11,465 research outputs found
Enabling Multi-Stakeholder Cooperative Modelling in Automotive Software Development and Implications for Model Driven Software Development
One of the motivations for a model driven approach to software development is to increase the involvement for a range of stakeholders in the requirements phases. This inevitably leads to a greater diversity of roles being involved in the production of models, and one of the issues with such diversity is that of providing models which are both accessible and appropriate for the phenomena being modelled. Indeed, such accessibility issues are a clear focus of this workshop.
However, a related issue when producing models across multiple parties,often at dierent sites, or even dierent organisations is the management of such model artefacts. In particular, different parties may wish
to experiment with model choices. For example, this idea of prototypingprocesses by experimenting with variants of models is one which has been used for many years by business process modellers, in order to highlight
the impact of change, and thus improve alignment of process and supporting software specications. The problem often occurs when such variants needed to be merged, for example, to be used within a shared repository.
This papers reports upon experiences and ndings of this merging problem as evaluated at Bosch Automotive. At Bosch we have dierent sites where modellers will make changes to shared models, and these models will subsequently require merging into a common repository. Currently,
this work has concentrated on one type of diagram, the class diagram. However, it seems clear that the issue of how best to merge models where collaborative multi-party working takes places is one which has a significant
potential impact upon the entire model driven process, and, given the diversity of stakeholders, could be particularly problematic for the requirements phase. In fact, class diagrams can also be used for information
or data models created in the system analysis step. Hence, we believe that the lessons learned from this work will be valuable in tackling the realities of a commercially viable model driven process
Trigonometric R Matrices related to `Dilute' Birman--Wenzl--Murakami Algebra
Explicit expressions for three series of matrices which are related to a
``dilute'' generalisation of the Birman--Wenzl--Murakami are presented. Of
those, one series is equivalent to the quantum matrices of the
generalised Toda systems whereas the remaining two series
appear to be new.Comment: 5 page
On Flux Quantization in F-Theory II: Unitary and Symplectic Gauge Groups
We study the quantization of the M-theory G-flux on elliptically fibered
Calabi-Yau fourfolds with singularities giving rise to unitary and symplectic
gauge groups. We seek and find its relation to the Freed-Witten quantization of
worldvolume fluxes on 7-branes in type IIB orientifold compactifications on
Calabi-Yau threefolds. By explicitly constructing the appropriate four-cycles
on which to calculate the periods of the second Chern class of the fourfolds,
we find that there is a half-integral shift in the quantization of G-flux
whenever the corresponding dual 7-brane is wrapped on a non-spin submanifold.
This correspondence of quantizations holds for all unitary and symplectic gauge
groups, except for SU(3), which behaves mysteriously. We also perform our
analysis in the case where, in addition to the aforementioned gauge groups,
there is also a 'flavor' U(1)-gauge group.Comment: 33 pages, 4 figure
Efficient creation of molecules from a cesium Bose-Einstein condensate
We report a new scheme to create weakly bound Cs molecules from an atomic
Bose-Einstein condensate. The method is based on switching the magnetic field
to a narrow Feshbach resonance and yields a high atom-molecule conversion
efficiency of more than 30%, a factor of three higher than obtained with
conventional magnetic-field ramps. The Cs molecules are created in a single
-wave rotational quantum state. The observed dependence of the conversion
efficiency on the magnetic field and atom density shows scattering processes
beyond two-body coupling to occur in the vicinity of the Feshbach resonance.Comment: 7 pages, 4 figures, submitted to Europhysics Letter
Anomaly Cancelation in Field Theory and F-theory on a Circle
We study the manifestation of local gauge anomalies of four- and
six-dimensional field theories in the lower-dimensional Kaluza-Klein theory
obtained after circle compactification. We identify a convenient set of
transformations acting on the whole tower of massless and massive states and
investigate their action on the low-energy effective theories in the Coulomb
branch. The maps employ higher-dimensional large gauge transformations and
precisely yield the anomaly cancelation conditions when acting on the one-loop
induced Chern-Simons terms in the three- and five-dimensional effective theory.
The arising symmetries are argued to play a key role in the study of the
M-theory to F-theory limit on Calabi-Yau manifolds. For example, using the fact
that all fully resolved F-theory geometries inducing multiple Abelian gauge
groups or non-Abelian groups admit a certain set of symmetries, we are able to
generally show the cancelation of pure Abelian or pure non-Abelian anomalies in
these models.Comment: 48 pages, 2 figures; v2: typos corrected, comments on circle fluxes
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The Statistical Discrepancy
The statistical discrepancy is equal to gross domestic product less gross domestic income. These two measures are, in principle, the same. The difference reflects less than perfect source data. The paper finds few components that statistically significantly explain the discrepancy in the last 35 years or in major subperiods, and their explanatory power is weak. The paper also finds that comprehensive benchmark revisions of the NIPAs appear to result in reductions in the explanatory power of the components that are likely to be due to reductions in measurement errors.
Design and fabrication of an autonomous rendezvous and docking sensor using off-the-shelf hardware
NASA Marshall Space Flight Center (MSFC) has developed and tested an engineering model of an automated rendezvous and docking sensor system composed of a video camera ringed with laser diodes at two wavelengths and a standard remote manipulator system target that has been modified with retro-reflective tape and 830 and 780 mm optical filters. TRW has provided additional engineering analysis, design, and manufacturing support, resulting in a robust, low cost, automated rendezvous and docking sensor design. We have addressed the issue of space qualification using off-the-shelf hardware components. We have also addressed the performance problems of increased signal to noise ratio, increased range, increased frame rate, graceful degradation through component redundancy, and improved range calibration. Next year, we will build a breadboard of this sensor. The phenomenology of the background scene of a target vehicle as viewed against earth and space backgrounds under various lighting conditions will be simulated using the TRW Dynamic Scene Generator Facility (DSGF). Solar illumination angles of the target vehicle and candidate docking target ranging from eclipse to full sun will be explored. The sensor will be transportable for testing at the MSFC Flight Robotics Laboratory (EB24) using the Dynamic Overhead Telerobotic Simulator (DOTS)
Quantum information processing with single photons and atomic ensembles in microwave coplanar waveguide resonators
We show that pairs of atoms optically excited to the Rydberg states can
strongly interact with each other via effective long-range dipole-dipole or van
der Waals interactions mediated by their non-resonant coupling to a common
microwave field mode of a superconducting coplanar waveguide cavity. These
cavity mediated interactions can be employed to generate single photons and to
realize in a scalable configuration a universal phase gate between pairs of
single photon pulses propagating or stored in atomic ensembles in the regime of
electromagnetically induced transparency
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