Browsing by Author "Liu, Ching-Yu"

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Microscopic Traffic Monitoring and Data Collection Cloud Platform Based on Aerial Video
(2020-01-01)
Chen, Guan-Wen
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Yeh, Tzu-Chuan
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Liu, Ching-Yu
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Ik, Tsi-Ui
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資訊工程學系
Real-time traffic video streaming, such as roadside surveillance and aerial video, has been widely used in traffic monitoring nowadays. However, most of the traditional traffic data collection methods lack mobility that can only collect macroscopic data. In this paper, an intelligent traffic monitoring system based on an open source cooperative platform called SAGE2 was developed. Based on the integrated big screen TV wall of SAGE2, a map-based aerial traffic video streaming management interface was designed. In the image pre-processing section, it provides functions such as lens distortion removal, top view projection transforms, and video stabilization; simulate video streaming to provide instant and long-term micro-flow data collection. Micro-traffic flow data provides high-resolution information both in time and space which can be used to analyze the driving behavior of individuals and the public. Combined with the lane level map, it can provide a variety of visual vehicle flow presentations, such as intersection traffic distribution that can also be used to develop an innovative application in the future.
. Modal Identification Of Structures From Seismic Response Data Via Amplitude-Dependent Time Series Model
(2014)
Su, Wei Chih
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Huang, Chiung Shiann
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Liu, Ching-Yu
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交大名義發表
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National Chiao Tung University
The present work develops a novel procedure of establishing an amplitude-dependent time series model for a nonlinear system and estimating the instantaneous modal parameters of the system from the dynamical responses. The undetermined coefficient in an amplitude-dependent autoregressive with exogenous input (amplitude-dependent ARX) model are assumed as functions of amplitude and are expanded by shape functions constructing by moving least-squares with polynomial basis functions. The amplitude of dynamical responses could be obtained by Hilbert transform. The instantaneous modal parameters of the system are directly estimated from the coefficient in the amplitude-dependent ARX model. Finally, the proposed approach is applied to process measured data for a frame specimen subjected to a series of base excitations in shaking table tests. The specimen was damaged during testing. The identified modal parameters are consistent with observed physical phenomena.
Optimization of Microspeaker Diaphragm Pattern Using Combined Finite Element-Lumped Parameter Models
(2008-08-01)
Bai, Mingsain R.
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Liu, Ching-Yu
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Chen, Rong-Liang
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機械工程學系
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Department of Mechanical Engineering
Microspeakers in portable devices are expected to meet a number of conflicting requirements such as miniaturization, high output level, and good sound quality. In contrast to large loudspeakers, the structures of microspeakers are generally simplified by removal of the suspension. The diaphragm serves as not only a sound radiator but also the suspension. Thus, the pattern design of the diaphragm is crucial to the overall response and performance of a microspeaker. The traditional approach for modeling microspeakers using lumped parameter models is generally incapable of modeling flexural modes in high frequencies. In this paper, we present a hybrid approach that combines finite-element analysis (FEA) and electro-mechano-acoustical (EMA) analogous circuit to provide a more accurate model than the conventional approaches. In particular, the minute details of diaphragms are taken into account in calculating the mechanical impedance of the diaphragm-voice coil assembly using FEA. The mechanical impedance is then incorporated into the lumped parameter model. The responses can be simulated by solving the loop equations. On the basis of this simulation model, we optimize the pattern design of the diaphragm using the Taguchi method. In addition, we determine the optimal number of diaphragm corrugations by using sensitivity analysis.