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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of Non-linear Two-Terminal Mass Components for Application to Vehicle Suspension Systems

Yang, Shuai January 2017 (has links)
To achieve passive vibration control, an adaptive flywheel design is proposed and fabricated from two different materials. The corresponding mathematical models for the adaptive flywheels are developed. A two-terminal hydraulic device and a two-terminal inverse screw device are introduced to analyze the two adaptive flywheels. Experiments are carried out to identify key parameters for both the two-terminal hydraulic system and the inverse screw system. The performance of three different suspension systems are evaluated; these are the traditional suspension system, the suspension system consisting of an ideal two-terminal device with constant flywheel and the suspension system consisting of an ideal two-terminal device with an adaptive flywheel (AFW suspension system). Results show that the AFW suspension system can outperform the other two suspension systems under certain conditions. The performance of a suspension system with the adaptive flywheel under different changing ratio is evaluated, and an optimal changing ratio is identified under certain circumstances. To obtain the steady-state response of the two-terminal device with adaptive flywheel, three different methods have been applied in this thesis. These methods are the single harmonic balance method, the multi-harmonic balance method and the scanning iterative multi-harmonic balance method, respectively. Compared to the single harmonic balance method, the multi-harmonic balance method provides a much more accurate system response. However, the proposed scanning iterative multi-harmonic balance method provides more accurate system response than the single harmonic balance method with much less computational effort.
2

Studies on fluorescence anisotropies of conjugated polyenes with two phenyl groups: excitation wavelength and solvent viscosity dependences

Kuo, Che-ming 23 July 2004 (has links)
none
3

A Novel Linear RF Transmitter Using High-Efficiency Power Amplifier Applied with Envelope Modulation

Chen, Yu-An 26 July 2005 (has links)
Abstract¡G This thesis mainly implemented an RF transmitter with high efficiency and high linearity. A Cartesian to Polar transformation was implemented by CORDIC algorithm using FPGA. By replacing the envelope detector and limiter in traditional envelope elimination and restoration transmitter, this technique not only achieves more accurate modulation quality, but also becomes more suitable for single chip system. Applying the first order delta-sigma modulation and highly efficient switching-mode DC converter, the envelope signal was amplified highly efficiently. Due to the class-E power amplifier having good linear relation between output voltage and supply voltage, the polar modulation transmitter can achieve high efficiency and high linearity simultaneously. Furthermore, this thesis purposed a new transmitter with two-terminal time-varying modulation. The IQ modulated signal was fed to the input terminal of class-E amplifier, while the envelope signal was used to amplitude modulate the voltage supply terminal. With dynamic input power control, the conversion efficiency and linearity are independent of output power in the purposed architecture. From the experimental results, while transmitting a QPSK-modulated CDMA2000 1x signal with 1.2288 Msps data rate, the transmitter achieve 48 % in drain efficiency, 47 dB in ACPR, and 6 % in EVM at the output power ranging from 10 to 22 dBm.
4

Design and Analysis of a Shock Absorber with a Variable Moment of Inertia Flywheel for Passive Vehicle Suspension

Xu, Tongyi 05 November 2013 (has links)
Conventional vehicle suspensions consist of a spring and a damper, while mass is rarely used. A mass, if properly used, can also create a damping-like effect. However, a mass has only one terminal which makes it difficult to be incorporated into a suspension. In order to use a mass to achieve the damping-like effect, a two-terminal mass (TTM) has to be designed. However, most of the reported TTMs are of fixed moment of inertia (TTM-CMI), which limits the further improvement of the suspension performance and responsiveness to changes in environment and driving conditions. In this study, a TTM-based vibration absorber with variable moment of inertia (TTM-VMI) is proposed. The main component of the proposed TTM absorber contains a hydraulic-driven flywheel with sliders. The moment of inertia changes with the positions of the sliders in response to the driving conditions. The performance of the proposed TTM-VMI absorber has been analyzed via dynamics modeling and simulation and further examined by experiments. The analysis results indicate that the TTM-VMI absorber outperforms the TTM-CMI design in terms of body displacement; and ride comfort, tire grip and suspension deflection for zero and impulse inputs with comparable performance for sinusoidal input.
5

Design and Analysis of a Shock Absorber with a Variable Moment of Inertia Flywheel for Passive Vehicle Suspension

Xu, Tongyi January 2013 (has links)
Conventional vehicle suspensions consist of a spring and a damper, while mass is rarely used. A mass, if properly used, can also create a damping-like effect. However, a mass has only one terminal which makes it difficult to be incorporated into a suspension. In order to use a mass to achieve the damping-like effect, a two-terminal mass (TTM) has to be designed. However, most of the reported TTMs are of fixed moment of inertia (TTM-CMI), which limits the further improvement of the suspension performance and responsiveness to changes in environment and driving conditions. In this study, a TTM-based vibration absorber with variable moment of inertia (TTM-VMI) is proposed. The main component of the proposed TTM absorber contains a hydraulic-driven flywheel with sliders. The moment of inertia changes with the positions of the sliders in response to the driving conditions. The performance of the proposed TTM-VMI absorber has been analyzed via dynamics modeling and simulation and further examined by experiments. The analysis results indicate that the TTM-VMI absorber outperforms the TTM-CMI design in terms of body displacement; and ride comfort, tire grip and suspension deflection for zero and impulse inputs with comparable performance for sinusoidal input.

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