基于数字图像处理技术的再生混凝土数值模拟

为了研究骨料形态对再生混凝土材料力学性能的影响,基于势能原理的基面力元法,利用图像处理技术和MATLAB软件,建立了再生混凝土真实骨料细观模型。应用FORTRAN分析软件对再生混凝土试件进行单轴拉伸试验的数值模拟,研究了真实骨料细观模型再生混凝土宏观应力-应变曲线变化规律和试件的破坏形态。结果显示,真实骨料模型得到的宏观应力-应变曲线和试验曲线吻合度较高,骨料形状对试件的破坏形态影响较小。模型可真实地模拟再生混凝土在单轴拉伸作用下的损伤破坏过程,准确地反映试件的实际骨料形态。     

(In)equality and the South African Constitution

ABSTRACT

Does the South African Constitution constrain or empower government, courts and citizens in addressing systemic social and economic inequalities? This article argues that the Constitution is explicitly ‘transformative’, but is an enabling document, providing ‘scaffolding’ for political and legal activities. It is government, strong institutions and civil society that are ultimately responsible for securing its equality aspirations. Here the Constitution admits of different understandings of equality and different economic and social policy choices. This article identifies these contested meanings of equality and suggests that a liberal egalitarian/social democratic version is dominant in policy choices and the jurisprudence of the Constitutional Court. It illustrates this with reference to the Court’s jurisprudence on equality, and suggests that more radical and transformative interpretations remain possible. However, it concludes that we cannot escape politics, the need for good policy choices and effective implementation and enforcement.     

Consequences of a green image of drone food delivery services: The moderating role of gender and age

Drone food delivery services play a significant role in protecting the environment, because the services are operated by batteries that can be charged with electricity. Therefore, this study tried to examine a green image in the context of drone food delivery services. More specifically, this study proposed that a green image of drone food delivery services plays an important role in the formation of attitude toward using the services. In addition, it was hypothesized that the attitude has a positive influence on behavioral intentions including intentions to use, word‐of‐mouth intentions, and willingness to pay more. Lastly, the moderating role of gender and age was proposed during the theory‐building process. A theoretical model, which included 12 hypotheses, was developed and tested using a total of 427 samples collected in Korea. The data analysis results showed that a green image of drone food delivery services has a positive influence on attitude toward using the services, which in turn positively affects three subdimensions of behavioral intentions. Furthermore, gender and age played partly as a moderator. The current paper was the first to study the green image of drone food delivery services, so the findings of this study mean a lot to the theoretical aspect.     

Why Do They Keep Coming Back? The Effect of Push Motives vs. Pull Motives,and Attribute Satisfaction on Repeat Visitation of Tourist Destinations

We conjecture that attribute satisfaction, push motives and pull motives will be positively related to return visitation of tourist destinations. We also hypothesize that push factors will be stronger related to return visitation of tourist destinations than pull factors, both directly and indirectly as mediators of the relationship between attribute satisfaction and return visitation. In addition, we predict that age and gender will moderate the effect of push and pull factors on repeat visitation. Finally, we argue that push factors and pull factors will be mutually reinforcing. To test these hypotheses, we conducted an online survey of repeat tourists’ motives, and received 986 complete responses. Survey participants were randomly chosen from a group that met a series or qualifying questions. PLS-SEM analysis of the data showed that, as we hypothesized, attribute satisfaction and push motives were positively related to repeat visitation. In contrast, pull motives were not related to repeat visitation, either directly or indirectly, but did reinforce the effect of push motives; gender did not moderate either push or pull motives and age moderated only pull motives. We discuss the theoretical and practical implications of these findings.     

A destination imagery processing model: Structural differences between dream and favourite destinations

The present paper aims at understanding how destination imagery is processed in tourists’ working memory. The research focuses on two highly desirable, but contrasting, destination brand categories: Favourite Destination, which involves retrospective memory of positive experiences in situ; and Dream Destination, based on tourists’ prospective memory. Through an online multilingual survey, 23,446 responses consisting of perceptions, evoked by way of free-recall, associated to Dream and Favourite Destinations, were collected. Findings point to clear structural differences between the imagery of Dream and Favourite Destinations. Additionally, a theoretical destination imagery model that offers a basis for future studies is proposed, and some managerial implications of significant relevance to destination marketing are discussed.     

碳排放交易制度的节能减排路径：效率提升还是结构转型？——来自中国省级数据的准自然实验

以中国2013年以来实行的碳排放交易试点政策作为准自然实验事件，基于2000-2017年中国30个省市的面板数据，运用双重差分法实证检验碳排放交易制度的节能减排效应及影响机制。研究发现，碳排放交易制度有利于实现中国经济“节能”与“减排”的双重目标，并通过了一系列稳健性检验；作用机制检验表明，能源效率提升和能源结构转型都是碳排放交易制度实现节能减排目标的重要路径；能源效率提升在碳排放交易制度实现“节能”和“减排”中分别发挥了10.19%和5.93%的作用，而能源结构转型分别发挥了48.87%和52.95%的作用。这意味着中国碳排放交易制度实现节能减排的主要动力来自能源结构转型，而非能源效率提升。能源结构转型涉及问题更加宏观和深层，这为中国加快推进节能减排进程，特别是完成2030年碳达峰和2060年碳中和的国际承诺提供政策启示。     

Structural transformation in emerging economies: leading sectors and the balanced growth hypothesis

The paper uses the World Input-Output Database to address patterns of structural transformation in BRIC countries, Indonesia, South Korea, Mexico and Turkey. Sectoral drivers of aggregate labour productivity growth, and the relative importance of within-sector versus employment reallocation effects on aggregate labour productivity growth, are evaluated using growth accounting decomposition methods. Decomposition results are used to assess how patterns of structural transformation relate to macroeconomic performance in terms of aggregate labour productivity, output and employment growth. Together with the construction of ‘Hirschman compliance indices’, decomposition results are also used to shed light on the balanced versus unbalanced growth debates. The paper goes on to assess the extent of complementarities between manufacturing and information and communications technology-intensive advanced services through intermediate inputs, comparing the eight emerging countries with G7 countries over time.     

资源依赖型地区产业转型的战略及对策研究

资源依赖型地区产业转型是保障国家资源安全和促进经济社会可持续发展的关键。我国资源依赖型地区数量多且分布广,现阶段此类地区开发阶段不同,所以进行产业转型的路径存在差异,其过程任重而道远。针对我国资源依赖型地区产业发展的现状进行分析并找出其问题,基于此,科学全面的探讨适合此类地区实现产业转型的五个战略,并进一步分别从地区资源开发阶段和地区利益相关主体两个维度,制定出符合资源依赖型地区产业转型的对策。     

Labor market analysis through transformations and robust multivariate models

The work presents a robust approach to labor share analysis. The estimate of labor share presents various complexities related to the nature of the data sets to be analyzed. Typically, labor share is evaluated by using discriminant analysis and linear or generalized linear models, that do not take into account the presence of possible outliers. Moreover, the variables to be considered are often characterized by a high dimensional structure. The proposed approach has the objective of improving the estimation of the model using robust multivariate regression techniques and data transformation.     

谈体育教学改革发展趋势

体育教学“以人为本”观念形成的社会环境是现代化发展的必然结果。我们教育改革思路提出“健康第一”的指导思想，同样验证了“以人为本”的现代体育观念的社会环境背景。学生对体育课的要求和看法将对体育教学改革提供“主体”依据，体育教学改革要“以人为本”。