Applied Mechanics and Materials Vols. 475-476

Abstract: Energy management is critically important for sensor networks for the PM pollutant due to the requirements of long-term observations for the sake of accuracy. In this paper, an energy saving scheme, basing on the temporal distribution characteristics of PM pollutants, is proposed. The reliability as well as efficiency of the proposed scheme is validated by experiments and theoretical analysis.

Abstract: This research proposes a novel piezoelectric harvester structure which is constructed by a cantilever base beam and piezoelectric elements bonded with the base beam in a certain manner. By changing the electrical boundary conditions of the piezoelectric elements, the resonant frequency of the beam structure changes accordingly. Two kinds of manners in which piezoelectric elements are bonded with the beam are investigated and compared with ANSYS simulations and experiments. The results showed that the embedded manner surpasses the surface-bonded manner with the frequency variation ratio of 3.17%.

Abstract: Based on the summary of Wireless Sensor Networks' characteristics, we analyze the Wireless Sensor Networks' applications and its development trends, and put forward the factors that restrict the development of Wireless Sensor Networks. In this paper, we analyze the Wireless Sensor Networks development opportunities and challenges in the future, and provide some new ideas and enlightenment for the comprehensive development and widely used.

Abstract: The construction of Electronic Nose system and associated signal processing methods were introduced .Then special references to applications to dairy products, such as the classification of different milk, the milk with different shelf-lives, flavor quality evaluation, antibiotics resedues detection and quality control were discussed. The results show that the quality of dairy products can be evaluated effectively using Electronic Nose system. The development trends of Electronic Nose are presented.

Abstract: Virtual Instrument as the fifth-generation instrument has been a new technology with its unique advantages and got applying and developing more and more widely. From the view of composition and characteristics of the virtual instrument, the paper expounds the designing and developing process of electric field sensor calibration system based on the Ethernet and GPIB communication protocols. The table of the electric field sensor calibration system developed in the paper with a friendly interface improves the work efficiency of the electric field sensor calibration greatly, and the method and process of developing the electric field sensor calibration system could be a reference for the development of other relevant virtual instruments.

Abstract: According to the architecture feature of the fault tolerant sensor system, a hierarchical combination reliability modeling method was proposed based on the dynamic fault tree analysis and the Markov process. Temporal operators were applied to represent the sequential logic, and the analytic formula for the failure probability of the top event was derived. The FDI (failure detection and isolation) behavior was modeled by the Markov process. The resultant model was compared to the PFCM (perfect fault coverage model). The impact of the parameters on the system reliability was evaluated. The simulation results demonstrate the modeling method is feasible, efficient and more accurate.

Abstract: For the selenium content on-line detection of low voltage electrophoresis chip-atomic fluorescence, a design scheme of carrier gas flow velocity and flow direction sensor, which is fabricated using MEMS technology, is presented. A new structure was designed to achieve the current detection of heater, the detection of temperature and the discrimination of flow direction. Cu layer of the flexible PCB was used as resistive material because of its stable physical properties and linearity of temperature to resistance conversion. The sensor consists of one copper current detector, two copper flow direction detectors, one double-spiral copper micro-heater and one copper temperature detector. The operating principles and the fabrication of carrier gas flow velocity and flow direction sensor is emphatically expounded. Simultaneously, the detection and control system of carrier gas flow velocity and flow direction sensor and its interface circuit are analyzed and discussed.

Abstract: A template technology has been applied to the platform of machine olfaction. The simulation sensor array template receives field odor data or simulates the data via recorders in database, and transmits to the platform. The platform consists of several distributed monitoring subsystems based on the simulation template. Each subsystem matches a set of gas sensors array, and has functions of logging data, communicating and simulating industry application. The data from the subsystem and the preprocessed data are sent to the web server center and stored in the databases. The data has been collected, and sensor performance analyzing are performed by several layer algorithms. While the exchanging algorithms convert the field odor data to gas concentrations with ppm values, the expert systems or recognition algorithms analyze the ppm values and show the application results. All data of each layer are stored in server database systems, and each layer algorithms can been updated and saved. Finally, the supporting platform that applied to industrial monitoring systems, was developed with a kind of industrial configuration softwares, web MIS and databases, and was utilized to realize monitor to the environmental systems by the simulation template.

Abstract: A second order delta-sigma analog-to-digital converter (ADC) including a bandgap reference, a bias circuit for sensor, and a digital filter for the interface of piezoresistive pressure sensor is presented. The proposed sensor interface circuit is designed to target a pressure range from 0 to 100 psi. The prototype sensor interface circuit is implemented in a 0.35 μm CMOS process. The single-loop, 1-bit, second-order delta-sigma ADC operates at OSR of 256 achieves 80.5 dB dynamic range (DR), 79.6 dB peak signal-to-noise ratio (SNR), and 74.4 dB peak signal-to-noise and distortion ratio (SNDR) over a signal bandwidth of 7.8 kHz with 3.3V supply while consuming 0.33mW including on-chip reference and bias current for sensor. (in Performance Summary: 0.95mW)

Abstract: Using piezoelectric sensors and low noise power amplifier, a probe for leak location was designed. With A/D-D/A converter TLV320AIC10s and one DSP chip TMS320C5402 which received the sampled data through McBSP0, the hardware connection of the two way real time sampling and correlation analyzing system for audio signals was accomplished. The software program of the system was completed by using assembly language in conjunction with C code. The experiment results indicate that the system is reliable and practical.