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1.
随着植物园"旅游经济"的发展,植物园在承担植物科学研究及科普功能的同时,也成为公众日常休闲的重要绿地。本文选取南京中山植物园作为研究对象,建立评价体系并运用模糊综合评价法对游客满意度进行研究,探寻影响植物园游憩功能的显著因子,为未来植物园规划设计提供参考。结果表明:游客对南京中山植物园的游憩功能达到基本满意水平。其中,植物物种多样性、景区分布、建筑景观、声景观的满意度较高,滨水景观的满意度评价值较低。通过Pearson相关系数发现植物色彩丰富度、科普场所、科普内容是影响游客满意度的显著因子。运用IPA图对16项评价因子进行重要度-满意度分析,并对各象限内的因子提出改进方向。最后基于游憩功能满意度评价结果,提出改进策略:加大对植物园休息设施、卫生设施、娱乐设施和商业服务设施的投入;更新科普方式,增添特色游憩主题园区;完善现有道路体系,增强对北部专类园的可达性;增加色叶植物的种类、提高色彩丰富度等。以期为中山植物园游憩功能的优化及其他植物园的规划设计提供借鉴。  相似文献   
2.
随着信息技术的发展,数字经济已经成为经济增长的"新引擎"。但由于缺乏权威的产业统计分类标准,学者们一直面临"数字经济研究缺乏数字依据"的尴尬境地。文章基于国家统计局公布并实施的《数字经济及其核心产业统计分类(2021)》中的分类标准,对各省份统计年鉴的数据进行重新整理,利用熵权法构建数字经济发展指数,测度了我国30个省份的数字经济发展水平,分析了各省份数字经济发展的差异以及时空特征。研究发现,2009—2019年我国数字经济产业发展迅猛,各项子产业都取得了长足的进步。相比较而言,数字要素驱动业发展速度略低于其他三个子产业;数字经济发展存在着明显的区域不平衡。东中部地区的数字经济发展状况明显优于西部地区,南方优于北方,而且区域不平衡有持续扩大趋势。  相似文献   
3.
This paper proposes a new hysteretic vector autoregressive (HVAR) model in which the regime switching may be delayed when the hysteresis variable lies in a hysteresis zone. We integrate an adapted multivariate Student-t distribution from amending the scale mixtures of normal distributions. This HVAR model allows for a higher degree of flexibility in the degrees of freedom for each time series. We use the proposed model to test for a causal relationship between any two target time series. Using posterior odds ratios, we overcome the limitations of the classical approach to multiple testing. Both simulated and real examples herein help illustrate the suggested methods. We apply the proposed HVAR model to investigate the causal relationship between the quarterly growth rates of gross domestic product of United Kingdom and United States. Moreover, we check the pairwise lagged dependence of daily PM2.5 levels in three districts of Taipei.  相似文献   
4.
Assessment of analytical similarity of tier 1 quality attributes is based on a set of hypotheses that tests the mean difference of reference and test products against a margin adjusted for standard deviation of the reference product. Thus, proper assessment of the biosimilarity hypothesis requires statistical tests that account for the uncertainty associated with the estimations of the mean differences and the standard deviation of the reference product. Recently, a linear reformulation of the biosimilarity hypothesis has been proposed, which facilitates development and implementation of statistical tests. These statistical tests account for the uncertainty in the estimation process of all the unknown parameters. In this paper, we survey methods for constructing confidence intervals for testing the linearized reformulation of the biosimilarity hypothesis and also compare the performance of the methods. We discuss test procedures using confidence intervals to make possible comparison among recently developed methods as well as other previously developed methods that have not been applied for demonstrating analytical similarity. A computer simulation study was conducted to compare the performance of the methods based on the ability to maintain the test size and power, as well as computational complexity. We demonstrate the methods using two example applications. At the end, we make recommendations concerning the use of the methods.  相似文献   
5.
针对跨国供应商选择与订单分配问题,在考虑进口配额限制和需求不确定的情境下,构建了一个实现核心制造商利润最大化和供应商交货质量最大化的模糊多目标混合整数规划模型。该模型考虑汇率、关税等多个全球因素,采用一种交互式模糊多目标规划方法对模型进行求解,并应用一个算例进行验证。研究表明:1.存在进口配额限制时,制造商会优先考虑低成本高质量的海外供应商,达到配额限制后再选择本土供应商补充剩余订单;2.人民币汇率正向影响制造商海外采购。当人民币汇率上升时,制造商进口成本降低,其会将更多订单分配给海外供应商;3.关税负向影响制造商海外采购。当关税上升时,制造商会减少关税高的供应商的进口数量,选择替代供应商来满足其需求。由此获得如下管理启示:1,制造商企业在选择跨国供应商时,应重点关注本国的进口配额政策,使供应商多样化以减少针对单一供应商配额政策剧烈波动对制造商采购成本和企业利润的不利影响。2.汇率时刻都在变动,制造商企业应关注本国和供应商所在国的长期汇率政策以及短期突发事件对汇率的影响,及时调整订单分配决策。3.制造商企业在选择供应商时,需要对供应商所在国的短期和中长期关税政策进行综合评估。  相似文献   
6.
In 2015, the United Nations (UN) issued probabilistic population projections for all countries up to 2100, by simulating future levels of total fertility and life expectancy and combining the results using a standard cohort component projection method. For the 40 countries with generalized HIV/AIDS epidemics, the mortality projections used the Spectrum/Estimation and Projection Package (EPP) model, a complex, multistate model designed for short-term projections of policy-relevant quantities for the epidemic. We propose a simpler approach that is more compatible with existing UN projection methods for other countries. Changes in life expectancy are projected probabilistically using a simple time series regression and then converted to age- and sex-specific mortality rates using model life tables designed for countries with HIV/AIDS epidemics. These are then input to the cohort component method, as for other countries. The method performed well in an out-of-sample cross-validation experiment. It gives similar short-run projections to Spectrum/EPP, while being simpler and avoiding multistate modelling.  相似文献   
7.
为了对多个多属性(指标)待评价对象(方案)在多个时间点的发展状态和该时间段内的总体发展水平进行比较分析,根据理想解法和灰关联度法优缺点,提出基于理想解和灰关联度的动态评价方法。该方法基于三维数据,将欧氏距离和灰色关联度相结合,提出一种新贴近度,同时反映了位置关系和数据曲线的相似性差异,兼顾评价指标值差异程度和增长程度。最后将该方法应用于"十二五"期间省域循环经济生态效益评价,通过实例验证该方法实际应用上的有效性。  相似文献   
8.
Abstract

The purpose of this study is to investigate the influence of sustainable supply chain management (SSCM) practices on triple bottom line (TBL) measures from the perspective of organizational theories. This study identified five SSCM practices using a comprehensive literature review and feedback from industry experts. These five practices were prioritized using a fuzzy analytical hierarchy process (FAHP). The results from FAHP analysis were further confirmed by conducting semi-structured interviews in five electronics parts/components manufacturing organizations. This study also prioritized theoretical drivers of SSCM adoption based on the consideration of three organizational theory perspectives – Institutional Theory; Resource-Based View, and; Social Network Theory. The results indicate that the economic dimension was the most important measure for implementing SSCM while sustainable design was the most important SSCM practice for achieving the TBL. The study also found that Institutional Theory is the most important theoretical driver for implementing SSCM. The research findings provide insight for management to allocate necessary resources and to develop effective strategic directions for the implementation of SSCM practices.  相似文献   
9.
This scoping review of 62 knowledge syntheses published in evaluation-focused journals between 1979 and May 2018 provides a portrait of synthesis practices and their evolution in the mainstream of the field of evaluation. Concerns surrounding the production of knowledge syntheses to answer policy questions are not new in the field of evaluation. However, during this last decade, knowledge synthesis methods have expanded as a means to go beyond the limits and constraints of singular evaluations. This scoping review reveals and discusses two key issues with regards to the expansion of knowledge synthesis practices within the field of evaluation: the diversity—and muddling— of methodological practices and synthesis designs, and the frequent omission of quality appraisals.  相似文献   
10.
We consider importance sampling (IS) type weighted estimators based on Markov chain Monte Carlo (MCMC) targeting an approximate marginal of the target distribution. In the context of Bayesian latent variable models, the MCMC typically operates on the hyperparameters, and the subsequent weighting may be based on IS or sequential Monte Carlo (SMC), but allows for multilevel techniques as well. The IS approach provides a natural alternative to delayed acceptance (DA) pseudo-marginal/particle MCMC, and has many advantages over DA, including a straightforward parallelization and additional flexibility in MCMC implementation. We detail minimal conditions which ensure strong consistency of the suggested estimators, and provide central limit theorems with expressions for asymptotic variances. We demonstrate how our method can make use of SMC in the state space models context, using Laplace approximations and time-discretized diffusions. Our experimental results are promising and show that the IS-type approach can provide substantial gains relative to an analogous DA scheme, and is often competitive even without parallelization.  相似文献   
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