This article provides a dynamic model of a cylindrical roller bearing–rotor system by combining the finite element method of the rotor and the interaction between the components of the bearing to study the dynamic response of the rotor with asymmetric support mode. The shaft is discretized by beam elements with five degrees of freedom. The bearing inner ring is consolidated with the journal of the shaft. The simulation results show that variable compliance vibration can stimulate resonance of the rotor in the sub-critical speed region. The variable compliance vibration of the rolling bearings does not occur synchronously on both sides of the asymmetric supported rotor. The increase in radial load and clearance exacerbates variable compliance vibration, while rotor imbalance has a smaller impact on variable compliance vibration. Usually, the presented coupled model can be applied to the comprehensive analysis of the vibration characteristics of all components in any cylindrical roller bearing–rotor system.

The paper presents a design method of temperature control system of medical instrument based on dual threshold hysteresis comparison circuit. The system adopts a negative temperature coefficient thermistor as the temperature sensor and a thermoelectric cooler as the control object. By means of this method, the working temperature in the medical instrument ranges from two degrees centigrade to four degrees centigrade accurately. According to the test results the design scheme is optimized and improved. The design method is scientific, effective and economic by experiments.

More than 90% of a person’s lifetime is spent indoors in a variety of activities, thus the parameters of the home environment affect human physical and mental health. With the development of Internet of things technology, people put forward new and higher requirements for the smart home. Based on the microcontroller, in this paper, we use multiple sensor systems to monitor various indoor environmental parameters, that is, to collect and display the environmental temperature, humidity, light intensity, CO concentration, and smoke concentration accurately and in real time. In the process of monitoring, the limits of various environmental parameters can be set artificially. Different types of alarms will be activated when one or several parameters are detected to exceed the limits. The microcontroller transmits the monitoring data to mobile terminals such as smartphones and others through Bluetooth modules, and the display interface is clear and intuitive. After testing, the system has the advantages of accurate measurement results, stable performance, and simple operation, which has a certain promotion and use value in smart home environment monitoring.