Subjects -> PHYSICS (Total: 857 journals)
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    - NUCLEAR PHYSICS (53 journals)
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    - PHYSICS (625 journals)
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    - THERMODYNAMICS (30 journals)

PHYSICS (625 journals)            First | 1 2 3 4 | Last

Showing 201 - 400 of 741 Journals sorted alphabetically
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 36)
International Journal of Biological, Physical and Chemical Studies     Open Access  
International Journal of Computational Materials Science and Surface Engineering     Hybrid Journal   (Followers: 7)
International Journal of Damage Mechanics     Hybrid Journal   (Followers: 5)
International Journal of Engineering and Applied Physics     Open Access  
International Journal of Fatigue     Hybrid Journal   (Followers: 41)
International Journal of Fracture     Hybrid Journal   (Followers: 14)
International Journal of Geometric Methods in Modern Physics     Hybrid Journal   (Followers: 2)
International Journal of Geophysics     Open Access   (Followers: 5)
International Journal of Heat and Fluid Flow     Hybrid Journal   (Followers: 41)
International Journal of Low Radiation     Hybrid Journal  
International Journal of Low-Carbon Technologies     Open Access   (Followers: 1)
International Journal of Mass Spectrometry     Hybrid Journal   (Followers: 17)
International Journal of Material Forming     Hybrid Journal   (Followers: 1)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 2)
International Journal of Mechanical Sciences     Hybrid Journal   (Followers: 14)
International Journal of Mechanics and Materials in Design     Hybrid Journal   (Followers: 7)
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology     Open Access   (Followers: 11)
International Journal of Microstructure and Materials Properties     Hybrid Journal   (Followers: 7)
International Journal of Microwave Science and Technology     Open Access   (Followers: 12)
International Journal of Modeling, Simulation, and Scientific Computing     Hybrid Journal   (Followers: 3)
International Journal of Modern Physics A     Hybrid Journal   (Followers: 15)
International Journal of Modern Physics B     Hybrid Journal   (Followers: 12)
International Journal of Modern Physics C     Hybrid Journal   (Followers: 14)
International Journal of Modern Physics D     Hybrid Journal   (Followers: 13)
International Journal of Modern Physics E     Hybrid Journal   (Followers: 13)
International Journal of Multiphysics     Open Access  
International Journal of Nanomanufacturing     Hybrid Journal  
International Journal of Nanoscience     Hybrid Journal  
International Journal of Nanotechnology     Hybrid Journal   (Followers: 9)
International Journal of Non-Linear Mechanics     Hybrid Journal   (Followers: 8)
International Journal of Nonlinear Dynamics and Control     Hybrid Journal   (Followers: 6)
International Journal of Physics     Open Access   (Followers: 10)
International Journal of PIXE     Hybrid Journal  
International Journal of Plasticity     Hybrid Journal   (Followers: 7)
International Journal of Quantum Information     Hybrid Journal   (Followers: 6)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal  
International Journal of Solids and Structures     Hybrid Journal   (Followers: 14)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 6)
International Journal of Theoretical and Applied Multiscale Mechanics     Hybrid Journal   (Followers: 3)
International Journal of Theoretical and Mathematical Physics     Open Access   (Followers: 13)
International Journal of Theoretical Physics     Hybrid Journal   (Followers: 17)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 18)
International Journal on Smart Sensing and Intelligent Systems     Open Access  
International Letters of Chemistry, Physics and Astronomy     Open Access   (Followers: 8)
International Materials Reviews     Hybrid Journal   (Followers: 15)
Iranian Journal of Medical Physics     Open Access  
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 4)
Izvestiya, Atmospheric and Oceanic Physics     Full-text available via subscription   (Followers: 1)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 2)
Jambura Physics Journal     Open Access  
JETP Letters     Hybrid Journal   (Followers: 3)
Journal of Adhesion Science and Technology     Hybrid Journal   (Followers: 10)
Journal of Advanced Physics     Full-text available via subscription   (Followers: 13)
Journal of Advances in Physics     Open Access   (Followers: 13)
Journal of Applied Mathematics and Physics     Open Access   (Followers: 9)
Journal of Applied Mechanics and Technical Physics     Hybrid Journal   (Followers: 7)
Journal of Applied Physics     Hybrid Journal   (Followers: 69)
Journal of Applied Spectroscopy     Hybrid Journal   (Followers: 9)
Journal of Astrophysics     Open Access   (Followers: 33)
Journal of Astrophysics and Astronomy     Open Access   (Followers: 58)
Journal of Building Physics     Hybrid Journal   (Followers: 1)
Journal of Chromatographic Science     Hybrid Journal   (Followers: 15)
Journal of Complex Networks     Hybrid Journal   (Followers: 1)
Journal of Composite Materials     Hybrid Journal   (Followers: 245)
Journal of Computational and Theoretical Transport     Hybrid Journal   (Followers: 2)
Journal of Computational Methods in Physics     Open Access   (Followers: 8)
Journal of Computational Physics     Hybrid Journal   (Followers: 59)
Journal of Computational Physics : X     Open Access   (Followers: 1)
Journal of Contemporary Physics (Armenian Academy of Sciences)     Hybrid Journal   (Followers: 9)
Journal of Dynamic Systems, Measurement, and Control     Full-text available via subscription   (Followers: 14)
Journal of Elasticity     Hybrid Journal   (Followers: 7)
Journal of Electron Spectroscopy and Related Phenomena     Hybrid Journal   (Followers: 3)
Journal of Electronic Materials     Hybrid Journal   (Followers: 3)
Journal of Electronics Cooling and Thermal Control     Open Access   (Followers: 9)
Journal of Engineering Materials and Technology     Full-text available via subscription   (Followers: 17)
Journal of Engineering Physics and Thermophysics     Hybrid Journal   (Followers: 2)
Journal of Experimental and Theoretical Physics     Hybrid Journal   (Followers: 4)
Journal of Experimental Physics     Open Access   (Followers: 3)
Journal of Fire Sciences     Hybrid Journal   (Followers: 6)
Journal of Geometry and Physics     Full-text available via subscription   (Followers: 2)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 137)
Journal of Gravity     Open Access   (Followers: 4)
Journal of High Energy Astrophysics     Full-text available via subscription   (Followers: 25)
Journal of High Energy Physics     Hybrid Journal   (Followers: 17)
Journal of High Energy Physics, Gravitation and Cosmology     Open Access   (Followers: 2)
Journal of Hydrogels     Full-text available via subscription  
Journal of Hyperspectral Remote Sensing     Open Access   (Followers: 23)
Journal of Imaging     Open Access   (Followers: 3)
Journal of Information Display     Open Access   (Followers: 1)
Journal of Intelligent Material Systems and Structures     Hybrid Journal   (Followers: 8)
Journal of Lightwave Technology     Hybrid Journal   (Followers: 14)
Journal of Low Frequency Noise, Vibration and Active Control     Open Access   (Followers: 8)
Journal of Luminescence     Hybrid Journal   (Followers: 2)
Journal of Materials Engineering and Performance     Hybrid Journal   (Followers: 22)
Journal of Materials Physics and Chemistry     Open Access   (Followers: 7)
Journal of Materials Science     Hybrid Journal   (Followers: 25)
Journal of Materials Science : Materials in Electronics     Hybrid Journal   (Followers: 2)
Journal of Materials Science : Materials in Medicine     Hybrid Journal   (Followers: 1)
Journal of Mathematical Fluid Mechanics     Hybrid Journal   (Followers: 10)
Journal of Mathematical Physics     Hybrid Journal   (Followers: 25)
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Medical Ultrasonics     Hybrid Journal   (Followers: 2)
Journal of Micro/Nanolithography MEMS and MOEMS     Hybrid Journal   (Followers: 24)
Journal of Molecular Spectroscopy     Hybrid Journal   (Followers: 6)
Journal of Motor Behavior     Hybrid Journal   (Followers: 8)
Journal of Multiscale Modeling     Hybrid Journal   (Followers: 1)
Journal of Nepal Physical Society     Open Access  
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Nonlinear Dynamics     Open Access   (Followers: 6)
Journal of Nonlinear Mathematical Physics     Hybrid Journal   (Followers: 2)
Journal of Nuclear Physics, Material Sciences, Radiation and Applications     Open Access   (Followers: 6)
Journal of Optics     Hybrid Journal   (Followers: 17)
Journal of Photonics for Energy     Hybrid Journal   (Followers: 2)
Journal of Physical and Chemical Reference Data     Hybrid Journal   (Followers: 4)
Journal of Physical Chemistry B     Hybrid Journal   (Followers: 48)
Journal of Physical Chemistry C     Hybrid Journal   (Followers: 36)
Journal of Physical Oceanography     Hybrid Journal   (Followers: 18, SJR: 2.461, CiteScore: 3)
Journal of Physical Organic Chemistry     Hybrid Journal   (Followers: 8)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 3)
Journal of Plasma Physics     Hybrid Journal   (Followers: 21)
Journal of Polymer Science Part B: Polymer Physics     Hybrid Journal   (Followers: 22)
Journal of Porous Materials     Hybrid Journal   (Followers: 4)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 1)
Journal of Quantitative Spectroscopy and Radiative Transfer     Hybrid Journal   (Followers: 3)
Journal of Reinforced Plastics and Composites     Hybrid Journal   (Followers: 30)
Journal of Rheology     Full-text available via subscription   (Followers: 7)
Journal of Sandwich Structures and Materials     Hybrid Journal   (Followers: 4)
Journal of Scientific Research     Open Access  
Journal of Sensors     Open Access   (Followers: 25)
Journal of Sol-Gel Science and Technology     Hybrid Journal  
Journal of Solid State Physics     Open Access   (Followers: 8)
Journal of Spectroscopy     Open Access   (Followers: 6)
Journal of Superconductivity and Novel Magnetism     Partially Free   (Followers: 1)
Journal of Synchrotron Radiation     Open Access   (Followers: 3)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 32)
Journal of the ICRU     Hybrid Journal  
Journal of the Korean Physical Society     Partially Free  
Journal of the Physical Society of Japan     Hybrid Journal   (Followers: 2)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 9)
Journal of Tissue Engineering     Open Access   (Followers: 6)
Journal of Ultrasound in Medicine     Full-text available via subscription   (Followers: 11)
Journal of Vibration and Control     Hybrid Journal   (Followers: 42)
Journal of Visualization     Hybrid Journal   (Followers: 3)
Journal of Zhejiang University : Sceince A     Hybrid Journal  
JPSE (Journal of Physical Science and Engineering)     Open Access  
Jurnal Fisika     Open Access  
Jurnal Ilmiah Pendidikan Fisika Al-Biruni     Open Access  
Jurnal NEUTRINO     Open Access  
Jurnal Online of Physics     Open Access  
Jurnal Pendidikan Fisika Indonesia (Indonesian Journal of Physics Education)     Open Access  
Jurnal Penelitian Fisika dan Aplikasinya     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Karbala International Journal of Modern Science     Open Access  
Kasuari : Physics Education Journal     Open Access  
La Rivista del Nuovo Cimento     Hybrid Journal  
Lasers in Surgery and Medicine     Hybrid Journal   (Followers: 1)
Latvian Journal of Physics and Technical Sciences     Open Access  
Letters in High Energy Physics     Open Access  
Letters in Mathematical Physics     Hybrid Journal   (Followers: 4)
Light : Science & Applications     Open Access   (Followers: 3)
Living Reviews in Computational Astrophysics     Open Access   (Followers: 3)
Living Reviews in Relativity     Open Access  
Living Reviews in Solar Physics     Open Access   (Followers: 1)
Lubrication Science     Hybrid Journal   (Followers: 2)
Macalester Journal of Physics and Astronomy     Open Access   (Followers: 5)
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 2)
Magnetic Resonance     Open Access  
Magnetic Resonance Letters     Open Access  
Magnetic Resonance Materials in Physics, Biology and Medicine     Hybrid Journal   (Followers: 3)
MAPAN     Hybrid Journal  
Mass Spectrometry Reviews     Hybrid Journal   (Followers: 31)
Matéria (Rio de Janeiro)     Open Access  
Materials and Design     Open Access   (Followers: 47)
Materials at High Temperatures     Full-text available via subscription   (Followers: 3)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 15)
Materials Research Bulletin     Hybrid Journal   (Followers: 25)
Materials Research Innovations     Hybrid Journal   (Followers: 1)
Materials Science     Hybrid Journal   (Followers: 7)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 44)
Materials Science and Engineering: B     Hybrid Journal   (Followers: 22)
Materials Science and Engineering: R: Reports     Hybrid Journal   (Followers: 15)
Materials Science and Technology     Hybrid Journal   (Followers: 40)
Materials Today Physics     Hybrid Journal   (Followers: 1)
Matériaux & Techniques     Full-text available via subscription   (Followers: 2)
Mathematical Physics, Analysis and Geometry     Hybrid Journal   (Followers: 3)
Mathematics and Mechanics of Solids     Hybrid Journal   (Followers: 3)
Matter and Radiation at Extremes     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechanics of Advanced Materials and Structures     Hybrid Journal   (Followers: 6)
Mechanics of Materials     Hybrid Journal   (Followers: 25)
Mechanics of Time-Dependent Materials     Hybrid Journal   (Followers: 2)
Mechanics Research Communications     Hybrid Journal   (Followers: 4)
Medical Physics     Hybrid Journal   (Followers: 17)
Micro and Nano Systems Letters     Open Access   (Followers: 6)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 11)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 9)
Modern Instrumentation     Open Access   (Followers: 57)
Modern Physics Letters A     Hybrid Journal   (Followers: 14)

  First | 1 2 3 4 | Last

Similar Journals
Journal Cover
Journal of Spectroscopy
Journal Prestige (SJR): 0.264
Citation Impact (citeScore): 1
Number of Followers: 6  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2314-4920 - ISSN (Online) 2314-4939
Published by Hindawi Homepage  [339 journals]
  • Detecting, Monitoring, and Analyzing the Surface Subsidence in the Yellow
           River Delta (China) Combined with CenterNet Network and SBAS-InSAR

    • Abstract: Long-term industrial activities tend to cause surface subsidence and damage to ground facilities and local ecological environment. Monitoring and analyzing surface subsidence is of great significance to prevent potential disasters. The surface type of the Yellow River Delta in China is complex and there are many industrial activities, so it is necessary to monitor the surface subsidence in this area. Small Baseline Subset InSAR (SBAS-InSAR) can monitor the surface subsidence with millimeter-level accuracy, but it takes a long time to process wide images (Sentinel-1) and is seriously affected by atmospheric errors. To avoid these limitations, we constructed a method combining the CenterNet network and SBAS-InSAR (CNSBAS-InSAR). Firstly, the CenterNet network is used to automatically detect the subsidence areas from the wide differential interferogram formed by two SAR satellite images and determine the location of the subsidence area. Then, the SBAS-InSAR monitoring is performed on the detected multiple subsidence areas. Finally, the small-scale subsidence results are obtained. In this study, based on 24 Sentinel-1A satellite images acquired from 10 January 2018 to 24 December 2018, nine subsidence areas in Yellow River Delta were detected. Three of them had long-term surface subsidence. They were located in Zhanhua District, Xianhe Town, and Hongguang Village, respectively. This paper focuses on analyzing these three areas. The maximum subsidence rate of Zhanhua District, Xianhe Town, and Hongguang Village were −135.21 mm/a, −330.91 mm/a, and −209.68 mm/a, respectively. In addition, the analysis showed that precipitation in the Zhanhua District could effectively slow down the subsidence rate of the area. The subsidence of Xianhe Town threatened the safety of the Shugang Expressway. The subsidence of Hongguang Village caused the safety risks of buildings. The results of this study prove that CNSBAS-InSAR method is reliable for monitoring subsidence areas and it can provide a reference for local construction and protection of Yellow River Delta.
      PubDate: Tue, 24 May 2022 08:35:03 +000
       
  • Laser-Induced Breakdown Spectroscopy (LIBS) for Trace Element Detection: A
           Review

    • Abstract: Laser-induced breakdown spectroscopy (LIBS) has emerged as a promising technique for both quantitative and qualitative analysis of elements in a wide variety of samples. However, conventional LIBS suffers from a high limit of detection (LoD) compared with other analytical techniques. This review briefly discusses several methods that demonstrate the applicability and prospects for trace element detection while lowering the LoD when coupled with LIBS. This review compares the enhancement mechanisms, advantages, and limitations of these techniques. Finally, the recent development and application of LIBS coupled techniques for trace element detection are also discussed for various samples such as metal alloys, biomaterials, rare earth elements, explosives, drinking water, and water bodies.
      PubDate: Sat, 21 May 2022 07:20:02 +000
       
  • Mathematically Processed UV Spectroscopic Method for Quantification of
           Chlorthalidone and Azelnidipine in Bulk and Formulation: Evaluation of
           Greenness and Whiteness

    • Abstract: A simple, eco-friendly four analytical methods were established by improving the selectivity through the application of mathematical processing of UV absorption spectra for concurrent quantification of chlorthalidone (CTL) and azelnidipine (AZE). The UV absorption spectra were recorded using environment-friendly ethanol (10% v/v) and were mathematically processed using simple software provided with a UV spectrophotometer. The analytes’ peak amplitude was determined using zero-crossing point first derivative spectra and ratio first derivative spectra of CTL and AZE, which were measured at 238.5 nm and 239.5 nm for CTL and 272.1 nm and 342.1 nm for AZE, respectively. The peak amplitude difference was determined from the ratio spectra of CTL and AZE by measuring the peak amplitudes at 211.8 and 267.2 nm for CTL and 328.4 and 286.1 nm for AZE. Further, ratio spectra of CTL and AZE were converted into zero-order spectra by subtracting the constant followed by multiplication with divisor spectra, and the peak amplitudes were measured at 226.9 nm and 257.3 nm for CTL and AZE zero-order spectra, respectively. Further, validation results of all the four methods confirmed the accuracy and precision of the methods by displaying good recovery (98.37–100.34%) and percentage relative standard deviation (0.397–1.758%), respectively. Good linearity was observed in the range of 1–15 μg/mL for both analytes with less than a 1 μg/mL limit of quantification. Further, the greenness and whiteness of the methods were evaluated by recently proposed AGREEness, complexGAPI, and white analytical chemistry techniques. The proposed UV spectroscopic methods were environmentally friendly, safe, economic, and effective, hence, could be used for regular quality control study of a formulation containing CTL and AZE.
      PubDate: Fri, 20 May 2022 09:50:02 +000
       
  • A Progressive Combined Variable Selection Method for Near-Infrared
           Spectral Analysis Based on Three-Step Hybrid Strategy

    • Abstract: A specific variable selection method was proposed based on a three-step hybrid strategy for near-infrared spectral analysis. By analyzing functions of each step and characteristics of various variable selection methods, synergy interval partial least squares, iterative variable subset optimization, and bootstrapping soft shrinkage were chosen for three steps. To test the effect of the three-step hybrid method, it was applied to corn and soil spectral data and compared to other common methods. Results for oil content in corn data showed that the three-step hybrid variable selection method selected 1% variables of full spectrum, calibration determination coefficient, and prediction determination coefficient reached 0.998 and 0.993 where the explained variance was increased by 27.30%. It could effectively extract variables related to the tested substance and provide a new variable selection method for near-infrared spectral analysis.
      PubDate: Tue, 10 May 2022 09:50:02 +000
       
  • A Raman Spectroscopic Study of Calcium Silicate Hydrate (CSH) in the
           Cement Matrix with CNTs and Oxide Additives

    • Abstract: The calcium silicate hydrate (CSH) concentration in the cement paste mixed with different types of carbon nanotubes (CNTs) and oxide additives is compared by using Raman spectroscopy. The pristine, hydroxyl and carboxyl functionalized CNTs are used in this work. The oxide additives are zinc oxide (ZnO), gadolinium oxide (Gd2O3), and silicon oxide (SiO2). A laser wavelength of 785 nm was used to collect the Raman spectra. It was observed that the concentration of calcium silicate hydrate (CSH) is unaffected in CNTs-OPC matrices regardless of the type and weight percentage of the CNTs. The oxides, as expected, show significant effects on the concentration of the CSH in the matrices. An increase in the CSH concentration is observed in the ZnO and Gd2O3 matrices with cement. For the SiO2 cement paste matrix, however, the CSH concentration appears to be decreased. This study shows CSH concentration can be controlled by using oxide additives whereas CNTs do not react chemically with the cement composites.
      PubDate: Tue, 26 Apr 2022 08:05:02 +000
       
  • Development of a Handheld System for Liquor Authenticity Detection Based
           on Laser Spectroscopy Technique

    • Abstract: In this paper, a handheld liquor authenticity detection system is demonstrated based on the laser spectroscopy technique, which consists of a handheld laser spectrometer and a mobile phone display terminal. In this system, the semiconductor laser is integrated into the spectrometer and the laser beam is further angled to the optical axis of the spectrometer to avoid interference of the fluorescence generated by the bottle wall. During the system operation, the laser excites the tested liquor to generate fluorescence and Raman spectroscopy signals, which are digitized and wirelessly transmitted by Wi-Fi to the Android mobile terminal. After the image processing by the mobile phone APP, the tested liquor spectrum curve is obtained. At the same time, based on the standard liquor spectrum curve stored in the database, the Pearson correlation coefficient is calculated and the matching similarity is given. In addition, this paper proposes a calibration method based on pure water Raman intensity to achieve accurate measurement of fluorescence intensity and minimize the influence of fluorescence intensity saturation on the measurement results. In the experiment, we measured the similarity of 12 brands of Chinese liquor by using our self-developed handheld laser spectrometer. Their authenticity of liquor could be given accurately and effectively.
      PubDate: Fri, 08 Apr 2022 10:50:01 +000
       
  • Investigation of Formalin-Fixed Tissue Optical Characteristics in the
           Range of 200–500 GHz Using Pulsed Terahertz Reflection Spectroscopy to
           Differentiate Oral Malignant, Benign, and Cyst

    • Abstract: The application of Terahertz electromagnetic waves to diagnose oral cancer was investigated. A single case of formalin-fixed oral squamous cell carcinoma (malignant), ameloblastoma (benign), and odontogenic keratocyst was examined using terahertz pulsed spectroscopy in the frequency span of 0.1–2 THz. The measured absorption coefficient, refractive index, and the extinction coefficient were reported to be high for malignant samples than benign and cyst. The THz results are validated with hematoxylin and eosin-stained microscopic images. The results demonstrate that the THz signal was shown to be consistently higher for the malignant sample compared to benign and the cyst. These results indicate that THz signals responded to the cell density by eliminating the effect of water.
      PubDate: Sun, 27 Feb 2022 10:35:01 +000
       
  • Quantitative Determination of Sucrose Adulterated in Red Ginseng by
           Terahertz Time-Domain Spectroscopy (THz-TDS) with Monte Carlo
           Uninformative Variable Elimination (MCUVE) and Support Vector Regression
           (SVR)

    • Abstract: This paper introduces a method to detect the content of sucrose, an adulterant of red ginseng, based on terahertz spectroscopy. Experiments were carried out on red ginseng with 6 levels of adulterated concentrations using terahertz time-domain spectroscopy (THz-TDS). We separately extracted the information of the terahertz spectral curve by principal component analysis (PCA) and Monte Carlo uninformative variable elimination (MCUVE) and then separately performed quantitative analysis by partial least squares regression (PLSR) and support vector regression (SVR). Because the nonlinear line factor in the terahertz spectral curve of red ginseng samples is considered, the MCUVE-SVR has high correlation coefficient (>0.99) and ratio prediction to deviation (>7.4), low root means square error of deviation (
      PubDate: Sun, 27 Feb 2022 10:35:01 +000
       
  • FTIR and Raman Spectroscopy Study of Soot Deposits Produced in the
           Infrared Multiphoton Dissociation of Vinyl Bromide

    • Abstract: Even at low concentrations, poly-aromatic hydrocarbons found in soot have substantial health implications. Soot deposits have been reported and studied using FTIR and Raman spectroscopy. Using a CO2 photolysis laser, the samples were obtained via infrared multiphoton dissociation (IRMPD) of vinyl bromide (VBr, C2H3Br) molecules. The solid deposit formed in the IRMPD of VBr when a relatively high fluence of the order of 204 J.cm−2 was analyzed by FTIR, and it was discovered that the majority of its composition is aromatic and aliphatic hydrocarbons. Significant fullerene-type carbonaceous soot particles are also found, which could correspond to C60 and C70 or other carbonaceous agglomerates of a higher order; however, the disappearance of this fullerene on Raman spectra cast doubt on this explanation. Our samples’ Raman spectroscopy has been compared to Tamor and Vassell’s research, which may indicate that they have a lesser degree of hardness and density than these authors’ results, indicating a larger hydrogen content in our samples. The optical gap has been calculated, yielding a very limited range of values ranging only between 1.0 and 1.2 eV, resulting in a crystalline size of 0.58 to 1.12 nm.
      PubDate: Fri, 25 Feb 2022 05:50:02 +000
       
  • A New Rule-Based Classification Method Using Shape-Based Properties of
           Spectral Curves

    • Abstract: Due to its high spatial and spectral information content, hyperspectral imaging opens up new possibilities for a better understanding of data and scenes in a wide variety of applications. An essential part of this process of understanding is the classification part. However, the high spatial and spectral resolution also leads to enormous amounts of data. The effective handling and use of such datasets for classification requires processing steps (dimensionality reduction through feature selection or feature extraction) that are not always goal-oriented. In this article, a new general classification approach is presented that uses the geometric shape of spectral signatures instead of purely statistical methods. In contrast to classical classification approaches (e.g., SVM, KNN), not only are reflectance values taken into account, but also parameters such as curvature points, curvature values, and the curvature behavior of spectral signatures are used to develop shape-describing rules in order to use them for classification by a rule-based procedure with IF-THEN queries. The flexibility and efficiency of the methodology are demonstrated on datasets from two different application domains and lead to convincing results with good performance.
      PubDate: Thu, 24 Feb 2022 08:50:01 +000
       
  • Feasibility of Individual Carotenoid Quantification in Mixtures Using
           UV-Vis Spectrophotometry with Multivariate Curve Resolution Alternating
           Least Squares (MCR-ALS)

    • Abstract: A fast and low-cost analytical method to determine the concentrations of carotenoids (β-carotene, lutein, and lycopene) from mixed standard solutions or from fruit extracts (kiwi fruits, tomato paste, pink grapefruit juice, kiwi-pineapple smoothie, and apricot nectar) was tested. The methodology was based on UV-Vis spectrophotometry and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). Results showed that relative concentrations of β-carotene, lutein, and lycopene in solvent were successfully determined by this technique with an error inferior to 6%. In real extracts, the procedure succeeded well in identifying the major carotenoid type of the fruit samples but also a more complex profile of a fruit mixture. The results also showed that accuracy of carotenoids determination by UV-Vis spectrophotometry-MCR-ALS in fruit extracts was conditioned by their spectral characteristics (III/II ratios and λmax), their relative proportion, and the extract purity.
      PubDate: Wed, 09 Feb 2022 05:35:04 +000
       
  • Comparison of Performance of Photodiodes with Different Active Areas Using
           Acrylic and Quartz Cuvettes for Spectrophotometry in Direct Measurements
           of Glucose in Water and Human Blood Plasma by Optical Means Using
           Near-Infrared

    • Abstract: Diabetes mellitus is one of the most relevant noncommunicable diseases; the WHO figures in its latest update that 422 million people suffer from it; additionally, it has remained for more than 20 years within the 10 main causes of death worldwide; this disease affects the population at any age; glucose measurement is used to assist the treatment of this disease by different methods that are classified as invasive, minimally invasive, and noninvasive, the latter being an area of recent development due that it is not traumatic for patients. This work consists of the experimental characterization of an optical system for plasma glucometry using near infrared by spectrophotometry. This glucometry system is based on the employ of an infrared LED with a wavelength of 1650 nm, a beam angle of 16°, and an output power of 1.6 mW that passes through the analyte (glucose in blood plasma) that is contained in cuvettes of different materials (acrylic and quartz) to subsequently affect a photodiode with different active areas ranging from 0.06 mm to 1.5 mm in order to evaluate the efficiency by comparing the sensitivity in the presence of glucose making additions ranging 100 mg/dl–1000 mg/dl within a dark chamber. The experiments showed that the use of photodiodes with a larger active area and the use of quartz cuvettes show a higher sensitivity compared to photodiodes with small active areas and the use of acrylic cuvettes. This configuration presented an R2 of 0.99 and a sensitivity of 0.225 mV/1 mg/dl of glucose; despite the fact that the initial voltage in each of the experimental repetitions varies, the downward voltage pattern is maintained; based on this, it is concluded that this method using this setup is feasible for plasma glucose measurement.
      PubDate: Fri, 04 Feb 2022 06:35:02 +000
       
  • Angle-Resolved Intensity of In-Axis/Off-Axis Polarized Micro-Raman
           Spectroscopy for Monocrystalline Silicon

    • Abstract: Monocrystalline silicon (c-Si) is still an important material related to microelectronics/optoelectronics. The nondestructive measurement of the c-Si material and its microstructure is commonly required in scientific research and industrial applications, for which Raman spectroscopy is an indispensable method. However, Raman measurements based on the specific fixed Raman geometry/polarization configuration are limited for the quantified analysis of c-Si performance, which makes it difficult to meet the high-end requirements of advanced silicon-based microelectronics and optoelectronics. Angle-resolved Raman measurements have become a new trend of experimental analysis in the field of materials, physics, mechanics, and optics. In this paper, the characteristics of the angle-resolved polarized Raman scattering of c-Si under the in-axis and off-axis configurations are systematically analyzed. A general theoretical model of the angle-resolved Raman intensity is established, which includes several alterable angle parameters, including the inclination angle, rotation angle of the sample, and polarization directions of the incident laser and scattered light. The diversification of the Raman intensity is given at different angles for various geometries and polarization configurations. The theoretical model is verified and calibrated by typical experiments. In addition, this work provides a reliable basis for the analysis of complex polarized Raman experiments on silicon-based structures.
      PubDate: Fri, 31 Dec 2021 06:50:08 +000
       
  • Investigation on the Binding and Conformational Change of
           All-trans-Retinoic Acid with Peptidyl Prolyl cis/trans Isomerase Pin1
           Using Spectroscopic and Computational Techniques

    • Abstract: Binding and conformational change of all-trans-retinoic acid (ATRA) with peptidyl prolyl cis/trans isomerase Pin1 were investigated systematically by spectroscopic and computational techniques under experimentally optimized physiological conditions. The intrinsic fluorescence of Pin1 was quenched through a static quenching mechanism in the presence of ATRA with binding constants on the order of 105 mol/L. Thermodynamic parameters (ΔH = 15.76 kJ/mol and ΔS = 158.36 J/mol·K at 293 K) and computational results illustrated that the hydrophobic interactions played a significant role in the binding process of ATRA to Pin1, but electrostatic forces, weak van der Waals, and hydrogen bonds cannot be ignored. Circular dichroism, fluorescence spectra, and computational simulations revealed that ATRA interacted with residues Lys63 and Arg69 of Pin1 to affect its conformational changes. Molecular dynamic simulation, principal component analysis, and free energy landscape monitored the dynamical conformational characteristics of ATRA binding to Pin1. All in all, the present research might provide a reference for the development and design of retinoic acid drugs that inhibit the activity of Pin1.
      PubDate: Thu, 16 Dec 2021 12:20:02 +000
       
  • Estimating the Ground and Excited State Dipole Moments of Levofloxacin and
           Norfloxacin Drugs Using Solvatochromic Effects and Computational Work

    • Abstract: Levofloxacin (LVF) and norfloxacin (NRF) are a group of fluoroquinolone antibiotics, broad spectrum used to treat various infections caused by many bacterial species. The drugs contain functional groups which control the type and degree of interaction with different solvents. In this research, the ground and excited state dipole moments of LVF and NRF drugs were estimated using solvatochromic effects and computational work. The dipole moments were estimated from absorption and emission spectra in polar and nonpolar solvents using Bakhshiev’s, Kawski–Chamma–Viallet, Lippert–Mataga, and Reichardt models. The results indicated the emission spectra are more strongly affected by solvent polarity than the absorption spectra. The calculated excited state dipole moment is larger than that of the ground state, indicating that the probe compounds are significantly more polarized in the excited state than in the ground state. From computational work, the HOMO-LUMO energy band gap, the dipole moments, electron charge density distribution, and oscillator strength were determined using the semiempirical MP6 method, DFT-B3LYP-6-31G, and DFT-B3LYP-3-21G employing Gaussian 09 software. In general, larger dipole moments were obtained by computation rather than from experiments due to the absence of solvent effects.
      PubDate: Fri, 10 Dec 2021 10:05:01 +000
       
  • Comparison of Machine Learning Classification Methods for Determining the
           Geographical Origin of Raw Milk Using Vibrational Spectroscopy

    • Abstract: One of the significant challenges in the food industry is the determination of the geographical origin, since products from different regions can lead to great variance in raw milk. Therefore, monitoring the origin of raw milk has become very relevant for producers and consumers worldwide. In this exploratory study, midinfrared spectroscopy combined with machine learning classification methods was investigated as a rapid and nondestructive method for the classification of milk according to its geographical origin. The curse of dimensionality makes some classification methods struggle to train efficient models. Thus, principal component analysis (PCA) has been applied to create a smaller set of features. The application of machine learning methods such as PLS-DA, PCA-LDA, SVM, and PCA-SVM demonstrates that the best results are obtained using PLS-DA, PCA-LDA, and PCA-SVM methods which show a correct classification rate (CCR) of 100% for PLS-DA and PCA-LDA and 94.95% for PCA-SVM, whereas the application of SVM without feature extraction gives a low CCR of 66.67%. These findings demonstrate that FT-MIR spectroscopy, combined with machine learning methods, is an efficient and suitable approach to classify the geographical origins of raw milk.
      PubDate: Wed, 08 Dec 2021 04:50:01 +000
       
  • Quantification of the Spectral Variability of Ore-Bearing Granodiorite
           under Supervised and Semisupervised Conditions: An Upscaling Approach

    • Abstract: Reflectance spectroscopy is a nondestructive, rapid, and easy-to-use technique which can be used to assess the composition of rocks qualitatively or quantitatively. Although it is a powerful tool, it has its limitations especially when it comes to measurements of rocks with a phaneritic texture. The external variability is reflected only in spectroscopy and not in the chemical-mineralogical measurements that are performed on crushed rock in certified laboratories. Hence, the spectral variability of the surface of an uncrushed rock will, in most cases, be higher than the internal chemical-mineralogical variability, which may impair statistical models built on field measurements. For this reason, studying ore-bearing rocks and evaluating their spectral variability in different scales is an important procedure to better understand the factors that may influence the qualitative and quantitative analysis of the rocks. The objectives are to quantify the spectral variability of three types of altered granodiorite using well-established statistical methods with an upscaling approach. With this approach, the samples were measured in the laboratory under supervised ambient conditions and in the field under semisupervised conditions. This study further aims to conclude which statistical method provides the best practical and accurate classification for use in future studies. Our results showed that all statistical methods enable the separation of the rock types, although two types of rocks have exhibited almost identical spectra. Furthermore, the statistical methods that supplied the most significant results for classification purposes were principal component analysis combined with k-nearest neighbor with a classification accuracy for laboratory and field measurements of 68.1% and 100%, respectively.
      PubDate: Mon, 06 Dec 2021 09:35:04 +000
       
  • Qualitative Discrimination of Intact Tobacco Leaves Based on Near-Infrared
           Technology

    • Abstract: To explore the application of near-infrared (NIR) technology to the quality analysis of raw intact tobacco leaves, a nondestructive discrimination method based on NIR spectroscopy is proposed. A “multiregion + multipoint” NIR spectrum acquisition method is developed, allowing 18 NIR diffuse reflectance spectra to be collected from an intact tobacco leaf. The spectral characteristics and spectral preprocessing methods of intact tobacco leaves are analyzed, and then different spectra (independent or average spectra) and different algorithms (discriminant partial least-squares (DPLS) and Fisher’s discriminant algorithms) are used to construct discriminant models for verifying the feasibility of intact leaf modeling and determining the optimal model conditions. Qualitative discrimination models based on the position, green-variegated (GV), and the grade of intact tobacco leaves are then constructed using the NIR spectra. In the application and verification stage, a multiclassification voting mechanism is used to fuse the results of multiple spectra from a single tobacco leaf to obtain the final discrimination result for that leaf. The results show that the position-GV discrimination model constructed using independent spectra and the DPLS algorithm and the grade discrimination model constructed using independent spectra and Fisher’s algorithm achieve optimal results with intact leaf NIR wavenumbers from 5006–8988 cm−1 and the first-derivative and standard normal variate transformation preprocessing method. Finally, when applied to new tobacco leaves, the position-GV model and the grade model achieve discrimination accuracies of 95.18% and 92.77%, respectively. This demonstrates that the two models have satisfactory qualitative discrimination ability for intact tobacco leaves. This study has established a feasible method for the nondestructive qualitative discrimination of the position, GV, and grade of intact tobacco leaves based on NIR technology.
      PubDate: Thu, 02 Dec 2021 12:20:01 +000
       
  • Applying Energy-Dispersive X-Ray Fluorescence Analysis to Detect Tungsten
           Inclusions in Nuclear Fuel Rod End Plug TIG Welds

    • Abstract: This study proposes a new method of detecting tungsten inclusions in nuclear fuel rod upper-end plug welds using energy-dispersive X-ray fluorescence (EDXRF) analysis. The Monte Carlo simulation method was used to simulate the process of detecting tungsten inclusions in nuclear fuel rod upper-end plug welds by the EDXRF. The detectable tungsten particle diameters in the zirconium alloy at different depths in welds and the detection limits of the trace tungsten dispersed in welds were obtained. Then, we constructed an experimental device that uses a CdTe detector with an X-ray tube. The results showed that the relative standard deviation of the net count rate of tungsten K-series characteristic X-rays [W (Kα)] was 1.46%, and the optimum parameters are a tube voltage of 150 kV and current of 0.5 mA. These values were used to perform energy-dispersive X-ray fluorescence analysis. These results were compared to the X-ray radiographic results, which were broadly similar. Furthermore, the results of EDXRF analysis were more legible and reliable than those from X-ray radiographic inspections. This study demonstrates the feasibility of applying EDXRF analysis to detect tungsten inclusions.
      PubDate: Fri, 26 Nov 2021 11:20:03 +000
       
  • Rapid Screening and Estimation of Binding Constants for Interactions of
           Fe3+ with Two Metalloproteins, Apotransferrin and Transferrin, Using
           Affinity Mode of Capillary Electrophoresis

    • Abstract: The interaction behavior of Fe3+ with transferrin and apotransferrin (iron-free form) was investigated in this study using affinity capillary electrophoresis. Change in the mass and charge of protein upon binding to the metal ion in the capillary tube led to variation in its migration time and was used to measure the noncovalent binding interactions by fast screening method. Acetanilide was used as the electroosmotic flow (EOF) marker to avoid possible errors due to the change in EOF during the experiment. The binding results were calculated from the mobility ratios of protein (Ri) and EOF marker (Rf) using the formula (Ri − Rf)/Rf or ∆R/Rf. For more comprehensive understanding, the kinetics of the interaction was studied and binding constants were calculated. Results showed that the Fe3+ displayed insignificant interaction with both proteins at lower metal ion concentrations (5–25 μmol/mL). However, transferrin exhibited significant interactions with the metal ion at 50 and 100 μmol/mL (ΔR/Rf = 0.0114 and 0.0201, resp.) concentrations and apotransferrin showed strong binding interactions (ΔR/Rf = −0.0254 and 0.0205, resp.) at relatively higher Fe3+ concentrations of 100 and 250 μmol/mL. The binding constants of 18.968 mmol−1 and −13.603 mmol−1 were recorded for Fe3+ interaction with transferrin and apotransferrin, respectively, showing significant interactions. Different binding patterns of Fe3+ with both proteins might be attributed to the fact that the iron-binding sites in transferrin have already been occupied, which was not the case in apotransferrin. The present study may be used as a reference for the investigation of protein-metal ion, drug-protein, drug-metal ion, and enzyme-metal ion interactions and may be helpful to provide preliminary insight into the new metal-based drug development.
      PubDate: Fri, 19 Nov 2021 08:50:02 +000
       
  • Spectral Characteristics of Needle Array-Plate Dielectric Barrier
           Discharge Plasma and Its Activated Water

    • Abstract: The plasma-activated water (PAW), as a new environmentally friendly nonthermal processing technology, has attracted wide attention for its applications in agriculture, food, and biomedical fields. This paper used the needle array-plate dielectric barrier discharge (needle array-plate DBD) device to activate deionized water and prepare PAW simply and efficiently. It was found that the concentration of reactive oxygen and nitrogen species (RONS) generated in the process of needle array-plate DBD was large and varied. Especially in the wavelength range of 600–770 nm, the spectral intensity is stronger. And, the ionic wind is more likely to interact with the deionized water. The changes in PAW parameters and UV/Vis spectra with treatment time were measured under different voltages and needle-dielectric plate distances. Results show that increasing discharge voltage or decreasing needle-dielectric plate distance increases the concentration of RONS, ionic wind speed, water evaporation, and conductivity of the PAW and decreases pH. UV/Vis spectra results show that prolonged treatment time results in increased total absorbance and concentrations of H2O2 and and that a new absorption peak appears at 210 nm in the UV/Vis spectra. When the wavelength is larger than 210 nm, a redshifted new peak and color enhancement are observed. The seeds of Astragalus adsurgens Pall were treated by discharge plasma, PAW, and the combination of plasma and PAW. It was found that high voltage and long-time activated PAW could significantly increase the ROS level of seeds and seedlings after germination for 3 days, resulting in oxidative stress damage. The survival rate of seeds was lower than that under the half lethal dose. This paper provides a feasible device design for treating activated water in large quantities with high efficiency, which is important for the application of PAW and mutation breeding of A. adsurgens Pall.
      PubDate: Mon, 01 Nov 2021 04:35:01 +000
       
  • Study of the Effects of Heating on Organic Matter and Mineral Phases in
           Limestones

    • Abstract: Color-induced changes in stones due to heating can be useful in determining the degree of degradation generated in their components and structure. We evaluate the effect of heating in three types of limestones, useful in building and restoration, corresponding to biomicrite (BC), biosparite (BS), and intramicrite (IM), in the range of temperature from 100°C to 600°C. Our analyses indicate that the strongest changes in reflectance occur in the samples of intramicrite, followed by biomicrite, being biosparite showing the smallest ones. Additionally, IM samples suffer the largest modifications in effective porosity due to the thermal treatment; in contrast, BS and BC samples show smaller temperature-induced alterations associated with smaller changes in reflectance. Moreover, we reveal that most of the thermally induced variations are associated, in this range of temperature, to the dehydroxylation of goethite that transforms into hematite, as well as by the burning and partial release of the organic matter present in the rock. Colorimetry analyses show that the sequence of thermally induced changes can be followed by the evolution of the three coordinates, L (lightness), a (red-green), and b (yellow-blue), of the CIE 1976 Lab space.
      PubDate: Fri, 29 Oct 2021 09:50:01 +000
       
  • Monitoring Sea Ice in Liaodong Bay of Bohai Sea during the Freezing Period
           of 2017/2018 Using Sentinel-2 Remote Sensing Data

    • Abstract: It is of great significance to monitor sea ice for relieving and preventing sea ice disasters. In this paper, the growth and development of sea ice in Liaodong Bay of Bohai Sea in China were monitored using Sentinel-2 remote sensing data during the freezing period from January to March in 2018. Based on the comprehensive analysis of the spectral characteristics of seawater and sea ice in visible bands, supplemented by the Normalized Difference Snow Index (NDSI) and the Normalized Difference Vegetation Index (NDVI), we proposed a new method based on decision tree classification for extracting sea ice types in Liaodong Bay of Bohai Sea. Using the remote sensing data of eight satellite overpasses acquired from Sentinel-2A/B satellites, the distribution and area of the different sea ice types in Liaodong Bay during the freezing period of 2017/2018 were obtained. Compared with the maximum likelihood (ML) classification method and the support vector machine (SVM) classification method, the proposed method has higher accuracy when discriminating the sea ice types, which proved the new method proposed in this paper is suitable for extracting sea ice types from Sentinel-2 optical remote sensing data in Liaodong Bay. And its classification accuracy reaches 88.05%. The whole process of evolution such as the growth and development of sea ice in Liaodong Bay during the freezing period from January to March in 2018 was monitored. The maximum area of sea ice was detected on 27 January 2018, about 10,187 km2. At last, the quantitative relationship model between the sea ice area and the mean near-surface temperature derived by MODIS data in Liaodong Bay was established. Through research, we found that the mean near-surface temperature was the most important factor for affecting the formation and melt of sea ice in Liaodong Bay.
      PubDate: Fri, 29 Oct 2021 06:05:01 +000
       
  • Experimental and Theoretical Investigations of Terahertz Spectra of the
           Structural Isomers: Mannose and Galactose

    • Abstract: The high-resolution terahertz spectra of the two structural isomers, mannose and galactose, have been measured by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.5–4.0 THz at room temperature. Significant differences between these similar molecules have been found in their THz characteristic spectra, implying that THz-TDS is a powerful tool for identifying isomers. Structural analyses and normal mode calculations of the two systems were performed using solid-state density functional theory (DFT) with the PBE and PW91 density functionals as well as using gas-state DFT with B3LYP hybrid functional. Among these calculations, the solid-state simulated results obtained from the PBE method exhibit a good agreement with the experimentally measured spectra. According to the calculated results of PBE, the observed spectral features were assigned as primarily external lattice translations, deformations, and rotations with lesser contributions due to intramolecular motion of pyranose ring, CH2OH group, and hydroxyl groups.
      PubDate: Tue, 26 Oct 2021 07:20:02 +000
       
  • Dynamic Variation in Hippocampal Metabolism after Acute Stress Exposure:
           An In Vivo Proton Magnetic Resonance Spectroscopy Study at 9.4 T

    • Abstract: An acute stress response is a complex process that activates the neuroendocrine and metabolic systems for homeostasis. A study on acute stress is important to understand how an organism adapts to stress for survival. However, most studies have focused on chronic stress, and there are few studies on acute stress. They have analyzed the metabolic alterations in the brain at a particular time after acute stress. This study explored the temporal variations of the brain metabolites in the hippocampus after acute restraint stress using proton magnetic resonance spectroscopy. All mice in the acute stress group were physically restrained for two hours in a 50 mL conical tube. A 9.4 T animal MRI and MRS scanner was used with point-resolved spectroscopy technique for data acquisition, which was repeated four times without interscan interval. Metabolites were quantified from the data using LCModel with a simulated basis set. Based on the change in concentration of metabolites, the data were statistically analyzed using two-way repeated-measures analysis of variance between groups and a support vector machine for all time points and Student’s t-test with FDR correction for each time point. The present study found that the differences between groups are significantly () presented in alanine and glutamate. The effect of time of the two metabolites significantly exists (): the first, second, and third time points in alanine and the first and second time points in glutamate. A combination of stress-specific metabolites (alanine, glutamate, N-acetyl-aspartate) that best reflect the influence of acute stress was determined using a support vector machine. These findings may indicate the importance of the timing of analysis after acute stress and provide new insights into a deeper understanding of acute stress response, including the molecular mechanism of stress-related disorders and stress resilience or vulnerability.
      PubDate: Wed, 20 Oct 2021 09:35:01 +000
       
  • LIBS Monitoring and Analysis of Laser-Based Layered Controlled Paint
           Removal from Aircraft Skin

    • Abstract: Reliability and controllability of selective removal of multiple paint layers from the surface of aircraft skin depend on effective online monitoring technology. An analysis was performed on the multi-pulse laser-induced breakdown spectroscopy (LIBS) on the surface of the aluminum alloy substrate, primer, and topcoat. Based on that, an exploration was conducted on the changes of the characteristic peaks corresponding to the characteristic elements that are contained in the topcoat, primer, and substrate with different layers of a laser action, in combination with analysis of microscopic morphology, composition, and depth of laser multi-pulse pits. The results show that the appearance and increase of the characteristic peak intensity of the Ca I at the wavelength of 422.7 nm can be regarded as the basis for the complete removal of the topcoat; the decrease or disappearance of the characteristic peak intensity can be regarded as the basis for the complete removal of the primer. Al I spectrum at the wavelength of 394.5 nm and 396.2 nm can be adopted to characterize the degree of damage to the aluminum alloy substrate. The feasibility and accuracy of the LIBS technology for the laser selective paint removal process and effect monitoring of aircraft skin were verified. Demonstrating that under the premise of not damaging the substrate, laser-based layered controlled paint removal (LLCPR) from aircraft skin can be achieved by monitoring the spectrum and composition change law of specified wavelength position corresponding tothe characteristic elements that are contained in the specific paint layer.
      PubDate: Thu, 30 Sep 2021 14:35:02 +000
       
  • Soil Classification Based on Deep Learning Algorithm and Visible
           Near-Infrared Spectroscopy

    • Abstract: Changes in land cover will cause the changes in the climate and environmental characteristics, which has an important influence on the social economy and ecosystem. The main form of land cover is different types of soil. Compared with traditional methods, visible and near-infrared spectroscopy technology can classify different types of soil rapidly, effectively, and nondestructively. Based on the visible near-infrared spectroscopy technology, this paper takes the soil of six different land cover types in Qingdao, China orchards, woodlands, tea plantations, farmlands, bare lands, and grasslands as examples and establishes a convolutional neural network classification model. The classification results of different number of training samples are analyzed and compared with the support vector machine algorithm. Under the condition that Kennard–Stone algorithm divides the calibration set, the classification results of six different soil types and single six soil types by convolutional neural network are better than those by the support vector machine. Under the condition of randomly dividing the calibration set according to the proportion of 1/3 and 1/4, the classification results by convolutional neural network are also better. The aim of this study is to analyze the feasibility of land cover classification with small samples by convolutional neural network and, according to the deep learning algorithm, to explore new methods for rapid, nondestructive, and accurate classification of the land cover.
      PubDate: Fri, 03 Sep 2021 13:20:00 +000
       
  • Spatial Differentiation Analysis of Water Quality in Dianchi Lake Based on
           GF-5 NDVI Characteristic Optimization

    • Abstract: Remote sensing monitoring of aquatic vegetation is critical to the water quality evaluation of plateau lakes. To obtain a clear understanding of the water environment status of Dianchi Lake, a GF-5 hyperspectral characteristics-based optimal NDVI approach was employed to quantify the aquatic vegetation cover and analyze water quality. By characteristic bands recognition, the optimal NDVI was obtained; the spatial distribution of aquatic plants and water quality in Dianchi Lake were then analyzed. Results showed the following: (1) For Caohai, the optimal NDVI value was calculated by B86 in the red band range and B151 in the near-infrared band range, which achieve the best spectral response. For Waihai, the respective bands were B86 in the red band range and B99 in the near-infrared band range. (2) We also found significant regional differences in aquatic plants distribution for the study area. Caohai was dominated by aquatic plants and high-quality water areas only occurred in the northern tip. While the situation for Waihai was much optimistic, areas with poor water quality were mainly found in the north and south parts. Water quality also showed a descending trend from the lakeside zone to the lake center. (3) By comparing to previous studies, we concluded that policy interventions and water protection measures carried out by the government during the past years are extremely effective. The optimal NDVI method provides a reliable evaluation and is potentially transferable to other plateau lake areas as a robust approach for the rapid assessment of water quality.
      PubDate: Thu, 26 Aug 2021 06:50:03 +000
       
  • Evaluation of the Effectiveness of Multiple Machine Learning Methods in
           Remote Sensing Quantitative Retrieval of Suspended Matter Concentrations:
           A Case Study of Nansi Lake in North China

    • Abstract: Total suspended matter (TSM) is a core parameter in the quantitative retrieval of ocean color remote sensing and an important indicator for evaluating the quality of the aquatic environment. This study selects part of Nansi Lake in North China as the study area. Researchers used Hyperion remote sensing data and field-measured TSM concentration as data sources. Firstly, the characteristic variables with high correlation were selected based on spectral analysis. Then, seven methods such as linear regression, BP neural network (BP), KNN, random forest (RF), and random forest based on genetic algorithm optimization (GA_RF) are used to construct the inversion model of TSM concentration. The retrieval accuracy of each model shows that the machine learning models are much more accurate than the linear model. Among them, the GA_RF model retrieves the suspended solids concentration with the best performance and the highest prediction accuracy, with a determination coefficient R2 of 0.98, a root mean square error (RMSE) of 1.715 mg/L, and an average relative error (ARE) of 6.83%. Additionally, the spatial distribution of TSM concentration was inversed by Hyperion remote sensing image. The results showed that the concentration of TSM was lower in the northwest and higher in the southeast, and the concentration distribution was uneven, showing the characteristics of a typical shallow macrophytic lake. This study provides an effective method for monitoring TSM concentration and other water quality parameters in the shallow macrophytic lake and further proves the advantages of machine learning in ocean color inversion. All in all, this research provides some useful methods and suggestions for quantitative inversion of TSM concentration in shallow macrophytic lakes.
      PubDate: Sat, 14 Aug 2021 06:20:13 +000
       
  • Destabilization of Immersed Dense Granular Material Submitted to Localized
           Fluidization: An Experimental and Numerical Study

    • Abstract: An alternative experimental approach and a numerical analysis for the study of destabilization by localized fluidization of an immersed dense granular material are presented. To visualize the evolutions of the internal structure of the granular medium, the hydrogel beads, composed of about 99% of water and having substantially the same refraction indexes, are used as solid phase. A LED lighting system is used in place of a laser lighting system. As a result, the optical access restriction of porous structure is removed. A real economic alternative for the experimental study of fluid-grain coupling during destabilization by localized fluidization of a granular material is created. The experimental phenomenology presented in the literature is verified: the system passes successively through three different stationary regimes: static regime, fluidized cavity regime, and fluidized chimney regime. Some restrictions of using hydrogel beads as particles in the study of liquid-solid interaction are also discussed.
      PubDate: Tue, 27 Jul 2021 07:20:01 +000
       
 
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