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This paper aims to examine the precision loss of ball screw raceway under different operating conditions and geometry parameters.

Based on a new coefficient K’ introduced especially for ball screws to reflect the actual contact condition, the modified Archard theory is applied to ball screws to obtain wear volume of the ball-screw contacts. Thus, the axial precision loss can be defined as the ratio of the wear volume to the contact area. Meanwhile, a novel running bench and a precision-measuring system of ball screws are conducted. Precision variation is obtained and analyzed during the whole life running test, which agrees well with the theoretical values calculated in this paper.

For a given rotational speed, the increasing rate of the precision loss rate is high at low axial load and then becomes small with the increasing axial load, whereas for a given axial load, the precision loss rate is proportional to the rotational speed. Besides, the precision loss rate is reduced with the increasing contact angle between a ball and the screw raceway, and is proportional to the helix angle when the angle changes from 1 to 10 degrees.

The rotational speed used in this experiment is low and the ball screw is of no-load type, although results calculated by the model and Wei’s model seem close when the axial load is high, whether the model built in the paper is applicable to the condition of high rotational speed and preload still needs to be verified in the future work.

This study provides an accurate model to predict the precision loss of the screw raceway and estimate the remaining life of ball screws, which is significant for better performance of ball screws as well as the computer numerical control machine tools.

Previous studies on the wear of ball screws mainly focused on the drag torque analysis and mechanical efficiency estimation, and the experiment to verify their theoretical analysis was almost all limited to the test of drag torque or axial rigidity, which is neither sufficient nor persuasive. However, in this paper, the authors proposed a comprehensive wear prediction model which combines the modified Archard wear theory, Hertz contact theory and kinematic theory of ball screws. To the best of the authors’ knowledge, this kind of study has never been reported in the literature. In addition, for the lack of the test bench and high cost of the experiment, the whole life operation test, which is designed and conducted to confirm the model in this paper, has never been reported in literature either.

This paper aims to study the relationship between normal contact stiffness and contact load. It purpose a new calculation model of the normal contact stiffness of joint surfaces by considering the elastic–plastic critical deformation change of asperities contact.

The paper described the surface topography of joint surfaces based on fractal geometry, and fractal parameters and of fractal function derived from measurement data. According to the plastic–elastic contact theory, the contact deformation characteristic of asperities was analyzed; the critical deformation estimation model was presented, which expressed critical deformation as the function of fractal parameters and contact deformation; the contact stiffness calculation model of single asperity was brought forward by considering critical deformation change.

The paper combined the surface topography description function, analyzed the asperity contact states by considering the critical deformation change, and calculated normal contact stiffness based on fractal theory and contact deformation analysis. The comparison between theoretical contact stiffness and experimental data indicated that the theoretical normal contact stiffness agreed with the experimental data, and the estimation model for normal contact stiffness was appropriate.

Owing to the possibility of plastic deformation during the loading process, the experimental curve between the contact stiffness and the contact load is nonlinear, resulting in an error between the experimental results and the theoretical calculation results.

The paper established the relationship between critical deformation and fractal surface topography by constructing asperity distribution function. The paper proposed a new normal contact stiffness calculation model of joint surfaces by considering the variation of critical deformation in contact process.

This paper aims to propose a normal and tangential contact stiffness model to investigate the contact characteristics between rough surfaces of machined joints based on fractal geometry and contact mechanics theory considering surface asperities interaction.

The fractal geometry theory describes surface topography and Hertz contact theory derives the asperities elastic, elastic-plastic and plastic contact deformation. The joint normal and tangential contact stiffness are obtained. The experiment method for normal and tangential contact stiffness are introduced.

The relationship between dimensionless normal contact load and dimensionless normal and tangential contact stiffness are analyzed in different plasticity index. The results show that they are nonlinear relationships. The normal and tangential contact stiffness are obtained based on theoretical and experimental methods for milling and grinding machined specimens. The results indicate that the present model for the normal and tangential contact stiffness are consistent with experimental data, respectively.

The normal and tangential contact stiffness models are constructed by using the fractal geometry and the contact mechanics theory considering surface asperities interaction, which includes fully elastic, elastic-plastic and fully plastic contacts deformation. The present method can generate a more reliable calculation result as compared with the contact model no-considering asperities interaction.

To review, analyze and present the effects of the contact‐fluid interfacial shear strength and contact‐fluid interfacial slippage and the critical importance of these effects in elastohydrodynamic lubrication (EHL).

The experimental and theoretical research results of the contact‐fluid interfacial shear strength and its caused contact‐fluid interfacial slippage in hydrodynamic lubrication and especially in EHL obtained in the past decades and progressed in recent years by the present author and by others are reviewed. Analysis and presentation are made on both the contact‐fluid interfacial shear strength versus fluid pressure curve for a given bulk fluid temperature in an isothermal EHL and the influence of the bulk fluid temperature on this curve.

It is very clearly and well understood from the present paper that the value of the contact‐fluid interfacial shear strength in the inlet zone in an EHL contact, i.e. at low EHL fluid film pressures is usually low and usually has rather a weak dependence on the EHL fluid film pressure. This proves the correctness of the EHL theories previously developed by the author based on the assumption of this low value and dependence on the EHL fluid film pressure of the contact‐fluid interfacial shear strength. It is also very clearly understood that the bulk fluid temperature usually has a strong influence on the value of the contact‐fluid interfacial shear strength in EHL and the increase of this temperature usually significantly reduces the value of the contact‐fluid interfacial shear strength in EHL.

A very useful material for the engineers who are engaged in the design of EHL on gears, cams and roller bearings, and for the tribology scientists who thrust efforts in studying EHL and mixed EHL both by theoretical modeling and by experiments.

A new and generalized mode of mixed EHL is originally proposed by incorporating the finding of a more realistic mode of the contact regimes in a practical mixed EHL based on the contact‐fluid interfacial shear strength and contact‐fluid interfacial slippage effects. This mode of mixed EHL should become the direction of the theoretical research of mixed EHL in the future.

The transgender community faces prejudice and stigma and is one of the most ostracised groups in society. One of the ways to reduce prejudice is through intergroup contact. This may be achieved through direct or indirect contact. The purpose of this paper is to compare the impact of direct and indirect contact on reducing transphobia.

Direct contact was achieved through a transgender speaker panel and indirect contact involved a video presentation. In total, 159 students enroled in undergraduate courses at a prominent university in India were enlisted for this study. Perceptions regarding transgenders were measured using the genderism and transphobia scale. Perceptions were measured at three different time points – before the contact, immediately after the contact and one month post contact.

Results indicate that both direct and indirect contact cause a significant immediate decrease in transphobia at the post intervention stage. However, only direct contact caused significant reduction at the follow-up stage (one month after the intervention). Direct contact also effected a greater reduction in transphobia than indirect contact.

This study extends previous research that shows that speaker panels involving sexual minority speakers can result in reducing stigma (e.g. Croteau and Kusek, 1992). The present study shows that such speaker panels can also be useful for reducing stigma against transgender individuals. Another important outcome of this study is the relative effectiveness of direct contact in reducing transphobia compared to indirect contact. Direct contact resulted in greater reduction in transphobia both at the post-test and follow-up stages compared to indirect contact.

The results of this study may benefit HR practitioners and policy makers in designing workplace initiatives and policies in creating an inclusive workplace. This study shows that meaningful interaction with transgenders would be a key step in reducing stigmatisation. Since direct contact is rarely expensive or time consuming, it can be a valuable tool to improve the integration of transgender individuals within society. Therefore, students and employees may be encouraged to interact with transgender individuals through panel discussions and workshops. Indirect contact may be used as a preliminary intervention in certain cases where direct contact may be difficult to organise.

The stigma faced by transgender individuals has a significant negative impact on their quality of life (Grant et al., 2014; Reisner and Juntunen, 2015). It is, therefore, necessary to recognise and reduce prejudice against transgenders at both the college and school levels as well as in work organisations. Educators and managers have a significant role to play in this societal change. This study shows that stigma reduction can be achieved in a fairly simple way through contact theory.

This study is one of the first to investigate Indian students’ perceptions of transgenders. It improves on earlier studies using similar interventions in two main ways. First, this study includes a follow-up assessment, which was not performed in most studies. Second, random assignment of participants to one of two conditions improves the reliability of the findings.

The purpose of this paper is to introduce the concept of constructive intercultural contact. This concept refers to intercultural contact in which majority as well as minority participants are intercultural effective, i.e. can perceive themselves as comfortable and successful.

This study is based on exploration and review of intergroup, contact, acculturation and organization literature.

Five input elements of constructive intercultural contact are distinguished: responsibility, deliberate choice to postpone judgment, acknowledging the relative relevance of cultural differences, perspective taking and respect. What participants have to do to make constructive intercultural contact in organizations not only possible between colleagues, but also in hierarchical relationships is elaborated by reflection on the interrelation between majority/minority and manager/employee positions in constructive intercultural contact.

This paper contributes to diversity management literature by introducing a new concept which, focusing on the interaction level, explains how participants can make intercultural contact into a comfortable and successful experience for both. Other contributions are the differentiation between majority and minority actors and the elaboration of the complexity of intercultural employee/manager contacts.

This paper aims to propose a semi-analytical model to investigate the elastic-plastic contact between fractal rough surfaces. Parametric studies have been performed to analyze the dependencies between the contact properties and the scale-independent fractal parameters.

A modified two-variable Weierstrass-Mandelbrot function has been used to build the geometrical model of rough surfaces. The computation program was developed using software MATLAB R2015a. The results have been qualitatively validated by the existing theoretical and experimental results in the literature.

In most cases, a nonlinear relation between the load and the displacement of the rigid plane is found. Only under the condition of larger loads, an approximate linear relation can be seen for great D and small G values. (D: fractal dimension and G: fractal roughness).

The contact model of the cylindrical joints (conformal contact) with radial clearance is constructed by using the fractal theory and the Kogut-Etsion elastic-plastic contact model, which includes purely elastic, elastic-plastic and fully plastic contacts. The present method can generate a more reliable calculation result as compared with the Hertz contact model and a higher calculation efficiency as compared with the finite element method for the conformal contact problem.

The purpose of this paper is to describe a method permitting the creation of a realistic model of spherical roller bearing with the aim of determining contact stress and fatigue life based on dynamic loading conditions. The paper also aims to recognize the effect of tolerance values on contact stress and fatigue life. Motion and load transmission in spherical roller bearing occurs within the assembly by elliptical curved contacting surfaces. The stress produced by the transmitted load would be very high because of least contacting area between these surfaces.

The paper describes a methodology to determine contact stress using analytically as well as finite element method for spherical roller bearing. The comparison for the both each approach for contact stress at different loading condition is carried out. Prediction of fatigue life based on dynamic loading conditions for bearing is also determined using finite element model. The effect on induced contact stress and fatigue life by varying tolerances on inner race dimensions have been found out.

The paper suggests that the maximum stress produces at the start or end of the contacting arc under static loading condition in spherical roller bearing. The analytical and finite element approach is in good agreement. The fatigue life prediction is useful for selecting loading conditions for various applications of double row spherical roller bearing. Tolerance level at inner ring raceway radius is kept high because of manufacturing constrain of complex curvature geometric shape.

The present approach does not consider dynamic loading conditions for contact stress analysis. Therefore, researchers are encouraged to analyze the effect of wear, lubrication and other tribological aspects on bearing life.

The paper includes determination of contact stress and prediction of fatigue life for spherical roller bearing using analytical as well as finite element approach. The tolerance values at inner race are identified as per manufacturing constraint based on contact stress and fatigue life.

This research aims to better understand the issues of why individualised communications should be incorporated into customised customer contact service and how customer contact management should be implemented.

The qualitative methodology of case research was used. In total nine Australian service industry case studies, involving 34 in‐depth interviews, were undertaken.

The analysis revealed three themes: optimisation of market factors, the process of implementation, and requirements for smooth customer contact management implementation. These findings showed minor implementation problems with service and organisational requirements driving customer contact management implementation overall. In addition, factors to assist with smooth customer contact management implementation are identified.

Limitations, which could be addressed by future research, include application to other industries, expansion to other countries, the consumer perspective and the need for statistical generalisation.

Key practical implications include the identification of the need for firms to consider customer contact management as an avenue for differentiation and competitive advantage as well as providing guidelines for the successful implementation of customer contact management.

This research builds theory about customer contact management for the first time.

This chapter aims at providing insight into how social mixing plays out in the Transvaal neighborhood in Amsterdam — a neighborhood which has gone through various rounds of urban renewal — in the context of nationwide polarization between native-Dutch and Moroccan-Dutch.

This chapter is based on research with a neighborhood focus — daily interactions, urban renewal, and use of public space — which took place during 2007–2010. Methods used include participant observation, semistructured interviews, and focus groups.

The physical renewal implies renovating and pulling down social housing, and building new social or owner-occupier housing. This study provides insight into how residents of different ethnic and income backgrounds live together in the neighborhood, also taking into account the impact of social polarization at the national level.

By knowing how people with different ethnic and class backgrounds live together in Transvaal neighborhood, it contributes to the formulation of evidence-based policies for the improvement of social cohesion, livability, safety of the neighborhood, and social capital of local residents.

This study looks at social mix in the context of national-level social polarization between native-Dutch and Moroccan-Dutch. This creates a new viewpoint seen against how the general literature on renewal and social mixing tends to do two things: firstly it usually explicitly or implicitly is also a tenure mix strategy, and secondly the policy focus of the social mix is usually around class issues, that is, the mixing of poor social housing tenants with richer owners.