Advanced Materials Research Vols. 694-697

Abstract: Based on stress wave detection technique and wavelet analysis, oil pipeline leakage detection system is designed. Through vibration sensor put on the pipeline, vibration signal of pipeline is collected. The signal is used to preliminary assessment with DSP processing unit within the system, and then the feature of threat events is extracted. The information is uploaded to the centre of security central station of system by GPRS signal. At this, signal wavelet analysis is done for leakage detection. Based on LabVIEW platform, on oil pipeline leakage monitoring interface, threat events is alarmed and shown in electronic map and the system is convenient for staff to handle with. With the test, recognized police rate of system is superior to 85%, rate of false alarm is 15% below. All knocking signal of pipeline is given right alarm information. The noise by people walk, car, wind and rain is effectively filtered.

Abstract: An analytical method of time character of electron beam current density is required for transmission electron microscopy (TEM) imaging research. By studying the imaging principle of TEM, the relational expression between current density on fluorescent screen and exposure time is deduced. The actual data of numerical relation between current density and exposure time are gained by the exposure experimentation with the master sample on the TEM test equipment. Furthermore, the parameter value in expression is computed by linear fit using the least squares method, and then the concrete relational expression between current density and exposure time about the TEM test equipment is obtained. As a result, using the concrete relational expression on the TEM test equipment, the automatic exposure experimentation on some samples is completed on the different operating mode, and the relatively clear-cut TEM images are formed. The experimentation results indicate that the automatic exposure method is correct and parameter calibration is valid.

Abstract: Aiming at rolling bearing fault signal of the non stationary feature, Apply a new method to the rolling bearing vibration signal of feature extraction, which is combined the Empirical Mode Decomposition (EMD) and the Choi-Williams distribution. Firstly, original signals were decomposed into a series of intrinsic mode functions (IMF) of different scales. To the decomposed each IMF component for Choi-Williams time-frequency analysis, Then take the linear superposition, finally obtained the rolling bearing vibration signal of Choi-Williams distribution. After the analyses of the rolling bearing inner ring, outer ring and rolling element fault signal ,the results show that this method can effectively suppress the frequency aliasing and interference caused by cross terms. And be able to accurately extract the fault frequency of the bearing inner ring, outer ring and rolling element, lay the foundation for the subsequent rolling bearing state recognition.

Abstract: The measuring body of PRS-2 cigarette paper smoldering rate tester is industrial vision sensors P4E1.3, it could determine and identify the burning of the cigarette paper by using the advanced computer image processing techniques.The vision sensor can detection to 10,000 times per minute when the image resolution is 1.3 million pixels-accurate, it simultaneously monitors the 5 cigarette paper, and can ensure that the scanning frequency of each cigarette paper is not lower than 100 Hz. In the case of deducting the necessary analysis and calculation time, it can guarantee that the timing accuracy is no less than 0.1s. The instrument is able of detecting the serrated depth of the burned cigarette paper line and excludes the misjudgment which caused by human factors,so it could achieve control, data analysis, save and print independently.

Abstract: Knock is a major cause of pollution, parts damage and metallic noise in an engine. But slight knock can improve the power and economic performance of an engine. Therefore, existence and intensity of the knock are preconditions for the automatic knock control system to work. This paper describes an advanced approach solving the knock detection task. It is based on a time-frequency image generation solution followed by a support vector machine detection step trained in a constructive supervised way. The proposed method is applied to analyze the pressure signals measured from an engine cylinder to detect the knock based on the popular cycle-by-cycle classification. It is shown that this approach can qualify well for knock detection.

Abstract: Tower cranes are widely used in the course of construction machinery and equipment. In this system, tower cranes work more safely and stably, and the controlling system becomes more accurate, which is very vital to improve efficieney, aviod accidents and analyze fault.With the rapid growth and population of the wireless network technology, ZigBee wireless network technology by virtue of their low rate, low power consumption and low cost, has been widely applied in the fields of wireless sensor networks and automatic control. The real-time condition monitoring system of tower cranes based on wireless sensor network is studied in this paper.

Abstract: A 40-GHz optical pulse train is generated by using of one optical delay line and two cascaded electro-absorption modulators driven by 20GHz-sine-wave signal at very low bias voltage (-0.8V) in conjunction with a tunable distributed feedback (DFB) semiconductor laser. An approximate transform-limited optical pulse, with pulse duration of width less than 7ps, the spectral width of 0.3nm and the side-mode suppression ratio (SMSR) of about 17dB was obtained in experiment. Keywords: OTDM, EAMs, optical pulse, less cost.

Abstract: In this paper, a novel genetic-algorithm-based AMC structure, which is made up of high-impedance frequency selective surface, is introduced. The aperture-coupled microstrip antenna using this structure has 10dB less back radiation and 3~4dB more gains than a conventional one. This structure has important reference value to the manufacture of antenna. Practical antenna is fabricated, and the measured results basically agree with the simulated well.

Abstract: This paper presents an efficient detail-preserving random-valued impulse noise filter. The proposed method introduced an image statistic, the decision-based rank ordered absolute differences (DROAD for short), to distinguish image details from impulses. This reduces the probability of detecting image details as impulses. Besides, in order to search for suitable thresholds at noise detecting phase, we present the Q-estimate of variance in noisy image. According to image variance, we define a threshold for each pixel. This makes more impulses can be identified. Experiments results show that our filter provides a significant improvement over many other existing techniques.

Abstract: The converter topologically conjugates with its symbolic time series by mathematical demonstration, the time series of converter are translated into symbolic series based on return map. This study takes one-order DCM Boost as examples, time irreversibility and block entropy of different word lengths in DC-DC converters are analyzed by using coarse-grained discretization. Reasonable coding method of symbolic series is determined from statistics perspective, which can provide theory basis for digging into nonlinear characteristic and chaos in DC-DC converter.