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The sustainable development goals (SDGs) suggest sustainable cities and communities (Goal 11) as inclusive, safe, resilient, and sustainable human settlements. However, existing efforts in urban sustainability have mainly focused on ecological and environmental sustainability, with little attention paid to development, economic, and cultural sustainability. Moreover, a lack of adaptability is a barrier to cross-nation or cross-region implementation of many urban sustainability frameworks due to diverse urban contexts. Furthermore, most studies have developed sustainability frameworks and guides only for one-time assessments and the progress of urban sustainability has been neglected. Improving urban sustainability by considering multiple dimensions and local adaptability through dynamic assessment remains a question. Therefore, this study aims to develop an urban environment examination system (UEES) framework that includes construction, economy and industry, environment and resource, municipal and cultural facilities, and development potential dimensions. The UEES framework consists of 31 indicators associated with critical information (i.e., reported by the statistical yearbooks) from different levels of government in China. An annual update of statistical data ensures the availability of dynamic data, allowing urban managers and decision makers to regularly track urban sustainability. Furthermore, the UEES framework was applied to Qingdao, an urbanizing city in China, to examine the feasibility of the UEES framework. The results indicate that well-urbanized districts could perform better in terms of overall sustainability (e.g., Shinan, Shibei, Laoshan, Chengyang), while districts in suburban and outer suburban areas had lower urban sustainability levels. However, well-urbanized districts could not perform better in all dimensions than suburban and outer suburban districts. Moreover, the transition from less-urbanized to well-urbanized districts could lead to environmental deterioration and economy deceleration (if industries are not well upgraded), but culture and development sustainability can be improved. Overall, this study provides a methodological framework that prioritizes comprehensiveness and local adaptability to perform regular urban environment examinations for urban sustainability in China and provides a reference for urban sustainability improvement by identifying aspects with low scores in Qingdao, China. [ABSTRACT FROM AUTHOR]

In this paper, we study the portfolio selection problem considering the uncertain investment time horizon. We employ the Period Value at Risk (PVaR) to characterise the risk in the special cases and establish a fundamental mixed integer linear programming (MILP) model to obtain the optimal portfolio solutions. Identifying that the symmetric property of PVaR can significantly reduce the computation burden of the CPLEX solver, an enhanced MILP model is proposed. To verify the quality of obtained solutions, we also develop fast lower and upper bound estimation schemes respectively. Using the real-world data sets from NYSE and NASDAQ stock markets, numerical results are provided to show the efficiency of the enhanced model. [ABSTRACT FROM AUTHOR]

Quantity discount is a frequently adopted scheme that has not been explicitly investigated in logistics service procurement auctions. This paper focuses on a revised winner determination problem under quantity discounts and demand uncertainty for a fourth-party logistics (4PL) provider in a combinatorial reverse auction. To characterize our research problem, a two-stage stochastic nonlinear programming model is constructed. Inspired by the idea of sample average approximation (SAA), the nonlinear model is reformulated as a deterministic mixed integer linear programming model by using a linearization technique with superior expressions. Since the reformulation has a large number of decision variables and constraints, we integrate SAA with a dual decomposition Lagrangian relaxation technique (DDLR) to develop a solution method called SAA-DDLR. Numerical experiments are conducted to illustrate the effectiveness and applicability of our model and method. Sensitivity analysis reveals that both the 4PL and 3PLs can benefit from the quantity discount scheme. Managerial insights are drawn for the 4PL to run a cost-effective logistics system in the presence of quantity discounts. [ABSTRACT FROM AUTHOR]