Predicting vortex-induced vibration from driven oscillation results

Two-dimensional simulations of flow past both an elastically-mounted cylinder and an externally-driven oscillating cylinder were performed at a Reynolds number of Re = 200. The results were compared to determine if the oscillations of the driven-oscillation model were consistent with the oscillations observed in the elastically-mounted system. It was found that while this is the case, there is considerable sensitivity to input forcing. This sensitivity could explain observed discrepancies between experimental results for the two systems.     

On saddlepoints of two-person zero-sum games with applications to data verification tests

A set of sufficient conditions for the existence of saddlepoint strategies of two-person zero-sum games is given which may be described as follows: The set of pure strategies for one of the two players is a compact metric space. His opponent has a best answer to each randomized strategy. The payoff function satisfies a continuity condition concerning the weak convergence of probability measures. These conditions are neither covered by those of well known existence theorems for saddlepoints nor do they generalize them. They are applied to treat important practical problems that have not been solved before. Received November 1995/Revised version August 1998     

Computational methods for comparing two binary diagnostic tests in the presence of partial verification of the disease

In the presence of partial verification of the disease, confidence interval estimation for the difference of sensitivities and specificities cannot be carried out by applying confidence intervals for the difference of binomial proportions, and the comparison of the accuracy of the two binary tests cannot be carried out by applying McNemar’s test. In this article we propose two methods for comparing the accuracy of two binary tests in the presence of partial verification of the disease. The first method is based on the application of the EM and SEM algorithms, and the second method consists of the calculation of confidence intervals for the difference in sensitivities and specificities applying confidence intervals for the difference in the two binomial proportions from the last table obtained applying the EM algorithm. We carried out simulation experiments in order to study and compare the coverage of several confidence intervals for the difference of the sensitivities and specificities.     

Methods of analyzing the results of long-time strength tests on synthetic materials

This article examines the deviations of Zhurkov's long-time strength equation, obtained in processing test results, from experimental data with reference to the example of polyvinyl chloride film. As a possible approximation an inverse linear dependence of the coefficient on temperature is proposed which makes it possible to obtain close agreement with experiment and complete information on the long-time strength of a polymer material from tests at two temperatures.Mekhanika Polimerov, Vol. 1, No. 6, pp. 92–97, 1965     

Dual divergence estimators and tests: Robustness results

The class of dual ?-divergence estimators (introduced in Broniatowski and Keziou (2009) [5]) is explored with respect to robustness through the influence function approach. For scale and location models, this class is investigated in terms of robustness and asymptotic relative efficiency. Some hypothesis tests based on dual divergence criteria are proposed and their robustness properties are studied. The empirical performances of these estimators and tests are illustrated by Monte Carlo simulation for both non-contaminated and contaminated data.     

Upper–lower class tests and frequency results along subsequences

We characterize, by means of an integral test, the upper and lower classes associated with the law of the iterated logarithm for subsequences. We also prove strong laws for the frequency of indices in connection with the lower class.     

Comparative analysis of the power of goodness-of-fit tests for near competing hypotheses. I. The verification of simple hypotheses

Using statistical modeling methods, we analyze the power of a series of goodness-of-fit tests for simple and complex hypotheses. The estimates we give for the power of the tests for simple hypotheses versus some near competing hypotheses enable us to rank the goodness-of-fit tests.     

Statistical analysis of the results of humidity-temperature tests of glass reinforced plastics (GRP)

The effect of moisture and temperature factors on the strength of glass-reinforced plastics (GRP) is examined. In view of the considerable dispersion of the experimental data, a statistical method is used for analyzing the test results. The tensile strength distribution law for KAST-V glass laminate under various humidity and temperature conditions is analyzed.Mekhanika Polimerov, Vol. 1, No. 5, pp. 135–141, 1965     

Predicting the performance of extruded low-pressure polyethylene from rheological characterstics

Characteristic features of the high-elastic stalling of the melts of modern types of low-pressure polyethylene is investigated. The possibility of predicting the performance of polyethylene pipes from measurements of the following rheological characteristics is demonstrated: melt viscosity, shear-rate gradient at the outset of high-elastic stalling, swelling of the extrudate, and the amplitude of self-sustained fluctuations in shear stress.Kazan' State Technical University, Tatarstan, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 32, No. 4, pp. 558–563, July–August, 1996.     

Predicting the porosity of glass-reinforced plastics from their thermal conductivity

The effect of porosity, reinforcement ratio and specific weight on the thermal conductivity of a series of glass-reinforced plastics has been investigated. It is shown that, if the thickness, the weight characteristic (weight per square meter), and the number of layers of reinforcing fabric are known and the thermal conductivities of the components are constant, then the porosity of the glass-reinforced plastic can be predicted from its thermal conductivity. Data on the relation between the specific weight and the thermal conductivity of the glass-reinforced plastics investigated are presented.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 522–525, May–June 1971.     

Mathematical modelling of binder removal from plastically-formed engineering ceramics

A mathematical model is developed to quantify the degradation of binder used for plastic forming of ceramic components and the mass transport of the degradation products. A fully-implicit finite-difference method is used to obtain numerical solutions of a non-linear differential equation governing the degradation rate, diffusion coefficient and concentration. It is able to predict the critical linear heating rate below which defects due to boiling can be avoided. Examples are given to illustrate the use of the model to investigate the effect of ceramic powder, supporting powder bed and binder properties on the critical heating rate.Dedicated to Professor J. Crank on the occasion of his 80th birthday     

Determination of the characteristics of viscoelastic media from the data of quasi-static tests

By representing memory-influence functions in the form of generators of the Dirac -function in order to describe the relaxation processes on a small initial interval [3], formulas are constructed for determining the true characteristics of viscoelastic media from the data of quasi-static creep tests and relaxation tests by means of the irreversibility effect [2], i.e., the dependence of the relaxation processes on the initial loading conditions.Mekhanika Polimerov, Vol. 3, No. 5, pp. 803–811, 1967     

Certain results and problems from the theory of bases

This survey touches upon the following three themes: (1) the order of decrease of Fourier coefficients with respect to some orthogonal systems; (2) the order of approximation of functions in a given class by the partial sums of orthogonal series; (3) the least order of growth of the degrees of the polynomials that form a basis in C(0,1). The survey contains a discussion of the current state of some unsolved problems and the formulation of new ones.Tranlated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 170, pp. 274–284, 1989.