Papers by Keyword: Transfer Matrix Method (TMM)

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Authors: Ke Ming Wang, Song Xiang
Abstract: Understanding dynamic behavior of a rotor system with a transverse crack is of great significance for operation reliability of rotating machinery. The transfer matrix method is widely used for rotor dynamic analysis, but it encounters difficulties modeling a crack. This study proposes a finite-width crack model that simulates the local stiffness reduction effect of a gaping crack in transfer matrix method. This model is obtained by comparing finite element analysis results of a shaft with a zero-width crack and its counterpart transfer matrix calculation results with a trial equivalent finite-width slot. Different shaft geometry and loading modes are considered to improve the generality of the model. An application example is given that uses the proposed model to calculate critical speeds of a multi-disk rotor system with a transverse crack at different positions.
Authors: Chien Jang Wu, Ya Ju Lee, Tzu Chyang King, Wen Kai Kuo
Abstract: A design of multichannel transmission filter at microwave is proposed. It is based on the use of the finite plasma photonic crystal operating at frequency below the plasma frequency. We consider a design structures of (AB)qA, where A is the dielectric material, B is the plasma layer, and q is the number of periods. It is found that the number of channels is equal to q-1. We show that the locations such multiple channels are in the pass band of the infinite plasma-dielectric photonic crystal. The idea of such design is thus to engineer the photonic pass band, which is fundamentally different from the usual design by engineering the photonic stop band like the multilayer Fabry-Perot transmission filter. The physical mechanism of multiple channels is also discussed.
Authors: Mihaela Suciu
Abstract: The paper presents an analytical calculus for the bending beams on elastic environment. The elastic environment sends in all points a reaction force proportional to the deformation with the same constant of proportionality in all points. The calculus of the state vectors associated at the origin section and at the end section of the beam is made by Transfer-Matrix Method, putting the conditions on the supports (extremities) of the beam. After, we can calculate all state vectors for all sections of the beam.
Authors: Mihaela Suciu
Abstract: The spring studies are very important for a lot of industry domains. We find the classical spring’s calculus in [2]. With the Transfer-Matrix Method, we can write the basic equations of the spring's theory with Dirac's and Heaviside's functions and operators and so we can calculate the six elements of the origin state vector. We have deducted the general expression for the Transfer-Matrix of a round spring, with an application for a spring embedded at its tow edges with uniform radial charge density. After, we can calculate, in all spring sections, the state vectors. We have studied a circular spring with a constant inertia and we have kept the sign conventions-as well as to the beams-for the internal efforts, for the displacements and for the exterior loads.
Authors: Xiang Yang Jin, Xiang Yi Guan, Li Li Zhao, He Teng Wang, Zhi Hui Sun
Abstract: Analyze the dynamic characteristics of long tooth height gear transmission system by using transfer-matrix method. Firstly, set up a calculation model of level 2 transmission system for long tooth height gear and master gear and construct the transfer equation and transfer matrix of all components, then calculate the rigidity and rotational inertia of the system and know the natural frequency and dominant mode of the whole system through the computer, at last, analyze and compare two systems and prove the superiority of long tooth height gear for reducing vibration and lowering noise.
Authors: Ke Ming Wang, Song Xiang
Abstract: Crack detection of critical beam structures such as bridges and aircraft wings by vibration monitoring is based on understanding how a crack affects the vibration characteristics of a beam structure. Transfer matrix method is a convenient, effective, and hence widely used approach to beam vibration analysis, but a crack in the beam makes this method ineffective. This paper proposes an open crack model that simulates the local stiffness reduction effect of a transverse crack by a rectangular slot to make the transfer matrix method able to analyze vibrations of a cracked beam. The depth of the slot is identical to the depth of the crack, and the equivalent width of the slot is obtained by comparison of stiffness reductions of finite element analysis results and the counterpart transfer matrix method results. Different dimensions of rectangular beams, different crack positions and loading conditions are considered and statistic method is used to improve the generality and accuracy of the model. A calculation example of a cracked cantilever beam is given and the validity of the proposed model is verified with available results of existing models.
Authors: Ji Jiang Wu, Jin Xia Gao
Abstract: The position-dependent extraordinary optical properties in near-zero-permittivity range for a one-dimensional superconducting photonic crystal consisting of alternating superconductor and dielectric layers are theoretically investigated by using the transfer matrix method. Based on the calculated reflectance spectrum, it is shown the extraordinary optical propriety depends on the relative position between the threshold wavelength and the photonic band gap. By suitably choosing the thickness of the superconducting or dielectric layer, one can design a transmission narrowband filter or resonator to satisfy their needs without introducing any physical defect in a superconducting photonic crystal.
Authors: Ulhas S. Sonawane, E.P. Samuel, Chetan Kasar, D.S. Patil
Abstract: Using Transfer Matrix Method (TMM) the Eigen energy of the GaN/AlGaN quantum wire has been evaluated. Peak density results show the confinement and tunneling of electron distribution in quantum wire due to band offset of GaN (wire region) and AlGaN (barrier region). The impact of this band offset results in variation in Eigen energy and is significant in Tunneling phenomenon study to realize the transmission coefficient across the cross-section. Our analysis reveals that for wider wires transmission coefficient reaches to its peak for lower Eigen energy values. Likewise, increase in aluminum mole fraction in AlGaN decreases tunneling effect.
Authors: Fei Wu, Chao Hua Jiang, Shen Zhang, Ying Di Liao, Feng Ouyang
Abstract: This paper, based on the calculation model of vertical elastic grade beam, puts forward transfer Matrix method model for calculation of sheet pile. Through setting virtual elastic support and calculating elasticity coefficient, sheet pile structure is applied to transfer Matrix method. According to the boundary conditions of sheet pile, establishing formulas to solve the initial vector , and getting the sheet pile arbitrary state vector . Using this method for a underground continuous wall structure to calculate, The results with the finite element method results come very close.
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