Corrosion of steel in structures has become a major cause of structural degradations. Corrosion detection and monitoring
are necessary for evaluation of structural service conditions. A novel FBG based sensor for steel corrosion detection and
monitoring is developed previously. In this paper the sensor performances are evaluated by comparing to the corrosive
rate of rebars in the corrosive environments. The correlation between the wavelength shifts of the sensor and the
corrosive depth is established. It is proved that the sensor responses successfully to the occurrence of rebar corrosion,
which shows the promising feasibility of applying the sensor for corrosion indicator.
Electro-optic properties of a cross-linked second order nonlinear optical polymer were reported. This polymer was
synthesized via the crosslinking reaction with cross linker Trimethylolmelamine by doping the chromophores into the
cellulose diacetate system. The crosslinking temperature is 144°C. The electro-optic coefficient was measured to be 7.12
pm/v at 1550 nm after poling. The stability characteristic of electro-optic effects was studied by a combination of the
electro-optic coefficient and dielectric relaxation measurements. Results show that the cross-linked electro-optic polymer
system possesses an excellent long-time stability. The average relaxation time is as large as 5880 days and the relaxation
was modeled by KWW equation. The dielectric analyses show that the temperature dependence of the relaxation time
follows Arrhenius law.
A time-domain optical add-drop multiplexing (OADM) technology using microring resonators is reported. Design and simulation are presented. The microring resonator is predicted to be fabricated by using Pockler electro-optic materials. The microring resonators possess a multistage-cascaded structure to satisfy the requirement to generate switching windows. Cascaded coupled microring resonator can expand the single resonant point into a box-like resonant region and reduce the wings of resonant curve. While multistage resonators are used and a certain shift of the resonant region is arranged between the stages, the total resonant region can be expanded further. We achieve the shift of the resonant region between the two stages by selecting different ring radii. The resulted microring resonators possess a box-like characteristic with shape wings. The OADM includes two microring resonators (MMRs) driven by sine wave voltages, one is used to accomplish the add function the other is used to accomplish the drop function. The only operation differences between the two MMRs are the bias voltage and the phase of the driving signal. The OADM only requires electrical control signal and simple structure instead of high-quality optical control pulse and interferometer structure. FDTD simulation results show that the resonators can stratify the requirements to generate complementary switching windows for OADM operation.
KEYWORDS: Geographic information systems, Telecommunications, Navigation systems, Fluorescence correlation spectroscopy, Wireless communications, Data communications, Error control coding, Network architectures, Global Positioning System, Mobile communications
Self-organized time division multiple access ( SOTDMA) is an advanced wireless communication technology used in quick automatic networking. Also self-organized network is an equity network, which is provided with selforganized characteristics. First, the paper analyses the technology and characteristics of self-organized network and
puts forward network architecture with self-organized model for different environments. Then it discusses the message transport protocol of SOTDMA, further gives a clear description of the functions for each layer in the network architecture. Second, the paper studies the access algorithms of SOTDMA, providing a full flow for the realization of this algorithm. Finally, the paper induces the practical application of this technology, and raises an
integrated principle diagram of wireless user terminal networking based on SOTDMA.
We use our proposed discrete multi-resolution wavelet transform and grey system theory prediction to fuse sequence images to generate a high quality image. The fused images are simultaneously obtained via only one wavelet transform and the sequence of images. Several other methods were implemented to compare with the proposed approach. In fusion image, The sequence of images information can supplement each other, so the image fusion not only have abundant information, but also reserve the sequence of images detail. This experiment results also illuminates that image fusion is an important way to improve represent ability of image.