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Full cycle rapid scan EPR deconvolution algorithm

JOURNAL OF MAGNETIC RESONANCE 2017年 281卷 272-278页

作者： Tseytlin, Mark West Virginia Univ Sch Med Dept Biochem Morgantown WV 26506 USA West Virginia Univ Robert C Byrd Hlth Sci Ctr In Vivo Multifunct Magnet Resonance Ctr Morgantown WV 26506 USA

Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment;the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit;the transient spin system response must decay within the scan period.

关键词： Rapid scan EPR EPR imaging deconvolution algorithm Ill-posed problem Linear systems

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An improved deconvolution algorithm using B-splines for well-test data analysis in petroleum engineering

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JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING 2017年 149卷 306-314页

作者： Liu, Wenchao Liu, Yuewu Han, Guofeng Zhang, Jianye Wan, Yizhao Chinese Acad Sci Inst Mech Beijing 100190 Peoples R China Petro China Tarim Oilfield Co Res Inst Explorat & Dev Korla 841000 Xinjiang Peoples R China

Ilk et al.'s deconvolution algorithm using B-splines involves the Laplace transformation of the convolution equation with respect to production rate and wellbore pressure based on Duhamel principle. However, for common cases, the production rate function has "discontinuity" with respect to production time;it does not satisfy the precondition that the function to be transformed by Laplace transformation should be continuous. This inherent defect may directly cause enormous amount of computational time or even the failure of the numerical Laplace inversion in the deconvolution process. Based on these concerns, a fundamentally improved deconvolution algorithm using B-splines is presented here. In the convolution equation, the wellbore pressure derivative corresponding to constant unit production rate as the target of deconvolution is still represented by weighted summation of second-order B-splines;however, the computation process of the deconvolution is kept in the level of integral in the real time space instead of the Laplace space, for the reason that there will be no continuity requirement for the production rate function in the application of Duhamel principle for the deconvolution computation problem. According to the real production rate history, a technique of piecewise analytical integration is adopted for obtaining the elements of sensitivity matrix of a linear system with respect to weight coefficients;the linear system is generated by substituting the measured wellbore pressure data and corresponding variable 'production rate data into the convolution equation containing B-splines. The proposed direct analytical solution method of the integration for calculating the elements of the sensitivity matrix can not only guarantee the success of the deconvolution computation, but also can largely enhance the deconvolution computation speed. Moreover, in order to further improve the computation speed, a binary search method is also applied to find which production

关键词： deconvolution algorithm Well testing Duhamel principle Least square method

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A robust, fast, and accurate deconvolution algorithm for EM-Field measurements around GSM and UMTS base stations with a spectrum analyzer

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2002年第6期51卷 1163-1169页

作者： Joseph, W Olivier, C Martens, L State Univ Ghent Dept Informat Technol B-9000 Ghent Belgium

In this paper, we present a new robust, fast, and accurate deconvolution algorithm for correcting noise disturbed measurements and eliminating the influence of the resolution filter of a spectrum analyzer used for EM-field measurements around a GSM and UNITS base station. Our purpose is to be able to determine immediately the field values at a measurement site. Therefore the algorithm has to be fast and accurate. Furthermore, because of the presence of noise, our algorithm has to be robust. Our algorithm that uses windowing and filtering meets those demands and reduces the present noise by an additional convolution with a square wave function.

关键词： deconvolution algorithm electromagnetic measurements GSM-UMTS resolution filter spectrum analyzer

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Finding the optimal deconvolution algorithm for MR perfusion in carotid stenosis: Correlations with angiographic cerebral circulation time

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JOURNAL OF NEURORADIOLOGY 2016年第4期43卷 290-296页

作者： Lin, Chung-Jung Hung, Sheng-Che Chang, Feng-Chi Guo, Wan-Yuo Luo, Chao-Bao Kowarschik, Markus Chu, Wei-Fa Liou, Adrian J. Y. Kang Taipei Vet Gen Hosp Dept Radiol 201Shipai RdSect 2 Taipei 11217 Taiwan Natl Yang Ming Univ Sch Med Taipei Taiwan Siemens AG Healthcare Sect Angiog & Intervent Xray Syst Forchheim Germany

Purpose: The aim of our study is to explore the impacts of different deconvolution algorithms on correlations between CBF, MTT, CBV, TTP, Tmax from MR perfusion (MRP) and angiography cerebral circulation time (CCT). Methods: Retrospectively, 30 patients with unilateral carotid stenosis, and available prestenting MRP and angiography were included for analysis. All MRPs were conducted in a 1.5-T MR scanner. Standard singular value decomposition, block-circulant, and two delay-corrected algorithms were used as the deconvolution methods. All angiographies were obtained in the same bi-plane flat-detector angiographic machine. A contrast bolus of 12 mL was administrated via angiocatheter at a rate of 8 mL/s. The acquisition protocols were the same for all cases. CCT was defined as the difference between time to peak from the cavernous ICA and the parietal vein in lateral view. Pearson correlations were calculated for CCT and CBF, MTT, CBV, TTP, Tmax. Results: The correlation between CCT and MTT was highest with Tmax (r= 0.65), followed by MTT (r= 0.60), CBF (r=-0.57), and TTP (r=0.33) when standard singular value decomposition was used. No correlation with CBV was noted. Conclusions: MRP using a singular value decomposition algorithm confirmed the feasibility of quantifying cerebral blood flow deficit in steno-occlusive disease within the angio-room. This approach might further improve patient safety by providing immediate cerebral hemodynamics without extraradiation and iodine contrast. (C) 2016 Elsevier Masson SAS. All rights reserved.

关键词： Carotid stenosis Cerebral blood flow Cerebral circulation time deconvolution algorithm Quantitative DSA MR perfusion Time density curve

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An Optimal Subspace deconvolution algorithm for Robust and High-Resolution Beamforming

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SENSORS 2022年第6期22卷 2327-2327页

作者： Su, Xiruo Miao, Qiuyan Sun, Xinglin Ren, Haoran Ye, Lingyun Song, Kaichen Zhejiang Univ Coll Biomed Engn & Instrument Sci Hangzhou 310058 Peoples R China Zhejiang Univ Sch Earth Sci Hangzhou 310058 Peoples R China Zhejiang Univ Sch Aeronaut & Astronaut Hangzhou 310058 Peoples R China

Utilizing the difference in phase and power spectrum between signals and noise, the estimation of direction of arrival (DOA) can be transferred to a spatial sample classification problem. The power ratio, namely signal-to-noise ratio (SNR), is highly required in most high-resolution beamforming methods so that high resolution and robustness are incompatible in a noisy background. Therefore, this paper proposes a Subspaces deconvolution Vector (SDV) beamforming method to improve the robustness of a high-resolution DOA estimation. In a noisy environment, to handle the difficulty in separating signals from noise, we intend to initial beamforming value presets by incoherent eigenvalue in the frequency domain. The high resolution in the frequency domain guarantees the stability of the beamforming. By combining the robustness of conventional beamforming, the proposed method makes use of the subspace deconvolution vector to build a high-resolution beamforming process. The SDV method is aimed to obtain unitary frequency matrixes more stably and improve the accuracy of signal subspaces. The results of simulations and experiments show that when the input SNR is less than -27 dB, signals of decomposition differ unremarkably in the subspace while the SDV method can still obtain clear angles. In a marine background, this method works well in separating the noise and recruiting the characteristics of the signal into the DOA for subsequent processing.

关键词： Direction of Arrival Estimation (DOA) subspace vector deconvolution algorithm

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Frequency Diverse Array and Spotlight Synthetic Aperture Radar 2D Imaging Based on Multiple Repeated Subpulses

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SENSORS 2025年第4期25卷 1075-1075页

作者： Li, Qinlin Liao, Kefei Xie, Ningbo Chen, Hanbo Guilin Univ Elect Technol Sch Informat & Commun Guilin 541004 Peoples R China Guangxi Intelligent Electromagnet Spectrum Percept Guilin 541004 Peoples R China

Frequency diverse array (FDA) beams show an "S" shape in space and cannot form a spot beam;thus, they cannot be directly combined with spotlight synthetic aperture radar (SSAR). In this paper, we propose a 2D imaging system emitting multiple repeated subpulses using an FDA and spotlight synthetic aperture radar (MRS-FDA-SSAR). This system carries the FDA on an airborne platform and uses the frequency difference between the array elements to synthesize broadband signals and obtain the distance-direction resolution, and then it uses a synthetic aperture technique to obtain the azimuth-direction resolution. Subsequently, 2D imaging results are obtained using the BP algorithm. A deconvolution algorithm is introduced to address the problem of high target sidelobes in the BP imaging results, which can result in the masking of weak targets. This allows 2D imaging results to be obtained with lower sidelobes. Finally, the MRS-FDA-SSAR model was simulated in experiments to verify its effectiveness.

关键词： frequency diverse array higher energy accumulation BP algorithm spotlight synthetic aperture radar deconvolution algorithm

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Influence of light spatial coherence on speckle imaging through scattering layers

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OPTICAL ENGINEERING 2025年第2期64卷

作者： Zhou, Yuanyuan Zhu, Dabo Soochow Univ Appl Technol Coll Suzhou Peoples R China

This work investigates the influence of light coherence on speckle imaging through a scattering layer. A focused laser is incident on a rotating ground glass (RGG). By changing the distance from the focus to the RGG, the degree of coherence of partially spatially coherent light can be controlled. Speckle correlation technique with iterative phase-retrieval algorithm and deconvolution method using point spread function are employed, and their results indicate that the lower the spatial coherence of the light, the higher the quality of the reconstructed object. Moreover, similar conclusions are obtained using an LED as light source. The results suggest that the coherence of light source should be carefully examined and selected to achieve high-quality speckle imaging through scattering layers.

关键词： speckle imaging spatial coherence of light speckle correlation technique deconvolution algorithm rotating ground glass

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Resolving multiple combustion parameters from a single transition using degraded deconvolution of Voigt lineshape

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INFRARED PHYSICS & TECHNOLOGY 2018年 92卷 6-12页

作者： Li, Jinyi Yang, Sen Du, Zhenhui Gao, Hong Wei, Yingying Tianjin Polytech Univ Key Lab Adv Elect Engn & Energy Technol Tianjin 300387 Peoples R China Tianjin Univ State Key Lab Precis Measuring Technol & Instrume Tianjin 300072 Peoples R China

A novel algorithm to fast deconvolve a molecular transition for its Gaussian and Lorentzian broadening was reported, and was further used to simultaneously measure multiple parameters, i.e. species concentration, temperature, and pressure, for combustion diagnostics. The proposed method was demonstrated by theory simulation and laboratory verification with combustion experiment. Direct absorption spectroscopy of H2O transition at 7185.6 cm(-2) in premixed methane/air flames is used to verify the accuracy. The measurement temperature is agreement with that by two-line thermometry and thermocouple. The method is simple and feasible for non-intrusive simultaneous measurements of gas temperature, concentration, and pressure without calibration or other contact sensors. With an appropriately selected spectral line for analysis, the method can be applied to combustion diagnostics and industrial process control applications. (C) 2018 Elsevier B.V. All rights reserved.

关键词： deconvolution algorithm Combustion diagnostics Laser absorption spectroscopy Linewidth

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deconvolution of multiwell test data

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SPE JOURNAL 2007年第4期12卷 420-428页

作者： Levitan, Michael M. BP Amer E&P Technol Grp Houston TX USA

The deconvolution analysis technique that evolved with development of the deconvolution algorithms by von Schroeter et al. (2004), Levitan (2005), and Levitan et al. (2006) became a useful addition to the suite of techniques used in well-test analysis. This deconvolution algorithm, however, is limited to the pressure and rate data that originate from a single active well on the structure. It is ideally suited for analysis of the data from exploration and appraisal well tests. The previously mentioned deconvolution algorithm can not be used with the data that are acquired during startup and early field development that normally involve several producing wells. The paper describes a generalization of deconvolution to multiwell pressure and rate data. Several approaches and ideas for multiwell deconvolution are investigated and evaluated. The paper presents the results of this investigation and demonstrates performance of the deconvolution algorithm on synthetic multiwell test data.

关键词： pressure transient testing deconvolution algorithm deconvolution sequence pressure transient analysis Upstream Oil & Gas model prediction test sequence test data Drillstem Testing

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Towards robust deconvolution of low-dose perfusion CT: Sparse perfusion deconvolution using online dictionary learning

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MEDICAL IMAGE ANALYSIS 2013年第4期17卷 417-428页

作者： Fang, Ruogu Chen, Tsuhan Sanelli, Pina C. Cornell Univ Dept Elect & Comp Engn Ithaca NY 14850 USA Weill Cornell Med Coll Dept Radiol New York NY USA Weill Cornell Med Coll Dept Publ Hlth New York NY USA

Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Computed tomography perfusion Radiation dosage Sparse representation Online dictionary learning deconvolution algorithm

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