High water pressure is one of the primary reasons for fracture water inrush through numerous cracks at the entry points of deep tunnels. Two types of tensile shear failure modes and one type of compression shear failure mode have been established for fracture water inrush under high water pressure condition. In this study, the condition for critical water pressure for two-dimensional crack initiation

Reservoir simulator is widely known in the petroleum industry for analysing and predicting the fluid flow behaviour through porous media. Conventional mathematical approach, which is the mostly used approach in reservoir simulation, assumes several unrealistic assumptions. Introducing the memory formalism with classical mathematical approach can eliminate this shortcoming. Because, the assumptions

This article features a simple method for describing the phase equilibrium of the ternary water-salt-carbon dioxide system. At first, an iterative solution is shown using well known equations of state and solubility correlations to predict the compositions of liquid and gas phases in a saline aquifer. By virtue of several assumptions, iterations can be avoided entirely in order to use the method for

In the past few decades, evolutionary multi-objective optimization has become a research hotspot in the field of evolutionary computing, and a large number of multi-objective evolutionary algorithms (MOEAs) have been proposed. However, MOEA is still faced with the problem that the diversity and convergence of non-dominated solutions are difficult to balance. To address these problems, an efficient

Here, we model a thin layer of graphene located above a metal surface by means of a surface boundary condition in two different stencils, namely, a simple cubic grid (SC-Grid) and a body centered cubic grid (BCC-Grid). We extend the methodology described in the literature by taking into account the interband contribution of the graphene’s conductivity in addition to the intraband contribution. The

This paper deals with pricing of European and American options, when the underlying asset price follows Heston model, via the interior penalty discontinuous Galerkin finite element method (dGFEM). The advantages of dGFEM space discretization with Rannacher smoothing as time integrator with nonsmooth initial and boundary conditions are illustrated for European vanilla options, digital call and American

In this work, the q-homotopy analysis transform method (shortly q-HATM) which is a combined form of q-homotopy analysis method and Laplace transform method is employed to find numerical solution to the new modified coupled Korteweg–de Vries system. This method allows us to fine-tune the convergence region along with rate of convergence of the obtained series solution by allowing the auxiliary parameters

This paper shows the influence of the shift phase angle ψ between phase currents and back-electromotive forces on magnetic radial forces and torque ripple for a specific low power permanent magnet synchronous machine. This influence is firstly demonstrated through analytical development considering only the first harmonic values. Then, magnetic pressure harmonics versus space and frequency as well

The airway/lung mechanics is usually represented with nonlinear 0-D models based on a pneumatic-electrical analogy. The aim of this work is to provide a detailed description of the human respiratory mechanics in healthy and diseased conditions. The model used for this purpose employs some known constitutive functions of the main components of the respiratory system. We give a detailed mathematical

PI controllers are commonly used for the DC-link voltage control of single phase grid-tied inverters. This DC-link voltage is characterized by double-line frequency ripples, which are natural by-product of single phase AC systems. These ripples, if not controlled properly, can adverse the performances of the grid-tied PV system at the AC side, particularly the grid current THD. On the other hand, random

Small-signal stability of three-phase ac grid-connected converters can be analysed by using the impedance-based method in d-q frame. Based on this approach, the d-q impedance models of both source and load subsystems are represented with 2-by-2 matrices, and their ratio (known as the return ratio matrix) is used for stability assessment. This, however, requires to apply the generalized Nyquist criterion

The homogeneity problem for testing if more than two different samples come from the same population is considered for the case of functional data. The methodological results are motivated by the study of homogeneity of electronic devices fabricated by different materials and active layer thicknesses. In the case of normality distribution of the stochastic processes associated with each sample, this

Advanced numerical analysis of structures forces the massive implementation of numerical algorithms, relying on certain convergence of sequences of discrete finite element and similar approximations in spaces of integrable functions, conceding non-physical discontinuities and imperfectness to all numerical results. This is demonstrated on a model example of a thick elastic beam on the 2-parametric

In this research article, we have designed a novel image encryption scheme based on Deoxyribonucleic acid (DNA) and chaotic sequencing. We have studied sequences of different genes consisting of four bases, Adenine (A), Cytosine (C), Thymine (T) and Guanine (G), also known as nucleotides which are the fundamental code of life. The purpose of DNA is to store, copy and transmit the genetic information

Forecasting of energy-related variables is crucial for accurate planning and management of electrical power grids, aiming at improving overall efficiency and performance. In this paper, an artificial neural network (ANN)-based model is investigated for short-term forecasting of the hourly wind speed, solar radiation, and electrical power demand. Specifically, the non-linear autoregressive network with

This paper numerically demonstrates the drafting, kissing, tumbling (DKT) phenomenon between two interacting circular, impermeable particles of different sizes in a confined medium for different scenarios using Immersed Boundary (IB) method in 2D. Two cases were considered for this particular problem. In the first case, referred to as Case 1, the trailing particle was larger in size than the leading

We investigate finite amplitude stability of spatially inhomogeneous steady state of an incompressible viscoelastic fluid which occupies a mechanically isolated vessel with walls kept at spatially non-uniform temperature. For a wide class of incompressible viscoelastic models including the Oldroyd-B model, the Giesekus model, the FENE-P model, the Johnson–Segalman model, and the Phan–Thien–Tanner model

More and more applications encompass battery energy storage systems (BESSs) based on Li-ion batteries. However, when designing the power converter of a BESS or when studying the interaction between BESSs and other application components, relying on a real battery makes the process cumbersome, expensive, and time-consuming. Moreover, the battery could even suffer damages. The aim of the work is to show

In this paper, two localized meshless methods based on polynomial basis functions are utilized to solve axisymmetric problems. In the first approach, we applied the localized method of particular solutions (LMPS) and the closed-form particular solution to simplify the two-stage approach using Chebyshev polynomial as the basis functions for solving axisymmetric problems. We also propose the modified

The paper deals with mathematical modelling and the control system for UltraFast Charging Stations (UFCS) based on DC micro-grid concept and Energy Storage System Integration to feed new Electrical Vehicles (EVs) at 800V DC in order to reach the EVs power requirement for charge-time less than 10 min. The UFCS integrates a battery energy storage system (BESS) to reduce the peak power of AC main grid

In this article we propose a new more general calibration of the Heston Stochastic-Local Volatility (HSLV) model. More precisely, the main contribution is to perform the direct calibration of the whole set of parameters at the same time instead of the usual two steps procedure. Moreover, the proposed approach allows to use exotic options to calibrate the HSLV model, thus making it more flexible and

We present an optimal shape design problem of a transversely and axially loaded nonlinear stepped elastic beam with piecewise constant thickness distribution. The nonlinear beam model proposed by D.Y. Gao in 1996 is considered for modelling the state problem. The objective of the optimization is to find the thickness distribution to maximize the stiffness of the beam subjected to geometrical constraints

In this paper, by combining the operator splitting and second order modified upwind technique, the mass-preserving domain decomposition method for solving time-dependent three dimensional convection–diffusion equations is analyzed. A three steps (x−direction, y−direction and z−direction) method is used to compute the solutions over each non-overlapping sub-domains at each time interval. The intermediate

Due to certain difficulties in solving fourth-order partial differential equations (PDEs) using localized methods, the given differential equation is normally split into two decoupled second order PDEs. Such an approach is only feasible for Dirichlet and Laplace boundary conditions. In this paper the localized method of particular solutions is applied to fourth-order PDEs directly using polynomial

This study presents and compares two original high-speed protection circuit methods, namely, ig integration and vgs derivation, against short-circuit types, referred to as, the hard switch fault and fault under load. Since the gate-drain capacitor Cgd of a power device depends on the drain to source voltage vds, it can become an original native sensor to monitor the switching operation and so detect

We study a classical predator–prey system with the assumption that the birth rate of the prey is small in comparison with the death rate of the predator. As a consequence, some solutions of the system might have a slow–fast structure. Using singular perturbation technique and various scalings, we construct an approximation for the solution. Although the explicit formula for the solution is available

The operation of a dockless bicycle-sharing system is modeled by a stochastic system characterized by two kinds of interacting components, the distribution of bicycles on a sidewalk and behaviors of riders, whose simple and basic actions lead to complex results. From the model, the collective behavior emerging in the bicycle-sharing system is described by a nonlinear evolutionary equation for the density

In this manuscript, we consider an efficient dissipation-preserving finite element method for a class of two-dimensional nonlinear fractional wave equations on irregular convex domains. We show that the fully discrete method preserves the discrete energy structures under the same boundary conditions as the continuous model. Furthermore, the optimal order error estimates of the fully discrete scheme

The purpose of this paper is to consider heat and mass transfer processes on two non-Newtonian fluids (Walters-B viscoelastic and Casson fluid) situated in a hot environment. This study considered concentrated fruit juice and tomato sauce as the type of Casson fluid and polymethyl methacrylate, chromatography, and ceramic processing as the type of Walters-B viscoelastic fluids. The model is governed

Convolutional neural networks are a promising tool for solving the problem of pattern recognition. Most well-known convolutional neural networks implementations require a significant amount of memory to store weights in the process of learning and working. We propose a convolutional neural network architecture in which the neural network is divided into hardware and software parts to increase performance

With quick variations and growths in engineering technology, the activation and binary chemical reaction have sparked vast interest for engineers and scientists due to its immense applications in chemical engineering, food processing, processes of transportation, reservoir of geothermal, etc. In the energy activation, the least amount of energy is required for stimulation of reactants, wherever a chemical

The objective of this research is to design a higher order Sliding Mode Controller (SMC) for a Static Synchronous Compensator (STATCOM) and investigation of its implication on power system stability improvement. The theory of Super-Twisting–Sliding-Mode-Control (STSMC) is applied to determine the nonlinear control law of a STATCOM. The STSMC based control combines 2-sliding control and Robust Exact

In this paper, the synchronization of master–slave Lur’e systems with time-delayed feedback control is further studied. To begin with, an augmented N-dependent Lyapunov–Krasovskii functional (LKF) is designed, where some augmented vectors are chosen to complement some coupling information between the nonlinear functions and other system state variables. Next, a new delay-dependent and its derivative-dependent

In this paper, we develop parameter-robust numerical algorithms for Biot model and apply the algorithms in brain edema simulations. By introducing an intermediate variable, we derive a multiphysics reformulation of the Biot model. Based on the reformulation, the Biot model is viewed as a generalized Stokes subproblem combining with a reaction–diffusion subproblem. Solving the two subproblems together

Multiquadric (MQ) quasi-interpolation has been extensively studied in approximation theory and its applications. However, most of them only focus on the case that the sampling data are point-evaluation functionals (discrete function values). This restricts its applications since a more general form of data in real applications is integral functionals (integration of an approximand over subdomains that

Hybridization ratio α is an additional degree of freedom offered by the hybrid excitation principle in the design of synchronous electrical machines. The first goal of this contribution is to present the tool developed for analysing the effect of the hybridization ratio. This software tool is based on the electrical circuits modelling of hybrid excitation synchronous machines. This tool can also be

Predator–prey interaction is considered as a natural phenomenon in ecological system. An obvious question arises in ecosystem is that how predator affect the density of prey population. In most of the ecological models, predators reduce prey densities by direct killing which is a minor part in population dynamics. Experimental studies on vertebrate has shown that fear of predators can influence the

In this work, we introduce a useful and efficient calculation method for solving linear fractional pantograph delay equations (FPDEs). The proposed method is primarily dependent on the least-squares approximation technique. After embedding the problem into a minimization problem, it solves the Lagrange multiplier method. The convergence analysis is theoretically proved. Finally, some numerical examples

Multiphase flow equations for two components (for instance water and hydrogen) and two phases (liquid and gas), with equilibrium phase exchange, has been used to simulate the process of miscible displacement in porous media. Laboratory and field studies have shown that this assumption fails under certain circumstances especially for accurate description of the pollution and a finite transfer velocity

Implied volatility and implied vol-of-vol are two different sources of risk but the latter has been generally neglected. However, recent studies show the importance of both risk factors for investment strategies. The elasticity of vol-of-vol is focused on in this paper. We propose a revised Heston model reflecting the random nature of vol-of-vol and obtain pricing formulas of variance swaps for simple

Due to potential dynamic interactions among dc microgrid power converters, the performance of some of their control loops can vary from the designed behavior. Thus, online monitoring of different control loops within a dc microgrid power converter is highly desirable. This paper proposes the simultaneous identification of several control loops within dc microgrid power converters, by injecting orthogonal

For the analyze of forced and free vibrations of composites with periodically varying interfaces, we develop an energetic boundary function method. Three types of beams under different homogeneous boundary conditions and a sequence of boundary functions for each type beam are given, which automatically satisfy the homogeneous boundary conditions. Then we derive an energy equation and construct the

The goal of this paper is to investigate the complex nonlinear dynamics and its control chaotic behavior in electromechanical valve actuator (EVA). The nonlinear phenomena can be expressed using numerical techniques, such as time responses, phase portraits, Poincaré maps, and frequency spectra. Lyapunov exponents and Lyapunov dimensions can be used to confirm chaotic behavior. Finally, state feedback

The real time simulation is a key tool for the implementation of monitoring and diagnostic methods as well as of model-based control strategies in modern photovoltaic systems. Under the hypothesis that all the cells of the photovoltaic array operate in the same temperature and irradiance conditions and have the same degradation level, the values of the parameters appearing in the single diode equivalent

In this article, we present a new pseudospectral method to approximate the solution of one- and two-dimensional Fisher’s equations, which is a prototype of nonlinear reaction–diffusion equations. The proposed method is based on Chebyshev–Gauss–Lobatto points and employed collocation in both spatial and time direction to study of several travelling wave solutions which evolves into a shock like wavefront

In this paper, we focus on the convergence of stochastic differential equations with Markovian switching and 1∕2-Hölder continuous diffusion coefficients. We give the convergence between numerical solutions and explicit solutions at a rate of 1∕logn by the Euler–Maruyama method. Parameter estimations for CIR model with Markovian switching are obtained by the quadratic variation method and composite

This paper studies the effect of habitat complexity on Greater one-horned rhinoceros (Rhinoceros unicornis) and tiger (Panthera tigris) population model in Kaziranga National Park (KNP), Assam, India. Based on the analysis of the data collected from PCCF, Wildlife, Assam, three mathematical models are formulated and studied. In view of ecology, the main objective of the study is to increase the size

In this paper, an interval arithmetic-based method for parameters identification of a fuel cell equivalent circuit is presented. The fuel cell experimental impedance spectrum, acquired through the electrochemical impedance spectroscopy (EIS), is identified using interval-valued parameters of the fuel cell Fouquet model. The method is based on a branch-and-bound technique, further enhanced using the

In practical gene regulatory networks, function perturbation often occurs due to gene mutation. This paper studies the function perturbation impact on the stability and set stability in distribution of probabilistic Boolean networks (PBNs) by using the semi-tensor product of matrices. Firstly, the stability and set stability in distribution of PBNs is recalled and the function perturbation problem

In this paper, we propose an incredible modification of variational iteration algorithm-II that will accelerate the fast convergence of the series solution. We utilize the proposed algorithm on KdV, mKdV and combined KdV–mKdV equations to illustrate its accuracy and reliability. The consequences of modified variational iteration algorithm-II (MVIA-II) show that the proposed technique minimizes the

In this paper, we consider the linear Boltzmann equation subject to uncertainties in the initial conditions and matter parameters (cross-sections/opacities). In order to solve the underlying uncertain systems, we rely on moment theory and the construction of hierarchical moment models in the framework of parametric polynomial approximations. Such model is commonly called a generalized Polynomial Chaos

In this paper, we present the Virtual Element Method (VEM) for the solution of strongly anisotropic diffusion equations. In the VEM, the bilinear form associated with the diffusion equations is decomposed into two parts: a consistency term and a stability term. Therefore, the local stiffness matrix is the sum of two matrices: a consistency matrix and a stability matrix. Both matrices are constructed

We propose an optimal control problem to determine the best aeration strategy for aerobic biodegradation in a composting cell. The goal is to minimize the deviation of the oxygen level from its reference value for the entire duration of the biodegradation process. The mathematical model includes several chemical phenomena, like the aerobic biodegradation of the soluble substrate by means of a bacterial

The present paper investigates the role that the radial component of heat conduction plays in a cone-plate viscometer. The cone and the disk may be taken as stationary or in action; both co-rotating or counter-rotating. Hydrodynamic and thermal fields are resolved by means of computationally simulating the resulting systems of equations. Upon working out the well-documented velocity field in the gap

In this paper, we consider the dynamics of a plant disease model with a ratio-dependent state impulsive control strategy. It is shown that the boundary equilibrium point of the controlled system is globally asymptotically stable. By combining LaSalle’s invariant theorem, Brouwer’s fixed point theorem and some analysis techniques, we are able to determine the basic reproduction number, confirm the well-posedness

Differential evolution (DE) is known as a strong and simple optimization method able to work with non-differential, nonlinear, and multimodal functions. This paper proposes a modified differential evolution (MDE) algorithm for solving a high dimensional nonlinear optimization problem. The issue is finding maximum likelihood estimation (MLE) for the parameters of a non-homogeneous Poisson process (NHPP)

Uncertainty in model-based decision support is commonly addressed using mixed methods rather than a single method. Different mixes of methods result in different modelling and processes for robust decision support, and subsequently different decision outcomes. This article focuses on the notion of ‘good’ modelling practice and develops a reporting guideline to make the use of multiple methods in robust

In modelling and simulation a user performs complex sequences of tasks that are intrinsically linked in the form of networks. Tasks include simpler steps such as copying and transforming files to using mesh generation or visualisation software to create inputs or to analyse outputs. Typically, these sequences involve manual steps which are time expensive, often involve use of multiple, incompatible

Accurate predictions for radiant heat flux are necessary for determining exposure levels to personnel and infrastructure in the event of wildfires. However, detailed physics-based calculations of radiant heat flux are complex and current modelling practice involves significant simplifications in order to make these calculations tractable. We detail current practice for the calculation of radiant heat

Wildland fires can take different forms such as surface fire or an elevated crown fire or combination of both. Crown fires are normally originated from surface fires spreading either along the bark of the tree trunks or direct flame contact to low branches with leaves and needles. In the past, surface fire (grassfire) spread simulations were conducted using physics-based models with fidelity. Here