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Optimized Multimode Interference Fiber Based Refractometer in A Reflective Interrogation Scheme
A fiber based refractometer in a reflective interrogation scheme is investigated and optimized. A thin gold film was deposited on the tip of a coreless fiber section, which is spliced with a single mode fiber. The coreless fiber is a multimode waveguide, and the observed effects are due to multimode interference. To investigate and optimize the structure, the multimode part of the sensor is built with 3 different lengths: 58 mm, 29 mm and 17 mm. We use a broadband light source ranging from 1475 nm to 1650 nm and we test the sensors with liquids of varying refractive indices, from 1.333 to 1.438. Our results show that for a fixed wavelength, the sensor sensitivity is independent of the multimode fiber length, but we observed a sensitivity increase of approximately 0.7 nm/RIU for a one-nanometer increase in wavelength
Unitarity of the Leptonic Mixing Matrix
We determine the elements of the leptonic mixing matrix, without assuming
unitarity, combining data from neutrino oscillation experiments and weak
decays. To that end, we first develop a formalism for studying neutrino
oscillations in vacuum and matter when the leptonic mixing matrix is not
unitary. To be conservative, only three light neutrino species are considered,
whose propagation is generically affected by non-unitary effects. Precision
improvements within future facilities are discussed as well.Comment: Standard Model radiative corrections to the invisible Z width
included. Some numerical results modified at the percent level. Updated with
latest bounds on the rare tau decay. Physical conculsions unchange
Entangled single-wire NiTi material: a porous metal with tunable superelastic and shape memory properties
NiTi porous materials with unprecedented superelasticity and shape memory
were manufactured by self-entangling, compacting and heat treating NiTi wires.
The versatile processing route used here allows to produce entanglements of
either superelastic or ferroelastic wires with tunable mesostructures. Three
dimensional (3D) X-ray microtomography shows that the entanglement
mesostructure is homogeneous and isotropic. The thermomechanical compressive
behavior of the entanglements was studied using optical measurements of the
local strain field. At all relative densities investigated here ( 25 -
40), entanglements with superelastic wires exhibit remarkable macroscale
superelasticity, even after compressions up to 25, large damping capacity,
discrete memory effect and weak strain-rate and temperature dependencies.
Entanglements with ferroelastic wires resemble standard elastoplastic fibrous
systems with pronounced residual strain after unloading. However, a full
recovery is obtained by heating the samples, demonstrating a large shape memory
effect at least up to 16% strain.Comment: 31 pages, 10 figures, submitted to Acta Materiali
Analytical Results for the Statistical Distribution Related to Memoryless Deterministic Tourist Walk: Dimensionality Effect and Mean Field Models
Consider a medium characterized by N points whose coordinates are randomly
generated by a uniform distribution along the edges of a unitary d-dimensional
hypercube. A walker leaves from each point of this disordered medium and moves
according to the deterministic rule to go to the nearest point which has not
been visited in the preceding \mu steps (deterministic tourist walk). Each
trajectory generated by this dynamics has an initial non-periodic part of t
steps (transient) and a final periodic part of p steps (attractor). The
neighborhood rank probabilities are parameterized by the normalized incomplete
beta function I_d = I_{1/4}[1/2,(d+1)/2]. The joint distribution
S_{\mu,d}^{(N)}(t,p) is relevant, and the marginal distributions previously
studied are particular cases. We show that, for the memory-less deterministic
tourist walk in the euclidean space, this distribution is:
S_{1,d}^{(\infty)}(t,p) = [\Gamma(1+I_d^{-1})
(t+I_d^{-1})/\Gamma(t+p+I_d^{-1})] \delta_{p,2}, where t=0,1,2,...,\infty,
\Gamma(z) is the gamma function and \delta_{i,j} is the Kronecker's delta. The
mean field models are random link model, which corresponds to d \to \infty, and
random map model which, even for \mu = 0, presents non-trivial cycle
distribution [S_{0,rm}^{(N)}(p) \propto p^{-1}]: S_{0,rm}^{(N)}(t,p) =
\Gamma(N)/\{\Gamma[N+1-(t+p)]N^{t+p}\}. The fundamental quantities are the
number of explored points n_e=t+p and I_d. Although the obtained distributions
are simple, they do not follow straightforwardly and they have been validated
by numerical experiments.Comment: 9 pages and 4 figure
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