Mode Interactions and Sound Power Transmission Loss of Expansion Chambers

2006 ◽  
Vol 129 (2) ◽  
pp. 141-147 ◽  
Author(s):  
C. K. Lau ◽  
S. K. Tang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plane Wave ◽  
Industrial Application ◽  
Power Transmission ◽  
Transmission Loss ◽  
Wave Power ◽  
Sound Power ◽  
The Finite Element Method ◽  
Mode Interactions

The mode interactions and the sound transmission loss across the expansion chambers with and without tapered sections are studied by the finite element method in the present investigation. Results from chambers with symmetrical inlet and outlet suggest lower sound power transmission loss at frequencies below that of the first symmetrical transverse chamber mode when the tapered section angle is reduced. Weak sound power transmission loss is also observed for this chamber type at frequency higher than that of the first symmetrical duct mode. Numerous high and low sound power transmission loss regions are observed between these two eigenfrequencies. Higher plane wave power transmission loss can be found at smaller tapered section angle only if one of the chamber endings is not tapered. Such chamber bears important industrial application.

scholarly journals Utilization of the finite element method for the calculation and examination of underground power cable ampacity

2019 ◽  
Vol 8 (3) ◽  
pp. 257
Author(s):  
Mahmood Khalid Hadi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Power Transmission ◽  
Linear Interpolation ◽  
Distribution Model ◽  
Power Cable ◽  
The Finite Element Method ◽  
Regular Feature ◽  
Parameter Values ◽  
Element Method

Currently, the use of underground electric cables is a regular feature of present-day power transmission and distribution schemes. Issues related to economical limitations and the lack of adequate space led to the need for cables with an elevated current carrying capacity (ampacity). In order to achieve this objective, public services around the globe are focusing not only on better designs, but also on improving the level of precision in the context of cable parameter values. Precise parameter values are essential for ensuring that the replicated outcomes correspond sufficiently close to actual circumstances. While the conventional approach to ampacity calculation is through the IEC-60287 procedure, the numerical route is considered more specific and flexible. This endeavour harnesses the finite element method to conceive an innovative process for calculating the thermal field and ampacity of a cable. This process involves the crafting of a temperature field distribution model for scrutinizing temperature distribution in the region of an electric cable, and the deployment of the linear interpolation procedure for computing its ampacity. Subsequent to its formation, the model was put into operation on the underground cable 33KV XLPE.

Modeling and Design Optimization of Contactless Sliding Transformer System for Ropeless Elevators

2013 ◽  
Vol 416-417 ◽  
pp. 264-269
Author(s):  
Pei Long Wang ◽  
Xiao Zhuo Xu ◽  
Bao Yu Du ◽  
Hai Chao Feng ◽  
Xu Dong Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Permanent Magnet ◽  
Power Transmission ◽  
Electrical Power ◽  
Coupling Coefficients ◽  
The Finite Element Method ◽  
The Magnetic Field ◽  
Load Conditions

In this paper, two novel topological structures of sliding transformer with ferromagnetic core applied in the Contactless Electrical Power Transmission (CEPT) system used for the ropeless elevator driven by moving-coil type Permanent Magnet Synchronous Linear Motor (PMLSM) have been proposed, and the magnetic field distribution is calculated and analyzed by the finite element method (FEM). According to the analysis results of the traditional E-E topology sliding transformer, much higher coupling coefficients of sliding transformers with proposed topologies have been obtained. Then, based on the magnetic distribution and the circuit model of system, the compensation capacitances have been calculated considering supply frequency and load conditions. Finally, the load characteristic of the system with compensation is also obtained by FEM.

Optimization of sound transmission loss of open acoustic barriers with respect to unit cell topology

2021 ◽  
pp. 095440622199157
Author(s):  
Nan Li ◽  
Mabrouk Ben Tahar ◽  
Fusheng Sui
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Power Transmission ◽  
Transmission Loss ◽  
Design Method ◽  
Sound Transmission ◽  
Unit Cell ◽  
Sound Transmission Loss ◽  
Power Transmission Coefficient ◽  
Element Method

Open acoustic barriers exhibit excellent sound transmission reduction property at a certain frequency/frequencies which highly depends on the configuration of its unit cell. Design of unit cell configuration for minimum sound transmission at predefined objective frequency remains an open question. This paper aims at providing an automatic design method for open acoustic barriers with multi-material unit cell. Firstly, a wave finite element method is developed to calculate the sound transmission through an infinite array of periodic scatterers. As the unit cell contains infinite fluid domain, the application of Floquet-Bloch theorem to the boundaries of perfectly match layers (PML) is necessary and has been resolved in this paper. This wave finite element method with the implementation of PML is validated by comparing to analytical solution of sound transmission through an array of steel cylinders. Then a genetic algorithm is employed to optimize the sound transmission loss with respect to material distribution of a bi-material unit cell. Finally, the effectiveness of this inverse design is demonstrated by examples with different predefined frequencies. Corresponding unit cell typologies are obtained and the dips of sound power transmission coefficient curve are successfully tuned to objective frequencies.

scholarly journals Electromagnetic Scattering by a Cylinder in a Lossy Medium of an Inhomogeneous Elliptically Polarized Plane Wave

2019 ◽  
Vol 4 (2019) ◽  
pp. 36-42 ◽  
Author(s):  
Fabio Mangini ◽  
Lorenzo Dinia ◽  
Fabrizio Frezza
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electromagnetic Field ◽  
Plane Wave ◽  
Electromagnetic Scattering ◽  
The Finite Element Method ◽  
Matlab Code ◽  
Lossy Medium ◽  
Elliptically Polarized ◽  
Cylindrical Harmonics

In this paper, a rigorous theoretical approach, adopted in order to generalize the Vectorial CylindricalHarmonics (VCH) expansion of an inhomogeneous elliptically polarized plane wave, is presented. An application of the VCH expansion to analyze electromagnetic field scattered by an infinite circular cylinder is presented. The results are obtained using the so-called complex-angle formalism reaching a superposition of Vectorial Cylindrical-Harmonics. To validate the method, a Matlab code was implemented. Also, the validity of the methodology was confirmed through some comparisons between the proposed method and the numerical results obtained based on the Finite Element Method (FEM) in the canonical scenario with a single cylinder.

scholarly journals Influence of Viet Nam climatic condition on ampacity of overhead power transmission lines

2016 ◽  
Vol 19 (1) ◽  
pp. 20-30
Author(s):  
Nam Nhat Nguyen ◽  
Tuong Thien Tran ◽  
Tu Phan Vu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Transmission Lines ◽  
Climatic Condition ◽  
Power Transmission ◽  
Viet Nam ◽  
Power Transmission Lines ◽  
The Finite Element Method ◽  
Maximum Current ◽  
Overhead Power Transmission Lines

Based on our previous paper –[1], in which we have computed the ampacity of overhead power transmission lines with considering the influence of environmental conditions such as wind velocity, wind direction, temperature, and radiation coefficient on the typical line of ACSR, we continue in this paper to investigating the influence of Viet Nam climatic condition on the ampacity of overhead power transmission lines in twelve months of the year. The results obtained by the finite element method are compared with those computed by the IEEE standard have been shown the high accuracy and applicability of the finite element method. In particular, the comparison between our calculated results and the maximum current given by the design standard has been shown that if we monitor well the climatic condition, we can operate the real overhead transmission lines with the maximum current that is higher than the original design about several hundred amperes.

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