scholarly journals Empirically Bounding of Space Booms with Tape Spring Hinges

2013 ◽  
Vol 20 (3) ◽  
pp. 503-517 ◽  
Author(s):  
A.L. Jennings ◽  
J. Black ◽  
C. Allen
Keyword(s):  
Large Amplitude ◽  
Large Scale ◽  
Free Fall ◽  
Free Condition ◽  
Elliptical Motion ◽  
Scale Behavior

Self-deploying structures seek to provide a compact launch package for large, lightweight satellite booms. One self-deploying method is a foldable tape spring. This paper examines the large scale behavior of a boom attached by a tape spring hinge during mock deployments. A boom attached by tape spring to a rigid stand was released and the boom bounced up to 60° before coming to rest (as opposed to snap-through behavior). These large amplitude bounces can cause the boom to collide with sensors, other booms or arrays causing damage or preventing full deployment. Results show the first bounce of deployment is nearly bounded by a four parameter ellipse. The ellipses of similar folds are similar also, suggesting that a model can be developed. Free-fall tests simulating the free-free condition found in microgravity also show similar elliptical motion. Envelopes that bound the extents of the boom motion allow for collisions to be prevented by adjustment of the design.

Ambivalence and Adherence to Measures to Reduce the Spread of COVID-19

2021 ◽  
Author(s):  
Iris K. Schneider ◽  
Angela Rachael Dorrough ◽  
Celine Frank
Keyword(s):  
Behavioral Change ◽  
Large Scale ◽  
Direct Costs ◽  
Pharmaceutical Treatment ◽  
Mixed Emotions ◽  
German Sample ◽  
Mixed Feelings ◽  
Spread Of Infection ◽  
Scale Behavior

The COVID-19 pandemic poses one of the largest behavioral change challenges in the last decades. Because currently, there is no widely available pharmaceutical treatment available to contain the spread of infection, governments worldwide rely – at least to some extent – on behavioral recommendations aimed at reducing spread. The success of this strategy is dependent on the number of people that follow the recommendations. Most recommendations need people to change their behavior or adopt a new behavior. We propose that such behavioral change, with direct costs and delayed benefits, is a source of conflict and mixed feelings. This ambivalence negatively affects adherence to such recommendations. We present three studies that support our hypotheses: the more ambivalent people are about the recommendations, the less they follow them. We also examined the effect of the mixed emotions of hope and worry on adherence and find that it positively relates to adherence. Our findings replicated both in a U.S. sample as well as a representative German sample. Our work is the first to investigate the role of ambivalence in large-scale behavior change and highlight the importance of understanding the conflict that comes with changing behavior. We discuss implications for policy and communication.

Effect of gravity curvature on large-scale atomic gravimeters

2021 ◽  
Author(s):  
Dorothee Tell ◽  
Étienne Wodey ◽  
Christian Meiners ◽  
Klaus H. Zipfel ◽  
Manuel Schilling ◽  
...  
Keyword(s):  
Large Scale ◽  
Vibration Isolation ◽  
High Sensitivity ◽  
Free Fall ◽  
Theory Approach ◽  
Gravity Gradients ◽  
Lower Saxony ◽  
German Research Foundation ◽  
Absolute Gravimetry ◽  
Funding Program

<p>In terrestrial geodesy, absolute gravimetry is a tool to observe geophysical processes over extended timescales. This requires measurement devices of high sensitivity and stability. Atom interferometers connect the free fall motion of atomic ensembles to absolute frequency measurements and thus feature very high long-term stability. By extending their vertical baseline to several meters, we introduce Very Long Baseline Interferometry (VLBAI) as a gravity reference of higher-order accuracy.</p><p>By using state-of-the-art vibration isolation, sensor fusion and well controlled atomic sources and environments on a 10 m baseline, we aim for an intrinsic sensitivity σ<sub>g</sub> ≤ 5 nm/s² in a first scenario for our Hannover VLBAI facility. At this level, the effects of gravity gradients and curvature along the free fall region need to be taken into account. We present gravity measurements along the baseline, in agreement with simulations using an advanced model of the building and surroundings [1]. Using this knowledge, we perform a perturbation theory approach to calculate the resulting contribution to the atomic gravimeter uncertainty, as well as the effective instrumental height of the device depending on the interferometry scheme [2]. Based on these results, we will be able to compare gravity values with nearby absolute gravimeters and as a first step verify the performance of the VLBAI gravimeter at a level comparable to classical devices.</p><p>The Hannover VLBAI facility is a major research equipment funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). This work was supported by the DFG Collaborative Research Center 1464 “TerraQ” (Project A02) and is supported by the CRC 1227 “DQ-mat” (Project B07), Germany’s Excellence Strategy EXC-2123 “QuantumFrontiers”, and the computing cluster of the Leibniz University Hannover under patronage of the Lower Saxony Ministry of Science and Culture (MWK) and the DFG. We acknowledge support from “Niedersächsisches Vorab” through the “Quantum- and Nano-Metrology (QUANOMET)” initiative (Project QT3), and for initial funding of research in the DLR-SI institute, as well as funding from the German Federal Ministry of Education and Research (BMBF) through the funding program Photonics Research Germany.</p><p>[1] Schilling et al. “Gravity field modelling for the Hannover 10 m atom interferometer”.  Journal of Geodesy 94, 122 (2020)</p><p>[2] Ufrecht, Giese,  “Perturbative operator approach to high-precision light-pulse atom interferometry”. Physical Review A 101, 053615 (2020).</p>

A vortex interaction mechanism for generating energy and enstrophy fluctuations in high-symmetric turbulence

2019 ◽  
Vol 874 ◽  
pp. 639-676 ◽  
Author(s):  
Tatsuya Yasuda ◽  
Genta Kawahara ◽  
Lennaert van Veen ◽  
Shigeo Kida
Keyword(s):  
Periodic Motion ◽  
Large Amplitude ◽  
Large Scale ◽  
Interaction Mechanism ◽  
Wall Turbulence ◽  
Cyclic Process ◽  
High Symmetry ◽  
Dynamical Interaction ◽  
Decaying Turbulence ◽  
Axial Waves

Turbulent vortex dynamics is investigated in triply periodic turbulent flow with Kida’s high symmetry (Kida, J. Phys. Soc. Japan, vol. 54, 1985, pp. 2132–2136) by means of unstable periodic motion representing both the statistical and dynamical properties of turbulence (van Veen et al., Fluid Dyn. Res., vol. 38, 2006, pp. 19–46). In the periodic motion, the large-scale columnar vortices, the smaller-scale vortices and the large-amplitude axial waves on the large-scale columnar vortices are detected. In terms of mutual dynamical interaction between the large-scale columnar vortices and smaller-scale vortices, we demonstrate a cyclic process of excitation of the axial waves, which leads to large-amplitude fluctuations of the total kinetic energy and enstrophy. This cyclic process is characterised by three distinct phases and is therefore reminiscent of the regeneration cycle of near-wall turbulence structures (Hamilton et al., J. Fluid Mech., vol. 287, 1995, pp. 317–348). Notably, such oscillatory behaviour is observed even in freely decaying turbulence as a consequence of the instantaneous energy transfer from smaller to larger scales.

Genetic parameters for large-scale behavior traits and type traits in Charolais beef cows1

2015 ◽  
Vol 93 (9) ◽  
pp. 4277-4284 ◽  
Author(s):  
A. Vallée ◽  
I. Breider ◽  
J. A. M. van Arendonk ◽  
H. Bovenhuis
Keyword(s):  
Large Scale ◽  
Genetic Parameters ◽  
Type Traits ◽  
Scale Behavior

Effect of Pressure on the Gas Atomizer to Fabricate Stainless Steel Metal Powder

2020 ◽  
Vol 833 ◽  
pp. 54-58 ◽  
Author(s):  
Sugeng Supriadi ◽  
Tsaome Indah Susimah ◽  
Muhammad Haekal Sena Akbar ◽  
Bambang Suharno ◽  
Ario Sunar Baskoro ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Metal Powder ◽  
Large Scale ◽  
Spherical Shape ◽  
Free Fall ◽  
Gas Pressure ◽  
Raw Material ◽  
Application Process ◽  
Electric Induction ◽  
Stainless Steel 304

Metal powder is used in the Powder Metallurgy (PM) application process. Most of the metals used in the PM are stainless steel made by the gas atomization process. This study uses the free fall gas atomizer. The material was used to produce the metal powder from various forms of stainless steel 304 raw material, which is melted in an electric induction furnace. This method is very practical to be applied in the large-scale metal processing industries. While the gas pressure variation results show that metal powder with a smaller size will be produced more using high gas pressure. The free fall gas atomizer has successfully produced stainless steel 304 metal powder with the size <40 μm and have a spherical shape. The well-rounded sphericity for 8 bar pressure, 10 bar pressure, and 12 bar pressure are 61.1%, 41.7%, and 37.5% respectively. It can be concluded that 12 bar pressure produces the smallest size range of powder about <40 µm with the most quantity about 1.11%wt, followed by 10 bar pressure about 0.41%wt and 8 bar pressure about 0.07%wt.

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