Bilevel optimization for the reorganization of inland river ports: A niche perspective

To address the problems of duplicate construction, disorderly competition, small scale, and weak functionality, we examine the reorganization optimization of an inland river port group to realize its coordinated development. Considering port customers' decision-making behaviors, we propose a bilevel programming model for inland river port group reorganization based on niche theory. More specifically, an upper-level model is used to develop a reorganization plan, including the inland river port spatial layout and expansion extent, to maximize the value contributed by the port group to its region and industry and minimize the competition among the ports from the perspective of port management. More specifically, two upper-level objectives can be creatively measured by niche breadth and niche overlap. A lower-level model oriented to port customers aims to reduce their respective logistics costs by designing a transportation plan and providing feedback to the upper-level model to facilitate adjustments for port group reorganization. Since the dynamic interaction between the upper- and lower-level models significantly increases model complexity, we develop a hybrid heuristic algorithm by incorporating a genetic algorithm and an exact solution method. To verify the applicability of the proposed model and the efficiency of the developed hybrid approach, we conduct a series of numerical experiments on a real-world case study concerning Jining City, Shandong Province, China. Our case study also provides managerial insights into investment scale, land-use intensification, and the balance of planning objectives that may be useful for port managers.     

基于系统基模的国家公园游憩可持续发展探析

针对中国国家公园游憩活动可持续发展过程中存在的游客数量增长上限、游憩活动的负面影响和社区参与3个较为突出的未解决问题，分别构建系统基模加以解释，并提出解决策略：一是通过加大政府的投入、适当发展特许经营和降低游憩活动的负面影响来提高国家公园的接待能力；二是通过强化对游客的教育来缓解国家公园游憩活动带来的生态环境问题和资源破坏问题；三是通过采取合理的社区参与方式来提高国家公园的接待能力和游客满意度。     

河长制对重污染企业绿色转型策略的影响

基于中国重污染上市企业2008—2019年数据和河长制演进数据,采用双重差分法考察河长制对重污染企业绿色转型策略的影响。实证研究结果表明,受河长制导致的环境监管压力的影响,重污染企业更倾向于采取绿色并购的外部获取策略、而非绿色技术创新的内部研发策略来实现绿色转型；当重污染企业面对较大媒体压力或环境不确定性较低时,影响程度更为明显；从后续机制检验结果可以看出,河长制实施后地方政府可能通过收紧环境规制促使企业绿色转型。地方政府应当制定明确的环境治理目标,并通过制度支持和制度压力等方式督促重污染企业节能减排,从源头缓解污染问题。