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Continuous piecewise-linear, reduced-order electrochemical model for lithium-ion batteries in real-time applications

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JOURNAL OF POWER SOURCES 2017年 342卷 351-362页

作者： Farag, Mohammed Fleckenstein, Matthias Habibi, Saeid McMaster Univ CMHT Dept Mech Engn JHE 316-1280 Main St West Hamilton ON L8S 4L8 Canada BMW Grp Battery Technol D-80788 Munich Germany

model-order reduction and minimization of the CPU run-time while maintaining the model accuracy are critical requirements for real-time implementation of lithium-ion electrochemical battery models. In this paper, an isothermal, continuous, piecewise-linear, electrode-average model is developed by using an optimal knot placement technique. The proposed model reduces the univariate nonlinear function of the electrode's open circuit potential dependence on the state of charge to continuous piecewise regions. The parameterization experiments were chosen to provide a trade-off between extensive experimental characterization techniques and purely identifying all parameters using optimization techniques. The model is then parameterized in each continuous, piecewise-linear, region. Applying the proposed technique cuts down the CPU run-time by around 20%, compared to the reduced-order, electrode average model. Finally, the model validation against real-time driving profiles (FTP-72, WLTP) demonstrates the ability of the model to predict the cell voltage accurately with less than 2% error. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Lithium-ion battery Electrochemical modeling model parameterization Piecewise linearization Knot placement Battery management system

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A comparison of discrete versus continuous adjoint states to invert groundwater flow in heterogeneous dual porosity systems

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ADVANCES IN WATER RESOURCES 2017年第Dec.期110卷 1-18页

作者： Delay, Frederick Badri, Hamid Fahs, Marwan Ackerer, Philippe Univ Strasbourg Lab Hydrol & Geochim Strasbourg EOST CNRSUMR 7517 1 Rue Blessig F-67000 Strasbourg France

Dual porosity models become increasingly used for simulating groundwater flow at the large scale in fractured porous media. In this context, model inversions with the aim of retrieving the system heterogeneity are frequently faced with huge parameterizations for which descent methods of inversion with the assistance of adjoint state calculations are well suited. We compare the performance of discrete and continuous forms of adjoint states associated with the flow equations in a dual porosity system. The discrete form inherits from previous works by some of the authors, as the continuous form is completely new and here fully differentiated for handling all types of model parameters. Adjoint states assist descent methods by calculating the gradient components of the objective function, these being a key to good convergence of inverse solutions. Our comparison on the basis of synthetic exercises show that both discrete and continuous adjoint states can provide very similar solutions close to reference. For highly heterogeneous systems, the calculation grid of the continuous form cannot be too coarse, otherwise the method may show lack of convergence. This notwithstanding, the continuous adjoint state is the most versatile form as its non-intrusive character allows for plugging an inversion toolbox quasi-independent from the code employed for solving the forward problem.

关键词： Adjoint state calculations Parameter field identification model parameterization Descent direction methods Fractured systems

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Combined electrochemical, heat generation, and thermal model for large prismatic lithium-ion batteries in real-time applications

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JOURNAL OF POWER SOURCES 2017年第Aug.31期360卷 618-633页

作者： Farag, Mohammed Sweity, Haitham Fleckenstein, Matthias Habibi, Saeid McMaster Univ Dept Mech Engn CMHT Hamilton ON L8S 4L8 Canada Tech Univ Muenchen Inst Elect Energy Storage Technol Arcisstrae 21 D-80333 Munich Germany BMW Grp Battery Technol D-80788 Munich Germany

Real-time prediction of the battery's core temperature and terminal voltage is very crucial for an accurate battery management system. In this paper, a combined electrochemical, heat generation, and thermal model is developed for large prismatic cells. The proposed model consists of three sub-models, an electrochemical model, heat generation model, and thermal model which are coupled together in an iterative fashion through physicochemical temperature dependent parameters. The proposed parameterization cycles identify the sub-models' parameters separately by exciting the battery under isothermal and non-isothermal operating conditions. The proposed combined model structure shows accurate terminal voltage and core temperature prediction at various operating conditions while maintaining a simple mathematical structure, making it ideal for real-time BMS applications. Finally, the model is validated against both isothermal and non-isothermal drive cycles, covering a broad range of C-rates, and temperature ranges [-25 degrees C to 45 degrees C]. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Lithium-ion battery Electrochemical model Thermal model Embedded-thermocouples model parameterization Internal temperature measurement Battery management system

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Evaluating the impacts of agricultural land management practices on water resources: A probabilistic hydrologic modeling approach

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JOURNAL OF ENVIRONMENTAL MANAGEMENT 2017年 193卷 512-523页

作者： Prada, A. F. Chu, M. L. Guzman, J. A. Moriasi, D. N. Univ Illinois Agr & Biol Engn 1304 W Penn Ave Urbana IL 61801 USA Univ Oklahoma Ctr Spatial Anal Dept Microbiol & Plant Biol Norman OK 73019 USA USDA ARS Grazinglands Res Lab 7207 W Cheyenne St El Reno OK 73036 USA

Evaluating the effectiveness of agricultural land management practices in minimizing environmental impacts using models is challenged by the presence of inherent uncertainties during the model development stage. One issue faced during the model development stage is the uncertainty involved in model parameterization. Using a single optimized set of parameters (one snapshot) to represent baseline conditions of the system limits the applicability and robustness of the model to properly represent future or alternative scenarios. The objective of this study was to develop a framework that facilitates model parameter selection while evaluating uncertainty to assess the impacts of land management practices at the watershed scale. The model framework was applied to the Lake Creek watershed located in southwestern Oklahoma, USA. A two-step probabilistic approach was implemented to parameterize the Agricultural Policy/Environmental eXtender (APEX) model using global uncertainty and sensitivity analysis to estimate the full spectrum of total monthly water yield (WYLD) and total monthly Nitrogen loads (N) in the watershed under different land management practices. Twenty-seven models were found to represent the baseline scenario in which uncertainty of up to 29% and 400% in WYLD and N, respectively, is plausible. Changing the land cover to pasture manifested the highest decrease in N to up to 30% for a full pasture coverage while changing to full winter wheat cover can increase the N up to 11%. The methodology developed in this study was able to quantify the full spectrum of system responses, the uncertainty associated with them, and the most important parameters that drive their variability. Results from this study can be used to develop strategic decisions on the risks and tradeoffs associated with different management alternatives that aim to increase productivity while also minimizing their environmental impacts. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： APEX model Global uncertainty and sensitivity analysis model parameterization Best management practices Probabilistic approach Water quality

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A field-based parameterization of wind flow recovery in the lee of dryland plants

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EARTH SURFACE PROCESSES AND LANDFORMS 2017年第2期42卷 378-386页

作者： Mayaud, Jerome R. Wiggs, Giles F. S. Bailey, Richard M. Univ Oxford Ctr Environm Sch Geog & Environm Oxford OX1 3QY England

Wind erosion is a key component of land degradation in vulnerable dryland regions. Despite a wealth of studies investigating the impact of vegetation and windbreaks on windflow in controlled wind-tunnel and modelling environments, there is still a paucity of empirical field data for accurately parameterizing the effect of vegetation in wind and sediment transport models. The aim of this study is to present a general parameterization of wind flow recovery in the lee of typical dryland vegetation elements (grass clumps and shrubs), based on their height (h) and optical porosity (theta). Spatial variations in mean wind velocity around eight isolated vegetation elements in Namibia (three grass clumps and five shrubs) were recorded at 0.30m height, using a combination of sonic and cup anemometry sampled at a temporal frequency of 10seconds. Wind flow recovery in the lee of the elements was parameterized in an exponential form, (u(ref)-u(0)).1-e(-bx/h) + u(0). The best-fit parameters derived from the field data were u(0)=u(ref)(0.0146 theta - 0.4076) and b = 0.0105 theta + 0.1627 . By comparing this parameterization to existing models, it is shown that wind recovery curves derived from two-dimensional wind fence experiments may not be suitable analogues for describing airflow around more complex, three-dimensional forms. Field-derived parameterizations such as the one presented here are a crucial step for connecting plant-scale windflow behaviour to dryland bedform development at landscape scales. (c) 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

关键词： dryland vegetation wind erosion model parameterization flow recovery

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Sensitivity analyses of acoustic impedance inversion with full-waveform inversion

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JOURNAL OF GEOPHYSICS AND ENGINEERING 2018年第2期15卷 461-477页

作者： Yao, Gang da Silva, Nuno V. Wu, Di Imperial Coll London Dept Earth Sci & Engn London SW7 2BP England China Univ Petr Unconvent Nat Gas Inst Beijing 102249 Peoples R China

Acoustic impedance estimation has a significant importance to seismic exploration. In this paper, we use full-waveform inversion to recover the impedance from seismic data, and analyze the sensitivity of the acoustic impedance with respect to the source-receiver offset of seismic data and to the initial velocity model. We parameterize the acoustic wave equation with velocity and impedance, and demonstrate three key aspects of acoustic impedance inversion. First, short-offset data are most suitable for acoustic impedance inversion. Second, acoustic impedance inversion is more compatible with the data generated by density contrasts than velocity contrasts. Finally, acoustic impedance inversion requires the starting velocity model to be very accurate for achieving a high-quality inversion. Based upon these observations, we propose a workflow for acoustic impedance inversion as: (1) building a background velocity model with travel-time tomography or reflection waveform inversion;(2) recovering the intermediate wavelength components of the velocity model with full-waveform inversion constrained by Gardner's relation;(3) inverting the high-resolution acoustic impedance model with short-offset data through full-waveform inversion. We verify this workflow by the synthetic tests based on the Marmousi model.

关键词： acoustic impedance full-waveform inversion model parameterization short offset reflection

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modeling leaf area index in North America using a process-based terrestrial ecosystem model

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ECOSPHERE 2018年第1期9卷

作者： Qu, Yang Zhuang, Qianlai Purdue Univ Dept Earth Atmospher & Planetary Sci 550 Stadium Mall Dr W Lafayette IN 47907 USA Purdue Univ Dept Agron 915 W State St W Lafayette IN 47907 USA

Leaf area index (LAI) is often used to quantify plant production and evapotranspiration with terrestrial ecosystem models (TEMs). This study evaluated the LAI simulation in North America using a data assimilation technique and a process-based TEM as well as insitu and satellite data. We first optimized the parameters related to LAI in the TEM using a Markov Chain Monte Carlo method, and AmeriFlux site-level and regional LAI data from advanced very high-resolution radiometer. The parameterized model was then verified with the observed monthly LAI of major ecosystem types at site level. Simulated LAI was compared well with the observed data at sites of Harvard Forest (R-2 = 0.96), University of Michigan Biological Station (R-2 = 0.87), Howland Forest (R-2 = 0.96), Morgan Monroe State Forest (R-2 = 0.85), Shidler Tallgrass Prairie (R-2 = 0.82), and Donaldson (R-2 = 0.75). The root-mean-square error (RMSE) between modeled and satellite-based monthly LAI in North America is 1.4 m(2)/m(2) for the period of 1985-2010. The simulated average monthly LAI in recent three decades increased by (3 +/- 0.5)% in the region, with 1.24, 1.46, and 2.21 m(2)/m(2) on average, in Alaska, Canada, and the conterminous United States, respectively, which is consistent with satellite data. The model performed well for wet tundra, boreal forest, temperate coniferous forests, temperate deciduous forests, grasslands, and xeric shrublands (RMSE < 1.5 m(2)/m(2)), but not for alpine tundra and xeric woodlands (RMSE > 1.5 m(2)/m(2)). Both the spring and fall LAI in the 2000s are higher than that in the 1980s in the region, suggesting that the leaf phenology has an earlier onset and later senescence in the 2000s. The average LAI increased in April and September by 0.03 and 0.24 m(2)/m(2), respectively. This study provides a way to quantify LAI with ecosystem models, which will improve future carbon and water cycling studies.

关键词： leaf area index (LAI) model parameterization phenology terrestrial ecosystem model (TEM)

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New Perspectives in Clinical Pharmacokinetics-1: the Importance of Updating the Teaching in Pharmacokinetics that both Clearance and Elimination Rate Constant Approaches Are Mathematically Proven Equally Valid

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AAPS JOURNAL 2018年第2期20卷 36-36页

作者： Jelliffe, Roger Bayard, David Univ Southern Calif USC Lab Appl Pharmacokinet & Bioinformat Sch Med Childrens Hosp Los Angeles 4650 Sunset Blvd51 Los Angeles CA 90027 USA

The healing professions have only about four main therapeutic tools at their disposal-surgery, drugs, physical therapy, and psychotherapy. For the general profession of internal medicine, drug therapy is its primary tool. Providing an understanding of the state-of-the-art in therapeutic methods, grounded in solid scientific and mathematical rigor, is therefore of the utmost clinical importance for both physicians and clinical pharmacists. This is particularly true where rapidly evolving scientific changes require an up-to-date education upon which students can rely. Unfortunately, relatively little attention has been paid to training clinical pharmacokineticists and physicians to manage drug therapy optimally for patients under their care in their everyday practice. In this paper, we discuss one of these basic deficiencies from the perspective of the longstanding controversy in pharmacokinetic modeling: whether the volume and clearance approach or the volume and rate constant approach is somehow "better". We examine this controversy using the mathematical principle of invariance, which to our knowledge has not been done before. The conclusion of this analysis is that both approaches are rigorously proven mathematically to be equally valid. We also discuss some implications of these equally valid approaches from the framework of mechanistic and non-compartmental models. Ultimately, the conclusion is that the choice of one parameterization over the other is based on preference or usefulness for research or clinical practice, but no longer, because of this analysis, on science.

关键词： clearance model parameterization pharmacokinetics rate constant

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Response to O'Leary et al.: Misuse of models Leads to Misguided Conservation Recommendations

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CONSERVATION LETTERS 2017年第2期10卷 269-270页

作者： White, J. Wilson Nickols, Kerry J. Botsford, Louis W. Univ North Carolina Wilmington Dept Biol & Marine Biol 601 S Coll Rd Wilmington NC 28403 USA Calif State Univ Monterey Bay Sch Nat Sci Seaside CA 93955 USA Univ Calif Davis Dept Wildlife Fish & Conservat Biol Davis CA 95616 USA

O'Leary et al. sought to evaluate the scientific basis for global targets for marine protected area (MPA) coverage (e.g., 10% of marine habitats) using a meta-analysis of published MPA modeling studies. Unfortunat... 详细信息

关键词： Global conservation targets marine protected areas meta-analysis models model parameterization

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Identification and estimation of causal effects with outcomes truncated by death

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BIOMETRIKA 2017年第3期104卷 597-612页

作者： Wang, Linbo Zhou, Xiao-Hua Richardson, Thomas S. Harvard Sch Publ Hlth Dept Biostat 677 Huntington Ave Boston MA 02115 USA Univ Washington Dept Biostat Seattle WA 98195 USA Univ Washington Dept Stat Seattle WA 98195 USA

It is common in medical studies that the outcome of interest is truncated by death, meaning that a subject has died before the outcome could be measured. In this case, restricted analysis among survivors may be subject to selection bias. Hence, it is of interest to estimate the survivor average causal effect, defined as the average causal effect among the subgroup consisting of subjects who would survive under either exposure. In this paper, we consider the identification and estimation problems of the survivor average causal effect. We propose to use a substitution variable in place of the latent membership in the always-survivor group. The identification conditions required for a substitution variable are conceptually similar to conditions for a conditional instrumental variable, and may apply to both randomized and observational studies. We show that the survivor average causal effect is identifiable with use of such a substitution variable, and propose novel model parameterizations for estimation of the survivor average causal effect under our identification assumptions. Our approaches are illustrated via simulation studies and a data analysis.

关键词： Causal inference Instrumental variable model parameterization Principal stratification Survivor average causal effect

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