A Method for Recognizing Fatigue Driving Based on Dempster-Shafer Theory and Fuzzy Neural Network

This study proposes a method based on Dempster-Shafer theory (DST) and fuzzy neural network (FNN) to improve the reliability of recognizing fatigue driving. This method measures driving states using multifeature fusion. First, FNN is introduced to obtain the basic probability assignment (BPA) of each piece of evidence given the lack of a general solution to the definition of BPA function. Second, a modified algorithm that revises conflict evidence is proposed to reduce unreasonable fusion results when unreliable information exists. Finally, the recognition result is given according to the combination of revised evidence based on Dempster’s rule. Experiment results demonstrate that the recognition method proposed in this paper can obtain reasonable results with the combination of information given by multiple features. The proposed method can also effectively and accurately describe driving states

Current-Loop Control for the Pitching Axis of Aerial Cameras via an Improved ADRC

An improved active disturbance rejection controller (ADRC) is designed to eliminate the influences of the current-loop for the pitching axis control system of an aerial camera. The improved ADRC is composed of a tracking differentiator (TD), an improved extended state observer (ESO), an improved nonlinear state error feedback (NLSEF), and a disturbance compensation device (DCD). The TD is used to arrange transient process. The improved ESO is utilized to observe the state extended by nonlinear dynamics, model uncertainty, and external disturbances. Overtime variation of the current-loop can be predicted by the improved ESO. The improved NLSEF is adopted to restrain the residual errors of the current-loop. The DCD is used to compensate the overtime variation of the current-loop in real time. The improved ADRC is designed based on a new nonlinear function newfal(·). This function exhibits enhanced continuity and smoothness compared to previously available nonlinear functions. Thus, the new nonlinear function can effectively decrease the high-frequency flutter phenomenon. The improved ADRC exhibits improved control performance, and disturbances of the current-loop can be eliminated by the improved ADRC. Finally, simulation experiments are performed. Results show that the improved ADRC displayed better performance than the proportional integral (PI) control strategy and traditional ADRC

Speed Control Based on ESO for the Pitching Axis of Satellite Cameras

The pitching axis is the main axis of a satellite camera and is used to control the pitch posture of satellite cameras. A control strategy based on extended state observer (ESO) is designed to obtain a fast response speed and highly accurate pitching axis control system and eliminate disturbances during the adjustment of pitch posture. First, a sufficient condition of stabilization for ESO is obtained by analyzing the steady-state error of the system under step input. Parameter tuning and disturbance compensation are performed by ESO. Second, the ESO of speed loop is designed by the speed equation of the pitching axis of satellite cameras. The ESO parameters are obtained by pole assignment. By ESO, the original state variable observes the motor angular speed and the extended state variable observes the load torque. Therefore, the external load disturbances of the control system are estimated in real time. Finally, simulation experiments are performed for the system on the cases of nonload starting, adding external disturbances on the system suddenly, and the load of system changing suddenly. Simulation results show that the control strategy based on ESO has better stability, adaptability, and robustness than the PI control strategy

Prevalence estimation of ATTRv in China based on genetic databases

Introduction: Amyloid transthyretin (ATTR) is divided into either hereditary (ATTRv) or sporadic (ATTRwt) and ATTRv is a rare hereditary disease transmitted as an autosomal dominant manner. Its global prevalence is traditionally estimated as 5,000 to 10,000 persons. However, it may be underestimated and the exact prevalence of ATTRv in China mainland remains unknown.Methods: The Genome Aggregation database (gnomAD) database (containing 125,748 exomes) and two genomic sequencing databases——China Metabolic Analytics Project (ChinaMAP) (containing 10588 individuals) and Amcarelab gene database (containing 45392 exomes), were integrated to estimate the prevalence of ATTRv in the world and mainland Chinese populations. Pathogenic variants allele frequency and the prevalence of ATTRv was calculated.Results: Six variants, counting 470 alleles, were defined as pathogenic variants in gnomAD. The prevalence of ATTRv in the world population was 57.4/100,000. Two variants (2 allele counts) and 15 variants (34 individuals) were defined as pathogenic variants in the ChinaMAP database and the Amcarelab exome database, respectively. Thus, the estimated prevalence interval of ATTRv in mainland China was 18.9/100,000-74,9/100,000.Conclusion: The present study demonstrated that the previous prevalence was greatly underestimated using traditional methods. Therefore, raising awareness of the disease is essential for recognizing ATTRv in its early stage

Characterization of the Metabolic Fate of Datura metel Seed Extract and Its Main Constituents in Rats

Datura metel L. has been frequently used in Chinese traditional medicine. However, little is known on the chemical composition and in vivo metabolism of its seeds. In this study, using the strategy “chemical analysis, metabolism of single representative compounds, and metabolism of extract at clinical dosage” that we propose here, 42 constituents were characterized from D. metel seeds water extract. Furthermore, the metabolic pathways of 13 representative bioactive compounds of D. metel seeds were studied in rats after the oral administration of D. metel seeds water extract at a clinical dosage (0.15 g/kg). These included three withanolides, two withanolide glucosides, four amides, one indole, one triterpenoid, one steroid, and one sesquiterpenoid, and with regard to phase II metabolism, hydroxylation, (de)methylation, and dehydrogenation reactions were dominant. Furthermore, the metabolism of D. metel seeds water extract provided to rats at a clinical dosage was investigated by liquid chromatography-tandem mass spectrometry based on the above metabolic pathways. Sixty-one compounds were detected in plasma, 83 in urine, and 76 in fecal samples. Among them, withanolides exhibited higher plasma exposure than the other types. To our knowledge, this is the first systematic study on the chemical profiling and metabolite identification of D. metel seeds, including all compounds instead of single constituents

Position control for ball and beam system based on active disturbance rejection control

This paper proposes a new control strategy to the position control of the ball in the ball and beam system by adopting an active disturbance rejection control (ADRC). ADRC is composed of a tracking differentiator (TD), an extended state observer (ESO), a nonlinear state error feedback control law (NLSEF), and a disturbance compensation device (DCD). The ESO observes and tracks the position of the ball and the direct current (DC) servomotor in real time. The total disturbance of the system can be expanded and amplified, and can also be effectively compensated in real time to suppress interferences by the ESO. The procedures of research are as follows. First, the model of the ball and beam system, including the motion equation of the system and the DC servomotor, is established. Second, ADRC is designed and applied to the ball and beam system and the DC servomotor. Third, the control model of the ball and beam system is built on the basis of ADRC. Finally, the ball position of ADRC is simulated and verified. The results show that the ball and beam system based on ADRC exhibits better performance than the proportion integration differentiation controller

Consensus Formation Control and Obstacle Avoidance of Multiagent Systems with Directed Topology

This study addresses the problems of formation control and obstacle avoidance for a class of second-order multiagent systems with directed topology. Formation and velocity control laws are designed to solve the formation tracking problem. A new obstacle avoidance control law is also proposed to avoid obstacles. Then, the consensus control protocol consists of the formation, velocity, and obstacle avoidance control laws. The convergence of the proposed control protocol is analyzed by a redesigned Lyapunov function. Finally, the effectiveness of theoretical results is illustrated by simulation examples. The simulation results show that the formation tracking problem of the given multiagent systems can be realized and obstacles can be avoided under the proposed control protocol

Iterative Learning Tracking Control of Nonlinear Multiagent Systems with Input Saturation

A tracking control algorithm of nonlinear multiple agents with undirected communication is studied for each multiagent system affected by external interference and input saturation. A control design scheme combining iterative learning and adaptive control is proposed to perform parameter adaptive time-varying adjustment and prove the effectiveness of the control protocol by designing Lyapunov functions. Simulation results show that the high-precision tracking control problem of the nonlinear multiagent system based on adaptive iterative learning control can be well realized even when the input is saturated. Finally, the validity of the proposed algorithm is verified by numerical analysis

Camera calibration method based on circular array calibration board

Camera calibration will directly affect the accuracy and stability of the whole measurement system. According to the characteristics of circular array calibration plate, a camera calibration method based on circular array calibration plate is proposed in this paper. Firstly, subpixel edge detection algorithm is used for image preprocessing. Then, according to cross ratio invariance and geometric constraints, the projection point position of the center point is obtained. Finally, the calibration experiment was carried out. Experimental results show that under any illumination conditions, the average reprojection error of the center coordinates obtained by the improved calibration algorithm is less than 0.12 pixels, which is better than the traditional camera calibration algorithm

Studies on Cytotoxic Activity against HepG-2 Cells of Naphthoquinones from Green Walnut Husks of Juglans mandshurica Maxim

Twenty-seven naphthoquinones and their derivatives, including four new naphthalenyl glucosides and twenty-three known compounds, were isolated from green walnut husks, which came from Juglans mandshurica Maxim. The structures of four new naphthalenyl glucosides were elucidated based on extensive spectroscopic analyses. All of these compounds were evaluated for their cytotoxic activities against the growth of human cancer cells lines HepG-2 by MTT [3-(4,5-dimethylthiazo l-2-yl)-2,5 diphenyl tetrazolium bromide] assay. The results were shown that most naphthoquinones in an aglycone form exhibited better cytotoxicity in vitro than naphthalenyl glucosides with IC50 values in the range of 7.33–88.23 μM. Meanwhile, preliminary structure-activity relationships for these compounds were discussed