BELSHER JD; MEINERT FL
2009-12-07
This document presents the differences between two HLW glass formulation models (GFM): The 1996 GFM and 2009 GFM. A glass formulation model is a collection of glass property correlations and associated limits, as well as model validity and solubility constraints; it uses the pretreated HLW feed composition to predict the amount and composition of glass forming additives necessary to produce acceptable HLW glass. The 2009 GFM presented in this report was constructed as a nonlinear optimization calculation based on updated glass property data and solubility limits described in PNNL-18501 (2009). Key mission drivers such as the total mass of HLW glass and waste oxide loading are compared between the two glass formulation models. In addition, a sensitivity study was performed within the 2009 GFM to determine the effect of relaxing various constraints on the predicted mass of the HLW glass.
Rheology of Model Dough Formulation
NASA Astrophysics Data System (ADS)
Desai, Kiran; Lele, Smita; Lele, Ashish
2008-07-01
Dough is generally considered a viscoelastic material, and its elasticity is attributed to the hydrated gluten matrix. Since starch is a major constituent of flour (˜70 wt% on dry basis) we may expect it to contribute to dough rheology in a non-trivial manner. Considering dough to belong to the generic class of soft solid materials, we use the Strain-Rate Frequency Superposition (SRFS) technique to study rheology of various model dough compositions in which the starch/gluten ratio is systematically varied from 100/0 to 0/100. We find that for compositions containing 0-25% gluten the SRFS superposition principle works well, while for compositions containing greater than 25% gluten the quality of SRFS mastercurves deteriorates gradually. Thus we propose that starch particles contribute substantially to the rheology of dough containing up to 25% gluten.
Gurson's Model: ALE Formulation and Strain Localization
Cunda, Luiz A. B. da; Creus, Guillermo J.
2007-05-17
This paper presents a brief review of Gurson's damage model, employed to describes the strength degradation in ductile metals submitted to large plastic deformations. The damage model is applied using finite elements and an Arbitrary Lagrangian-Eulerian formulation (ALE), to ensure a better quality to the finite elements mesh. The study of the combined application of ALE and Gurson approach to damage modeling and strain localization is the object of this paper.
Renormalization of stochastic lattice models: basic formulation.
Haselwandter, Christoph A; Vvedensky, Dimitri D
2007-10-01
We describe a general method for the multiscale analysis of stochastic lattice models. Beginning with a lattice Langevin formulation of site fluctuations, we derive stochastic partial differential equations by regularizing the transition rules of the model. Subsequent coarse graining is accomplished by calculating renormalization-group (RG) trajectories from initial conditions determined by the regularized atomistic models. The RG trajectories correspond to hierarchies of continuum equations describing lattice models over expanding length and time scales. These continuum equations retain a quantitative connection over different scales, as well as to the underlying atomistic dynamics. This provides a systematic method for the derivation of continuum equations from the transition rules of lattice models for any length and time scales. As an illustration we consider the one-dimensional (1D) Wolf-Villain (WV) model [Europhys. Lett. 13, 389 (1990)]. The RG analysis of this model, which we develop in detail, is generic and can be applied to a wide range of conservative lattice models. The RG trajectory of the 1D WV model shows a complex crossover sequence of linear and nonlinear stochastic differential equations, which is in excellent agreement with kinetic Monte Carlo simulations of this model. We conclude by discussing possible applications of the multiscale method described here to other nonequilibrium systems. PMID:17994944
A Formulation of the Interactive Evaluation Model
Walsh, Peter J.; Awad-Edwards, Roger; Engelhardt, K. G.; Perkash, Inder
1985-01-01
The development of highly technical devices for specialized users requires continual feedback from potential users to the project team designing the device to assure that a useful product will result. This necessity for user input is the basis for the Interactive Evaluation Model which has been applied to complex computer assisted robotic aids for individuals with disabilities and has wide application to the development of a variety of technical devices. We present a preliminary mathematical formulation of the Interactive Evaluation Model which maximizes the rate of growth toward success, at a constant cost rate, of the efforts of a team having the diverse expertises needed to produce a complex technical product. Close interaction is simulated by a growth rate which is a multiplicative product involving the number of participants within a given class of necessary expertise and evaluation is included by demanding that users form one of the necessary classes. In the multipliers, the number of class participants is raised to a power termed the class weight exponent. In the simplest case, the optimum participant number varies as the ratio of the class weight exponent to the average class cost. An illustrative example, based on our experience with medical care assistive aids, shows the dramatic cost reduction possible with users on the team.
Formulation and Application of the Generalized Multilevel Facets Model
ERIC Educational Resources Information Center
Wang, Wen-Chung; Liu, Chih-Yu
2007-01-01
In this study, the authors develop a generalized multilevel facets model, which is not only a multilevel and two-parameter generalization of the facets model, but also a multilevel and facet generalization of the generalized partial credit model. Because the new model is formulated within a framework of nonlinear mixed models, no efforts are…
Model Formulation for Physics Problem Solving. Draft.
ERIC Educational Resources Information Center
Novak, Gordon S., Jr.
The major task in solving a physics problem is to construct an appropriate model of the problem in terms of physical principles. The functions performed by such a model, the information which needs to be represented, and the knowledge used in selecting and instantiating an appropriate model are discussed. An example of a model for a mechanics…
AERMOD: MODEL FORMULATION AND EVALUATION RESULTS
AERMOD is an advanced plume model that incorporates updated treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions. This paper presents an overview of AERMOD's features relative to ISCST3.
AERM...
AERMOD: Model formulation and evaluation results
Paine, R.J.; Lee, R.; Brode, R.; Wilson, R.; Cimorelli, A.; Perry, S.G.; Weil, J.; Venkatram, A.; Peters, W.
1999-07-01
AERMOD is an advanced plume model that incorporates updated treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions. This paper presents an overview of AERMOD's features relative to ISCST3. AERMOD has been evaluated on 10 databases, which include flat and hilly terrain areas, urban and rural sites, and a mixture of tracer experiments as well as routine monitoring networks with a limited number of fixed monitoring sites. This paper presents a summary of the evaluation results of AERMOD with these diverse databases.
AERMOD: Model formulation and evaluation results
Paine, R.; Lee, R.; Brode, R.; Wilson, R.; Cimorelli, A.
1999-07-01
AERMOD is an advanced plume model that incorporates update treatment of the boundary treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions. This paper presents an overview of AERMOD`s features relatives of ISCST3. AERMOD has been evaluated on 10 databases, which include flat and hilly terrain areas, urban and rural sites, and a mixture of tracer experiments as well as routine monitoring networks with a limited number of fixed monitoring sites. This paper presents a summary of the evaluation results of AERMOD with these diverse databases.
Stable and flux-conserved meshfree formulation to model shocks
NASA Astrophysics Data System (ADS)
Roth, Michael J.; Chen, Jiun-Shyan; Slawson, Thomas R.; Danielson, Kent T.
2016-05-01
Accurate shock modeling requires that two critical issues be addressed: (1) correct representation of the essential shock physics, and (2) control of Gibbs phenomenon oscillation at the discontinuity. In this work a stable (oscillation limiting) and flux-conserved formulation under the reproducing kernel particle method is developed for shock modeling. A smoothed flux divergence is constructed under the framework of stabilized conforming nodal integration, which is locally-enriched with a Riemann solution to satisfy the entropy production constraints. This Riemann-enriched flux divergence is embedded into the reproducing kernel formulation through a velocity correction that also provides oscillation control at the shock. The correction is constrained to the shock region by an automatic shock detection algorithm that is constructed using the intrinsic spectral decomposition feature of the reproducing kernel approximation. Several numerical examples are provided to verify accuracy of the proposed formulation.
Mechanistic model and analysis of doxorubicin release from liposomal formulations.
Fugit, Kyle D; Xiang, Tian-Xiang; Choi, Du H; Kangarlou, Sogol; Csuhai, Eva; Bummer, Paul M; Anderson, Bradley D
2015-11-10
Reliable and predictive models of drug release kinetics in vitro and in vivo are still lacking for liposomal formulations. Developing robust, predictive release models requires systematic, quantitative characterization of these complex drug delivery systems with respect to the physicochemical properties governing the driving force for release. These models must also incorporate changes in release due to the dissolution media and methods employed to monitor release. This paper demonstrates the successful development and application of a mathematical mechanistic model capable of predicting doxorubicin (DXR) release kinetics from liposomal formulations resembling the FDA-approved nanoformulation DOXIL® using dynamic dialysis. The model accounts for DXR equilibria (e.g. self-association, precipitation, ionization), the change in intravesicular pH due to ammonia release, and dialysis membrane transport of DXR. The model was tested using a Box-Behnken experimental design in which release conditions including extravesicular pH, ammonia concentration in the release medium, and the dilution of the formulation (i.e. suspension concentration) were varied. Mechanistic model predictions agreed with observed DXR release up to 19h. The predictions were similar to a computer fit of the release data using an empirical model often employed for analyzing data generated from this type of experimental design. Unlike the empirical model, the mechanistic model was also able to provide reasonable predictions of release outside the tested design space. These results illustrate the usefulness of mechanistic modeling to predict drug release from liposomal formulations in vitro and its potential for future development of in vitro - in vivo correlations for complex nanoformulations. PMID:26310713
BF Models in Dual Formulations of Linearized Gravity
Bizdadea, Constantin; Cioroianu, Eugen M.; Danehkar, Ashbiz; Iordache, Marius; Saliu, Solange O.; Sararu, Silviu C.
2009-05-22
The case of couplings in D = 5 between a simple, maximal BF model and the dual formulation of linearized gravity is considered. All the possible interactions are exhausted by means of computing the 'free' local BRST cohomology in ghost number zero.
On the formulation of a crystal plasticity model.
Marin, Esteban B.
2006-08-01
This report presents the formulation of a crystal elasto-viscoplastic model and the corresponding integration scheme. The model is suitable to represent the isothermal, anisotropic, large deformation of polycrystalline metals. The formulation is an extension of a rigid viscoplastic model to account for elasticity effects, and incorporates a number of changes with respect to a previous formulation [Marin & Dawson, 1998]. This extension is formally derived using the well-known multiplicative decomposition of the deformation gradient into an elastic and plastic components, where the elastic part is additionally decomposed into the elastic stretch V{sup e} and the proper orthogonal R{sup e} tensors. The constitutive equations are written in the intermediate, stress-free configuration obtained by unloading the deformed crystal through the elastic stretch V{sup e-}. The model is framed in a thermodynamic setting, and developed initially for large elastic strains. The crystal equations are then specialized to the case of small elastic strains, an assumption typically valid for metals. The developed integration scheme is implicit and proceeds by separating the spherical and deviatoric crystal responses. An ''approximate'' algorithmic material moduli is also derived for applications in implicit numerical codes. The model equations and their integration procedure have been implemented in both a material point simulator and a commercial finite element code. Both implementations are validated by solving a number of examples involving aggregates of either face centered cubic (FCC) or hexagonal close-packed (HCP) crystals subjected to different loading paths.
Finite element formulation of biphasic poroviscoelastic model for articular cartilage.
Suh, J K; Bai, S
1998-04-01
The purpose of the present study was to develop a computationally efficient finite element model that could be useful for parametric analysis of the biphasic poroviscoelastic (BPVE) behavior of articular cartilage under various loading conditions. The articular cartilage was modeled as the BPVE mixture of a porous, linear viscoelastic, and incompressible solid and an inviscid and incompressible fluid. A finite element (FE) formulation of the BPVE model was developed using two different algorithms, the continuous and discrete spectrum relaxation functions for the viscoelasticity of the solid matrix. These algorithms were applied to the creep and stress relaxation responses to the confined compression of articular cartilage, and a comparison of their performances was made. It was found that the discrete spectrum algorithm significantly saved CPU time and memory, as compared to the continuous spectrum algorithm. The consistency analysis for the present FE formulation was performed in comparison with the IMSL, a commercially available numerical software package. It was found that the present FE formulation yielded consistent results in predicting model behavior, whereas the IMSL subroutine produced inconsistent results in the velocity field, and thereby in the strain calculation. PMID:10412380
Generic element formulation for modelling bolted lap joints
NASA Astrophysics Data System (ADS)
Ahmadian, Hamid; Jalali, Hassan
2007-07-01
Joints have significant effects on the dynamic response of the assembled structures due to existence of two non-linear mechanisms in their interface, namely slipping and slapping. These mechanisms affect the structural response by adding considerable damping into the structure and lowering the natural frequencies due to the stiffness softening. Neglecting these effects in modelling of joints produces errors in predictions of the structure responses. In this paper, a non-linear generic element formulation is developed for modelling bolted lap joints. The generic element is formed by satisfying all conditions that are known for a joint interface and hence providing a non-linear parametric formulation for the families of allowable joint models. Dynamic response of the developed model for the assembled structure including the generic joint interface element is obtained using the incremental harmonic balance (IHB) method. The generic parameters of the joint are identified by minimising the difference between the model response obtained from IHB method and the observed behaviour of the structure. The procedure is demonstrated by modelling an actual structure containing a single lap bolted joint in the middle. The frequency responses of the structure around the first two resonance frequencies are measured by exciting the structure using a sinusoidal force at each individual frequency. The measured responses are compared with the predictions of the model containing a parametric generic joint element. The parameters of the joint interface model are successfully identified by minimising the difference between the measured responses and the model predictions.
Gauge invariant formulation and bosonisation of the Schwinger model
NASA Astrophysics Data System (ADS)
Kijowski, J.; Rudolph, G.; Rudolph, M.
1998-02-01
The functional integral of the massless Schwinger model in (1+1) dimensions is reduced to an integral in terms of local gauge invariant quantities. It turns out that this approach leads to a natural bosonisation scheme, yielding, in particular the famous ``bosonisation rule'' and giving some deeper insight into the nature of the bosonisation phenomenon. As an application, the chiral anomaly is calculated within this formulation.
The Pantex Process model: Formulations of the evaluation planning module
JONES,DEAN A.; LAWTON,CRAIG R.; LIST,GEORGE FISHER; TURNQUIST,MARK ALAN
1999-12-01
This paper describes formulations of the Evaluation Planning Module that have been developed since its inception. This module is one of the core algorithms in the Pantex Process Model, a computerized model to support production planning in a complex manufacturing system at the Pantex Plant, a US Department of Energy facility. Pantex is responsible for three major DOE programs -- nuclear weapons disposal, stockpile evaluation, and stockpile maintenance -- using shared facilities, technicians, and equipment. The model reflects the interactions of scheduling constraints, material flow constraints, and the availability of required technicians and facilities.
Space-time formulation for finite element modeling of superconductors
Ashworth, Stephen P; Grilli, Francesco; Sirois, Frederic; Laforest, Marc
2008-01-01
In this paper we present a new model for computing the current density and field distributions in superconductors by means of a periodic space-time formulation for finite elements (FE). By considering a space dimension as time, we can use a static model to solve a time dependent problem. This allows overcoming one of the major problems of FE modeling of superconductors: the length of simulations, even for relatively simple cases. We present our first results and compare them to those obtained with a 'standard' time-dependent method and with analytical solutions.
EMPIRICAL MODEL FOR FORMULATION OF CRYSTAL-TOLERANT HLW GLASSES
KRUGER AA; MATYAS J; HUCKLEBERRY AR; VIENNA JD; RODRIGUEZ CA
2012-03-07
Historically, high-level waste (HLW) glasses have been formulated with a low liquideus temperature (T{sub L}), or temperature at which the equilibrium fraction of spinel crystals in the melt is below 1 vol % (T{sub 0.01}), nominally below 1050 C. These constraints cannot prevent the accumulation of large spinel crystals in considerably cooler regions ({approx} 850 C) of the glass discharge riser during melter idling and significantly limit the waste loading, which is reflected in a high volume of waste glass, and would result in high capital, production, and disposal costs. A developed empirical model predicts crystal accumulation in the riser of the melter as a function of concentration of spinel-forming components in glass, and thereby provides guidance in formulating crystal-tolerant glasses that would allow high waste loadings by keeping the spinel crystals small and therefore suspended in the glass.
EMPIRICAL MODEL FOR FORMULATION OF CRYSTAL-TOLERANT HLW GLASSES
Matyas, Josef; Huckleberry, Adam R.; Rodriguez, Carmen P.; Vienna, John D.; Kruger, Albert A.
2012-11-07
Historically, high-level waste (HLW) glasses have been formulated with a low liquidus temperature (TL), or temperature at which the equilibrium fraction of spinel crystals in the melt is below 1 vol % (T0.01), nominally below 1050°C. These constraints cannot prevent the accumulation of large spinel crystals in considerably cooler regions (~ 850°C) of the glass discharge riser during melter idling and significantly limit the waste loading, which is reflected in a high volume of waste glass, and would result in high capital, production, and disposal costs. A developed empirical model predicts crystal accumulation in the riser of the melter as a function of concentration of spinel-forming components in glass, and thereby provides guidance in formulating crystal-tolerant glasses that would allow high waste loadings by keeping the spinel crystals small and therefore suspended in the glass.
Explicit formulation of titration models for isothermal titration calorimetry.
Poon, Gregory M K
2010-05-15
Isothermal titration calorimetry (ITC) produces a differential heat signal with respect to the total titrant concentration. This feature gives ITC excellent sensitivity for studying the thermodynamics of complex biomolecular interactions in solution. Currently, numerical methods for data fitting are based primarily on indirect approaches rooted in the usual practice of formulating biochemical models in terms of integrated variables. Here, a direct approach is presented wherein ITC models are formulated and solved as numerical initial value problems for data fitting and simulation purposes. To do so, the ITC signal is cast explicitly as a first-order ordinary differential equation (ODE) with total titrant concentration as independent variable and the concentration of a bound or free ligand species as dependent variable. This approach was applied to four ligand-receptor binding and homotropic dissociation models. Qualitative analysis of the explicit ODEs offers insights into the behavior of the models that would be inaccessible to indirect methods of analysis. Numerical ODEs are also highly compatible with regression analysis. Since solutions to numerical initial value problems are straightforward to implement on common computing platforms in the biochemical laboratory, this method is expected to facilitate the development of ITC models tailored to any experimental system of interest. PMID:20100451
Modeling downstream fining in sand-bed rivers. I: Formulation
Wright, S.; Parker, G.
2005-01-01
In this paper a numerical modeling formulation is presented for simulation of the development of the longitudinal profile and bed sediment distribution in sand-bed rivers. The objective of the model application, which is presented in the companion paper (Wright and Parker, 2005), is to study the development of two characteristics of large, low-slope, sand-bed rivers: (1) a downstream decrease in bed slope (i.e. concave upward longitudinal profile) and (2) a downstream decrease in characteristic bed sediment diameter (e.g. the median bed surface size D50). Three mechanisms that lead to an upward concave profile and downstream fining are included in the modeling formulation: (1) a delta prograding into standing water at the downstream boundary, (2) sea-level rise, and (3) tectonic subsidence. In the companion paper (Wright and Parker, 2005) the model is applied to simulate the development of the longitudinal profile and downstream fining in sand-bed rivers flowing into the ocean during the past 5000 years of relatively slow sea-level rise. ?? 2005 International Association of Hydraulic Engineering and Research.
Retrostructural model to predict biomass formulations for barrier performance.
Zhu Ryberg, Y Z; Edlund, U; Albertsson, A-C
2012-08-13
Barrier performance and retrostructural modeling of the macromolecular components demonstrate new design principles for film formulations based on renewable wood hydrolysates. Hardwood hydrolysates, which contain a fair share of lignin coexisting with poly- and oligosaccharides, offer excellent oxygen-barrier performance. A Hansen solubility parameter (HSP) model has been developed to convert the complex hydrolysate structural compositions into relevant matrix oxygen-permeability data allowing a systematic prediction of how the biomass should be formulated to generate an efficient barrier. HSP modeling suggests that the molecular packing ability plays a key role in the barrier performance. The actual size and distribution of free volume holes in the matrices were quantified in the subnanometer scale with Positron annihilation lifetime spectroscopy (PALS) verifying the affinity-driven assembly of macromolecular segments in a densely packed morphology and regulating the diffusion of small permeants through the matrix. The model is general and can be adapted to determine the macromolecular affinities of any hydrolysate biomass based on chemical composition. PMID:22804452
On matrix model formulations of noncommutative Yang-Mills theories
Azeyanagi, Tatsuo; Hirata, Tomoyoshi; Hanada, Masanori
2008-11-15
We study the stability of noncommutative spaces in matrix models and discuss the continuum limit which leads to the noncommutative Yang-Mills theories. It turns out that most noncommutative spaces in bosonic models are unstable. This indicates perturbative instability of fuzzy R{sup D} pointed out by Van Raamsdonk and Armoni et al. persists to nonperturbative level in these cases. In this sense, these bosonic noncommutative Yang-Mills theories are not well-defined, or at least their matrix model formulations studied in this paper do not work. We also show that noncommutative backgrounds are stable in a supersymmetric matrix model deformed by a cubic Myers term, though the deformation itself breaks supersymmetry.
A modeling approach to thermoplastic pultrusion. I - Formulation of models
NASA Astrophysics Data System (ADS)
Astrom, B. T.; Pipes, R. B.
1993-06-01
Models to predict temperature and pressure distributions within a thermoplastic composed as it travels through a pultrusion line and a model to predict the pulling resistance of a die are presented and discussed. A set of mathematical models of the thermoplastic pultrusion process comprising temperature, pressure, and pulling force models are discussed and extensively verified with experimental data.
A MULTILAYER BIOCHEMICAL DRY DEPOSITION MODEL 1. MODEL FORMULATION
A multilayer biochemical dry deposition model has been developed based on the NOAA Multilayer Model (MLM) to study gaseous exchanges between the soil, plants, and the atmosphere. Most of the parameterizations and submodels have been updated or replaced. The numerical integration ...
Affine group formulation of the Standard Model coupled to gravity
Chou, Ching-Yi; Ita, Eyo; Soo, Chopin
2014-04-15
In this work we apply the affine group formalism for four dimensional gravity of Lorentzian signature, which is based on Klauder’s affine algebraic program, to the formulation of the Hamiltonian constraint of the interaction of matter and all forces, including gravity with non-vanishing cosmological constant Λ, as an affine Lie algebra. We use the hermitian action of fermions coupled to gravitation and Yang–Mills theory to find the density weight one fermionic super-Hamiltonian constraint. This term, combined with the Yang–Mills and Higgs energy densities, are composed with York’s integrated time functional. The result, when combined with the imaginary part of the Chern–Simons functional Q, forms the affine commutation relation with the volume element V(x). Affine algebraic quantization of gravitation and matter on equal footing implies a fundamental uncertainty relation which is predicated upon a non-vanishing cosmological constant. -- Highlights: •Wheeler–DeWitt equation (WDW) quantized as affine algebra, realizing Klauder’s program. •WDW formulated for interaction of matter and all forces, including gravity, as affine algebra. •WDW features Hermitian generators in spite of fermionic content: Standard Model addressed. •Constructed a family of physical states for the full, coupled theory via affine coherent states. •Fundamental uncertainty relation, predicated on non-vanishing cosmological constant.
Differential geometry based solvation model I: Eulerian formulation.
Chen, Zhan; Baker, Nathan A; Wei, G W
2010-11-01
This paper presents a differential geometry based model for the analysis and computation of the equilibrium property of solvation. Differential geometry theory of surfaces is utilized to define and construct smooth interfaces with good stability and differentiability for use in characterizing the solvent-solute boundaries and in generating continuous dielectric functions across the computational domain. A total free energy functional is constructed to couple polar and nonpolar contributions to the salvation process. Geometric measure theory is employed to rigorously convert a Lagrangian formulation of the surface energy into an Eulerian formulation so as to bring all energy terms into an equal footing. By minimizing the total free energy functional, we derive coupled generalized Poisson-Boltzmann equation (GPBE) and generalized geometric flow equation (GGFE) for the electrostatic potential and the construction of realistic solvent-solute boundaries, respectively. By solving the coupled GPBE and GGFE, we obtain the electrostatic potential, the solvent-solute boundary profile, and the smooth dielectric function, and thereby improve the accuracy and stability of implicit solvation calculations. We also design efficient second order numerical schemes for the solution of the GPBE and GGFE. Matrix resulted from the discretization of the GPBE is accelerated with appropriate preconditioners. An alternative direct implicit (ADI) scheme is designed to improve the stability of solving the GGFE. Two iterative approaches are designed to solve the coupled system of nonlinear partial differential equations. Extensive numerical experiments are designed to validate the present theoretical model, test computational methods, and optimize numerical algorithms. Example solvation analysis of both small compounds and proteins are carried out to further demonstrate the accuracy, stability, efficiency and robustness of the present new model and numerical approaches. Comparison is given to
Radiolysis Model Formulation for Integration with the Mixed Potential Model
Buck, Edgar C.; Wittman, Richard S.
2014-07-10
The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development activities related to storage, transportation, and disposal of used nuclear fuel (UNF) and high-level radioactive waste. Within the UFDC, the components for a general system model of the degradation and subsequent transport of UNF is being developed to analyze the performance of disposal options [Sassani et al., 2012]. Two model components of the near-field part of the problem are the ANL Mixed Potential Model and the PNNL Radiolysis Model. This report is in response to the desire to integrate the two models as outlined in [Buck, E.C, J.L. Jerden, W.L. Ebert, R.S. Wittman, (2013) “Coupling the Mixed Potential and Radiolysis Models for Used Fuel Degradation,” FCRD-UFD-2013-000290, M3FT-PN0806058
(De)compaction of porous viscoelastoplastic media: Model formulation
NASA Astrophysics Data System (ADS)
Yarushina, Viktoriya M.; Podladchikov, Yuri Y.
2015-06-01
A nonlinear viscoelastoplastic theory is developed for porous rate-dependent materials filled with a fluid in the presence of gravity. The theory is based on a rigorous thermodynamic formalism suitable for path-dependent and irreversible processes. Incremental evolution equations for porosity, Darcy's flux, and volumetric deformation of the matrix represent the simplest generalization of Biot's equations. Expressions for pore compressibility and effective bulk viscosity are given for idealized cylindrical and spherical pore geometries in an elastic-viscoplastic material with low pore concentration. We show that plastic yielding around pores leads to decompaction weakening and an exponential creep law. Viscous and plastic end-members of our model are consistent with experimentally verified models. In the poroelastic limit, our constitutive equations reproduce the exact Gassmann's relations, Biot's theory, and Terzaghi's effective stress law. The nature of the discrepancy between Biot's model and the True Porous Media theory is clarified. Our model provides a unified and consistent formulation for the elastic, viscous, and plastic cases that have previously been described by separate "end-member" models.
A Bayesian state-space formulation of dynamic occupancy models.
Royle, J Andrew; Kéry, Marc
2007-07-01
Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by non-detection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and WinBUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site
A Bayesian state-space formulation of dynamic occupancy models
Royle, J. Andrew; Kery, M.
2007-01-01
Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by nondetection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and Win BUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site
Differential geometry based solvation model. III. Quantum formulation
Chen, Zhan; Wei, Guo-Wei
2011-01-01
to many other classic and quantum models. By using experimental data, we show that the present quantum formulation of our differential geometry based multiscale solvation model improves the prediction of our earlier models, and outperforms some explicit solvation model. PMID:22112067
The integrated Earth System Model Version 1: formulation and functionality
Collins, William D.; Craig, Anthony P.; Truesdale, John E.; Di Vittorio, Alan; Jones, Andrew D.; Bond-Lamberty, Benjamin; Calvin, Katherine V.; Edmonds, James A.; Kim, Son H.; Thomson, Allison M.; Patel, Pralit L.; Zhou, Yuyu; Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E.; Chini, Louise M.; Hurtt, George C.
2015-07-23
The integrated Earth System Model (iESM) has been developed as a new tool for pro- jecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling in- frastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a sin- gle simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore- omitted feedbacks between natural and societal drivers, we can improve scientific under- standing of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper de- scribes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.
The integrated Earth system model version 1: formulation and functionality
Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; et al
2015-07-23
The integrated Earth system model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an integrated assessment model (IAM) and an Earth system model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species (SLS), land use and land cover change (LULCC), and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. Themore » iESM project integrates the economic and human-dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.« less
The integrated Earth system model version 1: formulation and functionality
NASA Astrophysics Data System (ADS)
Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; Patel, P.; Zhou, Y.; Mao, J.; Shi, X.; Thornton, P. E.; Chini, L. P.; Hurtt, G. C.
2015-07-01
The integrated Earth system model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an integrated assessment model (IAM) and an Earth system model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human-Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species (SLS), land use and land cover change (LULCC), and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human-dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human-Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.
A Quasi-Equilibrium Tropical Circulation Model--Formulation*.
NASA Astrophysics Data System (ADS)
Neelin, J. David; Zeng, Ning
2000-06-01
A class of model for simulation and theory of the tropical atmospheric component of climate variations is introduced. These models are referred to as quasi-equilibrium tropical circulation models, or QTCMs, because they make use of approximations associated with quasi-equilibrium (QE) convective parameterizations. Quasi-equilibrium convective closures tend to constrain the vertical temperature profile in convecting regions. This can be used to generate analytical solutions for the large-scale flow under certain approximations. A tropical atmospheric model of intermediate complexity is constructed by using the analytical solutions as the first basis function in a Galerkin representation of vertical structure. This retains much of the simplicity of the analytical solutions, while retaining full nonlinearity, vertical momentum transport, departures from QE, and a transition between convective and nonconvective zones based on convective available potential energy. The atmospheric model is coupled to a one-layer land surface model with interactive soil moisture and simulates its own tropical climatology. In the QTCM version presented here, the vertical structure of temperature variations is truncated to a single profile associated with deep convection. Though designed to be accurate in and near regions dominated by deep convection, the model simulates the tropical and subtropical climatology reasonably well, and even has a qualitative representation of midlatitude storm tracks.The model is computationally economical, since part of the solution has been carried out analytically, but the main advantage is relative simplicity of analysis under certain conditions. The formulation suggests a slightly different way of looking at the tropical atmosphere than has been traditional in tropical meteorology. While convective scales are unstable, the large-scale motions evolve with a positive effective stratification that takes into account the partial cancellation of adiabatic
Gaikwad, Vinod L; Bhatia, Neela M; Desai, Sujit A; Bhatia, Manish S
2016-10-20
Quantitative structure property relationship (QSPR) is used to relate the excipient descriptors with the formulation properties. A QSPR model is developed by regression analysis of selected descriptors contributing towards the targeted formulation properties. Developed QSPR model is validated by the true external method where it showed good accuracy and precision in predicting the formulation composition as experimental t90% (61.35min) is observed very close to predicted t90% (67.37min). Hence, QSPR approach saves resources by predicting drug release from an unformulated formulation; avoiding repetitive trials in the development of a new formulation and/or optimization of existing one. PMID:27474604
NASA Astrophysics Data System (ADS)
Herman, J. D.; Reed, P. M.; Wagener, T.
2012-12-01
Lumped rainfall-runoff models are widely used for flow prediction, but a long-recognized need exists for diagnostic tools to determine whether the process-level behavior of a model aligns with the expectations inherent in its formulation. To this end, we develop a comprehensive exploration of dominant processes in the Hymod, HBV, and Sacramento Soil Moisture Accounting (SAC-SMA) model structures. Model controls are isolated using time-varying Sobol sensitivity analysis for twelve MOPEX watersheds in the eastern United States over a ten-year period. Sensitivity indices are visualized along gradients of observed precipitation and flow characteristics to identify key behavioral differences between the three models and to connect these back to the models' underlying assumptions. Results indicate that dominant processes strongly depend on time-varying hydroclimatic conditions. Parameters associated with surface processes generally dominate under dry conditions, while parameters associated with routing processes dominate under high flow conditions. The results highlight significant inter-model differences in dominant processes, even in models sharing the same process formulation (e.g., the soil moisture formulation in the Hymod and HBV models). The dominant processes identified are often counterintuitive; even these simple models represent complex, nonlinear systems, and the links between formulation and behavior are very difficult to discern a priori as complexity increases. Scrutinizing the links between model formulation and behavior becomes an important diagnostic approach, particularly in applications such as predictions under change where it is critical to identify how a model's dominant processes shift under hydrologic extremes. Sensitive parameters in the (a) Hymod, (b) SAC-SMA, and (c) HBV watershed models as conditions change from dry to wet. This is a qualitative summary of the time-varying sensitivity indices from twelve watersheds across a range of
ERIC Educational Resources Information Center
Natesan, Prathiba; Limbers, Christine; Varni, James W.
2010-01-01
The present study presents the formulation of graded response models in the multilevel framework (as nonlinear mixed models) and demonstrates their use in estimating item parameters and investigating the group-level effects for specific covariates using Bayesian estimation. The graded response multilevel model (GRMM) combines the formulation of…
Differential geometry based solvation model II: Lagrangian formulation.
Chen, Zhan; Baker, Nathan A; Wei, G W
2011-12-01
Solvation is an elementary process in nature and is of paramount importance to more sophisticated chemical, biological and biomolecular processes. The understanding of solvation is an essential prerequisite for the quantitative description and analysis of biomolecular systems. This work presents a Lagrangian formulation of our differential geometry based solvation models. The Lagrangian representation of biomolecular surfaces has a few utilities/advantages. First, it provides an essential basis for biomolecular visualization, surface electrostatic potential map and visual perception of biomolecules. Additionally, it is consistent with the conventional setting of implicit solvent theories and thus, many existing theoretical algorithms and computational software packages can be directly employed. Finally, the Lagrangian representation does not need to resort to artificially enlarged van der Waals radii as often required by the Eulerian representation in solvation analysis. The main goal of the present work is to analyze the connection, similarity and difference between the Eulerian and Lagrangian formalisms of the solvation model. Such analysis is important to the understanding of the differential geometry based solvation model. The present model extends the scaled particle theory of nonpolar solvation model with a solvent-solute interaction potential. The nonpolar solvation model is completed with a Poisson-Boltzmann (PB) theory based polar solvation model. The differential geometry theory of surfaces is employed to provide a natural description of solvent-solute interfaces. The optimization of the total free energy functional, which encompasses the polar and nonpolar contributions, leads to coupled potential driven geometric flow and PB equations. Due to the development of singularities and nonsmooth manifolds in the Lagrangian representation, the resulting potential-driven geometric flow equation is embedded into the Eulerian representation for the purpose of
Differential geometry based solvation model II: Lagrangian formulation
Chen, Zhan; Baker, Nathan A.; Wei, G. W.
2010-01-01
Solvation is an elementary process in nature and is of paramount importance to more sophisticated chemical, biological and biomolecular processes. The understanding of solvation is an essential prerequisite for the quantitative description and analysis of biomolecular systems. This work presents a Lagrangian formulation of our differential geometry based solvation model. The Lagrangian representation of biomolecular surfaces has a few utilities/advantages. First, it provides an essential basis for biomolecular visualization, surface electrostatic potential map and visual perception of biomolecules. Additionally, it is consistent with the conventional setting of implicit solvent theories and thus, many existing theoretical algorithms and computational software packages can be directly employed. Finally, the Lagrangian representation does not need to resort to artificially enlarged van der Waals radii as often required by the Eulerian representation in solvation analysis. The main goal of the present work is to analyze the connection, similarity and difference between the Eulerian and Lagrangian formalisms of the solvation model. Such analysis is important to the understanding of the differential geometry based solvation model. The present model extends the scaled particle theory (SPT) of nonpolar solvation model with a solvent-solute interaction potential. The nonpolar solvation model is completed with a Poisson-Boltzmann (PB) theory based polar solvation model. The differential geometry theory of surfaces is employed to provide a natural description of solvent-solute interfaces. The minimization of the total free energy functional, which encompasses the polar and nonpolar contributions, leads to coupled potential driven geometric flow and Poisson-Boltzmann equations. Due to the development of singularities and nonsmooth manifolds in the Lagrangian representation, the resulting potential-driven geometric flow equation is embedded into the Eulerian representation for
Modeling individual effects in the Cormack-Jolly-Seber Model: A state-space formulation
Royle, J. Andrew
2008-01-01
In population and evolutionary biology, there exists considerable interest in individual heterogeneity in parameters of demographic models for open populations. However, flexible and practical solutions to the development of such models have proven to be elusive. In this article, I provide a state-space formulation of open population capture-recapture models with individual effects. The state-space formulation provides a generic and flexible framework for modeling and inference in models with individual effects, and it yields a practical means of estimation in these complex problems via contemporary methods of Markov chain Monte Carlo. A straightforward implementation can be achieved in the software package WinBUGS. I provide an analysis of a simple model with constant parameter detection and survival probability parameters. A second example is based on data from a 7-year study of European dippers, in which a model with year and individual effects is fitted.
NASA Astrophysics Data System (ADS)
Herman, J. D.; Reed, P. M.; Wagener, T.
2013-03-01
Lumped rainfall-runoff models are widely used for flow prediction, but a long-recognized need exists for diagnostic tools to determine whether the process-level behavior of a model aligns with the expectations inherent in its formulation. To this end, we develop a comprehensive exploration of dominant parameters in the Hymod, HBV, and Sacramento Soil Moisture Accounting (SAC-SMA) model structures. Model controls are isolated using time-varying Sobol' sensitivity analysis for twelve MOPEX watersheds in the eastern United States over a 10 year period. Sensitivity indices are visualized along gradients of observed precipitation and streamflow to identify key behavioral differences between the three models and to connect these back to the models' underlying assumptions. Results indicate that the models' dominant parameters strongly depend on time-varying hydroclimatic conditions. Parameters associated with surface processes such as evapotranspiration and runoff generally dominate under dry conditions, when high evaporative fluxes are required for accurate simulation. Parameters associated with routing processes typically dominate under high-flow conditions, when performance depends on the timing of flow events. The results highlight significant inter-model differences in performance controls, even in cases where the models share similar process formulations. The dominant parameters identified can be counterintuitive; even these simple models represent complex, nonlinear systems, and the links between formulation and behavior are difficult to discern a priori as complexity increases. Scrutinizing the links between model formulation and behavior becomes an important diagnostic approach, particularly in applications such as predictions under change where dominant model controls will shift under hydrologic extremes.
Higher Order Modeling In the BEM/FEM Hybrid Formulation
NASA Technical Reports Server (NTRS)
Fink, Patrick W.; Wilton, Don R.
2000-01-01
Hybrid formulations using low order curl-conforming bases to represent the total electric field within a finite element region and low order divergence-conforming bases to represent equivalent electric and magnetic currents on the boundary are well known. However, higher-order divergence and curl-conforming bases have been shown to provide significant benefits in convergence rates and accuracy when employed in strictly integral equation and strictly finite element formulations. In this paper, a hybrid electric field formulation employing higher order bases is presented. The paper addresses benefits and issues associated with using higher order divergence-and curl-conforming bases in the hybrid finite element/boundary element electric field formulation. The method of singularity subtraction may be used to compute the self terms of the boundary integral when the bases are of low order. But this method becomes laborious and requires great care when the divergence conforming bases are of higher order. In order to handle these singularities simply and accurately, a generalized Gaussian quadrature method is employed in which the expansion functions account for the singularity. In preliminary tests of the higher order hybrid formulation, the equivalent electric current induced by scattering of a plane wave from a square dielectric cylinder is examined. Accurate results are obtained using only a two-triangle mesh when the current basis is of order 4 or 5. Additional results are presented comparing the error obtained using higher order bases to that obtained using lower order bases when the number of unknowns is approximately equal. Also, convergence rates obtained with higher order bases are compared to those obtained with lower order bases for selected sample problems.
Urbanska, Aleksandra Malgorzata; Bhathena, Jasmine; Cherif, Sofiane; Prakash, Satya
2016-01-01
The development of intestinal polyps in an orthotopic colorectal mouse model, receiving a probiotic yogurt formulation containing microencapsulated live Lactobacillus acidophilus cells was investigated. The expression of various immunohistochemical markers namely CD8, Mac-1, Ki-67, and cleaved caspase-3, was evaluated. Results suggest that the probiotic formulation decreases overall intestinal inflammation. Mice receiving the probiotic formulation were found to develop almost two-fold fewer tumors in the small intestines. In the large intestine, however, there was no significant difference observed among polyp numbers. The formulation appears to have potential application in the prevention of various GI pathological conditions. PMID:25060720
An artificial intelligence approach to the formulation and maintenance of models
Raghunathan, S.
1990-01-01
The complexity and the fuzzy nature of modeling have resulted in an increased need for providing support to modelers in the modeling process. This study is aimed at developing a computer-based system that supports naive users in the formulation and maintenance of optimization models, specifically: linear programming, quadratic programming, and integer programming models, in a production planning and distribution domain. A conceptual model of the formulation process was developed through concurrent verbal protocol analysis of several experienced modelers solving a variety of textbook and case problems. This conceptual model formed the basis of the modeling support system. The system was implemented in common lisp and Flavors, an object oriented language, and runs on a VAX 8600 system. Several users employed the system in a laboratory setting to formulate models for two problems. an analysis of the resultant models indicates that the users are able to formulate correct models with the help of the system even though they are unable to formulate these models on their own.
Modified Eulerian-Lagrangian formulation for hydrodynamic modeling
NASA Astrophysics Data System (ADS)
Sorek, Shaul; Borisov, Vyacheslav
2012-04-01
We present the modified Eulerian-Lagrangian (MEL) formulation, based on non-divergent forms of partial differential balance equations, for simulating transport of extensive quantities in a porous medium. Hydrodynamic derivatives are written in terms of modified velocities for particles propagating phase and component quantities along their respective paths. The particles physically interpreted velocities also address the heterogeneity of the matrix and fluid properties. The MEL formulation is also implemented to parabolic Partial Differential Equations (PDE's) as these are shown to be interchangeable with equivalent PDE's having hyperbolic - parabolic characteristics, without violating the same physical concepts. We prove that the MEL schemes provide a convergent and monotone approximation also to PDE's with discontinuous coefficients. An extension to the Peclet number is presented that also accounts for advective dominant PDE's with no reference to the fluid velocity or even when this velocity is not introduced. In Sorek et al. [27], a mathematical analysis for a linear system of coupled PDE's and an example of nonlinear PDE's, proved that the finite difference MEL, unlike an Eulerian scheme, guaranties the absence of spurious oscillations. Currently, we present notions of monotone interpolation associated with the MEL particle tracking procedure and prove the convergence of the MEL schemes to the original balance equation also for discontinuous coefficients on the basis of difference schemes approximating PDE's. We provide numerical examples, also with highly random fields of permeabilities and/or dispersivities, suggesting that the MEL scheme produces resolutions that are more consistent with the physical phenomenon in comparison to the Eulerian and the Eulerian-Lagrangian (EL) schemes.
The formulations of the AMS/EPA Regulatory Model Improvement Committee's applied air dispersion model (AERMOD) as related to the characterization of the planetary boundary layer are described. This is the first in a series of three articles. Part II describes the formulation of...
Oh, S.H.; Bissett, E.J.; Battiston, P.A. )
1993-08-01
It has been widely recognized that a large fraction of CO and HC emissions occurs during the cold-start portion of the Federal Test Procedure (FTP) driving schedule. The previously-developed transient monolith model has been extended to describe the thermal response and conversion performance of an electrically heated monolith converter during warmup. This paper documents the necessary modifications in the model formulation and in the numerical solution methods to accommodate the more severe operating conditions encountered in heated converters. The validity of the heated converter model was tested by comparing model predictions with vehicle emission test data. Model predictions of converter-bed temperatures and converter-out mass emissions agree well with those measured during the cold-start portion of the vehicle emission tests, thus demonstrating the validity of the heated converter model developed here.
Spectrally formulated modeling of a cable-harnessed structure
NASA Astrophysics Data System (ADS)
Choi, Jiduck; Inman, Daniel J.
2014-07-01
To obtain predictive modeling of the spacecraft, we investigate the effects of adding cables to a simple structure with the goal of developing an understanding of the effects of cables interacting with a structure. In this paper, we present modeling of a cable-harnessed structure by means of the Spectral Element Method (SEM). A double beam model is used to emulate a cable-harnessed structure. SEM modeling can define the location and the number of connections between the two beams in a convenient fashion. The presented modeling is applied and compared with the conventional FEM. The modeling approach was compared and validated with experimental measurements. The validated modeling was implemented to investigate the effect of the number of connections and of the spring stiffness of interconnections. The results show that the proposed modeling can be used as an accurate and efficient solution methodology for a cable-harnessed structure.
Modeling of polymer networks for application to solid propellant formulating
NASA Technical Reports Server (NTRS)
Marsh, H. E.
1979-01-01
Methods for predicting the network structural characteristics formed by the curing of pourable elastomers were presented; as well as the logic which was applied in the development of mathematical models. A universal approach for modeling was developed and verified by comparison with other methods in application to a complex system. Several applications of network models to practical problems are described.
NASA Astrophysics Data System (ADS)
Ramadan, Omar
2012-05-01
Unified matrix-exponential finite difference time domain (ME-FDTD) formulations are presented for modeling linear multi-term electrically and magnetically dispersive materials. In the proposed formulations, Maxwell's curl equations and the related dispersive constitutive relations are cast into a set of first-order differential matrix system and the field's update equations can be extracted directly from the matrix-exponential approximation. The formulations have the advantage of simplicity as it allows modeling different linear dispersive materials in a systematic manner and also can be easily incorporated with the perfectly matched layer (PML) absorbing boundary conditions (ABCs) to model open region problems. Apart from its simplicity, it has been shown that the proposed formulations necessitate less storage requirements as compared with the well-know auxiliary differential equation FDTD (ADE-FDTD) scheme while maintaining the same accuracy performance.
Antileishmanial activity of a formulation of 2-n-propylquinoline by oral route in mice model.
Campos Vieira, N; Vacus, J; Fournet, A; Baudouin, R; Bories, C; Séon-Méniel, B; Figadère, B; Loiseau, P M
2011-11-01
2-n-propylquinoline is presently a drug-candidate for the treatment of visceral leishmaniosis in pre-clinical development. As this compound is in an oily state, it needs to be formulated and the objectives of this study are: to prepare a formulation; to demonstrate that the new salted formulation did not alter the activity of the active ingredient; and finally, that this activity was quite good compared to the reference oral drug, miltefosine. Therefore, a 2-n-propylquinoline formulation, as camphorsulfonic salt, was prepared and characterised. On the Leishmania donovani / Balb/c mice model, a treatment by oral route at 60 mmoles/kg/day for ten consecutive days with this formulation was compared to 2-n-propylquinoline alone and to miltefosine, the oral reference drug. The salt formulation did not alter the activity of the 2-n-propylquinoline. The formulation reduced the parasite burden of 76% compared to 89% for miltefosine (not significant). The characteristics of this formulation results in a suitable drugability of 2-n-propylquinoline for further studies. PMID:22091464
NASA Technical Reports Server (NTRS)
Saylor, Rick D.; Wolfe, Glenn M.; Meyers, Tilden P.; Hicks, Bruce B.
2014-01-01
The Multilayer Model (MLM) has been used for many years to infer dry deposition fluxes from measured trace species concentrations and standard meteorological measurements for national networks in the U.S., including the U.S. Environmental Protection Agency's Clean Air Status and Trends Network (CASTNet). MLM utilizes a resistance analogy to calculate deposition velocities appropriate for whole vegetative canopies, while employing a multilayer integration to account for vertically varying meteorology, canopy morphology and radiative transfer within the canopy. However, the MLM formulation, as it was originally presented and as it has been subsequently employed, contains a non-physical representation related to the leaf-level quasi-laminar boundary layer resistance that affects the calculation of the total canopy resistance. In this note, the non-physical representation of the canopy resistance as originally formulated in MLM is discussed and a revised, physically consistent, formulation is suggested as a replacement. The revised canopy resistance formulation reduces estimates of HNO3 deposition velocities by as much as 38% during mid-day as compared to values generated by the original formulation. Inferred deposition velocities for SO2 and O3 are not significantly altered by the change in formulation (less than 3%). Inferred deposition loadings of oxidized and total nitrogen from CASTNet data may be reduced by 10-20% and 5-10%, respectively, for the Eastern U. S. when employing the revised formulation of MLM as compared to the original formulation.
Practical Formulations of the Latent Growth Item Response Model
ERIC Educational Resources Information Center
McGuire, Leah Walker
2010-01-01
Growth modeling using longitudinal data seems to be a promising direction for improving the methodology associated with the accountability movement. Longitudinal modeling requires that the measurements of ability are comparable over time and on the same scale. One way to create the vertical scale is through concurrent estimation with…
Isotope-based Fluvial Organic Carbon (ISOFLOC) Model: Model formulation, sensitivity, and evaluation
NASA Astrophysics Data System (ADS)
Ford, William I.; Fox, James F.
2015-06-01
Watershed-scale carbon budgets remain poorly understood, in part due to inadequate simulation tools to assess in-stream carbon fate and transport. A new numerical model termed ISOtope-based FLuvial Organic Carbon (ISOFLOC) is formulated to simulate the fluvial organic carbon budget in watersheds where hydrologic, sediment transport, and biogeochemical processes are coupled to control benthic and transported carbon composition and flux. One ISOFLOC innovation is the formulation of new stable carbon isotope model subroutines that include isotope fractionation processes in order to estimate carbon isotope source, fate, and transport. A second innovation is the coupling of transfers between carbon pools, including algal particulate organic carbon, fine particulate and dissolved organic carbon, and particulate and dissolved inorganic carbon, to simulate the carbon cycle in a comprehensive manner beyond that of existing watershed water quality models. ISOFLOC was tested and verified in a low-gradient, agriculturally impacted stream. Results of a global sensitivity analysis suggested the isotope response variable had unique sensitivity to the coupled interaction between fluvial shear resistance of algal biomass and the concentration of dissolved inorganic carbon. Model calibration and validation suggested good agreement at event, seasonal, and annual timescales. Multiobjective uncertainty analysis suggested inclusion of the carbon stable isotope routine reduced uncertainty by 80% for algal particulate organic carbon flux estimates.
Theory of electrophoretic separations. I - Formulation of a mathematical model
NASA Technical Reports Server (NTRS)
Saville, D. A.; Palusinski, O. A.
1986-01-01
A generally applicable model of electrophoretic processes is presented. The model describes the chemical reactions, treating the chemical processes as reactions at equilibrium and accounting for convection, conservation, diffusion, and electromigration of individual species as well as the relation between charge and potential. Conservation relations are described and simplified, taking advantage of the speed of the chemical reactions as compared to the transport processes to adapt the model to the electrophoretic processes involving weak electrolytes. As an application example, isotachophoresis in a one-dimensional column is considered in detail.
A two-field modified Lagrangian formulation for robust simulations of extrinsic cohesive zone models
NASA Astrophysics Data System (ADS)
Cazes, F.; Coret, M.; Combescure, A.
2013-06-01
This paper presents the robust implementation of a cohesive zone model based on extrinsic cohesive laws (i.e. laws involving an infinite initial stiffness). To this end, a two-field Lagrangian weak formulation in which cohesive tractions are chosen as the field variables along the crack's path is presented. Unfortunately, this formulation cannot model the infinite compliance of the broken elements accurately, and no simple criterion can be defined to determine the loading-unloading change of state at the integration points of the cohesive elements. Therefore, a modified Lagrangian formulation using a fictitious cohesive traction instead of the classical cohesive traction as the field variable is proposed. Thanks to this change of variable, the cohesive law becomes an increasing function of the equivalent displacement jump, which eliminates the problems mentioned previously. The ability of the proposed formulations to simulate fracture accurately and without field oscillations is investigated through three numerical test examples.
Colbourn, E A; Roskilly, S J; Rowe, R C; York, P
2011-10-01
This study has investigated the utility and potential advantages of gene expression programming (GEP)--a new development in evolutionary computing for modelling data and automatically generating equations that describe the cause-and-effect relationships in a system--to four types of pharmaceutical formulation and compared the models with those generated by neural networks, a technique now widely used in the formulation development. Both methods were capable of discovering subtle and non-linear relationships within the data, with no requirement from the user to specify the functional forms that should be used. Although the neural networks rapidly developed models with higher values for the ANOVA R(2) these were black box and provided little insight into the key relationships. However, GEP, although significantly slower at developing models, generated relatively simple equations describing the relationships that could be interpreted directly. The results indicate that GEP can be considered an effective and efficient modelling technique for formulation data. PMID:21903163
Mathematical Formulation Requirements and Specifications for the Process Models
Steefel, C.; Moulton, D.; Pau, G.; Lipnikov, K.; Meza, J.; Lichtner, P.; Wolery, T.; Bacon, D.; Spycher, N.; Bell, J.; Moridis, G.; Yabusaki, S.; Sonnenthal, E.; Zyvoloski, G.; Andre, B.; Zheng, L.; Davis, J.
2010-11-01
The Advanced Simulation Capability for Environmental Management (ASCEM) is intended to be a state-of-the-art scientific tool and approach for understanding and predicting contaminant fate and transport in natural and engineered systems. The ASCEM program is aimed at addressing critical EM program needs to better understand and quantify flow and contaminant transport behavior in complex geological systems. It will also address the long-term performance of engineered components including cementitious materials in nuclear waste disposal facilities, in order to reduce uncertainties and risks associated with DOE EM's environmental cleanup and closure activities. Building upon national capabilities developed from decades of Research and Development in subsurface geosciences, computational and computer science, modeling and applied mathematics, and environmental remediation, the ASCEM initiative will develop an integrated, open-source, high-performance computer modeling system for multiphase, multicomponent, multiscale subsurface flow and contaminant transport. This integrated modeling system will incorporate capabilities for predicting releases from various waste forms, identifying exposure pathways and performing dose calculations, and conducting systematic uncertainty quantification. The ASCEM approach will be demonstrated on selected sites, and then applied to support the next generation of performance assessments of nuclear waste disposal and facility decommissioning across the EM complex. The Multi-Process High Performance Computing (HPC) Simulator is one of three thrust areas in ASCEM. The other two are the Platform and Integrated Toolsets (dubbed the Platform) and Site Applications. The primary objective of the HPC Simulator is to provide a flexible and extensible computational engine to simulate the coupled processes and flow scenarios described by the conceptual models developed using the ASCEM Platform. The graded and iterative approach to assessments naturally
Contingency contractor optimization. Phase 3, model description and formulation.
Gearhart, Jared Lee; Adair, Kristin Lynn; Jones, Katherine A.; Bandlow, Alisa; Durfee, Justin D.; Jones, Dean A.; Martin, Nathaniel; Detry, Richard Joseph; Nanco, Alan Stewart; Nozick, Linda Karen
2013-10-01
The goal of Phase 3 the OSD ATL Contingency Contractor Optimization (CCO) project is to create an engineering prototype of a tool for the contingency contractor element of total force planning during the Support for Strategic Analysis (SSA). An optimization model was developed to determine the optimal mix of military, Department of Defense (DoD) civilians, and contractors that accomplishes a set of user defined mission requirements at the lowest possible cost while honoring resource limitations and manpower use rules. An additional feature allows the model to understand the variability of the Total Force Mix when there is uncertainty in mission requirements.
Contingency contractor optimization. phase 3, model description and formulation.
Gearhart, Jared Lee; Adair, Kristin Lynn; Jones, Katherine A.; Bandlow, Alisa; Detry, Richard Joseph; Durfee, Justin D.; Jones, Dean A.; Martin, Nathaniel; Nanco, Alan Stewart; Nozick, Linda Karen
2013-06-01
The goal of Phase 3 the OSD ATL Contingency Contractor Optimization (CCO) project is to create an engineering prototype of a tool for the contingency contractor element of total force planning during the Support for Strategic Analysis (SSA). An optimization model was developed to determine the optimal mix of military, Department of Defense (DoD) civilians, and contractors that accomplishes a set of user defined mission requirements at the lowest possible cost while honoring resource limitations and manpower use rules. An additional feature allows the model to understand the variability of the Total Force Mix when there is uncertainty in mission requirements.
A variational formulation for time-dependent climate models
NASA Technical Reports Server (NTRS)
Smith, G. L.
1984-01-01
A variational principle for time dependent diffusion problems is presented and is demonstrated by applying it to simple seasonal climate models. Two cases are treated. The first, a North-Coakley-type model with constant properties, is used as a tutorial example for the application of the technique. For the second case, heat capacity and thermal conductivity are considered to be latitude dependent in order to treat the effects of land/ocean distribution on the seasonal temperature distribution over the earth. The variational equations are derived and approximate analytical solutions are developed which delineate the influences of the physical asymmetries of the hemispheres in producing an asymmetric annual cycle.
de Barros, João M S; Costabile, Adele; Charalampopoulos, Dimitrios; Khutoryanskiy, Vitaliy V; Edwards, Alexander D
2016-05-01
Gastrointestinal (GI) models that mimic physiological conditions in vitro are important tools for developing and optimizing biopharmaceutical formulations. Oral administration of live attenuated bacterial vaccines (LBV) can safely and effectively promote mucosal immunity but new formulations are required that provide controlled release of optimal numbers of viable bacterial cells, which must survive gastrointestinal transit overcoming various antimicrobial barriers. Here, we use a gastro-small intestine gut model of human GI conditions to study the survival and release kinetics of two oral LBV formulations: the licensed typhoid fever vaccine Vivotif comprising enteric coated capsules; and an experimental formulation of the model vaccine Salmonella Typhimurium SL3261 dried directly onto cast enteric polymer films and laminated to form a polymer film laminate (PFL). Neither formulation released significant numbers of viable cells when tested in the complete gastro-small intestine model. The poor performance in delivering viable cells could be attributed to a combination of acid and bile toxicity plus incomplete release of cells for Vivotif capsules, and to bile toxicity alone for PFL. To achieve effective protection from intestinal bile in addition to effective acid resistance, bile adsorbent resins were incorporated into the PFL to produce a new formulation, termed BR-PFL. Efficient and complete release of 4.4×10(7) live cells per dose was achieved from BR-PFL at distal intestinal pH, with release kinetics controlled by the composition of the enteric polymer film, and no loss in viability observed in any stage of the GI model. Use of this in vitro GI model thereby allowed rational design of an oral LBV formulation to maximize viable cell release. PMID:26969261
Formulation of Moist Dynamics and Physics for Future Climate Models
Celal S. Konor and Akio Arakwa
2008-04-30
In this project, one of our goals is to develop atmospheric models, in which innovative ideas on improving the quality of moisture predictions can be tested. Our other goal is to develop an explicit time integration scheme based on the multi-point differencing that does the same job as an implicit trapezoidal scheme but uses information only from limited number of grid points.
Formulation and Testing of a Novel River Nitrification Model
The nitrification process in many riverwater quality models has been approximated by a simple first order dependency on the water column ammonia concentration, while the benthic contribution has routinely been neglected. In this study a mathematical framework was developed for se...
White, Robin R; Capper, Judith L
2014-03-01
The objective of this study was to use a precision nutrition model to simulate the relationship between diet formulation frequency and dairy cattle performance across various climates. Agricultural Modeling and Training Systems (AMTS) CattlePro diet-balancing software (Cornell Research Foundation, Ithaca, NY) was used to compare 3 diet formulation frequencies (weekly, monthly, or seasonal) and 3 levels of climate variability (hot, cold, or variable). Predicted daily milk yield (MY), metabolizable energy (ME) balance, and dry matter intake (DMI) were recorded for each frequency-variability combination. Economic analysis was conducted to calculate the predicted revenue over feed and labor costs. Diet formulation frequency affected ME balance and MY but did not affect DMI. Climate variability affected ME balance and DMI but not MY. The interaction between climate variability and formulation frequency did not affect ME balance, MY, or DMI. Formulating diets more frequently increased MY, DMI, and ME balance. Economic analysis showed that formulating diets weekly rather than seasonally could improve returns over variable costs by $25,000 per year for a moderate-sized (300-cow) operation. To achieve this increase in returns, an entire feeding system margin of error of <1% was required. Formulating monthly, rather than seasonally, may be a more feasible alternative as this requires a margin of error of only 2.5% for the entire feeding system. Feeding systems with a low margin of error must be developed to better take advantage of the benefits of precision nutrition. PMID:24393175
Industrial processing of complex fluids: Formulation and modeling
Scovel, J.C.; Bleasdale, S.; Forest, G.M.; Bechtel, S.
1997-08-01
The production of many important commercial materials involves the evolution of a complex fluid through a cooling phase into a hardened product. Textile fibers, high-strength fibers(KEVLAR, VECTRAN), plastics, chopped-fiber compounds, and fiber optical cable are such materials. Industry desires to replace experiments with on-line, real time models of these processes. Solutions to the problems are not just a matter of technology transfer, but require a fundamental description and simulation of the processes. Goals of the project are to develop models that can be used to optimize macroscopic properties of the solid product, to identify sources of undesirable defects, and to seek boundary-temperature and flow-and-material controls to optimize desired properties.
Sublethal toxicant effects with dynamic energy budget theory: model formulation.
Muller, Erik B; Nisbet, Roger M; Berkley, Heather A
2010-01-01
We develop and test a general modeling framework to describe the sublethal effects of pollutants by adding toxicity modules to an established dynamic energy budget (DEB) model. The DEB model describes the rates of energy acquisition and expenditure by individual organisms; the toxicity modules describe how toxicants affect these rates by changing the value of one or more DEB parameters, notably the parameters quantifying the rates of feeding and maintenance. We investigate four toxicity modules that assume: (1) effects on feeding only; (2) effects on maintenance only; (3) effects on feeding and maintenance with similar values for the toxicity parameters; and (4) effects on feeding and maintenance with different values for the toxicity parameters. We test the toxicity modules by fitting each to published data on feeding, respiration, growth and reproduction. Among the pollutants tested are metals (mercury and copper) and various organic compounds (chlorophenols, toluene, polycyclic aromatic hydrocarbons, tetradifon and pyridine); organisms include mussels, oysters, earthworms, water fleas and zebrafish. In most cases, the data sets could be adequately described with any of the toxicity modules, and no single module gave superior fits to all data sets. We therefore propose that for many applications, it is reasonable to use the most general and parameter sparse module, i.e. module 3 that assumes similar effects on feeding and maintenance, as a default. For one example (water fleas), we use parameter estimates to calculate the impact of food availability and toxicant levels on the long term population growth rate. PMID:19633955
Schick, Robert S; Kraus, Scott D; Rolland, Rosalind M; Knowlton, Amy R; Hamilton, Philip K; Pettis, Heather M; Thomas, Len; Harwood, John; Clark, James S
2016-01-01
Right whales are vulnerable to many sources of anthropogenic disturbance including ship strikes, entanglement with fishing gear, and anthropogenic noise. The effect of these factors on individual health is unclear. A statistical model using photographic evidence of health was recently built to infer the true or hidden health of individual right whales. However, two important prior assumptions about the role of missing data and unexplained variance on the estimates were not previously assessed. Here we tested these factors by varying prior assumptions and model formulation. We found sensitivity to each assumption and used the output to make guidelines on future model formulation. PMID:26611058
Modeling surface tension using a ghost fluid technique within a volume of fluid formulation
Francois, M. M.; Kothe, D. B.; Cummins, S. J.
2004-01-01
Ghost fluid methods (GFM) are a viable approach for imposing sharp boundary conditions on interfaces that are arbitrarily embedded within the computational mesh. All GFM to date are formulated with an interface distance function that resides within a level-set (LS) framework. Recently we proposed a technique for reconstructing distance functions from volume fractions. This technique enables the exploitation of GFM within a volume of fluid formulation for modeling an interfacial phenomenon like surface tension. Combining GFM with a volume of fluid (VOF) formulation is attractive because of the VOF method's superior mass conservation and because of the ability of GFM to maintain sharp jump conditions. The continuum surface tension force (CSF) method, however, has the propensity to produce smooth jump. In the following, the combined VOF-GFM and more classical VOF-CSF formulations are compared and contrasted. Static and dynamic numerical results are used to illustrate our findings and support our claims.
NASA Astrophysics Data System (ADS)
Treutenaere, S.; Lauro, F.; Bennani, B.; Matsumoto, T.; Mottola, E.
2015-09-01
The use of fabric reinforced polymers in the automotive industry is growing significantly. The high specific stiffness and strength, the ease of shaping as well as the great impact performance of these materials widely encourage their diffusion. The present model increases the predictability of explicit finite element analysis and push the boundaries of the ongoing phenomenological model. Carbon fibre composites made up various preforms were tested by applying different mechanical load up to dynamic loading. This experimental campaign highlighted the physical mechanisms affecting the initial mechanical properties, namely intra- and interlaminar matrix damage, viscoelasticty and fibre failure. The intralaminar behaviour model is based on the explicit formulation of the matrix damage model developed by the ONERA as the given damage formulation correlates with the experimental observation. Coupling with a Maxwell-Wiechert model, the viscoelasticity is included without losing the direct explicit formulation. Additionally, the model is formulated under a total Lagrangian scheme in order to maintain consistency for finite strain. Thus, the material frame-indifference as well as anisotropy are ensured. This allows reorientation of fibres to be taken into account particularly for in-plane shear loading. Moreover, fall within the framework of the total Lagrangian scheme greatly makes the parameter identification easier, as based on the initial configuration. This intralaminar model thus relies upon a physical description of the behaviour of fabric composites and the numerical simulations show a good correlation with the experimental results.
Statistical modelling of the formulation variables in non-viral gene delivery systems.
Birchall, J C; Waterworth, C A; Luscombe, C; Parkins, D A; Gumbleton, M
2001-06-01
Traditionally, optimisation of a gene delivery formulation utilises a study design that involves altering only one formulation variable at any one time whilst keeping the other variables constant. As gene delivery formulations become more complex, e.g. to include multiple cellular and sub-cellular targeting elements, there will be an increasing requirement to generate and analyse data more efficiently and allow examination of the interaction between variables. This study aims to demonstrate the utility of multifactorial design, specifically a Central Composite Design, in modelling the responses size, zeta potential and in vitro transfection efficiency of some prototypic non-viral gene delivery vectors. i.e. cationic liposome-pDNA complexes, and extending the application of the design strategy to more complex vectors, i.e. tri-component lipid:polycation:DNA (LPD). The modelled predictions of how the above responses change as a function of formulation show consistency with an extensive literature base of data obtained using more traditional approaches, and highlight the robustness and utility of the Central Composite Design in examining key formulation variables in non-viral gene delivery systems. The approach should be further developed to maximise the predictive impact of data across the full range of pharmaceutical sciences. PMID:11697203
NASA Technical Reports Server (NTRS)
Song, Y.; Wright, D.
1998-01-01
A formulation of the pressure gradient force for use in models with topography-following coordinates is proposed and diagnostically analyzed by Song. We investigate numerical consistency with respect to global energy conservation, depth-integrated momentum changes, and the represent of the bottom pressure torque.
Variational formulation for Black-Scholes equations in stochastic volatility models
NASA Astrophysics Data System (ADS)
Gyulov, Tihomir B.; Valkov, Radoslav L.
2012-11-01
In this note we prove existence and uniqueness of weak solutions to a boundary value problem arising from stochastic volatility models in financial mathematics. Our settings are variational in weighted Sobolev spaces. Nevertheless, as it will become apparent our variational formulation agrees well with the stochastic part of the problem.
Droppo, James G.
2006-07-01
The Department of Homeland Security and others rely on results from atmospheric dispersion models for threat evaluation, event management, and post-event analyses. The ability to simulate dry deposition rates is a crucial part of our emergency preparedness capabilities. Deposited materials pose potential hazards from radioactive shine, inhalation, and ingestion pathways. A reliable characterization of these potential exposures is critical for management and mitigation of these hazards. A review of the current status of dry deposition formulations used in these atmospheric dispersion models was conducted. The formulations for dry deposition of particulate materials from am event such as a radiological attack involving a Radiological Detonation Device (RDD) is considered. The results of this effort are applicable to current emergency preparedness capabilities such as are deployed in the Interagency Modeling and Atmospheric Assessment Center (IMAAC), other similar national/regional emergency response systems, and standalone emergency response models. The review concludes that dry deposition formulations need to consider the full range of particle sizes including: 1) the accumulation mode range (0.1 to 1 micron diameter) and its minimum in deposition velocity, 2) smaller particles (less than .01 micron diameter) deposited mainly by molecular diffusion, 3) 10 to 50 micron diameter particles deposited mainly by impaction and gravitational settling, and 4) larger particles (greater than 100 micron diameter) deposited mainly by gravitational settling. The effects of the local turbulence intensity, particle characteristics, and surface element properties must also be addressed in the formulations. Specific areas for improvements in the dry deposition formulations are 1) capability of simulating near-field dry deposition patterns, 2) capability of addressing the full range of potential particle properties, 3) incorporation of particle surface retention/rebound processes, and
Compositional Models of Glass/Melt Properties and their Use for Glass Formulation
Vienna, John D.; USA, Richland Washington
2014-12-18
Nuclear waste glasses must simultaneously meet a number of criteria related to their processability, product quality, and cost factors. The properties that must be controlled in glass formulation and waste vitrification plant operation tend to vary smoothly with composition allowing for glass property-composition models to be developed and used. Models have been fit to the key glass properties. The properties are transformed so that simple functions of composition (e.g., linear, polynomial, or component ratios) can be used as model forms. The model forms are fit to experimental data designed statistically to efficiently cover the composition space of interest. Examples of these models are found in literature. The glass property-composition models, their uncertainty definitions, property constraints, and optimality criteria are combined to formulate optimal glass compositions, control composition in vitrification plants, and to qualify waste glasses for disposal. An overview of current glass property-composition modeling techniques is summarized in this paper along with an example of how those models are applied to glass formulation and product qualification at the planned Hanford high-level waste vitrification plant.
Compositional Models of Glass/Melt Properties and their Use for Glass Formulation
Vienna, John D.; USA, Richland Washington
2014-12-18
Nuclear waste glasses must simultaneously meet a number of criteria related to their processability, product quality, and cost factors. The properties that must be controlled in glass formulation and waste vitrification plant operation tend to vary smoothly with composition allowing for glass property-composition models to be developed and used. Models have been fit to the key glass properties. The properties are transformed so that simple functions of composition (e.g., linear, polynomial, or component ratios) can be used as model forms. The model forms are fit to experimental data designed statistically to efficiently cover the composition space of interest. Examples ofmore » these models are found in literature. The glass property-composition models, their uncertainty definitions, property constraints, and optimality criteria are combined to formulate optimal glass compositions, control composition in vitrification plants, and to qualify waste glasses for disposal. An overview of current glass property-composition modeling techniques is summarized in this paper along with an example of how those models are applied to glass formulation and product qualification at the planned Hanford high-level waste vitrification plant.« less
Model for inter-epithelial flow of an anti-HIV microbicidal drug delivery formulation
NASA Astrophysics Data System (ADS)
Szeri, Andrew; Katz, David
2005-11-01
We consider the spreading characteristics of a Newtonian and a non-Newtonian fluid between compliant surfaces. This is a model for inter-epithelial flow of an anti-HIV microbicidal drug delivery formulation. Squeezing and gravity drive the flow. Owing to the large shear viscosity and narrow flow domain with compliant walls, the problem is an application of elastohydrodynamic lubrication theory. Dimensional analysis and numerical simulation reveal the influence of shear viscosity, wall compliance, longitudinal pressure gradient, formulation volume and channel dimensions on the area coated by the formulation. This area is a function of: (i) a dimensionless parameter which measures the relative importance of gravity-driven and compliance-driven flows, and (ii) time made dimensionless by the compliance and the shear viscosity. The coated area is of central importance in the functioning and evaluation of candidate microbicide delivery systems.
Aphrodisiac activity of polyherbal formulation in experimental models on male rats
Sahoo, Himanshu Bhusan; Nandy, Subhangkar; Senapati, Aswini Kumar; Sarangi, Sarada Prasad; Sahoo, Saroj Kumar
2014-01-01
Objective: To investigate the aphrodisiac potential of polyherbal formulations prepared from different parts of Tribulus terrestris, Curculigo orchioides, Allium tuberosum, Cucurbita pepo, Elephant creeper, Mucuna pruriens, and Terminalia catappa in Albino rats in specified ratio as suspension. Materials and Methods: The different concentrations of prepared polyherbal formulations i.e. 150, 300, and 600 mg/kg and sildenafil citrate as standard (5 mg/kg) and vehicle (control) were administered orally to rats (n = 6 animals per group) for 3 weeks. Mating behavior parameters in male rats was monitored in first week and third week week of treatment pairing with receptive females. After termination of drug treatment, the mating performance, hormonal analysis, sperm count, and testes-body weight ratio were also evaluated. Results: The polyherbal formulation showed a significant increase in mating behavior as well as mating performance, serum hormonal levels, sperm count, and testes-body weight ratio with dose-dependent relationship as compared to vehicle control. But the dose of 600 mg/kg of polyherbal formulation assumes closer resemblance of above parameters with the standard used. Conclusion: The results of the study strongly suggest that the polyherbal formulations have a good aphrodisiac activity on rats in the above experimental models, which may be an alternative weapon for various sexual dysfunctions in future. PMID:24761115
NASA Astrophysics Data System (ADS)
Garner, G. G.; Reed, P. M.; Keller, K.
2014-12-01
Integrated assessment models (IAMs) are often used with the intent to aid in climate change decisionmaking. Numerous studies have analyzed the effects of parametric and/or structural uncertainties in IAMs, but uncertainties regarding the problem formulation are often overlooked. Here we use the Dynamic Integrated model of Climate and the Economy (DICE) to analyze the effects of uncertainty surrounding the problem formulation. The standard DICE model adopts a single objective to maximize a weighted sum of utilities of per-capita consumption. Decisionmakers, however, may be concerned with a broader range of values and preferences that are not captured by this a priori definition of utility. We reformulate the problem by introducing three additional objectives that represent values such as (i) reliably limiting global average warming to two degrees Celsius and minimizing both (ii) the costs of abatement and (iii) the damages due to climate change. We derive a set of Pareto-optimal solutions over which decisionmakers can trade-off and assess performance criteria a posteriori. We illustrate the potential for myopia in the traditional problem formulation and discuss the capability of this multiobjective formulation to provide decision support.
NASA Astrophysics Data System (ADS)
Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob
2016-04-01
The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.
NASA Astrophysics Data System (ADS)
Nagel, T.; Böttcher, N.; Görke, U. J.; Kolditz, O.
2014-12-01
The design process of geotechnical installations includes the application of numerical simulation tools for safety assessment, dimensioning and long term effectiveness estimations. Underground salt caverns can be used for the storage of natural gas, hydrogen, oil, waste or compressed air. For their design one has to take into account fluctuating internal pressures due to different levels of filling, the stresses imposed by the surrounding rock mass, irregular geometries and possibly heterogeneous material properties [3] in order to estimate long term cavern convergence as well as locally critical wall stresses. Constitutive models applied to rock salt are usually viscoplastic in nature and most often based on a Burgers-type rheological model extended by non-linear viscosity functions and/or plastic friction elements. Besides plastic dilatation, healing and damage are sometimes accounted for as well [2]. The scales of the geotechnical system to be simulated and the laboratory tests from which material parameters are determined are vastly different. The most common material testing modalities to determine material parameters in geoengineering are the uniaxial and the triaxial compression tests. Some constitutive formulations in widespread use are formulated based on equivalent rather than tensorial quantities valid under these specific test conditions and are subsequently applied to heterogeneous underground systems and complex 3D load cases. We show here that this procedure is inappropriate and can lead to erroneous results. We further propose alternative formulations of the constitutive models in question that restore their validity under arbitrary loading conditions. For an efficient numerical simulation, the discussed constitutive models are integrated locally with a Newton-Raphson algorithm that directly provides the algorithmically consistent tangent matrix for the global Newton iteration of the displacement based finite element formulation. Finally, the finite
Limbert, Georges
2011-11-01
Characterising and modelling the mechanical behaviour of biological soft tissues is an essential step in the development of predictive computational models to assist research for a wide range of applications in medicine, biology, tissue engineering, pharmaceutics, consumer goods, cosmetics, transport or military. It is therefore critical to develop constitutive models that can capture particular rheological mechanisms operating at specific length scales so that these models are adapted for their intended applications. Here, a novel mesoscopically-based decoupled invariant-based continuum constitutive framework for transversely isotropic and orthotropic biological soft tissues is developed. A notable feature of the formulation is the full decoupling of shear interactions. The constitutive model is based on a combination of the framework proposed by Lu and Zhang [Lu, J., Zhang, L., 2005. Physically motivated invariant formulation for transversely isotropic hyperelasticity. International Journal of Solids and Structures 42, 6015-6031] and the entropic mechanics of tropocollagen molecules and collagen assemblies. One of the key aspects of the formulation is to use physically-based nanoscopic quantities that could be extracted from experiments and/or atomistic/molecular dynamics simulations to inform the macroscopic constitutive behaviour. This effectively couples the material properties at different levels of the multi-scale hierarchical structure of collagenous tissues. The orthotropic hyperelastic model was shown to reproduce very well the experimental multi-axial properties of rabbit skin. A new insight into the shear response of a skin sample subjected to a simulated indentation test was obtained using numerical direct sensitivity analyses. PMID:22098866
Formulation of human-structure interaction system models for vertical vibration
NASA Astrophysics Data System (ADS)
Caprani, Colin C.; Ahmadi, Ehsan
2016-09-01
In this paper, human-structure interaction system models for vibration in the vertical direction are considered. This work assembles various moving load models from the literature and proposes extension of the single pedestrian to a crowd of pedestrians for the FE formulation for crowd-structure interaction systems. The walking pedestrian vertical force is represented as a general time-dependent force, and the pedestrian is in turn modelled as moving force, moving mass, and moving spring-mass-damper. The arbitrary beam structure is modelled using either a formulation in modal coordinates or finite elements. In each case, the human-structure interaction (HSI) system is first formulated for a single walking pedestrian and then extended to consider a crowd of pedestrians. Finally, example applications for single pedestrian and crowd loading scenarios are examined. It is shown how the models can be used to quantify the interaction between the crowd and bridge structure. This work should find use for the evaluation of existing and new footbridges.
Bammann, Douglas J.; Johnson, G. C. (University of California, Berkeley, CA); Marin, Esteban B.; Regueiro, Richard A.
2006-01-01
In this report we present the formulation of the physically-based Evolving Microstructural Model of Inelasticity (EMMI) . The specific version of the model treated here describes the plasticity and isotropic damage of metals as being currently applied to model the ductile failure process in structural components of the W80 program . The formulation of the EMMI constitutive equations is framed in the context of the large deformation kinematics of solids and the thermodynamics of internal state variables . This formulation is focused first on developing the plasticity equations in both the relaxed (unloaded) and current configurations. The equations in the current configuration, expressed in non-dimensional form, are used to devise the identification procedure for the plasticity parameters. The model is then extended to include a porosity-based isotropic damage state variable to describe the progressive deterioration of the strength and mechanical properties of metals induced by deformation . The numerical treatment of these coupled plasticity-damage constitutive equations is explained in detail. A number of examples are solved to validate the numerical implementation of the model.
A new pressure formulation for gas-compressibility dampening in bubble dynamics models.
Gadi Man, Yezaz Ahmed; Trujillo, Francisco J
2016-09-01
We formulated a pressure equation for bubbles performing nonlinear radial oscillations under ultrasonic high pressure amplitudes. The proposed equation corrects the gas pressure at the gas-liquid interface on inertial bubbles. This pressure formulation, expressed in terms of gas-Mach number, accounts for dampening due to gas compressibility during the violent collapse of cavitation bubbles and during subsequent rebounds. We refer to this as inhomogeneous pressure, where the gas pressure at the gas-liquid interface can differ to the pressure at the centre of the bubble, in contrast to homogenous pressure formulations that consider that pressure inside the bubble is spatially uniform from the wall to the centre. The pressure correction was applied to two bubble dynamic models: the incompressible Rayleigh-Plesset equation and the compressible Keller and Miksis equation. This improved the predictions of the nonlinear radial motion of the bubble vs time obtained with both models. Those simulations were also compared with other bubble dynamics models that account for liquid and gas compressibility effects. It was found that our corrected models are in closer agreement with experimental data than alternative models. It was concluded that the Rayleigh-Plesset family of equations improve accuracy by using our proposed pressure correction. PMID:27150768
Coradeschi, Francesco; De Curtis, Stefania; Dominici, Daniele
2010-07-01
We consider the continuum limit of a moose model corresponding to a generalization to N sites of the degenerate BESS model. The five-dimensional formulation emerging in this limit is a realization of a RS1 type model with SU(2){sub L} x SU(2){sub R} in the bulk, broken by boundary conditions and a vacuum expectation value on the infrared brane. A low-energy effective Lagrangian is derived by means of the holographic technique and corresponding bounds on the model parameters are obtained.
NASA Astrophysics Data System (ADS)
Coradeschi, Francesco; de Curtis, Stefania; Dominici, Daniele
2010-07-01
We consider the continuum limit of a moose model corresponding to a generalization to N sites of the degenerate BESS model. The five-dimensional formulation emerging in this limit is a realization of a RS1 type model with SU(2)L⊗SU(2)R in the bulk, broken by boundary conditions and a vacuum expectation value on the infrared brane. A low-energy effective Lagrangian is derived by means of the holographic technique and corresponding bounds on the model parameters are obtained.
Continuum Level Formulation and Implementation of a Multi-scale Model for Vanadium
Lawrence Livermore National Laboratory
2009-08-17
A multi-scale approach is used to construct a continuum strength model for vanadium. The model is formulated assuming plastic deformation by dislocation motion and strain hardening due to dislocation interactions. Dislocation density is adopted as the state variable in the model. Information from molecular statics, molecular dynamics and dislocation dynamics simulations is combined to create kinetic relations for dislocation motion, strain hardening relations and evolution equations for the dislocation density. Implicit time integration of the constitutive equations is described in the context of implementation in a finite element code. Results are provided illustrating the strain, strain rate, temperature and pressure dependence of the constitutive model.
NASA Astrophysics Data System (ADS)
Moghimi, Saeed; Klingbeil, Knut; Gräwe, Ulf; Burchard, Hans
2013-10-01
In this study a model system consisting of the three-dimensional General Estuarine Transport Model (GETM) and the third generation wind wave model SWAN was developed. Both models were coupled in two-way mode. The effects of waves were included into the ocean model by implementing the depth-dependent Radiation stress formulation (RS) of Mellor (2011a) and the Vortex force formulation (VF) presented by Bennis et al. (2011). Thus, the developed model system offers a direct comparison of these two formulations. The enhancement of the vertical eddy viscosity due to the energy transfer by white capping and breaking waves was taken into account by means of injecting turbulent kinetic energy at the surface. Wave-current interaction inside the bottom boundary layer was considered as well. The implementation of both wave-averaged formulations was validated against three flume experiments. One of these experiments with long period surface waves (swell), had not been evaluated before. The validation showed the capability of the model system to reproduce the three-dimensional interaction of waves and currents. For the flume test cases the wave-induced water level changes (wave set-up and set-down) and the corresponding depth-integrated wave-averaged velocities were similar for RS and VF. Both formulations produced comparable velocity profiles for short period waves. However, for large period waves, VF overestimated the wave set-down near the main breaking points and RS showed artificial offshore-directed transport at the surface where wave shoaling was taking place. Finally the validated model system was applied to a realistic barred beach scenario. For RS and VF the resulting velocity profiles were similar after being significantly improved by a roller evolution method. Both wave-averaged formulations generally provided similar results, but some shortcomings were revealed. Although VF partly showed significant deviations from the measurements, its results were still physically
Polster, Christopher S; Wu, Sy-Juen; Gueorguieva, Ivelina; Sperry, David C
2015-04-01
An artificial stomach duodenum (ASD) model has been used to demonstrate the performance difference between two formulations of LY2300559, a low-solubility acidic developmental drug. The two formulations investigated were a conventional high-shear wet granulation (HSWG) formulation and a solid dispersion formulation. A pharmacokinetic study in humans demonstrated the enhanced performance of the solid dispersion formulation relative to the HSWG formulation. The Cmax and AUC of the solid dispersion was 2.6 and 1.9 times greater, respectively, compared to the HSWG formulation. In the ASD, the solid dispersion formulation performance was characterized by three main phases: (1) rapid release in the stomach, creating a supersaturated concentration of drug, (2) precipitation in the stomach, and (3) rapid redissolution of the precipitate in the duodenum to concentration levels that are supersaturated relative to crystalline drug. A series of complementary experiments were employed to describe this performance behavior mechanistically. Imaging experiments with a pH indicating dye showed that local pH gradients from meglumine in the solid dispersion formulation were responsible for creating a high initial supersaturation concentration in the stomach. Upon dissipation of meglumine, the drug precipitated in the stomach as an amorphous solid. Because the precipitated drug is in an amorphous form, it can then rapidly redissolve as it transits to the more neutral environment of the duodenum. This unexpected sequence of physical state changes gives a mechanistic explanation for the enhanced in vivo performance of the solid dispersion formulation relative to the HSWG formulation. PMID:25723790
Chiral formulation for hyperKähler sigma-models on cotangent bundles of symmetric spaces
NASA Astrophysics Data System (ADS)
Kuzenko, Sergei M.; Novak, Joseph
2008-12-01
Starting with the projective-superspace off-shell formulation for four-dimensional Script N = 2 supersymmetric sigma-models on cotangent bundles of arbitrary Hermitian symmetric spaces, their on-shell description in terms of Script N = 1 chiral superfields is developed. In particular, we derive a universal representation for the hyperkähler potential in terms of the curvature of the symmetric base space. Within the tangent-bundle formulation for such sigma-models, completed recently in arXiv:0709.2633 and realized in terms of Script N = 1 chiral and complex linear superfields, we give a new universal formula for the superspace Lagrangian. A closed form expression is also derived for the Kähler potential of an arbitrary Hermitian symmetric space in Kähler normal coordinates.
Reduced order modeling of the Newton formulation of MODFLOW to solve unconfined groundwater flow
NASA Astrophysics Data System (ADS)
Boyce, Scott E.; Nishikawa, Tracy; Yeh, William W.-G.
2015-09-01
Projection-based model reduction techniques have been shown to be very effective for reducing the computational burden of high-dimensional groundwater simulations, but only applied to confined groundwater flow. A new methodology is proposed that reduces the dimension of a discretized, transient, unconfined groundwater-flow model. This unconfined model reduction technique is based on Galerkin projection and the Newton formulation of MODFLOW. The method is implemented following the standard package design and code structure that MODFLOW employs for all its features. When the package is invoked within MODFLOW it can collect snapshots, produce a basis, construct the reduced model and propagate the reduced model forward in time. The new formulation accurately represents the water-table surface under a variety of nonlinear settings, such as intraborehole flow from a Multi-Node Well. The unconfined model reduction is applied to four test cases to illustrate its flexibility in handling nonlinear features. Several test cases are discussed to demonstrate the unconfined model reduction applicability. The final test case applies the new model reduction methodology to a scoping MODFLOW model of Santa Barbara, CA composed of 113,578 cells, which requires solving 113,578 equations per time step, and reduces it to 127 equations.
Mathematical Modelling of Force Convection in a Two-Phase Thermosyphon in Conjugate Formulation
NASA Astrophysics Data System (ADS)
Nurpeiis, Atlant; Nee, Alexander
2016-02-01
A nonlinear non-stationary problem of the conductive-convective heat transfer is addressed (under forced convection conditions) in the thermosyphon of rectangular cross-section. The thermal energy supply is carried out through the lower horizontal border. The mathematical model is formulated in dimensionless variables of "velocity vorticity vector - current function - temperature". The current and temperature distribution lines are obtained, illustrating the effect of the Reynolds number on the thermodynamic structures formation in the analyzed object.
NASA Technical Reports Server (NTRS)
Torian, J. G.
1977-01-01
Consumables models required for the mission planning and scheduling function are formulated. The relation of the models to prelaunch, onboard, ground support, and postmission functions for the space transportation systems is established. Analytical models consisting of an orbiter planning processor with consumables data base is developed. A method of recognizing potential constraint violations in both the planning and flight operations functions, and a flight data file storage/retrieval of information over an extended period which interfaces with a flight operations processor for monitoring of the actual flights is presented.
Koster, R.D.; Milly, P.C.D.
1997-01-01
The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) has shown that different land surface models (LSMs) driven by the same meteorological forcing can produce markedly different surface energy and water budgets, even when certain critical aspects of the LSMs (vegetation cover, albedo, turbulent drag coefficient, and snowcover) are carefully controlled. To help explain these differences, the authors devised a monthly water balance model that successfully reproduces the annual and seasonal water balances of the different PILPS schemes. Analysis of this model leads to the identification of two quantities that characterize an LSM's formulation of soil water balance dynamics: 1) the efficiency of the soil's evaporation sink integrated over the active soil moisture range, and 2) the fraction of this range over which runoff is generated. Regardless of the LSM's complexity, the combination of these two derived parameters with rates of interception loss, potential evaporation, and precipitation provides a reasonable estimate for the LSM's simulated annual water balance. The two derived parameters shed light on how evaporation and runoff formulations interact in an LSM, and the analysis as a whole underscores the need for compatibility in these formulations.
NASA Technical Reports Server (NTRS)
Koster, Rindal D.; Milly, P. C. D.
1997-01-01
The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) has shown that different land surface models (LSMS) driven by the same meteorological forcing can produce markedly different surface energy and water budgets, even when certain critical aspects of the LSMs (vegetation cover, albedo, turbulent drag coefficient, and snow cover) are carefully controlled. To help explain these differences, the authors devised a monthly water balance model that successfully reproduces the annual and seasonal water balances of the different PILPS schemes. Analysis of this model leads to the identification of two quantities that characterize an LSM's formulation of soil water balance dynamics: (1) the efficiency of the soil's evaporation sink integrated over the active soil moisture range, and (2) the fraction of this range over which runoff is generated. Regardless of the LSM's complexity, the combination of these two derived parameters with rates of interception loss, potential evaporation, and precipitation provides a reasonable estimate for the LSM's simulated annual water balance. The two derived parameters shed light on how evaporation and runoff formulations interact in an LSM, and the analysis as a whole underscores the need for compatibility in these formulations.
NASA Astrophysics Data System (ADS)
Hussain, Tariq; Liu, Yan; Huang, Fenglei; Duan, Zhuoping
2016-01-01
The change in shock sensitivity of explosives having various explosive grain sizes is discussed. Along with other parameters, explosive grain size is one of the key parameters controlling the macroscopic behavior of shocked pressed explosives. Ignition and growth reactive flow modeling is performed for the shock initiation experiments carried out by using the in situ manganin piezoresistive pressure gauge technique to investigate the influences of the octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) particle size on the shock initiation and the subsequent detonation growth process for the three explosive formulations of pressed PBXC03 (87% HMX, 7% 1,3,5-trichloro-2,4,6-trinitrobenzene (TATB), 6% Viton by weight). All of the formulation studied had the same density but different explosive grain sizes. A set of ignition and growth parameters was obtained for all three formulations. Only the coefficient G1 of the first growth term in the reaction rate equation was varied with the grain size; all other parameters were kept the same for all formulations. It was found that G1 decreases almost linearly with HMX particle size for PBXC03. However, the equation of state (EOS) for solid explosive had to be adjusted to fit the experimental data. Both experimental and numerical simulation results show that the shock sensitivity of PBXC03 decreases with increasing HMX particle size for the sustained pressure pulses (around 4 GPa) as obtained in the experiment. This result is in accordance with the results reported elsewhere in literature. For future work, a better approach may be to find standard solid Grüneisen EOS and product Jones-Wilkins-Lee (JWL) EOS for each formulation for the best fit to the experimental data.
On the formulation of environmental fugacity models and their numerical solutions.
Bates, Michael L; Bigot, Marie; Cropp, Roger A; Engwirda, Darren; Friedman, Carey L; Hawker, Darryl W
2016-09-01
Multimedia models based on chemical fugacity, solved numerically, play an important role in investigating and quantifying the environmental fate of chemicals such as persistent organic pollutants. These models have been used extensively in studying the local and global distribution of chemicals in the environment. The present study describes potential sources of error that may arise from the formulation and numerical solution of environmental fugacity models. The authors derive a general fugacity equation for the rate of change of mass in an arbitrary volume (e.g., an environmental phase). Deriving this general equation makes clear several assumptions that are often not articulated but can be important for successfully applying multimedia fugacity models. It shows that the homogeneity of fugacity and fugacity capacity in a volume (the homogeneity assumption) is fundamental to formulating discretized fugacity models. It also shows that when using the fugacity rather than mass as the state-variable, correction terms may be necessary to accommodate environmental factors such as varying phase temperatures and volume. Neglecting these can lead to conservation errors. The authors illustrate the manifestation of these errors using heuristic multimedia fugacity models. The authors also show that there are easily avoided errors that can arise in mass state-variable models if variables are not updated appropriately in the numerical integration scheme. Environ Toxicol Chem 2016;35:2182-2191. © 2016 SETAC. PMID:26889639
Scheidegger, Stephan; Lutters, Gerd; Bodis, Stephan
2011-09-01
A kinetic bio-mathematical, linear-quadratic (LQ) based model description for clonogenic survival is presented. In contrast to widely used formulations of models, a dynamic approach based on ordinary differential equations for coupling a repair model with a tumour growth model is used to allow analysis of intercellular process dynamics and submodel interference. The purpose of the model formulation is to find a quantitative framework for investigation of tumour response to radiotherapy in vivo. It is not the intention of the proposed model formulation to give a mechanistic explanation for cellular repair processes. This article addresses bio-mathematical aspects of the simplistic kinetic approach used for description of repair. The model formulation includes processes for cellular death, repopulation and cellular repair. The explicit use of the population size in the model facilitates the coupling of the sub-models including aspects of tissue dynamics (competition, oxygenation). The cellular repair is summarized by using a kinetic model for a dose equivalent Γ describing production and elimination of sublethal lesions. This dose equivalent replaces the absorbed dose used in the common LQ- model. Therefore, this approach is called the Γ- LQ- formulation. A comparison with two kinetic radiobiological models (the LPL model of Curtis and the compartmental model of Carlone) is carried out. The resulting differential equations are solved by numerical integration using a Runge-Kutta algorithm. The comparison reveals a good agreement between the Γ- LQ- formulation and the models of Curtis and Carlone under certain, defined conditions: The proposed formulation leads to results which are identical to the model of Carlone over a wide range of investigated biological parameters and different fractionation schemes when using first order repair kinetics. The comparison with experimental data and the LPL- model of Curtis shows a good agreement of the Γ- LQ- formulation using
NASA Astrophysics Data System (ADS)
Svensson, Jenny; Johansson, Ann; Bendsoe, Niels; Gräfe, Susanna; Trebst, Tilmann; Andersson-Engels, Stefan; Svanberg, Katarina
2007-02-01
Meso-tetra(hydroxyphenyl)chlorin (mTHPC)(international generic name Temoporfin) is a potent photosensitizer used for photodynamic therapy (PDT). In this study the pharmacokinetics of a systemically administered novel lipid formulation of Temoporfin in a murine tumor model has been investigated. Fluorescence spectroscopy measurements were performed at several time intervals following drug administration, yielding information on the Temoporfin concentration within excised internal organs as a function of time after injection. Both point-monitoring and imaging setups were used. The acquired fluorescence data were correlated to the concentration of Temoporfin obtained with High Performance Liquid Chromatography (HPLC). There was a significant correlation between the fluorescence methods and HPLC for most organs investigated. The pharmacokinetics of this new liposomal formulation of Temoporfin exhibited a rather flat temporal profile in the time interval 2-8 hours in this study.
Fortuna, Lisa R.; Porche, Michelle V.; Alegría, Margarita
2010-01-01
The Cultural Formulation of Diagnosis (CFD) Model of the Diagnostic and Statistical Manual (DSM) provides a potential framework for improving the diagnostic assessment of Posttraumatic Stress Disorder (PTSD) in culturally diverse patients. We analyzed data from the Patient-Provider Encounter Study, a multisite study that examines the process of diagnosis and clinical decision-making during an initial clinical intake session, in order to examine use of CFD for PTSD diagnosis. We find that the use of the CFD in routine community settings is inconsistently or underutilized in practice, but when employed may assist the formulation and interpretation of traumatic experiences. We discuss the implications for improving the assessment of PTSD in the time-limited setting of the clinical intake encounter and across race/ethnicity. PMID:19837780
Early Formulation Model-centric Engineering on NASA's Europa Mission Concept Study
NASA Technical Reports Server (NTRS)
Bayer, Todd; Chung, Seung; Cole, Bjorn; Cooke, Brian; Dekens, Frank; Delp, Chris; Gontijo, Ivair; Lewis, Kari; Moshir, Mehrdad; Rasmussen, Robert; Wagner, David
2012-01-01
The proposed Jupiter Europa Orbiter and Jupiter Ganymede Orbiter missions were formulated using current state-of-the-art MBSE facilities: - JPL's TeamX, Rapid Mission Architecting - ESA's Concurrent Design Facility - APL's ACE Concurrent Engineering Facility. When JEO became an official "pre-project" in Sep 2010, we had already developed a strong partnership with JPL's Integrated Model Centric Engineering (IMCE) initiative; decided to apply Architecting and SysML-based MBSE from the beginning, begun laying these foundations to support work in Phase A. Release of Planetary Science Decadal Survey and FY12 President's Budget in March 2011 changed the landscape. JEO reverted to being a pre-phase A study. A conscious choice was made to continue application of MBSE on the Europa Study, refocused for early formulation. This presentation describes the approach, results, and lessons.
NASA Astrophysics Data System (ADS)
Alsaleh, Mustafa I.; Voyiadjis, George Z.; Alshibli, Khalid A.
2006-12-01
It has been known that classical continuum mechanics laws fail to describe strain localization in granular materials due to the mathematical ill-posedness and mesh dependency. Therefore, a non-local theory with internal length scales is needed to overcome such problems. The micropolar and high-order gradient theories can be considered as good examples to characterize the strain localization in granular materials. The fact that internal length scales are needed requires micromechanical models or laws; however, the classical constitutive models can be enhanced through the stress invariants to incorporate the Micropolar effects. In this paper, Lade's single hardening model is enhanced to account for the couple stress and Cosserat rotation and the internal length scales are incorporated accordingly. The enhanced Lade's model and its material properties are discussed in detail; then the finite element formulations in the Updated Lagrangian Frame (UL) are used. The finite element formulations were implemented into a user element subroutine for ABAQUS (UEL) and the solution method is discussed in the companion paper. The model was found to predict the strain localization in granular materials with low dependency on the finite element mesh size. The shear band was found to reflect on a certain angle when it hit a rigid boundary. Applications for the model on plane strain specimens tested in the laboratory are discussed in the companion paper. Copyright
Early Formulation Model-centric Engineering on Nasa's Europa Mission Concept Study
NASA Technical Reports Server (NTRS)
Bayer, Todd; Chung, Seung; Cole, Bjorn; Cooke, Brian; Dekens, Frank; Delp, Chris; Gontijo, I.; Lewis, Kari; Moshir, Mehrdad; Rasmussen, Robert; Wagner, David
2012-01-01
By leveraging the existing Model-Based Systems Engineering (MBSE) infrastructure at JPL and adding a modest investment, the Europa Mission Concept Study made striking advances in mission concept capture and analysis. This effort has reaffirmed the importance of architecting and successfully harnessed the synergistic relationship of system modeling to mission architecting. It clearly demonstrated that MBSE can provide greater agility than traditional systems engineering methods. This paper will describe the successful application of MBSE in the dynamic environment of early mission formulation, the significant results produced and lessons learned in the process.
Wall-models for large eddy simulation based on a generic additive-filter formulation
NASA Astrophysics Data System (ADS)
Sanchez Rocha, Martin
Based on the philosophy of only resolving the large scales of turbulent motion, Large Eddy Simulation (LES) has demonstrated potential to provide high-fidelity turbulence simulations at low computational cost. However, when the scales that control the turbulence in a particular flow are not large, LES has to increase significantly its computational cost to provide accurate predictions. This is the case in wall-bounded flows, where the grid resolution required by LES to resolve the near-wall structures is close to the requirements to resolve the smallest dissipative scales in turbulence. Therefore, to reduce this demanding requirement, it has been proposed to model the near-wall region with Reynolds-Averaged Navier-Stokes (RANS) models, in what is known as hybrid RANS/LES approach. In this work, the mathematical implications of merging two different turbulence modeling approaches are addressed by deriving the exact hybrid RANS/LES Navier-Stokes equations. These equations are derived by introducing an additive-filter, which linearly combines the RANS and LES operators with a blending function. The equations derived with the additive-filter predict additional hybrid terms, which represent the interactions between RANS and LES formulations. Theoretically, the prediction of the hybrid terms demonstrates that the hybridization of the two approaches cannot be accomplished only by the turbulence model equations, as it is claimed in current hybrid RANS/LES models. The importance of the exact hybrid RANS/LES equations is demonstrated by conducting numerical calculations on a turbulent flat-plate boundary layer. Results indicate that the hybrid terms help to maintain an equilibrated model transition when the hybrid formulation switches from RANS to LES. Results also indicate, that when the hybrid terms are not included, the accuracy of the calculations strongly relies on the blending function implemented in the additive-filter. On the other hand, if the exact equations are
An energetic formulation of a one-dimensional model of superelastic SMA
NASA Astrophysics Data System (ADS)
Pham, Kim
2014-03-01
This paper presents an energetic framework for the study of the macroscopic evolution of shape memory alloys (SMA) with softening behavior. It is written for a class of standard rate-independent materials with an internal variable derived from the Drucker-Ilyushin work property. This one-dimensional model is defined by three material functions of the internal variable and one material parameter. The quasi-static evolution is formulated for a one-dimensional bar under traction and is based on two physical principles: a stability criterion which consists in selecting the local minima of the total energy and an energy balance condition which requires the absolute continuity of the total energy. The stability criterion aims to overcome the non-uniqueness issue associated with the intrinsic softening character of SMA while the energy balance condition accounts for evolutions even with possible time discontinuities. While being consistent with the classical Kuhn-Tucker formulation of the phase transformations, such energetic formulation proved to be more suitable than this latter for the study of stress-softening SMA. Both homogeneous and non-homogenous solutions are investigated with respect to this variational evolution problem. Specifically, we show the instability of the homogeneous states for softening materials and construct, in this latter case, a non-homogeneous stable evolution that follows a transformation stress line which corresponds to the Maxwell line of the softening intrinsic behavior.
NASA Astrophysics Data System (ADS)
Toro, S.; Sánchez, P. J.; Podestá, J. M.; Blanco, P. J.; Huespe, A. E.; Feijóo, R. A.
2016-07-01
The paper describes the computational aspects and numerical implementation of a two-scale cohesive surface methodology developed for analyzing fracture in heterogeneous materials with complex micro-structures. This approach can be categorized as a semi-concurrent model using the representative volume element concept. A variational multi-scale formulation of the methodology has been previously presented by the authors. Subsequently, the formulation has been generalized and improved in two aspects: (i) cohesive surfaces have been introduced at both scales of analysis, they are modeled with a strong discontinuity kinematics (new equations describing the insertion of the macro-scale strains, into the micro-scale and the posterior homogenization procedure have been considered); (ii) the computational procedure and numerical implementation have been adapted for this formulation. The first point has been presented elsewhere, and it is summarized here. Instead, the main objective of this paper is to address a rather detailed presentation of the second point. Finite element techniques for modeling cohesive surfaces at both scales of analysis (FE^2 approach) are described: (i) finite elements with embedded strong discontinuities are used for the macro-scale simulation, and (ii) continuum-type finite elements with high aspect ratios, mimicking cohesive surfaces, are adopted for simulating the failure mechanisms at the micro-scale. The methodology is validated through numerical simulation of a quasi-brittle concrete fracture problem. The proposed multi-scale model is capable of unveiling the mechanisms that lead from the material degradation phenomenon at the meso-structural level to the activation and propagation of cohesive surfaces at the structural scale.
Schunk, Peter Randall; Cairncross, Richard A.; Madasu, S.
2004-03-01
This report summarizes research advances pursued with award funding issued by the DOE to Drexel University through the Presidential Early Career Award (PECASE) program. Professor Rich Cairncross was the recipient of this award in 1997. With it he pursued two related research topics under Sandia's guidance that address the outstanding issue of fluid-structural interactions of liquids with deformable solid materials, focusing mainly on the ubiquitous dynamic wetting problem. The project focus in the first four years was aimed at deriving a predictive numerical modeling approach for the motion of the dynamic contact line on a deformable substrate. A formulation of physical model equations was derived in the context of the Galerkin finite element method in an arbitrary Lagrangian/Eulerian (ALE) frame of reference. The formulation was successfully integrated in Sandia's Goma finite element code and tested on several technologically important thin-film coating problems. The model equations, the finite-element implementation, and results from several applications are given in this report. In the last year of the five-year project the same physical concepts were extended towards the problem of capillary imbibition in deformable porous media. A synopsis of this preliminary modeling and experimental effort is also discussed.
A density-scaled continuum surface force model within a balanced force formulation
NASA Astrophysics Data System (ADS)
Yokoi, Kensuke
2014-12-01
We propose a numerical framework which can simulate free surface flows with complex moving interfaces like droplet splashing as minimizing spurious currents. The numerical framework is based on the CLSVOF (coupled level set and volume-of-fluid) method, the THINC/WLIC (tangent of hyperbola for interface capturing/weighted line interface calculation) scheme, multi-moment methods (CIP-CSL and VSIAM3) and density-scaled CSF (continuum surface force) model within a balanced force formulation. In this paper, we propose a level set based algorithm of the density-scaled balanced CSF model and show that the density-scaled balanced CSF model can reduce spurious currents more than the standard balanced CSF model without using the density-scaling when the exact curvature is not given. We also show that the numerical framework can well capture the physics of droplet splashing.
Sondak, David; Oberai, Assad A.
2012-10-15
Novel large eddy simulation (LES) models are developed for incompressible magnetohydrodynamics (MHD). These models include the application of the variational multiscale formulation of LES to the equations of incompressible MHD. Additionally, a new residual-based eddy viscosity model is introduced for MHD. A mixed LES model that combines the strengths of both of these models is also derived. The new models result in a consistent numerical method that is relatively simple to implement. The need for a dynamic procedure in determining model coefficients is no longer required. The new LES models are tested on a decaying Taylor-Green vortex generalized to MHD and benchmarked against classical LES turbulence models. The LES simulations are run in a periodic box of size [-{pi}, {pi}]{sup 3} with 32 modes in each direction and are compared to a direct numerical simulation (DNS) with 512 modes in each direction. The new models are able to account for the essential MHD physics which is demonstrated via comparisons of energy spectra. We also compare the performance of our models to a DNS simulation by Pouquet et al.['The dynamics of unforced turbulence at high Reynolds number for Taylor-Green vortices generalized to MHD,' Geophys. Astrophys. Fluid Dyn. 104, 115-134 (2010)], for which the ratio of DNS modes to LES modes is 262:144.
Maness, Michael; Cirillo, Cinzia
2016-11-01
The current state-of-the-art in social influence models of travel behavior is conformity models with direct benefit social influence effects. Indirect effects have seen limited development, but this paper presents a latent class discrete choice model of an indirect informational conformity hypothesis. Moreover, class membership depends on the proportion of group members who adopt a behavior. Membership into the more informed class causes changes in the preferences of those individuals thus making adoption more attractive. Equilibrium properties are derived for this model showing the possibility of multiple equilibria but under different conditions than the direct-benefit formulations. Social influence elasticity is derivedmore » for both models types. The informational conformity model can represent non-linear elasticity behavior unlike the direct-benefit formulation. Additionally, a two-stage control function is developed to obtain consistent parameter estimates in the presence of an endogenous class membership model covariate that is correlated with choice model unobservables. A case study to study social influence in bicycle ownership in the United States is presented. Our results showed that more informed households had a greater chance of owning a bike due to preference changes with less sensitivity to smaller home footprints and limited incomes. The behavioral hypothesis of positive preference change due to information transfer was confirmed. Observed ownership share closely matched predicted local-level equilibrium in some metropolitan areas but was unable to achieve expected prediction rate within confidence intervals. Finally, the elasticity of social influence was found to range locally from about 0.5% to 1.0%.« less
NASA Astrophysics Data System (ADS)
Golmohammadi, Azarang; Jafarpour, Behnam
2016-06-01
Adopting representative geologic connectivity scenarios is critical for reliable modeling and prediction of flow and transport processes in subsurface environments. Geologic scenarios are often developed by integrating several sources of information, including knowledge of the depositional environment, qualitative and quantitative data such as outcrop and well logs, and process-based geologic modeling. In general, flow and transport response data are usually not included in constructing geologic scenarios for a basin. Instead, these data are typically matched using a given prior geologic scenario as constraint. Since data limitations, modeling assumptions and subjective interpretations can lead to significant uncertainty in the adopted geologic scenarios, flow and transport data may also be useful for constraining the uncertainty in proposed geologic scenarios. Constraining geologic scenarios with flow-related data opens an interesting and challenging research area, which goes beyond the traditional model calibration formulations where the geologic scenario is assumed given. In this paper, a novel concept, known as group-sparsity regularization, is proposed as an effective formulation to constrain the uncertainty in the prior geologic scenario during subsurface flow model calibration. Given a collection of model realizations from several plausible geologic scenarios, the proposed method first applies the truncated singular value decomposition (TSVD) to compactly represent the models from each geologic scenario. The TSVD basis for representing each scenario forms a distinct group. The proposed approach searches over these groups (i.e., geologic scenarios) to eliminate inconsistent groups that are not supported by the observed flow/pressure data. The group-sparsity regularization minimizes a l1/l2mixed norm, where the l2-norm quantifies the contribution of each group and operates on the coefficients within the groups while the l1-norm, having a selection property, is
NASA Technical Reports Server (NTRS)
Biess, J. J.; Yu, Y.; Middlebrook, R. D.; Schoenfeld, A. D.
1974-01-01
A review is given of future power processing systems planned for the next 20 years, and the state-of-the-art of power processing design modeling and analysis techniques used to optimize power processing systems. A methodology of modeling and analysis of power processing equipment and systems has been formulated to fulfill future tradeoff studies and optimization requirements. Computer techniques were applied to simulate power processor performance and to optimize the design of power processing equipment. A program plan to systematically develop and apply the tools for power processing systems modeling and analysis is presented so that meaningful results can be obtained each year to aid the power processing system engineer and power processing equipment circuit designers in their conceptual and detail design and analysis tasks.
Functional testing of topical skin formulations using an optimised ex vivo skin organ culture model.
Sidgwick, G P; McGeorge, D; Bayat, A
2016-07-01
A number of equivalent-skin models are available for investigation of the ex vivo effect of topical application of drugs and cosmaceuticals onto skin, however many have their drawbacks. With the March 2013 ban on animal models for cosmetic testing of products or ingredients for sale in the EU, their utility for testing toxicity and effect on skin becomes more relevant. The aim of this study was to demonstrate proof of principle that altered expression of key gene and protein markers could be quantified in an optimised whole tissue biopsy culture model. Topical formulations containing green tea catechins (GTC) were investigated in a skin biopsy culture model (n = 11). Punch biopsies were harvested at 3, 7 and 10 days, and analysed using qRT-PCR, histology and HPLC to determine gene and protein expression, and transdermal delivery of compounds of interest. Reduced gene expression of α-SMA, fibronectin, mast cell tryptase, mast cell chymase, TGF-β1, CTGF and PAI-1 was observed after 7 and 10 days compared with treated controls (p < 0.05). Histological analysis indicated a reduction in mast cell tryptase and chymase positive cell numbers in treated biopsies compared with untreated controls at day 7 and day 10 (p < 0.05). Determination of transdermal uptake indicated that GTCs were detected in the biopsies. This model could be adapted to study a range of different topical formulations in both normal and diseased skin, negating the requirement for animal models in this context, prior to study in a clinical trial environment. PMID:27086034
Demenais, F M; Laing, A E; Bonney, G E
1992-01-01
Segregation analysis of discrete traits can be conducted by the classical mixed model and the recently introduced regressive models. The mixed model assumes an underlying liability to the disease, to which a major gene, a multifactorial component, and random environment contribute independently. Affected persons have a liability exceeding a threshold. The regressive logistic models assume that the logarithm of the odds of being affected is a linear function of major genotype effects, the phenotypes of older relatives, and other covariates. A formulation of the regressive models, based on an underlying liability model, has been recently proposed. The regression coefficients on antecedents are expressed in terms of the relevant familial correlations and a one-to-one correspondence with the parameters of the mixed model can thus be established. Computer simulations are conducted to evaluate the fit of the two formulations of the regressive models to the mixed model on nuclear families. The two forms of the class D regressive model provide a good fit to a generated mixed model, in terms of both hypothesis testing and parameter estimation. The simpler class A regressive model, which assumes that the outcomes of children depend solely on the outcomes of parents, is not robust against a sib-sib correlation exceeding that specified by the model, emphasizing testing class A against class D. The studies reported here show that if the true state of nature is that described by the mixed model, then a regressive model will do just as well. Moreover, the regressive models, allowing for more patterns of family dependence, provide a flexible framework to understand gene-environment interactions in complex diseases. PMID:1487139
NASA Technical Reports Server (NTRS)
Winckelmans, G. S.; Lund, T. S.; Carati, D.; Wray, A. A.
1996-01-01
Subgrid-scale models for Large Eddy Simulation (LES) in both the velocity-pressure and the vorticity-velocity formulations were evaluated and compared in a priori tests using spectral Direct Numerical Simulation (DNS) databases of isotropic turbulence: 128(exp 3) DNS of forced turbulence (Re(sub(lambda))=95.8) filtered, using the sharp cutoff filter, to both 32(exp 3) and 16(exp 3) synthetic LES fields; 512(exp 3) DNS of decaying turbulence (Re(sub(Lambda))=63.5) filtered to both 64(exp 3) and 32(exp 3) LES fields. Gaussian and top-hat filters were also used with the 128(exp 3) database. Different LES models were evaluated for each formulation: eddy-viscosity models, hyper eddy-viscosity models, mixed models, and scale-similarity models. Correlations between exact versus modeled subgrid-scale quantities were measured at three levels: tensor (traceless), vector (solenoidal 'force'), and scalar (dissipation) levels, and for both cases of uniform and variable coefficient(s). Different choices for the 1/T scaling appearing in the eddy-viscosity were also evaluated. It was found that the models for the vorticity-velocity formulation produce higher correlations with the filtered DNS data than their counterpart in the velocity-pressure formulation. It was also found that the hyper eddy-viscosity model performs better than the eddy viscosity model, in both formulations.
Nandola, Naresh N; Rivera, Daniel E
2013-01-01
We consider an improved model predictive control (MPC) formulation for linear hybrid systems described by mixed logical dynamical (MLD) models. The algorithm relies on a multiple-degree-of-freedom parametrization that enables the user to adjust the speed of setpoint tracking, measured disturbance rejection and unmeasured disturbance rejection independently in the closed-loop system. Consequently, controller tuning is more flexible and intuitive than relying on objective function weights (such as move suppression) traditionally used in MPC schemes. The controller formulation is motivated by the needs of non-traditional control applications that are suitably described by hybrid production-inventory systems. Two applications are considered in this paper: adaptive, time-varying interventions in behavioral health, and inventory management in supply chains under conditions of limited capacity. In the adaptive intervention application, a hypothetical intervention inspired by the Fast Track program, a real-life preventive intervention for reducing conduct disorder in at-risk children, is examined. In the inventory management application, the ability of the algorithm to judiciously alter production capacity under conditions of varying demand is presented. These case studies demonstrate that MPC for hybrid systems can be tuned for desired performance under demanding conditions involving noise and uncertainty. PMID:24348004
NASA Astrophysics Data System (ADS)
Alimonti, L.; Atalla, N.
2016-04-01
This paper is concerned with the development of a simplified model for noise control treatments to speed up finite element analysis in vibroacoustic applications. The methodology relies on the assumption that the acoustic treatment is flat and homogeneous. Moreover, its finite lateral extent is neglected. This hypothesis is justified by short wavelength and large dissipation, which suggest that the reflected field emanating from the acoustic treatment lateral boundaries does not substantially affect its dynamic response. Under these circumstances, the response of the noise control treatment can be formally obtained by means of convolution integrals involving simple analytical kernels (i.e. Green functions). Such fundamental solutions can be computed efficiently by the transfer matrix method. However, some arbitrariness arises in the formulation of the mathematical model, resulting in different baffling conditions at the two ends of the treatment to be considered. Thus, the paper investigates the possibility of different formulations (i.e. baffling conditions) within the same hybrid finite element-transfer matrix framework, seeking for the best strategy in terms of tradeoff between efficiency and accuracy. Numerical examples are provided to show strengths and limitations of the proposed methodology.
Kim, Dong-Sang
2015-03-02
The legacy nuclear wastes stored in underground tanks at the US Department of Energy’s Hanford site is planned to be separated into high-level waste and low-activity waste fractions and vitrified separately. Formulating optimized glass compositions that maximize the waste loading in glass is critical for successful and economical treatment and immobilization of nuclear wastes. Glass property-composition models have been developed and applied to formulate glass compositions for various objectives for the past several decades. The property models with associated uncertainties and combined with composition and property constraints have been used to develop preliminary glass formulation algorithms designed for vitrification process control and waste form qualification at the planned waste vitrification plant. This paper provides an overview of current status of glass property-composition models, constraints applicable to Hanford waste vitrification, and glass formulation approaches that have been developed for vitrification of hazardous and highly radioactive wastes stored at the Hanford site.
Rivulgo, Virginia; Sparo, Mónica; Ceci, Mónica; Fumuso, Elida; Confalonieri, Alejandra; Sánchez Bruni, Sergio F.
2013-01-01
Azithromycin (AZM) therapeutic failure and relapses of patients treated with generic formulations have been observed in clinical practice. The main goal of this research was to compare in a preclinical study the serum exposure and lung tissue concentration of two commercial formulations AZM-based in murine model. The current study involved 264 healthy Balb-C. Mice were divided into two groups (n = 44): animals of Group A (reference formulation -R-) were orally treated with AZM suspension at 10 mg/kg of b.w. Experimental animals of Group B (generic formulation -G-) received identical treatment than Group A with a generic formulation AZM-based. The study was repeated twice as Phase II and III. Serum and lung tissue samples were taken 24 h post treatment. Validated microbiological assay was used to determine the serum pharmacokinetic and lung distribution of AZM. After the pharmacokinetic analysis was observed, a similar serum exposure for both formulations of AZM assayed. In contrast, statistical differences (P < 0.001) were obtained after comparing the concentrations of both formulations in lung tissue, being the values obtained for AUC and Cmax (AZM-R-) +1586 and 122%, respectively, than those obtained for AZM-G- in lung. These differences may indicate large differences on the distribution process of both formulations, which may explain the lack of efficacy/therapeutic failure observed on clinical practice. PMID:24073402
Kesisoglou, Filippos; Chung, John; van Asperen, Judith; Heimbach, Tycho
2016-09-01
In recent years, there has been a significant increase in use of physiologically based pharmacokinetic models in drug development and regulatory applications. Although most of the published examples have focused on aspects such as first-in-human (FIH) dose predictions or drug-drug interactions, several publications have highlighted the application of these models in the biopharmaceutics field and their use to inform formulation development. In this report, we present 5 case studies of use of such models in this biopharmaceutics/formulation space across different pharmaceutical companies. The case studies cover different aspects of biopharmaceutics or formulation questions including (1) prediction of absorption prior to FIH studies; (2) optimization of formulation and dissolution method post-FIH data; (3) early exploration of a modified-release formulation; (4) addressing bridging questions for late-stage formulation changes; and (5) prediction of pharmacokinetics in the fed state for a Biopharmaceutics Classification System class I drug with fasted state data. The discussion of the case studies focuses on how such models can facilitate decisions and biopharmaceutic understanding of drug candidates and the opportunities for increased use and acceptance of such models in drug development and regulatory interactions. PMID:26886317
Reversible Discrete Event Formulation and Optimistic Parallel Execution of Vehicular Traffic Models
Yoginath, Srikanth B; Perumalla, Kalyan S
2009-01-01
Vehicular traffic simulations are useful in applications such as emergency planning and traffic management. High speed of traffic simulations translates to speed of response and level of resilience in those applications. Discrete event formulation of traffic flow at the level of individual vehicles affords both the flexibility of simulating complex scenarios of vehicular flow behavior as well as rapid simulation time advances. However, efficient parallel/distributed execution of the models becomes challenging due to synchronization overheads. Here, a parallel traffic simulation approach is presented that is aimed at reducing the time for simulating emergency vehicular traffic scenarios. Our approach resolves the challenges that arise in parallel execution of microscopic, vehicular-level models of traffic. We apply a reverse computation-based optimistic execution approach to address the parallel synchronization problem. This is achieved by formulating a reversible version of a discrete event model of vehicular traffic, and by utilizing this reversible model in an optimistic execution setting. Three unique aspects of this effort are: (1) exploration of optimistic simulation applied to vehicular traffic simulation (2) addressing reverse computation challenges specific to optimistic vehicular traffic simulation (3) achieving absolute (as opposed to self-relative) speedup with a sequential speed close to that of a fast, de facto standard sequential simulator for emergency traffic. The design and development of the parallel simulation system is presented, along with a performance study that demonstrates excellent sequential performance as well as parallel performance. The benefits of optimistic execution are demonstrated, including a speed up of nearly 20 on 32 processors observed on a vehicular network of over 65,000 intersections and over 13 million vehicles.
NASA Technical Reports Server (NTRS)
Makel, Darby B.; Rosenberg, Sanders D.
1990-01-01
The formation and deposition of carbon (soot) was studied in the Carbon Deposition Model for Oxygen-Hydrocarbon Combustion Program. An empirical, 1-D model for predicting soot formation and deposition in LO2/hydrocarbon gas generators/preburners was derived. The experimental data required to anchor the model were identified and a test program to obtain the data was defined. In support of the model development, cold flow mixing experiments using a high injection density injector were performed. The purpose of this investigation was to advance the state-of-the-art in LO2/hydrocarbon gas generator design by developing a reliable engineering model of gas generator operation. The model was formulated to account for the influences of fluid dynamics, chemical kinetics, and gas generator hardware design on soot formation and deposition.
Active behavior of abdominal wall muscles: Experimental results and numerical model formulation.
Grasa, J; Sierra, M; Lauzeral, N; Muñoz, M J; Miana-Mena, F J; Calvo, B
2016-08-01
In the present study a computational finite element technique is proposed to simulate the mechanical response of muscles in the abdominal wall. This technique considers the active behavior of the tissue taking into account both collagen and muscle fiber directions. In an attempt to obtain the computational response as close as possible to real muscles, the parameters needed to adjust the mathematical formulation were determined from in vitro experimental tests. Experiments were conducted on male New Zealand White rabbits (2047±34g) and the active properties of three different muscles: Rectus Abdominis, External Oblique and multi-layered samples formed by three muscles (External Oblique, Internal Oblique, and Transversus Abdominis) were characterized. The parameters obtained for each muscle were incorporated into a finite strain formulation to simulate active behavior of muscles incorporating the anisotropy of the tissue. The results show the potential of the model to predict the anisotropic behavior of the tissue associated to fibers and how this influences on the strain, stress and generated force during an isometric contraction. PMID:27111629
Binyamin, Orli; Larush, Liraz; Frid, Kati; Keller, Guy; Friedman-Levi, Yael; Ovadia, Haim; Abramsky, Oded; Magdassi, Shlomo; Gabizon, Ruth
2015-01-01
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system and is associated with demyelination, neurodegeneration, and sensitivity to oxidative stress. In this work, we administered a nanodroplet formulation of pomegranate seed oil (PSO), denominated Nano-PSO, to mice induced for experimental autoimmune encephalomyelitis (EAE), an established model of MS. PSO comprises high levels of punicic acid, a unique polyunsaturated fatty acid considered as one of the strongest natural antioxidants. We show here that while EAE-induced mice treated with natural PSO presented some reduction in disease burden, this beneficial effect increased significantly when EAE mice were treated with Nano-PSO of specific size nanodroplets at much lower concentrations of the oil. Pathological examinations revealed that Nano-PSO administration dramatically reduced demyelination and oxidation of lipids in the brains of the affected animals, which are hallmarks of this severe neurological disease. We propose that novel formulations of natural antioxidants such as Nano-PSO may be considered for the treatment of patients suffering from demyelinating diseases. On the mechanistic side, our results demonstrate that lipid oxidation may be a seminal feature in both demyelination and neurodegeneration. PMID:26648720
Silverman, Morton M
2014-09-01
Suicide and other suicidal behaviors are often associated with psychiatric disorders and dysfunctions. Therefore, psychiatrists have significant opportunities to identify at-risk individuals and offer treatment to reduce that risk. Although a suicide risk assessment is a core competency requirement, many clinical psychiatrists lack the requisite training and skills to appropriately assess for suicide risk. Moreover, the standard of care requires psychiatrists to foresee the possibility that a patient might engage in suicidal behavior, hence to conduct a suicide risk formulation sufficient to guide triage and treatment planning. Based on data collected via a suicide risk assessment, a suicide risk formulation is a process whereby the psychiatrist forms a judgment about a patient's foreseeable risk of suicidal behavior in order to inform triage decisions, safety and treatment planning, and interventions to reduce risk. This paper addresses the components of this process in the context of the model for therapeutic risk management of the suicidal patient developed at the Veterans Integrated Service Network (VISN) 19 Mental Illness Research, Education and Clinical Center by Wortzel et al. PMID:25226200
Corcelli, S.A.; Kress, J.D.; Pratt, L.R.
1995-08-07
This paper develops and characterizes mixed direct-iterative methods for boundary integral formulations of continuum dielectric solvation models. We give an example, the Ca{sup ++}{hor_ellipsis}Cl{sup {minus}} pair potential of mean force in aqueous solution, for which a direct solution at thermal accuracy is difficult and, thus for which mixed direct-iterative methods seem necessary to obtain the required high resolution. For the simplest such formulations, Gauss-Seidel iteration diverges in rare cases. This difficulty is analyzed by obtaining the eigenvalues and the spectral radius of the non-symmetric iteration matrix. This establishes that those divergences are due to inaccuracies of the asymptotic approximations used in evaluation of the matrix elements corresponding to accidental close encounters of boundary elements on different atomic spheres. The spectral radii are then greater than one for those diverging cases. This problem is cured by checking for boundary element pairs closer than the typical spatial extent of the boundary elements and for those cases performing an ``in-line`` Monte Carlo integration to evaluate the required matrix elements. These difficulties are not expected and have not been observed for the thoroughly coarsened equations obtained when only a direct solution is sought. Finally, we give an example application of hybrid quantum-classical methods to deprotonation of orthosilicic acid in water.
A multibody motorcycle model with rigid-ring tyres: formulation and validation
NASA Astrophysics Data System (ADS)
Leonelli, Luca; Mancinelli, Nicolò
2015-06-01
The aim of this paper is the development and validation of a three-dimensional multibody motorcycle model including a rigid-ring tyre model, taking into account both the slopes and elevation of the road surface. In order to achieve accurate assessment of ride and handling performances of a road racing motorcycle, a tyre model capable of reproducing the dynamic response to actual road excitation is required. While a number of vehicle models with such feature are available for car application, the extension to the motorcycle modelling has not been addressed yet. To do so, a novel parametrisation for the general motorcycle kinematics is proposed, using a mixed reference point and relative coordinates approach. The resulting description, developed in terms of dependent coordinates, makes it possible to include the rigid-ring kinematics as well as road elevation and slopes, without affecting computational efficiency. The equations of motion for the whole multibody system are derived symbolically and the constraint equations arising from the dependent coordinate formulation are handled using the position and velocity vector projection technique. The resulting system of equations is integrated in time domain using a standard ordinary differential equation (ODE) algorithm. Finally, the model is validated with respect to experimentally measured data in both time and frequency domains.
Plan, formulate, and discuss a NASTRAN finite element model of the UH-60A helicopter airframe
NASA Technical Reports Server (NTRS)
Dinyovszky, P.; Twomey, W. J.
1990-01-01
Under a rotorcraft structural dynamics program sponsored by the NASA Langley Research Center, Sikorsky Aircraft, together with the other major helicopter airframe manufacturers, is engaged in a study to improve the use of finite element analysis to predict the dynamic behavior of helicopter airframes. This program, which was designated DAMVIBS (Design Analysis Methods for VIBrationS), includes activities in the areas of: planning, creating, and documenting finite element models of helicopter airframes; the performance of ground vibration tests; and the correlation of test and analysis. The work performed at Sikorsky Aircraft for planning, creating, and documenting a finite element model of the UH-60A BLACK HAWK helicopter airframe is summarized. A complete description of the components of the helicopter which are to be represented in the model is presented and includes: the structural arrangement, the identification of primary and secondary structure, the components of the drive and power trains, and the attachment of large weight items to the structure. Also presented are the techniques which were used to formulate the structural finite element model for static analysis, for forming the mass and vibration models for dynamic analysis, and the procedures which were used to check out and verify the integrity of the model. Initial predictions for the vibration modes for the helicopter are included.
Wang, Tao; He, Peng; Ahn, Kwang Woo; Wang, Xujing; Ghosh, Soumitra; Laud, Purushottam
2015-01-01
The generalized linear mixed model (GLMM) is a useful tool for modeling genetic correlation among family data in genetic association studies. However, when dealing with families of varied sizes and diverse genetic relatedness, the GLMM has a special correlation structure which often makes it difficult to be specified using standard statistical software. In this study, we propose a Cholesky decomposition based re-formulation of the GLMM so that the re-formulated GLMM can be specified conveniently via “proc nlmixed” and “proc glimmix” in SAS, or OpenBUGS via R package BRugs. Performances of these procedures in fitting the re-formulated GLMM are examined through simulation studies. We also apply this re-formulated GLMM to analyze a real data set from Type 1 Diabetes Genetics Consortium (T1DGC). PMID:25873936
Overton, J.H. Jr.
1984-01-01
The major physical and chemical processes involved in the transport and absorption of O/sub 3/ or NO/sub 2/ in the lower respiratory tract are discussed. This included the development of respiratory tract models, flow patterns, and transport in tube networks, the mucous, surfactant, and tissue layers, and chemical reactions and transport of O/sub 3/ or NO/sub 2/ within these layers. Descriptions of the individual processes are simplified and integrated to illustrate the formulation of dosimetry models. Data from a dosimetry model, formulated from the concepts discussed, are used to illustrate the types of information obtained by modeling. 31 references.
Täuber, Anja; Müller-Goymann, Christel C
2016-05-30
The in vitro efficacy of poloxamer 407-based formulations with antifungal ciclopirox olamine has been analysed in an infected nail plate model. As artificial nail plates, keratin films made of human hair keratin and slices from bovine hooves have been utilised. Several poloxamer 407-based formulations with 1 % active ingredient indicated complete growth inhibition of the dermatophyte fungus Trichophyton rubrum after 6days of incubation. PMID:26992819
Azeemuddin, Mohammed; Viswanatha, Gollapalle Lakshminarayanashastry; Thippeswamy, Agadi HireMath; Baig, Mirza Rizwan; Kavya, Kethaganahalli Jayaramaiah; Patki, Pralhad Sadashiv; Shyam, Ramakrishnan
2014-01-01
Objective. To improve the existing experimental model of croton oil-induced hemorrhoids in rats by using Evans Blue (EB) dye extravasation technique. Further, an herbal formulation (Pilex) was evaluated for its antihemorrhoidal activity in this model. Methods. Two sets of experiments were carried out: first to improve the experimental model and to validate the same using Pilex and second to evaluate the effect of Pilex on cytoarchitecture of rectoanal tissue in croton oil-induced hemorrhoids. In both sets, hemorrhoids were induced to all the animals, except normal controls, by applying croton oil via rectoanal region and the effect of Pilex ointment (PO), Pilex granules (PG), and combination of PG and PO was evaluated. In the first set, extravasation of EB dye, TNF-α, IL-6, and rectoanal coefficient (RAC) was determined. In the second set, severity of score, RAC, and histopathology were evaluated. Results. The elevated levels of TNF-α, IL-6, and extravasations of EB dye were decreased with the Pilex treatment. The cytoarchitecture of rectoanal portion of the animals treated with Pilex was near to normal. Conclusion. The improved experimental model of hemorrhoid is useful in quantifying the inflammatory exudates and extent of inflammation. In this improved experimental model Pilex showed antihemorrhoidal activity, which further validates its clinical usage. PMID:25006493
Chen, Z.; Schreyer, H.L.
1995-09-01
The response of underground structures and transportation facilities under various external loadings and environments is critical for human safety as well as environmental protection. Since quasi-brittle materials such as concrete and rock are commonly used for underground construction, the constitutive modeling of these engineering materials, including post-limit behaviors, is one of the most important aspects in safety assessment. From experimental, theoretical, and computational points of view, this report considers the constitutive modeling of quasi-brittle materials in general and concentrates on concrete in particular. Based on the internal variable theory of thermodynamics, the general formulations of plasticity and damage models are given to simulate two distinct modes of microstructural changes, inelastic flow and degradation of material strength and stiffness, that identify the phenomenological nonlinear behaviors of quasi-brittle materials. The computational aspects of plasticity and damage models are explored with respect to their effects on structural analyses. Specific constitutive models are then developed in a systematic manner according to the degree of completeness. A comprehensive literature survey is made to provide the up-to-date information on prediction of structural failures, which can serve as a reference for future research.
Integral formulation of shallow-water equations with anisotropic porosity for urban flood modeling
NASA Astrophysics Data System (ADS)
Sanders, Brett F.; Schubert, Jochen E.; Gallegos, Humberto A.
2008-11-01
SummaryAn integral form of the shallow-water equations suitable for urban flood modeling is derived by applying Reynolds transport theorem to a finite control volume encompassing buildings on a flood plain. The effect of buildings on storage and conveyance is modeled with a binary density function i(x,y) that equals unity when (x,y) corresponds to a void, and nil otherwise, and can be measured using remote sensing data such as classified aerial imagery; the effect of buildings on flow resistance is modeled with a drag formulation. Discrete equations are obtained by applying the integral equations to a computational cell and adopting a Godunov-type, piecewise linear distribution of flow variables. The discrete equations include a volumetric porosity ϕ that represents the integral of i over the cell, normalized by the cell area, and an areal porosity ψ that represents the integral of i over an edge of the mesh, normalized by the edge length. The latter is directionally dependent which introduces anisotropy to the shallow-water equations and captures sub-grid preferential flow directions which occur in urban settings due to asymmetric building shapes and spacings and the alignment of buildings along streets. A important implication is that model predictions are necessarily grid dependent; therefore, a mesh design strategy is proposed. First- and second-order accurate numerical methods are presented to solve the discrete equations, and applications are shown for verification and validation purposes including the ability of the model to resolve preferential flow directions.
Mitsos, Alexander; Melas, Ioannis N; Morris, Melody K; Saez-Rodriguez, Julio; Lauffenburger, Douglas A; Alexopoulos, Leonidas G
2012-01-01
Modeling of signal transduction pathways plays a major role in understanding cells' function and predicting cellular response. Mathematical formalisms based on a logic formalism are relatively simple but can describe how signals propagate from one protein to the next and have led to the construction of models that simulate the cells response to environmental or other perturbations. Constrained fuzzy logic was recently introduced to train models to cell specific data to result in quantitative pathway models of the specific cellular behavior. There are two major issues in this pathway optimization: i) excessive CPU time requirements and ii) loosely constrained optimization problem due to lack of data with respect to large signaling pathways. Herein, we address both issues: the former by reformulating the pathway optimization as a regular nonlinear optimization problem; and the latter by enhanced algorithms to pre/post-process the signaling network to remove parts that cannot be identified given the experimental conditions. As a case study, we tackle the construction of cell type specific pathways in normal and transformed hepatocytes using medium and large-scale functional phosphoproteomic datasets. The proposed Non Linear Programming (NLP) formulation allows for fast optimization of signaling topologies by combining the versatile nature of logic modeling with state of the art optimization algorithms. PMID:23226239
Empirical modeling of the fine particle fraction for carrier-based pulmonary delivery formulations
Pacławski, Adam; Szlęk, Jakub; Lau, Raymond; Jachowicz, Renata; Mendyk, Aleksander
2015-01-01
In vitro study of the deposition of drug particles is commonly used during development of formulations for pulmonary delivery. The assay is demanding, complex, and depends on: properties of the drug and carrier particles, including size, surface characteristics, and shape; interactions between the drug and carrier particles and assay conditions, including flow rate, type of inhaler, and impactor. The aerodynamic properties of an aerosol are measured in vitro using impactors and in most cases are presented as the fine particle fraction, which is a mass percentage of drug particles with an aerodynamic diameter below 5 μm. In the present study, a model in the form of a mathematical equation was developed for prediction of the fine particle fraction. The feature selection was performed using the R-environment package “fscaret”. The input vector was reduced from a total of 135 independent variables to 28. During the modeling stage, techniques like artificial neural networks, genetic programming, rule-based systems, and fuzzy logic systems were used. The 10-fold cross-validation technique was used to assess the generalization ability of the models created. The model obtained had good predictive ability, which was confirmed by a root-mean-square error and normalized root-mean-square error of 4.9 and 11%, respectively. Moreover, validation of the model using external experimental data was performed, and resulted in a root-mean-square error and normalized root-mean-square error of 3.8 and 8.6%, respectively. PMID:25653522
Chen, W; Desai, D; Good, D; Crison, J; Timmins, P; Paruchuri, S; Wang, J; Ha, K
2016-08-01
A computational fluid dynamic (CFD) model was developed to predict metformin release from a hydroxypropylmethylcellulose (HPMC) matrix-based extended-release formulation that took into consideration the physical and chemical properties of the drug substance, composition, as well as size and shape of the tablet. New high dose strength (1000 mg) tablet geometry was selected based on the surface area/volume (SA/V) approach advocated by Lapidus/Lordi/Reynold to obtain the desired equivalent metformin release kinetics. Maintaining a similar SA/V ratio across all extended-release metformin hydrochloride (Met XR) tablet strengths that had different geometries provided similar simulations of dissolution behavior. Experimental dissolution profiles of three lots of high-strength tablets agreed with the simulated release kinetics. Additionally, a pharmacokinetic absorption model was developed using GastroPlus™ software and known physicochemical, pharmacokinetic, and in vitro dissolution properties of metformin to predict the clinical exposure of the new high strength (1000 mg) tablet prior to conducting a human clinical bioequivalence study. In vitro metformin release kinetics were utilized in the absorption model to predict exposures in humans for new 1000-mg Met XR tablets, and the absorption model correctly projected equivalent in vivo exposure across all dose strengths. A clinical bioequivalence study was pursued based on the combined modeling results and demonstrated equivalent exposure as predicted by the simulations. PMID:26729531
A novel formulation for scratch-based wear modelling in total hip arthroplasty.
Kruger, Karen M; Tikekar, Nishant M; Heiner, Anneliese D; Baer, Thomas E; Lannutti, John J; Callaghan, John J; Brown, Thomas D
2014-01-01
Damage to the femoral head in total hip arthroplasty often takes the form of discrete scratches, which can lead to dramatic wear acceleration of the polyethylene (PE) liner. Here, a novel formulation is reported for finite element (FE) analysis of wear acceleration due to scratch damage. A diffused-light photography technique was used to globally locate areas of damage, providing guidance for usage of high-magnification optical profilometry to determine individual scratch morphology. This multiscale image combination allowed comprehensive input of scratch-based damage patterns to an FE Archard wear model, to determine the wear acceleration associated with specific retrieval femoral heads. The wear algorithm imposed correspondingly elevated wear factors on areas of PE incrementally overpassed by individual scratches. Physical validation was provided by agreement with experimental data for custom-ruled scratch patterns. Illustrative wear acceleration results are presented for four retrieval femoral heads. PMID:23305334
A Novel Formulation for Scratch-Based Wear Modeling in Total Hip Arthroplasty
Kruger, Karen M.; Tikekar, Nishant M.; Heiner, Anneliese D.; Baer, Thomas E.; Lannutti, John J.; Callaghan, John J.; Brown, Thomas D.
2013-01-01
Damage to the femoral head in total hip arthroplasty often takes the form of discrete scratches, which can lead to dramatic wear acceleration of the polyethylene (PE) liner. Here, a novel formulation is reported for finite element analysis of wear acceleration due to scratch damage. A diffused-light photography technique was used to globally locate areas of damage, providing guidance for usage of high-magnification optical profilometry to determine individual scratch morphology. This multiscale image combination allowed comprehensive input of scratch-based damage patterns to a finite element (FE) Archard wear model, to determine the wear acceleration associated with specific retrieval femoral heads. The wear algorithm imposed correspondingly elevated wear factors on areas of PE incrementally overpassed by individual scratches. Physical validation was provided by agreement with experimental data for custom-ruled scratch patterns. Illustrative wear acceleration results are presented for four retrieval femoral heads. PMID:23305334
Costabile, Adele; Walton, Gemma E.; Tzortzis, George; Vulevic, Jelena; Charalampopoulos, Dimitris; Gibson, Glenn R.
2015-01-01
A three-stage continuous fermentative colonic model system was used to monitor in vitro the effect of different orange juice formulations on prebiotic activity. Three different juices with and without Bimuno, a GOS mixture containing galactooligosaccharides (B-GOS) were assessed in terms of their ability to induce a bifidogenic microbiota. The recipe development was based on incorporating 2.75g B-GOS into a 250 ml serving of juice (65°Brix of concentrate juice). Alongside the production of B-GOS juice, a control juice – orange juice without any additional Bimuno and a positive control juice, containing all the components of Bimuno (glucose, galactose and lactose) in the same relative proportions with the exception of B-GOS were developed. Ion Exchange Chromotography analysis was used to test the maintenance of bimuno components after the production process. Data showed that sterilisation had no significant effect on concentration of B-GOS and simple sugars. The three juice formulations were digested under conditions resembling the gastric and small intestinal environments. Main bacterial groups of the faecal microbiota were evaluated throughout the colonic model study using 16S rRNA-based fluorescence in situ hybridization (FISH). Potential effects of supplementation of the juices on microbial metabolism were studied measuring short chain fatty acids (SCFAs) using gas chromatography. Furthermore, B-GOS juices showed positive modulations of the microbiota composition and metabolic activity. In particular, numbers of faecal bifidobacteria and lactobacilli were significantly higher when B-GOS juice was fermented compared to controls. Furthermore, fermentation of B-GOS juice resulted in an increase in Roseburia subcluster and concomitantly increased butyrate production, which is of potential benefit to the host. In conclusion, this study has shown B-GOS within orange juice can have a beneficial effect on the fecal microbiota. PMID:25807417
Costabile, Adele; Walton, Gemma E; Tzortzis, George; Vulevic, Jelena; Charalampopoulos, Dimitris; Gibson, Glenn R
2015-01-01
A three-stage continuous fermentative colonic model system was used to monitor in vitro the effect of different orange juice formulations on prebiotic activity. Three different juices with and without Bimuno, a GOS mixture containing galactooligosaccharides (B-GOS) were assessed in terms of their ability to induce a bifidogenic microbiota. The recipe development was based on incorporating 2.75g B-GOS into a 250 ml serving of juice (65°Brix of concentrate juice). Alongside the production of B-GOS juice, a control juice--orange juice without any additional Bimuno and a positive control juice, containing all the components of Bimuno (glucose, galactose and lactose) in the same relative proportions with the exception of B-GOS were developed. Ion Exchange Chromotography analysis was used to test the maintenance of bimuno components after the production process. Data showed that sterilisation had no significant effect on concentration of B-GOS and simple sugars. The three juice formulations were digested under conditions resembling the gastric and small intestinal environments. Main bacterial groups of the faecal microbiota were evaluated throughout the colonic model study using 16S rRNA-based fluorescence in situ hybridization (FISH). Potential effects of supplementation of the juices on microbial metabolism were studied measuring short chain fatty acids (SCFAs) using gas chromatography. Furthermore, B-GOS juices showed positive modulations of the microbiota composition and metabolic activity. In particular, numbers of faecal bifidobacteria and lactobacilli were significantly higher when B-GOS juice was fermented compared to controls. Furthermore, fermentation of B-GOS juice resulted in an increase in Roseburia subcluster and concomitantly increased butyrate production, which is of potential benefit to the host. In conclusion, this study has shown B-GOS within orange juice can have a beneficial effect on the fecal microbiota. PMID:25807417
NASA Astrophysics Data System (ADS)
Aggarwal, Gaurav
Because of their low density, high specific strength and high stiffness, titanium alloys are one of the prime candidates for structural application often requiring specific tribological properties. However, their relatively high friction coefficients and low wear resistance are limiting their application over a wider temperature range. Various coatings deposited with technologies like high velocity oxy flame (HVOF), detonation gun (DGun), electron beam physical vapor deposition (EB-PVD), etc., can improve wear performance and decrease corrosion damage. These technologies require high processing temperatures precluding the integration of thermally vulnerable lubricants. This research looks at a relatively new coating process called Cold Spray for self-lubricating coatings on Ti-6Al-4V alloys. Cold Spray can produce coatings without significant heating of the sprayed powder or substrate. The particles are in solid state as they hit the substrate, and the formation of coatings occurs mainly due to the kinetic energy of the particles. Therefore, the impact velocity plays an important role. Below a critical value, the particles can cause densification and abrasion of the substrate. The focus of this study is to design composite coatings for the cold spray process and determination of the critical velocity through finite element modeling. Different powders and feedstock formulation techniques are discussed in order to find an optimum formulation for self-lubricating coatings. A composite powder (Ni coated hBN) was found to be the best candidate for the feedstock. The deformation of composite particles upon impact on the substrate was modeled and compared to the experiments. A number of approaches involving different modeling platforms, particle-substrate geometries, and material models have been tried. This work presents the results of ANSYS (version 10.0) analysis using an axisymmetric model of the particle impact. Stress and strain distributions in the particle
Patil, Sushant; Suryavanshi, Shital; Pathak, Sulabha; Sharma, Shobhona; Patravale, Vandana
2013-10-15
The present investigation aims at formulating lipid based drug delivery system of β-Artemether and Lumefantrine and comparative pharmacological evaluation with innovator formulation. Commercial modified oil and indigenous natural fatty acids comprised the oily phase in developing lipidic formulation of β-Artemether and Lumefantrine. The developed system was characterized for mean globule size, stability by freeze thaw cycles, and birefringence. Developed formulation and innovator formulation were compared for their in vivo anti-malarial activity at different dose levels in male Swiss mice, infected with lethal ANKA strain of Plasmodium berghei. The percent parasitemia, activity against time and animal survival period were examined. On fourth day of antimalarial studies, at normal and ½ dose levels, formulations revealed zero percent parasitemia while control showed 33.92±6.00% parasitemia. At 1/10 dose level, developed and innovator formulations revealed zero percent parasitemia upto 11th day, however, three mice from innovator formulation demonstrated recrudescence after 12th day. Both the formulations at normal dose and ½ dose levels showed 100% activity and survival whereas at 1/10 dose level, innovator formulation showed, 62.5% survival. The developed lipidic system of β-Artemether and Lumefantrine exhibited excellent antimalarial activity with 100% survival. PMID:23886650
The VOL-CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation
NASA Astrophysics Data System (ADS)
Barsotti, S.; Neri, A.; Scire, J. S.
2008-03-01
We present a new modeling tool, named VOL-CALPUFF, that is able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely used in environmental applications of pollutant dispersion, that describes the dispersal process in both the proximal and distal regions and also in the presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 h. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, this paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper, Barsotti and Neri present a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) with the specific aim of comparing model predictions with independent observations.
Formulation of the Multi-Hit Model With a Non-Poisson Distribution of Hits
Vassiliev, Oleg N.
2012-07-15
Purpose: We proposed a formulation of the multi-hit single-target model in which the Poisson distribution of hits was replaced by a combination of two distributions: one for the number of particles entering the target and one for the number of hits a particle entering the target produces. Such an approach reflects the fact that radiation damage is a result of two different random processes: particle emission by a radiation source and interaction of particles with matter inside the target. Methods and Materials: Poisson distribution is well justified for the first of the two processes. The second distribution depends on how a hit is defined. To test our approach, we assumed that the second distribution was also a Poisson distribution. The two distributions combined resulted in a non-Poisson distribution. We tested the proposed model by comparing it with previously reported data for DNA single- and double-strand breaks induced by protons and electrons, for survival of a range of cell lines, and variation of the initial slopes of survival curves with radiation quality for heavy-ion beams. Results: Analysis of cell survival equations for this new model showed that they had realistic properties overall, such as the initial and high-dose slopes of survival curves, the shoulder, and relative biological effectiveness (RBE) In most cases tested, a better fit of survival curves was achieved with the new model than with the linear-quadratic model. The results also suggested that the proposed approach may extend the multi-hit model beyond its traditional role in analysis of survival curves to predicting effects of radiation quality and analysis of DNA strand breaks. Conclusions: Our model, although conceptually simple, performed well in all tests. The model was able to consistently fit data for both cell survival and DNA single- and double-strand breaks. It correctly predicted the dependence of radiation effects on parameters of radiation quality.
Zacharof, A I; Butler, A P
2004-01-01
A mathematical model simulating the hydrological and biochemical processes occurring in landfilled waste is presented and demonstrated. The model combines biochemical and hydrological models into an integrated representation of the landfill environment. Waste decomposition is modelled using traditional biochemical waste decomposition pathways combined with a simplified methodology for representing the rate of decomposition. Water flow through the waste is represented using a statistical velocity model capable of representing the effects of waste heterogeneity on leachate flow through the waste. Given the limitations in data capture from landfill sites, significant emphasis is placed on improving parameter identification and reducing parameter requirements. A sensitivity analysis is performed, highlighting the model's response to changes in input variables. A model test run is also presented, demonstrating the model capabilities. A parameter perturbation model sensitivity analysis was also performed. This has been able to show that although the model is sensitive to certain key parameters, its overall intuitive response provides a good basis for making reasonable predictions of the future state of the landfill system. Finally, due to the high uncertainty associated with landfill data, a tool for handling input data uncertainty is incorporated in the model's structure. It is concluded that the model can be used as a reasonable tool for modelling landfill processes and that further work should be undertaken to assess the model's performance. PMID:15120429
Dynamic formulation of thickened flame model for LES of premixed turbulent combustion.
NASA Astrophysics Data System (ADS)
Meneveau, C.; Nottin, C.; Veynante, D.
2000-11-01
As demonstrated in Colin et al. (Phys. Fluids 12, p. 1843, 2000) the thickened flame model for LES of premixed combustion (TFLES) has a number of attractive features such as correct asymptotics in the limit of DNS, in the case of a thickened laminar, steady flame, etc.. For the general case of turbulent, unsteady and curved, premixed flames, the model requires empirical parameters to be specified. With the aim of decreasing the dependence on empirical parameters, the dynamic procedure is applied to this problem. We find that the traditional application of the Germano identity, which seeks undetermined multiplicative model coefficients, fails because of a trivial cancellation of the coefficients when inserted in the Germano identity. We suggest that this is a general problem when applying the dynamic model to phenomena that occur at very disparate length-scales (here the true reaction occurs in a region which is typically much thinner than the LES grid-size). On the other hand, we find that the dynamic procedure is well-posed when searching for unknown scaling exponents (instead of coefficients). A new power-law formulation of dynamic TFLES is developed, and tested using a fully compressible, sixth-order finite-difference code (NTMIX). Applications to several cases are discussed: (a) 1-D laminar flame, (b) laminar flame-vortex interaction, and (c) flame propagation through 2-D decaying isotropic turbulence.
A revised land surface parameterization (SiB2) for atmospheric GCMs. Part I: Model formulation
Sellers, P.J.; Collatz, G.J.
1996-04-01
The formulation of a revised land surface parameterization for use within atmospheric general circulation models (GCMs) is presented. The model (SiB2) incorporates several significant improvements over the first version of the Simple Biosphere model (SiB) described in Sellers et al. The improvements can be summarized as follows: (1) incorporation of a realistic canopy photosynthesis-conductance model to describe the simultaneous transfer of CO{sub 2} and water vapor into and out of the vegetation, respectively; (2) use of satellite data, as described in a companion paper, Part II, to describe the vegetation phenology; (3) modification of the hydrological submodel to give better descriptions of baseflows and a more reliable calculation of interlayer exchanges within the soil profile; (4) incorporation of a {open_quotes}patchy{close_quotes} snowmelt treatment, which prevents rapid thermal and surface reflectance transitions when the area-zveraged snow cover is low and decreasing. To accommodate the changes in (1) and (2) above, the original two-layer vegetation canopy structure of SiB1 has been reduced to a single layer in SiB2. The use of satellite data in SiB2 and the performance of SiB2 when coupled to a GCM are described in the two companion papers. 68 refs., 7 figs., 4 tabs.
NASA Technical Reports Server (NTRS)
Belcastro, Christine M.; Chang, B.-C.; Fischl, Robert
1989-01-01
In the design and analysis of robust control systems for uncertain plants, the technique of formulating what is termed an M-delta model has become widely accepted and applied in the robust control literature. The M represents the transfer function matrix M(s) of the nominal system, and delta represents an uncertainty matrix acting on M(s). The uncertainty can arise from various sources, such as structured uncertainty from parameter variations or multiple unstructured uncertainties from unmodeled dynamics and other neglected phenomena. In general, delta is a block diagonal matrix, and for real parameter variations the diagonal elements are real. As stated in the literature, this structure can always be formed for any linear interconnection of inputs, outputs, transfer functions, parameter variations, and perturbations. However, very little of the literature addresses methods for obtaining this structure, and none of this literature addresses a general methodology for obtaining a minimal M-delta model for a wide class of uncertainty. Since have a delta matrix of minimum order would improve the efficiency of structured singular value (or multivariable stability margin) computations, a method of obtaining a minimal M-delta model would be useful. A generalized method of obtaining a minimal M-delta structure for systems with real parameter variations is given.
Salloum, Maher; Knio, Omar M.
2010-06-15
A transient multidimensional reduced model is constructed for the simulation of reaction fronts in Ni/Al multilayers. The formulation is based on the generalization of earlier methodologies developed for quasi-1D axial and normal propagation, specifically by adapting the reduced formalism for atomic mixing and heat release. This approach enables us to focus on resolving the thermal front structure, whose evolution is governed by thermal diffusion and heat release. A mixed integration scheme is used for this purpose, combining an extended-stability, Runge-Kutta-Chebychev (RKC) integration of the diffusion term with exact treatment of the chemical source term. Thus, a detailed description of atomic mixing within individual layers is avoided, which enables transient modeling of the reduced equations of motion in multiple dimensions. Two-dimensional simulations are first conducted of front propagation in composites combining two bilayer periods. Results are compared with the experimental measurements of Knepper et al., which reveal that the reaction velocity can depend significantly on layering frequency. The comparison indicates that, using a concentration-dependent conductivity model, the transient 2D computations can reasonably reproduce the experimental behavior. Additional tests are performed based on 3D computations of surface initiated reactions. Comparison of computed predictions with laser ignition measurements indicates that the computations provide reasonable estimates of ignition thresholds. A detailed discussion is finally provided of potential generalizations and associated hurdles. (author)
The integrated Earth System Model (iESM): formulation and functionality
Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; et al
2015-01-21
The integrated Earth System Model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM projectmore » integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.« less
The integrated Earth System Model (iESM): formulation and functionality
NASA Astrophysics Data System (ADS)
Collins, W. D.; Craig, A. P.; Truesdale, J. E.; Di Vittorio, A. V.; Jones, A. D.; Bond-Lamberty, B.; Calvin, K. V.; Edmonds, J. A.; Kim, S. H.; Thomson, A. M.; Patel, P.; Zhou, Y.; Mao, J.; Shi, X.; Thornton, P. E.; Chini, L. P.; Hurtt, G. C.
2015-01-01
The integrated Earth System Model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human-Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human-Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.
NASA Technical Reports Server (NTRS)
Connelly, L. C.
1977-01-01
The mission planning processor is a user oriented tool for consumables management and is part of the total consumables subsystem management concept. The approach to be used in developing a working model of the mission planning processor is documented. The approach includes top-down design, structured programming techniques, and application of NASA approved software development standards. This development approach: (1) promotes cost effective software development, (2) enhances the quality and reliability of the working model, (3) encourages the sharing of the working model through a standard approach, and (4) promotes portability of the working model to other computer systems.
NASA Astrophysics Data System (ADS)
Souza, S. R.; Carlson, B. V.; Donangelo, R.; Lynch, W. G.; Tsang, M. B.
2013-07-01
The generalized Fermi breakup model, recently demonstrated to be formally equivalent to the statistical multifragmentation model, if the contribution of excited states is included in the state densities of the former, is implemented. Because this treatment requires application of the statistical multifragmentation model repeatedly on hot fragments until they have decayed to their ground states, it becomes extremely computationally demanding, making its application to the systems of interest extremely difficult. Based on exact recursion formulas previously developed by Chase and Mekjian to calculate statistical weights very efficiently, we present an implementation which is efficient enough to allow it to be applied to large systems at high excitation energies. Comparison with the gemini++ sequential decay code and the Weisskopf-Ewing evaporation model shows that the predictions obtained with our treatment are fairly similar to those obtained with these more traditional models.
Improved Stability of a Model IgG3 by DoE-Based Evaluation of Buffer Formulations
Chavez, Brittany K.; Agarabi, Cyrus D.; Read, Erik K.; Boyne II, Michael T.; Khan, Mansoor A.; Brorson, Kurt A.
2016-01-01
Formulating appropriate storage conditions for biopharmaceutical proteins is essential for ensuring their stability and thereby their purity, potency, and safety over their shelf-life. Using a model murine IgG3 produced in a bioreactor system, multiple formulation compositions were systematically explored in a DoE design to optimize the stability of a challenging antibody formulation worst case. The stability of the antibody in each buffer formulation was assessed by UV/VIS absorbance at 280 nm and 410 nm and size exclusion high performance liquid chromatography (SEC) to determine overall solubility, opalescence, and aggregate formation, respectively. Upon preliminary testing, acetate was eliminated as a potential storage buffer due to significant visible precipitate formation. An additional 24 full factorial DoE was performed that combined the stabilizing effect of arginine with the buffering capacity of histidine. From this final DoE, an optimized formulation of 200 mM arginine, 50 mM histidine, and 100 mM NaCl at a pH of 6.5 was identified to substantially improve stability under long-term storage conditions and after multiple freeze/thaw cycles. Thus, our data highlights the power of DoE based formulation screening approaches even for challenging monoclonal antibody molecules. PMID:27042659
Improved Stability of a Model IgG3 by DoE-Based Evaluation of Buffer Formulations.
Chavez, Brittany K; Agarabi, Cyrus D; Read, Erik K; Boyne, Michael T; Khan, Mansoor A; Brorson, Kurt A
2016-01-01
Formulating appropriate storage conditions for biopharmaceutical proteins is essential for ensuring their stability and thereby their purity, potency, and safety over their shelf-life. Using a model murine IgG3 produced in a bioreactor system, multiple formulation compositions were systematically explored in a DoE design to optimize the stability of a challenging antibody formulation worst case. The stability of the antibody in each buffer formulation was assessed by UV/VIS absorbance at 280 nm and 410 nm and size exclusion high performance liquid chromatography (SEC) to determine overall solubility, opalescence, and aggregate formation, respectively. Upon preliminary testing, acetate was eliminated as a potential storage buffer due to significant visible precipitate formation. An additional 2(4) full factorial DoE was performed that combined the stabilizing effect of arginine with the buffering capacity of histidine. From this final DoE, an optimized formulation of 200 mM arginine, 50 mM histidine, and 100 mM NaCl at a pH of 6.5 was identified to substantially improve stability under long-term storage conditions and after multiple freeze/thaw cycles. Thus, our data highlights the power of DoE based formulation screening approaches even for challenging monoclonal antibody molecules. PMID:27042659
Formulation and quantization of a generalized model related to the chiral Schwinger model
NASA Astrophysics Data System (ADS)
Bracken, Paul
2009-07-01
A generalized theory which describes fermions interacting with a gauge field is investigated. In 1 + 1 dimensions such a model is equivalent to a theory in which a boson field appears in the Lagrangian density rather than a fermion field. In this form, the Lagrangian density can be diagonalized and then quantized in terms of the transformed fields. The case of the chiral Schwinger model can be obtained from the general model and the physics with respect to the operator form is discussed. It is shown how the theory can be made nonanomalous by means of a Wess-Zumino field.
GFDL's CM2 global coupled climate models. Part I: Formulation and simulation characteristics
Delworth, T.L.; Broccoli, A.J.; Rosati, A.; Stouffer, R.J.; Balaji, V.; Beesley, J.A.; Cooke, W.F.; Dixon, K.W.; Dunne, J.; Dunne, K.A.; Durachta, J.W.; Findell, K.L.; Ginoux, P.; Gnanadesikan, A.; Gordon, C.T.; Griffies, S.M.; Gudgel, R.; Harrison, M.J.; Held, I.M.; Hemler, R.S.; Horowitz, L.W.; Klein, S.A.; Knutson, T.R.; Kushner, P.J.; Langenhorst, A.R.; Lee, H.-C.; Lin, S.-J.; Lu, J.; Malyshev, S.L.; Milly, P.C.D.; Ramaswamy, V.; Russell, J.; Schwarzkopf, M.D.; Shevliakova, E.; Sirutis, J.J.; Spelman, M.J.; Stern, W.F.; Winton, M.; Wittenberg, A.T.; Wyman, B.; Zeng, F.; Zhang, R.
2006-01-01
The formulation and simulation characteristics of two new global coupled climate models developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) are described. The models were designed to simulate atmospheric and oceanic climate and variability from the diurnal time scale through multicentury climate change, given our computational constraints. In particular, an important goal was to use the same model for both experimental seasonal to interannual forecasting and the study of multicentury global climate change, and this goal has been achieved. Tw o versions of the coupled model are described, called CM2.0 and CM2.1. The versions differ primarily in the dynamical core used in the atmospheric component, along with the cloud tuning and some details of the land and ocean components. For both coupled models, the resolution of the land and atmospheric components is 2?? latitude ?? 2.5?? longitude; the atmospheric model has 24 vertical levels. The ocean resolution is 1?? in latitude and longitude, with meridional resolution equatorward of 30?? becoming progressively finer, such that the meridional resolution is 1/3?? at the equator. There are 50 vertical levels in the ocean, with 22 evenly spaced levels within the top 220 m. The ocean component has poles over North America and Eurasia to avoid polar filtering. Neither coupled model employs flux adjustments. The co ntrol simulations have stable, realistic climates when integrated over multiple centuries. Both models have simulations of ENSO that are substantially improved relative to previous GFDL coupled models. The CM2.0 model has been further evaluated as an ENSO forecast model and has good skill (CM2.1 has not been evaluated as an ENSO forecast model). Generally reduced temperature and salinity biases exist in CM2.1 relative to CM2.0. These reductions are associated with 1) improved simulations of surface wind stress in CM2.1 and associated changes in oceanic gyre circulations; 2) changes in cloud tuning and
Modeling flow in wetlands and underlying aquifers using a discharge potential formulation
NASA Astrophysics Data System (ADS)
Gusyev, M. A.; Haitjema, H. M.
2011-09-01
SummaryAn accurate assessment of water and nutrient balances in large scale wetland systems such as the Florida Everglades requires conjunctive modeling of surface water flow in wetlands and groundwater flow in underlying aquifers. Earlier work was based on the finite difference code MODFLOW with a special "wetlands package." This model treats the wetland flow as laminar with a very high transmissivity that is proportional to the wetland water depth cubed. However, these MODFLOW solutions appear sensitive to this highly non-linear wetland transmissivity, particularly under conditions of low vegetation density when the model may fail to converge. We propose to formulate the governing differential equation in terms of a discharge potential instead of potentiometric heads as done in MODFLOW, but otherwise using the same assumptions as in its wetlands package. We tested our approach on a few cases of one- and two-dimensional flow, both with a constant and a varying wetland bottom elevation. For the latter the discharge potential represents an irrotational part of the flow field which is combined with a component of the flow field that contains the curl. We found that both the robustness and the accuracy of the solution in terms of potentials was superior to the solution in terms of heads. In some cases the latter solution failed altogether, even for simple one-dimensional flow. We applied our method to model the effects of wetland hydrology on the nutrient redistribution in and near tree islands. We found that the subtle velocity distributions near these tree islands, as resulted from our conjunctive wetlands and groundwater flow solution, could help explain the increased nutrient depositions at these islands, particularly at the head of the islands, where, consequently, most of the vegetation occurs.
Non-spherical source-surface model of the heliosphere: a scalar formulation
NASA Astrophysics Data System (ADS)
Schulz, M.
1997-11-01
The source-surface method offers an alternative to full MHD simulation of the heliosphere. It entails specification of a surface from which the solar wind flows normally outward along straight lines. Compatibility with MHD results requires this (source) surface to be non-spherical in general and prolate (aligned with the solar dipole axis) in prototypical axisymmetric cases. Mid-latitude features on the source surface thus map to significantly lower latitudes in the heliosphere. The model is usually implemented by deriving the B field (in the region surrounded by the source surface) from a scalar potential formally expanded in spherical harmonics, with coefficients chosen so as to minimize the mean-square tangential component of B over this surface. In the simplified (scalar) version the quantity minimized is instead the variance of the scalar potential over the source surface. The scalar formulation greatly reduces the time required to compute required matrix elements, while imposing essentially the same physical boundary condition as the vector formulation (viz., that the coronal magnetic field be, as nearly as possible, normal to the source surface for continuity with the heliosphere). The source surface proposed for actual application is a surface of constant F equivr-kB , where r is the heliocentric distance and B is the scalar magnitude of the B field produced by currents inside the Sun. Comparison with MHD simulations suggests that kapprox1.4 is a good choice for the adjustable exponent. This value has been shown to map the neutral line on the source surface during Carrington Rotation 1869 (May-June 1993) to a range of latitudes that would have just grazed the position of Ulysses during that month in which sector structure disappeared from Ulysses' magnetometer observations. model has been based
Monforti, F; Vitali, L; Bellasio, R; Bianconi, R
2006-02-21
In this paper a new approach to photochemical modeling is investigated and a lagrangian particle model named Photochemical Lagrangian Particle Model (PLPM) is described. Lagrangian particle models are a consolidated tool to deal with the dispersion of pollutants in the atmosphere. Good results have been obtained dealing with inert pollutants. In recent years, a number of pioneering works have shown as Lagrangian models can be of great interest when dealing with photochemistry, provided that special care is given in the reconstruction of chemicals concentration in the atmosphere. Density reconstruction can be performed through the so called ''box counting'' method: an Eulerian grid for chemistry is introduced and density is computed counting particles in each box. In this way one of the main advantages of the Lagrangian approach, the grid independence, is lost. Photochemical reactions are treated in PLPM by means of the complex chemical mechanism SAPRC90 and four density reconstruction methods have been developed, based on the kernel density estimator approach, in order to obtain grid-free accurate concentrations. These methods are all fully grid-free but they differ each other in considering local or global features of the particles distribution, in treating the Cartesian directions separately or together and in being based on receptors or particles positions in space.
NASA Technical Reports Server (NTRS)
Bielawa, Richard L.
1988-01-01
In response to a systematic methodology assessment program directed to the aeroelastic stability of hingeless helicopter rotor blades, improved basic aeroelastic reformulations and new formulations relating to structural sweep were achieved. Correlational results are presented showing the substantially improved performance of the G400 aeroelastic analysis incorporating these new formulations. The formulations pertain partly to sundry solutions to classic problem areas, relating to dynamic inflow with vortex-ring state operation and basic blade kinematics, but mostly to improved physical modeling of elastic axis offset (structural sweep) in the presence of nonlinear structural twist. Specific issues addressed are an alternate modeling of the delta EI torsional excitation due to compound bending using a force integration approach, and the detailed kinematic representation of an elastically deflected point mass of a beam with both structural sweep and nonlinear twist.
A Simplified Land Model (SLM) for use in cloud-resolving models: Formulation and evaluation
NASA Astrophysics Data System (ADS)
Lee, Jungmin M.; Khairoutdinov, Marat
2015-09-01
A Simplified Land Model (SLM) that uses a minimalist set of parameters with a single-layer vegetation and multilevel soil structure has been developed distinguishing canopy and undercanopy energy budgets. The primary motivation has been to design a land model for use in the System for Atmospheric Modeling (SAM) cloud-resolving model to study land-atmosphere interactions with a sufficient level of realism. SLM uses simplified expressions for the transport of heat, moisture, momentum, and radiation in soil-vegetation system. The SLM performance has been evaluated over several land surface types using summertime tower observations of micrometeorological and biophysical data from three AmeriFlux sites, which include grassland, cropland, and deciduous-broadleaf forest. In general, the SLM captures the observed diurnal cycle of surface energy budget and soil temperature reasonably well, although reproducing the evolution of soil moisture, especially after rain events, has been challenging. The SLM coupled to SAM has been applied to the case of summertime shallow cumulus convection over land based on the Atmospheric Radiation Measurements (ARM) Southern Great Plain (SGP) observations. The simulated surface latent and sensible heat fluxes as well as the evolution of thermodynamic profiles in convective boundary layer agree well with the estimates based on the observations. Sensitivity of atmospheric boundary layer development to the soil moisture and different land cover types has been also examined.
NASA Astrophysics Data System (ADS)
Smits, Kathleen M.; Ngo, Viet V.; Cihan, Abdullah; Sakaki, Toshihiro; Illangasekare, Tissa H.
2012-12-01
Bare soil evaporation is a key process for water exchange between the land and the atmosphere and an important component of the water balance. However, there is no agreement on the best modeling methodology to determine evaporation under different atmospheric boundary conditions. Also, there is a lack of directly measured soil evaporation data for model validation to compare these methods to establish the validity of their mathematical formulations. Thus, a need exists to systematically compare evaporation estimates using existing methods to experimental observations. The goal of this work is to test different conceptual and mathematical formulations that are used to estimate evaporation from bare soils to critically investigate various formulations and surface boundary conditions. Such a comparison required the development of a numerical model that has the ability to incorporate these boundary conditions. For this model, we modified a previously developed theory that allows nonequilibrium liquid/gas phase change with gas phase vapor diffusion to better account for dry soil conditions. Precision data under well-controlled transient heat and wind boundary conditions were generated, and results from numerical simulations were compared with experimental data. Results demonstrate that the approaches based on different boundary conditions varied in their ability to capture different stages of evaporation. All approaches have benefits and limitations, and no one approach can be deemed most appropriate for every scenario. Comparisons of different formulations of the surface boundary condition validate the need for further research on heat and vapor transport processes in soil for better modeling accuracy.
Electromagnetic modeling of REBCO high field coils by the H-formulation
NASA Astrophysics Data System (ADS)
Xia, Jing; Bai, Hongyu; Lu, Jun; Gavrilin, Andrew V.; Zhou, Youhe; Weijers, Hubertus W.
2015-12-01
In this paper, we employ the anisotropic bulk approximation to successfully implement the electromagnetic modeling of superconducting coils wound with rare-earth-barium-copper-oxide (REBCO) tapes based on the H-formulation, in which the field-dependent critical current density and highly nonlinear E-J characteristic are considered. The total number of turns in the stacks of REBCO pancake coils is up to several thousand. We validate the anisotropic bulk model by comparing the ac loss of a small four-pancake coil between the bulk model and the original model which takes the actual thickness of the superconducting layer into account. Then, the anisotropic bulk model is used to investigate the self-field problem of the REBCO prototype coils of the National High Magnetic Field Laboratory 32 {{T}} all-superconducting magnet. The field and current density distributions are obtained, and an obvious shielding effect is observed at the top and bottom of the coils. The ac losses in the first and second cycles are calculated. The former is crucial to the design of the cooling system and the latter relates to the routine consumption of the liquid helium. It is found that the ac loss in the first cycle is 2.6 times as large as that in the second cycle. We also study the ac loss dependences on some key parameters (the critical current, n-value and ramp rate of the applied current). It is found that both in the first and second cycles, the ac loss increases with decreasing critical current. Moreover, the influence of the n-value on the ac loss is negligible. In addition, the ac loss decreases logarithmically with increasing ramp rate. However, the average power loss increases linearly with increasing ramp rate. We also compare some analytical estimates with the simulation result for the ac loss of the dual prototype coils. It is found that the results of Bean’s slab model are closer to the simulation result. The presented model is a useful tool to help us understand
Becker, D; Rigassi, T; Bauer-Brandl, A
1997-01-01
Abstract Based on an analysis of model granulates and tablets, a comparison was made of the effectiveness of the binders PVP K30 PH, Cellulose HP-M 603, Lycatab DSH, Lycatab PGS, and L-HPC (type LH 11). A high shear mixer was used to prepare two model granulates (placebo and paracetamol) under processing conditions which were, as far as possible, comparable. The binders were added as proportions of 2%, 6%, and 10%. Water was used as the granulating liquid. The properties of the placebo granulates (particle size distribution, bulk and tapped density, granule strength, flow properties), and those of the tablets (crushing strength, friability) prepared from these granulates under different compaction forces, were generally good. However, with PVP, Cellulose HP-M603, and Lycatab, the disintegration time of the tablets did not meet pharmacopoeial requirements even though a "disintegrant" was used in the "outer phase." The paracetamol formulations were prime examples of high-dose drug substances with particularly poor granulating and tabletting properties, well suited to reveal differences between the binders. The paracetamol granulates were of higher friability and less flowability than the placebo granulates. The tablets tended to cap, friability was (with few exceptions) high, and disintegration times were long. In the preparation of model tablets containing paracetamol, PVP K30 PH (6%). and Cellulose HP-M 603 (6%) turn out to be the binders of choice with respect to crushing strength, but the disintegration times are too long. Lycatab PGS, Lycatab DSH, and L-HPC-LH 11 could not be used to produce paracetamol tablets that met the requirements. PMID:24359330
NASA Astrophysics Data System (ADS)
Alessi, Roberto; Pham, Kim
2016-02-01
This paper presents a variational framework for the three-dimensional macroscopic modelling of superelastic shape memory alloys in an isothermal setting. Phase transformation is accounted through a unique second order tensorial internal variable, acting as the transformation strain. Postulating the total strain energy density as the sum of a free energy and a dissipated energy, the model depends on two material scalar functions of the norm of the transformation strain and a material scalar constant. Appropriate calibration of these material functions allows to render a wide range of constitutive behaviours including stress-softening and stress-hardening. The quasi-static evolution problem of a domain is formulated in terms of two physical principles based on the total energy of the system: a stability criterion, which selects the local minima of the total energy, and an energy balance condition, which ensures the consistency of the evolution of the total energy with respect to the external loadings. The local phase transformation laws in terms of Kuhn-Tucker relations are deduced from the first-order stability condition and the energy balance condition. The response of the model is illustrated with a numerical traction-torsion test performed on a thin-walled cylinder. Evolutions of homogeneous states are given for proportional and non-proportional loadings. Influence of the stress-hardening/softening properties on the evolution of the transformation domain is emphasized. Finally, in view of an identification process, the issue of stability of homogeneous states in a multi-dimensional setting is answered based on the study of second-order derivative of the total energy. Explicit necessary and sufficient conditions of stability are provided.
NASA Technical Reports Server (NTRS)
Sohn, J. L.; Heinrich, J. C.
1990-01-01
The calculation of pressures when the penalty-function approximation is used in finite-element solutions of laminar incompressible flows is addressed. A Poisson equation for the pressure is formulated that involves third derivatives of the velocity field. The second derivatives appearing in the weak formulation of the Poisson equation are calculated from the C0 velocity approximation using a least-squares method. The present scheme is shown to be efficient, free of spurious oscillations, and accurate. Examples of applications are given and compared with results obtained using mixed formulations.
Glacial isostatic adjustment on 3-D Earth models: a finite-volume formulation
NASA Astrophysics Data System (ADS)
Latychev, Konstantin; Mitrovica, Jerry X.; Tromp, Jeroen; Tamisiea, Mark E.; Komatitsch, Dimitri; Christara, Christina C.
2005-05-01
We describe and present results from a finite-volume (FV) parallel computer code for forward modelling the Maxwell viscoelastic response of a 3-D, self-gravitating, elastically compressible Earth to an arbitrary surface load. We implement a conservative, control volume discretization of the governing equations using a tetrahedral grid in Cartesian geometry and a low-order, linear interpolation. The basic starting grid honours all major radial discontinuities in the Preliminary Reference Earth Model (PREM), and the models are permitted arbitrary spatial variations in viscosity and elastic parameters. These variations may be either continuous or discontinuous at a set of grid nodes forming a 3-D surface within the (regional or global) modelling domain. In the second part of the paper, we adopt the FV methodology and a spherically symmetric Earth model to generate a suite of predictions sampling a broad class of glacial isostatic adjustment (GIA) data types (3-D crustal motions, long-wavelength gravity anomalies). These calculations, based on either a simple disc load history or a global Late Pleistocene ice load reconstruction (ICE-3G), are benchmarked against predictions generated using the traditional normal-mode approach to GIA. The detailed comparison provides a guide for future analyses (e.g. what grid resolution is required to obtain a specific accuracy?) and it indicates that discrepancies in predictions of 3-D crustal velocities less than 0.1 mm yr-1 are generally obtainable for global grids with ~3 × 106 nodes; however, grids of higher resolution are required to predict large-amplitude (>1 cm yr-1) radial velocities in zones of peak post-glacial uplift (e.g. James bay) to the same level of absolute accuracy. We conclude the paper with a first application of the new formulation to a 3-D problem. Specifically, we consider the impact of mantle viscosity heterogeneity on predictions of present-day 3-D crustal motions in North America. In these tests, the
NASA Astrophysics Data System (ADS)
Cimorelli, Alan J.; Perry, Steven G.; Venkatram, Akula; Weil, Jeffrey C.; Paine, Robertj.; Wilson, Robert B.; Lee, Russell F.; Peters, Warren D.; Brode, Roger W.
2005-05-01
The formulation of the American Meteorological Society (AMS) and U.S. Environmental Protection Agency (EPA) Regulatory Model (AERMOD) Improvement Committee's applied air dispersion model is described. This is the first of two articles describing the model and its performance. Part I includes AERMOD's characterization of the boundary layer with computation of the Monin-Obukhov length, surface friction velocity, surface roughness length, sensible heat flux, convective scaling velocity, and both the shear- and convection-driven mixing heights. These parameters are used in conjunction with meteorological measurements to characterize the vertical structure of the wind, temperature, and turbulence. AERMOD's method for considering both the vertical inhomogeneity of the meteorological characteristics and the influence of terrain are explained. The model's concentration estimates are based on a steady-state plume approach with significant improvements over commonly applied regulatory dispersion models. Complex terrain influences are provided by combining a horizontal plume state and a terrain-following state. Dispersion algorithms are specified for convective and stable conditions, urban and rural areas, and in the influence of buildings and other structures. Part II goes on to describe the performance of AERMOD against 17 field study databases.
Bugeanu, Monica; Di Remigio, Roberto; Mozgawa, Krzysztof; Reine, Simen Sommerfelt; Harbrecht, Helmut; Frediani, Luca
2015-12-21
The simplicity of dielectric continuum models has made them a standard tool in almost any Quantum Chemistry (QC) package. Despite being intuitive from a physical point of view, the actual electrostatic problem at the cavity boundary is challenging: the underlying boundary integral equations depend on singular, long-range operators. The parametrization of the cavity boundary should be molecular-shaped, smooth and differentiable. Even the most advanced implementations, based on the integral equation formulation (IEF) of the polarizable continuum model (PCM), generally lead to working equations which do not guarantee convergence to the exact solution and/or might become numerically unstable in the limit of large refinement of the molecular cavity (small tesserae). This is because they generally make use of a surface parametrization with cusps (interlocking spheres) and employ collocation methods for the discretization (point charges). Wavelets on a smooth cavity are an attractive alternative to consider: for the operators involved, they lead to highly sparse matrices and precise error control. Moreover, by making use of a bilinear basis for the representation of operators and functions on the cavity boundary, all equations can be differentiated to enable the computation of geometrical derivatives. In this contribution, we present our implementation of the IEFPCM with bilinear wavelets on a smooth cavity boundary. The implementation has been carried out in our module PCMSolver and interfaced with LSDalton, demonstrating the accuracy of the method both for the electrostatic solvation energy and for linear response properties. In addition, the implementation in a module makes our framework readily available to any QC software with minimal effort. PMID:26256401
Townsend, Molly T; Sarigul-Klijn, Nesrin
2016-01-01
Simplified material models are commonly used in computational simulation of biological soft tissue as an approximation of the complicated material response and to minimize computational resources. However, the simulation of complex loadings, such as long-duration tissue swelling, necessitates complex models that are not easy to formulate. This paper strives to offer the updated Lagrangian formulation comprehensive procedure of various non-linear material models for the application of finite element analysis of biological soft tissues including a definition of the Cauchy stress and the spatial tangential stiffness. The relationships between water content, osmotic pressure, ionic concentration and the pore pressure stress of the tissue are discussed with the merits of these models and their applications. PMID:26611112
In silico modelling of drug–polymer interactions for pharmaceutical formulations
Ahmad, Samina; Johnston, Blair F.; Mackay, Simon P.; Schatzlein, Andreas G.; Gellert, Paul; Sengupta, Durba; Uchegbu, Ijeoma F.
2010-01-01
Selecting polymers for drug encapsulation in pharmaceutical formulations is usually made after extensive trial and error experiments. To speed up excipient choice procedures, we have explored coarse-grained computer simulations (dissipative particle dynamics (DPD) and coarse-grained molecular dynamics using the MARTINI force field) of polymer–drug interactions to study the encapsulation of prednisolone (log p = 1.6), paracetamol (log p = 0.3) and isoniazid (log p = −1.1) in poly(l-lactic acid) (PLA) controlled release microspheres, as well as the encapsulation of propofol (log p = 4.1) in bioavailability enhancing quaternary ammonium palmitoyl glycol chitosan (GCPQ) micelles. Simulations have been compared with experimental data. DPD simulations, in good correlation with experimental data, correctly revealed that hydrophobic drugs (prednisolone and paracetamol) could be encapsulated within PLA microspheres and predicted the experimentally observed paracetamol encapsulation levels (5–8% of the initial drug level) in 50 mg ml−1 PLA microspheres, but only when initial paracetamol levels exceeded 5 mg ml−1. However, the mesoscale technique was unable to model the hydrophilic drug (isoniazid) encapsulation (4–9% of the initial drug level) which was observed in experiments. Molecular dynamics simulations using the MARTINI force field indicated that the self-assembly of GCPQ is rapid, with propofol residing at the interface between micellar hydrophobic and hydrophilic groups, and that there is a heterogeneous distribution of propofol within the GCPQ micelle population. GCPQ–propofol experiments also revealed a population of relatively empty and drug-filled GCPQ particles. PMID:20519214
In silico modelling of drug-polymer interactions for pharmaceutical formulations.
Ahmad, Samina; Johnston, Blair F; Mackay, Simon P; Schatzlein, Andreas G; Gellert, Paul; Sengupta, Durba; Uchegbu, Ijeoma F
2010-08-01
Selecting polymers for drug encapsulation in pharmaceutical formulations is usually made after extensive trial and error experiments. To speed up excipient choice procedures, we have explored coarse-grained computer simulations (dissipative particle dynamics (DPD) and coarse-grained molecular dynamics using the MARTINI force field) of polymer-drug interactions to study the encapsulation of prednisolone (log p = 1.6), paracetamol (log p = 0.3) and isoniazid (log p = -1.1) in poly(L-lactic acid) (PLA) controlled release microspheres, as well as the encapsulation of propofol (log p = 4.1) in bioavailability enhancing quaternary ammonium palmitoyl glycol chitosan (GCPQ) micelles. Simulations have been compared with experimental data. DPD simulations, in good correlation with experimental data, correctly revealed that hydrophobic drugs (prednisolone and paracetamol) could be encapsulated within PLA microspheres and predicted the experimentally observed paracetamol encapsulation levels (5-8% of the initial drug level) in 50 mg ml(-1) PLA microspheres, but only when initial paracetamol levels exceeded 5 mg ml(-1). However, the mesoscale technique was unable to model the hydrophilic drug (isoniazid) encapsulation (4-9% of the initial drug level) which was observed in experiments. Molecular dynamics simulations using the MARTINI force field indicated that the self-assembly of GCPQ is rapid, with propofol residing at the interface between micellar hydrophobic and hydrophilic groups, and that there is a heterogeneous distribution of propofol within the GCPQ micelle population. GCPQ-propofol experiments also revealed a population of relatively empty and drug-filled GCPQ particles. PMID:20519214
NASA Astrophysics Data System (ADS)
Moore, Andrew M.; Arango, Hernan G.; Broquet, Gregoire; Powell, Brian S.; Weaver, Anthony T.; Zavala-Garay, Javier
2011-10-01
The Regional Ocean Modeling System (ROMS) is one of the few community ocean general circulation models for which a 4-dimensional variational data assimilation (4D-Var) capability has been developed. The ROMS 4D-Var capability is unique in that three variants of 4D-Var are supported: a primal formulation of incremental strong constraint 4D-Var (I4D-Var), a dual formulation based on a physical-space statistical analysis system (4D-PSAS), and a dual formulation representer-based variant of 4D-Var (R4D-Var). In each case, ROMS is used in conjunction with available observations to identify a best estimate of the ocean circulation based on a set of a priori hypotheses about errors in the initial conditions, boundary conditions, surface forcing, and errors in the model in the case of 4D-PSAS and R4D-Var. In the primal formulation of I4D-Var the search for the best circulation estimate is performed in the full space of the model control vector, while for the dual formulations of 4D-PSAS and R4D-Var only the sub-space of linear functions of the model state vector spanned by the observations (i.e. the dual space) is searched. In oceanographic applications, the number of observations is typically much less than the dimension of the model control vector, so there are clear advantages to limiting the search to the space spanned by the observations. In the case of 4D-PSAS and R4D-Var, the strong constraint assumption (i.e. that the model is error free) can be relaxed leading to the so-called weak constraint formulation. This paper describes the three aforementioned variants of 4D-Var as they are implemented in ROMS. Critical components that are common to each approach are conjugate gradient descent, preconditioning, and error covariance models, which are also described. Finally, several powerful 4D-Var diagnostic tools are discussed, namely computation of posterior errors, eigenvector analysis of the posterior error covariance, observation impact, and observation sensitivity.
Gupta, Y K; Katyal, Jatinder; Kumar, Gajendra; Mehla, Jogender; Katiyar, C K; Sharma, Naveen; Yadav, Satpal
2009-01-01
Cough is the most common symptom of respiratory diseases. When cough becomes serious, opioids are effective, but they have side effects like sedation, constipation, some addiction liability and also compromise the respiratory function. Therefore, there is need to have effective anti-tussive agent which do not have respiratory suppressant activity. The present study was carried out to evaluate anti-tussive activity of combination of herbal drugs as formulations in sulphur dioxide (SO2)-induced cough model in mice. Albino mice of either sex, weighing 25-30 g were divided into eight groups, (n = 6). Group 1 served as normal control, group 2 mice were given distilled water, group 3 was positive control and received codeine sulphate (10 mg/kg, p.o.) and group 4, 5, 6, 7 received coded 1 formulations 1, 2, 3 and 4 respectively at a dose of 0.3 ml/mice, orally, while group VIII was the vehicle control. Thirty minutes later, the mice were exposed to sulphur dioxide again for 45 sec. The mice were then placed in an observation chamber for counting of cough bouts, by two independent observers, for five minutes. All the formulations used showed significant antitussive activity in sulphur dioxide induced cough model. Thus, these formulations can prove to be useful for alleviating cough. PMID:19810578
NASA Astrophysics Data System (ADS)
Anderson, Thomas R.; Hessen, Dag O.; Mitra, Aditee; Mayor, Daniel J.; Yool, Andrew
2013-09-01
The performance of four contemporary formulations describing trophic transfer, which have strongly contrasting assumptions as regards the way that consumer growth is calculated as a function of food C:N ratio and in the fate of non-limiting substrates, was compared in two settings: a simple steady-state ecosystem model and a 3D biogeochemical general circulation model. Considerable variation was seen in predictions for primary production, transfer to higher trophic levels and export to the ocean interior. The physiological basis of the various assumptions underpinning the chosen formulations is open to question. Assumptions include Liebig-style limitation of growth, strict homeostasis in zooplankton biomass, and whether excess C and N are released by voiding in faecal pellets or via respiration/excretion post-absorption by the gut. Deciding upon the most appropriate means of formulating trophic transfer is not straightforward because, despite advances in ecological stoichiometry, the physiological mechanisms underlying these phenomena remain incompletely understood. Nevertheless, worrying inconsistencies are evident in the way in which fundamental transfer processes are justified and parameterised in the current generation of marine ecosystem models, manifested in the resulting simulations of ocean biogeochemistry. Our work highlights the need for modellers to revisit and appraise the equations and parameter values used to describe trophic transfer in marine ecosystem models.
Finite Formulation for Modeling Guided Wave Structures Embedded in a Lossy Half-Space
NASA Astrophysics Data System (ADS)
Heshmatzadeh, Maryam; Bridges, Greg E.
2010-04-01
A Finite Formulation technique, the Cell Method, is applied to a transmission line embedded in a complex medium. Cell Method is a Finite Formulation numerical technique that uses a primal-dual cell complex and global (integral) variables instead of field variables (densities). A new time-harmonic finite formulation using a non-orthogonal dual mesh is presented that is based on choosing incenters of primal triangles as an alternative to barycentric dual points. In the incentric formulation, diagonal constitutive matrices are obtained and an eigenvalue problem is solved in the first step (zero-order approximation). A minimization procedure is then utilized to efficiently improve the accuracy of the zero-order solution. In this paper the effect of the non-perfectly conducting earth on the propagation constant is investigated as the location of a bare (or insulated) conductor passes through the interface of a lossy half space. It is observed that the propagation constant depends on the burial depth when it is less than the skin depth in the earth. It is shown that analytical (thin wire-based) approximations for the above-ground and buried cases fail when the conductor is close to or partially embedded in the interface.
Kinnunen, Hanne M; Sharma, Vikas; Contreras-Rojas, Luis Rodrigo; Yu, Yafei; Alleman, Chlöe; Sreedhara, Alavattam; Fischer, Stefan; Khawli, Leslie; Yohe, Stefan T; Bumbaca, Daniela; Patapoff, Thomas W; Daugherty, Ann L; Mrsny, Randall J
2015-09-28
Subcutaneous (SC) injection is becoming a more common route for the administration of biopharmaceuticals. Currently, there is no reliable in vitro method that can be used to anticipate the in vivo performance of a biopharmaceutical formulation intended for SC injection. Nor is there an animal model that can predict in vivo outcomes such as bioavailability in humans. We address this unmet need by the development of a novel in vitro system, termed Scissor (Subcutaneous Injection Site Simulator). The system models environmental changes that a biopharmaceutical could experience as it transitions from conditions of a drug product formulation to the homeostatic state of the hypodermis following SC injection. Scissor uses a dialysis-based injection chamber, which can incorporate various concentrations and combinations of acellular extracellular matrix (ECM) components that may affect the release of a biopharmaceutical from the SC injection site. This chamber is immersed in a container of a bicarbonate-based physiological buffer that mimics the SC injection site and the infinite sink of the body. Such an arrangement allows for real-time monitoring of the biopharmaceutical within the injection chamber, and can be used to characterize physicochemical changes of the drug and its interactions with ECM components. Movement of a biopharmaceutical from the injection chamber to the infinite sink compartment simulates the drug migration from the injection site and uptake by the blood and/or lymph capillaries. Here, we present an initial evaluation of the Scissor system using the ECM element hyaluronic acid and test formulations of insulin and four different monoclonal antibodies. Our findings suggest that Scissor can provide a tractable method to examine the potential fate of a biopharmaceutical formulation after its SC injection in humans and that this approach may provide a reliable and representative alternative to animal testing for the initial screening of SC formulations
NASA Astrophysics Data System (ADS)
Huyakorn, P. S.; Panday, S.; Wu, Y. S.
1994-06-01
A three-dimensional, three-phase numerical model is presented for stimulating the movement on non-aqueous-phase liquids (NAPL's) through porous and fractured media. The model is designed for practical application to a wide variety of contamination and remediation scenarios involving light or dense NAPL's in heterogeneous subsurface systems. The model formulation is first derived for three-phase flow of water, NAPL and air (or vapor) in porous media. The formulation is then extended to handle fractured systems using the dual-porosity and discrete-fracture modeling approaches The model accommodates a wide variety of boundary conditions, including withdrawal and injection well conditions which are treated rigorously using fully implicit schemes. The three-phase of formulation collapses to its simpler forms when air-phase dynamics are neglected, capillary effects are neglected, or two-phase-air-liquid, liquid-liquid systems with one or two active phases are considered. A Galerkin procedure with upstream weighting of fluid mobilities, storage matrix lumping, and fully implicit treatment of nonlinear coefficients and well conditions is used. A variety of nodal connectivity schemes leading to finite-difference, finite-element and hybrid spatial approximations in three dimensions are incorporated in the formulation. Selection of primary variables and evaluation of the terms of the Jacobian matrix for the Newton-Raphson linearized equations is discussed. The various nodal lattice options, and their significance to the computational time and memory requirements with regards to the block-Orthomin solution scheme are noted. Aggressive time-stepping schemes and under-relaxation formulas implemented in the code further alleviate the computational burden.
Guerrero, Mariana; Carlone, Marco
2010-08-15
Purpose: In recent years, several models were proposed that modify the standard linear-quadratic (LQ) model to make the predicted survival curve linear at high doses. Most of these models are purely phenomenological and can only be applied in the particular case of acute doses per fraction. The authors consider a mechanistic formulation of a linear-quadratic-linear (LQL) model in the case of split-dose experiments and exponentially decaying sources. This model provides a comprehensive description of radiation response for arbitrary dose rate and fractionation with only one additional parameter. Methods: The authors use a compartmental formulation of the LQL model from the literature. They analytically solve the model's differential equations for the case of a split-dose experiment and for an exponentially decaying source. They compare the solutions of the survival fraction with the standard LQ equations and with the lethal-potentially lethal (LPL) model. Results: In the case of the split-dose experiment, the LQL model predicts a recovery ratio as a function of dose per fraction that deviates from the square law of the standard LQ. The survival fraction as a function of time between fractions follows a similar exponential law as the LQ but adds a multiplicative factor to the LQ parameter {beta}. The LQL solution for the split-dose experiment is very close to the LPL prediction. For the decaying source, the differences between the LQL and the LQ solutions are negligible when the half-life of the source is much larger than the characteristic repair time, which is the clinically relevant case. Conclusions: The compartmental formulation of the LQL model can be used for arbitrary dose rates and provides a comprehensive description of dose response. When the survival fraction for acute doses is linear for high dose, a deviation of the square law formula of the recovery ratio for split doses is also predicted.
Ramanathan, M; Balaji, B; Justin, A
2011-04-01
Perment, a polyherbal Ayurvedic formulation that contains equal parts of Clitoria ternatea Linn., Withania somnifera Dun., Asparagus racemosus Linn., Bacopa monniera Linn., is used clinically as mood elevators. The aim of the present study was to explore the behavioural effects and to understand possible mode of action of Perment in stress induced depressive model. Chronic unpredictable mild stress (CUMS) was used to induce depression in rats. Open field exploratory behaviour, elevated plus maze, social interaction and behavioural despair tests were used to assess behaviour. Using standard protocols plasma noradrenaline, serotonin, corticosterone and brain/adrenal corticosterone levels were measured to support the behavioural effects of Perment. Exposure to CUMS for 21 days caused anxiety and depression in rats, as indicated by significant decrease in locomotor activity in the open field exploratory behaviour test and increased immobility period in the behavioural despair test. Perment predominantly exhibited antidepressant action than anxiolytic activity. Further Perment increased the plasma noradrenaline and serotonin levels in stressed rats. No significant alteration in the brain corticosterone level in stressed rats was observed with Perment treatment. However the adrenal corticosterone level is decreased with Perment. It can be concluded that the Perment formulation exhibited synergistic activity, has a significant antidepressant and anxiolytic activity, which may be mediated through adrenergic and serotonergic system activation. Currently the formulation is clinically used as anxiolytic but the present results suggest that the formulation can also be indicated in patients affected with depression. PMID:21614890
ERIC Educational Resources Information Center
Markus, Keith A.
2008-01-01
One can distinguish statistical models used in causal modeling from the causal interpretations that align them with substantive hypotheses. Causal modeling typically assumes an efficient causal interpretation of the statistical model. Causal modeling can also make use of mereological causal interpretations in which the state of the parts…
Paul, M; Durand, R; Fessi, H; Rivollet, D; Houin, R; Astier, A; Deniau, M
1997-01-01
The efficacy of a new liposomal formulation of amphotericin B was compared to that of amphotericin B deoxycholate (Fungizone) in a murine model of visceral leishmaniasis induced by Leishmania infantum. Median effective doses (ED50) were determined with two different strains: strain 1 was obtained from an untreated patient, and strain 2 was obtained from a patient who had received 12.5 g of amphotericin B over 3 years. BALB/c mice were infected intravenously on day 0 with promastigotes and then treated on days 14, 16, and 18 (strain 1) or on days 21, 23, and 25 (strain 2) with the liposomal formulation of amphotericin B (five doses were tested for each strain: 0.05, 0.1, 0.5, 0.8, and 3 mg/kg of body weight) or with conventional amphotericin B (four doses were tested for each strain: 0.05, 0.1, 0.5, and 0.8 mg/kg). Mice in the control group received normal saline solution. The liposomal amphotericin B formulation was about three times more active than the conventional drug against both strains. ED50 of the liposomal formulation were 0.054 (strain 1) and 0.194 (strain 2) mg/kg. ED50 of conventional amphotericin B were 0.171 (strain 1) and 0.406 (strain 2) mg/kg. Determination of drug tissular levels, 3 days after the last drug administration, showed a drug accumulation in hepatic and splenic tissues much higher after administration of liposomal amphotericin B than after conventional amphotericin B. A lack of toxicity was noted in all groups treated with the liposomal formulation. PMID:9257750
Reddy, Micaela B; Connor, Alyson; Brennan, Barbara J; Morcos, Peter N; Zhou, Amy; McLawhon, Pamela; Fretland, Adrian; Evans, Philip; Smith, Patrick; Tran, Jonathan Q
2011-07-01
Danoprevir, a potent, selective inhibitor of HCV NS3/4A protease, has a short half-life in humans. Therefore, the feasibility of a controlled release (CR) formulation to allow less frequent dosing was investigated using experimental approaches and physiological modeling to examine whether danoprevir is absorbed in the colon. Danoprevir absorption was studied in portal-vein-cannulated monkeys and in monkeys surgically modified to make intraduodenal, intrajejunal, intracolonic and oral administration possible. In portal-vein-cannulated monkeys, absorption was apparent up to 24 h after administration. The observed relative bioavailability from intracolonic delivery in the monkey was approximately 30% relative to oral administration, consistent with the model prediction of 40%. Human relative bioavailability for a tablet delivered to the colon compared with an immediate release (IR) formulation was predicted to be 4-28%. Preclinical data and modeling suggested that CR development would be challenging for this Biopharmaceutics Classification System Class IV compound. Therefore, a confirmative study in healthy volunteers was conducted to investigate the relative bioavailability of danoprevir in various regions of the gastrointestinal tract. In a randomized, open-label, crossover study, subjects received 100 mg danoprevir IR soft gel capsule, 100 mg danoprevir solution delivered to the distal small bowel and colon via an Enterion™ capsule (a remotely activated capsule for regional drug delivery) and 100 mg danoprevir powder to the colon via an Enterion™ capsule. The relative bioavailability of danoprevir (compared with IR) delivered to the colon was 6.5% for a solution and 0.6% for a powder formulation, indicating that a CR formulation is not feasible. PMID:21660978
Sahana, H; Khajuria, Deepak Kumar; Razdan, Rema; Mahapatra, D Roy; Bhat, M R; Suresh, Sarasija; Rao, R Ramachandra; Mariappan, L
2013-02-01
A superior drug formulation capable of achieving efficient osteogenesis is in imperative demand for the treatment of osteoporosis. In the present study we investigated the potential of using novel risedronate-hydroxyapatite (HA) nanoparticle based formulation in an animal model of established osteoporosis. Nanoparticles of HA loaded with risedronate (NHLR) of various sizes (80-130 nm) were generated for bone targeted drug delivery. Three months after ovariectomy, 36 ovariectomized (OVX) rats were divided into 6 equal groups and treated with various doses of NHLR (500, 350 and 250 microg/kg intravenous single dose) and sodium risedronate (500 microg/kg, intravenous single dose). Untreated OVX and sham OVX served as controls. One month after drug administration, the left tibia and femur were tested for bone mechanical properties and histology, respectively. In the right femur, bone density was measured by method based on Archimedes principle and bone porosity analyses were performed using X-ray imaging. NHLR (250 microg/kg) showed a significant increase in bone density and reduced bone porosity when compared with OVX control. Moreover, NHLR (250 microg/kg) significantly increased bone mechanical properties and bone quality when compared with OVX control. The results strongly suggest that the NHLR, which is a novel nanoparticle based formulation, has a therapeutic advantage over risedronate sodium monotherapy for the treatment of osteoporosis in a rat model of postmenopausal osteoporosis. PMID:23627045
NASA Astrophysics Data System (ADS)
Wang, Mingyang; Zhang, Feifei; Song, Chao; Shi, Pengfei; Zhu, Jin
2016-07-01
Innovation in hypotheses is a key transformative driver for scientific development. The conventional centralized hypothesis formulation approach, where a dominant hypothesis is typically derived from a primary phenomenon, can, inevitably, impose restriction on the range of conceivable experiments and legitimate hypotheses, and ultimately impede understanding of the system of interest. We report herein the proposal of a decentralized approach for the formulation of hypotheses, through initial preconception-free phenomenon accumulation and subsequent reticular logical reasoning processes. The two-step approach can provide an unbiased, panoramic view of the system and as such should enable the generation of a set of more coherent and therefore plausible hypotheses. As a proof-of-concept demonstration of the utility of this open-ended approach, a hierarchical model has been developed for a prion self-assembled system, allowing insight into hitherto elusive static and dynamic features associated with this intriguing structure.
Wang, Mingyang; Zhang, Feifei; Song, Chao; Shi, Pengfei; Zhu, Jin
2016-01-01
Innovation in hypotheses is a key transformative driver for scientific development. The conventional centralized hypothesis formulation approach, where a dominant hypothesis is typically derived from a primary phenomenon, can, inevitably, impose restriction on the range of conceivable experiments and legitimate hypotheses, and ultimately impede understanding of the system of interest. We report herein the proposal of a decentralized approach for the formulation of hypotheses, through initial preconception-free phenomenon accumulation and subsequent reticular logical reasoning processes. The two-step approach can provide an unbiased, panoramic view of the system and as such should enable the generation of a set of more coherent and therefore plausible hypotheses. As a proof-of-concept demonstration of the utility of this open-ended approach, a hierarchical model has been developed for a prion self-assembled system, allowing insight into hitherto elusive static and dynamic features associated with this intriguing structure. PMID:27464832
Wang, Mingyang; Zhang, Feifei; Song, Chao; Shi, Pengfei; Zhu, Jin
2016-01-01
Innovation in hypotheses is a key transformative driver for scientific development. The conventional centralized hypothesis formulation approach, where a dominant hypothesis is typically derived from a primary phenomenon, can, inevitably, impose restriction on the range of conceivable experiments and legitimate hypotheses, and ultimately impede understanding of the system of interest. We report herein the proposal of a decentralized approach for the formulation of hypotheses, through initial preconception-free phenomenon accumulation and subsequent reticular logical reasoning processes. The two-step approach can provide an unbiased, panoramic view of the system and as such should enable the generation of a set of more coherent and therefore plausible hypotheses. As a proof-of-concept demonstration of the utility of this open-ended approach, a hierarchical model has been developed for a prion self-assembled system, allowing insight into hitherto elusive static and dynamic features associated with this intriguing structure. PMID:27464832
NASA Technical Reports Server (NTRS)
Maples, A. L.; Poirier, D. R.
1980-01-01
The physical and numerical formulation of a model for the horizontal solidification of a binary alloy is described. It can be applied in an ingot. The major purpose of the model is to calculate macrosegregation in a casting ingot which results from flow of interdendritic liquid during solidification. The flow, driven by solidification contractions and by gravity acting on density gradients in the interdendritic liquid, was modeled as flow through a porous medium. The symbols used are defined. The physical formulation of the problem leading to a set of equations which can be used to obtain: (1) the pressure field; (2) the velocity field: (3) mass flow and (4) solute flow in the solid plus liquid zone during solidification is presented. With these established, the model calculates macrosegregation after solidification is complete. The numerical techniques used to obtain solution on a computational grid are presented. Results, evaluation of the results, and recommendations for future development of the model are given. The macrosegregation and flow field predictions for tin-lead, aluminum-copper, and tin-bismuth alloys are included as well as comparisons of some of the predictions with published predictions or with empirical data.
NASA Astrophysics Data System (ADS)
Delmotte, Blaise; Climent, Eric; Plouraboué, Franck
2015-04-01
This contribution provides a general framework to use Lagrange multipliers for the simulation of low Reynolds number fiber dynamics based on Bead Models (BM). This formalism provides an efficient method to account for kinematic constraints. We illustrate, with several examples, to which extent the proposed formulation offers a flexible and versatile framework for the quantitative modeling of flexible fibers deformation and rotation in shear flow, the dynamics of actuated filaments and the propulsion of active swimmers. Furthermore, a new contact model called Gears Model is proposed and successfully tested. It avoids the use of numerical artifices such as repulsive forces between adjacent beads, a source of numerical difficulties in the temporal integration of previous Bead Models.
Ghabraie, Mina; Vu, Khanh Dang; Huq, Tanzina; Khan, Avik; Lacroix, Monique
2016-06-01
This study was conducted to evaluate the effects of sixteen antibacterial formulations against Listeria monocytogenes in a sausage model using a standard experimental design with 4 independent factors at 2 levels (2(4)). Four independent factors consisted of nisin (12.5-25 ppm), nitrite (100-200 ppm) and organic acid salts (1.55-3.1 %) and the mixture of Chinese cinnamon and Cinnamon bark Essential Oils (EOs) (0.025-0.05 %). Based on the analysis, utilization of low (0.025 %) or high concentration (0.05 %) of EOs in combination with low concentration of nitrite (100 ppm), organic acid salts (1.55 %), and nisin (12.5 ppm) could reduce respectively 1.5 or 2.6 log CFU/g of L. monocytogenes in sausage at day 7 of storage as compared to the control. A predictive equation was created to predict the growth of L. monocytogenes in sausage. The sensory evaluation was then performed on selected optimized formulations in cooked meat (both pork and beef sausages) with a trained jury consisting of 35 individuals, demonstrated the selected antimicrobial formulations were organoleptically acceptable. The results revealed an important role of hurdle technology to control L. monocytogenes in meat product. PMID:27478218
Assi, Hisham; Cobbold, Richard S C
2016-04-01
Wave propagation in an infinite medium can be numerically simulated by surrounding a finite region by a perfectly matched layer (PML). When the medium is heterogeneous consisting of both solids and liquids, careful consideration is needed in specifying the properties of the PML especially because parts of it lie at the solid-fluid interface. While such a situation could arise in many important fields including marine seismology, where water is in contact with earth, and in biomedical ultrasound, where soft tissue is in contact with bone, no PML formulation exists to appropriately model such coupled problems. Here, a second-order time-domain PML formulation for fluid-solid heterogeneous media in two dimensions that satisfies the interface coupling boundary condition throughout the computational domain is presented. Numerical results are given to establish the applicability and accuracy of such a PML formulation in discrete settings without causing stability issues, spurious reflections, or any other problems. In particular, the effectiveness of the PML in absorbing all kinds of bulk waves, as well as surface and evanescent waves, is studied. PMID:27106301
Lindqvist, Annika; Fridén, Markus; Hammarlund-Udenaes, Margareta
2016-09-20
The use of nanocarriers is an intriguing solution to increase the brain delivery of novel therapeutics. The aim of this paper was to use pharmacokinetic analysis and simulations to identify key factors that determine the effective drug concentration-time profile at the target site in the brain. Model building and simulations were based on experimental data obtained from the administration of the opioid peptide DAMGO in glutathione tagged PEGylated liposomes to rats. Different pharmacokinetic models were investigated to explore the mechanisms of increased brain delivery. Concentration-time profiles for a set of formulations with varying compound and carrier characteristics were simulated. By controlling the release rate from the liposome, the time profile and the extent of brain delivery can be regulated. The modeling did not support a mechanism of the liposomes passing the brain endothelial cell membrane in an intact form through endocytosis or transcytosis. The most likely process was found to be fusion of the liposome with the endothelial luminal membrane. The simulations revealed that low permeable compounds, independent on efflux, will gain the most from a nanocarrier formulation. The present model based approach is useful to explore and predict possibilities and limitations of carrier-based systems to the brain. PMID:27393342
NASA Astrophysics Data System (ADS)
Miranda Fuentes, Johann; Kuznik, Frédéric; Johannes, Kévyn; Virgone, Joseph
2014-01-01
This article presents a new model to simulate melting with natural convection of a phase change material. For the phase change problem, the enthalpy formulation is used. Energy equation is solved by a finite difference method, whereas the fluid flow is solved by the multiple relaxation time (MRT) lattice Boltzmann method. The model is first verified and validated using the data from the literature. Then, the model is applied to a tall brick filled with a fatty acid eutectic mixture and the results are presented. The main results are (1) the spatial convergence rate is of second order, (2) the new model is validated against data from the literature and (3) the natural convection plays an important role in the melting process of the fatty acid mixture considered in our work.
NASA Astrophysics Data System (ADS)
Belferman, Mariana; Katsman, Regina; Agnon, Amotz
2015-04-01
The Levant has been repeatedly devastated by numerous earthquakes since prehistorical time, as recorded in historical documents, archaeological ruins, and sedimentary archives. In order to understand the role of the dynamics of the water bodies in triggering the deformations in the Levant basin, a new theoretical thermo-mechanical model is constructed and extended by including a fluid flow component. The latter is modeled on a basis of two-way poroelastic coupling with momentum equation. This coupling is essential to capture the fluid flow evolution induced by dynamic water loading and to resolve porosity changes. All the components of the model, namely elasticity, creep, plasticity, fluid flow, etc., have been extensively verified and presented. Results of the initial sensitivity analysis addressing the relative importance of each process in earthquakes triggering are discussed. The rich archives of pre-instrumental destructive earthquakes will set constraints for future modeling under the present formulation.
Sisini, Francesco; Zanca, Federica; Marshall, Nicholas W.; Taibi, Angelo; Cardarelli, Paolo; Bosmans, Hilde
2012-09-15
Purpose: Image quality indices based upon model observers are promising alternatives to laborious human readings of contrast-detail images. This is especially appealing in digital mammography as limiting values for contrast thresholds determine, according to some international protocols, the acceptability of these systems in the radiological practice. The objective of the present study was to compare the signal to noise ratios (SNR) obtained with two nonprewhitening matched filter model observer approaches, one in the spatial domain and the other in the frequency domain, and with both of them worked out for disks as present in the CDMAM phantom. Methods: The analysis was performed using images acquired with the Siemens Novation and Inspiration digital mammography systems. The spatial domain formulation uses a series of high dose CDMAM images as the signal and a routine exposure of two flood images to calculate the covariance matrix. The frequency domain approach uses the mathematical description of a disk and modulation transfer function (MTF) and noise power spectrum (NPS) calculated from images. Results: For both systems most of the SNR values calculated in the frequency domain were in very good agreement with the SNR values calculated in the spatial domain. Both the formulations in the frequency domain and in the spatial domain show a linear relationship between SNR and the diameter of the CDMAM discs. Conclusions: The results suggest that both formulations of the model observer lead to very similar figures of merit. This is a step forward in the adoption of figures of merit based on NPS and MTF for the acceptance testing of mammography systems.
NASA Astrophysics Data System (ADS)
Morgenstern, O.; Giorgetta, M. A.; Shibata, K.; Eyring, V.; Waugh, D. W.; Shepherd, T. G.; Akiyoshi, H.; Austin, J.; Baumgaertner, A. J. G.; Bekki, S.; Braesicke, P.; Brühl, C.; Chipperfield, M. P.; Cugnet, D.; Dameris, M.; Dhomse, S.; Frith, S. M.; Garny, H.; Gettelman, A.; Hardiman, S. C.; Hegglin, M. I.; JöCkel, P.; Kinnison, D. E.; Lamarque, J.-F.; Mancini, E.; Manzini, E.; Marchand, M.; Michou, M.; Nakamura, T.; Nielsen, J. E.; Olivié, D.; Pitari, G.; Plummer, D. A.; Rozanov, E.; Scinocca, J. F.; Smale, D.; TeyssèDre, H.; Toohey, M.; Tian, W.; Yamashita, Y.
2010-01-01
The goal of the Chemistry-Climate Model Validation (CCMVal) activity is to improve understanding of chemistry-climate models (CCMs) through process-oriented evaluation and to provide reliable projections of stratospheric ozone and its impact on climate. An appreciation of the details of model formulations is essential for understanding how models respond to the changing external forcings of greenhouse gases and ozone-depleting substances, and hence for understanding the ozone and climate forecasts produced by the models participating in this activity. Here we introduce and review the models used for the second round (CCMVal-2) of this intercomparison, regarding the implementation of chemical, transport, radiative, and dynamical processes in these models. In particular, we review the advantages and problems associated with approaches used to model processes of relevance to stratospheric dynamics and chemistry. Furthermore, we state the definitions of the reference simulations performed, and describe the forcing data used in these simulations. We identify some developments in chemistry-climate modeling that make models more physically based or more comprehensive, including the introduction of an interactive ocean, online photolysis, troposphere-stratosphere chemistry, and non-orographic gravity-wave deposition as linked to tropospheric convection. The relatively new developments indicate that stratospheric CCM modeling is becoming more consistent with our physically based understanding of the atmosphere.
NASA Astrophysics Data System (ADS)
Ramadan, Omar
2015-09-01
In this paper, systematic wave-equation finite difference time domain (WE-FDTD) formulations are presented for modeling electromagnetic wave-propagation in linear and nonlinear dispersive materials. In the proposed formulations, the complex conjugate pole residue (CCPR) pairs model is adopted in deriving a unified dispersive WE-FDTD algorithm that allows modeling different dispersive materials, such as Debye, Drude and Lorentz, in the same manner with the minimal additional auxiliary variables. Moreover, the proposed formulations are incorporated with the wave-equation perfectly matched layer (WE-PML) to construct a material independent mesh truncating technique that can be used for modeling general frequency-dependent open region problems. Several numerical examples involving linear and nonlinear dispersive materials are included to show the validity of the proposed formulations.
NASA Technical Reports Server (NTRS)
Song, Y. T.
1998-01-01
A Jacobian formulation of the pressure gradient force for use in models with topography following coordinates is proposed. It can be used in conjunction with any vertical coordinate system and is easily implemented.
NASA Astrophysics Data System (ADS)
Liu, Yang; Fang, Zhi-gang; You, Ben-Gang; Ding, Xin-yuan; Zhang, Xue-nong
The modelling pharmacokinetic profile of freeze-dried cyclosporine A-Eudragit S100 nanoparticles (CyA-S100-NP) was studied with a random two-way crossover study in dogs. The drug blood concentration was determined by internal standard HPLC method after oral administration of CyA-S100-NP and Neoral. Pharmacokinetics modellng parameters were calculated by 3P97modelling program. The concentration-time data were fitted as a two-compartment open model. The AUC of CyA-S100-NP was higher than that of Neoral (P<0.05), while the CL significantly decreased (P<0.05). The relative bioavailability of CyA-S100-NP were 135.9% compared with Neoral. The bioavailability of CyA was significantly improved. CyA-S100-NP was a potential drug for developing a new CyA nanoparticles solid formulation.
Kessinger, Glen Frank; Nelson, Lee Orville; Grandy, Jon Drue; Zuck, Larry Douglas; Kong, Peter Chuen Sun; Anderson, Gail
1999-08-01
The purpose of LDRD #2349, Characterize and Model Final Waste Formulations and Offgas Solids from Thermal Treatment Processes, was to develop a set of tools that would allow the user to, based on the chemical composition of a waste stream to be immobilized, predict the durability (leach behavior) of the final waste form and the phase assemblages present in the final waste form. The objectives of the project were: • investigation, testing and selection of thermochemical code • development of auxiliary thermochemical database • synthesis of materials for leach testing • collection of leach data • using leach data for leach model development • thermochemical modeling The progress toward completion of these objectives and a discussion of work that needs to be completed to arrive at a logical finishing point for this project will be presented.
NASA Astrophysics Data System (ADS)
Cassiani, Massimo; Stohl, Andreas; Brioude, Jerome
2015-03-01
A correction for the vertical gradient of air density has been incorporated into a skewed probability density function formulation for turbulence in the convective boundary layer. The related drift term for Lagrangian stochastic dispersion modelling has been derived based on the well-mixed condition. Furthermore, the formulation has been extended to include unsteady turbulence statistics and the related additional component of the drift term obtained. These formulations are an extension of the drift formulation reported by Luhar et al. (Atmos Environ 30:1407-1418, 1996) following the well-mixed condition proposed by Thomson (J Fluid Mech 180:529-556, 1987). Comprehensive tests were carried out to validate the formulations including consistency between forward and backward simulations and preservation of a well-mixed state with unsteady conditions. The stationary state CBL drift term with density correction was incorporated into the FLEXPART and FLEXPART-WRF Lagrangian models, and included the use of an ad hoc transition function that modulates the third moment of the vertical velocity based on stability parameters. Due to the current implementation of the FLEXPART models, only a steady-state horizontally homogeneous drift term could be included. To avoid numerical instability, in the presence of non-stationary and horizontally inhomogeneous conditions, a re-initialization procedure for particle velocity was used. The criteria for re-initialization and resulting errors were assessed for the case of non-stationary conditions by comparing a reference numerical solution in simplified unsteady conditions, obtained using the non-stationary drift term, and a solution based on the steady drift with re-initialization. Two examples of "real-world" numerical simulations were performed under different convective conditions to demonstrate the effect of the vertical gradient in density on the particle dispersion in the CBL.
Evaluation of a photosyntheses-based canopy resistance formulation in the Noah Land-surface model
Technology Transfer Automated Retrieval System (TEKTRAN)
Accurately representing complex land-surface processes balancing complexity and realism remains one challenge that the weather modelling community is facing nowadays. In this study, a photosynthesis-based Gas-exchange Evapotranspiration Model (GEM) is integrated into the Noah land-surface model repl...
The application of remote sensing to the development and formulation of hydrologic planning models
NASA Technical Reports Server (NTRS)
Fowler, T. R.; Castruccio, P. A.; Loats, H. L., Jr.
1977-01-01
The development of a remote sensing model and its efficiency in determining parameters of hydrologic models are reviewed. Procedures for extracting hydrologic data from LANDSAT imagery, and the visual analysis of composite imagery are presented. A hydrologic planning model is developed and applied to determine seasonal variations in watershed conditions. The transfer of this technology to a user community and contract arrangements are discussed.
The application of remote sensing to the development and formulation of hydrologic planning models
NASA Technical Reports Server (NTRS)
Castruccio, P. A.; Loats, H. L., Jr.; Fowler, T. R.
1976-01-01
A hydrologic planning model is developed based on remotely sensed inputs. Data from LANDSAT 1 are used to supply the model's quantitative parameters and coefficients. The use of LANDSAT data as information input to all categories of hydrologic models requiring quantitative surface parameters for their effects functioning is also investigated.
Model formulation of non-equilibrium gas radiation for hypersonic flight vehicles
NASA Technical Reports Server (NTRS)
Chang, Ing
1989-01-01
Several radiation models for low density nonequilibrium hypersonic flow are studied. It is proposed that these models should be tested by the 3-D VRFL code developed at NASA/JSC. A modified and optimized radiation model may be obtained from the testing. Then, the current VRFL code could be expanded to solve hypersonic flow problems with nonequilibrium thermal radiation.
Rossi, Federico; Nicolini, Andrea
2003-05-01
No suitable handy tool is available to predict train-induced vibration on environmental impact assessment. A simple prediction model is proposed which has been calibrated for high speed trains. The model input data are train characteristics, train speed and track properties; model output data are soil time-averaged velocity and velocity level. Model results have been compared with numerous vibration data retrieved from measurement campaigns led along the most important high-speed European rail tracks. Model performances have been tested by comparing measured and predicted vibration values.
NASA Astrophysics Data System (ADS)
Chaynikov, S.; Porta, G.; Riva, M.; Guadagnini, A.
2012-04-01
We focus on a theoretical analysis of nonreactive solute transport in porous media through the volume averaging technique. Darcy-scale transport models based on continuum formulations typically include large scale dispersive processes which are embedded in a pore-scale advection diffusion equation through a Fickian analogy. This formulation has been extensively questioned in the literature due to its inability to depict observed solute breakthrough curves in diverse settings, ranging from the laboratory to the field scales. The heterogeneity of the pore-scale velocity field is one of the key sources of uncertainties giving rise to anomalous (non-Fickian) dispersion in macro-scale porous systems. Some of the models which are employed to interpret observed non-Fickian solute behavior make use of a continuum formulation of the porous system which assumes a two-region description and includes a bimodal velocity distribution. A first class of these models comprises the so-called ''mobile-immobile'' conceptualization, where convective and dispersive transport mechanisms are considered to dominate within a high velocity region (mobile zone), while convective effects are neglected in a low velocity region (immobile zone). The mass exchange between these two regions is assumed to be controlled by a diffusive process and is macroscopically described by a first-order kinetic. An extension of these ideas is the two equation ''mobile-mobile'' model, where both transport mechanisms are taken into account in each region and a first-order mass exchange between regions is employed. Here, we provide an analytical derivation of two region "mobile-mobile" meso-scale models through a rigorous upscaling of the pore-scale advection diffusion equation. Among the available upscaling methodologies, we employ the Volume Averaging technique. In this approach, the heterogeneous porous medium is supposed to be pseudo-periodic, and can be represented through a (spatially) periodic unit cell
Kremer, Lauren E; McLeod, Andrew I; Aitken, Jade B; Levina, Aviva; Lay, Peter A
2015-06-01
Uncontrolled reactions in biological media are a main obstacle for clinical translation of V-based anti-diabetic or anti-cancer pro-drugs. We investigated the use of controlled-release pharmaceutical formulations to ameliorate this issue with a series of V(V) and (IV) complexes of anionic polysaccharides. Carboxymethyl cellulose, xanthan gum, or alginic acid formulations were prepared by the reactions of [VO4](3-) with one or two molar equivalents of biological reductants, L-ascorbic acid (AA) or L-cysteine (Cys), in the presence of excess polysaccharide at pH~7 or pH~4. XANES studies with the use of a previously developed library of model V(V), V(IV) and V(III) complexes showed that reactions in the presence of AA led mostly to the mixtures of five- and six-coordinate V(IV) species, while the reactions in the presence of Cys led predominantly to the mixtures of five- and six-coordinate V(V) species. The XANES spectra of some of these samples closely matched those reported previously for [VO4](3-) biotransformation products in isolated blood plasma, red blood cells, or cultured adipocytes, which supports the hypothesis that modified polysaccharides are major binders of V(V) and V(IV) in biological systems. Studies by EPR spectroscopy suggested predominant V(IV)-carboxylato binding in complexes with polysaccharides. One of the isolated products (a V(IV)-alginato complex) showed selective release of low-molecular-mass V species at pH~8, but not at pH~2, which makes it a promising lead for the development of V-containing formulations for oral administration that are stable in the stomach, but release the active ingredient in the intestines. PMID:25958254
NASA Astrophysics Data System (ADS)
Kulshreshtha, Usha; Kulshreshtha, Daya Shankar; Vary, James P.
2016-01-01
Recently (in a series of papers) we have studied the vector Schwinger model with a photon mass term describing one-space one-time dimensional electrodynamics with mass-less fermions in the so-called standard regularization. In the present work, we study this model in the Faddeevian regularization (FR). This theory in the FR is seen to be gauge-non-invariant (GNI). We study the Hamiltonian and path integral quantization of this GNI theory. We then construct a gauge-invariant (GI) theory corresponding to this GNI theory using the Stueckelberg mechanism and recover the physical content of the original GNI theory from the newly constructed GI theory under some special gauge-choice. Further, we study the Hamiltonian, path integral and Becchi-Rouet-Stora and Tyutin formulations of the newly constructed GI theory under appropriate gauge-fixing conditions.
NASA Astrophysics Data System (ADS)
Teoh, Lay Eng; Khoo, Hooi Ling
2013-09-01
This study deals with two major aspects of airlines, i.e. supply and demand management. The aspect of supply focuses on the mathematical formulation of an optimal fleet management model to maximize operational profit of the airlines while the aspect of demand focuses on the incorporation of mode choice modeling as parts of the developed model. The proposed methodology is outlined in two-stage, i.e. Fuzzy Analytic Hierarchy Process is first adopted to capture mode choice modeling in order to quantify the probability of probable phenomena (for aircraft acquisition/leasing decision). Then, an optimization model is developed as a probabilistic dynamic programming model to determine the optimal number and types of aircraft to be acquired and/or leased in order to meet stochastic demand during the planning horizon. The findings of an illustrative case study show that the proposed methodology is viable. The results demonstrate that the incorporation of mode choice modeling could affect the operational profit and fleet management decision of the airlines at varying degrees.
On the formulation of the dynamic mixed subgrid-scale model
NASA Astrophysics Data System (ADS)
Vreman, Bert; Geurts, Bernard; Kuerten, Hans
1994-12-01
The dynamic mixed subgrid-scale model of Zang et al. [Phys. Fluids A 5, 3186 (1993)] (DMM1) is modified with respect to the incorporation of the similarity model in order to remove a mathematical inconsistency. Compared to DMM1, the magnitude of the dynamic model coefficient of the modified model (DMM2) is increased considerably, while it is still significantly smaller than as occurs in the dynamic subgrid-scale eddy-viscosity model of Germano [J. Fluid Mech. 238, 325 (1992)] (DSM). Large eddy simulations (LES) for the weakly compressible mixing layer are conducted using these three models and results are compared with direct numerical simulation (DNS) data. LES based on DMM1 gives a significant improvement over LES using DSM, while even better agreement is achieved with DMM2.
Plan, formulate, and discuss a NASTRAN finite element model of the AH-64A helicopter airframe
NASA Technical Reports Server (NTRS)
Christ, Richard A.; Ferg, Douglas A.; Kilroy, Kevin A.; Toossi, Mostafa; Weisenburger, Richard K.
1990-01-01
A discussion of modeling plan objectives, followed by a description of the AH-64A aircraft including all general features, major components, and primary and structure definitions are presented. Following the aircraft description, a discussion of the modeling guidelines and model checkout procedure are provided. The NASTRAN finite element analysis is set up to be suitable to predict both static internal loads and vibrations. Finally, the results, schedule, and planned versus actual manhours for this work are presented.
Application of remote sensing to hydrology. [for the formulation of watershed behavior models
NASA Technical Reports Server (NTRS)
Ambaruch, R.; Simmons, J. W.
1973-01-01
Streamflow forecasting and hydrologic modelling are considered in a feasibility assessment of using the data produced by remote observation from space and/or aircraft to reduce the time and expense normally involved in achieving the ability to predict the hydrological behavior of an ungaged watershed. Existing watershed models are described, and both stochastic and parametric techniques are discussed towards the selection of a suitable simulation model. Technical progress and applications are reported and recommendations are made for additional research.
A one-dimensional interactive soil-atmosphere model for testing formulations of surface hydrology
NASA Technical Reports Server (NTRS)
Koster, Randal D.; Eagleson, Peter S.
1990-01-01
A model representing a soil-atmosphere column in a GCM is developed for off-line testing of GCM soil hydrology parameterizations. Repeating three representative GCM sensitivity experiments with this one-dimensional model demonstrates that, to first order, the model reproduces a GCM's sensitivity to imposed changes in parameterization and therefore captures the essential physics of the GCM. The experiments also show that by allowing feedback between the soil and atmosphere, the model improves on off-line tests that rely on prescribed precipitation, radiation, and other surface forcing.
Painter, Scott L.; Coon, Ethan T.; Atchley, Adam L.; Berndt, Markus; Garimella, Rao; Moulton, J. David; Svyatskiy, Daniil; Wilson, Cathy J.
2016-08-11
The need to understand potential climate impacts and feedbacks in Arctic regions has prompted recent interest in modeling of permafrost dynamics in a warming climate. A new fine-scale integrated surface/subsurface thermal hydrology modeling capability is described and demonstrated in proof-of-concept simulations. The new modeling capability combines a surface energy balance model with recently developed three-dimensional subsurface thermal hydrology models and new models for nonisothermal surface water flows and snow distribution in the microtopography. Surface water flows are modeled using the diffusion wave equation extended to include energy transport and phase change of ponded water. Variation of snow depth in themore » microtopography, physically the result of wind scour, is also modeled heuristically with a diffusion wave equation. The multiple surface and subsurface processes are implemented by leveraging highly parallel community software. Fully integrated thermal hydrology simulations on the tilted open book catchment, an important test case for integrated surface/subsurface flow modeling, are presented. Fine-scale 100-year projections of the integrated permafrost thermal hydrological system on an ice wedge polygon at Barrow Alaska in a warming climate are also presented. Finally, these simulations demonstrate the feasibility of microtopography-resolving, process-rich simulations as a tool to help understand possible future evolution of the carbon-rich Arctic tundra in a warming climate.« less
Korang-Yeboah, Maxwell; Rahman, Ziyaur; Shah, Dhaval A; Khan, Mansoor A
2016-01-01
Variations in the solid state form of a pharmaceutical solid have profound impact on the product quality and clinical performance. Quantitative models that allow rapid and accurate determination of polymorphic changes in pharmaceutical products are essential in ensuring product quality throughout its lifecycle. This study reports the development and validation of chemometric models of Raman and near infrared spectroscopy (NIR) for quantifying the extent of pseudopolymorphic transitions of theophylline in extended release formulations. The chemometric models were developed using sample matrices consisting of the commonly used excipients and at the ratios in commercially available products. A combination of scatter removal (multiplicative signal correction and standard normal variate) and derivatization (Savitzky-Golay second derivative) algorithm were used for data pretreatment. Partial least squares and principal component regression models were developed and their performance assessed. Diagnostic statistics such as the root mean square error, correlation coefficient, bias and Q(2) were used as parameters to test the model fit and performance. The models developed had a good fit and performance as shown by the values of the diagnostic statistics. The model diagnostic statistics were similar for MSC-SG and SNV-SG treated spectra. Similarly, PLSR and PCR models had comparable performance. Raman chemometric models were slightly better than their corresponding NIR model. The Raman and NIR chemometric models developed had good accuracy and precision as demonstrated by closeness of the predicted values for the independent observations to the actual TMO content hence the developed models can serve as useful tools in quantifying and controlling solid state transitions in extended release theophylline products. PMID:26852844
Täuber, Anja; Müller-Goymann, Christel C
2014-07-01
Onychomycosis is a fungal infection mostly induced by dermatophytes such as Trichophyton rubrum. Due to slow nail growth, the treatment takes 3-9 months depending on the nail size and infected area. Hence, high efficacy of the active ingredient without systemic side effects is of major interest. To test the efficacy of an antifungal formulation, an appropriate in vitro model reflecting the in vivo situation as close as possible is required. In this study, a variety of antifungal formulations, i.e., commercial ones (Ciclopoli and Lamisil cream), those used in compounding pharmacies (Pentravan) as well as poloxamer 407-based systems, have been evaluated in an infected nail plate model. The active pharmaceutical ingredients (APIs) were ciclopirox olamine and terbinafine hydrochloride. The poloxamer 407-based formulations consisted of poloxamer 407, double distilled water, propylene glycol, isopropyl alcohol, medium chain triglycerides and either 1% ciclopirox olamine or 1% terbinafine hydrochloride as API, respectively. Former studies have shown high permeation rates of terbinafine hydrochloride from similar poloxamer 407-based formulations with dimethyl isosorbide instead of propylene glycol. The present contribution shows superior inhibition of T. rubrum growth from poloxamer 407-based formulations in comparison to the commercial Lamisil cream. Moreover, poloxamer 407-based formulations were equally effective as the nail lacquer Ciclopoli even though the poloxamer formulations contained only 1% of the drug instead of 8% in the marketed lacquer. Poloxamer 407-based systems containing ciclopirox olamine proved to be about as effective as similar terbinafine hydrochloride systems. PMID:24490976
REGIONAL SCALE (1000 KM) MODEL OF PHOTOCHEMICAL AIR POLLUTION. PART 1. THEORETICAL FORMULATION
A theoretical framework for a multi-day 1000 km scale simulation model of photochemical oxidant is developed. It is structured in a highly modular form so that eventually the model can be applied through straightforward modifications to simulations of particulates, visibility and...
The application of remote sensing to the development and formulation of hydrologic planning models
NASA Technical Reports Server (NTRS)
Castruccio, P. A.; Loats, H. L., Jr.; Fowler, T. R.; Frech, S. L.
1975-01-01
Regional hydrologic planning models built upon remote sensing capabilities and suited for ungaged watersheds are developed. The effectiveness of such models is determined along with which parameters impact most the minimization of errors associated with the prediction of peak flow events (floods). Emphasis is placed on peak flood prediction because of its significance to users for the purpose of planning, sizing, and designing waterworks.
A self-adjusting flow dependent formulation for the classical Smagorinsky model coefficient
NASA Astrophysics Data System (ADS)
Ghorbaniasl, G.; Agnihotri, V.; Lacor, C.
2013-05-01
In this paper, we propose an efficient formula for estimating the model coefficient of a Smagorinsky model based subgrid scale eddy viscosity. The method allows vanishing eddy viscosity through a vanishing model coefficient in regions where the eddy viscosity should be zero. The advantage of this method is that the coefficient of the subgrid scale model is a function of the flow solution, including the translational and the rotational velocity field contributions. Furthermore, the value of model coefficient is optimized without using the dynamic procedure thereby saving significantly on computational cost. In addition, the method guarantees the model coefficient to be always positive with low fluctuation in space and time. For validation purposes, three test cases are chosen: (i) a fully developed channel flow at {mathopRenolimits} _tau = 180, 395, (ii) a fully developed flow through a rectangular duct of square cross section at {mathopRenolimits} _tau = 300, and (iii) a smooth subcritical flow past a stationary circular cylinder, at a Reynolds number of {mathopRenolimits} = 3900, where the wake is fully turbulent but the cylinder boundary layers remain laminar. A main outcome is the good behavior of the proposed model as compared to reference data. We have also applied the proposed method to a CT-based simplified human upper airway model, where the flow is transient.
Formulation and calibration of a stochastic model form error representation for RANS
NASA Astrophysics Data System (ADS)
Oliver, Todd; Reuter, Bryan; Moser, Robert
2014-11-01
It is well-known that RANS turbulence models fail to accurately represent the effects of turbulence on the mean flow for many important flows. We consider probabilistic representations of this model inadequacy for wall-bounded flows. The particular probabilistic representations considered here take the form of stochastic differential equations that are loosely based on the Reynolds stress transport equations, but include random forcing to represent uncertainty due to the closure problem. This model is disretized using finite elements and a priori uncertainty quantification studies are conducted using Monte Carlo sampling. The results demonstrate that the resulting uncertainties in the mean velocity scale as desired with Reynolds number. In addition to the random forcing, the model contains a number of uncertain parameters. We demonstrate that these can be calibrated using available DNS data. The model is further tested via comparison against additional DNS data outside of the orignal calibration set.
NASA Astrophysics Data System (ADS)
Kosztołowicz, Tadeusz; Lewandowska, Katarzyna
2012-06-01
We consider here two different models describing subdiffusion. One of them is derived from Continuous Time Random Walk formalism and utilizes a subdiffusion equation with a fractional time derivative. The second model is based on Sharma-Mittal nonadditive entropy formalism where the subdiffusive process is described by a nonlinear equation with ordinary derivatives. Using these two models we describe the process of a substance released from a thick membrane and we find functions which determine the time evolution of the amount of substance remaining inside this membrane. We then find `the agreement conditions' under which these two models provide the same relation defining subdiffusion and give the same function characterizing the process of the released substance. These agreement conditions enable us to determine the relation between the parameters occuring in both models.
Lusiana; Reichl, Stephan; Müller-Goymann, Christel C
2013-08-01
A novel model of infected nail plate for testing the efficacy of topical antifungal formulations has been developed. This model utilized keratin film made of human hair keratin as a nail plate model. Subsequent to infection by Trichophyton rubrum, the common causative agent of onychomycosis, keratin films as infected nail plate models were treated with selected topical formulations, that is cream, gel, and nail lacquer. Bovine hoof was compared to keratin film. In contrast to the common antifungal susceptibility test, the antifungal drugs tested were applied as ready-to-use formulations because the vehicle may modify and control the drug action both in vitro and in vivo. Extrapolating the potency of an antifungal drug from an in vitro susceptibility test only would not be representative of the in vivo situation since these drugs are applied as ready-to-use formulations, for example as a nail lacquer. Although terbinafine has been acknowledged to be the most effective antifungal agent against T. rubrum, its antifungal efficacy was improved by its incorporation into an optimal formulation. Different gels proved superior to cream. Therefore, this study is able to discriminate between efficacies of different topical antifungal formulations based on their activities against T. rubrum. PMID:23419812
Jones, Sarah; Asokanathan, Catpagavalli; Kmiec, Dorota; Irvine, June; Fleck, Roland; Xing, Dorothy; Moore, Barry; Parton, Roger; Coote, John
2014-01-01
Protein-coated microcrystals (PCMCs) were investigated as potential vaccine formulations for a range of model antigens. Presentation of antigens as PCMCs increased the antigen-specific IgG responses for all antigens tested, compared to soluble antigens. When compared to conventional aluminium-adjuvanted formulations, PCMCs modified with calcium phosphate (CaP) showed enhanced antigen-specific IgG responses and a decreased antigen-specific IgG1:IgG2a ratio, indicating the induction of a more balanced Th1/Th2 response. The rate of antigen release from CaP PCMCs, in vitro, decreased strongly with increasing CaP loading but their immunogenicity in vivo was not significantly different, suggesting the adjuvanticity was not due to a depot effect. Notably, it was found that CaP modification enhanced the phagocytosis of fluorescent antigen-PCMC particles by J774.2 murine monocyte/macrophage cells compared to soluble antigen or soluble PCMCs. Thus, CaP PCMCs may provide an alternative to conventional aluminium-based acellular vaccines to provide a more balanced Th1/Th2 immune response. PMID:24120484
Classical and Quantum Formulations of S1xS2 and S3 Gowdy Models Coupled with Matter
NASA Astrophysics Data System (ADS)
Gómez Vergel, Daniel
2009-10-01
We explore the features of gravity in its quantum regime in a mathematically rigorous way by carrying out the classical and quantum formulations of some two-Killing symmetry reductions of general relativity which admit an exact Fock/Schrödinger quantization. Concretely, we analyze in depth the linearly polarized 3-handle (S1xS2) and 3-sphere (S3) Gowdy cosmological models coupled to massless scalar fields. Within the classical formulation, this study requires a careful application of modern differential geometry techniques and the Dirac-Bergmann theory of constrained systems. Regarding the quantization process, we analyze the construction of both Fock and Schrödinger representations, the unitarity of the time evolution, and the existence of semiclassical states for these systems by making use of the algebraic formalism of quantum theory and the theory of unitary implementation of symplectic transformations. Several appendices give additional information on the results attained in the main body of the thesis, going deeply into the relevant mathematical aspects of the text.
Jones, Sarah; Asokanathan, Catpagavalli; Kmiec, Dorota; Irvine, June; Fleck, Roland; Xing, Dorothy; Moore, Barry; Parton, Roger; Coote, John
2014-07-16
Protein-coated microcrystals (PCMCs) were investigated as potential vaccine formulations for a range of model antigens. Presentation of antigens as PCMCs increased the antigen-specific IgG responses for all antigens tested, compared to soluble antigens. When compared to conventional aluminium-adjuvanted formulations, PCMCs modified with calcium phosphate (CaP) showed enhanced antigen-specific IgG responses and a decreased antigen-specific IgG1:IgG2a ratio, indicating the induction of a more balanced Th1/Th2 response. The rate of antigen release from CaP PCMCs, in vitro, decreased strongly with increasing CaP loading but their immunogenicity in vivo was not significantly different, suggesting the adjuvanticity was not due to a depot effect. Notably, it was found that CaP modification enhanced the phagocytosis of fluorescent antigen-PCMC particles by J774.2 murine monocyte/macrophage cells compared to soluble antigen or soluble PCMCs. Thus, CaP PCMCs may provide an alternative to conventional aluminium-based acellular vaccines to provide a more balanced Th1/Th2 immune response. PMID:24120484
NASA Astrophysics Data System (ADS)
Tonge, Andrew L.; Ramesh, K. T.
2016-01-01
Within this two part series we develop a new material model for ceramic protection materials to provide an interface between microstructural parameters and bulk continuum behavior to provide guidance for materials design activities. Part I of this series focuses on the model formulation that captures the strength variability and strain rate sensitivity of brittle materials and presents a statistical approach to assigning the local flaw distribution within a specimen. The material model incorporates a Mie-Grüneisen equation of state, micromechanics based damage growth, granular flow and dilatation of the highly damaged material, and pore compaction for the porosity introduced by granular flow. To provide initial qualitative validation and illustrate the usefulness of the model, we use the model to investigate Edge on Impact experiments (Strassburger, 2004) on Aluminum Oxynitride (AlON), and discuss the interactions of multiple mechanisms during such an impact event. Part II of this series is focused on additional qualitative validation and using the model to suggest material design directions for boron carbide.
Mousavi, Sayyed R; Khodadadi, Ilnaz; Falsafain, Hossein; Nadimi, Reza; Ghadiri, Nasser
2014-06-01
Human haplotypes include essential information about SNPs, which in turn provide valuable information for such studies as finding relationships between some diseases and their potential genetic causes, e.g., for Genome Wide Association Studies. Due to expensiveness of directly determining haplotypes and recent progress in high throughput sequencing, there has been an increasing motivation for haplotype assembly, which is the problem of finding a pair of haplotypes from a set of aligned fragments. Although the problem has been extensively studied and a number of algorithms have already been proposed for the problem, more accurate methods are still beneficial because of high importance of the haplotypes information. In this paper, first, we develop a probabilistic model, that incorporates the Minor Allele Frequency (MAF) of SNP sites, which is missed in the existing maximum likelihood models. Then, we show that the probabilistic model will reduce to the Minimum Error Correction (MEC) model when the information of MAF is omitted and some approximations are made. This result provides a novel theoretical support for the MEC, despite some criticisms against it in the recent literature. Next, under the same approximations, we simplify the model to an extension of the MEC in which the information of MAF is used. Finally, we extend the haplotype assembly algorithm HapSAT by developing a weighted Max-SAT formulation for the simplified model, which is evaluated empirically with positive results. PMID:24491253
NASA Astrophysics Data System (ADS)
Knani, S.; Aouaini, F.; Bahloul, N.; Khalfaoui, M.; Hachicha, M. A.; Ben Lamine, A.; Kechaou, N.
2014-04-01
Analytical expression for modeling water adsorption isotherms of food or agricultural products is developed using the statistical mechanics formalism. The model developed in this paper is further used to fit and interpret the isotherms of four varieties of Tunisian olive leaves called “Chemlali, Chemchali, Chetoui and Zarrazi”. The parameters involved in the model such as the number of adsorbed water molecules per site, n, the receptor sites density, NM, and the energetic parameters, a1 and a2, were determined by fitting the experimental adsorption isotherms at temperatures ranging from 303 to 323 K. We interpret the results of fitting. After that, the model is further applied to calculate thermodynamic functions which govern the adsorption mechanism such as entropy, the free enthalpy of Gibbs and the internal energy.
The Community Multiscale Air Quality (CMAQ) modeling system has recently been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury in three distinct forms; elemental mercury gas, reactive gaseous mercury, and particulate mercury. Emis...
NASA Astrophysics Data System (ADS)
Lemarié, F.; Debreu, L.; Madec, G.; Demange, J.; Molines, J. M.; Honnorat, M.
2015-08-01
Except for vertical diffusion (and possibly the external mode and bottom drag), oceanic models usually rely on explicit time-stepping algorithms subject to Courant-Friedrichs-Lewy (CFL) stability criteria. Implicit methods could be unconditionally stable, but an algebraic system must be solved at each time step and other considerations such as accuracy and efficiency are less straightforward to achieve. Depending on the target application, the process limiting the maximum allowed time-step is generally different. In this paper, we introduce offline diagnostics to predict stability limits associated with internal gravity waves, advection, diffusion, and rotation. This suite of diagnostics is applied to a set of global, regional and coastal numerical simulations with several horizontal/vertical resolutions and different numerical models. We show that, for resolutions finer that 1/2°, models with an Eulerian vertical coordinate are generally constrained by vertical advection in a few hot spots and that numerics must be extremely robust to changes in Courant number. Based on those results, we review the stability and accuracy of existing numerical kernels in vogue in primitive equations oceanic models with a focus on advective processes and the dynamics of internal waves. We emphasize the additional value of studying the numerical kernel of oceanic models in the light of coupled space-time approaches instead of studying the time schemes independently from spatial discretizations. From this study, we suggest some guidelines for the development of temporal schemes in future generation multi-purpose oceanic models.
NASA Astrophysics Data System (ADS)
Charles, T. K.; Paganin, D. M.; Dowd, R. T.
2016-08-01
Intrinsic emittance is often the limiting factor for brightness in fourth generation light sources and as such, a good understanding of the factors affecting intrinsic emittance is essential in order to be able to decrease it. Here we present a parameterization model describing the proportional increase in emittance induced by cathode surface roughness. One major benefit behind the parameterization approach presented here is that it takes the complexity of a Monte Carlo model and reduces the results to a straight-forward empirical model. The resulting models describe the proportional increase in transverse momentum introduced by surface roughness, and are applicable to various metal types, photon wavelengths, applied electric fields, and cathode surface terrains. The analysis includes the increase in emittance due to changes in the electric field induced by roughness as well as the increase in transverse momentum resultant from the spatially varying surface normal. We also compare the results of the Parameterization Model to an Analytical Model which employs various approximations to produce a more compact expression with the cost of a reduction in accuracy.
Reversible Parallel Discrete Event Formulation of a TLM-based Radio Signal Propagation Model
Seal, Sudip K; Perumalla, Kalyan S
2011-01-01
Radio signal strength estimation is essential in many applications, including the design of military radio communications and industrial wireless installations. For scenarios with large or richly- featured geographical volumes, parallel processing is required to meet the memory and computa- tion time demands. Here, we present a scalable and efficient parallel execution of the sequential model for radio signal propagation recently developed by Nutaro et al. Starting with that model, we (a) provide a vector-based reformulation that has significantly lower computational overhead for event handling, (b) develop a parallel decomposition approach that is amenable to reversibility with minimal computational overheads, (c) present a framework for transparently mapping the conservative time-stepped model into an optimistic parallel discrete event execution, (d) present a new reversible method, along with its analysis and implementation, for inverting the vector-based event model to be executed in an optimistic parallel style of execution, and (e) present performance results from implementation on Cray XT platforms. We demonstrate scalability, with the largest runs tested on up to 127,500 cores of a Cray XT5, enabling simulation of larger scenarios and with faster execution than reported before on the radio propagation model. This also represents the first successful demonstration of the ability to efficiently map a conservative time-stepped model to an optimistic discrete-event execution.
NASA Technical Reports Server (NTRS)
Wind, Galina; DaSilva, Arlindo M.; Norris, Peter M.; Platnick, Steven E.
2013-01-01
In this paper we describe a general procedure for calculating equivalent sensor radiances from variables output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint the algorithm takes explicit account of the model subgrid variability, in particular its description of the probably density function of total water (vapor and cloud condensate.) The equivalent sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies. We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products.) We focus on clouds and cloud/aerosol interactions, because they are very important to model development and improvement.
NASA Astrophysics Data System (ADS)
Zhang, Xiang; Vu-Quoc, Loc
2007-07-01
We present in this paper the displacement-driven version of a tangential force-displacement (TFD) model that accounts for both elastic and plastic deformations together with interfacial friction occurring in collisions of spherical particles. This elasto-plastic frictional TFD model, with its force-driven version presented in [L. Vu-Quoc, L. Lesburg, X. Zhang. An accurate tangential force-displacement model for granular-flow simulations: contacting spheres with plastic deformation, force-driven formulation, Journal of Computational Physics 196(1) (2004) 298-326], is consistent with the elasto-plastic frictional normal force-displacement (NFD) model presented in [L. Vu-Quoc, X. Zhang. An elasto-plastic contact force-displacement model in the normal direction: displacement-driven version, Proceedings of the Royal Society of London, Series A 455 (1991) 4013-4044]. Both the NFD model and the present TFD model are based on the concept of additive decomposition of the radius of contact area into an elastic part and a plastic part. The effect of permanent indentation after impact is represented by a correction to the radius of curvature. The effect of material softening due to plastic flow is represented by a correction to the elastic moduli. The proposed TFD model is accurate, and is validated against nonlinear finite element analyses involving plastic flows in both the loading and unloading conditions. The proposed consistent displacement-driven, elasto-plastic NFD and TFD models are designed for implementation in computer codes using the discrete-element method (DEM) for granular-flow simulations. The model is shown to be accurate and is validated against nonlinear elasto-plastic finite-element analysis.
Formulation, Implementation and Validation of a Two-Fluid model in a Fuel Cell CFD Code
Kunal Jain, Vernon Cole, Sanjiv Kumar and N. Vaidya
2008-11-01
Water management is one of the main challenges in PEM Fuel Cells. While water is essential for membrane electrical conductivity, excess liquid water leads to ooding of catalyst layers. Despite the fact that accurate prediction of two-phase transport is key for optimal water management, understanding of the two-phase transport in fuel cells is relatively poor. Wang et. al. [1], [2] have studied the two-phase transport in the channel and diffusion layer separately using a multiphase mixture model. The model fails to accurately predict saturation values for high humidity inlet streams. Nguyen et. al. [3] developed a two-dimensional, two-phase, isothermal, isobaric, steady state model of the catalyst and gas diffusion layers. The model neglects any liquid in the channel. Djilali et. al. [4] developed a three-dimensional two-phase multicomponent model. The model is an improvement over previous models, but neglects drag between the liquid and the gas phases in the channel. In this work, we present a comprehensive two- fluid model relevant to fuel cells. Models for two-phase transport through Channel, Gas Diffusion Layer (GDL) and Channel-GDL interface, are discussed. In the channel, the gas and liquid pressures are assumed to be same. The surface tension effects in the channel are incorporated using the continuum surface force (CSF) model. The force at the surface is expressed as a volumetric body force and added as a source to the momentum equation. In the GDL, the gas and liquid are assumed to be at different pressures. The difference in the pressures (capillary pressure) is calculated using an empirical correlations. At the Channel-GDL interface, the wall adhesion affects need to be taken into account. SIMPLE-type methods recast the continuity equation into a pressure-correction equation, the solution of which then provides corrections for velocities and pressures. However, in the two-fluid model, the presence of two phasic continuity equations gives more freedom and
NASA Astrophysics Data System (ADS)
Maraqa, Munjed A.; Zhao, Xianda; Lee, Jae-ug; Allan, Fathi; Voice, Thomas C.
2011-07-01
Sorption of dimethyl phthalate (DMP), diethyl phthalate (DEP) and dipropyl phthalate (DPP) to two soil materials that vary in organic matter content was investigated using miscible displacement experiments under saturated flow conditions. Generated breakthrough curves (BTCs) were inversely simulated using linear, equilibrium sorption (LE), nonlinear, equilibrium sorption (NL), linear, first-order nonequilibrium sorption (LFO), linear, radial diffusion (LRD), and nonlinear, first-order nonequilibrium sorption (NFO) models. The Akaike information criterion was utilized to determine the preferred model. The LE model could not adequately describe phthalate ester (PE) BTCs in higher organic matter soil or for more hydrophobic PEs. The LFO and LRD models adequately described the BTCs but a slight improvement in curve-fitting was gained in some cases when the NFO model was used. However, none of the models could properly describe the desorptive tail of DPP for the high organic matter soil. Transport of DPP through this soil was adequately predicted when degradation or sorption hysteresis was considered. Using the optimized parameter values along with values reported by others it was shown that the organic carbon distribution coefficient ( Koc) of PEs correlates well with the octanol/water partition coefficient ( Kow). Also, a strong relationship was found between the first-order sorption rate coefficient normalized to injection pulse size and compound residence time. A similar trend of timescale dependence was found for the rate parameter in the radial diffusion model. Results also revealed that the fraction of instantaneous sorption sites is dependent on Kow and appears to decrease with the increase in the sorption rate parameter.
Freed, Alan D.; Einstein, Daniel R.; Vesely, Ivan
2005-11-01
Most soft tissues possess an oriented architecture of collagen fiber bundles, conferring both anisotropy and nonlinearity to their elastic behavior. Transverse isotropy has often been assumed for a subset of these tissues that have a single macroscopically-identifiable preferred fiber direction. Micro-structural studies, however, suggest that, in some tissues, collagen fibers are approximately normally distributed about a mean preferred fiber direction. Structural constitutive equations that account for this dispersion of fibers have been shown to capture the mechanical complexity of these tissues quite well. Such descriptions, however, are computationally cumbersome for two-dimensional (2D) fiber distributions, let alone for fully three-dimensional (3D) fiber populations. In this paper, we develop a new constitutive law for such tissues, based on a novel invariant theory for dispersed transverse isotropy. The invariant theory is based on a novel closed-form ''splay invariant'' that can easily handle 3D fiber populations, and that only requires a single parameter in the 2D case. The model is polyconvex and fits biaxial data for aortic valve tissue as accurately as the standard structural model. Modification of the fiber stress-strain law requires no re-formulation of the constitutive tangent matrix, making the model flexible for different types of soft tissues. Most importantly, the model is computationally expedient in a finite-element analysis, demonstrated by modeling a bioprosthetic heart valve.
Fine-tuning of DDES and IDDES formulations to the k-ω shear stress transport model
NASA Astrophysics Data System (ADS)
Gritskevich, M. S.; Garbaruk, A. V.; Menter, F. R.
2013-06-01
Modifications are proposed of two recently developed hybrid CFD (computational fluid dynamics) strategies, Delayed Detached Eddy Simulation (DDES), and DDES with Improved wall-modeling capability (IDDES). The modifications are aimed at fine-tuning of these approaches to the k-ω SST (shear stress transport) background RANS (Reynolds-averaged Navier-Stokes) model. The first one includes recalibrated empirical constants in the shielding function of the Spalart-Allmaras (SA) based DDES which are shown to be suboptimal (not providing a needed level of elimination of the Model Stress Depletion (MSD)) for the SST-based DDES model. For the SST-IDDES variant, in addition to that, a simplification of the original SA-based formulation is proposed, which does not cause any visible degradation of the model performance. Both modifications are extensively tested on a range of attached and separated flows (developed channel, backward-facing step, periodic hills, wall-mounted hump, and hydrofoil with trailing edge separation).
Formulation of an experimental substructure model using a Craig-Bampton based transmission simulator
Kammer, Daniel C.; Allen, Matthew S.; Mayes, Randall L.
2015-09-26
An experimental–analytical substructuring is attractive when there is motivation to replace one or more system subcomponents with an experimental model. This experimentally derived substructure can then be coupled to finite element models of the rest of the structure to predict the system response. The transmission simulator method couples a fixture to the component of interest during a vibration test in order to improve the experimental model for the component. The transmission simulator is then subtracted from the tested system to produce the experimental component. This method reduces ill-conditioning by imposing a least squares fit of constraints between substructure modal coordinatesmore » to connect substructures, instead of directly connecting physical interface degrees of freedom. This paper presents an alternative means of deriving the experimental substructure model, in which a Craig–Bampton representation of the transmission simulator is created and subtracted from the experimental measurements. The corresponding modal basis of the transmission simulator is described by the fixed-interface modes, rather than free modes that were used in the original approach. Moreover, these modes do a better job of representing the shape of the transmission simulator as it responds within the experimental system, leading to more accurate results using fewer modes. The new approach is demonstrated using a simple finite element model based example with a redundant interface.« less
Formulation of an experimental substructure model using a Craig-Bampton based transmission simulator
Kammer, Daniel C.; Allen, Matthew S.; Mayes, Randall L.
2015-09-26
An experimental–analytical substructuring is attractive when there is motivation to replace one or more system subcomponents with an experimental model. This experimentally derived substructure can then be coupled to finite element models of the rest of the structure to predict the system response. The transmission simulator method couples a fixture to the component of interest during a vibration test in order to improve the experimental model for the component. The transmission simulator is then subtracted from the tested system to produce the experimental component. This method reduces ill-conditioning by imposing a least squares fit of constraints between substructure modal coordinates to connect substructures, instead of directly connecting physical interface degrees of freedom. This paper presents an alternative means of deriving the experimental substructure model, in which a Craig–Bampton representation of the transmission simulator is created and subtracted from the experimental measurements. The corresponding modal basis of the transmission simulator is described by the fixed-interface modes, rather than free modes that were used in the original approach. Moreover, these modes do a better job of representing the shape of the transmission simulator as it responds within the experimental system, leading to more accurate results using fewer modes. The new approach is demonstrated using a simple finite element model based example with a redundant interface.
Boundary conditions and the generalized metric formulation of the double sigma model
NASA Astrophysics Data System (ADS)
Ma, Chen-Te
2015-09-01
Double sigma model with strong constraints is equivalent to the ordinary sigma model by imposing a self-duality relation. The gauge symmetries are the diffeomorphism and one-form gauge transformation with the strong constraints. We consider boundary conditions in the double sigma model from three ways. The first way is to modify the Dirichlet and Neumann boundary conditions with a fully O (D, D) description from double gauge fields. We perform the one-loop β function for the constant background fields to find low-energy effective theory without using the strong constraints. The low-energy theory can also have O (D, D) invariance as the double sigma model. The second way is to construct different boundary conditions from the projectors. The third way is to combine the antisymmetric background field with field strength to redefine an O (D, D) generalized metric. We use this generalized metric to reconstruct a consistent double sigma model with the classical and quantum equivalence.
Garrido-Balsells, José María; Jurado-Navas, Antonio; Paris, José Francisco; Castillo-Vazquez, Miguel; Puerta-Notario, Antonio
2015-03-01
In this paper, a novel and deeper physical interpretation on the recently published Málaga or ℳ statistical distribution is provided. This distribution, which is having a wide acceptance by the scientific community, models the optical irradiance scintillation induced by the atmospheric turbulence. Here, the analytical expressions previously published are modified in order to express them by a mixture of the known Generalized-K and discrete Binomial and Negative Binomial distributions. In particular, the probability density function (pdf) of the ℳ model is now obtained as a linear combination of these Generalized-K pdf, in which the coefficients depend directly on the parameters of the ℳ distribution. In this way, the Málaga model can be physically interpreted as a superposition of different optical sub-channels each of them described by the corresponding Generalized-K fading model and weighted by the ℳ dependent coefficients. The expressions here proposed are simpler than the equations of the original ℳ model and are validated by means of numerical simulations by generating ℳ -distributed random sequences and their associated histogram. This novel interpretation of the Málaga statistical distribution provides a valuable tool for analyzing the performance of atmospheric optical channels for every turbulence condition. PMID:25836855
Formulation of an experimental substructure model using a Craig-Bampton based transmission simulator
NASA Astrophysics Data System (ADS)
Kammer, Daniel C.; Allen, Mathew S.; Mayes, Randy L.
2015-12-01
Experimental-analytical substructuring is attractive when there is motivation to replace one or more system subcomponents with an experimental model. This experimentally derived substructure can then be coupled to finite element models of the rest of the structure to predict the system response. The transmission simulator method couples a fixture to the component of interest during a vibration test in order to improve the experimental model for the component. The transmission simulator is then subtracted from the tested system to produce the experimental component. The method reduces ill-conditioning by imposing a least squares fit of constraints between substructure modal coordinates to connect substructures, instead of directly connecting physical interface degrees of freedom. This paper presents an alternative means of deriving the experimental substructure model, in which a Craig-Bampton representation of the transmission simulator is created and subtracted from the experimental measurements. The corresponding modal basis of the transmission simulator is described by the fixed-interface modes, rather than free modes that were used in the original approach. These modes do a better job of representing the shape of the transmission simulator as it responds within the experimental system, leading to more accurate results using fewer modes. The new approach is demonstrated using a simple finite element model based example with a redundant interface.
A model for the human cornea: constitutive formulation and numerical analysis.
Pandolfi, A; Manganiello, F
2006-11-01
Abstract The human cornea (the external lens of the eye) has the macroscopic structure of a thin shell, originated by the organization of collagen lamellae parallel to the middle surface of the shell. The lamellae, composed of bundles of collagen fibrils, are responsible for the experimentally observed anisotropy of the cornea. Anomalies in the fibril structure may explain the changes in the mechanical behavior of the tissue observed in pathologies such as keratoconus. We employ a fiber-matrix constitutive model and propose a numerical model for the human cornea that is able to account for its mechanical behavior in healthy conditions or in the presence of keratoconus under increasing values of the intraocular pressure. The ability of our model to reproduce the behavior of the human cornea opens a promising perspective for the numerical simulation of refractive surgery. PMID:16444515
Mathematical modeling of cement paste microstructure by mosaic pattern Part I. Formulation
Xi, Y.; Tennis, P.D.; Jennings, H.M.
1996-08-01
This paper develops a mathematical model using mosaic patterns to characterize structural features of complex, multiphase and multidimensional microstructures, such as those for cement paste. A multiphase microstructure can be characterized by {ital m} independent parameters: the first {ital m}{minus}1 parameters are equivalent to the volume fractions of the phases, while the final parameter describes the grain size, and thus, the spatial arrangement of the microstructure. An evaluation procedure for the parameters is given; they can be evaluated based on a 2D image, and then the 3D microstructure can be simulated by the present model. The relationship among the model parameters and material parameters, such as water-to-cement ratio and particle size distribution, are also established. {copyright} {ital 1996 Materials Research Society.}
Dunne, John P.; John, Jasmin G.; Adcroft, Alistair J.; Griffies, Stephen M.; Hallberg, Robert W.; Shevalikova, Elena; Stouffer, Ronald J.; Cooke, William; Dunne, Krista A.; Harrison, Matthew J.; Krasting, John P.; Malyshev, Sergey L.; Milly, P.C.D.; Phillipps, Peter J.; Sentman, Lori A.; Samuels, Bonita L.; Spelman, Michael J.; Winton, Michael; Wittenberg, Andrew T.; Zadeh, Niki
2012-01-01
We describe the physical climate formulation and simulation characteristics of two new global coupled carbon-climate Earth System Models, ESM2M and ESM2G. These models demonstrate similar climate fidelity as the Geophysical Fluid Dynamics Laboratory's previous CM2.1 climate model while incorporating explicit and consistent carbon dynamics. The two models differ exclusively in the physical ocean component; ESM2M uses Modular Ocean Model version 4.1 with vertical pressure layers while ESM2G uses Generalized Ocean Layer Dynamics with a bulk mixed layer and interior isopycnal layers. Differences in the ocean mean state include the thermocline depth being relatively deep in ESM2M and relatively shallow in ESM2G compared to observations. The crucial role of ocean dynamics on climate variability is highlighted in the El Niño-Southern Oscillation being overly strong in ESM2M and overly weak ESM2G relative to observations. Thus, while ESM2G might better represent climate changes relating to: total heat content variability given its lack of long term drift, gyre circulation and ventilation in the North Pacific, tropical Atlantic and Indian Oceans, and depth structure in the overturning and abyssal flows, ESM2M might better represent climate changes relating to: surface circulation given its superior surface temperature, salinity and height patterns, tropical Pacific circulation and variability, and Southern Ocean dynamics. Our overall assessment is that neither model is fundamentally superior to the other, and that both models achieve sufficient fidelity to allow meaningful climate and earth system modeling applications. This affords us the ability to assess the role of ocean configuration on earth system interactions in the context of two state-of-the-art coupled carbon-climate models.
Biopsychosocial Formulation: Recognizing Educational Shortcomings
ERIC Educational Resources Information Center
McClain, Tina; O'Sullivan, Patricia S.; Clardy, James A.
2004-01-01
Objective: Since Engel introduced the biopsychosocial model, it has been extensively examined. The authors expect psychiatrists to formulate cases using the biopsychosocial model. However, resident psychiatrists' ability to generate formulations using this model has received little attention. Methods: The authors evaluated resident biopsychosocial…
A lateral boundary formulation for multi-level prediction models. [numerical weather forecasting
NASA Technical Reports Server (NTRS)
Davies, H. C.
1976-01-01
A method is proposed for treating the lateral boundaries of a limited-area weather prediction model. The method involves the relaxation of the interior flow in the vicinity of the boundary to the external fully prescribed flow. Analytical and numerical results obtained with a linearized multilevel model confirm the effectiveness of this computationally effective method. The method is shown to give an adequate representation of outgoing gravity waves with and without an ambient shear flow and to allow the substantially undistorted transmission of geostrophically balanced flow out of the interior of the limited domain.
A Comment on the New Formulation of a Many-Level Shell Model
NASA Astrophysics Data System (ADS)
Yasumoto, S.; Shimizu, Y. R.
2003-11-01
In order to construct a set of orthonormalized basis vectors in a many-level shell model space, we introduced a new type of CFP in a previous paper [K. Takada, M. Sato and S. Yasumoto, Prog. Theor. Phys. 104 (2000), 173]. There, we also presented one of its analytic representations. In this paper, we improve that representation by making it much simpler and applicable to the case of the five-level. Using this improved representation, it is possible to develop a general-use computer program for the shell-model calculation.
Modelling and calculation of flotation process in one-dimensional formulation
NASA Astrophysics Data System (ADS)
Amanbaev, Tulegen; Tilleuov, Gamidulla; Tulegenova, Bibigul
2016-08-01
In the framework of the assumptions of the mechanics of the multiphase media is constructed a mathematical model of the flotation process in the dispersed mixture of liquid, solid and gas phases, taking into account the degree of mineralization of the surface of the bubbles. Application of the constructed model is demonstrated on the example of one-dimensional stationary flotation and it is shown that the equations describing the process of ascent of the bubbles are singularly perturbed ("rigid"). The effect of size and concentration of bubbles and the volumetric content of dispersed particles on the flotation process are analyzed.
Shea, Munyi; Yang, Lawrence H.; Leong, Frederick T. L.
2011-01-01
Culture shapes the nature, experience, and expression of psychopathology and help-seeking behavior across ethnically diverse groups. Although the study of psychopathology among Asian Americans has advanced, clinicians remain in need of culturally appropriate tools for the assessment and diagnosis of severe mental disorders including psychotic symptoms among Asian Americans. In this article, we present a brief overview of two culturally relevant conceptual tools: a) the Cultural Formulation Model, and b) the Multicultural Case Conceptualization approach. We use a case scenario to illustrate the integration of these two approaches in providing culturally responsive clinical conceptualization, assessment and treatment of a Korean American immigrant suffering from prominent psychiatric symptoms. We intend this discussion to engender further empirical work to advance our knowledge of the manifestation and experience of severe mental illness including psychotic disorders among Asian Americans, and contribute to culturally competent prevention and intervention of chronic and persistent mental illness within this group. PMID:21603157
NASA Technical Reports Server (NTRS)
Castruccio, P. A.; Loats, H. L., Jr.; Fowler, T. R.
1977-01-01
Methods for the reduction of remotely sensed data and its application in hydrologic land use assessment, surface water inventory, and soil property studies are presented. LANDSAT data is used to provide quantitative parameters and coefficients to construct watershed transfer functions for a hydrologic planning model aimed at estimating peak outflow from rainfall inputs.
The impact of a boundary layer height formulation on the GEOS-5 model climate
NASA Astrophysics Data System (ADS)
McGrath-Spangler, E. L.
2016-04-01
Planetary boundary layer (PBL) processes are important for the estimation of surface-atmosphere exchanges that impact global climate. One way of characterizing the strength of these processes is the PBL depth. In the Goddard Earth Observing System (GEOS-5) atmospheric general circulation model, the PBL depth is also used in calculating the turbulent length scale, which, in turn, is used in estimating the turbulence and vertical mixing within the model. Therefore, changing the PBL depth definition directly affects the model climate. This study evaluates the climatological model response of two long-term simulations using different PBL depth definitions. The first definition is based on a bulk Richardson number; the second uses a combination of the same bulk Richardson number definition over land plus a definition based on the turbulent eddy diffusion coefficient over water. The two simulations produce different spatiotemporal patterns of temperature, specific humidity, and wind speed related to the differences in turbulence. The largest differences, as expected, are present over water. Due to differences in atmospheric stability, the relationship between the two PBL depth estimates differ among the majority of the oceans and off the west coasts of continents, affecting the climatic response. Due to its optimization of the climatic response while maintaining a realistic diurnal cycle of PBL depth, the mixed PBL depth configuration is preferred.
Mayhew, Emily; Schmidt, Shelly; Lee, Soo-Yeun
2016-07-01
In a novel approach to formulation, the flash descriptive profiling technique Napping-Ultra Flash Profile (Napping-UFP) was used to characterize a wide range of commercial caramel corn products. The objectives were to identify product categories, develop model systems based on product categories, and correlate analytical parameters with sensory terms generated through the Napping-UFP exercise. In one 2 h session, 12 panelists participated in 4 Napping-UFP exercises, describing and grouping, on a 43×56 cm paper sheet, 12 commercial caramel corn samples by degree of similarity, globally and in terms of aroma-by-mouth, texture, and taste. The coordinates of each sample's placement on the paper sheet and descriptive terms generated by the panelists were used to conduct Multiple Factor Analysis (MFA) and hierarchical clustering of the samples. Strong trends in the clustering of samples across the 4 Napping-UFP exercises resulted in the determination of 3 overarching types of commercial caramel corn: "small-scale dark" (typified by burnt, rich caramel corn), "large-scale light" (typified by light and buttery caramel corn), and "large-scale dark" (typified by sweet and molasses-like caramel corn). Representative samples that best exemplified the properties of each category were used as guides in the formulation of 3 model systems that represent the spread of commercial caramel corn products. Analytical testing of the commercial products, including aw measurement, moisture content determination, and thermal characterization via differential scanning calorimetry, were conducted and results related to sensory descriptors using Spearman's correlation. PMID:27249670
Kish-Catalone, Tina; Pal, Ranajit; Parrish, John; Rose, Nicholas; Hocker, Lindsey; Hudacik, Lauren; Reitz, Marvin; Gallo, Robert; Devico, Anthony
2007-01-01
A potential strategy to combat the worldwide AIDS epidemic is to develop a vaginal microbicide that prevents the sexual transmission of HIV-1. One approach for preventing vaginal HIV transmission is to block the viral coreceptor CCR5 with naturally occurring chemokine ligands. In this study, we used a cynomolgus macaque model to evaluate whether a variant of the CCR5 ligand RANTES (-2 RANTES), tested alone or in a nonphospholipid liposome carrier (Novasomes 7474), blocks vaginal challenge with a CCR5-tropic simian/human immunodeficiency virus (SHIV(162P3)). When tested in vitro, the synthetic chemokine potently inhibited SHIV(162P3) infection of cynomolgus macaque peripheral blood mononuclear cells (PBMC). Colposcopic examinations of treated animals and histological examination of cervicovaginal biopsies showed minimal signs of tissue inflammation following vaginal application of Novasomes 7474, -2 RANTES formulated in Novasomes 7474, or -2 RANTES alone. Following vaginal challenge with SHIV(162P3), complete protection was observed in four of six animals treated vaginally with -2 RANTES (0.13 mM) formulated in Novasomes 7474. However, the same proportion of animals was protected by treatment with Novasomes 7474 carrier alone. Two of five animals treated with 0.5 mM -2 RANTES in PBS were protected from infection. Further, all animals were infected when treated with lower chemokine concentrations. These findings indicate that natural CCR5 ligands may have limited efficacy in stringent nonhuman primate models for vaginal infection. In comparison, liposomal agents such as Novasomes 7474 provide comparatively robust protection against vaginal transmission. PMID:17263630
Moving Towards Integrated Policy Formulation and Evaluation: The Green Economy Model
NASA Astrophysics Data System (ADS)
Bassi, Andrea M.
2015-12-01
The mainstreaming of concepts related to the Green Economy, an action-oriented approach to reach sustainable development, has increased demands for integrated models that can shed light on the complex relations existing across social, economic and environmental indicators. A gap exists, whereby our thinking is rapidly evolving, but the tools available are still in the vast majority of cases sectorial, leading to planning processes taking place in silos. To avoid the emergence of side effects, and anticipate future threats and opportunities, a more systemic approach is needed. The Green Economy Model (GEM) was created taking into account four main capitals and their interconnections: physical capital, human capital, social capital and natural capital. The application of GEM in 10 countries has shown its capability to coherently represent reality and generate results that can more effectively inform decision making.
Pham, VT.; Silva, L.; Digonnet, H.; Combeaud, C.; Billon, N.; Coupez, T.
2011-05-04
The objective of this work is to model the viscoelastic behaviour of polymer from the solid state to the liquid state. With this objective, we perform experimental tensile tests and compare with simulation results. The chosen polymer is a PMMA whose behaviour depends on its temperature. The computation simulation is based on Navier-Stokes equations where we propose a mixed finite element method with an interpolation P1+/P1 using displacement (or velocity) and pressure as principal variables. The implemented technique uses a mesh composed of triangles (2D) or tetrahedra (3D). The goal of this approach is to model the viscoelastic behaviour of polymers through a fluid-structure coupling technique with a multiphase approach.
The numerical integration and 3-D finite element formulation of a viscoelastic model of glass
Chambers, R.S.
1994-08-01
The use of glasses is widespread in making hermetic, insulating seals for many electronic components. Flat panel displays and fiber optic connectors are other products utilizing glass as a structural element. When glass is cooled from sealing temperatures, residual stresses are generated due to mismatches in thermal shrinkage created by the dissimilar material properties of the adjoining materials. Because glass is such a brittle material at room temperature, tensile residual stresses must be kept small to ensure durability and avoid cracking. Although production designs and the required manufacturing process development can be deduced empirically, this is an expensive and time consuming process that does not necessarily lead to an optimal design. Agile manufacturing demands that analyses be used to reduce development costs and schedules by providing insight and guiding the design process through the development cycle. To make these gains, however, viscoelastic models of glass must be available along with the right tool to use them. A viscoelastic model of glass can be used to simulate the stress and volume relaxation that occurs at elevated temperatures as the molecular structure of the glass seeks to equilibrate to the state of the supercooled liquid. The substance of the numerical treatment needed to support the implementation of the model in a 3-D finite element program is presented herein. An accurate second-order, central difference integrator is proposed for the constitutive equations, and numerical solutions are compared to those obtained with other integrators. Inherent convergence problems are reviewed and fixes are described. The resulting algorithms are generally applicable to the broad class of viscoelastic material models. First-order error estimates are used as a basis for developing a scheme for automatic time step controls, and several demonstration problems are presented to illustrate the performance of the methodology.
Final Report for Formulation of Moist Dynamics and Physics for Future Climate Models
Celal S. Konor
2008-04-30
In this project, one of our goals is to develop atmospheric models, in which innovative ideas on improving the quality of moisture predictions can be tested. Our other goal is to develop an explicit time integration scheme based on the multi-point differencing (MED) that does the same job as an implicit trapezoidal scheme but uses information only from limited number of grid points. Below we discuss the work performed at UCLA toward these goals during the funding period indicated above.
A mixed finite element-finite volume formulation of the Black-Oil model
Bergamaschi, L.; Mantica, S.; Manzini, G.
1999-01-01
In this paper the authors mainly address the compressible model where three independent components (oil, gas, and water) form the three phases (liquid, vapor, and aqua) present in the reservoir. This model is usually known under the name of Black-Oil, and its main feature is the description of mass-exchange processes between all phases. In this paper a sequential coupling of mixed finite element and shock-capturing finite volume techniques is proposed, in order to numerically solve the system of partial differential equations arising from the Black-Oil model. The Brezzi-Douglas-Marini space of degree one is used to approximate the Darcy`s velocity in the parabolic-type pressure equation, while the system of mass conservation laws is solved by a higher order Godunov-type scheme, here extended to triangle-based unstructured grids. Numerical results on 1-D and 2-D test cases prove the effectiveness and the robustness of the coupling, which seems particularly suited to handling high heterogeneities and at the same time accurately resolving steep gradients without spurious oscillations.
Odenthal, Tim; Smeets, Bart; Van Liedekerke, Paul; Tijskens, Engelbert; Van Oosterwyck, Hans; Ramon, Herman
2013-01-01
Adhesion governs to a large extent the mechanical interaction between a cell and its microenvironment. As initial cell spreading is purely adhesion driven, understanding this phenomenon leads to profound insight in both cell adhesion and cell-substrate interaction. It has been found that across a wide variety of cell types, initial spreading behavior universally follows the same power laws. The simplest cell type providing this scaling of the radius of the spreading area with time are modified red blood cells (RBCs), whose elastic responses are well characterized. Using a mechanistic description of the contact interaction between a cell and its substrate in combination with a deformable RBC model, we are now able to investigate in detail the mechanisms behind this universal power law. The presented model suggests that the initial slope of the spreading curve with time results from a purely geometrical effect facilitated mainly by dissipation upon contact. Later on, the spreading rate decreases due to increasing tension and dissipation in the cell's cortex as the cell spreads more and more. To reproduce this observed initial spreading, no irreversible deformations are required. Since the model created in this effort is extensible to more complex cell types and can cope with arbitrarily shaped, smooth mechanical microenvironments of the cells, it can be useful for a wide range of investigations where forces at the cell boundary play a decisive role. PMID:24146605
O'Hara, Thomas; Virág, László; Varró, András; Rudy, Yoram
2011-05-01
Cellular electrophysiology experiments, important for understanding cardiac arrhythmia mechanisms, are usually performed with channels expressed in non myocytes, or with non-human myocytes. Differences between cell types and species affect results. Thus, an accurate model for the undiseased human ventricular action potential (AP) which reproduces a broad range of physiological behaviors is needed. Such a model requires extensive experimental data, but essential elements have been unavailable. Here, we develop a human ventricular AP model using new undiseased human ventricular data: Ca(2+) versus voltage dependent inactivation of L-type Ca(2+) current (I(CaL)); kinetics for the transient outward, rapid delayed rectifier (I(Kr)), Na(+)/Ca(2+) exchange (I(NaCa)), and inward rectifier currents; AP recordings at all physiological cycle lengths; and rate dependence and restitution of AP duration (APD) with and without a variety of specific channel blockers. Simulated APs reproduced the experimental AP morphology, APD rate dependence, and restitution. Using undiseased human mRNA and protein data, models for different transmural cell types were developed. Experiments for rate dependence of Ca(2+) (including peak and decay) and intracellular sodium ([Na(+)](i)) in undiseased human myocytes were quantitatively reproduced by the model. Early afterdepolarizations were induced by I(Kr) block during slow pacing, and AP and Ca(2+) alternans appeared at rates >200 bpm, as observed in the nonfailing human ventricle. Ca(2+)/calmodulin-dependent protein kinase II (CaMK) modulated rate dependence of Ca(2+) cycling. I(NaCa) linked Ca(2+) alternation to AP alternans. CaMK suppression or SERCA upregulation eliminated alternans. Steady state APD rate dependence was caused primarily by changes in [Na(+)](i), via its modulation of the electrogenic Na(+)/K(+) ATPase current. At fast pacing rates, late Na(+) current and I(CaL) were also contributors. APD shortening during restitution was
NASA Technical Reports Server (NTRS)
Ramachandran, N.
1999-01-01
Crystal growth from the vapor phase has various advantages over melt growth. The main advantage is from a lower processing temperature which makes the process more amenable in instances where the melting temperature of the crystal is high. Other benefits stem from the inherent purification mechanism in the process due to differences in the vapor pressures of the native elements and impurities, and the enhanced interfacial morphological stability during the growth process. Further, the implementation of PVT growth in closed ampoules affords experimental simplicity with minimal needs for complex process control which makes it an ideal candidate for space investigations in systems where gravity tends to have undesirable effects on the growth process. Bulk growth of wide band gap II-VI semiconductors by physical vapor transport has been developed and refined over the past several years at NASA MSFC. Results from a modeling study of PVT crystal growth of ZnSe are reported in this paper. The PVT process is numerically investigated using both two-dimensional and fully three-dimensional formulation of the governing equations and associated boundary conditions. Both the incompressible Boussinesq approximation and the compressible model are tested to determine the influence of gravity on the process and to discern the differences between the two approaches. The influence of a residual gas is included in the models. The results show that both the incompressible and compressible approximations provide comparable results and the presence of a residual gas tends to measurably reduce the mass flux in the system. Detailed flow, thermal and concentration profiles will be provided in the final manuscript along with computed heat and mass transfer rates. Comparisons with the 1-D model will also be provided. The effect of gravity on the process from numerical computations shows subtle effects although experimental evidence from vertically and horizontally grown samples show dramatic
Plumb, A Philip; Rowe, Raymond C; York, Peter; Doherty, Christopher
2002-09-01
The aim of this study was to investigate the effect of experimental design strategy on the modeling of a film coating formulation by artificial neural networks (ANNs). Box-Behnken, central composite and pseudo-random designs of 102, 90 and 100 simulated records, respectively were used to train a multilayer perceptron (MLP) ANN comprising six input and two output nodes separated by a single hidden layer of five nodes. Network over-training was limited by using a test set of 40 pseudo-randomly distributed records. The models were validated using a set of 60 pseudo-randomly distributed records. Crack velocity was highly curved with respect to pigment particle size and size distribution. Similarly, film opacity was highly curved in response to pigment concentration and film thickness. The Box-Behnken and central composite designs generated models that were unable to predict crack velocity and showed extensive bias in prediction of film opacity. The pseudo-random design was unable to predict crack velocity of the test data set but yielded acceptable predictions for the validation set. Film opacity was well predicted by the pseudo-random design model. The poor predictive ability of the Box-Behnken and central composite models was attributed to poor interpolation of the high curvature of the response surfaces. In contrast, the pseudo-random design mapped the interior of the design space allowing improved interpolation and predictive ability. It is concluded that Box-Behnken and central composite experimental designs are inappropriate for ANN modeling of highly curved responses and that extensive internal mapping of the design space is essential to generate predictive ANN models. PMID:12208458
NASA Astrophysics Data System (ADS)
Maupin, Valerie; Näsholm, Sven Peter; Schweitzer, Johannes; Gibbons, Steven J.
2016-04-01
We recently advocated using the reflectivity method, also known as the wavenumber integration method or fast-field program, to model atmospheric infrasound propagation at regional distances. The advantage of the reflectivity method is its ability to model the full wavefield, including diffractive effects with head waves and shadow zone arrivals, in a broad frequency range but still at a relatively low computational cost. Attenuation can easily be included, giving the possibility to analyse relative amplitudes and frequency content of the different arrivals. It has clear advantages compared with ray theory in terms of predicting phases considering the particular frequent occurrence of shadow zone arrivals in infrasound observations. Its main limitation, at least in the traditional form of the method, lies in the fact that it can only handle range-independent models. We presented earlier some reflectivity method simulations of an observed accidental explosion in Norway. Wind intensity and direction are non-negligible parameters for infrasound propagation and these are appropriately taken into account in most infrasound ray-tracing codes. On the other hand, in the previous reflectivity simulations wind was taken into account only through the effective sound speed approximation where the horizontal projection of the wind field is added to the adiabatic sound speed profiles. This approximation is appropriate for dominantly horizontal propagation but can give incorrect arrival times and shadow zone locations for waves which have a significant portion of their propagation path at more vertical incidence, like thermospheric arrivals. We present here how we have modified the original reflectivity algorithm in order to take the wind into account in a more correct fashion, and how this improvement influences the synthetics.
On the formulation of a minimal uncertainty model for robust control with structured uncertainty
NASA Technical Reports Server (NTRS)
Belcastro, Christine M.; Chang, B.-C.; Fischl, Robert
1991-01-01
In the design and analysis of robust control systems for uncertain plants, representing the system transfer matrix in the form of what has come to be termed an M-delta model has become widely accepted and applied in the robust control literature. The M represents a transfer function matrix M(s) of the nominal closed loop system, and the delta represents an uncertainty matrix acting on M(s). The nominal closed loop system M(s) results from closing the feedback control system, K(s), around a nominal plant interconnection structure P(s). The uncertainty can arise from various sources, such as structured uncertainty from parameter variations or multiple unsaturated uncertainties from unmodeled dynamics and other neglected phenomena. In general, delta is a block diagonal matrix, but for real parameter variations delta is a diagonal matrix of real elements. Conceptually, the M-delta structure can always be formed for any linear interconnection of inputs, outputs, transfer functions, parameter variations, and perturbations. However, very little of the currently available literature addresses computational methods for obtaining this structure, and none of this literature addresses a general methodology for obtaining a minimal M-delta model for a wide class of uncertainty, where the term minimal refers to the dimension of the delta matrix. Since having a minimally dimensioned delta matrix would improve the efficiency of structured singular value (or multivariable stability margin) computations, a method of obtaining a minimal M-delta would be useful. Hence, a method of obtaining the interconnection system P(s) is required. A generalized procedure for obtaining a minimal P-delta structure for systems with real parameter variations is presented. Using this model, the minimal M-delta model can then be easily obtained by closing the feedback loop. The procedure involves representing the system in a cascade-form state-space realization, determining the minimal uncertainty matrix
Analytical formulation of 2-D aeroelastic model in weak ground effect
NASA Astrophysics Data System (ADS)
Dessi, Daniele; Mastroddi, Franco; Mancini, Simone
2013-10-01
This paper deals with the aeroelastic modeling and analysis of a 2-D oscillating airfoil in ground effect, elastically constrained by linear and torsional springs and immersed in an incompressible potential flow (typical section) at a finite distance from the ground. This work aims to extend Theodorsen theory, valid in an unbounded flow domain, to the case of weak ground effect, i.e., for clearances above half the airfoil chord. The key point is the determination of the aerodynamic loads, first in the frequency domain and then in the time domain, accounting for their dependence on the ground distance. The method of images is exploited in order to comply with the impermeability condition on the ground. The new integral equation in the unknown vortex distribution along the chord and the wake is solved using asymptotic expansions in the perturbation parameter defined as the inverse of the non-dimensional ground clearance of the airfoil. The mathematical model describing the aeroelastic system is transformed from the frequency domain into the time domain and then in a pure differential form using a finite-state aerodynamic approximation (augmented states). The typical section, which the developed theory is applied to, is obtained as a reduced model of a wing box finite element representation, thus allowing comparison with the corresponding aeroelastic analysis carried out by a commercial solver based on a 3-D lifting surface aerodynamic model. Stability (flutter margins) and response of the airfoil both in frequency and time domains are then investigated. In particular, within the developed theory, the solution of the Wagner problem can be directly achieved confirming an asymptotic trend of the aerodynamic coefficients toward the steady-state conditions different from that relative to the unbounded domain case. The dependence of flutter speed and the frequency response functions on ground clearance is highlighted, showing the usefulness of this approach in efficiently
Hamiltonian Formulation of the 5-D Kaluza-Klein Model and Test-Particle Motion
NASA Astrophysics Data System (ADS)
Lacquaniti, Valentino; Montani, Giovanni
2008-09-01
We examine the ADM reformulation of the 5-D KK model: the dimensional reduction is provided to commute with the ADM splitting and we show how the time component of the gauge vector is given by combination of the Lagrangian multipliers for the 5-D gravitational field. We consider 5D particles motion and after dimensional reduction the definition of charge is recovered within electrodynamic coupling. A time-varying fine structure constant is recognized because an extra scalar field is present in the 4-D theory.
NASA Technical Reports Server (NTRS)
Wind, G.; DaSilva, A. M.; Norris, P. M.; Platnick, S.
2013-01-01
In this paper we describe a general procedure for calculating synthetic sensor radiances from variable output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint, the algorithm takes explicit account of the model subgrid variability, in particular its description of the probability density function of total water (vapor and cloud condensate.) The simulated sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies.We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products). We focus on clouds because they are very important to model development and improvement.
NASA Technical Reports Server (NTRS)
Koster, Randal D.; Mahanama, P. P.
2012-01-01
Key to translating soil moisture memory into subseasonal precipitation and air temperature forecast skill is a realistic treatment of evaporation in the forecast system used - in particular, a realistic treatment of how evaporation responds to variations in soil moisture. The inherent soil moisture-evaporation relationships used in today's land surface models (LSMs), however, arguably reflect little more than guesswork given the lack of evaporation and soil moisture data at the spatial scales represented by regional and global models. Here we present a new approach for evaluating this critical aspect of LSMs. Seasonally averaged precipitation is used as a proxy for seasonally-averaged soil moisture, and seasonally-averaged air temperature is used as a proxy for seasonally-averaged evaporation (e.g., more evaporative cooling leads to cooler temperatures) the relationship between historical precipitation and temperature measurements accordingly mimics in certain important ways nature's relationship between soil moisture and evaporation. Additional information on the relationship is gleaned from joint analysis of precipitation and streamflow measurements. An experimental framework that utilizes these ideas to guide the development of an improved soil moisture-evaporation relationship is described and demonstrated.
Phelan, J.M.; Webb, S.W.
1997-06-01
The fate and transport of chemical signature molecules that emanate from buried landmines is strongly influenced by physical chemical properties and by environmental conditions of the specific chemical compounds. Published data have been evaluated as the input parameters that are used in the simulation of the fate and transport processes. A one-dimensional model developed for screening agricultural pesticides was modified and used to simulate the appearance of a surface flux above a buried landmine, estimate the subsurface total concentration, and show the phase specific concentrations at the ground surface. The physical chemical properties of TNT cause a majority of the mass released to the soil system to be bound to the solid phase soil particles. The majority of the transport occurs in the liquid phase with diffusion and evaporation driven advection of soil water as the primary mechanisms for the flux to the ground surface. The simulations provided herein should only be used for initial conceptual designs of chemical pre-concentration subsystems or complete detection systems. The physical processes modeled required necessary simplifying assumptions to allow for analytical solutions. Emerging numerical simulation tools will soon be available that should provide more realistic estimates that can be used to predict the success of landmine chemical detection surveys based on knowledge of the chemical and soil properties, and environmental conditions where the mines are buried. Additional measurements of the chemical properties in soils are also needed before a fully predictive approach can be confidently applied.
García, José Jaime; Cortés, Daniel Humberto
2007-01-01
Experiments in articular cartilage have shown highly nonlinear stress-strain curves under finite deformations, nonlinear tension-compression response as well as intrinsic viscous effects of the proteoglycan matrix and the collagen fibers. A biphasic viscohyperelastic fibril-reinforced model is proposed here, which is able to describe the intrinsic viscoelasticity of the fibrillar and nonfibrillar components of the solid phase, the nonlinear tension-compression response and the nonlinear stress-strain curves under tension and compression. A viscohyperelastic constitutive equation was used for the matrix and the fibers encompassing, respectively, a hyperelastic function used previously for the matrix and a hyperelastic law used before to represent biological connective tissues. This model, implemented in an updated Lagrangian finite element code, displayed good ability to follow experimental stress-strain equilibrium curves under tension and compression for human humeral cartilage. In addition, curve fitting of experimental reaction force and lateral displacement unconfined compression curves showed that the inclusion of viscous effects in the matrix allows the description of experimental data with material properties for the fibers consistent with experimental tensile tests, suggesting that intrinsic viscous effects in the matrix of articular cartilage plays an important role in the mechanical response of the tissue. PMID:17014853
NASA Astrophysics Data System (ADS)
Müller, S. A.; Joos, F.; Plattner, G.-K.; Edwards, N. R.; Stocker, T. F.
2008-09-01
Observation-based surface ocean Δ14C distributions and regional inventories for excess, bomb-produced radiocarbon are compared with results of two ocean models of intermediate complexity. By applying current descriptions of the air-sea gas exchange the models produce similar column inventories for excess 14C among all basins. This result is robust across a wide range of transport parameter settings, but inconsistent with data-based inventories. In the absence of evidence of fundamentally different gas exchange mechanisms in the North Atlantic than in the other basins, we infer regional North Atlantic 14C inventories which are considerably smaller than previous estimates. The results further suggest that the gas exchange velocity field should be reduced by (19 ± 16)%, which corresponds to a global mean air-sea gas transfer rate for CO2 in seawater of 17.1 ± 3.3 cm h-1, to find good agreement of simulated quantities with a range of data-based metrics.
Cheong, W.; Barton, P.I.
1999-04-01
A mathematical model for the middle vessel batch distillation column (MVC) is developed using the concept of warped time analysis and used to study the qualitative dynamics of the MVC when it is used to separate multicomponent azeotropic mixtures. A limiting analysis is then developed for a MVC with an infinite number of trays, operated under infinite reflux/reboil ratios, under the assumption of linear separation boundaries. It is determined that, under limiting conditions, the distillate product drawn from the MVC is given by the {alpha} limit set of the MVC still pot composition, while the bottoms product drawn from the MVC is given by the {omega} limit set of the MVC still pot composition. The net product composition is determined by taking a convex combination of the two products. The notions of steering the still pot composition, the vector cone of possible motion for the still pot composition, and the equivalency of the MVC to the combined operation of a batch rectifier and a stripper are also explored. The definition of batch distillation regions for the MVC operated at a given value of the middle vessel parameter {lambda}, and the bifurcation of these regions with the variation of {lambda}, are investigated. Lastly, a mathematical model incorporating the concept of warped time is developed for a multivessel column. The MVC can be viewed as a specific case of the multivessel column.
Formulation of an Integrated Model for Freshwater Resources Policy Evaluation in Jordan
NASA Astrophysics Data System (ADS)
Gorelick, S.; Yoon, J.; Gawel, E.; Klauer, B.; Klassert, C. J. A.; Sigel, K.; Tilmant, A.; Lachaut, T.; Avisse, N.; Harou, J. J.; Padula, S.; Mustafa, D.
2014-12-01
Jordan is one of the four water poorest countries in the world. It is a highly vulnerable arid region whose freshwater system is at a tipping point due to the confluence of severely limited water supplies, rapid population growth, refugee influxes, climate change and variability, internal and transboundary competition for shared freshwater resources, and institutional impediments. Our team is engaged in an interdisciplinary effort aimed at developing a new approach to evaluate policies that enhance sustainability of freshwater resource systems. Our work adopts a multi-agent modeling framework that incorporates institutional complexity to evaluate policy instruments for improving water security in Jordan. We are developing this model using a modular approach, integrating biophysical modules that simulate natural and engineered phenomena (e.g., groundwater-surface water flow, reservoir storage, network routing, salt balance, and crop yield) with human modules that represent behavior at multiple scales of decision making. The human modules adopt a multi-agent simulation approach, defining agents as autonomous decision-makers at the government, administrative, organizational, and user levels. Our goal is to construct a suite of policy intervention scenarios that will form the basis for analysis of freshwater sustainability. This work has benefitted from a strong working relationship with leaders of the water sector in Jordan. Our approach and the merit of the policy interventions should have significant transfer value to other water-stressed regions.
Effect of gasoline formulation on the formation of photosmog: a box model study.
Geiger, Herald; Becker, Karl H; Wiesen, Peter
2003-04-01
Based on exhaust gas analyses from the combustion of five different types of gasoline in a passenger car operated on a chassis dynamometer, box model simulations of the irradiation of exhaust/NOx/air mixtures using an established chemical mechanism for a standardized photosmog scenario were performed. The fuel matrix used covered wide fractional ranges for paraffinic, olefinic, and aromatic hydrocarbons. Two fuels also contained methyl tertiary butyl ether (MTBE). The different O3 profiles calculated for each run were compared and interpreted. The O3 levels obtained were strongly influenced by the exhaust gas concentrations of aromatic and olefinic hydrocarbons. The higher exhaust content of these compounds caused higher O3 production in the smog system investigated. The conclusion of the present study is that the composition of gasoline cannot be taken directly for the estimation of the emissions' O3 creation potential from its combustion. Variation of the dilution in the different calculations showed evidence for an additional influence of transport effects. Accordingly, further detailed exhaust gas analyses followed by more complex modeling studies are necessary for a proper characterization of the relationship between fuel blend and gasoline combustion products. PMID:12708506
Tight-binding models for ultracold atoms in optical lattices: general formulation and applications
NASA Astrophysics Data System (ADS)
Modugno, Michele; Ibañez-Azpiroz, Julen; Pettini, Giulio
2016-06-01
Tight-binding models for ultracold atoms in optical lattices can be properly defined by using the concept of maximally localized Wannier functions for composite bands. The basic principles of this approach are reviewed here, along with different applications to lattice potentials with two minima per unit cell, in one and two spatial dimensions. Two independent methods for computing the tight-binding coefficients—one ab initio, based on the maximally localized Wannier functions, the other through analytic expressions in terms of the energy spectrum—are considered. In the one dimensional case, where the tight-binding coefficients can be obtained by designing a specific gauge transformation, we consider both the case of quasi resonance between the two lowest bands, and that between s and p orbitals. In the latter case, the role of the Wannier functions in the derivation of an effective Dirac equation is also reviewed. Then, we consider the case of a two dimensional honeycomb potential, with particular emphasis on the Haldane model, its phase diagram, and the breakdown of the Peierls substitution. Tunable honeycomb lattices, characterized by movable Dirac points, are also considered. Finally, general considerations for dealing with the interaction terms are presented.
CFD modeling of turbulent flows around the SSME main injector assembly using porosity formulation
NASA Technical Reports Server (NTRS)
Cheng, Gary C.; Chen, Y. S.; Farmer, Richard C.
1992-01-01
Hot gas turbulent flow distribution around the main injector assembly of the Space Shuttle Main Engine (SSME) and LOX flow distribution through the LOX posts have a great effect on the combustion phenomena inside the main combustion chamber. In order to design a CFD model to be an effective engineering analysis tool with good computational turn-around time (especially for 3-D flow problems) and still maintain good accuracy in describing the flow features, the concept of porosity was employed to describe the effects of blockage and drag force due to the presence of the LOX posts in the turbulent flow field around the main injector assembly of the SSME. Two-dimensional numerical studies were conducted to identify the drag coefficients of the flows, both through tube banks and round the shielded posts, over a wide range of Reynolds numbers. Empirical, analytical expressions of the drag coefficients as a function of local flow Reynolds number were then deduced. The porosity model was applied to the turbulent flow around the main injector assembly of the SSME, and analyses were performed. The 3-D CFD analysis was divided into three parts: LOX dome, hot gas injector assembly, and hydrogen cavity. The numerical results indicate that the mixture ratio at the downstream of injector face was close to stoichiometric around baffle elements.
Moisture Outgassing Rates from TATB-Formulations: Experiments and Kinetic Model Development
Glascoe, E A; Dinh, L N; Small IV, W
2009-07-29
diffusion through pressed parts, or the effects of wet vs. dry machining, or the influence of the synthesis methods in the amount of water present. There are a few different models that have been developed to predict the rate of water release from LX-17 or PBX-9502. These models are, to some extent, limited by the limitations of the experiments. Because all these experiments looked at water release over a relatively short period of time and left the samples relatively undamaged, they serve as a lower bound. In this work, we perform experiments and develop models that can serve as an upper bound on the rate and amount of water that can be released. Our experimental approach is to use temperature programmed desorption (TPD) and monitor the rate and amount of water release as a function of temperature. We analyzed our experimental data using two different kinetic analysis methods (isoconversional analysis and nth-order Arrhenius kinetic fits) and used the results to make predictions. The suitability of these kinetic analysis methods as well as the applicability of these experiments to long term aging (e.g. years) issues are discussed. Using the kinetics from our experiments, we predict the water release at temperature and timescales relevant to the existing literature. Based on our analysis and comparison with older data, the kinetic model(s) developed in this work serve as a relatively accurate (i.e. order of magnitude) method for predicting the water release under a variety of thermal histories.
Sensitivity of modelled sulfate radiative forcing to DMS concentration and air-sea flux formulation
NASA Astrophysics Data System (ADS)
Tesdal, J.-E.; Christian, J. R.; Monahan, A. H.; von Salzen, K.
2015-09-01
In this study, we use an atmospheric general circulation model with explicit aerosol chemistry (CanAM4.1) and several climatologies of surface ocean DMS concentration to assess uncertainties about the climate impact of ocean DMS efflux. Despite substantial variation in the spatial pattern and seasonal evolution of simulated DMS fluxes, the global mean radiative forcing is approximately linearly proportional to the global mean surface flux of DMS; the spatial and temporal distribution of ocean DMS efflux has only a minor effect on the global radiation balance. The effect of the spatial structure, however, generates statistically significant changes in the global mean concentrations of some aerosol species. The effect of seasonality on net radiative forcing is larger than that of spatial distribution, and is significant at global scale.
Formulation, predictions, and sensitivity analysis of a pyrotechnically actuated pin puller model
Gonthier, K.A.; Powers, J.M.
1994-07-01
This article presents an analysis for pyrotechnic combustion and pin motion in the NASA Standard Initiator (NSI) actuated pin puller. The conservation principles and constitutive relations for a multiphase system are posed and reduced to a set of five ordinary differential equations which are solved to predict the system`s performance. The model tracks the interactions of the unreacted, incompressible solid pyrotechnic, incompressible condensed phase combustion products, and gas phase combustion products. Predicted pressure histories for the firing of an NSI into (1) the pin puller device, (2) a 10 cm(sup 3) closed vessel, and (3) an apparatus known as the Dynamic Test Device compare well with experimental results. A sensitivity analysis reveals large regions in parameter space where system performance is insensitive to particular parametric values; smaller regions of high sensitivity are also found. 15 refs.
Gardiner, M.A.; Myers, J.; Hinkebein, T.E.
1990-12-01
The geochemical modeling codes EQ3NR/EQ6 were used to model the interaction of cementitious materials with ground water from the Yucca Mountain proposed nuclear waste repository site in Nevada. This paper presents a preliminary estimate of the compositional changes caused by these interactions in the ground water and in the cement-based compounds proposed for use as sealing and shaft liner materials at the Yucca Mountain site. The geochemical speciation/solubility/reaction path codes EQ3NR/EQ6 were used to model the interaction of cementitious materials and water. Interaction of water with a cementitious material will result in dissolution of certain cement phases and changes in the water chemistry. These changes in the water chemistry may further lead to the precipitation of minerals either in the concrete or in the surrounding tuff at the Yucca Mountain Site (YMS). As part of a larger scoping study, a range of water, cement, and tuff compositions, temperatures, and reaction path modes were used. This paper presents a subset of that study by considering the interaction of three different cement formulations at 25{degree}C with J-13 water using the ``closed`` reaction path mode. This subset was chosen as a base case to answer important questions in selecting the compositions of cementitious materials for use in the proposed repository. 8 refs., 1 fig., 3 tabs.
Laffont, Celine M; Gomeni, Roberto; Zheng, Bo; Heidbreder, Christian; Fudala, Paul J; Nasser, Azmi F
2015-01-01
RBP-7000 is a long-acting formulation of risperidone designed for once-monthly subcutaneous injection for the treatment of schizophrenia. The objective was to estimate clinically effective doses of RBP-7000 based on model simulations and on the comparison with other long-acting injectable antipsychotics. A population pharmacokinetic model of RBP-7000 was developed in 90 clinically stable schizophrenic patients having received single/repeated doses of 60, 90, or 120 mg. Model simulations were conducted to compare active moiety plasma exposure after repeated RBP-7000 administrations to the published data of long-acting risperidone injection (Risperdal® Consta®) at 25 and 50 mg, and of paliperidone palmitate (Invega® Sustenna®) at 50 and 100 mg equivalent paliperidone. Predictions of dopamine D2 receptor occupancy were derived from the simulated active moiety concentrations. Simulations showed similar active moiety plasma exposure at steady-state for 90 mg of RBP-7000 and 25 mg of long-acting risperidone. In comparison to risperidone, RBP-7000 reached effective concentrations immediately after the first administration. RBP-7000 at the doses of 60 and 90 mg provided similar active moiety plasma concentrations at steady-state compared to 50 and 100 mg equivalent paliperidone, respectively. These findings provide guidance for dose selection in Phase III clinical trials and suggest potential benefits for RBP-7000 over competitors. PMID:25043337
NASA Astrophysics Data System (ADS)
Kiani, Keivan
2011-10-01
The potential applications of nanoplates in energy storage, chemical and biological sensors, solar cells, field emission, and transporting of nanocars have been attracted the attentions of the nanotechnology community to them during recent years. Herein, the later application of nanoplates from nonlocal elastodynamic point of view is of interest. To this end, dynamic response of a nanoplate subjected to a moving nanoparticle is examined within the context of nonlocal continuum theory of Eringen. The fully simply supported nanoplate is modeled based on the nonlocal Kirchhoff, Mindlin, and higher-order plate theories. The non-dimensional equations of motion of the nonlocal plate models are established. The effects of moving nanoparticle's weight and existing friction between the surfaces of the moving nanoparticle and nanoplate on the in-plane and out-of-plane vibrations of the nanoplate are incorporated into the formulations of the proposed models. The eigen function expansion and the Laplace transform methods are employed for discretization of the governing equations in the spatial and the time domains, respectively. The analytical expressions of the dynamic deformation field associated with each nonlocal plate theory are obtained when the moving nanoparticle traverses the nanoplate on an arbitrary straight path (an opened path) as well as an ellipse path (a closed path). The dynamic in-plane forces and moments of each nonlocal plate model are also derived. Furthermore, the critical velocity and the critical angular velocity of the moving nanoparticle for the proposed models are expressed analytically for the aforementioned paths. Part II of this work consists in a comprehensive parametric study where the effects of influential parameters on dynamic response of the proposed nonlocal plate models are scrutinized in some detail.
Smith, Kyle K. G.; Poulsen, Jens Aage Nyman, Gunnar; Rossky, Peter J.
2015-06-28
We develop two classes of quasi-classical dynamics that are shown to conserve the initial quantum ensemble when used in combination with the Feynman-Kleinert approximation of the density operator. These dynamics are used to improve the Feynman-Kleinert implementation of the classical Wigner approximation for the evaluation of quantum time correlation functions known as Feynman-Kleinert linearized path-integral. As shown, both classes of dynamics are able to recover the exact classical and high temperature limits of the quantum time correlation function, while a subset is able to recover the exact harmonic limit. A comparison of the approximate quantum time correlation functions obtained from both classes of dynamics is made with the exact results for the challenging model problems of the quartic and double-well potentials. It is found that these dynamics provide a great improvement over the classical Wigner approximation, in which purely classical dynamics are used. In a special case, our first method becomes identical to centroid molecular dynamics.
NASA Astrophysics Data System (ADS)
Riviere, Jim E.; Scoglio, Caterina; Sahneh, Faryad D.; Monteiro-Riviere, Nancy A.
2013-01-01
The field of nanomaterial pharmacokinetics is in its infancy, with major advances largely restricted by a lack of biologically relevant metrics, fundamental differences between particles and small molecules of organic chemicals and drugs relative to biological processes involved in disposition, a scarcity of sufficiently rich and characterized in vivo data and a lack of computational approaches to integrating nanomaterial properties to biological endpoints. A central concept that links nanomaterial properties to biological disposition, in addition to their colloidal properties, is the tendency to form a biocorona which modulates biological interactions including cellular uptake and biodistribution. Pharmacokinetic models must take this crucial process into consideration to accurately predict in vivo disposition, especially when extrapolating from laboratory animals to humans since allometric principles may not be applicable. The dynamics of corona formation, which modulates biological interactions including cellular uptake and biodistribution, is thereby a crucial process involved in the rate and extent of biodisposition. The challenge will be to develop a quantitative metric that characterizes a nanoparticle's surface adsorption forces that are important for predicting biocorona dynamics. These types of integrative quantitative approaches discussed in this paper for the dynamics of corona formation must be developed before realistic engineered nanomaterial risk assessment can be accomplished.
Formulation of the linear model from the nonlinear simulation for the F18 HARV
NASA Technical Reports Server (NTRS)
Hall, Charles E., Jr.
1991-01-01
The F-18 HARV is a modified F-18 Aircraft which is capable of flying in the post-stall regime in order to achieve superagility. The onset of aerodynamic stall, and continued into the post-stall region, is characterized by nonlinearities in the aerodynamic coefficients. These aerodynamic coefficients are not expressed as analytic functions, but rather in the form of tabular data. The nonlinearities in the aerodynamic coefficients yield a nonlinear model of the aircraft's dynamics. Nonlinear system theory has made many advances, but this area is not sufficiently developed to allow its application to this problem, since many of the theorems are existance theorems and that the systems are composed of analytic functions. Thus, the feedback matrices and the state estimators are obtained from linear system theory techniques. It is important, in order to obtain the correct feedback matrices and state estimators, that the linear description of the nonlinear flight dynamics be as accurate as possible. A nonlinear simulation is run under the Advanced Continuous Simulation Language (ACSL). The ACSL simulation uses FORTRAN subroutines to interface to the look-up tables for the aerodynamic data. ACSL has commands to form the linear representation for the system. Other aspects of this investigation are discussed.
Zhou, Ye; Schilling, Oleg; Ghosh, Sanjoy
2002-08-01
The spectral eddy and backscatter viscosity and the spectral eddy and backscatter resistivity for incompressible, three-dimensional, isotropic, nonhelical magnetohydrodynamic (MHD) turbulence are constructed using the eddy-damped quasinormal Markovian statistical closure model developed by Pouquet, Frisch, and Léorat [J. Fluid Mech. 77, 321 (1976)] in terms of primitive variables. The approach used is an extension of the methodology developed by Leslie and Quarini [J. Fluid Mech. 91, 65 (1979)] for fluid turbulence to MHD turbulence. The eddy and backscatter viscosities and the eddy and backscatter resistivities are calculated numerically for assumed kinetic and magnetic energy spectra, E(v)(k) and E(B)(k), with a production subrange and a k(-5/3) inertial subrange for the two cases r(A)=1 and r(A)=1 / 2, where r(A)=E(v)(k)/E(B)(k) is the Alfvén ratio. It is shown that the effects of the unresolved subgrid scales on the resolved-scale velocity and magnetic field consist of an eddy damping and backscatter. The eddy viscosity and resistivity, and the backscatter viscosity and resistivity (the correlation function of the stochastic velocity and magnetic backscatter force) are shown to have a dependence on k/k(c), where k(c) is the cutoff wave number, which is very similar to the dependence calculated in the pure (i.e., nonmagnetic) Navier-Stokes turbulence case. The eddy viscosity and resistivity, and the backscatter viscosity and resistivity numerically calculated here can be used to develop improved subgrid-scale parametrizations for spectral large-eddy simulations of homogenous MHD turbulence. PMID:12241287
Stricker, C.; Fernando, R. L.; Elston, R. C.
1995-01-01
This paper presents an extension of the finite polygenic mixed model of FERNANDO et al. (1994) to linkage analysis. The finite polygenic mixed model, extended for linkage analysis, leads to a likelihood that can be calculated using efficient algorithms developed for oligogenic models. For comparison, linkage analysis of 5 simulated 4021-member pedigrees was performed using the usual mixed model of inheritance, approximated by HASSTEDT (1982), and the finite polygenic mixed model extended for linkage analysis presented here. Maximum likelihood estimates of the finite polygenic mixed model could be inferred to be closer to the simulated values in these pedigrees. PMID:8601502
Juan, Laura W; Zerba, Eduardo N; Mariategui, Pedro; Speicys, Claudio; Tarelli, Guillermo; Demyda, Sebastián; Masuh, Héctor Mario
2010-09-01
A highly viscous formulation containing chlorpyrifos (RET) was evaluated under laboratory, pre-field, and field conditions, and compared against ear tags with organophosphorus insecticides. Laboratory bioassays were performed using Musca domestica L. and a thin layer chromatography (TLC) plate of reversed phase silica gel modeling a lipophilic surface. Insects were exposed to the insecticide vapors of both formulations, directly and indirectly to test for lateral diffusion. Knockdown time 50% (KT(50)) values were determined as toxicological indicators of insecticide release. Minimum KT(50) values of the direct effect of both formulations on horn flies were reached 4 weeks after being applied. The KT(50) effect of migrated insecticides showed that RET formulation had a maximal effectiveness between the fourth and tenth last week. The KT(50) effect of the insecticide migrating from ear tags decreased during the last 2 weeks of the experiment, and the KT(50) effect of the laterally migrated insecticide was significantly higher for the RET formulation during this period. A pre-field bioassay was performed by exposing pieces of rabbit leather with both formulations and recording the KT(50). At the end of the experiment, the KT(50) effect of laterally migrated insecticide was significantly higher for the RET formulation. Regarding vapor emission, as a general trend the KT(50) effect of ear tags was greater than for the RET formulation. To evaluate the horn fly infestation in the field bioassays, photographs of the animal were taken. The results shows that RET provided significant control for 11 weeks while the ear tags provided protection until the 12th week. PMID:20697915
NASA Astrophysics Data System (ADS)
Tripoli, Gregory J.; Smith, Eric A.
2014-06-01
A Variable-Step Topography (VST) surface coordinate system is introduced into a dynamically constrained, scalable, nonhydrostatic atmospheric model for reliable simulations of flows over both smooth and steep terrain without sacrificing dynamical integrity over either type of surface. Backgrounds of both terrain-following and step coordinate model developments are presented before justifying the turn to a VST approach within an appropriately configured host model. In this first part of a two-part sequence of papers, the full formulation of the VST model, prefaced by a description of the framework of its apposite host, i.e., a re-tooled Nonhydrostatic Modeling System (NMS), are presented. [The second part assesses the performance and benefits of the new VST coordinate system in conjunction with seven orthodox obstacle flow problems.] The NMS is a 3-dimensional, nonhydrostatic cloud-mesoscale model, designed for integrations from plume-cloud scales out to regional-global scales. The derivative properties of VST in conjunction with the NMS's newly designed dynamically constrained core are capable of accurately capturing the deformations of flows by any type of terrain variability. Numerical differencing schemes needed to satisfy critical integral constraints, while also effectively enabling the VST lower boundary, are described. The host model constraints include mass, momentum, energy, vorticity and enstrophy conservation. A quasi-compressible closure cast on multiple-nest rotated spherical grids is the underlying framework used to study the advantages of the VST coordinate system. The principle objective behind the VST formulation is to combine the advantages of both terrain-following and step coordinate systems without suffering either of their disadvantages, while at the same time creating a vertical surface coordinate setting suitable for a scalable, nonhydrostatic model, safeguarded with physically realistic dynamical constraints.
Saad, S; Hewett, K; Greenman, J
2012-03-01
An in vitro matrix biofilm perfusion model of tongue-derived microcosms for studying volatile sulfur compound (VSC) biogenesis has been previously described. The model was modified in order to monitor H(2)S in situ by use of a specialized electrode assembly based on microbial fuel cell technology. This system was designed to give real-time measurements expressed as electrode power output, which were proportional to H(2)S levels, measured by other means. In addition to the model modifications, the aim of this study was to demonstrate the biofilm responses following single or multiple exposure to biocidal, biostatic or VSC-inhibiting active compounds used in products. Tongue-derived biofilms (n = 6 per experiment) were perfused with one-fifth strength BHI at 20 ml h(-1) pH 7.2 and pulsed with putative treatment agent, placebo and controls including Zn(2+) ions and chlorhexidine (CHX). Compared with their pre-treatment conditions, all biofilms responded to the treatments in terms of reductions in hydrogen sulfide generation (as detected by the biofilm-electrode response) and other microbial volatile organic compounds (VOCs) as detected using a selected ion flow tube mass spectrometry analyser. The microbiological analysis of the treated and control biofilms show that test products (formulations with active agents) all gave reduced cell populations compared to the control biofilm. An order of effects (magnitude and duration) suggests that both the test agent and CHX produced the strongest reductions, distinct from the responses obtained for the placebo and water controls, which were largely similar. It is concluded that the in vitro perfusion model may be used to replicate many of the activities and reactions believed to be occurring by the tongue biofilm microflora within a real mouth, including H(2)S and VOC biogenesis and their inhibition by exposure to active agents. PMID:22234955
NASA Technical Reports Server (NTRS)
Lee, S. S.; Sengupta, S.
1978-01-01
A mathematical model package for thermal pollution analyses and prediction is presented. These models, intended as user's manuals, are three dimensional and time dependent using the primitive equation approach. Although they have sufficient generality for application at sites with diverse topographical features; they also present specific instructions regarding data preparation for program execution and sample problems. The mathematical formulation of these models is presented including assumptions, approximations, governing equations, boundary and initial conditions, numerical method of solution, and same results.
NASA Astrophysics Data System (ADS)
Carrassi, A.; Weber, R. J. T.; Guemas, V.; Doblas-Reyes, F. J.; Asif, M.; Volpi, D.
2014-04-01
performance is obtained when the stabler component of the model (the ocean) is initialized, but with FFI it is possible to have some predictive skill even when the most unstable compartment (the extratropical atmosphere) is observed. Two advanced formulations, least-square initialization (LSI) and exploring parameter uncertainty (EPU), are introduced. Using LSI the initialization makes use of model statistics to propagate information from observation locations to the entire model domain. Numerical results show that LSI improves the performance of FFI in all the situations when only a portion of the system's state is observed. EPU is an online drift correction method in which the drift caused by the parametric error is estimated using a short-time evolution law and is then removed during the forecast run. Its implementation in conjunction with FFI allows us to improve the prediction skill within the first forecast year. Finally, the application of these results in the context of realistic climate models is discussed.
Technology Transfer Automated Retrieval System (TEKTRAN)
The two source energy balance (TSEB) model calculates the energy balance of the soil–canopy–atmosphere continuum, where turbulent fluxes are based on the Priestley–Taylor equation. The TSEB was revised recently using the Penman–Monteith equation to replace the Priestley–Taylor formulation, thus bett...
NASA Technical Reports Server (NTRS)
Olson, William S.; Bauer, Peter; Viltard, Nicolas F.; Johnson, Daniel E.; Tao, Wei-Kuo
2000-01-01
In this study, a 1-D steady-state microphysical model which describes the vertical distribution of melting precipitation particles is developed. The model is driven by the ice-phase precipitation distributions just above the freezing level at applicable gridpoints of "parent" 3-D cloud-resolving model (CRM) simulations. It extends these simulations by providing the number density and meltwater fraction of each particle in finely separated size categories through the melting layer. The depth of the modeled melting layer is primarily determined by the initial material density of the ice-phase precipitation. The radiative properties of melting precipitation at microwave frequencies are calculated based upon different methods for describing the dielectric properties of mixed phase particles. Particle absorption and scattering efficiencies at the Tropical Rainfall Measuring Mission Microwave Imager frequencies (10.65 to 85.5 GHz) are enhanced greatly for relatively small (approx. 0.1) meltwater fractions. The relatively large number of partially-melted particles just below the freezing level in stratiform regions leads to significant microwave absorption, well-exceeding the absorption by rain at the base of the melting layer. Calculated precipitation backscatter efficiencies at the Precipitation Radar frequency (13.8 GHz) increase in proportion to the particle meltwater fraction, leading to a "bright-band" of enhanced radar reflectivities in agreement with previous studies. The radiative properties of the melting layer are determined by the choice of dielectric models and the initial water contents and material densities of the "seeding" ice-phase precipitation particles. Simulated melting layer profiles based upon snow described by the Fabry-Szyrmer core-shell dielectric model and graupel described by the Maxwell-Garnett water matrix dielectric model lead to reasonable agreement with radar-derived melting layer optical depth distributions. Moreover, control profiles
Lampen, P; Pittermann, W; Heise, H M; Schmitt, M; Jungmann, H; Kietzmann, M
2003-01-01
The skin activation and penetration capability of vitamin E acetate as an ingredient in a basic o/w cream (lamellar type), in liposomes (Rovisome) and microparticles (Roviparts), was investigated under in vitro conditions (BUS model) by the adhesive stripping method. The aim of the study was to compare the analytical results obtained by UV spectroscopy (transmission) and the conventional HPLC method. For the quantitative spectrometric assay, a classical least-squares evaluation of the spectra between 265 and 350 nm, based on the constituent spectra, was used. UV spectroscopy is an economic analytical method for evaluating a large population of samples of the horny layer taken by the adhesive tape stripping method, which is an established tool for depth profiling of substances within the stratum corneum. With regard to the irritation test, no cytotoxicity was recorded for all formulations tested. However, the Roviparts and Rovisome cream formulations induced a considerable activation of the epidermal cells that may contribute to the penetration efficiency of Rovisome-formulated vitamin E acetate. The Rovisome-formulated cream delivered a maximum amount of vitamin E acetate into the horny layer compared to the other formulations tested. The difference can be explained by an alteration of the plasticity of the horny layer inducing a strong reservoir capacity and an activation of upper epidermal cells. Moreover, the opening of the potential pathway for a follicular penetration may be part of the increased reservoir capacity. PMID:12715090
Kadhum, Wesam R; Oshizaka, Takeshi; Ichiro, Hijikuro; Todo, Hiroaki; Sugibayashi, Kenji
2016-06-10
Topical formulations are not always suitable to deliver active ingredients to large areas of skin. Thus, in this study, we aimed to develop an oral formulation for skin tissue targeting with a high bioavailability using liquid crystal (LC) dispersions comprising cubosomes of a mal-absorptive model compound, p-amino benzoic acid (PABA), which is an active element in cosmeceuticals, dietary supplements and skin disorder medicines. The bioavailability and skin concentration of PABA were investigated after oral administration in rats. The effect of the remaining amount of the LC formulation in the stomach on the pharmacokinetic profiles of orally administered PABA was evaluated. The skin permeation and concentration of PABA were also investigated using an in vitro permeation experiment. As a result, the bioavailability of PABA was significantly improved by administration of PABA-LC formulations compared with PABA solution alone, although the effect was greatly influenced by the type of LC-forming lipids. The in vitro skin permeation study showed that the PABA concentration in the skin when applied from the dermis side was higher than when applied from the epidermis side. These findings suggested that oral administration advantageously supports skin targeting, and oral LC formulations could be a promising material in cosmeceutical, dietary and clinical fields. PMID:27072433
Martinez, Marilyn; Mistry, Bipin; Lukacova, Viera; Polli, Jim; Hoag, Stephen; Dowling, Thomas; Kona, Ravikanth; Fahmy, Raafat
2016-07-01
This study explored the utility of mechanistic absorption models to describe the in vivo performance of a low solubility/low permeability compound in normal healthy subjects. Sixteen healthy human volunteers received three oral formulations and an intravenous infusion in a randomized crossover design. Plasma ciprofloxacin concentrations were estimated by HPLC. In vitro ciprofloxacin release from the oral tablets was tested under a variety of conditions. A mechanistic model was used to explore in vivo dissolution and intestinal absorption. Although dissolution rate influenced the location of drug release, absorption challenges appeared to be associated with permeability limitations in the lower small intestine and colon. The apparent relationship between drug solubilization within the upper small intestinal and formulation overall bioavailability suggested the presence of an intestinal absorption window in many individuals. Failure to absorb drug within this window appeared to be linked with the likelihood of in vivo drug precipitation. Challenges encountered during this modeling exercise included large intersubject variability in product in vivo dissolution and the apparent limitations in ciprofloxacin absorption. Although transporter activity was not included as a model parameter, this evaluation demonstrated how identifying the location of drug absorption across several formulations provided an opportunity to identify factors to consider when formulating similar low solubility/low permeability compounds. The use of mechanistic models was invaluable for our understanding of in vivo product performance and for the assessment of individual profiles rather than means. The latter was essential for understanding the potential challenges that may be encountered when introducing a formulation into a patient population. PMID:27116024
NASA Astrophysics Data System (ADS)
Jokulsdottir, Tinna; Archer, David
2016-04-01
We present a new mechanistic model, stochastic, Lagrangian aggregate model of sinking particles (SLAMS) for the biological pump in the ocean, which tracks the evolution of individual particles as they aggregate, disaggregate, sink, and are altered by chemical and biological processes. SLAMS considers the impacts of ballasting by mineral phases, binding of aggregates by transparent exopolymer particles (TEP), zooplankton grazing and the fractal geometry (porosity) of the aggregates. Parameterizations for age-dependent organic carbon (orgC) degradation kinetics, and disaggregation driven by zooplankton grazing and TEP degradation, are motivated by observed particle fluxes and size spectra throughout the water column. The model is able to explain observed variations in orgC export efficiency and rain ratio from the euphotic zone and to the sea floor as driven by sea surface temperature and the primary production rate and seasonality of primary production. The model provides a new mechanistic framework with which to predict future changes on the flux attenuation of orgC in response to climate change forcing.
NASA Astrophysics Data System (ADS)
Wever, Nander; Würzer, Sebastian; Fierz, Charles; Lehning, Michael
2016-04-01
For physics based snow cover models, simulating the formation of dense ice layers inside the snowpack has been a long time challenge. In spite of their small vertical extend, the presence of ice lenses inside the snowpack can have a profound impact on vapor, heat and liquid water flow. These effects may ultimately influence processes on larger scales when, for example, looking at hydrological processes or wet snow avalanche formation. Also microwave emission signals from the snowpack are strongly influenced by the presence of ice layers. Recent laboratory experiments and modelling techniques of liquid water flow in snow have advanced the understanding of liquid water flow in snow, in particular the formation of preferential flow paths. We present a modelling approach in the one-dimensional, multi-layer snow cover model SNOWPACK for preferential flow that is based on a dual-domain approach (i.e., separation into a matrix flow and a preferential flow domain) and solving Richards equation for both. In recently published laboratory experiments, water ponding inside the snowpack has been identified to initiate preferential flow. Those studies also quantified the part of the snowpack involved in preferential flow as a function of grain size. By combining these concepts with an empirical function to determine refreezing of preferential flow water inside the snowpack, we are able to simulate preferential water flow in the model. We found that preferential flow paths arriving at a layer transition in the snowpack may lead to ponding conditions. Subsequent refreezing then may form dense ice layers (>700 kg/m3). We compare the simulations to 14 years of biweekly snow profiles made at the Weissfluhjoch study plot at 2540m altitude in the Eastern Swiss Alps. We show that we are able to reproduce several ice lenses that were observed in the field, whereas some profiles remain challenging to simulate.
NASA Astrophysics Data System (ADS)
Chiang, Po-Chang; Hu, Yiding; Blom, Jason D.; Thompson, David C.
2010-06-01
Inhaled corticosteroids (ICS) are often prescribed as first-line therapy for patients with asthma Despite their efficacy and improved safety profile compared with oral corticosteroids, the potential for systemic side effects continues to cause concern. In order to reduce the potential for systemic side effects, the pharmaceutical industry has begun efforts to generate new drugs with pulmonary-targeted topical efficacy. One of the major challenges of this approach is to differentiate both efficacy and side effects (pulmonary vs. systemic) in a preclinical animal model. In this study, fluticasone and ciclesonide were used as tool compounds to explore the possibility of demonstrating both efficacy and side effects in a rat model using pulmonary delivery via intratracheal (IT) instillation with nanosuspension formulations. The inhibition of neutrophil infiltration into bronchoalveolar lavage fluid (BALF) and cytokine (TNFα) production were utilized to assess pulmonary efficacy, while adrenal and thymus involution as well as plasma corticosterone suppression was measured to assess systemic side effects. Based on neutrophil infiltration and cytokine production data, the ED50s for ciclesonide and fluticasone were calculated to be 0.1 and 0.03 mg, respectively. At the ED50, the average adrenal involution was 7.6 ± 5.3% for ciclesonide versus 16.6 ± 5.1% for fluticasone, while the average thymus involution was 41.0 ± 4.3% for ciclesonide versus 59.5 ± 5.8% for fluticasone. However, the differentiation became less significant when the dose was pushed to the EDmax (0.3 mg for ciclesonide, 0.1 mg for fluticasone). Overall, the efficacy and side effect profiles of the two compounds exhibited differentiation at low to mid doses (0.03-0.1 mg ciclesonide, 0.01-0.03 mg fluticasone), while this differentiation diminished at the maximum efficacious dose (0.3 mg ciclesonide, 0.1 mg fluticasone), likely due to overdosing in this model. We conclude that the rat LPS model using IT
NASA Astrophysics Data System (ADS)
Moritzer, Elmar; Müller, Ellen; Martin, Yannick; Kleeschulte, Rainer
2015-05-01
Today the global market poses great challenges for industrial product development. Complexity, diversity of variants, flexibility and individuality are just some of the features that products have to offer today. In addition, the product series have shorter lifetimes. Because of their high capacity for adaption, polymers are increasingly able to displace traditional materials such as wood, glass and metals from various fields of application. Polymers can only be used to substitute other materials, however, if they are optimally suited to the applications in question. Hence, product-specific material development is becoming increasingly important. Integrating the compounding step in the injection moulding process permits a more efficient and faster development process for a new polymer formulation, making it possible to create new product-specific materials. This process is called inline-compounding on an injection moulding machine. The entire process sequence is supported by software from Bayer Technology called Product Design Workbench (PDWB), which provides assistance in all the individual steps from data management, via analysis and model compilation, right through to the optimization of the formulation and the design of experiments. The software is based on artificial neural networks and can model the formulation-property correlations and thus enable different formulations to be optimized. In the study presented, the workflow and the modelling with the software are presented.
NASA Astrophysics Data System (ADS)
Mahdyiar, M.; Galgana, G.; Shen-Tu, B.; Klein, E.; Pontbriand, C. W.
2014-12-01
Most time dependent rupture probability (TDRP) models are basically designed for a single-mode rupture, i.e. a single characteristic earthquake on a fault. However, most subduction zones rupture in complex patterns that create overlapping earthquakes of different magnitudes. Additionally, the limited historic earthquake data does not provide sufficient information to estimate reliable mean recurrence intervals for earthquakes. This makes it difficult to identify a single characteristic earthquake for TDRP analysis. Physical models based on geodetic data have been successfully used to obtain information on the state of coupling and slip deficit rates for subduction zones. Coupling information provides valuable insight into the complexity of subduction zone rupture processes. In this study we present a TDRP model that is formulated based on subduction zone slip deficit rate distribution. A subduction zone is represented by an integrated network of cells. Each cell ruptures multiple times from numerous earthquakes that have overlapping rupture areas. The rate of rupture for each cell is calculated using a moment balance concept that is calibrated based on historic earthquake data. The information in conjunction with estimates of coseismic slip from past earthquakes is used to formulate time dependent rupture probability models for cells. Earthquakes on the subduction zone and their rupture probabilities are calculated by integrating different combinations of cells. The resulting rupture probability estimates are fully consistent with the state of coupling of the subduction zone and the regional and local earthquake history as the model takes into account the impact of all large (M>7.5) earthquakes on the subduction zone. The granular rupture model as developed in this study allows estimating rupture probabilities for large earthquakes other than just a single characteristic magnitude earthquake. This provides a general framework for formulating physically
Clement, Christian; Capriotti, Joseph A.; Kumar, Manish; Hobden, Jeffery A.; Foster, Timothy P.; Bhattacharjee, Partha S.; Thompson, Hilary W.; Mahmud, Rashed; Liang, Bo
2011-01-01
Purpose. To determine the efficacy of a new formulation of topical dexamethasone 0.1%/povidone-iodine 0.4% (FST-100) in reducing clinical symptoms and infectious viral titers in a rabbit model of adenoviral keratoconjunctivitis. Methods. Rabbit corneas were inoculated bilaterally with 2 × 106 plaque-forming-units (PFU) of adenovirus type 5 (Ad5) after corneal scarification. Animals were randomized 1:1:1:1 (five rabbits per group) to FST-100, 0.5% cidofovir, tobramycin/dexamethasone (Tobradex; Alcon Laboratories, Fort Worth, TX) ophthalmic suspension, and balanced salt solution (BSS; Alcon Laboratories). Treatment began 12 hours after viral inoculation and continued for 7 consecutive days. The eyes were clinically scored daily for scleral inflammation (injection), ocular neovascularization, eyelid inflammation (redness), friability of vasculature, inflammatory discharge (pus), and epiphora (excessive tearing). Eye swabs were collected daily before treatment for the duration of the study. Virus was eluted from the swabs and PFU determined by titration on human A549 cells, according to standard procedures. Results. The FST-100 treatment resulted in significantly lower clinical scores (P < 0.05) than did the other treatments. The 0.5% cidofovir exhibited the most ocular toxicity compared with FST-100, tobramycin/dexamethasone, and balanced salt solution treatments. FST-100 and 0.5% cidofovir significantly (P < 0.05) reduced viral titers compared with tobramycin/dexamethasone or balanced salt solution. Conclusions. FST-100 was the most efficacious in minimizing the clinical symptoms of adenovirus infection in rabbit eyes. FST-100 and 0.5% cidofovir were both equally effective in reducing viral titers and decreasing the duration of viral shedding. By providing symptomatic relief in addition to reducing infectious virus titers, FST-100 should be a valuable addition to treatment of epidemic adenoviral keratoconjunctivitis. PMID:20702820
Vienna, John D.; Kim, Dong-Sang; Skorski, Daniel C.; Matyas, Josef
2013-07-31
Recent glass formulation and melter testing data have suggested that significant increases in waste loading in HLW and LAW glasses are possible over current system planning estimates. The data (although limited in some cases) were evaluated to determine a set of constraints and models that could be used to estimate the maximum loading of specific waste compositions in glass. It is recommended that these models and constraints be used to estimate the likely HLW and LAW glass volumes that would result if the current glass formulation studies are successfully completed. It is recognized that some of the models are preliminary in nature and will change in the coming years. Plus the models do not currently address the prediction uncertainties that would be needed before they could be used in plant operations. The models and constraints are only meant to give an indication of rough glass volumes and are not intended to be used in plant operation or waste form qualification activities. A current research program is in place to develop the data, models, and uncertainty descriptions for that purpose. A fundamental tenet underlying the research reported in this document is to try to be less conservative than previous studies when developing constraints for estimating the glass to be produced by implementing current advanced glass formulation efforts. The less conservative approach documented herein should allow for the estimate of glass masses that may be realized if the current efforts in advanced glass formulations are completed over the coming years and are as successful as early indications suggest they may be. Because of this approach there is an unquantifiable uncertainty in the ultimate glass volume projections due to model prediction uncertainties that has to be considered along with other system uncertainties such as waste compositions and amounts to be immobilized, split factors between LAW and HLW, etc.
NASA Astrophysics Data System (ADS)
Fushiki, Takumi; Yokota, Takayoshi; Kimita, Kazuya; Kumagai, Masatoshi
Probe cars are very effective tools in traffic information gathering. Probe cars can collect the traffic condition data without using roadside sensors but with only using their own equipped sensors. By using probe cars, it is expected that the accuracy of traffic information will be improved and the area coverage of the traffic information service will be increased, and many experimental probe car data collection projects have been implemented. However, the number of probe cars required for adequate information update frequency has not been theoretically discussed. This paper formulates the probabilistic relationships among the traffic volume of probe cars, the area coverage, and the update frequency of traffic information provision. This formulation calculates the adequate number of probe cars to realize traffic information services in advance considering two major service factors: area coverage and update frequency. This paper also validates the theoretical formulation with experimental probe car data collected in a taxi monitoring system.
NASA Technical Reports Server (NTRS)
Lydon, Thomas J.; Fox, Peter A.; Sofia, Sabatino
1993-01-01
We have updated a previous attempt to incorporate within a solar model a treatment of convection based upon numerical simulations of convection rather than mixing-length theory (MLT). We have modified our formulation of convection for a better treatment of the kinetic energy flux. Our solar model has been updated to include a complete range of OPAL opacities, the Debye-Hueckel correction to the equation of state, helium diffusion due to gravitational settling, and atmospheres by Kurucz. We construct a series of models using both MLT and our revised formulation of convection and the compared results to measurements of the solar radius, the solar luminosity, and the depth of the solar convection zone as inferred from helioseismology. We find X(solar) = 0.702 +/- 0.005, Y(solar) = 0.278 +/- 0.005, and Z(solar) = 0.0193 +/- 0.0005.
Knauer, Jens; Krupka, Inke; Fueldner, Christiane; Lehmann, Joerg; Straubinger, Reinhard K.
2011-01-01
Objectives Systemic antibiotic treatment of Lyme borreliosis is effective during the early stages of the infection, while chronic manifestations of the disease may remain refractory and difficult to treat. This study was carried out in order to evaluate the potential of topically applied azithromycin to eliminate the spirochaetal organisms in the skin of the freshly bitten host and thereby prevent Lyme borreliosis. Methods Laboratory mice were challenged with Borrelia burgdorferi sensu stricto by needle inoculation or via infected ticks as vectors. Then, an azithromycin-containing formulation was applied once daily to the sites of exposure for three consecutive days. In the case of needle inoculation, a 5% azithromycin formulation was applied starting 1 h, 3 days and 5 days after infection. In the case of tick exposure, 4%, 10% and 20% azithromycin formulations were applied, starting directly after the detachment of the engorged ticks. Subsequently, the infection status of the mice was determined. Results Concentrations of azithromycin in murine skin were >3800-fold higher than the published minimal inhibitory concentration for B. burgdorferi as soon as 3 h after the first application. After needle inoculation, spirochaetes were not detectable in all infected mice after treatment, if the first application started 1 h or even after 3 days post-infection. Furthermore, no borrelial organisms were detected after topical treatment when ticks were used for spirochaete inoculation. Conclusions Our data indicate that topical treatment with a formulation containing azithromycin is a promising approach to prevent Lyme borreliosis shortly after a tick bite. PMID:21921078
Ohno, Munekazu; Takaki, Tomohiro; Shibuta, Yasushi
2016-01-01
We present the variational formulation of a quantitative phase-field model for isothermal low-speed solidification in a binary dilute alloy with diffusion in the solid. In the present formulation, cross-coupling terms between the phase field and composition field, including the so-called antitrapping current, naturally arise in the time evolution equations. One of the essential ingredients in the present formulation is the utilization of tensor diffusivity instead of scalar diffusivity. In an asymptotic analysis, it is shown that the correct mapping between the present variational model and a free-boundary problem for alloy solidification with an arbitrary value of solid diffusivity is successfully achieved in the thin-interface limit due to the cross-coupling terms and tensor diffusivity. Furthermore, we investigate the numerical performance of the variational model and also its nonvariational versions by carrying out two-dimensional simulations of free dendritic growth. The nonvariational model with tensor diffusivity shows excellent convergence of results with respect to the interface thickness. PMID:26871136
NASA Astrophysics Data System (ADS)
Hari Prasad, K. B. R. R.; Srinivas, C. V.; Satyanarayana, A. N. V.; Naidu, C. V.; Baskaran, R.; Venkatraman, B.
2015-08-01
Season- and stability-dependent turbulence intensity ( σ u / u *, σ v / u *, σ w / u *) relationships are derived from experimental turbulence measurements following surface layer scaling and local stability at the tropical coastal site Kalpakkam, India for atmospheric dispersion parameterization. Turbulence wind components ( u', v', w') measured with fast response UltraSonic Anemometers during an intense observation campaign for wind field modeling called Round Robin Exercise are used to formulate the flux-profile relationships using surface layer similarity theory and Fast Fourier Transform technique. The new relationships (modified Hanna scheme) are incorporated in a Lagrangian Particle Dispersion model FLEXPART-WRF and tested by conducting simulations for a field tracer dispersion experiment at Kalpakkam. Plume dispersion analysis of a ground level hypothetical release indicated that the new turbulent intensity formulations provide slightly higher diffusivity across the plume relative to the original Hanna scheme. The new formulations for σ u , σ v , σ w are found to give better agreement with observed turbulent intensities during both stable and unstable conditions under various seasonal meteorological conditions. The simulated concentrations using the two methods are compared with those obtained from a classical Gaussian model and the observed SF6 concentration. It has been found that the new relationships provide comparatively higher diffusion across the plume relative to the model default Hanna scheme and provide downwind concentration results in better agreement with observations.
NASA Astrophysics Data System (ADS)
Ohno, Munekazu; Takaki, Tomohiro; Shibuta, Yasushi
2016-01-01
We present the variational formulation of a quantitative phase-field model for isothermal low-speed solidification in a binary dilute alloy with diffusion in the solid. In the present formulation, cross-coupling terms between the phase field and composition field, including the so-called antitrapping current, naturally arise in the time evolution equations. One of the essential ingredients in the present formulation is the utilization of tensor diffusivity instead of scalar diffusivity. In an asymptotic analysis, it is shown that the correct mapping between the present variational model and a free-boundary problem for alloy solidification with an arbitrary value of solid diffusivity is successfully achieved in the thin-interface limit due to the cross-coupling terms and tensor diffusivity. Furthermore, we investigate the numerical performance of the variational model and also its nonvariational versions by carrying out two-dimensional simulations of free dendritic growth. The nonvariational model with tensor diffusivity shows excellent convergence of results with respect to the interface thickness.
2011-01-01
Background A warm and humid climate triggers several water-associated diseases such as malaria. Climate- or weather-driven malaria models, therefore, allow for a better understanding of malaria transmission dynamics. The Liverpool Malaria Model (LMM) is a mathematical-biological model of malaria parasite dynamics using daily temperature and precipitation data. In this study, the parameter settings of the LMM are refined and a new mathematical formulation of key processes related to the growth and size of the vector population are developed. Methods One of the most comprehensive studies to date in terms of gathering entomological and parasitological information from the literature was undertaken for the development of a new version of an existing malaria model. The knowledge was needed to allow the justification of new settings of various model parameters and motivated changes of the mathematical formulation of the LMM. Results The first part of the present study developed an improved set of parameter settings and mathematical formulation of the LMM. Important modules of the original LMM version were enhanced in order to achieve a higher biological and physical accuracy. The oviposition as well as the survival of immature mosquitoes were adjusted to field conditions via the application of a fuzzy distribution model. Key model parameters, including the mature age of mosquitoes, the survival probability of adult mosquitoes, the human blood index, the mosquito-to-human (human-to-mosquito) transmission efficiency, the human infectious age, the recovery rate, as well as the gametocyte prevalence, were reassessed by means of entomological and parasitological observations. This paper also revealed that various malaria variables lack information from field studies to be set properly in a malaria modelling approach. Conclusions Due to the multitude of model parameters and the uncertainty involved in the setting of parameters, an extensive literature survey was carried out
Abuhelwa, Ahmad Y; Foster, David J R; Mudge, Stuart; Hayes, David; Upton, Richard N
2015-09-01
Itraconazole is an orally active antifungal agent that has complex and highly variable absorption kinetics that is highly affected by food. This study aimed to develop a population pharmacokinetic model for itraconazole and the active metabolite hydroxyitraconazole, in particular, quantifying the effects of food and formulation on oral absorption. Plasma pharmacokinetic data were collected from seven phase I crossover trials comparing the SUBA-itraconazole and Sporanox formulations of itraconazole. First, a model of single-dose itraconazole data was developed, which was then extended to the multidose data. Covariate effects on itraconazole were then examined before extending the model to describe hydroxyitraconazole. The final itraconazole model was a 2-compartment model with oral absorption described by 4-transit compartments. Multidose kinetics was described by total effective daily dose- and time-dependent changes in clearance and bioavailability. Hydroxyitraconazole was best described by a 1-compartment model with mixed first-order and Michaelis-Menten elimination for the single-dose data and a time-dependent clearance for the multidose data. The relative bioavailability of SUBA-itraconazole compared to that of Sporanox was 173% and was 21% less variable between subjects. Food resulted in a 27% reduction in bioavailability and 58% reduction in the transit absorption rate constant compared to that with the fasted state, irrespective of the formulation. This analysis presents the most extensive population pharmacokinetic model of itraconazole and hydroxyitraconazole in the literature performed in healthy subjects. The presented model can be used for simulating food effects on itraconazole exposure and for performing prestudy power analysis and sample size estimation, which are important aspects of clinical trial design of bioequivalence studies. PMID:26149987
Foster, David J. R.; Mudge, Stuart; Hayes, David
2015-01-01
Itraconazole is an orally active antifungal agent that has complex and highly variable absorption kinetics that is highly affected by food. This study aimed to develop a population pharmacokinetic model for itraconazole and the active metabolite hydroxyitraconazole, in particular, quantifying the effects of food and formulation on oral absorption. Plasma pharmacokinetic data were collected from seven phase I crossover trials comparing the SUBA-itraconazole and Sporanox formulations of itraconazole. First, a model of single-dose itraconazole data was developed, which was then extended to the multidose data. Covariate effects on itraconazole were then examined before extending the model to describe hydroxyitraconazole. The final itraconazole model was a 2-compartment model with oral absorption described by 4-transit compartments. Multidose kinetics was described by total effective daily dose- and time-dependent changes in clearance and bioavailability. Hydroxyitraconazole was best described by a 1-compartment model with mixed first-order and Michaelis-Menten elimination for the single-dose data and a time-dependent clearance for the multidose data. The relative bioavailability of SUBA-itraconazole compared to that of Sporanox was 173% and was 21% less variable between subjects. Food resulted in a 27% reduction in bioavailability and 58% reduction in the transit absorption rate constant compared to that with the fasted state, irrespective of the formulation. This analysis presents the most extensive population pharmacokinetic model of itraconazole and hydroxyitraconazole in the literature performed in healthy subjects. The presented model can be used for simulating food effects on itraconazole exposure and for performing prestudy power analysis and sample size estimation, which are important aspects of clinical trial design of bioequivalence studies. PMID:26149987
NASA Astrophysics Data System (ADS)
Rougé, Charles; Tilmant, Amaury
2015-04-01
Stochastic dual dynamic programming (SDDP) is an optimization algorithm well-suited for the study of large-scale water resources systems comprising reservoirs - and hydropower plants - as well as irrigation nodes. It generates intertemporal allocation policies that balance the present and future marginal value of water while taking into account hydrological uncertainty. It is scalable, in the sense that the time and memory required for computation do not grow exponentially with the number of state variables. Still, this scalability relies on the sampling of a few relevant trajectories for the system, and the approximation of the future value of water through cuts -i.e., hyperplanes - at points along these trajectories. Therefore, the accuracy of this approximation arguably decreases as the number of state variables increases, and it is important not to have more than necessary. In previous formulations, SDDP had three types of state variables, namely storage in each reservoir, inflow at each node and water accumulated during the irrigation season for each crop at each node. We present a simplified formulation for irrigation that does not require using the latter type of state variable. It also requires only two decision variables for each irrigation site, where the previous formulation had four per crop - and there may be several crops at the same site. This reduction in decision variables effectively reduces computation time, since SDDP decomposes the stochastic, multiperiodic, non-linear maximization problem into a series of linear ones. The proposed formulation, while computationally simpler, is mathematically equivalent to the previous one, and therefore the model gives the same results. A corollary of this formulation is that marginal utility of water at an irrigation site is effectively related to consumption at that site, through a piecewise linear function representing the net benefits from irrigation. Last but not least, the proposed formulation can be
Subhasree, N.; Kamella, Ananthkumar; Kaliappan, Ilango; Agrawal, Aruna; Dubey, Govind Prasad
2015-01-01
Objective: To investigate the antidiabetic and antihyperlipidemic activities of polyherbal formulation (PHF) containing hydroalcoholic extracts of four plants namely Salacia oblonga, Salacia roxbhurgii, Garcinia indica and Lagerstroemia parviflora in streptozotocin (STZ)-induced diabetic rats by administering oral doses (200 and 400 mg/kg body weight). Materials and Methods: Animals were divided into diabetic and nondiabetic groups. Rats were fed with a high-fat diet (HFD) and induced with a single low dose of STZ (35 mg/kg) i.p. Diabetic rats were treated with formulation (200 and 400 mg/kg) and metformin 250 mg/kg. Blood glucose levels were measured using blood glucose test strips with ACCU CHEK glucometer. Lipid profile and gluconeogenic enzymes were determined in normal and STZ-induced diabetic rats after oral administration of the PHF for 28 days. Histopathological changes in diabetic rat organs (pancreas, liver, and kidney) were also observed after PHF treatment. Results: Treatment of diabetic rats with PHF and metformin decreased plasma glucose and lipid profile levels. Blood glucose level showed significant reduction after 28 days of treatment with formulation at 200 and 400 mg/kg and in metformin. Formulation treated rats showed significant (P < 0.001) decrease in the activities of gluconeogenic enzymes. Histological examination of various organ tissues of normal control, diabetic control, and drug-treated rats revealed significant results. Treatment with PHF reverses the most blood and tissue changes toward the normal level. Conclusion: These findings suggested the antihyperglycemic and antihyperlipidemic properties of the PHF and thus help in preventing future complications of diabetes. PMID:26600639
Kumar, K; Rai, A K
2012-10-01
Curcumin, the active ingredient of the spice turmeric, has a long history as an herbal remedy for a variety of diseases. Transdermal drug delivery has been recognized as an alternative route to oral delivery. Proniosomes offer a versatile vesicle delivery concept with the potential for drug delivery via the transdermal route. In this study, different proniosomal gel bases were prepared by the ether injection method, using Span 60 and Span 80, Tween 20, cholesterol, and formulation PA2. They were characterized by scanning electron microscopy, revealing vesicular structures, and assessed for stability and effect on in vitro skin permeation using rat skin. Anti-inflammatory and anti-arthritic effects of formulation PA2 and PB1 were compared with a standard market product containing indomethacin. The effect of formulation PA2 and PB1 was evaluated for acute inflammation in carrageenan induced rat paw edema and for chronic inflammation in complete Freud's adjuvant (CFA) induced arthritis in rats. Further histopathological and radiographic evaluation was performed. The investigated curcumin loaded proniosomal formula proved to be non-irritant, non-toxic, but had lower anti-inflammatory and anti-arthritic effects than the marketed indomethacin products. PMID:23136720
Takada, Shigeyuki; Kurokawa, Tomofumi; Misaki, Masafumi; Taira, Keiko; Yamagata, Yutaka
2003-07-01
A new animal model to evaluate the long-term growth rate produced by a sustained-release formulation of recombinant human growth hormone (rhGH) over one month was developed and the usefulness of our microcapsule formulations was demonstrated in this model. Long-term pharmacological effects by subcutaneous injection of microcapsules for sustained release of rhGH were evaluated in hypophysectomized (Hpx) rats treated with immunosuppressive agent along with hormone supplement. Copoly(DL-lactic/glycolic)acid (PLGA) microcapsules for sustained release of rhGH, a two-week sustained-release formulation (rhGH-SR-2W) and a one-month sustained-release formulation (rhGH-SR-1M), were prepared by a solid-in-oil-in-water emulsion solvent evaporation technique. Body-weight gain, body-length gain and serum levels of rat insulin-like growth factor-I (rIGF-I) induced by subcutaneous injection of rhGH-SR were compared with those by daily injections of rhGH solution in Hpx rats for 35 days. Serum IGF-I levels in Hpx rats after the injection of rhGH-SR2W microcapsules were higher than those after daily injections of rhGH solution. Body-length gain, a new parameter, after single injection of rhGH-SR-1M microcapsules demonstrated the higher growth rate than that after daily injections of rhGH solution for 35 days. Thus, single injection of rhGH-SR microcapsules demonstrated long-term pharmacological effects greater than those by daily injections of rhGH solution in a newly developed model, immunosuppressed Hpx rats. PMID:12906752
NASA Astrophysics Data System (ADS)
Degrande, G.; Clouteau, D.; Othman, R.; Arnst, M.; Chebli, H.; Klein, R.; Chatterjee, P.; Janssens, B.
2006-06-01
A numerical model is presented to predict vibrations in the free field from excitation due to metro trains in tunnels. The three-dimensional dynamic tunnel-soil interaction problem is solved with a subdomain formulation, using a finite element formulation for the tunnel and a boundary element method for the soil. The periodicity of the geometry in the longitudinal direction of the tunnel is exploited using the Floquet transform, limiting the discretization to a single-bounded reference cell. The responses of two different types of tunnel due to a harmonic load on the tunnel invert are compared, both in the frequency-wavenumber and spatial domains. The first tunnel is a shallow cut-and-cover masonry tunnel on the Paris metro network, embedded in layers of sand, while the second tunnel is a deep bored tunnel of London Underground, with a cast iron lining and embedded in the London clay.
Mason, Laura M; Chessa, Simona; Huatan, Hiep; Storey, David E; Gupta, Pranav; Burley, Jonathan; Melia, Colin D
2016-08-20
The Dynamic Gastric Model (DGM) is an in-vitro system which aims to closely replicate the complex mixing, dynamic biochemical release and emptying patterns of the human stomach. In this study, the DGM was used to understand how the polymer content of hydrophilic matrices influences drug release in fasted and fed dissolution environments. Matrices containing a soluble model drug (caffeine) and between 10 and 30% HPMC 2208 (METHOCEL(®) K4M CR) were studied in the DGM under simulated fasted and fed conditions. The results were compared with compendial USP I and USP II dissolution tests. The USP I and II tests clearly discriminated between formulations containing different polymer levels, whereas the fasted DGM test bracketed drug release profiles into three groups and was not able to distinguish between some different formulations. DGM tests in the fed state showed that drug release was substantially influenced by the presence of a high fat meal. Under these conditions, there was a delay before initial drug release, and differences between matrices with different polymer contents were no longer clear. Matrices containing the typical amount of HPMC polymer (30% w/w) exhibited similar release rates under fed and fasted DGM conditions, but matrices with lower polymer contents exhibited more rapid drug release in the fasted state. In both the fasted and fed states erosion mechanisms appeared to dominate drug release in the DGM: most likely a consequence of the changing, cylindrical forces exerted during simulated antral cycling. This is in contrast to the USP tests in which diffusion played a significant role in the drug release process. This study is one of the first publications where a series of extended release (ER) formulations have been studied in the DGM. The technique appears to offer a useful tool to explore the potential sensitivity of ER formulations with respect to the gastric environment, especially the presence of food. PMID:27311354
Ghrayeb, Shadi Z.; Ougouag, Abderrafi M.; Ouisloumen, Mohamed; Ivanov, Kostadin N.
2014-01-01
A multi-group formulation for the exact neutron elastic scattering kernel is developed. It incorporates the neutron up-scattering effects, stemming from lattice atoms thermal motion and accounts for it within the resulting effective nuclear cross-section data. The effects pertain essentially to resonant scattering off of heavy nuclei. The formulation, implemented into a standalone code, produces effective nuclear scattering data that are then supplied directly into the DRAGON lattice physics code where the effects on Doppler Reactivity and neutron flux are demonstrated. The correct accounting for the crystal lattice effects influences the estimated values for the probability of neutron absorption and scattering, which in turn affect the estimation of core reactivity and burnup characteristics. The results show an increase in values of Doppler temperature feedback coefficients up to -10% for UOX and MOX LWR fuels compared to the corresponding values derived using the traditional asymptotic elastic scattering kernel. This paper also summarizes the results done on this topic to date.
Smith, Maree T; Wyse, Bruce D; Edwards, Stephen R; El-Tamimy, Mahmoud; Gaetano, Giacinto; Gavin, Paul
2015-07-01
This study was designed to assess the analgesic efficacy and systemic exposure of oxycodone administered topically in a novel tocopheryl phosphate mixture (TPM) gel formulation, to the inflamed hindpaws in a rat model of inflammatory pain. Unilateral hindpaw inflammation was induced in male Sprague-Dawley rats by intraplantar (i.pl.) injection of Freund's complete adjuvant (FCA). Mechanical hyperalgesia and hindpaw inflammation were assessed by measuring paw pressure thresholds and hindpaw volume, respectively, just prior to i.pl. FCA and again 5-6 days later. The analgesic effects of oxycodone administered topically (1 mg in TPM gel) or by i.pl. injection (50 μg), were assessed. Systemic oxycodone exposure was assessed over an 8-h postdosing interval following topical application. Skin permeation of oxycodone from the gel formulation was assessed in vitro using Franz diffusion cells. Oxycodone administered topically or by i.pl. injection produced significant (p < 0.05) analgesia in the inflamed hindpaws. Systemic oxycodone exposure was insignificant after topical dosing. The in vitro cumulative skin permeation of oxycodone was linearly related to the amount applied. Topical TPM/oxycodone gel formulations have the potential to alleviate moderate to severe inflammatory pain conditions with minimal systemic exposure, thereby avoiding central nervous system (CNS)-mediated adverse effects associated with oral administration of opioid analgesics. PMID:25995048
NASA Technical Reports Server (NTRS)
Lee, C. H.
1978-01-01
A 3-D finite element program capable of simulating the dynamic behavior in the vicinity of the impact point, together with predicting the dynamic response in the remaining part of the structural component subjected to high velocity impact is discussed. The finite algorithm is formulated in a general moving coordinate system. In the vicinity of the impact point contained by a moving failure front, the relative velocity of the coordinate system will approach the material particle velocity. The dynamic behavior inside the region is described by Eulerian formulation based on a hydroelasto-viscoplastic model. The failure front which can be regarded as the boundary of the impact zone is described by a transition layer. The layer changes the representation from the Eulerian mode to the Lagrangian mode outside the failure front by varying the relative velocity of the coordinate system to zero. The dynamic response in the remaining part of the structure described by the Lagrangian formulation is treated using advanced structural analysis. An interfacing algorithm for coupling CELFE with NASTRAN is constructed to provide computational capabilities for large structures.
Chapman, B; Scurrah, K J; Ross, T
2010-05-01
A survey of 12 Australian manufacturers indicated that mild-tasting acids and preservatives are used to partially replace acetic acid in cold-filled acid dressings and sauces. In contrast to traditional ambient temperature distribution practices, some manufacturers indicated that they supply the food service sector with cold-filled acid products prechilled for incorporation into ready-to-eat foods. The Comité des Industries des Mayonnaises et Sauces Condimentaires de la Communauté Economique Européenne (CIMSCEE) Code, a formulation guideline used by the industry to predict the safety of cold-filled acid formulations with respect to Salmonella enterica and Escherichia coli, does not extend to the use of acids and preservatives other than acetic acid nor does it consider the effects of chill distribution. We found insufficient data in the published literature to comprehensively model the response of S. enterica and E. coli to all of the predictor variables (i.e., pH, acetic acid, NaCl, sugars, other acids, preservatives, and storage temperature) of relevance for contemporary cold-filled acid products in Australia. In particular, we noted a lack of inactivation data for S. enterica at aqueous-phase NaCl concentrations of >3% (wt/wt). However, our simple models clearly identified pH and 1/absolute temperature of storage as the most important variables generally determining inactivation. To develop robust models to predict the effect of contemporary formulation and storage variables on product safety, additional empirical data are required. Until such models are available, our results support challenge testing of cold-filled acid products to ascertain their safety, as suggested by the CIMSCEE, but suggest consideration of challenging with both E. coli and S. enterica at incubation temperatures relevant to intended product distribution temperatures. PMID:20501041
Minier, Jean-Pierre; Chibbaro, Sergio; Pope, Stephen B.
2014-11-15
In this paper, we establish a set of criteria which are applied to discuss various formulations under which Lagrangian stochastic models can be found. These models are used for the simulation of fluid particles in single-phase turbulence as well as for the fluid seen by discrete particles in dispersed turbulent two-phase flows. The purpose of the present work is to provide guidelines, useful for experts and non-experts alike, which are shown to be helpful to clarify issues related to the form of Lagrangian stochastic models. A central issue is to put forward reliable requirements which must be met by Lagrangian stochastic models and a new element brought by the present analysis is to address the single- and two-phase flow situations from a unified point of view. For that purpose, we consider first the single-phase flow case and check whether models are fully consistent with the structure of the Reynolds-stress models. In the two-phase flow situation, coming up with clear-cut criteria is more difficult and the present choice is to require that the single-phase situation be well-retrieved in the fluid-limit case, elementary predictive abilities be respected and that some simple statistical features of homogeneous fluid turbulence be correctly reproduced. This analysis does not address the question of the relative predictive capacities of different models but concentrates on their formulation since advantages and disadvantages of different formulations are not always clear. Indeed, hidden in the changes from one structure to another are some possible pitfalls which can lead to flaws in the construction of practical models and to physically unsound numerical calculations. A first interest of the present approach is illustrated by considering some models proposed in the literature and by showing that these criteria help to assess whether these Lagrangian stochastic models can be regarded as acceptable descriptions. A second interest is to indicate how future
Ahmad, Ajaz; Mondal, Sujan Kumar; Mukhopadhyay, Debabrata; Banerjee, Rajkumar; Alkharfy, Khalid M
2016-03-01
The objective of the present study is to develop a liposomal formulation for delivering anticancer drug to breast cancer stem-cell-like cells, ANV-1, and evaluate its pharmacokinetics in an animal model. The anticancer drug ESC8 was used in dexamethasone (Dex)-associated liposome (DX) to form ESC8-entrapped liposome named DXE. ANV-1 cells showed high-level expression of NRP-1. To enhance tumor regression, we additionally adapted to codeliver the NRP-1 shRNA-encoded plasmid using the established DXE liposome. In vivo efficacy of DXE-NRP-1 was carried out in mice bearing ANV-1 cells as xenograft tumors and the extent of tumor growth inhibition was evaluated by tumor-size measurement. A significant difference in tumor volume started to reveal between DXE-NRP-1 group and DXE-Control group. DXE-NRP-1 group showed ∼4 folds and ∼2.5 folds smaller tumor volume than exhibited by untreated and DXE-Control-treated groups, respectively. DXE disposition was evaluated in Sprague-Dawley rats following an intraperitoneal dose (3.67 mg/kg of ESC8 in DXE). The plasma concentrations of ESC8 in the DXE formulation were measured by liquid chromatography mass spectrometry and pharmacokinetic parameters were determined using a noncompartmental analysis. ESC8 had a half-life of 11.01 ± 0.29 h, clearance of 2.10 ± 3.63 L/kg/h, and volume of distribution of 33.42 ± 0.83 L/kg. This suggests that the DXE liposome formulation could be administered once or twice daily for therapeutic efficacy. In overall, we developed a potent liposomal formulation with favorable pharmacokinetic and tumor regressing profile that could sensitize and kill highly aggressive and drug-resistive cancer stem-cell-like cells. PMID:26832839
Webb, S.W.
1996-05-01
Two models for gas-phase diffusion and advection in porous media, the Advective-Dispersive Model (ADM) and the Dusty-Gas Model (DGM), are reviewed. The ADM, which is more widely used, is based on a linear addition of advection calculated by Darcy`s Law and ordinary diffusion using Fick`s Law. Knudsen diffusion is often included through the use of a Klinkenberg factor for advection, while the effect of a porous medium on the diffusion process is through a porosity-tortuosity-gas saturation multiplier. Another, more comprehensive approach for gas-phase transport in porous media has been formulated by Evans and Mason, and is referred to as the Dusty- Gas Model (DGM). This model applies the kinetic theory of gases to the gaseous components and the porous media (or ``dust``) to develop an approach for combined transport due to ordinary and Knudsen diffusion and advection including porous medium effects. While these two models both consider advection and diffusion, the formulations are considerably different, especially for ordinary diffusion. The various components of flow (advection and diffusion) are compared for both models. Results from these two models are compared to isothermal experimental data for He-Ar gas diffusion in a low-permeability graphite. Air-water vapor comparisons have also been performed, although data are not available, for the low-permeability graphite system used for the helium-argon data. Radial and linear air-water heat pipes involving heat, advection, capillary transport, and diffusion under nonisothermal conditions have also been considered.
NASA Astrophysics Data System (ADS)
Kleidon, Axel
2016-04-01
derive the expected behavior of the Earth system and its response to change from first principles. This approach can provide a few key insights on essential components for model building that appear to be rather general. This starts with a thermodynamic formulation of processes in terms of the energy that these convert as this sets the basis for formulating fundamental limits. Interactions then play a central role in shaping these limits as well as the formulation of the system boundary. In addition to providing insights into model building, the approach can provide a baseline reference for setting up hypotheses that can supplement the interpretation of observations and numerical simulations with comprehensive Earth system models.
NASA Astrophysics Data System (ADS)
Alexandratou, E.; Kyriazi, M.; Trebst, T.; Gräfe, S.; Yova, D.
2007-07-01
Photodynamic therapy (PDT) has been used in the treatment of various skin diseases including non melanoma skin carcinomas (NMSC). However, until now there are no publications concerning the efficacy of PDT after topical application of mTHPC. Although topical photosensitizer application presents many advantages over systemic drug administration, ALA-induced protoporphyrin IX is the only sensitizer topically used so far. In the present study photodynamic efficacy of the highly potent sensitizer meso-tetra(hydroxyphenyl)chlorin (mTHPC), supplied in a novel liposome formulation is investigated after topical application in hairless SKH-HR1 mice, bearing non melanoma skin carcinomas. The drug was applied topically for drug - light interval of 4 hours. The fluence rates were 100 and 50 mW/cm2 and two total energy doses, 10 J/cm2 and 100 J/cm2 were studied in groups of 5 animals. Three PDT sessions were performed in each animal, once every 7 days. The final evaluation of PDT effects was performed 14 days after the 3rd PDT treatment by measuring the geometrical characteristics of tumors. The groups treated with 100 mW/cm2 presented a higher complete tumor remission than the group of 50 mW/cm2 but an unusual high mortality. In the group of 50 mW/cm2 and 100 J/cm2, although the complete tumor remission percentage is poor, the tumor growth rate was decreased. No lesion, papilloma, or tumor was observed in the treated area even six months after tumor remission. Furthermore tumours up to 7 mm were achieved to be treated, indicating that this novel mTHPC formulation could be used for deeper and not only superficial carcinomas or lesions.
Holm, René; Olesen, Niels Erik; Alexandersen, Signe Dalgaard; Dahlgaard, Birgitte N; Westh, Peter; Mu, Huiling
2016-05-25
Preservatives are inactivated when added to conserve aqueous cyclodextrin (CD) formulations due to complex formation between CDs and the preservative. To maintain the desired conservation effect the preservative needs to be added in apparent surplus to account for this inactivation. The purpose of the present work was to establish a mathematical model, which defines this surplus based upon knowledge of stability constants and the minimal concentration of preservation to inhibit bacterial growth. The stability constants of benzoic acid, methyl- and propyl-paraben with different frequently used βCDs were determined by isothermal titration calorimetry. Based upon this knowledge mathematical models were constructed to account for the equilibrium systems and to calculate the required concentration of the preservations, which was evaluated experimentally based upon the USP/Ph. Eur./JP monograph. The mathematical calculations were able to predict the needed concentration of preservation in the presence of CDs; it clearly demonstrated the usefulness of including all underlying chemical equilibria in a mathematical model, such that the formulation design can be based on quantitative arguments. PMID:26391874
Feed Formulation and Manufacture
Technology Transfer Automated Retrieval System (TEKTRAN)
This chapter provides information on feed formulation and manufacture. To formulate and manufacture high quality fish feeds, including tilapia feeds, one should have knowledge of nutrient requirements, nutrient composition, digestibility, and availability of feed ingredients; impacts of manufacturin...
NASA Technical Reports Server (NTRS)
Georgiadis, Nicholas J.; Chitsomboon, Tawit; Zhu, Jiang
1994-01-01
This report documents the changes that were made to the two-equation k-epsilon turbulence model in the NPARC (National-PARC) code. The previous model based on the low Reynolds number model of Speziale, was replaced with the low Reynolds number k-epsilon model of Chien. The most significant difference was in the turbulent Prandtl numbers appearing in the diffusion terms of the k and epsilon transport equations. A new inflow boundary condition and stability enhancements were also implemented into the turbulence model within NPARC. The report provides the rationale for making the change to the Chien model, code modifications required, and comparisons of the performances of the new model with the previous k-epsilon model and algebraic models used most often in PARC/NPARC. The comparisons show that the Chien k-epsilon model installed here improves the capability of NPARC to calculate turbulent flows.
NASA Astrophysics Data System (ADS)
Cammalleri, C.; Anderson, M. C.; Ciraolo, G.; Durso, G.; Kustas, W. P.; La Loggia, G.; Minacapilli, M.
2010-12-01
For open orchard and vineyard canopies containing significant fractions of exposed soil (>50%), typical of Mediterranean agricultural regions, the energy balance of the vegetation elements is strongly influenced by heat exchange with the bare soil/substrate. For these agricultural systems a "two-source" approach, where radiation and turbulent exchange between the soil and canopy elements are explicitly modelled, appears to be the only suitable methodology for reliably assessing energy fluxes. In strongly clumped canopies, the effective wind speed profile inside and below the canopy layer can strongly influence the partitioning of energy fluxes between the soil and vegetation components. To assess the impact of in-canopy wind profile on model flux estimates, an analysis of three different formulations is presented, including algorithms from Goudriaan (1977), Massman (1987) and Lalic et al. (2003). The in-canopy wind profile formulations are applied to the thermal-based two-source energy balance (TSEB) model developed by Norman et al. (1995) and modified by Kustas and Norman (1999). High resolution airborne remote sensing images, collected over an agricultural area located in the western part of Sicily (Italy) comprised primarily of vineyards, olive and citrus orchards, are used to derive all the input parameters needed to apply the TSEB. The images were acquired from June to October 2008 and include a relatively wide range of meteorological and soil moisture conditions. A preliminary sensitivity analysis of the three wind profile algorithms highlights the dependence of wind speed just above the soil/substrate to leaf area index and canopy height over the typical range of canopy properties encountered in these agricultural areas. It is found that differences among the models in wind just above the soil surface are most significant under sparse and medium fractional cover conditions (15-50%). The TSEB model heat flux estimates are compared with micro
NASA Astrophysics Data System (ADS)
Yang, J.; Abubakar, A.
2012-12-01
The ability to accurately and efficiently simulate elastic wave scattering processes is very important in geophysical prospecting applications. A recently proposed formulation of an integral equation for solving three-dimensional elastic wave scattering problems is numerically implemented. The approach is formulated in terms of the stress tensor and particle velocity vector, where the symmetric tensors of rank two are decomposed into their omnidirectional and deviatoric constituents. Subsequently, this integral equation is used to obtain a contrast-source type integral equation. For solving these integral equations we employ a Conjugate Gradient Fast Fourier Transform (CG-FFT) scheme, which is based on quadrature formulas that provide (second-order) accurate approximations while retaining the convolution nature of the relevant integrals that make them amenable to efficient evaluation via Fast Fourier Transforms. As linear solvers we employ the Conjugate Gradient for Normal Residual (CGNR) scheme, which is always monotonically convergent, but has a slow convergent rate, and the Bi-Conjugate Gradient Stabilized (BiCGSTAB) scheme, which is more efficient, but it is less stable. The convergence rates of iterative schemes are further improved through the use of a simple diagonal preconditioner. We show a number of numerical results that demonstrate the accuracy and efficiency of the implemented 3D elastic modeling approach. Numerical models include both simple synthetic models and classic seismic test models (such as the SEG/EAGE salt model and the Marmousi2 model). Excellent benchmark results against a Finite Difference Time Domain (FDTD) algorithm are also presented. These features suggest that the present numerical scheme may provide the basis for the so-called contrast-source inversion method.
Olivares-Morales, Andrés; Kamiyama, Yoshiteru; Darwich, Adam S; Aarons, Leon; Rostami-Hodjegan, Amin
2015-01-25
Controlled release (CR) formulations are usually designed to achieve similar exposure (AUC) levels as the marketed immediate release (IR) formulation. However, the AUC is often lower following CR compared to IR formulations. There are a few exceptions when the CR formulations have shown higher AUC. This study investigated the impact of CR formulations on oral drug absorption and CYP3A4-mediated gut wall metabolism. A review of the current literature on relative bioavailability (Frel) between CR and IR formulations of CYP3A substrates was conducted. This was followed by a systematic analysis to assess the impact of the release characteristics and the drug-specific factors (including metabolism and permeability) on oral bioavailability employing a physiologically-based pharmacokinetic (PBPK) modelling and simulation approach. From the literature review, only three CYP3A4 substrates showed higher Frel when formulated as CR. Several scenarios were investigated using the PBPK approach; in most of them, the oral absorption of CR formulations was lower as compared to the IR formulations. However, for highly permeable compounds that were CYP3A4 substrates the reduction in absorption was compensated by an increase in the fraction that escapes from first pass metabolism in the gut wall (FG), where the magnitude was dependent on CYP3A4 affinity. The systematic simulations of various interplays between different parameters demonstrated that BCS class 1 highly-cleared CYP3A4 substrates can display up to 220% higher relative bioavailability when formulated as CR compared to IR, in agreement with the observed data collected from the literature. The results and methodology of this study can be employed during the formulation development process in order to optimize drug absorption, especially for CYP3A4 substrates. PMID:25444842
NASA Astrophysics Data System (ADS)
Oberai, Assad A.; Hughes, Thomas J. R.
2016-04-01
We explore a general family of eddy viscosity models for the large-eddy simulation of turbulence within the framework of the Variational Multiscale Method. Our investigation encompasses various fine-scale eddy viscosities and coarse-scale residual-based constructs. We delineate the domain of parameter space in which physically and mathematically suitable models exist, and identify several sub-families of potentially useful models that are either entirely new or extend previously proposed ones. We also combine classical modeling ideas, that lead to turbulent kinetic energy evolution equations, with the residual-based approach to derive a new residual-driven, one-equation dynamic model.
NASA Technical Reports Server (NTRS)
Sud, Y. C.; Smith, W. E.
1984-01-01
The influence of some modifications to the parameters of the current general circulation model (GCM) is investigated. The aim of the modifications was to eliminate strong occasional bursts of oscillations in planetary boundary layer (PBL) fluxes. Smoothly varying bulk aerodynamic friction and heat transport coefficients were found by ensemble averaging of the PBL fluxes in the current GCM. A comparison was performed of the simulations of the modified model and the unmodified model. The comparison showed that the surface fluxes and cloudiness in the modified model simulations were much more accurate. The planetary albedo in the model was also realistic. Weaknesses persisted in the models positioning of the Inter-tropical convergence zone (ICTZ) and in the temperature estimates for polar regions. A second simulation of the model following reparametrization of the cloud data showed improved results and these are described in detail.
Mazzotti, M.; Bartoli, I.; Marzani, A.; Viola, E.
2013-09-01
Highlights: •Dispersive properties of viscoelastic waveguides and cavities are computed using a regularized 2.5D BEM. •Linear viscoelasticity is introduced at the constitutive level by means of frequency dependent complex moduli. •A contour integral algorithm is used to solve the nonlinear eigenvalue problem. •The Sommerfeld radiation condition is used to select the permissible Riemann sheets. •Attenuation of surface waves in cavities approaches the attenuation of Rayleigh waves. -- Abstract: A regularized 2.5D boundary element method (BEM) is proposed to predict the dispersion properties of damped stress guided waves in waveguides and cavities of arbitrary cross-section. The wave attenuation, induced by material damping, is introduced using linear viscoelastic constitutive relations and described in a spatial manner by the imaginary component of the axial wavenumber. The discretized dispersive wave equation results in a nonlinear eigenvalue problem, which is solved obtaining complex axial wavenumbers for a fixed frequency using a contour integral algorithm. Due to the singular characteristics and the multivalued feature of the wave equation, the requirement of holomorphicity inside the contour region over the complex wavenumber plane is fulfilled by the introduction of the Sommerfeld branch cuts and by the choice of the permissible Riemann sheets. A post processing analysis is developed for the extraction of the energy velocity of propagative guided waves. The reliability of the method is demonstrated by comparing the results obtained for a rail and a bar with square cross-section with those obtained from a 2.5D Finite Element formulation also known in literature as Semi Analytical Finite Element (SAFE) method. Next, to show the potential of the proposed numerical framework, dispersion properties are predicted for surface waves propagating along cylindrical cavities of arbitrary cross-section. It is demonstrated that the attenuation of surface waves
NASA Astrophysics Data System (ADS)
Casamitjana, Xavier; Pujol, Dolors; Colomer, Jordi; Serra, Teresa
2012-02-01
Oscillating-grid turbulence (OGT) in a homogeneous fluid has been widely investigated. In a recent paper Pujol et al. (2010) used an oscillating grid to mimic wind-generated turbulence. They quantified the vertical distribution of turbulent kinetic energy (TKE) above and within different types of vegetation, which were simulated by constructing two different canopies at the bottom of a water tank. The first canopy, made of PVC cylinders, was rigid and the second, made of nylon threads, was semi-rigid. We propose a k- ɛ turbulence model to simulate the results obtained in their paper. Two source terms (˜(TKE) 3/2) were added to a classical k- ɛ turbulence formulation to account for canopy dissipation. Results of the model show good agreement with experimental data.
Franek, F; Jarlfors, A; Larsen, F; Holm, P; Steffansen, B
2015-09-18
Desvenlafaxine is a biopharmaceutics classification system (BCS) class 1 (high solubility, high permeability) and biopharmaceutical drug disposition classification system (BDDCS) class 3, (high solubility, poor metabolism; implying low permeability) compound. Thus the rate-limiting step for desvenlafaxine absorption (i.e. intestinal dissolution or permeation) is not fully clarified. The aim of this study was to investigate whether dissolution and/or intestinal permeability rate-limit desvenlafaxine absorption from an immediate-release formulation (IRF) and Pristiq(®), an extended release formulation (ERF). Semi-mechanistic models of desvenlafaxine were built (using SimCyp(®)) by combining in vitro data on dissolution and permeation (mechanistic part of model) with clinical data (obtained from literature) on distribution and clearance (non-mechanistic part of model). The model predictions of desvenlafaxine pharmacokinetics after IRF and ERF administration were compared with published clinical data from 14 trials. Desvenlafaxine in vivo dissolution from the IRF and ERF was predicted from in vitro solubility studies and biorelevant dissolution studies (using the USP3 dissolution apparatus), respectively. Desvenlafaxine apparent permeability (Papp) at varying apical pH was investigated using the Caco-2 cell line and extrapolated to effective intestinal permeability (Peff) in human duodenum, jejunum, ileum and colon. Desvenlafaxine pKa-values and octanol-water partition coefficients (Do:w) were determined experimentally. Due to predicted rapid dissolution after IRF administration, desvenlafaxine was predicted to be available for permeation in the duodenum. Desvenlafaxine Do:w and Papp increased approximately 13-fold when increasing apical pH from 5.5 to 7.4. Desvenlafaxine Peff thus increased with pH down the small intestine. Consequently, desvenlafaxine absorption from an IRF appears rate-limited by low Peff in the upper small intestine, which "delays" the predicted
The objective of this work is to use the Exposure Related Dose Estimating Model (ERDEM) and quantitative structure-activity relationship (QSAR) models to develop an assessment tool for human exposure assessment to triazole fungicides. A dermal exposure route is used for the physi...
NASA Technical Reports Server (NTRS)
Belcastro, Christine M.
1998-01-01
Robust control system analysis and design is based on an uncertainty description, called a linear fractional transformation (LFT), which separates the uncertain (or varying) part of the system from the nominal system. These models are also useful in the design of gain-scheduled control systems based on Linear Parameter Varying (LPV) methods. Low-order LFT models are difficult to form for problems involving nonlinear parameter variations. This paper presents a numerical computational method for constructing and LFT model for a given LPV model. The method is developed for multivariate polynomial problems, and uses simple matrix computations to obtain an exact low-order LFT representation of the given LPV system without the use of model reduction. Although the method is developed for multivariate polynomial problems, multivariate rational problems can also be solved using this method by reformulating the rational problem into a polynomial form.
NASA Astrophysics Data System (ADS)
Weber, Robin; Carrassi, Alberto; Guemas, Virginie; Doblas-Reyes, Francisco; Volpi, Danila
2014-05-01
Full Field (FFI) and Anomaly Initialisation (AI) are two schemes used to initialise seasonal-to-decadal (s2d) prediction. FFI initialises the model on the best estimate of the actual climate state and minimises the initial error. However, due to inevitable model deficiencies, the trajectories drift away from the observations towards the model's own attractor, inducing a bias in the forecast. AI has been devised to tackle the impact of drift through the addition of this bias onto the observations, in the hope of gaining an initial state closer to the model attractor. Its goal is to forecast climate anomalies. The large variety of experimental setups, global coupled models, and observational networks adopted world-wide have led to varying results with regards to the relative performance of AI and FFI. Our research is firstly motivated in a comparison of these two initialisation approaches under varying circumstances of observational errors, observational distributions, and model errors. We also propose and compare two advanced schemes for s2d prediction. Least Square Initialisation (LSI) intends to propagate observational information of partially initialized systems to the whole model domain, based on standard practices in data assimilation and using the covariance of the model anomalies. Exploring the Parameters Uncertainty (EPU) is an online drift correction technique applied during the forecast run after initialisation. It is designed to estimate, and subtract, the bias in the forecast related to parametric error. Experiments are carried out using an idealized coupled dynamics in order to facilitate better control and robust statistical inference. Results show that an improvement of FFI will necessitate refinements in the observations, whereas improvements in AI are subject to model advances. A successful approximation of the model attractor using AI is guaranteed only when the differences between model and nature probability distribution functions (PDFs) are
Gharti, KP; Thapa, P; Budhathoki, U; Bhargava, A
2012-01-01
The present study was carried out with an objective of preparation and in vitro evaluation of floating tablets of hydroxypropyl methyl cellulose (HPMC) and polyethylene oxide (PEO) using ranitidine hydrochloride as a model drug. The floating tablets were based on effervescent approach using sodium bicarbonate a gas generating agent. The tablets were prepared by dry granulation method. The effect of polymers concentration and viscosity grades of HPMC on drug release profile was evaluated. The effect of sodium bicarbonate and stearic acid on drug release profile and floating properties were also investigated. The result of in vitro dissolution study showed that the drug release profile could be sustained by increasing the concentration of HPMC K15MCR and Polyox WSR303. The formulation containing HPMC K15MCR and Polyox WSR303 at the concentration of 13.88% showed 91.2% drug release at the end of 24 hours. Changing the viscosity grade of HPMC from K15MCR to K100MCR had no significant effect on drug release profile. Sodium bicarbonate and stearic acid in combination showed no significant effect on drug release profile. The formulations containing sodium bicarbonate 20 mg per tablet showed desired buoyancy (floating lag time of about 2 minutes and total floating time of >24 hours). The present study shows that polymers like HPMC K15MCR and Polyox WSR303 in combination with sodium bicarbonate as a gas generating agent can be used to develop sustained release floating tablets of ranitidine hydrochloride. PMID:23493037
Wang, Houyong; Li, Qiang; Deng, Wenwen; Omari-Siaw, E; Wang, Qilong; Wang, Shicheng; Wang, Shengli; Cao, Xia; Xu, Ximing; Yu, Jiangnan
2015-03-01
The objective of this study was to formulate a self-nanoemulsifying oral drug delivery system (SNEDDS) for the poorly water-soluble trans-Cinnamic acid (t-CA SNEDDS) that could be evaluated for its antihyperglycemic efficacy in comparison to the parent t-CA in an alloxan-induced diabetic rat model. A SNEDDS formulation consisting of 60% surfactant (Kolliphor EL), 10% co-surfactant (PEG 400) and 30% oil (isopropyl myristate) proved to be optimal. t-CA SNEDDS (80 mg/kg, p.o.), t-CA suspension (80 mg/kg, p.o.), and Metformin Hydrochloride Tablets (230 mg/kg, p.o.) were administer qdfor 30 days to diabetic rats. After treatment the body weight of diabetic rats was increased, blood glucose levels, total cholesterol, and triglyceride in the serum tended to be normalized, while the levels of alanine aminotransferase and aspartate aminotransferase were markedly decreased. The effects of t-CA SNEDDS were superior to that of the t-CA suspension. The present study demonstrated that t-CA was effective in attenuating the effects of alloxan treatment and that t-CA SNEDDS with a more favorable absorption and enhanced bioavailability is more effective than t-CA. PMID:25847843
Gharti, Kp; Thapa, P; Budhathoki, U; Bhargava, A
2012-10-01
The present study was carried out with an objective of preparation and in vitro evaluation of floating tablets of hydroxypropyl methyl cellulose (HPMC) and polyethylene oxide (PEO) using ranitidine hydrochloride as a model drug. The floating tablets were based on effervescent approach using sodium bicarbonate a gas generating agent. The tablets were prepared by dry granulation method. The effect of polymers concentration and viscosity grades of HPMC on drug release profile was evaluated. The effect of sodium bicarbonate and stearic acid on drug release profile and floating properties were also investigated. The result of in vitro dissolution study showed that the drug release profile could be sustained by increasing the concentration of HPMC K15MCR and Polyox WSR303. The formulation containing HPMC K15MCR and Polyox WSR303 at the concentration of 13.88% showed 91.2% drug release at the end of 24 hours. Changing the viscosity grade of HPMC from K15MCR to K100MCR had no significant effect on drug release profile. Sodium bicarbonate and stearic acid in combination showed no significant effect on drug release profile. The formulations containing sodium bicarbonate 20 mg per tablet showed desired buoyancy (floating lag time of about 2 minutes and total floating time of >24 hours). The present study shows that polymers like HPMC K15MCR and Polyox WSR303 in combination with sodium bicarbonate as a gas generating agent can be used to develop sustained release floating tablets of ranitidine hydrochloride. PMID:23493037
NASA Technical Reports Server (NTRS)
Bates, J. R.; Moorthi, S.; Higgins, R. W.
1993-01-01
An adiabatic global multilevel primitive equation model using a two time-level, semi-Lagrangian semi-implicit finite-difference integration scheme is presented. A Lorenz grid is used for vertical discretization and a C grid for the horizontal discretization. The momentum equation is discretized in vector form, thus avoiding problems near the poles. The 3D model equations are reduced by a linear transformation to a set of 2D elliptic equations, whose solution is found by means of an efficient direct solver. The model (with minimal physics) is integrated for 10 days starting from an initialized state derived from real data. A resolution of 16 levels in the vertical is used, with various horizontal resolutions. The model is found to be stable and efficient, and to give realistic output fields. Integrations with time steps of 10 min, 30 min, and 1 h are compared, and the differences are found to be acceptable.
NASA Astrophysics Data System (ADS)
Sanfélix, V.; Escrig, A.; López-Lilao, A.; Celades, I.; Monfort, E.
2015-05-01
Source inversion by dispersion modelling of fugitive particulate matter (PM) emissions entails considerable difficulty. Fugitive PM sources are rarely steady or point sources. They occur near the ground, where there are high vertical gradients of wind velocity and potential temperature. To resolve the source from the background concentrations, measurements need to be conducted very close to the source. In this study, a dispersion model was developed that consists of numerically solving the pollutant transport equation, while incorporating the Monin-Obukhov similarity theory. By using this numerical approach, in contrast to Gaussian dispersion models, wind shear effects and plume meandering were accounted for directly. A series of controlled experiments were conducted, in which the fugitive PM sources were parameterized as much as possible. The developed model was used to obtain operation-specific PM10 emission factors (EFs). This is the first of two articles describing the model and the field campaigns in which it was applied to determine the EFs. Part I describes the mathematical model and its application to two relatively simple sources.
NASA Technical Reports Server (NTRS)
Lee, Jong-Won; Harris, Charles E.
1990-01-01
A mathematical model based on the Euler-Bermoulli beam theory is proposed for predicting the effective Young's moduli of piecewise isotropic composite laminates with local ply curvatures in the main load-carrying layers. Strains in corrugated layers, in-phase layers, and out-of-phase layers are predicted for various geometries and material configurations by assuming matrix layers as elastic foundations of different spring constants. The effective Young's moduli measured from corrugated aluminum specimens and aluminum/epoxy specimens with in-phase and out-of-phase wavy patterns coincide very well with the model predictions. Moire fringe analysis of an in-phase specimen and an out-of-phase specimen are also presented, confirming the main assumption of the model related to the elastic constraint due to the matrix layers. The present model is also compared with the experimental results and other models, including the microbuckling models, published in the literature. The results of the present study show that even a very small-scale local ply curvature produces a noticeable effect on the mechanical constitutive behavior of a laminated composite.
Peters, Arne
2016-01-01
The enduring stages of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis are infective juveniles, which require a high humidity and sufficient ventilation for survival. Formulations must account for these requirements. Nematodes may be formulated inside the insects in which they reproduced or they need to be cleaned and mixed with a suitable binder to maintain humidity but allowing for gas exchange. Another method for formulation is the encapsulation in beads of Ca-alginate. Generic procedures for these formulation techniques are described. PMID:27565496
Psychiatrists' use of formulation
Hughes, Patricia M.
2016-01-01
Both psychologists and psychiatrists are trained to write formulations of their patients' illnesses, with some differences in how they do this. Psychologists focus on psychological understanding, while psychiatrists' formulation brings together aetiology, functioning and a management plan. Mohtashemi et al's study records how some psychiatrists understand formulation and its usefulness. Time pressure was an important barrier to making a full formulation, and some believed the medical role of the psychiatrist was a priority. The study illustrates some of the challenges facing psychiatrists working in the NHS in terms of maintaining high clinical standards and a holistic approach to patient care. PMID:27512593
NASA Astrophysics Data System (ADS)
Demory, Marie-Estelle; Matsueda, Mio; Vidale, Pier Luigi; Roberts, Malcolm
2013-04-01
Changes in the global energy budget of the Earth come from changes in the net solar radiation or in the outgoing longwave radiation and can have profound impacts on global-scale features, such as the global hydrological cycle. These fluxes strongly depend on clouds, aerosols and greenhouse gases, whose interactions with the climate system are mainly parameterised in General Circulation Models (GCM). As more and more GCMs are being developed at higher horizontal resolutions, the sensitivity of processes of the climate system to resolution are being explored, over different timescales and spatial scales. In this study, we assess the sensitivity of the simulated global annual energy budget to horizontal resolution in three different atmospheric GCMs that have a hierarchy of similar formulations with different resolutions: the UK Met Office Hadley Centre's HadGEM1-A and HadGEM3-A models, and the Japanese Meteorological Research Institute's MRI-AGCM3.2 model. We will show that, in present-day climate, the global energy budget is well simulated by the three models considered, compared to recently published estimates of the Earth's global energy budget. We will also show that the global energy budget is insensitive to horizontal resolution in both HadGEM1-A and HadGEM3-A, but is sensitive to resolution in MRI-AGCM3.2. These findings emphasise that the sensitivity of the simulated global energy budget to horizontal resolution may depend on model formulation, and we will also present primarily results on the cause of this dependency, whether it depends on tuning, on different resolution adjustments in the parameterisation schemes or on the dynamics of the models. These results show further evidence that the diversity of models' behaviour can simply depend on their resolution, a result that is well known for weather-like features (cyclones, precipitation extremes, blockings), and that this difference in behaviour can also start in the primary driver of the Earth's climate
Cierniak, Robert; Lorent, Anna
2016-09-01
The main aim of this paper is to investigate properties of our originally formulated statistical model-based iterative approach applied to the image reconstruction from projections problem which are related to its conditioning, and, in this manner, to prove a superiority of this approach over ones recently used by other authors. The reconstruction algorithm based on this conception uses a maximum likelihood estimation with an objective adjusted to the probability distribution of measured signals obtained from an X-ray computed tomography system with parallel beam geometry. The analysis and experimental results presented here show that our analytical approach outperforms the referential algebraic methodology which is explored widely in the literature and exploited in various commercial implementations. PMID:27289536
ERIC Educational Resources Information Center
Pinkerton, Steven D.; Abramson, Paul R.
1994-01-01
Estimates of the reproductive rate of infection with the human immunodeficiency virus (HIV), obtained through a Bernoulli process model, indicate that decreasing the infectivity of the virus, through the use of condoms, for example, is more effective at reducing the infection rate than is limiting the number of sexual partners. (SLD)
Generally, analyses of longitudinal studies of chronic disease risks do not directly model the change with time of risk factor values and the interactions of those changes with risk levels. Failure to account for such process characteristics can lead to incorrect inferences about...
Haidvogel, D.B.; Arango, H.; Budgell, W.P.; Cornuelle, B.D.; Curchitser, E.; Di, Lorenzo E.; Fennel, K.; Geyer, W.R.; Hermann, A.J.; Lanerolle, L.; Levin, J.; McWilliams, J.C.; Miller, A.J.; Moore, A.M.; Powell, T.M.; Shchepetkin, A.F.; Sherwood, C.R.; Signell, R.P.; Warner, J.C.; Wilkin, J.
2008-01-01
Systematic improvements in algorithmic design of regional ocean circulation models have led to significant enhancement in simulation ability across a wide range of space/time scales and marine system types. As an example, we briefly review the Regional Ocean Modeling System, a member of a general class of three-dimensional, free-surface, terrain-following numerical models. Noteworthy characteristics of the ROMS computational kernel include: consistent temporal averaging of the barotropic mode to guarantee both exact conservation and constancy preservation properties for tracers; redefined barotropic pressure-gradient terms to account for local variations in the density field; vertical interpolation performed using conservative parabolic splines; and higher-order, quasi-monotone advection algorithms. Examples of quantitative skill assessment are shown for a tidally driven estuary, an ice-covered high-latitude sea, a wind- and buoyancy-forced continental shelf, and a mid-latitude ocean basin. The combination of moderate-order spatial approximations, enhanced conservation properties, and quasi-monotone advection produces both more robust and accurate, and less diffusive, solutions than those produced in earlier terrain-following ocean models. Together with advanced methods of data assimilation and novel observing system technologies, these capabilities constitute the necessary ingredients for multi-purpose regional ocean prediction systems. ?? 2007 Elsevier Inc. All rights reserved.
NASA Astrophysics Data System (ADS)
Varady, Mark; Bringuier, Stefan; Pearl, Thomas; Stevenson, Shawn; Mantooth, Brent
Decontamination of polymers exposed to chemical warfare agents (CWA) often proceeds by application of a liquid solution. Absorption of some decontaminant components proceed concurrently with extraction of the CWA, resulting in multicomponent diffusion in the polymer. In this work, the Maxwell-Stefan equations were used with the Flory-Huggins model of species activity to mathematically describe the transport of two species within a polymer. This model was used to predict the extraction of the nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX) from a silicone elastomer into both water and methanol. Comparisons with experimental results show good agreement with minimal fitting of model parameters from pure component uptake data. Reaction of the extracted VX with sodium hydroxide in the liquid-phase was also modeled and used to predict the overall rate of destruction of VX. Although the reaction proceeds more slowly in the methanol-based solution compared to the aqueous solution, the extraction rate is faster due to increasing VX mobility as methanol absorbs into the silicone, resulting in an overall faster rate of VX destruction.
NASA Technical Reports Server (NTRS)
Flagan, R. C.; Appleton, J. P.
1973-01-01
A stochastic model of turbulent mixing was developed for a reactor in which mixing is represented by n-body fluid particle interactions. The model was used to justify the assumption (made in previous investigations of the role of turbulent mixing on burner generated thermal nitric oxide and carbon monoxide emissions) that for a simple plug flow reactor, composition nonuniformities can be described by a Gaussian distribution function in the local fuel:air equivalence ratio. Recent extensions of this stochastic model to include the combined effects of turbulent mixing and secondary air entrainment on thermal generation of nitric oxide in gas turbine combustors are discussed. Finally, rate limited upper and lower bounds of the nitric oxide produced by thermal fixation of molecular nitrogen and oxidation of organically bound fuel nitrogen are estimated on the basis of the stochastic model for a plug flow burner; these are compared with experimental measurements obtained using a laboratory burner operated over a wide range of test conditions; good agreement is obtained.
Chessa, S; Huatan, H; Levina, M; Mehta, R Y; Ferrizzi, D; Rajabi-Siahboomi, A R
2014-05-15
Characterisation of the effect of food on the bio-performance of modified and extended release dosage forms can be very challenging due to the need to replicate the dynamic biochemical conditions of the human gut as well as the complex physical processing modalities under fed state. Classical compendial methods are useful for testing the quality of pharmaceutical dosage forms but typically have limitations in the accurate prediction of food-effect in-vivo. Preliminary evaluation of the Dynamic Gastric Model (DGM) shows that it can provide substantially more detailed mechanistic information on dosage form properties compared to conventional compendial testing. The potential effect of food on the drug release and physical properties of a hydrophilic matrix formulation containing a model drug, hydrochlorothiazide, was studied using compendial methods, bio-relevant media and the DGM (in combination with an off-line intestinal model). Whilst the compendial methods with biorelevant media provided good correlation with the dissolution rates observed using the DGM/intestinal model under simulated fasted state, the quantification of simulated fed state performance changes was much more challenging using the compendial methods. Classical compendial studies using biorelevant FeSSIF and FaSSIF media could not readily discern differences in dissolution performance under fasted and fed states; however, the DGM could detect significant changes in both physical properties as well as drug release performance under fed state processing. PMID:24657141
Wajsowicz, R.C. )
1993-04-01
Subgrid-scale dissipation of momentum in numerical models of the large-scale ocean circulation is commonly parameterized as a viscous diffusion resulting from the divergence of a stress tensor of the form [omega] = Au. The form of the fourth-order coefficient tensor A is derived for anisotropic dissipation with an axis of rotational symmetry. Sufficient conditions for A to be positive definite for incompressible flows, so guaranteeing a net positive dissipation of kinetic energy, are found. The divergence of the stress tensor, in Cartesian and spherical polar coordinates, is given for A with constant and spatially varying elements. A consistent form of A and [omega] for use in models based on the Arakawa B- and C-grids is also derived. 16 refs.
NASA Astrophysics Data System (ADS)
Bounceur, Nabila; Crucifix, Michel
2010-05-01
The climate is a multivariable dynamic complex system, governed by equations which are strongly nonlinear. The space-time modes of climatic variability extend on a very broad scale and constitute a major difficulty to represent this variability over long time-scales. It is generally decided to separate the dynamics of the slow components (ice sheets, carbon cycle, deep oceans) which have a time scale of about thousand of years and more, from those of the fast components (atmosphere, mixed layer, earth and ice surface) for which the time scale is for about some years. In this framework, the time-evolution of the slow components depends on the statistics of the fast components, and the latter are controlled by the slow components and the external forcing particularly astronomical ones characterised by the variation of the orbital parameters: Obliquity, precession and eccentricity. The statistics of the fast components of the climate could in principle be estimated with a general circulation model of the atmosphere and ocean. However, the demand on computing resources would be far too excessive. Given the complexity of the climatic system, the great number of dynamic equations which govern it and its degree of nonlinearity we are interested in the statistical reduction rather than an analytical one. The order reduction problem is equivalent to approximator construction. We will focus on neural networks because they constitute very powerful estimators in presence of non-linearity. The training of this network would be done using the output of the climate model of intermediate complexity "LoveClim" developed and available in the Institute of Astronomy and Geophysics G.Lemaître in Belgium as a first step of statistical reduction. The output of the model are first reduced using different methods of reduction order going from linear ones as principal component analysis (PCA) and empirical orthogonal functions (EOF) to non linear ones as Non Linear Principal component
Haynes, Mark; Verweij, Sacha A. M.; Moghaddam, Mahta; Carson, Paul L.
2014-01-01
A self-contained source characterization method for commercial ultrasound probes in transmission acoustic inverse scattering is derived and experimentally tested. The method is based on modified scattered field volume integral equations that are linked to the source-scattering transducer model. The source-scattering parameters are estimated via pair-wise transducer measurements and the nonlinear inversion of an acoustic propagation model that is derived. This combination creates a formal link between the transducer characterization and the inverse scattering algorithm. The method is tested with two commercial ultrasound probes in a transmission geometry including provisions for estimating the probe locations and aligning a robotic rotator. The transducer characterization results show that the nonlinear inversion fit the measured data well. The transducer calibration and inverse scattering algorithm are tested on simple targets. Initial images show that the recovered contrasts are physically consistent with expected values. PMID:24569251
NASA Astrophysics Data System (ADS)
Saubanère, Matthieu; Lepetit, Marie Bernadette; Pastor, G. M.
2016-07-01
The interaction energy W [γ ] of the Hubbard model is regarded as a functional of the single-particle density matrix γ in the framework of lattice density-functional theory. The local character of the Hubbard interaction is exploited to express W as a sum of local contributions ωi[γ ] , for which a simple semilocal scaling approximation is proposed. The method is applied to the ionic Hubbard model on one- and two-dimensional lattices with homogeneous and inhomogeneous Coulomb repulsions. Results are given for the kinetic and Coulomb energies, interatomic charge transfers, local magnetic moments, and charge gaps. Goals and limitations of the functional are discussed by comparison with exact results.
NASA Astrophysics Data System (ADS)
Viparelli, E.; Hernandez Moreira, R. R.; Blom, A.
2015-12-01
A perusal of the literature on bedload transport revealed that, notwithstanding the large number of studies on bedform morphology performed in the past decades, the upper plane bed regime has not been thoroughly investigated and the distinction between the upper plane bed and sheet flow transport regimes is still poorly defined. Previous experimental work demonstrated that the upper plane bed regime is characterized by long wavelength and small amplitude bedforms that migrate downstream. These bedforms, however, were not observed in experiments on sheet flow transport suggesting that the upper plane bed and the sheet flow are two different regimes. We thus designed and performed experiments in a sediment feed flume in the hydraulic laboratory of the Department of Civil and Environmental Engineering at the University of South Carolina at Columbia to study the transition from upper plane bed to sheet flow regime. Periodic measurements of water surface and bed elevation, bedform geometry and thicknesses of the bedload layer were performed by eyes, and with cameras, movies and a system of six ultrasonic probes that record the variations of bed elevation at a point over time. We used the time series of bed elevations to determine the probability functions of bed elevation. These probability functions are implemented in a continuous model of river morphodynamics, i.e. a model that does not use the active layer approximation to describe the sediment fluxes between the bedload and the deposit and that should thus be able to capture the details of the vertical and streamwise variation of the deposit grain size distribution. This model is validated against the experimental results for the case of uniform material. We then use the validated model in the attempt to study if and how the spatial distribution of grain sizes in the deposit changes from upper plane bed regime to sheet flow and if these results are influenced by the imposed rates of base level rise.
Hatfield, L.A.; Gutreuter, S.; Boogaard, M.A.; Carlin, B.P.
2011-01-01
Estimation of extreme quantal-response statistics, such as the concentration required to kill 99.9% of test subjects (LC99.9), remains a challenge in the presence of multiple covariates and complex study designs. Accurate and precise estimates of the LC99.9 for mixtures of toxicants are critical to ongoing control of a parasitic invasive species, the sea lamprey, in the Laurentian Great Lakes of North America. The toxicity of those chemicals is affected by local and temporal variations in water chemistry, which must be incorporated into the modeling. We develop multilevel empirical Bayes models for data from multiple laboratory studies. Our approach yields more accurate and precise estimation of the LC99.9 compared to alternative models considered. This study demonstrates that properly incorporating hierarchical structure in laboratory data yields better estimates of LC99.9 stream treatment values that are critical to larvae control in the field. In addition, out-of-sample prediction of the results of in situ tests reveals the presence of a latent seasonal effect not manifest in the laboratory studies, suggesting avenues for future study and illustrating the importance of dual consideration of both experimental and observational data. ?? 2011, The International Biometric Society.
Hatfield, Laura A.; Gutreuter, Steve; Boogaard, Michael A.; Carlin, Bradley P.
2011-01-01
Summary Estimation of extreme quantal-response statistics, such as the concentration required to kill 99.9% of test subjects (LC99.9), remains a challenge in the presence of multiple covariates and complex study designs. Accurate and precise estimates of the LC99.9 for mixtures of toxicants is critical to ongoing control of a parasitic invasive species, the sea lamprey, in the Laurentian Great Lakes of North America. The toxicity of those chemicals is affected by local and temporal variations in water chemistry, which must be incorporated into the modeling. We develop multilevel empirical Bayes models for data from multiple laboratory studies. Our approach yields more accurate and precise estimation of the LC99.9 compared to alternative models considered. This study demonstrates that properly incorporating hierarchical structure in laboratory data yields better estimates of LC99.9 stream treatment values that are critical to larvae control in the field. In addition, out-of-sample prediction of the results of in situ tests reveals the presence of a latent seasonal effect not manifest in the laboratory studies, suggesting avenues for future study and illustrating the importance of dual consideration of both experimental and observational data. PMID:21361894
Lee, Plato C.; Parks, Eric K.; Moran, Brian J
2003-12-31
An innovative (and yet simple) dosimetric model is proposed that provides a semi-analytical solution to the total activity-volume relationship in ultrasound-guided transperineal prostate implant. This dosimetric model is based on 4 simple assumptions. First, the prostate target volume is approximated as a sphere. Second, the urethra is presumed to transverse through the center of the prostate target volume. Third, peripheral loading is applied as the seed-loading technique. Fourth, as the major innovation of the proposed model, the radial dose function of the Iodine-125 {sup 125}I seed is forced to fit a simple power function of the distance r. Pursuant to the third assumption, the peripherally-loaded seeds also define a spherical volume defined as the loading volume w. Also pursuant to the fourth assumption, the radial dose function is expressed as 1.139*r{sup -0.474} for r = 1.5 to 2.5 cm. Thereafter, a simple analytical power-law equation, A = 1.630* w{sup 0.825}, for the relationship between the total activity A in mCi and the loading volume w in cc is derived for {sup 125}I monotherapy. Isodose plans for loading volumes corresponding to r = 1.5, 1.8, 2.2, and 2.5 cm were performed. The maximal isodose coverage volume {sub max}V100 was calculated for each case and was found to be on the average 65% larger than the loading volume w. Matching prostate target volume V to the loading volume w therefore yields a generous implant (with a margin of approximately 3.3 mm). Conversely, matching the prostate target volume V to the {sub max}V100 yields a tight implant (with 0.0 mm or no margin). Matching the prostate target volume V to a midpoint between the loading volume w and {sub max}V100 yields a moderate implant (with approximately 1- to 2-mm margin). Three individual equations are derived for each type of implants: A = 1.630* V{sup 0.825}, A = 1.288* V{sup 0.825}, or A = 1.078 V{sup 0.825} for generous, tight, or moderate implants, respectively. Patient data at the
Laval, Guillaume; Patin, Etienne; Barreiro, Luis B.; Quintana-Murci, Lluís
2010-01-01
Background Estimating the historical and demographic parameters that characterize modern human populations is a fundamental part of reconstructing the recent history of our species. In addition, the development of a model of human evolution that can best explain neutral genetic diversity is required to identify confidently regions of the human genome that have been targeted by natural selection. Methodology/Principal Findings We have resequenced 20 independent noncoding autosomal regions dispersed throughout the genome in 213 individuals from different continental populations, corresponding to a total of ∼6 Mb of diploid resequencing data. We used these data to explore and co-estimate an extensive range of historical and demographic parameters with a statistical framework that combines the evaluation of multiple models of human evolution via a best-fit approach, followed by an Approximate Bayesian Computation (ABC) analysis. From a methodological standpoint, evaluating the accuracy of the parameter co-estimation allowed us to identify the most accurate set of statistics to be used for the estimation of each of the different historical and demographic parameters characterizing recent human evolution. Conclusions/Significance Our results support a model in which modern humans left Africa through a single major dispersal event occurring ∼60,000 years ago, corresponding to a drastic reduction of ∼5 times the effective population size of the ancestral African population of ∼13,800 individuals. Subsequently, the ancestors of modern Europeans and East Asians diverged much later, ∼22,500 years ago, from the population of ancestral migrants. This late diversification of Eurasians after the African exodus points to the occurrence of a long maturation phase in which the ancestral Eurasian population was not yet diversified. PMID:20421973
NASA Technical Reports Server (NTRS)
Chao, W. C.
1982-01-01
With appropriate modifications, a recently proposed explicit-multiple-time-step scheme (EMTSS) is incorporated into the UCLA model. In this scheme, the linearized terms in the governing equations that generate the gravity waves are split into different vertical modes. Each mode is integrated with an optimal time step, and at periodic intervals these modes are recombined. The other terms are integrated with a time step dictated by the CFL condition for low-frequency waves. This large time step requires a special modification of the advective terms in the polar region to maintain stability. Test runs for 72 h show that EMTSS is a stable, efficient and accurate scheme.
Battistel, O. A.; Dallabona, G.
2009-10-15
The predictive power of the Nambu-Jona-Lasinio model is considered in the light of a novel strategy to handle the divergences typical of perturbative calculations. The referred calculational strategy eliminates unphysical dependencies on the arbitrary choices for the routing of internal momenta and symmetry violating terms. In the present work we extend a previous one on the same issue by including vector interactions and performing the discussion in a more general context: the role of scale arbitrariness for the consistency of the calculations is considered. We show that the imposition of arbitrary scale independence for the consistent regularized amplitudes lead to additional properties for the irreducible divergent objects. These properties allow us to parametrize the remaining freedom in terms of a unique constant where resides all the arbitrariness involved. By searching for the best value for the arbitrary parameter we find a critical condition for the existence of an acceptable physical value for the dynamically generated quark mass. Such critical condition fixes the remaining arbitrariness turning the Nambu-Jona-Lasinio into a predictive model in the sense that its phenomenological consequences do not depend on possible choices made in intermediary steps. Numerical results are obtained for physical quantities like the vector and axial-vector masses and their coupling constants as genuine predictions.
Luo, Qizhi; Li, Wei; Zou, Xin; Dang, Yongming; Wu, Jun
2015-01-01
Acute burn injuries are among the most devastating forms of trauma and lead to significant morbidity and mortality. Appropriate fluid resuscitation after severe burn, specifically during the first 48 hours following injury, is considered as the single most important therapeutic intervention in burn treatment. Although many formulas have been developed to estimate the required fluid amount in severe burn patients, many lines of evidence showed that patients still receive far more fluid than formulas recommend. Overresuscitation, which is known as “fluid creep,” has emerged as one of the most important problems during the initial period of burn care. If fluid titration can be personalized and automated during the resuscitation phase, more efficient burn care and outcome will be anticipated. In the present study, a dynamic urine output based infusion rate prediction model was developed and validated during the initial 48 hours in severe thermal burn adult patients. The experimental results demonstrated that the developed dynamic fluid resuscitation model might significantly reduce the total fluid volume by accurately predicting hourly urine output and has the potential to aid fluid administration in severe burn patients. PMID:26090415
NASA Astrophysics Data System (ADS)
Bekal, Anish; Srinivasan, Balaji
2012-06-01
Accurate modeling of dynamic optical interactions such as saturation and re-absorption in highly doped waveguide amplifiers requires solving a stiff system of ordinary differential equations (ODEs). Traditional ODE solvers including Range-Kutta methods are computationally ill-suited for such applications. In this paper, we derive and apply predictor - corrector adaptive Adam-Bashforth scheme for modeling the population dynamics in Erbium - Doped Fiber Amplifiers (EDFA). Predictor and corrector equations for adaptive Adam-Bashforth have been derived by using Lagrange polynomial as basis rather than the Newton polynomials used in constant stepsize Adam-Bashforth scheme. Convergence and stability analysis conducted on the scheme shows that the method has similar characteristics as that of constant step-size conventional Adam-Bashforth methods for small changes in step sizes. Solutions have been validated by re-generating the absorption and emission coefficients for doped fibers with two different doping concentrations, which is found to match with the manufacturer datasheet. This method is compared with other method like Euler and the optimum order of predictor and corrector is estimated. The result show that this modified form of the scheme results in 75% reduction in step-size to maintain an relative accuracy level of 10-3 as compared to adaptive Euler method. Finally, different orders were compared by using ratio of step-size and number of operations per step as a metric for Figure of Merit (FOM). FOM analysis shows that use of higher order methods are not efficient in reducing the number of steps required to obtain accurate results. It is found that the scheme with both second order predictor and corrector is the most efficient computationally. However, in terms of accuracy second order predictor and third order corrector is more suitable with only a marginal degradation of FOM.
ERIC Educational Resources Information Center
Paek, Insu; Wilson, Mark
2011-01-01
This study elaborates the Rasch differential item functioning (DIF) model formulation under the marginal maximum likelihood estimation context. Also, the Rasch DIF model performance was examined and compared with the Mantel-Haenszel (MH) procedure in small sample and short test length conditions through simulations. The theoretically known…
Awotwe-Otoo, David; Agarabi, Cyrus; Khan, Mansoor A
2014-07-01
The aim of the present study was to apply an integrated process analytical technology (PAT) approach to control and monitor the effect of the degree of supercooling on critical process and product parameters of a lyophilization cycle. Two concentrations of a mAb formulation were used as models for lyophilization. ControLyo™ technology was applied to control the onset of ice nucleation, whereas tunable diode laser absorption spectroscopy (TDLAS) was utilized as a noninvasive tool for the inline monitoring of the water vapor concentration and vapor flow velocity in the spool during primary drying. The instantaneous measurements were then used to determine the effect of the degree of supercooling on critical process and product parameters. Controlled nucleation resulted in uniform nucleation at lower degrees of supercooling for both formulations, higher sublimation rates, lower mass transfer resistance, lower product temperatures at the sublimation interface, and shorter primary drying times compared with the conventional shelf-ramped freezing. Controlled nucleation also resulted in lyophilized cakes with more elegant and porous structure with no visible collapse or shrinkage, lower specific surface area, and shorter reconstitution times compared with the uncontrolled nucleation. Uncontrolled nucleation however resulted in lyophilized cakes with relatively lower residual moisture contents compared with controlled nucleation. TDLAS proved to be an efficient tool to determine the endpoint of primary drying. There was good agreement between data obtained from TDLAS-based measurements and SMART™ technology. ControLyo™ technology and TDLAS showed great potential as PAT tools to achieve enhanced process monitoring and control during lyophilization cycles. PMID:24840395
Thompson, Mitchell G.; Truong-Le, Vu; Alamneh, Yonas A.; Black, Chad C.; Anderl, Jeff; Honnold, Cary L.; Pavlicek, Rebecca L.; Abu-Taleb, Rania; Wise, Matthew C.; Hall, Eric R.; Wagar, Eric J.; Patzer, Eric
2015-01-01
Skin and soft tissue infections (SSTIs) are a common occurrence in health care facilities with a heightened risk for immunocompromised patients. Klebsiella pneumoniae has been increasingly implicated as the bacterial agent responsible for SSTIs, and treatment can be challenging as more strains become multidrug resistant (MDR). Therefore, new treatments are needed to counter this bacterial pathogen. Gallium complexes exhibit antimicrobial activity and are currently being evaluated as potential treatment for bacterial infections. In this study, we tested a topical formulation containing gallium citrate (GaCi) for the treatment of wounds infected with K. pneumoniae. First, the MIC against K. pneumoniae ranged from 0.125 to 2.0 μg/ml GaCi. After this in vitro efficacy was established, two topical formulations with GaCi (0.1% [wt/vol] and 0.3% [wt/vol]) were tested in a murine wound model of MDR K. pneumoniae infection. Gross pathology and histopathology revealed K. pneumoniae-infected wounds appeared to close faster with GaCi treatment and were accompanied by reduced inflammation compared to those of untreated controls. Similarly, quantitative indications of infection remediation, such as reduced weight loss and wound area, suggested that treatment improved outcomes compared to those of untreated controls. Bacterial burdens were measured 1 and 3 days following inoculation, and a 0.5 to 1.5 log reduction of CFU was observed. Lastly, upon scanning electron microscopy analysis, GaCi treatment appeared to prevent biofilm formation on dressings compared to those of untreated controls. These results suggest that with more preclinical testing, a topical application of GaCi may be a promising alternative treatment strategy for K. pneumoniae SSTI. PMID:26239978
Thompson, Mitchell G; Truong-Le, Vu; Alamneh, Yonas A; Black, Chad C; Anderl, Jeff; Honnold, Cary L; Pavlicek, Rebecca L; Abu-Taleb, Rania; Wise, Matthew C; Hall, Eric R; Wagar, Eric J; Patzer, Eric; Zurawski, Daniel V
2015-10-01
Skin and soft tissue infections (SSTIs) are a common occurrence in health care facilities with a heightened risk for immunocompromised patients. Klebsiella pneumoniae has been increasingly implicated as the bacterial agent responsible for SSTIs, and treatment can be challenging as more strains become multidrug resistant (MDR). Therefore, new treatments are needed to counter this bacterial pathogen. Gallium complexes exhibit antimicrobial activity and are currently being evaluated as potential treatment for bacterial infections. In this study, we tested a topical formulation containing gallium citrate (GaCi) for the treatment of wounds infected with K. pneumoniae. First, the MIC against K. pneumoniae ranged from 0.125 to 2.0 μg/ml GaCi. After this in vitro efficacy was established, two topical formulations with GaCi (0.1% [wt/vol] and 0.3% [wt/vol]) were tested in a murine wound model of MDR K. pneumoniae infection. Gross pathology and histopathology revealed K. pneumoniae-infected wounds appeared to close faster with GaCi treatment and were accompanied by reduced inflammation compared to those of untreated controls. Similarly, quantitative indications of infection remediation, such as reduced weight loss and wound area, suggested that treatment improved outcomes compared to those of untreated controls. Bacterial burdens were measured 1 and 3 days following inoculation, and a 0.5 to 1.5 log reduction of CFU was observed. Lastly, upon scanning electron microscopy analysis, GaCi treatment appeared to prevent biofilm formation on dressings compared to those of untreated controls. These results suggest that with more preclinical testing, a topical application of GaCi may be a promising alternative treatment strategy for K. pneumoniae SSTI. PMID:26239978
Audits of radiopharmaceutical formulations.
Castronovo, F P
1992-03-01
A procedure for auditing radiopharmaceutical formulations is described. To meet FDA guidelines regarding the quality of radiopharmaceuticals, institutional radioactive drug research committees perform audits when such drugs are formulated away from an institutional pharmacy. All principal investigators who formulate drugs outside institutional pharmacies must pass these audits before they can obtain a radiopharmaceutical investigation permit. The audit team meets with the individual who performs the formulation at the site of drug preparation to verify that drug formulations meet identity, strength, quality, and purity standards; are uniform and reproducible; and are sterile and pyrogen free. This team must contain an expert knowledgeable in the preparation of radioactive drugs; a radiopharmacist is the most qualified person for this role. Problems that have been identified by audits include lack of sterility and apyrogenicity testing, formulations that are open to the laboratory environment, failure to use pharmaceutical-grade chemicals, inadequate quality control methods or records, inadequate training of the person preparing the drug, and improper unit dose preparation. Investigational radiopharmaceutical formulations, including nonradiolabeled drugs, must be audited before they are administered to humans. A properly trained pharmacist should be a member of the audit team. PMID:1598931
Stepan, Jiri; Trujillo Bueno, Javier E-mail: jtb@iac.es
2011-05-10
Although the spectral lines of hydrogen contain valuable information on the physical properties of a variety of astrophysical plasmas, including the upper solar chromosphere, relatively little is known about their scattering polarization signals, whose modification via the Hanle effect may be exploited for magnetic field diagnostics. Here we report on a basic theoretical investigation of the linear polarization produced by scattering processes and the Hanle effect in Ly{alpha}, Ly{beta}, and H{alpha} taking into account multilevel radiative transfer effects in an isothermal stellar atmosphere model, the fine-structure of the hydrogen levels, as well as the impact of collisions with electrons and protons. The main aim of this first paper is to elucidate the key physical mechanisms that control the emergent fractional linear polarization in the three lines, as well as its sensitivity to the perturbers' density and to the strength and structure of microstructured and deterministic magnetic fields. To this end, we apply an efficient radiative transfer code we have developed for performing numerical simulations of the Hanle effect in multilevel systems with overlapping line transitions. For low-density plasmas, such as that of the upper solar chromosphere, collisional depolarization is caused mainly by collisional transitions between the fine-structure levels of the n = 3 level, so that it is virtually insignificant for Ly{alpha} but important for Ly{beta} and H{alpha}. We show the impact of the Hanle effect on the three lines taking into account the radiative transfer coupling between the different hydrogen line transitions. For example, we demonstrate that the linear polarization profile of the H{alpha} line is sensitive to the presence of magnetic field gradients in the line core formation region, and that in solar-like chromospheres selective absorption of polarization components does not play any significant role in the emergent scattering polarization.
Aydogan, Ebru; Comoglu, Tansel; Pehlivanoglu, Bilge; Dogan, Murat; Comoglu, Selcuk; Dogan, Aysegul; Basci, Nursabah
2015-01-01
Pregabalin is an anticonvulsant drug used for neuropathic pain and as an adjunct therapy for partial seizures with or without secondary generalization in adults. In conventional therapy recommended dose for pregabalin is 75 mg twice daily or 50 mg three times a day, with maximum dosage of 600 mg/d. To achieve maximum therapeutic effect with a low risk of adverse effects and to reduce often drug dosing, modified release preparations; such as microspheres might be helpful. However, most of the microencapsulation techniques have been used for lipophilic drugs, since hydrophilic drugs like pregabalin, showed low-loading efficiency and rapid dissolution of compounds into the aqueous continous phase. The purpose of this study was to improve loading efficiency of a water-soluble drug and modulate release profiles, and to test the efficiency of the prepared microspheres with the help of animal modeling studies. Pregabalin is a water soluble drug, and it was encapsulated within anionic acrylic resin (Eudragit S 100) microspheres by water in oil in oil (w/o/o) double emulsion solvent diffusion method. Dichloromethane and corn oil were chosen primary and secondary oil phases, respectively. The presence of internal water phase was necessary to form stable emulsion droplets and it accelerated the hardening of microspheres. Tween 80 and Span 80 were used as surfactants to stabilize the water and corn oil phases, respectively. The optimum concentration of Tween 80 was 0.25% (v/v) and Span 80 was 0.02% (v/v). The volume of the continous phase was affected the size of the microspheres. As the volume of the continous phase increased, the size of microspheres decreased. All microsphere formulations were evaluated with the help of in vitro characterization parameters. Microsphere formulations (P1-P5) exhibited entrapment efficiency ranged between 57.00 ± 0.72 and 69.70 ± 0.49%; yield ranged between 80.95 ± 1.21 and 93.05 ± 1.42%; and mean particle size were
Reactive decontamination formulation
Giletto, Anthony; White, William; Cisar, Alan J.; Hitchens, G. Duncan; Fyffe, James
2003-05-27
The present invention provides a universal decontamination formulation and method for detoxifying chemical warfare agents (CWA's) and biological warfare agents (BWA's) without producing any toxic by-products, as well as, decontaminating surfaces that have come into contact with these agents. The formulation includes a sorbent material or gel, a peroxide source, a peroxide activator, and a compound containing a mixture of KHSO.sub.5, KHSO.sub.4 and K.sub.2 SO.sub.4. The formulation is self-decontaminating and once dried can easily be wiped from the surface being decontaminated. A method for decontaminating a surface exposed to chemical or biological agents is also disclosed.
Formulation techniques for nanofluids.
Rivera-Solorio, Carlos I; Payán-Rodríguez, Luis A; García-Cuéllar, Alejandro J; Ramón-Raygoza, E D; L Cadena-de-la-Peña, Natalia; Medina-Carreón, David
2013-11-01
Fluids with suspended nanoparticles, commonly known as nanofluids, may be formulated to improve the thermal performance of industrial heat transfer systems and applications. Nanofluids may show enhanced thermal and electrical properties such as thermal conductivity, viscosity, heat transfer coefficient, dielectric strength, etc. However, stability problems may arise as nanoparticles usually have the tendency to agglomerate and sediment producing deterioration in the increment of these properties. In this review, we discuss patents that report advances in the formulation of nanofluids including: production methods, selection of components (nanoparticles, base fluid and surfactants), their chemical compositions and morphologies, and characterization techniques. Finally, current and future directions in the development of nanofluid formulation are discussed. PMID:24330043
NASA Astrophysics Data System (ADS)
Kumar, J.; Mills, R. T.; Lichtner, P. C.; Hammond, G. E.
2010-12-01
Fracture dominated flows occur in numerous subsurface geochemical processes and at many different scales in rock pore structures, micro-fractures, fracture networks and faults. Fractured porous media can be modeled as multiple interacting continua which are connected to each other through transfer terms that capture the flow of mass and energy in response to pressure, temperature and concentration gradients. However, the analysis of large-scale transient problems using the multiple interacting continuum approach presents an algorithmic and computational challenge for problems with very large numbers of degrees of freedom. A generalized dual porosity model based on the Dual Continuum Disconnected Matrix approach has been implemented within a massively parallel multiphysics-multicomponent-multiphase subsurface reactive flow and transport code PFLOTRAN. Developed as part of the Department of Energy's SciDAC-2 program, PFLOTRAN provides subsurface simulation capabilities that can scale from laptops to ultrascale supercomputers, and utilizes the PETSc framework to solve the large, sparse algebraic systems that arises in complex subsurface reactive flow and transport problems. It has been successfully applied to the solution of problems composed of more than two billions degrees of freedom, utilizing up to 131,072 processor cores on Jaguar, the Cray XT5 system at Oak Ridge National Laboratory that is the world’s fastest supercomputer. Building upon the capabilities and computational efficiency of PFLOTRAN, we will present an implementation of the multiple interacting continua formulation for fractured porous media along with an application case study.
NASA Astrophysics Data System (ADS)
Jathar, S. H.; Miracolo, M. A.; Presto, A. A.; Donahue, N. M.; Adams, P. J.; Robinson, A. L.
2012-10-01
We present a methodology to model secondary organic aerosol (SOA) formation from the photo-oxidation of unspeciated low-volatility organics (semi-volatile and intermediate volatile organic compounds) emitted by combustion systems. It is formulated using the volatility basis-set approach. Unspeciated low-volatility organics are classified by volatility and then allowed to react with the hydroxyl radical. The new methodology allows for larger reductions in volatility with each oxidation step than previous volatility basis set models, which is more consistent with the addition of common functional groups and similar to those used by traditional SOA models. The methodology is illustrated using data collected during two field campaigns that characterized the atmospheric evolution of dilute gas-turbine engine emissions using a smog chamber. In those experiments, photo-oxidation formed a significant amount of SOA, much of which could not be explained based on the emissions of traditional speciated precursors; we refer to the unexplained SOA as non-traditional SOA (NT-SOA). The NT-SOA can be explained by emissions of unspeciated low-volatility organics measured using sorbents. We show that the parameterization proposed by Robinson et al. (2007) is unable to explain the timing of the NT-SOA formation in the aircraft experiments because it assumes a very modest reduction in volatility of the precursors with every oxidation reaction. In contrast the new method better reproduces the NT-SOA formation. The NT-SOA yields estimated for the unspeciated low-volatility organic emissions in aircraft exhaust are similar to literature data for large n-alkanes and other low-volatility organics. The estimated yields vary with fuel composition (Jet Propellent-8 versus Fischer-Tropsch) and engine load (ground idle versus non-ground idle). The framework developed here is suitable for modeling SOA formation from emissions from other combustion systems.
Ishida, Toshikazu
2005-01-01
In the Japanese post WWII urban planning and design field, concerns for formal features regarding the sequential street-front visual image in new high-density urban spaces have been a rather subordinated subject. Famous New Town schemes such as Tsukuba Science City (1963), or Minato Mirai 21 (1965) for instance, are typical inland and reclaimed land examples that summarize the validity and limitations of functional zoning systems applied to these artificial urban developments for the last half century. In those examples, the interaction between space mobility and land use has not been explored sufficiently in order to create attractive street-front images, yet such interaction is essential to the way the cityscape and its character are perceived by the eye. However, current insight regarding the sustainable New Town paradigm has brought a renewed perspective regarding design policy of the pedestrian precinct. This study investigates the formal features of the sequential street-front image of Dutch late-medieval town examples which could help re-formulate the existing design policies regarding the quality of pedestrian space especially in the artificial reclaimed land design field. The purpose is to find out how the principles of those old high-density artificial environmental design models generate such effective interaction between mobility and land usage, creating an enriched aesthetic visual image of street-front space as a result. PMID:15684563
NASA Technical Reports Server (NTRS)
Romanou, A.; Gregg, Watson W.; Romanski, J.; Kelley, M.; Bleck, R.; Healy, R.; Nazarenko, L.; Russell, G.; Schmidt, G. A.; Sun, S.; Tausnev, N.
2013-01-01
Results from twin control simulations of the preindustrial CO2 gas exchange (natural flux of CO2) between the ocean and the atmosphere are presented here using the NASA-GISS climate model, in which the same atmospheric component (modelE2) is coupled to two different ocean models, the Russell ocean model and HYCOM. Both incarnations of the GISS climate model are also coupled to the same ocean biogeochemistry module (NOBM) which estimates prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2. Model intercomparison is carried out at equilibrium conditions and model differences are contrasted with biases from present day climatologies. Although the models agree on the spatial patterns of the air-sea flux of CO2, they disagree on the strength of the North Atlantic and Southern Ocean sinks mainly because of kinematic (winds) and chemistry (pCO2) differences rather than thermodynamic (SST) ones. Biology/chemistry dissimilarities in the models stem from the different parameterizations of advective and diffusive processes, such as overturning, mixing and horizontal tracer advection and to a lesser degree from parameterizations of biogeochemical processes such as gravitational settling and sinking. The global meridional overturning circulation illustrates much of the different behavior of the biological pump in the two models, together with differences in mixed layer depth which are responsible for different SST, DIC and nutrient distributions in the two models and consequently different atmospheric feedbacks (in the wind, net heat and freshwater fluxes into the ocean).
Wang, Wei
2015-01-01
It is well recognized that protein product development is far more challenging than that for small-molecule drugs. The major challenges include inherent sensitivity to different types of stresses during the drug product manufacturing process, high rate of physical and chemical degradation during long-term storage, and enhanced aggregation and/or viscosity at high protein concentrations. In the past decade, many novel formulation concepts and technologies have been or are being developed to address these product development challenges for proteins. These concepts and technologies include use of uncommon/combination of formulation stabilizers, conjugation or fusion with potential stabilizers, site-specific mutagenesis, and preparation of nontraditional types of dosage forms—semiaqueous solutions, nonfreeze-dried solid formulations, suspensions, and other emerging concepts. No one technology appears to be mature, ideal, and/or adequate to address all the challenges. These gaps will likely remain in the foreseeable future and need significant efforts for ultimate resolution. PMID:25858529
Granulated decontamination formulations
Tucker, Mark D.
2007-10-02
A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a sorbent additive, and water. A highly adsorbent sorbent additive (e.g., amorphous silica, sorbitol, mannitol, etc.) is used to "dry out" one or more liquid ingredients into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field.
Peterson, S.R.; Felmy, A.R.; Serne, R.J.; Gee, G.W.
1983-08-01
An equilibrium thermodynamic conceptual model consisting of minerals and solid phases was developed to represent a soil column. A computer program was used as a tool to solve the system of mathematical equations imposed by the conceptual chemical model. The combined conceptual model and computer program were used to predict aqueous phase compositions of effluent solutions from permeability cells packed with geologic materials and percolated with uranium mill tailings solutions. Initial calculations of ion speciation and mineral solubility and our understanding of the chemical processes occurring in the modeled system were used to select solid phases for inclusion in the conceptual model. The modeling predictions were compared to the analytically determined column effluent concentrations. Hypotheses were formed, based on modeling predictions and laboratory evaluations, as to the probable mechanisms controlling the migration of selected contaminants. An assemblage of minerals and other solid phases could be used to predict the concentrations of several of the macro constituents (e.g., Ca, SO/sub 4/, Al, Fe, and Mn) but could not be used to predict trace element concentrations. These modeling conclusions are applicable to situations where uranium mill tailings solutions of low pH and high total dissolved solids encounter either clay liners or natural geologic materials that contain inherent acid neutralizing capacities. 116 references, 22 figures, 6 tables.
NASA Astrophysics Data System (ADS)
Shaffer, G.
2014-03-01
The Dcess Antarctic Ice Sheet (DAIS) model is presented. Model hindcasts of Antarctic Ice Sheet (AIS) sea level equivalent are forced by reconstructed Antarctic temperatures, global mean sea level and high-latitude, subsurface ocean temperatures, the latter calculated using the Danish Center for Earth System Science (DCESS) Earth System Model forced by reconstructed global mean atmospheric temperatures. The model is calibrated by comparing such hindcasts for different model configurations with paleoreconstructions of AIS sea level equivalent from the last interglacial, the last glacial maximum and the mid-Holocene. The calibrated model is then validated against present estimates of the rate of AIS ice loss. It is found that a high-order dependency of ice flow at the grounding line on water depth there is needed to capture the observed response of the AIS at ice age terminations. Furthermore it is found that a dependency of this ice flow on ocean subsurface temperature by way of ice shelf demise and a resulting buttressing decrease is needed to explain the contribution of the AIS to global mean sea level rise at the last interglacial. When forced and calibrated in this way, model hindcasts of the rate of present day AIS ice loss agree with recent, data-based estimates of this ice loss rate.
NASA Astrophysics Data System (ADS)
Shaffer, G.
2014-08-01
The DCESS (Danish Center for Earth System Science) Antarctic Ice Sheet (DAIS) model is presented. Model hindcasts of Antarctic ice sheet (AIS) sea level equivalent are forced by reconstructed Antarctic temperatures, global mean sea level and high-latitude, ocean subsurface temperatures, the latter calculated using the DCESS model forced by reconstructed global mean atmospheric temperatures. The model is calibrated by comparing such hindcasts for different model configurations with paleoreconstructions of AIS sea level equivalent from the last interglacial, the last glacial maximum and the mid-Holocene. The calibrated model is then validated against present estimates of the rate of AIS ice loss. It is found that a high-order dependency of ice flow at the grounding line on water depth there is needed to capture the observed response of the AIS at ice age terminations. Furthermore, it is found that a dependency of this ice flow on ocean subsurface temperature by way of ice shelf demise and a resulting buttressing decrease is needed to explain the contribution of the AIS to global mean sea level rise at the last interglacial. When forced and calibrated in this way, model hindcasts of the rate of present-day AIS ice loss agree with recent, data-based estimates of this ice loss rate.
NASA Astrophysics Data System (ADS)
Salamanca, Francisco; Krpo, Andrea; Martilli, Alberto; Clappier, Alain
2009-05-01
The generation of heat in buildings, and the way this heat is exchanged with the exterior, plays an important role in urban climate. To analyze the impact on urban climate of a change in the urban structure, it is necessary to build and use a model capable of accounting for all the urban heat fluxes. In this contribution, a new building energy model (BEM) is developed and implemented in an urban canopy parameterization (UCP) for mesoscale models. The new model accounts for: the diffusion of heat through walls, roofs, and floors; natural ventilation; the radiation exchanged between indoor surfaces; the generation of heat due to occupants and equipments; and the consumption of energy due to air conditioning systems. The behavior of BEM is compared to other models used in the thermal analysis of buildings (CBS-MASS, BLAST, and TARP) and with another box-building model. Eventually, a sensitivity analysis of different parameters, as well as a study of the impact of BEM on the UCP is carried out. The validations indicate that BEM provides good estimates of the physical behavior of buildings and it is a step towards a modeling tool that can be an important support to urban planners.
Super-Group Field Cosmology in Batalin-Vilkovisky Formulation
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker
2016-04-01
In this paper we study the third quantized super-group field cosmology, a model in multiverse scenario, in Batalin-Vilkovisky (BV) formulation. Further, we propose the superfield/super-antifield dependent BRST symmetry transformations. Within this formulation we establish connection between the two different solutions of the quantum master equation within the BV formulation.
Super-Group Field Cosmology in Batalin-Vilkovisky Formulation
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker
2016-09-01
In this paper we study the third quantized super-group field cosmology, a model in multiverse scenario, in Batalin-Vilkovisky (BV) formulation. Further, we propose the superfield/super-antifield dependent BRST symmetry transformations. Within this formulation we establish connection between the two different solutions of the quantum master equation within the BV formulation.
NASA Astrophysics Data System (ADS)
Maronga, B.; Gryschka, M.; Heinze, R.; Hoffmann, F.; Kanani-Sühring, F.; Keck, M.; Ketelsen, K.; Letzel, M. O.; Sühring, M.; Raasch, S.
2015-02-01
In this paper we present the current version of the Parallelized Large-Eddy Simulation Model (PALM) whose core has been developed at the Institute of Meteorology and Climatology at Leibniz Universität Hannover (Germany). PALM is a Fortran 95-based code with some Fortran 2003 extensions and has been applied for the simulation of a variety of atmospheric and oceanic boundary layers for more than 15 years. PALM is optimized for use on massively parallel computer architectures and was recently ported to general-purpose graphics processing units. In the present paper we give a detailed description of the current version of the model and its features, such as an embedded Lagrangian cloud model and the possibility to use Cartesian topography. Moreover, we discuss recent model developments and future perspectives for LES applications.
NASA Astrophysics Data System (ADS)
Maronga, B.; Gryschka, M.; Heinze, R.; Hoffmann, F.; Kanani-Sühring, F.; Keck, M.; Ketelsen, K.; Letzel, M. O.; Sühring, M.; Raasch, S.
2015-08-01
In this paper we present the current version of the Parallelized Large-Eddy Simulation Model (PALM) whose core has been developed at the Institute of Meteorology and Climatology at Leibniz Universität Hannover (Germany). PALM is a Fortran 95-based code with some Fortran 2003 extensions and has been applied for the simulation of a variety of atmospheric and oceanic boundary layers for more than 15 years. PALM is optimized for use on massively parallel computer architectures and was recently ported to general-purpose graphics processing units. In the present paper we give a detailed description of the current version of the model and its features, such as an embedded Lagrangian cloud model and the possibility to use Cartesian topography. Moreover, we discuss recent model developments and future perspectives for LES applications.
Lane, M E; Hadgraft, J; Oliveira, G; Vieira, R; Mohammed, D; Hirata, K
2012-12-01
To be efficacious and to satisfy the requirements for claim substantiation, a cosmetic formulation must achieve effective targeting of an active in the skin. Although the basic principles governing the skin permeation and disposition of molecules have been known for many years, attention has been far less focused on the role of the vehicle, particularly at cosmetically relevant doses. In this article, we discuss the necessity to understand the fate of the formulation components as well as the active once applied onto skin. Recent data confirm that the residence time of the formulation constituents can have a profound impact on the fate of the active. Approaches to identify the ideal vehicle for skin delivery are considered critically, specifically the recent work on 'formulating for efficacy' (FFE) by the late Johann Wiechers. Essentially, FFE aims to match the active with the optimal vehicle for skin delivery based on matching polarity/solubility values of the trinity of skin, active and vehicle. The emerging importance of techniques that provide insight to how the vehicle distributes in and on skin is highlighted. PMID:22882873
Payloads minimum EIRP formulations
NASA Technical Reports Server (NTRS)
1980-01-01
The effective isotropic radiated power (EIRP) of the payloads is formulated. The EIRP consists of three components; EIRP = P sub T + G sub T + L sub TX, where P sub T is the transmitter total RF output power, G sub T is the transmitting antenna gain, and L sub TX is all transmitter circuit losses.
Technology Transfer Automated Retrieval System (TEKTRAN)
Formulation development is one of many steps required for commercialization of biological pesticides and holds the promise to bridge the gap between production of the active agent and use by consumers. A biological pesticide begins with discovery of an agent capable of controlling a pest. Active a...
Hu, Bo; Sun, Ding; Sun, Chao; Sun, Yun-Fan; Sun, Hai-Xiang; Zhu, Qing-Feng; Yang, Xin-Rong; Gao, Ya-Bo; Tang, Wei-Guo; Fan, Jia; Maitra, Anirban; Anders, Robert A; Xu, Yang
2015-12-25
Curcumin, a yellow polyphenol extracted from the rhizome of turmeric root (Curcuma longa) has potent anti-cancer properties in many types of tumors with ability to reverse multidrug resistance of cancer cells. However, widespread clinical application of this agent in cancer and other diseases has been limited due to its poor aqueous solubility. The recent findings of polymeric nanoparticle formulation of curcumin (NFC) have shown the potential for circumventing the problem of poor solubility, however evidences for NFC's anti-cancer and reverse multidrug resistance properties are lacking. Here we provide models of human hepatocellular carcinoma (HCC), the most common form of primary liver cancer, in vitro and in vivo to evaluate the efficacy of NFC alone and in combination with sorafenib, a kinase inhibitor approved for treatment of HCC. Results showed that NFC not only inhibited the proliferation and invasion of HCC cell lines in vitro, but also drastically suppressed primary tumor growth and lung metastases in vivo. Moreover, in combination with sorafenib, NFC induced HCC cell apoptosis and cell cycle arrest. Mechanistically, NFC and sorafenib synergistically down-regulated the expression of MMP9 via NF-κB/p65 signaling pathway. Furthermore, the combination therapy significantly decreased the population of CD133-positive HCC cells, which have been reported as cancer initiating cells in HCC. Taken together, NanoCurcumin provides an opportunity to expand the clinical repertoire of this agent. Additional studies utilizing a combination of NanoCurcumin and sorafenib in HCC are needed for further clinical development. PMID:26482853
Pauli-Bruns, Anette; Knop, Klaus; Lippold, Bernhard C
2010-03-01
The one-step preparation of sustained release matrix pellets, using a melting procedure in a fluidized bed apparatus, was tested in a 2(3) full factorial design of experiments, using microcrystalline wax as lipophilic binder, theophylline as model drug and talc as additional matrix forming agent. The three influence parameters were (A) size of binder particles, (B) fraction of theophylline in solid particles and (C) fraction of microcrystalline wax in formulation. The response variables were agglomerate size and size distribution, dissolution time, agglomerate crush resistance, sphericity, yield and porosity. Nearly spherical pellets comprising a smooth, closed surface could be obtained with the used method, exhibiting the hollow core typical for the immersion and layering mechanism. The reproducibility was very good concerning all responses. The size of agglomerates is proportional to the size of the binder particles, which serve as cores for pellet formation in the molten state in the fluidized bed. Additionally, the agglomerate size is influenced by the volume of the solid particles in relation to the binder particles, with more solid particles leading to larger agglomerates and vice versa. Dissolution times vary in a very wide range, resulting from the interplay between amount of drug in relation to the meltable matrix substance microcrystalline wax and the non-meltable matrix substance talc. The change of binder particle size does not lead to a structural change of the matrix; both dissolution times and porosity are not significantly altered. Agglomerate crush resistance is low due to the hollow core of the pellets. However, it is significantly increased if the volume fraction of microcrystalline wax in the matrix is high, which means that the matrix is mechanically better stabilized. A theoretical model has been established to quantitatively explain agglomerate growth and very good accordance of the full particle size distributions between predicted and
NASA Technical Reports Server (NTRS)
Li, Yong; Moorthi, S.; Bates, J. Ray; Suarez, Max J.
1994-01-01
High order horizontal diffusion of the form K Delta(exp 2m) is widely used in spectral models as a means of preventing energy accumulation at the shortest resolved scales. In the spectral context, an implicit formation of such diffusion is trivial to implement. The present note describes an efficient method of implementing implicit high order diffusion in global finite difference models. The method expresses the high order diffusion equation as a sequence of equations involving Delta(exp 2). The solution is obtained by combining fast Fourier transforms in longitude with a finite difference solver for the second order ordinary differential equation in latitude. The implicit diffusion routine is suitable for use in any finite difference global model that uses a regular latitude/longitude grid. The absence of a restriction on the timestep makes it particularly suitable for use in semi-Lagrangian models. The scale selectivity of the high order diffusion gives it an advantage over the uncentering method that has been used to control computational noise in two-time-level semi-Lagrangian models.
A mixed formulation for elastic multilayer plates
NASA Astrophysics Data System (ADS)
Fernandes, Amâncio
2003-05-01
A new approach based on a mixed formulation is proposed. The main advantage of such a formulation is that the transverse shear stress continuity is automatically satisfied in a natural way. In order to validate the model, comparisons of the proposed theory to Pagano's exact elasticity solutions are made for a bi-layer and a sandwich plate. To cite this article: A. Fernandes, C. R. Mecanique 331 (2003).
Van Regenmortel, Tina; Janssen, Colin R; De Schamphelaere, Karel A C
2015-07-01
Although it is increasingly recognized that biotic ligand models (BLMs) are valuable in the risk assessment of metals in aquatic systems, the use of 2 differently structured and parameterized BLMs (1 in the United States and another in the European Union) to obtain bioavailability-based chronic water quality criteria for copper is worthy of further investigation. In the present study, the authors evaluated the predictive capacity of these 2 BLMs for a large dataset of chronic copper toxicity data with 2 Daphnia magna clones, termed K6 and ARO. One BLM performed best with clone K6 data, whereas the other performed best with clone ARO data. In addition, there was an important difference between the 2 BLMs in how they predicted the bioavailability of copper as a function of pH. These modeling results suggested that the effect of pH on chronic copper toxicity is different between the 2 clones considered, which was confirmed with additional chronic toxicity experiments. Finally, because fundamental differences in model structure between the 2 BLMs made it impossible to create an average BLM, a generalized bioavailability model (gBAM) was developed. Of the 3 gBAMs developed, the authors recommend the use of model gBAM-C(uni), which combines a log-linear relation between the 21-d median effective concentration (expressed as free Cu(2+) ion activity) and pH, with more conventional BLM-type competition constants for sodium, calcium, and magnesium. This model can be considered a first step in further improving the accuracy of chronic toxicity predictions of copper as a function of water chemistry (for a variety of Daphnia magna clones), even beyond the robustness of the current BLMs used in regulatory applications. PMID:25771778
Clark, Simon; Cross, Martin L; Smith, Alan; Court, Pinar; Vipond, Julia; Nadian, Allan; Hewinson, R Glyn; Batchelor, Hannah K; Perrie, Yvonne; Williams, Ann; Aldwell, Frank E; Chambers, Mark A
2008-10-29
Bovine tuberculosis (bTB) caused by infection with Mycobacterium bovis is causing considerable economic loss to farmers and Government in the United Kingdom as its incidence is increasing. Efforts to control bTB in the UK are hampered by the infection in Eurasian badgers (Meles meles) that represent a wildlife reservoir and source of recurrent M. bovis exposure to cattle. Vaccination of badgers with the human TB vaccine, M. bovis Bacille Calmette-Guérin (BCG), in oral bait represents a possible disease control tool and holds the best prospect for reaching badger populations over a wide geographical area. Using mouse and guinea pig models, we evaluated the immunogenicity and protective efficacy, respectively, of candidate badger oral vaccines based on formulation of BCG in lipid matrix, alginate beads, or a novel microcapsular hybrid of both lipid and alginate. Two different oral doses of BCG were evaluated in each formulation for their protective efficacy in guinea pigs, while a single dose was evaluated in mice. In mice, significant immune responses (based on lymphocyte proliferation and expression of IFN-gamma) were only seen with the lipid matrix and the lipid in alginate microcapsular formulation, corresponding to the isolation of viable BCG from alimentary tract lymph nodes. In guinea pigs, only BCG formulated in lipid matrix conferred protection to the spleen and lungs following aerosol route challenge with M. bovis. Protection was seen with delivery doses in the range 10(6)-10(7) CFU, although this was more consistent in the spleen at the higher dose. No protection in terms of organ CFU was seen with BCG administered in alginate beads or in lipid in alginate microcapsules, although 10(7) in the latter formulation conferred protection in terms of increasing body weight after challenge and a smaller lung to body weight ratio at necropsy. These results highlight the potential for lipid, rather than alginate, -based vaccine formulations as suitable delivery
Equivalence of Dirac formulations
NASA Astrophysics Data System (ADS)
Joyce, William P.; Martin, Jeremy G.
2002-06-01
We construct general Dirac theories in both ⊗ ℓ(3, 1) and ⊗ ℓ(1, 3) using a first order left acting Dirac operator. Any two such theories are equivalent provided they have the same dimension. We also show that every 16- or 8-dimensional real Dirac theory in ℓ(3, 1) is equivalent to some (complex) Dirac theory in ⊗ ℓ(1, 3). As an immediate consequence of this we have that the Hestenes and original Dirac formulations are equivalent.
Liposomal formulations for inhalation.
Cipolla, David; Gonda, Igor; Chan, Hak-Kim
2013-08-01
No marketed inhaled products currently use sustained release formulations such as liposomes to enhance drug disposition in the lung, but that may soon change. This review focuses on the interaction between liposomal formulations and the inhalation technology used to deliver them as aerosols. There have been a number of dated reviews evaluating nebulization of liposomes. While the information they shared is still accurate, this paper incorporates data from more recent publications to review the factors that affect aerosol performance. Recent reviews have comprehensively covered the development of dry powder liposomes for aerosolization and only the key aspects of those technologies will be summarized. There are now at least two inhaled liposomal products in late-stage clinical development: ARIKACE(®) (Insmed, NJ, USA), a liposomal amikacin, and Pulmaquin™ (Aradigm Corp., CA, USA), a liposomal ciprofloxacin, both of which treat a variety of patient populations with lung infections. This review also highlights the safety of inhaled liposomes and summarizes the clinical experience with liposomal formulations for pulmonary application. PMID:23919478
Chetty, Manoranjenni; Rose, Rachel H.; Abduljalil, Khaled; Patel, Nikunjkumar; Lu, Gaohua; Cain, Theresa; Jamei, Masoud; Rostami-Hodjegan, Amin
2014-01-01
This study aimed to demonstrate the added value of integrating prior in vitro data and knowledge-rich physiologically based pharmacokinetic (PBPK) models with pharmacodynamics (PDs) models. Four distinct applications that were developed and tested are presented here. PBPK models were developed for metoprolol using different CYP2D6 genotypes based on in vitro data. Application of the models for prediction of phenotypic differences in the pharmacokinetics (PKs) and PD compared favorably with clinical data, demonstrating that these differences can be predicted prior to the availability of such data from clinical trials. In the second case, PK and PD data for an immediate release formulation of nifedipine together with in vitro dissolution data for a controlled release (CR) formulation were used to predict the PK and PD of the CR. This approach can be useful to pharmaceutical scientists during formulation development. The operational model of agonism was used in the third application to describe the hypnotic effects of triazolam, and this was successfully extrapolated to zolpidem by changing only the drug related parameters from in vitro experiments. This PBPK modeling approach can be useful to developmental scientists who which to compare several drug candidates in the same therapeutic class. Finally, differences in QTc prolongation due to quinidine in Caucasian and Korean females were successfully predicted by the model using free heart concentrations as an input to the PD models. This PBPK linked PD model was used to demonstrate a higher sensitivity to free heart concentrations of quinidine in Caucasian females, thereby providing a mechanistic understanding of a clinical observation. In general, permutations of certain conditions which potentially change PK and hence PD may not be amenable to the conduct of clinical studies but linking PBPK with PD provides an alternative method of investigating the potential impact of PK changes on PD. PMID:25505415
Potential formulation of sleep dynamics
NASA Astrophysics Data System (ADS)
Phillips, A. J. K.; Robinson, P. A.
2009-02-01
A physiologically based model of the mechanisms that control the human sleep-wake cycle is formulated in terms of an equivalent nonconservative mechanical potential. The potential is analytically simplified and reduced to a quartic two-well potential, matching the bifurcation structure of the original model. This yields a dynamics-based model that is analytically simpler and has fewer parameters than the original model, allowing easier fitting to experimental data. This model is first demonstrated to semiquantitatively match the dynamics of the physiologically based model from which it is derived, and is then fitted directly to a set of experimentally derived criteria. These criteria place rigorous constraints on the parameter values, and within these constraints the model is shown to reproduce normal sleep-wake dynamics and recovery from sleep deprivation. Furthermore, this approach enables insights into the dynamics by direct analogies to phenomena in well studied mechanical systems. These include the relation between friction in the mechanical system and the timecourse of neurotransmitter action, and the possible relation between stochastic resonance and napping behavior. The model derived here also serves as a platform for future investigations of sleep-wake phenomena from a dynamical perspective.
Formulations of entomopathogens as bioinsecticides
Technology Transfer Automated Retrieval System (TEKTRAN)
Developing a proper formulation is a necessary component for commercialization of entomopathogenic microbes as biological insecticides. The objective of this chapter is to present broad-ranging information about formulations to foster research toward developing commercial microbial-based insecticide...
Monajjemzadeh, Farnaz; Ebrahimi, Fatemeh; Zakeri-Milani, Parvin; Valizadeh, Hadi
2014-01-01
Purpose: In this research the effect of vitamin B1 and B6 on cyanocobalamin stability in commercial light protected parenteral formulations and upon adding stabilizing agents will be investigated and best formulation composition and proper storage condition will be introduced. Methods: In this research some additives such as co solvents and tonicity adjusters, surfactants, antioxidants and chelating agents as well as buffer solutions, were used to improve the stability of the parenteral mixed formulations of B12 in the presence of other B vitamins (B1 and B6). Screening tests and accelerated stability tests were performed according to ICH guidelines Q1A (R2). Results: Shelf life evaluation revealed the best formulation and the proper storage condition. The results indicated the first kinetic models for all tested formulations and the optimum pH value was determined to be 5.8. There was no evidence of B12 loss when mixed with B1 and B6 in a medical syringe at room temperature for maximum of 8 hours. Conclusion: It is necessary to formulate vitamin B12 mixed parenteral solutions using proper phosphate buffers (pH=5.8) and to indicate “Store in refrigerator” on the mixed parenteral formulations of vitamin B12 with other B vitamins, which has not been expressed on the label of tested Brand formulations at the time of this study. PMID:25436187
Formal descriptions for formulation.
This, Hervé
2007-11-01
Two formalisms used to describe the physical microstructure and the organization of formulated products are given. The first, called "complex disperse systems formalism" (CDS formalism) is useful for the description of the physical nature of disperse matter. The second, called "non periodical organizational space formalism" (NPOS formalism) has the same operators as the CDS formalism, but different elements; it is useful to describe the arrangement of any objects in space. Both formalisms can be viewed as the same, applied to different orders of magnitude for spatial size. PMID:17875375
Stability of Sulforaphane for Topical Formulation
Franklin, Stephen J.; Dickinson, Sally E.; Karlage, Kelly L.; Bowden, G Tim.; Myrdal, Paul B.
2013-01-01
Sulforaphane (SFN) is a natural compound that has been investigated as a chemopreventive agent. SFN has been shown to inhibit the activator-protein-1 (AP-1) transcription factor and may be effective for inhibition of ultraviolet (UV) induced skin carcinogenesis. This study was designed to investigate the stability of SFN as a function of pH, temperature and in various solvents and formulations. SFN was determined to undergo apparent first order degradation kinetics for the conditions explored. It was observed that SFN undergoes base catalyzed degradation. Buffer species and solvent type impacts stability as well. SFN was found to be very sensitive to temperature with degradation rate changing by a factor of nearly 3.1 for every 10°C change in temperature (at pH 4.0). SFN completely degraded after 30 days in a conventional pharmaceutical cream formulation. Improved stability was observed in organic formulation components. Stability studies were conducted on two non-aqueous topical formulations, a polyethylene glycol (PEG) ointment base and an organic oleaginous base. Topically applied SFN in the PEG base formulation significantly reduced AP-1 activation after UV stimulation in the skin of a transgenic mouse model, indicating that SFN in this formulation retains efficacy in vivo. PMID:23611476
Rapid pharmacokinetic evaluation of topical drug formulations.
Garzouzi, V L
1999-01-01
A new in vitro test system was developed to efficiently determine the effect of formulation on topical drug delivery. Sheets of viable, excised pig skin were sandwiched betwween two standard 24-well plates. The lower wells contained receptor fluid and a magnetic stirrer. The upper wells were opened to the atmosphere for formulation application. Using 14C-salicylic acid as a model compound, eight different formulations were evaluated representing hydrophilic and lipophilic solutions, a suspension and o/w and w/o emulsions. Formulations were applied to the skin surface in six different wells on three sets of plates. Twenty-four hours after application, excess drug was wiped from the skin surface and assayed for radiolabel. The stratum corneum was removed by tape stripping. Radiolabel contained in the remaining epidermis, dermis and receptor fluid was also determined. Statistical analysis (ANOVA, Student-Newman-Keuls multiple-range test, p=0.05) of radiolabel penetrating into the dermis and receptor fluid revealed the following order of formulations: ethanol= aqueous surfactant less than o/w emulsion = w/o emulsion less than lipophilic solution. These results demonstrate the importance of vehicle in directing drug delivery using a test system capable of simultaneously evaluating a large number of formulations. PMID:23985716
Antiinflammatory activity of a polyherbal formulation.
Deorukhakar, S R; Dethe, A; Vohra, R R; Ghosh, R; Chaudhary, J; Kadam, V
2008-11-01
The antiinflammatory activity of the polyherbal formulation Entox(®) was investigated in rats for acute and sub acute models of inflammation using carrageenan-induced rat paw edema and cotton pellet granuloma methods respectively at a dose of 300 mg/kg and 600 mg/kg administered orally. The formulation in doses of 300 mg/kg and 600 mg/kg showed 51.61% and 54.84% inhibition of paw edema, respectively at the end of 3 h. The percent inhibition of granuloma by cotton pellet method was 27.92% and 53.17%, respectively. The formulation showed a significant antiinflammatory activity in both the experimental models and the activity was comparable to that of the standard drug, indomethacin. PMID:21369442
Nanoliposomal Dry Powder Formulations
Patel, Gaurang; Chougule, Mahavir; Singh, Mandip; Misra, Ambikanandan
2013-01-01
Liposomal dry powder formulations (DPFs) have proven their superiority over conventional DPFs due to favorably improved pharmacokinetics and pharmacodynamics of entrapped drugs, and thus, reduced local and systemic toxicities. Nanoliposomal DPFs (NLDPFs) provide stable, high aerosolization efficiency to deep lung, prolonged drug release, slow systemic dilution, and avoid macrophage uptake of encapsulated drug by carrier-based delivery of nano-range liposomes. This chapter describes methods of preparation of nanoliposomes (NLs) and NLDPFs, using various techniques, and their characterization with respect to size distribution, flow behavior, in vitro drug release profile, lung deposition, cellular uptake and cytotoxicity, and in vivo pharmacokinetics and pharmacodynamics. Some examples have been detailed for better understanding of the methods of preparation and evaluation of NLDPFs by investigators. PMID:19903555
Ferreira, Diêgo dos Santos; Faria, Samilla Dornelas; Lopes, Sávia Caldeira de Araújo; Teixeira, Cláudia Salviano; Malachias, Angelo; Magalhães-Paniago, Rogério; de Souza Filho, José Dias; Oliveira, Bruno Luis de Jesus Pinto; Guimarães, Alexander Ramos; Caravan, Peter; Ferreira, Lucas Antônio Miranda; Alves, Ricardo José; Oliveira, Mônica Cristina
2016-01-01
Background Despite recent advances in cancer therapy, the treatment of bone tumors remains a major challenge. A possible underlying hypothesis, limitation, and unmet need may be the inability of therapeutics to penetrate into dense bone mineral, which can lead to poor efficacy and high toxicity, due to drug uptake in healthy organs. The development of nanostructured formulations with high affinity for bone could be an interesting approach to overcome these challenges. Purpose To develop a liposomal formulation with high affinity for hydroxyapatite and the ability to release doxorubicin (DOX) in an acidic environment for future application as a tool for treatment of bone metastases. Materials and methods Liposomes were prepared by thin-film lipid hydration, followed by extrusion and the sulfate gradient-encapsulation method. Liposomes were characterized by average diameter, ζ-potential, encapsulation percentage, X-ray diffraction, and differential scanning calorimetry. Release studies in buffer (pH 7.4 or 5), plasma, and serum, as well as hydroxyapatite-affinity in vitro analysis were performed. Cytotoxicity was evaluated by MTT assay against the MDA-MB-231 cell line, and biodistribution was assessed in bone metastasis-bearing animals. Results Liposomes presented suitable diameter (~170 nm), DOX encapsulation (~2 mg/mL), controlled release, and good plasma and serum stability. The existence of interactions between DOX and the lipid bilayer was proved through differential scanning calorimetry and small-angle X-ray scattering. DOX release was faster when the pH was in the range of a tumor than at physiological pH. The bone-targeted formulation showed a strong affinity for hydroxyapatite. The encapsulation of DOX did not interfere in its intrinsic cytotoxicity against the MDA-MB-231 cell line. Biodistribution studies demonstrated high affinity of this formulation for tumors and reduction of uptake in the heart. Conclusion These results suggest that bone-targeted p
Feeney, Orlagh M; Williams, Hywel D; Pouton, Colin W; Porter, Christopher J H
2014-10-28
For over 20years, stealth drug delivery has been synonymous with nanoparticulate formulations and intravenous dosing. The putative determinants of stealth in these applications are the molecular weight and packing density of a hydrophilic polymer (commonly poly(ethylene glycol) (PEG)) that forms a steric barrier at the surface of the nanoparticle. The current study examined the potential translation of the concepts learned from stealth technology after intravenous administration to oral drug delivery and specifically, to enhance drug exposure after administration of oral lipid-based formulations (LBFs) containing medium-chain triglycerides (MCT). MCT LBFs are rapidly digested in the gastrointestinal tract, typically resulting in losses in solubilisation capacity, supersaturation and drug precipitation. Here, non-ionic surfactants containing stealth PEG headgroups were incorporated into MCT LBFs in an attempt to attenuate digestion, reduce precipitation risk and enhance drug exposure. Stealth capabilities were assessed by measuring the degree of digestion inhibition that resulted from steric hindrance of enzyme access to the oil-water interface. Drug-loaded LBFs were assessed for maintenance of solubilising capacity during in vitro digestion and evaluated in vivo in rats. The data suggest that the structural determinants of stealth LBFs mirror those of parenteral formulations, i.e., the key factors are the molecular weight of the PEG in the surfactant headgroup and the packing density of the PEG chains at the interface. Interestingly, the data also show that the presence of labile ester bonds within a PEGylated surfactant also impact on the stealth properties of LBFs, with digestible surfactants requiring a PEG Mw of ~1800g/mol and non-digestible ether-based surfactants ~800g/mol to shield the lipidic cargo. In vitro evaluation of drug solubilisation during digestion showed stealth LBFs maintained drug solubilisation at or above 80% of drug load and reduced
NASA Astrophysics Data System (ADS)
Agrawal, Vaibhav; Dayal, Kaushik
2015-12-01
The motion of microstructural interfaces is important in modeling twinning and structural phase transformations. Continuum models fall into two classes: sharp-interface models, where interfaces are singular surfaces; and regularized-interface models, such as phase-field models, where interfaces are smeared out. The former are challenging for numerical solutions because the interfaces need to be explicitly tracked, but have the advantage that the kinetics of existing interfaces and the nucleation of new interfaces can be transparently and precisely prescribed. In contrast, phase-field models do not require explicit tracking of interfaces, thereby enabling relatively simple numerical calculations, but the specification of kinetics and nucleation is both restrictive and extremely opaque. This prevents straightforward calibration of phase-field models to experiment and/or molecular simulations, and breaks the multiscale hierarchy of passing information from atomic to continuum. Consequently, phase-field models cannot be confidently used in dynamic settings. This shortcoming of existing phase-field models motivates our work. We present the formulation of a phase-field model - i.e., a model with regularized interfaces that do not require explicit numerical tracking - that allows for easy and transparent prescription of complex interface kinetics and nucleation. The key ingredients are a re-parametrization of the energy density to clearly separate nucleation from kinetics; and an evolution law that comes from a conservation statement for interfaces. This enables clear prescription of nucleation - through the source term of the conservation law - and kinetics - through a distinct interfacial velocity field. A formal limit of the kinetic driving force recovers the classical continuum sharp-interface driving force, providing confidence in both the re-parametrized energy and the evolution statement. We present some 1D calculations characterizing the formulation; in a
Boson formulation of fermion field theories
Ha, Y.K.
1984-04-15
The nonperturbative connection between a canonical Fermi field and a canonical Bose field in two dimensions is developed and its validity verified according to the tenets of quantum field theory. We advocate the point of view that a boson formulation offers a unifying theme in understanding the structure of many theories. This is illustrated by the boson formulation of a multifermion theory with chiral and internal symmetries. Many features of the massless theory, such as dynamical mass generation with asymptotic-freedom behavior, hidden chiral symmetry, and connections with models of apparently different internal symmetries, are readily transparent through such fermion-boson metamorphosis.
Colina-Márquez, José; Machuca-Martínez, Fiderman; Li Puma, Gianluca
2015-01-01
Endocrine disruptors in water are contaminants of emerging concern due to the potential risks they pose to the environment and to the aquatic ecosystems. In this study, a solar photocatalytic treatment process in a pilot-scale compound parabolic collector (CPC) was used to remove commercial estradiol formulations (17-β estradiol and nomegestrol acetate) from water. Photolysis alone degraded up to 50% of estradiol and removed 11% of the total organic carbon (TOC). In contrast, solar photocatalysis degraded up to 57% of estrogens and the TOC removal was 31%, with 0.6 g/L of catalyst load (TiO2 Aeroxide P-25) and 213.6 ppm of TOC as initial concentration of the commercial estradiols formulation. The adsorption of estrogens over the catalyst was insignificant and was modeled by the Langmuir isotherm. The TOC removal via photocatalysis in the photoreactor was modeled considering the reactor fluid-dynamics, the radiation field, the estrogens mass balance, and a modified Langmuir-Hinshelwood rate law, that was expressed in terms of the rate of photon adsorption. The optimum removal of the estrogens and TOC was achieved at a catalyst concentration of 0.4 g/L in 29 mm diameter tubular CPC reactors which approached the optimum catalyst concentration and optical thickness determined from the modeling of the absorption of solar radiation in the CPC, by the six-flux absorption-scattering model (SFM). PMID:26205059
NASA Astrophysics Data System (ADS)
Cammalleri, C.; Anderson, M. C.; Ciraolo, G.; D'Urso, G.; Kustas, W. P.; La Loggia, G.; Minacapilli, M.
2010-07-01
For open orchard and vineyard canopies containing significant fractions of exposed soil (>50%), typical of Mediterranean agricultural regions, the energy balance of the vegetation elements is strongly influenced by heat exchange with the bare soil/substrate. For these agricultural systems a "two-source" approach, where radiation and turbulent exchange between the soil and canopy elements are explicitly modelled, appears to be the only suitable methodology for reliably assessing energy fluxes. In strongly clumped canopies, the effective wind speed profile inside and below the canopy layer can highly influence the partitioning of energy fluxes between the soil and vegetation components. To assess the impact of in-canopy wind profile on model flux estimates, an analysis of three different formulations is presented, including algorithms from Goudriaan (1977), Massman (1987) and Lalic et al. (2003). The in-canopy wind profile formulations are applied to the thermal-based Two-Source Energy Balance (TSEB) model developed by Norman et al. (1995) and modified by Kustas and Norman (1999). High resolution airborne remote sensing images, collected over an agricultural area located in the western part of Sicily (Italy) comprised primarily of vineyards, olive and citrus orchards, are used to derive all the input parameters need to apply the TSEB. The images were acquired from June to October 2008 and include a relatively wide range of meteorological and soil moisture conditions. A preliminary sensitivity analysis of the three wind profile algorithms highlight the dependence of wind speed just above the soil/substrate to leaf area index and canopy height over the typical canopy properties range of these agricultural area. It is found that differences in wind just above surface among the models is most significant under sparse and medium fractional cover conditions (20-60%). The TSEB model heat flux estimates are compared with micrometeorological measurements from a small aperture
Plutonium Immobilization Project Baseline Formulation
Ebbinghaus, B.
1999-02-01
A key milestone for the Immobilization Project (AOP Milestone 3.2a) in Fiscal Year 1998 (FY98) is the definition of the baseline composition or formulation for the plutonium ceramic form. The baseline formulation for the plutonium ceramic product must be finalized before the repository- and plant-related process specifications can be determined. The baseline formulation that is currently specified is given in Table 1.1. In addition to the baseline formulation specification, this report provides specifications for two alternative formulations, related compositional specifications (e.g., precursor compositions and mixing recipes), and other preliminary form and process specifications that are linked to the baseline formulation. The preliminary specifications, when finalized, are not expected to vary tremendously from the preliminary values given.
Explosive Formulation Code Naming SOP
Martz, H. E.
2014-09-19
The purpose of this SOP is to provide a procedure for giving individual HME formulations code names. A code name for an individual HME formulation consists of an explosive family code, given by the classified guide, followed by a dash, -, and a number. If the formulation requires preparation such as packing or aging, these add additional groups of symbols to the X-ray specimen name.
Baseline LAW Glass Formulation Testing
Kruger, Albert A.; Mooers, Cavin; Bazemore, Gina; Pegg, Ian L.; Hight, Kenneth; Lai, Shan Tao; Buechele, Andrew; Rielley, Elizabeth; Gan, Hao; Muller, Isabelle S.; Cecil, Richard
2013-06-13
The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.
Abrol, Sonia; Trehan, Aman; Katare, Om Parkash
2005-01-01
The aim of the present study was to study the synergistic hepatoprotective effect of silymarin with phospholipids when it is encaged in microspheres so as to passively target it to liver and to compare these silymarin formulations with silymarin solution. Various silymarin loaded lipid emulsions were formulated which include formulation A prepared with soyabean oil as an internal oily phase, soya lecithin as surfactant and tween 80 as cosurfactant; formulation B which was same as formulation A but was filtered through 0.45 micro membrane filter and finally steam sterilized for intravenous administration; formulation C containing soyabean oil as an internal oily phase, soya lecithin as surfactant, tween 80 and propylene glycol as cosurfactant/ cosolvent. These formulations were compared for their release profile with silymarin solution in propylene glycol, i.e. formulation D. In vivo evaluation was carried out using three models i.e. phenobarbitone induced sleep time in mice, biochemical estimation of SGOT and SGPT enzyme levels and histopathological examination of rat livers. Results revealed that there was significant reduction in sleep time in the mice treated with silymarin loaded lipid microspheres (both p.o. as well as i.v.) when compared with control and even with plain lipid microspheres and silymarin solution and significant reduction in enzyme levels in silymarin lipid microspheres treated group when compared with control, plain lipid microspheres as well as silymarin solution treated group. Histopathological studies also supported the results obtained from the other two models. A positive outcome of these studies gave an insight that if silymarin is coupled with phospholipid in such microparticulate delivery systems, hepatoprotective effect of drug molecules can be pronounced further by self targeting nature and synergistic action. PMID:16305407
Evaluation of vaginal antifungal formulations in vivo.
McRipley, R. J.; Erhard, P. J.; Schwind, R. A.; Whitney, R. R.
1979-01-01
Relatively simple and rapid procedures have been developed for evaluating the local efficacy of vaginal antifungal agents in vivo in a vaginal candidiasis model in ovariectomized rats. The results of this investigation indicate that the model and methods described are quite suitable for screening potential antifungal substances and for assessing the chemotherapeutic effectiveness of new antifungal agents and formulations before carrying out clinical studies. PMID:392480
Saltstone Clean Cap Formulation
Langton, C
2005-04-22
The current operation strategy for using Saltstone Vault 4 to receive 0.2 Ci/gallon salt solution waste involves pouring a clean grout layer over the radioactive grout prior to initiating pour into another cell. This will minimize the radiating surface area and reduce the dose rate at the vault and surrounding area. The Clean Cap will be used to shield about four feet of Saltstone poured into a Z-Area vault cell prior to moving to another cell. The minimum thickness of the Clean Cap layer will be determined by the cesium concentration and resulting dose levels and it is expected to be about one foot thick based on current calculations for 0.1 Ci Saltstone that is produced in the Saltstone process by stabilization of 0.2 Ci salt solution. This report documents experiments performed to identify a formulation for the Clean Cap. Thermal transient calculations, adiabatic temperature rise measurements, pour height, time between pour calculations and shielding calculations were beyond the scope and time limitations of this study. However, data required for shielding calculations (composition and specific gravity) are provided for shielding calculations. The approach used to design a Clean Cap formulation was to produce a slurry from the reference premix (10/45/45 weight percent cement/slag/fly ash) and domestic water that resembled as closely as possible the properties of the Saltstone slurry. In addition, options were investigated that may offer advantages such as less bleed water and less heat generation. The options with less bleed water required addition of dispersants. The options with lower heat contained more fly ash and less slag. A mix containing 10/45/45 weight percent cement/slag/fly ash with a water to premix ratio of 0.60 is recommended for the Clean Cap. Although this mix may generate more than 3 volume percent standing water (bleed water), it has rheological, mixing and flow properties that are similar to previously processed Saltstone. The recommended
Operator Formulation of Classical Mechanics.
ERIC Educational Resources Information Center
Cohn, Jack
1980-01-01
Discusses the construction of an operator formulation of classical mechanics which is directly concerned with wave packets in configuration space and is more similar to that of convential quantum theory than other extant operator formulations of classical mechanics. (Author/HM)
Formulation of Higher Education Institutional Strategy Using Operational Research Approaches
ERIC Educational Resources Information Center
Labib, Ashraf; Read, Martin; Gladstone-Millar, Charlotte; Tonge, Richard; Smith, David
2014-01-01
In this paper a framework is proposed for the formulation of a higher education institutional (HEI) strategy. This work provides a practical example, through a case study, to demonstrate how the proposed framework can be applied to the issue of formulation of HEI strategy. The proposed hybrid model is based on two operational research…
Nanoparticle formulation of ormeloxifene for pancreatic cancer
Khan, Sheema; Chauhan, Neeraj; Yallapu, Murali M.; Ebeling, Mara C.; Balakrishna, Swathi; Ellis, Robert T.; Thompson, Paul A.; Balabathula, Pavan; Behrman, Stephen W.; Zafar, Nadeem; Singh, Man Mohan; Halaweish, Fathi T.; Jaggi, Meena; Chauhan, Subhash C.
2015-01-01
Pancreatic cancer is the fourth most prevalent cancer with about an 85% mortality rate; thus, an utmost need exists to discover new therapeutic modalities that would enhance therapy outcomes of this disease with minimal or no side effects. Ormeloxifene (ORM), a synthetic molecule, has exhibited potent anti-cancer effects through inhibition of important oncogenic and proliferation signaling pathways. However, the anti-cancer efficacy of ORM can be further improved by developing its nanoformulation, which will also offer tumor specific targeted delivery. Therefore, we have developed a novel ORM encapsulated poly(lactic-co-glycolic acid) nanoparticle (NP) formulation (PLGA-ORM NP). This formulation was characterized for particle size, chemical composition, and drug loading efficiency, using various physico-chemical methods (TEM, FT-IR, DSC, TGA, and HPLC). Because of its facile composition, this novel formulation is compatible with antibody/aptamer conjugation to achieve tumor specific targeting. The particle size analysis of this PLGA-ORM formulation (~ 100 nm) indicates that this formulation can preferentially reach and accumulate in tumors by the Enhanced Permeability and Retention (EPR) effect. Cellular uptake and internalization studies demonstrate that PLGA-ORM NPs escape lysosomal degradation, providing efficient endosomal release to cytosol. PLGA-ORM NPs showed remarkable anti-cancer potential in various pancreatic cancer cells (HPAF-II, BxPC-3, Panc-1, MiaPaca) and a BxPC-3 xenograft mice model resulting in increased animal survival. PLGA-ORM NPs suppressed pancreatic tumor growth via suppression of Akt phosphorylation and expression of MUC1, HER2, PCNA, CK19 and CD31. This study suggests that the PLGA-ORM formulation is highly efficient for the inhibition of pancreatic tumor growth and thus can be valuable for the treatment of pancreatic cancer in the future. PMID:25890768
Harbaugh, Arlen W.
1992-01-01
The U.S. Geological Survey's Modular Ground-Water Flow Model assumes that model nodes are in the center of cells and that transmissivity is constant within a cell. Based on these assumptions, the model calculates coefficients, called conductance, that are multiplied by head difference to determine flow between cells. Although these are common assumptions in finite-difference models, other assumptions are possible. A new option to the model program reads conductance as input data rather than calculating it. This optional lows the user to calculate conductance outside of the model. The user thus has the flexibility to define conductance using any desired assumptions. For a water-table condition, horizontal conductance must change as water level varies. To handle this situation, the new option reads conductance divided by thickness (CDT) as input data. The model calculates saturated thickness and multiplies it by CDT to obtain conductance. Thus, the user is still free from the assumptions of centered nodes and constant transmissivity in cells. The model option is written in FORTRAN77 and is fully compatible with the existing model. This report documents the new model option; it includes a description of the concepts, detailed input instructions, and a listing of the code.
Naval fuel saltstone formulation change
Harley, J.P. Jr.; Langton, C.A.
1987-10-19
Laboratory results support a formulation change for Naval Fuels saltstone from a cement-only waste form to a cement and Class F fly ash waste form. The recommended base formulation is waste, concentrated to a SpG of 1.35, mixed with a 1:1 ratio of Type 1 Portland cement and class F fly ash to achieve a water to cementitious materials (includes fly ash) ratio of 0.4. Due to variations in waste water chemistry, permit modifications should specify formulation ranges such that saltstone physical and chemical properties are enhanced. Operations should be based on pretesting each waste batch and adjusting the base formulation within specified ranges (ie. Draft DPSOL 247 WW-0312, ``Saltcrete Formulation Testing for Rapid Set and Excess Water.``) EP toxicity and TCLP tests are included and show comparable results for both cement-only and cement/fly ash waste forms. Heat generation due to hydration, a current problem with the cementonly formulation, is significantly reduced in the cement/fly ash mixture. In addition to the improved physical characteristics of the cement/fly ash formulation, savings of approximately 33% in raw materials cost may be obtained due to the substitution of the lower cost fly ash for cement in the Naval Fuels waste solidification process.
Naval fuel saltstone formulation change
Harley, J.P. Jr. and Co., Aiken, SC . Savannah River Plant); Langton, C.A. )
1987-10-19
Laboratory results support a formulation change for Naval Fuels saltstone from a cement-only waste form to a cement and Class F fly ash waste form. The recommended base formulation is waste, concentrated to a SpG of 1.35, mixed with a 1:1 ratio of Type 1 Portland cement and class F fly ash to achieve a water to cementitious materials (includes fly ash) ratio of 0.4. Due to variations in waste water chemistry, permit modifications should specify formulation ranges such that saltstone physical and chemical properties are enhanced. Operations should be based on pretesting each waste batch and adjusting the base formulation within specified ranges (ie. Draft DPSOL 247 WW-0312, Saltcrete Formulation Testing for Rapid Set and Excess Water.'') EP toxicity and TCLP tests are included and show comparable results for both cement-only and cement/fly ash waste forms. Heat generation due to hydration, a current problem with the cementonly formulation, is significantly reduced in the cement/fly ash mixture. In addition to the improved physical characteristics of the cement/fly ash formulation, savings of approximately 33% in raw materials cost may be obtained due to the substitution of the lower cost fly ash for cement in the Naval Fuels waste solidification process.
Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.
2013-03-01
Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.
Novel Formulations for Antimicrobial Peptides
Carmona-Ribeiro, Ana Maria; Carrasco, Letícia Dias de Melo
2014-01-01
Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy. PMID:25302615
Jacobs, Nathan T; Cortes, Daniel H; Peloquin, John M; Vresilovic, Edward J; Elliott, Dawn M
2014-08-22
Finite element (FE) models are advantageous in the study of intervertebral disc mechanics as the stress-strain distributions can be determined throughout the tissue and the applied loading and material properties can be controlled and modified. However, the complicated nature of the disc presents a challenge in developing an accurate and predictive disc model, which has led to limitations in FE geometry, material constitutive models and properties, and model validation. The objective of this study was to develop a new FE model of the intervertebral disc, to validate the model's nonlinear and time-dependent responses without tuning or calibration, and to evaluate the effect of changes in nucleus pulposus (NP), cartilaginous endplate (CEP), and annulus fibrosus (AF) material properties on the disc mechanical response. The new FE disc model utilized an analytically-based geometry. The model was created from the mean shape of human L4/L5 discs, measured from high-resolution 3D MR images and averaged using signed distance functions. Structural hyperelastic constitutive models were used in conjunction with biphasic-swelling theory to obtain material properties from recent tissue tests in confined compression and uniaxial tension. The FE disc model predictions fit within the experimental range (mean ± 95% confidence interval) of the disc's nonlinear response for compressive slow loading ramp, creep, and stress-relaxation simulations. Changes in NP and CEP properties affected the neutral-zone displacement but had little effect on the final stiffness during slow-ramp compression loading. These results highlight the need to validate FE models using the disc's full nonlinear response in multiple loading scenarios. PMID:24998992
Jacobs, Nathan T.; Cortes, Daniel H.; Peloquin, John M.; Vresilovic, Edward J.; Elliott, Dawn M.
2014-01-01
Finite element (FE) models are advantageous in the study of intervertebral disc mechanics as the stress–strain distributions can be determined throughout the tissue and the applied loading and material properties can be controlled and modified. However, the complicated nature of the disc presents a challenge in developing an accurate and predictive disc model, which has led to limitations in FE geometry, material constitutive models and properties, and model validation. The objective of this study was to develop a new FE model of the intervertebral disc, to validate the model’s nonlinear and time-dependent responses without tuning or calibration, and to evaluate the effect of changes in nucleus pulposus (NP), cartilaginous endplate (CEP), and annulus fibrosus (AF) material properties on the disc mechanical response. The new FE disc model utilized an analytically-based geometry. The model was created from the mean shape of human L4/L5 discs, measured from high-resolution 3D MR images and averaged using signed distance functions. Structural hyperelastic constitutive models were used in conjunction with biphasic-swelling theory to obtain material properties from recent tissue tests in confined compression and uniaxial tension. The FE disc model predictions fit within the experimental range (mean ± 95% confidence interval) of the disc’s nonlinear response for compressive slow loading ramp, creep, and stress-relaxation simulations. Changes in NP and CEP properties affected the neutral-zone displacement but had little effect on the final stiffness during slow-ramp compression loading. These results highlight the need to validate FE models using the disc’s full nonlinear response in multiple loading scenarios. PMID:24998992
Simple formulation of magnetoplasmadynamic acceleration
Sasoh, A. )
1994-03-01
A simple formulation of magnetoplasmadynamic acceleration has been made based on energy conservation relations and a generalized Ohm's law. An exhaust velocity is expressed using three characteristic parameters: (1) a dimensionless characteristic velocity [ital [tilde U
Potential vorticity formulation of compressible magnetohydrodynamics.
Arter, Wayne
2013-01-01
Compressible ideal magnetohydrodynamics is formulated in terms of the time evolution of potential vorticity and magnetic flux per unit mass using a compact Lie bracket notation. It is demonstrated that this simplifies analytic solution in at least one very important situation relevant to magnetic fusion experiments. Potentially important implications for analytic and numerical modelling of both laboratory and astrophysical plasmas are also discussed. PMID:23383802
Formulation Optimization of Arecoline Patches
Wu, Pao-Chu; Tsai, Pi-Ju; Lin, Shin-Chen; Huang, Yaw-Bin
2014-01-01
The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline. PMID:24707220
NASA Technical Reports Server (NTRS)
Newman, C. M.
1976-01-01
The constraints and limitations for STS Consumables Management are studied. Variables imposing constraints on the consumables related subsystems are identified, and a method determining constraint violations with the simplified consumables model in the Mission Planning Processor is presented.
Neonates need tailored drug formulations
Allegaert, Karel
2013-01-01
Drugs are very strong tools used to improve outcome in neonates. Despite this fact and in contrast to tailored perfusion equipment, incubators or ventilators for neonates, we still commonly use drug formulations initially developed for adults. We would like to make the point that drug formulations given to neonates need to be tailored for this age group. Besides the obvious need to search for active compounds that take the pathophysiology of the newborn into account, this includes the dosage and formulation. The dosage or concentration should facilitate the administration of low amounts and be flexible since clearance is lower in neonates with additional extensive between-individual variability. Formulations need to be tailored for dosage variability in the low ranges and also to the clinical characteristics of neonates. A specific focus of interest during neonatal drug development therefore is a need to quantify and limit excipient exposure based on the available knowledge of their safety or toxicity. Until such tailored vials and formulations become available, compounding practices for drug formulations in neonates should be evaluated to guarantee the correct dosing, product stability and safety. PMID:25254168
ERIC Educational Resources Information Center
Bierschenk, Bernhard; Bierschenk, Inger
The second of three articles on the ways in which people formulate their observations, this paper begins with a discussion of the assumptions underlying analytical and class-based models of cognition. The analytical approach to the measurement of cognition is found to be inappropriate because human cognition, and consequently language processing…
NASA Astrophysics Data System (ADS)
Heimbach, Patick; Menemenlis, Dimitris; Losch, Martin; Campin, Jean-Michel; Hill, Chris
The adjoint of an ocean general circulation model is at the heart of the ocean state estimation system of the Estimating the Circulation and Climate of the Ocean (ECCO) project. As part of an ongoing effort to extend ECCO to a coupled ocean/sea-ice estimation system, a dynamic and thermodynamic sea-ice model has been developed for the Massachusetts Institute of Technology general circulation model (MITgcm). One key requirement is the ability to generate, by means of automatic differentiation (AD), tangent linear (TLM) and adjoint (ADM) model code for the coupled MITgcm ocean/sea-ice system. This second part of a two-part paper describes aspects of the adjoint model. The adjoint ocean and sea-ice model is used to calculate transient sensitivities of solid (ice and snow) freshwater export through Lancaster Sound in the Canadian Arctic Archipelago (CAA). The adjoint state provides a complementary view of the dynamics. In particular, the transient, multi-year sensitivity patterns reflect dominant pathways and propagation timescales through the CAA as resolved by the model, thus shedding light on causal relationships, in the model, across the Archipelago. The computational cost of inferring such causal relationships from forward model diagnostics alone would be prohibitive. The role of the exact model trajectory around which the adjoint is calculated (and therefore of the exactness of the adjoint) is exposed through calculations using free-slip vs no-slip lateral boundary conditions. Effective ice thickness, sea surface temperature, and precipitation sensitivities, are discussed in detail as examples of the coupled sea-ice/ocean and atmospheric forcing control space. To test the reliability of the adjoint, finite-difference perturbation experiments were performed for each of these elements and the cost perturbations were compared to those "predicted" by the adjoint. Overall, remarkable qualitative and quantitative agreement is found. In particular, the adjoint correctly
Mackenzie, S G; Leinonen, I; Ferguson, N; Kyriazakis, I
2016-05-28
The objective of this study was to develop a novel methodology that enables pig diets to be formulated explicitly for environmental impact objectives using a Life Cycle Assessment (LCA) approach. To achieve this, the following methodological issues had to be addressed: (1) account for environmental impacts caused by both ingredient choice and nutrient excretion, (2) formulate diets for multiple environmental impact objectives and (3) allow flexibility to identify the optimal nutritional composition for each environmental impact objective. An LCA model based on Canadian pig farms was integrated into a diet formulation tool to compare the use of different ingredients in Eastern and Western Canada. By allowing the feed energy content to vary, it was possible to identify the optimum energy density for different environmental impact objectives, while accounting for the expected effect of energy density on feed intake. A least-cost diet was compared with diets formulated to minimise the following objectives: non-renewable resource use, acidification potential, eutrophication potential, global warming potential and a combined environmental impact score (using these four categories). The resulting environmental impacts were compared using parallel Monte Carlo simulations to account for shared uncertainty. When optimising diets to minimise a single environmental impact category, reductions in the said category were observed in all cases. However, this was at the expense of increasing the impact in other categories and higher dietary costs. The methodology can identify nutritional strategies to minimise environmental impacts, such as increasing the nutritional density of the diets, compared with the least-cost formulation. PMID:26987378
Integrated Formulation of Beacon-Based Exception Analysis for Multimissions
NASA Technical Reports Server (NTRS)
Mackey, Ryan; James, Mark; Park, Han; Zak, Mickail
2003-01-01
Further work on beacon-based exception analysis for multimissions (BEAM), a method of real-time, automated diagnosis of a complex electromechanical systems, has greatly expanded its capability and suitability of application. This expanded formulation, which fully integrates physical models and symbolic analysis, is described. The new formulation of BEAM expands upon previous advanced techniques for analysis of signal data, utilizing mathematical modeling of the system physics, and expert-system reasoning,
Technology Transfer Automated Retrieval System (TEKTRAN)
Due to the influence of evaporation on land-surface temperature, thermal remote sensing data provide valuable information regarding the surface moisture status. The Atmosphere-Land Exchange Inverse (ALEXI) model uses the morning surface temperature rise, as measured from a geostationary satellite p...
40 CFR 152.43 - Alternate formulations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... PESTICIDE REGISTRATION AND CLASSIFICATION PROCEDURES Registration Procedures § 152.43 Alternate formulations... label text of the alternate formulation product must be identical to that of the basic formulation....
40 CFR 152.43 - Alternate formulations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... PESTICIDE REGISTRATION AND CLASSIFICATION PROCEDURES Registration Procedures § 152.43 Alternate formulations... label text of the alternate formulation product must be identical to that of the basic formulation....
Jenkins, R.A.; Nestor, C.W.; Thompson, C.V.; Gayle, T.M.; Ma, C.Y.; Tomkins, B.A.; Moody, R.L.
1991-12-09
The overall objective of the work described in this report is four-fold: to (a) develop a standardized and experimentally validated approach to the sampling and chemical and physical characterization of the exhaust products of scaled-down rocket launch motors fired under experimentally controlled conditions at the Army`s Signature Characterization Facility (ASCF) at Redstone Arsenal in Huntsville, Alabama; (b) determine the composition of the exhaust produces; (c) assess the accuracy of a selected existing computer model for predicting the composition of major and minor chemical species; (d) recommended alternations to both the sampling and analysis strategy and the computer model in order to achieve greater congruence between chemical measurements and computer prediction. 34 refs., 2 figs., 35 tabs.
NASA Astrophysics Data System (ADS)
Jathar, S. H.; Miracolo, M. A.; Presto, A. A.; Adams, P. J.; Robinson, A. L.
2012-04-01
We present a methodology to model secondary organic aerosol (SOA) formation from the photo-oxidation of low-volatility organics (semi-volatile and intermediate volatility organic compounds). The model is parameterized and tested using SOA data collected during two field campaigns that characterized the atmospheric evolution of dilute gas-turbine engine emissions using a smog chamber. Photo-oxidation formed a significant amount of SOA, much of which cannot be explained based on the emissions of traditional, speciated precursors; we refer to this as non-traditional SOA (NT-SOA). The NT-SOA can be explained by emissions of low-volatility organic vapors measured using sorbents. Since these vapors could not be speciated, we employ a volatility-based approach to model NT-SOA formation. We show that the method proposed by Robinson et al. (2007) is unable to explain the timing of NT-SOA formation because it assumes a very modest reduction in volatility of the precursors with every oxidation reaction. In contrast, a Hybrid method, similar to models of traditional SOA formation, assumes a larger reduction in volatility with each oxidation step and results in a better reproduction of NT-SOA formation. The NT-SOA yields estimated for the low-volatility organic vapor emissions are similar to literature data for large n-alkanes and other low-volatility organics. The yields vary with fuel composition (JP8 versus Fischer-Tropsch) and engine load (idle versus non-idle). These differences are consistent with the expected contribution of high (aromatics and n-alkanes) and low (branched alkanes and oxygenated species) SOA forming species to the exhaust.
Hatfield, Laura A.; Gutreuter, Steve; Boogaard, Michael A.; Carlin, Bradley P.
2011-01-01
Estimation of extreme quantal-response statistics, such as the concentration required to kill 99.9% of test subjects (LC99.9), remains a challenge in the presence of multiple covariates and complex study designs. Accurate and precise estimates of the LC99.9 for mixtures of toxicants are critical to ongoing control of a parasitic invasive species, the sea lamprey, in the Laurentian Great Lakes of North America. The toxicity of those chemicals is affected by local and temporal variations in water chemistry, which must be incorporated into the modeling. We develop multilevel empirical Bayes models for data from multiple laboratory studies. Our approach yields more accurate and precise estimation of the LC99.9 compared to alternative models considered. This study demonstrates that properly incorporating hierarchical structure in laboratory data yields better estimates of LC99.9 stream treatment values that are critical to larvae control in the field. In addition, out-of-sample prediction of the results of in situ tests reveals the presence of a latent seasonal effect not manifest in the laboratory studies, suggesting avenues for future study and illustrating the importance of dual consideration of both experimental and observational data.
Islam, Dilara; Ruamsap, Nattaya; Khantapura, Patchariya; Aksomboon, Ajchara; Srijan, Apichai; Wongstitwilairoong, Boonchai; Bodhidatta, Ladaporn; Gettayacamin, Montip; Venkatesan, Malabi M; Mason, Carl J
2014-01-01
Shigellosis is a worldwide disease, characterized by abdominal pain, fever, vomiting, and the passage of blood- and mucus-streaked stools. Rhesus monkeys and other primates are the only animals that are naturally susceptible to shigellosis. A suitable animal model is required for the pre-clinical evaluation of vaccines candidates. In this study, the minimal dose of Shigella dysenteriae1 1617 strain required to produce dysentery in four of five (80% attack rate) monkeys using an escalating dose range for three groups [2 × 108, 2 × 109 and 2 × 1010 colony forming unit (CFU)] was determined. In addition, the monkeys were re-infected. The identified optimal challenge dose was 2 × 109 CFU; this dose elicited 60% protection in monkeys when they were re-challenged with a one log higher dose (2 × 1010 CFU). The challenge dose, 2 × 1010 CFU, produced severe dysentery in all monkeys, with one monkey dying within 24 h, elicited 100% protection when re-challenged with the same dose. All monkeys exhibited immune responses. This study concludes that the rhesus monkey model closely mimics the disease and immune response seen in humans and is a suitable animal model for the pre-clinical evaluation of Shigella vaccine candidates. Prior infection with the 1617 strain can protect monkeys against subsequent re-challenges with homologous strains. PMID:24028276
Islam, Dilara; Ruamsap, Nattaya; Khantapura, Patchariya; Aksomboon, Ajchara; Srijan, Apichai; Wongstitwilairoong, Boonchai; Bodhidatta, Ladaporn; Gettayacamin, Montip; Venkatesan, Malabi M; Mason, Carl J
2014-06-01
Shigellosis is a worldwide disease, characterized by abdominal pain, fever, vomiting, and the passage of blood- and mucus-streaked stools. Rhesus monkeys and other primates are the only animals that are naturally susceptible to shigellosis. A suitable animal model is required for the pre-clinical evaluation of vaccines candidates. In this study, the minimal dose of Shigella dysenteriae1 1617 strain required to produce dysentery in four of five (80% attack rate) monkeys using an escalating dose range for three groups [2 × 10(8) , 2 × 10(9) and 2 × 10(10) colony forming unit (CFU)] was determined. In addition, the monkeys were re-infected. The identified optimal challenge dose was 2 × 10(9) CFU; this dose elicited 60% protection in monkeys when they were re-challenged with a one log higher dose (2 × 10(10) CFU). The challenge dose, 2 × 10(10) CFU, produced severe dysentery in all monkeys, with one monkey dying within 24 h, elicited 100% protection when re-challenged with the same dose. All monkeys exhibited immune responses. This study concludes that the rhesus monkey model closely mimics the disease and immune response seen in humans and is a suitable animal model for the pre-clinical evaluation of Shigella vaccine candidates. Prior infection with the 1617 strain can protect monkeys against subsequent re-challenges with homologous strains. PMID:24028276
Mixed formulation for frictionless contact problems
NASA Technical Reports Server (NTRS)
Noor, Ahmed K.; Kim, Kyun O.
1989-01-01
Simple mixed finite element models and a computational precedure are presented for the solution of frictionless contact problems. The analytical formulation is based on a form of Reissner's large rotation theory of the structure with the effects of transverse shear deformation included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the internal forces (stress resultants), the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The element characteristic array are obtained by using a modified form of the two-field Hellinger-Reissner mixed variational principle. The internal forces and the Lagrange multipliers are allowed to be discontinuous at interelement boundaries. The Newton-Raphson iterative scheme is used for the solution of the nonlinear algebraic equations, and the determination of the contact area and the contact pressures.
Parallelized solvers for heat conduction formulations
NASA Technical Reports Server (NTRS)
Padovan, Joe; Kwang, Abel
1991-01-01
Based on multilevel partitioning, this paper develops a structural parallelizable solution methodology that enables a significant reduction in computational effort and memory requirements for very large scale linear and nonlinear steady and transient thermal (heat conduction) models. Due to the generality of the formulation of the scheme, both finite element and finite difference simulations can be treated. Diverse model topologies can thus be handled, including both simply and multiply connected (branched/perforated) geometries. To verify the methodology, analytical and numerical benchmark trends are verified in both sequential and parallel computer environments.
Decontamination formulation with sorbent additive
Tucker; Mark D. , Comstock; Robert H.
2007-10-16
A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a bleaching activator, a sorbent additive, and water. The highly adsorbent, water-soluble sorbent additive (e.g., sorbitol or mannitol) is used to "dry out" one or more liquid ingredients, such as the liquid bleaching activator (e.g., propylene glycol diacetate or glycerol diacetate) and convert the activator into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field.
Pelosi, Assunta; Piedrafita, David; De Guzman, Giorgio; Shepherd, Robert; Hamill, John D.; Meeusen, Els; Walmsley, Amanda M.
2012-01-01
Antigen-specific antibody responses against a model antigen (the B subunit of the heat labile toxin of enterotoxigenic Escherichia coli, LTB) were studied in sheep following oral immunisation with plant-made and delivered vaccines. Delivery from a root-based vehicle resulted in antigen-specific immune responses in mucosal secretions of the abomasum and small intestine and mesenteric lymph nodes. Immune responses from the corresponding leaf-based vaccine were more robust and included stimulation of antigen-specific antibodies in mucosal secretions of the abomasum. These findings suggest that oral delivery of a plant bioencapsulated antigen can survive passage through the rumen to elicit mucosal and systemic immune responses in sheep. Moreover, the plant tissue used as the vaccine delivery vehicle affects the magnitude of these responses. PMID:23285224
Mathematical programming formulations for satellite synthesis
NASA Technical Reports Server (NTRS)
Bhasin, Puneet; Reilly, Charles H.
1987-01-01
The problem of satellite synthesis can be described as optimally allotting locations and sometimes frequencies and polarizations, to communication satellites so that interference from unwanted satellite signals does not exceed a specified threshold. In this report, mathematical programming models and optimization methods are used to solve satellite synthesis problems. A nonlinear programming formulation which is solved using Zoutendijk's method and a gradient search method is described. Nine mixed integer programming models are considered. Results of computer runs with these nine models and five geographically compatible scenarios are presented and evaluated. A heuristic solution procedure is also used to solve two of the models studied. Heuristic solutions to three large synthesis problems are presented. The results of our analysis show that the heuristic performs very well, both in terms of solution quality and solution time, on the two models to which it was applied. It is concluded that the heuristic procedure is the best of the methods considered for solving satellite synthesis problems.
Trigger chemistries for better industrial formulations.
Wang, Hsuan-Chin; Zhang, Yanfeng; Possanza, Catherine M; Zimmerman, Steven C; Cheng, Jianjun; Moore, Jeffrey S; Harris, Keith; Katz, Joshua S
2015-04-01
In recent years, innovations and consumer demands have led to increasingly complex liquid formulations. These growing complexities have provided industrial players and their customers access to new markets through product differentiation, improved performance, and compatibility/stability with other products. One strategy for enabling more complex formulations is the use of active encapsulation. When encapsulation is employed, strategies are required to effect the release of the active at the desired location and time of action. One particular route that has received significant academic research effort is the employment of triggers to induce active release upon a specific stimulus, though little has translated for industrial use to date. To address emerging industrial formulation needs, in this review, we discuss areas of trigger release chemistries and their applications specifically as relevant to industrial use. We focus the discussion on the use of heat, light, shear, and pH triggers as applied in several model polymeric systems for inducing active release. The goal is that through this review trends will emerge for how technologies can be better developed to maximize their value through industrial adaptation. PMID:25768973
A formulation and analysis of combat games
NASA Technical Reports Server (NTRS)
Heymann, M.; Ardema, M. D.; Rajan, N.
1985-01-01
Combat is formulated as a dynamical encounter between two opponents, each of whom has offensive capabilities and objectives. With each opponent is associated a target in the event space in which he endeavors to terminate the combat, thereby winning. If the combat terminates in both target sets simultaneously or in neither, a joint capture or a draw, respectively, is said to occur. Resolution of the encounter is formulated as a combat game; namely, as a pair of competing event-constrained differential games. If exactly one of the players can win, the optimal strategies are determined from a resulting constrained zero-sum differential game. Otherwise the optimal strategies are computed from a resulting non-zero-sum game. Since optimal combat strategies frequencies may not exist, approximate of delta-combat games are also formulated leading to approximate or delta-optimal strategies. To illustrate combat games, an example, called the turret game, is considered. This game may be thought of as a highly simplified model of air combat, yet it is sufficiently complex to exhibit a rich variety of combat behavior, much of which is not found in pursuit-evasion games.
Bae, Woong Jin; Bashraheel, Fahad; Choi, Sae Woong; Kim, Su Jin; Kim, Sae Woong; Yoon, Byung Il
2016-01-01
Objective The aim of this study was to investigate the anti-inflammatory and anti-microbial effects of a new herbal formula (WSY-1075) in a chronic bacterial prostatitis rat model. Methods Thirty two male Wistar rats were used in the study. Experimental chronic bacterial prostatitis was induced by instillation of bacterial suspension (Escherichia coli 108 per mL) into the prostatic urethra. Animals were followed for 4 weeks. After the induction of prostatitis, the rats were randomly divided into one of four treatment groups: control (n=8), ciprofloxacin (n=8), WSY-1075 (400 mg/kg) (n=8), and WSY-1075 (400 mg/kg) + ciprofloxacin (n=8). After 4 weeks of treatment, the prostatic pro-inflammatory cytokine [tumor necrosis factor-α, interleukin (IL)-6, and IL-8] levels, anti-oxidant effects (superoxide dismutase) and histological findings were noted. Results The use of ciprofloxacin, WSY-1075, and WSY-1075 with ciprofloxacin showed statistically significant decreases in bacterial growth and improvements in the reduction of prostatic inflammation compared with the control group (P<0.05). The WSY-1075 with ciprofloxacin group showed a statistically significant decrease in bacterial growth and improvement in prostatic inflammation compared with the ciprofloxacin group (P<0.05). Conclusions These results suggest that WSY-1075 may have anti-inflammatory and antimicrobial effects, as well as a synergistic effect with ciprofloxacin. Therefore, we suggest that the combination of WSY-1075 and ciprofloxacin may be effective in treating chronic bacterial prostatitis to obtain a higher rate of treatment success.
ERIC Educational Resources Information Center
Rogers, Gregory M.; Reinecke, Mark A.; Curry, John F.
2005-01-01
For the Treatment for Adolescents With Depression Study (TADS), a cognitive-behavioral therapy (CBT) manual was developed with the aim of balancing standardization and flexibility. In this article, we describe the manual's case formulation procedures, which served as one major mechanism of flexibility in TADS CBT. We first describe the essential…
TERATOLOGY OF A ZINEB FORMULATION
The purpose of the present study was to evaluate the teratogenic potential of a zineb formulation. An initial toxicity study indicated that oral doses of 1,000 or 2,000 mg/kg/day adversely affected the weight gain of nonpregnant rats but not nonpregnant mice. In the teratology st...
Convex Formulations of Learning from Crowds
NASA Astrophysics Data System (ADS)
Kajino, Hiroshi; Kashima, Hisashi
It has attracted considerable attention to use crowdsourcing services to collect a large amount of labeled data for machine learning, since crowdsourcing services allow one to ask the general public to label data at very low cost through the Internet. The use of crowdsourcing has introduced a new challenge in machine learning, that is, coping with low quality of crowd-generated data. There have been many recent attempts to address the quality problem of multiple labelers, however, there are two serious drawbacks in the existing approaches, that are, (i) non-convexity and (ii) task homogeneity. Most of the existing methods consider true labels as latent variables, which results in non-convex optimization problems. Also, the existing models assume only single homogeneous tasks, while in realistic situations, clients can offer multiple tasks to crowds and crowd workers can work on different tasks in parallel. In this paper, we propose a convex optimization formulation of learning from crowds by introducing personal models of individual crowds without estimating true labels. We further extend the proposed model to multi-task learning based on the resemblance between the proposed formulation and that for an existing multi-task learning model. We also devise efficient iterative methods for solving the convex optimization problems by exploiting conditional independence structures in multiple classifiers.
Laffont, Celine M; Gomeni, Roberto; Heidbreder, Christian; Jones, J P; Nasser, Azmi F
2016-07-01
RBP-6000 is a novel sustained-release formulation of buprenorphine for the treatment of opioid use disorder, which has been designed for once-monthly (28 days) subcutaneous (SC) injections. A population pharmacokinetic (PK) model was developed to describe the time course of buprenorphine plasma concentrations after repeated SC injections of RBP-6000 at 50 mg, 100 mg, 200 mg, or 300 mg in treatment-seeking opioid-dependent subjects previously on sublingual buprenorphine (Subutex(®) ) treatment. The μ-opioid receptor occupancy was predicted using a previously developed PK/PD Emax model. The results of the population PK analysis jointly with the predicted level of μ-opioid receptor occupancy provided quantitative criteria for clinical dose selection for RBP-6000: the dose of 300 mg every 28 days seems appropriate for immediately achieving an effective exposure after the first SC injection and to maintain effective levels of exposure during chronic treatment. Furthermore, simulations conducted to evaluate the potential impact of a holiday in drug intake indicated that in the unexpected event of a 2-week holiday, levels of μ-opioid receptor occupancy remained consistently above 70% with no significant loss of drug efficacy. This analysis indicated that RBP-6000 has the potential for becoming an effective treatment for opioid-dependent subjects by addressing compliance issues associated with the current once-a-day treatments. PMID:26479717
Francois, Marianne M; Shashkov, Misha J; Lowrie, Robert B; Dendy, Edward D
2010-10-13
We compare a staggered Lagrangian formulation with a cell-centered Lagrangian formulation for a two-material compressible flow. In both formulation, we assume a single velocity field and rely on pressure relaxation techniques to close the system of equations. We employ Tipton's mixture model for both formulation. However, for the cell-centered formulation, employing Tipton's model for the mixture cell results in loss of conservation of total energy. We propose a numerical algorithm to correct this energy discrepancy. We test both algorithms on the two-materials Sod shock tube test problem and compare the results with the analytical solution.
A novel metered dose transdermal spray formulation for oxybutynin.
Bakshi, A; Bajaj, A; Malhotra, G; Madan, M; Amrutiya, N
2008-11-01
The objective of the present work was to develop a metered dose spray formulation for transdermal delivery of oxybutynin and to carry out the in vitro characterization of the optimized formulation. Oxybutynin release from a series of ethanol/acetone/methylal based formulations was assessed in vitro and the developed formulation was used for delivery from a metered dose spray. Various qualitative and quantitative parameters like spray pattern, particle size distribution, pH, evaporation time, pump seal efficiency test, average weight per metered dose, content per spray and content uniformity were evaluated. The different film forming agents were assessed and carbopol (0.5%) and lutrol (0.1%) were found to give good clarity of solution, evaporation rate, spray pattern and tackiness of the film. Diffusion studies of the optimized formulations through the semipermeable membrane showed the release of drug to the extent of almost 50% over a period of 24 h. Stability studies were conducted as per ICH guidelines and indicated that formulations were stable. Skin irritation studies were performed using rabbit as an animal model. The results obtained show that the metered dose transdermal spray formulation can be a promising and innovative therapeutic system for the transdermal administration of oxybutynin. PMID:21369433
A Novel Metered Dose Transdermal Spray Formulation for Oxybutynin
Bakshi, A.; Bajaj, A.; Malhotra, G.; Madan, M.; Amrutiya, N.
2008-01-01
The objective of the present work was to develop a metered dose spray formulation for transdermal delivery of oxybutynin and to carry out the in vitro characterization of the optimized formulation. Oxybutynin release from a series of ethanol/acetone/methylal based formulations was assessed in vitro and the developed formulation was used for delivery from a metered dose spray. Various qualitative and quantitative parameters like spray pattern, particle size distribution, pH, evaporation time, pump seal efficiency test, average weight per metered dose, content per spray and content uniformity were evaluated. The different film forming agents were assessed and carbopol (0.5%) and lutrol (0.1%) were found to give good clarity of solution, evaporation rate, spray pattern and tackiness of the film. Diffusion studies of the optimized formulations through the semipermeable membrane showed the release of drug to the extent of almost 50% over a period of 24 h. Stability studies were conducted as per ICH guidelines and indicated that formulations were stable. Skin irritation studies were performed using rabbit as an animal model. The results obtained show that the metered dose transdermal spray formulation can be a promising and innovative therapeutic system for the transdermal administration of oxybutynin. PMID:21369433
Significance of Strain in Formulation in Theory of Solid Mechanics
NASA Technical Reports Server (NTRS)
Patnaik, Surya N.; Coroneos, Rula M.; Hopkins, Dale A.
2003-01-01
The basic theory of solid mechanics was deemed complete circa 1860 when St. Venant provided the strain formulation or the field compatibility condition. The strain formulation was incomplete. The missing portion has been formulated and identified as the boundary compatibility condition (BCC). The BCC, derived through a variational formulation, has been verified through integral theorem and solution of problems. The BCC, unlike the field counterpart, do not trivialize when expressed in displacements. Navier s method and the stiffness formulation have to account for the extra conditions especially at the inter-element boundaries in a finite element model. Completion of the strain formulation has led to the revival of the direct force calculation methods: the Integrated Force Method (IFM) and its dual (IFMD) for finite element analysis, and the completed Beltrami-Michell formulation (CBMF) in elasticity. The benefits from the new methods in elasticity, in finite element analysis, and in design optimization are discussed. Existing solutions and computer codes may have to be adjusted for the compliance of the new conditions. Complacency because the discipline is over a century old and computer codes have been developed for half a century can lead to stagnation of the discipline.
Sikorska, Marianna; Lanthier, Patricia; Miller, Harvey; Beyers, Melissa; Sodja, Caroline; Zurakowski, Bogdan; Gangaraju, Sandhya; Pandey, Siyaram; Sandhu, Jagdeep K.
2016-01-01
Although the support for the use of antioxidants, such as coenzyme Q10 (CoQ10), to treat Parkinson’s disease (PD) comes from the extensive scientific evidence, the results of conducted thus far clinical trials are inconclusive. It is assumed that the efficacy of CoQ10 is hindered by insolubility, poor bioavailability, and lack of brain penetration. We have developed a nanomicellar formulation of CoQ10 (Ubisol-Q10) with improved properties, including the brain penetration, and tested its effectiveness in mouse MPTP (1-methyl-4-phenyl- 1, 2, 3, 6-tetrahydropyridine) model with the objectives to assess its potential use as an adjuvant therapy for PD. We used a subchronic MPTP model (5-daily MPTP injections), characterized by 50% loss of dopamine neurons over a period of 28 days. Ubisol-Q10 was delivered in drinking water. Prophylactic application of Ubisol-Q10, started 2 weeks before the MPTP exposure, significantly offset the neurotoxicity (approximately 50% neurons died in MPTP group vs. 17% in MPTP+ Ubisol-Q10 group by day 28). Therapeutic application of Ubisol-Q10, given after the last MPTP injection, was equally effective. At the time of intervention on day 5 nearly 25% of dopamine neurons were already lost, but the treatment saved the remaining 25% of cells, which otherwise would have died by day 28. This was confirmed by cell counts, analyses of striatal dopamine levels, and improved animals’ motor skill on a beam walk test. Similar levels of neuroprotection were obtained with 3 different Ubisol-Q10 concentrations tested, that is, 30 mg, 6 mg, or 3 mg CoQ10/kg body weight/day, showing clearly that high doses of CoQ10 were not required to deliver these effects. Furthermore, the Ubisol-Q10 treatments brought about a robust astrocytic activation in the brain parenchyma, indicating that astroglia played an active role in this neuroprotection. Thus, we have shown for the first time that Ubisol-Q10 was capable of halting the neurodegeneration already in progress
Sikorska, Marianna; Lanthier, Patricia; Miller, Harvey; Beyers, Melissa; Sodja, Caroline; Zurakowski, Bogdan; Gangaraju, Sandhya; Pandey, Siyaram; Sandhu, Jagdeep K
2014-10-01
Although the support for the use of antioxidants, such as coenzyme Q(10) (CoQ(10)), to treat Parkinson's disease (PD) comes from the extensive scientific evidence, the results of conducted thus far clinical trials are inconclusive. It is assumed that the efficacy of CoQ(10) is hindered by insolubility, poor bioavailability, and lack of brain penetration. We have developed a nanomicellar formulation of CoQ(10) (Ubisol-Q(10)) with improved properties, including the brain penetration, and tested its effectiveness in mouse MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) model with the objectives to assess its potential use as an adjuvant therapy for PD. We used a subchronic MPTP model (5-daily MPTP injections), characterized by 50% loss of dopamine neurons over a period of 28 days. Ubisol-Q(10) was delivered in drinking water. Prophylactic application of Ubisol-Q(10), started 2 weeks before the MPTP exposure, significantly offset the neurotoxicity (approximately 50% neurons died in MPTP group vs. 17% in MPTP+ Ubisol-Q(10) group by day 28). Therapeutic application of Ubisol-Q(10), given after the last MPTP injection, was equally effective. At the time of intervention on day 5 nearly 25% of dopamine neurons were already lost, but the treatment saved the remaining 25% of cells, which otherwise would have died by day 28. This was confirmed by cell counts, analyses of striatal dopamine levels, and improved animals' motor skill on a beam walk test. Similar levels of neuroprotection were obtained with 3 different Ubisol-Q(10) concentrations tested, that is, 30 mg, 6 mg, or 3 mg CoQ(10)/kg body weight/day, showing clearly that high doses of CoQ(10) were not required to deliver these effects. Furthermore, the Ubisol-Q(10) treatments brought about a robust astrocytic activation in the brain parenchyma, indicating that astroglia played an active role in this neuroprotection. Thus, we have shown for the first time that Ubisol-Q(10) was capable of halting the
Shock initiation of an {epsilon}-CL-20-estane formulation
Tarver, C.M.; Simpson, R.L.; Urtiew, P.A.
1995-07-19
The shock sensitivity of a pressed solid explosive formulation, LX-19, containing 95.2% by weight epsilon phase 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) and 4.8% Estane binder, was determined using the wedge test and embedded manganin pressure gauge techniques. This formulation was shown to be slightly more sensitive than LX-14, which contains 95.5% HMX and 4.5% Estane binder. The measured pressure histories for LX-19 were very similar to those obtained using several HMX-inert binder formulations. An Ignition and Growth reactive model for LX-19 was developed which differed from those for HMX-inert binder formulations only by a 25% higher hot spot growth rate.
Shock initiation of an {epsilon}-CL-20-estane formulation
Tarver, C.M.; Simpson, R.L.; Urtiew, P.A.
1996-05-01
The shock sensitivity of a pressed solid explosive formulation, LX-19, containing 95.2{percent} by weight epsilon phase 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) and 4.8{percent} Estane binder, was determined using the wedge test and embedded manganin pressure gauge techniques. This formulation was shown to be slightly more sensitive than LX-14, which contains 95.5{percent} HMX and 4.5{percent} Estane binder. The measured pressure histories for LX-19 were very similar to those obtained using several HMX-inert binder formulations. An Ignition and Growth reactive flow model for LX-19 was developed which differed from those for HMX-inert binder formulations only by a 25{percent} higher hot spot growth rate. {copyright} {ital 1996 American Institute of Physics.}
Shock initiation of an ɛ-CL-20-estane formulation
NASA Astrophysics Data System (ADS)
Tarver, C. M.; Simpson, R. L.; Urtiew, P. A.
1996-05-01
The shock sensitivity of a pressed solid explosive formulation, LX-19, containing 95.2% by weight epsilon phase 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) and 4.8% Estane binder, was determined using the wedge test and embedded manganin pressure gauge techniques. This formulation was shown to be slightly more sensitive than LX-14, which contains 95.5% HMX and 4.5% Estane binder. The measured pressure histories for LX-19 were very similar to those obtained using several HMX-inert binder formulations. An Ignition and Growth reactive flow model for LX-19 was developed which differed from those for HMX-inert binder formulations only by a 25% higher hot spot growth rate.
Intermediate release formulations of diclofenac potassium tablets for IVIVC.
Ali, Huma; Shoaib, Muhammad Harris; Zafar, Farya; Bushra, Rabia; Yasmin, Riffat; Siddiqui, Shehla; Alam, Zafar M
2016-07-01
In recent days response surface methodology (RSM) has widely been applied for development and optimization of cost effective formulations with required quality. Study comprised of three steps including micromeritic comparison of different powder blends of placebo and diclofenac potassium (DP), formulation designing with CCRD (Design Expert, version 7.0.0), and stability testing of selected formulations by using R Gui. Ten formulations (F11-F20) were developed using microcrystalline cellulose (Avicel PH-102) (X1) (13-72%), methocel K15M (X2) (6.59-23.4%) and magnesium stearate (X3) (1.32-4.68%), while responses were % friability and % drug release. Blending rate constant was determined at 3, 6, 9 and 12 minutes. The results of physicochemical parameters were found within acceptable limits. After in vitro testing at pH 1.2, pH 4.5 and pH 6.8, mechanism of drug release, kinetic analysis and statistical evaluation were carried out by model - independent, model-dependent and one-way ANOVA methods. Most formulations followed zero order kinetics at higher pH. Fickian release (0.326 ≤ n ≤0.449) was observed with β greater than 0.5 and less than 1. ANOVA indicated no significant variation within and between formulations as p-values were found to be > 0.05. PMID:27393442
Eulerian Formulation of Spatially Constrained Elastic Rods
NASA Astrophysics Data System (ADS)
Huynen, Alexandre
Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is in contact with a stiff constraining surface. The research work presented in this doctoral dissertation formulates a computational model for the solution of elastic rods constrained inside or around frictionless tube-like surfaces. The segmentation strategy adopted to cope with this complex class of problems consists in sequencing the global problem into, comparatively simpler, elementary problems either in continuous contact with the constraint or contact-free between their extremities. Within the conventional Lagrangian formulation of elastic rods, this approach is however associated with two major drawbacks. First, the boundary conditions specifying the locations of the rod centerline at both extremities of each elementary problem lead to the establishment of isoperimetric constraints, i.e., integral constraints on the unknown length of the rod. Second, the assessment of the unilateral contact condition requires, in principle, the comparison of two curves parametrized by distinct curvilinear coordinates, viz. the rod centerline and the constraint axis. Both conspire to burden the computations associated with the method. To streamline the solution along the elementary problems and rationalize the assessment of the unilateral contact condition, the rod governing equations are reformulated within the Eulerian framework of the constraint. The methodical exploration of both types of elementary problems leads to specific formulations of the rod governing equations that stress the profound connection between the mechanics of the rod and the geometry of the constraint surface. The proposed Eulerian reformulation, which restates the rod local equilibrium in terms of the curvilinear coordinate associated with the constraint axis, describes the rod deformed configuration
Geometric nonlinear formulation for thermal-rigid-flexible coupling system
NASA Astrophysics Data System (ADS)
Fan, Wei; Liu, Jin-Yang
2013-10-01
This paper develops geometric nonlinear hybrid formulation for flexible multibody system with large deformation considering thermal effect. Different from the conventional formulation, the heat flux is the function of the rotational angle and the elastic deformation, therefore, the coupling among the temperature, the large overall motion and the elastic deformation should be taken into account. Firstly, based on nonlinear strain-displacement relationship, variational dynamic equations and heat conduction equations for a flexible beam are derived by using virtual work approach, and then, Lagrange dynamics equations and heat conduction equations of the first kind of the flexible multibody system are obtained by leading into the vectors of Lagrange multiplier associated with kinematic and temperature constraint equations. This formulation is used to simulate the thermal included hub-beam system. Comparison of the response between the coupled system and the uncoupled system has revealed the thermal chattering phenomenon. Then, the key parameters for stability, including the moment of inertia of the central body, the incident angle, the damping ratio and the response time ratio, are analyzed. This formulation is also used to simulate a three-link system applied with heat flux. Comparison of the results obtained by the proposed formulation with those obtained by the approximate nonlinear model and the linear model shows the significance of considering all the nonlinear terms in the strain in case of large deformation. At last, applicability of the approximate nonlinear model and the linear model are clarified in detail.
Geometric nonlinear formulation for thermal-rigid-flexible coupling system
NASA Astrophysics Data System (ADS)
Fan, Wei; Liu, Jin-Yang
2013-09-01
This paper develops geometric nonlinear hybrid formulation for flexible multibody system with large deformation