786,888 research outputs found
Third Divergence: Representations and Reflections
This paper presents an exploration of the process of developing a music composition through various layers of interaction with ideas through the abstract and the real. The composition is the most significant component of the project as a whole, and this paper regards itself as a sort of artist\u27s journal developed during creation of the composition, making some attempt to show the process of improvising through the project. The project as a whole explores the various conceptualizations of the idea, of the relationship between the abstract and the real, and representations of a work that cannot be fully known. The composition itself represents the whole project through the interaction of two central ideas merging towards a circle of relation. Particular attention is given to the dynamic of composition and improvisation, and the role of improvisation in the creation of new work
Chemical Distribution of the Dynamical Ejecta in the Neutron Star Merger GW170817
GW170817 and its associated electromagnetic counterpart AT2017gfo continue to
be a treasure trove as observations and modeling continue. Recent precision
astrometry of AT2017gfo with the Hubble Space Telescope combined with previous
constraints from Very Long Baseline Interferometry (VLBI) constraints narrowed
down the inclination angle to 19-25 deg (90\% confidence). This paper explores
how the inclusion of precise inclination information can reveal new insights
about the ejecta properties, in particular, about the composition of the
dynamical ejecta of AT2017gfo. Our analysis relies on updated kilonova
modeling, which includes state-of-the-art heating rates, thermalization
efficiencies, and opacities and is parameterized by , the
average electron fraction of the dynamical ejecta component. Using this model,
we incorporate the latest inclination angle constraint of AT2017gfo into a
light curve fitting framework to derive updated parameter estimates. Our
results suggest that the viewing angle of the observer is pointed towards the
lanthanide-poor (), squeezed polar dynamical ejecta
component, which can explain the early blue emission observed in the light
curve of AT2017gfo. In contrast to a recent claim of spherical ejecta powering
AT2017gfo, our study indicates that the composition of the dynamical ejecta has
a strong angular dependence, with a lanthanide-rich (), tidal component distributed around the merger plane with
a half-opening angle of . The inclination angle constraint reduces
from to , with values enabling the robust production of -process elements up
to the peak in the tidal dynamical ejecta.Comment: 8 pages, 6 figure
A conceptual architecture for semantic web services development and deployment
Several extensions of the Web Services Framework (WSF) have been proposed. The combination with Semantic Web technologies introduces a notion of semantics, which can enhance scalability through automation. Service composition to processes is an equally important issue. Ontology technology – the core of the Semantic Web – can be the central building block of an extension endeavour. We present a conceptual architecture for ontology-based Web service development and deployment. The development of service-based software systems within the WSF is gaining increasing importance. We show how ontologies can integrate models, languages, infrastructure, and activities within this architecture to support reuse and composition of semantic Web services
Generalised model for heteroazeotropic batch distillation with variable decanter hold-up
A general model of batch heteroazeotropic distillation is proposed. Both liquid phases present in the decanter can be refluxed or withdrawn as distillate, their hold-up can be increased, decreased or kept constant, as well. By assuming maximal separation, that is, that the composition of the condensate always equals to that of the heteroazeotrope, the still path equation was derived. The still path directions are determined for all the 16 possible operational policies. It is possible to steer the still path in a desired direction by changing the operational parameters, which allows the recovery of a pure component in the still. The still path directions are validated by rigorous simulations for three policies not published yet using the mixture water – formaldehyde – propyl formate. From the 16 operational policies, 11 can be considered as useful in practice. To demonstrate the advantage of using a non-traditional policy, the separation of the mixture aniline – ethylene glycol – water was investigated, as well. By using a non-traditional operational policy with hold-up reduction in the decanter a higher purity of ethylene glycol was obtained in the still
Towards Formal Interaction-Based Models of Grid Computing Infrastructures
Grid computing (GC) systems are large-scale virtual machines, built upon a
massive pool of resources (processing time, storage, software) that often span
multiple distributed domains. Concurrent users interact with the grid by adding
new tasks; the grid is expected to assign resources to tasks in a fair,
trustworthy way. These distinctive features of GC systems make their
specification and verification a challenging issue. Although prior works have
proposed formal approaches to the specification of GC systems, a precise
account of the interaction model which underlies resource sharing has not been
yet proposed. In this paper, we describe ongoing work aimed at filling in this
gap. Our approach relies on (higher-order) process calculi: these core
languages for concurrency offer a compositional framework in which GC systems
can be precisely described and potentially reasoned about.Comment: In Proceedings DCM 2013, arXiv:1403.768
Modal logics for reasoning about object-based component composition
Component-oriented development of software supports the adaptability and maintainability of large systems, in particular if requirements change over time and parts of a system have to be modified or replaced. The software architecture in such systems can be described by components
and their composition. In order to describe larger architectures, the composition concept becomes crucial. We will present a formal framework for component composition for object-based software development. The deployment of modal logics for defining components and component composition will allow us to reason about and prove properties of components and compositions
Term-based composition of security protocols
In the context of security protocol parallel composition, where messages
belonging to different protocols can intersect each other, we introduce a new
paradigm: term-based composition (i.e. the composition of message components
also known as terms). First, we create a protocol specification model by
extending the original strand spaces. Then, we provide a term composition
algorithm based on which new terms can be constructed. To ensure that security
properties are maintained, we introduce the concept of term connections to
express the existing connections between terms and encryption contexts. We
illustrate the proposed composition process by using two existing protocols.Comment: 2008 IEEE International Conference on Automation, Quality and
Testing, Robotics, Cluj-Napoca, Romania, May 2008, pp. 233-238, ISBN
978-1-4244-2576-
Kinetic pathways of multi-phase surfactant systems
The relaxation following a temperature quench of two-phase (lamellar and
sponge phase) and three-phase (lamellar, sponge and micellar phase) samples,
has been studied in an SDS/octanol/brine system. In the three-phase case we
have observed samples that are initially mainly sponge phase with lamellar and
micellar phase on the top and bottom respectively. Upon decreasing temperature
most of the volume of the sponge phase is replaced by lamellar phase. During
the equilibriation we have observed three regimes of behaviour within the
sponge phase: (i) disruption in the sponge texture, then (ii) after the sponge
phase homogenises there is a lamellar nucleation regime and finally (iii) a
bizarre plume connects the lamellar phase with the micellar phase. The
relaxation of the two-phase sample proceeds instead in two stages. First
lamellar drops nucleate in the sponge phase forming a onion `gel' structure.
Over time the lamellar structure compacts while equilibriating into a two phase
lamellar/sponge phase sample. We offer possible explanatioins for some of these
observations in the context of a general theory for phase kinetics in systems
with one fast and one slow variable.Comment: 1 textfile, 20 figures (jpg), to appear in PR
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