Note: This page contains sample records for the topic hysteresis from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

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

2

Digital Hysteresis Circuit.  

National Technical Information Service (NTIS)

Noise induced hunting is eliminated in successive ranged digital/analog converter bias correction circuits by means of a digital hysteresis circuit. The digital hysteresis circuit comprehends a first up/down counter that counts to its extremums from a pre...

S. Morrison

1978-01-01

3

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

4

Mathematical models of hysteresis  

NASA Astrophysics Data System (ADS)

Progress is reported in 7 areas: development of vector Preisach-type models of hysteresis; modeling of rotational hysteretic losses; experimental testing of generalized vector Preisach models of hysteresis; development of Preisach-type models for after-effect; analytical investigation of penetration of electromagnetic fields into superconductors with gradual resistive transitions; computation of magnetic fields in hysteretic media; and development of new techniques for calculating 3-D eddy current problems.

Mayergoyz, I. D.

1993-09-01

5

Hysteresis and fatigue  

SciTech Connect

Energy dissipation associated with damage of materials is irreversible and loading cycles are accompanied by the evolution of heat. The relation between energy dissipation and loading therefore exhibits a memory dependence or hysteresis. Conversely, sustained hysteresis is a necessary condition for fatigue and is related to the rate of damage accumulation. Standards for estimating fatigue life are partially based on the Manson-Coffin relations between the width of stress strain hysteresis loops and the number of loading cycles required to produce failure in test pieces. In the present study, experimental and theoretical results demonstrate that this relation can be extended into a simple phenomenological description of fatigue that directly links total hysteresis energy dissipation, the cumulation of material damage, and the average number of loading cycles leading to failure. Analogies between the incremental collapse of structures and the inception and organization of damage in materials are used to aid understanding of the detailed features of hysteresis. Scanning tunneling microscope measurements of the threshold of mechanical irreversibility and acoustic emission patterns are used to detect the evolution of hysteresis at the microscopic level. 61 refs., 14 figs., 1 tab.

Erber, T. (Univ. of California, Los Angeles (United States)); Guralnick, S.A.; Michels, S.C. (Illinois Institute of Technology, Chicago (United States))

1993-06-01

6

Mathematical models of hysteresis  

SciTech Connect

The ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema (not the entire input variations) leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. The origin of such tools can be traced back to the landmark paper of Preisach. Their research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. During the past four years, the study has been by and large centered around the following topics: (1) further development of Scalar and vector Preisach-type models of hysteresis; (2) experimental testing of Preisach-type models of hysteresis; (3) development of new models for viscosity (aftereffect) in hysteretic systems; (4) development of mathematical models for superconducting hysteresis in the case of gradual resistive transitions; (5) software implementation of Preisach-type models of hysteresis; and (6) development of new ideas which have emerged in the course of the research work. The author briefly describes the main scientific results obtained in the areas outlined above.

NONE

1998-08-01

7

[Mathematical models of hysteresis  

SciTech Connect

The research described in this proposal is currently being supported by the US Department of Energy under the contract Mathematical Models of Hysteresis''. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories''. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

Mayergoyz, I.D.

1991-01-01

8

Hysteresis and terrestrial hydrology  

NASA Astrophysics Data System (ADS)

An examination of the physics of the land phase of the hydrological cycle shows that the most important non-linearities occur in the unsaturated zone of the soil. These have been studied by Dooge, his co-workers, and others, using switched boundary conditions applied to the one-dimensional form of Richards equation, modelling a one-square meter column of bare soil. Soil water responds to alternating wet and dry periods. Each period starts with a surface flux in or out of the soil that is set by atmospheric conditions. The moisture profile at the end of one period provides the initial condition for the next period. Within each period, a switch from atmosphere control to soil control may occur if the atmospheric conditions are strong enough and if they last for sufficient time. We refer to these times as the "time to ponding" in the case of infiltration of rain, and the "time to stage-two drying" in the case of evaporation. Consequently, there are two sets of switches in the computational clock: an outer pair always switching between wet and dry periods, and an inner pair switching intermittently from atmosphere control to soil control. Their effect has been studied on simplified forms of Richards equation. However the strongly non-linear, hysteretic property of the soil moisture characteristic is always ignored. It is more pronounced for sands than for clays. The presence of macropores changes, but does not eliminate, the hysteresis. The GRIZZLY database brings together a wide range of data sets on soil hysteresis. For many years the description of hysteresis in soils was largely based on Poulovassilis' application of the independent domain theory. Significant progress has since been made on the mathematical properties of hysteresis and its incorporation into models of unsaturated flow in porous media. The purpose of this presentation is to summarise these advances and to examine their implications for hydrology from the pedon (1 meter) scale to the catchment scale starting with the simplest models.

O Kane, J. P.; Pokrovski, A.; Kreichi, P.; Haverkamp, R.

2003-04-01

9

Kinematic theory of piezoelectric hysteresis  

Microsoft Academic Search

A biasing voltage applied across a bonded piezoelectric plate causes a transverse deflection. For slowly varying voltages, the displacement shows a characteristic hysteresis. A kinematic model is proposed which relates nonlinearly the displacement and its rate to the applied voltage. The analysis is developed to account quantitatively for the measured quasistatic hysteresis and decay, and to predict resonant dynamical effects.

P. G. Harper

1981-01-01

10

Hysteresis in dielectric electroactive polymers  

NASA Astrophysics Data System (ADS)

In this paper experimental results indicating the presents of hysteresis in the acrylic tape VHB 4910 produced by 3M are presented. It is shown that there are large stress relaxation times associated with this material making it difficult to separate viscoelastic effects and hysteresis. Additionally, a set of Preisach hysteresis models is presented and it is shown that these models fit the experimental results well. The simplest model having only 5 fitting parameters is suggested as the best model as the parameters can be uniquely determined, this not being the case for the other models.

Lassen, B.; Jaffari, M.; Melvad, C.; Kristjánsdóttir, G. R.; Jones, R.

2009-07-01

11

A neural networks model for hysteresis nonlinearity  

Microsoft Academic Search

This paper presents a new approach for modeling hysteresis nonlinearity in piezo-actuators. Under a mild assumption, a mapping, which can be approximated by multi-layer neural networks (MNN), is defined to describe Preisach model. Then, the neural networks (NN) hysteresis model is extended to describe hysteresis function, which relaxes the requirements on hysteresis to be described by Preisach model. An advantage

Li Chuntao; Tan Yonghong

2004-01-01

12

A polycrystal hysteresis model for ferroelectric ceramics  

Microsoft Academic Search

Most key elements of ferroelectric properties are defined through the hysteresis loops. For a ferroelectric ceramic, its loop is contributed collectively by its constituent grains, each having its own hysteresis loop when the ceramic polycrystal is under a cyclic electric field. In this paper, we propose a polycrystal hysteresis model so that the hysteresis loop of a ceramic can be

Y. Su; G. J. Weng

2006-01-01

13

Mach, methodology, hysteresis and economics  

NASA Astrophysics Data System (ADS)

This methodological note examines the epistemological foundations of hysteresis with particular reference to applications to economic systems. The economy principles of Ernst Mach are advocated and used in this assessment.

Cross, R.

2008-11-01

14

Hysteresis phenomena in hydraulic measurement  

NASA Astrophysics Data System (ADS)

Hysteresis phenomena demonstrate the lag between the generation and the removal of some physical phenomena. This paper studies the hysteresis phenomena of the head-drop in a scaled model pump turbine using experiment test and CFD methods. These lag is induced by complicated flow patterns, which influenced the reliability of rotating machine. Keeping the same measurement procedure is concluded for the hydraulic machine measurement.

Ran, H. J.; Luo, X. W.; Chen, Y. L.; Xu, H. Y.; Farhat, M.

2012-11-01

15

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

16

A digital hysteresis loop experiment  

NASA Astrophysics Data System (ADS)

A toroid with primary and secondary windings is used as a transformer to generate magnetic hysteresis curves. The primary winding is driven by a signal generator, which induces an alternating voltage in the secondary winding. Both input and output voltages are captured using a digital storage oscilloscope and processed to generate and display a hysteresis curve. We show such curves are representative of the material used as the transformer core. Data acquisition and processing steps are presented in a manner suitable for use in an undergraduate laboratory or lecture demonstration.

Francavilla, T. L.; Claassen, J. H.; Willard, M. A.

2013-10-01

17

Hysteresis Losses in Rolling and Sliding Friction  

Microsoft Academic Search

Previous work on the mechanism of rolling friction has shown that it is mainly due to elastic hysteresis losses in the rolling elements. Under conditions of uniform tension or torsion it is generally assumed that the energy dissipated by hysteresis is a constant fraction (the hysteresis loss factor) of the elastic energy introduced during the cycle. This elastic input energy

J. A. Greenwood; H. Minshall; D. Tabor

1961-01-01

18

Recursive identification of hysteresis in smart materials  

Microsoft Academic Search

This paper studies recursive identification of hysteresis in smart materials. A Preisach operator with a piece-wise uniform density function is used to model the hysteresis. Persistent excitation conditions for parameter convergence are discussed in terms of the input to the Preisach operator. Two classes of recursive identification schemes are explored, one based on the hysteresis output, the other based on

Xiaobo Tan; John S. Baras

2004-01-01

19

Hysteresis in East Asian unemployment  

Microsoft Academic Search

High-performing Asian economies are quite distinctive with efficient, flexible and responsive labour markets. Comparing the persistence of unemployment in East Asian economies to that in Western countries is difficult due to the data's short time spans and possible structural breaks. This article employs advanced unit root tests to deal with these problems and fails to reject ‘hysteresis’ in the unemployment

Hsiu-Yun Lee; Jyh-Lin Wu; Chiung-Hsiang Lin

2010-01-01

20

Hysteresis in vibrated granular media  

NASA Astrophysics Data System (ADS)

Some general dynamical properties of models for compaction of granular media based on master equations are analyzed. In particular, a one-dimensional lattice model with short-ranged dynamical constraints is considered. The stationary state is consistent with Edward's theory of powders. The system is submitted to processes in which the tapping strength is monotonically increased and decreased. In such processes the behavior of the model resembles the reversible-irreversible branches which have been recently obaserved in experiments. This behavior is understood in terms of the general dynamical properties of the model, and related to the hysteresis cycles exhibited by structural glasses in thermal cycles. The existence of a "normal" solution, i.e., a solution of the master equation which is monotonically approached by all the other solutions, plays a fundamental role in the understanding of the hysteresis effects.

Prados, A.; Brey, J. J.; Sanchez-Rey, B.

2000-09-01

21

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

22

Analysis of a hysteresis motor with overexcitation  

Microsoft Academic Search

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

T. Kataoka; T. Ishikawa; T. Takahashi

1982-01-01

23

Nonlinearity and hysteresis of resonant strain gauges  

Microsoft Academic Search

The nonlinearity and hysteresis effects of the electrostatically activated voltage-driven resonant microbridges have been studied theoretically and experimentally. It is shown that in order to avoid vibration instability and hysteresis to occur, the choices of the ac and dc driving voltages and of the quality factor of a resonator, with a given geometry and choice of materials, are limited by

Chengqun Gui; Rob Legtenberg; Harrie A. C. Tilmans; Jan H. J. Fluitman; Miko Elwenspoek

1998-01-01

24

Adaptive identification and control of hysteresis in smart materials  

Microsoft Academic Search

Hysteresis hinders the effective use of smart materials in sensors and actuators. This paper addresses recursive identification and adaptive inverse control of hysteresis in smart material actuators, where hysteresis is modeled by a Preisach operator with a piecewise uniform density function. Two classes of identification schemes are proposed and compared, one based on the hysteresis output, the other based on

Xiaobo Tan; John S. Baras

2005-01-01

25

Constricted Hysteresis Loops of Barium Titanate.  

National Technical Information Service (NTIS)

An empirical analysis was made of the change in polarization with time for a constricted hysteresis loop at fixed field strengths. Synthetic constricted loops were obtained by placing two polarized disks in antiparallel and applying a high alternating pot...

G. W. Marks R. D. Redin

1967-01-01

26

Percolation model of relative permeability hysteresis  

NASA Astrophysics Data System (ADS)

A mathematical model of relative permeability hysteresis in drainage and imbibition is constructed on the basis of percolation theory. It is shown that the results are in qualitatively agreement with experimental data.

Kadet, V. V.; Galechyan, A. M.

2013-05-01

27

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

28

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

29

Hysteresis measurement in LabView  

Microsoft Academic Search

This paper deals with the computer-aided automated magnetic scalar hysteresis measurement on ferromagnetic toroidal-shape material. The measurement has been developed in LabView environment using National Instrument Data Acquisition Cards. The measurement technique of symmetric minor loops and first-order reversal curves are presented. It is necessary to measure the magnetic hysteresis curves of ferromagnetic material to describe the material from magnetic

Péter Kis; Miklós Kuczmann; János Füzi; Amália Iványi

2004-01-01

30

Hysteresis of Electronic Transport in Graphene Transistors  

Microsoft Academic Search

Graphene field effect transistors commonly comprise graphene flakes lying on SiO2 surfaces. The gate-voltage dependent conductance shows hysteresis depending on the gate sweeping rate\\/range. It is shown here that the transistors exhibit two different kinds of hysteresis in their electrical characteristics. Charge transfer causes a positive shift in the gate voltage of the minimum conductance, while capacitive gating can cause

Haomin Wang; Yihong Wu; Chunxiao Cong; Jingzhi Shang; Ting Yu

2010-01-01

31

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

32

Statistical mechanical origin of hysteresis in ferroelectrics  

NASA Astrophysics Data System (ADS)

Hysteresis in ferroelectric materials is a strong non-linear phenomenon, the origin of which has drawn considerable attention. Based on the hopping probability function of the lattice-center ion crossing the ferroelectric double-well potential, a statistical mechanical theory is proposed to model ferroelectric hysteresis behavior. The hopping probability function is obtained from the statistical distribution function of ions in energy space, which is derived from the mathematical permutation and combination of the occupy-states of lattice-center ion. The calculated hysteresis agrees well with experimental measurements. In particular, the model provides interesting explanations to the polarization current and the coercive field, which differ from traditional microscopic models and thermodynamic theories.

Yang, Feng; Hu, Guangda; Xu, Baixiang; Wu, Weibing; Yang, Changhong; Wu, Haitao

2012-08-01

33

Conditioning laboratory columns for hysteresis studies  

NASA Astrophysics Data System (ADS)

Evaluating surface area effects on chemical transport properties required estimating the role of hysteresis in the chemical transport processes. To evaluate hysteresis effect unsaturated soil columns at comparable water contents and flow rates were needed. But one column needed to be wetting and a comparable column needed to undergoing drying. Taking advantage of the nearly non-hysteretic behavior in the hydraulic conductivity-water content function, the wetting column was brought to a constant flux rate from a dry condition. The second column was brought to the same flow rate but was started from a wet condition. The apparatus and equilibration times are presented.

Sisson, J. B.; Schaffer, A.

2002-12-01

34

A note on the macroeconomic modelling of unemployment hysteresis  

Microsoft Academic Search

In macroeconomics, unemployment hysteresis typically arises as a special case of an otherwise stationary model. Imposing hysteresis is often equivalent to imposing a random walk, i.e. a situation in which the permanent fraction of a shock is equal to unity. This paper develops a more general linear model of unemployment hysteresis in which permanency is viewed as a continuous, rather

Knut Roed

1999-01-01

35

Robust control for uncertain systems preceded by hysteresis and disturbances  

Microsoft Academic Search

This paper discusses the robust control for the uncertain discrete time linear systems preceded with hysteresis and disturbances. The contribution of the paper is the fusion of the hysteresis model with the adaptive sliding mode control techniques without constructing the inverse hysteresis nonlinearity. The proposed scheme eliminates the traditional over-parameterization by only adapting the parameters (which are generated from the

Xinkai Chen; Takeshi Hisayama

2007-01-01

36

Eliminating the hysteresis effect for reactive sputtering processes  

Microsoft Academic Search

Reactive sputter processes frequently exhibit stability problems. The cause of this is that these processes normally exhibit hysteresis effects in the processing curves. Eliminating the hysteresis would significantly simplify the use of reactive sputtering processes. So far the only known way of eliminating the hysteresis is to increase the pumping speed to unrealistically high values. By an increased understanding of

T. Nyberg; S. Berg; U. Helmersson; K. Hartig

2005-01-01

37

Preisach modeling and compensation for smart material hysteresis  

Microsoft Academic Search

Many of the Smart materials being investigated (e.g., Shape Memory Alloys (SMAs), piezoceramics, and magnetostrictives) exhibit significant hysteresis effects, especially when driven with large control signals. In this paper the similarity between the microscopic domain kinematics that generate static hysteresis effects, or ferromagnetics, piezoceramics and SMAs is noted. The Preisach independent domain hysteresis model, and its derivatives, have been shown

Declan C. Hughes; John T. Wen

1995-01-01

38

EMTP simulation of a STATCOM using hysteresis current control  

Microsoft Academic Search

An alternative control strategy of a STATCOM, based on hysteresis current control of the switches is presented. It is shown that a STATCOM under hysteresis current control will have nearly sinusoidal output current for reactive power compensation while keeping the STATCOM in its simplest configuration. The proposed device was simulated using ATP-EMTP, and the results demonstrate the advantages of hysteresis

D. Sutanto; L. A. Snider; K. L. Mok

1999-01-01

39

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

2012-01-17

40

Perceptual Hysteresis Thresholding: Towards Driver Visibility Descriptors  

Microsoft Academic Search

To develop driving assistance systems which alert the driver in case of inadequate speed according to the visibility conditions, it is necessary to have descriptors of the driver visibility and in particular to detect the visible features in the image grabbed by the camera. In this aim, a hysteresis filter is proposed, which is based on the visibility level (VL)

Nicolas Hautière; Jean-Philippe Tarel; Roland Brémond

2007-01-01

41

MITIGATION OF MAGNET HYSTERESIS EFFECTS AT LANSCE  

Microsoft Academic Search

We have developed a scheme to mitigate the effects of magnet hysteresis in a beamline with a complex arrangement of magnets. The complexity is due to the fact that two power supplies power eight magnets. While some of the magnets are powered by just one of the two supplies, others are excited with the currents from both supplies, with the

R. McCrady; R. Keller

2006-01-01

42

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

43

Shear hysteresis of rock at intermediate strains  

Microsoft Academic Search

Rocks with appropriate microsctructure are nonlinear with hysteresis in the strain range 10-6 to 10-3 while showing little permanent damage during deformation. Nonlinear effects alter strong motions produced by earthquakes and explosions and may lead to new methods for relating the mechanical properties of rock to microstructure and transport properties. Results of laboratory torsion experiments will be presented to demonstrate

Brian P. Bonner; C. Aracne-Ruddle; C. Shew

1995-01-01

44

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

45

Continuous Depinning Transition with an Unusual Hysteresis Effect  

NASA Astrophysics Data System (ADS)

We identify a strange hysteresis which occurs in models of the depinning transition with both elastic and transient overshoot stresses. This hysteresis occurs generically despite the fact that the phase transition is still second order. We calculate the size of the hysteresis gap exactly in a large class of models. Because it is caused by irrelevant perturbations, the hysteresis does not show up in the field theory of the continuum limit. But since it is a real phenomenon it may be a cause for the hysteresis observed in natural depinning. We therefore discuss its experimental and numerical signatures which include microscopic nucleation.

Maimon, Ron; Schwarz, J. M.

2004-06-01

46

Rotational hysteresis of exchange-spring magnets.  

SciTech Connect

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 show that the magnetization rotation created in the magnetically soft Fe layer by a rotating magnetic field is hysteretic. The rotational hysteresis is due to the reversal of the chirality of the spin spiral structure. Micromagnetic simulations reveal two reversal modes of the chirality, one at low fields due to an in-plane untwisting of the spiral, and the other, at high fields, due to an out-of-plane fanning of the spiral.

Jiang, J.S.; Bader, S.D.; Kaper, H.; Leaf, G.K.; Shull, R.D.; Shapiro, A.J.; Gornakov, V.S.; Nikitenko, V.I.; Platt, C.L.; Berkowitz, A.E.; David, S.; Fullerton, E.E.

2002-03-27

47

Energetic model of ferromagnetic hysteresis: Isotropic magnetization  

NASA Astrophysics Data System (ADS)

The model is based on considerations of energy balance and statistical domain behavior. The parameters are related to macroscopic hysteresis features such as coercivity, initial susceptibility, saturation, and remanence and identification strategies are presented for static and dynamic magnetization processes. Furthermore, the model parameters are related to spontaneous magnetization, magnetocrystalline anisotropy, magnetostriction, and microstructure geometry which assist in the interpretation of the hysteresis dependence on stress, temperature, and direction of magnetization. Examples and predictions are the magnetization reversal in low dimensional structures, stress demagnetization, temporary decay of magnetization, Barkhausen noise, and the behavior of materials with multiple phases. Finally, the fictitious statistical domains (or unit magnetization reversals) are related to the magnetic spin moments, which enables a quantum-mechanical interpretation of the model.

Hauser, Hans

2004-09-01

48

Domain theory for capillary condensation hysteresis  

NASA Astrophysics Data System (ADS)

We discuss how the original domain theory for capillary condensation hysteresis [D. H. Everett, The Solid-Gas Interface, Vol. 2 (Marcel Dekker, New York, 1967), pp. 1055-1113] must be modified to account for the presence of the film adsorbed at the pore surface. We show that the original predictions (scanning behavior, congruence) are not valid unless the existence of the adsorbed film is neglected or the dependence of its thickness on the pressure is neglected. We also calculate the scanning curves and subloops that are expected for an assembly of pores having either a regular or irregular (nonconstant) section. These predictions over the scanning behavior within capillary condensation hysteresis can be used to check whether real materials are made up of independent pores or not. Our results are discussed in the light of experiments and density functional theory calculations for adsorption in porous media.

Coasne, Benoit; Gubbins, Keith E.; Pellenq, Roland J.-M.

2005-07-01

49

Contact angle hysteresis due to surface roughness  

Microsoft Academic Search

By means of the calculus of variations it is shown that even on rough surfaces the Young equation applies and that the Wenzel\\u000a equation relies on a false assumption. Contact angle hysteresis, i .e. the difference in the apparent advancing and receding\\u000a angles, for homogeneous rough solid substrates is due to the local slope of the solid surface at the

M. Brackel; F. De Bisschop; P. Joos

50

A novel hysteresis model in unsaturated soil  

Microsoft Academic Search

This study presents a novel hysteresis model based on van Genuchten's soil-moisture relationships. The proposed model yields a series of closed-form relationships in which two shape factors and are determined from the main drying and wetting curves. Experimental and literature-cited data were used to assess model accuracy. The proposed model was also compared with the Scott and KP models. Analytical

Han-Chen Huang; Yih-Chi Tan; Chen-Wuing Liu; Chu-Hui Chen

2005-01-01

51

The hysteresis limit in relaxation oscillation problems  

NASA Astrophysics Data System (ADS)

A singularly perturbed differential equation with a small coefficient multiplying the derivative is shown to exhibit a limiting hysteresis behavior as the singular parameter tends to zero. The convergence takes place in the space of left-continuous regulated functions and is related to the generalized Helly selection principle for regulated functions established by Franková. Examples show that convergence cannot be expected in general if no regularity is assumed either for the forcing term or for the equilibrium set.

Krejcí, P.

2005-01-01

52

Hysteresis-Induced Long-Time Tails  

NASA Astrophysics Data System (ADS)

It is shown analytically that the output of the standard model for complex, nonlocal hysteresis, the Preisach model, exhibits long-time tails under quite general conditions. For uncorrelated input signals the exponent of the algebraic output correlation decay is determined solely by the tails of the input and the Preisach density. Correspondingly we identify universality classes leading to identical algebraic tails. These results predict the occurrence of 1/f noise for a large class of hysteretic systems.

Radons, Günter

2008-06-01

53

Dielectric hysteresis measurement in lossy ferroelectrics  

Microsoft Academic Search

The conventional Sawyer-Tower circuit is modified so as to employ a quasi-DC electric-field rather than the 60Hz AC electric-field. By using this modified Sawyer-Tower method, the P-E hysteresis loop can be determined using 1 cycle of electric field. This technique enables the samples to avoid the joule heating induced breakdown, which often occurred under the cyclic load of the 60

Jae-Hwan Park; Byung-Kook Kim; Jae-Gwan Park; In-Tae Kim; Hae-June Je; Yoonho Klm; Soon Ja Park

1999-01-01

54

Hysteresis effects in stereopsis and binocular rivalry.  

PubMed

Neural hysteresis plays a fundamental role in stereopsis and reveals the existence of positive feedback at the cortical level [Wilson, H. R., & Cowan, J. D. (1973). A mathematical theory of the functional dynamics of cortical and thalamic nervous tissue. Kybernetik 13(2), 55-80]. We measured hysteresis as a function of orientation disparity in tilted gratings in which a transition is perceived between stereopsis and binocular rivalry. The patterns consisted of sinusoidal gratings with orientation disparities (0 degrees, 1 degrees, 2 degrees,..., 40 degrees) resulting in various degrees of tilt. A movie of these 41 pattern pairs was shown at a rate of 0.5, 1 or 2 pattern pairs per second, in forward or reverse order. Two transition points were measured: the point at which the single tilted grating appeared to split into two rivalrous gratings (T1), and the point at which two rivalrous gratings appeared to merge into a single tilted grating (T2). The transitions occurred at different orientation disparities (T1=25.4 degrees, T2=17.0 degrees) which was consistent with hysteresis and far exceeded the difference which could be attributed to reaction time. The results are consistent with a cortical model which includes positive feedback and recurrent inhibition between neural units representing different eyes and orientations. PMID:18234273

Buckthought, Athena; Kim, Jeounghoon; Wilson, Hugh R

2008-01-29

55

Effect of Air gap variation on characteristics of an Axial flux hysteresis motor  

Microsoft Academic Search

Axial flux hysteresis motor (AFHM) such as other types of hysteresis motor is self-starting synchronous motor that use the hysteresis characteristics of magnetic materials. It is known that the magnetic characteristics of hysteresis motor could be easily affected by air gap and structure dimensions variation. Air gap length plays an important role in flux distribution in hysteresis ring that can

Mohammad Modarres; Abolfazl Vahedi; Mohammadreza Ghazanchaei

2010-01-01

56

Thermal hysteresis of interface biased dipolar coupled nanoelements  

NASA Astrophysics Data System (ADS)

We report a theoretical investigation of thermal hysteresis of a pair of interface biased elliptical iron nanoelements, separated by an ultrathin layer of nonmagnetic material. The thermal hysteresis originates in the strong dipolar interaction, and is tunable by the nature of the low temperature state and the eccentricity of the nanoelements. The width of the thermal hysteresis varies from 500 K to 100 K for lateral dimensions of 125 nm × 65 nm and 145 nm × 65 nm.

Dantas, Ana L.; Queiroz, Idalmir; Reboucas, Gustavo; Dias, Maria G.; Carriço, A. S.

2013-05-01

57

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

58

Optical hysteresis in liquid crystals with helicoidal distributed feedback  

NASA Astrophysics Data System (ADS)

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.

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

1985-11-01

59

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

2007-07-12

60

Feedback compensation of shape memory alloy hysteresis  

NASA Astrophysics Data System (ADS)

Traditionally, actuators have been large and heavy (eg., motors). Because of their physical size and structure, they increase the size and weight of the entire system. In many applications, it is desirable to find an alternative to these conventional type of actuators. Shape memory alloy (SMA) has been considered as an actuator for applications that require large force and displacement. SMA are small and light weight which greatly reduces the overall size of a system. However, two factors have hampered the usefulness of such actuators, hysteresis and bandwidth limitation. This thesis examines the hysteresis phenomenon from a control point of view. Particular focus is placed on SMA wires attached to a flexible structure. Generally speaking, there are two ways to compensate for hysteresis, open loop compensation and closed loop feedback compensation. The open loop compensation requires an accurate model; this thesis uses a closed loop approach which considers the feedback of the SMA wire force or length. Very little previous work exists in the literature in this area since most researchers consider SMA to be essentially a static device. However even at low bandwidths, SMA cannot be considered a static device due in part to its intrinsic hysteretic properties. By using a simple lumped temperature model, it is shown that proportional feedback with a suitable range of gains would render the closed loop system stable. This is verified experimentally in a simple experimental setup consisting of a flexible aluminum beam and to a Nitinol shape memory alloy wire that applies it bending force to the end of the beam.

Dickinson, Carrie A.

61

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

62

On the origin of contact angle hysteresis  

NASA Astrophysics Data System (ADS)

In this study, we consider a simple distribution of defects on a substrate, or a sinusoidal surface, and show explicitly how the pinning and depinning occur for a two dimensional liquid drop on such non-ideal surfaces as the volume of the drop is increased or decreased. We show that the contact angle hysteresis (CAH) emerges from this simple model even though we do not take any effect of viscous dissipation into account, which is in contrast with the conventional theory where the CAH originates from the viscous dissipation inside the liquid around the contact line just after depinning.

Yoshitaki, Yumiko; Okumura, Ko

2009-11-01

63

Applications of a theory of ferromagnetic hysteresis  

SciTech Connect

The differential equation dB/dt = ..cap alpha.. absolute value of dH/dt (f(H) - B) + dH/dt g(H) and a set of restrictions on the material functions f and g yield a theory of rate independent hysteresis for isoperm ferromagnetic materials. A modification based on exchanging the positions of B and H in the differential equation and on allowing for the dependence of the material functions on dH/dt extends the theory to rate dependent, nonisoperm materials. The theory and its extension exhibit all of the important features of ferromagnetic hysteresis, including the existence and stability of minor loops. Both are well suited for use in numerical field solving codes. Examples in which the material functions are simple combinations of analytic functions are presented here for Mn-Zn ferrite, Permalloy, CMD5005, and CoCr thin film. Also presented is a procedure for constructing a two dimensional vector model that yields bell-shaped and M-shaped curves for graphs of the angular variation of the coercive field.

Hodgdon, M.L.

1987-01-01

64

An inclusive model of ferromagnetic hysteresis  

NASA Astrophysics Data System (ADS)

A new inclusive macroscopic model of ferromagnetic hysteresis is proposed. The model is developed from a Stoner-Wohlfarth approach by adding mean field or nearest neighbour dipole-dipole interactions. Pinning of domain rotation is also postulated, and a rotational pinning extension included. The model includes the principal features of the Jiles-Atherton model in the previous Atherton-Beattie extension of the Stoner-Wohlfarth model, but still omits the domain wall energy effects included in the Globus model. The new model describes both reversible and irreversible processes, and hysteresis caused by combinations of interaction, anisotropy, and pinning. Computational approaches to both two and three dimensional calculations are detailed, and examples given. Simulations of hard magnetic materials are done, including major loops to near saturation, minor loops, and demagnetizations. The complete 2 x 2 magnetization tensor response is shown, including fan diagram representations. The minor loop simulations involve complicated sets of field turning points typical of the Preisach model, and the minor loops are seen to exhibit incongruence and eventual closure. The demagnetization simulations are done for both rotating and oscillating applied field cycles. Both isotropic and anisotropic polycrystalline easy axis distributions are treated.

Phelps, Brian Fletcher

65

Percolation and hysteresis in macroscopic capillarity  

NASA Astrophysics Data System (ADS)

The concepts of relative permeability and capillary pressure are crucial for the accepted traditional theory of two phase flow in porous media. Recently a theoretical approach was introduced that does not require these concepts as input [1][2][3]. Instead it was based on the concept of hydraulic percolation of fluid phases. The presentation will describe this novel approach. It allows to simulate processes with simultaneous occurence of drainage and imbibition. Furthermore, it predicts residual saturations and their spatiotemporal changes during two phase immiscible displacement [1][2][3][4][5]. [1] R. Hilfer. Capillary Pressure, Hysteresis and Residual Saturation in Porous Media, Physica A, vol. 359, pp. 119, 2006. [2] R. Hilfer. Macroscopic Capillarity and Hysteresis for Flow in Porous Media, Physical Review E, vol. 73, pp. 016307, 2006. [3] R. Hilfer. Macroscopic capillarity without a constitutive capillary pressure function, Physica A, vol. 371, pp. 209, 2006. [4] R. Hilfer. Modeling and Simulation of Macrocapillarity, in: P. Garrido et al. (eds.) Modeling and Simulation of Materials vol. CP1091, pp. 141, American Institute of Physcis, New York, 2009. [5] R. Hilfer and F. Doster. Percolation as a basic concept for macroscopic capillarity, Transport in Porous Media, DOI 10.1007/s11242-009-9395-0, in print, 2009.

Hilfer, Rudolf

2010-05-01

66

Hysteresis and the Dynamic Elasticity of Consolidated Granular Materials  

Microsoft Academic Search

Quasistatic elasticity measurements on rocks show them to be strikingly nonlinear and to have elastic hysteresis with end point memory. When the model for this quasistatic elasticity is extended to the description of nonlinear dynamic elasticity the elastic elements responsible for the hysteresis dominate the behavior. Consequently, in a resonant bar, driven to nonlinearity, the frequency shift and the attenuation

R. A. Guyer; James Tencate; Paul Johnson

1999-01-01

67

Hysteresis modeling of synchronous reluctance motor considering PWM input voltage  

Microsoft Academic Search

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

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

2000-01-01

68

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

69

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

70

Hysteresis effects in the two-mode dye ring laser  

Microsoft Academic Search

By inserting an optical diode consisting of Faraday and quartz rotators into the cavity of a dye ring laser and by applying a sinusoidal current at 10 Hz to the Faraday rotator, we have been able to observe hysteresis in the intensity of each counterpropagating laser mode. The hysteresis results from the laser's attempts to switch among metastable states in

Edward C. Gage; Leonard Mandel

1989-01-01

71

Formulation of capillary hysteresis with internal state variables  

Microsoft Academic Search

A thermodynamically consistent framework is proposed for modeling the hysteresis of capillarity in partially saturated porous media. Capillary hysteresis is viewed as an intrinsic dissipation mechanism, which can be characterized by a set of internal state variables. The volume fractions of pore fluids are assumed to be additively decomposed into a reversible part and an irreversible part. The irreversible part

Changfu Wei; Mandar M. Dewoolkar

2006-01-01

72

Influence of frequency noise on nascent hysteresis in optical bistability  

SciTech Connect

The authors study the influence of frequency noise on optical bistability in the neighborhood of the critical point where the hysteresis loop appears. They show that when the transmitted field evolves on a faster time scale than that of the noise, the hysteresis loop shifts toward lower values of the incident pumping field.

Lefever, R.; Turner, J.W.; Lugiato, L.A.

1987-09-01

73

Abrupt transitions and hysteresis in thermohaline laboratory models  

Microsoft Academic Search

Steady ocean circulation models can change in three different ways as the forcing parameters are slowly altered: smooth evolution, abrupt transition without hysteresis, and abrupt transition with hysteresis. In the second, the transition point is independent upon whether the driving parameter is increased or decreased. In the third, the transition points differ depending upon whether the driving parameter approachs from

Jack Whitehead

2008-01-01

74

Influence of frequency noise on nascent hysteresis in optical bistability  

Microsoft Academic Search

We study the influence of frequency noise on optical bistability in the neighborhood of the critical point where the hysteresis loop appears. We show that when the transmitted field evolves on a faster time scale than that of the noise, the hysteresis loop shifts toward lower values of the incident pumping field.

R. Lefever; J. Wm. Turner; L. A. Lugiato

1987-01-01

75

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

76

Analysis of Noise Spectral Density for Phenomenological Models of Hysteresis  

Microsoft Academic Search

A statistical technique based on Monte Carlo simulations is developed to compute the spectral densities of the output variable in phenomenological models of hysteresis. The input signal is described by an Ornstein-Uhlenbeck process and the magnetization is computed by using various hysteresis models: the Energetic, Jiles-Atherton, and Preisach models. General qualitative features of these spectral densities are examined and their

Ayodeji Adedoyin; Mihai Dimian; Petru Andrei

2009-01-01

77

Interpreting diel hysteresis between soil respiration and temperature  

Microsoft Academic Search

Increasing use of high-frequency automated soil respiration measurement techniques has revealed complex diel relationships between soil respiration and temperature. Soil surface flux is often lagged from soil temperature by several hours, which results in semi-elliptical hysteresis loops when surface flux is plotted as a function of soil temperature. Both biological and physical explanations have been suggested for hysteresis patterns, and

N. R. Nickerson; C. L. Phillips; D. A. Risk; B. J. Bond

2009-01-01

78

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

79

The Principle Mechanical and Electrical Features of a Hysteresis Clutch  

Microsoft Academic Search

The hysteresis loss that occurs in magnetic devices subjected to changing magnetic fields usually represents a detrimental condition. One exception, however, is the hysteresis clutch where this loss is utilized to perform a useful function. One particular type1 clutch is described and its chief mechanical and electrical features are summarized. Its utility as a variable speed drive is also illustrated.

Lowell B. Brown

1956-01-01

80

Compensation of Scanner Creep and Hysteresis for AFM Nanomanipulation  

Microsoft Academic Search

Nanomanipulation with atomic force microscopes (AFMs) for nanoparticles with overall sizes on the order of 10 nm has been hampered in the past by the large spatial uncertainties encountered in tip positioning. This paper addresses the compensation of nonlinear effects of creep and hysteresis on the piezo scanners which drive most AFMs. Creep and hysteresis are modeled as the superposition

Babak Mokaberi; Aristides A. G. Requicha

2008-01-01

81

Semi-empirical modeling of hysteresis compensation in magnetostrictive actuator  

NASA Astrophysics Data System (ADS)

Hysteresis causes a delayed response to a given input in a magnetostrictive actuator (MA). It becomes critical when the MA has to be controlled in precise and real-time mode. An efficient way to compensate hysteresis must be considered. The Jiles-Atherton and Preisach models have been applied mostly in the literature, but these models need complex mathematics that makes them difficult to be applied in precise and real-time mode. Thus, this paper presents a semi-empirical model to compensate hysteresis in the MA. The idea comes from the similarity of the shapes between the hysteresis-compensated input voltage to the MA, and the output voltage of R-C circuit. The respective hysteresis-compensated input voltage and R-C circuit are expressed as polynomial and exponential equations, resulting in two closed-form equations about capacitance. One set of capacitance values for each frequency is selected by simulating the derived equations. Experiments are performed to choose one capacitance value among a set of capacitance values from simulation, based on trial-and-error. The concept of the hysteresis loss is introduced and defined as the ratio of areas between the hysteretic and reference curves. It is observed that the percent change of hysteresis loss increases as the frequency increases up to 400 Hz, but decreases with further increase of the frequency up to 800 Hz. It can be concluded that the proposed approach is effective to compensate hysteresis in the MA, and that hysteresis loss definition introduced by us can be used as a helpful measure of hysteresis compensation.

Ji, Ki-Hyun; Park, Hae-Jung; Park, Young-Woo; Wereley, Norman M.

2013-04-01

82

Wave Tunneling and Hysteresis in Nonlinear Junctions  

SciTech Connect

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 Schroedinger system that contains a nonlinear junction.

Wan Wenjie; Muenzel, Stefan; Fleischer, Jason W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544 (United States)

2010-02-19

83

Wave Tunneling and Hysteresis in Nonlinear Junctions  

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

84

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

2010-02-18

85

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

86

A physical model for the electrical hysteresis of thin-film ferroelectric capacitors  

Microsoft Academic Search

A mathematical model for the electrical hysteresis of ferroelectric thin-film capacitors based on the Landau free energy theory is presented. The hysteresis of a single ferroelectric crystallite is derived from free energy considerations. The hysteresis of a polycrystalline material is obtained by accounting for the spatial distribution and the structural phase of the crystallites. The hysteresis functions for the tetragonal

Ciaran J. Brennan

1992-01-01

87

Fatigue, Hysteresis and Acoustic Emission. Parts 1 and 2.  

National Technical Information Service (NTIS)

The basic objective of this research program is to characterize the development of material fatigue by means of stress-strain hysteresis and acoustic emission measurements. We have conjectured that the accumulation and organization of damage in material f...

S. A. Guralnick T. Erber

1992-01-01

88

Hysteresis in gadolinium oxide metal-oxide-semiconductor capacitors  

NASA Astrophysics Data System (ADS)

This investigation explores how oxidation affects the gadolinium oxide capacitor and the corresponding Gd2O3 hysteresis phenomenon. The current-voltage varied with Gd2O3 thickness and a charged capacitance voltage (C-V) curve with a left shift is also observed in experimental results. The breakdown voltages rise with increasing oxidation time, while the corresponding C-V hysteresis gaps decrease with increasing oxidation time.

Hsieh, Li-Zen; Ko, Hong-Hsi; Kuei, Ping-Yu; Chang, Liann-Be; Jeng, Ming-Jer

2005-10-01

89

Surface figure changes due to thermal cycling hysteresis.  

PubMed

How does thermal cycling hysteresis affect surface figure in low expansivity mirror substrates? Zerodur, ULE, and Cer-Vit 20.3-cm (8-in.) diam mirrors and dilatometer samples were thermally cycled at 6 and 60 K/h with uniform and nonuniform heating. Figure distortions as large as lambda/10 were observed only with nonuniform heating of standard Zerodur, which was the only material exhibiting thermal hysteresis. A new experimental Zerodur appears to be free of this problem. PMID:20523381

Jacobs, S F; Johnston, S C; Sasian, J M; Watson, M; Targove, J D; Bass, D

1987-10-15

90

Origin of hysteresis in a proximity josephson junction.  

PubMed

We investigate hysteresis in the transport properties of superconductor-normal-metal-superconductor (S-N-S) junctions at low temperatures by measuring directly the electron temperature in the normal metal. Our results demonstrate unambiguously that the hysteresis results from an increase of the normal-metal electron temperature once the junction switches to the resistive state. In our geometry, the electron temperature increase is governed by the thermal resistance of the superconducting electrodes of the junction. PMID:18764493

Courtois, H; Meschke, M; Peltonen, J T; Pekola, J P

2008-08-08

91

Magnetomechanical hysteresis damping in FeAl alloys  

Microsoft Academic Search

The magnetomechanical hysteresis damping of Fe-Al alloys has been investigated using a computer-controlled automatic inverted torsion pendulum. It has been shown that Al content and heat treatment have a significant effect on the magnetomechanical hysteresis damping of the alloys. The Fe-10.5 (at.%)Al alloy has an optimal damping capacity after it was air-cooled from 900°C and the Fe-Al alloys with 29(at.)%Al

Z. C. Zhou; Z. C. Shen; Z. Jiang; F. S. Han

2005-01-01

92

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

93

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

94

Stiffness and hysteresis properties of some prosthetic feet.  

PubMed

A prosthetic foot is an important element of a prosthesis, although it is not always fully recognized that the properties of the foot, along with the prosthetic knee joint and the socket, are in part responsible for the stability and metabolic energy cost during walking. The stiffness and the hysteresis, which are the topics of this paper, are not properly prescribed, but could be adapted to improve the prosthetic walking performance. The shape is strongly related to the cosmetic appearance and so can not be altered to effect these improvements. Because detailed comparable data on foot stiffness and hysteresis, which are necessary to quantify the differences between different types of feet, are absent in literature, these properties were measured by the authors in a laboratory setup for nine different prosthetic feet, bare and with two different shoes. One test cycle consisted of measurements of load deformation curves in 66 positions, representing the range from heel strike to toe-off. The hysteresis is defined by the energy loss as a part of the total deformation energy. Without shoes significant differences in hysteresis between the feet exist, while with sport shoes the differences in hysteresis between the feet vanish for the most part. Applying a leather shoe leads to an increase of hysteresis loss for all tested feet. The stiffness turned out to be non-constant, so mean stiffness is used.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2095529

van Jaarsveld, H W; Grootenboer, H J; de Vries, J; Koopman, H F

1990-12-01

95

Triangular Current: Method for Measuring Hysteresis Loops of Ferroelectric Capacitors  

NASA Astrophysics Data System (ADS)

In this paper, we present a triangular current (TC) method for measuring the hysteresis loops of Pb(Zr,Ti)O3 capacitors prepared on Pt/Ta/SiO2/Si substrates. Like the constant current (CC) method, this method is a current source mode method for obtaining hysteresis loops. By applying a triangular charging current to a specimen, a measured voltage profile, which is almost noiseless and smooth in the high-field region, is obtained and its hysteresis curve can be determined using integral calculus to convert the charging current to charge. Under various charging conditions, the similarity of the obtained hysteresis curves implies that the step charging current and number of steps do not affect the measured results. Moreover, the parasitic effect of the probe setup is found to possibly increase the maximum polarization of the ferroelectric capacitor as the area of the capacitor is reduced. The TC method can be utilized to determine the parasitic capacitance of the probe setup and then can easily determine the corrected hysteresis loops of small capacitors. These findings reveal that the TC method constitutes a new method for measuring the hysteresis loops of ferroelectric capacitors.

Wang, Ding-Yeong; Chang, Chun-Yen

2004-09-01

96

Titration and hysteresis in epigenetic chromatin silencing  

NASA Astrophysics Data System (ADS)

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.

Dayarian, Adel; Sengupta, Anirvan M.

2013-06-01

97

HYSTERESIS OF BACKFLOW IMPRINTED IN COLLIMATED JETS  

SciTech Connect

We report two different types of backflow from jets by performing two-dimensional special relativistic hydrodynamical simulations. One is anti-parallel and quasi-straight to the main jet (quasi-straight backflow), and the other is a bent path of the backflow (bent backflow). We find that the former appears when the head advance speed is comparable to or higher than the local sound speed at the hotspot, while the latter appears when the head advance speed is slower than the sound speed at the hotspot. Bent backflow collides with the unshocked jet and laterally squeezes the jet. At the same time, a pair of new oblique shocks is formed at the tip of the jet and new bent fast backflows are generated via these oblique shocks. The hysteresis of backflow collisions is thus imprinted in the jet as a node and anti-node structure. This process also promotes broadening of the jet cross-sectional area and also causes a decrease in the head advance velocity. This hydrodynamic process may be tested by observations of compact young jets.

Mizuta, Akira [Center for Frontier Science, Chiba University Yayoi-cho 1-33, Inage-ku, Chiba 263-8522 (Japan); Kino, Motoki [National Astronomical Observatory of Japan, Mitaka 181-8588 (Japan); Nagakura, Hiroki [Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

2010-01-20

98

Experiments on sorption hysteresis of desiccant materials  

SciTech Connect

Solid desiccant cooling systems take advantage of solar energy for air conditioning. The process involves passing air through a desiccant bed for drying and subsequent evaporative cooling to provide the air conditioning. The desiccant is then regenerated with hot air provided by a gas burner or solar collectors. This performance is limited by the capacity of the desiccant, its sorption properties, and the long-term stability of the desiccant material under cyclic operation conditions. Therefore, we have developed a versatile test facility to measure the sorption properties of candidate solid desiccant materials under dynamic conditions, under different geometrical configurations, and under a broad range of process air stream conditions, characteristic of desiccant dehumidifer operation. We identified a dependence of the sorption processes on air velocity and the test cell aspect ratio and the dynamic hysteresis between adsorption and desorption processes. These experiments were geared to provide data on the dynamic performance of silica gel in a parallel-passage configuration to prepare for tests with a rotary dehumidifier that will be conducted at SERI in late FY 1984. We also recommend improving the accuracy of the isotopic perturbation technique.

Pesaran, A.; Zangrando, F.

1984-08-01

99

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

100

Chromophore packing leads to hysteresis in GFP  

PubMed Central

Green fluorescent protein (GFP) possesses a unique folding landscape with a dual basin, leading to the hysteretic folding behavior observed in experiment. While theoretical data do not have the resolution necessary to observe details of the chromophore during refolding, experimental results point to the chromophore as the cause of the observed hysteresis. Using NMR spectroscopy, which probes at the level of the individual residue, the hysteretic intermediate state is further characterized in the context of the loosely-folded native-like state {Niso} predicted in simulation. In the present study, several residues located in the lid of GFP indicate heterogeneity of the native states. Some of these residues show chemical shifts when the native-like intermediate {Niso} responsible for GFP's hysteretic folding behavior is trapped. Observed changes in the chromophore are consistent with increased flexibility or isomerization in {Niso} as predicted in recent theoretical work. Here we observe multiple chromophore environments within the native state are averaged in the trapped intermediate, linking chromophore flexibility to mispacking in the trapped intermediate. The present work is experimental evidence for the proposed final “locking” mechanism in GFP folding forming an incorrectly or loosely packed barrel under intermediate (hysteretic) folding conditions.

Andrews, Benjamin T.; Roy, Melinda; Jennings, Patricia A.

2010-01-01

101

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

102

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

103

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

104

Contact Hysteresis and Friction of Alkanethiol SAMs on Au  

SciTech Connect

Nanoindentation has been combhed with nanometer-scale friction measurements to identi~ dissipative mechanisms responsible for friction in hexadecanethiol self-assembled monolayer on Au. We have demonstrated that friction is primarily due to viscoelastic relaxations within the films, which give rise to contact hysteresis when deformation rates are within the ranges of 5 and 200 k. We observe that this contact hysteresis increases with exposure to air such that the friction coefficient increases from 0.004 to 0.075 when films are exposed to air for 40 days. Both hysteresis and friction increase with probe speed, and we present a model of friction that characterizes this speed dependence and which also predicts a linear dependence of friction on normal force in thin organic films. Finally, we identify several short-term wear regimes and identify that wear changes dramatically when fdms age.

Houston, J.E.; Kiely, J.D.

1998-10-14

105

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

2013-06-03

106

Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

107

Inverted hysteresis loops in CoO-based multilayers  

NASA Astrophysics Data System (ADS)

We have observed inverted hysteresis loops in a number of multilayer [Co-O]/Cu and [Co-O]/Al multilayers. In this phenomenon, the forward and reverse branches of a hysteresis loop are shifted along the magnetic field axis in such a way that they cross each other and we report the dependence of this phenomenon on magnetic layer thickness. In many cases the Cu or Al layer is thick enough that interlayer interactions between magnetic layers are not possible. It is suggested that interface exchange between Co and Co-O phases within the magnetic layer is important in these multilayers and that this phenomenon is closely related to shifted hysteresis loops which are also produced by interface exchange. We do not find this behavior in nominally homogeneous Co-O films indicating that the multilayer nature of the material is important. A two-phase model is presented which is able to qualitatively explain some of the observed results.

Gao, C.; O'Shea, M. J.

1993-10-01

108

Hysteresis effects in the two-mode dye ring laser  

SciTech Connect

By inserting an optical diode consisting of Faraday and quartz rotators into the cavity of a dye ring laser and by applying a sinusoidal current at 10 Hz to the Faraday rotator, we have been able to observe hysteresis in the intensity of each counterpropagating laser mode. The hysteresis results from the laser's attempts to switch among metastable states in response to the external stimulus. We have studied the hysteresis as a function of laser pump parameter a and find that it starts when a exceeds about 25, reaches a peak when a is about 60, and becomes small when a exceeds about 70. At this stage the laser is unable to respond because of the high potential barrier between metastable states. The results are in general agreement with computer solutions of the equations of motion and are related to recent work on stochastic resonance in a dye ring laser.

Gage, E.C.; Mandel, L.

1989-03-01

109

Hysteresis in superconducting short weak links and ? -SQUIDs  

NASA Astrophysics Data System (ADS)

Thermal hysteresis in a micron-size superconducting quantum interference device ( ? -SQUID), with weak links as Josephson junctions, is an obstacle for improving its performance for magnetometry. Following the “hot-spot” model of Skocpol [J. Appl. Phys. 45, 4054 (1974)]10.1063/1.1663912 and by incorporating the temperature dependence of the superconductor thermal conductivity under a linear approximation, we find a much better agreement with the observed temperature dependence of the retrapping current in short superconducting Nb-based weak links and ? -SQUIDs. In addition, using the temperature dependence of the critical current, we find that above a certain temperature hysteresis disappears. We analyze the current-voltage characteristics and the weak link temperature variation in both the hysteretic and nonhysteretic regimes. We also discuss the effect of the weak link geometry in order to widen the temperature range of hysteresis-free operation.

Hazra, Dibyendu; Pascal, Lætitia M. A.; Courtois, Hervé; Gupta, Anjan K.

2010-11-01

110

Role of Surface Roughness in Hysteresis during Adhesive Elastic Contact  

PubMed Central

In experiments that involve contact with adhesion between two surfaces, as found in atomic force microscopy or nanoindentation, two distinct contact force (P) vs. indentation-depth (h) curves are often measured depending on whether the indenter moves towards or away from the sample. The origin of this hysteresis is not well understood and is often attributed to moisture, plasticity or viscoelasticity. Here we report experiments that show that hysteresis can exist in the absence of these effects, and that its magnitude depends on surface roughness. We develop a theoretical model in which the hysteresis appears as the result of a series of surface instabilities, in which the contact area grows or recedes by a finite amount. The model can be used to estimate material properties from contact experiments even when the measured P-h curves are not unique.

Kesari, Haneesh; Doll, Joseph C.; Pruitt, Beth L.; Cai, Wei; Lew, Adrian J.

2010-01-01

111

A modified Prandtl-Ishlinskii modeling method for hysteresis  

NASA Astrophysics Data System (ADS)

A modified Prandtl-Ishlinskii modeling method for rate-independent hysteresis in piezoelectric actuators is proposed in this paper. In this method, a generalized backlash operator (GBO) regarded as the elementary operator is introduced into the model so as to be more flexible for modeling of complex hysteresis. Moreover, the Levenberg-Marquardt algorithm is used to estimate the parameters of the model. Thus, all the parameters of the modified PI model can be determined automatically. From this way, it avoids the tedious procedure for the selection of the operator parameters by trial and error. Then, a group of proper Clarke subgradients of the GBO outputs with respect to their parameters at a non-smooth point is obtained based on the bundle method. Finally, the experimental results of applying the proposed method to the modeling of hysteresis in a piezoelectric actuator and an ultrasonic motor (USM) are illustrated, respectively.

Dong, Ruili; Tan, Yonghong

2009-05-01

112

Hysteresis in transverse galloping: The role of the inflection points  

NASA Astrophysics Data System (ADS)

Transverse galloping is here considered as a one-degree-of-freedom oscillator subjected to aerodynamic forces, which are described by using the quasi-steady hypothesis. The hysteresis of transverse galloping is also analyzed. Approximate solutions of the model are obtained by assuming that the aerodynamic and damping forces are much smaller than the inertial and stiffness ones. The analysis of the approximate solution, which is obtained by means of the method of Krylov-Bogoliubov, reveals the existing link between the hysteresis phenomenon and the number of inflection points at the aerodynamic force coefficient curve, Cy(?); Cy and ? being, respectively, the force coefficient normal to the incident flow and the angle of attack. The influence of the position of these inflection points on the range of flow velocities in which hysteresis takes place is also analyzed.

Barrero-Gil, A.; Sanz-Andrés, A.; Alonso, G.

2009-08-01

113

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

114

Low hysteresis FeMn-based top spin valve.  

PubMed

FeMn-based top spin valves Ta/[FeNi/CoFe]/Cu/CoFe/FeMn/Ta with different Cu and FeMn layers thicknesses were prepared by DC magnetron sputtering at room temperature. It was shown that low field hysteresis due to free layer magnetization reversal can be reduced down to (0.1 divided by 0.2) Oe keeping the GMR ratio higher 8% by using both layers thicknesses optimization and non-collinear geometry of magnetoresistance measurements. Dependence of low field hysteresis and GMR ratio on the angle between applied magnetic field and pinning direction are presented. PMID:23035516

Ustinov, V V; Krinitsina, T P; Milyaev, M A; Naumova, L I; Proglyado, V V

2012-09-01

115

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

116

Control of Hysteresis in Smart Actuators. Part 2. A Robust Control Framework.  

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. But due to the open loop nature of inverse compensation, its performance is susceptible to model uncertai...

X. Tan J. S. Baras

2002-01-01

117

A novel hysteresis bandwidth (NHB) calculation to fix the switching frequency employed in active power filter  

Microsoft Academic Search

Variable switching process is the main issue in practical implementation of fixed band hysteresis current controller in active power filters (APF) that increases the switching frequency and switching losses in power systems. Preventing this case, the Adaptive Hysteresis Current Control (AHCC) has been introduced and developed by many researchers. By this way, The Hysteresis Band (HB) will change adaptively by

Hani Vahedi; Abdolreza Sheikholeslami; Mohammad Tavakoli Bina

2011-01-01

118

THE ROLE OF THE THERMAL HYSTERESIS FACTOR IN TENEBRIO MOLITOR LARVAE  

Microsoft Academic Search

SUMMARY The haemolymph of larvae of Tenebrio molitor contains a factor which produces a thermal hysteresis (a difference between the freezing and melting points) of approximately 0-75 °C. When larvae were acclimated to low temperatures or short photoperiod the thermal hysteresis increased more than twofold. Coincident with the increase in thermal hysteresis the supercooling points and lower lethal temperatures of

JEAN L. PATTERSON; JOHN G. DUMAN

119

Modeling and control with hysteresis and creep of ionic polymer-metal composite (IPMC) actuators  

Microsoft Academic Search

Hysteresis and creep hinder the effective use of IPMC in sensors and actuators. This paper proposes a hybrid model that can precisely portray hysteresis and creep in piezoelectric actuators, which is constructed by a Preisach operator with a piecewise uniform density function and creep operator. Then, the corresponding inverse models for both hysteresis and creep are developed. It studies online

Zhen Chen; Lina Hao; Dingyu Xue; Xinhe Xu; Yanmei Liu

2008-01-01

120

Hysteresis windows for the NbN thin film fabrication process  

Microsoft Academic Search

Since the superconducting transition temperature of a NbN thin film is a function of a hysteresis cycle it is important to know the conditions under which such a hysteresis cycle exists. Agarwal and Shenoy (1981) have determined conditions in the vicinity of the spinodal curve for the existence of a hysteresis window. Using the work of Agarwal and Shenoy and

B. Friedman

1992-01-01

121

Partial and full inverse compensation for hysteresis in smart material systems  

Microsoft Academic Search

Smart material transducers employing piezoceramic or magnetostrictive drive components typically exhibit constitutive nonlinearities and hysteresis at moderate to high drive levels. In this paper, we discuss two techniques to compensate for hysteresis in high performance transducers. The first is based on a complete transducer model, and the resulting compensator accommodates both the constitutive nonlinearities and hysteresis inherent to the smart

Ralph C. Smith; C. Bouron; Rick Zrostlik

2000-01-01

122

Monitoring Recovery and Recrystallization in Interstitial Free (IF) Steel by Magnetic Hysteresis Loop Measurements  

Microsoft Academic Search

In this paper, how structure-sensitive parameters derived from the hysteresis loop, like coercive field, remanent induction, and hysteresis losses, can be used to characterise recovery and recrystallization in cold rolled Ti-Nb stabilised interstitial free ultra low carbon steel is shown. The effect on hysteresis measurements of isothermal annealing treatments applied to industrially cold rolled samples at different temperatures is related

Ane MARTÍNEZ-DE-GUERENU; Fernando ARIZTI; San Sebastián; Kizkitza GURRUCHAGA

2006-01-01

123

Simulation of Relative Permeability Hysteresis to the Nonwetting Phase  

Microsoft Academic Search

In reservoir fluid flow, the situation described by an increase in nonwetting phase saturation followed by an increase in wetting phase saturation causes a relative permeability hysteresis effect that is well known. This paper presents a method which allows the calculation of imbibition relative permeability starting at any saturation. The data required are the drainage curve, the historical maximum non

Francis Carlson

1981-01-01

124

The mechanism by which fish antifreeze proteins cause thermal hysteresis  

Microsoft Academic Search

Antifreeze proteins are characterised by their ability to prevent ice from growing upon cooling below the bulk melting point. This displacement of the freezing temperature of ice is limited and at a sufficiently low temperature a rapid ice growth takes place. The separation of the melting and freezing temperature is usually referred to as thermal hysteresis, and the temperature of

Erlend Kristiansen; Karl Erik Zachariassen

2005-01-01

125

Hysteresis effect in reactive sputtering: a problem of system stability  

Microsoft Academic Search

The hysteresis effect occurring in reactive sputtering is shown by pumping speed analysis to arise from loss in gettering throughput, consequent on reduction in target yield, without consequent rise in pumping throughput. Change in this balance due to higher pumping speed can result in stable conditions.

S. Kadlec; J. Musil; H. Vyskocil

1986-01-01

126

Dynamic and static hysteresis in crayfish stretch receptors  

Microsoft Academic Search

This report calls attention to the magnitude and pervasiveness of hysteresis in the coding from length to afferent discharges in crayfish stretch receptor organs (SRO's). The influence of previous lengths on the rate that corresponded to a particular length L was manifest by a substantial excess of that encountered when L was arrived at from a shorter value over that

J. P. Segundo; O. Diez Martínez

1985-01-01

127

Thermal hysteresis of some important physical properties of nanoparticles  

Microsoft Academic Search

Gold nanoparticles show thermal hysteresis with properties such as surface plasmon absorption, conductivity, and zeta potential. The direction of the incremental change in plasmon peak position and its extinction depend on the nature of surface conjugation. The thermal profile of a surface plasmon resonance spectrum for nanoparticles may serve as a signature for the associated small molecule or macromolecule on

Tapan Sarkar; Shibsekhar Roy; Jaydeep Bhattacharya; Dhananjay Bhattacharya; Chanchal K. Mitra; Anjan Kr. Dasgupta

2008-01-01

128

Static and Dynamic Hysteresis Models for Studying Transformer Transients  

Microsoft Academic Search

Shortcomings of the classical approach in describing magnetization processes in grain-oriented transformer steel is analyzed. A noniterative method of accounting for hysteresis and dynamic properties of transformer core is proposed. Fitting the model to catalog data is described. The method is illustrated by calculating inrush current produced by subsequent transformer energizations.

Sergey E. Zirka; Yuriy I. Moroz; Anthony J. Moses; Cesare Mario Arturi

2011-01-01

129

Instantaneous Feedback Controlled PWM Inverter with Adaptive Hysteresis  

Microsoft Academic Search

A new control strategy for a PWM inverter controlled through adaptive hysteresis in an instantaneous feedback loop is theoretically analyzed and verified through simulations and a low-power experimental circuit. This control gives excellent performance under various load conditions, and it is especially effective in reducing load injected harmonics.

Atsuo Kawamura; Richard Hoft

1984-01-01

130

A theory of double hysteresis for ferroelectric crystals  

Microsoft Academic Search

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

N. Srivastava; G. J. Weng

2006-01-01

131

A Micromechanics-Based Hysteresis Model for Ferroelectric Ceramics  

Microsoft Academic Search

Based on the mechanics of domain switch and irreversible thermodynamics, a micromechanics-based model that incorporates the effect of polarization strain and electric polarization in the switched domain is developed to predict the evolution of new domain and the associated hysteresis loops of a ferroelectric ceramic. The new domain concentration cr associated with the remanent polarization Pr, and the new domain

J. Li; G. J. Weng

2001-01-01

132

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

133

Why do hysteresis loops stabilise in a few runs?  

NASA Astrophysics Data System (ADS)

Hysteresis loops of ferromagnets are usually stabilised after four or five field cycles. A tentative explanation is given in the spirit of learning models of spin glasses. It is suggested that loops approach their limit like 2-n, due to the binary nature of magnetic elements (Preisach grains).

Porteseil, J. L.

1987-04-01

134

Hysteresis in Copolymers of Vinylidene Fluoride and Trifluoroethylene.  

National Technical Information Service (NTIS)

Copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE), with more than 50 mole percent VDF exhibit D-E hysteresis loops at room temperature which are much sharper than those exhibited by various crystal phases of the PVDF homopolymer. For th...

G. T. Davis M. G. Broadhurst A. J. Lovinger T. Furukawa

1984-01-01

135

Hysteresis in copolymers of vinylidene fluoride and trifluoroethylene  

Microsoft Academic Search

Copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE), with more than 50 mole percent VDF exhibit D-E hysteresis loops at room temperature which are much sharper than those exhibited by various crystal phases of the PVDF homopolymer. For the copolymer samples investigated here, appreciable conductivity develops at elevated temperatures which in the presence of electric fields leads to trapped charges

G. T. Davis; M. G. Broadhurst; A. J. Lovinger; T. Furukawa

1984-01-01

136

Hysteresis in swelling and in sorption of wood tissue.  

PubMed

The swelling and shrinkage of four Picea abies (L. Karst) wood tissue homogeneous samples, of porosity varying between 45% and 78%, is documented with high-resolution synchrotron radiation phase-contrast X-ray tomographic microscopy. We report measurements of the reversible moisture-induced orthotropic swelling/shrinkage strains. Hysteresis is observed when the swelling/shrinkage strain is considered as a function of relative humidity, except for the very high porosity sample. Hysteresis is no longer present when swelling/shrinkage strains are considered versus moisture content, indicating that wood deforms to the same extent whether an amount of moisture is desorbed or adsorbed. Furthermore, swelling anisotropy, in the tangential and radial directions, is found to increase with increasing porosity. The most homogeneous behaviour for a group of cells is found for 30-50 cells, smaller/larger groups having higher orders of variations. PMID:23523731

Patera, Alessandra; Derome, Dominique; Griffa, Michele; Carmeliet, Jan

2013-03-21

137

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

138

Domain-wall motion in random potential and hysteresis modeling  

SciTech Connect

Two different approaches to hysteresis modeling are compared using a common ground based on energy relations, defined in terms of dissipated and stored energy. Using the Preisach model and assuming that magnetization is mainly due to domain-wall motion, one can derive the expression of magnetization along a major loop typical of the Jiles{endash}Atherton model and then extend its validity to cases where mean-field effects and reversible contributions are present. {copyright} {ital 1998 American Institute of Physics.}

Pasquale, M.; Basso, V.; Bertotti, G. [IEN Galileo Ferraris and INFM C. so M. DAzeglio42, 10125Torino (Italy); Jiles, D.C.; Bi, Y. [Ames Laboratory, Iowa State University, 50011Ames, Iowa (United States)

1998-06-01

139

Negative resistance and anomalous hysteresis in a collective molecular motor  

PubMed

A spatially extended model for a collective molecular motor is presented. The system is driven far from equilibrium by a quenched additive noise. As a result, it exhibits anomalous transport properties, namely, negative resistance and a clockwise hysteresis cycle. The phase diagram and the region of negative resistance are calculated using a Weiss mean field theory. Intuitive explanations of the anomalous transport properties as well as details of its energetics are given. PMID:11088302

Buceta; Parrondo; Van Den Broeck C; de La Rubia FJ

2000-06-01

140

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

141

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

142

Hysteresis compensation for a piezoelectric fiber optic voltage sensor  

NASA Astrophysics Data System (ADS)

We present details of numerical techniques developed to compensate the effects of hysteresis experienced by a hybrid piezoelectric fiber optic voltage sensor. The techniques, implemented using a real-time signal processing system, are tested and their effectiveness evaluated experimentally. The best of the proposed algorithms provides phase error compensation from approximately 7 to nearly 0 deg, and allows us to perform sensor calibration to achieve accuracy better than 0.5% (full scale output).

Fusiek, G.; Niewczas, Pawel; Dziuda, L.; McDonald, James R.

2005-11-01

143

Hysteresis and slow drift in abducens unit activity.  

PubMed

Two trained monkeys made saccadic eye movements to a small visual target. The activity of 39 isolated abducens units, presumed to be motoneurons or abducens internuclear neurons, was recorded in relation to these eye movements. After a calibration trial, a test trial repeatedly elicited 20 degrees horizontal saccades to primary position from either the left or right. On average, the steady-state firing rate at primary position depended on the direction of the saccade. For saccades where the neuron showed a burst in activity during the saccade (on-saccades) the steady-state firing rates were usually higher than for those saccades that showed a pause in activity during the saccade (off-saccades). For the population of units this hysteresis measured 5.4 spikes/s, which may be compared with an average primary-position rate of 97 spikes/s. The average hysteresis for individual units ranged from -2.1 to 18.5 spikes/s. The steady-state firing rate after equal saccades in the same direction and ending at the same position (primary) varied slowly over time. Across all units the variability (standard deviation) ranged from 0.5 to 11.8 spikes/s with a mean of 4.7 spikes/s. Furthermore, for any one unit the variations following on-saccades generally correlated with the variations following the off-saccades. Hysteresis, doubted by many, does exist. Fortunately, it is small enough, 5.5% of typical primary-position rate, that it can be neglected for many purposes. Nevertheless, it poses the interesting theoretical question of how the oculomotor system compensates for hysteresis. The simplest explanation of slow variations in background rate is cocontractive noise: a slow fluctuation in all abducens neurons so that these variations do not result in fluctuations of eye position. PMID:3711966

Goldstein, H P; Robinson, D A

1986-05-01

144

Using stormwater hysteresis to characterize karst spring discharge.  

PubMed

Discharge from karst springs contains a mixture of conduit and matrix water, but the variations in groundwater mixing are poorly known. Storm events present an opportunity to try to map flow components because water entering during storms is more dilute and provides a tracer as it mixes with pre-event water along the flowpath from the recharge area to discharge at a spring. We used hysteresis plots of Mg/Ca ratios in a spring in the Cumberland Valley of Pennsylvania to map conduit (higher Ca) vs. diffuse (higher Mg) sources of recharge. We observed two types of temporal heterogeneity: within a storm event and from storm to storm. The timing of the variation in Mg/Ca suggested sources of mixing waters. An increase in the Mg/Ca ratio at the beginning of some storms while conductivity declined suggested diffuse recharge through the epikarst. The rapid changes in Mg/Ca ratios for low-intensity events probably occurred as the rainfall waxed and waned and illustrate that a variety of flowpaths are available at this spring because additional flushing of Mg occurred. In contrast, the conductivity hysteresis began with dilute water initially and rotation was similar from storm to storm. Hysteresis plots of the Mg/Ca ratio have the potential of revealing more of the complexity in discharge than conductivity alone. A better understanding of flow components in karst is needed to protect these aquifers as a groundwater resource. PMID:22974348

Toran, Laura; Reisch, Chad E

2012-09-13

145

Formulation of capillary hysteresis with internal state variables  

NASA Astrophysics Data System (ADS)

A thermodynamically consistent framework is proposed for modeling the hysteresis of capillarity in partially saturated porous media. Capillary hysteresis is viewed as an intrinsic dissipation mechanism, which can be characterized by a set of internal state variables. The volume fractions of pore fluids are assumed to be additively decomposed into a reversible part and an irreversible part. The irreversible part of the volumetric moisture content is introduced as one of the internal variables. It is shown that the pumping effect occurring in a porous medium experiencing a wetting/drying cycle is thermodynamically admissible. A generic evolution equation for internal variables is developed. By virtue of the notion of the bounding surface plasticity, a model of capillary hysteresis is developed, which is capable of predicting all types of (primary, secondary, and higher-order) scanning curves within the boundary loop. Provided that the main wetting curve and the main drying curve have been experimentally determined, the proposed model requires only one additional parameter to describe all the scanning curves. The model predictions are compared with experimental measurements found in the literature, showing that the new model is capable of describing the capillary hysteretic phenomena in a variety of partially saturated porous materials.

Wei, Changfu; Dewoolkar, Mandar M.

2006-07-01

146

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

2008-10-09

147

Does adsorption in a single nanogroove exhibit hysteresis?  

NASA Astrophysics Data System (ADS)

A simple fluid, in a microscopic capillary capped at one end, is studied by means of fundamental measure density functional. The model represents a single, infinitely long nanogroove with long-range wall-fluid attractive (dispersion) forces. It is shown that the presence or absence of hysteresis in adsorption isotherms is determined by wetting properties of the wall as follows: Above wetting temperature, Tw, appropriate to a single wall of the groove, the adsorption is a continuous process corresponding to a rise of a meniscus from the capped to the open end of the groove. For a sufficiently deep capillary, the meniscus rise is shown to be a steep, yet continuous process taking place near the capillary condensation of a corresponding slit. However, for temperatures lower than Tw the condensation exhibits a first-order transition accompanied by hysteresis of the adsorption isotherm. Finally, it is shown that hysteresis may occur even for T > Tw as a consequence of prewetting on the side and bottom walls of the groove.

Malijevský, Alexandr

2012-12-01

148

Neural networks based identification and compensation of rate-dependent hysteresis in piezoelectric actuators  

NASA Astrophysics Data System (ADS)

This paper presents a method of the identification for the rate-dependent hysteresis in the piezoelectric actuator (PEA) by use of neural networks. In this method, a special hysteretic operator is constructed from the Prandtl-Ishlinskii (PI) model to extract the changing tendency of the static hysteresis. Then, an expanded input space is constructed by introducing the proposed hysteretic operator to transform the multi-valued mapping of the hysteresis into a one-to-one mapping. Thus, a feedforward neural network is applied to the approximation of the rate-independent hysteresis on the constructed expanded input space. Moreover, in order to describe the rate-dependent performance of the hysteresis, a special hybrid model, which is constructed by a linear auto-regressive exogenous input (ARX) sub-model preceded with the previously obtained neural network based rate-independent hysteresis sub-model, is proposed. For the compensation of the effect of the hysteresis in PEA, the PID feedback controller with a feedforward hysteresis compensator is developed for the tracking control of the PEA. Thus, a corresponding inverse model based on the proposed modeling method is developed for the feedforward hysteresis compensator. Finally, both simulations and experimental results on piezoelectric actuator are presented to verify the effectiveness of the proposed approach for the rate-dependent hysteresis.

Zhang, Xinliang; Tan, Yonghong; Su, Miyong; Xie, Yangqiu

2010-06-01

149

Evaluation of minor hysteresis loops using Langevin transforms in modified inverse Jiles-Atherton model  

NASA Astrophysics Data System (ADS)

In this paper, we present a Langevin transforms model which evaluates accurately minor hysteresis loops for the modified inverse Jiles-Atherton model by using appropriate expressions in order to improve minor hysteresis loops characteristics. The parameters of minor hysteresis loops are then related to the parameters of the major hysteresis loop according to each level of maximal induction by using Langevin transforms expressions. The stochastic optimization method "simulated annealing" is used for the determination of the Langevin transforms coefficients. This model needs only two experimental tests to generate all hysteresis loops. The validity of the Langevin transforms model is justified by comparison of calculated minor hysteresis loops to measured ones and good agreements are obtained with better results than the exponential transforms model (Hamimid et al., 2011 [4]).

Hamimid, M.; Mimoune, S. M.; Feliachi, M.

2013-11-01

150

Effect of contact angle hysteresis on water droplet evaporation from super-hydrophobic surfaces  

Microsoft Academic Search

Small water drops demonstrate different evaporation modes on super-hydrophobic polymer surfaces with different hysteresis of contact angle. While on the high-hysteresis surface evaporation follows the constant-contact-diameter mode, the constant-contact-angle mode dominates on the low-hysteresis surface. These modes were previously reported for smooth hydrophilic and hydrophobic surfaces, respectively. The experimental data are compared to the previous models describing spherical cap drops

S. A. Kulinich; M. Farzaneh

2009-01-01

151

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

152

Magnetic hysteresis and refrigeration capacity of Ni-Mn-Ga alloys near Martensitic transformation  

Microsoft Academic Search

This paper studies the magnetic hysteresis and refrigeration capacity of Ni-Mn-Ga alloys in detail during heating and cooling isothermal magnetisation processes. The Ni-Mn-Ga alloys show larger magnetic hysteresis when they transform from austenite to martensite, but smaller magnetic hysteresis when they transform from martensite to austenite. This behaviour is independent of either the pure Ni-Mn-Ga alloys or the alloys doped

Bin Fu; Yi Long; Jing-Fang Duan; Chao-Lun Wang; Yong-Qin Chang; Rong-Chang Ye; Guang-Heng Wu

2010-01-01

153

Ultralow hysteresis superhydrophobic surfaces by excimer laser modification of SU-8.  

PubMed

We present a new and simple method to produce superhydrophobic surfaces with ultralow hysteresis. The method involves surface modification of SU-8 using an excimer laser treatment. The modified surface is coated with a hydrophobic plasma-polymerized hexafluoropropene layer. The advancing and receding water contact angles were measured to be approximately 165 degrees . The achieved water contact angle hysteresis was below the measurement limit. This low hysteresis can be ascribed to nanoscale debris generated during the excimer laser process. PMID:17154561

Wagterveld, R Martijn; Berendsen, Christian W J; Bouaidat, Salim; Jonsmann, Jacques

2006-12-19

154

Quenching of giant hysteresis effects in La1-zYzHx switchable mirrors  

Microsoft Academic Search

The giant intrinsic hysteresis as a function of hydrogen concentration x in the optical and electrical properties of the archetypal switchable mirror YHx is eliminated by alloying Y with the chemically similar La. The La1-zYzHx films with z?0.67 are essentially hysteresis-free. The origin of the large hysteresis of alloys with z?0.86 is the large uniaxial lattice expansion that accompanies their

Gogh van A. T. M; D. G. Nagengast; E. S. Kooij; N. J. Koeman; R. P. Griessen

2000-01-01

155

An artificial hysteresis binary neuron: a model suppressing the oscillatory behaviors of neural dynamics  

Microsoft Academic Search

A hysteresis binary McCulloch-Pitts neuron model is proposed in order to suppress the complicated oscillatory behaviors of neural dynamics. The artificial hysteresis binary neural network is used for scheduling time-multiplex crossbar switches in order to demonstrate the effects of hysteresis. Time-multiplex crossbar switching systems must control traffic on demand such that packet blocking probability and packet waiting time are minimized.

Y. Takefuji; K. C. Lee

1991-01-01

156

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

157

Element-specific magnetic hysteresis measurements, a new application of circularly polarized soft x-rays  

SciTech Connect

Element-specific magnetic hysteresis measurements on heteromagnetic materials have been achieved by using circularly polarized soft-x- rays. Dramatically different Fe and Co hysteresis curves of Fe/Cu/Co trilayers were obtained by recording the magnetic circular dichroism (MCD) at their respective L{sub 3} white lines as a function of applied magnetic field. The data resolve the complicated hysteresis curves, observed by conventional magnetometry, and determine the individual magnetic moments for the Fe and Co layers. Fine hysteresis features, imperceptible in the conventional curves, were also observed, demonstrating a new application of circularly polarized soft-x-rays in the investigation of magnetic systems.

Lin, H.J.; Chen, C.T.; Meigs, G. [AT and T Bell Labs., Murray Hill, NJ (United States); Idzerda, Y.U.; Chaiken, A.; Prinz, G.A. [Naval Research Lab., Washington, DC (United States); Ho, G.H. [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Physics

1993-09-07

158

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

159

Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range  

NASA Astrophysics Data System (ADS)

Piezoelectric actuators exhibit large hysteresis between the applied voltage and their displacement. A switched capacitor charge pump is proposed to reduce hysteresis and linearize the movement of piezoelectric actuators. By pumping the same amount of charges into the piezoelectric actuator quantitatively, the actuator will be forced to change its length with constant step. Compared with traditional voltage and charge driving, experimental results demonstrated that the piezoelectric stack driven by the charge pump had less hysteresis over a large frequency range, especially at ultralow frequencies. A hysteresis of less than 2.01% was achieved over a frequency range of 0.01-20 Hz using the charge pump driver.

Huang, Liang; Ma, Yu Ting; Feng, Zhi Hua; Kong, Fan Rang

2010-09-01

160

Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range.  

PubMed

Piezoelectric actuators exhibit large hysteresis between the applied voltage and their displacement. A switched capacitor charge pump is proposed to reduce hysteresis and linearize the movement of piezoelectric actuators. By pumping the same amount of charges into the piezoelectric actuator quantitatively, the actuator will be forced to change its length with constant step. Compared with traditional voltage and charge driving, experimental results demonstrated that the piezoelectric stack driven by the charge pump had less hysteresis over a large frequency range, especially at ultralow frequencies. A hysteresis of less than 2.01% was achieved over a frequency range of 0.01-20 Hz using the charge pump driver. PMID:20886997

Huang, Liang; Ma, Yu Ting; Feng, Zhi Hua; Kong, Fan Rang

2010-09-01

161

Fabrication of surfaces with extremely high contact angle hysteresis from polyelectrolyte multilayer.  

PubMed

High contact angle hysteresis on polyelectrolyte multilayers (PEMs) ion-paired with hydrophobic perfluorooctanoate anions is reported. Both the bilayer number of PEMs and the ionic strength of deposition solutions have significant influence on contact angle hysteresis: higher ionic strength and greater bilayer number cause increased contact angle hysteresis values. The hysteresis values of ~100° were observed on smooth PEMs and pinning of the receding contact line on hydrophilic defects is implicated as the cause of hysteresis. Surface roughness can be used to further tune the contact angle hysteresis on the PEMs. A surface with extremely high contact angle hysteresis of 156° was fabricated when a PEM was deposited on a rough substrate coated with submicrometer scale silica spheres. It was demonstrated that this extremely high value of contact angle hysteresis resulted from the penetration of water into the rough asperities on the substrate. The same substrate hydrophobized by chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltriethoxysilane exhibits high advancing contact angle and low hysteresis. PMID:22044032

Wang, Liming; Wei, Jingjing; Su, Zhaohui

2011-11-16

162

Drift and deformation of the hysteresis curve in thin film ferroelectric capacitors with conductance  

NASA Astrophysics Data System (ADS)

In this paper, the contribution of leakage to the hysteresis curve in thin film ferroelectric capacitors is analysed quantitatively by applying a very simple circuit model and experiment. Based on our previous analysis of current - voltage characteristics in thin film ferroelectric capacitors, the deformed hysteresis loops due to leakage are calculated with respect to various barriers and frequencies, and are verified with our laser ablated 0022-3727/29/7/040/img7 thin film capacitors. Some interesting phenomena, such as gap in hysteresis curves, vertical drift of hysteresis loops, etc, are discussed.

Zheng, Lirong; Lin, Chenglu; Xu, W.-ping; Okuyama, Masanori

1996-07-01

163

Hysteresis phenomenon in the galloping oscillation of a square cylinder  

NASA Astrophysics Data System (ADS)

It is well known that a square cylinder with one side normal to a uniform stream will gallop when a critical flow velocity is exceeded. It is also quite well known that there is a hysteresis phenomenon in the variation of the cylinder's galloping amplitude with the flow velocity. However, little is known about the cause of this hysteresis phenomenon, and the objective of this paper is to study it more closely. In the present study, flow over a stationary square cylinder at different angle of attack (/?) and at Reynolds number (Re) of 250 and 1000 was investigated numerically by using a 2-D hybrid vortex computation scheme. The study reveals that the well known point of inflection which exists in the side force (Cy) versus /? plots at high Reynolds number only occurs at Re=1000, /?=4° in the present numerical simulation. Nonlinear analysis further reveals that this point of inflection is the cause of the hysteresis phenomenon. By further analysing the computed flow field, it is noted that at Re=1000, /?=4°, intermittent flow reattachment takes place at alternate vortex shedding cycle on one side of the cylinder. This results in larger side force fluctuation, and it is conjectured that such large side force fluctuation affects the increasing trend of the side force with angle of attack, resulting in the point of inflection reported earlier. The above-mentioned alternate cycle flow reattachment was much less prominent at /?=2° and 6° (Re=1000), and was not observed at Re=250. Finally, dye flow visualization was carried out in a recirculating water tunnel and the results at Re=1000 confirms the existence of the intermittent flow reattachment. However, in the experiment, flow reattachment does not take place in a very regular alternate cycle manner as in the computation. Instead, it occurs intermittently, possibly due to three-dimensional effects in real flow.

Luo, S. C.; Chew, Y. T.; Ng, Y. T.

2003-08-01

164

Stability of Soap Films: Hysteresis and Nucleation of Black Films  

NASA Astrophysics Data System (ADS)

We study the stability of soap films of a nonionic surfactant under different applied capillary pressures on the film. Depending on the pressure, either a thick common black film (CBF), or a micro­scopically thin Newton black film (NBF) is formed as a (metastable) equilibrium state, with a first-order (discontinuous) transition between the two. Studying the dynamics of the CBF-NBF transition, it is found that under certain conditions a hysteresis for the transition is observed: for a given range of pressures, either of the two states may be observed. We quantify the nucleation process that is at the basis of these observations both experimentally and theoretically.

Casteletto, Valeria; Cantat, Isabelle; Sarker, Dipak; Bausch, Richard; Bonn, Daniel; Meunier, Jacques

2003-01-01

165

Stability of soap films: hysteresis and nucleation of black films.  

PubMed

We study the stability of soap films of a nonionic surfactant under different applied capillary pressures on the film. Depending on the pressure, either a thick common black film (CBF), or a micro-scopically thin Newton black film (NBF) is formed as a (metastable) equilibrium state, with a first-order (discontinuous) transition between the two. Studying the dynamics of the CBF-NBF transition, it is found that under certain conditions a hysteresis for the transition is observed: for a given range of pressures, either of the two states may be observed. We quantify the nucleation process that is at the basis of these observations both experimentally and theoretically. PMID:12570466

Casteletto, Valeria; Cantat, Isabelle; Sarker, Dipak; Bausch, Richard; Bonn, Daniel; Meunier, Jacques

2003-01-30

166

Adsorption hysteresis in self-ordered nanoporous alumina.  

PubMed

We performed systematic adsorption studies using self-ordered nanoporous anodic aluminum oxide (AAO) in an extended range of mean pore diameters and with different pore topologies. These matrices were characterized by straight cylindrical pores having a narrow pore size distribution and no interconnections. Pronounced hysteresis loops between adsorption and desorption cycles were observed even in the case of pores closed at one end. These results are in contrast with macroscopic theoretical models and detailed numerical simulations of the adsorption in a single pore. Extensive measurements involving adsorption isotherms, reversal curves, and subloops carried out in closed-bottom pores suggest that the pores do not desorb independently from one another. PMID:18729482

Bruschi, Lorenzo; Fois, Giovanni; Mistura, Giampaolo; Sklarek, Kornelia; Hillebrand, Reinald; Steinhart, Martin; Gösele, Ulrich

2008-08-27

167

Mass Measurement System Using Relay Feedback with Hysteresis  

NASA Astrophysics Data System (ADS)

Mass measurement using a relay feedback system was studied experimentally. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle in the feedback system. The mass of the object is determined from the period of this limit cycle. The apparatus manufactured for experimental study uses two voice coil motors (VCM's), one of which is for driving the object and the other is for generating prescribed disturbances. The effects of system parameters and disturbances on measurement accuracy were examined experimentally.

Mizuno, Takeshi; Adachi, Takahiro; Takasaki, Masaya; Ishino, Yuji

168

Hysteresis and charge trapping in graphene quantum dots  

NASA Astrophysics Data System (ADS)

We report current hysteresis in response to applied voltage in graphene quantum dots of average diameter 4.5 +/- 0.55 nm, synthesized electrochemically using multiwalled carbon nanotubes. In response to step voltages, transient current decay, characteristic of deep and shallow level charge traps with time constants 186 ms and 6 s, is observed. Discharging current transients indicate charge storage of the order of 100 ?C. Trap states are believed to arise due to the fast physisorption of external adsorbates, which are found to have a significant effect on charge transport and changes the resistance of the prepared device by an order of 3.

Kalita, Hemen; V, Harikrishnan; Shinde, Dhanraj B.; Pillai, Vijayamohanan K.; Aslam, M.

2013-04-01

169

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

170

Capillary condensation, invasion percolation, hysteresis, and discrete memory  

SciTech Connect

A model of the capillary condensation process, i.e., of adsorption-desorption isotherms, having only pore-pore interactions is constructed. The model yields (1) hysteretic isotherms, (2) invasion percolation on desorption, and (3) hysteresis with discrete memory for interior chemical potential loops. All of these features are seen in experiment. The model is compared to a model with no pore-pore interactions (the Preisach model) and to a related model of interacting pore systems (the random field Ising model). The capillary condensation model differs from both. {copyright} {ital 1996 The American Physical Society.}

Guyer, R.A. [Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003 (United States); McCall, K.R. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)

1996-07-01

171

Hysteresis and bristle stiffening effects of conventional brush seals  

NASA Astrophysics Data System (ADS)

Extensive testing of conventional brush seals has identified the phenomena of bristle 'hysteresis' and 'stiffening' with pressure as their two major drawbacks. Subsequent to any differential movement of the runner into the bristle pack due to its radial excursions or centrifugal/thermal growths, the displaced bristles do not recover against the frictional forces between them and the backing plate. As a result, a significant leakage increase is observed following any runner movement. Furthermore, the bristle pack exhibits a considerable stiffening effect with the application of pressure. This phenomenon adversely affects the life of the seal and the runner due to a highly increased mechanical contact pressure at the sliding interface. In comparison with these conventional design seals, the characteristics of an improved design, known as the 'low hysteresis' design, are presented here. This design shows a substantially lower degree of the detrimental effects mentioned above. This type of seal can maintain its reduced leakage characteristics throughout the running cycle with runner excursions and growths. The bristles also do not show any stiffening, up to a certain pressure threshold. Therefore, this seal also has a potential for a longer life than a brush seal of conventional design.

Basu, P.; Datta, A.; Johnson, R.; Loewenthal, R.; Short, J.

1993-06-01

172

Low frequency hysteresis loops of superparamagnetic nanoparticles with uniaxial anisotropy  

NASA Astrophysics Data System (ADS)

The low frequency hysteresis loops of superparamagnetic nanoparticles with uniaxial anisotropy are calculated as a function of the particle diameter, alternating magnetic field amplitude H0, frequency, and particle magnetic parameters both for oriented and nonoriented assemblies. The magnetic field frequency is assumed so high, f>50-100 kHz, that the mechanical rotation of a particle in surrounding medium is restricted. Thus, only the Neel-Brown magnetization relaxation process is taken into account. Pronounced dependence of the specific loss power on the particle diameter is found in the linear regime pertaining to small magnetic field amplitudes. For an oriented assembly of Co nanoparticles with optimal diameter D~6 nm the specific power loss can be as high as 1600 W/g for typical values H0=200 Oe and f=500 kHz. It is three times less for the corresponding nonoriented assembly. Nevertheless, using of particles with low anisotropy field, i.e., particles of soft magnetic type, seems to be preferable for the purpose of magnetic nanoparticle hyperthermia. For such an assembly the nonlinear regime can be easily accessed. Hence the hysteresis loop area increases and is comparable with its maximum possible value.

Usov, N. A.

2010-06-01

173

Computational micromagnetic study of particulate media hysteresis and recording  

NASA Astrophysics Data System (ADS)

A description of the micromagnetic theory, algorithms, computer software and computer hardware built and used to study particulate media particles, hysteresis and recording is first provided. This includes a derivation and analysis of the modified version of the Fast Multipole Method used in this dissertation. Results will then be presented on particulate media particle nucleation field dependence on particle shape, particle aspect ratio, ferromagnetic exchange energy and external magnetic field angle. Results on the discretization necessary to accurately model a particle will also be provided. The reversal mode of a particle will be simulated and analyzed. Simulated longitudinal and transverse hysteresis loops will be presented. Results will also be presented on particulate media coercivity and squareness dependence on volumetric packing fraction. Simulated recorded transition results will be given as well as total power spectra results for AC and DC erased particulate media. Numerical results will be compared to experimental data and analytical theories. Advice is provided on how to build a personal supercomputer like the one used in the numerical experiments of this dissertation.

Seberino, Christian

2000-11-01

174

Application of the Preisach Model to Soil-moisture Hysteresis  

NASA Astrophysics Data System (ADS)

An examination of the physics of the land phase of the hydrological cycle shows that the most important non-linearities occur in the unsaturated zone of the soil. These have been studied using switched boundary conditions applied to the one-dimensional form of Richards differential equation, modelling the wetting and drying of a column of bare or vegetated soil, at a scale of roughly one meter. However, the strongly non-linear hysteretic property of the soil moisture characteristic is usually ignored. Smooth non-linear differential, or integro-differential, operators cannot reproduce soil-moisture hysteresis. The classical Preisach Model is presented and applied to the quantitative description of soil-moisture scanning curves. The Preisach model is a deterministic, rate independent non-linear operator with return-point memory and congruent loops. Special, one parameter, classes of Preisach operators are proposed as models of soil-moisture hysteresis for particular soils. The results of fitting these operators to laboratory and field data, taken from the Grenoble GRIZZLY Soil Database, are presented and discussed.

O'Kane, J.; Pokrovskii, A.; Krejci, P.; Haverkamp, R.

2003-12-01

175

The capillary hysteresis model HYSTR: User`s guide  

SciTech Connect

The potential disposal of nuclear waste in the unsaturated zone at Yucca Mountain, Nevada, has generated increased interest in the study of fluid flow through unsaturated media. In the near future, large-scale field tests will be conducted at the Yucca Mountain site, and work is now being done to design and analyze these tests. As part of these efforts a capillary hysteresis model has been developed. A computer program to calculate the hysteretic relationship between capillary pressure {phi} and liquid saturation (S{sub 1}) has been written that is designed to be easily incorporated into any numerical unsaturated flow simulator that computes capillary pressure as a function of liquid saturation. This report gives a detailed description of the model along with information on how it can be interfaced with a transport code. Although the model was developed specifically for calculations related to nuclear waste disposal, it should be applicable to any capillary hysteresis problem for which the secondary and higher order scanning curves can be approximated from the first order scanning curves. HYSTR is a set of subroutines to calculate capillary pressure for a given liquid saturation under hysteretic conditions.

Niemi, A.; Bodvarsson, G.S.

1991-11-01

176

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

177

Hysteresis and phase transition in many-particle storage systems  

NASA Astrophysics Data System (ADS)

We study the behavior of systems that can be described as ensembles of interconnected storage particles. Our examples concern the storage of lithium in many-particle electrodes of rechargeable lithium-ion batteries and the storage of air in a system of interconnected rubber balloons. We are particularly interested in those storage systems whose constituents exhibit non-monotone material behavior leading to transitions between two coexisting phases and to hysteresis. In the current study, we consider the case that the time to approach equilibrium of a single storage particle is much smaller than the time for full charging of the ensemble. In this regime, the evolution of the probability to find a particle of the ensemble in a certain state may be described by a non-local conservation law of Fokker-Planck type. The resulting equation contains two parameter which control whether the ensemble transits the 2-phase region along a Maxwell line or along a hysteresis path, or whether the ensemble shows the same non-monotone behavior as its constituents.

Dreyer, Wolfgang; Guhlke, Clemens; Herrmann, Michael

2011-05-01

178

Comparative analysis of fixed and sinusoidal band hysteresis current controllers for voltage source inverters  

Microsoft Academic Search

A hysteresis controller with a sinusoidal band for current regulation is described. The behavior of the conventional fixed-band controller and the proposed sinusoidal band controller has been thoroughly studied. Simulation results demonstrate that with no lockout (permitting a very high switching frequency) the current waveform can be confined within the desired hysteresis bands. At low lockout frequencies the current is

Ajay Tripathi; Paresh C. Sen

1992-01-01

179

Adaptive Neural Network Control of Hard Disk Drives With Hysteresis Friction Nonlinearity  

Microsoft Academic Search

In this brief, an adaptive neural network (NN) fric- tion compensator is presented for servo control of hard disk drives (HDDs). The existence of the hysteresis friction nonlinearity from pivot bearing, which is represented as the LuGre hysteresis fric- tion model here, increases the position error signal of read-write head and deteriorates the performance of HDD servo systems. To compensate

Phyo Phyo San; Beibei Ren; Shuzhi Sam Ge; Tong Heng Lee; Jin-Kun Liu

2011-01-01

180

Effects of size distribution on hysteresis losses of magnetic nanoparticles for hyperthermia  

Microsoft Academic Search

For understanding hysteresis losses of magnetic nanoparticles to be used for magnetic particle hyperthermia the effect of size distribution on the dependence of hysteresis losses on magnetic field amplitude is studied on the basis of a phenomenological model in the size range from superparamagnetism to magnetic multi-domains---roughly 10 up to 100 nm. Relying on experimental data for the size dependence

Rudolf Hergt; Silvio Dutz; Michael Röder

2008-01-01

181

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

182

Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range  

Microsoft Academic Search

Piezoelectric actuators exhibit large hysteresis between the applied voltage and their displacement. A switched capacitor charge pump is proposed to reduce hysteresis and linearize the movement of piezoelectric actuators. By pumping the same amount of charges into the piezoelectric actuator quantitatively, the actuator will be forced to change its length with constant step. Compared with traditional voltage and charge driving,

Liang Huang; Yu Ting Ma; Zhi Hua Feng; Fan Rang Kong

2010-01-01

183

Self-Induced Hysteresis for Nonlinear Acoustic Waves in Cracked Material  

Microsoft Academic Search

A new phenomenon of self-induced hysteresis has been observed in the interaction of bulk acoustic waves with a cracked solid. It consists in a hysteretic behavior of material nonlinearity as a function of the incident pump wave amplitude. Hysteresis manifests itself in the self-action of the monochromatic pump wave and in the excitation of its superharmonics and of its subharmonics.

Alexei Moussatov; Vitalyi Gusev; Bernard Castagnède

2003-01-01

184

Experimental and theoretical study of spontaneous spin polarization and hysteresis in cesium vapor  

Microsoft Academic Search

We report results of measurements and theoretical modeling of spontaneous spin polarization and associated hysteresis in an optically pumped Cs vapor. We observe hysteresis over the full range (20-450 torr) of N2 buffer gas pressures tested, and on two hyperfine components of the D1 transition, so long as both electronic spin exchange and optical pumping of a resolved ground state

A. Andalkar; R. B. Warrington; M. V. Romalis; S. K. Lamoreaux; B. R. Heckel; E. N. Fortson

2002-01-01

185

Hysteresis and process stability in reactive high power impulse magnetron sputtering of metal oxides  

Microsoft Academic Search

In the further development of reactive sputter deposition, strategies which allow for stabilization of the transition zone between the metallic and compound modes, elimination of the process hysteresis, and increase of the deposition rate, are of particular interest. In this study, the hysteresis behavior and the characteristics of the transition zone during reactive high power impulse magnetron sputtering (HiPIMS) of

Montri Aiempanakit; Tomás Kubart; Petter Larsson; Kostas Sarakinos; Jens Jensen; Ulf Helmersson

2011-01-01

186

Artificial pumping errors in the Kool Parker scaling model of soil moisture hysteresis  

Microsoft Academic Search

Hysteresis models that eliminate the artificial pumping errors associated with the Kool Parker (KP) soil moisture hysteresis model, such as the Parker Lenhard (PL) method, can be computationally demanding in unsaturated transport models since they need to retain the wetting drying history of the system. The pumping errors in these models need to be eliminated for correct simulation of cyclical

Adrian D. Werner; David A. Lockington

2006-01-01

187

Large melting-point hysteresis of Ge nanocrystals embedded in SiO2.  

PubMed

The melting behavior of Ge nanocrystals embedded within SiO2 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. PMID:17155336

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, J W; Chrzan, D C; Haller, E E

2006-10-09

188

Large Melting-Point Hysteresis of Ge Nanocrystals Embedded in SiO2  

Microsoft Academic Search

The melting behavior of Ge nanocrystals embedded within SiO2 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.

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

2006-01-01

189

Improved Multilevel Hysteresis Current Regulation and Capacitor Voltage Balancing Schemes for Flying Capacitor Multilevel Inverter  

Microsoft Academic Search

This paper focuses on the development of multilevel hysteresis current regulation strategies. Two such strategies have been discussed and some modifications in their control tasks have been proposed to achieve more reliable and improved performance. In general, the multiband concept has been used while making the proposals. The hysteresis band size considerations have also been presented by taking into account

Anshuman Shukla; Arindam Ghosh; Avinash Joshi

2008-01-01

190

NON-LINEAR AEROELASTIC ANALYSIS USING THE POINT TRANSFORMATION METHOD, PART 2: HYSTERESIS MODEL  

Microsoft Academic Search

This paper investigates the dynamic response of a two-dimensional aeroelastic system with structural non-linearity represented by hysteresis. The formulations of the point transformation method developed in Part 1 of this study for the aeroelastic system with a freeplay model is extended for a hysteresis model. These formulations can be applied not only to predict the amplitude and frequency of limit

L. LIU; Y. S. WONG; B. H. K. LEE

2002-01-01

191

Prediction of Hysteresis Associated with the Static Stall of an Airfoil  

Microsoft Academic Search

rial. It is caused by massive flow separation resulting in sharp drop in lift and increase in the drag acting on the airfoil. In certain cases, hysteresis in the flow has been observed for angles of attack close to the stall angle. However, this phenomenon is not very well un- derstood. Hoffmannl has reported the hysteresis loop in the data

S. Mittal; P. Saxena

2000-01-01

192

Hysteresis of electrocardiographic depolarization–repolarization intervals during dynamic physical exercise and subsequent recovery  

Microsoft Academic Search

The post-exercise electrocardiographic QT interval is shortened relative to that at similar heart rates during exercise or pre-exercise rest. This lag in QT adaptation to the recovering heart rate is described as ‘hysteresis’. No previous studies have quantified the influence of ECG electrode placement on hysteresis following physical exercise. Six males and six females of similar age, mass and aerobic

M J Lewis; A L Short

2006-01-01

193

Quantitative evaluation of magnet hysteresis effects at LANSCE with respect to magnet power supply specifications  

Microsoft Academic Search

The proton beam in the LANSCE accelerator is guided and focused almost exclusively by electromagnets. Magnet hysteresis has had significant impacts on the tuning of the LANSCE accelerator. Magnet hysteresis can also have an impact on magnet power supply (MPS) control, regulation and repeatability requirements. To date, MPS performance requirements have been driven by the requirements on the magnetic fields

J. Bradley; W. Roybal; W. Reass; J. Sandoval; M. Fresquez; L. Fernandez; C. Andrews

2007-01-01

194

Characterization of static hysteresis models using first-order reversal curves diagram method  

NASA Astrophysics Data System (ADS)

First-Order Reversal Curves (FORC) diagram method is known as a non-parametrical identification method for the Classical Preisach Model. However, the FORC diagram is used for material characterization and can be simulated by any hysteresis model. In this paper we analyze the possibility to use FORC diagrams for the identification of the hysteresis models parameters and the limits of this approach.

Stancu, Alexandru; Andrei, Petru

2006-02-01

195

First-order phase transition and anomalous hysteresis of Bose gases in optical lattices  

NASA Astrophysics Data System (ADS)

We study the first-order quantum phase transitions of Bose gases in optical lattices. A special emphasis is placed on an anomalous hysteresis behavior, in which the phase transition occurs in a unidirectional way and a hysteresis loop does not form. We first revisit the hardcore Bose-Hubbard model with dipole-dipole interactions on a triangular lattice to analyze accurately the ground-state phase diagram and the hysteresis using the cluster mean-field theory combined with cluster-size scaling. Details of the anomalous hysteresis are presented. We next consider the two-component and spin-1 Bose-Hubbard models on a hypercubic lattice and show that the anomalous hysteresis can emerge in these systems as well. In particular, for the former model, we discuss the experimental feasibility of the first-order transitions and the associated hysteresis. We also explain an underlying mechanism of the anomalous hysteresis by means of the Ginzburg-Landau theory. From the given cases, we conclude that the anomalous hysteresis is a ubiquitous phenomenon of systems with a phase region of lobe shape that is surrounded by the first-order boundary.

Yamamoto, Daisuke; Ozaki, Takeshi; Sá de Melo, Carlos A. R.; Danshita, Ippei

2013-09-01

196

Medium strain hysteresis loss of natural rubber and styrene-butadiene rubber vulcanizates: a predictive model  

Microsoft Academic Search

A model for hysteresis loss of rubber vulcanizates at medium strain (less than 100%) under dynamic condition has been proposed by using Boltzmann superposition principle, statistical theory of rubber elasticity and phenomenological theory. The theory incorporates both experimental and analytical parameters to quantify hysteresis loss. The model with no adjustment parameter has been successfully tested using the experimental results for

Kamal K. Kar; Anil K. Bhowmick

1999-01-01

197

Characteristics of PWM inverter-driven hysteresis motor with short-duration overexcitation  

Microsoft Academic Search

This paper presents the characteristics of PWM inverter-driven hysteresis motor with short-duration overexcitation. When voltage changes to a step form etc., the change of the rotational speed of hysteresis motor and the change of input current are clarified especially. It is shown clearly that it is good to make a voltage variable pattern into a trapezoidal wave from an experimental

Tomotsugu Kubota; Kazumi Kurihara; Takahiro Tamura

2010-01-01

198

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

199

A novel hysteresis current controller for multilevel single phase voltage source inverters  

Microsoft Academic Search

The application and benefits of hysteresis current control for two level voltage source inverters are well understood, but the extension of the strategy to multilevel inverters is much less established. Previous approaches have used either multiple hysteresis bands or a time based lockout strategy to decide when to switch to successive voltage levels, but these approaches are either complex, and\\/or

G. H. Bode; D. N. Zmood; P. C. Loh; D. G. Holmes

2001-01-01

200

Feedback-Linearized Inverse Feedforward for Creep, Hysteresis, and Vibration Compensation in AFM Piezoactuators  

Microsoft Academic Search

In this brief, we study the design of a feedback and feedforward controller to compensate for creep, hysteresis, and vibration effects in an experimental piezoactuator system. First, we linearize the nonlinear dynamics of the piezoactuator by accounting for the hysteresis (as well as creep) using high-gain feedback control. Next, we model the linear vibrational dynamics and then invert the model

Kam K. Leang; Santosh Devasia

2007-01-01

201

Hysteresis Response of Lead Zirconate—Lead Nickel Niobate Ferroelectric Ceramic Under Compressive Stress  

Microsoft Academic Search

In this work, PZ–PNN ceramic was prepared by a columbite method and sintered at optimum temperature. The effect of uniaxial compressive stress on the hysteresis properties of PZ–PNN ceramics is investigated. The hysteresis loop and ferroelectric properties under the compressive stress of the ceramics are observed at stress up to 100 MPa using a compressometer in conjunction with a modified

W. C. Vittayakorn; N. Vittayakorn

2009-01-01

202

Ultralyophobic oxidized aluminum surfaces exhibiting negligible contact angle hysteresis.  

PubMed

Ultralyophobic oxidized aluminum surfaces exhibiting negligible contact angle hysteresis for probe liquids were prepared by chemical vapor deposition (CVD) of bis((tridecafluoro-1,1,2,2,-tetrahydrooctyl)-dimethylsiloxy)methylsilane (CF(3)(CF(2))(5)CH(2)CH(2)Si(CH(3))(2)O)(2)SiCH(3)H, (R(F)Si(Me)(2)O)(2)SiMeH). Oxidized aluminum surfaces were prepared by photooxidation/cleaning of sputter-coated aluminum on silicon wafers (Si/Al(Al(2)(O(3)))) using oxygen plasma. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) confirmed that this facile CVD method produces a monolayer with a thickness of 1.1 nm on the Si/Al(Al(2)(O(3))) surface without a discernible change in surface morphology. After monolayer deposition, the hydrophilic Si/Al(Al(2)(O(3))) surface became both hydrophobic and oleophobic and exhibited essentially no contact angle hysteresis for water and n-hexadecane (advancing/receding contact angles (theta(A)/theta(R)) = 110 degrees/109 degrees and 52 degrees/50 degrees, respectively). Droplets move very easily on this surface and roll off of slightly tilted surfaces, independently of the contact angle (which is a practical definition of ultralyophobic). A conventional fluoroalkylsilane monolayer was also prepared from 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (CF(3)(CF(2))(7)CH(2)CH(2)Si(OCH(3))(3), R(F)Si(OMe)(3)) for comparison. The theta(A)/theta(R) values for water and n-hexadecane are 121 degrees/106 degrees and 76 degrees/71 degrees, respectively. The larger hysteresis values indicate the "pinning" of probe liquids, even though advancing contact angles are larger than those of the (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers. The (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers have excellent hydrolytic stability in water. We propose that the (R(F)Si(Me)(2)O)(2)SiMeH-derived monolayers are flexible and liquidlike and that drops in contact with these surfaces experience very low energy barriers between metastable states, leading to the formation of nonhysteretic ultralyophobic surfaces. PMID:20030348

Hozumi, Atsushi; McCarthy, Thomas J

2010-02-16

203

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

2010-04-11

204

The thermodynamic origin of hysteresis in insertion batteries  

NASA Astrophysics Data System (ADS)

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 1010-1017 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.

Dreyer, Wolfgang; Jamnik, Janko; Guhlke, Clemens; Huth, Robert; Moškon, Jože; Gaberš?ek, Miran

2010-05-01

205

Adhesion hysteresis of a film-terminated fibrillar array  

NASA Astrophysics Data System (ADS)

Motivated by the recent biomimic design of microstructured adhesive surfaces, we study adhesion between a film-terminated fibrillar array and a rigid substrate. Using a two-dimensional model and ignoring the deformation of the fibers and the backing layer, we show that the adhesion behavior is dominated by a dimensionless parameter reflecting the global flexibility of the terminal film. In particular, if the parameter is larger than 0.4, the adhesion is reversible; otherwise one or more hysteresis loops will appear after an approach-retraction cycle, leading to significant increase in the specific separation work. The result is expected to help not only optimal design of the structure, but also other applications such as micro-manipulation in micromechanical systems.

Yan, ShunPing; He, LingHui; Wang, HuiJing

2012-06-01

206

Monte Carlo simulation of the hysteresis phenomena on ferromagnetic nanotubes.  

PubMed

In this work the hysteretic properties of single wall ferromagnetic nanotubes were studied. Hysteresis loops were computed on the basis of a classical Heisenberg model involving nearest neighbor interactions and using a Monte Carlo method implemented with a single spin movement Metropolis dynamics. Nanotubes with square and hexagonal unit cells were studied varying their diameter, temperature and magneto-crystalline anisotropy. Effects of the diameter were found stronger in the square unit cell magnetic nanotubes (SMNTs) than in the hexagonal unit cell magnetic nanotubes (HMNTs). The ferromagnetic behavior was observed in SMNTs at higher temperature than in HMNTs. Moreover in both cases, SMNTs and HMNTs, the magneto-crystalline anisotropy in the longitudinal direction showed a linear correspondence with the coercive field. PMID:22905518

Salazar-Enríquez, C D; Restrepo, J; Restrepo-Parra, E

2012-06-01

207

Hysteresis modelling and compensation for smart sensors and actuators  

NASA Astrophysics Data System (ADS)

The paper outlines the basic features concerning the design of 'embedded' control and compensation algorithms suitable to be employed in smart sensors and actuators, for real time applications. The stringent specifications in such devices require suitable compensation algorithms that can be implemented in cheap and low performance computation units (such as commercial micro-controllers). This paper, starting from a comprehensive analysis of the solutions proposed in recent years for such a task, shows how the capability to describe the behavior of materials having strong magneto-elastic coupling with hysteresis, allows us to employ standard control-based algorithms that are, at the same time, widely effective. The proposed approach is described for actual magnetostrictive actuators.

Visone, C.

2008-11-01

208

Hysteresis and charge dumping in an electron beam  

SciTech Connect

The steady states of an electron beam are studied for a beam moving between electrodes held at identical potentials when charge dumping effects are present. There is a range of parameters for which hysteresis is observed, i.e., the beam may be in either of two states: state I, when all the electrons pass through the system, and state II, when some of the electrons are reflected back by a virtual cathode. There are more electrons in the beam in state II than in state I. At the instant a transition II ..-->.. I occurs, the excess electrons are dumped and a current pulse is produced with amplitude approx.I/sub tot/ and duration approx.tau, where I/sub tot/ and tau are the total current and the electron transit time. Experimental results are reported confirming this charge dumping effect, which may be useful in designing nanosecond electric pulse generators.

Pashchenko, A.V.; Rutkevich, B.N.; Fedorchenko, V.D.; Mazalov, Y.P.

1983-01-01

209

Computation of hysteresis and closure domains in micromagnetism  

NASA Astrophysics Data System (ADS)

In this paper, we report some results obtained in computational micromagnetism, particularly the numerical approximation of hysteresis phenomenon and the numerical approximation of closure domains. We successively consider a brief recall about micromagnetism, a mathematical modelization of a ferromagnetic material by using the total energy functional of the system, a choice of an appropriate functional space and an associated existence theorem, a convenient minimization algorithm based on an augmented Lagrangian method used in combination with an appropriated finite element method. These developments are illustrated upon the study of a piece of a very thin rectangular plate of a ferromagnetic material located in a coplanar unidirectional exterior magnetic field Hest. Under the action of Hest, we compute the internal magnetization of the plate and then, by decreasing step by step the external field from Hmaxex to -Hmaxex, we find back numerically two physical phenomena, the hysterisis and the motion of walls of the closure domains.

Bernadou, Michel J.; He, Song

1998-07-01

210

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

211

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

212

Flexible, low-voltage, and low-hysteresis PbSe nanowire field-effect transistors.  

PubMed

We report low-hysteresis, ambipolar bottom gold contact, colloidal PbSe nanowire (NW) field-effect transistors (FETs) by chemically modifying the silicon dioxide (SiO(2)) gate dielectric surface to overcome carrier trapping at the NW-gate dielectric interface. While water bound to silanol groups at the SiO(2) surface are believed to give rise to hysteresis in FETs of a wide range of nanoscale materials, we show that dehydration and silanization are insufficient in reducing PbSe NW FET hysteresis. Encapsulating PbSe NW FETs in cured poly(methyl) methacrylate (PMMA), dehydrates and uniquely passivates the SiO(2) surface, to form low-hysteresis FETs. Annealing predominantly p-type ambipolar PbSe NW FETs switches the FET behavior to predominantly n-type ambipolar, both with and without PMMA passivation. Heating the PbSe NW devices desorbs surface bound oxygen, even present in the atmosphere of an inert glovebox. Upon cooling, overtime oxygen readsorption switches the FET polarity to predominantly p-type ambipolar behavior, but PMMA encapsulation maintains low hysteresis. Unfortunately PMMA is sensitive to most solvents and heat treatments and therefore its application for nanostructured material deposition and doping is limited. Seeking a robust, general platform for low-hysteresis FETs we explored a variety of hydroxyl-free substrate surfaces, including silicon nitride, polyimide, and parylene, which show reduced electron trapping, but still large hysteresis. We identified a robust dielectric stack by assembling octadecylphosphonic acid (ODPA) on aluminum oxide (Al(2)O(3)) to form low-hysteresis FETs. We further integrated the ODPA/Al(2)O(3) gate dielectric stack on flexible substrates to demonstrate low-hysteresis, low-voltage FETs, and the promise of these nanostructured materials in flexible, electronic circuitry. PMID:22084980

Kim, David K; Lai, Yuming; Vemulkar, Tarun R; Kagan, Cherie R

2011-11-21

213

Implications of NiMH Hysteresis on HEV Battery Testing and Performance  

SciTech Connect

Nickel Metal-Hydride (NiMH) is an advanced high-power battery technology that is presently employed in Hybrid Electric Vehicles (HEVs) and is one of several technologies undergoing continuing research and development by FreedomCAR. Unlike some other HEV battery technologies, NiMH exhibits a strong hysteresis effect upon charge and discharge. This hysteresis has a profound impact on the ability to monitor state-of-charge and battery performance. Researchers at the Idaho National Engineering and Environmental Laboratory (INEEL) have been investigating the implications of NiMH hysteresis on HEV battery testing and performance. Experimental results, insights, and recommendations are presented.

Motloch, Chester George; Belt, Jeffrey R; Hunt, Gary Lynn; Ashton, Clair Kirkendall; Murphy, Timothy Collins; Miller, Ted J.; Coates, Calvin; Tataria, H. S.; Lucas, Glenn E.; Duong, T.Q.; Barnes, J.A.; Sutula, Raymond

2002-08-01

214

Loss separation and parameters for hysteresis modelling under compressive and tensile stresses  

NASA Astrophysics Data System (ADS)

The study of the energy loss in electrical steels is based on the separation of total losses into hysteresis, classical and excess losses according to the statistical theory. In this article, the stress dependence of the hysteresis loss Wh and of the excess loss parameter V0, both related to the microstructure, is investigated for a nonoriented 3% Si-Fe grade under compressive and tensile stress and at plastic deformation. Parameters Wh and V0 for hysteresis and excess losses modeling increase under compression and high plastic tension and decrease under small elastic tension.

Permiakov, Viatcheslav; Dupré, Luc; Pulnikov, Alexandre; Melkebeek, Jan

2004-05-01

215

Hysteresis of thin film IPRTs in the range 100 °C to 600 °C  

NASA Astrophysics Data System (ADS)

As opposed to SPRTs, the IPRTs succumb to hysteresis when submitted to change of temperature. This uncertainty component, although acknowledged as omnipresent at many other types of sensors (pressure, electrical, magnetic, humidity, etc.) has often been disregarded in their calibration certificates' uncertainty budgets in the past, its determination being costly, time-consuming and not appreciated by customers and manufacturers. In general, hysteresis is a phenomenon that results in a difference in an item's behavior when approached from a different path. Thermal hysteresis results in a difference in resistance at a given temperature based on the thermal history to which the PRTs were exposed. The most prominent factor that contributes to the hysteresis error in an IPRT is a strain within the sensing element caused by the thermal expansion and contraction. The strains that cause hysteresis error are closely related to the strains that cause repeatability error. Therefore, it is typical that PRTs that exhibit small hysteresis also exhibit small repeatability error, and PRTs that exhibit large hysteresis have poor repeatability. Aim of this paper is to provide hysteresis characterization of a batch of IPRTs using the same type of thin-film sensor, encapsulated by same procedure and same company and to estimate to what extent the thermal hysteresis obtained by testing one single thermometer (or few thermometers) can serve as representative of other thermometers of the same type and manufacturer. This investigation should also indicate the range of hysteresis departure between IPRTs of the same type. Hysteresis was determined by cycling IPRTs temperature from 100 °C through intermediate points up to 600 °C and subsequently back to 100 °C. Within that range several typical sub-ranges are investigated: 100 °C to 400 °C, 100 °C to 500 °C, 100 °C to 600 °C, 300 °C to 500 °C and 300 °C to 600 °C . The hysteresis was determined at various temperatures by comparison calibration with SPRT. The results of investigation are presented in a graphical form for all IPRTs, ranges and calibration points.

Zvizdi?, D.; Šestan, D.

2013-09-01

216

Quenching of giant hysteresis effects in La(1-z)Y(z)Hx switchable mirrors  

PubMed

The giant intrinsic hysteresis as a function of hydrogen concentration x in the optical and electrical properties of the archetypal switchable mirror YHx is eliminated by alloying Y with the chemically similar La. The La(1-z)Y(z)Hx films with zhysteresis-free. The origin of the large hysteresis of alloys with z>/=0.86 is the large uniaxial lattice expansion that accompanies their fcc to hexagonal phase transition in combination with lateral clamping. PMID:10970486

van Gogh AT; Nagengast; Kooij; Koeman; Griessen

2000-09-01

217

Optical bistability and hysteresis with a photorefractive self-pumped phase conjugate mirror  

Microsoft Academic Search

Bistability and hysteresis have been observed in a photorefractive passive phase conjugate mirror. A threshold basis for the effect is presented along with the results of an experimental demonstration of the device.

S.-K. Kwong; A. Yariv; M. Cronin-Golomb

1984-01-01

218

Effect of Piezoelectric Hysteresis on Helicopter Vibration Control Using Trailing-Edge Flaps  

Microsoft Academic Search

DOI: 10.2514\\/1.17655 Thisstudy investigates the effect of piezoelectric actuator hysteresis onhelicopter vibration control using trailing- edge flaps. An aeroelastic analysis is used represent the helicopter with trailing-edge flaps. A compressible unsteady aerodynamic model is used to predict the incremental airloads due to trailing-edge flap motion. The material and mechanical hysteresis in the piezoelectric actuator is modeled using the classical Preisach

S. R. Viswamurthy; Ranjan Ganguli

2006-01-01

219

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

220

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

PubMed

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. PMID:18764035

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

2008-07-11

221

Hysteresis characteristics computation on PWM fed synchronous reluctance motor using coupled FEM and Preisach modeling  

Microsoft Academic Search

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. TMS320C31 DSP installed experimental devices are equipped for the propriety of the proposed method of analysis, and then, both computer

Jung Ho Lee; Dong Seok Hyun

2000-01-01

222

From the Cover: Hysteresis drives cell-cycle transitions in Xenopus laevis egg extracts  

Microsoft Academic Search

Cells progressing through the cell cycle must commit irreversibly to mitosis without slipping back to interphase before properly segregating their chromosomes. A mathematical model of cell-cycle progression in cell-free egg extracts from frog predicts that irreversible transitions into and out of mitosis are driven by hysteresis in the molecular control system. Hysteresis refers to toggle-like switching behavior in a dynamical

Wei Sha; Jonathan Moore; Katherine Chen; Antonio D. Lassaletta; Chung-Seon Yi; John J. Tyson; Jill C. Sible

2003-01-01

223

Hysteresis in a light bulb: connecting electricity and thermodynamics with simple experiments and simulations  

Microsoft Academic Search

A method for integrating energy conversion phenomena, nonlinear circuit behaviour and hysteresis into a simple laboratory activity is demonstrated. Current-voltage data for a flashlight bulb driven at various frequencies and amplitudes are measured and simulated. Non-ohmic behaviour and hysteresis are observed experimentally and reproduced numerically with a model that includes the temperature-dependent specific heat capacity and electrical resistivity of the

D A Clauss; R M Ralich; R D Ramsier

2001-01-01

224

Artificial pumping errors in the Kool–Parker scaling model of soil moisture hysteresis  

Microsoft Academic Search

Hysteresis models that eliminate the artificial pumping errors associated with the Kool–Parker (KP) soil moisture hysteresis model, such as the Parker–Lenhard (PL) method, can be computationally demanding in unsaturated transport models since they need to retain the wetting–drying history of the system. The pumping errors in these models need to be eliminated for correct simulation of cyclical systems (e.g. transport

Adrian D. Werner; David A. Lockington

2006-01-01

225

Thermal and Electric Field Hysteresis Effects in Structuraly Disordered Ferroelectric Materials  

Microsoft Academic Search

Thermal and electric field hysteresis effects near the ferroelectric transition were studied by a high resolution calorimetry and dielectric spectroscopy in several solid and soft disordered ferroelectrics such as perovskite relaxors and P(VDF-TrFE)-based ferroelectric polymers, respectively. Significant thermal hysteresis effects were observed in PMN-PT and SBN crystals as well as in P(VDF-TrFE) polymers reminiscent of the supercooling effect in glassy

Z. Kutnjak

2010-01-01

226

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

227

Finite Element Three-Phase Transformer Modeling Taking Into Account a Vector Hysteresis Model  

Microsoft Academic Search

In this work an approach for modeling a transformer core taking into account magnetic hysteresis is presented. For this purpose, the inverse vector Jiles-Atherton hysteresis model is incorporated in a 2D finite element code. This model allows writing naturally the differential reluctivity tensor which can be directly used in the magnetic field equations. A three-phase transformer is modeled. The excitation

Jean V. Leite; Abdelkader Benabou; Nelson Sadowski; Mauricio V. Ferreira da Luz

2009-01-01

228

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

229

Diurnal Hysteresis Between Soil CO2 and Soil Temperature is Controlled by Soil Water Content  

NASA Astrophysics Data System (ADS)

Soil temperature plays an important role in many model representations of soil CO2 production and transport. However, interactions among environmental variables such as temperature and soil moisture may introduce uncertainty into these models. Among the sources of uncertainty in models of soil CO2 production and transport is daily hysteresis between soil CO2 flux and soil temperature. We quantified the degree to which hysteresis between soil [CO2] and soil temperature is controlled by soil water content in a montane conifer forest, and how this nonlinearity impacts estimates of soil CO2 efflux. Based on chamber measurements at our site, a developed Q10 relationship overestimates CO2 flux by 42 g C m-2 (19%) for the entire growing season due to its inability to account for the daily cycle of soil [CO2], the variability of soil moisture, and moisture-dependent diffusive transport of CO2 through the soil column. Only under late- season dry conditions is the Q10 relationship able to predict CO2 flux. We found that at high levels of soil water content, hysteresis imposes organized, daily variability in the relationship between soil [CO2] and soil temperature, and at low levels of soil water content, hysteresis is minimized. Our results demonstrate that diurnal hysteresis between soil [CO2] and soil temperature is due mostly to the balance (or imbalance in wet soils) between production and diffusion. The seasonality in soil moisture controls the transition from an imbalanced system (where diurnal hysteresis is observed) to a balanced system (no diurnal hysteresis observed). The magnitude of hysteresis in the soil [CO2] - soil temperature relationship is an important indicator of the existence of concomitant, yet independent, autotrophic and heterotrophic soil [CO2] processes. As such, the role of soil water content in controlling the relationship between soil [CO2] and soil temperature should be considered when modeling the dynamics of carbon cycling in ecosystems with strong seasonality in soil water content.

McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.; Muth, D. J.; Epstein, H. E.; Welsch, D. L.; Pacific, V. J.; Wraith, J. M.

2007-12-01

230

Phase transformation and hysteresis behavior in Cs 1 ? x Rb x H 2PO 4  

Microsoft Academic Search

A new theory on the origin of hysteresis in first order phase transformations was evaluated for its applicability to the phase transformation behavior in the Cs1?xRbxH2PO4 solid solution system. Specifically, the correlation between ?2, the middle eigenvalue of the transformation matrix describing the cubic-to-monoclinic superprotonic transition, and the transformation hysteresis was examined. The value of ?2 was estimated from a

Mary W. Louie; Mikhail Kislitsyn; Kaushik Bhattacharya; Sossina M. Haile

2010-01-01

231

Theoretical analysis of the dynamic behavior of hysteresis elements in mechanical systems  

Microsoft Academic Search

Many machine elements in common engineering use exhibit the characteristic of “hysteresis springs”. Plain and rolling element bearings that are widely used in motion guidance of machine tools are typical examples. The study of the non-linear dynamics caused by such elements becomes imperative if we wish to achieve accurate control of such machines.This paper outlines the properties of rate-independent hysteresis

F. Albender; W. Symens; J. Swevers; H. Van Brussel

2004-01-01

232

Hysteresis Effect Implicates Calcium Cycling as a Mechanism of Repolarization Alternans  

Microsoft Academic Search

Background—T-wave alternans is due to alternation of membrane repolarization at the cellular level and is a risk factor for sudden cardiac death. Recently, a hysteresis effect has been reported in patients whereby T-wave alternans, once induced by rapid heart rate, persists even when heart rate is subsequently slowed. We hypothesized that alternans hysteresis is an intrinsic property of cardiac myocytes,

Mariah L. Walker; Xiaoping Wan; Glenn E. Kirsch; David S. Rosenbaum

2010-01-01

233

High-Efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation  

Microsoft Academic Search

This paper presents the new scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation. When the terminal voltage Vi of the hysteresis motor running at synchronous speed is continuously increased up to nVi (n>1) and then continuously decreased to Vi, input currents are reduced and output power is increased at the same time. Because of this, the

Tomotsugu Kubota; Takahiro Tamura; Kazumi Kurihara

2009-01-01

234

A novel double hysteresis-band current control for a three-level voltage source inverter  

Microsoft Academic Search

This paper presents a new current control strategy for a high power three-level voltage source inverter (VSI). This control strategy consists on an extension to a three-level topology of the well-known hysteresis-band current control for a conventional two-level VSI. Line current is controlled by means of two hysteresis bands slightly displaced around the reference value. A simple calculation block decides

M. Lafoz; I. J. Iglesias; C. Veganzones; M. Visiers

2000-01-01

235

Purification and composition of a thermal hysteresis producing protein from the milkweed bug, Oncopeltus fasciatus  

Microsoft Academic Search

A protein which produces a thermal hysteresis (a difference between the freezing and melting points) was purified from the hemolymph of the milkweed bug,Oncopeltus fasciatus. The amino acid composition of theOncopeltus thermal hysteresis protein is somewhat different from that of the larvae of the beetle,Tenebrio molitor, which is the only other insect from which such a protein has as yet

Jean L. Patterson; Thomas J. Kelly; John G. Duman

1981-01-01

236

CMOS layout design of the hysteresis McCulloch-Pitts neuron  

Microsoft Academic Search

Digital CMOS layout design of the hysteresis McCulloch-Pitts neuron is presented. Based on simulation results using the hysteresis McCulloch-Pitts binary neuron model, a 6-bit fixed point 2's complement arithmetic was adopted for the calculation of the input U of each neuron. Each neuron needs 204 transistors and requires a 399 lambda x 368 lambda layout area using the MOSIS scalable

T. Kurokawa; K. C. Lee; Y. B. Cho; Y. Takefuji

1990-01-01

237

Rate-dependent hysteresis losses in ensembles of magnetic nanoparticle clusters  

NASA Astrophysics Data System (ADS)

Hysteresis is ubiquitous in magnetic nanoparticle systems and understanding how it emerges from complex interactions and for different time scales is a long-standing issue in magnetism research. Understanding the phenomenon is most important for engineering magnetic nanoparticle structures of well-controlled properties in magnetic recording, hysteresis loss optimization in hyperthermia cancer treatment in biomedicine, or biological and chemical sensing, to name a few examples. In this work we address one of the general questions related to the influence of thermal activation processes on hysteresis loss. Employing large-scale computational modeling based on the master-equation framework we investigate the influence of dipolar interactions on thermal hysteresis loops in ensembles of magnetic nanoparticle chains and clusters. We show that the directional dependence of dipolar interactions results in enhanced or reduced hysteresis loss, depending on the distribution of particles' anisotropy axes and particle chain orientations with respect to the external field. Additional hysteresis loss reduction occurs in case of particle clusters due to possibility of the frustration phenomenon not present for topologically simpler chains.

Hovorka, Ondrej; Evans, Richard; Friedman, Gary; Chantrell, Roy

2012-02-01

238

From the Cover: Hysteresis drives cell-cycle transitions in Xenopus laevis egg extracts  

NASA Astrophysics Data System (ADS)

Cells progressing through the cell cycle must commit irreversibly to mitosis without slipping back to interphase before properly segregating their chromosomes. A mathematical model of cell-cycle progression in cell-free egg extracts from frog predicts that irreversible transitions into and out of mitosis are driven by hysteresis in the molecular control system. Hysteresis refers to toggle-like switching behavior in a dynamical system. In the mathematical model, the toggle switch is created by positive feedback in the phosphorylation reactions controlling the activity of Cdc2, a protein kinase bound to its regulatory subunit, cyclin B. To determine whether hysteresis underlies entry into and exit from mitosis in cell-free egg extracts, we tested three predictions of the Novak-Tyson model. (i) The minimal concentration of cyclin B necessary to drive an interphase extract into mitosis is distinctly higher than the minimal concentration necessary to hold a mitotic extract in mitosis, evidence for hysteresis. (ii) Unreplicated DNA elevates the cyclin threshold for Cdc2 activation, indication that checkpoints operate by enlarging the hysteresis loop. (iii) A dramatic "slowing down" in the rate of Cdc2 activation is detected at concentrations of cyclin B marginally above the activation threshold. All three predictions were validated. These observations confirm hysteresis as the driving force for cell-cycle transitions into and out of mitosis.

Sha, Wei; Moore, Jonathan; Chen, Katherine; Lassaletta, Antonio D.; Yi, Chung-Seon; Tyson, John J.; Sible, Jill C.

2003-02-01

239

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

PubMed

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

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

2010-05-01

240

Long term stability and hysteresis effects in Pt100 sensors used in industry  

NASA Astrophysics Data System (ADS)

A Pt100 sensor is under normal conditions a very accurate and stable sensor for temperature measurements. Two important factors that can have influence on the results are its drift during time and the hysteresis effect at temperature changes. Different types of Pt100 sensors will show varying sensitivity for these effects. This study includes a number of partially supported wire type Pt100 sensors mainly used as reference sensors at different industries and laboratories. For most of the sensors, there is a history of calibration data for several years. By using a dry block calibrator, the hysteresis effects of the sensors are measured in the temperature range 0 °C up to 500 °C, depending on the calibration range of the sensor. The suitability of the method is evaluated by measurements of the stability of the dry-block and the repeatability of hysteresis tests. The evaluation shows that it is possible to measure hysteresis effects above a few mK. The tested Pt100 sensors exhibits hysteresis effects of 20 mK peak-to-peak as most, which is in the same magnitude as the uncertainty of the calibration and also more significant than the annual drift. The best sensors showed a hysteresis of just a few mK.

Ljungblad, S.; Holmsten, M.; Josefson, L.-E.; Klevedal, B.

2013-09-01

241

Intelligence rules of hysteresis in the feedforward trajectory control of piezoelectrically-driven nanostagers  

NASA Astrophysics Data System (ADS)

Piezoelectrically-driven nanostagers have limited performance in a variety of feedforward and feedback positioning applications because of their nonlinear hysteretic response to input voltage. The hysteresis phenomenon is well known for its complex and multi-path behavior. To realize the underlying physics of this phenomenon and to develop an efficient compensation strategy, the intelligence properties of hysteresis with the effects of non-local memories are discussed here. Through performing a set of experiments on a piezoelectrically-driven nanostager with a high resolution capacitive position sensor, it is shown that for the precise prediction of the hysteresis path, certain memory units are required to store the previous hysteresis trajectory data. Based on the experimental observations, a constitutive memory-based mathematical modeling framework is developed and trained for the precise prediction of the hysteresis path for arbitrarily assigned input profiles. Using the inverse hysteresis model, a feedforward control strategy is then developed and implemented on the nanostager to compensate for the ever-present nonlinearity. Experimental results demonstrate that the controller remarkably eliminates the nonlinear effect, if memory units are sufficiently chosen for the inverse model.

Bashash, Saeid; Jalili, Nader

2007-02-01

242

Feedforward hysteresis compensation in trajectory control of piezoelectrically-driven nanostagers  

NASA Astrophysics Data System (ADS)

Complex structural nonlinearities of piezoelectric materials drastically degrade their performance in variety of micro- and nano-positioning applications. From the precision positioning and control perspective, the multi-path time-history dependent hysteresis phenomenon is the most concerned nonlinearity in piezoelectric actuators to be analyzed. To realize the underlying physics of this phenomenon and to develop an efficient compensation strategy, the intelligent properties of hysteresis with the effects of non-local memories are discussed. Through performing a set of experiments on a piezoelectrically-driven nanostager with high resolution capacitive position sensor, it is shown that for the precise prediction of hysteresis path, certain memory units are required to store the previous hysteresis trajectory data. Based on the experimental observations, a constitutive memory-based mathematical modeling framework is developed and trained for the precise prediction of hysteresis path for arbitrarily assigned input profiles. Using the inverse hysteresis model, a feedforward control strategy is then developed and implemented on the nanostager to compensate for the system everpresent nonlinearity. Experimental results demonstrate that the controller remarkably eliminates the nonlinear effect if memory units are sufficiently chosen for the inverse model.

Bashash, Saeid; Jalili, Nader

2006-04-01

243

Hysteresis in YHx films observed with in situ measurements  

NASA Astrophysics Data System (ADS)

Giant hysteretic effects in the YHx hydrogen switchable mirror system are observed between x=1.9 and x=3 in pressure composition isotherms, optical and electrical properties, and mechanical stress. Polycrystalline Y films are studied by simultaneous in situ measurements of electrical resistivity, optical transmittance and x-ray diffractometry. These experiments are linked to optical microscopy of the samples. During hydrogen loading above x=1.9 the films stay in the metallic fcc phase until the optical transmittance reaches its minimum and the electrical resistance curve exhibits a characteristic feature at x=2.1. Upon further loading the system crosses the miscibility gap in which the fcc phase coexists with the hcp phase before hydrogen saturation is reached in the pure hcp phase. While the fcc phase stays at a concentration of x=2.1 in the coexistence region during loading, it remains at a concentration of x=1.9 during unloading. The hysteretic effects observed in optical transmission and electrical resistivity result from the different properties of the low concentration fcc phase YH1.9 and the high concentration fcc phase YH2.1. They can be explained on the basis of the bulk phase diagram if the different stress states during loading and unloading are taken into account. These results contradict earlier interpretations of the hysteresis in thin film YHx, based on nonsimultaneous measurements of the optical and structural properties on different films.

Remhof, A.; Kerssemakers, J. W.; van der Molen, S. J.; Griessen, R.; Kooij, E. S.

2002-02-01

244

On growth rate hysteresis and catastrophic crystal growth  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

245

Hysteresis in X-ray Transient Spectral Transitions  

NASA Astrophysics Data System (ADS)

We present hardness-intensity plots for several soft X-ray transients (the neutron star Aql X-1 and the black hole candidates 1748-288, 1859+226, 2012+381 and 1550-564) from pointed RXTE observations and RXTE All-Sky Monitor Observations. We show that in all cases for which there is good data, the hardness intensity diagrams over the course of the outburst cycle map out a loop, indicating that hysteresis is present and that the state transitions from hard-to-soft occur at a different luminosity than those from soft-to-hard. We show that this observation (1) rules out propeller effects as the sole cause of state transitions in Aql X-1 and (2) implies a common origin for the state transitions in accreting black holes and neutron stars. We discuss the implications for popular models of state transitions, such as the onset of an adiabatic or advection dominated accretion flow. We discuss the similarities between these results and the similar loop in the diagram of X-ray intensity versus radio intensity previously reported in GX 339-4.

Maccarone, Thomas; Coppi, Paolo

2002-04-01

246

Hysteresis in pentacene-based organic thin-film transistors  

NASA Astrophysics Data System (ADS)

Memory effects are commonly seen in organic thin-film transistor (OTFT) characteristics. In the absence of memory effects associated with the gate dielectric, the hysteresis in p-channel pentacene-based OTFTs, as measured in air and under illumination, was found to be dominated by trapped electrons, rather than trapped holes, in the semiconductor. The responsible acceptor type traps have very long lifetime. The immobile, previously stored negative charge requires extra holes to balance it, resulting in early establishment of the channel and extra drain current. This model is unique in that it discusses the majority carrier population influenced by trapped charge opposite in sign to the majority carriers in a simple electrostatic manner, to explain history dependence. The model was supported by drain current transient decay data. This memory effect is ambient and illumination sensitive. We studied the presence or absence of this effect under various ambient and illumination conditions, and found the responsible acceptor type traps mostly extrinsic and their formation reversible. Efforts were taken in the quantitative analysis to exclude the bias stress effect from the memory effect due to the charged acceptors.

Gu, Gong; Kane, Michael G.

2006-09-01

247

Quantifying hysteresis of atrazine desorption from a sandy loam soil.  

PubMed

Batch experiments were carried out to investigate the effects of initial atrazine concentrations and consecutive desorption steps on the desorption characteristics of atrazine from a sandy loam soil. As initial atrazine concentration increased, the average percentage of atrazine desorption on the sandy loam soil ranged gradually from 23.1% to 38.5% after five consecutive desorption steps. The values of the Freundlich capacity parameter, k(des), derived from the initial concentration and time-dependent desorption isotherm were consistently higher than those associated with sorption. The opposite trend was observed only for the values of nonlinear parameter, n(des), from the initial concentration-dependent desorption isotherms. Atrazine hydrolysis to hydroxyatrazine and bound residue formation were mainly responsible for the observed hysteresis in its sorption and desorption isotherms. For the initial concentration-dependent desorption isotherms, as initial atrazine concentration increased, the values of hysteretic coefficients omega and lamda decreased, and eta values increased. However, the relationships between initial atrazine concentration and hysteretic coefficients were not pronounced for omega, eta, or lamda. For the time-dependent desorption isotherms, lamda and eta values increased as the atrazine desorption step proceeded. The correlation between hysteretic coefficient and desorption step was highly significant for lamda (P < 0.0001), but not for eta. PMID:21462711

Deng, Jiancai; Jiang, Xin; Hu, Weiping; Hu, Liuming

2010-01-01

248

Determination of PRT Hysteresis in the Temperature Range from -50 °C to 300 °C  

NASA Astrophysics Data System (ADS)

This paper discusses the contribution of hysteresis to the measurement uncertainty of industrial platinum resistance thermometers (IPRTs). Hysteresis is one of the sources of uncertainty that has so far not been sufficiently researched and documented. The term hysteresis applies to any system that is path dependent; the output depends on the history of the input. In our case, thermal hysteresis results in different resistance values at the same temperature point, depending on whether the temperature was increasing or decreasing. The reason for such behavior is related to the construction of the thermometer (strain due to thermal expansion and contraction) and also to possible moisture inside the encapsulation. In the process of evaluation of the calibration and measurement capabilities (CMCs) of IPRTs within Working Group 8, the Consultative Committee for Thermometry (CCT WG8) concluded that the uncertainty due to hysteresis is not uniformly defined and not always added to the total uncertainty of the resistance thermometer under calibration. In order to estimate the uncertainty contribution due to the hysteresis and compare different procedures, resistance measurements were carried out on a number of IPRTs of different qualities and tolerance classes. The temperature span was between -50 °C and 300 °C, which is the most frequent temperature range in the practical use of IPRTs. The hysteresis was then determined in different ways (change of resistance at the ice point and at the midpoint temperature according to the ASTM International Standard E644 and according to the new version of IEC Standard 60751), and a comparison of results was made.

Žužek, V.; Batagelj, V.; Bojkovski, J.

2010-09-01

249

Bistability and spatial hysteresis in an Nd:GdVO 4 laser with an intracavity twisted-nematic liquid crystal  

Microsoft Academic Search

In this study, optical bistability accompanied by spatial hysteresis was demonstrated in an Nd:GdVO4 laser with an intracavity twisted-nematic liquid crystal. The low branch of power hysteresis mainly has the spatial distribution\\u000a of the fundamental mode as the pump power increases, whereas a four-mode and varying transverse pattern exist in the high\\u000a branch of power hysteresis as the pump power

M.-D. Wei; D.-Y. Huang; C.-C. Hsu; A.-K. Chang; J.-H. Lin

250

Compensation of rate-dependent hysteresis nonlinearities in a magnetostrictive actuator using an inverse Prandtl-Ishlinskii model  

NASA Astrophysics Data System (ADS)

Magnetostrictive actuators invariably exhibit hysteresis nonlinearities that tend to become significant under high rates of inputs, and could cause oscillations and error in the micro-positioning tasks. This study presents a methodology for compensation of hysteresis nonlinearity in a magnetostrictive actuator subject to a wide range of input rates in an open-loop manner. The hysteresis compensation is attained through application of an inverse rate-dependent Prandtl-Ishlinskii model formulated on the basis of the rate-dependent Prandtl-Ishlinskii hysteresis model and laboratory-measured hysteresis properties of the magnetostrictive actuator under inputs at frequencies up to 200 Hz. The effectiveness of the inverse rate-dependent Prandtl-Ishlinskii model compensator for mitigating the major and minor loop hysteresis nonlinearities is demonstrated through simulation results and hardware-in-the-loop laboratory measurements of a magnetostrictive actuator (stroke ±50 ?m) under inputs in the 1-200 Hz frequency range. Both the simulation and experimental results revealed reduction of peak hysteresis from 4.7 to 0.645 ?m, when the proposed inverse rate-dependent model is applied as a feedforward hysteresis compensator, which occurred under excitations at the lowest frequency of 1 Hz. The results suggest that the inverse Prandtl-Ishlinskii model could provide hysteresis compensation under different rates of inputs in a simple and effective manner.

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

2013-02-01

251

Bistability and spatial hysteresis in an Nd:GdVO4 laser with an intracavity twisted-nematic liquid crystal  

NASA Astrophysics Data System (ADS)

In this study, optical bistability accompanied by spatial hysteresis was demonstrated in an Nd:GdVO4 laser with an intracavity twisted-nematic liquid crystal. The low branch of power hysteresis mainly has the spatial distribution of the fundamental mode as the pump power increases, whereas a four-mode and varying transverse pattern exist in the high branch of power hysteresis as the pump power decreases. The result revealed that the power and spatial hysteresis is controlled by the director axis reorientation and the order parameter modification in twisted-nematic liquid crystals, which is determined by the non-uniform transverse distribution of the intracavity laser intensity.

Wei, M.-D.; Huang, D.-Y.; Hsu, C.-C.; Chang, A.-K.; Lin, J.-H.

2011-11-01

252

The role of charge traps in inducing hysteresis: Capacitance-voltage measurements on top gated bilayer graphene  

NASA Astrophysics Data System (ADS)

Understanding the origin of hysteresis in the channel resistance from top gated graphene transistors is important for transistor applications. Capacitance-voltage measurements across the gate oxide on top gated bilayer graphene show hysteresis with a charging and discharging time constant of ~100 ?s. However, the measured capacitance across the graphene channel does not show any hysteresis but shows an abrupt jump at a high channel voltage due to the emergence of an order, indicating that the origin of hysteresis between gate and source is due to charge traps present in the gate oxide and graphene interface.

Kalon, Gopinadhan; Jun Shin, Young; Giang Truong, Viet; Kalitsov, Alan; Yang, Hyunsoo

2011-08-01

253

Conditions necessary for capillary hysteresis in porous media: Tests of grain-size and surface tension influences  

SciTech Connect

Hysteresis in the relation between water saturation and matric potential is generally regarded as a basic aspect of unsaturated porous media. However, the nature of an upper length scale limit for saturation hysteresis has not been previously addressed. Since hysteresis depends on whether or not capillary rise occurs at the grain scale, this criterion was used to predict required combinations of grain size, surface tension, fluid-fluid density differences, and acceleration in monodisperse systems. The Haines number (Ha), composed of the aforementioned variables, is proposed as a dimensionless number useful for separating hysteretic (Ha < 15) versus nonhysteretic (Ha > 15) behavior. Vanishing of hysteresis was predicted to occur for grain sizes greater than 10.4 +- 0.5 mm, for water-air systems under the acceleration of ordinary gravity, based on Miller-Miller scaling and Haines' original model for hysteresis. Disappearance of hysteresis was tested through measurements of drainage and wetting curves of sands and gravels and occurs between grain sizes of 10 and 14 mm (standard conditions). The influence of surface tension was tested through measurements of moisture retention in 7 mm gravel, without and with a surfactant (sodium dodecylbenzenesulfonate (SDBS)). The ordinary water system (Ha = 7) exhibited hysteresis, while the SDBS system (Ha = 18) did not. The experiments completed in this study indicate that hysteresis in moisture retention relations has an upper limit at Ha = 16 +- 2 and show that hysteresis is not a fundamental feature of unsaturated porous media.

Tokunaga, Tetsu K.; Olson, Keith R.; Wan, Jiamin

2004-03-12

254

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

255

Controller Parameter Tuning for Systems with Hysteresis and Its Application to Shape Memory Alloy Actuators  

NASA Astrophysics Data System (ADS)

This paper proposes a simple controller parameter tuning method that can compensate for hysteresis. The proposed method is based on the so-called fictitious reference iterative tuning (FRIT) technique which can easily tune controller parameters such as proportional-integral-derivative gains using a one-shot closed-loop experimental data. In the proposed framework, a simple hysteresis model is introduced to a control system, and its inverse is used as a hysteresis compensator. Since the hysteresis model is characterized with only three parameters, the related computational burden is moderate in the parameter tuning process. Also, the proposed FRIT method needs an only one-shot experiment as in the standard FRIT one, which implies that the feature of FRIT is well-maintained. In the optimization process, the so-called covariance matrix adaptation evolution strategy is used for simultaneously searching hysteresis parameters as well as controller parameters. The proposed FRIT method is applied to an experimental control system that comprises a shape memory alloy actuator, and its effectiveness is verified.

Wakasa, Yuji; Kanagawa, Shinji; Tanaka, Kanya; Nishimura, Yuki

256

Hysteresis losses of magnetic nanoparticle powders in the single domain size range  

NASA Astrophysics Data System (ADS)

Magnetic iron oxide nanoparticle powders were investigated in order to optimise the specific hysteresis losses for biomedical heating applications. Different samples with a mean particle size in the transition range from superparamagnetic to ferromagnetic behaviour (i.e. 10 100 nm) were prepared by two different chemical precipitation routes. Additionally, the influence of milling and annealing on hysteresis losses of the nanoparticles was investigated. Structural investigations of the samples were carried out by X-ray diffraction, measurement of specific surface area, and scanning and transmission electron microscopy. The dependence of hysteresis losses of minor loops on the field amplitude was determined using vibrating sample magnetometry and caloric measurements. For small field amplitudes, a power law was found which changes into saturation at amplitudes well above the coercive field. Maximum hysteresis losses of 6.6 J/kg per cycle were observed for milled powder. For field amplitudes below about 10 kA/m, which are especially interesting for medical and technical applications, hysteresis losses of all investigated powders were at least by one order of magnitude lower than reported for magnetosomes of comparable size.

Dutz, S.; Hergt, R.; Mürbe, J.; Müller, R.; Zeisberger, M.; Andrä, W.; Töpfer, J.; Bellemann, M. E.

2007-01-01

257

Conjugation of type I antifreeze protein to polyallylamine increases thermal hysteresis activity.  

PubMed

Antifreeze proteins (AFPs) are ice binding proteins found in some plants, insects, and Antarctic fish allowing them to survive at subzero temperatures by inhibiting ice crystal growth. The interaction of AFPs with ice crystals results in a difference between the freezing and melting temperatures, termed thermal hysteresis, which is the most common measure of AFP activity. Creating antifreeze protein constructs that reduce the concentration of protein needed to observe thermal hysteresis activities would be beneficial for diverse applications including cold storage of cells or tissues, ice slurries used in refrigeration systems, and food storage. We demonstrate that conjugating multiple type I AFPs to a polyallylamine chain increases thermal hysteresis activity compared to the original protein. The reaction product is approximately twice as active when compared to the same concentration of free proteins, yielding 0.5 °C thermal hysteresis activity at 0.3 mM protein concentration. More impressively, the amount of protein required to achieve a thermal hysteresis of 0.3 °C is about 100 times lower when conjugated to the polymer (3 ?M) compared to free protein (300 ?M). Ice crystal morphologies observed in the presence of the reaction product are comparable to those of the protein used in the conjugation reaction. PMID:21905742

Can, Ozge; Holland, Nolan B

2011-09-27

258

Climate Hysteresis for Planets Orbiting Stars of Different Spectral Type  

NASA Astrophysics Data System (ADS)

Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. We have explored this effect with a hierarchy of models. Results from both one-dimensional (1-D) radiative transfer and energy balance models and a three-dimensional (3-D) general circulation model indicate that terrestrial planets orbiting stars with higher near-UV radiation exhibit a stronger ice-albedo feedback. We found that ice extent is much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G- or M-dwarf star at an equivalent flux distance, assuming fixed CO2 (present atmospheric level on Earth). The surface ice-albedo feedback effect becomes less important at the outer edge of the habitable zone for main-sequence stars, where the maintenance of surface liquid water requires high atmospheric CO2 concentrations. We show that ?3-10 bar of CO2 will entirely mask the climatic effect of ice and snow, leaving the outer limits of the habitable zone unaffected by the spectral dependence of water ice and snow albedo. However, less CO2 is needed to maintain open water for a planet orbiting an M-dwarf star than would be the case for hotter main-sequence stars. Both entrance into and exit out of a snowball state are sensitive to host star spectral energy distribution. Our simulations indicate a smaller climate hysteresis on M-dwarf planets, as measured by the range of instellation that permits multiple stable ice line latitudes. While M-dwarf planets appear less susceptible to snowball episodes than G- or F-dwarf planets over the course of their evolution, any snowball planets that are found orbiting M-dwarf stars may more easily melt out of these states as stellar luminosity increases over time. This effect is due to the lower-albedo ice on M-dwarf planets which, compounded with near-IR absorption by atmospheric gases, reduces the amount of increased stellar insolation, or “instellation”, necessary to melt these planets out of a snowball state.

Shields, Aomawa; Meadows, V.; Bitz, C.; Pierrehumbert, R.; Joshi, M.; Robinson, T.; Planetary Laboratory, Virtual

2013-10-01

259

Scaling Behavior of Barkhausen Avalanches along the Hysteresis loop in Nucleation-Mediated Magnetization Reversal Process  

SciTech Connect

We report the scaling behavior of Barkhausen avalanches for every small field step along the hysteresis loop in CoCrPt alloy film having perpendicular magnetic anisotropy. Individual Barkhausen avalanche is directly observed utilizing a high-resolution soft X-ray microscopy that provides real space images with a spatial resolution of 15 nm. Barkhausen avalanches are found to exhibit power-law scaling behavior at all field steps along the hysteresis loop, despite their different patterns for each field step. Surprisingly, the scaling exponent of the power-law distribution of Barkhausen avalanches is abruptly altered from 1 {+-} 0.04 to 1.47 {+-} 0.03 as the field step is close to the coercive field. The contribution of coupling among adjacent domains to Barkhausen avalanche process affects the sudden change of the scaling behavior observed at the coercivity-field region on the hysteresis loop of CoCrPt alloy film.

Im, Mi-Young; Fischer, Peter; Kim, D.-H.; Shin, S.-C.

2008-10-14

260

Efficient hysteresis loop simulations of nanoparticle assemblies beyond the uniaxial anisotropy  

NASA Astrophysics Data System (ADS)

We propose a modified Stoner-Wohlfarth model combined with the geometrical approach of the coherent rotation of magnetization for simulating the hysteresis loops of an assembly of magnetic nanoparticles. The temperature and the size distribution are taken into account. This combined model enables the computation of hysteresis loops at low temperatures for assemblies of particles having an arbitrary type of anisotropy. The applicability of this model for fitting experimental data is discussed and results are compared to the zero-field-cooled and field-cooled fits. As an application, the hysteresis loops measured on Co clusters embedded in carbon and germanium matrices are fitted revealing unambiguously the presence of a biaxial anisotropy.

Tamion, Alexandre; Bonet, Edgar; Tournus, Florent; Raufast, Cécile; Hillion, Arnaud; Gaier, Oksana; Dupuis, Véronique

2012-04-01

261

Combinatorial search of thermoelastic shape-memory alloys with extremely small hysteresis width.  

PubMed

Reversibility of structural phase transformations has profound technological implications in a wide range of applications from fatigue life in shape-memory alloys (SMAs) to magnetism in multiferroic oxides. The geometric nonlinear theory of martensite universally applicable to all structural transitions has been developed. It predicts the reversibility of the transitions as manifested in the hysteresis behaviour based solely on crystal symmetry and geometric compatibilities between phases. In this article, we report on the verification of the theory using the high-throughput approach. The thin-film composition-spread technique was devised to rapidly map the lattice parameters and the thermal hysteresis of ternary alloy systems. A clear relationship between the hysteresis and the middle eigenvalue of the transformation stretch tensor as predicted by the theory was observed for the first time. We have also identified a new composition region of titanium-rich SMAs with potential for improved control of SMA properties. PMID:16518396

Cui, Jun; Chu, Yong S; Famodu, Olugbenga O; Furuya, Yasubumi; Hattrick-Simpers, Jae; James, Richard D; Ludwig, Alfred; Thienhaus, Sigurd; Wuttig, Manfred; Zhang, Zhiyong; Takeuchi, Ichiro

2006-03-05

262

Small hysteresis nanocarbon-based integrated circuits on flexible and transparent plastic substrate.  

PubMed

We report small hysteresis integrated circuits by introducing monolayer graphene for the electrodes and a single-walled carbon nanotube network for the channel. Small hysteresis of the device originates from a defect-free graphene surface, where hysteresis was modulated by oxidation. This uniquely combined nanocarbon material device with transparent and flexible properties shows remarkable device performance; subthreshold voltage of 220 mV decade(-1), operation voltage of less than 5 V, on/off ratio of approximately 10(4), mobility of 81 cm(2) V(-1) s(-1), transparency of 83.8% including substrate, no significant transconductance changes in 1000 times of bending test, and only 36% resistance decrease at a tensile strain of 50%. Furthermore, because of the nearly Ohmic contact nature between the graphene and carbon nanotubes, this device demonstrated a contact resistance 100 times lower and a mobility 20 times higher, when compared to an Au electrode. PMID:21322606

Yu, Woo Jong; Lee, Si Young; Chae, Sang Hoon; Perello, David; Han, Gang Hee; Yun, Minhee; Lee, Young Hee

2011-02-15

263

Hysteresis between coral reef calcification and the seawater aragonite saturation state  

NASA Astrophysics Data System (ADS)

predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (?a) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus ?a relationship, with peak NEC rates occurring before the ?a peak and relatively steady nighttime NEC in spite of variable ?a. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and ?a. The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical ?a threshold levels required to shift coral reefs from a net calcifying to a net dissolving state.

McMahon, Ashly; Santos, Isaac R.; Cyronak, Tyler; Eyre, Bradley D.

2013-09-01

264

Disorder identification in hysteresis data: recognition analysis of the random-bond-random-field Ising model.  

PubMed

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. PMID:19905664

Ovchinnikov, O S; Jesse, S; Bintacchit, P; Trolier-McKinstry, S; Kalinin, S V

2009-10-09

265

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

266

Effect of compressive stress on hysteresis loss and magnetostriction of grain oriented Si-Fe sheets  

NASA Astrophysics Data System (ADS)

Changes in hysteresis loss and magnetostriction ? due to compressive stress ? are discussed for grain oriented Si-Fe sheets. L and T samples are prepared for each kind of sheets, where the longitudinal direction of the L/T sample is parallel/transverse to the rolling direction of the sheets. Hysteresis loss of all samples increases owing to compressive stress ?, and the increased value is in proportion to ??. The proportional ratio between them varies depending on the conditions of the sample and measuring maximum flux density.

Yamamoto, Ken-Ichi; Yamashiro, Yasumasa

2003-05-01

267

Monte Carlo simulation study of exchange biased hysteresis loops in nanoparticles  

NASA Astrophysics Data System (ADS)

We present the results of Monte Carlo simulations of the magnetic properties of a model for a single nanoparticle consisting in a ferromagnetic core surrounded by an antiferromagnetic shell. The simulations of hysteresis loops after cooling in a magnetic field display exchange bias effects. In order to understand the origin of the loop shifts, we have studied the thermal dependence of the shell and interface magnetizations under field cooling. These results, together with inspection of the snapshots of the configurations attained at low temperature, show the existence of a net magnetization at the interface which is responsible for the bias of the hysteresis loops.

Iglesias, Òscar; Labarta, Amílcar

2006-02-01

268

Hysteresis shift in Fe-filled carbon nanotubes due to ?-Fe  

NASA Astrophysics Data System (ADS)

The phase distribution of high aspect ratio, Fe-filled carbon nanotubes prepared by pyrolyzing a mixture of powered ferrocene and C60 has been determined by means of Mössbauer spectroscopy. Our results for that characterization are closely related to the observation, after field cooling processes, of a hysteresis loop shift and clearly suggest a spatial phase distribution which includes the presence of a ?-Fe/?-Fe interface. The temperature dependence of the hysteresis loop shift is discussed in terms of localized regions at that interface exhibiting uncompensated antiferromagnetism within reduced dimensions.

Prados, C.; Crespo, P.; González, J. M.; Hernando, A.; Marco, J. F.; Gancedo, R.; Grobert, N.; Terrones, M.; Walton, R. M.; Kroto, H. W.

2002-03-01

269

Effect of the distribution of anisotropy constants on hysteresis losses for magnetic hyperthermia applications  

NASA Astrophysics Data System (ADS)

Magnetic hyperthermia using magnetic nanoparticles is a potential remedial therapy for the reduction of cancer and other tumours. The dominant heating mechanism is hysteresis heating. This means that control of the particle size distribution is essential. However, control of the anisotropy dispersion is also required. We have calculated the effect of the anisotropy distribution on the hysteresis heating in magnetic nanoparticles for hyperthermia applications. Where there is a wide distribution of anisotropy constants the heat output is controlled by the distribution of anisotropy constants. This effect is significant in systems such as magnetite particles where shape anisotropy dominates.

Vallejo-Fernandez, G.; O'Grady, K.

2013-09-01

270

Use of magnetic hysteresis properties and electron spin resonance spectroscopy for the identification of volcanic ash: a preliminary study  

Microsoft Academic Search

This initial study investigates the possible use of hysteresis parameters and electron spin resonance (ESR) spectroscopy to identify and correlate volcanic ash. ESR and hysteresis properties are sensitive to characteristics such as the chemical composition, mineralogy, and grain size and shape. These characteristics are determined by the tectonic setting of the volcano and by the magmatic and eruptive history of

Archana Pawse; Suzanne Beske-Diehl; S. A. Marshall

1998-01-01

271

An adaptive hysteresis-band current control technique of a voltage-fed PWM inverter for machine drive system  

Microsoft Academic Search

An adaptive hysteresis-band control method where the band is modulated with the system parameters to maintain the modulation frequency to be nearly constant is described. Although the technique is applicable to general AC motor drives and other types of load, an interior permanent magnet (IPM) synchronous machine load is considered. Systematic analytical expressions of the hysteresis band are derived as

B. K. Bose

1990-01-01

272

A comparison of analytic and bayesian approaches for characterizing thermal hysteresis in cattle using algebraic and geometric distances  

Technology Transfer Automated Retrieval System (TEKTRAN)

A high ambient temperature poses a serious threat to cattle. Above a certain threshold, an animal’s body temperature (Tb) appears to be driven by the hot cyclic air temperature (Ta) and hysteresis occurs. Elliptical hysteresis describes the output of a process in response to a simple harmonic input,...

273

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

274

Hysteresis, Force Oscillations, and Nonequilibrium Effects in the Adhesion of Spherical Nanoparticles to Atomically Smooth Surfaces  

Microsoft Academic Search

Equilibrium and nonequilibrium aspects of particle adsorption on the walls of fluid-filled nanochannels are examined via molecular dynamics simulations. The force on the particle and the free energy of the system are found to depend on the particle's history (hysteresis), in addition to its radial position and the wetting properties of the fluid, even when the particle moves quasistatically. The

German Drazer; Boris Khusid; Joel Koplik; Andreas Acrivos

2005-01-01

275

Scheme for contact angle and its hysteresis in a multiphase lattice Boltzmann method.  

PubMed

In this paper, a scheme for specifying contact angle and its hysteresis is incorporated into a multiphase lattice Boltzmann method. The scheme is validated through investigations of the dynamic behaviors of a droplet sliding along two kinds of walls: a smooth (ideal) wall and a rough or chemically inhomogeneous (nonideal) wall. For an ideal wall, the wettability of solid substrates is able to be prescribed. For a nonideal wall, arbitrary contact angle hysteresis can be obtained through adjusting advancing and receding angles. Significantly different phenomena can be recovered for the two kinds of walls. For instance, a droplet on an inclined ideal wall under gravity is impossible to stay stationary. However, the droplet on a nonideal wall may be pinned due to contact angle hysteresis. The steady interface shapes of the droplet on an inclined nonideal wall under gravity or in a shear flow quantitatively agree well with the previous numerical studies. Besides, the complex motion of a droplet creeping like an inchworm could be simulated. The scheme is found suitable for the study of contact line problems with and without contact angle hysteresis. PMID:23410454

Wang, Lei; Huang, Hai-bo; Lu, Xi-Yun

2013-01-03

276

Rapid switch-like sea ice growth and land ice–sea ice hysteresis  

Microsoft Academic Search

Rapid and extensive growth of sea ice cover was suggested to play a major role in the sea ice switch mechanism for the glacial cycles as well as on shorter millennial scales [Gildor and Tziperman, 2000]. This mechanism also predicts a hysteresis between sea ice and land ice, such that land ice grows when sea ice cover is small and

Roiy Sayag; Eli Tziperman; Michael Ghil

2004-01-01

277

THE FATIGUE RESISTANCE AND HYSTERESIS OF MAN-MADE FIBRE ROPES  

Microsoft Academic Search

Data on the fatigue life of man-made fibre ropes is updated and the various mechanisms of rope fatigue discussed. One of these mechanisms, internal hysteresis heating, is examined a little further. Such internal heating should be unimportant in cycling polyester and nylon ropes at non-resonant periods over 24 seconds and at loads of up to 50% of break. But internal

M. R. Parsey

1983-01-01

278

Comparison of calculated and measured hysteresis loss in multifilamentary superconducting wire  

Microsoft Academic Search

A previously developed theory for a single round filament of type II superconductor is applied to hysteresis losses in multifilamentary composite conductors. The single filament theory was extended for a wider range of time varying field amplitudes. Two contrasting wires were used to test the theory which predicts a universal curve for the loss in all conductors. A very close

M. Ashkin; G. R. Wagner

1986-01-01

279

Evaporation of sessile water droplets: Universal behaviour in presence of contact angle hysteresis  

Microsoft Academic Search

A theory is presented, which describes the diffusion limited evaporation of sessile water droplets in presence of contact angle hysteresis. Theory describes two stages of evaporation process: (I) evaporation with a constant radius of the droplet base; and (II) evaporation with a constant contact angle. During stage (I) the contact angles decreases from static advancing contact angle to static receding

S. Semenov; V. M. Starov; R. G. Rubio; H. Agogo; M. G. Velarde

280

Thermomechanical stress-strain hysteresis of Sn-Bi eutectic solder alloy  

Microsoft Academic Search

This study details a thermomechanical testing technique, used in an on-going program, to measure stress-strain hysteresis of solder joints. The apparatus closely approximates the mechanical conditions solder joints experience in electronics packages subjected to cyclic temperature changes. The test assembly is composed of a small load frame, an insert of differing thermal expansion coefficient, and a solder joint. Strain gages

C. H. Raeder; L. E. Felton

1995-01-01

281

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

PubMed

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

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

2012-08-01

282

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

283

Comparison of adaptive and fixed-band hysteresis current control considering high frequency harmonics  

Microsoft Academic Search

Shunt active power filters (APF) are widely used in power systems to eliminate the current harmonics and to compensate reactive power due to their accurate and fast operation. In this paper the instantaneous power theory is used to extract the harmonic components of system current. Then fixed- band hysteresis current control is explained. Because of fixed- band variable frequency disadvantages,

Hani Vahedi; Yasser Rahmati Kukandeh; Mahsa Ghapandar Kashani; Aliakbar Dankoob; Abdolreza Sheikholeslami

2011-01-01

284

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

285

Can hysteresis explain different labour market operations between Europe and the United States?  

Microsoft Academic Search

This paper offers an analysis of the labour market operation in Europe and the United States during 1970–1985. It appears that the labour market developments in Europe are more characterized by hysteresis than in the United States. Simulation results indicate that the unemployment rate in Europe would have reached the level of that in the United States in 1985 when

J. J. Graafland

1989-01-01

286

Thermally induced multi-loop hysteresis in the photoluminescence of semiconductor polaritons  

Microsoft Academic Search

We show that multi-loop hysteresis, recently observed by Cotta and Matinaga in semiconductor optical cavities in the strong coupling regime [Phys. Rev. B. 76, 073308 (2007)], can be explained as a competition between the externally controlled pumping intensity and the delayed response of the well in delivering heat to the bottom of the base. As the external pump intensity grows,

Ju´lia E. Parreira; Pablo L. Saldanha; M. C. Nemes

2011-01-01

287

A First Analysis of Flow Field Hysteresis in a Pump Impeller  

Microsoft Academic Search

The measured pump pressure discharge characteristic for a high specific speed radial pump (?s= 1.7) reveals distinct discontinuities in part load operation. These pressure discontinuities occur at different threshold volume fluxes when increasing or decreasing the pump discharge and make up a hysteresis loop. The pump impeller characteristic was evaluated experimentally and numerically by taking the difference between the integrated

Kevin A. Kaupert; Peter Holbein; Thomas Staubli

1996-01-01

288

Soil water hysteresis as a cause of delayed yield from unconfined aquifers  

Microsoft Academic Search

Hysteresis in the relation between soil water content and (negative) pressure head of the soil water produces a lag in the release of pore water from a rewetted soil when the pressure heads are lowered (made more negative). For an unconfined aquifer this means that the water table must drop some distance in response to pumping a well before pore

Herman Bouwer

1979-01-01

289

Optical bistability and hysteresis in a colliding pulse mode locked femtosecond dye laser  

Microsoft Academic Search

The observation of optical bistability in a colliding pulse mode locked dye laser is described. Two lasing states can occur, one at 612 nm and with femtosecond pulse formation and the other at 570 nm and with a CW output. An hysteresis loop can be obtained plotting the output power as a function of the pump laser power. Control of

G. R. Jacobovitz; C. H. Brito Cruz; N. P. Mansur; M. A. Scarparo

1986-01-01

290

On Hysteresis Loss as affected by Previous Magnetic History at Liquid Air Temperature  

Microsoft Academic Search

This Paper is concerned with hysteresis loss in iron at atmospheric and liquid air temperatures under three different conditions: (1) after the iron has been carefully demagnetised, (2) after it has been subjected to a large force (previous history) of about 26 C.G.S. units, and (3) whilst it is under the influence of an external constant magnetising force after demagnetisation.

Ernest Wilson; B C Clayton; A E Power

1911-01-01

291

Preliminary capillary hysteresis simulations for fractured rocks -- model development and results of simulations  

SciTech Connect

As part of the code development and modeling work being carried out to characterize the flow in the unsaturated zone at Yucca Mountain, Nevada, capillary hysteresis models simulating the history-dependence of the characteristic curves have been developed. The objective of the work has been both to develop the hysteresis models, as well as to obtain some preliminary estimates of the possible hysteresis effects in the fractured rocks at Yucca Mountain given the limitations of presently available data. Altogether three different models were developed based on work of other investigators reported in the literature. In these three models different principles are used for determining the scanning paths: in model (1) the scanning paths are interpolated from tabulated first-order scanning curves, in model (2) simple interpolation functions are used for scaling the scanning paths from the expressions of the main wetting and main drying curves and in model (3) the scanning paths are determined from expressions derived based on the dependent domain theory of hysteresis.

Niemi, A.; Bodvarsson, G.S.

1991-11-01

292

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

Microsoft Academic Search

CO2 sequestration in coal reservoirs is a promising technology for reducing atmospheric CO2 concentrations. Of the candidates for geological sequestration, the physics of transport and sequestration in coal is the least well understood. Adsorption hysteresis has been observed for pure gas adsorption on some coals. It is manifest as desorption curves where the loading of gas on coal surfaces is

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

2006-01-01

293

There and (Slowly) Back Again: Entropy-Driven Hysteresis in a Model of DNA Overstretching  

PubMed Central

When pulled along its axis, double-stranded DNA elongates abruptly at a force of ?65 pN. Two physical pictures have been developed to describe this overstretched state. The first proposes that strong forces induce a phase transition to a molten state consisting of unhybridized single strands. The second picture introduces an elongated hybridized phase called S-DNA. Little thermodynamic evidence exists to discriminate directly between these competing pictures. Here we show that within a microscopic model of DNA we can distinguish between the dynamics associated with each. In experiment, considerable hysteresis in a cycle of stretching and shortening develops as temperature is increased. Since there are few possible causes of hysteresis in a system whose extent is appreciable in only one dimension, such behavior offers a discriminating test of the two pictures of overstretching. Most experiments are performed upon nicked DNA, permitting the detachment (unpeeling) of strands. We show that the long-wavelength progression of the unpeeled front generates hysteresis, the character of which agrees with experiment only if we assume the existence of S-DNA. We also show that internal melting can generate hysteresis, the degree of which depends upon the nonextensive loop entropy of single-stranded DNA.

Whitelam, Stephen; Pronk, Sander; Geissler, Phillip L.

2008-01-01

294

Hysteresis properties of magnetic spherules and whole rock specimens from some Paleozoic platform carbonate rocks  

Microsoft Academic Search

It is widely established that many Paleozoic carbonate rocks were remagnetized during the late Paleozoic Kiaman reversed superchron. Yet the paleomagnetic recorders of this event have remained elusive. Magnetic spherules have been candidates for this role, because they are probably authigenic. Therefore we have studied the hysteresis properties of individual magnetic spherules from two formations, the remagnetized Onondaga (Devonian, New

Dongwoo Sukand; Susan L. Halgedahl

1996-01-01

295

Monte Carlo simulation study of exchange biased hysteresis loops in nanoparticles  

Microsoft Academic Search

We present the results of Monte Carlo simulations of the magnetic properties of a model for a single nanoparticle consisting in a ferromagnetic core surrounded by an antiferromagnetic shell. The simulations of hysteresis loops after cooling in a magnetic field display exchange bias effects. In order to understand the origin of the loop shifts, we have studied the thermal dependence

Òscar Iglesias; Amílcar Labarta

2006-01-01

296

STATCOM model in EMTP RV using hysteresis current controlled voltage source converter (VSC)  

Microsoft Academic Search

In this paper, a static compensator (STATCOM) model in EMTP RV of a voltage source converter (VSC) is presented. The STATCOM is connected to the end of a transmission line. The DC\\/AC conversion is obtained by using pulse width modulation (PWM) based on a current hysteresis controller. By regulating the reference current, an adjustable current can be injected into the

Yongan Deng; V. K. Sood; L. Lopes

2005-01-01

297

Hysteresis in photoelectric charging of dust particles in a complex plasma  

SciTech Connect

Starting with the basic equations of number and energy balance along with charge neutrality it is shown that the charge on the particle versus irradiance of incident radiation plot in a complex plasma, illuminated by radiation with periodic irradiance displays hysteresis.

Sodha, M. S.; Srivastava, Sweta [Disha Institute of Management and Technology, Satya Vihar, Vidhan Sabha-Chandrakhuri Marg, Mandir Hasaud, Raipur-492101 (India); Mishra, S. K.; Misra, Shikha [Department of Education Building, University of Lucknow, Lucknow 226007 (India)

2010-05-15

298

Relationships between hysteresis measurements and the constituent properties of ceramic matrix composites. 1: Theory  

Microsoft Academic Search

A methodology for assessing constituent properties of ceramic matrix composites (CMCs) from stress\\/strain curves is developed. The procedures demonstrate how the properties of the interface and the misfit strain can be related to the unload\\/reload hysteresis and the permanent strain. The approach is illustrated in companion papers by obtaining experimental measurements on two CMCs. The results demonstrate why differences in

Emmanuel Vagaggini; Jean-Marc Domergue; Anthony G. Evans

1995-01-01

299

Strain and hysteresis by stochastic matrix cracking in ceramic matrix composites  

Microsoft Academic Search

A theory is presented to predict the stress\\/strain relations and unload\\/reload hysteresis behavior during the evolution of multiple matrix cracking in unidirectional fiber reinforced ceramic matrix composites (CMCs). The theory is based on the similarity between multiple matrix cracking and fiber fragmentation in a single fiber composite, and determines the crack and strain evolution as a function of the statistical

B. K. Ahn; W. A. Curtin

1997-01-01

300

Estimate Interface Shear Stress of Woven Ceramic Matrix Composites from Hysteresis Loops  

NASA Astrophysics Data System (ADS)

An approach to estimate the fiber/matrix interface shear stress of woven ceramic matrix composites during fatigue loading has been developed in this paper. Based on the analysis of the microstructure, the woven ceramic matrix composites were divided into four elements of 0o warp yarns, 90o weft yarns, matrix outside of the yarns and the open porosity. When matrix cracking and fiber/matrix interface debonding occur upon first loading to the peak stress, it is assumed that fiber slipping relative to matrix in the interface debonded region of the 0o warp yarns is the mainly reason for the occurrence of the hysteresis loops of woven ceramic matrix composiets during unloading and subsequent reloading. The unloading interface reverse slip length and reloading interface new slip length are determined by the interface slip mechanisms. The hysteresis loops of three different cases have been derived. The hysteresis loss energy for the strain energy lost per volume during corresponding cycle is formulated in terms of the fiber/matrix interface shear stress. By comparing the experimental hysteresis loss energy with the computational values, the fiber/matrix interface shear stress of woven ceramic matrix composites corresponding to different cycles can then be derived. The theoretical results have been compared with experimental data of two different woven ceramic composites.

Li, Longbiao; Song, Yingdong

2013-03-01

301

Hysteresis control of nonlinear single-acting actuators as applied to brake\\/throttle switching  

Microsoft Academic Search

This paper expands upon some of the design techniques of Gerdes and Hedrick (1999) in order to analyze a class of switched nonlinear systems with hysteresis. Physically, this class represents systems in which the input is supplied by two single-acting actuators (one capable of “pushing”, the other of “pulling”), each possessing first-order nonlinear dynamics. The basic control structure proposed involves

J. Christian Gerdes; J. Karl Hedrick

1999-01-01

302

Modulation of the Chopping Frequency in DC Choppers and PWM Inverters Having Current-Hysteresis Controllers  

Microsoft Academic Search

In a dc chopper converter having its load current regulated by a feedback controller of the fixed hysteresis type, the chopping frequency is shown to depend on the square of the counter EMF of the load. In a pulsewidth modulated (PWM) inverter, the counter EMF is modulated at the output frequency, so the chopping frequency is modulated at twice the

William McMurray

1984-01-01

303

Creep-Fatigue Evaluation by Hysteresis Energy in Modified 9Cr-1Mo Steel  

NASA Astrophysics Data System (ADS)

Researchers proposed the methods of creep-fatigue evaluation, such as time fraction rules or ductility exhaustion rules. However, the microstructure change during creep-fatigue should not be directly considered in these methods. The hysteresis energy contributes to the microstructure change before the crack initiation and the crack initiation and propagation. The creep-fatigue has evaluated by the hysteresis energy in modified 9Cr-1Mo steel which is a candidate for structural material in Fast Breeder Reactor (FBR) plant. Creep-fatigue and fatigue tests were carried out at 723-873K in air. The hysteresis energy per hour at the middle of life (Nf / 2, Nf is the number of cycles to failure) has been evaluated. It is clear that the relationship between this parameter and the time to failure can be expressed by the power-law function. The creep-fatigue life can be evaluated based on the hysteresis energy an hour at Nf / 2 using this relation.

Nagae, Yuji; Takaya, Shigeru; Asayama, Tai

304

Pore structure analysis of an SCR catalyst using a new method for interpreting nitrogen sorption hysteresis  

Microsoft Academic Search

Nitrogen sorption hysteresis of a selective catalytic reduction (SCR) catalyst in its “fresh” and “used” form [Catal. Today 56 (2000) 335] was analysed by employing the Corrugated Pore Structure Model (CPSM-nitrogen) reported elsewhere [Ind. Eng. Chem. Res. 39 (2000) 3747 and Ind. Eng. Chem. Res., 39 (2000) 3764]. The BET surface area and intrinsic pore volume, and surface area distributions

C. E. Salmas; G. P. Androutsopoulos

2001-01-01

305

Calculation of the Eddy Current and Hysteresis Losses in Sheathed Cables Inside a Steel Pipe  

Microsoft Academic Search

This paper presents an analytical method for approximating the eddy current and hysteresis losses in a system of multiple sheathed cables placed in any configuration inside a steel pipe. The method is based on the theory of images, which this paper expands to apply to pipes having high magnetic permeability and high electric conductivity at the same time. The method

Wael Moutassem; George J. Anders

2010-01-01

306

Tailoring anisotropic magnetoresistance and giant magnetoresistance hysteresis loops with spin-polarized current injection  

NASA Astrophysics Data System (ADS)

Current pulses were injected into magnetic nanowires. Their effect on the magnetoresistance hysteresis loops was studied for three morphologies: homogeneous Ni wires, copper wires containing five cobalt/copper bilayers, and hybrid structures composed of a homogeneous Ni half wire and a multilayered Co/Cu half wire. The characteristic features of the action of the current on the magnetization are shown and discussed.

Wegrowe, J.-E.; Kelly, D.; Hoffer, X.; Guittienne, Ph.; Ansermet, J.-Ph.

2001-06-01

307

Acoustic effect on stall hysteresis for low Reynolds number laminar flow  

Microsoft Academic Search

An experimental investigation was conducted in the Virginia Tech Stability Wind Tunnel to determine the effect of sound waves on the separated laminar boundary layer of a wing at low Reynolds numbers. Also studied was the effect of Reynolds number on the stall hysteresis behavior of the airfoil at Reynolds numbers between 100,000 and 300,000. It was found that increasing

C. G. Schaefer Jr.

1986-01-01

308

Accurate position control of a flexible arm using a piezoactuator associated with a hysteresis compensator  

NASA Astrophysics Data System (ADS)

In this work, position control of a one-link flexible arm is undertaken by considering the field-dependent hysteresis behavior of a piezoceramic actuator (piezoactuator in short). The proposed arm is controlled by two actuators: a motor mounted at the hub and a piezoceramic bonded to the surface of the flexible link. In the modeling process, two transfer functions: one from the input torque to output hub angle and the other from the input voltage to the output tip deflection are obtained. The hysteretic behavior of the piezoactuator is experimentally identified using the Preisach model, and the first-order descending (FOD) curves are obtained that are required to design a hysteresis compensator. After establishing the overall control block diagram for the position control of the flexible arm, a quantitative feedback theory (QFT) controller is designed by treating parameter variations and external disturbances as uncertainties. Subsequently, a hysteresis compensator that produces additional control input to the piezoactuator is designed to enhance the vibration control performance. An experimental realization of the proposed control scheme is undertaken and the effect of the hysteresis compensator on vibration control of the flexible arm is evaluated in the time domain.

Choi, Seung-Bok; Seong, Min-Sang; Ha, Sung Hoon

2013-04-01

309

Hysteresis correction of tactile sensor response with a generalized Prandtl-Ishlinskii model  

NASA Astrophysics Data System (ADS)

Tactile sensors are basically arrays of force sensors. Most of these force sensors are made of polymers or conductive rubbers to lower the cost, especially in the case of large area low-medium resolution tactile sensors. The price to pay for such decrease in the cost and complexity is a worse performance. Hysteresis and drift are the two main sources of error. This paper presents a method to reduce the error caused by hysteresis. This method is based on the generalized Prandtl- Ishlinskii model that has been applied to characterize hysteresis and saturation nonlinearities in smart actuators. The classical Prandtl-Ishlinskii model is not suitable because the lack of symmetry the output curves from the sensor show. Other alternatives like the Preisach model are too complex to implement, especially taking into account that a tactile sensor provides many data to process. The approximation error depends on several parameters as well as on the envelope functions that are chosen. Different alternatives are explored in the paper. Moreover, the model can also be inverted. This inverted model allows obtaining the force values from the tactile sensor output while reducing the errors caused by hysteresis. Since implementations of tactile sensors usually have the electronics close to the raw sensor, and this hardware is also commonly based on a microcontroller or even on a FPGA, it is possible to add the algorithms presented in this paper to the set of compensation and calibration procedures to run in the smart sensor.

Sánchez-Durán, José A.; Oballe-Peinado, Óscar; Castellanos-Ramos, Julián; Vidal-Verdú, Fernando

2011-05-01

310

A phase-field study on the hysteresis behaviors and domain patterns of nanocrystalline ferroelectric polycrystals  

NASA Astrophysics Data System (ADS)

The overall hysteresis behavior of nanocrystalline ferroelectric polycrystals demonstrates unique characteristics against conventional ferroelectric ceramics. The existence of low-permittivity paraelectric grain boundary and its influence to the microstructure of grains can be a key factor leading to such characteristics, especially the grain size-dependent properties. A two dimensional (2D) polycrystalline phase-field model, which distinguishes the grain boundary from the ferroelectric grain, has been developed to investigate the microstructural evolution and hysteresis behavior of nanocrystalline barium titanate (BaTiO3) polycrystals. The results show apparent grain-size dependence on the hysteresis and noticeable vortex polarization structure that dominates the grains as the grain size reduces to tens of nanometers. By studying the hysteresis and domain patterns, it is observed that the grain size-dependent properties are significantly attributed to the grain boundary in two ways: the ``dilution effect'' due to its low permittivity and paraelectric property that are intensified with increased volume concentration, and the extrinsic effect due to the existence of depolarization field, leading to the superparaelectric domain structure. We conclude that this grain-size dependent microstructural mechanism can well explain various experimentally observed properties of nano-grained ferroelectric polycrystals.

Liu, Ning; Su, Yu; Weng, George J.

2013-05-01

311

Application of a Soil Water Hysteresis Model to Simple Water Retention Curves  

Microsoft Academic Search

The Parlange hysteresis model is reformulated as a pair of recurrence relations to provide relationships between wetting and drying phases to any order. The model is applied to the classical van Genuchten model for soil water retention used as the main wetting curve. The nonphysical behaviour of these retention curves is related to the existence of a point of inflection

R. D. Braddock; J.-Y. Parlange; H. Lee

2001-01-01

312

Hysteresis Studies of 7075 Material Test Performed by Schijve and Jacobs.  

National Technical Information Service (NTIS)

The Hysteresis fatigue Analysis (HFA) method uses a cyclic stress- strain curve in conjunction with a Neuber analyses to describe a notch stress- strain history. The notch stresses are then used in a damage theory which employs an equivalent stress. The H...

D. Hayes B. Duncan

1974-01-01

313

Calculation of hysteresis losses in hard superconductors carrying ac: isolated conductors and edges of thin sheets  

Microsoft Academic Search

Two methods of calculating hysteresis losses in hard superconductors are described. The London model is assumed in which the critical current density is taken independent of magnetic field. Losses in isolated wires of different cross section are considered but it is found that losses for solid wires vary by at most a factor of 3 for different shaped wires of

W T Norris

1970-01-01

314

Experimental investigation on hysteresis effect of refrigerant flowing through a coiled adiabatic capillary tube  

Microsoft Academic Search

This paper experimentally investigates the mass flow rate hysteresis of R22 in a coiled adiabatic capillary tube. The measured mass flow rate data in a coiled adiabatic capillary are found to be more dispersive than those in a straight one. The scatter bands of measured data are significantly dependent on how the state points are achieved. For increasing inlet subcooling

Zhou Guobing; Zhang Yufeng

2006-01-01

315

[Mathematical models of hysteresis]. Progress report No. 4, [January 1, 1991--December 31, 1991  

SciTech Connect

The research described in this proposal is currently being supported by the US Department of Energy under the contract ``Mathematical Models of Hysteresis``. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with ``nonlocal memories``. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

Mayergoyz, I.D.

1991-12-31

316

Transient hysteresis of near-surface permafrost response to external forcing  

NASA Astrophysics Data System (ADS)

Estimates of changes in near-surface permafrost (NSP) area S p relative to change in globally averaged surface air temperature T g are made by using the global climate model developed at the A.M. Obukhov Institute of Atmospheric Physics RAS (IAP RAS CM). For ensemble of runs forced by scenarios constructed as return-to-preindustrial continuations of the RCP (Representative Concentration Pathways) scenarios family, a possibility of transient hysteresis in dependence of S p versus T g is exhibited: in some temperature range which depends on imposed scenario of external forcing, NSP area is larger, at the same global mean surface air temperature, in a warming climate than in a cooling climate. This hysteresis is visible more clearly for scenarios with higher concentration of greenhouse gases in the atmosphere in comparison to those in which this concentration is lower. Hysteresis details are not sensitive to the type of the prescribed continuation path which is used to return the climate to the preindustrial state. The multiple-valued dependence of S p on T g arises due to dependence of soil state in the regions of extra-tropical wetlands and near the contemporary NSP boundaries on sign of external climatic forcing. To study the dependence of permafrost hysteresis on amplitude and temporal scale of external forcing, additional model runs are performed. These runs are forced by idealised scenarios of atmospheric CO2 content varying, depending on run, with periods from 100 to 1,000 year and with different amplitudes. It is shown that the above-mentioned hysteresis is related to the impact of phase transitions of soil water on apparent inertia of the system as well as to the impact of soil state on atmospheric hydrological cycle and radiation transfer in the atmosphere.

Eliseev, Alexey V.; Demchenko, Pavel F.; Arzhanov, Maxim M.; Mokhov, Igor I.

2013-01-01

317

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

318

Simulation of polarization, energy storage, and hysteresis in composite dielectrics containing nonlinear inclusions  

NASA Astrophysics Data System (ADS)

Finite difference quasi-electrostatic modeling is used to predict the dielectric behavior of composites consisting of spherical inclusions having nonlinear dielectric polarization behavior that are dispersed in a background linear dielectric matrix. The inclusion nonlinearities are parameterized by a hyperbolic tangent model that includes hysteresis. Computations of composite polarization and energy storage versus applied field and inclusion filling fraction are presented for ordered and random geometries. Electric field statistics are investigated with regard to localized intensification in the matrix, which is relevant to breakdown, and with regard to remnant fields in the inclusions, which is associated with hysteresis. Inclusion saturation behavior is found to cause dramatic departures from the predictions of linear theory, resulting in reduced energy storage in the composites and the existence of optimum filling fractions. Considering various competing factors, an energy storage of 10-12 J/cm3 at applied fields of 300-350 V/?m could be feasible in a composite composed of a linear matrix with a dielectric constant of 12 containing volumetric filling fraction 0.3-0.4 of inclusions with a low field dielectric constant of 1200 and a saturation polarization of 0.15 Cm-2. In spite of significant inclusion hysteresis, the composites displayed only minor overall hysteresis behavior, with > 94% recoverable energy being typical, provided the filling fraction was below percolation. With sufficiently high inclusion hysteresis, a bimodal distribution in the polarizations and fields within the inclusions appeared during downswing, manifesting itself as spontaneously organized regions of oppositely aligned polarization that resemble domains.

Calame, J. P.

2011-09-01

319

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

320

A time-dependent stop operator for modeling a class of singular hysteresis loops in a piezoceramic actuator  

NASA Astrophysics Data System (ADS)

We present a time-dependent stop operator-based Prandtl–Ishlinskii model to characterize singular hysteresis loops in a piezoceramic actuator. The model is constructed based on the time-dependent threshold. The inverse time-dependent stop operator-based Prandtl–Ishlinskii model is obtained analytically and it can be applied as a feedforward compensator to compensate for singular hysteresis loops in a class of smart-material-based actuators. The objective of this study is to present an invertible Prandtl–Ishlinskii model that can be applied as a feedforward compensator to compensate for singular hysteresis loops without inserting a feedback control system.

Al Janaideh, Mohammad

2013-03-01

321

Hysteresis in the conductance of asymmetrically biased GaAs quantum point contacts with in-plane side gates  

NASA Astrophysics Data System (ADS)

We have observed hysteresis between the forward and reverse sweeps of a common mode bias applied to the two in-plane side gates of an asymmetrically biased GaAs quantum point contact (QPC). The size of the hysteresis loop increases with the amount of bias asymmetry ?Vg between the two side gates and depends on the polarity of ?Vg. Our results are in qualitative agreement with Non-Equilibrium Green's Function simulations including the effects of dangling bond scattering on the sidewalls of the QPC. It is argued that hysteresis may constitute another indirect proof of spontaneous spin polarization in the narrow portion of the QPC.

Bhandari, N.; Dutta, M.; Charles, J.; Cahay, M.; Newrock, R. S.

2013-07-01

322

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

323

Hysteresis variations of (Pb, La)(Zr, Ti)O3 capacitors baked in a hydrogen atmosphere  

NASA Astrophysics Data System (ADS)

Baking (Pb, La)(Zr, Ti)O3 capacitors in a hydrogen atmosphere causes a significant loss of remanent polarization even at 150 °C. The hysteresis variations depend on the polarization states during baking. The hysteresis loop showed voltage shifts when the capacitor was polarized before baking, whereas it became a cramped shape when the baking was carried out on a virgin capacitor. Although remanent polarization diminished in all cases, saturation polarization was not suppressed. The clamped hysteresis loop can be described as an average of two loops shifted to positive and negative voltages. The results indicate that the loss of remanent polarization is not due to the suppression of switching, but due to the shift of the hysteresis of each domain larger than the coercive voltage.

Tamura, T.; Matsuura, K.; Ashida, H.; Kondo, K.; Otani, S.

1999-05-01

324

Hysteresis mechanism in low-voltage and high mobility pentacene thin-film transistors with polyvinyl alcohol dielectric  

NASA Astrophysics Data System (ADS)

In this letter, the hysteresis mechanism of organic thin-film transistors (OTFTs) with polyvinyl alcohol (PVA) as gate dielectric is studied. By examining OTFTs with a blocking polymer layer between gate and PVA or between channel and PVA, we confirm that the origin of the hysteresis is caused by the holes injected from the gate and/or from the channel and trapped in the interface of pentacene/PVA and the PVA bulk. A method is proposed to reduce the hysteresis. As a result, a pentacene OTFT with free-hysteresis and high mobility of 1.8 cm2/Vs is achieved by a triple-layer polymer dielectric at low-operating voltages.

Wang, Wei; Ma, Dongge; Pan, Su; Yang, Yudan

2012-07-01

325

Perfluoropolyether-infused nano-texture: a versatile approach to omniphobic coatings with low hysteresis and high transparency.  

PubMed

By infusing a perfluoropolyether lubricating liquid into a nano-textured alumina gel film that was modified with perfluoroalkylphosphonic acid, an omniphobic coating with low hysteresis for both polar and non-polar liquids was prepared. PMID:23211832

Ma, Wei; Higaki, Yuji; Otsuka, Hideyuki; Takahara, Atsushi

2012-12-04

326

Hysteresis Rules and Design Parameter Assessment of RC Low-Rise Shear Walls and Buildings with Openings.  

National Technical Information Service (NTIS)

The objective of this research project is to investigate the inelastic behavior and hysteresis rules of lowrise RC perforated shear walls through experimental and analytical studies based on various types of monotonic and earthquake loads. Results derived...

F. Y. Cheng J. S. Yang

1996-01-01

327

Magnetic Study of Martensitic Transformation in Austenitic Stainless Steel by Low Field Hysteresis Loops Analysis  

SciTech Connect

Magnetic method has been used to evaluate the volume percentage of {alpha}' martensitic phase in austenitic stainless steels by measuring saturation magnetization, and it is said to be a candidate NDE method. However, nondestructive detection of saturation magnetization without high magnetic field is difficult. In the current work, we present a NDE method for evaluating the magnetic properties of strain induced {alpha}' martensitic phase. Low field hysteresis loops of an austenitic stainless steels type SUS 304 after cold rolling were measured by using a yoke sensor. The results show that the initial permeability {mu}i and the relative coercive field Hcl calculated by low field hysteresis loop analysis keep monotonic relation with saturation magnetization and coercive force measured by VSM, respectively. By this method, it is possible to characterize the volume content and particle properties of {alpha}' martensitic phase in stainless steels.

Zhang Lefu; Takahashi, Seiki; Kamada, Yasuhiro; Kikuchi, Hiroaki; Mumtaz, Khalid; Ara, Katsuyuki; Sato, Masaya [NDE Center, Faculty of Engineering, Iwate University, Morioka, 020-8551 (Japan)

2005-04-09

328

Magnon supersolid and anomalous hysteresis in spin dimers on a triangular lattice  

NASA Astrophysics Data System (ADS)

We study the magnetic phase diagram and hysteresis behavior of weakly coupled spin dimers on a triangular lattice using the cluster mean-field method with cluster-size scaling. We find that the magnetization curve has plateaus at 1/3 and 2/3 of the total magnetization, in which local singlet and triplet states form a superlattice pattern. Moreover, if increasing (decreasing) the magnetic field from the 1/3 (2/3) plateau, the Bose-Einstein condensation (BEC) of triplons occurs on the superlattice background, leading to the transition into “magnon supersolid” phase. We also find that the first-order transition between these solid states and the standard magnon BEC state exhibits an anomalous hysteresis upon cycling the magnetic field; the transition can occur only from solid to BEC, and the system cannot return to the initial solid state in the reverse process.

Yamamoto, Daisuke; Danshita, Ippei

2013-07-01

329

Data-driven techniques to estimate parameters in a rate-dependent ferromagnetic hysteresis model  

NASA Astrophysics Data System (ADS)

The quantification of rate-dependent ferromagnetic hysteresis is important in a range of applications including high speed milling using Terfenol-D actuators. There exist a variety of frameworks for characterizing rate-dependent hysteresis including the magnetic model in Ref. [2], the homogenized energy framework, Preisach formulations that accommodate after-effects, and Prandtl-Ishlinskii models. A critical issue when using any of these models to characterize physical devices concerns the efficient estimation of model parameters through least squares data fits. A crux of this issue is the determination of initial parameter estimates based on easily measured attributes of the data. In this paper, we present data-driven techniques to efficiently and robustly estimate parameters in the homogenized energy model. This framework was chosen due to its physical basis and its applicability to ferroelectric, ferromagnetic and ferroelastic materials.

Hu, Zhengzheng; Smith, Ralph C.; Ernstberger, Jon M.

2012-05-01

330

Nonhysteretic behavior inside the hysteresis loop of VO2 and its possible application in infrared imaging  

NASA Astrophysics Data System (ADS)

In the resistive phase transition in VO2, temperature excursions taken from points on the major hysteresis loop produce minor loops. For sufficiently small excursions these minor loops degenerate into single-valued, nonhysteretic branches (NHBs) linear in log(?) versus T and having essentially the same or even higher temperature coefficient of resistance (TCR) as the semiconducting phase at room temperature. We explain this behavior based on the microscopic picture of percolating phases. Similar short NHBs are found in otherwise hysteretic optical reflectivity. We discuss the opportunities NHBs present for infrared imaging technology based on resistive microbolometers. It is possible to choose a NHB with 102-103 times smaller resistivity than in a pure semiconducting phase, thus providing a microbolometer operating without hysteresis, with low tunable resistivity, and high TCR. Unique features of the proposed method and projected figures of merit are discussed in the context of uncooled focal plane array IR visualization technology.

Gurvitch, M.; Luryi, S.; Polyakov, A.; Shabalov, A.

2009-11-01

331

Re-examination of the Steinmetz law for unsymmetrical magnetic hysteresis loops  

NASA Astrophysics Data System (ADS)

We have re-examined the Steinmetz law for unsymmetrical flux-density(B)-field(H) loops in an arbitrary magnetized state for cold rolled steels from the viewpoint of magnetization mechanism. Under the criterion of B-H loops with |B|<˜ 1.1 T, a relation between the hysteresis loss and flux density change was found to fall almost the same curve as that for symmetrical loops obtained conventionally. In the intermediate B regime, the relation follows the usual Steinmetz law with a power-law exponent of 1.6, whose coefficient increases with defect density. These observations demonstrate that the hysteresis loss is only the function of the flux density change and the Steinmetz law always holds true in an arbitrary magnetized state if the pinning mechanism of irreversible Bloch wall motion prevails.

Kobayashi, Satoru; Ishibashi, Yusuke; Baba, Ryo

2013-03-01

332

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

333

Annual variability in a conceptual climate model: snapshot attractors, hysteresis in extreme events, and climate sensitivity.  

PubMed

In a conceptual model of global atmospheric circulation, the effects of annually periodic driving are investigated. The driven system is represented in terms of snapshot attractors, which may remain fractal at all times. This is due to the transiently chaotic behavior in the regular parameter regimes of the undriven system. The driving with annual periodicity is found to be relatively fast: There is a considerable deviation from the undriven case. Accordingly, the existence of a hysteresis loop is identified, namely, the extremal values of a given variable depend not only on the actual strength of the insolation but also on the sign of its temporal change. This hysteresis is due to a kind of internal memory. In the threshold-dependence of mean return times of various extreme events, a roughly exponential scaling is found. Climate sensitivity parameters are defined, and the measure of certain types of extremal behavior is found to be strongly susceptible to changes in insolation. PMID:22757517

Bódai, Tamás; Tél, Tamás

2012-06-01

334

Thermally induced multi-loop hysteresis in the photoluminescence of semiconductor polaritons  

NASA Astrophysics Data System (ADS)

We show that multi-loop hysteresis, recently observed by Cotta and Matinaga in semiconductor optical cavities in the strong coupling regime [Phys. Rev. B. 76, 073308 (2007)], can be explained as a competition between the externally controlled pumping intensity and the delayed response of the well in delivering heat to the bottom of the base. As the external pump intensity grows, the material heats proportionally. However, when the pump intensity decreases, the system cannot deliver heat to the cooled base at the same rate, and the temperature decreases with a delay in relation to the pump intensity. This time mismatch is responsible for the hysteresis and the crossing of the curves. We also show how this type of experiment can be used to clarify the complicated process of thermal dynamics in semiconductors.

Parreira, Júlia E.; Saldanha, Pablo L.; Nemes, M. C.

2011-07-01

335

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

336

Sweep rate dependence of magnetic hysteresis loops and peak effect in high-? superconductors  

NASA Astrophysics Data System (ADS)

The origin of the peak effect in QMG-processed YBCO was investigated using the sweep rate dependence of magnetic hysteresis loops. A numerical analysis of magnetic hysteresis loops demonstrated that electric field E versus current density J characteristics can be accurately derived from the sweep rate dependence using the Mawatari method rather than the conventional Bean one. The pinning potential energy can be obtained from the slope of the log E versus log J plot accurately. By analysing the experimental data with the peak effect using the Mawatari method, it was found that the pinning potential energy and the critical current density have the peak values at different magnetic fields. This anomalous phenomenon incidental to the peak effect can be explained by the Klein model which is based on the concept of the field-induced flux pinning.

Sueyoshi, T.; Fujiyoshi, T.; Miyahara, K.; Awaji, S.

1999-02-01

337

Neurons with hysteresis form a network that can learn without any changes in synaptic connection strengths  

NASA Astrophysics Data System (ADS)

A neural network concept derived from an analogy between the immune system and the central nerous system is outlined. The theory is based on a nervous that is slightly more complicated than the conventional McCullogh-Pitts type of neuron, in that it exhibits hysteresis at the single cell level. This added complication is compensated by the fact that a network of such neurons is able to learn without the necessity for any changes in synaptic connection strengths. The learning occurs as a natural consequence of interactions between the network and its enviornment, with environmental stimuli moving the system around in an N-dimensional phase space, until a point in phase space is reached such that the system's responses are appropriate for dealing with the stimuli. Due to the hysteresis associated with each neuron, the system tends to stay in the region of phase space where it is located. The theory includes a role for sleep in learning.

Hoffmann, Geoffrey W.; Benson, Maurice W.

1986-08-01

338

Focal length hysteresis of a double-liquid lens based on electrowetting  

NASA Astrophysics Data System (ADS)

In this paper, an extended Young equation especially suited for an ideal cylindrical double-liquid variable-focus lens is derived by means of an energy minimization method. Based on the extended Young equation, a kind of focal length hysteresis effect is introduced into the double-liquid variable-focus lens. Such an effect can be explained theoretically by adding a force of friction to the tri-phase contact line. Theoretical analysis shows that the focal length at a particular voltage can be different depending on whether the applied voltage is increasing or decreasing, that is, there is a focal length hysteresis effect. Moreover, the focal length at a particular voltage must be larger when the voltage is rising than when it is dropping. These conclusions are also verified by experiments.

Peng, Runling; Wang, Dazhen; Hu, Zhiwei; Chen, Jiabi; Zhuang, Songlin

2013-02-01

339

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

340

Stress-induced magnetic hysteresis in amorphous microwires probed by microwave giant magnetoimpedance measurements  

NASA Astrophysics Data System (ADS)

We report the results of a detailed study of the effects of tensile and torsional stresses on the giant magnetoimpedance (GMI) characteristics of vanishing-magnetostrictive Co-rich microwires at microwave frequency. A complex stress-induced hysteresis behaviour is identified in the GMI response in the presence of tensile and torsional stresses. It is also revealed that there exists a competition between these two kinds of stresses on the critical field via the interactions with the intrinsic anisotropy. An ``enhanced core-shell'' model is proposed here to resolve the physical origin of the low-field hysteresis and the dependence of induced anisotropy field on the applied tensile and/or torsional stress. Our results are of both technical importance to the design of non-contact stress sensors exploiting the GMI of microwires and fundamental significance to the understanding of the microwave GMI characteristics of soft magnetic microwires in the presence of external stresses.

Popov, V. V.; Berzhansky, V. N.; Gomonay, H. V.; Qin, F. X.

2013-05-01

341

Hysteresis phenomenon in the dynamics of spiral waves rotating around a hole  

NASA Astrophysics Data System (ADS)

Hysteresis in the pinning-depinning transitions of spiral waves rotating around a hole in a circular shaped two-dimensional excitable medium is studied both by use of the continuation software AUTO and by direct numerical integration of the reaction-diffusion equations for the FitzHugh-Nagumo model. In order to clarify the role of different factors in this phenomenon, a kinematical description is applied. It is found that the hysteresis phenomenon computed for the reaction-diffusion model can be reproduced qualitatively only when a nonlinear eikonal equation (i.e. velocity-curvature relationship) is assumed. However, to obtain quantitative agreement, the dispersion relation has to be taken into account.

Zykov, V.; Bordyugov, G.; Lentz, H.; Engel, H.

2010-06-01

342

Strong hysteresis near solidification points of alkali halides with high ionic-radii ratios  

NASA Astrophysics Data System (ADS)

A series of conductance measurements of alkali halides NaCl, NaBr, and NaI was performed in a range of 600-1100 K including liquid and solid states for both cooling and heating regimes. The hysteresis phenomenon is observed to be more pronounced for salts with higher ionic-radii ratio (200 K for NaI) with relaxation time exceeding hundreds of hours. At the cooling regime the conductivity drops slowly from a high value typical for liquids at the freezing point to a solid-salt value defined by a Na+ migration energy at the end of the hysteresis interval instead of an abrupt jump expected at the usual first-order transition. A sort of glassification is assumed to be present at the solidification interval of the salts with high ionic-radii ratios.

Voronel, A.; Shasha, E.; Linsky, D.; Feldberg, S.

1993-07-01

343

Acoustic effect on stall hysteresis for low Reynolds number laminar flow  

NASA Astrophysics Data System (ADS)

An experimental investigation was conducted in the Virginia Tech Stability Wind Tunnel to determine the effect of sound waves on the separated laminar boundary layer of a wing at low Reynolds numbers. Also studied was the effect of Reynolds number on the stall hysteresis behavior of the airfoil at Reynolds numbers between 100,000 and 300,000. It was found that increasing the Reynolds number changed the location and magnitude of the maximum lift coefficient. The stall hysteresis loop, a phenomenon that occurs only at low Re, in which the alpha at flow separation and that at reattachment are not identical, was also found to change with increasing Reynolds numbers. It was found that sound could be used to excite turbulence in a separated laminar boundary layer and cause flow reattachment via a laminar bubble. The required sound frequency and level were found to vary with Reynolds number and angle of attack.

Schaefer, C. G., Jr.

344

A thermodynamic consistent material model for hysteresis effects in ferroelectric ceramics and its finite element implementation  

NASA Astrophysics Data System (ADS)

This paper is concerned with a macroscopic constitutive law for domain switching effects, which occur in piezoelectric ceramics. The thermodynamical framework of the law is based on two scalar valued functions: the electric free Gibbs energy and a switching surface. In common usage, the remanent polarization and the remanent strain are employed as internal variables. The novel aspect of the present work is to introduce an irreversible electric field, which serves besides the irreversible strain as internal variable. The irreversible electric field has only theoretical meaning, but it makes the formulation very suitable for a finite element implementation, where displacements and the electric potential are the nodal degrees of freedom. The constitutive model reproduces the ferroelastic and the ferroelectric hysteresis as well as the butterfly hysteresis and it accounts for the mechanical depolarization effect.

Klinkel, Sven; Wagner, Werner

2007-04-01

345

Force control of a magnetorheological damper using an elementary hysteresis model-based feedforward neural network  

NASA Astrophysics Data System (ADS)

An inverse controller is proposed for a magnetorheological (MR) damper that consists of a hysteresis model and a voltage controller. The force characteristics of the MR damper caused by excitation signals are represented by a feedforward neural network (FNN) with an elementary hysteresis model (EHM). The voltage controller is constructed using another FNN to calculate a suitable input signal that will allow the MR damper to produce the desired damping force. The performance of the proposed EHM-based FNN controller is experimentally compared to existing control methodologies, such as clipped-optimal control, signum function control, conventional FNN, and recurrent neural network with displacement or velocity inputs. The results show that the proposed controller, which does not require force feedback to implement, provides excellent accuracy, fast response time, and lower energy consumption.

Ekkachai, Kittipong; Tungpimolrut, Kanokvate; Nilkhamhang, Itthisek

2013-11-01

346

Polarization-dependent asymmetric hysteresis behavior in ZnCrO layers  

NASA Astrophysics Data System (ADS)

A ZnCrO layer grown on a Pt (111)/Al2O3 (0001) substrate exhibits a lattice displacement-induced ferroelectric behavior due to a modulation in the lattice translation symmetry. The top-to-bottom Pt/ZnCrO/Pt structure shows asymmetric hysteresis loops in positive and negative voltage bias regions. This is attributed to a change in the Schottky emission rate due to the nonlinear polarization of the ZnCrO barrier. The characteristics of the hysteresis loops depend on the film-textures of ZnCrO, which vary with the oxygen partial pressure during the growth stage of the ZnCrO layers. The results suggest that ZnCrO has efficacy characteristics for applications in the non-volatile resistive-switching systems.

Lee, Youngmin; Kim, Deuk Young; Lee, Sejoon; Fu, Dejun

2012-06-01

347

Simulation of polarization and butterfly hysteresis loops in bismuth layer-structured ferroelectric thin films  

NASA Astrophysics Data System (ADS)

Modeling of the hysteresis loop of ferroelectric thin films has been thought very difficult owing to its nonlinear and history-dependent electric field effects. Here we extend the Preisach model [Z. Phys. 94, 277 (1935)] by using the distribution function integral and superposition method. The model shows improved hysteresis loop that agrees reasonably well with the experimental data measured from the bismuth layer-structured ferroelectric thin films. Compared with the previous model, the current model provides polarization-field (P-E) loop with full and symmetric shape, suitable coercive field (Ec), and few undesirable parameters. The butterfly loop of perovskite-type ferroelectric thin films is also simulated. Additionally, the approach is able to describe the unsaturated loops obtained under various ac electric fields, which is very useful in circuit simulation of ferroelectric field effect transistor or ferroelectric capacitor.

Ye, Z.; Tang, M. H.; Cheng, C. P.; Zhou, Y. C.; Zheng, X. J.; Hu, Z. S.

2006-11-01

348

Dynamical hysteresis and spatial synchronization in coupled non-identical chaotic oscillators  

NASA Astrophysics Data System (ADS)

We identify a novel phenomenon in distinct (namely non-identical) coupled chaotic systems, which we term dynamical hysteresis. This behavior, which appears to be universal, is defined in terms of the system dynamics (quantified for example through the Lyapunov exponents), and arises from the presence of at least two coexisting stable attractors over a finite range of coupling, with a change of stability outside this range. Further characterization via mutual synchronization indices reveals that one attractor corresponds to spatially synchronized oscillators, while the other corresponds to desynchronized oscillators. Dynamical hysteresis may thus help to understand critical aspects of the dynamical behavior of complex biological systems, e.g. seizures in the epileptic brain can be viewed as transitions between different dynamical phases caused by time dependence in the brain's internal coupling.

Prasad, Awadhesh; Iasemidis, Leon D.; Sabesan, Shivkumar; Tsakalis, Kostas

2005-04-01

349

Enhancement of the magnetic hysteresis in ultrathin PdNi films by hydrogen absorption-desorption cycling  

NASA Astrophysics Data System (ADS)

Measurements of the magnetic hysteresis in ultrathin PdNi films (d <~ 100 Å) show a marked increase of the perpendicular coercitive field after hydrogen absorption-desorption cycling; a squaring up of the magnetic hysteresis is observed at the same time. We attribute temtatively this effect to an irreversible change of the stress state of the film in relation with the film-substrate interaction.

Raffy, H.; Dumoulin, L.; Burger, J. B.

1987-11-01

350

Relationships between hysteresis measurements and the constituent properties of ceramic matrix composites. 2: Experimental studies on unidirectional materials  

Microsoft Academic Search

The use of hysteresis loop measurements for assessing the constituent properties of unidirectional CMCs is evaluated, using basic theory described in a companion paper. Results are obtained on SiC\\/CAS and SiC\\/SiC composites. These materials exhibit very different hysteresis characteristics, reflected in differences in sliding stress, Ï, and debond energy, Î{sub i}. These interface properties are manifest in the respective tensile

Jean-Marc Domergue; Emmanuel Vagaggini; Anthony G. Evans

1995-01-01

351

Use of magnetic hysteresis properties and electron spin resonance spectroscopy for the identification of volcanic ash: a preliminary study  

NASA Astrophysics Data System (ADS)

This initial study investigates the possible use of hysteresis parameters and electron spin resonance (ESR) spectroscopy to identify and correlate volcanic ash. ESR and hysteresis properties are sensitive to characteristics such as the chemical composition, mineralogy, and grain size and shape. These characteristics are determined by the tectonic setting of the volcano and by the magmatic and eruptive history of the volcanic ash. Hysteresis properties and ESR spectra, therefore, should be distinct for each ash eruption and may help to identify the eruptive source of the ash and to correlate ash from unknown sources. We conducted ESR spectroscopy at room temperature and magnetic hysteresis measurements on 19 samples of a single ash, the 1974 October 14 eruption of the Fuego volcano, Guatemala, and on single samples of ash obtained from eight different volcanoes. The Fuego ash samples were obtained at increasing distances from the volcano. For the single Fuego ash, ESR spectra and hysteresis parameters become increasingly similar as the distance from the volcano increases. At distances greater than 30km, ESR spectra and hysteresis properties are uniform. The variability of magnetic and ESR properties with distance from Fuego is due to the preferential fall-out of phenocrysts closer to the volcano. At large distances, the ash is more uniform, containing more glass and microcrystals. All eight ash samples from the different volcanoes can be distinguished from the distal Fuego 1974 October 14 ash using ESR spectra and hysteresis parameters. These results suggest that ESR and hysteresis measurements have a potential to be used as tools to identify distal ash when used in conjunction with geochemical, mineralogical and/or other types of data.

Pawse, Archana; Beske-Diehl, Suzanne; Marshall, S. A.

1998-03-01

352

New scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation  

Microsoft Academic Search

This paper presents the new scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation. When the terminal voltage Vi of the hysteresis motor running at synchronous speed is continuously increased up to nVi (n > 1) and then continuously decreased to Vi, input currents are reduced and output power is increased at the same time. Because of

Tomotsugu Kubota; Takahiro Tamura; Kazumi Kurihara

2010-01-01

353

Modeling of Hysteresis Curves of Ferroelectric Capacitor with Inhomogeneous Charged Defect Density and Polarization Parameters in the Ferroelectric Film  

Microsoft Academic Search

A method for the modeling of polarization-electric field (P-E) hysteresis curves of the inhomogeneous ferroelectric thin film capacitor was developed, considering the local electric field histories. With the present modeling method, P-E hysteresis curves can be obtained from the ferroelectric film with any distributions of inhomogeneous charged defect density N(x) and local polarization parameters such as Ps(x), Pr(x), Ec(x) and

Yong-Il Kim; Won-Jong Lee

2000-01-01

354

Period doubling and hysteresis in a periodically forced, damped anharmonic oscillator  

Microsoft Academic Search

The motion of a periodically forced, damped anharmonic oscillator governed by the equation of motion, x¨+vx˙=A2x+A4x3+A6x5+F cos(Omegat), has been studied. The analysis of the response function of this equation when treated analytically, and later, numerically, uncovers a hysteresis-type phenomenon. The stability and response of the system and the onset of period doubling have been observed through an analytical approach, and

M. Debnath; A. Roy Chowdhury

1991-01-01

355

A novel learning control strategy for hysteresis and vibration of piezo-scanners  

Microsoft Academic Search

Piezoelectric actuators have been widely utilized in micro\\/nano systems due to the high positioning resolution. A typical instance is piezo-scanners equipped in scanning probe microscopes (SPM) to implement nanoscale measurement and manipulation for various samples. However, the inherent hysteresis and structural vibration of a piezo-scanner largely limit its positioning accuracy and bandwidth, as a result, current SPM has to be

Yudong Zhang; Yongchun Fang; Xiaokun Dong; Xianwei Zhou

2009-01-01

356

"Thresholdless" hysteresis-free switching as an apparent phenomenon of surface stabilized ferroelectric liquid crystal cells.  

PubMed

The thresholdless, hysteresis-free V-shape electro-optical switching in surface-stabilized ferroelectric liquid crystals, observed usually with a triangular voltage form, has been shown to be rather an apparent and not a real effect. Strictly speaking, it is observed only at one characteristic frequency f(i) and is accompanied by an inversion of the electro-optical hysteresis direction from the normal to the abnormal one. The switching of the director in a liquid crystal layer at f(i), in reality, has a threshold and a normal hysteresis. Even the optical transmittance shows a hysteresis at f(i) when it is plotted as a function of the voltage on the liquid crystal layer and not as a function of the total voltage on the liquid crystal cell which always includes the inner insulating layers. Due to these layers, a voltage divider is formed which includes the capacitance of the insulating layers and the dynamic impedance (capacitance and resistance) of the ferroelectric liquid crystal layer. The new explanation has been confirmed by experiments with different ferroelectric liquid crystal cells combined with external resistors and capacitors and by measurements of a strong dependence of f(i) on the liquid crystal resistance which was varied over three orders of magnitude. A theoretical analysis of the problem has also been made using certain approximations for material parameters and the space dependence of the sine form of the electric field in the liquid crystal layer. The conclusions are qualitatively consistent with the experimental results. Finally, the dynamic problem has been solved numerically by taking into account of all the relevant parameters (in the absence of flow and irregularities in the cell plane) and the obtained results are in excellent correspondence with the experiment. This has been demonstrated for sets of material and cell parameters providing the best V-shape performance. PMID:12241190

Blinov, L M; Pozhidaev, E P; Podgornov, F V; Pikin, S A; Palto, S P; Sinha, A; Yasuda, A; Hashimoto, S; Haase, W

2002-08-02

357

3D modeling of contact problems and hysteresis in coupled electro-mechanics  

Microsoft Academic Search

This paper discusses the modeling of electromechanical hysteresis in devices which exhibit contact between components. We make use of a recently developed tool, CoSolve-EM, in order to solve quasistatic 3D contact electro-mechanics for a clamped-clamped beam, calculating full displacement, capacitance and contact force vs. voltage. We then extend the simulations to two design variations of the beam which permit engineering

J. R. Gilbert; G. K. Ananthasuresh; S. D. Senturia

1996-01-01

358

Nonhysteretic behavior inside the hysteresis loop of VO2 and its possible application in infrared imaging  

Microsoft Academic Search

In the resistive phase transition in VO2, temperature excursions taken from points on the major hysteresis loop produce minor loops. For sufficiently small excursions these minor loops degenerate into single-valued, nonhysteretic branches (NHBs) linear in log(rho) versus T and having essentially the same or even higher temperature coefficient of resistance (TCR) as the semiconducting phase at room temperature. We explain

M. Gurvitch; S. Luryi; A. Polyakov; A. Shabalov

2009-01-01

359

Comparative study on stress–strain hysteresis response of SAC solder joints under thermal cycles  

Microsoft Academic Search

The present study attempts to evaluate the stress-strain hysteresis responses of SAC solder joints in Resistor and FleXBGA144\\u000a packages subjected to thermal cyclic loading using several constitutive models. The total deformation of the solder material\\u000a consists of elastic, rate-independent plastic and rate-dependent creep components. The constitutive models discussed in this\\u000a study each weighted elastic, plastic and creep deformations differently. At

Alireza Shirazi; Ahmad Varvani-Farahani; Hua Lu

2008-01-01

360

Solar cycle hysteresis on F-region electron concentration peak heights over Tucuman  

Microsoft Academic Search

Ionospheric models (or numerical maps) usually depend on a solar activity index (e.g. sunspot number Rz or Covington index F10.7). The relevant relations are, however, not always the same in the ascending and descending parts of a solar cycle. As shown in a previous paper cycle 21, distinct from cycle 20, shows a strong “hysteresis” of foF2. In the present

N. Ortiz de Adler; J. R. Manzano

1995-01-01

361

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

362

Novel hysteresis effect in ultrathin epitaxial Gd2O3 high-k dielectric  

Microsoft Academic Search

Charge trapping in ultrathin high-k Gd2O3 dielectric leading to appearance of hysteresis in C-V curves is studied by capacitance-voltage, conductance-frequency and current-voltage techniques at different temperatures. It was shown that the large leakage current at a negative gate voltage causes the reversible trapping of the positive charge in the dielectric layer, without electrical degradation of the dielectric and dielectric- semiconductor

A. N. Nazarov; Y. V. Gomeniuk; Y. Y. Gomeniuk; V. S. Lysenko; H. D. B. Gottlob; M. Schmidt; M. Czernohorsky; H. J. Osten

363

Size-dependent hysteresis and phase formation kinetics during temperature cycling of metal nanopowders.  

PubMed

We present a description of the evolution of a polymorphically transforming metal nanoparticle ensemble subjected to a temperature cycling with constant rates of temperature change. The calculations of the time dependence of the volume fraction of the new phase show the existence of size-dependent hysteresis and its main features. The statistical analysis makes it possible to introduce and determine the size-dependent superheating limit and supercooling limit. PMID:21613730

Shirinyan, A S; Bilogorodskyy, Y S; Wilde, G; Schmelzer, J W P

2011-05-26

364

Tailoring anisotropic magnetoresistance and giant magnetoresistance hysteresis loops with spin-polarized current injection  

SciTech Connect

Current pulses were injected into magnetic nanowires. Their effect on the magnetoresistance hysteresis loops was studied for three morphologies: homogeneous Ni wires, copper wires containing five cobalt/copper bilayers, and hybrid structures composed of a homogeneous Ni half wire and a multilayered Co/Cu half wire. The characteristic features of the action of the current on the magnetization are shown and discussed. {copyright} 2001 American Institute of Physics.

Wegrowe, J.-E.; Kelly, D.; Hoffer, X.; Guittienne, Ph.; Ansermet, J.-Ph.

2001-06-01

365

Hysteresis and multistability in networks of bistable stochastic elements with global interaction  

NASA Astrophysics Data System (ADS)

We demonstrate the existence of the first-order phase transitions and hysteresis in a network of bistable stochastic elements with global interaction subject to additive white noise. Using the Fokker Planck equation approach, we present a method which allows one to use a continuation technique (AUTO) to follow the stationary one-particle distribution density in the space of system parameters. In addition, the Gaussian approximation is employed to compute the loci of the bifurcation points.

Pototsky, A.; Janson, N. B.

2008-11-01

366

Periodic Motions, Bifurcation, and Hysteresis of the Vibro-Impact System  

Microsoft Academic Search

Stability periodic motions, saddle-node, grazing and periodic doubling bifurcation conditions for the single-degree-of-freedom impact oscillator are determined analytically and numerically. The regions for such condition are developed in parameter space. The Poincaré map of the system is established. The period-1 impact motion of the system and its stability are studied by analytical methods, and the physical origin of hysteresis is

Jianlian Cheng; Hui Xu

2007-01-01

367

Hysteresis and delta modulation control of converters using sensorless current mode  

Microsoft Academic Search

Sensorless current mode (SCM) is a control formulation for dc-dc converters that results in voltage-source characteristics, excellent open-loop tracking, and near-ideal source rejection. Hysteresis and delta modulation are well-known, easy-to-construct large-signal methods for switched systems. Combining either large-signal method with SCM creates a controller that is simpler and more robust than a pulse-width modulation (PWM) based controller. The small-signal advantages

Jonathan W. Kimball; Philip T. Krein; Yongxiang Chen

2006-01-01

368

Hysteresis and delta modulation control of buck converters with sensorless current mode  

Microsoft Academic Search

Sensorless current mode (SCM) is a control formulation for dc-dc converters that results in voltage-source characteristics, excellent open-loop tracking, and near-ideal source rejection. Hysteresis and delta modulation are well-known, easy-to-construct large-signal methods for switched systems. Combining either large-signal method with SCM creates a controller that is simpler and more robust than a pulse-width modulation (PWM) based controller. These approaches can

Mahdi Shaneh; Khalil Rahimi; Majid Pakdel

2008-01-01

369

Coupled Brownian motors: Anomalous hysteresis and zero-bias negative conductance  

NASA Astrophysics Data System (ADS)

We introduce a model of interacting Brownian particles in a symmetric, periodic potential that undergoes a noise-induced non-equilibrium phase transition. The associated spontaneous symmetry breaking entails a ratchet-like transport mechanism. In response to an external force we identify several novel features; among the most prominent being a zero-bias negative conductance and a prima facie counterintuitive, anomalous hysteresis.

Reimann, P.; Kawai, R.; Van den Broeck, C.; Hänggi, P.

1999-03-01

370

Hysteresis in Electron-Emission Current of an Axial Electron Gun Used for Evaporation of Metals  

Microsoft Academic Search

Hysteresis of electron-emission current from filament cathode was observed in a 10-kW axial electron gun used for evaporation of metals. It was observed that in the forward direction of power change (i.e., increasing electron-beam (e-beam) power), the required filament-heating current for a specified e-beam current was significantly higher than the filament current required in the backward direction (i.e., decreasing e-beam

Biswaranjan Dikshit; M. S. Bhatia

2007-01-01

371

Thermal output of a current-carrying ferromagnetic wire: hysteresis loss versus Joule heat  

NASA Astrophysics Data System (ADS)

When an alternating current flows through a ferromagnetic wire, its thermal output is higher than predicted by the familiar Joule law. An additional contribution arises from the heat liberated due to the hysteresis loss in the self-induced magnetic field inside the wire. Simple calculations, based on the formulae derived here, show that in some cases this contribution may be comparable to, or even larger than, the Joule heat.

Ogorelec, Z.

1999-05-01

372

Color-gradient lattice Boltzmann model for simulating droplet motion with contact-angle hysteresis  

NASA Astrophysics Data System (ADS)

Lattice Boltzmann method (LBM) is an effective tool for simulating the contact-line motion due to the nature of its microscopic dynamics. In contact-line motion, contact-angle hysteresis is an inherent phenomenon, but it is neglected in most existing color-gradient based LBMs. In this paper, a color-gradient based multiphase LBM is developed to simulate the contact-line motion, particularly with the hysteresis of contact angle involved. In this model, the perturbation operator based on the continuum surface force concept is introduced to model the interfacial tension, and the recoloring operator proposed by Latva-Kokko and Rothman is used to produce phase segregation and resolve the lattice pinning problem. At the solid surface, the color-conserving wetting boundary condition [Hollis , IMA J. Appl. Math.IJAMDM0272-496010.1093/imamat/hxr008 76, 726 (2011)] is applied to improve the accuracy of simulations and suppress spurious currents at the contact line. In particular, we present a numerical algorithm to allow for the effect of the contact-angle hysteresis, in which an iterative procedure is used to determine the dynamic contact angle. Numerical simulations are conducted to verify the developed model, including the droplet partial wetting process and droplet dynamical behavior in a simple shear flow. The obtained results are compared with theoretical solutions and experimental data, indicating that the model is able to predict the equilibrium droplet shape as well as the dynamic process of partial wetting and thus permits accurate prediction of contact-line motion with the consideration of contact-angle hysteresis.

Ba, Yan; Liu, Haihu; Sun, Jinju; Zheng, Rongye

2013-10-01

373

Investigations of magnetic hysteresis of barium ferrite using the torsion pendulum method  

SciTech Connect

The magnetic stiffness is measured by the torsion pendulum method as a function of the applied field. Measurements are performed on random assemblies of chemically coprecipitated barium ferrite powders. The magnetic stiffness for both minor and major loops of the hysteresis cycle is measured and compared with calculated curves based on the model of coherent rotation. The discrepancies between theory and experiment are partly due to the effect of magnetic interaction.

Richter, H.J.; Hempel, K.A.

1988-11-15

374

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

375

Restricted access: on the nature of adsorption/desorption hysteresis in amorphous, microporous polymeric materials.  

PubMed

The phenomenon of low-pressure adsorption/desorption hysteresis, which is commonly observed in microporous polymers, is investigated by detailed gas adsorption studies. Diffusional limitations by pore blocking effects, which arise as a consequence of the micropore morphology and connectivity, are discussed as the origin of the hysteresis rather than swelling effects, which have been suggested previously. Micropores with narrow openings, which cannot be filled easily, are expected to be present next to open pores. Those pores are termed restricted-access pores and are only filled in the course of the adsorption process as a consequence of the increasing solvation pressure exhibited from already filled micropores. As a consequence of the results presented here, it is suggested to use the desorption branch in addition to the adsorption branch for the extraction of the porosity characteristics, such as specific surface area, pore volume, and pore size distribution. The magnitude of the low-pressure hysteresis might hence give an idea of the micropore connectivity, which is important information for potential applications. PMID:24079886

Jeromenok, Jekaterina; Weber, Jens

2013-10-11

376

Artificial pumping errors in the Kool Parker scaling model of soil moisture hysteresis  

NASA Astrophysics Data System (ADS)

Hysteresis models that eliminate the artificial pumping errors associated with the Kool Parker (KP) soil moisture hysteresis model, such as the Parker Lenhard (PL) method, can be computationally demanding in unsaturated transport models since they need to retain the wetting drying history of the system. The pumping errors in these models need to be eliminated for correct simulation of cyclical systems (e.g. transport above a tidally forced watertable, infiltration and redistribution under periodic irrigation) if the soils exhibit significant hysteresis. A modification is made here to the PL method that allows it to be more readily applied to numerical models by eliminating the need to store a large number of soil moisture reversal points. The modified-PL method largely eliminates any artificial pumping error and so essentially retains the accuracy of the original PL approach. The modified-PL method is implemented in HYDRUS-1D (version 2.0), which is then used to simulate cyclic capillary fringe dynamics to show the influence of removing artificial pumping errors and to demonstrate the ease of implementation. Artificial pumping errors are shown to be significant for the soils and system characteristics used here in numerical experiments of transport above a fluctuating watertable.

Werner, Adrian D.; Lockington, David A.

2006-06-01

377

Extracting the hysteresis loops of magnetic interfaces from optical second-harmonic intensity measurements  

NASA Astrophysics Data System (ADS)

Surface- and interface-sensitive optical techniques, such as optical second-harmonic generation (SHG), allow the buried interfacial structure of centrosymmetric materials to be explored through thin capping layers, and magnetic SHG (MSHG) extends this to magnetic interfaces. However, the variation of the MSHG intensity with magnetic field does not measure hysteresis loops directly, because the loops are displaced by an amount dependent on the crystallographic response and its phase difference with respect to the magnetic response, and also because there is a quadratic magnetization contribution to the SH intensity that may be significant. Two new procedures are reported for extracting hysteresis loops directly from the MSHG intensity. The first is applicable to all magnetic interfaces, including exchange-biased structures, where the saturation magnetization for positive and negative magnetic fields is equal and opposite. The second applies to all centrosymmetric hysteresis loops. These procedures correct for the quadratic response, allowing experimental geometries to be chosen that maximize the magnetic contribution, thus improving the signal-to-noise ratio and the sensitivity of the technique.

McGilp, J. F.; Carroll, L.; Fleischer, K.

2007-10-01

378

Hysteresis and reluctance electric machines with bulk HTS elements. Recent results and future development  

NASA Astrophysics Data System (ADS)

Two new types of HTS electric machine are considered. The first type is hysteresis motors and generators with cylindrical and disc rotors containing bulk HTS elements. The second type is reluctance motors with compound HTS-ferromagnetic rotors. The compound HTS-ferromagnetic rotors, consisting of joined alternating bulk HTS (YBCO) and ferromagnetic (iron) plates, provide a new active material for electromechanical purposes. Such rotors have anisotropic properties (ferromagnetic in one direction and diamagnetic in the perpendicular one). Theoretical and experimental results for HTS hysteresis and reluctance motors are presented. A series of hysteresis HTS motors with output power rating from 1 kW (at 50 Hz) up to 4 kW (at 400 Hz) and a series of reluctance HTS motors with output power 2-18.5 kW (at 50 Hz) were constructed and successfully tested. It was shown that HTS reluctance motors could reach two to five times better overall dimensions and specific power than conventional asynchronous motors of the same size and will have higher values of power factor (cos ??0.7 to 0.8).

Kovalev, L. K.; Ilushin, K. V.; Penkin, V. T.; Kovalev, K. L.; M-A Koneev, S.; Poltavets, V. N.; Larionoff, A. E.; Modestov, K. A.; Larionoff, S. A.; Gawalek, W.; Habisreuther, T.; Oswald, B.; Best, K.-J.; Strasser, T.

2000-05-01

379

[Process study on hysteresis of vegetation cover influencing sand-dust events].  

PubMed

Data analysis from satellite and weather stations during 1982-2000 shows nonlinear relationship between vegetation cover and sand-dust events is present in most part of China. Vegetation cover ratio in summer can impact significantly on the frequency of sand-dust storms from winter to spring in the source regions of sand-dust events. It is not quite clear about the hysteresis that vegetation cover in summer influence sand-dust events during winter and spring. A quasi-geostrophic barotropic model is used under the condition of 3 magnitude of frictional coefficient to investigate the cause of the hysteresis. Wind velocity shows a greatest decline at 90% during 72 h as initial wind velocity is 10 m/s for magnitude of frictional coefficient between atmosphere and water surface, greatest decline at 100% during 18 h for magnitude of frictional coefficient between atmosphere and bare soil and a 100% reduction of wind speed during 1 h for magnitude of frictional coefficient between atmosphere and vegetation cover. Observation and simulation prove that residual root and stem from summervegetation are one of factors to influence sand-dust events happened during winter and spring. Air inhibition from residual root and stem is a most important reason for hysteresis that vegetation cover influence sand-dust events. PMID:19402476

Xu, Xing-Kui; Wang, Xiao-Tao; Zhang, Feng

2009-02-15

380

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

381

General contact and hysteresis analysis of multidielectric MEMS devices under thermal and electrostatic actuation  

NASA Astrophysics Data System (ADS)

Many MEMS devices which are thermally and/or electrostatically actuated contain moveable components which may undergo contact. The behavior is further complicated when hysteresis is exhibited after contact. Generally, MEMS devices consist of multiple materials with different mechanical and electrical properties. These factors pose a challenge for modeling highly non-linear MEMS behavior. This paper present an improved approach to modeling contact and hysteresis between any two bodies in a MEMS device. In particular, the three assumptions are relaxed. First, previous methods for modeling contact were able to model only a single dielectric layer. The new approach is capable of modeling multi-dielectric layers. Second, previous modeling methods required the specification of contact faces. This restriction has been generalized to specifying contact entities. Third, previously, modeling methods required an air stop gap assumption above a conductor to avoid numerical difficulties in electrostatic calculations. The new approach developed removes the air stop gap assumption. More realistic mechanical contact is simulated. Electrostatic and thermal driven actuation is considered. A number of case examples is presented to demonstrate the utility of the new contact and hysteresis approach. First a suspended test-beam structure is analyzed under different sets of boundary constraints and loading. Then, contact of an electrostatically actuated deformable mirror is analyzed.

He, Yie; Marchetti, James; Gallegos, Carlos

1999-03-01

382

Magnetic hysteresis studies of Tl-2223 substituted by Fe and Zn  

NASA Astrophysics Data System (ADS)

Effect of Fe and Zn substitutions on the magnetic hysteresis of Tl-2223 are investigated in high magnetic fields up to 9 Tesla and at different temperatures (T= 6, 20, 40 and 80 K). The results of magnetic hysteresis loops show that the area of these loops decreases as Fe-content increases, whereas it increases for Zn-substitutions till x = 0.2 and then decreases for x > 0.2. The magnetization difference ?M is found to decay exponentially with temperature at low magnetic fields, according to ?M ? exp (-T/T0). The characteristic temperature T0 is found to be varied from 6 K to 40 K and it is related to the applied magnetic field B according to T0? B-1/n. The critical current density is calculated for the prepared samples from magnetic hysteresis measurements and compared with that determined from ac magnetic susceptibility. The results are discussed according to the flux motion and flux pinning.

Abou-Aly, Aly; Awad, Ramadan; Ibrahim, Ibrahim; Faraj, Ahmed

2009-03-01

383

Nonequilibrium hysteresis and Wien effect water dissociation at a bipolar membrane  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

384

Effects of size distribution on hysteresis losses of magnetic nanoparticles for hyperthermia  

NASA Astrophysics Data System (ADS)

For understanding hysteresis losses of magnetic nanoparticles to be used for magnetic particle hyperthermia the effect of size distribution on the dependence of hysteresis losses on magnetic field amplitude is studied on the basis of a phenomenological model in the size range from superparamagnetism to magnetic multi-domains—roughly 10 up to 100 nm. Relying on experimental data for the size dependence of coercivity, an empirical expression for the dependence of hysteresis loss on field amplitude and particle size is derived for hypothetical monodisperse particle ensembles. Considering experimentally observable size distributions, the dependence of loss on distribution parameters—mean particle size and variance—is studied. There, field amplitude is taken into account as an important parameter, which for technical and biomedical reasons in hyperthermia equipment is restricted. Experimental results for different particle types with mean diameter of 30 nm may be well reproduced theoretically if a small loss contribution of Rayleigh type is taken into account. Results show that the Stoner-Wohlfarth model for single domain magnetization reversal via homogeneous rotation cannot explain experimental observations. In particular, in magnetosomes which are distinguished by nearly ideal crystallographic shapes and narrow size distribution large friction-like losses occur even for small field amplitude. Parameters of the high frequency field for hyperthermia (amplitude and frequency) as well as of the size distribution of applied particles are discussed with respect to attaining maximum specific heating power.

Hergt, Rudolf; Dutz, Silvio; Röder, Michael

2008-09-01

385

Dynamic hysteresis in a one-dimensional Ising model: Application to allosteric proteins  

NASA Astrophysics Data System (ADS)

We solve exactly the problem of dynamic hysteresis for a finite one-dimensional Ising model at low temperature. We find that the area of the hysteresis loop, as the field is varied periodically, scales as the square root of the field frequency for a large range of frequencies. Below a critical frequency there is a correction to the scaling law, resulting in a linear relationship between hysteresis area and frequency. The one-dimensional Ising model provides a simplified description of switchlike behavior in allosteric proteins, such as hemoglobin. Thus our analysis predicts the switching dynamics of allosteric proteins when they are exposed to a ligand concentration which changes with time. Many allosteric proteins bind a regulator that is maintained at a nonequilibrium concentration by active signal transduction processes. In the light of our analysis, we discuss to what extent allosteric proteins can respond to changes in regulator concentration caused by an upstream signaling event, while remaining insensitive to the intrinsic nonequilibrium fluctuations in regulator level which occur in the absence of a signal.

Graham, I.; Duke, T. A. J.

2005-06-01

386

Preparation and investigation of sputtered vanadium dioxide films with large phase-transition hysteresis loops  

NASA Astrophysics Data System (ADS)

Vanadium dioxide (VO2) films with large phase-transition hysteresis loops were fabricated on glass substrates by reactive direct current (DC) magnetron sputtering in Ar/O2 atmosphere and subsequent in situ annealing process in pure oxygen. The crystal structure, chemical composition, morphology and metal-insulator transition (MIT) properties of the deposited films were investigated. The results reveal that the films show a polycrystalline nature with a (0 1 1) preferred orientation and consist of small spheroidal nanoparticles. All the deposited VO2 films show large hysteresis loops due to the small density of nucleating defects and the large interfacial energies, which are determined by the characteristics of the particles in the films, namely the small transversal grain size and the spheroidal shape. The film comprising the smallest spheroidal nanoparticles not only shows a large hysteresis width of 36.3 °C but also shows a low transition temperature of 32.2 °C upon cooling. This experiment facilitates the civilian applications of the VO2 films on glass substrates in optical storage-type devices.

Zhang, Huafu; Wu, Zhiming; He, Qiong; Jiang, Yadong

2013-07-01

387

Hysteresis effects in a motor task with cotton-top tamarins (Sanguinus oedipus).  

PubMed

The way human adults grasp an object is influenced by their recent history of motor actions. Previously executed grasps are often more likely to reoccur on subsequent grasps. This type of hysteresis effect has been incorporated into cognitive models of motor planning, suggesting that when planning movements, individuals tend to reuse recently used plans rather than generating new plans from scratch. To the best of our knowledge, the phylogenetic roots of this phenomenon have not been investigated. Here, the authors asked whether 6 cotton-top tamarin monkeys (Saguinus oedipus) would demonstrate a hysteresis effect on a reaching task. The authors tested the monkeys by placing marshmallow pieces within grasping distance of a hole through which the monkeys could reach. On subsequent trials, the marshmallow position changed such that it progressed in an arc in either a clockwise or counterclockwise direction. The authors asked whether the transition point in right- versus left-handed reaches would differ depending on the direction of the progression. The data supported this hysteresis prediction. The outcome provides additional support for the notion that human motor planning strategies may have a lengthy evolutionary history. PMID:19594287

Weiss, Daniel J; Wark, Jason

2009-07-01

388

Hysteresis Modeling of Magnetic Shape Memory Alloy Actuator Based on Krasnosel'skii-Pokrovskii Model  

PubMed Central

As a new type of intelligent material, magnetically shape memory alloy (MSMA) has a good performance in its applications in the actuator manufacturing. Compared with traditional actuators, MSMA actuator has the advantages as fast response and large deformation; however, the hysteresis nonlinearity of the MSMA actuator restricts its further improving of control precision. In this paper, an improved Krasnosel'skii-Pokrovskii (KP) model is used to establish the hysteresis model of MSMA actuator. To identify the weighting parameters of the KP operators, an improved gradient correction algorithm and a variable step-size recursive least square estimation algorithm are proposed in this paper. In order to demonstrate the validity of the proposed modeling approach, simulation experiments are performed, simulations with improved gradient correction algorithm and variable step-size recursive least square estimation algorithm are studied, respectively. Simulation results of both identification algorithms demonstrate that the proposed modeling approach in this paper can establish an effective and accurate hysteresis model for MSMA actuator, and it provides a foundation for improving the control precision of MSMA actuator.

Wang, Shoubin; Gao, Wei

2013-01-01

389

Hysteresis modeling of magnetic shape memory alloy actuator based on Krasnosel'skii-Pokrovskii model.  

PubMed

As a new type of intelligent material, magnetically shape memory alloy (MSMA) has a good performance in its applications in the actuator manufacturing. Compared with traditional actuators, MSMA actuator has the advantages as fast response and large deformation; however, the hysteresis nonlinearity of the MSMA actuator restricts its further improving of control precision. In this paper, an improved Krasnosel'skii-Pokrovskii (KP) model is used to establish the hysteresis model of MSMA actuator. To identify the weighting parameters of the KP operators, an improved gradient correction algorithm and a variable step-size recursive least square estimation algorithm are proposed in this paper. In order to demonstrate the validity of the proposed modeling approach, simulation experiments are performed, simulations with improved gradient correction algorithm and variable step-size recursive least square estimation algorithm are studied, respectively. Simulation results of both identification algorithms demonstrate that the proposed modeling approach in this paper can establish an effective and accurate hysteresis model for MSMA actuator, and it provides a foundation for improving the control precision of MSMA actuator. PMID:23737730

Zhou, Miaolei; Wang, Shoubin; Gao, Wei

2013-04-28

390

Gadolinium nanoparticle based switchable mirrors: quenching of hydrogenation-dehydrogenation hysteresis.  

PubMed

A continuous and reversible 'structural, optical, and electronic' transition between the reflecting metallic dihydride and transparent semiconducting trihydride states observed in rare earth metals on hydrogenation make these materials and their hydrides suitable for switchable mirror, sensing, and other technological applications. Recently Pd capped Gd nanoparticle based 'new generation' switchable mirrors have been fabricated with extended color neutrality, better optical contrast, and faster kinetics in comparison to the polycrystalline, epitaxial, alloy, and multilayer films. The present report aims at investigating the effect of nanoparticle nature on the hydrogenation-dehydrogenation hysteresis in switchable mirrors by carrying out in situ measurement of optical transmittance and electrode potentials during electrochemical hydrogen loading-deloading of Gd nanoparticle samples. Interestingly, Gd nanoparticle samples were observed to exhibit quenched hysteresis. The quenching of hysteresis in hydrogen-induced properties has been attributed to the absence of structural transition upon hydrogenation, reduction in topographical interlocking of the grains and elimination of lateral clamping of the slack nanoparticle layer to the substrate. PMID:17654936

Aruna, I; Mehta, B R; Malhotra, L K

2007-06-01

391

Hysteresis force loss and damping properties in a practical magnet superconductor maglev test vehicle  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

392

Hysteresis properties of magnetic spherules and whole rock specimens from some Paleozoic platform carbonate rocks  

NASA Astrophysics Data System (ADS)

It is widely established that many Paleozoic carbonate rocks were remagnetized during the late Paleozoic Kiaman reversed superchron. Yet the paleomagnetic recorders of this event have remained elusive. Magnetic spherules have been candidates for this role, because they are probably authigenic. Therefore we have studied the hysteresis properties of individual magnetic spherules from two formations, the remagnetized Onondaga (Devonian, New York) and the effectively unremagnetized Wabash (Silurian, Indiana). Also, we have compared the hysteresis properties of spherules to those of remagnetized limestones from the Onondaga, Trenton (Ordovician, New York), and Helderberg (Devonian, New York) formations and from the unremagnetized Wabash formation. The spherules studied here vary from about 20 µm to over 100 µm in diameter. Nevertheless, on the basis of hysteresis behavior this spherule population spans the full range of domain states, from truly multidomain (MD) to pseudo-single-domain (PSD) to single domain (SD). Because these spherules are so large, it is remarkable that more than half display the highly PSD-like behavior typical of many remagnetized carbonate rocks. Equally as remarkable is the lack of dependence on spherule size of various hysteresis properties such as coercive force (Hc), remanent coercive force (Hcr), the ratio of saturation remanence to saturation moment (Mrs/Ms), and the ratio of remanent coercive force to coercive force (Hcr/Hc). These findings dispel the preconception that large spherules are too magnetically soft to be stable carriers of ancient magnetization. Surprisingly, Onondaga and Wabash spherules yield virtually identical suites of hysteresis properties. On the one hand, this high degree of similarity could indicate that spherules are irrelevant to remagnetization. More intriguing, however, is that this similarity could mean that the Wabash formation, although effectively unremagnetized, nevertheless contains magnetic mineralogical traces of a regional remagnetization event. It is significant that for these spherules a bilogarithmic plot of Mrs/Ms versus Hcr/Hc does not define a simple linear trend. Instead, Mrs/Ms increases more rapidly with decreasing Hcr/Hc for spherules in the PSD range than in the MD range. When a power law is fit solely to the hysteresis ratios of PSD-like to SD-like spherules, extrapolation to the SD limit gives Mrs/Ms = 0.75. Similarly, a power law fit to the hysteresis ratios obtained here from remagnetized carbonate rocks yields Mrs/Ms = 0.72 at the SD boundary. These results could indicate that a large percentage of SD-like spherules, like the SD carriers in remagnetized carbonate rocks, are governed by magnetocrystalline anisotropy. Finally, the present data point to values of Hc near 350 Oe both for SD-like spherules and for the SD grains thought to carry remanence in remagnetized carbonates. Clearly, PSD- and SD-like spherules share several key rock magnetic properties with remagnetized carbonate rocks. Thus spherules still are likely candidates for carrying the remagnetization signal.

Suk, Dongwoo; Halgedahl, Susan L.

1996-11-01

393

Modelling of hysteresis using Masing Bouc-Wen’s framework and search of conditions for the chaotic responses  

NASA Astrophysics Data System (ADS)

In the present work hysteresis is simulated by means of internal variables. It was shown that Masing's imitating mechanism of the energy dissipation presented in the differential equations of Bouc-Wen's structure allows to simulate hysteresis from very different fields. The constructed analytical models of different types of hysteresis loops are simple, enable major and minor loops reproducing and provide a high degree of correspondence with experimental data. The models of such structure are convenient for the further investigation. Hysteretic systems under harmonic excitation described by models of such structure may reveal chaotic behaviour. Using an effective algorithm based on analysis of the wandering trajectories [1-4,22,23], an evolution of chaotic behaviour regions of oscillators with hysteresis is presented in various parametric planes. Substantial influence of a hysteretic dissipation value on the form and location of these regions, and also restraining and generating effects of the hysteretic dissipation on a chaos occurrence are ascertained. Conditions for pinched hysteresis are defined.

Awrejcewicz, Jan; Dzyubak, Larisa; Lamarque, Claude-Henri

2008-07-01

394

Low-hysteresis materials for magnetic refrigeration: Gd/sub 1-x/Er/sub x/Al/sub 2/  

SciTech Connect

The series of ferromagnetic intermetallics Gd/sub 1-x/Er/sub x/Al/sub 2/ are candidate working materials for magnetic refrigeration because of their large moment, small anisotropy, and the fact that their Curie temperatures span the range 14 K to 164 K. We have measured the magnitude of the magnetic hysteresis as a function of temperature from 4 K to T/sub c/ for polycrystalline samples of these materials via ac magnetic susceptibility and magnetization hysteresis loops. We found, as expected, virtually no hysteresis in GdAl/sub 2/, and more surprisingly, less than 3000 A/m hysteresis in ErAl/sub 2/, and 2 x 10/sup 4/ A/m in Gd/sub 0/ /sub 5/Er/sub 0/ /sub 5/Al/sub 2/. Moreover, the hysteresis in Gd/sub 0/ /sub 5/Er/sub 0/ /sub 5/Al/sub 2/ was less than or equal to 100 A/m for T - T/sub c/ < 20 K.

Zimm, C.B.; Barclay, J.A.; Johanson, W.R.

1983-01-01

395

Measurement method for determining the magnetic hysteresis effects of reluctance actuators by evaluation of the force and flux variation  

NASA Astrophysics Data System (ADS)

A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.

Vrijsen, N. H.; Jansen, J. W.; Compter, J. C.; Lomonova, E. A.

2013-07-01

396

Modeling of Hysteresis Curves of Ferroelectric Capacitor with Inhomogeneous Charged Defect Density and Polarization Parameters in the Ferroelectric Film  

NASA Astrophysics Data System (ADS)

A method for the modeling of polarization-electric field (P-E) hysteresis curves of the inhomogeneous ferroelectric thin film capacitor was developed, considering the local electric field histories. With the present modeling method, P-E hysteresis curves can be obtained from the ferroelectric film with any distributions of inhomogeneous charged defect density N(x) and local polarization parameters such as Ps(x), Pr(x), Ec(x) and \\varepsilonf(x), and the separate or combined effect of the parameters on the P-E hysteresis curve can be investigated. It was found that microscopic variations of the charged defect density in the ferroelectric film induce asymmetry and voltage shift in the hysteresis curve. How much and in which direction the voltage shift occurs are determined by the concentration distribution of the charged defects and their signs. Inhomogeneity of the other local polarization parameters in the ferroelectric film has no effects on the voltage shift of the P-E hysteresis curves. However, when they combined with the inhomogeneity of the charged defect density, the voltage shift induced by the inhomogeneous charged defect is generally enhanced. The effects of the model parameters on the apparent Ps and Pr values were also investigated.

Kim, Yong-Il; Lee, Won-Jong

2000-03-01

397

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

398

Hysteresis of heart rate and heat exchange of fasting and postprandial savannah monitor lizards (Varanus exanthematicus).  

PubMed

Reptiles are ectothermic, but regulate body temperatures (T(b)) by behavioural and physiological means. Body temperature has profound effects on virtually all physiological functions. It is well known that heating occurs faster than cooling, which seems to correlate with changes in cutaneous perfusion. Increased cutaneous perfusion, and hence elevated cardiac output, during heating is reflected in an increased heart rate (f(H)), and f(H), at a given T(b), is normally higher during heating compared to cooling ('hysteresis of heart rate'). Digestion is associated with an increased metabolic rate. This is associated with an elevated f(H) and many species of reptiles also exhibited a behavioural selection of higher T(b) during digestion. Here, we examine whether digestion affects the rate of heating and cooling as well as the hysteresis of heart rate in savannah monitor lizards (Varanus exanthematicus). Fasting lizards were studied after 5 days of food deprivation while digesting lizards were studied approximately 24 h after ingesting dead mice that equalled 10% of their body mass. Heart rate was measured while T(b) increased from 28 to 38 degrees C under a heat lamp and while T(b) decreased during a subsequent cooling phase. The lizards exhibited hysteresis of heart rate, and heating occurred faster than cooling. Feeding led to an increased f(H) (approximately 20 min(-1) irrespective of T(b)), but did not affect the rate of temperature change during heating or cooling. Therefore, it is likely that the increased blood flows during digestion are distributed exclusively to visceral organs and that the thermal conductance remains unaffected by the elevated metabolic rate during digestion. PMID:15123175

Zaar, Morten; Larsen, Einer; Wang, Tobias

2004-04-01

399

Water movement in glass bead porous media: 1. Experiments of capillary rise and hysteresis  

NASA Astrophysics Data System (ADS)

Experimental observations of capillary rise and hysteresis of water or ethanol in glass beads are presented to improve our understanding of those physical processes in porous media. The results provide evidence that capillary rise into porous media cannot be fully explained by a model of cylinders. They further demonstrate that the "Ink bottle" model does not provide an adequate explanation of hysteresis. Glass beads serving as a model for ideal soil are enclosed in a rectangular glass chamber model. A TV camera associated with a microscope was used to record the processes of capillary rise and drainage. It is clearly shown during capillary rise that the fluid exhibits a "jump" behavior at the neck of the pores in an initially dry profile or at the bottom of the water film in an initially wet profile. Under an initially dry condition, the jump initiates at the particle with smallest diameter. The jump process continues to higher elevations until at equilibrium the surface tensile force is balanced by the hydrostatic force. The wetting front at that time is readily observed as flat and saturated. Under an initially wet condition, capillary rise occurs as a water film thickening process associated with the jump process. Trapped air behind the wetting front renders the wetting front irregular and unsaturated. The capillary rise into an initially wet porous medium can be higher than that into an initially dry profile. During the drying process, large surface areas associated with the gas-liquid interface develop, allowing the porous medium to retain more water than during the wetting process at the same pressure. That mechanism explains better the hysteresis phenomenon in porous media in contrast to other mechanisms that now prevail.

Lu, T. X.; Biggar, J. W.; Nielsen, D. R.

1994-12-01

400

Hysteresis, thermomagnetic, and low-temperature magnetic properties of Southwestern U.S. obsidians  

NASA Astrophysics Data System (ADS)

Geochemical signatures of Southwestern U.S. obsidians have been intensively studied, in part to use as a provenance method for archaeological obsidians (Shackley, 2005). We reported (Sternberg et al. 2010) examined magnetic properties of 50 unoriented samples from 10 geologic obsidian sources in Arizona, Nevada, and New Mexico; here we provide additional results measured at the Institute for Rock magnetism. Room-temperature hysteresis curves were measured using a vibrating sample magnetometer on 58 specimens from all 50 samples. The Quantum Designs Magnetic Properties Measurement System was used to measure low temperature cycling of the natural remanence and/or of a room-temperature saturation isothermal remanence for 10 specimens, and frequency dependence of susceptibility for 7 specimens. A Princeton VSM was used to measure hysteresis curves and thermomagnetic curves for 19 specimens from 17 samples. Eleven of the thermomagnetic curves show Curie temperatures close to that for magnetite, and most of them are almost perfectly reversible. Many of the specimens also show a less well-defined Curie point around 150-200°C; for a few specimens the thermomagnetic behavior is dominated by paramagnetic iron and no ferromagnetic phases can be identified. The low-temperature remanence and susceptibility measurements show the magnetite Verwey transition in almost all specimens, and a significant superparamagnetic presence in only a few cases. Hysteresis parameters plot mainly in the lower half of the PSD domain on a Day plot, and saturation magnetization values indicate magnetite concentrations of about 0.2% to 0.5% for most specimens. The coercivity of remanence decreased considerably for one specimen after surface cleaning, although for 5 other comparisons there was no change.

Sternberg, R. S.; Jackson, M. J.; Shackley, M. S.

2011-12-01

401

Diffraction hysteresis loop modelisation in transverse magneto-optical Kerr effect  

NASA Astrophysics Data System (ADS)

We theoretically study the diffraction of light by a magneto-optical grating for the transverse magneto-optical Kerr effect (TMOKE) case when the magnetization runs from saturation in one direction to saturation in the opposite direction. We use a vectorial theory of diffraction based on a perturbative approximation to the Rayleigh-Fano method, which leads to analytical formulae. We plot diffraction hysteresis loops (DHL) for several diffracted harmonics. We show that for a particular angle of incidence, the loop corresponding to one diffracted harmonic is flat.

Vial, Alexandre; van Labeke, Daniel

1998-07-01

402

Nanostructured Nb reinforced NiTi shape memory alloy composite with high strength and narrow hysteresis  

NASA Astrophysics Data System (ADS)

An in-situ nanostructured Nb reinforced NiTi shape-memory alloy composite was fabricated by mechanical reduction of an as-cast Nb-NiTi eutectic alloy. The composite exhibits large elastic strain, high strength, narrow hysteresis, and high mechanical energy storage density and efficiency during tensile cycling. In situ synchrotron high-energy X-ray diffraction revealed that these superior properties were attributed to the strong coupling between nanostructured Nb and NiTi matrix during deformation. Furthermore, this study offers a good understanding of the deformation behavior of the nanoscale reinforcement embedded in the metal matrix deformed by stress-induced phase transformation.

Hao, Shijie; Cui, Lishan; Jiang, Daqiang; Yu, Cun; Jiang, Jiang; Shi, Xiaobin; Liu, Zhenyang; Wang, Shan; Wang, Yandong; Brown, Dennis E.; Ren, Yang

2013-06-01

403

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

404

Optical hysteresis and multistability in a double resonator system with an additional feedback  

NASA Astrophysics Data System (ADS)

An experimental and theoretical study of optical multistability in a double resonator system formed by a thin single crystal of GaSe and an air gas separating it from a dielectric mirror is reported. The system allows one to observe various types of optical hysteresis, bi- and multistability with microsecond switching time at room temperature and submilliwatt threshold of first switching. Five stable output states are reported for a given input. A nonmonotonic input/output characteristic of the double resonator system is used to demonstrate doubling of the incident laser modulation frequency as a new example of an all-optical signal processing.

Golubev, G. P.; Luchinskii, D. G.; Velikovich, A. L.; Liberman, M. A.

1987-10-01

405

Magnetization process as a combined function of field and temperature in the product model of hysteresis  

NASA Astrophysics Data System (ADS)

In the product model of hysteresis the magnetization was proposed to be an indirect function of the magnetic field. The reversible paramagnetic and the irreversible hysteretic contributions to the magnetization appeared together as additional terms in the argument of a sigmoid type envelope function. Recent experimental data suggest that this enveloping sigmoid should be the Brillouin function. Therefore it is proposed that the mean-field theory for the temperature dependence can be generalized for the description of the combined field and temperature dependence of magnetization processes.

Kádár, György; Szabó, Zsolt

2004-05-01

406

Spin transition polymer with a large hysteresis around room temperature: optical response and electron paramagnetic resonance  

Microsoft Academic Search

A polymer compound 0953-8984\\/10\\/31\\/021\\/img9 has been studied by optical response and electron spin resonance (EPR) using 0953-8984\\/10\\/31\\/021\\/img10 and 0953-8984\\/10\\/31\\/021\\/img11 as dopants and paramagnetic probes. The transition between low-spin (LS) and high-spin (HS) states of 0953-8984\\/10\\/31\\/021\\/img12 ions occurs with a broad hysteresis loop around room temperature and is accompanied by a colour change from bright pink in the LS state to

Christophe Cantin; Hervé Daubric; Janis Kliava; Yves Servant; Line Sommier; Olivier Kahn

1998-01-01

407

Correlation between the hysteresis and the initial defect density of graphene  

NASA Astrophysics Data System (ADS)

The role of the initial defects of graphene characterized by Raman spectroscopy is correlated with the physical mechanisms causing the hysteretic device characteristics of graphene field effect transistors (FETs). Fast charging related to the tunneling-induced charge exchange is found to be closely correlated with the initial defect density, while slow charging related to environmental influences such as the water redox reaction showed a weak correlation. It can be concluded that the intrinsic quality of graphene should be improved to minimize the hysteresis of graphene FETs even in an air-tight environment.

Cho, Chunhum; Gon Lee, Young; Jung, Ukjin; Goo Kang, Chang; Lim, Sungkwan; Jun Hwang, Hyeon; Choi, Hojun; Hun Lee, Byoung

2013-08-01

408

Nonlinear susceptibility and dynamic hysteresis loops of magnetic nanoparticles with biaxial anisotropy  

NASA Astrophysics Data System (ADS)

The nonlinear ac susceptibility and dynamic magnetic hysteresis (DMH) of a single domain ferromagnetic particle with biaxial anisotropy subjected to both external ac and dc fields of arbitrary strength and orientation are treated via Brown's continuous diffusions model [W. F. Brown, Jr., Phys. Rev. 130, 1677 (1963)] of magnetization orientations. The DMH loops and nonlinear ac susceptibility strongly depend on the dc and ac field strengths, the polar angle between the easy axis of the particle, the external field vectors, temperature, and damping. In contrast to uniaxial particles, the nonlinear ac stationary response and DMH strongly depend on the azimuthal direction of the ac field and the biaxiality parameter ?.

Ouari, Bachir; Titov, Serguey V.; El Mrabti, Halim; Kalmykov, Yuri P.

2013-02-01

409

Magnetic rotational hysteresis study on spherical 85-160 nm Fe3O4 particles  

NASA Astrophysics Data System (ADS)

Rotational hysteresis losses Wr were determined as a function of magnetic field H for dispensed spherical Fe3O4 particles of mean grain sizes 85 nm, 127 nm and 162 nm between 78 K and 294 K. The observed Wr-H curves are compared with theoretical curves for single domain particles. The analysed particles reveal centers of high magnetic anisotropy. Such centers can be of importance during the generation of a thermoremanent magnetization, as they may be the origin of enhanced magnetic stability.

Schmidbauer, E.

1988-05-01

410

Angle-resolved analysis of magnetic hysteresis for micro-magnetic clusters with local deformations  

NASA Astrophysics Data System (ADS)

Magnetic dynamic process for an octagonal micro-magnetic cluster with one dislocation loop was simulated by pseudo-nonequilibrial Monte Carlo method including pseudo-dipole interaction. The results showed that the magnetic hysteresis curves of micro-magnetic clusters with one dislocation loop and of those without any deformation differ. The difference is more clearly shown for noise pattern of magnetization process, which depends on dynamic behavior of spin ensemble. A series of snapshots for spin ensemble displays that the magnetization process depends on the direction of the applied magnetic field. We propose usefulness of angle-resolved analysis of magnetic dynamic process to evaluate magnetic clusters.

Yamaguchi, Katsuhiko; Suzuki, Kenji; Nittono, Osamu; Takagi, Toshiyuki; Yamada, Koji

2008-02-01

411

Realistic threshold policy with hysteresis to control predator-prey continuous dynamics.  

PubMed

This paper introduces a threshold policy with hysteresis (TPH) for the control of one-predator one-prey models. The models studied are the Lotka-Volterra and Rosenzweig-MacArthur two species density-dependent predator-prey models and the Arditi-Ginzburg nondimensional ratio-dependent model. The proposed policy (TPH) changes the dynamics of the system in such a way that a bounded oscillation is achieved confined to a region that does not allow extinction of either species. The policy can be designed by a suitable choice of so called virtual equilibrium points in a simple and intuitive manner. PMID:19290561

Mendoza Meza, Magno Enrique; Bhaya, Amit

2009-03-17

412

Hysteresis of the shape of a magnetic fluid volume near a line conductor  

NASA Astrophysics Data System (ADS)

Hysteresis behaviour and break-up of a magnetic fluid volume situated between two concentric cylinders in the presence of magnetic field are considered analytically. The situation investigated is the break-up and the formation of the magnetic fluid volume between the cylinders and the change of the thickness of drops on the inner and outer cylinders as the line current in the inner cylinder is increased or decreased. It is shown that an adequate qualitative and numerical description of such phenomena must take into account the dependence of the fluid magnetization on the magnetic field. Tables 1, Figs 7, Refs 4.

Naletova, V. A.; Kiryushin, V. V.; Reks, A. G.; Suvchuk, E.

2008-06-01

413

Hysteresis, Discrete Memory, and Nonlinear Wave Propagation in Rock: A New Paradigm  

SciTech Connect

The structural elements in a rock are characterized by their density in Preisach-Mayergoyz space (PM space). This density is found for a Berea sandstone from stress-strain data and used to study the response of the sandstone to elaborate pressure protocols. Hysteresis with discrete memory, in agreement with experiment, is found. The relationship between strain, quasistatic modulus, and dynamic modulus is established. Nonlinear wave propagation, the production of copious harmonics, and nonlinear attenuation are demonstrated. PM space is shown to be the central construct in a new paradigm for the description of the elastic behavior of consolidated materials.

Guyer, R.A.; McCall, K.R. [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Boitnott, G.N. [New England Research Inc., 76 Olcott Drive, White River Junction, Vermont 05001 (United States)

1995-04-24

414

Quantum oscillations and ferromagnetic hysteresis observed in iron filled multiwall carbon nanotubes.  

PubMed

We report on the electrical transport properties of single multiwall carbon nanotubes with and without an iron filling as a function of temperature and magnetic field. For the iron filled nanotubes the magnetoresistance shows a magnetic behavior induced by iron, which can be explained by taking into account a contribution of s-d hybridization. In particular, ferromagnetic-like hysteresis loops were observed up to 50 K for the iron filled multiwall carbon nanotubes. The magnetoresistance shows quantum interference phenomena such as universal conductance fluctuations and weak localization effects. PMID:22155967

Barzola-Quiquia, J; Klingner, N; Krüger, J; Molle, A; Esquinazi, P; Leonhardt, A; Martínez, M T

2011-12-08

415

Separation of nonlinear and friction-like contributions to the piezoelectric hysteresis  

Microsoft Academic Search

Based on direct and converse piezoelectric measurements, our results for relaxor-ferroelectric solid solutions 0.5 Pb(Zr,Ti)O3 -0.5 Pb(Ni1\\/3Nb2\\/3)O3 (PNN-PZT) show that piezoelectric hysteresis can be better described by a coupled Rayleigh-frictional model rather than by either model separately. The nonlinear parameters yielded by such loop analysis are in a good agreement with the ones obtained from piezoelectric nonlinearity, constituting a new

Gilles Robert; Dragan Damjanovic; Nava Setter

2000-01-01

416

Coercivity dynamics and origin of time-delayed magneto-optical hysteresis loops in pump-probe Kerr spectroscopy  

NASA Astrophysics Data System (ADS)

Time-resolved magneto-optical Kerr effect (TR-MOKE) is used to measure hysteresis loops of a magnetic film at a different delayed time after femtosecond laser excitations. Coercivity dynamics of the magnetic film is obtained from TR-MOKE loops as usual. However, we point out that the dynamics of coercivity does not reflect the evolution of initial coercivity shown by the initial hysteresis loop with no laser excitation, but that of the final coercivity under laser excitation, where the final coercivity means one given by the hysteresis loop measured at a negative pump-probe delay time under pump excitation. TR-MOKE loops usually cannot track the evolution of coercivity of a magnetic system upon strong laser shot, and can do that only when the magnetic system is reversible under a low excitation. The oscillatory recovery behavior of the final coercivity is observed, and is ascribed to metastability of zero magnetization state.

Li, Shufa; Chen, Zhifeng; Cheng, Chuyuan; Li, Jiaming; Zhou, Shiming; Lai, Tianshu

2013-02-01

417

Differences of the magnetic hysteresis behaviors in the magnetostructural transformation Mn1-xVxCoGe alloys  

NASA Astrophysics Data System (ADS)

The magnetic hysteresis behaviors and the magnetocaloric properties of the Mn1-xVxCoGe (x=0.01 and 0.02) alloys in the heating and cooling runs have been investigated comparatively in the vicinity of the first-order magnetostructural phase transition. The magnetic hysteresis behaviors reveal an evident discrepancy between the heating and cooling processes. The average hysteresis losses estimated from the initial magnetization isotherms M(H) measured upon cooling are much larger than that upon heating. Considering the thermodynamics conditions and the potential barrier of phase transition, we analyzed the possible origin for this discrepancy and discussed the effects on the magnetocaloric properties for these two alloys.

Ma, S. C.; Zhong, Z. C.; Wang, D. H.; Ke, H.; Cao, Q. Q.; Huang, Y. L.; Luo, J. M.; Xu, J. L.; Hou, Y. H.; Du, Y. W.

2013-12-01

418

Predicted Disappearance of Saturation Hysteresis in Coarse Granular Media Based on Capillary and Gravity Scaling, and Experimental Tests  

NASA Astrophysics Data System (ADS)

Since the classic work of W. B. Haines (1930), hysteresis in the relation between matric (capillary) potential versus water content has been recognized as a basic aspect of interactions between water and variably saturated porous media. This lack of unique correspondence between potential and saturation has well-recognized consequences for equilibrium, flow, and transport. Although hysteresis in moisture characteristic relations has several causes, the existence of different pore-sizes within porous media (the "ink bottle" effect) is primary. This capillarity-dependent phenomenon has a grain-size limit imposed by the influence of gravity, and more generally by the relations between surface and body forces, and length scales. Above this limit, capillary hysteresis vanishes. The grain-size associated with vanishing of capillary hysteresis was predicted in two ways; first with a simple pore-size model, and second by Miller-Miller scaling. Both methods predict that hysteresis vanishes when characteristic grain-sizes exceed about 8 mm, when the water-air surface tension is 72 mN/m, and when the body force is due to ordinary gravity. More generally, capillary hysteresis is predicted to disappear when the Haines Number (dependent on grain-size, surface tension, the body force, density difference between immiscible fluids) exceeds 8. The predicted critical grain-size was experimentally supported through measurements of drainage and wetting curves of sands and gravels, with grain-sizes ranging from 0.2 up to 11 mm. We also consider effects of interfacial tension variation (surfactants), variation of the body force (centrifugal field), and capillarity associated with grain-surface roughness.

Tokunaga, T. K.; Olson, K. R.; Wan, J.

2002-12-01

419

Graphene drape minimizes the pinning and hysteresis of water drops on nanotextured rough surfaces.  

PubMed

Previous studies of the interaction of water with graphene-coated surfaces have been limited to flat (smooth) surfaces. Here we created a rough surface by nanopatterning and then draped the surface with a single-layer graphene sheet. We found that the ultrasheer graphene drape prevents the penetration of water into the textured surface thereby drastically reducing the contact angle hysteresis (which is a measure of frictional energy dissipation) and preventing the liquid contact line from getting pinned to the substrate. This has important technological implications since the main obstacle to the motion of liquid drops on rough surfaces is contact angle hysteresis and contact line pinning. Graphene drapes could therefore enable enhanced droplet mobility which is required in a wide range of applications in micro and nanofluidics. Compared to polymer coatings that could fill the cavities between the nano/micropores or significantly alter the roughness profile of the substrate, graphene provides the thinnest (i.e., most sheer) and most conformal drape that is imaginable. Despite its extreme thinness, the graphene drape is mechanically robust, chemically stable, and offers high flexibility and resilience which can enable it to reliably drape arbitrarily complex surface topologies. Graphene drapes may therefore provide a hitherto unavailable ability to tailor the dynamic wettability of surfaces for a variety of applications. PMID:23484526

Singh, Eklavya; Thomas, Abhay V; Mukherjee, Rahul; Mi, Xi; Houshmand, Farzad; Peles, Yoav; Shi, Yunfeng; Koratkar, Nikhil

2013-03-19

420

Memory-efficient architecture for hysteresis thresholding and object feature extraction.  

PubMed

Hysteresis thresholding is a method that offers enhanced object detection. Due to its recursive nature, it is time consuming and requires a lot of memory resources. This makes it avoided in streaming processors with limited memory. We propose two versions of a memory-efficient and fast architecture for hysteresis thresholding: a high-accuracy pixel-based architecture and a faster block-based one at the expense of some loss in the accuracy. Both designs couple thresholding with connected component analysis and feature extraction in a single pass over the image. Unlike queue-based techniques, the proposed scheme treats candidate pixels almost as foreground until objects complete; a decision is then made to keep or discard these pixels. This allows processing on the fly, thus avoiding additional passes for handling candidate pixels and extracting object features. Moreover, labels are reused so only one row of compact labels is buffered. Both architectures are implemented in MATLAB and VHDL. Simulation results on a set of real and synthetic images show that the execution speed can attain an average increase up to 24× for the pixel-based and 52× for the block-based when compared to state-of-the-art techniques. The memory requirements are also drastically reduced by about 99%. PMID:21521668

Najjar, Mayssaa A; Karlapudi, Swetha; Bayoumi, Magdy A

2011-04-25

421

What we can learn from the hysteresis properties of metal-bearing meteorites  

NASA Astrophysics Data System (ADS)

Metallic iron-nickel alloys are the main magnetic minerals in many meteorite groups, mostly in the form of kamacite, taenite and tetrataenite. We present here new room temperature hysteresis measurements on more than a hundred FeNi-bearing meteorite falls, mostly ordinary chondrites, as well as a synthesis of pre-existing data. Low temperature hysteresis measurements (down to 10 K) are also presented. These data are compared to other magnetic (magnetic susceptibility in particular) and petrographic parameters (intensity of thermal metamorphism, shock stage...). The bulk magnetic properties of these meteorites are primarily controlled by the relative proportion of the three above-mentioned minerals, and in particular the presence of tetrataenite. Discussion will focus on, but not be limited to: 1) The the elongated shape of metallic grains that is is revealed by the discrepancy between ferromagnetic susceptibility and saturation magnetization, whose ratio is too high for FeNi alloys; 2) The existence of a low temperature transition around 60 K; 3) The comparison between ordinary chondrites, carbonaceous chondrites, HED achondrites and lunar samples.

Gattacceca, J.; Rochette, P.; Suavet, C.; Uehara, M.

2010-12-01

422

Trapping and hysteresis in two-phase flow in porous media: A pore-network study  

NASA Astrophysics Data System (ADS)

Several models for two-phase flow in porous media identify trapping and connectivity of fluids as an important contribution to macroscale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are often based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are often not available for the trajectories, that is, the fate of the connectivity of the fluids while saturation changes. Here, using a quasi static pore-network model, supported by a set of pore-scale laboratory experiments, we study how the topology of the fluids changes during drainage and imbibition including first, main and scanning curves. We find a strong hysteretic behavior in the relationship between disconnected nonwetting fluid saturation and the wetting fluid saturation in a water-wet medium. The coalescence of the invading nonwetting phase with the existing disconnected nonwetting phase depends critically on the presence (or lack thereof) of connected nonwetting phase at the beginning of the drainage process as well as on the pore geometry. This dependence involves a mechanism we refer to as "reversible corner filling." This mechanism can also be seen in laboratory experiments in volcanic tuff. The impact of these pore-network model results on existing macroscopic models is discussed.

Joekar-Niasar, V.; Doster, F.; Armstrong, R. T.; Wildenschild, D.; Celia, M. A.

2013-07-01

423

Neurons with hysteresis from a network that can learn without any changes in synaptic connection strengths  

SciTech Connect

A neural network concept derived from an analogy between the immune system and the central nervous system is outlined. The theory is based on a neuron that is slightly more complicated than the conventional McCullogh-Pitts type of neuron, in that is exhibits hysteresis at the single cell level. This added complication is compensated by the fact that a network of such neurons is able to learn without the necessity for any changes in synaptic connection strengths. The learning occurs as a neural consequence of interactions between the network and its environment, with environmental stimuli moving the system around in an N-dimensional phase space, until a point in phase space is reached such that the system's responses are appropriate for dealing with the stimuli. Due to the hysteresis associated with each neuron, the system tends to stay in the region of phase space where it is located. The theory includes a role for sleep in learning. 18 refs., 2 figs.

Hoffmann, G.W.; Benson, M.W.

1986-01-01

424

Seasonal changes of free amino acids and thermal hysteresis in overwintering heteropteran insect, Pyrrhocoris apterus.  

PubMed

Overwintering adults of Pyrrhocoris apterus do not tolerate freezing of their body fluids and rely on a supercooling strategy and seasonal accumulation of polyols to survive at subzero body temperatures. We sampled the adults monthly in the field during the cold season 2008-2009 and found active thermal hysteresis factors (THFs) in hemolymph of winter-sampled adults. The hysteresis between the equilibrium melting and freezing points ranged from 0.18°C to 0.30°C. No signs of THFs activity were found in the autumn- and spring-sampled insects. The total free amino acid pool almost doubled during winter time. The sum concentrations of 27 free amino acids ranged between 35 and 40mM in whole body water and 40-45mM in hemolymph during December-February. Two amino acids, Pro and ?-Ala most significantly contributed to the seasonal increase, while Gln showed the most dramatic seasonal decrease. Moderate levels of amino acid accumulation in overwintering P. apterus suggest that they are by-products of protein degradation and pentose pathway activity during the state of metabolic suppression imposed by diapause and low body temperature. Potential colligative effects of accumulated amino acids, extending the supercooling capacity of overwintering P. apterus, are negligible. Non-colligative effects require further study. PMID:21729762

Koštál, Vladimír; Renault, David; Rozsypal, Jan

2011-06-27

425

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

426

The effect of body cooling on respiratory system mechanics and hysteresis in rats.  

PubMed

Literature reports and theoretical considerations suggest that body cooling may affect respiratory mechanics in vivo. To examine this hypothesis, healthy rats were studied using the end-inflation occlusion method under control conditions and after total body cooling. Respiratory mechanics parameters, hysteresis areas, the inspiratory work of breathing, and its elastic and resistive components, were calculated. After body cooling (mean rectal temperature from 36.6±0.25 to 32.1±0.26°C), the ohmic and the additional visco-elastic respiratory system resistances, the hysteresis, the total inspiratory work of breathing, and its resistive components, were all increased. No significant changes were detected for the static and dynamic respiratory system elastance mean values, and the related elastic component of the work of breathing. These data indicate that body cooling increases the mechanical inspiratory work of breathing by increasing the resistive pressures dissipation. This effect is evident even for limited temperature variations, and it is suggested that it may occur in the event of accidental or therapeutic hypothermia. PMID:23827852

Rubini, Alessandro; El-Mazloum, Dania; Morra, Francesco; Bosco, Gerardo

2013-07-01

427

The improved hysteresis characteristics of flux-lock type SFCL using third winding  

NASA Astrophysics Data System (ADS)

In this paper, we showed that the third winding of the flux-lock type high-Tc superconducting fault current limiter (HTSC-FCL) could be operated as the damping coil to suppress the saturation of the iron core during a fault period. This third winding of the HTSC-FCL was installed to apply the magnetic field into HTSC element simultaneously after a fault happened. To confirm it, the hysteresis characteristics of an iron core of the flux-lock type HTSC-FCL were investigated from the equivalent circuit of a saturable transformer including the nonlinear magnetizing characteristic. Due to the magnetic coupled structure of the flux-lock reactor together with the third winding, the iron core of the flux-lock type HTSC-FCL could be restrained from saturation during a fault period. Through the analysis for the fault current limiting characteristics and the hysteresis ones obtained from the experimental results, the fault current limiting level as well as the saturation of the iron core of the flux-lock type HTSC-FCL with the third winding could be more improved than that of the flux-lock type HTSC-FCL without the third winding.

Lim, Sung-Hun; Choi, Hyo-Sang; Han, Byoung-Sung

2004-07-01

428

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

429

Nanosecond-range imprint and retention characterized from polarization-voltage hysteresis loops in insulating or leaky ferroelectric thin films  

NASA Astrophysics Data System (ADS)

We transferred ferroelectric domain switching currents under pulses into polarization-voltage (P-V) hysteresis loops. With this transformation, it is possible to derive the remanent polarization and coercive voltage from domain switching currents after the shortest imprint and retention time of 35 ns. After the separation of film leakage current from domain switching current, we measured the P-V hysteresis loop in a semiconducting BiFeO3 leaky thin film, where the apparent coercive field highly reaches 320 kV/cm2, suggestive of a different domain switching mechanism from other insulators. This technique facilitates nanosecond-range measurements of both ferroelectric capacitive and resistive memories.

Jiang, A. Q.; Liu, X. B.; Zhang, Q.

2011-10-01

430

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

431

A 4-D chaotic oscillator with a hysteresis 2-port VCCS: the first example of chaotic oscillators consisting of 2-port VCCSs and capacitors  

Microsoft Academic Search

This paper studies the synthesis of chaotic oscillators using 2-port VCCSs and capacitors. As a first step, we design a 4-D hysteresis chaotic oscillator using one linear 2-port VCCS, one hysteresis 2-port VCCS and two capacitors. In the circuit, we have confirmed theoretically that a simple periodic attractor changes into quad screw chaotic attractor as influence of the nonlinearity decreases

M. Kataoka; T. Saito

1999-01-01

432

Hysteresis Phenomenon and Huge Isotope Effect in Hydrogenation Cycles of Some Cerium-Containing LaNi sub 5 -Type Compounds.  

National Technical Information Service (NTIS)

The huge hysteresis effect and the isotope effect, two effects that accompany the hydrogen absorbing process of cerium containing LaHi sub 5 -type compound were studied. The hysteresis effect was studied on compounds of the type (Lasub(0.5)Cesub(0.5))Nisu...

D. Dayan

1982-01-01

433

Diodelike and resistive hysteresis behavior of heterolayered BiFeO3/ZnO ferroelectric thin films  

NASA Astrophysics Data System (ADS)

BiFeO3/ZnO, ZnO/BiFeO3, BiFeO3/ZnO/BiFeO3, and ZnO/BiFeO3/ZnO thin film heterostructures were deposited on SrRuO3/Pt(111)/TiO2/SiO2/Si(100) substrates by off-axis radio frequency sputtering. Their diodelike and resistive hysteresis behavior are dependent on the combination sequence of the constituent layers in the heterostructures. Both the diodelike and resistive hysteresis behavior were clearly observed in BiFeO3/ZnO and ZnO/BiFeO3. The phenomena became more apparent with rising temperature. The behavior arises from the interface formed between BiFeO3 and ZnO. As expected, the diodelike and resistive hysteresis behavior are weakened and almost disappeared in the case of BiFeO3/ZnO/BiFeO3 and ZnO/BiFeO3/ZnO, where the two interfaces are equal and opposite to each other. The interface-limited Fowler-Nordheim tunneling in the high electric field region is demonstrated to involve in the formation of resistive hysteresis.

Wu, Jiagang; Wang, John

2010-11-01

434

Reduction of boiling thermal hysteresis in immersed electronics cooling on micro-configured graphite-metal conposite surfaces  

Microsoft Academic Search

It is known that hysteresis is an important and unique dynamic characteristics in two-phase systems in motion with or without rotation. In pool boiling which generates vapor phase, the system is set in motion due to a pumping action near the heating surface caused by the departure of bubbles whose space is replaced by the surrounding liquid body. However, its

Wen-Jei Yang; Nengli Zhang; D. F. Chao; T. Shuichi

2010-01-01

435

The Unsteady Pressure Field in a High Specific Speed Centrifugal Pump Impeller—Part II: Transient Hysteresis in the Characteristic  

Microsoft Academic Search

vS 5 1.7) centrifugal pump characteristic was experimentally evaluated. A hypothesis for recirculation zones and prerotation as power dissipaters is proposed for explaining the discrepancy in the pressure and shaft power hysteresis. The experimental investigation was performed in both the rotating and stationary frame. In the rotating frame 25 miniature pressure transducers mounted in an impeller blade passage were sampled

Kevin A. Kaupert; Thomas Staubli

1999-01-01

436

A Comparison Between Different Methods of Modeling Hysteresis Loop in Three-Phase Three-Legged Transformers  

Microsoft Academic Search

Regarding the transformer modeling, many numerical methods have been applied to simulate the nonlinearity of transformer core. In this paper the nonlinear model of a three-phase three-legged transformer has been implemented in MATLAB environment. The comparison between the MATLAB computed results and the results from source paper confirms the correct implementation of the model. Also hysteresis loop of this transformer

S. R. Mosayyebi; A. Jalilian

2006-01-01

437

Hysteresis and magnetostriction of TbxDyyHo1-x-yFe1.95 [112] dendritic rods  

NASA Astrophysics Data System (ADS)

The magnetization and magnetostriction of a variety of 3/16-in.-diam Laves phase rods of TbxDyyHo1-x-yFe1.95 grown in the form of [112] oriented dendritic compounds were measured as a function of applied magnetic field -3000hysteresis with only slightly lower magnetostriction. The Ho concentration was kept relatively small (<=0.3) to avoid a substantial decrease in the magnetostriction, while the ratio of x and y was chosen to examine alloys spanning the line of minimum magnetic anisotropy. Most of the compositions have twice the Ho content of the previous study. As expected, alloys with higher Ho concentrations showed narrower hysteresis curves. The data shows that at 22 MPa, the Tb0.28Dy0.57Ho0.15Fe1.95 composition has a minimal (3%) loss of magnetostriction, while the hysteresis width decreased by 15%. Between 15% and 20% Ho content, the magnetostriction drops abruptly. For alloys with a fixed Ho concentration, the strain showed a peak near the expected anisotropy minimum, but the hysteresis width always increased with increasing Tb content.

Wun-Fogle, M.; Restorff, J. B.; Clark, A. E.

1999-04-01

438

Effects of hysteresis on redistribution of soil moisture and deep percolation at continuous and pulse drip irrigation  

Microsoft Academic Search

The infiltration and redistribution of soil moisture under surface drip irrigation considering hysteresis were investigated in two soils (loamy sand and silt loam) of different texture. The effect of continuous versus intermittent application of 1, 2 and 4l\\/h to the soils was evaluated in terms of wetting front advance patterns and deep percolation under the root zone. For this purpose,

S. Elmaloglou; E. Diamantopoulos

2009-01-01

439

Droplet combustion in presence of airstream oscillation: Mechanisms of enhancement and hysteresis of burning rate in microgravity at elevated pressure  

Microsoft Academic Search

The enhancement and hysteresis behavior of the burning rate of single droplet combustion in the presence of airstream oscillation observed in previously performed microgravity experiments at elevated pressure up to 1.0MPa were numerically investigated. Excellent agreement with the experimental results was obtained and the mechanisms of these phenomena were examined based on precise numerical data on instantaneous droplet diameter variations

Mehdi Jangi; Hideaki Kobayashi

2010-01-01

440

Intrinsic doping and gate hysteresis in graphene field effect devices fabricated on SiO2 substrates.  

PubMed

We have studied the intrinsic doping level and gate hysteresis of graphene-based field effect transistors (FETs) fabricated over Si/SiO(2) substrates. It was found that the high p-doping level of graphene in some as-prepared devices can be reversed by vacuum degassing at room temperature or above depending on the degree of hydrophobicity and/or hydration of the underlying SiO(2) substrate. Charge neutrality point (CNP) hysteresis, consisting of the shift of the charge neutrality point (or Dirac peak) upon reversal of the gate voltage sweep direction, was also greatly reduced upon vacuum degassing. However, another type of hysteresis, consisting of the change in the transconductance upon reversal of the gate voltage sweep direction, persists even after long-term vacuum annealing at 200?°C, when SiO(2) surface-bound water is expected to be desorbed. We propose a mechanism for this transconductance hysteresis that involves water-related defects, formed during the hydration of the near-surface silanol groups in the bulk SiO(2), that can act as electron traps. PMID:21386504

Joshi, P; Romero, H E; Neal, A T; Toutam, V K; Tadigadapa, S A

2010-08-04

441

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

442

Finding knight's tours on an M×N chessboard with O(MN) hysteresis McCulloch-Pitts neurons  

Microsoft Academic Search

How can a knight be moved on a chessboard so that the knight visits each square once and only once and goes back to the starting square? The earliest serious attempt to find a knight's tour on the chessboard was made by L. Euler in 1759 [1]. In this correspondence, a parallel algorithm based on the hysteresis McCulloch-Pitts neurons is

Kuo-Chun Lee; Yoshiyasu Takefuji

1994-01-01

443

Simple models for dynamic hysteresis loop calculations of magnetic single-domain nanoparticles: Application to magnetic hyperthermia optimization  

NASA Astrophysics Data System (ADS)

To optimize the heating properties of magnetic nanoparticles (MNPs) in magnetic hyperthermia applications, it is necessary to calculate the area of their hysteresis loops in an alternating magnetic field. The separation between ``relaxation losses'' and ``hysteresis losses'' presented in several articles is artificial and criticized here. The three types of theories suitable for describing hysteresis loops of MNPs are presented and compared to numerical simulations: equilibrium functions, Stoner-Wohlfarth model based theories (SWMBTs), and a linear response theory (LRT) using the Néel-Brown relaxation time. The configuration where the easy axis of the MNPs is aligned with respect to the magnetic field and the configuration of a random orientation of the easy axis are both studied. Suitable formulas to calculate the hysteresis areas of major cycles are deduced from SWMBTs and from numerical simulations; the domain of validity of the analytical formula is explicitly studied. In the case of minor cycles, the hysteresis area calculations are based on the LRT. A perfect agreement between the LRT and numerical simulations of hysteresis loops is obtained. The domain of validity of the LRT is explicitly studied. Formulas are proposed to calculate the hysteresis area at low field that are valid for any anisotropy of the MNP. The magnetic field dependence of the area is studied using numerical simulations: it follows power laws with a large range of exponents. Then analytical expressions derived from the LRT and SWMBTs are used in their domains of validity for a theoretical study of magnetic hyperthermia. It is shown that LRT is only pertinent for MNPs with strong anisotropy and that SWMBTs should be used for weakly anisotropic MNPs. The optimum volume of MNPs for magnetic hyperthermia is derived as a function of material and experimental parameters. Formulas are proposed to allow to the calculation of the optimum volume for any anisotropy. The maximum achievable specific absorption rate (SAR) is calculated as a function of the MNP anisotropy. It is shown that an optimum anisotropy increases the SAR and reduces the detrimental effects of the size distribution of the MNPs. The optimum anisotropy is simple to calculate; it depends only on the magnetic field used in the hyperthermia experiments and the MNP magnetization. The theoretical optimum parameters are compared to those of several magnetic materials. A brief review of experimental results as well as a method to analyze them is proposed. This study helps in the determination of suitable and unsuitable materials for magnetic hyperthermia and provides accurate formulas to analyze experimental data. It is also aimed at providing a better understanding of magnetic hyperthermia to researchers working on this subject.

Carrey, J.; Mehdaoui, B.; Respaud, M.

2011-04-01

444

Hysteresis, Switching and Anomalous Behaviour of a Quartz Tuning Fork in Superfluid 4He  

NASA Astrophysics Data System (ADS)

We have been studying the behaviour of commercial quartz tuning forks immersed in superfluid 4He and driven at resonance. For one of the forks we have observed hysteresis and switching between linear and non-linear damping regimes at temperatures below 10 mK. We associate linear damping with pure potential flow around the prongs of the fork, and non-linear damping with the production of vortex lines in a turbulent regime. At appropriate prong velocities, we have observed metastability of both the linear and the turbulent flow states, and a region of intermittency where the flow switched back and forth between each state. For the same fork, we have also observed anomalous behaviour in the linear regime, with large excursions in both damping, resonant frequency, and the tip velocity as a function of driving force.

Bradley, D. I.; Fear, M. J.; Fisher, S. N.; Guénault, A. M.; Haley, R. P.; Lawson, C. R.; Pickett, G. R.; Schanen, R.; Tsepelin, V.; Wheatland, L. A.

2013-10-01

445

Amplitude and frequency dependence of hysteresis loss in a magnet-superconductor levitation system  

SciTech Connect

Using an electromagnetically controlled mechanical pendulum, we measured the energy loss for different amplitudes in a magnetic levitation system that contained high temperature superconductors (HTSs). Two procedures were followed to measure losses at 77 K for frequencies of 93.8 mHz to 80 Hz. In the first procedure, the distance between the permanent magnet and the HTS levitator was the same as that during (field) cooling. In the second procedure, the magnet was lowered (after cooling) closer to the HTS levitator before the measurements were performed. The experimental data show that these two procedures give essentially the same results at the same distance despite different cooling (and magnetization) histories for melt-textured YBaCuO levitators, and the frequency-independent energy loss is a power-law function of amplitude. We attribute the energy loss to magnetic hysteresis in the superconductor. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Yang, Z.J.; Hull, J.R.; Mulcahy, T.M. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Rossing, T.D. [Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)

1995-08-01

446

Hysteresis in transition between individual and collective behavior in suspension of swimming bacteria  

NASA Astrophysics Data System (ADS)

We present a new method for control of motility and tumbling rate of swimming bacteria Bacillus Subtilis via precise and rapid control of temperature of the bacterial suspension. Transitions between individual and collective behaviors in a response to cyclical temperature change in a range of temperatures between 5C and 35C with the rates from 0.1C/s to 1C/s were investigated. Temperature decrease typically results in a decrease of bacterial motility while preserving low tumbling rates. The temperature increase above 20C triggers a ``heat shock'': a significant jump in tumbling rate resulting in temporal decrease of the average swimming speed and termination of collective motion. At temperatures below 20C due to relative low tumbling rates we discovered a hysteresis in the transition between individual and collective swimming: velocity correlation length vs. average swimming speed of bacteria exhibits hysteric behavior.

Sokolov, Andrey; Aranson, Igor

2013-03-01

447

Characterization upon electrical hysteresis and thermal diffusion of TiAl3O x dielectric film  

NASA Astrophysics Data System (ADS)

In this paper, we have investigated the electrical properties of TiAl3O x film as electrical gate insulator deposited by pulsed laser deposition and presented a simple method to describe the thermal diffusion behaviors of metal atoms at TiAl3O x /Si interfacial region in detail. The TiAl3O x films show obvious electrical hysteresis by the capacitance-voltage measurements after post-annealing treatment. By virtue of the diffusion models composed of TiAl3O x film and silicon, the diffusion coefficient and the diffusion activation energy of the Ti and Al atoms are extracted. It is valuable to further investigate the pseudobinary oxide system in practice. PACS: 77.55.-g; 81.15.Fg; 81.40.Gh.

Shi, Lei; Liu, Zhiguo

2011-10-01

448

CMR of Co/Cu multilayers with reduced hysteresis and low-field response  

SciTech Connect

We present the results of a systematic study on optimization of the giant magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for copper layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t(1)Co) and thin (t(2)Co) layers have been prepared in the from of [Cot(1)CoA/Cu20A/Cot(2)CoA/Cu20A]15. We have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t(2)Co and has disappeared when t(2)Co<4.5A. We have obtained an optimal GMR response with a field sensitivity of 0. 013%/Oe over a field region of -60 Oe centered at -50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications.

Mao, M.; Gibbons, M.; Law, B.; Grabner, F.; Veron, S.; Cerjan, C.

1997-02-01

449

Microscopic pattern of ice crystal growth in the presence of thermal hysteresis proteins  

SciTech Connect

This study examines the effect of thermal hysteresis proteins (THPs) from the winter flounder (Psuedopleuronectes americanus) on the ice-water interface morphology during freezing of aqueous solutions. Experiments were performed using a directional solidification stage, and the development of the two-phase interface was observed through a microscope and recorded by a video system. Unusual ice crystal morphologies were observed, including faceted ice crystal growth along the (1100) crystal plane; spicular or needlelike growth in the (1010) direction; and growth parallel to the c-axis, (0001), consisting of incorporated liquid inclusions bounded by hexagonal prism faces. The observed crystallographic structures can be explained as an effect of the interaction between the THPs and the primary prism faces of ice crystals. This results in an increase in the Gibbs free energy of these planes, followed by ice growth into the supercooled liquid adjacent to these faces.

Coger, R.; Rubinsky, B. (Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering); Fletcher, G. (Memorial Univ. of Newfoundland, St. John's, Newfoundland (Canada))

1994-08-01

450

Global analysis of a model pulsing drug delivery oscillator based on chemomechanical feedback with hysteresis  

NASA Astrophysics Data System (ADS)

A simple model for an autonomous pulsing drug delivery system was previously introduced. This model involves negative feedback action, with hysteresis, of an enzyme on the permeability of a membrane through which substrate, at constant external concentration, must diffuse to reach the enzyme. The qualitative dynamics of this model permit, depending on system parameters and external driving substrate concentration, two separate single steady state, double steady state, and permanently alternating (oscillatory) behaviors. The present contribution is concerned with rigorous proofs regarding the global stability of steady states when permanent alternation is precluded, and the existence and globally asymptotic stability of a limit cycle in the permanently alternating case. Also, we prove that more restrictive but often realistic conditions on the system parameters imply limitations on the number of alternations the system can undergo before reaching steady state.

Li, Bingtuan; Siegel, Ronald A.

2000-09-01

451

Defect-related hysteresis in nanotube-based nano-electromechanical systems  

PubMed Central

The electronic properties of multi-walled carbon nanotubes (MWCNTs) depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems (NEMS). In this article, we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes (DWCNTs) and their role in the response of the host systems under inter-tube displacement. Key defect-related effects, namely, sudden energy changes and hysteresis, are identified, and their relevance to a host of MWCNT-based NEMS is highlighted. The results also demonstrate the dependence of these effects on defect clustering and chirality of DWCNT shells.

2011-01-01

452

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

453

Curvature-dependent metastability of the solid phase and the freezing-melting hysteresis in pores.  

PubMed

We recapitulate and generalize the concept of the freezing-melting hysteresis that attributes this phenomenon to a free-energy barrier between metastable and stable states of pore-filling material. In a phenomenological description, we show that under commonly encountered conditions, this renders the freezing-point depression DeltaTf defined by the surface-to-volume ratio S/V, whereas the melting-point depression DeltaTm, by the mean curvature kappa of the pore surface, with DeltaTm/DeltaTf =2kappa(V/S). Employing 1H NMR cryoporometry, we experimentally demonstrate the linear correlation between DeltaTm and DeltaTf for several liquids with different DeltaTf,m imbibed in controlled pore glasses. The results compare favorably to the morphological properties of the glasses determined by other techniques. Our findings suggest a simple method for analyzing the pore morphology from the observed phase transition temperatures. PMID:16486162

Petrov, Oleg; Furó, István

2006-01-31

454

Graphene on a hydrophobic substrate: doping reduction and hysteresis suppression under ambient conditions.  

PubMed

The intrinsic doping level of graphene prepared by mechanical exfoliation and standard lithography procedures on thermally oxidized silicon varies significantly and seems to depend strongly on processing details and the substrate morphology. Moreover, transport properties of such graphene devices suffer from hysteretic behavior under ambient conditions. The hysteresis presumably originates from dipolar adsorbates on the substrate or graphene surface. Here, we demonstrate that it is possible to reliably obtain low intrinsic doping levels and to strongly suppress hysteretic behavior even in ambient air by depositing graphene on top of a thin, hydrophobic self-assembled layer of hexamethyldisilazane (HMDS). The HMDS serves as a reproducible template that prevents the adsorption of dipolar substances. It may also screen the influence of substrate deficiencies. PMID:20218633

Lafkioti, Myrsini; Krauss, Benjamin; Lohmann, Timm; Zschieschang, Ute; Klauk, Hagen; Klitzing, Klaus V; Smet, Jurgen H

2010-04-14

455

Spectral properties of the Preisach hysteresis model with random input. I. General results  

NASA Astrophysics Data System (ADS)

We derive exact results for the spectral density S(?) of the output of the Preisach model, a standard model for complex, nonlocal hysteresis. We obtain general results for uncorrelated input signals with arbitrary input and Preisach densities. It is shown analytically that uncorrelated input signals are transformed into output exhibiting long-time correlations. For the simplest example of uniform input and Preisach distributions we prove that correlations decay asymptotically with a t-3 power law corresponding to a logarithmic low frequency divergence of the second derivative of the spectrum S(?) . A simpler expression for symmetric Preisach models is also obtained, which is discussed in detail in Part II, showing that long-time tails or even 1/f noise are general features of this class of models.

Radons, Günter

2008-06-01

456

Magnetic Nonuniformity and Thermal Hysteresis of Magnetism in a Manganite Thin Film  

NASA Astrophysics Data System (ADS)

We measured the chemical and magnetic depth profiles of a single crystalline (La1-xPr?x)1-yCayMnO3-? (x=0.52±0.05, y=0.23±0.04, ?=0.14±0.10) film grown on a NdGaO3 substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy, and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first-order ferromagnetic transition at low temperatures.

Singh, Surendra; Fitzsimmons, M. R.; Lookman, T.; Thompson, J. D.; Jeen, H.; Biswas, A.; Roldan, M. A.; Varela, M.

2012-02-01

457

Defect-related hysteresis in nanotube-based nano-electromechanical systems.  

PubMed

The electronic properties of multi-walled carbon nanotubes (MWCNTs) depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems (NEMS). In this article, we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes (DWCNTs) and their role in the response of the host systems under inter-tube displacement. Key defect-related effects, namely, sudden energy changes and hysteresis, are identified, and their relevance to a host of MWCNT-based NEMS is highlighted. The results also demonstrate the dependence of these effects on defect clustering and chirality of DWCNT shells. PMID:21711767

Tsetseris, Leonidas; Pantelides, Sokrates T

2011-03-22

458

Defect-related hysteresis in nanotube-based nano-electromechanical systems  

NASA Astrophysics Data System (ADS)

The electronic properties of multi-walled carbon nanotubes (MWCNTs) depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems (NEMS). In this article, we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes (DWCNTs) and their role in the response of the host systems under inter-tube displacement. Key defect-related effects, namely, sudden energy changes and hysteresis, are identified, and their relevance to a host of MWCNT-based NEMS is highlighted. The results also demonstrate the dependence of these effects on defect clustering and chirality of DWCNT shells.

Tsetseris, Leonidas; Pantelides, Sokrates T.

2011-12-01

459

Recruitability of the lung estimated by the pressure volume curve hysteresis in ARDS patients  

Microsoft Academic Search

Objective  To assess the hysteresis of the pressure–volume curve (PV curve) as to estimate, easily and at the bedside, the recruitability\\u000a of the lung in ARDS patients.\\u000a \\u000a \\u000a \\u000a Design  Prospective study.\\u000a \\u000a \\u000a \\u000a Setting  Twelve medico-surgical ICU beds of a general hospital.\\u000a \\u000a \\u000a \\u000a Patients  Twenty-six patients within the first 24 h from meeting ARDS criteria.\\u000a \\u000a \\u000a \\u000a Intervention  A Quasi-static inflation and deflation PV curve from 0 to 40 cmH2O and a 40 cmH2O

Didier Demory; Jean-Michel Arnal; Marc Wysocki; Stéphane Donati; Isabelle Granier; Gaëlle Corno; Jacques Durand-Gasselin

2008-01-01

460

Nanomechanical Detection of Magnetic Hysteresis of a Single-crystal Yttrium Iron Garnet Micromagnetic Disk  

NASA Astrophysics Data System (ADS)

A micromagnetic disk was milled from a monocrystalline yttrium iron garnet film using a focused ion beam and micromanipulated onto a nanoscale torsional resonator. Nanomechanical torque magnetometry results show a unipolar magnetic hysteresis characteristic of a magnetic vortex state. Landau-Lifshitz-Gilbert-based micromagnetic simulations of the disk show a rich, flux-enclosed, three-dimensional domain structure. On the top and bottom faces of the disk, a skewed vortex state exists with a very small core. The core region extends through the thickness of the disk with a smooth variation in core diameter reaching a maximum along the midplane of the disk. The single crystalline nature of the disk lends to an observed absence of Barkhausen-like steps in the magnetization-versus-field curves, qualitatively different in comparison to the magnetometry results of an individual polycrystalline permalloy microdisk. Prospects for the mechanical detection of spin dynamical modes in these structures will also be discussed.

Losby, Joseph; Diao, Zhu; Burgess, Jacob; Compton, Shawn; Fani Sani, Fatemeh; Firdous, Tayyaba; Vick, Douglas; Belov, Miro; Hiebert, Wayne; Freeman, Mark

2013-03-01

461

Theory of sorption hysteresis in nanoporous solids: Part I. Snap-through instabilities  

NASA Astrophysics Data System (ADS)

The sorption-desorption hysteresis observed in many nanoporous solids, at vapor pressures low enough for the liquid (capillary) phase of the adsorbate to be absent, has long been vaguely attributed to some sort of ‘pore collapse’. However, the pore collapse has never been documented experimentally and explained mathematically. The present work takes an analytical approach to account for discrete molecular forces in the nanopore fluid and proposes two related mechanisms that can explain the hysteresis at low vapor pressure without assuming any pore collapse nor partial damage to the nanopore structure. The first mechanism, presented in Part I, consists of a series of snap-through instabilities during the filling or emptying of non-uniform nanopores or nanoscale asperities. The instabilities are caused by non-uniqueness in the misfit disjoining pressures engendered by a difference between the nanopore width and an integer multiple of the thickness of a monomolecular adsorption layer. The wider the pore, the weaker the mechanism, and it ceases to operate for pores wider than about 3 nm. The second mechanism, presented in Part II, consists of molecular coalescence, or capillary condensation, within a partially filled surface, nanopore or nanopore network. This general thermodynamic instability is driven by attractive intermolecular forces within the adsorbate and forms the basis for developing a unified theory of both mechanisms. The ultimate goals of the theory are to predict the fluid transport in nanoporous solids from microscopic first principles, determine the pore size distribution and internal surface area from sorption tests, and provide a way to calculate the disjoining pressures in filled nanopores, which play an important role in the theory of creep and shrinkage.

Bažant, Zden?k P.; Bazant, Martin Z.

2012-09-01

462

Communities, clustering phase transitions, and hysteresis: pitfalls in constructing network ensembles.  

PubMed

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

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

2010-04-27

463

Modeling the Relationship Between Neutron Counting Rates and Sunspot Numbers Using the Hysteresis Effect  

NASA Astrophysics Data System (ADS)

Several studies show that temporal variations in the Galactic cosmic ray (GCR) intensity display a distinct 11-year periodicity due to solar modulation of the galactic cosmic rays in the heliosphere. The 11-year periodicity of GCRs is inversely proportional to, but out of phase with, the 11-year solar cycle, implying that there is a time lag between actual solar cycle and the GCR intensity, which is known as the hysteresis effect. In this study, we use the hysteresis effect to model the relationship between neutron counting rates (NCRs), an indicator of the GCR intensity, and sunspot numbers (SSNs) over the period that covers the last four solar cycles (20, 21, 22, and 23). Both linear and ellipse models were applied to SSNs during odd and even cycles in order to calculate temporal variations of NCRs. We find that ellipse modeling provides higher correlation coefficients for odd cycles compared to linear models, e.g. 0.97, 0.97, 0.92, and 0.97 compared to 0.69, 0.72, 0.53, and 0.68 for data from McMurdo, Swarthmore, South Pole, and Thule neutron monitors, respectively, during solar cycle 21 with overall improvement of 31 % for odd cycles. When combined to a continuous model, the better correlation observed for the odd cycles increases the overall correlation between observed and modeled NCRs. The new empirical model therefore provides a better representation of the relationship between NCRs and SSNs. A major goal of the ongoing research is to use the new non-linear empirical model to reconstruct SSNs on annual time scales prior to 1610, where we do not have observational records of SSNs, based on changes in NCRs reconstructed from 10Be in ice cores.

Inceoglu, F.; Knudsen, M. F.; Karoff, C.; Olsen, J.

2013-09-01

464

Hysteresis and two-dimensional nonlinear wave propagation in Berea Sandstone  

NASA Astrophysics Data System (ADS)

We have further developed a two-dimensional endochronic constitutive model applicable to rock in the intermediate strain regime, i.e., approximately 10-6 to 10-3, where nonlinear losses, pulse distortion, and harmonic distortions have been documented in the laboratory. An accurate and efficient computation algorithm has been established and used to fit a set of triaxial laboratory data on Berea Sandstone, obtained by G. N. Boitnott of New England Research, Inc., including nonlinear hysteresis for both hydrostatic compression and shear deformation. The constitutive model has been incorporated into a two-dimensional pseudospectral scheme for simulating nonlinear wave propagation. We compare our numerical pseudospectral scheme with the perturbation solutions to nonlinearly elastic plane wave propagation and find that the two solutions are in close agreement. Applying the numerical scheme to the endochronic constitutive model for Berea Sandstone, we find the following results, which confirm and extend previous results obtained with a one-dimensional model: (1) nonlinear propagation from a monochromatic source excites odd harmonics of the source frequency, (2) the interaction of two monochromatic wave fields leads to energy transfer to other bands corresponding to various combinations of the two source frequencies, (3) amplitudes of the harmonics change with distance and show a trade-off between nonlinearity, intrinsic attenuation (hysteresis), and geometrical spreading, (4) for a broadband pressure source, energy is transferred from the principal band to a higher band at the expense of the components at intermediate frequencies; this is diagnostic of nonlinear interactions, and (5) the harmonic amplitude and energy transfer increase nonlinearly with strain amplitude; i.e., higher strain levels lead to higher energy exchange. These simulations of harmonic generation, interaction, and band expansion, based on a model developed from quasistatic experimental observations, agree with dynamic experimental observations.

Xu, Heming; Day, Steven M.; Minster, Jean-Bernard H.

2000-03-01

465

Infiltration of Liquid Droplets Into Porous Media: Effects of Dynamic Contact Angle and Contact Angle Hysteresis  

NASA Astrophysics Data System (ADS)

Infiltration of liquid droplets into dry porous media occurs when rain drops fall onto soil, when accidentally spilling organic liquid (e.g., gasoline and chlorinated solvents) onto ground, or when aerosol pesticides are not intercepted by the vegetation and then released to soils. If harmful chemicals are released from the droplet into the atmosphere through evaporation, it is important to know the time of infiltration. We developed a theory for infiltration, which accounts for a general model for the dynamic contact angle between the droplet and the porous medium as well as contact angle hysteresis. Our theory assumes the droplet to have the shape of a spherical cap and the pressure within the droplet to be uniform. The theory shows that droplet infiltration involves three phases due to contact angle hysteresis: (1) an increasing drawing area (IDA) phase during which the interface between the droplet and the porous medium increases, (2) a constant drawing area (CDA) phase during which the contact line of the droplet remains pinned, and (3) a decreasing drawing area (DDA) phase. We find that infiltration always consists of a cascade process formed by the IDA, CDA, and DDA phases, where the entire process may begin or end in any of the three phases. The entire process is formulated with four nondimensional parameters: three contact angles (initial, advancing, and receding) and a porous permeability parameter that depends on porous medium geometry. The total time of infiltration and the time dependence of drawing area are critically affected by the occurrence of the IDA, CDA, and DDA phases as well as by the permeability. In general, the IDA and DDA phases are described by integro-differential equations. With ordinary differential equations (ODEs), we are able to approximate the IDA phase and to describe exactly infiltration processes that starts out with the CDA or DDA phase.

Hilpert, M.

2008-12-01

466

Drift and Hysteresis Effects on AlN/SiO2 Gate pH Ion-Sensitive Field-Effect Transistor  

NASA Astrophysics Data System (ADS)

The nonideal and unstable factors of AlN-based ion-sensitive field-effect transistor (ISFET) devices including the drift and hysteresis effects have been investigated in this study. The drift and hysteresis of AlN-bas