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Gridless methods show great superiority in line spectral estimation. These methods need to solve an atomic $l_0$ norm (i.e., the continuous analog of $l_0$ norm) minimization problem to estimate frequencies and model order. Since this…

Optimization and Control · Mathematics 2024-10-28 Bai Yan , Qi Zhao , Jin Zhang , J. Andrew Zhang , Xin Yao

Phase imaging techniques extract the optical path-length information of a scene, whereas wavefront sensors provide the shape of an optical wavefront. Since these two applications have different technical requirements, they have developed…

Optics · Physics 2018-02-28 F. Soldevila , V. Durán , P. Clemente , J. Lancis , E. Tajahuerce

A low cost scheme to determine the frequency sweep nonlinearity using atomic saturated absorption spectroscopy is demonstrated. The frequency modulation rate is determined by directly measuring the interference fringe number and frequency…

Instrumentation and Detectors · Physics 2017-10-11 Ningfang Song , Xiangxiang Lu , Xiaobin Xu , Xiong Pan , Wei Li , Di Hu , Jixun Liu

Line search (or backtracking) procedures have been widely employed into first-order methods for solving convex optimization problems, especially those with unknown problem parameters (e.g., Lipschitz constant). In this paper, we show that…

Optimization and Control · Mathematics 2024-08-20 Tianjiao Li , Guanghui Lan

Efficient estimation of line spectral from quantized samples is of significant importance in information theory and signal processing, e.g., channel estimation in energy efficient massive MIMO systems and direction of arrival estimation.…

Information Theory · Computer Science 2019-09-04 Jiang Zhu , Qi Zhang , Xiangming Meng

Optimal extraction is a key step in processing the raw images of spectra as registered by two-dimensional detector arrays to a one-dimensional format. Previously reported algorithms reconstruct models for a mean one-dimensional spatial…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 M. Zechmeister , G. Anglada-Escudé , A. Reiners

In this letter, we propose a modulation classification algorithm which is based on the received signal's amplitude for coherent optical receivers. The proposed algorithm classifies the modulation format from several possible candidates by…

Signal Processing · Electrical Eng. & Systems 2018-01-08 Xiang Lin , Yahia A. Eldemerdash , Octavia A. Dobre , Shu Zhang , Cheng Li

Lensless imaging is a popular research field for the advantages of small size, wide field-of-view and low aberration in recent years. However, some traditional lensless imaging methods suffer from slow convergence, mechanical errors and…

This paper proposes two practical implementations of Four-Dimensional Variational (4D-Var) Ensemble Kalman Filter (4D-EnKF) methods for non-linear data assimilation. Our formulations' main idea is to avoid the intrinsic need for adjoint…

Applications · Statistics 2023-05-05 Elias Nin-Ruiz , Jairo Diaz-Rodriguez

In this paper different types of ECG automatic delineation approaches were overviewed. A combination of these approaches was used to create sampling rate independent filtration algorithm for automatic ECG delineation that is capable of…

Medical Physics · Physics 2016-11-28 Hryhorii Chereda , Sergii Nikolaiev , Yury Tymoshenko

Computer model calibration is a crucial step in building a reliable computer model. In the face of massive physical observations, a fast estimation for the calibration parameters is urgently needed. To alleviate the computational burden, we…

Statistics Theory · Mathematics 2022-11-24 Shurui Lv , Yan Wang , Jun Yu

We present a fully parameter-free density-functional approach for the accurate description of optical absorption spectra of insulators, semiconductors and metals. We show that this can be achieved within time-dependent…

Materials Science · Physics 2015-10-28 J. A. Berger

In 3D single particle imaging with X-ray free-electron lasers, particle orientation is not recorded during measurement but is instead recovered as a necessary step in the reconstruction of a 3D image from the diffraction data. Here we use…

Data Analysis, Statistics and Probability · Physics 2016-05-25 Julien Flamant , Nicolas Le Bihan , Andrew V. Martin , Jonathan H. Manton

Lensless in-line holography is a simple, portable, and cost-effective method of imaging especially for the biomedical microscopy applications. We propose a multiplicative gradient descent optimization based method to obtain multi-depth…

Image and Video Processing · Electrical Eng. & Systems 2020-04-20 Sanjeev Kumar , Manjunatha Mahadevappa , Pranab Kumar Dutta

Optical two-dimensional (2D) coherent spectroscopy excels in studying coupling and dynamics in complex systems. The dynamical information can be learned from lineshape analysis to extract the corresponding linewidth. However, it is usually…

Optics · Physics 2020-06-24 Srikanth Namuduri , Michael Titze , Shekhar Bhansali , Hebin Li

We introduce an absorption imaging technique for ultracold gases that suppresses interference fringes and coherence-induced artifacts by reducing the transverse spatial coherence of the imaging light. The method preserves the narrow…

Quantum Gases · Physics 2026-02-16 Julia Fekete , Poppy Joshi , Peter Krüger , Fedja Oručević

The Voigt profile - a convolution of a Gaussian and a Lorentzian - accurately describes the absorption lines of atomic and molecular gases at low probe powers. Fitting such to experimental spectra yields both the Lorentzian natural…

Atomic Physics · Physics 2015-06-04 Thomas M. Stace , Gar-Wing Truong , James Anstie , Eric F. May , Andre N. Luiten

We propose and discuss a numerical method to model electromagnetic emission from the oscillating relativistic charged particles and its coherent amplification. The developed technique is well suited for free electron laser simulations, but…

Computational Physics · Physics 2015-06-19 Igor A. Andriyash , Remi Lehe , Victor Malka

We present ROBOSPECT, a new code to automatically measure and deblend line equivalent widths for both absorption and emission spectra. We test the accuracy of these measurements against simulated spectra as well as manual equivalent width…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Christopher Z. Waters , Julie K. Hollek

The rich information content of measurements in the molecular frame rather than the laboratory frame has motivated the development of several methods for aligning gas phase molecules in space. Even so, for asymmetric tops the problem of…

Atomic Physics · Physics 2016-11-23 Varun Makhija , Xiaoming Ren , Drue Gockel , Anh-Thu Le , Vinod Kumarappan