Gender bias in the assessment of physical activity in population studies

Summary: Objectives: Despite their generally more health promoting behaviours, women are found to participate less in physical activity than men. This study explores possible gender bias in measurement of physical activity in population studies. Methods: Data collected by telephone (CATI) from the Berne Lifestyle Panel in 1996 is utilised. A representative sample of the population of the city of Berne comprised N=1119 cases. Gender differences are assessed for the weekly frequency of three measurements of physical activities. Results: An indicator of sport and exercise showed higher physical activity among men, while the indicator of habitual physical activity showed higher rates of daily walking and biking among women. A combined indicator of general physical activity showed no significant gender differences. Conclusions: The results provide empirical evidence on potential risk of underestimation of physical activity among women and of misclassification with respect to high or low risk behaviour pattern

The Berne-Munich Lifestyle Panel: Background and baseline results from a longitudinal health lifestyle survey

Summary: The Berne-Munich Lifestyle Panel (BMLP) studies health relevant lifestyles among some 2000 adults in Switzerland and Germany. This paper introduces the theoretical background and empirical concept of the BMLP. Sociological theory provided the guidelines for the development of an empirical model that measures structures and dynamics of health lifestyles. Health lifestyles are explained as the product of the complex interplay between health related behaviours, orientations and social resources. Residents of Berne (Switzerland) and Munich (Germany) in the age between 55 and 65 years were contacted in 12 months periods and interviewed by telephone (CATI). The questionnaire comprised some 200 questions on selected aspects of health lifestyles and health status. Interviews were conducted in two waves in Munich (1996 and 1997) and three waves in Berne (1996/97/98). The paper reports findings from baseline data analysis and explores cultural differentiations with respect to the distribution of 1. health relevant behaviours, orientations and social resources, 2. triggers of lifestyle change (life events), 3. mediating factors (Health Locus of Control, Sense of Coherence). Initial results from the search for patterns of health behaviours are also reported. The findings show considerable differences but also impressive similarities in health lifestyle elements across the two samples. There is also preliminary evidence for meaningful patterns of health behaviours in the cohort under investigation. Moreover, the findings clearly demonstrate the need for a gender specific approach in the analysis of cultural differences in health behaviours and lifestyle

Preparation of Loads and Aeroelastic Analyses of a High Altitude, Long Endurance, Solar Electric Aircraft

High altitude, long endurance aircraft can serve as platform for scientists to make observations of the earth over a long period of time. Staying airborne only by solar electric energy is, as of today, a challenge for the aircraft design and requires an extremely light weight structure at the edge of the physically possible. This paper focuses on the loads and aeroelastic aspects of such a configuration, discusses the selected strategies and presents the applied methods and tools, including the resulting models prepared for the HAPomega configuration currently under development at the DLR. Because of the structural flexibility and the slow speed of the aircraft, flight mechanical and flight control aspects interact with aeroelastics e.g. during a gust encounter, making a non-linear time domain simulation necessary. Both maneuver and gust loads are used for the structural sizing and result in a very light and slender airframe with very low eigenfrequencies

Results from Loads and Aeroelastic Analyses of a High Altitude, Long Endurance, Solar Electric Aircraft

This work presents the results of comprehensive loads and aeroelastic analyses for the design of the high altitude, long endurance, solar electric aircraft HAP. To ensure a sophisticated design, a large number of maneuver, gust, gyroscopic and landing loads cases are considered. The structural sizing results in a total primary structural mass of 38.4 kg, which is very low considering the wing span of ~28.0 m. The extreme light-weight construction (wing loading ~4.0 kg/m^2) leads to a highly flexible aircraft, making aeroelastic analyses mandatory. Results of static and dynamic aeroelastic analyses are presented, showing that the resulting design is plausible from an aeroelastic point of view

Steigerung der Robustheit von strukturellen Klebungen mittels Surface Toughening am Beispiel HAP

In the HAP (High Altitude Platform) project, the German Aerospace Center (DLR) is developing a solar-powered long-range aircraft, various payloads for Earth observation missions, the ground control station and operating concept. The mission conditions and objectives pose major challenges to the aircraft structure, especially with respect to lightweight design. From the point of manufacturing, the 27m long wing has to be manufactured in separate 1.2m long sub segments. The load carrying structure builds a round tube spar. In order to achieve the required degree of lightweight design, adhesively bonded joints are provided for the primary structure made of fiber composite material. The extremely thin structures with simultaneous highly rigid laminate orientations induce failure-triggering stress concentrations in the bonded scarf joint, which can lead to total failure of the structure during months of continuous operation. With the help of local Surface Toughening, the stress concentrations in the adhesive layer can be significantly reduced as FEA simulations show. Complementing the simulations, the concept is validated at coupon level and then transferred to the semi-automated production of the round tube spars using the winding process. Finally the spar joint is tested on element level

Surface Toughening - Ein kleiner Streifen mit großem Einfluss auf die Verbindungsfestigkeit von geklebten Primärstrukturen im Projekt HAP

In the HAP (High Altitude Platform) project, the German Aerospace Center (DLR) is developing a solar-powered long-range aircraft, various payloads for Earth observation missions, the ground control station and operating concept. The mission conditions and objectives pose major challenges to the aircraft structure, especially with respect to lightweight design. From the point of manufacturing, the 27m long wing has to be manufactured in separate 1.2m long sub segments. The load carrying structure builds a round tube spar. In order to achieve the required degree of lightweight design, adhesively bonded joints are provided for the primary structure made of fiber composite material. The extremely thin structures with simultaneous highly rigid laminate orientations induce failure-triggering stress concentrations in the bonded scarf joint, which can lead to total failure of the structure during months of continuous operation. With the help of local Surface Toughening [1], the stress concentrations in the adhesive layer can be significantly reduced as FEA simulations show. Complementing the simulations, the concept is validated at coupon level and then transferred to the semi-automated production of the round tube spars using the winding process. [1] M.J. Schollerer, et al., J. Adhes., 95:5-7, p.495-514, (2019)

Transition From Preliminary to Detailed Design of a Highly Elastic Solar Electric Aircraft

This work presents the evolution of the aeroelastic modeling of a solar electric aircraft. The dimensions (wing span of ≈27.0 m) and the extreme light-weight construction (wing loading ≈4.0 kg/m²) results in a highly flexible aircraft, making aeroelastic analyses mandatory in all stages of the aircraft design. Comparing the preliminary with the detailed design phase, the aeroelastic models are significantly improved in their level of detail. Still, the models show similar structural dynamic characteristics and a comparable loading, e.g. in terms of wing bending and torsional moments and , where the highest loads are caused by similar load cases. For the sizing, the analytic approach from the preliminary design is backed-up with numerical analyses using a detailed FE model. A comprehensive flutter analysis confirms the findings obtained from a flutter check during the preliminary design. Finally, first structural tests are prepared to validate the models

DLRK Vortrag 2021 - Klebeverbindungen der Primärstruktur innerhalb des HAP-Projektes

In the HAP (High Altitude Platform) project, the German Aerospace Center (DLR) is developing a solar-powered long-range aircraft, various payloads for Earth observation missions, the ground control station and operating concept. The mission conditions and objectives pose major challenges to the aircraft structure, especially with respect to lightweight design. This presentation intrudces the design process of bonded joints for the primary structure on the example of the wing spar, as the most critical component. The wing, with an overall span of 27m, is divided in three wing sections, with the tubular wing spar being assembled from several segments for manufacturing reasons. Considering the demanding lightweight design expectations, adhesively bonded scarfed tubular joints are selected. A manufacturing concept is developed to minimize effort for joint preparation. The dimensioning is based on global (GFEM) and detailed finite element models (DFEM) to fine-tune the design (stiffness discontinuities, surface toughness) to increase the load carrying capacity. This is flanked by physical tests for model validation and material characterization, such as adhesive characterization, to increase DFEM accuracy