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1

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

2

The Unsymmetrical Hysteresis Loop  

Microsoft Academic Search

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

3

Hysteresis-Loop Overskewing  

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

4

A theory of DE hysteresis loop  

Microsoft Academic Search

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

5

Analysis of wasp-waisted hysteresis loops in magnetic rocks.  

PubMed

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

6

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

7

Lumped-circuit models for nonlinear inductors exhibiting hysteresis loops  

Microsoft Academic Search

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

8

Sensorless evaluation of asymmetric hysteresis loops of ferromagnetic materials  

Microsoft Academic Search

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

9

Minor Hysteresis Loop in Fe Metal and Alloys  

Microsoft Academic Search

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

10

Understanding the hysteresis loop conundrum in pharmacokinetic / pharmacodynamic relationships.  

PubMed

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

11

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

12

Domain Nucleation and Hysteresis Loop Shape in Piezoresponse Force Spectroscopy  

SciTech Connect

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

13

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

14

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

Microsoft Academic Search

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

15

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

Microsoft Academic Search

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

16

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

17

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

18

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

19

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

SciTech Connect

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

20

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

21

Reduction of major and minor hysteresis loops in a piezoelectric actuator  

Microsoft Academic Search

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

22

Temperature-electric field hysteresis loop of electrocaloric effect in ferroelectricity--Direct measurement and analysis of electrocaloric effect. I  

NASA Astrophysics Data System (ADS)

The polarization of polar domain in ferroelectric materials is orientated and reversed with the alternating electric field, and the hysteresis loops of polarization-electric field (P-E) and strain-electric field (S-E) are observed. For electrocaloric (EC) effect, the temperature change with the application and removal of electric field is also attributed to the change of polarization with the applied field. In most reports about EC, the temperature change is shown as an abrupt jump or slump due to the applied electric field that is a pulsed wave. Obviously, it is impossible to observe the hysteresis loop of EC. In our research, both sine wave and pulsed wave electric field are applied to samples in direct measurement, and temperature-electric field hysteresis loop (T-E) is observed only in measurement of sine wave. The T-E hysteresis loop displays a shape of butterfly, just like the shape of S-E. The electric field dependence of EC is also given. The obtained results will be helpful for us to know the electrocaloric effect further.

Wang, Jinfei; Yang, Tongqing; Wei, Kun; Yao, Xi

2013-04-01

23

Cumulative growth of minor hysteresis loops in the Kolmogorov model  

SciTech Connect

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

24

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

Microsoft Academic Search

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

25

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

Microsoft Academic Search

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

26

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

Microsoft Academic Search

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

27

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

28

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

PubMed

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

29

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

PubMed Central

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

30

Nondestructive characterization of recovery and recrystallization in cold rolled low carbon steel by magnetic hysteresis loops  

Microsoft Academic Search

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

31

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

National Technical Information Service (NTIS)

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 confi...

J. Alam L. Berke P. L. N. Murthy

1993-01-01

32

Ac hysteresis loop measurement of stator-tooth in induction motor  

SciTech Connect

The properties of ac hysteresis loop of a stator tooth in a 5 hp induction motor was measured and analyzed. The load increase on the motor decreased magnetic induction, however increase the minor hysteresis loops in the high induction region. This effect caused increase in the core loss. Depending on condition of the motor, the core loss of the stator tooth can be 50% greater than the core loss under sinusoidal magnetic induction waveform.

Son, D.

1999-09-01

33

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

34

A macroscopic theory for the existence of the hysteresis and butterfly loops in ferroelectricity  

Microsoft Academic Search

We present in this paper a minimal macroscopic theory leading to the hysteresis loop and the butterfly loop in ferroelectricity. This theory is based on the notion that as domains switch under the action of an external electric field the number of dipoles aligned in the direction of the field also alters and it obeys a rate law which depends

Peter J. Chen; Stephen T. Montgomery

1980-01-01

35

The effects of stress on a ferromagnet on a minor hysteresis loop  

Microsoft Academic Search

Reversible and irreversible changes in magnetization due to stress on a minor hysteresis loop were studied at various magnetic field strengths. It was found that the irreversible changes were not always directed toward the principal anhysteretic, contrary to Jiles and Atherton's hypothesis (1986). Also, two different demagnetization methods were used within the minor loop to test the existence of postulated

DAVID L. ATHERTON; V. Ton

1990-01-01

36

Triangular hysteresis loops in the spin-rotation region of orthoferrites  

NASA Astrophysics Data System (ADS)

A theory is proposed that qualitatively explains the shapes of the hysteresis loops in orthoferrites within the temperature interval of the magnetic reorientation transition. Triangular loops result from the strong temperature dependence of both the magnetic moment and the magnetic domain wall structure.

Bazaliy, Ya. B.; Tsymbal, L. T.

2010-08-01

37

Study of the fast photoswitching of spin crossover nanoparticles outside and inside their thermal hysteresis loop  

SciTech Connect

We have studied the low spin to high spin phase transition induced by nanosecond laser pulses outside and within the thermal hysteresis loop of the [Fe(Htrz){sub 2} trz](BF{sub 4}){sub 2}-H{sub 2}O spin crossover nanoparticles. We demonstrate that, whatever the temperature of the compound, the photo-switching is achieved in less than 12.5 ns. Outside the hysteresis loop, the photo-induced high spin state remains up to 100 {mu}s and then relaxes. Within the thermal hysteresis loop, the photo-induced high spin state remains as long as the temperature of the sample is kept within the thermal loop. A Raman study indicates that the photo-switching can be completed using single laser pulse excitation.

Galle, G.; Degert, J.; Freysz, E. [Universite de Bordeaux, LOMA, UMR-CNRS 5798, 351 cours de la Liberation, 33405 Talence Cedex (France)] [Universite de Bordeaux, LOMA, UMR-CNRS 5798, 351 cours de la Liberation, 33405 Talence Cedex (France); Etrillard, C.; Letard, J.-F. [CNRS, Universite de Bordeaux, ICMCB, UPR CNRS 9048, 87 Avenue du Docteur Albert Schweitzer, 33608 Pessac Cedex (France)] [CNRS, Universite de Bordeaux, ICMCB, UPR CNRS 9048, 87 Avenue du Docteur Albert Schweitzer, 33608 Pessac Cedex (France); Guillaume, F. [Universite de Bordeaux, ISM, UMR CNRS 5255, 351 cours de la Liberation, 33405 Talence Cedex (France)] [Universite de Bordeaux, ISM, UMR CNRS 5255, 351 cours de la Liberation, 33405 Talence Cedex (France)

2013-02-11

38

Study of the fast photoswitching of spin crossover nanoparticles outside and inside their thermal hysteresis loop  

NASA Astrophysics Data System (ADS)

We have studied the low spin to high spin phase transition induced by nanosecond laser pulses outside and within the thermal hysteresis loop of the [Fe(Htrz)2 trz](BF4)2-H2O spin crossover nanoparticles. We demonstrate that, whatever the temperature of the compound, the photo-switching is achieved in less than 12.5 ns. Outside the hysteresis loop, the photo-induced high spin state remains up to 100 ?s and then relaxes. Within the thermal hysteresis loop, the photo-induced high spin state remains as long as the temperature of the sample is kept within the thermal loop. A Raman study indicates that the photo-switching can be completed using single laser pulse excitation.

Gallé, G.; Etrillard, C.; Degert, J.; Guillaume, F.; Létard, J.-F.; Freysz, E.

2013-02-01

39

Variation of the hysteresis loop with the Bouc–Wen model parameters  

Microsoft Academic Search

The Bouc–Wen model for smooth hysteresis has received an increasing interest in the last few years due to the ease of its\\u000a numerical implementation and its ability to represent a wide range of hysteresis loop shapes. This model consists of a first-order\\u000a nonlinear differential equation that contains some parameters that can be chosen, using identification procedures, to approximate\\u000a the behavior

Fayçal Ikhouane; Jorge E. Hurtado; José Rodellar

2007-01-01

40

Domain Dynamics in Piezoresponse Force Spectroscopy: Quantitative Deconvolution and Hysteresis Loop Fine Structure  

SciTech Connect

Domain dynamics in the Piezoresponse Force Spectroscopy (PFS) experiment is studied using the combination of local hysteresis loop acquisition with simultaneous domain imaging. The analytical theory for PFS signal from domain of arbitrary cross-section and length is developed for the analysis of experimental data on Pb(Zr,Ti)O3 polycrystalline films. The results suggest formation of oblate domain at early stage of the nucleation and growth, consistent with efficient screening of depolarization field. The fine structure of the hysteresis loop is shown to be related to the observed jumps in the domain geometry during domain wall propagation (nanoscale Barkhausen jumps), indicative of strong domain-defect interactions.

Bdikin, Igor [University of Aveiro, Portugal; Kholkin, Andrei [University of Aveiro, Portugal; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Svechnikov, S. V. [National Academy of Science of Ukraine, Kiev, Ukraine; Kim, S.-H. [INOSTEK Inc., Gyeonggi, Korea; Kalinin, Sergei V [ORNL

2008-01-01

41

Investigation of the Temperature Hysteresis Phenomenon of a Loop Heat Pipe  

NASA Technical Reports Server (NTRS)

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 the power variation. The temperature hysteresis could impose limitations on the LHP applications since the LHP may exhibit different steady-state operating temperatures at a given power input even when the condenser sink temperature remains unchanged. In order to obtain insight to this phenomenon, a LHP was tested at different elevations and tilts by using an elaborated power profile. A hypothesis was suggested to explain the temperature hysteresis. This hypothesis explains well the experimental observations. Results of this study provide a better understanding of the performance characteristics of the LHPS.

Kaya, Tarik; Ku, Jentung; Hoang, Triem; Cheung, Mark K.

1999-01-01

42

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

43

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

PubMed

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

44

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

45

Constitutive model of shape memory alloys for unidirectional loading considering inner hysteresis loops  

Microsoft Academic Search

A specimen-based macroscopic constitutive model of shape memory alloys for unidirectional loading, which is simple yet accurate and has a physical background, was derived from a grain-based microscopic model. To consider the inner hysteresis loops of a stress-strain-temperature relationship, a new inner loop model called the shift and skip model was proposed. This model is based on microscopic aspects and

Tadashige Ikeda; Florin Andrei Nae; Hisashi Naito; Yuji Matsuzaki

2004-01-01

46

The influence of the shape of domains on the ferroelectric hysteresis loop  

Microsoft Academic Search

Simple models of the polarization reversal in ferroelectrics with domains in the shape of either circular cylinders or parallel strips, which grow only by sideways expansion, are used to calculate the hysteresis loops and particularly the coercive field as a function of the amplitude and frequency of a sinusoidal electric field. The small differences in results corresponding to various models

Jiri Janta

1971-01-01

47

Thermomechanical modeling of polycrystalline SMAs under cyclic loading, Part IV: modeling of minor hysteresis loops  

Microsoft Academic Search

A thermomechanical model for the hysteretic response of Shape Memory Alloys (SMAs) is proposed in this paper by expanding a previous model developed by Bo and Lagoudas (Z. Bo, D.C. Lagoudas, International Journal of Engineering Science, accepted) to include minor hysteresis loops. The constitutive model for SMAs previously developed by Bo and Lagoudas is reviewed first, and a simplification for

Zhonghe Bo; Dimitris C. Lagoudas

1999-01-01

48

Hysteresis Loop for a No-loaded, Delta-connected Transformer Model Deduced from Measurements  

NASA Astrophysics Data System (ADS)

At a transformer's steady-state condition, whereby a transformer and its load are constantly supplied by a sinusoidal source, the current-flux pair within the transformer core and its windings will cycle along a hysteresis loop. This nonlinear current-flux characteristic becomes important while at transformer gets reenergized. A remaining residual flux and the fact that a transformer is typically used up to its saturation level can lead to high-amplitude magnetizing inrush currents and associated voltage disturbances. These disturbances can be reduced by controlled transformer switching. In order to pre-evaluate the effect of a specific controlled transformer energization, pre-simulations can be applied. In that case the hysteresis loop and its saturation characteristic will become the most important model parameter. If the corresponding manufacturer specifications are not available a standard hysteresis loops can be used, but might come up with an inaccurate simulation result. Therefore, this paper analyses the measured 3-phase currents from two delta-connected power transformers by “Fourier Series” in order to deduce a single-phase hysteresis loop, which can be implemented into a typical 3-phase transformer model. Additionally, the saturation behavior of a power-transformer will be estimated and a comparison of ATP/EMTP simulations will conclude this paper.

Corrodi, Yves; Kamei, Kenji; Kohyama, Haruhiko; Ito, Hiroki

49

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

50

Domain Dynamics in Piezoresponse Force Microscopy: Quantitative Deconvolution and Hysteresis Loop Fine Structure  

SciTech Connect

Domain dynamics in the Piezoresponse Force Spectroscopy (PFS) experiment is studied using the combination of local hysteresis loop acquisition with simultaneous domain imaging. The analytical theory for PFS signal from domain of arbitrary cross-section is developed and used for the analysis of experimental data on Pb(Zr,Ti)O3 polycrystalline films. The results suggest formation of oblate domain at early stage of the domain nucleation and growth, consistent with efficient screening of depolarization field within the material. The fine structure of the hysteresis loop is shown to be related to the observed jumps in the domain geometry during domain wall propagation (nanoscale Barkhausen jumps), indicative of strong domain-defect interactions.

Bdikin, Igor [University of Aveiro, Portugal; Kholkin, Andrei [University of Aveiro, Portugal; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Svechnikov, S. V. [National Academy of Science of Ukraine, Kiev, Ukraine; Kim, S.-H. [INOSTEK Inc., Gyeonggi, Korea; Kalinin, Sergei V [ORNL

2008-01-01

51

Pinholes in antiferromagnetically coupled multilayers: Effects on hysteresis loops and relation to biquadratic exchange  

Microsoft Academic Search

We present a micromagnetic study of the influence of ferromagnetic bridges between consecutive ferromagnetic layers in antiferromagnetically coupled multilayers. The model is compared with experimental results for hysteresis loops obtained from the multilayer systems Co-Cu and FeNi-Ag. The presence of pinholes in Cu-Co multilayers is confirmed by transmission electron microscopy. We demonstrate that low densities of ferromagnetic pinholes in such

J. F. Bobo; H. Kikuchi; O. Redon; E. Snoeck; M. Piecuch; R. L. White

1999-01-01

52

A Theory of DE Hysteresis Loop Based on the Avrami Model  

Microsoft Academic Search

The D-E hysteresis loop of ferroelectrics is theoretically studied on the basis of the extended Avrami theory. If the sideway velocity depends only on the instant value of the applied field, the volume fraction of the reversed area is expressed as q(E)=1-exp (-f-dPhi(E)), where f and d are, respectively, the frequency of the applied field and the growth dimension of

Hiroshi Orihara; Shigeharu Hashimoto; Yoshihiro Ishibashi

1994-01-01

53

Hysteresis Loop for a No-loaded, Delta-connected Transformer Model Deduced from Measurements  

Microsoft Academic Search

At a transformer's steady-state condition, whereby a transformer and its load are constantly supplied by a sinusoidal source, the current-flux pair within the transformer core and its windings will cycle along a hysteresis loop. This nonlinear current-flux characteristic becomes important while at transformer gets reenergized. A remaining residual flux and the fact that a transformer is typically used up to

Yves Corrodi; Kenji Kamei; Haruhiko Kohyama; Hiroki Ito

2010-01-01

54

ac Dynamics of Ferroelectric Domains from an Investigation of the Frequency Dependence of Hysteresis Loops  

SciTech Connect

We investigated nonequilibrium domain wall dynamics under an ac field by measuring the hystere- sis loops of epitaxial ferroelectric capacitors at various frequencies and temperatures. Polarization switching is induced mostly by thermally activated creep motion at lower frequencies, and by vis- cous ow motion at higher frequencies. The dynamic crossover between the creep and ow regimes unveils two frequency-dependent scaling regions of hysteresis loops. Based on these findings, we constructed a dynamic phase diagram for hysteretic ferroelectric domain dynamics in the presence of ac fields.

Yang, Sang Mo [Seoul National University; Jo, Ji Young [Seoul National University; Kim, T. H. [Seoul National University; Yoon, J. -G. [University of Suwon; Song, T. K. [Changwon National University; Lee, Ho Nyung [ORNL; Marton, Zsolt [ORNL; Park, S. [Korea Basic Science Institute, Korea; Jo, Y. [Korea Basic Science Institute, Korea; Noh, Tae Won [Seoul National University

2010-01-01

55

Defect-induced asymmetry of local hysteresis loops on BiFeO3 surfaces  

SciTech Connect

Local piezoresponse hysteresis loops were systematically studied on the surface of ferroelectric thin films of BiFeO{sub 3} grown on SrRuO{sub 3} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3} electrodes and compared between ultrahigh vacuum and ambient environment. The loops on all the samples exhibited characteristic asymmetry manifested in the difference of the piezoresponse slope following local domain nucleation. Spatially resolved mapping has revealed that the asymmetry is strongly correlated with the random-field disorder inherent in the films and is not affected by the random-bond disorder component. The asymmetry thus originates from electrostatic disorder within the film, which allows using it as a unique signature of single defects or defect clusters. The electrostatic effects due to the measurement environment also contribute to the total asymmetry of the piezoresponse loop, albeit with a much smaller magnitude compared to local defects.

Maksymovych, Petro [ORNL; Balke, Nina [ORNL; Jesse, Stephen [ORNL; Huijben, Mark [University of Twente, Enschede, Netherlands; Ramesh, R. [University of California, Berkeley; Baddorf, Arthur P [ORNL; Kalinin, Sergei V [ORNL

2009-01-01

56

Susceptibility and Inverted Hysteresis Loop of Prussian Blue Analogs with Orthorhombic Structure  

NASA Astrophysics Data System (ADS)

The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in details. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri-ferrimagnet.

Guo, An-Bang; Jiang, Wei

2012-11-01

57

Transformations of magnetic mineralogy in rocks revealed by difference of hysteresis loops measured after stepwise heating: theory and case studies  

Microsoft Academic Search

A new approach for tracking mineralogical alterations during laboratory stepwise heating experiments is proposed. It uses the hysteresis loop obtained as a difference between the loops measured after thermal treatment at two different consecutive temperatures. Depending on the nature of the mineralogical alterations (the formation of a new ferrimagnetic phase from a paramagnetic one, the thermal transformation of the originally

Bernard Henry; Diana Jordanova; Neli Jordanova; Maxime Le Goff

2005-01-01

58

Nondestructive indication of plastic deformation of cold-rolled stainless steel by magnetic minor hysteresis loops measurement  

Microsoft Academic Search

Cold-rolled austenitics stainless steel samples were non-destructively characterized by means of sets of magnetic minor hysteresis loops. The flat samples were magnetized by an attached yoke, and reliable parameters were obtained from the series of minor loops, without magnetic saturation of the samples. It was found, that some magnetic quantities, well known to be closely connected to the samples’ structure

G. Vértesy; I. Mészáros; I. Tomáš

2005-01-01

59

Genetic algorithms and neural networks generalizing the Jiles-Atherton model of static hysteresis for dynamic loops  

Microsoft Academic Search

This paper presents a method based on genetic algorithms and neural networks suitable for finding the five parameters of the Jiles-Atherton (JA) model for generalization to dynamic hysteresis loops. The aim is to obtain an equivalent static model for dynamic loops by updating its parameters varying the frequency of the imposed magnetic field H(t). Validations of the present approach compared

Alessandro Salvini; Francesco Riganti Fulginei

2002-01-01

60

Element-specific hysteresis loop measurements on Individual 35 nm islands with scanning transmission X-ray microscopy.  

PubMed

Using scanning transmission X-ray microscopy combined with X-ray magnetic circular dichroism, element-specific hysteresis loops with a 25 nm X-ray probe are obtained on 35 nm Fe/Gd multilayer nanoislands fabricated by extreme ultra-violet interference lithography. Local hysteresis loops measured for the individual islands and the antidot film between the islands display similar behavior resulting from the lateral confinement. Line scan measurements confirm ferrimagnetic coupling between Fe and Gd in the patterned region. The ability to measure magnetization reversal with X-rays at high spatial resolution will provide an important tool for future characterization of sub-50 nm nanostructures. PMID:22755078

Luo, Feng; Eimüller, Thomas; Amaladass, Edward; Lee, Ming Sang; Heyderman, Laura J; Solak, Harun H; Tyliszczak, Tolek

2012-03-01

61

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

62

Numerical characterization of the density of metastable states within the hysteresis loop in disordered systems  

NASA Astrophysics Data System (ADS)

An improved approach is proposed to analyze the density of metastable states within any hysteresis loop, such as those observed in magnetic materials or for adsorption in porous materials. Except for a few analytically tractable models, most calculations have to be performed numerically on finite systems. The main points to be addressed thus concern the average over various material samples (the so-called realizations of the disorder), and the finite size analysis to estimate the thermodynamic limit. As an improvement of previously existing methods, it is proposed to introduce the Fourier transform of the density of metastable states (characteristic function). Its logarithm is shown to be additive and can straightforwardly be averaged over disorder. This procedure leads to a new definition of the complexity in finite size, giving the usual quenched complexity in the thermodynamic limit, while being better suited to performing finite size analysis. The calculations are illustrated on a molecular simulation based model for a simple fluid adsorbed in heterogeneous siliceous tubular pores mimicking mesoporous materials like MCM-41 or porous silicon. This approach is expected to be of general interest for hysteresis phenomena, including magnetic materials.

Puibasset, Joël

2011-01-01

63

Self-magnetic compensation and shifted hysteresis loops in ferromagnetic samarium systems  

NASA Astrophysics Data System (ADS)

For Sm3+ ions in a vast majority of metallic systems, the following interesting scenario has been conjured up for long, namely, a magnetic lattice of tiny self- (spin-orbital) compensated 4f -moments exchange coupled (and phase reversed) to the polarization in the conduction band. We report here the identification of a self-compensation behavior in a variety of ferromagnetic Sm intermetallics via the fingerprint of a shift in the magnetic hysteresis (M-H) loop from the origin. Such an attribute, designated as exchange bias in the context of ferromagnetic/antiferromagnetic multilayers, accords these compounds a potential for niche applications in spintronics. We also present results on magnetic compensation behavior on small Gd doping (2.5at.%) in one of the Sm ferromagnets (viz., SmCu4Pd ). The doped system responds like a pseudoferrimagnet and it displays a characteristic left-shifted linear M-H plot for an antiferromagnet.

Kulkarni, P. D.; Dhar, S. K.; Provino, A.; Manfrinetti, P.; Grover, A. K.

2010-10-01

64

Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities  

DOEpatents

A marker for an electronic article surveillance system is disclosed comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that, upon exposure of the marker to an external magnetic field whose field strength in the direction opposing the instantaneous magnetic polarization of the marker exceeds a predetermined threshold value, there results a regenerative reversal of the magnetic polarization of the marker. An electronic article surveillance system and a method utilizing the marker are also disclosed. Exciting the marker with a low frequency and low field strength, so long as the field strength exceeds the low threshold level for the marker, causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.

Humphrey, Floyd B. (Bradfordwoods, PA) [Bradfordwoods, PA

1987-01-01

65

Magnetic Barkhausen Noise and hysteresis loop in commercial carbon steel: influence of applied tensile stress and grain size  

Microsoft Academic Search

The influence of applied tensile stress and grain size on Magnetic Barkhausen Noise and hysteresis loops in 1005 commercial steel is studied in this work. The peak amplitude of the Barkhausen voltage increases with the applied stress, reaching a maximum value and then beginning to decrease at higher tensile stress. This behavior is explained regarding the domain wall dynamics by

J. Anglada-Rivera; L. R Padovese; J. Capo-Sanchez

2001-01-01

66

Introduction of thermal activation in forward modeling of hysteresis loops for single-domain magnetic particles and implications for the interpretation of the Day diagram  

Microsoft Academic Search

Synthetic hysteresis loops were generated by numerically solving the classical Stoner-Wohlfarth model and a thermally activated Stoner-Wohlfarth model for a set of randomly oriented magnetic grains. Although computationally intensive this method allows forward modeling of hysteresis loops of single-domain (SD) and viscous grains. In the classic Stoner-Wohlfarth model the shape of the modeled loops can be modified by changing the

Luca Lanci; Dennis V. Kent

2003-01-01

67

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

68

Domains and Hysteresis Loops in Ferroelectric Thin Films with Metallic and Semiconductor Electrodes  

NASA Astrophysics Data System (ADS)

Detailed thermodynamic description of the ferroelectric (FE) thin films with metallic and semiconductor electrodes is presented. We show that imperfect screening by the electrodes results in uncompensated depolarizing field and leads to a tilt of the hysteresis loops, as observed experimentally. We solve for the domain instability analytically and find a simple criterion for stability of homogeneously polarized state in thin films with realistic metallic electrodes. In most cases the film breaks into domains, and they can exist in near cubic (perovskite) ferroelectrics down to ``atomic'' thicknesses (one unit cell thick). Domain structures under bias voltage are investigated. In the case of semiconductor electrodes the screening is poor at small values of polarization P and highly nonlinear at larger P close to a spontaneous polarization in the bulk. This formally allows for the ``Batra-like'' jumpwise transition at lowering temperature, which is not observed since it is preempted by domain instability. Additional boundary conditions [1] modify the above behavior, but mainly for a homogeneous state. The unusual phase behavior in cases of symmetric and asymmetric boundary conditions is discussed together with available experimental data.[1] A. M. Bratkovsky and A. P. Levanyuk, Phys. Rev. Lett. 94, 107601 (2005) and to be published.

Bratkovsky, A. M.; Levanyuk, A. P.

2006-03-01

69

Phase transition and hysteresis loop in structured games with global updating.  

PubMed

We present a global payoff-based strategy updating model for studying cooperative behavior of a networked population. We adopt the Prisoner's Dilemma game and the snowdrift game as paradigms for characterizing the interactions among individuals. We investigate the model on regular, small-world, and scale-free networks, and find multistable cooperation states depending on the initial cooperator density. In particular for the snowdrift game on small-world and scale-free networks, there exist a discontinuous phase transition and hysteresis loops of cooperator density. We explain the observed properties by theoretical predictions and simulation results of the average number of neighbors of cooperators and defectors, respectively. Our work indicates that individuals with more neighbors have a trend to preserve their initial strategies, which has strong impacts on the strategy updating of individuals with fewer neighbors; while the fact that individuals with few neighbors have to become cooperators to avoid gaining the lowest payoff plays significant roles in maintaining and spreading of cooperation strategy. PMID:18517692

Wang, Wen-Xu; Lü, Jinhu; Chen, Guanrong; Hui, P M

2008-04-01

70

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope.  

PubMed

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

71

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope  

PubMed Central

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

72

Physical motivations of the constitutive relations for ferroelectric ceramics and the existence of butterfly and hysteresis loops  

SciTech Connect

The responses of ferroelectric ceramics can be quite complex depending on the physical processes to which they are subjected. Their mechanical, electromechanical and dielectric properties depend on domain switching, dipole dynamics and phase transformation which can be caused by external stimuli such as mechanical and electrical loadings, and temperature variations. A theory, taking into account the effects of domain switching and dipole dynamics, has been formulated, and in its present stage of development is sufficient to characterize various observable resonses. Specifically, a special case of the theory predicts the nature of the butterfly and hysteresis loops. The butterfly and hysteresis loops are manifestations of the mechanical, electro-mechanical and dielectric responses due to domain switching produced by cyclic electric fields. Comparisons of the predictions of the theory with experimental results are made in a pseudo one dimensional context.

Chen, P.J.

1982-01-01

73

The cyclic stress-strain properties, hysteresis loop shape, and kinematic hardening of two high-strength bearing steels  

Microsoft Academic Search

Measurements of the shapes of the cyclic, stress-strain hysteresis loops obtained from AISI 1070 (HRC 60) and AISI 52100 (HRC\\u000a 62) steels subjected to constant stress and constant plastic strain amplitude cycles in torsion are presented. The study examines\\u000a plastic strain amplitudes in the range of 0.0002 ? ??p\\/2? 0.0015, which are similar to the strain amplitudes produced by rolling

G. T. Hahn; V. Bhargava; Q. Chen

1990-01-01

74

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

Microsoft Academic Search

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

75

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

76

Hysteresis loop with controllable shape and direction in an optical ring cavity  

SciTech Connect

We have experimentally observed a 'backward' (clockwise rotating) hysteresis cycle in the system of an optical ring cavity containing three-level ({lambda}-type configuration) rubidium atoms. The shape and direction of the observed hysteresis cycles can be easily controlled with experimental parameters. Such an interesting phenomenon is caused by the greatly modified absorption, dispersion, and nonlinear optical properties of the three-level atomic medium, due to the induced atomic coherence.

Joshi, Amitabh; Yang Wenge; Xiao Min [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2004-10-01

77

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

78

Room temperature study of the optical switching of a spin crossover compound inside its thermal hysteresis loop  

NASA Astrophysics Data System (ADS)

We have studied the low-spin to high spin state phase transition induced by a single or a sequence of nanosecond laser pulses within the thermal hysteresis loop of the [Fe(NH2-trz)3](NO3)2-H2O spin crossover compound. We demonstrate that the final state that is photoinduced can be finely controlled by changing the central wavelength and the energy of the laser pulses. A simple model accounts for the observed phenomena and paves the way for the practical applications to optical data storage at room temperature of spin state transition compounds.

Gallé, G.; Deldicque, D.; Degert, J.; Forestier, Th.; Létard, J.-F.; Freysz, E.

2010-01-01

79

Supercooling of the disordered vortex phase via minor hysteresis loops in 2H-NbSe2  

NASA Astrophysics Data System (ADS)

We report on the observation of novel features in the minor hysteresis loops in a clean crystal of 2H-NbSe2, which displays a peak effect. The observed behavior can be explained in terms of a supercooling of the disordered vortex phase while cooling the superconductor in a field. Also, the extent of spatial order in a flux-line lattice formed in ascending fields is different from (and larger than) that in the descending fields below the peak position of the peak effect; this is attributed to a different degree of reorganization of the vortex state induced by changes in the field in the two cases.

Ravikumar, G.; Mishra, P. K.; Sahni, V. C.; Banerjee, S. S.; Grover, A. K.; Ramakrishnan, S.; Gammel, P. L.; Bishop, D. J.; Bucher, E.; Higgins, M. J.; Bhattacharya, S.

2000-05-01

80

Dipole spring ferroelectrics in superlattice SrTiO3/BaTiO3 thin films exhibiting constricted hysteresis loops  

SciTech Connect

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

81

Physical interpretation of hysteresis loops: Micromagnetic modeling of fine particle magnetite  

Microsoft Academic Search

Hysteresis measurements have become an important part of characterizing magnetic behavior of rocks in paleomagnetic studies. Theoretical interpretation is often difficult owing to the complexity of mineral magnetism and published data sets demonstrate remanence and coercivity behavior that is currently unexplained. In the last decade, numerical micromagnetic modeling has been used to simulate magnetic particles. Such simulations reveal the existence

Lisa Tauxe; H. Neal Bertram; Christian Seberino

2002-01-01

82

3D and 1D calculation of hysteresis loops and energy products for anisotropic nanocomposite films with perpendicular anisotropy  

NASA Astrophysics Data System (ADS)

In this paper, the magnetic reversal process, hysteresis loops and energy products for exchange-coupled Nd2Fe14B/?-Fe bilayers are studied systematically by a three-dimensional (3D) model. The 3D calculations are numerically solved using the finite difference method, where the results are carefully compared with those calculated by one-dimensional (1D) model. It is found that the calculated hysteresis loops and energy products based on the two methods are consistent with each other. Both nucleation fields and coercivities decrease monotonically as the soft layer thickness Ls increases. In addition, the calculated spatial distributions of magnetization orientations in the thickness direction at various applied fields based on both methods signify a three-step magnetic reversal process, which are nucleation, growth and displacement of the domain wall. The calculated magnetic orientations within the film plane, however, are totally different according to the two methods. The 3D calculation exhibits a process of vortex formation and annihilation. On the other hand, the 1D calculation gives a quasi-coherent one, where magnetization orientation is coherent in the film plane and varies in the thickness direction. This new reversal mechanism displayed in the film plane has a systematic influence on the nucleation fields, coercivity and energy products.

Yuan, X. H.; Zhao, G. P.; Yue, Ming; Ye, L. N.; Xia, J.; Zhang, X. C.; Chang, J.

2013-10-01

83

One-dimensional quasistatic nonisothermal evolution of shape-memory material inside the hysteresis loop  

Microsoft Academic Search

We study in this paper the quasistatic nonisothermal processes of a onedimensional bar consisting of a two-phase shape-memory material. The system of p.d.e.'s governing the evolution of the bar is obtained by means of a temperature-dependent hysteretic stress-strain law that we formulate as a “plasticity” criterion and a hysteresis operator. The constitutive theory is developed here on the basis of

B. Fedelich; G. Zanzotto

1991-01-01

84

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

Microsoft Academic Search

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

85

The origin of the double-triangle hysteresis loops in ErFeO3 near the low temperature erbium ordering transition  

NASA Astrophysics Data System (ADS)

Magnetic properties of an orthoferrite ErFeO3 are determined by the iron and the rare-earth magnetic ions. Interactions between magnetic sub-systems of ErFeO3 lead to a sequence of orientation phase transitions observed in this material. In this work hysteresis loops in single crystal ErFeO3 samples were studied below the spin-rotation transition region, T < 80 K. Above and around the compensation point Tcomp= 46 K the hysteresis loops are rectangular, with the coercive force diverging at Tcomp. As the temperature is lowered towards the erbium ordering transition TN2= 4.1 K, the shape of the loops experiences a dramatic change. At 20 K the loops develop triangular ``tails.'' At 10 K the triangles become prominent while the central rectangular part near H = 0 collapses. A double-loop hysteresis pattern with two triangular loops emerges. We explain this behavior by a domain wall motion reversal mechanism with negligible pinning of the walls in the sample. The transition from the rectangular to the double-triangle loops is due to the competition between the energy barrier of wall nucleation and the demagnetization energy gain achieved by placing the wall inside the sample. Our model explains well the correlation of the loop's shapes and sizes with the total magnetization of ErFeO3.

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

2009-03-01

86

Generalization of the Classical Method for Calculating Dynamic Hysteresis Loops in Grain-Oriented Electrical Steels  

Microsoft Academic Search

We have studied the ability of two one-dimensional (1-D) time-stepping models, both based on the concept of magnetic viscosity, to reproduce dynamic loops and losses in grain-oriented (GO) electrical steels under arbitrary magnetization regimes. We found that GO steels (0.3 mm thick) can be modeled quite accurately at magnetizing frequencies up to 200 Hz by a thin sheet representation, which

Sergey E. Zirka; Yuri I. Moroz; Philip Marketos; Anthony J. Moses; David C. Jiles; T. Matsuo

2008-01-01

87

Dipole spring ferroelectrics in superlattice SrTiO3/BaTiO3 thin films exhibiting constricted hysteresis loops  

SciTech Connect

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 multilayers stack behave as dipole spring ferroelectric, named in analogy to exchange spring magnets in magnetic multilayers that show similar loops.

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

2012-03-01

88

Disorder-driven hysteresis-loop criticality in Co/CoO-films.  

SciTech Connect

The effect of magnetic disorder on the magnetization reversal process in thin Co/CoO-films has been investigated. The antiferromagnetic CoO layer allows a reversible tuning of the magnetic disorder by simple temperature variation. For temperatures above a critical temperature T{sub c}, we observe a discontinuous magnetization reversal, whereas smooth magnetization loops occur for T < T{sub c}. Our measurements establish the existence of a disorder-driven critical point in the non-equilibrium phase diagram. In addition, we observe scaling behavior in the vicinity of the critical point and determine the critical exponents to {beta} = 0.022 {+-} 0.006 and {beta}{delta} = 0.30 {+-} 0.03.

Berger, A.; Inomata, A.; Jiang, J. S.; Pearson, J. E.; Bader, S. D.

2000-11-01

89

Disorder-driven hysteresis loop criticality in Co/CoO-films  

NASA Astrophysics Data System (ADS)

We have studied the effect of magnetic disorder on the magnetization reversal process in thin Co/CoO-bilayer films. This particular material system, in which a ferromagnetic Co film is in contact with an antiferromagnetic (AFM) CoO overlayer, was chosen for two reasons. First, the thin film geometry with in-plane orientation of the magnetization suppresses the influence of dipolar effects. This is important, because true criticality should only be observable in the limit of vanishing demagnetizing effects . Secondly, the exchange coupled AFM CoO-layer in combination with the Co/CoO-interface roughness allows the reversible tuning of the effective magnetic disorder by varying the temperature in the vicinity of the CoO Neel temperature. For temperatures above a critical temperature Tc, we observe a discontinuous magnetization reversal, whereas smooth magnetization loops occur for T < Tc. Our measurements firmly establish the existence of a disorder-driven critical point in the non-equilibrium phase diagram as predicted by theoretical investigations based on the random-field Ising model [1]. In addition, we observe scaling behavior in the vicinity of the critical point and determine the critical exponents b = 0.022 ± 0.006 and bd = 0.30 ± 0.03 for this two-dimensional non-equilibrium system [2]. [1] Olga Perkovic et al., Phys. Rev. Lett. 75, 4528 (1995); [2] A. Berger et al., Phys. Rev. Lett. 85, 4176 (2000)

Berger, A.; Inomata, A.; Jiang, J. S.; Pearson, J. E.; Bader, S. D.

2001-03-01

90

Magnetic and eddy current effects in an open-loop pulsed hysteresis graph system for magnetization of rare-earth magnets  

Microsoft Academic Search

Describes an open-loop pulsed hysteresis graph system that is capable of magnetizing ceramic and rare-earth permanent magnets such as neodymium, samarium cobalt, and Alnico in cylindrical and rectangular shapes. The prototype system relies on an air-core excitation coil with an inner diameter of 3 cm and a length of 10 cm. A pulsed power supply provides a transient current pulse

R. Ludwig; P. Bretchko; S. Makarov

2002-01-01

91

Lags and Hysteresis Loops of Cosmic Ray Intensity Versus Sunspot Numbers: Quantitative Estimates for Cycles 19 - 23 and a Preliminary Indication for Cycle 24  

NASA Astrophysics Data System (ADS)

Hysteresis plots between cosmic-ray (CR) intensity (recorded at the Climax station) and sunspot relative number R Z show broad loops in odd cycles (19, 21, and 23) and narrow loops in even cycles (20 and 22). However, in the even cycles, the loops are not narrow throughout the whole cycle; around the sunspot-maximum period, a broad loop is seen. Only in the rising and declining phases, the loops are narrow in even cycles. The CR modulation is known to have a delay with respect to R Z, and the delay was believed to be longer in odd cycles (19, 21, and 23; about 10 months) than the delay in even cycles (20 and 22; about 3 - 5 months). When this was reexamined, it was found that the delays are different during the sunspot-minimum periods (2, 6, and 14 months for odd cycles and 7 and 9 months for even cycles) and sunspot-maximum periods (0, 4, and 7 months for odd cycles and 5 and 8 months for even cycles). Thus, the differences between odd and even cycles are not significant throughout the whole cycle. In the recent even cycle 24, hysteresis plots show a preliminary broadening near the sunspot maximum, which occurred recently (February 2012). The CR level (recorded at Newark station) is still high in 2013, indicating a long lag (exceeding 10 months) with respect to the sunspot maximum.

Kane, R. P.

2014-07-01

92

Dynamic hysteresis modelling  

Microsoft Academic Search

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

93

PSPICE computer modeling of hysteresis effects  

Microsoft Academic Search

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

94

Mechanism of the hysteretic behavior of the magnetoresistance of granular HTSCs: The universal nature of the width of the magnetoresistance hysteresis loop  

SciTech Connect

The hysteretic behavior of the magnetoresistance R(H) of granular high-temperature superconductors (HTSCs) of the Y-Ba-Cu-O, Bi-Ca-Sr-Cu-O, and La-Sr-Cu-O classical systems is investigated for transport current densities lower and higher than the critical density (at H = 0). All systems exhibit universal behavior of the width of the magnetoresistance hysteresis loop: independence of transport current under identical external conditions. This means that flux trapping in HTSC grains is the main mechanism controlling the hysteretic behavior of the magnetoresistance of granular HTSCs, while pinning of Josephson vortices in the intragranular medium makes no appreciable contribution to the formation of magnetoresistance hysteresis (when transport current flows through the sample). Experimental data on relaxation of residual resistance after the action of a magnetic field also confirm this conclusion.

Balaev, D. A., E-mail: smp@iph.krasn.ru; Dubrovskii, A. A.; Shaikhutdinov, K. A.; Popkov, S. I.; Gokhfeld, D. M.; Gokhfeld, Yu. S.; Petrov, M. I. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Branch (Russian Federation)

2009-02-15

95

Charge transfer phase transition with reversed thermal hysteresis loop in the mixed-valence Fe9[W(CN)8]6·xMeOH cluster.  

PubMed

A bimetallic pentadecanuclear cyanido-bridged {Fe9[W(CN)8]6 (MeOH)24}·xMeOH cluster of an Fe(II/III)-W(IV/V) mixed valence nature, reveals a reversible single-crystal-to-single-crystal transformation, concomitant with metal-to-metal charge transfer between Fe and W ions. The dominance of (HS)Fe(II)-NC-W(V) units at a high temperature, and (HS)Fe(III)-NC-W(IV) units at a low temperature, leads to an unprecedented reversed thermal hysteresis loop in magnetic measurements. PMID:24555182

Chorazy, Szymon; Podgajny, Robert; Noga?, Wojciech; Nitek, Wojciech; Kozie?, Marcin; Rams, Micha?; Juszy?ska-Ga??zka, Ewa; ?ukrowski, Jan; Kapusta, Czes?aw; Nakabayashi, Koji; Fujimoto, Takashi; Ohkoshi, Shin-ichi; Sieklucka, Barbara

2014-04-01

96

Velocity of the high-spin low-spin interface inside the thermal hysteresis loop of a spin-crossover crystal, via photothermal control of the interface motion.  

PubMed

We investigated by optical microscopy the thermal transition of the spin-crossover dinuclear iron(II) compound [(Fe(NCSe)(py)(2))(2)(m-bpypz)]. In a high-quality crystal the high-spin (HS) low-spin (LS) thermal transition took place with a sizable hysteresis, at ~108 K and ~116 K on cooling and heating, respectively, through the growth of a single macroscopic domain with a straight LS and HS interface. The interface orientation was almost constant and its propagation velocity was close to ~6 and 26 ? m s(-1) for the on-cooling and on-heating processes, respectively. We found that the motion of the interface was sensitive to the intensity of the irradiation beam of the microscope, through a photothermal effect. By fine-tuning the intensity we could stop and even reverse the interface motion. This way we stabilized a biphasic state of the crystal, and we followed the spontaneous motion of the interface at different temperatures inside the thermal hysteresis loop. This experiment gives access for the first time to an accurate determination of the equilibrium temperature in the case of thermal hysteresis--which was not accessible by the usual quasistatic investigations. The temperature dependence of the propagation velocity inside the hysteretic interval was revealed to be highly nonlinear, and it was quantitatively reproduced by a dynamical mean-field theory, which made possible an estimate of the macroscopic energy barrier. PMID:23473199

Slimani, Ahmed; Varret, François; Boukheddaden, Kamel; Garrot, Damien; Oubouchou, Hassane; Kaizaki, Sumio

2013-02-22

97

Analysis of Hysteresis Measurements in Epitaxial SRO\\/PZT\\/Pt Capacitor Structures  

Microsoft Academic Search

P-E hysteresis loops were measured in SrRuO3\\/Pb(Zr0.52Ti0.48)O3\\/Pt capacitor structures grown on (100) SrTiO3 single-crystal substrates using high-oxygen pressure on axis dc-sputtering technique. PZT films were grown by rf magnetron sputtering in a pure oxygen atmosphere. Capacitor structures with electrode areas of 5.0 × 10 and 6.5 × 10cm revealed clear hysteretic behavior. These hysteresis loops displayed asymmetric behavior due to

J. Realpe; A. Cortes; E. Delgado; W. Lopera; P. Prieto

2006-01-01

98

Real space mapping of polarization dynamics and hysteresis loop formation in relaxor-ferroelectric PbMg1/3Nb2/3O3 PbTiO3 solid solutions  

SciTech Connect

Polarization switching in ergodic relaxor and ferroelectric phases in the PbMg1/3Nb2/3O3 PbTiO3 (PMN-PT) system is studied using piezoresponse force microscopy, single point electromechanical relaxation measurements, and voltage spectroscopy mapping. The dependence of relaxation behavior on voltage pulse amplitude and time is found to follow a universal logarithmic behavior with a nearly constant slope. This behavior is indicative of the progressive population of slow relaxation states, as opposed to a linear relaxation in the presence of a broad relaxation time distribution. The role of relaxation behavior, ferroelectric nonlinearity, and the spatial inhomogeneity of the tip field on hysteresis loop behavior is analyzed in detail. The hysteresis loops for ergodic PMN-10%PT are shown to be kinetically limited, while in PMN with larger PT content, true ferroelectric hysteresis loops with low nucleation biases are observed.

Rodriguez, Brian [University College, Dublin; Jesse, Stephen [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Svechnikov, S. V. [National Academy of Science of Ukraine, Kiev, Ukraine; Kiselev, Dmitri [University of Aveiro, Portugal

2010-01-01

99

Butterfly Hysteresis Loop and Dissipative Spin Reversal in the S = 1\\/2, V15 Molecular Complex  

Microsoft Academic Search

Time resolved magnetization measurements have been performed on a spin 1\\/2 molecular complex, so-called V15. Despite the absence of a barrier, magnetic hysteresis is observed over a time scale of several seconds. A detailed analysis in terms of a dissipative two-level model is given, in which fluctuations and splittings are of the same energy. Spin-phonon coupling leads to long relaxation

I. Chiorescu; W. Wernsdorfer; A. Müller; H. Bögge; B. Barbara

2000-01-01

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

High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys  

NASA Technical Reports Server (NTRS)

Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

1990-01-01

102

High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys  

NASA Technical Reports Server (NTRS)

Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

1990-01-01

103

High Frequency, High Temperature Specific Core Loss and Dynamic BH Hysteresis Loop Characteristics of Soft Magnetic Alloys  

Microsoft Academic Search

Limited experimental data exists for the specific core loss and dynamic B-H loops for s oft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 C under

W. R. Wieserman; G. E. Schwarze; J. M. Niedra

1990-01-01

104

Preisach modeling of piezoceramic and shape memory alloy hysteresis  

Microsoft Academic Search

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

105

Preisach modeling of piezoceramic and shape memory alloy hysteresis  

Microsoft Academic Search

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

106

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

107

Thermo-magnetic history effects in the giant magnetostriction across the first-order transition and minor hysteresis loops modeling in Fe0.955Ni0.045Rh alloy  

NASA Astrophysics Data System (ADS)

Results of temperature- and magnetic field-dependent strain measurements across the first-order antiferromagnetic to ferromagnetic phase transition in Fe0.955Ni0.045Rh are presented. Distinct thermal and magnetic field hystereses are observed in the measured strain across the phase transition. The minor hysteresis loops inside the hysteretic regime across the temperature-driven transition are modeled using the Preisach model of hysteresis. The applicability of the Preisach model to explain the general features of minor hysteresis loops is discussed for a disorder influenced first-order transition. The minor hysteresis loops show the property of retaining the memory of the starting or end point of the temperature cycle followed within the hysteretic region. A larger temperature excursion within the hysteretic region wipes out the memory of a smaller temperature cycle which contains one of the extrema of the larger cycle. The end-point memory and the wiping-out property of the minor hysteresis loops can be described quite well within the Preisach model, irrespective of the temperature history followed to reach a particular starting point. Thermo-magnetic history effects across the magnetic field-induced transition are explained, which will enable the choice of the starting point of an experimental cycle in the field-temperature phase space so as to achieve the desired functionality. Our results highlight the necessity to understand the influence of disorder on a first-order phase transition so as to achieve a repeatable performance of materials whose functionalities are based on such a transition.

Manekar, Meghmalhar; Sharma, V. K.; Roy, S. B.

2012-05-01

108

Phonon bottleneck effect leads to observation of quantum tunneling of the magnetization and butterfly hysteresis loops in ( Et4 N)3 Fe2 F9  

NASA Astrophysics Data System (ADS)

A detailed investigation of the unusual dynamics of the magnetization of (Et4N)3Fe2F9 (Fe2) , containing isolated [Fe2F9]3- dimers, is presented and discussed. Fe2 possesses an S=5 ground state with an energy barrier of 2.40K due to an axial anisotropy. Poor thermal contact between sample and bath leads to a phonon bottleneck situation, giving rise to butterfly-shaped hysteresis loops below 5K concomitant with slow decay of the magnetization for magnetic fields Hz applied along the Fe?Fe axis. The butterfly curves are reproduced using a microscopic model based on the interaction of the spins with resonant phonons. The phonon bottleneck allows for the observation of resonant quantum tunneling of the magnetization at 1.8K , far above the blocking temperature for spin-phonon relaxation. The latter relaxation is probed by ac magnetic susceptibility experiments at various temperatures and bias fields HDC . At HDC=0 , no out-of-phase signal is detected, indicating that at T?1.8K Fe2 does not behave as a single-molecule magnet. At HDC=1kG , relaxation is observed, occurring over the barrier of the thermally accessible S=4 first excited state that forms a combined system with the S=5 state.

Schenker, Ralph; Leuenberger, Michael N.; Chaboussant, Grégory; Loss, Daniel; Güdel, Hans U.

2005-11-01

109

High coercive FePt and FePt-SiNx(001) films with small grain size and narrow opening-up of in-plane hysteresis loop by TiN intermediate layer  

NASA Astrophysics Data System (ADS)

The effects of a TiN intermediate layer on the epitaxial growth and magnetic properties of FePt films were investigated. It was found that 5 nm TiN can effectively block the diffusion of a CrRu underlayer into a FePt magnetic layer and the magnetic dead layer on the TiN layer was negligible. Compared with an FePt film grown on a MgO intermediate layer, FePt film grown on a TiN interlayer exhibited very high out-of-plane coercivity and very narrow opening-up of in-plane hysteresis loop. With doping 40 vol. % SiNx in FePt film the grain size was reduced to 5.5 nm and the magnetic properties, such as high out-of-plane coercivity and line-like in-plane hysteresis loop, were retained.

Li, H. H.; Dong, K. F.; Peng, Y. G.; Ju, G.; Chow, G. M.; Chen, J. S.

2011-08-01

110

Modeling of Hysteresis Losses Applied to Slotless Permanent Magnet Motors  

Microsoft Academic Search

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

111

Analysis of Hysteresis Losses in Synchronous Permanent Magnet Motors  

Microsoft Academic Search

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

112

Ferroelectric BaTiO3/BaZrO3 superlattices: X-ray diffraction, Raman spectroscopy, and polarization hysteresis loops  

NASA Astrophysics Data System (ADS)

Artificial superlattices (SLs) consisting of ferroelectric BaTiO3 (BT) and paraelectric BaZrO3 (BZ) have been growth by a pulsed laser deposition technique. The epitaxial BT and BZ layers with a periodicity from 16 A? to 1056 A? were sequentially deposited on (001) MgO substrate buffered with an oxide conducting layer of La1/2Sr1/2CoO3. The out-of-plane lattice parameters of the SLs constituents were determined by modeling of the x-ray diffractograms. The results indicate that the polar c-axis of the BT layers lies in the plane of the substrate and BZ layers exhibit enhanced tetragonal distortion which is induced by the mismatch between the alternating BZ and BT layers. The Raman data reinforces this interpretation and suggest a monoclinic phase in BT layers and polar phase in BZ layers. The Raman spectra give evidence of coupling between the constituent layers and a narrowing of the Raman peaks is attributed to a reduction in the disorder of the Ti4+ ions due to the epitaxial strain. This strain is responsible for the upward frequency shift in the soft modes, especially, the E(1TO) mode, which is markedly altered with respect to its analogs in BT-bulk crystal and BT thin film. Ferroelectric hysteresis loops measurements, confirmed the x-ray diffraction and Raman results, and revealed a clear ferroelectric behavior for the constrained SLs (32 A?<=?<=256 A?) while a weak ferroelectricity is observed for the large periods (?=500 A? and 1056 A?). This is attributed to the strain-induced ferroelectricity in BZ layers for the constrained SLs.

El Marssi, M.; Gagou, Y.; Belhadi, J.; de Guerville, F.; Yuzyuk, Yu. I.; Raevski, I. P.

2010-10-01

113

Hysteresis Simulation  

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

114

Preisach modeling of piezoceramic and shape memory alloy hysteresis  

Microsoft Academic Search

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

115

Hysteresis loops of polarization and magnetization in (BiNd 0.05)(Fe 0.97Mn 0.03)O 3\\/Pt\\/CoFe 2O 4 layered epitaxial thin film grown by pulsed laser deposition  

Microsoft Academic Search

(BiNd0.05)(Fe0.97Mn0.03)O3 (BNFM)\\/Pt\\/CoFe2O4 (CFO) layered thin film was fabricated on (100) SrTiO3 substrate by pulsed laser deposition. BNFM, Pt, and CFO layers were epitaxially grown on the substrate. Almost no increase of leakage current due to the formation of heteroepitaxial structure was found, and well-saturated hysteresis loops in the polarization vs electric field and magnetization vs magnetic field curves coexist at

Takeshi Kawae; Jie Hu; Hiroshi Naganuma; Takeshi Nakajima; Yuki Terauchi; Soichiro Okamura; Akiharu Morimoto

2011-01-01

116

Hysteresis phenomena of the intelligent driver model for traffic flow.  

PubMed

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

117

A magnetic hysteresis model  

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

118

Potbellies, wasp-waists, and superparamagnetism in magnetic hysteresis  

Microsoft Academic Search

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

119

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

120

Mechanical hysteresis due to microplasticity in alumina with microcracks  

Microsoft Academic Search

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

121

Anomalous position of the maximum in magnetic hysteresis loops measured on (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}/Ag tapes  

SciTech Connect

An anomalous position of the central peak of magnetic hysteresis loops is observed in (Bi,Pb)-2223/Ag tapes at positive external fields B{sub ext} for dB{sub ext}/dt{lt}0. We model the grain structure by a system of superconducting disk-shaped grains touching each other in small, but highly conducting contacts at the disk circumferences. The sign of the internal field B{sub i} at the circumference of large, thin well oriented grains in the tape plays an important role. While in great majority of the sample volume B{sub i} is delayed behind B{sub ext}, just at the grain circumferences B{sub i} might be considerably ahead of B{sub ext}. Based on these considerations, a model sample which should exhibit similar features of the central peak is proposed. {copyright} {ital 1997} {ital American Institute of Physics}

Koblischka, M.R.; Galkin, L.P.; Nalevka, P. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18040 Praha 8, (Czech Republic).] [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18040 Praha 8, (Czech Republic).

1997-01-01

122

A Trinuclear Defect-Grid Iron(II) Spin Crossover Complex with a Large Hysteresis Loop that is Readily Silenced by Solvent Vapor.  

PubMed

A new type of [2×2] matrix-like complexes with one vertex devoid of a metal ion has been selectively synthesized. The defect-grid triiron(II) complex exhibits a sharp and complete spin-crossover (SCO) from the 1HS-2LS to the 2HS-1LS state (HS: high spin; LS: low spin) with wide hysteresis near room temperature. Although the "structurally soft" H-bonded vertex, elastically coupled to the metal ions, accounts for the stabilization of spin states, it also mediates a dramatic, yet reversible, response to the uptake of exogenous solvent molecules leading to silencing of the SCO. The high sensitivity towards those guest molecules, the short response time upon exposure, and the smooth reversibility of guest binding are favorable characteristics for future sensing applications of such defect grids. PMID:24854423

Steinert, Markus; Schneider, Benjamin; Dechert, Sebastian; Demeshko, Serhiy; Meyer, Franc

2014-06-10

123

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

124

Large capacitance-voltage hysteresis loops in SiO{sub 2} films containing Ge nanocrystals produced by ion implantation and annealing  

SciTech Connect

Metal-oxide-semiconductor structures containing Ge nanocrystals (NCs) of 3-4 nm diameter and 2x10{sup 12} cm{sup -2} density are shown to exhibit capacitance-voltage hysteresis of 20.9 V, one of the largest observed in Ge-NC based nonvolatile memories. The Ge NCs were fabricated in an oxide of 30 nm thickness by ion implantation with 30 keV Ge{sub 2}{sup -} ions to an equivalent fluence of 1x10{sup 16} Ge cm{sup -2} followed by annealing at 950 deg. C for 10 min. Secondary ion mass spectroscopy and transmission electron microscopy demonstrate the existence of Ge NCs whose average distance from the SiO{sub 2}/Si interface is about 6.7 nm. It is shown that the memory effect is a likely consequence of charge trapping at Ge NCs and that it is enhanced by accurately controlling the distribution of Ge NCs with respect to the Si/SiO{sub 2} interface.

Park, C.J.; Cho, K.H.; Yang, W.-C.; Cho, H.Y.; Choi, Suk-Ho; Elliman, R.G.; Han, J.H.; Kim, Chungwoo [Department of Physics and Quantum-Functional Semiconductor Research Center, Dongguk University, Seoul 100-715 (Korea, Republic of); Department of Physics and Applied Physics, College of Electronics and Informations, Kyung Hee University, Suwon 449-701 (Korea, Republic of); Electronic Materials Engineering Department, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT0200 (Australia); Semiconductor R and D Center Memory Division, Samsung Electronics Co. LTD., Kyunggi-do, 449-711 (Korea, Republic of)

2006-02-13

125

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

126

A phenomenological mathematical model of hysteresis  

Microsoft Academic Search

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

127

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

128

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

Microsoft Academic Search

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

129

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

130

Mathematical models of hysteresis  

Microsoft Academic Search

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

131

Hysteresis in Metal Hydrides.  

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

132

A neuro-genetic and time-frequency approach to macromodeling dynamic hysteresis in the harmonic regime  

Microsoft Academic Search

A numerical approach for the evaluation of hysteresis loops in the harmonic regime is presented. Genetic algorithms (GAs) are used to train neural networks (NNs) with the aim of generalizing the Jiles-Atherton (JA) static hysteresis model for dynamic loops. The NN training is based on symmetrical and asymmetrical, major and minor loops under sinusoidal excitation with or without offset. Subsequently,

Alessandro Salvini; Francesco Riganti Fulginei; Christian Coltelli

2003-01-01

133

Fourier analysis of digital hysteresis data: rock magnetic applications  

Microsoft Academic Search

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

134

Tracking Control of Piezoelectric Actuators by Feedforward Hysteresis Compensation  

Microsoft Academic Search

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

135

The New P.E.  

ERIC Educational Resources Information Center

Marana Middle School in Tucson, Ariz., scrapped its traditional P.E. program that emphasized team sports and shifted to a program that focuses on lifetime fitness, student choice in activities, and nutrition and health education. The program also includes student leadership development and informal community service. As a result, Marana students…

Vandertie, Joan; Corner, Amy B.; Corner, Kevin J.

2012-01-01

136

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

137

STP Hysteresis Program  

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

138

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

139

Simulation study of hysteresis of argon adsorption in a conical pore and a constricted cylindrical pore.  

PubMed

We present a detailed simulation study of the hysteresis loop in conical pores and in cylindrical pores with periodic constrictions to understand how the non-uniformity of the pore diameter along the pore axis would affect the hysteresis loop. The shape and size of the loop in the conical pores (with and without closed ends) are modified by the cone angle because of the change in the curvature of the menisci at the pore ends. In periodically constricted cylindrical pores, the shape and size of the hysteresis loop are not significantly altered by the pore length or by the presence of a closed end because condensation and evaporation in this type of pore occur in the individual pore sections. Similar hysteresis loops have been found in experimental studies, suggesting that structures of the type modelled here occur in real materials. PMID:23403112

Nguyen, Phuong T M; Do, D D; Nicholson, D

2013-04-15

140

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

141

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

Microsoft Academic Search

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

142

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

143

Compensator design for hysteresis of a stacked PZT actuator using a congruency-based hysteresis model  

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

144

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

Microsoft Academic Search

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

145

Magnetic hysteresis curve influenced by power-semiconductor characteristics in pulse-width-modulation inverter  

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

146

An Accurate Hysteresis Model for Ferroresonance Analysis of a Transformer  

Microsoft Academic Search

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

147

Hysteresis in a swirling jet as a model tornado  

Microsoft Academic Search

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

148

Life prediction of stainless steels by cyclic and stable hysteresis curves  

Microsoft Academic Search

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

149

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

150

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

151

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

152

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

153

Hysteresis of Freedericksz transition in confined light beams  

SciTech Connect

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

154

Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids.  

PubMed

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

155

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

156

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

157

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

158

A generalized Prandtl-Ishlinskii model for characterizing the hysteresis and saturation nonlinearities of smart actuators  

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

159

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

160

A hysteresis effect in photoconductive cadmium selenide and its use in a solid-state image storage device  

Microsoft Academic Search

A brief description of a new hysteresis effect in cadmium selenide photoconductive powder will be given. Photocurrent plotted as a function of voltage has the form of a hysteresis loop, with triggering from low to high currents occurring at a voltage depending on the incident light level. At a suitably chosen voltage, triggering from low to high currents occurs with

F. H. Nicoll

1957-01-01

161

Experimental Implementation of a Model-Based Inverse Filter to Attenuate Hysteresis in an Atomic Force Microscope.  

National Technical Information Service (NTIS)

This paper addresses the development and experimental validation of a model-based, open loop control design for mitigating the frequency-dependent effects of hysteresis in an atomic force microscope (AFM). The models are based on homogenized energy relati...

A. Hatch R. G. Smith T. De

2004-01-01

162

Hysteresis of Two Inequivalent Planar Magnets with Anisotropy  

Microsoft Academic Search

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

163

Wave tunneling and hysteresis in nonlinear junctions.  

PubMed

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

164

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

165

Measurements and modeling of hysteresis in magnetic materials under the action of an orthogonal bias field  

SciTech Connect

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

166

Simulation of magnetic hysteresis in pseudo-single-domain grains of magnetite  

Microsoft Academic Search

Magnetic hysteresis has been simulated in grains of magnetite for the size range 0.1-0.7 microns. This was achieved using an unconstrained three-dimensional micromagnetic model of single grains of magnetite with cubic magnetocrystalline anisotropy. Hysteresis loops were obtained for fields applied along both the easy and hard magnetocrystalline axes. Both discrete (Barkhausen) jumps and gradual changes in the magnetic structure are

W. Williams; David J. Dunlop

1995-01-01

167

Hysteresis and multiple pulsing in a semiconductor disk laser with a saturable absorber  

NASA Astrophysics Data System (ADS)

We report on bistable mode-locking in a semiconductor disk laser. The disk laser mode-locked with a semiconductor saturable absorber is investigated for different designs of the gain medium that allow the hysteresis loop to be controlled. Hysteresis formation in the pulsed regime of a semiconductor oscillator with saturable absorption and unsaturated gain is discussed qualitatively. The laser represents an attractive setup for generation and manipulation of dissipative solitons and observation of their interaction.

Saarinen, Esa J.; Lyytikäinen, Jari; Okhotnikov, Oleg G.

2008-07-01

168

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

169

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

170

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

PubMed

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

171

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

172

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

PubMed

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

173

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

174

Real and causal hysteresis elements.  

PubMed

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

175

Efficiency Wage, Commitment and Hysteresis  

Microsoft Academic Search

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

176

Hysteresis responses of evapotranspiration to meteorological factors at a diel timescale: patterns and causes.  

PubMed

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

177

Hysteresis Responses of Evapotranspiration to Meteorological Factors at a Diel Timescale: Patterns and Causes  

PubMed Central

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

178

Disorder Identification in Hysteresis Data: Recognition Analysis of the Random-Bond-Random-Field Ising Model  

SciTech Connect

An approach for the direct identification of disorder type and strength in physical systems based on recognition analysis of hysteresis loop shape is developed. A large number of theoretical examples uniformly distributed in the parameter space of the system is generated and is decorrelated using principal component analysis (PCA). The PCA components are used to train a feed-forward neural network using the model parameters as targets. The trained network is used to analyze hysteresis loops for the investigated system. The approach is demonstrated using a 2D random-bond-random-field Ising model, and polarization switching in polycrystalline ferroelectric capacitors.

Ovchinnikov, O. S. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Jesse, S.; Kalinin, S. V. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Bintacchit, P.; Trolier-McKinstry, S. [Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2009-10-09

179

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

180

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

181

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

182

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

183

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 N mass/spring/dashpot with deadzone elements. The advantage of this model is that its hysteresis map can be inverted analytically. Second, we investigate the origins of stick-slip friction by developing an asperity-based friction model involving the frictionless contact between a body and a row of rigid, rotating bristles. This model exhibits hysteresis and quasi-stick-slip friction. The hysteretic energy-dissipation mechanism is the sudden release of the pivoted bristles. The discontinuous rotating bristle model is an approximation of the rotating bristle model that exhibits exact stick-slip and hysteresis. We next develop an asperity-based friction model in which the vertical motion of the body leads to the Stribeck effect. The friction model is hysteretic and the energy-dissipation mechanism is the sudden release of the compressed bristles. We show that this bristle model is a generalization of the LuGre model. The final contribution of this dissertation is a framework for relating butterfly-shaped hysteresis maps to simple hysteresis maps, which are typically easier to model and more amenable to control design. In particular, a unimodal mapping is used to transform simple loops to butterfly loops.

Drincic, Bojana

184

Effects of Hysteresis Between Maximum CME Speed Index and Typical Solar Activity Indicators During Cycle 23  

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

185

Segmented shape memory alloy actuators using hysteresis loop control  

Microsoft Academic Search

A new approach to the design and control of shape memory alloy (SMA) actuators is presented. SMA wires are divided into many segments and their thermal states are controlled individually as a group of finite state machines. Instead of driving a current to the entire SMA wire and controlling the wire length based on the analog strain-temperature characteristics, the new

Brian Selden; Kyujin Cho; H. Harry Asada

2006-01-01

186

Asymmetric Magnetization Reversal in Exchange-Biased Hysteresis Loops  

Microsoft Academic Search

Polarized neutron reflectometry is used to probe the in-plane projection of the net-magnetization vector M--> of polycrystalline Fe films exchange coupled to twinned (110) MnF 2 or FeF 2 antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon the orientation of the cooling field with respect to the twinned microstructure of the AF, and whether the applied field is increased

M. R. Fitzsimmons; P. Yashar; C. Leighton; Ivan K. Schuller; J. Nogués; C. F. Majkrzak; J. A. Dura

2000-01-01

187

Hysteresis of transport critical current of high Tc superconductors in strong magnetic fields. Theory  

Microsoft Academic Search

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

188

A current transformer model based on the Jiles-Atherton theory of ferromagnetic hysteresis  

Microsoft Academic Search

The hysteresis loop of the core material in a test current transformer is simulated using the Jiles-Atherton theory. Comparisons are made between recorded and simulated waveforms and it is found necessary to replace the modified Langevin function used by Jiles and Atherton. Using an alternative function described in the paper, good agreement is achieved between test and simulated waveforms

U. D. Annakkage; P. G. McLaren; E. Dirks; R. P. Jayasinghe; A. D. Parker

2000-01-01

189

Tuning size and magnetic thermal hysteresis in a new near room temperature spin crossover compound.  

PubMed

A mononuclear spin crossover compound Fe(AP-Mesal)2, which exhibits spin transitions near room temperature and light induced excited spin state trapping (LIESST) effects at low temperature, was synthesized and substructured in the form of micro- and nanoscaled particles. A thermal hysteresis loop was detected with particle size reduction to microscale and nanoscale. PMID:23633082

Zhang, Li; Wang, Juan-Juan; Xu, Guan-Cheng; Li, Jing; Jia, Dian-Zeng; Gao, Song

2013-06-21

190

Ionically-mediated electromechanical hysteresis in transition metal oxides  

SciTech Connect

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

191

Titration and hysteresis in epigenetic chromatin silencing.  

PubMed

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

192

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

193

Comparative solute–discharge hysteresis analysis for an urbanized and a ‘control basin’ in the Georgia (USA) Piedmont  

Microsoft Academic Search

Solute–discharge hysteresis (C\\/Q) relationships were investigated in an urbanized (Peachtree Creek) and a less-urbanized ‘control’ basin (Sweetwater Creek, SWC) within the Atlanta metropolitan region of the Georgia Piedmont. C\\/Q hysteresis loops for the nine parameters (pH, specific conductance, dissolved silica, calcium, magnesium, sodium, bicarbonate, sulfate and chloride) representative of urban storm flow were almost exclusively characterized by clockwise rotation and

Seth Rose

2003-01-01

194

Texture development and strain hysteresis in a NiTi shape-memory alloy during thermal cycling under load  

Microsoft Academic Search

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

195

Monitoring the hysteresis effects in the strain-stress curve of carbon fiber reinforced laminates by FBG technology  

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

196

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

197

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

198

Thermal Hysteresis Analysis of MEMS Pressure Sensors  

Microsoft Academic Search

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

199

Thermohaline circulation hysteresis: A model intercomparison  

Microsoft Academic Search

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

200

Corneal hysteresis following descemetorhexis with endokeratoplasty  

Microsoft Academic Search

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

201

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

202

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

203

Dynamic hysteresis and scaling behavior for Pb(Zr,Ti)O3 ceramics  

NASA Astrophysics Data System (ADS)

The dynamic hysteresis of Nb-doped Pb(ZrxTi1-x)O3 (PZT, 0.40 ? x ? 0.60) ceramics with different phase structures was investigated as functions of frequency f and electric field amplitude E0. When E0 grows over ˜1.5 times of coercive field Ec, all the loops become well saturated and their scaling relations of hysteresis area ?A? against f and E0 can be expressed with an identical form as ?A??f0.01E00.10 for either tetragonal phase or morphotropic phase, which is in good agreement with our previous result of rhombohedral PZT [Chen et al., J. Appl. Phys. 114, 244101 (2013)]. The results indicate that ferroelectrics with fairly distinct domain structures could have similar dynamic hysteresis and scaling behavior at high-E0 region.

Chen, Xuefeng; Dong, Xianlin; Zhou, Zhiyong; Wang, Junxia; Cao, Fei; Wang, Genshui; Zhang, Hongling

2014-03-01

204

Understanding the Link Between Nanoscale Microstructural Features and Dynamic Hysteresis Phenomena  

SciTech Connect

A Nd–Dy–Fe–B alloy was designed to exhibit high coercivity and optimum loop shapes utilizing a combination of intrinsic and extrinsic alloy design principles. After achieving these initial goals, conventional structural analysis using X-ray and TEM could explain the salient features of the observed hysteresis behavior. However, greater understanding could be gained on the complex dynamic behavior of hysteresis through the exploitation of a new recoil technique that was developed, which focuses on switching field distributions arising from irreversible magnetic behavior. Utilizing this approach, we have successfully linked specific magnetic reversal behavior with distinct magnetic phases that have characteristic microstructural length scales. This new approach may become a powerful tool for the study of the structure–property–hysteresis behavior of hard magnetic materials.

Meacham, Brian Eugene; Branagan, Daniel James; Shield, J. E.

2004-06-01

205

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

206

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

207

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

208

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

209

Adhesion hysteresis of silane coated microcantilevers  

SciTech Connect

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

210

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

211

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

212

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

213

Experimental comparison of some phenomenological hysteresis models in characterizing hysteresis behavior of shape memory alloy actuators  

Microsoft Academic Search

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

214

Modeling of micromagnetic Barkhausen activity using a stochastic process extension to the theory of hysteresis  

SciTech Connect

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

215

Magnetic hysteresis in natural materials. [chondrites, lunar samples and terrestrial rocks  

NASA Technical Reports Server (NTRS)

Magnetic hysteresis loops and the derived hysteresis ratios R sub H and R sub I are used to classify the various natural dilute magnetic materials. R sub I is the ratio of saturation isothermal remanence (I sub R) to saturation (I sub S) magnetization, and R sub H is the ratio of remanent coercive force (H sub R) to coercive force (H sub C). The R sub H and R sub I values depend on grain size, the characteristics of separate size modes in mixtures of grains of high and low coercivity, and the packing characteristics. Both R sub H and R sub I are affected by thermochemical alterations of the ferromagnetic fraction. Hysteresis loop constriction is observed in lunar samples, chondrite meteorites, and thermochemically altered basaltic rocks, and is due to mixtures of components of high and low coercivity. Discrete ranges of R sub H and R sub I for terrestrial and lunar samples and for chondrite meteorites provide for a classification of these natural materials based on their hysteresis properties.

Wasilewski, P. J.

1973-01-01

216

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

217

Hysteresis effects in Bose-Einstein condensates  

SciTech Connect

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

218

PERFORMANCE OF HYSTERESIS PERMANENT MAGNET MOTORS  

Microsoft Academic Search

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

219

Equivalent Circuit Modeling of Hysteresis Motors  

SciTech Connect

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

220

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

221

Disorder-driven first-order phase transformations: A model for hysteresis  

SciTech Connect

Hysteresis loops in some magnetic systems are composed of small avalanches (manifesting themselves as Barkhausen pulses). Hysteresis loops in other first-order phase transitions (including some magnetic systems) often occur via one large avalanche. The transition between these two limiting cases is studied, by varying the disorder in the zero-temperature random-field Ising model. Sweeping the external field through zero at weak disorder, we get one large avalanche with small precursors and aftershocks. At strong disorder, we get a distribution of small avalanches (small Barkhausen effect). At the critical value of disorder where a macroscopic jump in the magnetization first occurs, universal power-law behavior of the magnetization and of the distribution of (Barkhausen) avalanches is found. This transition is studied by mean-field theory, perturbative expansions, and numerical simulation in three dimensions.

Dahmen, K.; Kartha, S.; Krumhansl, J.A.; Roberts, B.W.; Sethna, J.P.; Shore, J.D. (Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501 (United States))

1994-05-15

222

The influence of laminar separation and transition on low Reynolds number airfoil hysteresis  

NASA Technical Reports Server (NTRS)

An experimental study of the Lissaman 7769 and Miley MO6-13-128 airfoils at low chord Reynolds numbers is presented. Although both airfoils perform well near their design Reynolds number of about 600,000, they each produce a different type of hysteresis loop in the lift and drag forces when operated below chord Reynolds numbers of 300,000. The type of hysteresis loop was found to depend upon the relative location of laminar separation and transition. The influence of disturbance environment and experimental procedure on the low Reynolds number airfoil boundary layer behavior is also presented. The use of potential flow solutions to help predict how a given airfoil will behave at low Reynolds numbers is also discussed.

Mueller, T. J.

1984-01-01

223

Loop simulations.  

PubMed

Loop modeling is crucial for high-quality homology model construction outside conserved secondary structure elements. Dozens of loop modeling protocols involving a range of database and ab initio search algorithms and a variety of scoring functions have been proposed. Knowledge-based loop modeling methods are very fast and some can successfully and reliably predict loops up to about eight residues long. Several recent ab initio loop simulation methods can be used to construct accurate models of loops up to 12-13 residues long, albeit at a substantial computational cost. Major current challenges are the simulations of loops longer than 12-13 residues, the modeling of multiple interacting flexible loops, and the sensitivity of the loop predictions to the accuracy of the loop environment. PMID:22323223

Totrov, Maxim

2012-01-01

224

Transport, hysteresis and avalanches in artificial spin ice systems  

SciTech Connect

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

225

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

226

Parent Effectiveness Training (P.E.T.): Criticisms and Caveats.  

ERIC Educational Resources Information Center

Criticizes Parent Effectiveness Training (P.E.T.) for its emphasis on one-sided techniques in the parent-child relationship and its tendency to reduce complex problems to simplistic formulas. P.E.T.'s central metaphor of parent-as-therapist is identified and found wanting. Issues have applicability to the parent education movement in general.…

Doherty, William J.; Ryder, Robert G.

1980-01-01

227

Isothermal magnetization of samples with stable Preisach function: A survey of hysteresis, remanence, and rock magnetic parameters  

Microsoft Academic Search

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

228

Low-power optical bistability and hysteresis in the laser system with absorbing nanosuspension.  

PubMed

We demonstrate an optical bistability in a laser system with incoherent optical feedback and a nanosuspension as a nonlinear element. The optical transfer function is shown to exhibit a hysteresis loop for the light power in the range of a few milliwatts. It has been found that the optical bistability relies on the incoherent optical feedback and thermal defocusing nonlinear optical response of the nanosuspension. PMID:24784112

Pobegalov, George; Agruzov, Peter; Ilichev, Igor; Shamray, Alexander

2014-05-01

229

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

230

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.

231

Dynamic magnetic hysteresis behavior and dynamic phase transition in the spin-1 Blume-Capel model  

NASA Astrophysics Data System (ADS)

The nature (time variation) of response magnetization m( wt) of the spin-1 Blume-Capel model in the presence of a periodically varying external magnetic field h( wt) is studied by employing the effective-field theory (EFT) with correlations as well as the Glauber-type stochastic dynamics. We determine the time variations of m( wt) and h( wt) for various temperatures, and investigate the dynamic magnetic hysteresis behavior. We also investigate the temperature dependence of the dynamic magnetization, hysteresis loop area and correlation near the transition point in order to characterize the nature (first- or second-order) of the dynamic transitions as well as obtain the dynamic phase transition temperatures. The hysteresis loops are obtained for different reduced temperatures and we find that the areas of the loops are decreasing with the increasing of the reduced temperatures. We also present the dynamic phase diagrams and compare the results of the EFT with the results of the dynamic mean-field approximation. The phase diagrams exhibit many dynamic critical points, such as tricritical (•), zero-temperature critical (Z), triple (TP) and multicritical (A) points. According to values of Hamiltonian parameters, besides the paramagnetic (P), ferromagnetic (F) fundamental phases, one coexistence or mixed phase region, (F+P) and the reentrant behavior exist in the system. The results are in good agreement with some experimental and theoretical results.

Deviren, Bayram; Keskin, Mustafa

2012-03-01

232

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

233

Negative hysteresis effect observed during calibration of the US Bureau of Mines borehole deformation gauge  

SciTech Connect

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

234

Analysis of a hysteresis motor with overexcitation  

SciTech Connect

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

235

Behavior of dissolved and total phosphorus concentration and stream discharge: The form of hysteresis during storm events  

NASA Astrophysics Data System (ADS)

The forms, rotational patterns and trends of hysteretic loops of dissolved and total phosphorus were investigated in the watershed of a New York City drinking water reservoir. We evaluated two biogeochemical parameters summarizing the changes in solute concentrations and the overall dynamics of each hysteretic loop and seven hydrological parameters that characterize the hydrograph formation of particular storm events. The objectives of this study are: (1) to examine whether the characteristics of solute hysteretic loops monitored during the summer, winter and spring seasons followed a consistent and recurring pattern, (2) to identify hydrological parameters which could potentially influence features of dissolved and total phosphorus hysteresis. Relationships between hysteresis features and hydrological parameters at the watershed outlet were explored using multivariate redundancy analysis (RDA).

Pradhanang, S. M.; Samal, N. R.; Pierson, D. C.; Schneiderman, E. M.; Zion, M. S.

2013-12-01

236

Tracking Control of Shape-Memory-Alloy Actuators Based on Self-Sensing Feedback and Inverse Hysteresis Compensation  

PubMed Central

Shape memory alloys (SMAs) offer a high power-to-weight ratio, large recovery strain, and low driving voltages, and have thus attracted considerable research attention. The difficulty of controlling SMA actuators arises from their highly nonlinear hysteresis and temperature dependence. This paper describes a combination of self-sensing and model-based control, where the model includes both the major and minor hysteresis loops as well as the thermodynamics effects. The self-sensing algorithm uses only the power width modulation (PWM) signal and requires no heavy equipment. The method can achieve high-accuracy servo control and is especially suitable for miniaturized applications.

Liu, Shu-Hung; Huang, Tse-Shih; Yen, Jia-Yush

2010-01-01

237

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

238

Topological hysteresis in stripe domain structures  

Microsoft Academic Search

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

239

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

240

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

241

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

242

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

243

Dynamical aspects of the adsorption hysteresis phenomenon  

Microsoft Academic Search

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

244

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

245

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

246

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

247

Geometric Hysteresis of Alveolated Ductal Architecture  

PubMed Central

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

248

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

249

Hysteresis Loss as a Measure of Metal-Rubber Adhesion  

Microsoft Academic Search

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

250

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

Microsoft Academic Search

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

251

Quantum Hydrodynamic Simulation of Hysteresis in the Resonant Tunneling Diode  

Microsoft Academic Search

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

252

Characterizing piezoscanner hysteresis and creep using optical levers and a reference nanopositioning stage  

SciTech Connect

A method using atomic force microscope (AFM) optical levers and a reference nanopositioning stage has been developed to characterize piezoscanner hysteresis and creep. The piezoscanner is fixed on a closed-loop nanopositioning stage, both of which have the same arrangement on each axis of the three spatial directions inside the AFM-based nanomanipulation system. In order to achieve characterization, the optical lever is used as a displacement sensor to measure the relative movement between the nanopositioning stage and the piezoscanner by lateral tracking a well-defined slope with the tapping mode of the AFM cantilever. This setup can be used to estimate a piezoscanner's voltage input with a reference displacement from the nanopositioning stage. The hysteresis and creep were accurately calibrated by the method presented, which use the current setup of the AFM-based nanomanipulation system without any modification or additional devices.

Xie, H.; Regnier, S. [Institute of Intelligent System and Robotics, University of Pierre and Marie Curie/CNRS UMR 7222, 4 Place Jussieu, 75005 Paris (France); Rakotondrabe, M. [Department of Automatic Control and Micro-Mechatronic Systems, FEMTO-ST Institute, CNRS UMR 6174-UFC/ENSMM/UTBM, 24, Rue Alain Savary, 25000 Besancon (France)

2009-04-15

253

Hysteresis and acoustic emission as non-destructive measures of the fatigue process in metals  

NASA Astrophysics Data System (ADS)

Metal fatigue is a result of a cumulative damage process due to repeated cyclic loading which causes premature and unpredictable failure. It is a complicated metallurgical process at the microscopic level which is difficult to accurately explain or model. Despite the complexities, fatigue analysis methods have been developed and are being developed to facilitate fatigue damage assessment and the prediction of fatigue life. This research project is concerned with the behavior of metals subjected to cyclic loading carried to failure. The purpose of this investigation is to develop a relationship between hysteresis loss, hysteresis loop drift, strain amplitudes, and the number of cycles to failure and to correlate this phenomenological description of the fatigue process with mesoscopic observables such as acoustic emission and stress-induced magnetization.

Guralnick, S. A.

1995-03-01

254

Hysteresis and return-point memory in colloidal artificial spin ice systems.  

PubMed

Using computer simulations, we investigate hysteresis loops and return-point memory for artificial square and kagome spin ice systems by cycling an applied bias force and comparing microscopic effective spin configurations throughout the hysteresis cycle. Return-point memory loss is caused by motion of individual defects in kagome ice or of grain boundaries in square ice. In successive cycles, return-point memory is recovered rapidly in kagome ice. Memory is recovered more gradually in square ice due to the extended nature of the grain boundaries. Increasing the amount of quenched disorder increases the defect density but also enhances the return-point memory since the defects become trapped more easily. PMID:23005762

Libál, A; Reichhardt, C; Olson Reichhardt, C J

2012-08-01

255

Nature of dislocation hysteresis losses and nonlinear effect in lead at high vibration amplitudes  

SciTech Connect

The nature of the dislocation hysteresis was established and changes in this hysteresis were determined by investigating the dependence of the dislocation-induced absorption of ultrasound (coefficient ..cap alpha..) on the amplitude of ultrasound epsilon-c/sub 0/ in single crystals of pure lead and of lead containing Tl and Sn impurities. The investigation was carried out in a wide range of epsilon-c/sub 0/ under superconducting transition conditions. In the superconducting (s) state both pure Pb and that doped with T1 exhibited a maximum in the dependence ..cap alpha..(epsilon-c/sub 0/) at high values of epsilon-c/sub 0/; on transition to the normal (n) state this maximum changed to a plateau. This provided a direct proof of a change in the static nature of the dislocation hysteresis to the dynamic process because of an increase in the coefficient of the electron drag of dislocations. Estimates were obtained of the range of lengths of dislocation loops: 2.4 x 10/sup -4/ cmhysteresis occurred both in the normal and superconducting states. In the range of amplitudes above that of the maximum and at the beginning of the plateau all single crystals exhibited a rise of ..cap alpha.. on increase of epsilon-c/sub 0/ in the superconducting and normal states; this rise was due to nonlinear effects observed in the case of strong bending of L/sub N/ loops. An analysis was made of the amplitude dependence of the losses associated with this effect. The results were in good agreement with the experimental data.

Lomakin, V.V.; Pal-Val, L.N.; Platkov, V.Y.; Roshchupkin, A.M.

1982-11-01

256

Sorption hysteresis of benzene in charcoal particles.  

PubMed

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

257

Effects of matching network on the hysteresis during E and H mode transitions in argon inductively coupled plasma  

SciTech Connect

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

258

Stability of dithered non-linear systems with backlash or hysteresis  

NASA Technical Reports Server (NTRS)

A study is conducted of the effect of dither on the nonlinear element of a single-input single-outout feedback system. Nonlinearities are considered with memory (backlash, hysteresis), in the feedforward loop; a dither of a given amplitude is injected at the input of the nonlinearity. The nonlinearity is followed by a linear element with low-pass characteristic. The stability of the dithered system and an approximate equivalent system (in which the nonlinearity is a smooth function) are compared. Conditions on the input and on the dither frequency are obtained so that the approximate-system stability guarantees that of the given hysteretic system.

Desoer, C. A.; Shahruz, S. M.

1986-01-01

259

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

260

Doubly excited 3P(e) resonant states in Ps(-)  

NASA Technical Reports Server (NTRS)

Doubly excited 3P(e) resonant states in Ps(-) are calculated using a method of complex-coordinate rotation. Resonance parameters (both resonance positions and widths) for doubly excited states associated with the n = 2, 3, 4, 5, and 6 thresholds of positronium atoms are evaluated using elaborate Hylleraas-type functions. In addition to ten Feshbach-type resonances lying below various Ps thresholds, three shape resonances were identified, one each lying above the n = 2, 4, and 6 Ps thresholds. It is further noted that the energy levels for the present 3P(e) states are nearly degenerate with respect to the previously calculated 1P(0) states. Such a symmetric character suggests that the highly and doubly excited Ps(-), similar to its counterpart in H(-), would exhibit rovibrational behaviors analogous to those of XYX triatomic molecules.

Ho, Y. K.; Bhatia, A. K.

1992-01-01

261

Loop space  

NASA Astrophysics Data System (ADS)

Several topics in the loop-space formulation of non-Abelian gauge theories are considered. The basic objects dealt with are the unrenormalized dimensionally regularized gauge-invariant loop functions W(Cig, ?), where Ci is a set of loops, g is the unrenormalized coupling constant, and ? is the deviation from four space-time dimensions. The renormalization-group equations satisfied by the corresponding renormalized loop functions are derived and, using asymptotic freedom, used to determine the exact behavior of the functions when the length L of the loops approaches zero. The result is (-lnL?)a(?), where ? is the subtraction mass and ? represents the cusp and cross-point angles of the loops. The function a(?) is exactly computable and several examples are given. The equivalent result may be stated as the exact behavior of the renormalization-constant matrix Zij(?, gR, ?) for ?-->0 with fixed renormalized coupling constant gR, or as the exact behavior of the unrenormalized loop function for ?-->0 and gR fixed. It is shown next that the W(Cig, ?) satisfy dimensionally regularized Makeenko-Migdal equations in all orders of perturbation theory. The proof makes detailed use of dimensional regularization, Becchi-Rouet-Stora symmetry, gauge-field combinatorics, and properties of the area functional derivative of path-ordered multiple line integrals. Doubt is cast on the existence of such useful equations when other regularizations are used or when renormalization is performed. The Mandelstam constraints are considered next. Among other things, it is shown that the loop-function renormalization may be performed such that the renormalized functions satisfy a constraint which has the same form as the unrenormalized constraint i=1(N+1)?aiW(Ci)=0, for the U(N) gauge group. The paper concludes with illustrations of how observable matrix elements of physical (color singlet, quark bilinear) flavor currents may be expressed in terms of loop functions. Among other topics discussed in the paper are the N-->? limit, two-dimensional QCD, and normalization conditions on the renormalized loop functions.

Brandt, R. A.; Gocksch, A.; Sato, M.-A.; Neri, F.

1982-12-01

262

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

263

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

264

Hysteresis measurement of individual multilayered Fe-Ga/Cu nanowires using magnetic force microscopy  

NASA Astrophysics Data System (ADS)

We have investigated nano-scale magnetic structures to learn how magnetic behaviors differ from what is observed in bulk materials. In this study, we have measured the magnetic hysteresis of individual multilayered nanowire using a magnetic force microscopy (MFM). The nanowires were composed of low-aspect ratio segments of iron-gallium (Galfenol, Fe80Ga20) and copper layers. Individual wires were released from nano-porous anodized aluminum oxide (AAO) templates and separated from other nanowires to avoid significant interactions between nearby nanowires. In this experiment, structures with aspects ratios c/a of ~3 were studied. Different MFM phase magnitudes in response to the interaction of magnetic film coated MFM tips and Fe-Ga/Cu nanowire were observed as a function of applied external magnetic field (-850 Oe < H < 850 Oe). Amplitude differences between bright and dark responses in MFM images were used to demonstrate hysteresis. Coercivity measured was about 125 Oe, which is almost same as the coercivity value (~150 Oe) of a nanowire array measured with a vibrating sample magnetometer (VSM). When fields are applied perpendicular to the nanowires, the hysteresis loops sheared, indicating that the easy axis is along the nanowire axis. Remanence magnetizations of an individual nanowire and a nanowire array were compared to demonstrate inter-wire magnetostatic dipolar interaction.

Jin Park, Jung; Reddy, Madhukar; Stadler, Bethanie J. H.; Flatau, Alison B.

2013-05-01

265

Optical hysteresis in liquid crystals with helicoidal distributed feedback  

SciTech Connect

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

266

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

267

Corneal hysteresis in patients with dry eye  

PubMed Central

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

268

A Investigation of the Dielectric and Hysteresis Properties of Plzt Ferroelectric and Multilayer Composite Thin Films.  

NASA Astrophysics Data System (ADS)

The dielectric and hysteresis properties of ferroelectric and multilayer composite thin films were investigated. PLZT ferroelectrics were produced in bulk ceramic and thin film form from the same acetate precursor solutions in order to compare their electrical and physical properties. Bulk ceramics were hot pressed from chemically coprecipitated powders, and thin films were fabricated by spin and dip coating on Ag and Pt-coated Si substrates. Internal film stress from thermal expansion mismatch between films and substrates was found to contribute to differences in electrical properties and Curie temperatures between the thin film and bulk materials as were interface layer effects, grain size and mechanical clamping from the substrates. Rapid thermal processing (RTP) of PLZT thin films using an automated spin coat reactor was found to improve thin film dielectric and hysteresis properties as well as enhance perovskite phase formation, induce preferred (110) and (111) orientations, decrease grain size and increase microstructural uniformity. RTP films were compared with manually spin coated thin films with conventional furnace pyrolysis (CFP) in order to isolate the effects of heating rate from deposition technique. Heating rates of at least 70^circC per second were obtained by RTP versus 35^circC per second for CFP. The development of composite thin films further optimized PLZT thin film properties. Improved antiferroelectric -to-ferroelectric domain switching with decreased ferroelectric coercive field, increased induced polarization with decreased coercivity and polarization remanence for relaxor-type composites and increased hysteresis loop squareness for ferroelectric memory materials were among the advances compared with films of homogeneous PLZT composition. Experimental dielectric and hysteresis properties were described by a series capacitor model consisting of the linear and nonlinear properties of the individual composite components.

Dausch, David Edward

1995-01-01

269

Deformable mirrors for open-loop adaptive optics  

NASA Astrophysics Data System (ADS)

We characterize the performance of deformable mirrors for use in open-loop regimes. This is especially relevant for Multi Object Adaptive Optics (MOAO), or for closed-loop schemes that require improved accuracies. Deformable mirrors are usually characterized by standard parameters, such as influence functions, linearity, hysteresis, etc. We show that these parameters are insufficient for characterizing open-loop performance and that a deeper analysis of the mirror's behavior is then required. The measurements on the deformable mirrors were performed in 2007 on the AO test bench of the Meudon observatory, SESAME.

Kellerer, A.; Vidal, F.; Gendron, E.; Hubert, Z.; Perret, D.; Rousset, G.

2012-07-01

270

Magnetization hysteresis studies in Sm1-xGdxAl2 alloys  

NASA Astrophysics Data System (ADS)

SmAl2 (Tc ˜ 125 K, ?sat= 0.23 ?B/f.u.) is known to exhibit magnetic compensation when doped with Gd (< 3 at.%). In such stoichiometries though the magnetization gets closer to zero, there exists a large spin polarization. This makes such materials attractive candidates for applications. We have performed detailed magnetization hysteresis and other studies in the series Sm1-xGdxAl2. In x=0.02 alloy, the loops are shifted (notion of exchange bias) along negative H-axis for temperatures just above Tcomp , and along positive H-axis for temperatures T < Tcomp. We argue that the change in the sign of exchange bias is due to the magnetic contribution of conduction electron polarization as well as that of local magnetic moments reversing the signs. At Tcomp the width of the hysteresis loop collapses. In the given series, one can set up the system in either spin-surplus or orbital-surplus state and control the exchange bias field. The compositions with 0.03 <= x < 0.06 do not exhibit zero cross over of magnetization and remain spin surplus. Our various studies and analysis shall be presented.

Vaidya, U. V.; Venkatesh, S.; Rakhecha, V. C.; Ramakrishnan, S.; Grover, A. K.

2009-03-01

271

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

PubMed

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

272

Application of magnetomechanical hysteresis modeling to magnetic techniques for monitoring neutron embrittlement and biaxial stress  

SciTech Connect

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

273

Modulation effect of transverse currents on the switch and hysteresis characteristics in blue bronze Rb 0.3MoO 3  

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

274

A new dynamic model of hysteresis in harmonic drives  

Microsoft Academic Search

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

275

Corneal hysteresis following descemetorhexis with endokeratoplasty: early results.  

PubMed

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

276

Impact of relative permeability hysteresis on geological CO2 storage  

Microsoft Academic Search

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

277

International Workshop on Multi-Rate Processes and Hysteresis  

Microsoft Academic Search

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

278

PREFACE: International Workshop on Multi-Rate Processes and Hysteresis  

Microsoft Academic Search

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

279

Energy-based hysteresis model for magnetostrictive transducers  

Microsoft Academic Search

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

280

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

281

A permanent magnet hysteresis hybrid synchronous motor for electric vehicles  

Microsoft Academic Search

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

282

Starting and synchronization of permanent magnet hysteresis motors  

Microsoft Academic Search

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

283

Transient performance analysis for permanent magnet hysteresis synchronous motor  

Microsoft Academic Search

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

284

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

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

285

Starting and synchronization of permanent magnet hysteresis motors  

Microsoft Academic Search

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

286

A permanent magnet hysteresis hybrid motor drive for electric vehicles  

Microsoft Academic Search

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

287

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

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

288

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

289

Windmill speed limiting system utilizing hysteresis  

SciTech Connect

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

290

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

291

Hysteresis in pressure-driven DNA denaturation.  

PubMed

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

292

Hysteresis in Pressure-Driven DNA Denaturation  

PubMed Central

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

293

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

294

Hysteresis behavior during reactive magnetron sputtering of Al{sub 2}O{sub 3} using a rotating cylindrical magnetron  

SciTech Connect

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

295

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

296

Control of Hysteresis in Smart Actuators. Part 1. Modeling, Parameter Identification, and Inverse Control.  

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

297

Hysteresis and creep modeling and compensation for a piezoelectric actuator using a fractional-order Maxwell resistive capacitor approach  

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

298

Loop Algorithm  

NASA Astrophysics Data System (ADS)

The loop algorithm for the world-line quantum Monte Carlo method on quantum lattice models is presented. After introducing the path integral representation that maps a quantum model to a classical one, we describe the continuous imaginary time limit, cluster algorithm, and the rejection free scheme, which are the major improvements on the quantum Monte Carlo technique during the last decades. By means of the loop algorithm, one can simulate various unfrustrated quantum lattice models of millions of sites at extremely low temperatures with absolute accuracy, being free from the critical and fine-mesh slowing down and the Suzuki-Trotter discretization error. We also discuss some technical aspects of the algorithm such as effective implementation and parallelization.

Todo, Synge

299

Testing of a Loop Heat Pipe Subjected to Variable Accelerating Forces  

NASA Technical Reports Server (NTRS)

This paper presents viewgraphs of the functionality of a loop heat pipe that was subjected to variable accelerating forces. The topics include: 1) Summary of LHP (Loop Heat Pipe) Design Parameters; 2) Picture of the LHP; 3) Schematic of Test Setup; 4) Test Configurations; 5) Test Profiles; 6) Overview of Test Results; 7) Start-up; 8) Typical Start-up without Temperature Overshoot; 9) Start-up with a Large Temperature Overshoot; 10) LHP Operation Under Stationary Condition; 11) LHP Operation Under Continuous Acceleration; 12) LHP Operation Under Periodic Acceleration; 13) Effects of Acceleration on Temperature Oscillation and Hysteresis; 14) Temperature Oscillation/Hysteresis vs Spin Rate; and 15) Summary.

Ku, Jentung; Ottenstein, Laura; Kaya, Tarik; Rogers, Paul; Hoff, Craig

2000-01-01

300

Hysteresis and mode transition in terms of electron energy distribution function for an inductively coupled argon discharge  

SciTech Connect

The electron energy distribution function (EEDF) with respect to the hysteresis loop of an inductively coupled argon discharge has been studied experimentally. Contrary to H mode, knowledge of EEDF in E mode is still limited, and an elaborate EEDF measurement with regard to power and pressure for this mode is presented. The Langmuir probe measurements reveal two regions with distinct EEDFs in E mode, which might be a critical missing factor in explaining the unresolved hysteresis and mode transition phenomenon of inductive discharges. Furthermore, a Poynting vector representation has been used to explain the power coupling in an inductive discharge, where (azimuthal) e{sub {theta}} component is proposed to be dominant in the 'hybrid mode' region.

Singh, S. V. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2008-04-15

301

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

302

Drag force measurement: A means for determining hysteresis loss  

SciTech Connect

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

303

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

304

Hysteresis and nonlinear elasticity in rocks  

SciTech Connect

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

305

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

306

On the question of hysteresis in Hall magnetohydrodynamic reconnection  

SciTech Connect

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

307

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

308

Hysteresis as a Marker for Complex, Overlapping Landscapes in Proteins  

PubMed Central

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

309

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

310

Sensitivity and hysteresis properties of A-WO3, Ta2O5, and A-Si:H gate ion-sensitive field-effect transistors  

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

Influence of applied tensile stress on the hysteresis curve and magnetic domain structure of grain-oriented Fe–3%Si steel  

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

312

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

313

Thermal-expansion hysteresis in graphite\\/glass composites  

Microsoft Academic Search

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 ..-->.. 25°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

314

Hysteresis as an implicit prior in tactile spatial decision making.  

PubMed

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

315

Stabilization of supercooled fluids by thermal hysteresis proteins.  

PubMed Central

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

316

Generalized hysteresis current controller for three-level inverter topologies  

Microsoft Academic Search

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

317

Hysteresis in Thin-Film Rechargeable Lithium Batteries  

SciTech Connect

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

318

Transient performance analysis for permanent-magnet hysteresis synchronous motor  

Microsoft Academic Search

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

319

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

320

Modeling and characterization for polarization hysteresis of ferroelectric polymers  

Microsoft Academic Search

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

321

Perceptual hysteresis in the judgment of auditory pitch shift.  

PubMed

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

322

Synchronous neural networks of nonlinear threshold elements with hysteresis.  

PubMed Central

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

323

Adhesion hysteresis and friction at nanometer and micrometer lengths  

SciTech Connect

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

324

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

325

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

326

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

Microsoft Academic Search

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

327

Ferromagnetism, hysteresis and enhanced heat dissipation in assemblies of superparamagnetic nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, we develop theoretical frameworks to explain the emergence of ferromagnetism in suspensions and agglomerates of superparamagnetic (SPM) nanoparticles. In the limit of strong anisotropy, the super moments can be treated as a collection of two-state Ising spins. When adequate in number, they interact via dipole-dipole coupling to produce a dipolar field and subsequently a permanent dipole moment. As a result, this effectual ferromagnet exhibits hysteresis on the application of an oscillating magnetic field yielding heat dissipation that is several orders of magnitude larger than in a paramagnet. Using our frameworks, we provide a design for a magnetite-blood suspension that yields heat dissipation in the mW range. Its important physical application is in remedial procedures for destroying tumor and cancer cells. We are also able to explain many experiments reporting manifestations of ferromagnetism in the form of hysteresis loops, return point memory and large heat dissipation in suspensions and aggregates of SPM nanoparticles. Our frameworks can be used to manipulate heat dissipation in variety of combinations of particles and their embedding mediums. They impart a basis to the often used ad-hoc methodologies in this subject.

Singh, Vanchna; Banerjee, Varsha

2012-12-01

328

An undulation theory for condensation in open end slit pores: critical hysteresis temperature & critical hysteresis pore size.  

PubMed

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

329

Surface magnetic anisotropy of CoFe2O4 nanoparticles with a giant low-temperature hysteresis  

NASA Astrophysics Data System (ADS)

Ferrimagnetic nanoparticles of CoFe2O4 about 4-16 nm in diameter were synthesized by pyrolysis of a mixture of Fe and Co acetylacetonates. The field dependences of magnetization and hysteresis loops were investigated in magnetic fields up to 4000 kA/m at various temperatures from 4.2 to 500 K. A considerable contribution, positive or negative depending on the temperature, of ``surface'' anisotropy to the effective magnetic anisotropy of the nanoparticles was observed. A correlation was found between the magnetic properties that represent the specificity of small particles, namely, between ``surface'' anisotropy, magnetization, and high-field susceptibility.

Mozul', K. A.; Ol'khovik, L. P.; Sizova, Z. I.; Bludov, A. N.; Pashchenko, V. A.; Baumer, V. N.; Vashchenko, V. V.; Kolosov, M. O.; Kryshtal', A. P.; Prodanov, M. F.

2013-04-01

330

Surface and hysteresis properties of lipid interphases composed by head group substituted phosphatidylethanolamines.  

PubMed

This work analyzes the surface properties of PE-containing membranes modified at the head group region by the addition of methyl and ethyl residues at or near the amine group. These residues alter the lipid-lipid and lipid-water interactions by changes in the hydrogen bonding capability and the charge density of the amine group thus affecting the electrostatic interaction. The results obtained by measuring the dipole potential, the zeta potential, the area per lipid and the compressibility properties allow to conclude that the H-bonding capability prevails in the lipid-lipid interaction. The non polar groups attached to the C2-carbon of the ethanolamine chain introduces a steric hindrance against compression and increases the dipole potential. The analysis of areas suggests that lipids with methylated head groups have a much larger compressibility at expense of the elimination of hydration water, which is congruent with the broader extent of the hysteresis loop. PMID:24099791

Salcedo, C L; Bouchet, A M; Nazareno, M A; Disalvo, E A; Frias, M A

2014-01-01

331

Hydrological hysteresis in catchments and its value for assessing process consistency in conceptual models  

NASA Astrophysics Data System (ADS)

While most hydrological models reproduce the general flow dynamics, they frequently fail to adequately mimic system internal processes. In particular, the relationship between storage and discharge, which often follows annual hysteretic patterns in shallow hard-rock aquifers, is rarely considered in modelling studies. One main reason is that catchment storage is difficult to measure and another one is that objective functions are usually based on individual variables time series (e.g. the discharge). This reduces the ability of classical procedures to assess the relevance of the conceptual hypotheses associated with models. We analyzed the annual hysteric patterns observed between stream flow and water storage both in the saturated and unsaturated zones of the hillslope and the riparian zone of a headwater catchment in French Brittany (ORE AgrHys). The saturated zone storage was estimated using distributed shallow groundwater levels and the unsaturated zone storage using several moisture profiles. All hysteretic loops were characterized by a hysteresis index. Four conceptual models, previously calibrated and evaluated for the same catchment, were assessed with respect to their ability to reproduce the hysteretic patterns. The observed relationship between stream flow, saturated, and unsaturated storages led to identify four hydrological periods and emphasized a clearly distinct behaviour between riparian and hillslope groundwaters. Although all the tested models were able to produce an annual hysteresis loop between discharge and both saturated and unsaturated storage, integration of a riparian component led to overall improved hysteretic signatures, even if some misrepresentation remained. Such systems-like approach is likely to improve model selection.

Fovet, O.; Ruiz, L.; Hrachowitz, M.; Faucheux, M.; Gascuel-Odoux, C.

2014-05-01

332

Water Stream "Loop-the-Loop"  

ERIC Educational Resources Information Center

Discusses the design of a modified loop-the-loop apparatus in which a water stream is used to illustrate centripetal forces and phenomena of high-velocity hydrodynamics. Included are some procedures of carrying out lecture demonstrations. (CC)

Jefimenko, Oleg

1974-01-01

333

Simulation of a vector hysteresis measurement system taking hysteresis into account by the vector Preisach model  

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

334

The origin of noise and hysteresis in permalloy ring-core fluxgate sensors  

NASA Astrophysics Data System (ADS)

in permalloy ring-core fluxgate sensors a single phenomenon may cause both fluxgate noise and magnetic hysteresis. It also provides an explanation for Barkhausen noise, remanence and coercivity. It can also resolve the "domain nucleation problem." in the unmagnetized state a high-quality permalloy foil takes a domain structure generally referred to as "stripe domains," which present at the free surface as parallel, uniformly spaced domain walls bounding regions of alternating 'in' and 'out' leakage flux, and domain walls crossing the entire thickness of the foil. The leakage flux is a requirement of the random orientation, grain-by-grain, of magnetic easy axes' angles with respect to the foil free surface, and creates a free space field with a magnetostatic energy cost. This together with domain wall energy determines an energy budget to be minimized. Throughout the magnetization cycle the free surface domain pattern remains essentially unchanged, due to the extreme magnetostatic energy cost such a change would elicit. Thus domain walls are 'pinned' to free surfaces. As the fluxgate core is driven to saturation, domain walls pinned at the free surfaces first bulge then reconnect to form a new domain configuration this author has called "channel domains", which are attached to free surfaces. Energy released during the domain wall reconnection manifests as Barkhausen noise, while the reconnection itself manifests as a Barkhausen jump. The approach to saturation now continues as reversible channel domain compression. Driving the permalloy into deep saturation will compress the channel domains to arbitrarily small thickness, but will not cause them to denucleate. Returning from saturation the channel domain structure will survive through zero drive H, thus explaining remanence. The Barkhausen jumps being irreversible, exothermic events are sources of fluxgate noise. It is also the case that fluxgate signal power is proportional to B-H loop curvature, that is to the second derivative of B. The degree to which Barkhausen jumps coincide with loop curvature is a measure of fluxgate noise that accompanies fluxgate signal. B-H loops with significant curvature beyond the open hysteresis loop may be used to advantage to acquire fluxgate signal with much reduced fluxgate noise.

Narod, Barry

2013-04-01

335

Enhanced ferroelectric loop asymmetry of lead zirconate titanate thin films under nanoindentation  

NASA Astrophysics Data System (ADS)

The effect of mechanical stress on the local switching behavior and hysteresis properties of Pb(Zr,Ti)O3 and Mn-doped Pb(Zr,Ti)O3 ferroelectric thin films has been studied using spherical nanoindentation. A conductive WC-Co cermet indenter tip of 500 ?m nominal radius was employed in a modified nanoindentation system to allow the simultaneous application of driving voltage and mechanical loading, and consequently to collect the ferroelectric charge developed on thin films without a top electrode. Instrumented progressive indentation caused an enhancement of hysteresis loop deformations. The charge released versus applied voltage (Q-V) hysteresis loops gradually shifted along the voltage axis with increasing indentation force. Also, an enhanced vertical shift and hysteresis gap of the Q-V loops was observed. The parameter of horizontal loop asymmetry (?) increased almost linearly with the force by an increment of about (0.4-0.5)×10-3/100 mN with a 50 V peak drive voltage and a 50 Hz sinusoidal wave form. The effect of nanoindentation on polarization reversal in thin ferroelectric films is suggested to result from a variation in residual stress state, asymmetric distribution of charged defects, and asymmetric lattice distortion produced by the inhomogeneous indentation stress field.

Koval, V.; Reece, M. J.; Bushby, A. J.

2007-01-01

336

Nucleation and hysteresis of vapor-liquid phase transitions in confined spaces: Effects of fluid-wall interaction  

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

337

Hysteresis loops of individual Co nanostripes measured by magnetic force microscopy  

PubMed Central

High-resolution magnetic imaging is of utmost importance to understand magnetism at the nanoscale. In the present work, we use a magnetic force microscope (MFM) operating under in-plane magnetic field in order to observe with high accuracy the domain configuration changes in Co nanowires as a function of the externally applied magnetic field. The main result is the quantitative evaluation of the coercive field of the individual nanostructures. Such characterization is performed by using an MFM-based technique in which a map of the magnetic signal is obtained as a function of both the lateral displacement and the magnetic field.

2011-01-01

338

Standard Properties of Seignette Electric Crystals with Rectangular Loop of Dielectric Hysteresis.  

National Technical Information Service (NTIS)

The investigations have shown, that Seignetto-electric materials are suitable for the obtainment of reference voltages. Seignetto-electric bismuth titanate-flakes have a series of additional advantages, because bismuth titanate appears to be a crystal ins...

I. S. Zheludev D. A. Tambovtsev B. P. Terent'ev

1965-01-01

339

Self consistent generalized model for the calculation of minor loop excursions in the theory of hysteresis.  

National Technical Information Service (NTIS)

In the previous work it has been shown that the magnetization curves of a wide range of ferromagnetic materials can be calculated from a simple theory which invokes a constant energy loss per unit change in magnetization. The energy loss, which is therefo...

D. C. Jiles

1992-01-01

340

Capillary rise in a microchannel of arbitrary shape and wettability: hysteresis loop.  

PubMed

Capillary rise in an asymmetric microchannel, in which both contact angle (wettability) and open angle (geometry) can vary with position, is investigated based on free-energy minimization. The integration of the Young-Laplace equation yields the general force balance between surface tension and gravity. The former is surface tension times the integration of cos ?(u) along the contact line, where ?(u) depicts the local difference between contact angle and open angle. The latter comes from the total volume right underneath the meniscus. For the same channel height, multiple solutions can be obtained from the force balance. However, the stable height of capillary rise must satisfy stability analysis. Several interesting cases have been studied, including short capillary, truncated cone, hyperboloid, and two different plates. As the tube length is smaller than Jurin's height, the angle of contact will be tuned to fulfill the force balance. While only one stable state is seen for divergent channels, two stable states can be observed for convergent channels. Three regimes can be identified for the plot of the stable height of capillary rise against the channel height. The higher height dominates in the short channel regime, while the lower height prevails in the tall channel regime. However, both solutions are stable in the intermediate regime. Surface Evolver simulations and experiments are performed to validate our theoretical predictions. Our results offer some implications for water transport to the tops of tall trees. A small bore at the uppermost leaf connected to a larger xylem conduit corresponds to a convergent channel, and two stable heights are possible. The slow growth of the tree can be regarded as a gradual rise of the convergent channel. Consequently, the stable height of capillary rise to the top of a tall tree can always be achieved. PMID:23171321

Wang, Zhengjia; Chang, Cheng-Chung; Hong, Siang-Jie; Sheng, Yu-Jane; Tsao, Heng-Kwong

2012-12-11

341

Stress dependence of ferromagnetic hysteresis loops for two grades of steel  

Microsoft Academic Search

Residual stress is an essential input into calculations of the remaining life of operational plant. However, many life predictions are inherently conservative because measurements of the absolute stress are unavailable. The magnetic properties of material are sensitive to stress, and in this paper, the magnetic properties (at maximum magnetisation, at remnance, and at the coercive field) of two grades of

K. J. Stevens

2000-01-01

342

Predicting loss in magnetic steels under arbitrary induction waveform and with minor hysteresis loops  

Microsoft Academic Search

We have studied ways of predicting power losses in soft magnetic laminations for generic time dependence of the periodic magnetic polarization J(t). We found that, whatever the frequency and the induction waveform, the loss behavior can be quantitatively assessed within the theoretical framework of the statistical loss model. The prediction requires a limited set of preemptive experimental data, depending on

Edoardo Barbisio; Fausto Fiorillo; Carlo Ragusa

2004-01-01

343

Experiments on snap buckling, hysteresis and loop formation in twisted rods  

Microsoft Academic Search

We give the results of large deflection experiments involving the bending and twisting of 1 mm diameter nickel-titanium alloy\\u000a rods, up to 2 m in length. These results are compared to calculations based on the Cosserat theory of rods. We present details\\u000a of this theory, formulated as a boundary value problem. The mathematical boundary conditions model the experimental setup.\\u000a The

V. G. A. Goss; G. H. M. van der Heijden; J. M. T. Thompson; S. Neukirch

2005-01-01

344

INSIDE THE HYSTERESIS LOOP: MULTIPLICITY OF INTERNAL STATES IN CONFINED FLUIDS. (R825959)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

345

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

346

Hysteresis in the production of force by larval Dipteran muscle.  

PubMed

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

347

Real-time inverse hysteresis compensation of piezoelectric actuators with a modified Prandtl-Ishlinskii model.  

PubMed

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

348

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

349

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

350

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

351

Hidden hysteresis - population dynamics can obscure gene network dynamics  

PubMed Central

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

352

Modelling eddy currents and hysteresis in a transformer laminate  

SciTech Connect

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

353

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

354

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

355

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

356

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

357

Molecular Origin and Functional Consequences of Digital Signaling and Hysteresis During Ras Activation in Lymphocytes  

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

358

Fast flux locked loop  

DOEpatents

A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.

Ganther, Jr., Kenneth R. (Olathe, KS); Snapp, Lowell D. (Independence, MO)

2002-09-10

359

OPE for super loops  

NASA Astrophysics Data System (ADS)

We extend the Operator Product Expansion for Null Polygon Wilson loops to the Mason-Skinner-Caron-Huot super loop dual to non MHV gluon amplitudes. We explain how the known tree level amplitudes can be promoted into an infinite amount of data at any loop order in the OPE picture. As an application, we re-derive all one loop NMHV six gluon amplitudes by promoting their tree level expressions. We also present some new all loops predictions for these amplitudes.

Sever, Amit; Vieira, Pedro; Wang, Tianheng

2011-11-01

360

The preprocessed doacross loop  

NASA Technical Reports Server (NTRS)

Dependencies between loop iterations cannot always be characterized during program compilation. Doacross loops typically make use of a-priori knowledge of inter-iteration dependencies to carry out required synchronizations. A type of doacross loop is proposed that allows the scheduling of iterations of a loop among processors without advance knowledge of inter-iteration dependencies. The method proposed for loop iterations requires that parallelizable preprocessing and postprocessing steps be carried out during program execution.

Saltz, Joel H.; Mirchandaney, Ravi

1990-01-01

361

Analyzing hysteresis behavior of capacitance-voltage characteristics of IZO/C60/pentacene/Au diodes with a hole-transport electron-blocking polyterpenol layer by electric-field-induced optical second-harmonic generation measurement  

NASA Astrophysics Data System (ADS)

By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we analyzed hysteresis behavior of capacitance-voltage (C-V) characteristics of IZO/polyterpenol (PT)/C60/pentacene/Au diodes, where PT layer is actively working as a hole-transport electron-blocking layer. The EFISHG measurement verified the presence of interface accumulated charges in the diodes, and showed that a space charge electric field from accumulated excess electrons (holes) that remain at the PT/C60 (C60/pentacene) interface is responsible for the hysteresis loop observed in the C-V characteristics.

Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Bazaka, Kateryna; Jacob, Mohan V.

2013-05-01

362

A dead-beat adaptive hysteresis current control  

Microsoft Academic Search

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

363

Hysteresis in a simple model of currency substitution  

Microsoft Academic Search

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

364

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

365

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

366

Probabilistic counter updates for predictor hysteresis and stratification  

Microsoft Academic Search

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

367

Dynamic Contact Angles and Hysteresis under Electrowetting-on-Dielectric  

PubMed Central

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

368

Differential hysteresis modeling of a shape memory alloy wire actuator  

Microsoft Academic Search

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

369

Iterative feedforward compensation of hysteresis in piezo positioners  

Microsoft Academic Search

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

370

Novel Hysteresis Current Controller for Active Power Filter  

Microsoft Academic Search

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

371

Hysteresis heating based induction bonding of composite materials  

Microsoft Academic Search

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

372

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

373

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

Microsoft Academic Search

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

374

Three-level inverter based shunt active power filter using generalized hysteresis current control method  

Microsoft Academic Search

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

375

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

Microsoft Academic Search

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

376

Temperature dependence on the hysteresis of aSi:H TFT and Elimination of the hysteresis effect on OLED current for AMOLED Display  

Microsoft Academic Search

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

377

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

378

Climate Feedback Loops  

NSDL National Science Digital Library

This is the seventh of nine lessons in the 'Visualizing and Understanding the Science of Climate Change' website. This lesson addresses climate feedback loops and how these loops help drive and regulate Earth's unique climate system.

Researchers, King'S C.

379

Large lithium loop experience  

Microsoft Academic Search

An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters

R. Kolowith; T. J. Owen; J. D. Berg; J. M. Atwood

1981-01-01

380

Hysteresis and Kinetic Effects During Liquid-Solid Transitions  

SciTech Connect

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

381

Hysteresis in the Underdamped Driven Frenkel-Kontorova Model  

SciTech Connect

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

382

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

383

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

384

Contact angle hysteresis on textured surfaces with nanowire clusters.  

PubMed

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

385

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

386

Sediment Hysteresis Patterns In Singapore Urban Residential Lined Channels  

Microsoft Academic Search

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

387

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

388

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

389

Resistive hysteresis in BiFeO 3 thin films  

Microsoft Academic Search

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

390

An analysis of metal fatigue based on hysteresis energy  

Microsoft Academic Search

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

391

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

392

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

393

Hysteresis properties of titanomagnetites: Grain-size and compositional dependence  

Microsoft Academic Search

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

394

Applications of hysteresis switching in parameter adaptive control  

Microsoft Academic Search

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

395

Congruency-based hysteresis models for transient simulation  

Microsoft Academic Search

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

396

Modeling and adaptive inverse control of hysteresis and creep in ionic polymer-metal composite actuators  

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

397

Wettability hysteresis and its implications for DNAPL source zone distribution.  

PubMed

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

398

Chen Integrals, Generalized Loops and Loop Calculus  

NASA Astrophysics Data System (ADS)

We use Chen iterated line integrals to construct a topological algebra {A}p of separating functions on the group of loops L?p. {A}p has a Hopf algebra structure which allows the construction of a group structure on its spectrum. We call this topological group the group of generalized loops widetilde {{L} {M}p } Then we develop a loop calculus, based on the end point and area derivative operators, providing a rigorous mathematical treatment of the early heuristic ideas of Gambini, Trias and also Mandelstam, Makeenko and Migdal. Finally, we define a natural action of the “pointed” diffeomorphism group Diffp(?) on widetilde {{L} {M}p }, and consider a variational derivative which allows the construction of homotopy invariants. This formalism is useful for constructing a mathematical theory of loop representation of gauge theories and quantum gravity.

Tavares, J. N.

399

Optical bistability in nonlinear system with two loops of feedback  

NASA Astrophysics Data System (ADS)

A model of nonlinear optical system surrounded by two loops of feedback is investigated. The cell with the vapor of rubidium ? - type atoms is taken in the capacity of nonlinear element. Two modes of near-resonant electromagnetic field interacting with the cell are involved in the feedback. Two-dimensional optical bistability domain in location of input field intensities is obtained and dependence of its form and magnitude from the system parameters (photon detunings, feedback factor etc.) is investigated. "Input -output" relations corresponding to different trajectories in the bistability domain are obtained. Cross-hysteresis is studied.

Miroshnichenko, George P.; Trifanov, Alexander I.

2010-09-01

400

The origin of noise and magnetic hysteresis in crystalline permalloy ring-core fluxgate sensors  

NASA Astrophysics Data System (ADS)

6-81.3 Mo permalloy, developed in the 1960s for use in high performance ring-core fluxgate sensors, remains the state-of-the-art for permalloy-cored fluxgate magnetometers. The magnetic properties of 6-81.3, namely magnetocrystalline and magnetoelastic anisotropies and saturation induction are all optimum in the Fe-Ni-Mo system. In such polycrystalline permalloy fluxgate sensors a single phenomenon may cause both fluxgate noise and magnetic hysteresis, explain Barkhausen jumps, remanence and coercivity, and avoid domain denucleation. The phenomenon, domain wall reconnection, is presented as part of a theoretical model. In the unmagnetized state a coarse-grain high-quality permalloy foil ideally forms stripe domains, which present at the free surface as parallel, uniformly spaced domain walls that cross the entire thickness of the foil. Leakage flux "in" and "out" of alternating domains is a requirement of the random orientation, grain-by-grain, of magnetic easy axes' angles with respect to the foil free surface. Its magnetostatic energy together with domain wall energy determines an energy budget to be minimized. Throughout the magnetization cycle the free surface domain pattern remains essentially unchanged, due to the magnetostatic energy cost such a change would elicit. Thus domain walls are "pinned" to free surfaces. Driven to saturation, domain walls first bulge then reconnect via Barkhausen jumps to form a new domain configuration this author has called "channel domains", that are attached to free surfaces. The approach to saturation now continues as reversible channel domain compression. Driving the permalloy deeper into saturation compresses the channel domains to arbitrarily small thickness, but will not cause them to denucleate. Returning from saturation the channel domain structure will survive through zero H, thus explaining remanence. The Barkhausen jumps being irreversible exothermic events are sources of fluxgate noise, powered by the energy available from domain wall reconnection. A simplified domain energy model can then provide a predictive relation between ring core magnetic properties and fluxgate sensor noise power. Four properties are predicted to affect noise power, two of which, are well known: saturation total magnetic flux density and magnetic anisotropy. The two additional properties are easy axes alignment and foil thickness. Flux density and magnetic anisotropy are primary magnetic properties determined by an alloy's chemistry and crystalline lattice properties. Easy axes alignment and foil thickness are secondary, geometrical properties related to an alloy's polycrystalline fabric and manufacture. Improvements to fluxgate noise performance can in principle be achieved by optimizing any of these four properties in such a way as to minimize magnetostatic energy. Fluxgate signal power is proportional to B-H loop curvature (d2B/dH2). The degree to which Barkhausen jumps coincide with loop curvature is a measure of noise that accompanies fluxgate signal. B-H loops with significant curvature beyond the open hysteresis loop may be used to advantage to acquire fluxgate signal with reduced noise.

Narod, B. B.

2014-06-01

401

Application of a variable direction hysteresis minimization approach in describing the central nervous system pharmacodynamic effects of alfentanil in rabbits.  

PubMed

The relationship between the concentration of a drug and its pharmacologic effect is of central interest in pharmacodynamics. Various compartmental and noncompartmental methods have been proposed for elucidating this relationship when the plasma drug concentration and effects are both measured. Although the relationship between drug input and the pharmacologic effect is equally useful, it has not received as much attention. A system analysis hysteresis minimization pharmacodynamic method was developed to describe the central nervous system effects of alfentanil in rabbits. The spectral edge frequency (SEF) was used as the effect measure and the infusion rate as the pharmacokinetic variable. The sigmoid Emax and cubic polynomial representations of the transduction relationship were investigated in modeling the collapsed hysteresis loop. The results indicated that alfentanil has a relatively rapid biophase equilibration time (t50 = 6 min). Both the sigmoid Emax and cubic polynomial transduction relationships were equally effective in describing the observed effect data and gave similar predictions. The proposed approach has the advantage of not assuming a specific compartmental structure for the pharmacokinetic-pharmacodynamic link. A particular advantage of the method is that no functional relationship is assumed a priori for the transduction relationship, and errors in both regression variables are considered in the optimization. The system analysis pharmacodynamic approach assumes linear disposition pharmacokinetics, an instantaneous and time-invariant transduction, and that inductive effects like tolerance or sensitization do not develop significantly in the time frame studied. PMID:8207680

Modi, N B; Veng-Pedersen, P

1994-03-01

402

Interactions of Cations with RNA Loop-Loop Complexes  

PubMed Central

RNA loop-loop interactions are essential in many biological processes, including initiation of RNA folding into complex tertiary shapes, promotion of dimerization, and viral replication. In this article, we examine interactions of metal ions with five RNA loop-loop complexes of unique biological significance using explicit-solvent molecular-dynamics simulations. These simulations revealed the presence of solvent-accessible tunnels through the major groove of loop-loop interactions that attract and retain cations. Ion dynamics inside these loop-loop complexes were distinctly different from the dynamics of the counterion cloud surrounding RNA and depend on the number of basepairs between loops, purine sequence symmetry, and presence of unpaired nucleotides. The cationic uptake by kissing loops depends on the number of basepairs between loops. It is interesting that loop-loop complexes with similar functionality showed similarities in cation dynamics despite differences in sequence and loop size.

Singh, Abhishek; Sethaphong, Latsavongsakda; Yingling, Yaroslava G.

2011-01-01

403

Adaptive neural tracking control for a class of nonstrict-feedback stochastic nonlinear systems with unknown backlash-like hysteresis.  

PubMed

This paper considers the problem of adaptive neural control of stochastic nonlinear systems in nonstrict-feedback form with unknown backlash-like hysteresis nonlinearities. To overcome the design difficulty of nonstrict-feedback structure, variable separation technique is used to decompose the unknown functions of all state variables into a sum of smooth functions of each error dynamic. By combining radial basis function neural networks' universal approximation capability with an adaptive backstepping technique, an adaptive neural control algorithm is proposed. It is shown that the proposed controller guarantees that all the signals in the closed-loop system are four-moment semiglobally uniformly ultimately bounded, and the tracking error eventually converges to a small neighborhood of the origin in the sense of mean quartic value. Simulation results further show the effectiveness of the presented control scheme. PMID:24808040

Huanqing Wang; Bing Chen; Kefu Liu; Xiaoping Liu; Chong Lin

2014-05-01

404

Cochlear hysteresis: Observation with low-frequency modulated distortion product otoacoustic emissions  

NASA Astrophysics Data System (ADS)

Low-frequency modulation of distortion product otoacoustic emissions (DPOAEs) can be used to estimate a nonlinear transducer function (fTr) of the cochlea. From gerbils, DPOAEs were measured while presenting a high-level bias tone. Within one period of the bias tone, the magnitudes of the cubic difference tone (CDT, 2f1-f2) demonstrated two similar modulation patterns (MPs) each resembled the absolute value of the third derivative of the fTr. The center peaks of the MPs occurred at positive sound pressures for rising in bias pressure or loading of the cochlear transducer, and more negative pressures while decreasing bias amplitude or unloading. The corresponding fTr revealed a sigmoid-shaped hysteresis loop with counterclockwise traversal. Physiologic indices that characterized the double MP varied with primary level. A Boltzmann-function-based model with negative damping as a feedback component was proposed. The model was able to replicate the experimental results. Model parameters that fit to the CDT data indicated higher transducer gain and more prominent feedback role at lower primary levels. Both physiologic indices and model parameters suggest that the cochlear transducer dynamically changes its gain with input signal level and the nonlinear mechanism is a time-dependent feedback process.

Bian, Lin; Linhardt, Erin E.; Chertoff, Mark E.

2004-05-01

405

Wilson loops @ 3-loops in special kinematics  

NASA Astrophysics Data System (ADS)

We obtain a compact expression for the octagon MHV amplitude/Wilson loop at 3 loops in planar mathcal{N} = {4} SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.

Heslop, Paul; Khoze, Valentin V.

2011-11-01

406

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

407

A study of hysteresis in the K ID -å relation  

Microsoft Academic Search

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

408

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

409

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

410

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

411

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

412

Anomalous hysteresis properties of iron films deposited on liquid surfaces  

SciTech Connect

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

413

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

414

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

415

Experimental investigation on operating instability of a dual compensation chamber loop heat pipe  

Microsoft Academic Search

The operating instability of a dual compensation chamber loop heat pipe (DCC-LHP) including temperature hysteresis, reverse\\u000a flow and temperature oscillation is described and explained in this paper. Test results indicate that the steady state operating\\u000a temperature under the variable conductance mode is not the same during the power cycle tests with the same heat load, and\\u000a it is lower during

JianTing Feng; GuiPing Lin; LiZhan Bai

2009-01-01

416

Magnetoresistance hysteresis in granular HTSCs as a manifestation of the magnetic flux trapped by superconducting grains in YBCO + CuO composites  

SciTech Connect

Hysterestic behavior of the magnetoresistance of granular HTSCs and its interaction with the magnetic hysteresis are studied by measuring magnetoresistance R(H) and critical current I{sub c}(H) of composites formed by HTSC Y{sub 0.75}Lu{sub 0.25}Ba{sub 2}Cu{sub 3}O{sub 7} and CuO. A network of Josephson junctions is formed in such composites, in which the nonsuperconducting component plays the role of barriers between HTSC grains. Hysteretic dependences R(H) of magnetoresistance are studied in a wide range of transport current density j and are analyzed in the framework of the two-level model of a granular superconductor, in which dissipation takes place in the Josephson medium and the magnetic flux can be pinned both in grains and in the Josephson medium. The interrelation between the hysteresis of critical current I{sub c}(H) and the evolution of the hysterestic dependence R(H) of the magnetoresistance upon transport current variation is demonstrated experimentally. The effect of the magnetic past history on the hysteretic behavior of R(H) and the emergence of a segment with a negative magnetoresistance are analyzed. It is shown for the first time that the R(H) dependences are characterized by a parameter that is independent of the transport current, viz., the width of the R(H) hysteresis loop.

Balaev, D. A., E-mail: smp@iph.krasn.ru; Gokhfeld, D. M.; Dubrovskii, A. A.; Popkov, S. I.; Shaikhutdinov, K. A.; Petrov, M. I. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Branch (Russian Federation)

2007-12-15

417

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

Microsoft Academic Search

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

418

Analysis of Power Magnetic Components With Nonlinear Static Hysteresis: Proper Orthogonal Decomposition and Model Reduction  

Microsoft Academic Search

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

419

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

Microsoft Academic Search

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

420

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

421

Characterization of strain-induced martensite phase in austenitic stainless steel using a magnetic minor-loop scaling relation  

SciTech Connect

We propose a combined magnetic method using a scaling power-law rule and initial permeability in magnetic minor hysteresis loops for characterization of ferromagnetic {alpha}{sup '} martensites in austenitic stainless steel. The scaling power law between the hysteresis loss and remanence is universal, being independent of volume fraction of strain-induced {alpha}{sup '} martensites. A coefficient of the power law largely decreases with volume fraction, while the initial permeability linearly increases, reflecting a change in the morphology and quantity of martensites, respectively. The present method is highly effective for integrity assessment of austenitic stainless steels because of the sensitivity and extremely low measurement field.

Kobayashi, Satoru; Saito, Atsushi; Takahashi, Seiki; Kamada, Yasuhiro; Kikuchi, Hiroaki [NDE and Science Research Center, Faculty of Engineering, Iwate University, Ueda 4-3-5, Morioka 020-8551 (Japan)

2008-05-05

422

Hysteresis analysis for the permanent magnet assisted synchronous reluctance motor by coupled FEM and Preisach modelling  

SciTech Connect

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

423

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

424

Hysteresis of soft joints embedded with fluid-filled microchannels  

PubMed Central

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

425

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

426

Hysteresis and saturation effects with the ALS lattice magnets  

SciTech Connect

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

427

Falling Loop Model  

NSDL National Science Digital Library

The EJS Falling Loop Model shows a conducting loop falling out of a uniform magnetic field. Users can change the size and orientation of the loop. If Ejs is installed, right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item allows for editing of the model. The Falling Loop model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_FallingLoop.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Cox, Anne

2009-09-24

428

Career of the Month: An Interview with Aquaculture Veterinarian Roy P.E. Yanong  

NSDL National Science Digital Library

Did you know that fish have doctors too? Although this may sound "fishy", it's true! In this issue's Career of the Month column, you'll meet fish doctor Roy P.E. Yanong, an Aquaculture Veterinarian, and discover this intriguing career in the process.

Sullivan, Megan

2005-07-01

429

Applying the Bradley-Terry-Luce Method to P-E Fit  

ERIC Educational Resources Information Center

This study attempted to increase the size of the correlation between person-environment (P-E) fit and job satisfaction by rescaling the instrumentation of the Theory of Work Adjustment using the Bradley-Terry-Luce method and a probability-based fit index. This approach worked as well as, but failed to outperform, the currently used…

Eggerth, Donald E.

2004-01-01

430

Loops, polytopes and splines  

NASA Astrophysics Data System (ADS)

We uncover an unexpected connection between the physics of loop integrals and the mathematics of spline functions. One loop integrands are Laplace transforms of splines. This clarifies the geometry of the associated loop integrals, since a n-node spline has support on a n-vertex polyhedral cone. One-loop integrals are integrals of splines on a hyperbolic slice of the cone, yielding polytopes in AdS space. Splines thus give a geometrical counterpart to the rational function identities at the level of the integrand. Spline technology also allows for a clear, simple, algebraic decomposition of higher point loop integrals in lower dimensional kinematics in terms of lower point integrals — e.g. an hexagon integral in 2d kinematics can be written as a sum of scalar boxes. Higher loops can also be understood directly in terms of splines — they map onto spline convolutions, leading to an intriguing representation in terms of hyperbolic simplices integrated over other hyperbolic simplices. We finish with speculations on the interpretation of one-loop integrals as partition functions, inspired by the use of splines in counting points in polytopes.

Paulos, Miguel F.

2013-06-01

431

Application of magnetomechanical hysteresis modeling to magnetic techniques for monitoring neutron embrittlement and biaxial stress. Progress report, June 1991--December 1991  

SciTech Connect

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

432

Systematics of high temperature perturbation theory: The two-loop electron self-energy in QED  

NASA Astrophysics Data System (ADS)

In order to investigate the systematics of the loop expansion in high temperature gauge theories beyond the leading order hard thermal loop (HTL) approximation, we calculate the two-loop electron proper self-energy ? in high temperature QED. The two-loop bubble diagram of ? contains a linear infrared divergence. Even if regulated with a nonzero photon mass M of order of the Debye mass, this infrared sensitivity implies that the two-loop self-energy contributes terms to the fermion dispersion relation that are comparable to or even larger than the next-to-leading order (NLO) contributions of the one-loop ?. Additional evidence for the necessity of a systematic restructuring of the loop expansion comes from the explicit gauge-parameter dependence of the fermion damping rate at both one and two loops. The leading terms in the high temperature expansion of the two-loop self-energy for all topologies arise from an explicit hard-soft factorization pattern, in which one of the loop integrals is hard (p?T), nested inside a second loop integral which is soft (0?p?T for real parts; p?eT for imaginary parts). There are no hard-hard contributions to the two-loop ? at leading order at high T. Provided the same factorization pattern holds for arbitrary ? loops, the NLO high temperature contributions to the electron self-energy come from ?-1 hard loops factorized with one soft loop integral. This hard-soft pattern is a necessary condition for the resummation over ? to coincide with the one-loop self-energy calculated with HTL dressed propagators and vertices, and to yield the complete NLO correction to ? at scales ˜eT, which is both infrared finite and gauge invariant. We employ spectral representations and the Gaudin method for evaluating finite temperature Matsubara sums, which facilitates the analysis of multiloop diagrams at high T.

Mottola, Emil; Szép, Zsolt

2010-01-01

433

Large lithium loop experience  

SciTech Connect

An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters include coolant temperatures to 430/sup 0/C and flow to 0.038 m/sup 3//s (600 gal/min). Performance of the main pump, vacuum system, and control system is discussed. Unique test capabilities of the ELS are also discussed.

Kolowith, R.; Owen, T.J.; Berg, J.D.; Atwood, J.M.

1981-10-01

434

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

Microsoft Academic Search

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

435

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

Microsoft Academic Search

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

436

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

Microsoft Academic Search

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

437

Large melting point hysteresis of Ge nanocrystals embedded inSiO2  

SciTech Connect

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

438

Analysis and microprocessor implementation of field oriented control for permanent magnet hysteresis synchronous motor  

Microsoft Academic Search

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

439

Hysteresis analysis for the permanent magnet assisted synchronous reluctance motor by coupled FEM and Preisach modelling  

Microsoft Academic Search

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

440

Controlling the response of color tunable poly(N-isopropylacrylamide) microgel-based etalons with hysteresis.  

PubMed

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

441

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

442

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

443

Theory and simulation of angular hysteresis on planar surfaces.  

PubMed

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

444

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

445

Hysteresis in flow patterns in annular swirling jets  

SciTech Connect

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

446

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

447

The thermodynamic origin of hysteresis in insertion batteries.  

PubMed

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

448

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

449

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

450

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

451

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

452

Causes and implications of colloid and microorganism retention hysteresis.  

PubMed

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

453

Hot giant loop holography  

SciTech Connect

We argue that there is a phase transition in the expectation value of the Polyakov loop operator in the large N limit of the high temperature deconfined phase of N=4 Yang-Mills theory on a spatial S{sup 3}. It occurs for the large completely symmetric representation of the SU(N) symmetry group. We speculate that this transition is reflected in the D-branes which are the string theory duals of giant loops.

Grignani, Gianluca [Dipartimento di Fisica, Universita di Perugia, INFN Sezione di Perugia, Via A. Pascoli, 06123 Perugia (Italy); Karczmarek, Joanna L.; Semenoff, Gordon W. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

2010-07-15

454

Bifurcations of cuspidal loops  

Microsoft Academic Search

A cuspidal loop 0951-7715\\/10\\/6\\/001\\/img5 for a planar vector field X consists of a homoclinic orbit 0951-7715\\/10\\/6\\/001\\/img6 through a singular point p, at which X has a nilpotent cusp. This is the simplest non-elementary singular cycle (or graphic) in the sense that its singularities are not elementary (i.e. hyperbolic or semihyperbolic). Cuspidal loops appear persistently in three-parameter families of planar vector

Freddy Dumortier; Robert Roussarie; Jorge Sotomayor

1997-01-01

455

Thrown for a Loop  

NSDL National Science Digital Library

In this lesson, students begin to focus on the torque associated with a current carrying loop in a magnetic field. Students are prompted with example problems and use diagrams to visualize the vector product. In addition, students learn to calculate the energy of this loop in the magnetic field. Several example problems are included and completed as a class. A homework assignment is also attached as a means of student assessment.

VU Bioengineering RET Program, School of Engineering,

456

Electromagnetic inductive models for the loop-loop flaring interaction  

Microsoft Academic Search

The solar corona is a highly structured medium. Coronal loops, which trace closed magnetic field lines, are the primary structural elements. These loops are the evolving non-stationary objects growing up and changing their shape. Complex dynamics of the loops together with action of possible under-photospheric dynamo mechanisms cause the majority of coronal magnetic loops to be very likely as the

M. Khodachenko; H. Rucker

2003-01-01

457

Episodic Coronal Loop Heating  

NASA Astrophysics Data System (ADS)

Coronal loop temperatures are known to be of a few millions degrees but the nature of the energy source remains as a longstanding fundamental problem for solar (and stellar) physics. Observations of solar atmospheric plasma show clear evidence of frequent very localised heating events, which may be statistically responsible for heating of the solar upper atmosphere. One heating theory indicates that these micro-scale events are driven by localized magnetic field reconnection. In this paper, we present the results of numerical calculations that describe the response of the coronal plasma to small-scale heating pulses in a magnetic loop. In particular, we study the effects of energy input pulses injected randomly near the two footpoints of a semi-circular loop. We have found that increasing the elapsing time between successive pulses, the overall loop temperature decreases. When a critical elapsing time is reached the loop can no longer be maintained at typical coronal temperatures. These features have some support from SOHO-CDS observations of coronal loops which seem to undergo strong variability especially in active regions of the solar atmosphere (Kjeldseth-Moe &Brekke, 1998). We also have found that successive random pulses can statistically maintain the average plasma temperature at typical coronal values. Due to the randomness of the heat injections, the resulting temperature profiles show thermal bumps that could be connected to intermittent behaviour in the transition region and the low corona.

Mendoza-Briceño, C. A.; Erdélyi, R.

2004-01-01

458

HYDRA: A LightWeight, SCORM-Based P2P e-Learning Architecture  

Microsoft Academic Search

Many P2P frameworks for e-learning and knowledge management are being proposed. Most of these frameworks provide generic interfaces to support multiple information providers. This results in an implementation overhead. In this paper we present a lightweight P2P e-learning architecture which uses a fast native XML database to allow basic query, retrieval and download services using SCORM metadata. Like EDUTELLA, this

Imran A. Zualkernan; Dom Parser

2005-01-01

459

Parallelization Approaches for Hardware Accelerators - Loop Unrolling Versus Loop Partitioning  

Microsoft Academic Search

State-of-the-art behavioral synthesis tools barely have high-level transformations in order to achieve highly parallelized\\u000a implementations. If any, they apply loop unrolling to obtain a higher throughput. In this paper, we employ the PARO behavioral\\u000a synthesis tool which has the unique ability to perform both loop unrolling or loop partitioning. Loop unrolling replicates\\u000a the loop kernel and exposes the parallelism for

Frank Hannig; Hritam Dutta; Jürgen Teich

2009-01-01

460

N Reactor secondary loop contamination  

Microsoft Academic Search

N Reactor primary loop water circulates entirely within Zone 1 and the piping is, therefore, heavily shielded. Secondary loop piping crosses the Zone 1 boundaries into areas which may be unshielded and accessible during reactor operation. The leakage of primary loop water to the secondary side of the cooling loop permits contaminated fluid to leave the shielded area. It becomes

Stepnewski

1963-01-01

461

Shape of cosmic string loops  

SciTech Connect

Complicated cosmic string loops will fragment until they reach simple, nonintersecting ('stable') configurations. Through extensive numerical study we characterize these attractor loop shapes including their length, velocity, kink, and cusp distributions. We find that an initial loop containing M harmonic modes will, on average, split into 3M stable loops. These stable loops are approximately described by the degenerate kinky loop, which is planar and rectangular, independently of the number of modes on the initial loop. This is confirmed by an analytic construction of a stable family of perturbed degenerate kinky loops. The average stable loop is also found to have a 40% chance of containing a cusp. We examine the properties of stable <