Gate-Voltage-Modulated Spin Precession in Graphene/WS2 Field-Effect Transistors

Transition metal dichalcogenide materials are studied to investigate unexplored research avenues, such as spin transport behavior in 2-dimensional materials due to their strong spin-orbital interaction (SOI) and the proximity effect in van der Waals (vdW) heterostructures. Interfacial interactions between bilayer graphene (BLG) and multilayer tungsten disulfide (ML-WS2) give rise to fascinating properties for the realization of advanced spintronic devices. In this study, a BLG/ML-WS2 vdW heterostructure spin field-effect transistor (FET) was fabricated to demonstrate the gate modulation of Rashba-type SOI and spin precession angle. The gate modulation of Rashba-type SOI and spin precession has been confirmed using the Hanle measurement. The change in spin precession angle agrees well with the local and non-local signals of the BLG/ML-WS2 spin FET. The operation of a spin FET in the absence of a magnetic field at room temperature is successfully demonstrated.

Study on free oscillations of a micromechanical gyroscope taking into account the nonorthogonality of the torsion axes

Introduction. The paper is devoted to the study on free oscillations of the sensing element of a micromechanical R-Rtype gyroscope of frame construction developed by the Kuznetsov Research Institute of Applied Mechanics, taking into account the nonorthogonality of the torsion axes. The influence of the instrumental manufacturing error on the accuracy of a gyroscope on a movable base in the case of free oscillations is studied. The work objective was to improve the device accuracy through developing a mathematical model of an R-R type micromechanical gyroscope, taking into account the nonorthogonality of the torsion axes, and to study the influence of this error on the device accuracy. The urgency of the problem of increasing the accuracy of micromechanical gyroscopes is associated with improving the accuracy of inertial navigation systems based on micromechanical sensors.Materials and Methods. A new mathematical model that describes the gyroscope dynamics, taking into account the instrumental error of manufacturing the device, and a formula for estimating the error of a gyroscope, are proposed. The dependences of the state variables obtained from the results of modeling and on the basis of the experiment are presented. Methods of theoretical mechanics and asymptotic methods, including the Lagrange formalism and the Krylov-Bogolyubov averaging method, were used in the research.Results. A new mathematical model of the gyroscope dynamics, taking into account the nonorthogonality of the torsion axes, is developed. The solution to the equations of small oscillations of the gyroscope sensing element and the estimate of the precession angle for the case of a movable base are obtained. A comparative analysis of the developed model and the experimental data obtained in the case of free oscillations of the gyroscope sensing element with a fixed base is carried out. The analysis has confirmed the adequacy of the constructed mathematical model. Analytical expressions are formed. They demonstrate the fact that the nonorthogonality of the torsion axes causes a cross-influence of the amplitudes of the primary vibrations on the amplitudes of the secondary vibrations of the sensing element, and the appearance of an additional error in the angular velocity readings when the gyroscope is operating in free mode.Discussion and Conclusions. The results obtained can be used to improve the device accuracy using the algorithm for analytical compensation of the gyroscope error and the method for identifying the mathematical model parameters.

Energy map and effective metric in an effective-one-body theory based on the second-post-Minkowskian approximation

Effective-one-body (EOB) theory was originally proposed based on the post-Newtonian (PN) approximation and plays an important role in the analysis of gravitational wave signals. Recently, the post-Minkowskian (PM) approximation has been applied to the EOB theory. The energy map and the effective metric are the two key building blocks of the EOB theory, and in PN approximation radial action variable correspondence is employed to construct the energy map and the effective metric. In this paper, we employ the PM approximation up to the second order, and use the radial action variable correspondence and the precession angle correspondence to construct the energy map and the effective metric. We find that our results based on the radial action variable correspondence, are exactly the same with those obtained based on the precession angle correspondence. Furthermore, we compare the results obtained in this work to the previous existing ones.

Light Speed Invariant Solution and Its Enlightenment of Field Equation of General Relativity

A systematic examination of the basic theory of general relativity is made, the meaning of coordinates again is emphasized, the confusion caused by unclear meaning of coordinates in the past is corrected, and the expression of the theory is made more accurate. Firstly, the equation of Einstein’s gravitational field is solved in the usual coordinate system, the existence of light speed invariant solution in the spherically symmetric gravitational field is proved, and in the same time, the solution is determined. It turns out that black holes are not an inevitable prediction of general relativity. The more exact formulas for calculating the curvature of light on the surface of the Sun and the precession angle of the orbit of Mercury are given, and the convergence of general relativistic gravity and special relativistic mechanics under the weak field approximation is realized. Finally, it is shown that the coupling coefficient of the gravitational field equation is not unique. Modifying this coefficient is an ideal project to eliminate the singularities of general relativity on the condition keeping the field equation concise and elegant, and moreover, it reveals that dark matter and dark energy are the negative energy field in the matter, the expansion of the universe is the appearance of the gradual formation of galaxies in accordance with fractal rules, not only the space between galaxies is expanding but also the galaxies themselves are also expanding, new matter is continuously generated in the celestial bodies, for the first time, the unity of fractal geometry and cosmic dynamics of general relativity is realized, and the formation and evolution of galaxies are brought into the fractal generation mode. This is a living and vivacious universe in which all aspects are gradually strengthening, in sharp contrast to the dying universe under the current cosmological framework.

Movement Modeling and Control for Robotic Bonnet Polishing

The spin axis of bonnet tool maintains a constant angle (precession angle) with the normal of polishing point in polishing. In this paper, a controlled model was established on robotic machining platform to polish large diameter axisymmetric aspheric optics. Based on the transformation relationship in spatial coordinate system, the relationships between workpiece coordinate system, polishing point local coordinate system and the bonnet tool coordinate system were set up respectively. So that the movement model of bonnet precession polishing was obtained. What’s more, the efficiency optimal control was added to the movement model. the trajectories and poses of the polishing were determined, and the change of robot linkage angle difference was obtained. Finally, the precession movement model and the control algorithm were verified by the simulation in the Robotstudio, an offline simulation software and experiment for plane component.

Establishment of energy consumption model and multi-objective optimal control method of 6-DOF robotic crusher

In order to optimize the real-time crushing effect of 6-DOF robotic crusher, a model of energy consumption and a multi-objective optimization control method for 6-DOF robotic crusher are proposed. In optimization function, the optimization objective are total energy consumption, mass fraction of crushed products below 12 mm, energy consumption ratio, and throughput, and optimization variables are position of suspension point, rotational speed and precession angle of the moving cone. Among them, the function of total energy consumption and effective energy consumption is established and the function of total energy consumption is verified in this paper. The function of mass fraction of crushed products below 12 mm is based on previous research. Taking the full load working condition and chamber size of PYGB1821 crusher as an example. The solution of optimization is obtained. Compared with the traditional cone crusher under the same feed size distribution and chamber size, each objective can be effectively optimized, which can effectively reduce energy consumption and increase the crushing efficiency. This method is universal and can be used for the design and control of other crushing equipment.

The Light Speed Invariant Solution of the Field Equation of General Relativity

The fundamental concepts of general relativity are systematically rearranged. Firstly, the equations of Einstein’s gravitational field are solved in the usual sphere coordinate system, and the existence of the invariant solution of the speed of light in the spherically symmetric gravitational field is proved, also determine the solution. It is revealed that black holes are not the inevitable prediction of general relativity. Black holes do not exist, and the so-called gravitational waves sent by black holes need to be explained in other ways. Correcting the conceptual confusion caused by unclear radial coordinates in the past, two more accurate formulas for calculating the curvature of light on the surface of the sun and the precession angle of the orbit of Mercury are given. Finally, discuss that the coupling constant of the gravitational field equation needs to be modified, which is a shortcut to eliminate various singularities of general relativity. It is proved that the celestial bodies and galaxies expand with the expansion of the universe, and new matter is generated continuously in the celestial bodies, which provides a theoretical basis for the fractal generation model of galaxy formation.

Angular distribution and asymmetries in the decay of the polarized charmed baryon Λc+ → K−Δ++ → K−pπ+

Angular distribution of the final particles in the decay [Formula: see text] of the polarized charmed baryon is discussed. Asymmetries are proposed that allow for determination of the components of the [Formula: see text] polarization vector. The precession angle of the polarization in the process of baryon channeling in a bent crystal is directly related to these asymmetries. The decay rate and asymmetry parameter for the [Formula: see text] decay are calculated in the pole model and compared with experiment.

Constrained H∞ control of gyroscopic ship stabilization systems

We suggest a constrained [Formula: see text] control scheme for gyroscopic marine vehicle stabilization systems with output and control constraints. The [Formula: see text] performance is used to measure the roll angle reduction of the vessel relative to wave disturbances in regular beam seas. Time-domain constraints, representing requirements for precession angle of gyroscopes and for actuator saturation, are captured using the concept of reachable sets and state-space ellipsoids. A state feedback solution to the constrained [Formula: see text] stabilization control problem is proposed in the framework of linear matrix inequality optimization and multiobjective control. This approach can potentially achieve the best possible vessel comfort with respect to roll motion by allowing constrained variables free as long as they remain within given bounds. Analysis and simulation results for roll dynamics of the vessel coupled with the gyroscopic actuator control system show possible improvements on roll motion stabilization while respecting time-domain hard constraints.

An Underwater Vector Propulsion Device Based on the RS+2PRS Parallel Mechanism and Its Attitude Control Algorithm

In order to overcome the disadvantages of some existing autonomous underwater vehicles (AUVs), such as actuator extraposition and degree-of-freedom (DOF) redundancy, a 2-DOF vector propeller propulsion system with built-in actuator based on the deficient DOF parallel mechanism is proposed. The RS+2PRS (Revolute-Spherical+ Prismatic-Revolute-Spherical) parallel mechanism is used as the main structure, and the driving parts are placed in the interior of the AUV cabin, which is beneficial to the sealing and protection of the propulsion system. In addition, the motion parameters decoupling shows that the two independent parameters are the precession angle and the nutation angle of the propeller installation platform. Therefore, the attitude control algorithm uses two prismatic joints as driving units to establish the nonlinear mapping model with the two Euler attitude angles. In the end, the simulation analysis and the real device are used to verify the feasibility of the attitude control algorithm and the in situ adjustment function of the propeller, which lays the theoretical foundation for engineering applications in the future.