重量误差对隔振系统性能的影响

从如何确定航空电子设备配重模型件重量精度指标的角度,分析了重量误差对隔振系统性能的影响,提出了解决问题的观点和方法.     

基于熵权Topsis的淮河生态经济带水资源承载力评价

[目的]评价发展规划驱动下的水资源承载力特征,为区域发展提供科学依据。[方法]以淮河生态经济带为对象,采用熵权重的Topsis评价方法,分析淮河生态经济带水资源承载力的区域差异及其影响因素。[结果] 2015年不同市县水资源承载力综合得分介于0. 305 8～0. 698 8之间,其中盐城市最高,桐柏县最低;境内江苏、安徽、河南3省的水资源承载力分别为0. 585 2、0. 478 2、0. 524 9。[结论](1)淮河生态经济带水资源承载力具有在淮河干流上、下游承载力高,但中游偏低的空间分布特征。(2)水资源系统层面,水资源总量是承载力高低的供给侧决定性因素,是水资源承载力高低的重要基础。(3)社会系统中,用水量与用水结构是提升和优化水资源承载力的调控性因素。(4)城镇化发展与人口增加是水资源承载力高低的胁迫性因素,而经济发展水平是水资源承载力调控的重要保证。     

基于改进粒子群算法的无人机航迹规划

针对当前基本粒子群算法无人机航迹规划在后期收敛速度比较慢、效率不高、易陷入局部最优等问题,提出一种改进粒子群算法。首先,在迭代前期和后期分段设置惯性权值的调整,实现粒子惯性和寻优行为的平衡;其次,设置一个定值与相邻2次适应度函数最优值比较策略,防止陷入局部最优;最后,引入遗传算法的交叉、变异机制,得出更优的结果。并通过仿真验证了改进粒子群算法在三维空间航迹规划的有效性和可行性。结果表明,与其他航迹规划算法相比,新算法具有路径长度更短、耗时更少、路径更平滑等优点,加快了收敛速度,提高了航迹规划效率和稳定性。因此,改进算法的航迹规划可得到满足约束关系的最优航迹,对实现自主飞行有重要的参考价值。     

Threats to the Validity of Logistics and Supply Chain Management Research

To increase the relevance of logistics and supply chain academic research, this paper recommends the development and testing of middle‐range theory and practice‐level theory. Yet, there are a number of research issues that arise when academic researchers test middle‐range and practice‐level theory, both in measuring constructs and in testing theoretical relationships between constructs. Concerning the measurement of constructs, this paper recommends that academic researchers pay more attention to content validity and undertake rigorous processes to ensure content validity. In addition, academic researchers need to more explicitly define constructs as either reflective or formative. If the construct is defined as formative, then the traditional statistical approaches to validate these measurement scales are not recommended. The appropriate use of employing single‐item measures for concrete constructs is discussed. In regard to conducting hypothesis tests, research issues associated with multicollinearity and omitted variable bias are discussed. Relative weight analysis is ideal for testing theoretical models and research hypotheses when survey data are obtained, multicollinearity is present, and there are a large number of independent variables predicting a dependent variable. Thus, relative weight analysis is ideal for testing research hypotheses in logistics and supply chain management.     

粒子群算法惯性算子凹凸性分析

粒子群算法的惯性因子是算法中的一个重要的参数,目前的研究结果表明,惯性因子为减函数时算法的运行效果更为良好。文中提供了四种减函数作为惯性因子可以使用的算子,它们的凹凸性各有不同。对四个算例的数值仿真结果表明,表现最好的是惯性因子先上凸后下凸的PSO,惯性因子为下凸函数的PSO综合表现优于惯性因子为上凸函数的情况。     

黑龙江森工林区接替产业发展评价

运用熵权灰色关联分析法对黑龙江省森工林区所辖4个林业管理局2012—2017年养殖业、绿色食品等5个接替产业综合发展水平进行评价,并运用耦合协调度模型测算接替产业的均衡水平。结果表明:不同林业管理局的5个接替产业均呈波动发展状态;伊春林业管理局的优势接替产业是养殖业、绿色食品、北药开发和工业,牡丹江林业管理局的优势接替产业是绿色食品,合江林业管理局的优势接替产业是服务业,松花江林业管理局没有显著的优势接替产业;接替产业的综合发展水平偏低导致其均衡水平不高,总体上由初步协调向中度协调发展。因此,各林业管理局应继续发展具有优势的接替产业,同时扶持相对薄弱的接替产业,并开发与引进新的接替产业。     

Revisiting Attributes: How Important Is Green in the Consumer Selection of Hotel Rooms?

Consumers’ buying behavior is not always consistent with their positive attitude, particularly toward environmentally friendly products. In a survey of 197 travelers, the relative importance consumers ascribe to the attribute of green was assessed. Through a multi-methods study involving interviews, focus groups discussions, and forced-choice experiments that simulate market buying situation, it was found that consumers’ selection of hotel rooms is still much dictated by traditional choice factors. Through a conjoint analysis, it was found that consumers highly prioritized the price attribute. The green attribute was assigned a low relative importance of 4% among the respondents. Managerial and theoretical implications are discussed.     

基于组合赋权的青海省水资源承载力模糊物元分析

以青海省为研究区域,以其所辖的8个行政分区作为研究单元,利用基于组合赋权的模糊物元分析法,从用水总量、用水效率、水质3个维度建立青海省水资源承载力的"三条红线"评价指标体系。结果显示:青海省水资源还具有较大的开发潜力,水资源承载能力较强。但是青海省水资源开发利用条件和程度呈现出区域性差异,西宁市和海东市水资源承载力已近饱和状态,而其余地区水资源承载力相对较强,必须因地制宜采取相应的改善措施。     

House price determinants in Athens: a spatial econometric approach

In this paper, we try to identify the price determinants in the biggest real estate market of Greece, the metropolitan area of Athens. For that purpose, various spatial econometric models are used to explore their prediction ability and we are displaying the variations in property prices for the wider area of Athens. These models have been compared based on different criteria such as model fit, the Akaike information criterion and variance of the residuals. Our results indicate that, in our case, the spatial general model is the most appropriate simultaneous autoregressive model when dealing with spatially autocorrelated prices of housing properties data, in terms of our selection criteria.     

沈抚连接带“三生”空间的功能均衡性分析

随着人口增长和城市化发展,国土空间利用类型之间的竞争关系逐步增强,空间问题日益突显。自十八大报告明确提出"三生"空间以来,以生产、生活、生态划分的土地空间类型越来越被关注。该研究以沈抚连接带为研究区域,从土地空间的生产、生活和生态功能出发,构建"三生"功能评价指标体系。采用熵权法进行"三生"功能评价,利用GIS技术分析"三生"功能的空间格局。研究结果表明,"三生"功能均较强的街道具有较高的经济发展水平,如五三街道、李石街道,分值为64.96、54.59;生活功能较强的街道一般相邻城市,如五三街道、白塔街道、李石街道,分值为23.15、15.82、11.14,人均道路面积和公共服务设施完备度是主要影响因素;生态功能较高的街道多集中在浑河景观带和北部生态区,如高坎街道、满堂街道、东陵街道,分值为20.50、19.98、19.96,水面面积率、森林覆盖率和景观Shannon多样性是主要影响因素;生产功能较强的街道集中在建设快速区内,如李石街道、五三街道,分值为39.25、25.85,工业产值和服务业产值是主要影响因素。总体上看,受城市和经济建设活动影响强烈的街道的"三生"空间的功能不均衡性较为明显。