4,313 research outputs found
The role of concurrency in an evolutionary view of programming abstractions
In this paper we examine how concurrency has been embodied in mainstream
programming languages. In particular, we rely on the evolutionary talking
borrowed from biology to discuss major historical landmarks and crucial
concepts that shaped the development of programming languages. We examine the
general development process, occasionally deepening into some language, trying
to uncover evolutionary lineages related to specific programming traits. We
mainly focus on concurrency, discussing the different abstraction levels
involved in present-day concurrent programming and emphasizing the fact that
they correspond to different levels of explanation. We then comment on the role
of theoretical research on the quest for suitable programming abstractions,
recalling the importance of changing the working framework and the way of
looking every so often. This paper is not meant to be a survey of modern
mainstream programming languages: it would be very incomplete in that sense. It
aims instead at pointing out a number of remarks and connect them under an
evolutionary perspective, in order to grasp a unifying, but not simplistic,
view of the programming languages development process
Common pulse retrieval algorithm: a fast and universal method to retrieve ultrashort pulses
We present a common pulse retrieval algorithm (COPRA) that can be used for a
broad category of ultrashort laser pulse measurement schemes including
frequency-resolved optical gating (FROG), interferometric FROG, dispersion
scan, time domain ptychography, and pulse shaper assisted techniques such as
multiphoton intrapulse interference phase scan (MIIPS). We demonstrate its
properties in comprehensive numerical tests and show that it is fast, reliable
and accurate in the presence of Gaussian noise. For FROG it outperforms
retrieval algorithms based on generalized projections and ptychography.
Furthermore, we discuss the pulse retrieval problem as a nonlinear
least-squares problem and demonstrate the importance of obtaining a
least-squares solution for noisy data. These results improve and extend the
possibilities of numerical pulse retrieval. COPRA is faster and provides more
accurate results in comparison to existing retrieval algorithms. Furthermore,
it enables full pulse retrieval from measurements for which no retrieval
algorithm was known before, e.g., MIIPS measurements
Solution of the inverse scattering problem by T-matrix completion. II. Simulations
This is Part II of the paper series on data-compatible T-matrix completion
(DCTMC), which is a method for solving nonlinear inverse problems. Part I of
the series contains theory and here we present simulations for inverse
scattering of scalar waves. The underlying mathematical model is the scalar
wave equation and the object function that is reconstructed is the medium
susceptibility. The simulations are relevant to ultrasound tomographic imaging
and seismic tomography. It is shown that DCTMC is a viable method for solving
strongly nonlinear inverse problems with large data sets. It provides not only
the overall shape of the object but the quantitative contrast, which can
correspond, for instance, to the variable speed of sound in the imaged medium.Comment: This is Part II of a paper series. Part I contains theory and is
available at arXiv:1401.3319 [math-ph]. Accepted in this form to Phys. Rev.
A solution for information management in logistics operations of modern manufacturing chains
One dominant feature of the modern manufacturing chains is the movement of goods. Manufacturing companies would remain an unprofitable investment if the supplies/logistics of raw materials, semi-finished products or final goods are not handled in an effective way. Both levels of a modern manufacturing chain-actual production and logistics-are characterized by continuous data creation at a much faster rate than they can be meaningfully analyzed and acted upon manually. Often, instant and reliable decisions need to be taken based on huge, previously inconceivable amounts of heterogeneous, contradictory or incomplete data. The paper will highlight aspects of information flows related to business process data visibility and observability in modern manufacturing networks. An information management platform developed in the framework of the EU FP7 project ADVANCE will be presented
The Inclusion of the Nature of Science and Its Elements in Recent Popular Science Writing for Adults and Young Adults
This study was conducted to examine the inclusion of nature of science (NOS) in popular science writing to determine whether it could serve supplementary resource for teaching NOS. Four groups of documents published from 2001 to 2010 were included in the analysis: Scientific American, Discover magazine, winners of the Royal Society Winton Prize for Science Books, and books listed in National Science Teacher Association\u27s (NSTA) Outstanding Science Trade Books for Students K-12.
First, computer analysis was performed to categorize passages in the selected documents based on their inclusions of NOS. Then, follow-up human analysis was conducted to assess the frequency, context, coverage, and accuracy of the inclusions of NOS within computer identified NOS passages. The results reveal that NOS was rarely addressed in selected document sets. About two to five passages explicitly addressing NOS were observed in every thousand passages. Interestingly, NOS is frequently addressed in the letters section of the two magazines. This result suggests that readers seem to be interested in the discussion of NOS-related issues. In the popular science books analyzed, NOS presentations are more likely to be aggregated in the beginning and the end of the book, rather than scattered throughout. The most commonly addressed NOS elements in the analyzed documents are science and society and the empirical aspect of science. Only three inaccurate presentations of NOS were identified in all analyzed documents.
Unfortunately, the findings suggest that popular science writing generally may not be a good resource for science educators to search for materials for teaching NOS. Since both science textbooks and popular science writing are generally disappointing in their inclusion of NOS topics, it seems to be necessary to create new science curriculum with rich features in NOS.
Contrary to the disappointing findings on the presentation of NOS in popular science writing, the text mining technique used to identify NOS presentations demonstrated exciting performance. The successful application of the text mining technique in the current study invites more applications of such technique on the analysis of other aspects of science textbooks, popular science writing, or other materials involved in science teaching and learning
Strange Hadron Spectroscopy with a Secondary KL Beam at GlueX
We propose to create a secondary beam of neutral kaons in Hall D at Jefferson
Lab to be used with the GlueX experimental setup for strange hadron
spectroscopy. A flux on the order of 3 x 10^4 KL/s will allow a broad range of
measurements to be made by improving the statistics of previous data obtained
on hydrogen targets by three orders of magnitude. Use of a deuteron target will
provide first measurements on the neutron which is {\it terra incognita}.
The experiment will measure both differential cross sections and
self-analyzed polarizations of the produced {\Lambda}, {\Sigma}, {\Xi}, and
{\Omega} hyperons using the GlueX detector at the Jefferson Lab Hall D. The
measurements will span c.m. cos{\theta} from -0.95 to 0.95 in the c.m. range
above W = 1490 MeV and up to 3500 MeV. These new GlueX data will greatly
constrain partial-wave analyses and reduce model-dependent uncertainties in the
extraction of strange resonance properties (including pole positions), and
provide a new benchmark for comparisons with QCD-inspired models and lattice
QCD calculations.
The proposed facility will also have an impact in the strange meson sector by
providing measurements of the final-state K{\pi} system from threshold up to 2
GeV invariant mass to establish and improve on the pole positions and widths of
all K*(K{\pi}) P-wave states as well as for the S-wave scalar meson
{\kappa}(800).Comment: 97 pages, 63 figures, Proposal for JLab PAC45, PR12-17-001; v3 missed
citation in Sec 9 (pg 22
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