Search

This paper mainly introduces the sintering process of the monolithic capillary wick and analyzes the influence of different copper powder particle size, filling rate, copper powder shape and heat source size on the heat transfer performance of the isothermal plate. The experimental results show that: (1) For the isothermal plate sintered with spherical copper powder, the capillary force of large particle size copper powder is small, but the flow resistance is also small, and the performance of the isothermal plate sintered with large particle size copper powder is better. (2) In the case of low filling rate, the isothermal plate is dried due to insufficient return fluid. In the case of high filling rate, on the one hand, the thickness of the liquid film at the evaporation end of the isothermal plate is large, resulting in additional thermal resistance. On the other hand, the thin film evaporation mode will be transformed into pool boiling mode, which will reduce the heat transfer performance. (3) Spherical copper powder sintered plate with regular shape has the best performance, while dendritic copper powder sintered plate has relatively high thermal resistance. (4) The heat source area has a great influence on the thermal resistance of the plate. Under the same heating power, the thermal resistance of the small area heat source is much higher than that of the large area heat source; The thermal resistance of sintered copper plate is lower than that of pure copper plate under two heat source areas.

Aluminum and alloy tubes are widely used in industrial fields because of the advantages of good corrosion resistance, high thermal conductivity and light weight. Due to the stress corrosion cracking (SCC) and fatigue corrosion cracking (FCC), both inner and outer cracks generate in the aluminum tube. It is still a challenge to inspect all inner and outer surface cracks in the thick-wall aluminum tube in real time by one pass scan using the nondestructive testing (NDT) method. A double frequency circumferential current field testing (CCFT) method is presented for the inspection of both inner and outer cracks in the aluminum tube by one pass scan. A simulation model is proposed to extract characteristic signals of inner and outer cracks at two excitation frequencies. The bobbin-type probe with sensor array is developed and excited by the synthetic double frequency excitation signal. Both inner and outer cracks are tested by the double frequency CCFT system. Results show that both inner and outer cracks can be identified, distinguished and evaluated by the double frequency CCFT method by one pass scan.

Background: The progress of modern society and changes in lifestyle have not only increased the proportion of sub-healthy people, but also caused many people to suffer from sleep disorders and mental anxiety. Long-term lack of high-quality sleep will not only cause psychological problems such as anxiety and fatigue, but also cause physical abnormalities, such as abnormal hormone secretion, weakened immunity, neuroendocrine disorders, and high blood pressure. Therefore, the purpose of this study is to systematically evaluate the effectiveness of aromatherapy in improving sleep quality in people with sleep disorders. Methods: Computer search CNKI, SinoMed, Wanfang, PubMed, Web of science, and EMbase collect randomized controlled trials on aromatherapy to improve sleep quality of people with sleep disorders. The search time limit is to build the database until April 5, 2021. RevMan5.3 software is used for meta-analysis. Results: This systematic review will provide an assessment of the current state of sleep disorders, aiming to assess the efficacy of aromatherapy for patients with sleep disorders. Conclusion: This systematic review will provide a credible evidence-based for the clinical treatment of sleep disorders with aromatherapy.

In order to fuse information and analyze correlation more efficiently and flexibly, an air traffic management (ATM) knowledge graph-based method is proposed to reorganize the information flexibly and manage the fusion process dynamically. After that, a breadth-first and depth-first search-based correlation analysis method is designed to find deeper correlations and improve the searching efficiency.

Imaging and evaluation of inner-wall cracks are significant for the integrity management of aluminum tubes. In this paper, a novel bobbin coil probe with sensor arrays is presented for the imaging and evaluation of longitudinal cracks inside aluminum tubes. The finite element method model is developed to analyze the characteristic signals of the crack. The bobbin coil probe with inside tunnel magneto resistance (TMR) sensor arrays is developed for imaging of inner-wall longitudinal cracks. The depth and length of longitudinal cracks are evaluated by the characteristic signals. The results show that the detection sensitivity of the longitudinal crack can be improved greatly when the lift-off of the bobbin coil decreases with inside TMR sensors. The inner-wall cracks inside the aluminum tube can be imaged visually using the bobbin coil with inside TMR sensor arrays. The crack depth and length can be evaluated accurately by the detection sensitivity of the Bx in and the distance between the peaks of the Bz in respectively.

In this paper, we will build a question answering system for the field of air traffic control, which can assist controllers in monthly training better. The air traffic control question and answer system consists of a search based question answering system and a generation based question and answering system. The search based question answering system maintains an air traffic control problem set, uses word2vec to segment the questions and cosine theorem to calculate the similarity of the questions in order to match the best answer. To questions that can not be matched, we propose Attention-Based Bidirectional Long Short-Term Memory Networks to generate an answer.

It is still a big challenge to identify tiny surface cracks in a rugged weld due to the lift-off variations using the nondestructive testing (NDT) method. In this paper, the signal gradient algorithm is presented to identify the tiny surface crack in the rugged weld using the alternating current field measurement (ACFM) technique. The ACFM simulation model and testing system was set up to obtain the insensitive signal to the lift-off variations. The signal gradient algorithm was presented to process the insensitive signal for the identification of the tiny surface crack in the rugged weld. The results show that the Bz signal is the insensitive signal to lift-off variations caused by the rugged weld. The signal to noise ratio (SNR) of the crack identification signal was greatly improved by the signal gradient algorithm, and a tiny surface crack can be identified effectively in the weld and the heat affected zone (HAZ).