365 research outputs found
Ground-VIO: Monocular Visual-Inertial Odometry with Online Calibration of Camera-Ground Geometric Parameters
Monocular visual-inertial odometry (VIO) is a low-cost solution to provide
high-accuracy, low-drifting pose estimation. However, it has been meeting
challenges in vehicular scenarios due to limited dynamics and lack of stable
features. In this paper, we propose Ground-VIO, which utilizes ground features
and the specific camera-ground geometry to enhance monocular VIO performance in
realistic road environments. In the method, the camera-ground geometry is
modeled with vehicle-centered parameters and integrated into an
optimization-based VIO framework. These parameters could be calibrated online
and simultaneously improve the odometry accuracy by providing stable
scale-awareness. Besides, a specially designed visual front-end is developed to
stably extract and track ground features via the inverse perspective mapping
(IPM) technique. Both simulation tests and real-world experiments are conducted
to verify the effectiveness of the proposed method. The results show that our
implementation could dramatically improve monocular VIO accuracy in vehicular
scenarios, achieving comparable or even better performance than state-of-art
stereo VIO solutions. The system could also be used for the auto-calibration of
IPM which is widely used in vehicle perception. A toolkit for ground feature
processing, together with the experimental datasets, would be made open-source
(https://github.com/GREAT-WHU/gv_tools)
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Risk Response for Municipal Solid Waste Crisis Using Ontology-Based Reasoning
Many cities in the world are besieged by municipal solid waste (MSW). MSW not only pollutes the ecological environment but can even induce a series of public safety crises. Risk response for MSW needs novel changes. This paper innovatively adopts the ideas and methods of semantic web ontology to build an ontology-based reasoning system for MSW risk response. Through the integration of crisis information and case resources in the field of MSW, combined with the reasoning ability of Semantic Web Rule Language (SWRL), a system of rule reasoning for risk transformation is constructed. Knowledge extraction and integration of MSW risk response can effectively excavate semantic correlation of crisis information along with key transformation points in the process of crisis evolution through rule reasoning. The results show that rule reasoning of transformation can effectively improve intelligent decision-making regarding MSW risk response
Perceived family relationships and social participation through sports of urban older adults living alone: An analysis of the mediating effect of self-respect levels
IntroductionThe perception of good family relationship is an important factor to promote social participation through sports of older adults living alone. This study explores the influence of perceived family relationship on sports sociability and its group differences, and then discusses the mediating effect of self-respect.MethodsBased on the survey data of 2,801 older adults living alone in Chengdu, Shanghai, Guangzhou, Hohhot, and Dalian, the quantitative index of their “activeness in social participation through sports” was constructed. The OLS model, the Ologit model, the instrumental variable method and the mediating effect were used to explore the influence mechanism of perceived family relationships of urban older adults living alone on their sport participation.ResultsThe results demonstrate that: (1) Older adults 's activeness in sport participation in China is generally at a low level; (2) perceived family relationships have an impact on activeness in sport participation, i.e. positive family relationships will increase their activeness in sport participation, and there are evident gender differences in this tendency; (3) there are regional differences in the activeness in SPS among the older adults living alone in urban areas, and perceived family relationships in first-tier and second-tier cities have a more significant impact on their activeness in sport participation; (4) the mediating effect analysis shows that perceived family relationships can indirectly promote urban old adults' activeness in sport participation through the reconstruction of their self-respect, and this is more pronounced in women.DiscussionTherefore, the important role of families cannot be ignored in promoting sport participation of the older adults
Real-time quantum feedback prepares and stabilizes photon number states
Feedback loops are at the heart of most classical control procedures. A
controller compares the signal measured by a sensor with the target value. It
adjusts then an actuator in order to stabilize the signal towards its target.
Generalizing this scheme to stabilize a micro-system's quantum state relies on
quantum feedback, which must overcome a fundamental difficulty: the
measurements by the sensor have a random back-action on the system. An optimal
compromise employs weak measurements providing partial information with minimal
perturbation. The controller should include the effect of this perturbation in
the computation of the actuator's unitary operation bringing the incrementally
perturbed state closer to the target. While some aspects of this scenario have
been experimentally demonstrated for the control of quantum or classical
micro-system variables, continuous feedback loop operations permanently
stabilizing quantum systems around a target state have not yet been realized.
We have implemented such a real-time stabilizing quantum feedback scheme. It
prepares on demand photon number states (Fock states) of a microwave field in a
superconducting cavity and subsequently reverses the effects of
decoherence-induced field quantum jumps. The sensor is a beam of atoms crossing
the cavity which repeatedly performs weak quantum non-demolition measurements
of the photon number. The controller is implemented in a real-time computer
commanding the injection, between measurements, of adjusted small classical
fields in the cavity. The microwave field is a quantum oscillator usable as a
quantum memory or as a quantum bus swapping information between atoms. By
demonstrating that active control can generate non-classical states of this
oscillator and combat their decoherence, this experiment is a significant step
towards the implementation of complex quantum information operations.Comment: 12 pages, 4 figure
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