13,190 research outputs found
Constrained optimal control theory for differential linear repetitive processes
Differential repetitive processes are a distinct class of continuous-discrete two-dimensional linear systems of both systems theoretic and applications interest. These processes complete a series of sweeps termed passes through a set of dynamics defined over a finite duration known as the pass length, and once the end is reached the process is reset to its starting position before the next pass begins. Moreover the output or pass profile produced on each pass explicitly contributes to the dynamics of the next one. Applications areas include iterative learning control and iterative solution algorithms, for classes of dynamic nonlinear optimal control problems based on the maximum principle, and the modeling of numerous industrial processes such as metal rolling, long-wall cutting, etc. In this paper we develop substantial new results on optimal control of these processes in the presence of constraints where the cost function and constraints are motivated by practical application of iterative learning control to robotic manipulators and other electromechanical systems. The analysis is based on generalizing the well-known maximum and -maximum principles to the
Optical fiber interferometer for the study of ultrasonic waves in composite materials
The possibility of acoustic emission detection in composites using embedded optical fibers as sensing elements was investigated. Optical fiber interferometry, fiber acoustic sensitivity, fiber interferometer calibration, and acoustic emission detection are reported. Adhesive bond layer dynamical properties using ultrasonic interface waves, the design and construction of an ultrasonic transducer with a two dimensional Gaussian pressure profile, and the development of an optical differential technique for the measurement of surface acoustic wave particle displacements and propagation direction are also examined
Mapping the Kinematical Regimes of Semi-Inclusive Deep Inelastic Scattering
We construct a language for identifying kinematical regions of transversely
differential semi-inclusive deep inelastic scattering cross sections with
particular underlying partonic pictures, especially in regions of moderate to
low where sensitivity to kinematical effects outside the usual very high
energy limit becomes non-trivial. The partonic pictures map to power law
expansions whose leading contributions ultimately lead to well-known QCD
factorization theorems. We propose methods for estimating the consistency of
any particular region of overall hadronic kinematics with the kinematics of a
given underlying partonic picture. The basic setup of kinematics of
semi-inclusive deep inelastic scattering is also reviewed in some detail.Comment: 37 pages, 11 Figure
Second Language Feedback Abolishes the “Hot Hand” Effect during Even-Probability Gambling
Research into language�emotion interactions has revealed intriguing cognitive inhibition effects by emotionally negative words in bilinguals. Here, we turn to the domain of human risk taking and show that the experience of positive recency in games of chance�the �hot hand� effect�is diminished when game outcomes are provided in a second language rather than the native language. We engaged late Chinese-English bilinguals with �play� or �leave� decisions upon presentation of equal-odds bets while manipulating language of feedback and outcome value. When positive game outcomes were presented in their second language, English, participants subsequently took significantly fewer gambles and responded slower compared with the trials in which equivalent feedback was provided in Chinese, their native language. Positive feedback was identified as driving the cross-language difference in preference for risk over certainty: feedback for previous winning outcomes presented in Chinese increased subsequent risk taking, whereas in the English context no such effect was observed. Complementing this behavioral effect, event-related brain potentials elicited by feedback words showed an amplified response to Chinese relative to English in the feedback-related negativity window, indicating a stronger impact in the native than in the second language. We also observed a main effect of language on P300 amplitude and found it correlated with the cross-language difference in risk selections, suggesting that the greater the difference in attention between languages, the greater the difference in risk-taking behavior. These results provide evidence that the hot hand effect is at least attenuated when an individual operates in a non-native language
Evocative computing – creating meaningful lasting experiences in connecting with the past
We present an approach – evocative computing – that demonstrates how ‘at hand’ technologies can be ‘picked up’ and used by people to create meaningful and lasting experiences, through connecting and interacting with the past. The approach is instantiated here through a suite of interactive technologies configured for an indoor-outdoor setting that enables groups to explore, discover and research the history and background of a public cemetery. We report on a two-part study where different groups visited the cemetery and interacted with the digital tools and resources. During their activities serendipitous uses of the technology led to connections being made between personal memo-ries and ongoing activities. Furthermore, these experiences were found to be long-lasting; a follow-up study, one year later, showed them to be highly memorable, and in some cases leading participants to take up new directions in their work. We discuss the value of evocative computing for enriching user experiences and engagement with heritage practices
Fermionic solution of the Andrews-Baxter-Forrester model II: proof of Melzer's polynomial identities
We compute the one-dimensional configuration sums of the ABF model using the
fermionic technique introduced in part I of this paper. Combined with the
results of Andrews, Baxter and Forrester, we find proof of polynomial
identities for finitizations of the Virasoro characters
as conjectured by Melzer. In the thermodynamic limit
these identities reproduce Rogers--Ramanujan type identities for the unitary
minimal Virasoro characters, conjectured by the Stony Brook group. We also
present a list of additional Virasoro character identities which follow from
our proof of Melzer's identities and application of Bailey's lemma.Comment: 28 pages, Latex, 7 Postscript figure
Correction to: Stereotactic radiosurgery and radiotherapy for resected brain metastases: current pattern of care in the Radiosurgery and Stereotactic Radiotherapy Working Group of the German Association for Radiation Oncology (DEGRO)
Recent Decisions
Comments on recent decisions by Lawrence A. Kane, Jr., Vernon O. Teofan, Thomas S. Calder, John Rogers, James Carroll Booth, Paul M. Kraus, Jack Economou, and Robert P. Gorman
Reflection and Ducting of Gravity Waves Inside the Sun
Internal gravity waves excited by overshoot at the bottom of the convection
zone can be influenced by rotation and by the strong toroidal magnetic field
that is likely to be present in the solar tachocline. Using a simple Cartesian
model, we show how waves with a vertical component of propagation can be
reflected when traveling through a layer containing a horizontal magnetic field
with a strength that varies with depth. This interaction can prevent a portion
of the downward-traveling wave energy flux from reaching the deep solar
interior. If a highly reflecting magnetized layer is located some distance
below the convection zone base, a duct or wave guide can be set up, wherein
vertical propagation is restricted by successive reflections at the upper and
lower boundaries. The presence of both upward- and downward-traveling
disturbances inside the duct leads to the existence of a set of horizontally
propagating modes that have significantly enhanced amplitudes. We point out
that the helical structure of these waves makes them capable of generating an
alpha-effect, and briefly consider the possibility that propagation in a shear
of sufficient strength could lead to instability, the result of wave growth due
to over-reflection.Comment: 23 pages, 5 figures. Accepted for publication in Solar Physic
The Polyakov action on the supertorus
A consistent method for obtaining a well-defined Polyakov action on the
supertorus is presented. This method uses the covariantization of derivative
operators and enables us to construct a Polyakov action which is globally
defined.Comment: 15 pages LaTe
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