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Given a database of spatial trajectories reporting the movement of a set of objects in a time frame, the problem is to discover the groups of objects that stay in close proximity within a geographical area for a significant time. To deal with the problem, techniques for the discovery of collective patterns, e.g. the meeting pattern, have been proposed. Such techniques, however, impose stringent constraints...
The paper provides new results for testing the flow-invariance of time-dependent sets with arbitrary shapes, with respect to trajectories of continuous-time nonlinear systems. The approach represents a generalization of a criterion used in the qualitative analysis of ordinary differential equations with solutions in closed sets with hyper-rectangular form. Given a nonlinear dynamical system for investigation,...
This work introduces a novel surface registration method based on foliation. A foliation decomposes the surface into a family of closed loops, such that the decomposition has local tensor product structure. By projecting each loop to a point, the surface is collapsed into a graph. Two homeomorphic surfaces with consistent foliations can be registered by first matching their foliation graphs, then...
To research the effect on the canard rudder aerodynamic layout for the projectile correction, the steering gear model under different aerodynamic layout was established. Various kinds of aerodynamic parameters were obtained through simulation. Through the establishment of the ballistic model of suitable for less spin correction projectiles, the capability of correcting has been received under the...
This paper considers the multi-camera motion segmentation problem using unsynchronized videos: given two video clips containing several moving objects, captured by unregistered, unsynchronized cameras with different viewpoints, our goal is to assign features to moving objects in the scene. This problem challenges existing methods, due to the lack of registration information and correspondences across...
In this paper, we study the problem of facial expression recognition using a novel space-time geometric representation. We describe the temporal evolution of facial landmarks as parametrized trajectories on the Riemannian manifold of positive semidefinite matrices of fixed-rank. Our representation has the advantage to bring naturally a second desirable quantity when comparing shapes – the spatial...
Analyzing data representing multifarious trajectories is central to the many fields in Science and Engineering; for example, trajectories representing a tennis serve, a gymnast’s parallel bar routine, progression/remission of disease and so on. We present a novel geometric algorithm for performing statistical analysis of trajectories with distinct number of samples representing longitudinal (or temporal)...
Visualization combining space and time in a single display called “space time cube (STC)” is used for visualizing spatio-temporal movement data. An STC enables us to explore not only shapes and positions of vehicle trajectories but also their temporal distributions. However, it is difficult for users to manually find optimal viewpoints for understanding such characteristics of trajectories. In this...
Trajectory planning in airborne networks is a primary application of Unmanned Aerial Vehicle (UAV) communication. The literature contains algorithms focusing on collision avoidance, intelligent task assignment and path planning among UAVs. Cooperative schemes exist in which the UAVs communicate with each other to reach a consensus on how each vehicle will take up one trajectory at a time efficiently...
Trajectory planning using Mixed Integer Linear Programming (MILP) is a powerful approach because vehicle dynamics and other constraints can be taken into account. However, it is currently severely limited by poor scalability. This paper presents a new approach which improves the scalability regarding the amount of obstacles and the distance between the start and goal positions. While previous approaches...
An increasing number of people use smartphone applications to plan their trips. Unfortunately, for various reasons, bus trips suggested by such applications are not as reliable as other trip types (e.g. by car, on foot, or by bicycle), which can result in excessive waiting time, or even the need to revise a planned trip. Traditional punctuality-based bus service reliability metrics do not capture...
With the advance of mobile electronic devices and the development of positioning technology, a large volume of spatio-temopral data are collected in the form of desultorily data streams, which contain a lot of potential information. In this study, we focus on discovering the composition relationships between observation moving objects in a long period. Such research can be widely used in military...
This paper focuses on the control of dynamical systems under the case that actual reference signals can not be available in real time. In such case, although predicted values are used as reference signals, the prediction errors degrade the control performance of the systems. To overcome this problem, the previous work presented the prediction governor which shapes predicted values. However, the previous...
Nowadays the task of tracking pedestrians is often addressed within a tracking-by-detection framework, which in most cases entails that the position of each target has been detected before tracking begins. However in some cases, a pedestrian who is being tracked may be obscured by other targets or obstacles, and during this period they may change their trajectory or speed (track drift), and sometimes...
In this paper an accuracy of local motion planning based on the generalized Campbell-Baker-Hausdorff-Dynkin formula was evaluated for a few nonholonomic robotic systems. For a given set of controls, an exact trajectory is computable via an integration of equations of motion. This reference trajectory is compared with with a trajectory based on shrinked versions of the gCBHD formula. An impact of controls...
In this paper, a new potential field approach is proposed for trajectory planning and control in autonomous vehicles. The potential field of the surrounding environment is generated including vehicles, road boundaries and lane centers. Based on the predicted positions of the vehicles, the location of the ego vehicle and the surrounding potentials are synchronized. In addition, the potential fields...
For service robots to be well received in our daily lives, it is desirable that they appear as friendly as possible rather than some unfriendly characters. While a robot's physical appearance influences this perception, its behavior also has an impact. In order to be sure that a specific robot behavior will be correctly perceived, we propose to its potential users to shape the robot's behavior. In...
Field emission from “nano diodes” encounter strong deviations from the tunneling barrier presupposed in Fowler Nordheim theory. Modifications to the emission barrier are modeled using a hyperbolic geometry to find trajectories along which Gamow factor is found; a quadratic equivalent potential is determined, and a shape factor method is used to evaluate the total current from a protrusion or wedge...
We present an approach to reconstruct the 3D shape of multiple deforming objects from incomplete 2D trajectories acquired by a single camera. Additionally, we simultaneously provide spatial segmentation (i.e., we identify each of the objects in every frame) and temporal clustering (i.e., we split the sequence into primitive actions). This advances existing work, which only tackled the problem for...
Recent analyses have showed that moving target smears in synthetic aperture radar (SAR) imagery are not constrained to have the shapes of simple parabolas but instead can have a wide variety of two-dimensional (2D) shapes, including self-crossing signatures. The current study investigates the properties of the central smear contour under the conditions of varying the target speed difference for targets...
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