检索结果-内蒙古大学图书馆

lumped-parameter models for low-temperature geothermal fields and their application

GEOTHERMICS 2005年第6期34卷 728-755页

作者： Sarak, H Onur, M Satman, A Istanbul Tech Univ Petr & Nat Gas Engn Dept TR-34469 Istanbul Turkey

The behavior of low-ternperature geothermal reservoirs under exploitation is simulated using analytical lurnped-parameter models. These models consider the effects of fluid production and reinjection, as well as natural recharge, on the pressures (or water levels) of low-temperature, liquid-dominated geothermal systems. The cornputed responses for constant production/injection flow rates are given in the form of analytical expressions. Variable flow rate cases are modeled, based on the Duharnel's principle. Reservoir parameters are obtained by applying a weighted nonlinear least-squares estimation technique in which measured field data are history matched to the corresponding model response. By using history-matched models, the future performance of the reservoir can be predicted for different production/injection scenarios in order to optimize the management of a given geothermal system. We demonstrate the applicability of the models by stimulating measured data from the Laugarnes geothermal field in Iceland, and the Balcova-Narlidere field in Turkey. (c) 2005 CNR. Published by Elsevier Ltd. All rights reserved.

关键词： geothermal reservoirs lumped-parameter models analytical solutions nonlinear parameter estimation predictions Laugarnes Balcova-Narlidere

来源：评论

学校读者我要写书评

暂无评论

Assessment of uncertainty in future performance predictions by lumped-parameter models for single-phase liquid geothermal systems

引用

GEOTHERMICS 2014年 51卷 300-311页

作者： Tureyen, Omer Inanc Kirmaci, Ayse Onur, Mustafa Istanbul Tech Univ Dept Petr & Nat Gas Engn TR-34469 Istanbul Turkey

A stochastic simulation methodology is presented for assessing the uncertainty in future pressure and/or temperature data simulated by using history-matched lumped-parameter models for single-phase liquid water geothermal systems. The methodology consists of a two-step procedure;first selecting the appropriate lumped-parameter model that can best describe the geothermal system based on history matching observed pressure and/or temperature datasets and then using a randomized maximum likelihood (RML) like method for the assessment of uncertainty. Any uncertainties in both the model and the measured data may be incorporated into the future performance predictions for the pressure. Once the uncertainty in predicted performance is characterized and assessed, it becomes possible to make reservoir management decisions that account for an incomplete knowledge of the actual geothermal system. One synthetic application and one field application from the Balcova-Narlidere geothermal field in Izmir, Turkey are presented to illustrate the methodology. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Geothermal lumped-parameter models Isothermal Non-isothermal History matching Production data Randomized maximum likelihood Uncertainty prediction

来源：评论

学校读者我要写书评

暂无评论

Dynamic response of vehicle-bridge-soil system using lumped-parameter models for structure-soil interaction

引用

COMPUTERS & STRUCTURES 2020年 238卷 106270-106270页

作者： Bucinskas, Paulius Andersen, Lars Vabbersgaard Aarhus Univ Dept Engn Aarhus Denmark

Prediction of vibrations generated by railway traffic experiences an increasing interest, as new lines are being constructed and planned in many countries. The paper proposes a numerical model to analyse a coupled vehicle-bridge-soil system, taking into account the most important phenomena affecting the structure, while at the same time being comparatively computationally efficient. Such model is useful in the early design phases of a project, when analysing a range of possible configurations or conducting parametric analysis is required. A simplified vehicle model, nonlinear wheel-rail interaction, a bridge structure modelled using the finite-element method and a semi-analytical model for layered soil are all introduced in the model. A pure time-domain solution procedure is used, utilizing lumped-parameter models (LPMs) for the soil-foundation system. Representation of the dynamic stiffness matrix using LPMs is investigated by analysing the cross-coupling between footings and a novel procedure necessary for computationally stable LPMs is introduced and utilized. Further, pure time-domain solution is compared with an iterative mixed-domain solution. Finally, to illustrate the capabilities of the model, analyses are carried out to determine the resulting maximum and minimum excitation limits resulting from wheel-rail interaction on a number of randomly generated uneven track profiles. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： High-speed railways Railway bridge Multi-degree-of-freedom vehicle Wheel-rail interaction Soil-structure interaction lumped-parameter models

来源：评论

学校读者我要写书评

暂无评论

Nonlinear lumped-parameter models for blood flow simulations in networks of vessels

引用

ESAIM-MATHEMATICAL MODELLING AND NUMERICAL ANALYSIS 2022年第5期56卷 1579-1627页

作者： Ghitti, Beatrice Toro, Eleuterio Francisco Muller, Lucas Omar Univ Trento Dept Math Trento Italy Univ Trento Lab Appl Math DICAM Trento Italy

To address the issue of computational efficiency related to the modelling of blood flow in complex networks, we derive a family of nonlinear lumped-parameter models for blood flow in compliant vessels departing from a well-established one-dimensional model. These 0D models must preserve important nonlinear properties of the original 1D model: the nonlinearity of the pressure-area relation and the pressure-dependent parameters characterizing the 0D models, the resistance R and the inductance L, defined in terms of a time-dependent cross-sectional area subject to pressure changes. We introduce suitable coupling conditions to join 0D vessels through 0D junctions and construct 0D networks preserving the original 1D network topology. The newly derived nonlinear 0D models are then applied to several arterial networks and the predicted results are compared against (i) the reference 1D results, to validate the models and assess their ability to reproduce good approximations of pressure and flow waveforms in all vessels at a much lower computational cost, measured in terms of CPU time, and (ii) the linear 0D results, to evaluate the improvement gained by including certain nonlinearities in the 0D models, in terms of agreement with the 1D results.

关键词： Blood flow lumped-parameter models nonlinearity coupling arterial networks

来源：评论

学校读者我要写书评

暂无评论

Machine learning for creation of generalized lumped parameter tank models of low temperature geothermal reservoir systems

引用

GEOTHERMICS 2017年 70卷 62-84页

作者： Li, Y. Juliusson, E. Palsson, H. Stefansson, H. Valfells, A. Tianjin Univ Key Lab Efficient Utilizat Low & Medium Grade Ene Minist Educ 92 Weijin Rd Tianjin 300072 Peoples R China Reykjavik Univ Sch Sci & Engn Menntavegi 1 IS-105 Reykjavik Iceland Landsvirkjun Haaleitisbraut 68 IS-103 Reykjavik Iceland Univ Iceland Fac Ind Engn Mech Engn & Comp Sci Hjardarhagi 2-6 IS-107 Reykjavik Iceland

lumped parameter tank models have gained renewed interest in recent years as an alternative tool for geothermal reservoir analysis and production planning. The models can be structured in various ways regarding the number of tanks, connections between the tanks and the parameters representing the physical properties of the geothermal system. It usually requires a time consuming and difficult process of trials and errors to manually decide the optimal configuration of a tank model. Inspired by recent development in the use of machine learning methods, we propose a method for automatically generating accurate and computationally feasible generalized tank models for isothermal, single phase, reservoirs. This is an extension of earlier work on complexity reduction of generalized tank models (Li et al., 2016). Here, a recursive "switch-back" method is constructed to maximize prediction accuracy of the model. It is also shown how the K-means clustering algorithm can be used to aggregate production wells in generalized tank models. One synthetic example and one field application from t Reykir geothermal fields in Iceland are used to illustrate the effectiveness of these methods.

关键词： Geothermal reservoir modeling lumped-parameter models Machine learning Complexity analysis Information criterion Complexity reduction algorithm Switch-back method Model selection K-means clustering algorithm

来源：评论

学校读者我要写书评

暂无评论

Monitoring variability in parameter estimates for lumped parameter models of the systemic circulation using longitudinal hemodynamic measurements

引用

BIOMEDICAL ENGINEERING ONLINE 2023年第1期22卷 1-35页

作者： Bjordalsbakke, Nikolai L. Sturdy, Jacob Ingestrom, Emma M. L. Hellevik, Leif R. Norwegian Univ Sci & Technol NTNU Dept Struct Engn Richard Birkelandsvei 1a Trondheim Norway Norwegian Univ Sci & Technol NTNU Dept Circulat & Med Imaging Prinsesse Kristinas Gt 3 Trondheim Norway

Background: Physics-based cardiovascular models are only recently being considered for disease diagnosis or prognosis in clinical settings. These models depend on parameters representing the physical and physiological properties of the modeled system. Personalizing these parameters may give insight into the specific state of the individual and etiology of disease. We applied a relatively fast model optimization scheme based on common local optimization methods to two model formulations of the left ventricle and systemic circulation. One closed-loop model and one open-loop model were applied. Intermittently collected hemodynamic data from an exercise motivation study were used to personalize these models for data from 25 participants. The hemodynamic data were collected for each participant at the start, middle and end of the trial. We constructed two data sets for the participants, both consisting of systolic and diastolic brachial pressure, stroke volume, and left-ventricular outflow tract velocity traces paired with either the finger arterial pressure waveform or the carotid pressure waveform. Results: We examined the feasibility of separating parameter estimates for the individual from population estimates by assessing the variability of estimates using the interquartile range. We found that the estimated parameter values were similar for the two model formulations, but that the systemic arterial compliance was significantly different (p < 10(-6)) depending on choice of pressure waveform. The estimates of systemic arterial compliance were on average higher when using the finger artery pressure waveform as compared to the carotid waveform. Conclusions: We found that for the majority of participants, the variability of param-eter estimates for a given participant on any measurement day was lower than the variability both across all measurement days combined for one participant, and for the population. This indicates that it is possible to identify individuals from

关键词： Cardiovascular modeling Model personalization lumped-parameter models parameter variability

来源：评论

学校读者我要写书评

暂无评论

Complexity Analysis of lumped parameter models: Development of Complexity Reduction Algorithm

Complexity Analysis of Lumped Parameter Models: Development ...

引用

作者： YUXI LI Reykjavik University

学位级别：硕士

lumped parameter models have been shown to be a useful tool for geothermal reservoir analysis and production planning. Tank models are a common form of lumped parameter models, incorporating tanks of given capacitance partially filled with fluid. Between the tanks are connections with given conductance, that allow fluid to flow between connected tanks with different fluid levels. In this thesis, we analyze how tank models of varying complexity compare in terms of accuracy and utility. An algorithm called Complexity Reduction Algorithm (CRA) is developed that automatically finds those models that are likely to be the best by choosing a certain path through the model space. Since in general, it is reasonable to expect that a complex model is able to give an accurate fitting result and the optimum model indicated by CRA only has a medium complexity, a switch-back method is developed to decrease the training error of the complex models. Also, in some cases, there is a large number of production wells that are producing hot water, which will lead to a situation where very many parameters needed to be estimated, since the number of parameters grows quadratically in terms of the number of tanks. The K-means clustering algorithm is shown to be suitable for finding an initial production tank configuration under such situations. Real data from the Laugarnes geothermal field and Reykir geothermal area in Iceland is shown in the thesis. The results show that the newly developed algorithm provides insights into model selection for lumped parameter models. The accuracy of both history-matched and predicted drawdown for lumped parameter models of varying complexity and the results by using the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) as an indicator for model selection have been shown.

关键词： Geothermal reservoir modeling lumped-parameter models Complexity analysis Information criterion Complexity Reduction Algorithm Switch-back method Model selection K-means clustering algorithm

来源：评论

学校读者我要写书评

暂无评论

Building a metamodel of an irrigation district distributed-parameter model

引用

AGRICULTURAL WATER MANAGEMENT 2010年第2期97卷 187-200页

作者： Galelli, S. Gandolfi, C. Soncini-Sessa, R. Agostani, D. Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy Univ Milan Dipartimento Ingn Agr I-20133 Milan Italy

Complex decision-making problems, related to planning and management of irrigation water resources, generally preclude the use of large, distributed-parameter models, which are then commonly substituted by lumped-parameter models. This paper, with the aim of improving the quality of these latter, introduces a new approach for their design. This approach is based on metamodelling, which proposes to identify a simple, lumped-parameter model on the basis of the data produced via simulation with a distributed-parameter model. The approach proposed is tested on a real-world case study, namely the identification of a metamodel describing the water demand of the Muzza-Bassa Lodigiana irrigation district (Italy). The metamodel, which inherits the physical description of the original distributed-parameter model, is sufficiently simple to permit the resolution of an optimal control problem, i.e. the design, via stochastic dynamic programming, of the release policy of Lake Como, serving the Muzza irrigation district. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Flood irrigation water management Distributed-parameter models lumped-parameter models Metamodels Green water Blue water

来源：评论

学校读者我要写书评

暂无评论

Simplified model for torsional foundation vibrations

引用

SOIL DYNAMICS AND EARTHQUAKE ENGINEERING 2007年第3期27卷 250-258页

作者： Chen, Shi-Shuenn Shi, Jun-Yang Natl Taiwan Univ Sci & Technol Dept Construct Engn Taipei 106 Taiwan

A simplified model is presented to simulate unbounded soil for torsional foundation vibration problems. Based on the criterion of equivalent displacement response, a group of equivalent models are developed for a foundation-soil system. An optimal equivalent model is then determined to represent the best simplified model. The parameters of the optimal equivalent model may be obtained by a much easier and more efficient method than lengthy optimization techniques used by most existing lumped-parameter models. The dynamic torsional responses of the foundation-soil system using the optimal equivalent models are very consistent with those obtained by the half-space theory and by the existing models. With fewer parameters, the optimal equivalent model is also found to be as accurate as most existing models. This proposed method may be effectively applied to practical torsionally vibrating problems involving soil-structure interaction. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： lumped-parameter models embedded foundation soil-structure interaction

来源：评论

学校读者我要写书评

暂无评论

Nonlinear stability analysis of a reduced order model of nuclear reactors: A parametric study relevant to the advanced heavy water reactor

引用

NUCLEAR ENGINEERING AND DESIGN 2011年第1期241卷 134-143页

作者： Wahi, Pankaj Kumawat, Vivek Indian Inst Technol Kanpur Dept Mech Engn Kanpur 208016 Uttar Pradesh India Indian Inst Technol Kanpur Nucl Engn & Technol Program Kanpur 208016 Uttar Pradesh India

In this paper, we perform a parametric study of the nonlinear dynamics of a reduced order model for boiling water reactors (BWR) near the Hopf bifurcation point using the method of multiple scales (MMS). Analysis has been performed for general values of the parameters, but the results are demonstrated for parameter values of the model corresponding to the advanced heavy water reactor (AHWR). The neutronics of the AHWR is modeled using point reactor kinetic equations while a one-node lumped parameter model is assumed both for the fuel and the coolant for modeling the thermal-hydraulics. Nonlinearities in the heat transfer process are ignored and attention is focused on the nonlinearity introduced by the reactivity feedback. It is found that the steady-state operation of the AHWR mathematical model looses stability via. a Hopf bifurcation resulting in power oscillations as some typical bifurcation parameter like the void coefficient of reactivity is varied. The bifurcation is found to be subcritical for the parameter values corresponding to the AHWR. However, with a decrease in the fuel temperature coefficient of reactivity the bifurcation turns to supercritical implying global stability of the steady state operation in the linear stability regime. Moreover slight intrusion into the instability regime results in small-amplitude limit cycles leaving the possibility of retracting back to stable operation. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Point reactor models lumped-parameter models Nonlinear stability Hopf bifurcation Method of multiple scales

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：