21,725 research outputs found
Expressiveness of Generic Process Shape Types
Shape types are a general concept of process types which work for many
process calculi. We extend the previously published Poly* system of shape types
to support name restriction. We evaluate the expressiveness of the extended
system by showing that shape types are more expressive than an implicitly typed
pi-calculus and an explicitly typed Mobile Ambients. We demonstrate that the
extended system makes it easier to enjoy advantages of shape types which
include polymorphism, principal typings, and a type inference implementation.Comment: Submitted to Trustworthy Global Computing (TGC) 2010
Temporal markers of prosodic boundaries in children's speech production
It is often thought that the ability to use prosodic features accurately is mastered in early childhood. However, research to date has produced conflicting evidence, notably about the development of children's ability to mark prosodic boundaries. This paper investigates (i) whether, by the age of eight, children use temporal boundary features in their speech in a systematic way, and (ii) to what extent adult listeners are able to interpret their production accurately and unambiguously. The material consists of minimal pairs of utterances: one utterance includes a compound noun, in which there is no prosodic boundary after the first noun, e.g. ‘coffee-cake and tea’, while the other utterance includes simple nouns, separated by a prosodic boundary, e.g. ‘coffee, cake and tea’. Ten eight-year-old children took part, and their productions were rated by 23 adult listeners. Two phonetic exponents of prosodic boundaries were analysed: pause duration and phrase-final lengthening. The results suggest that, at the age of 8, there is considerable variability among children in their ability to mark phrase boundaries of the kind analysed in the experiment, with some children failing to differentiate between the members of the minimal pairs reliably. The differences between the children in their use of boundary features were reflected in the adults' perceptual judgements. Both temporal cues to prosodic boundaries significantly affected the perceptual ratings, with pause being a more salient determinant of ratings than phrase-final lengthening
Realisability Semantics for Intersection Types and Expansion Variables
Expansion was invented at the end of the 1970s for calculating principal
typings for -terms in type systems with intersection types. Expansion
variables (E-variables) were invented at the end of the 1990s to simplify and
help mechanise expansion. Recently, E-variables have been further simplified
and generalised to also allow calculating type operators other than just
intersection. There has been much work on denotational semantics for type
systems with intersection types, but none whatsoever before now on type systems
with E-variables. Building a semantics for E-variables turns out to be
challenging. To simplify the problem, we consider only E-variables, and not the
corresponding operation of expansion. We develop a realisability semantics
where each use of an E-variable in a type corresponds to an independent degree
at which evaluation occurs in the -term that is assigned the type. In
the -term being evaluated, the only interaction possible between
portions at different degrees is that higher degree portions can be passed
around but never applied to lower degree portions. We apply this semantics to
two intersection type systems. We show these systems are sound, that
completeness does not hold for the first system, and completeness holds for the
second system when only one E-variable is allowed (although it can be used many
times and nested). As far as we know, this is the first study of a denotational
semantics of intersection type systems with E-variables (using realisability or
any other approach)
Wind-tunnel investigation of the aerodynamic pressures on the Apollo command module configuration
Wind tunnel study of aerodynamic pressures on Apollo command module configuratio
Phonon-induced linewidths of graphene electronic states
The linewidths of the electronic bands originating from the electron-phonon
coupling in graphene are analyzed based on model tight-binding calculations and
experimental angle-resolved photoemission spectroscopy (ARPES) data. Our
calculations confirm the prediction that the high-energy optical phonons
provide the most essential contribution to the phonon-induced linewidth of the
two upper occupied bands near the -point. For larger
binding energies of these bands, as well as for the band, we find
evidence for a substantial lifetime broadening from interband scattering and , respectively, driven by the
out-of-plane ZA acoustic phonons. The essential features of the calculated
band linewidths are in agreement with recent published ARPES data [F.
Mazzola et al., Phys.~Rev.~B. 95, 075430 (2017)] and of the band
linewidth with ARPES data presented here.Comment: 7 pages, 4 figure
Concepts and procedures used to determine certain sea wave characteristics
A technique and its application are presented by which wave parameters, critical to spacecraft water impact load analysis, may be determined
- …