Existing neurosurgical robots are prone to interfering with each other in a narrow operating space due to the overlapping of several arms, which poses a great safety risk during surgery. In this paper, a 7-DOF dual-ar...
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The sensing spatial resolution and signal-to-noise ratio(SNR)of Raman distributed optical fiber sensors are limited by the pulse width and weak Raman scattering ***,the sensing spatial resolution cannot exceed the ord...
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The sensing spatial resolution and signal-to-noise ratio(SNR)of Raman distributed optical fiber sensors are limited by the pulse width and weak Raman scattering ***,the sensing spatial resolution cannot exceed the order of meters at several kilometers sensing *** break through this physical bottleneck,a novel,to our knowledge,Raman scattering model based on paired-pulse sensing is *** fundamental origins of the observed limited spatial resolution of conventional schemes are analyzed,and a chaotic asymmetric paired-pulse correlation-enhanced scheme for Raman distributed fiber-optic sensing is proposed and experimentally *** proposed scheme uses a chaotic asymmetric paired-pulse as the sensing signal and extracts the light intensity information of each data point of the sensing fiber,which carries the random undulation characteristics of chaotic time series,based on the time-domain differential reconstruction *** scheme overcomes the pulse width limitation of spatial resolution via correlation and demodulation,enhances the correlation characteristics between the temperature-modulated Raman scattered light field and detection signal,and improves the ***,a sensing performance of 10 km,a spatial resolution of 30 cm,and an SNR of 6.67 dB are realized in the *** scheme provides a new research idea for a high-performance Raman distributed optical fiber sensing system.
We systematically investigate the four-wave mixing(FWM)spectrum in a dual-cavity hybrid optomechanical system,which is made up of one optical cavity with an ensemble of two-level atoms and another with a mechanical **...
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We systematically investigate the four-wave mixing(FWM)spectrum in a dual-cavity hybrid optomechanical system,which is made up of one optical cavity with an ensemble of two-level atoms and another with a mechanical *** this work,we propose that the hybrid dual-cavity optomechanical system can be employed as a highly sensitive mass sensor due to the fact that the FWM spectrum generated in this system has a narrow spectral width and the intensity of the FWM can be easily tuned by controlling the coupling strength(cavity-cavity,atom-cavity).More fascinatingly,the dual-cavity hybrid optomechanical system can also be used as an all-optical switch in view of the easy on/off control of FWM signals by adjusting the atom-pump detuning to be positive or *** proposed schemes have great potential applications in quantum information processing and highly sensitive detection.
To enhance the safety and longevity of large ships, employing high-pressure water jet technology for rust removal is crucial in this article, the qualitative relationship among the key parameters of high-pressure wate...
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In this study, double-physical-fields null medium, i.e., a subwavelength air channels surrounded by a carefully arranged metal plates, is utilized to design an electromagnetic-acoustic beam compressor capable of simul...
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ISBN:
(数字)9798350375909
ISBN:
(纸本)9798350375916
In this study, double-physical-fields null medium, i.e., a subwavelength air channels surrounded by a carefully arranged metal plates, is utilized to design an electromagnetic-acoustic beam compressor capable of simultaneously compressing electromagnetic waves and acoustic waves. Numerical simulation results verify its ability to simultaneously produce the expected compression ratios for both electromagnetic waves and acoustic waves. Moreover, the compression ratio precisely matches the geometric size ratio of the input and output planes of the compressor. This work may have potential applications in electromagnetic-acoustic coupling systems and electromagnetic-acoustic processing/detection.
Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In th...
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Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (Rt). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (Um) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h_(2) < 0, h_(2) is the height of expanded channel for E-MCHS) and when over plate was raised (h_(2) > 0).
In previous study, many single-function static/quasi-static magnetic devices, such as cloak and concentrator, have been designed base on transformation optics. However, few have explored devices capable of simultaneou...
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ISBN:
(数字)9798350375909
ISBN:
(纸本)9798350375916
In previous study, many single-function static/quasi-static magnetic devices, such as cloak and concentrator, have been designed base on transformation optics. However, few have explored devices capable of simultaneously generating two different functions on the static/quasi-static magnetic field. In this study, we propose a dual-function quasi-static magnetic device, which can create a concealed region and concentrated region for quasi-static magnetic field simultaneously. The dual-function quasi-static magnetic device is designed via twice extreme spatial stretching transformation and magnetic null medium, which can be realized by using arrays of superconductors and ferromagnetic materials in specific arrangement. The simulated results verify the performance of the proposed dual-function quasi-static magnetic device, which can simultaneously achieve cloaking and concentrating effect for the magnetic field from DC to 1000 Hz. The quasi-static magnetic field can be enhanced 9 times than the background magnetic field when the side lengths of the internal square pillar and external square pillar of the proposed structure are selected as a = 10 mm and b = 90 mm, respectively. Moreover, the concentrating ratio obtained from theoretical calculation fits well with the results obtained through numerical simulation. The dual-function quasi-static magnetic device designed in this study may have essential application in medical testing for special occasions.
The sensitivity to fault reflection is very important for larger dynamic range in fiber fault detection *** time delay signature(TDS)of chaotic laser formed by optical feedback can solve the sensitivity limitation of ...
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The sensitivity to fault reflection is very important for larger dynamic range in fiber fault detection *** time delay signature(TDS)of chaotic laser formed by optical feedback can solve the sensitivity limitation of photodetector in fiber fault *** TDS corresponds to the feedback position and the fault reflection can be detected by the laser *** sensitivity to feedback level of circular-side hexagonal resonator(CSHR)microcavity laser is numerically simulated and the feedback level boundaries of each output dynamic state are *** peak level of TDS is utilized to analyze the *** demonstration is presented in two aspects:the minimum feedback level when the TDS emerges and the variation degree of TDS level on feedback level *** results show that the CSHR microcavity laser can respond to the feedback level of 0.07%,corresponding to-63-dB feedback *** to conventional distributed feedback laser,the sensitivity improves almost 20 dB due to the shorter internal cavity length of CSHR microcavity ***,1%feedback level changing will induce 1.001 variation on TDS level,and this variation degree can be influenced by other critical internal parameters(active region side length,damping rate,and linewidth enhancement factor).
The control of ultrafast optical field is of great interest in developing ultrafast optics as well as the investigation on vari-ous light-matter interactions with ultrashort ***,conventional spatial encoding approache...
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The control of ultrafast optical field is of great interest in developing ultrafast optics as well as the investigation on vari-ous light-matter interactions with ultrashort ***,conventional spatial encoding approaches have only lim-ited steerable targets usually neglecting the temporal effect,thus hindering their broad *** we present a new concept for realizing ultrafast modulation of multi-target focal fields based on the facile combination of time-depend-ent vectorial diffraction theory with fast Fourier *** is achieved by focusing femtosecond pulsed light carrying vectorial-vortex by a single objective lens under tight focusing *** is uncovered that the ultrafast temporal de-gree of freedom within a configurable temporal duration(~400 fs)plays a pivotal role in determining the rich and exotic features of the focused optical field at one time,namely,bright-dark alternation,periodic rotation,and longitudinal/trans-verse polarization *** underlying control mechanisms have been *** being of academic in-terest in diverse ultrafast spectral regimes,these peculiar behaviors of the space-time evolutionary beams may underpin prolific ultrafast-related applications such as multifunctional integrated optical chip,high-efficiency laser trapping,micro-structure rotation,super-resolution optical microscopy,precise optical measurement,and liveness tracking.
Dermal substitutes have provided a template for the regeneration and reconstruction of the ***,the healed skin tissue often exhibits abnormal morphology and functionality,including scarring and *** this study,a compos...
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Dermal substitutes have provided a template for the regeneration and reconstruction of the ***,the healed skin tissue often exhibits abnormal morphology and functionality,including scarring and *** this study,a composite bioink composed of methacrylated gelatin(GelMA)and chitosan oligosaccharide(COS)was proposed for printing a dermal scaffold using digital light processing(DLP)*** GelMA/COS bioink exhibited suitable porosity,swelling,degradation rate,and mechanical *** inclusion of COS demonstrated antibacterial effects against both Gram positive and Gram-negative bacteria,while simultaneously fostering the proliferation of human dermal fibroblasts(HDFs).Additionally,the application of COS could effectively reduce the expression levels of fibrosis-related genes,such as collagen I,collagen III,and fibronectin *** three-dimensionally printed cell-laden dermal scaffold exhibited excellent shape fidelity and high cellular viability,facilitating the extension of HDFs along the scaffold and the simultaneous secretion of extracellular matrix ***,the HDF-laden dermal scaffold transplanted into full-thickness skin defect sites in nude mice was shown to accelerate wound closure,reduce inflammation,and improve wound ***,the DLP-printed dermal scaffold provides an appealing approach for effectively treating full-thickness skin defects in clinical settings.
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