17,319 research outputs found
Influence of wear algorithm formulation on computational-experimental corroboration
Experimental wear testing is well-established as an important part of the TKR design process. Recently, in-silico models have proved their value to corroborate long-term in-vitro results on a much shorter timescale [1]. Both FE-based models & multi-body dynamics can be used to predict contact pressures, sliding distances and cross-shear (CS). The precise mechanisms of wear are not sufficiently understood to permit analytical calculations, and so empirical formulations are used to estimate wear depths & volumes.Most early simulations were based on a modified Archard/Lancaster formulation; more recently a number of alternative formulations for cross shear have been proposed; it is unclear which is the most robust or accurate for the widest range of activities. The aim of this study was to develop and corroborate a fast in-silico wear model, and use this to compare different wear formulations
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CamGrid: Experiences in constructing a university-wide, Condor-based grid at the University of Cambridge
Proceedings of the 2004 UK e-Science All Hands Meeting, 31st August - 3rd September, Nottingham UKIn this article we describe recent work done in building a university-wide grid at the University of Cambridge based on the Condor middleware [1]. Once the issues of stakeholder concerns (e.g.
security policies) and technical problems (e.g. firewalls and private IP addresses) have been taken into account, a solution based on two separate Condor environments was decided on. The first of these is a single large pool administered centrally by the University Computing Service (UCS) and
the second a federated service of flocked Condor pools belonging to various departments and run over a Virtual Private Network (VPN). We report on the current status of this ongoing work
The Helper-Therapy Principle Applied to Weight Management Specialists
One hundred twenty applicants to a weight management specialist training program were studied over a 33-month period. Following a nine-month training period, Specialists (N = 29; those leading at least one posttraining weight management group) were compared to Contact Controls (N = 31; persons participating in the weight management program, but not in the helper role) and No Contact Controls (N = 60; those not accepted into the training program and whose only contact with the program was for data collection purposes) in a test of the helper-therapy principle. The major question was, What are the long-term physical, psychological, and behavioral effects on overweight and formerly overweight individuals involved in helping other persons manage their weight? Data gathered at 12 and 24 months posttraining revealed few differences between the total group of specialists and persons in the two control groups. However, when the data were analyzed by the amount of commitment to the specialist role, it was found that the Higher Involved Specialists (N = 16; those who led two or more weight management groups in the year posttraining) were significantly more likely to lose additional weight (or maintain earlier weight losses), to be more consistent in their adherence to the eating and activity levels advocated by the program, to feel better about themselves and their bodies, and to maintain their levels of general well-being than control subjects or the Lesser Involved Specialists. These latter individuals (N = 13) were significantly the worse for having gone through specialist training, but not fully carrying out the specialist role
Childrenâs Perceptions of Cohesion
The general purpose of the two studies reported here was to examine perceptions of team cohesiveness in children aged 9 to 12 years. In Study 1, focus groups were used to examine individual perceptions of cohesion from the perspective of group integrationâthe group as a totality. In Study 2, open-ended questionnaires were used to examine individual perceptions of cohesion from the perspective of individual attractions to the group. The results showed that children as young as nine years understand the phenomenon known as cohesion. They can discuss the group as a totality, the characteristics of cohesive and non-cohesive teams, and identify the major factors attracting them to and maintaining their involvement in the group. Also, the ability to clearly distinguish between task and social cohesion is present. The results provide insight into the world of child sport and emphasise the importance of group cohesion, affiliation, and other social constructs in childrenâs involvement and adherence to sport groups
Optical and RF Metrology for 5G
Specification standards will soon be available for 5G mobile RF
communications. What optical and electrical metrology is needed or available to
support the development of the supporting optical communication systems? Device
measurement, digital oscilloscope impairments and improving system resolution
are discussed.Comment: 2017 IEEE Photonics Society Summer Topical Meeting Series (SUM
CMB power spectra from cosmic strings: predictions for the Planck satellite and beyond
We present a significant improvement over our previous calculations of the
cosmic string contribution to cosmic microwave background (CMB) power spectra,
with particular focus on sub-WMAP angular scales. These smaller scales are
relevant for the now-operational Planck satellite and additional sub-orbital
CMB projects that have even finer resolutions. We employ larger Abelian Higgs
string simulations than before and we additionally model and extrapolate the
statistical measures from our simulations to smaller length scales. We then use
an efficient means of including the extrapolations into our Einstein-Boltzmann
calculations in order to yield accurate results over the multipole range 2 < l
3000 in
the case of the temperature power spectrum, which then allows cautious
extrapolation to even smaller scales. We find that a string contribution to the
temperature power spectrum making up 10% of power at l=10 would be larger than
the Silk-damped primary adiabatic contribution for l > 3500. Astrophysical
contributions such as the Sunyaev-Zeldovich effect also become important at
these scales and will reduce the sensitivity to strings, but these are
potentially distinguishable by their frequency-dependence.Comment: 18 pages, 16 figure
CMB power spectrum contribution from cosmic strings using field-evolution simulations of the Abelian Higgs model
We present the first field-theoretic calculations of the contribution made by
cosmic strings to the temperature power spectrum of the cosmic microwave
background (CMB). Unlike previous work, in which strings were modeled as
idealized one-dimensional objects, we evolve the simplest example of an
underlying field theory containing local U(1) strings, the Abelian Higgs model.
Limitations imposed by finite computational volumes are overcome using the
scaling property of string networks and a further extrapolation related to the
lessening of the string width in comoving coordinates. The strings and their
decay products, which are automatically included in the field theory approach,
source metric perturbations via their energy-momentum tensor, the unequal-time
correlation functions of which are used as input into the CMB calculation
phase. These calculations involve the use of a modified version of CMBEASY,
with results provided over the full range of relevant scales. We find that the
string tension required to normalize to the WMAP 3-year data at multipole
is , where we have quoted statistical and systematic errors
separately, and is Newton's constant. This is a factor 2-3 higher than
values in current circulation.Comment: 23 pages, 14 figures; further optimized figures for 1Mb size limit,
appendix added before submission to journal, matches accepted versio
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