the magnitude of pulsed voltage, the polarity of the pulse, the layout of the discharge electrode, especially the magnetic field are experimentally investigated. It can be concluded that the purification efficiency is improved significantly by applying the magnetic field.

Public and Private Investment in the Port Sector in Mexico, 2000-2010： A Study Through Data Envelopment Analysis

Knowing the level of efficiency of investment applied in ports of Mexico is relevant information for the design of port policies that contribute to its development and thus to greater freight movement. The objective of this paper is to analyze the technical efficiency obtained from International Mexican Ports, through the use of the technique of Data Envelopment Analysis （DEA）. It uses data regarding public and private investment in ports applied during the period 2000-2010 and its influence on the number of Twenty-foot Equivalent Unit （TEU）. Because it has been applied the DEA-CCR （the linear programming model） model input oriented, thus not only the efficiency is calculated in ports, but benchmarking is also obtained to determine the efficient ports that serve as reference to those who were found to be inefficient. The results obtained showed that Manzanillo and Progreso were the most efficient ports. On the other hand, the ports that were not efficient for any of the years reviewed were Mazatlan and Lazaro Cardenas. Generally, public investment has been increasing over the period, and public policies are not designed to allow the ports to have an international projection.

The Efficient Market Theory and Mergers and Acquisitions （M＆As） Puzzle： Evidence From Italy

The efficient market theory is a central point in finance. If the capital market is competitive, the investors cannot expect superior gains from their investment strategies with respect to the risk profile. Event studies are an approach to verify the impact of the information on the stock prices. In an efficient market, stock prices should fully, promptly, and quickly capture all the information. Instead, the market shows phenomena of an under-reaction and over-reaction for both the short and the long run. The mergers and acquisitions （M＆As） are examples of anomalies. Often, the bidder companies record the negative abnormal returns for both the short and the long run. In contrast to the efficient market theory, the empirical evidence shows that this phenomenon is widespread in all （or most of） the countries of the world. This work examines the long-run performance in M＆As. For this purpose, 40 bidders were observed in Italy during the period of 1994-2008 among listed companies. The buy and hold abnormal returns （BHARs） methodology was used, with which it was possible to observe the returns for three years following the deal.

Exploiting Spectral-Energy Efficiency Tradeoff with Fairness in Non-Orthogonal Multiple Access Systems

The spectral efficiency(SE)and energy efficiency(EE)tradeoff while ensuring rate fairness among users in non-orthogonal multiple access(NOMA)systems is investigated.In order to characterize the SE-EE tradeoff with rate fairness,a multi-objective optimization(MOO)problem is first formulated,where the rate fairness is represented with theα-fair utility function.Then,the MOO problem is converted into a single-objective optimization(SOO)problem by the weighted sum method.To solve the converted non-convex SOO problem,we apply sequential convex programming,which helps to propose a general power allocation algorithm to realize the SE-EE tradeoff with rate fairness.We prove the convergence of the proposed algorithm and the convergent solution satisfies the KKT conditions.Simulation results demonstrate the proposed power allocation algorithm can achieve various levels of rate fairness,and higher fairness results in degraded performance of SE-EE tradeoff.A pivotal conclusion is reached that NOMA systems significantly outperform orthogonal multiple access systems in terms of SE-EE tradeoff with the same level of rate fairness.

Study on Comprehensive Efficiency Evaluation of Rural Power Grid under Rural Revitalization Strategy Considering Regional Differences

As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its comprehensive efficiency.Based on the requirements of“double carbon”and rural revitalization strategy for the rural Power Grid,this paper focuses on the modernization and low-carbon transformation of the rural Power Grid.It constructs an input-output index system for the investment efficiency of the rural Power Grid in China under the new situation.It uses the primary data of the rural Power Grid of 30 prefecture-level cities in China from 2019 to 2021 to evaluate the investment efficiency of the rural Power Grid in China through a three-stage DEA model.The empirical results show that:considering the regional differences,the comprehensive efficiency of the rural Power Grid in backward areas is significantly improved;that is,the three-stage DEA method can more objectively evaluate the comprehensive efficiency of the rural Power Grid.In the context of the continued promotion of the rural revitalization strategy,to improve the comprehensive efficiency of the rural Power Grid,it is necessary to improve the technical level of the rural Power Grid further and appropriately expand the scale of investment in the rural Power Grid.

A Higher-Efficient Three-Dimensional Numerical Model for Small Amplitude Free Surface Flows

A higher-efficient three-dimensional non-hydrostatic model is developed to simulate small amplitude free surface flows based on a staggered unstructured grid. In this model, a fractional step algorithm is adopted to solve the Navier-Stokes equations in two major steps. A top-layer pressure method is proposed to minimize the number of vertical layers and subsequently the computational cost. Three classical examples of small amplitude free surface flows are used to demonstrate the capability and efficiency of the model. The satisfactory results demonstrated the capability and efficiency of modelling a range of small amplitude free surface flows with only a small number of vertical layers.

政府扶持能改善企业投资效率吗?——基于政府采购的经验证据

政府采购作为政府在需求端的市场化扶持手段引起了学界广泛关注。本文以2015—2020年沪深A股上市公司为研究对象,实证检验了政府采购对企业投资效率的影响。研究发现,政府采购能够提高企业投资效率,且能够同时抑制企业过度投资和投资不足;区分订单特征发现,仅异地政府采购能提高企业投资效率。机制检验表明,政府采购能够通过降低企业经营不确定性和信息不对称程度提高企业投资效率,且上述作用在产品市场竞争更为激烈的企业、处于政府审计监督力度较强地区的企业、非国有企业以及处于法治环境较差地区的企业中更加显著。本文的研究结论不仅为如何通过政府扶持提高企业投资效率提供了经验证据,也对如何积极开展政企互动和促进经济高质量发展具有重要启示。

企业财务柔性对创新绩效的影响——基于非效率投资中介作用的思考

以2016—2020年我国沪深两市高技术上市公司数据为研究样本,运用实证分析的方法,探究在非效率投资的中介作用下,企业财务柔性对创新绩效的影响。实证研究表明:财务柔性可以缓解企业的投资不足行为,适当储备财务柔性对提高企业创新绩效有促进作用;而过度的财务柔性会加剧过度投资行为,进而引发非效率投资问题。非效率投资会降低创新绩效,非效率投资在财务柔性与创新绩效间起中介作用。适当储备财务柔性对于减少非效率投资,提高企业创新绩效有积极作用。

高质量发展驱动下造纸企业环保投资效率的案例研究

我国经济高质量发展目标要求企业在实现经济价值的同时兼顾环境和社会效益。文章选取造纸业中环保数据披露较为全面、详细的景兴纸业作为案例研究对象。在前期学者等构建的环保投资效率评价指标体系的基础上,从经济、环境、社会三个维度构建了适合该企业的环保投资效率评价指标。从投入产出视角出发,运用DEA法对其环保投资效率进行评价,探寻其环保投资效率存在的问题及成因,并有针对性地提出相关对策建议,以期为高质量发展驱动下造纸业的环保投资决策提供参考和借鉴。

软枣猕猴桃“奇异莓6号”无芽茎段离体再生技术研究

取无芽茎段为外植体进行离体培养,具有成本低、取材方便、材料充足等优点。为克服软枣猕猴桃无芽茎段诱导再生率低的问题,以“奇异莓6号”软枣猕猴桃无菌苗无芽茎段为外植体,探究了不同植物生长调节剂、光照强度、温度、苗龄对不定芽诱导的影响,以及不同浓度IBA对生根的影响。结果表明,最佳外植体为苗龄30 d的无芽茎段,在光照12 h/d、光照强度50 lx、20℃下不定芽诱导的最适培养基为MS+2 mg/L ZT,不定芽以间接途径发生,培养40 d无芽茎段两端开始形成淡绿色愈伤组织,培养45 d愈伤组织表面出现红色小点,开始形成不定芽,培养55 d愈伤组织诱导率、愈伤组织分化率及不定芽数均到最大,分别为100%、100%及18.87个/块。待苗长至3 cm左右时转到MS+0.4 mg/L IBA中进行生根培养,培养30 d生根率可达100%,平均根数为8.53条/株,根长1.68 cm,根粗0.14 cm。