In recent years, the application of gas sensors is becoming more and more extensive. Driven by potential applications such as the Internet of Things, its technology development direction begins with miniaturization, integration, modularization, and intelligence. However, there is a bottleneck in the research of interface circuits, which restricts the development of gas sensors in volume, power consumption, and intelligence. To solve this problem, a MEMS gas sensor interface circuit based on ADC technology is proposed in this paper. Under the condition of the Huahong 110 nm process, the working voltage is 3.3 V, the resistance change of 100 Ω~1 MΩ can be detected, the conversion error is in the range of 0.5~1%, and the maximum power consumption is 986 μW. The overall layout area is 0.49 × 0.77 mm2. Finally, the correctness of the circuit function is verified by post-layout simulation.
For a straddle-type monorail train gearbox, analyze the heating mechanism and heat transfer mode of each element in the gearbox, establish a heat transfer model of the gearbox, use empirical formula to calculate the heating power of each heating element, and use the flow field analysis to monitor it. Accurately calculate the convective heat transfer coefficient for the volume fraction of oil and gas in each cavity. Using the method of finite element simulation, the influence of different oil injection and large spiral bevel gear steering on the temperature field distribution of the gearbox is calculated and analyzed. The results show that when the large spiral bevel gear turns for a certain amount of time, the maximum temperature of each part of the gearbox at high oil level is higher than that at low oil level; When the amount of oil injection is constant, the temperature of each part in the reverse rotation of the large spiral bevel gear is higher than that in the forward rotation. This article provides the main reference for the prediction of the temperature field of the gearbox of the straddle monorail train and the improved design of the lubricating oil passage in the gearbox.
Deep cryogenic treatment (DCT) is a one time permanent process. In DCT, the material is slowly cooled down to the soaking temperature, is held at soaking temperature for a period time, and is heated back to room temperature. DCT process factors have their own effect on the mechanical properties of material. The paper studies the deep cryogenic treatment process of YT15 carbide inserts by orthogonal experiment method, and analyses the effects of various cryogenic treatment process parameters on mechanical properties, and observes microstructure before and after DCT by the scanning electronic microscope (SEM). The results show that the effect of soaking temperature on the properties of inserts is the first factor, the cooling rate and the tempering temperature is secondary and tertiary. Deep cryogenic treatment improves the multi-type martensite transformation of Co. Therefore deep cryogenic treatment increase hardness and enhance wear resistance of the carbide insert. Keywords-deep cryogenic treatment carbide insert orthogonal optimization martensite wear resistance
In order to improve NC machining precision this article analyzes the effects of cutting force on NC machining precision by means of simulation, and builds up the mathematical models of CK7815 feed drive system and radial action force of cutting feed, in order to study the effects of cutting load torque and radial cutting force on work pieces processing precision. The simulation results illustrate that cutting load torque and radial cutting force have respectively effects on axial precision and radial precision of work piece. The bigger is cutting load torque, the bigger is axial error. The smaller is cutting process coefficient and the higher is converting spring stiffness of lathe and tool, the smaller is radial error. In practice NC machining precision is improved by trying to decrease the cutting load torque and cutting process coefficient and increase converting spring stiffness.
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