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Identification of train loads from the dynamic responses of an integrated sleeper in situ

JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES 2020年第11期31卷 1430-1440页

作者： Tran, Le-Hung Hoang, Tien Foret, Gilles Duhamel, Denis Messad, Samir Loaec, Arnaud Univ Gustave Eiffel Lab Navier CNRS Ecole Ponts ParisTechUMR 8205 F-77455 Champs Sur Marne 2 Marne La Vallee France SATEBA Courbevoie France

The monitoring of railway tracks can be performed through several measurement techniques. Recently, a method of diagnosing the railway track has been proposed using fiber Bragg gratings integrated inside the railway sleeper. An analytical model for the dynamics of railway sleepers has been developed allowing calculation of the sleeper responses. In this model, using the relation between the rail forces and displacements of a periodically supported beam, the sleeper's dynamic equation is written with the help of the Euler-Bernoulli beam and Dirac's delta distribution. Subsequently, the sleeper dynamic responses are calculated using the Green's function. This article presents an application of this model to identify the train loads from the strains measured in situ. Based on this model, we can obtain a matrix which presents the link between the loads and the sleeper responses. Then, by substituting the Fourier transform of measured strains at the middle and at the two rail seats of the sleeper, the train loads can be quickly calculated by inverting the matrix with the help of MATLAB. This method is validated by the experiments. Numerical examples with the measurement in situ are presented to show identified wheel loads from experimental signals.

关键词： Railway dynamics instrumented sleeper fiber Bragg gratings Green's function computation methods

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Efficient coupling into and out of high-Q resonators

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第8期21卷 1512-1517页

作者： Harbers, R Moll, N Erni, D Bona, GL Bächtold, W Swiss Fed Inst Technol Lab Electromagnet Fields & Microwave Elect CH-8092 Zurich Switzerland IBM Res Corp Zurich Res Lab CH-8803 Ruschlikon Switzerland

The temporal-coupled-mode theory is directly applied to the design of devices that feature a resonator with a high quality factor. For the temporal-coupled-mode theory we calculate the decay rate of the resonator to determine the transmission properties of the device. The analysis using the decay rates requires little computational effort, and therefore the optimum device properties can be determined quickly. Two examples, a wavelength filter and a resonator crossing, are presented to illustrate the use of the analysis. (C) 2004 Optical Society of America.

关键词： computation methods Optical resonators Photonic crystals Refractive index Transmission coefficient Wavelength filtering devices

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Toward a quantitative method for estimating tumour-stroma ratio in breast cancer using polarized light microscopy

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BIOMEDICAL OPTICS EXPRESS 2021年第6期12卷 3241-3252页

作者： Sprenger, Jillian Murray, Ciara Lad, Jigar Jones, Blake Thomas, Georgia Nofech-Mozes, Sharon Khorasani, Mohammadali Vitkin, Alex Univ Toronto Dept Med Biophys Toronto ON Canada Univ Hlth Network Lab Med Program Toronto ON Canada Univ Toronto Dept Lab Med & Pathobiol Toronto ON Canada Univ British Columbia Dept Surg Victoria BC Canada Univ Hlth Network Princess Margaret Canc Ctr Div Biophys & Bioimaging Toronto ON Canada Univ Toronto Dept Radiat Oncol Toronto ON Canada

The tumour-stroma ratio (TSR) has been explored as a useful source of prognostic information in various cancers, including colorectal, breast, and gastric. Despite research showing potential prognostic utility, its uptake into the clinic has been limited, in part due to challenges associated with subjectivity, reproducibility, and quantification. We have recently proposed a simple, robust, and quantifiable high-contrast method of imaging intra- and peri-tumoural stroma based on polarized light microscopy. Here we report on its use to quantify TSR in human breast cancer using unstained slides from 40 patient samples of invasive ductal carcinoma (IDC). Polarimetric results based on a stromal abundance metric correlated well with pathology designations, showing a statistically significant difference between high- and low-stroma samples as scored by two clinical pathologists. The described polarized light imaging methodology shows promise for use as a quantitative, automatic, and standardizable tool for quantifying TSR, potentially addressing some of the challenges associated with its current estimation.

关键词： computation methods Image analysis Microscopy Polarimetric imaging Polarized light Tissue

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Deep speckle reassignment: towards bootstrapped imaging in complex scattering states with limited speckle grains

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OPTICS EXPRESS 2023年第12期31卷 19588-19603页

作者： Zhu, Shuo Guo, Enlai Zhang, Wenjun Bai, Lianfa Liu, Honglin Han, Jing Nanjing Univ Sci & Technol Jiangsu Key Lab Spectral Imaging & Intelligent Sen Nanjing 210094 Peoples R China Chinese Acad Sci Shanghai Inst Opt & Fine Mech Key Lab Quantum Opt Shanghai 201800 Peoples R China

Optical imaging through scattering media is a practical challenge with crucial applications in many fields. Many computational imaging methods have been designed for object reconstruction through opaque scattering layers, and remarkable recovery results have been demonstrated in the physical models or learning models. However, most of the imaging approaches are dependent on relatively ideal states with a sufficient number of speckle grains and adequate data volume. Here, the in-depth information with limited speckle grains has been unearthed with speckle reassignment and a bootstrapped imaging method is proposed for reconstruction in complex scattering states. Benefiting from the bootstrap priors-informed data augmentation strategy with a limited training dataset, the validity of the physics-aware learning method has been demonstrated and the high-fidelity reconstruction results through unknown diffusers are obtained. This bootstrapped imaging method with limited speckle grains broadens the way to highly scalable imaging in complex scattering scenes and gives a heuristic reference to practical imaging problems.

关键词： computation methods Image quality Optical imaging Scattering media Speckle noise Speckle patterns

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Optical spectroscopy detects histological hallmarks of pancreatic cancer

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OPTICS EXPRESS 2009年第20期17卷 17502-17516页

作者： Wilson, Robert H. Chandra, Malavika Scheiman, James Simeone, Diane McKenna, Barbara Purdy, Julianne Mycek, Mary-Ann Univ Michigan Appl Phys Program Ann Arbor MI 48109 USA Univ Michigan Dept Internal Med Ann Arbor MI 48109 USA Univ Michigan Ctr Comprehens Canc Ann Arbor MI 48109 USA Univ Michigan Dept Surg Ann Arbor MI 48109 USA Univ Michigan Dept Pathol Ann Arbor MI 48109 USA Univ Michigan Dept Biomed Engn Ann Arbor MI 48109 USA

An empirical model was developed to interpret differences in the experimentally measured reflectance and fluorescence spectra of freshly excised human pancreatic tissues: normal, adenocarcinoma, and pancreatitis (inflammation). The model provided the first quantitative links between spectroscopic measurements and histological characteristics in the human pancreas. The reflectance model enabled the first (to our knowledge) extraction of wavelength resolved absorption and reduced scattering coefficients for normal and diseased human pancreatic tissues. The fluorescence model employed reflectance information to extract attenuation free "intrinsic" endogenous fluorescence spectra from normal pancreatic tissue, pancreatic adenocarcinoma, and pancreatitis. The method developed is simple, intuitive, and potentially useful for a range of applications in optical tissue diagnostics. This approach is potentially applicable to in vivo studies, because it can account for the absorptive effects of blood in tissues. (C) 2009 Optical Society of America

关键词： computation methods Forward scattering Mie theory Optical potentials Optical spectroscopy Photon migration

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LED near-eye holographic display with a large non-paraxial hologram generation

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OPTICS EXPRESS 2022年第24期30卷 43551-43565页

作者： Kozacki, Tomasz Chlipala, Maksymilian Martinez-Carranza, Juan Kukolowicz, Rafal Idicula, Moncy Sajeev Warsaw Univ Technol Inst Micromech & Photon 8 Sw A Boboli St PL-02525 Warsaw Poland

In this paper, two solutions are proposed to improve the quality of a large image that is reconstructed in front of the observer in a near-eye holographic display. One of the proposed techniques, to the best of our knowledge, is the first wide-angle solution that successfully uses a non-coherent LED source. It is shown that the resulting image when employing these types of sources has less speckle noise but a resolution comparable to that obtained with coherent light. These results are explained by the developed theory, which also shows that the coherence effect is angle varying. Furthermore, for the used pupil forming display architecture, it is necessary to compute a large virtual nonparaxial hologram. We demonstrate that for this hologram there exists a small support region that has a frequency range capable of encoding information generated by a single point of the object. This small support region is beneficial since it enables to propose a wide-angle rigorous CGH computational method, which allows processing very dense cloud of points that represents three-dimensional objects. This is our second proposed key development. To determine the corresponding support region, the concept of local wavefront spatial curvature is introduced, which is proportional to the tangent line to the local spatial frequency of the spherical wavefront. The proposed analytical solution shows that the size of this area strongly depends on the transverse and longitudinal coordinate of the corresponding object point. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： computation methods Holographic displays Holographic optical elements Image quality Light sources Speckle noise

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Improved full analytical polygon-based method using Fourier analysis of the three-dimensional affine transformation

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APPLIED OPTICS 2014年第7期53卷 1354-1362页

作者： Pan, Yijie Wang, Yongtian Liu, Juan Li, Xin Jia, Jia Beijing Inst Technol Beijing Engn Res Ctr Mixed Real & Adv Display Sch Optoelect Beijing 100081 Peoples R China Virginia Tech Bradley Dept Elect & Comp Engn Blacksburg VA 24061 USA Tsinghua Univ State Key Lab Precis Measurement Technol & Instru Beijing 100084 Peoples R China

Previous research [Appl. Opt. 52, A290 (2013)] has revealed that Fourier analysis of three-dimensional affine transformation theory can be used to improve the computation speed of the traditional polygonbased method. In this paper, we continue our research and propose an improved full analytical polygonbased method developed upon this theory. Vertex vectors of primitive and arbitrary triangles and the pseudo-inverse matrix were used to obtain an affine transformation matrix representing the spatial relationship between the two triangles. With this relationship and the primitive spectrum, we analytically obtained the spectrum of the arbitrary triangle. This algorithm discards low-level angular dependent computations. In order to add diffusive reflection to each arbitrary surface, we also propose a whole matrix computation approach that takes advantage of the affine transformation matrix and uses matrix multiplication to calculate shifting parameters of similar sub-polygons. The proposed method improves hologram computation speed for the conventional full analytical approach. Optical experimental results are demonstrated which prove that the proposed method can effectively reconstruct three-dimensional scenes. (c) 2014 Optical Society of America

关键词： Analytical techniques computation methods Diffraction theory Diode pumped lasers Holographic displays Matrix methods

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PHOTOMETRIC STEREO UNDER A LIGHT-SOURCE WITH ARBITRARY MOTION

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 1994年第11期11卷 3079-3089页

作者： HAYAKAWA, H ATR Human Information Processing Research Laboratories 2-2 Hikaridai Seika-cho Soraku-gun Kyoto 619-02 Japan

A new photometric-stereo method for estimating the surface normal and the surface reflectance of objects without a priori knowledge of the light-source direction or the light-source intensity is proposed. First, I construct a p x f image data matrix I from p pixel image intensity data through f frames by moving a light source arbitrarily. Under the Lambertian assumption the image data matrix I can be written as the product of two matrices S and L, with S representing the surface normal and the surface reflectance and L representing the light-source direction and the Light-source intensity. Using this formulation, I show that the image data matrix I is of rank 3. On the basis of this observation, I use a singular-value decomposition technique and useful constraints to factorize the image data matrix. This method can also be used to treat cast shadows and self-shadows without assumptions. The effectiveness of this method is demonstrated through performance analysis, laboratory experiment, and out-of-laboratory experiment.

关键词： computation methods Computer simulation Industrial inspection Light sources Matrix methods Motion estimation

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Narrow-band wavelength tunable filter based on asymmetric double layer metallic grating

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OPTICS EXPRESS 2015年第11期23卷 14434-14445页

作者： Liang, Yuzhang Peng, Wei Lu, Mengdi Chu, Shuwen Dalian Univ Technol Coll Phys & Optoelect Engn Dalian 116024 Peoples R China

In this paper, the optical properties of asymmetric double layer metallic gratings are presented theoretically. The asymmetric structure is achieved by two main factors: one corresponding to moving alternatively metal nanowires of the top layer metallic grating, the other corresponding to possessing different thickness of the top and down layer metallic gratings. Our proposed structure shows one remarkable narrow-band transmission dip at normal incidence, which is distinct different from that of symmetric structure. The results are further confirmed by using different numerical computation methods, and explained by the analytical model of Fano-like resonance. We find that, only when the thickness of the down layer metallic grating has certain fixed value, transmission dip can be transformed from two to only one dip even if the existence of symmetry breaking. However, the wavelength position of the dip can be easily controlled by adjusting the thickness of the top layer metallic grating without the need to modify the structure period, and the width of metal nanowire. Moreover, the influence of other structure parameters on the dip is also investigated. Surprisingly, in order to keep the appearance of one dip in the transmission spectrum of designed structure, there is a good linear approximation between the refractive index of waveguide layer and the thickness of down layer metallic grating, and the relation of waveguide layer thickness and the thickness of down layer metallic grating satisfy secondary polynomial fitting. This work can be used to develop subwavelength metallic-grating-based and narrow-band tunable wavelength filters. (C) 2015 Optical Society of America

关键词： Bandpass filters computation methods Fano resonance Guided mode resonance Refractive index Tunable filters

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Modeling optical properties of particles with small-scale surface roughness: combination of group theory with a perturbation approach

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OPTICS EXPRESS 2011年第12期19卷 11138-11151页

作者： Kahnert, Michael Rother, Tom Swedish Meteorol & Hydrol Inst Res Dept S-60176 Norrkoping Sweden German Aerosp Ctr DLR D-17235 Neustrelitz Germany

A T-matrix method for scattering by particles with small-scale surface roughness is presented. The method combines group theory with a perturbation expansion approach. Group theory is found to reduce CPU-time by 4-6 orders of magnitude. The perturbation expansion extends the range of size parameters by a factor of 5 compared to non-perturbative methods. An application to optically hard particles shows that small-scale surface roughness changes scattering in side-and backscattering directions, and it impacts the single-scattering albedo. This can have important implications for interpreting remote sensing observations, and for the climate impact of mineral aerosols. (C) 2011 Optical Society of America

关键词： computation methods Electromagnetic scattering Light wavelength Particle scattering Refractive index Remote sensing

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