Lift and Moment Prediction For an Oscillating Airfoil With a Moving Separation Point

1974 ◽  
Vol 96 (4) ◽  
pp. 372-378 ◽  
Author(s):  
P. V. K. Perumal ◽  
F. Sisto
Keyword(s):  
Flat Plate ◽  
Analytical Method ◽  
Time History ◽  
Experimental Results ◽  
Time Dependent ◽  
Separation Point ◽  
Empirical Knowledge ◽  
Torsional Mode ◽  
History Of ◽  
Dependent Point

An analytical method for predicting the perturbed aerodynamic reactions of a harmonically oscillating flat plate airfoil with time dependent point of separation is presented. It is shown that this method in conjunction with an empirical knowledge of the time history of the separation point can predict stall-flutter. Numerical results are presented and compared with existing theoretical and experimental results with special emphasis on torsional mode of oscillation.

Time Dependent Magnetic Switching in Spin Valve Structures

1995 ◽  
Vol 384 ◽  
Author(s):  
J. B. Restorff ◽  
M. Wun-Fogle ◽  
S. F. Cheng ◽  
K. B. Hathaway
Keyword(s):  
Giant Magnetoresistance ◽  
Spin Valve ◽  
Time History ◽  
Time Dependent ◽  
Si Substrates ◽  
Magnetic Switching ◽  
Magnetic Aftereffect ◽  
Magnetron Sputter Deposition ◽  
History Of ◽  
Time Required

ABSTRACTWe have observed time dependent magnetic switching in spin-valve sandwich structures of Cu/Co/Cu/Fe films grown on silicon and Kapton substrates and Permalloy/Co/Cu/Co films grown on NiO or NiO/CoO coated Si substrates. The giant magnetoresistance (MR) values ranged from 1 to 3 percent at room temperature. The films were grown by DC magnetron sputter deposition. Measurements were made on the time required for the MR to stabilize to about 1 part in 104 after the applied field was incremented. This time depends almost linearly on the amplitude of the timedependent MR change with a slope (time / ΔMR) of 20 000 to 30 000 s. Some samples took as long as 70 s to stabilize. The time dependent effects may be important for devices operating in these regions of the magnetoresistance curve. In addition, measurements were made on the time history of the MR value for a period of 75 s following a step change in the field from saturation. We observed that the time dependent behavior of the MR values of both experiments produced an excellent fit to a function of the form ΔMR(t) = α + β;ln(t) where ɑ and β are constants. This time dependence was consistent with the behavior of the magnetic aftereffect.

Time Dependent FLC Determination Comparison of Different Algorithms to Detect the Onset of Unstable Necking before Fracture

2013 ◽  
Vol 549 ◽  
pp. 397-404 ◽  
Author(s):  
Walter Hotz ◽  
Marion Merklein ◽  
Andreas Kuppert ◽  
Harald Friebe ◽  
Markus Klein
Keyword(s):  
Correlation Coefficient ◽  
Work Group ◽  
Time History ◽  
Time Dependent ◽  
Forming Limit ◽  
Iso Standard ◽  
Modified Method ◽  
History Of ◽  
Forming Limit Curves

The ISO standard 12004-2:2008E for the determination of forming limit curves based on the section method was approved in 2008. About 4 years of measuring experience in different laboratories has shown advantages and weaknesses of the standard and is leading to some minor changes in the specification. In the years from the development of this standard until today a further technical development of the optical measuring devices occurred, so that it is now possible to determine forming limit curves using the time history of the test. This procedure of determination is referred to a time dependent technique and could be the basis of the ISO 12004 part 2 proposal worked out by the work group Erweiterung FLC ISO 12004 of the German group of the IDDRG. This publication recapitulates existing work which was carried out from the IDDRG work group regarding the determination of forming limit curves for sheet metal materials. On one hand known issues with the current section based approach are discussed and on the other hand it deals with a comparison of different algorithms to determine the FLC from the time history of the Nakajima test using strategies to identify the instant of onset of instable necking. The different time dependent algorithms [ utilised are automatically selecting the area where necking is leading to fracture and then analyze the time history of such points using the first or the second time derivative of the true major strain, or of the true thinning strain using methods like: correlation coefficient (modified method based on [2]), gliding correlation coefficient, linear best fit (modified method based on [3]) and gliding difference of mean to median. The resulting experimental FLC points are compared with the results from the section technique described in ISO 12004 part 2 and with the maximum strain values measured in each test. Further a large number of forming limit curves were determined and used for a comparison of these different methods to define the most promising time dependent algorithm, which was selected as a suggestion for the working group defining the new proposed ISO standard 12004 part 2.

The Time History of Axial Force of Soil Nail in Deep Excavation Course

2011 ◽  
Vol 243-249 ◽  
pp. 2259-2265
Author(s):  
Feng Li ◽  
Yuan Cheng Guo ◽  
Gang Shi ◽  
Hui Qian
Keyword(s):  
Axial Force ◽  
Time History ◽  
Time Dependent ◽  
Construction Process ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Soil Nail ◽  
Deformation Curves ◽  
Axial Forces ◽  
History Of

This paper presents a theoretically study on the time-dependent characteristic of soil-nail axial force in the whole construction process of foundation pit. Firstly, the time-varying performance of axial forces of soil nails is analyzed according to the measured lateral deformation curves of pile-anchor and soil-nail composite supporting deep foundation pit. Then combined with a soil rheological model, a time-dependent formula of soil nail axial force is put forward, and the simulated results are compared to the back-analyzed ones. Finally, a formula to predict the time-dependent axial force of soil nail in the whole construction process of foundation pit is established and an example is investigated to validate the method.

EXPERIMENTAL RESULTS AND A SIMPLE THEORY FOR THE EARLY DEFLECTION-TIME HISTORY OF A BALLISTIC FABRIC

2009 ◽  
Author(s):  
Charles E. Anderson ◽  
Sidney Chocron ◽  
Mark Elert ◽  
Michael D. Furnish ◽  
William W. Anderson ◽  
...  
Keyword(s):  
Time History ◽  
Simple Theory ◽  
Experimental Results ◽  
History Of

scholarly journals A Practical Approach to Numerically Predicting a Maneuvering Vessel in Waves Oriented to Maritime Simulator

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Shengke Ni ◽  
Zhengjiang Liu ◽  
Yao Cai ◽  
Teng Zhang
Keyword(s):  
Mathematical Model ◽  
Time History ◽  
Experimental Results ◽  
Periodic Change ◽  
Regular Waves ◽  
Pitch Motion ◽  
Irregular Frequency ◽  
History Of ◽  
Time Required ◽  
The Mathematical Model

To improve the behavioral realism of maritime simulator, the mathematical model of ship heave and pitch motion in regular waves is proposed. To avoid the influence of irregular frequency by two-dimensional Frank source and sink distribution method, the multiparameter conformal mapping method was adopted to solve the hydrodynamic problem of ship’s transverse sections, and then the integration of the hydrodynamic coefficients and the wave exciting forces for the whole ship hull was obtained using the Salvesen–Tuck–Faltinsen (STF) strip method. The Abkowitz model was used for the horizontal maneuverability motion equations, and the ship heave and pitch motion mathematical model in regular waves can be built considering the maneuvering factors. To verify the credibility and applicability of the improved model, the Mariner vessel with a Froude number of 0.2 was taken as the simulation case; when Mariner vessel sails in head waves, the maximum relative error between the calculated results and the experimental results is 23.6% for amplitude response operators of ship heave and pitch motion, and the calculated results and the experimental results have the same trend. When turning maneuvers in regular waves are carried out, the time history of ship pitch and pitch motions in regular waves does not show the sinusoidal periodic change any more, but the time history of heave and pitch motion still possesses periodic change to some extent, at which the period is about the time required for the turning motion to finish a circle. When turning maneuvers are carried out for 3000 seconds, the time required for computer operation is about 487.6 s, and the real-time requirements of maritime simulator are satisfied. Thus, the mathematical model of ship heave and pitch motion established in this paper can be effectively applied to the maritime simulator.

Heat Transfer to Laminar Flow Across a Flat Plate With a Nonsteady Surface Temperature

1961 ◽  
Vol 83 (3) ◽  
pp. 274-279 ◽  
Author(s):  
R. D. Cess
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Surface Temperature ◽  
Flat Plate ◽  
Large Time ◽  
Convection Heat Transfer ◽  
Time History ◽  
Heat Transfer Process ◽  
History Of ◽  
Nonsteady Heat Transfer

Forced convection heat transfer is considered for laminar flow across a flat plate whose surface temperature varies with time. The case analyzed first is that of a step change in surface temperature, and series solutions are obtained which apply for both small and large time. These series results are used to construct an approximate solution which describes the entire time-history of the nonsteady heat-transfer process, and it is found that the results agree closely with an envelope composed of pure transient conduction and steady-state convection solutions. The analysis is then generalized to include any prescribed variation of surface temperature with time.

Time-dependent motions of the cavity formed when a uniform corpuscular flux is incident on the magnetic field of a line current

1968 ◽  
Vol 2 (1) ◽  
pp. 51-57 ◽  
Author(s):  
R. C. Hewson-Browne ◽  
D. N. Burghes
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Time History ◽  
Time Dependent ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Line Current ◽  
History Of ◽  
Steady State Solutions ◽  
The Magnetic Field

This paper concerns the time-dependent motions of the cavity formed when a uniform corpuscular flux is incident on the magnetic field of a line current. The two-dimensional problem is formulated and solved with two particular classes of solutions being given; namely, the steady-state solutions and the time-history of the interaction with a cloud of flux.

Thrust Bearing Characteristics in Impulsively Generated Motion

1977 ◽  
Vol 99 (3) ◽  
pp. 365-368 ◽  
Author(s):  
Cz. M. Rodkiewicz ◽  
V. F. Berka
Keyword(s):  
Numerical Solution ◽  
Constant Velocity ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Time History ◽  
Time Dependent ◽  
Graphical Form ◽  
Lubricating Film ◽  
Pressure Fields ◽  
History Of

Numerical solution is obtained for the case where the fluid within the lubricating film is initially at rest, however, at time zero the infinitely long slider suddenly assumes a constant velocity. Subsequently, the velocity and pressure fields are generated yielding time dependent load capacity. The time history of these quantities is presented in a graphical form.

PROGRAM OF PREDICTION AND MANAGEMENT OF COINTEGED DYNAMIC ECONOMIC PROCESSES BASED ON THE CYBERNETIC APPROACH

2019 ◽  
Author(s):  
Olena Bundak ◽  
Nataliia Zubovetska
Keyword(s):  
Computer Program ◽  
Pair Correlation ◽  
Time History ◽  
Critical Area ◽  
Concrete Object ◽  
Graphic Arts ◽  
Ex Post ◽  
History Of ◽  
Successive Change ◽  
Rms Errors

A method and computer program ConRow, which prognostication of development of the dynamically CPLD economic transients is executed by, is described in the article. Such prognostication of economic processes is very important in the cases when their development can result in undesirable consequences, that to go out in the so-called critical area. Extrapolation in a critical area with the use of information about the conduct of the system at an area, near to it, allows to estimate to the lead through of experiment in the critical area of his consequence. For the imitation of conduct of object the function of review is set on entrance influence. For a concrete object this function can express, for example, dependence of change of level sale from time-history of charges on advertising and set as a numeral row. Statistics as a result of analysis of row are represented in a table, where the level of meaningfulness is set statistician, and also parameters of the handed over criteria. The graphic reflection of information is intended for visualization of analysis. Here represented on the points of graphic arts, the crooked smoothing which are calculated as полиномиальные regressions is added. The best approaching is controlled by sight on the proper graph, and also by minimization of their rms errors. Models of prognostication by sight and as formulas represented on graphic arts, the middle is here determined tailings and their chance is checked up on statistics of signs. After the got models determined also and prognosis values of influences and reviews. Establishing an order models of Сr(p) of co integrate regression is carried out separate custom controls. The coefficient of clay correlation of ruФ shows by itself pair correlation between lines with a successive change in relation to each other on a size to лагу of l = 1, 2, 3 . The program was tested on the example of ex-post prognosis at establishing an integration connection and possibility of prognostication of growth of nominal average monthly settlings on the basis of these statistical indexes of consumer inflation in Ukraine.

Nitrate and chloride formation in chloramination

1994 ◽  
Vol 30 (9) ◽  
pp. 101-110
Author(s):  
V. Diyamandoglu
Keyword(s):  
Kinetic Model ◽  
Analytical Method ◽  
Kinetic Data ◽  
Experimental Results ◽  
Mass Balances ◽  
Time Profiles ◽  
Slow Decay ◽  
Concentration Time ◽  
End Products ◽  
Chlorine Residuals

The formation of nitrate and chloride as end-products of chloramination (combined chlorination) was investigated at pH ranging between 6.9 and 9.6 at 25°C. The experimental results comprised concentration-time profiles of combined chlorine residuals along with nitrate and chloride. Nitrite, if present, was always below the detectibility limit of the analytical method used (25 ppb). Mass balances on chlorine species depicted that chloride formed during the slow decay of combined chlorine residuals does not account for all the chlorine lost. This substantiates the formation of other reaction end-products which are yet to be identified. A kinetic model for chloramination is proposed based on the kinetic data obtained in this study.

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