数控机床光栅尺部分故障实例分析

本文通过数控机床的故障实例，分析了光栅故障现象及原因和解决的办法。     

Stabilization of uncertain networked control systems with actuator saturation and probabilistic cyberattacks

This paper investigates the stabilization of uncertain networked control systems (NCSs) with actuator saturation and cyberattacks. The cyberattacks are governed by a set of independent random variables satisfying Bernoulli distribution. To relieve the network bandwidth load effectively, an event-triggered communication strategy is proposed. By employing Lyapunov stability theory and stochastic analysis techniques, a stability criterion is obtained for the system with actuator saturation and cyberattacks. Moreover, the desired controller gain is derived by solving some matrix inequalities. Finally, the validity and applicability of the criteria are verified through numerical examples.     

A new method using feature extraction for identifying paddy rice species for quality seed selection

The purpose of this work was to explore a new feature extraction method for classifying paddy seeds using a feature extraction algorithm to achieve the area ratio, horizontal–slant and front–rear angles and find whether the proposed features have high discriminating power. Another objective was to find the smallest feature set that can ensure highly accurate recognition of seeds. A total of a 100 image features were extracted, and features having significant discriminating power were identified based on the analysis of variance (ANOVA). From the 100 features, 14 features were found to have high discriminating power and from these features, six were selected as the proposed features. Experimental results show that the proposed features and removal of redundant features enhanced the discriminating power of the feature set, and that the proposed features have an excellent discriminating property for seeds. The presented features resulted in the highest classification accuracy (98.8%) when compared to other methods.     

Synchronization of stochastic complex dynamical networks under self‐triggered control

In this paper, we investigate the mean square exponential synchronization of stochastic nonlinear complex dynamical networks with or without communication delays. A new self‐triggered mechanism is proposed to reduce the amount of communication while preserving the desired system's performance. Under this mechanism, the next sampling instant is dynamically determined by the latest transmitted state rather than the online detection of the event‐triggered condition. Meanwhile, we show that the inter‐execution time of self‐triggered mechanism is bounded by a strictly positive constant, and the maximal allowable delay of the underlying system is given. A simulation is provided to illustrate the effectiveness of the proposed self‐triggered scenario. Copyright © 2016 John Wiley & Sons, Ltd.     

Creation and control of high-dimensional multi-partite classically entangled light

Vector beams, non-separable in spatial mode and polarisation, have emerged as enabling tools in many diverse applications, from communication to imaging. This a...     

Determination of the Exciton Binding Energy Using Photothermal and Photoluminescence Spectroscopy

In this paper, experimental photoluminescence (PL) and piezoelectric photothermal (PPT) spectra of selected II–VI binary crystals are presented and analyzed. The quantitative analysis of the photothermal spectra was performed using a modified and extended Jackson–Amer model. The values of the bandgap energies of investigated semiconductors were computed from the PT amplitude and phase spectra. From the temperature dependence of the exciton emission so-called “excitonic energy gaps” have been determined. It follows from the theory that the exciton binding energy is the difference of these two values of energy gaps derived from PPT and PL spectroscopy.     

Effect of nBaCO3 on mechanical,thermal and morphological properties of isotactic PP-EPDM blend

Isotactic polypropylene (iPP): ethylene propylene diene monomer (EPDM) blend is one of the most suited compatible and miscible blends. The blends of iPP and EPDM (80:20) filled with BaCO₃ nanoparticles (0.5, 1.5, 2.5 and 3 wt%) were prepared on Brabender Plasticorder, which was then subjected to injection molding to get dumbbell-shaped specimens. Meanwhile, BaCO₃ nanoparticles (nBaCO₃) were prepared using ultrasonic cavitation technique. The size and shape of nBaCO₃ particle was confirmed using transmission electron microscope and found to be capsule shape of diameter ~40–60 nm with aspect ratio (l/d) of 2.2–2.5. The reduction in particle size of nBaCO₃ leads to formation of uniform suspension. The solution was kept as such for long time so as to nullify the charges developed over the surface of nanoparticles. The mechanical properties of nBaCO₃-reinforced iPP-EPDM blends were studied using universal testing machine and impact tester. Moreover, thermal properties were studied using flammability tester, vicat softening temperature, thermo gravimetric analyzer and differential scanning calorimeter (DSC). Dispersion of nBaCO₃ in iPP-EPDM matrix was studied using scanning electron microscope and X-ray diffractometer. The mechanical and thermal properties of iPP-EPDM/nBaCO₃ blends were found to be improved significantly with increasing amount of nBaCO₃ up to 2.5 wt%, which is due to good compatibility in between iPP and EPDM with uniform dispersion of nBaCO₃. Moreover, due to agglomeration at 3 wt% loading of nBaCO₃ few of the properties found to be decreased marginally.     

Simultaneous Enhancement of Fracture Toughness and Unipolar Strain in Pb(Zr,Ti)O3‐ZrO2 Composites Through Composition Adjustment

The influence of second phase zirconia particles on the electrical properties and fracture behavior of various polycrystalline soft Pb(Zr_1?xTi_x)O₃ (PZT) compositions was investigated. PZT composites with yttria‐stabilized tetragonal zirconia particles exhibited enhanced crack resistance in comparison to monolithic compositions, regardless of the PZT composition. The addition of zirconia, however, was found to change the PZT composition through the diffusion of zirconium, resulting in variations in the observed piezoelectric and ferroelectric responses. Through the tailoring of the PZT matrix composition, the large electromechanical response and enhanced fracture toughness could be retained. The variation in both small and large signal properties is contrasted to fracture results and crystal structure changes, as determined by X‐ray diffraction.     

HIFE-haptic interface for finger exercise

A haptic device with two active degrees of freedom and a tendon-driven transmission system was designed, built, and tested. It was constructed as a mechanism with a small workspace that envelops a finger workspace and can generate forces up to 10 N, suitable for finger exercise. Kinematic and dynamic model equations of the haptic device are presented in the paper. The control strategies, the implementation of the application on a PC, the real-time millisecond-class control environment, running under the MS Widows operating system, and safety mechanisms are described. Also, the duration test for the maximum sustained output force, and validations of accuracy of the output force and the consistency of the followed path, were performed. The performance, accuracy, and safety of the device were found to be very good, which makes the device suitable for rehabilitation purposes.