Applied Mechanics and Materials Vols. 313-314

Abstract: Capturing an iris image rapidly is required for iris image acquisition embedded system. For the traditional method, an iris image must firstly pass through the quality evaluation, which is complex, so the acquisition speed is very slow. This paper described an iris acquisition embedded system, and a new capturing method. The system includes an DSP DM642, and some relevant peripherals. When an image is acquired, it is filtered by the capture-control function, if passed then be stored the image, until capturing the assigned amount. Using this method, we can rapidly capture the high quality iris images at about 0.8s, and 83% of the stored images can be used for the next procedure. At the same time, it is convenient for the user to capture.

Abstract: In this paper, we consider the existence of positive solutions for nonlinear Lidstone boundary value problems. An new existence result is obtained by applying the fixed point index theorem.

Abstract: Because of wind speed with the randomness and non-stationary properties, wind power has a great effect when it integrates to power grid. We can only prediction a more accurate wind speed to reduce its harmful of the power grid. However, it is difficult to make more accurately forecast because of its characteristics. This article we discuss a method that wind speed processed by wavelet at first, then giving a different quantile points forecast of each layer of wind speed decomposition using the quantile regression, finally we gain the differential forecast by reconstruction every layers predict. The result shows this method prediction effect is better than quantile regression forecast and ARMA model prediction, especially in the extreme points.

Abstract: The finite element model of electric stop valve with flange bolts preload and valve stem force was established to improve the valve stress calculation method which was based only on action of fluid pressure, thermal stresses and pipe reaction forces. The principle and application of pretension load elements were expounded. By ANSYS, the stresses of this valve with preload and valve stem force were calculated, and the Mises equivalent stresses contour and some values of key position of whole valve were obtained. The results indicate the influence of the stresses on the valve caused by preload of bolt mounted on the flange and valve stem force can not be ignored.

Abstract: The problem of schedulability test of real-time task in scheduling system has been addressed. In such as real-time scheduling problems with uncertain interrupt operation, Quantified Constraint Satisfaction Problems (QCSP) were introduced to model and solve CSP involving uncertainty or uncontrollability on the value taken by some variables. In this paper, we propose to a novel approach to schedulability test based on the QCSP model. Based on the QCSP model of scheduler and interrupter in the real-time scheduling system, we transform the schedulability test into the satisfability problem. Finally, we design the algorithm QCSP-SchTest for judging the satisfability of a schedule S(α). This leads to a new schedulability test method without considering the specific scheduling algorithm or strategy.

Abstract: The objective of this paper is to propose a method for exacting the characteristic frequency components of blood flow signals based on wavelet transform. The wavelet transform technique, a time-frequency method with logarithmic frequency resolution, was used to analyze oscillations in human peripheral blood flow measured by laser Doppler flowmetry (LDF). In the frequency interval from 0.008 to 2.0 Hz, the LDF signal consists of components with five different characteristic frequenciesmetabolic (0.008-0.02Hz), neurogenic (0.02-0.06Hz), myogenic (0.06-0.15Hz), respiratory (0.15-0.4Hz) and cardiac (0.4-2.0Hz). The five frequency components were extracted in time domain and reconstructed using cubic spline interpolation in this study. The results showed that it was an effective way to extract each component of blood flow signals.

Abstract: Pipeline leak lead to huge economic losses and environmental pollution. Leak detection system based on single sensor negative pressure wave often causes false alarm. In this paper the double sensor method is adopted to exclude false alarm by determining the propagation direction of the pressure wave. In order to remove the inverse coherent interference caused by pump running, the phase difference of primary low frequency component is used to identify the sign of the time delay between the double sensors. The experiment shows the mothod is effective.

Abstract: In order to use the STAP in reverberation suppression, and compare the performances of STAP for underwater LFM with CW, the method of STAP used for LFM was proposed. Firstly, the principle of STAP for CW was analyzed, according to the underwater echo of CW. Then, the space-time steering vector of LFM is deduced by analysing the underwater echo of LFM. Fianlly, the performances of STAP for LFM and CW were compared by simulations. The results show that the proposed method of STAP for underwater LFM with narrower modulation bandwidth can achieve a better performance in target detection and estimate, and the processing gain of STAP for CW is higher than that of LFM form 1.6dB to 5.5dB with the modulation bandwidth from 100Hz to 600Hz.

Abstract: This paper focuses on the robustness of estimates and its mechanism with presence of short-term noise. Simulation results show that although AG estimator derives lower bias and better robustness than the GPH in most situations, the modification effects are evident only when the short noise has small negative roots. The problem of over-modification on larger negative roots and the under-modification on the positive roots are still lack of advanced study. The standard deviation it is not sensitive to short-term noise but the mean square errors increase sharply with short-term noise. Besides, the power and practical size of the test was affected too. Larger sample size is suggested to gain more robust finite sample properties.

Abstract: In terms of the developing actuality of mixed-signal circuits, several familiar diagnosis methods are introduced in the paper including the basis principle, the merits and demerits for each method. At the same time, the design for testability based on Boundary scan is discussed. At last, the developing trends of this field is predicted.