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A general phase retrieval algorithm based on ptychographicaliterative engine for coherent diffractive imaging 下载免费PDF全文
Coherent diffractive imaging (CDI) is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine (PIE) is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm (gPIE) is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality. 相似文献
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A general phase retrieval algorithm based on a ptychographical iterative engine for coherent diffractive imaging 下载免费PDF全文
Coherent diffractive imaging (CDI) is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine (PIE) is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm (gPIE) is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality. 相似文献
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Quantum optimization algorithms can outperform their classical counterpart and are key in modern technology. The second-order optimization algorithm(the Newton algorithm) is a critical optimization method, speeding up the convergence by employing the second-order derivative of loss functions in addition to their first derivative. Here, we propose a new quantum second-order optimization algorithm for general polynomials with a computational complexity of O(poly(log d)). We use this algorithm to solve the nonlinear equation and learning parameter problems in factorization machines. Numerical simulations show that our new algorithm is faster than its classical counterpart and the first-order quantum gradient descent algorithm. While existing quantum Newton optimization algorithms apply only to homogeneous polynomials, our new algorithm can be used in the case of general polynomials, which are more widely present in real applications. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2021,(10)
正The gradient-based method plays a central role in optimization problems, and is widely applied in engineering control, financial analysis, weather forecast, and training of machine learning models. 相似文献
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A parallel implementation of the electromagnetic dual-primal finite element tearing and interconnecting algorithm (FETI-DPEM) is designed for general three-dimensional (3D) electromagnetic large-scale simulations. As a domain decomposition implementation of the finite element method, the FETI-DPEM algorithm provides fully decoupled subdomain problems and an excellent numerical scalability, and thus is well suited for parallel computation. The parallel implementation of the FETI-DPEM algorithm on a distributed-memory system using the message passing interface (MPI) is discussed in detail along with a few practical guidelines obtained from numerical experiments. Numerical examples are provided to demonstrate the efficiency of the parallel implementation. 相似文献
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B. Andersson G. Gustafson B. Söderberg 《Zeitschrift fur Physik C Particles and Fields》1983,20(4):317-329
We present a general condition on quark fragmentation which gives a hadron distribution satisfying Lorentz invariance and causality. The hadronization can be described as an iterative cascade process, symmetric with respect to iteration from the quark and the antiquark ends. The possible particle distributions are strongly restricted, with few free parameters related to the total multiplicity and corelations in rapidity. These parameters can be given an appealing interpretation in terms of the expected area and perimeter dependence of Wilson loop integrals. 相似文献
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M. Toller 《International Journal of Theoretical Physics》1975,12(6):349-381
We discuss from an operational point of view some fundamental concepts of the micro-scopic physical theories, with the aim of providing a background for a successive investigation of the microscopic space-time structure. We consistently develop the remark that a frame of reference is determined by physical objects which may interact with the objects under investigation. As it is not clear that a state can be prepared by means of physical operations, we do not use the concept of physical state for the foundation of the theory. In our approach, the primitive concepts are the measurement procedures, following which one gets a numerical result, and the transformation procedures, which have the aim of building a frame of reference. We discuss several rules which allow us to define new procedures in terms of known procedures. The statistical laws of physics are formulated in terms of an order relation between measurement procedures, which defines also an equivalence relation. The equivalence classes of measurement procedures are called measurements. We define also equivalence classes of transformation procedures, called transformations. The mathematical structure of the set of measurements and of the set of transformations is discussed in detail. We consider measurements with an arbitrary finite number of possible results, as this enables us to give a rigorous definition of compatibility. Finally, we point out that all the physical theories necessarily contain ideal measurements and transformations which do not correspond to any known physical procedure. The introduction of these ideal objects permits a considerable simplification of the mathematical structure of the theory, but reduces its physical content. 相似文献
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Hua-Gen Yu 《Journal of Molecular Spectroscopy》2009,256(2):287-298
An exact variational algorithm is presented for calculating vibrational energy levels of pentaatomic molecules without any dynamical approximation. The quantum mechanical Hamiltonian of the system is expressed in a set of orthogonal coordinates defined by four scattering vectors in the body-fixed frame. The eigenvalue problem is solved using a two-layer Lanczos iterative diagonalization method in a mixed grid/basis set. A direct product potential-optimized discrete variable representation (PO-DVR) basis is used for the radial coordinates while a non-direct product finite basis representation (FBR) is employed for the angular variables. The two-layer Lanczos method requires only the actions of the Hamiltonian operator on the Lanczos vectors, where the potential-vector products are accomplished via a pseudo-spectral transform technique. By using Jacobi, Radau and orthogonal satellite vectors, we have proposed 21 types of orthogonal coordinate systems so that the algorithm is capable of describing most five-atom systems with small and/or large amplitude vibrational motions. Finally, an universal program (PetroVib) has been developed. Its applications to the molecules , and the van der Waals cluster He3Cl2 are also discussed. 相似文献
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John F. Dowling 《Applied Acoustics》2004,65(3):211-227
Transfer matrix analysis provides a very efficient means to analyse the linear plane-wave acoustic performance of silencer systems in the frequency domain. However, the nature of the algorithm for combination and reduction of the matrices is different for different combinations of elements. This paper describes an efficient algorithm for acoustic analysis of any general silencer system. The basic format of the algorithm is the identification of sub-systems of two-port acoustic elements. Computational time is also reduced by recording the order in which all of the elements are analysed and the sub-systems are reduced. Examples of the analysis of several complex silencer systems are presented. The gain in efficiency over a general global matrix approach is exceptional. 相似文献
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Since wireless in terms of energy-restricted processes, dispersion radii, processing power limitations, buffers, bandwidth-limited connections, active network topologies, and network stream of traffic outlines, sensor networks provide difficult design issues. The number of hops and latency are decreased if there is a relay mote because it interacts directly with relay motes that are closer to the destination mote. The tremendous intensive research in the area of Wireless Sensor Networks (WSN) has gained a lot of significance among the technical community and research. The job of WSN is to sense the data using sensor motes, pass on the data to the destination detection mote which is associated with a processing center and can be used in multiple spans of Internet of Things (IoT) applications. Wireless sensor network has a set of sensor motes. By making use of sensor mote placement strategy all the sensor motes are spread in an area with each mote having its own exceptional location. Internet of things applications are delay sensitive those applications have a challenge of forming the complete path at a lower delay constraint. The proposal is to modify the game theory energy balancing algorithm by making use of relay motes so that overall network lifetime is increased. It has been proved that modified GTEB is better with respect to existing algorithms in terms of delay, figure of hops, energy depletion, figure of alive motes, figure of dead motes, lifespan ratio, routing overhead and throughput. 相似文献
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We describe a simple clinical tracing technique for making reliable test-retest comparisons of laryngeal stroboscopic images. Six young adults with normal larynges served as subjects. Results show the technique to be useful in estimating repeated examination changes. The technique is safe, quick, simple to perform, and inexpensive. 相似文献
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I.IntroductionInbeamformingforsonaritisthemostinterestingfunctionthatonecanobtainthctimcwaveformoutputsofthedesiredsignaltobedetectcdwithanimprovcdSignal-to-NoiseplusInterferenceRatio(SNIR).ItiswellknownthatMVDRbeamforminghasoptimumcapabi1i-hesofsignalprotection,interferenccremovalandnoisercduction.NootherbeamformingtochniquecanyicldalargerincreascinSNIR.Itspoweroutputcanbeusedasawavenumberspectrum(bearing)estimation,whoseprecisionorreso1utionisdeterminedprimarilybySignal-to-NoiseRatio… 相似文献
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Purpose
To present a dual-bolus technique for quantitative dynamic contrast-enhanced MRI (DCE-MRI) and show that it can give an arterial input function (AIF) measurement equivalent to that from a single-bolus protocol.Methods
Five rabbits were imaged using a dual-bolus technique applicable for high-resolution DCE-MRI, incorporating a time resolved imaging of contrast kinetics (TRICKS) sequence for rapid temporal sampling. AIFs were measured from both the low-dose prebolus and the high-dose main bolus in the abdominal aorta. In one animal, TRICKS and fast spoiled gradient echo (FSPGR) acquisitions were compared.Results
The scaled prebolus AIF was shown to match the main bolus AIF, with 95% confidence intervals overlapping for fits of gamma-variate functions to the first pass and linear fits to the washout phase, with the exception of one case. The AIFs measured using TRICKS and FSPGR were shown to be equivalent in one animal.Conclusion
The proposed technique can capture even the rapid circulation kinetics in the rabbit aorta, and the scaled prebolus AIF is equivalent to the AIF from a high-dose injection. This allows separate measurements of the AIF and tissue uptake curves, meaning that each curve can then be acquired using a protocol tailored to its specific requirements. 相似文献19.
We inv estigate the problem in which a volume hologram is produced by two waves of arbitrary amplitude and phase distribution (the only restriction being that they must obey the rules of geometrical optics), and the developed hologram is illuminated by one of the waves having the same phase distribution but not necessarily the same amplitude distribution. Coupled partial differential equations are derived and solved in the form of an infinite series valid for both transmission and reflection holograms. For transmission holograms a simple approximate solution is given for the amplitude of the reconstructed wave in the immediate vicinity of the input surface. 相似文献
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A quadratic spinor Lagrangian for general relativity 总被引:1,自引:0,他引:1
We present a newfinite action for Einstein gravity in which the Lagrangian is quadratic in the covariant derivative of a spinor field. Via a new spinor-curvature identity, it is related to the standard Einstein-Hilbert Lagrangian by a total differential term. The corresponding Hamiltonian, like the one associated with the Witten positive energy proof, is fully 4-covariant. It defines quasi-local energy-momentum and can be reduced to the one in our recent positive energy proof.This essay received the fourth award from the Gravity Research Foundation, 1994—Ed. 相似文献