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891.
《Discrete Mathematics》2023,346(2):113222
Hypergraphic matroids were studied first by Lorea [23] and later by Frank et al. [11]. They can be seen as generalizations of graphic matroids. Here we show that several algorithms developed for the graphic case can be extended to hypergraphic matroids. We treat the following: the separation problem for the associated polytope, testing independence, separation of partition inequalities, computing the rank of a set, computing the strength, computing the arboricity and network reinforcement. 相似文献
892.
The current study aimed to explore the anti-type 2 diabetes mellitus (T2DM) mechanism of guava leaf based on network pharmacology. The compounds contained in guava leaf was summarized from the literature, and a series of databases was used to identify the active components and corresponding potential targets. The intersection between diabetes-associated genes searched in the GeneCard database and the predicted targets of guava leaf active components was defined as target genes, which were then used to construct a “compound-active components-target genes” pharmacological network. The biological functions and pathway enrichment analyses of target genes were performed in KOBAS 3.0. The differential expression analysis of GSE76894 was performed to obtain the differential expressed genes (DEGs) in T2DM patients by comparing non-diabetic controls. Finally, the intersection between DEGs and target genes were named key genes, and the representative pathways in which these genes were involved were drawn through KEGG Mapper. We found that the active components of guava leaf may regulate the PI3K-AKT signaling pathway, T2DM regulation process, and insulin resistance pathway, which was evidenced by KEGG pathway analysis of key genes. These results implied that guava leaf has a potential anti-T2DM property and its mode of action may be exerted via regulating insulin secretion and reducing blood sugar level. 相似文献
893.
Brenda Betancourt Abel Rodríguez Naomi Boyd 《Journal of computational and graphical statistics》2017,26(4):840-850
We propose a multinomial logistic regression model for link prediction in a time series of directed binary networks. To account for the dynamic nature of the data, we employ a dynamic model for the model parameters that is strongly connected with the fused lasso penalty. In addition to promoting sparseness, this prior allows us to explore the presence of change points in the structure of the network. We introduce fast computational algorithms for estimation and prediction using both optimization and Bayesian approaches. The performance of the model is illustrated using simulated data and data from a financial trading network in the NYMEX natural gas futures market. Supplementary material containing the trading network dataset and code to implement the algorithms is available online. 相似文献
894.
We investigate a two-dimensional network simulator that models the dynamics of two-phase immiscible bulk flow where film flow can be neglected. We present a method for simulating the detailed dynamical process where the two phases are allowed to break up into bubbles, and bubbles are allowed to merge together. The notions of drainage and imbibition are not adequate to describe this process since there is no clear front between the fluids. In fact, the simulator is constructed so that one can study the behaviour of the system far from inlets and outlets, where the two fluids have been mixed together so much that all initial fronts have broken up. The simulator gives the fractional flow as a function of the saturation of each of the fluids. For the case of two fluids with equal viscosity, we classify flow regimes that are parametrized by the capillary number. 相似文献
895.
896.
897.
Walid Mohamed Mahmud Ji Youn Arns Adrian Sheppard Mark A. Knackstedt W. Val Pinczewski 《Transport in Porous Media》2007,66(3):481-493
In a previous study Arns et al. (2004, Transport Porous Media
55, 21–46) we considered the role of topology on drainage relative permeability curves computed using network models derived
from a suite of tomographic images of Fontainebleau sandstone. The present study extends the analysis to more complex imbibition
displacements where the non-wetting fluid can be disconnected by snap-off as a result of swelling of wetting films in the
corners of pores and throats. In contrast to the findings for drainage displacements which showed that relative permeabilities
are significantly affected by network topology, the present study shows that the effect of topology on imbibition relative
permeabilities depends on the level of snap-off. For strongly wetting conditions where snap-off dominates the displacement
the effect of network topology is significantly smaller than for weakly wet conditions where snap-off is suppressed. For contact
angles sufficiently large to completely suppress snap-off, the effect of topology on imbibition relative permeabilities is
similar to that for drainage displacements. The findings are valid for random networks and for networks displaying short-range
pore–throat and longer range spatial correlations. 相似文献
898.
F. A. L. Dullien 《Transport in Porous Media》1991,6(5-6):581-606
Pore size and pore size distribution are defined, 1-D pore structure models, 2-D and 3-D network models of pore structure are reviewed. Simulation of capillary pressure and relative permeability curves with the help of network models of pore structure is discussed. Pore structure determination from serial sections is outlined. Phase immobilization technique is reviewed. 相似文献
899.
Eugen Cre
u 《Fuzzy Sets and Systems》2002,130(3):305
Binary operations with fuzzy sets using parallel computing are investigated. A parallel algorithm for merging pairs is presented with a special functionality of the comparators. 相似文献
900.
In this study H2O2/CoCl2 system was used as an oxidative environment to investigate the in vitro degradation behavior of a crosslinked polyesterurethane network. Weight loss, water absorption, mechanical properties, swelling degree and gel content were determined as a function of degradation time. The results showed that the H2O2/CoCl2 system could effectively accelerate the degradation of the polyurethanes. The samples had almost completely degraded after 84 days of incubation in a 3% H2O2/2% CoCl2 solution at 37 °C. The weight loss process could be approximately divided into three major phases: the weight decreased slowly during an induction phase (1), which was followed by a phase characterized by accelerated weight loss (2), and finally by a phase showing slow linear weight loss until complete erosion (3). The attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra of degraded polyurethane networks showed that the polyurethane underwent chain scission of the copolyester segment chains, and the joints of copolyester and 2,2,4- and 2,4,4-trimethylhexamethylene during degradation in the oxidative environment. The glass transition temperature of degraded polyesterurethane networks decreased significantly with increasing degradation time. From these results the H2O2/CoCl2 system can be used as an oxidative condition to evaluate the in vitro degradability of polyesterurethane. 相似文献