scholarly journals Airplane Vortices Evolution Near Ground

2021 ◽  
Vol 11 (1) ◽  
pp. 457
Author(s):  
Josep M. Duró ◽  
Josep M. Bergadà
Keyword(s):  
Complex Potential ◽  
Velocity Potential ◽  
Minimum Time ◽  
Atmospheric Conditions ◽  
Potential Equation ◽  
Vortical Structures ◽  
Pressure Fields ◽  
Flow Circulation ◽  
Time Required ◽  
Over Time

Airport traffic around the world has sharply increased over the years; as a result, airports need to be enlarged and the landing or taking off times between two consecutive airplanes must be reduced. To precisely determine the minimum time required between two consecutive airplanes, it is essential to understand the main physical characteristics of the vortices generated under airplanes’ wings and their evolution under different atmospheric conditions. In the present paper, such information is obtained through the complex potential equation of a vortex together with the potential Bernoulli equation. The process starts with the characteristic complex potential equation, which is simplified to find the velocity potential function. Then, the temporal movement of the vortices’ central core, the velocity and pressure fields around the vortical structures and the effect of the crosswind on the vortices’ displacement, velocity and pressure fields are obtained. The paper shows how optimizing the process of measuring and calculating the vortices’ behavior could save a certain amount of time between airplanes, therefore increasing airport throughput. This paper introduces a potential flow method, which is coupled with the temporal variation of the flow circulation, to predict the vortices’ behavior and movement over time. The inclusion of circulation decay over time is employed to simulate the viscosity effect over the vortical structures. The in-house code generates results in less than one minute and needs to be seen as a tool to determine, for each airport and crosswind condition, the minimum time needed between two consecutive airplanes.

scholarly journals Minimum time required to detect population trends: the need for long-term monitoring programs

2017 ◽  
Author(s):  
Easton R White
Keyword(s):  
Time Series ◽  
Statistical Power ◽  
Time Series Data ◽  
Conservation Status ◽  
Monitoring Program ◽  
Minimum Time ◽  
Series Data ◽  
Series Length ◽  
Time Required

Long-term time series are necessary to better understand population dynamics, assess species' conservation status, and make management decisions. However, population data are often expensive, requiring a lot of time and resources. When is a population time series long enough to address a question of interest? We determine the minimum time series length required to detect significant increases or decreases in population abundance. To address this question, we use simulation methods and examine 878 populations of vertebrate species. Here we show that 15-20 years of continuous monitoring are required in order to achieve a high level of statistical power. For both simulations and the time series data, the minimum time required depends on trend strength, population variability, and temporal autocorrelation. These results point to the importance of sampling populations over long periods of time. We argue that statistical power needs to be considered in monitoring program design and evaluation. Time series less than 15-20 years are likely underpowered and potentially misleading.

scholarly journals Instruments and Methods: The USA CRREL Drill for Thermal Coring in Ice

1969 ◽  
Vol 8 (53) ◽  
pp. 311-314 ◽  
Author(s):  
Herbert T. Ueda ◽  
Donald E. Garfield
Keyword(s):  
Minimum Time ◽  
Vacuum System ◽  
Polar Ice ◽  
Electrical Cable ◽  
Additional Equipment ◽  
Melt Water ◽  
The Usa ◽  
Time Required ◽  
Electrothermal Unit

The USA CRREL drill is an 80-kg, electrothermal unit designed for continuous coring in temperate or polar ice or snow. The drill melts a hole approximately 16.3 cm in diameter and retrieves a core approximately 12.2 cm in diameter at rates from 1.9 m h−1 in −28°C ice to 2.3 m h−1 in temperate ice. The melt water formed is removed by a vacuum system and stored in a tank. Additional equipment includes 450 m of armored electrical cable, a hoist, a 6.7-m tower and a gasoline generator. The minimum time required to drill a 450-m hole is 435 h. All of the equipment has been designed to be assembled and operated by two men and has a gross shipping weight of 1180 kg.

Vortex street impinging upon an elliptical leading edge

1990 ◽  
Vol 211 ◽  
pp. 211-242 ◽  
Author(s):  
Ismet Gursul ◽  
Donald Rockwell
Keyword(s):  
Velocity Field ◽  
Flow Visualization ◽  
Pressure Field ◽  
Leading Edge ◽  
Vortex Street ◽  
Transverse Displacement ◽  
Vorticity Field ◽  
Measured Velocity ◽  
Vortical Structures ◽  
Pressure Fields

The interaction of a Kármán vortex street with an elliptical edge is investigated experimentally. Basic types of interaction, as a function of scale and transverse displacement of the incident vortex street, are revealed using flow visualization. Unsteady pressure fields induced by these interactions are measured by a phase-averaging technique and correlated with the visualized flow patterns for basic classes of interactions.For a generic vortex–edge interaction, measurements of the phase-averaged velocity field allow construction of streamlines and vorticity contours showing the details of the interaction, including distortion of the vortical structures near the edge. The pressure field is calculated from the measured velocity field and interpreted in relation to the vortical structures.Simulation of flow visualization using the measured velocity field demonstrates possible misinterpretations related to the underlying vorticity field.

ITA Expansion, Time, and Costs

2019 ◽  
pp. 113-140
Author(s):  
Susan D. Franck
Keyword(s):  
Missing Data ◽  
Dispute Resolution ◽  
Diffusion Of Innovations ◽  
Sociological Perspective ◽  
Descriptive Data ◽  
Expansion Time ◽  
Legal Costs ◽  
Potential Impact ◽  
Time Required ◽  
Over Time

Chapter 4 initially provides data about the growth of ITA as well as offering a series of frames against which to understand its evolution, including a sociological perspective analyzing changes in ITA’s caseload against Professor Everett’s theory of diffusion of innovations. It next explores other elements of time, namely case length and deliberative delays, by offering descriptive data and testing whether case length has reliably increased over time or whether resolution times vary on the basis of institutions resolving disputes. It then turns to exploring temporal elements related to bifurcation and separate opinions. After providing an explanation of the fiscal costs data particularly related to parties’ legal costs as well as tribunal costs and expenses (and conducting a variety of tests to explore the potential impact of missing data), the last section identifies the reliable relationship between the costs of dispute resolution and the time required to resolve the dispute.

Minimum time required for assessing step variability during running at submaximal velocities

2018 ◽  
Vol 80 ◽  
pp. 186-195 ◽  
Author(s):  
Felipe García-Pinillos ◽  
Pedro A. Latorre-Román ◽  
Rodrigo Ramírez-Campillo ◽  
Juan A. Párraga-Montilla ◽  
Luis E. Roche-Seruendo
Keyword(s):  
Minimum Time ◽  
Time Required

Fluid Transients in a Pipeline With One Open End

2008 ◽  
Author(s):  
Robert A. Leishear
Keyword(s):  
Water Hammer ◽  
Atmospheric Conditions ◽  
Air Entrapment ◽  
Complex Interactions ◽  
Fluid Transients ◽  
Pipe Line ◽  
Multi Phase Flow ◽  
Time Required ◽  
Multi Phase ◽  
Transparent Tube

Water hammer during multi-phase flow is rather complex, but in some cases an upper limit to the pressure surge magnitude during water hammer can be estimated. In the case considered here, a two mile long pipeline with a single high point was permitted to partially drain. Due to gravitational effects, air bubbles up through the pipe line to its highest point, but the time required for air to reach the top of the pipe is rather long. Consequently, some transients caused by valve operations are affected by air entrapment and some are not. The intent of this research was to investigate the complex interactions between air, water vapor, and liquid during water hammer in a long pipe with one end of the pipe open to atmospheric conditions. To understand the system dynamics, experimental data was obtained from a long pipeline with an open end and also from a short, transparent tube. Transient calculations were performed for valve closures and pump operations as applicable. The limitations of available calculation techniques were considered in detail.

Target Detection, Rifle Marksmanship, and Mood during Three Hours of Simulated Sentry Duty

1989 ◽  
Vol 33 (20) ◽  
pp. 1414-1418 ◽  
Author(s):  
Richard F. Johnson ◽  
Donna J. McMenemy
Keyword(s):  
Target Detection ◽  
Rating Scale ◽  
Test Session ◽  
Profile Of Mood States ◽  
Detection Time ◽  
Target Speed ◽  
The Subject ◽  
Time Required ◽  
Duty Time ◽  
Over Time

The purpose of this study was to evaluate the effects of sentry duty time on the soldier's speed of detection of visually presented targets, his ability to hit targets (rifle marksmanship), and his mood. Prior to the test day, each of eight subjects was given five days of training on the Weaponeer Rifle Marksmanship Simulator and was familiarized with the targets to be presented during testing. The test session lasted three hours, during which time the subject assumed a standing foxhole position and monitored the target scene of the Weaponeer. The Weaponeer M16A1 modified rifle lay next to the subject at chest height. When a pop-up target appeared, the subject pressed a telegraph key, lifted the rifle, aimed, and fired at the target. Speed of target detection was measured in terms of the time required by the subject to press the telegraph key in response to the presentation of the target. Marksmanship was measured in terms of number of targets hit. Target detection time and rifle marksmanship were averaged every 30 minutes. At the end of the test session, the subject completed the Profile of Mood States rating scale. The results showed that target detection time deteriorated with time on sentry duty; impairments were not evident within the first hour but were clearly evident by 1.5 hours. Marksmanship remained constant over time; soldiers were just as accurate in hitting the targets at the end of the 3 hours of sentry duty as they were at the beginning. Whereas the soldier's predominant mood during baseline practice sessions was one of vigor, during sentry duty the predominant mood was one of fatigue. The results of this study suggest that sentry duty performance may be optimized if it is limited to one hour or less.

scholarly journals Need for teleconsultation among the emergency medicine and critical care personnel during pre-hospital transport in a tertiary care unit

2017 ◽  
Vol 4 (1) ◽  
pp. 176
Author(s):  
V. Karunai Kadhir ◽  
T. Hemalatha ◽  
V. P. Chandrasekaran
Keyword(s):  
Emergency Medicine ◽  
Treatment Guidelines ◽  
Improve Patient Safety ◽  
Prehospital Care ◽  
Tertiary Care ◽  
Minimum Time ◽  
Care Hospital ◽  
Cross Sectional ◽  
Significant Difference ◽  
Time Required

Background: Time being the most crucial factors in emergency medicine, teleconsultation enables patient assessment by specialists, immediate reception of appropriate treatment guidelines until the patient's arrival at hospital.Methods: Our study evaluated the need for teleconsultation among the emergency physicians (EP) and emergency technicians (ET) in a tertiary care hospital. Cross-sectional study conducted in Department of Emergency Medicine, a tertiary care setting. Pretested semi-structured questionnaire was given to EP and ET. Various parameters like the need for teleconsultation, the minimum time required for EMS (emergency medical services) to arrive at the scene and to the hospital, effectiveness of teleconsultation in prehospital care were evaluated.Results: SPSS version 18.0 was used. 24 EP and 36 ET participated in the study. The minimum time required for the EMS to arrive at the scene and then to hospital was calculated indirectly to be > 30 min. There was a significant difference among the EP an ET in interpreting common emergency condition p = 0.029 and criticality assessment p=0.035.The training of EMS staffs was adequate. Both EP and ET were able to adhere recent guidelines during prehospital transport. All the study participants (100%) felt the need for teleconsultation which would improve the patient management during the prehospital period.Conclusions: Teleconsultation has the potential to improve patient safety and quality of treatment in a prehospital setting and should be further evaluated.  

scholarly journals A Protocol to Quantify the Reactivity of Carbonate Lime for Horticultural Substrates

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1124E-1125
Author(s):  
Jinsheng Huang ◽  
Paul R. Fisher ◽  
William R. Argo
Keyword(s):  
Particle Size ◽  
Reaction Rates ◽  
Rapid Screening ◽  
Reactivity Index ◽  
Analytical Test ◽  
Horticultural Practice ◽  
Ph Level ◽  
Time Required ◽  
Lime Reactivity ◽  
Over Time

Lime sources vary in their reactivity depending on particle size, surface area and crystalline structure, and chemical composition. Current horticultural practice for testing lime reactivity and the appropriate lime rate is through batch trials where lime is incorporated into growing media. Our objective was to test a laboratory approach that would provide a rapid analytical test on reactivity of lime sources, and could eventually be applied to measuring unreacted (residual) lime in container media. Four moles HCl was added to a lime sample, and the volume of CO2 released over time was measured in a burette. Three lime types were tested, including reagent grade CaCO3, and two pulverized dolomitic limestones used in horticultural media. 100% of CaCO3 reacted in less than a minute after acid addition, whereas only 79.8% and 49.5% of the two commercial lime samples had reacted after 10 minutes. The time required for 50% of the two commercial lime samples to react was 5 and 10 minutes, respectively, whereas it took 20 and 60 minutes, respectively, for 95% neutralization. Reaction rates in the laboratory test correlated with the time required to achieve a stable pH level when limes were incorporated into a peat substrate. The reagent-grade CaCO3 raised pH more rapidly (within 7 days) and to a higher level (maximum pH 7.5 at 9 g of lime per liter of peat) compared with the dolomitic lime sources. It may be possible to establish a lime reactivity index, for example, based on CO2 release after 10 minutes, and thereby provide a rapid screening of limes. Further gasometric analysis of lime types used in horticultural substrates is therefore needed.

scholarly journals Adaptive SIR model for propagation of SARS-CoV-2 in Brazil

2020 ◽  
Author(s):  
I. F. F. dos Santos ◽  
G. M. A. Almeida ◽  
F. A. B. F. de Moura
Keyword(s):  
Sir Model ◽  
Virus Propagation ◽  
Epidemic Dynamics ◽  
Time Required ◽  
Near Future ◽  
Official Data ◽  
Over Time

Abstract We study the spreading of SARS-CoV-2 in Brazil based on official data available since March 22, 2020. The calculations are based on an adaptive susceptible-infected-removed (SIR) model featuring dynamical recuperation and propagation rates and can reproduce the number of confirmed cases over time with less than $5\%$ error. Furthermore, it is possible to predict the epidemic progression in the near future and we go on to estimate the time required to stabilize the virus propagation. The model is also proved to be accurate for analyzing the epidemic dynamics in other countries.

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