scholarly journals Single-Layer Based Algorithms for Solving the Inverse Problem of ECG

2019 ◽  
Author(s):  
Danila Potyagaylo ◽  
Mikhail Chmelevsky ◽  
Alexander Kalinin
Keyword(s):  
Inverse Problem ◽  
Single Layer

scholarly journals Quantitative method for determining the solution error of the inverse problem in the electrometry of oil and gas wells

2021 ◽  
Vol 280 ◽  
pp. 09003
Author(s):  
Mykyta Myrontsov ◽  
Oleksiy Karpenko ◽  
Volodymyr Horbulin
Keyword(s):  
Inverse Problem ◽  
Quantitative Method ◽  
Oil And Gas ◽  
Low Frequency ◽  
Single Layer ◽  
Gas Wells ◽  
Actual Measurement ◽  
Induction Logging ◽  
Oil And Gas Wells ◽  
Unstable Solutions

Determining the quantitative degree of connection between logging error and the corresponding error of oil and gas wells electrometry inverse problem solving is considered. A quantitative method to determine the magnitude of the error of solving the inverse problem depending on the magnitude of the logging error for a given model of a single layer or section as a whole is described. Examples of determining the error of the inverse problem for real well materials, taking into account the actual measurement error, are given. A method for determining the characteristics of the spatial resolution of electrometry methods is described. Examples of its use for low-frequency induction logging equipment are given. The proposed methods allow to determine the areas of equivalent solutions and the areas of existence of stable / unstable solutions of the inverse electrometry problem.

Computational Methods for the Detection of the Source of Acoustical Noise

2000 ◽  
Author(s):  
Thomas DeLillo ◽  
Victor Isakov ◽  
Nicolas Valdivia ◽  
Lianju Wang
Keyword(s):  
Inverse Problem ◽  
Computational Methods ◽  
Single Layer ◽  
Singular Value ◽  
Pressure Measurements ◽  
Single Layer Potential ◽  
Interior Region ◽  
Layer Potential ◽  
Representation Of Solutions ◽  
Value Decomposition

Abstract Computational methods for the inverse problem of detecting the source of acoustical noise in an interior region from pressure measurements in the nearfield are discussed. The methods are based on a single layer potential representation of solutions to the Helmholtz equation. Regularization is peformed using the singular value decomposition and the conjugate gradient method.

scholarly journals Cloud-Base-Height Estimation from Paired Ground-Based Hemispherical Observations

2005 ◽  
Vol 44 (8) ◽  
pp. 1221-1233 ◽  
Author(s):  
Evgueni Kassianov ◽  
Charles N. Long ◽  
Jason Christy
Keyword(s):  
Inverse Problem ◽  
Single Layer ◽  
Field Of View ◽  
Cloud Base ◽  
Lidar Data ◽  
Model Output ◽  
Sky Imager ◽  
Cloud Base Height ◽  
Surface Observations ◽  
Layer Cloud

Abstract Total-sky imager (TSI) and hemispheric-sky imager (HSI) each have a hemispherical field of view, and many TSIs are now deployed. These instruments have been used routinely to provide a time series of the fractional sky cover only. In this study, the possible retrieval of cloud-base height (CBH) from TSI surface observations is examined. This paper presents a validation analysis of a new retrieval using both a model-output inverse problem and independent, ground-based micropulse lidar data. The obtained results suggest that, at least for single-layer cloud fields, moderately accurate (within ∼0.35 km) CBH retrieval is possible.

scholarly journals Inverse Problem of Air Filtration of Nanoparticles: Optimal Quality Factors of Fibrous Filters

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Dahua Shou ◽  
Jintu Fan ◽  
Lin Ye ◽  
Heng Zhang ◽  
Xiaoming Qian ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Structural Parameters ◽  
Single Layer ◽  
Air Filtration ◽  
Quality Factors ◽  
Fibrous Filters ◽  
Lognormal Size Distribution ◽  
Face Velocity ◽  
Filter Thickness ◽  
Optimal Quality

Application of nanofibers has become an emerging approach to enhance filtration efficiency, but questions arise about the decrease in Quality factor (QF) for certain particles due to the rapidly increasing pressure drop. In this paper, we theoretically investigate the QF of dual-layer filters for filtration of monodisperse and polydisperse nanoparticles. The inverse problem of air filtration, as defined in this work, consists in determining the optimal construction of the two-layer fibrous filter with the maximum QF. In comparison to a single-layer substrate, improved QF values for dual-layer filters are found when a second layer with proper structural parameters is added. The influences of solidity, fiber diameter, filter thickness, face velocity, and particle size on the optimization of QF are studied. The maximum QF values for realistic polydisperse particles with a lognormal size distribution are also found. Furthermore, we propose a modified QF (MQF) accounting for the effects of energy cost and flow velocity, which are significant in certain operations. The optimal MQF of the dual-layer filter is found to be over twice that of the first layer. This work provides a quick tool for designing and optimizing fibrous structures with better performance for the air filtration of specific nanoparticles.

scholarly journals “In-gap” Spectroscopy: Reflected-Wave Phase and Film Characterization

2018 ◽  
Vol 63 (11) ◽  
pp. 957
Author(s):  
A. V. Turchin
Keyword(s):  
Inverse Problem ◽  
Light Wave ◽  
Single Layer ◽  
Optical Methods ◽  
Linear Matrix ◽  
Physical Parameters ◽  
Reflection Coefficients ◽  
Linear Matrix Equation ◽  
Reflected Light ◽  
Single Layer Film

Optical methods that are used to characterize the state of a surface covered with films are based on the measurement of either the ratio between the complex reflection coefficients for mutually orthogonal light polarizations (ellipsometry) or the magnitudes of reflection coefficients themselves; afterward, the parameters of films such as their number, thicknesses, and transparencies can be determined by the fitting, while solving the corresponding inverse problem. In order to extend the set of quantities that can bemeasured experimentally, a method is proposed that allows the phase of the reflected light wave to be determined, by analyzing the spectral features for light reflected from a plane-parallel gap between the surface of analyzed specimen and the environment. In particular, the spectrum obtained, by using the “moving specimen” procedure, can be transformed into the spectral dependences of the magnitude and phase of the reflection coefficient. As a result, the inverse problem of finding the dielectric permittivity of a single-layer film is reduced to the solution of a linear matrix equation, which makes the proposed method more advantageous in comparison with the ellipsometric one, for which there is no direct relationships between the ellipsometric angles and the physical parameters of the film.

Iterative Regularization Methods for Inverse Problems in Acoustics

2002 ◽  
Author(s):  
Thomas K. DeLillo ◽  
Tomasz Hrycak ◽  
Nicolas Valdivia
Keyword(s):  
Inverse Problem ◽  
Integral Equations ◽  
Conjugate Gradient ◽  
Large Scale ◽  
Three Dimensional ◽  
Gradient Methods ◽  
Optimal Solution ◽  
Single Layer ◽  
Iterative Regularization ◽  
Layer Potential

We consider the use of conjugate-gradient-like iterative methods for the solution of integral equations arising from an inverse problem in acoustics in a bounded three dimensional region. The inverse problem is the computation of the normal velocities on the boundary of a region from pressure measurements on an interior surface. The pressure satisfies the Helmholtz equation in the region. Two formulations are considered: one based on the representation of pressures by a single layer potential and the other based on the Helmholtz-Kirchhoff integral equation. Both formulations can be used to approximate the Neumann Green’s function as an alternative. The integral equations are all ill-posed and are discretized by a boundary element method. The resulting liner systems are ill-conditoned and a (smooth) regularized solutions must be sought. Two regularization rules, including a new one, for conjugate-gradient-like methods are applied and found to have advantages over a standard method based on the truncated singular value decomposition using generalized cross validation. Due to the occurence of multiple singular values for our integral operators, conjugate gradient methods compute the optimal solution in the first few iterations and prove to be particularly fast for these large scale acoustics problems.

Crystalline order to a resolution of 4.7 A in the sheath of Methanospirilium hungatii: A cross-beta structure

1984 ◽  
Vol 42 ◽  
pp. 214-215
Author(s):  
Murray Stewart ◽  
T.J. Beveridge ◽  
D. Sprott
Keyword(s):  
Cell Wall ◽  
Single Layer ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Tube Axis ◽  
Basic Subunit ◽  
Beta Structure ◽  
Diffraction Patterns ◽  
Protein Treatment ◽  
General Appearance

The archaebacterium Methanospirillum hungatii has a sheath as part of its cell wall which is composed mainly of protein. Treatment with dithiothreitol or NaOH released the intact sheaths and electron micrographs of this material negatively stained with uranyl acetate showed flattened hollow tubes, about 0.5 μm diameter and several microns long, in which the patterns from the top and bottom were superimposed. Single layers, derived from broken tubes, were also seen and were more simply analysed. Figure 1 shows the general appearance of a single layer. There was a faint axial periodicity at 28.5 A, which was stronger at irregular multiples of 28.5 A (3 and 4 times were most common), and fine striations were also seen at about 3° to the tube axis. Low angle electron diffraction patterns (not shown) and optical diffraction patterns (Fig. 2) from these layers showed a complex meridian (as a result of the irregular nature of the repeat along the tube axis) which showed a clear maximum at 28.5 A, consistent with the basic subunit spacing.

Differentiation Processes of the Ocellar Retina of the Honeybee (Apis Mellifera L.)

1990 ◽  
Vol 48 (3) ◽  
pp. 430-431
Author(s):  
Maria Anna Pabst
Keyword(s):  
Apis Mellifera ◽  
Distal Part ◽  
Cell Layer ◽  
Single Layer ◽  
Photoreceptor Cells ◽  
Distal Segment ◽  
Compound Eyes ◽  
Thin Sections ◽  
Ultrastructural Studies ◽  
Adult Worker

In addition to the compound eyes, honeybees have three dorsal ocelli on the vertex of the head. Each ocellus has about 800 elongated photoreceptor cells. They are paired and the distal segment of each pair bears densely packed microvilli forming together a platelike fused rhabdom. Beneath a common cuticular lens a single layer of corneagenous cells is present.Ultrastructural studies were made of the retina of praepupae, different pupal stages and adult worker bees by thin sections and freeze-etch preparations. In praepupae the ocellar anlage consists of a conical group of epidermal cells that differentiate to photoreceptor cells, glial cells and corneagenous cells. Some photoreceptor cells are already paired and show disarrayed microvilli with circularly ordered filaments inside. In ocelli of 2-day-old pupae, when a retinogenous and a lentinogenous cell layer can be clearly distinguished, cell membranes of the distal part of two photoreceptor cells begin to interdigitate with each other and so start to form the definitive microvilli. At the beginning the microvilli often occupy the whole width of the developing rhabdom (Fig. 1).

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

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