We redefine the unusual event detection problem from a different point of view. Several fundamental event features are investigated and adopted. These features are redescribed in a uniform model. Thus, using this model, supervised/unsupervised unusual event detection algorithms can be designed to fit various situations. Trajectory is treated as the most important feature. To more accurately measure the similarity of different moving object trajectories, a novel distance measurement, the sectional contextual edit distance (SCED), is developed. In the SCED, cost functions are designed according to contextual information and trajectories are segmented into subsections automatically, based on the relevant contexts. Velocity and orientation are also taken into account in cost functions to build an integrated distance similarity measurement. Experimental results demonstrate better performance using the newly proposed similarity measurement while being compared with the existing methods, and some cases of the unusual event detection problem are also demonstrated.
We present a novel and practical algorithm for the self-detection problem of contamination or occlusions on the lens of a camera mounted on a vehicle. First, we analyze the intrinsic characteristics of such contamination on the video image. Based on this, cumulative differences are used to segment the static region in the image. A blurred edge detection algorithm based on wavelet decomposition is introduced to confirm if the static region belongs to contamination or an occlusion. Through the combination of these algorithms, contamination or occlusions can be detected. Experimental data are analyzed to show the detection performance of our algorithm and the effect of different contamination or occlusion material.
A novel configuration for the transducer of magnetostrictive fiber-optic sensors was proposed and implemented. It is composed of a rectangle and two half-circles. The transducer with the novel configuration has not only higher sensitivity than that of traditional configurations, but good directivity. The magnetostriction was analyzed compared with that of cylindrical transducers. It is shown that the system sensitivity can be improved by increasing the long-side of rectangle and shortening the perimeters of the two half-circles.
Two transducers with cylindrical and racetrack configurations were fabricated. Moreover, an experimental setup to measure the low-intensity magnetic field detection responses was built up. Experimental results verified the analysis.
For its good directivity, three of them can be compounded as a vector magnetometer to measure three orthogonal components of magnetic field.
We study the optimization issues of ring networks employing novel parallel multi-granularity hierarchical OADMs. In particular, we attempt to minimize the number of control elements for the off-line case. We present an integer linear programming formulation to obtain the lower bound in optimization, and propose an efficient heuristic algorithm called Global Bandwidth Resource Assignment (GBRA) that is suitable for the design of large-scale OADM networks.
From element automatic control view, we propose a configuration algorithm for three-level cross-connects in data plane to handle with bypass, grooming and local add/drop traffic of fiber-level, band-level and wavelength-level by a abstract bipartite graph of MG-OXC and bandwidth utilization spectra graph. The configuration algorithm is evaluated by computer simulation as well as validated by experiment on our flexible Multi-functional Optical Switching Testbed (MOST).
To solve the scalability and flexibility issue in current optical network testbeds, a Multi-functional Optical Switching Testbed (MOST) has been built. Benefiting from design of modular hardware and layered software, network experiments of scalability and complicated node architecture can be made based on it. The hardware and software structure of the MOST system is explicitly analyzed in the article and demonstrations of a 12-node ASON and shared wavelength conversion ASON on MOST are also reported.
Many kinds of bulk hydrogen absorbing alloys undergo dramatic volume expansion when they absorb hydrogen. The maximum volume change varies with substances in the range of several to over twenty percents. Based on these phenomena, a new type of electrochemical microactuator has been designed. Bilayers of hydrogen absorbing alloy and nickel can generate a large bending and deliver high force, and it can work at very low voltage. As the first prototype, MmNi5 alloy film was chosen as the actuating medium, and it is deposited by sputtering method. The principle of this new microacturator and the microfabricating process of this bimorph are presented.
A novel electrochemical actuation based on the hydrogen aborbing-desorping of metal is presented. The hydrogen aborbing-desorping of metal was accompanying with the volume swelling and shrinking, which could be used to convert electrical energy into mechanical energy. This type of actuation not only has usual advantages of electrochemical actuation such as long travel distance and acoustical quiet, but also there was no the concerns of gas leakage of those electrochemical actuation driven by the gas pressure built up by electrolysis of an aqueous electrolyte solution. In this work, a mischmetal (Mm)-Ni based alloy film, MmNi5, was prepared by sputtering method. The MmNi5 film was studied by x-ray diffraction method (XRD) and electrochemical method. It was found that the metal film had undergone phase transformation during its hydrogen absorbing and desorbing cycle, which was first time to be observed for the metal hydride film prepared by sputtering method. The further results of surface micromaching and scanning electron microscope (SEM) indicated that the hydrogen-induced actuation was applicable in MEMS.
Optical switch is one of key supporting technologies in all-optical-network (AON) and electrostatic MEMS (Micro-Electro-Mechanical Systems) optical switch plays a very important role in the research of all-optical switch. The mechanics characteristics of the very thin beam and the micro-mirror in the structure of the electrostatic switch will influence the reliability and power consumption of the switch. In this paper, the relation between the sizes of the structure and the mechanics performance of the optical switch is discussed and simulated. In order to have high reliability, optimization designing of the beam and micro-mirror must be taken into account.
The comparison of Nickel electrodeposition in LIGA process with traditional electroplating by electrochemical methods was reported. The mass transport limitation during microelectroforming in LIGA was studied by linear potential sweep technique, the limiting current is easier to reach for plating into LIGA molds. The A.C. impedance measurement also supports the above viewpoint, beside this, it seems that the mechanism of electrode reaction also differ from that of conventional nickel plating. A semi-automatic electroforming equipment for LIGA process has been developed, various nickel microstructures with high aspect ratios have been fabricated in this equipment. a series of micro nickel gears have been fabricated, an advanced micro gear-box with 2mm diameter has been assembled, it works very well.