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Abstract

Inflatable and other membrane structures are expected to become increasingly important in space exploration due to their light weight and low cost. Unlike rigid structures, these structures are typically fabricated of flexible polymers and require internal pressurization to achieve structural integrity. Due to this, inflatable structures are vulnerable to the harsh space environment and catastrophic failure from structural vibration. A MEMS-based health monitoring and control system (HMCS) for space inflatables has been developed at the University of Arkansas. Fabricated mostly from polymeric materials, the HMCS is lightweight, flexible and can be attached directly to the external surface of an inflatable to provide health monitoring. Structure-wise, the HMCS is a three-dimensional multichip module with a sensor layer at the top, a common polyimide substrate in the middle and an actuator layer at the bottom. The sensor layer consists of an interconnected network of MEMS sensors for monitoring the environmental conditions around the inflatable and also the structural vibration of the inflatable. The actuator layer, fabricated from electroactive polymers, provides a two-dimensional shape control capability to the HMCS. When operated with strain and vibration sensors in the sensor layer, the polymer actuator can deform the surface contour of the inflatable to remove 'wrinkles' and dampen structural vibration.

Boundary conditions in Ginsburg–Landau theory and critical temperature of high- superconductors

“…Taking into account that the critical temperature of the bulk niobium (9.46 K) is significantly higher than T * c (10), the critical temperature of a hypothetical bulk superconductor consisting only of CuO 2 layers should be higher than the maximum critical temperature achieved at present in the cuprate superconductors. Observed decrease in T * c (n) for n > 3 is due, as usual [5], the low level of doping in the cuprate layers in this case. Note the T c = 155 K is not the maximum critical temperature of the cuprate superconductors.…”

“…The pseudogap structure of underdoped cuprates becomes apparent at temperatures above the * critical temperature in the presence of diamagnetic fluctuations, in tunneling, photoemission, heat capacity measurements, and in the anomalous Nernst effect [5]. The pseudogap was found to have symmetry of the usual superconducting gap and it is substantially greater in value.…”

“…Another fundamental properties found in high-T c superconductors is the existence of a pseudogap ( * ) in the excitation spectrum of the superconductors [5]. The pseudogap structure of underdoped cuprates becomes apparent at temperatures above the * critical temperature in the presence of diamagnetic fluctuations, in tunneling, photoemission, heat capacity measurements, and in the anomalous Nernst effect [5].…”

Superconductivity from Repulsion: Ginzburg–Landau Phenomenology of Cuprates

“…In this paper, using a generalized Ginzburg-Landau approach, we present the concept of Coulomb SC pairing with large momentum (η K -pairing, by analogy with Yang's η -pairing [7]) and some of its applications to physics of cuprates [8].…”

“…This mechanism results in the order parameter which has no less than two complex components [5] that, under a description [6] in the framework of Ginzburg-Landau phenomenology (developed previously to the microscopic BCS theory: V. L. Ginzburg and L. D. Landau, 1950), should be determined by an equation system that can admit of more than BCS-like solution only. In this paper, using a generalized Ginzburg-Landau approach, we present the concept of Coulomb SC pairing with large momentum (η K -pairing, by analogy with Yang's η -pairing [7]) and some of its applications to physics of cuprates [8].…”