- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Learning compact q-space representations for multi-shell diffusion-weighted MRI
摘要： Diffusion-weighted MRI measures the direction and scale of the local diffusion process in every voxel through its spectrum in q-space, typically acquired in one or more shells. Recent developments in microstructure imaging and multi-tissue decomposition have sparked renewed attention in the radial b-value dependence of the signal. Applications in motion correction and outlier rejection therefore require a compact linear signal representation that extends over the radial as well as angular domain. Here, we introduce SHARD, a data-driven representation of the q-space signal based on spherical harmonics and a radial decomposition into orthonormal components. This representation provides a complete, orthogonal signal basis, tailored to the spherical geometry of q-space and calibrated to the data at hand. We demonstrate that the rank-reduced decomposition outperforms model-based alternatives in human brain data, whilst faithfully capturing the micro- and meso-structural information in the signal. Furthermore, we validate the potential of joint radial-spherical as compared to single-shell representations. As such, SHARD is optimally suited for applications that require low-rank signal predictions, such as motion correction and outlier rejection. Finally, we illustrate its application for the latter using outlier robust regression.
关键词： Diffusion-weighted imaging,Blind source separation,Multi-shell HARDI,Dimensionality reduction
更新于2025-09-23 15:23:52
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Raman spectroscopy combined with advanced chemometric methods: A new approach for detergent deformulation
摘要： Deformulation of a commercial surfactant mixture using RAMAN spectroscopy and advanced chemometric tools have been investigated. Since the use of surfactants is drastically expanding, their fine identification and quantification are required for quality control and regulation. Dilution of the detergent mixtures combined with RAMAN spectroscopy for signal extraction tools allowed the extraction of the first information concerning the composition of the mixture. The raw materials identified were thus used in an experimental design to obtain a robust model for the determination of detergent composition. The combination of chemometric tools (Independent Component Analysis and Partial Least Square) and spectroscopic methods provided pertinent information for detergent composition. This methodology can easily be transposed to the industrial world.
关键词： detergents deformulation,RAMAN spectroscopy,surfactants characterization,design of experiments,Chemometrics,blind source separation methods
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Wide-aperture deformable mirrors for wavefront distortions compensation in high-power laser complexes
摘要： This paper addresses the determined blind source separation problem and proposes a new effective method unifying independent vector analysis (IVA) and nonnegative matrix factorization (NMF). IVA is a state-of-the-art technique that utilizes the statistical independence between sources in a mixture signal, and an efficient optimization scheme has been proposed for IVA. However, since the source model in IVA is based on a spherical multivariate distribution, IVA cannot utilize specific spectral structures such as the harmonic structures of pitched instrumental sounds. To solve this problem, we introduce NMF decomposition as the source model in IVA to capture the spectral structures. The formulation of the proposed method is derived from conventional multichannel NMF (MNMF), which reveals the relationship between MNMF and IVA. The proposed method can be optimized by the update rules of IVA and single-channel NMF. Experimental results show the efficacy of the proposed method compared with IVA and MNMF in terms of separation accuracy and convergence speed.
关键词： determined,independent vector analysis,Blind source separation,nonnegative matrix factorization
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Thin-Barrier Strained Quantum Well Superlattice Solar Cells
摘要： Cancer diagnosis is based on visual examination under a microscope of tissue sections from biopsies. But whereas pathologists rely on tissue stains to identify morphological features, automated tissue recognition using color is fraught with problems that stem from image intensity variations due to variations in tissue preparation, variations in spectral signatures of the stained tissue, spectral overlap and spatial aliasing in acquisition, and noise at image acquisition. We present a blind method for color decomposition of histological images. The method decouples intensity from color information and bases the decomposition only on the tissue absorption characteristics of each stain. By modeling the charge-coupled device sensor noise, we improve the method accuracy. We extend current linear decomposition methods to include stained tissues where one spectral signature cannot be separated from all combinations of the other tissues’ spectral signatures. We demonstrate both qualitatively and quantitatively that our method results in more accurate decompositions than methods based on non-negative matrix factorization and independent component analysis. The result is one density map for each stained tissue type that classifies portions of pixels into the correct stained tissue allowing accurate identification of morphological features that may be linked to cancer.
关键词： quantification,gastrointestinal tract,prostate,microscopy,image restoration,Blind source separation
更新于2025-09-19 17:13:59
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Heart rate estimation using remote photoplethysmography with multi-objective optimization
摘要： Remote photoplethysmography (rPPG) is being increasingly used to measure heart rate from recorded or live videos. The rhythmic flow of arterial blood, referred to as the blood volume pulse, results in periodic variations in the skin color which are then quantified into a temporal signal for analysis. Independent Component Analysis (ICA) has been used to extract the blood volume pulse which is assumed to have been mixed into the RGB channels of the skin pixels. We propose a novel semi-blind source extraction method for measuring rPPG using a multi-objective optimization approach with autocorrelation as a periodicity measure. Our method was tested on our inhouse video database UBFC-RPPG and the MMSE-HR database [33]. Our in-house database is made publicly available and is specifically aimed towards testing rPPG measurements. Our method showed improved performance over other state of the art rPPG algorithms in terms of accuracy with all the databases.
关键词： Semi-blind source separation,Remote heart rate measurement,Constrained Independent Component Analysis,Multi-objective optimization,Independent Component Analysis,Remote photoplethysmography
更新于2025-09-10 09:29:36
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An anti‐repeater‐jamming approach based on blind source separation for the downlink of satellite communication systems
摘要： In this paper, an anti‐jamming approach is proposed for the downlink of satellite communication systems when encountering a hostile repeater‐jamming. Based on blind source separation, this approach can eliminate repeater‐jamming by separating the mixtures of the communication signals and the repeater‐jamming. Meanwhile, oversampling method is employed to transform the underdetermined mixing of signals into a determined mixing for facilitating the separation. In the simulations, the symbol error ratio (SER) of the separated communication signals can approximate the theory SER, and the anti‐repeater‐jamming capacity can arrive to nearly 28 dB.
关键词： blind source separation,satellite communication,Anti‐jamming,repeater‐jamming,oversampling
更新于2025-09-04 15:30:14