Search results for "acceleration [cosmic radiation]"
showing 10 items of 34 documents
XMM-Newton observation of the supernova remnant Kes 78 (G32.8-0.1): Evidence for shock-cloud interaction
2017
The Galactic supernova remnant Kes 78 is surrounded by dense molecular clouds, whose projected position overlaps with the extended HESS gamma-ray source HESS J1852-000. The X-ray emission from the remnant has been recently revealed by Suzaku observations, which have shown indications for a hard X-ray component in the spectra, possibly associated with synchrotron radiation. We aim at describing the spatial distribution of the physical properties of the X-ray emitting plasma and at revealing the effects of the interaction of the remnant with the inhomogeneous ambient medium. We also aim at investigating the origin of the gamma-ray emission, which may be Inverse Compton radiation associated wi…
Vibration Monitoring of the Mechanical Harvesting of Citrus to Improve Fruit Detachment Efficiency
2019
The introduction of a mechanical harvesting process for oranges can contribute to enhancing farm profitability and reducing labour dependency. The objective of this work is to determine the spread of the vibration in citrus tree canopies to establish recommendations to reach high values of fruit detachment efficiency and eliminate the need for subsequent hand-harvesting processes. Field tests were carried out with a lateral tractor-drawn canopy shaker on four commercial plots of sweet oranges. Canopy vibration during the harvesting process was measured with a set of triaxial accelerometer sensors with a datalogger placed on 90 bearing branches. Monitoring of the vibration process, fruit pro…
Prediction of Vehicle Crashworthiness Parameters Using Piecewise Lumped Parameters and Finite Element Models
2018
Estimating the vehicle crashworthiness parameters experimentally is expensive and time consuming. For these reasons different modelling approaches are utilized to predict the vehicle behaviour and reduce the need for full-scale crash testing. The earlier numerical methods used for vehicle crashworthiness analysis were based on the use of lumped parameters models (LPM), a combination of masses and nonlinear springs interconnected in various configurations. Nowadays, the explicit nonlinear finite element analysis (FEA) is probably the most widely recognized modelling technique. Although informative, finite element models (FEM) of vehicle crash are expensive both in terms of man-hours put into…
Adaptive scheduling of acceleration and gyroscope for motion artifact cancelation in photoplethysmography
2022
Background and objective: Recently, various algorithms have been introduced using wrist-worn photo-plethysmography (PPG) to provide high accuracy of instantaneous heart rate (HR) estimation, including during high-intensity exercise. Most studies focus on using acceleration and/or gyroscope signals for the motion artifact (MA) reference, which attenuates or cancels out noise from the MA-corrupted PPG signals. We aim to open and pave the path to find an appropriate MA reference selection for MA cancelation in PPG.Methods: We investigated how the acceleration and gyroscope reference signals correlate with the MAs of the distorted PPG signals and derived both mathematically and experimentally a…
Effects of movement direction upon kinematic characteristics of vertical arm pointing movements in man
1998
Vertical arm pointing movements in two directions (upwards and downwards), imposing two different loads (unload and 0.5 kg) and speeds (normal and fast) have been studied in six subjects. Movements were recorded using an optoelectronic system. Data analysis concentrated upon finger-tip kinematics. Significant effects of movement direction were recorded upon velocity profiles. The acceleration time, computed relative to total movement time, was greater for downward movements than for upward movements. In contrast however, no effects of load or speed were observed. Movement time was not affected by movement direction or load, for both speeds tested. These results suggest different planning pr…
Practical strategies for stable operation of HFF-QCM in continuous air flow
2013
Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to…
Modeling the shock-cloud interaction in SN 1006: unveiling the origin of nonthermal X-ray and gamma-ray emission
2016
The supernova remnant SN 1006 is a source of high-energy particles and its southwestern limb is interacting with a dense ambient cloud, thus being a promising region for gamma-ray hadronic emission. We aim at describing the physics and the nonthermal emission associated with the shock-cloud interaction to derive the physical parameters of the cloud (poorly constrained by the data analysis), to ascertain the origin of the observed spatial variations in the spectral properties of the X-ray synchrotron emission, and to predict spectral and morphological features of the resulting gamma-ray emission. We performed 3-D magnetohydrodynamic simulations modeling the evolution of SN 1006 and its inter…
Multiple accelerated particle populations in the Cygnus Loop with Fermi-LAT
2021
The Cygnus Loop (G74.0-8.5) is a very well-known nearby supernova remnant (SNR) in our Galaxy. Thanks to its large size, brightness, and angular offset from the Galactic plane, it has been studied in detail from radio to $\gamma$-ray emission. The $\gamma$ -rays probe the populations of energetic particles and their acceleration mechanisms at low shock speeds. We present an analysis of the $\gamma$-ray emission detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope over 11 years in the region of the Cygnus Loop. We performed detailed morphological and spectral studies of the $\gamma$-ray emission toward the remnant from 100 MeV to 100 GeV and compared it with X-ra…
The NHXM observatory
2011
Exploration of the X-ray sky has established X-ray astronomy as a fundamental astrophysical discipline. While our knowledge of the sky below 10 keV has increased dramatically (∼8 orders of magnitude) by use of grazing incidence optics, we still await a similar improvement above 10 keV, where to date only collimated instruments have been used. Also ripe for exploration is the field of X-ray polarimetry, an unused fundamental tool to understand the physics and morphology of X-ray sources. Here we present a novel mission, the New Hard X-ray Mission (NHXM) that brings together for the first time simultaneous high-sensitivity, hard-X-ray imaging, broadband spectroscopy and polarimetry. NHXM will…
SHOCK-CLOUD INTERACTION AND PARTICLE ACCELERATION IN THE SOUTHWESTERN LIMB OF SN 1006
2014
The supernova remnant SN 1006 is a powerful source of high-energy particles and evolves in a relatively tenuous and uniform environment despite interacting with an atomic cloud in its northwestern limb. The X-ray image of SN 1006 reveals an indentation in the southwestern part of the shock front and the H I maps show an isolated (southwestern) cloud, having the same velocity as the northwestern cloud, whose morphology fits perfectly in the indentation. We performed spatially resolved spectral analysis of a set of small regions in the southwestern nonthermal limb and studied the deep X-ray spectra obtained within the XMM-Newton SN 1006 Large Program. We also analyzed archive H I data, obtain…