Track Dynamics Research Contents and Related Standards

2021 ◽  
pp. 1-39
Author(s):  
Xiaoyan Lei
Keyword(s):  
Track Dynamics

scholarly journals Cyclonic and anticyclonic contributions to atmospheric energetics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Satoru Okajima ◽  
Hisashi Nakamura ◽  
Yohai Kaspi
Keyword(s):  
Storm Track ◽  
Mean Flow ◽  
Weather Variability ◽  
Jet Streams ◽  
Near Surface ◽  
Westerly Jet ◽  
Track Dynamics ◽  
New Findings ◽  
Atmospheric Energetics ◽  
Thermally Driven

AbstractMigratory cyclones and anticyclones account for most of the day-to-day weather variability in the extratropics. These transient eddies act to maintain the midlatitude jet streams by systematically transporting westerly momentum and heat. Yet, little is known about the separate contributions of cyclones and anticyclones to their interaction with the westerlies. Here, using a novel methodology for identifying cyclonic and anticyclonic vortices based on curvature, we quantify their separate contributions to atmospheric energetics and their feedback on the westerly jet streams as represented in Eulerian statistics. We show that climatological westerly acceleration by cyclonic vortices acts to dominantly reinforce the wintertime eddy-driven near-surface westerlies and associated cyclonic shear. Though less baroclinic and energetic, anticyclones still play an important role in transporting westerly momentum toward midlatitudes from the upper-tropospheric thermally driven jet core and carrying eddy energy downstream. These new findings have uncovered essential characteristics of atmospheric energetics, storm track dynamics and eddy-mean flow interaction.

scholarly journals Observed Storm Track Dynamics in Drake Passage

2019 ◽  
Vol 49 (3) ◽  
pp. 867-884 ◽  
Author(s):  
Annie Foppert
Keyword(s):  
Mean Field ◽  
Storm Track ◽  
Drake Passage ◽  
Polar Front ◽  
Mean Flow ◽  
Track Dynamics ◽  
Flow Interactions ◽  
Circumpolar Current ◽  
Eddy Potential Energy ◽  
Shackleton Fracture Zone

AbstractThe dynamics of an oceanic storm track—where energy and enstrophy transfer between the mean flow and eddies—are investigated using observations from an eddy-rich region of the Antarctic Circumpolar Current downstream of the Shackleton Fracture Zone (SFZ) in Drake Passage. Four years of measurements by an array of current- and pressure-recording inverted echo sounders deployed between November 2007 and November 2011 are used to diagnose eddy–mean flow interactions and provide insight into physical mechanisms for these transfers. Averaged within the upper to mid-water column (400–1000-m depth) and over the 4-yr-record mean field, eddy potential energy is highest in the western part of the storm track and maximum eddy kinetic energy occurs farther away from the SFZ, shifting the proportion of eddy energies from to about 1 along the storm track. There are enhanced mean 3D wave activity fluxes immediately downstream of SFZ with strong horizontal flux vectors emanating northeast from this region. Similar patterns across composites of Polar Front and Subantarctic Front meander intrusions suggest the dynamics are set more so by the presence of the SFZ than by the eddy’s sign. A case study showing the evolution of a single eddy event, from 15 to 23 July 2010, highlights the storm-track dynamics in a series of snapshots. Consistently, explaining the eddy energetics pattern requires both horizontal and vertical components of W, implying the importance of barotropic and baroclinic processes and instabilities in controlling storm-track dynamics in Drake Passage.

scholarly journals Labor Drops: Experimental Evidence on the Return to Additional Labor in Microenterprises

2019 ◽  
Vol 11 (1) ◽  
pp. 202-235 ◽  
Author(s):  
Suresh de Mel ◽  
David McKenzie ◽  
Christopher Woodruff
Keyword(s):  
Sri Lanka ◽  
Field Experiment ◽  
Experimental Evidence ◽  
Short Term ◽  
Wage Subsidies ◽  
Track Dynamics ◽  
Additional Labor

A field experiment in Sri Lanka provided wage subsidies to randomly chosen microenterprises to test whether hiring additional labor benefits such firms and whether a short-term subsidy can have a lasting impact on firm employment. Using 12 rounds of surveys to track dynamics 4 years after treatment, we find that firms increased employment during the subsidy period. Treated firms were more likely to survive, but there was no lasting impact on employment and no effect on profitability or sales either during or after the subsidy period. There is some heterogeneity in effects; the subsidies have a more durable effect on manufacturers. (JEL C93, J22, J24, J31, J38, O14, O15)

IMPORTANCE OF NONLINEARITY OF TRACK SUPPORT SYSTEM IN MODELING OF RAILWAY TRACK DYNAMICS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350008 ◽  
Author(s):  
J. SADEGHI ◽  
M. FESHARAKI
Keyword(s):  
Support System ◽  
Field Tests ◽  
Field Investigation ◽  
Dynamic Responses ◽  
Railway Track ◽  
Nonlinear Properties ◽  
Railway Tracks ◽  
Track Dynamics ◽  
Track System ◽  
Axle Loads

Attention is drawn to the fact that the recent increase in axle loads, speed and traffic volume in railway tracks, as well as concerns over passengers' riding comfort and safety have resulted in fresh challenges that are needed to be addressed. These challenges can only be successfully tackled with a more accurate modeling of the dynamic behavior of railway tracks. Although a significant amount of research involving mathematical modeling of railway track dynamics has been conducted in the last two decades, the nonlinearity of track support systems has not been given sufficient attention. This paper is concerned with the effect of nonlinearity of the support sub-layers on the dynamic responses of the railway track. To this end, a railway track model that considers the nonlinear properties of the track sub-layers is developed. Then, a field investigation into the dynamic responses of the railway track system under moving trains is conducted. The effect of the nonlinearity properties of the track support system on the track responses is investigated by comparing the results obtained by the numerical model, with or without consideration of track support nonlinearity, with those from the field tests. It is illustrated that consideration of the nonlinear properties of the track support system improves the accuracy of the calculated responses by a factor of three. It is also shown that the train axle loads and track accumulative loading have a significant effect on the nonlinearity of the track support system and, as a result, on the modeling of track responses.

Dynamic Analysis of Bridge-Approach Embankment Transition Segment

2012 ◽  
Vol 238 ◽  
pp. 719-722
Author(s):  
Zhen Xia Li ◽  
Yuan Zhao Chen
Keyword(s):  
Dynamic Analysis ◽  
Coupled System ◽  
Dynamic Responses ◽  
Subgrade Reaction ◽  
Track Dynamics ◽  
Bridge Approach

Dynamic responses of coupled system were analyzed when the speed of train was 350km/h and the transition was filled with graded broken stones mixed 5% cement. Results indicate that setting form of bridge-approach embankment section has little effect on dynamic responses, thus designers can choose it on account of practical circumstances. Based on the study from vehicle-track dynamics, we suggest that the coefficient of subgrade reaction (K30) should be greater than 190MPa within 0-5m zone behind abutment and be greater than 150MPa in other zones.

Sign in / Sign up

Export Citation Format

Share Document