12,162 research outputs found
Flow losses in flexible hose, volume 1 Final report
Empirical method for predicting flow loss of gas or liquid in flexible hose
A note on leapfrogging vortex rings
In this paper we provide examples, by numerical simulation using the Navier-Stokes equations for axisymmetric laminar flow, of the 'leapfrogging' motion of two, initially identical, vortex rings which share a common axis of symmetry. We show that the number of clear passes that each ring makes through the other increases with Reynolds number, and that as long as the configuration remains stable the two rings ultimately merge to form a single vortex ring
Flexible New Deal evaluation: customer survey and qualitative research findings
by Sandra Vegeris, Lorna Adams, Katie Oldfield, Christine Bertram, Rosemary Davidson, Lucia Durante, Catherine Riley and Kim Vowden
This report presents qualitative and quantitative research findings from an evaluation of the Flexible New Deal (FND), Phase 1 of which was introduced in October 2009 in 28 Jobcentre Plus districts in England, Scotland and Wales.
The research consisted of qualitative research into customer and provider experiences of FND delivery and a quantitative survey of customer experiences of FND in Phase 1 areas compared with customers at the same point in their claims experiencing the former Jobseeker’s Allowance (JSA) regime and New Deals in Phase 2 areas. Comparisons between the two areas provide an indication of FND services in contrast to JSA/New Deal services but they do not constitute an impact assessment.
This is the fourth in a series of evaluation reports aiming to understand experiences of the Jobseekers Regime and Flexible New Deal (JRFND) from the point of view of customers, Jobcentre Plus staff and provider staff, and establish the extent to which JRFND leads to additional customer employment outcomes
Jobseekers Regime and Flexible New Deal, the Six Month Offer and Support for the Newly Unemployed evaluations: An early process study
Not availabl
A Computer Model of the Quantity and Chemical Quality of Return Flow
A hybrid computer program is developed to predict the water and salt outflow from a river basin in which irrigation is the major water user. A chemical model which predicts the quality of water percolated through a soil profile is combined with a general hydrologic model into form the system simulation model. The chemical model considers the reactions that occur in the soil, including the exchange of calcium, magnesium, and sodium cations on the soil complex, and the dissolution and precipitation of gypsum and lime. The chemical composition of the outflow is a function of these chemical processes within the soil, plus bending of undiverted inflows, evaporations, transpirations, and the mixing of subsurface return flows with groundwater. The six common ions of western waters, namely calcium (Ca++), magnesium Mg ++), sodium (Na +), sulfate (SO 4=), chloride (Cl-), and bicarbonate (HCO3-), are considered in the study. Total dissolved solids (TDS) outflow is obtained by adding the individual ions. The overall model operates on monthly time increments. The model is tested on a portion of the Little Bear River Basin in northern Utah. The model successfully simulates measured outflows of water and each of the six ions for a 24-month period. Only sodium ions, which occurred in small concentrations comprising approximately 2 percent of the total salt outflow, exhibit significant discrepancies between predicted and observed values. All other ions agree within 10 percent on a weight basis for the two-year model period, with correlation coefficients ranging from .87 to .97. The usefulness of the model is demonstrated by a management study of the prototype system. For example, preliminary results indicated that the available water supply could be used to irrigate additional land without unduly increasing the salt outflow from the basin. With minor adjustments the model can be applied to other areas
Neutrino-induced deuteron disintegration experiment
Cross sections for the disintegration of the deuteron via neutral-current
(NCD) and charged-current (CCD) interactions with reactor antineutrinos are
measured to be 6.08 +/- 0.77 x 10^(-45) cm-sq and 9.83 +/- 2.04 x 10^(-45)
cm-sq per neutrino, respectively, in excellent agreement with current
calculations. Since the experimental NCD value depends upon the CCD value, if
we use the theoretical value for the CCD reaction, we obtain the improved value
of 5.98 +/- 0.54 x 10^(-45) for the NCD cross section. The neutral-current
reaction allows a unique measurement of the isovector-axial vector coupling
constant in the hadronic weak interaction (beta). In the standard model, this
constant is predicted to be exactly 1, independent of the Weinberg angle. We
measure a value of beta^2 = 1.01 +/- 0.16. Using the above improved value for
the NCD cross section, beta^2 becomes 0.99 +/- 0.10.Comment: 22pages, 9 figure
Study of the April 20, 2007 CME-Comet Interaction Event with an MHD Model
This study examines the tail disconnection event on April 20, 2007 on comet
2P/Encke, caused by a coronal mass ejection (CME) at a heliocentric distance of
0.34 AU. During their interaction, both the CME and the comet are visible with
high temporal and spatial resolution by the STEREO-A spacecraft. Previously,
only current sheets or shocks have been accepted as possible reasons for comet
tail disconnections, so it is puzzling that the CME caused this event. The MHD
simulation presented in this work reproduces the interaction process and
demonstrates how the CME triggered a tail disconnection in the April 20 event.
It is found that the CME disturbs the comet with a combination of a
sudden rotation of the interplanetary magnetic field (IMF), followed by a
gradual rotation. Such an interpretation applies our understanding
of solar wind-comet interactions to determine the \textit{in situ} IMF
orientation of the CME encountering Encke.Comment: 13 pages, 3 figures, accepted by the ApJ Letter
Inclined Surface Locomotion Strategies for Spherical Tensegrity Robots
This paper presents a new teleoperated spherical tensegrity robot capable of
performing locomotion on steep inclined surfaces. With a novel control scheme
centered around the simultaneous actuation of multiple cables, the robot
demonstrates robust climbing on inclined surfaces in hardware experiments and
speeds significantly faster than previous spherical tensegrity models. This
robot is an improvement over other iterations in the TT-series and the first
tensegrity to achieve reliable locomotion on inclined surfaces of up to
24\degree. We analyze locomotion in simulation and hardware under single and
multi-cable actuation, and introduce two novel multi-cable actuation policies,
suited for steep incline climbing and speed, respectively. We propose
compelling justifications for the increased dynamic ability of the robot and
motivate development of optimization algorithms able to take advantage of the
robot's increased control authority.Comment: 6 pages, 11 figures, IROS 201
Recommended from our members
A Qualitative Assessment of a Modified Multilevel Converter Topology M2LeC for Lightweight Low-cost Electric Propulsion
A Cascade H Bridge (CHB) is evaluated for both electric vehicle motor traction control and off-vehicle charging against the PowerElectronicsUK Automotive Challenge for cost and mass for the year 2035. By combining the power electronics with batteries using low-voltage MOSFET transistors in a series cascade arrangement the cost and mass targets could be met 12 years earlier (in 2023 and 20 times lighter if an application specific integrated circuit (ASIC) is used.
A 200kW peak reference car was used to evaluate cost and mass benefits using four different topologies of power electronics.
Vehicle installation is shown to be simplified as only passive cooling is required removing the need for liquid cooling systems and the arrangement is inherently safe; no high voltages are present when the vehicle is stationary. The inherently higher efficiency of CHB increases vehicle range.
The converter with integrated batteries can also behave as an integrated on-board battery charger delivering additional off-vehicle benefits by removing the need for costly external chargers
- …