- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Evaluation of the quantum time-correlation functions employing the Hamilton–Jacobi dynamics framework
摘要： The quantum Hamilton–Jacobi equation (QHJE) is formally equivalent to the time-dependent Schr?dinger equation, and the solutions to the QHJE can be easily interpreted in terms of trajectories providing a link between classical and quantum mechanics. The trajectory-based approaches to quantum molecular dynamics are, generally, appealing because they circumvent exponential scaling associated with exact quantum methods with the system size, and because, unlike classical molecular dynamics, such methods incorporate dominant quantum effects due to delocalization of wavefunctions describing the nuclei. We explore the utility of the QHJE framework for calculations of the time-correlation functions (TCFs) involving quantum evolution defined by the Boltzmann density operator and by the Hamiltonian time-evolution operator. The implementation is based on solutions to the imaginary-time counterpart to the QHJE, which yield approximations to the ground state wavefunction. The resulting nodeless wavefunction is used to generate a basis in coordinate space, which is efficient for evaluation of the low-lying excited states and of the quantum TCFs, including the Kubo-transformed TCFs, at low temperature. The QHJE/basis approach is illustrated on several model systems in and out of thermal equilibrium, i.e., the H2 dimer and bound anharmonic potentials. If a system exhibits large amplitude motion, e.g., in case of the nonequilibrium dynamics, then the real-time trajectory propagation provides an alternative to the basis representation, as demonstrated on a model describing the inversion mode of the ammonia molecule and ion.
关键词： Trajectory dynamics,Time-correlation functions,Excited states,Quantum dynamics
更新于2025-09-23 15:19:57
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Ghost Spectroscopy with Classical Correlated Amplified Spontaneous Emission Photons Emitted by An Erbium-Doped Fiber Amplifier
摘要： We demonstrate wavelength-wavelength correlations of classical broad-band amplified spontaneous emission (ASE) photons emitted by an erbium-doped fiber amplifier (EDFA) in a wavelength regime around 1530 nm. We then apply these classical correlated photons in the framework of a real-world ghost spectroscopy experiment at a wavelength of 1533 nm to acetylene (C2H2) reproducing the characteristic absorption features of the C-H stretch and rotational bands. This proof-of-principle experiment confirms the generalization of an ASE source concept offering an attractive light source for classical ghost spectroscopy. It is expected that this will enable further disseminating ghost modality schemes by exploiting classical correlated photons towards applications in chemistry, physics and engineering.
关键词： spectral correlations,quantum optics,coherence,correlated photons,erbium-doped fiber amplifier,photon correlation modalities,ghost imaging,amplified spontaneous emission (ASE),spectroscopy,ghost spectroscopy,ghost modalities
更新于2025-09-19 17:15:36
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Robust Visual Tracking Based on Adaptive Extraction and Enhancement of Correlation Filter
摘要： In recent years, correlation filter (CF)-based tracking methods have demonstrated competitive performance. However, conventional CF-based methods suffer from unwanted boundary effects because of the periodic assumption of the training and detection samples. A spatially regularized discriminative CF (SRDCF) has greatly alleviated boundary effects by proposing the spatial regularization weights, which penalize the CF coefficients during learning. However, the SRDCF utilizes a naive decaying exponential model to passively and fixedly update the CF from the previous results. Therefore, if the target meets with occlusion or is out of view, the SRDCF may encounter over-fitting to the recent polluted samples, which may lead to tracking drift and failure. In this paper, we present a novel CF-based tracking method to resolve this issue by dynamically and adaptively correcting the weights of learning CFs and fusing them together to promote a more robust tracking. Thus, if the recent samples are inaccurate in the case of occlusion or are out of view, our method will down-weight the corresponding CFs and vice versa. Moreover, in order to decrease computational complexity and ensure memory efficiency, we extract the key CFs from the previous frames to remove redundant CFs under the contiguous frame indexes constraint. Thus, we do not need to store all CFs and decrease computational burden. Benefiting from the extraction and enhancement of CF, our method improves the tracking precision on OTB-2015, VOT-2016 and UAV123 benchmarks and achieves a 56.0% relative gain in speed compared with the SRDCF. The extensive experimental results demonstrate that our method is competitive with the state-of-the-art algorithms.
关键词： sample learning,adaptive extraction and enhancement,Visual tracking,correlation filter
更新于2025-09-19 17:15:36
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Error estimation of 3D reconstruction in 3D digital image correlation
摘要： Three-dimensional digital image correlation (3D-DIC) is widely used in various measurement fields. Once a DIC setup is established, different parameters, such as lens focal length, pixel size, stereo angle, and working distance, are easy to know or measure; the range of the matching error is generally 0.01–0.02 pixels. It would be very convenient if the measurement error could be estimated based on the parameters above without performing the entire DIC calculation process. In this study, a numerical simulation was conducted to study the variation of the 3D reconstruction error with the stereo angle in different measurement areas. It was found that the error of the center point was closely related to the error of the full field. Therefore, using simple parameters to describe the 3D reconstruction error of the center point is of great significance for estimating the overall error of a DIC system. The general solution of the 3D reconstruction equation was simplified on the premise that high order terms of pixel coordinates could be omitted. The derived error estimation formulas had a simple form and described the 3D reconstruction error of the center point in three directions. Through a set of static experiments, the 3D reconstruction error of a planar object under different stereo angles (from 10° to 120°) was studied. The matching error was calculated by a 2D-DIC software and inserted into the proposed formulas to obtain the estimated error. The estimated error was compared with the results of a 3D-DIC software, and the effectiveness of the proposed method was verified.
关键词： digital image correlation,error estimation,3D reconstruction
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - High Sensitivity Ultrasonic Inspection Technique Using Pulse Compression Method
摘要： We developed an ultrasonic inspection technique using a pulse compression method for detecting bonding defects with interfaces of stacked wafers. This technique can detect the minute echoes reflected from the bonding interfaces by computing the correlation function between transmitted and received signals. We designed a measurement condition for pulse compression with a transmitted signal and took an ultrasonic measurement of a 3-layer stacked sample. We compared the defect detection sensitivity of the pulse compression method with the ultrasonic inspection using pulse waves. The experimental results showed that the noise of an ultrasonic image was reduced and minute defects could be detected by applying developed method.
关键词： multi-layer staked sample,Correlation function,Defect detection,Ultrasonic inspection,Pulse compression
更新于2025-09-19 17:15:36
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Correlation functions with single-photon emitters under noisy resonant continuous excitation
摘要： To characterize the statistics and indistinguishability of a source, it is common to measure the correlation functions of the emitted field using various interferometers. Here, we present a theoretical framework for the computation of the correlation functions of a two-level system that is resonantly driven by a realistic noisy cw excitation laser. Analytic expressions of the first- and second-order autocorrelation functions are obtained where the various contributions of the noisy excitation source are correctly taken into account. We predict that, even in the low power regime, the noise source has a strong influence on the two-level system dynamics, which is not anticipated by simpler models. The characterization of photon indistinguishability in the pulsed excitation regime is usually done by measuring the value of the zero-delay intensity correlation obtained with a Hong-Ou-Mandel interferometer. We show that this figure is irrelevant in the cw excitation regime and we introduce the coalescence time window, a figure of merit based on a probabilistic interpretation of the notion of photon indistinguishability. We finally use the coalescence time window to quantify how noisy cw excitation influences photon indistinguishability.
关键词： Hong-Ou-Mandel interferometer,correlation functions,coalescence time window,noisy resonant continuous excitation,single-photon emitters
更新于2025-09-19 17:15:36
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Brain MR Kurtosis Imaging Study: Contrasting Gray and White Matter
摘要： This paper mainly focuses on characterization of different brain tissues such as White and Gray matter (WM and GM) using the relation between Diffusion Tensor Imaging and Diffusion Kurtosis Imaging parameters. Both Diffusion Tensor Imaging and Diffusion Kurtosis Imaging are the extension of Diffusion Weighted Imaging, which are widely applied for analysing micro fibre structure of human organs non-invasively. Diffusion Tensor Imaging assumes that the water diffusion is in Gaussian nature and Diffusion Kurtosis Imaging accounts the deviation of the Gaussian nature. This study, conducted a correlation and regression analysis between different parametric maps generated from Diffusion Kurtosis Images. For this we have chosen 200 regions of interest pixels drawn from brain MRIs. From the results, it is observed that there is a significant variation in the correlation results between Axial Diffusion and Kurtosis Fractional Anisotropy maps of Gray matter and White matter tissues. This can be employed for enhancing accuracy in MRI segmentation techniques and also as a potential tool for Neuro degenerative disease detection.
关键词： Gray matter,Diffusion Tensor Imaging,White matter,brain MRI,Diffusion Kurtosis Imaging,Correlation analysis,Regression analysis
更新于2025-09-19 17:15:36
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Fast RGB-T Tracking via Cross-Modal Correlation Filters
摘要： This paper studies how to perform RGB-T object tracking in the correlation filter framework. Given the input RGB and thermal videos, we utilize the correlation filter for each modality due to its high performance in both of accuracy and speed. To take the interdependency between RGB and thermal modalities, we introduce the low-rank constraint to learn filters collaboratively, based on the observation that different modality features should have similar filters to make them have consistent localization of the target object. For optimization, we design an efficient ADMM (Alternating Direction Method of Multipliers) algorithm to solve the proposed model. Experimental results on the benchmark datasets (i.e., GTOT, RGBT210 and OSU-CT) suggest that the proposed approach performs favorably in both accuracy and efficiency against the state-of-the-art RGB-T methods.
关键词： RGB-Thermal,Tracking,Correlation Filters,Cross-Modal,Low-Rank
更新于2025-09-19 17:15:36
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Low-frame-rate single camera system for 3D full-field high-frequency vibration measurements
摘要： A single-camera stereo-digital image correlation (stereo-DIC) system to obtain 3D full-field vibration measurements is proposed. The optical setup is composed of two planar mirrors and a single low frame rate camera, thus resulting in a compact and low-cost equipment. The two mirrors are used to create pseudo-stereo images of a target surface on the camera sensor, which are then correlated by using stereo-DIC. The image acquisition process is carried out at low frame rates and the Nyquist-Shannon frequency limitation is overcome by adopting a down-sampling approach under the hypothesis that the vibration signal is characterized by a single known frequency component. The developed pseudo-stereo DIC system allows to obtain 3D full-field vibration measurements in a frequency range up to 4 kHz even with an available frame rate (at full resolution) of 178 fps. The effectiveness of the described approach has been verified by performing vibration measurements on a cantilever plate and a turbine blade.
关键词： Single low-speed camera,Vibration measurement,Down-sampling approach,Digital image correlation
更新于2025-09-19 17:15:36
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Microperimetry for Geographic Atrophy Secondary to Age-Related Macular Degeneration
摘要： Geographic atrophy (GA) is a progressive, advanced form of age-related macular degeneration leading to visual function impairment and irreversible vision loss. Standard clinical tests to evaluate visual function in patients with GA provide poor anatomic-functional correlation, while fundus imaging does not assess the visual function deficit. Microperimetry is a psychophysical visual function test that spatially maps retinal sensitivity and allows for correlation of anatomic features with visual function. In this review, we present an overview of mesopic microperimetry for GA, including: commercially available microperimetry devices, strategies to capture a mesopic microperimetry test, and strategies to assess and interpret microperimetry data in patients with GA. We demonstrate the importance of microperimetry data for assessing GA progression and for evaluating visual function loss through anatomic-functional correlations. Although valuable, current microperimetry tests require an extensive time commitment from patient and examiner, and the development of faster, more reproducible, and accessible methods is important to enable broader use of microperimetry in both clinical and research settings.
关键词： anatomic-functional correlation,visual function,geographic atrophy,microperimetry,age-related macular degeneration,retinal sensitivity
更新于2025-09-19 17:15:36