Applied Mechanics and Materials Vols. 738-739

Abstract: Trouble-free operation of large-scale mechanical equipment is of great significance to modern industrial production. The existing wireless sensor network nodes are not suitable for condition monitoring of mechanical equipment due to their low acquisition accuracy. In view of this, this article put forward a wireless sensor network for mechanical condition monitoring, and designed corresponding wireless sensor network nodes. These nodes could achieve high-precision acquisition of analog signals. This article described a wireless sensor network structure for mechanical condition monitoring, hardware design of wireless sensor nodes and software design of the system. The precision of the wireless sensor network nodes we designed was verified by experiment. The experiment result showed that the nodes could effectively acquire analog signal with high precision.

Abstract: Due to its high position resolution and fast speed, the position sensitive detector (PSD) is widely applied in micro displacement measurement. However, almost all PSDs suffer from high nonlinearity. In this paper, three kinds of PSDs and their advantages and disadvantages are introduced. Then principle of pin-cushion PSD is studied, based on which a new signal processing system is designed. The signal processing system consists of a high-precision sensor circuit and a software system integrated with a correction algorithm. The test result shows the linearity of the PSD is greatly improved.

Abstract: Large wear debris is an important indication of abnormal wear of aviation engines. Analysis of the relationship between particle parameters and the output signal plays an important role to improve the sensor sensitivity. A three-coil simulating sensor model is constructed using APDL finite element program. After analyzing the influence factors to the induced output voltage of the sensor, such as debris material, location, size, exciting current etc, the fitting characteristic curves are obtained, realizing the quantitative analysis. Simulation results show that the sensor model can effectively distinguish between conductive and non conductive, ferromagnetic and non ferromagnetic debris. The induced voltage can reach 10^-4 V for the 500 microns ferromagnetic abrasive particles. The characteristic curves provide important basis for further research on sensor structure optimization.

Abstract: This paper presents millimeter wave characterization and models of various wire bond transitions between chip’s ground-signal-ground pad (GSG) and microstrip (MS), include single-wire-nomatch MS-GSG transition, double-wire-nomatch MS-GSG, single-wire-match MS-GSG transition, and double-wire-match MS-GSG transition. It also presents the 3D full-wave electromagnetic simulation. Analysis results show that the double-wire-match MS-GSG transition’s characteristic is better than other three transitions in the whole W band. The accurate extracted parameter values are used for the lumped equivalent circuit model, whose simulation results are good with the full wave simulation results. The error between lumped equivalent circuit and full-wave models is of the order of ±0.2dB for S11 and S21 in the frequency range 75 - 105GHz. The proposed lumped equivalent circuit is suitable to be implemented in commercial microwave CAD tools for the electromagnetic sensor designing.

Abstract: A Wireless Sensor Network is composed of sensor nodes powered by batteries. Thus, power consumption is the major challenge. In spite of so many research works discussing this issue from the aspects of network optimization and system design, so far not so many focus on optimizing power consumption of the Radio Frequency device, which consumes most of the energy. This paper describes the digital features of the Radio Frequency device used to optimize current consumption, and presents a practical approach to measure current consumption in static and dynamic scenarios in details, by which we evaluates the power saving effect. The results demonstrated that according to cycle times and application characteristics choosing appropriate features can prolong the lifetime of wireless sensor nodes.

Abstract: Rapid-response biosensing systems are necessary to counteract threats due to high-consequence pathogens. A disposable immunosensor suitable for quantitative determination of E.coli O157:H7 in pure cultures was investigated by electrochemical impedance spectroscopy (EIS). Electric responses of this biosensor for different cell concentrations at multi-frequencies were explored utilizing disposable screen-printed silver four-wire interdigitated microelectrodes (IMEs). Additionally, the best response frequency for the detection was studied, and the relationship between the impedance at this frequency and the concentrations of E.coli O157:H7 was established. The results showed that the impedance biosensor showed linearity from 1.15×10³ CFU/mL to 1.15×10⁶ CFU/mL at 100Hz, which yielded the model coefficient to 0.951.

Abstract: This paper describe the principle and constitution of electronic nose. Then the examples of application on testing the quality of agriculture products are presented also. The future development trends of electronic nose are evaluated at last.

Abstract: SAW sensing technology has advantages of wireless, passive, small size, low cost, fast response, strong anti-electromagnetic radiation, measurable for moving or rotating objects, tolerable for wet dirty or high temperature and other harsh environments. Comparing with the traditional sensing methods, the test of SAW sensing technology can cover almost all the needs of digital substation internet of things.

Abstract: It is necessary for hearing-impaired children after hearing compensation for language rehabilitation, Rehabilitation evaluation system can timely understanding of the effect of rehabilitation, rehabilitation program reasonable.This paper presents multiple feedback method and system for hearing-impaired children pronunciation evaluation based on 3D technology, information technology, the use of modern means of measuring real-time speech. The evaluation system collect the tongue palate, lip face and voice pronunciation information of hearing-impaired children through sensor and voice input devices.The reference value to compare the data with the standard output,The system can overcome the shortcomings of traditional method is subjective.To assess abnormal and the degree of abnormal of hearing-impaired children s function. Provide the basis for the development of language rehabilitation training plan, establish a scientific evaluation method and evaluation system.

Abstract: As a novel technology of information acquisition and processing, Wireless Sensor Network (WSN) has been widely used for complex large-scale localization tasks. With global distribution and sensing ability, wireless sensor network can provide valid optimal localization for mobile targets. According to the key problems of mobile target localization under wireless sensor network, this paper depicted current research status in both of line-of-sight and non-line-of-sight environments. Typical and representative algorithms are sorted and their ideas are evaluated. Finally, we discussed and anticipated the future research direction.