Let Sn be the n-sphere of constant positive curvature. For n ≥ 2, we will show that a measure on the unit tangent bundle of S, which is even and invariant under the geodesic flow, is not uniquely determined by its projection to S. Mathematics Subject Classification (2000). 53D25.

We investigate the distribution of orbits of a non-elementary discrete hyperbolic subgroup Γ acting on Hn and its geometric boundary ∂∞(H). In particular, we show that if Γ admits a finite Bowen-Margulis-Sullivan measure (for instance, if Γ is geometrically finite), then every Γ-orbit in ∂∞(H) is equidistributed with respect to the Patterson-Sullivan measure supported on the limit set Λ(Γ). The...

In this paper, a structure of patch antenna operating at 0.5 GHz is proposed for ground-penetrating radar (GPR) applications, with an optimized performance low frequencies. The was designed using FR4 substrate, 4.4 permittivity value, and tangent loss equivalent to 0.021. prototype design backed by rectangular reflector, which has improved the gain directivity. evaluated in terms return loss, g...

This research proposed microstrip circular patch antenna simulation at a working frequency 3500 MHz. The has been designed using Duroid RT5880 substrate with dielectric constant (εr) = 2.2, thickness (h) 1.575 mm, and tangent loss 0.0009 line feeding. result, return value obtained -26.385, VSWR 1.09, gain 7.64 dBi, total radiation efficiency -0.6489 dB, bandwidth 72 MHz (3468.8 – 3541.9 MHz).

A tangent manifold is a pair (M, J) with J a tangent structure (J2 = 0, ker J = im J) on the manifold M . A systematic study of tangent manifolds was done by I. Vaisman in [5]. One denotes by HM any complement of im J := TV . Using the projections h and v on the two terms in the decomposition TM = HM ⊕TV one naturally defines an almost complex structure F on M . Adding to the pair (M, J) a Riem...

We have developed a new technique for accurate measurement of the loss of superconducting microstrips at mm-wave frequencies. In this technique, we optically couple power to slot antenna, which is connected to one port of a hybrid coupler. One of the output ports of the hybrid delivers power to a series of mm-wave microstrip resonators which are capacitively coupled to a feedline followed by an...

There is a canonical exact symplectic structure on the unit tangent bundle of a Riemannian manifold M given by pulling-back the symplectic two form ω and Liouville one form λ from the cotangent bundle T ∗M using the Riemannian metric. The pull-back of λ gives a contact form on level-sets of the length function on TM . The geodesic flow of M is given by the Reeb vectorfield of this contact struc...

Which smooth compact 4-manifolds admit an Einstein metric with non-negative Einstein constant? A complete answer is provided in the special case of 4-manifolds that also happen to admit either a complex structure or a symplectic structure. A Riemannian manifold (M, g) is said to be Einstein if it has constant Ricci curvature, in the sense that the function v −→ r(v, v) on the unit tangent bundl...

In order to investigate the impact of microstructures and deformation mechanisms on the ductility of materials, the criterion first proposed by Rice is applied to elastic-plastic tangent moduli derived from a large strain micromechanical model combined with a self-consistent scale transition technique. This approach takes into account several microstructural aspects for polycrystalline aggregat...

INTRODUCTION: The viscoelastic behavior of articular cartilage is derived from complex interactions involving the fluid and the extracellular matrix (ECM) of proteoglycans (PG) and collagen fibrils. Enzymatic digestion of the ECM components makes it possible to study specific structure-function relationships of articular cartilage. To some extent, enzymatic treatment also simulates the patholog...