A Solution Set-Based Entropy Principle for Constitutive Modeling in Mechanics

Entropy principles based on thermodynamic consistency requirements are widely used for constitutive modeling in continuum mechanics, providing physical constraints on a priori unknown constitutive functions. The well-known M\"uller-Liu procedure is based on Liu's lemma for linear systems. While the M\"uller-Liu algorithm works well for basic models with simple constitutive dependencies, it cannot take into account nonlinear relationships that exist between higher derivatives of the fields in the cases of more complex constitutive dependencies. The current contribution presents a general solution set-based procedure, which, for a model system of differential equations, respects the geometry of the solution manifold, and yields a set of constraint equations on the unknown constitutive functions, which are necessary and sufficient conditions for the entropy production to stay nonnegative for any solution. Similarly to the M\"uller-Liu procedure, the solution set approach is algorithmic, its output being a set of constraint equations and a residual entropy inequality. The solution set method is applicable to virtually any physical model, allows for arbitrary initially postulated forms of the constitutive dependencies, and does not use artificial constructs like Lagrange multipliers. A Maple implementation makes the solution set method computationally straightforward and useful for the constitutive modeling of complex systems. Several computational examples are considered, in particular, models of gas, anisotropic fluid, and granular flow dynamics. The resulting constitutive function forms are analyzed, and comparisons are provided. It is shown how the solution set entropy principle can yield classification problems, leading to several complementary sets of admissible constitutive functions; such problems have not previously appeared in the constitutive modeling literature

Legehennen in einem mobilen Stallsystem - Auslaufnutzung und Flächenzustand -

The use of the free-range area by laying hens housed in a mobile system and the resulting condition of the range were investigated. The free-range was used very intensively. On an average of nine complete observation days 35 % of the birds (23 – 44 % means per day) were outside the house. The maximum of animals in the free range was 77 %. 75 % (60 – 95 %) of the hens outside the house stayed in an area of 20 m around the house. This led to deteriorated conditions of the range in these areas. By moving the mobile house regularly (after 2 weeks in summer and 6 weeks in winter) a destruction of the vegetation could be avoided, while after not moving the house for three months in winter a complementary seeding became necessary. We conclude that the use of mobile systems for poultry in conjunction with a regular change of position and sufficient area per animal can avoid destruction of the vegetation despite an intensive use of the free-range all year round

Legehennen in einem mobilen Stallsystem - Flächenmanagement und resultierende Stickstoffgehalte im Auslauf -

In the last years free range poultry was often criticised for its negative impacts on environment. As the animals do not use the run equally, a big part of the excreted nutrients are accumulated in the area close to the poultry house. This can lead to an increased rate of nutrient loss especially nitrogen by leaching. Within this study the use of a mobile housing system for 1.000 layers on an organic farm in North Hessia with a mean of 700 mm precipitation per year and an average of 8,9°C (soil texture: loam in the first, silt loam in the second year) was observed for two years. A documentation and optimization of the management and regular investigations into the contents of mineral nitrogen in all parts of the outdoor run were carried out. The aim of the study was to survey, if a well-balanced distribution of nutrients can be reached by moving the house within the free-range and which management is necessary for that. The results showed a better distribution of mineral nitrogen in the second year, when the house was moved in winter time every six weeks, while the contents were slightly less well-balanced, when it stayed at one position for three months in the first winter . In both years the highest amounts of mineral nitrogen in any part of the hen run with 37 and 24 mg / kg DM were much lower than the contents of up to 160 mg / kg DM close to stationary houses examined in other studies. The results of this study show that a well-balanced distribution of nutrients in free-ranges for poultry can be reached by using mobile housing systems combined with the right management

Samenfeste Sorten oder Hybriden - Untersuchungen an Speisemöhren aus einem Anbauvergleich an zwei Standorten des Ökologischen Landbaus

An zwei Standorten des Ökologischen Landbaus (Neu-Eichenberg, Nordhessen: mittlerer bis schwerer Boden; Queck, Osthessen: leichter Boden) wurden Feldversuche mit Möhren durchgeführt, um sechs samenfeste Sorten und sechs Hybriden auf ihre Anbautauglichkeit zu prüfen. Außer der Roh- und Handelswarenerträge wurden die Einheitlichkeit des Erntegutes (cv%) bestimmt und die Gehalte an Mineralstoffen (K, Ca, P, Mg) und Zuckern (D-Glucose, D-Fructose, Saccharose) analysiert. Auch sogenannte Bildschaffende Methoden (Kupferchloridkristallisation, Steigbild, Rundfilterchromatogramm) kamen zur Anwendung. Die untersuchten Hybriden erzielten Mehrerträge von 25 bis 29% und in den meisten Fällen auch gleichmäßiger lange Rüben als die Samenfesten. Die Inhaltsstoffuntersuchungen zeigten höhere Mineralstoffgehalte und niedrigere Quotienten von Mono- zu Disaccharide bei den samenfesten Sorten. Mithilfe der Bildschaffenden Methoden konnten die Proben blind klar in zwei unterschiedliche Gruppen differenziert werden: Die Bilder der samenfesten Sorten waren im Vergleich zu denjenigen der Hybriden geprägt durch einen höheren Grad an Formintensität und Reife

SGARFACE: A Novel Detector For Microsecond Gamma Ray Bursts

The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at the Whipple Observatory utilizing the Whipple 10m gamma-ray telescope. SGARFACE is sensitive to gamma-ray bursts of more than 100MeV with durations from 100ns to 35us and provides a fluence sensitivity as low as 0.8 gamma-rays per m^2 above 200MeV (0.05 gamma-rays per m^2 above 2GeV) and allows to record the burst time structure.Comment: 29 pages, 14 figures, accepted for publication in Astroparticle Physic

Samenfeste Sorten oder Hybriden - Anbauvergleich von Möhren unter den Verhältnissen des Ökologischen Landbaus

A field trial with carrots was carried out in 1998 at two sites in Hesse (North: loamy soil in Neu-Eichenberg; East: sandy soil in Queck) to compare 6 open pollinating and 6 F1 hybrids under an Organic Farming regime. Characteristics of cultivation, harvest, quality, and longevity were measured. Of the parameters of cultivation and harvest the hybrids showed a more intensive foliage growth, higher marketable yields (plus 29 and 25%), and more homogeneous taproots than the open pollinating cultivars. Picture forming methods clearly separated the samples into the two groups of breeding methods. The open pollinating cultivars were characterized by higher degrees of form intensity and ripeness and a stable vitality. The hybrids of the sandy site had a better keeping quality after 6½ months storage, only the open pollinating cultivar ‘Rodelika’ had a very high ranking similar to the hybrids ‘Kardame F1’ and ‘Bolero F1’

Constituent Quarks, Diquarks and the N-Delta Mass Splitting

We analyze hadron as well as quark and diquark correlation functions in Landau gauge in order to extract information on the spin dependence of the quark-quark interaction. We find evidence that the N-Delta mass splitting can be attributed to the spin dependence of the interaction between quarks in a colour anti-triplet state with spin 0 and 1, respectively. The lightest excitations are observed in the S=0 channel. However, no evidence for a deeply bound diquark state is found.Comment: LATTICE98(spectrum), 3 pages, LaTeX2e File, 4 EPS-figures, espcrc2.st

Simulation of the Flow and Acoustic Field of a Fan

The focus of the present work is the steady and unsteady numerical simulation of flow field and flow-induced acoustic field of a fan using a hybrid approach. The steady simulation of the flow field is carried out with a realizable k-epsilon turbulence model. In a second step the result are used for the evaluation of the acoustic sources, which are used as input data of the Broadband Noise Model. From this computational acoustics (CA) we get a qualitative map of acoustic power level in the entire computational domain. From steady flow fields with different mass flows as inlet boundary condition the characteristic curve of the fan (pressure vs. mass flow) is evaluated. In the unsteady simulation, the acoustic noise propagation is computed using the Ffowcs Williams and Hawkings (FW-H) analogy. The source term in the acoustic propagation equation is achieved from the CFD result. With this unsteady simulation the transient acoustic power level in every location can be calculated, which enables a FFT-analysis of the acoustic field