基于两次平衡计算的南昌市耕作层土壤剥离再利用空间配置研究

研究目的:探讨耕作层土壤剥离再利用空间配置思路与方法,并以南昌市为例进行实证研究,为相关工作提供借鉴。研究方法:提出基于线性规划及OD成本矩阵方法的两次平衡计算的耕作层土壤剥离再利用土方空间配置思路。首先,确定剥离、覆土优先度并结合供求关系划定供需圈,在供需圈内部进行第一次调配平衡;其次,对于内部不能平衡的供需圈,进行第二次跨圈调配平衡,达到缩短运输距离,控制成本目的。研究结果:(1)南昌市耕作层剥离量能够满足覆土数量与质量的需求;(2)空间配置结果共划定18个供需圈,供需圈内土方调配加权平均运输距离为6 682 m,小于期望值10 km,满足项目实施要求;(3)共有15个供需圈存在土方量不平衡问题,跨圈调配的距离平均为72 071 m,满足短距离运输的要求。研究结论:以耕作层土壤剥离、覆土优先度及供求关系为基础划定供需圈,基于线性规划及OD成本矩阵的两次平衡计算的空间配置思路与方法,可以优化运输距离,减少运输成本,提高项目实施效益。本文提出的空间配置思路可以为耕作层剥离再利用工程的顺利实施提供理论与方法借鉴。     

Limitations of portfolio diversification through fat tails of the return Distributions: Some empirical evidence

This study investigates the level of risk due to fat tails of the return distribution and the changes of tail fatness (TF) through portfolio diversification. TF is not eliminated through portfolio diversification, and, interestingly, the positive tail has declining fatness until a certain level is reached, while the negative tail has rising fatness. This indicates that fat tails are highly relevant to common factors on systematic risk and that the relevance of common factors is higher for the negative tail compared to the positive tail. In the portfolio diversification effect, the declining fatness of the positive tail further reduces risk, but the rising fatness of the negative tail does not contribute to this effect. The asymmetry between the fatness of the positive and negative tails in the return distribution corresponds to the asymmetry of the trade-off relationship between loss avoidance and profit sacrifice that is expected as a consequence of portfolio diversification. Investors use portfolio diversification to reduce their risk of suffering high losses, but following this strategy means sacrificing high-profit potential. Our study provides empirical confirmation for the practical limitation of portfolio diversification and explains why investors with diversified portfolios suffer high losses from market crashes. An examination of the Northeast Asian stock markets of China, Japan, Korea, and Taiwan show identical results.     

融合反距离加权和矩阵填充的位置指纹库构建

为解决位置指纹定位在离线阶段构建位置指纹库时耗费的人力和时间成本较大，构建指纹库效率低和利用空间插值法构建的指纹库精度不高的问题，提出了一种融合反距离加权和矩阵填充的位置指纹库构建算法。该算法仅需人工采集定位区域内少量参考点的接收信号强度值用作信标点指纹信息，结合反距离加权算法特性计算出次信标点指纹信息，根据位置指纹库数据矩阵的低秩性，应用奇异值阈值矩阵填充算法构建出位置指纹数据库。仿真实验结果表明，所提算法有效降低了矩阵填充算法构建位置指纹库所需的人工和时间成本，构建出的位置指纹库定位性能优于反距离加权和克里金空间插值法，接近传统人工采集法，显著地提高了位置指纹库的构建效率。     

双平行线阵的快速一维DOA估计

针对传统子空间算法需要进行特征值分解或奇异值分解等复杂计算的问题，提出一种双平行线阵（Double Parallel Linear Array,DPLA）的快速一维波达方向（Direction of Arrival，DOA）估计算法。算法通过处理互协方差矩阵的第一列元素构造出等效的噪声子空间，再通过求根MUSIC（Multiple Signal Classification）算法得到DOA估计，有效避开了特征值分解或奇异值分解，降低了计算复杂度，提高了运算速度。仿真结果表明，该算法在提高了估计精度的同时减少了估计时间。     

Farmers’ attitude towards the policy of remediation during fallow in soil fertility declining and heavy metal polluted area of China

Numerous countries and regions face soil fertility decline and heavy metal pollution, and China implements a policy of remediation during fallow (PRF) to deal with such challenges. In this study, we examine the evolution of PRF and surveys of farmers’ attitudes in China. We present suggestions which can be used as reference for other countries and regions. The Chinese government implemented the policy of remediation during production (PRP) to control the heavy metal pollution of land in 2014. The effect was unsatisfactory due to the lack of cooperation amongst farmers. Therefore, the Chinese government implemented PRF in 2016. Our investigation of 247 farmers shows that farmers’ comprehensive assessment of PRF is positively influenced by the cognition of government implementation, the cognition of policy function and the evaluation of value perception, and the PRF still faces several problems, such as low cognitive level of policy function, incomplete regulations of supervision and poor supporting system. Hence, we suggest that government should educate and train farmers, improve the supervision and set up the supporting system of PRF.     

一种改进的非凸秩最小化算法及其在矩阵恢复中的应用

在分析现有处理矩阵恢复问题的非凸秩最小化算法的基础上,提出了一种基于超松弛迭代的改进算法,并给出了松弛因子ω的确定准则。仿真实验表明:在惩罚参数选取较大的情形下,改进算法较原算法具有更快的收敛速度及更高的收敛精度,同时展示了基于非凸秩最小化算法的矩阵恢复技术在图像去噪中的应用。     

Multiple Levels of Corporate Sustainability

According to Dr. Clare Graves, mankind has developed eight core value systems,1 as responses to prevailing circumstances. Given different contexts and value systems, a one-solution-fits-all concept of corporate sustainability is not reasonable. Therefore, this paper presents various definitions and forms of sustainability, each linked to specific (societal) circumstances and related value systems. A sustainability matrix– an essential element of the overall European Corporate Sustainability Framework – is described showing six types of organizations at different developmental stages, with different forms of corporate sustainability, each supported by specific institutional arrangements.     

现代汽车涂装防腐技术的应用与发展

综述汽车的金属腐蚀及危害,引起汽车金属腐蚀的主要因素,着重从结构设计、材料应用和防护工艺等方面介绍现代汽车的金属防腐技术,并提出汽车应用金属防腐技术的发展方向.     

一个与供应链协同的虚拟价值网集成增值矩阵

运用集成原理及系统方法论探讨了虚拟价值网集成的结构机理,从集成意义上构造了一个与供应链协同的增值矩阵,即基于信息共享、知识共享、价值共享的三个平台,虚拟实现与工作流、知识流、价值流协同的供应链上的信息流、财务流和物流增值。同时作出虚拟价值网集成管理的优化树图,为现行供应链管理模式的优化升级提供模拟支持和方法选择。     

虚拟企业的组织本质解释

虚拟企业作为一种新型的组织形式 ,目前 ,国内外许多的经济学家、管理学家已对其进行了多方面的研究 ,如虚拟企业的产生、定义、特点、优势等 ,但是 ,并未曾涉及虚拟企业的组织本质。采用“交易费用”理论来解释虚拟企业的产生、存在的原因 ,进而揭露其组织本质———企业间的矩阵结构。