OPTIMIZED BOGIE SYSTEM DAMPING WITH RESPECT TO SAFETY AND COMFORT

Here the lateral damping (two dampers) is optimized and investigated with respect to safety and comfort for an eight degree of freedom model of a train bogie. The train bogie model is nonlinear due to the excitations caused by the irregularities and the wheel–track interface forces. Train running at different speeds will have different optima and optimal damping parameters with respect toboth comfort and safety. The aim is to optimize the dynamic behavior for a wide range of forward service speeds up to 300 km/h. A multiobjective optimization routine is used and the results are presented in terms of Pareto fronts. To optimize the behavior semi–active functional componentsare required. A scheme to control semi–active lateral damping components with respect to forward speed is suggested. This can significantly improve the dynamic behavior with simultaneously respect to safety and comfort. Finally, we investigate the use of two lateral damping components with the possibility to change behavior at a certain switch time. At least for some service speedsthese semi-active damping components are find to be able to improve the dynamic behavior. The understanding of the influence of the design parameters is valuable in further improving the general performance of a high speed train with respect to safety and comfort

Tracks for change, flexibility, interdisciplinarity and creativity in engineering education

This paper describes the early stages of the developments of Tracks, an initiative to create,implement and evaluate a new educational model where the structure of the education isdeveloped to give students the opportunity to create multi- and interdisciplinary competencies,meet their expectations and need for a more individualized study plan and shorten the leadtimes for changing the education to embrace new technologies. The new education model isbased on the creation of tracks with different themes lying between existing programs notbelonging to a specific department or school. The idea is to create individual and flexible studyopportunities by introducing Track-courses within the themes. These courses address specificchallenges that may be broad societal and profound research-driven. Tracks also include largeinvestments in Chalmers learning environment. The paper focuses on Tracks as a largechange initiative, strategies to manage the complexity of this change as well as developmentphilosophy and working methods in the early phases of the initiative. Change at universitieshas been discussed previously, but this is a unique opportunity to study how large change maybe managed over time, including both the content of the education and the learningenvironments. Through action research, where interventions may be done to influence theinitiative, it is possible to develop practical contributions for other universities in need of similardevelopment. The research has been conducted over approximately a year and includes datafrom interviews and action research, where the authors are the main people working with thisinitiative. The close contact with the data gives a unique understanding of how differentactivities within the initiative influence the outcome. Thus, this paper will contribute to theunderstanding of how large institutional change initiatives are facilitated by a flexible and agileapproach contrasting the traditional and somewhat slower university culture

Vibration dynamics of high speed train with Pareto optimized damping of bogie suspension to enhance safety and comfort

A methodology to find the optimized, with respect to safety and comfort, lateral damping of both the primary and secondary suspensions of a bogie system for a high speed train (HST) has been developed, implemented and evaluated. The vibration dynamics of three-car HST with safety-comfort Pareto optimized lateral damping of bogie system is analyzed. The sensitivity of vibration dynamics of the HST having Pareto optimized lateral damping and traveling with 250 km/h is studied for different vehicle speeds, wheels and rails wornness, train service loads and frictions between wheels and rails. Numerical results show that Pareto optimized lateral damping of bogie system can significantly improve passenger comfort while maintain safety and reliability of HST performance

Vibration dynamics of high speed train with Pareto optimized damping of bogie suspension to enhance safety and comfort

A methodology to find the optimized, with respect to safety and comfort, lateral damping of both the primary and secondary suspensions of a bogie system for a high speed train (HST) has been developed, implemented and evaluated. The vibration dynamics of three-car HST with safety-comfort Pareto optimized lateral damping of bogie system is analyzed. The sensitivity of vibration dynamics of the HST having Pareto optimized lateral damping and traveling with 250 km/h is studied for different vehicle speeds, wheels and rails wornness, train service loads and frictions between wheels and rails. Numerical results show that Pareto optimized lateral damping of bogie system can significantly improve passenger comfort while maintain safety and reliability of HST performance

OPTIMIZED BOGIE SYSTEM DAMPING WITH RESPECT TO SAFETY AND COMFORT

Here the lateral damping (two dampers) is optimized and investigated with respect to safety and comfort for an eight degree of freedom model of a train bogie. The train bogie model is nonlinear due to the excitations caused by the irregularities and the wheel–track interface forces. Train running at different speeds will have different optima and optimal damping parameters with respect toboth comfort and safety. The aim is to optimize the dynamic behavior for a wide range of forward service speeds up to 300 km/h. A multiobjective optimization routine is used and the results are presented in terms of Pareto fronts. To optimize the behavior semi–active functional componentsare required. A scheme to control semi–active lateral damping components with respect to forward speed is suggested. This can significantly improve the dynamic behavior with simultaneously respect to safety and comfort. Finally, we investigate the use of two lateral damping components with the possibility to change behavior at a certain switch time. At least for some service speedsthese semi-active damping components are find to be able to improve the dynamic behavior. The understanding of the influence of the design parameters is valuable in further improving the general performance of a high speed train with respect to safety and comfort

Chalmers University of Technology: Overcoming Resistance and Inertia in Education through the Dynamics of a Matrix Organization Including Student Co-Creation

In this contribution we describe and reflect on the organization of Chalmers University of Technology and how it benefits education development and innovation. Chalmer’s matrix organization with a buyer-supplier management model for education has proven to be a driving force for change and quality enhancement and promotes the agility necessary for implementing educational reforms in response to both internal and external impulses. We exemplify this by describing and analyzing development projects in curriculum design, education for sustainable development, entrepreneurship, and a new transformative model for flexible education

Learning Mechatronics Using Digital Live Labs

Practical skills training in laboratories are important elements and learning outcomes in engineering education, where leaners, through exploration, experimentation and reflection engage in inquiry-based learning that stimulate the acquisition of deep conceptual domain knowledge and inquiry skills. Traditional lab environments are very costly to maintain, partly unsafe and often require proximity of instructors and/or students that is in conflict with the Covid-19-driven need for physical/social distancing. In this paper, we describe and evaluate a course in logic control that used online labs both in pure online and in hybrid format. Students reported very high satisfaction with all three formats and achieved similar learning performances. However, qualitative analyses indicate that student learning is deeper and more authentic in the on-campus and hybrid formats compared to the pure online format. Teacher reflections show an overall positive impression of online labs. In conclusion, we recommend the hybrid format as it combines the benefits of online and physical labs, i.e., the flexibility of online laboratory work and realism of hands-on physical laboratory work

Learning Mechatronics Using Digital Live Labs

Practical skills training in laboratories are important elements and learning outcomes in engineering education, where leaners, through exploration, experimentation and reflection engage in inquiry-based learning that stimulate the acquisition of deep conceptual domain knowledge and inquiry skills. Traditional lab environments are very costly to maintain, partly unsafe and often require proximity of instructors and/or students that is in conflict with the Covid-19-driven need for physical/social distancing. In this paper, we describe and evaluate a course in logic control that used online labs both in pure online and in hybrid format. Students reported very high satisfaction with all three formats and achieved similar learning performances. However, qualitative analyses indicate that student learning is deeper and more authentic in the on-campus and hybrid formats compared to the pure online format. Teacher reflections show an overall positive impression of online labs. In conclusion, we recommend the hybrid format as it combines the benefits of online and physical labs, i.e., the flexibility of online laboratory work and realism of hands-on physical laboratory work

Creep and Fracture in Concrete: A Fractional Order Rate Approach

The paper analyses the interaction between strain-softening and time-dependent behaviour in the case of quasi-static fracture of concrete. A viscous element based on a fractional order rate law is coupled with a micromecanical model for the fracture process zone. This approach makes it possible to include a whole range of dissipative mechanisms in a single rheological element. Creep fracture in mode I conditions is analysed through the finite element method, the cohesive (or fictitious) crack model and a new space and time integration scheme. The comparison with creep tests executed on three-point bending conditions shows a good agreement

The Heterogeneity of Asthma Phenotypes in Children and Young Adults

Objective. Genetic heterogeneity and risk factor distribution was analyzed in two previously proposed asthma phenotypes. Method. A sample of 412 subjects was investigated at 7-8, 12-13, and 21-22 years of age with questionnaires, skin prick tests, and genetic analysis of IL-4 receptor (IL4R) single-nucleotide polymorphisms. The sample was subdivided in one group with no asthma, and two groups with asthma separated by age of onset of symptoms, namely, early onset asthma (EOA) and late onset asthma (LOA). Risk factors and IL4R markers were analyzed in respect to asthma phenotypes. Results. EOA and LOA groups were both associated with atopy and a maternal history of asthma. Female gender was more common in LOA, whereas childhood eczema, frequent colds in infancy, and a paternal history of asthma were more common in EOA. The AA genotype of rs2057768 and the GG genotype of rs1805010 were more common in LOA, whereas the GG genotype of rs2107356 was less common in EOA. Conclusion. Our data suggest that early and late onset asthma may be of different endotypes and genotypes