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Error quantification of a high-resolution coupled hydrodynamic-ecosystem coastal-ocean model: Part 2. Chlorophyll-a, nutrients and SPM 总被引:1,自引:0,他引:1
J. Icarus Allen Jason T. Holt Jerry Blackford Roger Proctor 《Journal of Marine Systems》2007,68(3-4):381-404
Marine systems models are becoming increasingly complex and sophisticated, but far too little attention has been paid to model errors and the extent to which model outputs actually relate to ecosystem processes. Here we describe the application of summary error statistics to a complex 3D model (POLCOMS-ERSEM) run for the period 1988–1989 in the southern North Sea utilising information from the North Sea Project, which collected a wealth of observational data. We demonstrate that to understand model data misfit and the mechanisms creating errors, we need to use a hierarchy of techniques, including simple correlations, model bias, model efficiency, binary discriminator analysis and the distribution of model errors to assess model errors spatially and temporally. We also demonstrate that a linear cost function is an inappropriate measure of misfit. This analysis indicates that the model has some skill for all variables analysed. A summary plot of model performance indicates that model performance deteriorates as we move through the ecosystem from the physics, to the nutrients and plankton. 相似文献
995.
Forng-Chen Chiu Wen-Chuan Tiao Jenhwa Guo 《Journal of Marine Science and Technology》2007,12(4):203-217
It is well known that the hydrodynamic responses of a high-speed vessel traveling in regular head waves of even moderate wave
height can show significant nonlinear behavior, and so linear statistical techniques become insufficient for predicting the
statistics of responses in irregular waves. On the other hand, it has been shown that an approximate third-order Volterra
model is applicable to handling the statistics of some nonlinear seakeeping problems, such as motions and vertical hull girder
loads. In the present study, the focus is on the nonlinear behavior of the pressure responses of the hull surface, especially
on the pressures acting on alternately wet and dry areas near the waterline and on the bow zone with high deadrise angles
that may be subject to slight impact and water pile-up effects. To clarify the validity of applying Volterra modeling to this
problem, a series of experiments in regular and irregular head waves were carried out, and approximate third-order and fifth-order
Volterra models with the proposed algorithm for finding frequency response functions (FRFs) were applied as a means of validation.
In the present article, the first part of the validation was performed using experimental data in regular waves. It was confirmed
that the third-order Volterra model has adequate accuracy to simulate deterministically the variation of pressure responses
in regular waves of different wave steepness up to a wave amplitude to wavelength ratio of 0.01 even for the highly nonlinear
pressures acting on the above-mentioned areas of the hull surface. 相似文献
996.
太平洋航线集装箱货流量GM(1,1)-马尔可夫链预测方法探讨 总被引:1,自引:0,他引:1
运用灰色系统理论对太平洋航线集装箱货流量进行定量预测,并结合马尔可夫预测方法对航线运量进行定性分析,达到定量与定性预测相结合的目的,使预测结果更加合理。采用马尔可夫链划分系统的状态,得出状态转移概率矩阵,分析了太平洋航线集装箱货流量的发展变化区间并预测集装箱航运市场的发展前景。 相似文献
997.
通过对己有各种单桩计算方法的研究总结,建立了单桩计算新理论。该理论与以往基于荷载传递法的单桩计算方法相比,做了如下改进:(1)桩侧与桩端采用广义荷载传递模型;(2)引入混凝土的Rusch模型以考虑高荷载水平作用下桩身混凝土的弹塑性性状;(3)耦合Mindlin解答以考虑桩侧摩阻力在桩端处产生的桩端位移。因此该单桩荷载-沉降关系计算方法在理论上更趋完善,使基于荷载传递法的多层地基中单桩荷载-沉降关系计算方法得到完善和统一。 相似文献
998.
以集装箱装卸设备采购工作为例,探讨项目管理中的约束条件(范围、费用、时间)与质量管理之间的关系,分析它们之间的相互作用和影响. 相似文献
999.
时间/压力型流体点胶技术在半导体封装过程中有着广泛的应用。由于胶液的非牛顿特性和点胶过程的时变特性,很难建立精确实用的点胶模型。本文通过分析过程参数(胶体体积)变化对系统性能的影响,提出了点胶过程分段变参数模型,并利用该模型对实际点胶系统进行了分段控制。仿真和实验验证了模型与控制的有效性。 相似文献
1000.
V. Pracny M. Meywerk A. Lion 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(1):1-14
The method of numerical multi-body simulation is an often used and well-understood development tool in the automotive industry. In order to reproduce the ride comfort or handling behaviour of vehicles, mathematical models have to be built up. To achieve accurate simulation results, highly detailed component models are required. However, the formulation of appropriate physically-based model equations of complex automotive components (e.g. air springs, shock absorbers, rubber bearings, tyres, etc.) can be very difficult. To handle this, empirical modelling methods have been developed. Simple algebraic equations are used to describe complex system behaviour. This simplification is very effective, although it largely ignores the natural laws of mechanics and thermodynamics but is still capable to predict the component response. This article illustrates how to take advantage of this approach in numerical simulations. We describe the development of a hybrid automotive shock absorber model based on both spline and neural network (NN) approaches. By combining these different approaches, an accurate model is achieved without loss of variability. Non-isothermal laboratory force-displacement measurements of an automotive shock absorber are being used to estimate the parameters of the NN. As shown, the model replicates the measured data with sufficient accuracy, especially the hysteresis. Finally, we present a set of quarter-car simulations with a built-in hybrid NN shock absorber. 相似文献