According to statistic data, machinery faults contribute to largest proportion of High-voltage circuit breaker failures, and traditional maintenance methods exist some disadvantages for that issue. Therefore, based on the wavelet packet decomposition approach and support vector machines, a new diagnosis model is proposed for such fault diagnoses in this study. The vibration eigenvalue extraction is analyzed through wavelet packet decomposition, and a four-layer support vector machine is constituted as a fault classifier. The Gaussian radial basis function is employed as the kernel function for the classifier. The penalty parameter c and kernel parameter δ of the support vector machine are vital for the diagnostic accuracy, and these parameters must be carefully predetermined. Thus, a particle swarm optimizationsupport vector machine model is developed in which the optimal parameters c and δ for the support vector machine in each layer are determined by the particle swarm algorithm. The validity of this fault diagnosis model is determined with a real dataset from the operation experiment. Moreover, comparative investigations of fault diagnosis experiments with a normal support vector machine and a particle swarm optimization back-propagation neural network are also implemented. The results indicate that the proposed fault diagnosis model yields better accuracy and efficiency than these other models.

Cutaneous muscles drive the texture-modulation behavior of cephalopods by protruding several millimeters out of the skin. Inspired by cephalopods, a self-morphing, stretchable smart skin containing embedded-printed electrodes and actuated by Twisted Spiral Artificial Muscles (TSAMs) is proposed. Electrothermally actuated TSAMs are manufactured from inexpensive polymer fibers to mimic the papillae muscles of cephalopods. These spirals can produce strains of nearly 2000% using a voltage of only 0.02 V mm −1 . Stretchable and low-resistance liquid metal electrodes are embedded-printed inside the self-morphing skin to facilitate the electrothermal actuation of TSAMs. Theoretical and numerical models are proposed to describe the embedded printing of low-viscosity Newtonian liquid metals as conductive electrodes in a soft elastomeric substrate. Experimental mechanical tests are performed to demonstrate the robustness and electrical stability of the electrodes. Two smart skin prototypes are fabricated to highlight the capabilities of the proposed self-morphing system, including a texture-modulating wearable soft glove and a waterproof skin that emulates the texture-modulation behavior of octopi underwater. The proposed self-morphing stretchable smart skin can find use in a wide range of applications, such as refreshable Braille displays, haptic feedback devices, turbulence tripping, and antifouling devices for underwater vehicles.

Abstract-The high-frequency method for solving the scattering from homogeneous dielectric objects with electrically large size in half space is presented in this paper. In order to consider the scattering fields of the targets in half space, the half-space physical optics method is deduced by introducing the half-space Green's function into the conventional physical optics method (PO). Combined with the graphical-electromagnetic computing method to read the geometry information of all visible facets, the equivalent currents and the reflection coefficients are utilized to account of the homogenous dielectric objects with half-space physical optics method in half space. The numerical results show that this method is efficient and accurate.

The effect of bubble shape in laser-plasma electron acceleration was investigated. We showed the general existence of an ellipsoid bubble. The electromagnetic field in this bubble and its dependence on bubble shape were determined through theory. The electron-trapping cross-section for different bubble aspect ratios was studied in detail. When the shape of the bubble was close to spherical, the trapping cross-section reached to the maximum. When the bubble deviated from a spherical shape, the cross-section decreased until electron injection no longer occurred. These results were confirmed by particle-in-cell simulation.

BackgroundTo investigate the efficacy and safety of continuous ab interno repairing of traumatic cyclodialysis cleft in severe ocular trauma using a 30-gauge (G) needle.MethodsFifteen patients (15 eyes) with traumatic cyclodialysis cleft admitted to the ocular trauma department of our hospital from July 2014 to December 2018 were included in this study. After the bulbar conjunctiva corresponding to the ciliary body was incised along the corneal limbus, an incision was made along the corneal limbus on the opposite side. A 30G needle with a 10–0 suture entered the anterior chamber from the incision and passed through the ciliary body with clefts and the sclera to fixate the ciliary body on the sclera wall with continuous mattress suture. The best corrected visual acuity (BCVA) and intraocular pressure (IOP) were observed preoperatively and postoperatively. In vivo ultrasound biomicroscopy (UBM) was performed to observe closure of cyclodialysis cleft before and after surgery.ResultsFifteen patients successfully underwent continuous mattress suture for repair of cyclodialysis cleft. No bleeding and suture breakage were reported during surgery. After surgery, the UBM during follow-up showed satisfactory closure of the cyclodialysis cleft. The BCVA and IOP were improved to different degrees. The difference between the preoperative IOP and the postoperative IOP (1 week) was statistically significant (preoperative: 6.49 ± 0.98 mmHg, postoperative: 16.17 ± 4.65 mmHg, t = − 8.43, P < 0.05), and the difference between the preoperative IOP and the postoperative IOP (1 month) was also statistically significant (preoperative: 6.49 ± 0.98 mmHg, postoperative: 14.63 ± 3.63 mmHg, t = − 8.38, P < 0.05). Duration of outpatient follow-up was 3 to 12 months. No complications, including exposed knots, loose sutures, decompensation of corneal endothelium, sympathetic ophthalmia, endophthalmitis and choroidal detachment, were reported.ConclusionContinuous ab interno repairing of traumatic cyclodialysis cleft in severe ocular trauma using a 30G needle is a safe and effective procedure with simple operation, little tissue damage and few complications.

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Vertically aligned single-nanowire is verified to be a unique building block to realize the high-efficiency solar cell beyond Schockley-Queisser limit. We proposed a front-tapered vertically aligned single-nanowire solar cell (V-SNSC) and investigated numerically the possibility of this configuration to improve the photoabsorption efficiency compared to the conventional designs, by using 2.5D full-wave finite-element method. The influences of the feature sizes of aspect ratio, bottom radius, and nanowire length on the light-trapping properties were explored; the detailed field distribution and carrier generation rate were revealed as well based on the theory of dielectric resonant antenna, in order to elucidate the underlying physical mechanism. Results showed that, compared with the cylindrical counterparts, the absorption capability of V-SNSCs could be greatly enhanced by using a front-tapered configuration with less material utilized, and that such a positive effect can be further strengthened by increasing the nanowire length. The proposed configuration provides a promising approach to engineer the photoabsorption in the photovoltaic and other optoelectronic devices.

Sunlight-like lasers that have a continuous broad frequency spectrum, random phase spectrum, and random polarization are formulated theoretically. With a sunlight-like laser beam consisting of a sequence of temporal speckles, the resonant three-wave coupling that underlies parametric instabilities in laser–plasma interactions can be greatly degraded owing to the limited duration of each speckle and the frequency shift between two adjacent speckles. The wave coupling can be further weakened by the random polarization of such beams. Numerical simulations demonstrate that the intensity threshold of stimulated Raman scattering in homogeneous plasmas can be doubled by using a sunlight-like laser beam with a relative bandwidth of ∼1% as compared with a monochromatic laser beam. Consequently, the hot-electron generation harmful to inertial confinement fusion can be effectively controlled by using sunlight-like laser drivers. Such drivers may be realized in the next generation of broadband lasers by combining two or more broadband beams with independent phase spectra or by applying polarization smoothing to a single broadband beam.