Structural Dynamics Optimization Based on a Hybrid Inverse Synthesis Method Using a Quadratic Approximation

2004 ◽  
Vol 126 (2) ◽  
pp. 253-259 ◽  
Author(s):  
Alain Schorderet ◽  
Thomas Gmu¨r
Keyword(s):  
Structural Dynamics ◽  
Shape Factor ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
The Novel ◽  
Synthesis Algorithm ◽  
Numerical Examples ◽  
Dynamic Constraints ◽  
Modal Synthesis ◽  
Synthesis Approach

This paper lies within the framework of the so-called redesign problem of structures subjected to dynamic constraints. A hybrid synthesis algorithm is developed, combining the truncated modal basis of the initial system and the spatial or material co-ordinates of an added component, which is modelled with shell-type finite elements parameterized with respect to a shape factor. Based upon a quadratic inverse formulation, the proposed technique shows several advantages in comparison to other synthesis methods, such as a refined sensitivity strategy, a powerful modal synthesis approach and a simplified optimization phase. Numerical examples are provided illustrating the capabilities of the novel procedure.

scholarly journals Fast structural dynamic modeling and analysis for horizontally folding wing

2021 ◽  
Vol 37 (3) ◽  
Author(s):  
Y. Ni ◽  
W. Zhang ◽  
Y. Lv
Keyword(s):  
Dynamic Modeling ◽  
Structural Dynamics ◽  
Dynamic Characteristics ◽  
Synthesis Method ◽  
Finite Model ◽  
Dynamics Modeling ◽  
Structural Dynamic ◽  
Modal Synthesis ◽  
Folding Wing ◽  
Fixed Interface

To investigate the structural dynamic characteristics of a folding wing effectively, a fast structural dynamic modeling approach is proposed. Firstly, the interface compatible relationship of the traditional fixed interface component modal synthesis method is modified, and the internal force of the interface is completely expressed in the structural dynamic equation, so that the influence of the connection stiffness on the wing structure dynamics can be considered. Then, on the basis of the fixed interface component modal synthesis method, the main mode of fixed-loaded interface is introduced to establish the mixed-loaded interface component modal synthesis method, which makes it feasible to accurately reflect the influence of elasticity and inertia of fuselage and outer wing on inner wing. The structural dynamics modeling method based on two different kinds of component modal synthesis method analyzed and deduced in detail. The application of component modal synthesis method in the fast structural dynamics modeling of folding wing is achieved. The whole program is compiled in MATLAB. At the same time, the dynamic characteristics of the folding wing with different folding angles, different connections and different connection positions is investigated. The results of the method proposed in this paper are compared with the results of the repeated finite model established in MSC.NASTRAN to verify the effectiveness from the aspects of natural frequency and vibration mode.

scholarly journals A Full-Aperture Image Synthesis Method for the Rotating Rectangular Aperture System Using Fourier Spectrum Restoration

Photonics ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 522
Author(s):  
Guomian Lv ◽  
Hao Xu ◽  
Huajun Feng ◽  
Zhihai Xu ◽  
Hao Zhou ◽  
...  
Keyword(s):  
Fourier Spectrum ◽  
Synthesis Method ◽  
Image Synthesis ◽  
Objective Evaluation ◽  
The Novel ◽  
Point Spread Functions ◽  
Synthesis Algorithm ◽  
Rectangular Aperture ◽  
Point Spread ◽  
Resolution Imaging

The novel rotating rectangular aperture (RRA) system provides a good solution for space-based, large-aperture, high-resolution imaging tasks. Its imaging quality depends largely on the image synthesis algorithm, and the mainstream multi-frame deblurring approach is sophisticated and time-consuming. In this paper, we propose a novel full-aperture image synthesis algorithm for the RRA system, based on Fourier spectrum restoration. First, a numerical simulation model is established to analyze the RRA system’s characteristics and obtain the point spread functions (PSFs) rapidly. Then, each image is used iteratively to calculate the increment size and update the final restored Fourier spectrum. Both the simulation’s results and the practical experiment’s results show that our algorithm performs well in terms of objective evaluation and time consumption.

Component Modal Synthesis Methods Based on Hybrid Models, Part I: Theory of Hybrid Models and Modal Truncation Methods

1994 ◽  
Vol 61 (1) ◽  
pp. 100-108 ◽  
Author(s):  
L. Jezequel ◽  
H. D. Seito
Keyword(s):  
Synthesis Method ◽  
Integral Operators ◽  
Hybrid Models ◽  
Force Distribution ◽  
Synthesis Methods ◽  
Displacement Distribution ◽  
New Methods ◽  
Modal Synthesis ◽  
Intermediate Problem ◽  
Modal Truncation

The assembly of structures along continuous boundaries poses great difficulties for expressing generalized boundary coordinates in modal synthesis, especially in the context of experiments. In order to solve such problems, a hybrid modal synthesis method is proposed in this study. This approach is based on the intermediate problem theory of Weinstein and brings out the duality between the formulation in displacement and the formulation in force. Generalized boundary coordinates are defined by introducing static deformations resulting from force distribution or displacement distribution along the boundaries depending on which formulation is to be used. By introducing integral operators associated with intermediate problems, two new methods of modal truncation can be proposed.

scholarly journals A Combination of Modal Synthesis and Subspace Iteration for an Efficient Algorithm for Modal Analysis within a FE-Code

2003 ◽  
Vol 10 (1) ◽  
pp. 27-35 ◽  
Author(s):  
M.W. Zehn
Keyword(s):  
Eigenvalue Problem ◽  
Modal Analysis ◽  
Efficient Algorithm ◽  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Problem Solver ◽  
Synthesis Methods ◽  
Combined Method ◽  
Subspace Iteration ◽  
Modal Synthesis

Various well-known modal synthesis methods exist in the literature, which are all based upon certain assumptions for the relation of generalised modal co-ordinates with internal modal co-ordinates. If employed in a dynamical FE substructure/superelement technique the generalised modal co-ordinates are represented by the master degrees of freedom (DOF) of the master nodes of the substructure. To conduct FE modal analysis the modal synthesis method can be integrated to reduce the number of necessary master nodes or to ease the process of defining additional master points within the structure. The paper presents such a combined method, which can be integrated very efficiently and seamless into a special subspace eigenvalue problem solver with no need to alter the FE system matrices within the FE code. Accordingly, the merits of using the new algorithm are the easy implementation into a FE code, the less effort to carry out modal synthesis, and the versatility in dealing with superelements. The paper presents examples to illustrate the proper work of the algorithm proposed.

Component Modal Synthesis Methods Based on Hybrid Models, Part II: Numerical Tests and Experimental Identification of Hybrid Models

1994 ◽  
Vol 61 (1) ◽  
pp. 109-116 ◽  
Author(s):  
L. Jezequel ◽  
H. D. Setio
Keyword(s):  
Synthesis Method ◽  
Hybrid Models ◽  
Synthesis Methods ◽  
Mass Loading ◽  
Frequency Range ◽  
Compatibility Conditions ◽  
Experimental Identification ◽  
Numerical Tests ◽  
Modal Synthesis ◽  
Vibration Tests

A double modal synthesis method in which compatibility conditions at substructure interfaces are ensured by the introduction of loaded modes is presented in this study. These loaded modes, which are obtained by introducing mass loading or stiffness loading along the boundaries, are used to define generalized boundary coordinates. Thus the hybrid models presented in the first part of this study are developed so that they can be derived from test data as results of independent modal identifications. Unlike in classical modal synthesis methods, in this double modal synthesis method, it is not necessary to clamp the interfaces, which is always difficult to carry out during vibration tests. By introducing loaded modes, generalized boundary coordinates which represent boundary deformability in the frequency range under study can be defined.

Torsional Vibration Analysis of Complicated Multi-Branched Shafting Systems by Modal Synthesis Method

2003 ◽  
Vol 125 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Chun-Ping Zou ◽  
Duan-Shi Chen ◽  
Hong-Xing Hua
Keyword(s):  
Torsional Vibration ◽  
Vibration Analysis ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Elastic Coupling ◽  
Improved Method ◽  
Modal Synthesis ◽  
Rigid Connection ◽  
Flexible Connections ◽  
Fixed Interface

The torsional vibration calculations of the complicated multi-branched system with rigid connection and flexible connections made up of elastic-coupling parts are very difficult to perform using conventional methods. In this paper, a modal synthesis method of torsional vibration analysis for the system is proposed. This approach is an improved method of Hurty’s fixed-interface and Hou’s free-interface modal synthesis methods. Because of the introduction of flexible substructure, the improved modal synthesis method can effectively treat the complicated system in which there exists a rigid connection and a flexible connection that is formed by an elastic-coupling part. When the calculation is performed, the complicated multi-branched system is divided into several substructures that are analyzed by FEM (finite element method) except the special elastic-coupling part that is defined as flexible substructure and treated individually. The efficiency of modal synthesis is improved by choosing suitable number of lower-frequency modes in modal synthesis. As an example of an application of this method, the analysis of torsional vibration of a cam-type engine shafting system is carried out both numerically and experimentally. The results show that the above kind of multi-branched shafting system can be analyzed effectively by the proposed method.

scholarly journals An Analysis of Distance Education Problems Experienced in Higher Education: A Meta-Synthesis Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Güngör Kil ◽  
Salih Uşun
Keyword(s):  
Higher Education ◽  
Distance Education ◽  
Synthesis Method ◽  
Learning Problems ◽  
Synthesis Process ◽  
Synthesis Methods ◽  
Financial Problems ◽  
Web Based ◽  
E Learning ◽  
Synthesis Approach

By using the meta-synthesis method, this study aims to analyze the studies on distance education problems experienced in higher education. The data were gathered by using the "higher education problems", "e-learning problems", "online learning problems", "open education problems", "web-based learning problems" keywords in Google Academic and TUBITAK ULAKBIM (https://ulakbim.tubitak.gov.tr/) databases. A total of 23 articles meeting the predetermined criteria were included in the study. These articles were analyzed by using the thematic synthesis approach, one of the meta-synthesis methods. The meta-synthesis process developed by Walsh and Downe (2005) was followed in the analysis. Established codes and themes were presented in frequency tables and interpreted. The distance education problems experienced in higher education were discussed under five categories as the "problems relevant to students", "problems relevant to instructors", "systemic and administrative problems", "problems relevant to curriculum", and "infrastructure and financial problems". Among these problems, the "problems relevant to students" category was found to have the highest frequency while the "infrastructure and financial problems" had the lowest frequency.

scholarly journals Interrelations of Synthesis Method, Polyethylene Glycol Coating, Physico-Chemical Characteristics, and Antimicrobial Activity of Silver Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2475
Author(s):  
Amirah Shafilla Mohamad Kasim ◽  
Arbakariya Bin Ariff ◽  
Rosfarizan Mohamad ◽  
Fadzlie Wong Faizal Wong
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Polyethylene Glycol ◽  
Pathogenic Bacteria ◽  
Synthesis Method ◽  
Chemical Characteristics ◽  
Synthesis Methods ◽  
Uniform Size ◽  
Transmission Electron Microscopy Analysis ◽  
Physico Chemical

Silver nanoparticles (AgNPs) have been found to have extensive biomedical and biological applications. They can be synthesised using chemical and biological methods, and coated by polymer to enhance their stability. Hence, the changes in the physico-chemical characteristics of AgNPs must be scrutinised due to their importance for biological activity. The UV-Visible absorption spectra of polyethylene glycol (PEG) -coated AgNPs displayed a distinctive narrow peak compared to uncoated AgNPs. In addition, High-Resolution Transmission Electron Microscopy analysis revealed that the shapes of all AgNPs, were predominantly spherical, triangular, and rod-shaped. Fourier-Transform Infrared Spectroscopy analysis further confirmed the role of PEG molecules in the reduction and stabilisation of the AgNPs. Moreover, dynamic light scattering analysis also revealed that the polydispersity index values of PEG-coated AgNPs were lower than the uncoated AgNPs, implying a more uniform size distribution. Furthermore, the uncoated and PEG-coated biologically synthesised AgNPs demonstrated antagonisms activities towards tested pathogenic bacteria, whereas no antagonism activity was detected for the chemically synthesised AgNPs. Overall, generalisation on the interrelations of synthesis methods, PEG coating, characteristics, and antimicrobial activity of AgNPs were established in this study.

scholarly journals Hydrothermal Synthesis and Structural Investigation of a Crystalline Uranyl Borosilicate

Inorganics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 25
Author(s):  
Kristen A. Pace ◽  
Vladislav V. Klepov ◽  
Mark D. Smith ◽  
Travis Williams ◽  
Gregory Morrison ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Exploratory Research ◽  
The Novel ◽  
Orthorhombic Space Group ◽  
Crystalline Materials ◽  
Waste Remediation ◽  
And Storage ◽  
X Ray Absorption

The relevance of multidimensional and porous crystalline materials to nuclear waste remediation and storage applications has motivated exploratory research focused on materials discovery of compounds, such as actinide mixed-oxoanion phases, which exhibit rich structural chemistry. The novel phase K1.8Na1.2[(UO2)BSi4O12] has been synthesized using hydrothermal methods, representing the first example of a uranyl borosilicate. The three-dimensional structure crystallizes in the orthorhombic space group Cmce with lattice parameters a = 15.5471(19) Å, b = 14.3403(17) Å, c = 11.7315(15) Å, and V = 2615.5(6) Å3, and is composed of UO6 octahedra linked by [BSi4O12]5− chains to form a [(UO2)BSi4O12]3− framework. The synthesis method, structure, results of Raman, IR, and X-ray absorption spectroscopy, and thermal stability are discussed.

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