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Evaluation of fluences and surface characteristics in laser polishing SKD 11 tool steel
摘要： In this paper, a continuous-wave laser beam from a multimode fiber laser was applied to study the polishing effect. Three kinds of surface morphologies were acquired by fast-speed (FS) & lower-speed (LS) wire electrical discharge machining (EDM), milling processing methods on SKD11 tool steel. Then influence of laser fluence on the polished surface characteristics was analyzed. The results showed that surface roughness parameters (Ra, Rz, Rt, and Sa) can be significantly affected by this effect. With laser fluence increasing, the polished surface underwent a comprehensive topographical evolution from superficial surface melting to surface over-melting. The improvements by FS-EDM, LS-EDM, and milling in roughness were 86.83%, 90.70% and 86.07%, respectively. The corresponding laser fluences were 14.26 J/mm2, 12.73 J/mm2 and 13.55 J/mm2, indicating that LS-EDM tool steel surface has the best polishing effect. The comparative statistical results of the bearing area curve, bidirectional reflectance distribution function, and power spectral density from the LS-EDM surfaces showed the best polishing results. In addition, all the pre-prepared surfaces could be polished to Ra < 0.5 μm using high polishing velocities. These findings also signified that laser beam with top-hat distribution has a great potential for high-efficiency polishing of tool steel surfaces.
关键词： Power spectral density,Surface morphology,Bearing area curve,Fluence,Laser polishing,Tool steel
更新于2025-11-28 14:24:20
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Translating chemometric analysis into physiological insights from in vivo confocal Raman spectroscopy of the human stratum corneum
摘要： The superficial layer of the skin, the stratum corneum (SC), consists of corneocytes surrounded by lipid regions and acts as a protective barrier for the body against water loss, toxic agents and microorganisms. As most substances permeate the stratum corneum through the lipid regions, lipid organization is considered crucial for the skin barrier function. Here, we investigate the potential of in vivo confocal Raman spectroscopy to describe the composition and organization of the SC. Confocal Raman spectroscopy is finding increasing use in the characterization of skin in biomedical, pharmaceutical and cosmetic applications. In this work, we analyze the spectra using chemometric methods and obtain principal components that correspond to the primary skin constituents: protein (keratin), natural moisturizing factor (NMF), water and lipid contributions in both ordered (orthorhombic) and disordered structural organization. By identifying these important components of the SC, these results highlight the utility of this in vivo, non-invasive, and depth resolved tool at the forefront of skin research.
关键词： Skin barrier,Natural moisturizing factor,Multivariate curve resolution,Keratin,Lipid organization
更新于2025-11-14 15:16:37
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Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications
摘要： With reference of our previous report (Appl. Surf. Sci. 2018, ASAP), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (4000C – 4500C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using x-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.
关键词： XPS Spectroscopy,Layer-by-layer MoS2:GO composite thin films,I-V curve
更新于2025-10-22 19:40:53
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Photochemical multivariate curve resolution models for the investigation of photochromic systems under continuous irradiation
摘要： We propose a multivariate curve resolution approach for the investigation of photochromic systems using UV-Visible spectroscopy. The incorporation of photochemical hard-models as constraints in multivariate curve resolution alternating least squares (MCR-ALS) allows extracting reaction quantum yields in situations where a complete knowledge of the system is not available. We apply this approach to the study of the photochromism of CMTE (cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene) under continuous monochromatic irradiation. The mechanism, involving 3 species and 2 reversible reactions, is written and translated into a kinetic constraint that can be applied to the concentration profiles within ALS. First, ambiguity of the solution obtained for photochemical model(s) is calculated and discussed for single set analysis. Multiset analysis is then proposed combining data obtained under different irradiation wavelengths to provide more reliable results. Finally, the photochemical reactivity of CMTE is widely unraveled, and some description of the mechanism observed under irradiation at 365 nm is given.
关键词： Multivariate curve resolution,Quantum yield,Hard-soft modelling,Parameter ambiguity,Photochemical reaction
更新于2025-09-23 15:23:52
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Electrical Properties of Porous Silicon for N2 Gas Sensor
摘要： The application of porous silicon (PSi) for gas sensing devices has gained a considerable attention in the last decade. This work considers the electrical features of PSi layers prepared by electrochemical etching. We find that in order to get a better understanding of the absorption properties of PSi surface, it is necessary to know how the PSi morphology depends on the etching parameters. The physical structure of PSi, i.e., porosity, and pore size distribution can be controlled by changing the Hydrofluoric Acid concentration, current density, anodizing length and etching time in anodizing procedure. We describe our test system for gas sensors and investigate on the electrical behavior of PSi layers (p-type) in N2 gas for various fabrication conditions. The results show that the current density increases significantly as N2 gas is adsorbed. The measurements of the I-V characteristics were carried out at atmospheric pressure, room temperature, and with N2 gas as well.
关键词： Current-voltage curve,N2 gas,Porous silicon,Gas sensor
更新于2025-09-23 15:23:52
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A compact leaky-wave antenna using a planar spoof surface plasmon polariton structure
摘要： This article presents and validates a leaky-wave antenna by using the spoof surface plasmon polariton (SSPP) technique. By properly designing the proposed SSPP unit, the SSPP wave can be switched between the confinement and radiation modes. A large radiation efficiency can be achieved by properly designing the modulation depth, which ensures that a compact SSPP leaky-wave array can be realized by using a small number of SSPP radiation units. To verify the design, a prototype which consists of a SSPP feeding network and a 4 by 4 SSPP radiation units has been fabricated by using a low cost FR-4 substrate. A good agreement between simulated and measured results has been obtained. The proposed array antenna shows the promising capability of the SSPP technique for leaky-wave antenna applications.
关键词： dispersion curve,the spoof surface plasmon polariton (SSPP),SSPP antenna array,SSPP power divider
更新于2025-09-23 15:23:52
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High-precision FBG demodulation using amplitude ratio curve with sharp peak
摘要： For the fiber Bragg grating (FBG) sensor based on the reflection peak position searching demodulation algorithms, a key problem is that the demodulation precision of measurement signal is seriously limited by the full width half maximum (FWHM) of the FBG reflection spectrum. In this paper, in order to overcome this problem and enhance the measurement precision, we proposed a high-precision demodulation method based on amplitude ratio curve to instead of the FBG reflection spectrum, which can increase the sensing precision significantly. In this method, the Bragg wavelength of FBG is modulated periodically with a sinusoidal function to obtain a series of reflection spectra. Then at each wavelength the amplitude ratio between second harmonic frequency component and fundamental frequency component is calculated to create the amplitude ratio curve. Here, we present a comprehensive theoretical analysis and experimental demonstration to verify the advantages of this method. Comparing with the demodulation method based on the FBG reflection spectrum, the average maximum measure error (MME) of Bragg wavelength is reduced from ± 1.54 pm to ± 0.15 pm, which improved by 10.3 times. In addition, the influence of the modulation amplitude and sampling frequency on demodulation accuracy are also studied in this paper.
关键词： Amplitude ratio curve,High precision temperature measurement,Fiber Bragg grating
更新于2025-09-23 15:23:52
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FPGA-Based Implementation of an Artificial Neural Network for Measurement Acceleration in BOTDA Sensors
摘要： In recent years, using distributed fiber-optic sensors based on Brillouin scattering, for monitoring pipelines, tunnels, and other constructional structures have gained huge popularity. However, these sensors have a low signal-to-noise ratio (SNR), which usually increases their measurement error. To alleviate this issue, ensemble averaging is used which improves the SNR but in return increases the measurement time. Reducing the noise by averaging requires hundreds or thousands of scans of the optical fiber; hence averaging is usually responsible for a large percent of the entire system latency. In this paper, we propose a novel method based on artificial neural network for SNR enhancement and measurement acceleration in distributed fiber-optic sensors based on the Brillouin scattering. Our method takes the noisy Brillouin spectrums and improves their SNR by 20 dB, which reduces the measurement time significantly. It also improves the accuracy of the Brillouin frequency shift estimation process and its latency by more than 50% in comparison with the state-of-the-art software and hardware solutions.
关键词： Artificial neural network (ANN),digital signal processing,optical fibers,curve fitting,field-programmable gate arrays (FPGAs)
更新于2025-09-23 15:23:52
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Effect of laser forming on mechanical properties of multiple-phase steels by using a thermal–microstructure–mechanical model
摘要： Based on a forming temperature-controlled mixed strain-hardening law, a temperature-controlled thermal–microstructure–mechanical model was developed to predict the deformation in ferrite–martensite dual-phase steel before and after complex laser forming. Phase transformation in dual phase steel was predicted by coupling a kinetic transformation model with the developed model during laser forming. The corresponding algorithm of the constitutive model was used in three-dimensional finite element method to simulate the material deformation and mechanical properties during the laser forming. The simulated results agree well with the experimental results. Laser forming influences the mechanical properties of the material significantly, leads to bending deformation of the scanned sample and induces a ferrite-to-martensite transformation. The influence of scanning line number on the tensile strength and bending deformation of the scanned specimen was investigated. The tensile strength and bending angle are related positively to the number of scanning lines on the sample.
关键词： Stress-strain curve,Phase transformation,Thermal–microstructure–mechanical model,Sheet metal,Laser forming
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Shenzhen, China (2018.7.13-2018.7.15)] 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Real-time Path Planning Based on IRRT Algorithm in 3D Environment
摘要： This paper presents a real-time path planning method for unmanned aerial vehicles(UAVs) navigation in 3D environment. In this study, 3D point clouds are processed into octomap, which is the octree-based 3D map representation of environment and is a probabilistic representation of occupancy including free and unknown areas. Rapidly-exploring random tree is improved by introducing the random probability and storing relatively optimal path with a certain number of iterations, called iteration rapidly-exploring random tree, to find a collision-free path in the free areas. Down-sampling and curve fitting by Bezier curve are performed to smooth path that satisfy the constraints of flight trajectory of UAVs. Experimental results verify the proposed algorithm and prove that it is valid.
关键词： octree,real-time,planning,iteration rapidly-exploring random tree(IRRT),Bezier curve,path
更新于2025-09-23 15:22:29