101,092 research outputs found
Concentration of the distance between points in the unit ball
No full textWe prove that in every finite dimensional normed space, for “most” pairs (x, y) of points in the unit ball, ║x − y║ is more than √2(1 − ε). As a consequence, we obtain a result proved by Bourgain, using QS-decomposition, that guarantees an exponentially large number of points in the unit ball any two of which are separated by more than √2(1 − ε)
Generating ball trajectory in soccer video sequences
No full textThis paper demonstrates innovative techniques for estimating the trajectory of a soccer ball, using fixed cameras with constant calibration parameters. In contrast with broadcast coverage, for fixed camera data, the ball is often rendered with poor resolution away from the image centre. The rapidly moving ball is subject to motion-blur, caused by finite shutter speeds and interlaced fields, resulting in variable shape, size and colour. The velocity estimated from Kalman tracking is used in both normalising ball size and filtering the ball from false alarms. Furthermore, occlusion-reasoning and tracking-back methods are utilized to estimate its position when it is occluded, and also to remove false alarms. Finally, temporal hysteresis based thresholding of the ball likelihood is applied for trajectory filtering to improve the robustness and continuity of the tracked ball. Promising experimental results from several long sequences are reported
The Influence of Co-designers on the Generation and Evaluation of Solution Alternatives.
No full textAdelson B, Soloway A (1986) A model of software design. International Journal of Intelligent Systems 1: 195-213 Ball LJ, Evans JStBT, Dennis I (1994) Cognitive processes in engineering design: A longitudinal study. Ergonomics 37: 1753-1786 Ball LJ, Lambell NJ, Ormerod TC, Slavin S, Mariani JA (2000) Representing design rationale to support innovative design re-use: A minimalist approach. Automation in Construction, in press Ball LJ, Maskill L, Ormerod TC (1998) Satisficing in engineering design: Causes, consequences and implications for design support. Automation in Construction 7: 213-227 Ball LJ, Ormerod TC (2000) Putting ethnography to work: The case for a cognitive ethnography of design. International Journal of Human-Computer Studies, in press Cross N (1994) Engineering design methods: Strategies for product design, 2nd edn. Wiley, Chichester Gero JS (1990) Design prototypes: A knowledge representation schema for design. AI Magazine 11: 26-36 Jeffries R, Turner AA, Polson PG, Atwood ME (1981) The processes involved in designing software. In: Anderson JR (ed.) Cognitive skills and their acquisition. Erlbaum, Hillsdale, NJ, pp 255-283 Kant E (1985) Understanding and automating the algorithm design process. In: Proceedings of the International Joint Conference on Artificial Intelligence. Morgan Kaufmann, Los Altos, CA, pp 211-219 MacLean A, Young RM, Bellotti VME, Moran TP (1991) Questions, Options, and Criteria: Elements of design space analysis. Human-Computer Interaction 6: 201-250 Olson GM. Olson JS, Carter MR, Storrøsten M (1992) Small group design meetings: An analysis of collaboration. Human-Computer Interaction 7: 347-374 Olson GM, Olson JS, Storrøsten M, Carter MR, Herbsleb J, Rueter H (1996) The structure of activity during design meetings. In: Moran TP, Carroll, JM (eds.) Design rationale: Concepts, techniques, and use. Lawrence Erlbaum Associates, Mahwah, NJ pp 217-239 Ormerod TC, Mariani JA, Ball LJ, Lambell NJ (1999) Desperado: Three-in-one indexing for innovative design. In: Sasse MA, Johnson, C (eds.) Proceedings of the Seventh IFIP Conference on Human-Computer Interaction—INTERACT ’99. IOS Press, London, pp 336-343 Pahl G, Beitz W (1984) Engineering design. The Design Council, London [Original German text, 1977, Springer-Verlag, Berlin]. Pugh S (1991) Total design: Integrated methods for successful product engineering. Addison-Wesley, London Simon HA (1981) The sciences of the artificial, 2nd edn. MIT Press, Cambridge, MA Ullman DG, Dietterich TG, Stauffer LA (1988) A model of the mechanical design process based on empirical data. Artificial Intelligence for Engineering Design, Analysis and Manufacturing 2: 33-5
A Study of Diagnostic Signatures of a Deep Groove Ball Bearing Based on a Nonlinear Dynamic Mode
No full textFor accurate fault detection and diagnosis, this paper focuses on the study of bearing vibration responses under increasing radial clearances due to investable wear and different bearing grades. A nonlinear dynamic model incorporating with local defects and clearance increments is developed for a deep groove ball bearing. The model treats the inner race-shaft and outer race-housing as two lumped masses which are coupled by a nonlinear spring formalized by the Hertzian contact deformation between the balls and races. The solution of the nonlinear equation is obtained by a Runge-Kutta method in Matlab. The results show that the vibrations at fault characteristic frequencies exhibit significant changes with increasing clearances. However, an increased vibration is found for the outer race fault whereas a decreased vibration is found for inner race fault. Therefore, it is necessary to take into account these changes in determining the size of faults
Parametric impact characterisation of a solid sports ball, WITH a view to developing a standard core for the GAA Sliotar
Full text linkThe main aim of this research was to characterise the dynamic impact behaviour of the sliotar core. Viscoelastic characterisation of the balls was conducted for a range of impact speeds. Modern polymer balls exhibited strain and strain-rate sensitivity while traditional multi-compositional balls exhibited strain dependency. The non-linear viscoelastic response was defined by two values of stiffness, initial and bulk stiffness.
Traditional balls were up to 2.5 times stiffer than the modern types, with this magnitude being rate-dependent. The greater rate of increase of traditional ball stiffness produced a more non-linear COR velocity-dependence compared to modern balls. The dynamic stiffness results demonstrated limited applicability of quasi-static testing and springtheory equations. Analysis of ball deformation behaviour demonstrated that centre-of mass displacement and diameter compression values were not consistently equivalent for all ball types. The contribution of manufacturing conditions to ball performance was investigated by conducting extensive prototyping experiments. Manufacturing parameters of temperature, pressure and material composition were varied to produce a range of balls. Polymer hardness affected stiffness but not energy dissipation, with increased hardness increasing ball stiffness. The nucleating additive influenced ball COR, with increased additive tending to reduce ball COR, but this effect was sensitive to polymer grade. The impact response of the ball was simulated using three mathematical models. The first model was shown to replicate ball behaviour to only a limited degree, despite being used previously with reported success for other ball types. The second model exhibited a reasonable representation of ball impact response that was universally applicable to all tested ball types; however, the accuracy in terms of predicting force-displacement response was not as high as required for broad range implementation. The third model exhibited significantly better accuracy in simulating ball response. The force values generated from this model exhibited up to 95% agreement with experimental data
Tracking the soccer ball using multiple fixed cameras
No full textThis paper demonstrates innovative techniques for estimating the trajectory of a soccer ball from multiple fixed cameras. Since the ball is nearly always moving and frequently occluded, its size and shape appearance varies over time and between cameras. Knowledge about the soccer domain is utilized and expressed in terms of field, object and motion models to distinguish the ball from other movements in the tracking and matching processes. Using ground plane velocity, longevity, normalized size and color features, each of the tracks obtained from a Kalman filter is assigned with a likelihood measure that represents the ball. This measure is further refined by reasoning through occlusions and back-tracking in the track history. This can be demonstrated to improve the accuracy and continuity of the results. Finally, a simple 3D trajectory model is presented, and the estimated 3D ball positions are fed back to constrain the 2D processing for more efficient and robust detection and tracking. Experimental results with quantitative evaluations from several long sequences are reported
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
Full text linkFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Fatou and Korányi-Vági type theorems on the minimal ball
Full text linkIn this paper we develop the Hp (p [greater than or equal] 1) theory on the minimal ball. After identifying the admissible approach regions, we establish theorems of Fatou and Korányi-Vági type on this ball
Mrs. J. M. Patton at the Opera Ball
No full textMrs. J. M. Patton is photographed snuggled up to a large stuffed giraffe, which is one of the hundred gifts at the Opera Ball at the Ridglea Country Club. Mrs. Patton is shown wearing a long black dress with a pearl necklace. Fort Worth Star-Telegram Morning edition October 9, 1967.https://mavmatrix.uta.edu/specialcollections_startelegram1960s/4177/thumbnail.jp
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