Interethnic Interactions: Expectancies, Emotions, and Behavioral Intentions

Two studies examine Hispanic and non-Hispanic White people's responses to interethnic interactions. Consistent with previous findings regarding White/Black interactions, participants who had negative expectations about intergroup interactions reported more anger and anxiety about interethnic interactions. These negative emotional responses, in turn, were associated with negative behavioral intentions such as the desire to avoid interethnic interactions and the externalization of blame if an interethnic interaction did not go well. Across the studies, White participants who were angry about interethnic interactions wanted to avoid these interactions, whereas anxiety was the key predictor of avoidance for the Hispanic participants. Results are discussed in terms of their implications for developing models of intergroup interactions and designing approaches to improve these interactions

Is emigration worth the trouble? Satisfaction with life, group identifications, perceived discrimination, and socio-economic status of immigrants and stayers

In the present study, we examined satisfaction with life (SWL), group identifications, perceived discrimination, and socio-economic status among immigrants and stayers. The study had two main objectives: 1) to test the morbidity and salutary hypotheses of immigration by comparing the psycho-social characteristics of immigrants and stayers; 2) to test a resource model of well-being among immigrants and stayers by investigating the effect of different resources and stressors on SWL. The study was conducted using a random representative sample of first-generation immigrants from the Former Soviet Union to Israel (n = 400) and a not-random large and geographically dispersed sample of Jews staying in Russia (n = 935). The comparison of immigrants and stayers revealed that immigration is a mixed blessing, salutary in some aspects and onerous in others. In general, immigrants were more satisfied with their life than stayers. In addition, identification with the country of residence was stronger among immigrants than stayers. However, immigrants reported a higher level of perceived discrimination, and their socio-economic status was lower than that of stayers. Socio-economic status, identification with the country of residence, and perceived discrimination were directly connected to SWL among immigrants and stayers. In addition, among stayers, identification with the ethnic minority group was connected to SWL, while among immigrants, identification with the country of origin was not connected to SWL. Socio-economic status and perceived discrimination also affected SWL indirectly, through their connections to identification with the country of residence among immigrants and stayers and through their connection to ethnic identification among stayers. © 2020 Elsevier LtdThe study was partly supported by a grant from Leonid Nevzlin Research Center for Russian and East European Jewry at the Hebrew University of Jerusalem . Israel Science Foundation Grant 244/15

Variable density flow in porous media

We review the state of the art in modeling of variable-density flow and transport in porous media, including conceptual models for convection systems, governing balance equations, phenomenological laws, constitutive relations for fluid density and viscosity, and numerical methods for solving the resulting nonlinear multifield problems. The discussion of numerical methods addresses strategies for solving the coupled spatio-temporal convection process, consistent velocity approximation, and error-based mesh adaptation techniques. As numerical models for those nonlinear systems must be carefully verified in appropriate tests, we discuss weaknesses and inconsistencies of current model-verification methods as well as benchmark solutions. We give examples of field-related applications to illustrate specific challenges of further research, where heterogeneities and large scales are important

Particle Methods for Simulation of Subsurface Multiphase Fluid Flow and Biogeological Processes

Abstract A number of particle models that are suitable for simulating multiphase fluid flow and biogeological processes have been developed during the last few decades. Here we discuss three of them: a microscopic model -molecular dynamics; a mesoscopic model -dissipative particle dynamics; and a macroscopic model -smoothed particle hydrodynamics. Particle methods are robust and versatile, and it is relatively easy to add additional physical, chemical and biological processes into particle codes. However, the computational efficiency of particle methods is low relative to continuum methods. Multiscale particle methods and hybrid (particle-particle and particle-continuum) methods are needed to improve computational efficiency and make effective use of emerging computational capabilities. These new methods are under development Introduction The computational methods used to simulate single-and multi-phase fluid flow can be divided into two general classes: continuum methods and particle methods. Hybrid particle-continuum methods have also been developed, and some models, such as smoothed particle hydrodynamics and lattice Boltzmann models, can be considered to be either continuum or particle methods. Particle models that can be used to simulate single-and multi-phase fluid dynamics include lattice gas model

Particle methods for simulation of subsurface multiphase fluid flow and biogeological processes

A number of particle models that are suitable for simulating multiphase fluid flow and biogeological processes have been developed during the last few decades. Here we discuss three of them: a microscopic model - molecular dynamics; a mesoscopic model - dissipative particle dynamics; and a macroscopic model - smoothed particle hydrodynamics. Particle methods are robust and versatile, and it is relatively easy to add additional physical, chemical and biological processes into particle codes. However, the computational efficiency of particle methods is low relative to continuum methods. Multiscale particle methods and hybrid (particle–particle and particle–continuum) methods are needed to improve computational efficiency and make effective use of emerging computational capabilities. These new methods are under development

Numerical Comparison of Cusum and Shiryaev-Roberts Procedures for Detecting Changes in Distributions

The CUSUM procedure is known to be optimal for detecting a change in distribution under a minimax scenario, whereas the Shiryaev-Roberts procedure is optimal for detecting a change that occurs at a distant time horizon. As a simpler alternative to the conventional Monte Carlo approach, we propose a numerical method for the systematic comparison of the two detection schemes in both settings, i.e., minimax and for detecting changes that occur in the distant future. Our goal is accomplished by deriving a set of exact integral equations for the performance metrics, which are then solved numerically. We present detailed numerical results for the problem of detecting a change in the mean of a Gaussian sequence, which show that the difference between the two procedures is significant only when detecting small changes.Comment: 21 pages, 8 figures, to appear in Communications in Statistics - Theory and Method

Kelvin-Helmholtz instabilities in Smoothed Particle Hydrodynamics

In this paper we investigate whether Smoothed Particle Hydrodynamics (SPH), equipped with artificial conductivity, is able to capture the physics of density/energy discontinuities in the case of the so-called shearing layers test, a test for examining Kelvin-Helmholtz (KH) instabilities. We can trace back each failure of SPH to show KH rolls to two causes: i) shock waves travelling in the simulation box and ii) particle clumping, or more generally, particle noise. The probable cause of shock waves is the Local Mixing Instability (LMI), previously identified in the literature. Particle noise on the other hand is a problem because it introduces a large error in the SPH momentum equation. We also investigate the role of artificial conductivity (AC). Including AC is necessary for the long-term behavior of the simulation (e.g. to get $\lambda=1/2, 1$ KH rolls). In sensitive hydrodynamical simulations great care is however needed in selecting the AC signal velocity, with the default formulation leading to too much energy diffusion. We present new signal velocities that lead to less diffusion. The effects of the shock waves and of particle disorder become less important as the time-scale of the physical problem (for the shearing layers problem: lower density contrast and higher Mach numbers) decreases. At the resolution of current galaxy formation simulations mixing is probably not important. However, mixing could become crucial for next-generation simulations.Comment: 16 pages, 23 figures, accepted for publication in MNRA

Diagnostics of rolling bearings for auxiliary electromotors of electric locomotive using parametric model and envelope spectrum

Демонструється можливість діагностування пошкоджень роликових підшипників авторегресійною (АР) моделлю для підрахунку АР коефіцієнтів з подальшим використанням АР фільтра, що вибілює і спектра обвідної для виділення ознак початкових пошкоджень. Для діагностування роликових підшипників кочення використовується АР модель для глибшого аналізу властивостей сигналу з імпульсними складовими. Інформаційний критерій Екейкі використовується для правильного обрання порядку АР моделі. АР коефіцієнти обчислюються за виразом Юла-Уокера. Виявлена низька ефективність спектральної щільності потужності параметричної моделі й наводяться переваги АР фільтра, що вибілює. Експериментальні дослідження вібраційних характеристик корпусу допоміжного двигуна встановили частотний діапазон 5,5 — 7 кГц в якому проявляється підшипникова вібрація і який можна використовувати для подальшого виділення спектра обвідної вібрації. Результати демонструють здатність АР фільтра виділяти риси не тільки пошкоджень внутрішнього, зовнішнього кілець, роликів підшипника, а також пошкоджень сепаратора, чиї ознаки ідентифікуються на спектрі обвідної відразу після застосування АР фільтра.Goal: increase of efficiency for diagnostics of rolling bearing faults using an autoregressive model to calculate AR coefficients and further application of pre-whitening AR filter and envelope spectra to extract weak faults signs. Method of doing research: diagnostics of rolling bearing faults involves signal acquisition technique and application of the AR model for better analysis of short duration signal properties and impulses. The Akaike information criterion is used to ensure optimum adaptation of AR coefficients to a fault bearing. The AR coefficients are defined with Yule-Walker equitation. The advantages of pre-whitening AR filter are presented due to the low efficiency regarding the power spectral density of the parametric model. The experimental study of vibration characteristics of the auxiliary electromotor body of electric locomotive defines the frequency band 5,5 — 7 kHz with the rolling bearing vibration, and this frequency band can be used for further extraction the envelope spectra. Value: the research shows a capability of the pre-whitening AR model to store valuable information not only about different faults concerning outer, inner race, rollers of bearings but also about the technical condition of the cage, the signs of which are displayed on the envelope spectra directly after the AR filter.Демонстрируется возможность диагностирования повреждений роликовых подшипников с использованием авторегрессионной (АР) модели для подсчета АР коэффициентов с дальнейшим применением обеляющего АР фильтра и спектра огибающей для выделения признаков начальных повреждений. Для диагностирования роликовых подшипников качения используется АР модель для лучшего анализа свойств сигнала с импульсными составляющими. Информационный критерий Экейки используется для правильного выбора порядка АР модели. АР коэффициенты вычисляются с помощью выражения Юла-Уокера. В связи с низкой эффективностью спектральной плотности мощности параметрической модели демонстрируются преимущества обеляющего АР фильтра. Экспериментальные исследования вибрационных характеристик корпуса вспомогательного двигателя определили частотный диапазон 5,5 — 7 кГц в котором проявляется подшипниковая вибрация и который можно использовать для дальнейшего выделения спектра огибающей. Исследования определяют возможность обеляющего АР фильтра хранить ценную информацию не только о разных повреждениях внутреннего, внешнего колец, роликов подшипника, а также о состоянии сепаратора, признаки которого проявляются на спектре огибающей сразу после АР фильтра