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Mikov, A. I. "Connectivity of dynamic graphs in multiply connected spaces". Informatization and communication, n.º 2 (30 de abril de 2020): 108–13. http://dx.doi.org/10.34219/2078-8320-2020-11-2-108-113.
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Dynamic geometric graphs are natural mathematical models of many real-world systems placed and moving in space: computer ad hoc networks, transport systems, territorial distributed systems for various purposes. An important property of such graphs is connectivity, which is difficult to maintain during movement due to the presence of obstacles on the ground. In this paper, a model of a multiply connected region with obstacles of the “city blocks” type is constructed and the behavior of the characteristics of dynamic graphs located in such domains is studied. A probabilistic approach to the study of graphs is proposed, in which their characteristics are considered as random processes. For graphs of different scales, dependences of the connectivity probability, the number of components on the parameters of a multiply connected region, and the radius of stable signal reception / transmission were found. The mathematical expectation of the number of components in the starting random geometric graph is found. The significant influence not only of geometrical parameters, but also of the topological characteristics of a multiply-connected domain has been revealed. Graphs of changes in the probability of connectedness of a dynamic graph over time are constructed on the basis of calculating the average value over the set of realizations of the random process of moving network nodes. They are characterized by a periodic component that correlates with the structure of a multiply connected region, and a component that exponentially decreases with time. The dependence of the probability of connectedness of the graph on the direction of the network displacement vector was studied, which turned out to be very significant. The results obtained give an idea of the influence of a multiply-connected domain on the dynamics of graphs, and can be used in control algorithms for mobile distributed systems to ensure their spatial connectivity.
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Zhang, Qi, Jianlong Chang, Gaofeng Meng, Shiming Xiang y Chunhong Pan. "Spatio-Temporal Graph Structure Learning for Traffic Forecasting". Proceedings of the AAAI Conference on Artificial Intelligence 34, n.º 01 (3 de abril de 2020): 1177–85. http://dx.doi.org/10.1609/aaai.v34i01.5470.
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As an indispensable part in Intelligent Traffic System (ITS), the task of traffic forecasting inherently subjects to the following three challenging aspects. First, traffic data are physically associated with road networks, and thus should be formatted as traffic graphs rather than regular grid-like tensors. Second, traffic data render strong spatial dependence, which implies that the nodes in the traffic graphs usually have complex and dynamic relationships between each other. Third, traffic data demonstrate strong temporal dependence, which is crucial for traffic time series modeling. To address these issues, we propose a novel framework named Structure Learning Convolution (SLC) that enables to extend the traditional convolutional neural network (CNN) to graph domains and learn the graph structure for traffic forecasting. Technically, SLC explicitly models the structure information into the convolutional operation. Under this framework, various non-Euclidean CNN methods can be considered as particular instances of our formulation, yielding a flexible mechanism for learning on the graph. Along this technical line, two SLC modules are proposed to capture the global and local structures respectively and they are integrated to construct an end-to-end network for traffic forecasting. Additionally, in this process, Pseudo three Dimensional convolution (P3D) networks are combined with SLC to capture the temporal dependencies in traffic data. Extensively comparative experiments on six real-world datasets demonstrate our proposed approach significantly outperforms the state-of-the-art ones.
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Jha, Lipika y K. S. Patnaik. "A New Method to Compute Dynamic Slicing using Program Dependence Graph". International Journal of Computer Applications 75, n.º 13 (23 de agosto de 2013): 30–36. http://dx.doi.org/10.5120/13173-0852.
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Deptuła, Adam, Józef Drewniak y Marian A. Partyka. "Analysis of a planetary gear modeled with a contour graph taking into account the method of parametric play structures". Mechanik 90, n.º 7 (10 de julio de 2017): 640–42. http://dx.doi.org/10.17814/mechanik.2017.7.98.
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Previous applications of the graph theory concerned the modeling of gears for dynamic analysis, kinematic analysis, synthesis, structural analysis, gearshift optimization and automatic design based on so-called graph grammars. Some tasks can be performed only by using methods resulting from a graph theory, e.g. enumeration of structural solutions. The contour plot method consists in distinguishing a series of consecutive rigid units of the mechanism, forming a closed loop (so-called contour). At a later stage, it is possible to analyze the obtained contour graph as a directed graph of dependence. The work presents an example of the use of game-tree structures for describing the contour graph of a planetary gear. As a result of the decomposition of the graph in the dependence on each of the vertices, game-tree structures are obtained, which allow calculate algorithmically.
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DEPTUŁA, Adam y Marian PARTYKA. "SIMILARITIES AND DIFFERENCES OF COMPLEX PARAMETRIC GAME TREES FOR INVESTIGATIONS OF DYNAMIC PROPERTIES OF MACHINE SYSTEMS". Scientific Journal of the Military University of Land Forces 165, n.º 3 (1 de julio de 2012): 314–25. http://dx.doi.org/10.5604/01.3001.0002.3506.
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The paper concerns the application of dependence graphs and game tree-structures for the analysis and synthesis of the dynamic properties of machine systems. Graph distributions starting from various beginning vertices are presented in this paper. In order to illustrate the acceptable subsystems of parent machine system, similarities and differences between complex parametric trees are also given. It is also possible to find the part common to all the game tree-structures and describe it over separate design or operational parameters.
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Xia, Tong, Junjie Lin, Yong Li, Jie Feng, Pan Hui, Funing Sun, Diansheng Guo y Depeng Jin. "3DGCN: 3-Dimensional Dynamic Graph Convolutional Network for Citywide Crowd Flow Prediction". ACM Transactions on Knowledge Discovery from Data 15, n.º 6 (28 de junio de 2021): 1–21. http://dx.doi.org/10.1145/3451394.
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Crowd flow prediction is an essential task benefiting a wide range of applications for the transportation system and public safety. However, it is a challenging problem due to the complex spatio-temporal dependence and the complicated impact of urban structure on the crowd flow patterns. In this article, we propose a novel framework, 3- D imensional G raph C onvolution N etwork (3DGCN), to predict citywide crowd flow. We first model it as a dynamic spatio-temporal graph prediction problem, where each node represents a region with time-varying flows, and each edge represents the origin–destination (OD) flow between its corresponding regions. As such, OD flows among regions are treated as a proxy for the spatial interactions among regions. To tackle the complex spatio-temporal dependence, our proposed 3DGCN can model the correlation among graph spatial and temporal neighbors simultaneously. To learn and incorporate urban structures in crowd flow prediction, we design the GCN aggregator to be learned from both crowd flow prediction and region function inference at the same time. Extensive experiments with real-world datasets in two cities demonstrate that our model outperforms state-of-the-art baselines by 9.6%∼19.5% for the next-time-interval prediction.
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DJAMEGNI, CLÉMENTIN TAYOU y MAURICE TCHUENTE. "A NEW ALGORITHM FOR DYNAMIC PROGRAMMING ON REGULAR ARRAYS". Parallel Processing Letters 10, n.º 01 (marzo de 2000): 15–27. http://dx.doi.org/10.1142/s0129626400000044.
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Given the real entries w(i, j), 1≤ i < j ≤n, and c(i, i+1), 1≤ i< n, the dynamic programming problem studied here consists of computing the coefficients c ( i , j )= w ( i , j ) + min i < k < j { c ( i , k )+ c ( k , j )}, for 1≤ i< j≤n. We show that this problem can be solved in optimal time T*=2n-1 on a regular array of size n 2/10+ O ( n ). The number of processors required by this new algorithm improves the best previously known bound n 2/10+ O ( n ). The idea introduced here is to apply to the dependence graph associated with the problem a pre-processing that removes long-range communications in order to obtain a new locally connected graph which is suitable for the application of powerful allocation techniques.
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Zhang, Yihe, Sheng Zhang, Jaime S. Ide, Sien Hu, Simon Zhornitsky, Wuyi Wang, Guozhao Dong, Xiaoying Tang y Chiang-shan R. Li. "Dynamic network dysfunction in cocaine dependence: Graph theoretical metrics and stop signal reaction time". NeuroImage: Clinical 18 (2018): 793–801. http://dx.doi.org/10.1016/j.nicl.2018.03.016.
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Alhasan, Abu Mohamed. "Spatiotemporal Graph Imaging Associated with Multilevel Atomic Excitations". Proceedings 67, n.º 1 (11 de noviembre de 2020): 16. http://dx.doi.org/10.3390/asec2020-07886.
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In this paper, we establish a graph imaging technique to manifest local stabilization within atomic systems of multiple levels. Specifically, we address the interrelation between local stabilization and image entropy. As an example, we consider the mutual interaction of two pair of pulses propagating in a double-Λ configuration. Thus, we have two different sets of two pulses that share the same shape and phase, initially. The first (second) set belongs to lower (upper) -Λ subsystems, respectively. The configuration of two pair of pulses is considered as a dynamical graph model with four nodes. The dynamic transition matrix describes the connectivity matrix in the static graph model. It is to be emphasized that the graph and its image have the same transition matrix. In particular, the graph model exposes the stabilization in terms of the singular-value decomposition of energies for the transition matrix, that is, irrespectively of the structure of the transition matrix. The image model of the graph displays the details of the matrix structure in terms of row and column probabilities. Therefore, it enables one to study conditional probabilities and mutual information inherent in the network of the graph. Furthermore, the graph imaging provides the main row/column contribution to the transition matrix in terms of image entropy. Our results show that image entropy exposes spatial dependence, which is irrelevant to graph entropy.
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Belaid, Ikbel, Fabrice Muller y Maher Benjemaa. "Static Scheduling of Periodic Hardware Tasks with Precedence and Deadline Constraints on Reconfigurable Hardware Devices". International Journal of Reconfigurable Computing 2011 (2011): 1–28. http://dx.doi.org/10.1155/2011/591983.
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Task graph scheduling for reconfigurable hardware devices can be defined as finding a schedule for a set of periodic tasks with precedence, dependence, and deadline constraints as well as their optimal allocations on the available heterogeneous hardware resources. This paper proposes a new methodology comprising three main stages. Using these three main stages, dynamic partial reconfiguration and mixed integer programming, pipelined scheduling and efficient placement are achieved and enable parallel computing of the task graph on the reconfigurable devices by optimizing placement/scheduling quality. Experiments on an application of heterogeneous hardware tasks demonstrate an improvement of resource utilization of 12.45% of the available reconfigurable resources corresponding to a resource gain of 17.3% compared to a static design. The configuration overhead is reduced to 2% of the total running time. Due to pipelined scheduling, the task graph spanning is minimized by 4% compared to sequential execution of the graph.
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Hansknecht, Christoph, Imke Joormann y Sebastian Stiller. "Dynamic Shortest Paths Methods for the Time-Dependent TSP". Algorithms 14, n.º 1 (12 de enero de 2021): 21. http://dx.doi.org/10.3390/a14010021.
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The time-dependent traveling salesman problem (TDTSP) asks for a shortest Hamiltonian tour in a directed graph where (asymmetric) arc-costs depend on the time the arc is entered. With traffic data abundantly available, methods to optimize routes with respect to time-dependent travel times are widely desired. This holds in particular for the traveling salesman problem, which is a corner stone of logistic planning. In this paper, we devise column-generation-based IP methods to solve the TDTSP in full generality, both for arc- and path-based formulations. The algorithmic key is a time-dependent shortest path problem, which arises from the pricing problem of the column generation and is of independent interest—namely, to find paths in a time-expanded graph that are acyclic in the underlying (non-expanded) graph. As this problem is computationally too costly, we price over the set of paths that contain no cycles of length k. In addition, we devise—tailored for the TDTSP—several families of valid inequalities, primal heuristics, a propagation method, and a branching rule. Combining these with the time-dependent shortest path pricing we provide—to our knowledge—the first elaborate method to solve the TDTSP in general and with fully general time-dependence. We also provide for results on complexity and approximability of the TDTSP. In computational experiments on randomly generated instances, we are able to solve the large majority of small instances (20 nodes) to optimality, while closing about two thirds of the remaining gap of the large instances (40 nodes) after one hour of computation.
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Revotjuk, M. P., N. V. Khajynova, A. P. Kuznetsov y L. Y. Shilin. "Dynamic asymmetric assignment problem in open multi-agent systems". Doklady BGUIR 18, n.º 5 (2 de septiembre de 2020): 53–61. http://dx.doi.org/10.35596/1729-7648-2020-18-5-53-61.
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The purpose of the work is to develop models and algorithms for optimizing matching in dynamically generated graphs of asymmetric relations in coordinated open systems of interacting agents with centralized and collective control. The dynamic asymmetric matching optimization problem arises here as a result of a compromise approximation of the mapping of the dynamic programming method onto a stream of known open assignment problems or several traveling salesmen. However, the branching alternatives presented in this way for independent tasks do not take into account the interdependence of real relationships between agents and their tasks, including their relationship to time. Ignoring the dependence of branching alternatives leads to a delay in the moment or to a loss in the quality of assignment of tasks to coordinated agents. The main idea of the proposed implementation of the principle known for effective control is to postpone the moment the final decision is made to the latest moment, taking into account the susceptibility of the system to local changes in state variables. The interdependence of states is revealed on the basis of the analysis of the correspondence of the graph of the current matching with the optimal solution on the subgraph of perfect matching. The transition between states is implemented by the incremental version of the reoptimization algorithm for solving linear problems of assigning the shortest replenishing path using the method. The space of search states is a dynamically generated bipartite sparse graph of alternatives for a combination of agents and tasks, represented by a list of arcs. To highlight the sets of changed arcs, it is proposed to supplement the weight of the arcs with the boundaries of the stability intervals of the solution, optionally formed in the background. By default, the weight of the modified arc matches the boundary of the stability interval. On each correction cycle of the lists of agents, tasks, and their associations, subsets of elements are selected for which reconsideration of matching is required. An enhanced condition for the selection of such elements is to go beyond the boundaries of the stability interval. In this case, the asymmetry of the assignment problem is taken into account by choosing the adjacency structure for the fraction of the graph with a minimum of vertices. As a result, the reaction time of procedures for solving the assignment problem is reduced by an order of magnitude.
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Kozlova, Mariia y Vitaly Shamansky. "Using dynamic graphs on the example of calculating the temperature field of a lead-acid battery". E3S Web of Conferences 289 (2021): 06002. http://dx.doi.org/10.1051/e3sconf/202128906002.
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This paper presents materials for modeling heat transfer in a lead-acid battery in its operating mode. The approach for modeling was based on the representation of the system under study in the form of a flow graph. This approach made it possible to create a model of a battery taking into account the chemical and physical aspects of its operation and can be supplemented with other properties of the system under study, if necessary. Calculations of the temperature dependence were carried out for a daily load and in charge and discharge modes.
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Hu, Zeyuan y Eung-Joo Lee. "Dual Attention-Guided Multiscale Dynamic Aggregate Graph Convolutional Networks for Skeleton-Based Human Action Recognition". Symmetry 12, n.º 10 (24 de septiembre de 2020): 1589. http://dx.doi.org/10.3390/sym12101589.
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Traditional convolution neural networks have achieved great success in human action recognition. However, it is challenging to establish effective associations between different human bone nodes to capture detailed information. In this paper, we propose a dual attention-guided multiscale dynamic aggregate graph convolution neural network (DAG-GCN) for skeleton-based human action recognition. Our goal is to explore the best correlation and determine high-level semantic features. First, a multiscale dynamic aggregate GCN module is used to capture important semantic information and to establish dependence relationships for different bone nodes. Second, the higher level semantic feature is further refined, and the semantic relevance is emphasized through a dual attention guidance module. In addition, we exploit the relationship of joints hierarchically and the spatial temporal correlations through two modules. Experiments with the DAG-GCN method result in good performance on the NTU-60-RGB+D and NTU-120-RGB+D datasets. The accuracy is 95.76% and 90.01%, respectively, for the cross (X)-View and X-Subon the NTU60dataset.
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Sahu, Madhusmita. "Conditioned Slicing of Interprocedural Programs". International Journal of Rough Sets and Data Analysis 6, n.º 1 (enero de 2019): 43–60. http://dx.doi.org/10.4018/ijrsda.2019010103.
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Program slicing is a technique to decompose programs depending on control flow and data flow amongst several lines of code in a program. Conditioned slicing is a generalization of static slicing and dynamic slicing. A variable, the desired program point, and a condition of interest form a slicing criterion for conditioned slicing. This paper proposes an approach to calculate conditioned slices for programs containing multiple procedures. The approach is termed Node-Marking Conditioned Slicing (NMCS) algorithm. In this approach, first and foremost step is to build an intermediate symbolization of a given program code and the next step is to develop an algorithm for finding out conditioned slices. The dependence graph, termed System Dependence Graph (SDG), is used to symbolize intermediate presentation. After constructing SDG, the NMCS algorithm chooses nodes that satisfy a given condition by the process of marking and unmarking. The algorithm also finds out conditioned slices for every variable at every statement during the process. NMCS algorithm employs a stack to save call context of a method. Few edges in SDG are labeled to identify the statement that calls a method. The proposed algorithm is implemented, and its performance is tested with several case study projects.
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Ugol’nikov, O., B. Demianchuk, N. Kolesnychenko y O. Malinovsky. "EXACT SOLUTION OF TASKS OF DYNAMIC MODELING OF PROCESSES IN SYSTEMS OF TRANSPORT LOGISTIC". Collection of scientific works of Odesa Military Academy 2, n.º 12 (27 de diciembre de 2019): 5–13. http://dx.doi.org/10.37129/2313-7509.2019.12.2.5-13.
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The dynamic models of processes in transport logistics systems are considered. In the literature, such complex systems as the military transport logistics system or the combat vehicle support system are often modeled as a set of typical system states. These states are interconnected by a large number of transitions of a given intensity, which are carried out with given probabilities. Graphically, this is represented using the so-called graph of states and transitions, and the probabilities of the system being in a particular state are the subject of research in such a graph. The methods available in the literature for studying the dynamic characteristics of state graphs and transitions are analyzed. A description of the changes in probabilities as a function of time is made using systems of differential equations, usually linear. Based on practical requirements, approximate solutions to such systems are usually sought. One of the approximate methods is the decomposition method, in which, instead of a system of coupled equations, a set of independent equations is considered, the solution of which is not difficult. The results of the solution have an accuracy satisfactory from the point of view of practical use. The assumptions based on which the decomposition method can be used are analyzed. It is shown that the accuracy of the obtained results substantially depends on the given initial conditions and should increase over time, when this dependence weakens. A method is proposed for the exact solution of a system of differential equations, free of any assumptions. The use of operational calculus is substantiated, which reduces the solution of a system of linear differential equations to the solution of a system of linear algebraic equations for unknown images of the sought-for Laplace functions. The method is used to describe the process of technical support for the restoration of the transport flow of military logistics. The boundaries of the possibility of applying the results of a simpler approximate solution are established.
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Prikhodko, Ivan V. y Georgy Th Guria. "Dynamic Effects in Nucleation of Receptor Clusters". Entropy 23, n.º 10 (24 de septiembre de 2021): 1245. http://dx.doi.org/10.3390/e23101245.
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Nucleation theory has been widely applied for the interpretation of critical phenomena in nonequilibrium systems. Ligand-induced receptor clustering is a critical step of cellular activation. Receptor clusters on the cell surface are treated from the nucleation theory point of view. The authors propose that the redistribution of energy over the degrees of freedom is crucial for forming each new bond in the growing cluster. The expression for a kinetic barrier for new bond formation in a cluster was obtained. The shape of critical receptor clusters seems to be very important for the clustering on the cell surface. The von Neumann entropy of the graph of bonds is used to determine the influence of the cluster shape on the kinetic barrier. Numerical studies were carried out to assess the dependence of the barrier on the size of the cluster. The asymptotic expression, reflecting the conditions necessary for the formation of receptor clusters, was obtained. Several dynamic effects were found. A slight increase of the ligand mass has been shown to significantly accelerate the nucleation of receptor clusters. The possible meaning of the obtained results for medical applications is discussed.
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Xu, Mengyu, Xiaohui Chen y Wei Biao Wu. "Estimation of Dynamic Networks for High-Dimensional Nonstationary Time Series". Entropy 22, n.º 1 (31 de diciembre de 2019): 55. http://dx.doi.org/10.3390/e22010055.
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This paper is concerned with the estimation of time-varying networks for high-dimensional nonstationary time series. Two types of dynamic behaviors are considered: structural breaks (i.e., abrupt change points) and smooth changes. To simultaneously handle these two types of time-varying features, a two-step approach is proposed: multiple change point locations are first identified on the basis of comparing the difference between the localized averages on sample covariance matrices, and then graph supports are recovered on the basis of a kernelized time-varying constrained L 1 -minimization for inverse matrix estimation (CLIME) estimator on each segment. We derive the rates of convergence for estimating the change points and precision matrices under mild moment and dependence conditions. In particular, we show that this two-step approach is consistent in estimating the change points and the piecewise smooth precision matrix function, under a certain high-dimensional scaling limit. The method is applied to the analysis of network structure of the S&P 500 index between 2003 and 2008.
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Kovaleva, Ella A. y Mikhail Yu Dolomatov. "DEPENDENCE OF DYNAMIC VISCOSITY OF NAPHTHENIC HYDROCARBONS IN CYCLOPENTANE SERIES ON QUANTUM AND STRUCTURAL PARAMETERS". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, n.º 4 (16 de abril de 2020): 34–41. http://dx.doi.org/10.6060/ivkkt.20206304.6099.
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Interrelation of parameters for Newtonian fluid viscous flow of monocyclic hydrocarbons with quantum and structural (topological) characteristics of molecules are considered. Ionization potentials and topological indices, respectively, were considered as quantum and topological characteristics. The vertical ionization potentials were calculated by the Koopmans ' theorem of quantum chemical methods with full molecular geometry optimization. We have studied topological indices that take into account the size and shape of the molecular graph. As a topological descriptors the Wiener index, the Balaban centric index, the Randic index (the index of molecular connectivity), Gutman (Szeged) index, Platt index and the Harary index were considered. For hydrocarbons in cyclopentane series with side chains, the kinetic compensation effect of dynamic viscosity has been established, which connects the activation energy and Arrhenius factor in the framework of the Frenkel-Eyring model. It is established that for compounds of a number of five-membered naphthenes, the apparent activation energy for viscous flow and the associated pre-exponential factor, depends on quantum parameters (ionization potentials) and the topology of the molecules. In this paper, a regression quantitative structure−property relationship (QSPR) is proposed using as descriptors the ionization potentials and topological indices for the prediction of dynamic viscosity. Prognostics capabilities of the proposed model and the adequacy of the forecast were verified by calculating the values of the dynamic viscosity of hydrocarbons that are not included in the base series. Experimental and theoretical substantiation of the proposed regularity was given within the framework of the representation of the viscous flow activation energy as a measure of intermolecular interaction and the predominance of dispersion interaction in hydrocarbon molecules for cyclopentane series. The equation obtained during the study can be used to predict the viscosity characteristics of synthesized and natural five-membered naphthenes.
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Sun, Yan, Yixin Shen y Liyan Ma. "MSST-RT: Multi-Stream Spatial-Temporal Relative Transformer for Skeleton-Based Action Recognition". Sensors 21, n.º 16 (7 de agosto de 2021): 5339. http://dx.doi.org/10.3390/s21165339.
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Skeleton-based human action recognition has made great progress, especially with the development of a graph convolution network (GCN). The most important work is ST-GCN, which automatically learns both spatial and temporal patterns from skeleton sequences. However, this method still has some imperfections: only short-range correlations are appreciated, due to the limited receptive field of graph convolution. However, long-range dependence is essential for recognizing human action. In this work, we propose the use of a spatial-temporal relative transformer (ST-RT) to overcome these defects. Through introducing relay nodes, ST-RT avoids the transformer architecture, breaking the inherent skeleton topology in spatial and the order of skeleton sequence in temporal dimensions. Furthermore, we mine the dynamic information contained in motion at different scales. Finally, four ST-RTs, which extract spatial-temporal features from four kinds of skeleton sequence, are fused to form the final model, multi-stream spatial-temporal relative transformer (MSST-RT), to enhance performance. Extensive experiments evaluate the proposed methods on three benchmarks for skeleton-based action recognition: NTU RGB+D, NTU RGB+D 120 and UAV-Human. The results demonstrate that MSST-RT is on par with SOTA in terms of performance.
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Sun, Weiwei, Yufei Chen, Xiaojun Wan y Meichun Liu. "Parsing Chinese Sentences with Grammatical Relations". Computational Linguistics 45, n.º 1 (marzo de 2019): 95–136. http://dx.doi.org/10.1162/coli_a_00343.
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We report our work on building linguistic resources and data-driven parsers in the grammatical relation (GR) analysis for Mandarin Chinese. Chinese, as an analytic language, encodes grammatical information in a highly configurational rather than morphological way. Accordingly, it is possible and reasonable to represent almost all grammatical relations as bilexical dependencies. In this work, we propose to represent grammatical information using general directed dependency graphs. Both only-local and rich long-distance dependencies are explicitly represented. To create high-quality annotations, we take advantage of an existing TreeBank, namely, Chinese TreeBank (CTB), which is grounded on the Government and Binding theory. We define a set of linguistic rules to explore CTB’s implicit phrase structural information and build deep dependency graphs. The reliability of this linguistically motivated GR extraction procedure is highlighted by manual evaluation. Based on the converted corpus, data-driven, including graph- and transition-based, models are explored for Chinese GR parsing. For graph-based parsing, a new perspective, graph merging, is proposed for building flexible dependency graphs: constructing complex graphs via constructing simple subgraphs. Two key problems are discussed in this perspective: (1) how to decompose a complex graph into simple subgraphs, and (2) how to combine subgraphs into a coherent complex graph. For transition-based parsing, we introduce a neural parser based on a list-based transition system. We also discuss several other key problems, including dynamic oracle and beam search for neural transition-based parsing. Evaluation gauges how successful GR parsing for Chinese can be by applying data-driven models. The empirical analysis suggests several directions for future study.
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Шакало, Руслан Юрьевич, Роман Петрович Придорожный, Юрий Владимирович Якушев, Вячеслав Михайлович Меркулов y Анатолий Павлович Зиньковский. "ДЕМПФИРОВАНИЕ КОЛЕБАНИЙ ОХЛАЖДАЕМЫХ ПОПАРНО БАНДАЖИРОВАННЫХ РАБОЧИХ ЛОПАТОК ТУРБИН". Aerospace technic and technology, n.º 7 (31 de agosto de 2019): 109–13. http://dx.doi.org/10.32620/aktt.2019.7.15.
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The cooled turbine blades are the parts that determine the reliability and service life of a gas turbine engine. As is known, most cases of engine failure are related to the destruction of turbine blades. Turbine blades during operation experience high thermal stresses, the stresses from centrifugal and gas forces, as well as dynamic stresses. This paper presents methods for ensuring an acceptable level of dynamic stresses in turbine blades. One of the most effective methods is considered in more detail - pairwise shrouded cooled turbine blades. The effectiveness of the damping of such working blades depends on the guaranteed contact of the contact surfaces of the flanges of the shanks and banding shelves and the optimality of the shroud connection. As the object of the study, we chose pairwise shrouded turbine blades from the engine, on which there were several cases of destruction of the turbine blades. To assess the optimality of the bandage connection of the working blades under study, a scheme has been developed for calculating the force acting on the contact surfaces of the banding shelves. According to the developed scheme, calculations were made of the forces acting on the contact surfaces of the retaining shelves, both of the investigated working blades, and similarly pairwise shrouded cooled turbine blades, developed by SE «Ivchenko-Progress». After calculating the force acting on the contact surface of the retaining shelf, the ratio of the received force to the parameters of the feather profile, such as chord and CMAX, is calculated. According to the data obtained, a graph of the dependence of the voltage in the blade on the relative force acting on the contact surface of the retaining shelf was plotted. The analysis of the obtained graph made it possible to conclude that there is an optimal force at which dynamic stresses will be acceptable. However, since a small sample of pairwise shrouded cooled turbine blades is presented, it is necessary to continue the work on determining the criteria for optimality of the shroud linkage and on clarifying the resulting relationship.
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Poddaeva, Olga, Anastasia Fedosova y Julia Gribach. "The study of wind effects on the bridge constructions". E3S Web of Conferences 97 (2019): 03030. http://dx.doi.org/10.1051/e3sconf/20199703030.
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Construction of bridge structures occupies one of the leading positions in the construction industry. However, the design of these objects is a complex multi-factor task. Particular attention in the development of bridge structures must be paid to wind loads, since their dynamic loads can cause a number of adverse aeroelastic reactions. Large-scale bridge structures, which are flexible structures, are more susceptible to horizontal influence of the wind. This article presents a description of the study of wind impact on a bridge being built in the city of Moscow, according to a technique that was developed by employees of the UNPL AAISK (NRU MGSU). In this case, a test of the span section of the model on a specialized stand was conducted. The example of this object shows a graph of the dependence of the amplitude of oscillations of the bridge span on the wind speed without the use of fairings and their installation. According to the results of the work conclusions.
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Kozlovskaya, Olga Viktorovna y Yuliya Vitalevna Belyaeva. "Rare component as an indicator of human flora transformation". Samara Journal of Science 6, n.º 1 (1 de marzo de 2017): 37–41. http://dx.doi.org/10.17816/snv201761107.
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This paper discusses the use of the rare flora component of Melekessky-Stavropol landscaped area as an indicator of anthropogenic transformation. The paper contains an ecological-floristic zoning of Melekessky-Stavropol landscaped area (lowland Trans-Volga) and the value of anthropogenic stress factors for each elementary floristic subarea and for the landscape area as a whole. The factors value due to non-equivalent sub-areas and lack of research is formalized and pointed. Relative factors values are compared to the total factor value for the landscape area. Rare flora component was studied and rarity species saturation was calculated, i.e. their number per unit area for each of the elementary floristic sub-areas. The authors revealed the dependence of rarity species saturation on the level of anthropogenic load in elementary subareas - the higher the rarity species saturation, the less anthropogenically transformed flora. A corresponding graph is presented and described in detail that makes it possible to estimate the anthropogenic transformation of flora, not only its active, dynamic components - alien flora, but also the degree of preservation of rare species.
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Smirnov, Andrii y Vsevolod Beihul. "Belt conveyers rollers average term of service". E3S Web of Conferences 109 (2019): 00095. http://dx.doi.org/10.1051/e3sconf/201910900095.
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The paper is proved to one of the important conveyer transport system task – to roller’s term of service (TS) determination. The task solving permit to evaluate the different designs belt conveyers reliable. The article represent the tasks of belt conveyers roller’s average TS determination were set and solved for the different types of roller supports. Dynamic efforts arised with the loading motion and caused with belt bend are principal factor for the calculation of TS rollers. The graph of dependence roller’s average TS from belt velocity for different roller’s types were obtained. Obtain analyses results permit to set: average roller TS decrease under velocity increases for all types of roller’s, TS for dumping overhead roller supports and damping roller supports is substantially greater, then for hard and overhead roller supports. In addition, at some values of the belt velocity TS service can sharply decrease for all types of roller supports. It takes place in resonances related to vibrations of belt at motion of large pieces of load. Achieved results may be applied in mining, metallurgical and building industry.
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Zou, Xiangyu, Jinjin Zhao, Duan Zhao, Bin Sun, Yongxin He y Stelios Fuentes. "Air Quality Prediction Based on a Spatiotemporal Attention Mechanism". Mobile Information Systems 2021 (19 de febrero de 2021): 1–12. http://dx.doi.org/10.1155/2021/6630944.
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With the rapid development of the Internet of Things and Big Data, smart cities have received increasing attention. Predicting air quality accurately and efficiently is an important part of building a smart city. However, air quality prediction is very challenging because it is affected by many complex factors, such as dynamic spatial correlation between air quality detection sensors, dynamic temporal correlation, and external factors (such as road networks and points of interest). Therefore, this paper proposes a long short-term memory (LSTM) air quality prediction model based on a spatiotemporal attention mechanism (STA-LSTM). The model uses an encoder-decoder structure to model spatiotemporal features. A spatial attention mechanism is introduced in the encoder to capture the relative influence of surrounding sites on the prediction area. A temporal attention mechanism is introduced in the decoder to capture the time dependence of air quality. In addition, for spatial data such as point of interest (POI) and road networks, this paper uses the LINE graph embedding method to obtain a low-dimensional vector representation of spatial data to obtain abundant spatial features. This paper evaluates STA-LSTM on the Beijing dataset, and the root mean square error (RMSE) and R-squared ( R 2 ) indicators are used to compare with six benchmarks. The experimental results show that the model proposed in this paper can achieve better performance than the performances of other benchmarks.
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Kari, Chadi, Alexander Russell y Narasimha Shashidhar. "Work-Competitive Scheduling on Task Dependency Graphs". Parallel Processing Letters 25, n.º 02 (junio de 2015): 1550001. http://dx.doi.org/10.1142/s0129626415500012.
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A fundamental problem in distributed computing is the task of cooperatively executing a given set of [Formula: see text] tasks by [Formula: see text] asynchronous processors where the communication medium is dynamic and subject to failures. Also known as do-all, this problem been studied extensively in various distributed settings. In [2], the authors consider a partitionable network scenario and analyze the competitive performance of a randomized scheduling algorithm for the case where the tasks to be completed are independent of each other. In this paper, we study a natural extension of this problem where the tasks have dependencies among them. We present a simple randomized algorithm for [Formula: see text] processors cooperating to perform [Formula: see text] known tasks where the dependencies between them are defined by a [Formula: see text]-partite task dependency graph and additionally these processors are subject to a dynamic communication medium. By virtue of the problem setting, we pursue competitive analysis where the performance of our algorithm is measured against that of the omniscient offline algorithm which has complete knowledge of the dynamics of the communication medium. We show that the competitive ratio of our algorithm is tight and depends on the dynamics of the communication medium viz. the computational width defined in [2] and also on the number of partitions of the task dependency graph.
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Smirnov, A. I. y J. E. Shklyarskiy. "Adaptive current protection in electrical complexes with small power plants". E3S Web of Conferences 266 (2021): 04002. http://dx.doi.org/10.1051/e3sconf/202126604002.
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The article considers electrical complexes with power plants of small capacity. The influence of power generation sources on short-circuit current distribution has been investigated. Reduced sensitivity of back-up current protection and dependence of current distribution on power plant capacity are revealed. Recommendations for minimizing false operation of short-circuit protection in networks with distributed power generation are proposed. An algorithm for adaptive current protection, which uses graph theory to determine the stages of selectivity of relay protection based on finding the shortest Dijkstra path and calculation of equivalent resistance in networks with multiple sources of power generation, which provides selec-tivity and sensitivity of current protection when changing the generated power of generators and the structure of the distribution network is pre-sented. The algorithm uses communication lines with a central control unit to monitor the distribution network and update the current triggering of the relay protection in accordance with changes in the structure of the power grid. The proposed system is designed so that it can respond to dynamic changes in the structure of the network and the state of operation of power plants. Simulation modeling in the Matlab/Simulink software package was performed and the results of the algorithm are presented.
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Aledo, Juan A., Luis G. Diaz, Silvia Martinez y Jose C. Valverde. "Coexistence of Periods in Parallel and Sequential Boolean Graph Dynamical Systems over Directed Graphs". Mathematics 8, n.º 10 (16 de octubre de 2020): 1812. http://dx.doi.org/10.3390/math8101812.
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In this work, we solve the problem of the coexistence of periodic orbits in homogeneous Boolean graph dynamical systems that are induced by a maxterm or a minterm (Boolean) function, with a direct underlying dependency graph. Specifically, we show that periodic orbits of any period can coexist in both kinds of update schedules, parallel and sequential. This result contrasts with the properties of their counterparts over undirected graphs with the same evolution operators, where fixed points cannot coexist with periodic orbits of other different periods. These results complete the study of the periodic structure of homogeneous Boolean graph dynamical systems on maxterm and minterm functions.
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Chen, Cen, Kenli Li, Sin G. Teo, Xiaofeng Zou, Kang Wang, Jie Wang y Zeng Zeng. "Gated Residual Recurrent Graph Neural Networks for Traffic Prediction". Proceedings of the AAAI Conference on Artificial Intelligence 33 (17 de julio de 2019): 485–92. http://dx.doi.org/10.1609/aaai.v33i01.3301485.
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Traffic prediction is of great importance to traffic management and public safety, and very challenging as it is affected by many complex factors, such as spatial dependency of complicated road networks and temporal dynamics, and many more. The factors make traffic prediction a challenging task due to the uncertainty and complexity of traffic states. In the literature, many research works have applied deep learning methods on traffic prediction problems combining convolutional neural networks (CNNs) with recurrent neural networks (RNNs), which CNNs are utilized for spatial dependency and RNNs for temporal dynamics. However, such combinations cannot capture the connectivity and globality of traffic networks. In this paper, we first propose to adopt residual recurrent graph neural networks (Res-RGNN) that can capture graph-based spatial dependencies and temporal dynamics jointly. Due to gradient vanishing, RNNs are hard to capture periodic temporal correlations. Hence, we further propose a novel hop scheme into Res-RGNN to utilize the periodic temporal dependencies. Based on Res-RGNN and hop Res-RGNN, we finally propose a novel end-to-end multiple Res-RGNNs framework, referred to as “MRes-RGNN”, for traffic prediction. Experimental results on two traffic datasets have demonstrated that the proposed MRes-RGNN outperforms state-of-the-art methods significantly.
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ESHUIS, RIK y PAUL GREFEN. "COMPOSING SERVICES INTO STRUCTURED PROCESSES". International Journal of Cooperative Information Systems 18, n.º 02 (junio de 2009): 309–37. http://dx.doi.org/10.1142/s0218843009002026.
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Service composition languages like BPEL and many enactment tools only support structured process models, but most service composition approaches only consider unstructured process models. This paper defines an efficient algorithm that composes a set of cooperative services with their dependencies into a structured process. The algorithm takes as input a dependency graph and returns a structured process model that orchestrates the services while respecting their dependencies. The algorithm is embedded in a lightweight, semi-automated service composition approach, in which first dependencies between services are derived in a semi-automated way and next the algorithm is used to construct a structured composition. The approach has been implemented in a prototype that supports the dynamic formation and collaboration of dynamic virtual enterprises using cross-organizational service-oriented technology.
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Тretyak, V. M., V. V. Sheban, R. V. Oliadnichuk, O. F. Govorov y R. V. Melnik. "Influence of hinged device parameters on negative resonance oscillations during the operation of machine-tractor unit in transport mode". Mehanization and electrification of agricultural, n.º 12 (2020): 129–36. http://dx.doi.org/10.37204/0131-2189-2020-12-15.
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Annotation Purpose. Reducing the influence of resonance phenomena on the structural elements of a tractor of the KIY 14102 type when driving with an attached implement in transport mode. Methods. To solve this problem means of graph-analytical constructions, analytical geometry, oscillation theory and theoretical mechanics were used. Results. On the basis of the graphic-analytical analysis of the kinematic diagram of the tractor attachment of the KIY 14102 type, it was found that the position of the instantaneous center of its rotation significantly depends on the change in the angle between the tractor frame and the levers, which are united by the CA-1 automatic connection device. The frequency range of forced oscillations of the tractor frame, which occur when driving in a certain speed range, can coincide with the relative natural frequency of the tractors, which leads to resonance phenomena. Resonant longitudinal-angular vibrations of the tractor frame reduce the normal reactions of the steered wheels with the supporting surface, which worsens controllability. Changing the frequency of the natural resonance of the elements connecting the tractor with the implement can be done by changing the kinematic stiffness of the mounted system. Conclusions 1. The kinematic diagram of the hinged device of tractors significantly affects the dependence of the position of the instantaneous center of rotation of the hinged device relative to the mass of the implement that is aggregated. 2. The existing parameters of the mounted systems of tractors of the KIY 14102 type can lead to the occurrence of resonance phenomena when driving in transport mode on unpaved field roads, which negatively affects the controllability of the MTA. 3. Reducing the resonant frequency of natural vibrations of the attachment system with the tool, by reducing the kinematic stiffness, improves the dynamics of the interaction of the elements of the machine-tractor unit with each other and with the supporting surface. Keywords: machine-tractor unit, clutch system, tests, dynamic loads, strain gauge measurements, air pressure in tires.
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Kissmann, P. y J. Hoffmann. "BDD Ordering Heuristics for Classical Planning". Journal of Artificial Intelligence Research 51 (30 de diciembre de 2014): 779–804. http://dx.doi.org/10.1613/jair.4586.
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Symbolic search using binary decision diagrams (BDDs) can often save large amounts of memory due to its concise representation of state sets. A decisive factor for this method's success is the chosen variable ordering. Generally speaking, it is plausible that dependent variables should be brought close together in order to reduce BDD sizes. In planning, variable dependencies are typically captured by means of causal graphs, and in preceding work these were taken as the basis for finding BDD variable orderings. Starting from the observation that the two concepts of "dependency" are actually quite different, we introduce a framework for assessing the strength of variable ordering heuristics in sub-classes of planning. It turns out that, even for extremely simple planning tasks, causal graph based variable orders may be exponentially worse than optimal. Experimental results on a wide range of variable ordering variants corroborate our theoretical findings. Furthermore, we show that dynamic reordering is much more effective at reducing BDD size, but it is not cost-effective due to a prohibitive runtime overhead. We exhibit the potential of middle-ground techniques, running dynamic reordering until simple stopping criteria hold.
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Parlyuk, Ekaterina y Nikolay Bol'shakov. "METHODOLOGY FOR DETERMINING THE MAIN INDICATORS OF THE TEMPERATURE AND DYNAMIC CHARACTERISTICS OF THE COOLING SYSTEM OF AN ENERGY VEHICLE DURING OPERATION". Vestnik of Kazan State Agrarian University 16, n.º 2 (5 de agosto de 2021): 75–79. http://dx.doi.org/10.12737/2073-0462-2021-75-79.
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The efficiency of internal combustion engines of energy facilities operating in the conditions of enterprises of the agro-industrial complex depends on the stability of the thermal regime of the engine. Its provision is entrusted to the cooling system, in this article which is a radiator with a polyurethane core. The temperature regime of the engine operation affecting a number of factors is given and described - these are design parameters (design features of the radiator and the features of the working process of the radiator, taking into account the operating conditions of the tractor) and operational, which take into account the operating mode of the tractor and natural and climatic conditions. According to the research results during the operation of the tractor in steady conditions, the temperature of the coolant in the system is stable, respectively, the temperature field of the air flow at the inlet and outlet of the radiator with a polyurethane core also stabilizes. To take them into account, the coefficient of thermal properties of the radiator is introduced, which depends on the external and internal temperature-dynamic effects of the environment, and a diagram is constructed that shows the dependence of the temperature of the coolant flowing in the radiator on the generated load of the tractor during operation in the field. At the same time, the temperature-dynamic characteristic of the tractor does not depend on the design features of the engine, but on the power developed by the engine. Therefore, the heat removed from the engine into the coolant is calculated by us through the engine power. Based on this, the characteristic of the thermal balance of the engine and the heat transfer of the radiator during the operation of the tractor at full load are considered, taking into account the change in gears within the speed limits, a graph of the thermal balance of the engine and radiator versus speed is built. Based on the calculations, it was concluded that the use of the characteristics of the traction-dynamic balance of the tractor can serve as the basis for the general analysis and calculated and experimental operating modes of the automotive polymer radiator and the cooling system as a whole, taking into account the loads, climatic conditions and operating parameters of the cooling system
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Greulich, Philip, Ben D. MacArthur, Cristina Parigini y Rubén J. Sánchez-García. "Stability and steady state of complex cooperative systems: a diakoptic approach". Royal Society Open Science 6, n.º 12 (diciembre de 2019): 191090. http://dx.doi.org/10.1098/rsos.191090.
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Cooperative dynamics are common in ecology and population dynamics. However, their commonly high degree of complexity with a large number of coupled degrees of freedom renders them difficult to analyse. Here, we present a graph-theoretical criterion, via a diakoptic approach (divide-and-conquer) to determine a cooperative system’s stability by decomposing the system’s dependence graph into its strongly connected components (SCCs). In particular, we show that a linear cooperative system is Lyapunov stable if the SCCs of the associated dependence graph all have non-positive dominant eigenvalues, and if no SCCs which have dominant eigenvalue zero are connected by a path.
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KOSKINEN, JOHAN, ALBERTO CAIMO y ALESSANDRO LOMI. "Simultaneous modeling of initial conditions and time heterogeneity in dynamic networks: An application to Foreign Direct Investments". Network Science 3, n.º 1 (12 de febrero de 2015): 58–77. http://dx.doi.org/10.1017/nws.2015.3.
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AbstractIn dynamic networks, the presence of ties are subject both to endogenous network dependencies and spatial dependencies. Current statistical models for change over time are typically defined relative to some initial condition, thus skirting the issue of where the first network came from. Additionally, while these longitudinal network models may explain the dynamics of change in the network over time, they do not explain the change in those dynamics. We propose an extension to the longitudinal exponential random graph model that allows for simultaneous inference of the changes over time and the initial conditions, as well as relaxing assumptions of time-homogeneity. Estimation draws on recent Bayesian approaches for cross-sectional exponential random graph models and Bayesian hierarchical models. This is developed in the context of foreign direct investment relations in the global electricity industry in 1995–2003. International investment relations are known to be affected by factors related to: (i) the initial conditions determined by the geographical locations; (ii) time-dependent fluctuations in the global intensity of investment flows; and (iii) endogenous network dependencies. We rely on the well-known gravity model used in research on international trade to represent how spatial embedding and endogenous network dependencies jointly shape the dynamics of investment relations.
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LEE, YONG-HUN, MEIXUN JIN y JONG-HYEOK LEE. "Graph-Based Dependency Parsing Using Dynamic Features in Korean". International Journal of Computer Processing of Languages 23, n.º 02 (junio de 2011): 185–99. http://dx.doi.org/10.1142/s1793840611002280.
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Malburg, Jan, Alexander Finder y Görschwin Fey. "Debugging hardware designs using dynamic dependency graphs". Microprocessors and Microsystems 47 (noviembre de 2016): 347–59. http://dx.doi.org/10.1016/j.micpro.2016.10.004.
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Chard, Kyle, Yadu Babuji, Anna Woodard, Ben Clifford, Zhuozhao Li, Mihael Hategan, Ian Foster, Mike Wilde y Daniel S. Katz. "Extended Abstract". ACM SIGAda Ada Letters 40, n.º 2 (27 de abril de 2021): 73–75. http://dx.doi.org/10.1145/3463478.3463486.
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Parsl is a parallel programming library for Python that aims to make it easy to specify parallelism in programs and to realize that parallelism on arbitrary parallel and distributed computing systems. Parsl relies on developers annotating Python functions-wrapping either Python or external applications-to indicate that these functions may be executed concurrently. Developers can then link together functions via the exchange of data. Parsl establishes a dynamic dependency graph and sends tasks for execution on connected resources when dependencies are resolved. Parsl's runtime system enables different compute resources to be used, from laptops to supercomputers, without modification to the Parsl program.
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Li, Zuchao, Hai Zhao y Kevin Parnow. "Global Greedy Dependency Parsing". Proceedings of the AAAI Conference on Artificial Intelligence 34, n.º 05 (3 de abril de 2020): 8319–26. http://dx.doi.org/10.1609/aaai.v34i05.6348.
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Most syntactic dependency parsing models may fall into one of two categories: transition- and graph-based models. The former models enjoy high inference efficiency with linear time complexity, but they rely on the stacking or re-ranking of partially-built parse trees to build a complete parse tree and are stuck with slower training for the necessity of dynamic oracle training. The latter, graph-based models, may boast better performance but are unfortunately marred by polynomial time inference. In this paper, we propose a novel parsing order objective, resulting in a novel dependency parsing model capable of both global (in sentence scope) feature extraction as in graph models and linear time inference as in transitional models. The proposed global greedy parser only uses two arc-building actions, left and right arcs, for projective parsing. When equipped with two extra non-projective arc-building actions, the proposed parser may also smoothly support non-projective parsing. Using multiple benchmark treebanks, including the Penn Treebank (PTB), the CoNLL-X treebanks, and the Universal Dependency Treebanks, we evaluate our parser and demonstrate that the proposed novel parser achieves good performance with faster training and decoding.
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Yordanov, Pencho y Jörg Stelling. "Efficient manipulation and generation of Kirchhoff polynomials for the analysis of non-equilibrium biochemical reaction networks". Journal of The Royal Society Interface 17, n.º 165 (abril de 2020): 20190828. http://dx.doi.org/10.1098/rsif.2019.0828.
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Kirchhoff polynomials are central for deriving symbolic steady-state expressions of models whose dynamics are governed by linear diffusion on graphs. In biology, such models have been unified under a common linear framework subsuming studies across areas such as enzyme kinetics, G-protein coupled receptors, ion channels and gene regulation. Due to ‘history dependence’ away from thermodynamic equilibrium, these models suffer from a (super) exponential growth in the size of their symbolic steady-state expressions and, respectively, Kirchhoff polynomials. This algebraic explosion has limited applications of the linear framework. However, recent results on the graph-based prime factorization of Kirchhoff polynomials may help subdue the combinatorial complexity. By prime decomposing the graphs contained in an expression of Kirchhoff polynomials and identifying the graphs giving rise to equal polynomials, we formulate a coarse-grained variant of the expression suitable for symbolic simplification. We devise criteria to efficiently test the equality of Kirchhoff polynomials and propose two heuristic algorithms to explicitly generate individual Kirchhoff polynomials in a compressed form; they are inspired by algebraic simplifications but operate on the corresponding graphs. We illustrate the practicality of the developed theory and algorithms for a diverse set of graphs of different sizes and for non-equilibrium gene regulation analyses.
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Shahpasand, Maryam, Mehdi Shajari, Seyed Alireza Hashemi Golpaygani y Hoda Ghavamipoor. "A comprehensive security control selection model for inter-dependent organizational assets structure". Information & Computer Security 23, n.º 2 (8 de junio de 2015): 218–42. http://dx.doi.org/10.1108/ics-12-2013-0090.
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Purpose – This paper aims to propose a comprehensive model to find out the most preventive subset of security controls against potential security attacks inside the limited budget. Deploying the appropriate collection of information security controls, especially in information system-dependent organizations, ensures their businesses' continuity alongside with their effectiveness and efficiency. Design/methodology/approach – Impacts of security attacks are measured based on interdependent asset structure. Regarding this objective, the asset operational dependency graph is mapped to the security attack graph to assess the risks of attacks. This mapping enables us to measure the effectiveness of security controls against attacks. The most effective subset is found by mapping its features (cost and effectiveness) to items’ features in a binary knapsack problem, and then solving the problem by a modified version of the classic dynamic programming algorithm. Findings – Exact solutions are achieved using the dynamic programming algorithm approach in the proposed model. Optimal security control subset is selected based on its implementation cost, its effectiveness and the limited budget. Research limitations/implications – Estimation of control effectiveness is the most significant limitation of the proposed model utilization. This is caused by lack of experience in risk management in organizations, which forces them to rely on reports and simulation results. Originality/value – So far, cost-benefit approaches in security investments are followed only based on vulnerability assessment results. Moreover, dependency weights and types in interdependent structure of assets have been taken into account by a limited number of models. In the proposed model, a three-dimensional graph is used to capture the dependencies in risk assessment and optimal control subset selection, through a holistic approach.
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Veliz-Cuba, Alan y Reinhard Laubenbacher. "Dynamics of semilattice networks with strongly connected dependency graph". Automatica 99 (enero de 2019): 167–74. http://dx.doi.org/10.1016/j.automatica.2018.10.031.
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Diao, Zulong, Xin Wang, Dafang Zhang, Yingru Liu, Kun Xie y Shaoyao He. "Dynamic Spatial-Temporal Graph Convolutional Neural Networks for Traffic Forecasting". Proceedings of the AAAI Conference on Artificial Intelligence 33 (17 de julio de 2019): 890–97. http://dx.doi.org/10.1609/aaai.v33i01.3301890.
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Graph convolutional neural networks (GCNN) have become an increasingly active field of research. It models the spatial dependencies of nodes in a graph with a pre-defined Laplacian matrix based on node distances. However, in many application scenarios, spatial dependencies change over time, and the use of fixed Laplacian matrix cannot capture the change. To track the spatial dependencies among traffic data, we propose a dynamic spatio-temporal GCNN for accurate traffic forecasting. The core of our deep learning framework is the finding of the change of Laplacian matrix with a dynamic Laplacian matrix estimator. To enable timely learning with a low complexity, we creatively incorporate tensor decomposition into the deep learning framework, where real-time traffic data are decomposed into a global component that is stable and depends on long-term temporal-spatial traffic relationship and a local component that captures the traffic fluctuations. We propose a novel design to estimate the dynamic Laplacian matrix of the graph with above two components based on our theoretical derivation, and introduce our design basis. The forecasting performance is evaluated with two realtime traffic datasets. Experiment results demonstrate that our network can achieve up to 25% accuracy improvement.
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Krich, Christopher, Jakob Runge, Diego G. Miralles, Mirco Migliavacca, Oscar Perez-Priego, Tarek El-Madany, Arnaud Carrara y Miguel D. Mahecha. "Estimating causal networks in biosphere–atmosphere interaction with the PCMCI approach". Biogeosciences 17, n.º 4 (26 de febrero de 2020): 1033–61. http://dx.doi.org/10.5194/bg-17-1033-2020.
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Abstract. The dynamics of biochemical processes in terrestrial ecosystems are tightly coupled to local meteorological conditions. Understanding these interactions is an essential prerequisite for predicting, e.g. the response of the terrestrial carbon cycle to climate change. However, many empirical studies in this field rely on correlative approaches and only very few studies apply causal discovery methods. Here we explore the potential for a recently proposed causal graph discovery algorithm to reconstruct the causal dependency structure underlying biosphere–atmosphere interactions. Using artificial time series with known dependencies that mimic real-world biosphere–atmosphere interactions we address the influence of non-stationarities, i.e. periodicity and heteroscedasticity, on the estimation of causal networks. We then investigate the interpretability of the method in two case studies. Firstly, we analyse three replicated eddy covariance datasets from a Mediterranean ecosystem. Secondly, we explore global Normalised Difference Vegetation Index time series (GIMMS 3g), along with gridded climate data to study large-scale climatic drivers of vegetation greenness. We compare the retrieved causal graphs to simple cross-correlation-based approaches to test whether causal graphs are considerably more informative. Overall, the results confirm the capacity of the causal discovery method to extract time-lagged linear dependencies under realistic settings. For example, we find a complete decoupling of the net ecosystem exchange from meteorological variability during summer in the Mediterranean ecosystem. However, cautious interpretations are needed, as the violation of the method's assumptions due to non-stationarities increases the likelihood to detect false links. Overall, estimating directed biosphere–atmosphere networks helps unravel complex multidirectional process interactions. Other than classical correlative approaches, our findings are constrained to a few meaningful sets of relations, which can be powerful insights for the evaluation of terrestrial ecosystem models.
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Engels, Gregor, Reiko Heckel, Gabriele Taentzer y Hartmut Ehrig. "A Combined Reference Model- and View-Based Approach to System Specification". International Journal of Software Engineering and Knowledge Engineering 07, n.º 04 (diciembre de 1997): 457–77. http://dx.doi.org/10.1142/s0218194097000266.
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The idea of a combined reference model- and view-based specification approach has been proposed recently in the software engineering community. In this paper we present a specification technique based on graph transformations which supports such a development approach. The use of graphs and graph transformations supports an intuitive understanding and an integration of static and dynamic aspects on a well-defined semantical base. On this background, formal notions of view and view relation are developed and the behaviour of views is described by a loose semantics. The integration of two views derived from a common reference model is done in two steps. First, dependencies between the views which are not given by the reference model are determined, and the reference model is extended appropriately. This is the task of a model manager. If the two views and the reference model are consistent, the actual view integration can be performed automatically. For the case of more than two views more general scenarios are developed and discussed. All concepts and results are illustrated at the well-known example of a banking system.
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Elmaghraoui, Hajar, Laila Benhlima y Dalila Chiadmi. "Automatic Dynamic Web Service Composition Using AND/OR Directed Graphs". International Journal of Web Services Research 16, n.º 3 (julio de 2019): 29–43. http://dx.doi.org/10.4018/ijwsr.2019070102.
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In this article, the authors propose a dynamic web service composition approach based on representing the semantic relationship between web services using a weighted directed AND/OR graph. The nodes in this graph represent available services while the arcs represent the semantic input/output dependencies among them. The novelty of this work consists of constructing the graph and computing offline the shortest paths between each pair of its nodes to disconnect this tedious task from the composition query process. A set of dynamic optimization techniques has been included to reduce the size of the graph and thus improve the scalability and performance of this approach. In addition to the sequence and fork relations between services, this solution also supports the parallel relation. Furthermore, a recovery mechanism is integrated to ensure the continuity of the execution of the composition.
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HADZHIEV, BORISLAV, KATJA WINDT, WERNER BERGHOLZ y MARC-THORSTEN HÜTT. "A MODEL OF GRAPH COLORING DYNAMICS WITH ATTENTION WAVES AND STRATEGIC WAITING". Advances in Complex Systems 12, n.º 06 (diciembre de 2009): 549–64. http://dx.doi.org/10.1142/s0219525909002386.
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Recently, Kearns et al. [Kearns, M., Suri, S. and Montfort, N., An experimental study of the coloring problem on human subject networks, Science313 (2006) 824–827] studied the topology dependence of graph coloring dynamics. In their empirical study, the authors analyze, how a network of human subjects acting as autonomous agents performs in solving a conflict-avoidance task (the graph coloring problem) for different network architectures. A surprising result was that the run-time of the empirical dynamics decreases with the number of shortcuts in a Watts–Strogatz small-world graph. In a simulation of the dynamics based on randomly selecting color conflicts for update, they observe a strong increase of the run-time with the number of shortcuts. Here, we propose classes of strategies, which are capable of explaining the decrease in run-time with an increasing number of shortcuts. We show that the agent's strategy, the graph topology, and the complexity of the problem (essentially given by the graph's chromatic number) interact nontrivially yielding unexpected insights into the problem-solving capacity of organizational structures.
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HOLME, PETTER. "CONGESTION AND CENTRALITY IN TRAFFIC FLOW ON COMPLEX NETWORKS". Advances in Complex Systems 06, n.º 02 (junio de 2003): 163–76. http://dx.doi.org/10.1142/s0219525903000803.
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The central points of communication network flow have often been identified using graph theoretical centrality measures. In real networks, the state of traffic density arises from an interplay between the dynamics of the flow and the underlying network structure. In this work we investigate the relationship between centrality measures and the density of traffic for some simple particle hopping models on networks with emerging scale-free degree distributions. We also study how the speed of the dynamics are affected by the underlying network structure. Among other conclusions, we find that, even at low traffic densities, the dynamical measure of traffic density (the occupation ratio) has a non-trivial dependence on the static centrality (quantified by "betweenness centrality"), where non-central vertices get a comparatively large portion of the traffic.
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Петровский, Валерий, Valeriy Petrovskiy, Анатолий Рубан y Anatoliy Ruban. "Studying wear resistance of steel friction pairs under high contact pressure in water-abrasive medium". Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2019, n.º 4 (15 de noviembre de 2019): 23–29. http://dx.doi.org/10.24143/2073-1574-2019-4-23-29.
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The paper is focused on the problem of the service life of the dredger chain, which largely depends on the efficiency and reliability of the hinge joint, when a mineral abrasive gets into the structural gap resulting in rapid wear of the joint under high dynamic loads. There has been developed a science-based technology of repairing parts of the assembly, without reducing the resource, from cheap and accessible (non-deficient) materials, taking into account modern technical and economic requirements, on samples. Wear resistance of samples of friction pairs has been defined in terms of a chain operating model. The research method is based on comparing the wear rate of samples in a pair made of steel 110Mn13 (sleeve - pin), 110Mn13 and 38CrNi3M (sleeve - pin), according to the standard technologies and taken as a reference, with pairs made of steel 110Mn13, C45K, facing with wire SV08A, electrodes E50A – UONI 13/55 and E – 190Cr5Si7 – LEZ – T – 590 – NG after heat treatment, chemical and heat treatment, surface plastic deformation. Samples were tested in the water-abrasive environment with a load of 6615 N (675 kgf). The wear resistance parameters were determined as following: 1) reference pairs of steel 110Mn13 (bushing-pin) and 110Mn13 (bushing), 38CrNi3Mo (pin); 2) pairs of steel 110Mn13 (bushing) and facing with wire SV08A (pin); 3) pairs of steel 110Mn13 (bushing) and cladding with electrodes
E–190Cr5Si7–LEZ –T–590– NG (pin); 4) pairs of steel C45K (bushing) and cladding with
E –190Cr5Si7 – LEZ – T – 590 – NG electrodes (pin); 5) pairs of steel C45K (bushing) and clad-ding with E50A – UONI 13/55 electrodes (pin). A graph of dependence of the bushing and pin wear on the relations of initial hardness and structures of friction pair has been built. It is recom-mended to restore the pin with wear-resistant electrodes E – 190Cr5Si7 – LEZ – T – 590 – NG paired with 110Mn13 steel bushing with surface plastic deformation. The wear resistance of a pair, with a different combination of structures, does not depend on the ratio of hardness of Hsl / Hfin. The materials of the pair worn within the reference samples can be recommended for the operational tests.