Nonlinear oscillation and control in the BZ chemical reaction.

In this thesis, a reversible Lotka-Volterra model was proposed to study the nonlinear oscillation of the Belousov-Zhabotinsky(BZ) reaction in a closed isothermal chemical system. The reaction zone can be divided into two zones, oscillation zone and transition zone, where the oscillation time and the transition time and the number of the complete oscillations are estimated. By applying the geometric singular perturbation method, it was proved that there exist an oscillation axis in the oscillation zone, a strongly stable two-dimensional invariant manifold in transition zone, on which there is also a one-dimensional stable invariant manifold, which is the part of the central axis. There is no oscillation in the vicinity of the equilibrium, as indicated by Onsager's reciprocal symmetry relation. Furthermore, the damped oscillation is studied in terms of the action-action-angle variables. In the end, the model reference control technique is employed to control the oscillation amplitude in the BZ reaction.Ph.D.Committee Chair: Yi, Yingfei; Committee Member: Chow, Shui-Nee; Committee Member: Dieci, Luca; Committee Member: Verriest, Erik; Committee Member: Weiss, Howi

Circulator based on spoof surface plasmon polaritons

Circulators based on spoof surface plasmon polaritons are designed and analyzed. In the letter, we use blade structure to realize the propagation of SSPPs wave and a matching transition is used to feed energy from coplanar waveguide to the SSPPs. And the circulator shows good nonreciprocal transmission characteristics. The simulation results indicate that in the frequency band from 5 to 6.6 GHz, the isolation degree and return loss basically reaches 15dB and the insertion loss is less than 0.5dB. Moreover, the use of confinement electromagnetic waves can decrease the size of the ferrite and show a broadband characteristic.Comment: 3 pages, 6 figures, submitted to IEEE antennas and wireless propagation letters on 27-Mar-201

Incentive-Restricted Mechanism to Department Manager in the Process of Knowledge Transfer in the Guarantee Enterprise Under Condition of Asymmetric Information

Guarantee industry is recognized as the high-risk industry in the world, and business risks and personnel risks are two main risks that guarantee enterprises face. Nowadays, guarantee enterprises in China, have great requirements for high quality and ability of the business personnel, but the labor market cannot supply enough talented guarantee people, and this phenomenon highlights the importance and urgency for the guarantee enterprises to provide business personnel training programs. This paper uses the principal-agent theory to explain the incentive-restricted mechanism of preventing department managers’ moral hazard under the real condition of information asymmetry, and verify the validity of theory model of mathematical analysis through an empirical research

Fairness of ChatGPT

Understanding and addressing unfairness in LLMs are crucial for responsible AI deployment. However, there is a limited availability of quantitative analyses and in-depth studies regarding fairness evaluations in LLMs, especially when applying LLMs to high-stakes fields. This work aims to fill this gap by providing a systematic evaluation of the effectiveness and fairness of LLMs using ChatGPT as a study case. We focus on assessing ChatGPT's performance in high-takes fields including education, criminology, finance and healthcare. To make thorough evaluation, we consider both group fairness and individual fairness and we also observe the disparities in ChatGPT's outputs under a set of biased or unbiased prompts. This work contributes to a deeper understanding of LLMs' fairness performance, facilitates bias mitigation and fosters the development of responsible artificial intelligence systems

Effects of Carrier Materials on Anaerobic Hydrogen Production by Continuous Mixed Immobilized Sludge Reactors

To enhance hydrogen production rate and increase substrate utilization efficiency of anaerobic fermentation, three carrier materials, Granular Activated Carbon (GAC), Zeolite Molecular Sieve (ZMS) and Biological Ceramic Ring (BCR), were used as carrier materials in Continuous Mixed Immobilized Sludge Reactors (CMISRs). The effects of carrier materials and substrate organic loading rate (OLR, OLR = 12, 24, 36, 48 kg/m3/d) on biohydrogen production were investigate, respectively. The highest HPRs of ZMS, GAC and BCR were achieved under the OLR of 36 kg COD/m3/d, and were 2.01, 1.81, and 2.86 L/L/d, respectively. The highest COD removal efficiencies of ZMS, GAC and BCR were 38.95 % (OLR = 24 kg COD/m3/d), 36.47 % (OLR = 36 kg COD/m3/d), and 41.03 % (OLR = 36 kg COD/m3/d), respectively. The best substrate degradation rate of ZMS, GAC and BCR were 40.33 % (OLR = 24 kg COD/m3/d), 38.30 % (OLR = 24 kg COD/m3/d) and 45.60 % (OLR = 12 kg COD/m3/d). The results indicated that biological ceramic ring get better hydrogen production and wastewater treatment performance as sludge carrier material for hydrogen production in immobilized bioprocesses