Search results for "SIP"

Frequency dependence of the microwave surface resistance of MgB2 by coaxial cavity resonator

2014

Abstract We report on the microwave (mw) properties of a cylindrical MgB2 rod prepared by the reactive liquid Mg infiltration technology. The MgB2 rod, 94.3 mm long, is used as inner conductor of a coaxial cavity having a Cu tube as external conductor. By analyzing the resonance curves of the cavity in the different resonant modes and at different temperatures, we have determined the temperature dependence of the mw surface resistance, R s , of the MgB2 material, at fixed frequencies, and the frequency dependence of R s , at fixed temperatures. Our results show that the R s ( f ) curves follow a f n law, where n decreases on increasing the temperature, starting from n ≈ 2 , at T = 4.2 K , d…

Anisotropic flow in striped superhydrophobic channels

2012

We report results of dissipative particle dynamics simulations and develop a semi-analytical theory of an anisotropic flow in a parallel-plate channel with two superhydrophobic striped walls. Our approach is valid for any local slip at the gas sectors and an arbitrary distance between the plates, ranging from a thick to a thin channel. It allows us to optimize area fractions, slip lengths, channel thickness and texture orientation to maximize a transverse flow. Our results may be useful for extracting effective slip tensors from global measurements, such as the permeability of a channel, in experiments or simulations, and may also find applications in passive microfluidic mixing.

First and second viscosity measurements in superfluid 3He-B

1996

By means of diaphragm-driven flow experiments in 3He-B in a thin slab geometry, we have measured the first and second viscosities, η and 3 at pressures of 0, 5, 10 and 29.3 bar. Our measurement of 3 has better established theoretical foundations than previous measurements and also extends to higher pressures. 3 and η were deduced from the frequency dependence of the flow dissipation determined from bandwidth measurements for several normal modes of the diaphragm; a first order slip correction was used in the determination of η. Near Tc, 3 α (1 - T/Tc)-1/2 in accordance with theoretical predictions but below T/Tc ~ 0.6 we observe a rapid drop in 3 signifying a departure from the hydrodynamic…

Effective slippage on superhydrophobic trapezoidal grooves

2013

We study the effective slippage on superhydrophobic grooves with trapezoidal cross-sections of various geometries (including the limiting cases of triangles and rectangular stripes), by using two complementary approaches. First, dissipative particle dynamics (DPD) simulations of a flow past such surfaces have been performed to validate an expression [E.S.Asmolov and O.I.Vinogradova, J. Fluid Mech. \textbf{706}, 108 (2012)] that relates the eigenvalues of the effective slip-length tensor for one-dimensional textures. Second, we propose theoretical estimates for the effective slip length and calculate it numerically by solving the Stokes equation based on a collocation method. The comparison …

A Composite Phononic Crystal Design for Quasiparticle Lifetime Enhancement in Kinetic Inductance Detectors

2019

A nanoscale phononic crystal filter (reflector) is designed for a kinetic inductance detector where the reflection band is matched to the quasiparticle recombination phonons with the aim to increase quasiparticle lifetime in the superconducting resonator. The inductor is enclosed by a 1 um wide phononic crystal membrane section with two simple hole patterns that each contain a partial spectral gap for various high frequency phonon modes. The phononic crystal is narrow enough for low frequency thermal phonons to propagate unimpeded. With 3D phonon scattering simulations over a 40 dB attenuation in transmitted power is found for the crystal, which was previously estimated to give a lifetime e…

Controlling Janus Nanodisc Topology through ABC Triblock Terpolymer/Homopolymer Blending in 3D Confinement

2021

Janus particles have drawn considerable interest as colloidal surfactants, microswimmers, and building blocks for colloidal lattices. So far, research primarily focused on spherical Janus particles for which a number of fabrication methods are well established. Janus particles with geometric anisotropy offer shape-dependent properties in addition to surface anisotropy, but their synthesis is more challenging. Here, we report a variety of polymeric Janus nanoparticles synthesized from ABC triblock terpolymer microphases in microemulsion droplets. Evaporation-induced assembly of the ABC triblock terpolymers led to prolate microparticles with A/C lamellae stacked along the particle’s major axi…

Frequency-Dependent Dielectric Polarizability of Flexible Polyelectrolytes in Electrolyte Solution: A Dissipative Particle Dynamics Simulation

2019

Multi-scale analysis to determine fibre/matrix debonding criteria in SiCTitanium composites with and without consideration of the manufacturing resid…

1998

Abstract Certain dissipative phenomena in long-fibre composites are still quite poorly understood, especially the debonding between the fibre and the matrix. The present study is an attempt to elucidate this phenomenon in SiC Titanium metal-matrix composites. The phenomenon is analysed both experimentally and numerically, both on the scale of the constituents and on the scale of the equivalent homogeneous material. This leads to the identification of a local debonding criterion which helps to determine a global debonding criterion. This approach is made for two cases, without and without consideration of the manufacturing residual stresses.

Momentum and energy dissipation of hot electrons in a Pb/Ag(111) quantum well system

2021

The band structure of multilayer systems plays a crucial role for the ultrafast hot carrier dynamics at interfaces. Here, we study the energy- and momentum-dependent quasiparticle lifetimes of excited electrons in a highly ordered Pb monolayer film on Ag(111) prior and after the adsorption of a monolayer of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA). Using time-resolved two-photon momentum microscopy with femtosecond visible light pulses, we show that the electron dynamics of the Pb/Ag(111) quantum well system is largely dominated by two types of scattering processes: (i) isotropic intraband scattering processes within the quantum well state (QWS) and (ii) isotropic interband sca…

Theoretical and experimental developments in quantum spin liquid in geometrically frustrated magnets: a review

2019

The exotic substances have exotic properties. One class of such substances is geometrically frustrated magnets, where correlated spins reside in the sites of triangular or kagome lattice. In some cases, such magnet would not have long-range magnetic order. Rather, its spins tend to form kind of pairs, called valence bonds. At $$T \rightarrow 0$$ these highly entangled quantum objects condense in the form of a liquid, called quantum spin liquid (QSL). The observation of a gapless QSL in actual materials is of fundamental significance both theoretically and technologically, as it could open a path to creation of topologically protected states for quantum information processing and computation…