Advanced Materials Research Vols. 655-657

Abstract: The wireless sensor network (WSN) is the development trend of the technology of sensor. This paper, based on the nRF905 wireless module, introduces a wireless temperature gathering and transmitting system. From RF modules and master control module, the hardware platform has been designed, beyond that, the paper introduces the temperature sensor network software design. The test show that the system is stable, and data are reliable.

Abstract: Chemical sensors is gaining long-standing interests due to their applications in many areas such as bacterial and virus detection, medical diagnostics, drug development, food safety and environmental control. Among the existing chemical sensors, optical planar sensors show promising and attempt to beat their commercialized competitors because of their robustness, lable-free detection mechanism, mature complementary metal oxide semiconductor (coms) fabrication technology and naturally low cost. Silicon nitride microring resonators were demonstrated as chemical sensors. Using the technique of coms technology, the microring devices were fabricated with 200 µm in radius. Performance of the devices was measured, which showed the quality factor (q) was up to 25,000. Sensitivity of 108.9336 nm per reflective index unit (nm/riu) and detection limit of 1.836×10-4 riu were demonstrated by using various concentrations of ethanol solution as analytes.

Abstract: Along with the computer hardware and software to continuously improve and the performance of the price going down, machine vision technology more and more application in agricultural product quality inspection and grading field. The characteristics of the machine vision technology is speed, information and multi-function, can complete the grading of the size, shape, color, defects, and many other. Apples and other fruits at home and abroad are relatively mature, however, due to growing location, dried jujubes machine vision grading is few studied. This article mainly discusses the choice of dried jujubes background and size detection. The results show that at the same time ensure enough in production, sorting accuracy can reach 80%-85% or so. Machine vision also apply to dried jujubes real-time classification.

Abstract: The fiber Bragg grating (FBG) sensor is the most appropriate to measure strain of concrete. Employing a specifically designed FRP package, a FBG sensor for concrete dynamic strain measurement was designed. To interrogate the dynamic response of the FBG sensor, the corresponding interrogator was developed by using a novel reflect wavelength measurement method. A series of tests such as measuring dynamic strain of concrete specimens impacted with drop hammer and split Hopkinson pressure bar (SHPB) were conducted. The results show that the sensor and its interrogator respond rapidly to impact and have a stable performance. The system can be used for a real-time and rapid dynamic strain measurement in concrete dynamic performance tests or weapons effects tests.

Abstract: Fiber Bragg Grating sensor network plays an important role in the field of large-scale engineering and major equipment condition monitoring and diagnosis. The heterogeneous convergence between FBG sensor network and the Internet constitutes the FBG sensor network of Things which can future expand the network applications range and enhance the condition perception and monitoring capabilities. In this paper, the heterogeneous convergence model between FBG sensor network and the Internet is built. Based on the model, heterogeneous convergence principle and method between FBG sensor network and the Internet is introduced from three layers: perception layer, convergence processing layer and application layer. According to the theory and method, a condition monitoring and fault diagnosis system for the harbor machinery in the WAN environment is presented. The system physical running effect in the working field demonstrates the effectiveness and the rationality of the convergence method.

Abstract: A new elastic element of fiber Bragg grating(FBG) accelerometer which is four peripheral clamped trapezoidal beams is developed. The simulation of this elastic element with ANSYS is carried out. From the results, it shows that as an elastic element, four beams have the advantages of lower cross-axis sensitivity which is smaller than 52 dB and nearly uniform strain along the grating area. In addition, its work frequency is higher than the single beam constituting four beams. This kind of elastic element not only can be used with fiber Bragg grating accelerometer, but also other types of sensors.

Abstract: The advantage of the electromagnetic tomography is introduced briefly. Based on conjugate gradient algorithm, modified conjugate gradient algorithm for electromagnetic tomography (EMT) is proposed, which improves quality of reconstructed image and convergence speed efficiently. In the light of the lab electromagnetic tomography system, modified conjugate gradient for reconstructing images is verified. By evaluation of image error and the relevance, regularization, Landweber, conjugate gradient and modified conjugate gradient algorithms are compared. It can draw the conclusion that for different flow models, image error and the correlation using modified conjugate gradient algorithm is superior to the others in lab EMT system.

Abstract: Generally ,it was precession of flexible gyroscopic not gyroscopic nutation which was just considered in engineering design. However, in photoelectric stabilized platform, this nutation characteristics of angular position flexible gyro has been restricting the stabilized accuracy of platform seriously. In this paper, firstly the output characteristics of a miniature flexible gyro was measured by characteristic of gyroscopic motion, four main kinds of frequency components in output characteristics was analysed. The methods were realized in the miniature flexible gyroscope in the laboratory by adopting the two measures of the secondary trap circuit and improvement of torque component.Test results showed that, the improvements made nutation frequency of gyro and envelope at 40Hz converged fastly , and the output noise of gyro angular position was decayed to more than15dB. In the end, the gyro was applied to chariot photoelectric stabilized platform ,the isolation of platform and carrier got improved from 1~2mil to 0.3mil.

Abstract: For the multi-channel ARMA signal with two sensors, by the classical Kalman filtering method and the covariance intersection (CI) fusion method, a covariance intersection fusion steady-state Kalman signal smoother is presented, which is independent of the unknown cross-covariance. It is proved that its accuracy is higher than that of each local Kalman signal smoother, and is lower than that of the optimal signal fuser weighted by matrices. The geometric interpretation of the above accuracy relations are presented based on the covariance ellipses. A simulation example result shows its effectiveness and correctness.

Abstract: The SAW delay-line sensor can obtain the energy of the RF pulse query signal through the wireless method. The RF pulse echo signal of the SAW delay-line sensor is significant effected by the different query pulse width of the RF pulse query signal, which is directly related to the sensor precision. The size of the IDT and reflectors, the distance between the IDT and reflector, and the distance among the different reflectors can affect the selection of the RF pulse query signal. The selection method of the query pulse width is discussed through the theoretical analysis and experimental analysis according to the SAW delay-line transmission characteristics. The query pulse width can be calculated directly through the design parameters of the SAW sensor.