Applied Mechanics and Materials Vols. 427-429

Abstract: Real-time magnetic resonance imaging (MRI) has many advantages as compared to traditional MRI and can be used for the visualization of dynamic moving cardiac structures and functions without cardiac gating, as the fast data acquisition apparently freezes the motion resulting from heart beating and lung breathing. During the past decades, fast pulse sequences and image reconstruction algorithms had been developed to improve the temporal resolution with acceptable spatial resolution. However, the bottle neck of current real-time MRI systems is the availability of a user-friendly prescription tool to allow a MRI technician to prescribe the 6-Degree-of-freedom imaging plane of the MRI system. To meet the needs of real-time MRI, a 3D input tool is developed which facilitates user interactive specification of the center position and plane orientation of the MRI imaging plane. This paper reports such a custom designed 6 degree-of-freedom 3D input device, which allows the user to interactively and intuitively manipulate the scan plane to direct the real-time imaging capability to a target position based on the visual feedback provided on the MRI console in the form of real-time MRI images

Abstract: Road quality information detect system is an important component in architecture quality detect system, also is the basement of successfully working of other related project for the whole country. The study of detecting the road crack is the key to insure the security of accurately detect the road quality in transportation system. In this paper, we come up with a fixed way of road undersized rift image detection by using cellular neural networks. By image processing, building rift networks and details networks and adding the model of similarity undersized rift networks. It can avoid the problem that can not accurately detect undersized crack by only taking the crack feature value. The experiment proved that fixed crack detect computing is easy to do, more accurate to detect the undersized cracks on the road and can reach the standard level of current detect technique.

Abstract: This paper deals with the development of an alternative approach for sonic distance measurement. A linear frequency modulated signal (chirp signal) is regarded as a template signal. The sonic distance measurement system transmits the template signal and receives the echo signal, then calculate the correlation between template and echo signal. The time of flight is determined according to the position of the peak in the correlation result, then the distance is calculated. The major advantage of this approach is that it can detect weak echo signals among noises and increase measurement range significantly.

Abstract: A scheme producing non-linearity frequency-modulated signal which can be updated on-line based on AD9858 is mentioned. A method to design NLFM signal using immediate data update is introduced. Circuit structure is designed. Major factor that impacting data is analyzed and its solution is presented. Experiments certify that this method can generate broadband and narrow pulse width non-linearity frequency-modulated signal, whose frequency spectrum can be updated on-line in real time.

Abstract: Global Navigation Satellite System (GNSS) signal simulator is one of the most important instruments for testing the function and performance of GNSS terminal products. It consists of a Mathematical Simulation System (MSS) and a Radio Frequency Signal Generator (RFSG). The MSS is responsible for generating the navigation message and observation data and then sending them to the RFSG in real time. The simulation accuracy of each part in the MSS determines that of the signal generated by the RFSG. In this paper, the function requirements of each module in MSS are analyzed firstly. Then the general framework of MSS is presented. At last, MSS developed in this paper is demonstrated and tested partly, the test results are compared with that of SimGEN software and STK. Taken as a whole, the MSS has complete functions and good performance. The MSS will hopefully apply to GNSS signal simulator.

Abstract: In the galvanic coupling intra-body communication, transmitting and receiving of signals require coupling between electrodes and human tissue. Electrode size has a direct effect upon signal attenuation so as to influence signal transmission. To analyze the exact effect of electrode size on signal attenuation, the volume conductor model of human forearm is built with COMSOL Multiphysics 4.2a.It can be found from the simulation experiment that, signal attenuation declines with the increase of electrode size, which lays the foundation for subsequent experiments.

Abstract: As the key junction between the ground and underground, hoisting systems as well as mines themselves are of vital importance to coalmine production. Laser ranging method is studied as a new solution of getting the real-time position directly. Furthermore, multi-scale phase based laser ranging principles are utilized in the system. The paper is aimed to conduct research into the problems existing in standard signal generating while using laser to locating the hoisting container, and to design standard sine generator circuits with DDS technology and DDS devices AD9850 to generate multiple frequency standard signals. In view of the serious noise disturbance in high frequency output, 4-order Chebyshev low-pass filter is designed, by using the integrated analog filters LT 6600-15, to filter the sine signals from AD9850 and to effectively weaken the noise disturbance. The established practical circuits are tested, obtaining trillion level high frequency and low frequency sine signals and fulfilling the requirements for the location system of hoisting containers.

Abstract: To achieve the accurate extraction and characteristics analysis of electrical signal in plants, the system was developed for detecting and extracting weak electrical signal in plants. As experimental platform for the extraction and detection of plants electric signal, training experiment system on the growth of plants, had done the experiments of extraction and feature analysis on plants electric signal by it, described in detail the extraction and analysis process of plants electrical signal, and also discussed the methods of anti-interference process for the system. The system construction is feasible, it has positive significance for real-time monitoring the environment factors changes and the plants growth status.

Abstract: According to general piezoelectric acceleration sensor measurement circuit existing problems in the dynamic testing field, the paper proposes the modular, integration design method, using the integrated chips CA3140 to design the signal disposal circuit, in order to reduce the cost and improve the circuit SNR, enhance the stability and reliability of the circuit. This circuit includes a charge amplifier, conditional amplifier, low-pass filter, high-pass filter and output amplifier. The test shows that the circuit functions are complete, it is practical and reliable. It has a higher performance price ratio, and can be widely used in the dynamic monitoring and the diagnosis of fault or defect about the equipment and structure.

Abstract: To increase fault classification performance and reduce computational complexity,the feature selection process has been used for fault diagnosis.In this paper, we proposed a sparse representation based feature selection method and gave detailed procedure of the algorithm. Traditional selecting methods based on wavelet package decomposition and Bhattacharyya distance methods,and sparse methods, including sparse representation classifier, sparsity preserving projection and sparse principal component analysis,were compared to the proposed method.Simulations showed the proposed selecting method gave better performance on fault diagnosis with Tennessee Eastman Process data.