109,739 research outputs found
On the well-posedness of the Schrödinger–Korteweg–de Vries system
No full textAbstractWe prove that the Cauchy problem for the Schrödinger–Korteweg–de Vries system is locally well-posed for the initial data belonging to the Sobolev spaces L2(R)×H−3/4(R), and Hs(R)×H−3/4(R) (s>−1/16) for the resonant case. The new ingredient is that we use the F¯s-type space, introduced by the first author in Guo (2009) [10], to deal with the KdV part of the system and the coupling terms. In order to overcome the difficulty caused by the lack of scaling invariance, we prove uniform estimates for the multiplier. This result improves the previous one by Corcho and Linares (2007) [6]
Joint Spatial-Temporal Layer Bit Allocation with S-Domain Dependent R-D Modeling
No full textA joint spatial-temporal layer (S-T) bit allocation problem for H.264/SVC is studied with dependent layer rate and distortion (R-D) models. We examine dependent R-D models based on the self-domain} (S-domain) analysis, where the R-D characteristics of a dependent coding unit are expressed as the R-D characteristics of its reference and/or base layers. With the proposed R-D models, the complex inter-layer dependency can be simplified to be a linear sum of functions of a single parameter. The joint bit allocation problem is formulated as an optimization problem by the Lagrangian method, which could be numerically solved using the proposed R-D models. As a result, we develop a low-complexity bit allocation scheme for the combined spatial and temporal scalability of H.264/SVC. It is shown by experimental results that our proposed bit allocation algorithm has achieved the coding performance significantly improved from current reference software JSVM. ? 2011 IEEE.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000298610800068&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Computer Science, Theory & MethodsImaging Science & Photographic TechnologyEICPCI-S(ISTP)
Kinematic Simulation and Structure Analysis of a Morphing Flap
No full textThis thesis presents a study on the design and analysis of a morphing flap
structure integrated with actuation mechanism for potential application to large
aircraft. Unlike the conventional rigid flap mounted on the wing trailing edge,
the morphing flap is designed as a unitized structural system integrated with
three primary components: the upper and lower flexible skins reinforced by
stringers, an eccentric beam actuation mechanism (EBAM) with discs fixed on it,
and the connection of the discs with the stringers. Based on the EBAM concept
proposed by Dr Guo in previous research [1], the current study has been
focused on the EBAM design and optimization, kinematic simulation and
structural modelling of the morphing flap.
Although a lot of efforts have been made to develop the morphing flap in
previous research, it is lack of detailed design of the disc-skin linkage and clear
view on the mechanism optimization in relation to the shape requirement. The
main objective of this research is to meet the morphing shape requirements and
calculate the actuation torque for a specified morphing flap. Firstly effort was
made to design and optimize the disc shape and locations in the EBAM for the
best matching of the specified morphing shape with minimum actuation torque
demand. It is found that minimum three discs are required and their locations
have little effect on the actuation torque. Secondly attention was focused on
designs of the disc and a C-linkage with the stringers. To ensure that the C-
linkage works in practice, a twisted stringer flange design was proposed. Thirdly
the actuation mechanism was integrated with the stiffened skin to play the role
of an active rib in the flap structure. Based on the design, FE modelling and
analysis of the morphing flap structure was carried out. The behaviour of the
morphing flap under the internal actuation and external aerodynamic load was
applied for stress analysis and detailed design of the structures. Finally the
kinematics of the integrated morphing flap was simulated by using CATIA to
demonstrate the feasibility and the effectiveness of the improved design
Global well-posedness of Korteweg–de Vries equation in H−3/4(R)
No full textAbstractWe prove that the Korteweg–de Vries initial-value problem is globally well-posed in H−3/4(R) and the modified Korteweg–de Vries initial-value problem is globally well-posed in H1/4(R). The new ingredient is that we use directly the contraction principle to prove local well-posedness for KdV equation in H−3/4 by constructing some special resolution spaces in order to avoid some ‘logarithmic divergence’ from the high–high interactions. Our local solution has almost the same properties as those for Hs (s>−3/4) solution which enable us to apply the I-method to extend it to a global solution
Data for 'Coherent Perfect Absorption of Single Photons in a Fibre Network'
No full textResearch data for the paper
Vetlugin, A. N., Guo, R., Xomalis, A., Yanikgonul, S., Adamo, G., Soci, C., & Zheludev, N. (Accepted/In press). Coherent Perfect Absorption of Single Photons in a Fibre Network. Applied Physics Letters.</span
Model based defect characterization in composites
No full textWork is reported on model-based defect characterization in CFRP composites. The work utilizes computational models of the interaction of NDE probing energy fields (ultrasound and thermography), to determine 1) the measured signal dependence on material and defect properties (forward problem), and 2) an assessment of performance-critical defect properties from analysis of measured NDE signals (inverse problem). Work is reported on model implementation for inspection of CFRP laminates containing multi-ply impact-induced delamination, with application in this paper focusing on ultrasound. A companion paper in these proceedings summarizes corresponding activity in thermography. Inversion of ultrasound data is demonstrated showing the quantitative extraction of damage properties.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
This proceeding appeared in Roberts, R., and S. Holland. "Model based defect characterization in composites." In AIP Conference Proceedings, vol. 1806, no. 1, p. 090015. AIP Publishing LLC, 2017, and may be found at
DOI: 10.1063/1.4974659.
Copyright 2017 Author(s).
Posted with permission
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Non-Isothermal Boundary in the Boltzmann Theory and Fourier Law.
No full textIn the study of the heat transfer in the Boltzmann theory, the basic problem is to construct solutions to the following steady problem: v⋅∇ x F=1 K n Q(F,F),(x,v)∈Ω×R 3 ,(0.1) v · ∇ x F = 1 K n Q ( F , F ) , ( x , v ) ∈ Ω × R 3 , ( 0.1 ) F(x,v)| n(x)⋅v<0 =μ θ ∫ n(x)⋅v ′ >0 F(x,v ′ )(n(x)⋅v ′ )dv ′ ,x∈∂Ω,(0.2) F ( x , v ) | n ( x ) · v < 0 = μ θ ∫ n ( x ) · v ′ > 0 F ( x , v ′ ) ( n ( x ) · v ′ ) d v ′ , x ∈ ∂ Ω , ( 0.2 ) where Ω is a bounded domain in R d ,1≤d≤3 R d , 1 ≤ d ≤ 3 , Kn is the Knudsen number and μ θ =1 2πθ 2 (x) exp[−∣ ∣ v∣ ∣ 2 2θ(x) ] μ θ = 1 2 π θ 2 ( x ) exp [ - | v | 2 2 θ ( x ) ] is a Maxwellian with non-constant(non-isothermal) wall temperature θ(x). Based on new constructive coercivity estimates for both steady and dynamic cases, for |θ−θ 0 |≤δ≪1 | θ - θ 0 | ≤ δ ≪ 1 and any fixed value of Kn, we construct a unique non-negative solution F s to (0.1) and (0.2), continuous away from the grazing set and exponentially asymptotically stable. This solution is a genuine non-equilibrium stationary solution differing from a local equilibrium Maxwellian. As an application of our results we establish the expansion F s =μ θ 0 +δF 1 +O(δ 2 ) F s = μ θ 0 + δ F 1 + O ( δ 2 ) and we prove that, if the Fourier law holds, the temperature contribution associated to F 1 must be linear, in the slab geometry
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