The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Tong Gao - One of the best experts on this subject based on the ideXlab platform.

  • a comparative study of dynamic analysis methods for structural topology optimization under harmonic force excitations
    Structural and Multidisciplinary Optimization, 2015
    Co-Authors: Hu Liu, Weihong Zhang, Tong Gao
    Abstract:

    This work is focused on the topology optimization related to harmonic responses for large-scale problems. A comparative study is made among Mode Displacement method (MDM), Mode acceleration method (MAM) and full method (FM) to highlight their effectiveness. It is found that the MDM results in the unsatisfactory convergence due to the low accuracy of harmonic responses, while MAM and FM have a good accuracy and evidently favor the optimization convergence. Especially, the FM is of superiority in both accuracy and efficiency under the excitation at one specific frequency; MAM is preferable due to its balance between the computing efficiency and accuracy when multiple excitation frequencies are taken into account.

Weihong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • structural topology optimization under harmonic base acceleration excitations
    Structural and Multidisciplinary Optimization, 2018
    Co-Authors: Jihong Zhu, Weihong Zhang, Tao Liu, Qinglin Liu, Chong Yang
    Abstract:

    This work is focused on the structural topology optimization methods related to dynamic responses under harmonic base acceleration excitations. The uniform acceleration input Model is chosen to be the input form of base excitations. In the dynamic response analysis, we propose using the large mass method (LMM) in which artificial large mass values are attributed to each driven nodal degree of freedom (DOF), which can thus transform the base acceleration excitations into force excitations. Mode Displacement method (MDM) and Mode acceleration method (MAM) are then used to calculate the harmonic responses and the design sensitivities due to their balances between computing efficiency and accuracy especially when frequency bands are taken into account. A density based topology optimization method of minimizing dynamic responses is then formulated based on the integration of LMM and MDM or MAM. Moreover, some particular appearances such as the precision of response analysis using MDM or MAM, and the duplicated frequencies are briefly discussed. Numerical examples are finally tested to verify the accuracy of the proposed schemes in dynamic response analysis and the quality of the optimized design in improving dynamic performances.

  • a comparative study of dynamic analysis methods for structural topology optimization under harmonic force excitations
    Structural and Multidisciplinary Optimization, 2015
    Co-Authors: Hu Liu, Weihong Zhang, Tong Gao
    Abstract:

    This work is focused on the topology optimization related to harmonic responses for large-scale problems. A comparative study is made among Mode Displacement method (MDM), Mode acceleration method (MAM) and full method (FM) to highlight their effectiveness. It is found that the MDM results in the unsatisfactory convergence due to the low accuracy of harmonic responses, while MAM and FM have a good accuracy and evidently favor the optimization convergence. Especially, the FM is of superiority in both accuracy and efficiency under the excitation at one specific frequency; MAM is preferable due to its balance between the computing efficiency and accuracy when multiple excitation frequencies are taken into account.

R. J. Waltman - One of the best experts on this subject based on the ideXlab platform.

  • Vibrational Spectra of Diamond C(111)-(2x1) Exposed to Hydrogen and Methane: Comparison of Theory and Experiment
    The Journal of Physical Chemistry, 1995
    Co-Authors: J. Pacansky, R. J. Waltman
    Abstract:

    Optimized geometrics, energies, vibrational frequencies and normal Mode Displacement vectors using ab initio SCF calculations at the STO-3G and 3-21G level of theory are reported for two clusters based on the diamond lattice, isotetramantane, C[sub 22]H[sub 28], and methylisotetramantane, C[sub 23]H[sub 30]. Additionally, molecular mechanics on larger diamond clusters, [approx]C[sub 140], are also reported. The calculated vibrational spectra, together with the normal Mode Displacement vectors, are used to assign infrared-visible sum-frequency generation spectra of hydrogen-truncated diamond -(1 x 1) and methyl-truncated diamond -(1 x 1). 29 refs., 9 figs., 4 tabs.

Chong Yang - One of the best experts on this subject based on the ideXlab platform.

  • structural topology optimization under harmonic base acceleration excitations
    Structural and Multidisciplinary Optimization, 2018
    Co-Authors: Jihong Zhu, Weihong Zhang, Tao Liu, Qinglin Liu, Chong Yang
    Abstract:

    This work is focused on the structural topology optimization methods related to dynamic responses under harmonic base acceleration excitations. The uniform acceleration input Model is chosen to be the input form of base excitations. In the dynamic response analysis, we propose using the large mass method (LMM) in which artificial large mass values are attributed to each driven nodal degree of freedom (DOF), which can thus transform the base acceleration excitations into force excitations. Mode Displacement method (MDM) and Mode acceleration method (MAM) are then used to calculate the harmonic responses and the design sensitivities due to their balances between computing efficiency and accuracy especially when frequency bands are taken into account. A density based topology optimization method of minimizing dynamic responses is then formulated based on the integration of LMM and MDM or MAM. Moreover, some particular appearances such as the precision of response analysis using MDM or MAM, and the duplicated frequencies are briefly discussed. Numerical examples are finally tested to verify the accuracy of the proposed schemes in dynamic response analysis and the quality of the optimized design in improving dynamic performances.

A. E. Siegman - One of the best experts on this subject based on the ideXlab platform.

  • Optical Mode properties of laterally offset gain and index guiding structures
    IEEE Journal of Quantum Electronics, 1996
    Co-Authors: A. E. Siegman
    Abstract:

    We describe the Mode properties of offset gain and index guided structures in which gain and index guiding effects are simultaneously present and oriented in parallel but laterally offset. Such structures can occur in semiconductor lasers, integrated optics, and optical waveguides. Within the parabolic approximation the resulting waveguide Modes are found to be Hermite-Gaussian functions with complex-valued Gaussian Mode parameters and centerlines. The lateral positions and far-field angles of these Modes can be controlled by modifying the gain and index guiding parameters, permitting both transverse Mode Displacement and output beam steering.

  • Thermally controlled lateral beam shift and beam steering in semiconductor lasers
    IEEE Photonics Technology Letters, 1995
    Co-Authors: Y. Sun, C.g. Fanning, S.a. Biellak, A. E. Siegman
    Abstract:

    We demonstrate a thermally controlled, offset-gain and index-guiding (OGIG) structure, which permits continuous control of output beam position and direction from a semiconductor laser. The gain and index guiding axes in this structure are parallel but transversely offset. For parabolic gain and index profiles the resulting Modes will be Hermite-Gaussian Modes with complex-valued spot sizes and tilted wavefronts such that the beam emerges from the end face at a tunable angle with respect to the facet normal. An experimental demonstration of thermally controlled Mode Displacement and beam steering by as much as 15/spl deg/ is obtained by applying asymmetric heating to a semiconductor laser using a microstripe heater. >