Transmission error (TE) has emerged as a reliable indicator for fault diagnosis. However, in harmonic reducers, the non-stationary nature of measured TE signals results in the coupling of fault information with variou...
Transmission error (TE) has emerged as a reliable indicator for fault diagnosis. However, in harmonic reducers, the non-stationary nature of measured TE signals results in the coupling of fault information with various interference components, including manufacturing and assembly errors, thereby complicating fault feature identification. To address this issue, this paper first establishes a TE model that accounts for multiple error sources. Simulations of TE under fault conditions reveal that high-frequency components exhibit periodic peaks with distinct fault characteristics, rendering them effective as fault-sensitive features. Building upon the prior analysis, a comprehensive TE-based fault diagnosis framework for harmonic reducers is proposed, termed VMD-DRGAF-Swin Transformer. Initially, the VMD-DRGAF method is proposed for TE signal decomposition and fault feature fusion. This method extracts multi-modal fault-sensitive components and converts them into RGB images. Subsequently, the fused multi-modal images are input into a Swin Transformer-based diagnostic model for fault identification. Finally, an experimental TE signal dataset is collected to validate the diagnostic performance of the proposed method. The results demonstrate that the proposed method achieves higher diagnostic accuracy under various operating conditions, exhibiting strong generalization capabilities. Furthermore, ablation experiments confirm that the VMD-DRGAF method significantly enhances the fault recognition ability and robustness of the diagnostic model, outperforming traditional methods.
We present a high-sensitivity and high-resolution birefringence coefficient determination system for nm-level membrane films based on weak measurement, addressing the sensitivity-resolution trade-off. A tunable bandwi...
An ideal holographic 3D display should have the characteristics of large viewing angle,full color,and low speckle ***,the viewing angle of the holographic 3D display is usually limited by existing strategies,which vas...
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An ideal holographic 3D display should have the characteristics of large viewing angle,full color,and low speckle ***,the viewing angle of the holographic 3D display is usually limited by existing strategies,which vastly hinders its extensive *** this paper,a large viewing angle holographic 3D display system based on maximum diffraction modulation is *** core of the proposed system comprises the spatial light modulators(SLMs)and liquid crystal *** also present a new feasible scheme for the realization of large viewing angle holographic 3D *** is achieved by considering the maximum diffraction angle of SLM as the limited diffraction modulation range of each image *** doing so,we could not only give access to the maximum hologram size of the object,but also tune the reconstructed image of secondary diffraction by using a self-engineered liquid crystal *** importantly,the proposed maximum diffraction modulation scheme enables the viewing angle of the proposed system to be enlarged to 73.4°.The proposed system has huge application potential in the fields such as education,culture,and entertainment.
Dynamic states in mutual-coupled mid-infrared quantum cascade lasers(QCLs) were numerically investigated in the parameter space of injection strength and detuning frequency based on the Lang-Kobayashi equations model....
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Dynamic states in mutual-coupled mid-infrared quantum cascade lasers(QCLs) were numerically investigated in the parameter space of injection strength and detuning frequency based on the Lang-Kobayashi equations model. Three types of period-one states were found, with different periods of injection time delay τ_(inj), 2τ_(inj), and reciprocal of the detuning frequency. Besides, square-wave, quasi-period, pulse-burst and chaotic oscillations were also observed. It is concluded that external-cavity periodic dynamics and optical modes beating are the mainly periodic dynamics. The interaction of the two periodic dynamics and the high-frequency dynamics stimulated by strong injection induces the dynamic states *** work helps to understand the dynamic behaviors in QCLs and shows a new way to mid-infrared wide-band chaotic laser.
Recently, researches on the reliability analysis of phased mission systems (PMSs) are very popular. And most of the existing research on PMSs assumed that all the components are statistically independent on each other...
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Recently, researches on the reliability analysis of phased mission systems (PMSs) are very popular. And most of the existing research on PMSs assumed that all the components are statistically independent on each other, which is not meet the engineering reality. The system structure changes from phase to phase in the PMSs, so the dependency among components may also change in different phases. Meanwhile, the well-known phase dependency is also existing in the system reliability modeling. To model the varying dependency among components and phase dependency at the same time, a copula-based method is proposed for the reliability analysis of PMS with correlated components. Firstly, the system reliability of multi-state PMS with dependent components is evaluated by different copula functions. Then, multiple indicators are used to select the optimal copula functions for different phases. And an engineering case is illustrated to show the proposed copula-based method.
By introducing an optic-null medium into the finite embedded transformation,a reflectionless spatial beam bender is designed,which can steer the output beam by a fixed pre-designed angleβfor an arbitrary incident ***...
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By introducing an optic-null medium into the finite embedded transformation,a reflectionless spatial beam bender is designed,which can steer the output beam by a fixed pre-designed angleβfor an arbitrary incident *** bending angleβof the beam bender is determined by the geometrical angle of the device,which can be changed by simply choosing different geometrical *** various bending angles,the designed spatial beam bender can be realized by the same materials(i.e.,an optic-null medium),which is a homogenous anisotropic *** simulations verify the reflectionless bending effect and rotated imaging ability of the proposed beam bender.A reduction model of the optic-null medium is studied,which can also be used for a reflectionless spatial beam bender with a pre-designed bending angle.
In this work,a method to acquire freestanding GaN by using low temperature(LT)-GaN layer was put *** obtain porous structure and increase the crystallinity,LT-GaN layers were annealed at high *** morphology of LTGaN l...
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In this work,a method to acquire freestanding GaN by using low temperature(LT)-GaN layer was put *** obtain porous structure and increase the crystallinity,LT-GaN layers were annealed at high *** morphology of LTGaN layers with different thickness and annealing temperature before and after annealing was *** of GaN films using different LT-GaN layers was made to acquire optimal LT-GaN *** to HRXRD and Raman results,GaN grown on 800 nm LT-GaN layer which was annealed at 1090℃ has good crystal quality and small *** GaN film was successfully separated from the substrate after cooling *** self-separation mechanism of this method was ***-sectional EBSD mapping measurements were carried out to investigate the effect of LT-buffer layer on improvement of crystal quality and stress *** optical property of the obtained freestanding GaN film was also determined by PL measurement.
In order to test the fault of belt longitudinal tear efficiently, an infrared image detection method using support vector machine (SVM) is proposed. The infrared images of belt are collected to avoid the adverse effec...
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In this paper, the performance of wavelet transform on the detection and location of pipeline leak are explored. The effects of three wavelets on different thresholds and different decomposition layers are studied. Fi...
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NIST(National Institute of Standards and Technology) statistical test recognized as the most authoritative is widely used in verifying the randomness of binary sequences. The Non-overlapping Template Matching Test as ...
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NIST(National Institute of Standards and Technology) statistical test recognized as the most authoritative is widely used in verifying the randomness of binary sequences. The Non-overlapping Template Matching Test as the 7 th test of the NIST Test Suit is remarkably time consuming and the slow performance is one of the major hurdles in the testing process. In this paper, we present an efficient bit-parallel matching algorithm and segmented scan-based strategy for execution on Graphics Processing Unit(GPU) using NVIDIA Compute Unified Device Architecture(CUDA). Experimental results show the significant performance improvement of the parallelized Non-overlapping Template Matching Test, the running speed is 483 times faster than the original NIST implementation without attenuating the test result accuracy.
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