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Fix-position preloading, centrifugal force and higher temperatures cause the bearing units in angular contact ball bearings to expand, changing the contact load and affecting bearing life. This study aims to examine the effect of thermal and centrifugal expansion on the fatigue life of fix-position preloaded angular contact ball bearings in high-speed operating conditions.

The contact loads on the inner and outer bearing rings were resolved according to the thermal and centrifugal expansion factors in the quasi-static position preloading model. The pressure and frictional stress distribution were used to calculate the subsurface stress in the contact area, while the Zaretsky model was used to determine the relative fatigue life of the inner and outer bearing rings.

Under fix-position bearing preloading, thermal and centrifugal expansion significantly affected the contact load and relative fatigue life. At the same axial preload, the inner ring contact load was higher than the outer ring contact load, with a maximum difference of 132.3%. The decrease in the inner ring relative life exceeded the outer ring contact load, with a maximum difference of 7.5%, compared to the absence of thermal and centrifugal expansion.

This study revealed the influence of thermal and centrifugal expansion on the fatigue life of angular contact ball bearings in high-speed service conditions.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0065/

The purpose of this paper is to propose a fractal model of thermal contact conductance (TCC) of rough surfaces based on cone asperity.

A detailed numerical study is conducted to examine the effects of contact load, fractal dimensional, fractal roughness and material properties on the TCC of rough surfaces.

The results indicate that when the fractal dimension D is less than 2.5, the TCC of rough surfaces increases nonlinearly with the increase of the contact load. However, when the fractal dimension D is greater than or equal to 2.5, the TCC of rough surfaces increases linearly with the increase of the contact load; the TCC of the rough surfaces increases with the increase of the fractal dimension D and the decrease of the fractal roughness G; the material parameters also have an influence on the TCC of the rough surfaces, and the extent of the effect on the TCC is related to the fractal dimension D.

A fractal model of TCC of rough surfaces based on cone asperity is established in this paper. Some new results and conclusions are obtained from this work, which provides important theoretical guidance for further study of TCC of rough surfaces.

The Russian invasion of Ukraine in February 2022 has led to the displacement of many Ukrainians. The purpose of this study is to investigate the relationship between their contact with Dutch society and their mental health. To this end, 136 adult, mostly female, displaced Ukrainians in the Netherlands participated in an online survey to investigate the relationship between quality of host national contact and mental health, as moderated by quantity of host national contact. The survey had a Ukrainian, Russian and English version, and it consisted of single questions assessing various variables, including quality of host national contact, quantity of host national contact, amount of discrimination/prejudice as well as five questions assessing mental health (Mental Health Inventory 5 [MHI-5]; Berwick et al., 1991). Contrary to the hypotheses, no interaction was found between quality of host national contact and quantity of host national contact, and quality of host national contact did not have a significant main effect on mental health. However, there is a significant, yet nonlinear main effect of quantity of host national contact on mental health. Moreover, there is a significant correlation between quality of host national contact and quantity of host national contact. Finally, and interestingly, there is a positive relationship between the amount of discrimination/prejudice and mental health among people who chose to fill out the Ukrainian version of the survey. These results provide a nuanced view of the relationship between the host environment and mental health, and governmental policies should take into account the complexity of this relationship.

A total of 161 displaced, mostly female (90.40%), Ukrainians in the Netherlands with the average age of 35 agreed to participate in this online survey. The main variables measured were mental health (dependent variable), quality of host national contact (independent variable 1) and quantity of host national contact (independent variable 2/moderator). Additional variables, such as the level of perceived discrimination/prejudice, have been included in the analyses. The survey was available in three different languages: Ukrainian, Russian and English.

In this study, the role of host national contact in the mental health of displaced Ukrainians in the Netherlands was investigated. The results showed that there was no interaction between quality of host national contact and quantity of host national contact in the prediction of mental health. Moreover, quality of host national contact did not predict mental health. Thus, both of the (preregistered) hypotheses of this study were refuted. However, the amount of perceived discrimination/prejudice turned out to be linked to mental health. Surprisingly, the amount of perceived discrimination/prejudice predicted higher mental health scores among participants who chose to fill out the survey in Ukrainian. Moreover, of the respondents included in the analysis, 94.85% gave reason for mental health concerns, as expressed by a converted MHI-5 score below 60.

Even though this study does show a positive relationship between the level of discrimination/prejudice and mental health among displaced Ukrainians who filled out the Ukrainian version of the survey, it does not offer a definite explanation for why this seemingly unexpected result occurred. No causal conclusions can be drawn based on this study regarding the relationship between host national contact and mental health.

The results of this study show that certain occurrences in the contact with host society members relate to mental health in unexpected and seemingly complex ways. This might mean that this study has potential for nuancing the current scientific knowledge regarding the relationship between host national contact and mental health. Such nuances might be quite important, as scientific research often forms the basis for governmental policies aimed at improving the mental health of displaced people. Therefore, governmental policymakers should be aware of the fact that there is no easy, clear-cut answer yet to the complex host society factors that play a role in the mental health of various displaced groups. Moreover, an investigation of the role of host national contact might lead to valuable knowledge about factors that contribute to the mental health of refugees. As has been said, refugees are at risk of developing various mental health issues, so they might need help managing their mental health. To this end, policymakers might need evidence-based information to develop interventions targeted at specific refugee groups. By investigating the mental health of displaced Ukrainians in the Netherlands, new insights will be gained to optimize mental health care for this particular refugee group.

This study yields important information regarding the degree of participation and inclusion of displaced Ukrainians in Dutch society, which can inform policies targeted at improving the experiences of this new displaced group. Because displaced Ukrainians have to deal with the mental health consequences of war and displacement, they might be particularly in need of a safe haven in which they feel included.

To the best of the author’s knowledge, this is the first study in which the role of the host society context in the mental health of displaced Ukrainians in the Netherlands is assessed. The results are quite unexpected and can nuance the current research on the link between discrimination and mental health. Moreover, this study can inspire future research to be conducted in the reasons behind this nuance, by researching the role of identity and uncertainty. Also, the author believes that this study is particularly suitable for this journal because it really looks at the link between social inclusion in the Dutch context and mental health outcomes.

The purpose of this paper is to calculate the meshing stiffness of nutation face gear considering the roughness, establish the calculation method of time-varying meshing stiffness of rough tooth surface and analyze the influence of roughness, load and other factors on the meshing stiffness of tooth surface.

The Weierstrass–Mandelbrot (W-M) function in the Majumdar–Bhushan model is used to characterize the rough contact line of the tooth surface, the normal height and radius of the micro convex body are calculated and the contact flexibility of the contact point of the tooth surface is obtained. The contact flexibility and the bending shear deformation flexibility obtained previously are substituted into the improved deformation compatibility equation for iterative calculation, and the time-varying meshing stiffness of the nutation face gear considering the roughness is obtained.

Compared with ABAQUS finite element simulation results, it is found that the meshing stiffness curve of rough tooth surface is more gentle than that of smooth tooth surface, the meshing stiffness value is smaller and the meshing stiffness change is smaller at the position where the number of gear teeth coincide changes.

In the process of calculating contact deformation, the fractal theory W-M function is used to characterize the contact line of the rough nutation face gear, and the deformation coordination condition considering roughness is improved. Therefore, the method of time-varying meshing stiffness considering roughness can obtain more accurate results, which provides theory and data for the subsequent dynamics analysis of the nutation face gear transmission.

For contemporary American young adults (aged 18–29), coresidence with parents is now the most common living arrangement. Recent research on residential transitions out of and back into the parental home shows that residential independence is still common, meaning that many young adults coreside with parents after first leaving the nest. The timing of residential independence and subsequent coresidence is often tied to other life-course outcomes, such as relationships and employment, as well as characteristics of the family context, such as family structure and financial resources. A small body of research also demonstrates that residential transitions are common following criminal justice contact experiences such as arrests and periods of incarceration. While this association does not appear to be explained by the family context, the current study argues there are several reasons to anticipate heterogeneity in coresidence patterns based on the childhood family context. Drawing on data from the 1997 cohort of the National Longitudinal Survey of Youth, I find that criminal justice contact is associated with coresidence with parents during young adulthood in a fairly consistent manner across different dimensions of family context (although parental education may play a role). These findings demonstrate the power of the criminal justice system in directing or redirecting residential trajectories and have implications for both individuals with contact and their families.

Contact problems are central to solid mechanics as contact is the principal method of applying loads to a deformable body and the point with resulting stress concentration is often the most critical point within the body. This paper presents a finite element model for the elastic contact between two cylinders at several positions. The effects of friction and surface roughness have been considered. The contact between two skew cylinders is also investigated. Results from finite element model show a good agreement with those of analytical solutions available in the literature. It was seen that the geometry of contacting bodies and orientation of applied load effect highly on contact stresses. Although the effect of surface roughness was seen to be more than that of friction, both of them can be assumed negligible in elastic contact problems.

The purpose of this study is to propose a fractal model of thermal contact conductance (TCC) of rough surfaces considering substrate deformation. Three deformation modes of the asperity of the rough surface are considered, including elastic deformation, elastic–plastic deformation and full plastic deformation.

The influences of contact load, fractal dimension and fractal roughness on the TCC of the rough surface were studied.

The results show that the TCC of the rough surface increases with the increase of contact load. When D > 2.5, the larger the fractal dimension, the higher the increased rate of the TCC of the rough surface with the increase of contact load. The TCC of the rough surface increases with the increase of fractal dimension and decreases with the increase of fractal roughness. The TCC of the rough surface can be achieved by selecting a contact surface with roughness.

A fractal model of TCC of rough surfaces considering substrate deformation was established in this study. The achievements of this study provide some theoretical basis for the investigation of TCC of rough surfaces.

Tribeca is a predominantly wealthy, white neighborhood in New York City and is a microcosm of the service-and-information-based economy that characterizes many communities in global cities today. Tribeca residents are mostly affluent and work in high-end, service-oriented professions, consuming low-end personal services produced locally. Many of the people who provide these personal services in Tribeca are foreign-born. This chapter explores the nature of intergroup contact between native residents and immigrant service workers to understand how they navigate social boundaries of race/ethnicity, nation-of-origin, occupation, and social class.

This chapter is based on six years of ethnographic data collection and participant observation, in addition to interviews with 66 informants, including both immigrant service workers and Tribeca residents.

This research highlights the importance of local contextual factors in shaping how people perceive one another and interact. Although in Tribeca this intergroup contact fails to alter boundaries of race, class, and nation-of-origin, residents and immigrants still have meaningful interpersonal contact, which is the result of bridging, or overlooking, existing social boundaries.

The results of this research challenge the assumption that relations between natives and immigrants in stratified settings are characterized by resentment or hostility. Instead, contextual factors in Tribeca shape intergroup perceptions and contact in a way that allows for positive interpersonal, albeit largely superficial, relationships to take root.

Formal and informal interactions in the political elite and between the political elite and other actors have attracted a great deal of research (Petersson, 1996; Munk Christiansen, Möller, & Togeby, 2001; Moore, Sobieraj, Whitt, Mayorova, & Beaulieu, 2002). However, such research has mainly been concerned with the contacts of leading politicians once they have already become part of the elite, not the role that contacts might have played in their recruitment.

Extant research suggests that salespeople can significantly impact consumers’ outcome perceptions. Examines the importance of initial contact with salespeople on consumers’ perceptions of value and the impact of salesperson service failure on perceptions of value among non‐purchasers. An exit survey of shoppers was conducted to realistically study these issues. Results show that outcome perceptions were significantly lower when either there was no contact with salespeople, or the consumer had to initiate the contact. The retailer that had the highest percentage of salesperson initiated contact, earned the highest perception ratings and also had the highest ratio of buyers to browsers. Furthermore, non‐purchasers that experienced service failures (slow service or offended by a salesperson) discounted not just the perception of that retail visit, but also overall value compared to other retailers. These results suggest that retailers must encourage their sales staff to initiate consumer contact.