121,124 research outputs found
H. L. Biggs, and Cato Hightower
No full textH. L. Biggs, left, new policeman who was sworn with 10 other rookies, gets congratulations from the Police Chief Cato Hightower.https://mavmatrix.uta.edu/specialcollections_startelegram1950s/28274/thumbnail.jp
Optimal path planning for nonholonomic robotics systems via parametric optimisation
No full textAbstract. Motivated by the path planning problem for robotic systems this paper considers nonholonomic path planning on the Euclidean group of motions SE(n) which describes a rigid bodies path in n-dimensional Euclidean space. The problem is formulated as a constrained optimal kinematic control problem where the cost function to be minimised is a quadratic function of translational and angular velocity inputs. An application of the Maximum Principle of optimal control leads to a set of Hamiltonian vector field that define the necessary conditions for optimality and consequently the optimal velocity history of the trajectory. It is illustrated that the systems are always integrable when n = 2 and in some cases when n = 3. However, if they are not integrable in the most general form of the cost function they can be rendered integrable by considering special cases. This implies that it is possible to reduce the kinematic system to a class of curves defined analytically. If the optimal motions can be expressed analytically in closed form then the path planning problem is reduced to one of parameter optimisation where the parameters are optimised to match prescribed boundary conditions.This reduction procedure is illustrated for a simple wheeled robot with a sliding constraint and a conventional slender underwater vehicle whose velocity in the lateral directions are constrained due to viscous damping
[USA] 1:250 000 / B2-10 E,W Idaho - Montana Lolo quadrangle
No full textR. B. Marshall ; T. G. Gerdine ; T. M. Bannon ; J. G. Staack ; S. G. Lunde ; L. F. Biggs ; J. B. Lippincot
ESLO1: interview de personnalité 453
No full textExtrait du corpus d'Orléans, réalisé dans le cadre de l'Enquête SocioLinguistique à Orléans à la fin des années 1960.Société/cultureorganisation de la police (des polices) ; jeunesse actuelle, démission parentale ; objets trouvés, permis de séjour, accidents de circulation ; responsabilités police judiciaire ; grades ; CRS ; police supplétive ; gendarmerie mobile controlée de Paris. Fonctions du commissaire principal ; formation des diverses catégories de policiers ; rapport police/public ; rapport police/jeunes ; les étrangers ; police peu aimée ; besoin éclairer le public ; origines sentiments anti-policiers. Rôle des parents ; contact familial. Port d'armes : historique et explication. Rapports avec voisins ; répartition de la police suivant classes sociales ; Orléans ville fermée : appréciation générale ville.Autobiographie ; loisirs ; histoire famille.Ses poèmes ; modifications à apporter à la police.Témoin : M. L Homme (né en 1920 approx.), Chef de Sûreté. Enregistré par Michel Blanc Patricia Biggs Bernard Vernier Participants : M. L, Michel Blanc, Patricia Biggs et Bernard Vernier Lieu : au bureau du témoin Acoustique : médiocr
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Integrable quadratic Hamiltonians on the Euclidean group of motions
No full textIn this paper, we discuss the problem of globally computing sub-Riemannian curves on the Euclidean group of motions SE(3). In particular, we derive a global result for special sub-Riemannian curves whose Hamiltonian satisfies a particular condition. In this paper, sub-Riemannian curves are defined in the context of a constrained optimal control problem. The maximum principle is then applied to this problem to yield an appropriate left-invariant quadratic Hamiltonian. A number of integrable quadratic Hamiltonians are identified. We then proceed to derive convenient expressions for sub-Riemannian curves in SE(3) that correspond to particular extremal curves. These equations are then used to compute sub-Riemannian curves that could potentially be used for motion planning of underwater vehicles
Letter re: invitation
No full textLetter from Mrs. L. M. Biggs, mother-in-law of Electra Waggoner Biggs, to Amon Carter declining Carter's invitation to an unveiling of a statue of Will Rogers.Mrs. Biggs accepts with pleasure the invitation of Mr. Carter for luncheon, Tuesday November the fourth. L. M. B
Low thrust propulsion in a coplanar circular restricted four body problem
No full textThis paper formulates a circular restricted four body problem (CRFBP), where the three primaries are set in the stable Lagrangian equilateral triangle configuration and the fourth body is massless. The analysis of this autonomous coplanar CRFBP is undertaken, which identies eight natural equilibria; four of which are close to the smaller body, two stable and two unstable, when considering the primaries to be the Sun and two smaller bodies of the solar system. Following this, the model incorporates `near term' low-thrust propulsion capabilities to generate surfaces of articial equilibrium points close to the smaller primary, both in and out of the plane containing the celestial bodies. A stability analysis of these points is carried out and a stable subset of them is identied. Throughout the analysis the Sun-Jupiter-Asteroid-Spacecraft system is used, for conceivable masses of a hypothetical asteroid set at the libration point L4. It is shown that eight bounded orbits exist, which can be maintained with a constant thrust less than 1:5 10􀀀4N for a 1000kg spacecraft. This illustrates that, by exploiting low-thrust technologies, it would be possible to maintain an observation point more than 66% closer to the asteroid than that of a stable natural equilibrium point. The analysis then focusses on a major Jupiter Trojan: the 624-Hektor asteroid. The thrust required to enable close asteroid observation is determined in the simplied CRFBP model. Finally, a numerical simulation of the real Sun-Jupiter-624 Hektor-Spacecraft is undertaken, which tests the validity of the stability analysis of the simplied model
[USA] 1:250 000 / A4-2 NW California Big Bar and Vacinity
No full textR. B. Marshall ; T. G. Gerdine ; J. P. Harrison ; F. Urquhart ; A. I. Oliver ; L. F. Biggs ; G. C. Jacob
Numerical modelling of mud volcanoes and their flows using constraints from the Gulf of Cadiz
No full textIt is estimated that the total number of submarine mud volcanoes is between 1000 and 100 000. Because many are associated with greenhouse gases, such as methane, it is argued that the global flux of these gases to the atmosphere from the world’s terrestrial and submarine mud volcanoes is highly significant. Clues to the processes forming submarine mud volcanoes can be found in variations to their height, shape, surface morphology, physical properties and internal structure. A model of isostatic compensation between the mud column and the sediment overlying the mud source is used to predict a depth to the mud reservoir beneath mud volcanoes. Once erupted, the general behaviour of an individual mud flow can be described and predicted using a viscous gravity-current model. The model shows that conical-shaped mud volcanoes comprise multiple, superimposed radial flows in which the thickness, eruption rate and speed of individual mud flows strongly depends on the viscosity, density and over-pressure of the erupted mud. Using these parameters, the model predicts the lowermost flows will be the oldest, thickest and have the greatest length of run-out while the uppermost flows will be the youngest, thinnest and shortest. This model is in contrast to more traditional models of stratiform mud volcano construction in which younger flows progressively bury older ones and travel furthest from the summit. Applying the model to the two mud volcanoes studied in the Gulf of Cadiz, quantitative estimates are derived for the depths to mud sources, exit and flow velocities, eruption duration and volume fluxes, flow thickness and conduit radii. For example, with an average kinematic viscosity of 1.5 m2 s?1 for the erupted mud, a density of 1.8×103 kg m?3 and a thickness for the youngest flows of about 0.5 m, the model predicts a lowermost flow thickness of 3.6 m, an average eruption duration of 7 h and a conduit radius of about 9 m. To construct a conical-shaped mud volcano of 260 m height, similar to those studied in the Gulf of Cadiz, is estimated to require a mud source at 4.6 km depth and a total of at least 100 individually erupted flows
Path planning for simple wheeled robots : sub-Riemannian and elastic curves on SE(2)
No full textThis paper presents a motion planning method for a simple wheeled robot in two cases: (i) where translational and rotational speeds are arbitrary and (ii) where the robot is constrained to move forwards at unit speed. The motions are generated by formulating a constrained optimal control problem on the Special Euclidean group SE(2). An application of Pontryagin’s maximum principle for arbitrary speeds yields an optimal Hamiltonian which is completely integrable in terms of Jacobi elliptic functions. In the unit speed case, the rotational velocity is described in terms of elliptic integrals and the expression for the position reduced to quadratures. Reachable sets are defined in the arbitrary speed case and a numerical plot of the time-limited reachable sets presented for the unit speed case. The resulting analytical functions for the position and orientation of the robot can be parametrically optimised to match prescribed target states within the reachable sets. The method is shown to be easily adapted to obstacle avoidance for static obstacles in a known environment
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