91,297 research outputs found
Wear and Friction Modeling on Lifeboat Launch Systems
The RNLI provides search and rescue cover along the UK and RoI coast using a variety of lifeboats
and launch techniques. In locations where there is no natural harbour it is necessary to use a slipway
to launch the lifeboat into the sea. Lifeboat slipway stations consist of an initial section where the
boat is held on rollers followed by an inclined keelway lined with low friction composite materials,
the lifeboat is released from the top of the slipway and proceeds under its own weight into the water.
The lifeboat is later recovered using a winch line. It is common to manually apply grease to the
composite slipway lining before each launch and recovery in order to ensure sufficiently low friction
for successful operation. With the introduction of the Tamar class lifeboat it is necessary to upgrade
existing boathouses and standardise slipway operational procedures to ensure consistent operation.
The higher contact pressures associated with the new lifeboat have led to issues of high friction and
wear on the composite slipway linings and the manual application of grease to reduce friction is to be
restricted due to environmental impact and cost factors. This paper presents a multidisciplinary
approach to modelling slipway panel wear and friction using tribometer testing in conjunction with
finite element analysis and slipway condition surveys to incorporate common real-world effects such
as panel misalignments. Finally, it is shown that a freshwater lubrication system is effective,
reducing cost and environmental impacts while maintaining good friction and wear performance
Enhancing Care Transitions for Older People through Interprofessional Simulation: A Mixed Method Evaluation
Introduction: The educational needs of the health and social care workforce for delivering effective integrated care are important. This paper reports on the development, pilot and evaluation of an interprofessional simulation course, which aimed to support integrated care models for care transitions for older people from hospital to home.
Theory and methods:
The course development was informed by a literature review and a scoping exercise with the health and social care workforce. The course ran six times and was attended by health and social care professionals from hospital and community (n=49). The evaluation aimed to elicit staff perceptions of their learning about care transfers of older people and to explore application of learning into practice and perceived outcomes. The study used a sequential mixed method design with questionnaires completed pre (n=44) and post (n=47) course and interviews (n=9) 2-5 months later.
Results:Participants evaluated interprofessional simulation as a successful strategy. Post-course, participants identified learning points and at the interviews, similar themes with examples of application in practice were: Understanding individual needs and empathy; Communicating with patients and families; Interprofessional working; Working across settings to achieve effective care transitions.
Conclusions and discussion:An interprofessional simulation course successfully brought together health and social care professionals across settings to develop integrated care skills and improve care transitions for older people with complex needs from hospital to home
Time frequency requirements for radio interferometric earth physics
Two systems of VLBI (Very Long Baseline Interferometry) are now applicable to earth physics: an intercontinental baseline system using antennas of the NASA Deep Space Network, now observing at one-month intervals to determine UTI for spacecraft navigation; and a shorter baseline system called ARIES (Astronomical Radio Interferometric Earth Surveying), to be used to measure crustal movement in California for earthquake hazards estimation. On the basis of experience with the existing DSN system, a careful study has been made to estimate the time and frequency requirements of both the improved intercontinental system and of ARIES. Requirements for the two systems are compared and contrasted
Dark Matter Annihilation Signatures from Electroweak Bremsstrahlung
We examine observational signatures of dark matter annihilation in the Milky
Way arising from electroweak bremsstrahlung contributions to the annihilation
cross section. It has been known for some time that photon bremsstrahlung may
significantly boost DM annihilation yields. Recently, we have shown that
electroweak bremsstrahlung of W and Z gauge bosons can be the dominant
annihilation channel in some popular models with helicity-suppressed 2 --> 2
annihilation. W/Z-bremsstrahlung is particularly interesting because the gauge
bosons produced via annihilation subsequently decay to produce large correlated
fluxes of electrons, positrons, neutrinos, hadrons (including antiprotons) and
gamma rays, which are all of importance in indirect dark matter searches. Here
we calculate the spectra of stable annihilation products produced via
gamma/W/Z-bremsstrahlung. After modifying the fluxes to account for the
propagation through the Galaxy, we set upper bounds on the annihilation cross
section via a comparison with observational data. We show that stringent cosmic
ray antiproton limits preclude a sizable dark matter contribution to observed
cosmic ray positron fluxes in the class of models for which the bremsstrahlung
processes dominate.Comment: 11 pages, 6 figures. Updated to match PRD versio
On the Hierarchical Preconditioning of the Combined Field Integral Equation
This paper analyzes how hierarchical bases preconditioners constructed for
the Electric Field Integral Equation (EFIE) can be effectively applied to the
Combined Field Integral Equation (CFIE). For the case where no hierarchical
solenoidal basis is available (e.g., on unstructured meshes), a new scheme is
proposed: the CFIE is implicitly preconditioned on the solenoidal Helmholtz
subspace by using a Helmholtz projector, while a hierarchical non-solenoidal
basis is used for the non-solenoidal Helmholtz subspace. This results in a
well-conditioned system. Numerical results corroborate the presented theory
Electroweak Bremsstrahlung in Dark Matter Annihilation
A conservative upper bound on the total dark matter (DM) annihilation rate
can be obtained by constraining the appearance rate of the annihilation
products which are hardest to detect. The production of neutrinos, via the
process , has thus been used to set a strong
general bound on the dark matter annihilation rate. However, Standard Model
radiative corrections to this process will inevitably produce photons which may
be easier to detect. We present an explicit calculation of the branching ratios
for the electroweak bremsstrahlung processes and
. These modes inevitably lead to electromagnetic
showers and further constraints on the DM annihilation cross-section. In
addition to annihilation, our calculations are also applicable to the case of
dark matter decay.Comment: 7 pages, 4 figures. New appendix with an extensive discussion of
Majorana fermions and helicity suppression
Critical behavior of the three-dimensional bond-diluted Ising spin glass: Finite-size scaling functions and Universality
We study the three-dimensional (3D) bond-diluted Edwards-Anderson (EA) model
with binary interactions at a bond occupation of 45% by Monte Carlo (MC)
simulations. Using an efficient cluster MC algorithm we are able to determine
the universal finite-size scaling (FSS) functions and the critical exponents
with high statistical accuracy. We observe small corrections to scaling for the
measured observables. The critical quantities and the FSS functions indicate
clearly that the bond-diluted model for dilutions above the critical dilution
p*, at which a spin glass (SG) phase appears, lies in the same universality
class as the 3D undiluted EA model with binary interactions. A comparison with
the FSS functions of the 3D site-diluted EA model with Gaussian interactions at
a site occupation of 62.5% gives very strong evidence for the universality of
the SG transition in the 3D EA model.Comment: Revised version. 10 pages, 9 figures, 2 table
Assumptions that imply quantum dynamics is linear
A basic linearity of quantum dynamics, that density matrices are mapped
linearly to density matrices, is proved very simply for a system that does not
interact with anything else. It is assumed that at each time the physical
quantities and states are described by the usual linear structures of quantum
mechanics. Beyond that, the proof assumes only that the dynamics does not
depend on anything outside the system but must allow the system to be described
as part of a larger system. The basic linearity is linked with previously
established results to complete a simple derivation of the linear Schrodinger
equation. For this it is assumed that density matrices are mapped one-to-one
onto density matrices. An alternative is to assume that pure states are mapped
one-to-one onto pure states and that entropy does not decrease.Comment: 10 pages. Added references. Improved discussion of equations of
motion for mean values. Expanded Introductio
Solution of nonlinear algebraic equations characteristic of filter circuits Summary technical report
Digital computer program developed for solving nonlinear algebraic equations characteristic of filter circuit
Recent changes to the Federal Reserve's survey of terms of business lending
The Federal Reserve's quarterly Survey of Terms of Business Lending, which has been conducted for more than twenty years, collects information on interest rates and other characteristics of commercial bank business loans. The survey has been changed from time to time to recognize innovations in bank lending practices and to improve the measurement of the desired information. The most recent changes took effect with the May 1997 survey. The major improvement was the addition of an item measuring loan risk. In addition, the reporting panel, which had been limited to domestically chartered commercial banks was expanded to include a sample of U.S. branches and agencies of foreign banks, which now account for a significant proportion of business lending to U.S. firms. This article discusses the most recent changes made to the survey and presents some information now available from the new items being reported. It also summarizes information about the use of loan risk ratings from consultations conducted with a sample of the survey respondents during the process of planning the revisions to the survey.Commercial loans
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