Applied Mechanics and Materials Vols. 475-476

Abstract: In this paper, an air quality monitoring system based on sensor array and framework of cloud computing is implemented. This system can surveil and report the information gathered from the ambient air condition in real time and inexpensive way, it can protect the public's right to know about the environmental security that everyone living in. All efforts and works of this paper is to turn the dreams into reality: to preserve and improve the quality of our living environment's air, in the sense of keep the damage to our health far away, through the strong pressure of public opinion.

Abstract: To improve efficiency and automation of the 3D full-field surface strain measurement for sheet metal forming, a new grid strain measuring scheme was developed based on the close-range photogrammetry technology. A Local Canny Detector algorithm was proposed for grid nodes and coded targets detection. A 10-parameters nonlinear camera model and the bundle adjustment algorithm were used to optimize the calibration parameters. A multi-epipolar constraint method was employed for grid node matching. Finally, the surface strains were calculated according to the changes of the grid sizes. To evaluate the performance of the proposed scheme, a stamping forming experiment was conducted. Experimental results show that the scheme can provide a non-contact, intuitive and effective solution for strain measurement in sheet metal forming process.

Abstract: Fault dictionary is the most practical method of fault diagnosis in analog circuit. Before analog circuit with tolerance is diagnosed, circuit is simulated by computer. Typical parameters of every state are used to build fault dictionary. Distance algorithm is used to calculate the similarity between current circuit and every state of fault dictionary. Analog circuit with tolerance can be diagnosed by the distance. Firstly, the method of simulation-before-test is introduced to build fault dictionary. Secondly, familiar distance algorithm is resumed, such as Euclidean distance. Finally, an example of fault diagnosis of analog circuit with tolerance is provided. In the example, simulation-before-test and distance algorithm are combined to diagnose analog circuit with tolerance. Two distance methods are compared to explain the advantages and disadvantages of the Euclidean distance algorithm.

Abstract: Coriolis flow meters are used in measuring flow amount of natural gas and oil due to the good performance and high precision. Orthogonal decomposition algorithm is the most efficient algorithm with the highest precision in processing the digital signals of Coriolis flow meters, and digital filter design is vital important in the algorithm. In this paper we introduce a digital filter system combining the self-adaptive lattice notch filter and low pass filter embedded with Hanning Window or Kaiser Window, we also discussed the parameters selection and adjusting method deeply and systematically. For self-adaptive lattice notch filter, we calculate the key feedback parameter ρ based on bandwidth BW, leading the relative error of frequency calculated within 0.01%. For low pass digital filter, we adjust the filter order through monitoring the sine feature of the orthogonal component that has passed the low pass filter, and the relative errors of phase difference are within 0.1%. We also demonstrate the feasibility of this system through simulation under MATALAB system and calculating experiments data of Coriolis flow meter.

Abstract: In order to solve the problem of poor performance of the traditional calibration algorithm , the paper proposed a mathematical model under the constraints of nonrotating and nonscale error ,which solved the defects of inconvenience and expensiveness. Moreover, the mathematical model was obtained through the correlation equation based on the least squares method. Meanwhile , the paper discussed the impact of random noise on the model ,and it was simulated by Matlab. The result of the simulation shows that the model can separate the system error of circular artifacts accurately whether the existence of random noise or not. The result of this paper on expanding the application areas of selfcalibration is of great significance.

Abstract: All optical cesium (Cs) atomic magnetometer with high sensitivity is an important technique to detect weak magnetic field. The Cs vapor cell is filled with He buffer gas to reduce spin relaxation rate. However the pressure of He also influences the Cs atomic polarizability due to pressure broadening effect. In this work, the principle of all optical Cs atomic magnetometer is analyzed. The rate equation is used to calculate Cs atomic polarizability as the pressure of He is about 100Torr and pure Cs vapor cell. The calculation shows that higher pressure of He buffer gas can decrease Cs atomic polarizability without considering spin-exchange collisions, as the pump beam frequency is locked to Cs D1 transition F=3F=4.

Abstract: To verify the hypothesis that the variations of bioimpedance can reflect the status of bladder volume during natural bladder filling. We chose 10 healthy, male volunteers by recording different bladder filling stages using bioimpedance and ECG measurement. The signal measurement acquisition device was design by Sun Yat-sen University. Bioimpedance measurement was employed four silver-silver chloride compound electrodes, two of which are stimulating electrodes, and the others are measuring electrodes. Each electrode is attached to the lower abdomen, the mapping position of urinary bladder. Using Fourier analysis, the bioimpedance signals in different stages were analyzed. During natural bladder filling, subjects were asked to report real sensations. Sensations intensity increased with urine volume increase. Bioimpence power spectrum density (PSD) was related with sensation intensity. During natural bladder filling, PSD revealed two parameters with 0.04-0.15 Hz (low frequency, LF), and 0.15-0.4 Hz (high frequency, HF), which were observed under different bladder sensations. In natural bladder filling, the HF spectrum power is increased, in parallel with an inconspicuous change in LF spectrum. With the ECG signal analysis, the reaults revealed spectrum powers were explained by the autonomic nervous regulation. The novel method can assess the states of bladder volume during natural bladder filling.

Abstract: We present a camera calibration method based on circle plane board. The centres of circles on plane are regarded as the characteristic points, which are used to implement camera calibration. The proposed calibration is more accurate than many previous calibration algorithm because of the merit of the coordinate of circle centre being obtained from thousand of of edge pionts of ellipse, which is very reliable to image noise caused by edge extraction algorithm. Experiments shows the proposed algorithm can obtain high precise inner parameters, and lens distortion parameters.

Abstract: Back Propagation network, Widely used in automatic control, image recognition, hydrological forecasting and water quality evaluation, etc., as one of the Artificial Neural Networks, has stronger property of mapping, classification, functional fitting. This article takes the water flow of Lanzhou section of Yellow river as example by use of BP model to predict the water flow. It is well proved that BP network model can reach the purposes of early warning and forecasting.

Abstract: Performance test-bed of heat pump unit in central air-conditioner needs the intelligent and multifunctional software. So the monitoring software is designed with a good human-machine interactive interface, based on Visual C# development platform. The software can dynamically configure channels and measurement points to improve the defects of fixed channels for all measuring points in the traditional monitoring systems, which enhanced the flexibility and reliability of system. In order to increase the data accuracy, the improved digital filter algorithm was adopted. In addition, multi-threading mechanism was used to achieve serial communication and data processing, which meets the requirements of monitoring program for multi-tasking and real-time. The results show that monitoring software is powerful, easy to operate, reliable, high fault-tolerant and good user-friendly. It is suitable for using in other monitoring systems.