96,235 research outputs found
Measurements of alpha_s from hadronic event shapes in e+e- annihilation
New studies of hadronic event shape observables in e+ e- collisions between
13 and 183 GeV CM energy have enabled the running of alpha_s to be confirmed
and the validity of non-perturbative power-law corrections to be investigated.
A more precise value of alpha_s(M_Z) with reduced theoretical errors has been
reported from fitting 18 oriented event shape distributions measured in one
experiment at the Z.Comment: 3 pages, 2 figures, ICHEP Vancouver, Canada, 199
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Testing based on the RELAY model of error detection
RELAY, a model for error detection, defines revealing conditions that guarantee that a fault originates an error during execution and that the error transfers through computations and data flow until it is revealed. This model of error detection provides a fault-based criterion for test data selection. The model is applied by choosing a fault classification, instantiating the conditions for the classes of faults, and applying them to the program being tested. Such an application guarantees the detection of errors caused by any fault of the chosen classes. As a formal mode of error detection, RELAY provides the basis for an automated testing tool. This paper presents the concepts behind RELAY, describes why it is better than other fault-based testing criteria, and discusses how RELAY could be used as the foundation for a testing system
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An analysis of test data selection criteria using the RELAY model of fault detection
RELAY is a model of faults and failures that defines failure conditions, which describe test data for which execution will guarantee that a fault originates erroneous behavior that also transfers through computations and information flow until a failure is revealed. This model of fault detection provides a framework within which other testing criteria's capabilities can be evaluated. In this paper, we analyze three test data selection criteria that attempt to detect faults in six fault classes. This analysis shows that none of these criteria is capable of guaranteeing detection for these fault classes and points out two major weaknesses of these criteria. The first weakness is that the criteria do not consider the potential unsatisfiability of their rules; each criterion includes rules that are sufficient to cause potential failures for some fault classes, yet when such rules are unsatisfiable, many faults may remain undetected. Their second weakness is failure to integrate their proposed rules; although a criterion may cause a subexpression to take on an erroneous value, there is no effort made to guarantee that the intermediate values cause observable, erroneous behavior. This paper shows how the RELAY model overcomes these weaknesses
The Supernova-Gamma Ray Burst Connection
Supernovae 1998bw and its corresponding relativistically expanding radio
source are coincident with the \grb source GRB 980425. We show that of six
recent SN Ib/c for which an outburst epoch can be estimated with some
reliability, four have radio outbursts and all are correlated in time and space
with BATSE \grbs. The joint probability of all six correlations is
1.5. No such correlation exists for SN Ia and SN II. The \gr\
energy associated with the SN/GRB events is ergs if
emitted isotropically. Economy of hypotheses leads us to propose that all \grbs
are associated with supernovae and that the \grb events have a quasi-isotropic
component that cannot be observed at cosmological distances and a strongly
collimated and Doppler-boosted component that can only be seen if looking
nearly along the collimation axis. Such collimation requires a high rate of
occurrence perhaps consistent with a supernova rate. The collimated flow may be
generated by core collapse to produce rotating, magnetized neutron stars. All
core collapse events may produce such jets, but only the ones that occur in
supernovae with small or missing hydrogen envelopes, Type Ib or Ic, can
propagate into the interstellar medium and yield a visible \grb. We suggest
that asymmetries in line profiles and spectropolarimetry of SN II and SN Ib/c,
pulsar runaway velocities, soft \gr repeaters and \grbs are associated
phenomena.Comment: Submitted to ApJL on May 19, 1998. Revised on Jun 15, 199
Performance of transducers with segmented piezoelectric stacks using materials with high electromechanical coupling coefficient
Underwater acoustic transducers often include a stack of thickness polarized
piezoelectric material pieces of alternating polarity interspersed with
electrodes, bonded together and electrically connected in parallel. The stack
is normally much shorter than a quarter wavelength at the fundamental resonance
frequency, so that the mechanical behavior of the transducer is not affected by
the segmentation. When the transducer bandwidth is less than a half octave, as
has conventionally been the case, stack segmentation has no significant effect
on the mechanical behavior of the device. However, when a high coupling
coefficient material such as PMN-PT is used to achieve a wider bandwidth, the
difference between a segmented stack and a similar piezoelectric section with
electrodes only at the two ends can be significant. This paper investigates the
effects of stack segmentation on the performance of wideband underwater
acoustic transducers, particularly tonpilz transducer elements. Included is
discussion of transducer designs using single crystal piezoelectric material
with high coupling coefficient compared with more traditional PZT ceramics.Comment: 26 pages including 14 figures, one table and one appendi
Oregon Wine Board Meeting Minutes September 11, 2012
These meeting minutes list individuals in attendance and missing at the September 11, 2012 Oregon Wine Board (OWB) meeting, held via conference call. Dewey Weddington provided a marketing update focused on planning for Oregon Wine Month and the Oregon Wine Industry Symposium. The meeting also included discussion of the 2011-2012 year-end financial review and a presentation of the budget for the following year. The meeting lasted 2 hours 6 minutes, and the Board went into Executive Session after the meeting was adjourned
Sampling strategies and four-dimensional assimilation of altimetric data for ocean monitoring and prediction
Numerical experiments using simulated altimeter data were conducted in order to examine the assimilation of altimeter-derived sea surface heights into numerical ocean circulation models. A reduced-gravity, primitive equation circulation model of the Gulf of Mexico was utilized; the Gulf of Mexico was chosen because of its amenability to modeling and the ability of low vertical-mode models to reproduce the observed dynamical features of the Gulf circulation. The simulated data were obtained by flying an imaginary altimeter over the model ocean and sampling the model sea surface just as real altimeter would observe the true ocean. The data were used to initialize the numerical model and the subsequent forecast was compared to the true numerical solution. Results indicate that for a stationary, circular eddy, approximately three to four tracks (either ascending or descending) across the eddy are sufficient to ensure adequate spatial resolution
Beyond the hybrid library : libraries in a Web 2.0 world
Considers the development of social networking and the concept of Web 2.0. Looks at the implications for libraries and how traditional competences remain relevant. Explores what libraries are doing and must do to remain relevan
SGR 1806-20 Is a Set of Independent Relaxation Systems
The Soft Gamma Repeater 1806-20 produced patterns of bursts during its 1983
outburst that indicate multiple independent energy accumulation sites, each
driven by a continuous power source, with sudden, incomplete releases of the
accumulated energy. The strengths of the power sources and their durations of
activity vary over several orders of magnitude.Comment: Accepted ApJLett, 15 pages, 3 figure
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