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Gotowa bibliografia na temat „Orbit, 1757”

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Data publikacji: 26 lipca 2024

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Artykuły w czasopismach na temat "Orbit, 1757"

Majeed, R. N., i S. A. El-Sheikh. "Fuzzy orbit topological spaces". IOP Conference Series: Materials Science and Engineering 571 (8.08.2019): 012026. http://dx.doi.org/10.1088/1757-899x/571/1/012026.

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Koryanov, Vsevolod V., i Budang Zhang. "Research on Coplanar Orbit Maneuvering in the Context of on-Orbit Service". IOP Conference Series: Materials Science and Engineering 630 (24.10.2019): 012001. http://dx.doi.org/10.1088/1757-899x/630/1/012001.

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Samoylov, A. G., S. A. Samoylov, S. A. Nasir i I. A. Al Tahar. "Radio links from low-orbit satellites". IOP Conference Series: Materials Science and Engineering 862 (28.05.2020): 022030. http://dx.doi.org/10.1088/1757-899x/862/2/022030.

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Alshamy, Hossam M. I., Ah El-S. Makled, Y. Elhalwagy i Hossam Hendy. "Flight dynamic model for low earth orbit satellites". IOP Conference Series: Materials Science and Engineering 610 (11.10.2019): 012100. http://dx.doi.org/10.1088/1757-899x/610/1/012100.

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Relangi, Naresh, Lakshmi Narayana Phaneendra Peri, Caio Henrique Franco Levi Domingos, Amalia Fossella, Julia Meria Leite Henriques i Antonella Ingenito. "Design of Supersonic and Hybrid engine based Advanced Rocket (SHAR)". IOP Conference Series: Materials Science and Engineering 1226, nr 1 (1.02.2022): 012031. http://dx.doi.org/10.1088/1757-899x/1226/1/012031.

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Abstract The paper deals with the design of a two-stage to orbit rocket launcher loaded with a solid rocket booster, scramjet, and hybrid rocket for delivering a 100kg payload in 200 km circular orbit. The possibility of implementing a cavity-based axisymmetric circular combustor in a scramjet is proposed. Computational analysis on various injector locations in a circular combustor and their validation with the test bench results were performed. The utilisation of a hybrid rocket in the final stage of the launcher to deliver the payload is discussed and the performance characteristics of the circular scramjet combustor and the hybrid rocket are shown. The overall mission proposed based on the sustainable and reusable characteristics.

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Jena, Soumyasree, i Sanjoy Datta. "Role of spin-orbit coupling in semimetallic bulk Bismuth". IOP Conference Series: Materials Science and Engineering 577 (7.12.2019): 012072. http://dx.doi.org/10.1088/1757-899x/577/1/012072.

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Li, H., M. Y. Zhou, S. Y. Wu i X. R. Liang. "Research of spin-orbit interaction in organic conjugated polymers". IOP Conference Series: Materials Science and Engineering 213 (czerwiec 2017): 012005. http://dx.doi.org/10.1088/1757-899x/213/1/012005.

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Cha, J., B. Carroll, J. Rodriguez, K. Maynard i M. Romero. "Thermal design and on-orbit performance of the ECOSTRESS instrument". IOP Conference Series: Materials Science and Engineering 755 (30.06.2020): 012005. http://dx.doi.org/10.1088/1757-899x/755/1/012005.

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Zhu, Lingchao, i Shuquan Wang. "Orbit-Attitude Coupled Tracking and Landing Control for an Asteroid". IOP Conference Series: Materials Science and Engineering 685 (22.11.2019): 012003. http://dx.doi.org/10.1088/1757-899x/685/1/012003.

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Zhang, Bin, Dongmei Wang, Yufeng Fan, Li Liu i Peirong Zhao. "In-orbit Failure Analysis and Verification for Thermistors outside Satellites". IOP Conference Series: Materials Science and Engineering 608 (27.08.2019): 012036. http://dx.doi.org/10.1088/1757-899x/608/1/012036.

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Rozprawy doktorskie na temat "Orbit, 1757"

Fugett, Daniel A. "Atomic Oxygen Considerations For LEO De-Orbit Trajectories Using Solar Sails". DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1756.

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Solar sails have the potential to benefit many future space exploration missions, but they lack the heritage required for present-day use. To grow confidence in solar sail technology, they could be deployed on LEO satellites higher than 600 km to help de-orbit the satellite within 25 years upon mission termination. To determine how atomic oxygen would affect the solar sail, material from Lightsail-2 was tested in a thermal-energy, isotropic, atomic oxygen vacuum chamber based in the space environments laboratory in California Polytechnic State University. The sail material, aluminized Mylar, was tested for its survivability on both the coated and uncoated side, as well as tested for the optical degradation of the coated side. The uncoated side was found to be completely eroded after a fluence of 2.27 x1020 atoms/cm2, or ~40 days in International Space Station orbit. The coated side experienced no mass loss, but signs of significant undercutting were found with a fluence of 1.19 x1021 atoms/cm2, or ~200 days at station orbit. The stitches present on the coated side, meant to prevent tear propagation, eroded before the sample experienced a fluence of 4.13 x1020 atoms/cm2, or ~70 days at station orbit. The average total reflectivity of the material dropped by ~5% after atomic oxygen exposure, however no correlation with fluence was found. Average specular reflectivity remained unchanged after atomic oxygen exposure. The reflectivity results were impacted by wrinkling in the material, which was found to have a much larger impact than atomic oxygen exposure. These results were paired with an optimal de-orbit trajectory algorithm, developed in this thesis, to determine how atomic oxygen would affect a solar sail deployed to de-orbit an 800 km LEO satellite with a ballistic coefficient of 0.1. Using a simplified 2D orbit case, it was found that the satellite would de-orbit within 12-18 years, depending primarily on the solar activity level. The measured worst-case for optical degradation increased de-orbit time by ~6 months. Additionally, assuming that the sail material was perfectly reflecting decreased de-orbit time by 2-4 years. The amount of fluence required to erode the uncoated Mylar, and the amount required to erode the stitches, were both reached long before the satellite re-entered. It is therefore recommended that the solar sail minimize uncoated side exposure to atomic oxygen, and a more atomic oxygen-resistant stitch material be found. The fluence required to produce significant material undercutting was reached only once the satellite’s orbit had degraded to below 400 km. But the undercutting was observed to structurally compromise the material; thus, future LEO solar sail mission designers must take care when balancing added performance with higher failure risk when considering the tension in the deployed sail.

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Van, Rensburg Helgard Marais. "An infrared earth horizon sensor for a LEO satellite". Thesis, Stellenbosch : University of Stellenbosch, 2008. http://hdl.handle.net/10019.1/1752.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2008.
Horizon sensing is an effective way to determine the pitch and roll of a LEO satellite and Earth horizon sensors that operate in the visible range of the electromagnetic spectrum are commonly used. These sensors have the disadvantage that they cannot operate when the satellite is in eclipse. Earth horizon sensors that operate in the infrared spectral range are a solution to take attitude measurements when the satellite is in eclipse. Until recently infrared detectors could only operate at very low temperatures and needed to be cryogenically cooled. The result was that their power consumption and physical characteristics (like dimensions and mass) were such that they were not suitable for use in small and medium LEO satellites. As a result of technology expansion in the field of infrared imagers the past few years, infrared imagers were developed which do not require cooling. The scope of this project was to develop and implement an Earth horizon sensor by using a low-cost, uncooled infrared imager. The performance and physical characteristics of various imager were evaluated and it was decided to select a low resolution thermopile imager mainly as a result of the cost limitations of the project. Software algorithms were then evaluated and selected for horizon detection and attitude determination. The Earth horizon sensor that was developed did not comply with the accuracy requirement (3s < 0.1o) that was set for the project because of the low resolution of the sensor. Methods to improve the accuracy were investigated and finally a sub-pixel edge estimation algorithm was developed and implemented which resulted in an improvement of 69% in the pitch accuracy and 49% in roll accuracy. With the sub-pixel edge estimation algorithm implemented the horizon sensor almost met the accuracy requirements (s < 0.0811o for pitch and s < 0.2944o for roll). This project confirms that, with further improvement to the design and test facilities, developing a low-cost, uncooled infrared Earth horizon sensor that meets the accuracy requirements is feasible.

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Heinze, Martin. "Spectrum and quantum symmetries of the AdS5 × S5 superstring". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17257.

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Die AdS/CFT-Dualität zwischen N=4 SYM und dem AdS_5 × S^5 Superstring zeigt Quanten-Integrabilität im planaren Limes und erlaubte die Konstruktion mächtiger Methoden, welche das Spektrale Problem zu lösen scheinen. Unser Verständnis der direkten Quantisierung des AdS_5 × S^5 Superstrings ist jedoch weiterhin unbefriedigend und besonders das Spektrum kurzer Stringzustände war bisher nur in führender Ordnung in starker ''t Hooft-Kopplung bekannt. In dieser Arbeit untersuchen wir verschiedene Methoden der perturbativen Quantisierung kurzer Strings über die führende Ordnung hinaus, wodurch wir uns auch einen besseres Verständnis der vorhandenen Quanten-Symmetrien erhoffen. Wir fokusieren auf die niedrigst angeregten Stringzustände, dual zum Konishi-Supermultiplet, und begutachten kritisch eine angeblichen Berechnung der Konishi anomalen Skalendimension im Pure-Spinor-Superstring-Formalismus. Als nächstes betrachten wir den bosonischen AdS_5 × S^5 String in statischer Eichung und konstruieren eine sog. Einzelmoden-Stringlösung, eine Veralgemeinerung des pulsierenden Strings durch unbeschränkte Nullmoden. Diese ist klassisch integrabel und quanteninvariant unter den Isometrien SO(2,4) × SO(6). Mögliche Korrekturen der vernachlässigten Supersymmetrie werden heuristisch berücksichtigt, wodurch die ersten Quantenkorrekturen der Konishi anomale Skalendimension reproduzieren werden. Wir implementieren statische Eichung für den AdS_5 × S^5 Superstring und finden elegante Ausdrücke für die Lagrangedichte und Superladungen. Unter Beschränkung auf das Superteilchen finden wir auf zwei unterschiedliche Arten kanonische Koordinaten in quadratischer Ordnung in Fermionen. Schließlich betrachten wir eine weitere Quantisierungsmethode: Da der Einzelmoden-String die SO(2,4) × SO(6)-Bahn des pulsierenden Strings ist, wenden wir Bahn-Methoden-Quantisierung auf das Teilchen und Spinning Strings in bosonischem AdS_3 × S^3 an und erhalten konsistente Ergebnisse für die Spektra.
The initial AdS/CFT duality pair, the duality between N=4 SYM and the AdS_5 × S^5 superstring, appears to enjoy quantum integrability in the planar limit, which allowed to devise powerful methods ostensibly solving the spectral problem. However, quantization of the AdS_5 × S^5 superstring from first principles is still an open question and especially the spectrum of short string states has previously been derived only at leading order in large ''t Hooft coupling. In this thesis we investigate possible routes to quantize short string states perturbatively beyond the leading order, where equally our aim is to gain better appreciation of the quantum symmetries at play. A prominent role is played by the lowest excited string states, dual to the Konishi supermultiplet, and we start by reviewing critically an asserted derivation of the Konishi anomalous dimension in the setup of pure spinor string theory. Next, we constrain ourselves to bosonic AdS_5 × S^5 String in static gauge, where we construct a so-called single-mode string solution, a generalization of the pulsating string allowing for unconstrained zero-modes. This solution shows classical integrability and invariance under the isometries SO(2,4) × SO(6) at the quantum level. Arguing heuristically about the effects of supersymmetry, we indeed recover the first non-trivial quantum correction to the Konishi anomalous dimension. We continue by implementing static gauge for the full AdS_5 × S^5 superstring and find elegant expressions for the Lagrangian density and the supercharges. We then constrain our interest to the superparticle and, using two different methods, find canonical coordinates at quadratic order in fermions. We conclude by exploring another quantization scheme: As the single-mode string is nothing but the SO(2,4) × SO(6) orbit of the pulsating string, we apply orbit method quantization to the particle and spinning string solutions in bosonic AdS_3 × S^3 yielding consistent results for the spectra.

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Regina, Christophe. "Femmes, violence(s) et sociéte face au tribunal de la sénéchaussée de Marseille (1750-1789)". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM3022.

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Les femmes sont-elles violentes ? Simple question qui appelle a priori une réponse évidente mais qui dans les faits semble avoir quelques difficultés à retrouver une réponse. Vision biaisée, regards troublés, les lectures du rapport des femmes à la violence tendent à réduire, à minimiser ou à réfuter l'exercice quotidien d'une violence féminine renvoyée à l'exceptionnel et à l'anormalité. Les femmes seraient par définition moins violentes que les hommes. Mais quels sont les fondements de pareil postulat ? Afin d'y réfléchir ont été investies dans le cadre de cette thèse les archives du tribunal de la sénéchaussée de Marseille afin de questionner les formes, les occasions et les expériences de la violence ordinaire auxquelles les femmes étaient confrontées. Se défaisant de l'idée d'un phénomène jugé mineur et ponctuel, les sources exploitées ont permis d'appréhender l'ordinaire des violences marseillaises, resituant aux sexes la part respective qui leur revient en la matière et permettant de nuancer l'idée d'une faible participation féminine aux actes violents ainsi qu'une réflexion sur les formes et manifestations des violences. Les femmes tout à tour actrices et victimes de ces usages tiennent une place fondamentale au sein de la société des voisins qu'elles envahissent, modèlent et contrôlent en partie. La litigiosité féminine a constitué l'angle d'approche retenu pur considérer au travers du regard judiciaire et de ses imperfections, le quotidien ordinaire d'une ville importante d'Ancien Régime : Marseille. La violence est processeur d'une dynamique sociale à laquelle les femmes prennent activement part, qu'elle la subissent ou qu'elles l'exercent
Are Women violent? The answer to this simple question would seem a priori obvious, but in fact it is difficult to offer a convincing explanation. Statistics and data on female violence tend to reduce, minimize or disprove the idea that female violence might take place on a daily basis, suggesting rather that it is the exception, or at the very least an abnormal occurrence. Apparently, women are inherently less violent than men. But what is the basis for such a premise? In order to answer this question, we have studied the records of the Seneschal of Marseilles' court. These judicial archives allow us to understand the forms, opportunities and experience of everyday violence that women faced. Setting aside the idea that this was a minor and irregular phenomenon, these sources provide evidence of violence in the everyday life of Marseilles' inhabitants and attribute to each sex their proper place in this behavior, while enabling a nuanced analysis of the idea that women were less inclined to violence and providing insight into the forms and manifestations of such violence. Women, both actresses and victims of these practices, were key players within the society in their ability to enter, shape and partially control their neighbourhood. By studying cases presented to the courts by women, it is possible to adopt the judge's perspective, with its insight and imperfections, of daily life of a major city under the Old Regime: Marseilles. Violence was a social dynamic process in which women were actively involved, whether as victims or aggressors. By comparing analytical tools and approaches of sources, it is possible to study both the working and the elite classes

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Książki na temat "Orbit, 1757"

Breslaw, Elaine G. Dr. Alexander Hamilton and provincial America: Expanding the orbit of Scottish culture. Baton Rouge: Louisiana State University Press, 2007.

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Breslaw, Elaine G. Dr. Alexander Hamilton and Provincial America: Expanding the Orbit of Scottish Culture (Southern Biography Series). Louisiana State University Press, 2008.

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Robinson, Percy. Handel and His Orbit. Creative Media Partners, LLC, 2022.

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Robinson, Percy. Handel and His Orbit. Creative Media Partners, LLC, 2018.

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Części książek na temat "Orbit, 1757"

Fisher, John. "The Triumph of Themistocles". W The Life and Work of James Bradley, 239–69. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198884200.003.0009.

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Abstract Bradley first revealed his observations of the nutation of the Earth’s axis to Maupertuis in 1737, after observing it at Wanstead since 1727. He published his paper on the nutation in 1748 after he had observed the phenomenon through a complete retrogression of the nodes of the lunar orbit around the Earth. By eighteenth century standards the phenomenon, followed via the senses was infinitesimal, so much so that Edmond Halley, Bradley’s mentor, never accepted that such highly precise observations were possible. The Newtonian approach to making new knowledge claims based on observation and experiment was more successful than the Cartesian approach to knowledge claims based on first principles. It was the precision of George Graham’s instruments that made the discovery of nutation possible.

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Schwartz, Richard Evan. "The Orbit Equivalence Theorem". W The Plaid Model, 173–84. Princeton University Press, 2019. http://dx.doi.org/10.23943/princeton/9780691181387.003.0018.

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This chapter begins Part 4 of the monograph. The goal of this part is to prove the Orbit Equivalence Theorem and the Quasi-Isomorphism Theorem. Theorem 17.1 (Orbit Equivalence) states that there is a dynamically large subset Z ⊂ X and a map Ω‎: Z → Y. Section 17.2 defines Z. Section 17.3 defines Ω‎. Section 17.4 characterizes the image Ω‎(Z). Section 17.5 defines a partition of Z into small convex polytopes which have the property that all the maps in Equations 17.1 and 1 are entirely defined and projective on each polytope. This allows us to verify the properties in the Orbit Equivalence Theorem just by checking what the two relevant maps do to the vertices of the new partition. Section 17.6 puts everything together and prove the Orbit Equivalence Theorem modulo some integer computer calculations. Section 17.7 discusses the computational techniques used to carry out the calculations from Section 17.6. Section 17.8 explains the calculations.

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Douglas, Bronwen. "‘Novus Orbis Australis’: Oceania in the science of race, 1750–1850". W Foreign Bodies: Oceania and the Science of Race 1750–1940. ANU Press, 2008. http://dx.doi.org/10.22459/fb.11.2008.03.

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Streszczenia konferencji na temat "Orbit, 1757"

Rudolph, Andreas, Dave Milligan, Gary Whitehead, Frederico di Marco, Peter Collins, Edmund Serpell, Jonas Marie, W. O'Mullane, Giuseppe Sarri i Robert Furnell. "Gaia Mission Operations Concept and Launch and Early Orbit Phase - In-Orbit Experience". W SpaceOps 2014 Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2014. http://dx.doi.org/10.2514/6.2014-1751.

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Davis, Diane C., Emily M. Zimovan-Spreen, Rolfe J. Power i Kathleen C. Howell. "Cubesat Deployment from a Near Rectilinear Halo Orbit". W AIAA SCITECH 2022 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2022. http://dx.doi.org/10.2514/6.2022-1777.

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Misra, Gaurav, i Amit K. Sanyal. "Analysis of Orbit-Attitude Coupling of Spacecraft Near Small Solar System Bodies". W AIAA Guidance, Navigation, and Control Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-1777.

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Davis, Bruce, Dana Turse i William H. Francis. "The Deployment of Large De-Orbit Sails Utilizing High Strain Composite Booms". W AIAA Scitech 2019 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-1750.

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Muhammed, Ameen R. A., i Dara W. Childs. "Vibration Modeling and Experimental Results of Two Phase Flow Twin-Screw Pump". W ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-44115.

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In turbomachines, the transfer of energy between the rotor and the fluid does not — in theory — result in lateral forces on the rotor. In positive displacement machines, on the other hand, the transfer of energy between the moving and stationary components usually results in unbalanced pressure fields and forces. In [1] the authors developed a model to predict the dynamic forces in twin screw pumps, showing that the helical screw shape generates hydraulic forces that oscillate at multiples of running speed. The work presented here attempts to validate the model in [1] using a clear-casing twin screw pump. The pump runs in both single and multiphase conditions with exit pressure up to 300 KPa and a flow rate 0.6 liter per second. The pump was instrumented with dynamic pressure probes across the axial length of the screw in two perpendicular directions to validate the dynamic model. Two proximity probes measured the dynamic rotor displacement at the outlet to validate the rotordynamics model and the hydrodynamic cyclic forces predicted in [1]. The predictions were found in good agreement with the measurements. The amplitude of the dynamic pressure measurements in two perpendicular plans supported the main assumptions of the model (constant pressure inside the chambers and linear pressure drop across the screw lands). The predicted rotor orbits at the pump outlet in the middle of the rotor matched the experimental orbits closely. The spectrum of the response showed harmonics of the running speed as predicted by the model. The pump rotor’s calculated critical speed was at 24.8 krpm, roughly 14 times the rotor’s running speed of 1750 rpm. The measured and observed excitation frequencies extended out to nine times running speed, still well below the 1st critical speed. However, for longer twin-screw pumps running at higher speed, the coincidence of a higher-harmonic excitation frequency with the lightly damped 1st critical speed should be considered.

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Panicucci, Paolo, Eleonora Andreis, Fabio Ornati i Francesco Topputo. "Towards Validation and Verification of Autonomous Vision-Based Navigation for Interplanetary Spacecraft". W ESA 12th International Conference on Guidance Navigation and Control and 9th International Conference on Astrodynamics Tools and Techniques. ESA, 2023. http://dx.doi.org/10.5270/esa-gnc-icatt-2023-112.

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Abstract The number of spacecraft launched per year is increased dramatically in the last decades granting access to private companies and public actors. Space assets are becoming crucial to asses disaster monitoring, precise agriculture, and global network interconnections. This trend is not limited to Earth observation applications, but it extends beyond Earth's orbit to support space exploration and exploitation. The current paradigm to operate interplanetary spacecraft strongly relies on the Deep-Space Network (DSN) which communicates with the spacecraft to obtain range and range-rate measurements. These data are then processed by large teams of engineers on ground to solve the orbit determination problem and the required maneuvers. Although this process is extremely precise and has been used since the beginning of space exploration, the increasing number of spacecraft and the riskier operations needed to support compelling science are making it outdated. First, the DSN has a limited number of communication slots which implies that a small number of spacecraft can be operated. Second, the process is extremely costly as large teams of individuals are involved in it. Finally, the delayed communications between the spacecraft and the ground station make some operations, such as landing or sampling, infeasible as the spacecraft does not have the needed reactivity. Because of these reasons, autonomous navigation is becoming a crucial technology for present and future missions. Among all the navigation sensors, cameras are generally preferred because they are light, compact, and low-priced. For this reason, Vision-Based Navigation (VBN), i.e., the combination of camera and image processing (IP) algorithms, is generally employed as an autonomous solution to solve the navigation problem. When a spacecraft is on an interplanetary cruise, it can determine its position by using known planet position within the Solar System. When the planet lines of sight (LoS) measurements are available, the spacecraft can triangulate its position in the inertial reference frame by knowing the planet ephemeris. This can be performed statically [1, 2], when more than one planet is available, or dynamically, by providing the LoSes measurements history to a navigation filter [3, 4]. The planet LoS determination can be performed by extracting the planet position from images by performing attitude determination and by knowing the planet ephemeris [5, 6]. This is a fully autonomous solution as the spacecraft does not require any piece of information from ground. The proposed solution is thus composed of an IP pipeline, which determines autonomously its attitude and extracts the planet LoSes, and a navigation filter, which determines the spacecraft state by taking into account light aberrations [7]. An important step to be performed is the algorithm validation process which is generally performed by increasing the simulation framework complexity and by including hardware-in-the-loop (HIL) components. Andreis et al. [4] develops and analyses the navigation filtering strategy to be deployed on board by assuming IP behavioral model, while Andreis et al. [6] and Andreis et al. [5] develop the IP pipeline and test it on synthetic images from a custom-designed rendering engine [8]. Andreis et al. [7] further develop the VBN algorithm by proposing an integrated solution to compensate for light aberrations. Finally, Panicucci et al. [9] assesses the IP performances on images acquired on RETINA, a HIL optical navigation test bench. In this context, a high-resolution screen stimulates a camera to acquire images as they would be taken in orbit. Standing on previous work, this paper presents the validation of the VBN algorithm on HIL simulation. First, a series of images are acquired on RETINA by simulating the reference trajectory and the attitude profile of the spacecraft. These images are processed sequentially by the VBN algorithm. Spacecraft state estimates are compared against the true value to assess navigation accuracy. Acknowledgments This research is part of EXTREMA, a project that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 864697). References [1] V. Franzese and F. Topputo. Optimal beacons selection for Deep-Space optical navigation. The Journal of the Astronautical Sciences, 67(4):1775–1792, 2020. doi: 10.1007/s40295-020-00242-z. [2] S. B. Broschart, N. Bradley, and S. Bhaskaran. Kinematic approximation of position accuracy achieved using optical observations of distant asteroids. Journal of Spacecraft and Rockets, 56 (5):1383–1392, 2019. doi: 10.2514/1.A34354. [3] R. R. Karimi and D. Mortari. Interplanetary autonomous navigation using visible planets. Journal of Guidance, Control, and Dynamics, 38(6):1151–1156, 2015. doi: 10.2514/1.G000575. [4] E. Andreis, V. Franzese, and F. Topputo. Onboard Orbit Determination for Deep-Space CubeSats. Journal of Guidance, Control, and Dynamics, pages 1–14, 2022. doi: 10.2514/1.G006294. [5] E. Andreis, P. Panicucci, and F. Topputo. An Image Processing Pipeline for Autonomous Deep-Space Optical Navigation. Journal of Spacecraft and Rockets, Under Review. [6] E. Andreis, P. Panicucci, V. Franzese, and F. Topputo. A Robust Image Processing Pipeline for Planets Line-Of-sign Extraction for Deep-Space Autonomous Cubesats Navigation. In 44th AAS Guidance, Navigation and Control Conference, pages 1–19, 2022. [7] E. Andreis, P. Panicucci, V. Franzese, and F. Topputo. A Vision-Based Navigation algorithm for Autonomous Deep-Space Cruise. In 3rd Space Imaging Workshop, 2022. [8] S. Bella, E. Andreis, V. Franzese, P. Panicucci, and F. Topputo. Line-of-Sight Extraction Algorithm for Deep-Space Autonomous Navigation. In 2021 AAS/AIAA Astrodynamics Specialist Conference, pages 1–18, 2021. [9] P. Panicucci, Andreis E., V. Franzese, and F. Topputo. An Overview of the EXTREMA Deep-Space Optical Navigation Experiment. In 3rd Space Imaging Workshop, 2022.

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Vance, John M., J. J. Zierer i E. M. Conway. "Effect of Straight Through Labyrinth Seals on Rotordynamics". W ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0190.

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Abstract Experimental measurements have been made to evaluate the rotordynamic performance of straight-through labyrinth seals under conditions that are realistic for many turbomachines. Both teeth-on-rotor and teeth-on-stator gas seals were tested, each with twelve blades, 173 mm (6.8″) blade diameter, and 102 mm (4″) total length. The nominal blade tip clearance was 0.5 mm (20 mils). The teeth-on-stator seal was tested with the blade tip clearances diverging (in the direction of the flow), uniform, and converging. The teeth-on-rotor seal was tested with uniform clearances. The inlet air pressure to the seals was varied from 1.7 bar to 14.6 bar (25 psi to 200 psig) with the last blade exhausting to the atmosphere. Coastdown tests of all the seals were performed on a rotordynamic test rig to show their effect on synchronous response to imbalance when passing through a 3700 rpm critical speed. For the teeth-on-rotor seal, rap tests at 4500 rpm were also conducted to measure the effective damping coefficient for subsynchronous vibration. The synchronous response to imbalance was generally increased by all the seals at inlet pressures up to about 11.2 bar (150 psig). The worst case was for the teeth-on-rotor seal at about 2.7 bar (35–45 psi) inlet pressure where the rotor whirl amplitude was increased from .1 mm (3.75 mils, peak to peak) to over .13 mm (5 mils). In most cases the rotor whirl amplitude was slightly decreased at inlet pressures above 13 bar (176 psig). The teeth-on-rotor seal provided a small amount of damping to attenuate the 61 Hz subsynchronous vibration with the rotor running at 4500 rpm. A computer model which includes both the rotor and housing dynamics was developed to evaluate the possible range of values of the rotordynamic seal coefficients. Simulations show that the effective subsynchronous damping coefficient of the teeth-on-rotor seal ranges from 175 N-s/m at 5.1 bar inlet pressure (1 lb-s/in at 75 psi) to 876 N-s/m at 10.2 bar (5 lb-s/in at 150 psi). This corresponds to a range of 0.3% to 1.4% of critical damping added by the seal for subsynchronous vibration, even though the seal increased the synchronous response at the critical speed. It is shown that the orbit conditions for the synchronous and subsynchronous tests were radically different, as they likely will be in most turbomachines.

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Raporty organizacyjne na temat "Orbit, 1757"

Health hazard evaluation report: HETA-86-277-1750, Project Orbis, Inc., New York, New York. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, listopad 1986. http://dx.doi.org/10.26616/nioshheta862771750.

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