An Exploratory Study of Forces and Frictions affecting Large-Scale Model-Driven Development

In this paper, we investigate model-driven engineering, reporting on an exploratory case-study conducted at a large automotive company. The study consisted of interviews with 20 engineers and managers working in different roles. We found that, in the context of a large organization, contextual forces dominate the cognitive issues of using model-driven technology. The four forces we identified that are likely independent of the particular abstractions chosen as the basis of software development are the need for diffing in software product lines, the needs for problem-specific languages and types, the need for live modeling in exploratory activities, and the need for point-to-point traceability between artifacts. We also identified triggers of accidental complexity, which we refer to as points of friction introduced by languages and tools. Examples of the friction points identified are insufficient support for model diffing, point-to-point traceability, and model changes at runtime.Comment: To appear in proceedings of MODELS 2012, LNCS Springe

Search for Lepton Flavour Violation in the Decay tau -> mu gamma

A search for the lepton flavour violating decay tau -> mu gamma has been performed using 221.4/fb of data collected at an e+e- centre-of-mass energy of 10.58 GeV with the BABAR detector at the PEP-II storage ring. The search has an efficiency of (7.45+/-0.65)% for an expected background level of 6.2+/-0.5 events. In the final sample 4 candidate events are selected. As there is no evidence for a signal in this data, for this preliminary result we set an upper limit of BR(tau -> mu gamma) < 9 x 10^-8 at 90%CL using the method of Feldman and Cousins.Comment: 7 pages, 3 encapsulated postscript figures, uses espcrc2.st

Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

In-duct beamforming techniques have been developed for locating broadband noise sources on a low-speed fan and quantifying the acoustic power in the inlet and aft fan ducts. The NASA Glenn Research Center's Advanced Noise Control Fan was used as a test bed. Several of the blades were modified to provide a broadband source to evaluate the efficacy of the in-duct beamforming technique. Phased arrays consisting of rings and line arrays of microphones were employed. For the imaging, the data were mathematically resampled in the frame of reference of the rotating fan. For both the imaging and power measurement steps, array steering vectors were computed using annular duct modal expansions, selected subsets of the cross spectral matrix elements were used, and the DAMAS and CLEAN-SC deconvolution algorithms were applied

GULF STREAM MEANDERS OFF NORTH CAROLINA DURING WINTER AND SUMMER 1979.

Meanders produced most of the subtidal variability in the Gulf Stream off North Carolina during 1979. Recording instruments were moored in the lower half of the water column over the 200-m and 400-m isobaths for two periods of 4 months, one in the late winter and one in the late summer. In both seasons, the middepth current speed typically fluctuated between minus 50 cm s** minus **1 and plus 100 cm s** minus **1 about a 30 cm s** minus **1 downstream mean. The velocity, temperature, and salinity fluctuations had a prominent weekly time scale in the winter, caused by the meandering stream. In the summer the weekly time scale was less prominent within a generally energetic 3- to 10-day period band. In both seasons, the meandering currents were nearly in phase vertically, and the meanders propagated downstream at approximationly 40 km d** minus **1. Shallow, in-shore filaments of warm water, separated from the main stream by bands of cooler surface water, are often extruded from the Gulf Stream front during the shoreward-most phase (crest) of meanders

Gulf Stream meanders along the Continental Margin from the Florida Straits to Cape Hatteras

A rapid increase in the magnitude of Gulf Stream meanders downstream of a seaward deflection of the Stream off Charleston, South Carolina, has been indicated by an analysis of the shoreward surface thermal front of the Stream. The sixty four cases examined show that lateral movements of the Stream from Charleston to Cape Hatteras may be as great as 40 km from the mean, whereas upstream of Charleston the movements are generally less than 15 km in amplitude. This difference points to the importance of the deflection of the Stream by a bottom feature off Charleston in producing Gulf Stream meanders

The High Magnetic Field Phase Diagram of a Quasi-One Dimensional Metal

We present a unique high magnetic field phase of the quasi-one dimensional organic conductor (TMTSF)$_2$ClO$_4$. This phase, termed "Q-ClO$_4$", is obtained by rapid thermal quenching to avoid ordering of the ClO$_4$ anion. The magnetic field dependent phase of Q-ClO$_4$ is distinctly different from that in the extensively studied annealed material. Q-ClO$_4$ exhibits a spin density wave (SDW) transition at $\approx$ 5 K which is strongly magnetic field dependent. This dependence is well described by the theoretical treatment of Bjelis and Maki. We show that Q-ClO$_4$ provides a new B-T phase diagram in the hierarchy of low-dimensional organic metals (one-dimensional towards two-dimensional), and describe the temperature dependence of the of the quantum oscillations observed in the SDW phase.Comment: 10 pages, 4 figures, preprin

Preparation of one 87Rb and one 133Cs atom in a single optical tweezer

We report the preparation of exactly one 87Rb atom and one133Cs atom in the same optical tweezer as the essential first step towards the construction of a tweezer array of individually trapped 87Rb133Cs molecules. Through careful selection of the tweezer wavelengths, we show how to engineer species-selective trapping potentials suitable for high-fidelity preparation of Rb + Cs atom pairs. Using a wavelength of 814 nm to trap Rb and 938 nm to trap Cs, we achieve loading probabilities of 0.508(6) for Rb and 0.547(6) for Cs using standard red-detuned molasses cooling. Loading the traps sequentially yields exactly one Rb and one Cs atom in 28.4(6) % of experimental runs. Using a combination of an acousto-optic deflector and a piezo-controlled mirror to control the relative position of the tweezers, we merge the two tweezers, retaining the atom pair with a probability of 0.99(+0.01)(−0.02).We use this capability to study hyperfine-state-dependent collisions of Rb and Cs in the combined tweezer and compare the measured two-body loss rates with coupled-channel quantum scattering calculations