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Detrimental role of fluctuations in the resource dependency networks

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arXiv 2022年

作者： Kulkarni, Saumitra Shekatkar, Snehal M. Department of Scientific Computing Modeling and Simulation Savitribai Phule Pune University Pune411007 India

Individual components of many real-world complex networks produce and exchange resources among themselves. However, because the resource production in such networks is almost always stochastic, fluctuations in the production are unavoidable. In this paper, we study the effect of fluctuations on the resource dependencies in complex networks. To this end, we consider a modification of a threshold model of resource dependencies in networks that was recently proposed, where each vertex has a fitness that depends on the total amount of resource it has produced, the amount it has procured from its neighbours, and the fitness threshold. We study how the "network fitness", defined as the average fitness of vertices in the network, is affected as the fluctuation size is varied. We show that the fluctuations worsen the network fitness even when average production on vertices is kept fixed. This is true independent of whether more than required amount is produced in the network or not. However, this effect saturates for large fluctuations, and hence very large fluctuations cannot worsen the network fitness beyond a limit. We further show that the networks with a homogeneous degree distribution, such as the Erdős-Rényi network, are less affected by fluctuations and also produce lower wastage than the networks with a heterogeneous degree distribution like the Scale-Free network. Our work shows that fluctuations in the resource production should be avoided in resource dependency networks. Copyright © 2022, The Authors. All rights reserved.

关键词： Complex networks

Resource dependency and survivability in complex networks

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arXiv 2020年

作者： Ingale, Madhusudan Shekatkar, Snehal M. Department Of Scientific Computing Modeling And Simulation Savitribai Phule Pune University Pune411007 India

Components in many real-world complex systems depend on each other for the resources required for survival, and may die of a shortage. These patterns of dependencies often take the form of a complex network whose structure potentially affects how the resources produced in the system are efficiently shared among its components, which in turn decides a network's survivability. Here we present a simple threshold model that provides insight into this relationship between the network structure and survivability. We show that, as a combined effect of local sharing and finite lifetime of resources, many components in a complex system may die of lack of resources even when sufficient amount is available in the system. We also obtain a surprising result that although the scale-free networks exhibit a significantly higher survivability compared to their homogeneous counterparts, a vertex in the later survives longer on average. Finally, we demonstrate that the system's survivability can be substantially improved by changing the way vertices distribute resources among the neighbours. Our work is a step towards understanding the relationship between intricate resource dependencies present in many real-world complex systems and their survivability. Copyright © 2020, The Authors. All rights reserved.

关键词： Complex networks

On the relative abundances of Cavansite and Pentagonite

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arXiv 2023年

作者： Pujari, Bhalchandra S. Gehlot, Sagar Arjunwadkar, Mihir Kanhere, Dilip G. Duraiswami, Raymond A. Department of Scientific Computing Modeling & Simulation Savitribai Phule Pune University Pune411007 India Department of Geology Savitribai Phule Pune University Pune411007 India

Cavansite is a visually stunning blue vanadosilicate mineral with limited occurrences worldwide, whereas Pentagonite is a closely related dimorph with similar physical and chemical properties, yet is extremely rare compared to Cavansite. The reasons behind Pentagonite’s exceptional rarity remain largely unknown. In this study, (a) density functional theory (DFT) is utilized to investigate the electronic structures of Cavansite and Pentagonite at ground state and finite pressures;(b) a two-state Boltzmann probability model is then employed to construct a comprehensive phase diagram that reveals the abundance of each species across a wide range of pressure and temperature conditions;and (c) dehydration characteristics of these two minerals are explored. The present analysis reveals the key factors that contribute to the relative scarcity of Pentagonite, including differences in structural arrangement and electronic configurations between the two minerals. Specifically, it shows that (a) because of the peculiar arrangements of SiO4 polyhedra, Cavansite forms a compact structure (about 2.7% less in volume) resulting in lower energy;(b) at a temperature of about 650K only about 1% Pentagonite can form;(c) vanadium induces a highly localized state in both of these otherwise large-band-gap insulators resulting in an extremely weak magnetic phase that is unlikely to be observed at any reasonable finite temperature;and (d) water molecules are loosely bound inside the microporous crystals of Cavansite and Pentagonite, suggesting potential applications of these minerals in various technological fields. © 2023, CC BY-NC-ND.

关键词： Electronic structure

Insights into Effect of Dopant Site and Dopant Concentration on Structural, Electronic and Optical Properties of Ganbo4 and its Implications on Visible Light Photocatalytic Behavior: An Ab-Initio Study

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SSRN

SSRN 2024年

作者： Shah, Vaishali Mascarenhas, David Deshmukh, Ankosh D. Kshirsagar, Bhakti Department of Scientific Computing Modeling and Simulation Savitribai Phule Pune University Pune411007 India Department of Physics Savitribai Phule Pune University Pune411007 India

First principles electronic structure calculations were performed on pure and chalcogenide doped GaNbO4. Doping with isoelectronic S and Se at the O sites in GaNbO4 shows a dopant site driven anisotropy in the structural properties which affects its electronic, optical and photocatalytic behavior. Band gap reduction in GaNbO4 is more with Se than S and this reduction can be regulated via choice of dopant, dopant site and dopant concentration. GaNbO4 bears an optical absorption profile similarity with anatase TiO2 (a-TiO2). Besides directional anisotropy, dopant induced absorption in the visible regime displays a site driven anisotropy, which, has implications on the onset of absorption and absorption peak heights. The visible region absorption peaks can be modulated with changes in the dopant concentration. Se dopant at a lower concentration gives a broader visible regime absorption peak of similar peak height as of a higher concentration S dopant. Undoped GaNbO4 has valence band maxima and conduction band minima at similar energies as a-TiO2 and these band placements can be altered through choice of dopant element, dopant site and dopant concentration to tune the visible light photocatalytic performance. Our study shows that doped GaNbO4 has a stronger visible range absorption than doped a-TiO2. © 2024, The Authors. All rights reserved.

关键词： Titanium dioxide

A second order constitutive theory for polyatomic gases: theory and applications

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arXiv 2023年

作者： Rana, Anirudh Singh Barve, Sukratu Department of Mathematics BITS Pilani Pilani Campus Rajasthan333031 India Department of Scientific Computing Modeling and Simulation Savitribai Phule Pune University Pune411007 India

In the classical irreversible thermodynamics (CIT) framework, the Navier-Stokes-Fourier (NSF) constitutive equations are obtained so as they satisfy the entropy inequality, by and large assuming that the entropy flux is equal to the heat flux over the temperature. This article is focused on the derivation of second-order constitutive equations for polyatomic gases;it takes the basis of CIT, but most importantly, allowing up to quadratic nonlinearities in the entropy flux. Mathematical similarities between the proposed model and the classic Stokes-Laplace equations are exploited so as to construct analytic/semi-analytic solutions for the slow rarefied gas flow over different shapes. A set of second-order boundary conditions are formulated such that the model’s prediction for the drag force is in excellent agreement with the experimental data over the whole range of Knudsen number. We have also computed the normal shock structure in nitrogen for Mach Ma . 4. A very good agreement was observed with the kinetic theory, as well as with the experimental data. © 2023, CC BY.

关键词： Constitutive equations

Csfex3 (X = F, Cl, Br, I) a Novel Spintronic Material with IR Absorption and High Refractive Index: First Principles Investigations

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SSRN

SSRN 2024年

作者： Shah, Vaishali Kshirsagar, Bhakti Department of Scientific Computing Modeling and Simulation Savitribai Phule Pune University Pune411007 India Department of Physics Savitribai Phule Pune University Pune411007 India

We have studied the structural, electronic, optical, mechanical and thermodynamic properties of cesium ferrous trihalides CsFeX3 (X = F, Cl, Br, I) using ab-initio total energy calculations. Our investigations show that CsFeX3 compounds are 100% spin-polarized, with the spin-up electrons exhibiting semiconducting behavior and the spin-down electrons showing metallic behavior. We have performed DFT+U calculations to confirm their half-metallic nature is preserved with different values of the Coulomb interaction potential. The study of optical properties shows that all these materials have high refractive index and optical absorption in the IR region with CsFeF3 , having the highest and CsFeI3 the lowest absorption peak in this regime. Only CsFeCl3 and CsFeBr3 satisfy the Born criteria of mechanical stability. CsFeBr3 was found to be more ductile and CsFeCl3 to have smaller anisotropy in the Poisson's ratio, shear and Young's modulus. CsFeCl3 is the most promising cesium ferrous trihalide for spintronic and IR-region optoelectronic device applications due to its half-metallic and good optical, mechanical and thermodynamic properties. © 2024, The Authors. All rights reserved.

关键词： Thermodynamic properties

ON PARTIAL INFORMATION RETRIEVAL: THE UNCONSTRAINED 100 PRISONER PROBLEM

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arXiv 2020年

作者： Lodato, Ivano Shekatkar, Snehal M. Wong, Tian An Allos Limited Hong Kong Department of Scientific Computing Modeling and Simulation Savitribai Phule Pune University Pune411007 India Department of Mathematics and Statistics University of Michigan DearbornMI48126 United States

We consider a generalization of the classical 100 Prisoner problem and its variant, involving empty boxes, whereby winning probabilities for a team depend on the number of attempts, as well as on the number of winners. We call this the unconstrained 100 prisoner problem. After introducing the 3 main classes of strategies, we define a variety of 'hybrid' strategies and quantify their winning-efficiency. Whenever analytic results are not available, we make use of Monte Carlo simulations to estimate with high accuracy the winning-probabilities. Based on the results obtained, we conjecture that all strategies, except for the strategy maximizing the winning probability of the classical (constrained) problem, converge to the random strategy under weak conditions on the number of players or empty boxes. We conclude by commenting on the possible applications of our results in understanding processes of information retrieval, such as "memory" in living organisms. Copyright © 2020, The Authors. All rights reserved.

关键词： Information retrieval

Effect of money heterogeneity on resource dependency in complex networks

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arXiv 2022年

作者： Agrawal, Harshit Lahorkar, Ashwin Shekatkar, Snehal M. Studio Sirah Bengaluru560037 India Pitney Bowes India Pvt. Ltd Pune411014 India Department of Scientific Computing Modeling and Simulation S.P. Pune University Pune411007 India

Exchange of resources among individual components of a system is fundamental to systems like a social network of humans and a network of cities and villages. For various reasons, the human society has come up with the notion of money as a proxy for the resources. Here we extend the model of resource dependencies in networks that was recently proposed by one of us, by incorporating the concept of money so that the vertices of a network can sell and buy required resources among themselves. We simulate the model using the configuration model as a substrate for homogeneous as well as heterogeneous degree distributions and using various exchange strategies. We show that a moderate amount of initial heterogeneity in the money on the vertices can significantly improve the survivability of Scale-free networks but not that of homogeneous networks like the Erdős-Rényi network. Our work is a step towards understanding the effect of presence of money on the resource distribution dynamics in complex networks. Copyright © 2022, The Authors. All rights reserved.

关键词： Complex networks

SCIRun/BioPSE: integrated problem solving environment for bioelectric field problems and visualization

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SCIRun/BioPSE: integrated problem solving environment for bi...

IEEE International Symposium on Biomedical Imaging

作者： R.S. MacLeod O.M. Weinstein J. Davison de St Germain D.H. Brooks C.R. Johnson S.G. Parker Scientific Computing and Imaging Institute University of Utah Salt Lake UT USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Center for Bioelectric Field Modeling Simulation and Visualization NIH/NCRR

SCIRun is a general purpose problem solving environment that seeks to integrate the steps of preparing, executing, and visualizing simulations of physical and biological systems. The implementation of SCIRun is by means of an interactive dataflow network consisting of modules and data pipes exposed as a visual programming language. SCIRun also contains specific modules for bioelectric field simulations and visualizations and the combination of SCIRun with this package is known as BioPSE (***/software/biopse). This software has been in the public domain since 2000 and in that time we have developed strategies for software development, engineering, testing, documentation, and training. We have also continued to expand the scope of the SCIRun/BioPSE package not only through our own codes but by constructing bridges to other systems, both open source and proprietary. We have also created a repository for relevant sample networks and datasets with the aim of allowing diverse groups to test and evaluate algorithms using identical data and to share their results with the community for comparison of performance and accuracy. We present here a summary of the software system and describe specific experiences and conclusions with regard to creating and managing a large open source software project carried out within a university setting.

关键词： Biopsy Problem-solving Bioelectric phenomena Data visualization Biological system modeling Packaging Biological systems Computer languages Software packages Programming