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61.
62.
The Haskind-Hanaoka relations for obtaining the wave-exciting forces, given the incoming and radiation potentials in floating rigid-body dynamics, are extended to deformable-body dynamics in the presence of a free surface and within the assumption of linear potentials theory. These relations are applied to the mode-superposition and the direct methods of solution of hydroelasticity problems. In other words, it is shown that regardless of the structural analysis method used in a hydroelasticity problem, the Haskind-Hanaoka relations can be used to calculate the wave-exciting forces without solving for the diffraction potential explicitly. These relations can also be used in the composite singularity distribution method to increase further the computational efficiency. 相似文献
63.
Protonmagneticresonancespectroscopy (1H MRS)isanewtechniqueoffunctionalimaginginbrainandprovidesauniquenoninvasivetoolforex aminingmetabolisminvivonow .Inrecentyear ,therearesomereportsaboutprotonMRSingrowthofbrainandhypoxia ischemicencephalopathy(HIE) [1- 4] ,butfewarticlesaboutclinicalapplica tionofprotonMRSindiagnosistumoursandtheirdifferentiationfromnon neoplasticlesions .WestudiedMRSin 38braintumorsand 14brainnon neoplasticlesions.Herewereporttheresults .MATERIALSANDMethods1 … 相似文献
64.
在贵阳轨道交通3号线盾构隧道施工中,采用普通刀具易出现滚刀多边形磨损、偏磨、刀刃崩裂等异常磨损和刀圈脱落现象。为改进滚刀刀圈的耐磨、耐冲击性能,提高刀具的综合寿命,提出采用球状碳化钨刀具替换普通刀具,并介绍了激光熔覆焊工艺以及宏观磨损检测工艺。经过施工现场的实际应用,发现球状碳化钨刀具具有更好的耐磨性,新型球状碳化钨刀具平均磨损量为0.00255 mm/延米,相邻普通刀具平均磨损量为0.01655 mm/延米。在第338~736环掘进中,新型球状碳化钨刀具最大磨损量为0.015 mm/延米,刀具无崩刃现象,滚刀轴承、密封等均无异常,有效解决了普通刀具易磨损、磨损不均的问题,为喀斯特地质条件下盾构刀具的选型提供参考。 相似文献
65.
M. Comellas J. Pijuan X. Potau M. Nogués J. Roca 《International Journal of Automotive Technology》2013,14(1):151-161
There is a large variety of multiple driven axle vehicles. Some of the most common are the 3-axle rigid vehicles and the 4-axle articulated vehicles, which can in some cases have different steering mechanisms, adaptive suspension, etc. This last kind of vehicles usually have very complex transmission configurations. Moreover, the required torques in each of the wheels can be very different, especially when the vehicle is working in rough terrains. The aim of this work is to study and model the driveline of this kind of vehicles, when using a hydrostatic transmission, from the performance and efficiency point of view, by analysing the influence of the operating conditions in the transmission efficiency. A global model is used to quantify the power flow in each of the transmission elements and the overall performance of the entire vehicle driveline, given the operating conditions thereof. A sensitivity analysis has also been done showing the influence of vehicle speed, rolling resistance, terrain slope and hydraulic motors displacement in the overall transmission efficiency. The interest of this work is also to make a contribution to the literature in the field of global modelling of drivelines under variable operating conditions and its application to ATVs. One important aspect is the influence of different actuation requirements that occur in different wheels at the same time. The results show that the overall performance of the transmission is highly dependent on operating conditions, on the selected transmission configuration and on the used components. 相似文献
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67.
Z.L. Yang D. Zhang O. Caglayan I.D. Jenkinson S. Bonsall J. Wang M. Huang X.P. Yan 《Transportation Research Part D: Transport and Environment》2012,17(6):478-486
This paper develops a subjective generic methodology for providing ship owners with a transparent evaluation tool for selecting their preferred NOx and SOx control techniques. We quantitatively analyse the merits of the control methods available in marine air pollution control practice using data collected from shipping companies, shipyards and maritime academies. We also prioritize the applicable control techniques with respect to operational shipping environments. 相似文献
68.
The paper proposes a first-order macroscopic stochastic dynamic traffic model, namely the stochastic cell transmission model (SCTM), to model traffic flow density on freeway segments with stochastic demand and supply. The SCTM consists of five operational modes corresponding to different congestion levels of the freeway segment. Each mode is formulated as a discrete time bilinear stochastic system. A set of probabilistic conditions is proposed to characterize the probability of occurrence of each mode. The overall effect of the five modes is estimated by the joint traffic density which is derived from the theory of finite mixture distribution. The SCTM captures not only the mean and standard deviation (SD) of density of the traffic flow, but also the propagation of SD over time and space. The SCTM is tested with a hypothetical freeway corridor simulation and an empirical study. The simulation results are compared against the means and SDs of traffic densities obtained from the Monte Carlo Simulation (MCS) of the modified cell transmission model (MCTM). An approximately two-miles freeway segment of Interstate 210 West (I-210W) in Los Ageles, Southern California, is chosen for the empirical study. Traffic data is obtained from the Performance Measurement System (PeMS). The stochastic parameters of the SCTM are calibrated against the flow-density empirical data of I-210W. Both the SCTM and the MCS of the MCTM are tested. A discussion of the computational efficiency and the accuracy issues of the two methods is provided based on the empirical results. Both the numerical simulation results and the empirical results confirm that the SCTM is capable of accurately estimating the means and SDs of the freeway densities as compared to the MCS. 相似文献
69.
Transportation - City events are getting popular and are attracting a large number of people. This increase needs for methods and tools to provide stakeholders with crowd size information for crowd... 相似文献
70.
Major accidental oil spills still affect ecologically and economically sensitive marine areas and shorelines, even though environmental programs and policies have led to an increase of ship safety measures. The aim of decision making during oil spill response management is to minimize pollution effects on coastal areas, once spills occur. However, limited equipments or options prevent such a globally satisfying combat strategy. Thus, often preferences between different coastal areas or uses, respectively, have to be made in an operational way. Such a management issue is here taken as a multigroup multicriteria decision-making problem involving a variety of stakeholders and natural dynamic environments. For solving such a complex problem, this article proposes a second order fuzzy comprehensive evaluation (FCE) model, which takes the influence of multiple criteria and the knowledge of different interested groups into account and further provides a basis for simulating a voting-based decision process. With the combination of oil fate simulations and FCE technique, managers are able to realize an integrated management for oil spill. Through a case study of the Prestige accident off the Spanish coast in 2002, it is demonstrated that the model provides a simple, effective and adaptable method to solve operational management problems related to complex human nature interactions as realized during oil spill management. Moreover, a series of analyses and comparisons are focused on to explore potentials and limitations of the FCE for further applications in the field of multigroup multicriteria decision making. 相似文献