21549 research outputs found
Sort by
Étude des effets tranquillisants de la gabapentine chez le chat stressé lors d'une consultation de médecine préventive
Get PDFDe nos jours, de nombreux chats ne sont toujours pas médicalisés à cause du stress trop important qu’engendre une visite vétérinaire. Étant un animal territorial le changement d’environnement et sa manipulation représentent de grandes sources de stress. La gabapentine, à l’origine utilisée chez l’Homme, semble avoir de multiples intérêts chez le chat, dont un effet tranquillisant. Cette étude a pour but de répertorier les connaissances actuelles sur la gabapentine, et d’identifier ses effets sur le chat stressé en consultation de médecine préventive pour déterminer son intérêt d’utilisation. Six chats ont été observés lors d’une consultation avec et sans gabapentine, montrant un comportement amélioré ou identique lors de son administration. Aucun effet indésirable n’a été observé. Les résultats de cette étude, en accord avec la littérature semblent indiquer que le rapport bénéfice-risque de l’utilisation de la gabapentine est favorable chez le chat adulte sain lors de stress
Effects of dynamics and trigger on energy absorption of composite tubes during axial crushing
Get PDFThe purpose of this study is to complete a previous quasi-static experimental campaign on the energy absorption performance of composite tubes with the influence of the dynamic effect. Various hybrid composite tubes, involving unidirectional and braided plies with various materials and stacking sequences, were tested both in quasi-static and in dynamic crushing in order to identify their behavior and determine their absorbing capabilities using the Specific Energy Absorption. In dynamic loading, 90°-oriented fibers stabilised by woven plies showed good performances, contrary to static loading, since the energy absorption of the unidirectional laminate oriented at 0° drops by 50% in dynamics
The Site Tilt and Lander Transfer Function from the Short-Period Seismometer of InSight on Mars
No full textThe National Aeronautics and Space Administration InSight mission has deployed the seis-
mic experiment, SEIS, on the surface of Mars, and has recorded a variety of signals includ-
ing marsquakes and dust devils. This work presents results on the tilt and local noise
sources, which provide context to aid interpretation of the observed signals and allow
an examination of the near-surface properties. Our analysis uses data recorded by the
short-period sensors on the deck, throughout deployment and in the final configuration.
We use thermal decorrelation to provide an estimate of the sol-to-sol tilt. This tilt is exam-
ined across deployment and over a Martian year. After each modification to the site, the tilt
is seen to stabilize over 3–20 sols depending on the action, and the total change in tilt is <
0.035°. Long-term tilt over a Martian year is limited to < 0.007°. We also investigate the
attenuation of lander-induced vibrations between the lander and SEIS. Robotic arm
motions provide a known lander source in the 5–9 Hz bandwidth, yielding an amplitude
attenuation of lander signals between 100 and 1000 times. The attenuation of wind sen-
sitivity from the deck to ground presents a similar value in the 1.5–9 Hz range, thus favor-
ing a noise dominated by lander vibrations induced by the wind. Wind sensitivities outside
this bandwidth exhibit different sensitivity changes, indicating a change in the coupling.
The results are interpreted through a finite-element analysis of the regolith with a depth-
dependent Young’s modulus. We argue that discrepancies between this model and the
observations are due to local compaction beneath the lander legs and/or anelasticity.
An estimate for the effective Young’s modulus is obtained as 62–81 MPa, corroborating
previous estimates for the top layer duricrust
Autocorrelation of the Ground Vibrations Recorded by the SEIS‐InSight Seismometer on Mars
Get PDFSince early February 2019, the SEIS (Seismic Experiment for Interior Structure)
seismometer deployed at the surface of Mars in the framework of the InSight mission has been
continuously recording the ground motion at Elysium Planitia. In this study, we take advantage of this
exceptional data set to put constraints on the crustal properties of Mars using seismic interferometry (SI).
To carry out this task, we first examine the continuous records from the very broadband seismometer.
Several deterministic sources of environmental noise are identified and specific preprocessing strategies
are presented to mitigate their influence. Applying the principles of SI to the single-station configuration
of InSight, we compute, for each Sol and each hour of the martian day, the diagonal elements of the
time-domain correlation tensor of random ambient vibrations recorded by SEIS. A similar computation
is performed on the diffuse waveforms generated by more than a hundred Marsquakes. A careful signal-
to-noise ratio analysis and an inter-comparison between the two datasets suggest that the results from
SI are most reliable in a narrow frequency band around 2.4 Hz, where an amplification of both ambient
vibrations and seismic events is observed. The average autocorrelation functions (ACFs) contain well
identifiable seismic arrivals, that are very consistent between the two datasets. Interpreting the vertical
and horizontal ACFs as, respectively, the P- and S- seismic reflectivity below InSight, we propose a simple
stratified velocity model of the crust, which is mostly compatible with previous results from receiver
function analysis. Our results are discussed and compared to recent works from the literature
The Marsquake catalogue from InSight, sols 0–478
Get PDFThe InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission began
collecting high quality seismic data on Mars in February 2019. This manuscript documents the seismicity ob
served by SEIS, InSight's seismometer, from this time until the end of March 2020. Within the InSight project, the
Marsquake Service (MQS) is responsible for prompt review of all seismic data collected by InSight, detection of
events that are likely to be of seismic origin, and curation and release of seismic catalogues. In the first year of
data collection, MQS have identified 465 seismic events that we interpret to be from regional and teleseismic
marsquakes. Seismic events are grouped into 2 different event families: the low frequency family is dominated by
energy at long period below 1 s, and the high frequency family primarily include energy at and above 2.4 Hz.
Event magnitudes, from Mars-specific scales, range from 1.3 to 3.7. A third class of events with very short
duration but high frequency bursts have been observed 712 times. These are likely associated with a local source
driven by thermal stresses. This paper describes the data collected so far in the mission and the procedures under
which MQS operates; summarises the content of the current MQS seismic catalogue; and presents the key fea
tures of the events we have observed so far, using the largest events as examples
Function to Form Mapping and Search for Civil Aeroplane Energy Efficiency
Get PDFThe contemporary debate on the need for the civil aeronautical industry to reconcile its global warming impact and the continuous air traffic growth is gaining in prominence. While solutions exist to tackle different aspects of this complex problem individually, the core of the response lies in rethinking the conventional aeroplane architecture in order to reach new energy efficiency optima. This paper presents a function-to-form framework used for describing different aspects of architectural design of an aeroplane as technological system. Firstly, a brief overview of different existing ways to improve aeroplane architectures is given. With that background, a preliminary definition of multi-level system composition of an aeroplane is presented. A physics-based framework is then correlated to the Functional, Behavioural, Structural and Experiential requirement framework, in order to characterise the different physical phenomena experienced by an aeroplane for a single operating point. These provide basis for definition of a qualitative figure of merit dubbed Integration Potential of an architecture, which serves as proxy for describing function-to-form mapping of aeroplane system architectures. Using both the historical, contemporary and projected tendencies of aeroplane technology advances, existence of an asymptotic limit of this parameter is inferred. This limit arguably indicates the extent to which it could still be possible to go in search for energy efficiency gains by virtue of system architecture design
Questions to Heaven: InSight's attempted detection of Zhurong's arrival at Mars
No full textBenjamin Fernando and colleagues report on the international cooperation involved InSight's attempt to gather seismic data from the arrival at Mars of China's Zhurong rover
How to better identify and mitigate risks in call for tenders: towards a dedicated risk ontology
Get PDFWhen preparing a commercial offer concerning technical systems, suppliers working in engineer to order can either make a detailed design job or just decide key solution choices. With a detailed design, if the customer accepts the offer, the supplier has a good confidence in its ability to provide a solution matching offer contents because requirements have been studied in details. With key technical choices, it is not the case, and the supplier takes the risk of not being able to provide an adequate solution because requirements have been just superficially studied. The goal of the communication is to propose and discuss the key knowledge elements in order to manage this kind of supplier risk when preparing the offer. By management we mean, according to ISO 31000, identifying, assessing and processing risk. The proposed key knowledge elements are a risk taxonomy and a risk mitigation action taxonomy. Actually, risk management relies fully on human expertise, these modeling elements will allow companies to design a knowledge-based system that can assist the human in charge and improve commercial offers quality
Surface roughness perfection by CAM interpolations
Get PDFThe surface quality of the parts is one of the major objectives of the use of the high-speed milling (HSM). Tool path interpolations affect the machining operation of complex parts in HSM. In this paper, the influence of the different types of interpolation of the computer-aided manufacturing (CAM) on the surface roughness in the HSM machining of free forms is studied. To do this, a simulation tool of the surface texture for each type of interpolation is proposed. Then, experimental measurements expressing surfaces condition are carried out. To validate our approach, theoretical results with experimental ones are compared. As results, CAM interpolations of tool paths have demonstrated an important impact on the surface texture. In fact, a simulation prediction tool has confirmed the advantages of using polynomial interpolations in order to
ameliorate the quality of the machined surface
Développement d'une méthode d'analyse du taux de mutation de l'hémagglutinine des virus influenza.
Get PDFLes virus influenza aviaires hautement pathogènes représentent un enjeu majeur à la fois économique ainsi que pour la santé animale et humaine. Actuellement, nous sommes incapables de prédire l’émergence de ces virus. Il est donc nécessaire de comprendre comment ces virus émergent et notamment comment leur hémagglutinine acquière un site de clivage polybasique. Dans ce travail, nous avons construit un plasmide permettant l’insertion d’une séquence d’hémagglutinine, à la suite de celle codante pour le gène de la protéine acide PA d’un virus influenza H7N1. Ce plasmide peut ensuite être utilisé en génétique inverse pour produire des virus possédant ce transgène, qui ne sera pas traduit et pourra donc accumuler toutes les mutations lors de la réplication virale, même celles habituellement délétères pour l’hémagglutinine. Ce système représente un outil important pour l’étude de l’impact de la séquence nucléotidique de l’hémagglutinine sur son taux de mutation ainsi que celui de sa structure secondaire, notamment dans la région du site de clivage