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Sample records for modified green-ampt model

  1. The combined use of Green-Ampt model and Curve Number method as an empirical tool for loss estimation

    Science.gov (United States)

    Petroselli, A.; Grimaldi, S.; Romano, N.

    2012-12-01

    The Soil Conservation Service - Curve Number (SCS-CN) method is a popular rainfall-runoff model widely used to estimate losses and direct runoff from a given rainfall event, but its use is not appropriate at sub-daily time resolution. To overcome this drawback, a mixed procedure, referred to as CN4GA (Curve Number for Green-Ampt), was recently developed including the Green-Ampt (GA) infiltration model and aiming to distribute in time the information provided by the SCS-CN method. The main concept of the proposed mixed procedure is to use the initial abstraction and the total volume given by the SCS-CN to calibrate the Green-Ampt soil hydraulic conductivity parameter. The procedure is here applied on a real case study and a sensitivity analysis concerning the remaining parameters is presented; results show that CN4GA approach is an ideal candidate for the rainfall excess analysis at sub-daily time resolution, in particular for ungauged basin lacking of discharge observations.

  2. Mixing the Green-Ampt model and Curve Number method as an empirical tool for rainfall excess estimation in small ungauged catchments.

    Science.gov (United States)

    Grimaldi, S.; Petroselli, A.; Romano, N.

    2012-04-01

    The Soil Conservation Service - Curve Number (SCS-CN) method is a popular rainfall-runoff model that is widely used to estimate direct runoff from small and ungauged basins. The SCS-CN is a simple and valuable approach to estimate the total stream-flow volume generated by a storm rainfall, but it was developed to be used with daily rainfall data. To overcome this drawback, we propose to include the Green-Ampt (GA) infiltration model into a mixed procedure, which is referred to as CN4GA (Curve Number for Green-Ampt), aiming to distribute in time the information provided by the SCS-CN method so as to provide estimation of sub-daily incremental rainfall excess. For a given storm, the computed SCS-CN total net rainfall amount is used to calibrate the soil hydraulic conductivity parameter of the Green-Ampt model. The proposed procedure was evaluated by analyzing 100 rainfall-runoff events observed in four small catchments of varying size. CN4GA appears an encouraging tool for predicting the net rainfall peak and duration values and has shown, at least for the test cases considered in this study, a better agreement with observed hydrographs than that of the classic SCS-CN method.

  3. Green-Ampt approximations: A comprehensive analysis

    Science.gov (United States)

    Ali, Shakir; Islam, Adlul; Mishra, P. K.; Sikka, Alok K.

    2016-04-01

    Green-Ampt (GA) model and its modifications are widely used for simulating infiltration process. Several explicit approximate solutions to the implicit GA model have been developed with varying degree of accuracy. In this study, performance of nine explicit approximations to the GA model is compared with the implicit GA model using the published data for broad range of soil classes and infiltration time. The explicit GA models considered are Li et al. (1976) (LI), Stone et al. (1994) (ST), Salvucci and Entekhabi (1994) (SE), Parlange et al. (2002) (PA), Barry et al. (2005) (BA), Swamee et al. (2012) (SW), Ali et al. (2013) (AL), Almedeij and Esen (2014) (AE), and Vatankhah (2015) (VA). Six statistical indicators (e.g., percent relative error, maximum absolute percent relative error, average absolute percent relative errors, percent bias, index of agreement, and Nash-Sutcliffe efficiency) and relative computer computation time are used for assessing the model performance. Models are ranked based on the overall performance index (OPI). The BA model is found to be the most accurate followed by the PA and VA models for variety of soil classes and infiltration periods. The AE, SW, SE, and LI model also performed comparatively better. Based on the overall performance index, the explicit models are ranked as BA > PA > VA > LI > AE > SE > SW > ST > AL. Results of this study will be helpful in selection of accurate and simple explicit approximate GA models for solving variety of hydrological problems.

  4. Empirical solution of Green-Ampt equation using soil conservation service - curve number values

    Science.gov (United States)

    Grimaldi, S.; Petroselli, A.; Romano, N.

    2012-09-01

    The Soil Conservation Service - Curve Number (SCS-CN) method is a popular widely used rainfall-runoff model for quantifying the total stream-flow volume generated by storm rainfall, but its application is not appropriate for sub-daily resolutions. In order to overcome this drawback, the Green-Ampt (GA) infiltration equation is considered and an empirical solution is proposed and evaluated. The procedure, named CN4GA (Curve Number for Green-Ampt), aims to calibrate the Green-Ampt model parameters distributing in time the global information provided by the SCS-CN method. The proposed procedure is evaluated by analysing observed rainfall-runoff events; results show that CN4GA seems to provide better agreement with the observed hydrographs respect to the classic SCS-CN method.

  5. Modelagem da infiltração de água no solo sob condições de estratificação utilizando-se a equação de Green-Ampt Modeling of water infiltration in soil under stratified conditions using the Green-Ampt equation

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    Roberto A. Cecílio

    2003-12-01

    Full Text Available A infiltração de água no solo é um dos mais significantes processos do ciclo hidrológico. A equação de Green-Ampt (GA é bastante utilizada na modelagem da infiltração; entretanto, diversos autores alertam para a necessidade de adequação de seus parâmetros de entrada (umidade de saturação (tetas; condutividade hidráulica do solo saturado (K0 e potencial matricial na frente de umedecimento (psi. Neste sentido, avaliou-se a aplicabilidade do modelo de GA, assim como as diversas proposições de adequação de K0 e psi, em um Latossolo Vermelho-Amarelo sob condições de estratificação. Determinaram-se a infiltração acumulada (I, a taxa de infiltração (Ti e as características físicas do perfil necessárias para a aplicação do modelo. Foram feitas simulações com base na combinação de seis metodologias para a determinação de psi e três para a condutividade hidráulica da zona de transmissão (Kw, verificando-se que as combinações seguintes simularam bem o processo de infiltração: Kw igual a 0,5 K0 associado a psi determinado com base na umidade inicial do solo (psi (tetai; Kw igual à taxa de infiltração estável (Tie associado a psi igual à média entre psi (tetai e psi relativo à umidade de saturação de campo (psi (tetaw; e Kw igual a K0 associado a psi calculado com base na textura e porosidade do solo (psi(textura e Kw igual à Tie associado a psi(textura.Soil water infiltration is one of the most important processes of the hydrological cycle. The Green and Ampt equation (GA is quite used to simulate the infiltration process, however, several authors showed the necessity of some adaptations in the GA parameters: saturation moisture (thetas, hydraulic conductivity (K0 and mean suction in the wetting front (psi. An evaluation was made of the GA model and of the several correction propositions of K0 and psi, applied in a stratified Red-Yellow Latosol. A soil box filled with soil material belonging to three

  6. Parameter sensitivity analysis of the mixed Green-Ampt/Curve-Number method for rainfall excess estimation in small ungauged catchments

    Science.gov (United States)

    Romano, N.; Petroselli, A.; Grimaldi, S.

    2012-04-01

    With the aim of combining the practical advantages of the Soil Conservation Service - Curve Number (SCS-CN) method and Green-Ampt (GA) infiltration model, we have developed a mixed procedure, which is referred to as CN4GA (Curve Number for Green-Ampt). The basic concept is that, for a given storm, the computed SCS-CN total net rainfall amount is used to calibrate the soil hydraulic conductivity parameter of the Green-Ampt model so as to distribute in time the information provided by the SCS-CN method. In a previous contribution, the proposed mixed procedure was evaluated on 100 observed events showing encouraging results. In this study, a sensitivity analysis is carried out to further explore the feasibility of applying the CN4GA tool in small ungauged catchments. The proposed mixed procedure constrains the GA model with boundary and initial conditions so that the GA soil hydraulic parameters are expected to be insensitive toward the net hyetograph peak. To verify and evaluate this behaviour, synthetic design hyetograph and synthetic rainfall time series are selected and used in a Monte Carlo analysis. The results are encouraging and confirm that the parameter variability makes the proposed method an appropriate tool for hydrologic predictions in ungauged catchments. Keywords: SCS-CN method, Green-Ampt method, rainfall excess, ungauged basins, design hydrograph, rainfall-runoff modelling.

  7. Self-adaptive Green-Ampt infiltration parameters obtained from measured moisture processes

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    Long Xiang

    2016-07-01

    Full Text Available The Green-Ampt (G-A infiltration model (i.e., the G-A model is often used to characterize the infiltration process in hydrology. The parameters of the G-A model are critical in applications for the prediction of infiltration and associated rainfall-runoff processes. Previous approaches to determining the G-A parameters have depended on pedotransfer functions (PTFs or estimates from experimental results, usually without providing optimum values. In this study, rainfall simulators with soil moisture measurements were used to generate rainfall in various experimental plots. Observed runoff data and soil moisture dynamic data were jointly used to yield the infiltration processes, and an improved self-adaptive method was used to optimize the G-A parameters for various types of soil under different rainfall conditions. The two G-A parameters, i.e., the effective hydraulic conductivity and the effective capillary drive at the wetting front, were determined simultaneously to describe the relationships between rainfall, runoff, and infiltration processes. Through a designed experiment, the method for determining the G-A parameters was proved to be reliable in reflecting the effects of pedologic background in G-A type infiltration cases and deriving the optimum G-A parameters. Unlike PTF methods, this approach estimates the G-A parameters directly from infiltration curves obtained from rainfall simulation experiments so that it can be used to determine site-specific parameters. This study provides a self-adaptive method of optimizing the G-A parameters through designed field experiments. The parameters derived from field-measured rainfall-infiltration processes are more reliable and applicable to hydrological models.

  8. Equação de green-ampt para a infiltração da água no solo aproximações numéricas para explicitação do volume infiltrado Green-ampt equation for water infiltration into soil numerical approximations to the explicit formulation for the accumulated water

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    Francisco Mercês de Mello

    2008-01-01

    Full Text Available O modelo de infiltração de Green-Ampt (1911, muito utilizado ainda hoje em Hidrologia, não permite explicitar de forma exacta o volume acumulado por infiltração em função do tempo. É neste contexto que se insere o presente estudo ,no qual são propostas duas soluções aproximadas. A primeira equação é original e a segunda resulta de modificações introduzidas numa das equações de Li et al. (1976. Analisaram-se os erros relativos provenientes da aplicação destas equações e apresenta-se um exemplo para melhor concretizar a aplicação destas aproximações numéricas.The Green-Ampt infiltration model (1911, still used in Hydrology nowadays, does not allows to have an exact explicitation of the accumulated infiltration water versus time. The present work tries to solve this problem by presenting two solutions. The first equation is original and the second is the result of some improvements made in one of Li et al equations (1976.The relative errors proceeding from these equation were discussed and one example is presented in order to concretize these numerical applications.

  9. The influence of the net rainfall mixed Curve Number – Green Ampt procedure in flood hazard mapping: a case study in Central Italy

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    Andrea Petroselli

    2013-09-01

    Full Text Available A net rainfall estimation procedure, referred to as Curve-Number For Green-Ampt (CN4GA, combining the Soil Conservation Service - Curve Number (SCS-CN method and the Green and Ampt (GA infiltration equation was recently developed, aiming to distribute at subdaily time resolution the information provided by the SCS-CN method. The initial abstraction and the total volume of rainfall provided by the SCS-CN method are used to identify the ponding time and to quantify the hydraulic conductivity parameter of the GA equation, whereas the GA infiltration model distributes the total volume of the rainfall excess provided by the SCS-CN method. In this study we evaluate the proposed procedure with reference to a real case comparing the flood mapping obtained applying the event-based approach for two different net rainfall scenarios: the proposed CN4GA and the common SCS-CN. Results underline that the net rainfall estimation step can affect the final flood mapping result.

  10. Substituição dos parâmetros do modelo de Green-Ampt-Mein-Larson para estimativa da infiltração em alguns solos do Brasil Adjustment of Green-Ampt-Mein-Larson parameters to predict infiltration in some Brazilian soils

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    Roberto Avelino Cecílio

    2007-10-01

    Full Text Available A partir de uma análise detalhada do processo de infiltração de água no solo, foram propostas alternativas para adequação dos parâmetros de entrada do modelo de Green-Ampt-Mein-Larson (GAML, na tentativa de melhorar a eficiência da estimativa da infiltração em alguns solos brasileiros. As adequações consistiram em substituir a condutividade hidráulica do solo saturado (K0 pela taxa de infiltração estável (Tie e o teor de água do solo saturado (q s pelo teor de água na zona de transmissão (q w, além de estabelecer uma equação para estimativa do potencial matricial na frente de umedecimento (y f com base nos parâmetros do modelo de curva de retenção de água de Brooks & Corey. Avaliou-se o desempenho do conjunto de adequações propostas (GAML-t para estimativa da infiltração de água em três solos: Latossolo Vermelho-Amarelo, Latossolo Vermelho e Argissolo Vermelho. O desempenho do GAML-t foi comparado com o obtido pelo GAML aplicado em sua forma original e adequado segundo cinco diferentes formas, evidenciando-se que o primeiro obteve melhor desempenho nos três solos estudados.Based on a detailed analysis of the process of water infiltration into the soil, an alternative is proposed to adjust the input parameters of the Green-Ampt-Mein-Larson (GAML model to optimize infiltration estimates of some Brazilian soils. The adjustments consisted of the replacement of the parameters saturated hydraulic conductivity (K0 by stable infiltration rate (Tie and soil moisture saturation (q s by water content in the transmission zone (q w. Moreover, an equation was established to estimate the matric potencial at the wetting front (y f, based on the parameters of the water retention curve of Brooks and Corey. The performance of the set of proposed adjustments (GAML-t was evaluated for the estimation of water infiltration in three soil types. The performance of GAML-t was compared with the original GAML and adjusted to five different

  11. The influence of the net rainfall mixed Curve Number – Green Ampt procedure in flood hazard mapping: a case study in Central Italy

    OpenAIRE

    Andrea Petroselli; Ettore Arcangeletti; Elena Allegrini; Nunzio Romano; Salvatore Grimaldi

    2013-01-01

    A net rainfall estimation procedure, referred to as Curve-Number For Green-Ampt (CN4GA), combining the Soil Conservation Service - Curve Number (SCS-CN) method and the Green and Ampt (GA) infiltration equation was recently developed, aiming to distribute at subdaily time resolution the information provided by the SCS-CN method. The initial abstraction and the total volume of rainfall provided by the SCS-CN method are used to identify the ponding time and to quantify the hydraulic conductivity...

  12. A modified hydrodynamic model for routing unsteady flow in a river having piedmont zone

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    Patowary Sudarshan

    2017-03-01

    Full Text Available Existence of piedmont zone in a river bed is a critical parameter from among numerous variations of topographical, geological and geographical conditions that can significantly influence the river flow scenario. Downstream flow situation assessed by routing of upstream hydrograph may yield higher flow depth if existence of such high infiltration zone is ignored and therefore it is a matter of concern for water resources planning and flood management. This work proposes a novel modified hydrodynamic model that has the potential to accurately determine the flow scenario in presence of piedmont zone. The model has been developed using unsteady free surface flow equations, coupled with Green-Ampt infiltration equation as governing equation. For solution of the governing equations Beam and Warming implicit finite difference scheme has been used. The proposed model was first validated from the field data of Trout Creek River showing excellent agreement. The validated model was then applied to a hypothetical river reach commensurate with the size of major tributaries of Brahmaputra Basin of India. Results indicated a 10% and 14% difference in the maximum value of discharge and depth hydrograph in presence and absence of piedmont zone respectively. Overall this model was successfully used to accurately predict the effect of piedmont zone on the unsteady flow in a river.

  13. Comparison of infiltration models in NIT Kurukshetra campus

    Science.gov (United States)

    Singh, Balraj; Sihag, Parveen; Singh, Karan

    2018-05-01

    The aim of the present investigation is to evaluate the performance of infiltration models used to calculate the infiltration rate of the soils. Ten different locations were chosen to measure the infiltration rate in NIT Kurukshetra. The instrument used for the experimentation was double ring infiltrometer. Some of the popular infiltration models like Horton's, Philip's, Modified Philip's and Green-Ampt were fitted with infiltration test data and performance of the models was determined using Nash-Sutcliffe efficiency (NSE), coefficient of correlation (C.C) and Root mean square error (RMSE) criteria. The result suggests that Modified Philip's model is the most accurate model where values of C.C, NSE and RMSE vary from 0.9947-0.9999, 0.9877-0.9998 to 0.1402-0.6913 (mm/h), respectively. Thus, this model can be used to synthetically produce infiltration data in the absence of infiltration data under the same conditions.

  14. Distinguishing modified gravity models

    International Nuclear Information System (INIS)

    Brax, Philippe; Davis, Anne-Christine

    2015-01-01

    Modified gravity models with screening in local environments appear in three different guises: chameleon, K-mouflage and Vainshtein mechanisms. We propose to look for differences between these classes of models by considering cosmological observations at low redshift. In particular, we analyse the redshift dependence of the fine structure constant and the proton to electron mass ratio in each of these scenarios. When the absorption lines belong to unscreened regions of space such as dwarf galaxies, a time variation would be present for chameleons. For both K-mouflage and Vainshtein mechanisms, the cosmological time variation of the scalar field is not suppressed in both unscreened and screened environments, therefore enhancing the variation of constants and their detection prospect. We also consider the time variation of the redshift of distant objects using their spectrocopic velocities. We find that models of the K-mouflage and Vainshtein types have very different spectroscopic velocities as a function of redshift and that their differences with the Λ-CDM template should be within reach of the future ELT-HIRES observations

  15. Distinguishing modified gravity models

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [Institut de Physique Théorique, Université Paris-Saclay, CEA, CNRS, F-91191 Gif/Yvette Cedex (France); Davis, Anne-Christine, E-mail: philippe.brax@cea.fr, E-mail: A.C.Davis@damtp.cam.ac.uk [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Cambridge, CB3 0WA (United Kingdom)

    2015-10-01

    Modified gravity models with screening in local environments appear in three different guises: chameleon, K-mouflage and Vainshtein mechanisms. We propose to look for differences between these classes of models by considering cosmological observations at low redshift. In particular, we analyse the redshift dependence of the fine structure constant and the proton to electron mass ratio in each of these scenarios. When the absorption lines belong to unscreened regions of space such as dwarf galaxies, a time variation would be present for chameleons. For both K-mouflage and Vainshtein mechanisms, the cosmological time variation of the scalar field is not suppressed in both unscreened and screened environments, therefore enhancing the variation of constants and their detection prospect. We also consider the time variation of the redshift of distant objects using their spectrocopic velocities. We find that models of the K-mouflage and Vainshtein types have very different spectroscopic velocities as a function of redshift and that their differences with the Λ-CDM template should be within reach of the future ELT-HIRES observations.

  16. Modelagem hidrológica em microbacia hidrográfica parte II: teste do modelo HidroBacia Hydrologic modeling of a small watershed part II: HidroBacia model test

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    Sidney S. Zanetti

    2009-08-01

    Full Text Available Este trabalho consistiu na modelagem hidrológica de uma microbacia hidrográfica utilizando-se o modelo HidroBacia, no qual o processo de infiltração da água no solo é representado por meio da equação de Green-Ampt modificada por Mein e Larson. Obtiveram-se, dentre os parâmetros desta equação, o potencial matricial na frente de umedecimento, a condutividade hidráulica e a umidade do solo na zona de transmissão, através de diversos métodos apresentados na literatura; desta forma, foram preparadas e testadas 36 combinações de dados de entrada, visando identificar as que apresentam melhor desempenho nas simulações do hidrograma de escoamento superficial com o modelo e se selecionaram, dentre os eventos de chuva-vazão registrados na microbacia, os 14 mais relevantes para realização das simulações. Das 36 combinações de dados de entrada testadas, seis apresentaram melhor desempenho na estimação dos hidrogramas. O modelo HidroBacia ainda necessita de aprimoramentos, juntamente com análises de sensibilidade, com vista a identificar possíveis incompatibilidades entre os dados de entrada e os respectivos resultados das simulações, uma vez que o modelo apresentou resultados incoerentes em determinadas situações.This work consisted of the hydrologic modeling of a small watershed using the HidroBacia model. The soil water infiltration process is represented by means of the Green-Ampt equation, modified by Mein and Larson, in this model. Among the equation parameters, matric potential in the wetting front, hydraulic conductivity and soil moisture in the "field saturation" were obtained using different methods based on previous scientific literature. Thirty six input data combinations were tested in order to identify those that showed better performance on the runoff hydrograph simulations with the model. Between the rainfall-runoff events registered on watershed, the most relevant (14 of them were selected to perform the

  17. Sensitivity analysis of a modified energy model

    International Nuclear Information System (INIS)

    Suganthi, L.; Jagadeesan, T.R.

    1997-01-01

    Sensitivity analysis is carried out to validate model formulation. A modified model has been developed to predict the future energy requirement of coal, oil and electricity, considering price, income, technological and environmental factors. The impact and sensitivity of the independent variables on the dependent variable are analysed. The error distribution pattern in the modified model as compared to a conventional time series model indicated the absence of clusters. The residual plot of the modified model showed no distinct pattern of variation. The percentage variation of error in the conventional time series model for coal and oil ranges from -20% to +20%, while for electricity it ranges from -80% to +20%. However, in the case of the modified model the percentage variation in error is greatly reduced - for coal it ranges from -0.25% to +0.15%, for oil -0.6% to +0.6% and for electricity it ranges from -10% to +10%. The upper and lower limit consumption levels at 95% confidence is determined. The consumption at varying percentage changes in price and population are analysed. The gap between the modified model predictions at varying percentage changes in price and population over the years from 1990 to 2001 is found to be increasing. This is because of the increasing rate of energy consumption over the years and also the confidence level decreases as the projection is made far into the future. (author)

  18. Modeling rainfall infiltration on hillslopes using Flux-concentration relation and time compression approximation

    Science.gov (United States)

    Wang, Jie; Chen, Li; Yu, Zhongbo

    2018-02-01

    Rainfall infiltration on hillslopes is an important issue in hydrology, which is related to many environmental problems, such as flood, soil erosion, and nutrient and contaminant transport. This study aimed to improve the quantification of infiltration on hillslopes under both steady and unsteady rainfalls. Starting from Darcy's law, an analytical integral infiltrability equation was derived for hillslope infiltration by use of the flux-concentration relation. Based on this equation, a simple scaling relation linking the infiltration times on hillslopes and horizontal planes was obtained which is applicable for both small and large times and can be used to simplify the solution procedure of hillslope infiltration. The infiltrability equation also improved the estimation of ponding time for infiltration under rainfall conditions. For infiltration after ponding, the time compression approximation (TCA) was applied together with the infiltrability equation. To improve the computational efficiency, the analytical integral infiltrability equation was approximated with a two-term power-like function by nonlinear regression. Procedures of applying this approach to both steady and unsteady rainfall conditions were proposed. To evaluate the performance of the new approach, it was compared with the Green-Ampt model for sloping surfaces by Chen and Young (2006) and Richards' equation. The proposed model outperformed the sloping Green-Ampt, and both ponding time and infiltration predictions agreed well with the solutions of Richards' equation for various soil textures, slope angles, initial water contents, and rainfall intensities for both steady and unsteady rainfalls.

  19. Systematic simulations of modified gravity: chameleon models

    International Nuclear Information System (INIS)

    Brax, Philippe; Davis, Anne-Christine; Li, Baojiu; Winther, Hans A.; Zhao, Gong-Bo

    2013-01-01

    In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have modified the N-body simulation code ecosmog to perform a total of 65 simulations for different models and parameter values, including the default ΛCDM. These simulations enable us to explore a significant portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the ΛCDM paradigm cannot be reproduced by a linear analysis even on scales as large as k ∼ 0.05 hMpc −1 , since the latter incorrectly assumes that the modification of gravity depends only on the background matter density. Our results show that the chameleon screening mechanism is significantly more efficient than other mechanisms such as the dilaton and symmetron, especially in high-density regions and at early times, and can serve as a guidance to determine the parts of the chameleon parameter space which are cosmologically interesting and thus merit further studies in the future

  20. Systematic simulations of modified gravity: chameleon models

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [Institut de Physique Theorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Davis, Anne-Christine [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Li, Baojiu [Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Winther, Hans A. [Institute of Theoretical Astrophysics, University of Oslo, 0315 Oslo (Norway); Zhao, Gong-Bo, E-mail: philippe.brax@cea.fr, E-mail: a.c.davis@damtp.cam.ac.uk, E-mail: baojiu.li@durham.ac.uk, E-mail: h.a.winther@astro.uio.no, E-mail: gong-bo.zhao@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom)

    2013-04-01

    In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have modified the N-body simulation code ecosmog to perform a total of 65 simulations for different models and parameter values, including the default ΛCDM. These simulations enable us to explore a significant portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the ΛCDM paradigm cannot be reproduced by a linear analysis even on scales as large as k ∼ 0.05 hMpc{sup −1}, since the latter incorrectly assumes that the modification of gravity depends only on the background matter density. Our results show that the chameleon screening mechanism is significantly more efficient than other mechanisms such as the dilaton and symmetron, especially in high-density regions and at early times, and can serve as a guidance to determine the parts of the chameleon parameter space which are cosmologically interesting and thus merit further studies in the future.

  1. Application of hydrological model HidroBacia in Jaqueira stream watershed, Espírito SantoAplicação do modelo HidroBacia na microbacia do córrego Jaqueira, Espírito Santo

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    Roberto Avelino Cecílio

    2013-10-01

    Full Text Available Hydrologic simulation of watersheds is an useful tool for the water resources management and to reduce environmental degradation in watersheds. This work evaluated the applicability of the hydrologic modeling in a small watershed using the HidroBacia model at Alegre-ES and compare the results of flow maximum (Qmáx and surface runoff flow (LES in watershed “outlet” with rational methods (MR and Curve Number (MNC. The soil water infiltration process is represented by means of the Green-Ampt equation, modified by Mein and Larson (GAML in this model. This equation needs the parameters: matric potential in the wetting front, hydraulic conductivity and soil moisture in the “field saturation”. This work assessed seventy two input combinations of parameters for equation GAML. Compared to real data (obtained at the watershed “outlet” the Qmáx and LES with the simulated by HidroBacia and by the MR and MNC. Verify in this work seven best combinations estimated Qmáx and LES in simulations with HidroBacia. The simulated data by the MR and MNC overestimated Qmáx and LES, respectively. Therefore, for experimental condition, recommend the use of hydrological model HidroBacia to estimate both parameters the Qmáx and the LES. A modelagem hidrológica aplicada em bacias hidrográficas consiste numa das principais ferramentas para a gestão dos recursos hídricos, visando minimizar o processo de degradação ambiental. O presente trabalho objetivou avaliar a aplicabilidade do modelo hidrológico HidroBacia em uma microbacia hidrográfica de Alegre-ES, além de compará-lo com os métodos Racional (MR e Número da Curva (MNC. O processo de infiltração de água no solo no HidroBacia, representado pela equação de Green- Ampt-Mein-Larson (GAML, foi simulado por meio de 72 diferentes combinações de parâmetros de entrada, a fim de evidenciar a de melhor desempenho. Compararam-se dados reais (obtidos no exutório da microbacia de vazão máxima de

  2. Model to support the evaluation of the impact of the use and management of the soil on the water balance=Modelo de suporte à avaliação do impacto do uso e manejo do solo no balanço hídrico

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    Gleiph Ghiotto Menezes

    2012-10-01

    Full Text Available The purpose of this work was to develop a hydrological model for the simulation of the water balance in agricultural areas. The model uses a double exponential equation to represent the rainfall profile and uses the Green-Ampt-Mein-Larson equation to estimate the soil water infiltration rate. To evaluate the model, monthly and yearly rainfall and runoff data were obtained from four experimental plots located at the State University of Santa Catarina, UDESC, in the period from 2003 to 2008. The four treatments were bare soil (BS, conventional tillage (CT, minimum tillage (MT and no-tillage (NT. The simulation was carried out using two synthetic rainfall series, one adjusted on a monthly basis (SAMB and the other adjusted on a daily basis (SADB. The parameters for the Green-Amp equation modified by Mein-Larson (GAML were adjusted, and the best combination was found to be the replacement of the saturated hydraulic conductivity (K by the constant infiltration rate (fc and the estimation of the wetting front head pressure as a function of the hydraulic conductivity in the saturation zone (ψ(Kw. There was not a significant difference between the observed annual mean runoff and the annual mean runoff estimated by the model.O objetivo deste trabalho foi desenvolver um modelo hidrológico para a simulação do balanço hídrico em áreas agrícolas. O modelo utiliza uma função dupla-exponencial para representar o perfil de precipitação, e a equação de Green-Ampt modificada por Mein-Larson (GAML para estimar a taxa de infiltração de água no solo. Para a avaliação do modelo foram utilizados dados mensais e anuais de precipitação e escoamento superficial obtidos de quatro parcelas experimentais lozalizadas no campus da Universidade do Estado de Santa Catarina – UDESC, no período de 2003 a 2008. Os tratamentos foram o solo sem cultivo (BS, o preparo convencional (CT, o cultivo mínimo (MT e a semeadura direta (NT. A simulação foi realizada

  3. Terrestrial Sagnac delay constraining modified gravity models

    Science.gov (United States)

    Karimov, R. Kh.; Izmailov, R. N.; Potapov, A. A.; Nandi, K. K.

    2018-04-01

    Modified gravity theories include f(R)-gravity models that are usually constrained by the cosmological evolutionary scenario. However, it has been recently shown that they can also be constrained by the signatures of accretion disk around constant Ricci curvature Kerr-f(R0) stellar sized black holes. Our aim here is to use another experimental fact, viz., the terrestrial Sagnac delay to constrain the parameters of specific f(R)-gravity prescriptions. We shall assume that a Kerr-f(R0) solution asymptotically describes Earth's weak gravity near its surface. In this spacetime, we shall study oppositely directed light beams from source/observer moving on non-geodesic and geodesic circular trajectories and calculate the time gap, when the beams re-unite. We obtain the exact time gap called Sagnac delay in both cases and expand it to show how the flat space value is corrected by the Ricci curvature, the mass and the spin of the gravitating source. Under the assumption that the magnitude of corrections are of the order of residual uncertainties in the delay measurement, we derive the allowed intervals for Ricci curvature. We conclude that the terrestrial Sagnac delay can be used to constrain the parameters of specific f(R) prescriptions. Despite using the weak field gravity near Earth's surface, it turns out that the model parameter ranges still remain the same as those obtained from the strong field accretion disk phenomenon.

  4. Equivalence principle implications of modified gravity models

    International Nuclear Information System (INIS)

    Hui, Lam; Nicolis, Alberto; Stubbs, Christopher W.

    2009-01-01

    Theories that attempt to explain the observed cosmic acceleration by modifying general relativity all introduce a new scalar degree of freedom that is active on large scales, but is screened on small scales to match experiments. We demonstrate that if such screening occurs via the chameleon mechanism, such as in f(R) theory, it is possible to have order unity violation of the equivalence principle, despite the absence of explicit violation in the microscopic action. Namely, extended objects such as galaxies or constituents thereof do not all fall at the same rate. The chameleon mechanism can screen the scalar charge for large objects but not for small ones (large/small is defined by the depth of the gravitational potential and is controlled by the scalar coupling). This leads to order one fluctuations in the ratio of the inertial mass to gravitational mass. We provide derivations in both Einstein and Jordan frames. In Jordan frame, it is no longer true that all objects move on geodesics; only unscreened ones, such as test particles, do. In contrast, if the scalar screening occurs via strong coupling, such as in the Dvali-Gabadadze-Porrati braneworld model, equivalence principle violation occurs at a much reduced level. We propose several observational tests of the chameleon mechanism: 1. small galaxies should accelerate faster than large galaxies, even in environments where dynamical friction is negligible; 2. voids defined by small galaxies would appear larger compared to standard expectations; 3. stars and diffuse gas in small galaxies should have different velocities, even if they are on the same orbits; 4. lensing and dynamical mass estimates should agree for large galaxies but disagree for small ones. We discuss possible pitfalls in some of these tests. The cleanest is the third one where the mass estimate from HI rotational velocity could exceed that from stars by 30% or more. To avoid blanket screening of all objects, the most promising place to look is in

  5. Nuclear matter properties for modified Zimanyi-Moszkowski models

    International Nuclear Information System (INIS)

    Delfino, A.; Coelho, C.T.; Malheiro, M.

    1994-01-01

    Effective Lagrangians involving nucleons coupled to scalar and vector fields are investigated within the framework of relativistic mean-field theory. The study presents the traditional Walecka model and different kinds of scalar derivative coupling suggested by Zimanyi and Moszkowski (ZM). It is shown that the equations of state for all these modified ZM models are soft. The real part of the optical potential for these models is obtained. When compared with the unusual ZM model, the modified models present the peculiarity of giving simultaneously a smaller nucleon effective mass and a smaller incompressibility. This can be explained through the mesonic nonlinear scalar-vector coupling contained in these modified models. (author)

  6. Turing patterns in a modified Lotka-Volterra model

    International Nuclear Information System (INIS)

    McGehee, Edward A.; Peacock-Lopez, Enrique

    2005-01-01

    In this Letter we consider a modified Lotka-Volterra model widely known as the Bazykin model, which is the MacArthur-Rosenzweig (MR) model that includes a prey-dependent response function and is modified with the inclusion of intraspecies interactions. We show that a quadratic intra-prey interaction term, which is the most realistic nonlinearity, yields sufficient conditions for Turing patterns. For the Bazykin model we find the Turing region in parameter space and Turing patterns in one dimension

  7. Hydraulic Model Tests on Modified Wave Dragon

    DEFF Research Database (Denmark)

    Hald, Tue; Lynggaard, Jakob

    A floating model of the Wave Dragon (WD) was built in autumn 1998 by the Danish Maritime Institute in scale 1:50, see Sørensen and Friis-Madsen (1999) for reference. This model was subjected to a series of model tests and subsequent modifications at Aalborg University and in the following...... are found in Hald and Lynggaard (2001). Model tests and reconstruction are carried out during the phase 3 project: ”Wave Dragon. Reconstruction of an existing model in scale 1:50 and sequentiel tests of changes to the model geometry and mass distribution parameters” sponsored by the Danish Energy Agency...

  8. New classes of modified teleparallel gravity models

    Science.gov (United States)

    Bahamonde, Sebastian; Böhmer, Christian G.; Krššák, Martin

    2017-12-01

    New classes of modified teleparallel theories of gravity are introduced. The action of this theory is constructed to be a function of the irreducible parts of torsion f (Tax ,Tten ,Tvec), where Tax ,Tten and Tvec are squares of the axial, tensor and vector components of torsion, respectively. This is the most general (well-motivated) second order teleparallel theory of gravity that can be constructed from the torsion tensor. Different particular second order theories can be recovered from this theory such as new general relativity, conformal teleparallel gravity or f (T) gravity. Additionally, the boundary term B which connects the Ricci scalar with the torsion scalar via R = - T + B can also be incorporated into the action. By performing a conformal transformation, it is shown that the two unique theories which have an Einstein frame are either the teleparallel equivalent of general relativity or f (- T + B) = f (R) gravity, as expected.

  9. Modeling and Simulation of a Modified Quadruple Tank System

    DEFF Research Database (Denmark)

    Mohd. Azam, Sazuan Nazrah; Jørgensen, John Bagterp

    2015-01-01

    to model and control. In this paper, a modified quadruple-tank system has been described, all the important variables has been outlined and a mathematical model has been presented. We developed deterministic and stochastic models using differential equations and simulate the models using Matlab...

  10. Plural Governance: A Modified Transaction Cost Model

    DEFF Research Database (Denmark)

    Mols, Niels Peter; Menard, Claude

    2014-01-01

    Plural governance is a form of governance where a firm both makes and buys similar goods or services. Despite a widespread use of plural governance there are no transaction cost models of how plural governance affects performance. This paper reviews the literature about plural forms and proposes...... a model relating transaction cost and resource-based variables to the cost of the plural form. The model is then used to analyze when the plural form is efficient compared to alternative governance structures. We also use the model to discuss the strength of three plural form synergies....

  11. Mouse models for atherosclerosis and pharmaceutical modifiers

    NARCIS (Netherlands)

    Zadelaar, A.S.M.; Kleemann, R.; Verschuren, L.; Vries-van der Weij, J. de; Hoorn, J. van der; Princen, H.M.; Kooistra, T.

    2007-01-01

    Atherosclerosis is a multifactorial highly-complex disease with numerous etiologies that work synergistically to promote lesion development. The ability to develop preventive and ameliorative treatments will depend on animal models that mimic the human subject metabolically and pathophysiologically

  12. Static properties of nucleons in a modified Skyrme model

    International Nuclear Information System (INIS)

    Nguyen Ai Viet; Pham Thuc Tuyen

    1989-02-01

    A modified Skyrme type model is proposed by neglecting non-linearly non-invariant terms from the Skyrme's Lagrangian. It turns out that beside some additional advantages a hedgehog configuration of this model can quantitatively describe nucleons the same way as the skyrmion does in the usual Skyrme model. (author) 8 refs.; 2 figs

  13. Modified Invasion Percolation Models for Multiphase Processes

    Energy Technology Data Exchange (ETDEWEB)

    Karpyn, Zuleima [Pennsylvania State Univ., State College, PA (United States)

    2015-01-31

    This project extends current understanding and modeling capabilities of pore-scale multiphase flow physics in porous media. High-resolution X-ray computed tomography imaging experiments are used to investigate structural and surface properties of the medium that influence immiscible displacement. Using experimental and computational tools, we investigate the impact of wetting characteristics, as well as radial and axial loading conditions, on the development of percolation pathways, residual phase trapping and fluid-fluid interfacial areas.

  14. A Modified Microfinance Model Proposed for the United States

    Directory of Open Access Journals (Sweden)

    Eldon H Bernstein

    2014-07-01

    While the goal in the traditional model in developing markets is the elimination of poverty, we show how those critical conditions help to explain the lack of success in the United States.  We propose a modified model whose goal is the creation of an entrepreneurial venture or improving the performance of an existing small enterprise.

  15. Systematic simulations of modified gravity: symmetron and dilaton models

    International Nuclear Information System (INIS)

    Brax, Philippe; Davis, Anne-Christine; Li, Baojiu; Winther, Hans A.; Zhao, Gong-Bo

    2012-01-01

    We study the linear and nonlinear structure formation in the dilaton and symmetron models of modified gravity using a generic parameterisation which describes a large class of scenarios using only a few parameters, such as the coupling between the scalar field and the matter, and the range of the scalar force on very large scales. For this we have modified the N-body simulation code ECOSMOG, which is a variant of RAMSES working in modified gravity scenarios, to perform a set of 110 simulations for different models and parameter values, including the default ΛCDM. These simulations enable us to explore a large portion of the parameter space. We have studied the effects of modified gravity on the matter power spectrum and mass function, and found a rich and interesting phenomenology where the difference with the ΛCDM template cannot be reproduced by a linear analysis even on scales as large as k ∼ 0.05 hMpc −1 . Our results show the full effect of screening on nonlinear structure formation and the associated deviation from ΛCDM. We also investigate how differences in the force mediated by the scalar field in modified gravity models lead to qualitatively different features for the nonlinear power spectrum and the halo mass function, and how varying the individual model parameters changes these observables. The differences are particularly large in the nonlinear power spectra whose shapes for f(R), dilaton and symmetron models vary greatly, and where the characteristic bump around 1 hMpc −1 of f(R) models is preserved for symmetrons, whereas an increase on much smaller scales is particular to symmetrons. No bump is present for dilatons where a flattening of the power spectrum takes place on small scales. These deviations from ΛCDM and the differences between modified gravity models, such as dilatons and symmetrons, could be tested with future surveys

  16. ENU mutagenesis to generate genetically modified rat models.

    Science.gov (United States)

    van Boxtel, Ruben; Gould, Michael N; Cuppen, Edwin; Smits, Bart M G

    2010-01-01

    The rat is one of the most preferred model organisms in biomedical research and has been extremely useful for linking physiology and pathology to the genome. However, approaches to genetically modify specific genes in the rat germ line remain relatively scarce. To date, the most efficient approach for generating genetically modified rats has been the target-selected N-ethyl-N-nitrosourea (ENU) mutagenesis-based technology. Here, we describe the detailed protocols for ENU mutagenesis and mutant retrieval in the rat model organism.

  17. Document Categorization with Modified Statistical Language Models for Agglutinative Languages

    Directory of Open Access Journals (Sweden)

    Tantug

    2010-11-01

    Full Text Available In this paper, we investigate the document categorization task with statistical language models. Our study mainly focuses on categorization of documents in agglutinative languages. Due to the productive morphology of agglutinative languages, the number of word forms encountered in naturally occurring text is very large. From the language modeling perspective, a large vocabulary results in serious data sparseness problems. In order to cope with this drawback, previous studies in various application areas suggest modified language models based on different morphological units. It is reported that performance improvements can be achieved with these modified language models. In our document categorization experiments, we use standard word form based language models as well as other modified language models based on root words, root words and part-of-speech information, truncated word forms and character sequences. Additionally, to find an optimum parameter set, multiple tests are carried out with different language model orders and smoothing methods. Similar to previous studies on other tasks, our experimental results on categorization of Turkish documents reveal that applying linguistic preprocessing steps for language modeling provides improvements over standard language models to some extent. However, it is also observed that similar level of performance improvements can also be acquired by simpler character level or truncated word form models which are language independent.

  18. Study on radiation modifiers with zebrafish as a vertebrate model

    International Nuclear Information System (INIS)

    Lei Jixiao; Ni Jin; Cai Jianming; Shen Jianliang

    2010-01-01

    Zebrafish (Danio rerio) as a vertebrate model system has been used in a series of biomedical experiments by scientists. It offers distinctive benefits as a laboratory model system, especially for embryonic development, gene expression, drug screening and human disease model. In this paper, the typical radiation modifiers, such as Amifostine, DF-1, AG1478, Flavopiridol and DNA repair proteins involved in biomedical process by use of zebrafish have been reviewed. (authors)

  19. MODELLING OF KINETICS OF FLUORINE ADSORPTION ONTO MODIFIED DIATOMITE

    Directory of Open Access Journals (Sweden)

    VEACESLAV ZELENTSOV

    2017-03-01

    Full Text Available The paper presents kinetics modelling of adsorption of fluorine onto modified diatomite, its fundamental characteristics and mathematical derivations. Three models of defluoridation kinetics were used to fit the experimental results on adsorption fluorine onto diatomite: the pseudo-first order model Lagergren, the pseudo-second order model G. McKay and H.S. Ho and intraparticle diffusion model of W.J. Weber and J.C. Morris. Kinetics studies revealed that the adsorption of fluorine followed second-order rate model, complimented by intraparticle diffusion kinetics. The adsorption mechanism of fluorine involved three stages – external surface adsorption, intraparticle diffusion and the stage of equilibrium.

  20. Impacts of Different Soil Texture and Organic Content on Hydrological Performance of Bioretention

    Science.gov (United States)

    Gülbaz, Sezar; Melek Kazezyilmaz Alhan, Cevza

    2015-04-01

    reduction and arrival time and shape of the hydrograph. iii) A mathematical representation of the relation among the rainfall, surface runoff over the watershed and outflow from the bioretention is developed by incorporating kinematic wave equation into the modified Green-Ampt Method. The rainfall intensity in modified Green-Ampt method is represented by the inflow per unit surface area of bioretention which may be obtained from kinematic wave solution using the measured rainfall data. Variable rainfall cases may be taken into account by using the modified Green-Ampt method. Thus, employing the modified Green-Ampt method helps significantly in understanding and explaining the hydrological mechanism of a bioretention cell where the Darcy law or the classical Green-Ampt method is inadequate which works under constant rainfall intensities. Consequently, the rainfall is directly related with the outflow through the bioretention. This study discusses only the water quantity of bioretention.

  1. Anterior EEG Asymmetry and the Modifier Model of Autism

    Science.gov (United States)

    Burnette, Courtney P.; Henderson, Heather A.; Inge, Anne Pradella; Zahka, Nicole E.; Schwartz, Caley B.; Mundy, Peter C.

    2011-01-01

    Individual differences in the expression of autism complicate research on the nature and treatment of this disorder. In the Modifier Model of Autism (Mundy et al. 2007), we proposed that individual differences in autism may result not only from syndrome specific causal processes, but also from variability in generic, non-syndrome specific…

  2. ENU mutagenesis to generate genetically modified rat models

    NARCIS (Netherlands)

    van Boxtel, R.; Gould, M.; Cuppen, E.; Smits, B.M.

    2010-01-01

    The rat is one of the most preferred model organisms in biomedical research and has been extremely useful for linking physiology and pathology to the genome. However, approaches to genetically modify specific genes in the rat germ line remain relatively scarce. To date, the most efficient approach

  3. Frequency behaviour of the modified Jiles-Atherton model

    International Nuclear Information System (INIS)

    Chwastek, Krzysztof

    2008-01-01

    In the paper the behaviour of the recently modified Jiles-Atherton model of hysteresis under a distorted magnetization pattern is examined. The modification is aimed at improving the modelling of reversible processes. The equation for anhysteretic model is replaced from Langevin function to the more general Brillouin function. The structure of model equation is similar to that of the product Preisach model. The dynamic effects are taken into account in the description by the introduction of the lagged response with respect to the input

  4. Modified Regression Correlation Coefficient for Poisson Regression Model

    Science.gov (United States)

    Kaengthong, Nattacha; Domthong, Uthumporn

    2017-09-01

    This study gives attention to indicators in predictive power of the Generalized Linear Model (GLM) which are widely used; however, often having some restrictions. We are interested in regression correlation coefficient for a Poisson regression model. This is a measure of predictive power, and defined by the relationship between the dependent variable (Y) and the expected value of the dependent variable given the independent variables [E(Y|X)] for the Poisson regression model. The dependent variable is distributed as Poisson. The purpose of this research was modifying regression correlation coefficient for Poisson regression model. We also compare the proposed modified regression correlation coefficient with the traditional regression correlation coefficient in the case of two or more independent variables, and having multicollinearity in independent variables. The result shows that the proposed regression correlation coefficient is better than the traditional regression correlation coefficient based on Bias and the Root Mean Square Error (RMSE).

  5. Usage of Modified Heuristic Model for Determination of Software Stability

    Directory of Open Access Journals (Sweden)

    Sergey Konstantinovich Marfenko

    2013-02-01

    Full Text Available The subject of this paper is analysis method for determining the stability of software against the attacks on its integrity. It is suggested to use the modified heuristic model of software reliability as mathematic basis of this method. This model is based on classic approach, but it takes into account impact levels of different software errors on system integrity. It allows to define critical characteristics of software: percentage of time in stable working, the possibility of failure.

  6. A modified discrete element model for sea ice dynamics

    Institute of Scientific and Technical Information of China (English)

    LI Baohui; LI Hai; LIU Yu; WANG Anliang; JI Shunying

    2014-01-01

    Considering the discontinuous characteristics of sea ice on various scales, a modified discrete element mod-el (DEM) for sea ice dynamics is developed based on the granular material rheology. In this modified DEM, a soft sea ice particle element is introduced as a self-adjustive particle size function. Each ice particle can be treated as an assembly of ice floes, with its concentration and thickness changing to variable sizes un-der the conservation of mass. In this model, the contact forces among ice particles are calculated using a viscous-elastic-plastic model, while the maximum shear forces are described with the Mohr-Coulomb fric-tion law. With this modified DEM, the ice flow dynamics is simulated under the drags of wind and current in a channel of various widths. The thicknesses, concentrations and velocities of ice particles are obtained, and then reasonable dynamic process is analyzed. The sea ice dynamic process is also simulated in a vortex wind field. Taking the influence of thermodynamics into account, this modified DEM will be improved in the future work.

  7. Modified Mathematical Model For Neutralization System In Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Ahmmed Saadi Ibrehem

    2011-05-01

    Full Text Available A modified model for the neutralization process of Stirred Tank Reactors (CSTR reactor is presented in this study. The model accounts for the effect of strong acid [HCL] flowrate and strong base [NaOH] flowrate with the ionic concentrations of [Cl-] and [Na+] on the Ph of the system. In this work, the effect of important reactor parameters such as ionic concentrations and acid and base flowrates on the dynamic behavior of the CSTR is investigated and the behavior of mathematical model is compared with the reported models for the McAvoy model and Jutila model. Moreover, the results of the model are compared with the experimental data in terms of pH dynamic study. A good agreement is observed between our model prediction and the actual plant data. © 2011 BCREC UNDIP. All rights reserved(Received: 1st March 2011, Revised: 28th March 2011; Accepted: 7th April 2011[How to Cite: A.S. Ibrehem. (2011. Modified Mathematical Model For Neutralization System In Stirred Tank Reactor. Bulletin of Chemical Reaction Engineering & Catalysis, 6(1: 47-52. doi:10.9767/bcrec.6.1.825.47-52][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.825.47-52 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/825 ] | View in 

  8. Description of Muzzle Blast by Modified Ideal Scaling Models

    Directory of Open Access Journals (Sweden)

    Kevin S. Fansler

    1998-01-01

    Full Text Available Gun blast data from a large variety of weapons are scaled and presented for both the instantaneous energy release and the constant energy deposition rate models. For both ideal explosion models, similar amounts of data scatter occur for the peak overpressure but the instantaneous energy release model correlated the impulse data significantly better, particularly for the region in front of the gun. Two parameters that characterize gun blast are used in conjunction with the ideal scaling models to improve the data correlation. The gun-emptying parameter works particularly well with the instantaneous energy release model to improve data correlation. In particular, the impulse, especially in the forward direction of the gun, is correlated significantly better using the instantaneous energy release model coupled with the use of the gun-emptying parameter. The use of the Mach disc location parameter improves the correlation only marginally. A predictive model is obtained from the modified instantaneous energy release correlation.

  9. Bouc–Wen hysteresis model identification using Modified Firefly Algorithm

    International Nuclear Information System (INIS)

    Zaman, Mohammad Asif; Sikder, Urmita

    2015-01-01

    The parameters of Bouc–Wen hysteresis model are identified using a Modified Firefly Algorithm. The proposed algorithm uses dynamic process control parameters to improve its performance. The algorithm is used to find the model parameter values that results in the least amount of error between a set of given data points and points obtained from the Bouc–Wen model. The performance of the algorithm is compared with the performance of conventional Firefly Algorithm, Genetic Algorithm and Differential Evolution algorithm in terms of convergence rate and accuracy. Compared to the other three optimization algorithms, the proposed algorithm is found to have good convergence rate with high degree of accuracy in identifying Bouc–Wen model parameters. Finally, the proposed method is used to find the Bouc–Wen model parameters from experimental data. The obtained model is found to be in good agreement with measured data. - Highlights: • We describe a new method to find the Bouc–Wen hysteresis model parameters. • We propose a Modified Firefly Algorithm. • We compare our method with existing methods to find that the proposed method performs better. • We use our model to fit experimental results. Good agreement is found

  10. Bouc–Wen hysteresis model identification using Modified Firefly Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Zaman, Mohammad Asif, E-mail: zaman@stanford.edu [Department of Electrical Engineering, Stanford University (United States); Sikder, Urmita [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley (United States)

    2015-12-01

    The parameters of Bouc–Wen hysteresis model are identified using a Modified Firefly Algorithm. The proposed algorithm uses dynamic process control parameters to improve its performance. The algorithm is used to find the model parameter values that results in the least amount of error between a set of given data points and points obtained from the Bouc–Wen model. The performance of the algorithm is compared with the performance of conventional Firefly Algorithm, Genetic Algorithm and Differential Evolution algorithm in terms of convergence rate and accuracy. Compared to the other three optimization algorithms, the proposed algorithm is found to have good convergence rate with high degree of accuracy in identifying Bouc–Wen model parameters. Finally, the proposed method is used to find the Bouc–Wen model parameters from experimental data. The obtained model is found to be in good agreement with measured data. - Highlights: • We describe a new method to find the Bouc–Wen hysteresis model parameters. • We propose a Modified Firefly Algorithm. • We compare our method with existing methods to find that the proposed method performs better. • We use our model to fit experimental results. Good agreement is found.

  11. Establishment of modified reversible regional cerebral ischemic models

    International Nuclear Information System (INIS)

    Ji Xunming; Ling Feng; Zhao Xiqing; Xuan Yun; Wang Yueqin; Ling Xiaolan; Chang Hongjun; Zhang Zhiping

    2005-01-01

    Objective: Modifying the method of establishing reversible middle cerebral ischemic models in rats for improvement of the stability and rate of success, so as to raise the reliability of cerebral ischemic study. Methods: Sixty male Wistar rats were randomly divided into two groups, modified and control groups, 30 rats in each group. The method of silicone- tipping on one end of the nylon suture was used to modify the establishment of embolus, and tip-heating method was used to establish the traditional embolus with all the other steps of the procedure just the same. The Zea Longa 5 scoring scale was used to estimate the neurological deficiency while TTC staining method was used to measure and calculate the volume of cerebral infarction. The percentage of successful models with 3-4 grade scorings and the coefficient of the variations of cerebral infarct volume were used to estimate the stability of the models. Results: The rate of success of establishment models in the modification group was significantly higher in comparing with the traditional group (93% vs 60%, χ 2 =9.32, P=0.002). The percentage of model establishment with 3-4 grade neurological scores in modification group was higher than that in the traditional group 96.4% vs 61.2%, χ 2 =9.51, P=0.002). The cerebral infarct volume in modification group and traditional group were (4.1450±0.5019) cm 3 and (3.8435 ± 0.8164) cm 3 , and the coefficients of variation were 12.01% and 21.24% respectively, which indicated that the stability of models was significantly higher in modification group than in the traditional one. Conclusions: The rates of success and stability of the models for reversible focal cerebral ischemia made by the modification method were significantly improved, with decreasing the cost of model creation and increasing the accuracy of study of ischemic cerebral vascular disease. (authors)

  12. Suppression of Spiral Wave in Modified Orengonator Model

    International Nuclear Information System (INIS)

    Ma Jun; Wang Chunni; Jin Wuyin; Yi Ming

    2008-01-01

    In this paper, a spatial perturbation scheme is proposed to suppress the spiral wave in the modified Orengonator model, which is used to describe the chemical reaction in the light-sensitive media. The controllable external illumination Φ is perturbed with a spatial linear function. In our numerical simulation, the scheme is investigated by imposing the external controllable illumination on the space continuously and/or intermittently. The numerical simulation results confirm that the stable rotating spiral wave still can be removed with the scheme proposed in this paper even if the controllable Φ changed vs. time and space synchronously. Then the scheme is also used to control the spiral wave and turbulence in the modified Fitzhugh-Nagumo model. It is found that the scheme is effective to remove the sable rotating and meandering spiral wave but it costs long transient period and intensity of the gradient parameter to eliminate the spiral turbulence

  13. Potentials for the Modified Cam-Clay model

    OpenAIRE

    Zouain , Nestor; Pontes , Ivaldo; Vaunat , Jean

    2009-01-01

    Abstract Energy and dissipation pseudo-potentials are employed to derive constitutive relationships, in the context of thermodynamic concepts, for the widely used Modified Cam-Clay (MCC) model for soil mechanics. A variational formulation of the MCC evolution equations is proposed in this paper. Since plastic collapse of MCC soils cannot be embedded in the classical limit analysis theory, finding the critical amplification of the load that produces plastic collapse is formulated in...

  14. An enhanced Brinson model with modified kinetics for martensite transformation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-Jin; Lee, Jung Ju [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Jeong, Ju-Won [Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Lim, Jae Hyuk [Chonbuk National University, Jeonju (Korea, Republic of)

    2017-03-15

    We propose an enhanced Brinson model with modified kinetics for martensite transformation. Two additional material constants are considered to follow the stress-temperature diagram above austenite start temperature (As) along with treatment to keep the continuity of the martensite volume fraction and the path dependency of the phase transformation. To demonstrate the performance of the proposed model, we implement this algorithm into ABAQUS user subroutine, then conduct several numerical simulations and compare their results with SMA wire experiments as well as those of three-dimensional SMA constitutive models. From the results, it turns out that the proposed model is as accurate as the three-dimensional models and shows better accuracy over original Brinson model in terms of recovery stress.

  15. A discrete model of a modified Burgers' partial differential equation

    Science.gov (United States)

    Mickens, R. E.; Shoosmith, J. N.

    1990-01-01

    A new finite-difference scheme is constructed for a modified Burger's equation. Three special cases of the equation are considered, and the 'exact' difference schemes for the space- and time-independent forms of the equation are presented, along with the diffusion-free case of Burger's equation modeled by a difference equation. The desired difference scheme is then obtained by imposing on any difference model of the initial equation the requirement that, in the appropriate limits, its difference scheme must reduce the results of the obtained equations.

  16. Attractive Casimir effect in an infrared modified gluon bag model

    International Nuclear Information System (INIS)

    Oxman, L.E.; Amaral, R.L.P.G.; Svaiter, N.F.

    2005-01-01

    In this work, we are motivated by previous attempts to derive the vacuum contribution to the bag energy in terms of familiar Casimir energy calculations for spherical geometries. A simple infrared modified model is introduced which allows studying the effects of the analytic structure as well as the geometry in a clear manner. In this context, we show that if a class of infrared vanishing effective gluon propagators is considered, then the renormalized vacuum energy for a spherical bag is attractive, as required by the bag model to adjust hadron spectroscopy

  17. Erosion Modeling Analysis For Modified DWPF SME Tank

    International Nuclear Information System (INIS)

    LEE, SI

    2004-01-01

    In support of an erosion evaluation for the modified cooling coil guide and its supporting structure in the DWPF SME vessel, a computational model was developed to identify potential sites of high erosion using the same methodology established by previous work. The erosion mechanism identified in the previous work was applied to the evaluation of high erosion locations representative of the actual flow process in the modified coil guide of the SME vessel, abrasive erosion which occurs by high wall shear of viscous liquid. The results show that primary locations of the highest erosion due to the abrasive wall erosion are at the leading edge of the guide, external surface of the insert plate, the tank floor next to the insert plate of the coil guide support, and the upstream lead-in plate. The present modeling results show a good comparison between the original and the modified cases in terms of high erosion sites, as well as the degree of erosion and the calculated shear stress. Wall she ar of the tank floor is reduced by about 30 per cent because of the new coil support plate. Calculations for the impeller speed lower than 103 rpm in the SME showed similar erosion patterns but significantly reduced wall shear stresses and reduced overall erosion. Comparisons of the 103 rpm results with SME measurements indicated that no significant erosion of the tank floor in the SME is to be expected. Thus, it is recommended that the agitator speed of SME does not exceed 103 rpm

  18. Ferromagnetism in the Hubbard model: a modified perturbation theory

    International Nuclear Information System (INIS)

    Gangadhar Reddy, G.; Ramakanth, A.; Nolting, W.

    2005-01-01

    We study the possibility of ferromagnetism in the Hubbard model using the modified perturbation theory. In this approach an Ansatz is made for the self-energy of the electron which contains the second order contribution developed around the Hartree-Fock solution and two parameters. The parameters are fixed by using a moment method. This self energy satisfies several known exact limiting cases. Using this self energy, the Curie temperature T c as a function of band filling n is investigated. It is found that T c falls off abruptly as n approaches half filling. The results are in qualitative agreement with earlier calculations using other approximation schemes. (author)

  19. MATHEMATICAL MODEL OF CATALYTIC PROCESSES AT MODIFIED ELECTRODES

    Directory of Open Access Journals (Sweden)

    Femila Mercy Rani Joseph

    Full Text Available A mathematical modeling of electrocatalytic processes taking place at modified electrodes is discussed. In this paper we obtained the approximate analytical solutions for the nonlinear equations under non steady state conditions using homotopy perturbation method. Simple and approximate polynomial expressions for the concentration of reactant, product and charge carrier were obtained in terms of diffusion coefficient and rate constant. In this work the numerical simulation of the problem is reported using Scilab program. In this manuscript analytical results are compared with simulation results and satisfactory agreement is noted.

  20. A modified Ozer-Taha type cosmological model

    Science.gov (United States)

    John, Moncy V.; Joseph, K. Babu

    1996-02-01

    A modified version of the Ozer and Taha nonsingular cosmological model is presented on the assumption that the universe's radius is complex if it is regarded as empty, but it contains matter when the radius is real. It also predicts the values: ΩM --- ρM/(ρC) ≈ 4/(3), ΩV --- ρV/(ρC) ≈ 2/(3) and Ω- --- ρ-/(ρC) ≪ 1 in the present nonrelativistic era, where ρM = matter density, ρV = vacuum energy density, ρ- = negative energy density and ρC = critical density.

  1. Underwater striling engine design with modified one-dimensional model

    Directory of Open Access Journals (Sweden)

    Daijin Li

    2015-05-01

    Full Text Available Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA. The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.

  2. Using a modified technology acceptance model in hospitals.

    Science.gov (United States)

    Aggelidis, Vassilios P; Chatzoglou, Prodromos D

    2009-02-01

    The use of information technology in the health care sector and especially in hospitals offers great potential for improving the quality of services provided and the efficiency and effectiveness of the personnel, but also for reducing the organizational expenses. However, the main question that arises according to the literature is whether hospital personnel are willing to use state of the art information technology while performing their tasks. This study attempts to address this issue by developing and testing a modified technology acceptance model taking into consideration other relevant models found in the literature. The original TAM has been extended to include some exogenous variables in order to examine HIS acceptance by Greek hospital personnel. Correlation, explanatory and confirmation factor analysis was performed to test the reliability and validity of the measurement model. The structural equation modeling technique has also been used to evaluate the causal model. The results indicate that perceived usefulness, ease of use, social influence, attitude, facilitating conditions and self-efficacy significantly affect hospital personnel behavioral intention. Training has a strong indirect impact on behavioral intention through the mediators of facilitating condition and ease of use. Furthermore, the existence of significant positive effects between self-efficacy and social influence, perceived usefulness and anxiety, and facilitating conditions and social influence is also supported. The proposed model can explain 87% of the variance of behavioral intention indicating that the core constructs of the technology acceptance models have a strong and statistically significant influence on hospital personnel usage intention.

  3. Composite modified Luneburg model of human eye lens.

    Science.gov (United States)

    Gómez-Correa, J E; Balderas-Mata, S E; Pierscionek, B K; Chávez-Cerda, S

    2015-09-01

    A new lens model based on the gradient-index Luneburg lens and composed of two oblate half spheroids of different curvatures is presented. The spherically symmetric Luneburg lens is modified to create continuous isoindicial contours and to incorporate curvatures that are similar to those found in a human lens. The imaging capabilities of the model and the changes in the gradient index profile are tested for five object distances, for a fixed geometry and for a fixed image distance. The central refractive index decreases with decreasing object distance. This indicates that in order to focus at the same image distance as is required in the eye, a decrease in refractive power is needed for rays from closer objects that meet the lens surface at steeper angles compared to rays from more distant objects. This ensures a highly focused image with no spherical aberration.

  4. Thermodynamical Aspects of Modified Holographic Dark Energy Model

    International Nuclear Information System (INIS)

    Li Hui; Zhang Yi

    2014-01-01

    We investigate the unified first law and the generalized second law in a modified holographic dark energy model. The thermodynamical analysis on the apparent horizon can work and the corresponding entropy formula is extracted from the systematic algorithm. The entropy correction term depends on the extra-dimension number of the brane as expected, but the interplay between the correction term and the extra dimensions is more complicated. With the unified first law of thermodynamics well-founded, the generalized second law of thermodynamics is discussed and it is found that the second law can be violated in certain circumstances. Particularly, if the number of the extra dimensions is larger than one, the generalized law of thermodynamics is always satisfied; otherwise, the validity of the second law can only be guaranteed with the Hubble radius greatly smaller than the crossover scale r c of the 5-dimensional DGP model. (geophysics, astronomy, and astrophysics)

  5. A modified social force model for crowd dynamics

    Science.gov (United States)

    Hassan, Ummi Nurmasyitah; Zainuddin, Zarita; Abu-Sulyman, Ibtesam M.

    2017-08-01

    The Social Force Model (SFM) is one of the most successful models in microscopic pedestrian studies that is used to study the movement of pedestrians. Many modifications have been done to improvise the SFM by earlier researchers such as the incorporation of a constant respect factor into the self-stopping mechanism. Before the new mechanism is introduced, the researchers found out that a pedestrian will immediately come to a halt if other pedestrians are near to him, which seems to be an unrealistic behavior. Therefore, researchers introduce a self-slowing mechanism to gradually stop a pedestrian when he is approaching other pedestrians. Subsequently, the dynamic respect factor is introduced into the self-slowing mechanism based on the density of the pedestrians to make the model even more realistic. In real life situations, the respect factor of the pedestrians should be dynamic values instead of a constant value. However, when we reproduce the simulation of the dynamic respect factor, we found that the movement of the pedestrians are unrealistic because the pedestrians are lacking perception of the pedestrians in front of him. In this paper, we adopted both dynamic respect factor and dynamic angular parameter, called modified dynamic respect factor, which is dependent on the density of the pedestrians. Simulations are performed in a normal unidirectional walkway to compare the simulated pedestrians' movements produced by both models. The results obtained showed that the modified dynamic respect factor produces more realistic movement of the pedestrians which conform to the real situation. Moreover, we also found that the simulations endow the pedestrian with a self-slowing mechanism and a perception of other pedestrians in front of him.

  6. Osseointegration of biochemically modified implants in an osteoporosis rodent model

    Directory of Open Access Journals (Sweden)

    B Stadlinger

    2013-07-01

    Full Text Available The present study examined the impact of implant surface modifications on osseointegration in an osteoporotic rodent model. Sandblasted, acid-etched titanium implants were either used directly (control or were further modified by surface conditioning with NaOH or by coating with one of the following active agents: collagen/chondroitin sulphate, simvastatin, or zoledronic acid. Control and modified implants were inserted into the proximal tibia of aged ovariectomised (OVX osteoporotic rats (n = 32/group. In addition, aged oestrogen competent animals received either control or NaOH conditioned implants. Animals were sacrificed 2 and 4 weeks post-implantation. The excised tibiae were utilised for biomechanical and morphometric readouts (n = 8/group/readout. Biomechanical testing revealed at both time points dramatically reduced osseointegration in the tibia of oestrogen deprived osteoporotic animals compared to intact controls irrespective of NaOH exposure. Consistently, histomorphometric and microCT analyses demonstrated diminished bone-implant contact (BIC, peri-implant bone area (BA, bone volume/tissue volume (BV/TV and bone-mineral density (BMD in OVX animals. Surface coating with collagen/chondroitin sulphate had no detectable impact on osseointegration. Interestingly, statin coating resulted in a transient increase in BIC 2 weeks post-implantation; which, however, did not correspond to improvement of biomechanical readouts. Local exposure to zoledronic acid increased BIC, BA, BV/TV and BMD at 4 weeks. Yet this translated only into a non-significant improvement of biomechanical properties. In conclusion, this study presents a rodent model mimicking severely osteoporotic bone. Contrary to the other bioactive agents, locally released zoledronic acid had a positive impact on osseointegration albeit to a lesser extent than reported in less challenging models.

  7. A modified symplectic PRK scheme for seismic wave modeling

    Science.gov (United States)

    Liu, Shaolin; Yang, Dinghui; Ma, Jian

    2017-02-01

    A new scheme for the temporal discretization of the seismic wave equation is constructed based on symplectic geometric theory and a modified strategy. The ordinary differential equation in terms of time, which is obtained after spatial discretization via the spectral-element method, is transformed into a Hamiltonian system. A symplectic partitioned Runge-Kutta (PRK) scheme is used to solve the Hamiltonian system. A term related to the multiplication of the spatial discretization operator with the seismic wave velocity vector is added into the symplectic PRK scheme to create a modified symplectic PRK scheme. The symplectic coefficients of the new scheme are determined via Taylor series expansion. The positive coefficients of the scheme indicate that its long-term computational capability is more powerful than that of conventional symplectic schemes. An exhaustive theoretical analysis reveals that the new scheme is highly stable and has low numerical dispersion. The results of three numerical experiments demonstrate the high efficiency of this method for seismic wave modeling.

  8. A marked correlation function for constraining modified gravity models

    Science.gov (United States)

    White, Martin

    2016-11-01

    Future large scale structure surveys will provide increasingly tight constraints on our cosmological model. These surveys will report results on the distance scale and growth rate of perturbations through measurements of Baryon Acoustic Oscillations and Redshift-Space Distortions. It is interesting to ask: what further analyses should become routine, so as to test as-yet-unknown models of cosmic acceleration? Models which aim to explain the accelerated expansion rate of the Universe by modifications to General Relativity often invoke screening mechanisms which can imprint a non-standard density dependence on their predictions. This suggests density-dependent clustering as a `generic' constraint. This paper argues that a density-marked correlation function provides a density-dependent statistic which is easy to compute and report and requires minimal additional infrastructure beyond what is routinely available to such survey analyses. We give one realization of this idea and study it using low order perturbation theory. We encourage groups developing modified gravity theories to see whether such statistics provide discriminatory power for their models.

  9. Global vegetation change predicted by the modified Budyko model

    Energy Technology Data Exchange (ETDEWEB)

    Monserud, R.A.; Tchebakova, N.M.; Leemans, R. (US Department of Agriculture, Moscow, ID (United States). Intermountain Research Station, Forest Service)

    1993-09-01

    A modified Budyko global vegetation model is used to predict changes in global vegetation patterns resulting from climate change (CO[sub 2] doubling). Vegetation patterns are predicted using a model based on a dryness index and potential evaporation determined by solving radiation balance equations. Climate change scenarios are derived from predictions from four General Circulation Models (GCM's) of the atmosphere (GFDL, GISS, OSU, and UKMO). All four GCM scenarios show similar trends in vegetation shifts and in areas that remain stable, although the UKMO scenario predicts greater warming than the others. Climate change maps produced by all four GCM scenarios show good agreement with the current climate vegetation map for the globe as a whole, although over half of the vegetation classes show only poor to fair agreement. The most stable areas are Desert and Ice/Polar Desert. Because most of the predicted warming is concentrated in the Boreal and Temperate zones, vegetation there is predicted to undergo the greatest change. Most vegetation classes in the Subtropics and Tropics are predicted to expand. Any shift in the Tropics favouring either Forest over Savanna, or vice versa, will be determined by the magnitude of the increased precipitation accompanying global warming. Although the model predicts equilibrium conditions to which many plant species cannot adjust (through migration or microevolution) in the 50-100 y needed for CO[sub 2] doubling, it is not clear if projected global warming will result in drastic or benign vegetation change. 72 refs., 3 figs., 3 tabs.

  10. Modified network simulation model with token method of bus access

    Directory of Open Access Journals (Sweden)

    L.V. Stribulevich

    2013-08-01

    Full Text Available Purpose. To study the characteristics of the local network with the marker method of access to the bus its modified simulation model was developed. Methodology. Defining characteristics of the network is carried out on the developed simulation model, which is based on the state diagram-layer network station with the mechanism of processing priorities, both in steady state and in the performance of control procedures: the initiation of a logical ring, the entrance and exit of the station network with a logical ring. Findings. A simulation model, on the basis of which can be obtained the dependencies of the application the maximum waiting time in the queue for different classes of access, and the reaction time usable bandwidth on the data rate, the number of network stations, the generation rate applications, the number of frames transmitted per token holding time, frame length was developed. Originality. The technique of network simulation reflecting its work in the steady condition and during the control procedures, the mechanism of priority ranking and handling was proposed. Practical value. Defining network characteristics in the real-time systems on railway transport based on the developed simulation model.

  11. A marked correlation function for constraining modified gravity models

    Energy Technology Data Exchange (ETDEWEB)

    White, Martin, E-mail: mwhite@berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States)

    2016-11-01

    Future large scale structure surveys will provide increasingly tight constraints on our cosmological model. These surveys will report results on the distance scale and growth rate of perturbations through measurements of Baryon Acoustic Oscillations and Redshift-Space Distortions. It is interesting to ask: what further analyses should become routine, so as to test as-yet-unknown models of cosmic acceleration? Models which aim to explain the accelerated expansion rate of the Universe by modifications to General Relativity often invoke screening mechanisms which can imprint a non-standard density dependence on their predictions. This suggests density-dependent clustering as a 'generic' constraint. This paper argues that a density-marked correlation function provides a density-dependent statistic which is easy to compute and report and requires minimal additional infrastructure beyond what is routinely available to such survey analyses. We give one realization of this idea and study it using low order perturbation theory. We encourage groups developing modified gravity theories to see whether such statistics provide discriminatory power for their models.

  12. Detailed analysis of the scope of the modified Firsov model

    International Nuclear Information System (INIS)

    Cruz, S.A.; Vargas-Aburto, C.; Brice, D.K.; Alonso, E.V.; Armour, D.G.

    1983-01-01

    A detailed and systematic analysis of the scope of the Firsov model as modified by Cheshire when no adjustable parameters are included in the calculations of the low-velocity electronic-stopping cross section is presented. For this purpose we summarize and extend our previously reported [Radiat. Eff. Lett. 43, 79 (1979); Nucl. Instrum. Methods 170, 205 (1980)] preliminary results on the role of all computational degrees of freedom that influence the outcome of the calculations, namely, (a) inclusion of trajectory, (b) accuracy of wave functions and speed of atomic electrons, (c) motion of Firsov's plane, and (d) consideration of experimental conditions. We find that the Firsov theory is accurate only within a factor of 2; therefore, at least a scale factor is necessary in order to get reasonable agreement with experiment

  13. Electron correlations in narrow energy bands: modified polar model approach

    Directory of Open Access Journals (Sweden)

    L. Didukh

    2008-09-01

    Full Text Available The electron correlations in narrow energy bands are examined within the framework of the modified form of polar model. This model permits to analyze the effect of strong Coulomb correlation, inter-atomic exchange and correlated hopping of electrons and explain some peculiarities of the properties of narrow-band materials, namely the metal-insulator transition with an increase of temperature, nonlinear concentration dependence of Curie temperature and peculiarities of transport properties of electronic subsystem. Using a variant of generalized Hartree-Fock approximation, the single-electron Green's function and quasi-particle energy spectrum of the model are calculated. Metal-insulator transition with the change of temperature is investigated in a system with correlated hopping. Processes of ferromagnetic ordering stabilization in the system with various forms of electronic DOS are studied. The static conductivity and effective spin-dependent masses of current carriers are calculated as a function of electron concentration at various DOS forms. The correlated hopping is shown to cause the electron-hole asymmetry of transport and ferromagnetic properties of narrow band materials.

  14. Modified quark-meson coupling model for nuclear matter

    International Nuclear Information System (INIS)

    Jin, X.; Jennings, B.K.

    1996-01-01

    The quark-meson coupling model for nuclear matter, which describes nuclear matter as nonoverlapping MIT bags bound by the self-consistent exchange of scalar and vector mesons, is modified by introducing medium modification of the bag constant. We model the density dependence of the bag constant in two different ways: One invokes a direct coupling of the bag constant to the scalar meson field, and the other relates the bag constant to the in-medium nucleon mass. Both models feature a decreasing bag constant with increasing density. We find that when the bag constant is significantly reduced in nuclear medium with respect to its free-space value, large canceling isoscalar Lorentz scalar and vector potentials for the nucleon in nuclear matter emerge naturally. Such potentials are comparable to those suggested by relativistic nuclear phenomenology and finite-density QCD sum rules. This suggests that the reduction of bag constant in nuclear medium may play an important role in low- and medium-energy nuclear physics. copyright 1996 The American Physical Society

  15. Ductile shear failure or plug failure of spot welds modelled by modified Gurson model

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Tvergaard, Viggo

    2010-01-01

    For resistance spot welded shear-lab specimens, interfacial failure under ductile shearing or ductile plug failure are analyzed numerically, using a shear modified Gurson model. The interfacial shear failure occurs under very low stress triaxiality, where the original Gurson model would predict...

  16. Modeling flow for modified concentric cylinder rheometer geometry

    Science.gov (United States)

    Ekeruche, Karen; Connelly, Kelly; Kavehpour, H. Pirouz

    2016-11-01

    Rheology experiments on biological fluids can be difficult when samples are limited in volume, sensitive to degradation, and delicate to extract from tissues. A probe-like geometry has been developed to perform shear creep experiments on biological fluids and to use the creep response to characterize fluid material properties. This probe geometry is a modified concentric cylinder setup, where the gap is large and we assume the inner cylinder rotates in an infinite fluid. To validate this assumption we perform shear creep tests with the designed probe on Newtonian and non-Newtonian fluids and vary the outer cylinder container diameter. We have also created a numerical model based on the probe geometry setup to compare with experimental results at different outer cylinder diameters. A creep test is modeled by applying rotation to the inner cylinder and solving for the deformation of the fluid throughout the gap. Steady state viscosity values are calculated from creep compliance curves and compared between experimental and numerical results.

  17. Modified uterine allotransplantation and immunosuppression procedure in the sheep model.

    Directory of Open Access Journals (Sweden)

    Li Wei

    Full Text Available OBJECTIVE: To develop an orthotopic, allogeneic, uterine transplantation technique and an effective immunosuppressive protocol in the sheep model. METHODS: In this pilot study, 10 sexually mature ewes were subjected to laparotomy and total abdominal hysterectomy with oophorectomy to procure uterus allografts. The cold ischemic time was 60 min. End-to-end vascular anastomosis was performed using continuous, non-interlocking sutures. Complete tissue reperfusion was achieved in all animals within 30 s after the vascular re-anastomosis, without any evidence of arterial or venous thrombosis. The immunosuppressive protocol consisted of tacrolimus, mycophenolate mofetil and methylprednisolone tablets. Graft viability was assessed by transrectal ultrasonography and second-look laparotomy at 2 and 4 weeks, respectively. RESULTS: Viable uterine tissue and vascular patency were observed on transrectal ultrasonography and second-look laparotomy. Histological analysis of the graft tissue (performed in one ewe revealed normal tissue architecture with a very subtle inflammatory reaction but no edema or stasis. CONCLUSION: We have developed a modified procedure that allowed us to successfully perform orthotopic, allogeneic, uterine transplantation in sheep, whose uterine and vascular anatomy (apart from the bicornuate uterus is similar to the human anatomy, making the ovine model excellent for human uterine transplant research.

  18. Constraints on modified gravity models from white dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Srimanta; Singh, Tejinder P. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005, Maharashtra (India); Shankar, Swapnil, E-mail: srimanta.banerjee@tifr.res.in, E-mail: swapnil.shankar@cbs.ac.in, E-mail: tpsingh@tifr.res.in [Department of Physics, Centre for Excellence in Basic Sciences, Mumbai 400098, Maharashtra (India)

    2017-10-01

    Modified gravity theories can introduce modifications to the Poisson equation in the Newtonian limit. As a result, we expect to see interesting features of these modifications inside stellar objects. White dwarf stars are one of the most well studied stars in stellar astrophysics. We explore the effect of modified gravity theories inside white dwarfs. We derive the modified stellar structure equations and solve them to study the mass-radius relationships for various modified gravity theories. We also constrain the parameter space of these theories from observations.

  19. Pattern formation through spatial interactions in a modified Daisyworld model

    Science.gov (United States)

    Alberti, Tommaso; Primavera, Leonardo; Lepreti, Fabio; Vecchio, Antonio; Carbone, Vincenzo

    2015-04-01

    The Daisyworld model is based on a hypothetical planet, like the Earth, which receives the radiant energy coming from a Sun-like star, and populated by two kinds of identical plants differing by their colour: white daisies reflecting light and black daisies absorbing light. The interactions and feedbacks between the collective biota of the planet and the incoming radiation form a self-regulating system where the conditions for life are maintained. We investigate a modified version of the Daisyworld model where a spatial dependency on latitude is introduced, and both a variable heat diffusivity along latitude and a simple greenhouse model are included. We show that the spatial interactions between the variables of the system can generate some equilibrium patterns which can locally stabilize the coexistence of the two vegetation types. The feedback on albedo is able to generate new equilibrium solutions which can efficiently self-regulate the planet climate, even for values of the solar luminosity relatively far from the current Earth conditions. The extension to spatial Daisyworld gives room to the possibility of inhomogeneous solar forcing in a curved planet, with explicit differences between poles and equator and the direct use of the heat diffusion equation. As a first approach, to describe a spherical planet, we consider the temperature T(θ,t) and the surface coverage as depending only on time and on latitude θ (-90° ≤ θ ≤ 90°). A second step is the introduction of the greenhouse effect in the model, the process by which outgoing infrared radiation is partly screened by greenhouse gases. This effect can be described by relaxing the black-body radiation hypothesis and by introducing a grayness function g(T) in the heat equation. As a third step, we consider a latitude dependence of the Earth's conductivity, χ = χ(θ). Considering these terms, using spherical coordinates and symmetry with respect to θ, the modified Daisyworld equations reduce to the

  20. A modified stratified model for the 3C 273 jet

    International Nuclear Information System (INIS)

    Liu Wenpo; Shen Zhiqiang

    2009-01-01

    We present a modified stratified jet model to interpret the observed spectral energy distributions of knots in the 3C 273 jet. Based on the hypothesis of the single index of the particle energy spectrum at injection and identical emission processes among all the knots, the observed difference of spectral shape among different 3C 273 knots can be understood as a manifestation of the deviation of the equivalent Doppler factor of stratified emission regions in an individual knot from a characteristic one. The summed spectral energy distributions of all ten knots in the 3C 273 jet can be well fitted by two components: a low-energy component (radio to optical) dominated by synchrotron radiation and a high-energy component (UV, X-ray and γ-ray) dominated by inverse Compton scattering of the cosmic microwave background. This gives a consistent spectral index of α = 0.88 (S v ∝ v -α ) and a characteristic Doppler factor of 7.4. Assuming the average of the summed spectrum as the characteristic spectrum of each knot in the 3C 273 jet, we further get a distribution of Doppler factors. We discuss the possible implications of these results for the physical properties in the 3C 273 jet. Future GeV observations with GLAST could separate the γ-ray emission of 3C 273 from the large scale jet and the small scale jet (i.e. the core) through measuring the GeV spectrum.

  1. Descriptive and discourse-referential modifiers in a layered model of the noun phrase

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2008-01-01

    This article argues that adnominal modifiers in a layered model of the noun phrase can be divided into two major subcategories: descriptive modifiers and discourse-referential modifiers. Whereas descriptive modifiers can be subdivided into classifying, qualifying, quantifying and localizing...... modifiers (section 2), discourse-referential modifiers in the noun phrase are concerned with the status of entities as referents in the world of discourse (section 3). I will pay particular attention to three issues: (i) formal reflections of the layered, semantic structure of the noun phrase (section 4...

  2. Modeling the Hydrologic Processes of a Permeable Pavement ...

    Science.gov (United States)

    A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has been developed in this study. The developed model can continuously simulate infiltration through the permeable pavement surface, exfiltration from the storage to the surrounding in situ soils, and clogging impacts on infiltration/exfiltration capacity at the pavement surface and the bottom of the subsurface storage unit. The exfiltration modeling component simulates vertical and horizontal exfiltration independently based on Darcy’s formula with the Green-Ampt approximation. The developed model can be arranged with physically-based modeling parameters, such as hydraulic conductivity, Manning’s friction flow parameters, saturated and field capacity volumetric water contents, porosity, density, etc. The developed model was calibrated using high-frequency observed data. The modeled water depths are well matched with the observed values (R2 = 0.90). The modeling results show that horizontal exfiltration through the side walls of the subsurface storage unit is a prevailing factor in determining the hydrologic performance of the system, especially where the storage unit is developed in a long, narrow shape; or with a high risk of bottom compaction and clogging. This paper presents unit

  3. Sediment Transport Model for a Surface Irrigation System

    Directory of Open Access Journals (Sweden)

    Damodhara R. Mailapalli

    2013-01-01

    Full Text Available Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in furrow irrigation. The irrigation hydraulic model simulates flow in a furrow irrigation system using the analytically solved zero-inertial overland flow equations and 1D-Green-Ampt, 2D-Fok, and Kostiakov-Lewis infiltration equations. Performance of the sediment transport model was evaluated for bare and cropped furrow fields. The results indicated that the sediment transport model can predict the initial sediment rate adequately, but the simulated sediment rate was less accurate for the later part of the irrigation event. Sensitivity analysis of the parameters of the sediment module showed that the soil erodibility coefficient was the most influential parameter for determining sediment load in furrow irrigation. The developed modeling tool can be used as a water management tool for mitigating sediment loss from the surface irrigated fields.

  4. Antitumor Properties of Modified Detonation Nanodiamonds and Sorbed Doxorubicin on the Model of Ehrlich Ascites Carcinoma.

    Science.gov (United States)

    Medvedeva, N N; Zhukov, E L; Inzhevatkin, E V; Bezzabotnov, V E

    2016-01-01

    We studied antitumor properties of modified detonation nanodiamonds loaded with doxorubicin on in vivo model of Ehrlich ascites carcinoma. The type of tumor development and morphological characteristics of the liver, kidneys, and spleen were evaluated in experimental animals. Modified nanodiamonds injected intraperitoneally produced no antitumor effect on Ehrlich carcinoma. However, doxorubicin did not lose antitumor activity after sorption on modified nanodiamonds.

  5. Modeling the probability distribution of peak discharge for infiltrating hillslopes

    Science.gov (United States)

    Baiamonte, Giorgio; Singh, Vijay P.

    2017-07-01

    Hillslope response plays a fundamental role in the prediction of peak discharge at the basin outlet. The peak discharge for the critical duration of rainfall and its probability distribution are needed for designing urban infrastructure facilities. This study derives the probability distribution, denoted as GABS model, by coupling three models: (1) the Green-Ampt model for computing infiltration, (2) the kinematic wave model for computing discharge hydrograph from the hillslope, and (3) the intensity-duration-frequency (IDF) model for computing design rainfall intensity. The Hortonian mechanism for runoff generation is employed for computing the surface runoff hydrograph. Since the antecedent soil moisture condition (ASMC) significantly affects the rate of infiltration, its effect on the probability distribution of peak discharge is investigated. Application to a watershed in Sicily, Italy, shows that with the increase of probability, the expected effect of ASMC to increase the maximum discharge diminishes. Only for low values of probability, the critical duration of rainfall is influenced by ASMC, whereas its effect on the peak discharge seems to be less for any probability. For a set of parameters, the derived probability distribution of peak discharge seems to be fitted by the gamma distribution well. Finally, an application to a small watershed, with the aim to test the possibility to arrange in advance the rational runoff coefficient tables to be used for the rational method, and a comparison between peak discharges obtained by the GABS model with those measured in an experimental flume for a loamy-sand soil were carried out.

  6. Comparative analysis of modified PMV models and SET models to predict human thermal sensation in naturally ventilated buildings

    DEFF Research Database (Denmark)

    Gao, Jie; Wang, Yi; Wargocki, Pawel

    2015-01-01

    In this paper, a comparative analysis was performed on the human thermal sensation estimated by modified predicted mean vote (PMV) models and modified standard effective temperature (SET) models in naturally ventilated buildings; the data were collected in field study. These prediction models were....../s, the expectancy factors for the extended PMV model and the extended SET model were from 0.770 to 0.974 and from 1.330 to 1.363, and the adaptive coefficients for the adaptive PMV model and the adaptive SET model were from 0.029 to 0.167 and from-0.213 to-0.195. In addition, the difference in thermal sensation...... between the measured and predicted values using the modified PMV models exceeded 25%, while the difference between the measured thermal sensation and the predicted thermal sensation using modified SET models was approximately less than 25%. It is concluded that the modified SET models can predict human...

  7. The modified turning bands (MTB) model for space-time rainfall. I. Model definition and properties

    Science.gov (United States)

    Mellor, Dale

    1996-02-01

    A new stochastic model of space-time rainfall, the Modified Turning Bands (MTB) model, is proposed which reproduces, in particular, the movements and developments of rainbands, cluster potential regions and raincells, as well as their respective interactions. The ensemble correlation structure is unsuitable for practical estimation of the model parameters because the model is not ergodic in this statistic, and hence it cannot easily be measured from a single real storm. Thus, some general theory on the internal covariance structure of a class of stochastic models is presented, of which the MTB model is an example. It is noted that, for the MTB model, the internal covariance structure may be measured from a single storm, and can thus be used for model identification.

  8. Estimating soil hydrological response by combining precipitation-runoff modeling and hydro-functional soil homogeneous units

    Science.gov (United States)

    Aroca-Jimenez, Estefania; Bodoque, Jose Maria; Diez-Herrero, Andres

    2015-04-01

    Flash floods constitute one of the natural hazards better able to generate risk, particularly with regard to Society. The complexity of this process and its dependence on various factors related to the characteristics of the basin and rainfall make flash floods are difficult to characterize in terms of their hydrological response.To do this, it is essential a proper analysis of the so called 'initial abstractions'. Among all of these processes, infiltration plays a crucial role in explaining the occurrence of floods in mountainous basins.For its characterization the Green-Ampt model , which depends on the characteristics of rainfall and physical properties of soil has been used in this work.This is a method enabling to simulate floods in mountainous basins where hydrological response is sub-daily. However, it has the disadvantage that it is based on physical properties of soil which have a high spatial variability. To address this difficulty soil mapping units have been delineated according to the geomorphological landforms and elements. They represent hydro-functional mapping units that are theoretically homogeneous from the perspective of the pedostructure parameters of the pedon. So the soil texture of each homogeneous group of landform units was studied by granulometric analyses using standarized sieves and Sedigraph devices. In addition, uncertainty associated with the parameterization of the Green-Ampt method has been estimated by implementing a Monte Carlo approach, which required assignment of the proper distribution function to each parameter.The suitability of this method was contrasted by calibrating and validating a hydrological model, in which the generation of runoff hydrograph has been simulated using the SCS unit hydrograph (HEC-GeoHMS software), while flood wave routing has been characterized using the Muskingum-Cunge method. Calibration and validation of the model was from the use of an automatic routine based on the employ of the search algorithm

  9. Bivariate Kumaraswamy Models via Modified FGM Copulas: Properties and Applications

    Directory of Open Access Journals (Sweden)

    Indranil Ghosh

    2017-11-01

    Full Text Available A copula is a useful tool for constructing bivariate and/or multivariate distributions. In this article, we consider a new modified class of FGM (Farlie–Gumbel–Morgenstern bivariate copula for constructing several different bivariate Kumaraswamy type copulas and discuss their structural properties, including dependence structures. It is established that construction of bivariate distributions by this method allows for greater flexibility in the values of Spearman’s correlation coefficient, ρ and Kendall’s τ .

  10. Study of melting of molecular crystals by a modified Pople-Karasz model

    Science.gov (United States)

    Yazıcı, Mustafa; Özgan, Şükrü; Keskin, Mustafa

    2005-02-01

    A new modified model that combines the modified models of Chandrasekhar et al. with those of Keskin and Özgan, which are based on the Pople-Karasz theory, is applied to study the thermodynamics of melting and solid-solid transitions of molecular crystals. The thermodynamic properties of the disordered system are evaluated relative to those of the perfectly ordered one using the lowest approximation of the cluster-variation method, which is identical to the mean-field approximation. A good agreement is found between the present modified theory and the available experimental data. For melting transitions the agreement is excellent and much better than with the calculations of the Pople-Karasz theory and its previous modified theories. Approximate agreement is obtained for the solid-solid transitions. However, for these transition the experimental agreement with the present modified theory is still better than previous modified theories except at zero and low pressures.

  11. A review of animal models used to evaluate potential allergenicity of genetically modified organisms (GMOs)

    DEFF Research Database (Denmark)

    Marsteller, Nathan; Bøgh, Katrine Lindholm; Goodman, Richard E.

    2017-01-01

    Food safety regulators request prediction of allergenicity for newly expressed proteins in genetically modified (GM) crops and in novel foods. Some have suggested using animal models to assess potential allergenicity. A variety of animal models have been used in research to evaluate sensitisation...... of genetically modified organisms (GMOs).......Food safety regulators request prediction of allergenicity for newly expressed proteins in genetically modified (GM) crops and in novel foods. Some have suggested using animal models to assess potential allergenicity. A variety of animal models have been used in research to evaluate sensitisation...

  12. Modelling pesticides volatilisation in greenhouses: Sensitivity analysis of a modified PEARL model.

    Science.gov (United States)

    Houbraken, Michael; Doan Ngoc, Kim; van den Berg, Frederik; Spanoghe, Pieter

    2017-12-01

    The application of the existing PEARL model was extended to include estimations of the concentration of crop protection products in greenhouse (indoor) air due to volatilisation from the plant surface. The model was modified to include the processes of ventilation of the greenhouse air to the outside atmosphere and transformation in the air. A sensitivity analysis of the model was performed by varying selected input parameters on a one-by-one basis and comparing the model outputs with the outputs of the reference scenarios. The sensitivity analysis indicates that - in addition to vapour pressure - the model had the highest ratio of variation for the rate ventilation rate and thickness of the boundary layer on the day of application. On the days after application, competing processes, degradation and uptake in the plant, becomes more important. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Modelling Eutectic Growth in Unmodified and Modified Near-Eutectic Al-Si Alloy

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat; Hattel, Jesper Henri; Taylor, John A.

    2013-01-01

    growth parameters from the literature that depend on the type of modification (unmodified, Na-modified or Sr-modified) are used to describe differences in growth of the alloys. Modelling results are compared with solidification experiments where an Al-12.5wt%Si alloy was cast in unmodified, Na modified......A numerical model that describes solidification of primary aluminium grains and nucleation and growth of eutectic cells is used to analyse the solidification of an Al-12.5wt% Si alloy. Nucleation of eutectic cells is modelled using an Oldfield-type nucleation model where the number of nuclei...... and Sr modified forms. The model confirms experimental observations of how modification and alloy composition influence nucleation, growth and finally the size of eutectic cells in the alloys. Modelling results are used to explain how cooling conditions in the casting act together with the nuclei density...

  14. A modified wake oscillator model for predicting vortex induced vibration of heat exchanger tube

    International Nuclear Information System (INIS)

    Feng Zhipeng; Zang Fenggang; Zhang Yixiong; Ye Xianhui

    2014-01-01

    Base on the classical wake oscillator model, a new modified wake oscillator model is proposed, for predicting vortex induced vibration of heat exchanger tube in uniform current. The comparison between the new wake oscillator model and experimental show that the present model can simulate the characteristics of vortex induced vibration of tube. Firstly, the research shows that the coupled fluid-structure dynamical system should be modeled by combined displacement and acceleration mode. Secondly, the empirical parameter in wake oscillator model depends on the material properties of the structure, instead of being a universal constant. Lastly, the results are compared between modified wake oscillator model and fluid-structure interaction numerical model. It shows the present, predicted results are compared to the fluid-structure interaction numerical data. The new modified wake oscillator model can predict the vortex induced heat exchanger tube vibration feasibly. (authors)

  15. Results on a Binding Neuron Model and Their Implications for Modified Hourglass Model for Neuronal Network

    Directory of Open Access Journals (Sweden)

    Viswanathan Arunachalam

    2013-01-01

    Full Text Available The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008 in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.

  16. Optimization of spectral printer modeling based on a modified cellular Yule-Nielsen spectral Neugebauer model.

    Science.gov (United States)

    Liu, Qiang; Wan, Xiaoxia; Xie, Dehong

    2014-06-01

    The study presented here optimizes several steps in the spectral printer modeling workflow based on a cellular Yule-Nielsen spectral Neugebauer (CYNSN) model. First, a printer subdividing method was developed that reduces the number of sub-models while maintaining the maximum device gamut. Second, the forward spectral prediction accuracy of the CYNSN model for each subspace of the printer was improved using back propagation artificial neural network (BPANN) estimated n values. Third, a sequential gamut judging method, which clearly reduced the complexity of the optimal sub-model and cell searching process during printer backward modeling, was proposed. After that, we further modified the use of the modeling color metric and comprehensively improved the spectral and perceptual accuracy of the spectral printer model. The experimental results show that the proposed optimization approaches provide obvious improvements in aspects of the modeling accuracy or efficiency for each of the corresponding steps, and an overall improvement of the optimized spectral printer modeling workflow was also demonstrated.

  17. Modelo hidrológico para estimativa do escoamento superficial em áreas agrícolas A hydrologic model to estimate the surface runoff in agricultural lands

    Directory of Open Access Journals (Sweden)

    Fernando F. Pruski

    2001-05-01

    Full Text Available Desenvolveu-se um modelo hidrológico para estimar o escoamento superficial em áreas sob condições agrícolas. O modelo é baseado na análise dos diversos processos associados ao balanço hídrico e nele se usa a equação de intensidade, duração e freqüência da precipitação para estimar a intensidade de precipitação e a equação de Green-Ampt modificada por Mein-Larson, para estimar a velocidade de infiltração permitindo, também, a consideração da interceptação pela cobertura vegetal e do armazenamento de água sobre a superfície do solo por meio de diferentes metodologias. O escoamento superficial começa após a capacidade de armazenamento sobre a superfície do solo ter sido preenchida, e é calculado subtraindo-se a velocidade de infiltração da água no solo da intensidade de precipitação durante o intervalo de tempo em que a intensidade da chuva é maior que a velocidade de infiltração. Resultados de um experimento de validação do modelo e duas aplicações práticas são apresentados, sendo que os resultados obtidos com o modelo foram muito próximos daqueles observados no campo.A hydrologic model was developed to estimate the surface runoff under agricultural conditions. The model is process-based and uses the intensity-duration-frequency equation to calculate the rainfall intensity and the Green-Ampt-Mein-Larson equation to estimate the infiltration rate. The runoff begins after the maximum surface storage on the soil surface has been reached. It is calculated by subtracting the infiltration rate from the rainfall intensity during the interval of time that the rainfall intensity is greater than the infiltration rate. The model also allows the calculation of the deep percolation and the actual soil-water content. Results from a validation experiment and two practical applications of the model are also presented. The results obtained with the model were approximately the same as those observed in the field.

  18. Disease-threat model explains acceptance of genetically modified products

    Directory of Open Access Journals (Sweden)

    Prokop Pavol

    2013-01-01

    Full Text Available Natural selection favoured survival of individuals who were able to avoid disease. The behavioural immune system is activated especially when our sensory system comes into contact with disease-connoting cues and/or when these cues resemble disease threat. We investigated whether or not perception of modern risky technologies, risky behaviour, expected reproductive goals and food neophobia are associated with the behavioural immune system related to specific attitudes toward genetically modified (GM products. We found that respondents who felt themselves more vulnerable to infectious diseases had significantly more negative attitudes toward GM products. Females had less positive attitudes toward GM products, but engaging in risky behaviours, the expected reproductive goals of females and food neophobia did not predict attitudes toward GM products. Our results suggest that evolved psychological mechanisms primarily designed to protect us against pathogen threat are activated by modern technologies possessing potential health risks.

  19. A modified Rietveld method to model highly anisotropic ceramics

    International Nuclear Information System (INIS)

    Tutuncu, G.; Motahari, M.; Daymond, M.R.; Ustundag, E.

    2012-01-01

    High energy X-ray diffraction was employed to probe the complex constitutive behavior of a polycrystalline ferroelectric material in various sample orientations. Pb(Zn,Nb)O 3 –Pb(Zr,Ti)O 3 (PZN–PZT) ceramics were subjected to a cyclic bipolar electric field while diffraction patterns were taken. Using transmission geometry and a two-dimensional detector, lattice strain and texture evolution (domain switching) were measured in multiple sample directions simultaneously. In addition, texture analysis suggests that non-180° domain switching is coupled with lattice strain evolution during uniaxial electrical loading. As a result of this material’s high strain anisotropy, the full-pattern Rietveld method was inadequate to analyze the diffraction data. Instead, a modified Rietveld method, which includes an elastic anisotropy term, yielded significant improvements in the data analysis results.

  20. The modified Black-Scholes model via constant elasticity of variance for stock options valuation

    Science.gov (United States)

    Edeki, S. O.; Owoloko, E. A.; Ugbebor, O. O.

    2016-02-01

    In this paper, the classical Black-Scholes option pricing model is visited. We present a modified version of the Black-Scholes model via the application of the constant elasticity of variance model (CEVM); in this case, the volatility of the stock price is shown to be a non-constant function unlike the assumption of the classical Black-Scholes model.

  1. Modified allocation capacitated planning model in blood supply chain management

    Science.gov (United States)

    Mansur, A.; Vanany, I.; Arvitrida, N. I.

    2018-04-01

    Blood supply chain management (BSCM) is a complex process management that involves many cooperating stakeholders. BSCM involves four echelon processes, which are blood collection or procurement, production, inventory, and distribution. This research develops an optimization model of blood distribution planning. The efficiency of decentralization and centralization policies in a blood distribution chain are compared, by optimizing the amount of blood delivered from a blood center to a blood bank. This model is developed based on allocation problem of capacitated planning model. At the first stage, the capacity and the cost of transportation are considered to create an initial capacitated planning model. Then, the inventory holding and shortage costs are added to the model. These additional parameters of inventory costs lead the model to be more realistic and accurate.

  2. Complex Price Dynamics in the Modified Kaldorian Model

    Czech Academy of Sciences Publication Activity Database

    Kodera, Jan; Van Tran, Q.; Vošvrda, Miloslav

    2013-01-01

    Roč. 22, č. 3 (2013), s. 358-384 ISSN 1210-0455 R&D Projects: GA ČR(CZ) GBP402/12/G097 Institutional support: RVO:67985556 Keywords : Priice dynamics, * numerical examples * two-equation model * four-equation model * nonlinear time series analysis Subject RIV: AH - Economics Impact factor: 0.208, year: 2013 http://library.utia.cas.cz/separaty/2013/E/kodera-model of price dynamics and chaos.pdf

  3. a modified intervention model for gross domestic product variable

    African Journals Online (AJOL)

    observations on a variable that have been measured at ... assumption that successive values in the data file ... these interventions, one may try to evaluate the effect of ... generalized series by comparing the distinct periods. A ... the process of checking for adequacy of the model based .... As a result, the model's forecast will.

  4. A-Priori Tuning of Modified Magnussen Combustion Model

    Science.gov (United States)

    Norris, A. T.

    2016-01-01

    In the application of CFD to turbulent reacting flows, one of the main limitations to predictive accuracy is the chemistry model. Using a full or skeletal kinetics model may provide good predictive ability, however, at considerable computational cost. Adding the ability to account for the interaction between turbulence and chemistry improves the overall fidelity of a simulation but adds to this cost. An alternative is the use of simple models, such as the Magnussen model, which has negligible computational overhead, but lacks general predictive ability except for cases that can be tuned to the flow being solved. In this paper, a technique will be described that allows the tuning of the Magnussen model for an arbitrary fuel and flow geometry without the need to have experimental data for that particular case. The tuning is based on comparing the results of the Magnussen model and full finite-rate chemistry when applied to perfectly and partially stirred reactor simulations. In addition, a modification to the Magnussen model is proposed that allows the upper kinetic limit for the reaction rate to be set, giving better physical agreement with full kinetic mechanisms. This procedure allows a simple reacting model to be used in a predictive manner, and affords significant savings in computational costs for simulations.

  5. Multifractal regime transition in a modified minority game model

    International Nuclear Information System (INIS)

    Crepaldi, Antonio F.; Rodrigues Neto, Camilo; Ferreira, Fernando F.; Francisco, Gerson

    2009-01-01

    The search for more realistic modeling of financial time series reveals several stylized facts of real markets. In this work we focus on the multifractal properties found in price and index signals. Although the usual minority game (MG) models do not exhibit multifractality, we study here one of its variants that does. We show that the nonsynchronous MG models in the nonergodic phase is multifractal and in this sense, together with other stylized facts, constitute a better modeling tool. Using the structure function (SF) approach we detected the stationary and the scaling range of the time series generated by the MG model and, from the linear (non-linear) behavior of the SF we identified the fractal (multifractal) regimes. Finally, using the wavelet transform modulus maxima (WTMM) technique we obtained its multifractal spectrum width for different dynamical regimes.

  6. Hypersurface Homogeneous Cosmological Model in Modified Theory of Gravitation

    Science.gov (United States)

    Katore, S. D.; Hatkar, S. P.; Baxi, R. J.

    2016-12-01

    We study a hypersurface homogeneous space-time in the framework of the f (R, T) theory of gravitation in the presence of a perfect fluid. Exact solutions of field equations are obtained for exponential and power law volumetric expansions. We also solve the field equations by assuming the proportionality relation between the shear scalar (σ ) and the expansion scalar (θ ). It is observed that in the exponential model, the universe approaches isotropy at large time (late universe). The investigated model is notably accelerating and expanding. The physical and geometrical properties of the investigated model are also discussed.

  7. Indeterminacy and stability in a modified Romer model

    Czech Academy of Sciences Publication Activity Database

    Slobodyan, Sergey

    2007-01-01

    Roč. 29, č. 1 (2007), s. 169-177 ISSN 0164-0704 Institutional research plan: CEZ:MSM0021620846 Keywords : indeterminacy * Hopf bifurcation * Romer model Subject RIV: AH - Economics Impact factor: 0.360, year: 2007

  8. Application of GIS to modified models of vehicle emission dispersion

    Science.gov (United States)

    Jin, Taosheng; Fu, Lixin

    This paper reports on a preliminary study of the forecast and evaluation of transport-related air pollution dispersion in urban areas. Some modifications of the traditional Gauss dispersion models are provided, and especially a crossroad model is built, which considers the great variation of vehicle emission attributed to different driving patterns at the crossroad. The above models are combined with a self-developed geographic information system (GIS) platform, and a simulative system with graphical interfaces is built. The system aims at visually describing the influences on the urban environment by urban traffic characteristics and therefore gives a reference to the improvement of urban air quality. Due to the introduction of a self-developed GIS platform and a creative crossroad model, the system is more effective, flexible and accurate. Finally, a comparison of the simulated (predicted) and observed hourly concentration is given, which indicates a good simulation.

  9. Asymmetric nuclear matter in a modified quark meson coupling model

    International Nuclear Information System (INIS)

    Mishra, R.N.; Sahoo, H.S.; Panda, P.K.; Barik, N.

    2014-01-01

    In an earlier attempt we have successfully used this model in developing the nuclear equation of state and analysed various other bulk properties of symmetric nuclear matter with the dependence of quark masses. In the present work we want to apply the model to analyze asymmetric nuclear matter with the variation of the asymmetry parameter y p as well as analyze the effects of symmetry energy and the slope of the symmetry energy L

  10. Spherical collapse and cluster counts in modified gravity models

    International Nuclear Information System (INIS)

    Martino, Matthew C.; Stabenau, Hans F.; Sheth, Ravi K.

    2009-01-01

    Modifications to the gravitational potential affect the nonlinear gravitational evolution of large scale structures in the Universe. To illustrate some generic features of such changes, we study the evolution of spherically symmetric perturbations when the modification is of Yukawa type; this is nontrivial, because we should not and do not assume that Birkhoff's theorem applies. We then show how to estimate the abundance of virialized objects in such models. Comparison with numerical simulations shows reasonable agreement: When normalized to have the same fluctuations at early times, weaker large scale gravity produces fewer massive halos. However, the opposite can be true for models that are normalized to have the same linear theory power spectrum today, so the abundance of rich clusters potentially places interesting constraints on such models. Our analysis also indicates that the formation histories and abundances of sufficiently low mass objects are unchanged from standard gravity. This explains why simulations have found that the nonlinear power spectrum at large k is unaffected by such modifications to the gravitational potential. In addition, the most massive objects in models with normalized cosmic microwave background and weaker gravity are expected to be similar to the high-redshift progenitors of the most massive objects in models with stronger gravity. Thus, the difference between the cluster and field galaxy populations is expected to be larger in models with stronger large scale gravity.

  11. A modified elastic foundation contact model for application in 3D models of the prosthetic knee.

    Science.gov (United States)

    Pérez-González, Antonio; Fenollosa-Esteve, Carlos; Sancho-Bru, Joaquín L; Sánchez-Marín, Francisco T; Vergara, Margarita; Rodríguez-Cervantes, Pablo J

    2008-04-01

    Different models have been used in the literature for the simulation of surface contact in biomechanical knee models. However, there is a lack of systematic comparisons of these models applied to the simulation of a common case, which will provide relevant information about their accuracy and suitability for application in models of the implanted knee. In this work a comparison of the Hertz model (HM), the elastic foundation model (EFM) and the finite element model (FEM) for the simulation of the elastic contact in a 3D model of the prosthetic knee is presented. From the results of this comparison it is found that although the nature of the EFM offers advantages when compared with that of the HM for its application to realistic prosthetic surfaces, and when compared with the FEM in CPU time, its predictions can differ from FEM in some circumstances. These differences are considerable if the comparison is performed for prescribed displacements, although they are less important for prescribed loads. To solve these problems a new modified elastic foundation model (mEFM) is proposed that maintains basically the simplicity of the original model while producing much more accurate results. In this paper it is shown that this new mEFM calculates pressure distribution and contact area with accuracy and short computation times for toroidal contacting surfaces. Although further work is needed to confirm its validity for more complex geometries the mEFM is envisaged as a good option for application in 3D knee models to predict prosthetic knee performance.

  12. Property Analysis of Exfoliated Graphite Nanoplatelets Modified Asphalt Model Using Molecular Dynamics (MD Method

    Directory of Open Access Journals (Sweden)

    Hui Yao

    2017-01-01

    Full Text Available This Molecular Dynamics (MD simulation paper presents a physical property comparison study between exfoliated graphite nanoplatelets (xGNP modified and control asphalt models, including density, glass transition temperature, viscosity and thermal conductivity. The three-component control asphalt model consists of asphaltenes, aromatics, and saturates based on previous references. The xGNP asphalt model was built by incorporating an xGNP and control asphalt model and controlling mass ratios to represent the laboratory prepared samples. The Amber Cornell Extension Force Field (ACEFF was used with assigned molecular electro-static potential (ESP charge from NWChem analysis. After optimization and ensemble relaxation, the properties of the control and xGNP modified asphalt models were computed and analyzed using the MD method. The MD simulated results have a similar trend as the test results. The property analysis showed that: (1 the density of the xGNP modified model is higher than that of the control model; (2 the glass transition temperature of the xGNP modified model is closer to the laboratory data of the Strategic Highway Research Program (SHRP asphalt binders than that of the control model; (3 the viscosities of the xGNP modified model at different temperatures are higher than those of the control model, and it coincides with the trend in the laboratory data; (4 the thermal conductivities of the xGNP modified asphalt model are higher than those of the control asphalt model at different temperatures, and it is consistent with the trend in the laboratory data.

  13. Non-uniform overland flow-infiltration model for roadside swales

    Science.gov (United States)

    García-Serrana, María; Gulliver, John S.; Nieber, John L.

    2017-09-01

    There is a need to quantify the hydrologic performance of vegetated roadside swales (drainage ditches) as stormwater control measures (SCMs). To quantify their infiltration performance in both the side slope and the channel of the swale, a model has been developed for coupling a Green-Ampt-Mein-Larson (GAML) infiltration submodel with kinematic wave submodels for both overland flow down the side slope and open channel flow for flow in the ditch. The coupled GAML submodel and overland flow submodel has been validated using data collected in twelve simulated runoff tests in three different highways located in the Minneapolis-St. Paul metropolitan area, MN. The percentage of the total water infiltrated into the side slope is considerably greater than into the channel. Thus, the side slope of a roadside swale is the main component contributing to the loss of runoff by infiltration and the channel primarily conveys the water that runs off the side slope, for the typical design found in highways. Finally, as demonstrated in field observations and the model, the fraction of the runoff/rainfall infiltrated (Vi∗) into the roadside swale appears to increase with a dimensionless saturated hydraulic conductivity (Ks∗), which is a function of the saturated hydraulic conductivity, rainfall intensity, and dimensions of the swale and contributing road surface. For design purposes, the relationship between Vi∗ and Ks∗ can provide a rough estimate of the fraction of runoff/rainfall infiltrated with the few essential parameters that appear to dominate the results.

  14. The baryon-baryon interaction in a modified quark model

    International Nuclear Information System (INIS)

    Zhang Zongye; Faessler, Amand; Straub, U.; Glozman, L.Ya.

    1994-01-01

    The quark-cluster model with coupling constants constraint by chiral symmetry is extended to include strange quarks. In this model, besides the confinement and one-gluon exchange potentials, the pseudoscalar mesons and sigma (σ) meson exchanges are included as the nonperturbative effect. Using this interaction we studied the binding energy of the deuteron, the NN scattering phase shifts and the hyperon-nucleon cross sections in the framework of the resonating group method (RGM). The results are reasonably consistent with experiments. ((orig.))

  15. Modified bond model for shear in slabs under concentrated loads

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; De Boer, A.

    2015-01-01

    Slabs subjected to concentrated loads close to supports, as occurring for truck loads on slab bridges, are less studied than beams in shear or slab-column connections in punching. To predict the shear capacity for this case, the Bond Model for concentric punching shear was studied initially.

  16. Modified Normal Demand Distributions in (R,S)-Inventory Models

    NARCIS (Netherlands)

    Strijbosch, L.W.G.; Moors, J.J.A.

    2003-01-01

    To model demand, the normal distribution is by far the most popular; the disadvantage that it takes negative values is taken for granted.This paper proposes two modi.cations of the normal distribution, both taking non-negative values only.Safety factors and order-up-to-levels for the familiar (R,

  17. Modifying the pom-pom model for extensional viscosity overshoots

    DEFF Research Database (Denmark)

    Hawke, L. D. G.; Huang, Qian; Hassager, Ole

    2015-01-01

    We have developed a variant of the pom-pom model that qualitatively describes two surprising features recently observed in filament stretching rheometer experiments of uniaxial extensional flow of industrial branched polymer resins: (i) Overshoots of the transient stress during steady flow and (i...

  18. Accuracy improvement of the modified EDM model for non-premixed turbulent combustion in gas turbine

    Directory of Open Access Journals (Sweden)

    Qiong Li

    2015-09-01

    Full Text Available Eight bluff body and swirl turbulent diffusion flames resembling the flow field and combustion inside gas turbine combustors are simulated and the simulation results are compared with experimental data. It is revealed that the original modified EDM model could not predict the temperature profile accurately. A more accurate model is developed and validated for gas turbine combustion application. However, this model under predicts the flame temperature for the regular round jet flames indicating that no universal form of the modified EDM model could be achieved for the combustion simulation of both gas furnaces and gas turbines.

  19. Modified Dugdale crack models - some easy crack relations

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    the same strength as a plain Dugdale model. The critical energy release rates Gamma_CR, however, become different. Expressions (with easy computer algorithms) are presented in the paper which relate critical energy release rates and crack geometry to arbitrary cohesive stress distributions.For future...... lifetime analysis of viscoelastic materials strain energy release rates, crack geometries, and cohesive stress distributions are considered as related to sub-critical loads sigma stress-deformation tests......The Dugdale crack model is widely used in materials science to predict strength of defective (cracked) materials. A stable Dugdale crack in an elasto-plastic material is prevented from spreading by uniformly distributed cohesive stresses acting in narrow areas at the crack tips. These stresses...

  20. A multi-scale modeling of surface effect via the modified boundary Cauchy-Born model

    Energy Technology Data Exchange (ETDEWEB)

    Khoei, A.R., E-mail: arkhoei@sharif.edu; Aramoon, A.

    2012-10-01

    In this paper, a new multi-scale approach is presented based on the modified boundary Cauchy-Born (MBCB) technique to model the surface effects of nano-structures. The salient point of the MBCB model is the definition of radial quadrature used in the surface elements which is an indicator of material behavior. The characteristics of quadrature are derived by interpolating data from atoms laid in a circular support around the quadrature, in a least-square scene. The total-Lagrangian formulation is derived for the equivalent continua by employing the Cauchy-Born hypothesis for calculating the strain energy density function of the continua. The numerical results of the proposed method are compared with direct atomistic and finite element simulation results to indicate that the proposed technique provides promising results for modeling surface effects of nano-structures. - Highlights: Black-Right-Pointing-Pointer A multi-scale approach is presented to model the surface effects in nano-structures. Black-Right-Pointing-Pointer The total-Lagrangian formulation is derived by employing the Cauchy-Born hypothesis. Black-Right-Pointing-Pointer The radial quadrature is used to model the material behavior in surface elements. Black-Right-Pointing-Pointer The quadrature characteristics are derived using the data at the atomistic level.

  1. Modified multiblock partial least squares path modeling algorithm with backpropagation neural networks approach

    Science.gov (United States)

    Yuniarto, Budi; Kurniawan, Robert

    2017-03-01

    PLS Path Modeling (PLS-PM) is different from covariance based SEM, where PLS-PM use an approach based on variance or component, therefore, PLS-PM is also known as a component based SEM. Multiblock Partial Least Squares (MBPLS) is a method in PLS regression which can be used in PLS Path Modeling which known as Multiblock PLS Path Modeling (MBPLS-PM). This method uses an iterative procedure in its algorithm. This research aims to modify MBPLS-PM with Back Propagation Neural Network approach. The result is MBPLS-PM algorithm can be modified using the Back Propagation Neural Network approach to replace the iterative process in backward and forward step to get the matrix t and the matrix u in the algorithm. By modifying the MBPLS-PM algorithm using Back Propagation Neural Network approach, the model parameters obtained are relatively not significantly different compared to model parameters obtained by original MBPLS-PM algorithm.

  2. Simulating Landscape Sediment Transport Capacity by Using a Modified SWAT Model.

    Science.gov (United States)

    Bonumá, Nadia B; Rossi, Colleen G; Arnold, Jeffrey G; Reichert, José M; Minella, Jean P; Allen, Peter M; Volk, Martin

    2014-01-01

    Sediment delivery from hillslopes to rivers is spatially variable and may lead to long-term delays between initial erosion and related sediment yield at the watershed outlet. Consideration of spatial variability is important for developing sound strategies for water quality improvement and soil protection at the watershed scale. Hence, the Soil and Water Assessment Tool (SWAT) was modified and tested in this study to simulate the landscape transport capacity of sediment. The study area was the steeply sloped Arroio Lino watershed in southern Brazil. Observed sediment yield data at the watershed outlet were used to calibrate and validate a modified SWAT model. For the calibration period, the modified model performed better than the unaltered SWAT2009 version; the models achieved Nash-Sutcliffe efficiency (NSE) values of 0.7 and -0.1, respectively. Nash-Sutcliffe efficiencies were less for the validation period, but the modified model's NSE was higher than the unaltered model (-1.4 and -12.1, respectively). Despite the relatively low NSE values, the results of this first test are promising because the model modifications lowered the percent bias in sediment yield from 73 to 18%. Simulation results for the modified model indicated that approximately 60% of the mobilized soil is deposited along the landscape before it reaches the river channels. This research demonstrates the modified model's ability to simulate sediment yield in watersheds with steep slopes. The results suggest that integration of the sediment deposition routine in SWAT increases accuracy in steeper areas while significantly improving its ability to predict the spatial distribution of sediment deposition areas. Further work is needed regarding (i) improved strategies for spatially distributed sediment transport measurements (for improving process knowledge and model evaluation) and (ii) extensive model tests in other well instrumented experimental watersheds with differing topographic configurations

  3. Enterprise Architecture Modeling of Core Administrative Systems at KTH : A Modifiability Analysis

    OpenAIRE

    Rosell, Peter

    2012-01-01

    This project presents a case study of modifiability analysis on the Information Systems which are central to the core business processes of Royal Institution of Technology in Stockholm, Sweden by creating, updating and using models. The case study was limited to modifiability regarding only specified Information Systems. The method selected was Enterprise Architecture together with Enterprise Architecture Analysis research results and tools from the Industrial Information and Control Systems ...

  4. A modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array

    International Nuclear Information System (INIS)

    Liang, Guanhao; Wang, Yancheng; Mei, Deqing; Xi, Kailun; Chen, Zichen

    2015-01-01

    This paper presents a modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array, which utilizes solid polydimethylsiloxane (PDMS) film as the dielectric layer. To predict the deformation of the sensing unit and capacitance changes, each sensing unit is simplified into a three-layer plate structure and divided into central, edge and corner regions. The plate structure and the three regions are studied by the general and modified models, respectively. For experimental validation, the capacitive tactile sensor array with 8  ×  8 (= 64) sensing units is fabricated. Experiments are conducted by measuring the capacitance changes versus applied external forces and compared with the general and modified models’ predictions. For the developed tactile sensor array, the sensitivity predicted by the modified analytical model is 1.25%/N, only 0.8% discrepancy from the experimental measurement. Results demonstrate that the modified analytical model can accurately predict the sensing performance of the sensor array and could be utilized for model-based optimal capacitive tactile sensor array design. (paper)

  5. A model based on soil structural aspects describing the fate of genetically modified bacteria in soil

    NARCIS (Netherlands)

    Hoeven, van der N.; Elsas, van J.D.; Heijnen, C.E.

    1996-01-01

    A computer simulation model was developed which describes growth and competition of bacteria in the soil environment. In the model, soil was assumed to contain millions of pores of a few different size classes. An introduced bacterial strain, e.g. a genetically modified micro-organism (GEMMO), was

  6. Codeswitching and Generative Grammar: A Critique of the MLF Model and Some Remarks on "Modified Minimalism"

    Science.gov (United States)

    MacSwan, Jeff

    2005-01-01

    This article presents an empirical and theoretical critique of the Matrix Language Frame (MLF) model (Myers-Scotton, 1993; Myers-Scotton and Jake, 2001), and includes a response to Jake, Myers-Scotton and Gross's (2002) (JMSG) critique of MacSwan (1999, 2000) and reactions to their revision of the MLF model as a "modified minimalist approach." The…

  7. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches.

    Science.gov (United States)

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-10-23

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%-1.5%, in terms of shear performance.

  8. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches

    Directory of Open Access Journals (Sweden)

    Joo-Won Kang

    2013-10-01

    Full Text Available Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%–1.5%, in terms of shear performance.

  9. Comparison of Nonlinear Model Results Using Modified Recorded and Synthetic Ground Motions

    International Nuclear Information System (INIS)

    Spears, Robert E.; Wilkins, J. Kevin

    2011-01-01

    A study has been performed that compares results of nonlinear model runs using two sets of earthquake ground motion time histories that have been modified to fit the same design response spectra. The time histories include applicable modified recorded earthquake ground motion time histories and synthetic ground motion time histories. The modified recorded earthquake ground motion time histories are modified from time history records that are selected based on consistent magnitude and distance. The synthetic ground motion time histories are generated using appropriate Fourier amplitude spectrums, Arias intensity, and drift correction. All of the time history modification is performed using the same algorithm to fit the design response spectra. The study provides data to demonstrate that properly managed synthetic ground motion time histories are reasonable for use in nonlinear seismic analysis.

  10. Influence of georeference for saturated excess overland flow modelling using 3D volumetric soft geo-objects

    Science.gov (United States)

    Izham, Mohamad Yusoff; Muhamad Uznir, Ujang; Alias, Abdul Rahman; Ayob, Katimon; Wan Ruslan, Ismail

    2011-04-01

    Existing 2D data structures are often insufficient for analysing the dynamism of saturation excess overland flow (SEOF) within a basin. Moreover, all stream networks and soil surface structures in GIS must be preserved within appropriate projection plane fitting techniques known as georeferencing. Inclusion of 3D volumetric structure of the current soft geo-objects simulation model would offer a substantial effort towards representing 3D soft geo-objects of SEOF dynamically within a basin by visualising saturated flow and overland flow volume. This research attempts to visualise the influence of a georeference system towards the dynamism of overland flow coverage and total overland flow volume generated from the SEOF process using VSG data structure. The data structure is driven by Green-Ampt methods and the Topographic Wetness Index (TWI). VSGs are analysed by focusing on spatial object preservation techniques of the conformal-based Malaysian Rectified Skew Orthomorphic (MRSO) and the equidistant-based Cassini-Soldner projection plane under the existing geodetic Malaysian Revised Triangulation 1948 (MRT48) and the newly implemented Geocentric Datum for Malaysia (GDM2000) datum. The simulated result visualises deformation of SEOF coverage under different georeference systems via its projection planes, which delineate dissimilar computation of SEOF areas and overland flow volumes. The integration of Georeference, 3D GIS and the saturation excess mechanism provides unifying evidence towards successful landslide and flood disaster management through envisioning the streamflow generating process (mainly SEOF) in a 3D environment.

  11. Cellular and molecular modifier pathways in tauopathies: the big picture from screening invertebrate models.

    Science.gov (United States)

    Hannan, Shabab B; Dräger, Nina M; Rasse, Tobias M; Voigt, Aaron; Jahn, Thomas R

    2016-04-01

    Abnormal tau accumulations were observed and documented in post-mortem brains of patients affected by Alzheimer's disease (AD) long before the identification of mutations in the Microtubule-associated protein tau (MAPT) gene, encoding the tau protein, in a different neurodegenerative disease called Frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17). The discovery of mutations in the MAPT gene associated with FTDP-17 highlighted that dysfunctions in tau alone are sufficient to cause neurodegeneration. Invertebrate models have been diligently utilized in investigating tauopathies, contributing to the understanding of cellular and molecular pathways involved in disease etiology. An important discovery came with the demonstration that over-expression of human tau in Drosophila leads to premature mortality and neuronal dysfunction including neurodegeneration, recapitulating some key neuropathological features of the human disease. The simplicity of handling invertebrate models combined with the availability of a diverse range of experimental resources make these models, in particular Drosophila a powerful invertebrate screening tool. Consequently, several large-scale screens have been performed using Drosophila, to identify modifiers of tau toxicity. The screens have revealed not only common cellular and molecular pathways, but in some instances the same modifier has been independently identified in two or more screens suggesting a possible role for these modifiers in regulating tau toxicity. The purpose of this review is to discuss the genetic modifier screens on tauopathies performed in Drosophila and C. elegans models, and to highlight the common cellular and molecular pathways that have emerged from these studies. Here, we summarize results of tau toxicity screens providing mechanistic insights into pathological alterations in tauopathies. Key pathways or modifiers that have been identified are associated with a broad range of processes

  12. A modified Galam’s model for word-of-mouth information exchange

    Science.gov (United States)

    Ellero, Andrea; Fasano, Giovanni; Sorato, Annamaria

    2009-09-01

    In this paper we analyze the stochastic model proposed by Galam in [S. Galam, Modelling rumors: The no plane Pentagon French hoax case, Physica A 320 (2003), 571-580], for information spreading in a ‘word-of-mouth’ process among agents, based on a majority rule. Using the communications rules among agents defined in the above reference, we first perform simulations of the ‘word-of-mouth’ process and compare the results with the theoretical values predicted by Galam’s model. Some dissimilarities arise in particular when a small number of agents is considered. We find motivations for these dissimilarities and suggest some enhancements by introducing a new parameter dependent model. We propose a modified Galam’s scheme which is asymptotically coincident with the original model in the above reference. Furthermore, for relatively small values of the parameter, we provide a numerical experience proving that the modified model often outperforms the original one.

  13. Advanced diffusion model in compacted bentonite based on modified Poisson-Boltzmann equations

    International Nuclear Information System (INIS)

    Yotsuji, K.; Tachi, Y.; Nishimaki, Y.

    2012-01-01

    Document available in extended abstract form only. Diffusion and sorption of radionuclides in compacted bentonite are the key processes in the safe geological disposal of radioactive waste. JAEA has developed the integrated sorption and diffusion (ISD) model for compacted bentonite by coupling the pore water chemistry, sorption and diffusion processes in consistent way. The diffusion model accounts consistently for cation excess and anion exclusion in narrow pores in compacted bentonite by the electric double layer (EDL) theory. The firstly developed ISD model could predict the diffusivity of the monovalent cation/anion in compacted bentonite as a function of dry density. This ISD model was modified by considering the visco-electric effect, and applied for diffusion data for various radionuclides measured under wide range of conditions (salinity, density, etc.). This modified ISD model can give better quantitative agreement with diffusion data for monovalent cation/anion, however, the model predictions still disagree with experimental data for multivalent cation and complex species. In this study we extract the additional key factors influencing diffusion model in narrow charged pores, and the effects of these factors were investigated to reach a better understanding of diffusion processes in compacted bentonite. We investigated here the dielectric saturation effect and the excluded volume effect into the present ISD model and numerically solved these modified Poisson-Boltzmann equations. In the vicinity of the negatively charged clay surfaces, it is necessary to evaluate concentration distribution of electrolytes considering the dielectric saturation effects. The Poisson-Boltzmann (P-B) equation coupled with the dielectric saturation effects was solved numerically by using Runge-Kutta and Shooting methods. Figure 1(a) shows the concentration distributions of Na + as numerical solutions of the modified and original P-B equations for 0.01 M pore water, 800 kg m -3

  14. Regionalization of the Modified Bartlett-Lewis Rectangular Pulse Stochastic Rainfall Model

    OpenAIRE

    Dongkyun Kim; Francisco Olivera; Huidae Cho; Scott A. Socolofsky

    2013-01-01

    Parameters of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP) stochastic rainfall simulation model were regionalized across the contiguous United States. Three thousand four hundred forty-four National Climate Data Center (NCDC) rain gauges were used to obtain spatial and seasonal patterns of the model parameters. The MBLRP model was calibrated to minimize the discrepancy between the precipitation depth statistics between the observed and MBLRP-generated precipitation time series. These...

  15. COLA with scale-dependent growth: applications to screened modified gravity models

    Energy Technology Data Exchange (ETDEWEB)

    Winther, Hans A.; Koyama, Kazuya; Wright, Bill S. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Manera, Marc [Centre for Theoretical Cosmology, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Zhao, Gong-Bo, E-mail: hans.a.winther@gmail.com, E-mail: kazuya.koyama@port.ac.uk, E-mail: manera.work@gmail.com, E-mail: bill.wright@port.ac.uk, E-mail: gong-bo.Zhao@port.ac.uk [National Astronomy Observatories, Chinese Academy of Science, Beijing, 100012 (China)

    2017-08-01

    We present a general parallelized and easy-to-use code to perform numerical simulations of structure formation using the COLA (COmoving Lagrangian Acceleration) method for cosmological models that exhibit scale-dependent growth at the level of first and second order Lagrangian perturbation theory. For modified gravity theories we also include screening using a fast approximate method that covers all the main examples of screening mechanisms in the literature. We test the code by comparing it to full simulations of two popular modified gravity models, namely f ( R ) gravity and nDGP, and find good agreement in the modified gravity boost-factors relative to ΛCDM even when using a fairly small number of COLA time steps.

  16. Modified polarized geometrical attenuation model for bidirectional reflection distribution function based on random surface microfacet theory.

    Science.gov (United States)

    Liu, Hong; Zhu, Jingping; Wang, Kai

    2015-08-24

    The geometrical attenuation model given by Blinn was widely used in the geometrical optics bidirectional reflectance distribution function (BRDF) models. Blinn's geometrical attenuation model based on symmetrical V-groove assumption and ray scalar theory causes obvious inaccuracies in BRDF curves and negatives the effects of polarization. Aiming at these questions, a modified polarized geometrical attenuation model based on random surface microfacet theory is presented by combining of masking and shadowing effects and polarized effect. The p-polarized, s-polarized and unpolarized geometrical attenuation functions are given in their separate expressions and are validated with experimental data of two samples. It shows that the modified polarized geometrical attenuation function reaches better physical rationality, improves the precision of BRDF model, and widens the applications for different polarization.

  17. Modified hyperbolic sine model for titanium dioxide-based memristive thin films

    Science.gov (United States)

    Abu Bakar, Raudah; Syahirah Kamarozaman, Nur; Fazlida Hanim Abdullah, Wan; Herman, Sukreen Hana

    2018-03-01

    Since the emergence of memristor as the newest fundamental circuit elements, studies on memristor modeling have been evolved. To date, the developed models were based on the linear model, linear ionic drift model using different window functions, tunnelling barrier model and hyperbolic-sine function based model. Although using hyperbolic-sine function model could predict the memristor electrical properties, the model was not well fitted to the experimental data. In order to improve the performance of the hyperbolic-sine function model, the state variable equation was modified. On the one hand, the addition of window function cannot provide an improved fitting. By multiplying the Yakopcic’s state variable model to Chang’s model on the other hand resulted in the closer agreement with the TiO2 thin film experimental data. The percentage error was approximately 2.15%.

  18. [Three dimensional finite element model of a modified posterior cervical single open-door laminoplasty].

    Science.gov (United States)

    Wang, Q; Yang, Y; Fei, Q; Li, D; Li, J J; Meng, H; Su, N; Fan, Z H; Wang, B Q

    2017-06-06

    Objective: To build a three-dimensional finite element models of a modified posterior cervical single open-door laminoplasty with short-segmental lateral mass screws fusion. Methods: The C(2)-C(7) segmental data were obtained from computed tomography (CT) scans of a male patient with cervical spondylotic myelopathy and spinal stenosis.Three-dimensional finite element models of a modified cervical single open-door laminoplasty (before and after surgery) were constructed by the combination of software package MIMICS, Geomagic and ABAQUS.The models were composed of bony vertebrae, articulating facets, intervertebral disc and associated ligaments.The loads of moments 1.5Nm at different directions (flexion, extension, lateral bending and axial rotation)were applied at preoperative model to calculate intersegmental ranges of motion.The results were compared with the previous studies to verify the validation of the models. Results: Three-dimensional finite element models of the modified cervical single open- door laminoplasty had 102258 elements (preoperative model) and 161 892 elements (postoperative model) respectively, including C(2-7) six bony vertebraes, C(2-3)-C(6-7) five intervertebral disc, main ligaments and lateral mass screws.The intersegmental responses at the preoperative model under the loads of moments 1.5 Nm at different directions were similar to the previous published data. Conclusion: Three-dimensional finite element models of the modified cervical single open- door laminoplasty were successfully established and had a good biological fidelity, which can be used for further study.

  19. Pion Susceptibilities of the Vacuum in a Modified Global Colour Symmetry Model

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; WU Xiao-Hua; DING Xiao-Ping; L0 Xiao-Fu; ZHAO En-Guang

    2001-01-01

    Based on a modified version of the global color symmetry model, the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation. Comparison with the previous estimations has been given.

  20. Lattice dynamics of aluminium, lead and thorium on modified Bhatia's model

    International Nuclear Information System (INIS)

    Bertolo, L.A.; Shukla, M.M.

    1975-01-01

    Phonon dispersion relations along the three principal symmetry directions as well as lattice heat capacities of aluminium, lead and thorium have been calculated on the basis of modified Bathia's model. The calculated results are found to show reasonable agreements with the experimental observations

  1. Black Hole Entropy Calculation in a Modified Thin Film Model Jingyi ...

    Indian Academy of Sciences (India)

    Abstract. The thin film model is modified to calculate the black hole entropy. The difference from the original method is that the Parikh–. Wilczek tunnelling framework is introduced and the self-gravitation of the emission particles is taken into account. In terms of our improvement, if the entropy is still proportional to the area, ...

  2. A holistic water depth simulation model for small ponds

    Science.gov (United States)

    Ali, Shakir; Ghosh, Narayan C.; Mishra, P. K.; Singh, R. K.

    2015-10-01

    Estimation of time varying water depth and time to empty of a pond is prerequisite for comprehensive and coordinated planning of water resource for its effective utilization. A holistic water depth simulation (HWDS) and time to empty (TE) model for small, shallow ephemeral ponds have been derived by employing the generalized model based on the Green-Ampt equation in the basic water balance equation. The HWDS model includes time varying rainfall, runoff, surface water evaporation, outflow and advancement of wetting front length as external inputs. The TE model includes two external inputs; surface water evaporation and advancement of wetting front length. Both the models also consider saturated hydraulic conductivity and fillable porosity of the pond's bed material as their parameters. The solution of the HWDS model involved numerical iteration in successive time intervals. The HWDS model has successfully evaluated with 3 years of field data from two small ponds located within a watershed in a semi-arid region in western India. The HWDS model simulated time varying water depth in the ponds with high accuracy as shown by correlation coefficient (R2 ⩾ 0.9765), index of agreement (d ⩾ 0.9878), root mean square errors (RMSE ⩽ 0.20 m) and percent bias (PB ⩽ 6.23%) for the pooled data sets of the measured and simulated water depth. The statistical F and t-tests also confirmed the reliability of the HWDS model at probability level, p ⩽ 0.0001. The response of the TE model showed its ability to estimate the time to empty the ponds. An additional field calibration and validation of the HWDS and TE models with observed field data in varied hydro-climatic conditions could be conducted to increase the applicability and credibility of the models.

  3. Modified two-layer social force model for emergency earthquake evacuation

    Science.gov (United States)

    Zhang, Hao; Liu, Hong; Qin, Xin; Liu, Baoxi

    2018-02-01

    Studies of crowd behavior with related research on computer simulation provide an effective basis for architectural design and effective crowd management. Based on low-density group organization patterns, a modified two-layer social force model is proposed in this paper to simulate and reproduce a group gathering process. First, this paper studies evacuation videos from the Luan'xian earthquake in 2012, and extends the study of group organization patterns to a higher density. Furthermore, taking full advantage of the strength in crowd gathering simulations, a new method on grouping and guidance is proposed while using crowd dynamics. Second, a real-life grouping situation in earthquake evacuation is simulated and reproduced. Comparing with the fundamental social force model and existing guided crowd model, the modified model reduces congestion time and truly reflects group behaviors. Furthermore, the experiment result also shows that a stable group pattern and a suitable leader could decrease collision and allow a safer evacuation process.

  4. Kink-antikink interactions in a modified sine-Gordon model

    International Nuclear Information System (INIS)

    Peyrard, M.; Campbell, D.K.; Los Alamos National Lab., NM

    1983-01-01

    We study numerically the interactions of a kink (K) and an antikink (anti K) in a parametrically modified sine-Gordon model with potential V(PHI)=(1-r) 2 (1-cos PHI)/(1+r 2 +2r cos PHI). As the parameter r is varied from the pure sine-Gordon case (r=0) to values for which the model is not completely integrable (rnot=0), we find that a rich structure arises in the Kanti K collisions. For some regions of r(-0.20 4 model, and we show that the theory recently suggested for these collisions also applies quantitatively to the modified sine-Gordon model. In other regions of r we observe new scattering phenomena, which we present in detail numerically and discuss in a qualitative manner analytically. (orig.)

  5. Identification of total reversible cysteine oxidation in an atherosclerosis model using a modified biotin switch assay.

    Science.gov (United States)

    Li, Ru; Huang, Jiqing; Kast, Juergen

    2015-05-01

    Oxidative stress due to the imbalance of reactive oxygen species (ROS) and the resulting reversible cysteine oxidation (CysOX) are involved in the early proatherogenic aspect of atherosclerosis. Given that the corresponding redox signaling pathways are still unclear, a modified biotin switch assay was developed to quantify the reversible CysOX in an atherosclerosis model established by using a monocytic cell line treated with platelet releasate. The accumulation of ROS was observed in the model system and validated in human primary monocytes. Through the application of the modified biotin switch assay, we obtained the first reversible CysOX proteome for this model. A total of 75 peptides, corresponding to 53 proteins, were quantified with oxidative modification. The bioinformatics analysis of these CysOX-containing proteins highlighted biological processes including glycolysis, cytoskeleton arrangement, and redox regulation. Moreover, the reversible oxidation of three glycolysis enzymes was observed using this method, and the regulation influence was verified by an enzyme activity assay. NADPH oxidase (NOX) inhibition treatment, in conjunction with the modified biotin switch method, was used to evaluate the global CysOX status. In conclusion, this versatile modified biotin switch assay provides an approach for the quantification of all reversible CysOX and for the study of redox signaling in atherosclerosis as well as in diseases in other biological systems.

  6. Modified Continuum Mechanics Modeling on Size-Dependent Properties of Piezoelectric Nanomaterials: A Review

    Directory of Open Access Journals (Sweden)

    Zhi Yan

    2017-01-01

    Full Text Available Piezoelectric nanomaterials (PNs are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the particular size. A large amount of efforts have been devoted to studying the size-dependent properties of PNs by using experimental characterization, atomistic simulation and continuum mechanics modeling with the consideration of the scale features of the nanomaterials. This paper reviews the recent progresses and achievements in the research on the continuum mechanics modeling of the size-dependent mechanical and physical properties of PNs. We start from the fundamentals of the modified continuum mechanics models for PNs, including the theories of surface piezoelectricity, flexoelectricity and non-local piezoelectricity, with the introduction of the modified piezoelectric beam and plate models particularly for nanostructured piezoelectric materials with certain configurations. Then, we give a review on the investigation of the size-dependent properties of PNs by using the modified continuum mechanics models, such as the electromechanical coupling, bending, vibration, buckling, wave propagation and dynamic characteristics. Finally, analytical modeling and analysis of nanoscale actuators and energy harvesters based on piezoelectric nanostructures are presented.

  7. A model for phosphate glass topology considering the modifying ion sub-network

    DEFF Research Database (Denmark)

    Hermansen, Christian; Mauro, J.C.; Yue, Yuanzheng

    2014-01-01

    In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent with availa......In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent...... with available structural data by NMR and molecular dynamics simulation and dynamic data such glass transition temperature (Tg) and liquid fragility (m). Alkali phosphate glasses are exemplary systems for developing constraint model since the modifying cation network plays an important role besides the primary...... phosphate network. The proposed topological model predicts the changing trend of the Tg and m with increasing alkali oxide content for alkali phosphate glasses, including an anomalous minimum at around 20 mol% alkali oxide content. We find that the minimum in Tg and m is caused by increased connectivity...

  8. Modified Continuum Mechanics Modeling on Size-Dependent Properties of Piezoelectric Nanomaterials: A Review.

    Science.gov (United States)

    Yan, Zhi; Jiang, Liying

    2017-01-26

    Piezoelectric nanomaterials (PNs) are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS) because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the particular size. A large amount of efforts have been devoted to studying the size-dependent properties of PNs by using experimental characterization, atomistic simulation and continuum mechanics modeling with the consideration of the scale features of the nanomaterials. This paper reviews the recent progresses and achievements in the research on the continuum mechanics modeling of the size-dependent mechanical and physical properties of PNs. We start from the fundamentals of the modified continuum mechanics models for PNs, including the theories of surface piezoelectricity, flexoelectricity and non-local piezoelectricity, with the introduction of the modified piezoelectric beam and plate models particularly for nanostructured piezoelectric materials with certain configurations. Then, we give a review on the investigation of the size-dependent properties of PNs by using the modified continuum mechanics models, such as the electromechanical coupling, bending, vibration, buckling, wave propagation and dynamic characteristics. Finally, analytical modeling and analysis of nanoscale actuators and energy harvesters based on piezoelectric nanostructures are presented.

  9. Modified k-l model and its ability to simulate supersonic axisymmetric turbulent flows

    International Nuclear Information System (INIS)

    Ahmadikia, H.; Shirani, E.

    2001-05-01

    The k-l turbulence model is a promising two-equation model. In this paper, the k and l model equations were derived from k-kl incompressible and one-equation turbulent models. Then the model was modified for compressible and transitional flows, and was applied to simulate supersonic axisymmetric flows over Hollow cylinder flare an hyperboloid flare bodies. The results were compared with the results obtained for the same flows experimentally as well as k-ε, k-ω and Baldwin-Lomax models. It was shown that the k-l model produces good results compared with experimental data and numerical data obtained when other turbulence models were used. It gives better results than k-ω and k-ε models in some cases. (author)

  10. Thermoacoustic model of a modified free piston Stirling engine with a thermal buffer tube

    International Nuclear Information System (INIS)

    Yang, Qin; Luo, Ercang; Dai, Wei; Yu, Guoyao

    2012-01-01

    This article presents a modified free-piston Stirling heat engine configuration in which a thermal buffer tube is added to sandwich between the hot and cold heat exchangers. Such a modified configuration may lead to an easier fabrication and lighter weight of a free piston. To analyze the thermodynamic performance of the modified free piston Stirling heat engine, thermoacoustic theory is used. In the thermoacoustic modelling, the regenerator, the free piston, and the thermal buffer tube are given at first. Then, based on linear thermoacoustic network theory, the thermal and thermodynamic networks are presented to characterize acoustic pressure and volume flow rate distributions at different interfaces, and the global performance such as the power output, the heat input and the thermal efficiency. A free piston Stirling heat engine with several hundreds of watts mechanical power output is selected as an example. The typical operating and structure parameters are as follows: frequency around 50 Hz, mean pressure around 3.0 MPa, and a diameter of free piston around 50 mm. From the analysis, it was found that the modified free-piston Stirling heat engine has almost the same thermodynamic performance as the original design, which indicates that the modified configuration is worthy to develop in future because of its mechanical simplicity and reliability.

  11. Substructure evolution of Zircaloy-4 during creep and implications for the Modified Jogged-Screw model

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, B.M., E-mail: morrow@lanl.gov [The Ohio State University, 2041 College Rd., 477 Watts Hall, Columbus, OH 43210 (United States); Los Alamos National Laboratory, P.O. Box 1663, MS G755, Los Alamos, NM 87545 (United States); Kozar, R.W.; Anderson, K.R. [Bettis Laboratory, Bechtel Marine Propulsion Corp., West Mifflin, PA 15122 (United States); Mills, M.J., E-mail: millsmj@mse.osu.edu [The Ohio State University, 2041 College Rd., 477 Watts Hall, Columbus, OH 43210 (United States)

    2016-05-17

    Several specimens of Zircaloy-4 were creep tested at a single stress-temperature condition, and interrupted at different accumulated strain levels. Substructural observations were performed using bright field scanning transmission electron microscopy (BF STEM). The dislocation substructure was characterized to ascertain how creep strain evolution impacts the Modified Jogged-Screw (MJS) model, which has previously been utilized to predict steady-state strain rates in Zircaloy-4. Special attention was paid to the evolution of individual model parameters with increasing strain. Results of model parameter measurements are reported and discussed, along with possible extensions to the MJS model.

  12. Holographik, the k-essential approach to interactive models with modified holographic Ricci dark energy

    Energy Technology Data Exchange (ETDEWEB)

    Forte, Monica [Universidad de Buenos Aires, Departamento de Fisica, Facultad de ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2016-12-15

    We make a scalar representation of interactive models with cold dark matter and modified holographic Ricci dark energy through unified models driven by scalar fields with non-canonical kinetic term. These models are applications of the formalism of exotic k-essences generated by the global description of cosmological models with two interactive fluids in the dark sector and in these cases they correspond to the usual k-essences. The formalism is applied to the cases of constant potential in Friedmann-Robertson-Walker geometries. (orig.)

  13. Modeling the grazing effect on dry grassland carbon cycling with modified Biome-BGC grazing model

    Science.gov (United States)

    Luo, Geping; Han, Qifei; Li, Chaofan; Yang, Liao

    2014-05-01

    Identifying the factors that determine the carbon source/sink strength of ecosystems is important for reducing uncertainty in the global carbon cycle. Arid grassland ecosystems are a widely distributed biome type in Xinjiang, Northwest China, covering approximately one-fourth the country's land surface. These grasslands are the habitat for many endemic and rare plant and animal species and are also used as pastoral land for livestock. Using the modified Biome-BGC grazing model, we modeled carbon dynamics in Xinjiang for grasslands that varied in grazing intensity. In general, this regional simulation estimated that the grassland ecosystems in Xinjiang acted as a net carbon source, with a value of 0.38 Pg C over the period 1979-2007. There were significant effects of grazing on carbon dynamics. An over-compensatory effect in net primary productivity (NPP) and vegetation carbon (C) stock was observed when grazing intensity was lower than 0.40 head/ha. Grazing resulted in a net carbon source of 23.45 g C m-2 yr-1, which equaled 0.37 Pg in Xinjiang in the last 29 years. In general, grazing decreased vegetation C stock, while an increasing trend was observed with low grazing intensity. The soil C increased significantly (17%) with long-term grazing, while the soil C stock exhibited a steady trend without grazing. These findings have implications for grassland ecosystem management as it relates to carbon sequestration and climate change mitigation, e.g., removal of grazing should be considered in strategies that aim to increase terrestrial carbon sequestrations at local and regional scales. One of the greatest limitations in quantifying the effects of herbivores on carbon cycling is identifying the grazing systems and intensities within a given region. We hope our study emphasizes the need for large-scale assessments of how grazing impacts carbon cycling. Most terrestrial ecosystems in Xinjiang have been affected by disturbances to a greater or lesser extent in the past

  14. A Cost-Effective Tracking Algorithm for Hypersonic Glide Vehicle Maneuver Based on Modified Aerodynamic Model

    Directory of Open Access Journals (Sweden)

    Yu Fan

    2016-10-01

    Full Text Available In order to defend the hypersonic glide vehicle (HGV, a cost-effective single-model tracking algorithm using Cubature Kalman filter (CKF is proposed in this paper based on modified aerodynamic model (MAM as process equation and radar measurement model as measurement equation. In the existing aerodynamic model, the two control variables attack angle and bank angle cannot be measured by the existing radar equipment and their control laws cannot be known by defenders. To establish the process equation, the MAM for HGV tracking is proposed by using additive white noise to model the rates of change of the two control variables. For the ease of comparison several multiple model algorithms based on CKF are presented, including interacting multiple model (IMM algorithm, adaptive grid interacting multiple model (AGIMM algorithm and hybrid grid multiple model (HGMM algorithm. The performances of these algorithms are compared and analyzed according to the simulation results. The simulation results indicate that the proposed tracking algorithm based on modified aerodynamic model has the best tracking performance with the best accuracy and least computational cost among all tracking algorithms in this paper. The proposed algorithm is cost-effective for HGV tracking.

  15. Facilitating political decisions using species distribution models to assess restoration measures in heavily modified estuaries.

    Science.gov (United States)

    Heuner, Maike; Weber, Arnd; Schröder, Uwe; Kleinschmit, Birgit; Schröder, Boris

    2016-09-15

    The European Water Framework Directive requires a good ecological potential for heavily modified water bodies. This standard has not been reached for most large estuaries by 2015. Management plans for estuaries fall short in linking implementations between restoration measures and underlying spatial analyses. The distribution of emergent macrophytes - as an indicator of habitat quality - is here used to assess the ecological potential. Emergent macrophytes are capable of settling on gentle tidal flats where hydrodynamic stress is comparatively low. Analyzing their habitats based on spatial data, we set up species distribution models with 'elevation relative to mean high water', 'mean bank slope', and 'length of bottom friction' from shallow water up to the vegetation belt as key predictors representing hydrodynamic stress. Effects of restoration scenarios on habitats were assessed applying these models. Our findings endorse species distribution models as crucial spatial planning tools for implementing restoration measures in modified estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A modified Johnson–Cook model of dynamic tensile behaviors for 7075-T6 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ding-Ni, E-mail: siping4840@126.com [The College of Information, Mechanical and Electrical Engineering, Shanghai Normal University, Shanghai 200234 (China); Shangguan, Qian-Qian [The College of Information, Mechanical and Electrical Engineering, Shanghai Normal University, Shanghai 200234 (China); Xie, Can-Jun [Commercial Aircraft Corporation of China, Ltd., Shanghai 200120 (China); Liu, Fu [Shanghai Aircraft Design and Research Institute of COMAC, Shanghai 201210 (China)

    2015-01-15

    Highlights: • The dynamic mechanical behaviors at various strain rates were measured. • The strain rate hardening effect of 7075-T6 aluminum alloy is significant. • A new Johnson–Cook constitutive model of 7075-T6 aluminum alloy was obtained. • Numerical simulations of tensile tests at different rates were conducted. • Accuracy of the modified Johnson–Cook constitutive equation was proved. - Abstract: The dynamic mechanical behaviors of 7075-T6 aluminum alloy at various strain rates were measured by dynamic tensile tests using the electronic universal testing machine, high velocity testing system and split Hopkinson tensile bar (SHTB). Stress–strain curves at different rates were obtained. The results show that the strain rate hardening effect of 7075-T6 aluminum alloy is significant. By modifying the strain rate hardening term in the Johnson–Cook constitutive model, a new Johnson–Cook (JC) constitutive model of 7075-T6 aluminum alloy was obtained. The improved Johnson–Cook model matched the experiment results very well. With the Johnson–Cook constitutive model, numerical simulations of tensile tests at different rates for 7075-T6 aluminum alloy were conducted. According to tensile loading and stress–strain relation of 7075-T6 aluminum alloy, calculation results were compared with experimental results. Accuracy of the modified Johnson–Cook constitutive equation was further proved.

  17. A modified Johnson–Cook model of dynamic tensile behaviors for 7075-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Zhang, Ding-Ni; Shangguan, Qian-Qian; Xie, Can-Jun; Liu, Fu

    2015-01-01

    Highlights: • The dynamic mechanical behaviors at various strain rates were measured. • The strain rate hardening effect of 7075-T6 aluminum alloy is significant. • A new Johnson–Cook constitutive model of 7075-T6 aluminum alloy was obtained. • Numerical simulations of tensile tests at different rates were conducted. • Accuracy of the modified Johnson–Cook constitutive equation was proved. - Abstract: The dynamic mechanical behaviors of 7075-T6 aluminum alloy at various strain rates were measured by dynamic tensile tests using the electronic universal testing machine, high velocity testing system and split Hopkinson tensile bar (SHTB). Stress–strain curves at different rates were obtained. The results show that the strain rate hardening effect of 7075-T6 aluminum alloy is significant. By modifying the strain rate hardening term in the Johnson–Cook constitutive model, a new Johnson–Cook (JC) constitutive model of 7075-T6 aluminum alloy was obtained. The improved Johnson–Cook model matched the experiment results very well. With the Johnson–Cook constitutive model, numerical simulations of tensile tests at different rates for 7075-T6 aluminum alloy were conducted. According to tensile loading and stress–strain relation of 7075-T6 aluminum alloy, calculation results were compared with experimental results. Accuracy of the modified Johnson–Cook constitutive equation was further proved

  18. Modified kinetic-hydraulic UASB reactor model for treatment of wastewater containing biodegradable organic substrates.

    Science.gov (United States)

    El-Seddik, Mostafa M; Galal, Mona M; Radwan, A G; Abdel-Halim, Hisham S

    2016-01-01

    This paper addresses a modified kinetic-hydraulic model for up-flow anaerobic sludge blanket (UASB) reactor aimed to treat wastewater of biodegradable organic substrates as acetic acid based on Van der Meer model incorporated with biological granules inclusion. This dynamic model illustrates the biomass kinetic reaction rate for both direct and indirect growth of microorganisms coupled with the amount of biogas produced by methanogenic bacteria in bed and blanket zones of reactor. Moreover, the pH value required for substrate degradation at the peak specific growth rate of bacteria is discussed for Andrews' kinetics. The sensitivity analyses of biomass concentration with respect to fraction of volume of reactor occupied by granules and up-flow velocity are also demonstrated. Furthermore, the modified mass balance equations of reactor are applied during steady state using Newton Raphson technique to obtain a suitable degree of freedom for the modified model matching with the measured results of UASB Sanhour wastewater treatment plant in Fayoum, Egypt.

  19. Modified two-fluid model for the two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Sun Xiaodong; Ishii, Mamoru; Kelly, Joseph M.

    2003-01-01

    This paper presents a modified two-fluid model that is ready to be applied in the approach of the two-group interfacial area transport equation. The two-group interfacial area transport equation was developed to provide a mechanistic constitutive relation for the interfacial area concentration in the two-fluid model. In the two-group transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 while cap/slug/churn-turbulent bubbles as Group 2. Therefore, this transport equation can be employed in the flow regimes spanning from bubbly, cap bubbly, slug to churn-turbulent flows. However, the introduction of the two groups of bubbles requires two gas velocity fields. Yet it is not practical to solve two momentum equations for the gas phase alone. In the current modified two-fluid model, a simplified approach is proposed. The momentum equation for the averaged velocity of both Group-1 and Group-2 bubbles is retained. By doing so, the velocity difference between Group-1 and Group-2 bubbles needs to be determined. This may be made either based on simplified momentum equations for both Group-1 and Group-2 bubbles or by a modified drift-flux model

  20. Plane symmetric cosmological micro model in modified theory of Einstein’s general relativity

    Directory of Open Access Journals (Sweden)

    Panigrahi U.K.

    2003-01-01

    Full Text Available In this paper, we have investigated an anisotropic homogeneous plane symmetric cosmological micro-model in the presence of massless scalar field in modified theory of Einstein's general relativity. Some interesting physical and geometrical aspects of the model together with singularity in the model are discussed. Further, it is shown that this theory is valid and leads to Ein­stein's theory as the coupling parameter λ →>• 0 in micro (i.e. quantum level in general.

  1. Giant halos in medium nuclei within modified relativistic mean field (MRMF) model

    Energy Technology Data Exchange (ETDEWEB)

    Nugraha, A. M., E-mail: alpi.mahisha@gmail.com; Sulaksono, A. [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Sumaryada, T. [Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia)

    2016-04-19

    The large number of neutrons in a region beyond a closed shell core indicates the presence of giant halos in nuclei. In this work, by using the Rotival method within a modified relativistic mean field (MRMF) model, we predict theoretically the formation of giant halos in Cr and Zr isotopes. The MRMF model is a modification of standard RMF model augmented with isoscalar and isovector tensor terms, isovector-isoscalar vector cross coupling term and electromagnetic exchange term for Coulomb interaction in local density approximation (LDA).

  2. Late time acceleration in a non-commutative model of modified cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Malekolkalami, B., E-mail: b.malakolkalami@uok.ac.ir [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Atazadeh, K., E-mail: atazadeh@azaruniv.ac.ir [Department of Physics, Azarbaijan Shahid Madani University, 53714-161, Tabriz (Iran, Islamic Republic of); Vakili, B., E-mail: b-vakili@iauc.ac.ir [Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2014-12-12

    We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.

  3. Numerical simulation of binary collisions using a modified surface tension model with particle method

    International Nuclear Information System (INIS)

    Sun Zhongguo; Xi Guang; Chen Xi

    2009-01-01

    The binary collision of liquid droplets is of both practical importance and fundamental value in computational fluid mechanics. We present a modified surface tension model within the moving particle semi-implicit (MPS) method, and carry out two-dimensional simulations to investigate the mechanisms of coalescence and separation of the droplets during binary collision. The modified surface tension model improves accuracy and convergence. A mechanism map is established for various possible deformation pathways encountered during binary collision, as the impact speed is varied; a new pathway is reported when the collision speed is critical. In addition, eccentric collisions are simulated and the effect of the rotation of coalesced particle is explored. The results qualitatively agree with experiments and the numerical protocol may find applications in studying free surface flows and interface deformation

  4. A modified homogeneous relaxation model for CO2 two-phase flow in vapour ejector

    International Nuclear Information System (INIS)

    Haida, M.; Palacz, M.; Smolka, J.; Nowak, A. J.; Hafner, A.; Banasiak, K.

    2016-01-01

    In this study, the homogenous relaxation model (HRM) for CO 2 flow in a two-phase ejector was modified in order to increase the accuracy of the numerical simulations The two- phase flow model was implemented on the effective computational tool called ejectorPL for fully automated and systematic computations of various ejector shapes and operating conditions. The modification of the HRM was performed by a change of the relaxation time and the constants included in the relaxation time equation based on the experimental result under the operating conditions typical for the supermarket refrigeration system. The modified HRM was compared to the HEM results, which were performed based on the comparison of motive nozzle and suction nozzle mass flow rates. (paper)

  5. Study of p-4He Total Reaction cross section using Glauber and Modified Glauber Models

    International Nuclear Information System (INIS)

    Tag El Din, I.M.A.; Taha, M.M.; Hassan, S.S.A.

    2012-01-01

    The total nuclear reaction cross-section for p - 4 He in the energy range from 25 to 1000 MeV is calculated within Glauber and modified Glauber models. The modified Glauber model is introduced via both Coulomb trajectory of the projectile and calculation of the effective radius of interaction. The effects of density dependent total cross-section and phase variation of nucleon-nucleon scattering amplitude are studied. It is pointed out that the phase variation of the nucleon-nucleon amplitude plays a significant role in describing σR at E p 2 at e = e0 = 0 and γ=2fm 2 at e = e0 = 0.17fm -3 .

  6. Late time acceleration in a non-commutative model of modified cosmology

    International Nuclear Information System (INIS)

    Malekolkalami, B.; Atazadeh, K.; Vakili, B.

    2014-01-01

    We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution

  7. A modified homogeneous relaxation model for CO2 two-phase flow in vapour ejector

    Science.gov (United States)

    Haida, M.; Palacz, M.; Smolka, J.; Nowak, A. J.; Hafner, A.; Banasiak, K.

    2016-09-01

    In this study, the homogenous relaxation model (HRM) for CO2 flow in a two-phase ejector was modified in order to increase the accuracy of the numerical simulations The two- phase flow model was implemented on the effective computational tool called ejectorPL for fully automated and systematic computations of various ejector shapes and operating conditions. The modification of the HRM was performed by a change of the relaxation time and the constants included in the relaxation time equation based on the experimental result under the operating conditions typical for the supermarket refrigeration system. The modified HRM was compared to the HEM results, which were performed based on the comparison of motive nozzle and suction nozzle mass flow rates.

  8. PRAGMATICS OF USING A MODIFIED CAPM MODEL FOR ESTIMATING COST OF EQUITY ON EMERGING MARKETS

    Directory of Open Access Journals (Sweden)

    Vitaliy Semenyuk

    2016-11-01

    Full Text Available The aim of the work is to forming pragmatic recommendations for the development and implementation the modified CAPM model in the process of estimating the equity value on emerging markets. Original CAPM model allows estimating the cost of equity on the developed capital markets. At the same time it requires the information received on the market data basis. But, as show recent empirical research, the classical model does not always produce acceptable results of the equity estimation. In addition, CAPM model in its classical form can’t be used to estimate the cost of equity for countries with emerging markets. This is due with lower efficiency in emerging markets, with lower level of liquidity and capitalization, which makes the information obtained from these markets not entirely reliable. Therefore in practice are increasingly using different modification CAPM models, that allow consider for more specific factors which affect the cost of equity. These factors, which are not considered in the classical CAPM model, include the size of the corporation and country risk. The first factor is actual for developed and emerging markets and needed to account during the equity estimation and modification the CAPM model. Country risk is associated with differences and peculiarities of the economies different countries and in the first place should be taken into account when estimating the cost of equity in emerging capital markets, which are considered by investors as more risky for investment. This factor should also be taken into account in estimating the cost of equity. Methodology In the process of constructing a modified CAPM model, theoretical and methodological provisions were used, which are set out in the work R. Banz, G. Bekaert, M. Goedhart, R. Grabowski, R. Grinold, D. Vessels, A. Damodaran, M. Dempsey, J. Zhang, R. Ibbotson, P. Kaplan, T. Koller, K. Kroner, L. Kruschwitz, M. Long, A. Lofler, G. Mandl, M. Miller, F. Modilyani, K. Nunes, D

  9. Retention of cesium by alkylammonium salt modified bentonite: experiments and modeling

    International Nuclear Information System (INIS)

    Lin, Shih-Min; Chen, Jiann-Ruey; Wang, Tsing-Hai; Teng, Shi-Ping

    2010-01-01

    Document available in extended abstract form only. Application of bentonite as engineering barriers as well as back-filled material to radioactive waste repository is widely conducted around the world. It was reported that organic-modified bentonite is able to adsorb anionic radionuclides but its sorptive capabilities toward cationic radionuclides would decrease at the same time. In order to evaluate the influence of alkyl moiety of modification reagents on sorption of cationic radionuclides, surface modification of bentonite by hexadecyltrimethyl ammonium (HTMA, 3 deg.) and by hexa-decylamine (Hamine, 1 deg.) was prepared. Their sorption capabilities were examined by Cs sorption experiments and quantified as sorption equilibrium constants (in terms of log K) by using surface complexation model MINEQL+ 4.6. In order of the decrease of sorption capability, it is observed that MX 80 > Hamine-modified > HTMA-modified bentonite. Moreover, similar to the performance of MX 80, Hamine-modified bentonite reached a sorption plateau under alkaline environments while HTMA-modified one seemed to be insensitive to the pH variation. To explain the observations, it was assumed that Cs sorption was mainly contributed by structure (= X) and edge (= SOH) sorption sites on bentonite surfaces. It was observed that the log K of structure sites of both Hamine- and HTMA-modified bentonite was more negative than that of raw bentonite. It was taken as evidence that either Hamine or HTMA species were less capable of exchanging with Cs ions than Na ions (exchangeable cation on MX 80 surfaces) do. This also implied that the sorption affinity of Hamine was greater than HTMA toward structure sites. However, it was difficult to explain the influence of organic modification on sorption at edge sorption sites. The HTMA-modified bentonite had the most negative log K value, while Hamine-modified one showed the least negative log K. it could be only explained by the structure changes of the organo

  10. Computational Modelling of Catalytic Properties and Modified Substrates of Fungal B-N-Acetylhexosaminidases

    Czech Academy of Sciences Publication Activity Database

    Kulik, Natallia; Slámová, Kristýna

    2011-01-01

    Roč. 8, č. 3 (2011), s. 270-280 ISSN 1570-193X R&D Projects: GA ČR(CZ) GAP207/11/0629; GA ČR GD305/09/H008; GA MŠk(CZ) LC06010 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z60870520 Keywords : beta-N-Acetylhexosaminidase * computer modelling * modified substrate Subject RIV: CE - Biochemistry Impact factor: 2.406, year: 2011

  11. Modified bag models for the quark–gluon plasma equation of state

    International Nuclear Information System (INIS)

    Begun, V.V.; Gorenstein, M.I.; Mogilevsky, O.A.

    2011-01-01

    The modified versions of the bag model equation of state (EoS) are considered. They are constructed to satisfy the main qualitative features observed for the quark–gluon plasma EoS in the lattice QCD calculations. A quantitative comparison with the lattice results at high temperatures T are done in the SU(3) gluodynamics and in the full QCD with dynamical quarks. Our analysis advocates a negative value of the bag constant B. (author)

  12. Color Mixing Correction for Post-printed Patterns on Colored Background Using Modified Particle Density Model

    OpenAIRE

    Suwa , Misako; Fujimoto , Katsuhito

    2006-01-01

    http://www.suvisoft.com; Color mixing occurs between background and foreground colors when a pattern is post-printed on a colored area because ink is not completely opaque. This paper proposes a new method for the correction of color mixing in line pattern such as characters and stamps, by using a modified particle density model. Parameters of the color correction can be calculated from two sets of foreground and background colors. By employing this method, the colors of foreground patterns o...

  13. A Modified Cellular Automaton Approach for Mixed Bicycle Traffic Flow Modeling

    Directory of Open Access Journals (Sweden)

    Xiaonian Shan

    2015-01-01

    Full Text Available Several previous studies have used the Cellular Automaton (CA for the modeling of bicycle traffic flow. However, previous CA models have several limitations, resulting in differences between the simulated and the observed traffic flow features. The primary objective of this study is to propose a modified CA model for simulating the characteristics of mixed bicycle traffic flow. Field data were collected on physically separated bicycle path in Shanghai, China, and were used to calibrate the CA model using the genetic algorithm. Traffic flow features between simulations of several CA models and field observations were compared. The results showed that our modified CA model produced more accurate simulation for the fundamental diagram and the passing events in mixed bicycle traffic flow. Based on our model, the bicycle traffic flow features, including the fundamental diagram, the number of passing events, and the number of lane changes, were analyzed. We also analyzed the traffic flow features with different traffic densities, traffic components on different travel lanes. Results of the study can provide important information for understanding and simulating the operations of mixed bicycle traffic flow.

  14. Modified Ammonia Removal Model Based on Equilibrium and Mass Transfer Principles

    International Nuclear Information System (INIS)

    Shanableh, A.; Imteaz, M.

    2010-01-01

    Yoon et al. 1 presented an approximate mathematical model to describe ammonia removal from an experimental batch reactor system with gaseous headspace. The development of the model was initially based on assuming instantaneous equilibrium between ammonia in the aqueous and gas phases. In the model, a 'saturation factor, β' was defined as a constant and used to check whether the equilibrium assumption was appropriate. The authors used the trends established by the estimated β values to conclude that the equilibrium assumption was not valid. The authors presented valuable experimental results obtained using a carefully designed system and the model used to analyze the results accounted for the following effects: speciation of ammonia between NH 3 and NH 4 + as a function of pH: temperature dependence of the reactions constants; and air flow rate. In this article, an alternative model based on the exact solution of the governing mass-balance differential equations was developed and used to describe ammonia removal without relying on the use of the saturation factor. The modified model was also extended to mathematically describe the pH dependence of the ammonia removal rate, in addition to accounting for the speciation of ammonia, temperature dependence of reactions constants, and air flow rate. The modified model was used to extend the analysis of the original experimental data presented by Yoon et al. 1 and the results matched the theory in an excellent manner

  15. A Discrete Numerical Scheme of Modified Leslie-Gower With Harvesting Model

    Directory of Open Access Journals (Sweden)

    Riski Nur Istiqomah Dinnullah

    2018-05-01

    Full Text Available Recently, exploitation of biological resources and the harvesting of two populations or more are widely practiced, such as fishery or foresty. The simplest way to describe the interaction of two species is by using predator prey model, that is one species feeds on another. The Leslie-Gower predator prey model has been studied in many works. In this paper, we use Euler method to discretisize the modified Leslie-Gower with harvesting model. The model consists of two simultanious predator prey equations. We show numerically that this discrete numerical scheme model is dynamically consistent with its continuous model only for relatively small step-size. By using computer simulation software, we show that equlibrium points can be stable, saddles, and unstable. It is shown that the numerical simulations not only illustrate the results, but also show the rich dynamics behaviors of the discrete system.

  16. Unifying dark energy and dark matter with the modified Ricci model

    International Nuclear Information System (INIS)

    Zhang, Linsen; Wu, Puxun; Yu, Hongwei

    2011-01-01

    In this paper, two modified Ricci models are considered as the candidates of unified dark matter-dark energy. In model one, the energy density is given by ρ MR =3M pl (αH 2 + βH), whereas, in model two, by ρ MR =3M pl ((α)/(6)R + γH H -1 ). We find that they can explain both dark matter and dark energy successfully. A constant equation of state of dark energy is obtained in model one, which means that it gives the same background evolution as the wCDM model, while model two can give an evolutionary equation of state of dark energy with the phantom divide line crossing in the near past. (orig.)

  17. Investigation of the liquid crystalline phase transitions using the new modified Pople Karasz model

    Science.gov (United States)

    Yazıcı, Mustafa; Özgan, Şükrü; Keskin, Mustafa

    2005-09-01

    Thermodynamics of solid nematic and nematic isotropic liquid transitions are studied by using a new modified model that combines the modified theories of Chandrasekhar et al. with those Keskin and Özgan which are based on the Pople Karasz theory. The thermodynamic properties of the disordered system are evaluated relative to those of the perfectly ordered one within the lowest approximation of the cluster variation method which is identical to the mean-field approximation. The results are compared with the some available experimental data, the predictions of the original Pople Karasz (PK) theory and its previous modified theories. For nematic isotropic and s(nematic) at the transition temperatures, the agreement is very good and much better than the predictions of the PK theory and its previous modified theories. For the solid nematic transition, all theories give very nearly the same results, but the values are significantly lower than the observed data. Moreover, one of the theoretical phase diagrams is also qualitatively similar to the experimental phase diagram for p-azoxyphenetole (PAA).

  18. Investigation of the liquid crystalline phase transitions using the new modified Pople-Karasz model

    International Nuclear Information System (INIS)

    Yazici, Mustafa; Oezgan, Suekrue; Keskin, Mustafa

    2005-01-01

    Thermodynamics of solid-nematic and nematic-isotropic liquid transitions are studied by using a new modified model that combines the modified theories of Chandrasekhar et al. with those Keskin and Oezgan which are based on the Pople-Karasz theory. The thermodynamic properties of the disordered system are evaluated relative to those of the perfectly ordered one within the lowest approximation of the cluster variation method which is identical to the mean-field approximation. The results are compared with the some available experimental data, the predictions of the original Pople-Karasz (PK) theory and its previous modified theories. For nematic-isotropic and s(nematic) at the transition temperatures, the agreement is very good and much better than the predictions of the PK theory and its previous modified theories. For the solid-nematic transition, all theories give very nearly the same results, but the values are significantly lower than the observed data. Moreover, one of the theoretical phase diagrams is also qualitatively similar to the experimental phase diagram for p-azoxyphenetole (PAA)

  19. Training of Students’ Critical Thinking Skills through the implementation of a Modified Free Inquiry Model

    Science.gov (United States)

    Hadi, S. A.; Susantini, E.; Agustini, R.

    2018-01-01

    This research aimed at training students’ critical thinking skills through the implementation of a modified free inquiry learning model. The subjects of this research were 21 students of Mathematics Semester II. Using One-Group Pretest-Posttest Design, the data were analyzed descriptively using N-gain indicator. The results indicate that the modified free inquiry learning model was effective to train students’ critical thinking skills. The increase in the students’ critical thinking skills viewed from the value of N-Gain has a range of values with the categories of medium and high with a score between 0,25-0,95. Overall, the change in N-Gain score of each student and each indicator of critical thinking skills is as increasing with a moderate category. The increase of N-Gain value is resulted from the fact that the students were directly involved in organizing their learning process. These criteria indicate that the modified free inquiry learning model can be used to train students’ critical thinking skills on photosynthesis and cellular respiration materials. The results of this research are expected to be nationally implemented to familiarize students with andragogy learning style which places the students as the subjects of learning.

  20. Two modified versions of the speciation code PHREEQE for modelling macromolecule-proton/cation interaction

    International Nuclear Information System (INIS)

    Falck, W.E.

    1991-01-01

    There is a growing need to consider the influence of organic macromolecules on the speciation of ions in natural waters. It is recognized that a simple discrete ligand approach to the binding of protons/cations to organic macromolecules is not appropriate to represent heterogeneities of binding site distributions. A more realistic approach has been incorporated into the speciation code PHREEQE which retains the discrete ligand approach but modifies the binding intensities using an electrostatic (surface complexation) model. To allow for different conformations of natural organic material two alternative concepts have been incorporated: it is assumed that (a) the organic molecules form rigid, impenetrable spheres, and (b) the organic molecules form flat surfaces. The former concept will be more appropriate for molecules in the smaller size range, while the latter will be more representative for larger size molecules or organic surface coatings. The theoretical concept is discussed and the relevant changes to the standard PHREEQE code are explained. The modified codes are called PHREEQEO-RS and PHREEQEO-FS for the rigid-sphere and flat-surface models respectively. Improved output facilities for data transfer to other computers, e.g. the Macintosh, are introduced. Examples where the model is tested against literature data are shown and practical problems are discussed. Appendices contain listings of the modified subroutines GAMMA and PTOT, an example input file and an example command procedure to run the codes on VAX computers

  1. Improved simulation of precipitation in the tropics using a modified BMJ scheme in the WRF model

    Science.gov (United States)

    Fonseca, R. M.; Zhang, T.; Yong, K.-T.

    2015-09-01

    The successful modelling of the observed precipitation, a very important variable for a wide range of climate applications, continues to be one of the major challenges that climate scientists face today. When the Weather Research and Forecasting (WRF) model is used to dynamically downscale the Climate Forecast System Reanalysis (CFSR) over the Indo-Pacific region, with analysis (grid-point) nudging, it is found that the cumulus scheme used, Betts-Miller-Janjić (BMJ), produces excessive rainfall suggesting that it has to be modified for this region. Experimentation has shown that the cumulus precipitation is not very sensitive to changes in the cloud efficiency but varies greatly in response to modifications of the temperature and humidity reference profiles. A new version of the scheme, denoted "modified BMJ" scheme, where the humidity reference profile is more moist, was developed. In tropical belt simulations it was found to give a better estimate of the observed precipitation as given by the Tropical Rainfall Measuring Mission (TRMM) 3B42 data set than the default BMJ scheme for the whole tropics and both monsoon seasons. In fact, in some regions the model even outperforms CFSR. The advantage of modifying the BMJ scheme to produce better rainfall estimates lies in the final dynamical consistency of the rainfall with other dynamical and thermodynamical variables of the atmosphere.

  2. Modeling of Photovoltaic System with Modified Incremental Conductance Algorithm for Fast Changes of Irradiance

    Directory of Open Access Journals (Sweden)

    Saad Motahhir

    2018-01-01

    Full Text Available The first objective of this work is to determine some of the performance parameters characterizing the behavior of a particular photovoltaic (PV panels that are not normally provided in the manufacturers’ specifications. These provide the basis for developing a simple model for the electrical behavior of the PV panel. Next, using this model, the effects of varying solar irradiation, temperature, series and shunt resistances, and partial shading on the output of the PV panel are presented. In addition, the PV panel model is used to configure a large photovoltaic array. Next, a boost converter for the PV panel is designed. This converter is put between the panel and the load in order to control it by means of a maximum power point tracking (MPPT controller. The MPPT used is based on incremental conductance (INC, and it is demonstrated here that this technique does not respond accurately when solar irradiation is increased. To investigate this, a modified incremental conductance technique is presented in this paper. It is shown that this system does respond accurately and reduces the steady-state oscillations when solar irradiation is increased. Finally, simulations of the conventional and modified algorithm are compared, and the results show that the modified algorithm provides an accurate response to a sudden increase in solar irradiation.

  3. Modified finite element transport model, FETRA, for sediment and radionuclide migration in open coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Mayer, D.W.

    1979-08-01

    The finite element model, FETRA, simulates transport of sediment and radionuclides (and other contaminants, such as heavy metals, pesticides, and other toxic substances) in surface water bodies. The model is an unsteady, two-dimensional (longitudinal and lateral) model which consists of the following three submodels coupled to include sediment-contaminant interactions: (1) sediment transport submodel, (2) dissolved contaminant transport submodel, and (3) particulate contaminant (contaminant adsorbed by sediment) transport submodel. Under the current phase of the study, FETRA was modified to include sediment-wave interaction in order to extend the applicability of the model to coastal zones and large lakes (e.g., the Great Lakes) where wave actions can be one of the dominant mechanisms to transport sediment and toxic contaminant. FETRA was further modified to handle both linear and quadratic approximations to velocity and depth distributions in order to be compatible with various finite element hydrodynamic models (e.g., RMA II and CAFE) which supply hydrodynamic input data to FETRA. The next step is to apply FETRA to coastal zones to simulate transport of sediment and radionuclides with their interactions in order to test and verify the model under marine and large lacustrine environments

  4. Assessment of groundwater vulnerability by applying the modified DRASTIC model in Beihai City, China.

    Science.gov (United States)

    Wu, Xiaoyu; Li, Bin; Ma, Chuanming

    2018-05-01

    This study assesses vulnerability of groundwater to pollution in Beihai City, China, as a support of groundwater resource protection. The assessment result not only objectively reflects potential possibility of groundwater to contamination but also provides scientific basis for the planning and utilization of groundwater resources. This study optimizes the parameters consisting of natural factors and human factors upon the DRASTIC model and modifies the ratings of these parameters, based on the local environmental conditions for the study area. And a weight of each parameter is assigned by the analytic hierarchy process (AHP) to reduce the subjectivity of humans to vulnerability assessment. The resulting scientific ratings and weights of modified DRASTIC model (AHP-DRASTLE model) contribute to obtain the more realistic assessment of vulnerability of groundwater to contaminant. The comparison analysis validates the accuracy and rationality of the AHP-DRASTLE model and shows it suits the particularity of the study area. The new assessment method (AHP-DRASTLE model) can provide a guide for other scholars to assess the vulnerability of groundwater to contamination. The final vulnerability map for the AHP-DRASTLE model shows four classes: highest (2%), high (29%), low (55%), and lowest (14%). The vulnerability map serves as a guide for decision makers on groundwater resource protection and land use planning at the regional scale and that it is adapted to a specific area.

  5. INFLUENCE OF MODIFIED BIOFLAVONOIDS UPON EFFECTOR LYMPHOCYTES IN MURINE MODEL OF CONTACT SENSITIVITY

    Directory of Open Access Journals (Sweden)

    D. Z. Albegova

    2015-01-01

    Full Text Available Contact sensitivity reaction (CSR to 2,4-dinitrofluorobenzene (DNFB in mice is a model of in vivo immune response, being an experimental analogue to contact dermatitis in humans. CSR sensitization phase begins after primary contact with antigen, lasting for 10-15 days in humans, and 5-7 days, in mice. Repeated skin exposure to the sensitizing substance leads to its recognition and triggering immune inflammatory mechanisms involving DNFB-specific effector T lymphocytes. The CSR reaches its maximum 18-48 hours after re-exposure to a hapten. There is only scarce information in the literature about effects of flavonoids on CSR, including both stimulatory and inhibitory effects. Flavonoids possessed, predominantly, suppressive effects against the CSR development. In our laboratory, a model of contact sensitivity was reproduced in CBA mice by means of cutaneous sensitization by 2,4-dinitrofluorobenzene. The aim of the study was to identify the mechanisms of immunomodulatory action of quercetin dihydrate and modified bioflavonoids, using the method of adoptive transfer contact sensitivity by splenocytes and T-lymphocytes. As shown in our studies, a 30-min pre-treatment of splenocytes and T-lymphocytes from sensitized mice with modified bioflavonoids before the cell transfer caused complete prevention of contact sensitivity reaction in syngeneic recipient mice. Meanwhile, this effect was not associated with cell death induction due to apoptosis or cytotoxicity. Quercetin dihydrate caused only partially suppression the activity of adaptively formed T-lymphocytes, the contact sensitivity effectors. It was shown that the modified bioflavonoid more stronger suppress adoptive transfer of contact sensitivity in comparison with quercetin dehydrate, without inducing apoptosis of effector cells. Thus, the modified bioflavonoid is a promising compound for further studies in a model of contact sensitivity, due to its higher ability to suppress transfer of CSR with

  6. Comparison of microfacet BRDF model to modified Beckmann-Kirchhoff BRDF model for rough and smooth surfaces.

    Science.gov (United States)

    Butler, Samuel D; Nauyoks, Stephen E; Marciniak, Michael A

    2015-11-02

    A popular class of BRDF models is the microfacet models, where geometric optics is assumed. In contrast, more complex physical optics models may more accurately predict the BRDF, but the calculation is more resource intensive. These seemingly disparate approaches are compared in detail for the rough and smooth surface approximations of the modified Beckmann-Kirchhoff BRDF model, assuming Gaussian surface statistics. An approximation relating standard Fresnel reflection with the semi-rough surface polarization term, Q, is presented for unpolarized light. For rough surfaces, the angular dependence of direction cosine space is shown to be identical to the angular dependence in the microfacet distribution function. For polished surfaces, the same comparison shows a breakdown in the microfacet models. Similarities and differences between microfacet BRDF models and the modified Beckmann-Kirchhoff model are identified. The rationale for the original Beckmann-Kirchhoff F(bk)(2) geometric term relative to both microfacet models and generalized Harvey-Shack model is presented. A modification to the geometric F(bk)(2) term in original Beckmann-Kirchhoff BRDF theory is proposed.

  7. Study on isotopic distribution produced by nucleus-nucleus collisions with modified SAA model

    International Nuclear Information System (INIS)

    Zhong Chen; Fang Deqing; Cai Xiangzhou; Shen Wenqing; Zhang Huyong; Wei Yibin; Ma Yugang

    2003-01-01

    Base on Brohm's Statistic-Ablation-Abrasion (SAA) model, the modified SAA model was developed via introducing the isospin dependence of nucleon distribution in nucleus and parameterized formulas for nucleon-nucleon cross section in nuclear matter. It can simulate well the isotopic distribution at both high and intermediate energies. By the improvement of computational method, the range of calculation of isotopic distribution can be increased from three order magnitude to eight order magnitude (even higher). It can reproduce experimental data and predict the isotopic distribution for very far from stability line which is very important from experimental viewpoint

  8. Self-modified quasi-stationary model for the radiation ablation

    International Nuclear Information System (INIS)

    Zhang Jun; Pei Wenbing; Gu Peijun; Sui Chengzhi; Chang Tieqiang

    1996-01-01

    The self-modified quasi-stationary model for radiation ablation has been established based on physical picture of numerical simulations. The objective of the model is to predict quantitatively the scaling laws of various ablation parameters driven by soft-X-ray, such as the dependence of ablation depth, pressure on radiation temperature, energy, pulse width, without resorting to complex computer simulations. The computational results are given for some interesting materials in ICF. Scaling laws obtained are simple and effective in target design and analysis of experimental results

  9. Determination of Burst Pressure of API Steel Pipes using Stress Modified Critical Strain Model

    International Nuclear Information System (INIS)

    Alang, N A; Razak, N A; Sulaiman, A S

    2012-01-01

    This paper presents a technique which can be used to determine the burst pressure of defective steel pipes using non-linear finite element (FE) analysis. The technique uses stress modified critical strain (SMCS) failure criterion to study the effect of gouge defects on maximum working pressure of API X65 steel pipes. The procedures in determining the model parameters using 3-D, homogeneous isotropic elastic-plastic material model with large deformation finite element analyses from notched tensile bars were systematically discussed. The relationship between burst pressure and gouge depth was proposed. The burst pressure estimated then was compared to experimental data from the literature for validation showing overall good agreements.

  10. Levitation force on a permanent magnet over a superconducting plane: Modified critical-state model

    International Nuclear Information System (INIS)

    Yang, Z.J.

    1997-01-01

    The authors consider a model system of a permanent magnet above a semi-infinite superconductor. They introduce a modified critical-state model, and carry out derivations of the levitation force acting on the magnet. A key feature of the modification allows the current density to be less than the critical value. The theoretical results show an exponential relationship between the force and the distance. Analytical expressions are developed for permanent magnets in the form of a point dipole, a tip of a magnetic force microscope, and a cylindrical magnet. In the latter case, the exponential relationship has been observed in numerous experiments but without previous interpretation

  11. A Modified Groundwater Flow Model Using the Space Time Riemann-Liouville Fractional Derivatives Approximation

    Directory of Open Access Journals (Sweden)

    Abdon Atangana

    2014-01-01

    Full Text Available The notion of uncertainty in groundwater hydrology is of great importance as it is known to result in misleading output when neglected or not properly accounted for. In this paper we examine this effect in groundwater flow models. To achieve this, we first introduce the uncertainties functions u as function of time and space. The function u accounts for the lack of knowledge or variability of the geological formations in which flow occur (aquifer in time and space. We next make use of Riemann-Liouville fractional derivatives that were introduced by Kobelev and Romano in 2000 and its approximation to modify the standard version of groundwater flow equation. Some properties of the modified Riemann-Liouville fractional derivative approximation are presented. The classical model for groundwater flow, in the case of density-independent flow in a uniform homogeneous aquifer is reformulated by replacing the classical derivative by the Riemann-Liouville fractional derivatives approximations. The modified equation is solved via the technique of green function and the variational iteration method.

  12. Modified pressure loss model for T-junctions of engine exhaust manifold

    Science.gov (United States)

    Wang, Wenhui; Lu, Xiaolu; Cui, Yi; Deng, Kangyao

    2014-11-01

    The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.

  13. Measurement and Modeling of Respiration Rate of Tomato (Cultivar Roma) for Modified Atmosphere Storage.

    Science.gov (United States)

    Kandasamy, Palani; Moitra, Ranabir; Mukherjee, Souti

    2015-01-01

    Experiments were conducted to determine the respiration rate of tomato at 10, 20 and 30 °C using closed respiration system. Oxygen depletion and carbon dioxide accumulation in the system containing tomato was monitored. Respiration rate was found to decrease with increasing CO2 and decreasing O2 concentration. Michaelis-Menten type model based on enzyme kinetics was evaluated using experimental data generated for predicting the respiration rate. The model parameters that obtained from the respiration rate at different O2 and CO2 concentration levels were used to fit the model against the storage temperatures. The fitting was fair (R2 = 0.923 to 0.970) when the respiration rate was expressed as O2 concentation. Since inhibition constant for CO2 concentration tended towards negetive, the model was modified as a function of O2 concentration only. The modified model was fitted to the experimental data and showed good agreement (R2 = 0.998) with experimentally estimated respiration rate.

  14. The Use of Indicators in Modified Historical Model to Estimate the Intrinsic Value of a Stock

    Directory of Open Access Journals (Sweden)

    Gottwald Radim

    2012-06-01

    Full Text Available The article mentions several methods of a fundamental analysis used to value stocks. It primarily focuses on the historical model. This model enables undervalued, correctly valued and overvalued stocks to be identified. The model is further modified in the article, using selected accounting indicators. The modified model versions are applied to selected stocks in the SPAD segment, Prague Stock Exchange, within the 2005-2010 period. Empirical analysis is applied to a comparison of accuracy of the accounting indicator value estimates and accuracy of stock intrinsic value estimates, both separately for each stock and accounting indicator. The comparisons of accuracy of the accounting indicator value estimates and the accuracy of the stock intrinsic value estimates are also done based on the length of applied time period. With respect to the obvious fierce competition between stock issuers within the financial markets, the model enables potential investors, who are to select from an extensive offer of stocks, to make better informed investment decisions.

  15. On-line core monitoring system based on buckling corrected modified one group model

    International Nuclear Information System (INIS)

    Freire, Fernando S.

    2011-01-01

    Nuclear power reactors require core monitoring during plant operation. To provide safe, clean and reliable core continuously evaluate core conditions. Currently, the reactor core monitoring process is carried out by nuclear code systems that together with data from plant instrumentation, such as, thermocouples, ex-core detectors and fixed or moveable In-core detectors, can easily predict and monitor a variety of plant conditions. Typically, the standard nodal methods can be found on the heart of such nuclear monitoring code systems. However, standard nodal methods require large computer running times when compared with standards course-mesh finite difference schemes. Unfortunately, classic finite-difference models require a fine mesh reactor core representation. To override this unlikely model characteristic we can usually use the classic modified one group model to take some account for the main core neutronic behavior. In this model a course-mesh core representation can be easily evaluated with a crude treatment of thermal neutrons leakage. In this work, an improvement made on classic modified one group model based on a buckling thermal correction was used to obtain a fast, accurate and reliable core monitoring system methodology for future applications, providing a powerful tool for core monitoring process. (author)

  16. Class B Gene Expression and the Modified ABC Model in Nongrass Monocots

    Directory of Open Access Journals (Sweden)

    Akira Kanno

    2007-01-01

    Full Text Available The discovery of the MADS-box genes and the study of model plants such as Arabidopsis thaliana and Antirrhinum majus have greatly improved our understanding of the molecular mechanisms driving the diversity in floral development. The class B genes, which belong to the MADS-box gene family, are important regulators of the development of petals and stamens in flowering plants. Many nongrass monocot flowers have two whorls of petaloid organs, which are called tepals. To explain this floral morphology, the modified ABC model was proposed. This model was exemplified by the tulip, in which expansion and restriction of class B gene expression is linked to the transition of floral morphologies in whorl 1. The expression patterns of class B genes from many monocot species nicely fit this model; however, those from some species, such as asparagus, do not. In this review, we summarize the relationship between class B gene expression and floral morphology in nongrass monocots, such as Liliales (Liliaceae and Asparagales species, and discuss the applicability of the modified ABC model to monocot flowers.

  17. Modelling of the modified-LLCL-filter-based single-phase grid-tied Aalborg inverter

    DEFF Research Database (Denmark)

    Liu, Zifa; Wu, Huiyun; Liu, Yuan

    2017-01-01

    Owing to less conduction and switching power losses, the recently proposed Aalborg inverter has high efficiency within a wide range of input DC voltage for single-phase DC/AC power conversion. In theory, the conduction power losses can be further decreased, if an LLCL-filter is adopted instead...... of an LCL-filter for a voltage source inverter, mainly due to the reduced inductance. The Aalborg inverter shows the characteristic of a current source inverter, when working in the `boost' state. Whether the LLCL-filter can meet the control requirement of this type inverter needs to be further explored....... In this study, the small signal analysis for the modified-LLCL-filter-based Aalborg inverter is addressed. Through the modelling, it can be proven that compared with the LCL-filter, the modified-LLCL-filter causes no extra control challenge for the Aalborg inverter, and therefore more inductance in the power...

  18. The modified SWAT model for predicting fecal coliforms in the Wachusett Reservoir Watershed, USA.

    Science.gov (United States)

    Cho, Kyung Hwa; Pachepsky, Yakov A; Kim, Joon Ha; Kim, Jung-Woo; Park, Mi-Hyun

    2012-10-01

    This study assessed fecal coliform contamination in the Wachusett Reservoir Watershed in Massachusetts, USA using Soil and Water Assessment Tool (SWAT) because bacteria are one of the major water quality parameters of concern. The bacteria subroutine in SWAT, considering in-stream bacteria die-off only, was modified in this study to include solar radiation-associated die-off and the contribution of wildlife. The result of sensitivity analysis demonstrates that solar radiation is one of the most significant fate factors of fecal coliform. A water temperature-associated function to represent the contribution of beaver activity in the watershed to fecal contamination improved prediction accuracy. The modified SWAT model provides an improved estimate of bacteria from the watershed. Our approach will be useful for simulating bacterial concentrations to provide predictive and reliable information of fecal contamination thus facilitating the implementation of effective watershed management. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Modifying Geometric-Optical Bidirectional Reflectance Model for Direct Inversion of Forest Canopy Leaf Area Index

    Directory of Open Access Journals (Sweden)

    Congrong Li

    2015-08-01

    Full Text Available Forest canopy leaf area index (LAI inversion based on remote sensing data is an important method to obtain LAI. Currently, the most widely-used model to achieve forest canopy structure parameters is the Li-Strahler geometric-optical bidirectional reflectance model, by considering the effect of crown shape and mutual shadowing, which is referred to as the GOMS model. However, it is difficult to retrieve LAI through the GOMS model directly because LAI is not a fundamental parameter of the model. In this study, a gap probability model was used to obtain the relationship between the canopy structure parameter nR2 and LAI. Thus, LAI was introduced into the GOMS model as an independent variable by replacing nR2 The modified GOMS (MGOMS model was validated by application to Dayekou in the Heihe River Basin of China. The LAI retrieved using the MGOMS model with optical multi-angle remote sensing data, high spatial resolution images and field-measured data was in good agreement with the field-measured LAI, with an R-square (R2 of 0.64, and an RMSE of 0.67. The results demonstrate that the MGOMS model obtained by replacing the canopy structure parameter nR2 of the GOMS model with LAI can be used to invert LAI directly and precisely.

  20. Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balances

    Science.gov (United States)

    Tang, G.; Bartlein, P. J.

    2012-08-01

    Satellite-based data, such as vegetation type and fractional vegetation cover, are widely used in hydrologic models to prescribe the vegetation state in a study region. Dynamic global vegetation models (DGVM) simulate land surface hydrology. Incorporation of satellite-based data into a DGVM may enhance a model's ability to simulate land surface hydrology by reducing the task of model parameterization and providing distributed information on land characteristics. The objectives of this study are to (i) modify a DGVM for simulating land surface water balances; (ii) evaluate the modified model in simulating actual evapotranspiration (ET), soil moisture, and surface runoff at regional or watershed scales; and (iii) gain insight into the ability of both the original and modified model to simulate large spatial scale land surface hydrology. To achieve these objectives, we introduce the "LPJ-hydrology" (LH) model which incorporates satellite-based data into the Lund-Potsdam-Jena (LPJ) DGVM. To evaluate the model we ran LH using historical (1981-2006) climate data and satellite-based land covers at 2.5 arc-min grid cells for the conterminous US and for the entire world using coarser climate and land cover data. We evaluated the simulated ET, soil moisture, and surface runoff using a set of observed or simulated data at different spatial scales. Our results demonstrate that spatial patterns of LH-simulated annual ET and surface runoff are in accordance with previously published data for the US; LH-modeled monthly stream flow for 12 major rivers in the US was consistent with observed values respectively during the years 1981-2006 (R2 > 0.46, p 0.52). The modeled mean annual discharges for 10 major rivers worldwide also agreed well (differences day method for snowmelt computation, the addition of the solar radiation effect on snowmelt enabled LH to better simulate monthly stream flow in winter and early spring for rivers located at mid-to-high latitudes. In addition, LH-modeled

  1. An Optimization Model and Modified Harmony Search Algorithm for Microgrid Planning with ESS

    Directory of Open Access Journals (Sweden)

    Yang Jiao

    2017-01-01

    Full Text Available To solve problems such as the high cost of microgrids (MGs, balance between supply and demand, stability of system operation, and optimizing the MG planning model, the energy storage system (ESS and harmony search algorithm (HSA are proposed. First, the conventional MG planning optimization model is constructed and the constraint conditions are defined: the supply and demand balance and reserve requirements. Second, an ESS is integrated into the optimal model of MG planning. The model with an ESS can solve and identify parameters such as the optimal power, optimal capacity, and optimal installation year. Third, the convergence speed and robustness of the ESS are optimized and improved. A case study comprising three different cases concludes the paper. The results show that the modified HSA (MHSA can effectively improve the stability and economy of MG operation with an ESS.

  2. Prediction of the fuel failure following a large LOCA using modified gap heat transfer model

    International Nuclear Information System (INIS)

    Lee, K.M.; Lee, N.H.; Huh, J.Y.; Seo, S.K.; Choi, J.H.

    1995-01-01

    The modified Ross and Stoute gap heat transfer model in the ELOCA.Mk5 code for CANDU safety analysis is based on a simplified thermal deformation model. A review on a series of recent experiments reveals that fuel pellets crack, relocate, and are eccentrically positioned within the sheath rather than solid concentric cylinders. In this study, more realistic offset crap conductance model is implemented in the code to estimate the fuel failure thresholds usincr the transient conditions of a 100% Reactor Outlet Header (ROH) break LOCA. Based on the offset gap conductance model, the total release of I-131 from the failed fuel elements in the core is reduced from 3876 TBq to 3283 TBq to increase margin for dose limit. (author)

  3. A combined model based on CEEMDAN and modified flower pollination algorithm for wind speed forecasting

    International Nuclear Information System (INIS)

    Zhang, Wenyu; Qu, Zongxi; Zhang, Kequan; Mao, Wenqian; Ma, Yining; Fan, Xu

    2017-01-01

    Highlights: • A CEEMDAN-CLSFPA combined model is proposed for short-term wind speed forecasting. • The CEEMDAN technique is used to decompose the original wind speed series. • A modified optimization algorithm-CLSFPA is proposed to optimize the weights of the combined model. • The no negative constraint theory is applied to the combined model. • Robustness of the proposed model is validated by data sampled from four different wind farms. - Abstract: Wind energy, which is stochastic and intermittent by nature, has a significant influence on power system operation, power grid security and market economics. Precise and reliable wind speed prediction is vital for wind farm planning and operational planning for power grids. To improve wind speed forecasting accuracy, a large number of forecasting approaches have been proposed; however, these models typically do not account for the importance of data preprocessing and are limited by the use of individual models. In this paper, a novel combined model – combining complete ensemble empirical mode decomposition adaptive noise (CEEMDAN), flower pollination algorithm with chaotic local search (CLSFPA), five neural networks and no negative constraint theory (NNCT) – is proposed for short-term wind speed forecasting. First, a recent CEEMDAN is employed to divide the original wind speed data into a finite set of IMF components, and then a combined model, based on NNCT, is proposed for forecasting each decomposition signal. To improve the forecasting capacity of the combined model, a modified flower pollination algorithm (FPA) with chaotic local search (CLS) is proposed and employed to determine the optimal weight coefficients of the combined model, and the final prediction values were obtained by reconstructing the refined series. To evaluate the forecasting ability of the proposed combined model, 15-min wind speed data from four wind farms in the eastern coastal areas of China are used. The experimental results of

  4. Channel Parameter Estimation for Scatter Cluster Model Using Modified MUSIC Algorithm

    Directory of Open Access Journals (Sweden)

    Jinsheng Yang

    2012-01-01

    Full Text Available Recently, the scatter cluster models which precisely evaluate the performance of the wireless communication system have been proposed in the literature. However, the conventional SAGE algorithm does not work for these scatter cluster-based models because it performs poorly when the transmit signals are highly correlated. In this paper, we estimate the time of arrival (TOA, the direction of arrival (DOA, and Doppler frequency for scatter cluster model by the modified multiple signal classification (MUSIC algorithm. Using the space-time characteristics of the multiray channel, the proposed algorithm combines the temporal filtering techniques and the spatial smoothing techniques to isolate and estimate the incoming rays. The simulation results indicated that the proposed algorithm has lower complexity and is less time-consuming in the dense multipath environment than SAGE algorithm. Furthermore, the estimations’ performance increases with elements of receive array and samples length. Thus, the problem of the channel parameter estimation of the scatter cluster model can be effectively addressed with the proposed modified MUSIC algorithm.

  5. Evaluation of teledermatology adoption by health-care professionals using a modified Technology Acceptance Model.

    Science.gov (United States)

    Orruño, Estibalitz; Gagnon, Marie Pierre; Asua, José; Ben Abdeljelil, Anis

    2011-01-01

    We examined the main factors affecting the intention of physicians to use teledermatology using a modified Technology Acceptance Model (TAM). The investigation was carried out during a teledermatology pilot study conducted in Spain. A total of 276 questionnaires were sent to physicians by email and 171 responded (62%). Cronbach's alpha was acceptably high for all constructs. Theoretical variables were well correlated with each other and with the dependent variable (Intention to Use). Logistic regression indicated that the original TAM model was good at predicting physicians' intention to use teledermatology and that the variables Perceived Usefulness and Perceived Ease of Use were both significant (odds ratios of 8.4 and 7.4, respectively). When other theoretical variables were added, the model was still significant and it also became more powerful. However, the only significant predictor in the modified model was Facilitators with an odds ratio of 9.9. Thus the TAM was good at predicting physicians' intention to use teledermatology. However, the most important variable was the perception of Facilitators to using the technology (e.g. infrastructure, training and support).

  6. A modified dynamic evolving neural-fuzzy approach to modeling customer satisfaction for affective design.

    Science.gov (United States)

    Kwong, C K; Fung, K Y; Jiang, Huimin; Chan, K Y; Siu, Kin Wai Michael

    2013-01-01

    Affective design is an important aspect of product development to achieve a competitive edge in the marketplace. A neural-fuzzy network approach has been attempted recently to model customer satisfaction for affective design and it has been proved to be an effective one to deal with the fuzziness and non-linearity of the modeling as well as generate explicit customer satisfaction models. However, such an approach to modeling customer satisfaction has two limitations. First, it is not suitable for the modeling problems which involve a large number of inputs. Second, it cannot adapt to new data sets, given that its structure is fixed once it has been developed. In this paper, a modified dynamic evolving neural-fuzzy approach is proposed to address the above mentioned limitations. A case study on the affective design of mobile phones was conducted to illustrate the effectiveness of the proposed methodology. Validation tests were conducted and the test results indicated that: (1) the conventional Adaptive Neuro-Fuzzy Inference System (ANFIS) failed to run due to a large number of inputs; (2) the proposed dynamic neural-fuzzy model outperforms the subtractive clustering-based ANFIS model and fuzzy c-means clustering-based ANFIS model in terms of their modeling accuracy and computational effort.

  7. A Modified Dynamic Evolving Neural-Fuzzy Approach to Modeling Customer Satisfaction for Affective Design

    Directory of Open Access Journals (Sweden)

    C. K. Kwong

    2013-01-01

    Full Text Available Affective design is an important aspect of product development to achieve a competitive edge in the marketplace. A neural-fuzzy network approach has been attempted recently to model customer satisfaction for affective design and it has been proved to be an effective one to deal with the fuzziness and non-linearity of the modeling as well as generate explicit customer satisfaction models. However, such an approach to modeling customer satisfaction has two limitations. First, it is not suitable for the modeling problems which involve a large number of inputs. Second, it cannot adapt to new data sets, given that its structure is fixed once it has been developed. In this paper, a modified dynamic evolving neural-fuzzy approach is proposed to address the above mentioned limitations. A case study on the affective design of mobile phones was conducted to illustrate the effectiveness of the proposed methodology. Validation tests were conducted and the test results indicated that: (1 the conventional Adaptive Neuro-Fuzzy Inference System (ANFIS failed to run due to a large number of inputs; (2 the proposed dynamic neural-fuzzy model outperforms the subtractive clustering-based ANFIS model and fuzzy c-means clustering-based ANFIS model in terms of their modeling accuracy and computational effort.

  8. Evaluation of Meniscal Mechanics and Proteoglycan Content in a Modified Anterior Cruciate Ligament Transection Model

    Science.gov (United States)

    Fischenich, Kristine M.; Coatney, Garrett A.; Haverkamp, John H.; Button, Keith D.; DeCamp, Charlie; Haut, Roger C.; Haut Donahue, Tammy L.

    2014-01-01

    Post-traumatic osteoarthritis (PTOA) develops as a result of traumatic loading that causes tears of the soft tissues in the knee. A modified transection model, where the anterior cruciate ligament (ACL) and both menisci were transected, was used on skeletally mature Flemish Giant rabbits. Gross morphological assessments, elastic moduli, and glycosaminoglycan (GAG) coverage of the menisci were determined to quantify the amount of tissue damage 12 weeks post injury. This study is one of the first to monitor meniscal changes after inducing combined meniscal and ACL transections. A decrease in elastic moduli as well as a decrease in GAG coverage was seen. PMID:24749144

  9. About the Properties of a Modified Generalized Beverton-Holt Equation in Ecology Models

    OpenAIRE

    De La Sen, M.

    2008-01-01

    Es reproducción del documento publicado en http://dx.doi.org/10.1155/2008/592950 This paper is devoted to the study of a generalized modified version of the well-known Beverton-Holt equation in ecology. The proposed model describes the population evolution of some species in a certain habitat driven by six parametrical sequences, namely, the intrinsic growth rate (associated with the reproduction capability), the degree of sympathy of the species with the habitat (described by a so-called ...

  10. A modified Lotka-Volterra model for the evolution of coordinate symbiosis in energy enterprise

    Science.gov (United States)

    Zhou, Li; Wang, Teng; Lyu, Xiaohuan; Yu, Jing

    2018-02-01

    Recent developments in energy markets make the operating industries more dynamic and complex, and energy enterprises cooperate more closely in the industrial chain and symbiosis. In order to further discuss the evolution of coordinate symbiosis in energy enterprises, a modified Lotka-Volterra equation is introduced to develop a symbiosis analysis model of energy groups. According to the equilibrium and stability analysis, a conclusion is obtained that if the upstream energy group and the downstream energy group are in symbiotic state, the growth of their utility will be greater than their independent value. Energy enterprises can get mutual benefits and positive promotions in industrial chain by their cooperation.

  11. Thermodynamic aspect in using modified Boltzmann model as an acoustic probe for URu2Si2

    Science.gov (United States)

    Kwang-Hua, Chu Rainer

    2018-05-01

    The approximate system of equations describing ultrasonic attenuation propagating in many electrons of the heavy-fermion materials URu2Si2 under high magnetic fields were firstly derived and then calculated based on the modified Boltzmann model considering the microscopic contributions due to electronic fluids. A system of nonlinear partial differential coupled with integral equations were linearized firstly and approximately solved considering the perturbed thermodynamic equilibrium states. Our numerical data were compared with previous measurements using non-dimensional or normalized physical values. The rather good fit of our numerical calculations with experimental measurements confirms our present approach.

  12. Modified Chaos Particle Swarm Optimization-Based Optimized Operation Model for Stand-Alone CCHP Microgrid

    Directory of Open Access Journals (Sweden)

    Fei Wang

    2017-07-01

    Full Text Available The optimized dispatch of different distributed generations (DGs in stand-alone microgrid (MG is of great significance to the operation’s reliability and economy, especially for energy crisis and environmental pollution. Based on controllable load (CL and combined cooling-heating-power (CCHP model of micro-gas turbine (MT, a multi-objective optimization model with relevant constraints to optimize the generation cost, load cut compensation and environmental benefit is proposed in this paper. The MG studied in this paper consists of photovoltaic (PV, wind turbine (WT, fuel cell (FC, diesel engine (DE, MT and energy storage (ES. Four typical scenarios were designed according to different day types (work day or weekend and weather conditions (sunny or rainy in view of the uncertainty of renewable energy in variable situations and load fluctuation. A modified dispatch strategy for CCHP is presented to further improve the operation economy without reducing the consumers’ comfort feeling. Chaotic optimization and elite retention strategy are introduced into basic particle swarm optimization (PSO to propose modified chaos particle swarm optimization (MCPSO whose search capability and convergence speed are improved greatly. Simulation results validate the correctness of the proposed model and the effectiveness of MCPSO algorithm in the optimized operation application of stand-alone MG.

  13. Speeding up N -body simulations of modified gravity: chameleon screening models

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Sownak; Li, Baojiu; He, Jian-hua; Llinares, Claudio [Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Barreira, Alexandre [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Hellwing, Wojciech A.; Koyama, Kazuya [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Zhao, Gong-Bo, E-mail: sownak.bose@durham.ac.uk, E-mail: baojiu.li@durham.ac.uk, E-mail: barreira@mpa-garching.mpg.de, E-mail: jianhua.he@durham.ac.uk, E-mail: wojciech.hellwing@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk, E-mail: claudio.llinares@durham.ac.uk, E-mail: gbzhao@nao.cas.cn [National Astronomy Observatories, Chinese Academy of Science, Beijing, 100012 (China)

    2017-02-01

    We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied f ( R ) gravity models. High resolution simulations for such models are currently very slow due to the highly nonlinear partial differential equation that needs to be solved exactly to predict the modified gravitational force. This nonlinearity is partly inherent, but is also exacerbated by the specific numerical algorithm used, which employs a variable redefinition to prevent numerical instabilities. The standard Newton-Gauss-Seidel iterative method used to tackle this problem has a poor convergence rate. Our new method not only avoids this, but also allows the discretised equation to be written in a form that is analytically solvable. We show that this new method greatly improves the performance and efficiency of f ( R ) simulations. For example, a test simulation with 512{sup 3} particles in a box of size 512 Mpc/ h is now 5 times faster than before, while a Millennium-resolution simulation for f ( R ) gravity is estimated to be more than 20 times faster than with the old method. Our new implementation will be particularly useful for running very high resolution, large-sized simulations which, to date, are only possible for the standard model, and also makes it feasible to run large numbers of lower resolution simulations for covariance analyses. We hope that the method will bring us to a new era for precision cosmological tests of gravity.

  14. Speeding up N-body simulations of modified gravity: chameleon screening models

    Science.gov (United States)

    Bose, Sownak; Li, Baojiu; Barreira, Alexandre; He, Jian-hua; Hellwing, Wojciech A.; Koyama, Kazuya; Llinares, Claudio; Zhao, Gong-Bo

    2017-02-01

    We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied f(R) gravity models. High resolution simulations for such models are currently very slow due to the highly nonlinear partial differential equation that needs to be solved exactly to predict the modified gravitational force. This nonlinearity is partly inherent, but is also exacerbated by the specific numerical algorithm used, which employs a variable redefinition to prevent numerical instabilities. The standard Newton-Gauss-Seidel iterative method used to tackle this problem has a poor convergence rate. Our new method not only avoids this, but also allows the discretised equation to be written in a form that is analytically solvable. We show that this new method greatly improves the performance and efficiency of f(R) simulations. For example, a test simulation with 5123 particles in a box of size 512 Mpc/h is now 5 times faster than before, while a Millennium-resolution simulation for f(R) gravity is estimated to be more than 20 times faster than with the old method. Our new implementation will be particularly useful for running very high resolution, large-sized simulations which, to date, are only possible for the standard model, and also makes it feasible to run large numbers of lower resolution simulations for covariance analyses. We hope that the method will bring us to a new era for precision cosmological tests of gravity.

  15. Speeding up N -body simulations of modified gravity: chameleon screening models

    International Nuclear Information System (INIS)

    Bose, Sownak; Li, Baojiu; He, Jian-hua; Llinares, Claudio; Barreira, Alexandre; Hellwing, Wojciech A.; Koyama, Kazuya; Zhao, Gong-Bo

    2017-01-01

    We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied f ( R ) gravity models. High resolution simulations for such models are currently very slow due to the highly nonlinear partial differential equation that needs to be solved exactly to predict the modified gravitational force. This nonlinearity is partly inherent, but is also exacerbated by the specific numerical algorithm used, which employs a variable redefinition to prevent numerical instabilities. The standard Newton-Gauss-Seidel iterative method used to tackle this problem has a poor convergence rate. Our new method not only avoids this, but also allows the discretised equation to be written in a form that is analytically solvable. We show that this new method greatly improves the performance and efficiency of f ( R ) simulations. For example, a test simulation with 512 3 particles in a box of size 512 Mpc/ h is now 5 times faster than before, while a Millennium-resolution simulation for f ( R ) gravity is estimated to be more than 20 times faster than with the old method. Our new implementation will be particularly useful for running very high resolution, large-sized simulations which, to date, are only possible for the standard model, and also makes it feasible to run large numbers of lower resolution simulations for covariance analyses. We hope that the method will bring us to a new era for precision cosmological tests of gravity.

  16. About the Properties of a Modified Generalized Beverton-Holt Equation in Ecology Models

    Directory of Open Access Journals (Sweden)

    M. De La Sen

    2008-01-01

    Full Text Available This paper is devoted to the study of a generalized modified version of the well-known Beverton-Holt equation in ecology. The proposed model describes the population evolution of some species in a certain habitat driven by six parametrical sequences, namely, the intrinsic growth rate (associated with the reproduction capability, the degree of sympathy of the species with the habitat (described by a so-called environment carrying capacity, a penalty term to deal with overpopulation levels, the harvesting (fishing or hunting regulatory quota, or related to use of pesticides when fighting damaging plagues, and the independent consumption which basically quantifies predation. The independent consumption is considered as a part of a more general additive disturbance which also potentially includes another extra additive disturbance term which might be attributed to net migration from or to the habitat or modeling measuring errors. Both potential contributions are included for generalization purposes in the proposed modified generalized Beverton-Holt equation. The properties of stability and boundedness of the solution sequences, equilibrium points of the stationary model, and the existence of oscillatory solution sequences are investigated. A numerical example for a population of aphids is investigated with the theoretical tools developed in the paper.

  17. Understanding gender differences in m-health adoption: a modified theory of reasoned action model.

    Science.gov (United States)

    Zhang, Xiaofei; Guo, Xitong; Lai, Kee-Hung; Guo, Feng; Li, Chenlei

    2014-01-01

    Mobile health (m-health) services are becoming increasingly popular in healthcare, but research on m-health adoption is rare. This study was designed to obtain a better understanding of m-health adoption intention. We conducted an empirical research of a 481-respondent sample consisting of 44.7% women and 55.3% men and developed a modified theory of reasoned action (TRA) model by incorporating the nonlinearities between attitude and subjective norms and the moderating effect of gender. The results indicate that, based on the study population in China: (1) facilitating conditions, attitude, and subjective norms are significant predictors of m-health adoption intention; (2) the model including the nonlinearities enhances its explanatory ability; (3) males enjoy a higher level of m-health adoption intention compared with females; (4) the modified TRA model can predict men's behavior intention better than that of women; and (5) males have an Edgeworth-Pareto substitutability between attitude and subjective norms in predicting m-health adoption intention. Thus, we found gender differences in m-health adoption from the perspective of social psychology.

  18. METHODOLOGY FOR THE ESTIMATION OF PARAMETERS, OF THE MODIFIED BOUC-WEN MODEL

    Directory of Open Access Journals (Sweden)

    Tomasz HANISZEWSKI

    2015-03-01

    Full Text Available Bouc-Wen model is theoretical formulation that allows to reflect real hysteresis loop of modeled object. Such object is for example a wire rope, which is present on equipment of crane lifting mechanism. Where adopted modified version of the model has nine parameters. Determination of such a number of parameters is complex and problematic issue. In this article are shown the methodology to identify and sample results of numerical simulations. The results were compared with data obtained on the basis of laboratory tests of ropes [3] and on their basis it was found that there is compliance between results and there is possibility to apply in dynamic systems containing in their structures wire ropes [4].

  19. Creep simulation of adhesively bonded joints using modified generalized time hardening model

    Energy Technology Data Exchange (ETDEWEB)

    Sadigh, Mohammad Ali Saeimi [Azarbaijan Shahid Madani University, Tabriz (Iran, Islamic Republic of)

    2016-04-15

    Creep behavior of double lap adhesively bonded joints was investigated using experimental tests and numerical analysis. Firstly, uniaxial creep tests were carried out to obtain the creep characteristics and constitutive parameters of the adhesive at different stress and temperature levels. Generalized time hardening model was used to predict the creep behavior of the adhesive. This model was modified to simulate the creep behavior at different stress and temperature levels. Secondly, the developed model was used to simulate the creep behavior of bonded joints using finite element based numerical analysis. Creep deformations of the joints were measured experimentally and good agreement was observed in comparison with the results obtained using numerical simulation. Afterward, stress redistribution due to the creep along the adhesively bonded joint was obtained numerically. It was observed that temperature level had a significant effect on the stress redistribution along the adhesive thickness.

  20. Path Loss Prediction Over the Lunar Surface Utilizing a Modified Longley-Rice Irregular Terrain Model

    Science.gov (United States)

    Foore, Larry; Ida, Nathan

    2007-01-01

    This study introduces the use of a modified Longley-Rice irregular terrain model and digital elevation data representative of an analogue lunar site for the prediction of RF path loss over the lunar surface. The results are validated by theoretical models and past Apollo studies. The model is used to approximate the path loss deviation from theoretical attenuation over a reflecting sphere. Analysis of the simulation results provides statistics on the fade depths for frequencies of interest, and correspondingly a method for determining the maximum range of communications for various coverage confidence intervals. Communication system engineers and mission planners are provided a link margin and path loss policy for communication frequencies of interest.

  1. Modeling of fermentative hydrogen production from sweet sorghum extract based on modified ADM1

    DEFF Research Database (Denmark)

    Antonopoulou, Georgia; Gavala, Hariklia N.; Skiadas, Ioannis

    2012-01-01

    The Anaerobic digestion model 1 (ADM1) framework can be used to predict fermentative hydrogen production, since the latter is directly related to the acidogenic stage of the anaerobic digestion process. In this study, the ADM1 model framework was used to simulate and predict the process...... used for kinetic parameter validation. Since the ADM1 does not account for metabolic products such as lactic acid and ethanol that are crucial during the fermentative hydrogen production process, the structure of the model was modified to include lactate and ethanol among the metabolites and to improve...... of fermentative hydrogen production from the extractable sugars of sweet sorghum biomass. Kinetic parameters for sugars’ consumption and yield coefficients of acetic, propionic and butyric acid production were estimated using the experimental data obtained from the steady states of a CSTR. Batch experiments were...

  2. Multi-solid model modified to predict paraffin in petroleum fluids at high temperatures and pressures

    International Nuclear Information System (INIS)

    Escobar Remolina, Juan Carlos M; Barrios Ortiz, Wilson; Santoyo Ramirez Gildardo

    2009-01-01

    A thermodynamic structure has been modified in order to calculate cloud point, fluidity and amount of precipitated wax under a wide range of temperature conditions, composition, and high pressures. The model is based on a combination of ideal solution concepts, fluid characterization, and formation of multiple solid phases using Cubic State Equations. The experimental data utilized for testing the prediction capacity and potentiality of a model exhibit different characteristics: continuous series synthetic systems of heavy alkanes, discontinuous series, and dead or living petroleum fluids with indefinite fractions such as C7+, C10+, C20+, and C30+. The samples were taken from the literature, petroleum fluids from the main Colombian reservoirs, and some samples of Bolivian fluids. Results presented in this paper show the minimum standard deviations between experimental data and data calculated with a model. This allows a progress in decision-making processes for flow assurance in reservoirs, wells, and surface facilities in the petroleum industry.

  3. A radar-based hydrological model for flash flood prediction in the dry regions of Israel

    Science.gov (United States)

    Ronen, Alon; Peleg, Nadav; Morin, Efrat

    2014-05-01

    Flash floods are floods which follow shortly after rainfall events, and are among the most destructive natural disasters that strike people and infrastructures in humid and arid regions alike. Using a hydrological model for the prediction of flash floods in gauged and ungauged basins can help mitigate the risk and damage they cause. The sparsity of rain gauges in arid regions requires the use of radar measurements in order to get reliable quantitative precipitation estimations (QPE). While many hydrological models use radar data, only a handful do so in dry climate. This research presents a robust radar-based hydro-meteorological model built specifically for dry climate. Using this model we examine the governing factors of flash floods in the arid and semi-arid regions of Israel in particular and in dry regions in general. The hydrological model built is a semi-distributed, physically-based model, which represents the main hydrological processes in the area, namely infiltration, flow routing and transmission losses. Three infiltration functions were examined - Initial & Constant, SCS-CN and Green&Ampt. The parameters for each function were found by calibration based on 53 flood events in three catchments, and validation was performed using 55 flood events in six catchments. QPE were obtained from a C-band weather radar and adjusted using a weighted multiple regression method based on a rain gauge network. Antecedent moisture conditions were calculated using a daily recharge assessment model (DREAM). We found that the SCS-CN infiltration function performed better than the other two, with reasonable agreement between calculated and measured peak discharge. Effects of storm characteristics were studied using synthetic storms from a high resolution weather generator (HiReS-WG), and showed a strong correlation between storm speed, storm direction and rain depth over desert soils to flood volume and peak discharge.

  4. Thermodynamics of protein folding using a modified Wako-Saitô-Muñoz-Eaton model.

    Science.gov (United States)

    Tsai, Min-Yeh; Yuan, Jian-Min; Teranishi, Yoshiaki; Lin, Sheng Hsien

    2012-09-01

    Herein, we propose a modified version of the Wako-Saitô-Muñoz-Eaton (WSME) model. The proposed model introduces an empirical temperature parameter for the hypothetical structural units (i.e., foldons) in proteins to include site-dependent thermodynamic behavior. The thermodynamics for both our proposed model and the original WSME model were investigated. For a system with beta-hairpin topology, a mathematical treatment (contact-pair treatment) to facilitate the calculation of its partition function was developed. The results show that the proposed model provides better insight into the site-dependent thermodynamic behavior of the system, compared with the original WSME model. From this site-dependent point of view, the relationship between probe-dependent experimental results and model's thermodynamic predictions can be explained. The model allows for suggesting a general principle to identify foldon behavior. We also find that the backbone hydrogen bonds may play a role of structural constraints in modulating the cooperative system. Thus, our study may contribute to the understanding of the fundamental principles for the thermodynamics of protein folding.

  5. Holistic versus monomeric strategies for hydrological modelling of human-modified hydrosystems

    Directory of Open Access Journals (Sweden)

    I. Nalbantis

    2011-03-01

    Full Text Available The modelling of human-modified basins that are inadequately measured constitutes a challenge for hydrological science. Often, models for such systems are detailed and hydraulics-based for only one part of the system while for other parts oversimplified models or rough assumptions are used. This is typically a bottom-up approach, which seeks to exploit knowledge of hydrological processes at the micro-scale at some components of the system. Also, it is a monomeric approach in two ways: first, essential interactions among system components may be poorly represented or even omitted; second, differences in the level of detail of process representation can lead to uncontrolled errors. Additionally, the calibration procedure merely accounts for the reproduction of the observed responses using typical fitting criteria. The paper aims to raise some critical issues, regarding the entire modelling approach for such hydrosystems. For this, two alternative modelling strategies are examined that reflect two modelling approaches or philosophies: a dominant bottom-up approach, which is also monomeric and, very often, based on output information, and a top-down and holistic approach based on generalized information. Critical options are examined, which codify the differences between the two strategies: the representation of surface, groundwater and water management processes, the schematization and parameterization concepts and the parameter estimation methodology. The first strategy is based on stand-alone models for surface and groundwater processes and for water management, which are employed sequentially. For each model, a different (detailed or coarse parameterization is used, which is dictated by the hydrosystem schematization. The second strategy involves model integration for all processes, parsimonious parameterization and hybrid manual-automatic parameter optimization based on multiple objectives. A test case is examined in a hydrosystem in Greece

  6. Modeling thermal performance of exterior walls retrofitted from insulation and modified laterite based bricks materials

    Science.gov (United States)

    Wati, Elvis; Meukam, Pierre; Damfeu, Jean Claude

    2017-12-01

    Uninsulated concrete block walls commonly found in tropical region have to be retrofitted to save energy. The thickness of insulation layer used can be reduced with the help of modified laterite based bricks layer (with the considerably lower thermal conductivity than that of concrete block layer) during the retrofit building fabrics. The aim of this study is to determine the optimum location and distribution of different materials. The investigation is carried out under steady periodic conditions under the climatic conditions of Garoua in Cameroon using a Simulink model constructed from H-Tools (the library of Simulink models). Results showed that for the continuous air-conditioned space, the best wall configuration from the maximum time lag, minimum decrement factor and peak cooling transmission load perspective, is dividing the insulation layer into two layers and placing one at the exterior surface and the other layer between the two different massive layers with the modified laterite based bricks layer at the interior surface. For intermittent cooling space, the best wall configuration from the minimum energy consumption depends on total insulation thickness. For the total insulation thickness less than 8 cm approximately, the best wall configuration is placing the half layer of insulation material at the interior surface and the other half between the two different massive layers with the modified earthen material at the exterior surface. Results also showed that, the optimum insulation thickness calculated from the yearly cooling transmission (estimated only during the occupied period) and some economic considerations slightly depends on the location of that insulation.

  7. Contemporary challenges in applying of the modified model CAPM with country risk premium in emerging economies

    Directory of Open Access Journals (Sweden)

    Petrović Dragana

    2017-01-01

    Full Text Available Modern approach in determining the expected return of foreign investors' investments is based on the evaluation investment in capital asset-CAPM (Capital Asset Pricing Model. In order to use the CAPM model for calculating the expected return of foreign investors in growing economies, it is developed the extended model CAPM with the risk premium in the country. This variant of the CAPM model has been used for estimating the cost of capital. This is the expected return on a portfolio of the company's stocks in less developed countries. Those countries have certain problems and factors of risk investment. This research examines the limitations and shortcomings in the application of the extended model with country risk premium, during the calculation of the cost of capital in the less developed economies. We present possible models to overcome those problems and also a need for upgrading of modified CAPM model with a risk premium of the country which, beside risk of the country (CR must have a discount for the 'advantage of the country'.

  8. Astronomical Constraints on Some Long-Range Models of Modified Gravity

    Directory of Open Access Journals (Sweden)

    Lorenzo Iorio

    2007-01-01

    Full Text Available We use the corrections to the Newton-Einstein secular precessions of the longitudes of the perihelia of the inner planets, phenomenologically estimated E.V. Pitjeva by fitting almost one century of data with the EPM2004 ephemerides, to constrain some long-range models of modified gravity recently put forth to address the dark energy and dark matter problems. They are the four-dimensional ones obtained with the addition of inverse powers and logarithm of some curvature invariants, and the DGP multidimensional braneworld model. After working out the analytical expressions of the secular perihelion precessions induced by the corrections to the Newtonian potential of such models, we compare them to the estimated extra-rates of perihelia by taking their ratio for different pairs of planets instead of using one perihelion at a time for each planet separately, as done so far in literature. The curvature invariants-based models are ruled out, even by rescaling by a factor 10 the errors in the estimated planetary orbital parameters. Less neat is the situation for the DGP model. Only the general relativistic Lense-Thirring effect, not included, as the other exotic models considered here, by Pitjeva in the EPM force models, passes such a test.

  9. Preparation and characterization of physically modified glass beads used as model carriers in dry powder inhalers.

    Science.gov (United States)

    Zellnitz, Sarah; Redlinger-Pohn, Jakob Dominik; Kappl, Michael; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2013-04-15

    The aim of this work is the physical modification and characterization of the surface topography of glass beads used as model carriers in dry powder inhalers (DPIs). By surface modification the contact area between drug and carrier and thereby interparticle forces may be modified. Thus the performance of DPIs that relies on interparticle interactions may be improved. Glass beads were chosen as model carriers because various prospects of physical surface modification may be applied without affecting other factors also impacting interparticle interactions like particle size and shape. To generate rough surfaces glass beads were processed mechanically by friction and impaction in a ball mill with different grinding materials that were smaller and harder with respect to the glass beads. By varying the grinding time (4 h, 8 h) and by using different grinding media (tungsten carbide, quartz) surfaces with different shades of roughness were generated. Depending on the hardness of the grinding material and the grinding time the surface roughness was more or less pronounced. Surface roughness parameters and specific surface area were determined via several complementary techniques in order to get an enhanced understanding of the impact of the modifying procedure on the surface properties of the glass beads. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Immediate effects of modified landing pattern on a probabilistic tibial stress fracture model in runners.

    Science.gov (United States)

    Chen, T L; An, W W; Chan, Z Y S; Au, I P H; Zhang, Z H; Cheung, R T H

    2016-03-01

    Tibial stress fracture is a common injury in runners. This condition has been associated with increased impact loading. Since vertical loading rates are related to the landing pattern, many heelstrike runners attempt to modify their footfalls for a lower risk of tibial stress fracture. Such effect of modified landing pattern remains unknown. This study examined the immediate effects of landing pattern modification on the probability of tibial stress fracture. Fourteen experienced heelstrike runners ran on an instrumented treadmill and they were given augmented feedback for landing pattern switch. We measured their running kinematics and kinetics during different landing patterns. Ankle joint contact force and peak tibial strains were estimated using computational models. We used an established mathematical model to determine the effect of landing pattern on stress fracture probability. Heelstrike runners experienced greater impact loading immediately after landing pattern switch (Ptibial strains and the risk of tibial stress fracture in runners with different landing patterns (P>0.986). Immediate transitioning of the landing pattern in heelstrike runners may not offer timely protection against tibial stress fracture, despite a reduction of impact loading. Long-term effects of landing pattern switch remains unknown. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

    Science.gov (United States)

    Nayak, Bishnupriya; Menon, S. V. G.

    2018-01-01

    Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

  12. A modified QWASI model for fate and transport modeling of mercury between the water-ice-sediment in Lake Ulansuhai.

    Science.gov (United States)

    Liu, Yu; Li, Changyou; Anderson, Bruce; Zhang, Sheng; Shi, Xiaohong; Zhao, Shengnan

    2017-06-01

    Mercury contamination from industrial and agricultural drainage into lakes and rivers is a growing concern in Northern China. Lake Ulansuhai, located in Hetao irrigation district in Inner Mongolia, is the only sink for the all industrial and agricultural drainage and sole outlet for this district to the Yellow River, which is one of the main source of drinking water for the numerous cities and towns downstream. Because Ulansuahi is ice-covered during winter, the QWASI model was modified by adding an ice equation to get a more accurate understanding of the fate and transport of mercury within the lake. Both laboratory and field tests were carried out during the ice growth period. The aquivalence and mass balance approaches were used to develop the modified QWASI + ice model. The margins of error between the modelled and the measured average concentrations of Hg in ice, water, and sediment were 30%, 26.2%, and 19.8% respectively. These results suggest that the new QWASI + ice model could be used to more accurately represent the fate and transport of mercury in the seasonally ice-covered lakes, during the ice growth period. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Sensitivity analysis and parameter estimation for distributed hydrological modeling: potential of variational methods

    Directory of Open Access Journals (Sweden)

    W. Castaings

    2009-04-01

    Full Text Available Variational methods are widely used for the analysis and control of computationally intensive spatially distributed systems. In particular, the adjoint state method enables a very efficient calculation of the derivatives of an objective function (response function to be analysed or cost function to be optimised with respect to model inputs.

    In this contribution, it is shown that the potential of variational methods for distributed catchment scale hydrology should be considered. A distributed flash flood model, coupling kinematic wave overland flow and Green Ampt infiltration, is applied to a small catchment of the Thoré basin and used as a relatively simple (synthetic observations but didactic application case.

    It is shown that forward and adjoint sensitivity analysis provide a local but extensive insight on the relation between the assigned model parameters and the simulated hydrological response. Spatially distributed parameter sensitivities can be obtained for a very modest calculation effort (~6 times the computing time of a single model run and the singular value decomposition (SVD of the Jacobian matrix provides an interesting perspective for the analysis of the rainfall-runoff relation.

    For the estimation of model parameters, adjoint-based derivatives were found exceedingly efficient in driving a bound-constrained quasi-Newton algorithm. The reference parameter set is retrieved independently from the optimization initial condition when the very common dimension reduction strategy (i.e. scalar multipliers is adopted.

    Furthermore, the sensitivity analysis results suggest that most of the variability in this high-dimensional parameter space can be captured with a few orthogonal directions. A parametrization based on the SVD leading singular vectors was found very promising but should be combined with another regularization strategy in order to prevent overfitting.

  14. Transport Modeling of Modified Magnetite Nanoparticles with Sodium Dodecyl Sulfate in a Saturated Sandy Soil

    Directory of Open Access Journals (Sweden)

    Ahmad Farrokhian Firouzi

    2017-02-01

    . The response curve was followed by analyzing the concentration history of Cl-1 in the effluent. Then, the influent was switched back to the background solution to thoroughly elute the tracer. Following the tracer test, a modified magnetite nanoparticles with sodium dodecyl sulfate was introduced into the column and the nanoparticle breakthrough curves were obtained by measuring the concentration history of total Fe in the effluent. Total iron concentration was analyzed with a flame atomic-absorption spectrophotometer. One site and two site kinetic attachment-detachment models in HYDRUS-1D software were used to predict the nanoparticles transport. Also parameters of model efficiency coefficient (E, root mean square error (RMSE, geometric mean error ratio (GMER, and geometric standard deviation of error ratio (GSDER were used to determine the accuracy of the models. Results and Discussion: SEM measurements demonstrated that the particle size of nanoparticles was about 40-60 nm. The hydrodynamic dispersion coefficient (D for each medium was obtained by fitting the classic 1-D convection–dispersion equation (CDE to the experimental breakthrough data using the CXTFIT code (STANMOD software, USDA. The relative concentration of nanoparticles in comparison with chloride in the collected effluent from soil columns were much lower indicating a strong retention of nanoparticles in studied porous media, thereby attachment, deposition and possibly straining of nanoparticles. Modeling results showed that in all sites of both models (one site and two-site kinetic attachment-detachment models, attachment was rapid and detachment was slow. These attachment kinetic sites may be because of consistent charges of minerals with attachment. Therefore, considering to same attachment-detachment behavior in two sites of two-site kinetic model, it is concluded that the one site kinetic model had eligible estimation of nanoparticles breakthrough curve in the studied sandy soil columns lonely

  15. Modified Hyperspheres Algorithm to Trace Homotopy Curves of Nonlinear Circuits Composed by Piecewise Linear Modelled Devices

    Directory of Open Access Journals (Sweden)

    H. Vazquez-Leal

    2014-01-01

    Full Text Available We present a homotopy continuation method (HCM for finding multiple operating points of nonlinear circuits composed of devices modelled by using piecewise linear (PWL representations. We propose an adaptation of the modified spheres path tracking algorithm to trace the homotopy trajectories of PWL circuits. In order to assess the benefits of this proposal, four nonlinear circuits composed of piecewise linear modelled devices are analysed to determine their multiple operating points. The results show that HCM can find multiple solutions within a single homotopy trajectory. Furthermore, we take advantage of the fact that homotopy trajectories are PWL curves meant to replace the multidimensional interpolation and fine tuning stages of the path tracking algorithm with a simple and highly accurate procedure based on the parametric straight line equation.

  16. Modelling the autoxidation of myoglobin in fresh meat under modified atmosphere packing conditions

    DEFF Research Database (Denmark)

    Tofteskov, Jon; Hansen, Jesper Schmidt; Bailey, Nicholas

    2017-01-01

    pigment concentration data is obtained, but only by substantially increasing the value of the oxygen consumption rate. Application of the model to meat stored at 5 °C shows that the metmyoglobin layer forms under the surface over a time scale of 24 h; The metmyoglobin layer forms deeper inside the meat......Modified atmosphere packing (MAP) is a technique to increase the shelf life of fresh meat. Continuing development of MAP requires better understanding of the physical and chemical processes taking place, in particular the diffusion of oxygen and its reaction with myoglobin. We model these processes...... proportional to the logarithm of the headspace oxygen partial pressure, thus improving the colour appearance of the meat....

  17. Fast three-dimensional core optimization based on modified one-group model

    Energy Technology Data Exchange (ETDEWEB)

    Freire, Fernando S. [ELETROBRAS Termonuclear S.A. - ELETRONUCLEAR, Rio de Janeiro, RJ (Brazil). Dept. GCN-T], e-mail: freire@eletronuclear.gov.br; Martinez, Aquilino S.; Silva, Fernando C. da [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear], e-mail: aquilino@con.ufrj.br, e-mail: fernando@con.ufrj.br

    2009-07-01

    The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)

  18. Matter density perturbations in modified gravity models with arbitrary coupling between matter and geometry

    DEFF Research Database (Denmark)

    Nesseris, Savvas

    2009-01-01

    We consider theories with an arbitrary coupling between matter and gravity and obtain the perturbation equation of matter on subhorizon scales. Also, we derive the effective gravitational constant $G_{eff}$ and two parameters $\\Sigma$ and $\\eta$, which along with the perturbation equation...... of the matter density are useful to constrain the theory from growth factor and weak lensing observations. Finally, we use a completely solvable toy model which exhibits nontrivial phenomenology to investigate specific features of the theory. We obtain the analytic solution of the modified Friedmann equation...... for the scale factor $a$ in terms of time $t$ and use the age of the oldest star clusters and the primordial nucleosynthesis bounds in order to constrain the parameters of our toy model....

  19. Matter density perturbations in modified gravity models with arbitrary coupling between matter and geometry

    International Nuclear Information System (INIS)

    Nesseris, Savvas

    2009-01-01

    We consider theories with an arbitrary coupling between matter and gravity and obtain the perturbation equation of matter on subhorizon scales. Also, we derive the effective gravitational constant G eff and two parameters Σ and η, which along with the perturbation equation of the matter density are useful to constrain the theory from growth factor and weak lensing observations. Finally, we use a completely solvable toy model which exhibits nontrivial phenomenology to investigate specific features of the theory. We obtain the analytic solution of the modified Friedmann equation for the scale factor a in terms of time t and use the age of the oldest star clusters and the primordial nucleosynthesis bounds in order to constrain the parameters of our toy model.

  20. Fast three-dimensional core optimization based on modified one-group model

    International Nuclear Information System (INIS)

    Freire, Fernando S.; Martinez, Aquilino S.; Silva, Fernando C. da

    2009-01-01

    The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)

  1. The KdV—Burgers equation in a modified speed gradient continuum model

    International Nuclear Information System (INIS)

    Lai Ling-Ling; Ge Hong-Xia; Cheng Rong-Jun; Li Zhi-Peng

    2013-01-01

    Based on the full velocity difference model, Jiang et al. put forward the speed gradient model through the micro-macro linkage (Jiang R, Wu Q S and Zhu Z J 2001 Chin. Sci. Bull. 46 345 and Jiang R, Wu Q S and Zhu Z J 2002 Trans. Res. B 36 405). In this paper, the Taylor expansion is adopted to modify the model. The backward travel problem is overcome by our model, which exists in many higher-order continuum models. The neutral stability condition of the model is obtained through the linear stability analysis. Nonlinear analysis shows clearly that the density fluctuation in traffic flow leads to a variety of density waves. Moreover, the Korteweg-de Vries—Burgers (KdV—Burgers) equation is derived to describe the traffic flow near the neutral stability line and the corresponding solution for traffic density wave is derived. The numerical simulation is carried out to investigate the local cluster effects. The results are consistent with the realistic traffic flow and also further verify the results of nonlinear analysis

  2. Stability and Optimal Harvesting of Modified Leslie-Gower Predator-Prey Model

    Science.gov (United States)

    Toaha, S.; Azis, M. I.

    2018-03-01

    This paper studies a modified of dynamics of Leslie-Gower predator-prey population model. The model is stated as a system of first order differential equations. The model consists of one predator and one prey. The Holling type II as a predation function is considered in this model. The predator and prey populations are assumed to be beneficial and then the two populations are harvested with constant efforts. Existence and stability of the interior equilibrium point are analysed. Linearization method is used to get the linearized model and the eigenvalue is used to justify the stability of the interior equilibrium point. From the analyses, we show that under a certain condition the interior equilibrium point exists and is locally asymptotically stable. For the model with constant efforts of harvesting, cost function, revenue function, and profit function are considered. The stable interior equilibrium point is then related to the maximum profit problem as well as net present value of revenues problem. We show that there exists a certain value of the efforts that maximizes the profit function and net present value of revenues while the interior equilibrium point remains stable. This means that the populations can live in coexistence for a long time and also maximize the benefit even though the populations are harvested with constant efforts.

  3. Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balances

    Directory of Open Access Journals (Sweden)

    G. Tang

    2012-08-01

    Full Text Available Satellite-based data, such as vegetation type and fractional vegetation cover, are widely used in hydrologic models to prescribe the vegetation state in a study region. Dynamic global vegetation models (DGVM simulate land surface hydrology. Incorporation of satellite-based data into a DGVM may enhance a model's ability to simulate land surface hydrology by reducing the task of model parameterization and providing distributed information on land characteristics. The objectives of this study are to (i modify a DGVM for simulating land surface water balances; (ii evaluate the modified model in simulating actual evapotranspiration (ET, soil moisture, and surface runoff at regional or watershed scales; and (iii gain insight into the ability of both the original and modified model to simulate large spatial scale land surface hydrology. To achieve these objectives, we introduce the "LPJ-hydrology" (LH model which incorporates satellite-based data into the Lund-Potsdam-Jena (LPJ DGVM. To evaluate the model we ran LH using historical (1981–2006 climate data and satellite-based land covers at 2.5 arc-min grid cells for the conterminous US and for the entire world using coarser climate and land cover data. We evaluated the simulated ET, soil moisture, and surface runoff using a set of observed or simulated data at different spatial scales. Our results demonstrate that spatial patterns of LH-simulated annual ET and surface runoff are in accordance with previously published data for the US; LH-modeled monthly stream flow for 12 major rivers in the US was consistent with observed values respectively during the years 1981–2006 (R2 > 0.46, p < 0.01; Nash-Sutcliffe Coefficient > 0.52. The modeled mean annual discharges for 10 major rivers worldwide also agreed well (differences < 15% with observed values for these rivers. Compared to a degree-day method for snowmelt computation, the addition of the solar radiation effect on snowmelt

  4. Kinetics Modeling and Isotherms for Adsorption of Phosphate from Aqueous Solution by Modified Clinoptilolit

    Directory of Open Access Journals (Sweden)

    Mohammad Malakootian

    2012-01-01

    Full Text Available The Phosphorous discharge into the surface water led to excessive growth of algae and eutrophication in lakes and rivers. Therefore the phosphorus removal is important due to negative effect on water resources. The aim of this study was to investigat the modification of clinoptilolite and application of modified clinoptilolite for phosphorous adsorption from aqueous solution and isotherms and kinetics modeling. Hexadecyl Trimethyl Ammonium bromide (HDTMA-Br, Hexadecyl trimethyl Ammonium Chloride (HDTMA-Cl, Sodium Decyl Sulphate (SDS and Cetrimide-C were used for modification of clinoptilolite. Experiments were conducted using jar apparatus and batch system. The effect of pH, adsorbent doses, contact time, phosphate initial concentration and particle size were studied surveyed on phosphate adsorption by modified clinoptilolite. The most common isotherms and the kinetics adsorption equations were used for determination of adsorption rate and dynamic reaction. The results showed that maximum phosphate adsorption was obtained in the pH of 7 and contact time 90min. Also it was found with the increasing of phosphate initial concentration, phosphate removal efficiency decreased significantly. Langmuir No 2 showed a good correlation compared to other isotherms (R2=0.997. Maximum adsorption capacity was obtained in 20g/L adsorbent dose (22.73mg/g. Also Interaparticle diffusion kinetics well fits with experimental data (R2=0.999 with constant rate of 3.84mg/g min0.5. The result showed that modified clinoptilolite can be used successfully as low cost and effective absorbent for phosphate removal.

  5. Development of a modified equilibrium model for biomass pilot-scale fluidized bed gasifier performance predictions

    International Nuclear Information System (INIS)

    Rodriguez-Alejandro, David A.; Nam, Hyungseok; Maglinao, Amado L.; Capareda, Sergio C.; Aguilera-Alvarado, Alberto F.

    2016-01-01

    The objective of this work is to develop a thermodynamic model considering non-stoichiometric restrictions. The model validation was done from experimental works using a bench-scale fluidized bed gasifier with wood chips, dairy manure, and sorghum. The model was used for a further parametric study to predict the performance of a pilot-scale fluidized biomass gasifier. The Gibbs free energy minimization was applied to the modified equilibrium model considering a heat loss to the surroundings, carbon efficiency, and two non-equilibrium factors based on empirical correlations of ER and gasification temperature. The model was in a good agreement with RMS <4 for the produced gas. The parametric study ranges were 0.01 < ER < 0.99 and 500 °C < T < 900 °C to predict syngas concentrations and its LHV (lower heating value) for the optimization. Higher aromatics in tar were contained in WC gasification compared to manure gasification. A wood gasification tar simulation was produced to predict the amount of tars at specific conditions. The operating conditions for the highest quality syngas were reconciled experimentally with three biomass wastes using a fluidized bed gasifier. The thermodynamic model was used to predict the gasification performance at conditions beyond the actual operation. - Highlights: • Syngas from experimental gasification was used to create a non-equilibrium model. • Different types of biomass (HTS, DM, and WC) were used for gasification modelling. • Different tar compositions were identified with a simulation of tar yields. • The optimum operating conditions were found through the developed model.

  6. 47 CFR 76.1905 - Petitions to modify encoding rules for new services within defined business models.

    Science.gov (United States)

    2010-10-01

    ... services within defined business models. 76.1905 Section 76.1905 Telecommunication FEDERAL COMMUNICATIONS... Rules § 76.1905 Petitions to modify encoding rules for new services within defined business models. (a) The encoding rules for defined business models in § 76.1904 reflect the conventional methods for...

  7. Heating and cooling building energy demand evaluation; a simplified model and a modified degree days approach

    International Nuclear Information System (INIS)

    De Rosa, Mattia; Bianco, Vincenzo; Scarpa, Federico; Tagliafico, Luca A.

    2014-01-01

    Highlights: • A dynamic model to estimate the energy performance of buildings is presented. • The model is validated against leading software packages, TRNSYS and Energy Plus. • Modified degree days are introduced to account for solar irradiation effects. - Abstract: Degree days represent a versatile climatic indicator which is commonly used in building energy performance analysis. In this context, the present paper proposes a simple dynamic model to simulate heating/cooling energy consumption in buildings. The model consists of several transient energy balance equations for external walls and internal air according to a lumped-capacitance approach and it has been implemented utilizing the Matlab/Simulink® platform. Results are validated by comparison to the outcomes of leading software packages, TRNSYS and Energy Plus. By using the above mentioned model, energy consumption for heating/cooling is analyzed in different locations, showing that for low degree days the inertia effect assumes a paramount importance, affecting the common linear behavior of the building consumption against the standard degree days, especially for cooling energy demand. Cooling energy demand at low cooling degree days (CDDs) is deeply analyzed, highlighting that in this situation other factors, such as solar irradiation, have an important role. To take into account these effects, a correction to CDD is proposed, demonstrating that by considering all the contributions the linear relationship between energy consumption and degree days is maintained

  8. Ratchetting deformation behavior of modified 9Cr-1Mo steel and applicability of existing constitutive models

    International Nuclear Information System (INIS)

    Yaguchi, Masatsugu; Takahashi, Yukio

    2001-01-01

    A series of ratchetting deformation tests was conducted on modified 9Cr-1Mo steel at 550degC under uniaxial and multiaxial stress conditions. Ratchetting behavior depended on various parameters such as mean stress, stress/strain rate and those range, hold time and prior cyclic deformation. Under uniaxial conditions, untraditional ratchetting behavior was observed; the ratchetting deformation rate was the fastest when the stress ratio was equal to -1, while no ratchetting deformation was predicted by conventional constitutive models. In order to discuss the reason for this untraditional ratchetting behavior, a lot of monotonic compression tests were conducted and compared with tension data. The material showed a difference of deformation resistance of about 30 MPa between tension and compression at high strain rates. Furthermore, the authors' previous model and Ohno-Wang model were applied to the test conditions to evaluate their description capability for ratchetting behavior of the material. It was shown that the authors' model has a tendency to overestimate the ratchetting deformation and that the Ohno-Wang model has a tendency to underestimate the uniaxial ratchetting deformation at small stress rates. (author)

  9. A modified receptor model for source apportionment of heavy metal pollution in soil.

    Science.gov (United States)

    Huang, Ying; Deng, Meihua; Wu, Shaofu; Japenga, Jan; Li, Tingqiang; Yang, Xiaoe; He, Zhenli

    2018-07-15

    Source apportionment is a crucial step toward reduction of heavy metal pollution in soil. Existing methods are generally based on receptor models. However, overestimation or underestimation occurs when they are applied to heavy metal source apportionment in soil. Therefore, a modified model (PCA-MLRD) was developed, which is based on principal component analysis (PCA) and multiple linear regression with distance (MLRD). This model was applied to a case study conducted in a peri-urban area in southeast China where soils were contaminated by arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb). Compared with existing models, PCA-MLRD is able to identify specific sources and quantify the extent of influence for each emission. The zinc (Zn)-Pb mine was identified as the most important anthropogenic emission, which affected approximately half area for Pb and As accumulation, and approximately one third for Cd. Overall, the influence extent of the anthropogenic emissions decreased in the order of mine (3 km) > dyeing mill (2 km) ≈ industrial hub (2 km) > fluorescent factory (1.5 km) > road (0.5 km). Although algorithm still needs to improved, the PCA-MLRD model has the potential to become a useful tool for heavy metal source apportionment in soil. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Hot nuclear matter in the modified quark-meson coupling model with quark-quark correlations

    International Nuclear Information System (INIS)

    Zakout, I.; Jaqaman, H.R.

    2000-01-01

    Short-range quark-quark correlations in hot nuclear matter are examined within the modified quark-meson coupling (MQMC) model by adding repulsive scalar and vector quark-quark interactions. Without these correlations, the bag radius increases with the baryon density. However, when the correlations are introduced the bag size shrinks as the bags overlap. Also as the strength of the scalar quark-quark correlation is increased, the decrease of the effective nucleon mass M* N with the baryonic density is slowed down and tends to saturate at high densities. Within this model we study the phase transition from the baryon-meson phase to the quark-gluon plasma (QGP) phase with the latter modelled as an ideal gas of quarks and gluons inside a bag. Two models for the QGP bag parameter are considered. In one case, the bag is taken to be medium-independent and the phase transition from the hadron phase to QGP is found to occur at five to eight times ordinary nuclear matter density for temperatures less than 60 MeV. For lower densities, the transition takes place at a higher temperature, reaching up to 130 MeV at zero density. In the second case, the QGP bag parameter is considered to be medium-dependent as in the MQMC model for the hadronic phase. In this case, it is found that the phase transition occurs at much lower densities. (author)

  11. Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balance

    Science.gov (United States)

    Tang, G.; Bartlein, P. J.

    2012-01-01

    Water balance models of simple structure are easier to grasp and more clearly connect cause and effect than models of complex structure. Such models are essential for studying large spatial scale land surface water balance in the context of climate and land cover change, both natural and anthropogenic. This study aims to (i) develop a large spatial scale water balance model by modifying a dynamic global vegetation model (DGVM), and (ii) test the model's performance in simulating actual evapotranspiration (ET), soil moisture and surface runoff for the coterminous United States (US). Toward these ends, we first introduced development of the "LPJ-Hydrology" (LH) model by incorporating satellite-based land covers into the Lund-Potsdam-Jena (LPJ) DGVM instead of dynamically simulating them. We then ran LH using historical (1982-2006) climate data and satellite-based land covers at 2.5 arc-min grid cells. The simulated ET, soil moisture and surface runoff were compared to existing sets of observed or simulated data for the US. The results indicated that LH captures well the variation of monthly actual ET (R2 = 0.61, p 0.46, p 0.52) with observed values over the years 1982-2006, respectively. The modeled spatial patterns of annual ET and surface runoff are in accordance with previously published data. Compared to its predecessor, LH simulates better monthly stream flow in winter and early spring by incorporating effects of solar radiation on snowmelt. Overall, this study proves the feasibility of incorporating satellite-based land-covers into a DGVM for simulating large spatial scale land surface water balance. LH developed in this study should be a useful tool for studying effects of climate and land cover change on land surface hydrology at large spatial scales.

  12. Modeling of thermal conductivity of nanofluids by modifying Maxwell’s equation using cell model approach

    International Nuclear Information System (INIS)

    Mehta, Siddharth; Chauhan, K. Prashanth; Kanagaraj, S.

    2011-01-01

    Nanofluid is an innovative heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids. Though many attempts have been made to investigate the abnormal high thermal conductivity of nanofluids, the existing models cannot precisely predict the same. An attempt has been made to develop a model for predicting the thermal conductivity of different types of nanofluids. The model presented here is derived based on the fact that thermal conductivity of nanofluids depends on thermal conductivity of particle and fluid as well as micro-convective heat transfer due to Brownian motion of nanoparticles. Novelty of the article lies in giving a unique equation which predicts thermal conductivity of nanofluids for different concentrations and particle sizes which also correctly predicts the trends observed in experimental data over a wide range of particle sizes, temperatures, and particle concentrations.

  13. Modelling Particulate Removal in Tubular Wet Electrostatic Precipitators Using a Modified Drift Flux Model

    Directory of Open Access Journals (Sweden)

    S Ramechecandane

    2016-09-01

    Full Text Available Tubular electrostatic precipitators (ESP have been used in a number of chemical processing industries. The tubular ESPs have many advantages over conventional plate-plate and wire-plate ESPs. The present study is concerned with the numerical modeling of particulate removal in a tubular wet single-stage electrostatic precipitator (wESP. The geometric parameters of a model wESP and the corresponding inlet gas velocities for the wESP are chosen from available experimental data. In addition to the RNG k - ε model for the mean turbulent flow field inside the wESP, the Poisson equation for the electric field, the charge continuity equation and the concentration equation are solved sequentially to obtain a full-fledged solution to the problem under investigation. The proposed drift flux model is implemented in the opensource CFD code OpenFOAM®. The paper discusses the influence of the number of charges acquired by the particles and the corresponding inlet gas velocities on particle concentration distribution within the wESP. Two representative cases with monodispersed particles of 1 μm and 10 μm diameter are considered for the numerical analysis. It is seen from the present analysis that the number of units of charge on particles, the particle size and the inlet gas velocities play a vital role in determining the efficiency of electrostatic precipitation.

  14. Determining the Walker exponent and developing a modified Smith-Watson-Topper parameter model

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Zhiqiang; Huang, Hong Zhong; Wang, Hai Kun; Gao, Huiying; Zuo, Fang Jun [University of Electronic Science and Technology of China, Chengdu (China)

    2016-03-15

    Mean stress effects significantly influence the fatigue life of components. In general, tensile mean stresses are known to reduce the fatigue life of components, whereas compressive mean stresses are known to increase it. To date, various methods that account for mean stress effects have been studied. In this research, considering the high accuracy of mean stress correction and the difficulty in obtaining the material parameter of the Walker method, a practical method is proposed to describe the material parameter of this method. The test data of various materials are then used to verify the proposed practical method. Furthermore, by applying the Walker material parameter and the Smith-Watson-Topper (SWT) parameter, a modified strain-life model is developed to consider sensitivity to mean stress of materials. In addition, three sets of experimental fatigue data from super alloy GH4133, aluminum alloy 7075-T651, and carbon steel are used to estimate the accuracy of the proposed model. A comparison is also made between the SWT parameter method and the proposed strainlife model. The proposed strain-life model provides more accurate life prediction results than the SWT parameter method.

  15. Simulation of emotional contagion using modified SIR model: A cellular automaton approach

    Science.gov (United States)

    Fu, Libi; Song, Weiguo; Lv, Wei; Lo, Siuming

    2014-07-01

    Emotion plays an important role in the decision-making of individuals in some emergency situations. The contagion of emotion may induce either normal or abnormal consolidated crowd behavior. This paper aims to simulate the dynamics of emotional contagion among crowds by modifying the epidemiological SIR model to a cellular automaton approach. This new cellular automaton model, entitled the “CA-SIRS model”, captures the dynamic process ‘susceptible-infected-recovered-susceptible', which is based on SIRS contagion in epidemiological theory. Moreover, in this new model, the process is integrated with individual movement. The simulation results of this model show that multiple waves and dynamical stability around a mean value will appear during emotion spreading. It was found that the proportion of initial infected individuals had little influence on the final stable proportion of infected population in a given system, and that infection frequency increased with an increase in the average crowd density. Our results further suggest that individual movement accelerates the spread speed of emotion and increases the stable proportion of infected population. Furthermore, decreasing the duration of an infection and the probability of reinfection can markedly reduce the number of infected individuals. It is hoped that this study will be helpful in crowd management and evacuation organization.

  16. HYDROGEIOS: a semi-distributed GIS-based hydrological model for modified river basins

    Directory of Open Access Journals (Sweden)

    A. Efstratiadis

    2008-07-01

    Full Text Available The HYDROGEIOS modelling framework represents the main processes of the hydrological cycle in heavily modified catchments, with decision-depended abstractions and interactions between surface and groundwater flows. A semi-distributed approach and a monthly simulation time step are adopted, which are sufficient for water resources management studies. The modelling philosophy aims to ensure consistency with the physical characteristics of the system, while keeping the number of parameters as low as possible. Therefore, multiple levels of schematization and parameterization are adopted, by combining multiple levels of geographical data. To optimally allocate human abstractions from the hydrosystem during a planning horizon or even to mimic the allocation occurred in a past period (e.g. the calibration period, in the absence of measured data, a linear programming problem is formulated and solved within each time step. With this technique the fluxes across the hydrosystem are estimated, and the satisfaction of physical and operational constraints is ensured. The model framework includes a parameter estimation module that involves various goodness-of-fit measures and state-of-the-art evolutionary algorithms for global and multiobjective optimization. By means of a challenging case study, the paper discusses appropriate modelling strategies which take advantage of the above framework, with the purpose to ensure a robust calibration and reproduce natural and human induced processes in the catchment as faithfully as possible.

  17. The application of extended modified Lambert Beer model for measurement of blood carboxyhemoglobin and oxyhemoglobin saturation

    Directory of Open Access Journals (Sweden)

    Audrey Huong

    2014-05-01

    Full Text Available This work presents the use of extended Modified Lambert Beer (MLB model for accurate and continuous monitoring of percent blood carboxyhemoglobin (COHb (SCO and oxyhemoglobin (OxyHb saturation (SO2 via a fitting procedure. This quantification technique is based on the absorption characteristics of hemoglobin derivatives in the wavelength range of 520–600 nm to give the best estimates of the required parameters. A comparison of the performance of the developed model and MLB law is made using attenuation data from Monte Carlo simulations for a two-layered skin model. The results revealed a lower mean absolute error of 0.4% in the values estimated by the developed model as compared to 10% that is given by the MLB law. This study showed that the discussed approach is able to provide consistent and accurate measurement of blood SO2 and SCO across different skin pigmentations suggesting that it may potentially be used as an alternative means for clinical diagnosis of carbon monoxide (CO poisoning.

  18. Development of a Modified Kernel Regression Model for a Robust Signal Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Ibrahim; Heo, Gyunyoung [Kyung Hee University, Yongin (Korea, Republic of)

    2016-10-15

    The demand for robust and resilient performance has led to the use of online-monitoring techniques to monitor the process parameters and signal validation. On-line monitoring and signal validation techniques are the two important terminologies in process and equipment monitoring. These techniques are automated methods of monitoring instrument performance while the plant is operating. To implementing these techniques, several empirical models are used. One of these models is nonparametric regression model, otherwise known as kernel regression (KR). Unlike parametric models, KR is an algorithmic estimation procedure which assumes no significant parameters, and it needs no training process after its development when new observations are prepared; which is good for a system characteristic of changing due to ageing phenomenon. Although KR is used and performed excellently when applied to steady state or normal operating data, it has limitation in time-varying data that has several repetition of the same signal, especially if those signals are used to infer the other signals. The convectional KR has limitation in correctly estimating the dependent variable when time-varying data with repeated values are used to estimate the dependent variable especially in signal validation and monitoring. Therefore, we presented here in this work a modified KR that can resolve this issue which can also be feasible in time domain. Data are first transformed prior to the Euclidian distance evaluation considering their slopes/changes with respect to time. The performance of the developed model is evaluated and compared with that of conventional KR using both the lab experimental data and the real time data from CNS provided by KAERI. The result shows that the proposed developed model, having demonstrated high performance accuracy than that of conventional KR, is capable of resolving the identified limitation with convectional KR. We also discovered that there is still need to further

  19. Sensory and rheological properties of transgenically and chemically modified starch ingredients as evaluated in a food product model

    DEFF Research Database (Denmark)

    Ahmt, T.; Wischmann, Bente; Blennow, A.

    2004-01-01

    gels with a higher tendency to retrograde and a low freeze/thaw stability as compared to starches with shorter amylopectin chains and lower phosphorous content. The textural properties of the food product model prepared from genetically and chemically modified starches were characterised by sensory......Starches derived from five genetically modified potato lines, two chemically modified potato starches and two native starches from potato and maize were subjected to physical and chemical analyses and their functionality evaluated in a milk-based food product model. The transgenic starches were...... and rheological analyses. To clearly visualise the effects of the modifications, data was evaluated by radar plots and multiple regression analysis (chemometrics). Genetically modified potato starches with longer amylopectin chains and increased phosphorous content gave a more gelled and a shorter texture...

  20. A Modified FCM Classifier Constrained by Conditional Random Field Model for Remote Sensing Imagery

    Directory of Open Access Journals (Sweden)

    WANG Shaoyu

    2016-12-01

    Full Text Available Remote sensing imagery has abundant spatial correlation information, but traditional pixel-based clustering algorithms don't take the spatial information into account, therefore the results are often not good. To this issue, a modified FCM classifier constrained by conditional random field model is proposed. Adjacent pixels' priori classified information will have a constraint on the classification of the center pixel, thus extracting spatial correlation information. Spectral information and spatial correlation information are considered at the same time when clustering based on second order conditional random field. What's more, the global optimal inference of pixel's classified posterior probability can be get using loopy belief propagation. The experiment shows that the proposed algorithm can effectively maintain the shape feature of the object, and the classification accuracy is higher than traditional algorithms.

  1. Effects of Δ baryon in hyperon stars in a modified quark meson coupling model

    International Nuclear Information System (INIS)

    Sahoo, H.S.; Mishra, R.N.; Panda, P.K.; Barik, N.

    2016-01-01

    Recent studies on the appearance of the Δ (1232) isobars in neutron stars has ignited much debate on the possibility of its existence in neutron stars satisfying the observational limit of 2 M_⊙. Given the fact that the presence of the Δ tends to soften the equation of state (EoS) and reduce the maximum mass, theoretical and observational contradictions have given rise to the so called Δ puzzle, similar to the hyperon puzzle. In the present work we develop the EoS for dense matter with the inclusion of the nucleons, hyperons and the Delta isobars and study the effects of such inclusion on stellar properties using a Modified Quark-Meson coupling model (MQMC)

  2. A modified Leslie-Gower predator-prey interaction model and parameter identifiability

    Science.gov (United States)

    Tripathi, Jai Prakash; Meghwani, Suraj S.; Thakur, Manoj; Abbas, Syed

    2018-01-01

    In this work, bifurcation and a systematic approach for estimation of identifiable parameters of a modified Leslie-Gower predator-prey system with Crowley-Martin functional response and prey refuge is discussed. Global asymptotic stability is discussed by applying fluctuation lemma. The system undergoes into Hopf bifurcation with respect to parameters intrinsic growth rate of predators (s) and prey reserve (m). The stability of Hopf bifurcation is also discussed by calculating Lyapunov number. The sensitivity analysis of the considered model system with respect to all variables is performed which also supports our theoretical study. To estimate the unknown parameter from the data, an optimization procedure (pseudo-random search algorithm) is adopted. System responses and phase plots for estimated parameters are also compared with true noise free data. It is found that the system dynamics with true set of parametric values is similar to the estimated parametric values. Numerical simulations are presented to substantiate the analytical findings.

  3. Particle correlations in the recombination model associated with modified Kuti-Weisskopf structure functions

    International Nuclear Information System (INIS)

    Takasugi, E.; Tata, X.

    1982-01-01

    The recombination model associated with modified Kuti-Weisskopf multiquark structure functions is used to analyze particle production by hadronic collisions. The justification of the use of the impulse approximation in these processes and the universal nature of the recombination process are discussed. Single-meson inclusive production in the fragmentation domains of the proton, the pion, and the kaon is used as an input to determine the primitive structure functions. Our parameter-free predictions for low-p/sub T/ multimeson and associated meson-baryon inclusive production are found to be in good agreement with a large amount of recently obtained correlation data. It is pointed out, however, that reactions involving multivalence recombination fall outside the scope of present considerations

  4. Modified Levenberg-Marquardt Method for RÖSSLER Chaotic System Fuzzy Modeling Training

    Science.gov (United States)

    Wang, Yu-Hui; Wu, Qing-Xian; Jiang, Chang-Sheng; Xue, Ya-Li; Fang, Wei

    Generally, fuzzy approximation models require some human knowledge and experience. Operator's experience is involved in the mathematics of fuzzy theory as a collection of heuristic rules. The main goal of this paper is to present a new method for identifying unknown nonlinear dynamics such as Rössler system without any human knowledge. Instead of heuristic rules, the presented method uses the input-output data pairs to identify the Rössler chaotic system. The training algorithm is a modified Levenberg-Marquardt (L-M) method, which can adjust the parameters of each linear polynomial and fuzzy membership functions on line, and do not rely on experts' experience excessively. Finally, it is applied to training Rössler chaotic system fuzzy identification. Comparing this method with the standard L-M method, the convergence speed is accelerated. The simulation results demonstrate the effectiveness of the proposed method.

  5. Dynamic Analysis of Thick Plates Including Deep Beams on Elastic Foundations Using Modified Vlasov Model

    Directory of Open Access Journals (Sweden)

    Korhan Ozgan

    2013-01-01

    Full Text Available Dynamic analysis of foundation plate-beam systems with transverse shear deformation is presented using modified Vlasov foundation model. Finite element formulation of the problem is derived by using an 8-node (PBQ8 finite element based on Mindlin plate theory for the plate and a 2-node Hughes element based on Timoshenko beam theory for the beam. Selective reduced integration technique is used to avoid shear locking problem for the evaluation of the stiffness matrices for both the elements. The effect of beam thickness, the aspect ratio of the plate and subsoil depth on the response of plate-beam-soil system is analyzed. Numerical examples show that the displacement, bending moments and shear forces are changed significantly by adding the beams.

  6. Itzï (version 17.1): an open-source, distributed GIS model for dynamic flood simulation

    Science.gov (United States)

    Guillaume Courty, Laurent; Pedrozo-Acuña, Adrián; Bates, Paul David

    2017-05-01

    Worldwide, floods are acknowledged as one of the most destructive hazards. In human-dominated environments, their negative impacts are ascribed not only to the increase in frequency and intensity of floods but also to a strong feedback between the hydrological cycle and anthropogenic development. In order to advance a more comprehensive understanding of this complex interaction, this paper presents the development of a new open-source tool named Itzï that enables the 2-D numerical modelling of rainfall-runoff processes and surface flows integrated with the open-source geographic information system (GIS) software known as GRASS. Therefore, it takes advantage of the ability given by GIS environments to handle datasets with variations in both temporal and spatial resolutions. Furthermore, the presented numerical tool can handle datasets from different sources with varied spatial resolutions, facilitating the preparation and management of input and forcing data. This ability reduces the preprocessing time usually required by other models. Itzï uses a simplified form of the shallow water equations, the damped partial inertia equation, for the resolution of surface flows, and the Green-Ampt model for the infiltration. The source code is now publicly available online, along with complete documentation. The numerical model is verified against three different tests cases: firstly, a comparison with an analytic solution of the shallow water equations is introduced; secondly, a hypothetical flooding event in an urban area is implemented, where results are compared to those from an established model using a similar approach; and lastly, the reproduction of a real inundation event that occurred in the city of Kingston upon Hull, UK, in June 2007, is presented. The numerical approach proved its ability at reproducing the analytic and synthetic test cases. Moreover, simulation results of the real flood event showed its suitability at identifying areas affected by flooding

  7. A Hybrid 3D Colon Segmentation Method Using Modified Geometric Deformable Models

    Directory of Open Access Journals (Sweden)

    S. Falahieh Hamidpour

    2007-06-01

    Full Text Available Introduction: Nowadays virtual colonoscopy has become a reliable and efficient method of detecting primary stages of colon cancer such as polyp detection. One of the most important and crucial stages of virtual colonoscopy is colon segmentation because an incorrect segmentation may lead to a misdiagnosis.  Materials and Methods: In this work, a hybrid method based on Geometric Deformable Models (GDM in combination with an advanced region growing and thresholding methods is proposed. GDM are found to be an attractive tool for structural based image segmentation particularly for extracting the objects with complicated topology. There are two main parameters influencing the overall performance of GDM algorithm; the distance between the initial contour and the actual object’s contours and secondly the stopping term which controls the deformation. To overcome these limitations, a two stage hybrid based segmentation method is suggested to extract the rough but precise initial contours at the first stage of the segmentation. The extracted boundaries are smoothed and improved using a modified GDM algorithm by improving the stopping terms of the algorithm based on the gradient value of image voxels. Results: The proposed algorithm was implemented on forty data sets each containing 400-480 slices. The results show an improvement in the accuracy and smoothness of the extracted boundaries. The improvement obtained for the accuracy of segmentation is about 6% in comparison to the one achieved by the methods based on thresholding and region growing only. Discussion and Conclusion: The extracted contours using modified GDM are smoother and finer. The improvement achieved in this work on the performance of stopping function of GDM model together with applying two stage segmentation of boundaries have resulted in a great improvement on the computational efficiency of GDM algorithm while making smoother and finer colon borders.

  8. Modified mesenchymal stem cells using miRNA transduction alter lung injury in a bleomycin model.

    Science.gov (United States)

    Huleihel, Luai; Sellares, Jacobo; Cardenes, Nayra; Álvarez, Diana; Faner, Rosa; Sakamoto, Koji; Yu, Guoying; Kapetanaki, Maria G; Kaminski, Naftali; Rojas, Mauricio

    2017-07-01

    Although different preclinical models have demonstrated a favorable role for bone marrow-derived mesenchymal stem cells (B-MSC) in preventing fibrosis, this protective effect is not observed with late administration of these cells, when fibrotic changes are consolidated. We sought to investigate whether the late administration of B-MSCs overexpressing microRNAs (miRNAs) let-7d (antifibrotic) or miR-154 (profibrotic) could alter lung fibrosis in a murine bleomycin model. Using lentiviral vectors, we transduced miRNAs (let-7d or miR-154) or a control sequence into human B-MSCs. Overexpression of let-7d or miR-154 was associated with changes in the mesenchymal properties of B-MSCs and in their cytokine expression. Modified B-MSCs were intravenously administered to mice at day 7 after bleomycin instillation, and the mice were euthanized at day 14 Bleomycin-injured animals that were treated with let-7d cells were found to recover quicker from the initial weight loss compared with the other treatment groups. Interestingly, animals treated with miR-154 cells had the lowest survival rate. Although a slight reduction in collagen mRNA levels was observed in lung tissue from let-7d mice, no significant differences were observed in Ashcroft score and OH-proline. However, the distinctive expression in cytokines and CD45-positive cells in the lung suggests that the differential effects observed in both miRNA mice groups were related to an effect on the immunomodulation function. Our results establish the use of miRNA-modified mesenchymal stem cells as a potential future research in lung fibrosis. Copyright © 2017 the American Physiological Society.

  9. Modified APEX model for Simulating Macropore Phosphorus Contributions to Tile Drains.

    Science.gov (United States)

    Ford, William I; King, Kevin W; Williams, Mark R; Confesor, Remegio B

    2017-11-01

    The contribution of macropore flow to phosphorus (P) loadings in tile-drained agricultural landscapes remains poorly understood at the field scale, despite the recognized deleterious impacts of contaminant transport via macropore pathways. A new subroutine that couples existing matrix-excess and matrix-desiccation macropore flow theory and a modified P routine is implemented in the Agricultural Policy Environmental eXtender (APEX) model. The original and modified formulation were applied and evaluated for a case study in a poorly drained field in Western Ohio with 31 months of surface and subsurface monitoring data. Results highlighted that a macropore subroutine in APEX improved edge-of-field discharge calibration and validation for both tile and total discharge from satisfactory and good, respectively, to very good and improved dissolved reactive P load calibration and validation statistics for tile P loads from unsatisfactory to very good. Output from the calibrated macropore simulations suggested median annual matrix-desiccation macropore flow contributions of 48% and P load contributions of 43%, with the majority of loading occurring in winter and spring. While somewhat counterintuitive, the prominence of matrix-desiccation macropore flow during seasons with less cracking reflects the importance of coupled development of macropore pathways and adequate supply of the macropore flow source. The innovative features of the model allow for assessments of annual macropore P contributions to tile drainage and has the potential to inform P site assessment tools. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  10. Bulk-friction modeling of afterslip and the modified Omori law

    Science.gov (United States)

    Wennerberg, Leif; Sharp, Robert V.

    1997-08-01

    Afterslip data from the Superstition Hills fault in southern California, a creep event on the same fault, the modified Omori law, and cumulative moments from aftershocks of the 1957 Aleutian Islands earthquake all indicate that the original formulation by Dieterich (1981) [Constitutive properties of faults with simulated gouge. AGU, Geophys. Monogr. 24, 103-120] for friction evolution is more appropriate for systems far from instability than the commonly used approximation developed by Ruina (1983) [Slip instability and state variable friction laws. J. Geophys. Res. 88, 10359-10370] to study instability. The mathematical framework we use to test the friction models is a one-dimensional, massless spring-slider under the simplifying assumption, proposed by Scholz (1990) [The Mechanics of Earthquakes and Faulting. Cambridge University Press] and used by Marone et al. (1991) [On the mechanics of earthquake afterslip. J. Geophys. Res., 96: 8441-8452], that the state variable takes on its velocity-dependent steady-state value throughout motion in response to a step in stress. This assumption removes explicit state-variable dependence from the model, obviating the need to consider state-variable evolution equations. Anti-derivatives of the modified Omori law fit our data very well and are very good approximate solutions to our model equations. A plausible friction model with Omori-law solutions used by Wesson (1988) [Dynamics of fault creep. J. Geophys. Res. 93, 8929-8951] to model fault creep and generalized by Rice (1983) [Constitutive relations for fault slip and earthquake instabilities. Pure Appl. Geophys. 121, 443-475] to a rate-and-state variable friction model yields exactly Omori's law with exponents greater than 1, but yields unstable solutions for Omori exponents less than 1. We estimate from the Dieterich formulation the dimensionless parameter a∗ which is equal to the product of the nominal coefficient of friction and the more commonly reported friction

  11. Aspects of solitons in noncommutative field theories. The modified Ward model

    International Nuclear Information System (INIS)

    Petersen, S.

    2006-01-01

    In this thesis several aspects of solutions to the equations of motions to noncommutative field theories are investigated in detail. The main focus of the analysis is on the integrable chiral or modified unitary sigma model with U(n)-valued fields as introduced by Ward and its noncommutative extension where the above mentioned new solutions arise. Of particular interest in this context are to us the question of stability of static solitons and the applicability of the so-called adiabatic approach to as a means to approximate time-dependent solutions by geodesic motion in the moduli space of static solutions. After some introductory remarks we proceed to present the Ward model together with its noncommutative extension and give a unified exposition of its known static solutions. This model, as the prime example of an almost Lorentz-invariant field theory in 1+2 dimensions, has several virtues which make its analysis worthwhile. First of all it is integrable thus allowing for powerful, well developed, techniques to generate soliton solutions. At the same time these feature interaction among them. Furthermore, the commutative counterpart of the Ward model has been investigated in great detail such that many results are available for comparison. Next, the question of stability for the present static solutions is considered. This stability is governed by the quadratic form of the fluctuations, which, upon concentrating on the case of diagonal U(1) solutions, is explicitly computed. We show that the considered solutions are stable within a certain subsector of possible configurations, namely the grassmannian ones, and become unstable upon embedding them into the full unitary sigma model. Finally, we remark on some possible generalization of these results. This subject is followed, after a brief review of time-dependent Ward model solutions, by the application of the adiabatic approach, as proposed by Manton, to the static solutions. (orig.)

  12. Content Validity of a Psychotherapeutic Intervention Model in Nursing: A Modified e-Delphi Study.

    Science.gov (United States)

    Sampaio, Francisco Miguel Correia; Sequeira, Carlos; Lluch Canut, Teresa

    2017-04-01

    To estimate the content validity of a psychotherapeutic intervention model in nursing. Mental health nurses encounter great extrinsic difficulties when it comes to providing psychotherapeutic interventions due to the fact that they are not allowed to perform such practice in some countries. In this light, the pursuit of a psychotherapeutic intervention model in nursing seems germane to guide the professionals' psychotherapeutic practice, contributing hereof to increase mental health nurses' professional autonomy. Modified e-Delphi. Data were collected from October 2015 to January 2016 by means of three rounds of online questionnaires. The initial questionnaire was structured into five sections: general structure of the model, patients' exclusion criteria, assessment framework, nursing diagnoses, and nursing psychotherapeutic interventions. From the 42 experts invited, at least twenty (20) participated in each round. The experts achieved consensus with regard to the conclusion that nursing psychotherapeutic interventions should always seek to address a nursing diagnosis. These defined furthermore that a psychotherapeutic intervention model in nursing should be exercised by means of 3 to 12 sessions using Nursing Interventions Classification (NIC) as a resource. Finally, experts deemed that the model should follow the principles of integrative psychotherapy, so that techniques from different schools of psychotherapy could therefore be used in conjunction to promote the resolution of a nursing diagnosis. Achieving consensus about the structure of a psychotherapeutic intervention model in nursing is imperative to guide nurses in the provision of nursing psychotherapeutic interventions and to enable an effective evaluation of the health gains associated with its implementation. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Numerical simulation of the self-pumped long Josephson junction using a modified sine-Gordon model

    DEFF Research Database (Denmark)

    Sobolev, A.; Pankratov, A.; Mygind, Jesper

    2006-01-01

    We have numerically investigated the dynamics of a long Josephson junction (flux-flow oscillator) biased by a DC current in the presence of magnetic field. The study is performed in the frame of the modified sine-Gordon model, which includes the surface losses, RC-load at both FFO ends and the self-pumping...... effect. In our model the dumping parameter depends both on the spatial coordinate and the amplitude of the AC voltage. In order to find the DC FFO voltage the damping parameter has to be calculated by successive approximations and time integration of the perturbed sine-Gordon equation. The modified model...

  14. A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    El Backly, Rania M. [DIMES, University of Genova, Genova (Italy); IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Chiapale, Danilo [IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Muraglia, Anita [Biorigen S.R.L., Genova (Italy); Tromba, Giuliana [Sincrotrone Trieste S.C.P.A., Trieste (Italy); Ottonello, Chiara [Biorigen S.R.L., Genova (Italy); Santolini, Federico [IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Cancedda, Ranieri; Mastrogiacomo, Maddalena, E-mail: maddalena.mastrogiacomo@unige.it [DIMES, University of Genova, Genova (Italy); IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy)

    2015-01-06

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX{sup ®}) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12–16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX{sup ®}) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.

  15. A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

    International Nuclear Information System (INIS)

    El Backly, Rania M.; Chiapale, Danilo; Muraglia, Anita; Tromba, Giuliana; Ottonello, Chiara; Santolini, Federico; Cancedda, Ranieri; Mastrogiacomo, Maddalena

    2015-01-01

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX ® ) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12–16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX ® ) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.

  16. Organic Pollutant Penetration through Fruit Polyester Skin: A Modified Three-compartment Diffusion Model.

    Science.gov (United States)

    Li, Yungui; Li, Qingqing; Chen, Baoliang

    2016-03-24

    The surface of plants is covered by a continuous but heterogeneous cuticular membrane (CM). Serving as the first protective barrier, the uptake and transport behavior of organic pollutants at this interface continue to engage the research efforts of environmental chemist. To date, the contributions of cuticular components as a defense against the organic pollutants penetration remain unresolved. In this study, the unsteady-state penetration characteristics of phenanthrene (PHE) through isolated fruit CM was investigated. PHE penetration was differentiated by three cuticular compartments: epicuticular waxes (EW), cuticle proper (CP) and cuticular layer (CL). The driving force for PHE penetration was ascribed to the sharp concentration gradient built up endogenously by cuticular compartments with different lipophilic affinities. A modified penetration model was established and verified in terms of its general suitability for the hydrophobic chemicals and CMs of various plant species (apple, tomato and potato). The new three-compartment model demonstrates much higher accuracy in characterizing the uptake and transport behavior of semivolatile chemicals with fewer limitations in terms of environmental conditions and complexity (e.g., coexisting contaminants and temperature). This model could contribute to a more comprehensive understanding on the role of polymeric lipids in the organic pollutant sorption and transport into plants.

  17. A modified atmospheric non-hydrostatic model on low aspect ratio grids: part II

    Directory of Open Access Journals (Sweden)

    Wen-Yih Sun

    2013-06-01

    Full Text Available Sun et al. (2012 proposed a modified non-hydrostatic model (MNH, in which the left-hand side of the continuity equation is multiplied by a parameter δ (4≤δ≤16 in the article to suppress high-frequency acoustic waves. They showed that the MNH allows a longer time step than the original non-hydrostatic model (NH. The MNH is also more accurate and efficient than the horizontal explicit and vertical implicit scheme (HE–VI when the aspect ratio (Δx/Δz is small. In addition to multiplying a parameter δ, here we propose to add a smoothing on the right-hand side of the continuity equation in the MNH to damp shortest sound waves. Linear stability analysis and non-linear model simulations show that the MNH with smoothing (henceforth abbreviated as MNHS can use twice the time interval of the MNH while maintaining the same accuracy. The MNHS is also more accurate and efficient than HE–VI when the aspect ratio is small.

  18. Comparison of application of various crossovers in solving inhomogeneous minimax problem modified by Goldberg model

    Science.gov (United States)

    Kobak, B. V.; Zhukovskiy, A. G.; Kuzin, A. P.

    2018-05-01

    This paper considers one of the classical NP complete problems - an inhomogeneous minimax problem. When solving such large-scale problem, there appear difficulties in obtaining an exact solution. Therefore, let us propose getting an optimum solution in an acceptable time. Among a wide range of genetic algorithm models, let us choose the modified Goldberg model, which earlier was successfully used by authors in solving NP complete problems. The classical Goldberg model uses a single-point crossover and a singlepoint mutation, which somewhat decreases the accuracy of the obtained results. In the article, let us propose using a full two-point crossover with various mutations previously researched. In addition, the work studied the necessary probability to apply it to the crossover in order to obtain results that are more accurate. Results of the computation experiment showed that the higher the probability of a crossover, the higher the quality of both the average results and the best solutions. In addition, it was found out that the higher the values of the number of individuals and the number of repetitions, the closer both the average results and the best solutions to the optimum. The paper shows how the use of a full two-point crossover increases the accuracy of solving an inhomogeneous minimax problem, while the time for getting the solution increases, but remains polynomial.

  19. Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

    International Nuclear Information System (INIS)

    Stroev, N E; Iosilevskiy, I L

    2016-01-01

    Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state of electronic and ionic subsystems were used in present calculations within the Gibbs-Guggenheim conditions of non-congruent phase equilibrium. Parameters of critical point-line were calculated on the entire range of proportions of mixed ions 0 < X < 1. Strong “distillation” effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications. (paper)

  20. Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

    Science.gov (United States)

    Stroev, N. E.; Iosilevskiy, I. L.

    2016-11-01

    Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state of electronic and ionic subsystems were used in present calculations within the Gibbs-Guggenheim conditions of non-congruent phase equilibrium. Parameters of critical point-line were calculated on the entire range of proportions of mixed ions 0 distillation” effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications.

  1. Prediction of phosphorus loads in an artificially drained lowland catchment using a modified SWAT model

    Science.gov (United States)

    Bauwe, Andreas; Eckhardt, Kai-Uwe; Lennartz, Bernd

    2017-04-01

    Eutrophication is still one of the main environmental problems in the Baltic Sea. Currently, agricultural diffuse sources constitute the major portion of phosphorus (P) fluxes to the Baltic Sea and have to be reduced to achieve the HELCOM targets and improve the ecological status. Eco-hydrological models are suitable tools to identify sources of nutrients and possible measures aiming at reducing nutrient loads into surface waters. In this study, the Soil and Water Assessment Tool (SWAT) was applied to the Warnow river basin (3300 km2), the second largest watershed in Germany discharging into the Baltic Sea. The Warnow river basin is located in northeastern Germany and characterized by lowlands with a high proportion of artificially drained areas. The aim of this study were (i) to estimate P loadings for individual flow fractions (point sources, surface runoff, tile flow, groundwater flow), spatially distributed on sub-basin scale. Since the official version of SWAT does not allow for the modeling of P in tile drains, we tested (ii) two different approaches of simulating P in tile drains by changing the SWAT source code. The SWAT source code was modified so that (i) the soluble P concentration of the groundwater was transferred to the tile water and (ii) the soluble P in the soil was transferred to the tiles. The SWAT model was first calibrated (2002-2011) and validated (1992-2001) for stream flow at 7 headwater catchments at a daily time scale. Based on this, the stream flow at the outlet of the Warnow river basin was simulated. Performance statistics indicated at least satisfactory model results for each sub-basin. Breaking down the discharge into flow constituents, it becomes visible that stream flow is mainly governed by groundwater and tile flow. Due to the topographic situation with gentle slopes, surface runoff played only a minor role. Results further indicate that the prediction of soluble P loads was improved by the modified SWAT versions. Major sources of

  2. Bulk-friction modeling of afterslip and the modified Omori law

    Science.gov (United States)

    Wennerberg, Leif; Sharp, Robert V.

    1997-01-01

    Afterslip data from the Superstition Hills fault in southern California, a creep event on the same fault, the modified Omori law, and cumulative moments from aftershocks of the 1957 Aleutian Islands earthquake all indicate that the original formulation by Dieterich (1981) [Constitutive properties of faults with simulated gouge. AGU, Geophys. Monogr. 24, 103–120] for friction evolution is more appropriate for systems far from instability than the commonly used approximation developed by Ruina (1983) [Slip instability and state variable friction laws. J. Geophys. Res. 88, 10359–10370] to study instability. The mathematical framework we use to test the friction models is a one-dimensional, massless spring-slider under the simplifying assumption, proposed by Scholz (1990) [The Mechanics of Earthquakes and Faulting. Cambridge University Press] and used by Marone et al. (1991) [On the mechanics of earthquake afterslip. J. Geophys. Res., 96: 8441–8452], that the state variable takes on its velocity-dependent steady-state value throughout motion in response to a step in stress. This assumption removes explicit state-variable dependence from the model, obviating the need to consider state-variable evolution equations. Anti-derivatives of the modified Omori law fit our data very well and are very good approximate solutions to our model equations. A plausible friction model with Omori-law solutions used by Wesson (1988) [Dynamics of fault creep. J. Geophys. Res. 93, 8929–8951] to model fault creep and generalized by Rice (1983) [Constitutive relations for fault slip and earthquake instabilities. Pure Appl. Geophys. 121, 443–475] to a rate-and-state variable friction model yields exactly Omori's law with exponents greater than 1, but yields unstable solutions for Omori exponents less than 1. We estimate from the Dieterich formulation the dimensionless parameter a∗ which is equal to the product of the nominal coefficient of friction and the more commonly reported

  3. Self-organized Criticality in a Modified Evolution Model on Generalized Barabasi-Albert Scale-Free Networks

    International Nuclear Information System (INIS)

    Lin Min; Wang Gang; Chen Tianlun

    2007-01-01

    A modified evolution model of self-organized criticality on generalized Barabasi-Albert (GBA) scale-free networks is investigated. In our model, we find that spatial and temporal correlations exhibit critical behaviors. More importantly, these critical behaviors change with the parameter b, which weights the distance in comparison with the degree in the GBA network evolution.

  4. Variance Components Models for Physical Activity With Age as Modifier: A Comparative Twin Study in Seven Countries

    NARCIS (Netherlands)

    Vink, J.M.; Boomsma, D.I.; Medland, S.E.; Moor, H.M. de; Stubbe, J.H.; Corner, B.K.; Martin, N.G.; Skytthea, A.; Kyvik, K.O.; Rose, R..J.; Kujala, U.M.; Kaprio, J.; Harris, J.R.; Pedersen, N.L.; Cherkas, L.; Spector, T.D.; Geus, E.J.

    2011-01-01

    Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self-reported

  5. Dynamics Under Location Uncertainty: Model Derivation, Modified Transport and Uncertainty Quantification

    Science.gov (United States)

    Resseguier, V.; Memin, E.; Chapron, B.; Fox-Kemper, B.

    2017-12-01

    In order to better observe and predict geophysical flows, ensemble-based data assimilation methods are of high importance. In such methods, an ensemble of random realizations represents the variety of the simulated flow's likely behaviors. For this purpose, randomness needs to be introduced in a suitable way and physically-based stochastic subgrid parametrizations are promising paths. This talk will propose a new kind of such a parametrization referred to as modeling under location uncertainty. The fluid velocity is decomposed into a resolved large-scale component and an aliased small-scale one. The first component is possibly random but time-correlated whereas the second is white-in-time but spatially-correlated and possibly inhomogeneous and anisotropic. With such a velocity, the material derivative of any - possibly active - tracer is modified. Three new terms appear: a correction of the large-scale advection, a multiplicative noise and a possibly heterogeneous and anisotropic diffusion. This parameterization naturally ensures attractive properties such as energy conservation for each realization. Additionally, this stochastic material derivative and the associated Reynolds' transport theorem offer a systematic method to derive stochastic models. In particular, we will discuss the consequences of the Quasi-Geostrophic assumptions in our framework. Depending on the turbulence amount, different models with different physical behaviors are obtained. Under strong turbulence assumptions, a simplified diagnosis of frontolysis and frontogenesis at the surface of the ocean is possible in this framework. A Surface Quasi-Geostrophic (SQG) model with a weaker noise influence has also been simulated. A single realization better represents small scales than a deterministic SQG model at the same resolution. Moreover, an ensemble accurately predicts extreme events, bifurcations as well as the amplitudes and the positions of the simulation errors. Figure 1 highlights this last

  6. Using a modified technology acceptance model to evaluate healthcare professionals' adoption of a new telemonitoring system.

    Science.gov (United States)

    Gagnon, Marie Pierre; Orruño, Estibalitz; Asua, José; Abdeljelil, Anis Ben; Emparanza, José

    2012-01-01

    To examine the factors that could influence the decision of healthcare professionals to use a telemonitoring system. A questionnaire, based on the Technology Acceptance Model (TAM), was developed. A panel of experts in technology assessment evaluated the face and content validity of the instrument. Two hundred and thirty-four questionnaires were distributed among nurses and doctors of the cardiology, pulmonology, and internal medicine departments of a tertiary hospital. Cronbach alpha was calculated to measure the internal consistency of the questionnaire items. Construct validity was evaluated using interitem correlation analysis. Logistic regression analysis was performed to test the theoretical model. Adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were computed. A response rate of 39.7% was achieved. With the exception of one theoretical construct (Habit) that corresponds to behaviors that become automatized, Cronbach alpha values were acceptably high for the remaining constructs. Theoretical variables were well correlated with each other and with the dependent variable. The original TAM was good at predicting telemonitoring usage intention, Perceived Usefulness being the only significant predictor (OR: 5.28, 95% CI: 2.12-13.11). The model was still significant and more powerful when the other theoretical variables were added. However, the only significant predictor in the modified model was Facilitators (OR: 4.96, 95% CI: 1.59-15.55). The TAM is a good predictive model of healthcare professionals' intention to use telemonitoring. However, the perception of facilitators is the most important variable to consider for increasing doctors' and nurses' intention to use the new technology.

  7. Genome-wide association study to identify potential genetic modifiers in a canine model for Duchenne muscular dystrophy.

    Science.gov (United States)

    Brinkmeyer-Langford, Candice; Balog-Alvarez, Cynthia; Cai, James J; Davis, Brian W; Kornegay, Joe N

    2016-08-22

    Duchenne muscular dystrophy (DMD) causes progressive muscle degeneration, cardiomyopathy and respiratory failure in approximately 1/5,000 boys. Golden Retriever muscular dystrophy (GRMD) resembles DMD both clinically and pathologically. Like DMD, GRMD exhibits remarkable phenotypic variation among affected dogs, suggesting the influence of modifiers. Understanding the role(s) of genetic modifiers of GRMD may identify genes and pathways that also modify phenotypes in DMD and reveal novel therapies. Therefore, our objective in this study was to identify genetic modifiers that affect discrete GRMD phenotypes. We performed a linear mixed-model (LMM) analysis using 16 variably-affected dogs from our GRMD colony (8 dystrophic, 8 non-dystrophic). All of these dogs were either full or half-siblings, and phenotyped for 19 objective, quantitative biomarkers at ages 6 and 12 months. Each biomarker was individually assessed. Gene expression profiles of 59 possible candidate genes were generated for two muscle types: the cranial tibialis and medial head of the gastrocnemius. SNPs significantly associated with GRMD biomarkers were identified on multiple chromosomes (including the X chromosome). Gene expression levels for candidate genes located near these SNPs correlated with biomarker values, suggesting possible roles as GRMD modifiers. The results of this study enhance our understanding of GRMD pathology and represent a first step toward the characterization of GRMD modifiers that may be relevant to DMD pathology. Such modifiers are likely to be useful for DMD treatment development based on their relationships to GRMD phenotypes.

  8. Genetic and chemical modifiers of a CUG toxicity model in Drosophila.

    Directory of Open Access Journals (Sweden)

    Amparo Garcia-Lopez

    2008-02-01

    Full Text Available Non-coding CUG repeat expansions interfere with the activity of human Muscleblind-like (MBNL proteins contributing to myotonic dystrophy 1 (DM1. To understand this toxic RNA gain-of-function mechanism we developed a Drosophila model expressing 60 pure and 480 interrupted CUG repeats in the context of a non-translatable RNA. These flies reproduced aspects of the DM1 pathology, most notably nuclear accumulation of CUG transcripts, muscle degeneration, splicing misregulation, and diminished Muscleblind function in vivo. Reduced Muscleblind activity was evident from the sensitivity of CUG-induced phenotypes to a decrease in muscleblind genetic dosage and rescue by MBNL1 expression, and further supported by the co-localization of Muscleblind and CUG repeat RNA in ribonuclear foci. Targeted expression of CUG repeats to the developing eye and brain mushroom bodies was toxic leading to rough eyes and semilethality, respectively. These phenotypes were utilized to identify genetic and chemical modifiers of the CUG-induced toxicity. 15 genetic modifiers of the rough eye phenotype were isolated. These genes identify putative cellular processes unknown to be altered by CUG repeat RNA, and they include mRNA export factor Aly, apoptosis inhibitor Thread, chromatin remodelling factor Nurf-38, and extracellular matrix structural component Viking. Ten chemical compounds suppressed the semilethal phenotype. These compounds significantly improved viability of CUG expressing flies and included non-steroidal anti-inflammatory agents (ketoprofen, muscarinic, cholinergic and histamine receptor inhibitors (orphenadrine, and drugs that can affect sodium and calcium metabolism such as clenbuterol and spironolactone. These findings provide new insights into the DM1 phenotype, and suggest novel candidates for DM1 treatments.

  9. Evaluation of right heart function in a rat model using modified echocardiographic views.

    Science.gov (United States)

    Bernardo, Ivan; Wong, James; Wlodek, Mary E; Vlahos, Ross; Soeding, Paul

    2017-01-01

    Echocardiography plays a major role in assessing cardiac function in animal models. We investigated use of a modified parasternal mid right-ventricular (MRV) and right ventricle (RV) outflow (RVOT) view, in assessing RV size and function, and the suitability of advanced 2D-strain analysis. 15 WKY rats were examined using transthoracic echocardiography. The left heart was assessed using standard short and long axis views. For the right ventricle a MRV and RVOT view were used to measure RV chamber and free wall area. 2D-strain analysis was applied to both ventricles using off-line analysis. RV chamber volume was determined by injection of 2% agarose gel, and RV free wall dissected and weighed. Echocardiography measurement was correlated with necropsy findings. The RV mid-ventricular dimension (R1) was 0.42±0.07cm and the right ventricular outflow tract dimension (R2) was 0.34±0.06cm, chamber end-diastolic area measurements were 0.38±0.09cm2 and 0.29±0.08cm2 for MRV and RVOT views respectively. RVOT and MRV chamber area correlated with gel mass. Doppler RV stroke volume was 0.32±0.08ml, cardiac output (CO) 110±27 ml.min-1 and RV free wall contractility assessed using 2D-strain analysis was demonstrated. We have shown that modified MRV and RVOT views can provide detailed assessment of the RV in rodents, with 2D-strain analysis of the RV free wall potentially feasible.

  10. Additional disinfection with a modified salt solution in a root canal model.

    Science.gov (United States)

    van der Waal, Suzette V; Oonk, Charlotte A M; Nieman, Selma H; Wesselink, Paul R; de Soet, Johannes J; Crielaard, Wim

    2015-10-01

    The aim of this study is to investigate the disinfecting properties of a modified salt solution (MSS) and calcium hydroxide (Ca(OH)2) in a non-direct-contact ex-vivo model. Seventy-four single-canal roots infected with Enterococcus faecalis were treated with 1% sodium hypochlorite (NaOCl) irrigation or with NaOCl irrigation with subsequent dressing with MSS or Ca(OH)2. After removal of the dressings, the roots were filled with bacterial growth medium and incubated for seven days to enable the surviving bacteria to repopulate the root canal lumen. Growth was determined by sampling the root canals with paper points before treatment (S1), after treatment (S2) and incubation after treatment (S3). The colony forming units were counted at S1 and S2. At S3, growth was determined as no/yes regrowth. The Kruskal-Wallis, McNemar and χ(2) test were used for statistical analyses. At S2, in the NaOCl group, growth was found in 5 of 19 root canals. After the removal of MSS or Ca(OH)2 bacteria were retrieved from one root canal in both groups. At S3, repopulation of the root canals had occurred in 14 of 19 roots after sole NaOCl irrigation, 6 of 20 roots after MSS-dressing and in 14 of 20 roots after Ca(OH)2-dressing. MSS was more effective in preventing regrowth than Ca(OH)2 (P=0.009). The modified salt solution prevented regrowth in roots which indicates that it can eliminate persistent bacteria. Dressing the root canals with Ca(OH)2 did not provide additional disinfection after NaOCl irrigation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Comparison of QuadrapolarTM radiofrequency lesions produced by standard versus modified technique: an experimental model

    Directory of Open Access Journals (Sweden)

    Safakish R

    2017-06-01

    Full Text Available Ramin Safakish Allevio Pain Management Clinic, Toronto, ON, Canada Abstract: Lower back pain (LBP is a global public health issue and is associated with substantial financial costs and loss of quality of life. Over the years, different literature has provided different statistics regarding the causes of the back pain. The following statistic is the closest estimation regarding our patient population. The sacroiliac (SI joint pain is responsible for LBP in 18%–30% of individuals with LBP. Quadrapolar™ radiofrequency ablation, which involves ablation of the nerves of the SI joint using heat, is a commonly used treatment for SI joint pain. However, the standard Quadrapolar radiofrequency procedure is not always effective at ablating all the sensory nerves that cause the pain in the SI joint. One of the major limitations of the standard Quadrapolar radiofrequency procedure is that it produces small lesions of ~4 mm in diameter. Smaller lesions increase the likelihood of failure to ablate all nociceptive input. In this study, we compare the standard Quadrapolar radiofrequency ablation technique to a modified Quadrapolar ablation technique that has produced improved patient outcomes in our clinic. The methodology of the two techniques are compared. In addition, we compare results from an experimental model comparing the lesion sizes produced by the two techniques. Taken together, the findings from this study suggest that the modified Quadrapolar technique provides longer lasting relief for the back pain that is caused by SI joint dysfunction. A randomized controlled clinical trial is the next step required to quantify the difference in symptom relief and quality of life produced by the two techniques. Keywords: lower back pain, radiofrequency ablation, sacroiliac joint, Quadrapolar radiofrequency ablation

  12. Modified Exponential (MOE) Models: statistical Models for Risk Estimation of Low dose Rate Radiation

    International Nuclear Information System (INIS)

    Ogata, H.; Furukawa, C.; Kawakami, Y.; Magae, J.

    2004-01-01

    Simultaneous inclusion of dose and dose-rate is required to evaluate the risk of long term irradiation at low dose-rates, since biological responses to radiation are complex processes that depend both on irradiation time and total dose. Consequently, it is necessary to consider a model including cumulative dose,dose-rate and irradiation time to estimate quantitative dose-response relationship on the biological response to radiation. In this study, we measured micronucleus formation and (3H) thymidine uptake in U2OS, human osteosarcoma cell line, as indicators of biological response to gamma radiation. Cells were exposed to gamma ray in irradiation room bearing 50,000 Ci 60Co. After irradiation, they were cultured for 24h in the presence of cytochalasin B to block cytokinesis, and cytoplasm and nucleus were stained with DAPI and propidium iodide. The number of binuclear cells bearing a micronucleus was counted under a florescence microscope. For proliferation inhibition, cells were cultured for 48 h after the irradiation and (3h) thymidine was pulsed for 4h before harvesting. We statistically analyzed the data for quantitative evaluation of radiation risk at low dose/dose-rate. (Author)

  13. Overland flow connectivity on planar patchy hillslopes - modified percolation theory approaches and combinatorial model of urns

    Science.gov (United States)

    Nezlobin, David; Pariente, Sarah; Lavee, Hanoch; Sachs, Eyal

    2017-04-01

    Source-sink systems are very common in hydrology; in particular, some land cover types often generate runoff (e.g. embedded rocks, bare soil) , while other obstruct it (e.g. vegetation, cracked soil). Surface runoff coefficients of patchy slopes/plots covered by runoff generating and obstructing covers (e.g., bare soil and vegetation) depend critically on the percentage cover (i.e. sources/sinks abundance) and decrease strongly with observation scale. The classic mathematical percolation theory provides a powerful apparatus for describing the runoff connectivity on patchy hillslopes, but it ignores strong effect of the overland flow directionality. To overcome this and other difficulties, modified percolation theory approaches can be considered, such as straight percolation (for the planar slopes), quasi-straight percolation and models with limited obstruction. These approaches may explain both the observed critical dependence of runoff coefficients on percentage cover and their scale decrease in systems with strong flow directionality (e.g. planar slopes). The contributing area increases sharply when the runoff generating percentage cover approaches the straight percolation threshold. This explains the strong increase of the surface runoff and erosion for relatively low values (normally less than 35%) of the obstructing cover (e.g., vegetation). Combinatorial models of urns with restricted occupancy can be applied for the analytic evaluation of meaningful straight percolation quantities, such as NOGA's (Non-Obstructed Generating Area) expected value and straight percolation probability. It is shown that the nature of the cover-related runoff scale decrease is combinatorial - the probability for the generated runoff to avoid obstruction in unit area decreases with scale for the non-trivial percentage cover values. The magnitude of the scale effect is found to be a skewed non-monotonous function of the percentage cover. It is shown that the cover-related scale

  14. A Modified Model Reference Adaptive Control for a Single Motor of Latch Type Control Element Drive Mechanism

    International Nuclear Information System (INIS)

    Park, Bae Jeong

    2016-01-01

    A modified Model Reference Adaptive Control (MRAC) for a single motor of latch type Control Element Drive Mechanism (CEDM) is described herein. The CEDM has complicated dynamic characteristics including electrical, mechanical, and magnetic effects. The previous control system has utilized a Proportional-Integral (PI) controller, and the control performance is limited according to nonlinear dynamic characteristics and environmental conditions. The modified MRAC using system identification (ID) technique improves the control performance in the operating condition such as model parameter variation and environmental condition change. The modified MRAC using the identified reference model with feed-forward gain and 180Hz noise reduction filter presents better performance under normal and/or abnormal condition. The simplified reference model can make H/W implementation more practical on the viewpoint of less computation and good performance. Actually, the CEDM controller shall be capable of controlling 101 control element assemblies (CEAs) individually in the nuclear power plant. Because the load conditions and the environmental condition around the 101 CEAs are all different minutely, the proposed modified MRAC can be a good practice. The modified MRAC controller will be applied in the real nuclear power plant later and this will overcome some weak point of PI controller

  15. Optimization of parameters for fitting linear accelerator photon beams using a modified CBEAM model

    International Nuclear Information System (INIS)

    Ayyangar, K.; Daftari, I.; Palta, J.; Suntharalingam, N.

    1989-01-01

    Measured beam profiles and central-axis depth-dose data for 6- and 25-MV photon beams are used to generate a dose matrix which represents the full beam. A corresponding dose matrix is also calculated using the modified CBEAM model. The calculational model uses the usual set of three parameters to define the intensity at beam edges and the parameter that accounts for collimator transmission. An additional set of three parameters is used for the primary profile factor, expressed as a function of distance from the central axis. An optimization program has been adapted to automatically adjust these parameters to minimize the χ 2 between the measured and calculated data. The average values of the parameters for small (6x6 cm 2 ), medium (10x10 cm 2 ), and large (20x20 cm 2 ) field sizes are found to represent the beam adequately for all field sizes. The calculated and the measured doses at any point agree to within 2% for any field size in the range 4x4 to 40x40 cm 2

  16. QUALITY OF HIGHER EDUCATION IN BANGLADESH: APPLICATION OF A MODIFIED SERVQUAL MODEL

    Directory of Open Access Journals (Sweden)

    Md. Mamun-ur-Rashid

    2017-02-01

    Full Text Available Progressive importance, swelling investment, and mounting national and global competition necessitate evaluation of the service quality of higher education. Quantifiable indicators such as student teacher ratio, student number, women participation, establishing new departments, and increase in the number of universities are no longer enough unless the student’s stand point is considered. This research probed the service quality of higher education in a public university in southern Bangladesh utilizing modified SERVQUAL gap model. The t-test results suggest that there is a significant service gap in all the selected service dimensions such as learning, teaching, recognition, assessment system, internet and library facilities, campus life, and non-academic administration. The results also mirror that little more than half (54.1% students are satisfied with the service quality of the selected university and almost similar proportion (52.1 % of the students have future interest in studying in the same university. Regression analysis reveals that learning and recognition are two important determinants of client’s overall satisfaction with the service of selected university. Importance Performance Analysis (IPA advocates that the university should take immediate step in improving internet and library facilities, campus life, and non-academic administration. Factor analysis output confirms that slight modification of the proposed seven set model into six set factors can be employed by the management as off-the-rack service quality measurement tool.

  17. A modified atmospheric non-hydrostatic model on low aspect ratio grids

    Directory of Open Access Journals (Sweden)

    Wen-Yih Sun

    2012-04-01

    Full Text Available It is popular to use a horizontal explicit and a vertical implicit (HE-VI scheme in the compressible non-hydrostatic (NH model. However, when the aspect ratio becomes small, a small time-interval is required in HE-VI, because the Courant-Fredrich-Lewy (CFL criterion is determined by the horizontal grid spacing. Furthermore, simulations from HE-VI can depart from the forward–backward (FB scheme in NH even when the time interval is less than the CFL criterion allowed. Hence, a modified non-hydrostatic (MNH model is proposed, in which the left-hand side of the continuity equation is multiplied by a parameter δ (4≤δ≤16, in this study. When the linearized MNH is solved by FB (can be other schemes, the eigenvalue shows that MNH can suppress the frequency of acoustic waves very effectively but does not have a significant impact on the gravity waves. Hence, MNH enables to use a longer time step than that allowed in the original NH. When the aspect ratio is small, MNH solved by FB can be more accurate and efficient than the NH solved by HE-VI. Therefore, MNH can be very useful to study cloud, Large Eddy Simulation (LES, turbulence, flow over complex terrains, etc., which require fine resolution in both horizontal and vertical directions.

  18. Super-cool paints: optimizing composition with a modified four-flux model

    Science.gov (United States)

    Gali, Marc A.; Arnold, Matthew D.; Gentle, Angus R.; Smith, Geoffrey B.

    2017-09-01

    The scope for maximizing the albedo of a painted surface to produce low cost new and retro-fitted super-cool roofing is explored systematically. The aim is easy to apply, low cost paint formulations yielding albedos in the range 0.90 to 0.95. This requires raising the near-infrared (NIR) spectral reflectance into this range, while not reducing the more easily obtained high visible reflectance values. Our modified version of the four-flux method has enabled results on more complex composites. Key parameters to be optimized include; fill factors, particle size and material, using more than one mean size, thickness, substrate and binder materials. The model used is a variation of the classical four-flux method that solves the energy transfer problem through four balance differential equations. We use a different approach to the characteristic parameters to define the absorptance and scattering of the complete composite. This generalization allows extension to inclusion of size dispersion of the pigment particle and various binder resins, including those most commonly in use based on acrylics. Thus, the pigment scattering model has to take account of the matrix having loss in the NIR. A paint ranking index aimed specifically at separating paints with albedo above 0.80 is introduced representing the fraction of time at a sub-ambient temperature.

  19. Plants may alter competition by modifying nutrient bioavailability in rhizosphere: a modeling approach.

    Science.gov (United States)

    Raynaud, Xavier; Jaillard, Benoît; Leadley, Paul W

    2008-01-01

    Plants modify nutrient availability by releasing chemicals in the rhizosphere. This change in availability induced by roots (bioavailability) is known to improve nutrient uptake by individual plants releasing such compounds. Can this bioavailability alter plant competition for nutrients and under what conditions? To address these questions, we have developed a model of nutrient competition between plant species based on mechanistic descriptions of nutrient diffusion, plant exudation, and plant uptake. The model was parameterized using data of the effects of root citrate exudation on phosphorus availability. We performed a sensitivity analysis for key parameters to test the generality of these effects. Our simulations suggest the following. (1) Nutrient uptake depends on the number of roots when nutrients and exudates diffuse little, because individual roots are nearly independent in terms of nutrient supply. In this case, bioavailability profits only species with exudates. (2) Competition for nutrients depends on the spatial arrangement of roots when nutrients diffuse little but exudates diffuse widely. (3) Competition for nutrients depends on the nutrient uptake capacity of roots when nutrients and exudates diffuse widely. In this case, bioavailability profits all species. Mechanisms controlling competition for bioavailable nutrients appear to be diverse and strongly depend on soil, nutrient, and plant properties.

  20. A Modified Model to Estimate Building Rental Multipiers Accounting for Advalorem Operating Expenses

    Directory of Open Access Journals (Sweden)

    Smolyak S.A.

    2016-09-01

    Full Text Available To develop ideas on building element valuation contained in the first article on the subject published in REMV, we propose an elaboration of the approach accounting for ad valorem expenses incidental to property management, such as land taxes, income/capital gains tax, and insurance premium costs; all such costs, being of an ad valorem nature in the first instance, cause circularity in the logic of the model, which, however, is not intractable under the proposed approach. The resulting formulas for carrying out practical estimation of building rental multipliers and, in consequence, of building values, turn out to be somewhat modified, and we demonstrate the sensitivity of the developed approach to the impact of these ad valorem factors. On the other hand, it is demonstrated that (accounting for building depreciation charges, which should seemingly be included among the considered ad valorem factors, cancel out and do not have any impact on the resulting estimates. However, treating the depreciation of buildings in quantifiable economic terms as a reduction in derivable operating benefits over time (instead of mere physical indications, such as age, we also demonstrate that the approach has implications for estimating the economic service lives of buildings and can be practical when used in conjunction with the market-related approach to valuation – from which the requisite model inputs can be extracted as shown in the final part of the paper.

  1. Operational forecasting based on a modified Weather Research and Forecasting model

    Energy Technology Data Exchange (ETDEWEB)

    Lundquist, J; Glascoe, L; Obrecht, J

    2010-03-18

    Accurate short-term forecasts of wind resources are required for efficient wind farm operation and ultimately for the integration of large amounts of wind-generated power into electrical grids. Siemens Energy Inc. and Lawrence Livermore National Laboratory, with the University of Colorado at Boulder, are collaborating on the design of an operational forecasting system for large wind farms. The basis of the system is the numerical weather prediction tool, the Weather Research and Forecasting (WRF) model; large-eddy simulations and data assimilation approaches are used to refine and tailor the forecasting system. Representation of the atmospheric boundary layer is modified, based on high-resolution large-eddy simulations of the atmospheric boundary. These large-eddy simulations incorporate wake effects from upwind turbines on downwind turbines as well as represent complex atmospheric variability due to complex terrain and surface features as well as atmospheric stability. Real-time hub-height wind speed and other meteorological data streams from existing wind farms are incorporated into the modeling system to enable uncertainty quantification through probabilistic forecasts. A companion investigation has identified optimal boundary-layer physics options for low-level forecasts in complex terrain, toward employing decadal WRF simulations to anticipate large-scale changes in wind resource availability due to global climate change.

  2. A modified model of axial flux permanent magnet generator for wind turbine applications

    International Nuclear Information System (INIS)

    Ashraf, M.M.

    2014-01-01

    The Axial Flux Permanent Magnet Generators (AFPMGs) are gaining immense attention in the modern era. The single stage AFPMG topology consists of one stator disc which is held stationery between two revolving rotor discs attached with a common shaft. The number of poles of AFPMG depends on the winding pattern in which the coils are connected in series within stator disc. Connecting the coils in begin-to-end winding pattern, doubles the number of poles which also increases the active mass of AFPMG. The AFPMG considering begin-to-end winding pattern, can be operated at half shaft speed. This AFPMG is also having greater air gap flux density which, ultimately, improves the power density parameter of AFPMG. In this paper, a modified AFPMG has been proposed which is designed by considering begin-to-end winding pattern. A 380W single phase, single stage prototype model has been developed and tested. The test results show that power density of designed AFPMG with begin-to-end winding pattern has been improved by 32% as compared to AFPMG with begin-to-begin winding pattern. The proposed low speed and high power density AFPMG model can be actively deployed for wind turbine applications. (author)

  3. Friedmann model with viscous cosmology in modified f(R,T) gravity theory

    Energy Technology Data Exchange (ETDEWEB)

    Singh, C.P.; Kumar, Pankaj [Delhi Technological University, Department of Applied Mathematics, Delhi (India)

    2014-10-15

    In this paper, we introduce the bulk viscosity in the formalism of modified gravity theory in which the gravitational action contains a general function f(R,T), where R and T denote the curvature scalar and the trace of the energy.momentum tensor, respectively, within the framework of a flat Friedmann-Robertson-Walker model. As an equation of state for a prefect fluid, we take p = (γ - 1)ρ, where 0 ≤ γ ≤ 2 and a viscous term as a bulk viscosity due to the isotropic model, of the form ξ = ξ{sub 0} + ξ{sub 1}H, where ξ{sub 0} and ξ{sub 1} are constants, and H is the Hubble parameter. The exact non-singular solutions to the corresponding field equations are obtained with non-viscous and viscous fluids, respectively, by assuming a simplest particular model of the form of f(R,T) = R + 2f(T), where f(T) = αT (α is a constant). A big-rip singularity is also observed for γ < 0 at a finite value of cosmic time under certain constraints. We study all possible scenarios with the possible positive and negative ranges of α to analyze the expansion history of the universe. It is observed that the universe accelerates or exhibits a transition from a decelerated phase to an accelerated phase under certain constraints of ξ{sub 0} and ξ{sub 1}. We compare the viscous models with the non-viscous one through the graph plotted between the scale factor and cosmic time and find that the bulk viscosity plays a major role in the expansion of the universe. A similar graph is plotted for the deceleration parameter with non-viscous and viscous fluids and we find a transition from decelerated to accelerated phase with some form of bulk viscosity. (orig.)

  4. Regionalization of the Modified Bartlett-Lewis Rectangular Pulse Stochastic Rainfall Model

    Directory of Open Access Journals (Sweden)

    Dongkyun Kim

    2013-01-01

    Full Text Available Parameters of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP stochastic rainfall simulation model were regionalized across the contiguous United States. Three thousand four hundred forty-four National Climate Data Center (NCDC rain gauges were used to obtain spatial and seasonal patterns of the model parameters. The MBLRP model was calibrated to minimize the discrepancy between the precipitation depth statistics between the observed and MBLRP-generated precipitation time series. These statistics included the mean, variance, probability of zero rainfall and autocorrelation at 1-, 3-, 12- and 24-hour accumulation intervals. The Ordinary Kriging interpolation technique was used to generate maps of the six MBLRP model parameters for each of the 12 months of the year. All parameters had clear to discernible regional tendencies; except for one related to rain cell duration distribution. Parameter seasonality was not obvious and it was more apparent in some locations than in others, depending on the seasonality of the rainfall statistics. Cross-validation was used to assess the validity of the parameter maps. The results indicate that the suggested maps reproduce well the observed rainfall statistics for different accumulation intervals, except for the lag-1 autocorrelation coefficient. The boundaries of the expected residual, with 95% confidence, between the observed rainfall statistics and the simulated rainfall statistics based on the map parameters were approximately ±0.064 mm hr-1, ±1.63 mm2 hr-2, ±0.16, and ±0.030 for the mean, variance, lag-1 autocorrelation and probability of zero rainfall at hourly accumulation levels, respectively. The estimated parameter values were also used to estimate the storm and rain cell characteristics.

  5. Introducing a decomposition rate modifier in the Rothamsted Carbon Model to predict soil organic carbon stocks in saline soils.

    Science.gov (United States)

    Setia, Raj; Smith, Pete; Marschner, Petra; Baldock, Jeff; Chittleborough, David; Smith, Jo

    2011-08-01

    Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils

  6. Modeling thermal inkjet and cell printing process using modified pseudopotential and thermal lattice Boltzmann methods

    Science.gov (United States)

    Sohrabi, Salman; Liu, Yaling

    2018-03-01

    Pseudopotential lattice Boltzmann methods (LBMs) can simulate a phase transition in high-density ratio multiphase flow systems. If coupled with thermal LBMs through equation of state, they can be used to study instantaneous phase transition phenomena with a high-temperature gradient where only one set of formulations in an LBM system can handle liquid, vapor, phase transition, and heat transport. However, at lower temperatures an unrealistic spurious current at the interface introduces instability and limits its application in real flow system. In this study, we proposed new modifications to the LBM system to minimize a spurious current which enables us to study nucleation dynamic at room temperature. To demonstrate the capabilities of this approach, the thermal ejection process is modeled as one example of a complex flow system. In an inkjet printer, a thermal pulse instantly heats up the liquid in a microfluidic chamber and nucleates bubble vapor providing the pressure pulse necessary to eject droplets at high speed. Our modified method can present a more realistic model of the explosive vaporization process since it can also capture a high-temperature/density gradient at nucleation region. Thermal inkjet technology has been successfully applied for printing cells, but cells are susceptible to mechanical damage or death as they squeeze out of the nozzle head. To study cell deformation, a spring network model, representing cells, is connected to the LBM through the immersed boundary method. Looking into strain and stress distribution of a cell membrane at its most deformed state, it is found that a high stretching rate effectively increases the rupture tension. In other words, membrane deformation energy is released through creation of multiple smaller nanopores rather than big pores. Overall, concurrently simulating multiphase flow, phase transition, heat transfer, and cell deformation in one unified LB platform, we are able to provide a better insight into the

  7. The effect of modifiable risk factors on geographic mortality differentials: a modelling study

    Directory of Open Access Journals (Sweden)

    Stevenson Christopher E

    2012-01-01

    Full Text Available Abstract Background Australian mortality rates are higher in regional and remote areas than in major cities. The degree to which this is driven by variation in modifiable risk factors is unknown. Methods We applied a risk prediction equation incorporating smoking, cholesterol and blood pressure to a national, population based survey to project all-causes mortality risk by geographic region. We then modelled life expectancies at different levels of mortality risk by geographic region using a risk percentiles model. Finally we set high values of each risk factor to a target level and modelled the subsequent shift in the population to lower levels of mortality risk and longer life expectancy. Results Survival is poorer in both Inner Regional and Outer Regional/Remote areas compared to Major Cities for men and women at both high and low levels of predicted mortality risk. For men smoking, high cholesterol and high systolic blood pressure were each associated with the mortality difference between Major Cities and Outer Regional/Remote areas--accounting for 21.4%, 20.3% and 7.7% of the difference respectively. For women smoking and high cholesterol accounted for 29.4% and 24.0% of the difference respectively but high blood pressure did not contribute to the observed mortality differences. The three risk factors taken together accounted for 45.4% (men and 35.6% (women of the mortality difference. The contribution of risk factors to the corresponding differences for inner regional areas was smaller, with only high cholesterol and smoking contributing to the difference in men-- accounting for 8.8% and 6.3% respectively-- and only smoking contributing to the difference in women--accounting for 12.3%. Conclusions These results suggest that health intervention programs aimed at smoking, blood pressure and total cholesterol could have a substantial impact on mortality inequities for Outer Regional/Remote areas.

  8. Modeling thermal inkjet and cell printing process using modified pseudopotential and thermal lattice Boltzmann methods.

    Science.gov (United States)

    Sohrabi, Salman; Liu, Yaling

    2018-03-01

    Pseudopotential lattice Boltzmann methods (LBMs) can simulate a phase transition in high-density ratio multiphase flow systems. If coupled with thermal LBMs through equation of state, they can be used to study instantaneous phase transition phenomena with a high-temperature gradient where only one set of formulations in an LBM system can handle liquid, vapor, phase transition, and heat transport. However, at lower temperatures an unrealistic spurious current at the interface introduces instability and limits its application in real flow system. In this study, we proposed new modifications to the LBM system to minimize a spurious current which enables us to study nucleation dynamic at room temperature. To demonstrate the capabilities of this approach, the thermal ejection process is modeled as one example of a complex flow system. In an inkjet printer, a thermal pulse instantly heats up the liquid in a microfluidic chamber and nucleates bubble vapor providing the pressure pulse necessary to eject droplets at high speed. Our modified method can present a more realistic model of the explosive vaporization process since it can also capture a high-temperature/density gradient at nucleation region. Thermal inkjet technology has been successfully applied for printing cells, but cells are susceptible to mechanical damage or death as they squeeze out of the nozzle head. To study cell deformation, a spring network model, representing cells, is connected to the LBM through the immersed boundary method. Looking into strain and stress distribution of a cell membrane at its most deformed state, it is found that a high stretching rate effectively increases the rupture tension. In other words, membrane deformation energy is released through creation of multiple smaller nanopores rather than big pores. Overall, concurrently simulating multiphase flow, phase transition, heat transfer, and cell deformation in one unified LB platform, we are able to provide a better insight into the

  9. Evaluation of the modified HTK solution in pancreas transplantation—An experimental model

    Directory of Open Access Journals (Sweden)

    Majid Esmaeilzadeh

    2016-04-01

    Conclusion: The modified HTK solution could preserve the pancreas for the preservation of the graft with similar results to those observed for standard solutions without any significant difference. The trend showed that the pathological finding in the UW group was not as good as that in the modified HTK and standard HTK groups.

  10. Modified SEAGULL

    Science.gov (United States)

    Salas, M. D.; Kuehn, M. S.

    1994-01-01

    Original version of program incorporated into program SRGULL (LEW-15093) for use on National Aero-Space Plane project, its duty being to model forebody, inlet, and nozzle portions of vehicle. However, real-gas chemistry effects in hypersonic flow fields limited accuracy of that version, because it assumed perfect-gas properties. As a result, SEAGULL modified according to real-gas equilibrium-chemistry methodology. This program analyzes two-dimensional, hypersonic flows of real gases. Modified version of SEAGULL maintains as much of original program as possible, and retains ability to execute original perfect-gas version.

  11. A Mathematical Model of the Modified Atmosphere Packaging (MAP System for the Gas Transmission Rate of Fruit Produce

    Directory of Open Access Journals (Sweden)

    Li Li

    2010-01-01

    Full Text Available A mathematical model to predict oxygen, carbon dioxide, and water vapour exchanges in non-perforated and micro-perforated modified atmosphere packaging films has successfully been proposed. The transmission rate of gases was measured for films with thickness of 0.03 and 0.05 mm, perforation diameters of 0.5 and 2.0 mm, and temperatures of 0, 10 and 20 °C. Under most conditions, the increase in temperature and perforation diameter increased the transmission rate of oxygen, carbon dioxide, and water vapour, whereas the increase in film thickness decreased the transmission rate of the various gases. Validation of the proposed modified atmosphere packaging model was found to yield good prediction for gas concentrations and percentage losses in the mass of the produce after comparison with the experimental results of modified atmosphere packaging for tomato (Lycopersicon esculentum.

  12. Modelling of electric tree progression due to space charge modified fields

    International Nuclear Information System (INIS)

    Seralathan, K E; Mahajan, A; Gupta, Nandini

    2008-01-01

    Tree initiation and growth require localized field enhancement that results in material erosion and formation of tree channels. Tree progression is linked to partial discharges within the tree tubules, characterized by recurrent periods of activity followed by quiescent states. Charge builds up across the non-conducting tree channels during the inactive regime, and discharge follows. In this work, the role of the space charge modified field during the non-discharging regime in deciding the site of subsequent discharges and thereby shaping tree structures is studied. A simple stochastic model was developed, in order to understand the respective effects of charges trapped on the walls of tree tubules, at channel tips, or in the volume of the dielectric. While some charge distributions are seen to arrest tree growth, others encourage axial growth towards the other electrode, and some aid in producing bushy trees clustered around the needle tip. The effect of carbon deposition within tree channels, making them effectively conducting, was also investigated. The insights gained from the simulations were successfully used to explain tree growth in the laboratory under high- and low-field conditions

  13. Computational cardiology: the bidomain based modified Hill model incorporating viscous effects for cardiac defibrillation

    Science.gov (United States)

    Cansız, Barış; Dal, Hüsnü; Kaliske, Michael

    2017-10-01

    Working mechanisms of the cardiac defibrillation are still in debate due to the limited experimental facilities and one-third of patients even do not respond to cardiac resynchronization therapy. With an aim to develop a milestone towards reaching the unrevealed mechanisms of the defibrillation phenomenon, we propose a bidomain based finite element formulation of cardiac electromechanics by taking into account the viscous effects that are disregarded by many researchers. To do so, the material is deemed as an electro-visco-active material and described by the modified Hill model (Cansız et al. in Comput Methods Appl Mech Eng 315:434-466, 2017). On the numerical side, we utilize a staggered solution method, where the elliptic and parabolic part of the bidomain equations and the mechanical field are solved sequentially. The comparative simulations designate that the viscoelastic and elastic formulations lead to remarkably different outcomes upon an externally applied electric field to the myocardial tissue. Besides, the achieved framework requires significantly less computational time and memory compared to monolithic schemes without loss of stability for the presented examples.

  14. Surface science and model catalysis with ionic liquid-modified materials.

    Science.gov (United States)

    Steinrück, H-P; Libuda, J; Wasserscheid, P; Cremer, T; Kolbeck, C; Laurin, M; Maier, F; Sobota, M; Schulz, P S; Stark, M

    2011-06-17

    Materials making use of thin ionic liquid (IL) films as support-modifying functional layer open up a variety of new possibilities in heterogeneous catalysis, which range from the tailoring of gas-surface interactions to the immobilization of molecularly defined reactive sites. The present report reviews recent progress towards an understanding of "supported ionic liquid phase (SILP)" and "solid catalysts with ionic liquid layer (SCILL)" materials at the microscopic level, using a surface science and model catalysis type of approach. Thin film IL systems can be prepared not only ex-situ, but also in-situ under ultrahigh vacuum (UHV) conditions using atomically well-defined surfaces as substrates, for example by physical vapor deposition (PVD). Due to their low vapor pressure, these systems can be studied in UHV using the full spectrum of surface science techniques. We discuss general strategies and considerations of this approach and exemplify the information available from complementary methods, specifically photoelectron spectroscopy and surface vibrational spectroscopy. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Modified model of neutron resonance widths distribution. Results of total gamma-widths approximation

    International Nuclear Information System (INIS)

    Sukhovoj, A.M.; Khitrov, V.A.

    2011-01-01

    Functional dependences of probability to observe given Γ n 0 value and algorithms for determination of the most probable magnitudes of the modified model of resonance parameter distributions were used for analysis of the experimental data on the total radiative widths of neutron resonances. As in the case of neutron widths, precise description of the Γ γ spectra requires a superposition of three and more probability distributions for squares of the random normally distributed values with different nonzero average and nonunit dispersion. This result confirms the preliminary conclusion obtained earlier at analysis of Γ n 0 that practically in all 56 tested sets of total gamma widths there are several groups noticeably differing from each other by the structure of their wave functions. In addition, it was determined that radiative widths are much more sensitive than the neutron ones to resonance wave functions structure. Analysis of early obtained neutron reduced widths distribution parameters for 157 resonance sets in the mass region of nuclei 35 ≤ A ≤ 249 was also performed. It was shown that the experimental values of widths can correspond with high probability to superposition of several expected independent distributions with their nonzero mean values and nonunit dispersion

  16. Modified Becke-Johnson exchange potential: improved modeling of lead halides for solar cell applications

    Directory of Open Access Journals (Sweden)

    Radi A. Jishi

    2016-01-01

    Full Text Available We report first-principles calculations, within density functional theory, on the lead halide compounds PbCl2, PbBr2, and CH3NH3PbBr3−xClx, taking into account spin-orbit coupling. We show that, when the modified Becke-Johnson exchange potential is used with a suitable choice of defining parameters, excellent agreement between calculations and experiment is obtained. The computational model is then used to study the effect of replacing the methylammonium cation in CH3NH3PbI3 and CH3NH3PbBr3 with either N2H5+or N2H3+, which have slightly smaller ionic radii than methylammonium. We predict that a considerable downshift in the values of the band gaps occurs with this replacement. The resulting compounds would extend optical absorption down to the near-infrared region, creating excellent light harvesters for solar cells.

  17. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Directory of Open Access Journals (Sweden)

    Sergeev Daniil

    2017-01-01

    Full Text Available Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS, in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1 the use of high-speed video recording (1000-10000 frames/sec with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2 the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3 adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4 using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  18. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Science.gov (United States)

    Sergeev, Daniil; Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Bopp, Maximilian; Jaehne, Bernd

    Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV) was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1) the use of high-speed video recording (1000-10000 frames/sec) with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2) the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3) adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4) using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  19. Modeling the ferrochelatase c.315-48C modifier mutation for erythropoietic protoporphyria (EPP in mice

    Directory of Open Access Journals (Sweden)

    Jasmin Barman-Aksözen

    2017-03-01

    Full Text Available Erythropoietic protoporphyria (EPP is caused by deficiency of ferrochelatase (FECH, which incorporates iron into protoporphyrin IX (PPIX to form heme. Excitation of accumulated PPIX by light generates oxygen radicals that evoke excessive pain and, after longer light exposure, cause ulcerations in exposed skin areas of individuals with EPP. Moreover, ∼5% of the patients develop a liver dysfunction as a result of PPIX accumulation. Most patients (∼97% have a severe FECH mutation (Mut in trans to an intronic polymorphism (c.315-48C, which reduces ferrochelatase synthesis by stimulating the use of an aberrant 3′ splice site 63 nt upstream of the normal site for exon 4. In contrast, with the predominant c.315-48T allele, the correct splice site is mostly used, and individuals with a T/Mut genotype do not develop EPP symptoms. Thus, the C allele is a potential target for therapeutic approaches that modify this splicing decision. To provide a model for pre-clinical studies of such approaches, we engineered a mouse containing a partly humanized Fech gene with the c.315-48C polymorphism. F1 hybrids obtained by crossing these mice with another inbred line carrying a severe Fech mutation (named m1Pas show a very strong EPP phenotype that includes elevated PPIX in the blood, enlargement of liver and spleen, anemia, as well as strong pain reactions and skin lesions after a short period of light exposure. In addition to the expected use of the aberrant splice site, the mice also show a strong skipping of the partly humanized exon 3. This will limit the use of this model for certain applications and illustrates that engineering of a hybrid gene may have unforeseeable consequences on its splicing.

  20. Modelling biological control with wild-type and genetically modified baculoviruses in the Helicoverpa armigera-cotton system

    NARCIS (Netherlands)

    Sun, X.; Werf, van der W.; Bianchi, F.J.J.A.; Hu, Z.; Vlak, J.M.

    2006-01-01

    A comprehensive model was developed to simulate virus epizootics in a stage structured insect population and analyse scenarios for the biological control of cotton bollworm (CBW), Helicoverpa armigera, in cotton, using wild-type or genetically modified baculoviruses. In simulations on dosage and

  1. Development of alternative sulfur dioxide control strategies for a metropolitan area and its environs, utilizing a modified climatological dispersion model

    Science.gov (United States)

    K. J. Skipka; D. B. Smith

    1977-01-01

    Alternative control strategies were developed for achieving compliance with ambient air quality standards in Portland, Maine, and its environs, using a modified climatological dispersion model (CDM) and manipulating the sulfur content of the fuel oil consumed in four concentric zones. Strategies were evaluated for their impact on ambient air quality, economics, and...

  2. A Modified Gash Model for Estimating Rainfall Interception Loss of Forest Using Remote Sensing Observations at Regional Scale

    Directory of Open Access Journals (Sweden)

    Yaokui Cui

    2014-04-01

    Full Text Available Rainfall interception loss of forest is an important component of water balance in a forested ecosystem. The Gash analytical model has been widely used to estimate the forest interception loss at field scale. In this study, we proposed a simple model to estimate rainfall interception loss of heterogeneous forest at regional scale with several reasonable assumptions using remote sensing observations. The model is a modified Gash analytical model using easily measured parameters of forest structure from satellite data and extends the original Gash model from point-scale to the regional scale. Preliminary results, using remote sensing data from Moderate Resolution Imaging Spectroradiometer (MODIS products, field measured rainfall data, and meteorological data of the Automatic Weather Station (AWS over a picea crassifolia forest in the upper reaches of the Heihe River Basin in northwestern China, showed reasonable accuracy in estimating rainfall interception loss at both the Dayekou experimental site (R2 = 0.91, RMSE = 0.34 mm∙d −1 and the Pailugou experimental site (R2 = 0.82, RMSE = 0.6 mm∙d −1, compared with ground measurements based on per unit area of forest. The interception loss map of the study area was shown to be strongly heterogeneous. The modified model has robust physics and is insensitive to the input parameters, according to the sensitivity analysis using numerical simulations. The modified model appears to be stable and easy to be applied for operational estimation of interception loss over large areas.

  3. Improvement of and Parameter Identification for the Bimodal Time-Varying Modified Kanai-Tajimi Power Spectral Model

    Directory of Open Access Journals (Sweden)

    Huiguo Chen

    2017-01-01

    Full Text Available Based on the Kanai-Tajimi power spectrum filtering method proposed by Du Xiuli et al., a genetic algorithm and a quadratic optimization identification technique are employed to improve the bimodal time-varying modified Kanai-Tajimi power spectral model and the parameter identification method proposed by Vlachos et al. Additionally, a method for modeling time-varying power spectrum parameters for ground motion is proposed. The 8244 Orion and Chi-Chi earthquake accelerograms are selected as examples for time-varying power spectral model parameter identification and ground motion simulations to verify the feasibility and effectiveness of the improved bimodal time-varying modified Kanai-Tajimi power spectral model. The results of this study provide important references for designing ground motion inputs for seismic analyses of major engineering structures.

  4. Numerical simulation of the self-pumped long Josephson junction using a modified sine-Gordon model

    International Nuclear Information System (INIS)

    Sobolev, A.S.; Pankratov, A.L.; Mygind, J.

    2006-01-01

    We have numerically investigated the dynamics of a long Josephson junction (flux-flow oscillator) biased by a DC current in the presence of magnetic field. The study is performed in the frame of the modified sine-Gordon model, which includes the surface losses, RC-load at both FFO ends and the self-pumping effect. In our model the dumping parameter depends both on the spatial coordinate and the amplitude of the AC voltage. In order to find the DC FFO voltage the damping parameter has to be calculated by successive approximations and time integration of the perturbed sine-Gordon equation. The modified model, which accounts for the presence of the superconducting gap, gives better qualitative agreement with experimental results compare to the conventional sine-Gordon model

  5. Thermal radiation transfer calculations in combustion fields using the SLW model coupled with a modified reference approach

    Science.gov (United States)

    Darbandi, Masoud; Abrar, Bagher

    2018-01-01

    The spectral-line weighted-sum-of-gray-gases (SLW) model is considered as a modern global model, which can be used in predicting the thermal radiation heat transfer within the combustion fields. The past SLW model users have mostly employed the reference approach to calculate the local values of gray gases' absorption coefficient. This classical reference approach assumes that the absorption spectra of gases at different thermodynamic conditions are scalable with the absorption spectrum of gas at a reference thermodynamic state in the domain. However, this assumption cannot be reasonable in combustion fields, where the gas temperature is very different from the reference temperature. Consequently, the results of SLW model incorporated with the classical reference approach, say the classical SLW method, are highly sensitive to the reference temperature magnitude in non-isothermal combustion fields. To lessen this sensitivity, the current work combines the SLW model with a modified reference approach, which is a particular one among the eight possible reference approach forms reported recently by Solovjov, et al. [DOI: 10.1016/j.jqsrt.2017.01.034, 2017]. The combination is called "modified SLW method". This work shows that the modified reference approach can provide more accurate total emissivity calculation than the classical reference approach if it is coupled with the SLW method. This would be particularly helpful for more accurate calculation of radiation transfer in highly non-isothermal combustion fields. To approve this, we use both the classical and modified SLW methods and calculate the radiation transfer in such fields. It is shown that the modified SLW method can almost eliminate the sensitivity of achieved results to the chosen reference temperature in treating highly non-isothermal combustion fields.

  6. EMPIRICAL TESTING OF MODIFIED BLACK-SCHOLES OPTION PRICING MODEL FORMULA ON NSE DERIVATIVE MARKET IN INDIA

    Directory of Open Access Journals (Sweden)

    Ambrish Gupta

    2013-01-01

    Full Text Available The main objectives of this paper are to incorporate modification in Black-Scholes option pricing model formula by adding some new variables on the basis of given assumption related to risk-free interest rate, and also shows the calculation process of new risk-free interest rate on the basis of modified variable. This paper also identifies the various situations in empirical testing of modified and original Black-Scholes formula with respect to the market value on the basis of assumed and calculated risk-free interest rate.

  7. Combining the modified Skyrme-like model and the local density approximation to determine the symmetry energy of nuclear matter

    Science.gov (United States)

    Liu, Jian; Ren, Zhongzhou; Xu, Chang

    2018-07-01

    Combining the modified Skyrme-like model and the local density approximation model, the slope parameter L of symmetry energy is extracted from the properties of finite nuclei with an improved iterative method. The calculations of the iterative method are performed within the framework of the spherical symmetry. By choosing 200 neutron rich nuclei on 25 isotopic chains as candidates, the slope parameter is constrained to be 50 MeV nuclear matter can be obtained together.

  8. Efektivitas Model Pembelajaran Modified Free Inquiry (Mfi) Disertai Peer Tutoring Terhadap Prestasi Belajar Siswa Pada Materi Hidrolisis Garam Siswa Kelas XI Semester Genap SMA N 1 Kartasura Tahun Pelajaran 2013/2014

    OpenAIRE

    Suryanto, Eko; Susanti, Elfi; Saputro, Sulistyo

    2015-01-01

    Penelitian ini bertujuan untuk mengetahui (1) efektivitas penggunaan model pembelajaran Modified Free Inquiry disertai Peer Tutoring terhadap prestasi belajar siswa pada materi hidrolisis garam; (2) efektivitas penggunaan model pembelajaran Modified Free Inquiry terhadap prestasi belajar siswa pada materi hidrolisis garam; (3) efektivitas penggunaan model pembelajaran Modified Free Inquiry disertai Peer Tutoring dan model pembelajaran Modified Free Inquiry terhadap prestasi belajar siswa pada...

  9. Disease modifying and antiangiogenic activity of 2-Methoxyestradiol in a murine model of rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Moore Elizabeth G

    2009-05-01

    study parameters and prevented neovascularization into the joint. Examination of gene expression on dissected hind limbs from mice treated for 5 or 14 days with 2ME2 showed inhibition of inflammatory cytokine message for IL-1β, TNF-α, IL-6 and IL-17, as well as the angiogenic cytokines, VEGF and FGF-2. Conclusion These data demonstrate that in the CAIA mouse model of RA, 2ME2 has disease modifying activity that is at least partially attributable to the inhibition of neovascular development. Further, the data suggests new mechanistic points of intervention for 2ME2 in RA, specifically inhibition of inflammatory mediators and osteoclast activity.

  10. An application of the modified turbulent model for analyzing supercritical heat transfer phenomena in a nuclear system

    International Nuclear Information System (INIS)

    Seo, Kyoung-Woo; Park, Cheon-Tae; Seo, Jae-Kwang; Kim, Moo-Hwan; Corradini, Michael L.

    2007-01-01

    For understanding the characteristic of a supercritical fluid heat transfer, we proposed a new parameter, a global Froude number (Fr), dependent on the heat and mass flux, to determine under what conditions the buoyancy effect is dominant and the reduction of the heat transfer rate. In the region of the global Fr>0.01, variable property effects, which may occur at a high heat flux, and buoyancy effects, which could occur at a low mass flux, make the existing standard turbulent model such as the standard wall function not suitably accurate to calculate the heat transfer in supercritical fluid, needed for a reactor thermal-hydraulics simulation and design. Therefore, the turbulence model, especially near the wall, the wall function for a momentum, applicable for a range of supercritical fluid conditions was modified. The modified models deal with a buoyancy, acceleration, and the variable property effect for supercritical conditions

  11. Modified ADM1 for modeling free ammonia inhibition in anaerobic acidogenic fermentation with high-solid sludge.

    Science.gov (United States)

    Bai, Jie; Liu, He; Yin, Bo; Ma, Huijun; Chen, Xinchun

    2017-02-01

    Anaerobic acidogenic fermentation with high-solid sludge is a promising method for volatile fatty acid (VFA) production to realize resource recovery. In this study, to model inhibition by free ammonia in high-solid sludge fermentation, the anaerobic digestion model No. 1 (ADM1) was modified to simulate the VFA generation in batch, semi-continuous and full scale sludge. The ADM1 was operated on the platform AQUASIM 2.0. Three kinds of inhibition forms, e.g., simple inhibition, Monod and non-inhibition forms, were integrated into the ADM1 and tested with the real experimental data for batch and semi-continuous fermentation, respectively. The improved particle swarm optimization technique was used for kinetic parameter estimation using the software MATLAB 7.0. In the modified ADM1, the K s of acetate is 0.025, the k m,ac is 12.51, and the K I_NH3 is 0.02, respectively. The results showed that the simple inhibition model could simulate the VFA generation accurately while the Monod model was the better inhibition kinetics form in semi-continuous fermentation at pH10.0. Finally, the modified ADM1 could successfully describe the VFA generation and ammonia accumulation in a 30m 3 full-scale sludge fermentation reactor, indicating that the developed model can be applicable in high-solid sludge anaerobic fermentation. Copyright © 2016. Published by Elsevier B.V.

  12. Fast Computation of Ground Motion Shaking Map base on the Modified Stochastic Finite Fault Modeling

    Science.gov (United States)

    Shen, W.; Zhong, Q.; Shi, B.

    2012-12-01

    Rapidly regional MMI mapping soon after a moderate-large earthquake is crucial to loss estimation, emergency services and planning of emergency action by the government. In fact, many countries show different degrees of attention on the technology of rapid estimation of MMI , and this technology has made significant progress in earthquake-prone countries. In recent years, numerical modeling of strong ground motion has been well developed with the advances of computation technology and earthquake science. The computational simulation of strong ground motion caused by earthquake faulting has become an efficient way to estimate the regional MMI distribution soon after earthquake. In China, due to the lack of strong motion observation in network sparse or even completely missing areas, the development of strong ground motion simulation method has become an important means of quantitative estimation of strong motion intensity. In many of the simulation models, stochastic finite fault model is preferred to rapid MMI estimating for its time-effectiveness and accuracy. In finite fault model, a large fault is divided into N subfaults, and each subfault is considered as a small point source. The ground motions contributed by each subfault are calculated by the stochastic point source method which is developed by Boore, and then summed at the observation point to obtain the ground motion from the entire fault with a proper time delay. Further, Motazedian and Atkinson proposed the concept of Dynamic Corner Frequency, with the new approach, the total radiated energy from the fault and the total seismic moment are conserved independent of subfault size over a wide range of subfault sizes. In current study, the program EXSIM developed by Motazedian and Atkinson has been modified for local or regional computations of strong motion parameters such as PGA, PGV and PGD, which are essential for MMI estimating. To make the results more reasonable, we consider the impact of V30 for the

  13. A modified two-fluid model for the application of two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Sun, X.; Ishii, M.; Kelly, J.

    2003-01-01

    This paper presents the modified two-fluid model that is ready to be applied in the approach of the two-group interfacial area transport equation. The two-group interfacial area transport equation was developed to provide a mechanistic constitutive relation for the interfacial area concentration in the two-fluid model. In the two-group transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 while cap/slug/churn-turbulent bubbles as Group 2. Therefore, this transport equation can be employed in the flow regimes spanning from bubbly, cap bubbly, slug to churn-turbulent flows. However, the introduction of the two groups of bubbles requires two gas velocity fields. Yet it is not desirable to solve two momentum equations for the gas phase alone. In the current modified two-fluid model, a simplified approach is proposed. The momentum equation for the averaged velocity of both Group-1 and Group-2 bubbles is retained. By doing so, the velocity difference between Group-1 and Group-2 bubbles needs to be determined. This may be made either based on simplified momentum equations for both Group-1 and Group-2 bubbles or by a modified drift-flux model

  14. Modified chloride diffusion model for concrete under the coupling effect of mechanical load and chloride salt environment

    Science.gov (United States)

    Lei, Mingfeng; Lin, Dayong; Liu, Jianwen; Shi, Chenghua; Ma, Jianjun; Yang, Weichao; Yu, Xiaoniu

    2018-03-01

    For the purpose of investigating lining concrete durability, this study derives a modified chloride diffusion model for concrete based on the odd continuation of boundary conditions and Fourier transform. In order to achieve this, the linear stress distribution on a sectional structure is considered, detailed procedures and methods are presented for model verification and parametric analysis. Simulation results show that the chloride diffusion model can reflect the effects of linear stress distribution of the sectional structure on the chloride diffusivity with reliable accuracy. Along with the natural environmental characteristics of practical engineering structures, reference value ranges of model parameters are provided. Furthermore, a chloride diffusion model is extended for the consideration of multi-factor coupling of linear stress distribution, chloride concentration and diffusion time. Comparison between model simulation and typical current research results shows that the presented model can produce better considerations with a greater universality.

  15. On modeling the sound propagation through a lined duct with a modified Ingard-Myers boundary condition

    Science.gov (United States)

    Yang, Cheng; Fang, Yi; Zhao, Chao; Zhang, Xin

    2018-06-01

    A duct acoustics model is an essential component of an impedance eduction technique and its computation cost determines the impedance measurement efficiency. In this paper, a model is developed for the sound propagation through a lined duct carrying a uniform mean flow. In contrast to many existing models, the interface between the liner and the duct field is defined with a modified Ingard-Myers boundary condition that takes account of the effect of the boundary layer above the liner. A mode-matching method is used to couple the unlined and lined duct segments for the model development. For the lined duct segment, the eigenvalue problem resulted from the modified boundary condition is solved by an integration scheme which, on the one hand, allows the lined duct modes to be computed in an efficient manner, and on the other hand, orders the modes automatically. The duct acoustics model developed from the solved lined duct modes is shown to converge more rapidly than the one developed from the rigid-walled duct modes. Validation against the experiment data in the literature shows that the proposed model is able to predict more accurately the liner performance measured by the two-source method. This, however, cannot be made by a duct acoustics model associated with the conventional Ingard-Myers boundary condition. The proposed model has the potential to be integrated into an impedance eduction technique for more reliable liner measurement.

  16. Modelling of bow-tie microstrip antennas using modified locally conformal FDTD method

    NARCIS (Netherlands)

    George, J.

    2000-01-01

    An analysis of bow-tie microstrip antennas is presented based on the use of the modified locally conformal finite-difference time-domain (FDTD) method. This approach enables the number of cells along the antenna length and width to be chosen independently of the antenna central width, which helps to

  17. Investigation of the interaction between modified ISCOMs and stratum corneum lipid model systems

    DEFF Research Database (Denmark)

    Madsen, Henriette Baun; Arboe-Andersen, Helle M.; Rozlosnik, Noemi

    2010-01-01

    The modified ISCOMs, so-called Posintro (TM) nanoparticles, provide an opportunity for altering the surface charge of the particles, which influences their affinity for the negatively charged antigen sites, cell membranes and lipids in the skin. Hypothetically, this increases the passage of the I...

  18. Chromatographic and traditional albumin isotherms on cellulose: a model for wound protein adsorption on modified cotton

    Science.gov (United States)

    Albumin is the most abundant protein found in healing wounds. Traditional and chromatogrpahic protein isotherms of albumin binding on modified cotton fibers are useful in understanding albumin binding to cellulose wound dressings. An important consideration in the design of cellulosic wound dressin...

  19. Modified local diatomite as potential functional drug carrier--A model study for diclofenac sodium.

    Science.gov (United States)

    Janićijević, Jelena; Krajišnik, Danina; Čalija, Bojan; Vasiljević, Bojana Nedić; Dobričić, Vladimir; Daković, Aleksandra; Antonijević, Milan D; Milić, Jela

    2015-12-30

    Diatomite makes a promising candidate for a drug carrier because of its high porosity, large surface area, modifiable surface chemistry and biocompatibility. Herein, refined diatomite from Kolubara coal basin, which complied with the pharmacopoeial requirements for heavy metals content and microbiological quality, was used as a starting material. Inorganic modification of the starting material was performed through a simple, one-step procedure. Significant increase in adsorbent loading with diclofenac sodium (DS) was achieved after the modification process (∼373mg/g) which enabled the preparation of comprimates containing therapeutic dose of the adsorbed drug. Adsorption of DS onto modified diatomite resulted in the alteration of the drug's XRD pattern and FTIR spectrum. In vitro drug release studies in phosphate buffer pH 7.5 demonstrated prolonged DS release over 8h from comprimates containing DS adsorbed on modified diatomite (up to 37% after 8h) and those containing physical mixture of the same composition (up to 45% after 8h). The results of in vivo toxicity testing on mice pointed on potential safety of both unmodified (starting) and modified diatomite. All these findings favor the application of diatomite as a potential functional drug carrier. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. A virtual surgical training system that simulates cutting of soft tissue using a modified pre-computed elastic model.

    Science.gov (United States)

    Toe, Kyaw Kyar; Huang, Weimin; Yang, Tao; Duan, Yuping; Zhou, Jiayin; Su, Yi; Teo, Soo-Kng; Kumar, Selvaraj Senthil; Lim, Calvin Chi-Wan; Chui, Chee Kong; Chang, Stephen

    2015-08-01

    This work presents a surgical training system that incorporates cutting operation of soft tissue simulated based on a modified pre-computed linear elastic model in the Simulation Open Framework Architecture (SOFA) environment. A precomputed linear elastic model used for the simulation of soft tissue deformation involves computing the compliance matrix a priori based on the topological information of the mesh. While this process may require a few minutes to several hours, based on the number of vertices in the mesh, it needs only to be computed once and allows real-time computation of the subsequent soft tissue deformation. However, as the compliance matrix is based on the initial topology of the mesh, it does not allow any topological changes during simulation, such as cutting or tearing of the mesh. This work proposes a way to modify the pre-computed data by correcting the topological connectivity in the compliance matrix, without re-computing the compliance matrix which is computationally expensive.

  1. Adaptive integral backstepping sliding mode control for opto-electronic tracking system based on modified LuGre friction model

    Science.gov (United States)

    Yue, Fengfa; Li, Xingfei; Chen, Cheng; Tan, Wenbin

    2017-12-01

    In order to improve the control accuracy and stability of opto-electronic tracking system fixed on reef or airport under friction and external disturbance conditions, adaptive integral backstepping sliding mode control approach with friction compensation is developed to achieve accurate and stable tracking for fast moving target. The nonlinear observer and slide mode controller based on modified LuGre model with friction compensation can effectively reduce the influence of nonlinear friction and disturbance of this servo system. The stability of the closed-loop system is guaranteed by Lyapunov theory. The steady-state error of the system is eliminated by integral action. The adaptive integral backstepping sliding mode controller and its performance are validated by a nonlinear modified LuGre dynamic model of the opto-electronic tracking system in simulation and practical experiments. The experiment results demonstrate that the proposed controller can effectively realise the accuracy and stability control of opto-electronic tracking system.

  2. Application of the Modified Vlasov Model to the Free Vibration Analysis of Thick Plates Resting on Elastic Foundations

    OpenAIRE

    Ozgan, Korhan; Daloglu, Ayse T.

    2009-01-01

    The Modified Vlasov Model is applied to the free vibration analysis of thick plates resting on elastic foundations. The effects of the subsoil depth, plate dimensions and their ratio, the value of the vertical deformation parameter within the subsoil on the frequency parameters of plates on elastic foundations are investigated. A four-noded, twelve degrees of freedom quadrilateral finite element (PBQ4) is used for plate bending analysis based on Mindlin plate theory which is effectively appli...

  3. A modified Gaussian model for the thermal plume from a ground-based heat source in a cross-wind

    International Nuclear Information System (INIS)

    Selander, W.N.; Barry, P.J.; Robertson, E.

    1990-06-01

    An array of propane burners operating at ground level in a cross-wind was used as a heat source to establish a blown-over thermal plume. A three-dimensional array of thermocouples was used to continuously measure the plume temperature downwind from the source. The resulting data were used to correlate the parameters of a modified Gaussian model for plume rise and dispersion with source strength, wind speed, and atmospheric dispersion parameters

  4. Optical phonons in cubic AlxGa1-xN approached by the modified random element isodisplacement model

    International Nuclear Information System (INIS)

    Liu, M.S.; Bursill, L.A.; Prawer, S.

    1998-01-01

    The behaviour of longitudinal and transverse optical phonons in cubic Al x Ga l-x N are derived theoretically as a function of the concentration x (0≤x≤1). The calculation is based on a Modified Random Element Isodisplacement model which considers the interactions from the nearest neighbor and second neighbor atoms. We find one-mode behavior in Al x Ga l-x N where the phonon frequency in general varies continuously and approximately linearly with x. (author)

  5. Position control of a single pneumatic artificial muscle with hysteresis compensation based on modified Prandtl-Ishlinskii model.

    Science.gov (United States)

    Zang, Xizhe; Liu, Yixiang; Heng, Shuai; Lin, Zhenkun; Zhao, Jie

    2017-01-01

    High-performance position control of pneumatic artificial muscles is limited by their inherent nonlinearity and hysteresis. This study aims to model the length/pressure hysteresis of a single pneumatic artificial muscle and to realize its accurate position tracking control with forward hysteresis compensation. The classical Prandtl-Ishlinskii model is widely used in hysteresis modelling and compensation. But it is only effective for symmetric hysteresis. Therefore, a modified Prandtl-Ishlinskii model is built to characterize the asymmetric length/pressure hysteresis of a single pneumatic artificial muscle, by replacing the classical play operators with two more flexible elementary operators to independently describe the ascending branch and descending branch of hysteresis loops. On the basis, a position tracking controller, which is composed of cascade forward hysteresis compensation and simple proportional pressure controller, is designed for the pneumatic artificial muscle. Experiment results show that the MPI model can reproduce the length/pressure hysteresis of the pneumatic artificial muscle, and the proposed controller for the pneumatic artificial muscle can track the reference position signals with high accuracy. By modelling the length/pressure hysteresis with the modified Prandtl-Ishlinskii model and using its inversion for compensation, precise position control of a single pneumatic artificial muscle is achieved.

  6. Model-independent constraints on modified gravity from current data and from the Euclid and SKA future surveys

    International Nuclear Information System (INIS)

    Taddei, Laura; Martinelli, Matteo; Amendola, Luca

    2016-01-01

    The aim of this paper is to constrain modified gravity with redshift space distortion observations and supernovae measurements. Compared with a standard ΛCDM analysis, we include three additional free parameters, namely the initial conditions of the matter perturbations, the overall perturbation normalization, and a scale-dependent modified gravity parameter modifying the Poisson equation, in an attempt to perform a more model-independent analysis. First, we constrain the Poisson parameter Y (also called G eff ) by using currently available f σ 8 data and the recent SN catalog JLA. We find that the inclusion of the additional free parameters makes the constraints significantly weaker than when fixing them to the standard cosmological value. Second, we forecast future constraints on Y by using the predicted growth-rate data for Euclid and SKA missions. Here again we point out the weakening of the constraints when the additional parameters are included. Finally, we adopt as modified gravity Poisson parameter the specific Horndeski form, and use scale-dependent forecasts to build an exclusion plot for the Yukawa potential akin to the ones realized in laboratory experiments, both for the Euclid and the SKA surveys.

  7. Model-independent constraints on modified gravity from current data and from the Euclid and SKA future surveys

    Energy Technology Data Exchange (ETDEWEB)

    Taddei, Laura; Martinelli, Matteo; Amendola, Luca, E-mail: taddei@thphys.uni-heidelberg.de, E-mail: martinelli@lorentz.leidenuniv.nl, E-mail: amendola@thphys.uni-heidelberg.de [Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany)

    2016-12-01

    The aim of this paper is to constrain modified gravity with redshift space distortion observations and supernovae measurements. Compared with a standard ΛCDM analysis, we include three additional free parameters, namely the initial conditions of the matter perturbations, the overall perturbation normalization, and a scale-dependent modified gravity parameter modifying the Poisson equation, in an attempt to perform a more model-independent analysis. First, we constrain the Poisson parameter Y (also called G {sub eff}) by using currently available f σ{sub 8} data and the recent SN catalog JLA. We find that the inclusion of the additional free parameters makes the constraints significantly weaker than when fixing them to the standard cosmological value. Second, we forecast future constraints on Y by using the predicted growth-rate data for Euclid and SKA missions. Here again we point out the weakening of the constraints when the additional parameters are included. Finally, we adopt as modified gravity Poisson parameter the specific Horndeski form, and use scale-dependent forecasts to build an exclusion plot for the Yukawa potential akin to the ones realized in laboratory experiments, both for the Euclid and the SKA surveys.

  8. Regular and chaotic behaviors of plasma oscillations modeled by a modified Duffing equation

    International Nuclear Information System (INIS)

    Enjieu Kadji, H.G.; Chabi Orou, J.B.; Woafo, P.; Abdus Salam International Centre for Theoretical Physics, Trieste

    2005-07-01

    The regular and chaotic behavior of plasma oscillations governed by a modified Duffing equation is studied. The plasma oscillations are described by a nonlinear differential equation of the form x + w 0 2 x + βx 2 + αx 3 = 0 which is similar to a Duffing equation. By focusing on the quadratic term, which is mainly the term modifying the Duffing equation, the harmonic balance method and the fourth order Runge-Kutta algorithm are used to derive regular and chaotic motions respectively. A strong chaotic behavior exhibited by the system in that event when the system is subjected to an external periodic forcing oscillation is reported as β varies. (author)

  9. Actuator Fault Diagnosis in a Boeing 747 Model via Adaptive Modified Two-Stage Kalman Filter

    Directory of Open Access Journals (Sweden)

    Fikret Caliskan

    2014-01-01

    Full Text Available An adaptive modified two-stage linear Kalman filtering algorithm is utilized to identify the loss of control effectiveness and the magnitude of low degree of stuck faults in a closed-loop nonlinear B747 aircraft. Control effectiveness factors and stuck magnitudes are used to quantify faults entering control systems through actuators. Pseudorandom excitation inputs are used to help distinguish partial loss and stuck faults. The partial loss and stuck faults in the stabilizer are isolated and identified successfully.

  10. Improving the Yule-Nielsen modified Neugebauer model by dot surface coverages depending on the ink superposition conditions

    Science.gov (United States)

    Hersch, Roger David; Crete, Frederique

    2005-01-01

    Dot gain is different when dots are printed alone, printed in superposition with one ink or printed in superposition with two inks. In addition, the dot gain may also differ depending on which solid ink the considered halftone layer is superposed. In a previous research project, we developed a model for computing the effective surface coverage of a dot according to its superposition conditions. In the present contribution, we improve the Yule-Nielsen modified Neugebauer model by integrating into it our effective dot surface coverage computation model. Calibration of the reproduction curves mapping nominal to effective surface coverages in every superposition condition is carried out by fitting effective dot surfaces which minimize the sum of square differences between the measured reflection density spectra and reflection density spectra predicted according to the Yule-Nielsen modified Neugebauer model. In order to predict the reflection spectrum of a patch, its known nominal surface coverage values are converted into effective coverage values by weighting the contributions from different reproduction curves according to the weights of the contributing superposition conditions. We analyze the colorimetric prediction improvement brought by our extended dot surface coverage model for clustered-dot offset prints, thermal transfer prints and ink-jet prints. The color differences induced by the differences between measured reflection spectra and reflection spectra predicted according to the new dot surface estimation model are quantified on 729 different cyan, magenta, yellow patches covering the full color gamut. As a reference, these differences are also computed for the classical Yule-Nielsen modified spectral Neugebauer model incorporating a single halftone reproduction curve for each ink. Taking into account dot surface coverages according to different superposition conditions considerably improves the predictions of the Yule-Nielsen modified Neugebauer model. In

  11. A new multiscale model to describe a modified Hall-Petch relation at different scales for nano and micro materials

    Science.gov (United States)

    Fadhil, Sadeem Abbas; Alrawi, Aoday Hashim; Azeez, Jazeel H.; Hassan, Mohsen A.

    2018-04-01

    In the present work, a multiscale model is presented and used to modify the Hall-Petch relation for different scales from nano to micro. The modified Hall-Petch relation is derived from a multiscale equation that determines the cohesive energy between the atoms and their neighboring grains. This brings with it a new term that was originally ignored even in the atomistic models. The new term makes it easy to combine all other effects to derive one modified equation for the Hall-Petch relation that works for all scales together, without the need to divide the scales into two scales, each scale with a different equation, as it is usually done in other works. Due to that, applying the new relation does not require a previous knowledge of the grain size distribution. This makes the new derived relation more consistent and easier to be applied for all scales. The new relation is used to fit the data for Copper and Nickel and it is applied well for the whole range of grain sizes from nano to micro scales.

  12. A Modified Feature Selection and Artificial Neural Network-Based Day-Ahead Load Forecasting Model for a Smart Grid

    Directory of Open Access Journals (Sweden)

    Ashfaq Ahmad

    2015-12-01

    Full Text Available In the operation of a smart grid (SG, day-ahead load forecasting (DLF is an important task. The SG can enhance the management of its conventional and renewable resources with a more accurate DLF model. However, DLF model development is highly challenging due to the non-linear characteristics of load time series in SGs. In the literature, DLF models do exist; however, these models trade off between execution time and forecast accuracy. The newly-proposed DLF model will be able to accurately predict the load of the next day with a fair enough execution time. Our proposed model consists of three modules; the data preparation module, feature selection and the forecast module. The first module makes the historical load curve compatible with the feature selection module. The second module removes redundant and irrelevant features from the input data. The third module, which consists of an artificial neural network (ANN, predicts future load on the basis of selected features. Moreover, the forecast module uses a sigmoid function for activation and a multi-variate auto-regressive model for weight updating during the training process. Simulations are conducted in MATLAB to validate the performance of our newly-proposed DLF model in terms of accuracy and execution time. Results show that our proposed modified feature selection and modified ANN (m(FS + ANN-based model for SGs is able to capture the non-linearity(ies in the history load curve with 97 . 11 % accuracy. Moreover, this accuracy is achieved at the cost of a fair enough execution time, i.e., we have decreased the average execution time of the existing FS + ANN-based model by 38 . 50 % .

  13. Aerodynamic loads calculation and analysis for large scale wind turbine based on combining BEM modified theory with dynamic stall model

    Energy Technology Data Exchange (ETDEWEB)

    Dai, J.C. [College of Mechanical and Electrical Engineering, Central South University, Changsha (China); School of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan (China); Hu, Y.P.; Liu, D.S. [School of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan (China); Long, X. [Hara XEMC Windpower Co., Ltd., Xiangtan (China)

    2011-03-15

    The aerodynamic loads for MW scale horizontal-axis wind turbines are calculated and analyzed in the established coordinate systems which are used to describe the wind turbine. In this paper, the blade element momentum (BEM) theory is employed and some corrections, such as Prandtl and Buhl models, are carried out. Based on the B-L semi-empirical dynamic stall (DS) model, a new modified DS model for NACA63-4xx airfoil is adopted. Then, by combing BEM modified theory with DS model, a set of calculation method of aerodynamic loads for large scale wind turbines is proposed, in which some influence factors such as wind shear, tower, tower and blade vibration are considered. The research results show that the presented dynamic stall model is good enough for engineering purpose; the aerodynamic loads are influenced by many factors such as tower shadow, wind shear, dynamic stall, tower and blade vibration, etc, with different degree; the single blade endures periodical changing loads but the variations of the rotor shaft power caused by the total aerodynamic torque in edgewise direction are very small. The presented study approach of aerodynamic loads calculation and analysis is of the university, and helpful for thorough research of loads reduction on large scale wind turbines. (author)

  14. Heterotopic expression of class B floral homeotic genes supports a modified ABC model for tulip (Tulipa gesneriana).

    Science.gov (United States)

    Kanno, Akira; Saeki, Hiroshi; Kameya, Toshiaki; Saedler, Heinz; Theissen, Günter

    2003-07-01

    In higher eudicotyledonous angiosperms the floral organs are typically arranged in four different whorls, containing sepals, petals, stamens and carpels. According to the ABC model, the identity of these organs is specified by floral homeotic genes of class A, A+B, B+C and C, respectively. In contrast to the sepal and petal whorls of eudicots, the perianths of many plants from the Liliaceae family have two outer whorls of almost identical petaloid organs, called tepals. To explain the Liliaceae flower morphology, van Tunen et al. (1993) proposed a modified ABC model, exemplified with tulip. According to this model, class B genes are not only expressed in whorls 2 and 3, but also in whorl 1. Thus the organs of both whorls 1 and 2 express class A plus class B genes and, therefore, get the same petaloid identity. To test this modified ABC model we have cloned and characterized putative class B genes from tulip. Two DEF- and one GLO-like gene were identified, named TGDEFA, TGDEFB and TGGLO. Northern hybridization analysis showed that all of these genes are expressed in whorls 1, 2 and 3 (outer and inner tepals and stamens), thus corroborating the modified ABC model. In addition, these experiments demonstrated that TGGLO is also weakly expressed in carpels, leaves, stems and bracts. Gel retardation assays revealed that TGGLO alone binds to DNA as a homodimer. In contrast, TGDEFA and TGDEFB cannot homodimerize, but make heterodimers with PI. Homodimerization of GLO-like protein has also been reported for lily, suggesting that this phenomenon is conserved within Liliaceae plants or even monocot species.

  15. Modified HWBI Model(s) Linking Service Flows to Well-Being Endpoints: Accounting for Environmental Quality

    Science.gov (United States)

    This report describes an approach for modifying ORD’s Human Well-Being Index (HWBI) to increase its utility by introducing a composite index developed independently of the HWBI effort. Using ORD’s Environmental Quality Index (EQI), this research examines the potential...

  16. The analysis and application of a new hybrid pollutants forecasting model using modified Kolmogorov-Zurbenko filter.

    Science.gov (United States)

    Li, Peizhi; Wang, Yong; Dong, Qingli

    2017-04-01

    Cities in China suffer from severe smog and haze, and a forecasting system with high accuracy is of great importance to foresee the concentrations of the airborne particles. Compared with chemical transport models, the growing artificial intelligence models can simulate nonlinearities and interactive relationships and getting more accurate results. In this paper, the Kolmogorov-Zurbenko (KZ) filter is modified and firstly applied to construct the model using an artificial intelligence method. The concentration of inhalable particles and fine particulate matter in Dalian are used to analyze the filtered components and test the forecasting accuracy. Besides, an extended experiment is made by implementing a comprehensive comparison and a stability test using data in three other cities in China. Results testify the excellent performance of the developed hybrid models, which can be utilized to better understand the temporal features of pollutants and to perform a better air pollution control and management. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Non centered minor hysteresis loops evaluation based on exponential parameters transforms of the modified inverse Jiles–Atherton model

    International Nuclear Information System (INIS)

    Hamimid, M.; Mimoune, S.M.; Feliachi, M.; Atallah, K.

    2014-01-01

    In this present work, a non centered minor hysteresis loops evaluation is performed using the exponential transforms (ET) of the modified inverse Jiles–Atherton model parameters. This model improves the non centered minor hysteresis loops representation. The parameters of the non centered minor hysteresis loops are obtained from exponential expressions related to the major ones. The parameters of minor loops are obtained by identification using the stochastic optimization method “simulated annealing”. The four parameters of JA model (a,α, k and c) obtained by this transformation are applied only in both ascending and descending branches of the non centered minor hysteresis loops while the major ones are applied to the rest of the cycle. This proposal greatly improves both branches and consequently the minor loops. To validate this model, calculated non-centered minor hysteresis loops are compared with measured ones and good agreements are obtained

  18. Evaluating the performance of the Electron Density Assimilative Model (EDAM) in the Western European sector using modified Taylor diagrams

    Science.gov (United States)

    Jackson-Booth, N.; Parker, J.; Pryse, S. E.; Buckland, R.

    2017-12-01

    The Electron Density Assimilative Model (EDAM) is an ionospheric model that assimilates data sources into a background model, currently provided by IRI2007, to generate a global, or regional, 3D representation of the ionospheric electron density. In this study, slant total electron content (sTEC) between GPS satellites and 43 ground receivers in Europe were assimilated into EDAM to model the ionospheric electron density over western Europe. For the evaluation of the model an additional ground receiver (the truth station) was considered, which was not used in the assimilation process. Slant total electron contents for this station were calculated through the EDAM model along satellite-to-receiver paths corresponding to those of the observations made by the receiver. The modelled and observed sTEC were compared for each satellite and every day, between September 2002 and August 2003. For the comparison standard deviations of the modelled and observed sTEC were determined. These were used in modified Taylor Diagrams to display the mean-removed rms difference between the model and observations, the correlation between the two data sets and the bias of the modelled data. Taylor diagrams were obtained for the entire year, and each season and month. Results of the comparisons are presented and discussed, with a specific interest in times that show increased rms differences and decreased correlations between the data sets. The effect of the satellite calibration biases on the results are also considered.

  19. Modifying the affective behavior of preschoolers with autism using in-vivo or video modeling and reinforcement contingencies.

    Science.gov (United States)

    Gena, Angeliki; Couloura, Sophia; Kymissis, Effie

    2005-10-01

    The purpose of this study was to modify the affective behavior of three preschoolers with autism in home settings and in the context of play activities, and to compare the effects of video modeling to the effects of in-vivo modeling in teaching these children contextually appropriate affective responses. A multiple-baseline design across subjects, with a return to baseline condition, was used to assess the effects of treatment that consisted of reinforcement, video modeling, in-vivo modeling, and prompting. During training trials, reinforcement in the form of verbal praise and tokens was delivered contingent upon appropriate affective responding. Error correction procedures differed for each treatment condition. In the in-vivo modeling condition, the therapist used modeling and verbal prompting. In the video modeling condition, video segments of a peer modeling the correct response and verbal prompting by the therapist were used as corrective procedures. Participants received treatment in three categories of affective behavior--sympathy, appreciation, and disapproval--and were presented with a total of 140 different scenarios. The study demonstrated that both treatments--video modeling and in-vivo modeling--systematically increased appropriate affective responding in all response categories for the three participants. Additionally, treatment effects generalized across responses to untrained scenarios, the child's mother, new therapists, and time.

  20. Measurement of infinite dilution activity coefficient and application of modified ASOG model for solvent-polymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Choi, B.; Choi, J. [Kwangwoon University, Seoul (Korea, Republic of); Tochigi, K.; Kojima, K. [Nihon University, Tokyo (Japan)

    1996-04-20

    A gas chromatographic method was used in order to measure vapor-liquid equilibria for solvent (1)-polymer (2) systems in which the polymers were polystyrene, poly(a-methyl) styrene and the advents were benzene toluene cyclohexane methylisobutylketone, ethylacetate, and vinylacetate. The activity coefficients of solvents for solvent (1)-polymer (2) systems were measured at infinite dilution and the modified ASOG (Analytical Solution of Group) model was suggested to describe vapor-liquid equilibria of those systems within a range of temperatures 423.15K through 498.15K. The model consists of the original ASOG and the free volume term. An external degree of freedom in the free volume term empirically became to a C1={alpha}+{beta}/T as a function of temperature. Each tern in the modified ASOG model is based on the weight fraction. The external degree of freedom in the model was estimated by experimental data within a range of temperatures. As a result of doing it the infinite dilution activity coefficients calculated were agreed with the experimental data within an error of 0.1%. 27 refs., 3 figs., 7 tabs.

  1. Computational issues and applications of line-elements to model subsurface flow governed by the modified Helmholtz equation

    Science.gov (United States)

    Bakker, Mark; Kuhlman, Kristopher L.

    2011-09-01

    Two new approaches are presented for the accurate computation of the potential due to line elements that satisfy the modified Helmholtz equation with complex parameters. The first approach is based on fundamental solutions in elliptical coordinates and results in products of Mathieu functions. The second approach is based on the integration of modified Bessel functions. Both approaches allow evaluation of the potential at any distance from the element. The computational approaches are applied to model transient flow with the Laplace transform analytic element method. The Laplace domain solution is computed using a combination of point elements and the presented line elements. The time domain solution is obtained through a numerical inversion. Two applications are presented to transient flow fields, which could not be modeled with the Laplace transform analytic element method prior to this work. The first application concerns transient single-aquifer flow to wells near impermeable walls modeled with line-doublets. The second application concerns transient two-aquifer flow to a well near a stream modeled with line-sinks.

  2. Improvement in the Modeled Representation of North American Monsoon Precipitation Using a Modified Kain–Fritsch Convective Parameterization Scheme

    KAUST Repository

    Luong, Thang

    2018-01-22

    A commonly noted problem in the simulation of warm season convection in the North American monsoon region has been the inability of atmospheric models at the meso-β scales (10 s to 100 s of kilometers) to simulate organized convection, principally mesoscale convective systems. With the use of convective parameterization, high precipitation biases in model simulations are typically observed over the peaks of mountain ranges. To address this issue, the Kain–Fritsch (KF) cumulus parameterization scheme has been modified with new diagnostic equations to compute the updraft velocity, the convective available potential energy closure assumption, and the convective trigger function. The scheme has been adapted for use in the Weather Research and Forecasting (WRF). A numerical weather prediction-type simulation is conducted for the North American Monsoon Experiment Intensive Observing Period 2 and a regional climate simulation is performed, by dynamically downscaling. In both of these applications, there are notable improvements in the WRF model-simulated precipitation due to the better representation of organized, propagating convection. The use of the modified KF scheme for atmospheric model simulations may provide a more computationally economical alternative to improve the representation of organized convection, as compared to convective-permitting simulations at the kilometer scale or a super-parameterization approach.

  3. The modeling and simulation of thermal based modified solid oxide fuel cell (SOFC for grid-connected systems

    Directory of Open Access Journals (Sweden)

    Ayetül Gelen

    2015-05-01

    Full Text Available This paper presents a thermal based modified dynamic model of a Solid Oxide Fuel Cell (SOFC for grid-connected systems. The proposed fuel cell model involves ohmic, activation and concentration voltage losses, thermal dynamics, methanol reformer, fuel utilization factor and power limiting module. A power conditioning unit (PCU, which consists of a DC-DC boost converter and a DC-AC voltage-source inverter (VSI, their controller, transformer and filter, is designed for grid-connected systems. The voltage-source inverter with six Insulated Gate Bipolar Transistor (IGBT switches inverts the DC voltage that comes from the converter into a sinusoidal voltage synchronized with the grid. The simulations and modeling of the system are developed on Matlab/Simulink environment. The performance of SOFC with converter is examined under step and random load conditions. The simulation results show that the designed boost converter for the proposed thermal based modified SOFC model has fairly followed different DC load variations. Finally, the AC bus of 400 Volt and 50 Hz is connected to a single-machine infinite bus (SMIB through a transmission line. The real and reactive power managements of the inverter are analyzed by an infinite bus system. Thus, the desired nominal values are properly obtained by means of the inverter controller.

  4. Risk analysis of bioprocesses based on genetically modified bacteria. Pathway and exposure modeling

    Energy Technology Data Exchange (ETDEWEB)

    Rein, A.; Bittens, M. [Tuebingen Univ. (Germany). Zentrum fuer Angewandte Geowissenschaften

    2003-07-01

    For soils contaminated with polychlorinated biphenyls (PCBs), a plant-microorganism system for in situ - bioremediation has been developed. It consists of genetically modified microorganisms (GMOs) in conjunction with plant roots. The GMOs are Pseudomonas fluorescens strains which are genetically engineered to degrade PCB congeners in situ. Their metabolism requires root exudates and is therefore tightly coupled to plant rhizospheres. Compared to wild type organisms, the genetically modified bacteria develop a specificity to PCB as a substrate and therefore foster biodegradation in a more efficient way. To evaluate the efficiency and impact of this bioremediation system for potential field application, lysimeter tests are carried out. The lysimeters are filled with contaminated soil from a PCB release site in Denmark and planted with GMO inoculated plants. On the basis of these experiments, a detailed risk analysis is carried out to obtain conclusions to field-conditions (potential deliberate GMO-release). A qualitative and quantitative assessment of actual or potential effects is performed, addressing transport, fate and exposure of PCBs, GMOs and specific degradation products in different environmental compartments. (orig.)

  5. Application of omics technologies for environmental risk assessment of genetically modified plants : arabidopsis and modified defence mechanisms as a model study

    NARCIS (Netherlands)

    Houshyani Hassanzadeh, B.

    2012-01-01

    As a result of rapid biotechnological developments in the past century, genetically modified (GM) crops were developed and introduced for field application. Despite the advantages of these crops and the professional marketing policies, people also started questioning the safety of GM products

  6. Modified Shrinking Core Model for Atomic Layer Deposition of TiO2 on Porous Alumina with Ultrahigh Aspect Ratio

    International Nuclear Information System (INIS)

    Park, Inhye; Leem, Jina; Lee, Hooyong; Min, Yosep

    2013-01-01

    When atomic layer deposition (ALD) is performed on a porous material by using an organometallic precursor, minimum exposure time of the precursor for complete coverage becomes much longer since the ALD is limited by Knudsen diffusion in the pores. In the previous report by Min et al. (Ref. 23), shrinking core model (SCM) was proposed to predict the minimum exposure time of diethylzinc for ZnO ALD on a porous cylindrical alumina monolith. According to the SCM, the minimum exposure time of the precursor is influenced by volumetric density of adsorption sites, effective diffusion coefficient, precursor concentration in gas phase and size of the porous monolith. Here we modify the SCM in order to consider undesirable adsorption of byproduct molecules. TiO 2 ALD was performed on the cylindrical alumina monolith by using titanium tetrachloride (TiCl 4 ) and water. We observed that the byproduct (i. e., HCl) of TiO 2 ALD can chemically adsorb on adsorption sites, unlike the behavior of the byproduct (i. e., ethane) of ZnO ALD. Consequently, the minimum exposure time of TiCl 4 (∼16 min) was significantly much shorter than that (∼71 min) of DEZ. The predicted minimum exposure time by the modified SCM well agrees with the observed time. In addition, the modified SCM gives an effective diffusion coefficient of TiCl 4 of ∼1.78 Χ 10 -2 cm 2 /s in the porous alumina monolith

  7. Unified cosmic history in modified gravity: From F(R) theory to Lorentz non-invariant models

    Science.gov (United States)

    Nojiri, Shin'Ichi; Odintsov, Sergei D.

    2011-08-01

    The classical generalization of general relativity is considered as the gravitational alternative for a unified description of the early-time inflation with late-time cosmic acceleration. The structure and cosmological properties of a number of modified theories, including traditional F(R) and Hořava-Lifshitz F(R) gravity, scalar-tensor theory, string-inspired and Gauss-Bonnet theory, non-local gravity, non-minimally coupled models, and power-counting renormalizable covariant gravity are discussed. Different representations of and relations between such theories are investigated. It is shown that some versions of the above theories may be consistent with local tests and may provide a qualitatively reasonable unified description of inflation with the dark energy epoch. The cosmological reconstruction of different modified gravities is provided in great detail. It is demonstrated that eventually any given universe evolution may be reconstructed for the theories under consideration, and the explicit reconstruction is applied to an accelerating spatially flat Friedmann-Robertson-Walker (FRW) universe. Special attention is paid to Lagrange multiplier constrained and conventional F(R) gravities, for latter F(R) theory, the effective ΛCDM era and phantom divide crossing acceleration are obtained. The occurrences of the Big Rip and other finite-time future singularities in modified gravity are reviewed along with their solutions via the addition of higher-derivative gravitational invariants.

  8. A Mixture Model of Consumers' Intended Purchase Decisions for Genetically Modified Foods

    OpenAIRE

    Kristine M. Grimsrud; Robert P. Berrens; Ron C. Mittelhammer

    2006-01-01

    A finite probability mixture model is used to analyze the existence of multiple market segments for a pre-market good. The approach has at least two principal benefits. First, the model is capable of identifying likely market segments and their differentiating characteristics. Second, the model can be used to estimate the discount different consumer groups require to purchase the good. The model is illustrated using stated preference survey data collected on consumer responses to the potentia...

  9. Association between floods and infectious diarrhea and their effect modifiers in Hunan province, China: A two-stage model.

    Science.gov (United States)

    Liu, Zhidong; Zhang, Feifei; Zhang, Ying; Li, Jing; Liu, Xuena; Ding, Guoyong; Zhang, Caixia; Liu, Qiyong; Jiang, Baofa

    2018-06-01

    Understanding the potential links between floods and infectious diarrhea is important under the context of climate change. However, little is known about the risk of infectious diarrhea after floods and what factors could modify these effects in China. This study aims to quantitatively examine the relationship between floods and infectious diarrhea and their effect modifiers. Weekly number of infectious diarrhea cases from 2004 to 2011 during flood season in Hunan province were supplied by the National Notifiable Disease Surveillance System. Flood and meteorological data over the same period were obtained. A two-stage model was used to estimate a provincial average association and their effect modifiers between floods and infectious diarrhea, accounting for other confounders. A total of 134,571 cases of infectious diarrhea were notified from 2004 to 2011. After controlling for seasonality, long-term trends, and meteorological factors, floods were significantly associated with infectious diarrhea in the provincial level with a cumulative RR of 1.22 (95% CI: 1.05, 1.43) with a lagged effect of 0-1 week. Geographic locations and economic levels were identified as effect modifiers, with a higher impact of floods on infectious diarrhea in the western and regions with a low economic level of Hunan. Our study provides strong evidence of a positive association between floods and infectious diarrhea in the study area. Local control strategies for public health should be taken in time to prevent and reduce the risk of infectious diarrhea after floods, especially for the vulnerable regions identified. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Noether symmetries of a modified model in teleparallel gravity and a new approach for exact solutions

    Energy Technology Data Exchange (ETDEWEB)

    Tajahmad, Behzad [University of Tabriz, Faculty of Physics, Tabriz (Iran, Islamic Republic of)

    2017-04-15

    In this paper, we present the Noether symmetries of flat FRW spacetime in the context of a new action in teleparallel gravity which we construct based on the f(R) version. This modified action contains a coupling between the scalar field potential and magnetism. Also, we introduce an innovative approach, the beyond Noether symmetry (B.N.S.) approach, for exact solutions which carry more conserved currents than the Noether approach. By data analysis of the exact solutions, obtained from the Noether approach, late-time acceleration and phase crossing are realized, and some deep connections with observational data such as the age of the universe, the present value of the scale factor as well as the state and deceleration parameters are observed. In the B.N.S. approach, we consider the dark energy dominated era. (orig.)

  11. A Modified Fatigue Damage Model for High-Cycle Fatigue Life Prediction

    Directory of Open Access Journals (Sweden)

    Meng Wang

    2016-01-01

    Full Text Available Based on the assumption of quasibrittle failure under high-cycle fatigue for the metal material, the damage constitutive equation and the modified damage evolution equation are obtained with continuum damage mechanics. Then, finite element method (FEM is used to describe the failure process of metal material. The increment of specimen’s life and damage state can be researched using damage mechanics-FEM. Finally, the lifetime of the specimen is got at the given stress level. The damage mechanics-FEM is inserted into ABAQUS with subroutine USDFLD and the Python language is used to simulate the fatigue process of titanium alloy specimens. The simulation results have a good agreement with the testing results under constant amplitude loading, which proves the accuracy of the method.

  12. Computational modeling of latent-heat-storage in PCM modified interior plaster

    Energy Technology Data Exchange (ETDEWEB)

    Fořt, Jan; Maděra, Jiří; Trník, Anton; Pavlíková, Milena; Pavlík, Zbyšek [Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague (Czech Republic)

    2016-06-08

    The latent heat storage systems represent a promising way for decrease of buildings energy consumption with respect to the sustainable development principles of building industry. The presented paper is focused on the evaluation of the effect of PCM incorporation on thermal performance of cement-lime plasters. For basic characterization of the developed materials, matrix density, bulk density, and total open porosity are measured. Thermal conductivity is accessed by transient impulse method. DSC analysis is used for the identification of phase change temperature during the heating and cooling process. Using DSC data, the temperature dependent specific heat capacity is calculated. On the basis of the experiments performed, the supposed improvement of the energy efficiency of characteristic building envelope system where the designed plasters are likely to be used is evaluated by a computational analysis. Obtained experimental and computational results show a potential of PCM modified plasters for improvement of thermal stability of buildings and moderation of interior climate.

  13. Noether symmetries of a modified model in teleparallel gravity and a new approach for exact solutions

    International Nuclear Information System (INIS)

    Tajahmad, Behzad

    2017-01-01

    In this paper, we present the Noether symmetries of flat FRW spacetime in the context of a new action in teleparallel gravity which we construct based on the f(R) version. This modified action contains a coupling between the scalar field potential and magnetism. Also, we introduce an innovative approach, the beyond Noether symmetry (B.N.S.) approach, for exact solutions which carry more conserved currents than the Noether approach. By data analysis of the exact solutions, obtained from the Noether approach, late-time acceleration and phase crossing are realized, and some deep connections with observational data such as the age of the universe, the present value of the scale factor as well as the state and deceleration parameters are observed. In the B.N.S. approach, we consider the dark energy dominated era. (orig.)

  14. Additivity of statistical moments in the exponentially modified Gaussian model of chromatography

    International Nuclear Information System (INIS)

    Howerton, Samuel B.; Lee Chomin; McGuffin, Victoria L.

    2002-01-01

    A homologous series of saturated fatty acids ranging from C 10 to C 22 was separated by reversed-phase capillary liquid chromatography. The resultant zone profiles were found to be fit best by an exponentially modified Gaussian (EMG) function. To compare the EMG function and statistical moments for the analysis of the experimental zone profiles, a series of simulated profiles was generated by using fixed values for retention time and different values for the symmetrical (σ) and asymmetrical (τ) contributions to the variance. The simulated profiles were modified with respect to the integration limits, the number of points, and the signal-to-noise ratio. After modification, each profile was analyzed by using statistical moments and an iteratively fit EMG equation. These data indicate that the statistical moment method is much more susceptible to error when the degree of asymmetry is large, when the integration limits are inappropriately chosen, when the number of points is small, and when the signal-to-noise ratio is small. The experimental zone profiles were then analyzed by using the statistical moment and EMG methods. Although care was taken to minimize the sources of error discussed above, significant differences were found between the two methods. The differences in the second moment suggest that the symmetrical and asymmetrical contributions to broadening in the experimental zone profiles are not independent. As a consequence, the second moment is not equal to the sum of σ 2 and τ 2 , as is commonly assumed. This observation has important implications for the elucidation of thermodynamic and kinetic information from chromatographic zone profiles

  15. Minimal Regge model for meson--baryon scattering: duality, SU(3) and phase-modified absorptive cuts

    International Nuclear Information System (INIS)

    Egli, S.E.

    1975-10-01

    A model is presented which incorporates economically all of the modifications to simple SU(3)-symmetric dual Regge pole theory which are required by existing data on 0 -1 / 2 + → -1 / 2 + processes. The basic assumptions are no-exotics duality, minimally broken SU(3) symmetry, and absorptive Regge cuts phase-modified by the Ringland prescription. First it is described qualitatively how these assumptions suffice for the description of all measured reactions, and then the results of a detailed fit to 1987 data points are presented for 18 different reactions. (auth)

  16. Biosorption of Cu (II onto chemically modified waste mycelium of Aspergillus awamori: Equilibrium, kinetics and modeling studies

    Directory of Open Access Journals (Sweden)

    ZDRAVKA VELKOVA

    2012-01-01

    Full Text Available The biosorption potential of chemically modified waste mycelium of industrial xylanase-producing strain Aspergillus awamori for Cu (II removal from aqueous solutions was evaluated. The influence of pH, contact time and initial Cu (II concentration on the removal efficiency was evaluated. Maximum biosorption capacity was reached by sodium hydroxide treated waste fungal mycelium at pH 5.0. The Langmuir adsorption equation matched very well the adsorption equilibrium data in the studied conditions. The process kinetic followed the pseudo-firs order model.

  17. NASA-modified precipitation products to improve USEPA nonpoint source water quality modeling for the Chesapeake Bay.

    Science.gov (United States)

    Nigro, Joseph; Toll, David; Partington, Ed; Ni-Meister, Wenge; Lee, Shihyan; Gutierrez-Magness, Angelica; Engman, Ted; Arsenault, Kristi

    2010-01-01

    The USEPA has estimated that over 20,000 water bodies within the United States do not meet water quality standards. One of the regulations in the Clean Water Act of 1972 requires states to monitor the total maximum daily load, or the amount of pollution that can be carried by a water body before it is determined to be "polluted," for any watershed in the United States (Copeland, 2005). In response to this mandate, the USEPA developed Better Assessment Science Integrating Nonpoint Sources (BASINS) as a decision support tool for assessing pollution and to guide the decision-making process for improving water quality. One of the models in BASINS, the Hydrological Simulation Program-Fortran (HSPF), computes continuous streamflow rates and pollutant concentration at each basin outlet. By design, precipitation and other meteorological data from weather stations serve as standard model input. In practice, these stations may be unable to capture the spatial heterogeneity of precipitation events, especially if they are few and far between. An attempt was made to resolve this issue by substituting station data with NASA-modified/NOAA precipitation data. Using these data within HSPF, streamflow was calculated for seven watersheds in the Chesapeake Bay Basin during low flow periods, convective storm periods, and annual flows. In almost every case, the modeling performance of HSPF increased when using the NASA-modified precipitation data, resulting in better streamflow statistics and, potentially, in improved water quality assessment.

  18. Improving the food waste composting facilities site selection for sustainable development using a hybrid modified MADM model.

    Science.gov (United States)

    Liu, Kung-Ming; Lin, Sheng-Hau; Hsieh, Jing-Chzi; Tzeng, Gwo-Hshiung

    2018-05-01

    With the growth of population and the development of urbanization, waste management has always been a critical global issue. Recently, more and more countries have found that food waste constitutes the majority of municipal waste, if they are disposed of properly, will bring more benefits in sustainable development. Regarding the issue of selecting and improving the location to make the disposal facility towards achieving the aspiration level for sustainable development, since it involves multiple and complicated interaction factors about environment, society, and economy which have to be considered properly in the decision-making process of mutual influence relationship. It is basically a multiple attribute decision making (MADM) issue, a difficult problem which has been obsessing the governments of many countries is widely studied and discussed. This study uses the new hybrid modified MADM model, as follows, first to build an influential network relation map (INRM) via DEMATEL technique, next to confirm the influential weightings via DANP (DEMATEL-based ANP), and then to construct a decision-making model via a hybrid modified VIKOR method to improve and select the location for remaining the best disposal facilities. Finally, an empirical case study is illustrated to demonstrate that the proposed model can be effective and useful. In finding the process of decision making, environmental pollution is the main concern of many people in the area, but actually it is the resistance by the general public that has to be considered with first priority. Copyright © 2018. Published by Elsevier Ltd.

  19. A density model based on the Modified Quasichemical Model and applied to the (NaCl + KCl + ZnCl2) liquid

    International Nuclear Information System (INIS)

    Ouzilleau, Philippe; Robelin, Christian; Chartrand, Patrice

    2012-01-01

    Highlights: ► A model for the density of multicomponent inorganic liquids. ► The density model is based on the Modified Quasichemical Model. ► Application to the (NaCl + KCl + ZnCl 2 ) ternary liquid. ► A Kohler–Toop-like asymmetric interpolation method was used. - Abstract: A theoretical model for the density of multicomponent inorganic liquids based on the Modified Quasichemical Model has been presented previously. By introducing in the Gibbs free energy of the liquid phase temperature-dependent molar volume expressions for the pure components and pressure-dependent excess parameters for the binary (and sometimes higher-order) interactions, it is possible to reproduce, and eventually predict, the molar volume and the density of the multicomponent liquid phase using standard interpolation methods. In the present article, this density model is applied to the (NaCl + KCl + ZnCl 2 ) ternary liquid and a Kohler–Toop-like asymmetric interpolation method is used. All available density data for the (NaCl + KCl + ZnCl 2 ) liquid were collected and critically evaluated, and optimized pressure-dependent model parameters have been found. This new volumetric model can be used with Gibbs free energy minimization software, to calculate the molar volume and the density of (NaCl + KCl + ZnCl 2 ) ternary melts.

  20. Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Jhih-Hong Lin

    2016-08-01

    Full Text Available Magnetic shape memory (MSM alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

  1. Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control.

    Science.gov (United States)

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2016-08-25

    Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

  2. PENGEMBANGAN MODEL PEMBELAJARAN MODIFIED STUDENT TEAMS ACHIEVEMENT DIVISION (MSTAD DALAM MENINGKATKAN HASIL BELAJAR SISWA PADA PEMBELAJARAN STRUKTUR ALJABAR

    Directory of Open Access Journals (Sweden)

    Kartika Sari

    2015-09-01

    Full Text Available The application of Students Team Achievement Division (STAD model in learning algebra structure indicated that the model is slow on detecting an error in understanding the material and it also need more time to completely delivered all of the course’s material. Therefore, in this study STAD was modified into Modified Students Teams Achievement Division (MSTAD. MSTAD development was carried out through three stages: developing new ideas based on previous research, developing results, and conducting trials. Trials  were performed  on  students taking  Algebra Structure 1  course in  2013/2014  and  2014/2015 academic year in one of the universities in Bali. Results showed that error in understanding the material was detected early, and every material was delivered on time. Statistical analysis also showed that class where MSTAD was applied achieve significantly better learning outcomes compared to STAD class and conventional class for 2013/2014 academic year (t= -9,339 < t0,05(41 = -2,702 as well as 2014/2015 academic year (Z0,5(1-0,01=0,4950 = 2,57.   ABSTRAK Penerapan   model   Student Team Achievement Division (STAD dalam pembelajaran Struktur Aljabar menunjukkan bahwa kesalahan dalam memahami materi lambat terdeteksi dan perlu tambahan waktu untuk menyelesaikan semua materi. Oleh karena itu, dalam penelitian ini dikembangkan modifikasi model STAD yaitu model pembelajaran Modified Student Teams Achievement Division (MSTAD.Pengembangan dilakukan melalui tiga tahap yaitu mengembangkan ide baru berdasarkan penelitian sebelumnya, mengem- bangkan hasil, dan melaksanakan uji coba. Uji coba dilakukan pada mahasiswa yang mengambil mata kuliah Struktur Aljabar 1 pada Tahun Ajaran 2013/2014 dan 2014/2015 di Jurusan Matematika salah satu Universitas di Bali. Hasil ujicoba menunjukkan bahwa kesalahan dalam memahami materi dapat terdeteksi lebih awal dan materi juga dapat diselesaikan tepat waktu. Hasil analisis statistik juga menunjukkan

  3. Modeling of boldine alkaloid adsorption onto pure and propyl-sulfonic acid-modified mesoporous silicas. A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Geszke-Moritz, Małgorzata, E-mail: Malgorzata.Geszke-Moritz@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Moritz, Michał, E-mail: michal.moritz@put.poznan.pl [Poznan University of Technology, Faculty of Chemical Technology, Institute of Chemistry and Technical Electrochemistry, Berdychowo 4, 60-965 Poznań (Poland)

    2016-12-01

    The present study deals with the adsorption of boldine onto pure and propyl-sulfonic acid-functionalized SBA-15, SBA-16 and mesocellular foam (MCF) materials. Siliceous adsorbents were characterized by nitrogen sorption analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis. The equilibrium adsorption data were analyzed using the Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherms. Moreover, the Dubinin-Radushkevich and Dubinin-Astakhov isotherm models based on the Polanyi adsorption potential were employed. The latter was calculated using two alternative formulas including solubility-normalized (S-model) and empirical C-model. In order to find the best-fit isotherm, both linear regression and nonlinear fitting analysis were carried out. The Dubinin-Astakhov (S-model) isotherm revealed the best fit to the experimental points for adsorption of boldine onto pure mesoporous materials using both linear and nonlinear fitting analysis. Meanwhile, the process of boldine sorption onto modified silicas was described the best by the Langmuir and Temkin isotherms using linear regression and nonlinear fitting analysis, respectively. The values of adsorption energy (below 8 kJ/mol) indicate the physical nature of boldine adsorption onto unmodified silicas whereas the ionic interactions seem to be the main force of alkaloid adsorption onto functionalized sorbents (energy of adsorption above 8 kJ/mol). - Graphical abstract: Modeling of boldine adsorption onto unmodified and propyl-sulfonic acid-modified mesoporous adsorbents. - Highlights: • The process of boldine adsorption onto SBA-15, SBA-16 and MCF silicas was examined. • Siliceous adsorbents were functionalized with propyl-sulfonic acid groups. • The equilibrium adsorption data were analyzed using several isotherm models. • Both linear regression and nonlinear fitting analysis were carried out.

  4. Development of Modified Incompressible Ideal Gas Model for Natural Draft Cooling Tower Flow Simulation

    Science.gov (United States)

    Hyhlík, Tomáš

    2018-06-01

    The article deals with the development of incompressible ideal gas like model, which can be used as a part of mathematical model describing natural draft wet-cooling tower flow, heat and mass transfer. It is shown, based on the results of a complex mathematical model of natural draft wet-cooling tower flow, that behaviour of pressure, temperature and density is very similar to the case of hydrostatics of moist air, where heat and mass transfer in the fill zone must be taken into account. The behaviour inside the cooling tower is documented using density, pressure and temperature distributions. The proposed equation for the density is based on the same idea like the incompressible ideal gas model, which is only dependent on temperature, specific humidity and in this case on elevation. It is shown that normalized density difference of the density based on proposed model and density based on the nonsimplified model is in the order of 10-4. The classical incompressible ideal gas model, Boussinesq model and generalised Boussinesq model are also tested. These models show deviation in percentages.

  5. Development of Modified Incompressible Ideal Gas Model for Natural Draft Cooling Tower Flow Simulation

    Directory of Open Access Journals (Sweden)

    Hyhlík Tomáš

    2018-01-01

    Full Text Available The article deals with the development of incompressible ideal gas like model, which can be used as a part of mathematical model describing natural draft wet-cooling tower flow, heat and mass transfer. It is shown, based on the results of a complex mathematical model of natural draft wet-cooling tower flow, that behaviour of pressure, temperature and density is very similar to the case of hydrostatics of moist air, where heat and mass transfer in the fill zone must be taken into account. The behaviour inside the cooling tower is documented using density, pressure and temperature distributions. The proposed equation for the density is based on the same idea like the incompressible ideal gas model, which is only dependent on temperature, specific humidity and in this case on elevation. It is shown that normalized density difference of the density based on proposed model and density based on the nonsimplified model is in the order of 10-4. The classical incompressible ideal gas model, Boussinesq model and generalised Boussinesq model are also tested. These models show deviation in percentages.

  6. A new modified resource budget model for nonlinear dynamics in citrus production

    International Nuclear Information System (INIS)

    Ye, Xujun; Sakai, Kenshi

    2016-01-01

    Highlights: • A theoretical modeling and simulation study of the nonlinear dynamics in citrus is conducted. • New leaf growth is incorporated into the model as a major factor responsible for the yield oscillations. • A Ricker-type equation for the relationship between costs for flowering and fruiting is proposed. • A generic form of the resource budget model for the nonlinear dynamics in citrus is obtained. • The new model is tested with experimental data for two citrus trees. - Abstract : Alternate bearing or masting is a general yield variability phenomenon in perennial tree crops. This paper first presents a theoretical modeling and simulation study of the mechanism for this dynamics in citrus, and then provides a test of the proposed models using data from a previous 16-year experiment in a citrus orchard. Our previous studies suggest that the mutual effects between vegetative and reproductive growths caused by resource allocation and budgeting in plant body might be considered as a major factor responsible for the yield oscillations in citrus. Based on the resource budget model proposed by Isagi et al. (J Theor Biol. 1997;187:231-9), we first introduce the new leaf growth as a major energy consumption component into the model. Further, we introduce a nonlinear Ricker-type equation to replace the linear relationship between costs for flowering and fruiting used in Isagi's model. Model simulations demonstrate that the proposed new models can successfully simulate the reproductive behaviors of citrus trees with different fruiting dynamics. These results may enrich the mechanical dynamics in tree crop reproductive models and help us to better understand the dynamics of vegetative-reproductive growth interactions in a real environment.

  7. A Modified Johnson-Cook Model for Sheet Metal Forming at Elevated Temperatures and Its Application for Cooled Stress-Strain Curve and Spring-Back Prediction

    International Nuclear Information System (INIS)

    Duc-Toan, Nguyen; Tien-Long, Banh; Young-Suk, Kim; Dong-Won, Jung

    2011-01-01

    In this study, a modified Johnson-Cook (J-C) model and an innovated method to determine (J-C) material parameters are proposed to predict more correctly stress-strain curve for tensile tests in elevated temperatures. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. As the first verification, an FEM tensile test simulation based on the isotropic hardening model for boron sheet steel at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code, and compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation of cooling process. The modified (J-C) model showed the good agreement between the simulation results and the corresponding experiments. The second investigation was applied for V-bending spring-back prediction of magnesium alloy sheets at elevated temperatures. Here, the combination of proposed J-C model with modified hardening law considering the unusual plastic behaviour for magnesium alloy sheet was adopted for FEM simulation of V-bending spring-back prediction and shown the good comparability with corresponding experiments.

  8. The modified Jeffreys model approach for elasto-viscoplastic thixotropic substances

    Energy Technology Data Exchange (ETDEWEB)

    Azikri de Deus, Hilbeth P., E-mail: azikri@utfpr.edu.br [CERNN-UTFPR/NuMAT-UTFPR, Curitiba, PR (Brazil); Negrão, Cezar O.R.; Franco, Admilson T. [CERNN-UTFPR, Curitiba, PR (Brazil)

    2016-02-05

    In this work, a new constitutive model for thixotropic fluids is proposed via a formal analysis of their functional forms. The constitutive model for thixotropic substances is basically composed by a set of two equations: a constitutive equation based on viscoelastic models and a rate equation (an equation related to the evolution of the micro-structural character of the substance). The constitutive equations, in many works, do not have taken into account in the dynamical principles from which is developed the micro-structural dependence of shear modulus and viscosity. To aim this fault, in the current study a new constitutive model (based on Jeffreys model) is proposed, in coherence with expected behavior for thixotropic fluids. In addition a special emphasis has been given to the structural nature of substances (based on coagulation theory of Smoluchowski) and thermodynamic consistency. The proposed model for thixotropic fluids takes into account a simple isothermal laminar shear flows and some important aspects of that are explored. - Highlights: • A new constitutive model, composed by a constitutive and a rate equations, for thixotropic fluids is proposed. • The constitutive equation takes into account the micro-structural dependence of the shear modulus and viscosity coefficients. • The rate equation is based on Brownian motion (coagulation theory of Smoluchowski) and reptation model. • The thermodynamic consistence of the proposed model is proved too.

  9. Contemporary challenges in applying of the modified model CAPM with country risk premium in emerging economies

    OpenAIRE

    Petrović Dragana

    2017-01-01

    Modern approach in determining the expected return of foreign investors' investments is based on the evaluation investment in capital asset-CAPM (Capital Asset Pricing Model). In order to use the CAPM model for calculating the expected return of foreign investors in growing economies, it is developed the extended model CAPM with the risk premium in the country. This variant of the CAPM model has been used for estimating the cost of capital. This is the expected return on a portfolio of the co...

  10. Development of a modified model of spinal cord ischemia injury by selective ligation of lumbar arteries in rabbits.

    Science.gov (United States)

    Xiao, W; Wen, J; Huang, Y-C; Yu, B-S

    2017-11-01

    Experimental study. The aim of this study is to develop a modified model of spinal cord ischemia in rabbits. Shenzhen Key Laboratory of Spine Surgery, Shenzhen, China. In total, 20 New Zealand rabbits were divided into the following four groups according to the level of ligation of bilateral lumbar arteries: (1) group A, sham group, no ligation, n=5; (2) group B, ligation of bilateral lumbar arteries at three levels (L2-L4, n=5); (3) group C, ligation of bilateral lumbar arteries at four levels (L2-L5, n=5); and (4) group D, ligation of bilateral lumbar arteries at five levels (L1-L5, n=5). The latency of motor-evoked potentials was measured intraoperatively and the modified Tarlov grades were scored, followed by a histological observation of spinal cord, on the seventh day after surgery. All 10 rabbits in Group A and Group B were electrophysiologically, neurologically and histologically normal. In Group C, moderate spinal cord ischemia injury was found in three of five rabbits: they had prolonged latency of motor-evoked potentials and neuronal karyopyknosis in the anterior horn of spinal cord, and the average Tarlov score was 4.2±0.8. In Group D, severe spinal cord ischemia injury was recorded in all the five rabbits: the latency of motor-evoked potential prolonged in one rabbit, whereas the waveform disappeared in four rabbits; loss of neurons and vacuolation of gray matter were seen in spinal cord sections, and the average Tarlov score was 0.6±0.9. Selective ligation of lumbar arteries was a modified method to induce feasible and reproducible model of spinal cord ischemia in rabbits.

  11. Elastic properties of graphene: A pseudo-beam model with modified internal bending moment and its application

    Science.gov (United States)

    Xia, Z. M.; Wang, C. G.; Tan, H. F.

    2018-04-01

    A pseudo-beam model with modified internal bending moment is presented to predict elastic properties of graphene, including the Young's modulus and Poisson's ratio. In order to overcome a drawback in existing molecular structural mechanics models, which only account for pure bending (constant bending moment), the presented model accounts for linear bending moments deduced from the balance equations. Based on this pseudo-beam model, an analytical prediction is accomplished to predict the Young's modulus and Poisson's ratio of graphene based on the equation of the strain energies by using Castigliano second theorem. Then, the elastic properties of graphene are calculated compared with results available in literature, which verifies the feasibility of the pseudo-beam model. Finally, the pseudo-beam model is utilized to study the twisting wrinkling characteristics of annular graphene. Due to modifications of the internal bending moment, the wrinkling behaviors of graphene sheet are predicted accurately. The obtained results show that the pseudo-beam model has a good ability to predict the elastic properties of graphene accurately, especially the out-of-plane deformation behavior.

  12. Verification of Exciton Effects in Organic Solar Cells at Low Temperatures Based on a Modified Numerical Model

    Science.gov (United States)

    Xiong, Chun-Hua; Sun, Jiu-Xun; Wang, Dai-Peng; Dong, Yan

    2018-02-01

    There are many models for researching charge transport in semiconductors and improving their performance. Most of them give good descriptions of the experimental data at room temperature. But it is still an open question which model is correct. In this paper, numerical calculations based on three modified versions of a classical model were made, and compared with experimental data for typical devices at room or low temperatures. Although their results are very similar to each other at room temperatures, only the version considering exciton effects by using a hydrogen-like model can give qualitative descriptions to recent experimental data at low temperatures. Moreover, the mobility was researched in detail by comparing the constant model and temperature dependence model. Then, we found the performance increases with the mobility of each charge carrier type being independent to the mobility of the other one. This paper provides better insight into understanding the physical mechanism of carrier transport in semiconductors, and the results show that exciton effects should be considered in modeling organic solar cells.

  13. A Kinetic Model for Predicting the Relative Humidity in Modified Atmosphere Packaging and Its Application in Lentinula edodes Packages

    Directory of Open Access Journals (Sweden)

    Li-xin Lu

    2013-01-01

    Full Text Available Adjusting and controlling the relative humidity (RH inside package is crucial for ensuring the quality of modified atmosphere packaging (MAP of fresh produce. In this paper, an improved kinetic model for predicting the RH in MAP was developed. The model was based on heat exchange and gases mass transport phenomena across the package, gases heat convection inside the package, and mass and heat balances accounting for the respiration and transpiration behavior of fresh produce. Then the model was applied to predict the RH in MAP of fresh Lentinula edodes (one kind of Chinese mushroom. The model equations were solved numerically using Adams-Moulton method to predict the RH in model packages. In general, the model predictions agreed well with the experimental data, except that the model predictions were slightly high in the initial period. The effect of the initial gas composition on the RH in packages was notable. In MAP of lower oxygen and higher carbon dioxide concentrations, the ascending rate of the RH was reduced, and the RH inside packages was saturated slowly during storage. The influence of the initial gas composition on the temperature inside package was not much notable.

  14. Quantitative estimation of renal function with dynamic contrast-enhanced MRI using a modified two-compartment model.

    Directory of Open Access Journals (Sweden)

    Bin Chen

    Full Text Available To establish a simple two-compartment model for glomerular filtration rate (GFR and renal plasma flow (RPF estimations by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI.A total of eight New Zealand white rabbits were included in DCE-MRI. The two-compartment model was modified with the impulse residue function in this study. First, the reliability of GFR measurement of the proposed model was compared with other published models in Monte Carlo simulation at different noise levels. Then, functional parameters were estimated in six healthy rabbits to test the feasibility of the new model. Moreover, in order to investigate its validity of GFR estimation, two rabbits underwent acute ischemia surgical procedure in unilateral kidney before DCE-MRI, and pixel-wise measurements were implemented to detect the cortical GFR alterations between normal and abnormal kidneys.The lowest variability of GFR and RPF measurements were found in the proposed model in the comparison. Mean GFR was 3.03±1.1 ml/min and mean RPF was 2.64±0.5 ml/g/min in normal animals, which were in good agreement with the published values. Moreover, large GFR decline was found in dysfunction kidneys comparing to the contralateral control group.Results in our study demonstrate that measurement of renal kinetic parameters based on the proposed model is feasible and it has the ability to discriminate GFR changes in healthy and diseased kidneys.

  15. High resolution global flood hazard map from physically-based hydrologic and hydraulic models.

    Science.gov (United States)

    Begnudelli, L.; Kaheil, Y.; McCollum, J.

    2017-12-01

    The global flood map published online at http://www.fmglobal.com/research-and-resources/global-flood-map at 90m resolution is being used worldwide to understand flood risk exposure, exercise certain measures of mitigation, and/or transfer the residual risk financially through flood insurance programs. The modeling system is based on a physically-based hydrologic model to simulate river discharges, and 2D shallow-water hydrodynamic model to simulate inundation. The model can be applied to large-scale flood hazard mapping thanks to several solutions that maximize its efficiency and the use of parallel computing. The hydrologic component of the modeling system is the Hillslope River Routing (HRR) hydrologic model. HRR simulates hydrological processes using a Green-Ampt parameterization, and is calibrated against observed discharge data from several publicly-available datasets. For inundation mapping, we use a 2D Finite-Volume Shallow-Water model with wetting/drying. We introduce here a grid Up-Scaling Technique (UST) for hydraulic modeling to perform simulations at higher resolution at global scale with relatively short computational times. A 30m SRTM is now available worldwide along with higher accuracy and/or resolution local Digital Elevation Models (DEMs) in many countries and regions. UST consists of aggregating computational cells, thus forming a coarser grid, while retaining the topographic information from the original full-resolution mesh. The full-resolution topography is used for building relationships between volume and free surface elevation inside cells and computing inter-cell fluxes. This approach almost achieves computational speed typical of the coarse grids while preserving, to a significant extent, the accuracy offered by the much higher resolution available DEM. The simulations are carried out along each river of the network by forcing the hydraulic model with the streamflow hydrographs generated by HRR. Hydrographs are scaled so that the peak

  16. Quantification of nitrous oxide (N2O) emissions and soluble microbial product (SMP) production by a modified AOB-NOB-N2O-SMP model.

    Science.gov (United States)

    Kim, MinJeong; Wu, Guangxue; Yoo, ChangKyoo

    2017-03-01

    A modified AOB-NOB-N 2 O-SMP model able to quantify nitrous oxide (N 2 O) emissions and soluble microbial product (SMP) production during wastewater treatment is proposed. The modified AOB-NOB-N 2 O-SMP model takes into account: (1) two-step nitrification by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), (2) N 2 O production by AOB denitrification under oxygen-limited conditions and (3) SMP production by microbial growth and endogenous respiration. Validity of the modified model is demonstrated by comparing the simulation results with experimental data from lab-scale sequencing batch reactors (SBRs). To reliably implement the modified model, a model calibration that adjusts model parameters to fit the model outputs to the experimental data is conducted. The results of this study showed that the modeling accuracy of the modified AOB-NOB-N 2 O-SMP model increases by 19.7% (NH 4 ), 51.0% (NO 2 ), 57.8% (N 2 O) and 16.7% (SMP) compared to the conventional model which does not consider the two-step nitrification and SMP production by microbial endogenous respiration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. A statistical simulation model for field testing of non-target organisms in environmental risk assessment of genetically modified plants.

    Science.gov (United States)

    Goedhart, Paul W; van der Voet, Hilko; Baldacchino, Ferdinando; Arpaia, Salvatore

    2014-04-01

    Genetic modification of plants may result in unintended effects causing potentially adverse effects on the environment. A comparative safety assessment is therefore required by authorities, such as the European Food Safety Authority, in which the genetically modified plant is compared with its conventional counterpart. Part of the environmental risk assessment is a comparative field experiment in which the effect on non-target organisms is compared. Statistical analysis of such trials come in two flavors: difference testing and equivalence testing. It is important to know the statistical properties of these, for example, the power to detect environmental change of a given magnitude, before the start of an experiment. Such prospective power analysis can best be studied by means of a statistical simulation model. This paper describes a general framework for simulating data typically encountered in environmental risk assessment of genetically modified plants. The simulation model, available as Supplementary Material, can be used to generate count data having different statistical distributions possibly with excess-zeros. In addition the model employs completely randomized or randomized block experiments, can be used to simulate single or multiple trials across environments, enables genotype by environment interaction by adding random variety effects, and finally includes repeated measures in time following a constant, linear or quadratic pattern in time possibly with some form of autocorrelation. The model also allows to add a set of reference varieties to the GM plants and its comparator to assess the natural variation which can then be used to set limits of concern for equivalence testing. The different count distributions are described in some detail and some examples of how to use the simulation model to study various aspects, including a prospective power analysis, are provided.

  18. A modified RRSQRT-filter for assimilating data in atmospheric chemistry models

    NARCIS (Netherlands)

    Segers, A.J.; Heemink, A.W.; Verlaan, M.; Loon, M. van

    2000-01-01

    The RRSQRT-filter is a special formulation of the Kalman filter for assimilation of data in large scale models. In this formulation, the covariance matrix of the model state is expressed in a limited number of modes. Two modifications have been made to the filter such that it is more robust when

  19. Implementation of the Modified Hoek-Brown Model into the Finite Element Method

    DEFF Research Database (Denmark)

    Sørensen, Emil Smed; Clausen, Johan Christian; Merifield, Richard S.

    2015-01-01

    The Hoek-Brown model for near-homogeneous rock masses will, in some cases, overpredict the tensile strength of the material. In some cases this can lead to unsafe design of structures. Therefore, a tension cut-off is introduced and the model is implemented into an elasto-plastic framework for use...

  20. Neutron star properties from an NJL model modified to simulate confinement

    Energy Technology Data Exchange (ETDEWEB)

    Lawley, S. [Special Research Centre for the Subatomic Structure of Matter, University of Adelaide, Adelaide SA 5005 (Australia); Bentz, W. [Department of Physics, School of Science, Tokai University, 117 Kita-Kaname, Hiratsuka 259-1207 (Japan); Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

    2005-04-15

    The NJL model has recently been extended with a method to simulate confinement. This leads in mean field approximation to a natural mechanism for the saturation of nuclear matter. We use the model to investigate the equation of state of asymmetric nuclear matter and then use it to compute the properties of neutron stars.

  1. Correspondence of f(R,∇R) Modified Gravity with Scalar Field Models

    International Nuclear Information System (INIS)

    Jawad, Abdul; Debnath, Ujjal

    2014-01-01

    This paper is devoted to study the scalar field dark energy models by taking its different aspects in the framework of f(R,∇R) gravity. We consider flat FRW universe to construct the equation of state parameter governed by f(R,∇R) gravity. The stability of the model is discussed with the help of squared speed of sound parameter. It is found that models show quintessence behavior of the universe in stable as well as unstable modes. We also develop the correspondence of f(R,∇R) model with some scalar field dark energy models like quintessence, tachyonic field, k-essence, dilaton, hessence, and DBI-essence. The nature of scalar fields and corresponding scalar potentials is being analyzed in f(R,∇R) gravity graphically which show consistency with the present day observations about accelerated phenomenon

  2. A Modified Critical State Two-surface Plasticity Model for Sand

    DEFF Research Database (Denmark)

    Bakmar, Christian LeBlanc; Hededal, O.; Ibsen, Lars Bo

    This paper provides background information and documentation for the implementation of a robust plasticity model as a user-subroutine in the commercial finite difference code, FLAC3D by Itasca. The plasticity model presented is equal to the 3 dimensional critical state two-surface plasticity model...... volumetric and stress-strain behaviour under monotonic and cyclic loading and thereby related observations like accumulation of pore pressure, cyclic mobility and cyclic liquefaction. The plasticity model is implemented with an integration scheme based on the general return mapping algorithm. The integration...... scheme faces convergence difficulties, primarily at very low mean effective stresses. The convergence problems are addressed by suitable correction strategies designed to add robustness, stability and efficiency to the integration scheme. An outline of all model parameters is given with suggestions...

  3. A Modified Active Appearance Model Based on an Adaptive Artificial Bee Colony

    Science.gov (United States)

    Othman, Zulaiha Ali

    2014-01-01

    Active appearance model (AAM) is one of the most popular model-based approaches that have been extensively used to extract features by highly accurate modeling of human faces under various physical and environmental circumstances. However, in such active appearance model, fitting the model with original image is a challenging task. State of the art shows that optimization method is applicable to resolve this problem. However, another common problem is applying optimization. Hence, in this paper we propose an AAM based face recognition technique, which is capable of resolving the fitting problem of AAM by introducing a new adaptive ABC algorithm. The adaptation increases the efficiency of fitting as against the conventional ABC algorithm. We have used three datasets: CASIA dataset, property 2.5D face dataset, and UBIRIS v1 images dataset in our experiments. The results have revealed that the proposed face recognition technique has performed effectively, in terms of accuracy of face recognition. PMID:25165748

  4. Connexin 43 Gene Therapy Delivered by Polymer-Modified Salmonella in Murine Tumor Models

    Directory of Open Access Journals (Sweden)

    Wei-Kuang Wang

    2014-04-01

    Full Text Available The use of preferentially tumor-targeting bacteria as vectors is one of the most innovative approaches for the treatment of cancer. This method is based on the observation that some obligate or facultative anaerobic bacteria are capable of selectively multiplying in tumors and inhibiting their growth. Previously, we found that the tumor-targeting efficiency of Salmonella could be modulated by modifying the immune response to these bacteria by coating them with poly(allylamine hydrochloride (PAH, and these organisms are designated PAH-S.C. (S. choleraesuis. PAH can provide a useful platform for the chemical modification of Salmonella, perhaps by allowing a therapeutic gene to bind to tumor-targeting Salmonella. This study aimed to investigate the benefits of the use of PAH-S.C. for gene delivery. To evaluate this modulation, the invasion activity and gene transfer of DNA-PAH-S.C. were measured in vitro and in vivo. Treatment with PAH-S.C. carrying a tumor suppressor gene (connexin 43 resulted in inhibition of tumor growth, which suggested that tumor-targeted gene therapy using PAH-S.C. carrying a therapeutic gene could exert antitumor activities. This technique represents a promising strategy for the treatment of tumors.

  5. A modified three-term PRP conjugate gradient algorithm for optimization models.

    Science.gov (United States)

    Wu, Yanlin

    2017-01-01

    The nonlinear conjugate gradient (CG) algorithm is a very effective method for optimization, especially for large-scale problems, because of its low memory requirement and simplicity. Zhang et al. (IMA J. Numer. Anal. 26:629-649, 2006) firstly propose a three-term CG algorithm based on the well known Polak-Ribière-Polyak (PRP) formula for unconstrained optimization, where their method has the sufficient descent property without any line search technique. They proved the global convergence of the Armijo line search but this fails for the Wolfe line search technique. Inspired by their method, we will make a further study and give a modified three-term PRP CG algorithm. The presented method possesses the following features: (1) The sufficient descent property also holds without any line search technique; (2) the trust region property of the search direction is automatically satisfied; (3) the steplengh is bounded from below; (4) the global convergence will be established under the Wolfe line search. Numerical results show that the new algorithm is more effective than that of the normal method.

  6. Cosmological model from the holographic equipartition law with a modified Renyi entropy

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Nobuyoshi [Kanazawa University, Department of Mechanical Systems Engineering, Kanazawa, Ishikawa (Japan)

    2017-04-15

    Cosmological equations were recently derived by Padmanabhan from the expansion of cosmic space due to the difference between the degrees of freedom on the surface and in the bulk in a region of space. In this study, a modified Renyi entropy is applied to Padmanabhan's 'holographic equipartition law', by regarding the Bekenstein-Hawking entropy as a nonextensive Tsallis entropy and using a logarithmic formula of the original Renyi entropy. Consequently, the acceleration equation including an extra driving term (such as a time-varying cosmological term) can be derived in a homogeneous, isotropic, and spatially flat universe. When a specific condition is mathematically satisfied, the extra driving term is found to be constant-like as if it is a cosmological constant. Interestingly, the order of the constant-like term is naturally consistent with the order of the cosmological constant measured by observations, because the specific condition constrains the value of the constant-like term. (orig.)

  7. Modified Ashworth Scale (MAS) Model based on Clinical Data Measurement towards Quantitative Evaluation of Upper Limb Spasticity

    Science.gov (United States)

    Puzi, A. Ahmad; Sidek, S. N.; Mat Rosly, H.; Daud, N.; Yusof, H. Md

    2017-11-01

    Spasticity is common symptom presented amongst people with sensorimotor disabilities. Imbalanced signals from the central nervous systems (CNS) which are composed of the brain and spinal cord to the muscles ultimately leading to the injury and death of motor neurons. In clinical practice, the therapist assesses muscle spasticity using a standard assessment tool like Modified Ashworth Scale (MAS), Modified Tardiue Scale (MTS) or Fugl-Meyer Assessment (FMA). This is done subjectively based on the experience and perception of the therapist subjected to the patient fatigue level and body posture. However, the inconsistency in the assessment is prevalent and could affect the efficacy of the rehabilitation process. Thus, the aim of this paper is to describe the methodology of data collection and the quantitative model of MAS developed to satisfy its description. Two subjects with MAS of 2 and 3 spasticity levels were involved in the clinical data measurement. Their level of spasticity was verified by expert therapist using current practice. Data collection was established using mechanical system equipped with data acquisition system and LABVIEW software. The procedure engaged repeated series of flexion of the affected arm that was moved against the platform using a lever mechanism and performed by the therapist. The data was then analyzed to investigate the characteristics of spasticity signal in correspondence to the MAS description. Experimental results revealed that the methodology used to quantify spasticity satisfied the MAS tool requirement according to the description. Therefore, the result is crucial and useful towards the development of formal spasticity quantification model.

  8. Variance components models for physical activity with age as modifier: a comparative twin study in seven countries

    DEFF Research Database (Denmark)

    Vink, Jacqueline M; Boomsma, Dorret I; Medland, Sarah E

    2011-01-01

    -reported data from twins aged 19 to 50 from seven countries that collaborated in the GenomEUtwin project: Australia, Denmark, Finland, Norway, Netherlands, Sweden and United Kingdom. Results confirmed the importance of genetic influences on physical activity in all countries and showed an age-related decrease......Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self...... into account when exploring the genetic and environmental contribution to physical activity. It also suggests that the power of genome-wide association studies to identify the genetic variants contributing to physical activity may be larger in young adult cohorts....

  9. A Modified Decomposed Theory of Planned Behaviour Model to Analyze User Intention towards Distance-Based Electronic Toll Collection Services

    Directory of Open Access Journals (Sweden)

    Chi-Chung Tao

    2017-02-01

    Full Text Available This study proposes a modified decomposed theory of planned behaviour model (DTPB that integrates satisfaction and trust into the original DTPB model to explore what kind of factors affect the user intention towards distance-based electronic toll collection (ETC services. The proposed model is empirically tested by using data collected from a questionnaire survey with a computer assisted telephone interview system. Empirical analysis is carried out in three stages that combine confirmatory factor analysis, structural equation modelling (SEM, and Bayesian network: (1 examination of reliability and validity of the measurement model; (2 analysis of structural model; (3 prediction of the probability of user intention change based on rigorous framework of SEM. The results confirm that the satisfaction and trust have positive effects on the behaviour intention, also validating that five constructs have indirect effects on the behaviour intention through attitude and perceived behaviour control. Compatibility is the most important influence factor, followed by perceived usefulness, facilitating conditions, self-efficacy, and perceived ease of use. The findings of this study identify potential improvements for ETC operator, such as contributing to the society to enhance the company image and trust of enterprise with charity activities, and simultaneously upgrading the information platform of website, software, and Apps.

  10. A modified variable physical properties model, for analyzing nanofluids flow and heat transfer over nonlinearly stretching sheet

    Directory of Open Access Journals (Sweden)

    Pooria Akbarzadeh

    2017-07-01

    Full Text Available In this paper, the problem of laminar nanofluid flow which results from the nonlinear stretching of a flat sheet is investigated numerically. In this paper, a modified variable physical properties model for analyzing nanofluids flow and heat transfer is introduced. In this model, the effective viscosity, density, and thermal conductivity of the solid-liquid mixture (nanofluids which are commonly utilized in the homogenous single-phase model, are locally combined with the prevalent single-phase model. A numerical similarity solution is considered which depends on the local Prandtl number, local Brownian motion number, local Lewis number, and local thermophoresis number. The results are compared to the prevalent single-phase model. This comparison depicts that the prevalent single-phase model has a considerable deviation for predicting the behavior of nanofluids flow especially in dimensionless temperature and nanoparticle volume fraction. In addition the effect of the governing parameters such as Prandtl number, the Brownian motion number, the thermophoresis parameter, the Lewis number, and etc. on the velocity, temperature, and volume fraction distribution and the dimensionless heat and mass transfer rates are examined.

  11. Modified cyanobacteria

    Science.gov (United States)

    Vermaas, Willem F J.

    2014-06-17

    Disclosed is a modified photoautotrophic bacterium comprising genes of interest that are modified in terms of their expression and/or coding region sequence, wherein modification of the genes of interest increases production of a desired product in the bacterium relative to the amount of the desired product production in a photoautotrophic bacterium that is not modified with respect to the genes of interest.

  12. A Modified Approach in Modeling and Calculation of Contact Characteristics of Rough Surfaces

    Directory of Open Access Journals (Sweden)

    J.A. Abdo

    2005-12-01

    Full Text Available A mathematical formulation for the contact of rough surfaces is presented. The derivation of the contact model is facilitated through the definition of plastic asperities that are assumed to be embedded at a critical depth within the actual surface asperities. The surface asperities are assumed to deform elastically whereas the plastic asperities experience only plastic deformation. The deformation of plastic asperities is made to obey the law of conservation of volume. It is believed that the proposed model is advantageous since (a it provides a more accurate account of elasticplastic behavior of surfaces in contact and (b it is applicable to model formulations that involve asperity shoulder-to shoulder contact. Comparison of numerical results for estimating true contact area and contact force using the proposed model and the earlier methods suggest that the proposed approach provides a more realistic prediction of elastic-plastic contact behavior.

  13. Stability and Bifurcation Analysis of a Modified Epidemic Model for Computer Viruses

    Directory of Open Access Journals (Sweden)

    Chuandong Li

    2014-01-01

    Full Text Available We extend the three-dimensional SIR model to four-dimensional case and then analyze its dynamical behavior including stability and bifurcation. It is shown that the new model makes a significant improvement to the epidemic model for computer viruses, which is more reasonable than the most existing SIR models. Furthermore, we investigate the stability of the possible equilibrium point and the existence of the Hopf bifurcation with respect to the delay. By analyzing the associated characteristic equation, it is found that Hopf bifurcation occurs when the delay passes through a sequence of critical values. An analytical condition for determining the direction, stability, and other properties of bifurcating periodic solutions is obtained by using the normal form theory and center manifold argument. The obtained results may provide a theoretical foundation to understand the spread of computer viruses and then to minimize virus risks.

  14. New holographic dark energy model with constant bulk viscosity in modified f(R,T) gravity theory

    Science.gov (United States)

    Srivastava, Milan; Singh, C. P.

    2018-06-01

    The aim of this paper is to study new holographic dark energy (HDE) model in modified f(R,T) gravity theory within the framework of a flat Friedmann-Robertson-Walker model with bulk viscous matter content. It is thought that the negative pressure caused by the bulk viscosity can play the role of dark energy component, and drive the accelerating expansion of the universe. This is the motive of this paper to observe such phenomena with bulk viscosity. In the specific model f(R,T)=R+λ T, where R is the Ricci scalar, T the trace of the energy-momentum tensor and λ is a constant, we find the solution for non-viscous and viscous new HDE models. We analyze new HDE model with constant bulk viscosity, ζ =ζ 0= const. to explain the present accelerated expansion of the universe. We classify all possible scenarios (deceleration, acceleration and their transition) with possible positive and negative ranges of λ over the constraint on ζ 0 to analyze the evolution of the universe. We obtain the solutions of scale factor and deceleration parameter, and discuss the evolution of the universe. We observe the future finite-time singularities of type I and III at a finite time under certain constraints on λ . We also investigate the statefinder and Om diagnostics of the viscous new HDE model to discriminate with other existing dark energy models. In late time the viscous new HDE model approaches to Λ CDM model. We also discuss the thermodynamics and entropy of the model and find that it satisfies the second law of thermodynamics.

  15. On market timing and portfolio selectivity: modifying the Henriksson-Merton model

    OpenAIRE

    Goś, Krzysztof

    2011-01-01

    This paper evaluates selected functionalities of the parametrical Henriksson-Merton test, a tool designed for measuring the market timing and portfolio selectivity capabilities. It also provides a solution to two significant disadvantages of the model: relatively indirect interpretation and vulnerability to parameter insignificance. The model has been put to test on a group of Polish mutual funds in a period of 63 months (January 2004 – March 2009), providing unsatisfa...

  16. Seismic response analysis of reactor containment structures - axisymmetric model with modified ground motion

    International Nuclear Information System (INIS)

    Saha, S.; Dasgupta, A.; Basu, P.C.

    1993-01-01

    Seismic analysis of a Reactor Building is performed idealising the system as a beam model (BM) and also an Axi-symmetric model (ASM) and the results compared. In both the cases effect of Soil-Structure Interaction have been taken Into account. Since the lower boundary of the ASM was at a depth much lower than that of the BM, deconvolution of the specified Free-Field Motion (FFM) was necessary. The deconvolution has been performed using frequency domain approach. (author)

  17. Modeling the modified drug release from curved shape drug delivery systems - Dome Matrix®.

    Science.gov (United States)

    Caccavo, D; Barba, A A; d'Amore, M; De Piano, R; Lamberti, G; Rossi, A; Colombo, P

    2017-12-01

    The controlled drug release from hydrogel-based drug delivery systems is a topic of large interest for research in pharmacology. The mathematical modeling of the behavior of these systems is a tool of emerging relevance, since the simulations can be of use in the design of novel systems, in particular for complex shaped tablets. In this work a model, previously developed, was applied to complex-shaped oral drug delivery systems based on hydrogels (Dome Matrix®). Furthermore, the model was successfully adopted in the description of drug release from partially accessible Dome Matrix® systems (systems with some surfaces coated). In these simulations, the erosion rate was used asa fitting parameter, and its dependence upon the surface area/volume ratio and upon the local fluid dynamics was discussed. The model parameters were determined by comparison with the drug release profile from a cylindrical tablet, then the model was successfully used for the prediction of the drug release from a Dome Matrix® system, for simple module configuration and for module assembled (void and piled) configurations. It was also demonstrated that, given the same initial S/V ratio, the drug release is independent upon the shape of the tablets but it is only influenced by the S/V evolution. The model reveals itself able to describe the observed phenomena, and thus it can be of use for the design of oral drug delivery systems, even if complex shaped. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Benchmarking of Generation and Distribution Units in Nepal Using Modified DEA Models

    Science.gov (United States)

    Jha, Deependra Kumar; Yorino, Naoto; Zoka, Yoshifumi

    This paper analyzes the performance of Nepalese Electricity Supply Industry (ESI) by investigating the relative operational efficiencies of the generating stations as well as the Distribution Centers (DCs) of the Integrated Nepal Power System (INPS). Nepal Electricity Authority (NEA), a state owned utility, owns and operates the INPS. Performance evaluation of both generation and distribution systems is carried out by formulating suitable weight restriction type Data Envelopment Analysis (DEA) models. The models include a wide range of inputs and outputs representing essence of the respective processes. Decision maker's preferences as well as available quantitative information associated with the operation of the Decision Making Units (DMUs) are judiciously incorporated in the DEA models. The proposed models are realized through execution of computer programs written in General Algebraic Modeling Systems (GAMS) and the results obtained are thus compared against those from the conventional DEA models. Sensitivity analysis is performed in order to check the robustness of the results as well as to identify the improvement directions for DMUs. Ranking of the DMUs has been presented based on their average overall efficiency scores.

  19. A modified exponential behavioral economic demand model to better describe consumption data.

    Science.gov (United States)

    Koffarnus, Mikhail N; Franck, Christopher T; Stein, Jeffrey S; Bickel, Warren K

    2015-12-01

    Behavioral economic demand analyses that quantify the relationship between the consumption of a commodity and its price have proven useful in studying the reinforcing efficacy of many commodities, including drugs of abuse. An exponential equation proposed by Hursh and Silberberg (2008) has proven useful in quantifying the dissociable components of demand intensity and demand elasticity, but is limited as an analysis technique by the inability to correctly analyze consumption values of zero. We examined an exponentiated version of this equation that retains all the beneficial features of the original Hursh and Silberberg equation, but can accommodate consumption values of zero and improves its fit to the data. In Experiment 1, we compared the modified equation with the unmodified equation under different treatments of zero values in cigarette consumption data collected online from 272 participants. We found that the unmodified equation produces different results depending on how zeros are treated, while the exponentiated version incorporates zeros into the analysis, accounts for more variance, and is better able to estimate actual unconstrained consumption as reported by participants. In Experiment 2, we simulated 1,000 datasets with demand parameters known a priori and compared the equation fits. Results indicated that the exponentiated equation was better able to replicate the true values from which the test data were simulated. We conclude that an exponentiated version of the Hursh and Silberberg equation provides better fits to the data, is able to fit all consumption values including zero, and more accurately produces true parameter values. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  20. Development and evaluation of bevacizumab-modified pegylated cationic liposomes using cellular and in vivo models of human pancreatic cancer

    Science.gov (United States)

    Kuesters, Geoffrey M.

    Targeting the tumor vascular supply in a homogenous manner is a difficult task to achieve with the use of pegylated cationic liposomes (PCLs) alone. Our formulation consisting of bevacizumab conjugated to the distal end of PEG on PCLs was thus developed in an effort to eliminate some of this heterogeneity as well as to increase tumor targeting overall. This study focuses on pancreatic cancer, which has the poorest five-year survival rate of all cancers because of its late diagnosis. The addition of bevacizumab will target tumor areas because it binds to VEGF which is secreted by tumors in high levels. In vitro, we showed that pancreatic cancer cells (Capan-1, HPAF-II and PANC-1) all secrete VEGF into media at different levels, with Capan-1 producing the most and HPAF-II producing the least. A murine endothelial cell line, MS1-VEGF, produces and secretes the most VEGF. A human microvascular endothelial cell line (HMEC-1) was grown in two different conditions, with and without VEGF in the media. Modifying PCLs with bevacizumab enhanced the binding and uptake of PCLs by some pancreatic and endothelial cells in vitro, particularly the cells that had or secreted the most significant amount of VEGF in the media. This translated into enhanced tumor targeting in a biodistribution study using a Capan-1 subcutaneous pancreatic tumor model. This also showed enhanced blood retention compared to the unmodified PCLs while it diminished uptake by the spleen and increased uptake by the kidney. To test the therapeutic benefit of this enhanced uptake and targeting, an anti-angiogenic agent, 2-methoxyestradiol was incorporated into the formulation with 20% incorporation efficiency. Both the unmodified and modified drug-loaded PCLs were the least efficacious against Capan-1, moderately effective against HPAF-II, PANC-1, MS1-VEGF and HMEC-1 grown without VEGF in the media and most efficacious against HMEC-1 grown with VEGF which had the most VEGF present in the media. Multiple in vivo

  1. Collective coordinate approximation to the scattering of solitons in modified NLS and sine-Gordon models

    International Nuclear Information System (INIS)

    Baron, H.E.; Zakrzewski, W.J.

    2016-01-01

    We investigate the validity of collective coordinate approximations to the scattering of two solitons in several classes of (1+1) dimensional field theory models. We consider models which are deformations of the sine-Gordon (SG) or the nonlinear Schrödinger (NLS) model which posses soliton solutions (which are topological (SG) or non-topological (NLS)). Our deformations preserve their topology (SG), but change their integrability properties, either completely or partially (models become ‘quasi-integrable’). As the collective coordinate approximation does not allow for the radiation of energy out of a system we look, in some detail, at how the approximation fares in models which are ‘quasi-integrable’ and therefore have asymptotically conserved charges (i.e. charges Q(t) for which Q(t→−∞)=Q(t→∞)). We find that our collective coordinate approximation, based on geodesic motion etc, works amazingly well in all cases where it is expected to work. This is true for the physical properties of the solitons and even for their quasi-conserved (or not) charges. The only time the approximation is not very reliable (and even then the qualitative features are reasonable, but some details are not reproduced well) involves the processes when the solitons come very close together (within one width of each other) during their scattering.

  2. Modified VMD model with correct analytic properties for describing electromagnetic structure of He4 nucleus

    International Nuclear Information System (INIS)

    Dubnicka, S.; Lucan, L.

    1988-12-01

    A new phenomenological model for electromagnetic (e.m.) form factor (ff) of He 4 nucleus is presented, which is based on a modification of the well proved in e.m. interactions of hadrons vector-meson-dominance (VMD) model by means of an incorporation of correct He 4 ff analytic properties, nonzero vector-meson widths and the right power asymptotic behaviour predicted by the quark model. It reproduces the existing experimental information on He 4 e.m. ff in the space-like region quite well. Furthermore, couplings of all well established isoscalar vector mesons with J pc = 1 -- to He 4 nucleus are evaluated as a result of the analysis and the time-like region behaviour of He 4 e.m. ff is predicted. As a consequence of the latter the total cross section of e + e - → He 4 He-bar 4 process is calculated for the first time. (author). 17 refs, 3 figs

  3. Modified economic order quantity (EOQ model for items with imperfect quality: Game-theoretical approaches

    Directory of Open Access Journals (Sweden)

    Milad Elyasi

    2014-04-01

    Full Text Available In the recent decade, studying the economic order quantity (EOQ models with imperfect quality has appealed to many researchers. Only few papers are published discussing EOQ models with imperfect items in a supply chain. In this paper, a two-echelon decentralized supply chain consisting of a manufacture and a supplier that both face just in time (JIT inventory problem is considered. It is sought to find the optimal number of the shipments and the quantity of each shipment in a way that minimizes the both manufacturer’s and the supplier’s cost functions. To the authors’ best knowledge, this is the first paper that deals with imperfect items in a decentralized supply chain. Thereby, three different game theoretical solution approaches consisting of two non-cooperative games and a cooperative game are proposed. Comparing the results of three different scenarios with those of the centralized model, the conclusions are drawn to obtain the best approach.

  4. The modified version of the centre-of-mass correction to the bag model

    International Nuclear Information System (INIS)

    Bartelski, J.; Tatur, S.

    1986-01-01

    We propose the improvement of the recently considered version of the centre-of-mass correction to the bag model. We identify a nucleon bag with physical nucleon confined in an external fictitious spherical well potential with an additional external fictitious pressure characterized by the parameter b. The introduction of such a pressure restores the conservation of the canonical energy-momentum tensor, which was lost in the former model. We propose several methods to determine the numerical value of b. We calculate the Roper resonance mass as well as static electroweak parameters of a nucleon with centre-of-mass corrections taken into account. 7 refs., 1 tab. (author)

  5. Actuator Disc Model Using a Modified Rhie-Chow/SIMPLE Pressure Correction Algorithm

    DEFF Research Database (Denmark)

    Rethore, Pierre-Elouan; Sørensen, Niels

    2008-01-01

    An actuator disc model for the flow solver EllipSys (2D&3D) is proposed. It is based on a correction of the Rhie-Chow algorithm for using discreet body forces in collocated variable finite volume CFD code. It is compared with three cases where an analytical solution is known.......An actuator disc model for the flow solver EllipSys (2D&3D) is proposed. It is based on a correction of the Rhie-Chow algorithm for using discreet body forces in collocated variable finite volume CFD code. It is compared with three cases where an analytical solution is known....

  6. Estimation of Enthalpy of Formation of Liquid Transition Metal Alloys: A Modified Prescription Based on Macroscopic Atom Model of Cohesion

    Science.gov (United States)

    Raju, Subramanian; Saibaba, Saroja

    2016-09-01

    The enthalpy of formation Δo H f is an important thermodynamic quantity, which sheds significant light on fundamental cohesive and structural characteristics of an alloy. However, being a difficult one to determine accurately through experiments, simple estimation procedures are often desirable. In the present study, a modified prescription for estimating Δo H f L of liquid transition metal alloys is outlined, based on the Macroscopic Atom Model of cohesion. This prescription relies on self-consistent estimation of liquid-specific model parameters, namely electronegativity ( ϕ L) and bonding electron density ( n b L ). Such unique identification is made through the use of well-established relationships connecting surface tension, compressibility, and molar volume of a metallic liquid with bonding charge density. The electronegativity is obtained through a consistent linear scaling procedure. The preliminary set of values for ϕ L and n b L , together with other auxiliary model parameters, is subsequently optimized to obtain a good numerical agreement between calculated and experimental values of Δo H f L for sixty liquid transition metal alloys. It is found that, with few exceptions, the use of liquid-specific model parameters in Macroscopic Atom Model yields a physically consistent methodology for reliable estimation of mixing enthalpies of liquid alloys.

  7. FOG Random Drift Signal Denoising Based on the Improved AR Model and Modified Sage-Husa Adaptive Kalman Filter.

    Science.gov (United States)

    Sun, Jin; Xu, Xiaosu; Liu, Yiting; Zhang, Tao; Li, Yao

    2016-07-12

    In order to reduce the influence of fiber optic gyroscope (FOG) random drift error on inertial navigation systems, an improved auto regressive (AR) model is put forward in this paper. First, based on real-time observations at each restart of the gyroscope, the model of FOG random drift can be established online. In the improved AR model, the FOG measured signal is employed instead of the zero mean signals. Then, the modified Sage-Husa adaptive Kalman filter (SHAKF) is introduced, which can directly carry out real-time filtering on the FOG signals. Finally, static and dynamic experiments are done to verify the effectiveness. The filtering results are analyzed with Allan variance. The analysis results show that the improved AR model has high fitting accuracy and strong adaptability, and the minimum fitting accuracy of single noise is 93.2%. Based on the improved AR(3) model, the denoising method of SHAKF is more effective than traditional methods, and its effect is better than 30%. The random drift error of FOG is reduced effectively, and the precision of the FOG is improved.

  8. Hysteresis compensation of the Prandtl-Ishlinskii model for piezoelectric actuators using modified particle swarm optimization with chaotic map.

    Science.gov (United States)

    Long, Zhili; Wang, Rui; Fang, Jiwen; Dai, Xufei; Li, Zuohua

    2017-07-01

    Piezoelectric actuators invariably exhibit hysteresis nonlinearities that tend to become significant under the open-loop condition and could cause oscillations and errors in nanometer-positioning tasks. Chaotic map modified particle swarm optimization (MPSO) is proposed and implemented to identify the Prandtl-Ishlinskii model for piezoelectric actuators. Hysteresis compensation is attained through application of an inverse Prandtl-Ishlinskii model, in which the parameters are formulated based on the original model with chaotic map MPSO. To strengthen the diversity and improve the searching ergodicity of the swarm, an initial method of adaptive inertia weight based on a chaotic map is proposed. To compare and prove that the swarm's convergence occurs before stochastic initialization and to attain an optimal particle swarm optimization algorithm, the parameters of a proportional-integral-derivative controller are searched using self-tuning, and the simulated results are used to verify the search effectiveness of chaotic map MPSO. The results show that chaotic map MPSO is superior to its competitors for identifying the Prandtl-Ishlinskii model and that the inverse Prandtl-Ishlinskii model can provide hysteresis compensation under different conditions in a simple and effective manner.

  9. Evaluation and determination of soil remediation schemes using a modified AHP model and its application in a contaminated coking plant.

    Science.gov (United States)

    Li, Xingang; Li, Jia; Sui, Hong; He, Lin; Cao, Xingtao; Li, Yonghong

    2018-07-05

    Soil remediation has been considered as one of the most difficult pollution treatment tasks due to its high complexity in contaminants, geological conditions, usage, urgency, etc. The diversity in remediation technologies further makes quick selection of suitable remediation schemes much tougher even the site investigation has been done. Herein, a sustainable decision support hierarchical model has been developed to select, evaluate and determine preferred soil remediation schemes comprehensively based on modified analytic hierarchy process (MAHP). This MAHP method combines competence model and the Grubbs criteria with the conventional AHP. It not only considers the competence differences among experts in group decision, but also adjusts the big deviation caused by different experts' preference through sample analysis. This conversion allows the final remediation decision more reasonable. In this model, different evaluation criteria, including economic effect, environmental effect and technological effect, are employed to evaluate the integrated performance of remediation schemes followed by a strict computation using above MAHP. To confirm the feasibility of this developed model, it has been tested by a benzene workshop contaminated site in Beijing coking plant. Beyond soil remediation, this MAHP model would also be applied in other fields referring to multi-criteria group decision making. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Disease-modifying effect of atipamezole in a model of post-traumatic epilepsy.

    Science.gov (United States)

    Nissinen, Jari; Andrade, Pedro; Natunen, Teemu; Hiltunen, Mikko; Malm, Tarja; Kanninen, Katja; Soares, Joana I; Shatillo, Olena; Sallinen, Jukka; Ndode-Ekane, Xavier Ekolle; Pitkänen, Asla

    2017-10-01

    Treatment of TBI remains a major unmet medical need, with 2.5 million new cases of traumatic brain injury (TBI) each year in Europe and 1.5 million in the USA. This single-center proof-of-concept preclinical study tested the hypothesis that pharmacologic neurostimulation with proconvulsants, either atipamezole, a selective α 2 -adrenoceptor antagonist, or the cannabinoid receptor 1 antagonist SR141716A, as monotherapy would improve functional recovery after TBI. A total of 404 adult Sprague-Dawley male rats were randomized into two groups: sham-injured or lateral fluid-percussion-induced TBI. The rats were treated with atipamezole (started at 30min or 7 d after TBI) or SR141716A (2min or 30min post-TBI) for up to 9 wk. Total follow-up time was 14 wk after treatment initiation. Outcome measures included motor (composite neuroscore, beam-walking) and cognitive performance (Morris water-maze), seizure susceptibility, spontaneous seizures, and cortical and hippocampal pathology. All injured rats exhibited similar impairment in the neuroscore and beam-walking tests at 2 d post-TBI. Atipamezole treatment initiated at either 30min or 7 d post-TBI and continued for 9 wk via subcutaneous osmotic minipumps improved performance in both the neuroscore and beam-walking tests, but not in the Morris water-maze spatial learning and memory test. Atipamezole treatment initiated at 7 d post-TBI also reduced seizure susceptibility in the pentylenetetrazol test 14 wk after treatment initiation, although it did not prevent the development of epilepsy. SR141716A administered as a single dose at 2min post-TBI or initiated at 30min post-TBI and continued for 9 wk had no recovery-enhancing or antiepileptogenic effects. Mechanistic studies to assess the α 2 -adrenoceptor subtype specificity of the disease-modifying effects of atipametzole revealed that genetic ablation of α 2A -noradrenergic receptor function in Adra2A mice carrying an N79P point mutation had antiepileptogenic effects

  11. Modified calibration protocol evaluated in a model-based testing of SBR flexibility

    DEFF Research Database (Denmark)

    Corominas, Lluís; Sin, Gürkan; Puig, Sebastià

    2011-01-01

    The purpose of this paper is to refine the BIOMATH calibration protocol for SBR systems, in particular to develop a pragmatic calibration protocol that takes advantage of SBR information-rich data, defines a simulation strategy to obtain proper initial conditions for model calibration and provide...

  12. AN APPLICATION OF CHOICE MODELING TO MEASURE U.S. CONSUMER PREFERENCES FOR GENETICALLY MODIFIED FOODS

    OpenAIRE

    Onyango, Benjamin M.; Govindasamy, Ramu; Nayga, Rodolfo M., Jr.

    2004-01-01

    Food biotechnology promises to deliver a wide range of enhanced consumer benefits. This study models consumer's willingness to trade-off the potential risks of GM foods with the possibility of extracting significant benefits. It estimates the marginal effects and relationships between product characteristics and consumer attributes on acceptance of GM foods.

  13. A Modified Model for Deflection Calculation of Reinforced Concrete Beam with Deformed GFRP Rebar

    Directory of Open Access Journals (Sweden)

    Minkwan Ju

    2016-01-01

    Full Text Available The authors carried out experimental and analytical research to evaluate the flexural capacity and the moment-deflection relationship of concrete beams reinforced with GFRP bars. The proposed model to predict the effective moment of inertia for R/C beam with GFRP bars was developed empirically, based on Branson’s equation to have better accuracy and a familiar approach to a structural engineer. For better prediction of the moment-deflection relationship until the ultimate strength is reached, a nonlinear parameter (k was also considered. This parameter was introduced to reduce the effect of the cracked moment of inertia for the reinforced concrete member, including a lower reinforcement ratio and modulus of elasticity of the GFRP bar. In a comparative study using six equations suggested by others, the proposed model showed better agreement with the experimental test results. It was confirmed that the empirical modification based on Branson’s equation was valid for predicting the effective moment of inertia of R/C beams with GFRP bar in this study. To evaluate the generality of the proposed model, a comparative study using previous test results from the literature and the results from this study was carried out. It was found that the proposed model had better accuracy and was a familiar approach to structural engineers to predict and evaluate the deflection behavior.

  14. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...

  15. Experimental investigation and modeling of industrial oily wastewater treatment using modified polyethersulfone ultrafiltration hollow fiber membranes

    International Nuclear Information System (INIS)

    Salahi, Abdolhamid; Mohammadi, Toraj; Behbahani, Reza Mosayebi; Hemmati, Mahmood

    2015-01-01

    Hollow fiber membranes were prepared from polyethersulfone/additives/NMP and DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L 16 orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m 2 h). Moreover, Hermia's models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model

  16. Modified creep and shrinkage prediction model B3 for serviceability limit state analysis of composite slabs

    Science.gov (United States)

    Gholamhoseini, Alireza

    2016-03-01

    Relatively little research has been reported on the time-dependent in-service behavior of composite concrete slabs with profiled steel decking as permanent formwork and little guidance is available for calculating long-term deflections. The drying shrinkage profile through the thickness of a composite slab is greatly affected by the impermeable steel deck at the slab soffit, and this has only recently been quantified. This paper presents the results of long-term laboratory tests on composite slabs subjected to both drying shrinkage and sustained loads. Based on laboratory measurements, a design model for the shrinkage strain profile through the thickness of a slab is proposed. The design model is based on some modifications to an existing creep and shrinkage prediction model B3. In addition, an analytical model is developed to calculate the time-dependent deflection of composite slabs taking into account the time-dependent effects of creep and shrinkage. The calculated deflections are shown to be in good agreement with the experimental measurements.

  17. Experimental investigation and modeling of industrial oily wastewater treatment using modified polyethersulfone ultrafiltration hollow fiber membranes

    Energy Technology Data Exchange (ETDEWEB)

    Salahi, Abdolhamid; Mohammadi, Toraj [Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Behbahani, Reza Mosayebi [Petroleum University of Technology (PUT), Ahwaz (Iran, Islamic Republic of); Hemmati, Mahmood [Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of)

    2015-06-15

    Hollow fiber membranes were prepared from polyethersulfone/additives/NMP and DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L{sub 16} orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m{sup 2}h). Moreover, Hermia's models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model.

  18. Evaluating Forest Vegetation Simulator predictions for southern Appalachian upland hardwoods with a modified mortality model

    Science.gov (United States)

    Philip J. Radtke; Nathan D. Herring; David L. Loftis; Chad E. Keyser

    2012-01-01

    Prediction accuracy for projected basal area and trees per acre was assessed for the growth and yield model of the Forest Vegetation Simulator Southern Variant (FVS-Sn). Data for comparison with FVS-Sn predictions were compiled from a collection of n

  19. Three-Dimensional Model Test Study of Modified Caisson Breakwater at Port of Castellon, Spain

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke

    caisson breakwater at Port of Castellon, Spain, tested earlier (Nørgaard & Lykke Andersen, 2013). Associate Prof. Thomas Lykke Andersen and M.Sc. Jørgen Quvang Harck Nørgaard were in charge of the model tests. Engineer assistant Niels Drustrup assisted in the laboratory with the construction...

  20. Modified Thermodynamic Equilibrium Model for Biomass Gasification: A Study of the Influence of Operating Conditions

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Bruno, Juan Carlos; Coronas, Alberto

    2012-01-01

    data from different authors for downdraft, fluidized-bed gasifiers and different biomasses, showing good agreement between reported data and modeled values. In addition, it has been used to evaluate the influence of different operating parameters [equivalence ratio (ER), air preheating, steam injection...

  1. Constitutive relationships of hot stamping boron steel B1500HS based on the modified Arrhenius and Johnson–Cook model

    International Nuclear Information System (INIS)

    Li, Huiping; He, Lianfang; Zhao, Guoqun; Zhang, Lei

    2013-01-01

    Constitutive relationship of boron steel is one of the most necessary mathematical models in the numerical simulation of hot stamping; it describes the relationship of the flow stress with strain, strain rate and temperature. In order to attain the constitutive relationship of boron steel B1500HS, four types of samples with microstructure of austenite, ferrite+pearlite, bainite or martensite are prepared by the Gleeble 1500D thermo-mechanical simulator. Isothermal uniaxial tension testings for these specimens are performed at 20–900 °C at the strain rates of 0.01 s –1 , 0.1 s –1 , 1.0 s –1 and 10 s –1 by Gleeble 1500D, and the true stress–strain curves at the relative conditions are gained. The experimental results show that, the flow stress of samples with relative microstructure rises with the decrease of the deformation temperature, and with the increase of the strain rate. The modified Arrhenius model is used to describe the hot deformation of samples with austenite microstructure, and the modified Johnson–Cook model is used to describe the deformation process of samples with ferrite+pearlite, bainite or martensite microstructure. The constitutive equations depending on the strain, strain rate and temperature are attained by the regression analysis for the experimental data of flow stress, strain, strain rate, temperature, etc. The comparison of the computational data and the experimental results shows that, the computational data using the constitutive relationships are well consistent with the experimental data

  2. NASA-Modified Precipitation Products to Improve EPA Nonpoint Source Water Quality Modeling for the Chesapeake Bay

    Science.gov (United States)

    Nigro, Joseph; Toll, David; Partington, Ed; Ni-Meister, Wenge; Lee, Shihyan; Gutierrez-Magness, Angelica; Engman, Ted; Arsenault, Kristi

    2010-01-01

    The Environmental Protection Agency (EPA) has estimated that over 20,000 water bodies within the United States do not meet water quality standards. Ninety percent of the impairments are typically caused by nonpoint sources. One of the regulations in the Clean Water Act of 1972 requires States to monitor the Total Maximum Daily Load (TMDL), or the amount of pollution that can be carried by a water body before it is determined to be "polluted", for any watershed in the U.S.. In response to this mandate, the EPA developed Better Assessment Science Integrating Nonpoint Sources (BASINS) as a Decision Support Tool (DST) for assessing pollution and to guide the decision making process for improving water quality. One of the models in BASINS, the Hydrological Simulation Program -- Fortran (HSPF), computes daily stream flow rates and pollutant concentration at each basin outlet. By design, precipitation and other meteorological data from weather stations serve as standard model input. In practice, these stations may be unable to capture the spatial heterogeneity of precipitation events especially if they are few and far between. An attempt was made to resolve this issue by substituting station data with NASA modified/NOAA precipitation data. Using these data within HSPF, stream flow was calculated for seven watersheds in the Chesapeake Bay Basin during low flow periods, convective storm periods, and annual flows. In almost every case, the modeling performance of HSPF increased when using the NASA-modified precipitation data, resulting in better stream flow statistics and, ultimately, in improved water quality assessment.

  3. A new peak detection algorithm for MALDI mass spectrometry data based on a modified Asymmetric Pseudo-Voigt model.

    Science.gov (United States)

    Wijetunge, Chalini D; Saeed, Isaam; Boughton, Berin A; Roessner, Ute; Halgamuge, Saman K

    2015-01-01

    Mass Spectrometry (MS) is a ubiquitous analytical tool in biological research and is used to measure the mass-to-charge ratio of bio-molecules. Peak detection is the essential first step in MS data analysis. Precise estimation of peak parameters such as peak summit location and peak area are critical to identify underlying bio-molecules and to estimate their abundances accurately. We propose a new method to detect and quantify peaks in mass spectra. It uses dual-tree complex wavelet transformation along with Stein's unbiased risk estimator for spectra smoothing. Then, a new method, based on the modified Asymmetric Pseudo-Voigt (mAPV) model and hierarchical particle swarm optimization, is used for peak parameter estimation. Using simulated data, we demonstrated the benefit of using the mAPV model over Gaussian, Lorentz and Bi-Gaussian functions for MS peak modelling. The proposed mAPV model achieved the best fitting accuracy for asymmetric peaks, with lower percentage errors in peak summit location estimation, which were 0.17% to 4.46% less than that of the other models. It also outperformed the other models in peak area estimation, delivering lower percentage errors, which were about 0.7% less than its closest competitor - the Bi-Gaussian model. In addition, using data generated from a MALDI-TOF computer model, we showed that the proposed overall algorithm outperformed the existing methods mainly in terms of sensitivity. It achieved a sensitivity of 85%, compared to 77% and 71% of the two benchmark algorithms, continuous wavelet transformation based method and Cromwell respectively. The proposed algorithm is particularly useful for peak detection and parameter estimation in MS data with overlapping peak distributions and asymmetric peaks. The algorithm is implemented using MATLAB and the source code is freely available at http://mapv.sourceforge.net.

  4. Modified energy-deposition model, for the computation of the stopping-power ratio for small cavity sizes

    International Nuclear Information System (INIS)

    Janssens, A.C.A.

    1981-01-01

    This paper presents a modification to the Spencer-Attix theory, which allows application of the theory to larger cavity sizes. The modified theory is in better agreement with the actual process of energy deposition by delta rays. In the first part of the paper it is recalled how the Spencer-Attix theory can be derived from basic principles, which allows a physical interpretation of the theory in terms of a function describing the space and direction average of the deposited energy. A realistic model for the computation of this function is described and the resulting expression for the stopping-power ratio is calculated. For the comparison between the Spencer-Attix theory and this modified expression a correction factor to the ''Bragg-Gray inhomogeneous term'' has been defined. This factor has been computed as a function of cavity size for different source energies and mean excitation energies; thus, general properties of this factor have been elucidated. The computations have been extended to include the density effect. It has been shown that the computation of the inhomogeneous term can be performed for any expression describing the energy loss per unit distance of the electrons as a function of their energy. Thus an expression has been calculated which is in agreement with a quadratic range-energy relationship. In conclusion, the concrete procedure for computing the stopping-power ratio is reviewed

  5. Dynamics of a modified Hindmarsh-Rose neural model with random perturbations: Moment analysis and firing activities

    Science.gov (United States)

    Mondal, Argha; Upadhyay, Ranjit Kumar

    2017-11-01

    In this paper, an attempt has been made to understand the activity of mean membrane voltage and subsidiary system variables with moment equations (i.e., mean, variance and covariance's) under noisy environment. We consider a biophysically plausible modified Hindmarsh-Rose (H-R) neural system injected by an applied current exhibiting spiking-bursting phenomenon. The effects of predominant parameters on the dynamical behavior of a modified H-R system are investigated. Numerically, it exhibits period-doubling, period halving bifurcation and chaos phenomena. Further, a nonlinear system has been analyzed for the first and second order moments with additive stochastic perturbations. It has been solved using fourth order Runge-Kutta method and noisy systems by Euler's scheme. It has been demonstrated that the firing properties of neurons to evoke an action potential in a certain parameter space of the large exact systems can be estimated using an approximated model. Strong stimulation can cause a change in increase or decrease of the firing patterns. Corresponding to a fixed set of parameter values, the firing behavior and dynamical differences of the collective variables of a large, exact and approximated systems are investigated.

  6. Effect of a shear modified Gurson model on damage development in a FSW tensile specimen

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Tvergaard, Viggo

    2009-01-01

    For a friction stir welded aluminum plate the resistance to ductile failure is studied by analyzing tensile test specimens cut out across the weldline. As the stress triaxiality is rather low in these tests, the Gurson material model is not expected to give a very accurate description of the void......, such that the damage parameter does not really represent the void volume fraction. Various amounts of the additional damage evolution are compared with predictions of the original Gurson model. The analyses are carried out for different yield stress profiles transverse to the weld and for different specimen widths....... It is found that the modification does provide additional damage development in the friction stir weld, which may help to fit experimental data. But the suggested modification depends strongly on the overall stress state, and may have a too strong effect in some cases where the stress triaxiality is rather...

  7. Towards Dense Nuclear Matter in A Modified Sakai-Sugimoto Model

    Directory of Open Access Journals (Sweden)

    Rho Mannque

    2012-02-01

    Full Text Available As a part of the attempt to address dense baryonic matter, we first review holographic approaches to QCD. The big advantage of the holographic approaches is that they render strongly coupled 4D gauge theories as duals of certain weakly coupled string/supergravity that are well understood. Its relevance to real QCD is one of the central problems in hadron/nuclear physics as well as in the context of applied string theory. None of the models based on these holographic approaches presently available can adequately describe the system we are interested in, namely dense baryonic matter. Nevertheless, some aspects of the holographic approach are found to describe certain processes both in vacuum and in medium. In this talk we only present the structure of a model that appears to be closest to QCD, and has the potential to address the problem.

  8. Ketogenic diet modifies the gut microbiota in a murine model of autism spectrum disorder.

    Science.gov (United States)

    Newell, Christopher; Bomhof, Marc R; Reimer, Raylene A; Hittel, Dustin S; Rho, Jong M; Shearer, Jane

    2016-01-01

    Gastrointestinal dysfunction and gut microbial composition disturbances have been widely reported in autism spectrum disorder (ASD). This study examines whether gut microbiome disturbances are present in the BTBR(T + tf/j) (BTBR) mouse model of ASD and if the ketogenic diet, a diet previously shown to elicit therapeutic benefit in this mouse model, is capable of altering the profile. Juvenile male C57BL/6 (B6) and BTBR mice were fed a standard chow (CH, 13 % kcal fat) or ketogenic diet (KD, 75 % kcal fat) for 10-14 days. Following diets, fecal and cecal samples were collected for analysis. Main findings are as follows: (1) gut microbiota compositions of cecal and fecal samples were altered in BTBR compared to control mice, indicating that this model may be of utility in understanding gut-brain interactions in ASD; (2) KD consumption caused an anti-microbial-like effect by significantly decreasing total host bacterial abundance in cecal and fecal matter; (3) specific to BTBR animals, the KD counteracted the common ASD phenotype of a low Firmicutes to Bacteroidetes ratio in both sample types; and (4) the KD reversed elevated Akkermansia muciniphila content in the cecal and fecal matter of BTBR animals. Results indicate that consumption of a KD likely triggers reductions in total gut microbial counts and compositional remodeling in the BTBR mouse. These findings may explain, in part, the ability of a KD to mitigate some of the neurological symptoms associated with ASD in an animal model.

  9. Grunting in genetically modified minipig animal model for Huntington ´s disease - a pilot experiment

    Czech Academy of Sciences Publication Activity Database

    Tykalová, T.; Hlavnička, J.; Mačáková, Monika; Baxa, Monika; Cmejla, R.; Motlík, Jan; Klempíř, J.; Rusz, J.

    2015-01-01

    Roč. 78, Suppl 2 (2015), s. 12-13 ISSN 1210-7859. [Conference on Animal Models for neurodegenerative Diseases /3./. 08.11.2015-10.11.2015, Liblice] R&D Projects: GA MŠk ED2.1.00/03.0124; GA MŠk(CZ) 7F14308 Institutional support: RVO:67985904 Keywords : Huntington ´s disease * mitochondria * DNA damage Subject RIV: FH - Neurology

  10. Modified positron annihilation model for glassy-like As2Se3

    International Nuclear Information System (INIS)

    Kozdras, A.; Shpotyuk, O.; Kovalskiy, A.; Filipecki, J.

    2005-01-01

    An approach to structural characterization of chalcogenide glasses based on the study of void distribution is discussed. The results of positron annihilation lifetime spectra measurements for glassy As 2 Se 3 are compared with nano-void distribution data obtained from Monte Carlo simulation. In this consideration perspectives to involve the parameters of nano-voids calculated from the first sharp diffraction peak in the frame work of known Elliott's model are analyzed. (author)

  11. Analytical studies on a modified Nagel-Schreckenberg model with the Fukui-Ishibashi acceleration rule

    International Nuclear Information System (INIS)

    Fu Chuanji; Wang Binghong; Yin Chuanyang; Zhou Tao; Hu Bo; Gao Kun; Hui, P.M.; Hu, C.-K.

    2007-01-01

    We propose and study a one-dimensional traffic flow cellular automaton model of high-speed vehicles with the Fukui-Ishibashi-type (FI) acceleration rule for all cars, and the Nagel-Schreckenberg-type (NS) stochastic delay mechanism. We obtain analytically the fundamental diagrams of the average speed and vehicle flux depending on the vehicle density and stochastic delay probability. Our theoretical results are in excellent agreement with numerical simulations

  12. A Modified Model for Deflection Calculation of Reinforced Concrete Beam with Deformed GFRP Rebar

    OpenAIRE

    Ju, Minkwan; Oh, Hongseob; Lim, Junhyun; Sim, Jongsung

    2016-01-01

    The authors carried out experimental and analytical research to evaluate the flexural capacity and the moment-deflection relationship of concrete beams reinforced with GFRP bars. The proposed model to predict the effective moment of inertia for R/C beam with GFRP bars was developed empirically, based on Branson’s equation to have better accuracy and a familiar approach to a structural engineer. For better prediction of the moment-deflection relationship until the ultimate strength is reached,...

  13. How Hot Precursor Modify Island Nucleation: A Rate-Equation Model

    Science.gov (United States)

    Morales-Cifuentes, Josue; Einstein, T. L.; Pimpinelli, Alberto

    2015-03-01

    We describe the analysis, based on rate equations, of the hot precursor model mentioned in the previous talk. Two key parameters are the competing times of ballistic monomers decaying into thermalized monomers vs. being captured by an island, which naturally define a ``thermalization'' scale for the system. We interpret the energies and dimmensionless parameters used in the model, and provide both an implicit analytic solution and a convenient asymptotic approximation. Further analysis reveals novel scaling regimes and nonmonotonic crossovers between them. To test our model, we applied it to experiments on parahexaphenyl (6P) on sputtered mica. With the resulting parameters, the curves derived from our analytic treatment account very well for the data at the 4 different temperatures. The fit shows that the high-flux regime corresponds not to ALA (attachment-limited aggregation) or HMA (hot monomer aggregation) but rather to an intermediate scaling regime related to DLA (diffusion-limited aggregation). We hope this work stimulates further experimental investigations. Work at UMD supported by NSF CHE 13-05892.

  14. Enhanced Deformation of Azobenzene-Modified Liquid Crystal Polymers under Dual Wavelength Exposure: A Photophysical Model

    Science.gov (United States)

    Liu, Ling; Onck, Patrick R.

    2017-08-01

    Azobenzene-embedded liquid crystal polymers can undergo mechanical deformation in response to ultraviolet (UV) light. The natural rodlike trans state azobenzene absorbs UV light and isomerizes to a bentlike cis state, which disturbs the order of the polymer network, leading to an anisotropic deformation. The current consensus is that the magnitude of the photoinduced deformation is related to the statistical building up of molecules in the cis state. However, a recent experimental study [Liu and Broer, Nat. Commun. 6 8334 (2015)., 10.1038/ncomms9334] shows that a drastic (fourfold) increase of the photoinduced deformation can be generated by exposing the samples simultaneously to 365 nm (UV) and 455 nm (visible) light. To elucidate the physical mechanism that drives this increase, we develop a two-light attenuation model and an optomechanical constitutive relation that not only accounts for the statistical accumulation of cis azobenzenes, but also for the dynamic trans-cis-trans oscillatory isomerization process. Our experimentally calibrated model predicts that the optimal single-wavelength exposure is 395 nm light, a pronounced shift towards the visible spectrum. In addition, we identify a range of optimal combinations of two-wavelength lights that generate a favorable response for a given amount of injected energy. Our model provides mechanistic insight into the different (multi)wavelength exposures used in experiments and, at the same time, opens new avenues towards enhanced, multiwavelength optomechanical behavior.

  15. Mechanistic model coupling gas exchange dynamics and Listeria monocytogenes growth in modified atmosphere packaging of non respiring food.

    Science.gov (United States)

    Chaix, E; Broyart, B; Couvert, O; Guillaume, C; Gontard, N; Guillard, V

    2015-10-01

    A mechanistic model coupling O2 and CO2 mass transfer (namely diffusion and solubilisation in the food itself and permeation through the packaging material) to microbial growth models was developed aiming at predicting the shelf life of modified atmosphere packaging (MAP) systems. It was experimentally validated on a non-respiring food by investigating concomitantly the O2/CO2 partial pressure in packaging headspace and the growth of Listeria monocytogenes (average microbial count) within the food sample. A sensitivity analysis has revealed that the reliability of the prediction by this "super-parametrized" model (no less than 47 parameters were required for running one simulation) was strongly dependent on the accuracy of the microbial input parameters. Once validated, this model was used to decipher the role of O2/CO2 mass transfer on microbial growth and as a MAP design tool: an example of MAP dimensioning was provided in this paper as a proof of concept. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. A modified Gurson-type plasticity model at finite strains: formulation, numerical analysis and phase-field coupling

    Science.gov (United States)

    Aldakheel, Fadi; Wriggers, Peter; Miehe, Christian

    2017-12-01

    The modeling of failure in ductile materials must account for complex phenomena at the micro-scale, such as nucleation, growth and coalescence of micro-voids, as well as the final rupture at the macro-scale, as rooted in the work of Gurson (J Eng Mater Technol 99:2-15, 1977). Within a top-down viewpoint, this can be achieved by the combination of a micro-structure-informed elastic-plastic model for a porous medium with a concept for the modeling of macroscopic crack discontinuities. The modeling of macroscopic cracks can be achieved in a convenient way by recently developed continuum phase field approaches to fracture, which are based on the regularization of sharp crack discontinuities, see Miehe et al. (Comput Methods Appl Mech Eng 294:486-522, 2015). This avoids the use of complex discretization methods for crack discontinuities, and can account for complex crack patterns. In this work, we develop a new theoretical and computational framework for the phase field modeling of ductile fracture in conventional elastic-plastic solids under finite strain deformation. It combines modified structures of Gurson-Tvergaard-Needelman GTN-type plasticity model outlined in Tvergaard and Needleman (Acta Metall 32:157-169, 1984) and Nahshon and Hutchinson (Eur J Mech A Solids 27:1-17, 2008) with a new evolution equation for the crack phase field. An important aspect of this work is the development of a robust Explicit-Implicit numerical integration scheme for the highly nonlinear rate equations of the enhanced GTN model, resulting with a low computational cost strategy. The performance of the formulation is underlined by means of some representative examples, including the development of the experimentally observed cup-cone failure mechanism.

  17. Design and modelling of enzyme/poly-pyrrole modified electrodes for bio-catalyzed electro-synthesis processes

    International Nuclear Information System (INIS)

    Gros, Pierre

    1996-01-01

    This research thesis reports a study which aims at developing, analyzing and integrating an electrode-enzyme interface within an electro-enzymatic reactor to develop electrochemical biosensors. The adopted method comprises a confinement of the enzyme at the electrode surface by means of an electro-formed poly-pyrrole film. The author reports an experimental and theoretical study of the coupling between electrochemical reaction, enzymatic reaction and matter transfer in the polymer in order to better understand the operation of so-modified electrodes. Different parameters have an influence on the reaction rate. A numerical model (validated by experiments) allows the identification of the reaction limiting stages. A new elaboration protocol allows the polymer permeability to be increased. The interface is first applied to the reduction of the NAD coenzyme, and the process is also applied to the production of gluconic acid [fr

  18. Approximate Analytical Solutions for Mathematical Model of Tumour Invasion and Metastasis Using Modified Adomian Decomposition and Homotopy Perturbation Methods

    Directory of Open Access Journals (Sweden)

    Norhasimah Mahiddin

    2014-01-01

    Full Text Available The modified decomposition method (MDM and homotopy perturbation method (HPM are applied to obtain the approximate solution of the nonlinear model of tumour invasion and metastasis. The study highlights the significant features of the employed methods and their ability to handle nonlinear partial differential equations. The methods do not need linearization and weak nonlinearity assumptions. Although the main difference between MDM and Adomian decomposition method (ADM is a slight variation in the definition of the initial condition, modification eliminates massive computation work. The approximate analytical solution obtained by MDM logically contains the solution obtained by HPM. It shows that HPM does not involve the Adomian polynomials when dealing with nonlinear problems.

  19. Reexamination of a novel determination of density, temperature, and symmetry energy based on a modified Fisher model

    Science.gov (United States)

    Liu, X.; Zheng, H.; Lin, W.; Huang, M.; Yang, Y. Y.; Wang, J. S.; Wada, R.; Bonasera, A.; Natowitz, J. B.

    2018-01-01

    In this article, a mistake in the formulation of the modified Fisher model (MFM) derived in the pioneering works of the Purdue group is addressed and corrected by reversing the sign of the mixing entropy term in the original formulation. The errors in the results of the previous MFM-related studies, such as isotopic yield distribution, isobaric yield ratios, isoscaling, m scaling, self-consistent determination of density, symmetry energy, and temperature, and density and temperature determination related to the intermediate mass fragment (IMF) freezeout, are quantitatively analyzed. It is found that the errors originating from the mistake in sign of the mixing entropy term are generally small and even have no effect in some cases.

  20. Thermogravimetric analysis and kinetic study of bamboo waste treated by Echinodontium taxodii using a modified three-parallel-reactions model.

    Science.gov (United States)

    Yu, Hongbo; Liu, Fang; Ke, Ming; Zhang, Xiaoyu

    2015-06-01

    In this study, the effect of pretreatment with Echinodontium taxodii on thermal decomposition characteristics and kinetics of bamboo wastes was investigated by thermogravimetric analysis. The results showed fungal pretreatment can enhance the thermal degradation of bamboo. The negative effect of extractives in bamboo on the thermal decomposition can be decreased by the pretreatment. A modified three-parallel-reactions model based on isolated lignin was firstly proposed to study pyrolysis kinetics of bamboo lignocellulose. Kinetic analysis showed that with increasing pretreatment time fungal delignification was enhanced to transform the lignin component with high activation energy into that with low activation energy and raise the cellulose content in bamboo, making the thermal decomposition easier. These results demonstrated fungal pretreatment provided a potential way to improve thermal conversion efficiency of bamboo. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Bending analysis of agglomerated carbon nanotube-reinforced beam resting on two parameters modified Vlasov model foundation

    Science.gov (United States)

    Ghorbanpour Arani, A.; Zamani, M. H.

    2018-06-01

    The present work deals with bending behavior of nanocomposite beam resting on two parameters modified Vlasov model foundation (MVMF), with consideration of agglomeration and distribution of carbon nanotubes (CNTs) in beam matrix. Equivalent fiber based on Eshelby-Mori-Tanaka approach is employed to determine influence of CNTs aggregation on elastic properties of CNT-reinforced beam. The governing equations are deduced using the principle of minimum potential energy under assumption of the Euler-Bernoulli beam theory. The MVMF required the estimation of γ parameter; to this purpose, unique iterative technique based on variational principles is utilized to compute value of the γ and subsequently fourth-order differential equation is solved analytically. Eventually, the transverse displacements and bending stresses are obtained and compared for different agglomeration parameters, various boundary conditions simultaneously and variant elastic foundation without requirement to instate values for foundation parameters.

  2. Application of the Modified Vlasov Model to the Free Vibration Analysis of Thick Plates Resting on Elastic Foundations

    Directory of Open Access Journals (Sweden)

    Korhan Ozgan

    2009-01-01

    Full Text Available The Modified Vlasov Model is applied to the free vibration analysis of thick plates resting on elastic foundations. The effects of the subsoil depth, plate dimensions and their ratio, the value of the vertical deformation parameter within the subsoil on the frequency parameters of plates on elastic foundations are investigated. A four-noded, twelve degrees of freedom quadrilateral finite element (PBQ4 is used for plate bending analysis based on Mindlin plate theory which is effectively applied to the analysis of thin and thick plates when selective reduced integration technique is used. The first ten natural frequency parameters are presented in tabular and graphical forms to show the effects of the parameters considered in the study. It is concluded that the effect of the subsoil depth on the frequency parameters of the plates on elastic foundation is generally larger than that of the other parameters considered in the study.

  3. Stringy models of modified gravity: space-time defects and structure formation

    International Nuclear Information System (INIS)

    Mavromatos, Nick E.; Sakellariadou, Mairi; Yusaf, Muhammad Furqaan

    2013-01-01

    Starting from microscopic models of space-time foam, based on brane universes propagating in bulk space-times populated by D0-brane defects (''D-particles''), we arrive at effective actions used by a low-energy observer on the brane world to describe his/her observations of the Universe. These actions include, apart from the metric tensor field, also scalar (dilaton) and vector fields, the latter describing the interactions of low-energy matter on the brane world with the recoiling point-like space-time defect (D-particle). The vector field is proportional to the recoil velocity of the D-particle and as such it satisfies a certain constraint. The vector breaks locally Lorentz invariance, which however is assumed to be conserved on average in a space-time foam situation, involving the interaction of matter with populations of D-particle defects. In this paper we clarify the role of fluctuations of the vector field on structure formation and galactic growth. In particular we demonstrate that, already at the end of the radiation era, the (constrained) vector field associated with the recoil of the defects provides the seeds for a growing mode in the evolution of the Universe. Such a growing mode survives during the matter dominated era, provided the variance of the D-particle recoil velocities on the brane is larger than a critical value. We note that in this model, as a result of specific properties of D-brane dynamics in the bulk, there is no issue of overclosing the brane Universe for large defect densities. Thus, in these models, the presence of defects may be associated with large-structure formation. Although our string inspired models do have (conventional, from a particle physics point of view) dark matter components, nevertheless it is interesting that the role of ''extra'' dark matter is also provided by the population of massive defects. This is consistent with the weakly interacting character of the D-particle defects, which predominantly interact only

  4. How "Hot Precursors" Modify Island Nucleation: A Rate-Equation Model

    Science.gov (United States)

    Morales-Cifuentes, Josue R.; Einstein, T. L.; Pimpinelli, A.

    2014-12-01

    We propose a novel island nucleation and growth model explicitly including transient (ballistic) mobility of the monomers deposited at rate F , assumed to be in a hot precursor state before thermalizing. In limiting regimes, corresponding to fast (diffusive) and slow (ballistic) thermalization, the island density N obeys scaling N ∝Fα . In between is found a rich, complex behavior, with various distinctive scaling regimes, characterized by effective exponents αeff and activation energies that we compute exactly. Application to N (F ,T ) of recent organic-molecule deposition experiments yields an excellent fit.

  5. The Effect of Video-Assisted Inquiry Modified Learning Model on Student’s Achievement on 1st Fundamental Physics Practice

    Directory of Open Access Journals (Sweden)

    T W Maduretno

    2017-12-01

    Full Text Available The purpose of research are: (1 to know the effect of video-assisted inquiry modified learning model on student’s achievement; (2 to improve the student’s achievement in 1st Fundamental Physics Practice through video-assisted inquiry modified learning model. The student’s achievement as dependent variables includes the aspects of knowledge, skill, and attitude. The sampling technique did not choose at random. The Mathematics Education as the control group and the Science Education as the experimental group. The experimental group used video-assisted inquiry modified learning model and the control group used inquiry learning model. The collecting data technique used observation, questionnaire, and test. The researcher used the independent t-test that purposed to compare the average of achievement of control and experiment group. The results of research were: (1 there was an effect of video-assisted inquiry modified learning model on the knowledge and skill aspect but there was not on the attitude aspect; (2 The average of learning outcome of the experimental group higher than the control group’s; (3 The video-assisted inquiry modified learning model helped more skilled and trained student to discovery, inquiry the scientific principle, experiment and observation, and explain the experiment and observation’s result so that the students be able to understand the materials on the 1st Fundamental Physics Practice.

  6. Modelling reduction of urban heat load in Vienna by modifying surface properties of roofs

    Science.gov (United States)

    Žuvela-Aloise, Maja; Andre, Konrad; Schwaiger, Hannes; Bird, David Neil; Gallaun, Heinz

    2018-02-01

    The study examines the potential of urban roofs to reduce the urban heat island (UHI) effect by changing their reflectivity and implementing vegetation (green roofs) using the example of the City of Vienna. The urban modelling simulations are performed based on high-resolution orography and land use data, climatological observations, surface albedo values from satellite imagery and registry of the green roof potential in Vienna. The modelling results show that a moderate increase in reflectivity of roofs (up to 0.45) reduces the mean summer temperatures in the densely built-up environment by approximately 0.25 °C. Applying high reflectivity materials (roof albedo up to 0.7) leads to average cooling in densely built-up area of approximately 0.5 °C. The green roofs yield a heat load reduction in similar order of magnitude as the high reflectivity materials. However, only 45 % of roof area in Vienna is suitable for greening and the green roof potential mostly applies to industrial areas in city outskirts and is therefore not sufficient for substantial reduction of the UHI effect, particularly in the city centre which has the highest heat load. The strongest cooling effect can be achieved by combining the green roofs with high reflectivity materials. In this case, using 50 or 100 % of the green roof potential and applying high reflectivity materials on the remaining surfaces have a similar cooling effect.

  7. Male sexual strategies modify ratings of female models with specific waist-to-hip ratios.

    Science.gov (United States)

    Brase, Gary L; Walker, Gary

    2004-06-01

    Female waist-to-hip ratio (WHR) has generally been an important general predictor of ratings of physical attractiveness and related characteristics. Individual differences in ratings do exist, however, and may be related to differences in the reproductive tactics of the male raters such as pursuit of short-term or long-term relationships and adjustments based on perceptions of one's own quality as a mate. Forty males, categorized according to sociosexual orientation and physical qualities (WHR, Body Mass Index, and self-rated desirability), rated female models on both attractiveness and likelihood they would approach them. Sociosexually restricted males were less likely to approach females rated as most attractive (with 0.68-0.72 WHR), as compared with unrestricted males. Males with lower scores in terms of physical qualities gave ratings indicating more favorable evaluations of female models with lower WHR. The results indicate that attractiveness and willingness to approach are overlapping but distinguishable constructs, both of which are influenced by variations in characteristics of the raters.

  8. The FFA dynamic stall model. The Beddoes-Leishman dynamic stall model modified for lead-lag oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerck, A. [FFA, The Aeronautical Research Institute of Sweden, Bromma (Sweden)

    1997-08-01

    For calculations of the dynamics of wind turbines the inclusion of a dynamic stall model is necessary in order to obtain reliable results at high winds. For blade vibrations in the lead-lag motion the velocity relative to the blade will vary in time. In the present paper modifications to the Beddoes-Leishman model is presented in order to improve the model for calculations of cases with a varying relative velocity. Comparisons with measurement are also shown and the influence on the calculated aerodynamic damping by the modifications are investigated. (au)

  9. Geometry and time scales of self-consistent orbits in a modified SU(2) model

    International Nuclear Information System (INIS)

    Jezek, D.M.; Hernandez, E.S.; Solari, H.G.

    1986-01-01

    We investigate the time-dependent Hartree-Fock flow pattern of a two-level many fermion system interacting via a two-body interaction which does not preserve the parity symmetry of standard SU(2) models. The geometrical features of the time-dependent Hartree-Fock energy surface are analyzed and a phase instability is clearly recognized. The time evolution of one-body observables along self-consistent and exact trajectories are examined together with the overlaps between both orbits. Typical time scales for the determinantal motion can be set and the validity of the time-dependent Hartree-Fock approach in the various regions of quasispin phase space is discussed

  10. Modified stretched exponential model of computer system resources management limitations-The case of cache memory

    Science.gov (United States)

    Strzałka, Dominik; Dymora, Paweł; Mazurek, Mirosław

    2018-02-01

    In this paper we present some preliminary results in the field of computer systems management with relation to Tsallis thermostatistics and the ubiquitous problem of hardware limited resources. In the case of systems with non-deterministic behaviour, management of their resources is a key point that guarantees theirs acceptable performance and proper working. This is very wide problem that stands for many challenges in financial, transport, water and food, health, etc. areas. We focus on computer systems with attention paid to cache memory and propose to use an analytical model that is able to connect non-extensive entropy formalism, long-range dependencies, management of system resources and queuing theory. Obtained analytical results are related to the practical experiment showing interesting and valuable results.

  11. Myocardial regeneration by transplantation of modified endothelial progenitor cells expressing SDF-1 in a rat model

    DEFF Research Database (Denmark)

    Schuh, A.; Kroh, A.; Konschalla, S.

    2012-01-01

    Cell based therapy has been shown to attenuate myocardial dysfunction after myocardial infarction (MI) in different acute and chronic animal models. It has been further shown that stromal-cell derived factor-1a (SDF-1a) facilitates proliferation and migration of endogenous progenitor cells...... into injured tissue. The aim of the present study was to investigate the role of exogenously applied and endogenously mobilized cells in a regenerative strategy for MI therapy. Lentivirally SDF-1a-infected endothelial progenitor cells (EPCs) were injected after 90 min. of ligation and reperfusion of the left...... compared to medium control. Intracoronary application of cells did not lead to significant differences compared to medium injected control hearts. Histology showed a significantly elevated rate of apoptotic cells and augmented proliferation after transplantation of EPCs and EPCs + SDF-1 alpha in infarcted...

  12. Local re-acceleration and a modified thick target model of solar flare electrons

    Science.gov (United States)

    Brown, J. C.; Turkmani, R.; Kontar, E. P.; MacKinnon, A. L.; Vlahos, L.

    2009-12-01

    Context: The collisional thick target model (CTTM) of solar hard X-ray (HXR) bursts has become an almost “standard model” of flare impulsive phase energy transport and radiation. However, it faces various problems in the light of recent data, particularly the high electron beam density and anisotropy it involves. Aims: We consider how photon yield per electron can be increased, and hence fast electron beam intensity requirements reduced, by local re-acceleration of fast electrons throughout the HXR source itself, after injection. Methods: We show parametrically that, if net re-acceleration rates due to e.g. waves or local current sheet electric (E) fields are a significant fraction of collisional loss rates, electron lifetimes, and hence the net radiative HXR output per electron can be substantially increased over the CTTM values. In this local re-acceleration thick target model (LRTTM) fast electron number requirements and anisotropy are thus reduced. One specific possible scenario involving such re-acceleration is discussed, viz, a current sheet cascade (CSC) in a randomly stressed magnetic loop. Results: Combined MHD and test particle simulations show that local E fields in CSCs can efficiently accelerate electrons in the corona and and re-accelerate them after injection into the chromosphere. In this HXR source scenario, rapid synchronisation and variability of impulsive footpoint emissions can still occur since primary electron acceleration is in the high Alfvén speed corona with fast re-acceleration in chromospheric CSCs. It is also consistent with the energy-dependent time-of-flight delays in HXR features. Conclusions: Including electron re-acceleration in the HXR source allows an LRTTM modification of the CTTM in which beam density and anisotropy are much reduced, and alleviates theoretical problems with the CTTM, while making it more compatible with radio and interplanetary electron numbers. The LRTTM is, however, different in some respects such as

  13. Modifying the baricity of local anesthetics for spinal anesthesia by temperature adjustment: model calculations.

    Science.gov (United States)

    Heller, Axel R; Zimmermann, Katrin; Seele, Kristin; Rössel, Thomas; Koch, Thea; Litz, Rainer J

    2006-08-01

    Although local anesthetics (LAs) are hyperbaric at room temperature, density drops within minutes after administration into the subarachnoid space. LAs become hypobaric and therefore may cranially ascend during spinal anesthesia in an uncontrolled manner. The authors hypothesized that temperature and density of LA solutions have a nonlinear relation that may be described by a polynomial equation, and that conversion of this equation may provide the temperature at which individual LAs are isobaric. Density of cerebrospinal fluid was measured using a vibrating tube densitometer. Temperature-dependent density data were obtained from all LAs commonly used for spinal anesthesia, at least in triplicate at 5 degrees, 20 degrees, 30 degrees, and 37 degrees C. The hypothesis was tested by fitting the obtained data into polynomial mathematical models allowing calculations of substance-specific isobaric temperatures. Cerebrospinal fluid at 37 degrees C had a density of 1.000646 +/- 0.000086 g/ml. Three groups of local anesthetics with similar temperature (T, degrees C)-dependent density (rho) characteristics were identified: articaine and mepivacaine, rho1(T) = 1.008-5.36 E-06 T2 (heavy LAs, isobaric at body temperature); L-bupivacaine, rho2(T) = 1.007-5.46 E-06 T2 (intermediate LA, less hypobaric than saline); bupivacaine, ropivacaine, prilocaine, and lidocaine, rho3(T) = 1.0063-5.0 E-06 T (light LAs, more hypobaric than saline). Isobaric temperatures (degrees C) were as follows: 5 mg/ml bupivacaine, 35.1; 5 mg/ml L-bupivacaine, 37.0; 5 mg/ml ropivacaine, 35.1; 20 mg/ml articaine, 39.4. Sophisticated measurements and mathematic models now allow calculation of the ideal injection temperature of LAs and, thus, even better control of LA distribution within the cerebrospinal fluid. The given formulae allow the adaptation on subpopulations with varying cerebrospinal fluid density.

  14. Theoretical modelling of epigenetically modified DNA sequences [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Alexandra Teresa Pires Carvalho

    2015-05-01

    Full Text Available We report herein a set of calculations designed to examine the effects of epigenetic modifications on the structure of DNA. The incorporation of methyl, hydroxymethyl, formyl and carboxy substituents at the 5-position of cytosine is shown to hardly affect the geometry of CG base pairs, but to result in rather larger changes to hydrogen-bond and stacking binding energies, as predicted by dispersion-corrected density functional theory (DFT methods. The same modifications within double-stranded GCG and ACA trimers exhibit rather larger structural effects, when including the sugar-phosphate backbone as well as sodium counterions and implicit aqueous solvation. In particular, changes are observed in the buckle and propeller angles within base pairs and the slide and roll values of base pair steps, but these leave the overall helical shape of DNA essentially intact. The structures so obtained are useful as a benchmark of faster methods, including molecular mechanics (MM and hybrid quantum mechanics/molecular mechanics (QM/MM methods. We show that previously developed MM parameters satisfactorily reproduce the trimer structures, as do QM/MM calculations which treat bases with dispersion-corrected DFT and the sugar-phosphate backbone with AMBER. The latter are improved by inclusion of all six bases in the QM region, since a truncated model including only the central CG base pair in the QM region is considerably further from the DFT structure. This QM/MM method is then applied to a set of double-stranded DNA heptamers derived from a recent X-ray crystallographic study, whose size puts a DFT study beyond our current computational resources. These data show that still larger structural changes are observed than in base pairs or trimers, leading us to conclude that it is important to model epigenetic modifications within realistic molecular contexts.

  15. Modified impact of emotion on temporal discrimination in a transgenic rat model of Huntington disease

    Directory of Open Access Journals (Sweden)

    Alexis eFaure

    2013-09-01

    Full Text Available Huntington’s disease (HD is characterized by triad of motor, cognitive and emotional symptoms along with neuropathology in fronto-striatal circuit and limbic system including amygdala. Emotional alterations, which have a negative impact on patient well-being, represent some of the earliest symptoms of HD and might be related to the onset of the neurodegenerative process. In the transgenic rat model (tgHD rats, evidence suggest emotional alterations at the symptomatic stage along with neuropathology of the central nucleus of amygdala (CE. Studies in humans and animals demonstrate that emotion can modulate time perception. The impact of emotion on time perception has never been tested in HD, nor is it known if that impact could be part of the presymptomatic emotional phenotype of the pathology. The aim of this paper was to characterize the effect of emotion on temporal discrimination in presymptomatic tgHD animals. In the first experiment, we characterized the acute effect of an emotion (fear conditioned stimulus on temporal discrimination using a bisection procedure, and tested its dependency upon an intact central amygdala. The second experiment was aimed at comparing presymptomatic homozygous transgenic animals at 7-months of age and their wild-type littermates (WT in their performance on the modulation of temporal discrimination by emotion. Our principal findings show that (1 a fear cue produces a short-lived decrease of temporal precision after its termination, and (2 animals with medial CE lesion and presymptomatic tgHD animals demonstrate an alteration of this emotion-evoked temporal distortion. The results contribute to our knowledge about the presymptomatic phenotype of this HD rat model, showing susceptibility to emotion that may be related to dysfunction of the central nucleus of amygdala.

  16. Modeling the effects of cooling rate, hydrogen content, grain refiner and modifier on microporosity formation in Al A356 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Conley, J.G.; Huang, J.; Asada, J.; Akiba, K. [Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering

    2000-06-15

    Cast Aluminum-Silicon alloys are used in numerous automotive and industrial weight sensitive applications because of their low density and excellent castability. The presence of trapped gas and or shrinkage pores in certain locations within castings has been shown to influence fatigue life. These micromechanical defects can be found most anywhere in a casting depending on processing conditions. A large amount of porosity located in the center of the cast material thickness may have no effect on mechanical properties or fatigue performance. A smaller, isolated pore near a surface may have a significant impact on mechanical properties. Hence, it is important to develop a comprehensive model to predict the size, location and distribution of microporosity in castings. In this work, we model the effect of various casting process parameters on microporosity formation for aluminum A356 alloy castings. The process parameters include cooling rate, hydrogen content, grain refiner and modifier. The proposed two-dimensional model predicts the size, morphology and distribution of microporosity at a given location in the casting. The method couples a mathematical model of porosity evolution with a probabilistic grain structure prediction model. The porosity evolution model is based on the simultaneous solution of the continuity and momentum equations for the metal and the mass conservation equation for the dissolved gas. The nucleation and growth of grains are simulated with a probabilistic method that uses the information from a heat transfer simulation, i.e. temperature and solid fraction, to determine the transition rules for grain evolution. The simulation results correlate well with experimental observation of porosity in cast structures. (orig.)

  17. A Modified Thermal Time Model Quantifying Germination Response to Temperature for C3 and C4 Species in Temperate Grassland

    Directory of Open Access Journals (Sweden)

    Hongxiang Zhang

    2015-07-01

    Full Text Available Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C4 and 15 C3 species were germinated at a range of constant temperatures from 5 °C to 40 °C. We used a modified thermal time model to calculate germination parameters at suboptimal temperatures. Generally, the optimal germination temperature was higher for C4 species than for C3 species. The thermal time constant for the 50% germination percentile was significantly higher for C3 than C4 species. The thermal time constant of perennials was significantly higher than that of annuals. However, differences in base temperatures were not significant between C3 and C4, or annuals and perennial species. The relationship between germination rate and seed mass depended on plant functional type and temperature, while the base temperature and thermal time constant of C3 and C4 species exhibited no significant relationship with seed mass. The results illustrate differences in germination characteristics between C3 and C4 species. Seed mass does not affect germination parameters, plant life cycle matters, however.

  18. Fog prediction using the modified asymptotic liquid water content vertical distribution formulation with the Weather Research and Forecasting model

    Science.gov (United States)

    Kim, E.; Lee, S.; Kim, J.; Chae, D.

    2017-12-01

    Fog forecasts have difficulty in forecasting due to temporal and spatial resolution problems, high numerical computations, complicated mechanisms related to turbulence in order to analyze the fog in the model, and a lack of appropriate fog physical processes. Conventional fog prediction is based on the surface visibility threshold "fog diagnosis method is based on the fog related variables near the surface, such as visibility, low stratus, relative humidity and wind speed but this method only predicts fog occurrence not fog intensity. To improve this, a new fog diagnostic scheme, based on an asymptotic analytical study of radiation fog (Zhou and Ferrier 2008, ZF08) is to increase the accuracy of fog prediction by calculating the vertical LWC considering cooling, turbulence and droplet settling, visibility, surface relative humidity and low stratus. In this study, we intend to improve fog prediction through the Weather Research and Forecasting (WRF) model using high-resolution data. Although the prediction accuracy can be improved by combining the WRF Planetary Boundary Layer (PBL) scheme and 1 dimension (1D) model, it is necessary to increase the vertical resolution in the boundary layer to implement the fog formation and persistence mechanism in the internal boundary layer in the PBL more accurately, we'll modify the algorithm to enhance the effects of turbulence and then compare the newly predicted fog and observations to determine the accuracy of the forecast of the fog occurring on the Korean peninsula.

  19. C. elegans model identifies genetic modifiers of alpha-synuclein inclusion formation during aging.

    Directory of Open Access Journals (Sweden)

    Tjakko J van Ham

    2008-03-01

    Full Text Available Inclusions in the brain containing alpha-synuclein are the pathological hallmark of Parkinson's disease, but how these inclusions are formed and how this links to disease is poorly understood. We have developed a C. elegans model that makes it possible to monitor, in living animals, the formation of alpha-synuclein inclusions. In worms of old age, inclusions contain aggregated alpha- synuclein, resembling a critical pathological feature. We used genome-wide RNA interference to identify processes involved in inclusion formation, and identified 80 genes that, when knocked down, resulted in a premature increase in the number of inclusions. Quality control and vesicle-trafficking genes expressed in the ER/Golgi complex and vesicular compartments were overrepresented, indicating a specific role for these processes in alpha-synuclein inclusion formation. Suppressors include aging-associated genes, such as sir-2.1/SIRT1 and lagr-1/LASS2. Altogether, our data suggest a link between alpha-synuclein inclusion formation and cellular aging, likely through an endomembrane-related mechanism. The processes and genes identified here present a framework for further study of the disease mechanism and provide candidate susceptibility genes and drug targets for Parkinson's disease and other alpha-synuclein related disorders.

  20. Nonlinear dynamics of the m=1 kink-tearing instability in a modified magnetohydrodynamic model

    International Nuclear Information System (INIS)

    Wang, X.; Bhattacharjee, A.

    1995-01-01

    A theory is given for the nonlinear dynamical evolution of the collisionless m=1 kink-tearing instability, including the effects of electron inertia and electron pressure gradient in a generalized Ohm's law. It is demonstrated that electron pressure gradients can cause near-explosive growth in the nonlinear regime of a thin m=1 island. This near-explosive phase is followed by a rapid decay phase as the island width becomes comparable to the radius of the sawtooth region. An island equation is derived for the entire nonlinear evolution of the instability, extending recent work on the subject [X. Wang and A. Bhattacharjee, Phys. Rev. Lett. 70, 1627 (1993)] to include the effects of both electron inertia and electron pressure gradient. Comparisons are made with experimental data from present-day tokamaks. It is suggested that the present model not only accounts for fast sawtooth crashes, but also provides possible explanations for the problems of sudden onset and incomplete reconnection that have been, heretofore, unexplained features of observations. copyright 1995 American Institute of Physics

  1. Numerical simulation of coal gasification process using the modifying Watanabe - Otaka model.

    Energy Technology Data Exchange (ETDEWEB)

    T. Papadopoulos; M. Losurdo; H. Spliethoff

    2009-07-01

    High-pressure entrained flow coal gasification is becoming increasingly important particularly in the development of Integrated Coal Gasification Combined Cycle (IGCC) technology for the production of electricity. However, there is a lack of knowledge worldwide for the gasification process and more especially for the chemical reactions (reactions rates) that take place under high pressure and temperature. Therefore a gasifier has been designed and is being built at the Institute for Energy Systems (Lehrstuhl fuer Energisysteme - LES) at the Technische Universitaet Muenchen (TUM). This gasifier is an entrained flow gasifier and has the advantage that it can operate to very high conditions of pressure and temperature, up to 50 bar pressure and 1800{sup o}C temperature. In an ongoing project, a great variety of experiments are planned to determine chemical reactions rates at high pressure conditions. In addition to the experimental work, CFD numerical simulations of pulverized coal gasification are being performed. The aim is to use numerical investigations for preliminary assessment of the facility. The goal is to develop a gasification model suitable for high pressure and condition tailored on the experiments to be used in CFD computations to predict chemical reactions, the heat transfer and the turbulence inside the gasifier. 9 refs., 2 figs., 2 tabs.

  2. Modified model of VX2 tumor overexpressing vascular endothelial growth factor.

    Science.gov (United States)

    Pascale, Florentina; Ghegediban, Saida-Homayra; Bonneau, Michel; Bedouet, Laurent; Namur, Julien; Verret, Valentin; Schwartz-Cornil, Isabelle; Wassef, Michel; Laurent, Alexandre

    2012-06-01

    To determine whether upregulated expression of vascular endothelial growth factor (VEGF) in VX2 cells can increase vessel density (VD) and reduce tumor necrosis. The VX2 cell line was transfected with expression vectors containing cDNA for rabbit VEGF. Stable clones producing rabbit VEGF (VEGF-VX2) were selected. VEGF-VX2 cells (n = 5 rabbits) or nontransfected VX2 cells (controls; n = 5 rabbits) were implanted into leg muscle of 10 rabbits. The animals were sacrificed at day 21. Tumor volume, percentage of necrosis, VD, and VEGF concentration in tumor protein extract were quantified. Overexpression of VEGF by VX2 cells augmented tumor implantation efficiency 100% and favored cyst formation. The tumor volume was significantly larger for VEGF-VX2 transfected tumors versus controls (P = .0143). Overexpression of VEGF in VX2 cells significantly increased the VD of the tumors (P = .0138). The percentage of necrosis was reduced in VEGF-VX2 tumors versus controls (19.5% vs 38.5 %; P = .002). VEGF concentration in VEGF-VX2 tumors was significantly higher than in control tumors (P = .041) and was correlated with tumor volume (ρ = .883, P = .012). The overexpression of VEGF increased tumor growth and vascularization, favored cyst formation, and reduced tumor necrosis. This new phenotype of the VX2 tumor may offer some advantages over classic models of VX2 tumor for evaluating anticancer therapies. Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.

  3. A modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model for predicting liquid viscosity of pure organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seongmin; Park, Kiho; Yang, Dae Ryook [Korea University, Seoul (Korea, Republic of); Kwon, Yunkyung; Park, Taeyun [ChemEssen Inc., Seoul (Korea, Republic of)

    2017-10-15

    Liquid viscosity is an important physical property utilized in engineering designs for transportation and processing of fluids. However, the measurement of liquid viscosity is not always easy when the materials have toxicity and instability. In this study, a modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model is suggested and analyzed in terms of its performance of prediction for liquid viscosity compared to the conventional SVRC-QSPR model and the other methods. The modification was conducted by changing the initial point from triple point to ambient temperature (293 K), and assuming that the liquid viscosity at critical temperature is 0 cP. The results reveal that the prediction performance of the modified SVRC-QSPR model is comparable to the other methods as showing 7.90% of mean absolute percentage error (MAPE) and 0.9838 of R{sup 2}. In terms of both the number of components and the performance of prediction, the modified SVRC-QSPR model is superior to the conventional SVRC-QSPR model. Also, the applicability of the model is improved since the condition of the end points of the modified model is not so restrictive as the conventional SVRC-QSPR model.

  4. A modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model for predicting liquid viscosity of pure organic compounds

    International Nuclear Information System (INIS)

    Lee, Seongmin; Park, Kiho; Yang, Dae Ryook; Kwon, Yunkyung; Park, Taeyun

    2017-01-01

    Liquid viscosity is an important physical property utilized in engineering designs for transportation and processing of fluids. However, the measurement of liquid viscosity is not always easy when the materials have toxicity and instability. In this study, a modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model is suggested and analyzed in terms of its performance of prediction for liquid viscosity compared to the conventional SVRC-QSPR model and the other methods. The modification was conducted by changing the initial point from triple point to ambient temperature (293 K), and assuming that the liquid viscosity at critical temperature is 0 cP. The results reveal that the prediction performance of the modified SVRC-QSPR model is comparable to the other methods as showing 7.90% of mean absolute percentage error (MAPE) and 0.9838 of R 2 . In terms of both the number of components and the performance of prediction, the modified SVRC-QSPR model is superior to the conventional SVRC-QSPR model. Also, the applicability of the model is improved since the condition of the end points of the modified model is not so restrictive as the conventional SVRC-QSPR model.

  5. Plants modify biological processes to ensure survival following carbon depletion: a Lolium perenne model.

    Directory of Open Access Journals (Sweden)

    Julia M Lee

    Full Text Available BACKGROUND: Plants, due to their immobility, have evolved mechanisms allowing them to adapt to multiple environmental and management conditions. Short-term undesirable conditions (e.g. moisture deficit, cold temperatures generally reduce photosynthetic carbon supply while increasing soluble carbohydrate accumulation. It is not known, however, what strategies plants may use in the long-term to adapt to situations resulting in net carbon depletion (i.e. reduced photosynthetic carbon supply and carbohydrate accumulation. In addition, many transcriptomic experiments have typically been undertaken under laboratory conditions; therefore, long-term acclimation strategies that plants use in natural environments are not well understood. METHODOLOGY/PRINCIPAL FINDINGS: Perennial ryegrass (Lolium perenne L. was used as a model plant to define whether plants adapt to repetitive carbon depletion and to further elucidate their long-term acclimation mechanisms. Transcriptome changes in both lamina and stubble tissues of field-grown plants with depleted carbon reserves were characterised using reverse transcription-quantitative polymerase chain reaction (RT-qPCR. The RT-qPCR data for select key genes indicated that plants reduced fructan degradation, and increased photosynthesis and fructan synthesis capacities following carbon depletion. This acclimatory response was not sufficient to prevent a reduction (P<0.001 in net biomass accumulation, but ensured that the plant survived. CONCLUSIONS: Adaptations of plants with depleted carbon reserves resulted in reduced post-defoliation carbon mobilization and earlier replenishment of carbon reserves, thereby ensuring survival and continued growth. These findings will help pave the way to improve plant biomass production, for either grazing livestock or biofuel purposes.

  6. Modifying conjoint methods to model managers' reactions to business environmental trends : an application to modeling retailer reactions to sales trends

    NARCIS (Netherlands)

    Oppewal, H.; Louviere, J.J.; Timmermans, H.J.P.

    2000-01-01

    This article proposes and demonstrates how conjoint methods can be adapted to allow the modeling of managerial reactions to various changes in economic and competitive environments and their effects on observed sales levels. Because in general micro-level data on strategic decision making over time

  7. Dry thermophilic semi-continuous anaerobic digestion of food waste: Performance evaluation, modified Gompertz model analysis, and energy balance

    International Nuclear Information System (INIS)

    Nguyen, Dinh Duc; Chang, Soon Woong; Jeong, Seong Yeob; Jeung, Jaehoon; Kim, Sungsu; Guo, Wenshan; Ngo, Huu Hao

    2016-01-01

    Highlights: • Energy self-sufficiency/energy recovery with thermophilic DScAD of FW was evaluated. • The maximum biogas production rate was positively influenced by OLRs. • Maximum (average) electrical energy recoverable from a 1 tons of FW was 1050 kW h. • Thermophilic DScAD can substantially reduce the VS and recover energy to serve itself. • A modified Gompertz model fitted well with the experimental results for all phases. - Abstract: A thermophilic, dry semi-continuous anaerobic digestion (DScAD) method was used to effectively transform food waste (FW) into renewable energy. This study aims to thoroughly evaluate the system performance and model simulation to predict biogas production, intermediate products and their outcomes, energy recovery potential, and energy balance, while operating with organic loading rates ranging from 2.3 to 9.21 kg-TS/m"3 day. The results indicate that volatile solids (VS) reduction and biogas production both improved as the organic loading rates (OLR) increased, and the cost of FW valorization remained low. The greatest VS reduction achieved was 87.01%, associated with 170 m"3 of biogas yield per ton of sludge (69% methane) at an ORL of 9.21 ± 0.89 kg-TS/m"3 day (8.62 ± 0.34 kg-VS/m"3 day) although the amounts of ammonia (3700 mg/L), hydrogen sulfide (420 ppm), and total volatile fatty acids (7101 mg/L) during fermentation were relatively high. Furthermore, 75% of total energy requirement for the system could be recovered via biomethane production, resulting in a considerably reduced specific energy supply (kW h/ton of treating FW). The results suggest that a modified Gompertz model is suitable for estimating the biogas and methane production potential and rate. The results also reveal that the DScAD of FW at 55 °C is a reliable, stable, and robust option for both solids reduction and energy recovery via biogas generation.

  8. A modified model for estimation of daylight factor for skylight integrated with dome roof structure of mud-house in New Delhi (India)

    Energy Technology Data Exchange (ETDEWEB)

    Chel, Arvind; Tiwari, G.N.; Singh, H.N. [Centre for Energy Studies (CES), Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016 (India)

    2010-10-15

    The daylight factor model given by Charted Institute of Building Services Engineers (CIBSE) was modified in this paper to incorporate time variations with respect to zenith angle ({theta}{sub z}) and vertical height (h) of working surface above ground surface which was normalized with central height (H) of skylight dome. The modified model contains constant exponents which are determined using linear regression analysis based on hourly experimental data of inside and outside illuminance for each month of the year 2007-2008. The prediction of modified model is found in good agreement with experimental observed inside illuminance data on the basis of values of root mean square percentage error (e) and correlation coefficient (r). The annual average daylight factor values for big and small dome skylight rooms are determined as 2.3% and 4.4% respectively. The energy saving potential of skylight rooms for selected climatic locations in India is also presented in this paper. (author)

  9. A modified Wright-Fisher model that incorporates Ne: A variant of the standard model with increased biological realism and reduced computational complexity.

    Science.gov (United States)

    Zhao, Lei; Gossmann, Toni I; Waxman, David

    2016-03-21

    The Wright-Fisher model is an important model in evolutionary biology and population genetics. It has been applied in numerous analyses of finite populations with discrete generations. It is recognised that real populations can behave, in some key aspects, as though their size that is not the census size, N, but rather a smaller size, namely the effective population size, Ne. However, in the Wright-Fisher model, there is no distinction between the effective and census population sizes. Equivalently, we can say that in this model, Ne coincides with N. The Wright-Fisher model therefore lacks an important aspect of biological realism. Here, we present a method that allows Ne to be directly incorporated into the Wright-Fisher model. The modified model involves matrices whose size is determined by Ne. Thus apart from increased biological realism, the modified model also has reduced computational complexity, particularly so when Ne⪡N. For complex problems, it may be hard or impossible to numerically analyse the most commonly-used approximation of the Wright-Fisher model that incorporates Ne, namely the diffusion approximation. An alternative approach is simulation. However, the simulations need to be sufficiently detailed that they yield an effective size that is different to the census size. Simulations may also be time consuming and have attendant statistical errors. The method presented in this work may then be the only alternative to simulations, when Ne differs from N. We illustrate the straightforward application of the method to some problems involving allele fixation and the determination of the equilibrium site frequency spectrum. We then apply the method to the problem of fixation when three alleles are segregating in a population. This latter problem is significantly more complex than a two allele problem and since the diffusion equation cannot be numerically solved, the only other way Ne can be incorporated into the analysis is by simulation. We have

  10. The exercise and affect relationship: evidence for the dual-mode model and a modified opponent process theory.

    Science.gov (United States)

    Markowitz, Sarah M; Arent, Shawn M

    2010-10-01

    This study examined the relationship between exertion level and affect using the framework of opponent-process theory and the dual-mode model, with the Activation-Deactivation Adjective Checklist and the State Anxiety Inventory among 14 active and 14 sedentary participants doing 20 min of treadmill exercise at speeds of 5% below, 5% above, and at lactate threshold (LT). We found a significant effect of time, condition, Time × Condition, and Time × Group, but no group, Group × Condition, or Time × Group × Condition effects, such that the 5% above LT condition produced a worsening of affect in-task compared with all other conditions whereas, across conditions, participants experienced in-task increases in energy and tension, and in-task decreases in tiredness and calmness relative to baseline. Posttask, participants experienced mood improvement (decreased tension, anxiety, and increased calmness) across conditions, with a 30-min delay in the above LT condition. These results partially support the dual-mode model and a modified opponent-process theory.

  11. Hyaluronic Acid-Modified Magnetic Iron Oxide Nanoparticles for MR Imaging of Surgically Induced Endometriosis Model in Rats

    Science.gov (United States)

    Sun, Wenjie; Hu, Yong; Zhang, Guofu; Shen, Mingwu; Shi, Xiangyang

    2014-01-01

    Endometriosis is defined as the presence of endometrial tissue outside the uterine, which may affect nearly 60% of women in reproductive age. Deep infiltrating endometriosis (DIE) defined as an endometriotic lesion penetrating into the retroperitoneal space or the wall of the pelvic organs to a depth of at least 5 mm represents the most diagnostic challenge. Herein, we reported the use of hyaluronic acid (HA)-modified magnetic iron oxide nanoparticles (HA-Fe3O4 NPs) for magnetic resonance (MR) imaging of endometriotic lesions in the rodent model. Sixteen endometriotic lesions were surgically induced in eight rats by autologous transplantation. Four weeks after lesion induction, three rats were scanned via MR imaging after tail vein injection of the HA-Fe3O4 NPs. Accordingly, the remaining five mice were sacrificed in the corresponding time points. The ectopic uterine tissues (EUTs) were confirmed by histological analysis. Quantification of Fe in the EUT was also performed by inductively coupled plasma-optical emission spectroscopy. Our results showed that by using the HA-Fe3O4 NPs, the EUTs were able to be visualized via T2-weighted MR imaging at 2 hours post injection, corroborating the Prussian blue staining results. The developed HA-Fe3O4 NPs could be used as negative contrast agents for sensitively detecting endometriosis in a mouse model and may be applied for future hyperthermia treatment of endometriosis. PMID:24722347

  12. Hyaluronic acid-modified magnetic iron oxide nanoparticles for MR imaging of surgically induced endometriosis model in rats.

    Directory of Open Access Journals (Sweden)

    He Zhang

    Full Text Available Endometriosis is defined as the presence of endometrial tissue outside the uterine, which may affect nearly 60% of women in reproductive age. Deep infiltrating endometriosis (DIE defined as an endometriotic lesion penetrating into the retroperitoneal space or the wall of the pelvic organs to a depth of at least 5 mm represents the most diagnostic challenge. Herein, we reported the use of hyaluronic acid (HA-modified magnetic iron oxide nanoparticles (HA-Fe3O4 NPs for magnetic resonance (MR imaging of endometriotic lesions in the rodent model. Sixteen endometriotic lesions were surgically induced in eight rats by autologous transplantation. Four weeks after lesion induction, three rats were scanned via MR imaging after tail vein injection of the HA-Fe3O4 NPs. Accordingly, the remaining five mice were sacrificed in the corresponding time points. The ectopic uterine tissues (EUTs were confirmed by histological analysis. Quantification of Fe in the EUT was also performed by inductively coupled plasma-optical emission spectroscopy. Our results showed that by using the HA-Fe3O4 NPs, the EUTs were able to be visualized via T2-weighted MR imaging at 2 hours post injection, corroborating the Prussian blue staining results. The developed HA-Fe3O4 NPs could be used as negative contrast agents for sensitively detecting endometriosis in a mouse model and may be applied for future hyperthermia treatment of endometriosis.

  13. Modified Wagner model for the active-to-passive transition in the oxidation of Si3N4

    International Nuclear Information System (INIS)

    Wang Junjie; Zhang Litong; Zeng Qingfeng; Cheng Laifei; Xu Yongdong

    2008-01-01

    Si 3 N 4 is used as the coating material of space shuttle structures which receive very high thermal fluxes during the atmospheric re-entry phase. Two main regimes govern the oxidation of Si 3 N 4 : the passive oxidation, with the formation of a protective silica layer leading generally to a mass gain, and the active oxidation, with vaporization of SiO leading to a mass loss of the sample. To ensure that silicon nitride will efficiently protect a material in given oxidizing environments, its own oxidation behaviour must be previously known. Therefore, the active-to-passive transition of Si 3 N 4 oxidation is a problem of deep scientific importance and of wide technological relevance. In this paper, a modified Wager model for the active-to-passive transition in the oxidation of Si 3 N 4 is presented, which includes the non-equilibrium effects caused by the mass transfer. The present theoretical calculations satisfactorily explained the reported experimental and theoretical data. The influence of flow rate on the active-to-passive transition boundary has been explained using our model. The rate controlling mechanism of the oxidation at the active-to-passive transition point is proposed

  14. Dynamic properties of polydisperse colloidal particles in the presence of thermal gradient studied by a modified Brownian dynamic model

    Science.gov (United States)

    Song, Dongxing; Jin, Hui; Jing, Dengwei; Wang, Xin

    2018-03-01

    Aggregation and migration of colloidal particles under the thermal gradient widely exists in nature and many industrial processes. In this study, dynamic properties of polydisperse colloidal particles in the presence of thermal gradient were studied by a modified Brownian dynamic model. Other than the traditional forces on colloidal particles, including Brownian force, hydrodynamic force, and electrostatic force from other particles, the electrostatic force from the asymmetric ionic diffusion layer under a thermal gradient has been considered and introduced into the Brownian dynamic model. The aggregation ratio of particles (R A), the balance time (t B) indicating the time threshold when {{R}A} becomes constant, the porosity ({{P}BA} ), fractal dimension (D f) and distributions of concentration (DISC) and aggregation (DISA) for the aggregated particles were discussed based on this model. The aggregated structures formed by polydisperse particles are less dense and the particles therein are loosely bonded. Also it showed a quite large compressibility as the increases of concentration and interparticle potential can significantly increase the fractal dimension. The thermal gradient can induce two competitive factors leading to a two-stage migration of particles. When t{{t}B} , the thermophoresis becomes dominant thus the migrations of particles are against the thermal gradient. The effect of thermophoresis on the aggregate structures was found to be similar to the effect of increasing particle concentration. This study demonstrates how the thermal gradient affects the aggregation of monodisperse and polydisperse particles and can be a guide for the biomimetics and precise control of colloid system under the thermal gradient. Moreover, our model can be easily extended to other more complex colloidal systems considering shear, temperature fluctuation, surfactant, etc.

  15. Estimation of (Cl-Mn) /Fe flux ratio at relativistic energies using steady-state leaky-box model modified for re accelerations

    International Nuclear Information System (INIS)

    Majumdar, R.; Basu, B.; Bhattacharyya, D.P.

    1997-01-01

    The (Cl-Mn) /Fe flux ratio at the top of the atmosphere has been estimated from source composition. The authors have adopted the SSLB model modified for weak shocks to estimate the enhancement of (Cl-Mn) /Fe flux ratio due to re acceleration. The observed active detector results of Lezniak and Webber, Caldwell, Orth et al., Engelmann et al., and our passive detector results are fairly supported by the expected results from the SSLB model modified with re acceleration after Ferrando for energies ≤ 100 GeV / n

  16. Modified social ecological model: a tool to guide the assessment of the risks and risk contexts of HIV epidemics.

    Science.gov (United States)

    Baral, Stefan; Logie, Carmen H; Grosso, Ashley; Wirtz, Andrea L; Beyrer, Chris

    2013-05-17

    Social and structural factors are now well accepted as determinants of HIV vulnerabilities. These factors are representative of social, economic, organizational and political inequities. Associated with an improved understanding of multiple levels of HIV risk has been the recognition of the need to implement multi-level HIV prevention strategies. Prevention sciences research and programming aiming to decrease HIV incidence requires epidemiologic studies to collect data on multiple levels of risk to inform combination HIV prevention packages. Proximal individual-level risks, such as sharing injection devices and unprotected penile-vaginal or penile-anal sex, are necessary in mediating HIV acquisition and transmission. However, higher order social and structural-level risks can facilitate or reduce HIV transmission on population levels. Data characterizing these risks is often far more actionable than characterizing individual-level risks. We propose a modified social ecological model (MSEM) to help visualize multi-level domains of HIV infection risks and guide the development of epidemiologic HIV studies. Such a model may inform research in epidemiology and prevention sciences, particularly for key populations including men who have sex with men (MSM), people who inject drugs (PID), and sex workers. The MSEM builds on existing frameworks by examining multi-level risk contexts for HIV infection and situating individual HIV infection risks within wider network, community, and public policy contexts as well as epidemic stage. The utility of the MSEM is demonstrated with case studies of HIV risk among PID and MSM. The MSEM is a flexible model for guiding epidemiologic studies among key populations at risk for HIV in diverse sociocultural contexts. Successful HIV prevention strategies for key populations require effective integration of evidence-based biomedical, behavioral, and structural interventions. While the focus of epidemiologic studies has traditionally been on

  17. A study to modify, extend, and verify, an existing model of interactive-constructivist school science teaching

    Science.gov (United States)

    Numedahl, Paul Joseph

    The purpose of this study was to gain an understanding of the effects an interactive-constructive teaching and learning approach, the use of children's literature in science teaching and parental involvement in elementary school science had on student achievement in and attitudes toward science. The study was done in the context of Science PALS, a professional development program for inservice teachers. An existing model for interactive-constructive elementary science was modified to include five model variables; student achievement, student attitudes, teacher perceptions, teacher performance, and student perceptions. Data were collected from a sample of 12 teachers and 260 third and fourth grade students. Data analysis included two components, (1) the examination of relationships between teacher performance, teacher perceptions, student achievement and attitudes, and (2) the verification of a model using path analysis. Results showed a significant correlation between teacher perceptions and student attitude. However, only one model path was significant; thus, the model could not be verified. Further examination of the significant model path was completed. Study findings included: (1) Constructivist notions of teaching and learning may cause changes in the traditional role relationship between teachers and students leading to negative student attitudes. (2) Children who perceive parental interest toward science education are likely to have a positive attitude toward science learning, increased self-confidence in science and possess accurate ideas concerning the nature of science. (3) Students who perceive science instruction as relevant are likely to possess a positive attitude toward science learning, increased self-confidence in science, and possess accurate ideas concerning the nature of science. (4) Students who perceive their classroom as aligning with constructivist principles are likely to possess a positive attitude toward science, an increased self

  18. 3D elastic wave modeling using modified high‐order time stepping schemes with improved stability conditions

    KAUST Repository

    Chu, Chunlei; Stoffa, Paul L.; Seif, Roustam

    2009-01-01

    We present two Lax‐Wendroff type high‐order time stepping schemes and apply them to solving the 3D elastic wave equation. The proposed schemes have the same format as the Taylor series expansion based schemes, only with modified temporal extrapolation coefficients. We demonstrate by both theoretical analysis and numerical examples that the modified schemes significantly improve the stability conditions.

  19. Modeling the Population Health Impact of Introducing a Modified Risk Tobacco Product into the U.S. Market

    Directory of Open Access Journals (Sweden)

    Smilja Djurdjevic

    2018-05-01

    Full Text Available Philip Morris International (PMI has developed the Population Health Impact Model (PHIM to quantify, in the absence of epidemiological data, the effects of marketing a candidate modified risk tobacco product (cMRTP on the public health of a whole population. Various simulations were performed to understand the harm reduction impact on the U.S. population over a 20-year period under various scenarios. The overall reduction in smoking attributable deaths (SAD over the 20-year period was estimated as 934,947 if smoking completely went away and between 516,944 and 780,433 if cMRTP use completely replaces smoking. The reduction in SADs was estimated as 172,458 for the World Health Organization (WHO 2025 Target and between 70,274 and 90,155 for the gradual cMRTP uptake. Combining the scenarios (WHO 2025 Target and cMRTP uptake, the reductions were between 256,453 and 268,796, depending on the cMRTP relative exposure. These results show how a cMRTP can reduce overall population harm additionally to existing tobacco control efforts.

  20. Cross-Cultural Validation of the Modified Practice Attitudes Scale: Initial Factor Analysis and a New Factor Model.

    Science.gov (United States)

    Park, Heehoon; Ebesutani, Chad K; Chung, Kyong-Mee; Stanick, Cameo

    2018-01-01

    The objective of this study was to create the Korean version of the Modified Practice Attitudes Scale (K-MPAS) to measure clinicians' attitudes toward evidence-based treatments (EBTs) in the Korean mental health system. Using 189 U.S. therapists and 283 members from the Korean mental health system, we examined the reliability and validity of the MPAS scores. We also conducted the first exploratory and confirmatory factor analysis on the MPAS and compared EBT attitudes across U.S. and Korean therapists. Results revealed that the inclusion of both "reversed-worded" and "non-reversed-worded" items introduced significant method effects that compromised the integrity of the one-factor MPAS model. Problems with the one-factor structure were resolved by eliminating the "non-reversed-worded" items. Reliability and validity were adequate among both Korean and U.S. therapists. Korean therapists also reported significantly more negative attitudes toward EBTs on the MPAS than U.S. therapists. The K-MPAS is the first questionnaire designed to measure Korean service providers' attitudes toward EBTs to help advance the dissemination of EBTs in Korea. The current study also demonstrated the negative impacts that can be introduced by incorporating oppositely worded items into a scale, particularly with respect to factor structure and detecting significant group differences.