Velocity Measurements
Recently Published Documents





2022 ◽  
Vol 238 ◽  
pp. 111867
Peng Zhang ◽  
István Gyula Zsély ◽  
Máté Papp ◽  
Tibor Nagy ◽  
Tamás Turányi

2022 ◽  
Vol 163 (2) ◽  
pp. 63
Taro Matsuo ◽  
Thomas P. Greene ◽  
Mahdi Qezlou ◽  
Simeon Bird ◽  
Kiyotomo Ichiki ◽  

Abstract The direct measurement of the universe’s expansion history and the search for terrestrial planets in habitable zones around solar-type stars require extremely high-precision radial-velocity measures over a decade. This study proposes an approach for enabling high-precision radial-velocity measurements from space. The concept presents a combination of a high-dispersion densified pupil spectrograph and a novel line-of-sight monitor for telescopes. The precision of the radial-velocity measurements is determined by combining the spectrophotometric accuracy and the quality of the absorption lines in the recorded spectrum. Therefore, a highly dispersive densified pupil spectrograph proposed to perform stable spectroscopy can be utilized for high-precision radial-velocity measures. A concept involving the telescope’s line-of-sight monitor is developed to minimize the change of the telescope’s line of sight over a decade. This monitor allows the precise measurement of long-term telescope drift without any significant impact on the Airy disk when the densified pupil spectra are recorded. We analytically derive the uncertainty of the radial-velocity measurements, which is caused by the residual offset of the lines of sight at two epochs. We find that the error could be reduced down to approximately 1 cm s−1, and the precision will be limited by another factor (e.g., wavelength calibration uncertainty). A combination of the high-precision spectrophotometry and the high spectral resolving power could open a new path toward the characterization of nearby non-transiting habitable planet candidates orbiting late-type stars. We present two simple and compact highly dispersed densified pupil spectrograph designs for cosmology and exoplanet sciences.

2022 ◽  
Stefan Möstl ◽  
Fabian Hoffmann ◽  
Jan-Niklas Hönemann ◽  
Jose Ramon Alvero-Cruz ◽  
Jörn Rittweger ◽  

Aim. Pulse wave velocity independently predicts cardiovascular risk. Easy to use single cuff oscillometric methods are utilized in clinical practice to estimate pulse wave velocity. We applied the approach in master athletes to assess possible beneficial effects of lifelong exercise on vascular health. Furthermore, we compared single cuff measurements with a two-cuff method in another cohort. Methods. We obtained single cuff upper arm oscillometric measurements thrice in 129 master athletes aged 35 to 86 years and estimated pulse wave velocity using the ArcSolver algorithm. We applied the same method in 24 healthy persons aged 24 to 55 years participating in a head down tilt bedrest study. In the latter group, we also obtained direct pulse wave velocity measurements using a thigh cuff.Results. Estimated pulse velocity very highly correlated with age (R2 = 0.90) in master athletes. Estimated pulse wave velocity values were located on the same regression line like values obtained in participants of the head down tilt bed rest study. The modest correlation between estimated and measured PWV (r² 0.40; p<0.05) was attenuated after adjusting for age; the mean difference between pulse wave velocity measurements was 1 m/s.Conclusion. Estimated pulse wave velocity mainly reflects the entered age rather than true vascular properties and, therefore, failed detecting beneficial effects of life long exercise.Funding. The AGBRESA-Study was funded by the German Aerospace Center (DLR), the European Space Agency (ESA, contract number 4000113871/15/NL/PG) and the National Aeronautics and Space Administration (NASA, contract number 80JSC018P0078). Fabian Hoffmann received funding by the DLR and the German Federal Ministry of Economy and Technology, BMWi (50WB1816). SM, JT and JJ were supported by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology, BMK (SPACE4ALL Project, FFG No. 866761).

2022 ◽  
Vol 163 (2) ◽  
pp. 53
Nicholas Saunders ◽  
Samuel K. Grunblatt ◽  
Daniel Huber ◽  
Karen A. Collins ◽  
Eric L. N. Jensen ◽  

Abstract While the population of confirmed exoplanets continues to grow, the sample of confirmed transiting planets around evolved stars is still limited. We present the discovery and confirmation of a hot Jupiter orbiting TOI-2184 (TIC 176956893), a massive evolved subgiant (M ⋆ = 1.53 ± 0.12 M ⊙, R ⋆ = 2.90 ± 0.14 R ⊙) in the Transiting Exoplanet Survey Satellite (TESS) Southern Continuous Viewing Zone. The planet was flagged as a false positive by the TESS Quick-Look Pipeline due to periodic systematics introducing a spurious depth difference between even and odd transits. Using a new pipeline to remove background scattered light in TESS Full Frame Image data, we combine space-based TESS photometry, ground-based photometry, and ground-based radial velocity measurements to report a planet radius of R p = 1.017 ± 0.051 R J and mass of M p = 0.65 ± 0.16 M J . For a planet so close to its star, the mass and radius of TOI-2184b are unusually well matched to those of Jupiter. We find that the radius of TOI-2184b is smaller than theoretically predicted based on its mass and incident flux, providing a valuable new constraint on the timescale of post-main-sequence planet inflation. The discovery of TOI-2184b demonstrates the feasibility of detecting planets around faint (TESS magnitude > 12) post-main-sequence stars and suggests that many more similar systems are waiting to be detected in the TESS FFIs, whose confirmation may elucidate the final stages of planetary system evolution.

2022 ◽  
Anders Hansen ◽  
John Griffin ◽  
Adam C. Moya

2022 ◽  
pp. 127404
Farhad Bahmanpouri ◽  
Silvia Barbetta ◽  
Carlo Gualtieri ◽  
Marco Ianniruberto ◽  
Naziano Filizola ◽  

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 162
Katarzyna Socha ◽  
Paweł Jamróz

Changes in the temperature of the medium significantly affect the static characteristics of hot-wire anemometry measuring wires, which causes errors in the results of flow velocity measurements. High temperatures of the medium make it necessary to additionally heat the sensor to even higher temperatures, which may lead to its damage due to wire burnout. The article proposes a solution to the problem of measuring the flow velocity in conditions of non-stationary temperatures with the use of the method of cross-correlation of signals from two-wire resistance thermometers. The main assumptions of the method and its experimental verification were presented.

Sign in / Sign up

Export Citation Format

Share Document