6,247 research outputs found
Four-point combined DE/FE algorithm for brittle fracture analysis of laminated glass
AbstractA four-point combined DE/FE algorithm is proposed to constrain the rotation of a discrete element about its linked point and analyze the cracks propagation of laminated glass. In this approach, four linked points on a discrete element are combined with four nodes of the corresponding surface of a finite element. The penalty method is implemented to calculate the interface force between the two subdomains, the finite element (FE) and the discrete element (DE) subdomains. The sequential procedure of brittle fracture is described by an extrinsic cohesive fracture model only in the DE subdomain. An averaged stress tensor for granular media, which is automatically symmetrical and invariant by translations, is used to an accurate calculation of the averaged stress of the DE. Two simple cases in the elastic range are given to certify the effectiveness of the combined algorithm and the averaged stress tensor by comparing with the finite element method and the mesh-size dependency of the combined algorithm and the cohesive model is also investigated. Finally, the impact fracture behavior of a laminated glass beam is simulated, and the cracks propagation is compared with experimental results showing that the theory in this work can be used to predict some fracture characteristics of laminated glass
Study on transient voltage distribution characteristics of transformer windings
Very fast transient overvoltage (VFTO) with large waveform steepness and high amplitude can cause great harm to winding insulation of transformers and other equipment connected to it. Therefore, a transformer winding model is designed and described in this paper. Transient overvoltage test is carried out by pinning method and
non-contact measuring sensor respectively. Then the simulation results
are compared with those of VFTO distribution calculation program for
transformer equipment. The results show that the simulation results are
close to the actual test results. Finally, combining with the experimental
measurement and simulation data, the potential distribution in transformer windings under the effect of fast transient overvoltage is analysed to guide the overvoltage protection of transformer
winding insulation
CoLight: Learning Network-level Cooperation for Traffic Signal Control
Cooperation among the traffic signals enables vehicles to move through
intersections more quickly. Conventional transportation approaches implement
cooperation by pre-calculating the offsets between two intersections. Such
pre-calculated offsets are not suitable for dynamic traffic environments. To
enable cooperation of traffic signals, in this paper, we propose a model,
CoLight, which uses graph attentional networks to facilitate communication.
Specifically, for a target intersection in a network, CoLight can not only
incorporate the temporal and spatial influences of neighboring intersections to
the target intersection, but also build up index-free modeling of neighboring
intersections. To the best of our knowledge, we are the first to use graph
attentional networks in the setting of reinforcement learning for traffic
signal control and to conduct experiments on the large-scale road network with
hundreds of traffic signals. In experiments, we demonstrate that by learning
the communication, the proposed model can achieve superior performance against
the state-of-the-art methods.Comment: 10 pages. Proceedings of the 28th ACM International on Conference on
Information and Knowledge Management. ACM, 201
DAD vision: opto-electronic co-designed computer vision with division adjoint method
The miniaturization and mobility of computer vision systems are limited by
the heavy computational burden and the size of optical lenses. Here, we propose
to use a ultra-thin diffractive optical element to implement passive optical
convolution. A division adjoint opto-electronic co-design method is also
proposed. In our simulation experiments, the first few convolutional layers of
the neural network can be replaced by optical convolution in a classification
task on the CIFAR-10 dataset with no power consumption, while similar
performance can be obtained
High-occupancy Vehicle Lanes and Tradable Credits Scheme for Traffic Congestion Management: A Bilevel Programming Approach
High-occupancy vehicle (HOV) lanes, which are designed so as to encourage more people to use high-capacity travel modes and thus move more people in a single roadway lane, have been implemented as a lane management measure to deal with the growing traffic congestion in practice. However, the implementation has shown that some HOV lanes are not able to achieve the expected effects without proper HOV lane settings. In this study, the tradable credits scheme (TCS) is introduced to improve the HOV lane management and an optimal capacity of HOV lanes in a multilane highway is investigated to match TCSs. To approach the investigation, a bilevel programming model is proposed. The upper-level represents the decision of the highway authority and the lower-level follows the commuters’ user equilibrium with deterministic demand. The potential influence of TCSs is further investigated within the proposed framework. A modified genetic algorithm is proposed to solve the bilevel programming model. Numerical examples demonstrate that combining TCSs with the HOV lane management can obviously mitigate traffic congestion.</p
Realizing degree sequences with graphs having nowhere-zero 3-flows
The following open problem was proposed by Archdeacon: Characterize all graphical sequences π such that some realization of π admits a nowhere-zero 3-flow. The purpose of this paper is to resolve this problem and present a complete characterization: A graphical sequence π = (d I,d2,...,dn) with minimum degree at least two has a realization that admits a nowhere-zero 3-flow if and only if π ≠ (34,2), (k,3k), (k2,3k-1), where k is an odd integer. © 2008 Society for Industrial and Applied Mathematics.published_or_final_versio
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