scholarly journals Modelling and Analysis of Global Vibroacoustic Coupling Characteristics of a Rectangular Enclosure Bounded by a Flexible Panel

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Fei Xue ◽  
Beibei Sun
Keyword(s):  
Boundary Conditions ◽  
Structural Parameters ◽  
Sound Field ◽  
Coupled System ◽  
Structure Design ◽  
Transfer Factors ◽  
Coupling Property ◽  
Flexible Panel ◽  
Global Coupling ◽  
Coupling Characteristics

The interaction between the sound field in an enclosure and its flexible panel is a critical problem; the influence of structural parameters on global vibroacoustic coupling characteristics of the panel-enclosure system is very important. In this paper, a novel index of the global coupling level was first proposed to describe the global vibroacoustic coupling extent between multiple panel vibration modes and enclosure acoustical modes of the coupled system. Then, the influence of structural parameters on global coupling levels of the coupled system with different panel boundary conditions was obtained based on the numerical results of transfer factors. Moreover, according to the comprehensive influence of the structural parameters on global coupling levels, design methods of the coupled system with low global coupling levels were then discussed. Finally, the influence mechanism of panel boundary conditions on the coupling characteristics of the coupled system was analyzed. The results show that the structural parameters have similar effect on the coupling property of the system with different panel boundary conditions. Furthermore, the influence of the structural parameters on the coupling property of the system with a clamped panel is more sensitive than that of the system with a simply supported one. Furthermore, the structural parameters, especially the enclosure depth and panel thickness, are not completely negative correlated to the global coupling levels of the system. In conclusion, this study could provide a theoretical basis for acoustical design of the panel-enclosure system (e.g., rectangular vehicle cabins) with low global coupling level, as well as the lightweight structure design of the system.

scholarly journals Loading Performance of a Novel Shearer Drum Applied to Thin Coal Seams

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 358
Author(s):  
Kuidong Gao ◽  
Xiaodi Zhang ◽  
Liqing Sun ◽  
Qingliang Zeng ◽  
Zhihai Liu
Keyword(s):  
Rotational Speed ◽  
Production Efficiency ◽  
Loading Rate ◽  
Positive Impact ◽  
Structural Parameters ◽  
Helix Angle ◽  
Structure Design ◽  
Coal Seams ◽  
Coal Particles ◽  
Relationship Of

The poor loading performance of shearer drums restricts the development and production efficiency of coal in thin coal seams. Changing operation and structural parameters can improve the drum’s loading performance to some extent, but the effect is not obvious. A two-segment differential rotational speed drum (TDRSD) was proposed after analyzing the drum’s influence mechanism on coal particles. To further reveal the drum’s coal loading principle, the velocity, particles distribution, and loading rate were analyzed. The effect of the matching relationship of the rotational speed and helix angle between the front and rear drum are also discussed. The results show that a lower front drum rotational speed had a positive impact on improving the loading performance, and the loading rate first increases and then decreases with the increase in rear drum rotational speed. The optimal loading performance was obtained in the range 60–67.5 rpm. The front drum’s helix angle had no evident effect on loading performance, and the loading rate increase with the increase in the rear drum’s helix angle. The results provide a reference and guidance for operation parameters selection, structure design, and drum optimization.

scholarly journals On a Riemann–Liouville Type Implicit Coupled System via Generalized Boundary Conditions

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1205
Author(s):  
Usman Riaz ◽  
Akbar Zada ◽  
Zeeshan Ali ◽  
Ioan-Lucian Popa ◽  
Shahram Rezapour ◽  
...  
Keyword(s):  
Fixed Point ◽  
Fixed Point Theorem ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Coupled System ◽  
Initial Boundary ◽  
Liouville Type ◽  
Liouville Derivative ◽  
Banach Contraction ◽  
Generalized Boundary Conditions

We study a coupled system of implicit differential equations with fractional-order differential boundary conditions and the Riemann–Liouville derivative. The existence, uniqueness, and at least one solution are established by applying the Banach contraction and Leray–Schauder fixed point theorem. Furthermore, Hyers–Ulam type stabilities are discussed. An example is presented to illustrate our main result. The suggested system is the generalization of fourth-order ordinary differential equations with anti-periodic, classical, and initial boundary conditions.

scholarly journals A Self-Adjoint Coupled System of Nonlinear Ordinary Differential Equations with Nonlocal Multi-Point Boundary Conditions on an Arbitrary Domain

2021 ◽  
Vol 11 (11) ◽  
pp. 4798
Author(s):  
Hari Mohan Srivastava ◽  
Sotiris K. Ntouyas ◽  
Mona Alsulami ◽  
Ahmed Alsaedi ◽  
Bashir Ahmad
Keyword(s):  
Differential Equations ◽  
Boundary Conditions ◽  
Ordinary Differential Equations ◽  
Coupled System ◽  
Contraction Mapping Principle ◽  
Arbitrary Domain ◽  
Banach Contraction ◽  
Coupled Boundary Conditions ◽  
Banach Contraction Mapping Principle ◽  
Banach Contraction Mapping

The main object of this paper is to investigate the existence of solutions for a self-adjoint coupled system of nonlinear second-order ordinary differential equations equipped with nonlocal multi-point coupled boundary conditions on an arbitrary domain. We apply the Leray–Schauder alternative, the Schauder fixed point theorem and the Banach contraction mapping principle in order to derive the main results, which are then well-illustrated with the aid of several examples. Some potential directions for related further researches are also indicated.

Dynamic Characteristics Analysis of Cable-Rib Tension Deployable Antenna

2016 ◽  
Author(s):  
Liu Ruiwei ◽  
Hongwei Guo ◽  
Zhang Qinghua ◽  
Rongqiang Liu ◽  
Tang Dewei
Keyword(s):  
Dynamic Characteristics ◽  
Structural Parameters ◽  
Element Model ◽  
Structure Design ◽  
Antenna Structure ◽  
Characteristics Analysis ◽  
New Type ◽  
Dynamic Characteristics Analysis ◽  
The Finite Element Model ◽  
Weight Dynamic

Balancing stiffness and weight is of substantial importance for antenna structure design. Conventional fold-rib antennas need sufficient weight to meet stiffness requirements. To address this issue, this paper proposes a new type of cable-rib tension deployable antenna that consists of six radial rib deployment mechanisms, numerous tensioned cables, and a mesh reflective surface. The primary innovation of this study is the application of numerous tensioned cables instead of metal materials to enhance the stiffness of the entire antenna while ensuring relatively less weight. Dynamic characteristics were analyzed to optimize the weight and stiffness of the antenna with the finite element model by subspace method. The first six orders of natural frequencies and corresponding vibration modes of the antenna structure are obtained. In addition, the effects of structural parameters on natural frequency are studied, and a method to improve the rigidity of the deployable antenna structure is proposed.

scholarly journals Analysis of a Coupled System of Nonlinear Fractional Langevin Equations with Certain Nonlocal and Nonseparated Boundary Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zaid Laadjal ◽  
Qasem M. Al-Mdallal ◽  
Fahd Jarad
Keyword(s):  
Boundary Conditions ◽  
Coupled System ◽  
Fractional Integrals ◽  
Langevin Equations ◽  
Uniqueness Of Solutions ◽  
Caputo Fractional Derivatives ◽  
Nonseparated Boundary Conditions ◽  
New Type ◽  
Predictor Corrector ◽  
Derivatives Of

In this article, we use some fixed point theorems to discuss the existence and uniqueness of solutions to a coupled system of a nonlinear Langevin differential equation which involves Caputo fractional derivatives of different orders and is governed by new type of nonlocal and nonseparated boundary conditions consisting of fractional integrals and derivatives. The considered boundary conditions are totally dissimilar than the ones already handled in the literature. Additionally, we modify the Adams-type predictor-corrector method by implicitly implementing the Gauss–Seidel method in order to solve some specific particular cases of the system.

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