Multi-generational asexual reproduction of Gastrodia elata Bl. will cause seedling species degeneration. Sexual reproduction of Gastrodia elata Bl. seed is an effective method to solve the problem of ...degeneration. The development of Gastrodia elata Bl. seeds cannot be separated from the germination fungus. However, there are few strains of germination fungus in production, and there is also the problem of species degradation in application for many years. It is very important for the sexual reproduction of Gastrodia elata Bl. to isolate more new strains of excellent germination fungus from the origin. This study used the Gastrodia elata Bl. f. glauca S. chow seeds germination vegetative propagation corms capture method to isolate its symbiotic germination fungus, and comprehensively identified the species of germination fungus by colony morphology, ITS, sporocarps regeneration and germination function, and compared the growth characteristics and germination ability with other germination fungus (Mycena purpureofusca, Mycena dendrobii and Mycena osmundicola). The germination fungus was isolated from the vegetative propagation corms of Gastrodia elata Bl. f. glauca S. chow seeds and named GYGL-1. After comprehensive identification, GYGL-1 was Mycetinis scorodonius. Compared with other germination fungus, GYGL-1 has fast germination speed, vigorous growth, and high germination ability for Gastrodia elata Bl. f. glauca S. chow seeds. Innovated the isolation method of Gastrodia elata Bl. seeds germination fungus, obtained the regenerated sporocarps of the germination fungus, and discovered that Mycetinis scorodonius has a new function of germinating Gastrodia elata Bl. f. glauca S. chow seeds, enriching the resource library of Gastrodia elata Bl. germination fungus.
The inherent hysteresis of magnetorheological fluid dampers is one of the main reasons which limit their applications. The hysteresis mainly caused from two aspects. One part of the hysteresis is ...between the damping force and the piston velocity, which induced from the friction force of the damper, the compressibility of the fluid, rheological behavior etc. Another part of the hysteresis is between the damping force and the control current, which induced from the ferromagnetic materials inside the MR fluid damper. The ferromagnetic hysteresis of the MR fluid damper has been paid little attention to for a long time. Currently, the MR fluid damper is applying to the field of high velocity or shock and impact loadings where ferromagnetic hysteresis reduces the performance of the control current which leads to worse performances of vibration or buffer. Hall sensors are embedded to the MR fluid damper in this paper so that the magnetic flux density of the damping channels can be measured in real time. The hysteresis loops of the damping channels are obtained by measuring the relationships of the magnetic flux densities and the control currents. Furthermore, a Jiles-Atherton (J-A) hysteresis model based on differential equations for the MR fluid damper is established. The J-A hysteresis model is according to the domain-wall theory so that it has clear physical meaning with a small number of parameters. The hysteresis model is simulated utilizing MATLAB/SIMULINK. The particle swarm optimization (PSO) is adopted to identify the parameters of the J-A hysteresis model. The results show that the hysteresis loops identified by PSO is more similar to the measured hysteresis loops compared with the traditional parameter identification method. The research in this paper on the characteristic and model of the ferromagnetic hysteresis of the MR fluid damper is benefit to decrease or eliminate the effects of hysteresis which can improve the performances of the MR fluid dampers.
In the magnetorheological (MR) impact buffer system, the internal or external disturbance of the MR damper is one of the main factors that affect the buffer performance of the system. This study aims ...to suppress or eliminate the influence of the disturbance of the MR damper. The continuous terminal sliding mode control (CTSMC) strategy with a high gain has a strong antidisturbance ability. However, the high gain may cause fluctuation of the damping force of the system. Therefore, a composite control strategy of sliding mode active disturbance rejection control (ADRC) based on an extended state observer (ESO) is proposed in this study. The total disturbance of the system is estimated by the ESO in real time, and the estimated disturbance is used as a feedforward compensation to the controller to reduce the influence of disturbance on the system. The gain of the CTSMC law of the closed-loop system can be reduced. In addition, the Lyapunov stability criterion is used to ensure the stability of the proposed controller. In order to verify the performance of the proposed CTSMC controller on response speed, overshoot, and hysteresis suppression ability, the window function, square wave function, and multistep function are given as the inputs of the control system. To verify the performance of the proposed sliding mode ADRC for the MR impact buffer system, the mechanical model and the control model are established and simulated using MATLAB/Simulink. The simulation results show that the CTSMC controller has the fastest response time and no overshoot and can suppress the hysteresis nonlinearity of the MR device compared with the open-loop control, PID control, and fractional order PID control. The MR impact buffer system with the sliding mode ADRC obtained the minimum peak value of 4350N within the permitted buffer displacement range compared with the other three traditional control methods. That means the proposed control method in this study has the advantage on buffer performance for the MR impact buffer system.
The hysteresis non-linearity of a magnetorheological (MR) fluid damper is one of the main reasons to restrict it to be widely used in shock buffering fields. This research aims to reduce or eliminate ...the effect of the magnetic hysteresis of the MR damper. A magnetic hysteresis compensation control method is proposed and verified in this paper. Jiles-Atherton (J-A) model is employed to descript the hysteresis non-linearity between the adjustable damping force and the actual magnetic induction intensity in the effective damping channel of the MR fluid damper. The simulation of the magnetic compensation control system is performed to evaluate the effectiveness of the proposed method and the employed model. In order to obtain the actual magnetic induction intensity, a MR fluid damper embedded in a Hall sensor is designed and manufactured. The experimental study is carried out to verify the proposed PID control of hysteresis compensation method. Both the simulation results and the experimental results show the MR fluid damper employed proposed hysteresis compensation method with PID control can almost completely eliminate the effect of hysteresis under both low frequency and high frequency input. The experimental results indicate the hysteresis control system of MR fluid damper is of good dynamic performance which make it suitable for the shock buffering system. At last, a simulation model of the MR-damper-based impact buffer system with hysteresis compensation control is established to verify the buffer effect of the system. The output damping force of the MR impact buffer system indicates the buffer performance has been improved by employing the magnetic hysteresis compensation control method.
In the micro-strapdown inertial navigation systems of Internet of Things, modeling and filtering of gyro random noise are a useful approach to reducing sensor error and enhancing navigation accuracy. ...Time series is a popular choice for the gyro random noise modeling process. This paper contains two parts to research the modeling methods of gyro random noise. In the first part, for the problem that conventional autoregressive (AR) modeling methods for fiber optic gyro random noise require mass data due to the slow convergence speed of parameter estimation, furthermore, these methods do not perform well if there are too few samples (e.g., less than 3000), and a novel AR modeling method based on the adaptive Kalman filter is proposed. The proposed method can work with smaller sample sizes due to its rapid parameter estimation convergence speed; its algorithm also yields very precise results. These advantages make it well-suited to applications that require a fast AR modeling method for gyro random noise. In the second part, an experiment reveals that the random noise characteristic of some micro-electromechanical systems gyros is adapted to the moving average (MA) model. However, from the available literature, research on a gyro random noise modeling method based on an MA model is very rare. Therefore, we discuss and analyze two MA modeling methods for gyro random noise and give the comparisons between their modeling results.
Magnetorheological (MR) absorbers in the artillery recoil systems are usually used to dissipate the impact energy as much as possible and reduce the recoil force transmitted to the artillery ...carriage, while the firing stability of artillery during the buffer process is rarely considered. In this paper, we analyzed the firing stability characteristics of the fixed artillery and the field artillery systems and established corresponding mechanical models. Then, we proposed the ideal recoil F–v curves of these two kinds of artillery, respectively. The “platform effect” of recoil curve was taken as the recoil force control target of the fixed artillery, while based on the firing stability, the linear segmented recoil curve was drawn up as the ideal recoil buffer control target of the field artillery. To verify the feasibility and controllability of the designed multi-stage MR absorber in two kinds of recoil buffer system, the impact tests were conducted under different current loadings. The test results show that the designed MR absorber can realize different buffer control effects by changing the input current, but the ideal “platform effect” recoil curve of the fixed artillery cannot be completely realized due to small controllable damping force output. In the field artillery recoil system, the MR absorber can realize ideal recoil buffer control in the range of 0°–25° firing angles.
In this study, a novel magnetorheological brake with multi-pole and dual-gap configuration is presented to increase not merely the torque output but also the range of controllable transmission torque ...while maintaining a compact structure. In addition, the proposed magnetorheological brake design features several individual coils, and lower power consumption for a desired torque output could be obtained by properly controlling the input currents in those coils. Theoretical research has been done in order to reveal the relationship between the novel structure and the output torque and obtain the mathematical formulas of the output torque. Then, based on the theoretical research, finite element analysis was performed to optimize the structure, analyze the magnetic field distribution, and evaluate the capability of the designed magnetorheological brake. Finally, an optimization was performed to obtain the minimum power consumption for a desired torque. The results show that the proposed magnetorheological brake can generate a considerable torque density in its dimensions while maintaining controllable power consumption by individual input currents.
A novel magnetorheological (MR) damper with a multistage piston and independent input currents is designed and analyzed. The equivalent magnetic circuit model is investigated along with the relation ...between magnetic induction density in the working gap and input currents of the electromagnetic coils. Finite element method (FEM) is used to analyze the distribution of magnetic field through the MR fluid region. Considering the real situation, coupling equations are presented to analyze the electromagnetic-thermal-flow coupling problems. Software COMSOL is used to analyze the multiphysics, that is, electromagnetic, thermal dynamic, and fluid mechanic. A measurement index involving total damping force, dynamic range, and induction time needed for magnetic coil is put forward to evaluate the performance of the novel multistage MR damper. The simulation results show that it is promising for applications under high velocity and works better when more electromagnetic coils are applied with input currents separately. Besides, in order to reduce energy consumption, it is recommended to apply more electromagnetic coils with relative low currents based on the analysis of pressure drop along the annular gap.
This article presents an optimal control strategy with fuzzy compensation for a magnetorheological fluid damper in control of a full-scale gun recoil buffering system. The novel control strategy ...combines the optimal control, in which no measurement feedback needed and the fuzzy logic control which is independent of any theoretical model. The theoretical optimal controllable damping force rule, as a fail-safe control output when the measurement system fails under the extreme condition of impact loading, is derived from the analytical solution of the kinematic equation of the recoil system with a magnetorheological damper. A one-dimensional fuzzy controller and a two-dimensional fuzzy controller are both designed and performed by simulation in order to evaluate the effectiveness of fuzzy control strategy as compensation in the magnetorheological recoil system. A magnetorheological damper for the real firing impact loading is designed and manufactured. Furthermore, an experimental study is carried out to evaluate the optimal control strategy with fuzzy compensation for magnetorheological damper on a firing test rig. The experimental results indicate that the proposed control strategy in this article obtains better buffering performance comprehensively compared with the conventional control strategies.
Intelligent farming machines are becoming a new trend in modern agriculture. The intelligence and automation allow planting to become data-driven, leading to more timely and cost-effective production ...and management of farms and improving the quality and output of farm products. This paper presents a proposal for developing a type of intelligent tea picking machine based on active computer vision and Internet of Things (IoT) techniques. The intelligent tea picking machine possesses an active vision system for new tip positioning and can automatically implement tea picking operation in the natural environment. The active vision system provided with a cross-light path of projection and camera is designed according to the actual characteristics of picking surface, where new tips can be recognized by referring to the color factor and their height information is easily acquired by fringe projection profilometry. Furthermore, the machine attaches wireless communication equipment to transmit the real-time status of the tea picking process to an intermediary platform and eventually to the Internet for extensive data analysis. The data such as color factor and quantity of new tips collected through IoT can be used for different quality and production evaluations. The focus of this paper can promote the automation and intelligence of tea pickers and agricultural machinery.
PDF
