Search results
1 – 10 of 262M. Kaltenbacher, M. Rausch, H. Landes and R. Lerch
A new method for the numerical computation of the dynamic behaviour of electro‐dynamic loudspeakers is presented. The numerical scheme, based on the finite element method (FEM)…
Abstract
A new method for the numerical computation of the dynamic behaviour of electro‐dynamic loudspeakers is presented. The numerical scheme, based on the finite element method (FEM), allows the simulation of coupled magnetic, mechanical and acoustic fields. The obtained simulation results are in good agreement with measured data.
Details
Keywords
M. Rausch, M. Kaltenbacher, H. Landes and R. Lerch
A recently developed calculation scheme for the numerical computation of the load‐controlled acoustic noise of power transformers is presented. This modeling scheme allows the…
Abstract
A recently developed calculation scheme for the numerical computation of the load‐controlled acoustic noise of power transformers is presented. This modeling scheme allows the precise and efficient computation of the coupled electromagnetic, mechanical and acoustic fields. The equations are solved using the finite element method (FEM) as well as the boundary element method (BEM), resulting in a separation of the acoustic‐magnetomechanical calculation of the winding vibrations resp. the acoustic‐mechanical computation of the tank vibrations (using FEM) and the calculation of the acoustic free‐field radiation (using BEM). The validity of the computer simulations has been verified by means of appropriate measurements. Simulated and measured values for winding and tank surface vibrations as well as the sound power level of the loaded transformer are found to be in good agreement.
Details
Keywords
M. Ertl, M. Kaltenbacher, R. Mock and R. Lerch
This paper presents a 2D nonlinear magnetomechanical analysis of an electromagnetic actuator based on finite elements. An impact mechanical problem with its inherent convergence…
Abstract
This paper presents a 2D nonlinear magnetomechanical analysis of an electromagnetic actuator based on finite elements. An impact mechanical problem with its inherent convergence problems has to be solved inside the magnetic field region. Beside material and geometric nonlinearities also dynamic effects like eddy currents are considered.
Details
Keywords
Michael Ertl and Manfred Kaltenbacher
The fast and flexible development of fast switching electromagnetic valves as used in modern gasoline engine demands the availability of efficient and accurate simulation tools…
Abstract
Purpose
The fast and flexible development of fast switching electromagnetic valves as used in modern gasoline engine demands the availability of efficient and accurate simulation tools. The purpose of this paper is to provide an enhanced computational scheme of these actuators including all relevant physical effects of magneto‐mechanical systems and including contact mechanics.
Design/methodology/approach
The finite element (FE) method is applied to efficiently solve the arising coupled system of partial differential equations describing magneto‐mechanical systems. The algorithm for contact mechanics is based on the cross‐constraint method using an energy‐ and momentum‐conserving time‐discretisation scheme. Although solving separately for the electromagnetic and mechanical system, a strong coupling is ensured within each time step by an iterative process with stopping criterion.
Findings
The numerical simulations of the full switching cycle of an electromagnetic direct injection valve, including the bouncing during the closing state, are just feasible with an enhanced and robust mechanical contact algorithm. Furthermore, the solution of the nonlinear electromagnetic and mechanical equations needs a Newton scheme with a line search scheme for the relaxation of the step size.
Originality/value
The paper provides a numerical simulation scheme based on the FE method, which includes all relevant physical effects in magneto‐mechanical systems, and which is robust even for long‐term contact periods with multitude re‐opening phases.
Details
Keywords
This chapter reviews the historical and political context of immigration to Norway, patterns of ethnic inequality in the labour market, as well as how ethnic discrimination has…
Abstract
This chapter reviews the historical and political context of immigration to Norway, patterns of ethnic inequality in the labour market, as well as how ethnic discrimination has been legislated, publically debated and studied in the Norwegian context. Drawing on the findings of a multimethod study of discrimination in the Norwegian labour market, combining a field experiment with employer-interviews, the chapter furthermore clarifies the extent of discrimination in ethnic minority applicants’ access to the labour market and discusses what mechanisms influence the level of ethnic discrimination ‘at work’. The field experiment reveals that young Norwegians of Pakistani heritage – the by far largest group among immigrant descendants in the country – face substantial discrimination when applying for work. However, it also demonstrates striking differences in the scope of discrimination between the public and the private sector, as well as across occupational contexts, indicating that discrimination should not be seen as mere reflections of individual bias, ethnic preferences or statistical uncertainty, but rather that such individual-level dispositions are mediated through factors at the organizational level. This conclusion has important implications for our theoretical understanding of why discrimination occurs, as well as for the further development of anti-discrimination measures.
Details
Keywords
R. Jerome and N. Ganesan
A thermal analogy method for the static and dynamic analysis of an electrostrictive beam by incorporating the nonlinear characteristics of the electrostrictive materials is…
Abstract
A thermal analogy method for the static and dynamic analysis of an electrostrictive beam by incorporating the nonlinear characteristics of the electrostrictive materials is described in this paper. The analogy between thermo elastic finite element formulation and the electrostrictive material finite element formulation developed in this paper was explored. Based on this analogy, the voltage actuation of the electrostrictive beam can be simulated accurately using the conventional elastic finite element model with the thermal actuation. The finite element model includes the quadratic dependence of strain with electric field, valid at constant temperature and mechanical prestress, and excludes hysteresis.
Details
Keywords
Mark Mortensen and Pamela J. Hinds
Though geographically distributed teams are rapidly increasing in prevalence, empirical research examining the effect of distance on group process has not kept pace. In a study of…
Abstract
Though geographically distributed teams are rapidly increasing in prevalence, empirical research examining the effect of distance on group process has not kept pace. In a study of 24 product development teams located within five companies, we attempt to bridge the gap between research and practice by comparing the amount of affective and task conflict reported in collocated versus geographically distributed teams. We further examine how conflict is impacted by shared team identity, cultural heterogeneity, and reliance on technology for communication. As hypothesized, shared team identity was associated with less task conflict within distributed, but not collocated teams. Similar effects were found for affective conflict, suggesting that a shared identity may help distributed teams to better manage conflict. Our results also suggest more task conflict on teams that rely heavily on technology to mediate their communications. In examining performance, we found some support for our hypothesis that conflict would be more detrimental for distributed than collocated teams.
Kristen Gillespie-Lynch, Patrick Dwyer, Christopher Constantino, Steven K. Kapp, Emily Hotez, Ariana Riccio, Danielle DeNigris, Bella Kofner and Eric Endlich
Purpose: We critically examine the idea of neurodiversity, or the uniqueness of all brains, as the foundation for the neurodiversity movement, which began as an autism rights…
Abstract
Purpose: We critically examine the idea of neurodiversity, or the uniqueness of all brains, as the foundation for the neurodiversity movement, which began as an autism rights movement. We explore the neurodiversity movement's potential to support cross-disability alliances that can transform cultures.
Methods/Approach: A neurodiverse team reviewed literature about the history of the neurodiversity movement and associated participatory research methodologies and drew from our experiences guiding programs led, to varying degrees, by neurodivergent people. We highlight two programs for autistic university students, one started by and for autistics and one developed in collaboration with autistic and nonautistic students. These programs are contrasted with a national self-help group started by and for stutterers that is inclusive of “neurotypicals.”
Findings: Neurodiversity-aligned practices have emerged in diverse communities. Similar benefits and challenges of alliance building within versus across neurotypes were apparent in communities that had not been in close contact. Neurodiversity provides a framework that people with diverse conditions can use to identify and work together to challenge shared forms of oppression. However, people interpret the neurodiversity movement in diverse ways. By honing in on core aspects of the neurodiversity paradigm, we can foster alliances across diverse perspectives.
Implications/ Values: Becoming aware of power imbalances and working to rectify them is essential for building effective alliances across neurotypes. Sufficient space and time are needed to create healthy alliances. Participatory approaches, and approaches solely led by neurodivergent people, can begin to address concerns about power and representation within the neurodiversity movement while shifting public understanding.
Details
Keywords
Arwen H. DeCostanza, Katherine R. Gamble, Armando X. Estrada and Kara L. Orvis
Unobtrusive measurement methodologies are critical to implementing intelligent tutoring systems (ITS) for teams. Such methodologies allow for continuous measurement of team states…
Abstract
Unobtrusive measurement methodologies are critical to implementing intelligent tutoring systems (ITS) for teams. Such methodologies allow for continuous measurement of team states and processes while avoiding disruption of mission or training performance, and do not rely on post hoc feedback (including for the aggregation of data into measures or to develop insights from these real-time metrics). This chapter summarizes advances in unobtrusive measurement developed within Army research programs to illustrate the variety and potential that unobtrusive measurement approaches can provide for building ITS for teams. Challenges regarding the real-time aggregation of data and applications to current and future ITS for teams are also discussed.
Details
Keywords
Rajalakshmi Subramaniam, Senthilkumar Nakkeeran and Sanjay Mohapatra