9,852 research outputs found
Uniform Partition in Population Protocol Model Under Weak Fairness
We focus on a uniform partition problem in a population protocol model. The uniform partition problem aims to divide a population into k groups of the same size, where k is a given positive integer. In the case of k=2 (called uniform bipartition), a previous work clarified space complexity under various assumptions: 1) an initialized base station (BS) or no BS, 2) weak or global fairness, 3) designated or arbitrary initial states of agents, and 4) symmetric or asymmetric protocols, except for the setting that agents execute a protocol from arbitrary initial states under weak fairness in the model with an initialized base station. In this paper, we clarify the space complexity for this remaining setting. In this setting, we prove that P states are necessary and sufficient to realize asymmetric protocols, and that P+1 states are necessary and sufficient to realize symmetric protocols, where P is the known upper bound of the number of agents. From these results and the previous work, we have clarified the solvability of the uniform bipartition for each combination of assumptions. Additionally, we newly consider an assumption on a model of a non-initialized BS and clarify solvability and space complexity in the assumption. Moreover, the results in this paper can be applied to the case that k is an arbitrary integer (called uniform k-partition)
Theory of Nonlinear Meissner Effect in High-Tc Superconductors
We investigate the nonlinear Meissner effect microscopically. Previous
studies did not consider a certain type of interaction effect on the nonlinear
phenomena. The scattering amplitude barely appears without being renormalized
into the Fermi-liquid parameter. With this effect we can solve the outstanding
issues (the quantitative problem, the temperature and angle dependences). The
quantitative calculation is performed with use of the fluctuation-exchange
approximation on the Hubbard model. It is also shown that the perturbation
expansion on the supercurrent by the vector potential converges owing to the
nonlocal effect
Source File Set Search for Clone-and-Own Reuse Analysis
Clone-and-own approach is a natural way of source code reuse for software
developers. To assess how known bugs and security vulnerabilities of a cloned
component affect an application, developers and security analysts need to
identify an original version of the component and understand how the cloned
component is different from the original one. Although developers may record
the original version information in a version control system and/or directory
names, such information is often either unavailable or incomplete. In this
research, we propose a code search method that takes as input a set of source
files and extracts all the components including similar files from a software
ecosystem (i.e., a collection of existing versions of software packages). Our
method employs an efficient file similarity computation using b-bit minwise
hashing technique. We use an aggregated file similarity for ranking components.
To evaluate the effectiveness of this tool, we analyzed 75 cloned components in
Firefox and Android source code. The tool took about two hours to report the
original components from 10 million files in Debian GNU/Linux packages. Recall
of the top-five components in the extracted lists is 0.907, while recall of a
baseline using SHA-1 file hash is 0.773, according to the ground truth recorded
in the source code repositories.Comment: 14th International Conference on Mining Software Repositorie
Temperature-Dependence of Magnetically-Active Charge Excitations in Magnetite across the Verwey Transition
We have studied the electronic structure of bulk single crystals and
epitaxial films of magnetite FeO. Fe core-level spectra show clear
differences between hard x-ray (HAX-) and soft x-ray (SX-) photoemission
spectroscopy (PES), indicative of surface effects. The bulk-sensitive spectra
exhibit temperature ()-dependent charge excitations across the Verwey
transition at =122 K, which is missing in the surface-sensitive spectra.
An extended impurity Anderson model full-multiplet analysis reveals roles of
the three distinct Fe-species (A-Fe, B-Fe, B-Fe) below
for the Fe spectra, and its dependent evolution. The Fe
HAXPES spectra show a clear magnetic circular dichroism (MCD) in the metallic
phase of magnetized 100-nm-thick films. The model calculations also reproduce
the MCD and identify the magnetically distinct sites associated with the charge
excitations. Valence band HAXPES shows finite density of states at for
the polaronic metal with remnant order above , and a clear gap formation
below . The results indicate that the Verwey transition is driven by
changes in the strongly correlated and magnetically active B-Fe and
B-Fe electronic states, consistent with resistivity and bulk-sensitive
optical spectra.Comment: 5 pages, 4 figures Accepted in Physical Review Letter
Relaxation Dynamics of Photoinduced Changes in the Superfluid Weight of High-Tc Superconductors
In the transient state of d-wave superconductors, we investigate the temporal
variation of photoinduced changes in the superfluid weight. We derive the
formula that relates the nonlinear response function to the nonequilibrium
distribution function. The latter qunatity is obtained by solving the kinetic
equation with the electron-electron and the electron-phonon interaction
included. By numerical calculations, a nonexponential decay is found at low
temperatures in contrast to the usual exponential decay at high temperatures.
The nonexponential decay originates from the nonmonotonous temporal variation
of the nonequilibrium distribution function at low energies. The main physical
process that causes this behavior is not the recombination of quasiparticles as
previous phenomenological studies suggested, but the absorption of phonons.Comment: 18 pages, 12 figures; to be published in J. Phys. Soc. Jpn. Vol. 80,
No.
Nonlinear Optical Response Functions of Mott Insulators Based on Dynamical Mean Field Approximation
We investigate the nonlinear optical susceptibilities of Mott insulators with
the dynamical mean field approximation. The two-photon absorption (TPA) and the
third-harmonic generation (THG) spectra are calculated, and the classification
by the types of coupling to external fields shows different behavior from
conventional semiconductors. The direct transition terms are predominant both
in the TPA and THG spectra, and the importance of taking all types of
interaction with the external field into account is illustrated in connection
with the THG spectrum and dcKerr effect. The dependence of the TPA and THG
spectra on the Coulomb interaction indicate a scaling relation. We apply this
relation to the quantitative evaluation and obtain results comparable to those
of experiments.Comment: 14 pages, 12 figure
Using High-Rising Cities to Visualize Performance in Real-Time
For developers concerned with a performance drop or improvement in their
software, a profiler allows a developer to quickly search and identify
bottlenecks and leaks that consume much execution time. Non real-time profilers
analyze the history of already executed stack traces, while a real-time
profiler outputs the results concurrently with the execution of software, so
users can know the results instantaneously. However, a real-time profiler risks
providing overly large and complex outputs, which is difficult for developers
to quickly analyze. In this paper, we visualize the performance data from a
real-time profiler. We visualize program execution as a three-dimensional (3D)
city, representing the structure of the program as artifacts in a city (i.e.,
classes and packages expressed as buildings and districts) and their program
executions expressed as the fluctuating height of artifacts. Through two case
studies and using a prototype of our proposed visualization, we demonstrate how
our visualization can easily identify performance issues such as a memory leak
and compare performance changes between versions of a program. A demonstration
of the interactive features of our prototype is available at
https://youtu.be/eleVo19Hp4k.Comment: 10 pages, VISSOFT 2017, Artifact:
https://github.com/sefield/high-rising-city-artifac
Effect of Impurity Scattering on the Nonlinear Microwave Response in High-Tc Superconductors
We theoretically investigate intermodulation distortion in high-Tc
superconductors. We study the effect of nonmagnetic impurities on the real and
imaginary parts of nonlinear conductivity. The nonlinear conductivity is
proportional to the inverse of temperature owing to the dependence of the
damping effect on energy, which arises from the phase shift deviating from the
unitary limit. It is shown that the final-states interaction makes the real
part predominant over the imaginary part. These effects have not been included
in previous theories based on the two-fluid model, enabling a consistent
explanation for the experiments with the rf and dc fields
Bug or Not? Bug Report Classification Using N-Gram IDF
Previous studies have found that a significant number of bug reports are
misclassified between bugs and non-bugs, and that manually classifying bug
reports is a time-consuming task. To address this problem, we propose a bug
reports classification model with N-gram IDF, a theoretical extension of
Inverse Document Frequency (IDF) for handling words and phrases of any length.
N-gram IDF enables us to extract key terms of any length from texts, these key
terms can be used as the features to classify bug reports. We build
classification models with logistic regression and random forest using features
from N-gram IDF and topic modeling, which is widely used in various software
engineering tasks. With a publicly available dataset, our results show that our
N-gram IDF-based models have a superior performance than the topic-based models
on all of the evaluated cases. Our models show promising results and have a
potential to be extended to other software engineering tasks.Comment: 5 pages, ICSME 201
An Energy-Aware Video Streaming System for Portable Computing Devices
MDM'06 : 7th International Conference on Mobile Data Management , May 9-12, 2006 , Nara, JapanIn this demonstration, we show an energy-aware video streaming system which allows users to play back video for the specified duration within the remaining battery amount. In the system, we execute a proxy server on an intermediate node in the network. It receives the video stream from a content server, transcodes it to the videos with appropriate quality, and forwards it to a PDA or a laptop PC. Here, suitable parameter values of the video (such as picture size, frame rate and bitrate) which enable playback for the specified duration are automatically calculated on the proxy using our battery consumption model. The system also allows users to play back video segments with different qualities based on the importance specified to each video segment
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