Applied Mechanics and Materials Vols. 241-244

Abstract: Laser differential confocal sensor (LDCS) is a high precision and high integrated measurement system. In order to meet the demand of the LDCS, a novel implementation method of high precision conditioning circuit is studied. This circuit consists of photoelectric conversion, secondary amplification and signal operation. The photoelectric conversion is designed to detect the light intensity signal and transform it into a voltage signal. In order to adapt the test for different samples, the magnification is adjustable in secondary amplification unit. The two-way light intensity signals of the LDCS are differentially subtracted in signal operation unit. The noise characteristics of the photoelectric conversion unit were analyzed and the methods for decreasing noise were presented. The experimental results show that signal to noise ratio (SNR) of the conditioning circuit is better than 1160 and the sensitivity of LDCS reaches 2.168V/μm, which has the advantages of low noise, high stability and high integration and can widely used in many kinds of high precision photoelectric measurement systems.

Abstract: Air-fuel ratio, a major parameter of petrol engineer, directly affects the power, economy and indicators of exhaust emission of engine. To make the air-fuel ratio in the best state, the air flow entering into cylinder must be measured accurately. Due to gaseous property of air itself, the flow detection is greatly interfered by temperature and pressure. In the article, we used surface acoustic wave(SAW) technique combined with temperature and pressure compensation and made a detection device for engine intake, which was less interfered by temperature and pressure with high accuracy and wide measuring range. The paper introduced the working principle of SAW air flow sensor and its mathematic model, and discussed the development, signal detection and error processing of sensor. The results showed that SAW sensor could better overcome the interference of temperature and pressure, and then accurately got the air flow value of engine with preferable repeatability and reliability.

Abstract: The electrical properties of nonconductive polyaniline (PANI) films exposed to gamma radiation for the purpose of gamma dosimeter were presented in this work. By exposing films to doses of gamma radiation up to 10 kGy, the films showed visually apparent gradual change in the current- voltage (I-V) characteristics. Electrical, conductivity also increased regularly in the same dose range. It can be suggested that gamma radiation dose has an effect on transformation of polyaniline in its nonconductive form to polyaniline in its conductive form (PANI-HCl) which may be used for dosimeter in a gamma doses up to 10 KGy.

Abstract: The work presented in this paper focuses on the output of temperature compensation system of diesel engine piezoresistive pressure transducer, it is nonlinear and influenced easily by environmental temperature. The paper studied the method of using improved neural network algorithm based on LabVIEW and MATLAB to increase the precision and efficiency of pressure detection. In order to eliminate the temperature influence, this paper proposed the method of using improved back propagation neural network on LabVIEW platform, which realized the communication between LabVIEW and MATLAB. The experimental results show that, with the using of Matlab Script node, the system benefits from the huge computing power of MATLAB to train the network based on the static calibration data of transducer, and makes temperature compensation more efficient and accurate.

Abstract: Energy consumption phenomenon has always been noticed in sink-based wireless sensor networks. This paper explored an energy efficient routing protocol with a mobile sink based on the shortest path data transmission mode. According to the position of the sink node and the common nodes' ID in the network, we calculated the coordinate value of each node in the network. By comparing the coordinate values to choose the shortest path to forward the data. Simulation results show that this method can prolong the lifetime of the network and improve the energy utilization ratio of nodes.

Abstract: Micro-resonators could be fabricated directly on the optical fiber top by micro mechanical process. The micro optical fiber resonator has more great advantages comparing with the traditional optical excited micro silicon resonators, such as being optically positioned easily between the resonator and the optical fiber end. By this way, the optical excited light through the fiber core is thus put on the micro resonator accurately and then partially reflected by the Fabry-Perot interferometer formed between fiber top and resonator surface. The reflected light from F-P interferometer was sent to the opto-electric detector PIN to demodulate the detected parameter. A matched metal layer can be deposited atop of the resonator in order to increase the optical excitation efficiency. Firstly mechanism analysis of optical excited bi-layered resonator is given by fully considering Longitudinal thermal strain effect and Bi-coating effect, and then the typical theoretical models were setup including the resonating frequency and resonant amplitude, and temperature sensing feature was simulated by computer software. The simulation results indicated that the average frequency sensitivity of temperature sensing is about 29Hz/°C.

Abstract: In view of the coupling relationship between the Zernike modes over the concentric circle domain within the unit circle and the wavefront counteraction of those coupling modes within the reconstruction pupil region, the linear combination models of Zernike modes are presented. The modes in each model share with negative correlation, same coefficient sign and prescribed amount. Finally, the experiments are implemented on AO system, the results show that it’s feasible and advantageous to use the combination models in the process of aberration correction.

Abstract: A method for detection of sulfamethazine（SMT）in milk by coupling indirect inhibition assay with a self-assembled monolayer was developed. The method of immobilization of SMT-BSA on the chip surface was also introuduced. A series of milk samples with spiked 0, 5, 10, 20, 30, 40 ng/mL of SMT were analyzed by the SPR biosensor and the standard calibration curve of SMT in milk was constructed. The intra-assay relative standard deviation (RSD) and recovery were 6.3% and 102.8%, respectively. The inter-assay deviation (7 days) was less than 6 IU, and demonstrated the method’s stability. The high stability of the SPR sensor underlies the potential of the SPR method as a stable and high-precision tool for detection of SMT.

Abstract: According to the requirements and characteristics of the long-span bridge vibration monitoring, this paper presents one kind of low-frequency wireless accelerometer monitoring system based on PIC and MEMS (Micro-electromechanical Systems) acceleration sensor. The system was composed of sensor module, data acquisition and processing module, micro-processing module, wireless transmitting and receiving module, and a computer system. Model 1221 was the sensor chip, the measure data processed by MCU, and transmitted by wireless transmitting module based on Zigbee networks. As the date was received by the wireless receiving module, re process the sensing data by computer, to get the vibration parameter and assess the vibration. The system was validated with standard vibrator.

Abstract: Strain measurement in electromagnetic rail launching processes is of significant importance to studies on rail life, wrap material selection, and initial armature disturbance. Based on a discussion about the principle of fiber-optic differential strain measurement, the constitution of a rail strain measurement device based on fiber-optic differential interference was introduced, and its data processing method and system calibration method were discussed. With this measurement method, electromagnetic rail strain measurement was completed, and experimental results indicate that the differential strain measurement device is able to operate reliably and stably under an intense electromagnetic interference environment in an electromagnetic railgun launching process and can be applied to strain measurement and in-bore projectile motion velocity measurement of gun barrel weapons.