EFFICIENCY MEASURES USING THE RAY-HOMOTHETIC FUNCTION: A MULTIPERIOD ANALYSIS

Recent investigations have provided mixed assessments of farm firm efficiency. This analysis examined the efficiency of a homogeneous sample of central Illinois grain farms over a six-year period. A best-practice frontier was constructed using the ray-homothetic function, which allowed optimal farm output to vary with factor intensity. Efficiency measures were found to increase with temporal aggregation. The ray-homothetic approach was found to attribute high scale inefficiencies to larger sample farms in cases where the factor shares did not vary appreciably across farms. The findings suggest that policy recommendations regarding farm efficiency must be made with care.Agribusiness,

Band gaps in the relaxed linear micromorphic continuum

In this note we show that the relaxed linear micromorphic model recently proposed by the authors can be suitably used to describe the presence of band-gaps in metamaterials with microstructures in which strong contrasts of the mechanical properties are present (e.g. phononic crystals and lattice structures). This relaxed micromorphic model only has 6 constitutive parameters instead of 18 parameters needed in Mindlin- and Eringen-type classical micromorphic models. We show that the onset of band-gaps is related to a unique constitutive parameter, the Cosserat couple modulus $\mu_{c}$ which starts to account for band-gaps when reaching a suitable threshold value. The limited number of parameters of our model, as well as the specific effect of some of them on wave propagation can be seen as an important step towards indirect measurement campaigns

Survey of the Vegetation and Flora of a Wetland in Kiser Lake State Park, Champaign County, Ohio

Author Institution: Department of Botany, Miami UniversityWe classified plant communities by criteria of physiognomy, environment, and flora. Use of Mueller-Dombois and Ellenberg's classification scheme for the world's vegetation provided 6 vegetation categories. The results of a Bray-Curtis ordination were consistent with our field observation of a correlation between these vegetation categories and a soil moisture gradient. The results of a cluster analysis were consistent with 5 of the vegetation categories, but the sixth should be subdivided according to variations in floristic composition. Our proposed classification has 8 plant communities: an alluvial forest dominated by Acer negundo and Parthenocissus quinquefolia, a reed swamp dominated by Eupatorium perfoliatum and Typha latifolia, a deciduous thicket dominated by Crataegus punctata, a second deciduous thicket dominated by Cornus obliqua and Aster pilosus, and a third deciduous thicket dominated by Rosa palustris and R. setigera, a perennial forb community dominated by Clematis virginiana and Verbesina alternifolia, a tall-sedge swamp dominated by Carex stricta and Eupatorium maculatum, and a herbaceous floating meadow dominated by Typha latifolia and Eupatorium perfoliatum. We list 183 species (of 61 families) and state the communities in which each is common

Doppler imaging of AR Lacertae at three epochs

Observations from IUE were used to study the structure of the lower chromosphere of AR Lacertae in the light of Mg II k. Sequences of LWR/P-HI images distributed around the binary period at three epochs were obtained. Discrete plage-like regions of enhanced Mg II surface flux in this system are identified. There are temporal variations in the Mg II flux on timescales of hours as well as substantial changes in chromospheric morphology on timescales of years. Even with the limited S/N attainable with the IUE, one can map the gross structures of active stellar atmospheres. With such information, one can begin to study the true 3-D structure of the atmospheres of late-type stars

A note on non-homogeneous deformations with homogeneous Cauchy stress for a strictly rank-one convex energy in isotropic hyperelasticity

It has recently been shown that for a Cauchy stress response induced by a strictly rank-one convex hyperelastic energy potential, a homogeneous Cauchy stress tensor field cannot correspond to a non-homogeneous deformation if the deformation gradient has discrete values, i.e. if the deformation is piecewise affine linear and satisfies the Hadamard jump condition. In this note, we expand upon these results and show that they do not hold for arbitrary deformations by explicitly giving an example of a strictly rank-one convex energy and a non-homogeneous deformation such that the induced Cauchy stress tensor is constant. In the planar case, our example is related to another previous result concerning criteria for generalized convexity properties of conformally invariant energy functions, which we extend to the case of strict rank-one convexity

Evaluation of ozone difluoride as a liquid propellant additive Final report

Ozone difluoride evaluated as liquid propellant additiv

Hyperelastic bodies under homogeneous Cauchy stress induced by non-homogeneous finite deformations

We discuss whether homogeneous Cauchy stress implies homogeneous strain in isotropic nonlinear elasticity. While for linear elasticity the positive answer is clear, we exhibit, through detailed calculations, an example with inhomogeneous continuous deformation but constant Cauchy stress. The example is derived from a non rank-one convex elastic energy

Supply assurance in the nuclear fuel cycle

Errata sheet inserted.The economic, technical and political issues which bear on the security of nuclear fuel supply internationally are addressed. The structure of international markets for nuclear fuel is delineated; this includes an analysis of the political constraints on fuel availability, especially the connection to supplier nonproliferation policies. The historical development of nuclear fuel assurance problems is explored and an assessment is made of future trends in supply and demand and in the political context in which fuel trade will take place in the future. Finally, key events and policies which will affect future assurance are identified.U.S. Dept. of Energy Contract no. 426365-S