Frequency Window Method for Strongly Coupled and Multiply Connected Structural Systems: Multiple-Mode Windows

1992 ◽  
Vol 59 (2S) ◽  
pp. S244-S252 ◽  
Author(s):  
K.-W. Min ◽  
T. Igusa ◽  
J. D. Achenbach
Keyword(s):  
Companion Paper ◽  
Structural System ◽  
Strongly Coupled ◽  
Multiply Connected ◽  
Multiple Mode ◽  
Window Method ◽  
Frequency Window ◽  
Rational Expressions ◽  
Insight Into ◽  
Reduced Problem

In a companion paper, a method is presented to analyze the dynamic behavior of a structural system consisting of a main structure and strongly coupled, multiply connected substructures. Lagrange’s equations are used to develop a characteristic equation for connected substructures in terms of substructure impedances and mobilities. A frequency window method is used to reduce the complexity of the problem by a decomposition of the impedance and mobility functions into dominant and higher-order rational expressions. From the reduced problem, simple expressions for the modal properties are developed using matrix algebraic methods, which provide insight into the resonance characteristics of the connected substructures. Onemode windows were discussed in detail and examples were presented. In the present paper the theory is extended to multiple-mode windows.

Frequency Window Method for Strongly Coupled and Multiply Connected Structural Systems: One-Mode Windows

1992 ◽  
Vol 59 (2S) ◽  
pp. S236-S243 ◽  
Author(s):  
Kyung-Won Min ◽  
Takeru Igusa ◽  
Jan D. Achenbach
Keyword(s):  
Iterative Procedure ◽  
Structural Systems ◽  
Structural System ◽  
Strongly Coupled ◽  
Multiply Connected ◽  
Window Method ◽  
Frequency Window ◽  
Rational Expressions ◽  
Insight Into ◽  
Reduced Problem

A method is presented to analyze the dynamic behavior of a structural system consisting of a main structure and strongly coupled, multiply connected substructures. Lagrange’s equations are used to develop a characteristic equation for connected substructures in terms of substructure impedances and mobilities. Then, a frequency window method is used to reduce the complexity of the problem by a decomposition of the impedance and mobility functions into dominant and highorder rational expressions. From the reduced problem, simple expressions for the modal properties are developed using matrix algebraic methods, which provide insight into the resonance characteristics of the connected substructures. Higherorder terms, which become significant for strongly coupled substructures, are included in the eigenvalue analysis by using an iterative procedure. It is shown that the frequency window method developed in this paper, used as a numerical scheme, produces results which converge to exact results after only a few iterations.

Effects of the SNAP25 on Integration Ability of Brain Functions in Children With ADHD

2020 ◽  
pp. 108705472096456
Author(s):  
Yue Yang ◽  
Gang Peng ◽  
Hongwu Zeng ◽  
Diangang Fang ◽  
Linlin Zhang ◽  
...  
Keyword(s):  
Time Window ◽  
Precentral Gyrus ◽  
Children With Adhd ◽  
Brain Functions ◽  
Lingual Gyrus ◽  
Window Method ◽  
Central Gyrus ◽  
The Right ◽  
The Brain ◽  
Insight Into

Objective: The present study aimed to examine the effects of SNAP25 on the integration ability of intrinsic brain functions in children with ADHD, and whether the integration ability was associated with working memory (WM). Methods: A sliding time window method was used to calculate the spatial and temporal concordance among five rs-fMRI regional indices in 55 children with ADHD and 20 healthy controls. Results: The SNAP25 exhibited significant interaction effects with ADHD diagnosis on the voxel-wise concordance in the right posterior central gyrus, fusiform gyrus and lingual gyrus. Specifically, for children with ADHD, G-carriers showed increased voxel-wise concordance in comparison to TT homozygotes in the right precentral gyrus, superior frontal gyrus, postcentral gyrus, and middle frontal gyrus. The voxel-wise concordance was also found to be related to WM. Conclusion: Our findings provided a new insight into the neural mechanisms of the brain function of ADHD children.

scholarly journals Modeling and Experimental Validation of the VARTM Process for Thin-Walled Preforms

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2003
Author(s):  
Da Wu ◽  
Ragnar Larsson ◽  
Mohammad S. Rouhi
Keyword(s):  
Shell Model ◽  
Computational Efficiency ◽  
Large Scale ◽  
Strongly Coupled ◽  
Thin Walled Structures ◽  
Simulation Based ◽  
Thin Walled ◽  
High Computational Efficiency ◽  
Insight Into ◽  
Vartm Process

In this paper, recent shell model is advanced towards the calibration and validation of the Vacuum-assisted Resin Transfer Molding (VARTM) process in a novel way. The model solves the nonlinear and strongly coupled resin flow and preform deformation when the 3-D flow and stress problem is simplified to a corresponding 2-D problem. In this way, the computational efficiency is enhanced dramatically, which allows for simulations of the VARTM process of large scale thin-walled structures. The main novelty is that the assumptions of the neglected through-thickness flow and the restricted preform deformation along the normal of preform surface suffice well for the thin-walled VARTM process. The model shows excellent agreement with the VARTM process experiment. With good accuracy and high computational efficiency, the shell model provides an insight into the simulation-based optimization of the VARTM process. It can be applied to either determine locations of the gate and vents or optimize process parameters to reduce the deformation.

FE Modeling of EB-FRP Strengthened RC Beams

2014 ◽  
Vol 1065-1069 ◽  
pp. 1147-1150
Author(s):  
Kang Liu
Keyword(s):  
Finite Element ◽  
Fe Model ◽  
Rc Beams ◽  
Fe Modeling ◽  
Test Results ◽  
Structural System ◽  
Externally Bonded ◽  
Insight Into

A finite element (FE) model for externally bonded FRP (EB-FRP) strengthened RC beams is developed to simulate the responses of the structural system, to gain a better insight into the mechanism of the system. Comparisons between the predictions of the model and test results are presented to demonstrate its capability and accuracy.

Surjectivity of the Taylor map for complex nilpotent Lie groups

2009 ◽  
Vol 146 (1) ◽  
pp. 177-195 ◽  
Author(s):  
BRUCE K. DRIVER ◽  
LEONARD GROSS ◽  
LAURENT SALOFF-COSTE
Keyword(s):  
Lie Algebra ◽  
Hermitian Form ◽  
Holomorphic Functions ◽  
Companion Paper ◽  
Wigner Transform ◽  
Enveloping Algebra ◽  
Taylor Map ◽  
Hörmander’S Condition ◽  
Simply Connected ◽  
Insight Into

AbstractA Hermitian formqon the dual space,*, of the Lie algebra,, of a simply connected complex Lie group,G, determines a sub-Laplacian, Δ, onG. Assuming Hörmander's condition for hypoellipticity, there is a smooth heat kernel measure, ρt, onGassociated toetΔ/4. In a companion paper [6], we proved the existence of a unitary “Taylor” map from the space of holomorphic functions inL2(G, ρt) ontoJt0(a subspace of) the dual of the universal enveloping algebra of. Here we give a very different proof of the surjectivity of the Taylor map under the assumption thatGis nilpotent. This proof provides further insight into the structure of the Taylor map. In particular we show that the finite rank tensors are dense inJt0when the Lie algebra is graded and the Laplacian is adapted to the gradation. We also show how the Fourier–Wigner transform produces a natural family of holomorphic functions inL2(G, ρt), for appropriatet, whenGis the complex Heisenberg group.

Influence of cyclobutane segments in cycloaliphatic decahydronaphthalene-containing copolyesters

2017 ◽  
Vol 29 (6) ◽  
pp. 750-756 ◽  
Author(s):  
Joseph M Dennis ◽  
Nicole A Fazekas ◽  
Ryan J Mondschein ◽  
Ramesh Ramakrishnan ◽  
Sergei Nazarenko ◽  
...  
Keyword(s):  
Low Temperature ◽  
Relaxation Times ◽  
Mechanical Analysis ◽  
Polymer Backbone ◽  
Positron Annihilation Lifetime ◽  
Temperature Superposition ◽  
Frequency Window ◽  
Chain Entanglements ◽  
Large Frequency ◽  
Insight Into

Melt transesterification polycondensation enabled the incorporation of rigid, cycloaliphatic diols (2,2,4,4-tetramethylcyclobutane-1,3-diol) into decahydronaphthalene-containing copolyesters, which resulted in amorphous, optically clear materials. Glass transition temperatures approached 155°C and followed predictable trends using the Fox equation for randomly sequenced copolymers. Dynamic mechanical analysis identified several low-temperature relaxations attributed to the complex motions of the decahydronaphthalate and cyclohexyl rings within the polymer backbone. Furthermore, incorporating cyclobutane rings suppressed the low-temperature local mobility, revealing a strong structural dependence on these relaxations. The rheological simplicity of these nonassociating chains permitted analysis over a large frequency window using time–temperature superposition. As a result, the characteristic relaxation times provided insight into chain dynamics and the propensity for chain entanglements. Finally, positron annihilation lifetime spectroscopy probed hole-free volume and reinforced the trends observed with oxygen permeability measurements.

scholarly journals Review of lattice supersymmetry and gauge-gravity duality

2015 ◽  
Vol 30 (27) ◽  
pp. 1530054 ◽  
Author(s):  
Anosh Joseph
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Gauge Theory ◽  
Gauge Theories ◽  
Strongly Coupled ◽  
The Status ◽  
Gauge Gravity ◽  
Gravity Duality ◽  
Insight Into

We review the status of recent investigations on validating the gauge-gravity duality conjecture through numerical simulations of strongly coupled maximally supersymmetric thermal gauge theories. In the simplest setting, the gauge-gravity duality connects systems of D0-branes and black hole geometries at finite temperature to maximally supersymmetric gauged quantum mechanics at the same temperature. Recent simulations show that nonperturbative gauge theory results give excellent agreement with the quantum gravity predictions, thus proving strong evidence for the validity of the duality conjecture and more insight into quantum black holes and gravity.

Adaptive Negative Stiffness: A New Structural Modification Approach for Seismic Protection

2013 ◽  
Vol 639-640 ◽  
pp. 54-66 ◽  
Author(s):  
Satish Nagarajaiah ◽  
Dharma T.R. Pasala ◽  
Andrei Reinhorn ◽  
Michael Constantinou ◽  
Apostolos A. Sirilis ◽  
...  
Keyword(s):  
Composite Structure ◽  
Permanent Deformation ◽  
Companion Paper ◽  
Negative Stiffness ◽  
Superior Performance ◽  
Structural System ◽  
Base Shear ◽  
Main Structure ◽  
Negative Stiffness Device ◽  
Yield Displacement

Yielding can be emulated in a structural system by adding an adaptive “negative stiffness device” (NSD) and shifting the “yielding” away from the main structural system-leading to the new idea of “apparent weakening” that occurs ensuring structural stability at all displacement amplitudes. This is achieved through an adaptive negative stiffness system (ANSS), a combination of NSD and a viscous damper. By engaging the NSD at an appropriate displacement (apparent yield displacement that is well below the actual yield displacement of the structural system) the composite structure-device assembly behaves like a yielding structure. The combined NSD-structure system presented in this study has a re-centering mechanism thereby avoids permanent deformation in the composite structure-device assembly unless, the main structure itself yields. Essentially, a yielding-structure is “mimicked” without any, or with minimal permanent deformation or yielding in the main structure. As a result, the main structural system suffers less accelerations, less displacements and less base shear, while the ANSS “absorbs” them. This paper presents comprehensive details on development and study of the ANSS/NSD. Through numerical simulations, the effectiveness and the superior performance of the ANSS/NSD as compared to a structural system with supplemental passive dampers is presented. A companion paper presents the NSD and its mechanics in detail.

Sign in / Sign up

Export Citation Format

Share Document