Applied Mechanics and Materials Vols. 668-669

Abstract: The basic principle of neutron detection was proposed in the twentieth century, especially G.F.Knoll compiled Radiation Detection And Measurement in 1979, including detailed in principles and methods of radiation detection and measurement on a variety of hot and fast neutrons. In recent decades there is not have a big breakthrough on the principle of neutron detection development, but there is a great improvement in the performance and scope of neutron detectors. Depending on the working principle of neutron detector, it is roughly divided into the following three: Gas detectors, Semiconductor detectors and Scintillator detector.

Abstract: Mechanism and functions of S-4800 Scanning Electron Microscope are introduced in this paper. The image-forming mechanism and structure of SEM are studied, and the signal transformation of secondary electron and backscattered electron is presented. The main application fields of SEM are researched.

Abstract: For single channel sound velocity measurement system accuracy was generally not high,a high-precision dual-channel sound velocity of seawater measurement system was designed.Based on ultrasonic speed of sound measurement in seawater with time-of-flight method,the system used ARM microcontroller to combine with high-precision time interval measurement chip,and the sound velocity measurement was translated into distance and time measurement. Then the influence of the time delay of the system was eliminated by method of difference.The paper introduced the modules of the system,and the high-precision time interval measurement method as the key technology of time-of-flight method for the velocity measurement system was expounded.It wasproved by experiment that the measurement accuracy of the system on the velocity reached 0.019m/s.

Abstract: Application of the IOT (Internet of Things) technology has promoted the “digital campus” developing into “smart campus”. This paper applies the sensor monitoring technology based on the IOT to the existing GIS underground pipeline management system, to achieve across species and a full range of real-time monitoring of the pipeline. Use sensors for collecting data, and RS485 communication bus and GPRS network for data transmission, and batch estimation data fusion method to optimize the monitoring data. It has practical significance to realize intelligent management of campus underground pipelines.

Abstract: This paper studies the on-line monitoring system of transmission tower stress.Firstly, it introduces the necessary of this system, gives its system architecture. Then it presents an algorithm to determine the stress sensors' installation points on the tower, which based on finite element analysis. Through calculating the stress distribution condition of different components of the transmission tower under typical working condition, these points with relatively higher failure probability in the transmission tower can be monitored by installing stress sensors on them. Finally, it uses a 500kV oxytropis tower as an example to show the algorithm flow.

Abstract: In this paper, we did the analysis of the gyro random migration using Allan variance method, static output data using a three-axis gyroscope of the global first integrated six-axis motion processing components MPU6050. Experimental result shows that the fitting of bias instability and angle random walk smoother, it not only improves the estimation accuracy of random walk coefficient, but also the amount of data required is greatly reduced.

Abstract: Real-time accurate voltage phase angle measurement data has a very important significance to monitor and analyze the power system, and phase angle measurement principle of Fourier transform plays an important role in the theoretical calculations and engineering applications. The dynamic sinusoidal voltage signal contains two parts of the sinusoidal steady-state component and decaying DC component, and the decaying DC component having a continuous spectrum, at the frequency corresponding to the sinusoidal steady-state component must have a non-zero value, making dynamic signal phase than steady signal phase has one extra deviation angle. Considering Fourier transform method and theory of engineering application are different, this paper only considered the application conditions of time truncation, analyzes continuous Fourier transform under a real eigenvalue and a pair of conjugate complex roots condition, then compared with the theoretical calculation, for the two case of limited time integration and theoretical calculation condition, the phase angle difference and influencing factors are given.

Abstract: Transformer is the main equipment of power system, its operation reliability is directly related to power system security and reliability of power supply. In order to guarantee the safe operation of power system, must strengthen the monitoring of the main transformer.With the development and popularization of intelligent station, the detection of transformers insulation is faced with the new problem that PT signal is not convenient to get and even unable to get. This paper proposes the relative method which is used to calculate and monitor dielectric loss of transformer bushing and designs the on-line monitoring device, through the data acquiring form the on-line monitoring instrument which are installed in the transformer of substation shows that this method has high precision, strong anti-interference ability.

Abstract: Boron steel nondestructive testing is of vital importance for the industrial production of boron steel plate to guarantee the product quality and production standards. This paper proposes a new kind of boron steel nondestructive detection scheme based on neutron radiation detection. We take advantage of the interaction between neutrons and boron steel media, to check whether the content of ¹⁰B in the product is qualified, uniformity meets the requirements, and whether there is a big flaw. Nondestructive testing scheme designed in this paper, using the neutron and ¹⁰B in boron steel plate has a larger reaction cross section. By receiving and counting the mount of neutron when they go through the stainless steel plate via neutron detector, we can conclude the reduction of neutrons and then calculated the content of ¹⁰B in products. This scheme sets polyethylene reflection at the bottom of the boron steel plate, on the one hand to strengthen the neutron count that the neutron radiation detector received by the reflection effect, on the other hand, can avoid defects like the opposite side receiving brings larger device volume, maneuver and others. This design provides a feasible technology and route for boron steel plate nondestructive testing.

Abstract: A method is described to measure temperature on rake face and flank face during high speed milling through the combination of using a non-contact infrared pyrometer and drilling two holes in the workpiece. One of the holes was vertical to the direction of feed for measuring the temperature of rake face, and the other was parallel to the direction of feed for measuring the temperature of flank face. The holes enabled probe beam of the pyrometer to go through them to reach the tool surface directly. The method avoids drilling any hole in the tool and can be used to measure the interface temperature directly. This technique has potential application in monitoring tool temperature and analyzing tool wear during machining of difficult-to-cut materials.