Reconstructing the parameters of geofields taking measurement noise into account. Part I. Techniques for smoothing,filtration, and regularization

Various methods of interpolation (approximation, smoothing, and filtering types) which take measurement noise into account (piecewise polynomial approximation, smoothing splines, kriging, filters, etc.) are analyzed. It is found that regularization methods are used in all of them. The advantages and disadvantages of these methods are pointed out and prospects for the use of program packages by nonspecialists in mathematics and information technology are examined. Recommendations regarding the proper choice of estimation techniques, quality criteria, and parameters for monitoring them are made in the case where geofields are to be approximated and modelled.     

Ceramic piezocomposites: modeling, technology, and characterization

A comprehensive review of microstructure peculiarities, mathematical models, methods of fabrication and measurements, as well as systematic experimental data for different types of ceramic piezocomposites is presented. New families of polymer-free ceramic piezocomposites (composites ceramics/ceramics and ceramics/crystals) with properties combining better parameters of PZT, PN type ceramics, and 1-3 composites are introduced. New damped-by-scattering ceramic piezocomposites, characterized by previously unachievable parameter combinations, are proposed. New material design concepts and fabrication methods for ceramic piezocomposites are considered. Piezoelectric resonance analysis methods for automatic iterative evaluation of complex material parameters, together with the sets of complex constants for different ceramic piezocomposites, are presented. Microstructural and physical mechanisms of losses and dispersion in ceramic piezocomposites, as well as technological aspects for their large-scale manufacture and application in ultrasonic devices are considered.     

Application of the method of initial parameters to analysis of coupled hydromechanical vibrations in piping systems. Part 2. Natural frequencies and modes of coupled hydromechanical vibrations of fluid transported in pipelines

The paper presents a modification of the method of initial parameters as employed to allow for harmonic vibrations of a fluid transported in piping. The existing parameters that describe mechanical vibrations of piping are supplemented with the parameters representing the fluid displacement and pressure pulsation. For these hydrodynamic parameters the authors have derived equations of coupling within the design elements and equations of conjugation of parameters at the boundaries between the elements. Equations of conjugation of hydrodynamic and mechanical parameters are derived which allow for their mutual influence and make it possible to analyze the coupled hydromechanical vibrations. In general, the algorithm of the method of initial parameters and the method for constructing a design model have remained unchanged. Some examples are presented which demonstrate the accuracy of the proposed methods as used for the analysis of natural and forced vibrations of a fluid in a pipeline, with and without mutual influence of the fluid and the pipe.     

Upgrading Radio-Frequency Electromagnetic Field Standards. Part 1

Stages are considered in incorporating the radio-frequency range in setting up standards for electromagnetic field parameters. The problems involved are discussed, together with methods and results from resolving them. The history of electromagnetic field standards is closely related to researches in two metrological centers: VNIIFTRI and NIST.     

Mechanical State Analysis of Load-Bearing Systems. Part 1. The Ultimate State

The study presents fundamentals of the ultimate state theory for the load-bearing systems operating under complex loading (mechanical fatigue, friction and wear, temperature, electrochemical corrosion). Energy criteria of the ultimate state and methods for calculating its parameters are proposed. Strength conditions taking into account both cyclic and contact loads have been set.     

Image recognition in the presence of non-Gaussian noise with unknown statistics.

We design receivers to detect a known pattern or a reference signal in the presence of very general and non-Gaussian types of noise. Three sources of input-noise degradation are considered: additive, multiplicative, and disjoint background. The detection process involves two steps: (1) estimation of the relevant noise parameters within the framework of hypothesis testing and (2) maximizing a certain metric that measures the likelihood of the target being at a given location. The parameter estimation portion is carried out by moment-matching techniques. Because of the number of unknown parameters and the fact that various types of input-noise processes are non-Gaussian, the methods that are used to estimate these parameters differ from the standard methods of maximizing the likelihood function. To verify the existence of the target at a certain location, we use l(p)-norm metric for p > or = 0 to measure the likelihood of the target being present at the location of interest. Computer simulations are used to show that for the images tested here, the receivers designed herein perform better than some existing receivers.     

Sensitivity analysis of infectious disease models: methods,advances and their application

Sensitivity analysis (SA) can aid in identifying influential model parameters and optimizing model structure, yet infectious disease modelling has yet to adopt advanced SA techniques that are capable of providing considerable insights over traditional methods. We investigate five global SA methods—scatter plots, the Morris and Sobol’ methods, Latin hypercube sampling-partial rank correlation coefficient and the sensitivity heat map method—and detail their relative merits and pitfalls when applied to a microparasite (cholera) and macroparasite (schistosomaisis) transmission model. The methods investigated yielded similar results with respect to identifying influential parameters, but offered specific insights that vary by method. The classical methods differed in their ability to provide information on the quantitative relationship between parameters and model output, particularly over time. The heat map approach provides information about the group sensitivity of all model state variables, and the parameter sensitivity spectrum obtained using this method reveals the sensitivity of all state variables to each parameter over the course of the simulation period, especially valuable for expressing the dynamic sensitivity of a microparasite epidemic model to its parameters. A summary comparison is presented to aid infectious disease modellers in selecting appropriate methods, with the goal of improving model performance and design.     

Application of sensitivity analysis in extension,inflation, and torsion of residually stressed circular cylindrical tubes

This paper deals with applying two main sensitivity analysis (SA) methods, namely, the Sobol method and the Fourier Amplitude Sensitivity Test (FAST) method on the problem of mixed extension, inflation, and torsion of a circular cylindrical tube in the presence of residual stress. The mechanical side of the problem was previously proposed by Merodio & Ogden (2016). The input parameters in the form of the initial cylinder geometry, the amount of the residual stress, the azimuthal stretch, the axial elongation, and the torsional strain are distributed according to three probability distribution methods, namely the uniform, the gamma, and the normal distribution. In the present work, through applying Sobol and FAST methods, the most influential factors among input parameters on the output variable have been determined. The assessment of our results is then determined by the computation of bias and standard deviation of Sobol and FAST indices for each input parameter in the model.     

Thermal,Mechanical, and Diffusion Processes in Nonconducting Bodies in Periodic External Magnetic Fields

By the methods of similarity theory and dimensional analysis, the set of equations of magnetothermomechanical diffusion for nonconducting ferrite bodies is reduced to the dimensionless form. We perform the quantitative analysis of typical dimensionless criteria for the diffusion of carbon in nickel–zinc spinel. The phenomena for which typical dimensionless parameters are much smaller than one are neglected. The well-known quasistatic approximation of the equations of electrodynamics is justified.     

(Y vs. X) or (log Y vs. X)?

The problem of choosing between the models Y = α + βX and log Y = α + βX is considered. The maximum likelihood method of Box and Cox is compared with the method of using correlation coefficients to make the choice between the two models. The methods are applied to some data from the field of metallurgy. Operating characteristics of the two methods are estimated by simulation. Over a wide range of parameters there is not much difference between the two methods, although there are parameter values for which the correlation method appears markedly inferior to the likelihood method. The likelihood method seems preferable in that it is based on a probability model; this enables the statistician to make a confidence statement about the choice of model.     

Composite multivariate quality control using a system of univariate, bivariate, and multivariate quality control rules.

We propose a composite multivariate quality control (CMQC) system to control simultaneously measured variables. This system is designed to detect unacceptable trends and systematic error in one or more variables, unacceptable random error in one or more variables, and unacceptable changes in the correlation structure in any pair of variables. It is also designed to be tolerant of missing data, to be capable of rejecting as few as one or as many as all variables in a run, and to provide the analyst with control statistics and graphics that logically relate to sources of analytical error. Quality control rules for univariate, multivariate, and correlation conditions are incorporated in the system, as are plots displaying CMQC statistic values and control limits for univariate, multivariate, and correlation parameters. We also discuss advantages of the CMQC over the T2 and principal component multivariate quality control methods. We demonstrate the CMQC procedure using data from a laboratory process in which 40 variables were measured during 40 characterization runs and 23 runs analyzing unknowns.     

A brief history of mathematical ship-squat prediction, focussing on the contributions of E.O. Tuck

This article traces the contributions of Prof. E.O. Tuck to the field of mathematical ship-squat prediction. The review expands on Tuck??s own review of his early work (Ann. Rev. Fluid Mech. 10:33, 1978) and describes the use of his formulae in modern squat-prediction methods. A method for calculating Tuck??s sinkage and trim coefficients using easily obtainable ship parameters is also described.     

Calculating semiconductor parameters based on measuring electrical and thermophysical,galvanic and thermomagnetic effects using the method of varying the influence factors

The methods and the sequence for calculating the semiconductor parameters using the results of measuring the effects of a single experiment are examined. Algorithms for calculating the primary and secondary semiconductor parameters are proposed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 3, pp. 470–476, March, 1978.     

Characteristics of grating-assisted couplers.

Characteristics of grating-assisted coupling between two parallel waveguides are analyzed. The influence of the grating parameters, such as groove depth, duty cycle, and refractive indices is considered. Chirped and parallel gratings as well as gratings with sinusoidal envelope periodicity are also addressed. The analysis is based on a unified coupled-mode formalism, with the transfer-matrix method as a general solution technique. It is shown how to modify the grating parameters to provide a specific spectral response (reflectivity and transmission coefficients). As an example, two parallel gratings are used to obtain a similar response to a single grating of double length. The location of the grating between the two waveguides as well as the light-wave injection direction are very important. The presented methods and effects may be useful for design and analysis in the fields of optical communications, sensing, and processing.     

Elastic, structural, bonding, and defect properties of zinc-blende BN, AlN, GaN, InN and their alloys

Simple tight-binding simulations, incorporating only the Herman–Skillman atomic term values, are shown to provide valuable information about the bonding, elastic and structural properties of zinc-blende group III-nitrides. Our calculated values of the elastic parameters (viz., bulk modulus, elastic stiffness constants, Kleinman's internal displacement parameter, Keating force constants, etc.) for BN, AlN, GaN, and InN are shown to exist well within the range of values derived from more sophisticated methods. Despite the crude approximations used, the tight-binding method has clearly provided the meaningful trends to the local distortions around isoelectronic impurities and has described reasonably well the bond length variations as a function of composition in ternary alloys.     

Methods of researching thermophysical parameters and phenomena by means of nonstationary-frequency measurements. Part 2. Step and instantaneous heating methods

Various types of instantaneous and stepped heat source are considered, which act in unbounded bodies. A method has been devised for using the solutions to define the thermophysical parameters by means of nonstationary-frequency measurement methods.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 2, pp. 243–250, August, 1988.     

Two-phase multicomponent mass transport in a descending,straight-through flow of phases

The parameters of combined, multicomponent mass transport in a two-phase gas (vapor)-liquid system moving as a descending, laminar straight-through flow are investigated theoretically, and methods for calculating them are proposed. The methods are based on solving the system of differential equations for multicomponent convective diffusion in both phases with an allowance for the conjugation conditions at interface. The diffusion equations are solved both numerically and analytically in the boundary-layer approximation. The development of the process over large lengths of the contact device is investigated, and the asymptotic values of the component concentrations are determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 59, No. 1, pp. 99–109, July, 1990.     

Diagnostics of Flows of Pulsed Plasma by Probe, Microwave, and Photometric Methods

The methodology is suggested of complex diagnostics of pulsed plasma flows, which is based on a synchronous application of the probe, microwave, and photometric methods. The space-time distribution of the basic kinetic parameters are given under conditions of expansion of plasma clusters in vacuum and their interaction with an obstacle.     

Nanoparticles in ambient air. measurement methods

Methods for the measurement of the parameters of aerosol particles with the use of an analyzer based on the differential mobility of nanoparticles and with a diffusion aerosol spectrometer are described and tested. A comparison of the results of measurements of the diameters of nanoparticles by the two methods is performed. Results of inter-laboratory comparisons of the analyzers based on the differential mobility of nanoparticles and studies of the electric motors of household appliances which are generators of the aerosols of nanoparticles with dimensions in the range 6–50 nm are presented.     

Thermodynamic instabilities in machining processes. II. Numerical investigation of stability

A numerical investigation of methods that intensify machining by additional mechanical and thermal actions is performed. Criteria describing the formation of stagnant dissipative structures with thermodynamic instabilities of the technological system and a calculation procedure for machining regimes that ensures stable parameters of the process are proposed.Polotsk State University, Novopolotsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 146–153, July–August, 1994.