scholarly journals Lagrangian structures in time-periodic vortical flows

2006 ◽  
Vol 13 (6) ◽  
pp. 621-628 ◽  
Author(s):  
S. V. Kostrykin ◽  
A. A. Khapaev ◽  
V. M. Ponomarev ◽  
I. G. Yakushkin
Keyword(s):  
Velocity Field ◽  
Temporal Change ◽  
Regular Structures ◽  
Flow Parameters ◽  
Qualitative Interpretation ◽  
Time Period ◽  
Long Time ◽  
Adiabatic Chaos ◽  
Short Time ◽  
Time Periodic

Abstract. The Lagrangian trajectories of fluid particles are experimentally studied in an oscillating four-vortex velocity field. The oscillations occur due to a loss of stability of a steady flow and result in a regular reclosure of streamlines between the vortices of the same sign. The Eulerian velocity field is visualized by tracer displacements over a short time period. The obtained data on tracer motions during a number of oscillation periods show that the Lagrangian trajectories form quasi-regular structures. The destruction of these structures is determined by two characteristic time scales: the tracers are redistributed sufficiently fast between the vortices of the same sign and much more slowly transported into the vortices of opposite sign. The observed behavior of the Lagrangian trajectories is quantitatively reproduced in a new numerical experiment with two-dimensional model of the velocity field with a small number of spatial harmonics. A qualitative interpretation of phenomena observed on the basis of the theory of adiabatic chaos in the Hamiltonian systems is given. The Lagrangian trajectories are numerically simulated under varying flow parameters. It is shown that the spatial-temporal characteristics of the Lagrangian structures depend on the properties of temporal change in the streamlines topology and on the adiabatic parameter corresponding to the flow. The condition for the occurrence of traps (the regions where the Lagrangian particles reside for a long time) is obtained.

Non-Labeled Cell Tracking Velocimetry for Biological Flows

2007 ◽  
Author(s):  
Chang-Beom Kim ◽  
Edward Steager ◽  
Min Jun Kim
Keyword(s):  
Velocity Field ◽  
Cell Tracking ◽  
Collective Motion ◽  
Agar Plate ◽  
Soft Agar ◽  
Spatially Correlated ◽  
Time Period ◽  
Entire Flow ◽  
Cell Tracking Velocimetry ◽  
Short Time

A tracking algorithm was developed to study the velocity field of flagellated bacteria, Serratia marcescens, swarming on a soft agar plate. Average velocities for local regions regularly arranged over the entire flow field were investigated rather than those for individual bacterium. The velocity field of the bacteria typically featured the combination of curvilinear translation and vortex modes. They repeated these patterns for a short time period, forming several groups and dissipating. To further investigate the flow patterns generated by the collective motion of the swarming bacteria, the velocity field on the swarm was spatially correlated.

scholarly journals MEMBANGUN MODEL PENYEBARAN PENYAKIT AKIBAT ASAP KEBAKARAN HUTAN

2018 ◽  
Vol 15 (1) ◽  
pp. 36-47
Author(s):  
B Kurniawan ◽  
R Ratianingsih ◽  
Hajar Hajar
Keyword(s):  
Critical Points ◽  
Forest Fires ◽  
Disease Spread ◽  
Asymptotically Stable ◽  
Short Time Period ◽  
Time Period ◽  
Long Time ◽  
The Stability ◽  
Short Time ◽  
Threshold Point

Forest fires impact a very serious problem because it could cause health problem, especially respiratory disease such as (ISPA), Asthma and Bronchitis. The study of the health disorders is conducted by consider mathematicaly the spread of disease due to forest fires smoke. The model is constructed by devide the human population into six subpopulations, that is vulnerable S(t), exposed E(t), Asthma infected A(t), Bronchitis infected B(t) and recovered R(t).The governed model is analyted at every critical points using Routh-Hurwitz method. The results gives two critical points that describe a free disease conditions ( ) and an endemic conditions ( ). A stabil ( ) is occured if  and  where the threshold point of the stability is expressed as  and   . Endemic conditions  will be asymptotically stable when  and  with  . The condition of free disease of forest fires is occured in a long time period, while the endemic conditions is occurred in a short time period. It could be interpreted that the disease spread due to the forest fires smoke is not easy to overcome.

scholarly journals DISTRIBUTIONS OF MONEY IN MODEL MARKETS OF ECONOMY

2002 ◽  
Vol 13 (10) ◽  
pp. 1315-1321 ◽  
Author(s):  
ANIRBAN CHAKRABORTI
Keyword(s):  
Statistical Mechanics ◽  
Economic System ◽  
Power Law ◽  
Short Time Period ◽  
Exponential Tail ◽  
Time Period ◽  
Different Types ◽  
Long Time ◽  
Entire Amount ◽  
Short Time

We study the distributions of money in a simple closed economic system for different types of monetary transactions. We know that for arbitrary and random sharing with locally conserving money transactions, the money distribution goes to the Gibb's distribution of statistical mechanics. We then consider the effects of savings, etc. and see how the distribution changes. We also propose a new model where the agents invest equal amounts of money in each transaction. We find that for short time-period, the money distribution obeys a power-law with an exponent very close to unity, and has an exponential tail; after a very long time, this distribution collapses and the entire amount of money goes to a tiny fraction of the population.

scholarly journals Occasional Hunts or Mass Kills? Investigating the Origins of Archaeological Pronghorn Bonebeds in Southwest Wyoming

2009 ◽  
Vol 74 (2) ◽  
pp. 323-350 ◽  
Author(s):  
Jack N. Fenner
Keyword(s):  
Isotope Ratio ◽  
Tooth Enamel ◽  
Site Formation ◽  
Single Population ◽  
Ratio Variation ◽  
Time Period ◽  
Show Evidence ◽  
Long Time ◽  
Single Mass ◽  
Short Time

It is often unclear whether an archaeological animal bonebed was formed by a mass kill of individuals from a single prey population or through the accumulation of a number of separate kills which occurred over a long time period or at multiple locations. The isotope ratio variation within animals from an archaeological bonebed can be used to investigate this question by comparing the isotope ratio variation within an archaeological assemblage to the variation within modern populations. If the archaeological variation exceeds that expected within a single population, then an accumulation is indicated. Otherwise, a single mass kill or a series of kills from a single population over a fairly short time period is more likely. This technique is demonstrated using carbon, oxygen, and strontium isotope ratios to characterize the amount of variation within pronghorn tooth enamel from six archaeological sites in southwestern Wyoming. The results indicate that the Austin Wash and Trappers Point sites are the result of an accumulation of pronghorn from multiple populations, while the Firehole Basin, Gailiun, and Boars Tusk sites do not show evidence of accumulation and therefore may be the result of mass kills. The Eden-Farson site formation characteristics are currently indeterminate.

scholarly journals No deal! Sweden cancelled agreement with Elsevier to stand up for Open Science

2019 ◽  
Author(s):  
Cecilia Heyman Widmark ◽  
Göran Hamrin
Keyword(s):  
Open Access ◽  
Time Frame ◽  
Open Science ◽  
Open Access Publishing ◽  
Negative Effects ◽  
Time Period ◽  
Long Time ◽  
Individual Article ◽  
Institute Of Technology ◽  
Short Time

In this talk we highlight some results after the Swedish Bibsam consortium decided to cancel the agreement with scientific publisher Elsevier after 20 years as they couldn’t present a model that met the demands of the consortium. The requirements were immediate open access to all articles published in Elsevier journals by researchers affiliated to participating organisations as well as reading access to all articles in Elsevier’s journals. Bibsam also demanded a sustainable price model that enables a transition to open access publishing. We investigate the effects of this cancellation on Sweden’s largest technical university, the KTH Royal Institute of Technology. Method The study has two themes. First, we analyse the economics in earlier Bibsam-Elsevier agreements and what effects they have had for the budget and purchasing decisions made by the KTH Library. Second, we evaluate the response and the adapted behaviour of KTH researchers in the attempt to see if the cancellation has had severe negative effects for them. Results Our data collection gives an overview over the effects of the cancelled agreement at KTH. In particular, we observe how some of the money saved on the cancellation is used for individual article purchases and alternative services, thus lowering the effect of the cut-off.  During our talk, we will also review some marketing strategies employed at KTH and Swedish libraries for making this cancellation process as smooth as possible. Limitations The short time period that has elapsed after the cancellation makes it difficult to see any long-time trends. The limited time frame also affects the validity of the researchers’ responses. Moreover, it is difficult to tell how the results from a case study from one university can be generalised to a global setting.

scholarly journals A Method for Predicting Efficiency of Perforated Muzzle Brakes

2021 ◽  
Vol 12 (4) ◽  
pp. 29-42
Author(s):  
Marta CZYŻEWSKA ◽  
Radosław TRĘBIŃSKI
Keyword(s):  
Partition Coefficient ◽  
Efficiency Coefficient ◽  
Flow Parameters ◽  
A Value ◽  
Mass Fluxes ◽  
Time Period ◽  
Long Time ◽  
Gasdynamic Flow ◽  
Time Changes ◽  
The Moment

This paper presents a method for predicting a value of a gasdynamic efficiency coefficient for perforated muzzle brakes. The method is based on the interior ballistics modelling for determining gasdynamic flow parameters at the brake inlet and 2D modelling the processes inside the brake with treating vents as circumferential slots. The modelling provides information about the mass flux time changes at the inlet and at the outlet of the brake. Using this information, the mass partition coefficient values and the gasdynamic efficiency coefficient values are calculated. It has been shown that the mass partition coefficient establishes very quickly and it is determined only by the geometry of the brake. The gasdynamic efficiency coefficient establishes after a relatively long time, what demands carrying out calculations for a relatively long time period. However, it has been shown that this problem can be solved by making use of the established ratio of mass fluxes at the outlet and the inlet. So, flow parameters’ values at the inlet are sufficient for determining the gasdynamic efficiency coefficient to the moment of attaining the final value. It has been shown that this value depends on the ballistics and on the vents inclination angle.

Short-Time Tests for Long-Time Endurance

1923 ◽  
Vol 128 (4) ◽  
pp. 264-264
Author(s):  
J. W. Harsch
Keyword(s):  
Long Time ◽  
Short Time

World Economy: Prospects and Barriers for Recovery

2012 ◽  
pp. 61-83 ◽  
Author(s):  
M. Ershov
Keyword(s):  
World Economy ◽  
Western World ◽  
Short Time Period ◽  
Market Segments ◽  
Junk Bonds ◽  
The Past ◽  
Time Period ◽  
The Us ◽  
Global Liquidity ◽  
Short Time

According to the latest forecasts, it will take 10 years for the world economy to get back to “decent shape”. Some more critical estimates suggest that the whole western world will have a “colossal mess” within the next 5–10 years. Regulators of some major countries significantly and over a short time‑period changed their forecasts for the worse which means that uncertainty in the outlook for the future persists. Indeed, the intensive anti‑crisis measures have reduced the severity of the past problems, however the problems themselves have not disappeared. Moreover, some of them have become more intense — the eurocrisis, excessive debts, global liquidity glut against the backdrop of its deficit in some of market segments. As was the case prior to the crisis, derivatives and high‑risk operations with “junk” bonds grow; budget problems — “fiscal cliff” in the US — and other problems worsen. All of the above forces the regulators to take unprecedented (in their scope and nature) steps. Will they be able to tackle the problems which emerge?

Effect of Vial shaking on Loading Time of Epirubicin into Drug-Eluting Bead

2015 ◽  
Vol 5 (3) ◽  
Author(s):  
Kenji Ikeda ◽  
Yusuke Kawamura ◽  
Masahiro Kobayashi ◽  
Taito Fukushima ◽  
Yushi Sorin ◽  
...  
Keyword(s):  
Antitumor Agent ◽  
Loading Rates ◽  
Vortex Mixer ◽  
Long Time ◽  
Group A ◽  
Drug Eluting ◽  
Large Hepatocellular Carcinoma ◽  
Group B ◽  
Time Required ◽  
Short Time

Background: Although DC Bead has been useful in treatment of multiple and large hepatocellular carcinoma, loading time of doxorubicin into the DC Bead takes a long time of 30-120 minutes. Epirubicin is also used as an antitumor agent together with DC Bead, but its loading efficiency was not sufficiently elucidated. Methods: To shorten loading time of epirubicin into DC Bead (100-300µm, 300-500µm, 500-700µm), we examined the following three methods after mixing the drug: (a) let stand in room temperature, (b) agitated for 30 seconds with Vortex mixer, and (c) sonicated for 30 seconds with ultrasonic cleaner. After loading of epirubicin by each method, supernatant concentration for epirubicin was assayed at 5, 10, 30, 60, and 120 minutes. Results: Epirubicin loading rates for small bead (100-300µm) at 5 minutes were 82.9 % in group a, 93.8% in group b, and 79.9 % in group c. Similarly, medium bead (300-500µm), 40.1% in group a, 65.7% in group b and 45.5% in group c, respectively. In large-sized bead (500-700µm), loaded rates of epirubicin were 38.8% in group a, 59.0% in group b and 48.0% in group c. Agitation of mixture of epirubicin and DC Bead with Vortex mixer significantly shortened the loading time, but sonication did not affect the time required. Microscopic examination did not lead to any morphological change of microspheres in all the methods. Conclusions: Short time of agitation with Vortex mixer reduced the necessary time for loading of epirubicin in every standard of DC Bead.

Robust Test Method of TSOP PEMs for Space Application

2019 ◽  
Author(s):  
Yasunobu Iwai ◽  
Koichi Shinozaki ◽  
Daiki Tanaka
Keyword(s):  
Evaluation Method ◽  
Low Cost ◽  
Reliability Evaluation ◽  
Test Method ◽  
Thermal Shock Test ◽  
Space Application ◽  
Space Applications ◽  
Limit Test ◽  
Long Time ◽  
Short Time

Abstract Compared with space parts, consumer parts are highly functional, low cost, compact and lightweight. Therefore, their increased usage in space applications is expected. Prior testing and evaluation on space applicability are necessary because consumer parts do not have quality guarantees for space application [1]. However, in the conventional reliability evaluation method, the test takes a long time, and the problem is that the robustness of the target sample can’t be evaluated in a short time. In this report, we apply to the latest TSOP PEM (Thin Small Outline Package Plastic Encapsulated Microcircuit) an evaluation method that combines preconditioning and HALT (Highly Accelerated Limit Test), which is a test method that causes failures in a short time under very severe environmental conditions. We show that this method can evaluate the robustness of TSOP PEMs including solder connections in a short time. In addition, the validity of this evaluation method for TSOP PEM is shown by comparing with the evaluation results of thermal shock test and life test, which are conventional reliability evaluation methods.

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