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1
Wakley, Glenn Keith. « Space flight and bone ». Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246296.
Texte intégral
2
Shebanits, Oleg. « Pre-biotic molecules and dynamics in the ionosphere of Titan : a space weather station perspective ». Licentiate thesis, Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-248118.
Texte intégralRésumé :
Saturn’s largest moon Titan (2575 km radius) is the second largest in the Solar system. Titan is the only known moon with a fully developed nitrogen-rich atmosphere with ionosphere extending to ~2000 km altitude, hosting complex organic chemistry. One of the main scientific interests of Titan’s atmosphere and ionosphere is the striking similarity to current theories of those of Earth ~3.5 billion years ago. The Cassini spacecraft has been in orbit around Saturn since 2004 and carries a wide range of instruments for investigating Titan’s ionosphere, among them the Langmuir probe, a “space weather station”, manufactured and operated by the Swedish Institute of Space Physics, Uppsala. This thesis reviews the first half of the PhD project on the production of pre-biotic molecules in the atmosphere of Titan and early Earth, focusing on the ion densities and dynamics in Titan’s ionosphere derived from the in-situ measurements by the Cassini Langmuir probe. One of the main results is the detection of significant, up to ~2300 cm-3, charge densities of heavy (up to ~13000 amu) negative ions in Titan’s ionosphere below 1400 km altitude. On the nightside of the ionosphere at altitudes below 1200 km, the heavy negative ion charge densities are comparable to the positive ion densities and are in fact the main negative charge carrier, making this region of the ionosphere exhibit properties of dusty plasma. The overall trend is the exponential increasing of the negative ion charge densities towards lower altitudes. Another important result is the detection of ion drifts that between 880-1100 km altitudes in Titan’s ionosphere translate to neutral winds of 0.5-5.5 km/s. Ion drifts define three regions by altitude, the top layer (above ~1600 km altitude) where the ions are frozen into the background magnetic field, the dynamo region (1100 – 1600 km altitudes) where the ions are drifting in partly opposing directions due to ion-neutral collisions in the presence of the magnetic and electric fields and the bottom layer (below 1100 km altitude) of the ionosphere, where the ions are coupled to neutrals by collisions.
3
Curry, Diarmuid. « Data Acquisition Blasts Off - Space Flight Testing ». International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/606142.
Texte intégralRésumé :
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, NevadaIn principle, the requirements for a flight test data acquisition system for space testing (launch vehicles, orbiters, satellites and International Space Station (ISS) installations) are very similar to those for more earth-bound applications. In practice, there are important environmental and operational differences that present challenges for both users and vendors of flight test equipment. Environmental issues include the severe vibration and shock experienced on take-off, followed by a very sharp thermal shock, culminating (for orbital vehicles) in a low temperature, low pressure, high radiation operating environment. Operational issues can include the need to dynamically adapt to changing configurations (for example when an instrumented stage is released) and the difficulty in Telemetering data during the initial launch stage from a vehicle that may not be recoverable, and therefore does not offer the option of an on-board recorder. Addressing these challenges requires simple, rugged and flexible solutions. Traditionally these solutions have been bespoke, specifically designed equipment. In an increasingly cost-conscious environment engineers are now looking to commercial off-the-shelf solutions. This paper discusses these solutions and highlights the issues that instrumentation engineers need to consider when designing or selecting flight test equipment.
4
Upshaw, Kathy Suzanne. « Long duration manned space flight systems considerations ». Master's thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12232009-020150/.
Texte intégral
5
Leung, Tonny. « Human space flight training centre a cradle for preparation of future space exploration / ». Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31987163.
Texte intégral
6
Leung, Tonny, et 梁啟東. « Human space flight training centre : a cradle for preparation of future space exploration ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31987163.
Texte intégral
7
Holland, Dwight A. « Systems and human factors concerns for long-duration spaceflight ». Master's thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01202010-020232/.
Texte intégral
8
Guidi, Mark Arthur. « Human factors implications of psychological stress in long duration space flight ». Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03302010-020138/.
Texte intégral
9
Alves, Daniel F. Jr. « Space-Based Flight Termination System Incorporating GPS Telecommand Link ». International Foundation for Telemetering, 1997. http://hdl.handle.net/10150/609823.
Texte intégralRésumé :
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper will investigate the areas which must be addressed to implement a truly integrated Range instrumentation system on a GPS-based Range, using a patented L-Band commanding scheme. Hardware issues will be highlighted as well the issues to be addressed in changing from an audio tone-frequency modulated command system to a digital system incorporating encryption and spread spectrum. Some thoughts addressing costs and schedule to incorporate this approach into the architecture of the U. S. Air Force Range Standardization and Automation (RSA) architecture, as a candidate GPS-based Range are also presented, as well as a discussion of the benefits to be accrued over the existing system, if this approach were adopted.
10
O'Brien, Robin A. « Generic Decommutation Capabilities in the Space Flight Operations Center ». International Foundation for Telemetering, 1988. http://hdl.handle.net/10150/615254.
Texte intégralRésumé :
International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaA generic decommutation capability has been created as part of the Space Flight Operation Center's goal of developing a multi-mission telemetry system. Generic decommutation involves separating the algorithmic description for extracting data from the actual implementation of decommutation. This was done by creating a Decommutation Map Language, which allows mission designers to describe decommutation algorithms without the restrictions imposed by a standard programming language. A Decommutation Map Compiler converts this description into C code, which is then linked with a decommutation library to provide an executable decommutation program. So far, this approach has been used successfully to decommutate several different types of data.
11
Goodman, Ross V. « Space Flight Operations Center Local Area Network : Hardware Design ». International Foundation for Telemetering, 1988. http://hdl.handle.net/10150/615256.
Texte intégralRésumé :
International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaThe existing Mission Control and Computer Center at JPL will be replaced by the Space Flight Operations Center (SFOC). One part of the SFOC is the Local Area Network-Based Distribution System. The purpose of the Local Area Network (LAN) is to distribute the processed data among the various elements of the SFOC. The SFOC LAN will provide a robust subsystem that will support the Magellan launch configuration and future project adaptations with the following capabilities: * A proven cable medium (Ethernet) as the backbone for the entire network, with capability for migration to a fiber optics backbone in the future. * Choice of hardware components that are reliable, varied, and supported by companies that are following the growth path of the ISO model (OSI Standards). * Insure a reliable and maintainable network for SFOC-supported projects. * Accurate and detailed documentation of the LAN, valuable for fault isolation and future expansion of the network. * Proven network monitoring and maintenance tools.
12
Halter, Ronald Vaughn. « A universal time of flight equation for space mechanics ». Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43406.
Texte intégralRésumé :
A universal time of flight equation for any orbit is developed as a
function of the initial and final radius, the change in true anomaly
and the initial flight path angle. Lambert's theorem, a new corollary
to this theorem, a trigonometric variable substitution and a continuing
fraction expression are used in this development. The resulting
equation is not explicitly dependent upon eccentricity and is
determinate for -2n < (change in true anomaly) < 2n. A method to
make the continuing fraction converge rapidly is evaluated using a top
down algorithm. Finally, the accuracy of the universal time of flight
equation is examined for a representative set of orbits including near
parabolic and near rectilinear orbits.
Master of Science
13
Cavin, Kaylyn, et Allan Forsman. « The Effects of Simulated Space Flight on Ovarian Tissue ». Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/115.
Texte intégralRésumé :
While many studies have shown harmful effects of space flight on many tissues and systems of the human body, few studies have been done on the effects of space flight on the reproductive system. While the microgravity conditions of space flight are common knowledge, there is another component of space flight, that being higher than ambient (on Earth) levels of radiation. The purpose of this study was to examine the effects of simulated space flight on follicular development in the ovaries of mice, and to determine which component of spaceflight, i.e. microgravity, radiation, or a combination of the two, might be responsible for any changes in this follicular development. To simulate the environment of space, mice were exposed to higher levels of radiation by the use of cobalt plates and to simulated microgravity using a technique known as hind limb unloading. Four groups of mice-were used in this study; a control or untreated group, a group exposed to higher levels of radiation, a group exposed to simulated microgravity, and a group treated in both high radiation and simulated microgravity. The mice were further subdivided within these groups based on the amount of time they were kept alive after treatment/exposure (one, four, and nine months). The ovarian tissues were then analyzed to see the effects of these simulated conditions on the development of follicles. In all three treatment groups, development of follicles was restricted compared to the control group. Follicles from the various treatment groups appeared to be in the early stages of their development. It should be noted that these are preliminary results as the study is still in progress. One of the overarching questions that has been put forth by NASA over the last few decades is, can an organism, in this case a mammalian organism, complete an entire life cycle in space? This study may help to answer some of that question. If any of the components of space flight proves to be harmful to the female reproductive tissues human colonization of space would be problematic. If the damage incurred during space flight is irreversible, colonization of other worlds would also be problematic.
14
Tsimpidas, Dimitrios. « Energetic O+ ions upstream from the Saturnian bow shock, measured by Cassini ». Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-220871.
Texte intégralRésumé :
We use particle and magnetic field data from the Ion and Neutral Camera (INCA) and the magnetometer (MAG) onboard Cassini to detect and examine an energetic particle event that occurred upstream from the Saturnian bow shock during DOY 229/2007. The energetic (>100 keV) O+ ions are observed only when the Interplanetary Magnetic Field (IMF) connects the spacecraft with the planetary bow shock. We provide strong evidence showing the magnetospheric origin of the observed ions: (1) We detect singly ionized oxygen (O+) which is not resident of the solar wind, (2) the particle pitch angle distribution indicates that the ions travel along the field line connecting the spacecraft to the bow shock and (3) the ion intensity increases are observed only during the periods of magnetic connection to the bow shock. Our results show that the Saturnian dayside magnetosphere is not as sealed as thought to be, but can -under certain circumstances- allow high energy magnetospheric plasma to leak into the nearby solar wind and further in space.
15
Aiken, Jo. « Space in Space : Privacy Needs for Long-Duration Spaceflight ». Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc799493/.
Texte intégralRésumé :
Space exploration is a uniquely human activity. As humans continue to push the limits of exploring the unknown, they have sought knowledge supporting the sustenance of life in outer space. New technologies, advancements in medicine, and rethinking what it means to be a “community” will need to emerge to support life among the stars. Crews traveling beyond the Moon will rely on the development of new technologies to support the technological aspects of their missions as well as their quality of life while away from Earth. Likewise, through advancements in medicine, scientists will need to address remaining questions regarding the effects of long-duration spaceflight on the human body and crew performance. Space explorers must learn to utilize these new technologies and medical advancements while learning to adapt to their new environment in space and as a space community. It is important that researchers address these issues so that human survival beyond Earth is not only achievable but so that life among the stars is worth living and sustaining. This thesis addressed these issues in an attempt to extend the trajectory of space exploration to new horizons.
16
Papanastasiou, Dimitris. « Space velocity correlation in orthogonal time-of-flight mass spectrometry ». Thesis, Manchester Metropolitan University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423073.
Texte intégral
17
Burkes, Darryl A. « GROUND SUPPORT FOR THE SPACE-BASED RANGE FLIGHT DEMONSTRATION 2 ». International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604565.
Texte intégralRésumé :
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe primary objective of the NASA Space-Based Range Demonstration and Certification program was to develop and demonstrate space-based range capabilities. The Flight Demonstration 2 flights at NASA Dryden Flight Research Center were conducted to support Range Safety (commanding and position reporting) and high-rate (5 Mbps) Range User (video and data) requirements. Required ground support infrastructure included a flight termination system computer, the ground-data distribution network to send range safety commands and receive range safety and range user telemetry data and video, and the ground processing systems at the Dryden Mission Control Center to process range safety and range user telemetry data and video.
18
Zambotti, Andrea. « Ground Testing and In-Flight Performance of a Space Mechanism ». Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/242871.
Texte intégralRésumé :
LISA Pathfinder is a mission designed for testing the key technologies of the future LISA mission, whose goal is the detection of gravitational waves through the measurement of the relative motion of dedicated proof masses.
In LISA Pathfinder, a critical task is the release of two Test Masses (TMs); each TM has to be injected into free fall by a dedicated Grabbing Positioning and Release Mechanism (GPRM). Despite the symmetrical design of the GPRM, during the release, as an effect of asymmetric impulses exchanged by the TM and the release tips of the GPRM, the TM can acquire a residual momentum. The release is successful if the residual momentum of the TM can be compensated by the force authority of the capacity control, which allows to centre the TM in its housing; as a consequence, a residual momentum of the TM higher than a maximum requirement can be critical for the mission.
In the nominal release configuration, which assumes a monodimensional dynamics of the mechanism along the axis of the release tips, the residual momentum can be produced by the asymmetry of pushing forces (due to relative time delays between the two tips) or by two unbalanced adhesive pulls on the two sides. In particular, the low repeatability of the adhesive pulls suggests their characterization through a dedicated on-ground experimental campaign.
The characterization of the adhesive pulls exchanged by the TM and the GPRM has been the focus of the on-ground experimental campaigns performed by the University of Trento since the early 2000s. The Transferred Momentum Measurement Facility (TMMF) has been developed: a mock-up of the TM release, which allows a high measurability of the adhesive pulls and guarantees the representativeness of the experiment, has been tested in order to estimate the properties of the adhesive force at the contact between the two bodies. The estimated parameters, applied to a model of the in-flight release, allowed to predict that the effect of the asymmetric adhesive pulls applied by the GPRM to the TM should not be critical for the residual momentum.
In this thesis we report the completion of the research on the effect of adhesion in the TM release of LISA Pathfinder, by means of additional on-ground experimental campaigns, and by comparing the predictions with the actual behaviour of the GPRM in the releases performed during the early stages of the LISA Pathfinder mission (2016).
Prior to the launch of the mission, the on-ground TMMF facility has been modified in 2015 in order to host a copy of the GPRM, thus increasing the representativeness of the experiment w.r.t. the nominal release. The on-ground test campaign, consisting in several release tests, allowed to obtain a new (conservative) estimation of the effect of adhesion in the TM release of LISA Pathfinder.
The estimation of the adhesive effect, which yielded first a conservative prediction, has been then improved by investigating in detail the release dynamics of the TMMF. Thanks to a vibration mode-based model of the TMMF, the effect of the adhesive pull on the measured dynamics has been estimated with its uncertainty, thus yielding a more precise prediction for the in-flight case.
The launch of the LISA Pathfinder mission occurred on December 3, 2015, and prior to the beginning of the scientific operations the two TMs have been injected into free fall. Due to the criticalities observed in the releases, an additional in-flight release test campaign has been planned during the end-of-life activities (June 2017), by alternating several times grab and release of each TM. The in-flight release campaign yielded a statistical distribution of the residual momentum of the TM at the release, which we analysed in detail in order to characterize the actual in-flight GPRM performance. In particular, we focused on the deviation of the predictions (based on the assumption of nominal release) w.r.t. the in-flight observations, by looking for the motivations of the residual momentum measured in the in-flight case.
19
Zambotti, Andrea. « Ground Testing and In-Flight Performance of a Space Mechanism ». Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/242871.
Texte intégralRésumé :
LISA Pathfinder is a mission designed for testing the key technologies of the future LISA mission, whose goal is the detection of gravitational waves through the measurement of the relative motion of dedicated proof masses.
In LISA Pathfinder, a critical task is the release of two Test Masses (TMs); each TM has to be injected into free fall by a dedicated Grabbing Positioning and Release Mechanism (GPRM). Despite the symmetrical design of the GPRM, during the release, as an effect of asymmetric impulses exchanged by the TM and the release tips of the GPRM, the TM can acquire a residual momentum. The release is successful if the residual momentum of the TM can be compensated by the force authority of the capacity control, which allows to centre the TM in its housing; as a consequence, a residual momentum of the TM higher than a maximum requirement can be critical for the mission.
In the nominal release configuration, which assumes a monodimensional dynamics of the mechanism along the axis of the release tips, the residual momentum can be produced by the asymmetry of pushing forces (due to relative time delays between the two tips) or by two unbalanced adhesive pulls on the two sides. In particular, the low repeatability of the adhesive pulls suggests their characterization through a dedicated on-ground experimental campaign.
The characterization of the adhesive pulls exchanged by the TM and the GPRM has been the focus of the on-ground experimental campaigns performed by the University of Trento since the early 2000s. The Transferred Momentum Measurement Facility (TMMF) has been developed: a mock-up of the TM release, which allows a high measurability of the adhesive pulls and guarantees the representativeness of the experiment, has been tested in order to estimate the properties of the adhesive force at the contact between the two bodies. The estimated parameters, applied to a model of the in-flight release, allowed to predict that the effect of the asymmetric adhesive pulls applied by the GPRM to the TM should not be critical for the residual momentum.
In this thesis we report the completion of the research on the effect of adhesion in the TM release of LISA Pathfinder, by means of additional on-ground experimental campaigns, and by comparing the predictions with the actual behaviour of the GPRM in the releases performed during the early stages of the LISA Pathfinder mission (2016).
Prior to the launch of the mission, the on-ground TMMF facility has been modified in 2015 in order to host a copy of the GPRM, thus increasing the representativeness of the experiment w.r.t. the nominal release. The on-ground test campaign, consisting in several release tests, allowed to obtain a new (conservative) estimation of the effect of adhesion in the TM release of LISA Pathfinder.
The estimation of the adhesive effect, which yielded first a conservative prediction, has been then improved by investigating in detail the release dynamics of the TMMF. Thanks to a vibration mode-based model of the TMMF, the effect of the adhesive pull on the measured dynamics has been estimated with its uncertainty, thus yielding a more precise prediction for the in-flight case.
The launch of the LISA Pathfinder mission occurred on December 3, 2015, and prior to the beginning of the scientific operations the two TMs have been injected into free fall. Due to the criticalities observed in the releases, an additional in-flight release test campaign has been planned during the end-of-life activities (June 2017), by alternating several times grab and release of each TM. The in-flight release campaign yielded a statistical distribution of the residual momentum of the TM at the release, which we analysed in detail in order to characterize the actual in-flight GPRM performance. In particular, we focused on the deviation of the predictions (based on the assumption of nominal release) w.r.t. the in-flight observations, by looking for the motivations of the residual momentum measured in the in-flight case.
20
Bevacqua, Timothy R. « Advanced Flight Control Issues for Reusable Launch Vehicles ». Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1097601560.
Texte intégral
21
Aintablian, Haig. « Space Medicine : A Historical Look into Medical Problems in Space and the Implications they have on the Mars Missions ». The University of Arizona, 2018. http://hdl.handle.net/10150/626579.
Texte intégral
22
Vasudevan, Gopal. « A homotopy approach to the solutions of minimum-fuel space-flight rendezvous problems ». Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54442.
Texte intégralRésumé :
A homotopy approach for solving constrained parameter optimization problems is examined. The first order necessary conditions, with the complementarity conditions represented using a technique due to Mangasarian, are solved. The equations are augmented to avoid singularities which occur when the active constraint set changes. The Chow-Yorke algorithm is used to track the homotopy path leading to the solution to the desired problem at the terminal point.
Since the Chow-Yorke algorithm requires a fairly accurate computation of the Jacobian matrix, analytical representation of the system of equations is desired. Consequently, equations obtained using the true anomaly regularization of the governing equations were employed for the above purpose. A homotopy map suited for the space-flight rendezvous problem including a minimum radius constraint is developed, which can naturally deform any initial problem into some other valid desired problem. Several coplanar and non-coplanar solutions for circular and elliptic cases have been presented for the restricted time problem with a minimum radius constraint.Ph. D.
23
Enright, John Patrick 1974. « A flight software development and simulation framework for advanced space systems ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29911.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.Includes bibliographical references (p. 293-302).
Distributed terrestrial computer systems employ middleware software to provide communications abstractions and reduce software interface complexity. Embedded applications are adopting the same approaches, but must make provisions to ensure that hard real-time temporal performance can be maintained. This thesis presents the development and validation of a middleware system tailored to spacecraft flight software development. Our middleware runs on the Generalized Flight Operations Processing Simulator (GFLOPS) and is called the GFLOPS Rapid Real-time Development Environment (GRRDE). GRRDE provides publish-subscribe communication services between software components. These services help to reduce the complexity of managing software interfaces. The hard real-time performance of these services has been verified with General Timed Automata modelling and extensive run-time testing. Several example applications illustrate the use of GRRDE to support advanced flight software development. Two technology-focused studies examine automatic code generation and autonomous fault protection within the GRRDE framework. A complex simulation of the TechSat 21 distributed spacebased radar mission highlights the utility of the approach for large-scale applications.
by John Patrick Enright.
Ph.D.
24
Singh, Mukul Kumar. « Evaluating levy flight parameters for random searches in a 2D space ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83632.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pag 23).
It is experimentally known that the flight lengths of random searches by foragers such as honey bees statistically belong to a power law distribution. Optimality of such random searches has been a topic of extensive research because knowing their optimal parameters may help applied sciences. Viswanathan et al. have shown the inverse-square power law to be the optimal law for such random searches. This thesis explores the capability of the model presented in such that it can be applied to Unmanned Autonomous Vehicles (UAVs). The thesis also identifies the minimum flight length, lmin, as an important factor that needs to be controlled based on the UAV's sensor range. We present a theoretical lmin as an explicit function of the sensor range, rv, and an estimated target density, p.
by Mukul Kumar Singh.
S.B.
25
Ab, Wahid Mastura. « Flight guidance along 3D+T trajectories and space indexed traffic management ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30196/document.
Texte intégralRésumé :
Avec la forte augmentation actuelle et future du trafic aérien, les questions relatives à la capacité, la sécurité et les effets environnementaux du transport aérien vont se poser de façon chaque fois plus critique. L'objectif général de cette thèse est de contribuer à l'amélioration de l'opération et de l'organisation du trafic aérien dans cette perspective de croissance. Le premier objectif spécifique de cette thèse est de faire la synthèse d'une loi de commande permettant aux avions de transport de suivre avec précision une trajectoire 3D+T. Le deuxième objectif spécifique de cette thèse est d'introduire une organisation particulière des corridors aériens, les airstreams, compatible avec la loi de guidage développée et permettant d'utiliser au mieux la capacité du corridor. Ainsi dans une première étape est introduite la dynamique de guidage des avions de transport, ainsi que les systèmes de guidage et de gestion du vol des avions modernes. Ensuite les principaux éléments de l'organisation de la gestion et du contrôle du trafic aérien sont introduits. La loi de guidage 3D+T est développée, simulée et ses performances sont analysées. L'étude d'une manœuvré de changement de voie dans un airstream est alors menée et mise en œuvre dans le cadre de la gestion du trafic à l'intérieur de celui-ci. Finalement les conclusions et perspectives de cette étude sont présentéesWith the increase in air traffic, surely a question of flight efficiency (delays), environment impact and safety arise. This calls for improvements in accuracy of spatial and temporal trajectory tracking. The first main objective of this thesis is to contribute to the synthesis of a space-indexed nonlinear guidance control law for transportation aircraft presenting enhanced tracking performances and to explore the performances and feasibility of a flight guidance control law which is developed based on a space-indexed reference to track a 3D+T reference trajectory using nonlinear dynamic inversion control. The proposed guidance control law present reduced tracking errors and able to meet more easily overfly time constraints. Before presenting the main approaches for the design of the 3D+T guidance control laws; the modern flight guidance and flight dynamics of transportation aircraft, including explicitly wind components are first introduced. Then, a description of the current and modern air traffic organization including the organization of air traffic in high density flow will be shown and this will lead to a description of the Airstreams concept. This proposed concept is to organize main traffic flows in congested airspace along airstreams which are characterized by a three dimensional (3D) common reference track (ASRT). Finally, a scenario to perform basic maneuvers inside the airstream following a 3D+T trajectory using a common space-indexed will be developed and will be used to illustrate the traffic management along an airstream
26
Vignotto, Davide. « Analysis of the in-Flight Performance of a Critical Space Mechanism ». Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/323575.
Texte intégralRésumé :
Gravitational waves detection is a challenging scientific objective, faced by scientist in the last 100 years, when Einstein theorized their existence. Despite multiple attempts, it was only in 2016 that the first observation of a gravitational wave was officially announced. The observation, worth a Nobel Prize, was made possible thanks to a worldwide collaboration of three large ground-based detectors. When detecting gravitational waves from ground, the noisy environment limits the frequency bandwidth of the measurement. Thus, the type of cosmic events that are observable is also limited. For this reason, scientists are developing the first gravitational waves detector based in space, which is a much quieter environment, especially in the sub-Hertz bandwidth. The space-based detector is named laser interferometer space antenna (LISA) and its launch is planned for 2034. Due to the extreme complexity of the mission, involving several new technologies, a demonstrator of LISA was launched and operated between 2015 and 2017. The demonstrator mission, called LISA Pathfinder (LPF), had the objective to show the feasibility of the gravitational waves observation directly from space, by characterizing the noise affecting the relative acceleration of two free falling bodies in the milli-Hertz bandwidth. The mission was a success, proving the expected noise level is well below the minimum requirement.
The free-falling bodies of LPF, called test masses (TMs), were hosted inside dedicated electrode housings (EH), located approximately 30 cm apart inside the spacecraft. When free falling, each TM stays approximately in the center of the EH, thus having milli-meter wide gaps within the housing walls. Due to the presence of such large gaps, the TMs were mechanically constrained by dedicated mechanisms (named CVM and GPRM) in order to avoid damaging the payload during the launch phase and were released into free fall once the spacecraft was in orbit. Prior to the start of the science phase, the injection procedure of the TMs into free-fall was started. Such a procedure brought each TM from being mechanically constrained to a state where it was electro-statically controlled in the center of the EH. Surprisingly, the mechanical separation of the release mechanism from the TM caused unexpected residual velocities, which were not controllable by the electrostatic control force responsible for capturing the TM once released. Therefore, both the TMs collided with either the surrounding housing walls or the release mechanism end effectors. It was possible to start the science phase by manually controlling the release mechanism adopting non-nominal injection strategies, which should not be applicable in LISA, due to the larger time lag. So, since any release mechanism malfunctioning may preclude the initialization of LISA science phase, the GPRM was extensively tested at the end of LPF, by means of a dedicated campaign of releases, involving several modifications to the nominal injection procedure. The data of the extended campaign are analyzed in this work and the main conclusion is that no optimal automated release strategy is found for the GPRM flight model as-built configuration that works reliably for both the TMs producing a nominal injection procedure. The analysis of the in-flight data is difficult since the gravitational referencesensor of LPF is not designed for such type of analysis. In particular, the low sampling frequency (i.e., 10 Hz) constitutes a limiting factor when detecting instantaneous events such as collisions of the TM. Despite the difficulties of extracting useful information on the TM residual velocity from the in-flight data, it is found that the main cause of the uncontrollable state of the released TM is the collision of the TM with the plunger, i.e., one of the end-effectors of the GPRM. It is shown that the impact is caused by the oscillation of the plunger or by the elastic relaxation of the initial preload force that holds the TM. At the end of the analysis, some improvements to the design of the release mechanism are brie y discussed, aimed at maximizing the probability of performing a successful injection procedure for the six TMs that will be used as sensing bodies in the LISA experiment.
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Goodson, Troy D. « Fuel-optimal control and guidance for low-and medium-thrust orbit transfer ». Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/12900.
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Olsen, Carrie Dumas. « Characterization of the relative motion of rendezvous between vehicles in proximate, highly elliptic orbits / ». Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008410.
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Mineiro, Michael C. « Commercial human space flight in the United States : federal licensing and tort liability ». Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111580.
Texte intégralRésumé :
In the early 21st century, the private commercial space transportation industry demonstrated that commercial human space flight is both technologically and economically feasible. In 2004, the United States Congress responded by passing legislation authorizing the Department of Transportation to license and regulates commercial human space flight.This thesis examines and assesses the U.S. commercial human space flight vehicle licensing and regulatory law. Tort liability is inextricably linked to the success of the commercial human space flight industry and to that end this thesis provides an analysis of U.S. tort liability law in the event of a commercial human space flight vehicle accident.
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Gao, Yang. « Advances in low-thrust trajectory optimization and flight mechanics / ». free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3115547.
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Johnson, Eric N. « Limited authority adaptive flight control ». Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/12953.
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Youssef, Hazim S. « Laser engine simulation using pressure based navier-stokes solver ». Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10052007-143624/.
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Bruner, William W. « National Security Implications of Inexpensive Space Access ». Maxwell AFB, Ala. : Air University Research Coordinator Office, 1998. http://www.au.af.mil/au/database/research/ay1995/saas/brunerww.htm.
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Martell, Craig Alan. « Parameter optimization of atmospheric skip trajectories for use in minimum fuel usage transfer orbits ». Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41686.
Texte intégralRésumé :
The problem of developing a generalized impulse as a function of a set of parameters is investigated. The proposed generalized impulse alters an existing orbit by producing, over some period of time, a change in velocity, ΔV, as well as a change in position, Δr. The generalized impulse is described by parameters associated with an instantaneous change in velocity as well as parameters associated with an atmospheric skip trajectory. Closed form solutions are obtained through several changes of independent variable, the use of modified Chapman variables and the consequent analytical integration of the uncoupled equations. The closed form solutions contain between two and six parameters depending on the complexity of the desired skip trajectory. Fuel optimal transfer orbits are obtained using the generalized impulse along with Keplerian arcs and instantaneous changes in velocity. Families of coplanar and noncoplanar transfers for circular orbit to circular orbit are numerically generated. The generated transfer trajectories involve the rendezvous of two vehicles. The orbits are not globally optimal but rather optimal for the specified number and type of velocity impulses specified. The optimal solution to the nonlinear problem is determined via sequential quadratic programming which satisfies the Kuhn-Tucker optimality conditions for constrained minimization. It is found that for transfer between coplanar and noncoplanar orbits, solutions using the generalized impulse compare favorably with solutions obtained by optimal control theory. Numerical solution to complex problems involving transfer from general orbit to general orbit were not obtained.Master of Science
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Rehwald, Stephen Paul Tyler Carolyn Louise. « Analysis of the first successful flight of GPS aboard the space shuttle / ». Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA280993.
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Sund, Erik. « Flight Analysis of a Suborbital Space Probe : the Light Airbag-Protected Lander ». Thesis, KTH, Rymd- och plasmafysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92526.
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A novel Inatable Aerodynamic Decelerator (IAD) and platform for multi-pointmeasurements in the ionosphere, has been evaluated in the REXUS (Rocket-bourneEXperiments for University Students) program. The experiment, named LAPLander(Light Airbag-Protected Lander), was launched from Esrange 4th of March 2010 to analtitude of 88 km. LAPLander is a 3.043 kg right-circular cylinder with a diameter of24 cm and a length of 8.4 cm when the IAD is folded inside. At ejection LAPLanderis spin stabilized around its polar axis with 3.5-4 Hz. Contact was lost after ejectionwhich points to an electrical failure.This thesis presents an evaluation of the LAPLander IAD and a 6 Degrees-Of-Freedom (6-DOF) ight analysis. The 6-DOF simulation indicates that LAPLanderwould start to wobble, but if the rotation around its polar axis is decreased morethan estimated, it will start to autorotate. Perhaps with high enough angular rate todemand special precautions if a parachute is to be used as a mean of recovery. TheLAPLander IAD is designed to deploy at 6 km altitude. If the IAD was inated inspace instead, the resulting reduction in the ballistic factor at reentry would save masson the heat protection system, and thus save mass on the overall recovery system. AnIAD derived from the LAPLander IAD capable of a 250 km apogee reentry will beprovided.The IAD incorporate CO2 cartridges to inate the system, these do each containa CO2 valve. A pre-launch valve failure resulted in that LAPLander ew without aworking IAD. The valves are based on the principle that resistors heat Field's metalabove 62C (the melting temperature). The main mechanism of the valve failure seemsto be brittle creep in the Field's metal at this point. Some IAD ination-problematicshave been detected and this report provides a few recommendations.
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Rehwald, Stephen Paul, et Carolyn Louise Tyler. « Analysis of the first successful flight of GPS aboard the space shuttle ». Thesis, Monterey, California. Naval Postgraduate School, 1994. http://hdl.handle.net/10945/27959.
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Approved for public release; distribution unlimited.A Trimble Advanced Navigation Sensor (TANS) Quadrex Global Positioning System (GPS) receiver processing unit and three antenna/preamplifier assemblies were flown aboard Space Shuttle Discovery, STS-51, as part of DTO 700-6, GPS On-orbit Demonstration (GOOD). The experiment was designed to quantify advantages and identify potential problem areas for Space Shuttle GPS operations using a low cost, commercial, space configured, GPS receiver. GPS data, including position, velocity, time, health, and status information were recorded during the mission. Following the mission, a reference trajectory was generated by NASA Johnson Space Center through post-processing of the Orbiter's on board navigation state. The recorded GPS data has been analyzed and compared to the reference trajectory to evaluate the navigational performance of the receiver. Additionally, postflight filtering of the GPS data has been performed in order to determine whether a significant increase in performance may be obtained through filtering
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McCarthy, Bryan Patrick. « Flight hardware development for a space-based robotic assembly and servicing testbed ». Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90780.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.Cataloged from PDF version of thesis. "This material is declared a work of the United States Government and is not subject to copyright protection in the United States."
Includes bibliographical references (pages 161-165).
Robotic assembly and servicing missions in space are becoming increasingly attractive for their potential to expand space capabilities and save money. Future missions may construct large systems on-orbit, service existing space assets, or remove retired satellites from valuable locations in the Geosynchronous orbit, among other things. Due to the high-risk nature of these missions, rigorous test facilities are a necessity. This thesis examines the existing testbeds for robotic assembly and servicing technologies and argues that a new, space-based testbed is necessary. It presents initial ground testing results for applicable control concepts, which also indicate that the dynamic authenticity associated with a six-degree-of-freedom on-orbit testbed is crucial for further development. This thesis then presents the requirements for such a testbed and describes the SPHERES Facility on the International Space Station. The facility, created by members of MIT's Space Systems Laboratory, has many of the desired testbed characteristics and can be easily expanded to meet the requirements through a hardware augmentation known as the Halo. The thesis develops the requirements for the Halo and then steps through the conception, design, and implementation of that hardware, along with the planned operations aboard the International Space Station.
by Bryan Patrick McCarthy.
S.M.
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Lawton, John Arthur. « Fuel-optimal space-flight transfer solutions through a redundant adjoint variable transformation ». Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/29273.
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A transformation between minimum dimension adjoint variables and redundant adjoint variables is derived in this dissertation. The transformation is then applied between the adjoint variables associated with Cartesian position and velocity vectors and a set of redundant adjoint variables associated with certain regularized variables (Schumacher variables). This transformation proves to be very beneficial when it is applied to minimum-fuel space rendezvous and intercept problems. It facilitates using attributes from the two systems simultaneously; a new necessary condition in Schumacher adjoints is derived in this dissertation, and this together with classical necessary conditions for fuel-optimal transfer (existing in the position and velocity space) leads to a numerical algorithm which seems to be quite robust in finding candidate optimal control solutions for space transfer problems.Ph. D.
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Brown, K. D., et Trevor Sorensen. « HIGH ALTITUDE TRANSMITTER FLIGHT TESTING ». International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605062.
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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaThis paper describes a high altitude experimental flight test platform developed by the University of Kansas (KU) and the National Nuclear Security Administration’s Kansas City Plant (NNSA’s Kansas City Plant) for high altitude payload flight testing. This platform is called the Kansas University Balloon Experiment Satellite (KUBESat). The paper describes the flight test platform and experimental flight test results captured at Fort Riley, KS from characterization of the KCP developed Distributed Transmitter (DTX).
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Walter, Patrick L. « OPTIMIZING FLIGHT SHOCK AND VIBRATION MEASUREMENT BY RF LINKS ». International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609222.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaAcquiring shock and vibration data from flight vehicles through rf telemetry links has numerous associated challenges. Yet, these measurements are important to establish environmental specifications to provide a basis for system or component design and testing. The principal limitation in acquiring these measurements is the frequency bandwidth available for data transmission. This limited bandwidth is often responsible for invalid data being accepted as valid. This work provides a brief review of time and frequency division multiplexing to identify the potential error contributors to shock and vibration measurements. Its focus is on the design of acceleration measurement systems to eliminate these errors and optimize individual measurement channel performance.
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Tolbert, Douglas Robert. « Spacecraft formation flight at sun-earth/moon libration points ». Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Tolbert_09007dcc8069e8b8.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 14, 2009) Includes bibliographical references (p. 68-71).
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Brewster, Richard Wyatt. « Systems analysis of an ion-propelled orbital transfer vehicle ». Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-12302008-063634/.
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Villlalba, Corbacho Víctor Manuel. « Vibro-acoustic monitoring for in-flight spacecraft ». Thesis, Luleå tekniska universitet, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-66104.
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The concept of using the vibration transmitted through the structure of space systems whilst they are in flight for monitoring purposes is proposed and analysed.The performed patent review seems to indicate that this technique is not currently used despite being, in principle, a good way to obtain valuable knowledge about the spacecraft’s condition. Potential sources of vibration were listed and some of them were down-selected via a trade-off analysis for implementation in a numerical model of a CubeSat structure. Models were proposed for the sources chosen and implemented in the Ansys Workbench software, along with a simplified structure designed to be representative of a generic picosatellite mission.The results confirmed very different amplitude and frequency ranges for the sources of interest, which would make it difficult to monitor them with one type of sensor.Basic system requirements for accelerometer operating under space conditions were derived and commercial sources were identified as already having the technologies needed.The conclusion was a positive evaluation of the overall concept, although revising negatively the initial expectations for its performance due to the diversity encountered in the sources.
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Yazdi, Kian. « Conceptual design and flight simulation of space station missions beyond low earth orbit ». [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29036.
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Vetrisano, Massimo. « Uncertainty quantification and state estimation for complex nonlinear problems in space flight mechanics ». Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28435.
Texte intégralRésumé :
The complex dynamics which describe the motion of a spacecraft far from a massive planetary body or in a highly perturbed environment close to minor celestial objects raises two fundamental but related problems. The first is represented by the difficulty to accurately predict the evolution of its orbit even over short period when its initial conditions are known with a small degree of confidence. The second is given by the need for precise real time estimation of the trajectory when the spacecraft orbits near the asteroid’s surface to avoid impacting on it. The main example of the first problem is the perturbed four body problem for the Earth-Sun-Moon system. Earth-Sun Lagrangian Point Orbits (LPOs) are often selected for astrophysics and solar terrestrial missions while low cost missions aim at exploiting the so called Weak Stability Boundaries (WSB) to move at low propellant expense within the Earth sphere of influence. As current and future missions are planned to be placed on LPOs, it is a critical aspect to clear these regions at the end of operations to avoid damages to other spacecraft. For the second problem, we have a great number of asteroids and comets orbiting the inner solar system; they represent the so-called minor celestial objects which are very interesting for science since they preserve the remnants of the early formation of the planets and could shed light on the origins of life. At the same time they are very appealing for future commercial applications for the high content of precious ore. Among these celestial objects, the family of Near Earth Objects (NEOs) follows trajectories which lie close to, and sometimes cross, the Earth’s orbit. The impact hazard with the Earth has started to become considered as serious threat. Over the last three decades a number of missions have flown to and explored asteroids and comets, relying heavily on ground support with limited autonomy. In order to perform either asteroid’s exploration or collision hazard protection, autonomous navigation is needed, also to deal with the uncertain environment. Then the manipulation of asteroids’ orbit and attitude for deflection purposes is therefore required and an interesting problem to be studied. The aim of the research presented in this dissertation is to identify and develop methodologies for uncertainty propagation for spacecraft orbit and the application to orbit determination for complex nonlinear space mechanics problems, with particular care paid to the case of close proximity operations which are required when performing missions to minor celestial objects. The results are not limited only to this kind of problem but can be applied also to different scenarios. A first set of results focuses on the prediction of the trajectory evolution under initial condition uncertainties. The accuracy of the propagation of uncertainties is intimately related to the process of trajectory estimation, which relies on the use of the covariance matrix. The covariance matrix gives an idea of the dispersion of the spacecraft in terms of position and velocity. Different techniques to propagate the covariance matrix are used to predict the evolution of the trajectory when the initial conditions are known only to a certain degree of accuracy. They are compared under a highly nonlinear scenario where a spacecraft is injected into a disposal orbit towards an impacting trajectory with the Moon from a Lagrangian Point Orbit. A second set of results focuses on the identification of the estimation techniques applied to a single spacecraft. The estimation process performs well depending on the capability to propagate the covariance matrix and to incorporate the new information. A number of filtering techniques based on the Kalman and H∞ filters, employing different methods to handle the propagation of the covariance matrix, are presented and tested in typical nonlinear environments, i.e. a WSB transferan asteroid proximity, to draw precious information on their performance. The analyses demonstrate that only a hybrid Kalman- H∞ filter can enable the spacecraft to estimate its trajectory with a good balance between accuracy and computational costs. Then this method is applied to the navigation of spacecraft formation about a NEO showing that the navigation performance is significantly improved by sharing relative information among the spacecraft and the overall system is shown to be fault-tolerant. Finally the orbit’s and attitude manipulation of a small asteroid using a laser ablation system is analysed. An on-board state estimation and control algorithm is presented that simultaneously provides an optimal proximity control and control of the rotational motion of the asteroid. During the deflection, the proximity motion of the spacecraft is coupled with the orbital and rotational motion of the asteroid. The combination of the deflection acceleration, solar radiation pressure, and gravity field and plume impingement will force the spacecraft to drift away from the asteroid. In turn, a variation of the motion of the spacecraft produces a change in the modulus and direction of the deflection action which modifies the rotational and orbital motion of the asteroid.
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Winter, Tyler Forrest. « Analysis of access-to-space missions utilizing on-board energy management and entropic analysis ». Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Winter_09007dcc804d07b4.pdf.
Texte intégralRésumé :
Thesis (M.S.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 18, 2008) Includes bibliographical references (p. 127-129).
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Ewig, Ralph. « Identification of a physically idealized human rated rocket based interplanetary transportation system / ». Thesis, Connect to this title online ; UW restricted, 2006. http://hdl.handle.net/1773/9974.
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Forshaw, Jason Leigh. « Transitioning flight guidance and control for a twin rotor tailsitter unmanned air vehicle ». Thesis, University of Surrey, 2013. http://epubs.surrey.ac.uk/837960/.
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The future of aircraft lies in highly intelligent vehicles which are able to adapt themselves to different missions and take-off and land anywhere. Tailsitters, aircraft capable of controlled transitions between horizontal flight (like a fixed-wing aircraft) and vertical flight (like a rotary-wing aircraft), are one such form of vehicle. The focus of this research stems from a collaboration between the Surrey Space Centre and QinetiQ involving a new class of VTOL tailsitter - the QinetiQ Eye-On™ UAV - which offers uniqueness from all other known tailsitters in its use of twin helicopter rotors, elevons and a rudderless flying-wing design. A core objective of this research is to develop a control and navigation architecture capa.ble of handling the transitional flight regime in tailsitters and to understand the mechanism by which a transition can be controlled. Very little past research has addressed either of these in detail, often including only cursory modelling and simulation, no regard to how transitions can be 'shaped', and with no consideration of optimisation of transitions or whether their control laws are even robust. Another shortcoming of past literature is the minimal amount of experimental work undertaken which mostly uses only generic, simple single-propeller aircraft and does not consider transitional flight. Furthermore, examination of real-world applications where a tailsitter can be used has also been barely considered in literature. The limitations are addressed in three research divisions: I, II, III. {I} Development of a novel six degree of freedom (6-DOF) non-linear model with custom-designed numerical fluid dynamics, has allowed. high-fidelity simulation of all flight regimes to be performed. The developed control and navigation architecture is the first all-encompassing control architecture for the class of twin rotor tailsitters; it uses rudimentary low-level controllers and is capable of performing three different transitions: vertical to horizontal (V to H) , H to V (altitude elevation) and H to V (altitude invariant). The last of these is a ground-breaking discovery; transitions from H to V can be performed with virtually no increase in altitude. One improvement from past literature is that transitioning is undertaken in a closed-loop manner by commanding the vehicle to follow velocity and pitch setpoints. A carefully selected set of parameters has been devised to allow transitions to be shaped by transition time period, flight speed, sample size and smoothness of the control setpoint command. For the first time optimisation is applied to obtain ideal parameters for the transitions and robustness simulations stochastically consider environmental disturbances and variation of vehicle mass. [II] A comprehensive experimental framework has been developed tha.t uses various advanced testbed configurations to validate the control architecture, requiring the fusion of both aeroplane and helicopter technologies. Initially, an indoor motion capture testbed uses a series of precursory vehicles (including both quadrotor and Chinook) to pioneer taiisitter technology. A thrust testbed was also developed to explore thrust curve relationships and obtain optimal thrust zones for differing flight regimes. The outdoor testbed required the development of a complete self-contained autopilot system, including telemetry and ground station, which was tested in a progressive fl ight campaign spanning four flight locations across the UK. The experimentation forms the first demonstration of &-DOF untethered flight for the class of twin rotor tailsitters in VTOL, manual transitional and semi-autonomous transitiona.l modes. [III] In terms of systems analysis, two distinct civil and military scenarios are evaluated: linear asset monitoring, and perch and stare (which includes an innovative miniaturisation analysis) . The first thorough and realistic consideration is also given to the use of a reusable tailsitter v.'ith a docking station for staged exploration in extra-terrestrial environments. Industrially, the research programme extensively develops the technology necessary for autonomous flight of the UAV and extends from Technology Readiness Level (TRL) 2 to 6. Academically, significant contributions have been made to the field including: tailsitter modelling, transitioning methodology, control architecture, optimisation, testbed design, flight experimentation, systems design.
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Yu, Alvin. « Multi-mode exercise device| A gravity independent integrated countermeasure for long term space flight ». Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1523076.
Texte intégralRésumé :
The purpose of this study was to examine the efficacy of a gravity independent multi-mode exercise device (M-MED) and to evaluate a resistance (RE) and aerobic (AE) exercise protocol. Thirty-two participants (16 females and 16 males) aged 22 ± 0.4 years completed 5 weeks of training: RE, 4 sets of7 repetitions of squats 2 days a week and AE consisting of four, 4 minute high-intensity interval rowing at ∼90% V˙O2max, 3 days per week. Three repetition maximum (3RM) leg press increased in both AE+RE and RE groups by +20% and ∼30% respectively. AE+RE V02max increased by 7.73 ± 1.99%. Cross sectional Area ofthe quadriceps femoris increased by 8.73 ± 3.94% in AE+RE and 16.5 ± 5.5% in RE. Isokinetic improvements were seen at all speeds in both groups. Aerobic capacity and strength gains indicate that the M-MED is effective in providing robust stimuli to musculoskeletal and cardiovascular systems.