Browsing by Author "Wong, Yu-Ting"

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Iterative Training Signal Design for MIMO Multiuser Systems
(2013)
Fung, Carrson C.
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Wong, Yu-Ting
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
An iterative training sequence design scheme called Iterative SuperImposed training sequence design with Multiple Interferers, or ISIMI, is proposed for estimating MIMO channels with colored noise. The proposed approach decomposes the MIMO channel and design the training sequence on a per channel basis, thus making the use of sequential minimum mean-squared error (MMSE) estimator ideal for channel estimation. The time-multiplexed-superimposed training (TM-SIT) transmission format is also proposed to accommodate the different training sequences obtained via the proposed ISIMI method. The proposed approach does not use nonlinear optimization as utilized in previous literature, nor make any assumption about the lack of interdependence between the transmitter and receiver. The approach can be proven to converge to at least a local optimal solution and is shown consistently by Monte Carlo simulation to outperform previously proposed MMSE based approaches by 4 dB for 4x4 MIMO systems, respectively, in terms of MSE when the sequential MMSE estimator is used.
Removals of pharmaceuticals in municipal wastewater using a staged anaerobic fluidized membrane bioreactor
(2019-05-01)
Chen, Wei-Hsiang
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Wong, Yu-Ting
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Huang, Tsung-Hsien
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Chen, Wen-Hsing
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Lin, Jih-Gaw
The staged anaerobic fluidized membrane bioreactor (SAFMBR) is effective to remove organic substances with reduced sludge production by minimizing excess waste sludge. This study investigated the removals of four pharmaceuticals present at trace levels in municipal wastewater by using a SAFMBR. The target pharmaceuticals included ibuprofen, naproxen, carbamazepine, and diclofenac. A pilot-scale SAFMBR with hydraulic retention times (HRTs) from 4.5 to 13.5 hr was established and operated for 450 days with a municipal wastewater spiked with four pharmaceuticals. In the results, the BOD and COD removals were effective and limitedly affected the presence of pharmaceuticals. The BOD removal efficiencies in the anaerobic fluidized membrane bioreactor (AFBR) and anaerobic fluidized membrane bioreactor (AFMBR) were 63.5 +/- 28.6% and 81.6 +/- 25.1%, respectively. However, the treatment efficiencies of four pharmaceuticals varied. Naproxen that contains electron donating group was treated efficiently (63.8%similar to 72.1%), whereas the removal efficiencies of ibuprofen (25.0%similar to 32.4%), carbamazepine (16.6-18.5%), and diclofenac (non-detected) remained low. Ibuprofen was less efficient to compete with other electron acceptors in an anaerobic environment. For pharmaceuticals such as carbamazepine with a high acid dissociation constant (pKa = 13.9) or diclofenac with a high octanol-water partition coefficient (log K-ow = 4.51), sorption onto the sludge could be one critical process affecting their concentrations in the water phase. By being positively charged at neutral pH and/or hydrophobic, the pharmaceuticals were initially adsorbed onto sludge, followed by being desorbed when sludge decayed after long operating hours. Nitrogen balance was analyzed to indicate the decay of the bacteria in the AFMBR. Increasing the HRTs only slightly improved the treatment efficiencies (e.g., the naproxen removal was increased from 63.8% to 72.1% when the HRT was increased from 4.5 to 7.5 h). The different processes responsible for the removals of these pharmaceuticals were more critical and their effects were limitedly changed by HRT adjustment, indicating the importance of knowing the properties of a pharmaceutical for selection of a proper treatment approach.
Robust Chaos Lag Synchronization and Chaos Control of Double Mackey-Glass System by Noise Excitation of Parameters
(2013-01-01)
Yang, Cheng-Hsiung
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Wong, Yu-Ting
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Li, Shih-Yu
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Chang, Ching-Ming
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機械工程學系
Lag synchronization of two uncoupled double Mackey-Glass systems by parameter excited method is presented. By replacing the corresponding parameters with two lag Rayleigh noise signals, the lag synchronization can be successfully achieved. Numerical simulations show the proposed method is effective. Temporary lag synchronization, partial lag synchronization, chaos control and robustness of lag synchronization are also obtained by this method.
Temporary lag and anticipated synchronization and anti-synchronization of uncoupled time-delayed chaotic systems
(2008-11-25)
Ge, Zheng-Ming
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Wong, Yu-Ting
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Li, Shih-Yu
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機械工程學系
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Department of Mechanical Engineering
Without any control scheme and coupling terms, temporary lag and anticipated synchronization and temporary lag and anticipated anti-synchronization are newly discovered in two identical double Mackey-Glass systems with different initial conditions. When all initial conditions are positive, the lag synchronization is obtained. The negative initial values make the time history inverse and temporary lag anti-synchronization occur. The phenomena both appear intermittently. (C) 2008 Elsevier Ltd. All rights reserved.