422,689 research outputs found
Dynamic Identification for Control of Large Space Structures
This is a compilation of reports by the one author on one subject. It consists of the following five journal articles: (1) A Parametric Study of the Ibrahim Time Domain Modal Identification Algorithm; (2) Large Modal Survey Testing Using the Ibrahim Time Domain Identification Technique; (3) Computation of Normal Modes from Identified Complex Modes; (4) Dynamic Modeling of Structural from Measured Complex Modes; and (5) Time Domain Quasi-Linear Identification of Nonlinear Dynamic Systems
Plasma Surface Functionalization of AFP Manufactured Composites for Improved Adhesive Bond Performance
Application of carbon fiber reinforced polymer (CFRP) as a high-performance structural material has widespread application in the present aerospace industry. However, as-processed composite materials require a comprehensive surface treatment prior to bonding to remove contaminants and impart surface functionality and topography to overcome their poor adhesion properties. Atmospheric pressure plasma jet treatment (APPJT) has been increasingly garnering attention as an alternate method for surface preparation of CFRP. This method has been reported to achieve success in imparting favorable polar functional groups into the composite surfaces enhancing wettability and surface energy of the bonded surfaces. In some cases, APPJT has been demonstrated to remove contaminants or, in the case of silicones, convert them to silica. In this study, an atmospheric pressure plasma jet (APPJ) system was used for surface activation of a composite laid-up by an automated fiber placement (AFP) machine. Surface modifications prior to and after treatment were characterized using water contact angle (WCA) measurements, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Double cantilever beam (DCB) tests were performed to quantify the bonding performance of the composites. The results show a marked enhancement of the mode I interlaminar fracture toughness with the application of APPJT
The performance of 'Shariah'-compliant companies during and after the recession period : evidence from companies listed on the FTSE All World Index
On stabilization and control for the critical Klein-Gordon equation on a 3-D compact manifold
In this article, we study the internal stabilization and control of the
critical nonlinear Klein-Gordon equation on 3-D compact manifolds. Under a
geometric assumption slightly stronger than the classical geometric control
condition, we prove exponential decay for some solutions bounded in the energy
space but small in a lower norm. The proof combines profile decomposition and
microlocal arguments. This profile decomposition, analogous to the one of
Bahouri-G\'erard on , is performed by taking care of possible geometric
effects. It uses some results of S. Ibrahim on the behavior of concentrating
waves on manifolds
Ill-posedness of the cubic nonlinear half-wave equation and other fractional NLS on the real line
In this paper, we study ill-posedness of cubic fractional nonlinear
Schr\"odinger equations. First, we consider the cubic nonlinear half-wave
equation (NHW) on . In particular, we prove the following
ill-posedness results: (i) failure of local uniform continuity of the solution
map in for , and also for in the
focusing case; (ii) failure of -smoothness of the solution map in
; (iii) norm inflation and, in particular, failure of
continuity of the solution map in , . By a similar
argument, we also prove norm inflation in negative Sobolev spaces for the cubic
fractional NLS. Surprisingly, we obtain norm inflation above the scaling
critical regularity in the case of dispersion with .Comment: Introduction expanded, references updated. We would like to thank
Nobu Kishimoto for his comments on the previous version and for pointing out
the related article of Iwabuchi and Uriy
Normality of Monomial Ideals
Given the monomial ideal I=(x_1^{{\alpha}_1},...,x_{n}^{{\alpha}_{n}})\subset
K[x_1,...,x_{n}] where {\alpha}_{i} are positive integers and K a field and let
J be the integral closure of I . It is a challenging problem to translate the
question of the normality of J into a question about the exponent set
{\Gamma}(J) and the Newton polyhedron NP(J). A relaxed version of this problem
is to give necessary or sufficient conditions on {\alpha}_1,...,{\alpha}_{n}
for the normality of J. We show that if {\alpha}_{i}\epsilon{s,l} with s and l
arbitrary positive integers, then J is normal
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