Science.gov

Sample records for ii model validation

  1. Large-scale Validation of AMIP II Land-surface Simulations: Preliminary Results for Ten Models

    SciTech Connect

    Phillips, T J; Henderson-Sellers, A; Irannejad, P; McGuffie, K; Zhang, H

    2005-12-01

    This report summarizes initial findings of a large-scale validation of the land-surface simulations of ten atmospheric general circulation models that are entries in phase II of the Atmospheric Model Intercomparison Project (AMIP II). This validation is conducted by AMIP Diagnostic Subproject 12 on Land-surface Processes and Parameterizations, which is focusing on putative relationships between the continental climate simulations and the associated models' land-surface schemes. The selected models typify the diversity of representations of land-surface climate that are currently implemented by the global modeling community. The current dearth of global-scale terrestrial observations makes exacting validation of AMIP II continental simulations impractical. Thus, selected land-surface processes of the models are compared with several alternative validation data sets, which include merged in-situ/satellite products, climate reanalyses, and off-line simulations of land-surface schemes that are driven by observed forcings. The aggregated spatio-temporal differences between each simulated process and a chosen reference data set then are quantified by means of root-mean-square error statistics; the differences among alternative validation data sets are similarly quantified as an estimate of the current observational uncertainty in the selected land-surface process. Examples of these metrics are displayed for land-surface air temperature, precipitation, and the latent and sensible heat fluxes. It is found that the simulations of surface air temperature, when aggregated over all land and seasons, agree most closely with the chosen reference data, while the simulations of precipitation agree least. In the latter case, there also is considerable inter-model scatter in the error statistics, with the reanalyses estimates of precipitation resembling the AMIP II simulations more than to the chosen reference data. In aggregate, the simulations of land-surface latent and sensible

  2. A scattering model for perfectly conducting random surfaces. I - Model development. II - Range of validity

    NASA Technical Reports Server (NTRS)

    Fung, A. K.; Pan, G. W.

    1987-01-01

    The surface current on a perfectly conducting randomly rough surface is estimated by solving iteratively a standard integral equation, and the estimate is then used to compute the far-zone scattered fields and the backscattering coefficients for vertical, horizontal and cross polarizations. The model developed here yields a simple backscattering coefficient expression in terms of the surface parameters. The expression reduces analytically to the Kirchhoff and the first-order small-perturbation model in the high- and low-frequency regions, respectively. The range of validity of the model is determined.

  3. Validated Competing Event Model for the Stage I-II Endometrial Cancer Population

    SciTech Connect

    Carmona, Ruben; Gulaya, Sachin; Murphy, James D.; Rose, Brent S.; Wu, John; Noticewala, Sonal; McHale, Michael T.; Yashar, Catheryn M.; Vaida, Florin; Mell, Loren K.

    2014-07-15

    Purpose/Objectives(s): Early-stage endometrial cancer patients are at higher risk of noncancer mortality than of cancer mortality. Competing event models incorporating comorbidity could help identify women most likely to benefit from treatment intensification. Methods and Materials: 67,397 women with stage I-II endometrioid adenocarcinoma after total hysterectomy diagnosed from 1988 to 2009 were identified in Surveillance, Epidemiology, and End Results (SEER) and linked SEER-Medicare databases. Using demographic and clinical information, including comorbidity, we sought to develop and validate a risk score to predict the incidence of competing mortality. Results: In the validation cohort, increasing competing mortality risk score was associated with increased risk of noncancer mortality (subdistribution hazard ratio [SDHR], 1.92; 95% confidence interval [CI], 1.60-2.30) and decreased risk of endometrial cancer mortality (SDHR, 0.61; 95% CI, 0.55-0.78). Controlling for other variables, Charlson Comorbidity Index (CCI) = 1 (SDHR, 1.62; 95% CI, 1.45-1.82) and CCI >1 (SDHR, 3.31; 95% CI, 2.74-4.01) were associated with increased risk of noncancer mortality. The 10-year cumulative incidences of competing mortality within low-, medium-, and high-risk strata were 27.3% (95% CI, 25.2%-29.4%), 34.6% (95% CI, 32.5%-36.7%), and 50.3% (95% CI, 48.2%-52.6%), respectively. With increasing competing mortality risk score, we observed a significant decline in omega (ω), indicating a diminishing likelihood of benefit from treatment intensification. Conclusion: Comorbidity and other factors influence the risk of competing mortality among patients with early-stage endometrial cancer. Competing event models could improve our ability to identify patients likely to benefit from treatment intensification.

  4. Development of a livestock odor dispersion model: part II. Evaluation and validation.

    PubMed

    Yu, Zimu; Guo, Huiqing; Laguë, Claude

    2011-03-01

    A livestock odor dispersion model (LODM) was developed to predict odor concentration and odor frequency using routine hourly meteorological data input. The odor concentrations predicted by the LODM were compared with the results obtained from other commercial models (Industrial Source Complex Short-Term model, version 3, CALPUFF) to evaluate its appropriateness. Two sets of field odor plume measurement data were used to validate the model. The model-predicted mean odor concentrations and odor frequencies were compared with those measured. Results show that this model has good performance for predicting odor concentrations and odor frequencies. PMID:21416754

  5. A wheat grazing model for simulating grain and beef production: Part II - model validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Model evaluation is a prerequisite to its adoption and successful application. The objective of this paper is to evaluate the ability of a newly developed wheat grazing model to predict fall-winter forage and grain yields of winter wheat (Triticum aestivum L.) as well as daily weight gains per steer...

  6. A physical model of the bidirectional reflectance of vegetation canopies. I - Theory. II - Inversion and validation

    NASA Technical Reports Server (NTRS)

    Verstraete, Michel M.; Pinty, Bernard; Dickinson, Robert E.

    1990-01-01

    A new physically based analytical model of the bidirectional reflectance of vegetation canopies is derived. The model expresses the bidirectional reflectance field of a semiinfinite canopy as a combination of functions describing (1) the optical properties of the leaves through their single-scattering albedo and their phase function, (2) the average distribution of leaf orientations, and (3) the architecture of the canopy. The model is validated against laboratory and ground-based measurements in the visible and IR spectral regions, taken over two vegetation covers. The intrinsic optical properties of leaves and the information on the geometrical canopy arrangements in space were obtained using an inversion procedure based on a nonlinear optimization technique. Model predictions of bidirectional reflectances obtained using the inversion procedure compare well with actual observations.

  7. Southern california offshore air quality model validation study. Volume II: synthesis of findings. Final report

    SciTech Connect

    Zannetti, P.; Wilbur, D.M.; Baxter, R.A.

    1981-11-01

    This volume describes the significant results of a BLM-funded study conducted jointly by AeroVironment Inc. and the Naval Postgraduate School to validate and/or modify screening models commonly used to predict onshore air quality impacts from outer continental shelf (OCS) emission sources. The study involved both field experiments and computer modeling analysis to give a better understanding of dispersion over water and at the land/sea interface. Two field experiments were performed releasing SF tracer gas from a research vessel offshore the Ventura-Oxnard, California coastal area in September, 1980 and January, 1981. Modifications are discussed for standard Gaussian models to predict peak plume concentration values, the horizontal and vertical shape of the plume, and peak ground-level impacts from OCS emission sources.

  8. Fluids with competing interactions. II. Validating a free energy model for equilibrium cluster size

    NASA Astrophysics Data System (ADS)

    Bollinger, Jonathan A.; Truskett, Thomas M.

    2016-08-01

    Using computer simulations, we validate a simple free energy model that can be analytically solved to predict the equilibrium size of self-limiting clusters of particles in the fluid state governed by a combination of short-range attractive and long-range repulsive pair potentials. The model is a semi-empirical adaptation and extension of the canonical free energy-based result due to Groenewold and Kegel [J. Phys. Chem. B 105, 11702-11709 (2001)], where we use new computer simulation data to systematically improve the cluster-size scalings with respect to the strengths of the competing interactions driving aggregation. We find that one can adapt a classical nucleation like theory for small energetically frustrated aggregates provided one appropriately accounts for a size-dependent, microscopic energy penalty of interface formation, which requires new scaling arguments. This framework is verified in part by considering the extensive scaling of intracluster bonding, where we uncover a superlinear scaling regime distinct from (and located between) the known regimes for small and large aggregates. We validate our model based on comparisons against approximately 100 different simulated systems comprising compact spherical aggregates with characteristic (terminal) sizes between six and sixty monomers, which correspond to wide ranges in experimentally controllable parameters.

  9. Assessing the wildlife habitat value of New England salt marshes: II. Model testing and validation.

    PubMed

    McKinney, Richard A; Charpentier, Michael A; Wigand, Cathleen

    2009-07-01

    We tested a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. As a group, wildlife habitat value assessment scores for the marshes ranged from 307-509, or 31-67% of the maximum attainable score. We recorded 6 species of wading birds (Ardeidae; herons, egrets, and bitterns) at the sites during biweekly survey. Species richness (r (2)=0.24, F=4.53, p=0.05) and abundance (r (2)=0.26, F=5.00, p=0.04) of wading birds significantly increased with increasing assessment score. We optimized our assessment model for wading birds by using Akaike information criteria (AIC) to compare a series of models comprised of specific components and categories of our model that best reflect their habitat use. The model incorporating pre-classification, wading bird habitat categories, and natural land surrounding the sites was substantially supported by AIC analysis as the best model. The abundance of wading birds significantly increased with increasing assessment scores generated with the optimized model (r (2)=0.48, F=12.5, p=0.003), demonstrating that optimizing models can be helpful in improving the accuracy of the assessment for a given species or species assemblage. In addition to validating the assessment model, our results show that in spite of their urban setting our study marshes provide substantial wildlife habitat value. This suggests that even small wetlands in highly urbanized coastal settings can provide important wildlife habitat value if key habitat attributes (e.g., natural buffers, habitat heterogeneity) are present. PMID:18597178

  10. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Swissler, T. J.; Osborn, M. T.; Russell, P. B.; Oberbeck, V. R.; Livingston, J.; Rosen, J. M.

    1989-01-01

    Consideration is given to aerosol correlative measurements experiments for the Stratospheric Aerosol and Gas Experiment (SAGE) II, conducted between November 1984 and July 1986. The correlative measurements were taken with an impactor/laser probe, a dustsonde, and an airborne 36-cm lidar system. The primary aerosol quantities measured by the ground-based instruments are compared with those calculated from the aerosol size distributions from SAGE II aerosol extinction measurements. Good agreement is found between the two sets of measurements.

  11. Development and validation of an evaporation duct model. Part II: Evaluation and improvement of stability functions

    NASA Astrophysics Data System (ADS)

    Ding, Juli; Fei, Jianfang; Huang, Xiaogang; Cheng, Xiaoping; Hu, Xiaohua; Ji, Liang

    2015-06-01

    This study aims to validate and improve the universal evaporation duct (UED) model through a further analysis of the stability function ( ψ). A large number of hydrometeorological observations obtained from a tower platform near Xisha Island of the South China Sea are employed, together with the latest variations in ψ function. Applicability of different ψ functions for specific sea areas and stratification conditions is investigated based on three objective criteria. The results show that, under unstable conditions, ψ function of Fairall et al. (1996) (i.e., Fairall96, similar for abbreviations of other function names) in general offers the best performance. However, strictly speaking, this holds true only for the stability (represented by bulk Richardson number R iB) range -2.6 ⩽ R iB < -0.1; when conditions become weakly unstable (-0.1 ⩽ R iB < -0.01), Fairall96 offers the second best performance after Hu and Zhang (1992) (HYQ92). Conversely, for near-neutral but slightly unstable conditions (-0.01 ⩽ R iB < 0.0), the effects of Edson04, Fairall03, Grachev00, and Fairall96 are similar, with Edson04 being the best function but offering only a weak advantage. Under stable conditions, HYQ92 is the optimal and offers a pronounced advantage, followed by the newly introduced SHEBA07 (by Grachev et al., 2007) function. Accordingly, the most favorable functions, i.e., Fairall96 and HYQ92, are incorporated into the UED model to obtain an improved version of the model. With the new functions, the mean root-mean-square (rms) errors of the modified refractivity ( M), 0-5-m M slope, 5-40-m M slope, and the rms errors of evaporation duct height (EDH) are reduced by 21.65%, 9.12%, 38.79%, and 59.06%, respectively, compared to the classical Naval Postgraduate School model.

  12. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements.

    PubMed

    Wang, P H; McCormick, M P; McMaster, L R; Chu, W P; Swissler, T J; Osborn, M T; Russell, P B; Oberbeck, V R; Livingston, J; Rosen, J M; Hofmann, D J; Grams, G W; Fuller, W H; Yue, G K

    1989-06-20

    This paper describes an investigation of the comprehensive aerosol correlative measurement experiments conducted between November 1984 and July 1986 for satellite measurement program of the Stratospheric Aerosol and Gas Experiment (SAGE II). The correlative sensors involved in the experiments consist of the NASA Ames Research Center impactor/laser probe, the University of Wyoming dustsonde, and the NASA Langley Research Center airborne 14-inch (36 cm) lidar system. The approach of the analysis is to compare the primary aerosol quantities measured by the ground-based instruments with the calculated ones based on the aerosol size distributions retrieved from the SAGE II aerosol extinction measurements. The analysis shows that the aerosol size distributions derived from the SAGE II observations agree qualitatively with the in situ measurements made by the impactor/laser probe. The SAGE II-derived vertical distributions of the ratio N0.15/N0.25 (where Nr is the cumulative aerosol concentration for particle radii greater than r, in micrometers) and the aerosol backscatter profiles at 0.532- and 0.6943-micrometer lidar wavelengths are shown to agree with the dustsonde and the 14-inch (36-cm) lidar observations, with the differences being within the respective uncertainties of the SAGE II and the other instruments. PMID:11539801

  13. Person Heterogeneity of the BDI-II-C and Its Effects on Dimensionality and Construct Validity: Using Mixture Item Response Models

    ERIC Educational Resources Information Center

    Wu, Pei-Chen; Huang, Tsai-Wei

    2010-01-01

    This study was to apply the mixed Rasch model to investigate person heterogeneity of Beck Depression Inventory-II-Chinese version (BDI-II-C) and its effects on dimensionality and construct validity. Person heterogeneity was reflected by two latent classes that differ qualitatively. Additionally, person heterogeneity adversely affected the…

  14. Predictive modeling of infrared radiative heating in tomato dry-peeling process: Part II. Model validation and sensitivity analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A predictive mathematical model was developed to simulate heat transfer in a tomato undergoing double sided infrared (IR) heating in a dry-peeling process. The aims of this study were to validate the developed model using experimental data and to investigate different engineering parameters that mos...

  15. Validating the Serpent Model of FiR 1 Triga Mk-II Reactor by Means of Reactor Dosimetry

    NASA Astrophysics Data System (ADS)

    Viitanen, Tuomas; Leppänen, Jaakko

    2016-02-01

    A model of the FiR 1 Triga Mk-II reactor has been previously generated for the Serpent Monte Carlo reactor physics and burnup calculation code. In the current article, this model is validated by comparing the predicted reaction rates of nickel and manganese at 9 different positions in the reactor to measurements. In addition, track-length estimators are implemented in Serpent 2.1.18 to increase its performance in dosimetry calculations. The usage of the track-length estimators is found to decrease the reaction rate calculation times by a factor of 7-8 compared to the standard estimator type in Serpent, the collision estimators. The differences in the reaction rates between the calculation and the measurement are below 20%.

  16. Black liquor combustion validated recovery boiler modeling: Final year report. Volume 2 (Appendices I, section 5 and II, section 1)

    SciTech Connect

    Grace, T.M.; Frederick, W.J.; Salcudean, M.; Wessel, R.A.

    1998-08-01

    This project was initiated in October 1990, with the objective of developing and validating a new computer model of a recovery boiler furnace using a computational fluid dynamics (CFD) code specifically tailored to the requirements for solving recovery boiler flows, and using improved submodels for black liquor combustion based on continued laboratory fundamental studies. The key tasks to be accomplished were as follows: (1) Complete the development of enhanced furnace models that have the capability to accurately predict carryover, emissions behavior, dust concentrations, gas temperatures, and wall heat fluxes. (2) Validate the enhanced furnace models, so that users can have confidence in the predicted results. (3) Obtain fundamental information on aerosol formation, deposition, and hardening so as to develop the knowledge base needed to relate furnace model outputs to plugging and fouling in the convective sections of the boiler. (4) Facilitate the transfer of codes, black liquid submodels, and fundamental knowledge to the US kraft pulp industry. Volume 2 contains the last section of Appendix I, Radiative heat transfer in kraft recovery boilers, and the first section of Appendix II, The effect of temperature and residence time on the distribution of carbon, sulfur, and nitrogen between gaseous and condensed phase products from low temperature pyrolysis of kraft black liquor.

  17. Assessing Wildlife Habitat Value of New England Salt Marshes: II. Model Testing and Validation

    EPA Science Inventory

    We test a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. Assessment scores ranged f...

  18. The MicroArray Quality Control (MAQC)-II study of common practices for the development and validation of microarray-based predictive models

    EPA Science Inventory

    The second phase of the MicroArray Quality Control (MAQC-II) project evaluated common practices for developing and validating microarray-based models aimed at predicting toxicological and clinical endpoints. Thirty-six teams developed classifiers for 13 endpoints - some easy, som...

  19. TAMDAR Sensor Validation in 2003 AIRS II

    NASA Technical Reports Server (NTRS)

    Daniels, Taumi S.; Murray, John J.; Anderson, Mark V.; Mulally, Daniel J.; Jensen, Kristopher R.; Grainger, Cedric A.; Delene, David J.

    2005-01-01

    This study entails an assessment of TAMDAR in situ temperature, relative humidity and winds sensor data from seven flights of the UND Citation II. These data are undergoing rigorous assessment to determine their viability to significantly augment domestic Meteorological Data Communications Reporting System (MDCRS) and the international Aircraft Meteorological Data Reporting (AMDAR) system observational databases to improve the performance of regional and global numerical weather prediction models. NASA Langley Research Center participated in the Second Alliance Icing Research Study from November 17 to December 17, 2003. TAMDAR data taken during this period is compared with validation data from the UND Citation. The data indicate acceptable performance of the TAMDAR sensor when compared to measurements from the UND Citation research instruments.

  20. Model Validation Status Review

    SciTech Connect

    E.L. Hardin

    2001-11-28

    The primary objective for the Model Validation Status Review was to perform a one-time evaluation of model validation associated with the analysis/model reports (AMRs) containing model input to total-system performance assessment (TSPA) for the Yucca Mountain site recommendation (SR). This review was performed in response to Corrective Action Request BSC-01-C-01 (Clark 2001, Krisha 2001) pursuant to Quality Assurance review findings of an adverse trend in model validation deficiency. The review findings in this report provide the following information which defines the extent of model validation deficiency and the corrective action needed: (1) AMRs that contain or support models are identified, and conversely, for each model the supporting documentation is identified. (2) The use for each model is determined based on whether the output is used directly for TSPA-SR, or for screening (exclusion) of features, events, and processes (FEPs), and the nature of the model output. (3) Two approaches are used to evaluate the extent to which the validation for each model is compliant with AP-3.10Q (Analyses and Models). The approaches differ in regard to whether model validation is achieved within individual AMRs as originally intended, or whether model validation could be readily achieved by incorporating information from other sources. (4) Recommendations are presented for changes to the AMRs, and additional model development activities or data collection, that will remedy model validation review findings, in support of licensing activities. The Model Validation Status Review emphasized those AMRs that support TSPA-SR (CRWMS M&O 2000bl and 2000bm). A series of workshops and teleconferences was held to discuss and integrate the review findings. The review encompassed 125 AMRs (Table 1) plus certain other supporting documents and data needed to assess model validity. The AMRs were grouped in 21 model areas representing the modeling of processes affecting the natural and

  1. SOSS ICN Model Validation

    NASA Technical Reports Server (NTRS)

    Zhu, Zhifan

    2016-01-01

    Under the NASA-KAIA-KARI ATM research collaboration agreement, SOSS ICN Model has been developed for Incheon International Airport. This presentation describes the model validation work in the project. The presentation will show the results and analysis of the validation.

  2. Black liquor combustion validated recovery boiler modeling: Final year report. Volume 3 (Appendices II, sections 2--3 and III)

    SciTech Connect

    Grace, T.M.; Frederick, W.J.; Salcudean, M.; Wessel, R.A.

    1998-08-01

    This project was initiated in October 1990, with the objective of developing and validating a new computer model of a recovery boiler furnace using a computational fluid dynamics (CFD) code specifically tailored to the requirements for solving recovery boiler flows, and using improved submodels for black liquor combustion based on continued laboratory fundamental studies. The key tasks to be accomplished were as follows: (1) Complete the development of enhanced furnace models that have the capability to accurately predict carryover, emissions behavior, dust concentrations, gas temperatures, and wall heat fluxes. (2) Validate the enhanced furnace models, so that users can have confidence in the predicted results. (3) Obtain fundamental information on aerosol formation, deposition, and hardening so as to develop the knowledge base needed to relate furnace model outputs to plugging and fouling in the convective sections of the boiler. (4) Facilitate the transfer of codes, black liquid submodels, and fundamental knowledge to the US kraft pulp industry. Volume 3 contains the following appendix sections: Formation and destruction of nitrogen oxides in recovery boilers; Sintering and densification of recovery boiler deposits laboratory data and a rate model; and Experimental data on rates of particulate formation during char bed burning.

  3. Numerical investigation of dynamic microorgan devices as drug screening platforms. Part II: Microscale modeling approach and validation.

    PubMed

    Tourlomousis, Filippos; Chang, Robert C

    2016-03-01

    The authors have previously reported a rigorous macroscale modeling approach for an in vitro 3D dynamic microorgan device (DMD). This paper represents the second of a two-part model-based investigation where the effect of microscale (single liver cell-level) shear-mediated mechanotransduction on drug biotransformation is deconstructed. Herein, each cell is explicitly incorporated into the geometric model as single compartmentalized metabolic structures. Each cell's metabolic activity is coupled with the microscale hydrodynamic Wall Shear Stress (WSS) simulated around the cell boundary through a semi-empirical polynomial function as an additional reaction term in the mass transfer equations. Guided by the macroscale model-based hydrodynamics, only 9 cells in 3 representative DMD domains are explicitly modeled. Dynamic and reaction similarity rules based on non-dimensionalization are invoked to correlate the numerical and empirical models, accounting for the substrate time scales. The proposed modeling approach addresses the key challenge of computational cost towards modeling complex large-scale DMD-type system with prohibitively high cell densities. Transient simulations are implemented to extract the drug metabolite profile with the microscale modeling approach validated with an experimental drug flow study. The results from the author's study demonstrate the preferred implementation of the microscale modeling approach over that of its macroscale counterpart. PMID:26333066

  4. Macrotransport-solidification kinetics modeling of equiaxed dendritic growth: Part II. Computation problems and validation on INCONEL 718 superalloy castings

    NASA Astrophysics Data System (ADS)

    Nastac, L.; Stefanescu, D. M.

    1996-12-01

    In Part I of the article, a new analytical model that describes solidification of equiaxed dendrites was presented. In this part of the article, the model is used to simulate the solidification of INCONEL 718 superalloy castings. The model was incorporated into a commercial finite-element code, PROCAST. A special procedure called microlatent heat method (MLHM) was used for coupling between macroscopic heat flow and microscopic growth kinetics. A criterion for time-stepping selection in microscopic modeling has been derived in conjunction with MLHM. Reductions in computational (CPU) time up to 90 pct over the classic latent heat method were found by adopting this coupling. Validation of the model was performed against experimental data for an INCONEL 718 superalloy casting. In the present calculations, the model for globulitic dendrite was used. The evolution of fraction of solid calculated with the present model was compared with Scheil’s model and experiments. An important feature in solidification of INCONEL 718 is the detrimental Laves phase. Laves phase content is directly related to the intensity of microsegregation of niobium, which is very sensitive to the evolution of the fraction of solid. It was found that there is a critical cooling rate at which the amount of Laves phase is maximum. The critical cooling rate is not a function of material parameters (diffusivity, partition coefficient, etc.). It depends only on the grain size and solidification time. The predictions generated with the present model are shown to agree very well with experiments.

  5. Development of a new version of the Liverpool Malaria Model. II. Calibration and validation for West Africa

    PubMed Central

    2011-01-01

    Background In the first part of this study, an extensive literature survey led to the construction of a new version of the Liverpool Malaria Model (LMM). A new set of parameter settings was provided and a new development of the mathematical formulation of important processes related to the vector population was performed within the LMM. In this part of the study, so far undetermined model parameters are calibrated through the use of data from field studies. The latter are also used to validate the new LMM version, which is furthermore compared against the original LMM version. Methods For the calibration and validation of the LMM, numerous entomological and parasitological field observations were gathered for West Africa. Continuous and quality-controlled temperature and precipitation time series were constructed using intermittent raw data from 34 weather stations across West Africa. The meteorological time series served as the LMM data input. The skill of LMM simulations was tested for 830 different sets of parameter settings of the undetermined LMM parameters. The model version with the highest skill score in terms of entomological malaria variables was taken as the final setting of the new LMM version. Results Validation of the new LMM version in West Africa revealed that the simulations compare well with entomological field observations. The new version reproduces realistic transmission rates and simulated malaria seasons are comparable to field observations. Overall the new model version performs much better than the original model. The new model version enables the detection of the epidemic malaria potential at fringes of endemic areas and, more importantly, it is now applicable to the vast area of malaria endemicity in the humid African tropics. Conclusions A review of entomological and parasitological data from West Africa enabled the construction of a new LMM version. This model version represents a significant step forward in the modelling of a weather

  6. Validation of the European System for Cardiac Operative Risk Evaluation-II model in an urban Indian population and comparison with three other risk scoring systems

    PubMed Central

    Pillai, Biju Sivam; Baloria, Kanwar Aditya; Selot, Nandini

    2015-01-01

    Aims and Objectives: The aims were to compare the European System for Cardiac Operative Risk Evaluation (EuroSCORE)-II system against three established risk scoring systems for predictive accuracy in an urban Indian population and suggest improvements or amendments in the existing scoring system for adaptation in Indian population. Materials and Methods: EuroSCORE-II, Parsonnet score, System-97 score, and Cleveland score were obtained preoperatively for 1098 consecutive patients. EuroSCORE-II system was analyzed in comparison to each of the above three scoring systems in an urban Indian population. Calibrations of scoring systems were assessed using Hosmer–Lemeshow test. Areas under receiver operating characteristics (ROC) curves were compared according to the statistical approach suggested by Hanley and McNeil. Results: All EuroSCORE-II subgroups had highly significant P values stating good predictive mortality, except high-risk group (P = 0.175). The analysis of ROC curves of different scoring systems showed that the highest predictive value for mortality was calculated for the System-97 score followed by the Cleveland score. System-97 revealed extremely high predictive accuracies across all subgroups (curve area >80%). This difference in predictive accuracy was found to be statistically significant (P < 0.001). Conclusions: The present study suggests that the EuroSCORE-II model in its present form is not validated for use in the Indian population. An interesting observation was significantly accurate predictive abilities of the System-97 score. PMID:26139738

  7. Groundwater Model Validation

    SciTech Connect

    Ahmed E. Hassan

    2006-01-24

    Models have an inherent uncertainty. The difficulty in fully characterizing the subsurface environment makes uncertainty an integral component of groundwater flow and transport models, which dictates the need for continuous monitoring and improvement. Building and sustaining confidence in closure decisions and monitoring networks based on models of subsurface conditions require developing confidence in the models through an iterative process. The definition of model validation is postulated as a confidence building and long-term iterative process (Hassan, 2004a). Model validation should be viewed as a process not an end result. Following Hassan (2004b), an approach is proposed for the validation process of stochastic groundwater models. The approach is briefly summarized herein and detailed analyses of acceptance criteria for stochastic realizations and of using validation data to reduce input parameter uncertainty are presented and applied to two case studies. During the validation process for stochastic models, a question arises as to the sufficiency of the number of acceptable model realizations (in terms of conformity with validation data). Using a hierarchical approach to make this determination is proposed. This approach is based on computing five measures or metrics and following a decision tree to determine if a sufficient number of realizations attain satisfactory scores regarding how they represent the field data used for calibration (old) and used for validation (new). The first two of these measures are applied to hypothetical scenarios using the first case study and assuming field data consistent with the model or significantly different from the model results. In both cases it is shown how the two measures would lead to the appropriate decision about the model performance. Standard statistical tests are used to evaluate these measures with the results indicating they are appropriate measures for evaluating model realizations. The use of validation

  8. Comparison of Analytical Models of Propagation of CMEs and its Validation Using Type II Radio Bursts Observations

    NASA Astrophysics Data System (ADS)

    Perez Alanis, C. A.; Aguilar-Rodriguez, E.; Corona Romero, P.

    2015-12-01

    Coronal Mass Ejections (CMEs) are large-scale eruptive events arising from the solar corona that are expelled into the interplanetary (IP) medium. The CMEs can be associated with interplanetary shocks and this associated with type II radio-burst emissions. Some of the CMEs carry a magnetic configuration that can generate geomagnetic storm, the main interest in space weather. It is therefore important to predict arrival times of CMEs that are potential to generate a geomagnetic storm. We used a number of hydrodynamic (viscous and inertial) drag force models to approximate the trajectory of a CME. We focus on obtaining proportionality constants to achieve good approximations to CME arrivals. We analized a set of fast CMEs by finding the appropiate drag coefficients that simultaneusly approximated: the in-situ arrivals of the events, their associated type II radio-burst and satellite observations of these phenomena. Our results suggest that quadratic and inertial drag are the dynamic agent that prevails for fast CMEs propagation. Our studies may contribute to future 'space weather forescasting' at the Earth.

  9. Base Flow Model Validation

    NASA Technical Reports Server (NTRS)

    Sinha, Neeraj; Brinckman, Kevin; Jansen, Bernard; Seiner, John

    2011-01-01

    A method was developed of obtaining propulsive base flow data in both hot and cold jet environments, at Mach numbers and altitude of relevance to NASA launcher designs. The base flow data was used to perform computational fluid dynamics (CFD) turbulence model assessments of base flow predictive capabilities in order to provide increased confidence in base thermal and pressure load predictions obtained from computational modeling efforts. Predictive CFD analyses were used in the design of the experiments, available propulsive models were used to reduce program costs and increase success, and a wind tunnel facility was used. The data obtained allowed assessment of CFD/turbulence models in a complex flow environment, working within a building-block procedure to validation, where cold, non-reacting test data was first used for validation, followed by more complex reacting base flow validation.

  10. Validation of SAGE II NO2 measurements

    NASA Technical Reports Server (NTRS)

    Cunnold, D. M.; Zawodny, J. M.; Chu, W. P.; Mccormick, M. P.; Pommereau, J. P.; Goutail, F.

    1991-01-01

    The validity of NO2 measurements from the stratospheric aerosol and gas experiment (SAGE) II is examined by comparing the data with climatological distributions of NO2 and by examining the consistency of the observations themselves. The precision at high altitudes is found to be 5 percent, which is also the case at specific low altitudes for certain latitudes where the mixing ratio is 4 ppbv, and the precision is 0.2 ppbv at low altitudes. The autocorrelation distance of the smoothed profile measurement noise is 3-5 km and 10 km for 1-km and 5-km smoothing, respectively. The SAGE II measurements agree with spectroscopic measurements to within 10 percent, and the SAGE measurements are about 20 percent smaller than average limb monitor measurements at the mixing ratio peak. SAGE I and SAGE II measurements are slightly different, but the difference is not attributed to changes in atmospheric NO2.

  11. Validation of updated neutronic calculation models proposed for Atucha-II PHWR. Part II: Benchmark comparisons of PUMA core parameters with MCNP5 and improvements due to a simple cell heterogeneity correction

    SciTech Connect

    Grant, C.; Mollerach, R.; Leszczynski, F.; Serra, O.; Marconi, J.; Fink, J.

    2006-07-01

    In 2005 the Argentine Government took the decision to complete the construction of the Atucha-II nuclear power plant, which has been progressing slowly during the last ten years. Atucha-II is a 745 MWe nuclear station moderated and cooled with heavy water, of German (Siemens) design located in Argentina. It has a pressure vessel design with 451 vertical coolant channels and the fuel assemblies (FA) are clusters of 37 natural UO{sub 2} rods with an active length of 530 cm. For the reactor physics area, a revision and update of reactor physics calculation methods and models was recently carried out covering cell, supercell (control rod) and core calculations. This paper presents benchmark comparisons of core parameters of a slightly idealized model of the Atucha-I core obtained with the PUMA reactor code with MCNP5. The Atucha-I core was selected because it is smaller, similar from a neutronic point of view, more symmetric than Atucha-II, and has some experimental data available. To validate the new models benchmark comparisons of k-effective, channel power and axial power distributions obtained with PUMA and MCNP5 have been performed. In addition, a simple cell heterogeneity correction recently introduced in PUMA is presented, which improves significantly the agreement of calculated channel powers with MCNP5. To complete the validation, the calculation of some of the critical configurations of the Atucha-I reactor measured during the experiments performed at first criticality is also presented. (authors)

  12. Data Assimilation of Photosynthetic Light-use Efficiency using Multi-angular Satellite Data: II Model Implementation and Validation

    NASA Technical Reports Server (NTRS)

    Hilker, Thomas; Hall, Forest G.; Tucker, J.; Coops, Nicholas C.; Black, T. Andrew; Nichol, Caroline J.; Sellers, Piers J.; Barr, Alan; Hollinger, David Y.; Munger, J. W.

    2012-01-01

    Spatially explicit and temporally continuous estimates of photosynthesis will be of great importance for increasing our understanding of and ultimately closing the terrestrial carbon cycle. Current capabilities to model photosynthesis, however, are limited by accurate enough representations of the complexity of the underlying biochemical processes and the numerous environmental constraints imposed upon plant primary production. A potentially powerful alternative to model photosynthesis through these indirect observations is the use of multi-angular satellite data to infer light-use efficiency (e) directly from spectral reflectance properties in connection with canopy shadow fractions. Hall et al. (this issue) introduced a new approach for predicting gross ecosystem production that would allow the use of such observations in a data assimilation mode to obtain spatially explicit variations in e from infrequent polar-orbiting satellite observations, while meteorological data are used to account for the more dynamic responses of e to variations in environmental conditions caused by changes in weather and illumination. In this second part of the study we implement and validate the approach of Hall et al. (this issue) across an ecologically diverse array of eight flux-tower sites in North America using data acquired from the Compact High Resolution Imaging Spectroradiometer (CHRIS) and eddy-flux observations. Our results show significantly enhanced estimates of e and therefore cumulative gross ecosystem production (GEP) over the course of one year at all examined sites. We also demonstrate that e is greatly heterogeneous even across small study areas. Data assimilation and direct inference of GEP from space using a new, proposed sensor could therefore be a significant step towards closing the terrestrial carbon cycle.

  13. Applied model validation

    NASA Astrophysics Data System (ADS)

    Davies, A. D.

    1985-07-01

    The NBS Center for Fire Research (CFR) conducts scientific research bearing on the fire safety of buildings, vehicles, tunnels and other inhabited structures. Data from controlled fire experiments are collected, analyzed and reduced to the analytical formulas that appear to underly the observed phenomena. These results and more general physical principles are then combined into models to predict the development of environments that may be hostile to humans. This is a progress report of an applied model validation case study. The subject model is Transport of Fire, Smoke and Gases (FAST). Products from a fire in a burn room exit through a connected corridor to outdoors. Cooler counterflow air in a lower layer feeds the fire. The model predicts corridor layer temperatures and thicknesses vs. time, given enclosure, fire and ambient specifications. Data have been collected from 38 tests using several fire sizes, but have not been reduced. Corresponding model results, and model and test documentation are yet to come. Considerable modeling and calculation is needed to convert instrument readings to test results comparable with model outputs so that residual differences may be determined.

  14. Validation Studies for the Diet History Questionnaire II

    Cancer.gov

    Data show that the DHQ I instrument provides reasonable nutrient estimates, and three studies were conducted to assess its validity/calibration. There have been no such validation studies with the DHQ II.

  15. Ab initio structural modeling of and experimental validation for Chlamydia trachomatis protein CT296 reveal structural similarity to Fe(II) 2-oxoglutarate-dependent enzymes

    SciTech Connect

    Kemege, Kyle E.; Hickey, John M.; Lovell, Scott; Battaile, Kevin P.; Zhang, Yang; Hefty, P. Scott

    2012-02-13

    Chlamydia trachomatis is a medically important pathogen that encodes a relatively high percentage of proteins with unknown function. The three-dimensional structure of a protein can be very informative regarding the protein's functional characteristics; however, determining protein structures experimentally can be very challenging. Computational methods that model protein structures with sufficient accuracy to facilitate functional studies have had notable successes. To evaluate the accuracy and potential impact of computational protein structure modeling of hypothetical proteins encoded by Chlamydia, a successful computational method termed I-TASSER was utilized to model the three-dimensional structure of a hypothetical protein encoded by open reading frame (ORF) CT296. CT296 has been reported to exhibit functional properties of a divalent cation transcription repressor (DcrA), with similarity to the Escherichia coli iron-responsive transcriptional repressor, Fur. Unexpectedly, the I-TASSER model of CT296 exhibited no structural similarity to any DNA-interacting proteins or motifs. To validate the I-TASSER-generated model, the structure of CT296 was solved experimentally using X-ray crystallography. Impressively, the ab initio I-TASSER-generated model closely matched (2.72-{angstrom} C{alpha} root mean square deviation [RMSD]) the high-resolution (1.8-{angstrom}) crystal structure of CT296. Modeled and experimentally determined structures of CT296 share structural characteristics of non-heme Fe(II) 2-oxoglutarate-dependent enzymes, although key enzymatic residues are not conserved, suggesting a unique biochemical process is likely associated with CT296 function. Additionally, functional analyses did not support prior reports that CT296 has properties shared with divalent cation repressors such as Fur.

  16. Ecological reality and model validation

    SciTech Connect

    Cale, Jr, W. G.; Shugart, H. H.

    1980-01-01

    Definitions of model realism and model validation are developed. Ecological and mathematical arguments are then presented to show that model equations which explicitly treat ecosystem processes can be systematically improved such that greater realism is attained and the condition of validity is approached. Several examples are presented.

  17. A musculoskeletal model of the equine forelimb for determining surface stresses and strains in the humerus-part II. Experimental testing and model validation.

    PubMed

    Pollock, Sarah; Stover, Susan M; Hull, M L; Galuppo, Larry D

    2008-08-01

    The first objective of this study was to experimentally determine surface bone strain magnitudes and directions at the donor site for bone grafts, the site predisposed to stress fracture, the medial and cranial aspects of the transverse cross section corresponding to the stress fracture site, and the middle of the diaphysis of the humerus of a simplified in vitro laboratory preparation. The second objective was to determine whether computing strains solely in the direction of the longitudinal axis of the humerus in the mathematical model was inherently limited by comparing the strains measured along the longitudinal axis of the bone to the principal strain magnitudes and directions. The final objective was to determine whether the mathematical model formulated in Part I [Pollock et al., 2008, ASME J. Biomech. Eng., 130, p. 041006] is valid for determining the bone surface strains at the various locations on the humerus where experimentally measured longitudinal strains are comparable to principal strains. Triple rosette strain gauges were applied at four locations circumferentially on each of two cross sections of interest using a simplified in vitro laboratory preparation. The muscles included the biceps brachii muscle in addition to loaded shoulder muscles that were predicted active by the mathematical model. Strains from the middle grid of each rosette, aligned along the longitudinal axis of the humerus, were compared with calculated principal strain magnitudes and directions. The results indicated that calculating strains solely in the direction of the longitudinal axis is appropriate at six of eight locations. At the cranial and medial aspects of the middle of the diaphysis, the average minimum principal strain was not comparable to the average experimental longitudinal strain. Further analysis at the remaining six locations indicated that the mathematical model formulated in Part I predicts strains within +/-2 standard deviations of experimental strains at

  18. Validation of SAGE II ozone measurements

    NASA Technical Reports Server (NTRS)

    Cunnold, D. M.; Chu, W. P.; Mccormick, M. P.; Veiga, R. E.; Barnes, R. A.

    1989-01-01

    Five ozone profiles from the Stratospheric Aerosol and Gas Experiment (SAGE) II are compared with coincident ozonesonde measurements obtained at Natal, Brazil, and Wallops Island, Virginia. It is shown that the mean difference between all of the measurements is about 1 percent and that the agreement is within 7 percent at altitudes between 20 and 53 km. Good agreement is also found for ozone mixing ratios on pressure surfaces. It is concluded that the SAGE II profiles provide useful ozone information up to about 60 km altitude.

  19. SAGE II aerosol validation - Selected altitude measurements, including particle micromeasurements

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Russell, Philip B.; Pueschel, Rudolf F.; Snetsinger, Kenneth G.; Ferry, Guy V.; Livingston, John M.; Rosen, James N.; Osborn, Mary T.; Kritz, Mark A.

    1989-01-01

    The validity of particulate extinction coefficients derived from limb path solar radiance measurements obtained during the Stratospheric Aerosol and Gas Experiment (SAGE) II is tested. The SAGE II measurements are compared with correlative aerosol measurements taken during January 1985, August 1985, and July 1986 with impactors, laser spectrometers, and filter samplers on a U-2 aircraft, an upward pointing lidar on a P-3 aircraft, and balloon-borne optical particle counters. The data for July 29, 1986 are discussed in detail. The aerosol measurements taken on this day at an altitude of 20.5 km produce particulate extinction values which validate the SAGE II values for similar wavelengths.

  20. Validation of mesoscale models

    NASA Technical Reports Server (NTRS)

    Kuo, Bill; Warner, Tom; Benjamin, Stan; Koch, Steve; Staniforth, Andrew

    1993-01-01

    The topics discussed include the following: verification of cloud prediction from the PSU/NCAR mesoscale model; results form MAPS/NGM verification comparisons and MAPS observation sensitivity tests to ACARS and profiler data; systematic errors and mesoscale verification for a mesoscale model; and the COMPARE Project and the CME.

  1. ON PREDICTION AND MODEL VALIDATION

    SciTech Connect

    M. MCKAY; R. BECKMAN; K. CAMPBELL

    2001-02-01

    Quantification of prediction uncertainty is an important consideration when using mathematical models of physical systems. This paper proposes a way to incorporate ''validation data'' in a methodology for quantifying uncertainty of the mathematical predictions. The report outlines a theoretical framework.

  2. Cross-Validation of the JSORRAT-II in Iowa.

    PubMed

    Ralston, Christopher A; Epperson, Douglas L; Edwards, Sarah R

    2016-09-01

    The predictive validity of the Juvenile Sexual Offense Recidivism Risk Assessment Tool-II (JSORRAT-II) was evaluated using an exhaustive sample of 11- to 17-year-old male juveniles who offended sexually (JSOs) between 2000 and 2006 in Iowa (n = 529). The validity of the tool in predicting juvenile sexual recidivism was significant (area under the receiver operating characteristic curve [AUC] = .70, 99% confidence interval [CI] = [.60, .81], d = 0.70). Non-significant predictive validity coefficients were observed for the prediction of non-sexual forms of recidivism. Additional analyses were undertaken to test hypotheses about the tool's performance with various subsamples. The age of the JSO at the time of the index sexual offense and time at risk outside secure facility placements interacted significantly with JSORRAT-II scores to predict juvenile sexual recidivism. The implications of these findings for practice and research on the validation of risk assessment tools are discussed. PMID:25179400

  3. TUTORIAL: Validating biorobotic models

    NASA Astrophysics Data System (ADS)

    Webb, Barbara

    2006-09-01

    Some issues in neuroscience can be addressed by building robot models of biological sensorimotor systems. What we can conclude from building models or simulations, however, is determined by a number of factors in addition to the central hypothesis we intend to test. These include the way in which the hypothesis is represented and implemented in simulation, how the simulation output is interpreted, how it is compared to the behaviour of the biological system, and the conditions under which it is tested. These issues will be illustrated by discussing a series of robot models of cricket phonotaxis behaviour. .

  4. Partial Validation of Multibody Program to Optimize Simulated Trajectories II (POST II) Parachute Simulation With Interacting Forces

    NASA Technical Reports Server (NTRS)

    Raiszadeh, Ben; Queen, Eric M.

    2002-01-01

    A capability to simulate trajectories Of Multiple interacting rigid bodies has been developed. This capability uses the Program to Optimize Simulated Trajectories II (POST II). Previously, POST II had the ability to simulate multiple bodies without interacting forces. The current implementation is used for the Simulation of parachute trajectories, in which the parachute and suspended bodies can be treated as rigid bodies. An arbitrary set of connecting lines can be included in the model and are treated as massless spring-dampers. This paper discusses details of the connection line modeling and results of several test cases used to validate the capability.

  5. A dynamic model of some malaria-transmitting anopheline mosquitoes of the Afrotropical region. II. Validation of species distribution and seasonal variations

    PubMed Central

    2013-01-01

    Background The first part of this study aimed to develop a model for Anopheles gambiae s.l. with separate parametrization schemes for Anopheles gambiae s.s. and Anopheles arabiensis. The characterizations were constructed based on literature from the past decades. This part of the study is focusing on the model’s ability to separate the mean state of the two species of the An. gambiae complex in Africa. The model is also evaluated with respect to capturing the temporal variability of An. arabiensis in Ethiopia. Before conclusions and guidance based on models can be made, models need to be validated. Methods The model used in this paper is described in part one (Malaria Journal 2013, 12:28). For the validation of the model, a data base of 5,935 points on the presence of An. gambiae s.s. and An. arabiensis was constructed. An additional 992 points were collected on the presence An. gambiae s.l.. These data were used to assess if the model could recreate the spatial distribution of the two species. The dataset is made available in the public domain. This is followed by a case study from Madagascar where the model’s ability to recreate the relative fraction of each species is investigated. In the last section the model’s ability to reproduce the temporal variability of An. arabiensis in Ethiopia is tested. The model was compared with data from four papers, and one field survey covering two years. Results Overall, the model has a realistic representation of seasonal and year to year variability in mosquito densities in Ethiopia. The model is also able to describe the distribution of An. gambiae s.s. and An. arabiensis in sub-Saharan Africa. This implies this model can be used for seasonal and long term predictions of changes in the burden of malaria. Before models can be used to improving human health, or guide which interventions are to be applied where, there is a need to understand the system of interest. Validation is an important part of this process. It is

  6. Benchmark Energetic Data in a Model System for Grubbs II Metathesis Catalysis and Their Use for the Development, Assessment, and Validation of Electronic Structure Methods

    SciTech Connect

    Zhao, Yan; Truhlar, Donald G.

    2009-01-31

    We present benchmark relative energetics in the catalytic cycle of a model system for Grubbs second-generation olefin metathesis catalysts. The benchmark data were determined by a composite approach based on CCSD(T) calculations, and they were used as a training set to develop a new spin-component-scaled MP2 method optimized for catalysis, which is called SCSC-MP2. The SCSC-MP2 method has improved performance for modeling Grubbs II olefin metathesis catalysts as compared to canonical MP2 or SCS-MP2. We also employed the benchmark data to test 17 WFT methods and 39 density functionals. Among the tested density functionals, M06 is the best performing functional. M06/TZQS gives an MUE of only 1.06 kcal/mol, and it is a much more affordable method than the SCSC-MP2 method or any other correlated WFT methods. The best performing meta-GGA is M06-L, and M06-L/DZQ gives an MUE of 1.77 kcal/mol. PBEh is the best performing hybrid GGA, with an MUE of 3.01 kcal/mol; however, it does not perform well for the larger, real Grubbs II catalyst. B3LYP and many other functionals containing the LYP correlation functional perform poorly, and B3LYP underestimates the stability of stationary points for the cis-pathway of the model system by a large margin. From the assessments, we recommend the M06, M06-L, and MPW1B95 functionals for modeling Grubbs II olefin metathesis catalysts. The local M06-L method is especially efficient for calculations on large systems.

  7. Uncertainty Modeling Via Frequency Domain Model Validation

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Andrisani, Dominick, II

    1999-01-01

    Abstract The majority of literature on robust control assumes that a design model is available and that the uncertainty model bounds the actual variations about the nominal model. However, methods for generating accurate design models have not received as much attention in the literature. The influence of the level of accuracy of the uncertainty model on closed loop performance has received even less attention. The research reported herein is an initial step in applying and extending the concept of model validation to the problem of obtaining practical uncertainty models for robust control analysis and design applications. An extension of model validation called 'sequential validation' is presented and applied to a simple spring-mass-damper system to establish the feasibility of the approach and demonstrate the benefits of the new developments.

  8. Statistical validation of system models

    SciTech Connect

    Barney, P.; Ferregut, C.; Perez, L.E.; Hunter, N.F.; Paez, T.L.

    1997-01-01

    It is common practice in system analysis to develop mathematical models for system behavior. Frequently, the actual system being modeled is also available for testing and observation, and sometimes the test data are used to help identify the parameters of the mathematical model. However, no general-purpose technique exists for formally, statistically judging the quality of a model. This paper suggests a formal statistical procedure for the validation of mathematical models of systems when data taken during operation of the system are available. The statistical validation procedure is based on the bootstrap, and it seeks to build a framework where a statistical test of hypothesis can be run to determine whether or not a mathematical model is an acceptable model of a system with regard to user-specified measures of system behavior. The approach to model validation developed in this study uses experimental data to estimate the marginal and joint confidence intervals of statistics of interest of the system. These same measures of behavior are estimated for the mathematical model. The statistics of interest from the mathematical model are located relative to the confidence intervals for the statistics obtained from the experimental data. These relative locations are used to judge the accuracy of the mathematical model. An extension of the technique is also suggested, wherein randomness may be included in the mathematical model through the introduction of random variable and random process terms. These terms cause random system behavior that can be compared to the randomness in the bootstrap evaluation of experimental system behavior. In this framework, the stochastic mathematical model can be evaluated. A numerical example is presented to demonstrate the application of the technique.

  9. Turbulence Modeling Verification and Validation

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.

    2014-01-01

    Computational fluid dynamics (CFD) software that solves the Reynolds-averaged Navier-Stokes (RANS) equations has been in routine use for more than a quarter of a century. It is currently employed not only for basic research in fluid dynamics, but also for the analysis and design processes in many industries worldwide, including aerospace, automotive, power generation, chemical manufacturing, polymer processing, and petroleum exploration. A key feature of RANS CFD is the turbulence model. Because the RANS equations are unclosed, a model is necessary to describe the effects of the turbulence on the mean flow, through the Reynolds stress terms. The turbulence model is one of the largest sources of uncertainty in RANS CFD, and most models are known to be flawed in one way or another. Alternative methods such as direct numerical simulations (DNS) and large eddy simulations (LES) rely less on modeling and hence include more physics than RANS. In DNS all turbulent scales are resolved, and in LES the large scales are resolved and the effects of the smallest turbulence scales are modeled. However, both DNS and LES are too expensive for most routine industrial usage on today's computers. Hybrid RANS-LES, which blends RANS near walls with LES away from walls, helps to moderate the cost while still retaining some of the scale-resolving capability of LES, but for some applications it can still be too expensive. Even considering its associated uncertainties, RANS turbulence modeling has proved to be very useful for a wide variety of applications. For example, in the aerospace field, many RANS models are considered to be reliable for computing attached flows. However, existing turbulence models are known to be inaccurate for many flows involving separation. Research has been ongoing for decades in an attempt to improve turbulence models for separated and other nonequilibrium flows. When developing or improving turbulence models, both verification and validation are important

  10. MODEL VALIDATION REPORT FOR THE HOUSATONIC RIVER

    EPA Science Inventory

    The Model Validation Report will present a comparison of model validation runs to existing data for the model validation period. The validation period spans a twenty year time span to test the predictive capability of the model over a longer time period, similar to that which wil...

  11. Validity and Reliability of Health Promoting Lifestyle Profile II in the Iranian Elderly

    PubMed Central

    Tanjani, Parisa Taheri; Azadbakht, Mojtaba; Garmaroudi, Gholamreza; Sahaf, Robab; Fekrizadeh, Zohreh

    2016-01-01

    Background: With increasing age, the prevalence of chronic diseases increases. Since health-promoting behaviors (HPB) are considered a basic way of preventing diseases, especially chronic diseases, it is important to assess HPB. This study examines the validity and reliability of the Health Promoting Lifestyle Profile II (HPLP-II). Methods: This is a cross-sectional study which is conducted on 502 elderly individuals aged 60 and over in Tehran, Iran. In order to determine the validity, content and construct validity were used. The content validity index (CVI) was used to assess the content validity and to assess construct validity, confirmatory factor analysis (CFA), and item-total correlations were employed. For reliability, test-retest analysis was used, and the internal consistency of the HPLP-II was confirmed by Cronbach's alpha. For data analysis, SPSS-18 and Amos-7 software was used. Results: The mean age of the subjects was 66.3 ± 5.3 years. The CVI for the revised HPLP-II and all its subscales was higher than 0.82. The CFA confirmed a six-factor model aligned with the original HPLP-II. Pearson correlation coefficients between the revised HPLP-II and their items were in range of 0.27–0.65. Cronbach's alpha of the revised HPLP-II was obtained as 0.78 and for their subscales were in the range of 0.67–0.84. Intraclass correlation coefficient was obtained 0.79 (95% confidence interval: 0.59–0.86, P < 0.001). Conclusions: The Iranian HPLP-II scale is an appropriate tool for assessing HPBs of the Iranian elderly. PMID:27280010

  12. ADAPT model: Model use, calibration and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper presents an overview of the Agricultural Drainage and Pesticide Transport (ADAPT) model and a case study to illustrate the calibration and validation steps for predicting subsurface tile drainage and nitrate-N losses from an agricultural system. The ADAPT model is a daily time step field ...

  13. (Validity of environmental transfer models)

    SciTech Connect

    Blaylock, B.G.; Hoffman, F.O.; Gardner, R.H.

    1990-11-07

    BIOMOVS (BIOspheric MOdel Validation Study) is an international cooperative study initiated in 1985 by the Swedish National Institute of Radiation Protection to test models designed to calculate the environmental transfer and bioaccumulation of radionuclides and other trace substances. The objective of the symposium and workshop was to synthesize results obtained during Phase 1 of BIOMOVS (the first five years of the study) and to suggest new directions that might be pursued during Phase 2 of BIOMOVS. The travelers were an instrumental part of the development of BIOMOVS. This symposium allowed the travelers to present a review of past efforts at model validation and a synthesis of current activities and to refine ideas concerning future development of models and data for assessing the fate, effect, and human risks of environmental contaminants. R. H. Gardner also visited the Free University, Amsterdam, and the National Institute of Public Health and Environmental Protection (RIVM) in Bilthoven to confer with scientists about current research in theoretical ecology and the use of models for estimating the transport and effect of environmental contaminants and to learn about the European efforts to map critical loads of acid deposition.

  14. Proposed Modifications to the Conceptual Model of Coaching Efficacy and Additional Validity Evidence for the Coaching Efficacy Scale II-High School Teams

    ERIC Educational Resources Information Center

    Myers, Nicholas; Feltz, Deborah; Chase, Melissa

    2011-01-01

    The purpose of this study was to determine whether theoretically relevant sources of coaching efficacy could predict the measures derived from the Coaching Efficacy Scale II-High School Teams (CES II-HST). Data were collected from head coaches of high school teams in the United States (N = 799). The analytic framework was a multiple-group…

  15. Atlas II and IIA analyses and environments validation

    NASA Astrophysics Data System (ADS)

    Martin, Richard E.

    1995-06-01

    General Dynamics has now flown all four versions of the Atlas commercial launch vehicle, which cover a payload weight capability to geosynchronous transfer orbit (GTO) in the range of 5000-8000 lb. The key analyses to set design and environmental test parameters for the vehicle modifications and the ground and flight test data that validated them were prepared in paper IAF-91-170 for the first version, Atlas I. This paper presents similar data for the next two versions, Atlas II and IIA. The Atlas II has propellant tanks lengthened by 12 ft and is boosted by MA-5A rocket engines uprated to 474,000 lb liftoff thrust. GTO payload capability is 6225 lb with the 11-ft fairing. The Atlas IIA is an Atlas II with uprated RL10A-4 engines on the lengthened Centaur II upper stage. The two 20,800 lb thrust, 449 s specific impulse engines with an optional extendible nozzle increase payload capability to GTO to 6635 lb. The paper describes design parameters and validated test results for many other improvements that have generally provided greater capability at less cost, weight and complexity and better reliability. Those described include: moving the MA-5A start system to the ground, replacing the vernier engines with a simple 50 lb thrust on-off hydrazine roll control system, addition of a POGO suppressor, replacement of Centaur jettisonable insulation panels with fixed foam, a new inertial navigation unit (INU) that combines in one package a ring-laser gyro based strapdown guidance system with two MIL-STD-1750A processors, redundant MIL-STD-1553 data bus interfaces, robust Ada-based software and a new Al-Li payload adapter. Payload environment is shown to be essentially unchanged from previous Atlas vehicles. Validation of load, stability, control and pressurization requirements for the larger vehicle is discussed. All flights to date (five Atlas II, one Atlas IIA) have been successful in launching satellites for EUTELSAT, the U.S. Air Force and INTELSAT. Significant design

  16. Validation of Magnetospheric Magnetohydrodynamic Models

    NASA Astrophysics Data System (ADS)

    Curtis, Brian

    Magnetospheric magnetohydrodynamic (MHD) models are commonly used for both prediction and modeling of Earth's magnetosphere. To date, very little validation has been performed to determine their limits, uncertainties, and differences. In this work, we performed a comprehensive analysis using several commonly used validation techniques in the atmospheric sciences to MHD-based models of Earth's magnetosphere for the first time. The validation techniques of parameter variability/sensitivity analysis and comparison to other models were used on the OpenGGCM, BATS-R-US, and SWMF magnetospheric MHD models to answer several questions about how these models compare. The questions include: (1) the difference between the model's predictions prior to and following to a reversal of Bz in the upstream interplanetary field (IMF) from positive to negative, (2) the influence of the preconditioning duration, and (3) the differences between models under extreme solar wind conditions. A differencing visualization tool was developed and used to address these three questions. We find: (1) For a reversal in IMF Bz from positive to negative, the OpenGGCM magnetopause is closest to Earth as it has the weakest magnetic pressure near-Earth. The differences in magnetopause positions between BATS-R-US and SWMF are explained by the influence of the ring current, which is included in SWMF. Densities are highest for SWMF and lowest for OpenGGCM. The OpenGGCM tail currents differ significantly from BATS-R-US and SWMF; (2) A longer preconditioning time allowed the magnetosphere to relax more, giving different positions for the magnetopause with all three models before the IMF Bz reversal. There were differences greater than 100% for all three models before the IMF Bz reversal. The differences in the current sheet region for the OpenGGCM were small after the IMF Bz reversal. The BATS-R-US and SWMF differences decreased after the IMF Bz reversal to near zero; (3) For extreme conditions in the solar

  17. Assimilation of Geosat Altimetric Data in a Nonlinear Shallow-Water Model of the Indian Ocean by Adjoint Approach. Part II: Some Validation and Interpretation of the Assimilated Results. Part 2; Some Validation and Interpretation of the Assimilated Results

    NASA Technical Reports Server (NTRS)

    Greiner, Eric; Perigaud, Claire

    1996-01-01

    This paper examines the results of assimilating Geosat sea level variations relative to the November 1986-November 1988 mean reference, in a nonlinear reduced-gravity model of the Indian Ocean, Data have been assimilated during one year starting in November 1986 with the objective of optimizing the initial conditions and the yearly averaged reference surface. The thermocline slope simulated by the model with or without assimilation is validated by comparison with the signal, which can be derived from expandable bathythermograph measurements performed in the Indian Ocean at that time. The topography simulated with assimilation on November 1986 is in very good agreement with the hydrographic data. The slopes corresponding to the South Equatorial Current and to the South Equatorial Countercurrent are better reproduced with assimilation than without during the first nine months. The whole circulation of the cyclonic gyre south of the equator is then strongly intensified by assimilation. Another assimilation experiment is run over the following year starting in November 1987. The difference between the two yearly mean surfaces simulated with assimilation is in excellent agreement with Geosat. In the southeastern Indian Ocean, the correction to the yearly mean dynamic topography due to assimilation over the second year is negatively correlated to the one the year before. This correction is also in agreement with hydrographic data. It is likely that the signal corrected by assimilation is not only due to wind error, because simulations driven by various wind forcings present the same features over the two years. Model simulations run with a prescribed throughflow transport anomaly indicate that assimilation is rather correcting in the interior of the model domain for inadequate boundary conditions with the Pacific.

  18. SRVAL. Stock-Recruitment Model VALidation Code

    SciTech Connect

    Christensen, S.W.

    1989-12-07

    SRVAL is a computer simulation model of the Hudson River striped bass population. It was designed to aid in assessing the validity of curve-fits of the linearized Ricker stock-recruitment model, modified to incorporate multiple-age spawners and to include an environmental variable, to variously processed annual catch-per-unit-effort (CPUE) statistics for a fish population. It is sometimes asserted that curve-fits of this kind can be used to determine the sensitivity of fish populations to such man-induced stresses as entrainment and impingement at power plants. SRVAL was developed to test such assertions and was utilized in testimony written in connection with the Hudson River Power Case (U. S. Environmental Protection Agency, Region II).

  19. A statistical-dynamical scheme for reconstructing ocean forcing in the Atlantic. Part II: methodology, validation and application to high-resolution ocean models

    NASA Astrophysics Data System (ADS)

    Minvielle, Marie; Cassou, Christophe; Bourdallé-Badie, Romain; Terray, Laurent; Najac, Julien

    2011-02-01

    A novel statistical-dynamical scheme has been developed to reconstruct the sea surface atmospheric variables necessary to force an ocean model. Multiple linear regressions are first built over a so-called learning period and over the entire Atlantic basin from the observed relationship between the surface wind conditions, or predictands, and the anomalous large scale atmospheric circulations, or predictors. The latter are estimated in the extratropics by 500 hPa geopotential height weather regimes and in the tropics by low-level wind classes. The transfer function further combined to an analog step is then used to reconstruct all the surface variables fields over 1958-2002. We show that the proposed hybrid scheme is very skillful in reproducing the mean state, the seasonal cycle and the temporal evolution of all the surface ocean variables at interannual timescale. Deficiencies are found in the level of variance especially in the tropics. It is underestimated for 2-m temperature and humidity as well as for surface radiative fluxes in the interannual frequency band while it is slightly overestimated at higher frequency. Decomposition in empirical orthogonal function (EOF) shows that the spatial and temporal coherence of the forcing fields is however very well captured by the reconstruction method. For dynamical downscaling purposes, reconstructed fields are then interpolated and used to carry out a high-resolution oceanic simulation using the NATL4 (1/4°) model integrated over 1979-2001. This simulation is compared to a reference experiment where the original observed forcing fields are prescribed instead. Mean states between the two experiments are virtually undistinguishable both in terms of surface fluxes and ocean dynamics estimated by the barotropic and the meridional overturning streamfunctions. The 3-dimensional variance of the simulated ocean is well preserved at interannual timescale both for temperature and salinity except in the tropics where it is

  20. Developing better and more valid animal models of brain disorders.

    PubMed

    Stewart, Adam Michael; Kalueff, Allan V

    2015-01-01

    Valid sensitive animal models are crucial for understanding the pathobiology of complex human disorders, such as anxiety, autism, depression and schizophrenia, which all have the 'spectrum' nature. Discussing new important strategic directions of research in this field, here we focus i) on cross-species validation of animal models, ii) ensuring their population (external) validity, and iii) the need to target the interplay between multiple disordered domains. We note that optimal animal models of brain disorders should target evolutionary conserved 'core' traits/domains and specifically mimic the clinically relevant inter-relationships between these domains. PMID:24384129

  1. Software Validation via Model Animation

    NASA Technical Reports Server (NTRS)

    Dutle, Aaron M.; Munoz, Cesar A.; Narkawicz, Anthony J.; Butler, Ricky W.

    2015-01-01

    This paper explores a new approach to validating software implementations that have been produced from formally-verified algorithms. Although visual inspection gives some confidence that the implementations faithfully reflect the formal models, it does not provide complete assurance that the software is correct. The proposed approach, which is based on animation of formal specifications, compares the outputs computed by the software implementations on a given suite of input values to the outputs computed by the formal models on the same inputs, and determines if they are equal up to a given tolerance. The approach is illustrated on a prototype air traffic management system that computes simple kinematic trajectories for aircraft. Proofs for the mathematical models of the system's algorithms are carried out in the Prototype Verification System (PVS). The animation tool PVSio is used to evaluate the formal models on a set of randomly generated test cases. Output values computed by PVSio are compared against output values computed by the actual software. This comparison improves the assurance that the translation from formal models to code is faithful and that, for example, floating point errors do not greatly affect correctness and safety properties.

  2. Preparation of Power Distribution System for High Penetration of Renewable Energy Part I. Dynamic Voltage Restorer for Voltage Regulation Pat II. Distribution Circuit Modeling and Validation

    NASA Astrophysics Data System (ADS)

    Khoshkbar Sadigh, Arash

    and the power rating for loads, is presented to prioritize which loads, lines and cables the meters should be installed at to have the most effect on model validation.

  3. Factor structure and construct validity of the Behavioral Dyscontrol Scale-II.

    PubMed

    Shura, Robert D; Rowland, Jared A; Yoash-Gantz, Ruth E

    2015-01-01

    The Behavioral Dyscontrol Scale-II (BDS-II) was developed as an improved scoring method to the original BDS, which was designed to evaluate the capacity for independent regulation of behavior and attention. The purpose of this study was to evaluate the factor structure and construct validity of the BDS-II, which had not been adequately re-examined since the development of the new scoring system. In a sample of 164 Veterans with a mean age of 35 years, exploratory factor analysis was used to evaluate BDS-II latent factor structure. Correlations and regressions were used to explore validity against 22 psychometrically sound neurocognitive measures across seven neurocognitive domains of sensation, motor output, processing speed, attention, visual-spatial reasoning, memory, and executive functions. Factor analysis found a two-factor solution for this sample which explained 41% of the variance in the model. Validity analyses found significant correlations among the BDS-II scores and all other cognitive domains except sensation and language (which was not evaluated). Hierarchical regressions revealed that PASAT performance was strongly associated with all three BDS-II scores; dominant hand Finger Tapping Test was also associated with the Total score and Factor 1, and CPT-II Commissions was also associated with Factor 2. These results suggest the BDS-II is both a general test of cerebral functioning, and a more specific test of working memory, motor output, and impulsivity. The BDS-II may therefore show utility with younger populations for measuring frontal lobe abilities and might be very sensitive to neurological injury. PMID:25650736

  4. Inert doublet model and LEP II limits

    SciTech Connect

    Lundstroem, Erik; Gustafsson, Michael; Edsjoe, Joakim

    2009-02-01

    The inert doublet model is a minimal extension of the standard model introducing an additional SU(2) doublet with new scalar particles that could be produced at accelerators. While there exists no LEP II analysis dedicated for these inert scalars, the absence of a signal within searches for supersymmetric neutralinos can be used to constrain the inert doublet model. This translation however requires some care because of the different properties of the inert scalars and the neutralinos. We investigate what restrictions an existing DELPHI Collaboration study of neutralino pair production can put on the inert scalars and discuss the result in connection with dark matter. We find that although an important part of the inert doublet model parameter space can be excluded by the LEP II data, the lightest inert particle still constitutes a valid dark matter candidate.

  5. SAGE II aerosol data validation and initial data use - An introduction and overview

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1989-01-01

    The process of validating data from the Stratospheric Aerosol and Gas Experiment (SAGE) II and the initial use of the validated data are reviewed. The instruments developed for the SAGE II, the influence of the eruption of El Chichon on the global stratospheric aerosol, and various data validation experiments are discussed. Consideration is given to methods for deriving aerosol physical and optical properties from SAGE II extinction data and for inferring particle size distribution moments from SAGE II spectral extinction values.

  6. Geochemistry Model Validation Report: External Accumulation Model

    SciTech Connect

    K. Zarrabi

    2001-09-27

    The purpose of this Analysis and Modeling Report (AMR) is to validate the External Accumulation Model that predicts accumulation of fissile materials in fractures and lithophysae in the rock beneath a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. (Lithophysae are voids in the rock having concentric shells of finely crystalline alkali feldspar, quartz, and other materials that were formed due to entrapped gas that later escaped, DOE 1998, p. A-25.) The intended use of this model is to estimate the quantities of external accumulation of fissile material for use in external criticality risk assessments for different types of degrading WPs: U.S. Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The scope of the model validation is to (1) describe the model and the parameters used to develop the model, (2) provide rationale for selection of the parameters by comparisons with measured values, and (3) demonstrate that the parameters chosen are the most conservative selection for external criticality risk calculations. To demonstrate the applicability of the model, a Pu-ceramic WP is used as an example. The model begins with a source term from separately documented EQ6 calculations; where the source term is defined as the composition versus time of the water flowing out of a breached waste package (WP). Next, PHREEQC, is used to simulate the transport and interaction of the source term with the resident water and fractured tuff below the repository. In these simulations the primary mechanism for accumulation is mixing of the high pH, actinide-laden source term with resident water; thus lowering the pH values sufficiently for fissile minerals to become insoluble and precipitate. In the final section of the model, the outputs from PHREEQC, are processed to produce mass of accumulation

  7. Validation of Multibody Program to Optimize Simulated Trajectories II Parachute Simulation with Interacting Forces

    NASA Technical Reports Server (NTRS)

    Raiszadeh, Behzad; Queen, Eric M.; Hotchko, Nathaniel J.

    2009-01-01

    A capability to simulate trajectories of multiple interacting rigid bodies has been developed, tested and validated. This capability uses the Program to Optimize Simulated Trajectories II (POST 2). The standard version of POST 2 allows trajectory simulation of multiple bodies without force interaction. In the current implementation, the force interaction between the parachute and the suspended bodies has been modeled using flexible lines, allowing accurate trajectory simulation of the individual bodies in flight. The POST 2 multibody capability is intended to be general purpose and applicable to any parachute entry trajectory simulation. This research paper explains the motivation for multibody parachute simulation, discusses implementation methods, and presents validation of this capability.

  8. An Aqueous Thermodynamic Model for the Complexation of Sodium and Strontium with Organic Chelators valid to High Ionic Strength. II. N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid (HEDTA)

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin J.; Qafoku, Odeta

    2003-04-01

    This is the second paper in a two part series on the development of aqueous thermodynamic models for the complexation of Na+ and Sr2+ with organic chelators. In this paper the development of an aqueous thermodynamic model describing the effects of ionic strength, carbonate concentration, and temperature on the complexation of Sr2+ by HEDTA under basic conditions is presented. The thermodynamic model describing the Na+ interactions with the HEDTA3- chelate relies solely on the use of Pitzer ion-interaction parameters. The exclusive use of Pitzer ion-interaction parameters differs significantly from our previous model for EDTA, which required the introduction of a NaEDTA3- ion pair. Estimation of the Pitzer ion-interaction parameters for HEDTA3- and SrHEDTA- with Na+ allows the extrapolation of a standard state equilibrium constant for the SrHEDTA- species which is one order of magnitude greater than the 0.1M reference state value available in the literature. The overall model is developed from data available in the literature on apparent equilibrium constants for HEDTA protonation, the solubility of salts in concentrated HEDTA solutions, and from new data on the solubility of SrCO3(c) obtained as part of this study. The predictions of the final thermodynamic model for the Na-Sr-OH-CO3-NO3-HEDTA-H2O system are tested by application to chemical systems containing competing metal ions (i.e., Ca2+).

  9. Factorial validity and measurement invariance across intelligence levels and gender of the overexcitabilities questionnaire-II (OEQ-II).

    PubMed

    Van den Broeck, Wim; Hofmans, Joeri; Cooremans, Sven; Staels, Eva

    2014-03-01

    The concept of overexcitability, derived from Dabrowski's theory of personality development, offers a promising approach for the study of the developmental dynamics of giftedness. The present study aimed at (a) examining the factorial structure of the Overexcitabilities Questionnaire-II scores (OEQ-II) and (b) testing measurement invariance of these scores across intelligence and gender. A sample of 641 Dutch-speaking adolescents from 11 to 15 years old, 363 girls and 278 boys, participated in this study. Results showed that a model without cross-loadings did not fit the data well (using confirmatory factor analysis), whereas a factor model in which all cross-loadings were included yielded fit statistics that were in support of the factorial structure of the OEQ-II scores (using exploratory structural equation modeling). Furthermore, our findings supported the assumption of (partial) strict measurement invariance of the OEQ-II scores across intelligence levels and across gender. Such levels of measurement invariance allow valid comparisons between factor means and factor relationships across groups. In particular, the gifted group scored significantly higher on intellectual and sensual overexcitability (OE) than the nongifted group, girls scored higher on emotional and sensual OE than boys, and boys scored higher on intellectual and psychomotor OE than girls. PMID:24079958

  10. Thermomechanical model of hydration swelling in smectitic clays: II three-scale inter-phase mass transfer: homogenization and computational validation

    NASA Astrophysics Data System (ADS)

    Murad, Márcio A.

    1999-06-01

    In Part I a two-scale thermomechanical theory of expansive compacted clays composed of adsorbed water and clay platelets was derived using a mixture-theoretic approach and the Coleman and Noll method of exploitation of the entropy inequality. This approach led to a two-scale model which describes the interaction between thermal and hydration effects between the adsorbed water and clay minerals. The purpose of this paper is twofold. Firstly, partial results toward a three-scale model are derived by homogenizing the two-scale model for the clay particles (clusters of clay platelets and adsorbed water) with the bulk water (water next to the swelling particles). The three-scale model is of dual porosity type wherein the clay particles act as sources/sinks of water to the macroscale bulk phase flow. One of the notable consequences of the homogenization procedure is the natural derivation of a generalized inter-phase mass transfer equation between adsorbed and bulk water. Further, variational principles and finite element approximations based on the Galerkin method are proposed to discretize the two-scale model. Numerical simulations of a bentonitic clay used for engineered barrier of nuclear waste repository are performed and numerical results are presented showing the influence of physico-chemical effects on the performance of the clay buffer.

  11. Physical properties of solar chromospheric plages. III - Models based on Ca II and Mg II observations

    NASA Technical Reports Server (NTRS)

    Kelch, W. L.; Linsky, J. L.

    1978-01-01

    Solar plages are modeled using observations of both the Ca II K and the Mg II h and k lines. A partial-redistribution approach is employed for calculating the line profiles on the basis of a grid of five model chromospheres. The computed integrated emission intensities for the five atmospheric models are compared with observations of six regions on the sun as well as with models of active-chromosphere stars. It is concluded that the basic plage model grid proposed by Shine and Linsky (1974) is still valid when the Mg II lines are included in the analysis and the Ca II and Mg II lines are analyzed using partial-redistribution diagnostics.

  12. Preparation of Power Distribution System for High Penetration of Renewable Energy Part I. Dynamic Voltage Restorer for Voltage Regulation Pat II. Distribution Circuit Modeling and Validation

    NASA Astrophysics Data System (ADS)

    Khoshkbar Sadigh, Arash

    by simulation and experimental tests under various conditions considering all possible cases such as different amounts of voltage sag depth (VSD), different amounts of point-on-wave (POW) at which voltage sag occurs, harmonic distortion, line frequency variation, and phase jump (PJ). Furthermore, the ripple amount of fundamental voltage amplitude calculated by the proposed method and its error is analyzed considering the line frequency variation together with harmonic distortion. The best and worst detection time of proposed method were measured 1ms and 8.8ms, respectively. Finally, the proposed method has been compared with other voltage sag detection methods available in literature. Part 2: Power System Modeling for Renewable Energy Integration: As power distribution systems are evolving into more complex networks, electrical engineers have to rely on software tools to perform circuit analysis. There are dozens of powerful software tools available in the market to perform the power system studies. Although their main functions are similar, there are differences in features and formatting structures to suit specific applications. This creates challenges for transferring power system circuit models data (PSCMD) between different software and rebuilding the same circuit in the second software environment. The objective of this part of thesis is to develop a Unified Platform (UP) to facilitate transferring PSCMD among different software packages and relieve the challenges of the circuit model conversion process. UP uses a commonly available spreadsheet file with a defined format, for any home software to write data to and for any destination software to read data from, via a script-based application called PSCMD transfer application. The main considerations in developing the UP are to minimize manual intervention and import a one-line diagram into the destination software or export it from the source software, with all details to allow load flow, short circuit and

  13. NASA GSFC CCMC Recent Model Validation Activities

    NASA Technical Reports Server (NTRS)

    Rastaetter, L.; Pulkkinen, A.; Taktakishvill, A.; Macneice, P.; Shim, J. S.; Zheng, Yihua; Kuznetsova, M. M.; Hesse, M.

    2012-01-01

    The Community Coordinated Modeling Center (CCMC) holds the largest assembly of state-of-the-art physics-based space weather models developed by the international space physics community. In addition to providing the community easy access to these modern space research models to support science research, its another primary goal is to test and validate models for transition from research to operations. In this presentation, we provide an overview of the space science models available at CCMC. Then we will focus on the community-wide model validation efforts led by CCMC in all domains of the Sun-Earth system and the internal validation efforts at CCMC to support space weather servicesjoperations provided its sibling organization - NASA GSFC Space Weather Center (http://swc.gsfc.nasa.gov). We will also discuss our efforts in operational model validation in collaboration with NOAA/SWPC.

  14. Algorithm for model validation: Theory and applications

    PubMed Central

    Sornette, D.; Davis, A. B.; Ide, K.; Vixie, K. R.; Pisarenko, V.; Kamm, J. R.

    2007-01-01

    Validation is often defined as the process of determining the degree to which a model is an accurate representation of the real world from the perspective of its intended uses. Validation is crucial as industries and governments depend increasingly on predictions by computer models to justify their decisions. We propose to formulate the validation of a given model as an iterative construction process that mimics the often implicit process occurring in the minds of scientists. We offer a formal representation of the progressive build-up of trust in the model. Thus, we replace static claims on the impossibility of validating a given model by a dynamic process of constructive approximation. This approach is better adapted to the fuzzy, coarse-grained nature of validation. Our procedure factors in the degree of redundancy versus novelty of the experiments used for validation as well as the degree to which the model predicts the observations. We illustrate the methodology first with the maturation of quantum mechanics as the arguably best established physics theory and then with several concrete examples drawn from some of our primary scientific interests: a cellular automaton model for earthquakes, a multifractal random walk model for financial time series, an anomalous diffusion model for solar radiation transport in the cloudy atmosphere, and a computational fluid dynamics code for the Richtmyer–Meshkov instability. PMID:17420476

  15. Algorithm for model validation: theory and applications.

    PubMed

    Sornette, D; Davis, A B; Ide, K; Vixie, K R; Pisarenko, V; Kamm, J R

    2007-04-17

    Validation is often defined as the process of determining the degree to which a model is an accurate representation of the real world from the perspective of its intended uses. Validation is crucial as industries and governments depend increasingly on predictions by computer models to justify their decisions. We propose to formulate the validation of a given model as an iterative construction process that mimics the often implicit process occurring in the minds of scientists. We offer a formal representation of the progressive build-up of trust in the model. Thus, we replace static claims on the impossibility of validating a given model by a dynamic process of constructive approximation. This approach is better adapted to the fuzzy, coarse-grained nature of validation. Our procedure factors in the degree of redundancy versus novelty of the experiments used for validation as well as the degree to which the model predicts the observations. We illustrate the methodology first with the maturation of quantum mechanics as the arguably best established physics theory and then with several concrete examples drawn from some of our primary scientific interests: a cellular automaton model for earthquakes, a multifractal random walk model for financial time series, an anomalous diffusion model for solar radiation transport in the cloudy atmosphere, and a computational fluid dynamics code for the Richtmyer-Meshkov instability. PMID:17420476

  16. A Validation Model for Administrative Competencies.

    ERIC Educational Resources Information Center

    Greer, John T.; Lockridge, Burma L.

    1974-01-01

    This paper presents a model for the identification and validation of competencies, designed as an all-inclusive framework, which may be adapted for specific situations. The criteria for including data in the validation process are as follows: (a) if the data are to be employed in making decisions about individuals or groups, all available evidence…

  17. Systematic Independent Validation of Inner Heliospheric Models

    NASA Technical Reports Server (NTRS)

    MacNeice, P. J.; Takakishvili, Alexandre

    2008-01-01

    This presentation is the first in a series which will provide independent validation of community models of the outer corona and inner heliosphere. In this work we establish a set of measures to be used in validating this group of models. We use these procedures to generate a comprehensive set of results from the Wang- Sheeley-Arge (WSA) model which will be used as a baseline, or reference, against which to compare all other models. We also run a test of the validation procedures by applying them to a small set of results produced by the ENLIL Magnetohydrodynamic (MHD) model. In future presentations we will validate other models currently hosted by the Community Coordinated Modeling Center(CCMC), including a comprehensive validation of the ENLIL model. The Wang-Sheeley-Arge (WSA) model is widely used to model the Solar wind, and is used by a number of agencies to predict Solar wind conditions at Earth as much as four days into the future. Because it is so important to both the research and space weather forecasting communities, it is essential that its performance be measured systematically, and independently. In this paper we offer just such an independent and systematic validation. We report skill scores for the model's predictions of wind speed and IMF polarity for a large set of Carrington rotations. The model was run in all its routinely used configurations. It ingests line of sight magnetograms. For this study we generated model results for monthly magnetograms from the National Solar Observatory (SOLIS), Mount Wilson Observatory and the GONG network, spanning the Carrington rotation range from 1650 to 2068. We compare the influence of the different magnetogram sources, performance at quiet and active times, and estimate the effect of different empirical wind speed tunings. We also consider the ability of the WSA model to identify sharp transitions in wind speed from slow to fast wind. These results will serve as a baseline against which to compare future

  18. Validation of a watershed model without calibration

    NASA Astrophysics Data System (ADS)

    Vogel, Richard M.; Sankarasubramanian, A.

    2003-10-01

    Traditional approaches for the validation of watershed models focus on the "goodness of fit" between model predictions and observations. It is possible for a watershed model to exhibit a "good" fit, yet not accurately represent hydrologic processes; hence "goodness of fit" can be misleading. Instead, we introduce an approach which evaluates the ability of a model to represent the observed covariance structure of the input (climate) and output (streamflow) without ever calibrating the model. An advantage of this approach is that it is not confounded by model error introduced during the calibration process. We illustrate that once a watershed model is calibrated, the unavoidable model error can cloud our ability to validate (or invalidate) the model. We emphasize that model hypothesis testing (validation) should be performed prior to, and independent of, parameter estimation (calibration), contrary to traditional practice in which watershed models are usually validated after calibrating the model. Our approach is tested using two different watershed models at a number of different watersheds in the United States.

  19. Validity of the Sleep Subscale of the Diagnostic Assessment for the Severely Handicapped-II (DASH-II)

    ERIC Educational Resources Information Center

    Matson, Johnny L.; Malone, Carrie J.

    2006-01-01

    Currently there are no available sleep disorder measures for individuals with severe and profound intellectual disability. We, therefore, attempted to establish the external validity of the "Diagnostic Assessment for the Severely Handicapped-II" (DASH-II) sleep subscale by comparing daily observational sleep data with the responses of direct care…

  20. Local thermal seeing modeling validation through observatory measurements

    NASA Astrophysics Data System (ADS)

    Vogiatzis, Konstantinos; Otarola, Angel; Skidmore, Warren; Travouillon, Tony; Angeli, George

    2012-09-01

    Dome and mirror seeing are critical effects influencing the optical performance of ground-based telescopes. Computational Fluid Dynamics (CFD) can be used to obtain the refractive index field along a given optical path and calculate the corresponding image quality utilizing optical modeling tools. This procedure is validated using measurements from the Keck II and CFHT telescopes. CFD models of Keck II and CFHT observatories on the Mauna Kea summit have been developed. The detailed models resolve all components that can influence the flow pattern through turbulence generation or heat release. Unsteady simulations generate time records of velocity and temperature fields from which the refractive index field at a given wavelength and turbulence parameters are obtained. At Keck II the Cn2 and l0 (inner scale of turbulence) were monitored along a 63m path sensitive primarily to turbulence around the top ring of the telescope tube. For validation, these parameters were derived from temperature and velocity fluctuations obtained from CFD simulations. At CFHT dome seeing has been inferred from their database that includes telescope delivered Image Quality (IQ). For this case CFD simulations were run for specific orientations of the telescope respect to incoming wind, wind speeds and outside air temperature. For validation, temperature fluctuations along the optical beam from the CFD are turned to refractive index variations and corresponding Optical Path Differences (OPD) then to Point Spread Functions (PSF) that are ultimately compared to the record of IQ.

  1. Empirical assessment of model validity

    SciTech Connect

    Wolfe, R.R. )

    1991-05-01

    The metabolism of amino acids is far more complicated than a 1- to 2-pool model. Yet, these simple models have been extensively used with many different isotopically labeled tracers to study protein metabolism. A tracer of leucine and measurement of leucine kinetics has been a favorite choice for following protein metabolism. However, administering a leucine tracer and following it in blood will not adequately reflect the complex multi-pool nature of the leucine system. Using the tracer enrichment of the ketoacid metabolite of leucine, alpha-ketoisocaproate (KIC), to reflect intracellular events of leucine was an important improvement. Whether this approach is adequate to follow accurately leucine metabolism in vivo or not has not been tested. From data obtained using simultaneous administration of leucine and KIC tracers, we developed a 10-pool model of the in vivo leucine-KIC and bicarbonate kinetic system. Data from this model were compared with conventional measurements of leucine kinetics. The results from the 10-pool model agreed best with the simplified approach using a leucine tracer and measurement of KIC enrichment.

  2. Validation of a Lagrangian particle model

    NASA Astrophysics Data System (ADS)

    Brzozowska, Lucyna

    2013-05-01

    In this paper a custom-developed model of dispersion of pollutants is presented. The proposed approach is based on both a Lagrangian particle model and an urban-scale diagnostic model of the air velocity field. Both models constitute a part of an operational air quality assessment system. The proposed model is validated by comparing its computed results with the results of measurements obtained in a wind tunnel reflecting conditions of the Mock Urban Setting Test (MUST) experiment. Commonly used measures of errors and model concordance are employed and the results obtained are additionally compared with those obtained by other authors for CFD and non-CFD class models. The obtained results indicate that the validity of the model presented in this paper is acceptable.

  3. Validation of the Hot Strip Mill Model

    SciTech Connect

    Richard Shulkosky; David Rosberg; Jerrud Chapman

    2005-03-30

    The Hot Strip Mill Model (HSMM) is an off-line, PC based software originally developed by the University of British Columbia (UBC) and the National Institute of Standards and Technology (NIST) under the AISI/DOE Advanced Process Control Program. The HSMM was developed to predict the temperatures, deformations, microstructure evolution and mechanical properties of steel strip or plate rolled in a hot mill. INTEG process group inc. undertook the current task of enhancing and validating the technology. With the support of 5 North American steel producers, INTEG process group tested and validated the model using actual operating data from the steel plants and enhanced the model to improve prediction results.

  4. On validation and invalidation of biological models

    PubMed Central

    Anderson, James; Papachristodoulou, Antonis

    2009-01-01

    Background Very frequently the same biological system is described by several, sometimes competing mathematical models. This usually creates confusion around their validity, ie, which one is correct. However, this is unnecessary since validity of a model cannot be established; model validation is actually a misnomer. In principle the only statement that one can make about a system model is that it is incorrect, ie, invalid, a fact which can be established given appropriate experimental data. Nonlinear models of high dimension and with many parameters are impossible to invalidate through simulation and as such the invalidation process is often overlooked or ignored. Results We develop different approaches for showing how competing ordinary differential equation (ODE) based models of the same biological phenomenon containing nonlinearities and parametric uncertainty can be invalidated using experimental data. We first emphasize the strong interplay between system identification and model invalidation and we describe a method for obtaining a lower bound on the error between candidate model predictions and data. We then turn to model invalidation and formulate a methodology for discrete-time and continuous-time model invalidation. The methodology is algorithmic and uses Semidefinite Programming as the computational tool. It is emphasized that trying to invalidate complex nonlinear models through exhaustive simulation is not only computationally intractable but also inconclusive. Conclusion Biological models derived from experimental data can never be validated. In fact, in order to understand biological function one should try to invalidate models that are incompatible with available data. This work describes a framework for invalidating both continuous and discrete-time ODE models based on convex optimization techniques. The methodology does not require any simulation of the candidate models; the algorithms presented in this paper have a worst case polynomial time

  5. HYDRA-II: A hydrothermal analysis computer code: Volume 3, Verification/validation assessments

    SciTech Connect

    McCann, R.A.; Lowery, P.S.

    1987-10-01

    HYDRA-II is a hydrothermal computer code capable of three-dimensional analysis of coupled conduction, convection, and thermal radiation problems. This code is especially appropriate for simulating the steady-state performance of spent fuel storage systems. The code has been evaluated for this application for the US Department of Energy's Commercial Spent Fuel Management Program. HYDRA-II provides a finite difference solution in cartesian coordinates to the equations governing the conservation of mass, momentum, and energy. A cylindrical coordinate system may also be used to enclose the cartesian coordinate system. This exterior coordinate system is useful for modeling cylindrical cask bodies. The difference equations for conservation of momentum are enhanced by the incorporation of directional porosities and permeabilities that aid in modeling solid structures whose dimensions may be smaller than the computational mesh. The equation for conservation of energy permits modeling of orthotropic physical properties and film resistances. Several automated procedures are available to model radiation transfer within enclosures and from fuel rod to fuel rod. The documentation of HYDRA-II is presented in three separate volumes. Volume I - Equations and Numerics describes the basic differential equations, illustrates how the difference equations are formulated, and gives the solution procedures employed. Volume II - User's Manual contains code flow charts, discusses the code structure, provides detailed instructions for preparing an input file, and illustrates the operation of the code by means of a model problem. This volume, Volume III - Verification/Validation Assessments, provides a comparison between the analytical solution and the numerical simulation for problems with a known solution. This volume also documents comparisons between the results of simulations of single- and multiassembly storage systems and actual experimental data. 11 refs., 55 figs., 13 tabs.

  6. Structural system identification: Structural dynamics model validation

    SciTech Connect

    Red-Horse, J.R.

    1997-04-01

    Structural system identification is concerned with the development of systematic procedures and tools for developing predictive analytical models based on a physical structure`s dynamic response characteristics. It is a multidisciplinary process that involves the ability (1) to define high fidelity physics-based analysis models, (2) to acquire accurate test-derived information for physical specimens using diagnostic experiments, (3) to validate the numerical simulation model by reconciling differences that inevitably exist between the analysis model and the experimental data, and (4) to quantify uncertainties in the final system models and subsequent numerical simulations. The goal of this project was to develop structural system identification techniques and software suitable for both research and production applications in code and model validation.

  7. Oil spill impact modeling: development and validation.

    PubMed

    French-McCay, Deborah P

    2004-10-01

    A coupled oil fate and effects model has been developed for the estimation of impacts to habitats, wildlife, and aquatic organisms resulting from acute exposure to spilled oil. The physical fates model estimates the distribution of oil (as mass and concentrations) on the water surface, on shorelines, in the water column, and in the sediments, accounting for spreading, evaporation, transport, dispersion, emulsification, entrainment, dissolution, volatilization, partitioning, sedimentation, and degradation. The biological effects model estimates exposure of biota of various behavior types to floating oil and subsurface contamination, resulting percent mortality, and sublethal effects on production (somatic growth). Impacts are summarized as areas or volumes affected, percent of populations lost, and production foregone because of a spill's effects. This paper summarizes existing information and data used to develop the model, model algorithms and assumptions, validation studies, and research needs. Simulation of the Exxon Valdez oil spill is presented as a case study and validation of the model. PMID:15511105

  8. Feature extraction for structural dynamics model validation

    SciTech Connect

    Hemez, Francois; Farrar, Charles; Park, Gyuhae; Nishio, Mayuko; Worden, Keith; Takeda, Nobuo

    2010-11-08

    This study focuses on defining and comparing response features that can be used for structural dynamics model validation studies. Features extracted from dynamic responses obtained analytically or experimentally, such as basic signal statistics, frequency spectra, and estimated time-series models, can be used to compare characteristics of structural system dynamics. By comparing those response features extracted from experimental data and numerical outputs, validation and uncertainty quantification of numerical model containing uncertain parameters can be realized. In this study, the applicability of some response features to model validation is first discussed using measured data from a simple test-bed structure and the associated numerical simulations of these experiments. issues that must be considered were sensitivity, dimensionality, type of response, and presence or absence of measurement noise in the response. Furthermore, we illustrate a comparison method of multivariate feature vectors for statistical model validation. Results show that the outlier detection technique using the Mahalanobis distance metric can be used as an effective and quantifiable technique for selecting appropriate model parameters. However, in this process, one must not only consider the sensitivity of the features being used, but also correlation of the parameters being compared.

  9. Validation of an Experimentally Derived Uncertainty Model

    NASA Technical Reports Server (NTRS)

    Lim, K. B.; Cox, D. E.; Balas, G. J.; Juang, J.-N.

    1996-01-01

    The results show that uncertainty models can be obtained directly from system identification data by using a minimum norm model validation approach. The error between the test data and an analytical nominal model is modeled as a combination of unstructured additive and structured input multiplicative uncertainty. Robust controllers which use the experimentally derived uncertainty model show significant stability and performance improvements over controllers designed with assumed ad hoc uncertainty levels. Use of the identified uncertainty model also allowed a strong correlation between design predictions and experimental results.

  10. Evaluation (not validation) of quantitative models.

    PubMed

    Oreskes, N

    1998-12-01

    The present regulatory climate has led to increasing demands for scientists to attest to the predictive reliability of numerical simulation models used to help set public policy, a process frequently referred to as model validation. But while model validation may reveal useful information, this paper argues that it is not possible to demonstrate the predictive reliability of any model of a complex natural system in advance of its actual use. All models embed uncertainties, and these uncertainties can and frequently do undermine predictive reliability. In the case of lead in the environment, we may categorize model uncertainties as theoretical, empirical, parametrical, and temporal. Theoretical uncertainties are aspects of the system that are not fully understood, such as the biokinetic pathways of lead metabolism. Empirical uncertainties are aspects of the system that are difficult (or impossible) to measure, such as actual lead ingestion by an individual child. Parametrical uncertainties arise when complexities in the system are simplified to provide manageable model input, such as representing longitudinal lead exposure by cross-sectional measurements. Temporal uncertainties arise from the assumption that systems are stable in time. A model may also be conceptually flawed. The Ptolemaic system of astronomy is a historical example of a model that was empirically adequate but based on a wrong conceptualization. Yet had it been computerized--and had the word then existed--its users would have had every right to call it validated. Thus, rather than talking about strategies for validation, we should be talking about means of evaluation. That is not to say that language alone will solve our problems or that the problems of model evaluation are primarily linguistic. The uncertainties inherent in large, complex models will not go away simply because we change the way we talk about them. But this is precisely the point: calling a model validated does not make it valid

  11. Evaluation (not validation) of quantitative models.

    PubMed Central

    Oreskes, N

    1998-01-01

    The present regulatory climate has led to increasing demands for scientists to attest to the predictive reliability of numerical simulation models used to help set public policy, a process frequently referred to as model validation. But while model validation may reveal useful information, this paper argues that it is not possible to demonstrate the predictive reliability of any model of a complex natural system in advance of its actual use. All models embed uncertainties, and these uncertainties can and frequently do undermine predictive reliability. In the case of lead in the environment, we may categorize model uncertainties as theoretical, empirical, parametrical, and temporal. Theoretical uncertainties are aspects of the system that are not fully understood, such as the biokinetic pathways of lead metabolism. Empirical uncertainties are aspects of the system that are difficult (or impossible) to measure, such as actual lead ingestion by an individual child. Parametrical uncertainties arise when complexities in the system are simplified to provide manageable model input, such as representing longitudinal lead exposure by cross-sectional measurements. Temporal uncertainties arise from the assumption that systems are stable in time. A model may also be conceptually flawed. The Ptolemaic system of astronomy is a historical example of a model that was empirically adequate but based on a wrong conceptualization. Yet had it been computerized--and had the word then existed--its users would have had every right to call it validated. Thus, rather than talking about strategies for validation, we should be talking about means of evaluation. That is not to say that language alone will solve our problems or that the problems of model evaluation are primarily linguistic. The uncertainties inherent in large, complex models will not go away simply because we change the way we talk about them. But this is precisely the point: calling a model validated does not make it valid

  12. Validation of Space Weather Models at Community Coordinated Modeling Center

    NASA Technical Reports Server (NTRS)

    Kuznetsova, M. M.; Pulkkinen, A.; Rastaetter, L.; Hesse, M.; Chulaki, A.; Maddox, M.

    2011-01-01

    The Community Coordinated Modeling Center (CCMC) is a multiagency partnership, which aims at the creation of next generation space weather modes. CCMC goal is to support the research and developmental work necessary to substantially increase space weather modeling capabilities and to facilitate advanced models deployment in forecasting operations. The CCMC conducts unbiased model testing and validation and evaluates model readiness for operational environment. The presentation will demonstrate the recent progress in CCMC metrics and validation activities.

  13. Validation of chemometric models - a tutorial.

    PubMed

    Westad, Frank; Marini, Federico

    2015-09-17

    In this tutorial, we focus on validation both from a numerical and conceptual point of view. The often applied reported procedure in the literature of (repeatedly) dividing a dataset randomly into a calibration and test set must be applied with care. It can only be justified when there is no systematic stratification of the objects that will affect the validated estimates or figures of merits such as RMSE or R(2). The various levels of validation may, typically, be repeatability, reproducibility, and instrument and raw material variation. Examples of how one data set can be validated across this background information illustrate that it will affect the figures of merits as well as the dimensionality of the models. Even more important is the robustness of the models for predicting future samples. Another aspect that is brought to attention is validation in terms of the overall conclusions when observing a specific system. One example is to apply several methods for finding the significant variables and see if there is a consensus subset that also matches what is reported in the literature or based on the underlying chemistry. PMID:26398418

  14. Real-time remote scientific model validation

    NASA Technical Reports Server (NTRS)

    Frainier, Richard; Groleau, Nicolas

    1994-01-01

    This paper describes flight results from the use of a CLIPS-based validation facility to compare analyzed data from a space life sciences (SLS) experiment to an investigator's preflight model. The comparison, performed in real-time, either confirms or refutes the model and its predictions. This result then becomes the basis for continuing or modifying the investigator's experiment protocol. Typically, neither the astronaut crew in Spacelab nor the ground-based investigator team are able to react to their experiment data in real time. This facility, part of a larger science advisor system called Principal Investigator in a Box, was flown on the space shuttle in October, 1993. The software system aided the conduct of a human vestibular physiology experiment and was able to outperform humans in the tasks of data integrity assurance, data analysis, and scientific model validation. Of twelve preflight hypotheses associated with investigator's model, seven were confirmed and five were rejected or compromised.

  15. A Hierarchical Systems Approach to Model Validation

    NASA Astrophysics Data System (ADS)

    Easterbrook, S. M.

    2011-12-01

    Existing approaches to the question of how climate models should be evaluated tend to rely on either philosophical arguments about the status of models as scientific tools, or on empirical arguments about how well runs from a given model match observational data. These have led to quantitative approaches expressed in terms of model bias or forecast skill, and ensemble approaches where models are assessed according to the extent to which the ensemble brackets the observational data. Unfortunately, such approaches focus the evaluation on models per se (or more specifically, on the simulation runs they produce) as though the models can be isolated from their context. Such approach may overlook a number of important aspects of the use of climate models: - the process by which models are selected and configured for a given scientific question. - the process by which model outputs are selected, aggregated and interpreted by a community of expertise in climatology. - the software fidelity of the models (i.e. whether the running code is actually doing what the modellers think it's doing). - the (often convoluted) history that begat a given model, along with the modelling choices long embedded in the code. - variability in the scientific maturity of different model components within a coupled system. These omissions mean that quantitative approaches cannot assess whether a model produces the right results for the wrong reasons, or conversely, the wrong results for the right reasons (where, say the observational data is problematic, or the model is configured to be unlike the earth system for a specific reason). Hence, we argue that it is a mistake to think that validation is a post-hoc process to be applied to an individual "finished" model, to ensure it meets some criteria for fidelity to the real world. We are therefore developing a framework for model validation that extends current approaches down into the detailed codebase and the processes by which the code is built

  16. Calibration and validation of rockfall models

    NASA Astrophysics Data System (ADS)

    Frattini, Paolo; Valagussa, Andrea; Zenoni, Stefania; Crosta, Giovanni B.

    2013-04-01

    Calibrating and validating landslide models is extremely difficult due to the particular characteristic of landslides: limited recurrence in time, relatively low frequency of the events, short durability of post-event traces, poor availability of continuous monitoring data, especially for small landslide and rockfalls. For this reason, most of the rockfall models presented in literature completely lack calibration and validation of the results. In this contribution, we explore different strategies for rockfall model calibration and validation starting from both an historical event and a full-scale field test. The event occurred in 2012 in Courmayeur (Western Alps, Italy), and caused serious damages to quarrying facilities. This event has been studied soon after the occurrence through a field campaign aimed at mapping the blocks arrested along the slope, the shape and location of the detachment area, and the traces of scars associated to impacts of blocks on the slope. The full-scale field test was performed by Geovert Ltd in the Christchurch area (New Zealand) after the 2011 earthquake. During the test, a number of large blocks have been mobilized from the upper part of the slope and filmed with high velocity cameras from different viewpoints. The movies of each released block were analysed to identify the block shape, the propagation path, the location of impacts, the height of the trajectory and the velocity of the block along the path. Both calibration and validation of rockfall models should be based on the optimization of the agreement between the actual trajectories or location of arrested blocks and the simulated ones. A measure that describe this agreement is therefore needed. For calibration purpose, this measure should simple enough to allow trial and error repetitions of the model for parameter optimization. In this contribution we explore different calibration/validation measures: (1) the percentage of simulated blocks arresting within a buffer of the

  17. Solar Sail Model Validation from Echo Trajectories

    NASA Technical Reports Server (NTRS)

    Heaton, Andrew F.; Brickerhoff, Adam T.

    2007-01-01

    The NASA In-Space Propulsion program has been engaged in a project to increase the technology readiness of solar sails. Recently, these efforts came to fruition in the form of several software tools to model solar sail guidance, navigation and control. Furthermore, solar sails are one of five technologies competing for the New Millennium Program Space Technology 9 flight demonstration mission. The historic Echo 1 and Echo 2 balloons were comprised of aluminized Mylar, which is the near-term material of choice for solar sails. Both spacecraft, but particularly Echo 2, were in low Earth orbits with characteristics similar to the proposed Space Technology 9 orbit. Therefore, the Echo balloons are excellent test cases for solar sail model validation. We present the results of studies of Echo trajectories that validate solar sail models of optics, solar radiation pressure, shape and low-thrust orbital dynamics.

  18. Pain Documentation: Validation of a Reference Model.

    PubMed

    Gesner, Emily; Collins, Sarah A; Rocha, Roberto

    2015-01-01

    Over the last decade, interoperability of the Electronic Health Record (EHR) is becoming more of a reality. However, inconsistencies in documentation such as pain are considered a barrier to obtaining this goal. In order to be able to remedy this issue, it is necessary to validate reference models that have been created based upon requirements defined by Health Level 7 (HL7), Logical Names and Codes (LOINC) and the Intermountain Clinical Element Model using external published sources and guidelines. Using pain as an example of complex and inconsistent documentation, it was found that the reference model based upon these standards is valid because the data elements identified are broad and can meet the needs of each sub-domain within the primary domain of pain. PMID:26262163

  19. Predicting Backdrafting and Spillage for Natural-Draft Gas Combustion Appliances: Validating VENT-II

    SciTech Connect

    Rapp, Vi H.; Pastor-Perez, Albert; Singer, Brett C.; Wray, Craig P.

    2013-04-01

    VENT-II is a computer program designed to provide detailed analysis of natural draft and induced draft combustion appliance vent-systems (i.e., furnace or water heater). This program is capable of predicting house depressurization thresholds that lead to backdrafting and spillage of combustion appliances; however, validation reports of the program being applied for this purpose are not readily available. The purpose of this report is to assess VENT-II’s ability to predict combustion gas spillage events due to house depressurization by comparing VENT-II simulated results with experimental data for four appliance configurations. The results show that VENT-II correctly predicts depressurizations resulting in spillage for natural draft appliances operating in cold and mild outdoor conditions, but not for hot conditions. In the latter case, the predicted depressurizations depend on whether the vent section is defined as part of the vent connector or the common vent when setting up the model. Overall, the VENTII solver requires further investigation before it can be used reliably to predict spillage caused by depressurization over a full year of weather conditions, especially where hot conditions occur.

  20. Using Model Checking to Validate AI Planner Domain Models

    NASA Technical Reports Server (NTRS)

    Penix, John; Pecheur, Charles; Havelund, Klaus

    1999-01-01

    This report describes an investigation into using model checking to assist validation of domain models for the HSTS planner. The planner models are specified using a qualitative temporal interval logic with quantitative duration constraints. We conducted several experiments to translate the domain modeling language into the SMV, Spin and Murphi model checkers. This allowed a direct comparison of how the different systems would support specific types of validation tasks. The preliminary results indicate that model checking is useful for finding faults in models that may not be easily identified by generating test plans.

  1. Paleoclimate validation of a numerical climate model

    SciTech Connect

    Schelling, F.J.; Church, H.W.; Zak, B.D.; Thompson, S.L.

    1994-04-01

    An analysis planned to validate regional climate model results for a past climate state at Yucca Mountain, Nevada, against paleoclimate evidence for the period is described. This analysis, which will use the GENESIS model of global climate nested with the RegCM2 regional climate model, is part of a larger study for DOE`s Yucca Mountain Site Characterization Project that is evaluating the impacts of long term future climate change on performance of the potential high level nuclear waste repository at Yucca Mountain. The planned analysis and anticipated results are presented.

  2. Beyond the Standard Model II

    NASA Astrophysics Data System (ADS)

    Milton, Kimball A.; Kantowski, Ronald; Samuel, Mark A.

    1991-07-01

    Future Prospects * Quantum Mechanics at the Black Hole Horizon * Target-Space Duality and the Curse of the Wormhole * Mass Enhancement and Critical Behavior in Technicolor Theories * Proton-Proton and Proton-Antiproton Elastic Scattering at High Energies - Theory, Phenomenology, and Experiment * Gauge Masses in String Field Theory * An Introduction to Bosonic Technicolor * Anyonic Superconductivity * Hunting the Higgs Boson at LEP with OPAL * Beyond the Standard Model - The Sextet Quarks Way * Dynamical Breakdown of Z2 and Parity in QED3 with Fermion Self-Coupling * Scaling Properties of QED3 with Fermion Self-Couplings * Wheeler-DeWitt Quantum Gravity in (2+1) Dimensions * Kac-Moody Algebras from Covariantization of the Lax Operators * An Upper Bound on the Higgs Mass * Suppression of the Vacuum Energy Expectation Value * Lorentz Covariance of Quantum Fluctuations in Quantum Field Theory * The Gauge Invariance of the Critical Curve in Strong-coupling Gauge Theory * Heavy W Decays into Sfermions and a Photon * New Insights on Majoron Models * Program of Beyond the Standard Model II * List of Participants

  3. Using airborne laser scanning profiles to validate marine geoid models

    NASA Astrophysics Data System (ADS)

    Julge, Kalev; Gruno, Anti; Ellmann, Artu; Liibusk, Aive; Oja, Tõnis

    2014-05-01

    Airborne laser scanning (ALS) is a remote sensing method which utilizes LiDAR (Light Detection And Ranging) technology. The datasets collected are important sources for large range of scientific and engineering applications. Mostly the ALS is used to measure terrain surfaces for compilation of Digital Elevation Models but it can also be used in other applications. This contribution focuses on usage of ALS system for measuring sea surface heights and validating gravimetric geoid models over marine areas. This is based on the ALS ability to register echoes of LiDAR pulse from the water surface. A case study was carried out to analyse the possibilities for validating marine geoid models by using ALS profiles. A test area at the southern shores of the Gulf of Finland was selected for regional geoid validation. ALS measurements were carried out by the Estonian Land Board in spring 2013 at different altitudes and using different scan rates. The one wavelength Leica ALS50-II laser scanner on board of a small aircraft was used to determine the sea level (with respect to the GRS80 reference ellipsoid), which follows roughly the equipotential surface of the Earth's gravity field. For the validation a high-resolution (1'x2') regional gravimetric GRAV-GEOID2011 model was used. This geoid model covers the entire area of Estonia and surrounding waters of the Baltic Sea. The fit between the geoid model and GNSS/levelling data within the Estonian dry land revealed RMS of residuals ±1… ±2 cm. Note that such fitting validation cannot proceed over marine areas. Therefore, an ALS observation-based methodology was developed to evaluate the GRAV-GEOID2011 quality over marine areas. The accuracy of acquired ALS dataset were analyzed, also an optimal width of nadir-corridor containing good quality ALS data was determined. Impact of ALS scan angle range and flight altitude to obtainable vertical accuracy were investigated as well. The quality of point cloud is analysed by cross

  4. SPR Hydrostatic Column Model Verification and Validation.

    SciTech Connect

    Bettin, Giorgia; Lord, David; Rudeen, David Keith

    2015-10-01

    A Hydrostatic Column Model (HCM) was developed to help differentiate between normal "tight" well behavior and small-leak behavior under nitrogen for testing the pressure integrity of crude oil storage wells at the U.S. Strategic Petroleum Reserve. This effort was motivated by steady, yet distinct, pressure behavior of a series of Big Hill caverns that have been placed under nitrogen for extended period of time. This report describes the HCM model, its functional requirements, the model structure and the verification and validation process. Different modes of operation are also described, which illustrate how the software can be used to model extended nitrogen monitoring and Mechanical Integrity Tests by predicting wellhead pressures along with nitrogen interface movements. Model verification has shown that the program runs correctly and it is implemented as intended. The cavern BH101 long term nitrogen test was used to validate the model which showed very good agreement with measured data. This supports the claim that the model is, in fact, capturing the relevant physical phenomena and can be used to make accurate predictions of both wellhead pressure and interface movements.

  5. Thermodynamically valid noise models for nonlinear devices

    NASA Astrophysics Data System (ADS)

    Coram, Geoffrey J.

    2000-11-01

    Noise has been a concern from the very beginning of signal processing and electrical engineering in general, although it was perhaps of less interest until vacuum- tube amplifiers made it audible just after 1900. Rigorous noise models for linear resistors were developed in 1927 by Nyquist and Johnson [1, 2]. However, the intervening years have not brought similarly well-established models for noise in nonlinear devices. This thesis proposes using thermodynamic principles to determine whether a given nonlinear device noise model is physically valid. These tests are applied to several models. One conclusion is that the standard Gaussian noise models for nonlinear devices predict thermodynamically impossible circuit behavior: these models should be abandoned. But the nonlinear shot-noise model predicts thermodynamically acceptable behavior under a constraint derived here. This thesis shows how the thermodynamic requirements can be reduced to concise mathematical tests, involving no approximations, for the Gaussian and shot-noise models. When the above-mentioned constraint is satisfied, the nonlinear shot-noise model specifies the current noise amplitude at each operating point from knowledge of the device v - i curve alone. This relation between the dissipative behavior and the noise fluctuations is called, naturally enough, a fluctuation- dissipation relation. This thesis further investigates such FDRs, including one for linear resistors in nonlinear circuits that was previously unexplored. The aim of this thesis is to provide thermodynamically solid foundations for noise models. It is hoped that hypothesized noise models developed to match experiment will be validated against the concise mathematical tests of this thesis. Finding a correct noise model will help circuit designers and physicists understand the actual processes causing the noise, and perhaps help them minimize the noise or its effect in the circuit. (Copies available exclusively from MIT Libraries, Rm

  6. Hierarchical Model Validation of Symbolic Performance Models of Scientific Kernels

    SciTech Connect

    Alam, Sadaf R; Vetter, Jeffrey S

    2006-08-01

    Multi-resolution validation of hierarchical performance models of scientific applications is critical primarily for two reasons. First, the step-by-step validation determines the correctness of all essential components or phases in a science simulation. Second, a model that is validated at multiple resolution levels is the very first step to generate predictive performance models, for not only existing systems but also for emerging systems and future problem sizes. We present the design and validation of hierarchical performance models of two scientific benchmarks using a new technique called the modeling assertions (MA). Our MA prototype framework generates symbolic performance models that can be evaluated efficiently by generating the equivalent model representations in Octave and MATLAB. The multi-resolution modeling and validation is conducted on two contemporary, massively-parallel systems, XT3 and Blue Gene/L system. The workload distribution and the growth rates predictions generated by the MA models are confirmed by the experimental data collected on the MPP platforms. In addition, the physical memory requirements that are generated by the MA models are verified by the runtime values on the Blue Gene/L system, which has 512 MBytes and 256 MBytes physical memory capacity in its two unique execution modes.

  7. Predictive Validation of an Influenza Spread Model

    PubMed Central

    Hyder, Ayaz; Buckeridge, David L.; Leung, Brian

    2013-01-01

    Background Modeling plays a critical role in mitigating impacts of seasonal influenza epidemics. Complex simulation models are currently at the forefront of evaluating optimal mitigation strategies at multiple scales and levels of organization. Given their evaluative role, these models remain limited in their ability to predict and forecast future epidemics leading some researchers and public-health practitioners to question their usefulness. The objective of this study is to evaluate the predictive ability of an existing complex simulation model of influenza spread. Methods and Findings We used extensive data on past epidemics to demonstrate the process of predictive validation. This involved generalizing an individual-based model for influenza spread and fitting it to laboratory-confirmed influenza infection data from a single observed epidemic (1998–1999). Next, we used the fitted model and modified two of its parameters based on data on real-world perturbations (vaccination coverage by age group and strain type). Simulating epidemics under these changes allowed us to estimate the deviation/error between the expected epidemic curve under perturbation and observed epidemics taking place from 1999 to 2006. Our model was able to forecast absolute intensity and epidemic peak week several weeks earlier with reasonable reliability and depended on the method of forecasting-static or dynamic. Conclusions Good predictive ability of influenza epidemics is critical for implementing mitigation strategies in an effective and timely manner. Through the process of predictive validation applied to a current complex simulation model of influenza spread, we provided users of the model (e.g. public-health officials and policy-makers) with quantitative metrics and practical recommendations on mitigating impacts of seasonal influenza epidemics. This methodology may be applied to other models of communicable infectious diseases to test and potentially improve their predictive

  8. ExodusII Finite Element Data Model

    Energy Science and Technology Software Center (ESTSC)

    2005-05-14

    EXODUS II is a model developed to store and retrieve data for finite element analyses. It is used for preprocessing (problem definition), postprocessing (results visualization), as well as code to code data transfer. An EXODUS II data file is a random access, machine independent, binary file that is written and read via C, C++, or Fortran library routines which comprise the Application Programming Interface. (exodus II is based on netcdf)

  9. A decision support system (GesCoN) for managing fertigation in vegetable crops. Part II-model calibration and validation under different environmental growing conditions on field grown tomato.

    PubMed

    Conversa, Giulia; Bonasia, Anna; Di Gioia, Francesco; Elia, Antonio

    2015-01-01

    The GesCoN model was evaluated for its capability to simulate growth, nitrogen uptake, and productivity of open field tomato grown under different environmental and cultural conditions. Five datasets collected from experimental trials carried out in Foggia (IT) were used for calibration and 13 datasets collected from trials conducted in Foggia, Perugia (IT), and Florida (USA) were used for validation. The goodness of fitting was performed by comparing the observed and simulated shoot dry weight (SDW) and N crop uptake during crop seasons, total dry weight (TDW), N uptake and fresh yield (TFY). In SDW model calibration, the relative RMSE values fell within the good 10-15% range, percent BIAS (PBIAS) ranged between -11.5 and 7.4%. The Nash-Sutcliffe efficiency (NSE) was very close to the optimal value 1. In the N uptake calibration RRMSE and PBIAS were very low (7%, and -1.78, respectively) and NSE close to 1. The validation of SDW (RRMSE = 16.7%; NSE = 0.96) and N uptake (RRMSE = 16.8%; NSE = 0.96) showed the good accuracy of GesCoN. A model under- or overestimation of the SDW and N uptake occurred when higher or a lower N rates and/or a more or less efficient system were used compared to the calibration trial. The in-season adjustment, using the "SDWcheck" procedure, greatly improved model simulations both in the calibration and in the validation phases. The TFY prediction was quite good except in Florida, where a large overestimation (+16%) was linked to a different harvest index (0.53) compared to the cultivars used for model calibration and validation in Italian areas. The soil water content at the 10-30 cm depth appears to be well-simulated by the software, and the GesCoN proved to be able to adaptively control potential yield and DW accumulation under limited N soil availability scenarios and consequently to modify fertilizer application. The DSSwell simulate SDW accumulation and N uptake of different tomato genotypes grown under Mediterranean and subtropical

  10. Validation of Space Weather Models at Community Coordinated Modeling Center

    NASA Technical Reports Server (NTRS)

    Kuznetsova, M. M.; Hesse, M.; Pulkkinen, A.; Maddox, M.; Rastaetter, L.; Berrios, D.; Zheng, Y.; MacNeice, P. J.; Shim, J.; Taktakishvili, A.; Chulaki, A.

    2011-01-01

    The Community Coordinated Modeling Center (CCMC) is a multi-agency partnership to support the research and developmental work necessary to substantially increase space weather modeling capabilities and to facilitate advanced models deployment in forecasting operations. Space weather models and coupled model chains hosted at the CCMC range from the solar corona to the Earth's upper atmosphere. CCMC has developed a number of real-time modeling systems, as well as a large number of modeling and data products tailored to address the space weather needs of NASA's robotic missions. The CCMC conducts unbiased model testing and validation and evaluates model readiness for operational environment. CCMC has been leading recent comprehensive modeling challenges under GEM, CEDAR and SHINE programs. The presentation will focus on experience in carrying out comprehensive and systematic validation of large sets of. space weather models

  11. Turbulence Modeling Validation, Testing, and Development

    NASA Technical Reports Server (NTRS)

    Bardina, J. E.; Huang, P. G.; Coakley, T. J.

    1997-01-01

    The primary objective of this work is to provide accurate numerical solutions for selected flow fields and to compare and evaluate the performance of selected turbulence models with experimental results. Four popular turbulence models have been tested and validated against experimental data often turbulent flows. The models are: (1) the two-equation k-epsilon model of Wilcox, (2) the two-equation k-epsilon model of Launder and Sharma, (3) the two-equation k-omega/k-epsilon SST model of Menter, and (4) the one-equation model of Spalart and Allmaras. The flows investigated are five free shear flows consisting of a mixing layer, a round jet, a plane jet, a plane wake, and a compressible mixing layer; and five boundary layer flows consisting of an incompressible flat plate, a Mach 5 adiabatic flat plate, a separated boundary layer, an axisymmetric shock-wave/boundary layer interaction, and an RAE 2822 transonic airfoil. The experimental data for these flows are well established and have been extensively used in model developments. The results are shown in the following four sections: Part A describes the equations of motion and boundary conditions; Part B describes the model equations, constants, parameters, boundary conditions, and numerical implementation; and Parts C and D describe the experimental data and the performance of the models in the free-shear flows and the boundary layer flows, respectively.

  12. Validation of the Korean version Moorehead-Ardelt quality of life questionnaire II

    PubMed Central

    Lee, Yeon Ji; Song, Hyun Jin; Oh, Sung-Hee; Kwon, Jin Won; Moon, Kon-Hak; Park, Joong-Min; Lee, Sang Kuon

    2014-01-01

    Purpose To investigate the weight loss effects with higher sensitivity, disease specific quality of life (QoL) instruments were important. The Moorehead-Ardelt quality of life questionnaire II (MA-II) is widely used, because it was simple and validated the several languages. The aims of present study was performed the translation of MA-II Korean version and the validation compared with EuroQol-5 dimension (EQ-5D), obesity-related problems scale (OP-scale), and impact of weight quality of life-lite (IWQoL-Lite). Methods The study design was a multicenter, cross-sectional survey and this study was included the postoperative patients. The validation procedure is translation-back translation procedure, pilot study, and field study. The instruments of measuring QoL included the MA-II, EQ-5D, OP-scale, and IWQoL-lite. The reliability was checked through internal consistency using Cronbach alpha coefficients. The construct validity was assessed the Spearman rank correlation between 6 domains of MA-II and EQ-5D, OP-scale, and 5 domains of IWQoL-Lite. Results The Cronbach alpha of MA-II was 0.763, so the internal consistency was confirmed. The total score of MA-II was significantly correlated with all other instruments; EQ-5D, OP-scale, and IWQoL-Lite. IWQoL-lite (ρ = 0.623, P < 0.001) was showed the strongest correlation compared with MA-II, followed by OP-scale (ρ = 0.588, P < 0.001) and EQ-5D (ρ = 0.378, P < 0.01). Conclusion The Korean version MA-II was valid instrument of measuring the obesity-specific QoL. Through the present study, the MA-II was confirmed to have good reliability and validity and it was also answered simple for investigating. Thus, MA-II could be estimated sensitive and exact QoL in obesity patients. PMID:25368853

  13. Validation of Computational Models in Biomechanics

    PubMed Central

    Henninger, Heath B.; Reese, Shawn P.; Anderson, Andrew E.; Weiss, Jeffrey A.

    2010-01-01

    The topics of verification and validation (V&V) have increasingly been discussed in the field of computational biomechanics, and many recent articles have applied these concepts in an attempt to build credibility for models of complex biological systems. V&V are evolving techniques that, if used improperly, can lead to false conclusions about a system under study. In basic science these erroneous conclusions may lead to failure of a subsequent hypothesis, but they can have more profound effects if the model is designed to predict patient outcomes. While several authors have reviewed V&V as they pertain to traditional solid and fluid mechanics, it is the intent of this manuscript to present them in the context of computational biomechanics. Specifically, the task of model validation will be discussed with a focus on current techniques. It is hoped that this review will encourage investigators to engage and adopt the V&V process in an effort to increase peer acceptance of computational biomechanics models. PMID:20839648

  14. Session on validation of coupled models

    NASA Technical Reports Server (NTRS)

    Kuo, Bill

    1993-01-01

    The session on validation of coupled models is reviewed. The current use of a mesoscale model with a grid size of 20-km during STORM-FEST in 1992 has proven to be extremely valuable. The availability of forecast products at a much higher temporal and spatial resolution was very helpful for mesoscale forecasting, mission planning, and the guidance of research aircraft. Recent numerical simulation of ocean cyclones and mesoscsle convective systems using nonhydrostatic cloud/mesoscale models with a grid size as small as 2-km have demonstrated the potential of these models for predicting mesoscale convective systems, squall lines, hurricane rainbands, mesoscale gravity waves, and mesoscale frontal structures embedded within an extratropical cyclone. Although mesoscale/cloud scale models have demonstrated strong potential for use in operational forecasting, very limited quantitative evaluation (and verification) of these models were performed. As a result, the accuracy, the systematic biases, and the useful forecasts limits were not properly defined for these models. Also, no serious attempts were made to use these models for operational prediction of mesoscale convective systems.

  15. Teaching "Instant Experience" with Graphical Model Validation Techniques

    ERIC Educational Resources Information Center

    Ekstrøm, Claus Thorn

    2014-01-01

    Graphical model validation techniques for linear normal models are often used to check the assumptions underlying a statistical model. We describe an approach to provide "instant experience" in looking at a graphical model validation plot, so it becomes easier to validate if any of the underlying assumptions are violated.

  16. Validation of Kp Estimation and Prediction Models

    NASA Astrophysics Data System (ADS)

    McCollough, J. P., II; Young, S. L.; Frey, W.

    2014-12-01

    Specifification and forecast of geomagnetic indices is an important capability for space weather operations. The University Partnering for Operational Support (UPOS) effort at the Applied Physics Laboratory of Johns Hopkins University (JHU/APL) produced many space weather models, including the Kp Predictor and Kp Estimator. We perform a validation of index forecast products against definitive indices computed by the Deutches GeoForschungsZentstrum Potsdam (GFZ). We compute continuous predictant skill scores, as well as 2x2 contingency tables and associated scalar quantities for different index thresholds. We also compute a skill score against a nowcast persistence model. We discuss various sources of error for the models and how they may potentially be improved.

  17. Plasma Reactor Modeling and Validation Experiments

    NASA Technical Reports Server (NTRS)

    Meyyappan, M.; Bose, D.; Hash, D.; Hwang, H.; Cruden, B.; Sharma, S. P.; Rao, M. V. V. S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Plasma processing is a key processing stop in integrated circuit manufacturing. Low pressure, high density plum reactors are widely used for etching and deposition. Inductively coupled plasma (ICP) source has become popular recently in many processing applications. In order to accelerate equipment and process design, an understanding of the physics and chemistry, particularly, plasma power coupling, plasma and processing uniformity and mechanism is important. This understanding is facilitated by comprehensive modeling and simulation as well as plasma diagnostics to provide the necessary data for model validation which are addressed in this presentation. We have developed a complete code for simulating an ICP reactor and the model consists of transport of electrons, ions, and neutrals, Poisson's equation, and Maxwell's equation along with gas flow and energy equations. Results will be presented for chlorine and fluorocarbon plasmas and compared with data from Langmuir probe, mass spectrometry and FTIR.

  18. Concepts of Model Verification and Validation

    SciTech Connect

    B.H.Thacker; S.W.Doebling; F.M.Hemez; M.C. Anderson; J.E. Pepin; E.A. Rodriguez

    2004-10-30

    Model verification and validation (V&V) is an enabling methodology for the development of computational models that can be used to make engineering predictions with quantified confidence. Model V&V procedures are needed by government and industry to reduce the time, cost, and risk associated with full-scale testing of products, materials, and weapon systems. Quantifying the confidence and predictive accuracy of model calculations provides the decision-maker with the information necessary for making high-consequence decisions. The development of guidelines and procedures for conducting a model V&V program are currently being defined by a broad spectrum of researchers. This report reviews the concepts involved in such a program. Model V&V is a current topic of great interest to both government and industry. In response to a ban on the production of new strategic weapons and nuclear testing, the Department of Energy (DOE) initiated the Science-Based Stockpile Stewardship Program (SSP). An objective of the SSP is to maintain a high level of confidence in the safety, reliability, and performance of the existing nuclear weapons stockpile in the absence of nuclear testing. This objective has challenged the national laboratories to develop high-confidence tools and methods that can be used to provide credible models needed for stockpile certification via numerical simulation. There has been a significant increase in activity recently to define V&V methods and procedures. The U.S. Department of Defense (DoD) Modeling and Simulation Office (DMSO) is working to develop fundamental concepts and terminology for V&V applied to high-level systems such as ballistic missile defense and battle management simulations. The American Society of Mechanical Engineers (ASME) has recently formed a Standards Committee for the development of V&V procedures for computational solid mechanics models. The Defense Nuclear Facilities Safety Board (DNFSB) has been a proponent of model V&V for all

  19. Validated predictive modelling of the environmental resistome

    PubMed Central

    Amos, Gregory CA; Gozzard, Emma; Carter, Charlotte E; Mead, Andrew; Bowes, Mike J; Hawkey, Peter M; Zhang, Lihong; Singer, Andrew C; Gaze, William H; Wellington, Elizabeth M H

    2015-01-01

    Multi-drug-resistant bacteria pose a significant threat to public health. The role of the environment in the overall rise in antibiotic-resistant infections and risk to humans is largely unknown. This study aimed to evaluate drivers of antibiotic-resistance levels across the River Thames catchment, model key biotic, spatial and chemical variables and produce predictive models for future risk assessment. Sediment samples from 13 sites across the River Thames basin were taken at four time points across 2011 and 2012. Samples were analysed for class 1 integron prevalence and enumeration of third-generation cephalosporin-resistant bacteria. Class 1 integron prevalence was validated as a molecular marker of antibiotic resistance; levels of resistance showed significant geospatial and temporal variation. The main explanatory variables of resistance levels at each sample site were the number, proximity, size and type of surrounding wastewater-treatment plants. Model 1 revealed treatment plants accounted for 49.5% of the variance in resistance levels. Other contributing factors were extent of different surrounding land cover types (for example, Neutral Grassland), temporal patterns and prior rainfall; when modelling all variables the resulting model (Model 2) could explain 82.9% of variations in resistance levels in the whole catchment. Chemical analyses correlated with key indicators of treatment plant effluent and a model (Model 3) was generated based on water quality parameters (contaminant and macro- and micro-nutrient levels). Model 2 was beta tested on independent sites and explained over 78% of the variation in integron prevalence showing a significant predictive ability. We believe all models in this study are highly useful tools for informing and prioritising mitigation strategies to reduce the environmental resistome. PMID:25679532

  20. Validated predictive modelling of the environmental resistome.

    PubMed

    Amos, Gregory C A; Gozzard, Emma; Carter, Charlotte E; Mead, Andrew; Bowes, Mike J; Hawkey, Peter M; Zhang, Lihong; Singer, Andrew C; Gaze, William H; Wellington, Elizabeth M H

    2015-06-01

    Multi-drug-resistant bacteria pose a significant threat to public health. The role of the environment in the overall rise in antibiotic-resistant infections and risk to humans is largely unknown. This study aimed to evaluate drivers of antibiotic-resistance levels across the River Thames catchment, model key biotic, spatial and chemical variables and produce predictive models for future risk assessment. Sediment samples from 13 sites across the River Thames basin were taken at four time points across 2011 and 2012. Samples were analysed for class 1 integron prevalence and enumeration of third-generation cephalosporin-resistant bacteria. Class 1 integron prevalence was validated as a molecular marker of antibiotic resistance; levels of resistance showed significant geospatial and temporal variation. The main explanatory variables of resistance levels at each sample site were the number, proximity, size and type of surrounding wastewater-treatment plants. Model 1 revealed treatment plants accounted for 49.5% of the variance in resistance levels. Other contributing factors were extent of different surrounding land cover types (for example, Neutral Grassland), temporal patterns and prior rainfall; when modelling all variables the resulting model (Model 2) could explain 82.9% of variations in resistance levels in the whole catchment. Chemical analyses correlated with key indicators of treatment plant effluent and a model (Model 3) was generated based on water quality parameters (contaminant and macro- and micro-nutrient levels). Model 2 was beta tested on independent sites and explained over 78% of the variation in integron prevalence showing a significant predictive ability. We believe all models in this study are highly useful tools for informing and prioritising mitigation strategies to reduce the environmental resistome. PMID:25679532

  1. Model-Based Method for Sensor Validation

    NASA Technical Reports Server (NTRS)

    Vatan, Farrokh

    2012-01-01

    Fault detection, diagnosis, and prognosis are essential tasks in the operation of autonomous spacecraft, instruments, and in situ platforms. One of NASA s key mission requirements is robust state estimation. Sensing, using a wide range of sensors and sensor fusion approaches, plays a central role in robust state estimation, and there is a need to diagnose sensor failure as well as component failure. Sensor validation can be considered to be part of the larger effort of improving reliability and safety. The standard methods for solving the sensor validation problem are based on probabilistic analysis of the system, from which the method based on Bayesian networks is most popular. Therefore, these methods can only predict the most probable faulty sensors, which are subject to the initial probabilities defined for the failures. The method developed in this work is based on a model-based approach and provides the faulty sensors (if any), which can be logically inferred from the model of the system and the sensor readings (observations). The method is also more suitable for the systems when it is hard, or even impossible, to find the probability functions of the system. The method starts by a new mathematical description of the problem and develops a very efficient and systematic algorithm for its solution. The method builds on the concepts of analytical redundant relations (ARRs).

  2. Integrated Medical Model Verification, Validation, and Credibility

    NASA Technical Reports Server (NTRS)

    Walton, Marlei; Kerstman, Eric; Foy, Millennia; Shah, Ronak; Saile, Lynn; Boley, Lynn; Butler, Doug; Myers, Jerry

    2014-01-01

    The Integrated Medical Model (IMM) was designed to forecast relative changes for a specified set of crew health and mission success risk metrics by using a probabilistic (stochastic process) model based on historical data, cohort data, and subject matter expert opinion. A probabilistic approach is taken since exact (deterministic) results would not appropriately reflect the uncertainty in the IMM inputs. Once the IMM was conceptualized, a plan was needed to rigorously assess input information, framework and code, and output results of the IMM, and ensure that end user requests and requirements were considered during all stages of model development and implementation. METHODS: In 2008, the IMM team developed a comprehensive verification and validation (VV) plan, which specified internal and external review criteria encompassing 1) verification of data and IMM structure to ensure proper implementation of the IMM, 2) several validation techniques to confirm that the simulation capability of the IMM appropriately represents occurrences and consequences of medical conditions during space missions, and 3) credibility processes to develop user confidence in the information derived from the IMM. When the NASA-STD-7009 (7009) was published, the IMM team updated their verification, validation, and credibility (VVC) project plan to meet 7009 requirements and include 7009 tools in reporting VVC status of the IMM. RESULTS: IMM VVC updates are compiled recurrently and include 7009 Compliance and Credibility matrices, IMM VV Plan status, and a synopsis of any changes or updates to the IMM during the reporting period. Reporting tools have evolved over the lifetime of the IMM project to better communicate VVC status. This has included refining original 7009 methodology with augmentation from the NASA-STD-7009 Guidance Document. End user requests and requirements are being satisfied as evidenced by ISS Program acceptance of IMM risk forecasts, transition to an operational model and

  3. Boron-10 Lined Proportional Counter Model Validation

    SciTech Connect

    Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

    2012-06-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

  4. Doubtful outcome of the validation of the Rome II questionnaire: validation of a symptom based diagnostic tool

    PubMed Central

    2009-01-01

    Background Questionnaires are used in research and clinical practice. For gastrointestinal complaints the Rome II questionnaire is internationally known but not validated. The aim of this study was to validate a printed and a computerized version of Rome II, translated into Swedish. Results from various analyses are reported. Methods Volunteers from a population based colonoscopy study were included (n = 1011), together with patients seeking general practice (n = 45) and patients visiting a gastrointestinal specialists' clinic (n = 67). The questionnaire consists of 38 questions concerning gastrointestinal symptoms and complaints. Diagnoses are made after a special code. Our validation included analyses of the translation, feasibility, predictability, reproducibility and reliability. Kappa values and overall agreement were measured. The factor structures were confirmed using a principal component analysis and Cronbach's alpha was used to test the internal consistency. Results and Discussion Translation and back translation showed good agreement. The questionnaire was easy to understand and use. The reproducibility test showed kappa values of 0.60 for GERS, 0.52 for FD, and 0.47 for IBS. Kappa values and overall agreement for the predictability when the diagnoses by the questionnaire were compared to the diagnoses by the clinician were 0.26 and 90% for GERS, 0.18 and 85% for FD, and 0.49 and 86% for IBS. Corresponding figures for the agreement between the printed and the digital version were 0.50 and 92% for GERS, 0.64 and 95% for FD, and 0.76 and 95% for IBS. Cronbach's alpha coefficient for GERS was 0.75 with a span per item of 0.71 to 0.76. For FD the figures were 0.68 and 0.54 to 0.70 and for IBS 0.61 and 0.56 to 0.66. The Rome II questionnaire has never been thoroughly validated before even if diagnoses made by the Rome criteria have been compared to diagnoses made in clinical practice. Conclusion The accuracy of the Swedish version of the Rome II is of

  5. Concurrent Validity of the Online Version of the Keirsey Temperament Sorter II.

    ERIC Educational Resources Information Center

    Kelly, Kevin R.; Jugovic, Heidi

    2001-01-01

    Data from the Keirsey Temperament Sorter II online instrument and Myers Briggs Type Indicator (MBTI) for 203 college freshmen were analyzed. Positive correlations appeared between the concurrent MBTI and Keirsey measures of psychological type, giving preliminary support to the validity of the online version of Keirsey. (Contains 28 references.)…

  6. Recommendations for the determination of valid mode II fracture toughnesses K{sub IIc}

    SciTech Connect

    Hiese, W.; Kalthoff, J.F.

    1999-07-01

    From a discussion of the sizes of the plastic zones at the tip of a crack under shear (Mode II) and tensile (Mode I) conditions of loading, hypotheses on specimen size requirements are derived for determining valid values of the shear fracture toughness K{sub IIc}. The following conclusions are drawn: The minimum specimen thickness for a K{sub IIc} test can be smaller, but the minimum in-plane specimen dimensions should be larger than for a K{sub Ic} test. For verification of these hypotheses, Mode II and additionally Mode I fracture toughnesses were determined for the aluminum alloy 7075 and the tool steel 90 MnCrV 8. Measurements were performed with specimens of different sizes with respect to the size of the crack tip plastic zones. The obtained data are in good agreement with the derived criteria for measuring Mode II fracture toughnesses K{sub IIc} and confirm their validity.

  7. Unit testing, model validation, and biological simulation

    PubMed Central

    Watts, Mark D.; Ghayoomie, S. Vahid; Larson, Stephen D.; Gerkin, Richard C.

    2016-01-01

    The growth of the software industry has gone hand in hand with the development of tools and cultural practices for ensuring the reliability of complex pieces of software. These tools and practices are now acknowledged to be essential to the management of modern software. As computational models and methods have become increasingly common in the biological sciences, it is important to examine how these practices can accelerate biological software development and improve research quality. In this article, we give a focused case study of our experience with the practices of unit testing and test-driven development in OpenWorm, an open-science project aimed at modeling Caenorhabditis elegans. We identify and discuss the challenges of incorporating test-driven development into a heterogeneous, data-driven project, as well as the role of model validation tests, a category of tests unique to software which expresses scientific models.

  8. Validation and application of the SCALP model

    NASA Astrophysics Data System (ADS)

    Smith, D. A. J.; Martin, C. E.; Saunders, C. J.; Smith, D. A.; Stokes, P. H.

    The Satellite Collision Assessment for the UK Licensing Process (SCALP) model was first introduced in a paper presented at IAC 2003. As a follow-on, this paper details the steps taken to validate the model and describes some of its applications. SCALP was developed for the British National Space Centre (BNSC) to support liability assessments as part of the UK's satellite license application process. Specifically, the model determines the collision risk that a satellite will pose to other orbiting objects during both its operational and post-mission phases. To date SCALP has been used to assess several LEO and GEO satellites for BNSC, and subsequently to provide the necessary technical basis for licenses to be issued. SCALP utilises the current population of operational satellites residing in LEO and GEO (extracted from ESA's DISCOS database) as a starting point. Realistic orbital dynamics, including the approximate simulation of generic GEO station-keeping strategies are used to propagate the objects over time. The method takes into account all of the appropriate orbit perturbations for LEO and GEO altitudes and allows rapid run times for multiple objects over time periods of many years. The orbit of a target satellite is also propagated in a similar fashion. During these orbital evolutions, a collision prediction and close approach algorithm assesses the collision risk posed to the satellite population. To validate SCALP, specific cases were set up to enable the comparison of collision risk results with other established models, such as the ESA MASTER model. Additionally, the propagation of operational GEO satellites within SCALP was compared with the expected behaviour of controlled GEO objects. The sensitivity of the model to changing the initial conditions of the target satellite such as semi-major axis and inclination has also been demonstrated. A further study shows the effect of including extra objects from the GTO population (which can pass through the LEO

  9. Validation of Arabic and English versions of the ARSMA-II Acculturation Rating Scale.

    PubMed

    Jadalla, Ahlam; Lee, Jerry

    2015-02-01

    To translate and adapt the Acculturation Rating Scale of Mexican-Americans II (ARSMA-II) for Arab Americans. A multistage translation process followed by a pilot and a large study. The translated and adapted versions, Acculturation Rating Scale for Arabic Americans-II Arabic and English (ARSAA-IIA, ARSAA-IIE), were validated in a sample of 297 Arab Americans. Factor analyses with principal axis factoring extractions and direct oblimin rotations were used to identify the underlying structure of ARSAA-II. Factor analysis confirmed the underlying structure of ARSAA-II and produced two interpretable factors labeled as 'Attraction to American Culture' (AAmC) and 'Attraction to Arabic Culture' (AArC). The Cronbach's alphas of AAmC and AArC were .89 and .85 respectively. Findings support ARSAA-II A & E to assess acculturation among Arab Americans. The emergent factors of ARSAA-II support the theoretical structure of the original ARSMA-II tool and show high internal consistency. PMID:23934518

  10. Full-Scale Cookoff Model Validation Experiments

    SciTech Connect

    McClelland, M A; Rattanapote, M K; Heimdahl, E R; Erikson, W E; Curran, P O; Atwood, A I

    2003-11-25

    This paper presents the experimental results of the third and final phase of a cookoff model validation effort. In this phase of the work, two generic Heavy Wall Penetrators (HWP) were tested in two heating orientations. Temperature and strain gage data were collected over the entire test period. Predictions for time and temperature of reaction were made prior to release of the live data. Predictions were comparable to the measured values and were highly dependent on the established boundary conditions. Both HWP tests failed at a weld located near the aft closure of the device. More than 90 percent of unreacted explosive was recovered in the end heated experiment and less than 30 percent recovered in the side heated test.

  11. Some useful statistical methods for model validation.

    PubMed Central

    Marcus, A H; Elias, R W

    1998-01-01

    Although formal hypothesis tests provide a convenient framework for displaying the statistical results of empirical comparisons, standard tests should not be used without consideration of underlying measurement error structure. As part of the validation process, predictions of individual blood lead concentrations from models with site-specific input parameters are often compared with blood lead concentrations measured in field studies that also report lead concentrations in environmental media (soil, dust, water, paint) as surrogates for exposure. Measurements of these environmental media are subject to several sources of variability, including temporal and spatial sampling, sample preparation and chemical analysis, and data entry or recording. Adjustments for measurement error must be made before statistical tests can be used to empirically compare environmental data with model predictions. This report illustrates the effect of measurement error correction using a real dataset of child blood lead concentrations for an undisclosed midwestern community. We illustrate both the apparent failure of some standard regression tests and the success of adjustment of such tests for measurement error using the SIMEX (simulation-extrapolation) procedure. This procedure adds simulated measurement error to model predictions and then subtracts the total measurement error, analogous to the method of standard additions used by analytical chemists. Images Figure 1 Figure 3 PMID:9860913

  12. Diurnal ocean surface layer model validation

    NASA Technical Reports Server (NTRS)

    Hawkins, Jeffrey D.; May, Douglas A.; Abell, Fred, Jr.

    1990-01-01

    The diurnal ocean surface layer (DOSL) model at the Fleet Numerical Oceanography Center forecasts the 24-hour change in a global sea surface temperatures (SST). Validating the DOSL model is a difficult task due to the huge areas involved and the lack of in situ measurements. Therefore, this report details the use of satellite infrared multichannel SST imagery to provide day and night SSTs that can be directly compared to DOSL products. This water-vapor-corrected imagery has the advantages of high thermal sensitivity (0.12 C), large synoptic coverage (nearly 3000 km across), and high spatial resolution that enables diurnal heating events to be readily located and mapped. Several case studies in the subtropical North Atlantic readily show that DOSL results during extreme heating periods agree very well with satellite-imagery-derived values in terms of the pattern of diurnal warming. The low wind and cloud-free conditions necessary for these events to occur lend themselves well to observation via infrared imagery. Thus, the normally cloud-limited aspects of satellite imagery do not come into play for these particular environmental conditions. The fact that the DOSL model does well in extreme events is beneficial from the standpoint that these cases can be associated with the destruction of the surface acoustic duct. This so-called afternoon effect happens as the afternoon warming of the mixed layer disrupts the sound channel and the propagation of acoustic energy.

  13. Outward Bound Outcome Model Validation and Multilevel Modeling

    ERIC Educational Resources Information Center

    Luo, Yuan-Chun

    2011-01-01

    This study was intended to measure construct validity for the Outward Bound Outcomes Instrument (OBOI) and to predict outcome achievement from individual characteristics and course attributes using multilevel modeling. A sample of 2,340 participants was collected by Outward Bound USA between May and September 2009 using the OBOI. Two phases of…

  14. Simultaneous heat and water model: Model use, calibration and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A discussion of calibration and validation procedures used for the Simultaneous Heat and Water model is presented. Three calibration approaches are presented and compared for simulating soil water content. Approaches included a stepwise local search methodology, trial-and-error calibration, and an...

  15. Validation of HEDR models. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Napier, B.A.; Simpson, J.C.; Eslinger, P.W.; Ramsdell, J.V. Jr.; Thiede, M.E.; Walters, W.H.

    1994-05-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project has developed a set of computer models for estimating the possible radiation doses that individuals may have received from past Hanford Site operations. This document describes the validation of these models. In the HEDR Project, the model validation exercise consisted of comparing computational model estimates with limited historical field measurements and experimental measurements that are independent of those used to develop the models. The results of any one test do not mean that a model is valid. Rather, the collection of tests together provide a level of confidence that the HEDR models are valid.

  16. End-to-end modelling of He II flow systems

    NASA Technical Reports Server (NTRS)

    Mord, A. J.; Snyder, H. A.; Newell, D. A.

    1992-01-01

    A practical computer code has been developed which uses the accepted two-fluid model to simulate He II flow in complicated systems. The full set of equations are used, retaining the coupling between the pressure, temperature and velocity fields. This permits modeling He II flow over the full range of conditions, from strongly or weakly driven flow through large pipes, narrow channels and porous media. The system may include most of the components used in modern superfluid flow systems: non-ideal thermomechanical pumps, tapered sections, constrictions, lines with heated side walls and heat exchangers. The model is validated by comparison with published experimental data. It is applied to a complex system to show some of the non-intuitive feedback effects that can occur. This code is ready to be used as a design tool for practical applications of He II. It can also be used for the design of He II experiments and as a tool for comparison of experimental data with the standard two-fluid model.

  17. Validating agent based models through virtual worlds.

    SciTech Connect

    Lakkaraju, Kiran; Whetzel, Jonathan H.; Lee, Jina; Bier, Asmeret Brooke; Cardona-Rivera, Rogelio E.; Bernstein, Jeremy Ray Rhythm

    2014-01-01

    As the US continues its vigilance against distributed, embedded threats, understanding the political and social structure of these groups becomes paramount for predicting and dis- rupting their attacks. Agent-based models (ABMs) serve as a powerful tool to study these groups. While the popularity of social network tools (e.g., Facebook, Twitter) has provided extensive communication data, there is a lack of ne-grained behavioral data with which to inform and validate existing ABMs. Virtual worlds, in particular massively multiplayer online games (MMOG), where large numbers of people interact within a complex environ- ment for long periods of time provide an alternative source of data. These environments provide a rich social environment where players engage in a variety of activities observed between real-world groups: collaborating and/or competing with other groups, conducting battles for scarce resources, and trading in a market economy. Strategies employed by player groups surprisingly re ect those seen in present-day con icts, where players use diplomacy or espionage as their means for accomplishing their goals. In this project, we propose to address the need for ne-grained behavioral data by acquiring and analyzing game data a commercial MMOG, referred to within this report as Game X. The goals of this research were: (1) devising toolsets for analyzing virtual world data to better inform the rules that govern a social ABM and (2) exploring how virtual worlds could serve as a source of data to validate ABMs established for analogous real-world phenomena. During this research, we studied certain patterns of group behavior to compliment social modeling e orts where a signi cant lack of detailed examples of observed phenomena exists. This report outlines our work examining group behaviors that underly what we have termed the Expression-To-Action (E2A) problem: determining the changes in social contact that lead individuals/groups to engage in a particular behavior

  18. The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters

    SciTech Connect

    Lee, Y.S.; Beers, T.C.; Sivarani, T.; Johnson, J.A.; An, D.; Wilhelm, R.; Prieto, C.Allende; Koesterke, L.; Re Fiorentin, P.; Bailer-Jones, C.A.L.; Norris, J.E.

    2007-10-01

    The authors validate the performance and accuracy of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) by comparing derived overall metallicities and radial velocities from selected likely members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-1) and its first extension (SDSS-II/SEGUE) are used to determine stellar radial velocities and atmospheric parameter estimates for stars in these clusters. Based on the scatter in the metallicities derived for the members of each cluster, they quantify the typical uncertainty of the SSPP values, {sigma}([Fe/H]) = 0.13 dex for stars in the range of 4500 K {le} T{sub eff} {le} 7500 K and 2.0 {le} log g {le} 5.0, at least over the metallicity interval spanned by the clusters studied (-2.3 {le} [Fe/H] < 0). The surface gravities and effective temperatures derived by the SSPP are also compared with those estimated from the comparison of the color-magnitude diagrams with stellar evolution models; they find satisfactory agreement. At present, the SSPP underestimates [Fe/H] for near-solar-metallicity stars, represented by members of M 67 in this study, by {approx} 0.3 dex.

  19. Geochemistry Model Validation Report: Material Degradation and Release Model

    SciTech Connect

    H. Stockman

    2001-09-28

    The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17).

  20. Tutorial review on validation of liquid chromatography-mass spectrometry methods: part II.

    PubMed

    Kruve, Anneli; Rebane, Riin; Kipper, Karin; Oldekop, Maarja-Liisa; Evard, Hanno; Herodes, Koit; Ravio, Pekka; Leito, Ivo

    2015-04-22

    This is the part II of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC-MS) and discuss specific issues that arise with MS (and MS-MS) detection in LC (as opposed to the "conventional" detectors). The Part II starts with briefly introducing the main quantitation methods and then addresses the performance related to quantification: linearity of signal, sensitivity, precision, trueness, accuracy, stability and measurement uncertainty. The last section is devoted to practical considerations in validation. With every performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to handle it, specifically in the case of LC-MS methods. PMID:25819784

  1. Micromachined accelerometer design, modeling and validation

    SciTech Connect

    Davies, B.R.; Bateman, V.I.; Brown, F.A.; Montague, S.; Murray, J.R.; Rey, D.; Smith, J.H.

    1998-04-01

    Micromachining technologies enable the development of low-cost devices capable of sensing motion in a reliable and accurate manner. The development of various surface micromachined accelerometers and gyroscopes to sense motion is an ongoing activity at Sandia National Laboratories. In addition, Sandia has developed a fabrication process for integrating both the micromechanical structures and microelectronics circuitry of Micro-Electro-Mechanical Systems (MEMS) on the same chip. This integrated surface micromachining process provides substantial performance and reliability advantages in the development of MEMS accelerometers and gyros. A Sandia MEMS team developed a single-axis, micromachined silicon accelerometer capable of surviving and measuring very high accelerations, up to 50,000 times the acceleration due to gravity or 50 k-G (actually measured to 46,000 G). The Sandia integrated surface micromachining process was selected for fabrication of the sensor due to the extreme measurement sensitivity potential associated with integrated microelectronics. Measurement electronics capable of measuring at to Farad (10{sup {minus}18} Farad) changes in capacitance were required due to the very small accelerometer proof mass (< 200 {times} 10{sup {minus}9} gram) used in this surface micromachining process. The small proof mass corresponded to small sensor deflections which in turn required very sensitive electronics to enable accurate acceleration measurement over a range of 1 to 50 k-G. A prototype sensor, based on a suspended plate mass configuration, was developed and the details of the design, modeling, and validation of the device will be presented in this paper. The device was analyzed using both conventional lumped parameter modeling techniques and finite element analysis tools. The device was tested and performed well over its design range.

  2. External validation of a Cox prognostic model: principles and methods

    PubMed Central

    2013-01-01

    Background A prognostic model should not enter clinical practice unless it has been demonstrated that it performs a useful role. External validation denotes evaluation of model performance in a sample independent of that used to develop the model. Unlike for logistic regression models, external validation of Cox models is sparsely treated in the literature. Successful validation of a model means achieving satisfactory discrimination and calibration (prediction accuracy) in the validation sample. Validating Cox models is not straightforward because event probabilities are estimated relative to an unspecified baseline function. Methods We describe statistical approaches to external validation of a published Cox model according to the level of published information, specifically (1) the prognostic index only, (2) the prognostic index together with Kaplan-Meier curves for risk groups, and (3) the first two plus the baseline survival curve (the estimated survival function at the mean prognostic index across the sample). The most challenging task, requiring level 3 information, is assessing calibration, for which we suggest a method of approximating the baseline survival function. Results We apply the methods to two comparable datasets in primary breast cancer, treating one as derivation and the other as validation sample. Results are presented for discrimination and calibration. We demonstrate plots of survival probabilities that can assist model evaluation. Conclusions Our validation methods are applicable to a wide range of prognostic studies and provide researchers with a toolkit for external validation of a published Cox model. PMID:23496923

  3. Techniques and Issues in Agent-Based Modeling Validation

    SciTech Connect

    Pullum, Laura L; Cui, Xiaohui

    2012-01-01

    Validation of simulation models is extremely important. It ensures that the right model has been built and lends confidence to the use of that model to inform critical decisions. Agent-based models (ABM) have been widely deployed in different fields for studying the collective behavior of large numbers of interacting agents. However, researchers have only recently started to consider the issues of validation. Compared to other simulation models, ABM has many differences in model development, usage and validation. An ABM is inherently easier to build than a classical simulation, but more difficult to describe formally since they are closer to human cognition. Using multi-agent models to study complex systems has attracted criticisms because of the challenges involved in their validation [1]. In this report, we describe the challenge of ABM validation and present a novel approach we recently developed for an ABM system.

  4. Model for Use of Sociometry to Validate Attitude Measures.

    ERIC Educational Resources Information Center

    McGuiness, Thomas P.; Stank, Peggy L.

    A study concerning the development and validation of an instrument intended to measure Goal II of quality education is presented. This goal is that quality education should help every child acquire understanding and appreciation of persons belonging to social, cultural and ethnic groups different from his own. The rationale for measurement…

  5. A methodology for validating numerical ground water models.

    PubMed

    Hassan, Ahmed E

    2004-01-01

    Ground water validation is one of the most challenging issues facing modelers and hydrogeologists. Increased complexity in ground water models has created a gap between model predictions and the ability to validate or build confidence in predictions. Specific procedures and tests that can be easily adapted and applied to determine the validity of site-specific ground water models do not exist. This is true for both deterministic and stochastic models, with stochastic models posing the more difficult validation problem. The objective of this paper is to propose a general validation approach that addresses important issues recognized in previous validation studies, conferences, and symposia. The proposed method links the processes for building, calibrating, evaluating, and validating models in an iterative loop. The approach focuses on using collected validation data to reduce uncertainty in the model and narrow the range of possible outcomes. This method is designed for stochastic numerical models utilizing Monte Carlo simulation approaches, but it can be easily adapted for deterministic models. The proposed methodology relies on the premise that absolute validity is not theoretically possible, nor is it a regulatory requirement. Rather, the proposed methodology highlights the importance of testing various aspects of the model and using diverse statistical tools for rigorous checking and confidence building in the model and its predictions. It is this confidence that will encourage regulators and the public to accept decisions based on the model predictions. This validation approach will be applied to a model, described in this paper, dealing with an underground nuclear test site in rural Nevada. PMID:15161152

  6. System Advisor Model: Flat Plate Photovoltaic Performance Modeling Validation Report

    SciTech Connect

    Freeman, J.; Whitmore, J.; Kaffine, L.; Blair, N.; Dobos, A. P.

    2013-12-01

    The System Advisor Model (SAM) is a free software tool that performs detailed analysis of both system performance and system financing for a variety of renewable energy technologies. This report provides detailed validation of the SAM flat plate photovoltaic performance model by comparing SAM-modeled PV system generation data to actual measured production data for nine PV systems ranging from 75 kW to greater than 25 MW in size. The results show strong agreement between SAM predictions and field data, with annualized prediction error below 3% for all fixed tilt cases and below 8% for all one axis tracked cases. The analysis concludes that snow cover and system outages are the primary sources of disagreement, and other deviations resulting from seasonal biases in the irradiation models and one axis tracking issues are discussed in detail.

  7. SAGE III Aerosol Extinction Validation in the Arctic Winter: Comparisons with SAGE II and POAM III

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.; Poole, L. R.; Randall, C. E.

    2007-01-01

    The use of SAGE III multiwavelength aerosol extinction coefficient measurements to infer PSC type is contingent on the robustness of both the extinction magnitude and its spectral variation. Past validation with SAGE II and other similar measurements has shown that the SAGE III extinction coefficient measurements are reliable though the comparisons have been greatly weighted toward measurements made at mid-latitudes. Some aerosol comparisons made in the Arctic winter as a part of SOLVE II suggested that SAGE III values, particularly at longer wavelengths, are too small with the implication that both the magnitude and the wavelength dependence are not reliable. Comparisons with POAM III have also suggested a similar discrepancy. Herein, we use SAGE II data as a common standard for comparison of SAGE III and POAM III measurements in the Arctic winters of 2002/2003 through 2004/2005. During the winter, SAGE II measurements are made infrequently at the same latitudes as these instruments. We have mitigated this problem through the use potential vorticity as a spatial coordinate and thus greatly increased the number of coincident events. We find that SAGE II and III extinction coefficient measurements show a high degree of compatibility at both 1020 nm and 450 nm except a 10-20% bias at both wavelengths. In addition, the 452 to 1020-nm extinction ratio shows a consistent bias of approx. 30% throughout the lower stratosphere. We also find that SAGE II and POAM III are on average consistent though the comparisons show a much higher variability and larger bias than SAGE II/III comparisons. In addition, we find that the two data sets are not well correlated below 18 km. Overall, we find both the extinction values and the spectral dependence from SAGE III are robust and we find no evidence of a significant defect within the Arctic vortex.

  8. Homology modeling, binding site identification and docking study of human angiotensin II type I (Ang II-AT1) receptor.

    PubMed

    Vyas, Vivek K; Ghate, Manjunath; Patel, Kinjal; Qureshi, Gulamnizami; Shah, Surmil

    2015-08-01

    Ang II-AT1 receptors play an important role in mediating virtually all of the physiological actions of Ang II. Several drugs (SARTANs) are available, which can block the AT1 receptor effectively and lower the blood pressure in the patients with hypertension. Currently, there is no experimental Ang II-AT1 structure available; therefore, in this study we modeled Ang II-AT1 receptor structure using homology modeling followed by identification and characterization of binding sites and thereby assessing druggability of the receptor. Homology models were constructed using MODELLER and I-TASSER server, refined and validated using PROCHECK in which 96.9% of 318 residues were present in the favoured regions of the Ramachandran plots. Various Ang II-AT1 receptor antagonist drugs are available in the market as antihypertensive drug, so we have performed docking study with the binding site prediction algorithms to predict different binding pockets on the modeled proteins. The identification of 3D structures and binding sites for various known drugs will guide us for the structure-based drug design of novel compounds as Ang II-AT1 receptor antagonists for the treatment of hypertension. PMID:26349961

  9. Development and Validation of the Juvenile Sexual Offense Recidivism Risk Assessment Tool-II.

    PubMed

    Epperson, Douglas L; Ralston, Christopher A

    2015-12-01

    This article describes the development and initial validation of the Juvenile Sexual Offense Recidivism Risk Assessment Tool-II (JSORRAT-II). Potential predictor variables were extracted from case file information for an exhaustive sample of 636 juveniles in Utah who sexually offended between 1990 and 1992. Simultaneous and hierarchical logistic regression analyses were used to identify the group of variables that was most predictive of subsequent juvenile sexual recidivism. A simple categorical scoring system was applied to these variables without meaningful loss of accuracy in the development sample for any sexual (area under the curve [AUC] = .89) and sexually violent (AUC = .89) juvenile recidivism. The JSORRAT-II was cross-validated on an exhaustive sample of 566 juveniles who had sexually offended in Utah in 1996 and 1997. Reliability of scoring the tool across five coders was quite high (intraclass correlation coefficient [ICC] = .96). Relative to the development sample, however, there was considerable shrinkage in the indices of predictive accuracy for any sexual (AUC = .65) and sexually violent (AUC = .65) juvenile recidivism. The reduced level of accuracy was not explained by severity of the index sexual offense, time at risk, or missing data. Capitalization on chance and other explanations for the possible reduction in predictive accuracy are explored, and potential uses and limitations of the tool are discussed. PMID:24492618

  10. A comprehensive model for piezoceramic actuators: modelling, validation and application

    NASA Astrophysics Data System (ADS)

    Quant, Mario; Elizalde, Hugo; Flores, Abiud; Ramírez, Ricardo; Orta, Pedro; Song, Gangbing

    2009-12-01

    This paper presents a comprehensive model for piezoceramic actuators (PAs), which accounts for hysteresis, non-linear electric field and dynamic effects. The hysteresis model is based on the widely used general Maxwell slip model, while an enhanced electro-mechanical non-linear model replaces the linear constitutive equations commonly used. Further on, a linear second order model compensates the frequency response of the actuator. Each individual model is fully characterized from experimental data yielded by a specific PA, then incorporated into a comprehensive 'direct' model able to determine the output strain based on the applied input voltage, fully compensating the aforementioned effects, where the term 'direct' represents an electrical-to-mechanical operating path. The 'direct' model was implemented in a Matlab/Simulink environment and successfully validated via experimental results, exhibiting higher accuracy and simplicity than many published models. This simplicity would allow a straightforward inclusion of other behaviour such as creep, ageing, material non-linearity, etc, if such parameters are important for a particular application. Based on the same formulation, two other models are also presented: the first is an 'alternate' model intended to operate within a force-controlled scheme (instead of a displacement/position control), thus able to capture the complex mechanical interactions occurring between a PA and its host structure. The second development is an 'inverse' model, able to operate within an open-loop control scheme, that is, yielding a 'linearized' PA behaviour. The performance of the developed models is demonstrated via a numerical sample case simulated in Matlab/Simulink, consisting of a PA coupled to a simple mechanical system, aimed at shifting the natural frequency of the latter.

  11. Searching For Valid Psychiatric Phenotypes: Discrete Latent Variable Models

    PubMed Central

    Leoutsakos, Jeannie-Marie S.; Zandi, Peter P.; Bandeen-Roche, Karen; Lyketsos, Constantine G.

    2010-01-01

    Introduction A primary challenge in psychiatric genetics is the lack of a completely validated system of classification for mental disorders. Appropriate statistical methods are needed to empirically derive more homogenous disorder subtypes. Methods Using the framework of Robins & Guze’s (1970) five phases, latent variable models to derive and validate diagnostic groups are described. A process of iterative validation is proposed through which refined phenotypes would facilitate research on genetics, pathogenesis, and treatment, which would in turn aid further refinement of disorder definitions. Conclusions Latent variable methods are useful tools for defining and validating psychiatric phenotypes. Further methodological research should address sample size issues and application to iterative validation. PMID:20187060

  12. Three Dimensional Vapor Intrusion Modeling: Model Validation and Uncertainty Analysis

    NASA Astrophysics Data System (ADS)

    Akbariyeh, S.; Patterson, B.; Rakoczy, A.; Li, Y.

    2013-12-01

    Volatile organic chemicals (VOCs), such as chlorinated solvents and petroleum hydrocarbons, are prevalent groundwater contaminants due to their improper disposal and accidental spillage. In addition to contaminating groundwater, VOCs may partition into the overlying vadose zone and enter buildings through gaps and cracks in foundation slabs or basement walls, a process termed vapor intrusion. Vapor intrusion of VOCs has been recognized as a detrimental source for human exposures to potential carcinogenic or toxic compounds. The simulation of vapor intrusion from a subsurface source has been the focus of many studies to better understand the process and guide field investigation. While multiple analytical and numerical models were developed to simulate the vapor intrusion process, detailed validation of these models against well controlled experiments is still lacking, due to the complexity and uncertainties associated with site characterization and soil gas flux and indoor air concentration measurement. In this work, we present an effort to validate a three-dimensional vapor intrusion model based on a well-controlled experimental quantification of the vapor intrusion pathways into a slab-on-ground building under varying environmental conditions. Finally, a probabilistic approach based on Monte Carlo simulations is implemented to determine the probability distribution of indoor air concentration based on the most uncertain input parameters.

  13. Cost model validation: a technical and cultural approach

    NASA Technical Reports Server (NTRS)

    Hihn, J.; Rosenberg, L.; Roust, K.; Warfield, K.

    2001-01-01

    This paper summarizes how JPL's parametric mission cost model (PMCM) has been validated using both formal statistical methods and a variety of peer and management reviews in order to establish organizational acceptance of the cost model estimates.

  14. Translation, adaptation and validation of a Portuguese version of the Moorehead-Ardelt Quality of Life Questionnaire II.

    PubMed

    Maciel, João; Infante, Paulo; Ribeiro, Susana; Ferreira, André; Silva, Artur C; Caravana, Jorge; Carvalho, Manuel G

    2014-11-01

    The prevalence of obesity has increased worldwide. An assessment of the impact of obesity on health-related quality of life (HRQoL) requires specific instruments. The Moorehead-Ardelt Quality of Life Questionnaire II (MA-II) is a widely used instrument to assess HRQoL in morbidly obese patients. The objective of this study was to translate and validate a Portuguese version of the MA-II.The study included forward and backward translations of the original MA-II. The reliability of the Portuguese MA-II was estimated using the internal consistency and test-retest methods. For validation purposes, the Spearman's rank correlation coefficient was used to evaluate the correlation between the Portuguese MA-II and the Portuguese versions of two other questionnaires, the 36-item Short Form Health Survey (SF-36) and the Impact of Weight on Quality of Life-Lite (IWQOL-Lite).One hundred and fifty morbidly obese patients were randomly assigned to test the reliability and validity of the Portuguese MA-II. Good internal consistency was demonstrated by a Cronbach's alpha coefficient of 0.80, and a very good agreement in terms of test-retest reliability was recorded, with an overall intraclass correlation coefficient (ICC) of 0.88. The total sums of MA-II scores and each item of MA-II were significantly correlated with all domains of SF-36 and IWQOL-Lite. A statistically significant negative correlation was found between the MA-II total score and BMI. Moreover, age, gender and surgical status were independent predictors of MA-II total score.A reliable and valid Portuguese version of the MA-II was produced, thus enabling the routine use of MA-II in the morbidly obese Portuguese population. PMID:24817428

  15. ECOLOGICAL MODEL TESTING: VERIFICATION, VALIDATION OR NEITHER?

    EPA Science Inventory

    Consider the need to make a management decision about a declining animal population. Two models are available to help. Before a decision is made based on model results, the astute manager or policy maker may ask, "Do the models work?" Or, "Have the models been verified or validat...

  16. Parameterization of Model Validating Sets for Uncertainty Bound Optimizations. Revised

    NASA Technical Reports Server (NTRS)

    Lim, K. B.; Giesy, D. P.

    2000-01-01

    Given measurement data, a nominal model and a linear fractional transformation uncertainty structure with an allowance on unknown but bounded exogenous disturbances, easily computable tests for the existence of a model validating uncertainty set are given. Under mild conditions, these tests are necessary and sufficient for the case of complex, nonrepeated, block-diagonal structure. For the more general case which includes repeated and/or real scalar uncertainties, the tests are only necessary but become sufficient if a collinearity condition is also satisfied. With the satisfaction of these tests, it is shown that a parameterization of all model validating sets of plant models is possible. The new parameterization is used as a basis for a systematic way to construct or perform uncertainty tradeoff with model validating uncertainty sets which have specific linear fractional transformation structure for use in robust control design and analysis. An illustrative example which includes a comparison of candidate model validating sets is given.

  17. Using virtual reality to validate system models

    SciTech Connect

    Winter, V.L.; Caudell, T.P.

    1999-12-09

    To date most validation techniques are highly biased towards calculations involving symbolic representations of problems. These calculations are either formal (in the case of consistency and completeness checks), or informal in the case of code inspections. The authors believe that an essential type of evidence of the correctness of the formalization process must be provided by (i.e., must originate from) human-based calculation. They further believe that human calculation can by significantly amplified by shifting from symbolic representations to graphical representations. This paper describes their preliminary efforts in realizing such a representational shift.

  18. Validation of Numerical Shallow Water Models for Tidal Lagoons

    SciTech Connect

    Eliason, D.; Bourgeois, A.

    1999-11-01

    An analytical solution is presented for the case of a stratified, tidally forced lagoon. This solution, especially its energetics, is useful for the validation of numerical shallow water models under stratified, tidally forced conditions. The utility of the analytical solution for validation is demonstrated for a simple finite difference numerical model. A comparison is presented of the energetics of the numerical and analytical solutions in terms of the convergence of model results to the analytical solution with increasing spatial and temporal resolution.

  19. Validation of vehicle dynamics simulation models - a review

    NASA Astrophysics Data System (ADS)

    Kutluay, Emir; Winner, Hermann

    2014-02-01

    In this work, a literature survey on the validation of vehicle dynamics simulation models is presented. Estimating the dynamic responses of existing or proposed vehicles has a wide array of applications in the development of vehicle technologies, e.g. active suspensions, controller design, driver assistance systems, etc. Although simulation environments, measurement tools and mathematical theories on vehicle dynamics are well established, the methodical link between the experimental test data and validity analysis of the simulation model is still lacking. This report presents different views on the definition of validation, and its usage in vehicle dynamics simulation models.

  20. Adolescent Personality: A Five-Factor Model Construct Validation

    ERIC Educational Resources Information Center

    Baker, Spencer T.; Victor, James B.; Chambers, Anthony L.; Halverson, Jr., Charles F.

    2004-01-01

    The purpose of this study was to investigate convergent and discriminant validity of the five-factor model of adolescent personality in a school setting using three different raters (methods): self-ratings, peer ratings, and teacher ratings. The authors investigated validity through a multitrait-multimethod matrix and a confirmatory factor…

  1. Teacher Change Beliefs: Validating a Scale with Structural Equation Modelling

    ERIC Educational Resources Information Center

    Kin, Tai Mei; Abdull Kareem, Omar; Nordin, Mohamad Sahari; Wai Bing, Khuan

    2015-01-01

    The objectives of the study were to validate a substantiated Teacher Change Beliefs Model (TCBM) and an instrument to identify critical components of teacher change beliefs (TCB) in Malaysian secondary schools. Five different pilot test approaches were applied to ensure the validity and reliability of the instrument. A total of 936 teachers from…

  2. Validation of an Evaluation Model for Learning Management Systems

    ERIC Educational Resources Information Center

    Kim, S. W.; Lee, M. G.

    2008-01-01

    This study aims to validate a model for evaluating learning management systems (LMS) used in e-learning fields. A survey of 163 e-learning experts, regarding 81 validation items developed through literature review, was used to ascertain the importance of the criteria. A concise list of explanatory constructs, including two principle factors, was…

  3. Validation of a heteroscedastic hazards regression model.

    PubMed

    Wu, Hong-Dar Isaac; Hsieh, Fushing; Chen, Chen-Hsin

    2002-03-01

    A Cox-type regression model accommodating heteroscedasticity, with a power factor of the baseline cumulative hazard, is investigated for analyzing data with crossing hazards behavior. Since the approach of partial likelihood cannot eliminate the baseline hazard, an overidentified estimating equation (OEE) approach is introduced in the estimation procedure. It by-product, a model checking statistic, is presented to test for the overall adequacy of the heteroscedastic model. Further, under the heteroscedastic model setting, we propose two statistics to test the proportional hazards assumption. Implementation of this model is illustrated in a data analysis of a cancer clinical trial. PMID:11878222

  4. Line emission from H II blister models

    NASA Technical Reports Server (NTRS)

    Rubin, R. H.

    1984-01-01

    Numerical techniques to calculate the thermal and geometric properties of line emission from H II 'blister' regions are presented. It is assumed that the density distributions of the H II regions are a function of two dimensions, with rotational symmetry specifying the shape in three-dimensions. The thermal and ionization equilibrium equations of the problem are solved by spherical modeling, and a spherical sector approximation is used to simplify the three-dimensional treatment of diffuse ionizing radiation. The global properties of H II 'blister' regions near the edges of a molecular cloud are simulated by means of the geometry/density distribution, and the results are compared with observational data. It is shown that there is a monotonic increase of peak surface brightness from the i = 0 deg (pole-on) observational position to the i = 90 deg (edge-on) position. The enhancement of the line peak intensity from the edge-on to the pole-on positions is found to depend on the density, stratification, ionization, and electron temperature weighting. It is found that as i increases, the position of peak line brightness of the lower excitation species is displaced to the high-density side of the high excitation species.

  5. Validation of the Millon Clinical Multiaxial Inventory for Axis II disorders: does it meet the Daubert standard?

    PubMed

    Rogers, R; Salekin, R T; Sewell, K W

    1999-08-01

    Relevant to forensic practice, the Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) established the boundaries for the admissibility of scientific evidence that take into account its trustworthiness as assessed via evidentiary reliability. In conducting forensic evaluations, psychologists and other mental health professionals must be able to offer valid diagnoses, including Axis II disorders. The most widely available measure of personality disorders is the Million Clinical Multiaxial Inventory (MCMI) and its subsequent revisions (MCMI-II and MCMI-III). We address the critical question, "Do the MCMI-II and MCMI-III meet the requirements of Daubert?" Fundamental problems in the scientific validity and error rates for MCMI-III appear to preclude its admissibility under Daubert for the assessment of Axis II disorders. We address the construct validity for the MCMI and MCMI-II via a meta-analysis of 33 studies. The resulting multitrait-multimethod approach allowed us to address their convergent and discriminant validity through method effects (Marsh, 1990). With reference to Daubert, the results suggest a circumscribed use for the MCMI-II with good evidence of construct validity for Avoidant, Schizotypal, and Borderline personality disorders. PMID:10439726

  6. Psychometric validation of the BDI-II among HIV-positive CHARTER study participants.

    PubMed

    Hobkirk, Andréa L; Starosta, Amy J; De Leo, Joseph A; Marra, Christina M; Heaton, Robert K; Earleywine, Mitch

    2015-06-01

    Rates of depression are high among individuals living with HIV. Accurate assessment of depressive symptoms among this population is important for ensuring proper diagnosis and treatment. The Beck Depression Inventory-II (BDI-II) is a widely used measure for assessing depression, however its psychometric properties have not yet been investigated for use with HIV-positive populations in the United States. The current study was the first to assess the psychometric properties of the BDI-II among a large cohort of HIV-positive participants sampled at multiple sites across the United States as part of the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) study. The BDI-II test scores showed good internal consistency (α = .93) and adequate test-retest reliability (internal consistency coefficient = 0.83) over a 6-mo period. Using a "gold standard" of major depressive disorder determined by the Composite International Diagnostic Interview, sensitivity and specificity were maximized at a total cut-off score of 17 and a receiver operating characteristic analysis confirmed that the BDI-II is an adequate diagnostic measure for the sample (area under the curve = 0.83). The sensitivity and specificity of each score are provided graphically. Confirmatory factor analyses confirmed the best fit for a three-factor model over one-factor and two-factor models and models with a higher-order factor included. The results suggest that the BDI-II is an adequate measure for assessing depressive symptoms among U.S. HIV-positive patients. Cut-off scores should be adjusted to enhance sensitivity or specificity as needed and the measure can be differentiated into cognitive, affective, and somatic depressive symptoms. PMID:25419643

  7. Exploring the Validity of Valproic Acid Animal Model of Autism

    PubMed Central

    Mabunga, Darine Froy N.; Gonzales, Edson Luck T.; Kim, Ji-woon; Kim, Ki Chan

    2015-01-01

    The valproic acid (VPA) animal model of autism spectrum disorder (ASD) is one of the most widely used animal model in the field. Like any other disease models, it can't model the totality of the features seen in autism. Then, is it valid to model autism? This model demonstrates many of the structural and behavioral features that can be observed in individuals with autism. These similarities enable the model to define relevant pathways of developmental dysregulation resulting from environmental manipulation. The uncovering of these complex pathways resulted to the growing pool of potential therapeutic candidates addressing the core symptoms of ASD. Here, we summarize the validity points of VPA that may or may not qualify it as a valid animal model of ASD. PMID:26713077

  8. Economic analysis of model validation for a challenge problem

    DOE PAGESBeta

    Paez, Paul J.; Paez, Thomas L.; Hasselman, Timothy K.

    2016-02-19

    It is now commonplace for engineers to build mathematical models of the systems they are designing, building, or testing. And, it is nearly universally accepted that phenomenological models of physical systems must be validated prior to use for prediction in consequential scenarios. Yet, there are certain situations in which testing only or no testing and no modeling may be economically viable alternatives to modeling and its associated testing. This paper develops an economic framework within which benefit–cost can be evaluated for modeling and model validation relative to other options. The development is presented in terms of a challenge problem. Asmore » a result, we provide a numerical example that quantifies when modeling, calibration, and validation yield higher benefit–cost than a testing only or no modeling and no testing option.« less

  9. Exploring the Validity of Valproic Acid Animal Model of Autism.

    PubMed

    Mabunga, Darine Froy N; Gonzales, Edson Luck T; Kim, Ji-Woon; Kim, Ki Chan; Shin, Chan Young

    2015-12-01

    The valproic acid (VPA) animal model of autism spectrum disorder (ASD) is one of the most widely used animal model in the field. Like any other disease models, it can't model the totality of the features seen in autism. Then, is it valid to model autism? This model demonstrates many of the structural and behavioral features that can be observed in individuals with autism. These similarities enable the model to define relevant pathways of developmental dysregulation resulting from environmental manipulation. The uncovering of these complex pathways resulted to the growing pool of potential therapeutic candidates addressing the core symptoms of ASD. Here, we summarize the validity points of VPA that may or may not qualify it as a valid animal model of ASD. PMID:26713077

  10. Photon number conserving models of H II bubbles during reionization

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem; Choudhury, T. Roy; Padmanabhan, Hamsa

    2016-08-01

    Traditional excursion-set-based models of H II bubble growth during the epoch of reionization are known to violate photon number conservation, in the sense that the mass fraction in ionized bubbles in these models does not equal the ratio of the number of ionizing photons produced by sources and the number of hydrogen atoms in the intergalactic medium. E.g. for a Planck13 cosmology with electron scattering optical depth τ ≃ 0.066, the discrepancy is ˜15 per cent for x_{H II}=0.1 and ˜5 per cent for x_{H II}=0.5. We demonstrate that this problem arises from a fundamental conceptual shortcoming of the excursion-set approach (already recognized in the literature on this formalism) which only tracks average mass fractions instead of the exact, stochastic source counts. With this insight, we build an approximately photon number conserving Monte Carlo model of bubble growth based on partitioning regions of dark matter into haloes. Our model, which is formally valid for white noise initial conditions (ICs), shows dramatic improvements in photon number conservation, as well as substantial differences in the bubble size distribution, as compared to traditional models. We explore the trends obtained on applying our algorithm to more realistic ICs, finding that these improvements are robust to changes in the ICs. Since currently popular seminumerical schemes of bubble growth also violate photon number conservation, we argue that it will be worthwhile to pursue new, explicitly photon number conserving approaches. Along the way, we clarify some misconceptions regarding this problem that have appeared in the literature.

  11. Gear Windage Modeling Progress - Experimental Validation Status

    NASA Technical Reports Server (NTRS)

    Kunz, Rob; Handschuh, Robert F.

    2008-01-01

    In the Subsonics Rotary Wing (SRW) Project being funded for propulsion work at NASA Glenn Research Center, performance of the propulsion system is of high importance. In current rotorcraft drive systems many gearing components operate at high rotational speed (pitch line velocity > 24000 ft/ min). In our testing of high speed helical gear trains at NASA Glenn we have found that the work done on the air - oil mist within the gearbox can become a significant part of the power loss of the system. This loss mechanism is referred to as windage. The effort described in this presentation is to try to understand the variables that affect windage, develop a good experimental data base to validate, the analytical project being conducted at Penn State University by Dr. Rob Kunz under a NASA SRW NRA. The presentation provides an update to the status of these efforts.

  12. Measurements of Humidity in the Atmosphere and Validation Experiments (Mohave, Mohave II): Results Overview

    NASA Technical Reports Server (NTRS)

    Leblanc, Thierry; McDermid, Iain S.; McGee, Thomas G.; Twigg, Laurence W.; Sumnicht, Grant K.; Whiteman, David N.; Rush, Kurt D.; Cadirola, Martin P.; Venable, Demetrius D.; Connell, R.; Demoz, Belay B.; Vomel, Holger; Miloshevich, L.

    2008-01-01

    The Measurements of Humidity in the Atmosphere and Validation Experiments (MOHAVE, MOHAVE-II) inter-comparison campaigns took place at the Jet Propulsion Laboratory (JPL) Table Mountain Facility (TMF, 34.5(sup o)N) in October 2006 and 2007 respectively. Both campaigns aimed at evaluating the capability of three Raman lidars for the measurement of water vapor in the upper troposphere and lower stratosphere (UT/LS). During each campaign, more than 200 hours of lidar measurements were compared to balloon borne measurements obtained from 10 Cryogenic Frost-point Hygrometer (CFH) flights and over 50 Vaisala RS92 radiosonde flights. During MOHAVE, fluorescence in all three lidar receivers was identified, causing a significant wet bias above 10-12 km in the lidar profiles as compared to the CFH. All three lidars were reconfigured after MOHAVE, and no such bias was observed during the MOHAVE-II campaign. The lidar profiles agreed very well with the CFH up to 13-17 km altitude, where the lidar measurements become noise limited. The results from MOHAVE-II have shown that the water vapor Raman lidar will be an appropriate technique for the long-term monitoring of water vapor in the UT/LS given a slight increase in its power-aperture, as well as careful calibration.

  13. Reliability and validity of the modified Conconi test on concept II rowing ergometers.

    PubMed

    Celik, Ozgür; Koşar, Sükran Nazan; Korkusuz, Feza; Bozkurt, Murat

    2005-11-01

    The purpose of this study was to assess the reliability and validity of the modified Conconi test on Concept II rowing ergometers. Twenty-eight oarsmen conducted 3 performance tests on separate days. Reliability was assessed using the break point in heart rate (HR) linearity called the Conconi test (CT) and Conconi retest (CRT) for the noninvasive measurement of anaerobic threshold (AT). Blood lactate measurement was considered the gold standard for the assessment of the AT, and the validity of the CT was assessed by blood samples taken during an incremental load test (ILT) on ergometers. According to the results, the mean power output (PO) scores for the CT, CRT, and ILT were 234.2 +/- 40.3 W, 232.5 +/- 39.7 W, and 229.7 +/- 39.6 W, respectively. The mean HR values at the AT for the CT, CRT, and ILT were 165.4 +/- 11.2 b.min, 160.4 +/- 10.8 b.min, and 158.3 +/- 8.8 b.min, respectively. Interclass correlation coefficient (ICC) analysis indicated a significant correlation between the 3 tests with one another. Also, Bland and Altman plots showed that there was an association between noninvasive tests and the ILT PO scores and HRs (95% confidence interval [CI]). In conclusion, this study showed that the modified CT is a reliable and valid method for determining the AT of elite men rowers. PMID:16287355

  14. Validating the Mexican American Intergenerational Caregiving Model

    ERIC Educational Resources Information Center

    Escandon, Socorro

    2011-01-01

    The purpose of this study was to substantiate and further develop a previously formulated conceptual model of Role Acceptance in Mexican American family caregivers by exploring the theoretical strengths of the model. The sample consisted of women older than 21 years of age who self-identified as Hispanic, were related through consanguinal or…

  15. Ionospheric model validation at VLF and LF

    NASA Astrophysics Data System (ADS)

    Ferguson, Jerry A.

    1995-05-01

    A reliable knowledge of radio signal amplitude and phase characteristics is required to design and maintain communications and navigational circuits at VLF and LF. The ability to accurately calculate signal levels as a function of frequency, position, and time is of considerable importance in achieving reliable assessment of communication coverage. Detailed computer models based on multiple mode waveguide theory have been developed. These models have been found to produce good comparisons between measurements and calculations of signal variations as a function of propagation distance. However, results can be very sensitive to the ionospheric inputs to these computer models. This paper has two purposes. The first is to present the results of a systematic comparison of a set of measurements of signal strength from various transmitters over a number of propagation paths using a simple model of the ionosphere. The variation of the parameters of this simple model with basic propagation parameters is examined. The second purpose is to examine the built-in version of this simple model of the ionosphere as implemented in the Long Wave Propagation Capability. This model is found to adequately represent a set of in-flight signal strength measurements. It is also clear that there is still room for improvements in this ionospheric model.

  16. SWAT: Model use, calibration, and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    SWAT (Soil and Water Assessment Tool) is a comprehensive, semi-distributed river basin model that requires a large number of input parameters which complicates model parameterization and calibration. Several calibration techniques have been developed for SWAT including manual calibration procedures...

  17. Uncertainty Quantification and Validation for RANS Turbulence Models

    NASA Astrophysics Data System (ADS)

    Oliver, Todd; Moser, Robert

    2011-11-01

    Uncertainty quantification and validation procedures for RANS turbulence models are developed and applied. The procedures used here rely on a Bayesian view of probability. In particular, the uncertainty quantification methodology requires stochastic model development, model calibration, and model comparison, all of which are pursued using tools from Bayesian statistics. Model validation is also pursued in a probabilistic framework. The ideas and processes are demonstrated on a channel flow example. Specifically, a set of RANS models--including Baldwin-Lomax, Spalart-Allmaras, k- ɛ, k- ω, and v2- f--and uncertainty representations are analyzed using DNS data for fully-developed channel flow. Predictions of various quantities of interest and the validity (or invalidity) of the various models for making those predictions will be examined. This work is supported by the Department of Energy [National Nuclear Security Administration] under Award Number [DE-FC52-08NA28615].

  18. HEDR model validation plan. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Napier, B.A.; Gilbert, R.O.; Simpson, J.C.; Ramsdell, J.V. Jr.; Thiede, M.E.; Walters, W.H.

    1993-06-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project has developed a set of computational ``tools`` for estimating the possible radiation dose that individuals may have received from past Hanford Site operations. This document describes the planned activities to ``validate`` these tools. In the sense of the HEDR Project, ``validation`` is a process carried out by comparing computational model predictions with field observations and experimental measurements that are independent of those used to develop the model.

  19. Highlights of Transient Plume Impingement Model Validation and Applications

    NASA Technical Reports Server (NTRS)

    Woronowicz, Michael

    2011-01-01

    This paper describes highlights of an ongoing validation effort conducted to assess the viability of applying a set of analytic point source transient free molecule equations to model behavior ranging from molecular effusion to rocket plumes. The validation effort includes encouraging comparisons to both steady and transient studies involving experimental data and direct simulation Monte Carlo results. Finally, this model is applied to describe features of two exotic transient scenarios involving NASA Goddard Space Flight Center satellite programs.

  20. VERIFICATION AND VALIDATION OF THE SPARC MODEL

    EPA Science Inventory

    Mathematical models for predicting the transport and fate of pollutants in the environment require reactivity parameter values--that is, the physical and chemical constants that govern reactivity. Although empirical structure-activity relationships that allow estimation of some ...

  1. Validation of geometric models for fisheye lenses

    NASA Astrophysics Data System (ADS)

    Schneider, D.; Schwalbe, E.; Maas, H.-G.

    The paper focuses on the photogrammetric investigation of geometric models for different types of optical fisheye constructions (equidistant, equisolid-angle, sterographic and orthographic projection). These models were implemented and thoroughly tested in a spatial resection and a self-calibrating bundle adjustment. For this purpose, fisheye images were taken with a Nikkor 8 mm fisheye lens on a Kodak DSC 14n Pro digital camera in a hemispherical calibration room. Both, the spatial resection and the bundle adjustment resulted in a standard deviation of unit weight of 1/10 pixel with a suitable set of simultaneous calibration parameters introduced into the camera model. The camera-lens combination was treated with all of the four basic models mentioned above. Using the same set of additional lens distortion parameters, the differences between the models can largely be compensated, delivering almost the same precision parameters. The relative object space precision obtained from the bundle adjustment was ca. 1:10 000 of the object dimensions. This value can be considered as a very satisfying result, as fisheye images generally have a lower geometric resolution as a consequence of their large field of view and also have a inferior imaging quality in comparison to most central perspective lenses.

  2. Validation of Model Forecasts of the Ambient Solar Wind

    NASA Technical Reports Server (NTRS)

    Macneice, P. J.; Hesse, M.; Kuznetsova, M. M.; Rastaetter, L.; Taktakishvili, A.

    2009-01-01

    Independent and automated validation is a vital step in the progression of models from the research community into operational forecasting use. In this paper we describe a program in development at the CCMC to provide just such a comprehensive validation for models of the ambient solar wind in the inner heliosphere. We have built upon previous efforts published in the community, sharpened their definitions, and completed a baseline study. We also provide first results from this program of the comparative performance of the MHD models available at the CCMC against that of the Wang-Sheeley-Arge (WSA) model. An important goal of this effort is to provide a consistent validation to all available models. Clearly exposing the relative strengths and weaknesses of the different models will enable forecasters to craft more reliable ensemble forecasting strategies. Models of the ambient solar wind are developing rapidly as a result of improvements in data supply, numerical techniques, and computing resources. It is anticipated that in the next five to ten years, the MHD based models will supplant semi-empirical potential based models such as the WSA model, as the best available forecast models. We anticipate that this validation effort will track this evolution and so assist policy makers in gauging the value of past and future investment in modeling support.

  3. Validation of Model Forecasts of the Ambient Solar Wind (Invited)

    NASA Astrophysics Data System (ADS)

    MacNeice, P. J.; Hesse, M.; Kuznetsova, M. M.; Rastaetter, L.; Taktakishvili, A.

    2009-12-01

    Independent and automated validation is a vital step in the progression of models from the research community into operational forecasting use. In this paper we describe a program in development at the CCMC to provide just such a comprehensive validation for models of the ambient solar wind in the inner heliosphere. We have built upon previous efforts published in the community, sharpened their definitions, and completed a baseline study. We also provide first results from this program of the comparative performance of the MHD models available at the CCMC against that of the Wang-Sheeley-Arge(WSA) model. An important goal of this effort is to provide a consistent validation to all available models. Clearly exposing the relative strengths and weaknesses of the different models will enable forecasters to craft more reliable ensemble forecasting strategies. Models of the ambient solar wind are developing rapidly as a result of improvements in data supply, numerical techniques, and computing resources. It is anticipated that in the next five to ten years, the MHD based models will supplant semi-empirical potential based models such as the WSA model, as the best available forecast models. We anticipate that this validation effort will track this evolution and so assist policy makers in gauging the value of past and future investment in modeling support.

  4. Shuttle Spacesuit: Fabric/LCVG Model Validation

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Tweed, J.; Zeitlin, C.; Kim, M.-H. Y.; Anderson, B. M.; Cucinotta, F. A.; Ware, J.; Persans, A. E.

    2001-01-01

    A detailed spacesuit computational model is being developed at the Langley Research Center for radiation exposure evaluation studies. The details of the construction of the spacesuit are critical to estimation of exposures and assessing the risk to the astronaut on EVA. Past evaluations of spacesuit shielding properties assumed the basic fabric lay-up (Thermal Micrometeroid Garment, fabric restraints, and pressure envelope) and Liquid Cooling and Ventilation Garment (LCVG) could be homogenized as a single layer overestimating the protective properties over 60 percent of the fabric area. The present spacesuit model represents the inhomogeneous distributions of LCVG materials (mainly the water filled cooling tubes). An experimental test is performed using a 34-MeV proton beam and highresolution detectors to compare with model-predicted transmission factors. Some suggestions are made on possible improved construction methods to improve the spacesuit's protection properties.

  5. Shuttle Spacesuit: Fabric/LCVG Model Validation

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Tweed, J.; Zeitflin, C.; Kim, M.-H.; Anderson, B. M.; Cucinotta, F. A.; Ware, J.; Persans, A. E.

    2001-01-01

    A detailed spacesuit computational model is being developed at the Langley Research Center for radiation exposure evaluation studies. The details of the construction of the spacesuit are critical to estimation of exposures and assessing the risk to the astronaut on EVA. Past evaluations of spacesuit shielding properties assumed the basic fabric lay-up (Thermal Micrometeroid Garment, fabric restraints, and pressure envelope) and Liquid Cooling and Ventilation Garment (LCVG) could be homogenized as a single layer overestimating the protective properties over 60 percent of the fabric area. The present spacesuit model represents the inhomogeneous distributions of LCVG materials (mainly the water filled cooling tubes). An experimental test is performed using a 34-MeV proton beam and high- resolution detectors to compare with model-predicted transmission factors. Some suggestions are made on possible improved construction methods to improve the spacesuit's protection properties.

  6. Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II; Validation

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Loukachine, K.; Wielicki, B. A.; Young, D. F.

    2003-01-01

    Top-of-atmosphere (TOA) radiative fluxes from the Clouds and the Earth s Radiant Energy System (CERES) are estimated from empirical angular distribution models (ADMs) that convert instantaneous radiance measurements to TOA fluxes. This paper evaluates the accuracy of CERES TOA fluxes obtained from a new set of ADMs developed for the CERES instrument onboard the Tropical Rainfall Measuring Mission (TRMM). The uncertainty in regional monthly mean reflected shortwave (SW) and emitted longwave (LW) TOA fluxes is less than 0.5 W/sq m, based on comparisons with TOA fluxes evaluated by direct integration of the measured radiances. When stratified by viewing geometry, TOA fluxes from different angles are consistent to within 2% in the SW and 0.7% (or 2 W/sq m) in the LW. In contrast, TOA fluxes based on ADMs from the Earth Radiation Budget Experiment (ERBE) applied to the same CERES radiance measurements show a 10% relative increase with viewing zenith angle in the SW and a 3.5% (9 W/sq m) decrease with viewing zenith angle in the LW. Based on multiangle CERES radiance measurements, 18 regional instantaneous TOA flux errors from the new CERES ADMs are estimated to be 10 W/sq m in the SW and, 3.5 W/sq m in the LW. The errors show little or no dependence on cloud phase, cloud optical depth, and cloud infrared emissivity. An analysis of cloud radiative forcing (CRF) sensitivity to differences between ERBE and CERES TRMM ADMs, scene identification, and directional models of albedo as a function of solar zenith angle shows that ADM and clear-sky scene identification differences can lead to an 8 W/sq m root-mean-square (rms) difference in 18 daily mean SW CRF and a 4 W/sq m rms difference in LW CRF. In contrast, monthly mean SW and LW CRF differences reach 3 W/sq m. CRF is found to be relatively insensitive to differences between the ERBE and CERES TRMM directional models.

  7. Validation of the NATO-standard ship signature model (SHIPIR)

    NASA Astrophysics Data System (ADS)

    Vaitekunas, David A.; Fraedrich, Douglas S.

    1999-07-01

    An integrated naval infrared target, threat and countermeasure simulator (SHIPIR/NTCS) has been developed. The SHIPIR component of the model has been adopted by both NATO and the US Navy as a common tool for predicting the infrared (IR) signature of naval ships in their background. The US Navy has taken a lead role in further developing and validating SHIPIR for use in the Twenty-First Century Destroyer (DD-21) program. As a result, the US Naval Research Laboratory (NRL) has performed an in-depth validation of SHIPIR. This paper presents an overview of SHIPIR, the model validation methodology developed by NRL, and the results of the NRL validation study. The validation consists of three parts: a review of existing validation information, the design, execution, and analysis of a new panel test experiment, and the comparison of experiment with predictions from the latest version of SHIPIR (v2.5). The results show high levels of accuracy in the radiometric components of the model under clear-sky conditions, but indicate the need for more detailed measurement of solar irradiance and cloud model data for input to the heat transfer and in-band sky radiance sub-models, respectively.

  8. WEPP: Model use, calibration and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Water Erosion Prediction Project (WEPP) model is a process-based, continuous simulation, distributed parameter, hydrologic and soil erosion prediction system. It has been developed over the past 25 years to allow for easy application to a large number of land management scenarios. Most general o...

  9. Distance Education in Taiwan: A Model Validated.

    ERIC Educational Resources Information Center

    Shih, Mei-Yau; Zvacek, Susan M.

    The Triad Perspective Model of Distance Education (TPMDE) guides researchers in developing research questions, gathering data, and producing a comprehensive description of a distance education program. It was developed around three theoretical perspectives: (1) curriculum development theory (Tyler's four questions, 1949); (2) systems theory…

  10. WEPP: Model use, calibration, and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Water Erosion Prediction Project (WEPP) model is a process-based, continuous simulation, distributed parameter, hydrologic and soil erosion prediction system. It has been developed over the past 25 years to allow for easy application to a large number of land management scenarios. Most general o...

  11. Theory and Implementation of Nuclear Safety System Codes - Part II: System Code Closure Relations, Validation, and Limitations

    SciTech Connect

    Glenn A Roth; Fatih Aydogan

    2014-09-01

    This is Part II of two articles describing the details of thermal-hydraulic sys- tem codes. In this second part of the article series, the system code closure relationships (used to model thermal and mechanical non-equilibrium and the coupling of the phases) for the governing equations are discussed and evaluated. These include several thermal and hydraulic models, such as heat transfer coefficients for various flow regimes, two phase pressure correlations, two phase friction correlations, drag coefficients and interfacial models be- tween the fields. These models are often developed from experimental data. The experiment conditions should be understood to evaluate the efficacy of the closure models. Code verification and validation, including Separate Effects Tests (SETs) and Integral effects tests (IETs) is also assessed. It can be shown from the assessments that the test cases cover a significant section of the system code capabilities, but some of the more advanced reactor designs will push the limits of validation for the codes. Lastly, the limitations of the codes are discussed by considering next generation power plants, such as Small Modular Reactors (SMRs), analyz- ing not only existing nuclear power plants, but also next generation nuclear power plants. The nuclear industry is developing new, innovative reactor designs, such as Small Modular Reactors (SMRs), High-Temperature Gas-cooled Reactors (HTGRs) and others. Sub-types of these reactor designs utilize pebbles, prismatic graphite moderators, helical steam generators, in- novative fuel types, and many other design features that may not be fully analyzed by current system codes. This second part completes the series on the comparison and evaluation of the selected reactor system codes by discussing the closure relations, val- idation and limitations. These two articles indicate areas where the models can be improved to adequately address issues with new reactor design and development.

  12. Validation of the Poisson Stochastic Radiative Transfer Model

    NASA Technical Reports Server (NTRS)

    Zhuravleva, Tatiana; Marshak, Alexander

    2004-01-01

    A new approach to validation of the Poisson stochastic radiative transfer method is proposed. In contrast to other validations of stochastic models, the main parameter of the Poisson model responsible for cloud geometrical structure - cloud aspect ratio - is determined entirely by matching measurements and calculations of the direct solar radiation. If the measurements of the direct solar radiation is unavailable, it was shown that there is a range of the aspect ratios that allows the stochastic model to accurately approximate the average measurements of surface downward and cloud top upward fluxes. Realizations of the fractionally integrated cascade model are taken as a prototype of real measurements.

  13. Experiments for foam model development and validation.

    SciTech Connect

    Bourdon, Christopher Jay; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Mahoney, James F.; Russick, Edward Mark; Adolf, Douglas Brian; Rao, Rekha Ranjana; Thompson, Kyle Richard; Kraynik, Andrew Michael; Castaneda, Jaime N.; Brotherton, Christopher M.; Mondy, Lisa Ann; Gorby, Allen D.

    2008-09-01

    A series of experiments has been performed to allow observation of the foaming process and the collection of temperature, rise rate, and microstructural data. Microfocus video is used in conjunction with particle image velocimetry (PIV) to elucidate the boundary condition at the wall. Rheology, reaction kinetics and density measurements complement the flow visualization. X-ray computed tomography (CT) is used to examine the cured foams to determine density gradients. These data provide input to a continuum level finite element model of the blowing process.

  14. Field Validation of the Career Education Curriculum Project Modules. Phase II. K-6 Validation. Final Report. Part I.

    ERIC Educational Resources Information Center

    Moore, Earl; Wellman, Frank

    Field validation of the Missouri Career Education Curriculum Project Modules, K-6, was conducted in two phases. In phase 1, three sets of evaluation instruments were produced: K-1, 2-3, and 4-6. In phase 2, the field validation of the K-6 modules was conducted (reported here). (An additional goal of phase 2 was to develop evaluation instruments…

  15. Validating Requirements for Fault Tolerant Systems Using Model Checking

    NASA Technical Reports Server (NTRS)

    Schneider, Francis; Easterbrook, Steve M.; Callahan, John R.; Holzmann, Gerard J.

    1997-01-01

    Model checking is shown to be an effective tool in validating the behavior of a fault tolerant embedded spacecraft controller. The case study presented here shows that by judiciously abstracting away extraneous complexity, the state space of the model could be exhaustively searched allowing critical functional requirements to be validated down to the design level. Abstracting away detail not germane to the problem of interest leaves by definition a partial specification behind. The success of this procedure shows that it is feasible to effectively validate a partial specification with this technique. Three anomalies were found in the system one of which is an error in the detailed requirements, and the other two are missing/ambiguous requirements. Because the method allows validation of partial specifications, it also is an effective methodology towards maintaining fidelity between a co-evolving specification and an implementation.

  16. Analysis of Experimental Data for High Burnup PWR Spent Fuel Isotopic Validation - Vandellos II Reactor

    SciTech Connect

    Ilas, Germina; Gauld, Ian C

    2011-01-01

    This report is one of the several recent NUREG/CR reports documenting benchmark-quality radiochemical assay data and the use of the data to validate computer code predictions of isotopic composition for spent nuclear fuel, to establish the uncertainty and bias associated with code predictions. The experimental data analyzed in the current report were acquired from a high-burnup fuel program coordinated by Spanish organizations. The measurements included extensive actinide and fission product data of importance to spent fuel safety applications, including burnup credit, decay heat, and radiation source terms. Six unique spent fuel samples from three uranium oxide fuel rods were analyzed. The fuel rods had a 4.5 wt % {sup 235}U initial enrichment and were irradiated in the Vandellos II pressurized water reactor operated in Spain. The burnups of the fuel samples range from 42 to 78 GWd/MTU. The measurements were used to validate the two-dimensional depletion sequence TRITON in the SCALE computer code system.

  17. Systematic review and validation of prognostic models in liver transplantation.

    PubMed

    Jacob, Matthew; Lewsey, James D; Sharpin, Carlos; Gimson, Alexander; Rela, Mohammed; van der Meulen, Jan H P

    2005-07-01

    A model that can accurately predict post-liver transplant mortality would be useful for clinical decision making, would help to provide patients with prognostic information, and would facilitate fair comparisons of surgical performance between transplant units. A systematic review of the literature was carried out to assess the quality of the studies that developed and validated prognostic models for mortality after liver transplantation and to validate existing models in a large data set of patients transplanted in the United Kingdom (UK) and Ireland between March 1994 and September 2003. Five prognostic model papers were identified. The quality of the development and validation of all prognostic models was suboptimal according to an explicit assessment tool of the internal, external, and statistical validity, model evaluation, and practicality. The discriminatory ability of the identified models in the UK and Ireland data set was poor (area under the receiver operating characteristic curve always smaller than 0.7 for adult populations). Due to the poor quality of the reporting, the methodology used for the development of the model could not always be determined. In conclusion, these findings demonstrate that currently available prognostic models of mortality after liver transplantation can have only a limited role in clinical practice, audit, and research. PMID:15973726

  18. Model-Based Verification and Validation of Spacecraft Avionics

    NASA Technical Reports Server (NTRS)

    Khan, M. Omair; Sievers, Michael; Standley, Shaun

    2012-01-01

    Verification and Validation (V&V) at JPL is traditionally performed on flight or flight-like hardware running flight software. For some time, the complexity of avionics has increased exponentially while the time allocated for system integration and associated V&V testing has remained fixed. There is an increasing need to perform comprehensive system level V&V using modeling and simulation, and to use scarce hardware testing time to validate models; the norm for thermal and structural V&V for some time. Our approach extends model-based V&V to electronics and software through functional and structural models implemented in SysML. We develop component models of electronics and software that are validated by comparison with test results from actual equipment. The models are then simulated enabling a more complete set of test cases than possible on flight hardware. SysML simulations provide access and control of internal nodes that may not be available in physical systems. This is particularly helpful in testing fault protection behaviors when injecting faults is either not possible or potentially damaging to the hardware. We can also model both hardware and software behaviors in SysML, which allows us to simulate hardware and software interactions. With an integrated model and simulation capability we can evaluate the hardware and software interactions and identify problems sooner. The primary missing piece is validating SysML model correctness against hardware; this experiment demonstrated such an approach is possible.

  19. Validation of Orthorectified Interferometric Radar Imagery and Digital Elevation Models

    NASA Technical Reports Server (NTRS)

    Smith Charles M.

    2004-01-01

    This work was performed under NASA's Verification and Validation (V&V) Program as an independent check of data supplied by EarthWatch, Incorporated, through the Earth Science Enterprise Scientific Data Purchase (SDP) Program. This document serves as the basis of reporting results associated with validation of orthorectified interferometric interferometric radar imagery and digital elevation models (DEM). This validation covers all datasets provided under the first campaign (Central America & Virginia Beach) plus three earlier missions (Indonesia, Red River: and Denver) for a total of 13 missions.

  20. Validation of the Serpent 2 code on TRIGA Mark II benchmark experiments.

    PubMed

    Ćalić, Dušan; Žerovnik, Gašper; Trkov, Andrej; Snoj, Luka

    2016-01-01

    The main aim of this paper is the development and validation of a 3D computational model of TRIGA research reactor using Serpent 2 code. The calculated parameters were compared to the experimental results and to calculations performed with the MCNP code. The results show that the calculated normalized reaction rates and flux distribution within the core are in good agreement with MCNP and experiment, while in the reflector the flux distribution differ up to 3% from the measurements. PMID:26516989

  1. Functional state modelling approach validation for yeast and bacteria cultivations

    PubMed Central

    Roeva, Olympia; Pencheva, Tania

    2014-01-01

    In this paper, the functional state modelling approach is validated for modelling of the cultivation of two different microorganisms: yeast (Saccharomyces cerevisiae) and bacteria (Escherichia coli). Based on the available experimental data for these fed-batch cultivation processes, three different functional states are distinguished, namely primary product synthesis state, mixed oxidative state and secondary product synthesis state. Parameter identification procedures for different local models are performed using genetic algorithms. The simulation results show high degree of adequacy of the models describing these functional states for both S. cerevisiae and E. coli cultivations. Thus, the local models are validated for the cultivation of both microorganisms. This fact is a strong structure model verification of the functional state modelling theory not only for a set of yeast cultivations, but also for bacteria cultivation. As such, the obtained results demonstrate the efficiency and efficacy of the functional state modelling approach. PMID:26740778

  2. Dynamic Model Validation with Governor Deadband on the Eastern Interconnection

    SciTech Connect

    Kou, Gefei; Hadley, Stanton W; Liu, Yilu

    2014-04-01

    This report documents the efforts to perform dynamic model validation on the Eastern Interconnection (EI) by modeling governor deadband. An on-peak EI dynamic model is modified to represent governor deadband characteristics. Simulation results are compared with synchrophasor measurements collected by the Frequency Monitoring Network (FNET/GridEye). The comparison shows that by modeling governor deadband the simulated frequency response can closely align with the actual system response.

  3. Validation of a terrestrial food chain model

    SciTech Connect

    Travis, C.C.; Blaylock, B.P. )

    1992-04-01

    An increasingly important topic in risk assessment is the estimation of human exposure to environmental pollutants through pathways other than inhalation. The Environmental Protection Agency (EPA) has recently developed a computerized methodology (EPA, 1990) to estimate indirect exposure to toxic pollutants from Municipal Waste Combuster emissions. This methodology estimates health risks from exposure to toxic pollutants from the terrestrial food chain (TFC), soil ingestion, drinking water ingestion, fish ingestion, and dermal absorption via soil and water. Of these, one of the most difficult to estimate is exposure through the food chain. This paper estimates the accuracy of the EPA methodology for estimating food chain contamination. To our knowledge, no data exist on measured concentrations of pollutants in food grown around Municipal Waste Incinerators, and few field-scale studies have been performed on the uptake of pollutants in the food chain. Therefore, to evaluate the EPA methodology, we compare actual measurements of background contaminant levels in food with estimates made using EPA's computerized methodology. Background levels of contaminants in air, water, and soil were used as input to the EPA food chain model to predict background levels of contaminants in food. These predicted values were then compared with the measured background contaminant levels. Comparisons were performed for dioxin, pentachlorophenol, polychlorinated biphenyls, benzene, benzo(a)pyrene, mercury, and lead.

  4. Validating Physics-based Space Weather Models for Operational Use

    NASA Astrophysics Data System (ADS)

    Gombosi, Tamas; Singer, Howard; Millward, George; Toth, Gabor; Welling, Daniel

    2016-07-01

    The Geospace components of the Space Weather Modeling Framework developed at the University of Michigan is presently transitioned to operational use by the NOAA Space Weather Prediction Center. This talk will discuss the various ways the model is validated and skill scores are calculated.

  5. Validation of 1-D transport and sawtooth models for ITER

    SciTech Connect

    Connor, J.W.; Turner, M.F.; Attenberger, S.E.; Houlberg, W.A.

    1996-12-31

    In this paper the authors describe progress on validating a number of local transport models by comparing their predictions with relevant experimental data from a range of tokamaks in the ITER profile database. This database, the testing procedure and results are discussed. In addition a model for sawtooth oscillations is used to investigate their effect in an ITER plasma with alpha-particles.

  6. Validation of a metabolic cotton seedling emergence model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A seedling emergence model based on thermal dependence of enzyme activity in germinating cotton was developed. The model was validated under both laboratory and field conditions with several cotton lines under diverse temperature regimes. Four commercial lines were planted on four dates in Lubbock T...

  7. Validating regional-scale surface energy balance models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the major challenges in developing reliable regional surface flux models is the relative paucity of scale-appropriate validation data. Direct comparisons between coarse-resolution model flux estimates and flux tower data can often be dominated by sub-pixel heterogeneity effects, making it di...

  8. Validating a Technology Enhanced Student-Centered Learning Model

    ERIC Educational Resources Information Center

    Kang, Myunghee; Hahn, Jungsun; Chung, Warren

    2015-01-01

    The Technology Enhanced Student Centered Learning (TESCL) Model in this study presents the core factors that ensure the quality of learning in a technology-supported environment. Although the model was conceptually constructed using a student-centered learning framework and drawing upon previous studies, it should be validated through real-world…

  9. A Formal Approach to Empirical Dynamic Model Optimization and Validation

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G; Morelli, Eugene A.; Kenny, Sean P.; Giesy, Daniel P.

    2014-01-01

    A framework was developed for the optimization and validation of empirical dynamic models subject to an arbitrary set of validation criteria. The validation requirements imposed upon the model, which may involve several sets of input-output data and arbitrary specifications in time and frequency domains, are used to determine if model predictions are within admissible error limits. The parameters of the empirical model are estimated by finding the parameter realization for which the smallest of the margins of requirement compliance is as large as possible. The uncertainty in the value of this estimate is characterized by studying the set of model parameters yielding predictions that comply with all the requirements. Strategies are presented for bounding this set, studying its dependence on admissible prediction error set by the analyst, and evaluating the sensitivity of the model predictions to parameter variations. This information is instrumental in characterizing uncertainty models used for evaluating the dynamic model at operating conditions differing from those used for its identification and validation. A practical example based on the short period dynamics of the F-16 is used for illustration.

  10. Predicting the ungauged basin: Model validation and realism assessment

    NASA Astrophysics Data System (ADS)

    van Emmerik, Tim; Mulder, Gert; Eilander, Dirk; Piet, Marijn; Savenije, Hubert

    2015-10-01

    The hydrological decade on Predictions in Ungauged Basins (PUB) led to many new insights in model development, calibration strategies, data acquisition and uncertainty analysis. Due to a limited amount of published studies on genuinely ungauged basins, model validation and realism assessment of model outcome has not been discussed to a great extent. With this paper we aim to contribute to the discussion on how one can determine the value and validity of a hydrological model developed for an ungauged basin. As in many cases no local, or even regional, data are available, alternative methods should be applied. Using a PUB case study in a genuinely ungauged basin in southern Cambodia, we give several examples of how one can use different types of soft data to improve model design, calibrate and validate the model, and assess the realism of the model output. A rainfall-runoff model was coupled to an irrigation reservoir, allowing the use of additional and unconventional data. The model was mainly forced with remote sensing data, and local knowledge was used to constrain the parameters. Model realism assessment was done using data from surveys. This resulted in a successful reconstruction of the reservoir dynamics, and revealed the different hydrological characteristics of the two topographical classes. This paper does not present a generic approach that can be transferred to other ungauged catchments, but it aims to show how clever model design and alternative data acquisition can result in a valuable hydrological model for an ungauged catchment.

  11. A model for the separation of cloud and aerosol in SAGE II occultation data

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Winker, D. M.; Osborn, M. T.; Skeens, K. M.

    1993-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) II satellite experiment measures the extinction due to aerosols and thin cloud, at wavelengths of 0.525 and 1.02 micrometers, down to an altitude of 6 km. The wavelength dependence of the extinction due to aerosols differs from that of the extinction due to cloud and is used as the basis of a model for separating these two components. The model is presented and its validation using airborne lidar data, obtained coincident with SAGE II observations, is described. This comparison shows that smaller SAGE II cloud extinction values correspond to the presence of subvisible cirrus cloud in the lidar record. Examples of aerosol and cloud data products obtained using this model to interpret SAGE II upper tropospheric and lower stratospheric data are also shown.

  12. Control Oriented Modeling and Validation of Aeroservoelastic Systems

    NASA Technical Reports Server (NTRS)

    Crowder, Marianne; deCallafon, Raymond (Principal Investigator)

    2002-01-01

    Lightweight aircraft design emphasizes the reduction of structural weight to maximize aircraft efficiency and agility at the cost of increasing the likelihood of structural dynamic instabilities. To ensure flight safety, extensive flight testing and active structural servo control strategies are required to explore and expand the boundary of the flight envelope. Aeroservoelastic (ASE) models can provide online flight monitoring of dynamic instabilities to reduce flight time testing and increase flight safety. The success of ASE models is determined by the ability to take into account varying flight conditions and the possibility to perform flight monitoring under the presence of active structural servo control strategies. In this continued study, these aspects are addressed by developing specific methodologies and algorithms for control relevant robust identification and model validation of aeroservoelastic structures. The closed-loop model robust identification and model validation are based on a fractional model approach where the model uncertainties are characterized in a closed-loop relevant way.

  13. A prediction model for ocular damage - Experimental validation.

    PubMed

    Heussner, Nico; Vagos, Márcia; Spitzer, Martin S; Stork, Wilhelm

    2015-08-01

    With the increasing number of laser applications in medicine and technology, accidental as well as intentional exposure of the human eye to laser sources has become a major concern. Therefore, a prediction model for ocular damage (PMOD) is presented within this work and validated for long-term exposure. This model is a combination of a raytracing model with a thermodynamical model of the human and an application which determines the thermal damage by the implementation of the Arrhenius integral. The model is based on our earlier work and is here validated against temperature measurements taken with porcine eye samples. For this validation, three different powers were used: 50mW, 100mW and 200mW with a spot size of 1.9mm. Also, the measurements were taken with two different sensing systems, an infrared camera and a fibre optic probe placed within the tissue. The temperatures were measured up to 60s and then compared against simulations. The measured temperatures were found to be in good agreement with the values predicted by the PMOD-model. To our best knowledge, this is the first model which is validated for both short-term and long-term irradiations in terms of temperature and thus demonstrates that temperatures can be accurately predicted within the thermal damage regime. PMID:26267496

  14. Pharmacophore modeling studies of type I and type II kinase inhibitors of Tie2.

    PubMed

    Xie, Qing-Qing; Xie, Huan-Zhang; Ren, Ji-Xia; Li, Lin-Li; Yang, Sheng-Yong

    2009-02-01

    In this study, chemical feature based pharmacophore models of type I and type II kinase inhibitors of Tie2 have been developed with the aid of HipHop and HypoRefine modules within Catalyst program package. The best HipHop pharmacophore model Hypo1_I for type I kinase inhibitors contains one hydrogen-bond acceptor, one hydrogen-bond donor, one general hydrophobic, one hydrophobic aromatic, and one ring aromatic feature. And the best HypoRefine model Hypo1_II for type II kinase inhibitors, which was characterized by the best correlation coefficient (0.976032) and the lowest RMSD (0.74204), consists of two hydrogen-bond donors, one hydrophobic aromatic, and two general hydrophobic features, as well as two excluded volumes. These pharmacophore models have been validated by using either or both test set and cross validation methods, which shows that both the Hypo1_I and Hypo1_II have a good predictive ability. The space arrangements of the pharmacophore features in Hypo1_II are consistent with the locations of the three portions making up a typical type II kinase inhibitor, namely, the portion occupying the ATP binding region (ATP-binding-region portion, AP), that occupying the hydrophobic region (hydrophobic-region portion, HP), and that linking AP and HP (bridge portion, BP). Our study also reveals that the ATP-binding-region portion of the type II kinase inhibitors plays an important role to the bioactivity of the type II kinase inhibitors. Structural modifications on this portion should be helpful to further improve the inhibitory potency of type II kinase inhibitors. PMID:19138543

  15. The Validation of Climate Models: The Development of Essential Practice

    NASA Astrophysics Data System (ADS)

    Rood, R. B.

    2011-12-01

    It is possible from both a scientific and philosophical perspective to state that climate models cannot be validated. However, with the realization that the scientific investigation of climate change is as much a subject of politics as of science, maintaining this formal notion of "validation" has significant consequences. For example, it relegates the bulk of work of many climate scientists to an exercise of model evaluation that can be construed as ill-posed. Even within the science community this motivates criticism of climate modeling as an exercise of weak scientific practice. Stepping outside of the science community, statements that validation is impossible are used in political arguments to discredit the scientific investigation of climate, to maintain doubt about projections of climate change, and hence, to prohibit the development of public policy to regulate the emissions of greenhouse gases. With the acceptance of the impossibility of validation, scientists often state that the credibility of models can be established through an evaluation process. A robust evaluation process leads to the quantitative description of the modeling system against a standard set of measures. If this process is standardized as institutional practice, then this provides a measure of model performance from one modeling release to the next. It is argued, here, that such a robust and standardized evaluation of climate models can be structured and quantified as "validation." Arguments about the nuanced meaning of validation and evaluation are a subject about which the climate modeling community needs to develop a standard. It does injustice to a body of science-based knowledge to maintain that validation is "impossible." Rather than following such a premise, which immediately devalues the knowledge base, it is more useful to develop a systematic, standardized approach to robust, appropriate validation. This stands to represent the complexity of the Earth's climate and its

  16. Modeling Topaz-II system performance

    SciTech Connect

    Lee, H.H.; Klein, A.C. )

    1993-01-01

    The US acquisition of the Topaz-11 in-core thermionic space reactor test system from Russia provides a good opportunity to perform a comparison of the Russian reported data and the results from computer codes such as MCNP (Ref. 3) and TFEHX (Ref. 4). The comparison study includes both neutronic and thermionic performance analyses. The Topaz II thermionic reactor is modeled with MCNP using actual Russian dimensions and parameters. The computation of the neutronic performance considers several important aspects such as the fuel enrichment and location of the thermionic fuel elements (TFES) in the reactor core. The neutronic analysis included the calculation of both radial and axial power distribution, which are then used in the TFEHX code for electrical performance. The reactor modeled consists of 37 single-cell TFEs distributed in a 13-cm-radius zirconium hydride block surrounded by 8 cm of beryllium metal reflector. The TFEs use 90% enriched [sup 235]U and molybdenum coated with a thin layer of [sup 184]W for emitter surface. Electrons emitted are captured by a collector surface with a gap filled with cesium vapor between the collector and emitter surfaces. The collector surface is electrically insulated with alumina. Liquid NaK provides the cooling system for the TFEs. The axial thermal power distribution is obtained by dividing the TFE into 40 axial nodes. Comparison of the true axial power distribution with that produced by electrical heaters was also performed.

  17. Analysis of the absorptive behavior of photopolymer materials. Part II. Experimental validation

    NASA Astrophysics Data System (ADS)

    Li, Haoyu; Qi, Yue; Tolstik, Elen; Guo, Jinxin; Sheridan, John T.

    2015-01-01

    In the first part of this paper, a model describing photopolymer materials, which incorporates both the physical electromagnetic and photochemical effects taking place, was developed. This model is now validated by applying it to fit experimental data for two different types of photopolymer materials. The first photopolymer material, acrylamide/polyvinyl alcohol, is studied when four photosensitizers are used, i.e. Erythrosine B, Eosin Y, Phloxine B and Rose Bengal. The second type of photopolymer material involves phenanthrenequinone in a polymethylmethacrylate matrix. Using our model, the values of physical parameters, are extracted by numerical fitting experimentally obtained normalized transmittance growth curves. Experimental data sets for different exposure intensities, dye concentrations, and exposure geometries are studied. The advantages of our approach are demonstrated and it is shown that the parameters proposed by us to quantify the absorptive behavior in our model are both physical and can be estimated.

  18. Comparison with CLPX II airborne data using DMRT model

    USGS Publications Warehouse

    Xu, X.; Liang, D.; Andreadis, K.M.; Tsang, L.; Josberger, E.G.

    2009-01-01

    In this paper, we considered a physical-based model which use numerical solution of Maxwell Equations in three-dimensional simulations and apply into Dense Media Radiative Theory (DMRT). The model is validated in two specific dataset from the second Cold Land Processes Experiment (CLPX II) at Alaska and Colorado. The data were all obtain by the Ku-band (13.95GHz) observations using airborne imaging polarimetric scatterometer (POLSCAT). Snow is a densely packed media. To take into account the collective scattering and incoherent scattering, analytical Quasi-Crystalline Approximation (QCA) and Numerical Maxwell Equation Method of 3-D simulation (NMM3D) are used to calculate the extinction coefficient and phase matrix. DMRT equations were solved by iterative solution up to 2nd order for the case of small optical thickness and full multiple scattering solution by decomposing the diffuse intensities into Fourier series was used when optical thickness exceed unity. It was shown that the model predictions agree with the field experiment not only co-polarization but also cross-polarization. For Alaska region, the input snow structure data was obtain by the in situ ground observations, while for Colorado region, we combined the VIC model to get the snow profile. ??2009 IEEE.

  19. Low-order dynamic modeling of the Experimental Breeder Reactor II

    SciTech Connect

    Berkan, R.C. . Dept. of Nuclear Engineering); Upadhyaya, B.R.; Kisner, R.A. )

    1990-07-01

    This report describes the development of a low-order, linear model of the Experimental Breeder Reactor II (EBR-II), including the primary system, intermediate heat exchanger, and steam generator subsystems. The linear model is developed to represent full-power steady state dynamics for low-level perturbations. Transient simulations are performed using model building and simulation capabilities of the computer software Matrix{sub x}. The inherently safe characteristics of the EBR-II are verified through the simulation studies. The results presented in this report also indicate an agreement between the linear model and the actual dynamics of the plant for several transients. Such models play a major role in the learning and in the improvement of nuclear reactor dynamics for control and signal validation studies. This research and development is sponsored by the Advanced Controls Program in the Instrumentation and Controls Division of the Oak Ridge National Laboratory. 17 refs., 67 figs., 15 tabs.

  20. Sub-nanometer Level Model Validation of the SIM Interferometer

    NASA Technical Reports Server (NTRS)

    Korechoff, Robert P.; Hoppe, Daniel; Wang, Xu

    2004-01-01

    The Space Interferometer Mission (SIM) flight instrument will not undergo a full performance, end-to-end system test on the ground due to a number of constraints. Thus, analysis and physics-based models will play a significant role in providing confidence that SIM will meet its science goals on orbit. The various models themselves are validated against the experimental results obtained from the MicroArcsecond Metrology (MAM) testbed adn the Diffraction testbed (DTB). The metric for validation is provided by the SIM astrometric error budget.

  1. Wavelet spectrum analysis approach to model validation of dynamic systems

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaomo; Mahadevan, Sankaran

    2011-02-01

    Feature-based validation techniques for dynamic system models could be unreliable for nonlinear, stochastic, and transient dynamic behavior, where the time series is usually non-stationary. This paper presents a wavelet spectral analysis approach to validate a computational model for a dynamic system. Continuous wavelet transform is performed on the time series data for both model prediction and experimental observation using a Morlet wavelet function. The wavelet cross-spectrum is calculated for the two sets of data to construct a time-frequency phase difference map. The Box-plot, an exploratory data analysis technique, is applied to interpret the phase difference for validation purposes. In addition, wavelet time-frequency coherence is calculated using the locally and globally smoothed wavelet power spectra of the two data sets. Significance tests are performed to quantitatively verify whether the wavelet time-varying coherence is significant at a specific time and frequency point, considering uncertainties in both predicted and observed time series data. The proposed wavelet spectrum analysis approach is illustrated with a dynamics validation challenge problem developed at the Sandia National Laboratories. A comparison study is conducted to demonstrate the advantages of the proposed methodologies over classical frequency-independent cross-correlation analysis and time-independent cross-coherence analysis for the validation of dynamic systems.

  2. Validation techniques of agent based modelling for geospatial simulations

    NASA Astrophysics Data System (ADS)

    Darvishi, M.; Ahmadi, G.

    2014-10-01

    One of the most interesting aspects of modelling and simulation study is to describe the real world phenomena that have specific properties; especially those that are in large scales and have dynamic and complex behaviours. Studying these phenomena in the laboratory is costly and in most cases it is impossible. Therefore, Miniaturization of world phenomena in the framework of a model in order to simulate the real phenomena is a reasonable and scientific approach to understand the world. Agent-based modelling and simulation (ABMS) is a new modelling method comprising of multiple interacting agent. They have been used in the different areas; for instance, geographic information system (GIS), biology, economics, social science and computer science. The emergence of ABM toolkits in GIS software libraries (e.g. ESRI's ArcGIS, OpenMap, GeoTools, etc) for geospatial modelling is an indication of the growing interest of users to use of special capabilities of ABMS. Since ABMS is inherently similar to human cognition, therefore it could be built easily and applicable to wide range applications than a traditional simulation. But a key challenge about ABMS is difficulty in their validation and verification. Because of frequent emergence patterns, strong dynamics in the system and the complex nature of ABMS, it is hard to validate and verify ABMS by conventional validation methods. Therefore, attempt to find appropriate validation techniques for ABM seems to be necessary. In this paper, after reviewing on Principles and Concepts of ABM for and its applications, the validation techniques and challenges of ABM validation are discussed.

  3. Data for model validation summary report. A summary of data for validation and benchmarking of recovery boiler models

    SciTech Connect

    Grace, T.; Lien, S.; Schmidl, W.; Salcudean, M.; Abdullah, Z.

    1997-07-01

    One of the tasks in the project was to obtain data from operating recovery boilers for the purpose of model validation. Another task was to obtain water model data and computer output from University of British Columbia for purposes of benchmarking the UBC model against other codes. In the course of discussions on recovery boiler modeling over the course of this project, it became evident that there would be value in having some common cases for carrying out benchmarking exercises with different recovery boiler models. In order to facilitate such a benchmarking exercise, the data that was obtained on this project for validation and benchmarking purposes has been brought together in a single, separate report. The intent is to make this data available to anyone who may want to use it for model validation. The report contains data from three different cases. Case 1 is an ABBCE recovery boiler which was used for model validation. The data are for a single set of operating conditions. Case 2 is a Babcock & Wilcox recovery boiler that was modified by Tampella. In this data set, several different operating conditions were employed. The third case is water flow data supplied by UBC, along with computational output using the UBC code, for benchmarking purposes.

  4. Validity of NBME Parts I and II for the Selection of Residents: The Case of Orthopaedic Surgery.

    ERIC Educational Resources Information Center

    Case, Susan M.

    The predictive validity of scores on the National Board of Medical Examiners (NBME) Part I and Part II examinations for the selection of residents in orthopaedic surgery was investigated. Use of NBME scores has been criticized because of the time lag between taking Part I and entering residency and because Part I content is not directly linked to…

  5. Concurrent Validity of the WISC-IV and DAS-II in Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Kuriakose, Sarah

    2014-01-01

    Cognitive assessments are used for a variety of research and clinical purposes in children with autism spectrum disorder (ASD). This study establishes concurrent validity of the Wechsler Intelligence Scales for Children-fourth edition (WISC-IV) and Differential Ability Scales-second edition (DAS-II) in a sample of children with ASD with a broad…

  6. Validating the Thinking Styles Inventory-Revised II among Chinese University Students with Hearing Impairment through Test Accommodations

    ERIC Educational Resources Information Center

    Cheng, Sanyin; Zhang, Li-Fang

    2014-01-01

    The present study pioneered in adopting test accommodations to validate the Thinking Styles Inventory-Revised II (TSI-R2; Sternberg, Wagner, & Zhang, 2007) among Chinese university students with hearing impairment. A series of three studies were conducted that drew their samples from the same two universities, in which accommodating test…

  7. Modeling and Validation of Microwave Ablations with Internal Vaporization

    PubMed Central

    Chiang, Jason; Birla, Sohan; Bedoya, Mariajose; Jones, David; Subbiah, Jeyam; Brace, Christopher L.

    2014-01-01

    Numerical simulation is increasingly being utilized for computer-aided design of treatment devices, analysis of ablation growth, and clinical treatment planning. Simulation models to date have incorporated electromagnetic wave propagation and heat conduction, but not other relevant physics such as water vaporization and mass transfer. Such physical changes are particularly noteworthy during the intense heat generation associated with microwave heating. In this work, a numerical model was created that integrates microwave heating with water vapor generation and transport by using porous media assumptions in the tissue domain. The heating physics of the water vapor model was validated through temperature measurements taken at locations 5, 10 and 20 mm away from the heating zone of the microwave antenna in homogenized ex vivo bovine liver setup. Cross-sectional area of water vapor transport was validated through intra-procedural computed tomography (CT) during microwave ablations in homogenized ex vivo bovine liver. Iso-density contours from CT images were compared to vapor concentration contours from the numerical model at intermittent time points using the Jaccard Index. In general, there was an improving correlation in ablation size dimensions as the ablation procedure proceeded, with a Jaccard Index of 0.27, 0.49, 0.61, 0.67 and 0.69 at 1, 2, 3, 4, and 5 minutes. This study demonstrates the feasibility and validity of incorporating water vapor concentration into thermal ablation simulations and validating such models experimentally. PMID:25330481

  8. Using the split Hopkinson pressure bar to validate material models

    PubMed Central

    Church, Philip; Cornish, Rory; Cullis, Ian; Gould, Peter; Lewtas, Ian

    2014-01-01

    This paper gives a discussion of the use of the split-Hopkinson bar with particular reference to the requirements of materials modelling at QinetiQ. This is to deploy validated material models for numerical simulations that are physically based and have as little characterization overhead as possible. In order to have confidence that the models have a wide range of applicability, this means, at most, characterizing the models at low rate and then validating them at high rate. The split Hopkinson pressure bar (SHPB) is ideal for this purpose. It is also a very useful tool for analysing material behaviour under non-shock wave loading. This means understanding the output of the test and developing techniques for reliable comparison of simulations with SHPB data. For materials other than metals comparison with an output stress v strain curve is not sufficient as the assumptions built into the classical analysis are generally violated. The method described in this paper compares the simulations with as much validation data as can be derived from deployed instrumentation including the raw strain gauge data on the input and output bars, which avoids any assumptions about stress equilibrium. One has to take into account Pochhammer–Chree oscillations and their effect on the specimen and recognize that this is itself also a valuable validation test of the material model. PMID:25071238

  9. Modeling and validation of microwave ablations with internal vaporization.

    PubMed

    Chiang, Jason; Birla, Sohan; Bedoya, Mariajose; Jones, David; Subbiah, Jeyam; Brace, Christopher L

    2015-02-01

    Numerical simulation is increasingly being utilized for computer-aided design of treatment devices, analysis of ablation growth, and clinical treatment planning. Simulation models to date have incorporated electromagnetic wave propagation and heat conduction, but not other relevant physics such as water vaporization and mass transfer. Such physical changes are particularly noteworthy during the intense heat generation associated with microwave heating. In this paper, a numerical model was created that integrates microwave heating with water vapor generation and transport by using porous media assumptions in the tissue domain. The heating physics of the water vapor model was validated through temperature measurements taken at locations 5, 10, and 20 mm away from the heating zone of the microwave antenna in homogenized ex vivo bovine liver setup. Cross-sectional area of water vapor transport was validated through intraprocedural computed tomography (CT) during microwave ablations in homogenized ex vivo bovine liver. Iso-density contours from CT images were compared to vapor concentration contours from the numerical model at intermittent time points using the Jaccard index. In general, there was an improving correlation in ablation size dimensions as the ablation procedure proceeded, with a Jaccard index of 0.27, 0.49, 0.61, 0.67, and 0.69 at 1, 2, 3, 4, and 5 min, respectively. This study demonstrates the feasibility and validity of incorporating water vapor concentration into thermal ablation simulations and validating such models experimentally. PMID:25330481

  10. Using the split Hopkinson pressure bar to validate material models.

    PubMed

    Church, Philip; Cornish, Rory; Cullis, Ian; Gould, Peter; Lewtas, Ian

    2014-08-28

    This paper gives a discussion of the use of the split-Hopkinson bar with particular reference to the requirements of materials modelling at QinetiQ. This is to deploy validated material models for numerical simulations that are physically based and have as little characterization overhead as possible. In order to have confidence that the models have a wide range of applicability, this means, at most, characterizing the models at low rate and then validating them at high rate. The split Hopkinson pressure bar (SHPB) is ideal for this purpose. It is also a very useful tool for analysing material behaviour under non-shock wave loading. This means understanding the output of the test and developing techniques for reliable comparison of simulations with SHPB data. For materials other than metals comparison with an output stress v strain curve is not sufficient as the assumptions built into the classical analysis are generally violated. The method described in this paper compares the simulations with as much validation data as can be derived from deployed instrumentation including the raw strain gauge data on the input and output bars, which avoids any assumptions about stress equilibrium. One has to take into account Pochhammer-Chree oscillations and their effect on the specimen and recognize that this is itself also a valuable validation test of the material model. PMID:25071238

  11. Experimental Validation of a Thermoelastic Model for SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.

    2001-01-01

    This study presents results from experimental validation of a recently developed model for predicting the thermomechanical behavior of shape memory alloy hybrid composite (SMAHC) structures, composite structures with an embedded SMA constituent. The model captures the material nonlinearity of the material system with temperature and is capable of modeling constrained, restrained, or free recovery behavior from experimental measurement of fundamental engineering properties. A brief description of the model and analysis procedures is given, followed by an overview of a parallel effort to fabricate and characterize the material system of SMAHC specimens. Static and dynamic experimental configurations for the SMAHC specimens are described and experimental results for thermal post-buckling and random response are presented. Excellent agreement is achieved between the measured and predicted results, fully validating the theoretical model for constrained recovery behavior of SMAHC structures.

  12. Validation of Global Gravitational Field Models in Norway

    NASA Astrophysics Data System (ADS)

    Pettersen, B. R.; Sprlak, M.; Gerlach, C.

    2015-03-01

    We compare global gravitational field models obtained from GOCE to terrestrial datasets over Norway. Models based on the time-wise and the direct approaches are validated against height anomalies, free-air gravity anomalies, and deflections of the vertical. The spectral enhancement method is employed to overcome the spectral inconsistency between the gravitational models and the terrestrial datasets. All models are very similar up to degree/order 160. Higher degrees/orders improved systematically as more observations from GOCE were made available throughout five releases of data. Release 5 models compare well with EGM2008 up to degree/order 220. Validation by height anomalies suggests possible GOCE improvements to the gravity field over Norway between degree/order 100-200.

  13. Open-source MFIX-DEM software for gas-solids flows: Part II Validation studies

    SciTech Connect

    Li, Tingwen; Garg, Rahul; Galvin, Janine; Pannala, Sreekanth

    2012-01-01

    With rapid advancements in computer hardware and numerical algorithms, computational fluid dynamics (CFD) has been increasingly employed as a useful tool for investigating the complex hydrodynamics inherent in multiphase flows. An important step during the development of a CFD model and prior to its application is conducting careful and comprehensive verification and validation studies. Accordingly, efforts to verify and validate the open-source MFIX-DEM software, which can be used for simulating the gas solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles, have been made at the National Energy Technology Laboratory (NETL). In part I of this paper, extensive verification studies were presented and in this part, detailed validation studies of MFIX-DEM are presented. A series of test cases covering a range of gas solids flow applications were conducted. In particular the numerical results for the random packing of a binary particle mixture, the repose angle of a sandpile formed during a side charge process, velocity, granular temperature, and voidage profiles from a bounded granular shear flow, lateral voidage and velocity profiles from a monodisperse bubbling fluidized bed, lateral velocity profiles from a spouted bed, and the dynamics of segregation of a binary mixture in a bubbling bed were compared with available experimental data, and in some instances with empirical correlations. In addition, sensitivity studies were conducted for various parameters to quantify the error in the numerical simulation.

  14. Open-Source MFIX-DEM Software for Gas-Solids Flows: Part II - Validation Studies

    SciTech Connect

    Li, Tingwen

    2012-04-01

    With rapid advancements in computer hardware and numerical algorithms, computational fluid dynamics (CFD) has been increasingly employed as a useful tool for investigating the complex hydrodynamics inherent in multiphase flows. An important step during the development of a CFD model and prior to its application is conducting careful and comprehensive verification and validation studies. Accordingly, efforts to verify and validate the open-source MFIX-DEM software, which can be used for simulating the gas–solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles, have been made at the National Energy Technology Laboratory (NETL). In part I of this paper, extensive verification studies were presented and in this part, detailed validation studies of MFIX-DEM are presented. A series of test cases covering a range of gas–solids flow applications were conducted. In particular the numerical results for the random packing of a binary particle mixture, the repose angle of a sandpile formed during a side charge process, velocity, granular temperature, and voidage profiles from a bounded granular shear flow, lateral voidage and velocity profiles from a monodisperse bubbling fluidized bed, lateral velocity profiles from a spouted bed, and the dynamics of segregation of a binary mixture in a bubbling bed were compared with available experimental data, and in some instances with empirical correlations. In addition, sensitivity studies were conducted for various parameters to quantify the error in the numerical simulation.

  15. Progress in Geant4 Electromagnetic Physics Modelling and Validation

    NASA Astrophysics Data System (ADS)

    Apostolakis, J.; Asai, M.; Bagulya, A.; Brown, J. M. C.; Burkhardt, H.; Chikuma, N.; Cortes-Giraldo, M. A.; Elles, S.; Grichine, V.; Guatelli, S.; Incerti, S.; Ivanchenko, V. N.; Jacquemier, J.; Kadri, O.; Maire, M.; Pandola, L.; Sawkey, D.; Toshito, T.; Urban, L.; Yamashita, T.

    2015-12-01

    In this work we report on recent improvements in the electromagnetic (EM) physics models of Geant4 and new validations of EM physics. Improvements have been made in models of the photoelectric effect, Compton scattering, gamma conversion to electron and muon pairs, fluctuations of energy loss, multiple scattering, synchrotron radiation, and high energy positron annihilation. The results of these developments are included in the new Geant4 version 10.1 and in patches to previous versions 9.6 and 10.0 that are planned to be used for production for run-2 at LHC. The Geant4 validation suite for EM physics has been extended and new validation results are shown in this work. In particular, the effect of gamma-nuclear interactions on EM shower shape at LHC energies is discussed.

  16. Development and Validation of a Mass Casualty Conceptual Model

    PubMed Central

    Culley, Joan M.; Effken, Judith A.

    2012-01-01

    Purpose To develop and validate a conceptual model that provides a framework for the development and evaluation of information systems for mass casualty events. Design The model was designed based on extant literature and existing theoretical models. A purposeful sample of 18 experts validated the model. Open-ended questions, as well as a 7-point Likert scale, were used to measure expert consensus on the importance of each construct and its relationship in the model and the usefulness of the model to future research. Methods Computer-mediated applications were used to facilitate a modified Delphi technique through which a panel of experts provided validation for the conceptual model. Rounds of questions continued until consensus was reached, as measured by an interquartile range (no more than 1 scale point for each item); stability (change in the distribution of responses less than 15% between rounds); and percent agreement (70% or greater) for indicator questions. Findings Two rounds of the Delphi process were needed to satisfy the criteria for consensus or stability related to the constructs, relationships, and indicators in the model. The panel reached consensus or sufficient stability to retain all 10 constructs, 9 relationships, and 39 of 44 indicators. Experts viewed the model as useful (mean of 5.3 on a 7-point scale). Conclusions Validation of the model provides the first step in understanding the context in which mass casualty events take place and identifying variables that impact outcomes of care. Clinical Relevance This study provides a foundation for understanding the complexity of mass casualty care, the roles that nurses play in mass casualty events, and factors that must be considered in designing and evaluating information-communication systems to support effective triage under these conditions. PMID:20487188

  17. Verification and Validation of Model-Based Autonomous Systems

    NASA Technical Reports Server (NTRS)

    Pecheur, Charles; Koga, Dennis (Technical Monitor)

    2001-01-01

    This paper presents a three year project (FY99 to FY01) on the verification and validation of model based autonomous systems. The topics include: 1) Project Profile; 2) Model-Based Autonomy; 3) The Livingstone MIR; 4) MPL2SMV; 5) Livingstone to SMV Translation; 6) Symbolic Model Checking; 7) From Livingstone Models to SMV Models; 8) Application In-Situ Propellant Production; 9) Closed-Loop Verification Principle; 10) Livingstone PathFinder (LPF); 11) Publications and Presentations; and 12) Future Directions. This paper is presented in viewgraph form.

  18. Hydrologic and water quality models: Use, calibration, and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper introduces a special collection of 22 research articles that present and discuss calibration and validation concepts in detail for hydrologic and water quality models by their developers and presents a broad framework for developing the American Society of Agricultural and Biological Engi...

  19. ID Model Construction and Validation: A Multiple Intelligences Case

    ERIC Educational Resources Information Center

    Tracey, Monica W.; Richey, Rita C.

    2007-01-01

    This is a report of a developmental research study that aimed to construct and validate an instructional design (ID) model that incorporates the theory and practice of multiple intelligences (MI). The study consisted of three phases. In phase one, the theoretical foundations of multiple Intelligences and ID were examined to guide the development…

  20. Validating Work Discrimination and Coping Strategy Models for Sexual Minorities

    ERIC Educational Resources Information Center

    Chung, Y. Barry; Williams, Wendi; Dispenza, Franco

    2009-01-01

    The purpose of this study was to validate and expand on Y. B. Chung's (2001) models of work discrimination and coping strategies among lesbian, gay, and bisexual persons. In semistructured individual interviews, 17 lesbians and gay men reported 35 discrimination incidents and their related coping strategies. Responses were coded based on Chung's…

  1. Hydrologic and water quality models: Key calibration and validation topics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a continuation of efforts to provide a common background and platform for accordant development of calibration and validation (C/V) engineering practices, ASABE members worked to determine critical topics related to model C/V, perform a synthesis of the Moriasi et al. (2012) special collection of...

  2. Validation of a tuber blight (Phytophthora infestans) prediction model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage. There is limited published quantitative data on predicting tuber blight. We validated a tuber blight prediction model developed in New York with cultivars Allegany, NY 101, and Katahdin using independent...

  3. Bibliometric Modeling Processes and the Empirical Validity of Lotka's Law.

    ERIC Educational Resources Information Center

    Nicholls, Paul Travis

    1989-01-01

    Examines the elements involved in fitting a bibliometric model to empirical data, proposes a consistent methodology for applying Lotka's law, and presents the results of an empirical test of the methodology. The results are discussed in terms of the validity of Lotka's law and the suitability of the proposed methodology. (49 references) (CLB)

  4. A Model for Investigating Predictive Validity at Highly Selective Institutions.

    ERIC Educational Resources Information Center

    Gross, Alan L.; And Others

    A statistical model for investigating predictive validity at highly selective institutions is described. When the selection ratio is small, one must typically deal with a data set containing relatively large amounts of missing data on both criterion and predictor variables. Standard statistical approaches are based on the strong assumption that…

  5. MODELS FOR SUBMARINE OUTFALL - VALIDATION AND PREDICTION UNCERTAINTIES

    EPA Science Inventory

    This address reports on some efforts to verify and validate dilution models, including those found in Visual Plumes. This is done in the context of problem experience: a range of problems, including different pollutants such as bacteria; scales, including near-field and far-field...

  6. Dynamic modelling and experimental validation of three wheeled tilting vehicles

    NASA Astrophysics Data System (ADS)

    Amati, Nicola; Festini, Andrea; Pelizza, Luigi; Tonoli, Andrea

    2011-06-01

    The present paper describes the study of the stability in the straight running of a three-wheeled tilting vehicle for urban and sub-urban mobility. The analysis was carried out by developing a multibody model in the Matlab/SimulinkSimMechanics environment. An Adams-Motorcycle model and an equivalent analytical model were developed for the cross-validation and for highlighting the similarities with the lateral dynamics of motorcycles. Field tests were carried out to validate the model and identify some critical parameters, such as the damping on the steering system. The stability analysis demonstrates that the lateral dynamic motions are characterised by vibration modes that are similar to that of a motorcycle. Additionally, it shows that the wobble mode is significantly affected by the castor trail, whereas it is only slightly affected by the dynamics of the front suspension. For the present case study, the frame compliance also has no influence on the weave and wobble.

  7. Development, Selection, and Validation of Tumor Growth Models

    NASA Astrophysics Data System (ADS)

    Shahmoradi, Amir; Lima, Ernesto; Oden, J. Tinsley

    In recent years, a multitude of different mathematical approaches have been taken to develop multiscale models of solid tumor growth. Prime successful examples include the lattice-based, agent-based (off-lattice), and phase-field approaches, or a hybrid of these models applied to multiple scales of tumor, from subcellular to tissue level. Of overriding importance is the predictive power of these models, particularly in the presence of uncertainties. This presentation describes our attempt at developing lattice-based, agent-based and phase-field models of tumor growth and assessing their predictive power through new adaptive algorithms for model selection and model validation embodied in the Occam Plausibility Algorithm (OPAL), that brings together model calibration, determination of sensitivities of outputs to parameter variances, and calculation of model plausibilities for model selection. Institute for Computational Engineering and Sciences.

  8. Climate Model Datasets on Earth System Grid II (ESG II)

    DOE Data Explorer

    Earth System Grid (ESG) is a project that combines the power and capacity of supercomputers, sophisticated analysis servers, and datasets on the scale of petabytes. The goal is to provide a seamless distributed environment that allows scientists in many locations to work with large-scale data, perform climate change modeling and simulation,and share results in innovative ways. Though ESG is more about the computing environment than the data, still there are several catalogs of data available at the web site that can be browsed or search. Most of the datasets are restricted to registered users, but several are open to any access.

  9. Aggregating validity indicators embedded in Conners' CPT-II outperforms individual cutoffs at separating valid from invalid performance in adults with traumatic brain injury.

    PubMed

    Erdodi, Laszlo A; Roth, Robert M; Kirsch, Ned L; Lajiness-O'neill, Renee; Medoff, Brent

    2014-08-01

    Continuous performance tests (CPT) provide a useful paradigm to assess vigilance and sustained attention. However, few established methods exist to assess the validity of a given response set. The present study examined embedded validity indicators (EVIs) previously found effective at dissociating valid from invalid performance in relation to well-established performance validity tests in 104 adults with TBI referred for neuropsychological testing. Findings suggest that aggregating EVIs increases their signal detection performance. While individual EVIs performed well at their optimal cutoffs, two specific combinations of these five indicators generally produced the best classification accuracy. A CVI-5A ≥3 had a specificity of .92-.95 and a sensitivity of .45-.54. At ≥4 the CVI-5B had a specificity of .94-.97 and sensitivity of .40-.50. The CVI-5s provide a single numerical summary of the cumulative evidence of invalid performance within the CPT-II. Results support the use of a flexible, multivariate approach to performance validity assessment. PMID:24957927

  10. Finite Element Model Development and Validation for Aircraft Fuselage Structures

    NASA Technical Reports Server (NTRS)

    Buehrle, Ralph D.; Fleming, Gary A.; Pappa, Richard S.; Grosveld, Ferdinand W.

    2000-01-01

    The ability to extend the valid frequency range for finite element based structural dynamic predictions using detailed models of the structural components and attachment interfaces is examined for several stiffened aircraft fuselage structures. This extended dynamic prediction capability is needed for the integration of mid-frequency noise control technology. Beam, plate and solid element models of the stiffener components are evaluated. Attachment models between the stiffener and panel skin range from a line along the rivets of the physical structure to a constraint over the entire contact surface. The finite element models are validated using experimental modal analysis results. The increased frequency range results in a corresponding increase in the number of modes, modal density and spatial resolution requirements. In this study, conventional modal tests using accelerometers are complemented with Scanning Laser Doppler Velocimetry and Electro-Optic Holography measurements to further resolve the spatial response characteristics. Whenever possible, component and subassembly modal tests are used to validate the finite element models at lower levels of assembly. Normal mode predictions for different finite element representations of components and assemblies are compared with experimental results to assess the most accurate techniques for modeling aircraft fuselage type structures.