Showing papers by "Harbin Engineering University published in 2007"

Corpus-based HIT-MW database for offline recognition of general-purpose Chinese handwritten text

Abstract: A Chinese handwriting database named HIT-MW is presented to facilitate the offline Chinese handwritten text recognition. Both the writers and the texts for handcopying are carefully sampled with a systematic scheme. To collect naturally written handwriting, forms are distributed by postal mail or middleman instead of face to face. The current version of HIT-MW includes 853 forms and 186,444 characters that are produced under an unconstrained condition without preprinted character boxes. The statistics show that the database has an excellent representation of the real handwriting. Many new applications concerning real handwriting recognition can be supported by the database.

Photoresponse of SnO2 nanobelts grown in situ on interdigital electrodes

Abstract: The photoresponses of SnO2 nanobelts grown in situ among interdigital electrodes on silicon substrates were investigated under ultraviolet (UV) light and green laser illumination. The current increased to ~140?nA in vacuum under green laser irradiation with a power of 35.1?mW. Under UV illumination, however, the source?drain current increased to ~80??A in air and up to ~900??A in vacuum, respectively. The UV photoresponse was a result of electron transition from the valence band to the conduction band, while the green laser photoresponse was dependent on oxygen pressure, ambient temperature and defect levels.

Comparison of Unscented Kalman Filters

Abstract: Unscented Kalman filter (UKF) has been proven to be a superior alternative to the extended Kalman filter (EKF) when solving the nonlinear system in previous literatures. In order to accelerate the application of UKF in the actual system, a new simplified UKF is proposed in this paper. It is called Rao-Blackwellised additive unscented Kalman filter (RBAUKF), and is specially designed for the dynamic system with the additive noise, the nonlinear state equation and the linear measurement equation. Furthermore, three kinds of UKF are introduced at the same time for the purpose of comparing their advantage and disadvantage. The three filters are general UKF, additive unscented Kalman filter (AUKF), and Rao-Blackwellised unscented Kalman filter (RBUKF). In fact, the AUKF and RBUKF are the improved filters of the general UKF, and RBAUKF proposed in this paper is the upgraded version, which synthesizes the feature of AUKF and RBUKF. Finally, the simulation and analysis of the above UKF algorithms are done. The simulation results indicate that the computational complexity of RBAUKF is nearly half of UKF. The computational complexities of AUKF and RBUKF are in between UKF and RBAUKF. Moreover, the estimation accuracies of RBAUKF, AUKF and RBUKF are the same, while that of UKF is lower than theirs. It suggests that the performance of RBAUKF is best following by AUKF and RBUKF, and it is better than the general UKF.

Shape memory effects of poly(L-lactide) and its copolymer with poly(ε-caprolactone)

Abstract: The thermal properties, crystalline structure and shape memory effects of poly(L-lactide) (PLLA) and its copolymer with poly(e-caprolactone) (PCL) are systematically investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and tensile tests. The influences of composition and intrinsic viscosity on structure and shape memory effects are also revealed. It is found that the PLLA homopolymer and poly(L-lactide-co-e-caprolactone) (PCLA) copolymers exhibit good shape memory effects. The existence of PLLA crystal and amorphous phase play very important roles for shape memory effects. The intrinsic viscosity obviously affects the crystallinity of polymers and further affects the shape memory effects. The shape recovery rate decreases with increasing deformation strain, which is relate to the deformation of PLLA crystal. The recovery stress increase with the increase of the e-CL content and maximum recovery stress is 3.54MPa obtained in the PCLA804 (20wt% e-CL content, Mw=304,400). With the increase of cyclic testing number, the shape recovery rates decrease and the shape retention rates increase at the beginning and then approach to a steady value.

Collision Avoidance in Multi-Robot Systems

Abstract: Multi-robot systems have been widely applied to various applications to perform a given task collaboratively and cooperatively. In a multi-robot environment, path-planning or collision avoidance is an important problem. This paper tackles this important but challenging problem. We developed a step-forward approach for collision avoidance in multi-robot systems, building on the established techniques from omni-directional vision systems, automatic control, and dynamic programming. The developed collision avoidance algorithms can help avoid the collision from any static obstacles and any dynamic objects such as a moving robot. In this paper, we report the developed collision avoidance algorithms, along with simulation-based experimental results. The results show that the collision avoidance strategies are effective and useful for making decisions on collision avoidance in multi-robot systems.

Object Tracking Algorithm Based on Camshift Algorithm Combinating with Difference in Frame

Abstract: Object tracking algorithm based on Camshift algorithm which is combinating with difference in frame is put forward to quickly and exactly track movement object. Firstly, we confirm the movement region of object by difference in frame, and we again confirm centroid of movement region which is centered to initialize tracking curve. Secondly, the feature is abstracted in the region and the target is tracked by Camshift algorithm. The method overcomes shortcoming of artificial orientation and divergence problem for traditional Camshift during tracking. We prove the validity of the algorithm by experiment at last.

Artificial immune system inspired behavior-based anti-spam filter

Abstract: This paper proposes a novel behavior-based anti-spam technology for email service based on an artificial immune-inspired clustering algorithm. The suggested method is capable of continuously delivering the most relevant spam emails from the collection of all spam emails that are reported by the members of the network. Mail servers could implement the anti-spam technology by using the “black lists” that have been already recognized. Two main concepts are introduced, which defines the behavior-based characteristics of spam and to continuously identify the similar groups of spam when processing the spam streams. Experiment results using real-world datasets reveal that the proposed technology is reliable, efficient and scalable. Since no single technology can achieve one hundred percent spam detection with zero false positives, the proposed method may be used in conjunction with other filtering systems to minimize errors.

A New Jellyfish Type of Underwater Microrobot

Abstract: In the medical field and industry application, fishlike microrobot and micro biped robot with multi DOF that can swim smoothly in water or aqueous medium has urgently been demanded. And IPMC (ionic polymer metal composite) can generate large bending motions under a low driving voltage (about 1 V), and it has a good response and soft characteristic. In this paper, we have developed a new jellyfish type of microrobot which can imitate the jellyfish. It has a movement process as the jellyfish does when it is floating and sinking. The process of floating and sinking can be controlled. Four legs using IPMC actuators are designed to replace the antennae of the jellyfish. Characteristic of the underwater microrobot is measured. Some improvement has been done for higher efficiency. The experimental results indicate that the moving and swimming speed of underwater microrobot can be controlled by changing the frequency of input voltage.

A centimeter-scale autonomous robotic fish actuated by IPMC actuator

Abstract: This paper presents the research toward centimetre-scale autonomous robotic fish mimicking a kind of goldfish. The robotic fish is propelled by an iconic polymer-metal composite (IPMC) actuator and equipped with a microcontroller and an infrared sensor for wireless control, autonomous navigation and obstacle avoidance. To improve turning ability of the robotic fish, we set the length of caudal fin and the flexible part to half of the whole length. The overall size of the robotic fish is 98 mm in length, 30 mm in width, and 22 mm in thickness. The weight of the robotic fish is 21.9g. The obstacle avoidance method, remote control and turning mechanism of the robotic fish are described respectively in this paper. The experimental results show that the structure of the robotic fish and its avoidance function, remote control and turning method are feasible. In centimetre-scale autonomous robotic fish driven by IPMC actuator, the obstacle avoidance function makes our robotic fish smarter. With the help of this robotic fish we can do some low speed and high maneuver tasks in limited space easily.