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The influence on sample preparation on spectral induced polarization of unconsolidated sediments
摘要： Spectral induced polarization (SIP) measurements in the laboratory are in many cases intended to provide representative and comparable results of complex electrical conductivity. This is not invariably the case when using unconsolidated sediments, as the sample preparation influences several SIP-relevant properties of the samples, including the pore geometry. The pore space is supposed to control the polarization effect and therefore a change in the pore space will change the measured parameters. We analysed the influence of the sample preparation on SIP measurements by testing various filling methods, each defined by a sequence of particular steps, with regard to the reproducibility of the spectra. The measurements were performed on three different sample materials. Variations of the spectra due to different filling methods were obtained, indicating the importance of considering the sample preparation. Methods that improved the reproducibility compared to loose packing of the samples were found, but the most suitable packing procedure depended on the material properties. The mean relaxation times and normalized chargeabilities were obtained from a Debye decomposition. Although unidentified processes caused scattering of the measured parameters, a relation of the IP-parameters to the porosities was present. A decrease of the porosity reduced both the relaxation times and the normalized chargeabilities.
关键词： Debye decomposition,sample preparation,unconsolidated sediments,reproducibility,spectral induced polarization,porosity
更新于2025-09-23 15:22:29
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Infrared characteristics of satellite based on bidirectional reflection distribution function
摘要： With the development of space industry, the requirements of space monitoring technology are becoming higher and higher. The infrared characteristics of on-orbit satellite were studied based on the satellite's flying attitude, background, material and orbit, etc. Bidirectional reflection distribution function (BRDF) was introduced to describe the characteristics of infrared reflection of the element, and a mathematical model of reflected radiation was established by summing the reflection of elements. The accuracy of the Torrance-Sparrow model was verified based on the measured data of the BRDF of the satellite's material. The relationship between the spectral radiance of satellite and the angle of observation was discussed. By comparing the differences in the variation of reflected solar radiance with flight period and the distribution of the radiant intensity between the diffuse reflection model and the BRDF model, the result is analyzed that the BRDF model which based on the reflection of the material can better reflect the characteristics of infrared radiation of satellite.
关键词： BRDF,Spectral radiance,Diffuse reflection,Satellite
更新于2025-09-23 15:22:29
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Reproducibility of Disc and Macula Optical Coherence Tomography using the Canon OCT-HS100 as Compared with the Zeiss Cirrus HD-OCT
摘要： Purpose: In a clinical setting, the usefulness of optical coherence tomography (OCT) is strongly dependent on reproducibility of the measurement. The aim of the present study was to evaluate macula and optic disc measurement reproducibility with the new spectral-domain OCT (SD-OCT) from Canon (Canon OCT-HS100) and to compare reproducibility and obtained measurements with the Zeiss Cirrus HD-OCT. Methods: Macula and optic disc parameters from the right eyes of 31 subjects were obtained twice with both instruments. Interoperator reproducibility was evaluated by use of the coefficient of repeatability (CR), and the obtained measurements were compared between the instruments. Results: No difference in interoperator reproducibility could be found when comparing the 2 instruments and reproducibility ranged from 3.94% to 12.77% for optic disc parameters and from 1.19% to 3.54% for macula parameters. The lowest reproducibility was found for cup volume and vertical cup/disc ratio with both instruments. For all macula and retinal nerve fiber layer (RNFL) thickness measurements, there was a statistical difference when comparing the 2 instruments, except for RFNL measurements of the superior quadrant, with the Canon OCT-HS100 always evaluating the thickness to be thicker; however, the 2 instruments correlated well. Conclusions: The Canon OCT-HS100 is a reproducible instrument that matches the Zeiss Cirrus HD-OCT well. It remains to be evaluated how sensitive the Canon OCT-HS100 is to detect small subtle changes in optic disc parameters and macular nerve fiber layer thickness. Furthermore, due to the differences in thickness estimation, it is important to emphasize that SD-OCTs are not interchangeable.
关键词： Canon OCT-HS100,Reproducibility,Spectral domain,Optical coherence tomography
更新于2025-09-23 15:22:29
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Template Synthesis, Spectral, Thermal and Glucose Sensing of Pr3+ Complexes of Metformin Schiff-Bases
摘要： Schiff-bases of metformin with each of salicylaldehyde (HL1); 2,3-dihydroxybenzaldehyde (H2L2); 2,4-dihydroxybenzaldehyde (H2L3); 2,5-dihydroxybenzaldehyde (H2L4); 3,4-dihydroxybenzaldehyde (H2L5) and 2-hydroxynaphthaldehyde (HL6) and their complexes with Pr(III) were synthesized by template reaction. The complexes were characterized through elemental analysis, conductivity and magnetic moment measurements, IR, UV-Vis., fluorescence, GC-MS and XRD spectroscopy. The complexes exhibit a series of characteristic emission bands for Pr3+ ion in the 481-472 and 590-580 nm range with a 318-332 nm excitation source. The complexes have eight coordinated structure with the formulae [PrL1-4,6(NO3)2(H2O)3].nH2O where n = 1, 1?, 3, 4, 4 and [PrL5(NO3)(H2O)5].2H2O. The suggested stereochemistry was confirmed using TGA, DTG and DTA analysis and a mechanism for thermal decomposition was proposed. Coates-Redfern equation was used to calculate kinetic and thermodynamic parameters of the main decomposition step. The utility of the complexes towards the detection of glucose at physiologically relevant pH in phosphate buffer using UV-Vis and fluorescence spectroscopy as well as viscosity measurements are tried where the association constants were calculated.
关键词： Pr(III) complexes,Spectral and thermal properties,Glucose sensing,Metformin Schiff-bases
更新于2025-09-23 15:22:29
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Material Decomposition in X-ray Spectral CT Using Multiple Constraints in Image Domain
摘要： X-ray spectral CT appears as a new promising imaging modality for the quantitative measurement of materials in an object, compared to conventional energy-integrating CT or dual energy CT. We consider material decomposition in spectral CT as an overcomplete ill-conditioned inverse problem. To solve the problem, we make full use of multi-dimensional nature and high correlation of multi-energy data and spatially neighboring pixels in spectral CT. Meanwhile, we also exploit the fact that material mass density has limited value. The material decomposition is then achieved by using bounded mass density, local joint sparsity and structural low-rank (DSR) in image domain. The results on numerical phantom demonstrate that the proposed DSR method leads to more accurate decomposition than usual pseudo-inverse method with singular value decomposition (SVD) and current popular sparse regularization method with (cid:2)1-norm constraint.
关键词： Sparse representation,X-ray spectral CT,Material decomposition,Low-rank representation
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Compressive Hyperspectral Imaging and Super-resolution
摘要： Coded aperture snapshot spectral imager (CASSI) has been a popular spectral imaging architecture for its ability of capturing hyperspectral temporal resolution. However, such snapshot imaging system entails a large sacrifice in the spatial resolution of the data cube, since only a small amount of light gets into the imager during one snapshot. Also, the spatial resolution of the CASSI system is limited by the pixel size (and amount) of the detector, while it is difficult to fabricate a dense detector with small pixel size, especially for infrared spectral bands. Super-resolution is an advanced post-processing technique to alleviate such problem by exploiting the prior information of the image. In this letter, we try to realize image super-resolution from the perspective of developing new form of measurements by taking advantage of a modified CASSI system equipped with a coded aperture with higher spatial resolution than the detector, merging the SR model into the hardware configuration. Then the original data cube can be reconstructed from lower resolution measurements, thus the super-resolution is realized during the compressive sensing reconstruction process. The new system can be achieved based on the classical CASSI architecture in two dual ways, one by replacing the coded aperture with a higher resolution one and the other by substituting the focal plane array (FPA) detector with a lower resolution one. The experiments show that, we can recover images of higher quality with the first modification of CASSI system above, simply using a higher resolution coded aperture.
关键词： super resolution,compressive sensing,spectral imaging
更新于2025-09-23 15:22:29
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Optimising porous silicon Bragg reflectors for narrow spectral resonances
摘要： Achieving sharp spectral resonances in porous silicon based photonic structures is of significant practical importance for improving the accuracy of refractive index-based sensing in chemical and biochemical applications. Here, we show that by compensating for depth related heterogeneities in the etching conditions, we are able to reduce the porosity modulation in Bragg reflectors to below 1% and achieve absorption limited spectral widths of 7 nm in the visible part of the spectrum. Such narrowband Bragg reflectors provide markedly improved sensing capability for real-time monitoring of refractive index changes compared with reflectors with broader spectral features.
关键词： optical sensing,porous silicon,Bragg reflectors,narrow spectral resonances,refractive index-based sensing
更新于2025-09-23 15:21:21
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Streamlining volumetric multi-channel image cytometry using hue-saturation-brightness-based surface creation
摘要： Image cytometry is the process of converting image data to flow cytometry-style plots, and it usually requires computer-aided surface creation to extract out statistics for cells or structures. One way of dealing with structures stained with multiple markers in three-dimensional images, is carrying out multiple rounds of channel co-localization and image masking before surface creation, which is cumbersome and laborious. We propose the application of the hue-saturation-brightness color space to streamline this process, which produces complete surfaces, and allows the user to have a global view of the data before flexibly defining cell subsets. Spectral compensation can also be performed after surface creation to accurately resolve different signals. We demonstrate the utility of this workflow in static and dynamic imaging datasets of a needlestick injury on the mouse ear, and we believe this scalable and intuitive approach will improve the ease of performing histocytometry on biological samples.
关键词： spectral compensation,image cytometry,surface creation,hue-saturation-brightness,histocytometry
更新于2025-09-23 15:21:21
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Highly tunable multiple narrow emissions of dyed dielectric-metal core-shell resonators: towards efficient fluorescent labels
摘要： We report a potential efficient fluorescent label based on the dyed dielectric-metal core-shell resonators. By utilizing the near-field coupling between the dyes and the multipolar sharp cavity plasmon resonances, the dyed dielectric-metal core-shell resonators with diameter of 1.02 μm are demonstrated to be capable of supporting multiple spontaneous emission peaks with the linewidths as narrow as ~ 10 nm in visible range, and these reshaped fluorescent emissions are insensitive to the surrounding dielectric environment. Furthermore, these multiple narrow emission peaks show a precise tunability on the spectrum by simply separating a nanometric dielectric layer between the dielectric core and the metallic shell, which may provide an attractive spectral multiplexing strategy in the fields of cell biology and medical sciences.
关键词： spectral multiplexing,cavity plasmons,fluorescent label,dyed dielectric-metal core-shell resonators,quality factor
更新于2025-09-23 15:21:21
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Broad Range and High Precision Self-Mixing Interferometer Based on Spectral Analysis with Multiple Reflections
摘要： In this paper, a novel self-mixing interferometer is proposed with spectral analysis by multiple reflection vibration technique. The relationship between the vibration amplitude, the dominant frequency and the reflection time is deduced, which indicates that the theoretical minimum measurable vibration amplitude is 0.21λ/G(N,θ) and the precision is about 0.08λ/G(N,θ). The displacement sensitivity gain G(N,θ) increases with the reflection time. Theoretical analysis results show that the proposed method for vibration measurement has the advantages of high precision and broad measurement range, especially for the measurement of amplitude much smaller than λ/2. The validity of the method is tested by several experiments with different amplitudes and reflection times. An amplitude of 75 nm has been proved to be measurable and the absolute error is 5.43 nm, which is within the theoretical error range. The proposed method plays an important role in high precision and nanoscale measurement.
关键词： self-mixing,multiple reflections,spectral analysis
更新于2025-09-23 15:21:21