scholarly journals Simulation of Capillary Pressure Overshoot in Snow Combining Trapping of the Wetting Phase With a Nonequilibrium Richards Equation Model

2019 ◽  
Vol 55 (1) ◽  
pp. 236-248 ◽  
Author(s):  
Nicolas R. Leroux ◽  
John W. Pomeroy
Keyword(s):  
Capillary Pressure ◽  
Equation Model ◽  
Richards Equation ◽  
Pressure Overshoot

Richards Equation Model of a Rain Garden

2004 ◽  
Vol 9 (3) ◽  
pp. 219-225 ◽  
Author(s):  
Alejandro R. Dussaillant ◽  
Chin H. Wu ◽  
Kenneth W. Potter
Keyword(s):  
Equation Model ◽  
Richards Equation ◽  
Rain Garden

Domain decomposition adaptivity for the Richards equation model

Computing ◽  
2013 ◽  
Vol 95 (S1) ◽  
pp. 501-519 ◽  
Author(s):  
Michal Kuraz ◽  
Petr Mayer ◽  
Vojtech Havlicek ◽  
Pavel Pech
Keyword(s):  
Domain Decomposition ◽  
Equation Model ◽  
Richards Equation

scholarly journals Two-phase flow equations with a dynamic capillary pressure

2012 ◽  
Vol 24 (1) ◽  
pp. 49-75 ◽  
Author(s):  
JAN KOCH ◽  
ANDREAS RÄTZ ◽  
BEN SCHWEIZER
Keyword(s):  
Capillary Pressure ◽  
Two Phase Flow ◽  
Immiscible Fluids ◽  
Richards Equation ◽  
Phase Flow ◽  
Two Phase ◽  
Compactness Result ◽  
Flow Equations ◽  
Two Phases ◽  
Capillary Pressure Curves

We investigate the motion of two immiscible fluids in a porous medium described by a two-phase flow system. In the capillary pressure relation, we include static and dynamic hysteresis. The model is well established in the context of the Richards equation, which is obtained by assuming a constant pressure for one of the two phases. We derive an existence result for this hysteresis two-phase model for non-degenerate permeability and capillary pressure curves. A discretization scheme is introduced and numerical results for fingering experiments are obtained. The main analytical tool is a compactness result for two variables that are coupled by a hysteresis relation.

scholarly journals Capillary pressure overshoot for unstable wetting fronts is explained by Hoffman's velocity-dependent contact-angle relationship

2014 ◽  
Vol 50 (6) ◽  
pp. 5290-5297 ◽  
Author(s):  
Christine E. Baver ◽  
J.-Yves Parlange ◽  
Cathelijne R. Stoof ◽  
David A. DiCarlo ◽  
Rony Wallach ◽  
...  
Keyword(s):  
Contact Angle ◽  
Capillary Pressure ◽  
Pressure Overshoot

Idiographic Dynamics of Positive Affect in GAD

2020 ◽  
Vol 36 (3) ◽  
pp. 500-509
Author(s):  
Hannah G. Bosley ◽  
Devon B. Sandel ◽  
Aaron J. Fisher
Keyword(s):  
Positive Affect ◽  
Structural Equation ◽  
Alternative Hypothesis ◽  
Equation Model ◽  
Aggregated Data ◽  
Regulatory Strategy ◽  
Constant State ◽  
Automatic Search ◽  
Time Lagged ◽  
Exploratory Procedure

Abstract. Generalized anxiety disorder (GAD) is associated with worry and emotion regulation difficulties. The contrast-avoidance model suggests that individuals with GAD use worry to regulate emotion: by worrying, they maintain a constant state of negative affect (NA), avoiding a feared sudden shift into NA. We tested an extension of this model to positive affect (PA). During a week-long ecological momentary assessment (EMA) period, 96 undergraduates with a GAD analog provided four daily measurements of worry, dampening (i.e., PA suppression), and PA. We hypothesized a time-lagged mediation relationship in which higher worry predicts later dampening, and dampening predicts subsequently lower PA. A lag-2 structural equation model was fit to the group-aggregated data and to each individual time-series to test this hypothesis. Although worry and PA were negatively correlated in 87 participants, our model was not supported at the nomothetic level. However, idiographically, our model was well-fit for about a third (38.5%) of participants. We then used automatic search as an idiographic exploratory procedure to detect other time-lagged relationships between these constructs. While 46 individuals exhibited some cross-lagged relationships, no clear pattern emerged across participants. An alternative hypothesis about the speed of the relationship between variables is discussed using contemporaneous correlations of worry, dampening, and PA. Findings suggest heterogeneity in the function of worry as a regulatory strategy, and the importance of temporal scale for detection of time-lagged effects.

Differential Item Functioning in Brief Instruments of Disordered Eating

2019 ◽  
Vol 35 (6) ◽  
pp. 823-833 ◽  
Author(s):  
Desiree Thielemann ◽  
Felicitas Richter ◽  
Bernd Strauss ◽  
Elmar Braehler ◽  
Uwe Altmann ◽  
...  
Keyword(s):  
Differential Item Functioning ◽  
Disordered Eating ◽  
Structural Equation ◽  
Young Female ◽  
Eating Attitudes ◽  
Equation Model ◽  
German Population ◽  
Test Fairness ◽  
Item Functioning ◽  
Multiple Indicator

Abstract. Most instruments for the assessment of disordered eating were developed and validated in young female samples. However, they are often used in heterogeneous general population samples. Therefore, brief instruments of disordered eating should assess the severity of disordered eating equally well between individuals with different gender, age, body mass index (BMI), and socioeconomic status (SES). Differential item functioning (DIF) of two brief instruments of disordered eating (SCOFF, Eating Attitudes Test [EAT-8]) was modeled in a representative sample of the German population ( N = 2,527) using a multigroup item response theory (IRT) and a multiple-indicator multiple-cause (MIMIC) structural equation model (SEM) approach. No DIF by age was found in both questionnaires. Three items of the EAT-8 showed DIF across gender, indicating that females are more likely to agree than males, given the same severity of disordered eating. One item of the EAT-8 revealed slight DIF by BMI. DIF with respect to the SCOFF seemed to be negligible. Both questionnaires are equally fair across people with different age and SES. The DIF by gender that we found with respect to the EAT-8 as screening instrument may be also reflected in the use of different cutoff values for men and women. In general, both brief instruments assessing disordered eating revealed their strengths and limitations concerning test fairness for different groups.

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