5,188 research outputs found
Problems on electrorheological fluid flows
We develop a model of an electrorheological fluid such that the fluid is
considered as an anisotropic one with the viscosity depending on the second
invariant of the rate of strain tensor, on the module of the vector of electric
field strength, and on the angle between the vectors of velocity and electric
field. We study general problems on the flow of such fluids at nonhomogeneous
mixed boundary conditions, wherein values of velocities and surface forces are
given on different parts of the boundary. We consider the cases where the
viscosity function is continuous and singular, equal to infinity, when the
second invariant of the rate of strain tensor is equal to zero. In the second
case the problem is reduced to a variational inequality. By using the methods
of a fixed point, monotonicity, and compactness, we prove existence results for
the problems under consideration. Some efficient methods for numerical solution
of the problems are examined.Comment: Presented to the journal "Discrete and Continuous Dynamical Systems,
Series
THE STRUCTURE, PERFORMANCE, AND SUSTAINABILITY OF AGRICULTURE IN THE MOUNTAIN REGION
Farmers in the Mountain Region-in both metro and nonmetro areas-face growth in population and nonfarm employment that affects land use and how farmers operate their businesses. Even in remote locations, people moving to amenity areas may result in farmers changing their operations. Sustainable agriculture, already practiced by Mountain Region farmers to some extent, may help farming to continue. Nonfarm people also have an interest in the continuation of agriculture and the adaptation of sustainable practices, in order to help preserve the amenities that make the region attractive to migrants. Growth in the region does provide some benefits to farmers, however. Growth can help keep the value of farmland up through nonfarm demand for land. In addition, the greater availability of jobs means that off-farm work is available to households operating farms. Off-farm work is particularly important, given the concentrated distribution of farm income.Production Economics,
A dynamical symmetry for supermembranes
A dynamical symmetry for supersymmetric extended objects is given.Comment: 3 page
Literatuurverslag duurzame bouwprocessen.
De Vastgoedgroep Drienerlo (VGD) heeft het CSTM opdracht gegeven een literatuurstudie uit te voeren naar duurzame bouwprocessen. De opdracht betrof het uitzoeken wat er in de wetenschappelijke literatuur bekend is over duurzame bouwprocessen. Daarbij gaat het niet om de duurzaamheidgraad van de gebouwen in opgeleverde fase, maar de duurzaamheidgraad van bouwen renovatieprocessen. Omdat het gaat om de integrale duurzaamheidsgraad van de processen wordt in tegenstelling tot andere studies niet alleen stilgestaan bij gebruik van (duurzame) energie, maar is ook naar andere duurzaamheidaspecten gekeken
A C0 interior penalty discontinuous galerkin method and an equilibrated a posteriori error estimator for a nonlinear fourth order elliptic boundary value problem of p-biharmonic type
We consider a C Interior Penalty Discontinuous Galerkin (C0IPDG) approximation of a nonlinear fourth order elliptic boundary value problem of p-harmonic type and an equilibrated a posteriori error estimator. The C0IPDG method can be derived from a discretization of the corresponding minimization problem involving a suitably defined reconstruction operator. The equilibrated a posteriori error estimator provides an upper bound for the discretization error in the broken norm in terms of the associated primal and dual energy functionals. It requires the construction of an equilibrated flux and an equilibrated moment tensor based on a three-field formulation of the C0IPDG approximation. The relationship with a residual-type a posteriori error estimated is studied as well. Numerical results illustrate the performance of the suggested approach
A Super-Integrable Discretization of the Calogero Model
A time-discretization that preserves the super-integrability of the Calogero
model is obtained by application of the integrable time-discretization of the
harmonic oscillator to the projection method for the Calogero model with
continuous time. In particular, the difference equations of motion, which
provide an explicit scheme for time-integration, are explicitly presented for
the two-body case. Numerical results exhibit that the scheme conserves all
the conserved quantities of the (two-body) Calogero model with a
precision of the machine epsilon times the number of iterations.Comment: 22 pages, 5 figures. Added references. Corrected typo
Relative Age Effect in Elite German Soccer: Influence of Gender and Competition Level
The relative age effect (RAE) is associated with (dis)advantages in competitive sports.
While the RAE in elite male soccer reveals a skewed birthdate distribution in relation to a
certain cut-off date, research of RAE in elite female soccer is affected by small number
of samples and conflicting results. The purpose of this study was to investigate the
RAE in elite adult German soccer regarding gender and competition level. The sample
comprised 680 female and 1,083 male players of the two top German leagues during
the 2019/20 season and German national teams (A-Team to Under 19). Differences
between the observed and expected birthdate distributions were analyzed using chisquare
statistics and effect sizes followed by calculating odds ratios. Results showed
a statistically significant RAE with small effect size across all players included for both
genders (female players: P < 0.001, W = 0.16, male players: P < 0.001, W = 0.23). The
identified RAE was based on an over-representation of players born at the beginning of
the year. According to gender and competition level, RAEs were more pronounced in
German male soccer. While significant RAEs were found among males in the first two
leagues (first league: P < 0.001, W = 0.19, second league: P < 0.001, W = 0.26), the
RAE of females was more pronounced in the second league (first league: P = 0.080,
W = 0.16, second league: P = 0.002, W = 0.20). The analysis of RAE regarding the
national teams revealed a statistically significant RAE with large effect size for only the
youngest investigated age group of male players (Under 19: P = 0.022, W = 0.52).
Our data show an RAE in female and male German adult soccer, which could be
accompanied by a loss of valuable elite players during the youth phase of the career.
Consequently, the pool of talented players at the adult level would be limited
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