7,900 research outputs found
The enhanced Software Life Cyle Support Environment (ProSLCSE): Automation for enterprise and process modeling
In this paper, we have introduced a comprehensive method for enterprise modeling that addresses the three important aspects of how an organization goes about its business. FirstEP includes infrastructure modeling, information modeling, and process modeling notations that are intended to be easy to learn and use. The notations stress the use of straightforward visual languages that are intuitive, syntactically simple, and semantically rich. ProSLCSE will be developed with automated tools and services to facilitate enterprise modeling and process enactment. In the spirit of FirstEP, ProSLCSE tools will also be seductively easy to use. Achieving fully managed, optimized software development and support processes will be long and arduous for most software organizations, and many serious problems will have to be solved along the way. ProSLCSE will provide the ability to document, communicate, and modify existing processes, which is the necessary first step
Spin-flop and antiferromagnetic phases of the ferromagnetic half-twist ladder compounds Ba3Cu3In4O12 and Ba3Cu3Sc4O12
The title compounds have dominant ferromagnetic (FM) exchange interactions
within one-dimensional (1D) half-twist ladders of s =1/2 Cu2^{+} ions and
antiferromagnetic(AFM) interactions between ladders, leading to ordered 3D
phases at temperatures below 20K. Here we show that a microscopic 1D model of
the paramagnetic (PM) phase combined with a phenomenological model based on
sublattice magnetization describes the observed temperature and field dependent
magnetism. The model identifies AFM, spin-flop (SF) and PM phases whose
boundaries have sharp features in the experimental magnetization M(T,H) and
specific heat CP(T,H). Exact diagonalization (ED) of the 1D model, possible for
24 spins due to special structural features of half-twist ladders, yields the
magnetization and spin susceptibility of the PM phase. AFM interactions between
ladders are included at the mean-field level using the field, HAF, obtained
from modeling the ordered phases. Isotropic exchange J1 = -135K and g-tensor g
= 2.1 within ladders, plus exchange and anisotropy fields HAF and HA, describe
the ordered phases, and are almost quantitative for the PM phase.Comment: 21 pages,9 figures and accepted in Journal of Physics: Condensed
Matte
Non-contact ultrasonic detection of angled surface defects
Non-destructive testing is an important technique, and improvements are constantly needed. Surface defects in metals are not necessarily confined to orientations normal to the sample surface; however, much of the previous work investigating the interaction of ultrasonic surface waves with surface-breaking defects has assumed cracks inclined at 90° to the surface. This paper explores the interaction of Rayleigh waves with cracks which have a wide range of angles and depths relative to the surface, using a non-contact laser generation and detection system. Additional insight is acquired using a 3D model generated using finite element method software. A clear variation of the reflection and transmission coefficients with both crack angle and length is found, in both the out-of-plane and in-plane components. The 3D model is further used to understand the contributions of different wavemodes to B-Scans produced when scanning a sample, to enable understanding of the reflection and transmission behaviour, and help identify angled defects. Knowledge of these effects is essential to correctly gauge the severity of surface cracking
The Opportunities and Challenges of the Changing Public Services Landscape for the Third Sector in Scotland
Scanning laser source and scanning laser detection techniques for different surface crack geometries
Standard test samples typically contain simulated defects such as slots machined normal to the surface. However, real defects will not always propagate in this manner; for example, rolling contact fatigue on rails propagates at around 25º to the surface, and corrosion cracking can grow in a branched manner. Therefore, there is a need to understand how ultrasonic surface waves interact with different crack geometries. We present measurements of machined slots inclined at an angle to the surface normal, or with simple branched geometries, using laser ultrasound. Recently, Rayleigh wave enhancements observed when using the scanning laser source technique, where a generation laser is scanned along a sample, have been highlighted for their potential in detecting surface cracks. We show that the enhancement measured with laser detector scanning can give a more significant enhancement when different crack geometries are considered. We discuss the behaviour of an incident Rayleigh wave in the region of an angled defect, and consider mode-conversions which lead to a very large enhancement when the detector is close to the opening of a shallow defect. This process could be used in characterising defects, as well as being an excellent fingerprint of their presence
Anomalous quantum reflection of Bose-Einstein condensates from a silicon surface: the role of dynamical excitations
We investigate the effect of inter-atomic interactions on the
quantum-mechanical reflection of Bose-Einstein condensates from regions of
rapid potential variation. The reflection process depends critically on the
density and incident velocity of the condensate. For low densities and high
velocities, the atom cloud has almost the same form before and after
reflection. Conversely, at high densities and low velocities, the reflection
process generates solitons and vortex rings that fragment the condensate. We
show that this fragmentation can explain the anomalously low reflection
probabilities recently measured for low-velocity condensates incident on a
silicon surface.Comment: 5 figures, 5 pages, references correcte
Space shuttle external tank performance improvements: The challenge
The external tank (ET) has been actively involved in performance improvements since the inception of the space shuttle program, primarily by weight savings. Weight savings were realized on the first block of flight articles (standard weight tank). With a need for further performance improvements, the ET Program Office was requested to develop a program to reduce tank weight an additional 6000 lb and schedule delivery of the first lightweight ET (LWT) for June 1982. The weight savings program was accomplished by: (1) a unique approach to use of factors of safety; (2) design optimization; and (3) redesign of structures with large margins of safety which resulted in an actual weight savings of 7294 lb. Additional studies have identified further weight savings which are to be implemented at appropriate times in production flow. Examples are an improved thermal protection system for the LH2 tank aft dome and reduction of slosh baffles in the LO2 tank based on flight data. All performance improvements were compared and selected based on non-recurring and recurring cost and technical risk
Strong lens search in the ESO public Survey KiDS
We have started a systematic search of strong lens candidates in the ESO
public survey KiDS based on the visual inspection of massive galaxies in the
redshift range . As a pilot program we have inspected 100 sq. deg.,
which overlap with SDSS and where there are known lenses to use as a control
sample. Taking advantage of the superb image quality of VST/OmegaCAM, the
colour information and accurate model subtracted images, we have found 18 new
lens candidates, for which spectroscopic confirmation will be needed to confirm
their lensing nature and study the mass profile of the lensing galaxies.Comment: 4 pages, 1 figure, to appear on the refereed Proceeding of the "The
Universe of Digital Sky Surveys" conference held at the INAF--OAC, Naples, on
25th-28th november 2014, to be published on Astrophysics and Space Science
Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodic
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