For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating cur...For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating curves are combined with the HEC-6 model to investigate the effects of river engineering measures on the Elbe River system. In such situations, the uncertainty originating from the HEC-6 model is of significant importance for the reliability of the rating curves and the corresponding DSS results. This paper proposes a two-step approach to analyze the uncertainty in the rating curves and propagate it into the Elbe DSS: analytic method and Latin Hypercube simulation. Via this approach the uncertainty and sensitivity of model outputs to input parameters are successfully investigated. The results show that the proposed approach is very efficient in investigating the effect of uncertainty and can play an important role in improving decision-making under uncertainty.展开更多
Rectification for airborne linear images is an indispensable preprocessing step. This paper presents in detail a two-step rectification algorithm. The first step is to establish the model of direct georeference positi...Rectification for airborne linear images is an indispensable preprocessing step. This paper presents in detail a two-step rectification algorithm. The first step is to establish the model of direct georeference position using the data provided by the Po- sitioning and Orientation System (POS) and obtain the mathematical relationships between the image points and ground reference points. The second step is to apply polynomial distortion model and Bilinear Interpolation to get the final precise rectified images. In this step, a reference image is required and some ground control points (GCPs) are selected. Experiments showed that the final rectified images are satisfactory, and that our two-step rectification algorithm is very effective.展开更多
This paper starts with untime-diversification of the time-diversification deformation model and gives displacement distribution model of untime-diversification and simplifies further the study of deformation model. Th...This paper starts with untime-diversification of the time-diversification deformation model and gives displacement distribution model of untime-diversification and simplifies further the study of deformation model. The paper discusses the problem of least squares fitting of coordinate parameters model—parameters of deformation model. During discussion, the basic means of cubic B splines and two steps of multidimensional disorder datum fitting are adopted which can make fitting function calculated mostly approximate coordinate parameters model and it can make calculation easier.展开更多
LCL并网逆变器在采用基于事件触发机制的模型预测控制时,存在数控延迟及系统稳态性能易受运行工况变化影响等问题。为此,提出一种自适应事件触发的两步模型预测控制(adaptive event-triggered model predictive control with 2 steps,AE...LCL并网逆变器在采用基于事件触发机制的模型预测控制时,存在数控延迟及系统稳态性能易受运行工况变化影响等问题。为此,提出一种自适应事件触发的两步模型预测控制(adaptive event-triggered model predictive control with 2 steps,AET-MPC-2S)策略。首先,在模型预测控制环节中,该控制策略通过结合事件触发机制,筛选出合适的开关矢量进行两步预测;其次,AET-MPC引入自适应变量来监测系统的运行状态,对事件触发条件进行实时调节;最后,通过Matlab仿真和RT-LAB半实物平台进行验证。结果表明:AET-MPC-2S能够在实现延迟补偿的同时,减少两步预测的计算量,且不影响电流的跟踪效果,并能在运行工况发生变化后实时调节事件触发条件,使系统保持较好的稳态性能。论文研究可为降低LCL并网逆变器的开关频率以及改善系统的稳态性能提供参考。展开更多
基金supported by the Mathematics and Physics Foundation of Beijing Polytechnic University and the National Natural Science Foundation of China (Grant No 40536029)
文摘Explicit solutions are derived for some nonlinear physical model equations by using a delicate way of two-step ansatz method.
基金Project (No. 02CDP036) supported by the Royal Netherlands Academy of Arts and Sciences (KNAW), the Netherlands
文摘For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating curves are combined with the HEC-6 model to investigate the effects of river engineering measures on the Elbe River system. In such situations, the uncertainty originating from the HEC-6 model is of significant importance for the reliability of the rating curves and the corresponding DSS results. This paper proposes a two-step approach to analyze the uncertainty in the rating curves and propagate it into the Elbe DSS: analytic method and Latin Hypercube simulation. Via this approach the uncertainty and sensitivity of model outputs to input parameters are successfully investigated. The results show that the proposed approach is very efficient in investigating the effect of uncertainty and can play an important role in improving decision-making under uncertainty.
基金Project (No. 02DZ15001) supported by Shanghai Science and Technology Development Funds, China
文摘Rectification for airborne linear images is an indispensable preprocessing step. This paper presents in detail a two-step rectification algorithm. The first step is to establish the model of direct georeference position using the data provided by the Po- sitioning and Orientation System (POS) and obtain the mathematical relationships between the image points and ground reference points. The second step is to apply polynomial distortion model and Bilinear Interpolation to get the final precise rectified images. In this step, a reference image is required and some ground control points (GCPs) are selected. Experiments showed that the final rectified images are satisfactory, and that our two-step rectification algorithm is very effective.
文摘This paper starts with untime-diversification of the time-diversification deformation model and gives displacement distribution model of untime-diversification and simplifies further the study of deformation model. The paper discusses the problem of least squares fitting of coordinate parameters model—parameters of deformation model. During discussion, the basic means of cubic B splines and two steps of multidimensional disorder datum fitting are adopted which can make fitting function calculated mostly approximate coordinate parameters model and it can make calculation easier.
文摘LCL并网逆变器在采用基于事件触发机制的模型预测控制时,存在数控延迟及系统稳态性能易受运行工况变化影响等问题。为此,提出一种自适应事件触发的两步模型预测控制(adaptive event-triggered model predictive control with 2 steps,AET-MPC-2S)策略。首先,在模型预测控制环节中,该控制策略通过结合事件触发机制,筛选出合适的开关矢量进行两步预测;其次,AET-MPC引入自适应变量来监测系统的运行状态,对事件触发条件进行实时调节;最后,通过Matlab仿真和RT-LAB半实物平台进行验证。结果表明:AET-MPC-2S能够在实现延迟补偿的同时,减少两步预测的计算量,且不影响电流的跟踪效果,并能在运行工况发生变化后实时调节事件触发条件,使系统保持较好的稳态性能。论文研究可为降低LCL并网逆变器的开关频率以及改善系统的稳态性能提供参考。
