NOLM-NALM fiber ring laser

We study the bidirectional lightwave propagations in an erbium-doped fiber ring laser and an inverted-S fiber ring laser, and observe their optical bistability behaviors. We develop a model for the inverted-S fiber ring laser using nonlinear optical loop mirror and nonlinear amplifying loop mirror (NOLM-NALM) principle, which operates in the nonlinear region. Good agreements between the laser experimental performance and the developed model are achieved. The laser shows good switching and pulse compression capabilities. In addition, the laser model illustrates the route to chaotic operation via period doubling bifurcation, when the input power increases. We also obtain quasi-periodic operation when the laser is amplitude modulated experimentally.     

An extended autocorrelation method for estimation of blood velocity

The conventional autocorrelation method (AM) to estimate the blood velocity for color flow imaging (CFI) is based on the phase estimation of the autocorrelation function. In this paper, a new extended autocorrelation method (EAM) that uses both phase and magnitude of the two dimensional (depth and temporal direction) autocorrelation function for estimating the blood velocity is presented. It is shown that the EAM has similar performance as the cross-correlation method (CCM). Both of them have smaller estimation variance than the AM and have the ability to estimate velocities beyond the Nyquist velocity, but the EAM is more computationally efficient than the CCM. A 2-D blood flow signal with rectilinear velocity including the transit time effect has also been simulated and the results are presented in this paper. For comparison, the EAM and the CCM have been applied to the simulated signals in which the flow velocities are up to four times the Nyquist velocity. The EAM has been further verified by experimental RF data from the subclavian artery     

京九铁路加筋土挡墙离心模型试验

京九铁路加筋土挡墙的离心模型试验验证了其总体设计方案的稳定性。对加施材料、墙体、面板等的模拟技术及其相似牢进行了探讨。同时，对NHRI—50gt离心机数据来集系统及测试技术进行了介绍。     

固相微萃取—气相色谱—质谱法在烟草香味成分分析中的应用

采用固相微萃取-气相色谱-质谱(SPME-GC-MS)法定性分析烟叶和成品烟的挥发性香味成分,共鉴定了烟叶中的29种挥发性成分和成品烟中的20种挥发性成分。该方法简单、快速,适用于烟草样品的定性分析检测。     

The effect of oxidants on 2-MIB concentration with the presence of cyanobacteria.

In this study, the effect of three oxidants, sodium hypochlorite, potassium permanganate, and ozone, were tested for the removal of 2-MIB with presence of cyanobacteria. Algae in water samples from the source water of Feng-Shen waterworks (FSW), Taiwan were cultivated at 30 degrees C with continuous light at an intensity between 2,500 and 3,400 lux. During the cultivating process, water samples were analyzed for nutrients, light absorbance at 665 nm (A665), and 2-MIB concentration. The 2-MIB concentrations within the incubated samples increased to as high as 1,000 ng/L to 2,000 ng/L, although no extra nutrients were added to the raw water. After 2 to 3 days incubation, the intracellular 2-MIB concentration was as high as 70% of the total 2-MIB in the samples. The algae that developed were mainly cyanobateria, and more than 90% belonged to the Genus Oscillatorias. An almost 100% removal of both 2-MIB and geosmin in the raw water was observed after ozonation for 10 minutes at a dosing rate of 0.91 mg/l-min. Chlorine and permanganate were much less effective, both removing only about 11% of the 2-MIB within 60 minutes at oxidant concentration of 10 mg/l. Oxidation of the cultivated samples showed that chlorine and permanganate may damage algae cells causing them to release intracellular 2-MIB. During the 60 minutes of reaction time, the total 2-MIB concentrations (intracellular plus dissolved) varied by no more than 10%, however, the ratios between dissolved and total 2-MIB concentrations increased. Two effects of ozonation on the 2-MIB concentration in the cultivated samples were observed when the algae were young, namely 2-MIB release from damaged cells and 2-MIB oxidization. The rates of 2-MIB release and 2-MIB destruction were similar. However, old algae cells were more easily damaged. As a result, intracellular 2-MIB was released faster, and the soluble 2-MIB was destroyed more quickly by ozonation.     

Evolution of Scour Depth at Circular Bridge Piers

Experiments of bridge pier scour are carried out under steady and unsteady clear-water scour conditions with uniform and nonuniform sediments. Around the pier nose, the sediment size variation of surface bed materials is investigated, and a regressed formula is obtained for estimating the mixing layer thickness in terms of median sediment size and geometric standard deviation of grain size distribution. A method based on the mixing layer concept is developed for calculating the equilibrium scour depth in nonuniform sediment. Based on the experimental data of scour rate, a model simulating the scour-depth evolution under steady flow in nonuniform sediment is presented. By analyzing experimental data, a scheme is proposed for computing the scour-depth evolution under unsteady flow.     

Cross-Layer Communication With an Optical Packet Switched Network via a Message Injection Control Interface

Message injection control and queue management for an optical packet switched network is demonstrated via interoperation of a network with an optical interface buffer. In a time-slotted manner, cross-layer signaling is employed between the input buffer and network to dynamically reroute dropped payload packets with multiple wavelength-striped 10-Gb/s channels. At the output of the network, error-free transmission with bit-error-rates less than were confirmed, with an introduced power penalty of 3.5 dB.