223,537 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)
Paradigm lecture series: Rob Ball
No full textThe Photography program presents a talk by British photographer Rob Ball as part of its Paradigm Lecture Series.
Rob Ball is interested in materiality, temporality and process. Working predominantly with tintype, Ball constructs darkrooms in-situ, ensuring photographic plates are both created and developed in the location depicted. Ball’s current practice centers on the physical nature of making a tintype image and the experience this creates for the artist, sitter and viewer. Working often as an itinerant, Ball engages with the history of the medium and its repeated obsolescence to generate new creative engagement and thinking
Ball Family, Woods Park, Nebraska
No full text'One among the very early settlers.' Identification of the individuals was submitted by the daughter of Elmer Ball; From l-r: George Ball, Mrs. George Ball, Elmer D. Ball, Vera Ball, Vaughn Ball (infant), Ella Ball, Lillie Ball-Chihallin, Ethel Ball
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
Talk: Miniclick does summer holidays with Rob Ball and William Lakin, 11th july
No full textRob Ball
Between around 1880 and World War II, Coney Island was the largest amusement area in the United States attracting several million visitors each year. At its height, three enormous amusement parks – Luna Park, Dreamland, and Steeplechase Park – competed for visitors with the latest thrills and spills. Consequently Coney Island became a focus for the latest technological innovation, with electric lights, roller coasters, and even baby incubators appearing there in the 1900s.
Rob Ball explores Coney Island to tell a story of a resort rich in history and with a special cultural significance for many New Yorkers. Ball articulates this historical context through the use of the handmade and unpredictable tintype process, once widely used in Coney Island. This is balanced by his colour work documenting the area’s current diversity and popularity, with images made during the busy summer period.
For Ball, this is part of long-term photographic project engaging with the history of coastal resorts and their cyclical rise and fall in popularity. It is also a sequel to his previous book, Dreamlands, that looked at the popular amusement park in Margate. As with Margate, Coney Island in Brooklyn has undergone a period of repair after years of neglect and this is reflected in the work
The Development and Assessment of Core Strength Clinical Measures: Validity and Reliability of Medicine Ball Toss Tests
No full textCore strengthening has become a significant focus in physical fitness, performance training, injury prevention, and rehabilitation. Core strength is theorized to optimize athletic performance, reduce risk of injury, and facilitate return from injury. Reliable and valid measures of core strength are necessary to track progress and determine effectiveness of human performance training. The purpose of this study was to determine the reliability and validity of three medicine ball toss tests. A total of 20 healthy physically active males and females (Age: 22.7±7.8 years, Height: 164.79±25.70 cm, Weight: 70.95±12.34 kg) participated. Testing occurred in two sessions separated by one to seven days. During session one, isokinetic testing was performed followed by medicine ball toss tests. Isokinetic strength testing included torso flexion, extension, and rotation, standardized according to manufacturer’s recommendations. Medicine ball toss tests were performed in four directions: forwards, backward, and rotational (right/left). Subjects performed five practice trials of each throw, followed by a five-minute rest period. Following the rest period, subjects performed five measured medicine ball toss tests. Subjects performed only the medicine ball toss tests in session two. Average peak torque was utilized for analysis of isokinetic strength. The average distance of the first three medicine ball toss tests in each direction was utilized for analysis. Pearson correlations were calculated to assess validity between medicine ball toss tests in session one and the corresponding isokinetic strength. Intraclass correlation coefficients were calculated to determine the reliability of the medicine ball toss tests between sessions. No significant Pearson correlations were observed between the forward, backward, and rotational medicine ball toss tests and corresponding measures of isokinetic strength (r=-0.047, p=0.845; r=-0.074, p=0.756; r=-0.051, p=0.832 (right); r=0.18, p=0.447 (left), respectively). Significant intraclass correlations were observed between session one and two medicine ball toss tests (ICC=0.835; ICC=0.835; ICC=0.870 (right); ICC=0.909 (left); p<0.001, respectively). These results illustrate that medicine ball toss tests have excellent reliability but are not valid against isokinetic strength, indicating that modifications to these medicine ball toss tests may be necessary. Future research should focus on preserving reliability while establishing validity of these medicine ball toss tests through appropriate modifications
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
Stability of a spherical flame ball in a porous medium
No full textGaseous flame balls and their stability to symmetric disturbances are studied numerically and asymptotically, for large activation temperature, within a porous medium that serves only to exchange heat with the gas. Heat losses to a distant ambient environment, affecting only the gas, are taken to be radiative in nature and are represented using two alternative models. One of these treats the heat loss as being constant in the burnt gases and linearizes the radiative law in the unburnt gas (as has been studied elsewhere without the presence of a solid). The other does not distinguish between burnt and unburnt gas and is a continuous dimensionless form of Stefan's law, having a linear part that dominates close to ambient temperatures and a fourth power that dominates at higher temperatures.Numerical results are found to require unusually large activation temperatures in order to approach the asymptotic results. The latter involve two branches of solution, a smaller and a larger flame ball, provided heat losses are not too high. The two radiative heat loss models give completely analogous steady asymptotic solutions, to leading order, that are also unaffected by the presence of the solid which therefore only influences their stability. For moderate values of the dimensionless heat-transfer time between the solid and gas all flame balls are unstable for Lewis numbers greater than unity. At Lewis numbers less than unity, part of the branch of larger flame balls becomes stable, solutions with the continuous radiative law being stable over a narrower range of parameters. In both cases, for moderate heat-transfer times, the stable region is increased by the heat capacity of the solid in a way that amounts, simply, to decreasing an effective Lewis number for determining stability, just as if the heat-transfer time was zero
Fatou and Korányi-Vági type theorems on the minimal ball
No full textIn 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
Poly(isoprenecarboxylates) from Glucose via Anhydromevalonolactone
No full textThe raw data files are organized within folders by the instrumentation used for characterization or by the chemdraw file. The characterization files are labeled by the number given to each molecule in the main text of the document.These are raw data files obtained during development of the following manuscript: Ball-Jones, N. R.; Fahnhorst, G. W.; Hoye, T.R. "Poly(isoprenecarboxylates) from Glucose via Anhydromevalonolactone" ACS Macro Lett. 2016, 1128–1131. The abstract of this document is the following, "A short and efficient synthesis of a series of isoprenecarboxylic acid esters and their corresponding polymers is presented. The base-catalyzed eliminative ring opening of anhydromevalonolactone (3) provides isoprenecarboxylic acid (6-H), which was further transformed to the isoprenecarboxylic acid esters. Reversible addition–fragmentation chain-transfer (RAFT) polymerization was used to synthesize high molecular weight (>100 kg mol–1) poly(isoprenecarboxylates) with dispersities (Đ) of ca. 1.5. The glass transition temperatures (Tg) and entanglement molecular weights (Me) of the poly(isoprenecarboxylates) were determined and showed similar trends to the Tg and Me values for analogous poly(acrylate esters). These new glucose-derived materials could provide a sustainable alternative to poly(acrylates).Ball-Jones, Nicolas; Hoye, Thomas R.; Fahnhorst, Grant W.. (2018). Poly(isoprenecarboxylates) from Glucose via Anhydromevalonolactone. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/D6FH5H
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