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Searching for an Optimized Single-objective Function Matching Multiple Objectives with Automatic Calibration of Hydrological Models
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作者 TIAN Fuqiang HU Hongchang +2 位作者 SUN Yu LI Hongyi LU Hui 《Chinese Geographical Science》 SCIE CSCD 2019年第6期934-948,共15页
In the calibration of hydrological models, evaluation criteria are explicitly and quantitatively defined as single-or multi-objective functions when utilizing automatic calibration approaches.In most previous studies,... In the calibration of hydrological models, evaluation criteria are explicitly and quantitatively defined as single-or multi-objective functions when utilizing automatic calibration approaches.In most previous studies, there is a general opinion that no single-objective function can represent all important characteristics of even one specific hydrological variable(e.g., streamflow).Thus hydrologists must turn to multi-objective calibration.In this study, we demonstrated that an optimized single-objective function can compromise multi-response modes(i.e., multi-objective functions) of the hydrograph, which is defined as summation of a power function of the absolute error between observed and simulated streamflow with the exponent of power function optimized for specific watersheds.The new objective function was applied to 196 model parameter estimation experiment(MOPEX) watersheds across the eastern United States using the semi-distributed Xinanjiang hydrological model.The optimized exponent value for each watershed was obtained by targeting four popular objective functions focusing on peak flows, low flows, water balance, and flashiness, respectively.Results showed that the optimized single-objective function can achieve a better hydrograph simulation compared to the traditional single-objective function Nash-Sutcliffe efficiency coefficient for most watersheds, and balance high flow part and low flow part of the hydrograph without substantial differences compared to multi-objective calibration.The proposed optimal single-objective function can be practically adopted in the hydrological modeling if the optimal exponent value could be determined a priori according to hydrological/climatic/landscape characteristics in a specific watershed. 展开更多
关键词 automatic calibration single-objective function MULTI-objective functions Xinanjiang model HYDROLOGICAL model
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A Sound Quality Objective Evaluation Method Based on Auditory Peripheral Simulation Model 被引量:1
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作者 Yinhan Gao~1,Jun Xie~2,Jie Liang~1,Xin Chang~3,Baojun Wu~2 1.Experimental Centre of Testing Science,Jilin University,Changchun 130022,P.R.China 2.College of Instrumentation & Electrical Engineering,Jilin University,Changchun 130061,P.R.China 3.Laboratory of Applications and Computations in Electromagnetics and Optics,Department of Electrical Engineering, University of Washington,WA 98195-2500,USA 《Journal of Bionic Engineering》 SCIE EI CSCD 2010年第2期199-208,共10页
Based on auditory peripheral simulation model, a new Sound Quality Objective Evaluation (SQOE) method is presented,which can be used to model and analyze the impacts of head, shoulder and other parts of human body on ... Based on auditory peripheral simulation model, a new Sound Quality Objective Evaluation (SQOE) method is presented,which can be used to model and analyze the impacts of head, shoulder and other parts of human body on sound wave trans-mission.This method employs the artificial head technique, in which the head related transfer function was taken into account tothe outer ear simulation phase.First, a bionic artificial head was designed as the outer ear model with considering the outersound field in view of theory and physical explanations.Then the auditory peripheral simulation model was built, which mimicsthe physiological functions of the human hearing, simulating the acoustic signal transfer process and conversion mechanismsfrom the free field to the peripheral auditory system.Finally, performance comparison was made between the proposed SQOEmethod and ArtemiS software, and the verifications of subjective and objective related analysis were made.Results show thatthe proposed method was economical, simple, and with good evaluation quality. 展开更多
关键词 sound quality objective evaluation auditory peripheral simulation model artificial head head related transfer function
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Performance Monitoring of the Data-driven Subspace Predictive Control Systems Based on Historical Objective Function Benchmark 被引量:3
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作者 王陆 李柠 李少远 《自动化学报》 EI CSCD 北大核心 2013年第5期542-547,共6页
关键词 预测控制系统 性能监控 数据驱动 子空间 历史 基准 监视控制器 目标函数
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A Distributed Strategy for Defensing Objective Function Attack in Large-scale Cognitive Networks
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作者 Guangsheng Feng Junyu Lin +3 位作者 Huiqiang Wang Xiaoyu Zhao Hongwu Lv Qiao Zhao 《国际计算机前沿大会会议论文集》 2015年第1期4-5,共2页
Most of existed strategies for defending OFA (Objective Function Attack)are centralized, only suitable for small-scale networks and stressed on the computation complexity and traffic load are usually neglected. In thi... Most of existed strategies for defending OFA (Objective Function Attack)are centralized, only suitable for small-scale networks and stressed on the computation complexity and traffic load are usually neglected. In this paper, we pay more attentions on the OFA problem in large-scale cognitive networks, where the big data generated from the network must be considered and the traditional methods could be of helplessness. In this paper, we first analyze the interactive processes between attacker and defender in detail, and then a defense strategy for OFA based on differential game is proposed, abbreviated as DSDG. Secondly, the game saddle point and optimal defense strategy have proved to be existed simultaneously. Simulation results show that the proposed DSDG has a less influence on network performance and a lower rate of packet loss.More importantly, it can cope with the large range 展开更多
关键词 COGNITIVE NETWORKS objective function ATTACK GAME model
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Object-Oriented Modeling of the Variation of Acceleration and Deceleration Characteristics in Relation to Speed Bands for Railway Vehicles
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作者 Hyun-Soo Jeong Jong-Young Park Hanmin Lee 《Energy and Power Engineering》 2023年第8期277-290,共14页
Automated operation and artificial intelligence technology have become essential for ensuring the safety, efficiency, and punctuality of railways, with applications such as ATO (Automatic Train Operation). In this stu... Automated operation and artificial intelligence technology have become essential for ensuring the safety, efficiency, and punctuality of railways, with applications such as ATO (Automatic Train Operation). In this study, the authors propose a method to efficiently simulate the kinematic characteristics of railroad vehicles depending on their speed zone. They utilized the function overloading function supported by a programming language and applied the fourth-order Lunge-Kutta method for dynamic simulation. By constructing an object model, the authors calculated vehicle characteristics and TPS and compared them with actual values, verifying that the developed model represents the real-life vehicle characteristics accurately. The study highlights potential improvements in automated driving and energy consumption optimization in the railway industry. 展开更多
关键词 Railway Vehicle ATO Lunge-Kutta Method object-Oriented model function Overloading
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Dynamic finite element model updating of prestressed concrete continuous box-girder bridge 被引量:6
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作者 Lin Xiankun Zhang Lingmi +1 位作者 Guo Qintao Zhang Yufeng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第3期399-407,共9页
The dynamic finite element model (FEM) of a prestressed concrete continuous box-girder bridge, called the Tongyang Canal Bridge, is built and updated based on the results of ambient vibration testing (AVT) using a... The dynamic finite element model (FEM) of a prestressed concrete continuous box-girder bridge, called the Tongyang Canal Bridge, is built and updated based on the results of ambient vibration testing (AVT) using a real-coded accelerating genetic algorithm (RAGA). The objective functions are defined based on natural frequency and modal assurance criterion (MAC) metrics to evaluate the updated FEM. Two objective functions are defined to fully account for the relative errors and standard deviations of the natural frequencies and MAC between the AVT results and the updated FEM predictions. The dynamically updated FEM of the bridge can better represent its structural dynamics and serve as a baseline in long-term health monitoring, condition assessment and damage identification over the service life of the bridge . 展开更多
关键词 prestressed concrete continuous box-girder bridge field ambient vibration testing dynamic characteristics model updating accelerating genetic algorithm objective function
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Hierarchical model updating strategy of complex assembled structures with uncorrelated dynamic modes 被引量:4
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作者 Chengwei FEI Haotian LIU +2 位作者 Rhea PATRICIA LIEM Yatsze CHOY Lei HAN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第3期281-296,共16页
In structural simulation and design,an accurate computational model directly determines the effectiveness of performance evaluation.To establish a high-fidelity dynamic model of a complex assembled structure,a Hierarc... In structural simulation and design,an accurate computational model directly determines the effectiveness of performance evaluation.To establish a high-fidelity dynamic model of a complex assembled structure,a Hierarchical Model Updating Strategy(HMUS)is developed for Finite Element(FE)model updating with regard to uncorrelated modes.The principle of HMUS is first elaborated by integrating hierarchical modeling concept,model updating technology with proper uncorrelated mode treatment,and parametric modeling.In the developed strategy,the correct correlated mode pairs amongst the uncorrelated modes are identified by an error minimization procedure.The proposed updating technique is validated by the dynamic FE model updating of a simple fixed–fixed beam.The proposed HMUS is then applied to the FE model updating of an aeroengine stator system(casings)to demonstrate its effectiveness.Our studies reveal that(A)parametric modeling technique is able to build an efficient equivalent model by simplifying complex structure in geometry while ensuring the consistency of mechanical characteristics;(B)the developed model updating technique efficiently processes the uncorrelated modes and precisely identifies correct Correlated Mode Pairs(CMPs)between FE model and experiment;(C)the proposed HMUS is accurate and efficient in the FE model updating of complex assembled structures such as aeroengine casings with large-scale model,complex geometry,high-nonlinearity and numerous parameters;(D)it is appropriate to update a complex structural FE model parameterized.The efforts of this study provide an efficient updating strategy for the dynamic model updating of complex assembled structures with experimental test data,which is promising to promote the precision and feasibility of simulation-based design optimization and performance evaluation of complex structures. 展开更多
关键词 Aeroengine casings Assembled structures Correlated mode pair Hierarchical model updating objective function Uncorrelated modes
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On the Consortium for Business Object Promotion (CBOP)
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作者 Hajime Horiuchi Management Information,Tokyo International University, 1 13 1 Matobakita, kawagoe, Saitama 350\|1197, Japan 《Wuhan University Journal of Natural Sciences》 CAS 2001年第Z1期25-30,共6页
This paper deals with the goals and visions of a consortium in Japan, named Consortium for Business Object Promotion (CBOP), discussing its background, activities, and basic technical approaches to share and exchangin... This paper deals with the goals and visions of a consortium in Japan, named Consortium for Business Object Promotion (CBOP), discussing its background, activities, and basic technical approaches to share and exchanging various types of Business Objects. Especially, Object Pattern Technologies used in CBOP should be discussed. 展开更多
关键词 business object object pattern software framework software component business function object pattern (BFOP) object registry meta model framework
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Method for Visual Localization of Oil and Gas Wellhead Based on Distance Function of Projected Features
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作者 Ying Xie Xiang-Dong Yang +2 位作者 Zhi Liu Shu-Nan Ren Ken Chen 《International Journal of Automation and computing》 EI CSCD 2017年第2期147-158,共12页
A localization method based on distance function of projected features is presented to solve the accuracy reduction or failure problem due to occlusion and blurring caused by smog, when dealing with vision based local... A localization method based on distance function of projected features is presented to solve the accuracy reduction or failure problem due to occlusion and blurring caused by smog, when dealing with vision based localization for target oil and gas wellhead (OGWH). Firstly, the target OGWH is modeled as a cylinder with marker, and a vector with redundant parameter is used to describe its pose. Secondly, the explicit mapping relationship between the pose vector with redundant parameter and projected features is derived. Then, a 2D-point-to-feature distance function is proposed, as well as its derivative. Finally, based on this distance function and its derivative, an algorithm is proposed to estimate the pose of target OGWH directly according to the 2D image information, and the validity of the method is verified by both synthetic data and real image experiments. The results show that this method is able to accomplish the localization in the case of occlusion and blurring, and its anti-noise ability is good especially with noise ratio of less than 70%. 展开更多
关键词 Robot vision visual localization 3D object localization model based pose estimation distance function of projectedfeatures nonlinear least squares random sample consensus (RANSAC).
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Enhanced history matching process by incorporation of saturation logs as model selection criteria
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作者 APONTE Jesus Manuel WEBBER Robert +3 位作者 CENTENO Maria Astrid DHAKAL Hom Nath SAYED Mohamed Hassan MALAKOOTI Reza 《Petroleum Exploration and Development》 SCIE 2023年第2期450-463,共14页
This paper proposes a methodology for an alternative history matching process enhanced by the incorporation of a simplified binary interpretation of reservoir saturation logs(RST) as objective function. Incorporating ... This paper proposes a methodology for an alternative history matching process enhanced by the incorporation of a simplified binary interpretation of reservoir saturation logs(RST) as objective function. Incorporating fluids saturation logs during the history matching phase unlocks the possibility to adjust or select models that better represent the near wellbore waterfront movement, which is particularly important for uncertainty mitigation during future well interference assessments in water driven reservoirs. For the purposes of this study, a semi-synthetic open-source reservoir model was used as base case to evaluate the proposed methodology. The reservoir model represents a water driven, highly heterogenous sandstone reservoir from Namorado field in Brazil. To effectively compare the proposed methodology against the conventional methods, a commercial reservoir simulator was used in combination with a state-of-the-art benchmarking workflow based on the Big LoopTMapproach. A well-known group of binary metrics were evaluated to be used as the objective function, and the Matthew correlation coefficient(MCC) has been proved to offer the best results when using binary data from water saturation logs. History matching results obtained with the proposed methodology allowed the selection of a more reliable group of reservoir models,especially for cases with high heterogeneity. The methodology also offers additional information and understanding of sweep behaviour behind the well casing at specific production zones, thus revealing full model potential to define new wells and reservoir development opportunities. 展开更多
关键词 geological modeling reservoir model objective function binary classification history matching saturation logs
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Theoretical Study on Stochastic Modeling of Combined Gravity-Magnetic-Electric-Seismic Inversion and Its Application
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作者 YanHanjie YanHong +1 位作者 LiYunping ZhangXiaofeng 《Journal of China University of Geosciences》 SCIE CSCD 2003年第3期227-233,共7页
As gravity field, magnetic field, electric field and seismic wave field are all physical fields, their object function, reverse function and compound function are certainly infinite continuously differentiable functio... As gravity field, magnetic field, electric field and seismic wave field are all physical fields, their object function, reverse function and compound function are certainly infinite continuously differentiable functions which can be expanded into Taylor (Fourier) series within domain of definition and be further reduced into solving stochastic distribution function of series and statistic inference of optimal approximation. This is the basis of combined gravity-magnetic-electric-seismic inversion of stochastic modeling. It is an uncertainty modeling technology of combining gravity-magnetic-electric-seismic inversion built on the basis of separation of field and source gravity-magnetic difference-value (D-value) trend surface, taking distribution-independent fault system as its unit, depths of seismic and electric interfaces of interests as its corresponding bivariate compound reverse function of gravity-magnetic anomalies and using high order polynomial (high order trigonometric function) approximating to its series distribution. The difference from current dominant inversion techniques is that, first, it does not respectively create gravity-seismic, magnetic-seismic deterministic inversion model from theoretical model, but combines gravity-magnetic-electric-seismic stochastic inversion model from stochastic model; second, after the concept of equivalent geological body being introduced, using feature of independent variable of gravity-magnetic field functions, taking density and susceptibility related to gravity-magnetic function as default parameters of model, the deterministic model is established owing to better solution to the contradiction of difficulty in identifying strata and less test analytical data for density and susceptibility in newly explored area; third, under assumption of independent parent distribution, a real modeling by strata, the problem of difficult plane closure arising in profile modeling is avoided. This technology has richer and more detailed fault and strata information than sparse pattern seismic data in newly explored area, successfully inverses and plots structural map of Indosinian discontinuity in Hefei basin with combined gravity-magnetic-electric-seismic inversion. With development of high precision gravity-magnetic and overall geophysical technology, it is certain for introducing new methods of stochastic modeling and computational intelligence and promoting the development of combined gravity-magnetic-electric-seismic inversion to open a new substantial path. 展开更多
关键词 gravity-magnetic compound reverse function stochastic geological model probability statistics gravity-magnetic d-value trend surface analysis.
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Similarities of Model Predictive Control and Constrained Direct Inverse
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作者 László Richárd Tóth Lajos Nagy Ferenc Szeifert 《Intelligent Control and Automation》 2012年第3期278-283,共6页
To reach an acceptable controller strategy and tuning it is important to state what is considered “good”. To do so one can set up a closed-loop specification or formulate an optimal control problem. It is an interes... To reach an acceptable controller strategy and tuning it is important to state what is considered “good”. To do so one can set up a closed-loop specification or formulate an optimal control problem. It is an interesting question, if the two can be equivalent or not. In this article two controller strategies, model predictive control (MPC) and constrained direct inversion (CDI) are compared in controlling the model of a pilot-scale water heater. Simulation experiments show that the two methods are similar, if the manipulator movements are not punished much in MPC, and they act practically the same when a filtered reference signal is applied. Even if the same model is used, it is still important to choose tuning parameters appropriately to achieve similar results in both strategies. CDI uses an analytic approach, while MPC uses numeric optimization, thus CDI is more computationally efficient, and can be used either as a standalone controller or to supplement numeric optimization. 展开更多
关键词 model PREDICTIVE CONTROL INVERSE CONTROL objective function CLOSED-LOOP Specification Heat Transfer
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Estimation and analysis of vegetation parameters for the water cloud model
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作者 Xiangdong Qin Zhiguo Pang Jingxuan Lu 《River》 2024年第4期399-407,共9页
The Water Cloud Model(WCM)plays a crucial role in active microwave soil moisture inversion applications.Empirical parameters are important factors affecting the accuracy of WCM simulation,but the current evaluation of... The Water Cloud Model(WCM)plays a crucial role in active microwave soil moisture inversion applications.Empirical parameters are important factors affecting the accuracy of WCM simulation,but the current evaluation of empirical parameters only considers the forward simulation process,and insufficient consideration is given to the model inversion problem.This study proposes a new estimation method for vegetation parameters in the WCM by combining the soil backscattering model and the objective function.The effectiveness of the method is then verified using measured data.Simultaneously,this study also analyzes the factors influencing the evaluation of vegetation parameters in the WCM,resulting in the following conclusions.First,blindly utilizing vegetation parameters recommended by previous model studies is not advisable.To ensure the accuracy of the simulation,it is necessary to adjust the vegetation parameters appropriately.Second,to ensure the ability of the WCM solving both forward and inverse problems,it is advisable to consider both soil backscatter and surface backscatter simulations in the construction of the cost function.Third,soil backscatter simulations have an impact on the solution of vegetation parameters,and more accurate soil scattering models provide a better representation of the modeled vegetation.This study presents a dependable method for resolving the vegetation parameters of the WCM,thereby offering a valuable reference for the application of the model in surface parameter inversion research. 展开更多
关键词 backscattering coefficient gradient descent algorithm objective function soil moisture water cloud model
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基于改进蚁群算法的无线传感网络路由优化方法 被引量:3
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作者 李忠 严莉 +1 位作者 倪建军 汤嘉立 《计算机与网络》 2025年第1期67-75,共9页
为了提高传统无线传感网络路由的性能,提出基于改进蚁群算法的无线传感网络路由优化方法,包括路由控制层、SDN信息收集层和数据转发层。借助参考节点和锚节点确定未知节点位置,并根据节点位置设计优化目标函数。通过改进蚁群算法中的转... 为了提高传统无线传感网络路由的性能,提出基于改进蚁群算法的无线传感网络路由优化方法,包括路由控制层、SDN信息收集层和数据转发层。借助参考节点和锚节点确定未知节点位置,并根据节点位置设计优化目标函数。通过改进蚁群算法中的转移概率和信息素浓度,求解目标函数,获得最佳的路由方案。实验结果表明,该方法在能量消耗、传输时延、死亡节点数量和网络吞吐量等方面均有明显改善,有效提高了无线传感网络路由的性能。 展开更多
关键词 改进蚁群算法 无线传感网络 路由优化 路由模型 目标函数
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基于不同目标函数的WRF-Hydro模型参数敏感性研究 被引量:1
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作者 谷黄河 石怀轩 +2 位作者 孙敏涛 丁震 顾苏烨 《中国农村水利水电》 北大核心 2025年第1期61-69,共9页
水文与气象预报相结合可以有效提高洪水预报的精度和延长预见期,陆气耦合模型已成为水文气象学者研究的重点。WRF-Hydro模型作为新一代分布式陆气耦合模型在多尺度洪水预报中具有广阔的应用前景,但由于各物理过程参数化方案复杂,模型计... 水文与气象预报相结合可以有效提高洪水预报的精度和延长预见期,陆气耦合模型已成为水文气象学者研究的重点。WRF-Hydro模型作为新一代分布式陆气耦合模型在多尺度洪水预报中具有广阔的应用前景,但由于各物理过程参数化方案复杂,模型计算量大,对该模型的参数敏感性研究还不充分,也影响着模型的模拟精度。研究以湿润区的新安江上游屯溪流域为研究对象,构建多个单目标和多目标函数,并结合Morris全局参数敏感性分析方法,探究了WRF-Hydro模型在不同目标函数下的参数敏感性。结果表明:土壤参数(DKSAT、SMCMAX、BEXP)主要影响壤中流和地表径流,对径流量影响显著,尤其DKSAT最为敏感,直接影响水在土壤中的下渗速度,增大时基流量显著增高而洪峰流量则明显降低;产流参数(SLOPE、REFKDT)主要影响地表径流和基流分配,对洪水过程线形状有重要影响;河道汇流参数ManN影响汇流速度并主要控制峰现时间;植被参数MP对于总水量有一定影响;坡面汇流参数OVROUGHRTFAC和地下水参数Zmax则最不敏感。不同目标函数下的参数敏感性顺序和最优参数取值有一定差异,单目标函数中以相对误差为优化目标会更侧重于全年径流总量和低流量部分的模拟精度,而以效率系数和Kling-Gupta系数为目标则更侧重于场次洪水和高流量部分的模拟效果;基于几个单目标函数组合的多目标函数综合考虑了不同目标函数的影响,结果在一定程度上优于单目标函数。研究可为合理确定WRF-Hydro模型参数优化策略提供参考。 展开更多
关键词 WRF-Hydro模型 Morris法 敏感性分析 多目标函数 洪水预报
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开关电感准Z源逆变器无权重系数FCS-MPC策略
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作者 刘春喜 林枝伟 +1 位作者 刘志乐 徐可 《电机与控制学报》 北大核心 2025年第3期142-154,共13页
针对开关电感准Z源逆变器采用有限集模型预测控制(FCS-MPC)时目标函数权重系数设计复杂的问题,提出一种无权重系数的FCS-MPC算法,避免了繁琐的权重系数调整过程。通过伏秒平衡原理分析电感周期性充放电的机理,在直通状态时对电感电流设... 针对开关电感准Z源逆变器采用有限集模型预测控制(FCS-MPC)时目标函数权重系数设计复杂的问题,提出一种无权重系数的FCS-MPC算法,避免了繁琐的权重系数调整过程。通过伏秒平衡原理分析电感周期性充放电的机理,在直通状态时对电感电流设置一个中间值,根据中间值和预测值的比较来确定下一周期的开关状态,在非直通状态时则采用归一化思想将输出电流和电容电压的目标函数设计为基于动态变化的函数,将误差限制在[0,1]范围内,从而不需要任何权重系数,避免了权重系数的调整过程,最后通过仿真和实验对所提的方法进行验证。结果表明:所提无权重系数FCS-MPC策略与传统FCS-MPC策略相比,在无权重系数的情况下,系统的稳态性能相同,动态性能更优。 展开更多
关键词 开关电感准Z源逆变器 有限集模型预测控制 无权重系数 目标函数 伏秒平衡 归一化
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基于FCLPSO的水量水质模型参数反演方法研究
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作者 朱沈涛 杨帆 +3 位作者 柳杨 范子武 乌景秀 李子祥 《水利水电技术(中英文)》 北大核心 2025年第7期54-66,共13页
【目的】复杂河网水量水质模型中参数多、维数高,模型参数反演难度大,优化目标函数选取、单参数和多参数不同反演方式等对参数反演精度影响需开展深入分析。【方法】提出基于快速综合粒子群优化算法(Fast Comprehensive Learning Partic... 【目的】复杂河网水量水质模型中参数多、维数高,模型参数反演难度大,优化目标函数选取、单参数和多参数不同反演方式等对参数反演精度影响需开展深入分析。【方法】提出基于快速综合粒子群优化算法(Fast Comprehensive Learning Particle Swarm Optimization,FCLPSO)的水量水质模型参数反演方法,设计参数反演数值试验,采用LH-OAT全局敏感性分析方法对7种模型性能评价指标进行目标函数优选,并分析模型单参数和多参数反演结果并分析不同反演方式的差异性。【结果】结果显示:NSE∗作为目标函数敏感度最高;不同类型参数均具有较高精度,单参数反演平均相对误差(MRE)为5.2%、变差系数(CV)为7.2%,多参数反演结果MRE为13.5%、CV为14%;多参数反演中水动力指标反演结果优于水质指标反演结果,多参数“分层反演”方式优于“同时反演”方式。【结论】结果表明:该模型参数反演方法具有较高的精度,有助于提升复杂河网水量水质模型参数估计时效性与准确性,为复杂河网数值模拟精度的提升提供了技术支撑。 展开更多
关键词 水量水质模型 参数反演 快速综合粒子群优化算法 目标函数 敏感性分析
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4/2模型下目标给付型养老金计划的最优投资和给付策略
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作者 韩婧怡 常浩 陈祯 《山东大学学报(理学版)》 北大核心 2025年第3期49-59,共11页
4/2随机波动率下的目标给付型养老金(target benefit pension,TBP)计划包含在职成员和退休成员,在职成员向养老基金缴纳固定费用,退休成员从基金中领取相应养老金,退休成员的给付水平取决于基金的投资情况。假设养老金可以投资于一种无... 4/2随机波动率下的目标给付型养老金(target benefit pension,TBP)计划包含在职成员和退休成员,在职成员向养老基金缴纳固定费用,退休成员从基金中领取相应养老金,退休成员的给付水平取决于基金的投资情况。假设养老金可以投资于一种无风险资产和一种股票,股票的价格过程遵循4/2随机波动率模型。运用随机最优控制理论,得到最优投资和给付调整策略的显式解,应用数值算例分析各模型参数对最优投资和给付调整策略的影响。该研究为随机波动率模型下的其他复杂投资问题的解决提供方法论基础,也为基金管理者的资产配置和风险管理提供参考依据。 展开更多
关键词 目标给付型养老金计划 4/2随机波动率模型 偏差型目标函数 随机最优控制理论
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红松人工林多目标经营模型
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作者 李爽 蒋博 +1 位作者 金星姬 PUKKALA Timo 《南京林业大学学报(自然科学版)》 北大核心 2025年第6期55-63,共9页
【目的】以下层伐为约束条件,通过优化不同立地指数下红松(Pinus koraiensis)人工林的经营措施和构建经营模型,指导红松人工林的多目标经营并制订黑龙江省红松人工林多目标经营方案,提高我国人工林多目标经营水平。【方法】利用多属性... 【目的】以下层伐为约束条件,通过优化不同立地指数下红松(Pinus koraiensis)人工林的经营措施和构建经营模型,指导红松人工林的多目标经营并制订黑龙江省红松人工林多目标经营方案,提高我国人工林多目标经营水平。【方法】利用多属性效用函数构建以林分木材产量(WP)、大径材产量(LLP)和球果产量(CY)同时最大为经营目标的多目标方程WP、LLP、CY,3个经营目标的权重分别为:0.25、0.25、0.50。组合林分生长模拟器和差分进化算法,优化求解黑龙江省41块红松人工幼龄林样地的最佳采伐措施。以林分变量作为预测变量,构建采伐时林分密度、不同径阶的采伐强度(由logistic函数参数描述,该参数指示间伐强度为50%时的林分平均胸径)、主伐时林分平均胸径3个模型。【结果】最佳间伐时林分密度与平均胸径呈明显负相关,与立地指数呈正相关;logistic函数参数与平均胸径和立地指数呈正相关;主伐时林分平均胸径与立地指数呈正相关,与林分密度呈负相关。采伐时林分密度、采伐强度、主伐时林分平均胸径3个模型的校正后决定系数(R2a)分别为0.930、0.798和0.965,平均偏差(ME)分别为2.000株/hm^(2)、-0.015和0.128 cm,平均绝对误差(MAE)分别为91.000株/hm^(2)、1.238和0.165 cm。【结论】采伐时林分密度与地位指数呈正相关,与平均胸径呈负相关;间伐时林分平均胸径随地位指数的增加而增加;主伐时立地较差的林分比立地较好的林分平均胸径更小。 展开更多
关键词 红松人工林 多目标经营模型 经营准则 逻辑斯蒂函数 差分进化
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三维波动方程地震面波频散谱反演
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作者 张振东 刘伊克 《地球物理学报》 北大核心 2025年第9期3541-3553,共13页
地震面波反演是地球内部速度结构成像的重要方法,可用于壳幔、油气藏、城市地下空间等跨尺度目标成像.目前常用的一维面波频散曲线反演方法假设地下为层状介质、需要拾取频散曲线,不适合复杂构造地区的大规模地震面波成像;最新的面波波... 地震面波反演是地球内部速度结构成像的重要方法,可用于壳幔、油气藏、城市地下空间等跨尺度目标成像.目前常用的一维面波频散曲线反演方法假设地下为层状介质、需要拾取频散曲线,不适合复杂构造地区的大规模地震面波成像;最新的面波波形反演方法具有强非线性,对数据质量和初始速度模型精度等要求较高,在处理实际数据时还存在诸多问题.本文结合传统一维面波频散曲线反演方法和地震全波形反演理论的优势提出了三维波动方程面波频散谱反演方法,通过求解弹性波波动方程模拟地震面波在任意复杂介质中的传播过程;将复杂的地震面波波形变换到保留其频散特征的频率-相慢度谱域进行相似度比较,极大地降低了反演的非线性.借助全波形反演的统一理论框架,使用伴随状态法计算速度模型梯度和局部优化算法迭代更新速度模型.本文提出的频散谱反演方法适用于三维任意复杂介质的速度结构成像,模拟算例表明该方法具有比拟波形反演方法的空间分辨率;在美国亚利桑那州西南沙漠实测地震数据中的应用表明该方法可用于实际资料的处理.随着油气、地热、二氧化碳封存等陆地勘探目标的涌现,该方法有望为陆地探区高精度速度建模提供一种新的解决方案. 展开更多
关键词 面波 近地表成像 弹性波全波形反演 三维速度建模 目标函数
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