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1

Two opposite hysteresis curves in semiconductors with mobile dopants

NASA Astrophysics Data System (ADS)

Semiconductors with mobile dopants (SMDs), which are distinct from conventional semiconductors, exhibit hysteretic current-voltage curves. The fundamental feature of this hysteresis curve is that it exhibits two oppositely rotating directions, whose origin is not clarified yet. Here, we investigate microscopic origin of the two types of curves and show that they result from the spatial inhomogeneity of the mobile dopant distribution in the SMD. In particular, we observed an abnormal modulation of the electronic energy band due to mobile dopants; lower (higher) density of dopants near a metal-semiconductor interface lead to higher (lower) conductance, whereas the conventional ionic models predict the reverse behaviors.

Sung Lee, Jae; Buhm Lee, Shin; Kahng, Byungnam; Won Noh, Tae

2013-06-01

2

NASA Astrophysics Data System (ADS)

The influence of power semiconductor characteristic in Pulse-width-modulation (PWM) inverter on the magnetic hysteresis curve in silicon steel is discussed through the measured magnetic hysteresis curves. The magnetic hysteresis curve of PWM inverter-fed silicon steel has a lot of minor loops as closed loops and open loops, which make an influence on the iron loss. Two shapes of minor loops are found to be caused by the voltage shifts and they are derived from the on-voltage of the semiconductors in PWM inverter circuit. Therefore, it is concluded that the power-semiconductor characteristic in PWM inverter makes an influence on the magnetic hysteresis curve in silicon steel.

Fujisaki, Keisuke; Liu, Sungju

2014-05-01

3

Life prediction of stainless steels by cyclic and stable hysteresis curves

This study develops an analytical expression to describe the cyclic stress?strain curve obtained from a series of fully?reversed fatigue tests. A set of stress?strain relationships is proposed to simulate the tensile branch of the stable hysteresis loop. The complete shape of the stable hysteresis loop is then constructed and the associated theoretical plastic work calculated by integrating the area within

2005-01-01

4

Hysteresis and uncertainty in soil water-retention curve parameters

Accurate estimates of soil hydraulic parameters representing wetting and drying paths are required for predicting hydraulic and mechanical responses in a large number of applications. A comprehensive suite of laboratory experiments was conducted to measure hysteretic soil-water characteristic curves (SWCCs) representing a wide range of soil types. Results were used to quantitatively assess differences and uncertainty in three simplifications frequently adopted to estimate wetting-path SWCC parameters from more easily measured drying curves. They are the following: (1) ?w=2?d, (2) nw=nd, and (3) ?ws=?ds, where ?, n, and ?s are fitting parameters entering van Genuchten’s commonly adopted SWCC model, and the superscripts w and d indicate wetting and drying paths, respectively. The average ratio ?w/?d for the data set was 2.24±1.25. Nominally cohesive soils had a lower ?w/?d ratio (1.73±0.94) than nominally cohesionless soils (3.14±1.27). The average nw/nd ratio was 1.01±0.11 with no significant dependency on soil type, thus confirming the nw=nd simplification for a wider range of soil types than previously available. Water content at zero suction during wetting (?ws) was consistently less than during drying (?ds) owing to air entrapment. The ?ws/?ds ratio averaged 0.85±0.10 and was comparable for nominally cohesive (0.87±0.11) and cohesionless (0.81±0.08) soils. Regression statistics are provided to quantitatively account for uncertainty in estimating hysteretic retention curves. Practical consequences are demonstrated for two case studies.

Likos, William J.; Lu, Ning; Godt, Jonathan W.

2014-01-01

5

NASA Astrophysics Data System (ADS)

In this paper, we present a study of detecting the hysteresis effect in strain-stress curve of carbon fiber reinforced materials by Fiber Bragg Grating technology. By calculating the dissipative energy density contoured by hysteresis loops, this method can be further applied in detecting the cracks and fatigue of carbon fiber reinforced laminates. In contrast to the traditional sensors, such FBG sensors have numerous merits, such as small size, immunity to Electromagnetic Interference and easy installation into the carbon fiber reinforced laminates. This method can also be extended into monitoring other materials which also exhibit hysteresis effects in their strain-stress curves.

Zhang, Hongtao; Ghandehari, Masoud; Sidelev, Alexey; Bazhanski, Ruslan; Wang, Pengfei; Xie, Jing; Zou, Jilin; Lui, Engui; Li, David; Fang, Fang; Cui, Hong-Liang; Wang, Xingwei

2011-05-01

6

Vapour liquid coexisting curves and hysteresis of simple adsorbate in complex porous systems

NASA Astrophysics Data System (ADS)

A unified approach for simulation of the vapour-liquid coexisting curves on phase diagrams and hysteresis phenomena for simple adsorbates in various type porous adsorbents was developed on the basis of the lattice-gas model. The ideas of this model in complex porous systems were used twice: for a construction of the over-molecular structure for high-dispersed bodies and for a description of the molecular distribution within the complex porous space. The supramolecular structure of these systems is modelled by sections with a simple regular geometry (slit-like, cylindrical and spherical) with additional inclusion of junctions between different pore sections. At the description of the adsorbate distribution, the lateral interactions between the fluidic molecules were included through the quasi-chemical approximation (QCA) that takes into account direct pair correlations between interacting molecules. The knowledge of phase diagrams allows improving a description of the adsorption hysteresis phenomena. The lattice-gas model enables explaining the experimental data for MCM-41 like sample in which the hysteresis is absent, when the pore size is narrowed more than ˜4 nm.

Tovbin, Yu. K.; Yeremich, D. V.; Zhidkova, L. K.

2005-10-01

7

NASA Astrophysics Data System (ADS)

The crossing in magnetic levitation force-gap hysteresis curve of melt high-temperature superconductor (HTS) vs. NdFeB permanent magnet (PM) was experimentally studied. One HTS bulk and PM was used in the experiments. Four experimental methods were employed combining of high/low speed of movement of PM with/without heat insulation materials (HIM) enclosed respectively. Experimental results show that crossing of the levitation force-gap curve is related to experimental methods. A crossing occurs in the magnetic force-gap curve while the PM moves approaching to and departing from the sample with high or low speed of movement without HIM enclosed. When the PM is enclosed with HIM during the measurement procedures, there is no crossing in the force-gap curve no matter high speed or low speed of movement of the PM. It was found experimentally that, with the increase of the moving speed of the PM, the maximum magnitude of levitation force of the HTS increases also. The results are interpreted based on Maxwell theories and flux flow-creep models of HTS.

Lu, Yiyun; Qin, Yujie; Dang, Qiaohong; Wang, Jiasu

2010-12-01

8

25. VIEW TO EAST; SHOWS CURVE IN SOUTH RETAINING WALL ...

25. VIEW TO EAST; SHOWS CURVE IN SOUTH RETAINING WALL AND SIDEWALK ELECTROLIER ON ALISO STREET (Asano) - Los Angeles Union Passenger Terminal, Mail, Baggage, & Express Building, 800 North Alameda Street, Los Angeles, Los Angeles County, CA

9

60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS ...

60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS AND FLOATING BARGE IN BACKGROUND, February 16, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

10

View to southwest along bridge alignment, showing reverse curve from ...

View to southwest along bridge alignment, showing reverse curve from near deck level; Southern Pacific Railroad track passing beneath bridge; Western Pacific Railroad track out of sight behind bridge; photographer unknown; 1933 photo from collection of Office of Structures Maintenance, California Department of Transportation, Sacramento - Carroll Overhead Bridge, Altamont Pass Road, Livermore, Alameda County, CA

11

Measurements of the frequency shift versus distance in noncontact atomic force microscopy (NC-AFM) allow measurements of the force gradient between the oscillating tip and a surface (force-spectroscopy measurements). When nonconservative forces act between the tip apex and the surface the oscillation amplitude is damped. The dissipation is caused by bistabilities in the potential energy surface of the tip-sample system, and the process can be understood as a hysteresis of forces between approach and retraction of the tip. In this paper, we present the direct measurement of the whole hysteresis loop in force-spectroscopy curves at 77 K on the PTCDA/Ag/Si(111) ?3 × ?3 surface by means of a tuning-fork-based NC-AFM with an oscillation amplitude smaller than the distance range of the hysteresis loop. The hysteresis effect is caused by the making and breaking of a bond between PTCDA molecules on the surface and a PTCDA molecule at the tip. The corresponding energy loss was determined to be 0.57 eV by evaluation of the force-distance curves upon approach and retraction. Furthermore, a second dissipation process was identified through the damping of the oscillation while the molecule on the tip is in contact with the surface. This dissipation process occurs mainly during the retraction of the tip. It reaches a maximum value of about 0.22 eV/cycle. PMID:22496993

Lange, Manfred; van Vörden, Dennis; Möller, Rolf

2012-01-01

12

Summary Measurements of the frequency shift versus distance in noncontact atomic force microscopy (NC-AFM) allow measurements of the force gradient between the oscillating tip and a surface (force-spectroscopy measurements). When nonconservative forces act between the tip apex and the surface the oscillation amplitude is damped. The dissipation is caused by bistabilities in the potential energy surface of the tip–sample system, and the process can be understood as a hysteresis of forces between approach and retraction of the tip. In this paper, we present the direct measurement of the whole hysteresis loop in force-spectroscopy curves at 77 K on the PTCDA/Ag/Si(111) ?3 × ?3 surface by means of a tuning-fork-based NC-AFM with an oscillation amplitude smaller than the distance range of the hysteresis loop. The hysteresis effect is caused by the making and breaking of a bond between PTCDA molecules on the surface and a PTCDA molecule at the tip. The corresponding energy loss was determined to be 0.57 eV by evaluation of the force–distance curves upon approach and retraction. Furthermore, a second dissipation process was identified through the damping of the oscillation while the molecule on the tip is in contact with the surface. This dissipation process occurs mainly during the retraction of the tip. It reaches a maximum value of about 0.22 eV/cycle.

van Vorden, Dennis; Moller, Rolf

2012-01-01

13

Appearance of magnetization jumps in magnetic hysteresis curves in spinel oxide FeV2O4

NASA Astrophysics Data System (ADS)

We report the appearance of magnetization jumps in the magnetic hysteresis curves of the spinel oxide FeV2O4, in which two different magnetic transition ions appeared, both of them having orbital degrees of freedom. The spin-glass-like transition was observed from ac magnetic susceptibilities and the transition temperature was estimated to be Tg=85.5 K. The magnetization jumps appear below 90 K at B=0. In addition, jumps at B=+/-1.2 T appear below 4.6 K. The magnetization jumps at B=0 may be correlated with spin-glass-like behaviors.

Nishihara, Sadafumi; Doi, Wataru; Ishibashi, Hiroki; Hosokoshi, Yuko; Ren, Xiao-Ming; Mori, Shigeo

2010-05-01

14

Quantum Hydrodynamic Simulation of Hysteresis in the Resonant Tunneling Diode

Hysteresis in the current-voltage curve of a resonant tunneling diode is simulated and analyzed in the quantum hydrodynamic (QHD) model for semiconductor devices. The simulations are the first to show hysteresis in the QHD equations and to confirm that bistability is an intrinsic property of the resonant tunneling diode. Hysteresis appears in many settings in fluid dynamics. The simulations presented

Zhangxin Chen; Bernardo Cockburn; Carl L. Gardner; Joseph W. Jerome

1995-01-01

15

Thermohaline circulation hysteresis: A model intercomparison

We present results from an intercomparison of 11 different climate models of intermediate complexity, in which the North Atlantic Ocean was subjected to slowly varying changes in freshwater input. All models show a characteristic hysteresis response of the thermohaline circulation to the freshwater forcing; which can be explained by Stommel's salt advection feedback. The width of the hysteresis curves varies

Stefan Rahmstorf; Michel Crucifix; Andrey Ganopolski; Hugues Goosse; Igor Kamenkovich; Reto Knutti; Gerrit Lohmann; Robert Marsh; Lawrence A. Mysak; Zhaomin Wang; Andrew J. Weaver

2005-01-01

16

We investigated if the transcriptional response of Salmonella Typhimurium to temperature and acid variations was hysteretic, i.e. whether the transcriptional regulation caused by environmental stimuli showed memory and remained after the stimuli ceased. The transcriptional activity of non-replicating stationary phase cells of S. Typhimurium caused by the exposure to 45°C and to pH 5 for 30 min was monitored by microarray hybridizations at the end of the treatment period as well as immediately and 30 minutes after conditions were set back to their initial values, 25°C and pH 7. One hundred and two out of 120 up-regulated genes during the heat shock remained up-regulated 30 minutes after the temperature was set back to 25°C, while only 86 out of 293 down regulated genes remained down regulated 30 minutes after the heat shock ceased. Thus, the majority of the induced genes exhibited hysteresis, i.e., they remained up-regulated after the environmental stress ceased. At 25°C the transcriptional regulation of genes encoding for heat shock proteins was determined by the previous environment. Gene networks constructed with up-regulated genes were significantly more modular than those of down-regulated genes, implying that down-regulation was significantly less synchronized than up-regulation. The hysteretic transcriptional response to heat shock was accompanied by higher resistance to inactivation at 50°C as well as cross-resistance to inactivation at pH 3; however, growth rates and lag times at 43°C and at pH 4.5 were not affected. The exposure to pH 5 only caused up-regulation of 12 genes and this response was neither hysteretic nor accompanied of increased resistance to inactivation conditions. Cellular memory at the transcriptional level may represent a mechanism of adaptation to the environment and a deterministic source of variability in gene regulation.

Pin, Carmen; Hansen, Trine; Munoz-Cuevas, Marina; de Jonge, Rob; Rosenkrantz, Jesper T.; Lofstrom, Charlotta; Aarts, Henk; Olsen, John E.

2012-01-01

17

NASA Astrophysics Data System (ADS)

The influence of applied tensile stress on the hysteresis curve and domain structure in conventional (1?1?0)[0?0?1] Fe–3%Si steel, cut parallel to the rolling direction, is studied on samples with different grain sizes. Quasistatic hysteresis loops under tensile stresses up to 70 MPa were measured. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of stress. It is shown that for stresses exceeding 5–10 MPa the bulk hysteresis loop can be described with good accuracy by the action of an effective field, which is the product of a function of stress and a function of magnetization. The function of stress is approximately linear with a slope of one. Except for the sample with the smallest grains, the function of magnetization is linear in the magnetization range ±1.2–1.5 T, i.e. it has a typical demagnetizing field shape. Domain observation reveals that the effective field is caused by the demagnetizing fields occurring at grain boundaries and at the sheet surface due to the removal of closure domains transverse to the rolling direction by the tensile stress. The closure structure reappears at higher fields. Another indirect indication of demagnetizing fields is the fact that the hysteresis losses drop continuously with stress and changes in the coercive force are small. The effective field of the sample with the smallest grains increases most nonlinearly with stress similar to the behaviour obtained for non-oriented material.

Perevertov, O.; Schäfer, R.

2014-05-01

18

NSDL National Science Digital Library

You can choose from three values for disorder of the system and select a goal for the external magnetic field by clicking in a "control bar" area. Output graphs show qualitative information, but no numbers. A brief explanation of the physics of hysteresis is provided and the java source code can be downloaded.

Houle, Paul

19

Temperature Dependent Hysteresis Study in Polyvinylidene Fluoride.

National Technical Information Service (NTIS)

An experimental study of temperature dependent ferroelectric hysteresis phenomena of polyvinylidene fluoride is presented. The temperature dependence of the remanent polarization and coercive field was measured from saturated ferroelectric hysteresis curv...

R. B. Olsen J. C. Hicks M. G. Broadhurst G. T. Davis

1983-01-01

20

Hysteresis in weak ferromagnets

NASA Astrophysics Data System (ADS)

Magnetic hysteresis is studied in the orthoferrites ErFeO3 and TmFeO3 using the single crystal samples of millimeter dimensions. It is shown that in both materials one observes a temperature transition manifesting itself through the temperature hysteresis of the magnetic moment and a peculiar temperature evolution of the field hysteresis loop shapes near this transition. Experiments rule out the hypothesis that the ordering of the orthoferrite's rare earth magnetic moments plays an important role in these phenomena. The hysteresis curves can be explained by a few-domain magnetic state of the samples that results from the weak ferromagnetism of the orthoferrites. The phenomenon is generic for weak ferromagnets with temperature dependent magnetization. A large characteristic magnetic length makes the behavior of the relatively big samples analogous to that observed in the nano-size samples of strong ferromagnets.

Bazaliy, Ya. B.; Tsymbal, L. T.; Kakazei, G. N.; Vasiliev, S. V.

2011-03-01

21

BACKGROUND Endoscopic vein harvest (EVH) is the US standard of care for CABG but recent comparisons to open harvest suggest that conduit quality and outcomes may be compromised. To test the hypothesis that problems with EVH may relate to its learning curve and conduit quality, we analyzed the quality and early function of conduits procured by technicians with varying EVH experience. METHODS EVH was performed during CABG by “experienced” (>900 cases, n=55 patients) vs. “novice” (<100 cases, n=30 patients) technicians. Afterwards, conduits were and examined for vascular injury using optical coherence tomography (OCT), with segments identified as injured further examined for gene expression using a tissue injury array. Conduit diameter was measured intra- and postoperatively (day 5 and 6 months) using OCT and Computed-Tomography angiography. RESULTS EVH performed by novice harvesters resulted in increased number of discrete graft injuries and higher expression of tissue injury genes. Regression analysis revealed an association between shear stress and early dilation (positive remodeling) (R2 =0.48, p <0.01). Injured veins showed blunted positive remodeling at 5 days and a greater degree of late lumen loss at 6 months. CONCLUSION Under normal conditions, intraluminal shear stress leads vein grafts to develop positive remodeling over the first postoperative week. Injury to conduits, a frequent sequela of the learning curve for EVH, was a predictor of early graft failure, blunted positive remodeling and greater negative remodeling. Given the ongoing annual volume of EVH cases, rigorous monitoring of the learning curve represents an important and unrecognized public health issue.

Kiani, Soroosh; Desai, Pranjal H.; Thirumvalavan, Nannan; Kurian, Dinesh John; Flynn, Mary Margaret; Zhao, XiaoQing

2011-01-01

22

AN Lyn: a multiperiodic Delta Scuti star showing atypical light curves

NASA Astrophysics Data System (ADS)

We have collected simultaneous uvby photometry of the Delta Sct star AN Lyn during the years 1995 and 1996 at the observatories of San Pedro Mertir, Mexico and Sierra Nevada, Spain. Firstly, analysis of frequencies of our 1995's data set was carried out using the Discrete Fourier Transform method, as described in Lopez de Coca et al. (1984), to the filter v. The periodograms showed a principal peak at v1 ~ 10.1756 c/d, very close to that frequency which corresponds to the period P ~0.0982739 d derived from earlier works. After prewhitening for v1 we found a second peak at 20.3525 c/d that corresponds to 2*v1. When these two frequencies are subtracted from the light curves, the periodograms show some peaks that reveal that additional frequencies are remaining in the spectra at very low amplitude as compared with the amplitude of the main peak (less than 5%).

Rodriguez, E.; Gonzalez-Bedolla, S. F.; Rolland, A.; Costa, V.; Lopez-Gonzalez, M. J.; Lopez de Coca, P.

1997-07-01

23

Congruency-based hysteresis models for transient simulation

We describe a history-dependent (non-Preisach) hysteresis model based on direct use of experimental first-order reversal curves. We propose that any second or higher order reversal curve can be constructed by using internal segments of the first-order reversal curves, and show that particular transplants (segments with required overall dimensions ?H,?B) can always be found in both the B and H directions

Sergey E. Zirka; Yury I. Moroz; Philip Marketos; Anthony J. Moses

2004-01-01

24

NASA Technical Reports Server (NTRS)

The Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS) will be deployed from the Space Shuttle and used as a target for a Shuttle-mounted laser. It will be a cylindrical satellite with several corner cube reflectors on the ends. The center of mass of the cylinder will be near one end, and aerodynamic torques will tend to align the axis of the cylinder with the spacecraft velocity vector. Magnetic hysteresis rods will be used to provide passive despin and oscillation-damping torques on the cylinder. The behavior of the hysteresis rods depends critically on the 'B/H' curves for the combination of materials and rod length-to-diameter ratio ('l-over-d'). These curves are qualitatively described in most Physics textbooks in terms of major and minor 'hysteresis loops'. Mathematical modeling of the functional relationship between B and H is very difficult. In this paper, the physics involved is not addressed, but an algorithm is developed which provides a close approximation to empirically determined data with a few simple equations suitable for use in computer simulations.

Flatley, Thomas W.; Henretty, Debra A.

1995-01-01

25

Synchronous neural networks of nonlinear threshold elements with hysteresis.

We use Hoffmann's suggestion [Hoffmann, G. W. (1986) J. Theor. Biol. 122, 33-67] of hysteresis in a single neuron level and determine its consequences in a synchronous network made of such neurons. We show that the overall retrieval ability in the presence of noise and the memory capacity of the network in the present model are better than in conventional models without such hysteresis. Second-order interaction further improves the retrieval ability of the network and causes hysteresis in the retrieval-noise curve for any arbitrary width of the bistable region. The convergence rate is increased by the hysteresis at high noise levels but is reduced by the hysteresis at low noise levels. Explicit formulae are given for calculations of average final convergence and noise threshold as functions of the width of the bistable region. There is neurophysiological evidence for hysteresis in single neurons, and we propose optical implementations of the present model by using ZnSe interference filters to test the predictions of the theory.

Wang, L; Ross, J

1990-01-01

26

The effect of an orthogonal dc bias field on hysteresis in isotropic magnetic materials under the action of an ac exciting field was investigated. The experimental results indicated that the orthogonal field rotated the hysteresis loops on the BH plane and reduced the enclosed area. As a result, the effective permeability, hysteresis loss, coercivity and remanence decreased with increasing orthogonal bias field. By including the orthogonal field in the anhysteretic model equation and incorporating a variable reversibility coefficient, the Jiles-Atherton hysteresis model was extended to describe the behavior of magnetic materials under the action of an orthogonal bias field. Using finite element modeling for evaluating the effective internal orthogonal field, the modeled hysteresis curve showed quantitative agreement with experimental results.

Bi, Y.; Jiles, D.C.

1999-09-01

27

Hysteresis and gold in metal-insulator-semiconductor (MIS) capacitors

Measurements on gold diffused MIS capacitors, using different dielectric materials, have shown that in addition to changing the surface charge densities present at the silicon-dielectric interface, the gold also reduces the voltage hysteresis commonly observed in the capacitor C-V curves. Some orientation dependent hysteresis results, taken with these gold results, would indicate that the centres responsible for the hysteresis are

S. D. BROTHERTON

1968-01-01

28

A thermodynamically consistent model for magnetic hysteresis

NASA Astrophysics Data System (ADS)

A phenomenological constitutive model is presented to describe the magnetization curve within the context of thermodynamics. Due to the phenomenological analogy between the magnetic hysteresis and the stress hysteresis, the basic structure of the proposed model comes from rate-dependent plasticity in continuum mechanics, namely viscoplasticity. The total magnetic flux density is assumed to be the sum of reversible and irreversible parts. The model introduces the evolution laws of two internal state variables to incorporate the effect of the ever-changing internal microstructure on the current state. The conception originated from viscoplasticity enables the frequency dependence of the hysteresis curve to be modeled.

Ho, Kwangsoo

2014-05-01

29

The magnetization process: Hysteresis

NASA Technical Reports Server (NTRS)

The magnetization process, hysteresis (the difference in the path of magnetization for an increasing and decreasing magnetic field), hysteresis loops, and hard magnetic materials are discussed. The fabrication of classroom projects for demonstrating hysteresis and the hysteresis of common magnetic materials is described in detail.

Balsamel, Richard

1990-01-01

30

Resistive hysteresis in BiFeO 3 thin films

Capacitor-like Au\\/BiFeO3\\/SrRuO3 thin film with (111) orientation was grown on the SrTiO3 (111) substrate by radio frequency magnetic sputtering. It shows a resistive switching behavior, where a stable hysteresis in current–voltage curve was well developed by applying an optimum voltage at room temperature, and it reached the saturation at a bias voltage of 8V. The Child's law in Vmax?0 direction

Jiagang Wu; John Wang; Dingquan Xiao; Jianguo Zhu

2011-01-01

31

Magnetization Process: Hysteresis.

National Technical Information Service (NTIS)

The magnetization process, hysteresis (the difference in the path of magnetization for an increasing and decreasing magnetic field), hysteresis loops, and hard magnetic materials are discussed. The fabrication of classroom projects for demonstrating hyste...

R. Balsamel

1990-01-01

32

Anomalous Ferroelectric Hysteresis Loops.

National Technical Information Service (NTIS)

Materials that exhibit anomalous ferroelectric hysteresis loops appear throughout the literature. These loops have irregular shapes that diverge from the normal hysteresis loop which is characteristic of most ferroelectrics. The observation of a unique hy...

F. J. Murdoch

1971-01-01

33

A phenomenological mathematical model of hysteresis

This paper starts with the description of a purely mathematical model of the saturation curve and the hysteresis loop based on the fundamental similarities between the Langevin function the specified T(x) function and the sigmoid shape. The T(x) function which is composed of tangent hyperbolic and linear functions with its free parameters can describe the regular anhysteretic magnetisation curve. Developed

J. Takács

2001-01-01

34

Oxygen ion drift-driven dual bipolar hysteresis curves in a single Pt/Ta2O5-x/TiOxNy framework

NASA Astrophysics Data System (ADS)

We describe abnormal dual bipolar resistive switching events in simple Pt/Ta2O5-x/TiOxNy and Pt/Ta2O5-x/TiN matrices in which the typical switching directions (SD) are initially clockwise (CW). The negative difference region in a high resistance state before reaching the typical "CW set" process enables the SD transition to a counterclockwise direction. It thereby emphasizes the occurrence of a highly stable secondary bipolar resistive switching curve. The origin of two different switching modes is described by adapting a bias-dependent oxygen ion accumulation and depletion process at TiOxNy and TiN electrode interfaces and by performing various structural analyses.

Lee, Ah Rahm; Cheol Bae, Yoon; Ho Baek, Gwang; Bock Chung, Je; Sung Kang, Tae; Sun Lee, Jong; Park, Jea-Gun; Sik Im, Hyun; Pyo Hong, Jin

2013-10-01

35

Evapotranspiration (ET) is an important component of the water cycle in terrestrial ecosystems. Understanding the ways in which ET changes with meteorological factors is central to a better understanding of ecological and hydrological processes. In this study, we used eddy covariance measurements of ET from a typical alpine shrubland meadow ecosystem in China to investigate the hysteresis response of ET to environmental variables including air temperature (Ta), vapor pressure deficit (VPD) and net radiation (Rn) at a diel timescale. Meanwhile, the simulated ET by Priestly-Taylor equation was used to interpret the measured ET under well-watered conditions. Pronounced hysteresis was observed in both Ta and VPD response curves of ET. At a similar Ta and VPD, ET was always significantly depressed in the afternoon compared with the morning. But the hysteresis response of ET to Rn was not evident. Similar hysteresis patterns were also observed in the Ta/VPD response curves of simulated ET. The magnitudes of the measured and simulated hysteresis loops showed similar seasonal variation, with relatively smaller values occurring from May to September, which agreed well with the lifetime of plants and the period of rainy season at this site. About 62% and 23% of changes in the strength of measured ET-Ta and ET-VPD loops could be explained by the changes in the strength of simulated loops, respectively. Thus, the time lag between Rn and Ta/VPD is the most important factor generating and modulating the ET-Ta/VPD hysteresis, but plants and water status also contribute to the hysteresis response of ET. Our research confirmed the different hysteresis in the responses of ET to meteorological factors and proved the vital role of Rn in driving the diel course of ET. PMID:24896829

Zheng, Han; Wang, Qiufeng; Zhu, Xianjin; Li, Yingnian; Yu, Guirui

2014-01-01

36

Evapotranspiration (ET) is an important component of the water cycle in terrestrial ecosystems. Understanding the ways in which ET changes with meteorological factors is central to a better understanding of ecological and hydrological processes. In this study, we used eddy covariance measurements of ET from a typical alpine shrubland meadow ecosystem in China to investigate the hysteresis response of ET to environmental variables including air temperature (Ta), vapor pressure deficit (VPD) and net radiation (Rn) at a diel timescale. Meanwhile, the simulated ET by Priestly-Taylor equation was used to interpret the measured ET under well-watered conditions. Pronounced hysteresis was observed in both Ta and VPD response curves of ET. At a similar Ta and VPD, ET was always significantly depressed in the afternoon compared with the morning. But the hysteresis response of ET to Rn was not evident. Similar hysteresis patterns were also observed in the Ta/VPD response curves of simulated ET. The magnitudes of the measured and simulated hysteresis loops showed similar seasonal variation, with relatively smaller values occurring from May to September, which agreed well with the lifetime of plants and the period of rainy season at this site. About 62% and 23% of changes in the strength of measured ET-Ta and ET-VPD loops could be explained by the changes in the strength of simulated loops, respectively. Thus, the time lag between Rn and Ta/VPD is the most important factor generating and modulating the ET-Ta/VPD hysteresis, but plants and water status also contribute to the hysteresis response of ET. Our research confirmed the different hysteresis in the responses of ET to meteorological factors and proved the vital role of Rn in driving the diel course of ET.

Zheng, Han; Wang, Qiufeng; Zhu, Xianjin; Li, Yingnian; Yu, Guirui

2014-01-01

37

Theory of molecular hysteresis switch

NASA Astrophysics Data System (ADS)

Molecular hysteresis switching has been recently observed in a series of experiments that measured the I-V spectrum of bipyridyl-dinitro oligophenylene-ethylene dithiol (BPDN) based molecular devices [1]. The experimental observations clearly show the presence of Coulomb blockade in single organic molecules that is responsible for the voltage-induced switching. We present the theory of the hysteresis switch which explains the non-linear hysteresis I-V characteristics based on the mechanisms of Coulomb blockade and the existence of two different molecular conformations of neutral and charged states of the molecule. [1] A.S. Blum, J.G. Kushmerick, D.P. Long, C.H. Patterson, J.C. Yang, J.C. Henderson, Y.X. Yao, J.M. Tour, R. Shashidhar, and B.R. Ratna, ``Molecularly inherent voltage-controlled conductance switching'' , Nature Materials 4, 167 (2005).

Kozhushner, Mortko; Oleynik, Ivan

2006-03-01

38

Efficient Computational Model of Hysteresis

NASA Technical Reports Server (NTRS)

A recently developed mathematical model of the output (displacement) versus the input (applied voltage) of a piezoelectric transducer accounts for hysteresis. For the sake of computational speed, the model is kept simple by neglecting the dynamic behavior of the transducer. Hence, the model applies to static and quasistatic displacements only. A piezoelectric transducer of the type to which the model applies is used as an actuator in a computer-based control system to effect fine position adjustments. Because the response time of the rest of such a system is usually much greater than that of a piezoelectric transducer, the model remains an acceptably close approximation for the purpose of control computations, even though the dynamics are neglected. The model (see Figure 1) represents an electrically parallel, mechanically series combination of backlash elements, each having a unique deadband width and output gain. The zeroth element in the parallel combination has zero deadband width and, hence, represents a linear component of the input/output relationship. The other elements, which have nonzero deadband widths, are used to model the nonlinear components of the hysteresis loop. The deadband widths and output gains of the elements are computed from experimental displacement-versus-voltage data. The hysteresis curve calculated by use of this model is piecewise linear beyond deadband limits.

Shields, Joel

2005-01-01

39

Mathematical models of hysteresis

A new approach to Preisach's hysteresis model, which emphasizes its phenomenological nature and mathematical generality, is briefly described. Then the theorem which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by Preisach's model is proven. The significance of this theorem is that it establishes the limits of applicability of this model.

I. Mayergoyz

1986-01-01

40

ERIC Educational Resources Information Center

This paper describes a reproducible process where the irreversibility can be readily evaluated and provides a thermodynamic description of the important phenomenon of hysteresis. A metal hydride is used because hysteresis is observed during the formation and decomposition of the hydride phase. (RH)

Flanagan, Ted B., And Others

1987-01-01

41

A viscous-type dynamic hysteresis model (DHM) is developed. The DHM is compatible with static underlying model of any type and nature (Preisach or non-Preisach). The distinguishing features of the DHM are its arbitrary frequency dependence and the ability to control the shape of the dynamic hysteresis loop. The numerical method for the incorporation of the DHM in magnetodynamic computations is

S. E. Zirka; Y. I. Moroz; P. Marketos; A. J. Moses

2004-01-01

42

Dynamical aspects of the adsorption hysteresis phenomenon

Equilibrium and nonequilibrium transport properties of adsorbates in mesoporous Vycor porous glass have been experimentally studied using nuclear magnetic resonance techniques. With the known geometrical characteristics of porous glass and with measured self- diffusivities, transient sorption curves have been quantitatively compared to those predicted within a Fick's law model. This model correctly describes data outside a hysteresis region. In contrast,

Rustem Valiullina; Sergej Naumov; Peter A. Monson

43

Isothermal magnetization curves, like hysteresis loops, initial curves, back field curves, acquisition curves and demagnetizing curves of isothermal remanent magnetization, are commonly used for rock magnetic purposes. In this study we investigate the relations among these curves and other useful magnetization curves (saturation initial curve and induced and remanent hysteretic magnetization curves) in order to compare coercivity and domain state

Karl Fabian; Tilo von Dobeneck

1997-01-01

44

Scaling of hysteresis loop of interacting polymers under a periodic force

NASA Astrophysics Data System (ADS)

Using Langevin dynamics simulations, we study a simple model of interacting-polymer under a periodic force. The extension curves strongly depend on the magnitude of the amplitude (F) and the frequency (?) of the applied force. In low frequency limit, the system retraces the thermodynamic path. At higher frequencies, response time is greater than the external time scale for change of force, which restrict the biomolecule to explore a smaller region of phase space that results in hysteresis of different shapes and sizes. We show the existence of dynamical transition, where area of hysteresis loop approaches to a large value from nearly zero value with decreasing frequency. The area of hysteresis loop is found to scale as F??? for the fixed length. These exponents are found to be the same as of the mean field values for a time dependent hysteretic response to periodic force in case of the isotropic spin.

Mishra, Rakesh Kumar; Mishra, Garima; Giri, Debaprasad; Kumar, Sanjay

2013-06-01

45

Scaling of hysteresis loop of interacting polymers under a periodic force.

Using Langevin dynamics simulations, we study a simple model of interacting-polymer under a periodic force. The extension curves strongly depend on the magnitude of the amplitude (F) and the frequency (?) of the applied force. In low frequency limit, the system retraces the thermodynamic path. At higher frequencies, response time is greater than the external time scale for change of force, which restrict the biomolecule to explore a smaller region of phase space that results in hysteresis of different shapes and sizes. We show the existence of dynamical transition, where area of hysteresis loop approaches to a large value from nearly zero value with decreasing frequency. The area of hysteresis loop is found to scale as F(?)?(?) for the fixed length. These exponents are found to be the same as of the mean field values for a time dependent hysteretic response to periodic force in case of the isotropic spin. PMID:23822272

Mishra, Rakesh Kumar; Mishra, Garima; Giri, Debaprasad; Kumar, Sanjay

2013-06-28

46

Adhesion hysteresis of silane coated microcantilevers

The authors have developed a new experimental approach for measuring hysteresis in the adhesion between micromachined surfaces. By accurately modeling the deformations in cantilever beams that are subject to combined interfacial adhesion and applied electrostatic forces, they determine adhesion energies for advancing and receding contacts. They draw on this new method to examine adhesion hysteresis for silane coated micromachined structures and found significant hysteresis for surfaces that were exposed to high relative humidity (RH) conditions. Atomic force microscopy studies of these surfaces showed spontaneous formation of agglomerates that they interpreted as silages that have irreversibly transformed from uniform surface layers at low RH to isolated vesicles at high RH. They used contact deformation models to show that the compliance of these vesicles could reasonably account for the adhesion hysteresis that develops at high RH as the surfaces are forced into contact by an externally applied load.

DE BOER,MAARTEN P.; KNAPP,JAMES A.; MICHALSKE,TERRY A.; SRINIVASAN,U.; MABOUDIAN,R.

2000-04-17

47

Hysteresis heating based induction bonding of composite materials

NASA Astrophysics Data System (ADS)

The viability of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composites is well established in this work. The unique ability to offer localized heating, geometric flexibility, and self-controlled temperature is the major advantage of this technique. Hysteresis heating is tailored through careful design of the microstructure of nickel particulate polymer films (Ni/PSU). An excellent heating rate can be attained in the frequency range of 1 to 10 MHz for particle volume fraction below percolation of 0.26. The diameter of nickel particle should be kept between 65 nm to 10 mum to ensure multi-domain heating, Curie temperature control, negligible shielding effect, minimum eddy current, and slight particle oxidation. The hysteresis heating behavior of the Ni/PSU films is found to be volumetric in nature and proportional to the cube of applied magnetic field. On the other hand, heat generation is inversely proportional to the size of the multi-domain particles. The frequency effect; however, provide maximum heat generation at the domain wall resonance frequency. Curie temperature control is observed when sufficiently high magnetic fields (˜138 Oe) are applied. The master curves of AC heat generation in Ni/PSU films are established and show a strong particle size effect. Hysteresis fusion bonding of glass/polyphenylene sulfide thermoplastic composites using a magnetic film as the thermoplastic adhesive shows that the bond strength of hysteresis-welded materials is comparable to that of autoclave-welded materials while offering an order of magnitude reduction in cycle time. The relative contribution of the intimate contact and healing mechanisms to the fusion bonding process indicates that hysteresis bonding is controlled by intimate contact. The macroscopic failure modes vary from mostly adhesive composite/film (low bond strength) to a combination of adhesive composite/film, cohesive film, cohesive composite and mostly cohesive composite (high bond strength). Inspection of the microscopic failure at the nickel particle/polymer interface in the film indicates quasi-brittle failure mode. The amount of adhesive failure increases with decreasing particle size and increasing particle volume fraction. The XPS peaks confirm nickel oxide in the form of NiO on the failure surface of particle/polymer debonding of hysteresis susceptor film.

Suwanwatana, Witchuda

48

Hysteresis effects in Bose-Einstein condensates

Here, we consider damped two-component Bose-Einstein condensates with many-body interactions. We show that, when the external trapping potential has a double-well shape and when the nonlinear coupling factors are modulated in time, hysteresis effects may appear under some circumstances. Such hysteresis phenomena are a result of the joint contribution of the appearance of saddle node bifurcations and the damping effect.

Sacchetti, Andrea [Faculty of Sciences, University of Modena e Reggio Emilia, Via Campi 213/B, I-41100 Modena (Italy)

2010-07-15

49

NSDL National Science Digital Library

The STP Hysteresis program is a Monte Carlo simulation of a two-dimensional Ising model demonstrating that the magnetization does not immediately change when the external magnetic field is changed. The default is a lattice of linear dimension L=32 (for a total of N=L^2 spins), a temperature T=1.8 and an external field that changes from H=1 to H=-1 and then returns to its original value. STP Hysteresis is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_Hysteresis.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-13

50

A simple method to determine dynamic hysteresis loops of soft magnetic materials

An approach to plotting hysteresis curves of soft magnetic materials using a personal computer assisted measuring system is presented. The resulting hysteresis curves provide enough detail to allow determination of the parameters required for a simulation with PSPICE (Jiles-Atherton model) or the Hodgdon\\/Carpenter model. The magnetic core loss for different materials and core shapes can be determined at frequencies up

N. Schmidt; H. Guldner

1996-01-01

51

The Unsymmetrical Hysteresis Loop

The paper gives results and analyses of tests to determine losses in hysteresis loops wherein the magnetism is carried through cycles in which limiting values of flux are different in amount or the mean values of flux differ from zero. Such variations of magnetism occur in inductor generators, in teeth of induction machines and in materials magnetized from rectifier circuits,

John D. Ball

1915-01-01

52

Hysteresis phenomena of the intelligent driver model for traffic flow.

We present hysteresis phenomena of the intelligent driver model for traffic flow in a circular one-lane roadway. We show that the microscopic structure of traffic flow is dependent on its initial state by plotting the fraction of congested vehicles over the density, which shows a typical hysteresis loop, and by investigating the trajectories of vehicles on the velocity-over-headway plane. We find that the trajectories of vehicles on the velocity-over-headway plane, which usually show a hysteresis loop, include multiple loops. We also point out the relations between these hysteresis loops and the congested jams or high-density clusters in traffic flow. PMID:17677531

Dahui, Wang; Ziqiang, Wei; Ying, Fan

2007-07-01

53

Inverse Compensation for Ferromagnetic Hysteresis.

National Technical Information Service (NTIS)

This paper addresses the validation of an energy-based inverse compensator for hysteresis in ferromagnetic transducers. At moderate to high drive levels such transducers exhibit significant constitutive non-linearities and hysteresis due to domain mechani...

R. C. Smith R. Zrostlik

1999-01-01

54

Role of reversible susceptibility in ferromagnetic hysteresis

NASA Astrophysics Data System (ADS)

An equation of state based upon saturation magnetization, Ms, coercive field, Hc, and the reversible susceptibility function of magnetization is proposed for ferromagnetic hysteresis. Reversible susceptibility divided by the initial susceptibility is the anisotropy function of magnetization, ?r, ranging from one in the demagnetized state to zero at saturation, and varying with magnetic history. Its dependence on scaled magnetization, m=M/Ms on the interval (-1,1) varies with material, allowing characterization of anisotropy classes. Precise measurements have been made of reversible susceptibility, initial and saturate magnetization curves, and loops for Orthonol™, annealed 3% nickel steel and as-received 1018 steel, representing crystals, isotropic polycrystals and composite ferromagnets, respectively. Magnetization change is the product of the reversible susceptibility, change in the applied field and the cooperative function due to domain interactions. This function is 1+?m for the virgin curve with half this slope from any reversal, where ?=Ms/XiHc is the hysteresis coefficient. Variation of ? for 1018 steel is due to distributed coercivities, and causes sigmoid B(H) curves. In the scaled field representation, where h=H/Hc, the cooperative function is 1/(1-h?r), a hyperbolic field dependence smeared by the anisotropy function. Constant anisotropy causes closed hysteresis loops, while variable anisotropy causes creeping of cycled asymmetric loops. In ferromagnetism, 1/?=1/?r-h, normal scaled reluctivity is reduced from its reversible value by the scaled field.

Schneider, Carl S.

2002-05-01

55

Transport, hysteresis and avalanches in artificial spin ice systems

We examine the hopping dynamics of an artificial spin ice system constructed from colloids on a kagome optical trap array where each trap has two possible states. By applying an external drive from an electric field which is analogous to a biasing applied magnetic field for real spin systems, we can create polarized states that obey the spin-ice rules of two spins in and one spin out at each vertex. We demonstrate that when we sweep the external drive and measure the fraction of the system that has been polarized, we can generate a hysteresis loop analogous to the hysteretic magnetization versus external magnetic field curves for real spin systems. The disorder in our system can be readily controlled by changing the barrier that must be overcome before a colloid can hop from one side of a trap to the other. For systems with no disorder, the effective spins all flip simultaneously as the biasing field is changed, while for strong disorder the hysteresis curves show a series of discontinuous jumps or avalanches similar to Barkhausen noise.

Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, A [BABES-BOLYAI UNIV.

2010-01-01

56

The hysteresis behavior of an Ising nanowire with core/shell morphology: Monte Carlo treatment

NASA Astrophysics Data System (ADS)

We have used Monte Carlo Simulations (MCS) to study the hysteresis behavior of the magnetic nanowire with core/shell morphology described by the spin {1}/{2} Ising particles in the core and the spin {3}/{2} Ising particles in the surface shell. The hysteresis curves are obtained for different temperatures. We find that the hysteresis loop areas decrease when the temperature increases and the hysteresis loops disappear at certain temperatures. Barkhausen jumps are observed for the ferromagnetic nanowire system. An unusual form of triple hysteresis behaviors is observed for the ferrimagnetic nanowire system. The thermal behaviors of the coercivity and the remanent magnetization are also investigated.

Boughazi, B.; Boughrara, M.; Kerouad, M.

2014-08-01

57

Modeling concentration-dependent sorption-desorption hysteresis of atrazine in a loam soil.

Nonequilibrium sorption plays an active role in the transport of organic contaminants in soil. We applied a two-stage, one-rate model (2S1R) and a new, nonlinear variant (2S1RN) of this model to examine the effects of wastewater irrigation on the sorption kinetics of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) in soil. The models were applied to previously published sorption-desorption data sets, which showed pronounced deviations between sorption curves and desorption curves (sorption-desorption hysteresis). Moreover, the slopes of the desorption curves decreased with decreasing concentration. Different treatments had been used, and two experimental time steps (2 and 14 d) were used. Treatments considered were lipid removal, fulvic and humic acid removal, and untreated soil. The 2S1R model was unable to reproduce the observed type of hysteresis, but the 2S1RN model, which assumes that the sorption-desorption process follows a power function relationship, was able to reproduce the observed type of hysteresis. Visually, applying the new model improved the model fits in all test cases. Statistically, as tested by an extra sum of squares analysis, the new model performed significantly better in 50% of all test cases. According to an example simulation, the choice of the sorption model has a considerable impact on the prediction of atrazine transport in soil. PMID:21520761

Anagu, Ihuaku; Ingwersen, Joachim; Drori, Yaron; Chefetz, Benny; Streck, Thilo

2011-01-01

58

This paper presents a novel real-time inverse hysteresis compensation method for piezoelectric actuators exhibiting asymmetric hysteresis effect. The proposed method directly utilizes a modified Prandtl-Ishlinskii hysteresis model to characterize the inverse hysteresis effect of piezoelectric actuators. The hysteresis model is then cascaded in the feedforward path for hysteresis cancellation. It avoids the complex and difficult mathematical procedure for constructing an inversion of the hysteresis model. For the purpose of validation, an experimental platform is established. To identify the model parameters, an adaptive particle swarm optimization algorithm is adopted. Based on the identified model parameters, a real-time feedforward controller is implemented for fast hysteresis compensation. Finally, tests are conducted with various kinds of trajectories. The experimental results show that the tracking errors caused by the hysteresis effect are reduced by about 90%, which clearly demonstrates the effectiveness of the proposed inverse compensation method with the modified Prandtl-Ishlinskii model. PMID:22755661

Gu, Guo-Ying; Yang, Mei-Ju; Zhu, Li-Min

2012-06-01

59

A new dynamic model of hysteresis in harmonic drives

In this paper, we propose a new dynamic model to describe the hysteresis phenomenon in harmonic drives. The experimental observation of the dynamic torque-displacement relationship for a harmonic drive shows a hysteresis characteristic indicating the simultaneous presence of energy storage and energy dissipation mechanisms. To completely characterize these mechanisms and yet have a simple representation for control, we develop a

Rached Dhaouadi; Fathi H. Ghorbel; Prasanna S. Gandhi

2003-01-01

60

A numerical method for analyzing a passive fault current limiter considering hysteresis

Fast transient analysis of a passive fault current limiter (FCL) using permanent magnets can be done by direct numerical solution of a single non-linear differential equation. The non-linear B-H excursion that is caused by hysteresis is incorporated in the computation using a transient hysteresis model. Rational fractions are used to represent the parent hysteresis loop curves. Since the method uses

A. Mukherjee; S. C. Mukhopadhyay; M. Iwahara; S. Yamada; F. P. Dawson

1998-01-01

61

Topological hysteresis in stripe domain structures

Irreversible evolution in stripe domain structures in a bubble material was investigated. Equilibrium parallel stripe structure folds progressively up to the labyrinth one under normal magnetic field cycles. This topological hysteresis, not related to wall-pinning by defects but to nucleation and collapse field problems, shows memory effects of upper fields encountered.

P. Molho; J. Gouzerh; J. C. S. Levy; J. L. Porteseil

1986-01-01

62

Topological hysteresis in stripe domain structures

NASA Astrophysics Data System (ADS)

Irreversible evolution in stripe domain structures in a bubble material was investigated. Equilibrium parallel stripe structure folds progressively up to the labyrinth one under normal magnetic field cycles. This topological hysteresis, not related to wall-pinning by defects but to nucleation and collapse field problems, shows memory effects of upper fields encountered.

Molho, P.; Gouzerh, J.; Levy, J. C. S.; Porteseil, J. L.

1986-02-01

63

NASA Astrophysics Data System (ADS)

The modulation effect of transverse current on the switching with hysteresis characteristics of quasi-1D charge-density wave conductor rubidium blue bronze Rb 0.3MoO 3 single crystals was investigated for the first time. The behavior of the transverse current dependence of second threshold field E ( E-I characteristic curves) was obtained at 24 K under the current source driving. The E gradually decreases with the increase of transverse current IT when transverse current IT exceeds a certain value IC. The E-I curves become smoother and the switching shows a gentle weakening by the increasing of IT. Correspondingly, the I-E properties (voltage source driving) with an obvious switching from a low conducting state to a high conducting state were measured under the modulation of transverse current. Gradually, the E cannot be distinguished with transverse current increase. The areas of the hysteresis characteristics loop become gently smaller when transverse current increases. It is noted that the transverse currents only induce E to decrease when they go up, yet however, hardly affect the back curves of the hysteresis loop. This could explain the effect of the transverse current as not a thermal effect, because the back curves of the hysteresis loop are not identical at different temperatures.

Li, Changzhen; Yin, Di; Li, Dahua; Tang, Zheng; Wang, Junfeng; Xiong, Rui; Shi, Jing; Tian, Decheng

2006-11-01

64

Local Hysteresis in Relaxation Oscillators.

National Technical Information Service (NTIS)

Relaxation oscillations or 'integrate and fire' phenomena are very commonly found in nature. When modulated by an external force a global hysteresis connected with chaos is often encountered. Besides this kind of hysteresis a local form is found in some s...

P. Alstroem B. Christiansen M. T. Levinsen

1988-01-01

65

Moisture Sorption Hysteresis in Wood.

National Technical Information Service (NTIS)

The occurrence of moisture sorption hysteresis in wood, and several proposed theories for explaining it, are discussed. Hysteresis is shown to be beneficial when wood is in use because it reduces changes in moisture content (lower effective slope of the s...

C. Skaar

1979-01-01

66

Hysteresis and bistability in periodically paced cardiac tissue

NASA Astrophysics Data System (ADS)

Hysteresis in periodically paced cardiac tissue is an important issue due to its relevance to cardiac arrhythmias. In the present paper, the mechanism of hysteresis formation and the related properties are interpreted by numerically investigating the phase I Luo-Rudy model. A formula calculating the width of hysteresis is proposed and well confirmed by numerical simulations. We also find that hysteresis in cardiac tissue shows several characteristics due to couplings among cardiac cells which are absent in a single cell. The influences of the physiological parameters are studied in detail. The model dependence of hysteresis is elucidated by considering a number of well-known models of excitable media. Moreover, the influence of bistability on controlling arrhythmias is revealed.

Huang, Xiaodong; Qian, Yu; Zhang, Xiaoming; Hu, Gang

2010-05-01

67

A method for the determination of the parameters of the hysteresis model of magnetic materials

Many methods have been proposed for the determination of the hysteresis loops of magnetic materials, and many mathematical approaches have been proposed to find a good model for the hysteresis phenomenon. However, very few attempts have been made to determine the parameters of the hysteresis model experimentally. This paper shows how, starting from a digital method for the experimental determination

L. D'Alessandro; A. Ferrero

1994-01-01

68

The significance of observed rotational magnetic hysteresis in lunar samples

NASA Technical Reports Server (NTRS)

Rotational magnetic hysteresis curves for lunar soils 10084, 12070, and 14259, and rock 14053 have been published. There is no adequate explanation to date for the observed large hysteresis at high fields. Lunar rock magnetism researchers consider fine particle iron to be the primary source of stable magnetic remanence in lunar samples. Iron has cubic anisotropy with added shape anisotropy for extreme particle shapes. The observed high-field hysteresis must have its source in uniaxial or unidirectional anisotropy. This implies the existence of minerals with uniaxial anisotropy or exchange-coupled spin states. Therefore, the source of this observed high-field hysteresis must be identified and understood before serious paleointensity studies are made. It is probable that the exchange-coupled spin states and/or the source of uniaxial anisotropy responsible for the high-field hysteresis might be influenced by the lunar surface diurnal temperature cycling. The possible sources of high-field hysteresis in lunar samples are presented and considered.

Wasilewski, P.

1974-01-01

69

Mathematical Models of Hysteresis (Dynamic Problems in Hysteresis).

National Technical Information Service (NTIS)

This research has further advanced the current state of the art in the areas of dynamic aspects of hysteresis and nonlinear large scale magnetization dynamics. The results of this research will find important engineering applications in the areas of magne...

I. Mayergoyz

2006-01-01

70

Hysteresis of Magnetite, Hematite and Pyrrhotite Crystals at High and Low Temperatures

NASA Astrophysics Data System (ADS)

Alternating gradient force magnetometers and sensitive vibrating-sample magnetometers operating above, at, and below room temperature have enabled rapid reliable measurements of hysteresis and remanence curves. The hysteresis parameters Ms, Mrs, Hc, plus the remanence coercivity Hcr, are routinely determined, at room temperature at least, and reported in the form of a Day plot as an indication of domain state and inferred grain size. Yet our knowledge of the hysteresis and remanence properties of individual crystals or sized crystal aggregates of magnetite, titanomagnetite, hematite, pyrrhotite and other important magnetic minerals has scarcely advanced beyond what was known at the end of the 1980's. Applications have indeed outstripped fundamental studies. This presentation will focus on new hysteresis measurements for well-sized magnetites of a variety of origins; magnetite inclusions in plagioclase, pyroxene, amphiboles and biotite; hematite; and pyrrhotite. Measurements were made at 20oC intervals from 25oC to the Curie point for all magnetites and hematites and at 10oC intervals for pyrrhotite. For one set of sized magnetites (0.6, 3, 6, 9, 14 and 110 micrometers), hysteresis and back-field remanence curves were also measured below room temperature (every 10 K from 10 K to 70 K, every 5 K from 80 K to 140 K, and every 10 K from 150 K to 300 K). These data give a wealth of information about the individual mineral crystals and trends linking crystals of common origin but different sizes. From Ms(T) we obtain precise Curie points and transition temperatures. Mrs(T)/Ms(T) tracks sometimes subtle changes in domain structure with changing temperature. Hc(T) gives an indication of the mechanism(s) of anisotropy, important for understanding TRM acquisition in crystals above single-domain size. Mrs(T) and Hc(T) often show substantial irreversible changes in the first heating- cooling cycle, particularly but not exclusively for synthetic crystals, stabilizing in subsequent cycles. Finally, Mrs(T)/Ms(T) vs. Hcr(T)/Hc(T) data trace curves on a Day plot showing unmistakable differences in domain structure between monoclinic and cubic magnetite, as well as more subtle changes away from the Verwey transition.

Dunlop, D. J.

2008-12-01

71

NASA Astrophysics Data System (ADS)

The performance of permanent magnets is largely determined by the magnetostatic energy stored in free space (energy product), which depends on both materials properties and magnet geometry. The latter usually differs from laboratory shapes such as spherical samples, and demagnetizing-field corrections must be applied to compare different geometries. However, in nanostructures, especially in thin films, the macroscopic demagnetizing factors D predicted from Maxwell's equations [1] yield unphysical overskewed hysteresis loops [2]. The overskewing is probably a nanoscale effect, but its origin has remained controversial. Our explanation is that nanoscale magnetization processes violate a main condition for the applicability of macroscopy demagnetizing factors, namely the uniform character of the magnetization. In bulk magnets, the magnetization inhomogeneities effectively average to zero, but this is no longer the case if any of the dimension of the magnet becomes small. We explicitly consider granular thin films, where we find a real-structure dependent reduction D, as contrasted to the sometimes assumed infinite slope M(H) at coercivity. --- This research is supported by BREM (RS), ARPA-E, DOE (DJS), and NCMN. --- References: [1] J. A. Osborn, Phys. Rev. 67, 351 (1945); [2] R. Skomski, J.- P. Liu, and D. J. Sellmyer, Phys. Rev. B 60, 7359 (1999).

Skomski, Ralph; George, T. A.; Sellmyer, D. J.

2011-03-01

72

Thermal-expansion hysteresis in graphite\\/glass composites

The thermal-expansion hysteresis phenomena in graphite\\/glass composites was studied. Neat (unfilled) glass and unidirectional composites showed no observable hysteresis, while (0\\/90) cross-ply composites showed significant residual thermal strain (approx. 20 PPM) after thermal cycling (25 ..-->.. 150 ..-->.. 25Â°C). Multiple thermal cycling of the composite and the strengthening of the fiber\\/matrix bond were found to greatly reduce the magnitude of

Janas

1988-01-01

73

Effect of Hysteresis on Measurements of Thin-Film Cell Performance

Transient or hysteresis effects in polycrystalline thin film CdS/CdTe cells are a function of pre-measurement voltage bias and whether Cu is introduced as an intentional dopant during back contact fabrication. When Cu is added, the current-density (J) vs. voltage (V) measurements performed in a reverse-to-forward voltage direction will yield higher open-circuit voltage (Voc), up to 10 mV, and smaller short-circuit current density (Jsc), by up to 2 mA/cm2, relative to scanning voltage in a forward-to-reverse direction. The variation at the maximum power point, Pmax, is however small. The resulting variation in FF can be as large as 3%. When Cu is not added, hysteresis in both Voc and Jsc is negligible however Pmax hysteresis is considerably greater. This behavior corroborates observed changes in depletion width, Wd, derived from capacitance (C) vs voltage (V) scans. Measured values of Wd are always smaller in reverse-to-forward voltage scans, and conversely, larger in the forward-to-reverse voltage direction. Transient ion drift (TID) measurements performed on Cu-containing cells do not show ionic behavior suggesting that capacitance transients are more likely due to electronic capture-emission processes. J-V curve simulation using Pspice shows that increased transient capacitance during light-soak stress at 100 degrees C correlates with increased space-charge recombination. Voltage-dependent collection however was not observed to increase with stress in these cells.

Albin, D.; del Cueto, J.

2011-03-01

74

Sediment Hysteresis Patterns In Singapore Urban Residential Lined Channels

NASA Astrophysics Data System (ADS)

A study involving Jurong West (JW)(68.7 ha) and Ang Mo Kio (AMK)(34.9 ha) residential catchments in Singapore was conducted to analyse temporal total suspended sediment concentrations (TSS) in lined drainage channels during rain events. 53 and 25 storm events were sampled respectively for JW and AMK. 3 types of hysteresis patterns namely, clockwise, eight shaped and random shaped were identified. Data suggested that different impervious cover configurations in both catchments has accounted for different types of hysteresis patterns. Higher impervious cover (84%) in JW produced mainly clockwise, followed by eight shaped and random hysteresis patterns. Lower impervious cover (60%) in AMK produced mainly clockwise hysteresis. Eight shaped and random hysteresis only appeared in AMK when sediment sources like construction activities emerged. Data also showed eight shaped and random hysteresis appeared during higher magnitude of rain events in JW catchment. Different configurations of impervious cover in both catchments also resulted in variations of TSS during rain events. This led to different tightness of hysteresis patterns loops in both catchments. Conclusively, this study has shown that degree of impervious cover, rain magnitude and emergence of new sediment sources in small urban residential has effects on temporal loadings and variations of sediment in small urban residential catchments.

Lee, W.

2006-12-01

75

Sorption hysteresis of benzene in charcoal particles.

Charcoal is found in water, soil, and sediment where it may act as a sorbent of organic pollutants. The sorption of organic compounds to natural solids often shows hysteresis. The purpose of this study was to determine the source of pronounced hysteresis that we found in the sorption of a hydrophobic compound (benzene) in water to a maple-wood charcoal prepared by oxygen-limited pyrolysis at 673 K. Gas adsorption (N2, Ar, CO2), 13C NMR, and FTIR show the charcoal to be a microporous solid composed primarily of elemental (aromatic) C and secondarily of carboxyl and phenolic C. Nonlocal density functional theory (N2, Ar) and Monte Carlo (CO2) calculations reveal a porosity of 0.15 cm3/g, specific surface area of 400 m2/g, and appreciable porosity in ultramicropores < 10 A. Benzene sorption-desorption conditions were chosen to eliminate artificial causes of hysteresis (rate-limiting diffusion, degradation, colloids effect). Charcoal sorbed up to its own weight of benzene at approximately 69% of benzene water solubility. Sorption was highly irreversible over most of the range tested (10(-4)-10(3) microg/mL). A dimensionless irreversibility index (/i) (0 < or = /i < or = 1) based on local slopes of adsorption and desorption branches was evaluated at numerous places along the isotherm. /i decreases as C increases, from 0.9-1 at low concentration to approximately 0 (approximately fully reversible) at the highest concentrations. Using sedimentation and volumetric displacement measurements, benzene is observed to cause pronounced swelling (up to > 2-fold) of the charcoal particles. It is proposed that hysteresis is due to pore deformation by the solute, which results in the pathway of sorption being different than the pathway of desorption and which leads to entrapment of some adsorbate as the polyaromatic scaffold collapses during desorption. It is suggested that intra-charcoal mass transport may be influenced by structural rearrangement of the solid, in addition to molecular diffusion. PMID:12564916

Braida, Washington J; Pignatello, Joseph J; Lu, Yuefeng; Ravikovitch, Peter I; Neimark, Alexander V; Xing, Baoshan

2003-01-15

76

Dynamic Hysteresis in Compacted Magnetic Nanoparticles

NASA Astrophysics Data System (ADS)

The frequency and temperature dependent magnetic response of a bulk soft magnetic nanocomposite made by compacting Fe10Co 90 nanoparticles was measured and modeled. Electron microscopy and x-ray diffraction were used to characterize the size, composition, and structure of the nanoparticles and nanocomposite. Polyol synthesis was used to produce 200 nm particles with average grain size 20 nm and large superparamagnetic fraction. The nanoparticles were consolidated to 90% theoretical density by plasma pressure compaction. The compacted nanoparticles retained the 20 nm average grain size and large superparamagnetic fraction. The nanocomposite resistivity was more than three times that of the bulk alloy. Vibrating sample and SQUID-MPMS magnetometers were used for low frequency magnetic measurements of the nanoparticles and nanocomposite. Compaction reduced the coercivity from 175 Oe to 8 Oe and the effective anisotropy from 124 x 10 3 ergs/cc to 7.9 x 103 ergs/cc. These reductions were caused by increased exchange coupling between surface nanograins, consistent with predictions from the Random Anisotropy model. Varying degrees of exchange coupling existed within the nanocomposite, contributing to a distribution of energy barriers. A permeameter was used for frequency dependent magnetic measurements on a toroid cut from the nanocomposite. Complex permeability, coercivity, and power loss were extracted from dynamic minor hysteresis loops measured over a range of temperatures (77 K - 873 K) and frequencies (0.1 kHz - 100 kHz). The real and imaginary parts of the complex permeability spectrum showed asymmetries consistent with a distribution of energy barriers and high damping. When the complex permeability, power loss, and coercivity were scaled relative to the peak frequency of the imaginary permeability, all fell on universal curves. Various microscopic and macroscopic models for the complex permeability were investigated. The complex permeability was successfully fit by modifying the Cole-Davidson model with a scaling factor that extended the model to higher damping. The additional damping was consistent with the damping from eddy current modeling, showing that the nanocomposite's complex permeability could be explained by combining microscopic effects (the distribution of energy barriers represented by the Cole-Davidson model) with macroscopic effects (damping due to eddy currents).

Chowdary, Krishna M.

77

Hysteresis in Analytical Solutions for Three-phase Flow

NASA Astrophysics Data System (ADS)

Hysteresis in relative permeability is a widely-recognized phenomenon that impacts oil recovery in water and gas (WAG) injection. Several authors (1-3) have constructed analytical solutions for two-phase oil/water or gas/water flow in enhanced oil recovery however, analytical solutions have not previously been constructed for the three-phase flow problem for immiscible water, oil and gas including hysteresis. In this work analytical solutions are constructed for water and gas floods in a previously water-flooded oil reservoir with and without hysteresis. A simplified model is used in the analysis that qualitatively captures the behavior of oil-phase hysteresis for repeated water imbibition and drainage cycles. Many of the displacements considered have a reversal of flow direction within the displacement, requiring a matching condition to be enforced between the imbibition and drainage relative permeability curves at the point of flow reversal. A suitable matching criterion for the hysteretic curves is presented. A single water/gas injection mixture is considered, with varying initial oil and water volumes present in the reservoir. When hysteresis occurs in a displacement the entire saturation path depends on the initial volumes of oil and water present at the onset of WAG flooding. When hysteresis is ignored most of the displacement is identical for a large range of initial oil and water mixtures, with only the velocity of the leading shock changing. For the displacements which only encounter drainage of the water phase, solutions with and without hysteresis are identical. 1) K. M. Furati, ``Effects of Relative Permeability History Dependence on Two-Phase Flow in Porous Media,'' Transport in Porous Media 28: 181-203, 1997. 2) B. Plohr, D. Marchesin, P. Bedrikovetsky and P. Krause, ``Modeling hysteresis in porous media flow via relaxation,'' Computational Geosciences 5: 225-256, 2001. 3) F. M. Van Kats and C. J. Van Duijn, ``A Mathematical Model for Hysteretic Two-Phase Flow in Porous Media,'' Transport in Porous Media 43: 239-263, 2001.

Lambers, J. V.; LaForce, T.

2011-12-01

78

Perceptual hysteresis in the judgment of auditory pitch shift.

Perceptual hysteresis can be defined as the enduring influence of the recent past on current perception. Here, hysteresis was investigated in a basic auditory task: pitch comparisons between successive tones. On each trial, listeners were presented with pairs of tones and asked to report the direction of subjective pitch shift, as either "up" or "down." All tones were complexes known as Shepard tones (Shepard, 1964), which comprise several frequency components at octave multiples of a base frequency. The results showed that perceptual judgments were determined both by stimulus-related factors (the interval ratio between the base frequencies within a pair) and by recent context (the intervals in the two previous trials). When tones were presented in ordered sequences, for which the frequency interval between tones was varied in a progressive manner, strong hysteresis was found. In particular, ambiguous stimuli that led to equal probabilities of "up" and "down" responses within a randomized context were almost fully determined within an ordered context. Moreover, hysteresis did not act on the direction of the reported pitch shift, but rather on the perceptual representation of each tone. Thus, hysteresis could be observed within sequences in which listeners varied between "up" and "down" responses, enabling us to largely rule out confounds related to response bias. The strength of the perceptual hysteresis observed suggests that the ongoing context may have a substantial influence on fundamental aspects of auditory perception, such as how we perceive the changes in pitch between successive sounds. PMID:24874257

Chambers, Claire; Pressnitzer, Daniel

2014-07-01

79

Real and causal hysteresis elements.

Hysteresis is a phenomenon that has been observed across many different materials and situations. Under small-amplitude cyclical motion, classical hysteresis designates a constant loss per cycle over a wide range of frequencies. This is also consistent with an increase in losses or attenuation with frequency that is strictly proportional to the first power of frequency. Unfortunately, the classical (and simple) frequency domain description of hysteresis does not result in a real and causal impulse response, and therefore is not useful for predicting laboratory results. This problem has led to many errors as well as other more fruitful approaches over the years. The frequency domain requirements for hysteresis are re-examined and it is demonstrated that there is a family of solutions that provide real and causal impulse responses over some extended frequency range. The family is conveniently divided into highpass, lowpass, and bandpass causal systems. These are populated by closed form analytical solutions which can be applied to the prediction of motion and waves in hysteretic materials and systems. PMID:24907801

Parker, Kevin J

2014-06-01

80

Efficiency Wage, Commitment and Hysteresis

The efficiency wage model is usually thought of as a plausible model of the natural rate of unemployment which has little to say about its dynamics. This paper establishes that if firms pay efficiency wages and have some degree of commitment over their employment policy, then employment dynamics exhibit hysteresis. The implied behaviour of unemployment, however, is more similar to

Gilles SAINT-PAUL

1995-01-01

81

Control of Hysteresis: Theory and Experimental Results.

National Technical Information Service (NTIS)

Hysteresis in smart materials hinders the wider applicability of such materials in actuators. In this paper, a systematic approach for coping with hysteresis is presented. The method is illustrated through the example of controlling a commercially availab...

X. Tan R. Venkataraman P. S. Krishnaprasad

2001-01-01

82

Hysteresis Development in Superconducting Josephson Junctions.

National Technical Information Service (NTIS)

The resistively and capacitive shunted junction model is used to investigate hysteresis development in superconducting Josephson junctions. Two empirical formulas that relate the hysteresis width and the quasi-particle diffusion length in terms of the jun...

T. F. Refai L. N. Shehata

1988-01-01

83

PSPICE computer modeling of hysteresis effects

Recent versions of PSPICE, a personal computer implementation of the SPICE circuit simulation computer software program, have the capability of simulating the hysteresis loops of magnetic materials. In order to model the hysteresis loop of a particular manufacturer's magnetic core material, the values of five parameters that affect the shape of the hysteresis loop must be established. A method for

S. Prigozy

1993-01-01

84

Hysteresis in stress cycling of amorphous ribbons

NASA Astrophysics Data System (ADS)

The permeability of soft amorphous ribbons shows significant hysteresis through stress cycling. The response of a circuit incorporating an amorphous CoFeNiSiB based ribbon, as a function of longitudinal stress, with a longitudinal excitation field, is measured. The behaviour of the stress impedance is related to domain wall behaviour, at a range of different frequencies, through a simple model of eddy currents in sheets. It is suggested that changes in the pinning mechanism have a profound effect on the measured impedance.

Tomka, G. J.; Milne, J.; Tweed, S.; Thomas, O.

2004-05-01

85

Reduction of Hysteresis in Organic Field-Effect Transistor by Ferroelectric Gate Dielectric

We studied the reduction of hysteresis in pentacene organic field-effect transistors (OFETs) with a ferroelectric poly(vinylidene fluoride and trifluoroethylene) [P(VDF-TrFE)] dipole layer used as a coating of silicon dioxide gate insulator. Although the OFETs without the dipole layer exhibited a hysteresis caused by carrier trapping, such hysteresis was not observed for the OFETs with the P(VDF-TrFE) layers. Experiments showed that

Xiangyu Chen; Wei Ou-Yang; Martin Weis; Dai Taguchi; Takaaki Manaka; Mitsumasa Iwamoto

2010-01-01

86

Hysteresis in pressure-driven DNA denaturation.

In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue. PMID:22496765

Hernández-Lemus, Enrique; Nicasio-Collazo, Luz Adriana; Castañeda-Priego, Ramón

2012-01-01

87

Hysteresis in Pressure-Driven DNA Denaturation

In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.

Hernandez-Lemus, Enrique; Nicasio-Collazo, Luz Adriana; Castaneda-Priego, Ramon

2012-01-01

88

In high speed applications of PMASynRM, hysteresis losses can become the major cause of power dissipation. Therefore, whereas in other kind of machines a rough estimation of hysteresis can be accepted, their importance in PMASynRM justifies a greater effort in calculating them more precisely. This study investigates the hysteresis phenomena of the Permanent Magnet Assisted Synchronous Reluctance Motor (PMASynRM) using coupled FEM and Preisach modelling. Preisach's model, which allows accurate prediction of hysteresis, is adopted in this procedure to provide a nonlinear solution. The computer simulation and experimental result for the i-[lambda] loci show the propriety of the proposed method.

Lee, J.H.; Hyun, D.S. (Hanyang Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering)

1999-05-01

89

Completely inverted hysteresis loops: Inhomogeneity effects or experimental artifacts

NASA Astrophysics Data System (ADS)

Completely inverted hysteresis loops (IHL) are obtained by the superconducting quantum interference device with large cooling fields (>10 kOe) in (La,Sr)MnO3 films with self-assembled LaSrMnO4, an antiferromagnetic interface. Although the behaviours of measured loops show many features characteristic to the IHL, its origin, however, is not due to the exchange coupling between (La,Sr)MnO3/LaSrMnO4, an often accepted view on IHL. Instead, we demonstrate that the negative remanence arises from the hysteresis of superconducting coils, which drops abruptly when lower cooling fields are utilized. Hence the completely inverted hysteresis loops are experimental artifacts rather than previously proposed inhomogeneity effects in complicated materials.

Song, C.; Cui, B.; Yu, H. Y.; Pan, F.

2013-11-01

90

This study investigates the hysteresis phenomena of the permanent magnet assisted synchronous reluctance motor (PMASynRM) using coupled FEM and Preisach modelling. Preisach's model, which allows accurate prediction of hysteresis, is adopted in this procedure to provide a nonlinear solution. The computer simulation and experimental results for the i-? loci show the propriety of the proposed method

Jung Ho Lee; Dong Seek Hyun

1999-01-01

91

Semiempirical model of soil water hysteresis

In order to represent hysteretic soil water retention curves accurately using as few measurements as possible, a new semiempirical model has been developed. It has two postulates related to physical characteristics of the medium, and two parameters, each with a definite physical interpretation, whose values are determined empirically for a given porous medium. Tests of the model show that it provides high-quality optimized fits to measured water content vs. matric pressure wetting curves for a wide variety of media. A practical use of this model is to provide a complete simulated main wetting curve for a medium where only a main drying curve and two points on the wetting curve have been measured. -from Author

Nimmo, J. R.

1992-01-01

92

Hidden hysteresis - population dynamics can obscure gene network dynamics

Background Positive feedback is a common motif in gene regulatory networks. It can be used in synthetic networks as an amplifier to increase the level of gene expression, as well as a nonlinear module to create bistable gene networks that display hysteresis in response to a given stimulus. Using a synthetic positive feedback-based tetracycline sensor in E. coli, we show that the population dynamics of a cell culture has a profound effect on the observed hysteretic response of a population of cells with this synthetic gene circuit. Results The amount of observable hysteresis in a cell culture harboring the gene circuit depended on the initial concentration of cells within the culture. The magnitude of the hysteresis observed was inversely related to the dilution procedure used to inoculate the subcultures; the higher the dilution of the cell culture, lower was the observed hysteresis of that culture at steady state. Although the behavior of the gene circuit in individual cells did not change significantly in the different subcultures, the proportion of cells exhibiting high levels of steady-state gene expression did change. Although the interrelated kinetics of gene expression and cell growth are unpredictable at first sight, we were able to resolve the surprising dilution-dependent hysteresis as a result of two interrelated phenomena - the stochastic switching between the ON and OFF phenotypes that led to the cumulative failure of the gene circuit over time, and the nonlinear, logistic growth of the cell in the batch culture. Conclusions These findings reinforce the fact that population dynamics cannot be ignored in analyzing the dynamics of gene networks. Indeed population dynamics may play a significant role in the manifestation of bistability and hysteresis, and is an important consideration when designing synthetic gene circuits intended for long-term application.

2013-01-01

93

Wave tunneling and hysteresis in nonlinear junctions.

We consider the nonlinear tunneling of a plane wave through a small barrier potential in a medium with self-defocusing, or repulsive, interactions. We show that nonlinearity can either suppress or enhance transmission rates, determined by whether the initial kinetic energy is above or below the barrier height. Associated with this threshold is the appearance of two distinct hysteresis loops, going clockwise or counterclockwise, respectively. Spatial dynamics upon reflection and transmission reveals the formation of dispersive shock waves (dark soliton trains) due to phase jumps at the interfaces and wave steepening during propagation. The results are demonstrated experimentally for optical wave tunneling through a refractive index defect but will hold for any Schrödinger system that contains a nonlinear junction. PMID:20366886

Wan, Wenjie; Muenzel, Stefan; Fleischer, Jason W

2010-02-19

94

Reconfiguration and hysteresis in superconducting Nb film with honeycomb arrays

NASA Astrophysics Data System (ADS)

Superconducting Nb films with honeycomb array of holes are studied using transport measurements. The oscillating magneto-resistance curves are observed up to large flux density. Two types of resistance minima with different field intervals are observed, indicating the reconfiguration of the overall flux lattice from honeycomb to triangular arrangement. Moreover, hysteretic effects are found in a very large field span from H = 2H1 to H = 8.5H1. It is revealed that the hysteresis is related to the presence of interstitial vortices.

He, S. K.; Zhang, W. J.; Wen, Z. C.; Cao, W. H.

2012-12-01

95

Thermal Hysteresis Analysis of MEMS Pressure Sensors

Thermal hysteresis reduction is usually a difficult task to tackle for micromachined pressure sensors especially when shrinking piezoresistive transducer (PRT) sensing elements. Since thermal hysteresis involves the entire thermal cycling history and complicated material properties that vary with temperatures, viscoplastic deformation makes the problem very complicated when dealing with high-precision sensor signals. The approach to simplify and quickly resolve the

J. Albert Chiou; Steven Chen

2005-01-01

96

A theory of DE hysteresis loop

The D-E hysteresis loop of ferroelectrics is theoretically studied on the basis of the Avrami model, extended for the case of applied field dependent sidewise velocity. The exponent for the frequency dependence of the extended volume is obtained. The exponent of the area of hysteresis loop, with respect to the frequncy, is also obtained.

Yoshihiro Ishibashi; Hiroshi Orihara

1995-01-01

97

Corneal hysteresis following descemetorhexis with endokeratoplasty

The corneal biomechanical properties following descemetorhexis with endokeratoplasty (DXEK) and in normal subjects were studied\\u000a in 100 eyes (12 DXEK and 88 age-matched normal subjects). Corneal hysteresis measurements were significantly lower in DXEK\\u000a vs normal subjects. DXEK has a direct effect on corneal hysteresis and corneal biomechanical properties of the human cornea.

Thomas John; David A. Taylor; Mitsugu Shimmyo; Bruce E. Siskowski

2007-01-01

98

High-speed tracking control of piezoelectric actuators using an ellipse-based hysteresis model.

In this paper, an ellipse-based mathematic model is developed to characterize the rate-dependent hysteresis in piezoelectric actuators. Based on the proposed model, an expanded input space is constructed to describe the multivalued hysteresis function H[u](t) by a multiple input single output (MISO) mapping Gamma:R(2)-->R. Subsequently, the inverse MISO mapping Gamma(-1)(H[u](t),H[u](t);u(t)) is proposed for real-time hysteresis compensation. In controller design, a hybrid control strategy combining a model-based feedforward controller and a proportional integral differential (PID) feedback loop is used for high-accuracy and high-speed tracking control of piezoelectric actuators. The real-time feedforward controller is developed to cancel the rate-dependent hysteresis based on the inverse hysteresis model, while the PID controller is used to compensate for the creep, modeling errors, and parameter uncertainties. Finally, experiments with and without hysteresis compensation are conducted and the experimental results are compared. The experimental results show that the hysteresis compensation in the feedforward path can reduce the hysteresis-caused error by up to 88% and the tracking performance of the hybrid controller is greatly improved in high-speed tracking control applications, e.g., the root-mean-square tracking error is reduced to only 0.34% of the displacement range under the input frequency of 100 Hz. PMID:20815625

Gu, Guoying; Zhu, Limin

2010-08-01

99

High-speed tracking control of piezoelectric actuators using an ellipse-based hysteresis model

NASA Astrophysics Data System (ADS)

In this paper, an ellipse-based mathematic model is developed to characterize the rate-dependent hysteresis in piezoelectric actuators. Based on the proposed model, an expanded input space is constructed to describe the multivalued hysteresis function H[u](t) by a multiple input single output (MISO) mapping ?:R2-->R. Subsequently, the inverse MISO mapping ?-1(H[u](t),H[u?](t)u(t)) is proposed for real-time hysteresis compensation. In controller design, a hybrid control strategy combining a model-based feedforward controller and a proportional integral differential (PID) feedback loop is used for high-accuracy and high-speed tracking control of piezoelectric actuators. The real-time feedforward controller is developed to cancel the rate-dependent hysteresis based on the inverse hysteresis model, while the PID controller is used to compensate for the creep, modeling errors, and parameter uncertainties. Finally, experiments with and without hysteresis compensation are conducted and the experimental results are compared. The experimental results show that the hysteresis compensation in the feedforward path can reduce the hysteresis-caused error by up to 88% and the tracking performance of the hybrid controller is greatly improved in high-speed tracking control applications, e.g., the root-mean-square tracking error is reduced to only 0.34% of the displacement range under the input frequency of 100 Hz.

Gu, Guoying; Zhu, Limin

2010-08-01

100

Study of a Radial-Exiting Hysteresis Gyro Motor.

National Technical Information Service (NTIS)

Conventional hysteresis motors have small ratios of the output power to the motor volume as compared with conventional induction motors, because the hysteresis materials have small hysteresis loops. A new rotor structure is proposed in which anisotropic m...

H. Yamada

1973-01-01

101

Boiling hysteresis of impinging circular submerged jets with highly wetting liquids

An experimental study was carried out to characterize the boiling hysteresis of impinging circular submerged jets with highly wetting liquids. The effects of noncondensable gases and surface aging on boiling curves were considered. The present study focused on the effects of jet parameters (jet exit velocity, radial distance from the stagnation point and nozzle diameter) and fluid subcooling on incipient

D. W. Zhou; C. F. Ma; J. Yu

2004-01-01

102

Direct hysteresis measurements on ferroelectret films by means of a modified Sawyer-Tower circuit

NASA Astrophysics Data System (ADS)

Ferro- and piezo-electrets are non-polar polymer foams or film systems with internally charged cavities. Since their invention more than two decades ago, ferroelectrets have become a welcome addition to the range of piezo-, pyro-, and ferro-electric materials available for device applications. A polarization-versus-electric-field hysteresis is an essential feature of a ferroelectric material and may also be used for determining some of its main properties. Here, a modified Sawyer-Tower circuit and a combination of unipolar and bipolar voltage waveforms are employed to record hysteresis curves on cellular-foam polypropylene ferroelectret films and on tubular-channel fluoroethylenepropylene copolymer ferroelectret film systems. Internal dielectric barrier discharges (DBDs) are required for depositing the internal charges in ferroelectrets. The true amount of charge transferred during the internal DBDs is obtained from voltage measurements on a standard capacitor connected in series with the sample, but with a much larger capacitance than the sample. Another standard capacitor with a much smaller capacitance--which is, however, still considerably larger than the sample capacitance--is also connected in series as a high-voltage divider protecting the electrometer against destructive breakdown. It is shown how the DBDs inside the polymer cavities lead to phenomenological hysteresis curves that cannot be distinguished from the hysteresis loops found on other ferroic materials. The physical mechanisms behind the hysteresis behavior are described and discussed.

Qiu, Xunlin; Holländer, Lars; Wirges, Werner; Gerhard, Reimund; Cury Basso, Heitor

2013-06-01

103

A new method of calculating magnetic hysteresis and thermal effects

NASA Astrophysics Data System (ADS)

All the easy theoretical problems in rock magnetism have been solved. Further advances involve models of hysteresis and thermal fluctuations in increasingly complex systems. To model the physics of such systems accurately, rock magnetists will need to solve two seemingly unrelated technical challenges. First, for models of thermal relaxation (with applications to magnetic viscosity, thermoremanent magnetization and so on), they will need to locate energy barriers in multidimensional parameter spaces - a difficult and computationally expensive problem. Second, they will need to improve calculations of magnetization curves near jumps, where the slope of the curve almost always approaches infinity. Micromagnetic models have trouble locating jumps accurately. A new algorithm is presented that tackles both of these problems while greatly reducing the time needed to calculate magnetization curves. The most novel aspect of this algorithm is the way it treats the magnetic field. Other methods solve for the magnetization at a given magnetic field, change the field, and then solve for the magnetization again while the field is kept fixed at the new value. The result is an equilibrium curve in a space of magnetization and field components. The new algorithm treats the field the same way as it treats the magnetization. It uses a tangent to the magnetization curve to estimate the next point on the curve and a corrector algorithm that refines the estimate. There is also an adaptive algorithm to determine an appropriate distance to step along the curve. This algorithm is much more robust near jumps. It can also calculate energy barriers because the top of an energy barrier (a saddle point) is on the same solution curve as the stable magnetization states. Previous methods could not follow the solution curve past the point of instability, but this method can because of the way it handles the field. This makes it possible to calculate energy barriers much faster and more accurately than any previous method. Applications to interacting fine particles will be presented.

Newell, A.

2008-12-01

104

NSDL National Science Digital Library

This page contains a discussion of ogive curves, logistic regression curves, and architecture. Nice photographs of architectural applications are included. The classic Birthday Problems is included as an example of an ogive curve.

2008-01-01

105

Negative and positive hysteresis in double-cavity optical bistability in a three-level atom

NASA Astrophysics Data System (ADS)

We present dual hysteretic behavior of a three-level ladder system exhibiting optical bistability in a double-cavity configuration in the mean-field limit. The two fields coupling the atomic system experience competing cooperative effects along the two transitions. We observe a hump-like feature in the bistable curve arising due to cavity-induced inversion, which transforms into a negative-hysteresis loop. Apart from negative- and positive-hysteresis regions, the system offers a variety of controllable nonlinear dynamical features, ranging from switching, periodic self-pulsing to chaos.

Babu, H. Aswath; Wanare, Harshawardhan

2011-03-01

106

Free Energy Model for Hysteresis Ferroelectric Materials.

National Technical Information Service (NTIS)

This paper provides a theory for quantifying the hysteresis and constitutive nonlinearities inherent to piezoceramic compounds through a combination of free energy analysis and stochastic homogenization techniques. In the first step of the model developme...

R. C. Smith Z. Ounaies S. Seelecke J. Smith

2003-01-01

107

Hydrodynamic Model of Dynamic Contact Angle Hysteresis.

National Technical Information Service (NTIS)

A qualitative hydrodynamic description of dynamic contact angle hysteresis is developed in terms of the interaction of capillary, viscous, and disjoining forces by considerating the slow motion of a fluid-fluid interface being driven through a capillary t...

R. J. Prutow S. Ostrach

1971-01-01

108

Thermal Hysteresis of Interface Biased Ferromagnetic Dots.

National Technical Information Service (NTIS)

We present a theoretical investigation of the thermal hysteresis of iron dots exchange-coupled to an antiferromagnetic substrate. We consider a temperature interval bounded by the Neel temperature of the substrate, and we calculate the heating and cooling...

A. L. Dantas, A. S. Carrico, A. S. Silva, G. O. Reboucas, R. E. Camley

2007-01-01

109

Inversion of hysteresis and creep operators

NASA Astrophysics Data System (ADS)

The explicit inversion formula for rate dependent Prandtl-Ishlinskii operators is extended to cases without the threshold dilation condition. This solves a problem in hysteresis and creep modeling of magnetostrictive behavior.

Krej?í, Pavel; Al Janaideh, Mohammad; Deasy, Fergal

2012-05-01

110

Homogenized Energy Framework for Ferromagnetic Hysteresis.

National Technical Information Service (NTIS)

In this paper, we develop a macroscopic framework quantifying the hysteresis and constitutive nonlinearities inherent to ferromagnetic materials. In the first step of the development, we construct Helmholtz and Gibbs energy relations at the mesoscopic or ...

R. C. Smith M. J. Dapino T. R. Braun A. P. Mortensen

2005-01-01

111

Among the phenomenological hysteresis models, the Preisach model, Krasnosel’skii–Pokrovskii model, and Prandtl–Ishlinskii model have found extensive applications for modeling hysteresis in shape memory alloys and other smart actuators. Since the mathematical complexity of the identification and inversion problem depends directly on the type of phenomenological hysteresis modeling method, choosing a proper phenomenological model among the mentioned models for modeling the

Mohammad R Zakerzadeh; Hassan Sayyaadi

2012-01-01

112

Magnetic resonance imaging (MRI) study of jet height hysteresis in packed beds

NASA Astrophysics Data System (ADS)

The jet-spout transition in fluidized beds can show hysteretic behavior. In this study the jet-spout transition was studied as a function of orifice velocity for particles of different size and shape using Magnetic Resonance Imaging (MRI). The measurements showed that the particle shape primarily affect to the width of the hysteresis loop whereas particle size governs the position of the hysteresis loop with regards to the orifice velocity.

Köhl, Maximilian H.; Lu, Guang; Third, James R.; Prüssmann, Klaas P.; Müller, Christoph R.

2013-06-01

113

PERFORMANCE OF HYSTERESIS PERMANENT MAGNET MOTORS

There is an increasing interest in using permanent magnet (PM) hysteresis motors because of their superior performances over the conventional hysteresis motors. Recent NdBFe magnets have the advantages of higher magnetic energy product and remanence. It can develop significant accelerating torque during run-up and synchronization with limited temperature tolerance. The application of the NdBFe magnets in electrical machines Is attracting

A. M. OSHEIBA; J. QIAN; M. A. RAHMAN

1989-01-01

114

Equivalent Circuit Modeling of Hysteresis Motors

We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates, amenable to circuit or digital simulation. 'Hunting' is an oscillatory phenomenon often observed in hysteresis motors. While several works have attempted to model the phenomenon with some partial success, we present a new complete model that predicts hunting from first principles.

Nitao, J J; Scharlemann, E T; Kirkendall, B A

2009-08-31

115

Spatial versus time hysteresis in damping mechanisms

NASA Technical Reports Server (NTRS)

A description is given of continuing investigations on the task of estimating internal damping mechanisms in flexible structures. Specifically, two models for internal damping in Euler-Bernoulli beams are considered: spatial hysteresis and time hysteresis. A theoretically sound computational algorithm for estimation is described, and experimental results are discussed. It is concluded that both models perform well in the sense that they accurately predict response for the experiments conducted.

Banks, H. T.; Fabiano, R. H.; Wang, Y.; Inman, D. J.; Cudney, H., Jr.

1988-01-01

116

NASA Astrophysics Data System (ADS)

Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.

Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

2014-04-01

117

Preisach modeling of piezoceramic and shape memory alloy hysteresis

Smart materials such as piezoceramics, magnetostrictive materials, and shape memory alloys exhibit significant hysteresis, especially when driven with large input signals. Hysteresis can lead to unwanted harmonics, inaccuracy in open loop control, and instability in closed loop control. The Preisach independent domain hysteresis model has been shown to capture the major features of hysteresis arising in ferromagnetic materials. Noting the

Declan C. Hughes; John T. Wen

1996-01-01

118

Preisach modeling of piezoceramic and shape memory alloy hysteresis

Smart materials such as piezoceramics, magnetostrictive materials, and shape memory alloys exhibit hysteresis, and the larger the input signal the larger the effect. Hysteresis can lead to unwanted harmonics, inaccuracy in open loop control, and instability in closed loop control. The Preisach independent domain hysteresis model has been shown to capture the major features of hysteresis arising in ferromagnetic materials.

Declan Hughes; John T. Wen

1997-01-01

119

Hysteresis effects of changing the parameters of noncooperative games

NASA Astrophysics Data System (ADS)

We adapt the method used by Jaynes to derive the equilibria of statistical physics to instead derive equilibria of bounded rational game theory. We analyze the dependence of these equilibria on the parameters of the underlying game, focusing on hysteresis effects. In particular, we show that by gradually imposing individual-specific tax rates on the players of the game, and then gradually removing those taxes, the players move from a poor equilibrium to one that is better for all of them.

Wolpert, David H.; Harré, Michael; Olbrich, Eckehard; Bertschinger, Nils; Jost, Jürgen

2012-03-01

120

Multistability and hysteresis in the climate-cryosphere system under orbital forcing

NASA Astrophysics Data System (ADS)

Using the Earth system model of intermediate complexity CLIMBER-2 we studied the stability diagram of the climate-cryosphere system in the phase space of Milankovitch forcing (maximum summer insolation at 65°N, abbreviated as MF). We have shown that the equilibrium response of the climate-cyrosphere system to MF reveals pronounced hysteresis behavior within the range of Earth's orbital parameters. Depending on MF, the climate-cryosphere system has either one (glacial or interglacial) or two different equilibrium states. The MF thresholds of the transitions between the two states depend on parameterizations of ice-sheet dynamics, but are rather insensitive to the choice of the orbital parameters used to obtain the same value of MF. A change of atmospheric CO2 concentration from its interglacial to the glacial value, shifts the hysteresis curve by about 15 W/m2. These results provide an important support to the conceptual models of glacial cycles based on multistability and hysteresis behavior.

Calov, Reinhard; Ganopolski, Andrey

2005-11-01

121

Hybrid models of hysteresis for mixed hysteretic loops in heterogeneous magnetic materials

NASA Astrophysics Data System (ADS)

The mixed hysteresis behavior of counter-clockwise and clockwise loops has recently attracted the attention of the magnetics community, due to several experimental findings in inhomogeneous and hetero-structure magnetic systems. Various hybrid models are proposed here to address this behavior based on the superposition of standard hysteresis models and their newly developed clockwise variants. A special attention is also devoted to Bouc-Wen model, a typical clockwise often used by applied mechanics community, and to its relevance for mixed hysteresis. These clockwise and hybrid models have been implemented in an open-access academic software and their performance is illustrated by examples of hysteretic loops, first order reversal curves and diagrams simulated in this framework.

Dimian, M.; Andrei, P.; Grayson, M.

2014-05-01

122

Hysteresis modeling of synchronous reluctance motor considering PWM input voltage

NASA Astrophysics Data System (ADS)

This paper deals with the hysteresis characteristics analysis in PWM fed synchronous reluctance motor (SynRM) using a coupled finite element method (FEM) and Preisach's modeling, which is presented to analyze the characteristics under the effect of saturation and hysteresis loss. With regard to the PWM characteristics, a vector control inverter is combined with an analysis tool. Also, a moving mesh technique is used with regard to rotation due to velocity. The focus of this paper is the applied method of Preisach modeling for rotating machines and the characteristics analysis of a SynRM using the proposed method of analysis. For the propriety of proposed method of analysis, TMS320C31 DSP-installed experimental devices are used. And then, computer simulation and experimental result for the i- ? loci, speed, current response, show the propriety of the proposed method. The characteristic analysis is performed in relation to the maximum efficiency condition for a SynRM in simulation and experiment.

Lee, J. H.; Kim, J. C.; Hyun, D. S.

2000-01-01

123

Contact angle hysteresis on textured surfaces with nanowire clusters.

Nanowire arrays with various agglomeration patterns were synthesized by adjusting the solvent evaporation rates. Nanowires with 200 nm diameter and 2-25 microm in length were fabricated from an anodic aluminum oxide (AAO) porous template. Various drying treatments were applied to develop nanostructured surfaces with topological differences. Due to surface tension forces, copper nanowires after thermal and evaporative drying treatments agglomerated into clusters, while supercritical drying technique provided excellent bundled-free and vertically-standing nanowire arrays. Although all dried surfaces exhibited hydrophobic nature, the contact angle hysteresis, or the difference between advancing and receding angles, was found to be larger on those surfaces with bundled nanowire clusters. To explain the difference, the wetted solid fraction on each surface was calculated using the Cassie-Baxter model to show that the hysteresis was contributed by liquid/solid contact area on the textured surfaces. PMID:23763151

Liao, Ying-Chih; Chiang, Cheng-Kun; Lu, Yen-Wen

2013-04-01

124

Titration and hysteresis in epigenetic chromatin silencing.

Epigenetic mechanisms of silencing via heritable chromatin modifications play a major role in gene regulation and cell fate specification. We consider a model of epigenetic chromatin silencing in budding yeast and study the bifurcation diagram and characterize the bistable and the monostable regimes. The main focus of this paper is to examine how the perturbations altering the activity of histone modifying enzymes affect the epigenetic states. We analyze the implications of having the total number of silencing proteins, given by the sum of proteins bound to the nucleosomes and the ones available in the ambient, to be constant. This constraint couples different regions of chromatin through the shared reservoir of ambient silencing proteins. We show that the response of the system to perturbations depends dramatically on the titration effect caused by the above constraint. In particular, for a certain range of overall abundance of silencing proteins, the hysteresis loop changes qualitatively with certain jump replaced by continuous merger of different states. In addition, we find a nonmonotonic dependence of gene expression on the rate of histone deacetylation activity of Sir2. We discuss how these qualitative predictions of our model could be compared with experimental studies of the yeast system under anti-silencing drugs. PMID:23588040

Dayarian, Adel; Sengupta, Anirvan M

2013-06-01

125

Hysteresis in the Central African Rainforest

NASA Astrophysics Data System (ADS)

Past climate change caused severe disturbances of the Central African rainforest belt, with forest fragmentation and re-expansion due to drier and wetter climate conditions. Besides climate, human induced forest degradation affected biodiversity, structure and carbon storage of Congo basin rainforests. Information on climatically stable, mature rainforest, unaffected by human induced disturbances, provides means of assessing the impact of forest degradation and may serve as benchmarks of carbon carrying capacity over regions with similar site and climate conditions. BioGeoChemical (BGC) ecosystem models explicitly consider the impacts of site and climate conditions and may assess benchmark levels over regions devoid of undisturbed conditions. We will present a BGC-model validation for the Western Congolian Lowland Rainforest (WCLRF) using field data from a recently confirmed forest refuge, show model - data comparisons for disturbed und undisturbed forests under different site and climate conditions as well as for sites with repeated assessment of biodiversity and standing biomass during recovery from intensive exploitation. We will present climatic thresholds for WCLRF stability, analyse the relationship between resilience, standing C-stocks and change in climate and finally provide evidence of hysteresis.

Pietsch, Stephan Alexander; Elias Bednar, Johannes; Gautam, Sishir; Petritsch, Richard; Schier, Franziska; Stanzl, Patrick

2014-05-01

126

Material Data Representation of Hysteresis Loops for Hastelloy X Using Artificial Neural Networks

NASA Technical Reports Server (NTRS)

The artificial neural network (ANN) model proposed by Rumelhart, Hinton, and Williams is applied to develop a functional approximation of material data in the form of hysteresis loops from a nickel-base superalloy, Hastelloy X. Several different ANN configurations are used to model hysteresis loops at different cycles for this alloy. The ANN models were successful in reproducing the hysteresis loops used for its training. However, because of sharp bends at the two ends of hysteresis loops, a drift occurs at the corners of the loops where loading changes to unloading and vice versa (the sharp bends occurred when the stress-strain curves were reproduced by adding stress increments to the preceding values of the stresses). Therefore, it is possible only to reproduce half of the loading path. The generalization capability of the network was tested by using additional data for two other hysteresis loops at different cycles. The results were in good agreement. Also, the use of ANN led to a data compression ratio of approximately 22:1.

Alam, Javed; Berke, Laszlo; Murthy, Pappu L. N.

1993-01-01

127

Mechanisms of magnetic and temperature hysteresis in ErFeO3 and TmFeO3 single crystals

NASA Astrophysics Data System (ADS)

Magnetic hysteresis is studied in the orthoferrites ErFeO3 and TmFeO3 using the single crystal samples of millimeter dimensions. It is shown that in both materials one observes a temperature transition manifesting itself through the temperature hysteresis of the magnetic moment and a peculiar temperature evolution of the field hysteresis loop shapes near this transition. Experiments rule out the hypothesis that the ordering of the orthoferrite's rare-earth magnetic moments plays an important role in these phenomena. The hysteresis curves can be explained by a few-domain magnetic state of the samples that results from the weak ferromagnetism of the orthoferrites. The phenomenon is generic for weak ferromagnets with temperature dependent magnetization. A large characteristic magnetic length makes the behavior of the relatively big samples analogous to that observed in the nanosize samples of strong ferromagnets.

Tsymbal, L. T.; Bazaliy, Ya. B.; Kakazei, G. N.; Vasiliev, S. V.

2010-10-01

128

Hysteresis and Wavenumber Vacillation in Unstable Baroclinic Flows

NASA Technical Reports Server (NTRS)

Hysteresis and wavenumber vacillation are studied numerically in a weakly stratified quasigeostrophic model. In general, the amplitude of the most unstable wave increases, as the flow becomes more unstable. When the wave becomes saturated, the next longer wave will grow at the expanse of the most unstable wave and becomes the dominant wave. However, once the longwave state is established, it may remain in that regime even as the instability is decreased beyond the threshold where it first developed, thus constituting a hysteresis loop. In a highly unstable case, the flow may not show a preference for any single wave. Instead, the dominant wave aperiodically varies among several long waves. This phenomenon is known as wavenumber vacillation. Hysteresis is further examined in terms of eddy heat flux. It is shown that total eddy heat flux increases as the flow becomes more unstable, but displays a sharp drop when transition to a longer wave occurs. However, in a longwave state, the heat flux always decreases with decreasing instability even pass the threshold when wave transition first occurs.

Chou, Shih-Hung; Goodman, H. Michael (Technical Monitor)

2001-01-01

129

Effect of the Bering Strait on the AMOC hysteresis and glacial climate stability (Invited)

NASA Astrophysics Data System (ADS)

Abrupt climate transitions, such as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, especially from 80 - 11 thousand years before present, but were nearly absent during Holocene and the early stages of last glacial period. Here we show, with a fully coupled climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the Atlantic meridional overturning circulation (AMOC) to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open. Qualitatively the same result is arrived in new simulations by employing the glacial background conditions using the same climate model. Theoretical and simulated AMOC hysteresis curves (a, b) and the associated changes of Greenland surface temperature and meridional heat transport at 65°N in the Atlantic (c, d). In panel a), 'S' is the bifurcation point beyond which AMOC collapses and the '+/-F' values indicate the freshwater forcing strength. In panels b), c), and d), the black/red (blue/green) lines are for the closed (open) BS simulation. The black/blue (red/green) lines represent the phase of freshwater forcing increase (decrease) in these simulations. Note that a change of the freshwater forcing by 0.1 Sv (Sv?106m3s-1) in this figure takes place over 500 model years.

Hu, A.; Meehl, G. A.; Han, W.; Timmermann, A.; Otto-Bliesner, B. L.; Liu, Z.; Abe-Ouchi, A.

2013-12-01

130

Analysis of a hysteresis motor with overexcitation

The performance of a hysteresis motor can be improved greatly if it is overexcited for a short period when running at synchronous speed. The change in the magnetic state of the rotor hysteresis material, when the stator voltage is raised and then reduced to the original value, is described in detail. Based on this, a method for the calculation of the motor performance after overexcitation is proposed, and the effect of overexcitation on the motor performance is clarified by using this method. Good agreement is found between the calculated and the measured results.

Kataoka, T.; Ishikawa, T.; Takahasi, T.

1982-11-01

131

Contact Angle Hysteresis of Photo-Responsive Materials

NASA Astrophysics Data System (ADS)

An atomic force microscope (AFM) is used to measure the meniscus force on individual microspheres coated with photo-responsive materials such as anatase and rutile TiO2, azobenzene, and other doped oxides as they contact and are retracted from an air/water interface. By exposing the coated microspheres to UV light, the contact angle change. The change can be detected by measuring the increase in the meniscus force. Exposure to visible, infrared, or far infrared light -- as the specific material requires - reverses the contact angle change. The measured force-distance curves are fitted to macroscopic wetting theory. From these measurements, the contact angle, the contact angle hysteresis, and the position of the contact line pinning were simultaneously determined. This allowed for a quantification of the contact angle changes from photo-switching.

Rosenthal, Samuel; McGuiggan, Patricia

2013-03-01

132

Adsorption Hysteresis and its Effect on CO2 Sequestration and Enhanced Coalbed Methane Recovery

NASA Astrophysics Data System (ADS)

CO2 sequestration in coal reservoirs is a promising technology for reducing atmospheric CO2 concentrations. Of the candidates for geological sequestration, the physics of transport and sequestration in coal is the least well understood. Adsorption hysteresis has been observed for pure gas adsorption on some coals. It is manifest as desorption curves where the loading of gas on coal surfaces is greater than sorption at the same pressure. Current simulation technology does not have the functionality to incorporate this phenomenon that has a potentially great effect on sequestration in coalbeds. Understanding the interplay between adsorption and desorption of gas species, phase behaviour and convection is paramount to designing safe and effective sequestration projects. Our work integrates experiments and theory development. Isotherms of CH4, N2 and CO2 were measured on a sample of coal from the Powder River Basin, WY, for adsorption and desorption paths. Hysteresis was observed for all gases. Likewise, the displacment of methane by various mixtures of N2 and CO2 was also measured. Simultaneously, a model was developed to solve for the dispersion-free limit of convective transport in multiphase systems with adsorption, including the effects of volume change as components transfer from vapour to liquid and solid phases. Analytical solutions were obtained using the method of characteristics. These solutions were compared against corresponding solutions without adsorption hysteresis. For pure gas injection, in which the amount of adsorbed injected gas increases monotonically and the amount of adsorbed initial gas decreases monotonically, hysteresis effects were not observed. For injection gas mixtures of N2-CO2 displacing CH4, CO2 and N2 separated chromatographically and hysteresis effected breakthrough and bank arrival times as well as shifted overall component concentrations as the displacement progressed. When injection gas mixtures were rich in N2, the structures remained similar, but arrival times of component banks were delayed compared to solutions that did not account for adsoprtion hysteresis. For injection gas mixtures rich in CO2, completely different composition route resulted when hysteresis effects were included. From this analysis, adsoprtion hysteresis significantly affects displacement behaviour, impacting process efficiency and recovery time. Neglecting this effect can potentially lead to poor business decisions. For coals that exhibit this behaviour, hysteresis should be included in order to accurately predict displacement behaviour.

Seto, C. J.; Tang, G. T.; Jessen, K.; Kovscek, A. R.; Orr, F. M.

2006-12-01

133

Mechanical Models of Friction That Exhibit Hysteresis, Stick-Slip, and the Stribeck Effect

NASA Astrophysics Data System (ADS)

In this dissertation, we model hysteretic and friction phenomena without introducing friction or hysteresis per se. We use a combination of masses, springs, and dashpots and the frictional phenomena emerge as the result of their interaction. By using physical elements, we can understand the physical mechanisms that lead to hysteretic energy dissipation and phenomena, such as stick-slip behavior and the Stribeck effect. Furthermore, we study the origins of butterfly hysteresis, which arises in optics and ferromagnetism. We define the multiplay model for hysteresis with nonlocal memory, which consists of

Drincic, Bojana

134

A modified Prandtl-Ishlinskii model for modeling asymmetric hysteresis of piezoelectric actuators.

Piezoelectric actuators can offer high resolution of displacement and this makes them suitable for precise driving tasks. However, most piezoelectric actuators are made of piezoceramics which have a major drawback related to their natural hysteresis nonlinearity. To compensate the hysteresis nonlinearity of piezoelectric actuators, many hysteresis models have been proposed such as the Preisach model, the classical Prandtl-Ishlinskii model, and so on. This paper provides a new approach to model the asymmetric hysteresis nonlinearity of piezoelectric actuators. Unlike the classical Prandtl-Ishlinskii model, the proposed model is based on a combination of two asymmetric operators which can independently simulate the ascending branch and descending branch of hysteresis. Moreover, the proposed model can be calculated using the recursive least-squares method and this makes the model easy and convenient to be calculated. The validity of the proposed model is demonstrated by comparing its simulation results with experimental measurements. The results show that the proposed model is capable of modeling asymmetric hysteresis of piezoelectric actuators with very high accuracy. PMID:20442032

Jiang, Hao; Ji, Hongli; Qiu, Jinhao; Chen, Yuansheng

2010-05-01

135

A power and wavelength detuning-dependent hysteresis loop in a single mode Fabry—Pérot laser diode

NASA Astrophysics Data System (ADS)

In this paper, we observe experimentally the optical bistability induced by the side-mode injection power and wavelength detuning in a single mode Fabry—Pérot laser diode (SMFP-LD). Results show that the bistability characteristics of the dominant and injected modes are strongly dependent on the injected input optical power and wavelength detuning in an SMFP-LD. We observe three types of hysteresis loops: counterclockwise, clockwise, and butterfly hysteresis with various loop widths. In the case of a bistability loop caused by injection power, the transition from counterclockwise to clockwise in the hysteresis direction with the wavelength detuning from 0.028 nm to 0.112 nm is observed in a way of butterfly hysteresis for the dominant mode by increasing the wavelength detuning. The width of hysteresis loop, induced by wavelength detuning is also changed while the injection power is enhanced from -7 dBm to -5 dBm.

Wu, Jian-Wei; Bikash, Nakarmi

2013-08-01

136

Hysteresis loops and the inelastic deformation of 0\\/90 ceramic matrix composites

Hysteresis measurements obtained on 0\\/90 SiC\\/CAS and SiC\\/SiC have been used to analyze the interface responses. Four parameters have been derived from these measurements. These relate to the compliance change caused by matrix cracking, the frictional resistance of the interface, the interface debond resistance, and the residual stress. These parameters have been used to predict the stress\\/strain curves. Preliminary estimates

Jean-Marc Domergue; Fernando E. Heredia; Anthony G. Evans

1996-01-01

137

Hysteresis and baseline shift in permanent magnet stabilized MR\\/SAL heads

Hysteresis and baseline shift in shielded permanent magnet stabilized MR\\/SAL playback heads are studied via a 3D micromagnetic simulation. The hysteretic behavior is examined by calculation of playback voltages and uniform field transfer curves. The overlap region between the MR\\/SAL layers and the permanent magnet is seen to have a strong effect on the stability of the device. The amount

Eric Champion; H. Neal Bertram

1996-01-01

138

Re-Examination of Mechanical Hysteresis.

National Technical Information Service (NTIS)

Mechanical-hysteresis loops have been obtained for cycles of torsion applied to copper, brass, low-carbon steel, titanium. It is shown that the slope of the unloading line is determined by a plastic recovery p together with elastic recovery e, that p/e is...

W. A. Wood

1967-01-01

139

Rotational Hysteresis of Exchange-Spring Magnets.

National Technical Information Service (NTIS)

We highlight our experimental studies and micromagnetic simulations of the rotational hysteresis in exchange-spring magnets. Magneto-optical imaging and torque magnetometry measurements for SmCo/Fe exchange-spring films with uniaxial in-plane anisotropy s...

J. S. Jiang R. D. Shull S. D. Bader H. Kaper A. J. Shapiro

2002-01-01

140

Design of hysteresis circuits using differential amplifiers

NASA Technical Reports Server (NTRS)

Design equations for hysteresis circuit are based on the following assumptions: amplifier input impedance is larger than source impedance; amplifier output impedance is less than load impedance; and amplifier switches state when differential input voltage is approximately zero. Circuits are designed to any given specifications.

Cooke, W. A.

1971-01-01

141

Circuit increases capability of hysteresis synchronous motor

NASA Technical Reports Server (NTRS)

Frequency and phase detector circuit enables a hysteresis synchronous motor to drive a load of given torque value at a precise speed determined by a stable reference. This technique permits driving larger torque loads with smaller motors and lower power drain.

Markowitz, I. N.

1967-01-01

142

Flexible pivot mount eliminates friction and hysteresis

NASA Technical Reports Server (NTRS)

Flexible steel pivot mount, suspended by flat vertical beryllium copper springs, is capable of rotation, free of hysteresis and starting friction. Mount requires no lubrication, is made in varying sizes, and is driven with either dc torque motor or mechanical linkage.

Highman, C. O.

1970-01-01

143

Equivalent Circuit Modeling of Hysteresis Motors.

National Technical Information Service (NTIS)

We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates,...

B. A. Kirkendall E. T. Scharlemann J. J. Nitao

2009-01-01

144

Managing Hysteresis: Three Cornerstones to Fiscal Stability

ERIC Educational Resources Information Center

The effects of the Great Recession of 2007-2009 continue to challenge school business officials (SBOs) and other education leaders as they strive to prepare students for the global workforce. Economists have borrowed a word from chemistry to describe this state of affairs: hysteresis--the lingering effects of the past on the present. Today's SBOs…

Weeks, Richard

2012-01-01

145

Role of hysteresis in stomatal aperture dynamics

NASA Astrophysics Data System (ADS)

Stomata are pores responsible for gas exchange in leaves. Several experiments indicate that stomata synchronize into clusters or patches. The patches’ coordination may produce oscillations in stomatal conductance. Previous studies claim to reproduce some experimental results. However, none was able to explain the variety of behavior observed in the stomatal dynamics. Recently, Ferraz and Prado suggested a realistic geometry of vein distribution. Although it reproduces the patches, no oscillation was observed and the patches remain static. Without exploring significant details, the authors stated that hysteresis in stomatal aperture could explain several experimental features. In this paper, the hysteresis hypothesis is further explored through the concept of hysteretic operators. We have shown that the hysteresis assumption is sufficient to obtain dynamical patches and oscillations in stomatal conductance. The robustness of this hypothesis is tested by using different hysteresis operators. The model analysis reveals a dependence between the period of oscillation in stomatal conductance and the water deficit between the leaf and the environment. This underlying feature of the model might inspire further experiments to test this hypothesis.

Ramos, Antônio M. T.; Prado, Carmen P. C.

2013-01-01

146

Geometric Hysteresis of Alveolated Ductal Architecture

Low Reynolds number airflow in the pulmonary acinus and aerosol particle kinetics therein are significantly conditioned by the nature of the tidal motion of alveolar duct geometry. At least two components of the ductal structure are known to exhibit stress-strain hysteresis: smooth muscle within the alveolar entrance rings, and surfactant at the air-tissue interface. We hypothesize that the geometric hysteresis of alveolar duct is largely determined by the interaction of the amount of smooth muscle & connective tissue in ductal rings, septal tissue properties, and surface tension-surface area characteristics of surfactant. To test this hypothesis, we have extended the well-known structural model of the alveolar duct by Wilson and Bachofen (J. Appl. Physiol. 52(4): 1064–1070, 1982) by adding realistic elastic and hysteretic properties of 1) the alveolar entrance ring, 2) septal tissue, and 3) surfactant. With realistic values for tissue and surface properties, we conclude that: 1) there is a significant, and underappreciated, amount of geometric hysteresis in alveolar ductal architecture; and 2) the contribution of smooth muscle and surfactant to geometric hysteresis are of opposite senses, tending toward cancellation. Quantitatively, the geometric hysteresis found experimentally by Miki et al. (J. Appl. Physiol. 75(4): 1630–1636, 1993) is consistent with little or no smooth muscle tone in anesthetized rabbits in control conditions, and with substantial smooth muscle activation following methacholine challenge. The observed local hysteretic boundary motion of the acinar duct would result in irreversible acinar flow fields, which might be important mechanistic contributors to aerosol mixing and deposition deep in the lung.

Kojic, M.; Butler, J. P.; Vlastelica, I.; Stojanovic, B.; Rankovic, V.; Tsuda, A.

2013-01-01

147

ERIC Educational Resources Information Center

For the past 16 years, the blue-collar city of Huntington, West Virginia, has rolled out the red carpet to welcome young wrestlers and their families as old friends. They have come to town chasing the same dream for a spot in what many of them call "The Show". For three days, under the lights of an arena packed with 5,000 fans, the state's best…

Gehring, John

2004-01-01

148

The US Bureau of Mines borehole deformation gauge (BMG) was designed in the early 1960`s to allow rock stress measurements by the overcoring method. Since that time it has become a de facto standard against which the performance of other borehole deformation gauges is often judged. However, during recent in situ stress studies in the Climax Stock at the Nevada Test Site a strange "negative hysteresis" in the order of 300 to 500 microstrains was observed in standard calibration data. Here, the relaxation curve lies below the indentation (compression) curves as if the system were to somehow respond with an energy release. Therefore, a precision micro-indentation apparatus has been designed and used to perform a series of tests allowing a better understanding of the BMG button to cantilever interaction. Results indicate that the hysteresis effect is caused by differential motion between the button base and the cantilever resulting from the geometric motion inherent in the cantilever. The very large apparent hysteresis is mainly caused by cycling opposing cantilevers through the instrument`s entire dynamic range, and the fundamental imprecision inherent in use of the standard micrometers to calibrate the BMG. Laboratory mean hysteresis magnitudes for a polished cantilever typically range from 3 to 25 microstrain for 100 and 1000 microstrain relaxations on 1000 microstrain deflection loops intended to simulate typical field data. The error percentage is thought to remain fairly constant with deformation loop size, and is sufficiently small such that it can be safely ignored. The hysteresis effect can probably be reduced, and instrument stability improved by machining a small 90 degree cone in the cantilever in which a slightly larger mating cone on the base of the indentation button would reside. 5 refs. 26 figs., 1 tab.

Ganow, H.C.

1985-08-01

149

Torque meter aids study of hysteresis motor rings

NASA Technical Reports Server (NTRS)

Torque meter, simulating hysteresis motor operation, allows rotor ring performance characteristics to be analyzed. The meter determines hysteresis motor torque and actual stresses of the ring due to its mechanical situation and rotation, aids in the study of asymmetries or defects in motor rings, and measures rotational hysteresis.

Cole, M.

1967-01-01

150

Hysteresis Loss as a Measure of Metal-Rubber Adhesion

As in the case of reinforcing-filler-induced increase in hysteresis in rubbers, attachment of aluminium (Al) foil onto the surface of a rubber blend (chlorobutyl rubber-carboxylated nitrile rubber) also causes an increase in hysteresis of the rubber. Changes in the hysteresis loss due to Al foil can be correlated with the Al\\/rubber adhesion.

Tinku Bhattacharya; S. K. De

1993-01-01

151

Analysis of wasp-waisted hysteresis loops in magnetic rocks.

The random-field Ising model of hysteresis is generalized to dilute magnets and is solved on a Bethe lattice. Exact expressions for the major and minor hysteresis loops are obtained. In the strongly dilute limit the model provides a simple and useful understanding of the shapes of hysteresis loops in magnetic rock samples. PMID:22400529

Kharwanlang, R S; Shukla, Prabodh

2012-01-01

152

Modeling of Hysteresis Losses Applied to Slotless Permanent Magnet Motors

The paper presents a method to determine hysteresis losses in synchronous permanent magnet (PM) slotless motors. The method comprises four steps : (1) experimental determination of the B-H loop, (2) analytical modeling of the B-H loop by applying different models, (3) analytical modeling of the hysteresis losses, and (4) determination of the hysteresis losses in a synchronous PM motor, and

Pierre-Daniel Pfister; Christian Koechli; Miroslav Markovic; Y. Perriard

2007-01-01

153

Analysis of Hysteresis Losses in Synchronous Permanent Magnet Motors

The paper presents a method to determine hysteresis losses in synchronous permanent magnet (PM) motors. The method comprises four steps: (1) experimental determination of the B-H loop, (2) analytical modeling of the B-H loop by applying different models, (3) analytical modeling of the hysteresis losses, and (4) determination of the hysteresis losses in a synchronous PM motor, and results' verification

P.-D. Pfister; C. Koechli; M. Markovic; Y. Perriard

2006-01-01

154

NASA Astrophysics Data System (ADS)

The Kaldor model-one of the first nonlinear models of macroeconomics-is modified to incorporate a Preisach nonlinearity. The new dynamical system thus created shows highly complicated behaviour. This paper presents a rigorous (computer aided) proof of chaos in this new model, and of the existence of unstable periodic orbits of all minimal periods p>57.

Mc Namara, Hugh A.; Pokrovskii, Alexei V.

2006-02-01

155

Anomalous hysteresis properties of iron films deposited on liquid surfaces

A nearly free sustained iron film system, deposited on silicone oil surfaces by vapor-phase deposition method, has been fabricated and its crystal structure as well as magnetic properties has been studied. Both the temperature-dependent coercivity H{sub c}(T) and exchange anisotropy field H{sub E}(T) of the iron films possess a maximum peak around the critical temperature T{sub crit}=10-15 and 4 K, respectively. Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase below freezing temperature T{sub f}=30-50 K.

Ye Quanlin; Feng Chunmu; Xu Xiaojun; Jin Jinsheng; Xia Agen; Ye Gaoxiang [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Test and Analysis Center, Zhejiang University, Hangzhou 310028 (China); Department of Physics, Zhejiang University, Hangzhou 310027 (China)

2005-07-01

156

Anomalous hysteresis properties of iron films deposited on liquid surfaces

NASA Astrophysics Data System (ADS)

A nearly free sustained iron film system, deposited on silicone oil surfaces by vapor-phase deposition method, has been fabricated and its crystal structure as well as magnetic properties has been studied. Both the temperature-dependent coercivity Hc(T) and exchange anisotropy field HE(T) of the iron films possess a maximum peak around the critical temperature Tcrit=10-15 and 4 K, respectively. Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase below freezing temperature Tf=30-50 K.

Ye, Quan-Lin; Feng, Chun-Mu; Xu, Xiao-Jun; Jin, Jin-Sheng; Xia, A.-Gen; Ye, Gao-Xiang

2005-07-01

157

On the hysteresis of argon adsorption in a uniform closed end slit pore.

We present a molecular simulation study of adsorption and desorption in slit mesopores of uniform width with one end closed and explore the effects of pore dimensions (width and length), temperature and surface affinity on the hysteresis loop: its position, lower and upper closure points, area and shape. Our results show that the metastability, brought about by structural change in the adsorbate, is the reason for the existence of hysteresis, and contrast with reports suggesting that reversibility invariably prevails for adsorption in closed end pores. The shape, area and position of the hysteresis loop are complex functions of pore width, length and temperature. We establish a parametric map of the boundary separating reversible and hysteretic regions. Our simulation results also show a number of interesting observations that have not been previously reported or generally recognised: (1) the fluid within the core of the pore behaves like a bulk liquid as the pore is progressively filled, via the movement of the meniscus from the closed end to the pore mouth, but as the pore fills, the fluid in the core becomes structured, (2) the shape of the meniscus changes as adsorption progresses but is constant during desorption because of the constant thickness of the adsorbed layer in the two-phase region, (3) the hysteresis loop is larger for a longer pore, (4) the area of the hysteresis loop increases with pore width up to a certain width, beyond which it decreases and finally disappears, (5) as temperature approaches the critical hysteresis temperature, the hysteresis loop area decreases, but it retains its Type H1 character. PMID:23746436

Fan, Chunyan; Do, D D; Nicholson, D

2013-09-01

158

Recent work by Bertotti [IEEE Trans. Magn. [bold MAG]-[bold 24], 621 (1988)] and others has shown that it is possible to model the micromagnetic Barkhausen discontinuities at the coercive point using a two-parameter stochastic model. However, the present formulation of the model is restricted to limited regions of the hysteresis curve over which [ital dM]/[ital dH] is approximately constant and when [ital dH]/[ital dt] is held at a constant rate. A natural extension of this model is to take the basic result, in which the level of Barkhausen activity in one time period is related to the activity in the previous time period, and increment it by a small amount which is dependent on the differential permeability. The extension of the model proposed here uses the theory of ferromagnetic hysteresis to determine the differential permeability at any point of the hysteresis loop. The Barkhausen activity is then assumed to vary in proportion to the differential permeability. The resulting model allows the Barkhausen sum of discontinuous changes in magnetization to be modelled around the entire hysteresis loop, leading to an important generalization of the basic model.

Jiles, D.C. (Ames Laboratory, Center for Nondestructive Evaluation, Department of Materials Science and Engineering and Department of Electrical Engineering, Iowa State University, Ames, Iowa 50011 (United States)); Sipahi, L.B. (Ames Laboratory, Center for Nondestructive Evaluation, and Department of Physics, Iowa State University, Ames, Iowa 50011 (United States)); Williams, G. (Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States))

1993-05-15

159

Lift hysteresis at stall as an unsteady boundary-layer phenomenon

NASA Technical Reports Server (NTRS)

Analysis of rotating stall of compressor blade rows requires specification of a dynamic lift curve for the airfoil section at or near stall, presumably including the effect of lift hysteresis. Consideration of the magnus lift of a rotating cylinder suggests performing an unsteady boundary-layer calculation to find the movement of the separation points of an airfoil fixed in a stream of variable incidence. The consideration of the shedding of vorticity into the wake should yield an estimate of lift increment proportional to time rate of change of angle of attack. This increment is the amplitude of the hysteresis loop. An approximate analysis is carried out according to the foregoing ideas for a 6:1 elliptic airfoil at the angle of attack for maximum lift. The assumptions of small perturbations from maximum lift are made, permitting neglect of distributed vorticity in the wake. The calculated hysteresis loop is counterclockwise. Finally, a discussion of the forms of hysteresis loops is presented; and, for small reduced frequency of oscillation, it is concluded that the concept of a viscous "time lag" is appropriate only for harmonic variations of angle of attack with time at mean conditions other than maximum lift.

Moore, Franklin K

1956-01-01

160

Antifreeze proteins (AFPs) are of great importance for applications in cryomedicine or the food industry. They are frequently used to lower the freezing point by preventing the growth of larger ice crystals; thus, it is paramount to determine their thermal hysteretic characteristics. However, the experimental analysis of the thermal hysteresis-an effect that is characteristic for AFPs-remains a challenging process. An easy-to-use test method for measuring the thermal hysteresis of AFPs was developed and tested with the type III AFPs. Traditional methods that have been used until now have their disadvantages and limitations. The new measurement method described in this paper allows detection of the complete cooling, freezing, heating, and melting process in a single measurement. This makes it possible to directly determine the thermal hysteresis as a functional effect of the antifreeze proteins. Measurements of the thermal hysteresis were performed by applying ultrasound to initiate the crystallization process of the antifreeze protein solution. This ultrasound technique also allows a crystallization process to be performed at defined temperature. The demonstrated results were highly reproducible and could be clearly read off the measurement curves. As a future perspective, this enables the design of automatic test devices that can be also miniaturized. PMID:23121544

Gaede-Koehler, Andrea; Kreider, Alexej; Canfield, Peter; Kleemeier, Malte; Grunwald, Ingo

2012-12-01

161

Wetting Hysteresis at the Molecular Scale

NASA Technical Reports Server (NTRS)

The motion of a fluid-fluid-solid contact line on a rough surface is well known to display hysteresis in the contact angle vs. velocity relationship. In order to understand the phenomenon at a fundamental microscopic level, we have conducted molecular dynamics computer simulations of a Wilhelmy plate experiment in which a solid surface is dipped into a liquid bath, and the force-velocity characteristics are measured. We directly observe a systematic variation of force and contact angle with velocity, which is single-valued for the case of an atomically smooth solid surface. In the microscopically rough case, however, we find (as intuitively expected) an open hysteresis loop. Further characterization of the interface dynamics is in progress.

Jin, Wei; Koplik, Joel; Banavar, Jayanth R.

1996-01-01

162

NSDL National Science Digital Library

This is a game about light curves that will test your ability to figure out things about an asteroid from just a graph of its brightness. Astronomers use telescopes to collect light curves - measurements of the brightness of distant asteroids over time. It is part of the Killer Asteroids Web Site. The site also features a background overview of the differences between asteroids and comets, information on different types of asteroids (rubble piles vs monoliths), a discussion of how at risk Earth really is to an asteroid or comet impact, and background information on light curves.

163

Symmetrized curve-straightening

The ‘traditional’ curve-straightening flow is based on one of the standard Sobolev inner products and it is known to break certain symmetries of reflection. The purpose of this paper is to show that there are alternative Riemannian structures on the space of curves that yield flows that preserve symmetries. This feature comes at a price. In one symmetrizing metric the

Anders Linnér

2003-01-01

164

The sorption of organic compounds to natural sorbents is often found to show hysteresis. The objective of this study was to develop an experimental technique based on the use of 14C isotopes to distinguish hysteresis due to experimental artifacts from true hysteresis due to thermodynamically irreversible processes. The study was also designed to investigate causation of true hysteresis (irreversible sorption). The technique determines the rates and the degree of isotope exchange (IE) on equilibrated sorption and desorption points at different constant bulk chemical concentrations. The technique was applied to the sorption of naphthalene (NAPH) on Beulah-Zap lignite, a low rank reference coal composed mainly of kerogen. Sorption of bulk was found to be reversible below 10(-5) g L(-1), but irreversible above 10(-4) g L(-1). Complete isotope exchange on sorption and desorption points that defined an irreversible cycle demonstrated that hysteresis was true. A comparison of normalized uptake and release kinetics of labeled and bulk NAPH at different concentrations revealed slow structural deformation processes of the sorbent during bulk sorption and desorption. This is taken as corroborating evidence for the pore deformation hypothesis of hysteresis in which incoming sorbate molecules induce quasi-reversible changes in the organic matter that lead to different pathways for sorption and desorption. Although unable to rule it out completely, the data demonstrate that physical entrapment of sorbate molecules plays a minor, if any, role to the observed hysteresis in this system. PMID:16245818

Sander, Michael; Pignatello, Joseph J

2005-10-01

165

Comparison of contact angle hysteresis of different probe liquids on the same solid surface.

Advancing and receding contact angles of water, formamide and diiodomethane were measured on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) layers deposited on three different solid supports-glass, mica and poly(methyl methacrylate). Up to five statistical monolayers were deposited on the surfaces by spreading DPPC solution. It was found that even on five statistical DPPC monolayers, the hysteresis of a given liquid depends on the kind of solid support. Also on the same solid support the contact angle hysteresis is different for each probe liquid used. The AFM images show that the heights of roughness of the DPPC films cannot be the primary cause of the observed hysteresis because the heights are too small to cause the observed hystereses. It is believed that the hysteresis is due to the liquid film present right behind the three-phase solid surface/liquid drop/gas (vapour) contact line and the presence of Derjaguin pressure. The value of contact angle hysteresis depends on both the solid surface and liquid properties as well as on intermolecular interactions between them. PMID:23335833

Chibowski, Emil; Jurak, Malgorzata

2013-02-01

166

The flow-duration curve is a cumulative frequency curve that shows the percent of time specified discharges were equaled or exceeded during a given period. It combines in one curve the flow characteristics of a stream throughout the range of discharge, without regard to the sequence of occurrence. If the period upon which the curve is based represents the long-term flow of a stream, the curve may be used to predict the distribution of future flows for water- power, water-supply, and pollution studies. This report shows that differences in geology affect the low-flow ends of flow-duration curves of streams in adjacent basins. Thus, duration curves are useful in appraising the geologic characteristics of drainage basins. A method for adjusting flow-duration curves of short periods to represent long-term conditions is presented. The adjustment is made by correlating the records of a short-term station with those of a long-term station.

Searcy, James Kincheon

1959-01-01

167

Dual carrier traps related hysteresis in organic inverters with polyimide-modified gate-dielectrics

NASA Astrophysics Data System (ADS)

We integrated pentacene- and NN'-diheptyl-3,4,9,10-perylenebiscarboximide-based transistors into an organic complementary metal oxide semiconductor (O-CMOS) whose gate-dielectric surface was modified by polyimide (PI). The hysteresis behaviors in metal-oxide-semiconductors, field-effect transistors, and O-CMOS were reported clearly. Measurements of hysteresis showed that the PI exhibited high trapping and detrapping speeds for charge carriers, including holes and electrons, to result in high performance transistors and O-CMOSs; moreover, the trapping and detrapping speeds were matched. Finally, a PI-modified organic inverter with little hysteresis, low static power dissipation, high noise margins, and switching voltage near VDD/2 was achieved simultaneously.

Chou, Wei-Yang; Yeh, Bo-Liang

2010-04-01

168

Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers. PMID:24784651

Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

2014-04-01

169

NASA Astrophysics Data System (ADS)

Using the smoothed time series of maximum CME speed index for solar cycle 23, it is found that this index, analyzed jointly with six other solar activity indicators, shows a hysteresis phenomenon. The total solar irradiance, coronal index, solar radio flux (10.7 cm), Mg ii core-to-wing ratio, sunspot area, and H? flare index follow different paths for the ascending and the descending phases of solar cycle 23, while a saturation effect exists at the maximum phase of the cycle. However, the separations between the paths are not the same for the different solar activity indicators used: the H? flare index and total solar irradiance depict broad loops, while the Mg ii core-to-wing ratio and sunspot area depict narrow hysteresis loops. The lag times of these indices with respect to the maximum CME speed index are discussed, confirming that the hysteresis represents a clue in the search for physical processes responsible for changing solar emission.

Özgüç, A.; Kilcik, A.; Rozelot, J. P.

2012-12-01

170

Mechano-electric optoisolator transducer with hysteresis

NASA Astrophysics Data System (ADS)

This article presents a theoretical and experimental study of designing a mechano-electric optoisolator transducer with hysteresis. Our research is centred upon designing transducers on the basis of optical sensors, as photoelectric conversions eliminate the influence of electromagnetic disturbances. Conversion of the rotation/translation motions into electric signals is performed with the help of a LED-photoresistor Polaroid optocoupler. The driver of the optocoupler's transmitter module is an independent current source. The signal conditioning circuit is a Schmitt trigger circuit. The device is designed to be applied in the field of automation and mechatronics.

Ciuru?, I. M.; Dimian, M.; Graur, A.

2011-01-01

171

Magnetic hysteresis behavior and microstructure of severely cold-worked and aged Co-Fe-Nb alloy

The magnetic hysteresis behavior of severely cold-worked and aged 85Co-12Fe-3Nb alloy was studied in relation to the microstructure. Magnetic hardening of the alloy can be attributed to the pinning of the domain wall by quasispherical Co3Nb precipitates. Alloys cold worked to 97.8% reduction in area and aged at 700, 800, and 900 °C showed the hysteresis behavior characteristic of inhomogeneous

Yuichi Suzuki; Masato Sagawa; Masanori Okada; Zenzo Henmi

1979-01-01

172

Thermal cycling experiments were conducted on a NiTi shape-memory alloy at different constant applied stresses below the yield strength of the martensite. The mechanical strain response manifested as strain hysteresis loops, whose range was proportional to the applied stress. In situ neutron diffraction experiments show that the strain hysteresis occurs as a result of the establishment of a stress-dependent crystallographic

B. Ye; B. S. Majumdar; I. Dutta

2009-01-01

173

Mechanical hysteresis due to microplasticity in alumina with microcracks

Stress-strain hysteresis in alumina with microcracks has been investigated by a loading–unloading test in the microstrain range around 10 While there remains a permanent strain after the initial loading, steady-state cyclic loading results in a single closed hysteresis loop with a symmetrical shape. Such a stabilized hysteresis loop is responsible for internal friction and can be attributed to the microplasticity

Y. Nishino; H. Ogawa; S. Asano

1992-01-01

174

Optical hysteresis in liquid crystals with helicoidal distributed feedback

A new method is reported whereby optical hysteresis and optical bistability are achieved through resonant absorption of light by an impurity in a cholesteric liquid crystal with a natural helicoidal distributed feedback. The resonant absorption in this system leads to an optical hysteresis at comparatively low light intensities, with a short response time and a simultaneous polarization of light. An implementation of the method is described in which cavity-free optical hysteresis has been achieved with a threshold energy of 10 to the -5th J or less and a response time of 10 to the -8th s. Such a hysteresis may find applications in optical information processing. 7 references.

Zagainova, L.I.; Klimusheva, G.V.; Kryzhanovskii, I.P.; Kukhtarev, N.V.

1985-11-01

175

Hysteresis effects in edge poloidal flow generation

NASA Astrophysics Data System (ADS)

Gas puffing at the edge of the TJ-II stellarator has been used to control the development of an edge poloidal velocity shear layer [1]. Recent experiments have been done to test for hysteresis in the development of the flow. In this work, a numerical transport model is used to examine for hysteresis in the development of an edge poloidal velocity shear layer due to a modeled gas puff. The transport model couples together density, ion temperature, electron temperature, poloidal flow, toroidal flow, radial electric field, and a fluctuation envelope equation which includes a shear-suppression factor. The physics of the model has been modified to include a turbulence growth rate for resistive ballooning modes as well as ion temperature gradient modes. The numerical integration in the model has been changed to a modified Runge-Kutta with adaptive time-stepping. For the cases run with parameters consistent with these TJ-II experiments (only RF heating, no neutral beams), the resistive ballooning mode growth rate is dominant in the edge region. In this work, we present results from a series of cases using parameters that are typical of TJ-II discharges and ramps (both up and down) of an edge density source term used to model a gas puff. The impact of the ramp on the generation of edge poloidal velocity is discussed. [1] C. Hidalgo, et al., Phys. Rev. E 70, 067402 (2004).

Fetscher, B.; Newman, D. E.; Carreras, B. A.; Hidalgo, C.

2005-10-01

176

Corneal hysteresis in patients with dry eye

Purpose To measure corneal hysteresis and intraocular pressure (IOP) in patients with dry eye and to compare with normal subjects. Methods This cross-sectional study consists of 70 eyes of 40 patients with dry eye (group 1) and 75 eyes of 40 normal subjects (group 2). Eyes were diagnosed as dry eye or normal according to the clinical symptoms, biomicroscopical evaluation, and Schirmer test. Corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure (IOPcc) were measured by the Ocular Response Analyser (ORA). Results Mean CH values were 10.56±0.25?mm?Hg and 10.34±0.26?mm?Hg, mean CRF values were 10.75±0.28?mm?Hg and 10.70±0.28?mm?Hg, mean CCT values were 542±3.20??m and 543±3.89??m in group 1 and group 2, respectively. There was no statistically significant difference between the groups for these three parameters. IOPcc values measured with ORA were 15.73±0.36?mm?Hg in group 1 and 16.60±0.33?mm?Hg in group 2, and there was no statistically significant difference between the two groups. Conclusions Corneal biomechanical parameters such as CH and CRF are not influenced in dry eye. Also statistical difference was not found between the two groups according to CCT and IOPcc values.

Firat, P G; Doganay, S

2011-01-01

177

Dependence of Barkhausen Pattern Reproducibility on Hysteresis Loop Size

NASA Astrophysics Data System (ADS)

Barkhausen noise from the ferromagnetic alloy Fe_21Co_64B_15 (which shows many statistical properties characteristic of a single-degree-of-freedom model(Durin, Bertotti, and Magni, Fractals 3, 351 (1995))) showed reproducible structure on succesive minor hysteresis loops, as has been found in other materials(Urbach, Madison, and Markert, PRL 75, 276 (1995))^, (Petta, Weissman, and O'Brien, PRE, 54, R1029 (1996)). However, on full loops extending to saturation, we could detect no reproducible structure anywhere in the loop. This indicates that the detailed statistics do not directly reflect the underlying quenched disorder of the material, but rather involve some self-organization of domain walls, capable of following multiple pathways after being reset by saturating fields.

Petta, J. R.; Weissman, M. B.

1997-03-01

178

A new model is developed to describe the properties of a Josephson junction critical current in a strong magnetic field. A comparison with experiments shows the possibility of the existence of a surface barrier to the Abrikosov vortex motion in YBCO-124 metalceramics. Characteristic features of this barrier appear in the abnormal hysteresis loop of the transport critical current.

A. I. D'Yachenko

1993-01-01

179

Theory and simulation of angular hysteresis on planar surfaces.

A simple model is proposed to simulate contact angle hysteresis in drops on a planar surface. The model is based on assuming a friction force acting on the triple contact line in such a way that the contact line keeps fixed for contact angles comprised between the advancing angle and the receding one and is allowed to move in order to avoid angles outside this interval. The model is straightforwardly applied to axisymmetric drops for which a simple solution of the Young-Laplace equation can be obtained. A variation of the method has also been implemented for nonaxisymmetric drops by resorting to the public-domain "Surface Evolver" software. Comparison with experiments shows the excellent performance of the model. PMID:22050087

Santos, M J; White, J A

2011-12-20

180

Structure, morphology and melting hysteresis of ion-implanted nanocrystals

NASA Astrophysics Data System (ADS)

Investigations of nanosized metal and semimetal inclusions produced by ion implantation in aluminium are reviewed. The inclusions are from 1 nm to 15 nm in size and contain from 80 to 100 000 atoms. Embedded crystallites, which are topotactically aligned with the surrounding matrix, may not be produced in this size range by any other method. The inclusions offer unique possibilities for study of the influence of interfaces on the crystal structure of the inclusions as well as on their melting and solidification behaviour. Studies are made with transmission electron microscopy (TEM), electron- and X-ray diffraction and in situ RBS-channeling measurements. Bi, Cd, In, Pb and Tl inclusions all show a substantial melting/solidification temperature hysteresis, which, in all cases except for Bi, is placed around the bulk melting temperature, while bismuth melts below that temperature.

Andersen, Hans Henrik; Johnson, Erik

1995-12-01

181

Study of a Low-Inertia Hysteresis Motor.

National Technical Information Service (NTIS)

A rotary-drive vibratory-output two-degrees-of-freedom gyro was utilized in a rotor structure of an axial air gap hysteresis motor containing anisotropic barium ferrite and Al-alloy plates. The barium ferrite was used for its large hysteresis loop, small ...

H. Yamada

1975-01-01

182

Circuit measures hysteresis loop areas at 30 Hz

NASA Technical Reports Server (NTRS)

Analog circuit measures hysteresis loop areas as a function of time during fatigue testing of specimens subjected to sinusoidal tension-compression stresses at a frequency of Hz. When the sinusoidal stress signal is multiplied by the strain signal, the dc signal is proportional to hysteresis loop area.

Hoffman, C.; Spilo, D.

1967-01-01

183

Preisach modeling of piezoceramic and shape memory alloy hysteresis

Smart materials such as piezoceramics and shape memory alloys (SMAs) exhibit significant hysteresis and in order to estimate the effect on open and closed loop control a suitable model is needed. One promising candidate is the Preisach independent domain hysteresis model that is characterized by the congruent minor loop and wiping out properties. Comparable minor loop and decaying oscillation test

Declan Hughes; John T. Wen

1995-01-01

184

Lumped-circuit models for nonlinear inductors exhibiting hysteresis loops

A new mathematical model of dynamic hysteresis loops is presented. The model is completely specified by two strictly monotonically increasing functions: a restoring function f(.) and a dissipation function g(.). Simple procedures are given for constructing these two functions so that the resulting model will simulate a given hysteresis loop exactly. The model is shown to exhibit many important hysteretic

L. Chua; K. Stromsmoe

1970-01-01

185

Sensorless evaluation of asymmetric hysteresis loops of ferromagnetic materials

The sensorless determination of the dynamic hysteresis loop of magnetic materials, and in particular those of magnetic plates, can be obtained under ac symmetric conditions in a relatively simple way. This paper proposes a new digital method and instrument for the sensorless evaluation of the dynamic hysteresis loop under ac asymmetric conditions, in the presence of a dc polarization of

Loredana Cristaldi; Alessandro Ferrero; Massimo Lazzaroni; Adriano P. Morando

2003-01-01

186

Minor Hysteresis Loop in Fe Metal and Alloys

The minor hysteresis loops were measured with increasing magnetic field amplitude Ha step by step and analyzed in Fe single crystal, polycrystalline metals and A533B steel. We have defined several new magnetic properties in the minor loops: they are pseudo magnetization {Ba}*, pseudo coercive force {Hc}*, pseudo remanence {BR}*, pseudo hysteresis loss {WF}*, pseudo remanence work {WR}*, and three pseudo

Seiki Takahashi; Lefu Zhang

2004-01-01

187

Corneal hysteresis following descemetorhexis with endokeratoplasty: early results.

The corneal biomechanical properties following descemetorhexis with endokeratoplasty (DXEK) and in normal subjects were studied in 100 eyes (12 DXEK and 88 age-matched normal subjects). Corneal hysteresis measurements were significantly lower in DXEK vs normal subjects. DXEK has a direct effect on corneal hysteresis and corneal biomechanical properties of the human cornea. PMID:17914199

John, Thomas; Taylor, David A; Shimmyo, Mitsugu; Siskowski, Bruce E

2007-01-01

188

Impact of relative permeability hysteresis on geological CO2 storage

Relative permeabilities are the key descriptors in classical formulations of multiphase flow in porous media. Experimental evidence and an analysis of pore-scale physics demonstrate conclusively that relative permeabilities are not single functions of fluid saturations and that they display strong hysteresis effects. In this paper, we evaluate the relevance of relative permeability hysteresis when modeling geological CO2 sequestration processes. Here

R. Juanes; E. J. Spiteri; F. M. Orr Jr; M. J. Blunt

2006-01-01

189

International Workshop on Multi-Rate Processes and Hysteresis

We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can

Michael P Mortell; Robert E OMalley; Alexei Pokrovskii; Dmitrii Rachinskii; Vladimir A Sobolev

2008-01-01

190

PREFACE: International Workshop on Multi-Rate Processes and Hysteresis

We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can

Michael P. Mortell; Robert E. O'Malley; Alexei Pokrovskii; Dmitrii Rachinskii; Vladimir A. Sobolev

2008-01-01

191

Energy-based hysteresis model for magnetostrictive transducers

This paper addresses the modeling of hysteresis in magnetostrictive transducers in the context of control applications that require an accurate characterization of the relation between input currents and strains output by the transducer. This relation typically exhibits significant nonlinearities and hysteresis because of inherent properties of magnetostrictive materials. The characterization considered here is based on the Jiles-Atherton mean field model

F. T. Calkins; R. C. Smith; A. B. Flatau

2000-01-01

192

Potbellies, wasp-waists, and superparamagnetism in magnetic hysteresis

Because the response of a magnetic substance to an applied field depends strongly on the physical properties of the material, much can be learned by monitoring that response through what is known as a ``magnetic hysteresis loop.'' The measurements are rapid and quickly becoming part of the standard set of tools supporting paleomagnetic research. Yet the interpretation of hysteresis loops

L. Tauxe; T. A. T. Mullender; T. Pick

1996-01-01

193

Hysteresis behavior of the anisotropic quantum Heisenberg model

NASA Astrophysics Data System (ADS)

The effect of the anisotropy in the exchange interaction on the hysteresis loops within the anisotropic quantum Heisenberg model has been investigated with the effective field theory for two spin cluster. Particular attention has been devoted on the behavior of the hysteresis loop area, coercive field and remanent magnetization with the anisotropy in the exchange interaction for both ferromagnetic and paramagnetic phases.

Ak?nc?, Ümit

2013-10-01

194

Hysteresis in Thin-Film Rechargeable Lithium Batteries.

National Technical Information Service (NTIS)

Discharge - charge cycling of thin-film rechargeable lithium batteries with an amorphous or nanocrystalline LiXMn2.Y04 cathode reveals evidence for a true hysteresis in the lithium insertion reaction. This is compared with an apparent hysteresis attribute...

J. B. Bates N. J. Dudney C. D. Evans F. X. Hart

1999-01-01

195

A permanent magnet hysteresis hybrid synchronous motor for electric vehicles

This paper presents the design, analysis and PWM vector control of a hybrid permanent magnet hysteresis synchronous (PMHS) motor with a view to improve the performances of motors for electric vehicle applications. This hybrid design combines the advantageous performance features of both conventional hysteresis motors and permanent magnet motors. Electrical equivalent circuits of the PMHS motor are developed for both

M. Azizur Rahman; Ruifeng Qin

1997-01-01

196

Starting and synchronization of permanent magnet hysteresis motors

This paper presents the design and application of permanent magnets in hysteresis motors with a view to improve the overall performances of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines advantageous performance features of both typical permanent magnet motors and conventional hysteresis motors. Machine models for steady

M. A. Rahman; Ruifeng Qin

1994-01-01

197

Transient performance analysis for permanent magnet hysteresis synchronous motor

The combination of hysteresis and permanent magnet materials in the rotor of a self-starting synchronous motor makes the motor analysis very difficult due to its inherent nonlinearity. This paper presents the simulation results of the transient performance of permanent magnet hysteresis synchronous (PMHS) motors. The major feature in this study is to combine the time-stepping finite element technique with the

Kazumi Kurihara; M. Azizur Rahman

2002-01-01

198

Magnetic equivalent circuit of PM hysteresis synchronous motor

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous motor (PMHS). The hybrid synchronous motor consists of 36% cobalt steel hysteresis alloys with neodymium iron boron permanent magnets to improve the overall performances of such a motor. Based on the magnetic equivalent circuit, the control strategy of the PMHS motor is developed. Experimental results confirm the

R. Qin; M. A. Rahman

2003-01-01

199

Starting and synchronization of permanent magnet hysteresis motors

This paper presents the design, analysis, and application of permanent magnets in a hysteresis motor with a view to improve the overall performance of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines the advantageous performance features of both typical permanent magnet motors and conventional hysteresis motors. The

M. Azizur Rahman; Ruifeng Qin

1996-01-01

200

A permanent magnet hysteresis hybrid motor drive for electric vehicles

This paper presents the design, analysis and PWM vector control of a hybrid permanent magnet hysteresis synchronous motor with a view to improve the performances of the motors for electric vehicle application. This hybrid design combines the advantageous performance features of both the conventional hysteresis motors and the permanent magnet motors. A PWM vector control simulation and experimental results for

M. A. Rahman; Ruifeng Qin

1996-01-01

201

Magnetic equivalent circuit of PM hysteresis synchronous motor

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous (PMHS) motor. The hybrid synchronous motor consists of 30% Cobalt-steel hysteresis alloys Neodymium Iron Boron (NdFeB) permanent magnets to improve the overall performances of motors.

Ruifeng Qin; M. A. Rahman

2003-01-01

202

The Effect of Liquid Structure on Contact Angle Hysteresis.

National Technical Information Service (NTIS)

Contact angle hysteresis was measured for a variety of liquids on condensed monolayers of 17-(perfluoroheptyl)-heptadecanoic acid adsorbed on polished chromium. The hysteresis was shown to be simply related to the molecular volume of the liquid and to res...

C. O. Timmons W. A. Zisman

1966-01-01

203

Windmill speed limiting system utilizing hysteresis

A windmill speed limiting device is provided to prevent the windmill blades from going too fast during conditions of heavy winds. In order to slow down the windmill blades, the tips of the blades are turned relative to the main blade portion at high speeds. After the tips are turned, the windmill blade must return to a safe speed before the tips are returned to their normal position. A hysteresis effect by which the tip portions are rotated to their normal angular position in alignment with the main blade portion is implemented by means of a cam track, a pivot point below the center of the blade and a central spring loaded drum to which each of the blades are connected.

Barnes, D.R.

1983-02-22

204

A Hysteresis Model for Piezoceramic Materials

NASA Technical Reports Server (NTRS)

This paper addresses the modeling of nonlinear constitutive relations and hysteresis inherent to piezoceramic materials at moderate to high drive levels. Such models are, necessary to realize the, full potential of the materials in high performance control applications, and a necessary prerequisite is the development of techniques which permit control implementation. The approach employed here is based on the qualification of reversible and irreversible domain wall motion in response to applied electric fields. A comparison with experimental data illustrates that because the resulting ODE model is physics-based, it can be employed for both characterization and prediction of polarization levels throughout the range of actuator operation. Finally, the ODE formulation is amenable to inversion which facilitates the development of an inverse compensator for linear control design.

Smith, Ralph C.; Ounaies, Zoubeida

1999-01-01

205

A theory of double hysteresis for ferroelectric crystals

NASA Astrophysics Data System (ADS)

A ferroelectric crystal is known to exhibit the usual single hysteresis below its Curie point TC, but above this temperature its electric displacement D versus electric field E plot tends to form double loops. We first point out that there is a fundamental difference in the formation of double loops from the single one: the single loop is formed solely by polar reorientation, but in the double loops the right branch of its upper loop is formed by phase transition and only the left branch is formed by polar reorientation (the process is reversed for the lower loop). In this study we take the view that both cubic-->tetragonal phase transition and the polar reorientation of ferroelectric domain are thermodynamics-driving process and use this concept to develop a micromechanics-based thermodynamic model to simulate the double hysteresis behavior of the crystal. We first derive the thermodynamic driving force for both spontaneous polarization and domain switch at a given level of temperature, stress, electric field, and new domain concentration c1 and then establish the kinetic equations for domain growth. A dual-phase homogenization theory is then introduced to calculate the overall electric displacement and mechanical strain of the crystal. This approach differs from the classical Landau-Ginzburg-Devonshire theory in at least two significant aspects: (i) it is developed with a micromechanics-based thermodynamics principle, and (ii) it can provide the evolution of new domain concentration. The developed theory is applied to a BaTiO3 crystal. The calculated results show a single loop below its TC and double loops above it but with a diminishing width at higher temperature. Furthermore, the longitudinal strain ? vs E loop is found to exhibit the usual butterfly-shape relation below TC, but above it the loop shows a new, overlapping double-well picture. Good agreement with available test data is also observed.

Srivastava, N.; Weng, G. J.

2006-03-01

206

National Technical Information Service (NTIS)

Hysteresis in smart actuators presents a challenge in control of these actuators. A fundamental idea to cope with hysteresis is inverse compensation. In this paper we study modeling, identification and inverse control of hysteresis in smart actuators thro...

X. Tan J. S. Baras

2002-01-01

207

Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model

NASA Astrophysics Data System (ADS)

In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller.

Li, Pengzhi; Yan, Feng; Ge, Chuan; Zhang, Mingchao

2012-08-01

208

Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model.

In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller. PMID:22938339

Li, Pengzhi; Yan, Feng; Ge, Chuan; Zhang, Mingchao

2012-08-01

209

Approximate Bézier curves by cubic LN curves

In order to derive the offset curves by using cubic Bézier curves with a linear field of normal vectors (the so-called LN Bézier curves) more efficiently, three methods for approximating degree n Bézier curves by cubic LN Bézier curves are considered, which includes two traditional methods and one new method based on Hausdorff distance. The approximation based on shifting control

Wei-Xian Huang; Cong-Jian Jin; Guo-Jin Wang

2011-01-01

210

Highly curved microchannel plates

NASA Technical Reports Server (NTRS)

Several spherically curved microchannel plate (MCP) stack configurations were studied as part of an ongoing astrophysical detector development program, and as part of the development of the ALEXIS satellite payload. MCP pairs with surface radii of curvature as small as 7 cm, and diameters up to 46 mm have been evaluated. The experiments show that the gain (greater than 1.5 x 10 exp 7) and background characteristics (about 0.5 events/sq cm per sec) of highly curved MCP stacks are in general equivalent to the performance achieved with flat MCP stacks of similar configuration. However, gain variations across the curved MCP's due to variations in the channel length to diameter ratio are observed. The overall pulse height distribution of a highly curved surface MCP stack (greater than 50 percent FWHM) is thus broader than its flat counterpart (less than 30 percent). Preconditioning of curved MCP stacks gives comparable results to flat MCP stacks, but it also decreases the overall gain variations. Flat fields of curved MCP stacks have the same general characteristics as flat MCP stacks.

Siegmund, O. H. W.; Cully, S.; Warren, J.; Gaines, G. A.; Priedhorsky, W.; Bloch, J.

1990-01-01

211

Hysteresis prediction for piezoceramic actuator systems using Preisach models

NASA Astrophysics Data System (ADS)

Hysteresis is a form of nonlinearity that is present in piezoceramic microactuator systems. A methodology to predict influence of hysteresis on system performance is valuable when these actuators are employed as part of closed loop motion control systems. In this work, an existing phenomenological approach (Preisach models) is investigated for piezoceramic systems. Hysteresis in a piezoceramic system is experimentally documented initially for a bounding operating condition of a cyclic electric potential. The limiting hysteresis loop has a positive turning point of +100 V and a negative turning point of -100 V. Hysteretic behavior for various operating conditions within this bounding loop (i.e. minor hysteresis loops) is then predicted using a moving Preisach model. In addition, hysteresis effects are analytically predicted when a constant mechanical load and a cyclic electric potential are applied simultaneously, using two inputs Preisach model. Experimental data are also presented for the minor hysteresis loops at different positive and negative turning points. Predictions using Preisach models agreed well with the experimental results, particularly when the minor loops are closer to the bounding loop.

Sreeram, Puduhai N.; Naganathan, Nagi G.

1994-05-01

212

Modelling hysteresis in magnetically ordered materials

NASA Astrophysics Data System (ADS)

This thesis presents a generalized version of the Preisach model of hysteresis which is designed to describe the temperature dependence and field dependence of the irreversible response of magnetically ordered materials everywhere below their critical temperature Tc. The model decomposes the magnetizing process into a sequence of Barkhausen events, each of which is represented by a double well potential with moment mu two states ? = +/-mu, a dissipation energy Wd = mu hc and a stored energy Ws = 2muhi. A given magnetic material is characterized by an ensemble of Barkhausen elements with a distribution of characteristic fields p(hc, hi). The distribution is allowed to vary with temperature in order to reflect intrinsic variations with temperature of the anisotropy and pinning mechanisms, in such a way that the coercive field distribution collapses into a delta-function delta( hc) as T approaches Tc from below. Thermal fluctuations are represented by a thermal viscosity field h*T = (kBT/mu)ln( texp/tau0). The model was used to simulate numerically various standard experimental response functions, including the temperature dependence of the zero field cooled moment in a fixed applied field ha, the temperature dependence of the field cooled moment in a fixed applied field, initial magnetizing and major hysteresis loop isotherms, and remanences, and the influence of each model parameter on the magnetic response functions was studied systematically. The model simulation sidentified the ratio eta of the mean zero temperature dissipation barrier W¯d(0) to the critical thermal fluctuation energy Wc = k BTcln(texp/tau 0) ass an important parameter which influences the principal structural characteristics of the response, and which can be used to classify materials as fluctuation-dominated or anisotropy-dominated. The model was applied to the analysis of the measured response functions five systems, two nanoparticulate systems, Fe/SiO 2 and NiFe2O 4, which were fluctuation-dominated, and three ferromagnetic perovskites SrRuO3, La0.5Sr 0.5-CoO3, and La0.7 Sr0.3MnO3, which were anisotropy-dominated. The analysis yielded the spectrum of Barkhausen characteristic fields p(hc, hi, T) and the Barkhausen moment mu(T), from which it is possible to reconstruct a physical picture of the evolution of the Barkhausen free energy barriers with temperature, as well as some description of the reversible component of the response.

Song, Tiancheng

2003-06-01

213

Understanding the hysteresis loop conundrum in pharmacokinetic / pharmacodynamic relationships.

Hysteresis loops are phenomena that sometimes are encountered in the analysis of pharmacokinetic and pharmacodynamic relationships spanning from pre-clinical to clinical studies. When hysteresis occurs it provides insight into the complexity of drug action and disposition that can be encountered. Hysteresis loops suggest that the relationship between drug concentration and the effect being measured is not a simple direct relationship, but may have an inherent time delay and disequilibrium, which may be the result of metabolites, the consequence of changes in pharmacodynamics or the use of a non-specific assay or may involve an indirect relationship. Counter-clockwise hysteresis has been generally defined as the process in which effect can increase with time for a given drug concentration, while in the case of clockwise hysteresis the measured effect decreases with time for a given drug concentration. Hysteresis loops can occur as a consequence of a number of different pharmacokinetic and pharmacodynamic mechanisms including tolerance, distributional delay, feedback regulation, input and output rate changes, agonistic or antagonistic active metabolites, uptake into active site, slow receptor kinetics, delayed or modified activity, time-dependent protein binding and the use of racemic drugs among other factors. In this review, each of these various causes of hysteresis loops are discussed, with incorporation of relevant examples of drugs demonstrating these relationships for illustrative purposes. Furthermore, the effect that pharmaceutical formulation has on the occurrence and potential change in direction of the hysteresis loop, and the major pharmacokinetic / pharmacodynamic modeling approaches utilized to collapse and model hysteresis are detailed. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page. PMID:24735761

Louizos, Christopher; Yáñez, Jaime A; Forrest, M Laird; Davies, Neal M

2014-01-01

214

Bistable hysteresis and resistance switching in hydrogen-gold junctions

NASA Astrophysics Data System (ADS)

Current-voltage characteristics of H2-Au molecular junctions exhibit intriguing steps around a characteristic voltage of Vs?40mV . Surprisingly, we find that a hysteresis is connected to these steps with a typical time scale >10ms . This time constant scales linearly with the power dissipated in the junction beyond an off-set power Ps=IVs . We propose that the hysteresis is related to vibrational heating of both the molecule in the junction and a set of surrounding hydrogen molecules. Remarkably, by stretching the junction the hysteresis’ characteristic time becomes >days . We demonstrate that reliable switchable devices can be built from such junctions.

Trouwborst, M. L.; Huisman, E. H.; van der Molen, S. J.; van Wees, B. J.

2009-08-01

215

Drag force measurement: A means for determining hysteresis loss

A method for determining hysteresis losses in thin strips of soft magnetic materials is described. It is based on the measurement of a drag force which arises with the movement of the sample through the strong field existing in the space near a permanent magnet. Not associated with macro eddy currents, the force is shown to originate from the magnetic hysteresis of the material, having, in fact, an amplitude equal to the product of hysteresis loss and the area of the sample cross section. Correlation within 18% with the measurements made by conventional methods is shown for a wide range of experimental materials.

Garshelis, Ivan J.; Tollens, Stijn P. L.; Kari, Ryan J.; Vandenbossche, Lode P.; Dupre, Luc R. [Magnova, Inc., Pittsfield, Massachusetts 01201 and MagCanica, Inc., San Diego, California 92117 (United States); MagCanica, Inc., San Diego, California 92117 (United States); Department of Electrical Energy, Systems and Automation, Ghent University, Ghent B-9000 (Belgium)

2006-04-15

216

Static measurements of slender delta wing rolling moment hysteresis

NASA Technical Reports Server (NTRS)

Slender delta wing planforms are susceptible to self-induced roll oscillations due to aerodynamic hysteresis during the limit cycle roll oscillation. Test results are presented which clearly establish that the static rolling moment hysteresis has a damping character; hysteresis tends to be greater when, due to either wing roll or side slip, the vortex burst moves back and forth over the wing trailing edge. These data are an indirect indication of the damping role of the vortex burst during limit cycle roll oscillations.

Katz, Joseph; Levin, Daniel

1991-01-01

217

Sorption isotherms have been widely used to assess the heavy metal retention characteristics of soil particles. Desorption behavior of the retained metals, however, usually differ from that of sorption, leading to a lack of coincidence in the experimentally obtained sorption and desorption isotherms. In this study, we examine the nonsingularity of cadmium (Cd) sorption-desorption isotherms, to check the possible hysteresis and reversibility phenomena, in aqueous palygorskite, sepiolite and calcite systems. Sorption of Cd was carried out using a 24-h batch equilibration experiment with eight different Cd solution concentrations, equivalent to 20-100% of maximum sorption capacity of each mineral. Immediately after sorption, desorption took place using successive dilution method with five consecutive desorption steps. Both Cd sorption and desorption data were adequately described by Freundlich equation (0.81

Shirvani, Mehran; Kalbasi, Mahmoud; Shariatmadari, Hosein; Nourbakhsh, Farshid; Najafi, Bijan

2006-12-01

218

Hysteresis and nonlinear elasticity in rocks

The purpose of this paper is to describe a theory of the propagation of elastic waves in hysteretic nonlinear elastic materials, e.g., rock. In the next section, we introduce the Priesach-Mayergoyz (P-M) model [6,7] of hysteretic systems and adapt it to describe the hysteretic mesoscopic elastic units (HMEU) determining the elastic properties of a rock. We combine the P-M model with effective medium theory (EMT) [8] to find the elastic response of a rock that has experienced a specified pressure history. Next, we consider elastic wave propagation in a hysteretic nonlinear elastic system governed by a history dependent equation of state. We consider one-dimensional propagation of compressional waves. The equation of motion for the longitudinal displacement field contains the same hysteretic nonlinear interactions that characterize the equation of state. We solve the equation of motion using the Green function technique developed by McCall [9]. This solution lets us identify the qualitative features in harmonic generation that are signatures of nonlinearity and hysteresis.

McCall, K.R.; Guyer, R.A.

1993-12-01

219

National Technical Information Service (NTIS)

The observation of the SN1987A light curve shows the latter to be highly unusual. The rise of the optical curve within a few hours and the very rapid UV decline shows a strong cooling in the early phase. The luminosity plateau was quite low, about 3 to 4 ...

R. Schaeffer

1987-01-01

220

On the question of hysteresis in Hall magnetohydrodynamic reconnection

Controversy has been raised regarding the cause of hysteresis, or bistability, of solutions to the equations that govern the geometry of the reconnection region in Hall magnetohydrodynamic (MHD) systems. This brief communication presents a comparison of the frameworks within which this controversy has arisen and illustrates that the Hall MHD hysteresis originally discovered numerically by Cassak et al. [Phys. Rev. Lett. 95, 235002 (2005)] is a different phenomenon from that recently reported by Zocco et al. [Phys. Plasmas 16, 110703 (2009)] on the basis of analysis and simulations in electron MHD with finite electron inertia. We demonstrate that the analytic prediction of hysteresis in EMHD does not describe or explain the hysteresis originally reported in Hall MHD, which is shown to persist even in the absence of electron inertia.

Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin [Center for Integrated Computation and Analysis of Reconnection and Turbulence, University of New Hampshire, Space Science Center, Durham, New Hampshire 03824 (United States)

2010-11-15

221

Energy-Based Hysteresis Model for Magnetostrictive Transducers.

National Technical Information Service (NTIS)

This paper addresses the modeling of hysteresis in magnetostrictive transducers. This is considered in the context of control applications which require an accurate characterization of the relation between input currents and strains output by the transduc...

F. T. Calkins R. C. Smith A. B. Flatau

1997-01-01

222

Hysteresis as a Marker for Complex, Overlapping Landscapes in Proteins

Topologically complex proteins fold by multiple routes as a result of hard-to-fold regions of the proteins. Oftentimes these regions are introduced into the protein scaffold for function and increase frustration in the otherwise smooth-funneled landscape. Interestingly, while functional regions add complexity to folding landscapes, they may also contribute to a unique behavior referred to as hysteresis. While hysteresis is predicted to be rare, it is observed in various proteins, including proteins containing a unique peptide cyclization to form a fluorescent chromophore as well as proteins containing a knotted topology in their native fold. Here, hysteresis is demonstrated to be a consequence of the decoupling of unfolding events from the isomerization or hula-twist of a chromophore in one protein and the untying of the knot in a second protein system. The question now is- can hysteresis be a marker for the interplay of landscapes where complex folding and functional regions overlap?

Andrews, Benjamin T.; Capraro, Dominique T.; Sulkowska, Joanna I.; Onuchic, Jose N.; Jennings, Patricia A.

2013-01-01

223

Low-Hysteresis Flow-Through Wind-Tunnel Balance

NASA Technical Reports Server (NTRS)

Improved flow-through wind-tunnel balance includes features minimizing both spurious force readings caused by internal pressurized flow and mechanical hysteresis. Symmetrical forces caused by internal flow cancelled.

Kunz, N.; Luna, P. M.; Roberts, A. C.; Smith, R. C.; Horne, W. L.; Smith, K. M.

1992-01-01

224

PREFACE: International Workshop on Hysteresis & Multi-scale Asymptotics

NASA Astrophysics Data System (ADS)

An International Workshop on Hysteresis & Multi-scale Asymptotics was held at University College Cork, Ireland on March 17-21, 2004. It brought together about 40 active scientists in the areas of dynamical systems with hysteresis and singular perturbations to analyse these phenomena which occur in many industrial, physical and economic systems. The scientific programme of the Workshop can be downloaded from the homepage http://euclid.ucc.ie/hamsa2004.htm. This collection of invited papers is based on the programme of the workshop whose main goal was to analyse and to demonstrate an interaction between theories of systems with multiple scales and systems with hysteresis (and between the 'multi-scale' and 'hysteresis' research communities) as far as possible. To fully understand the paths from singular perturbations to hysteresis and from hysteresis to singular perturbations will continue to involve much work and intense interdisciplinary interactions among experts in the two areas. We mention also two previous workshops: International Workshop on Relaxation Oscillations & Hysteresis, University College Cork, Ireland, April 1-6, 2002. The related collection, edited by us, was published as 'Singular Perturbations and Hysteresis', SIAM, Philadelphia, 2005. http://www.ucc.ie/ucc/depts/physics/ins/roh2002.htm International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics, University College Cork, Ireland, April 5-6, 2001. A collection of invited papers has been published as a special issue of Proceedings of the Russian Academy of Natural Sciences: Nonlinear dynamics of laser and reacting systems, Vol. 5, 2001, No 1 and 2 (edited by Vladimir Gol'dstein, Alexei Pokrovskii and Vladimir Sobolev), and is also available online at http://euclid.ucc.ie/appliedmath/gmna2001/ProcGMNA2001Full.pdf Finally, we wish to gratefully acknowledge the support of the School of Mathematical Sciences and the Boole Centre for Research in Informatics, University College Cork.

Mortell, Michael; O'Malley, Robert E.; Pokrovskii, Alexei; Sobolev, Vladimir

2005-01-01

225

Hysteresis as an implicit prior in tactile spatial decision making.

Perceptual decisions not only depend on the incoming information from sensory systems but constitute a combination of current sensory evidence and internally accumulated information from past encounters. Although recent evidence emphasizes the fundamental role of prior knowledge for perceptual decision making, only few studies have quantified the relevance of such priors on perceptual decisions and examined their interplay with other decision-relevant factors, such as the stimulus properties. In the present study we asked whether hysteresis, describing the stability of a percept despite a change in stimulus property and known to occur at perceptual thresholds, also acts as a form of an implicit prior in tactile spatial decision making, supporting the stability of a decision across successively presented random stimuli (i.e., decision hysteresis). We applied a variant of the classical 2-point discrimination task and found that hysteresis influenced perceptual decision making: Participants were more likely to decide 'same' rather than 'different' on successively presented pin distances. In a direct comparison between the influence of applied pin distances (explicit stimulus property) and hysteresis, we found that on average, stimulus property explained significantly more variance of participants' decisions than hysteresis. However, when focusing on pin distances at threshold, we found a trend for hysteresis to explain more variance. Furthermore, the less variance was explained by the pin distance on a given decision, the more variance was explained by hysteresis, and vice versa. Our findings suggest that hysteresis acts as an implicit prior in tactile spatial decision making that becomes increasingly important when explicit stimulus properties provide decreasing evidence. PMID:24587045

Thiel, Sabrina D; Bitzer, Sebastian; Nierhaus, Till; Kalberlah, Christian; Preusser, Sven; Neumann, Jane; Nikulin, Vadim V; van der Meer, Elke; Villringer, Arno; Pleger, Burkhard

2014-01-01

226

Stabilization of supercooled fluids by thermal hysteresis proteins.

It has been reported that thermal hysteresis proteins found in many cold-hardy, freeze-avoiding arthropods stabilize their supercooled body fluids. We give evidence that fish antifreeze proteins, which also produce thermal hysteresis, bind to and reduce the efficiency of heterogenous nucleation sites, rather than binding to embryonic ice nuclei. We discuss both possible mechanisms for stabilization of supercooled body fluids and also describe a new method for measuring and defining the supercooling point of small volumes of liquid.

Wilson, P W; Leader, J P

1995-01-01

227

Generalized hysteresis current controller for three-level inverter topologies

This paper analyzes the generalized hysteresis current control algorithm for three level inverter topologies. The inverter topologies considered are H-bridge, diode clamped and capacitor clamped three level inverters. It is shown that the switching frequency for the proposed hysteresis algorithm can be estimated using an empirical relation. The algorithm can be directly implemented for the H-bridge and diode clamped three-level

Shweta Gautam; Rajesh Gupta

2012-01-01

228

Hysteresis in Thin-Film Rechargeable Lithium Batteries

Discharge - charge cycling of thin-film rechargeable lithium batteries with an amorphous or nanocrystalline LiXMn2.Y04 cathode reveals evidence for a true hysteresis in the lithium insertion reaction. This is compared with an apparent hysteresis attributed to a kinetically hindered phase transition near 3 V for batteries with either a crystalline or a nanocrystalline LiJ@Yo4 cathode.

Bates, J.B.; Dudney, N.J.; Evans, C.D.; Hart, F.X.

1999-04-25

229

Transient performance analysis for permanent-magnet hysteresis synchronous motor

The combination of hysteresis and permanent-magnet materials in the rotor of a self-starting synchronous motor makes the motor analysis very difficult due to its inherent nonlinearity. This paper presents the simulation results of the transient performance of permanent magnet hysteresis synchronous (PMHS) motors. The major feature in this study is to combine the time-stepping finite-element technique with the model for

Kazumi Kurihara; M. Azizur Rahman

2004-01-01

230

Aileron roll hysteresis effects on entry of space shuttle orbiter

NASA Technical Reports Server (NTRS)

Six-degree-of-freedom simulations of the space shuttle orbiter entry with control hysteresis were conducted on the NASA Langley Research Center interactive simulator known as the automatic reentry flight dynamics simulator. These simulations revealed that the vehicle can tolerate control hysteresis producing a + or - 50 percent change in the nominal aileron roll characteristics and an offset in the nominal characteristics equivalent to a + or - 5 deg aileron deflection with little increase in the reaction control system's fuel consumption.

Powell, R. W.

1977-01-01

231

Modeling and characterization for polarization hysteresis of ferroelectric polymers

We present a modeling and simulation based study for the polarization hysteresis of ferroelectric polymers. A 2- dimensional finite element device-level model was implemented using SILVACO's ATLAS device simulator to generate the polarization hysteresis characteristics for the recently reported experimental data on Au\\/Poly(vinylidene fluoride- trifluoroethylene)\\/Au metal-insulator-metal (MIM) device. The simulated polarization dependence characteristics in the P(VDF-TrFE) thin-film were predicted from

Bikash Shrestha; Ron Pieper; Wudyalew Wondmagegn; Nikhil Satyala

2011-01-01

232

Adhesion hysteresis and friction at nanometer and micrometer lengths

Comparisons between adhesion hysteresis and friction at nanometer and micrometer length scales were investigated experimentally and theoretically. Nanoscale adhesion hysteresis was measured using the ultrasonic force microscopy (UFM) on mica, calcite, and a few metallic samples (Pt, Au, Cu, Zn, Ti, and Fe). Obtained adhesion hysteresis ranged between 4x10{sup -19} and 4x10{sup -18} J. At the microscale a similar setup with a nanoindenter was used and the same samples were investigated. Adhesion hysteresis measured at the microscale ranged between 8x10{sup -17} and 14x10{sup -17} J. Friction was investigated via lateral force microscopy, as well as by scratch tests done with the nanoindenter. Numerical simulations based on the UFM model as well as established theories of contact mechanics studied qualitative dependencies of adhesion hysteresis on experimental parameters. Quantitative relations between adhesion hysteresis and friction were obtained through an analytic model relying on elastic and adhesive properties of the contact. The model agreed with measurements and simulations.

Szoszkiewicz, Robert; Bhushan, Bharat; Huey, Bryan D.; Kulik, Andrzej J.; Gremaud, Gerard [Georgia Institute of Technology, School of Physics, 837 State Street, Atlanta, Georgia 30332 (United States); Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), Ohio State University, Columbus, Ohio 43210 (United States); Institute of Material Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Institute of Physics of Complex Matter, EPFL, CH-1015 Lausanne (Switzerland)

2006-01-01

233

Influence of magnetostriction on hysteresis loss of electrical steel sheet

NASA Astrophysics Data System (ADS)

To reveal influence of magnetostriction on hysteresis loss of electrical steel sheet, hysteresis loss and magnetostriction of non-oriented electrical steel sheets (NOs) with various Si and Al content and grain size and grain oriented electrical steel sheet (GO) were measured under compressive or tensile stress. Here, Si and Al content and stress were focused on as the way to change magnetostriction. Stress direction and magnetizing direction were parallel to the rolling direction. Following three main results were obtained. The first is hysteresis loss of NO with same grain size which increased with magnetostriction independently of Si and Al content and stress. The second is hysteresis loss of NO was larger than that of GO under same magnetostriction. The third is hysteresis loss of NO at magnetostriction of zero was inversely proportional to grain size. Even if the grain size of NO increased to be similar size of GO without changing texture, the hysteresis loss of NO at magnetostriction of zero would be larger than that of GO because of the difference in texture.

Tada, Hirotoshi; Fujimura, Hiroshi; Yashiki, Hiroyoshi

2013-01-01

234

NASA Astrophysics Data System (ADS)

This paper proposes a rate-independent hysteresis compensator for a stacked PZT (lead zirconate titanate) actuator. From a congruency-based hysteresis (CBH) model which is derived from the inherent properties of this actuator, especially the congruency, a feedforward compensator associated with it is developed. The formulation of the proposed compensator is based on an assumption that the inverse operator also possesses the same properties as the CBH model does. This implies that the compensator also possesses properties such as the wiped-out loop closing between the consecutive control points and congruency. Consequently, the expressions for the compensator can be conducted by exploiting the equations for the CBH model in two cases of monotonic increase and monotonic decrease of input excitation. In order to assess the performance of the compensator, several experiments in both open-loop and closed-loop controls are undertaken. In the open-loop control experiment, the performance of the feedforward compensator using the CBH model is compared with the classical Preisach model-based one in three cases of reference waveforms. In the closed-loop control experiment, the proposed compensator is incorporated into a PID (proportional-integral-derivative) control system and the performance of this integrated system is then evaluated and compared to that of the PID with and without compensator.

Nguyen, Phuong-Bac; Choi, Seung-Bok

2012-01-01

235

Adaptive control with hysteresis estimation and compensation using RFNN for piezo-actuator

Because the control performance of a piezoactuator is always severely deteriorated due to hysteresis effect, an adaptive control with hysteresis estimation and compensation using recurrent fuzzy neural network (RFNN) is proposed in this study to improve the control performance of the piezo-actuator. A new hysteresis model by modifying and parameterizing the hysteresis friction model is proposed. Then, the overall dynamics

Faa-Jeng Lin; Hsin-Jang Shieh; Po-Kai Huang; Li-Tao Teng

2006-01-01

236

Average normalisations of elliptic curves

Ciet, Quisquater, and Sica have recently shown that every elliptic curve E over a finite field Fp is isomorphic to a curve y2 = x3 +ax+b with a and b of size O(p3\\/4). In this paper, we show that almost all elliptic curves satisfy the stronger bound O(p2\\/3). The problem is motivated by cryptographic considerations.

William D. Banks; Igor E. Shparlinski

2002-01-01

237

Lithium insertion and extraction for high-capacity disordered carbons with large hysteresis

Disordered carbons heat-treated from 550 to 1000 °C containing hydrogen atoms showed high specific capacities with large hysteresis in the potential when used as anodes in lithium-ion cells. The lithium storage mechanism in the disordered carbons has been investigated by the charge-discharge test, X-ray diffraction (XRD) and solid-state 7Li NMR measurements. Variation of the layer spacing of the disordered carbon

Norio Takami; Asako Satoh; Takahisa Ohsaki; Motoya Kanda

1997-01-01

238

Origin of hysteresis in the transfer characteristic of carbon nanotube field effect transistor

NASA Astrophysics Data System (ADS)

Using electrostatic force microscopy, we show direct evidence of charge injection at the carbon nanotube-SiO2 interface leading to the appearance of hysteresis. The dynamic screening effect of the injected charges is revealed step by step. Further temperature dependent tests also demonstrate the effect of SiO2 surface chemistry. Furthermore, we conclude that it is not practical to use such a device for memory application because of data retention and storage density issues.

Ong, H. G.; Cheah, J. W.; Zou, X.; Li, B.; Cao, X. H.; Tantang, H.; Li, L.-J.; Zhang, H.; Han, G. C.; Wang, J.

2011-07-01

239

A new theory of condensation in an open end slit pore, based on the concept of temperature dependent undulation, at the interface separating the adsorbed phase and the gas-like region, is presented. The theory, describes, for the first time, the microscopic origin of the critical hysteresis temperature and the critical hysteresis pore size, properties which are not accessible to any classical theories. PMID:24826906

Fan, Chunyan; Zeng, Yonghong; Do, D D; Nicholson, D

2014-05-28

240

On rational Minkowski Pythagorean hodograph curves

Minkowski Pythagorean hodograph curves are polynomial curves with polynomial speed, measured with respect to Minkowski norm. Curves of this special class are particularly well suited for represe nting medial axis transforms of planar domains. In the present paper we generalize this poly- nomial class to a rational class of curves in Minkowski 3-space. We show that any rational Minkowski Pythagorean

Jirí Kosinka; Miroslav Lávicka

2010-01-01

241

Origin of gate hysteresis in p-type Si-doped AlGaAs/GaAs heterostructures

NASA Astrophysics Data System (ADS)

Gate instability/hysteresis in modulation-doped p-type AlGaAs/GaAs heterostructures impedes the development of nanoscale hole devices, which are of interest for topics from quantum computing to novel spin physics. We present an extended study conducted using custom-grown, matched modulation-doped n-type and p-type heterostructures, with and without insulated gates, aimed at understanding the origin of the hysteresis. We show the hysteresis is not due to the inherent “leakiness” of gates on p-type heterostructures, as commonly believed. Instead, hysteresis arises from a combination of GaAs surface-state trapping and charge migration in the doping layer. Our results provide insights into the physics of Si acceptors in AlGaAs/GaAs heterostructures, including widely debated acceptor complexes such as Si-X. We propose methods for mitigating the gate hysteresis, including poisoning the modulation-doping layer with deep-trapping centers (e.g., by codoping with transition metal species) and replacing the Schottky gates with degenerately doped semiconductor gates to screen the conducting channel from GaAs surface states.

Burke, A. M.; Waddington, D. E. J.; Carrad, D. J.; Lyttleton, R. W.; Tan, H. H.; Reece, P. J.; Klochan, O.; Hamilton, A. R.; Rai, A.; Reuter, D.; Wieck, A. D.; Micolich, A. P.

2012-10-01

242

Hysteresis and the dynamic phase transition in thin ferromagnetic films

Hysteresis and the nonequilibrium dynamic phase transition in thin magnetic films subject to an oscillatory external field have been studied by Monte Carlo simulation. The model under investigation is a classical Heisenberg spin system with a bilinear exchange anisotropy {Lambda} in a planar thin film geometry with competing surface fields. The film exhibits a nonequilibrium phase transition between dynamically ordered and dynamically disordered phases characterized by a critical temperature T{sub cd}, whose location is determined by the amplitude H{sub 0} and frequency {omega} of the applied oscillatory field. In the presence of competing surface fields the critical temperature of the ferromagnetic-paramagnetic transition for the film is suppressed from the bulk system value T{sub c} to the interface localization-delocalization temperature T{sub ci}. The simulations show that in general T{sub cd}{lt}T{sub ci} for the model film. The profile of the time-dependent layer magnetization across the film shows that the dynamically ordered and dynamically disordered phases coexist within the film for T{lt}T{sub cd}. In the presence of competing surface fields, the dynamically ordered phase is localized at one surface of the film.

Jang, Hyunbum; Grimson, Malcolm J.

2001-06-01

243

ERIC Educational Resources Information Center

We show that inside every triangle the locus of points satisfying a natural proportionality relationship is a parabola and go on to describe how this triangle-parabola relationship was used by Archimedes to find the area between a line and a parabola.

Swain, Gordon A.

2013-01-01

244

To use e-textiles as a strain-resistance sensor they need to be both elastic and conductive. Three kinds of elastic-conductive webbings, including flat, tubular, and belt webbings, made of Lycra fiber and carbon coated polyamide fiber, were used in this study. The strain-resistance properties of the webbings were evaluated in stretch-recovery tests and measured within 30% strain. It was found that tensile hysteresis and contact resistance significantly influence the tensile elasticity and the resistance sensitivity of the webbings. The results showed that the webbing structure definitely contributes to the tensile hysteresis and contact resistance. The smaller the friction is among the yarns in the belt webbing, the smaller the tensile hysteresis loss. However the close proximity of the conductive yarns in flat and tubular webbings results in a lower contact resistance.

Shyr, Tien-Wei; Shie, Jing-Wen; Jhuang, Yan-Er

2011-01-01

245

Magnetic hysteresis of p(+) and He-3(2+) irradiated melt-textured YBa2Cu3O(7-delta)

NASA Technical Reports Server (NTRS)

We have measured the magnetic hysteresis loops and temperature dependent trapped fields in melt-textured YBa2Cu3O(7-delta) samples before and after p(+) and He-3(2+) irradiation using a Hall effect magnetometer (HEM) as well as a commercial vibrating sample magnetometer (VSM). For proper He-3(2+) fluence, the critical current density may be enhanced by a factor of 10. Calculations based on various critical state models show that before the irradiation, the hysteresis loops can be well accounted for by a critical current density of a modified power law field dependence. After the irradiation, the best fit has been achieved by using an exponential form. Jc and its field dependence deduced from HEM hysteresis loops are in good agreement with those deduced from the VSM loops, suggesting that the Hall effect magnetometer can be conveniently used to characterize bulk high Tc oxide superconductors.

Song, S. N.; Liu, J.; Chen, I. G.; Weinstein, Roy

1992-01-01

246

Microstructures in Low-Hysteresis Shape Memory Alloys: Scaling Regimes and Optimal Needle Shapes

NASA Astrophysics Data System (ADS)

For certain martensitic phase transformations, one observes a close relation between the width of the thermal hysteresis and the compatibility of two phases. This observation forms the basis of a theory of hysteresis that assigns an important role to the microstructures in the transition layer and their energetics (Zhang et al., Acta Mater 57(15), 4332-4352,

Zwicknagl, Barbara

2014-08-01

247

NASA Astrophysics Data System (ADS)

The paper deals with the numerical analysis of a rotational single sheet tester with round-shaped specimen (RRSST) which is now under construction. The measurement setup consists of an induction motor the rotor of which has been removed, and its windings have been replaced to a special two phase one which can generate homogeneous magnetic field inside the motor. The two orthogonal components of the magnetic field intensity and of the magnetic flux density vectors can be measured by H-coils and B-coils, respectively. The Finite Element Method (FEM) with the T, ?-? potential formulation has been applied in the simulations. The vector hysteresis property of the specimen has been approximated by the vector Preisach model. Finally, the nonlinear problem has been solved by the fixed-point technique. The aim of the present work is to focus on the design aspects of this kind of measurement system.

Kuczmann, Miklós

2008-02-01

248

NASA Astrophysics Data System (ADS)

In order to investigate the feasible application of a permanent magnet-high-temperature superconductor (PM-HTS) interaction maglev system to a maglev train or a space vehicle launcher, we have constructed a demonstration maglev test vehicle. The force dissipation and damping of the maglev vehicle against external disturbances are studied in a wide range of amplitudes and frequencies by using a sine vibration testing set-up. The dynamic levitation force shows a typical hysteresis behavior, and the force loss is regarded as the hysteresis loss, which is believed to be due to flux motions in superconductors. In this study, we find that the hysteresis loss has weak frequency dependence at small amplitudes and that the dependence increases as the amplitude grows. To analyze the damping properties of the maglev vehicle at different field cooling (FC) conditions, we also employ a transient vibration testing technique. The maglev vehicle shows a very weak damping behavior, and the damping is almost unaffected by the trapped flux of the HTSs in different FC conditions, which is believed to be attributed to the strong pinning in melt-textured HTSs.

Yang, Wenjiang; Liu, Yu; Wen, Zheng; Chen, Xiaodong; Duan, Yi

2008-01-01

249

Hysteresis and relaxation in granular permanent magnets

NASA Astrophysics Data System (ADS)

Some nontrivial aspects of the magnetic and structural characterization of hard-magnetic nanoparticles are investigated. Dilute ensembles are well-described by mean-field theory, although there is an asymmetry between exchange and magnetostatic interaction fields. Corrections to the mean-field approximation are caused by cooperative effects and have the character of Onsager reaction fields, which are much stronger in micromagnetism than in atomic-scale magnetism. The slow dynamics of zero-field-cooled (ZFC) magnetization curves is strongly affected by the particles' magnetic anisotropy, which reduces the corresponding energy-barrier height from 25 to 19.1 kBT.

Skomski, Ralph; Balamurugan, B.; George, Tom A.; Chipara, Mircea; Wei, Xiao-Hui; Shield, Jeff E.; Sellmyer, D. J.

2012-04-01

250

Magnetic hysteresis minor loops in Fe single crystal

NASA Astrophysics Data System (ADS)

Magnetic hysteresis minor loops were measured with step by step increase of the magnetic field amplitude, Ha, in plastically deformed Fe single crystal. In order to analyse minor loops in connection with the lattice defects, we defined some magnetic parameters, such as the pseudo-coercive force, Hc*, and the differential susceptibility under the pseudo-coercive force khgrH*. Hc*, for instance, is the magnetic field where the magnetization becomes zero in minor loops. In this work, we found the relationship 2Hc* = Ha to hold over a fairly wide Ha range. These parameters are important for representing Bloch wall displacement and the potential energy. The parameters are remarkably sensitive to lattice defects in the field range below the coercive force Hc. The relation of 1/khgrH* and Hc* shows better sensitivity—90 times higher than that for Hc—for revealing information on dislocations. In the minor loop measurement, for getting full information on dislocations it is sufficient to have Ha = 400 A m-1.

Takahashi, S.; Zhang, L.; Ueda, T.

2003-11-01

251

PREFACE: International Workshop on Multi-Rate Processes and Hysteresis

NASA Astrophysics Data System (ADS)

We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can be considered as limit cases of time relaxation processes, or admit an approximation by a differential equation which is singular with respect to a particular parameter. However, the amount of interaction between practitioners of theories of systems with time relaxation and systems with hysteresis (and between the `relaxation' and `hysteresis' research communities) is still low, and cross-fertilization is small. In recent years Ireland has become a home for a series of prestigious International Workshops in Singular Perturbations and Hysteresis: International Workshop on Multi-rate Processes and Hysteresis (University College Cork, Ireland, 3-8 April 2006). Proceedings are published in Journal of Physics: Conference Series, volume 55. See further information at http://euclid.ucc.ie/murphys2008.htm International Workshop on Hysteresis and Multi-scale Asymptotics (University College Cork, Ireland, 17-21 March 2004). Proceedings are published in Journal of Physics: Conference Series, volume 22. See further information at http://euclid.ucc.ie/murphys2006.htm International Workshop on Relaxation Oscillations and Hysteresis (University College Cork, Ireland, 1-6 April 2002). The related collection of invited lectures, was published as a volume Singular Perturbations and Hysteresis, SIAM, Philadelphia, 2005. See further information at http://euclid.ucc.ie/hamsa2004.htm International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics (University College Cork, Ireland, 5-5 April 2001). A collection of invited papers has been published as a special issue of Proceedings of the Russian Academy of Natural Sciences: Nonlinear dynamics of laser and reacting systems, and is available online at http://www.ins.ucc.ie/roh2002.htm. See further information at http://www.ins.ucc.ie/roh2002.htm Among the aims of these workshops were to bring together leading experts in singular perturbations and hysteresis phenomena in applied problems; to discuss important problems in areas such as reacting systems, semiconductor lasers, shock phenomena in economic modelling, fluid mechanics, etc with an emphasis on hysteresis and singular perturbations; to learn and to share modern techniques in areas of common interest. The `International Workshop on Multi-Rate Processes and Hysteresis' (University College Cork, Ireland, April 3-8, 2006) brought together more than 70 scientists (including more than 10 students), actively researching in the areas of dynamical systems with hysteresis and singular perturbations, to analyze those phenomena that occur in many industrial, physical and economic systems. The countries represented at the Workshop included Czech Republic, England, France, Germany, Hungary, Ireland, Israel, Italy, Poland, Romania, Russia, Scotland, South Africa, Switzerland and USA. All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing. The Workshop has been sponsored by Science Foundation Ireland (SFI), KE Consulting group, Drexel University, Philadelphia, USA, University College Cork (UCC), Boole Centre for Research in Informatics, UCC, Cork, School of Mathematical Sciences, UCC, Cork, Irish Mathematical Society, Tyndall National Institute, Cork, University of Limerick, Cork Institute of Technology, and Heineken. The supportive affiliation of the European Geophysics Society, International Association of Hydrological Sciences, and Laboratoire Poncelet is grateful

Mortell, Michael P.; O'Malley, Robert E.; Pokrovskii, Alexei; Rachinskii, Dmitrii; Sobolev, Vladimir A.

2008-07-01

252

Hysteresis in the production of force by larval Dipteran muscle.

We describe neuromuscular hysteresis - the dependence of muscle force on recent motoneuron activity - in the body wall muscles of larval Sarcophaga bullata and Drosophila melanogaster. In semi-intact preparations, isometric force produced by a train of nerve impulses at a constant rate was significantly less than that produced by the same train of stimuli with a brief (200 ms) high-frequency burst of impulses interspersed. Elevated force did not decay back to predicted values after the burst but instead remained high throughout the duration of the stimulus train. The increased force was not due to a change in excitatory junction potentials (EJPs); EJP voltage and time course before and after the high-frequency burst were not statistically different. Single muscle and semi-intact preparations exhibited hysteresis similarly, suggesting that connective tissues of the origin or insertion are not crucial to the mechanism of hysteresis. Hysteresis was greatest at low motoneuron rates - yielding a approximately 100% increase over predicted values based on constant-rate stimulation alone - and decreased as impulse rate increased. We modulated motoneuron frequency rhythmically across rates and cycle periods similar to those observed during kinematic analysis of larval crawling. Positive force hysteresis was also evident within these more physiological activation parameters. PMID:20581278

Paterson, Bethany A; Anikin, Ilya Marko; Krans, Jacob L

2010-07-15

253

Weak hysteresis in a simplified model of the L-H transition

A simple one-field L-H transition model is studied in detail, analytically and numerically. The dynamical system consists of three equations coupling the drift wave turbulence level, zonal flow speed, and the pressure gradient. The fourth component, i.e., the mean shear velocity, is slaved to the pressure gradient. Bursting behavior, characteristic for predator-prey models of the drift wave - zonal flow interaction, is recovered near the transition to the quiescent H-mode (QH) and occurs as strongly nonlinear relaxation oscillations. The latter, in turn, arise as a result of Hopf bifurcation (limit cycle) of an intermediate fixed point (between the L- and H-modes). The system is shown to remain at the QH-mode fixed point even after the heating rate is decreased below the bifurcation point (i.e., hysteresis, subcritical bifurcation), but the basin of attraction of the QH-mode shrinks rapidly with decreasing power. This suggests that the hysteresis in the H-L transition may be less than that expected from S-curve models. Nevertheless, it is demonstrated that by shaping the heating rate temporal profile, one can reduce the average power required for the transition to the QH-mode.

Malkov, M. A.; Diamond, P. H. [Center for Astrophysics and Space Sciences and Department of Physics, University of California, San Diego, La Jolla, California 92093-0424 (United States)

2009-01-15

254

Hysteresis free SiO2/InSb metal-insulator-semiconductor diodes

NASA Astrophysics Data System (ADS)

Hysteresis free capacitance-voltage (C-V) characteristics of SiO2/InSb metal-insulator-semiconductor (MIS) diodes are attained by introducing an in situ Br vapor etching technique into the fabrication process. Interface state density is also reduced by using this technique. It is found that following vapor etching, MIS C-V characteristics are strongly dependent on both the SiO2 film deposition temperature and oxygen flow rate. The optimum condition for SiO2 film deposition to obtain hysteresis free C-V curves and an interface state density of equal to or less than 10 to the 11th per sq cm per eV is determined for InSb MIS diodes. The area of the typical optimum conditions for MIS diodes is located in the oxygen flow rate range of 5-6 cc/min and the deposition temperature range of 200-210 C. The efractive indices of SiO2 films are 1.44-1.45, the breakdown field strengths are more than 2,000,000 V/cm, and the dielectric constans for 1 MHz are typically 4.7 at 77 K, respectively.

Okamura, M.; Minakata, M.

1985-03-01

255

Dynamic Hysteresis in Cyclic Deformation of Crystalline Solids

NASA Astrophysics Data System (ADS)

The hysteresis or internal friction in the deformation of crystalline solids stressed cyclically is studied from the viewpoint of collective dislocation dynamics. Stress-controlled simulations of a dislocation dynamics model at various loading frequencies and amplitudes are performed to study the stress-strain rate hysteresis. The hysteresis loop areas exhibit a maximum at a characteristic frequency and a power law frequency dependence in the low frequency limit, with the power law exponent exhibiting two regimes, corresponding to the jammed and the yielding or moving phases of the system, respectively. The first of these phases of the system exhibits nontrivial critical-like viscoelastic dynamics, crossing over to intermittent viscoplastic deformation for higher stress amplitudes.

Laurson, Lasse; Alava, Mikko J.

2012-10-01

256

Hysteresis of Freedericksz transition in confined light beams

The effect of the transverse confinement of an incident light beam on the hysteresis of light-induced Freedericksz transition in a nematic liquid crystal cell is considered. The thresholds of the orientational instability of the director with an increase and decrease in the light beam's intensity are calculated numerically in relation to its transverse size. The hysteresis loop width is shown to change nonmonotonically with an increase in the transverse dimension. In contrast to a homogeneous light beam, the hysteresis existence region is determined not only by the parameter (K{sub 3} - K{sub 1})/K{sub 3} but also by the parameter K{sub 2}/K{sub 3}. With an increase in the transverse beam size, the critical values of the parameter (K{sub 3} - K{sub 1})/K{sub 3} increase, while those of the parameter K{sub 2}/K{sub 3} decrease.

Ledney, M. F., E-mail: ledney@univ.kiev.ua; Tarnavsky, A. S. [Kyiv National Taras Shevchenko University (Ukraine)

2010-03-15

257

Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids.

Dynamic hysteresis phenomena are widespread in physical sciences and describe the complex behavior of systems driven out of equilibrium by a periodic forcing. We use here paramagnetic colloids above a stripe-patterned garnet film as the model system to study dynamic hysteresis, the latter induced when the particles are periodically translated by an oscillating magnetic field. In contrast to the expected behavior for a bistable system, we observe that the area of the hysteresis loop decreases by increasing the driving frequency and reduces to zero for frequencies higher than 5-7s(-1). To explain the experimental results, we develop a simple model based on an overdamped Brownian particle driven by a periodic potential with an oscillating amplitude. PMID:23848669

Tierno, Pietro; Johansen, Tom H; Sancho, J M

2013-06-01

258

Direct recursive identification of the Preisach hysteresis density function

NASA Astrophysics Data System (ADS)

In this paper, a novel direct method of recursive identification of the Preisach hysteresis density function is proposed. Using the discrete dynamic Preisach model, which is a state-space realization of the classical scalar Preisach model, the method is designed based on the output increment error. After giving the general formulation, the identification scheme implemented for a discretized Preisach plane is introduced and evaluated through the use of numerical simulations. Two cases of Gaussian mixtures are considered for mapping the hysteresis system to be identified. The parameter convergence is shown for a low-pass filtered white-noise input. Further, the proposed identification method is applied to a magnetism-related application example, where the flux linkage hysteresis of a proportional solenoid is assumed from the measurements, and then the inverse of a standard demagnetization procedure is utilized as the identification sequence.

Ruderman, Michael

2013-12-01

259

Very low hysteresis organic thin-film transistors

NASA Astrophysics Data System (ADS)

Very low hysteresis vanadyl-phthalocyanine/para-sexiphenyl thin-film transistors (TFTs) have been fabricated using benzocyclobutenone (BCBO) derivatives/tantalum pentoxide (Ta2O5)/BCBO triple gate dielectrics. The field effect mobility, on/off current ratio and threshold voltage of organic TFTs are 0.45 cm2 V-1 s-1, 3.5 × 104 and -6.8 V, respectively. To clarify the mechanism of hysteresis, devices with different dielectrics have been studied. It is found that the bottom BCBO derivatives (contact with a gate electrode) block the electron injection from a gate electrode to dielectrics. The top BCBO derivatives are also found to improve the properties of interface between the dielectrics and organic semiconductor. Then very low hysteresis devices are obtained.

Li, Chunhong; Pan, Feng; Zhu, Feng; Song, De; Wang, He; Yan, Donghang

2009-08-01

260

Sinusoidal input describing function for hysteresis followed by elementary backlash

NASA Technical Reports Server (NTRS)

The author proposes a new sinusoidal input describing function which accounts for the serial combination of hysteresis followed by elementary backlash in a single nonlinear element. The output of the hysteresis element drives the elementary backlash element. Various analytical forms of the describing function are given, depending on the a/A ratio, where a is the half width of the hysteresis band or backlash gap, and A is the amplitude of the assumed input sinusoid, and on the value of the parameter representing the fraction of a attributed to the backlash characteristic. The negative inverse describing function is plotted on a gain-phase plot, and it is seen that a relatively small amount of backlash leads to domination of the backlash character in the describing function. The extent of the region of the gain-phase plane covered by the describing function is such as to guarantee some form of limit cycle behavior in most closed-loop systems.

Ringland, R. F.

1976-01-01

261

An Energy-Based Hysteresis Model for Magnetostrictive Transducers

NASA Technical Reports Server (NTRS)

This paper addresses the modeling of hysteresis in magnetostrictive transducers. This is considered in the context of control applications which require an accurate characterization of the relation between input currents and strains output by the transducer. This relation typically exhibits significant nonlinearities and hysteresis due to inherent properties of magnetostrictive materials. The characterization considered here is based upon the Jiles-Atherton mean field model for ferromagnetic hysteresis in combination with a quadratic moment rotation model for magnetostriction. As demonstrated through comparison with experimental data, the magnetization model very adequately quantifies both major and minor loops under various operating conditions. The combined model can then be used to accurately characterize output strains at moderate drive levels. The advantages to this model lie in the small number (six) of required parameters and the flexibility it exhibits in a variety of operating conditions.

Calkins, F. T.; Smith, R. C.; Flatau, A. B.

1997-01-01

262

Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators

NASA Technical Reports Server (NTRS)

A phenomenological characterization of hysteresis in magnetostrictive materials is presented. Such hysteresis is due to both the driving magnetic fields and stress relations within the material and is significant throughout, most of the drive range of magnetostrictive transducers. An accurate characterization of the hysteresis and material nonlinearities is necessary, to fully utilize the actuator/sensor capabilities of the magnetostrictive materials. Such a characterization is made here in the context of generalized Preisach operators. This yields a framework amenable to proving the well-posedness of structural models that incorporate the magnetostrictive transducers. It also provides a natural setting in which to develop practical approximation techniques. An example illustrating this framework in the context of a Timoshenko beam model is presented.

Smith, R. C.

1997-01-01

263

Inkjet printing of precisely defined features using contact-angle hysteresis.

Motivated by the process of inkjet printing of electronics, we study experimentally and theoretically the processes limiting the printing of sharply defined, equilibrium corners. Using a non-volatile ionic liquid, we inkjet print squares with rounded corners on a substrate of roughened, display-grade glass. We show experimentally that with increasing roughness, corner radius decreases, allowing more precisely defined features to be printed. To interpret these results in terms of contact-angle hysteresis (difference between the advancing and retreating contact angles ?A and ?R), we implement the following model with the Surface Evolver program. With drop volume fixed, we minimize drop surface energy subject to a prescribed contact line. We identify ?A and ?R as the minimum and maximum contact angles around the drop perimeter. We find that with decreasing corner fidelity, contact-angle hysteresis also decreases. We are thus able to infer ?R from the corner radius of printed features. We conclude that increasing contact-angle hysteresis allows the printing of more precisely defined features. PMID:23570870

Soltman, Dan; Smith, Ben; Morris, S J S; Subramanian, Vivek

2013-06-15

264

Nonequilibrium hysteresis and Wien effect water dissociation at a bipolar membrane

NASA Astrophysics Data System (ADS)

As in electrochemical cyclic voltammetry, time-periodic reverse voltage bias across a bipolar membrane is shown to exhibit hysteresis due to transient effects. This is due to the incomplete depletion of mobile ions, at the junction between the membranes, within two adjoining polarized layers; the layer thickness depends on the applied voltage and the surface charge densities. Experiments show that the hysteresis consists of an Ohmic linear rise in the total current with respect to the voltage, followed by a decay of the current. A limiting current is established for a long period when all the mobile ions are depleted from the polarized layer. If the resulting high field within the two polarized layers is sufficiently large, water dissociation occurs to produce proton and hydroxyl traveling wave fronts which contribute to another large jump in the current. We use numerical simulation and asymptotic analysis to interpret the experimental results and to estimate the amplitude of the transient hysteresis and the water-dissociation current.

Conroy, D. T.; Craster, R. V.; Matar, O. K.; Cheng, L.-J.; Chang, H.-C.

2012-11-01

265

Observations of hysteresis in solar cycle variations among seven solar activity indicators

NASA Technical Reports Server (NTRS)

We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study, we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar emission at various wavelengths.

Bachmann, Kurt T.; White, Oran R.

1994-01-01

266

A memory device using an organic field effect transistor (OFET) with copper phthalocyanine (CuPc) as active material was fabricated and studied. For this purpose, SiO2 dielectric surface was modified with a disordered self assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) molecule which was found to induce large disorder in CuPc film thereby generating more traps for charge carriers. Drain current-drain voltage characteristics at zero gate voltage exhibited large hysteresis which was not observed in OFET devices with ordered OTS monolayer modified and unmodified SiO2 dielectrics. The extent of hysteresis and drain current on/off ratio, reading voltage etc. were found to be dependent on the sweep rate/step voltage employed during scanning. Highest hysteresis with on/off ratio of about 240 was obtained for an optimum step voltage of 2 V while it decreased with further reduction in the same. This was attributed to the longer scanning time leading to release of trapped carriers during forward scan itself. The OFET device was found to exhibit excellent memory retention capability where OFF and ON current measured for about 2 hours after stressing the device at write and erase voltages showed good retention of on/off ratio. PMID:24738406

Padma, N; Saxena, Vibha; Sudarsan, V; Rava, Harshil; Sen, Shaswati

2014-06-01

267

Modelling eddy currents and hysteresis in a transformer laminate

A Cauer circuit model of a transformer laminate is presented. It considers saturation, eddy currents and hysteresis. The simulation results agree to experiments with an Epstein frame in the 10--200 Hz range. The paper includes a description of a computationally fast hysteresis model with few adjustable parameters and a physical approach to derive the Cauer circuit. The model can be used under various time-transient conditions and can easily be implemented into a larger system in a circuit simulation package, such as Saber, to study a transformer`s interaction with switching overvoltages, for example.

Holmberg, P.; Bergqvist, A. [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Electric Power Engineering] [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Electric Power Engineering; Engdahl, G. [ABB Corporate Research, Vaesteraas (Sweden). Dept. of Power Engineering] [ABB Corporate Research, Vaesteraas (Sweden). Dept. of Power Engineering

1997-03-01

268

Domain Nucleation and Hysteresis Loop Shape in Piezoresponse Force Spectroscopy

Electromechanical hysteresis loop measurements in piezoresponse force microscopy (PFM) [piezoresponse force spectroscopy (PFS)] have emerged as a powerful technique for probing ferroelectric switching behavior on the nanoscale. Interpretation of PFS data requires the relationship between the domain parameters and PFM signal to be established. Here, the authors analyze the switching process using modified point charge model. The charge parameters are selected to reproduce tip-induced surface potential and tip radius of curvature. The relationship between geometric parameters of semiellipsoidal domain and PFM signal is derived using linear Green's function theory. The role of domain nucleation on hysteresis loop is established.

Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Kalinin, Sergei V [ORNL

2006-01-01

269

A survey on hysteresis modeling, identification and control

NASA Astrophysics Data System (ADS)

The various mathematical models for hysteresis such as Preisach, Krasnosel'skii-Pokrovskii (KP), Prandtl-Ishlinskii (PI), Maxwell-Slip, Bouc-Wen and Duhem are surveyed in terms of their applications in modeling, control and identification of dynamical systems. In the first step, the classical formalisms of the models are presented to the reader, and more broadly, the utilization of the classical models is considered for development of more comprehensive models and appropriate controllers for corresponding systems. In addition, the authors attempt to encourage the reader to follow the existing mathematical models of hysteresis to resolve the open problems.

Hassani, Vahid; Tjahjowidodo, Tegoeh; Do, Thanh Nho

2014-12-01

270

Large-scale separation and hysteresis in cascades

NASA Technical Reports Server (NTRS)

An approach using a two-dimensional thin aerofoil, allied with the theory of viscous bluff-body separation, is used to study the initial cross-over from massive separation to an attached flow in a single-row unstaggered cascade. Analytic solutions are developed for the limit of small cascade-spacing. From the analytic solutions several interesting features of the cascade are examined, including multiple-solution branches and multiple regions of hysteresis. In addition, numerical results are presented for several selected aerofoils. Some of the aerofoils are found to contain markedly enlarged regions of hysteresis for certain critical cascade spacings.

Rothmayer, A. P.; Smith, F. T.

1985-01-01

271

Modeling of Switching and Hysteresis in Molecular Transport

NASA Technical Reports Server (NTRS)

The conventional way of modeling current transport in two and three terminal molecular devices could be inadequate for certain cases involving switching and hysteresis. Here we present an alternate approach. Contrary to the regular way where applied bias directly modulates the conducting energy levels of the molecule, our method introduces a nonlinear potential energy surface varying with the applied bias as a control parameter. A time-dynamics is also introduced properly accounting for switching and hysteresis behavior. Although the model is phenomenological at this stage, we believe any detailed model would contain similar descriptions at its core.

Samanta, Manoj P.; Partridge, Harry (Technical Monitor)

2002-01-01

272

Dielectric Hysteresis Loop in Alicyclic and Aromatic Polyamides

NASA Astrophysics Data System (ADS)

The relationship between electric displacement D and electric field E was studied for alicyclic polyamides of 1,3-bis(aminomethyl)cyclohexane and adipic, pimelic and sebacic acids, an aromatic polyamide prepared from hexamethylenediamine (HMD) and isophthalic acid and a copolyamide of HMD with isophthalic and terephthalic acids. Quenched samples of these polyamides were poorly crystalline or amorphous and exhibited a D-E hysteresis loop with the remanent polarization of 26 to 38 mC·m-2. The remanent polarizations disappeared at the glass transition temperature of each sample. The origin of the D-E hysteresis loop is attributable to amide groups in amorphous regions.

Murata, Yukinobu; Tsunashima, Kenji; Koizumi, Naokazu

1994-03-01

273

NASA Astrophysics Data System (ADS)

This study presents a new theoretical model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for the accurate prediction of the spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, the connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity of void space to compute the hysteretic curves and to predict entrapped fluid phase saturations. Two functions, the probability of drainage and the probability of wetting, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, A.; Birkholzer, J. T.; Illangasekare, T. H.; Zhou, Q.

2013-12-01

274

The U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois, as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Lake Michigan Diversion Accounting is mandated by a U.S. Supreme Court decree in order to monitor, and limit, the State of Illinois’ annual diversion of Great Lakes water through the manmade CSSC. Every 5 years, a technical review committee consisting of practicing engineers and academics reviews USGS streamgaging practices in the CSSC near Lemont, Illinois. The sixth technical review committee expressed concern that the index-velocity rating—the method used to estimate mean cross-sectional velocity from a measured index velocity—may be subject to hysteresis at this site because of the unique, unsteady hydraulics of the canal. Hysteresis in index-velocity ratings can occur at sites where the flow distribution in the channel varies significantly between the rising and falling limbs of the hydrograph for the same discharge. Presently, hysteresis in index-velocity ratings has been documented only in tidally affected sites. This report investigates whether hysteresis can occur at this nontidal site, and the conditions under which it is likely to occur, by using both a theoretical approach and a three-dimensional hydrodynamic model. The theoretical analysis investigated the conditions required for hysteresis in the index-velocity rating, and the modeling analysis focused on the effect of the timing of the inflows from the CSSC and the Cal-Sag Channel on the potential for hysteresis and whether highly resolved simulations of actual high-flow events show any evidence of hysteresis. Based on both a theoretical analysis using observed historical data and an analysis using a three-dimensional hydrodynamic model, there is no conclusive evidence for the existence of hysteresis in the index-velocity rating at the USGS streamgage on the CSSC near Lemont, Illinois. Although the theoretical analysis indicated the possibility of hysteresis at this site, the hydrodynamic conditions required to generate hysteresis are not present at this site based on historical data. Ongoing streamgaging practices at this site will use the information in this report and include periodic assessment of the index-velocity rating for any signs of hysteresis that might result from future changes to the operation of this manmade canal.

Jackson, P. Ryan; Sinha, Sumit; Dutta, Som; Johnson, Kevin K.; Duncker, James J.; Garcia, Marcelo H.

2013-01-01

275

NASA Astrophysics Data System (ADS)

Hysteresis in the current-voltage characteristics is one of the major obstacles to the implementation of organic thin-film transistors in large-area integrated circuits. The hysteresis has been correlated either extrinsically to various charge-trapping/transfer mechanisms arising from gate dielectrics or surrounding ambience or intrinsically to the polaron-bipolaron reaction in low-mobility conjugated polymer thin-film transistors. However, a comprehensive understanding essential for developing viable solutions to eliminate hysteresis is yet to be established. By embedding carbon nanotubes in the polymer-based conduction channel of various lengths, here we show that the bipolaron formation/recombination combined with the H2O/O2 electrochemical reaction is responsible for the hysteresis in organic thin-film transistors. The bipolaron-induced hysteresis is a thermally activated process with an apparent activation energy of 0.29?eV for the bipolaron dissociation. This finding leads to a hysteresis model that is generally valid for thin-film transistors with both band transport and hopping conduction in semiconducting thin films.

Qu, Minni; Li, Hui; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

2014-01-01

276

An experimental investigation of the hysteresis during the E (capacitive coupling) and H mode (inductive coupling) transitions at various matching situation in argon inductively coupled plasma is reported. At high pressure, the results show two hysteresis loops involved the plasma density, applied power, and forward power, as well as the electrical parameters in the discharge circuit, when the series capacitance is cycled. The measured electron density versus applied power shows that the hysteresis loop shrinks with the decrease of the matching capacitance, and the same trend is discovered on the input current, voltage, and phase angle. In addition, for the case of small capacitance, the current (or voltage) jumps to a low value when the discharge passes through the E to H mode transition regime. Contrarily, for the case of large capacitance, the current jumps to a high value while the voltage is almost constant. The evolution characteristics of the plasma and circuit parameters observed imply that the nonlinear behavior of the matching situation may be one of the determined factors for hysteresis.

Gao Fei; Zhao Shuxia; Li Xiaosong; Wang Younian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2010-10-15

277

Hysteresis effects in the inverse magnetocaloric effect in martensitic Ni-Mn-In and Ni-Mn-Sn

NASA Astrophysics Data System (ADS)

The presence of a large inverse magnetocaloric effect around the martensitic transformation in Ni-Mn-Sn and Ni-Mn-In alloys is expected to lead to substantial cooling on applying a magnetic field. However, the occurrence of hysteresis around the transition causes limitations on adiabatic temperature-changes. We study the adiabatic temperature-change in both systems in relation to the hysteresis effects. Ni-Mn-In, having a relatively narrower hysteresis and a greater shift of the characteristic transition temperatures with applied field with respect to Ni-Mn-Sn, shows reversibility in the adiabatic-temperature change related to the inverse magnetocaloric effect when the state of the system is cycled within a minor transitional hysteresis loop. Ni-Mn-Sn does not show reversibility in the inverse magnetocaloric effect under cycling-fields up to 5 T. The reversibility in the adiabatic temperature-change is directly related to the reversibility in the relative amount of austenite and martensite in the sample when the field is cycled.

Titov, I.; Acet, M.; Farle, M.; González-Alonso, D.; Mañosa, L.; Planes, A.; Krenke, T.

2012-10-01

278

A dead-beat adaptive hysteresis current control

This paper proposes a new digital algorithm for the implementation of the fixed-frequency adaptive hysteresis current control for voltage-source inverters. The key features of the new algorithm are the minimization of the analog external circuitry, the capability to automatically compensate for the inverter deadtime effects without appreciable delay and a tight synchronization of the inverter voltage pulses with an external

Simone Buso; Sandro Fasolo; Luigi Malesani; Paolo Mattavelli

2000-01-01

279

Hysteresis in a simple model of currency substitution

A cash-in-advance model in which the cost of buying goods with a foreign currency is decreasing in the economy's accumulated experience in transacting in the foreign currency is shown to display hysteresis in money velocity; that is, a temporary increase in expected inflation can cause a permanent increase in velocity. In addition, the model implies that the domestic currency does

Martîn Uribe

1997-01-01

280

Elastic guides reduce hysteresis effect in Belleville spring package

NASA Technical Reports Server (NTRS)

Peripheral support guides that elastically flex with the slight breathing on radial displacement during actuation can greatly reduce the hysteresis present in a Belleville spring package. This technique provides a control device that enhances the precision of pressure regulating valves, pressure switches, and vacuum actuators.

Mc Glashan, W. F., Jr.; Toth, L. R.

1967-01-01

281

Periodic solutions of a forced system with hysteresis.

NASA Technical Reports Server (NTRS)

Hysteresis damping arising in an oscillatory system due to the phenomenon of slip damping analyzed by Goodman and Klumpp (1956) is considered. An idealized physical model is proposed, and the existence of certain periodic motions is investigated in a system with small forcing which are near the largest periodic motion in a corresponding unforced system. Periodic solutions of the forced system are obtained.-

Drew, J. H.

1972-01-01

282

Fourier analysis of digital hysteresis data: rock magnetic applications

The approach to saturation of a ferromagnetic material can be characterized in terms of the frequency content of its hysteresis loop. This is done by `unfolding' the loop into a pseudo-waveform, which is then analyzed using standard Fourier methods. In experiments on samples with discrete grain sizes of magnetite, the decay of Fourier component amplitude as a function of harmonic

Mike Jackson; Horst-Ulrich Worm; Subir K. Banerjee

1990-01-01

283

Probabilistic counter updates for predictor hysteresis and stratification

Hardware counters are a fundamental building block of modern high-performance processors. This paper ex- plores two applications of probabilistic counter updates, in which the output of a pseudo-random number generator de- cides whether to perform a counter increment or decrement. First, we discuss a probabilistic implementation of counter hysteresis, whereby previously proposed branch confidence and criticality predictors can be reduced

Nicholas Riley; Craig B. Zilles

2006-01-01

284

Dynamic Contact Angles and Hysteresis under Electrowetting-on-Dielectric

By designing and implementing a new experimental method, we have measured the dynamic advancing and receding contact angles and the resulting hysteresis of droplets under electrowetting-on-dielectric (EWOD). Measurements were obtained over wide ranges of applied EWOD voltages, or electrowetting numbers (0 ? Ew ? 0.9), and droplet sliding speeds, or capillary numbers (1.4×10-5 ? Ca ? 6.9×10-3). If Ew or Ca is low, dynamic contact angle hysteresis is not affected much by the EWOD voltage or the sliding speed, i.e., the hysteresis increases by less than 50% with a two order-of-magnitude increase in sliding speed when Ca < 10-3. If both Ew and Ca are high, however, the hysteresis increases with either the EWOD voltage or the sliding speed. Stick-slip oscillations were observed at Ew>0.4. Data are interpreted with simplified hydrodynamic (Cox-Voinov) and molecular-kinetic theory (MKT) models; the Cox-Voinov model captures the trend of the data, but yields unreasonable fitting parameters. MKT fitting parameters associated with the advancing contact line are reasonable, but a lack of symmetry indicates that a more intricate model is required.

Nelson, Wyatt C.; Sen, Prosenjit; Kim, Chang-Jin "CJ"

2011-01-01

285

Differential hysteresis modeling of a shape memory alloy wire actuator

In this paper, we develop a complete mathematical model of a shape memory alloy (SMA) wire actuated by an electric current and a bias spring. The operation of the SMA actuator involves different physical phenomena, such as heat transfer, phase transformation with temperature hysteresis, stress-strain variations and electrical resistance variation accompanying the phase transformation. We model each of these phenomena

Sushant M. Dutta; Fathi H. Ghorbel

2005-01-01

286

An Accurate Hysteresis Model for Ferroresonance Analysis of a Transformer

This paper introduces an accurate transformer core model, using the Preisach theory, to represent the core magnetization characteristic. This modeling approach provides the required precision to match major and minor hysteresis loops of the model with those of the actual transformer core material. Using the proposed model, the ferroresonance phenomenon of a voltage transformer (VT) is simulated and compared to

Afshin Rezaei-Zare; Reza Iravani; Majid Sanaye-Pasand; Hossein Mohseni; Shahrokh Farhangi

2008-01-01

287

Hysteresis in a swirling jet as a model tornado

A swirling jet, emerging normal to a plane, serves as a model of a tornado and is characterized by its flow force and outer circulation. This model is examined here using the full Navier-Stokes equations. Three branches of solutions are found which form a hysteresis loop and a cusp catastrophe that means jump transitions between flow regimes. One of the

V. Shtern; F. Hussain

1993-01-01

288

Iterative feedforward compensation of hysteresis in piezo positioners

In this article, we prove convergence of an iterative control algorithm to find an input that achieves precise positioning in hysteretic systems. In the analysis, the Preisach hysteresis model is used to characterize the nonlinear behavior of the piezo positioner. We quantify the number of iterations required to achieve a prescribed precision. The method is applied to an experimental piezo

Kam K. Leang; S. Devasia

2003-01-01

289

Novel Hysteresis Current Controller for Active Power Filter

The switching losses of Active Power Filter (APF) is one of the important factors that influence the performance-price ratio of APF. In this paper, a novel method is suggested. Under this new method, each phase output reference current of APF is compared to adjust hysteresis of each phase, so that the switching number of the phase that has greater switching

Zeng Jiang; Liu Yan; Ouyang Sen; Zhen Zaitian

2010-01-01

290

Hysteresis heating based induction bonding of composite materials

The viability of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composites is well established in this work. The unique ability to offer localized heating, geometric flexibility, and self-controlled temperature is the major advantage of this technique. Hysteresis heating is tailored through careful design of the microstructure of nickel particulate polymer films (Ni\\/PSU). An excellent

Witchuda Suwanwatana

2004-01-01

291

Magnetic Hysteresis Damping of Satellite Attitude Motion, Volume I.

National Technical Information Service (NTIS)

The attitude dynamics of a gravity-gradient oriented satellite, which employs soft nickel-iron rods as magnetic hysteresis dampers, is simulated by a digital computer program. A subroutine was generated to compute the flux induced in the rods for an arbit...

1964-01-01

292

Tracking Control of Piezoelectric Actuators by Feedforward Hysteresis Compensation

Due to the inherent hysteresis nonlinearity, the piezoelectric actuator always causes positioning error in the open-loop operation and instability in the closed-loop operation. In order to improve the positioning accuracy and response speed, a control method for piezoelectric actuator based on a PID feedback controller with a feedforward compensation is proposed. The feedforward controller based on a new mathematical model

Changhai Ru; Bohui Pang; Kejun Wang; Xiufen Ye

2006-01-01

293

Investigation of the Temperature Hysteresis Phenomenon of a Loop Heat Pipe.

National Technical Information Service (NTIS)

The temperature hysteresis phenomenon of a Loop Heat Pipe (LHP) was experimentally investigated. The temperature hysteresis was identified by the fact that the operating temperature depends upon not only the imposed power but also the previous history of ...

T. Kaya J. Ku T. Hoang M. K. Cheung

1999-01-01

294

The formulations for parametric curves and surfaces that are based on control points are revised to use control lines and control planes instead. Curves defined by control lines are called control- line curves or plus curves, and surfaces defined by control planes are called control-plane surfaces or plus surfaces; plus implies that in addition to the control points, tangents at

A. Ardeshir Goshtasby

2005-01-01

295

Magnetic hysteresis dynamics of thin Co films on Cu(001)

NASA Astrophysics Data System (ADS)

Hysteresis properties of ultrathin (2-4 monolayers) epitaxial Co films grown on Cu(001) surfaces are studied as a function of film thickness, temperature and the strength (H0), in-plane direction, and frequency (?) of applied sinusoidal magnetic field. Scaling of the hysteresis loop area (power loss) of the form A=A0+H?0???(H,?) where ? is a scaling function is explored. All films exhibit a threshold field (Ht) where switching between equivalent magnetized states is initiated. Hysteresis loop areas measured over five decades in frequency exhibit very weak power-law dependence (?~0.02). No evidence of a dynamic phase transition is observed and no indication of a low-frequency (?0~102 Hz) characteristic resonance is apparent over the drive frequency range covered. The observed weak power-law scaling does not support results of prior experiments that have been interpreted as corroborating the mean-field Ising model (?=?=23) and continuum spin models of thin-film hysteresis energy-loss scaling. The measured frequency and applied field-dependent scaling of the dynamic coercive force (H*c) also appears to be inconsistent with recent phenomenological models of hysteresis behavior based on domain-wall motion that predict that H*c scales as ln H?. The results of this study of Co on Cu(001) and a corresponding study of Fe on W(110) suggest that the dynamics of magnetization reversal in real ultrathin film systems do not exhibit universal behavior in the low-field low-frequency limit. Recent theoretical results based on a more realistic model that accounts for thermal noise and spatial fluctuations in the dynamics yield logarithmic scaling at low ? and effective exponents ? that are compatible with the experiments. A simple physical picture of low drive-frequency energy-loss scaling is described that accounts for the experimental observations.

Suen, Jih-Shin; Lee, M. H.; Teeter, G.; Erskine, J. L.

1999-02-01

296

Rotating cylindrical magnetrons are used intensively on industrial scale. A rotating cylindrical magnetron on laboratory scale makes it possible to study this deposition technique in detail and under well controlled conditions. Therefore, a small scale rotating cylindrical magnetron was designed and used to study the influence of the rotation speed on the hysteresis behavior during reactive magnetron sputtering of aluminum in Ar/O{sub 2} in dc mode. This study reveals that the hysteresis shifts towards lower oxygen flows when the rotation speed of the target is increased, i.e., target poisoning occurs more readily when the rotation speed is increased. The shift is more pronounced for the lower branch of the hysteresis loop than for the upper branch of the hysteresis. This behavior can be understood qualitatively. The results also show that the oxidation mechanism inside the race track is different from the oxidation mechanism outside the race track. Indeed, outside the race track the oxidation mechanism is only defined by chemisorption while inside the race track reactive ion implantation will also influence the oxidation mechanism.

Depla, D.; Haemers, J.; Buyle, G.; Gryse, R. de [Department of Solid State Sciences, Ghent University, Krijgslaan 281 (S1), B-9000 Ghent (Belgium)

2006-07-15

297

Major hysteresis loop modeling of two-dimensional arrays of single domain particles

We have studied the effect of magnetostatic interactions on the overall shape of hysteresis loops for arrays of single domain particles. A computational model was used to calculate major hysteresis loops of arrays of particles with an easy axis along the applied field. The shear of the hysteresis loop, and consequent loss of squareness, is found to increase both with

M. Hwang; M. Farhoud; Y. Hao; M. Walsh; T. A. Savas; Henry I. Smith; C. A. Ross

2000-01-01

298

Numerical characterization of dynamic hysteresis loops and losses in soft magnetic materials

This paper deals with the characterization of dynamic loops shapes and losses in soft magnetic materials. An experimental and theoretical analysis has been done in order to describe static and dynamic hysteresis on soft ferrite cores. A parallelogram-loop-based hysteresis modeling is described and discussed. The possibility of the model to include vector hysteresis and the related properties are then discussed,

E. Cardeffi; Romano Giannetti; Bernardo Tellini

2005-01-01

299

Reduction of major and minor hysteresis loops in a piezoelectric actuator

This paper addresses the compensation of major and minor hysteresis loops using an operator termed a phaser, which shifts the phase of a periodic signal by an amount ?. For periodic inputs, hysteresis can be approximated by a phaser with a negative phase shift opening the possibility of cascade compensation. Since in actual hysteresis the phase shift varies according to

Juan Manuel Cruz-hernández; Vincent Hayward

1998-01-01

300

Adaptive wavelet neural network control with hysteresis estimation for piezo-positioning mechanism

An adaptive wavelet neural network (AWNN) control with hysteresis estimation is proposed in this study to improve the control performance of a piezo-positioning mechanism, which is always severely deteriorated due to hysteresis effect. First, the control system configuration of the piezo-positioning mechanism is introduced. Then, a new hysteretic model by integrating a modified hysteresis friction force function is proposed to

Faa-jeng Lin; Hsin-jang Shieh; Po-kai Huang

2006-01-01

301

This paper proposes a generalized hysteresis current controlled three level voltage source inverter (VSI) based single phase shunt active power filter (SAPF). The three level inverter topologies considered in this paper are H-bridge and diode clamped inverters. A generalized hysteresis current control with multiband hysteresis modulation has been used to control the voltage source inverters in the shunt active power

Shweta Gautam; Rajesh Gupta

2010-01-01

302

Identification and simulation of a circuit-based model of magnetic hysteresis

Purpose – The scope of the work is to provide an identification procedure for an hysteresis model based on nonlinear circuit cells. Design\\/methodology\\/approach – An identification procedure for an hysteresis model based on nonlinear circuit cells is presented. The response of elementary cell is equal to a generalized play operator. The procedure allows the identification of the limit symmetric hysteresis

G. Gruosso; M. Repetto

2005-01-01

303

Points on Computable Curves of Computable Lengths

NASA Astrophysics Data System (ADS)

A computable plane curve is defined as the image of a computable real function from a closed interval to the real plane. As it is showed by Ko [7] that the length of a computable curve is not necessarily computable, even if the length is finite. Therefore, the set of the computable curves of computable lengths is different from the set of the computable curves of finite lengths. In this paper we show further that the points covered by these two sets of curves are different as well. More precisely, we construct a computable curve K of a finite length and a point z on the curve K such that the point z does not belong to any computable curve of computable length. This gives also a positive answer to an open question of Gu, Lutz and Mayordomo in [4].

Rettinger, Robert; Zheng, Xizhong

304

NASA Astrophysics Data System (ADS)

Non-Abelian gauge theory in curved space is analysed from two standpoints. In the first half various exact classical solutions are presented which solve matter field equations and the Einstein equations simultaneously. Their implications to the very early univere are discussed. In the second half the problem of dynamical mass generation by finite curvature is investigated to show the importance of quantum effects to phase transitions in curved space.

Hosotani, Y.

305

Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.

The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere-asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles. PMID:23925242

Abe-Ouchi, Ayako; Saito, Fuyuki; Kawamura, Kenji; Raymo, Maureen E; Okuno, Jun'ichi; Takahashi, Kunio; Blatter, Heinz

2013-08-01

306

The temperature dependence on the hysteresis of a-Si:H TFT has been investigated. We have also proposed and fabricated a new a-Si:H TFT pixel driving scheme, which can eliminate OLED current error caused by the hysteresis of a-Si:H TFT. At an elevated temperature from 25oC to 60oC, the VTH variation of a- Si:H TFT caused by hysteresis was decreased from 0.41V

Sang-Geun Park; Jae-Hoon Lee; Won-Kyu Lee; Min-Koo Han

307

Vortices and hysteresis in a rotating Bose-Einstein condensate with anharmonic confinement

We examine an effectively repulsive Bose-Einstein condensate of atoms that rotates in a quadratic-plus-quartic trapping potential. We investigate the phase diagram of the system as a function of the angular frequency of rotation and of the coupling constant, demonstrating that there are phase transitions between multiply and singly quantized vortex states. We also show that states of different circulation can be metastable and, as a result, the gas can exhibit hysteresis as the angular frequency of rotation of the trap is varied. The simplicity of the picture that emerges for small coupling strengths suggests that this system may be attractive for studies of phase transitions.

Jackson, A.D. [Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen O (Denmark); Kavoulakis, G.M. [Mathematical Physics, Lund Institute of Technology, P.O. Box 118, S-22100 Lund (Sweden)

2004-08-01

308

Well-posedness for a class of biological diffusion models with hysteresis effect

NASA Astrophysics Data System (ADS)

This paper is concerned with a class of biological models which consist of nonlinear diffusion equations and a hysteresis operator describing the relationship between some variables of the equations. The existence of solutions to the analogous problem was ever considered by Aiki and Minchev (SIAM J Math Anal 36:2020-2032, 2005) under some assumptions including the global Lipschitz continuity of reaction terms. We show the existence of nonnegative solutions to the problem under consideration using the approximation method when the reaction terms are locally Lipschitz continuous. Moreover, we discuss the continuous dependence of solutions on initial data.

Zheng, Jiashan; Wang, Yifu

2014-05-01

309

Mesoscopic resistive switch: non-volatility, hysteresis and negative differential resistance

NASA Astrophysics Data System (ADS)

We show how a simple model nanoswitch can perform as a memory resistor. Its resistance is determined by electron tunneling through a nanoparticle diffusing around one or more potential minima located between the electrodes in the presence of Joule's heat dissipation. In the case of a single potential minimum, we observe hysteresis of the resistance at finite applied currents and negative differential resistance. For two (or more) minima the switching mechanism is non-volatile, meaning that the memristor can switch to a resistive state of choice and stay there. Moreover, the noise spectra of the switch exhibit 1/ f 2 ? 1/ f crossover, in agreement with recent experimental results.

Savel'ev, Sergey E.; Marchesoni, Fabio; Bratkovsky, Alexander M.

2013-12-01

310

NASA Astrophysics Data System (ADS)

The sensitivity and hysteresis effects of ion-sensitive field-effect transistor (ISFET) devices based on a-WO3, Ta2O5, and a-Si:H thin films have been investigated. The pH sensitivity is one of the important characteristic parameters of ISFET devices, and the response of an ISFET is mainly determined by the type of the sensing membrane; therefore the sensing material plays a significant role. Furthermore, hysteresis leads to inaccuracy and instability of ISFET measuring devices. In this investigation the pH sensitivities of different sensing-gate ISFET devices were measured in different buffer solutions by current-voltage (I-V) measurement, and the hysteresis curves were measured by exposing the device to several cycles of pH values over different loop times. According to the experimental results, a-WO3 and a- Si:H are useful in acidic buffer solutions (pH 1 to 7), and Ta2O5 at pH 1 to 12. The pH sensitivities are all larger than 50 mV/pH, and it was found that the key parameter in determining the hysteresis width is the loop time.

Chiang, Jung Lung; Chou, Jung Chuan; Chen, Ying-Chung

2002-08-01

311

Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions

NASA Astrophysics Data System (ADS)

Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC˜T) for single stormflow events was observed and quantified for a dataset of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009-2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine silt and smaller sizes (finer than 16 µm). This study shows that small changes in the often assumed stability of the PSD are significant to SSC˜T relations. Changes of only 5 µm in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC˜T rating that can increase error and produce bias. Observed SSC˜T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity limited for sand-sized sediment in the channel and supply limited for fine silt and smaller sediment from the hillslope.

Landers, Mark N.; Sturm, Terry W.

2013-09-01

312

Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions

Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC~T) for single stormflow events was observed and quantified for a data set of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009–2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine-silt and smaller sizes (finer than 16 microns). This study shows that small changes in the often assumed stability of the PSD are significant to SSC~T relations. Changes of only 5 microns in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC~T rating that can increase error and produce bias. Observed SSC~T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity-limited for sand-sized sediment in the channel and supply-limited for fine silt and smaller sediment from the hillslope.

Landers, Mark N.; Sturm, Terry W.

2013-01-01

313

Hysteresis effects in the formation of a neutralizing beam plasma at low ion energy

NASA Astrophysics Data System (ADS)

In this paper, the PEGASES II thruster prototype is used as an ion source generating low-energy (<300\\ \\text{eV}) positive Ar ion beam, extracted without an external neutralizer. The ions are extracted and accelerated from the source using a two-grid system. The extracted positive ion beam current is measured on a large beam target that can be translated along the acceleration axis. The ion beam current shows a stepwise transition from a low-current to a high-current extraction regime with hysteresis. The hysteresis region depends strongly upon the beam target position. Langmuir probe measurements in the plume show high plasma potentials and low plasma densities in the low-current mode, while the plasma potential drops and the density increases in the high-current mode. The ion energy distribution functions of the beam are measured for different regimes of ion extraction. The ion beam extracted in the high-current mode is indicated by the presence of an additional low-energy peak corresponding to ions from an ion-beam plasma created in the downstream chamber, as well as 10-20 times higher intensity of the primary ion beam peak. The hysteresis behavior is explained by the formation of a downstream neutralizing beam plasma, that depends on the target position and pressure in agreement with a Paschen-like breakdown by secondary electrons. The obtained results are of high relevance for further development of the PEGASES thruster, as well as for improving existing neutralizer-free concepts of the broad-beam ion sources.

Rafalskyi, Dmytro; Aanesland, Ane

2013-11-01

314

Hysteresis and Kinetic Effects During Liquid-Solid Transitions

We address the fundamental issue of phase transition kinetics in dynamically compressed materials. Focusing on solid bismuth (Bi) as a prototype material, we used a variety of time-resolved experiments including electrical conductivity and velocimetry to study the phase transition kinetics of the solid-solid phase transitions. Simple single shock experiments performed on several low-lying high pressure phases of Bi, revealed surprisingly complex behavior and slow dynamics. Strong hysteresis effects were observed in the transition behavior in experiments where the compressed Bi was allowed to release back across a phase line. These experiments represent the first reported simultaneous use of resistivity and velocimetry in a shock compression experiment, and the first observation of hysteresis effects occurring during dynamic compression and release.

Streitz, F H; Chau, R

2009-02-17

315

Hysteresis in the Underdamped Driven Frenkel-Kontorova Model

We study a commensurate chain of atoms subject to a periodic substrate potential, damping, and a thermal bath, and driven by an external dc force. In the underdamped case the average system velocity as a function of adiabatically varying force exhibits hysteresis at nonzero temperatures. The hysteresis exists due to the instability of the driven motion of kinks at high velocities. In the force-decreasing process, the system passes through two regimes: the {open_quotes}cavity-mode{close_quotes} regime (a standing wave superimposed on the state of running atoms) and the {open_quotes}traffic-jam{close_quotes} regime, where the mobility is due to kink-antikink pairs, the kinks being bunched into compact groups. {copyright} {ital 1997} {ital The American Physical Society}

Braun, O.M.; Bishop, A.R.; Roeder, J. [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Braun, O.M. [Institute of Physics, Ukrainian Academy of Sciences, 46 Science Avenue, UA-252022 Kiev (Ukraine)] [Institute of Physics, Ukrainian Academy of Sciences, 46 Science Avenue, UA-252022 Kiev (Ukraine)

1997-11-01

316

Simple Model Analysis of Hysteresis Phenomenon of Gas Discharge Plasma

NASA Astrophysics Data System (ADS)

The hysteresis and multiple-steady states of gas discharge plasma are analyzed by a simple model of chemical-reaction system. In our analysis the emergence of multiple-steady states is explained by using a fact that a function describing the energy balance has three different real roots. The condition that the function has three roots depends on the ratio of the bulk energy increase to the surface energy loss of plasma. The criterion of taking place of the jump between two steady states is examined in a similar manner to order-disorder transition. The critical parameter contains the non-thermodynamic variables such as conductivity and surface quantities. Stabilities of three obtained solutions are discussed by using linear analysis of differential equations and we find that a root represents a saddle point and other two roots represent stable points. The first step to explain the hysteresis phenomenon in Ar gas discharge plasma is found.

Matsunaga, Yasushi; Kato, Tomokazu

1997-01-01

317

Method of thermal strain hysteresis reduction in metal matrix composites

NASA Technical Reports Server (NTRS)

A method is disclosed for treating graphite reinforced metal matrix composites so as to eliminate thermal strain hysteresis and impart dimensional stability through a large thermal cycle. The method is applied to the composite post fabrication and is effective on metal matrix materials using graphite fibers manufactured by both the hot roll bonding and diffusion bonding techniques. The method consists of first heat treating the material in a solution anneal oven followed by a water quench and then subjecting the material to a cryogenic treatment in a cryogenic oven. This heat treatment and cryogenic stress reflief is effective in imparting a dimensional stability and reduced thermal strain hysteresis in the material over a -250.degree. F. to +250.degree. F. thermal cycle.

Dries, Gregory A. (Inventor); Tompkins, Stephen S. (Inventor)

1987-01-01

318

Sediment Hysteresis Patterns In Singapore Urban Residential Lined Channels

A study involving Jurong West (JW)(68.7 ha) and Ang Mo Kio (AMK)(34.9 ha) residential catchments in Singapore was conducted to analyse temporal total suspended sediment concentrations (TSS) in lined drainage channels during rain events. 53 and 25 storm events were sampled respectively for JW and AMK. 3 types of hysteresis patterns namely, clockwise, eight shaped and random shaped were identified.

W. Lee

2006-01-01

319

Degradation and capacitance: voltage hysteresis in CdTe devices

NASA Astrophysics Data System (ADS)

CdS/CdTe photovoltaic solar cells were made on two different transparent conducting oxide (TCO) structures in order to identify differences in fabrication, performance, and reliability. In one set of cells, chemical vapor deposition (CVD) was used to deposit a bi-layer TCO on Corning 7059 borosilicate glass consisting of a F-doped, conductive tin-oxide (cSnO2) layer capped by an insulating (undoped), buffer (iSnO2) layer. In the other set, a more advanced bi-layer structure consisting of sputtered cadmium stannate (Cd2SnO4; CTO) as the conducting layer and zinc stannate (Zn2SnO4; ZTO) as the buffer layer was used. CTO/ZTO substrates yielded higher performance devices however performance uniformity was worse due to possible strain effects associated with TCO layer fabrication. Cells using the SnO2-based structure were only slightly lower in performance, but exhibited considerably greater performance uniformity. When subjected to accelerated lifetime testing (ALT) at 85 - 100 °C under 1-sun illumination and open-circuit bias, more degradation was observed in CdTe cells deposited on the CTO/ZTO substrates. Considerable C-V hysteresis, defined as the depletion width difference between reverse and forward direction scans, was observed in all Cu-doped CdTe cells. These same effects can also be observed in thin-film modules. Hysteresis was observed to increase with increasing stress and degradation. The mechanism for hysteresis is discussed in terms of both an ionic-drift model and one involving majority carrier emission in the space-charge region (SCR). The increased generation of hysteresis observed in CdTe cells deposited on CTO/ZTO substrates suggests potential decomposition of these latter oxides when subjected to stress testing.

Albin, D. S.; Dhere, R. G.; Glynn, S. C.; Del Cueto, J. A.; Metzger, W. K.

2009-08-01

320

A new paradigm for modelling hysteresis in macroeconomic flows

NASA Astrophysics Data System (ADS)

Macroeconomic processes are often conceptualised as “flows”, and analogies are drawn with physical flow processes. Most economic processes, however, carry inherent irreversibility, a fact which these analogies neglect. A better metaphor for economic flows is suggested, involving flows through porous media. This new conceptual framework incorporates important features such as irreversibility and heterostasis through the use of hysteresis. A simple example model is derived, which may be used to derive qualitative results.

Cross, R.; McNamara, H.; Pokrovskii, A.; Rachinskii, D.

2008-02-01

321

An analysis of metal fatigue based on hysteresis energy

Halford's plastic-energy concept for lowcycle fatigue is extended to the medium- and high-cycle ranges. The resulting equations are compared with 74 sets of data in the medium- and high-cycle ranges. The difference in stress between theory and experimental data is less than ±5 percent.The plastic-hysteresis-energy analysis for fatigue is shown to be consistent with the octahedral shear-stress theory. In addition,

C. S. Chang; W. T. Pimbley; H. D. Conway

1968-01-01

322

Hysteresis of Two Inequivalent Planar Magnets with Anisotropy

We study the hysteresis loops for two inequivalent planar magnets with equal magnetic moments and perpendicular anisotropy, which interact via the dipole-dipole interaction. We emphasize locating distinct zero net-magnetization states in zero applied field. We consider a wide range of perpendicular anisotropy constants K1 and K_2and dipole interaction strength g. For a wide range of parameter space (K_2\\/K_1, g\\/K_1) and

Benjamin T. King; M. Amin Kayali; Wayne M. Saslow

2004-01-01

323

Vector hysteresis measurements via a single disk tester

NASA Astrophysics Data System (ADS)

In this paper we present a single disk tester (SDT) developed for vector hysteresis measurements of magnetic steels. The measurement system deals with a stator of a 3-phase induction motor and some suitable magnetic field and magnetic induction probes. Numerical calculations based to a FEM approach in time domain and experimental tests are shown in order to describe both accuracy and efficiency of this measurement system.

Cardelli, E.; Faba, A.

2006-02-01

324

Hysteresis properties of titanomagnetites: Grain-size and compositional dependence

Sized fractions of x = 0.6, 0.4, 0.2 and 0.0 titanomagnetites were studied with a vibration magnetometer. In the course particles (d > 150 mum), no compositional dependence of hysteresis parameters was found. HC was less than 50 Oe, HR\\/HC > 4 and JR\\/JS < 10-2, reflecting multi-domain behaviour. In contrast, fine particles (d ⋍ 0.1 mum) revealed systematic grain-size

R. Day; M. Fuller; V. A. Schmidt

1977-01-01

325

Applications of hysteresis switching in parameter adaptive control

The hysteresis switching algorithm of R.H. Middleton et al. (ibid., vol.33, no.1, p.50-8, Jan. 1988) is reexamined in a broader context. To demonstrate its utility, the algorithm is applied to various families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the direct control type results in a model reference adaptive controller capable of stabilizing,

A. Stephen Morse; David Q. Mayne; Graham C. Goodwin

1992-01-01

326

National Technical Information Service (NTIS)

A spot-mounted, variable, rate-controlled hydraulic manipulator was developed for the cable-controlled undersea research vehicles, CURV 2 and CURV 3. This manipulator incorporates a mechanical linkage arm which provides linear hand extension and eliminate...

R. Uhrich

1971-01-01

327

NASA Astrophysics Data System (ADS)

Like most smart materials, such as piezoelectric materials and shape memory alloys, ion-exchange polymer-metal composite (IPMC), which is a kind of electroactive polymer material, exhibits the properties of hysteresis and creep. In this paper we explain the hysteresis and creep properties of IPMC, analyze the hysteresis using a discrete Prandtl-lshlinskii model, obtain a creep model of IPMC through modifying the creep model of piezoelectric material and present an inverse model of the hysteresis. For hysteresis and creep properties of IPMC changing with time at different rates, we applied the LMS (least mean square) algorithm to identify the hysteresis parameters online. An offline identification algorithm was used to obtain the creep parameters. An adaptive inverse strategy of control for IPMC actuators was set up on the basis of a superposition model of nonlinear hysteresis and linear creep, and we obtained good simulation and experiment results.

Hao, Lina; Li, Zhi

2010-02-01

328

Wettability hysteresis and its implications for DNAPL source zone distribution.

Subsurface heterogeneity at sites contaminated with nonaqueous phase liquids (NAPLs) reduces the effectiveness of traditional remediation measures. One cause may be the increased proportion of NAPL that is hydraulically isolated due to capillary trapping in heterogeneously-wetted materials. This study examines the wettability of ten materials, ranging from minerals, such as calcite and dolomite, to carbonaceous materials, such shale and coal, in air and water, NAPL and air, and NAPL and water systems. The wettability differed depending on which phase the solid material was initially immersed in: the less crystalline solids, if initially contacted by water were water-wet, but if initially contacted by NAPL were NAPL-wet. This difference, termed here wettability hysteresis, was observed for a suite of halogenated NAPLs and was independent of equilibration time. The degree of wettability hysteresis was greatest in the NAPL and water systems, with the magnitude of the difference increasing with the carbonaceous materials. Since the degree of capillary trapping in subsurface materials is related to wettability, the phenomenon of wettability hysteresis suggests that system history is a factor that may increase the heterogeneity of NAPL source zones. PMID:18848369

Ryder, Jodi L; Demond, Avery H

2008-11-14

329

From principal curves to granular principal curves.

Principal curves arising as an essential construct in dimensionality reduction and data analysis have recently attracted much attention from theoretical as well as practical perspective. In many real-world situations, however, the efficiency of existing principal curves algorithms is often arguable, in particular when dealing with massive data owing to the associated high computational complexity. A certain drawback of these constructs stems from the fact that in several applications principal curves cannot fully capture some essential problem-oriented facets of the data dealing with width, aspect ratio, width change, etc. Information granulation is a powerful tool supporting processing and interpreting massive data. In this paper, invoking the underlying ideas of information granulation, we propose a granular principal curves approach, regarded as an extension of principal curves algorithms, to improve efficiency and achieve a sound accuracy-efficiency tradeoff. First, large amounts of numerical data are granulated into C intervals-information granules developed with the use of fuzzy C-means clustering and the two criteria of information granulation, which significantly reduce the amount of data to be processed at the later phase of the overall design. Granular principal curves are then constructed by determining the upper and the lower bounds of the interval data. Finally, we develop an objective function using the criteria of information confidence and specificity to evaluate the granular output formed by the principal curves. We also optimize the granular principal curves by adjusting the level of information granularity (the number of clusters), which is realized with the aid of the particle swarm optimization. A number of numeric studies completed for synthetic and real-world datasets provide a useful quantifiable insight into the effectiveness of the proposed algorithm. PMID:23996588

Zhang, Hongyun; Pedrycz, Witold; Miao, Duoqian; Wei, Zhihua

2014-06-01

330

An extraordinary origami curve

We study a special Teichmueller curve in the moduli space of curves of genus\\u000a3 that is intersected by infinitely many other Teichmueller curves. The Veech\\u000agroup of the underlying translation surface is SL_2(Z). All occurring\\u000aTeichmueller curves are induced by origamis, i.e. unramified coverings of the\\u000aonce punctured torus.

Frank Herrlich; Gabriela Schmithusen

2008-01-01

331

The objective is to investigate experimentally and theoretically the effects of neutron embrittlement and biaxial stress on magnetic properties in steels, using various magnetic measurement techniques. Interaction between experiment and modeling should suggest efficient magnetic measurement procedures for determining neutron embrittlement biaxial stress. This should ultimately assist in safety monitoring of nuclear power plants and of gas and oil pipelines. In the first six months of this first year study, magnetic measurements were made on steel surveillance specimens from the Indian Point 2 and D.C. Cook 2 reactors. The specimens previously had been characterized by Charpy tests after specified neutron fluences. Measurements now included: (1) hysteresis loop measurement of coercive force, permeability and remanence, (2) Barkhausen noise amplitude; and (3) higher order nonlinear harmonic analysis of a 1 Hz magnetic excitation. Very good correlation of magnetic parameters with fluence and embrittlement was found for specimens from the Indian Point 2 reactor. The D.C. Cook 2 specimens, however showed poor correlation. Possible contributing factors to this are: (1) metallurgical differences between D.C. Cook 2 and Indian Point 2 specimens; (2) statistical variations in embrittlement parameters for individual samples away from the stated men values; and (3) conversion of the D.C. Cook 2 reactor to a low leakage core configuration in the middle of the period of surveillance. Modeling using a magnetomechanical hysteresis model has begun. The modeling will first focus on why Barkhausen noise and nonlinear harmonic amplitudes appear to be better indicators of embrittlement than the hysteresis loop parameters.

Sablik, M.J.; Kwun, H.; Rollwitz, W.L.; Cadena, D.

1992-01-01

332

NASA Astrophysics Data System (ADS)

Magnetic properties are sensitive proxies to characterize FeNi metal phases in meteorites. We present a data set of magnetic hysteresis properties of 91 ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite that dominates the induced magnetism and tetrataenite (both in the cloudy zone as single-domain grains, and as larger multidomain grains in plessite and in the rim of zoned taenite) dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. The bulk metal contents derived from magnetic measurements are in agreement with those estimated previously from chemical analyses. We evidence a decreasing metal content with increasing petrologic type in ordinary chondrites, compatible with oxidation of metal during thermal metamorphism. Types 5 and 6 ordinary chondrites have higher tetrataenite content than type 4 chondrites. This is compatible with lower cooling rates in the 650-450 °C interval for higher petrographic types (consistent with an onion-shell model), but is more likely the result of the oxidation of ordinary chondrites with increasing metamorphism. In equilibrated chondrites, shock-related transient heating events above approximately 500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism and high cooling rates (e.g., following shock reheating or excavation after thermal metamorphism). Our data strengthen the view that the poor magnetic recording properties of multidomain kamacite and the secondary origin of tetrataenite make equilibrated ordinary chondrites challenging targets for paleomagnetic study.

Gattacceca, J.; Suavet, C.; Rochette, P.; Weiss, B. P.; Winklhofer, M.; Uehara, M.; Friedrich, Jon M.

2014-04-01

333

NASA Astrophysics Data System (ADS)

We show that simple axisymmetric Newtonian calculation suffices to consistently connect disk galaxy rotation curves to underlying mass distribution and vice versa, without need for any dark matter. To this end, we connect mass density profiles of five galaxies of varying sizes with observed galaxy rotation curves. The five galaxies are: NGC6822 (4.8 kpc), Large Magellanic Cloud (9 kpc), The Milky Way (17 kpc), NGC3198 (30 kpc) and UGC9133 (102.5 kpc). The mass and mass density profiles of these galaxies have been computed using the scientific computing s/w package MATLAB taking the already available velocity profiles of the galaxies as the input, and without considering any dark matter contribution. We have plotted these profiles after computing them according to three different theories of gravity (and dynamics): Newtonian, Modified Newtonian Dynamics (MOND) and Vacuum Modified Gravity. We also consider how the profile due to the Newtonian theory would modify if we use a cosmological constant = 5 × 10^{-56} cm^{-2}. Comparing these mass and mass density profiles, we try to form an idea regarding what could be a realistic theory of gravity and whether we need dark matter to explain the results.

Banhatti, Dilip G.; Datta, Rahul

334

A suite of user-friendly global climate models: Hysteresis experiments

NASA Astrophysics Data System (ADS)

A hierarchy of global spectral circulation models is introduced ranging from the shallow-water system via the primitive-equation dynamical core of the atmosphere to the Planet Simulator as a Global Climate Model (GCM) of Intermediate Complexity (MIC) which can be used to run climate and paleo-climate simulations for time scales up to ten thousand years or more in an acceptable real time. The priorities in development are set to speed, easy handling and portability with a modular structure suitable for problem-dependent configuration. Adaptions exist for the planetary atmospheres of Mars and of Saturn's moon Titan and are being extended. Common coupling interfaces enable the addition of ocean, ice, vegetation models and more. An interactive mode with a Model Starter and a Graphical User Interface (GUI) is available to select a configuration from the available model suite, to set its parameters and inspect atmospheric fields while changing the models' parameters on the fly. This is especially useful for teaching, debugging and tuning of parameterizations. An updated overview of the model suite's features is presented based on the Earth-like climate model Planet Simulator with mixed-layer ocean introducing static and memory hysteresis in terms of a parameter sweep of the solar constant and CO2 concentrations. The static hysteresis experiment demonstrates that the solar constant varying by 20% reveals warm and snowball Earth climate regimes depending on the history of the system. This hysteresis subjected to a thermodynamic analysis shows the following features: i) Both climate regimes are characterized by global mean surface temperature and entropy growing with increasing solar constant. ii) The climate system's efficiency decreases (increases) with increasing solar constant in present-day warm (snowball) climate conditions. iii) Climate transitions near bifurcation points are characterized by high efficiency associated with the system's large distance from the stable regime. Memory hysteresis evolves when changing the direct atmospheric radiative forcing which, associated with a well-mixed CO2 concentration, modifies the planetary thermodynamic state, and hence the surface temperature. The hysteresis effected by different CO2 change rates is analysed: i) The response is due to infrared cooling (for constant temperature lapse-rate) which, in turn, is related to the surface temperature through the Stefan-Boltzmann law in a ratio proportional to the new infrared opacity. Subsequent indirect effects, that are water-vapour-greenhouse and ice-albedo feedbacks, enhance the response. ii) Different rates of CO2 variation may lead to similar transient climates characterized by the same global mean surface temperature but different values of CO2 concentration. iii) Far from the bifurcation points, the model's climate depends on the history of the radiative forcing thus displaying a hysteresis cycle that is neither static nor dynamical, but is related to the memory response of the model determined by the mixed-layer depth of the ocean. Results are supported by a zero-dimensional energy balance model.

Fraedrich, K.

2012-05-01

335

A BH Curve Tracer for Magnetic-Recording Wire

The equipment described is able to show on the screen of an oscilloscope the cyclic hysteresis loop of a sample of magnetic-recording wire a little over one inch long and 0.004 inch in diameter. Results obtained with the equipment in studying recording wires are given. A discussion is included of the operation of the equipment, and of possible modifications.

T. H. Long; G. D. McMullen

1946-01-01

336

Clapeyron slope reversal in the melting curve of AuGa2 at 5.5 GPa.

We use x-ray diffraction in a resistively heated diamond anvil cell to extend the melting curve of AuGa2 beyond its minimum at 5.5 GPa and 720 K, and to constrain the high-temperature phase boundaries between cubic (fluorite structure), orthorhombic (cottunite structure) and monoclinic phases. We document a large change in Clapeyron slope that coincides with the transitions from cubic to lower symmetry phases, showing that a structural transition is the direct cause of the change in slope. In addition, moderate (~30 K) to large (90 K) hysteresis is detected between melting and freezing, from which we infer that at high pressures, AuGa2 crystals can remain in a metastable state at more than 5% above the thermodynamic melting temperature. PMID:24025237

Geballe, Z M; Raju, S V; Godwal, B K; Jeanloz, R

2013-10-16

337

NASA Astrophysics Data System (ADS)

A new driving scheme for an active-matrix organic light emitting diode (AMOLED) display was developed to prevent the picture quality degradation caused by the hysteresis characteristics of organic thin film transistors (OTFTs). In this driving scheme, the gate electrode voltage of a driving-OTFT is directly controlled through the storage capacitor so that the operating point for the driving-OTFT is on the same hysteresis curve for every pixel after signal data are stored in the storage capacitor. Although the number of OTFTs in each pixel for the AMOLED display is restricted because OTFT size should be large enough to drive organic light emitting diodes (OLEDs) due to their small carrier mobility, it can improve the picture quality for an OTFT-driven flexible OLED display with the basic two transistor-one capacitor circuitry.

Yamamoto, Toshihiro; Nakajima, Yoshiki; Takei, Tatsuya; Fujisaki, Yoshihide; Fukagawa, Hirohiko; Suzuki, Mitsunori; Motomura, Genichi; Sato, Hiroto; Tokito, Shizuo; Fujikake, Hideo

2011-02-01

338

Television Quiz Show Simulation

ERIC Educational Resources Information Center

This article explores the simulation of four television quiz shows for students in China studying English as a foreign language (EFL). It discusses the adaptation and implementation of television quiz shows and how the students reacted to them.

Hill, Jonnie Lynn

2007-01-01

339

On the benefits of hysteresis effects for closed-loop separation control using plasma actuation

NASA Astrophysics Data System (ADS)

Flow separation control by a non-thermal plasma actuator is considered for a NACA 0015 airfoil at a chord Reynolds number of 1.9 × 105. Static hysteresis in the lift coefficient is demonstrated for increasing and then decreasing sinusoidal voltage amplitude supplying a typical single dielectric barrier discharge actuator at the leading edge of the model. In addition to these open-loop experiments, unsteady surface pressure signals are examined for transient processes involving forced reattachment and natural separation. The results show that strong pressure oscillations in the relatively slow separation process, compared to reattachment, precede the ultimate massive flow separation. To enhance the contrast between the parts of the signal related to the attached flow and those related to the incipient separation, RMS estimate of filtered values of Cp is used to define a flow separation predictor that is implemented in feedback control. Two simple controllers are proposed, one based on a predefined threshold of the unsteady Cp and another that utilizes the flow separation predictor to identify incipient separation. The latter effectively leverages the hysteresis in the post-stall regime to reduce the electrical power consumed by the actuator while maintaining continuously attached flow.

Benard, N.; Cattafesta, L. N.; Moreau, E.; Griffin, J.; Bonnet, J. P.

2011-08-01

340

Boosting the Area under the ROC Curve

We show that any weak ranker that can achieve an area under the ROC curve slightly better than 1\\/2 (which can be achieved by random guessing) can be effi- ciently boosted to achieve an area under the ROC curve arbitrarily close to 1. We further show that this boosting can be performed even in the presence of indepen- dent misclassification

Philip M. Long; Rocco A. Servedio

2007-01-01

341

Local Condensation Curve from Dropwise to Glacial Region on Large Vertical Surface

NASA Astrophysics Data System (ADS)

The existence of several regimes of condensation heat transfer is well known. Regimes are given academic names as dropwise, transition, film and glacial condensation along the condensation curve showing the relationship between heat flux and surface subcooling. In case of comparatively large vertical surface, the lower part on the gravitational direction is affected by condensate from the upper part, and will be covered by water stream like a rivulet. It has no longer an existence as dropwise condition, and it is absolutely impossible that heat transfer problems under constant temperature or constant heat flux take place. The reason is why as follows, heat transfer of film condensation is some orders of magnitude less than dropwise condensation, and various regimes exist together simultaneously. In the present paper we shall try to observe the coexisting appearance of regimes in steam condensation at atmospheric pressure and make researches in the local condensation curve from top to bottom on the same surface, that is divided into eight parts in the rear side. The main results are shown as follows (1) Enhancement of heat transfer by wiping of drops appears toward somewhat lower position from top. (2) Frazil ice is observed in the supercooled liquid film flowing down on glacial condensation. (3) The regime of glacial condensation describes a thermal hysteresis loop.

Haraguchi, Tadao; Shimada, Ryohachi; Takeyama, Toshiro

342

Research on elliptic curve cryptography

There are many drawbacks in current encryption algorithms in respect of security, real-time performance and so on, and researchers are presenting various algorithms. Among them, the elliptic curve cryptography (ECC) is evolving as an important cryptography, and shows a promise to be an alternative of RSA. Small size, high security and other features characterize ECC. Based on the theory of

Qizhi Qiu; Qianxing Xiong

2004-01-01

343

NASA Astrophysics Data System (ADS)

A digitization scheme of sub-microampere current using a commercial comparator with adjustable hysteresis and FPGA-based Wave Union TDC has been tested. The comparator plus a few passive components forms a current controlled oscillator and the input current is sent into the hysteresis control pin. The input current is converted into the transition times of the oscillations, which are digitized with a Wave Union TDC in FPGA and the variation of the transition times reflects the variation of the input current. Preliminary tests show that input charges < 25 fC can be measured at > 50 M samples/s without a preamplifier.

Wu, J.

2013-01-01

344

Ferroelectric superlattice heterostructures have recently been explored for potential applications in electronic devices. In this letter we employed the phase-field approach to simulate the domain structure and switching of a (BaTiO3)8/(SrTiO3)3 superlattice film constrained by a GdScO3 substrate. A constricted ferroelectric hysteresis loop was observed with a high saturation polarization but a small coercive field. The shape of the hysteresis loop is understood by analyzing the ferroelectric polarization distributions during switching. It is demonstrated that the constricted loop show a similar mechanism to the exchange coupling effect in magnetic multilayers.

Wu, Pingping; Ma, Xingqiao; Li, Yulan; Gopalan, Venkatraman; Chen , L.Q.

2012-03-01

345

Curve Family Index (Visual Dictionary of Special Plane Curves)

NSDL National Science Digital Library

A discussion of the many ways to classify curves, how they are named, a curve family tree, and interconnection between curves, with related Web sites about fractals and curves. Hosted by the Math Forum.

Lee, Xah

2007-12-20

346

Mathematical Curve Conjectures

NSDL National Science Digital Library

In this activity, a six-foot length of nylon rope is suspended at both ends to model a mathematical curve known as the hyperbolic cosine. In a write-pair-share activity, students are asked to make a conjecture concerning the nature of the curve and then embark on a guided discovery in which they attempt to determine a precise mathematical description of the curve using function notation.

Rutledge, James

347

Ionically-mediated electromechanical hysteresis in transition metal oxides

Electromechanical activity, remanent polarization states, and hysteresis loops in paraelectric TiO2 and SrTiO3 are observed. The coupling between the ionic dynamics and incipient ferroelectricity in these materials is analyzed using extended Ginsburg Landau Devonshire (GLD) theory. The possible origins of electromechanical coupling including ionic dynamics, surface-charge induced electrostriction, and ionically-induced ferroelectricity are identified. For the latter, the ionic contribution can change the sign of first order GLD expansion coefficient, rendering material effectively ferroelectric. These studies provide possible explanation for ferroelectric-like behavior in centrosymmetric transition metal oxides.

Kim, Yunseok [ORNL] [ORNL; Kumar, Amit [ORNL] [ORNL; Jesse, Stephen [ORNL] [ORNL; Kalinin, Sergei V [ORNL] [ORNL

2012-01-01

348

A study of hysteresis in the K ID -å relation

A photoelastic study of high speed crack propagation in Homalite 100 was conducted to measure hysteresis in the constitutive\\u000a relation forK\\u000a \\u000a ID\\u000a -. The fracture specimen was designed to obtain both crack acceleration and deceleration during a single crack extension.\\u000a Additional loads perpendicular to the crck-propagation path were applied at secondary locations to accentuate the magnitude\\u000a of acceleration-deceleration observed in

J. W. Dally; R. K. Agarwal; R. J. Sanford

1990-01-01

349

Effect of contact angle hysteresis on moving liquid film integrity

NASA Technical Reports Server (NTRS)

A study was made of the formation and breakdown of a water film moving over solid surfaces (teflon, lucite, stainless steel, and copper). The flow rate associated with film formation was found to be higher than the flow rate at which film breakdown occurred. The difference in the flow rates for film formation and film breakdown was attributed to contact angle hysteresis. Analysis and experiment, which are in good agreement, indicated that film formation and film breakdown are functions of the advancing and receding angles, respectively.

Simon, F. F.; Hsu, Y. Y.

1972-01-01

350

Effect of contact angle hysteresis on moving liquid film integrity.

NASA Technical Reports Server (NTRS)

A study was made of the formation and breakdown of a water film moving over solid surfaces (teflon, lucite, stainless steel, and copper). The flow rate associated with film formation was found to be higher than the flow rate at which film breakdown occurred. The difference in the flow rates for film formation and film breakdown was attributed to contact angle hysteresis. Analysis and experiment, which are in good agreement, indicated that film formation and film breakdown are functions of the advancing and receding angles, respectively.

Simon, F. F.; Hsu, Y. Y.

1972-01-01

351

Temperature hysteresis of the reflection coefficient of leucosapphire in vacuum

NASA Astrophysics Data System (ADS)

We have measured the temperature dependences of light reflection of leucosapphire single crystals upon cyclic variation of temperature in the range of 295-155 K. We have revealed an asymmetric temperature hysteresis of specular reflection, which is accompanied by a change in diffuse reflection. It has been found that the behavior of specular reflection is determined by the temperature dependences of the refractive index and topography of the surface. We assume that temperature changes in the reflection are related to structural phase transitions in the superficial layer.

Tsapenko, B. P.; Tsapenko, A. B.; Bondar', V. G.

2014-02-01

352

A dynamic model for hysteresis in magnetostrictive devices

NASA Astrophysics Data System (ADS)

In this paper, a dynamic model for the description and design of hysteresis in magnetostrictive devices is presented. The model is based on Preisach theory and its dynamic extension. A procedure for determining the Preisach distribution function is given. This procedure is based on neural networks. The model is able to reconstruct both the magnetization relation and the field-strain relation. The model is validated through comparison and prediction of data collected from a typical Terfenol-D sample and a novel experimental technique dedicated to the validation of dynamic models is proposed.

Trapanese, M.; Franzitta, V.; Viola, A.

2014-05-01

353

A storage-extended rating curve for sediment flux estimation

NASA Astrophysics Data System (ADS)

An empirical suspended sediment concentration (SSC) estimation method was tested, which incorporates sediment storage, erosion, and sedimentation history of the upstream river system. It is based on the common rating curve method of which inaccurate SSC estimation is prevailingly caused by the assumption of an over-proportional relationship between SSC and discharge. However, this ignores the fact that SSC depends on the availability of sediments in the river basin as well. Hence, the tested method includes non-linear processes such as the clockwise and counter-clockwise hysteresis during flood discharges. The main characteristic of this new approach is that sediment flux is described as a composition of (i) the base transport of sediments from the catchment area into the river system, (ii) erosion, and (iii) in-situ sedimentation. The first two components are approximated with classical rating curves. The second component depends on (i) a threshold discharge for erosion and (ii) on the sediment availability. Sedimentation is factored as a constant value and it is zero if the discharge exceeds the threshold value. This new model formulation was tested with daily SSC and discharge measurements from the Alpine Rhine River for the period 1 June 2012 to 31 May 2013 at gauging station Diepoldsau, which is located a few kilometres upstream of Lake Constance. The seven empirical parameters of the model were estimated by using an evolutionary algorithm. This optimization algorithm found a threshold for erosion at a discharge of about 500 m3 s-1, a mean concentration of 124 mg l-1 that is lost due to sedimentation, and the mean content of sediment storage in the river bed of about 1.82×1011 kg, which is available for erosion. The results show an clear improvement of SSC estimation: R2 increased to 0.93 while it was 0.73 for the rating curve. Moreover, the new method calculated flood loads, which fitted perfect to measured sediments: e.g. the measured flood load of 7392 mg l-1 (4 June 2013) was approximated with 7357 mg l-1 by the model. To conclude, the additional consideration of erosion and sedimentation processes significantly improves SSC estimations especially during flood events and it offers a reliable way to estimate SSC time series with runoff data.

Fink, Gabriel; Wüest, Alfred

2014-05-01

354

Titania nanorods curve to lower their energy.

Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties. PMID:23794056

Zhang, Hengzhong; Finnegan, Michael P; Banfield, Jillian F

2013-08-01

355

Role of measurement voltage on hysteresis loop shape in Piezoresponse Force Microscopy

The dependence of on-field and off-field hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.

Kim, Yunseok [ORNL; Yang, J.-C. [University of California, Berkeley; Chu, Ying Hao [National Chiao Tung University, Hsinchu, Taiwan; Yu, Pu [University of California, Berkeley; Lu, X. [Xidian University, China; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

2012-01-01

356

We applied the proper orthogonal decomposition (POD) method to extract reduced-order models to efficiently solve nonlinear electromagnetic problems governed by Maxwell's equations with nonlinear hysteresis at low frequency (10 kHz), called static hysteresis, discretized by a finite-element method. We used a new domain-wall-motion hysteresis model for Power MAgnetic Components (POMACs) in the finite-element potential formulation via an efficient implicit-inverse model

Y. Zhai; L. Vu-Quoc

2007-01-01

357

Analysis of power magnetic components with nonlinear static hysteresis: finite-element formulation

We present a new systematic methodology to efficiently solve coupled electromagnetic problems with nonlinear hysteresis at low frequency (10 kHz), called static hysteresis, by the finite-element method. The methodology integrates a new domain-wall-motion hysteresis model for power magnetic components (POMACs) into a finite-element potential formulation via an implicit-inverse model calculation. It uses a novel two-level iterative algorithm incorporating the efficient

Y. Zhai; L. Vu-Quoc

2005-01-01

358

Hysteresis zone or locus - Aerodynamic of bulbous based bodies at low speeds

NASA Technical Reports Server (NTRS)

Experimental data are presented which seem to suggest that a well-defined hysteresis locus on bulbous based bodies at low speeds does not exist. Instead, if the experiment is repeated several times, the entire hysteresis region seems to fill with data rather than trace out a specific hysteresis locus. Data obtained on an oscillating model even at low reduced frequencies may be well defined but when applied to arbitrary motion lead to less accurate results than desired.

Covert, E. E.

1979-01-01

359

Curves, dynamical systems, and weighted point counting

Suppose X is a (smooth projective irreducible algebraic) curve over a finite field k. Counting the number of points on X over all finite field extensions of k will not determine the curve uniquely. Actually, a famous theorem of Tate implies that two such curves over k have the same zeta function (i.e., the same number of points over all extensions of k) if and only if their corresponding Jacobians are isogenous. We remedy this situation by showing that if, instead of just the zeta function, all Dirichlet L-series of the two curves are equal via an isomorphism of their Dirichlet character groups, then the curves are isomorphic up to “Frobenius twists”, i.e., up to automorphisms of the ground field. Because L-series count points on a curve in a “weighted” way, we see that weighted point counting determines a curve. In a sense, the result solves the analogue of the isospectrality problem for curves over finite fields (also know as the “arithmetic equivalence problem”): It states that a curve is determined by “spectral” data, namely, eigenvalues of the Frobenius operator of k acting on the cohomology groups of all ?-adic sheaves corresponding to Dirichlet characters. The method of proof is to show that this is equivalent to the respective class field theories of the curves being isomorphic as dynamical systems, in a sense that we make precise.

Cornelissen, Gunther

2013-01-01

360

NSDL National Science Digital Library

With a laser pointer and some household items, learners can create their own laser light show. They can explore diffuse reflection, refraction and diffraction. The webpage includes a video which shows how to set up the activity and also includes scientific explanation. Because this activity involves lasers, it requires adult supervision.

Houston, Children'S M.

2011-01-01

361

Hysteresis-free operation of suspended carbon nanotube transistors

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes offer high sensitivity and very low power consumption when used as field-effect transistors in nanosensors. Suspending nanotubes between pairs of contacts, rather than attaching them to a surface, has many advantages in chemical, optical or displacement sensing applications, as well as for resonant electromechanical systems. Suspended nanotubes can be integrated into devices after nanotube growth, but contamination caused by the accompanying additional process steps can change device properties. Ultraclean suspended nanotubes can also be grown between existing device contacts, but high growth temperatures limit the choice of metals that can be used as contacts. Moreover, when operated in ambient conditions, devices fabricated by either the post- or pre-growth approach typically exhibit gate hysteresis, which makes device behaviour less reproducible. Here, we report the operation of nanotube transistors in a humid atmosphere without hysteresis. Suspended, individual and ultraclean nanotubes are grown directly between unmetallized device contacts, onto which palladium is then evaporated through self-aligned on-chip shadow masks. This yields pairs of needle-shaped source/drain contacts that have been theoretically shown to allow high nanotube-gate coupling and low gate voltages. This process paves the way for creating ultrasensitive nanosensors based on pristine suspended nanotubes.

Muoth, M.; Helbling, T.; Durrer, L.; Lee, S.-W.; Roman, C.; Hierold, C.

2010-08-01

362

Hysteresis of soft joints embedded with fluid-filled microchannels

Many arthropods are known to achieve dynamic stability during rapid locomotion on rough terrains despite the absence of an elaborate nervous system. While muscle viscoelasticity and its inherent friction have been thought to cause this passive absorption of energy, the role of embedded microstructures in muscles and muscle joints has not yet been investigated. Inspired by the soft and flexible hinge joints present in many of these animals, we have carried out displacement-controlled bending of thin elastic slabs embedded with fluid-filled microchannels. During loading, the slab bends uniformly to a critical curvature, beyond which the skin covering the channel buckles with a catastrophic decrease in load. In the reverse cycle, the buckled skin straightens out but at a significantly lower load. In such a loading–unloading cycle, this localized buckling phenomenon results in a dynamic change in the geometry of the joint, which leads to a significant hysteresis in elastic energy. The hysteresis varies nonlinearly with channel diameters and thicknesses of the slab, which is captured by a simple scaling analysis of the phenomenon.

Ghatak, Animangsu; Majumder, Abhijit; Kumar, Rajendra

2008-01-01

363

Wavenumber selection and hysteresis in nonlinear baroclinic flow

NASA Technical Reports Server (NTRS)

Wavenumber transition and hysteresis in a highly unstable baroclinic flow are investigated using a high-resolution spectral numerical model. As the flow becomes more supercritical, the dominant wave gradually shifts from the most unstable wave predicted by the linear theory to a longer wave with a larger time-averaged amplitude, while the rectified mean flow attains a stronger shear at the center of the channel. The numerical results display a complex hysteresis behavior, which occurs not only between the states of different dominant wavenumbers, but also between the states of identical dominant wavenumber but of different dynamic characteristics. In a certain parameter range three stable states, each with different dominant wavenumber, are possible, and in another parameter range four stable states are possible, among them three stable states with an identical dominant wave. The numerical results suggest that a multiple weather regime exists even without external forcing in which the flow aperiodically varies between two distinct behaviors. The effects of stable higher harmonics are assessed and it is found that their presence contributes not only to the better approximation of the model solutions but also to the selection of the final equilibrium state, due to the chaotic nature of the initial transient period.

Chou, Shih-Hung

1995-01-01

364

Hysteresis and saturation effects with the ALS lattice magnets

The primary purpose of the magnetic measurements performed on the ALS storage ring lattice magnets was to ascertain their compliance with the strict tolerances established for this third-generation synchrotron light source. In the course of the data evaluation, an approximation method has been developed that leads to four-parameter representations of all magnet transfer functions. The expressions for the transfer functions were now used to change the standard working point of the ALS storage ring from the upper to the lower hysteresis branches of all lattice magnet families, and later to ramp the ring from the customary 1.5 GeV to the maximum design energy of 1.9 GeV in one uninterrupted process that did not require any intermediate tune correction. This achievement is all the more remarkable as no remnant fields had directly been measured with any of these magnets. A specific remnant field effect that led to anomalous machine behavior-when trying to recuperate the betatron tunes on the lower hysteresis branch at standard energy could be ascribed to the C-shape of the quadrupole yokes.

Keller, R.

1995-04-01

365

Inelastic compaction, dilation and hysteresis of sandstones under hydrostatic conditions

NASA Astrophysics Data System (ADS)

Sandstones display non-linear and inelastic behaviour such as hysteresis when subjected to cyclic loading. We present three hydrostatic compaction experiments with multiple loading-unloading cycles on Berea and Darley Dale sandstones and explain their hysteretic behaviour using non-linear inelastic compaction and dilation. Each experiment included eight to nine loading-unloading cycles with increasing maximum pressure in each subsequent cycle. Different pressure-volumetric strain relations during loading and unloading were observed. During the first cycles, under relatively low pressures, not all of the volumetric strain is recovered at the end of each cycle whereas at the last cycles, under relatively high pressures, the strain is recovered and the pressure-volumetric strain hysteresis loops are closed. The observed pressure-volumetric strain relations are non-linear and the effective bulk modulus of the sandstones changes between cycles. Observations are modelled with two inelastic deformation processes: irreversible compaction caused by changes in grain packing and recoverable compaction associated with grain contact adhesion, frictional sliding on grains or frictional sliding on cracks. The irreversible compaction is suggested to reflect rearrangement of grains into a more compact mode as the maximum pressure increases. Our model describes the `inelastic compaction envelope' in which sandstone sample will follow during hydrostatic loading. Irreversible compaction occurs when pressure is greater than a threshold value defined by the `inelastic compaction envelope'.

Shalev, Eyal; Lyakhovsky, Vladimir; Ougier-Simonin, Audrey; Hamiel, Yariv; Zhu, Wenlu

2014-05-01

366

National Technical Information Service (NTIS)

This report discusses the use of Pearson curves to give approximate percentage points to intractable distributions, when the first four moments (or three moments and one end-point) are available. It is shown how to fit the curves, and their effectiveness ...

H. Solomon M. A. Stephens

1975-01-01

367

We study the classification problem that arises when two variables—one continuous (x), one discrete (s)—evolve jointly in time. We suppose that the vector x traces out a smooth multidimensional curve, to each point of which the variable s attaches a discrete label. The trace of s thus partitions the curve into different segments whose boundaries occur where s changes value.

Lawrence K. Saul; Mazin G. Rahim

2000-01-01

368

ERIC Educational Resources Information Center

Discusses some of the myths surrounding grading on the curve. Provides a simple explanation of such statistical terms as histograms, relative frequency, normal distribution, mean, and standard deviation. Describes how to restructure the curve, including the program listing for a computer program that will assist the teacher. (TW)

Wall, Charles R.

1987-01-01

369

Prediction of compaction curves

Compaction of soil is one of the major activities in geotechnical engineering involving earthworks. Compaction curve generally features an inverted parabolic shape and is used to find the optimum water content that maximises dry density. Since its introduction by Proctor in 1933, several researchers have provided qualitative explanations for the general shape of the compaction curve. Furthermore, there is a

Nurses Kurucuk; Australia Jayantha Kodikara; Australia Delwyn Fredlund

370

NSDL National Science Digital Library

Take a solid cube with rods attached at diagonally opposite vertices. Hold the rods horizontally and rapidly spin the cube. (See Figure 1.) You should see a curved outline formed by the spinning cube. The objective of this demos is to discover how the straight edges of the cube become curved. The demo is physically based, but can be simulated within various software packages.

Hill, David R.

2003-02-24

371

Tempo curves considered harmful

In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression that a continuous concept of temporal flow has an independent existence, a musical

Peter Desain; Henkjan Honing

1993-01-01

372

ERIC Educational Resources Information Center

Describes the viewing sessions and the holograms of a holographic road show. The traveling exhibits, believed to stimulate interest in physics, include a wide variety of holograms and demonstrate several physical principles. (GA)

Kirkpatrick, Larry D.; Rugheimer, Mac

1979-01-01

373

NSDL National Science Digital Library

Throughout history, there have been many famous curves. In this case, the famous curves profiled here have names such as rhodonea, right strophoid, and the Kampyle of Eudoxus. These curves belong to the world of the mathematical sciences, and they are offered up for teachers and the generally curious by the staff at the School of Mathematics and Statistics at the University of St. Andrews. Visitors can scroll through the complete list of curves (there are over eighty here), and click on each one for an illustration and a listing of the equation that would create such a curve. The site is rounded out by an interactive map that lets users learn about the birthplaces of famous mathematicians from Leibniz to Babbage.

374

Trade show management is a multi-faceted field, requiring a breadth of skills on the part of those engaged in the craft. Whether they go by the title of Show Manager, Director of Marketing, Vice President of Meetings\\/Conventions, or Director of Meetings\\/Conventions, these professionals work with exhibitors, attendees, and service providers to produce their events. The managers of the 200 largest

Susan Gregory; Deborah Breiter

2001-01-01

375

Although the free energy perturbation procedure is exact when an infinite sample of configuration space is used, for finite sample size there is a systematic error resulting in hysteresis for forward and backward simulations. The qualitative behavior of this systematic error is first explored for a Gaussian distribution, then a first-order estimate of the error for any distribution is derived. To first order the error depends only on the fluctuations in the sample of potential energies, {Delta}E, and the sample size, n, but not on the magnitude of {Delta}E. The first-order estimate of the systematic sample-size error is used to compare the efficiencies of various computing strategies. It is found that slow-growth, free energy perturbation calculations will always have lower errors from this source than window-growth, free energy perturbation calculations for the same computing effort. The systematic sample-size errors can be entirely eliminated by going to thermodynamic integration rather than free energy perturbation calculations. When {Delta}E is a very smooth function of the coupling parameter, {lambda}, thermodynamic integration with a relatively small number of windows is the recommended procedure because the time required for equilibration is reduced with a small number of windows. These results give a method of estimating this sample-size hysteresis during the course of a slow-growth, free energy perturbation run. This is important because in these calculations time-lag and sample-size errors can cancel, so that separate methods of estimating and correcting for each are needed. When dynamically modified window procedures are used, it is recommended that the estimated sample-size error be kept constant, not that the magnitude of {Delta}E be kept constant. Tests on two systems showed a rather small sample-size hysteresis in slow-growth calculations except in the first stages of creating a particle, where both fluctuations and sample-size hysteresis are large.

Wood, R.H.; Muehlbauer, W.C.F. (Univ. of Delaware, Newark (United States)); Thompson, P.T. (Swarthmore Coll., PA (United States))

1991-08-22

376

NASA Astrophysics Data System (ADS)

In this work, we propose a method to stabilize a nucleus in the framework of lattice density-functional theory (LDFT) by imposing a suitable constraint. Using this method, the shape of critical nucleus and height of the nucleation barrier can be determined without using a predefined nucleus as input. As an application of this method, we study the nucleation behavior of vapor-liquid transition in nanosquare pores with infinite length and relate the observed hysteresis loop on an adsorption isotherm to the nucleation mechanism. According to the dependence of hysteresis and the nucleation mechanism on the fluid-wall interaction, w , in this work, we have classified w into three regions ( w>0.9 , 0.1?w?0.9 , and w<0.1 ), which are denoted as strongly, moderately, and weakly attractive fluid-wall interaction, respectively. The dependence of hysteresis on the fluid-wall interaction is interpreted by the different nucleation mechanisms. Our constrained LDFT calculations also show that the different transition paths may induce different nucleation behaviors. The transition path dependence should be considered if morphological transition of nuclei exists during a nucleation process.

Men, Yumei; Yan, Qingzhao; Jiang, Guangfeng; Zhang, Xianren; Wang, Wenchuan

2009-05-01

377

NASA Astrophysics Data System (ADS)

Transitions from E to H mode in electrodeless discharges created in pure oxygen at pressures from 10 Pa to 160 Pa are studied. An RF coil is placed at the centre of a long quartz tube and connected to an RF generator via a matching network. The generator operates at a frequency of 13.56 MHz and adjustable power up to 1200 W. The voltage and current on the coil are measured with a commercial voltage probe and a current probe connected to an oscilloscope, while the density of neutral O-atoms is measured with a catalytic probe. The results show the appearance of current and voltage hysteresis at moderately low pressure, the hysteresis being more pronounced at higher pressure. The O-atom density does not depend much on the mode at low pressure. As the pressure increases, a rapid increase of the O-atom density is observed at the transition between the E and the H mode. The hysteresis in the O-atom density is observed as well.

Zaplotnik, R.; Vesel, A.; Mozetic, M.

2011-09-01

378

Hysteresis behaviour of highly elastic multigraft copolymers with a polyisoprene (PI) backbone and branched polystyrene (PS) arms has been interpreted by applying the extended non-affine tube model of filler reinforced rubber elasticity (dynamic flocculation model), which takes into account that conformational fluctuations in bulk networks are strongly suppressed by packing effects. Originally, this model was developed to describe hyperelasticity of unfilled networks, and later, stress softening and hysteresis of filler reinforced elastomer materials like carbon black and silica filled rubbers. The evaluation of stress softening is obtained via pre-strain dependent hydrodynamic amplification of the rubber matrix by a fraction of rigid filler clusters with virgin filler filler bonds. The filler-induced hysteresis is described by a cyclic breakdown and re-aggregation of the residual fraction of more soft filler clusters with already broken filler filler bonds. We show, for the first time that the developed concept is in fair agreement with experimental stress strain data of superelastic PI PS multigraft copolymers. Depending on the PS-content and their functionality multigraft copolymers form microphase separated structures according to the constituting block copolymer concept, where the PS arms act as multi-domains in a PI matrix. The adaptation of the model is based on the assumption that the PS-domains are acting similar to filler clusters. The obtained microscopic material parameters appear reasonable for the description of the structure and mechanical properties of multigraft copolymers.

Staudinger, Ulrike [University of Jena, Institute of Materials Science and Technology, Jena Germany; Schlegel, Ralf [Fraunhofer IWM, Freiburg, German; Weidisch, Roland [Polymer Research Institute, Dresden Germany; Fritzsche, Juliane [Deutsches Institut fur Kautschuktechnologie e.V., Hannover, Germany; Kluppel, Manfred [Deutsches Institut fur Kautschuktechnologie e.V., Hannover, Germany; Heinrich, G. [Polymer Research Institute, Dresden Germany; Mays, Jimmy [ORNL; Uhrig, David [ORNL; Hadjichristidis, Nikos [University of Athens, Athens, Greece

2008-01-01

379

NASA Astrophysics Data System (ADS)

A physics-based fractional-order Maxwell resistive capacitor (FOMRC) model is proposed to characterize nonlinear hysteresis and creep behaviors of a piezoelectric actuator (PEA). The Maxwell resistive capacitor (MRC) model is interpreted physically in the electric domain for PEAs. Based on this interpretation, the MRC model is modified to directly describe the relationship between the input voltage and the output displacement of a PEA. Then a procedure is developed to identify the parameters of the MRC model. This procedure is capable of being carried out using the measured input and output of a PEA only. A fractional-order dynamics is integrated into the MRC model to describe the effect of creep, as well as the detachment of hysteresis loops caused by creep. Moreover, the inverse FOMRC model is constructed to compensate for hysteresis and creep in an open-loop positioning application of PEAs. Simulation and experiments are carried out to validate the proposed model. The PEA compensated by the inverse FOMRC model shows an excellent linear behavior.

Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich; Qi, Naiming

2013-11-01

380

Study of spin crossover nanoparticles thermal hysteresis using FORC diagrams on an Ising-like model

NASA Astrophysics Data System (ADS)

Recent developments in the synthesis and characterization of spin crossover (SCO) nanoparticles and their prospects of switching at molecular level turned these bistable compounds into possible candidates for replacing the materials used in recording media industry for development of solid state pressure and temperature sensors or for bringing contributions in engineering. Compared to bulk samples with the same chemical structure, SCO nanoparticles display different characteristics of the hysteretic and relaxation properties like the shift of the transition temperature towards lower values along with decrease of the hysteresis width with nanoparticles size. Using an Ising-like model with specific boundary conditions within a Monte Carlo procedure, we here reproduce most of the hysteretic properties of SCO nanoparticles by considering the interaction between spin crossover edge molecules and embedding surfactant molecules and we propose a complex analysis concerning the effect of the interactions and sizes during the thermal transition in systems of SCO nanoparticles by using the First Order Reversal Curves diagram method and by comparison with similar effects in mixed crystal systems.

Atitoaie, Alexandru; Tanasa, Radu; Stancu, Alexandru; Enachescu, Cristian

2014-11-01

381

NSDL National Science Digital Library

Activation of Ras proteins underlies functional decisions in diverse cell types. Two molecules, Ras-GRP and SOS (Ras–guanine nucleotide–releasing protein and Son of Sevenless, respectively), catalyze Ras activation in lymphocytes. Binding of active Ras to the allosteric pocket of SOS markedly increases the activity of SOS. Thus, there is a positive feedback loop regulating SOS. Combining in silico and in vitro studies, we demonstrate that “digital” signaling in lymphocytes (cells are “on” or “off”) is predicated on this allosteric regulation of SOS. The SOS feedback loop leads to hysteresis in the dose-response curve, which may enable T cells to exhibit “memory” of past encounters with antigen. Ras activation by Ras-GRP alone is “analog” (a graded increase in activation in response to an increase in the amplitude of the stimulus). We describe how the complementary analog (Ras-GRP) and digital (SOS) pathways act on Ras to efficiently convert analog input to digital output and make predictions regarding the importance of digital signaling in lymphocyte function and development.

Arup K. Chakraborty (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Jayajit Das (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Julie Zikherman (University of California; Department of Medicine; REV); Ming Yang (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Christopher C. Govern (Massachusetts Institute of Technology; Department of Chemical Engineering; REV); Mary Ho (University of California; Department of Anatomy; REV)

2009-04-14

382

NSDL National Science Digital Library

The Idaho State University Department of Physics conducts science demonstration shows at S. E. Idaho schools. Four different presentations are currently available; "Forces and Motion", "States of Matter", "Electricity and Magnetism", and "Sound and Waves". Information provided includes descriptions of the material and links to other resources.

Shropshire, Steven

2009-04-06

383

ERIC Educational Resources Information Center

Having students show their skills in three dimensions, known as performance-based assessment, dates back at least to Socrates. Individual schools such as Barrington High School--located just outside of Providence--have been requiring students to actively demonstrate their knowledge for years. The Rhode Island's high school graduating class became…

Cech, Scott J.

2008-01-01

384

ERIC Educational Resources Information Center

Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)

Mathieu, Aaron

2000-01-01

385

ERIC Educational Resources Information Center

Describes the process of selecting judges for a Blue Ribbon Art Show (Springfield, Missouri). Used adults (teachers, custodians, professional artists, parents, and principals) chosen by the Willard South Elementary School art teacher to judge student artwork. States that nominated students received blue ribbons. (CMK)

Bowen, Judy Domeny

2002-01-01

386

A kill curve for Phanerozoic marine species

NASA Technical Reports Server (NTRS)

A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to li inverted question markmit choices of extinction mechanisms.

Raup, D. M.

1991-01-01

387

Dissociative Recombination without a Curve Crossing

NASA Technical Reports Server (NTRS)

Ab initio calculations show that a curve crossing is not always needed for a high dissociative- recombination cross section. For HeH(+), in which no neutral states cross the ion potential curve, dissociative recombination is driven by the nuclear kinetic-energy operator on adiabatic potential curves. The kinetic-energy derivative operator allows for capture into repulsive curves that are outside of the classical turning points for the nuclear motion. The dominant dissociative route is the C (2)Sigma(+) state leading to H(n = 2) atoms. An analogous mechanism is proposed for the dissociative recombination of H3(+).

Guberman, Steven L.

1994-01-01

388

NASA Astrophysics Data System (ADS)

The flux jumps, the second peak and the irreversible magnetic field in the magnetization hysteresis cycles have been investigated in the high temperature superconductor YBa2Cu3O7- single crystals. These cycles were obtained for different temperature values, the applied magnetic fields up to 6 T and the angle between the applied magnetic field and c-axis. The magnetization curves exhibit a remarkable second peak fishtail, this second peak was not observed for the low temperature, but we observed the flux jumps saw tooth. The temperature dependence of the irreversible magnetic field, Hirr, for the applied magnetic field perpendicular to the ab planes is given by an extended expression, Hirr ? (1-T/Tc )?, where ? is a constant, the Abrikosov flux dynamics can explain this behavior. The Hirr as a function of has been strongly influenced by the flux pinning and the thermally assisted flux motion.

Taoufik, A.; Ramzi, A.; Senoussi, S.; Labrag, A.

2004-05-01

389

Hysteresis of the Kuroshio penetrations into the South China Sea

NASA Astrophysics Data System (ADS)

An idealized problem of a western boundary current of Munk thickness LM flowing across a gap in a ridge is considered using a single-layer depth-averaged approach. When the gap (of width 2 a) is narrow, a <= 3.12 LM, viscous forces alone restrict penetration of the current through the gap. However, the gap is ``leaky'' in the linear case and some very weak flow still passes through. For larger gap width, the boundary current may leap across the gap due to inertia characterized by the Reynolds number Re, completely choking off water exchange between the two basins. For a >= 4.55 LM the flow may be in one of two regimes (penetrating or leaping) for the same parameters depending on previous evolution. The penetrating branch solutions become unsteady with eddies forming west of the gap between the two counter-flowing zonal jets. As the boundary current slowly accelerates, transition from the penetrating to leaping regime happens when the width of a zonal jet near the gap becomes comparable with a, implying the Reynolds number ReP ~= (a/LM)3. On the other hand as the boundary current slowly decelerates, the leaping regime persists while the meridional advection dominates the ? -effect in a wiggle of the current core within the gap, implying that the leaping regime breaks at ReL ~= a/LM. Thus hysteresis occurs over the range of Reynolds numbers ReL < Re < ReP. An interesting application of this problem is to the Kuroshio current in Luzon Strait. The theory suggests that normally the Kuroshio can leap across Luzon Strait (LQP >= a). However, during periods when its strength is substantially reduced, it may penetrate into the South China Sea as a loop current. Thus multiple states and hysteresis are likely to occur. Because of the possible hysteresis, in analyzing the observational data, it is important to correlate the Kuroshio penetrations not only with the parameters describing the present state of the current, but also to take into account its history. For example, Farris and Wimbush (1996) found a relationship between the loop-current stage (derived from satellite infrared images) and the wind-stress history: the Kuroshio penetrations occur when the time-integrated strength of the northeast monsoon exceeds a threshold value. This is in qualitative agreement with the present theory in the sense that the penetrations occur when the Kuroshio is weakened by the monsoon blowing in the opposite direction.

Sheremet, V. A.

2001-12-01

390

NSDL National Science Digital Library

The Show-Me Center is a partnership of four NSF-sponsored middle grades mathematics curriculum development Satellite Centers (University of Wisconsin, Michigan State University, University of Montana, and the Educational Development Center). The group's website provides "information and resources needed to support selection and implementation of standards-based middle grades mathematics curricula." The Video Showcase includes segments on Number, Algebra, Geometry, Measure, and Data Analysis, with information on ways to obtain the complete video set. The Curricula Showcase provides general information, unit goals, sample lessons and teacher pages spanning four projects: the Connected Mathematics Project (CMP), Mathematics in Context (MiC), MathScape: Seeing and Thinking Mathematically, and Middle Grades Math Thematics. The website also posts Show-Me Center newsletters, information on upcoming conferences and workshops, and links to resources including published articles and unpublished commentary on mathematics school reform.

391

NSDL National Science Digital Library

This lesson plan assesses student interpretation of graphs utilizing cooperative learning to further students understanding. Types of graphs used are horizontal and vertical bar graphs, picture graphs, and pictographs. In the lesson students play a game called the Graphing Game Show, in which they must work as a team to answer questions about specific graphs. The lesson includes four student resource worksheets and suggestions for extension and differentiation.

2011-01-01

392

NASA Astrophysics Data System (ADS)

We present the results of an experimental study on the effects of hysteresis on capillary trapping and relative permeability of CO2/brine systems at reservoir conditions. We performed thirty unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, low- and high-permeability Berea and Nugget sandstones. The experiments were carried out at various flow rates with both supercritical CO2 (scCO2)/brine and gaseous CO2 (gCO2)/brine fluid systems. The unsteady-state experiments were carried out with a wide range of flow rates to establish a broad range of initial brine saturations (Swi). This allowed investigation of the sensitivity of residual trapped CO2 saturation (S) to changes in Swi. The values were successfully compared with those available in the literature. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO2. Post-imbibition dissolution of trapped CO2 and formation of dissolution front was also investigated. During the steady-state experiments, scCO2 and brine were co-injected with monotonically increasing or decreasing fractional flows to perform drainage and imbibition processes. We carried out seven sets of steady-state flow tests with various trajectories generating a comprehensive group of relative permeability hysteresis curves. The scanning curves revealed distinct features with potentially important implications for storage of scCO2 in geological formations. For both series of experiments, the ratio of S to initial CO2 saturation (1- Swi) was found to be much higher for low initial CO2 saturations. The results indicate that very promising fractions (about 49 to 83%) of the initial CO2 saturation can be stored through capillary trapping.

Akbarabadi, Morteza; Piri, Mohammad

2013-02-01

393

Cauchy-Stieltjes integral on time scales in banach spaces and hysteresis operators

NASA Astrophysics Data System (ADS)

The play operator has a fundamental importance in the theory of hysteresis. It was studied in various settings as shown by P. Krejci and Ph. Laurençot in 2002. In that work it was considered the Young integral in the frame of Hilbert spaces. Here we study the play in the frame of the regulated functions (that is: the ones having only discontinuities of the first kind) on a general time scale T (that is: with T being a nonempty closed set of real numbers) with values in a Banach space. We will be showing that the dual space in this case will be defined as the space of operators of bounded semivariation if we consider as the bilinearity pairing the Cauchy-Stieltjes integral on time scales.

Barbanti, Luciano; Damasceno, Berenice Camargo

2012-11-01

394

Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water

The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25?cm2 active area create a serpentine flow-field on an active area of 100?cm2 and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums.

Park, Kiwon; Lee, Jungkoo; Kim, Hyung-Man; Choi, Kap-Seung; Hwang, Gunyong

2014-01-01

395

Entropy generation of droplet motion with surface tension hysteresis in a closed microchannel

NASA Astrophysics Data System (ADS)

A transient heat transfer and entropy analysis is conducted to investigate the processes of thermocapillary droplet motion in closed microchannels. Both theoretical predictions and experimental data are presented for time-dependent temperature changes during the droplet acceleration. This paper develops a predictive model of the entropy production due to thermal and fluid irreversibilities in the microchannel. Thermocapillary, pressure and friction forces are modelled within the droplet, as well as surface tension hysteresis during start-up of the droplet motion. The spatial temperature change in the axial direction is measured experimentally, as well as the displacement of the droplet over time. The variation of the entropy generation number is reported for open and closed channels. Close agreement is obtained between the predicted and experimental data. The results show that water droplets have lower thermal and fluid irreversibilities than toluene and mineral oil.

Odukoya, A.; Naterer, G. F.; Dincer, I.

2011-09-01

396

Magnetic Biasing of a Ferroelectric Hysteresis Loop in a Multiferroic Orthoferrite

NASA Astrophysics Data System (ADS)

In a multiferroic orthoferrite Dy0.7Tb0.3FeO3, which shows electric-field-(E-)driven magnetization (M) reversal due to a tight clamping between polarization (P) and M, a gigantic effect of magnetic-field (H) biasing on P-E hysteresis loops is observed in the case of rapid E sweeping. The magnitude of the bias E field can be controlled by varying the magnitude of H, and its sign can be reversed by changing the sign of H or the relative clamping direction between P and M. The origin of this unconventional biasing effect is ascribed to the difference in the Zeeman energy between the +P and -P states coupled with the M states with opposite sign.

Tokunaga, Y.; Taguchi, Y.; Arima, T.; Tokura, Y.

2014-01-01

397

Spatial Frequency Integration During Active Perception: Perceptual Hysteresis When an Object Recedes

As we move through the world, information about objects moves to different spatial frequencies. How the visual system successfully integrates information across these changes to form a coherent percept is thus an important open question. Here we investigate such integration using hybrid faces, which contain different images in low and high spatial frequencies. Observers judged how similar a hybrid was to each of its component images while walking toward or away from it or having the stimulus moved toward or away from them. We find that when the stimulus is approaching, observers act as if they are integrating across spatial frequency separately at each moment. However, when the stimulus is receding, observers show a perceptual hysteresis effect, holding on to details that are imperceptible in a static stimulus condition. Thus, observers appear to make optimal inferences by sticking with their previous interpretation when losing information but constantly reinterpreting their input when gaining new information.

Brady, Timothy F.; Oliva, Aude

2012-01-01

398

Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water

NASA Astrophysics Data System (ADS)

The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25 cm2 active area create a serpentine flow-field on an active area of 100 cm2 and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums.

Park, Kiwon; Lee, Jungkoo; Kim, Hyung-Man; Choi, Kap-Seung; Hwang, Gunyong

2014-04-01

399

Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water.

The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25?cm(2) active area create a serpentine flow-field on an active area of 100?cm(2) and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums. PMID:24699531

Park, Kiwon; Lee, Jungkoo; Kim, Hyung-Man; Choi, Kap-Seung; Hwang, Gunyong

2014-01-01

400

Education Statistics Slide Show

NSDL National Science Digital Library

Created by Grace York, coordinator of the University of Michigan's Documents Center, the Education Statistics Slide Show is an online presentation demonstrating how to locate, obtain, and manipulate educational data on the Web. The presentation consists of 72 slides and offers instruction on the use of several Websites including the US Census Bureau's American Factfinder site (see the April 2, 1999 Scout Report), the Center for International Earth Science Information Network (CIESIN) Census Mapping site, the National Center for Education Statistics (NCES) site, the FEDSTATS site (see the May 30, 1997 Scout Report), and many more. The tutorial presentation also provides ten practice questions and a detailed Webliography.

401

Hysteresis compensation of a porous silicon relative humidity sensor using ANN technique

This paper presents a simple technique based on well-known multilayer perceptron (MLP) neural network with back propagation training algorithm for compensating the significant error due to hysteresis in a porous silicon relative humidity sensor. The porous silicon humidity sensor has been fabricated, and its hysteresis with increasing and decreasing relative humidity has been determined experimentally by a novel phase detection

Tariqul Islam; Hiranmay Saha

2006-01-01

402

Hysteresis and nonlinearity compensation of relative humidity sensor using support vector machines

Based on support vector machine (SVM) technique, a novel method for hysteresis and nonlinearity compensation of a relative humidity sensor has been investigated. The compensation method consists of a two-stage procedure. First, a SVM is used to perform the hysteresis error compensation of the sensor. Then, a second SVM is utilized to compensate the nonlinearity error in the response characteristics

Xiaodong Wang; Meiying Ye

2008-01-01

403

How structure sensitive parameters derived from hysteresis loops can provide nondestructive information about the evolution of the microstructure of cold rolled low carbon steel as a result of recovery and recrystallization processes during the annealing is shown. The coercive field, remanent induction and hysteresis losses can be used to monitor the decrease in the dislocation density during recovery. These parameters

A. Martínez-de-Guerenu; K. Gurruchaga; F. Arizti

2007-01-01

404

Modeling microstructural effects on hysteresis loops with the same maximum flux density

Microstructural attributes such as grain size d and dislocation density ?d affect the hysteretic magnetic properties of steels because they affect domain wall movement and pinning. In an earlier paper, a model was proposed for computing hysteresis loops based on the effect of grain size and dislocation density. In that paper, hysteresis loops were compared that all had the same

M. J. Sablik; F. J. G. Landgraf

2003-01-01

405

Interpretation of hysteresis loops of cobalt-rare-earth single particles

The magnetic behavior of single particles of Co5Sm is being studied in an effort to understand the origin of the coercive force in cobalt rare earths. It has been found that the complex hysteresis loops often observed, containing several magnetization discontinuities, can be analyzed as the linear sum of single-discontinuity hysteresis loops, implying that regions of a particle can act

J. Becker

1971-01-01

406

Impacts of Transformer Core Hysteresis Formation on Stability Domain of Ferroresonance Modes

This paper investigates impacts of various formations of hysteresis on the stability domain of ferroresonance modes of a voltage transformer (VT). Based on four different hysteretic and two single-valued polynomial models, ferroresonance behaviors of the VT are studied. The hysteretic models are developed based on the Preisach theory. The first hysteretic model accurately duplicates the measured hysteresis loops of the

Afshin Rezaei-Zare; Reza Iravani; Majid Sanaye-Pasand

2009-01-01

407

Phosphorus–discharge hysteresis during storm events along a river catchment: the River Swale, UK

Variations in the concentration of determinands in rivers during storms often result in a hysteresis effect with different concentration during the rising and falling limb of the hydrograph. This is investigated here by measuring total phosphorus, particulate phosphorus and soluble reactive phosphorus at 3-h intervals at three points along the River Swale. Phosphorus concentration–discharge hysteresis from 10 storm events were

Michael J. Bowes; William A. House; Robin A. Hodgkinson; David V. Leach

2005-01-01

408

Modeling plastic deformation effects in steel on hysteresis loops with the same maximum flux density

Plastic deformation affects the hysteretic magnetic properties of steels because it changes the dislocation density, which affects domain-wall movement and pinning, and also because it places the specimen under residual strain. An earlier paper proposed a model for computing hysteresis loops on the basis of the effect of grain size d and dislocation density ?d. In that paper, hysteresis loops

Martin J. Sablik; Taeko Yonamine; Fernando J. G. Landgraf

2004-01-01

409

Large melting point hysteresis of Ge nanocrystals embedded inSiO2

The melting behavior of Ge nanocrystals embedded within SiO{sub 2} is evaluated using in situ transmission electron microscopy. The observed melting point hysteresis is large ({+-} 17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy.

Xu, Q.; Sharp, I.D.; Yuan, C.W.; Yi, D.O.; Liao, C.Y.; Glaeser,A.M.; Minor, A.M.; Beeman, J.W.; Ridgway, M.C.; Kluth, P.; Ager III,J.W.; Chrzan, D.C.; Haller, E.E.

2006-05-04

410

An analytical motor for a permanent magnet hysteresis hybrid synchronous motor has been developed. A microprocessor-based field oriented control scheme has been successfully experimented for a laboratory magnet hysteresis motor. A scheme for measuring the torque angle is proposed. The test results confirm the improvement of the dynamic performances using a field-oriented control strategy

J. Qian; M. Azizur Rahman

1991-01-01

411

We present the hysteresis of the response of the poly(N-isopropylacrylamide)-co-acrylic acid microgel-based etalons to solution temperature and pH changes. We find that the optical hysteresis of the etalon can be controlled using various solution ionic strengths and/or counterions, as well as by varying the microgel's acrylic acid concentration. PMID:23425938

Hu, Liang; Serpe, Michael J

2013-04-01

412

Are Driving and Overtaking on Right Curves More Dangerous than on Left Curves?

It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed that drivers behave differently depending on the curve direction where both speed and acceleration were higher on right than left curves. The implication of this study is that curve direction should be taken into consideration to a greater extent when designing and redesigning curves. It appears that the driver and the vehicle are influenced by different infrastructure factors depending on the curve direction. In addition, the results suggest that the vehicle dynamics response alone cannot explain the higher crash risk in right curves. Further studies of the links between driver, vehicle, and highway characteristics are needed, such as naturalistic driving studies, to identify the key safety indicators for highway safety.

Othman, Sarbaz; Thomson, Robert; Lanner, Gunnar

2010-01-01

413

Are driving and overtaking on right curves more dangerous than on left curves?

It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed that drivers behave differently depending on the curve direction where both speed and acceleration were higher on right than left curves. The implication of this study is that curve direction should be taken into consideration to a greater extent when designing and redesigning curves. It appears that the driver and the vehicle are influenced by different infrastructure factors depending on the curve direction. In addition, the results suggest that the vehicle dynamics response alone cannot explain the higher crash risk in right curves. Further studies of the links between driver, vehicle, and highway characteristics are needed, such as naturalistic driving studies, to identify the key safety indicators for highway safety. PMID:21050608

Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

2010-01-01

414

Estimating Item Characteristics Curves.

National Technical Information Service (NTIS)

A simulation study of the effectiveness of the following four item characteristic curve estimation programs was conducted: ANCILLES, OGIVIA (from U. S. Civil Service Commission); LOGIST (from Educational Testing Service); and simple transformations to the...

M. J. Ree

1978-01-01

415

NSDL National Science Digital Library

This interactive demo illustrates the generation of a logistic curve. This demo is appropriate for a pre-calculus course, but is quite effective in a calculus class immediately after a discussion of inflection points.

Roberts, Lila F.; Hill, David R.

2002-02-03

416

Creasing Instability of Hydrogel Surfaces: Nucleation, Growth Dynamics & Hysteresis

NASA Astrophysics Data System (ADS)

The free surface of a hydrogel film supported on a rigid substrate will become unstable to formation of sharp folds when placed under sufficiently large compressive swelling stresses. We seek to exploit this mechanical creasing instability to design smart polymer films with reversible stimuli-responsive properties, however many fundamental questions remain about the mechanism and dynamics of crease formation. We have studied the process of crease nucleation and growth, as well as presence of hysteresis in the level of compressive stress at which folds form and disappear using temperature-responsive surface attached hydrogels. To further understand these processes, we have also studied the influence of skin layers coated on the gel surface and defects in the gel. These studies provide important insights into the mechanism of crease formation and how to control the onset and disappearance of creases.

Hayward, Ryan; Yoon, Jinhwan; Kim, Jungwook

2010-03-01

417

Hysteresis of glaciations in the Permo-Carboniferous

NASA Astrophysics Data System (ADS)

hysteresis of glaciations in the Permo-Carboniferous is simulated in an iterative energy balance model with 84 scenarios of varied orbital elements, CO2 levels, and glacial modes. Gondwana attains its glacial maximum when CO2 is roughly the same or slightly higher than the preindustrial level. Once glaciated it maintains a large ice covered area under higher CO2 levels up to 4 to 6 times of the preindustrial value followed by an abrupt disappearance of ice beyond this threshold. The solutions arrived at by iteration indicate the existence of parameter thresholds of glaciations and deglaciations which lead to the alternating extremes of glacial coverage. Dominated by the large seasonal cycle over land, the concentrated geography of the Permo-Carboniferous is more sensitive to the CO2-forced climate than sparsely distributed land. Our conceptual modeling agrees well with the recent geological evidence of intercalations of three glaciations and two lacunae of deglaciations in this geologic time.

Zhuang, Kelin; North, Gerald R.; Giardino, John R.

2014-03-01

418

Hysteresis in flow patterns in annular swirling jets

This study investigates the influence of swirl on the mean cold flowfield of an annular jet with a stepped-conical expansion. Both the axial and azimuthal velocity components are measured using a two component Laser Doppler Anemometry system in forward scattering mode. A detailed description of the radial profiles of both mean axial and azimuthal velocity as well as three components of the Reynolds stress are given. Four different jets are identified as a function of the swirl number: 'Closed Jet Flow', 'Open Jet Flow Low Swirl', 'Open Jet Flow High Swirl' and 'Coanda Jet Flow'. These flow patterns change with varying swirl number and there exists hysteresis when increasing and subsequently decreasing the swirl. Also a method for jet identification based upon pressure measurements is presented to replace the time consuming LDA measurements. (author)

Vanierschot, M.; Van den Bulck, E. [Katholieke Universiteit Leuven, Department of Mechanical Engineering, Division of Applied Mechanics and Energy Conversion, Celestijnenlaan 300A, B-3001 Heverlee (Belgium)

2007-05-15

419

The thermodynamic origin of hysteresis in insertion batteries.

Lithium batteries are considered the key storage devices for most emerging green technologies such as wind and solar technologies or hybrid and plug-in electric vehicles. Despite the tremendous recent advances in battery research, surprisingly, several fundamental issues of increasing practical importance have not been adequately tackled. One such issue concerns the energy efficiency. Generally, charging of 10(10)-10(17) electrode particles constituting a modern battery electrode proceeds at (much) higher voltages than discharging. Most importantly, the hysteresis between the charge and discharge voltage seems not to disappear as the charging/discharging current vanishes. Herein we present, for the first time, a general explanation of the occurrence of inherent hysteretic behaviour in insertion storage systems containing multiple particles. In a broader sense, the model also predicts the existence of apparent equilibria in battery electrodes, the sequential particle-by-particle charging/discharging mechanism and the disappearance of two-phase behaviour at special experimental conditions. PMID:20383130

Dreyer, Wolfgang; Jamnik, Janko; Guhlke, Clemens; Huth, Robert; Moskon, Joze; Gaberscek, Miran

2010-05-01

420

Cumulative growth of minor hysteresis loops in the Kolmogorov model

The phenomenon of nonrepeatability of successive remagnetization cycles in Co/M (M = Pt, Pd, Au) multilayer film structures is explained in the framework of the Kolmogorov crystallization model. It is shown that this model of phase transitions can be adapted so as to adequately describe the process of magnetic relaxation in the indicated systems with 'memory.' For this purpose, it is necessary to introduce some additional elements into the model, in particular, (i) to take into account the fact that every cycle starts from a state 'inherited' from the preceding cycle and (ii) to assume that the rate of growth of a new magnetic phase depends on the cycle number. This modified model provides a quite satisfactory qualitative and quantitative description of all features of successive magnetic relaxation cycles in the system under consideration, including the surprising phenomenon of cumulative growth of minor hysteresis loops.

Meilikhov, E. Z., E-mail: meilikhov@imp.kiae.ru; Farzetdinova, R. M. [National Research Centre Kurchatov Institute (Russian Federation)] [National Research Centre Kurchatov Institute (Russian Federation)

2013-01-15

421

Isotropic vector hysteresis modeling with feed-forward neural networks

NASA Astrophysics Data System (ADS)

A new vector hysteresis model is presented, based on the function approximation capabilities of feed-forward neural networks. Two-dimensional circular and elliptical magnetization of laminated SiFe steel sheets can be successfully handled by the model. A feed-forward neural network with four inputs, derived at each time step from the time-dependent magnetic induction vector, yields an accurate prediction of the magnetic field strength vector. Measurement results for a steel sheet sample are used to train and test the neural network. The model accuracy is good and can be easily adapted to the requirements of the application by extending or reducing the network training set and thus the required amount of measurement data. Besides, the presented technique is fast, requires no large data set, and applies standard neural network algorithms. Future extension of the model to other magnetization patterns is possible.

Makaveev, Dimitre; Dupré, Luc; de Wulf, Marc; Melkebeek, Jan

2002-05-01

422

Hysteresis modeling of sequential application of orthogonal fields

NASA Astrophysics Data System (ADS)

In a cumulative effort to characterize the sizes, shapes, and distributions of the domains of the structurally superior high strength steels, a characteristic magnetization measurement and a Preisach model are presented to explain and model the distinctive trends observed in the data. The study investigates the effect of a constant transverse magnetic field and a cycling longitudinal magnetic field, applied sequentially, on the major hysteresis loop of solid cylinders of high strength steel. A coupled-hysteron vector Preisach model is extended to model the longitudinal magnetization of the samples under the effect of an applied transverse field. Insights about the microstructure of the rods and the contribution of different domains and magnetization mechanisms to the magnetic response are drawn.

ElBidweihy, H.; Della Torre, E.; Burgy, C. D.

2014-05-01

423

Dynamics and hysteresis in square lattice artificial spin ice

NASA Astrophysics Data System (ADS)

Dynamical effects under geometrical frustration are considered in a model for artificial spin ice on a square lattice in two dimensions. Each island of the spin ice has a three-component Heisenberg-like dipole moment subject to shape anisotropies that influence its direction. The model has real dynamics, including rotation of the magnetic degrees of freedom, going beyond the Ising-type models of spin ice. The dynamics is studied using a Langevin equation solved via a second-order Heun algorithm. Thermodynamic properties such as the specific heat are presented for different couplings. A peak in specific heat is related to a type of melting-like phase transition present in the model. Hysteresis in an applied magnetic field is calculated for model parameters where the system is able to reach thermodynamic equilibrium.

Wysin, G. M.; Moura-Melo, W. A.; Mól, L. A. S.; Pereira, A. R.

2013-04-01

424

Origin of the constricted hysteresis loop in cobalt ferrites revisited

NASA Astrophysics Data System (ADS)

A series of Co ferrites (Co xFe 3- xO 4 ( x=0-1)) were prepared using solid-state method in this work. The aging effect of their structures and constrictions of hysteresis loops under low magnetic field were investigated. It was found that during the aging process, the migration of trivalent (bivalent) ions between tetrahedral (A-site) and octahedral (B-site) coordination induced a shrinking of the lattice, which would expand again due to the precipitation of Fe 3+ after a much longer aging time. The first process caused a pronounced constriction of the loops, due to the uniaxial anisotropy led by this migration. The depression of constriction could attribute to both the expansion of lattice and the change of ionic ratios as a result of the second-phase-precipitation. The impacts of Co content, aging time and temperature upon the constriction were also discussed.

Zhang, Hong-guo; Zhang, Yu-Jie; Wang, Weng-Hong; Wu, Guang-Heng

2011-08-01

425

\\u000a This paper is a survey on the arithmetic of ?-curves: the elliptic curves defined over number fields which are isogenous to\\u000a all their Galois conjugates. Our purpose is to review some results concerning their basic properties such as: the moduli classification,\\u000a fields of definition, relationship with abelian varieties of GL2-type, and optimal quotients. Most of the results were separately\\u000a published

Josep González; Joan-Caries Lario; Jordi Quer

426

Causes and implications of colloid and microorganism retention hysteresis

NASA Astrophysics Data System (ADS)

Experiments were designed to better understand the causes and implications of colloid and microorganism retention hysteresis with transients in solution ionic strength (IS). Saturated packed column experiments were conducted using two sizes of carboxyl modified latex (CML) microspheres (0.1 and 1.1 ?m) and microorganisms (coliphage ?X174 and E. coli D21g) under various transient solution chemistry conditions, and 360 ?m Ottawa sand that was subject to different levels of cleaning, namely, a salt cleaning procedure that removed clay particles, and a salt + acid cleaning procedure that removed clay and reduced microscopic heterogeneities due to metal oxides and surface roughness. Comparison of results from the salt and salt + acid treated sand indicated that microscopic heterogeneity was a major contributor to colloid retention hysteresis. The influence of this heterogeneity increased with IS and decreasing colloid/microbe size on salt treated sand. These trends were not consistent with calculated mean interaction energies (the secondary minima), but could be explained by the size of the electrostatic zone of influence (ZOI) near microscopic heterogeneities. In particular, the depth of local minima in the interaction energy has been predicted to increase with a decrease in the ZOI when the colloid size and/or the Debye length decreased (IS increased). The adhesive interaction was therefore largely irreversible for smaller sized 0.1 ?m CML colloids, whereas it was reversible for larger 1.1 ?m CML colloids. Similarly, the larger E. coli D21g exhibited greater reversibility in retention than ?X174. However, direct comparison of CML colloids and microbes was not possible due to differences in size, shape, and surface properties. Retention and release behavior of CML colloids on salt + acid treated sand was much more consistent with mean interaction energies due to reduction in microscopic heterogeneities.

Bradford, Scott A.; Kim, Hyunjung

2012-09-01

427

Finite element analysis of hysteresis effects in piezoelectric transducers

NASA Astrophysics Data System (ADS)

The design of ultrasonic transducers for high power applications, e.g. in medical therapy or production engineering, asks for effective computer aided design tools to analyze the occurring nonlinear effects. In this paper the finite-element-boundary-element package CAPA is presented that allows to model different types of electromechanical sensors and actuators. These transducers are based on various physical coupling effects, such as piezoelectricity or magneto- mechanical interactions. Their computer modeling requires the numerical solution of a multifield problem, such as coupled electric-mechanical fields or magnetic-mechanical fields as well as coupled mechanical-acoustic fields. With the reported software environment we are able to compute the dynamic behavior of electromechanical sensors and actuators by taking into account geometric nonlinearities, nonlinear wave propagation and ferroelectric as well as magnetic material nonlinearities. After a short introduction to the basic theory of the numerical calculation schemes, two practical examples will demonstrate the applicability of the numerical simulation tool. As a first example an ultrasonic thickness mode transducer consisting of a piezoceramic material used for high power ultrasound production is examined. Due to ferroelectric hysteresis, higher order harmonics can be detected in the actuators input current. Also in case of electrical and mechanical prestressing a resonance frequency shift occurs, caused by ferroelectric hysteresis and nonlinear dependencies of the material coefficients on electric field and mechanical stresses. As a second example, a power ultrasound transducer used in HIFU-therapy (high intensity focused ultrasound) is presented. Due to the compressibility and losses in the propagating fluid a nonlinear shock wave generation can be observed. For both examples a good agreement between numerical simulation and experimental data has been achieved.

Simkovics, Reinhard; Landes, Hermann; Kaltenbacher, Manfred; Hoffelner, Johann; Lerch, Reinhard

2000-06-01

428

Causes and implications of colloid and microorganism retention hysteresis.

Experiments were designed to better understand the causes and implications of colloid and microorganism retention hysteresis with transients in solution ionic strength (IS). Saturated packed column experiments were conducted using two sizes of carboxyl modified latex (CML) microspheres (0.1 and 1.1 ?m) and microorganisms (coliphage ?X174 and E. coli D21g) under various transient solution chemistry conditions, and 360 ?m Ottawa sand that was subject to different levels of cleaning, namely, a salt cleaning procedure that removed clay particles, and a salt+acid cleaning procedure that removed clay and reduced microscopic heterogeneities due to metal oxides and surface roughness. Comparison of results from the salt and salt+acid treated sand indicated that microscopic heterogeneity was a major contributor to colloid retention hysteresis. The influence of this heterogeneity increased with IS and decreasing colloid/microbe size on salt treated sand. These trends were not consistent with calculated mean interaction energies (the secondary minima), but could be explained by the size of the electrostatic zone of influence (ZOI) near microscopic heterogeneities. In particular, the depth of local minima in the interaction energy has been predicted to increase with a decrease in the ZOI when the colloid size and/or the Debye length decreased (IS increased). The adhesive interaction was therefore largely irreversible for smaller sized 0.1 ?m CML colloids, whereas it was reversible for larger 1.1 ?m CML colloids. Similarly, the larger E. coli D21g exhibited greater reversibility in retention than ?X174. However, direct comparison of CML colloids and microbes was not possible due to differences in size, shape, and surface properties. Retention and release behavior of CML colloids on salt+acid treated sand was much more consistent with mean interaction energies due to reduction in microscopic heterogeneities. PMID:22820488

Bradford, Scott A; Kim, Hyunjung

2012-09-01

429

NSDL National Science Digital Library

The Show-Me Center, located at the University of Missouri, is a math education project of the National Science Foundation. The center's Web site "provides information and resources needed to support selection and implementation of standards-based middle grades mathematic curricula." There are some sample lesson plans offered, but most of the material is solely for use by teachers. Five different middle grade math curriculums were started in 1992, and now, the implementation and results of each curriculum are presented on this site. Teachers can examine each one, view video clips, and read case studies and other reports to choose which parts of the curriculums would fit best into their own classes.

430

Modeling of quasistatic magnetic hysteresis with feed-forward neural networks

NASA Astrophysics Data System (ADS)

A modeling technique for rate-independent (quasistatic) scalar magnetic hysteresis is presented, using neural networks. Based on the theory of dynamic systems and the wiping-out and congruency properties of the classical scalar Preisach hysteresis model, the choice of a feed-forward neural network model is motivated. The neural network input parameters at each time step are the corresponding magnetic field strength and memory state, thereby assuring accurate prediction of the change of magnetic induction. For rate-independent hysteresis, the current memory state can be determined by the last extreme magnetic field strength and induction values, kept in memory. The choice of a network training set is motivated and the performance of the network is illustrated for a test set not used during training. Very accurate prediction of both major and minor hysteresis loops is observed, proving that the neural network technique is suitable for hysteresis modeling.

Makaveev, Dimitre; Dupré, Luc; de Wulf, Marc; Melkebeek, Jan

2001-06-01

431

Effect of surface texturing on superoleophobicity, contact angle hysteresis, and "robustness".

Previously, we reported the creation of a fluorosilane (FOTS) modified pillar array silicon surface comprising ~3-?m-diameter pillars (6 ?m pitch with ~7 ?m height) that is both superhydrophobic and superoleophobic, with water and hexadecane contact angles exceeding 150° and sliding angles at ~10° owing to the surface fluorination and the re-entrant structure in the side wall of the pillar. In this work, the effects of surface texturing (pillar size, spacing, and height) on wettability, contact angle hysteresis, and "robustness" are investigated. We study the static, advancing, and receding contact angles, as well as the sliding angles as a function of the solid area fraction. The results reveal that pillar size and pillar spacing have very little effect on the static and advancing contact angles, as they are found to be insensitive to the solid area fraction from 0.04 to ~0.4 as the pillar diameter varies from 1 to 5 ?m and the center-to-center spacing varies from 4.5 to 12 ?m. On the other hand, sliding angle, receding contact angle, and contact angle hysteresis are found to be dependent on the solid area fraction. Specifically, receding contact angle decreases and sliding angle and hysteresis increase as the solid area fraction increases. This effect can be attributable to the increase in pinning as the solid area fraction increases. Surface Evolver modeling shows that water wets and pins the pillar surface whereas hexadecane wets the pillar surface and then penetrates into the side wall of the pillar with the contact line pinning underneath the re-entrant structure. Due to the penetration of the hexadecane drop into the pillar structure, the effect on the receding contact angle and hysteresis is larger relative to that of water. This interpretation is supported by studying a series of FOTS pillar array surfaces with varying overhang thickness. With the water drop, the contact line is pinned on the pillar surface and very little overhang thickness effect was observed. On the other hand, the hexadecane drop is shown to wet the pillar surface and the side wall of the overhang. It then pins at the lower edge of the overhang structure. A plot of the thickness of the overhang as a function of the static, advancing, and receding contact angles and sliding angle of hexadecane reveals that static, advancing, and receding contact angles decrease and sliding angle increases as the thickness of the overhang increases. A larger overhang effect is observed with octane due to its lower surface tension. The robustness of the pillar array surface against external pressure induced wetting and abrasion was modeled. Surface Evolver simulation (with the hexadecane drop) indicates that wetting breakthrough pressure as high as ~70 kPa is achievable with 0.5-?m-diameter pillar array FOTS surfaces. Mechanical modeling shows that bending of the pillars is the key failure by abrasion, which can be avoided with a short pillar structure. The path to fabricate a superoleophobic surface that can withstand the external force equivalent of a gentle cleaning blade (up to ~30 kPa) without wetting and abrasion failure is discussed. PMID:22992132

Zhao, Hong; Park, Kyoo-Chul; Law, Kock-Yee

2012-10-23

432

Interpretation of spring recession curves.

Recession curves contain information on storage properties and different types of media such as porous, fractured, cracked lithologies and karst. Recession curve analysis provides a function that quantitatively describes the temporal discharge decay and expresses the drained volume between specific time limits (Hall 1968). This analysis also allows estimating the hydrological significance of the discharge function parameters and the hydrological properties of the aquifer. In this study, we analyze data from perennial springs in the Judean Mountains and from others in the Galilee Mountains, northern Israel. All the springs drain perched carbonate aquifers. Eight of the studied springs discharge from a karst dolomite sequence, whereas one flows out from a fractured, slumped block of chalk. We show that all the recession curves can be well fitted by a function that consists of two exponential terms with exponential coefficients alpha1 and alpha2. These coefficients are approximately constant for each spring, reflecting the hydraulic conductivity of different media through which the ground water flows to the spring. The highest coefficient represents the fast flow, probably through cracks, or quickflow, whereas the lower one reflects the slow flow through the porous medium, or baseflow. The comparison of recession curves from different springs and different years leads to the conclusion that the main factors that affect the recession curve exponential coefficients are the aquifer lithology and the geometry of the water conduits therein. In normal years of rainy winter and dry summer, alpha1 is constant in time. However, when the dry period is longer than usual because of a dry winter, alpha1 slightly decreases with time. PMID:12236268

Amit, H; Lyakhovsk, V; Katz, A; Starinsky, A; Burg, A

2002-01-01

433

Ensembles of networks are used as null models in many applications. However, simple null models often show much less clustering than their real-world counterparts. In this paper, we study a "biased rewiring model" where clustering is enhanced by means of a fugacity as in the Strauss (or "triangle") model, but where the number of links attached to each node is strictly preserved. Similar models have been proposed previously in Milo [Science 298, 824 (2002)]. Our model exhibits phase transitions as the fugacity is changed. For regular graphs (identical degrees for all nodes) with degree k>2 we find a single first order transition. For all nonregular networks that we studied (including Erdös-Rényi, scale-free, and several real-world networks) multiple jumps resembling first order transitions appear. The jumps coincide with the sudden emergence of "cluster cores:" groups of highly interconnected nodes with higher than average degrees, where each edge participates in many triangles. Hence, clustering is not smoothly distributed throughout the network. Once formed, the cluster cores are difficult to remove, leading to strong hysteresis. To study the cluster cores visually, we introduce q-clique adjacency plots. Cluster cores constitute robust communities that emerge spontaneously from the triangle generating process, rather than being put explicitly into the definition of the model. All the quantities we measured including the modularity, assortativity, clustering and number of four and five-cliques exhibit simultaneous jumps and are equivalent order parameters. Finally, we point out that cluster cores produce pitfalls when using the present (and similar) models as null models for strongly clustered networks, due to strong hysteresis which leads to broken ergodicity on realistic sampling time scales. PMID:20481794

Foster, David; Foster, Jacob; Paczuski, Maya; Grassberger, Peter

2010-04-01

434

NASA Astrophysics Data System (ADS)

The results of the light curves analysis of 234 meteors observed and recorded within the double-station image intensifier observations at the Ond?ejov observatory are presented. Double-station observations allow to compute the meteor trajectory in the solar system and in the atmosphere as well as to determinate the absolute magnitude of meteor and its mass. Light curves and heights data of all major meteor showers - Lyrids, ?-Aquarids, Perseids, Orionids, Leonids, Geminids as well as many sporadic meteors - were analysed. The differences between individual showers were found, e.g. Perseids appear to be more compact than Leonids. There is also difference between 1998 and 1999 Leonids. This suggests different composition or structure of parent bodies. Our data show that the beginning heights of Perseids, Orionids and Leonids are weakly dependent on meteor mass, although the dust-ball theory assumes they should be mass independent.

Koten, Pavel; Borovi?ka, Ji?í

2001-11-01

435

Stochastic growth phenomena on curved interfaces are studied by means of stochastic partial differential equations. These are derived as counterparts of linear planar equations on a curved geometry after a reparametrization invariance principle has been applied. We examine differences and similarities with the classical planar equations. Some characteristic features are the loss of correlation through time and a particular behavior of the average fluctuations. Dependence on the metric is also explored. The diffusive model that propagates correlations ballistically in the planar situation is particularly interesting, as this propagation becomes nonuniversal in the new regime.

Escudero, Carlos [Instituto de Ciencias Matematicas, Consejo Superior de Investigaciones Cientificas, C/ Serrano 123, 28006 Madrid (Spain)], E-mail: cel@imaff.cfmac.csic.es

2009-08-15

436

NSDL National Science Digital Library

Calculus texts have problems on finding the Areas between Curves in the chapters on applications of Integration. The NCB suggests finding some of these examples in a text and trying them in Harumi's graph. Experimenting on a computer with the approximation for finding the area using rectangles is fascinating. As the number of rectangles increases, the approximation improves. Therefore, mathematicians define the area A between the two curves as the limit of the sum of the areas of these approximating rectangles where n is the number of rectangles bounded between a and b.

Monroy, Harumi

2006-01-01

437

NASA Astrophysics Data System (ADS)

Smart actuators, such as shape memory alloy (SMA) and magnetostrictive actuators, exhibit saturation nonlinearity and hysteresis that may be symmetric or asymmetric. The Prandtl-Ishlinskii model employing classical play operators has been used to describe the hysteresis properties of smart actuators that are symmetric in nature. In this study, the application of a generalized play operator capable of characterizing symmetric as well as asymmetric hysteresis properties with output saturation is explored in formulating a generalized Prandtl-Ishlinskii model. The generalized play operator employs different envelope functions under increasing and decreasing inputs to describe asymmetric and saturated output-input hysteresis loops. The validity of the proposed generalized model to characterize symmetric and asymmetric hysteresis properties is demonstrated by comparing the model responses with the measured major and minor hysteresis loops of three different types of actuator, namely SMA, magnetostrictive, and piezoceramic actuators. The simulation results suggest that the proposed generalized Prandtl-Ishlinskii model can be directly applied for modeling the hysteresis loops of different smart actuators together with the output saturation.

Janaideh, Mohammad Al; Rakheja, Subhash; Su, Chun-Yi

2009-04-01

438

Research on the dynamic hysteresis loop model of the residence times difference (RTD)-fluxgate.

Based on the core hysteresis features, the RTD-fluxgate core, while working, is repeatedly saturated with excitation field. When the fluxgate simulates, the accurate characteristic model of the core may provide a precise simulation result. As the shape of the ideal hysteresis loop model is fixed, it cannot accurately reflect the actual dynamic changing rules of the hysteresis loop. In order to improve the fluxgate simulation accuracy, a dynamic hysteresis loop model containing the parameters which have actual physical meanings is proposed based on the changing rule of the permeability parameter when the fluxgate is working. Compared with the ideal hysteresis loop model, this model has considered the dynamic features of the hysteresis loop, which makes the simulation results closer to the actual output. In addition, other hysteresis loops of different magnetic materials can be explained utilizing the described model for an example of amorphous magnetic material in this manuscript. The model has been validated by the output response comparison between experiment results and fitting results using the model. PMID:24002230

Wang, Yanzhang; Wu, Shujun; Zhou, Zhijian; Cheng, Defu; Pang, Na; Wan, Yunxia

2013-01-01

439

The effect of contact angle hysteresis on droplet motion and collisions on superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

The effect of varying the contact angle hysteresis of a superhydrophobic surface on the characteristics and dynamics of water droplet motion and their subsequent collision are investigated using a high-speed camera. The surfaces are created by imparting random roughness to Teflon through sanding. With this technique, it is possible to create surfaces with similar advancing contact angles near 150 degrees, but with varying contact angle hysteresis. This talk will focus on a number of interesting experimental observations pertaining to drop dynamics along a surface with uniform hysteresis, drop motion along surfaces with transition zones from one hysteresis to another, and the collision of droplets on surfaces of uniform hysteresis. For single drop studies, gravity is used as the driving force, while the collision studies use pressurized air to propel one drop into the other. For the case of droplet collision, the effect of hysteresis, Weber number, and impact number on the maximum deformation of the drops, and the post-collision dynamics will be discussed. For the single droplet measurements, the resistance to motion will be characterized as well as the transition from rolling to sliding as a function of drop size, inclination angle, and hysteresis. Additionally, we will quantify the effect of surface transitions on the resulting motion, mixing, and deflection of the drops.

Nilsson, Michael; Rothstein, Jonathan

2010-11-01

440

Research on the Dynamic Hysteresis Loop Model of the Residence Times Difference (RTD)-Fluxgate

Based on the core hysteresis features, the RTD-fluxgate core, while working, is repeatedly saturated with excitation field. When the fluxgate simulates, the accurate characteristic model of the core may provide a precise simulation result. As the shape of the ideal hysteresis loop model is fixed, it cannot accurately reflect the actual dynamic changing rules of the hysteresis loop. In order to improve the fluxgate simulation accuracy, a dynamic hysteresis loop model containing the parameters which have actual physical meanings is proposed based on the changing rule of the permeability parameter when the fluxgate is working. Compared with the ideal hysteresis loop model, this model has considered the dynamic features of the hysteresis loop, which makes the simulation results closer to the actual output. In addition, other hysteresis loops of different magnetic materials can be explained utilizing the described model for an example of amorphous magnetic material in this manuscript. The model has been validated by the output response comparison between experiment results and fitting results using the model.

Wang, Yanzhang; Wu, Shujun; Zhou, Zhijian; Cheng, Defu; Pang, Na; Wan, Yunxia

2013-01-01

441

NASA Astrophysics Data System (ADS)

Numerical calculations based on the Navier-Stokes equations are carried out to investigate the reflection of shock waves over straight reflecting surfaces in steady flows. The results for a flow Mach number of M0=4.96 confirm the recent experimental findings of Chpoun et al. (1995) concerning the transition from regular to Mach reflection. Numerical calculations as well as experimental results show a hysteresis phenomenon during this transition and the regular reflection is found to be stable in the dual-solution domain in which theoretically both regular and Mach reflection wave configurations are possible.

Chpoun, A.; Ben-Dor, G.

1995-12-01

442

Magnetic hysteresis and compensation behaviors in spin-1 bilayer Ising model

NASA Astrophysics Data System (ADS)

The hysteresis and compensation behaviors of spin-1 bilayer Ising model on a square lattice is studied within the framework of the effective-field theory with correlation. The effects of Hamiltonian parameters on hysteresis behaviors are discussed in detail. We also obtained the Q-, R-, P-, S- and L-type compensation behaviors in the system. A number of interesting phenomena such as the shape of the hysteresis loops and compensation types have been found. The obtained results are compared with some experimental and theoretical results and found to be in a qualitatively good agreement.

Kantar, Ersin; Erta?, Mehmet

2014-06-01

443

Effects of annealing, pre-tension and mounting on the hysteresis of polymer strain sensors

NASA Astrophysics Data System (ADS)

When exposed to high levels of strain, polymer optical fibre grating sensors recorded in poly(methyl methacrylate) based fibre often exhibit hysteresis in the response of their Bragg wavelength to strain. We demonstrate that the application of pre-tension and annealing of the polymer fibre can reduce this hysteresis when the fibre is suspended freely between two supports, but much better performance is obtained when the sensor is attached directly to a substrate. In this case, the hysteresis can be lessened by more than a factor of 12.

Abang, Ada; Webb, David J.

2014-01-01

444

National Technical Information Service (NTIS)

The invention is a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap...

R. C. Davis T. T. Bales D. M. K. Royster L. R. Jackson

1983-01-01

445

ERIC Educational Resources Information Center

The transformation of a solid to its net is based on something quite different from simple perceptual impression. It is a mental operation performed by manipulating mental images. The aim of this study was to observe pre-service and in-service teachers' ability to visualize the transformation of a curved solid to its net and vice versa, and to try…

Cohen, Nitsa

2003-01-01

446

ERIC Educational Resources Information Center

Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

Lawes, Jonathan F.

2013-01-01

447

Electrostatic curved electrode actuators

This paper presents the design and performance of an electrostatic actuator consisting of a laterally compliant cantilever beam and a fixed curved electrode, both suspended above a ground plane. A theoretical description of the static behavior of the cantilever as it is pulled into contact with the rigid fixed-electrode structure is given. Two models are presented: a simplified semi-analytical model

Rob Legtenberg; John Gilbert; Stephen D. Senturia; Miko Elwenspoek

1997-01-01

448

Straightening Out Learning Curves

ERIC Educational Resources Information Center

The basic mathematical theory behind learning curves is explained, together with implications for clerical and industrial training, evaluation of skill development, and prediction of future performance. Brief studies of textile worker and typist training are presented to illustrate such concepts as the reduction fraction (a consistent decrease in…

Corlett, E. N.; Morecombe, V. J.

1970-01-01

449

Elliptic Curve Cryptography Engineering

In recent years, elliptic curve cryptography (ECC) has gained widespread exposure and acceptance, and has already been included in many security standards. Engineering of ECC is a complex, interdisciplinary research field encompassing such fields as mathematics, computer science, and electrical engineering. In this paper, we survey ECC implementation issues as a prominent case study for the relatively new discipline of

ALESSANDRO CILARDO; LUIGI COPPOLINO; NICOLA MAZZOCCA; LUIGI ROMANO

2006-01-01

450

Characteristic Curves of PEMFC

NSDL National Science Digital Library

This in-class exercise will allow students hands-on experience working with a proton exchange membrane fuel cell, or PEMFC. The class will examine the characteristic curve of one of these fuel cells and measure the voltage and current output of the cell. Step by step instructions are provided for the experiment. This document may be downloaded in PDF file format.

2012-07-11

451

ERIC Educational Resources Information Center

Graphic tips for using the Geometer's Sketchpad (GSP) are described. The methods to import an image into GSP, define a coordinate system, plot points and curve fit the function using a graphical calculator are demonstrated where the graphic features of GSP allow teachers to expand the use of the technology application beyond the classroom.

Harper, Suzanne R.; Driskell, Shannon

2005-01-01

452

NSDL National Science Digital Library

In this activity, students will observe the surface of rotating potatoes to help them understand how astronomers can sometimes determine the shape of asteroids from variations in reflective brightness. When astronomers graph data relating to reflective brightness as a function of time, the resulting graph is called a "light curve."

2009-04-22

453

ERIC Educational Resources Information Center

A model based on latent trait theory, with maximum likelihood parameter estimates and associated asymptotic tests, is presented. Latent curve analysis is a method for representing development and is an alternative to repeated measures analysis of variance and first-order auto-regressive models. (SLD)

Meredith, William; Tisak, John

1990-01-01

454

Uncertainty propagation: Curve fitting

NSDL National Science Digital Library

Students will learn a sample-variance curve fitting method that can be used to determine whether a set of experimental data appears to have been generated by a model. This method is based on minimizing the reduced chi-squared value. This video includes a reminder to inspect normalized residuals before reporting fitted parameters.

Liao, David

455

Illumination from curved reflectors

A technique is presented to compute the refkted illumination from curved mirror surfaces onto other surfaces. In accordance with Fermat's principle, this is equivalent to fiiding extremal paths from the light source to the visible surface via the mirrors. Once pathways of illumination are found, h-radiance is computed from the Gaussian curvature of the geometrical wavefront. Tech- niques from optics,

Don P. Mitchell; Pat Hanrahan

1992-01-01

456

Solute concentration-dependent contact angle hysteresis and evaporation stains.

The presence of nonvolatile solutes in a liquid drop on a solid surface can affect the wetting properties. Depending on the surface-activity of the solutes, the extent of contact angle hysteresis (CAH) can vary with their concentration and the pattern of the evaporation stain is altered accordingly. In this work, four types of concentration-dependent CAH and evaporation stains are identified for a water drop containing polymeric additives on polycarbonate. For polymers without surface-activity such as dextran, advancing and receding contact angles (?a and ?r) are independent of solute concentrations, and a concentrated stain is observed in the vicinity of the drop center after complete evaporation. For polymers with weak surface-activity such as poly(ethylene glycol) (PEG), both ?a and ?r are decreased by solute addition, and the stain pattern varies with increasing PEG concentration, including a concentrated stain and a mountain-like island. For polymers with intermediate surface-activity such as sodium polystyrenesulfonate (NaPSS), ?a descends slightly, but ?r decreases significantly after the addition of a substantial amount of NaPSS, and a ring-like stain pattern is observed. Moreover, the size of the ring stain can be controlled by NaPSS concentration. For polymers with strong surface-activity such as poly(vinylpyrrolidone) (PVP), ?a remains essentially a constant, but ?r is significantly lowered after the addition of a small amount of PVP, and the typical ring-like stain is seen. PMID:24933206

Li, Yueh-Feng; Sheng, Yu-Jane; Tsao, Heng-Kwong

2014-07-01

457

Discontinuous Double Power Law Scaling of Magnetic Hysteresis

NASA Astrophysics Data System (ADS)

Frequency(?), applied field(H), and temperature(T) -dependent hysteresis loops of ultrathin Fe films on flat and stepped W(001) surface are measured using the magneto-optic Kerr effect. Power law scaling of the loop area A ~ H^??^? is observed over five decades in ? with exponents similar to those observed for Fe on W(110)^1. In cases where the dynamic coercivity H_c(?) exceeds the applied field, an abrupt collapse of the loop occurs leading to a double-power-law scaling behavior similar to that reported by Luse and Zangwill^2 based on a periodically driven kinetic Ising model. The exponent ?' describing the abrupt loop collapse above the amplitude dependent critical frequency is very large compared to the low frequency range value ?, and ?' is much more sensitive to film thickness than the low frequency regime ?. Supported by DMR-9623494 ^1 Jih-Shin Suen and J. L. Erskine, Bull. Am. Phys. Soc. 41, B22 7 (1996) (and submitted to PRL) ^2 C. N. Luse and A. Zangwill, Phys. Rev. E50, 224 (1994)

Suen, Jih-Shin; Erskine, J. L.

1997-03-01

458

On growth rate hysteresis and catastrophic crystal growth

NASA Astrophysics Data System (ADS)

Different crystal growth rates as supersaturation is increasing or decreasing in impure media is a phenomenon called growth rate hysteresis (GRH) that has been observed in varied systems and applications, such as protein crystallization or during biomineralization. We have recently shown that the transient adsorption of impurities onto newly formed active sites for growth (or kinks) is sensitive to the direction and rate of supersaturation variation, thus providing a possible explanation for GRH [6]. In the present contribution, we expand on this concept by deriving the analytical expressions for transient crystal growth based on the energetics of growth hillock formation and kink occupation by impurities. Two types of GRH results are described according to the variation of kink density with supersaturation: for nearly constant density, decreasing or increasing supersaturation induce, respectively, growth promoting or inhibiting effects relative to equilibrium conditions. This is the type of GRH measured by us during the crystallization of egg-white lysozyme. For variable kink density, slight changes in the supersaturation level may induce abrupt variations in the crystal growth rate. Different literature examples of this so-called 'catastrophic' crystal growth are discussed in terms of their fundamental consequences.

Ferreira, Cecília; Rocha, Fernando A.; Damas, Ana M.; Martins, Pedro M.

2013-04-01

459

Hysteresis in a swirling jet as a model tornado

NASA Astrophysics Data System (ADS)

A swirling jet, emerging normal to a plane, serves as a model of a tornado and is characterized by its flow force and outer circulation. This model is examined here using the full Navier-Stokes equations. Three branches of solutions are found which form a hysteresis loop and a cusp catastrophe that means jump transitions between flow regimes. One of the jumps relates to vortex breakdown and the other relates to a new (opposite) effect: abrupt vortex consolidation. These results are compared with those of Long (1961), who considered a near-axis jet in the boundary layer approximation. More detailed analysis made here for high circulation values allows discovery of two new types of asymptotic solutions corresponding to a near-plane fan jet and a two-cell flow. It was also found that the boundary layer approach for the near-axis jet fails to accurately yield the total flow force because the outer flow contributes a share of the momentum flux of comparable magnitude to that of the inner flow. The prediction of the jump transitions between one- and two-cell flow patterns agrees with observations of abrupt changes in tornado patterns in nature.

Shtern, V.; Hussain, F.

1993-09-01

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Droplet evaporation dynamics on a superhydrophobic surface with negligible hysteresis.

We report on experiments of droplet evaporation on a structured superhydrophobic surface that displays very high contact angle (CA ? 160 deg), and negligible contact angle hysteresis (<1 deg). The droplet evaporation is observed to occur in a constant-contact-angle mode, with contact radius shrinking for almost the entire duration of evaporation. Experiments conducted on Teflon-coated smooth surface (CA ? 120 deg) as a baseline also support an evaporation process that is dominated by a constant-contact-angle mode. The experimental results are compared with an isothermal diffusion model for droplet evaporation from the literature. Good agreement is observed for the Teflon-coated smooth surface between the analytical expression and experimental results in terms of the total time for evaporation, transient volume, contact angle, and contact radius. However, for the structured superhydrophobic surface, the experiments indicate that the time taken for complete evaporation of the droplet is greater than the predicted time, across all droplet volumes. This disparity is attributed primarily to the evaporative cooling at the droplet interface due to the high aspect ratio of the droplet and also the lower effective thermal conductivity of the substrate due to the presence of air gaps. This hypothesis is verified by numerically evaluating the temperature distribution along the droplet interface. We propose a generalized relation for predicting the instantaneous volume of droplets with initial CA > 90 deg, irrespective of the mode of evaporation. PMID:23952149

Dash, Susmita; Garimella, Suresh V

2013-08-27