Perfect layers 3 free download5/6/2023 ![]() ![]() A nondestructive exploration can be achieved in means of seismic imaging. The excavation process in mechanized tunneling can be improved by reconnaissance of the geology ahead. It is shown that the proposed method is efficient and cost-effective for the in-situ characterization of the ultrasonic vibration of various cutting tools in RUM, especially for complexly shaped tools working in a local resonant state. ![]() Finally, a series of experiments are conducted by using the measurement system, including determining the working frequency of cutting tools and quantitatively describing the vibration amplitude in RUM. Secondly, based on the relationship between the acoustic pressure and tool vibration, the measurement strategy and corresponding in-situ measurement system for acoustic pressure are developed to characterize the tool vibration in RUM. Firstly, characteristics of acoustic pressure distributions radiated from typical cutting tools in RUM are comprehensively studied based on analytical analysis, numerical simulation, and experimental measurement. In this context, an in-situ characterization method for the tool ultrasonic vibration based on radiated acoustic pressure is presented in the paper. Although the existing optical and electrical methods have been widely used for tool vibration characterization in some scenarios, they still have obvious limitations when applied to in-situ characterization in RUM systems. The key to determining working frequency is to characterize the tool vibration. ![]() Since the frequency at which the vibration of various cutting tools reaches the maximum is probably different, it is necessary and important to in-situ determine the working frequency of cutting tools in RUM. Corresponding ultrasonic vibration units are often designed to work in a local resonant state rather than a full resonant state due to the diversity and complexity of tool shapes. In order to be used in the CNC machining center, one rotary ultrasonic machining (RUM) system needs to adapt to various cutting tools. The designed optical fiber methane gas sensor possessed the merits of ultra-high sensitivity, providing helpful guidelines for the fabrication of high-performance methane gas sensors. To our best knowledge, we presented the methane gas sensor based on VE in two parallel optical fiber Sagnac loops for the first time. According to the numerical simulation, the average sensitivity based on two parallel Sagnac loops in the methane gas concentration of 0-3.5% was 197.775 nm/%, which was 5.5 times in contrast to a single Sagnac loop. The finite element method (FEM) was used to assess the methane gas sensor’s sensing capabilities. Vernier effect (VE) was generated and as a result the sensitivity was improved by multiple times. The reference arm contained a polarization maintaining photonic crystal fiber (PM-PCF), while sensing arm consists of a methane gas sensitive film coated PM-PCF. In this paper, we proposed an ultra-high sensitivity methane gas sensor based on Vernier effect in two parallel optical fiber Sagnac loops. Methane gas sensing has attracted great interest for its applications in agriculture production, industrial manufacturing, medical diagnosis, and environmental monitoring. ![]()
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