Inverse Coefficient Research Articles

Application of Input-Output Table for Structural Analysis of the Nation's Economy: A Case of Mongolia

The Leontief Input-Output model is a valuable tool for economics. Many economic research works are devoted to analysis of Input-Output table [1]-[5]. In this paper, we consider a separation of Copper production subsector from Mining of metal ores sector which is one of the 55 economic sectors of Input-Output Table of Mongolia. We examine impact of this subsector on other economic sectors using Input-Output table for 2016 and Physical Measurement Method of Cost Accounting [6]. We compute input coefficients of new extended matrix as well as inverse coefficients.

Studying of the stability of the flow rates wells unto errors permeability field identification under conditions of single-phase stationary fluid filtration

The problem of calculating the producing wells flow rates in a two-dimensional reservoir is considered under conditions of stationary single-phase fluid filtration. The permeability field of the reservoir is assumed to be unknown and is determined from the solution of the inverse coefficient problem. The identification of the permeability field is carried by the known values of bottomhole pressure and is reduced to the problem of minimizing the residual function.

Numerical solution of the inverse coefficient problem of filtration in a multilayer reservoir

This work proposes a computational algorithm based on the regularization method for determining the hydraulic conductivity coefficient of a layered oil reservoir. The results of hydrodynamic investigations of vertical wells, opening a layered reservoir, are used as initial information.

Numerical analysis of an inverse coefficient problem for a chemical transformation model

Inverse coefficient problems for a non-stationary chemical transformation model are considered. The objective of this work is to test an approach consisting in reducing the inverse problem to a quasi-linear matrix equation based on sensitivity operators constructed from an ensemble of independent solutions of adjoint equations. A Newton-Kantorovich-type algorithm is used to solve the thus obtained matrix equations. This approach is tested on a chemical transformation scheme with 22 species and 20 reactions. The reconstruction results are compared with several sets of unknown reaction rates according to the influence characteristics. The analysis seems to be useful for selecting sets of reaction rates that can be reconstructed by the inverse problem solution.

Design Methodology Based on the Inversion Coefficient and its Application to Inductorless LNA Implementations

The Internet of Things (IoT) entails new challenges for the development of wireless transceivers. Radio-frequency building blocks require complex design flows in order to address very different sets of specifications. This paper presents a three-step design methodology dedicated to the synthesis of RF building blocks. Based on the inversion coefficient, the proposed design methodology allows the optimization of the circuit performance for any CMOS process and any application. It is illustrated through the implementation of inductorless low-noise amplifiers (LNA) in three different CMOS nodes: 28-nm fully-depleted silicon-on-insulator (FDSOI), and 65 and 130-nm Bulk. These LNAs are dedicated to two cases of IoT applications: multi-standard and ultra low power. The proposed circuits achieve the state-of-the-art performance for all nodes and applications. Furthermore, the methodology enables an insightful comparison of the capabilities of the different CMOS nodes in terms of power consumption, noise, and bandwidth.

Inverse coefficient problems for a transport equation by local Carleman estimate

We consider the transport equation in where is a bounded domain, and discuss two inverse problems which consist of determining a vector-valued function or a real-valued function by initial values and data on a subboundary of . Our results are conditional stability of Hölder type in a subdomain D provided that the outward normal component of is positive on . The proofs are based on a Carleman estimate where the weight function depends on H.

Three-Stage Estimation of the Mean and Variance of the Normal Distribution with Application to an Inverse Coefficient of Variation with Computer Simulation

This paper considers sequentially two main problems. First, we estimate both the mean and the variance of the normal distribution under a unified one decision framework using Hall’s three-stage procedure. We consider a minimum risk point estimation problem for the variance considering a squared-error loss function with linear sampling cost. Then we construct a confidence interval for the mean with a preassigned width and coverage probability. Second, as an application, we develop Fortran codes that tackle both the point estimation and confidence interval problems for the inverse coefficient of variation using a Monte Carlo simulation. The simulation results show negative regret in the estimation of the inverse coefficient of variation, which indicates that the three-stage procedure provides better estimation than the optimal.

Strong Bending of a Beam from a Fibrous Composite, Differently Resistant to Tension and Compression

For the analysis of bending of a thin rod made of fiber composite, the generalized Euler elastic equation is used, taking into account different resistance of the material to tension and compression, the influence of transverse shear, elongation of the axis and independent rotations of the reinforcing elements relative to the matrix. Based on Newton’s method, a computational algorithm has been developed for solving the static bending problem. A method for determining phenomenological parameters of the composite has been implemented, including photographing the bending state of the rod under the action of a system of forces and couple forces, digital processing of the photography and solving the inverse coefficient problem. The method was validated by comparing the results of computations with a laboratory physical experiment. It is shown that the moduli of elasticity in tension and compression of carbon fiber composite used in the experiment, essentially differ, and that the use of equal moduli in determining bending stiffness results in a significant error in the deflection calculations

Multi-parameters identification problem for a degenerate parabolic equation

This paper investigates an inverse problem of simultaneously reconstructing the initial value and source coefficient in a degenerate parabolic equation. Problems of this type have important applications in several fields of applied science. Being different from other inverse coefficient problems in classical parabolic equations (non-degenerate), the principal coefficient in the mathematical model discussed in the paper may vanish on both extremities of the domain. On the basis of Carleman estimate, the uniqueness and conditional stability of solution for the original problem are established. Then an iteration algorithm of Landweber type is designed to obtain the numerical solution and some typical numerical experiments are also performed. Numerical results show that the proposed method is stable and the unknown coefficients are recovered quite well.

Skeletal muscles induce recruitment of Ly6C+ macrophage subtypes and release inflammatory cytokines 3 days after downhill exercise.

Macrophages are one of the most versatile cells of the immune system that can express distinct subtypes and functions depending on the physiological challenge. After skeletal muscle damage, inflammatory macrophage subtypes aid muscles to regenerate and are implicated in physical training adaption. Based on this information, this study aimed to evaluate two classic mice macrophage subtypes and determine whether some inflammatory cytokines might be involved in the muscle adaption process after exercise. For this purpose, mice were exposed to an intermittent experimental protocol of downhill exercise (18 bouts of running, each bout 5 min with a 2-min rest interval, slope -16°) and were euthanized before [control (CTRL)] and 1, 2 (D2), and 3 (D3) days after exercise. After euthanasia, the triceps brachii was harvested and submitted to protein extraction, immunostaining, and mononuclear digestion procedures. The muscle size, macrophage accumulation, and cytokines were determined. We observed an increase in the Ly6C+ macrophage subtype (P ≤ 0.05) in D2 and D3 compared with CTRL, as well as a significant inverse correlation coefficient (-0.52; P ≤ 0.05) between Ly6C+ and Ly6C- macrophage subtypes. Moreover, we also observed elevation in several cytokines (IL-1β, IFN-γ, TNF-α, IL-6, and IL-13) at D3, although not IL-4, which tended to decrease at this time point (P = 0.06). Downhill exercises preferentially recruited Ly6C+ macrophages with important proinflammatory cytokine elevation at D3. Moreover, despite the elevation of several cytokines involved with myogenesis, an increase in IL-6 and IL-13, which potentially involve muscle adaption training after acute exercise, was also observed.

Symmetry of deterministic ratchets.

We consider the overdamped motion of a Brownian particle in an unbiased force field described by a periodic function of coordinate and time. A compact analytical representation has been obtained for the average particle velocity as a series in the inverse friction coefficient, from which follows a simple and clear proof of hidden symmetries of ratchets, reflecting the symmetry of summation indices of the applied force harmonics relative to their numbering from left to right and from right to left. We revealed the conditions under which (i) the ratchet effect is absent; (ii) the ratchet average velocity is an even or odd functional of the applied force, whose dependences on spatial and temporal variables are characterized by periodic functions of the main types of symmetries: shift, symmetric, and antisymmetric, and universal, which combines all three types. These conditions have been specified for forces with those dependences of a multiplicative (or additive-multiplicative) and additive structure describing two main ratchet types, pulsating and forced ratchets. We found the fundamental difference in dependences of the average velocity of pulsating and forced ratchets on parameters of spatial and temporal asymmetry of potential energy of a particle for systems in which the spatial and temporal dependence is described by a sawtooth potential and a deterministic dichotomous process, respectively. In particular, it is shown that a pulsating ratchet with a multiplicative structure of its potential energy cannot move directionally if the energy is of the universal symmetry type in time; this restriction is removed in the inertial regime, but only if the coordinate dependence of the energy does not belong to either symmetric or antisymmetric functions.

Class of Analytic Functions Defined by q-Integral Operator in a Symmetric Region

The aim of the present paper is to introduce a new class of analytic functions by using a q-integral operator in the conic region. It is worth mentioning that these regions are symmetric along the real axis. We find the coefficient estimates, the Fekete–Szegö inequality, the sufficiency criteria, the distortion result, and the Hankel determinant problem for functions in this class. Furthermore, we study the inverse coefficient estimates for functions in this class.

Effect of powder feeding rate on heat and mass transfer behaviors during filler powder laser welding

The heat and mass transfer behavior is the influencing factor of welding quality, during filler powder laser welding. The characteristics of plasma and keyhole can characterize the heat and mass transfer behavior. Experimental platforms were built to observe the effect of powder feeding rate on the heat and mass transfer behavior. The main results of the experiment are as follows. In the process of filler powder laser welding, the keyhole depth and fusion depth were improved by selecting the critical value of powder feeding rate 5 g/min as the welding process parameter. When the powder feeding rate exceeded the critical value, the electron temperature and electron density decreased and increased respectively. The keyhole depth decreased with the increase of the inverse bremsstrahlung absorption coefficient of the keyhole plasma at the top of the keyhole. The keyhole area increased with the increase of plasma pressure at the keyhole opening. The inverse bremsstrahlung absorption of plasma plume and the number of powder particles sprayed into the molten pool were the factors that caused the decrease of the surface temperature and the length of the molten pool.

Stability of Thin-Film Cu–As2S3 and Ag–As2S3 Structures

Thin-film Cu–As2S3 and Ag–As2S3 structures obtained by successively evaporating Cu(Ag) and As2S3 in vacuum on glass substrates have been studied. Samples of these structures have been kept in air at room temperature in the dark for 6 months, and transmission spectra have been periodically taken of these samples. The logarithm of inverse transmission coefficient in the transparency domain of As2S3 has been used as a measure that is proportional to the thickness of the metal film. It has been found that for Ag–As2S3 the thickness of the metal film varies with storage time linearly, whereas for Cu–As2S3 this dependence can be described by two different linear sections. From the decrease in metal film thickness, it has been concluded that the Ag–As2S3 structure is more stable than Cu–As2S3. It has been supposed that silver, unlike copper, does not react with As2S3 when the structures are stored in the dark, although it permanently diffuses into As2S3 during storage.

On the approximate method for determination of heat conduction coefficient

The problem of recovering a value of the constant coefficient in heat equation for one- and two-dimensional cases is considered in the paper. This inverse coefficient problem has broad range of applications in physics and engineering, in particular, for modelling heat exchange processes and for studying properties of materials and designing of engineering constructions. In order to solve the problem an approximate method is constructed; it is based on the continuous operator method for solving nonlinear equations. The advantages of the proposed method are its simplicity and universality. The last property allows to apply the method to a wide range of problems. In particular, in constructing and justifying a continuous operator method, in contrast to the Newton–Kantorovich method, the continuous reversibility of Frechet or Gato derivatives is not required. Moreover, derivatives may not exist on sets of measure zero. The application of continuous operator method to the solution of an inverse coefficient problem with a constant coefficient makes it possible to minimize additional conditions -- there is enough information about the exact solution at a single point x∗,t∗. Solving several model problems illustrates the high efficiency of the proposed method.

Logarithmic stability for a coefficient inverse problem of coupled Schrödinger equations

In this paper, we study an inverse coefficient problem for two coupled Schrödinger equations with an observation of one component of the solution. The observation is carried out in a nonempty open subset of the domain where the equations hold. A logarithmic-type stability result is obtained. The main method is based on the Carleman estimate for coupled Schrödinger equations and coupled heat equations, and the Fourier–Bros–Iagolnitzer transform.

Inverse coefficient problem for a magnetohydrodynamics system by Carleman estimates

In this article, we consider a magnetohydrodynamics system for incompressible flow in a three-dimensional bounded domain. Firstly, we state the stability results for our inverse coefficient problem. Secondly, we establish and prove two Carleman type inequalities both for the solutions and for the unknown coefficients. Finally, we complete the proofs of the stability results in terms of the above Carleman estimates.

Reconstruction for the coefficients of a quasilinear elliptic partial differential equation

In this paper we consider an inverse coefficients problem for a quasilinear elliptic equation of divergence form ∇⋅C→(x,∇u(x))=0, in a bounded smooth domain Ω. We assume that C⃗(x,p→)=γ(x)p→+b→(x)|p→|2+O(|p→|3), by expanding C⃗(x,p→) around p→=0. We give a reconstruction method for γ and b→ from the Dirichlet to Neumann map defined on ∂Ω.

One-dimensional inverse coefficient problems of anisotropic viscoelasticity

One-dimensional inverse coefficient problems of anisotropic viscoelasticity

Numerical Method for Solving the Inverse Problem of Nonisothermal Filtration

In this work a mathematical model of thermohydrodynamic processes occurring in the oil reservoir and the horizontal well bore is developed. On the basis of the proposed model and regularization methods, a computational algorithm for solving the inverse coefficient problem is proposed. Data of temperature changes, registered simultaneously by several depth gauges installed in the different locations of the horizontal part of the well bore, is taken as the initial information.