Compensation method for complex hysteresis characteristics on piezoelectric actuator based on Separated Level-loop Prandtl–Ishlinskii model

Piezoelectric ceramic actuators exhibit nonlinear hysteresis characteristics owing to their material properties. To modify the inverse piezoelectric effect as an ideal linear execution, the classical Prandtl–Ishlinskii (PI) model is usually used for compensation by feedforward control. The PI model compensates well on simple hysteresis characteristics. However, when the output requirements are complex, the PI model demonstrates uneven compensation accuracy on the complex hysteresis characteristics and cannot achieve an accuracy similar to that of simple hysteresis. This paper proposes a simplification of complex hysteresis: Separated Level-loop PI (SLPI) model. First, we use a loop-separation logic algorithm to simplify the complex hysteresis characteristics to obtain hysteresis in the form of single loops with loop levels and vertexes. Second, the hysteresis characteristics of each loop are independently modeled using the PI model. Finally, the inverse model is reconstructed using a rollback method to restore a positive sequence of the feedforward voltage; then, the feedforward voltage is input as a compensation value to achieve higher and more uniform accuracy. Experiments and discussions show that the SLPI model can effectively improve the compensation results of complex hysteresis characteristics; moreover, the average compensation accuracy difference between single hysteresis loops was reduced.

A neural network closure for the Euler-Poisson system based on kinetic simulations

<p style='text-indent:20px;'>This work deals with the modeling of plasmas, which are ionized gases. Thanks to machine learning, we construct a closure for the one-dimensional Euler-Poisson system valid for a wide range of collisional regimes. This closure, based on a fully convolutional neural network called V-net, takes as input the whole spatial density, mean velocity and temperature and predicts as output the whole heat flux. It is learned from data coming from kinetic simulations of the Vlasov-Poisson equations. Data generation and preprocessings are designed to ensure an almost uniform accuracy over the chosen range of Knudsen numbers (which parametrize collisional regimes). Finally, several numerical tests are carried out to assess validity and flexibility of the whole pipeline.</p>

Analytical Study on Tooth Profile of Non-Circular Gear Based on Hobbing Process Simulation

Based on the hobbing process simulation of non-circular gears, a method for obtaining the precise tooth profile and evaluating the undercutting characteristics according to the profile generated after the finite number of envelop is proposed. The profile points formed by different hobbing strategies are compared, then the envelope method with uniform accuracy for all teeth is selected. The formation rule of tooth profile morphology is analyzed, and the pickup method with high convergence rate is proposed. The influences of the envelope number and gear parameters on the tooth profile accuracy are analyzed inductively, and the reasonable number of envelopes for expected accuracy is given. The results show that the tooth profile analysis method based on the hobbing process simulation can accurately acquire all feature points of the tooth profile and analysis the undercutting phenomenon.

Uniformly accurate time-splitting methods for the semiclassical linear Schrödinger equation

This article is devoted to the construction of numerical methods which remain insensitive to the smallness of the semiclassical parameter for the linear Schrödinger equation in the semiclassical limit. We specifically analyse the convergence behavior of the first-order splitting. Our main result is a proof of uniform accuracy. We illustrate the properties of our methods with simulations.

Enigma at the nanoscale: can the NPC act as an intrinsic reporter for isotropic expansion microscopy?

Expansion microscopy is a super-resolution method that allows expanding uniformly biological samples, by increasing the relative distances among fluorescent molecules labeling specific components. The main “enigma” regarding this approach is given by the isotropic behavior at the nanoscale. The present study aims to determine the robustness of such a technique, quantifying the expansion parameters i.e. scale factor, isotropy, uniformity. Our focus is on the nuclear pore complex (NPC), as well-known nanoscale component endowed of a preserved and symmetrical structure localized on the nuclear envelope. Here, we show that Nup153 is a good reporter to quantitatively address the isotropy of the expansion process. The quantitative analysis carried out on NPCs, at different spatial scales, allows concluding that expansion microscopy can be used at the nanoscale with a uniform accuracy in the range of 20 nm. In addition, it is an excellent method for structural studies of macromolecular complexes.

A high-order predictor-corrector method for solving nonlinear differential equations of fractional order

An accurate and efficient new class of predictor-corrector schemes are proposed for solving nonlinear differential equations of fractional order. By introducing a new prediction method which is explicit and of the same accuracy order as that of the correction stage, the new schemes achieve a uniform accuracy order regardless of the values of fractional order