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Objective With the development of drilling technology for deep strata, the study of the dynamic characteristics and parametric response law of drill bits and deep complex strata during drilling has become a key and difficult point in research. Methods In this paper, a combination of numerical simulation and response surface analysis was used to study the dynamic characteristics of PDC bits and typical complex strata in the drilling process, and parametric analysis was carried out. In this paper, soft-hard-staggered strata with dip angles as a typical complex formation were studied, the dynamic damage finite element simulation model between the PDC drill bit and the soft-hard-staggered strata with the full real size was established based on Abaqus, and the dynamic characteristics of the drill bit subjected to the reaction force of the strata during drilling were derived. Numerical simulation experiments were also conducted by orthogonal tests to investigate the dynamic characteristics of the PDC bit under different formation parameters and drilling parameters. Results The single factor analysis and response surface analysis were used to model and identify the relationship between drilling parameters and stratigraphic parameters and the reaction force on the drill bit by the stratum and to obtain the changing trend and regression model of the reaction force on the drill bit by the stratum under multiple parameters. The results showed that the higher the inclination angle of soft-hard-staggered strata, the higher the average value and peak impact value of the bit subjected to the stratigraphic reaction force. The larger the ratio of softness to the hardness of the strata is, the larger the average and peak reaction forces on the drill bit. Within a certain range, increasing the rotational speed will reduce the impact of the reaction force on the drill bit. Conclusion The research results provide a basis for predicting the bit reaction force during drilling in deep and complex formations and guide the control of the drilling trajectory in deep and complex formations, which is of great significance for deep geological drilling.

Based on the analysis of earthquakes with M≥5 in Huayingshan fault zone and the present moderate and small seismicity, the background and regional seismicity characteristics in this area are discussed. It is considered that the southern section of the fault zone is the main seismicity area, especially in Yibin, followed by the middle and northern sections. The distribution characteristics of “quiet-active” period of earthquakes with M≥5, the law of “weak activity-enhancement” of earthquakes with M≥3, and the acceleration of strain energy release rate after Changning MS6.0 earthquake in 2019 provide references for the prediction of earthquakes with M≥5 in this area.

Convergence of ICDT is one of the important technical trends in the evolution of wireless mobile communication.How to realize the convergence of wireless network and AI technology is an important topic in the evolution of wireless network.Based on the concept of native AI, AI was applied for wireless resources optimization.6G context-aware wireless network architecture was proposed and AI was introduced into RRM to form an intelligent controller (AI-driven RRM), which completed the intelligent wireless resource management.Driven by big data and artificial intelligence, intelligent management of wireless resources was realized.In the deployment, the intelligent controller is deployed according to its functions and supports dynamic function scaling, so that it can be deployed independently of base station to minimize the cost of hardware.

A finite element model of the rotating band engraving into the forcing cone section of gun tube is established to explore the mechanism of engraving process of rotating band of a large-caliber howitzer under launch conditions. The dynamic engraving process of the rotating band is studied through numerical simulation, and the maximum resistance, engraving pressure and projectile velocity at the corresponding time are obtained. The deformation and groove formation processes of the rotating band are analyzed. The dynamic engraving resistance of the rotating band, the engraving pressure and movement of projectile are also calculated. The calculated results show that the rotating band undergoes plastic deformation and material flow, and forms the grooves on it due to ductile fracture, where shear failure is dominant. The rotating band has a layered feature after engraving, and the plastic strain in the band is small. The heat generated by adiabatic deformation of the rotating band is not enough to melt it. The simulation results of the deformation of the rotating band show good agreement with the test data from the recovered projectile. [ABSTRACT FROM AUTHOR]

Pot experiments were carried out to study the effects of NaCl stress on growth, ion distribution and chlorophyll fluorescence characteristics of Euphorbia lathyris L. The concentration gradient of NaCl was 0, 25, 50, 75, 100, 150, 200 and 250mmol • L-1. Results showed that plant fresh weights, dry weights and heights of seedlings decreased slightly at 25mmol • L-1 NaCl, but decreased significantly when NaCl concentration > 50mmol • L-1 High concentration of NaCl led to decrease of plant ions of K+, Mg2+ and Ca2+, and especially sharp decrease of the ratios of K+/ Na+, Ca / Na+, and Mg2+ / Na+. High concentration of NaCl also led to decrease of minimal fluorescence (Fo), maximum fluorescence (Fm), and PS II actual fluorescence efficiency. Significant Fo and Fm changes happened at higher salt stress (e. g. >25mmol • L-1 NaCl). It could be concluded that E. lathyris damaged photo - inhibition by NaCl stress. [ABSTRACT FROM AUTHOR]

With the gradual depletion of high-grade iron ore resources, the usage amount of low-grade iron ore is increasing year by year. Moreover, given the environmental protection requirements and the objective to reduce industrial cost, the usage of scrap is significantly increasing. The above occurrences have led to a large increase in the percentage of residual elemental arsenic in steel. Also, the requirement for lower arsenic content in finished steel is increasingly stricter. Presently, the iron and steel enterprises have not yet developed a mature technology for dearsenication in molten steel; moreover, the theoretical studies on the dearsenication in molten steel are relatively few, which lead to a lack of relevant theoretical data. Therefore, how to realize an effective method for dearsenication in molten steel is a technical problem in the iron and steel industry. Considering the problems of poor dearsenication in the steelmaking process and the previous experimental results of dearsenication in laboratory. The dearsenication in the process of steelmaking was investigated through an industrial trial of dearsenication in the molten steel in the ladle furnace (LF) refining furnace. The Al–Mg–Ca alloy was chosen as dearseicating agent, The industrial test about dearsenication in the molten steel show: the dearsenication in the molten steel can be realized in the LF furnace, the sulfur and calcium content in the molten steel is restrictive factor for dearsenication under industrial condition; the control level of sulfur and calcium in molten steel is put forward to ensure the effect of dearsenication. The sulfur content in molten steel must be reduced to less than 0.01% before dearsenicating in LF furnace, the calcium should be higher than 0.0055% after adding Al–Mg–Ca alloy.

Human brain bank is the foundation for neurology and neuroscience, which provides research materials for medical scientists to explore what happen in human brains. Through voluntary postmortem brain tissue donation, brain bank collects, classifies, stores and distributes brain tissue samples for researchers with appropriate research proposals, so as to facilitate researchers to conduct human brain research. History showed that the act of brain only autopsy distinguished neurology as a distinct discipline. The emerges of brain banking accompanied with the advances of neurology and neuroscience. It facilitates the development of neurology from neuropathological examination feedback about the clinical presentations of the brain donor, plays an important role in the definition of novel neurological diseases, and also makes an extraordinary contribution to the disease mechanisms and novel therapeutic discoveries. This manuscript elaborated the history, current situation, and the impacts of human brain banking on current neurology. Furthermore, we discussed about the opportunities and challenges of brain banking in China. DOI:10.3969/j.issn.1672⁃6731.2020.10.012

The perihematomal edema (PHE) after intracerebral hemorrhage (ICH) is one of the manifestations of secondary brain injury. It is generally believed that the formation of PHE is due to the destruction of blood-brain barrier (BBB) after ICH, which in turn leads to the formation of vasogenic edema. At present, the methods for quantitatively evaluating the permeability of BBB include imaging evaluation and biological marker evaluation, both of which can be used as an important way to study the relationship between BBB and PHE. The ultimate goal of studying the relationship between BBB destruction and PHE is to find treatments that can prevent BBB destruction and reduce PHE after ICH. DOI: 10.3969/j.issn.1672-6731.2018.11.004