Applied Mechanics and Materials Vols. 530-531

Abstract: Security measures could not absolutely prevent network intrusion. The security technology of intrusion detection system had made up for the lack of preventive measures; it could provide real-time intrusion detection and take appropriate protection for network. The research directions of WSN security were how to improve security strength and prolong the life of nodes, how to enhance the preventive ability of intelligent security system and real-time detection with high detection accuracy. This paper analyzed the typical network intrusion and defensive strategies, and researched WSN intrusion detection model by analyzing the typical algorithm. IDS model was divided into three types the first was based on single-node detection, the other was based on Multi-node peer cooperative, and the third was based on task decomposition level. Finally the paper gave the main research topic and direction for WSN security issues.

Abstract: Measuring circuit and equivalent circuit of piezoelectric sensor and its parameters of voltage, capacitance and charge are analyzed. The intensity, the sensitivity and natural frequency of pressure sensor are designed. The influence factors and compensation method of pressure sensor nonlinear such as effective area of diaphragm, pre-tightening force, and temperature are analyzed. Key words: Sensor; Piezoelectric wafer; Measure circuit; Equivalent circuit; Nonlinear

Abstract: This research is focused on the synthesis of a polystiren layer for biosensors based on a Quartz Crystal Microbalance sensor (QCM) to immobilize the biomolecule. The polystyrene thin film was deposited by means of spin coating method with various solvents, such as chloroform, toluene, xylene, and tetrahydrofuran (THF), containing a 3% polystyrene solution by mass. The morphologies of the polystyrene layers were observed via SEM/EDx. The polystyrene surface coated using chloroform as the solvent has a rougher morphology and the largest diameter pores compared with the other solvents. The result show the polystyrene surface coating produced with chloroform caused a higher frequency change, which resulted in the binding of a wider range of biomolecules.

Abstract: Considering the detection of pavement moisture content not currently specialized sensor, this paper has studied the dielectric sensor based on FDR working principles, properties and condition. The dielectric sensor based on FDR was used for the exploratory study pavement structures and brief description the embedding method and technical requirements. The dielectric sensor based on FDR readings law was summarized by a variety of materials and field calibration method, the dielectric sensor based on FDR being used for field calibration method and data processing method was mastered first-hand data, and the detection of pavement moisture content was resolved preliminarily as the foundation for subsequent problems relating to studying in this paper.

Abstract: Sensor is the core component of structural health monitoring system, which can collect the data of structural damage. The structural damage state can be gained after further processing. Aircraft serves in rigorous environment, and existing sensors cant meet the demand of its structural damage monitoring for inherent defect. A preparation method of partial poling piezoelectric film sensor was proposed in the paper, which can be used for structural damage monitoring of aircraft in combination with lamb wave.

Abstract: In this paper, a novel large-strain sensor based on a dual planar capacitive structure has been developed. It has the capacity of large-strain measurement up to 200,000 με (0.2 ε). The change in strain causes a measurable transformation in the capacitance of the sensor by relative shift of the overlap area between two capacitive plates, one fixed (i.e. fixed plate) and the other one movable (i.e. movable plate), and is thus converted into a voltage signal by a read-out circuit module. The dual capacitor structure was designed for increasing the initial capacitance and improving the resolution of sensors compared with a single capacitor structure. The experimental results showed that the sensor had a linearity of 2.29% full scale (FS), a hysteresis error of 1.146%FS, repeatability of 0.226%FS and a resolution of 0.5%FS, suggesting excellent performance of the sensor.

Abstract: Magnetic guidance drilling technology is use of magnetic guidance instrument measuring the distance between the signal source and the location of the instrument, and it is used to control the well trajectory to connect or parallel the target layer. And it is an effective supplement of the existing steering drilling technology. At present, the magnetic guidance drilling technology is mainly applied to drill horizontal wells in pairs for the super heavy recovery, CBM horizontal connected wells, underground soluble minerals, relief well and so on. This paper introduces the research process of the magnetic guidance prototype.

Abstract: This system consists of a pressure silicon sensor, calibration module and wireless module. The pressure sensor used in this work is a piezoresistive silicon sensor that developed by Technical University Berlin. After calibration of the sensors output signals, the XBee-chip was used for wireless transmission. The three components with peripheral circuits and batteries were integrated in a 50mm × 50mm PCB. The system was then tested in a climate chamber at different temperatures and pressures. Programs for signal receiving and processing were developed in Matlab-environment. The experimental results show that this system works well for the short range (15m indoor).

Abstract: This paper presents the design, fabrication and characterization of quartz tuning fork temperature sensor which is based on new ZY-cut-quartz crystal bulk acoustic wave resonator vibrating in a flexural mode. Design and performance analysis of the quartz tuning fork temperature sensor has been conducted and the thermal sensing characteristics were examined by measuring the resonance frequency shift of this sensor cause by an external temperature. The sensor prototype was successfully fabricated and calibrated from operating from 0°C to 100°C with sensitivity of 70ppm/°C. Experimental results show the sensor has high thermal sensitivity, good stability and well reproducibility. This work represents high precision and low power temperature sensor using the comprehensive thermal characterization of ZY-cut-quartz tuning fork resonator.

Abstract: This paper presents a new type metal detector measurement system based on linear Hall-effect elements. This system adopts a low voltage DC power supply, which drives a U type (or C type) core coil to generate a magnetic field space. Two linear Hall-effect elements are placed at the center of core coil measurement section. With the differential operational testing method, the sensing signal is collected and displayed with SCM system. In the paper, we analyze the feasibility of the measurement system in theory. Further a practical measurement device is designed and produced to verify the theoretical analysis. Experiments data shows that, within a sensing gap between 0.5mm and 3mm, this new Hall-effect element metal detection equipment could effectively resolute nondestructive metal and the damage metal with small cracks, especially sensitive to the longitudinal crack. As a conclusion, this metal detector has several advantages such as simple structure, small volume, low cost, no radiation, so that it would be convenient for production, carrying and application. The new type metal detector measurement system proposed in this paper has important significance for industrial and manufacturing production testing and maintenance of equipment.