440,543 research outputs found
A high accuracy computed water line list
A computed list of HO infra-red transition frequencies and
intensities is presented. The list, BT2, was produced using a discrete variable
representation two-step approach for solving the rotation-vibration nuclear
motions. It is the most complete water line list in existence, comprising over
500 million transitions (65% more than any other list) and it is also the most
accurate (over 90% of all known experimental energy levels are within 0.3
cm of the BT2 values). Its accuracy has been confirmed by extensive
testing against astronomical and laboratory data.
The line list has been used to identify individual water lines in a variety
of objects including: comets, sunspots, a brown dwarf and the nova-like object
V838 Mon. Comparison of the observed intensities with those generated by BT2
enables physical values to be derived for these objects. The line list can also
be used to provide an opacity for models of the atmospheres of M-dwarf stars
and assign previously unknown water lines in laboratory spectra.Comment: 8 Pages, zero figures. Submitted to MNRAS. On line data at:
ftp://cdsarc.u-strasbg.fr/cats/VI/11
High accuracy optical rate sensor
Optical rate sensors, in particular CCD arrays, will be used on Space Station Freedom to track stars in order to provide inertial attitude reference. An algorithm to provide attitude rate information by directly manipulating the sensor pixel intensity output is presented. The star image produced by a sensor in the laboratory is modeled. Simulated, moving star images are generated, and the algorithm is applied to this data for a star moving at a constant rate. The algorithm produces accurate derived rate of the above data. A step rate change requires two frames for the output of the algorithm to accurately reflect the new rate. When zero mean Gaussian noise with a standard deviation of 5 is added to the simulated data of a star image moving at a constant rate, the algorithm derives the rate with an error of 1.9 percent at a rate of 1.28 pixels per frame
Method for High Accuracy Multiplicity Correlation Measurements
Multiplicity correlation measurements provide insight into the dynamics of
high energy collisions. Models describing these collisions need these
correlation measurements to tune the strengths of the underlying QCD processes
which influence all observables. Detectors, however, often possess limited
coverage or reduced efficiency that influence correlation measurements in
obscure ways. In this paper, the effects of non-uniform detection acceptance
and efficiency on the measurement of multiplicity correlations between two
distinct detector regions (termed forward-backward correlations) are derived.
An analysis method with such effects built-in is developed and subsequently
verified using different event generators. The resulting method accounts for
acceptance and efficiency in a model independent manner with high accuracy
thereby shedding light on the relative contributions of the underlying
processes to particle production.Comment: 28 pages, 13 figures. Updated for having pseudorapidity dependent
efficiency gradient
High Accuracy Fuel Flowmeter, Phase 1
Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation
A Framework for High-Accuracy Privacy-Preserving Mining
To preserve client privacy in the data mining process, a variety of
techniques based on random perturbation of data records have been proposed
recently. In this paper, we present a generalized matrix-theoretic model of
random perturbation, which facilitates a systematic approach to the design of
perturbation mechanisms for privacy-preserving mining. Specifically, we
demonstrate that (a) the prior techniques differ only in their settings for the
model parameters, and (b) through appropriate choice of parameter settings, we
can derive new perturbation techniques that provide highly accurate mining
results even under strict privacy guarantees. We also propose a novel
perturbation mechanism wherein the model parameters are themselves
characterized as random variables, and demonstrate that this feature provides
significant improvements in privacy at a very marginal cost in accuracy.
While our model is valid for random-perturbation-based privacy-preserving
mining in general, we specifically evaluate its utility here with regard to
frequent-itemset mining on a variety of real datasets. The experimental results
indicate that our mechanisms incur substantially lower identity and support
errors as compared to the prior techniques
High Accuracy Near-infrared Imaging Polarimetry with NICMOS
The findings of a nine orbit calibration plan carried out during HST Cycle
15, to fully determine the NICMOS camera 2 (2.0 micron) polarization
calibration to high accuracy, are reported. Recently Ueta et al. and Batcheldor
et al. have suggested that NICMOS possesses a residual instrumental
polarization at a level of 1.2-1.5%. This would completely inhibit the data
reduction in a number of GO programs, and hamper the ability of the instrument
to perform high accuracy polarimetry. We obtained polarimetric calibration
observations of three polarimetric standards at three spacecraft roll angles
separated by ~60deg. Combined with archival data, these observations were used
to characterize the residual instrumental polarization in order for NICMOS to
reach its full potential of accurate imaging polarimetry at p~1%. Using these
data, we place an 0.6% upper limit on the instrumental polarization and
calculate values of the parallel transmission coefficients that reproduce the
ground-based results for the polarimetric standards. The uncertainties
associated with the parallel transmission coefficients, a result of the
photometric repeatability of the observations, are seen to dominate the
accuracy of p and theta. However, the updated coefficients do allow imaging
polarimetry of targets with p~1.0% at an accuracy of +/-0.6% and +/-15deg. This
work enables a new caliber of science with HST.Comment: 13 pages, 9 figures, PASP accepte
- …
