Applied Mechanics and Materials Vols. 128-129

Abstract: A fault testing device for the electronic instrument of certain type military equipment is developed in this paper. The PC104 bus, modular instrumentation and signal processing technology are integrated in the device. It consists of PC104 bus peripheral system, signal condition circuit, electric distribution cabinet, interface unit, connection cables and peripheral dedicated signal fixture. Based on Windows CE embedded operation system, the application program is implemented with Visual C++ programming language. The device could detect and locate the fault on replaceable unit of modular board and functional block, and could also assist serviceman and technical support personnel in performing quick fault testing and equipment maintenance.

Abstract: In this paper, a new method for determining the integrity of the image element of the target was proposed based on the self-made low-cost line structured light three-dimensional measurement platform, and BP neural network was used to complete the calibration of line structured light camera system. At the same time, Gaussian model for the four direction were constructed , which speeds up the extraction speed for the laser stripe center based on the gray gravity method of skeleton, and the point cloud data is deal with the refinement, noise removing, smoothing and three-dimensional reconstruction, which complete the task of product three-dimensional contour detection.

Abstract: This paper provides the state of the art in methods to detect damage in structural and mechanical systems by PZT sensors, which include impedance methods and lamb wave propagations. The basic idea behind these technologies is to use impedance of PZT embedded on surface or lamb wave propagations. A brief overview of research work on experimental and theoretical studies on various structures and mechanical systems is descried. Past, current and applications of this technology in actual engineering systems are summarized. Finally, desirable developments for further advancement of this field are discussed.

Abstract: As soon as the Intrusion Detection System (IDS) detects any suspicious or malicious activity, it will generate alarms. Unfortunately, the triggered alarms usually are accompanied with huge number of false alarms (false-positives and false-negatives) which is the key performance parameters of the IDS. The risk of false-negatives is higher than false-positives. In our previous paper, we proposed a novel intelligent intrusion detection, decision, response system (I2D2RS) with fuzzy theory, which use the two essential information times and time, of the failed login to decide automatically the attacker like an experienced system/security administrator. Though the system can reduce the false alarms perfectly, the capability of processing simultaneous multi-point attack is relatively weak, and then false-negatives will be occurred. In this paper, we employ a preprocessing module to collect the failed login information before data processing. The proposed approach changes the processing procedure from serial to parallel processing, thus eliminates the false-negatives. The efficiency of these improvements was confirmed with the experiments.

Abstract: Active sonar on small platform which uses vector array is selected in this paper as research object, the methods of signal and DOA estimation and the performance of these methods are discussed. Vector array comprehensive copy correlator and vector array comprehensive adaptive copy correlator which use acoustic pressure and vibration velocity at the same time are proposed in this paper. The performance of signal processing and the precision of DOA estimation can be improved by these methods. Simulation results present that the performance of the proposed methods are better than conventional copy correlator. In addition, vector array comprehensive adaptive copy correlator has higher gain than vector array comprehensive copy correlator in multi-path channel.

Abstract: Thin film sensor has the advantages of small size and low cost, which has become a research hotspot in recent years. A measurement system of passive optical fiber DC current sensor based on the thin film sensors is designed in this article. Designs of electric-heating converter, heating-light converter and low-voltage measurement display system are introduced in detail. Experimental results indicate that the general linear correlation between the time constant of fluorescent lifetime and the voltage across the thin film resistor. The feasibility of measurement system is verified via the results of the experiment.

Abstract: Characteristic information of FBG reflection spectra changes because of the existence of demodulation system error in the actual demodulation. The analysis of spectra for FBG under axial uniform force based on particle swarm optimization is given in this paper. Objective function is established and force experiments and numerical simulation of fiber Bragg grating have been made. The characteristic information of FBG reflection spectra under axial uniform force is extracted and theoretically reconstructed. The results show that, the improved particle swarm algorithm in fiber grating reflection spectra analysis is feasible. Also, the method has other characteristics such as high accuracy, good stability and fast convergence speed.

Abstract: Traditional measurement for geometric parameter of the irregular shape is considered as high cost and low efficiency, and large-scale automatic measurement cannot be achieved. In this paper, a low-cost, high-precision measurement system of irregular shape is presented. The system based on linear array CCD non-contact measurement method, in which a CCD camera is controlled to scan the projection of thread in the parallel optical field to acquire thread images. Meanwhile, an edge detection method based on gradient operator and linear fitting principle is proposed, the results show that the design improve the measurement precision efficiently.

Abstract: In order to solve the location problem of WSN, this paper uses MCL algorithm to follow location, and improve the limited appliance of MCL algorithm. Nodes in the direction of the MCL algorithm can greatly reduce the estimated location of speculation and location of the computational filter stage, saving the energy consumption of the node. And more easily filter out positions inconsistent with the observations. For the establishment of logistics tracking and scheduling planning service system to provide technical support.

Abstract: Operation and Operator are the key technologies in the new-generation geometrical product specification and verification (GPS). In order to solve the geometrical specification problems of product functional requirements and the ambiguity problems of product specification, this paper utilizes a new method based on dynamic description logic to describe the fundamental concepts of geometrical specification. It analyzes the geometrical features of geometrical product functional specification. By establishing the model of the operations, describing the input and output parameters in the specification and verification process, and analyzing the preconditions and results of the executions of specification operator and verification operator, the paper simplifies the operation results and overcomes the shortcomings of ambiguity and inconsistency in product specification process. Finally, it takes the specification process of perpendicularity as an example to prove the feasibility and validity of this method.