船东投资新价值取向

金融危机以来,航运和造船市场格局发生了巨大变化,船东在新船投资上也出现了一些新的特点和趋势。在全球新船投资中,欧洲船东所占份额在各主要船东所在区域中名列第一,其在建船舶约占据50%的份额。其次是亚洲船东,该地区船舶投资增长幅度仅次于欧洲地区,其在建船舶约有30%的份额。     

双向碳纤维网格在上海堤防维修加固工程中的应用

堤防结构定期维修加固是预防安全隐患,确保堤防设施安全运行的重要手段。结合双向碳纤维网格在上海堤防设施维修加固工程的首次应用实例,介绍了碳纤维网格加固方法,分析了碳纤维网格加固系统在堤防维修加固工程中的适用性和先进性,探究了碳纤维网格受弯加固原理,推导了受弯承载力计算公式并验证了公式的正确性,为类似堤防维修加固工程提供参考和借鉴。     

中美隧道二次衬砌结构设计规范对比研究

隧道设计规范是开展设计工作的依据,将我国隧道相关设计规范与国际先进国家技术标准对标,有助于提高我国工程建设企业的国际化竞争力。通过文献调研和计算分析对比研究了中美隧道二次衬砌结构设计的异同,并且从设计准则、极限状态划分、设计使用年限、材料特性、荷载分类和组合以及结构设计方法等方面展开对比,结合工程实例研究分析,结果表明：《公路隧道设计规范》（JDG 3370.1—2018）的设计参数更加保守、安全,能更好的保证隧道衬砌结构的安全性和耐久性,更有利于隧道二次衬砌的长期安全服役。     

Exploring passenger anxiety associated with train travel

Although people are often encouraged to use public transportation, the riding experience is not always comfortable. This study uses service items to measure passenger anxieties by applying a conceptual model based on the railway passenger service chain perspective. Passenger anxieties associated with train travel are measured using a modern psychometric method, the Rasch model. This study surveys 412 train passengers. Analytical results indicate that the following service items cause passenger anxiety during trains travel: crowding, delays, accessibility to a railway station, searching for the right train on a platform, and transferring trains. Empirical results obtained using the Rasch approach can be used to derive an effective strategy to reduce train passenger anxiety. This empirical study also demonstrates that anxiety differs based on passenger sex, age, riding frequency, and trip type. This information will also prove useful for transportation planners and policy-makers when considering the special travel needs of certain groups to create a user-friendly railway travel environment that promotes public use.     

Ship underwater noise assessment by the acoustic analogy,part III: measurements versus numerical predictions on a full-scale ship

The acoustic analogy represents a powerful and versatile approach, able to numerically predict the noise generated by a body moving in a fluid. It is widely used to provide essential indications about the aeroacoustic behavior of aircraft and helicopters (even at a design stage) and, eventually, to pursue effective strategies aimed at desirable reduction and/or control of noise. Nevertheless, applications in the area of hydroacoustics and in the prediction of ship underwater noise are very rare. In this paper, the potential of the acoustic analogy is directly tested on a large ferry, for which a measurement campaign at sea was performed. In spite of the complexity of the tested configuration [the ship mounts two contracted and loaded tip (CLT) propellers located ahead of two rudders, and its hull is characterized by a rather elongated skeg] and the many variables not taken into account in the numerical simulation (such as the contribution from machinery noise and the probable occurrence of tip vortex cavitation), the agreement between the measured and computed noise spectra is quite satisfactory. The analysis suggests many interesting features of the ship hydroacoustic field: the dominant role played by nonlinear sources far from the body and the relevance of scattering effects from the hull surface. Furthermore, the scattered pressure seems to contribute to alter the frequency content of the resulting signatures with respect to the blade passage frequencies. Finally, an overview of future developments and applications of this numerical approach for marine/maritime problems is presented.     

影响现代手动变速器性能的技术

带同步器的手动变速器常规的机械设计和功能尽管多年来没有变化,但是诸如齿轮、轴承、密封、同步器,以及润滑油等所有组成部分都在不断地改进,产品的质量持续提高。本文研究的,是润滑油对同步器材料摩擦和磨损性能的影响。最近几年,同步器的材料已经多样化,从黄铜、钼基产品到烧结材料,每种合成物提供给设计者不同的磨损和耐久特性。尽管烧结铜是像黄铜一样的铜合金,但润滑油的反应却未必相同。因此,需要不断地修正润滑油成分,以获得匹配同步器材料的最佳效果。为了使变速器系统综合功能最佳,润滑液的流变性和化学特性处于平衡状态是必须的,氧化和密封性能也应该表现优异。     

汽车电子电器故障检测技术

汽车装配完成后需要进行全面的电子电器功能检测。我们采用了一种设备半自动检测方法,这种方法:分为电器检测部分和电子检测部分。电器检测部分采用测量电器功率消耗来判断被检测电器是否正常。电子检测部分包括车辆电控单元(ECU)及传感器故障检测、ECU间的连接检测、ECU植入软件检测、ECU零件错装检测、ECU配置信息检测以及车身内部电器件运行检测等检测项。这种检测方式在生产中被证实是一种非常有效的检测方法:。     

汽车产业转移的“后雁模式”

1雁形模式到后雁模式的过渡雁形模式是产业转移的一种选择,是基于产业转移过程特征的一种模式。雁形转移模式是日本经济学家赤松要从产业转移的过程特征或形态的角度归纳出来的著名模式。赤松要以发展中国家为视角分析了发达国家和日本之间的产业空间转移现象,归纳出产品进     

基于坐垫体压分布的驾驶员生理状态识别方法

提出一种基于坐垫体压分布识别长途驾驶过程中驾驶员生理状态的方法.开展长途驾驶模拟试验,采集9名被试者在驾驶过程中的坐垫体压分布数据,提取82维分类特征,再采用序列浮动前向选择算法从中选出55维最优特征子空间.试验结果表明,该方法能准确识别驾驶员生理状态,贝叶斯分类正确率可达93.37％.