摘要：A novel air-powered twin-rotor piston engine(ATPE) utilizing a differential velocity driving mechanism to achieve a high output torque was *** ATPE had eight separated rotary cylinders which can dynamically enlarge the engine displacement as a result of the special driving mechanism,which was named dynamic volume *** mathematical model of ATPE comprising a dynamic model and a thermodynamic model was established under the assumption of no mechanical *** model was numerically simulated in *** results show that shortage of low output torque confusing traditional air-powered engines can be *** average output torque sharply increases to 100 N·m,which is about three times that of traditional air-powered engines with equal cylinder displacement under the pressure of 0.6 MPa at 480 r/*** can be used to drive vehicles directly without transmission box,therefore the energy transfer efficiency of ATPE can be ***,benefitting from the novel gas distribution system,the engine shows an ability in self-adjusting under different *** arrangements of air ports automatically adjust the open interval of air ports according to the load,which may simplify the speed control system.

摘要：A robust unified controller was proposed for wheeled mobile robots that do not satisfy the ideal rolling without slipping *** trajectory tracking and posture stabilization were achieved in a unified *** design procedure was based on the transverse function method and Lyapunov redesign *** Lie group was also introduced in the *** left-invariance property of the nominal model was firstly explored with respect to the standard group operation of the Lie group SE(2).Then,a bounded transverse function was constructed,by which a corresponding smooth embedded submanifold was *** the aid of the group operation,a smooth control law was designed,which fulfills practical tracking/stabilization of the nominal *** additional component was finally constructed to robustify the nominal control law with respect to the slipping disturbance by using the Lyapunov redesign *** design procedure can be easily extended to the robot system suffered from general unknown but bounded *** were provided to demonstrate the effectiveness of the robust unified controller.

摘要：Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential appli- cations such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transforma- tion function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers.

摘要：In this paper we design the following two-step scheme to estimate the model parameter ω0 of the quantum system: first we utilize the Fisher information with respect to an intermediate variable v = cos(ω0 t) to determine an optimal initial state and to seek optimal parameters of the POVM measurement operators; second we explore how to estimate ω0 from v by choosing t when a priori information knowledge of ω0 is available. Our optimal initial state can achieve the maximum quantum Fisher information. The formulation of the optimal time t is obtained and the complete algorithm for parameter estimation is presented. We further explore how the lower bound of the estimation deviation depends on the a priori information of the model.

摘要：This paper addresses double-loop robust tracking controller design of the miniaturized linear motor drive precision stage with mass and damping ratio uncertainties. As an inner-loop, a disturbance observer （DOB） is employed to suppress exogenous low frequency disturbances such as friction and cutting force. To further eliminate the residual disturbance and to guarantee the robust tracking to the reference input, μ-synthesis outer-loop controller is designed. For eliminating the steady state error, a technique is proposed to design the μ-synthesis outer-loop controller with an integrator. A guideline to select the bandwidth of the Q-filter in the DOB is provided. Simulations using a model of a prototype micro-milling machine indicate that the proposed outer-loop synthesis scheme is superior to the H∞ suboptimal control in disturbance rejection performance and steady state tracking performance. Furthermore, it is shown experimentally that the proposed double-loop robust tracking controller improves the tracking performance of the stage by 29.6% over PID control with a DOB inner-loop.

摘要：The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid, which bring difficult to the stability of the AUV＇s control system. In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV＇s attitude control and the disturbances caused by the external marine environment, a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed, which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions. In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV＇s attitude control, the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects. Then the impacts of system parameters, rudder actuator＇s constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer. The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV＇s attitude control through dynamically adjusting the sliding boundary layer thickness. The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator, which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.

摘要：Valves are widely used in various working conditions for their flow control functions,and the cavitation inside valves has been investigated owing to its harm to the valve itself and the connecting downstream *** paper presents a comprehensive review of the progress that has been achieved in the past years about cavitation in valves including both mechanical heart valves and control *** review is divided in the following parts,namely the location where there is a high possibility of the occurrence of cavitation,the parameters that affect cavitation intensity,and the methods to minimize cavitation *** should be noticed that although simulation has been widely used,advanced experiments are still needed in order to obtain accurate analysis of cavitation in valves and the cavitation model still needs to be improved.

摘要：On the basis of analysis of the present roofbolter’s structures, the pneumatic vane motor roofbolter was proposed and researched. Structure principle of MFT 80Y type pneumatic vane motor roofbolter was expounded, a new project of the rotary shearing mechanism with integrating pneumatic vane motor with epicyclic reduction gear unit was carried out, the mathematical model for optimum design of the rotary shearing mechanism was set up, and the optimum design for the rotary shearing mechanism was made by MATLAB Optimization Toolbox. Finally, performance of MFT 80 type pneumatic vane motor roofbolter made with optimum method and the on site experiment were introduced.

摘要：Tracheal stents are an important form of treatment for benign or malignant central airway ***,the mechanical behavior of current tracheal stents is significantly different from that of the native trachea,which leads to a variety of serious *** this study,inspired by the structure of the native trachea,a wavy non-uniform ligament chiral tracheal stent is proposed,in which J-shaped stress-strain behavior and negative Poisson's ratio response are achieved by replacing the tangential ligament of tetrachiral and anti-tetrachiral hybrid structure with a wavy non-uniform *** the combination of theoretical analysis,finite element analysis and experimental tests,a wide range of desired J-shaped stress-strain curves are explored to mimic the native porcine trachea by tailoring the stent ***,the negative Poisson’s ratio and auxetic diameter curves versus axial strain of the stent are also studied in detail,thus contributing to the enhancement of cross-section ventilation and reducing the migration of the *** novel tracheal stent with a unique microstructure shows a potential to perfectly match the physiological activities of the native trachea and thereby reduce potential complications.

摘要：Touch-sensitive screens are crucial components of wearable *** such as reduced graphene oxide(rGO),carbon nanotubes(CNTs),and graphene offer promising solutions for flexible touch-sensitive ***,when stacked with flexible substrates to form multilayered capacitive touching sensors,these materials often suffer from substrate delamination in response to deformation;this is due to the materials having different Young’s modulus *** results in failure to offer accurate touch screen *** this work,we demonstrate an induced charge-based mutual capacitive touching sensor capable of high-precision touch *** is enabled by electron trapping and polarization effects related to mixed-coordinated bonding between copper nanoparticles and vertically grown graphene ***,we used an electron cyclotron resonance system to directly fabricate graphene-metal nanofilms(GMNFs)using carbon and copper,which are firmly adhered to flexible *** being subjected to 3000 bending actions,we observed almost no change in touch *** screen interaction system,which has a signal-to-noise ratio of 41.16 dB and resolution of 650 dpi,was tested using a handwritten Chinese character recognition trial and achieved an accuracy of 94.82%.Taken together,these results show the promise of touch-sensitive screens that use directly fabricated GMNFs for wearable devices.