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[en] Necessary and sufficient conditions for the transfer function of a passive linear stationary scattering (or resistance) system are found ensuring that minimal systems in this class are determined by their transfer functions up to similarity. The criteria are stated in terms of a Hankel operator the symbol of which is a contractive operator-valued function defined by the transfer function and having the meaning of the inner scattering suboperator of a simple conservative scattering (respectively, resistance) system with the transfer function in question. A connection between the similarity criterion and the corona theorem and its matrix generalizations is revealed
[en] The beam transfer function changes during the RHIC ramp. The response of the RF control loops changes as a result. A state-variable description of the beam and the RF control loops was developed. This description was used to generate a set of feedback matrices that keeps the response of the RF control loops constant during the ramp. This paper describes the state-variable description and its use in determining the K matrices
[en] Bridging the gap between an abstract definition of pseudo-differential operators, such as (-Δ)γ for -1/2<γ<1/2, and a concrete way to represent them has proved difficult; deriving stable numerical schemes for such operators is not an easy task either. Thus, the framework of diffusive representations, as already developed for causal fractional integrals and derivatives, is being applied to fractional Laplacian: it can be seen as an extension of the Wiener-Hopf factorization and splitting techniques to irrational transfer functions.
[en] This note will tabulate the desired phase and delay offsets for a Stacktail Momentum beam transfer function measurement as a function of beam energy and pickup leg. These phase and delay offsets were computed from beam transfer functions made around April 14, 2000. The StackTail system with these offsets will have a gain slope of about 10 MeV.
[en] Synchronous detection offers an especially powerful instrument of investigation. It enables a signal to be extracted from the noise by narrowing of the analysis band at the expense of the examination time, and in this sense constitutes a very narrow filter synchronised externally on the signal to be examined. It is phase-sensitive, a great advantage in the determination of transfer functions
[fr]La detection synchrone constitue un instrument d'investigation particulierement puissant. Elle permet d'extraire un signal du bruit par retrecissement de la bande d'analyse au detriment du temps d'examen. En ce sens, elle constitue un filtre tres etroit synchronise exterieurement sur le signal a examiner. Elle est sensible a la phase. Cette sensibilite est tres avantageuse lors de la determination de fonctions de transfert
[en] It is important to monitor the spatial resolution of a gamma camera on a weekly basis to acquire medical images with accurate quantitative information. A simple and fast computer program with a graphical user interface to analyze spatial resolution was successfully developed using MATLAB. The results were compared with those obtained from the standard processing system available in our gamma camera. The spatial resolution calculated using MATLAB was 1.24% lower than using the standard processing system. The developed program is cost effective, faster, and provides an easy platform for the physicists and technologists to analyze the spatial resolution based on the image of the line source.
[en] When a person observes an object located at a distance closer than his near point, the object will appear blurred. Inserting a circular pinhole with a suitable diameter in front of the eye improves vision. However, vision worsens below a certain pinhole diameter, due to diffraction and increasing darkness. In this paper, the effect of the pinhole diameter on observation quality is investigated by determining the optical transfer function of the eye lens–pinhole system. A quantity that is a criterion for image quality is defined, then, it is calculated as a function of the pinhole diameter. This treatment shows that, even for a definite eye, the optimum and also minimum values of pinhole diameter depend on the object distance. (paper)