Large biases exist in real-time ENSO prediction, which can be attributed to uncertainties in initial conditions and model parameters. Previously, a 4D variational （4D-Vat） data assimilation system was developed for ...Large biases exist in real-time ENSO prediction, which can be attributed to uncertainties in initial conditions and model parameters. Previously, a 4D variational （4D-Vat） data assimilation system was developed for an intermediate coupled model （ICM） and used to improve ENSO modeling through optimized initial conditions. In this paper, this system is further applied to optimize model parameters. In the ICM used, one important process for ENSO is related to the anomalous temperature of subsurface water entrained into the mixed layer （Te）, which is empirically and explicitly related to sea level （SL） variation. The strength of the thermocline effect on SST （referred to simply as ＂the thermocline effect＂） is represented by an introduced parameter, （l＇Te. A numerical procedure is developed to optimize this model parameter through the 4D-Var assimilation of SST data in a twin experiment context with an idealized setting. Experiments having their initial condition optimized only, and having their initial condition plus this additional model parameter optimized, are compared. It is shown that ENSO evolution can be more effectively recovered by including the additional optimization of this parameter in ENSO modeling. The demonstrated feasibility of optimizing model parameters and initial conditions together through the 4D-Var method provides a modeling platform for ENSO studies. Further applications of the 4D-Vat data assimilation system implemented in the ICM are also discussed.展开更多
Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational implementation.The incremental 4D-VAR assi...Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational implementation.The incremental 4D-VAR assimilation scheme is set up in order to reduce the computational cost. It is shown that the accuracy of the observations, the length of the assimilation window and the choice of the first guess have an important influence on the assimilation outcome through the contrast experiment. Compared with the standard 4D-VAR assimilation scheme, the incremental 4D-VAR assimilation scheme shows its advantage in the computation speed through an assimilation experiment.展开更多
The AEC (Architecture, Engineering, and Construction) industry is gradually shifting away from 2D CAD drawings and toward Building Information Modeling as a result of the fast development of science and technology (BI...The AEC (Architecture, Engineering, and Construction) industry is gradually shifting away from 2D CAD drawings and toward Building Information Modeling as a result of the fast development of science and technology (BIM). The BIM idea’s introduction emphasizes the need to specify a building in a single building model with adequate information to suit its different needs rather than defining it in fragmented documents. This research work aims to use the BIM 4D for the simulation of the construction sequence of a Swivel Bridge. For that, the software Revit was used to make the 3D model of the bridge, and the software Navisworks was used for the 4D construction simulation of the project. The results demonstrated that BIM technology could help reduce delays and problems with the schedule and improve communication among stakeholders, and BIM visualization and simulation features were very useful compared to traditional planning methods.展开更多
4D技术的发展和应用给建设项目带来了巨大的效益,但目前用于4D模拟的3D模型一般在施工前创建,4D模拟的应用局限于施工前的计划阶段。为将4D模拟的应用扩展至项目施工阶段,对4D模拟的3D模型进行研究,着重对比分析施工模型和实时施工模型...4D技术的发展和应用给建设项目带来了巨大的效益,但目前用于4D模拟的3D模型一般在施工前创建,4D模拟的应用局限于施工前的计划阶段。为将4D模拟的应用扩展至项目施工阶段,对4D模拟的3D模型进行研究,着重对比分析施工模型和实时施工模型,研究BIM(Building Information Modeling,建筑信息模型)模型的自动创建技术。研究发现,自动化创建的BIM实时施工模型可以动态的跟踪项目进展情况,能提高模型的准确性和减少建模工作量。提出基于BIM实时施工模型的4D模拟,是一个动态的4D模拟过程,可作为项目施工全过程的动态控制的有效工具,能进一步提高建设项目的效率和效益。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41705082, 41475101, 41690122(41690120))a Chinese Academy of Sciences Strategic Priority Project-the Western Pacific Ocean System (Grant Nos. XDA11010105 and XDA11020306)+1 种基金the National Programme on Global Change and Air–Sea Interaction (Grant Nos. GASI-IPOVAI06 and GASI-IPOVAI-01-01)the China Postdoctoral Science Foundation, and a Qingdao Postdoctoral Application Research Project
文摘Large biases exist in real-time ENSO prediction, which can be attributed to uncertainties in initial conditions and model parameters. Previously, a 4D variational （4D-Vat） data assimilation system was developed for an intermediate coupled model （ICM） and used to improve ENSO modeling through optimized initial conditions. In this paper, this system is further applied to optimize model parameters. In the ICM used, one important process for ENSO is related to the anomalous temperature of subsurface water entrained into the mixed layer （Te）, which is empirically and explicitly related to sea level （SL） variation. The strength of the thermocline effect on SST （referred to simply as ＂the thermocline effect＂） is represented by an introduced parameter, （l＇Te. A numerical procedure is developed to optimize this model parameter through the 4D-Var assimilation of SST data in a twin experiment context with an idealized setting. Experiments having their initial condition optimized only, and having their initial condition plus this additional model parameter optimized, are compared. It is shown that ENSO evolution can be more effectively recovered by including the additional optimization of this parameter in ENSO modeling. The demonstrated feasibility of optimizing model parameters and initial conditions together through the 4D-Var method provides a modeling platform for ENSO studies. Further applications of the 4D-Vat data assimilation system implemented in the ICM are also discussed.
基金the National Basic Research Program of China under Natural contract Nos 2007CB816001 and 2006CB400603Natinal Natural Science Foundation of China under contract Nos 40346027 and 40676008the China"908"-Project under Grant No.908-02-01-03 and 908-IC-I-13
文摘Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational implementation.The incremental 4D-VAR assimilation scheme is set up in order to reduce the computational cost. It is shown that the accuracy of the observations, the length of the assimilation window and the choice of the first guess have an important influence on the assimilation outcome through the contrast experiment. Compared with the standard 4D-VAR assimilation scheme, the incremental 4D-VAR assimilation scheme shows its advantage in the computation speed through an assimilation experiment.
文摘The AEC (Architecture, Engineering, and Construction) industry is gradually shifting away from 2D CAD drawings and toward Building Information Modeling as a result of the fast development of science and technology (BIM). The BIM idea’s introduction emphasizes the need to specify a building in a single building model with adequate information to suit its different needs rather than defining it in fragmented documents. This research work aims to use the BIM 4D for the simulation of the construction sequence of a Swivel Bridge. For that, the software Revit was used to make the 3D model of the bridge, and the software Navisworks was used for the 4D construction simulation of the project. The results demonstrated that BIM technology could help reduce delays and problems with the schedule and improve communication among stakeholders, and BIM visualization and simulation features were very useful compared to traditional planning methods.
文摘4D技术的发展和应用给建设项目带来了巨大的效益,但目前用于4D模拟的3D模型一般在施工前创建,4D模拟的应用局限于施工前的计划阶段。为将4D模拟的应用扩展至项目施工阶段,对4D模拟的3D模型进行研究,着重对比分析施工模型和实时施工模型,研究BIM(Building Information Modeling,建筑信息模型)模型的自动创建技术。研究发现,自动化创建的BIM实时施工模型可以动态的跟踪项目进展情况,能提高模型的准确性和减少建模工作量。提出基于BIM实时施工模型的4D模拟,是一个动态的4D模拟过程,可作为项目施工全过程的动态控制的有效工具,能进一步提高建设项目的效率和效益。
