2,015 research outputs found
An Analysis of the Search Spaces for Generate and Validate Patch Generation Systems
We present the first systematic analysis of the characteristics of patch
search spaces for automatic patch generation systems. We analyze the search
spaces of two current state-of-the-art systems, SPR and Prophet, with 16
different search space configurations. Our results are derived from an analysis
of 1104 different search spaces and 768 patch generation executions. Together
these experiments consumed over 9000 hours of CPU time on Amazon EC2.
The analysis shows that 1) correct patches are sparse in the search spaces
(typically at most one correct patch per search space per defect), 2) incorrect
patches that nevertheless pass all of the test cases in the validation test
suite are typically orders of magnitude more abundant, and 3) leveraging
information other than the test suite is therefore critical for enabling the
system to successfully isolate correct patches.
We also characterize a key tradeoff in the structure of the search spaces.
Larger and richer search spaces that contain correct patches for more defects
can actually cause systems to find fewer, not more, correct patches. We
identify two reasons for this phenomenon: 1) increased validation times because
of the presence of more candidate patches and 2) more incorrect patches that
pass the test suite and block the discovery of correct patches. These
fundamental properties, which are all characterized for the first time in this
paper, help explain why past systems often fail to generate correct patches and
help identify challenges, opportunities, and productive future directions for
the field
Neutron ages computed from experimental activation data
Computer program reduces time manually required to compute neutron age and to provide definite plan of procedural choices. Program allows convenient comparison of several fitting and error analysis procedures. Program code provides for error estimation of various integration options
Implementation experiences of NASTRAN on CDC CYBER 74 SCOPE 3.4 operating system
The implementation of the NASTRAN system on the CDC CYBER 74 SCOPE 3.4 Operating System is described. The flexibility of the NASTRAN system made it possible to accomplish the change with no major problems. Various sizes of benchmark and test problems, ranging from two hours to less than one minute CP time were run on the CDC CYBER SCOPE 3.3, Univac EXEC-8, and CDC CYBER SCOPE 3.4. The NASTRAN installation deck is provided
Millimeter-wave antenna system
Parabolic reflectors fabricated from Carbon Fiber Reinforced Plastic (CFRP) composite material will not distort their shape by more than 3 percent of millimeter wavelength, despite large temperature differences on reflector surfaces. CFRP has zero thermal expansion. It is derived from charred polyacrylonitrite plastic filaments that are combined with epoxy resin
First direct limit on the 334 keV resonance strength in the Ne({\alpha},{\gamma})Mg reaction
In stars, the fusion of Ne and He may produce either Mg,
with the emission of a neutron, or Mg and a ray. At high
temperature, the () channel dominates, while at low temperature, it
is energetically hampered. The rate of its competitor, the
Ne(,)Mg reaction, and, hence, the minimum
temperature for the () dominance, are controlled by many nuclear
resonances. The strengths of these resonances have hitherto been studied only
indirectly. The present work aims to directly measure the total strength of the
resonance at _{r}334keV (corresponding to
_{x}10949keV in Mg). The data reported here have been
obtained using high intensity He beam from the INFN LUNA 400 kV
underground accelerator, a windowless, recirculating, 99.9% isotopically
enriched Ne gas target, and a 4 bismuth germanate summing
-ray detector. The ultra-low background rate of less than 0.5
counts/day was determined using 67 days of no-beam data and 7 days of
He beam on an inert argon target. The new high-sensitivity setup
allowed to determine the first direct upper limit of 4.010
eV (at 90% confidence level) for the resonance strength. Finally, the
sensitivity of this setup paves the way to study further
Ne(,)Mg resonances at higher energy.Comment: Submitted to Eur. Phys. J.
Trigonometric identities, angular Schr\"{o}dinger equations and a new family of solvable models
Angular parts of certain solvable models are studied. We find that an
extension of this class may be based on suitable trigonometric identities. The
new exactly solvable Hamiltonians are shown to describe interesting two- and
three-particle systems of the generalized Calogero, Wolfes and
Winternitz-Smorodinsky types.Comment: to appear in Phys. Lett.
A Computational Model for Temperature Monitoring During Human Liver Treatment by Nd:YaG Laser Interstitial Thermal Therapy (LITT)
Describing heat transfer in biological organs is absolutely challenging because it is involved with many complex phenomena. Therefore, understanding the optical and thermal properties of living system during external irradiation sources such as laser interstitial thermal therapy (LITT) are too important for therapeutic purposes, especially for hyperthermia treatments. The purpose of this study was to determine a proper laser power and irradiation time for LITT applicator to irradiate liver tissue during hyperthermia treatment. For this aim, bioheat equation in one-dimensional spherical coordinate is solved by Green function method to simulate temperature distribution and rate of damage around irradiated target and how thermal and optical properties such as laser power, laser exposure time, and blood perfusion rate affect the rate of temperature distribution. Guiding equations according to the suggested boundary conditions are written and solved by MATLAB software. The outcomes show that increasing laser exposure time and power increase the temperature, especially at the nearest distance from the center of diffusion. Accordingly, a decrease in blood perfusion rate leads to decrease temperature distribution. The findings show that the model is useful to help the physicians to monitor the amount of heat diffusion by laser power during the treatment to protect healthy cells
Entanglement and the Quantum Brachistochrone Problem
Entanglement is closely related to some fundamental features of the dynamics
of composite quantum systems: quantum entanglement enhances the "speed" of
evolution of certain quantum states, as measured by the time required to reach
an orthogonal state. The concept of "speed" of quantum evolution constitutes an
important ingredient in any attempt to determine the fundamental limits that
basic physical laws impose on how fast a physical system can process or
transmit information. Here we explore the relationship between entanglement and
the speed of quantum evolution in the context of the quantum brachistochrone
problem. Given an initial and a final state of a composite system we consider
the amount of entanglement associated with the brachistochrone evolution
between those states, showing that entanglement is an essential resource to
achieve the alluded time-optimal quantum evolution.Comment: 6 pages, 3 figures. Corrected typos in Eqs. 1 and
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