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Semi-analytical non-iterative cross-correlation frequency-resolved optical gating retrieving algorithm

OPTICS COMMUNICATIONS 2025年 574卷

作者： Jarutis, Vygandas Stravinskaite, Auguste Kuliesaite, Migle Vengelis, Julius Vilnius Univ Laser Res Ctr Sauletekio Ave 10 LT-10223 Vilnius Lithuania

In this article we present a semi-analytical non-iterative algorithm for reconstruction of complex pulse amplitude from cross-correlational frequency resolved optical gating (XFROG) measurement when Gaussian shape pulse is used as reference pulse. The method is tested both with digitally generated data and experimentally measured XFROG traces and allowed to estimate retrieving uncertainty.

关键词： XFROG non-iterative algorithm Pulse characterization

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Boundary geometry reconstruction for orthotropic heat conduction problems based on HT-FEM

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NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS 2025年第1期86卷 87-105页

作者： Qiu, Wenkai Chen, Haolong Zhou, Huanlin Hefei Univ Technol Sch Civil Engn Hefei Peoples R China

It is usually inconvenient to directly measure the inner boundary geometry shape of thermal pipeline and furnace wall in engineering. A non-iterative algorithm is proposed to reconstruct the geometry shape of these structures for orthotropic heat conduction problems in nondestructive evaluation. First, the temperature of measurement points in the real domain is determined by utilizing the hybrid Trefftz finite element method (HT-FEM). Then, a virtual inner boundary is introduced into forming a virtual domain. The deviation between the measured temperature and the estimated temperature is defined as an objective function. The temperature on the virtual boundary is obtained by calculating the minimum of the objective function. Finally, the virtual boundary temperature is substituted into the direct problem to acquire the temperature distribution in the global domain. And the inner boundary geometry shape is identified by searching the isothermal curve. Several numerical examples are provided to verify the stability and effectiveness of the proposed method. The merit of this algorithm is that the unknown geometry shape can be directly and accurately reconstructed without the complex iterative process.

关键词： Geometry reconstruction HT-FEM inverse problem non-iterative algorithm orthotropic heat conduction

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ISAR imaging with random missing observations based on non-iterative signal reconstruction algorithm 12

ISAR imaging with random missing observations based on non-i...

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12th IEEE International Conference on Signal Processing (ICSP)

作者： Wang, Yong Kang, Jian Zhang, Runbin Harbin Inst Technol Res Inst Elect Engn Technol Harbin 150006 Peoples R China

ISBN: (纸本)9781479921867

Random missing observations in real-world inverse synthetic aperture radar (TSAR) imaging may appear due to the instability of the radar system. Under this circumstance, the signal of one range bin over the slow-time has limited samples. Using traditional range-Doppler algorithm, high-quality TSAR images for random missing observations cannot be obtained. Recently, a new non-iterative algorithm based on the combined robust statistics and compressive sensing (CS) theory has been proposed to efficiently recover a complete signal from a small random set of samples, showing robustness in the presence of noise [16]. It is also important to emphasize that non-iterative method is computationally simpler than the iterative signal reconstruction solutions, and thus more amenable to practical applications. Therefore, based on the non-iterative robust signal reconstruction method, a new algorithm for TSAR imaging with random missing observations is proposed in this paper. The efficiency of the proposed approach is demonstrated on the examples with simulated and real data.

关键词： Compressive sensing non-iterative algorithm Signal reconstruction Random observations ISAR imaging

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Extended framework of Hamilton's principle for continuum dynamics

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INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2013年第20-21期50卷 3418-3429页

作者： Kim, Jinkyu Dargush, Gary F. Ju, Young-Kyu Korea Univ Sch Civil Environm & Architectural Engn Seongbuk Goo 136713 South Korea SUNY Buffalo Dept Mech & Aerosp Engn Buffalo NY 14260 USA

Hamilton's principle is the variational principle for dynamical systems, and it has been widely used in mathematical physics and engineering. However, it has a critical weakness, termed end-point constraints, which means that in the weak form, we cannot use the given initial conditions properly. By utilizing a mixed formulation and sequentially assigning initial conditions, this paper presents a novel extended framework of Hamilton's principle for continuum dynamics, to resolve such weakness. The primary applications lie in an elastic and a J(2)-viscoplastic continuum dynamics. The framework is simple, and initiates the development of a space-time finite element method with the proper use of initial conditions. non-iterative numerical algorithms for both elasticity and J(2)-viscoplasticity are presented. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Hamilton's principle Initial conditions Mixed formulation Continua dynamics Space-time finite element non-iterative algorithm

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On computation of the three-dimensional flow past a stretching sheet

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APPLIED MATHEMATICS AND COMPUTATION 2007年第2期188卷 1244-1250页

作者： Ariel, P. Donald Trinity Western Univ Dept Math Sci Langley BC V2Y 1Y1 Canada

A non-iterative numerical scheme is presented which computes the steady, three-dimensional flow of a viscous, incompressible fluid past a stretching sheet in a single integration. It also eliminates the possible error caused by taking the value of numerical infinity (representing the unbounded domain of the flow) as a finite number. The solutions are developed in terms of a parameter K in the interval [0, 1], from which the appropriate flow parameters can be readily obtained. The scheme makes implicit use of infinite series of exponentials for velocity components along the sheet. The issue of convergence of these series is also discussed. (c) 2006 Elsevier Inc. All rights reserved.

关键词： stretching sheet non-iterative algorithm series of exponentials Ackroyd's method Samuel and Hall's scheme

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Localization of molecular orbitals on fragments

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JOURNAL OF COMPUTATIONAL CHEMISTRY 2012年第17期33卷 1495-1510页

作者： Sax, Alexander F. Graz Univ Dept Chem Graz Austria

A non-iterative algorithm for the localization of molecular orbitals (MOs) from complete active space self consistent field (CASSCF) and for single-determinantal wave functions on predefined moieties is given. The localized fragment orbitals can be used to analyze chemical reactions between fragments and also the binding of fragments in the product molecule with a fragments-in-molecules approach by using a valence bond expansion of the CASSCF wave function. The algorithm is an example of the orthogonal Procrustes problem, which is a matrix optimization problem using the singular value decomposition. It is based on the similarity of the set of MOs for the moieties to the localized MOs of the molecule;the similarity is expressed by overlap matrices between the original fragment MOs and the localized MOs. For CASSCF wave functions, localization is done independently in the space of occupied orbitals and active orbitals, whereas, the space of virtual orbitals is mostly uninteresting. Localization of HartreeFock or KohnSham density functional theory orbitals is not straightforward;rather, it needs careful consideration, because in this case some virtual orbitals are needed but the space of virtual orbitals depends on the basis sets used and causes considerable problems due to the diffuse character of most virtual orbitals. (c) 2012 Wiley Periodicals, Inc.

关键词： localized fragment orbitals non-iterative algorithm orthogonal Procrustes problem

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Extended framework of Hamilton's principle applied to Duffing oscillation

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APPLIED MATHEMATICS AND COMPUTATION 2020年 367卷 124762-000页

作者： Kim, Jinkyu Lee, Hyeonseok Shin, Jinwon Hanyang Univ Sch Architecture & Architectural Engn 55 Hanyangdaehak Ro Seoul 15588 Kyeonggi Do South Korea Korea Construct Safety Engn 17 SuYeong Ro1079-3 GwangAn Dong665Beon Gil Busan 48243 South Korea Catholic Kwandong Univ Dept Architectural Engn 24 Beomil Ro579Beon Gil Gangneung Si 25601 Gangwon Do South Korea

The paper begins with a novel variational formulation of Duffing equation using the extended framework of Hamilton's principle (EHP). Unlike the original Hamilton's principle, this formulation properly accounts for initial conditions, and it recovers all the governing differential equations as its Euler-Lagrange equation. Thus, it serves base for the development of novel computational methods, involving finite element representation over time. For its feasibility, we provide the simplest temporal finite element method by adopting linear temporal shape functions. Numerical examples are included to verify and investigate performance of non-iterative algorithm in the developed method. (C) 2019 Published by Elsevier Inc.

关键词： Duffing equation Extended framework of Hamilton's principle Variational formulation Temporal finite element method non-iterative algorithm

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Low complexity subcarrier and power allocation for utility maximization in uplink OFDMA systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第5期7卷 1667-1675页

作者： Ng, Cho Yiu Sung, Chi Wan Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China

We consider the joint subcarrier and power allocation problem with the objective of maximizing the total utility of users in the uplink of an OFDMA system. Our formulation includes the problems of sum rate maximization, proportional fairness and max-min fairness as special cases. Unlike some previous algorithms, which,are iterative and time consuming, our proposed one is non-iterative and with time complexity of only O(KN log(2) N), where K and N are the number of users and subcarriers respectively. We prove that it provides a solution that is Pareto optimal within a large neighborhood of itself. Besides, we derive an efficiently computable upper bound of the optimal solution. Simulation results show that our algorithm is nearly optimal.

关键词： non-iterative algorithm local Pareto optimal upper bound subcarrier and power allocation utility maximization fairness uplink OFDMA

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Extended framework of Hamilton's principle for single-degree-of-freedom nonlinear damping systems

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JOURNAL OF LOW FREQUENCY NOISE VIBRATION AND ACTIVE CONTROL 2021年第3期40卷 1437-1452页

作者： Kim, Jinkyu Hanyang Univ Sch Architecture & Architectural Engn 55 Hanyangdaehak Ro Sangnok 15588 Kyeonggi South Korea

The paper explores application of the variational formalism called extended framework of Hamilton's principle to nonlinear damping systems. Single-degree-of-freedom systems with dominant source of nonlinearity from polynomial powers of the velocity are initially considered. Appropriate variational formulation is provided, and then the corresponding weak form is discretized to produce a novel computational method. The resulting low-order temporal finite element method utilizes non-iterative algorithm, and some examples are provided to verify its performance. The present temporal finite element method using small time step is equivalent to the adaptive Runge-Kutta-Fehlberg method with default error tolerances in MATLAB, and additional simulation shows its good convergence characteristics.

关键词： Extended framework of Hamilton's principle nonlinear damping system non-iterative algorithm variational formalism temporal finite element method

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Generalized Multiplexed Waveform Design Framework for Cost-Optimized MIMO Radar

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2021年 69卷 88-102页

作者： Hammes, Christian Shankar, Bhavani M. R. Ottersten, Bjorn Univ Luxembourg Interdisciplinary Ctr Secur Reliabil & Trust L-1855 Luxembourg Luxembourg

Cost-optimization through the minimization of hardware and processing costs with minimal loss in performance is an interesting design paradigm in evolving and emerging Multiple-Input-Multiple-Output (MIMO) radar systems. This optimization is a challenging task due to the increasing Radio Frequency (RF) hardware complexity as well as the signal design algorithm complexity in applications requiring high angular resolution. Towards addressing these, the paper proposes a low-complexity signal design framework, which incorporates a generalized time multiplex scheme for reducing the RF hardware complexity with a subsequent discrete phase modulation. The scheme further aims at achieving simultaneous transmit beamforming and maximum virtual MIMO aperture to enable better target detection and discrimination performance. Furthermore, the paper proposes a low-complexity signal design scheme for beampattern matching in the aforementioned setting. The conducted performance evaluation indicates that the listed design objectives are met.

关键词： Radio frequency Modulation MIMO communication Multiplexing Optimization Complexity theory Array signal processing Angle-Doppler coupling suppression block-circulant decomposition MIMO radar multiplexing non-iterative algorithm transmit beamforming virtual MIMO convex optimization finite alphabets multiple phase shift keying

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