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过滤筛选
- 2018
- railway track
- kinematic characteristics
- stereo vision
- image blur
- distance estimation
- control system
- depth of field
- video monitoring
- Optoelectronic Information Science and Engineering
- Bauman Moscow State Technical University
- Moscow State University of Railway Engineering
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Absolute distance measurement based on spectral interferometry using femtosecond optical frequency comb
摘要： We demonstrated an absolute distance measurement method based on the frequency folding e?ect using the spectral interferometry of femtosecond optical frequency comb. And the investigation was carried out on the ranging accuracy in?uence of the phase noise in the traditional complicated phase unwrapping method via band-pass ?lter and Fourier Transform. To reduce the e?ects of the phase noise, we proposed the non-?ltered and di?erential envelop phase demodulation method, and its robustness was illustrated with a standard deviation of 75 nm for the stability of single point measurements. Further, through the extension of the non-ambiguity range, we achieved a resolution of better than 30 ??m in a long distance measurements range of 70 m, yielding a relative precision of 3.1 × 10 ? 7.
关键词： Spectral interferometry,Optical frequency comb,Absolute distance measurement
更新于2025-11-28 14:23:57
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An Image Segmentation Method Based on Improved Regularized Level Set Model
摘要： When the level set algorithm is used to segment an image, the level set function must be initialized periodically to ensure that it remains a signed distance function (SDF). To avoid this defect, an improved regularized level set method-based image segmentation approach is presented. First, a new potential function is defined and introduced to reconstruct a new distance regularization term to solve this issue of periodically initializing the level set function. Second, by combining the distance regularization term with the internal and external energy terms, a new energy functional is developed. Then, the process of the new energy functional evolution is derived by using the calculus of variations and the steepest descent approach, and a partial differential equation is designed. Finally, an improved regularized level set-based image segmentation (IRLS-IS) method is proposed. Numerical experimental results demonstrate that the IRLS-IS method is not only effective and robust to segment noise and intensity-inhomogeneous images but can also analyze complex medical images well.
关键词： image segmentation,energy functional,level set,distance regularization term
更新于2025-09-23 15:23:52
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The region based MMTD energy function for image segmentation
摘要： This paper presents a region-based model based on measure of medium truth degree for image segmentation. Firstly, a new energy function based on measure of medium truth degree is constructed. To enhance the robustness against noise, a noise penalty term which is built by spatial distance measure is embedded to the conventional active contour energy function. Then local information is added to the internal and external energy term of the conventional active contour energy function to deal with intensity inhomogeneity images. Finally, to obtain more accurate and smoother boundary, a new stop function is introduced into the boundary smooth term of the conventional active contour energy function. Experiments results demonstrate that relatively complete and accurate boundaries can be obtained by the proposed model compared with the state-of-art methods on aurora images, images with intensity inhomogeneity, images with multi-objects, natural images, medical images.
关键词： Spatial distance measure,Local information,Graph cuts,Measure of medium truth degree
更新于2025-09-23 15:23:52
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Pairwise nonclassical correlations for superposition of Dicke states via local quantum uncertainty and trace distance discord
摘要： The pairwise nonclassical correlations for two-qubit states, extracted from multi-qubit system with exchange symmetry and parity, are quanti?ed by local quantum uncertainty and trace distance discord. The explicit expressions of local quantum uncertainty and geometric trace distance discord for Dicke states and their superpositions are given. A comparison between the two quantum correlations quanti?ers is discussed.
关键词： Pairwise nonclassical correlations,Trace distance discord,Dicke states,Local quantum uncertainty
更新于2025-09-23 15:23:52
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Time evolution of entanglement and trace distance in an atom-cavity system described with random walk and non-random walk states
摘要： An atom-cavity system consists of an atom or group of atoms inside a cavity. When an atom in cavity is stimulated by a laser pump, it is affected by the atom-field interaction shows the qusi- random walk behavior. This can change the entanglement and trace distance of system. In this work, the change entanglement and trace distance of system in two different cases -namely- the random walk and non-random walk is considered. The descriptive system is a two -level atom in the electrodynamics cavity based on the Jayne’s-Cummings model, which is stimulated by two longitudinal and transverse laser pumps. The results show that the consideration of the random walk case for the atom changes in the amount of entanglement can be seen as the phenomenon of sudden death and birth of entanglement. It results in its rate of changes to be increased. In contrast to the non-random walk case, this rate is increased and decreased more quickly compared to the random walk case. The maximum amount of entanglement in each case is the same, but the minimum in random walk case is less than that of non-random walk case.
关键词： entanglement,random walk,trace distance,Cavity,laser pump
更新于2025-09-23 15:23:52
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Analysis of trajectory similarity and configuration similarity in on-the-fly surface-hopping simulation on multi-channel nonadiabatic photoisomerization dynamics
摘要： We propose an “automatic” approach to analyze the results of the on-the-fly trajectory surface hopping simulation on the multi-channel nonadiabatic photoisomerization dynamics by considering the trajectory similarity and the configuration similarity. We choose a representative system phytochromobilin (PΦB) chromophore model to illustrate the analysis protocol. After a large number of trajectories are obtained, it is possible to define the similarity of different trajectories by the Fréchet distance and to employ the trajectory clustering analysis to divide all trajectories into several clusters. Each cluster in principle represents a photoinduced isomerization reaction channel. This idea provides an effective approach to understand the branching ratio of the multi-channel photoisomerization dynamics. For each cluster, the dimensionality reduction is employed to understand the configuration similarity in the trajectory propagation, which provides the understanding of the major geometry evolution features in each reaction channel. The results show that this analysis protocol not only assigns all trajectories into different photoisomerization reaction channels but also extracts the major molecular motion without the requirement of the pre-known knowledge of the active photoisomerization site. As a side product of this analysis tool, it is also easy to find the so-called “typical” or “representative” trajectory for each reaction channel.
关键词： trajectory similarity,multi-channel nonadiabatic photoisomerization dynamics,Fréchet distance,dimensionality reduction,phytochromobilin chromophore,on-the-fly surface-hopping simulation,configuration similarity,clustering analysis
更新于2025-09-23 15:23:52
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: A Novel Similarity Measure for Matching Local Image Descriptors
摘要： mp-dissimilarity is a recently proposed data-dependence similarity measure. In the literature, how mp-dissimilarity is generally used for matching local image descriptors has been formalized, and three matching strategies have been proposed by incorporating (cid:96)p-norm distance and mp-dissimilarity. Each of these three matching strategies is essentially a two-round matching process that utilizes (cid:96)p-norm distance and mp-dissimilarity individually. This paper presents two novel similarity measures for matching local image descriptors. The first similarity measure normalizes and weights the similarities that are calculated using (cid:96)p-norm distance and mp-dissimilarity, respectively. The second similarity measure involves a novel calculation that takes into account both spatial distance and data distribution between descriptors. The proposed similarity measures are extensively evaluated on a few image registration benchmark data sets. Experimental results will demonstrate that the proposed similarity measures achieve higher matching accuracy and are able to attain better recall results when registering multi-modal images compared with the existing matching strategies that combine (cid:96)p-norm distance and mp-dissimilarity.
关键词： local descriptors,accuracy,mp-dissimilarity,image registration,(cid:96)p-norm distance,Similarity measure
更新于2025-09-23 15:23:52
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Functional Diversity in the Retina Improves the Population Code
摘要： Within a given brain region, individual neurons exhibit a wide variety of different feature selectivities. Here, we investigated the impact of this extensive functional diversity on the population neural code. Our approach was to build optimal decoders to discriminate among stimuli using the spiking output of a real, measured neural population and compare its performance against a matched, homogeneous neural population with the same number of cells and spikes. Analyzing large populations of retinal ganglion cells, we found that the real, heterogeneous population can yield a discrimination error lower than the homogeneous population by several orders of magnitude and consequently can encode much more visual information. This effect increases with population size and with graded degrees of heterogeneity. We complemented these results with an analysis of coding based on the Chernoff distance, as well as derivations of inequalities on coding in certain limits, from which we can conclude that the beneficial effect of heterogeneity occurs over a broad set of conditions. Together, our results indicate that the presence of functional diversity in neural populations can enhance their coding fidelity appreciably. A noteworthy outcome of our study is that this effect can be extremely strong and should be taken into account when investigating design principles for neural circuits.
关键词： retina,neural coding,discrimination error,mutual information,functional diversity,Chernoff distance,population code,heterogeneity
更新于2025-09-23 15:23:52
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Multi-Scale Object Histogram Distance for LCCD Using Bi-Temporal Very-High-Resolution Remote Sensing Images
摘要： To improve the performance of land-cover change detection (LCCD) using remote sensing images, this study utilises spatial information in an adaptive and multi-scale manner. It proposes a novel multi-scale object histogram distance (MOHD) to measure the change magnitude between bi-temporal remote sensing images. Three major steps are related to the proposed MOHD. Firstly, multi-scale objects for the post-event image are extracted through a widely used algorithm called the fractional net evaluation approach. The pixels within a segmental object are taken to construct the pairwise frequency distribution histograms. An arithmetic frequency-mean feature is then defined from the red, green and blue band histogram. Secondly, bin-to-bin distance is adapted to measure the change magnitude between the pairwise objects of bi-temporal images. The change magnitude image (CMI) of the bi-temporal images can be generated through object-by-object. Finally, the classical binary method Otsu is used to divide the CMI to a binary change detection map. Experimental results based on two real datasets with different land-cover change scenes demonstrate the effectiveness of the proposed MOHD approach in detecting land-cover change compared with three widely used existing approaches.
关键词： remote sensing application,detection algorithm,land use and land cover,histogram distance
更新于2025-09-23 15:23:52
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Recovering distance information in spectral domain interferometry
摘要： This work evaluates the performance of the Complex Master Slave (CMS) method, that processes the spectra at the interferometer output of a spectral domain interferometry device without involving Fourier transforms (FT) after data acquisition. Reliability and performance of CMS are compared side by side with the conventional method based on FT, phase calibration with dispersion compensation (PCDC). We demonstrate that both methods provide similar results in terms of resolution and sensitivity drop-off. The mathematical operations required to produce CMS results are highly parallelizable, allowing real-time, simultaneous delivery of data from several points of different optical path differences in the interferometer, not possible via PCDC.
关键词： distance measurement,spectral domain interferometry,optical coherence tomography,dispersion compensation,phase calibration,Complex Master Slave,Fourier transforms
更新于2025-09-23 15:23:52