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Measurement of model parameters Versus Gas Pressure in High-Performance Plasma Focus NX1 and NX2 Operated in Neon

IEEE TRANSACTIONS ON PLASMA SCIENCE 2017年第8期45卷 2292-2297页

作者： Gautam, Prakash Khanal, Raju Saw, Sor Heoh Lee, Sing Tribhuvan Univ Cent Dept Phys Kathmandu 44613 Nepal Nilai Univ Nilai 71800 Malaysia Inst Plasma Focus Studies Chadstone Vic 3148 Australia Inst Plasma Focus Studies Melbourne Vic 3148 Australia INTI Int Univ Nilai 71800 Malaysia

Measured current waveforms at different neon pressures from two different plasma focus (PF) devices, namely, NX2 and NX1 are used for analysis using the Lee code. The model parameters of mass (f(m) and f(mr)) and current (f(c) and f(cr)) in axial and radial phase, respectively, are obtained by fitting the computed current waveform to the measured current waveform for each pressure over a range of pressures in neon. The results show that the value of fm and fmr ranges from 0.07 to 0.12 and 0.09 to 0.20, respectively, over the pressure range 1.0-5.0 Torr for NX2, whereas for NX1 it ranges from 0.020 to 0.024 and 0.048 to 0.08, respectively, over the pressure range 7.5-12 Torr. In all cases, the values of f(c) and f(cr) are fixed at 0.7. Comparison of computed and measured soft X-ray (SXR) yield using fit model parameters for both devices shows good agreement. An important finding is that despite the noticeable variation of mass factors over the whole pressure range, a representative set of model parameters is found for each machine which may be taken as fixed over the range of pressures producing a good yield. In particular, for a high-performance PF using conventional electrode structure the representative set is: f(m) = 0.075, f(c) = 0.7, f(mr) = 0.1, and f(cr) = 0.7. This is valuable information for neon SXR design purposes.

关键词： Lee model code model parameters plasma applications plasma focus (PF) plasma properties soft X-ray

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A predator-prey based mathematical model of the bone remodelling cycle: Exploring the relationship between the model parameters and biochemical factors

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE 2014年第10期228卷 1035-1042页

作者： Ji, Bing Yang, Qing Genever, Paul G. Patton, Ronald J. Fagan, Michael J. Shandong Univ Sch Control Sci & Engn Jinan 250061 Peoples R China Shandong Univ Shandong Prov Hosp Jinan 250061 Peoples R China Univ York Dept Biol York YO10 5DD N Yorkshire England Univ Hull Sch Engn Kingston Upon Hull HU6 7RX N Humberside England

Bone remodelling is a vital process which enables bone to repair, renew and optimize itself. Disorders in the bone remodelling process are inevitably manifested in bone-related diseases, such as hypothyroidism, primary hyperparathyroidism and osteoporosis. In our previous work, a predator-prey based mathematical model was developed to simulate bone remodelling cycles under normal and two pathological conditions, hypothyroidism and primary hyperparathyroidism, for trabecular bone at a fixed point. However, the biochemical meanings of the model parameters were not fully explored. This article first extends the previous work by proposing relationships between the model parameters and biochemical factors involved in the bone remodelling process and by examining whether those relationships do predict the behaviours observed in vivo. The model is then applied to the simulation and investigation of bone remodelling of postmenopausal osteoporosis. The proposed connections are supported by good agreement between the model simulations and published experimental observations for the normal condition and all three pathological variations in bone remodelling.

关键词： Bone remodelling mathematical model biochemical factors model parameters postmenopausal osteoporosis

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Vegetation-specific model parameters are not required for estimating gross primary production

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ECOLOGICAL modelLING 2014年第0期292卷 1-10页

作者： Yuan, Wenping Cai, Wenwen Liu, Shuguang Dong, Wenjie Chen, Jiquan Arain, M. Altaf Blanken, Peter D. Cescatti, Alessandro Wohlfahrt, Georg Georgiadis, Teodoro Genesio, Lorenzo Gianelle, Damiano Grelle, Achim Kiely, Gerard Knohl, Alexander Liu, Dan Marek, Michal V. Merbold, Lutz Montagnani, Leonardo Panferov, Oleg Peltoniemi, Mikko Rambal, Serge Raschi, Antonio Varlagin, Andrej Xia, Jiangzhou Beijing Normal Univ State Key Lab Earth Surface Proc & Resource Beijing 100875 Peoples R China Beijing Normal Univ Zhuhai Future Earth Res Inst Zhuhai 519087 Peoples R China Cent South Univ Forestry & Technol State Engn Lab Southern Forestry Appl Ecol & Tech Changsha 410004 Hunan Peoples R China Nanjing Univ Informat Sci & Technol Sch Appl Meteorol Int Ctr Ecol Meteorol & Environm Nanjing 210044 Jiangsu Peoples R China Michigan State Univ CGCEO Geog E Lansing MI 48824 USA McMaster Univ Sch Geog & Earth Sci Hamilton ON Canada Univ Colorado Dept Geog Boulder CO 80309 USA Commiss European Communities Joint Res Ctr Inst Environm & Sustainabil I-21020 Ispra Italy Univ Innsbruck Inst Ecol A-6020 Innsbruck Austria IBIMET CNR Inst Biometeorol I-40129 Bologna Italy IBIMET CNR Inst Biometeorol I-50145 Florence Italy Fdn E Mach Res & Innovat Ctr Sustainable Agroecosyst & Bioresources Dept San Michele All Adige Italy Swedish Univ Agr Sci Dept Ecol S-75007 Uppsala Sweden Natl Univ Ireland Univ Coll Cork Dept Civil & Environm Engn Cork Ireland Natl Univ Ireland Univ Coll Cork Environm Res Inst Cork Ireland Univ Gottingen Busgen Inst Bioclimatol Grp D-37073 Gottingen Germany Mendel Univ Brno Dept Forest Ecol Brno 60300 Czech Republic ETH Inst Agr Sci Dept Environm Syst Sci CH-8092 Zurich Switzerland Forest Serv Autonomous Prov Bolzano Bolzano Italy Free Univ Bolzano Fac Sci & Technol I-39100 Bolzano Italy Finnish Forest Res Inst FIN-01301 Vantaa Finland CNRS CEFE DREAM UMR5175 F-34293 Montpellier 5 France Russian Acad Sci AN Severtsov Inst Ecol & Evolut Moscow 119071 Russia

models of gross primary production (GPP) based on remote sensing measurements are currently parameterized with vegetation-specific parameter sets and therefore require accurate information on the distribution of vegetation to drive them. Can this parameterization scheme be replaced with a vegetation-invariant set of parameters that can maintain or increase model applicability by reducing errors introduced from the uncertainty of land cover classification? Based on the measurements of ecosystem carbon fluxes from 168 globally distributed sites in a range of vegetation types, we examined the predictive capacity of seven light use efficiency (LUE) models. Two model experiments were conducted: (i) a constant set of parameters for various vegetation types and (ii) vegetation-specific parameters. The results showed no significant differences in model performance in simulating GPP while using both set of parameters. These results indicate that a universal of set of parameters, which is independent of vegetation cover type and characteristics can be adopted in prevalent LUE models. Availability of this well tested and universal set of parameters would help to improve the accuracy and applicability of LUE models in various biomes and geographic regions. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Light use efficiency Gross primary production model parameters

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Relating model parameters to basic soil properties

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AUSTRALIAN JOURNAL OF SOIL RESEARCH 2004年第7期42卷 841-849页

作者： Merdun, H Quisenberry, VL Kahramanmaras Sutcu Imam Univ Fac Agr Dept Agr Struct & Irrigat TR-46060 Kahramanmaras Turkey Clemson Univ Dept Crop & Soil Environm Sci Clemson SC 29634 USA

Relating model parameters to basic soil characteristics can help to differentiate and classify soils based on their flow and transport characteristics and ultimately helps to develop a sound management tool to protect groundwater from industrial and agricultural contaminants. In this study, the model parameters (effective diffusion path-length or aggregate half-width, boundary soil water pressure, boundary hydraulic conductivity, saturated hydraulic conductivity, tortuosity in macropores, dispersivity, mixing depth) obtained from simulation of water flow and solute transport for 3 soils (Maury, Cecil, Lakeland) with contrasting properties were related to see whether these derived parameters can be related to variation in fundamental soil properties such as texture and structure and thus the flow and transport characteristics of the soils. The boundary is a division point in which the soil porosity is divided into macropores and micropores. The ANOVA test showed that the parameter values of effective diffusion path-length and tortuosity in macropores for 3 soils were not different from each other, but the parameter values of saturated and boundary hydraulic conductivities including the texture (clay content) were statistically different. Moreover, the means of boundary soil water pressure, dispersivity, and mixing depth for 3 soils were significantly different. These results suggest that relating model parameters to basic soil properties in order to differentiate and classify soils based on their flow and transport characteristics is promising and needs further study.

关键词： preferential flow solute transport soil properties model parameters displacement boundary pressure

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A kinetic model for heap leaching of uranium ore considering variation of model parameters with depth of heap

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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 2013年第3期298卷 1477-1482页

作者： Ding, De-xin Song, Jian-bin Ye, Yong-jun Li, Guang-yue Fu, Hai-ying Hu, Nan Wang, Yong-dong Univ South China Key Discipline Lab Natl Def Biotechnol Uranium Mi Hengyang 421001 Peoples R China

Many kinetic models for heap leaching of low grade ores have been proposed and the model parameters have been treated as constants. However, some of these model parameters change with the depth of the heap. In the present work an apparatus consisted of six columns with different heights was designed and used to simulate the leaching behavior within a 3-m-high uranium ore heap at a uranium mine in South China. It was found that the model parameters alpha and omega for heap leaching of the uranium ore varied with the depth of the heap, and that the relationships between alpha and between omega and the depth of the heap were in the form of the logistic and the quadratic functions, respectively. Furthermore, a kinetic model for heap leaching of the uranium ore considering the variation of the model parameters with the depth of the ore was proposed. The kinetic model gave the fitting precision of more than 95 % and prediction precision of more than 93 %. The present work provided an approach for establishing the kinetic model for heap leaching of low grade uranium ores.

关键词： Kinetic model Uranium ore Heap leaching model parameters Heap depth

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Regionalisation of hydrological model parameters under parameter uncertainty: A case study involving TOPmodel and basins across the globe

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JOURNAL OF HYDROLOGY 2008年第3-4期357卷 188-206页

作者： Bastola, Satish Ishidaira, Hiroshi Takeuchi, Kuniyoshi Yamanashi Univ Dept Civil & Environm Engn Kofu Yamanashi 400 Japan Int Ctr Water Hazard & Risk Management Tsukuba Ibaraki 3058516 Japan

In this paper, we present a method to account for modeling uncertainties while regionalising model parameters. Linking model. parameters to physical catchment attributes is a popular approach that enables the application of a conceptual model to an ungauged site. The functional relationship can be derived either from the calibrated model. parameters (direct calibration method) or by calibrating the functional. function (regional. calibration method). Both of these approaches are explored through a case study involving TOPmodel and a number of small- to medium-sized humid basins located in various geographic and climatic regions around the globe. The predictive performance of the functional relationship derived using the direct calibration method (e.g., multiple regression, artificial neural. network and partial least square regression) varied among the different schemes. However, the average of the model. parameters estimated from regionatisation schemes based on direct calibration is found to be a better surrogate. Even with the use of a parsimonious hydrological model and with posing model calibration as a multi-objective problem, the model. parameter uncertainty and its effect on model. prediction were observed to be high and varied among the basins. Therefore, to avoid the effect of model parameter uncertainty on regionalization results, a regional calibration method that skips direct calibration of the hydrological model was implemented. This method was improved in order to take into account multiple objective criteria white calibrating regional parameters. The predictive performance of the improved regional calibration method was found to be superior to the direct calibration method, indicating that the identifiability of model parameters has an apparent effect on deriving predictive models for regionalisation. However, the regional calibration method was unable to uniquely identify the regional relationship, and the modeling uncertainties quantified using Par

关键词： conceptual rainfall-runoff models multi-objective calibration model parameters parameter uncertainty regionalisation

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Effect of spatial resolution on regionalization of hydrological model parameters

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HYDROLOGICAL PROCESSES 2012年第23期26卷 3499-3509页

作者： Singh, Shailesh Kumar Bardossy, Andras Goetzinger, J. Sudheer, K. P. Natl Inst Water & Atmospher Res Ltd 10 Kyle St Christchurch 8011 New Zealand Univ Stuttgart Inst Hydraul Engn Stuttgart Germany Saarland Minist Environm Saarbrucken Germany Indian Inst Technol Madras Dept Civil Engn Madras Tamil Nadu India

Lack of availability of historical data series is one of the major hindrances in hydrological modelling. Regionalization of hydrological model parameters is one of the solutions to obtain the parameters for ungauged basins. Recently, lots of methodologies have been developed. They can be categorized as model calibration then fitting regression between model parameters and catchments characteristics, using some kind of transfer function. The aim of this study was to compare different regionalization methods as well as to look how the spatial resolution affects regionalization. In this study, a modified Lipschitz and monotony condition was used for regionalization. To identify the effect of the model resolution, the parameters of a distributed and semi-distributed version of the Hydrologiska Byrans Vattenbalansavdelning (HBV) model were regionalized. The study was conducted at the upper Neckar catchment of southwest Germany. It has been found that the combination of Lipschitz and monotony condition has performed reasonably. It has been seen that the distributed model structure has outperformed the semi-distributed model structure. It shows under present data conditions that higher model resolution can describe processes of ungauged basins reasonably. Copyright (c) 2011 John Wiley & Sons, Ltd.

关键词： Spatial resolution decentralised control Basins parameters Monotony model structures Catchment area model parameters basins Hydrologic models data sequence

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First-order kinetic gas generation model parameters for wet landfills

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WASTE MANAGEMENT 2007年第7期27卷 946-953页

作者： Faour, Ayman A. Reinhart, Debra R. You, Huaxin Univ Cent Florida Orlando FL 32816 USA Univ Cent Florida Orlando FL 32816 USA

Landfill gas collection data from wet landfill cells were analyzed and first-order gas generation model parameters were estimated for the US EPA landfill gas emissions model (LandGEM). parameters were determined through statistical comparison of predicted and actual gas collection. The US EPA LandGEM model appeared to fit the data well, provided it is preceded by a lag phase, which on average was 1.5 years. The first-order reaction rate constant, k, and the methane generation potential, Lo, were estimated for a set of landfills with short-term waste placement and long-term gas collection data. Mean and 95% confidence parameter estimates for these data sets were found using mixed-effects model regression followed by bootstrap analysis. The mean values for the specific methane volume produced during the lag phase (V,,,,), Lo, and k were 33 m(3)/Megagrams (Mg), 76 m(3)/Mg, and 0.28 year(-1), respectively. parameters were also estimated for three full scale wet landfills where waste was placed over many years. The k and L. estimated for these landfills were 0.21 year(-1), 115 m(3)/Mg, 0.11 year 1, 95 m(3)/M g, and 0.12 year(-1) and 87 m(3)/Mg, respectively. A group of data points from wet landfills cells with short-term data were also analyzed. A conservative set of parameter estimates was suggested based on the upper 95% confidence interval parameters as a k of 0.3 year(-1) and a L. of 100 m(3)/Mg if design is optimized and the lag is minimized. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： Lag phase model parameters Landfills Dataset Gas holders

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etas_solve: A Robust Program to Estimate the ETAS model parameters

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SEISMOLOGICAL RESEARCH LETTERS 2016年第5期87卷 1143-1149页

作者： Kasahara, Amato Yagi, Yuji Enescu, Bogdan Univ Tsukuba Grad Sch Life & Environm Sci Tennodai 1-1-1 Ibaraki 3058572 Japan Univ Tsukuba Fac Life & Environm Sci Tennodai 1-1-1 Ibaraki 3058572 Japan Kyoto Univ Grad Sch Sci Dept Geophys Sakyo Ku Oiwake Cho Kyoto 6068502 Japan

The temporal epidemic-type aftershock sequence (ETAS) model is widely used to describe seismicity. However, only a few programs for estimation of the temporal ETAS model parameters are publicly available, and it is difficult to routinely apply some of them to observed data, due to initial value dependence. A robust temporal ETAS estimation program is required to routinely process earthquake catalogs or to perform Monte Carlo simulations. In this study, we developed a new Fortran program, etas_solve, which is based on the steepest descent method and calculates exact gradient and Hessian using the automatic differentiation technique. We performed numerical tests for a real earthquake catalog and for synthetic catalogs. Through the numerical tests, we found that initial value dependence of etas_solve is several orders of magnitude smaller than that of statistical analysis of point processes (SAPP), which is an R wrapper of statistical analysis of seismicity. We also found that standard error estimated from a Hessian at a maximum-likelihood estimate (MLE) is useful to quantify the uncertainty of the MLE. Computation time of etas_solve was comparable to that of SAPP on a single-core machine and faster on a multicore machine (around eightfold speed up on a 16-core machine). In addition, etas_solve provides rich features that may be useful in real-world applications, such as options to use fixed parameters and an auxiliary window in time and magnitude.

关键词： observational data Monte Carlo technique seismicity Hessian core machine Robustness steepest descent method machine Statistical methods Standard error catalogs maximum likelihood estimation model parameters

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Correlation of vehicle crash model parameters to car properties in low-speed collisions: a design of experiments approach

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INTERNATIONAL JOURNAL OF CRASHWORTHINESS 2010年第3期15卷 241-249页

作者： Isaksson, E. Jonsen, P. Sundin, K. G. Oldenburg, M. Lulea Univ Technol Div Solid Mech S-97187 Lulea Sweden

In the current study, a methodology for relating model parameters in a one dimensional Mass Spring Damper (MSD) model to global properties of a car, e.g. axial stiffness, bending stiffness and mass, is presented. It is shown that these three vehicle properties affect the vehicle's crash performance in low-speed collision tests used for industrial verification of bumper system performance. Based on information of the properties for a vehicle under development, parameters in the MSD model can be adjusted to give the correct boundary conditions for a finite element (FE) crash simulation with a candidate bumper design. In the FE simulations, the MSD model is then coupled to the FE mesh of candidate bumper design to find a bumper that meets the crash performance requirements of a car under development. The methodology is based on Design of Experiments (DOE) and FE simulations on a public domain model of a Ford Taurus. The knowledge gained from this study gives a valuable tool to use in design and development of bumper systems for the automotive industry.

关键词： bumper system car crash model design of experiments model parameters vehicle properties

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