大跨悬索桥主缆线形解析迭代法研究

基于悬索桥在恒载作用下的受力特点,建立了主缆线形控制计算的解析迭代方法,以此确定主缆无应力长度、成桥线形、空缆线形。算例结果表明该解析法具有适合程序计算、收敛速度快、计算精度高的特点,可用于悬索桥设计与施工控制计算。     

煤合成柴油(F-T柴油)在柴油机上的试验研究

试验研究了单缸柴油机燃用F-T柴油和0号柴油的燃烧特性和排放特性。与发动机燃用0号柴油相比，燃用F-T柴油时燃油消耗率降低，有效热效率升高，有害排放降低，结果表明，F—T柴油是一种高品质的柴油机代用燃料。     

Numerical modeling of ground response during diaphragm wall construction

Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsolidated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mechanical response of ground, including horizontal normal stress and shear stress, lateral ground displacement and vertical ground surface settlement, during the slurry trenching and concreting of diaphragm wall panels. Numerical results show that slurry trenching leads to horizontal stress relief of ground, reducing the horizontal stress of the ground from initial K0 pressure to hydrostatic betonite pressure. Wet concrete pressure lies between the hydrostatic bentonite pressure and the initial K0 pressure, so it can compensate partially the horizontal stress loss of the ground adjacent to the trench and thus reduce the lateral movement of the trench face as well as the vertical settlement of the ground surface.     

Analytical Approach to Evaluating Transit Signal Priority

Successful deployment of transit signal priority (TSP) systems requires thorough laboratory evaluation before field implementation. Traffic simulation is a powerful tool in this regard; however, it requires tremendous efforts toward network coding, data collection, and model calibration. Besides, simulation models tend to be project specific, and the models developed for one project are often discarded upon the completion of that project. In this paper, it is shown that the impacts of two fundamental TSP strategies (early green and extended green) can be evaluated using an analytical approach. The impacts of the above two strategies on both the prioritized and the nonprioritized approaches are illustrated using graphical as well as analytical methods. A simulation study is then conducted for comparison analyses, followed by a statistical approach for the test of generality.     

Numerical Simulation of Float-Over Installation for Offshore Platform

In this paper, a numerical investigation of a float-over installation for an offshore platform is presented to verify the feasibility of the actual installation. The hydrodynamic performance of a T-barge is investigated in the frequency domain, and the coupled motions are analyzed in the time domain. We then compare with those of the model test and determine that the response amplitude operator and the time series agree quite well. The barge exhibits favorable hydrodynamic behavior in the considered sea state, and the equipment loads are allowable. The mooring system and sway fender forces are within the permissible range. Based on these results, we can verify that the actual installation of the offshore platform is feasible. We accurately simulated many important factors and effectively reduced the risk associated with the offshore installation, which is of great importance. As such, we demonstrate that the numerical simulation of the float-over installation for offshore platforms has practical engineering significance.     

Spectral Wave Modeling in Very Shallow Water at Southern Coast of Caspian Sea

This study evaluates the capability of the Simulating WAves Nearshore (SWAN) wave model (version 41.01) in predicting significant wave height and spectral peak energy content for swell waves in very shallow water of surf zone during depth-induced wave breaking and dissipation. The model results were compared with field measurements at five nearshore stations. The results demonstrated that some breaker index formulations were successful for significant wave height prediction in surf zones. However, an incorrect shape of the energy spectrum and overestimated near spectral peak energy content at shallow water stations were obtained using all of the embedded depth-induced wave breaking formulations in SWAN. The dependent breaker index on relative depth (K_pd) formulation, which was successful in predicting near spectral peak energy content, resulted in an average error of 30%. Finally, this formulation was modified to enhance the model performance in reproducing the spectral peak energy content.     

CFD Analysis of Ship-to-Ship Hydrodynamic Interaction

A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code, and the results are compared with experimental data and with the results of a panel method analysis. Two ship models have been used in the interaction forces analysis: a tug and a tanker, advancing parallel to each other with different lateral distances and two different values of the fluid depth. Computations are carried out with four different flow models: inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface. A fair agreement was obtained with available experimental data and results obtained by panel method. The influence of viscosity in the computations is found to be comparatively weak, while the wavemaking effects may be important, at small magnitude of the horizontal clearance.     

Trapped Modes in a Three-Layer Fluid

In this work, trapped mode frequencies are computed for a submerged horizontal circular cylinder with the hydrodynamic set-up involving an infinite depth three-layer incompressible fluid with layer-wise different densities. The impermeable cylinder is fully immersed in either the bottom layer or the upper layer. The effect of surface tension at the surface of separation is neglected. In this set-up, there exist three wave numbers: the lowest one on the free surface and the other two on the internal interfaces. For each wave number, there exist two modes for which trapped waves exist. The existence of these trapped modes is shown by numerical evidence. We investigate the variation of these trapped modes subject to change in the depth of the middle layer as well as the submergence depth. We show numerically that two-layer and single-layer results cannot be recovered in the double and single limiting cases of the density ratios tending to unity. The existence of trapped modes shows that in general, a radiation condition for the waves at infinity is insufficient for the uniqueness of the solution of the scattering problem.     

Bridge officers’ non-technical skills: a literature review

The present review examines the research literature on Non-Technical Skills (NTS) used by ships’ bridge officers in connection with navigation. The aim of the study was to (i) identify the cognitive and interpersonal skills which have been the focus of previous studies and (ii) explore how the content of these skills has been described. Databases searched included Academic Search Premier, PsycINFO, Science Direct, and Web of Science. Nineteen studies were included in the review. Five NTS were identified: situation awareness (SA), decision-making (DM), workload management (WM), communication, and leadership. In addition to discussing each skill, the review raises four overarching issues with the present literature for the bridge domain: (1) Have all the relevant skills been subject to exploration? (2) Have the skills identified been explored in detail? (3) There seems to be an uneven distribution of research between cognitive and interpersonal skills. (4) There is little research into understanding the skills as a complete taxonomy. Knowledge on how the skills are linked and interplay with one another is incomplete. Overall, further research on all these aspects of NTS in the maritime domain could increase scientific understanding and contribute to bridge operational practice and to the further development and evaluation of NTS training such as Bridge Resource Management (BRM).