- 标题
- 摘要
- 关键词
- 实验方案
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Self-calibration of projective camera based on trajectory basis
摘要： To calibrate the projective camera, this paper presents a linear method for self-calibration of a projective camera based on the representing of deforming object by the trajectory basis. The trajectory basis can be modeled compactly in the domain of the Discrete Cosine Transform (DCT) basis vectors which can be predefined independent of the observed images, and the number of unknowns can be significantly reduced. At the same time, the camera self-calibration becomes a linear optimal problem, which can improve the robustness of the algorithm. The experiments with both simulate and real data show that the presented method can effectively calibrate the camera.
关键词： Non-rigid,Trajectory basis.,Self-calibration
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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Quantum error correction using weak measurements
摘要： The standard quantum error correction protocols use projective measurements to extract the error syndromes from the encoded states. We consider the more general scenario of weak measurements, where only partial information about the error syndrome can be extracted from the encoded state. We construct a feedback protocol that probabilistically corrects the error based on the extracted information. Using numerical simulations of one-qubit error correction codes, we show that our error correction succeeds for a range of the weak measurement strength, where (a) the error rate is below the threshold beyond which multiple errors dominate, and (b) the error rate is less than the rate at which weak measurement extracts information. We observe that error correction based on projective measurements is always superior to that based on weak measurements; so the latter is worthwhile only if the former is unavailable due to some reason, and error correction with too small a measurement strength should be avoided.
关键词： Projective measurement,Quantum error correction,Weak measurement,Quantum trajectory
更新于2025-09-23 15:22:29
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Image and data processing algorithms for identifying cell-bound membrane vesicle trajectories and movement information
摘要： This DIB article provides details about the trajectory identification and data processing algorithms used in the article "Dynamic single-vesicle tracking of cell-bound membrane vesicles on resting, activated, and cytoskeleton-disrupted cells" (Zhang et al.) [1]. The algorithm identifies vesicles on cell membranes from series of undyed grayscale images captured by the confocal microscope based on contrast differences and then trajectories of vesicles are obtained by analyzing their positions in consecutive images. Once the trajectories have been obtained, other quantitative movement information, such as moving speed, direction and acceleration, are derived by standard dynamic relations.
关键词： MATLAB algorithms,Vesicle tracking,Trajectory tracing,Confocal microscopy,Image processing
更新于2025-09-23 15:22:29
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[IEEE 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2018.11.26-2018.11.30)] 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - The Problem of Determination of Coordinates of Unmanned Aerial Vehicles Using a Two-Position System Ground Radar
摘要： the features of modern methods for detecting and determining the coordinates of small unmanned aerial vehicles using a two-position ground radar system are considered. It is proposed to use the methods developed for multi-sensor radar systems. The limitations and advantages of the two-position radar system are shown. The main potential characteristics of the system and the corresponding restrictions on the conditions of its effective application are determined. Potential characteristics are obtained by simulation methods using mathematical models built on the basis of experimental data.
关键词： two-position system,radar system,detection of objects,trajectory coordinates,unmanned aerial vehicle,determination of coordinates,air object,joint information processing
更新于2025-09-23 15:22:29
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Efficient Analysis of Inhomogeneous Dielectric Waveguides With Dielectric Strips and Microstrips Using Discrete Mode Matching Method
摘要： In this paper a smooth starter, based on a dc/dc Buck power converter, for the angular velocity trajectory tracking task of a dc permanent magnet motor is presented. To this end, a hierarchical controller is designed, which is integrated by a control associated with the dc motor based on differential flatness at the high level, and a control related with the dc/dc Buck converter based on a cascade control scheme at the low level. The control at the high level allows the dc motor angular velocity to track a desired trajectory and also provides the desired voltage profile that must be tracked by the output voltage of the dc/dc Buck power converter. In order to assure the latter, a cascade control at the low level is designed, considering a sliding mode control for the inner current loop and a proportional-integral control for the outer voltage loop. The hierarchical controller is tested through experiments using MATLAB-Simulink and the DS1104 board from dSPACE. The obtained results show that the desired angular velocity trajectory is well tracked under abrupt variations in the system parameters and that the controller is robust in such operation conditions, confirming the validity of the proposed controller.
关键词： sliding mode control (SMC),Cascade control,differential flatness,dc/dc Buck power converter,trajectory tracking,hierarchical controller,dc motor,proportional-integral (PI) control,smooth starter
更新于2025-09-23 15:21:01
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Recovering Missing Trajectory Data for Mobile Laser Scanning Systems
摘要： Trajectory data are often used as important auxiliary information in preprocessing and extracting the target from mobile laser scanning data. However, the trajectory data stored independently may be lost and destroyed for various reasons, making the data unavailable for the relevant models. This study proposes recovering the trajectory of the scanner from point cloud data following the scanning principles of a rotating mirror. Two approaches are proposed from di?erent input conditions: Ordered three-dimensional coordinates of point cloud data, with and without acquisition time. We recovered the scanner’s ground track through road point density analysis and restored the position of the center of emission of the laser based on plane reconstruction on a single scanning line. The validity and reliability of the proposed approaches were veri?ed in the four typical urban, rural, winding, and viaduct road environments using two systems from di?erent manufacturers. The result deviations of the ground track and scanner trajectory from their actual position were a few centimeters and less than 1 decimeter, respectively. Such an error is su?ciently small for the trajectory data to be used in the relevant algorithms.
关键词： point density,scanner trajectory,scanning line,mobile laser scanning
更新于2025-09-23 15:21:01
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Reconstruction of Airborne Laser Scanner Trajectory From Data
摘要： Multi-echo airborne laser scanner (ALS) has shown increasing utility for forestry applications in the two past decades. Among the numerous algorithms developed to process ALS data on forest environments some require to know actual sensor trajectory and deduced angles of incidence. However, sensor trajectory is not part of the ALS standard LAS file format and is often not delivered with point clouds. Scan angle is usually specified with a one byte precision or not given at all. This paper presents a method for the reconstruction of the sensor trajectory from a multi-echo ALS point cloud. It is based on the intersection of multi-echo pulses and was tested on three data sets acquired over a deciduous, a tropical and a mountainous forest, respectively. It allows sensor location estimate and scan angle estimate with less than 25 cm and 2·10-2° error.
关键词： Lidar,Trajectory Inversion,Airborne Laser Scanner,Forest
更新于2025-09-23 15:21:01
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The Ball-Based Origami Theorem and a Glimpse of Holography for Traversing Flows
摘要： This paper describes a mechanism by which a traversally generic ?ow v on a smooth connected (n + 1)-dimensional manifold X with boundary produces a compact n-dimensional C W -complex T (v), which is homotopy equivalent to X and such that X embeds in T (v) × R. The C W -complex T (v) captures some residual information about the smooth structure on X (such as the stable tangent bundle of X ). Moreover, T (v) is obtained from a simplicial origami map O : Dn → T (v), whose source space is a ball Dn ? ? X . The ?bers of O have the cardinality (n + 1) at most. The knowledge of the map O, together with the restriction to Dn of a Lyapunov function : X → R for v, make it possible to reconstruct the topological type of the pair (X , F(v)), were F(v) is the 1-foliation, generated by v. This fact motivates the use of the word “holography” in the title. In a qualitative formulation of the holography principle, for a massive class of ODE’s on a given compact manifold X , the solutions of the appropriately staged boundary value problems are topologically rigid.
关键词： Boundary value problems,Trajectory spaces,Manifolds with boundary,Holography,Traversing ?ows
更新于2025-09-23 15:21:01
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Accurate trajectory alignment in cold-atom interferometers with separated laser beams
摘要： Cold-atom interferometers commonly face systematic effects originating from the coupling between the trajectory of the atomic wave packet and the wavefront of the laser beams driving the interferometer. Detrimental for the accuracy and the stability of such inertial sensors, these systematics are particularly enhanced in architectures based on spatially separated laser beams. Here we analyze the effect of a coupling between the relative alignment of two separated laser beams and the trajectory of the atomic wave packet in a four-light-pulse cold-atom gyroscope operated in fountain configuration. We present a method to align the two laser beams at the 0.2 μrad level and to determine the optimal mean velocity of the atomic wave packet with an accuracy of 0.2 mm s?1. Such fine tuning constrains the associated gyroscope bias to a level of 1 × 10?10 rad s?1. In addition, we reveal this coupling using the point-source interferometry technique by analyzing single-shot time-of-flight fluorescence traces, which allows us to measure large angular misalignments between the interrogation beams. The alignment method which we present here can be employed in other sensor configurations and is particularly relevant to emerging gravitational wave detector concepts based on cold-atom interferometry.
关键词： trajectory alignment,laser beams,point-source interferometry,cold-atom interferometers,gyroscope
更新于2025-09-23 15:19:57