scholarly journals Generation of Spatially Embedded Random Networks to Model Complex Transportation Networks

Author(s):  
J. Hackl ◽  
B. T. Adey
Author(s):  
Jeffrey L. Adler

For a wide range of transportation network path search problems, the A* heuristic significantly reduces both search effort and running time when compared to basic label-setting algorithms. The motivation for this research was to determine if additional savings could be attained by further experimenting with refinements to the A* approach. We propose a best neighbor heuristic improvement to the A* algorithm that yields additional benefits by significantly reducing the search effort on sparse networks. The level of reduction in running time improves as the average outdegree of the network decreases and the number of paths sought increases.


2003 ◽  
Vol 68 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Stanislav Záliš ◽  
Antonín Vlček ◽  
Chantal Daniel

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.


Author(s):  
Eun-Young Mun ◽  
Anne E. Ray

Integrative data analysis (IDA) is a promising new approach in psychological research and has been well received in the field of alcohol research. This chapter provides a larger unifying research synthesis framework for IDA. Major advantages of IDA of individual participant-level data include better and more flexible ways to examine subgroups, model complex relationships, deal with methodological and clinical heterogeneity, and examine infrequently occurring behaviors. However, between-study heterogeneity in measures, designs, and samples and systematic study-level missing data are significant barriers to IDA and, more broadly, to large-scale research synthesis. Based on the authors’ experience working on the Project INTEGRATE data set, which combined individual participant-level data from 24 independent college brief alcohol intervention studies, it is also recognized that IDA investigations require a wide range of expertise and considerable resources and that some minimum standards for reporting IDA studies may be needed to improve transparency and quality of evidence.


2021 ◽  
Vol 11 (9) ◽  
pp. 3867
Author(s):  
Zhewei Liu ◽  
Zijia Zhang ◽  
Yaoming Cai ◽  
Yilin Miao ◽  
Zhikun Chen

Extreme Learning Machine (ELM) is characterized by simplicity, generalization ability, and computational efficiency. However, previous ELMs fail to consider the inherent high-order relationship among data points, resulting in being powerless on structured data and poor robustness on noise data. This paper presents a novel semi-supervised ELM, termed Hypergraph Convolutional ELM (HGCELM), based on using hypergraph convolution to extend ELM into the non-Euclidean domain. The method inherits all the advantages from ELM, and consists of a random hypergraph convolutional layer followed by a hypergraph convolutional regression layer, enabling it to model complex intraclass variations. We show that the traditional ELM is a special case of the HGCELM model in the regular Euclidean domain. Extensive experimental results show that HGCELM remarkably outperforms eight competitive methods on 26 classification benchmarks.


2021 ◽  
Vol 13 (2) ◽  
pp. 22
Author(s):  
Xavier Boulet ◽  
Mahdi Zargayouna ◽  
Gérard Scemama ◽  
Fabien Leurent

Modeling and simulation play an important role in transportation networks analysis. In the literature, authors have proposed many traffic and mobility simulations, with different features and corresponding to different contexts and objectives. They notably consider different scales of simulations. The scales refer to the represented entities, as well as to the space and the time representation of the transportation environment. However, we often need to represent different scales in the same simulation, for instance to represent a neighborhood interacting with a wider region. In this paper, we advocate for the reuse of existing simulations to build a new multi-scale simulation. To do so, we propose a middleware model to couple independent mobility simulations, working at different scales. We consider all the necessary processing and workflow to allow for a coherent orchestration of these simulations. We also propose a prototype implementation of the middleware. The results show that such a middleware is capable of creating a new multi-scale mobility simulation from existing ones, while minimizing the incoherence between them. They also suggest that, to have a maximal benefit from the middleware, existing mobility simulation platforms should allow for an external control of the simulations, allowing for executing a time step several times if necessary.


Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 976
Author(s):  
R. Aguilar-Sánchez ◽  
J. Méndez-Bermúdez ◽  
José Rodríguez ◽  
José Sigarreta

We perform a detailed computational study of the recently introduced Sombor indices on random networks. Specifically, we apply Sombor indices on three models of random networks: Erdös-Rényi networks, random geometric graphs, and bipartite random networks. Within a statistical random matrix theory approach, we show that the average values of Sombor indices, normalized to the order of the network, scale with the average degree. Moreover, we discuss the application of average Sombor indices as complexity measures of random networks and, as a consequence, we show that selected normalized Sombor indices are highly correlated with the Shannon entropy of the eigenvectors of the adjacency matrix.


Author(s):  
Ramyar Saeedi ◽  
Malarvizhi Sankaranarayanasamy ◽  
Rahul Vishwakarma ◽  
Prasun Singh ◽  
Ravigopal Vennelakanti

Sign in / Sign up

Export Citation Format

Share Document