Applied Mechanics and Materials Vol. 742

Abstract: In this paper, we report a dual-wavelength temperature sensor based on fiber optic delay. This temperature sensor don’t need to rely on accurate spectrum measurement, but to realize temperature measurement by detecting the variation of delay, which can efficiently reduce the cost and complexity of sensor system. In this dual-wavelength system, one wavelength of light is used as a reference and the other one is used for temperature sensing, so this design can effectively eliminate the negative influences of unstable external environment. The principle of this temperature sensor is theoretically derived, the schematic of sensor system is analyzed and the feasibility of this method is tested in the temperature range of 0°C-80°C. Results indicate that, this temperature sensor is able to achieve temperature measurement in a simple way with low cost.

Abstract: Data aggregation is an important techniques to save energy consumption in wireless sensor networks. However, the compromised aggregators may forge fake values as the aggregated results of their child nodes. In this paper, we proposed an efficient secure data aggregation scheme to overcome the problem. Integrated with the privacy homomorphism and the aggregate message authentication code techniques, our proposal can provide both end-to-end privacy and data integrity in data aggregation for sensor networks. The performance analysis shows that compared with other existing secure data aggregation schemes, the proposed scheme has remarkable advantages in terms of computation and communication overhead.

Abstract: An ultrasonic Rayleigh wave transducer was designed for nondestructive pressure measurement in vessels. Using polyimide resin as the wedge material, the Rayleigh wave transducer had two piezoelectric elements which were placed in the same wedge with a certain distance. Variations in pressure and temperature of vessels can affect the velocity of ultrasonic waves, which will affect variations in time delay in receiving of the same Rayleigh wave with the two piezoelectric elements of the designed transducer. Based on the acoustoelasticity principle and considered the effect of temperature, a practical correlation model between the time delay and both the pressure and temperature of vessels was developed. Using an air vessel as a specimen, Rayleigh wave transducers were arranged in the axial direction of the vessel. The results of temperature experiments show that effect of changes in temperature on time delay agree with the theoretical results. With the calculation temperature compensation in pressure experiment, the relationship between the variations in the time delay caused by changes of pressure and the pressure is established. The pressure measurement results show that the measurement model is effective and the maximum absolute error is 0.09 MPa, which could be acceptable in engineering application.

Abstract: As part of studies into the use of Smartphones as solar-radiation monitors, this article characterizes the violet response of a consumer complementary metal oxide semiconductor (CMOS)-based Smartphone image sensor in a controlled laboratory environment, with an adjustable Lamp as a radiation source, a band-pass filter (central wavelength is 400nm) covered on Smartphone camera lens and a ASD spectrometer observing synchronously. It is found that a logarithmic relationship appears between CMOS-based sensor imaging DN values and irradiance, and the red (R) component in the chromo-photograph is linearly relative to irradiance. In addition, a Smartphone can be used as a convenient and low-cost scientific instrument in the field of monitoring radiation characterization, due to its capacity to detect usable irradiances.

Abstract: Based on the fundamental principle of magnetic compass, the effect of interference and sensor errors on the magnetic azimuth measurement accuracy are analyzed. In order to eliminate the influence of geomagnetic sensor system error interference sources effectively, the paper puts forward a method of obtaining accurate heading angle and azimuth of magnetic compass, which is realized by converting magnetic components in the space coordinates to horizontal coordinate as well as adding an algorithm of eliminating carrier interference and software filter. The test of application system shows that data errors are greatly reduced after adding the anti-interference algorithm. The system testing errors is almost equal with Xiaomi phone at the same condition. It proves that this system is applicable to general navigation field.

Abstract: Firefly-inspired synchronicity method using reackback response is effective with existence of message delay. We introduce a weighted factor based on RSSI into the phase increment calculation. Besides, different coupling strength parameters are selected according to the degree of synchronicity to achieve a good balance between synchronicity speed and accuracy. Simulink module is constructed and the results prove that this method shows great resistance against random variation of the message delay within an acceptable range.

Abstract: We use quartz crystal material from a physical point of constitutive equations derived in detail combined with the boundary conditions of the liquid Kanasawa QCM response model and Martin correction BVD equivalent circuit model; then apply transmission line theory and the theory of Acoustic impedance load, the research results can be useful as a QCM-D model, response model and Martin mode, then in-depth analysis of the liquid phase conditions, factors affecting the QCM frequency change, we propose a new method for measuring the density of the unknown liquid viscosity supplement. The main purpose of this chapter is to illustrate the viscous liquid medium under contact conditions, based on transmission line theory and the theory of load Acoustic impedance method compared to the classical method is simple, accurate, and effective.

Abstract: The eddy current sensor can be used to measure the displacement. It is widely used in petrifaction, electric power, mechanism. The eddy current sensor has fast dynamic response, non-contact measurement, and better adaptability characters. The accuracy of eddy current sensor often is influenced by the environment temperature. The environment temperature effect is analyzed and put forward to a method to compensate to enhance the accuracy.

Abstract: Through the analysis of two-position sampling data based on the maglev gyroscope north seeking theoretical model and the verification of north seeking experiments results via several aspects, it was found that there were systematic deviations between the maglev gyroscope north seeking process and the theoretical model. It’s mainly reflected in the deviation of the trend term deviation and constant deviation related to the north seeking erection orientation. They don’t impact the stability of north seeking according to our analysis. The constant deviation impact the absolute north seeking accuracy, but it can be offset by data differential. Finally, the author believe that the maglev gyroscope north seeking data characteristics can be used as priori conditions of data filtering and elimination of gross error. It can also be used in the assessing precision of the gyroscope orientation.