Printed circuit boards (PCBs) are an essential component of electronic products, and detecting solder joint defects is critical in the PCB production process. Machine vision technology allows detection with high efficiency and cost-effectiveness. Therefore, this paper summarizes the basic principles of image processing-based and machine learning-based methods for defect detection and compares the advantages and disadvantages of both methods with relevant performance evaluation indicators. Finally, this paper contains a summary and an outlook.
With the development of the Internet of Things technology and the continuous improvement of people’s living standards, smart devices based on the Internet of Things are emerging one after another and intelligent mattresses are one of the important research directions. Many scholars at home and abroad have conducted a lot of researches on the vital signs monitoring of intelligent mattresses to improve the efficiency of elderly care. This article introduces the monitoring technology of intelligent mattresses, expounds the mainstream data collection methods and data analysis methods, comparative analyzes the advantages and disadvantages of different monitoring technologies and discusses the application of intelligent mattresses in vital sign monitoring, sleep monitoring and elderly care, finally summarizes and prospects the development of intelligent mattresses.
The fault tree(FT) analysis method plays an important role in system safety analysis and has been widely used in large and complex engineering systems. Therefore, this paper expounded the basic principles of FT analysis, using object-oriented programming technology, developed FT analysis and calculation software in the VC environment, and realized the drawing, qualitative and quantitative analysis of the FT. Finally, the effectiveness and usability of the software were verified according to the application analysis of an engineering example, and it has a certain engineering application value.
In recent years, the research and development of environmental action monitoring at home and abroad are in full swing. RF sensing has achieved a series of breakthrough research results based on its advantages in the application of behavioral identification, positioning and target monitoring. This paper first introduces the application scenarios of RF-awared environment monitoring and compares them with traditional environmental monitoring technologies. Then it analyzes the basic principles of RF sensing technology and the applications of signal acquisition method, feature extraction method, fingerprint database establishment method and machine recognition method in behavior recognition, positioning and target monitoring. Finally, the limitations of the current research and the future development directions are pointed out.
A structure in photonic integrated circuit with a microring serially connected by an optical attenuator is proposed to generate the non-reciprocity by the nonlinear optical effect in microring. We find that when the information of the transmission spectra of both forward and backward directions is utilized for sensing, the precision of sensing can be enhanced. We calculate the non-reciprocity ratio of our proposed structure, and utilize this spectrum for sensing. Simulation shows the non-reciprocal spectrum varies with the attenuation value of the attenuator. The slope of 4.34dB/GHz can be achieved by utilizing 10dB attenuator, and the sensing frequency range is 7.35GHz. These results benefit its application in sensing.