2,866 research outputs found
The Trojan Epic Posthomerica
No full textBrilliantly revitalized by James, the Trojan Epic will appeal to a wide range of readers interested in Greek mythology and the legend of Troy.Intro -- Contents -- Preface -- Introduction -- 1 Penthesileia -- 2 Memnon -- 3 The Death of Achilles -- 4 The Funeral Games of Achilles -- 5 The Contest for the Armor of Achilles -- 6 The Arrival of Eurypylos -- 7 The Arrival of Neoptolemos -- 8 The Death of Eurypylos -- 9 The Arrival of Philoktetes -- 10 The Death of Paris -- 11 The Defense of Troy -- 12 The Wooden Horse -- 13 The Sack of Troy -- 14 The Departure of the Greeks -- Critical Summary -- Commentary -- Index of Names -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- R -- S -- T -- V -- W -- X -- ZBrilliantly revitalized by James, the Trojan Epic will appeal to a wide range of readers interested in Greek mythology and the legend of Troy.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
2008 LC18: A potentially unstable Neptune Trojan
No full textThe recent discovery of the first Neptune Trojan at the planet's trailing (L5) Lagrange point, 2008 LC18, offers an opportunity to confirm the formation mechanism of a member of this important tracer population for the Solar system's dynamical history. We tested the stability of 2008 LC18's orbit through a detailed dynamical study, using test particles spread across the ±3σ range of orbital uncertainties in a,e,i and Ω. This showed that the wide uncertainties of the published orbit span regions of both extreme dynamical instability, with lifetimes 1Gyr. The stability of 2008 LC18's clones is greatly dependent on their semimajor axis and only weakly correlated with their orbital eccentricity. Test particles on orbits with an initial semimajor axis of less than 29.91au have dynamical half-lives shorter than 100Myr; in contrast, particles with an initial semimajor axis of greater than 29.91au exhibit such strong dynamical stability that almost all are retained over the 1Gyr of our simulations. More observations of this object are necessary to improve the orbit. If 2008 LC18 is in the unstable region, then our simulations imply that it is either a temporary Trojan capture or a representative of a slowly decaying Trojan population (like its sibling the L4 Neptunian Trojan 2001 QR322), and that it may not be primordial. Alternatively, if the orbit falls into the larger, stable region, then 2008 LC18 is a primordial member of the highly stable and highly inclined component of the Neptune Trojan population, joining 2005 TN53 and 2007 VL305. We attempted to recover 2008 LC18 using the 2.3-m telescope at Siding Spring Observatory to provide this astrometry, but were unsuccessful due to the high stellar density of its current sky location near the Galactic centre. The recovery of this object will require a telescope in the 8-m class
Review of machine learning based hardware Trojan detection methods
No full textAs integrated circuit (IC) design gets more complicated, outsourcing parts of the IC design and fabrication is commonly applied to simplify the production and reduce the cost. This leads to the threat of malicious manipulation to the design by the third parties involved. Such threat is considered as hardware Trojan attack, which could pose adverse impacts to a system or network. Recently, hardware Trojan is gaining more interest as a research subject, especially pre-silicon detection. Various kinds of hardware Trojan detection approaches have been proposed to detect different Trojan types in different circuits. This study summarises the existing hardware Trojan detection methods and discusses the attributes of the methods to better distinguish them between each other. Existing presilicon detection methods are reviewed, which includes verification-based, threshold-based and machine learning-based feature analysis techniques. The objective of this study is to ease the future hardware-Trojan-related research by providing an organised summary of detection techniques, especially pre-silicon detection
2001 QR322: a dynamically unstable Neptune Trojan?
No full textSince early work on the stability of the first Neptunian Trojan, 2001 QR322, suggested that it was a dynamically stable, primordial body, it has been assumed that this applies to both that object and its more recently discovered brethren. However, it seems that things are no longer so clear-cut. In this work, we present the results of detailed dynamical simulations of the orbital behaviour of 2001 QR322. Using an ephemeris for the object that has significantly improved since earlier works, we follow the evolution of 19 683 test particles, placed on orbits within the observational error ellipse of 2001 QR322's orbit, for a period of 1 Gyr. We find that majority of these 'clones' of 2001 QR322 are dynamically unstable, exhibiting a near-exponential decay from both the Neptunian Trojan cloud (decay half-life of ∼550 Myr) and the Solar system (decay half-life of ∼590 Myr). The stability of the object within Neptune's Trojan cloud is found to be strongly dependent on the initial semimajor axis used, with these objects located at a≥ 30.30 au being significantly less stable than those interior to this value, as a result of their having initial libration amplitudes very close to a critical threshold dividing regular and irregular motion, located at ∼70°–75° (full extent of angular motion). This result suggests that if 2001 QR322 is a primordial Neptunian Trojan, it must be a representative of a population that was once significantly larger than that we see today and adds weight to the idea that the Neptune Trojans may represent a significant source of objects moving on unstable orbits between the giant planets (the Centaurs)
Lithium and boron burning S(E)-factor measurements at astrophysical energies via the Trojan Horse method
No full textThe residual amount of light elements lithium, beryllium and boron (LiBeB) abundances in stellar atmospheres has been largely accepted as one of the most powerful probes for understanding stellar structure and mixing phenomena. They are in fact gradually destroyed at different depths of stellar interior mainly by (p,α), thus their fate in stars is an incomparable tool for studying mixing processes. In order to avoid extrapolation procedures on the available direct S(E)-factor measurements, the Trojan Horse Method (THM) has been developed, allowing one to measure the bare nucleus S(E)-factor for astrophysically relevant reactions without experiencing Coulomb penetrability effects. Here, a summary on the recent 6,7Li and 11B TH investigations will be given and the corresponding results discussed
The capture of Trojan asteroids by the giant planets during planetary migration
No full textOf the four giant planets in the Solar system, only Jupiter and Neptune are currently known to possess swarms of Trojan asteroids – small objects that experience a 1:1 mean motion resonance with their host planet. In Lykawka et al., we performed extensive dynamical simulations, including planetary migration, to investigate the origin of the Neptunian Trojan population. Utilizing the vast amount of simulation data obtained for that work, together with fresh results from new simulations, we here investigate the dynamical capture of Trojans by all four giant planets from a primordial trans-Neptunian disc. We find the likelihood of a given planetesimal from this region being captured on to an orbit within Jupiter's Trojan cloud lies between several times 10−6 and 10−5. For Saturn, the probability is found to be in the range −6 to 10−5, whilst for Uranus the probabilities range between 10−5 and 10−4. Finally, Neptune displays the greatest probability of Trojan capture, with values ranging between 10−4 and 10−3. Our results suggest that all four giant planets are able to capture and retain a significant population of Trojan objects from the disc by the end of planetary migration. As a result of encounters with the giant planets prior to Trojan capture, these objects tend to be captured on orbits that are spread over a wide range of orbital eccentricities and inclinations. The bulk of captured objects are to some extent dynamically unstable, and therefore, the populations of these objects tend to decay over the age of the Solar system, providing an important ongoing source of new objects moving on dynamically unstable orbits among the giant planets. Given that a huge population of objects would be displaced by Neptune's outward migration (with a potential cumulative mass a number of times that of the Earth), we conclude that the surviving remnant of the Trojans captured during the migration of the outer planets might be sufficient to explain the currently known Trojan populations in the outer Solar system
Extension of low-thrust propulsion to the autonomous coplanar circular restricted four body problem with application to future Trojan Asteroid missions
No full textAn Autonomous Coplanar Circular Restricted Four Body Problem (CRFBP) is considered, where the massless body is a low-thrust spacecraft. 'Natural' and 'artificial' (i.e. created with the use of continuous low-thrust propulsion) equilibrium solutions are identified, that have the potential to be exploited in future science missions. Results show that, with zero thrust, there are unstable equilibrium points close to the third primary. However, artificial equilibrium points, displaced from the natural ones, can be generated with the use of constant low-thrust. Furthermore, these points are proved to be stable in certain regions about the third primary mass. This is particularly advantageous since it means that it would be possible to continuously maintain a spacecraft about these strategic observation points, close to the smaller primary, without the need for state feedback control. The Sun-Jupiter-Trojan Asteroid-Spacecraft system is considered, as a particular case of the Autonomous Coplanar CRFBP. Curves of artificial equilibrium points are then identified. Furthermore, the stability analysis of these points reveals the region where they are stable. In this region four bounded orbits close to the Asteroid are proved to exist, that can be reached and maintained with a constant low-thrust lower than 10µN
Theory of the Trojan Horse Method
No full textThe Trojan-Horse method is an indirect approach to determine the energy dependence of S factors of astrophysically relevant two-body reactions. This is accomplished by studying closely related three-body reactions under quasi-free scattering conditions. The basic theory of the Trojan-Horse method is developed starting from a post-form distorted wave Born approximation of the T-matrix element. In the surface approximation the cross-section of the three-body reaction can be related to the S-matrix elements of the two-body reaction. The essential feature of the Trojan-Horse method is the effective suppression of the Coulomb barrier at low energies for the astrophysical reaction leading to finite cross-sections at the threshold of the two-body reaction. In a modified plane wave approximation the relation between the two- and three-body cross-sections becomes very transparent. The appearing Trojan-Horse integrals are studied in detail. (C) 2003 Elsevier Science (USA). All rights reserved
Portland Junction, Trojan SD, Lawrence County
No full text3.5 x 3.5 b/w photograph, two well-worn paths veering in different directions1904-1975 Envelope 96-306 Black HillsLooking west up high grade at Portland Jct to Trojan The Miller Studio Jul 17 1963 Pierre S Da
The Trojan-Horse Method applied to the6Li(p,α)3He reaction down to astrophysical energies
No full textThe Trojan-Horse Method has been applied to the three-body d(6Li,alpha 3He)n breack-up reaction in order to extract the bare nucleus S(E) factor for the 6Li(p,alpha)3He reaction down to astrophysical energies
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