10,652 research outputs found
Three-dimensional coating and rimming flow: a ring of fluid on a rotating horizontal cylinder
The steady three-dimensional flow of a thin, slowly varying ring of Newtonian fluid on either the outside or the inside of a uniformly rotating large horizontal cylinder is investigated. Specifically, we study “full-ring” solutions, corresponding to a ring of continuous, finite and non-zero thickness that extends all the way around the cylinder. In particular, it is found that there is a critical solution corresponding to either a critical load above which no full-ring solution exists (if the rotation speed is prescribed) or a critical rotation speed below which no full-ring solution exists (if the load is prescribed). We describe the behaviour of the critical solution and, in particular, show that the critical flux, the critical load, the critical semi-width and the critical ring profile are all increasing functions of the rotation speed. In the limit of small rotation speed, the critical flux is small and the critical ring is narrow and thin, leading to a small critical load. In the limit of large rotation speed, the critical flux is large and the critical ring is wide on the upper half of the cylinder and thick on the lower half of the cylinder, leading to a large critical load.\ud
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We also describe the behaviour of the non-critical full-ring solution, and, in particular, show that the semi-width and the ring profile are increasing functions of the load but, in general, non-monotonic functions of the rotation speed. In the limit of large rotation speed, the ring approaches a limiting non-uniform shape, whereas in the limit of small load, the ring is narrow and thin with a uniform parabolic profile. Finally, we show that, while for most values of the rotation speed and the load the azimuthal velocity is in the same direction as the rotation of the cylinder, there is a region of parameter space close to the critical solution for sufficiently small rotation speed in which backflow occurs in a small region on the right-hand side of the cylinder
Thermoviscous Coating and Rimming Flow
A comprehensive description is obtained of steady thermoviscous (i.e. with temperature-dependent viscosity) coating and rimming flow on a uniformly rotating horizontal cylinder that is uniformly hotter or colder than the surrounding atmosphere. It is found that, as in the corresponding isothermal problem, there is a critical solution with a corresponding critical load (which depends, in general, on both the Biot number and the thermoviscosity number) above which no ``full-film'' solutions corresponding to a continuous film of fluid covering the entire outside or inside of the cylinder exist. The effect of thermoviscosity on both the critical solution and the full-film solution with a prescribed load is described. In particular, there are no full-film solutions with a prescribed load M for any value of the Biot number when M is greater than or equal to M_{c0} divided by the square root of f for positive thermoviscosity number and when M is greater than M_{c0} for negative thermoviscosity number, where f is a monotonically decreasing function of the thermoviscosity number and M_{c0} = 4.44272 is the critical load in the constant-viscosity case. It is also found that when the prescribed load M is less than 1.50315 there is a narrow region of the Biot number - thermoviscosity number parameter plane in which backflow occurs
Growth or decline in the Church of England during the decade of Evangelism: did the Churchmanship of the Bishop matter?
The Decade of Evangelism occupied the attention of the Church of England throughout the 1990s. The present study employs the statistics routinely published by the Church of England in order to assess two matters: the extent to which these statistics suggest that the 43 individual dioceses finished the decade in a stronger or weaker position than they had entered it and the extent to which, according to these statistics, the performance of dioceses led by bishops shaped in the Evangelical tradition differed from the performance of dioceses led by bishops shaped in the Catholic tradition. The data demonstrated that the majority of dioceses were performing less effectively at the end of the decade than at the beginning, in terms of a range of membership statistics, and that the rate of decline varied considerably from one diocese to another. The only exception to the trend was provided by the diocese of London, which experienced some growth. The data also demonstrated that little depended on the churchmanship of the diocesan bishop in shaping diocesan outcomes on the performance indicators employed in the study
Studies of discharge mechanisms in high pressure gases-applications to high efficiency high power lasers
By measuring the absorption and emission cantinua of various states in the cesium/xenon molecule, the collisional rates critical in populating the alkali/rare gas excimer levels have been estimated. Cs atomic states that are weakly optically connected to ground have been shown to form excimer levels that are attractive as potential dissociation lasers. In particular, the (Cs/7 2S/Xe) excited molecule appears promising as a source of high energy laser radiation due to its large dissociation energy, stimulated emission cross section, and small population inversion densities. Monitoring of the optically pumped Cs2 molecular absorption profile in the presence of xenon shows a drastic change with increasing xenon pressure for the Cs2C band. Dominant absorption at large xenon densities is centered around approximately 6380 A as opposed to 6300 A for lower perturber pressure
GCS programmer's manual
A variety of instructions to be used in the development of implementations of software for the Guidance and Control Software (GCS) project is described. This document fulfills the Radio Technical Commission for Aeronautics RTCA/DO-178A guidelines, 'Software Considerations in Airborne Systems and Equipment Certification' requirements for document No. 4, which specifies the information necessary for understanding and programming the host computer, and document No. 12, which specifies the software design and implementation standards that are applicable to the software development and testing process. Information on the following subjects is contained: activity recording, communication protocol, coding standards, change management, error handling, design standards, problem reporting, module testing logs, documentation formats, accuracy requirements, and programmer responsibilities
Missed Opportunities in HPV Vaccination
Objective: To use the 3 dose Human Papillomavirus (HPV) vaccine administration (given at 0, 1-2 and 6 months) to quantify opportunities to improve efficacy in the delivery of preventive health services.
Methods: This was a retrospective, claims-based analysis using data provided by a single managed care plan. Female patients aged 9-26 who were continuously enrolled between 2009 through 2011 and received ≥ dose of the HPV vaccine during 2010 were analyzed. The proportion of initiators who did and did not completed the vaccine series, the timing and location of doses, and the number of outpatient visits during which the vaccine could have been given to non-completers were determined.
Results: 1,830 patients were analyzed in the 2010 sample. 843 (46%) were continuously enrolled during the three-year observation period. 500 (59%) completed 3 doses. Among completers, the interval range between doses 1 and 2 was 27-619 days (median 96 days). The interval range between doses 2 and 3 was 32-621 days (median 127 days). 261 (52%) completers received dose 2, and 139 (28%) received does 3 over 1 month late. Among the 343 non-completers, 137 (40%), and 206 (60%) completed 1 and 2 doses, respectively. 63% of single-dose recipients and 17% of 2-dose recipients had at least 1 visit within the eligible time period for administration.
Conclusion: Nearly half of HPV vaccine initiators do not complete the vaccine series. Of those who do, a large percentage complete it late. This example quantifies the potential for reminders, registries and outreach to improve on-time dosage and completion
BOSH:Bayesian Optimization by Sampling Hierarchically
Deployments of Bayesian Optimization (BO) for functions with stochastic evaluations, such as parameter tuning via cross validation and simulation optimization, typically optimize an average of a fixed set of noisy realizations of the objective function. However, disregarding the true objective function in this manner finds a high-precision optimum of the wrong function. To solve this problem, we propose Bayesian Optimization by Sampling Hierarchically (BOSH), a novel BO routine pairing a hierarchical Gaussian process with an information-theoretic framework to generate a growing pool of realizations as the optimization progresses. We demonstrate that BOSH provides more efficient and higher-precision optimization than standard BO across synthetic benchmarks, simulation optimization, reinforcement learning and hyper-parameter tuning tasks
Dense Molecular Gas In A Young Cluster Around MWC 1080 -- Rule Of The Massive Star
We present CS , CO , and CO , observations with the 10-element Berkeley Illinois Maryland Association
(BIMA) Array toward the young cluster around the Be star MWC 1080. These
observations reveal a biconical outflow cavity with size 0.3 and 0.05 pc
for the semimajor and semiminor axis and 45\arcdeg position angle.
These transitions trace the dense gas, which is likely the swept-up gas of the
outflow cavity, rather than the remaining natal gas or the outflow gas. The gas
is clumpy; thirty-two clumps are identified. The identified clumps are
approximately gravitationally bound and consistent with a standard isothermal
sphere density, which suggests that they are likely collapsing protostellar
cores. The gas kinematics suggests that there exists velocity gradients
implying effects from the inclination of the cavity and MWC 1080. The
kinematics of dense gas has also been affected by either outflows or stellar
winds from MWC 1080, and lower-mass clumps are possibly under stronger effects
from MWC 1080 than higher-mass clumps. In addition, low-mass cluster members
tend to be formed in the denser and more turbulent cores, compared to isolated
low-mass star-forming cores. This results from contributions of nearby forming
massive stars, such as outflows or stellar winds. Therefore, we conclude that
in clusters like the MWC 1080 system, effects from massive stars dominate the
star-forming environment in both the kinematics and dynamics of the natal cloud
and the formation of low-mass cluster members. This study provides insights
into the effects of MWC 1080 on its natal cloud, and suggests a different
low-mass star forming environment in clusters compared to isolated star
formation.Comment: 42 pages, 5 tables, and 13 figures, accepted for publication in Ap
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