14,786 research outputs found
A general purpose programming framework for ubiquitous computing environments
It is important to note that the need to support ad-hoc and potentially mobile arrangements of devices in ubiquitous environments does not fit well within the traditional client/server architecture. We believe peer-to-peer communication offers a preferable alternative due to its decentralised nature, removing dependence on individual nodes. However, this choice adds to the complexity of the developers task. In this paper, we describe a two-tiered approach to address this problem: A lower tier employing peer-to-peer interactions for managing the network infrastructure and an upper tier providing a mobile agent based programming framework. The result is a general purpose framework for developing ubiquitous applications and services, where the underlying complexity is hidden from the developer. This paper discusses our on-going work; presenting our design decisions, features supported by our framework, and some of the challenges still to be addressed in a complex programming environment
A self-managing infrastructure for ad-hoc situation determination
Automatically determining the situation of an ad-hoc group of people and devices within a smart environment is a significant challenge in pervasive computing systems. Current approaches often rely on an environment expert to correlate the situations that occur with the available sensor data, while other machine learning based approaches require long training periods before the system can be used. This paper presents a novel approach to situation determination that attempts to overcome these issues by providing a reusable library of general situation specifications that can be easily extended to create new specific situations, and immediately deployed without the need of an environment expert. The architecture of an accompanying situation determination infrastructure is provided, which autonomously optimises and repairs itself in reaction to changes or failures in the environment
Development of anlytical techniques for hydrocarbons in mineral aggregates quarterly status report no. 4, jul. - sep. 1964
Chemical analysis of rock and meteorite samples for hydrocarbon conten
Crucial Dependence of ``Precarious'' and ``Autonomous'' phi^4s Upon the Normal-ordering Mass
Using the Gaussian wave-functional approach with the normal-ordering
renormalization prescription, we show that for the (3+1)-dimensional massive
lambda phi^4 theory, ``precarious'' and ``autonomous'' phi^4s can exist if and
only if the normal-ordering mass is equal to the classical masses at the
symmetrc and asymmetric vacua, respectively.Comment: 6 pages, no figures, Revtex file, accepted for publication in Mod.
Phys. Lett.
How do sound waves in a Bose-Einstein condensate move so fast?
Low-momentum excitations of a dilute Bose-Einstein condensate behave as
phonons and move at a finite velocity v_s. Yet the atoms making up the phonon
excitation each move very slowly; v_a = p/m --> 0. A simple "cartoon picture"
is suggested to understand this phenomenon intuitively. It implies a relation
v_s/v_a = N_ex, where N_ex is the number of excited atoms making up the phonon.
This relation does indeed follow from the standard Bogoliubov theory.Comment: 6 pages, 2 figures (.eps), LaTeX2e. More introductory discussion
adde
A New Medicare End-of-Life Benefit for Nursing Home Residents
A new Medicare benefit is needed to support end-of-life care for those spending their final days in a nursing home, say the authors of this article. Arguing that the current hospice benefit is a poor fit with the nursing home setting, the authors recommend a new benefit that would enable nursing home residents to receive individualized palliative and psychosocial services in addition to rehabilitative services
The four-fermion interaction in D=2,3,4: a nonperturbative treatment
A new nonperturbative approach is used to investigate the Gross-Neveu model
of four fermion interaction in the space-time dimensions 2, 3 and 4, the number
of inner degrees of freedom being a fixed integer. The spontaneous symmetry
breaking is shown to exist in and the running coupling constant is
calculated. The four dimensional theory seems to be trivial.Comment: a minor correction: one more acknowledgement is added. Latex 2.09
file, 15 pages, no figures, accepted for publication to Int.J.Mod.Phys.
A lattice test of alternative interpretations of ``triviality'' in theory
There are two physically different interpretations of ``triviality'' in
theories. The conventional description predicts a
second-order phase transition and that the Higgs mass must vanish in the
continuum limit if , the physical v.e.v, is held fixed. An alternative
interpretation, based on the effective potential obtained in
``triviality-compatible'' approximations (in which the shifted `Higgs' field
is governed by an effective quadratic Hamiltonian)
predicts a phase transition that is very weakly first-order and that and
are both finite, cutoff-independent quantities. To test these two
alternatives, we have numerically computed the effective potential on the
lattice. Three different methods were used to determine the critical bare mass
for the chosen bare coupling value. All give excellent agreement with the
literature value. Two different methods for obtaining the effective potential
were used, as a control on the results. Our lattice data are fitted very well
by the predictions of the unconventional picture, but poorly by the
conventional picture.Comment: 16 pages, LaTeX, 2 eps figures (acknowledgements added in the
replaced version
Fabrication of free-standing ordered fluorescent polymer nanofibres by electrospinning
The authors are grateful to the Engineering and Physical Sciences Research Council for financial support.We demonstrate a static fabrication approach to make free-standing ordered arrays of fluorescent nanofibres through control of the transverse electrospinning field. The alignment and the density of the nanofibre arrays are optimised by careful design of both the source and collector electrode geometries which can control the transverse electric field over the full path of the jet. In doing so, we fabricate suspended fluorescent nanofibres with an aspect ratio of 10(4), and with a substantially increased density and order parameter (by a factor of similar to 10 compared to random deposition). Electrostatic modelling suggests that the field distribution of the component is the main contribution to the ordering between the plates. This method offers increased efficiency for the creation of ordered fibres collected over a small area and the characterisation of their photoluminescent properties.Publisher PDFPeer reviewe
Relating Physical Observables in QCD without Scale-Scheme Ambiguity
We discuss the St\"uckelberg-Peterman extended renormalization group
equations in perturbative QCD, which express the invariance of physical
observables under renormalization-scale and scheme-parameter transformations.
We introduce a universal coupling function that covers all possible choices of
scale and scheme. Any perturbative series in QCD is shown to be equivalent to a
particular point in this function. This function can be computed from a set of
first-order differential equations involving the extended beta functions. We
propose the use of these evolution equations instead of perturbative series for
numerical evaluation of physical observables. This formalism is free of
scale-scheme ambiguity and allows a reliable error analysis of higher-order
corrections. It also provides a precise definition for as the pole in the associated 't Hooft scheme. A concrete application to
is presented.Comment: Plain TEX, 4 figures (available upon request), 22 pages,
DOE/ER/40322-17
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