Browsing by Author "Chang, HT"

Now showing 1 - 4 of 4

A principal component based probabilistic DBNN for face recognition
(1996)
Shen, LJ
;
Fu, HC
;
Xu, YY
;
Hsu, FR
;
Chang, HT
Biodegradation of nitrilotriacetic acid and its metal complexes in river water
(1996)
Chen, SY
;
Lin, JG
;
Chang, HT
;
交大名義發表
;
環境工程研究所
In this work, we investigated the biodegradability of both the complexing agent (nitrilotriacetic acid, NTA) and its various metal complexes in an aquatic environment. A laboratory experiment was used to simulate the rates of biodegradation of NTA and NTA-metal (Ca, Pb, Zn, and Cu) complexes in river water. A first-order reaction was applied to describe the rates of biodegradation of NTA and NTA-metal complexes. NTA became completely degraded within 2 - 3 d after acclimation for 6 d and the rate coefficient (k) was 1.56 - 4.54 d(-1). Except Ca-NTA, all NTA-metal complexes degraded at a more smaller rate than NTA. The stabilities of these complexes are in the decreasing order Cu-NTA > Pb-NTA > Zn-NTA > Ca-NTA.
Frame-based subband Kalman filtering for speech enhancement
(1998)
Wu, WR
;
Chen, PC
;
Chang, HT
;
Kuo, CH
;
電信工程研究所
Kalman Filtering is an effective speech enhancement technique, in which speech and noise signals are usually modeled as autoregressive (AR) processes and represented in the state-space domain. Since AR coefficients identification and Kalman filtering require extensive computations, practical implementation of this approach is difficult. This paper proposes a simple and practical scheme that overcomes these problems. Speech signals are first decomposed into subbands. Subband speech signals are then modeled as low-order AR processes, such that low-order Kalman filters can be applied. Enhanced fullband speech signals are finally obtained by combining the enhanced subband speech signals. Using a frame-based algorithm, autocorrelation functions of subband speech are calculated and the Yuler-Walker equations are solved to obtain the AR parameters. Simulation results show that Kalman filtering in the subband domain not only greatly reduces the computational complexity but also achieves better performance compared to that in the fullband domain.
Mobilization kinetics of heavy metals by NTA and EDTA from contaminated river sediment
(1996)
Lin, JG
;
Chen, SY
;
Chang, HT
;
交大名義發表
;
環境工程研究所
In this study, a sediment sample was collected from a contaminated river. A laboratory batch experiment was used to simulate the mobilization of heavy metals from river sediments with varied concentrations of NTA and EDTA. The results show that there were two-stages of desorption in the mobilization of heavy metals from the sediment. As the concentrations of NTA and EDTA ranged 0-100 mg/l the mobilization percentages of heavy metals were proportional to the logarithm values of the concentrations of NTA and EDTA The physical meaning of the multiple first-order reaction was significant for the actual condition, but occasionally, it had more errors for Cu and Zn in the initial time.