航运企业投资对码头运营效率的影响研究

随着港口投资结构多元化、航运企业向综合物流商转变,“港航合一”成为航运业未来的发展趋势.在此背景下,研究航运企业投资对码头的影响能够为码头健康发展提供一定的理论依据.本文先采用三阶段DEA模型对我国沿海集装箱码头2008–2012 年间的运营效率进行测度,其次依据投资结构将我国沿海62 个集装箱码头进行分组,最后重点分析投资结构与码头运营效率之间的关系.研究结果显示,有航运企业投资的码头运营效率普遍高于无航运企业投资的码头,两组码头的纯技术效率相差较小,而规模效率相差较大.航运企业参与码头建设经营可以实现自有船舶挂靠自有码头,提升码头设施的利用率,从而提升码头的规模效率,有利于码头的健康发展.     

An Adaptive Joint Source/Channel Coding Using Error Correcting Arithmetic Codes

An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcting in a single process, with superior performance compared with traditional separated techniques. The concept of adaptiveness is applied not only to the source model but also to the amount of coding redundancy. In addition, an improved branch metric computing algorithm and a faster sequential searching algorithm compared with the system proposed by Grangetto were proposed. The proposed system is tested in the case of image transmission over the AWGN channel, and compared with traditional separated system in terms of packet error rate and complexity. Both hard and soft decoding were taken into account.     

基于非线性规划法的最小阻力船型优化设计

为了获得阻力性能优良船型,以兴波阻力理论为基础,利用非线性规划法并结合CAD技术研究最小阻力船型的优化设计.以总阻力为目标函数,总阻力用兴波阻力和平板摩擦阻力之和来表达,设计变量取船型修改函数的参数,在保证必要的排水量为基本约束条件下,选取Wigley船型为初始船型,分别对船体的首部和全船线型进行优化设计.通过将改良船型的阻力性能、船体线型和基于Michell积分法的优化计算结果相比较,证实了在相同的设计参数和约束条件下,采用Rankine源法进行船型优化结果更可靠.     

大型交叉桥梁转体施工风险模糊控制网络

拟基于相关人员调查、评估小组讨论、专家咨询等方式建立大型交叉转体作业风险因素普查清单,通过模糊综合评判法对转体作业风险等级进行评估,从而制定出适应自身结构物、被交结构物的安全风险控制措施,最终形成转体施工安全风险模糊控制网络。     

用面元法预报船舶的兴波阻力及波型

采用基于开尔文源的面元法求解航行于均匀流场中的船舶兴波问题．在船体湿表面上布置开尔文源，使其严格满足船体表面条件．数值计算中，首先采用分部积分对被积函数进行简化处理，然后采用高斯积分实现面元和线元上的积分，避免了被积函数为高频振荡函数所带来的数值计算的复杂性和不确定性．计算结果表明，其波型及兴波阻力系数与试验结果和其他数值方法相比均吻合较好．     

Challenges and Benefits in the Design of Coastal Walking and Cycling Amenities: Toward a More Integrated Coastal Management Approach

The planning and development of pedestrian and cycling amenities in coastal urban environments is a challenging process because a wide range of policies and considerations must be taken into account. Among these, the concepts of sustainability and more recently, resilience, have been gaining prominence. Green Infrastructure design approaches can integrate aspects of both sustainability and resilience, providing multiple services within single development projects. This study focuses on Dublin and examines a range of amenity projects at various stages of development that relate to the provision of new coastal walking and/or cycle routes. These are initially contextualized at the city level before focusing specifically on challenges and benefits associated with the design and implementation of such projects. Based on our findings, recommendations are made for optimizing the potential of future projects to effectively integrate with other initiatives so as to deliver broader policy objectives. A simple sequential model is presented that should assist developers and decision-makers to take a more integrated, multidisciplinary approach to meeting policy goals when planning and developing coastal amenities. Finally, this is remodeled into a set of considerations that are generally applicable to coastal development proposals of significant scale.     

基于仿真的沿海港口甩挂场站布局方案比选

甩挂运输以其高效低碳的特点正得到迅速发展。针对当前国内甩挂场站研究中功能布局、建设规模等方面的量化研究相对不足,利用微观仿真软件VISSIM建立沿海港口甩挂运输场站交通仿真模型,研究甩挂车辆在场站内运行状况,评价场站内部功能布局方案,并以某港口为例,验证该模型的有效性。     

大型海岸工程对水流和泥沙运动的影响研究

在淤泥质海岸建设大型海岸工程,会对周边海域的水沙环境产生一定影响。文章以连云港为例,应用波浪潮流泥沙数学模型,模拟计算了连云港海域大型海岸工程实施后对于水流泥沙运动的影响。研究结果表明:连云港区、徐圩港区以及灌河口双导堤工程实施后,工程区以外的大范围海域潮流场和含沙量场基本没有改变,变化主要集中在工程区和工程区附近近岸海域,总体呈现出动力减弱、含沙量减少的趋势。     

船舶机舱空气源热泵技术应用分析

阐述了船舶节能的重要性。通过分析船舶机舱空气的特点,提出了一种利用空气源热泵对机舱余热进行回收利用的技术,进行了理论分析与计算,并与传统的船舶锅炉供热系统做了对比分析。分析了该技术的应用前景和关键问题。     

新的噪声规则对船舶噪声控制的影响

噪声作为一种环境污染越来越受到人们重视。由此海安会颁布了MSC.337(91)《船上噪声等级规则》。该规则在A.468的基础上进行修改的。对新规则与现有规则进行了比较,并通过实例分析了新的噪声规则对船舶设计的影响。重点分析了噪声源及噪声传播途径,提出了降低噪声的控制措施。