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1.
CNN-Based Vessel Meeting Knowledge Discovery From AIS Vessel Trajectories
Peng Chen, Shuang Liu, Niko Lukač, 2023, izvirni znanstveni članek

Opis: How to extract a collection of trajectories for different vessels from the raw AIS data to discover vessel meeting knowledge is a heavily studied focus. Here, the AIS database is created based on the raw AIS data after parsing, noise reduction and dynamic Ramer-Douglas-Peucker compression. Potential encountering trajectory pairs will be recorded based on the candidate meeting vessel searching algorithm. To ensure consistent features extracted from the trajectories in the same time period, time alignment is also adopted. With statistical analysis of vessel trajectories, sailing segment labels will be added to the input feature. All motion features and sailing segment labels are combined as input to one trajectory similarity matching method based on convolutional neural network to recognize crossing, overtaking or head-on situations for each potential encountering vessel pair, which may lead to collision if false actions are adopted. Experiments on AIS data show that our method is effective in classifying vessel encounter situations to provide decision support for collision avoidance.
Ključne besede: AIS Data, CNN, Dynamic Rammer-Douglas-Peucker, knowledge discovery, maneuvering pattern, traffic pattern, trajectory
Objavljeno v DKUM: 19.03.2024; Ogledov: 400; Prenosov: 408
.pdf Celotno besedilo (3,84 MB)
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2.
Research on vehicle re-identification algorithm based on fusion attention method
Peng Chen, Shuang Liu, Simon Kolmanič, 2023, izvirni znanstveni članek

Opis: The specific task of vehicle re-identification is how to quickly and correctly match the same vehicle in different scenarios. In order to solve the problem of inter-class similarity and environmental interference in vehicle images in complex scenes, one fusion attention method is put forward based on the idea of obtaining the distinguishing features of details-the mechanism for the vehicle re-identification method. First, the vehicle image is preprocessed to restore the image's attributes better. Then, the processed image is sent to ResNet50 to extract the features of the second and third layers, respectively. Then, the feature fusion is carried out through the two-layer attention mechanism for a network model. This model can better focus on local detail features, and global features are constructed and named SDLAU-Reid. In the training process, a data augmentation strategy of random erasure is adopted to improve the robustness. The experimental results show that the mAP and rank-k indicators of the model on VeRi-776 and the VehicleID are better than the results of the existing vehicle re-identification algorithms, which verifies the algorithm's effectiveness.
Ključne besede: vehicle re-identification, attention mechanism, key-point, local feature, feature fusion
Objavljeno v DKUM: 06.02.2024; Ogledov: 217; Prenosov: 16
.pdf Celotno besedilo (5,28 MB)
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3.
Measurement of two-particle correlations of hadrons in ▫$e^+ e^-$▫ collisions at Belle
Y.-C. Chen, Marko Bračko, Samo Korpar, Peter Križan, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek

Opis: The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at √s=10.52  GeV is reported. In this study, the 89.5  fb−1 of hadronic e+e− annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
Ključne besede: Particle & resonance production, Quark & gluon jets, Quark-gluon plasma
Objavljeno v DKUM: 24.08.2023; Ogledov: 320; Prenosov: 8
.pdf Celotno besedilo (634,71 KB)
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4.
Corrosion mechanisms for cemented soils in three different sulfate solutions
Pengju Han, Chao Ren, Xiaohong Bai, Frank Chen, 2015, izvirni znanstveni članek

Opis: In order to simulate and study the corrosion effects on the compressive strength of cemented soils that could be exposed in a polluted environment, a series of tests were conducted on cemented soil blocks cured with different concentrations of H2SO4, MgSO4, and Na2SO4 solutions. The test results show that the corrosion degree generally increases with the corrosion time and the solution concentration, while the compressive strength decreases with the increasing corrosion degree. The corrosion degree is highest for the Na2SO4 solution, followed by the MgSO4 and H2SO4 solutions. Namely, when the SO4 2- ion exists in a solution, the corrosion degree for the positive ions follows this descending order: Na+, Mg2+, and H+. X-ray diffraction (XRD) phase analyses were performed for the cemented soil samples after corrosion and ionic concentrations. The results show that the compressive strength decreases with an increase of the Mg2+ concentration in the MgSO4 solution and the Na+ concentration in the Na2SO4 solution. At the same time, the strength increases with an increase of the pH value of the H2SO4 solution. Based on the chemical analysis results, the corrosion of H2SO4 or MgSO4 solutions on cemented soils is deemed as a composite action involving the combined resolving and crystallizing corrosion processes. Furthermore, the corrosion of the Na2SO4 solution of cemented soil is a composite action consisting of dissolving and crystallizing.
Ključne besede: cemented soil, compressive strength, corrosion mechanism, sulfate, pollution, solution
Objavljeno v DKUM: 15.06.2018; Ogledov: 1656; Prenosov: 173
.pdf Celotno besedilo (305,84 KB)
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5.
Estimating piping potential in earth dams and levees using generalized neural networks
Xinhua Xue, Xingguo Yang, Xin Chen, 2014, izvirni znanstveni članek

Opis: Internal erosion and piping in embankments and their foundations is the main cause of failures and accidents to embankment dams. To estimate the risks of dam failure phenomenon, it is necessary to understand this phenomenon and to develop scientifically derived analytical models that are simpler, easier to implement, and more accurate than traditional methods for evaluation of piping potential. In this study, a generalized regression neural network (GRNN) technique has been applied for the assessment of piping potential, as well, due to its ability to fit complex nonlinear models. The performance of GRNN has been cross validated using the k-fold cross validation method technique. The GRNN model is found to have very good predictive ability and is expected to be very reliable for evaluation of piping potential.
Ključne besede: piping, generalized neural network, cross validation, BP neural network
Objavljeno v DKUM: 14.06.2018; Ogledov: 1161; Prenosov: 64
.pdf Celotno besedilo (463,20 KB)
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6.
Load transfer and stress in a piled gravity retaining wall
Qun Chen, Li Wan, Changrong He, Zihui Lai, 2010, izvirni znanstveni članek

Opis: The piled retaining wall is a new type of railway retaining structure in China. In the current design, the retaining wall, the beam and the piles are assumed to be independent components. Both the mutual action of the retaining wall, the piles and beam, and the influence of the soil or rock foundation on the structure are not fully considered, so that there are some limitations in the current design method. In this paper, using field observations and a three-dimensional finite-element analysis, the lateral earth pressure on the wall back, the stress distributions and the forces of the reinforcements in the beam and the pile were studied. The simulation results were in good agreement with the field observation data. These results revealed that the tensile stresses were very small and that these stresses were positive in most zones in the beam and the pile. It can also be observed that the tensile stresses or forces in the beam and pile obtained in this study were much smaller than those obtained using the current design method. This clarified the fact that the current design method used for the beam and the pile was very conservative and that it should be optimized to consider the effect of the foundation on the whole structure and the interactions among the different components.
Ključne besede: piled gravity retaining wall, field observation, finite-element analysis, stress, load transfer mechanism
Objavljeno v DKUM: 11.06.2018; Ogledov: 1079; Prenosov: 81
.pdf Celotno besedilo (558,92 KB)
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7.
The geo-mechanics behaviour of soft marine silts under a nearshore rubble-mound breakwater
Lien-Kwei Chien, Feng Tsung-Shen, Tsung-Ching Chen, 2009, izvirni znanstveni članek

Opis: In this study, the soft marine silts under a rubble-mound breakwater in Ma-Zu of west Taiwan are adopted as a test sample. The specimens were prepared by a new, remolded method at dry density and consolidated stresses. Tri-axial shear-strength tests were performed to evaluate the pore-water pressure and the shear strength. The test results show that the pore-water pressure increases gradually and is close to the critical values as the axial strain increases. In addition, under isotropic and K0 consolidation, both the c and c' of the soft marine silts were 0 kPa, which means that the silts do not have any shear resistance, just like fluid under a rubble-mound breakwater. Based on the linear-elasticity and the one-dimensional consolidation theory, the model of the settlement and stability was evaluated in SIGMA/W. The results show that the soft marine silts at the breakwater induced a displacement, greatly increasing with the filling rubble-mound loading. The figures and results can be referenced for a stability evaluation of the silt soil deposits under the rubble-mound breakwater. The results are useful for marine silts mechanics and a stability analysis for the planning, design, and related research on near-shore engineering.
Ključne besede: geo-mechanics behavior, soft marine silt, rubble-mound breakwater, settlement, numerical simulation mode
Objavljeno v DKUM: 06.06.2018; Ogledov: 1218; Prenosov: 167
.pdf Celotno besedilo (1,18 MB)
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8.
Simulating various terrestrial and UAV LiDAR scanning configurations for understory forest structure modelling
Marina Hämmerle, Niko Lukač, K.-C. Chen, Zsófia Koma, C.-K. Wang, K. Anders, B. Höfle, 2017, objavljeni znanstveni prispevek na konferenci

Opis: Information about the 3D structure of understory vegetation is of high relevance in forestry research and management (e.g., for complete biomass estimations). However, it has been hardly investigated systematically with state-of-the-art methods such as static terrestrial laser scanning (TLS) or laser scanning from unmanned aerial vehicle platforms (ULS). A prominent challenge for scanning forests is posed by occlusion, calling for proper TLS scan position or ULS flight line configurations in order to achieve an accurate representation of understory vegetation. The aim of our study is to examine the effect of TLS or ULS scanning strategies on (1) the height of individual understory trees and (2) understory canopy height raster models. We simulate full-waveform TLS and ULS point clouds of a virtual forest plot captured from various combinations of max. 12 TLS scan positions or 3 ULS flight lines. The accuracy of the respective datasets is evaluated with reference values given by the virtually scanned 3D triangle mesh tree models. TLS tree height underestimations range up to 1.84 m (15.30 % of tree height) for single TLS scan positions, but combining three scan positions reduces the underestimation to maximum 0.31 m (2.41 %). Combining ULS flight lines also results in improved tree height representation, with a maximum underestimation of 0.24 m (2.15 %). The presented simulation approach offers a complementary source of information for efficient planning of field campaigns aiming at understory vegetation modelling.
Ključne besede: forest structure, understory, laser scanning simulation, full waveform, 3D point cloud analysis, field campaign planning
Objavljeno v DKUM: 09.10.2017; Ogledov: 2115; Prenosov: 393
.pdf Celotno besedilo (3,71 MB)
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9.
Optimal distribution of incentives for public cooperation in heterogeneous interaction environments
Xiaojie Chen, Matjaž Perc, 2014, izvirni znanstveni članek

Opis: In the framework of evolutionary games with institutional reciprocity, limited incentives are at disposal for rewarding cooperators and punishing defectors. In the simplest case, it can be assumed that, depending on their strategies, all players receive equal incentives from the common pool. The question arises, however, what is the optimal distribution of institutional incentives? How should we best reward and punish individuals for cooperation to thrive? We study this problem for the public goods game on a scale-free network. We show that if the synergetic effects of group interactions are weak, the level of cooperation in the population can be maximized simply by adopting the simplest "equal distribution" scheme. If synergetic effects are strong, however, it is best to reward high-degree nodes more than low-degree nodes. These distribution schemes for institutional rewards are independent of payoff normalization. For institutional punishment, however, the same optimization problem is more complex, and its solution depends on whether absolute or degree-normalized payoffs are used. We find that degree-normalized payoffs require high-degree nodes be punished more lenient than low-degree nodes. Conversely, if absolute payoffs count, then high-degree nodes should be punished stronger than low-degree nodes.
Ključne besede: public cooperation, institutional reciprocity, scale-free network, punishment, reward
Objavljeno v DKUM: 10.07.2017; Ogledov: 1441; Prenosov: 401
.pdf Celotno besedilo (3,26 MB)
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10.
Probabilistic sharing solves the problem of costly punishment
Xiaojie Chen, Attila Szolnoki, Matjaž Perc, 2014, izvirni znanstveni članek

Opis: Cooperators that refuse to participate in sanctioning defectors create the secondorder free-rider problem. Such cooperators will not be punished because they contribute to the public good, but they also eschew the costs associated with punishing defectors. Altruistic punishers - those that cooperate and punish - are at a disadvantage, and it is puzzling how such behaviour has evolved. We show that sharing the responsibility to sanction defectors rather than relying on certain individuals to do so permanently can solve the problem of costly punishment. Inspired by the fact that humans have strong but also emotional tendencies for fair play, we consider probabilistic sanctioning as the simplest way of distributing the duty. In well-mixed populations the public goods game is transformed into a coordination game with full cooperation and defection as the two stable equilibria, while in structured populations pattern formation supports additional counterintuitive solutions that are reminiscent of Parrondoʼs paradox.
Ključne besede: social dynamics, networks, punishment, public goods, econophysics
Objavljeno v DKUM: 03.07.2017; Ogledov: 1169; Prenosov: 403
.pdf Celotno besedilo (1,52 MB)
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