基于Optimoor的内河码头船舶运动量下系泊分析

与沿海码头相比,内河码头船舶系泊作业受水流影响更为显著,且流向多为顺流。通过系泊仿真试验,以允许船舶系泊作业时的最大运动量为控制标准,分析允许船舶系泊作业时的各项限制条件,尤其是限定的水流条件。现行《规范》对码头系泊作业时基于船舶运动量下的限制波浪、风速、水流等未予以明述,本文研究结果可为相关船舶系泊作业提供理论参考。     

冲积黏土对格型钢板桩振沉施工的影响

格型钢板桩在黏土的施工过程中,地质环境和施工工艺的影响因素会因钢板桩锁扣之间的拉力过大而导致施工困难。结合港珠澳大桥香港口岸人工岛项目的格型钢板桩施工进行分析,给出根据项目CPT试验结果进行施工难度分析的量化指标,为类似工程的施工提供借鉴。     

三维竖轴潮流水轮机水动力性能研究

竖轴水轮机作为潮流能转换为电能的核心装置,其水动力性能的优劣将会直接影响到整体发电系统的效率。为了研究大型竖轴水轮机叶片安装角对水轮机水动力性能的影响,基于多参考系模型(MRF),采用Fluent软件对流场中的模型进行3D数值模拟。在转速和来流速度保持不变,改变安装角时,分析同种翼型5个不同安装角叶片对潮流能水轮机的水动力性能的影响。同时分析在同一安装角和旋转速度条件下,不同来流速度对水轮机水动力性能的影响。结果表明,叶片安装角对竖轴潮流水轮机的能量利用率影响较大,来流速度对水轮机叶片表面的静压力和输出功率具有一定的影响。研究结果对今后竖轴水轮机的设计和生产具有借鉴意义。     

A methodology for identifying similar days in air traffic flow management initiative planning

This article describes a methodology for selecting days that are comparable in terms of the conditions faced during air traffic flow management initiative planning. This methodology includes the use of specific data sources, specific features of calendar days defined using these data sources, and the application of a specific form of classification and then cluster analysis. The application of this methodology will produce results that enable historical analysis of the use of initiatives and evaluation of the relative success of different courses of action. Several challenges are overcome here including the need to identify the appropriate machine learning algorithms to apply, to quantify the differences between calendar days, to select features describing days, to obtain appropriate raw data, and to evaluate results in a meaningful way. These challenges are overcome via a review of relevant literature, the identification and trial of several useful models and data sets, and careful application of methods. For example, the cluster analysis that ultimately selects sets of similar days uses a distance metric based on variable importance measures from a separate classification model of observed initiatives. The methodology defined here is applied to the New York area, although it could be applied by other researchers to other areas.     

超声波流量计在输油管道泄漏监测系统中的应用

为提高负压波法管道泄漏监测系统的报警可靠性,有必要将超声波流量信息引入管道泄漏监测系统。为保证管道泄漏监测系统中超声波流量计的应用效果,分析了超声波流量计的测量原理和测量精度影响因素,总结了输油管道超声波流量计在选型设计、现场安装及运行维护等方面的应用经验。开展了基于超声波流量计的管道泄漏监测技术的现场应用测试和结果分析,测试结果表明超声波流量计对提升管道泄漏监测系统报警可靠性具有显著作用。     

Short‐term traffic flow prediction with linear conditional Gaussian Bayesian network

Traffic flow prediction is an essential part of intelligent transportation systems (ITS). Most of the previous traffic flow prediction work treated traffic flow as a time series process only, ignoring the spatial relationship from the upstream flows or the correlation with other traffic attributes like speed and density. In this paper, we utilize a linear conditional Gaussian (LCG) Bayesian network (BN) model to consider both spatial and temporal dimensions of traffic as well as speed information for short‐term traffic flow prediction. The LCG BN allows both continuous and discrete variables, which enables the consideration of categorical variables in traffic flow prediction. A microscopic traffic simulation dataset is used to test the performance of the proposed model compared to other popular approaches under different predicting time intervals. In addition, the authors investigate the importance of spatial data and speed data in flow prediction by comparing models with different levels of information. The results indicate that the prediction accuracy will increase significantly when both spatial data and speed data are included. Copyright © 2016 John Wiley & Sons, Ltd.     

柔性隔振系统功率流传递特性研究

由于基础和隔振器存在着动力耦合,经典隔振理论的局限性日益突出,从而出现了将基础简化为欧拉梁、柔性板、圆柱壳等。本文将基础简化为两端固支弹性梁,运用四端参数法推导了单层柔性隔振系统传递功率流,并运用电力类比法对推导结果进行了验证。通过数值仿真,分析了偏心激励对功率流传递特性的影响,并将功率流与振级落差频谱曲线进行了比较。结果表明：偏心激励会激发系统的高阶模态,基础的刚性会影响振级落差对功率流的估计。     

水流速度对内河船舶营运能效影响分析

本文在能源消耗和环境污染的危机下,致力于内河船舶能源消耗和温室气体排放的研究,分析了水流速度对内河船舶营运能效的影响。本分析是基于一艘客船的数据进行的,分别对不同航段下水流速度,主机转速,燃油消耗进行测量,并计算得到内河船舶营运能效。根据测量结果提出内河船舶营运能效提升策略,为内河航运业的节能减排提供帮助。     

海洋平台桩基安装过程对土阻力的影响分析

提高桩基可打入性预测的精度一直是海洋工程界普遍关心的问题。影响桩基可打入性分析结果的因素有很多,很多学者对此进行了研究,但受到各种因素的限制,对于打桩过程的影响鲜有涉及。针对某海域现场两根试验桩的实测数据、室内试验数据和现场CPT结果,采用波动方程方法对在砂土中进行打桩时的打桩过程对打桩土阻力(SRD)的影响进行了研究。分析结果显示:在砂土中,即使桩径达到2.438m仍然可以形成闭合的土塞;相同土质条件下,打桩过程中不同的锤击能量导致了不同的锤击数,并进一步产生了SRD的差异,这说明打桩所导致的侧阻退化程度与打桩过程有关。CPT方法用于评价砂土中打桩的SRD的精度优于传统方法。在本次试验条件下,对于形成土塞的情况,ICP方法的计算结果偏小。     

小型汽轮机调节汽阀振动分析与改进研究

针对某小型发电用汽轮机调节汽阀在低负荷工况下出现的汽流噪声和振动问题,研究分析了问题产生的原因,采取了加装调节汽阀保护套的现场解决措施,并进行了试验验证,同时从改进调节汽阀结构和装配工艺方面提出了进一步的优化解决方案。