共查询到19条相似文献,搜索用时 250 毫秒
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随着旗台作业区及南北防波堤工程的建成,连云港港主港区已经变成为南北短、纵深长的半封闭的狭窄港域,口门的缩窄以及口门至港池末端纵深进一步增加,势必对港内水体的交换能力带来一定的影响。通过三维数学模型对工程前后的水体交换能力进行模拟,分析水体交换能力变化的原因,并通过港内水质点的Lagrange运动轨迹进一步认识港内水体的交换过程。模拟结果表明,港区内受水流动力及港口形态的影响,旗台作业及防波堤工程建设后主港区的半交换周期从约5 d增加至22 d。为了保障港内水域的水质环境,必须严格控制港内水体污染排放。 相似文献
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港口建设会造成一定的海洋环境影响,使得周边海域的水动力条件发生改变,对水环境质量也会产生影响。采用平面二维数值模型MIKE21FM,预测了港口建设后对水动力环境的影响。通过添加平面二维非恒定的对流-扩散模块,进行悬浮物扩散预测。废水排放预测采用物质输运方程,通过差分数值模拟方法模拟典型污染物浓度场,分析了废水排放对水质的影响。在围堰的掩护作用下,港区内涨落潮流速均有较大幅度的降低,各港池内的流速均在0.25 m/s以下。围填海疏浚影响主要集中于疏浚作业点周围300 m范围内,且废水排放各类污染物的最大扩散范围控制在400 m以内。结论可为港口区域规划、设计、建设提供参考和依据。 相似文献
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建立了渤海平面二维水动力数学模型和平面二维对流扩散模型,使用有限差分的ADI方法对模型进行离散,模拟了渤海湾内规划工程建设前后的交换率,得到了渤海湾水交换能力的空间分布。研究结果表明,渤海湾西南部地区的水交换能力最差,规划工程实施后,渤海湾湾口至湾顶的中间带区域交换率增大,增幅最大可达50%以上,其余大部分区域交换能力减小。 相似文献
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《水道港口》2019,(6):742-747
泥沙淤积是影响港口防波堤布置方案比选的重要因素,为评价港口泥沙的淤积程度,提出基于方法集的港口泥沙淤积评价模型。首先利用数值模拟得到港池航道淤积分布,基于港池和港内外航道中的泥沙淤积分布建立了评价指标集,然后分别应用灰色关联度分析法、主成分分析法、投影寻踪、TOPSIS法对连云港徐圩港区防波堤工程的3个大环抱优化方案进行评价,并使用Kendall-W和谐系数对评价结果进行事前一致性检验,将满足一致性的评价方法构建方法集,再运用算术平均法、Borda法、Copeland法对单一评价的排序结果进行组合评价,根据事后一致性检验结果,选择最优组合评价方法的评价结果作为最终结果,最后应用该模型对连云港防波堤布置方案进行组合评价,验证了该方法的有效性。该方法可为我国类似港口的淤积评价提供借鉴。 相似文献
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The fast growth of the Chinese economy and its international seaborne trade has escalated the demand for high-quality and efficient port services. “Decentralization” of the port management regime has given local government greater freedom in port development and operational decision-making. However, major port capacity expansion in coastal areas, coupled with the slowing down of both the economy and trade growth over recent years, has led to overcapacity and excessive competition. Although both port specialization and government regulations are called for to address these issues, few studies have investigated the formation mechanism and economic implications of port specialization. This paper uses alternative duopoly games, namely a Stackelberg game and a simultaneous game, to model port competition, where ports provide differentiated services in the sectors of containerized cargo and dry-bulk cargo. Our analytical results reveal that inter-port competition can lead to port specialization in the following three ways. A port can specialize in a type of cargo (1) for which there is relatively high demand, (2) where it has established capacity first, or (3) for services which require prohibitively high capacity costs. Also, it is seen that overcapacity is likely if strategic port decisions are made simultaneously instead of sequentially. These results suggest that if there is a clear market leader, policy intervention may not be necessary. However, if no port has clear market power, then government coordination and intervention may be needed in order to prevent overcapacity and to encourage specialization. 相似文献