- 标题
- 摘要
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- 实验方案
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Unidirectional transport and effective collection of underwater CO2 bubbles utilizing ultrafast-laser-ablated Janus foam
摘要： Manipulating gas bubbles in aqueous ambient is of great importance for applications in water treatment, gas collection and matter transport. Here, a kind of Janus foam is designed and fabricated by one-step ultrafast laser ablation of one side of cooper film, which is treated to be superhydrophobic. The Janus foam exhibits not only the capability of unidirectional transport of underwater bubbles, but also gas collection with favorable efficiency up to ~15 mL cm-2 min-1. The underlying physical mechanism is attributed to the cooperation of the buoyancy, adhesion and wetting gradient forces imposed on the bubbles. As a paradigm, the underwater chemical reaction between unidirectional CO2 gas flow and alkaline phenolphthalein solution is demonstrated via the Janus foam. This facile and low-cost fabrication approach for Janus foam will find broad potential applications for effective bubble transport, carbon capture and controllable chemical reactions in aqueous conditions.
关键词： Janus foam,Unidirectional bubble transport,Ultrafast laser,Wetting gradient force,Directional bubble collection
更新于2025-09-23 15:19:57
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Light-Gated Synthetic Protocells for Plasmon-Enhanced Chemiosmotic Gradient Generation and Phosphorylation
摘要： Here, we present the construction of a light-gated protocell model made of plasmonic colloidal capsules (CCs) assembled with lipoprotein bacteriorhodopsin for converting solar energy into electrochemical gradients and further driving synthesis of energy storage molecules. Not only did this synthetic protocell incorporate essential features of CCs, but it also assimilated such an important intrinsic property of noble metal colloidal particles as plasmonic resonance. Specially, the near-field coupling between adjacent metal nanoparticles gave rise to strongly localized electric fields and resulted in a broad absorption in the whole visible spectra, which in turn promoted to bacteriorhodopsin and accelerated the proton pumping kinetics. The cell-like potential of this design was further demonstrated by leveraging the outward pumped protons as 'chemical signals' for triggering ATP biosynthesis in a coexistent synthetic protocell population. Hereby, we lay the groundwork for engineering of colloidal supraparticle-based synthetic protocells with higher-order functionalities.
关键词： protocell,colloidal capsule,bacteriorhodopsin,plasmonic resonance,chemiosmotic gradient
更新于2025-09-19 17:15:36
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Effective and Efficient Photo -Based PM2.5 Concentration Estimation
摘要： Air pollution has become a worldwide concerned issue and automatical estimation of air quality can provide a positive guidance to both individual and industrial behaviors. Given that the traditional instrument-based method requires high economic, labor costs on instrument purchase and maintenance, this paper proposes an effective, efficient, and cheap photo-based method for the air quality estimation in the case of particulate matter (PM2.5). The success of the proposed method lies in extracting two categories of features (including the gradient similarity and distribution shape of pixel values in the saturation map) by observing the photo appearances captured under different PM2.5 concentrations. Specifically, the gradient similarity is extracted to measure the structural information loss with the consideration that PM2.5 attenuates the light rays emitted from the objects and accordingly distorts the structures of the formed photo. Meanwhile, the saturation map is fit by the Weibull distribution to quantify the color information loss. By combining two features, a primary PM2.5 concentration estimator is obtained. Next, a nonlinear function is adopted to map the primary one to the real PM2.5 concentration. Sufficient experiments on real data captured by professional PM2.5 instrument demonstrate the effectiveness and efficiency of the proposed method. Specifically, it is highly consistent with real sensor’s measures and requires low implementation time.
关键词： saturation map,Air quality estimation,PM2.5 concentration,photo-based,gradient similarity
更新于2025-09-19 17:15:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - ACCELERATING THE TRAINING PROCESS OF CONVOLUTIONAL NEURAL NETWORKS FOR CLASSIFICATION BY DROPPING TRAINING SAMPLES OUT
摘要： Stochastic gradient descent and other adaptive optimization methods such as RMSprop, and Adam have been proved effective for training deep neural networks [1,2]. Within each epoch of these methods, the whole training set is involved. In general, large training datasets have data redundancy. In this paper, we investigate an algorithm that reduce the training time of CNN by dropping certain samples out. Thus, it is called DropSample. This method can be viewed as a special type of truncated cross-entropy loss with a finite margin. We design experiments on several datasets to demonstrate the effects of acceleration. The results show that this method could decrease the training time of multilayer perceptrons (MLPs) and convolutional neural networks (CNNs) significantly. Despite reduced number of training samples, the accuracies of networks are similar, or even better.
关键词： gradient descent,sampling,DropSample,acceleration
更新于2025-09-19 17:15:36
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[Methods in Molecular Biology] Immunological Tolerance Volume 1899 (Methods and Protocols) || Improvement of Signal-to-Noise Ratio for MST Radar Using Weighted Semi-parametric Algorithm
摘要： The Indian mesosphere–stratosphere–troposphere (MST) radar is the prominent atmospheric radar that provides the atmospheric movements’ information. The radar data is analyzed to obtain the wind parameter that requires the power spectral estimation. At higher altitudes, the estimation of Doppler spectrum is found to be unsatisfactory using both parametric and nonparametric methods for spectral estimation. In this article, the hyperparameter-free, weighted sparse iterative covariance-based estimation (SPICE) method has been considered. Unlike existing SPICE method, a different hyperparameter–free, weighted SPICE method has been derived using a gradient approach with different step sizes. The two versions of SPICE algorithm, i.e., SPICEa and SPICEb, are applied to the practical MST radar data collected at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E). The obtained results are evaluated with the existing atmospheric data processor results which use the basic periodogram method. The proposed method shows the signi?cant enhancement in signal-to-noise ratio even at elevated heights.
关键词： Gradient approach,Doppler spectrum,MST radar,SPICE
更新于2025-09-19 17:15:36
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Additive Manufacturing of Three-dimensional Metal-glass Functionally Gradient Material Components by Laser Powder Bed Fusion with In situ Powder Mixing
摘要： Existing commercial three-dimensional (3D) printing systems based on powder bed fusion approach can normally only print a single material in each component. In this paper, functionally gradient materials (FGM) with composition variation from a copper alloy to a soda-lime glass were manufactured using a proprietary nozzle-based multi-material selective laser melting (MMSLM) system. An in situ powder mixing system was designed to mix both metal and glass powders at selective ratios and the mixed powders were dispensed with an ultrasonic vibration powder feeding system with multiple nozzles. From the cross section analysis of the gradient structures, glass proportion increased gradually from the metallic matrix composite (MMC), transition phase to ceramic matrix composite (CMC). The pure copper alloy joined the MMC part and the pure glass phase penetrated into the CMC part during laser processing, which anchored the glass phase, as the main mechanism of combining pure metal and pure glass by FGM in 3D printed parts. From results of indentation, tensile and shear tests on the gradient material samples, it showed that mechanical properties of the FGM gradually changed from ductility (metal side) to brittle (glass side). The weakest part of the FGM structure occurred at the interface between transition phase and the CMC, which was also the interface between the ductile and brittle phases.
关键词： copper-glass,Powder Bed Fusion,horizontal gradient structure,multi-material selective laser melting,functionally gradient materials
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Metamaterials, Anapoles and Flying Donuts
摘要： Heat-assisted magnetic recording (HAMR) allows for data writing in hard disks beyond 1 Tb/in2 areal density, by temporarily heating the area of a single bit to its Curie temperature. The metallic optical antenna or near-?eld transducer (NFT), used to apply the nanoscale heating to the media, may self-heat by several hundreds of degrees. With the NFT reaching such extreme temperatures, demonstrations of HAMR technology experience write-head lifetimes that are orders of magnitude less than that required for a commercial product. Hence, heating of the NFT is of upmost importance. In this paper, we ?rst derive fundamental limits on the temperature ratio NFT/Media to drive NFT design choices for low-temperature operation. Next, we employ inverse electromagnetic design software, which solves for unexpected geometries of the NFT and waveguide. We present computationally generated designs for the waveguide feeding the NFT that offer a 50% reduction in NFT self-heating (～220 °C) compared with typical industry designs.
关键词： HAMR,optimization,plasmonics,nanophotonics,near-?eld transducer (NFT),inverse problem,heat-assisted magnetic recording thermal,computational electromagnetics,hard disks,gradient methods,management,Adjoint method,optical antenna
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Telecom Laser Lock on Acetylene Line for Applications in Cold Atoms Experiments
摘要： The application of fractional calculus to signal processing and adaptive learning is an emerging area of research. A novel fractional adaptive learning approach that utilizes fractional calculus is presented in this paper. In particular, a fractional steepest descent approach is proposed. A fractional quadratic energy norm is studied, and the stability and convergence of our proposed method are analyzed in detail. The fractional steepest descent approach is implemented numerically and its stability is analyzed experimentally.
关键词： Fractional calculus,fractional extreme point,fractional gradient,fractional differential,steepest descent (FOSD) method,fractional energy norm
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Ultrafast Light Source at 1.8 ??m Based on Thulium-Doped Fibers for Three-Photon Microscopy
摘要： Optical tomographic imaging requires an accurate forward model as well as regularization to mitigate missing-data artifacts and to suppress noise. Nonlinear forward models can provide more accurate interpretation of the measured data than their linear counterparts, but they generally result in computationally prohibitive reconstruction algorithms. Although sparsity-driven regularizers significantly improve the quality of reconstructed image, they further increase the computational burden of imaging. In this paper, we present a novel iterative imaging method for optical tomography that combines a nonlinear forward model based on the beam propagation method (BPM) with an edge-preserving three-dimensional (3-D) total variation (TV) regularizer. The central element of our approach is a time-reversal scheme, which allows for an efficient computation of the derivative of the transmitted wave-field with respect to the distribution of the refractive index. This time-reversal scheme together with our stochastic proximal-gradient algorithm makes it possible to optimize under a nonlinear forward model in a computationally tractable way, thus enabling a high-quality imaging of the refractive index throughout the object. We demonstrate the effectiveness of our method through several experiments on simulated and experimentally measured data.
关键词： Optical phase tomography,beam propagation method,compressive sensing,total variation regularization,stochastic proximal-gradient,sparse reconstruction
更新于2025-09-19 17:13:59
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Spatial tailoring of the refractive index in infrared glass-ceramic films enabled by direct laser writing
摘要： The development of infrared gradient refractive index (GRIN) components relies on the ability to modify the refractive index and dispersion properties of suitable host materials with a high spatial selectivity and a sufficient magnitude of change. We present a novel multi-step approach to induce local refractive index changes in chalcogenide optical materials. Films with thicknesses between 1 and 40 μm fabricated from multi-component GeSe2-As2Se3-PbSe (GAP–Se) glass-ceramic materials were irradiated with continuous-wave and nanosecond-pulsed laser light, and post-processed with heat-treatments. A maximum local refractive index change of Δn = 0.088 across a broad spectral range in the infrared was realized. Spatial control of the refractive index variation was achieved through thermally-induced crystallization of a Pb-rich crystal phase. The magnitude of the index change scaled with the laser power and the exposure dose while the material maintained the required optical quality. The material performance validated in this study for thick films (20–40 μm films) reconfirms our ability to extend results from thin GAP-Se films towards novel optical designs.
关键词： Direct laser writing,Chalcogenide glass,Photo-thermal process,Gradient refractive index
更新于2025-09-19 17:13:59