河北保定农户居住空间行为选择的动力机制研究

农户对居住空间的行为选择是直接影响乡村空间秩序的重要因素,只有充分认识并准确把握其空间行为选择的现状及存在问题,才能从行为主体空间行为选择上进一步探寻合理引导其空间行为演变的发展道路。为了探讨当前新型城镇化背景下农户居住空间行为的演变规律,研究基于微观视角对保定市不同地区的农户进行了居住空间行为的问卷调查,并对结果进行了统计分析和结构方程模型的构建与检验。实证结果表明:(1)调查区域大部分农户对当前居住空间的满意程度为一般;(2)在农户居住空间满意度方面,配套环境驱动占主要地位,其路径系数高于住房条件驱动;(3)在配套环境驱动方面,经济活动交易便利是最主要因素;在经济生产条件驱动方面,耕种便利因子的影响程度高于灌溉条件。在住房条件驱动方面,各具体测度变量根据影响的主次程度排序依次为:建筑面积、宅基地面积、房屋结构、排水便利、出路与交通。建议保定市从配套设施建设、循序渐进的规范化引导、创新制度体系建设等方面合理引导农户居住空间的行为演变。     

Evaluating the impact of rising fertilizer prices on crop yields

Because of tensions on fossil energy and phosphorus markets, the rise in fertilizer prices observed during the last decades may continue in the future, putting into question production pathways relying heavily on crop intensification. To evaluate how, in this context, economic choices may alter crop yields, we first construct different fertilizer price scenarios to 2050 based on an econometric relation with oil and gas prices. Other possible scenarios, such as the continuation of historical trends, are also considered. The resulting changes in fertilizer price range between +0.8% and +3.6% per year over the 2005–2050 period. These scenarios are tested in a global land‐use model incorporating an endogenous representation of the land–fertilizer substitution. We find that the supply‐side response to rising fertilizer prices could lower crop yields in 2050 from ?6% to ?13%, with a corresponding increase in global cropland area ranging between 100 and 240 Mha if the demand for food and nonfood products has to be met. The sensitivity of these results is tested with regard to assumptions on food consumption, change in potential yield and nutrient use efficiency.     

Estimating firm-level and country-level effects in cross-sectional analyses: An application of hierarchical modeling in corporate disclosure studies

Researchers in the field of international accounting are often confronted with observations of firms clustered into higher-level units such as countries. Using data from a corporate disclosure study including 797 firm observations from 34 countries, we demonstrate that the inferences obtained from the most commonly used Ordinary Least Square (OLS) test, which pools the firm and country data either under the disaggregation or aggregation approach, are problematic and misleading. To overcome the methodological limitation, we subsequently employ hierarchical modeling to simultaneously estimate both firm-level (within-country) and country-level (cross-country) disclosure determinants. We find that the clustering effects are significant in almost all firm-level variables. Once such effects are adjusted, only three firm-specific variables are significantly associated with corporate disclosure. Evidence provided by this study has important implications for most international accounting studies conducted in cross-level contexts.     

需求不确定下的供应链协调建模

采用由整体到局部的研究思路,首先就目前学术界对供应链协调的整体研究情况进行概述,在此基础上进行了延伸;将主要研究方向着眼于需求不确定下的供应链协调方法的研究;最后,通过理论分析与模型构建相结合的研究方法,得到一个针对单个销售商和单个供应商的基于需求不确定条件下的供应链协调模型,提出了未来研究展望。     

生别调解下高卷入产品品牌体验对品牌忠诚的影响

顾客的品牌体验会影响品牌忠诚,在现有文献中已基本达成其识。本文基于进一步的维度划分,研究了品牌体验五个维度对品牌忠诚两个维度的不同影响,尤其检验了性别差异的调解作用。构建了以品牌体验为自变量,品牌忠诚为因变量,性别为调节变量的结构方程模型,进行实证研究。结果表明：品牌体验各维度对品牌忠诚的影响有不同,并且性别差异的调解效应显著。并提出企业应根据不同的目标顾客群,以不同的体验维度为重点构建品牌忠诚。从一个新的视角为品牌忠诚构建提供了理论指导。     

虚拟场景建模技术研究

虚拟现实技术是用现代计算机技术创建的一种酷似客观环境又超越客观时空的和谐人机环境,它是现代仿真领域的一个重要发展方向。虚拟现实技术中的虚拟场景建模工作是研究的核心问题。目前解决这个问题主要基于几何造型的建模和基于图像的建模两种方法。本文研究了虚拟现实技术的特点及其存在问题,围绕当今热的虚拟场景建模技术进行了深入探讨,详细分析比较了现今两种虚拟场景的构建技术。     

数学建模与创新应用型人才培养

培养具有创新精神的应用型人才已经成为很多大学的办学目标,数学建模正是培养学生创新精神与实践能力的有效方法。     

Living with the Curse of Dimensionality: Closed-Loop Optimization in a Large-Scale Fisheries Simulation Model

Facilitated by remarkable increases in computational speed, simulation models are becoming more and more complex and are being increasingly used in applied economic analysis. However, computational limitations remain a major barrier to the study of dynamically optimal policies. We study the problem of carrying out dynamic optimization in conjunction with large simulation models and propose a method for working around the computational difficulties that arise in such problems. Our methods are applied to a model of the Gulf of Mexico's red snapper fishery to study the dynamically optimal total allowable catch.     

Knowledge relatedness and the performance of multibusiness firms

This study examines corporate performance effects of cross‐business knowledge synergies in multibusiness firms. It synthesizes the resource‐based view of diversification and the economic theory of complementarities to conceptualize cross‐business knowledge synergies in terms of the relatedness and the complementarity of knowledge resources across business units of the multibusiness firm. The study hypothesizes that corporate performance is improved when the firm simultaneously exploits a complementary set of related knowledge resources across its business units. In a sample of 303 multibusiness firms, the study finds that synergies arising from product knowledge relatedness, customer knowledge relatedness, or managerial knowledge relatedness do not improve corporate performance on their own. Synergies arising from the complementarity of the three types of knowledge relatedness significantly improve both market‐based and accounting‐based performance of the multibusiness corporation. Copyright © 2004 John Wiley & Sons, Ltd.     

激光仿型快速测量系统的设计开发

文章介绍了应用激光仿型开发快速测量系统的设计过程及其相关的关键技术,并就该技术中的难点进行了引导性分析