Overview of Deep Bed Filtration: Different Types and Mathematical Models

Author(s):  
Saravanamuthu Vigneswaran ◽  
Roger Ben Aim
2021 ◽  
pp. 1-21
Author(s):  
Muhammad Shabir ◽  
Rimsha Mushtaq ◽  
Munazza Naz

In this paper, we focus on two main objectives. Firstly, we define some binary and unary operations on N-soft sets and study their algebraic properties. In unary operations, three different types of complements are studied. We prove De Morgan’s laws concerning top complements and for bottom complements for N-soft sets where N is fixed and provide a counterexample to show that De Morgan’s laws do not hold if we take different N. Then, we study different collections of N-soft sets which become idempotent commutative monoids and consequently show, that, these monoids give rise to hemirings of N-soft sets. Some of these hemirings are turned out as lattices. Finally, we show that the collection of all N-soft sets with full parameter set E and collection of all N-soft sets with parameter subset A are Stone Algebras. The second objective is to integrate the well-known technique of TOPSIS and N-soft set-based mathematical models from the real world. We discuss a hybrid model of multi-criteria decision-making combining the TOPSIS and N-soft sets and present an algorithm with implementation on the selection of the best model of laptop.


2011 ◽  
Vol 11 (02) ◽  
pp. 215-236 ◽  
Author(s):  
MATTEO BROGGI ◽  
ADRIANO CALVI ◽  
GERHART I. SCHUËLLER

Cylindrical shells under axial compression are susceptible to buckling and hence require the development of enhanced underlying mathematical models in order to accurately predict the buckling load. Imperfections of the geometry of the cylinders may cause a drastic decrease of the buckling load and give rise to the need of advanced techniques in order to consider these imperfections in a buckling analysis. A deterministic buckling analysis is based on the use of the so-called knockdown factors, which specifies the reduction of the buckling load of the perfect shell in order to account for the inherent uncertainties in the geometry. In this paper, it is shown that these knockdown factors are overly conservative and that the fields of probability and statistics provide a mathematical vehicle for realistically modeling the imperfections. Furthermore, the influence of different types of imperfection on the buckling load are examined and validated with experimental results.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Weiyi Qian ◽  
Mingqiang Yin

This paper researches portfolio selection problem in fuzzy environment. We introduce a new simple method in which the distance between fuzzy variables is used to measure the divergence of fuzzy investment return from a prior one. Firstly, two new mathematical models are proposed by expressing divergence as distance, investment return as expected value, and risk as variance and semivariance, respectively. Secondly, the crisp forms of the new models are also provided for different types of fuzzy variables. Finally, several numerical examples are given to illustrate the effectiveness of the proposed approach.


2007 ◽  
Vol 13 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Marta Kosior-Kazberuk ◽  
Małgorzata Lelusz

Based on experimental results, mathematical models were elaborated to predict the development of compressive strength of concrete with fly ash replacement percentages up to 30 %. Strength of concrete with different types of cement (CEM I 42.5, CEM I 32.5, CEM III 32.5), after 2, 28, 90, 180 days of curing, have been analysed to evaluate the effect of addition content, the time of curing and the type of cement on the compressive strength changes. The adequacy of equations obtained was verified using statistical methods. The test results of selected properties of binders and hardened concrete with fly ash are also included. The analysis showed that concrete with fly ash is characterised by advantageous applicable qualities.


2021 ◽  
Vol 94 (5) ◽  
Author(s):  
György Szabó ◽  
Balázs Király

AbstractTwo-person games are used in many multi-agent mathematical models to describe pair interactions. The type (pure or mixed) and the number of Nash equilibria affect fundamentally the macroscopic behavior of these systems. In this paper, the general features of Nash equilibria are investigated systematically within the framework of matrix decomposition for n strategies. This approach distinguishes four types of elementary interactions that each possess fundamentally different characteristics. The possible Nash equilibria are discussed separately for different types of interactions and also for their combinations. A relation is established between the existence of infinitely many mixed Nash equilibria and the zero-eigenvalue eigenvectors of the payoff matrix.


Author(s):  
V.S. Khoroshilov

The research presented in the article is of cutting-edge importance because it proves the necessity to develop prognostic mathematical models with the view to studying the behavior of high-head dams for identifying the regularities of their deformations development process and thus providing quantitative definition for the set criteria values of the diagnostic indices to ensure safe operation of such structures. The paper focuses on the peculiarities of building prognostic mathematical models of the dynamic type on the basis of recurrent equations of the 1stand 2ndorders of different types depending on the order of the mathematical model, number of the principal acting factors and discreteness of the input data, with decorrelation of the input actions and sequence of transport delay introduction. It is shown that the properties of the recurrent equation solution in the form of two first conditional moment generating functions of the displacement process of the observed points in the structure delineate a prognostic model which allows predicting the displacements of the observed points. The paper describes the sequence of estimation stages during the creation of prognostic mathematical models in respect to the character of the predictive problem for various time periods of the structure operation. Different combinations of input actions and discreteness of input data, as well as their decorrelation, have been used. We also applied transport delay in order to correctly consider the inertial delay of the dam under different loads. To account for the residual part of the inertial delay, which is affected by random and unaccounted for factors, we used the autoregression model of the process development regularity. To determine the order of the autoregression model, we calculated asymptotically unbiased ratings of the correlation function for the residual error as a difference between the actual and predicted displacements. Methodological specifics of constructing prognostic models have been established in the context of the factors above. Prognostic mathematical models of different types have been developed for the selected period of the dam operation and the results of prediction have been discussed.


2000 ◽  
Vol 176 ◽  
pp. 85-86
Author(s):  
Ivan L. Andronov

AbstractA synopsis of mathematical models describing different types of variability and their application to some classes of stars is given.


2020 ◽  
pp. 143-160
Author(s):  
Sonia Kéfi

Ecological systems are undeniably complex, including many species interacting in different ways with each other (e.g., predation, competition, facilitation, parasitism). One way of visualizing, describing, and studying this complexity is to represent them as networks, where nodes are typically species and links are interactions between these species. The study of these networks allows understanding of the rules governing the topology of their links, and assessing how network structure drives ecological dynamics. Studies on different types of ecological networks have suggested that they exhibit structural regularities, which in turn affect network dynamics and resilience to perturbations. Although the use of networks to represent ecological communities dates back to the early stages of the discipline, the last two decades have seen rapid progresses in our understanding of ecological networks, as data are collected at a faster rate and better resolution, as metrics are continuously developed to better characterize network structure and as numerical simulations of mathematical models have allowed investigating how network structure and dynamics are related in more comprehensive and realistic ecological networks. This chapter describes some of the recent developments and challenges related to the study of ecological networks. After defining networks in general, and ecological networks more specifically, recent results regarding the structure of different types of ecological networks, and what is known about their dynamics and resilience, are presented.


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