Transform Coding in the VVC Standard Zhao, Xin; Kim, Seung-Hwan; Zhao, Yin ...
IEEE transactions on circuits and systems for video technology,
10/2021, Letnik:
31, Številka:
10
Journal Article
Recenzirano
Odprti dostop
In the past decade, the development of transform coding techniques has achieved significant progress and several advanced transform tools have been adopted in the new generation Versatile Video ...Coding (VVC) standard. In this paper, a brief history of transform coding development during VVC standardization is presented, and the transform coding tools in the VVC standard are described in detail together with their initial design, incremental improvements and implementation aspects. To improve coding efficiency, four new transform coding techniques are introduced in VVC, which are namely Multiple Transform Selection (MTS), Low-Frequency Non-separable Secondary Transform (LFNST) and Sub-Block Transform (SBT), as well as a large (64-point) type-2 DCT. The experimental results on VVC reference software (VTM-9.0) show that average 4.5% and 3.6% overall coding gain can be achieved by the VVC transform coding tools for All Intra and Random Access configurations, respectively.
•Crack initiates along local minimum or global minimum direction.•negative value of T-stress makes the crack move toward the loading direction (T-axis).•When σ90 = σz, Hill-48, Hill-90, and Barlat ...show the same crack initiation angle.•when σ90 < σ0, crack tends to move toward local coordinate placed on crack tip.
In this work, five different yield criteria have been used, maximum tangential stress (MTS), maximum energy release rate (MERR), Hill-48, Hill-90, and Barlat-93, in order to determine crack initiation angle. A study is performed to investigate the effect of T-stress on crack initiation angle. For this purpose, the elastic–plastic core region is plotted, and the R-criterion suggests that the crack initiates along local minimum (negative value) or global minimum (positive value) direction depending on the stress state at the crack tip. It is found that a negative value of T-stress makes the crack move toward the loading direction (T-axis), or in other words, the crack initiation angle decreases. It also turns out that MERR and Barlat criteria show a better result for crack initiation angle. The yield surface and elastic–plastic core region have also been plotted for different tensile strengths. For the case when transverse tensile strength equals to z-direction tensile strength, Hill-48, Hill-90, and Barlat show the same yield surface, and approximately, the same crack initiation angle. Also, when transverse tensile strength is smaller than longitudinal tensile strength, crack tends to move toward x-direction (local coordinate placed on crack tip). Finally, a FE simulation is performed to numerically determine SIFs.
Recent advances of crack propagation in human bone Craciun, EM; Cergan, R.; Dragosloveanu, S.
Analele ştiinţifice ale Universităţii "Ovidius" Constanţa. Seria Matematică,
06/2024, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Recent results in mathematical modeling predicting crack behavior under various load conditions in human bones as anisotropic elastic composite materials are presented in this survey. New and ...interesting challenges in theoretical models of fracture were proposed and had significant importance for fracture mechanics. Our goal is to present an overview of the use and limitations of existing relevant theories. The present study aims to introduce mathematical models to researchers unfamiliar with the concepts, to improve and provide new insights into bone fracture mechanics.
Based on multiteam system (MTS) theory and creativity theory, this study explores the influencing factor model of multiteam digital creativity (MTDC) in the action phase through two cross-validation ...studies, filling a theoretical gap and responding to the research call. Study 1 is a qualitative analysis method to fully explore the relevant influencing factors and enhance the theoretical saturation. Study 2 is an optimized DEMATEL method, known as the CL-WG DEMATEL analysis method, which cross-validates the new theoretical model and measures the centrality of the influencing factors. This study finds that the influence factor model of MTDC has eight major factors and distributes in four different levels. Further analysis shows that the three influences (team digital ability, multiteam digital sharing, and organizational digital resource matching) with the highest centrality of impact on MTDC all belong to the collective level, which indicates the uniqueness of the action phase of the performance episodes. The two cross-validation studies enhance the scientific validity of the new theoretical exploration. In addition, Theoretical and practical implications of the results are presented, and future directions for research are discussed.
•MTS-CNN shows high detection accuracy through balanced training of crops and weeds.•We propose one-stage training method for detecting crop and weed by attention module.•The losses for crops, weeds, ...and combination of them are all separately designed.•MTS-CNN uses a two-stage segmentation of crops and weeds.•Trained MTS-CNN model and algorithm are made publicly available via GitHub.
Research is being extensively conducted on using deep learning in the field of crop and weed segmentation based on images captured with a camera. However, the segmentation performance for various crops and weeds varies significantly, implying that certain classes of crops or weeds are not being detected properly. This problem may also occur in the loss calculations used in crop and weed segmentation. In previous studies, the cross-entropy loss (corresponding to a distribution loss) and dice loss (using spatial information) have been widely used. However, such losses lead to large discrepancies in crop and weed segmentation performance, as the correlations between crop and weed classes are not considered. In order to solve these problems, this study proposes multi-task semantic segmentation-convolutional neural network for detecting crops and weeds (MTS-CNN) using one-stage training. This approach adds the crop, weed, and both (crop and weed) losses to heighten the correlations between the crop and weed classes, and designs the model so that the object (crop and weed) region is trained intensively. In experiments conducted using three types of open databases - the BoniRob dataset, a crop/weed field image dataset (CWFID), and rice seedling and weed dataset - the mean intersection of union (MIOU) values of the segmentation for the crops and weeds in the MTS-CNN are 0.9164, 0.8372, and 0.8260, respectively. Thus, the results indicate higher accuracy from the proposed approach than from the state-of-the-art methods.
The Pécs-Danitzpuszta sand pit is the most important outcrop of the oldest Pannonian (upper Miocene, Tortonian) deposits in southern Hungary. A trench excavated in 2018 exposed Lake Pannon deposits ...and underlying Paratethys strata down to the upper Badenian (Serravallian), and together with the sand pit they make up a continuous sedimentary succession with a true thickness of ~220 metres. Due to tectonic deformation, middle Miocene deposits and carbonates in the lowermost Pannonian are overturned. Layers become vertical close to the marl-sand boundary, then the dip changes to normal, with continuously decreasing dip angles. The exposed succession starts with 5 m of upper Badenian (13.8-12.6 Ma old) calcareous marls and sandy limestones with sublittoral, then littoral molluscs, which were deposited in the normal salinity seawaters of the Central Paratethys. The overlying 8 m of sand, silt, sandy breccia and conglomerate are fossil-free,; only the lowermost silt layer contains reworked Badenian microfauna. This unit probably accumulated from gravity-driven flows in a fan-like, probably terrestrial depositional setting. The next 7.5 m of frequently alternating thin-bedded limestones, marls and clays with sublittoral biota represent rapid transgression. Foraminifers, ostracods, molluscs and calcareous nannoplankton indicate late Sarmatian, then Pannonian age for this interval. However, the locations of the boundaries indicated by the various groups are not are not consistent, making the position of the Sarmatian/Pannonian boundary uncertain. The Sarmatian beds with marine fossils still accumulated in the Paratethys, between ~12.1–11.6 Ma, under varying salinities due among others to temporary freshwater input. The Pannonian strata already represent sediments of the brackish Lake Pannon. Above these beds, uniform calcareous marl becomes dominant with some clay layers and graded or structureless conglomerate to sandstone interbeds. The deposition of the overall 64- m- thick Pannonian calcareous marl section took place in the open, probably few -hundred -metres -deep water of the lake between ~11.62 and 10.5–10.2 Ma. It may represent a rare, well-exposed surface occurrence of the Endrőd Formation which is known from thousands of wells in the Pannonian Basin. Above this section, a 6-7 -m- thick transitional interval of silty marls and sands is followed by ~140 m of limonitic, pebbly sands. They have poor to moderate sorting and rounding, metre -thick beds with transitional boundaries and abundant fossils and clasts reworked from older Miocene units. Their accumulation took place between 10.2-10.5 and 9.6 Ma by gravity flows connected to deep-water portions of fan deltas.
Floods are among the most dangerous geohazards in Central Europe. Their occurrence is often the result of the cumulative contribution of sub-catchments in the culmination zone of a mountain range, ...which subsequently has a devastating effect in the foreland. However, data on discharges from gauging stations are mostly missing from these sites (high-gradient streams), which are crucial to understanding the origin of floods in low-lying populated areas where they can cause significant damage. Therefore, this study focuses on an extensive reconstruction of flood events in 13 sub-catchments in the culmination zone of the Orlicke hory Mts. Flood events were reconstructed using dendrogeomorphic approaches, currently the most accurate absolute dating method. The analysis revealed 111 floods in all sub-catchments during the 34 to 84 year period by dating 844 growth disturbances in a tree-ring series of 632 trees (Picea abies (L.) Karst.) damaged during the floods. Regional reconstruction across the mountain range revealed events of regional and local significance, with no direct link between event magnitude and areal extent. This is consistent with the two dominant rainfall patterns identified that likely triggered the floods (short-term extreme rainfall and medium-term above-average rainfall). In particular, however, the study revealed several patterns of spatial transformation of flood events from source sub-catchments to their form captured at gauging stations in the foreland. The combination of various lines of evidence (geomorphic mapping, growth disturbance patterns, spatial pattern of flooding) suggests a limited erosional effect of most of the reconstructed events. The findings thus shed new light on the overall dynamics of floods in the mountain massif and their impact on flood discharges in the foreland.
Display omitted
•A floods chronology was compiled from 13 sub-catchments in the Orlicke hory Mts.•111 flood events were dated using data from 632 disturbed trees.•Short-term extreme and medium-term above-average precipitation are the main triggers.•Patterns of flood transformation from source watersheds to forefields were revealed.
With the intelligentization of Maritime Transportation System (MTS), Internet of Thing (IoT) and machine learning technologies have been widely used to achieve the intelligent control and routing ...planning for ships. As an important branch of machine learning, federated learning is the first choice to train an accurate joint model without sharing ships' data directly. However, there are still many unsolved challenges while using federated learning in IoT-enabled MTS, such as the privacy preservation and Byzantine attacks. To surmount the above challenges, a novel mechanism, namely DisBezant, is designed to achieve the secure and Byzantine-robust federated learning in IoT-enabled MTS. Specifically, a credibility-based mechanism is proposed to resist the Byzantine attack in non-iid (not independent and identically distributed) dataset which is usually gathered from heterogeneous ships. The credibility is introduced to measure the trustworthiness of uploaded knowledge from ships and is updated based on their shared information in each epoch. Then, we design an efficient privacy-preserving gradient aggregation protocol based on a secure two-party calculation protocol. With the help of a central server, we can accurately recognise the Byzantine attackers and update the global model parameters privately. Furthermore, we theoretically discussed the privacy preservation and efficiency of DisBezant. To verify the effectiveness of our DisBezant, we evaluate it over three real datasets and the results demonstrate that DisBezant can efficiently and effectively achieve the Byzantine-robust federated learning. Although there are 40% nodes are Byzantine attackers in participants, our DisBezant can still recognise them and ensure the accurate model training.
•The mixed-mode fracture behavior of rock-type U-notched specimens is studied experimentally and theoretically.•The Brazilian disk weakened by the central U-notches were tested under mixed mode I/II ...loading.•Based on the maximum tangential stress (MTS) criterion, a new simple approach (MTS-FEM) is suggested to predict the fracture resistance of U-notched samples.•The tangential stress component at critical distance from the notch border is obtained from finite element analysis in the MTS-FEM criterion.•The value of the critical distance in MTS-FEM is determined corresponding to the fracture toughness for any arbitrary U-notched sample.•It is shown that the MTS-FEM criterion is able to estimate the fracture resistance of U-notched rock samples very well.
The aim of this paper is to present a new approach for predicting the mixed-mode fracture resistance of rock-type specimens containing U-shaped notches. The new approach is a modified form of maximum tangential stress (MTS) criterion which states the fracture takes place when the maximum tangential stress at the critical distance from the notch border attains critical value. The critical distance in rock-type specimen is relatively large and the formulations presented in the conventional MTS for characterizing the tangential stress component cannot provide good estimates. Therefore, the modified MTS (MTS-FEM) criterion proposes that the value of maximum tangential stress at the critical distance is determined directly from finite element analysis. Several mixed-mode fracture tests were conducted on the Brazilian disks weakened by central U notches in order to evaluate the MTS-FEM criterion. The comparison between the fracture loads obtained from experiments and those predicted by the MTS-FEM criterion shows that the MTS-FEM criterion can provide good estimates for fracture loads of rock-type U-notched samples under mixed mode loading.
PDF
