34,269 research outputs found
Is there a prescribed parameter's space for the adiabatic geometric phase?
The Aharonov-Anandan and Berry phases are determined for the cyclic motions
of a non-relativistic charged spinless particle evolving in the superposition
of the fields produced by a Penning trap and a rotating magnetic field.
Discussion about the selection of the parameter's space and the relationship
between the Berry phase and the symmetry of the binding potential is given.Comment: 7 pages, 2 figure
A Case Study on Artefact-based RE Improvement in Practice
Most requirements engineering (RE) process improvement approaches are
solution-driven and activity-based. They focus on the assessment of the RE of a
company against an external norm of best practices. A consequence is that
practitioners often have to rely on an improvement approach that skips a
profound problem analysis and that results in an RE approach that might be
alien to the organisational needs. In recent years, we have developed an RE
improvement approach (called \emph{ArtREPI}) that guides a holistic RE
improvement against individual goals of a company putting primary attention to
the quality of the artefacts. In this paper, we aim at exploring ArtREPI's
benefits and limitations. We contribute an industrial evaluation of ArtREPI by
relying on a case study research. Our results suggest that ArtREPI is
well-suited for the establishment of an RE that reflects a specific
organisational culture but to some extent at the cost of efficiency resulting
from intensive discussions on a terminology that suits all involved
stakeholders. Our results reveal first benefits and limitations, but we can
also conclude the need of longitudinal and independent investigations for which
we herewith lay the foundation
On Evidence-based Risk Management in Requirements Engineering
Background: The sensitivity of Requirements Engineering (RE) to the context
makes it difficult to efficiently control problems therein, thus, hampering an
effective risk management devoted to allow for early corrective or even
preventive measures. Problem: There is still little empirical knowledge about
context-specific RE phenomena which would be necessary for an effective
context- sensitive risk management in RE. Goal: We propose and validate an
evidence-based approach to assess risks in RE using cross-company data about
problems, causes and effects. Research Method: We use survey data from 228
companies and build a probabilistic network that supports the forecast of
context-specific RE phenomena. We implement this approach using spreadsheets to
support a light-weight risk assessment. Results: Our results from an initial
validation in 6 companies strengthen our confidence that the approach increases
the awareness for individual risk factors in RE, and the feedback further
allows for disseminating our approach into practice.Comment: 20 pages, submitted to 10th Software Quality Days conference, 201
Comment on the numerical solutions of a new coupled MKdV system (2008 Phys. Scr. 78 045008)
In this comment we point out some wrong statements in the paper by Inc and
Cavlak, Phys. Scr. 78 (2008) 04500
Case Studies in Industry: What We Have Learnt
Case study research has become an important research methodology for
exploring phenomena in their natural contexts. Case studies have earned a
distinct role in the empirical analysis of software engineering phenomena which
are difficult to capture in isolation. Such phenomena often appear in the
context of methods and development processes for which it is difficult to run
large, controlled experiments as they usually have to reduce the scale in
several respects and, hence, are detached from the reality of industrial
software development. The other side of the medal is that the realistic
socio-economic environments where we conduct case studies -- with real-life
cases and realistic conditions -- also pose a plethora of practical challenges
to planning and conducting case studies. In this experience report, we discuss
such practical challenges and the lessons we learnt in conducting case studies
in industry. Our goal is to help especially inexperienced researchers facing
their first case studies in industry by increasing their awareness for typical
obstacles they might face and practical ways to deal with those obstacles.Comment: Proceedings of the 4th International Workshop on Conducting Empirical
Studies in Industry, co-located with ICSE, 201
Competition between quantum spin tunneling and Kondo effect
Quantum spin tunneling (QST) and Kondo effect are two very different quantum
phenomena that produce the same effect on quantized spins, namely, the
quenching of their magnetization. However, the nature of this quenching is very
different so that QST and Kondo effects compete with each other. Importantly,
both QST and Kondo produce very characteristic features in the spectral
function that can be measured by means of single spin scanning tunneling
spectroscopy that makes it possible to probe the crossover from one regime to
the other. We model this crossover, and the resulting changes in transport,
using a non-perturbative treatment of a generalized Anderson model including
magnetic anisotropy that leads to quantum spin tunneling. We predict that, at
zero magnetic field, integer spins can feature a split-Kondo peak driven by
quantum spin tunneling.Comment: 5 pages, 3 figures; accepted in EPJB; replaced with revised
manuscrip
Naming the Pain in Requirements Engineering: A Design for a Global Family of Surveys and First Results from Germany
For many years, we have observed industry struggling in defining a high
quality requirements engineering (RE) and researchers trying to understand
industrial expectations and problems. Although we are investigating the
discipline with a plethora of empirical studies, they still do not allow for
empirical generalisations. To lay an empirical and externally valid foundation
about the state of the practice in RE, we aim at a series of open and
reproducible surveys that allow us to steer future research in a problem-driven
manner. We designed a globally distributed family of surveys in joint
collaborations with different researchers and completed the first run in
Germany. The instrument is based on a theory in the form of a set of hypotheses
inferred from our experiences and available studies. We test each hypothesis in
our theory and identify further candidates to extend the theory by correlation
and Grounded Theory analysis. In this article, we report on the design of the
family of surveys, its underlying theory, and the full results obtained from
Germany with participants from 58 companies. The results reveal, for example, a
tendency to improve RE via internally defined qualitative methods rather than
relying on normative approaches like CMMI. We also discovered various RE
problems that are statistically significant in practice. For instance, we could
corroborate communication flaws or moving targets as problems in practice. Our
results are not yet fully representative but already give first insights into
current practices and problems in RE, and they allow us to draw lessons learnt
for future replications. Our results obtained from this first run in Germany
make us confident that the survey design and instrument are well-suited to be
replicated and, thereby, to create a generalisable empirical basis of RE in
practice
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