79 research outputs found
Precise and efficient modeling of stellar-activity-affected solar spectra using SOAP-GPU
No full textContext. One of the main obstacles in exoplanet detection when using the radial velocity (RV) technique is the presence of stellar activity signal induced by magnetic regions. As the most advanced techniques to mitigate this signal are reaching a level better than one meter per second, it is difficult to evaluate their performance: instrumental systematics start to be similar in magnitude, and therefore it is impossible to know the ground truth of the stellar activity signal. In this context, a realistic simulated dataset that can provide photometry and spectroscopic outputs is needed for method development.
Aims. The goal of this paper is to describe two realistic simulations of solar activity obtained from SOAP-GPU and to compare them with real data obtained from the HARPS-N solar telescope. For this purpose, both simulated spectral time series cover the time window of HARPS-N solar observation, but nothing prevents SOAP-GPU from modeling the data over different time spans.
Methods. We describe two different methods of modeling solar activity using SOAP-GPU. The first models the evolution of active regions based on the spot number as a function of time. Other physical parameters are either drawn from observed solar distributions or modeled with empirical relations. The second method relies on the extraction of active regions from the Solar Dynamics Observatory (SDO) data. The location of spots and faculae on the solar disk at each timestamp are derived from the magnetogram and intensity maps and are fed into SOAP-GPU to simulate the corresponding spectra.
Results. The simulated spectral time series generated with the first method shows a long-term RV behavior similar to that seen in the HARPS-N solar observations. The effect of stellar activity induced by stellar rotation is also well modeled with prominent periodicities at the stellar rotation period and its first harmonic. The comparison between the simulated spectral time series generated using SDO images and the HARPS-N solar spectra shows that SOAP-GPU can precisely model the RV time series of the Sun to a precision better than 0.9 m/s. By studying the width and depth variations of each spectral line in the HARPS-N solar and SOAP-GPU data, we find a strong correlation between the observation and the simulation for strong spectral lines, therefore supporting the modeling of the stellar activity effect at the spectral level. The correlations are weaker for shallow lines, although it is likely that their lower signal-to-noise ratio does not allow a meaningful comparison.
Conclusions. We introduce two methods for modeling solar activity using SOAP-GPU. With only sunspot numbers as input, we accurately capture the long-term magnetic cycle and rotational features. Additionally, we effectively model shift and depth variations at the spectral line level by using data from SDO. These simulated solar spectral time series serve as a useful test bed for evaluating spectral-level stellar activity mitigation techniques
Testing of pressure piezoelectric sensors: For Momo Medical
No full textIn this thesis, a test device is designed for the company Momo Medical. Momo Medical is developing a system that can be used to prevent pressure ulcers and adding more functionality is being investigated. For this system they need a device to test the functionality of the six piezoelectric sensors that are used in their product. The sensors’ response to a known pulse needs to be tested in order to give a pass/fail indication of the sensor quality. First, different ways of testing the sensors are investigated. Based on the results of the investigation, a final test setup is chosen and characterized. The test system developed in this thesis is based on a pneumatic setup, using a solenoid valve to control well-defined air pulses directed towards the sensors. Due to the addition of a reference load cell with custom designed read-out electronics, the device is able to test all six sensors one at the time and provides detailed feedback about the individual sensor quality. The test is performed using GUI-based software written in MATLAB, connected to a microcontroller. The software offers a broad variety of settings and can be configured according to Momo Medical’s wishes. After configuration, the test can be performed at the click of a button. The standard deviation of the device precision over three hours is sigma = 4.16, which equals a variation of cv = 0.82% of the mean μ = 504.8. This easily satisfies the requirements set byMomoMedical
High Precision Spectroscopy of the Solar Surface
No full textContext: High-precision spectroscopy of the resolved solar surface provides benchmark observations for a vast field of stellar research. The solar spectrum exhibits variations from the disc centre to the limb. Observing the solar disc for varying centre-to-limb positions includes observing changing layers of the solar atmosphere. Moreover, as the Sun is the only star spatially resolvable, it serves as an ideal testbed for investigating the behaviour of solar-like stars.
Aims: The primary goal of this thesis was to deliver a high-resolution spectroscopic centre-to-limb solar atlas with high-frequency precision and accuracy. Additionally, the varying convective Doppler velocities across the solar disc are investigated. The comprehensive objective was to enhance our understanding of the solar atmosphere and contribute to refining atmospheric models.
Methods: High-resolution observations of the resolved quiet Sun were examined with a Fourier transform spectrograph at the Institut für Astrophysik und Geophysik in Göttingen. The spectra contain a wavelength range from 4200Å to 8000Å, with a resolving power R of 700,000 at ~6000Å. The Doppler velocities of more than 1000 Fe I lines were determined across the solar disc with respect to line depth and the formation temperature.
Results & Conclusion: The resolved solar atlas contains 14 heliocentric positions from the centre to the limb. The achieved radial-velocity precision for the disc centre is about 0.6 m/s but varies with the centre-to-limb position. While the spectra of the IAG atlas align with earlier observations, they differ significantly from multiple simulations. In general, strong Fe I lines exhibit less blueshift than shallow lines; the strongest lines may even display a redshift. Additionally, the convective blueshift of Fe I lines decreases towards the limb. Lines with decreasing formation temperature show a corresponding decrease in blueshift. Doppler velocities, as a function of formation temperature, can be fitted by a sigmoid function, converging to stable temperatures. The wavelength dependency of Doppler velocities is more pronounced when considering line depth but is still present considering formation temperatures. This atlas offers numerous opportunities to enhance atmospheric models for the Sun or solar-like stars and can, therefore, even improve exoplanet detection.2024-06-2
Amor e um prato de momo: Traduções dos poemas de Tenzin Tseyang Gonsar
No full textO presente trabalho apresenta traduções poéticas de dois poemas da tibetana Tenzin Tseyang Gonsar: “Momo Love” (“Amor momo”) e “Momo burp” (“Arroto momo”) expressando, através de um prato típico, um sentimento de intimidade e familiaridade. As traduções são acompanhadas de informações sobre a autora, algumas interpretações possíveis dos poemas e o processo de tradução.This work presents poetic translations of two poems by the Tibetan poet Tenzin Tseyang Gonsar: “Momo Love” and “Momo burp” expressing, through a typical dish, a feeling of intimacy and familiarity. Both translations are followed by information on the author, some possible interpretations of the poems, and the process of translation. 
Letter from [Frank Chin] to Momo and Lawson, January 21, 1998
No full textA letter to Momo and Lawson, possibly from Frank Chin, about a performance of the story Kaguya Hime, princess of the moon in Japanese folklore. The purpose of the performance is to drum up interest for the children's storytelling event that would be part of the tribute to Michi Weglyn on February 21, 1998.These materials are from box 73 and 74 of the Frank Chin Papers. The Frank Chin Papers contain personal and professional correspondence between Frank Chin and Michi Weglyn relating to particular projects on which either author was working as well as files related to the Day of Remembrance Tribute to Michi Weglyn
Machiavelli e la maschera di Momo
No full textIl saggio propone una prima indagine sulla matrice lucianea dell’autoritratto che Niccolò Machiavelli compone attraverso l’epistolario e alcuni paratesti, e sulla possibile mediazione esercitata in questo senso dall’opera di Leon Battista Alberti. Soprattutto nel Prologo della Mandragola e nel I capitolo dell’Asino, ma anche nella precedente, celeberrima epistola a Francesco Vettori del 10 dicembre 1513, l’autore esibisce infatti una maschera molto somigliante a quella del Momo albertiano: irriverente, schiavo della sua stessa vocazione al ‘dir male’, vittima dell’ingratitudine dei potenti e capace di assumere – dalla distanza imposta con l’esilio – punti di vista dissacranti e rivelatori sulla realtà contemporanea.The essay proposes a first critical enquiry on the Lucian archetype of the self-portrait that Machiavelli fashions in his letters and in some paratextual writings, and on the possible mediation exercised in this sense by the work of Leon Battista Alberti. Especially in the Prologue of the Mandragola and in the first chapter of L’Asino, but also in the previous, famous epistle to Francesco Vettori of 10 December 1513, the author wears a ‘mask’ very similar to that of the Albertian Momo: irreverent, enthralled to his own compulsion to slander, victim of the ingratitude of the powerful and able to adopt – from the distance imposed with exile – a desecrating, yet revealing, point of view on contemporary reality
Momo Kapor: Magija Beograda - commented rendition of a narrative cycle
No full textShort story cycle Magija Beograda (2008, The Magic of Belgrade, Czech anthology Belgrade, my magic love!, 2014) is one of the last works of Serbian author Momo Kapor. His subject matter is contemporary picture of Belgrade and characters in his work are people, who are emotionally bound to this city. The aim of this dissertation is to introduce a Czech translation of the short stories and their translatological commentary. This work deals with the theme of Belgrade work of Kapor, which the author engaged in throughout his whole life and wrote in this style for more than ten years. This area of his work still does not have a Czech literary translation. This dissertation also brings more coherent author's portrait. Pivotal part consists of two chapters, first one is devoted to the profile of the author and the second one to the translation and commentary
La ritraduzione di Momo di Michael Ende. Un tentativo di riposizionamento
No full textThis article examines the changing reception of the German author Michael Ende in the Italian literary field through the various editions of his fantasy novel Momo (1973). A few years after the first translation by Silvia Stefani, published by Vallecchi (1974), the novel was entirely retranslated by Daria Angeleri, published by SEI (1981) and then reprinted several times by Longanesi. The Italian publishing history of the novel, accompanied by a contrastive analysis of the two translations, highlights the attempt to reposition the novel in a broader publishing context, free of generational barriers, to redefine the author’s literary status
La ritraduzione di Momo di Michael Ende. Un tentativo di riposizionamento
No full textThis article examines the changing reception of the German author Michael
Ende in the Italian literary field through the various editions of his fantasy novel Momo
(1973). A few years after the first translation by Silvia Stefani, published by Vallecchi
(1974), the novel was entirely retranslated by Daria Angeleri, published by SEI (1981) and
then reprinted several times by Longanesi. The Italian publishing history of the novel,
accompanied by a contrastive analysis of the two translations, highlights the attempt to
reposition the novel in a broader publishing context, free of generational barriers, to
redefine the author’s literary status
Polymeric Backbone Eutectogels as a New Generation of Hybrid Solid-State Electrolytes
No full textThis work introduces the polymeric eutectogel (P-ETG) solid composite electrolytes (SCEs) developed from the encapsulation of a liquid deep eutectic solvent (DES) electrolyte within a solid amide-based polymer backbone. Compared to their silica-based eutectogel counterparts, the P-ETGs can be efficiently processed by means of UV curing from liquid precursors and possess superior mechanical flexibility. The P-ETGs are characterized by a good electrochemical stability (up to 4.5 V vs Li) and high ionic conductivity up to 0.78 mS cm(-1). The potentiality of P-ETG for application in Li/Li-ion batteries is substantiated by stable cycling results of Li/P-ETG/LiFePO4 cells over 100 cycles at C/5 to 1C rates. The fire-hazards analysis reveals the improved safety of P-ETGs in contrast to the conventional liquid electrolytes (1 M LiPF6 in EC/DEC).B.J. was a Ph.D. research fellow of the Research Foundation Flanders (FWO Vlaanderen) for the duration of the conducted research and now a researcher at Hasselt University. This project receives the support of the European Union, the European Regional Development Fund ERDF [project 936], Flanders Innovation & Entrepreneurship, and the Province of Limburg. The authors thank A. Kelchtermans for help with the flammability tests, W. Maes for the use of the N2 glovebox and (ATR-)FT-IR setup, and W. Marchal, P. Samyn, and R. Carleer and group members for the many discussions on the (ATR-)FT-IR and TGA measurements.Joos, B; Hardy, AT (corresponding author), Hasselt Univ, B-3500 Hasselt, Belgium.
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