54,164 research outputs found
Optimalizing control in the presence of noise interference
The performance of a modified peak-holding optimalizing
control system depends in part on the ability of the
controller to detect the input signal frequency component
in the output of the controlled system. This paper describes
several techniques that may be used for detecting this component and analyzes one of them in great detail.
The subject of the detailed analysis is the method of filtering through cross-correlation. A statistical analysis is also carried out in order to demonstrate the efficiency of this method
Pulse processing routines for neutron time-of-flight data
A pulse shape analysis framework is described, which was developed for
n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN.
The most notable feature of this new framework is the adoption of generic pulse
shape analysis routines, characterized by a minimal number of explicit
assumptions about the nature of pulses. The aim of these routines is to be
applicable to a wide variety of detectors, thus facilitating the introduction
of the new detectors or types of detectors into the analysis framework. The
operational details of the routines are suited to the specific requirements of
particular detectors by adjusting the set of external input parameters. Pulse
recognition, baseline calculation and the pulse shape fitting procedure are
described. Special emphasis is put on their computational efficiency, since the
most basic implementations of these conceptually simple methods are often
computationally inefficient.Comment: 13 pages, 10 figures, 5 table
High Efficiency Power Amplifier Based on Envelope Elimination and Restoration Technique
Due to complex envelope and phase modulation employed in modern transmitters it is necessary to use power amplifiers that have high linearity. Linear power amplifiers (classes A, B and AB) are commonly used, but they suffer from low efficiency especially if the transmitted signal has high peak to average power ratio (PAPR). Kahn's technique based on envelope elimination and restoration (EER) is based on idea that high efficiency power supply (envelope amplifier) could be used to modulate the envelope of high efficient non linear power amplifiers (classes D or E). This paper presents solutions for power amplifier that performs envelope modulation and class E amplifier that is used as a non linear amplifier. The envelope amplifier is implemented as a multilevel converter in series with linear regulator and can provide up to 100 W of instantaneous power and reproduce 2 MHz sine wave. The implemented Class E amplifier can operate at 120 MHz with efficiency near to 85%. The envelope amplifier and class E amplifier have been integrated and efficiency and linearity of the implemented transmitter has been measured and presente
High Redshift Supernovae in the Hubble Deep Field
Two supernovae detected in the Hubble Deep Field using the original December
1995 epoch and data from a shorter (63000 s in F814W) December 1997 visit with
HST are discussed. The supernovae (SNe) are both associated with distinct
galaxies at redshifts of 0.95 (spectroscopic) from Cohen etal. (1996) and 1.32
(photometric) from the work of Fernandez-Soto, Lanzetta, and Yahil (1998).
These redshifts are near, in the case of 0.95, and well beyond for 1.32 the
greatest distance reported previously for SNe. We show that our observations
are sensitive to SNe to z < 1.8 in either epoch for an event near peak
brightness. Detailed simulations are discussed that quantify the level at which
false events from our search phase would start to to arise, and the
completeness of our search as a function of both SN brightness and host galaxy
redshift. The number of Type Ia and Type II SNe expected as a function of
redshift in the two HDF epochs are discussed in relation to several published
predictions and our own detailed calculations. A mean detection frequency of
one SN per epoch for the small HDF area is consistent with expectations from
current theory.Comment: 62 pages, 17 figures, ApJ 1999 in pres
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