Note: This page contains sample records for the topic p-e hysteresis loop 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

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

2

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

21

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

22

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

23

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

24

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

25

Simulations of magnetic hysteresis loops for dual layer recording media  

NASA Astrophysics Data System (ADS)

A Kinetic Monte-Carlo algorithm is applied to examine MH loops of dual-layer magnetic recording media at finite temperature and long time scales associated with typical experimental measurements. In contrast with standard micromagnetic simulations, which are limited to the ns-?s time regime, our approach allows for the direct calculation of magnetic configurations over periods from minutes to years. The model is used to fit anisotropy and coupling parameters to experimental data on exchange-coupled composite media which are shown to deviate significantly from standard micromagnetic results. Sensitivities of the loops to anisotropy, inter-layer exchange coupling, temperature, and sweep rate are examined.

Fal, T. J.; Plumer, M. L.; Whitehead, J. P.; Mercer, J. I.; van Ek, J.; Srinivasan, K.

2013-05-01

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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

39

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

40

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

41

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

42

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

43

Comparison of hysteresis loops from giant magnetoresistance and magnetometry for perpendicular-current exchange-biased spin valves  

Microsoft Academic Search

We compare for permalloy (Py)\\/Cu\\/Py or Py\\/Ag\\/Py exchange-biased spin valves, hysteresis loops of: (1) giant magnetoresistance (GMR) with current perpendicular to the layer planes (CPP-MR), and (2) magnetization M measured for the same portion of the sample used to measure the CPP-MR. As expected, the two kinds of loops are mostly very similar. There are, however, some slight differences, the

S. D. Steenwyk; S. Y. Hsu; R. Loloee; J. Bass; W. P. Pratt

1997-01-01

44

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

45

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

46

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

47

Asymmetric hysteresis loops and its dependence on magnetic anisotropy in exchange biased Co/CoO core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

The origin of asymmetry in field cooled (FC) hysteresis loops exhibiting exchange bias (EB) is investigated by studying the static and dynamic magnetic properties of core-shell Co/CoO nanoparticles. Two distinct freezing temperatures coresponding to the core (Tf-cr ~ 190 K) and the shell moments (Tf-sh ~ 95 K) are obtained from the energy barrier distribution. The FC loops are symmetric in the temperature range Tf-sh <= T <= Tf-cr, however, asymmetry in hysteresis is observed immediately below Tf-sh. These intriguing features are also probed by radio frequency transverse susceptibility (TS) experiments. We show that the first anisotropy fields obtained from the demagnetization and return curves of field cooled TS measurement, shift along the negative field axis and strikingly resemble the temperature dependence of EB. Field cooled TS measurements reveal the effect of competing Zeeman and anisotropy energy above and below Tf-sh to account for the development of asymmetry. Our study indicates that asymmetry in FC hysteresis loops is intrinsic to core-shell nanoparticles and develops only below the freezing temperature of the shell due to enhanced magnetic anisotropy.

Chandra, Sayan; Khurshid, Hafsa; Phan, Manh-Huong; Srikanth, Hariharan

2012-12-01

48

Origin of anomalous hysteresis loops induced by femtosecond laser pulses in GdFeCo amorphous films  

NASA Astrophysics Data System (ADS)

A controllable pump-pulse-number magneto-optical Kerr technique combined with an initializing field scanning approach is developed to eliminate and identify memory and accumulation effects, respectively, from external field history and multiple pulse excitations. A series of anomalous loops of GdFeCo films are measured for different amount of pump pulses using this technique, revealing that serious memory and accumulation effects exist in continuous-pulse-pumped anomalous hysteresis loops which show illusory information of hot coercivity and degree of magnetization reversal. Single-pulse-induced anomalous loop reveals that the hot coercivity shown by continuous-pulse-pumped anomalous loops is not the minimum external field that drives real magneto-optical recording.

Xu, Chudong; Chen, Zhifeng; Chen, Daxin; Zhou, Shiming; Lai, Tianshu

2010-03-01

49

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

SciTech Connect

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

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

2012-03-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

51

Spectral properties of the Preisach hysteresis model with random input. II. Universality classes for symmetric elementary loops  

NASA Astrophysics Data System (ADS)

The Preisach model with symmetric elementary hysteresis loops and uncorrelated input is treated analytically in detail. It is shown that the appearance of long-time tails in the output correlations is a quite general feature of this model. The exponent ? of the algebraic decay t-? , which may take any positive value, is determined by the tails of the input and the Preisach density. We identify the system classes leading to identical algebraic tails. These results imply the occurrence of 1/f noise for a large class of hysteretic systems.

Radons, Günter

2008-06-01

52

Inverted hysteresis loops: Experimental artifacts arising from inappropriate or asymmetric sample positioning and the misinterpretation of experimental data  

NASA Astrophysics Data System (ADS)

Inverted hysteresis loops (IHL) of negative net area have been measured for some films using vibrating sample magnetometer (VSM), SQUID magnetometer or magneto-optic Kerr effect magnetometer. All of the IHL were observed in the field direction along the hard axis. An IHL violates the thermo-mechanical second law. This work points out that an IHL arises when |M|?|M| (Mx and Mz: the parallel and normal to the field direction components of magnetization vector) if the sample is set at certain inappropriate positions in VSM and SQUID magnetometer experiments, and the sense voltage is solely attributed to Mx while it also relates to Mz.

Jin Hanmin; Dongsheng, Sun; Cunxu, Gao; Kim, Hyojin

2007-01-01

53

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

54

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

55

Hysteresis loops and compensation behavior of cylindrical transverse spin-1 Ising nanowire with the crystal field within effective-field theory based on a probability distribution technique  

NASA Astrophysics Data System (ADS)

We investigate the effect of a transverse field on a cylindrical core/shell spin-1 Ising nanowire, within the effective-field theory based on a probability distribution technique, in order to clarify how the relevant thermodynamic quantities such a magnetizations, hysteresis loops, compensation behaviors, are influenced by a transverse field. From these studies, following interesting phenomena are found. (i) Beside a singly hysteresis loop, double, triple or even quadruple hysteresis loops occurs in the system. (ii) The P and N types of compensation behavior are obtained in addition to the Q-, R- and S-types. We also compare our results with some experimental and theoretical results and find in a qualitatively good agreement.

Kocakaplan, Yusuf; Kantar, Ersin; Keskin, Mustafa

2013-10-01

56

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

57

Influence of a transverse static magnetic field on the magnetic hyperthermia properties and high-frequency hysteresis loops of ferromagnetic FeCo nanoparticles  

NASA Astrophysics Data System (ADS)

The influence of a transverse static magnetic field on the magnetic hyperthermia properties is studied on a system of large-losses ferromagnetic FeCo nanoparticles. The simultaneous measurement of the high-frequency hysteresis loops and of the temperature rise provides an interesting insight into the losses and heating mechanisms. A static magnetic field of only 40 mT is enough to cancel the heating properties of the nanoparticles, a result reproduced using numerical simulations of hysteresis loops. These results cast doubt on the possibility to perform someday magnetic hyperthermia inside a magnetic resonance imaging setup.

Mehdaoui, B.; Carrey, J.; Stadler, M.; Cornejo, A.; Nayral, C.; Delpech, F.; Chaudret, B.; Respaud, M.

2012-01-01

58

Double hysteresis loop induced by defect dipoles in ferroelectric Pb(Zr0.8Ti0.2)O3 thin films  

Microsoft Academic Search

Pb(Zr0.8Ti0.2)O3 (PZT80\\/20) thin films were deposited on the Pt(111)\\/Ti\\/SiO2\\/Si(100) substrates by RF magnetron sputtering. Mainly perovskite crystalline phase with highly (202)-preferred orientation, determined by x-ray diffraction, was formed in the lead zirconate titanate (PZT)(80\\/20) thin films. Polarization measurements of the unannealed and aged films showed a clear double hysteresis loop. However, the double hysteresis loop phenomenon was greatly suppressed in

Yunti Pu; Jiliang Zhu; Xiaohong Zhu; Yuansheng Luo; Mingsong Wang; Xuhai Li; Jing Liu; Jianguo Zhu; Dingquan Xiao

2011-01-01

59

Double hysteresis loop induced by defect dipoles in ferroelectric Pb(Zr{sub 0.8}Ti{sub 0.2})O thin films  

Microsoft Academic Search

Pb(Zr{sub 0.8}Ti{sub 0.2})O (PZT80\\/20) thin films were deposited on the Pt(111)\\/Ti\\/SiO\\/Si(100) substrates by RF magnetron sputtering. Mainly perovskite crystalline phase with highly (202)-preferred orientation, determined by x-ray diffraction, was formed in the lead zirconate titanate (PZT)(80\\/20) thin films. Polarization measurements of the unannealed and aged films showed a clear double hysteresis loop. However, the double hysteresis loop phenomenon was greatly

Pu Yunti; Zhu Jiliang; Zhu Xiaohong; Luo Yuansheng; Wang Mingsong; Li Xuhai; Liu Jing; Zhu Jianguo; Xiao Dingquan

2011-01-01

60

Evolution of Recrystallization by Changes in Magnetic Hysteresis Loop in a Non-Oriented Electric Steel Cold Rolled  

NASA Astrophysics Data System (ADS)

Non-oriented steels, with low carbon, are widely used in the fabrication of electrical motor nucleus. The performance of these motors is affected by the level of recrystallization. These steels can come from the steel plant in two different conditions: totally processed or semi-processed. The semi-processed steels have a partially deformed structure and are submitted to the final annealing process after reaching the end shape. An adequate annealing heat treatment is important to get an appropriate magnetic property. In the present study, samples of an electric steel, with the composition (0.05 wt% C, 1.28wt% Si, 0.29wt% Mn), cold rolled 50% in thickness, were withdrawn during the industrial heat treatment at temperatures of 575, 580, 600, 620 and 730 °C with the objective of evaluating the evolution of recrystalization with temperature. Magnetic properties were measured at room temperature in a vibrating sample magnetometer. Although the changes in magnetic hysteresis loop with temperature are difficult to observe, they have been identified by using pattern classification techniques, such as principal-component analysis and Karhunen-Loève expansion. These tools have been applied to vectors which are built from each hysteresis loop, properly renormalized, whose components correspond to amplitude of the loop at given equally spaced values of the renormalized field. The samples have been classified in four sets, namely, set A corresponding to temperatures 575/580, set B corresponding to temperatures 600/620, set C corresponding to the samples without annealing heat treatment, and set D corresponding to recrystallized samples. The results for the classification of the different microstructures have been obtained by using both techniques, and in particular a 100% success rate has been reached by using Karhunen-Loève expansion.

da Silva, F. E.; Freitas, F. N. C.; Abreu, H. F. G.; Gonçalves, L. L.; Moura, E. P.; Silva, M. R.

2011-06-01

61

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

62

Double hysteresis loop induced by defect dipoles in ferroelectric Pb(Zr0.8Ti0.2)O3 thin films  

NASA Astrophysics Data System (ADS)

Pb(Zr0.8Ti0.2)O3 (PZT80/20) thin films were deposited on the Pt(111)/Ti/SiO2/Si(100) substrates by RF magnetron sputtering. Mainly perovskite crystalline phase with highly (202)-preferred orientation, determined by x-ray diffraction, was formed in the lead zirconate titanate (PZT)(80/20) thin films. Polarization measurements of the unannealed and aged films showed a clear double hysteresis loop. However, the double hysteresis loop phenomenon was greatly suppressed in the PZT thin films annealed under pure oxygen, and thus they exhibited larger remnant polarization (Pr = 6.3 ?C/cm2). The related mechanism for the appearance of constricted and double hysteresis loops was investigated to be associated with the realignment and disassociation of defect dipoles via oxygen octahedral rotations or oxygen vacancy diffusion. The butterfly-shaped C-V characteristic curve with a valley gave further evidence for double hysteresis loop characteristic in the unannealed and aged PZT thin films.

Pu, Yunti; Zhu, Jiliang; Zhu, Xiaohong; Luo, Yuansheng; Wang, Mingsong; Li, Xuhai; Liu, Jing; Zhu, Jianguo; Xiao, Dingquan

2011-02-01

63

Double hysteresis loop induced by defect dipoles in ferroelectric Pb(Zr{sub 0.8}Ti{sub 0.2})O{sub 3} thin films  

SciTech Connect

Pb(Zr{sub 0.8}Ti{sub 0.2})O{sub 3} (PZT80/20) thin films were deposited on the Pt(111)/Ti/SiO{sub 2}/Si(100) substrates by RF magnetron sputtering. Mainly perovskite crystalline phase with highly (202)-preferred orientation, determined by x-ray diffraction, was formed in the lead zirconate titanate (PZT)(80/20) thin films. Polarization measurements of the unannealed and aged films showed a clear double hysteresis loop. However, the double hysteresis loop phenomenon was greatly suppressed in the PZT thin films annealed under pure oxygen, and thus they exhibited larger remnant polarization (P{sub r} = 6.3 {mu}C/cm{sup 2}). The related mechanism for the appearance of constricted and double hysteresis loops was investigated to be associated with the realignment and disassociation of defect dipoles via oxygen octahedral rotations or oxygen vacancy diffusion. The butterfly-shaped C-V characteristic curve with a valley gave further evidence for double hysteresis loop characteristic in the unannealed and aged PZT thin films.

Pu Yunti; Zhu Jiliang; Zhu Xiaohong; Luo Yuansheng; Wang Mingsong; Li Xuhai; Liu Jing; Zhu Jianguo; Xiao Dingquan [Department of Materials Science, Sichuan University, Chengdu 610064 (China)

2011-02-15

64

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

SciTech Connect

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

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

2012-03-01

65

Magnetic hysteresis loop technique as a tool for the evaluation of ? phase embrittlement in Fe–Cr alloys  

NASA Astrophysics Data System (ADS)

Fe-48 wt% Cr alloy was isothermally aged at 700 °C up to 250 h for the formation and growth of ? phase. Micro Vicker's hardness and magnetic hysteresis loop (MHL) measurements were carried out at various lengths of time by interrupting the test to observe the change in mechanical and magnetic properties respectively. A small volume fraction of ? phase did not produce any change in the hardness whereas a drastic decrease in remanence was found for its demagnetizing effect. The existence of ? phase was confirmed by transmission electron microscopy. The maximum induction of the alloy decreased with thermal ageing as the volume of ferrites decreased for the formation of non-magnetic ? phase. The volume fraction of ? phase was estimated from the maximum induction. The results showed that MHL technique can even detect 1% of ? phase in the alloy considering remanence as a measuring parameter. Hence MHL would be a powerful non-destructive evaluation technique for the evaluation of ? phase embrittlement in Fe–Cr alloys.

Mohapatra, J. N.; Kamada, Y.; Murakami, T.; Echigoya, J.; Kikuchi, H.; Kobayashi, S.

2013-02-01

66

Revealing the origin of the vertical hysteresis loop shifts in an exchange biased Co/YMnO3 bilayer.  

PubMed

We have investigated exchange bias effects in bilayers composed of the antiferromagnetic o-YMnO(3) and ferromagnetic Co thin film by means of SQUID magnetometry, magnetoresistance, anisotropic magnetoresistance and the planar Hall effect. The magnetization and magneto-transport properties show pronounced asymmetries in the field and magnetization axes of the field hysteresis loops. Both exchange bias parameters, the exchange bias field H(E)(T) as well as the magnetization shift M(E)(T), vanish around the Néel temperature T(N) =/~ 45 K. We show that the magnetization shift M(E)(T) is also measured by a shift in the anisotropic magnetoresistance and planar Hall resistance having a similar temperature dependence as the one obtained from magnetization measurements. Because the o-YMnO(3) film is highly insulating, our results demonstrate that the M(E)(T) shift originates at the interface within the ferromagnetic Co layer. To show that the main results obtained are general and not because of some special characteristics of the o-YMO(3) layer, similar measurements were done in Co/CoO micro-wires. The transport and magnetization characterization of the micro-wires supports the main conclusion that these effects are related to the response of the ferromagnetic Co layer at the interface. PMID:22907198

Barzola-Quiquia, J; Lessig, A; Ballestar, A; Zandalazini, C; Bridoux, G; Bern, F; Esquinazi, P

2012-08-21

67

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

Microsoft Academic Search

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

R. Ludwig; P. Bretchko; S. Makarov

2002-01-01

68

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

SciTech Connect

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

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

2000-11-01

69

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

70

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

71

Origin of anomalous hysteresis loops induced by femtosecond laser pulses in GdFeCo amorphous films  

Microsoft Academic Search

A controllable pump-pulse-number magneto-optical Kerr technique combined with an initializing field scanning approach is developed to eliminate and identify memory and accumulation effects, respectively, from external field history and multiple pulse excitations. A series of anomalous loops of GdFeCo films are measured for different amount of pump pulses using this technique, revealing that serious memory and accumulation effects exist in

Chudong Xu; Zhifeng Chen; Daxin Chen; Shiming Zhou; Tianshu Lai

2010-01-01

72

Constricted double loop hysteresis and exchange bias attributed to the surface anisotropy in nanocrystalline La1/3Sr2/3Fe1-xCrxO3  

NASA Astrophysics Data System (ADS)

We investigate magnetic properties of nanocrystalline ferrites with composition La1/3Sr2/3Fe1-xCrxO3 (LSFCO) for x=0, 0.02, 0.04 and 0.06. Thermal variation of zero field cooled magnetization displays a weak signature close to the charge (TCO) as well as antiferromagnetic ordering for x=0, 0.02 and 0.04. In addition, another disordered glassy magnetic transition (Tg) is noticed for all the compositions. Tg is predominantly observed, although signature of charge ordering almost disappears for x=0.06. Interestingly, a constricted double loop type magnetic hysteresis loop is observed for x=0.02. This structure in the hysteresis loop disappears with further increase in Cr substitution. A systematic shift in the magnetic hysteresis loop is observed for all the compositions, while samples are cooled in a static magnetic field, which is the manifestation of exchange bias (EB) effect. The EB field (HE) and magnetization (ME) decrease remarkably due to minor Cr substitution at x=0.02 and then it reveals a sluggish increase with increasing x. For x=0.04 the EB effect emerges below ˜TCO, increases sluggishly with lowering of temperature and below ˜Tg, it increases rapidly. The cooling field dependence exhibits significant increase of HE and ME for x=0.04, which is associated with the considerable increase of coercivity. Possible origin of EB correlated with the magnetic phase coexistence has been argued for nanocrystalline LSFCO.

Sabyasachi, Sk.; Patra, M.; Majumdar, S.; Giri, S.

2013-10-01

73

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

74

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

75

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

76

[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

77

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

78

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

79

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

80

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

81

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

82

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

83

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

84

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

85

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

86

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

87

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

88

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.

89

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

90

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

91

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

92

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

93

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

94

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

95

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

96

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

97

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

98

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

99

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

100

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

101

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

102

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

103

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

104

Effect of tensile and compressive stress on dynamic loop shapes and power losses of Fe-Si electrical steels  

NASA Astrophysics Data System (ADS)

Magnetic energy losses and hysteresis loops have been determined in Fe-Si non-oriented laminations as a function of the applied compressive and tensile stress, made to range between -50 and +50 MPa. The loss separation analysis has been carried out in association with hysteresis loop calculation by means of the Dynamic Preisach Model. The strong modifications to the hysteresis loop and area introduced in a specific way by compressive stresses can be correctly accounted for by modelling.

Lobue, M.; Basso, V.; Fiorillo, F.; Bertotti, G.

1999-05-01

105

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

106

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

107

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

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

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

120

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

121

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

122

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

123

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

124

Loop Representations  

Microsoft Academic Search

The loop representation plays an important role in canonical quantum gravity because loop variables allow a natural treatment of the constraints. In these lectures we give an elementary introduction to (i) the relevant history of loops in knot theory and gauge theory, (ii) the loop representation of Maxwell theory, and (iii) the loop representation of canonical quantum gravity.

Bernd Brugmann

125

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

126

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

127

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

128

Simulation of butterfly loops in ferroelectric materials  

Microsoft Academic Search

Ferroelectric materials exhibit complex behaviour upon electric and mechanical loading. Their change of polarization and length is accompanied by hysteresis. The so-called butterfly loop characterizing the strain due to an applied electric field is striking. As these materials are used in technical applications as sensors, actuators, and non-volatile memory units, the ability to simulate these hysteretic phenomena is important. Here,

H. Sahota

2004-01-01

129

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

130

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

131

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

132

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

133

Bistability threshold inside hysteresis loop of nonlinear fiber Bragg gratings  

Microsoft Academic Search

We show the Cross Phase Modulation (XPM) effect between CW probe that operates in bistability region and strong Gaussian pump in a Fiber Bragg Grating (FBG) by Implicit 4th Order Runge-Kutta Method. The XPM effect results in three unique nonlinear switching behaviors of the probe transmission depending on the pump peak intensity and its Full Width Half Maximum (FWHM) value.

Yosia Yosia; Shum Ping; Lu Chao

2005-01-01

134

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

135

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

136

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

137

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

138

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

139

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

140

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

141

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

142

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

143

Loop Representations  

Microsoft Academic Search

The loop representation plays an important role in canonical quantum gravity\\u000abecause loop variables allow a natural treatment of the constraints. In these\\u000alectures we give an elementary introduction to (i) the relevant history of\\u000aloops in knot theory and gauge theory, (ii) the loop representation of Maxwell\\u000atheory, and (iii) the loop representation of canonical quantum gravity. (Based\\u000aon

B. Bruegmann

1993-01-01

144

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

145

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

146

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

147

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

148

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

149

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

150

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

151

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

152

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

153

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

154

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-based pH-ISFET devices have been measured using a constant current constant voltage (CCCV) readout circuit. The drift rates were obtained by long-time monitoring for 12 h in pH = 1, 3, 5, 7, 9, and 11 buffer solutions, which indicated that the drift rate increased with the pH value. The hysteresis effect was investigated by exposing the AlN gate ISFET in pH = 7-3-7-11-7 loop cycles with loop times of 960 s, 1920 s and 3840 s, and the magnitudes of hysteresis of 1.0, 1.5 and 4.5 mV were obtained, respectively. The temperature coefficient of hysteresis was found to be approximately 0.234 mV/°C. In addition, it was also found that the hysteresis width with pH started from acid side is smaller than that started from basic side, which results in an asymmetric hysteresis effect.

Chiang, Jung-Lung; Chou, Jung-Chuan; Chen, Ying-Chung; Liau, Guo Shiang; Cheng, Chien-Chuan

2003-08-01

155

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

156

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

157

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

158

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

159

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

160

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

161

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

162

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

163

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

164

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

165

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

166

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

167

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

168

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

169

Life, Liberty, and the Pursuit of P. E  

Microsoft Academic Search

Life, Liberty, and the Pursuit of P.E. has been in the works for so long that I honestly can't remember where the original idea came from. I started writing it during the summer after my freshman year; I can picture myself sitting on the couch at my parents' house, typing on my laptop at 2 am (because I do my

Rachel Mills

2011-01-01

170

QED radiative corrections to the process e-p --> ?e-p  

NASA Astrophysics Data System (ADS)

The process e-p --> ?e-p will be used as a fast luminosity monitor for HERA. In this article we consider the QED radiative corrections to this process. This includes the computation of the soft and hard bremsstrahlung processes which are computed without any approximation. In order to avoid numerical instabilities due to gauge cancellations, which can become unacceptably large, we use a special technique to rewrite the matrix element. In addition, special attention is paid to perform the phase space integration and to evaluate the scalar loop integrals in a numerically stable manner. We find that the radiative corrections (including hard bremsstrahlung) are smaller than 1% of the cross section at tree level.

van der Horst, M.

1990-12-01

171

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

172

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

173

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

174

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

175

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

176

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

177

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

178

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

179

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.

180

[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

181

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

182

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

183

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

184

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

185

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

186

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

187

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

188

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

189

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

190

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

191

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

192

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

193

A dual-phase homogenization theory for the hysteresis and butterfly-shaped behavior of ferroelectric single crystals  

Microsoft Academic Search

Based on the mechanism of domain switch and a micromechanics-based thermodynamic approach, a dual-phase homogenization theory is developed to calculate the hysteresis loops of ferroelectric single crystals. Unlike the classical phenomenological theories, this dual-phase model is capable of delivering the evolution of new domain concentration, and it further indicates that the driving force for domain switch under a pure electric

N. Srivastava; G. J. Weng

2006-01-01

194

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

195

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

196

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

197

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

198

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

199

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

200

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

201

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

202

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

203

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

204

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

205

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

206

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

207

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

208

A mechanism of hysteresis in brightness-voltage characteristics of ZnS: Mn-based light-emitting MISIM structures  

Microsoft Academic Search

The hysteresis phenomenon in brightness-voltage characteristics of ZnS: Mn-based thin-film metal-insulator-semiconductor-insulator-metal\\u000a (MISIM) structures was investigated. The shape of the hysteresis loop depends on the frequency of an applied ac electric field.\\u000a The phenomenon is explained in terms of a suggested theoretical model that postulates the presence of weakly and strongly\\u000a localized charges in the semiconducting layer. Numerical model results are

Ya. I. Alivov; A. N. Gruzintsev

2000-01-01

209

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

210

Bilayer piezoelectric/electrostrictive (P/E) dome unimorph.  

PubMed

We present a new type of actuator named bilayer piezoelectric/electrostrictive dome unimorph (BIPEDU), fabricated by attaching a piezoelectric-electrostrictive monolithic bilayer composites (PE-MBLC) to a metal plate. Various ratios of piezoelectric/electrostrictive (P/E) volume percent were used to form PE-MBLC. It was found that d(33)(eff) and K(eff) in PE-MBLC follow the series 2-2 composite mixing rule. However, the measured results were slightly lower than those of the calculated values because of a large difference in dielectric displacement between piezoelectric and electrostrictive layers and because the electrostrictor acts as the resistor that impedes the domain switching in piezoelectric layer during poling. In addition, we have investigated the field-induced displacement in PE-MBLC and BIPEDU actuators. In comparison, the displacement of BIPEDU actuators was much higher than that of PE-MBLC actuators. This was attributed to the good quality of bonding between ceramic and metal, which contributed to the proper stress/force transfer, as well as the metal sheet, which acted as a flextentional structure for PE-MBLC to generate more axial displacement in BIPEDU actuators. The load dependence of displacement in BIPEDU was obtained. In addition, the BIPEDU showed high reliability during the displacement cyclic testing. PMID:20040411

Ngernchuklin, Piyalak; Safari, Ahmad

2009-12-01

211

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

212

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

213

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

214

Water Stream "Loop-the-Loop"  

ERIC Educational Resources Information Center

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

Jefimenko, Oleg

1974-01-01

215

Water Stream "Loop-the-Loop"  

ERIC Educational Resources Information Center

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

Jefimenko, Oleg

1974-01-01

216

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

217

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

218

Comparative analysis of closed-loop current control of grid connected converter with LCL filter  

Microsoft Academic Search

Voltage source inverters (VSIs) with output LCL filters are the key interfaces for today's distributed energy resource. There are mainly two groups of current control methods of a VSI: direct error tracking control with PWM, and closed-loop feedback control. Direct current error control, such as predictive control and hysteresis control, has some drawbacks like system parameter sensitivity, variable switching frequency,

Jinwei He; Yun Wei Li

2011-01-01

219

Origin of Constricted Magnetization Loops in Hard Rolled Nickel at Low Temperatures.  

National Technical Information Service (NTIS)

Constricted magnetization hysteresis loops were observed at 4.2 degrees K in tapes of spectroscopically pure Ni, which were prepared by cold-rolling with a reduction in thickness of 95% when the driving field was applied perpendicularly to the rolling pla...

A. A. Hirsch Z. Eliezer

1967-01-01

220

A phase-locked loop control system for a synchronous motor  

Microsoft Academic Search

The viewpoint that a hysteresis synchronous motor operates similar to a phase-locked loop of the type common in communications applications is discussed. This viewpoint leads to a simple electrical equivalent circuit model for the motor. The model adequately describes the motor's motion with respect to synchronism and, specifically, the well-known hunting characteristic phenomenon. The motor's hunting characteristic cannot be tolerated

G. Volpe

1970-01-01

221

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

222

Auto-loop improvement  

SciTech Connect

The Consolidated Edison Company of New York, Inc. (Con Edison) has developed a computer program that predicts the reliability of auto-loops and optimizes loop design. This paper describes the application of this program to auto-loops in an urban area, the calculation of loop-specific failure data using a Bayesian data update process and the development of strategies for enhancing loop reliability. Reliabilities predicted using loop-specific data are compared to those obtained using generic data. The paper also demonstrates two alternative means of enhancing auto-loop reliability: adding protective devices to a loop and realigning its main run.

Hong, L.; Yueh, W.H. (Consolidated Edison Co. of New York, Inc., New York, NY (United States)); Allen, D.J.

1994-04-01

223

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

224

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

225

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

226

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

227

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

228

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

229

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

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

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

NASA Astrophysics Data System (ADS)

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

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

2002-08-01

238

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

239

Fast flux locked loop  

DOEpatents

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

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

2002-09-10

240

Loop transfer matrix and loop quantum mechanics  

NASA Astrophysics Data System (ADS)

The gonihedric model of random surfaces on a 3d euclidean lattice has equivalent representation in terms of transfer matrix K(Qi,Qf) which describes the propagation of loops Q. We extend the previous construction of loop transfer matrix to the case of non-zero self-intersection coupling constant kappa. We introduce loop generalization of Fourier transformation which allows to diagonalize transfer matrices depending on symmetric difference of loops and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out analogy with quantum mechanics of point particles, to introduce conjugate momentum loop P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. Particularly the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops.

Savvidy, George K.

2000-09-01

241

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

242

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

243

VLF Loop Array Antenna.  

National Technical Information Service (NTIS)

The report describes a directional loop array antenna for very low frequency (VLF) reception. The array comprises four closely spaced loop antennas forming a unidirectional reception pattern with a main beam of less than 43 deg between half power points. ...

E. W. Seeley

1978-01-01

244

Phase-locked loops  

Microsoft Academic Search

An attempt to systematically outline the work done in the area of phase-locked loops which are now used in modern communication system design is presented. The analog phase-locked loops are well documented in several books but discrete, analog-digital, and digital. phase-locked loop work is scattered. Apart from discussing the various analysis, design, and application aspects of phase-locked loops, a number

S. C. Gupta

1975-01-01

245

On Open Loop and Closed Loop Nash Strategies.  

National Technical Information Service (NTIS)

For deterministic nonzero-sum differential games, every open loop Nash strategy set is a closed loop Nash strategy set. The converse, that the open loop strategy set generated by a closed loop Nash strategy set is Nash, is false.

N. R. Sandell

1973-01-01

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

Effects of Contact Angle Hysteresis on Ice Adhesion and Growth over Superhydrophobic Surfaces under Dynamic Flow Conditions  

SciTech Connect

In this paper, the iceophobic properties of superhydrophobic surfaces are investigated under dynamic flow conditions by using a closed loop low-temperature wind tunnel. Superhydrophobic surfaces were prepared by coating the substrates of aluminum and steel plates with nano-structured hydrophobic particles. The superhydrophobic plates along with uncoated control ones were exposed to an air flow of 12 m/s and 20 F accompanying micron-sized water droplets in the icing wind tunnel and the ice formation and accretion were probed by high-resolution CCD cameras. Results show that the superhydrophobic coatings significantly delay the ice formation and accretion even under the dynamic flow condition of the highly energetic impingement of accelerated super-cooled water droplets. It is found that there is a time scale for this phenomenon (delay of the ice formation) which has a clear correlation with the contact angle hysteresis and the length scale of surface roughness of the superhydrophobic surface samples, being the highest for the plate with the lowest contact angle hysteresis and finer surface roughness. The results suggest that the key parameter for designing iceophobic surfaces is to retain a low contact angle hysteresis (dynamic property) and the non-wetting superhydrophobic state under the hydrodynamic pressure of impinging droplets, rather than to only have a high contact angle (static property), in order to result in efficient anti-icing properties under dynamic conditions such as forced flows.

Sarshar, Mohammad Amin [Stevens Institute of Technology, Hoboken, New Jersey; Swarctz, Christopher [Stevens Institute of Technology, Hoboken, New Jersey; Hunter, Scott Robert [ORNL; Simpson, John T [ORNL; Choi, Chang-Hwan [Stevens Institute of Technology, Hoboken, New Jersey

2012-01-01

254

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

255

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

256

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

257

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

258

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

259

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

260

Work distribution functions for hysteresis loops in a single-spin system  

Microsoft Academic Search

We compute the distribution of the work done in driving a single Ising spin with a time-dependent magnetic field. Using Glauber dynamics we perform Monte Carlo simulations to find the work distributions at different driving rates. We find that in general the work distributions are broad with a significant probability for processes with negative dissipated work. The special cases of

Rahul Marathe; Abhishek Dhar

2005-01-01

261

Hysteresis loops of individual Co nanostripes measured by magnetic force microscopy  

PubMed Central

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

2011-01-01

262

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

PubMed

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

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

2012-11-29

263

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

National Technical Information Service (NTIS)

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

D. C. Jiles

1992-01-01

264

Butterfly Hysteresis Loop at Nonzero Bias Field in Antiferromagnetic Molecular Rings: Cooling by Adiabatic Magnetization  

Microsoft Academic Search

At low temperatures, the magnetization of the molecular ferric wheel NaFe6 exhibits a step at a critical field Bc due to a field-induced level crossing. By means of high-field torque magnetometry we observed a hysteretic behavior at the level crossing with a characteristic butterfly shape which is analyzed in terms of a dissipative two-level model. Several unusual features were found.

O. Waldmann; R. Koch; S. Schromm; P. Müller; I. Bernt; R. W. Saalfrank

2002-01-01

265

Relaxation of hysteresis loop in a single crystal of YBa2Cu4O8  

NASA Astrophysics Data System (ADS)

Magnetic relaxation has been studied for Y1Ba2Cu4O8 in order to look for changes in the relaxation rates that arise because different pinning mechanisms dominate in different magnetic field regimes. In the low field regime where the Bean-Livingston surface barrier dominates, the vortices exit on a field decreasing branch with a relaxation rate about ten times faster than they enter on a corresponding field increasing branch. In high magnetic fields where bulk pinning dominates, the relaxation rates for field increasing and field decreasing are essentially the same.

Xu, Ming; Finnemore, D. K.; Crabtree, G. W.; Vinokur, V. M.; Zhang, K.; Dabrowski, B.; Hinks, D. G.

1994-02-01

266

Relaxation of hysteresis loop in a single crystal of YBa2Cu4O8  

NASA Astrophysics Data System (ADS)

Magnetic relaxation has been studied for YBa2Cu4O8 in order to look for changes in the relaxation rates that arise because different pinning mechanisms dominate in different magnetic field regimes. In the low field regime where the Bean-Livingston surface barrier dominates, the vortices exit on a field decreasing branch with a relaxation rate about ten times faster than they enter on a corresponding field increasing branch. In high magnetic fields where bulk pinning dominates, the relaxation rates for field increasing and field decreasing are essentially the same.

Xu, Ming; Finnemore, D. K.; Crabtree, G. W.; Vinokur, V. M.; Hinks, D. G.; Zhang, K.; Dabrowski, B.

1993-04-01

267

Interactions of Cations with RNA Loop-Loop Complexes  

PubMed Central

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

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

2011-01-01

268

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

269

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

270

Laminated BEAM loops  

NASA Astrophysics Data System (ADS)

BEAM sensors include treated loops of optical fiber that modulate optical throughput with great sensitivity and linearity, in response to curvature of the loop out of its plane. This paper describes BEAM sensors that have two loops treated in opposed fashion, hermetically sealed in flexible laminations. The sensors include an integrated optoelectronics package that extracts curvature information from the treated portion of the loops while rejecting common mode errors. The laminated structure is used to sense various parameters including displacement, force, pressure, flow, and acceleration.

Danisch, Lee A.

1996-10-01

271

Phase diagram based description of the hysteresis behavior of shape memory alloys  

SciTech Connect

In this paper, the authors develop a consistent mathematical description of martensite fraction evolution during athermal thermoelastic phase transformation in a shape memory alloy (SMA) induced by a general thermomechanical loading. The global kinetic law is based on an experimentally defined stress-temperature phase diagram, transformation functions for a one-dimensional SMA body and a novel vector hysteresis model. The global kinetic law provides the phase fraction history given a loading path on the stress-temperature phase diagram and an initial value of martensite fraction. The phase transformation is considered to occur only within transformation strips on the phase diagram and only on loading path segments oriented in the transformation direction. The developed procedure can be used to model a range of different SMA transformation behaviors depending on the choice of transformation functions and local kinetic law algorithms. The phase fraction evolution is examined for a number of characteristic examples, including cyclic loading resulting in oscillatory transformation paths, and internal loops of partial transformation with associated attractor loops. Differences between the various local kinetic law algorithms used in the overall framework are highlighted. The simulation results using a cosine transformation function are found to be in excellent agreement with experimental data.

Bekker, A.; Brinson, L.C. [Northwestern Univ., Evanston, IL (United States)

1998-06-12

272

Separation of the Longitudinal and Transverse Cross Sections in the p(e,eâ²K{sup +})Î and p(e,eâ²K{sup +})Σ° Reactions  

Microsoft Academic Search

We report measurements of cross sections for the reaction p(e,eâ²K{sup +})Y, for both the Lambda and Sigmaâ hyperon states, at an invariant mass of W = 1.84 GeV and four-momentum transfers 0.5 < Q² < 2 (GeV\\/c)². Data were taken for three values of virtual photon polarization, allowing the decomposition of the cross sections into longitudinal and transverse components. The

R. M. Mohring; David Abbott; Abdellah Ahmidouch; T. A. Amatuni; Pawel Ambrozewicz; Tatiana Angelescu; Christopher Armstrong; John Arrington; Ketevi Assamagan; Steven Avery; Kevin Bailey; Kevin Beard; S. Beedoe; Elizabeth Beise; Herbert Breuer; Roger Carlini; Jinseok Cha; C. Chang; Nicholas Chant; Evaristo Cisbani; Glenn Collins; William Cummings; Samuel Danagoulian; Raffaele De Leo; Fraser Duncan; James Dunne; Dipangkar Dutta; T. Eden; Rolf Ent; Laurent Eyraud; Lars Ewell; John Finn; H. Terry Fortune; Valera Frolov; Salvatore Frullani; Christophe Furget; Franco Garibaldi; David Gaskell; Don Geesaman; Paul Gueye; Kenneth Gustafsson; Jens-ole Hansen; Mark Harvey; Wendy Hinton; Ed Hungerford; Mauro Iodice; C. Jackson; Cynthia Keppel; Wooyoung Kim; Kouichi Kino; Douglas Koltenuk; Serge Kox; Laird Kramer; Antonio Leone; Allison Lung; David Mack; Richard Madey; M. Maeda; Stanislaw Majewski; Pete Markowitz; T. MART; C. J. Martoff; David Meekins; A. Mihul; Joseph Mitchell; Hamlet Mkrtchyan; Sekazi Mtingwa; Maria-Ioana Niculescu; R. Perrino; David Potterveld; John Price; Brian Raue; Jean-Sebastien Real; Joerg Reinhold; Philip Roos; Teijiro Saito; Geoff Savage; Reyad Sawafta; Ralph Segel; Samuel Stepanyan; Paul Stoler; Vardan Tadevosyan; Liguang Tang; Liliana Teodorescu; Tatsuo Terasawa; Hiroaki Tsubota; Guido Urciuoli; Jochen Volmer; William Vulcan; T. Welch; Robert Williams; Stephen Wood; Chen Yan; Benjamin Zeidman

2003-01-01

273

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

274

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

275

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

276

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

277

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

278

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

279

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

SciTech Connect

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

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

2008-05-05

280

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

281

Molten salt test loop  

Microsoft Academic Search

The objective of the Molten Salt Test Loop Project was to design, construct, and demonstrate operation of an outdoor high temperature molten salt test facility. This facility is operational, and can now be used to evaluate materials and components, and the design features and operating procedures required for molten salt heat transport systems. The initial application of the loop was

J. R. Schuster; G. H. Eggers

1980-01-01

282

Fiber loop optical buffer  

Microsoft Academic Search

Fiber loop optical buffers enable data storage for discrete time intervals and therefore appear suitable for applications in optical asynchronous transfer mode (OATM)-based networks where data are transmitted in cells of fixed length. In this paper, the feasibility and the limitations of optical data storage in a fiber loop optical buffer are studied theoretically and experimentally, A model of a

R. Langenhorst; M. Eiselt; W. Pieper; G. Grosskopf; R. Ludwig; L. Kuller; E. Dietrich; H. G. Weber

1996-01-01

283

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

284

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

285

Enhanced hysteresis in the semiconductor-to-metal phase transition of VO2 precipitates formed in SiO2 by ion implantation  

NASA Astrophysics Data System (ADS)

A strongly enhanced hysteresis with a width of >34 °C has been observed in the semiconductor-to-metal phase transition of submicron-scale VO2 precipitates formed in the near-surface region of amorphous SiO2 by the stoichiometric coimplantation of vanadium and oxygen and subsequent thermal processing. This width is approximately an order of magnitude larger than that reported previously for the phase transition of VO2 particles formed in Al2O3 by a similar technique. The phase transition is accompanied by a significant change in infrared transmission. The anomalously wide hysteresis loop observed here for the VO2/SiO2 system can be exploited in optical data storage and switching applications in the infrared region.

Lopez, R.; Boatner, L. A.; Haynes, T. E.; Haglund, R. F.; Feldman, L. C.

2001-11-01

286

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

287

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

288

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

289

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

290

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

291

Analysis of closed loop control and sensor for a reactive sputtering drum coater  

NASA Astrophysics Data System (ADS)

The reactive sputtering process is characterized by a hysteresis of reactive gas concentration and reactive gas flow [Schiller, Thin Solid Films 118, 255 (1984); Affinito and Parsons, J. Vac. Sci. Technol A. 2, 1275 (1984)]. The precise control of the reactive sputtering process requires maintaining operation at points on the hysteresis that ensures the desired high sputter flux and deposited thin film stoichiometry. The hysteresis is highly nonlinear in these preferred operating regimes. The practical challenge of meeting this in a reactive sputtering batch coating system requires a control system that can compensate for changes in reaction rate for various sputtered metals, reactive gas sticking coefficients, and system pumping speed. Closed loop control algorithms that rapidly bring the reactive sputtering system to the desired hysteresis steady state operating point are desired for multilayer applications such as thin film interference filters that require many target starts (and stops). Conventional methods of starting the reactive sputtering process such as temporally ramping target power, voltage or current and target shutters are undesirable for precision thin film interference filters. We present a reactive gas sensor and analysis of the proportional-integral-derivative closed loop control algorithm for an industrial reactive sputtering batch drum coater. The key enabler of the control algorithms is a reactive gas sensor employed on these drum coaters that exhibits a temporal response of several hundred milliseconds. We discuss how elements from control theory applied to the reactive sputtering process can determine what points on the hysteresis will be the most difficult to control and the limits to implementation for an industrial system. .

George, M. A.; Craves, E. A.; Shehab, R.; Knox, K.

2004-07-01

292

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

293

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

294

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

295

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

296

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

297

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

298

Dehumidification -- Closed loop systems  

SciTech Connect

Dehumidification is the removal of water from the air. Dehumidification equipment treats the ambient air before it is introduced to the enclosure. A closed loop system is one that theoretically routes all the air exiting an enclosure through the appropriate filter media and treatment equipment and then returns it to the enclosure. By establishing a closed loop system, the ``treated`` air is continuously processed, which improves the efficiency of this operation. The generic types of dehumidification equipment and their application in a closed loop system will be presented. This article will deal solely with the use of dehumidification and other related equipment used to control the environment within the work enclosure.

Wyatt, C.H. [Enviro-Air Control Corp., Houston, TX (United States); Crowe, A.R. [C.H. Heist Ltd., Oakville, Ontario (Canada)

1996-05-01

299

Multiprotein DNA looping.  

PubMed

DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switchlike transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance. PMID:16803410

Vilar, Jose M G; Saiz, Leonor

2006-06-15

300

Large lithium loop experience  

SciTech Connect

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

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

1981-10-01

301

Natively Unstructured Loops Differ from Other Loops  

PubMed Central

Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions) differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%–70% of all worm proteins observed to have more than seven protein–protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested that long unstructured loops are a major part of unstructured regions in molecular networks.

Schlessinger, Avner; Liu, Jinfeng; Rost, Burkhard

2007-01-01

302

Dissociated Prismatic Dislocation Loops.  

National Technical Information Service (NTIS)

Transmission electron microscopy observations on heterogeneous precipitation in dilute aluminum-base silver alloys tend to support a previously proposed model for dissociated prismatic dislocation loops. During the initial stage of precipitation, the perf...

A. K. Eikum

1968-01-01

303

Heating of postflare loops  

SciTech Connect

The heating of postflare loops by slow MHD shocks is considered. Although such loops were once thought to represent the dying remnant of a two-ribbon flare, it is now realized that they are the main part of such an event and begin very early on. It is shown that, if the local temperature of a loop, its local angle of inclination to the vertical, and ambient coronal conditions are known from observations, then simple analytical formulae give the rise speed of the shocks and the magnitude of the evaporative flow incident upon them. The formulae are applied as an example to the 1973 July 29 and 1980 May 21 two-ribbon flares, and reasonable agreement with rise-speed observations is found. It is therefore claimed that shock heating is a viable method for heating postflare loops for the long times observed.

Cargill, P.J.; Priest, E.R.

1983-03-01

304

Hot giant loop holography  

SciTech Connect

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

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

2010-07-15

305

Thrown for a Loop  

NSDL National Science Digital Library

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

VU Bioengineering RET Program, School of Engineering,

306

Closed-Loop Systems  

NSDL National Science Digital Library

Teachers' Domain presents this interactive lesson on closed-loop systems, which includes an animation that describes the typical components of a closed-loop system (error detector, controller, actuator, and measurement device), and describes the input and output signals for each component. The interactive lesson includes three sections: introduction, system overview, and adjustment scenarios. The activity includes 18 screens with reading materials as well as a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

2010-10-11

307

Pseudoresonance Argand loops  

Microsoft Academic Search

The root and logarithmic singularities of the partial amplitude corresponding to a box diagram with a resonance and a particle in the intermediate state lead to resonance-like loops (pseudoresonances) on the Argand diagram in the case of hadronic masses and widths. Examples of pseudoresonance loops are given for the reactions ..pi..d (..delta..N) ..pi..d, NN (..delta..N) ..pi..d, ..pi..N (rhoN) ..pi..N, KN

I. M. Narodetskii; Y. A. Simonov

1978-01-01

308

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

NSDL National Science Digital Library

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

Sullivan, Megan

2005-07-01

309

Understanding Warm Coronal Loops  

NASA Astrophysics Data System (ADS)

One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warm (~ 1 MK) coronal loops are much denser than expected for quasi-static equilibrium. It has been shown that the excess density can be explained if loops are bundles of unresolved strands that are heated impulsively and quasi-randomly to very high temperatures. This picture of nanoflare heating predicts that neighboring strands of different temperature should coexist and therefore that loops should have multi-thermal cross sections. In particular, emission should be produced at temperatures hotter than 2 MK. Such emission is sometimes but not always seen, however. We offer two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We verify these possibilities with numerical hydro simulations. Time permitting, we will show FeXVII line profile observations from EIS/Hinode that support the existence of nanoflare heating. Work supported by NASA and ONR.

Klimchuk, J. A.; Karpen, J. T.; Patsourakos, S.

2007-12-01

310

Magnetic Hysteresis Parameters and Day-Plot Analysis to Delineate Diagenetic Alteration in Gas Hydrate-Bearing Sediments  

NASA Astrophysics Data System (ADS)

Gas hydrates are naturally occurring cage structures of ice found in continental slope and permafrost sediments. They contain vast quantities of methane which is important both as a climate driver and an energy resource. Hydrate formation alters the redox potential of interstitial fluids which can in turn alter magnetic minerals. Thus magnetic methods can help delineate diagenetic pathways, provide a proxy method to map out past hydrate occurrences, and eventually lead to new remote sensing methods in prospecting for gas hydrates. We present data acquired using a J-Meter Coercivity Spectrometer. Induced and remanent magnetism are simultaneously measured on 1.5 cc samples as they spin on a 50 cm diameter disk, 20 times per second. The applied field ramps between ± 500 mT to produce a hysteresis loop in 7 minutes. Sub-second viscous decay is measured to provide a proxy for the amount of superparamagnetism present. The rapid and simple measurements made possible by this robust machine are ideal for core logging. Measurements made on frozen core from the Mallik permafrost gas hydrate field in Canada's Northwest Territories demonstrates that the magnetic properties are dependent on the concentration of gas hydrate present. Day-plots of magnetic hysteresis parameter ratios distinguish the magnetic carriers in gas hydrate rich sediments. The original magnetite is often reduced to sulphide when gas hydrate concentration exceeds 40%. In other high-concentration gas hydrate horizons, fine single-domain (SD) grains of magnetite apparently dissolve leaving nothing but large multi-domain (MD) magnetite grains. Independently measured superparamagnetism is shown to push hysteresis ratios off the hyperbola expected for SD-MD mixtures, as predicted by Dunlop [JGR, 10.10291/2001JB000486, 2002]. Magnetic study of host sediments in gas hydrate systems provides a powerful core-logging tool, offers a window into the processes of gas hydrate formation, and forms the basis for quantitative analysis of magnetic surveys over gas hydrate fields.

Enkin, R. J.; Baker, J.; Nourgaliev, D.; Iassonov, P.

2005-12-01

311

Frequency and Phase Lock Loop  

Microsoft Academic Search

A new electronic subsystem has been developed: The frequency and phase lock loop. It has an extended acquisition range compared to the standard phase lock loop. It will be advantageous to use this new loop in all applications where a simultaneous need for large acquisition range and a narrow tracking bandwidth can justify the added complexity of the new loop.

Richard Citta

1977-01-01

312

N Reactor secondary loop contamination  

Microsoft Academic Search

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

Stepnewski

1963-01-01

313

Initial observation of magnetization hysteresis and quantum tunneling in mixed manganese-lanthanide single-molecule magnets.  

PubMed

The preparation of a new family of mixed transition metal/lanthanide clusters is reported. The reaction of [Mn3O(O2CPh)6(py)2(H2O)] with Ln(NO3)3 (Ln = Nd, Gd, Dy, Ho, and Eu) in a 1:2 molar ratio in MeOH/MeCN (1:20 v/v) leads to dark crystals in 55-60% isolated yield of complexes all containing the [Mn11Ln4]45+ core. The Dy compound has been found to give out-of-phase AC susceptibility signals, suggesting it might be a single-molecule magnet (SMM). This was confirmed by the observation of magnetization hysteresis loops. An Arrhenius plot constructed from magnetization decay data gave a barrier to relaxation of 9.3 K and showed the temperature-independent relaxation at very low temperatures indicative of quantum tunneling of magnetization. This is the initial demonstration of hysteresis and quantum behavior in a mixed 3d/4f SMM. PMID:15571379

Mishra, Abhudaya; Wernsdorfer, Wolfgang; Abboud, Khalil A; Christou, George

2004-12-01

314

Magnetic hysteresis parameters for two Antarctic (Yamato-82050, Yamato-791717) and two African (Acfer-059, Acfer-202) carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

We have selected four carbonaceous chondrites of CO3 type for the study of meteoritic magnetism. We apply the approach regarding carbonaceous chondrites in terms of a magnetic binary system. This model explains meteoritic magnetism as the mixture of two magnetic components: a high coercivity magnetic mineral including SD particles and a low coercivity carrier including MD particles. The construction of the model is based on parameters of magnetic hysteresis loop. We have measured the average magnetic susceptibility per unit mass and made AF demagnetization of NRM (measured using the SQUID magnetometer) to determine the size of the medium destructive field. The thermal experiments to find the Curie unblocking temperatures of magnetic carriers has been also performed. Data indicate differentiations among studied chondrites of type CO3.

Krol, Elizabeth A.; Lang, Bruno

1997-03-01

315

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

316

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

317

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

318

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

319

Degradation and capacitance: voltage hysteresis in CdTe devices  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

320

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

321

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

322

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

323

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

324

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

325

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

Microsoft Academic Search

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

Imran A. Zualkernan; Dom Parser

2005-01-01

326

Hysteresis, avalanches, and disorder-induced critical scaling: A renormalization-group approach  

SciTech Connect

Hysteresis loops are often seen in experiments at first-order phase transformations, when the system goes out of equilibrium. They may have a macroscopic jump (roughly as in the supercooling of liquids) or they may be smoothly varying (as seen in most magnets). We have studied the nonequilibrium zero-temperature random-field Ising-model as a model for hysteretic behavior at first-order phase transformations. As disorder is added, one finds a transition where the jump in the magnetization (corresponding to an infinite avalanche) decreases to zero. At this transition we find a diverging length scale, power-law distributions of noise (avalanches), and universal behavior. We expand the critical exponents about mean-field theory in 6{minus}{epsilon} dimensions. Using a mapping to the pure Ising model, we Borel sum the 6{minus}{epsilon} expansion to {ital O}({epsilon}{sup 5}) for the correlation length exponent. We have developed a method for directly calculating avalanche distribution exponents, which we perform to {ital O}({epsilon}). Our analytical predictions agree with numerical exponents in two, three, four, and five dimensions [Perkovi{acute c} {ital et} {ital al}., Phys. Rev. Lett. {bold 75}, 4528 (1995)]. {copyright} {ital 1996 The American Physical Society.}

Dahmen, K.; Sethna, J.P. [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501 (United States)

1996-06-01

327

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

328

Loops in twistor space  

SciTech Connect

We elucidate the one-loop twistor-space structure corresponding to momentum-space maximally helicity-violating diagrams. We also discuss the infrared divergences, and argue that only a limited set of maximally helicity-violating diagrams contain them. We show how to introduce a twistor-space regulator corresponding to dimensional regularization for the infrared-divergent diagrams. We also evaluate explicitly the 'holomorphic anomaly' pointed out by Cachazo, Svrcek, and Witten, and use the result to define modified differential operators which can be used to probe the twistor-space structure of one-loop amplitudes.

Bena, Iosif; Bern, Zvi; Kosower, David A.; Roiban, Radu [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States); Service de Physique Theorique, CEA-Saclay F-91191 Gif-sur-Yvette cedex (France); Department of Physics, University of California, Santa Barbara, California 93106 (United States) and Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2005-05-15

329

Smart feedback loops  

NASA Astrophysics Data System (ADS)

It is necessary to find the golden mean in allocating the processing resources of a computer control system. Traditionally, feedback loops operate at the lower levels to ensure safe and stable operation of the accelerator. At present we use analogue and digital feedback loops. Some systems, such as the RF, require more complex algorithms. A possible way of providing these, using digital signal processors is described. The results of tests with the Race-Track Microtron Linac are given and the sources of the main internal and external disturbances have been analysed.

Chepurnov, A. S.; Gribov, I. V.; Gudkov, K. A.; Shumakov, A. V.; Shvedunov, V. I.

1994-12-01

330

Resistive hysteresis and capacitance effect in NiFe2O4/SrTiO3: Nb(1 wt%) junctions  

NASA Astrophysics Data System (ADS)

Epitaxial ultrathin NiFe2O4 films were deposited on 1 wt% Nb-doped SrTiO3 (0 0 1) substrates by reactive cosputtering to form junctions with an area of ˜2 mm2, and current-voltage curves show rectifying and asymmetrical hysteresis characteristics. The resistance calculated from the current-voltage curves is strongly voltage dependent, and the hysteretic loops with high and low resistive states were observed. The hysteretic loops are considered to stem from the capacitance effect of the highly resistive NiFe2O4 layer, which leads to charge accumulation at the interfaces. The results show that the interfaces of the junctions have a large areal capacitance of ˜100 nF/mm2 from 300 to 120 K.

Jin, C.; Jiang, E. Y.; Bai, H. L.

2011-08-01

331

Length Distributions in Loop Soups  

NASA Astrophysics Data System (ADS)

Statistical lattice ensembles of loops in three or more dimensions typically have phases in which the longest loops fill a finite fraction of the system. In such phases it is natural to ask about the distribution of loop lengths. We show how to calculate moments of these distributions using CPn-1 or RPn-1 and O(n) ? models together with replica techniques. The resulting joint length distribution for macroscopic loops is Poisson-Dirichlet with a parameter ? fixed by the loop fugacity and by symmetries of the ensemble. We also discuss features of the length distribution for shorter loops, and use numerical simulations to test and illustrate our conclusions.

Nahum, Adam; Chalker, J. T.; Serna, P.; Ortuño, M.; Somoza, A. M.

2013-09-01

332

Closing the Loop Sampler.  

ERIC Educational Resources Information Center

Closing the Loop (CTL) is a science curriculum designed to introduce students to integrated waste management through awareness. This document presents five lesson plans focusing on developing an understanding of natural resources, solid wastes, conservation, and the life of landfills. Contents include: (1) "What Are Natural Resources?"; (2)…

California Integrated Waste Management Board, Sacramento.

333

The inverse loop transform  

Microsoft Academic Search

The loop transform in quantum gauge field theory can be recognized as the Fourier transform (or characteristic functional) of a measure on the space of generalized connections modulo gauge transformations. Since this space is a compact Hausdorff space, conversely, we know from the Riesz-Markov theorem that every positive linear functional on the space of continuous functions thereon qualifies as the

Thomas Thiemann; Max Planck

1998-01-01

334

Isotropic loop quantum cosmology  

Microsoft Academic Search

Isotropic models in loop quantum cosmology allow explicit calculations, thanks largely to a completely known volume spectrum, which is exploited in order to write down the evolution equation in a discrete internal time. Because of genuinely quantum geometrical effects, the classical singularity is absent in those models in the sense that the evolution does not break down there, contrary to

Martin Bojowald

2002-01-01

335

Flowcharting loops without cycles  

Microsoft Academic Search

In spite of recent progress in software engineering, many programmers continue to use flowcharting techniques which hamper rather than enhance their ability to create structured programs. This paper describes some of the problems of representing loops with existing techniques and suggests an alternative which solves these problems. The ideas presented here are meant to deal with some of the same

N. H. Weiderman; B. M. Rawson

1975-01-01

336

Loop effects in ?-->?+?-?  

NASA Astrophysics Data System (ADS)

We show that the incorporation of the model consisting of a loop of charged kaons in the description of the ?-->ƒ;0? decay has important effects on the expected signal to background ratio for e+e--->?(?)-->?+?-?. On leave of absence from Escuela Ciencias Físico-Matemáticas, Universidad Autónoma de Sinaloa.

Lucio, J. L. M.; Napsuciale, M.

1994-07-01

337

Closing the Loop Sampler.  

ERIC Educational Resources Information Center

|Closing the Loop (CTL) is a science curriculum designed to introduce students to integrated waste management through awareness. This document presents five lesson plans focusing on developing an understanding of natural resources, solid wastes, conservation, and the life of landfills. Contents include: (1) "What Are Natural Resources?"; (2)…

California Integrated Waste Management Board, Sacramento.

338

Mashup the OODA Loop.  

National Technical Information Service (NTIS)

This paper provides an overview of several Web 2.0 applications and how they can be constructed via mashups to augment current Army Command and Control (C2) processes via the Observe, Orient, Decide, and Act (OODA) Loop concept. As defined by Wikipedia, a...

J. E. Heier

2008-01-01

339

Loop heat pipes  

Microsoft Academic Search

Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several

Yu. F. Maydanik

2005-01-01

340

OMR DEGASIFIER LOOP EXPERIMENT  

Microsoft Academic Search

A loop was constructed to study the removal of water and highly volatile ; materials from Organic Moderated Reactor coolaint by vacuum degasification. An ; analysis of the process was made to determine the effects of pressure, feed rate, ; nozzle pressure drop, and temperature upon degasification efficiency. The rate ; of degasification was quite sensitive to pressure. The other

G. W. Corporales; P. R. Benson

1960-01-01

341

Loop models with crossings  

NASA Astrophysics Data System (ADS)

The universal behavior of two-dimensional loop models can change dramatically when loops are allowed to cross. We study models with crossings both analytically and with extensive Monte Carlo simulations. Our main focus (the “completely packed loop model with crossings”) is a simple generalization of well-known models that shows an interesting phase diagram with continuous phase transitions of a new kind. These separate the unusual “Goldstone” phase observed previously from phases with short loops. Using mappings to Z2 lattice gauge theory, we show that the continuum description of the model is a replica limit of the ? model on real projective space (RPn-1). This field theory sustains Z2 point defects, which proliferate at the transition. In addition to studying the new critical points, we characterize the universal properties of the Goldstone phase in detail, comparing renormalization group (RG) calculations with numerical data on systems of linear size up to L=106 at loop fugacity n=1. (Very large sizes are necessary because of the logarithmic form of correlation functions and other observables.) The model is relevant to polymers on the verge of collapse, and a particular point in parameter space maps to self-avoiding trails at their ? point; we use the RG treatment of a perturbed ? model to resolve some perplexing features in the previous literature on trails. Finally, one of the phase transitions considered here is a close analog of those in disordered electronic systems—specifically, Anderson metal-insulator transitions—and provides a simpler context in which to study the properties of these poorly understood (central-charge-zero) critical points.

Nahum, Adam; Serna, P.; Somoza, A. M.; Ortuño, M.

2013-05-01

342

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

SciTech Connect

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

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

1992-01-01

343

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

344

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

345

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

346

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

347

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

348

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

349

A Numerical Study of Hysteresis as Observed at the Watershed Scale  

NASA Astrophysics Data System (ADS)

Thorough understanding of the behavior of saturated source areas is essential for accurate distributed hydrologic modeling of watersheds with shallow, highly pervious soils. The objective of this research is to explore the relationship that physically based small hypothetical watershed properties have on the temporal evolution and decay of saturated surface area. A homogenous, open-book shaped catchment with constant hillslope is chosen for testing due to it's simple geometry and ease of parameter variation. The use of a new physics-based hydrologic model, The Sandbox Model, is used to evaluate saturated area response to characteristic changes in a hypothetical watershed. The Sandbox model development is conceptualized after the rainfall-runoff experimental facility constructed and operated by V.T. Chow and B.C. Yen at the University of Illinois in the late 1960's. The use of a physics-based, distributed model can help simplify measurements of baseflow and interflow contributions to total runoff which are traditionally difficult, expensive, and subject to uncertain interpretation. A thorough sensitivity analysis is undertaken to evaluate model response to variations in state parameters. Sandbox model output is compared to a popular semi-distributed model, TOPMODEL [Beven, 1979], to further evaluate model performance and overall formulation. The hypothetical watershed time to equilibrium is calculated for several unique watershed configurations to examine watershed characteristic response. Plotting the temporal pathways of the watershed's wetting and drying cycles shows a wide variety of trajectories or hysteretic loops. Further, a parametric analysis is used to quantify the impact and magnitude of hypothetical catchment properties on hysteresis, seen as watershed-scale saturated area verse basin-average water content. Sensitivity analysis shows that the model is most sensitive to changes in saturated hydraulic conductivity and the constant depth to bedrock parameter. Time to equilibrium asymptotically approaches a minimum value for all input parameters and values that shifts upward or downward with different parameter values. Changes in saturated hydraulic conductivity exhibits the widest response when computing the maximum envelope volume of watershed hysteretic loops. Quantification of the watershed hysteretic loops reveal interactions between watershed slopes that produce local maxima at 5.0% for side slope and 2.5% for valley slopes.

Niedzialek, J. M.; Ogden, F. L.

2002-12-01

350

COLD TEST LOOP INTEGRATED TEST LOOP RESULTS  

SciTech Connect

A testing facility (Cold Test Loop) was constructed and operated to demonstrate the efficacy of the Accelerated Waste Retrieval (AWR) Project's planned sluicing approach to the remediation of Silos 1 and 2 at the Fernald Environmental Management Project near Cincinnati, Ohio. The two silos contain almost 10,000 tons of radium-bearing low-level waste, which consists primarily of solids of raffinates from processing performed on ores from the Democratic Republic of Congo (commonly referred to as ''Belgium Congo ores'') for the recovery of uranium. These silos are 80 ft in diameter, 36 ft high to the center of the dome, and 26.75 ft to the top of the vertical side walls. The test facility contained two test systems, each designed for a specific purpose. The first system, the Integrated Test Loop (ITL), a near-full-scale plant including the actual equipment to be installed at the Fernald Site, was designed to demonstrate the sluicing operation and confirm the selection of a slurry pump, the optimal sluicing nozzle operation, and the preliminary design material balance. The second system, the Component Test Loop (CTL), was designed to evaluate many of the key individual components of the waste retrieval system over an extended run. The major results of the initial testing performed during July and August 2002 confirmed that the AWR approach to sluicing was feasible. The ITL testing confirmed the following: (1) The selected slurry pump (Hazleton 3-20 type SHW) performed well and is suitable for AWR application. However, the pump's motor should be upgraded to a 200-hp model and be driven by a 150-hp variable-frequency drive (VFD). A 200-hp VFD is not much more expensive and would allow the pump to operate at full speed. (2) The best nozzle performance was achieved by using 15/16-in. nozzles operated alternately. This configuration appeared to most effectively mine the surrogate. (3) The Solartron densitometer, which was tested as an alternative mass flow measurement device, did not operate effectively. Consequently, it is not suitable for application to the AWR process. (4) Initially, the spray ring (operated at approximately 2300 psi) and the nozzles provided by the pump vendor did not perform acceptably. The nozzles were replaced with a more robust model, and the performance was then acceptable. (5) The average solids concentration achieved in the slurry before Bentogrout addition was approximately 16% by weight. The solids concentration of the slurry after Bentogrout addition ranged from 26% to approximately 40%. The slurry pump and ITL system performed well at every concentration. No line plugging or other problems were noted. The results of the CTL runs and later ITL testing are summarized in an appendix to this report.

Abraham, TJ

2003-10-22

351

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

352

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

353

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

354

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

355

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

356

Long-term soil moisture variability from a new P-E water budget method  

NASA Astrophysics Data System (ADS)

Basin-scale soil moisture is traditionally estimated using either land-surface model forced by observed meteorological variables or atmospheric moisture convergence from atmospheric analysis and observed runoff. Interannual variability from such methods suffer from major uncertainties due to the sensitivity to small imperfections in the land-surface model or the atmospheric analysis. Here we introduce a novel P-E method in estimating basin-scale soil moisture, or more precisely apparent land water storage (AWS). The key input variables are observed precipitation and runoff, and reconstructed evaporation. We show the results for the tropics using the example of the Amazon basin. The seasonal cycle of diagnosed soil moisture over the Amazon is about 200mm, compares favorably with satellite estimate from the GRACE mission, thus lending confidence both in this method and the usefulness of space gravity based large-scale soil moisture estimate. This is about twice as large as estimates from several traditional methods, suggesting that current models tend to under estimate the soil moisture variability. One of the advantage of the P-E method is to retrive long-term variability of the basin-scale soil moisture (including interannual and decadal time scales), which can provide valuable information to understand climate variability and to predict future climate condition. However, validation on reconstructed evaporation is very difficult due to lack of observation. The interannual variability in AWS in the Amazon basin is about 150mm, also consistent with GRACE data, but much larger than model results. We also apply this P-E method to the midlatitude Mississippi basin and discuss the impact of major 20th century droughts such as the dust bowl period on the long-term soil moisture variability. The results suggest the existence of soil moisture memories on decadal time scales, significantly longer than typically assumed seasonal timescales.

Zeng, N.; Yoon, J.; Mariotti, A.; Swenson, S. C.

2006-05-01

357

First Measurement of Transferred Polarization in the Exclusive e-->p-->e'K+Lambda> Reaction  

Microsoft Academic Search

The first measurements of the transferred polarization for the exclusive e-->p-->e'K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV\\/c)2, W from 1.6 to 2.15GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong

Daniel S. Carman; K. Joo; M. D. Mestayer; B. A. Raue; G. Adams; P. Ambrozewicz; E. Anciant; M. Anghinolfi; D. S. Armstrong; B. Asavapibhop; G. Audit; T. Auger; H. Avakian; H. Bagdasaryan; J. P. Ball; S. P. Barrow; M. Battaglieri; K. Beard; M. Bektasoglu; M. Bellis; C. Bennhold; N. Bianchi; A. S. Biselli; S. Boiarinov; B. E. Bonner; S. Bouchigny; R. Bradford; D. Branford; W. J. Briscoe; W. K. Brooks; V. D. Burkert; C. Butuceanu; J. R. Calarco; B. Carnahan; A. Cazes; C. Cetina; L. Ciciani; R. Clark; P. L. Cole; A. Coleman; D. Cords; P. Corvisiero; D. Crabb; H. Crannell; J. P. Cummings; E. Desanctis; P. V. Degtyarenko; H. Denizli; L. Dennis; R. Devita; K. V. Dharmawardane; K. S. Dhuga; C. Djalali; G. E. Dodge; D. Doughty; P. Dragovitsch; M. Dugger; S. Dytman; O. P. Dzyubak; M. Eckhause; H. Egiyan; K. S. Egiyan; L. Elouadrhiri; A. Empl; P. Eugenio; R. Fatemi; G. Fedotov; R. J. Feuerbach; J. Ficenec; T. A. Forest; H. Funsten; S. J. Gaff; M. Gai; M. Garçon; G. Gavalian; S. Gilad; G. P. Gilfoyle; K. L. Giovanetti; P. Girard; E. Golovach; C. I. Gordon; K. Griffioen; S. Grimes; M. Guidal; M. Guillo; L. Guo; V. Gyurjyan; C. Hadjidakis; R. S. Hakobyan; J. Hardie; D. Heddle; P. Heimberg; F. W. Hersman; K. Hicks; R. S. Hicks; M. Holtrop; J. Hu; C. E. Hyde-Wright; B. Ishkhanov; M. M. Ito; D. Jenkins; J. H. Kelley; J. D. Kellie; M. Khandaker; K. Y. Kim; W. Kim; A. Klein; F. J. Klein; A. V. Klimenko; M. Klusman; M. Kossov; L. H. Kramer; Y. Kuang; S. E. Kuhn; J. Kuhn; J. Lachniet; J. M. Laget; D. Lawrence; J. Li; K. Livingston; A. Longhi; K. Lukashin; J. J. Manak; C. Marchand; T. Mart; S. McAleer; J. McCarthy; J. W. McNabb; B. A. Mecking; S. Mehrabyan; J. J. Melone; C. A. Meyer; K. Mikhailov; R. Minehart; M. Mirazita; R. Miskimen; V. Mokeev; L. Morand; S. A. Morrow; M. U. Mozer; V. Muccifora; J. Mueller; L. Y. Murphy; G. S. Mutchler; J. Napolitano; R. Nasseripour; S. O. Nelson; S. Niccolai; G. Niculescu; I. Niculescu; B. B. Niczyporuk; R. A. Niyazov; M. Nozar; G. V. O'Rielly; A. K. Opper; M. Osipenko; K. Paschke; E. Pasyuk; G. Peterson; N. Pivnyuk; D. Pocanic; O. Pogorelko; E. Polli; S. Pozdniakov; B. M. Preedom; J. W. Price; Y. Prok; D. Protopopescu; L. M. Qin; G. Riccardi; G. Ricco; M. Ripani; B. G. Ritchie; F. Ronchetti; P. Rossi; D. Rowntree; P. Rubin; F. Sabatié; K. Sabourov; C. Salgado; J. Santoro; V. Sapunenko; R. A. Schumacher; V. S. Serov; Y. G. Sharabian; J. Shaw; S. Simionatto; A. V. Skabelin; E. S. Smith; L. C. Smith; D. I. Sober; M. Spraker; A. Stavinsky; S. Stepanyan; P. Stoler; M. Taiuti; S. Taylor; D. J. Tedeschi; U. Thoma; R. Thompson; L. Todor; C. Tur; M. Ungaro; M. F. Vineyard; A. V. Vlassov; K. Wang; L. B. Weinstein; H. Weller; D. P. Weygand; C. S. Whisnant; E. Wolin; M. H. Wood; A. Yegneswaran; J. Yun; B. Zhang; J. Zhao; Z. Zhou

2003-01-01

358

Closed loop control of heliostats  

Microsoft Academic Search

Tracking control in current heliostats is performed with an open loop, without any verification that the radiation is actually arriving at the desired target. Errors due to open-loop tracking control are often around 1–2 mrad and can accumulate during operation. A significant reduction of tracking error by closing the control loop is presented. The method includes a dynamic measurement of

Abraham Kribus; Irina Vishnevetsky; Amnon Yogev; Tatiana Rubinov

2004-01-01

359

Service in a Loop System  

Microsoft Academic Search

The statistical behavior of a loop service system is studied. The system consists of a main station, a server and N stations arranged on a loop. Customers arrive at each station according to a random process. The server makes successive tours along the loop bringing customers from the N stations to the main station. Two related measures of the grade

Alan G. Konheim; Bernd Meister

1972-01-01

360

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

361

Getting Your Loops Straight  

NSDL National Science Digital Library

This article introduces a special issue on the study of biochemical signaling pathways. Complicated biochemical signaling pathways regulate the function of living cells. Such regulatory networks often have âÂÂdownstreamâ components that provide input to components that act earlier in a pathway, creating feedback loops. These feedback loops have the potential to greatly alter the properties of a pathway and how it responds to stimuli. To fully understand these regulatory systems and exploit their vast potential as targets of therapeutic strategies, we need quantitative information on the flow of signals through a pathway and on the timing and location of signaling events within cells. The papers assembled in this special issue and in the companion issue of Science Signaling highlight recent progress in tackling these challenges.

L. Bryan Ray (AAAS;)

2008-10-17

362

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

363

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

364

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

365

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

366

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

367

Closing the loop.  

PubMed

The dream of closing the loop is actually the dream of creating an artificial pancreas and freeing the patients from being involved with the care of their own diabetes. Insulin-dependent diabetes (type 1) is a chronic incurable disease which requires constant therapy without the possibility of any 'holidays' or insulin-free days. It means that patients have to inject insulin every day of their life, several times per day, and in order to do it safely they also have to measure their blood glucose levels several times per day. Patients need to plan their meals, their physical activities and their insulin regime - there is only very small room for spontaneous activities. This is why the desire for an artificial pancreas is so strong despite the fact that it will not cure the diabetic patients. Attempts to develop a closed-loop system started in the 1960s but never got to a clinical practical stage of development. In recent years the availability of continuous glucose sensors revived those efforts and stimulated the clinician and researchers to believe that closing the loop might be possible nowadays. Many papers have been published over the years describing several different ideas on how to close the loop. Most of the suggested systems have a sensing arm that measures the blood glucose repeatedly or continuously, an insulin delivery arm that injects insulin upon command and a computer that makes the decisions of when and how much insulin to deliver. The differences between the various published systems in the literature are mainly in their control algorithms. However, there are also differences related to the method and site of glucose measurement and insulin delivery. SC glucose measurements and insulin delivery are the most studied option but other combinations of insulin measurements and glucose delivery including intravascular and intraperitoneal (IP) are explored. We tried to select recent publications that we believe had influenced and inspired people interested in the field. PMID:20377660

Dassau, E; Atlas, E; Phillip, M

2010-02-01

368

Chemical Looping Combustion Kinetics  

SciTech Connect

One of the most promising methods of capturing CO{sub 2} emitted by coal-fired power plants for subsequent sequestration is chemical looping combustion (CLC). A powdered metal oxide such as NiO transfers oxygen directly to a fuel in a fuel reactor at high temperatures with no air present. Heat, water, and CO{sub 2} are released, and after H{sub 2}O condensation the CO{sub 2} (undiluted by N{sub 2}) is ready for sequestration, whereas the nickel metal is ready for reoxidation in the air reactor. In principle, these processes can be repeated endlessly with the original nickel metal/nickel oxide participating in a loop that admits fuel and rejects ash, heat, and water. Our project accumulated kinetic rate data at high temperatures and elevated pressures for the metal oxide reduction step and for the metal reoxidation step. These data will be used in computational modeling of CLC on the laboratory scale and presumably later on the plant scale. The oxygen carrier on which the research at Utah is focused is CuO/Cu{sub 2}O rather than nickel oxide because the copper system lends itself to use with solid fuels in an alternative to CLC called 'chemical looping with oxygen uncoupling' (CLOU).

Edward Eyring; Gabor Konya

2009-03-31

369

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

370

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

371

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

372

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

373

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

374

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

375

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

376

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

377

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

378

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

379

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

380

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

381

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

382

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

383

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

384

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

385

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

386

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

387

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

388

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

389

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

390

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

391

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

392

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

393

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

394

Loop diagrams without ? matrices  

NASA Astrophysics Data System (ADS)

By using a quantum-mechanical path integral to compute matrix elements of the form , radiative corrections in quantum-field theory can be evaluated without encountering loop-momentum integrals. In this paper we demonstrate how Dirac ? matrices that occur in the proper-time ``Hamiltonian'' H lead to the introduction of a quantum-mechanical path integral corresponding to a superparticle analogous to one proposed recently by Fradkin and Gitman. Direct evaluation of this path integral circumvents many of the usual algebraic manipulations of ? matrices in the computation of quantum-field-theoretical Green's functions involving fermions.

McKeon, D. G. C.; Rebhan, A.

1993-09-01

395

The Gulf Loop Current  

NSDL National Science Digital Library

Students conduct experiments and explore wind driven currents, determining patterns of current flow in a body of water. They participate in a relay where they blow a Styrofoam peanut or cotton ball across the classroom floor. They explore the motion of Styrofoam pieces that are floating in a clear pie pan of water simulating the Gulf Loop, and compare their pie pan model with a map of the currents. Students will map the trip of several different types of beach debris as it travels to the Texas coast.

Stryker, Pam

2010-01-01

396

Accelerating the loop expansion  

SciTech Connect

This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.

Ingermanson, R.

1986-07-29

397

Resultants and loop closure  

NASA Astrophysics Data System (ADS)

The problem of tripeptide loop closure is formulated in terms of the angles {?i} 3i=1 describing the orientation of each peptide unit about the virtual axis joining the C? atoms. Imposing the constraint that at the junction of two such units the bond angle between the bonds C??N and C??C is fixed at some prescribed value ? results in a system of three bivariate polynomials in ui ? tan ?i/2 of degree 2 in each variable. The system is analyzed for the existence of common solutions by making use of resultants, determinants of matrices composed of the coefficients of two (or more) polynomials, whose vanishing is a necessary and sufficient condition for the polynomials to have a common root. Two resultants are compared: the classical Sylvester resultant and the Dixon resultant. It is shown that when two of the variables are eliminated in favor of the third, a polynomial of degree 16 results. To each one of its real roots, there is a corresponding common zero of the system. To each such zero, there corresponds a consistent conformation of the chain. The Sylvester method can find these zeros among the eigenvalues of a 24 × 24 matrix. For the Dixon approach, after removing extraneous factors, an optimally sized eigenvalue problem of size 16 × 16 results. Finally, the easy extension to the more general problem of triaxial loop closure is presented and an algorithm for implementing the method on arbitrary chains is given.

Coutsias, Evangelos A.; Seok, Chaok; Wester, Michael J.; Dill, Ken A.

398

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

399

Doubly Excited 1,3 P e Resonance States of the Positronium Negative Ion with Coulomb and Screened Coulomb Potentials  

NASA Astrophysics Data System (ADS)

We have investigated the doubly excited 1,3 P e resonance states of positronium negative ion with Coulomb and screened Coulomb potentials using highly accurate correlated exponential wavefunctions. For Coulomb interaction, the stabilization and the complex-rotation methods are employed to extract resonance parameters (resonance positions and widths). We have obtained two 1 P e resonances and three 3 P e resonances below the n = 3 Ps threshold. In addition to Feshbach resonances lying below n = 3 Ps threshold, we have calculated one 3 P e shape resonances lying above the Ps ( n = 2) threshold. For screened Coulomb (Yukawa) interaction, we employ the stabilization method to extract resonance parameters as functions screening parameter. The resonance energies and widths for 1,3 P e resonance states of Ps- below the n = 3 Ps threshold for different screening parameters ranging from infinity (Coulomb case) to small values are reported, along with the Ps(3S) and Ps(3P) threshold energies. The screened Coulomb results for the 1,3 P e resonance states are reported for the first time in the literature.

Kar, Sabyasachi; Ho, Y. K.

2009-09-01

400

Unstable anisotropic loop quantum cosmology  

SciTech Connect

We study stability conditions of the full Hamiltonian constraint equation describing the quantum dynamics of the diagonal Bianchi I model in the context of loop quantum cosmology. Our analysis has shown robust evidence of an instability in the explicit implementation of the difference equation, implying important consequences for the correspondence between the full loop quantum gravity theory and loop quantum cosmology. As a result, one may question the choice of the quantization approach, the model of lattice refinement, and/or the role of the ambiguity parameters; all these should, in principle, be dictated by the full loop quantum gravity theory.

Nelson, William; Sakellariadou, Mairi [Department of Physics, King's College London, Strand WC2R 2LS, London (United Kingdom)

2009-09-15

401

Experimental study of a two-phase thermosiphon-loop heat exchanger  

SciTech Connect

An experimental study of the performance of an air-to-air, multi-loop, two-phase thermosiphon heat-exchanger system, utilizing R-11 as the working fluid, has been carried out to investigate the effect of its previous thermal history for hot air to cold air temperature differences up to 50 Celsius degrees. Tests were run on a four loop system with equal face velocities of 1.3, 2.2 and 3.1 m/s at each coil and on a single loop system with a face velocity of 2.2 m/s. An hysterisis loop was found to exist on each plot of heat-exchanger effectiveness vs. overall temperature difference for temperature differences below 45 Celsius degrees. Boiling was not initiated until a difference of 13 degrees was reached. However, once initiated, boiling was not completely stopped until the temperature difference dropped below 4 degrees. The shape of the two bounding curves which form these hysteresis loops could be approximated very well by exponential curves.

Stauder, F.A.; McDonald, T.W.

1986-01-01

402

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

403

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

404

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

405

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

406

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

407

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

408

Loop-the-Loop: Bringing Theory into Practice  

ERIC Educational Resources Information Center

|During the Thai high-school physics teacher training programme, we used an aluminum loop-the-loop system built by the Institute for the Promotion of Teaching Science and Technology (IPST) to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. There were 27 high-school teachers from three provinces,…

Suwonjandee, N.; Asavapibhop, B.

2012-01-01

409

Loop-the-Loop: Bringing Theory into Practice  

ERIC Educational Resources Information Center

During the Thai high-school physics teacher training programme, we used an aluminum loop-the-loop system built by the Institute for the Promotion of Teaching Science and Technology (IPST) to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. There were 27 high-school teachers from three provinces,…

Suwonjandee, N.; Asavapibhop, B.

2012-01-01

410

Loop-the-Loop: An Easy Experiment, A Challenging Explanation  

NASA Astrophysics Data System (ADS)

A loop-the-loop built by the Institute for the Promotion of Teaching Science and Technology (IPST) was used in Thai high school teachers training program to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. We took videos using high speed camera to record the motions of a spherical steel ball moving down the aluminum inclined track at different released positions. The ball then moved into the circular loop and underwent a projectile motion upon leaving the track. We then asked the teachers to predict the landing position of the ball if we changed the height of the whole loop-the-loop system. We also analyzed the videos using Tracker, a video analysis software. It turned out that most teachers did not realize the effect of the friction between the ball and the track and could not obtain the correct relationship hence their predictions were inconsistent with the actual landing positions of the ball.

Asavapibhop, B.; Suwonjandee, N.

2010-07-01

411

Phase-Locked Loops  

NSDL National Science Digital Library

Phase-locked loops (PLL) are unique feedback control circuits that offer many useful features and benefits in electronic applications. PLLs are available either in integrated circuit (IC) form for general applications or built into larger system IC chips. Today, PLLs are found in virtually all types of electronic equipment from PCs to consumer products like TV sets and cell phones. This module provides an introduction to the PLL and its applications. It begins with an overview of the main components of a PLL and how these components work together. It then describes PLL specifications and a description of the most widely used applications including frequency synthesizers, clock multipliers, clock and data recovery circuits, FM demodulators, and filters.

2012-09-06

412

Uranyl Nitrate Flow Loop  

SciTech Connect

The objectives of the work discussed in this report were to: (1) develop a flow loop that would simulate the purified uranium-bearing aqueous stream exiting the solvent extraction process in a natural uranium conversion plant (NUCP); (2) develop a test plan that would simulate normal operation and disturbances that could be anticipated in an NUCP; (3) use the flow loop to test commercially available flowmeters for use as safeguards monitors; and (4) recommend a flowmeter for production-scale testing at an NUCP. There has been interest in safeguarding conversion plants because the intermediate products [uranium dioxide (UO{sub 2}), uranium tetrafluoride (UF{sub 4}), and uranium hexafluoride (UF{sub 6})] are all suitable uranium feedstocks for producing special nuclear materials. Furthermore, if safeguards are not applied virtually any nuclear weapons program can obtain these feedstocks without detection by the International Atomic Energy Agency (IAEA). Historically, IAEA had not implemented safeguards until the purified UF{sub 6} product was declared as feedstock for enrichment plants. H. A. Elayat et al. provide a basic definition of a safeguards system: 'The function of a safeguards system on a chemical conversion plant is in general terms to verify that no useful nuclear material is being diverted to use in a nuclear weapons program'. The IAEA now considers all highly purified uranium compounds as candidates for safeguarding. DOE is currently interested in 'developing instruments, tools, strategies, and methods that could be of use to the IAEA in the application of safeguards' for materials found in the front end of the nuclear fuel cycle-prior to the production of the uranium hexafluoride or oxides that have been the traditional starting point for IAEA safeguards. Several national laboratories, including Oak Ridge, Los Alamos, Lawrence Livermore, and Brookhaven, have been involved in developing tools or techniques for safeguarding conversion plants. This study was sponsored by the U.S. Department of Energy (DOE) NA-241, Office of Dismantlement and Transparency.

Ladd-Lively, Jennifer L [ORNL

2008-10-01

413

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders  

Microsoft Academic Search

Solder joints in electronic assemblies are typically subjected to thermal cycling, either in actual application or in accelerated life testing used for qualification. Mismatches in the thermal expansion coefficients of the assembly materials leads to the solder joints being subjected to cyclic (positive\\/negative) mechanical strains and stresses. This cyclic loading leads to thermomechanical fatigue damage that involves damage accumulation, crack

Muhannad Mustafa; Zijie Cai; Jeffrey C. Suhling; Pradeep Lall

2011-01-01

414

Exchange bias and anomalous vertical shift of the hysteresis loops in milled Fe\\/MnO 2 material  

Microsoft Academic Search

The present article reports studies on structural and magnetic properties of nanostructured Fe\\/MnO2 materials prepared by mechanosynthesis method, with Fe to MnO2 ratios of 20\\/80, 50\\/50 and 60\\/40. X-ray diffraction patterns indicate that the milled materials have crystalline grain size in the nanoscale region. Mössbauer spectra of the milled materials suggest the presence of two Fe phases for each sample:

E. C. Passamani; C. Larica; C. Marques; J. R. Proveti; A. Y. Takeuchi; F. H. Sanchez

2006-01-01

415

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

416

Computer simulation of feedback loops  

Microsoft Academic Search

The effect of the sampling rate on the behavior of computer simulated phase locked loops (PLL) is studied. The choice of integrators used in feedback systems is also analyzed. The performance degradation of the first order loop is obtained analytically, and verified by simulation on the Block Oriented Systems Simulator, BOSS. A bound on the allowable sampling rate is obtained

J. Fernandez; B. Hinton; J. Holtzman

1990-01-01

417

The Projectile Inside the Loop  

ERIC Educational Resources Information Center

|The loop-the-loop demonstration can be easily adapted to study the kinematics of projectile motion, when the moving body falls inside the apparatus. Video capturing software can be used to reveal peculiar geometrical effects of this simple but educational experiment.|

Varieschi, Gabriele U.

2006-01-01

418

The projectile inside the loop  

NASA Astrophysics Data System (ADS)

The loop-the-loop demonstration can be easily adapted to study the kinematics of projectile motion, when the moving body falls inside the apparatus. Video capturing software can be used to reveal peculiar geometrical effects of this simple but educational experiment.

Varieschi, Gabriele U.

2006-03-01

419

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

420

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

421

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

422

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

423

Experimental and computer simulation study of an air-to-air two-phase thermsiphon-loop heat-exchanger  

SciTech Connect

The effectiveness of an R-11, air-to-air, two-phase thermosiphon loop heat exchanger, has been simulated and compared to experimentally measured values. The effect of the coil face velocity and overall temperature difference on the system performance was investigated. For overall temperature differences less than 40 Celcius degrees, the past history of the heated surface can have a significant effect on the performance. Wall superheats of approximately 13 C were required to initiate boiling in the copper tubes. However, once nucleation sites were established, boiling could be sustained until the overall temperature difference decreased to approximately 4 Celcius degrees. This created an hysteresis envelope on an effectiveness versus overall temperature difference plot. The computer program developed was able to predict the performance of this system accurately for the cooling curve portion of the hysteresis curve. Further work is underway to simulate the heating portion of this curve.

Stauder, F.A.; Mathur, G.D.; McDonald, T.W.

1985-01-01

424

Heating of braided coronal loops  

NASA Astrophysics Data System (ADS)

Aims: We investigate the relaxation of braided magnetic loops in order to find out how the type of braiding via footpoint motions affects resultant heating of the loop. Methods: Two magnetic loops, braided in different ways, are used as initial conditions in resistive MHD simulations and their subsequent evolution is studied. Results: The fields both undergo a resistive relaxation in which current sheets form and fragment and the system evolves towards a state of lower energy. In one case this relaxation is very efficient with current sheets filling the volume and homogeneous heating of the loop occurring. In the other case fewer current sheets develop, less magnetic energy is released in the process and a patchy heating of the loop results. The two cases, although very similar in their setup, can be distinguished by the mixing properties of the photospheric driver. The mixing can be measured by the topological entropy of the plasma flow, an observable quantity.

Wilmot-Smith, A. L.; Pontin, D. I.; Yeates, A. R.; Hornig, G.

2011-12-01

425

The new booster synchronization loop  

SciTech Connect

The AGS Booster must be synchronized to the AGS rf system before bunch-to-bucket transfer of the beam. The Booster delivers four batches at 7.5 Hz and extraction occurs at full acceleration rate, leaving only 5 ms available for synchronization. An improvement has been made to the synchronization feedback loop. A new loop compensator has been designed using a state variable representation. The three state variables are, beam phase and frequency, and the reference input to the beam control phase loop. The design uses linear quadratic optimum control to achieve greater stability and smaller errors. Lock acquisition, without a transient, is accomplished by a circuit that derives the loop reference from the instantaneous state variable feedback value at loop closing. The reference is brought adiabatically to zero at transfer.

Onillon, E.; Brennan, J.M. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.

1995-05-01

426

Coronal Loop detection and seismology  

NASA Astrophysics Data System (ADS)

Using a TRACE image with a bipolar active region and over one hundred distinguishable loops, we examine several current methods for automated coronal loop detection. Using the same TRACE image, several new approaches are also taken in an attempt to increase accuracy and completeness rates for the automated detection process. By means of these new methods the expectation is to achieve a higher degree of completeness while maintaining a high level of accuracy in the detection process. To increase completeness, an automated attempt for the reconnection between orphaned loop segments will also be tested. In the future, an approach to reconstruction of three-dimensional images from several two-dimensional images can be devised by using the detected coronal loops and a known 3D offset of each image. However this process heavily depends on the ability to accurately and completely detect the coronal loops.

Pevtsov, Alexander; McAteer, R. T. J.; Jackiewicz, J.; Kirk, M.; McNamara, B.; DeGrave, K.; Amani Al-Ghraibah, A.; Boucheron, L.; Voelz, D.; Cao, H.; Taylor, G.

2011-05-01

427

Coronal Loop detection and seismology  

NASA Astrophysics Data System (ADS)

Using a TRACE image with a bipolar active region and over one hundred distinguishable loops, we examine several current methods for automated coronal loop detection. Using the same TRACE image, several new approaches are also taken in an attempt to increase accuracy and completeness rates for the automated detection process. These new methods are applied to AIA data from the Solar Dynamic Observatory with the expectation to achieve a higher degree of completeness while maintaining a high level of accuracy in the detection process. To increase completeness, an automated attempt for the reconnection between orphaned loop segments will also be tested. In the future, an approach to reconstruction of three-dimensional images from several two-dimensional images can be devised by using the detected coronal loops and a known 3D offset of each image. However this process heavily depends on the ability to accurately and completely detect the coronal loops.

Pevtsov, Alexander; McAteer, R. T. J.; Jackiewicz, Jason; Calabro, Brandon; McNamara, Bernie

2011-10-01

428

Scaling of cosmic string loops  

SciTech Connect

We study the spectrum of loops as a part of a complete network of cosmic strings in flat spacetime. After a long transient regime, characterized by production of small loops at the scale of the initial conditions, it appears that a true scaling regime takes over. In this final regime the characteristic length of loops scales as 0.1t, in contrast to earlier simulations which found tiny loops. We expect the expanding-universe behavior to be qualitatively similar. If this expectation is correct, then the large loop sizes have important cosmological implications. In particular, the nucleosynthesis bound then becomes G{mu} < or approx. 10{sup -7}, much tighter than that obtained from earlier analyses.

Vanchurin, Vitaly; Olum, Ken D.; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States)

2006-09-15

429

Temperature Dependent Morphology of Untwisted Coronal Loops.  

National Technical Information Service (NTIS)

The morphology of slender coronal loops with an untwisted magnetic field is investigated. The specific shape of a loop is delineated through application of equations determining the local minor radius and loop curvature along its length. These equations f...

D. A. Garren J. Chen P. J. Cargill

1992-01-01

430

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

431

Wilson loops in minimal surfaces  

SciTech Connect

The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS{sub 5} x S{sup 5}. The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS{sub 5} x S{sup 5} gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface.

Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

1999-04-27

432

Loop heat pipe radiator  

SciTech Connect

This paper describes the design and testing of a Loop Heat Pipe Radiator (LHPR) which was developed as an alternative to state-of-the-art axially-grooved heat pipes for space-based heat rejection which would be usable with tubing made of aluminum foil covered with a carbon-epoxy composite. The LHPR had an aluminum envelope and a polymer wick, and used ammonia as a working fluid. It was 4 meters long with a mass of 1.4 kg. The LHPR transported 500 watts at a 2.3 meter adverse inclination and 1500 watts when horizontal. This non-optimized LHPR had a 3000 watt-meter capability, which is four times greater than an axially-grooved heat pipe of similar power-handling capability and mass. In addition to a higher power handling capability, the LHPR has a much higher capillary margin than axially-grooved pipes. That high capillary margin simplifies ground testing in a 1-g environment by reducing the need for the careful levelling and vibration reduction required by axially-grooved pipes. {copyright} {ital 1996 American Institute of Physics.}

Sarraf, D.B.; Gernert, N.J. [Thermacore, Inc., 780 Eden Rd., Lancaster, Pennsylvania (United States)

1996-03-01

433

Modeling Loop Entropy  

PubMed Central

Proteins fold from a highly disordered state into a highly ordered one. Traditionally, the folding problem has been stated as one of predicting ‘the’ tertiary structure from sequential information. However, new evidence suggests that the ensemble of unfolded forms may not be as disordered as once believed, and that the native form of many proteins may not be described by a single conformation, but rather an ensemble of its own. Quantifying the relative disorder in the folded and unfolded ensembles as an entropy difference may therefore shed light on the folding process. One issue that clouds discussions of ‘entropy’ is that many different kinds of entropy can be defined: entropy associated with overall translational and rotational Brownian motion, configurational entropy, vibrational entropy, conformational entropy computed in internal or Cartesian coordinates (which can even be different from each other), conformational entropy computed on a lattice; each of the above with different solvation and solvent models; thermodynamic entropy measured experimentally, etc. The focus of this work is the conformational entropy of coil/loop regions in proteins. New mathematical modeling tools for the approximation of changes in conformational entropy during transition from unfolded to folded ensembles are introduced. In particular, models for computing lower and upper bounds on entropy for polymer models of polypeptide coils both with and without end constraints are presented. The methods reviewed here include kinematics (the mathematics of rigid-body motions), classical statistical mechanics and information theory.

Chirikjian, Gregory S.

2011-01-01

434

Unimodular loop quantum cosmology  

SciTech Connect

Unimodular gravity is based on a modification of the usual Einstein-Hilbert action that allows one to recover general relativity with a dynamical cosmological constant. It also has the interesting property of providing, as the momentum conjugate to the cosmological constant, an emergent clock variable. In this paper we investigate the cosmological reduction of unimodular gravity, and its quantization within the framework of flat homogeneous and isotropic loop quantum cosmology. It is shown that the unimodular clock can be used to construct the physical state space, and that the fundamental features of the previous models featuring scalar field clocks are reproduced. In particular, the classical singularity is replaced by a quantum bounce, which takes place in the same condition as obtained previously. We also find that requirement of semiclassicality demands the expectation value of the cosmological constant to be small (in Planck units). The relation to spin foam models is also studied, and we show that the use of the unimodular time variable leads to a unique vertex expansion.

Chiou, D.-W.; Geiller, Marc [Department of Physics, Beijing Normal University, Beijing 100875 (China); APC-Astroparticule et Cosmologie, Universite Paris Diderot Paris 7, Paris (France)

2010-09-15

435

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

436

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

437

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

438

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

439

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

440

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

441

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

442

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

443

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

444

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

445

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

446

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

447

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

448

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

449

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

450

Glueball masses and the loop-loop correlation functions  

Microsoft Academic Search

We analyse the pure gauge lattice QCD by measuring loop-loop correlation functions on a 123×32 lattice at beta=5.9. We select a set of operators given by the smearing procedure. We obtain a good estimate of the mass of the 0++ state and for the string tension, and upper bounds for the masses of the 2++ and the 1+- states.

M. Albanese; F. Costantini; G. Fiorentini; F. Flore; M. P. Lombardo; R. Tripiccione; P. Bacilieri; L. Fonti; E. Remiddi; M. Bernaschi; N. Cabibbo; L. A. Fernandez; E. Marinari; G. Parisi; G. Salina; S. Cabasino; F. Marzano; P. Paolucci; S. Petrarca; F. Rapuano; P. Marchesini; P. Giacomelli; R. Rusack

1987-01-01

451

Magnetic hysteresis of interface-biased flat iron dots  

NASA Astrophysics Data System (ADS)

We report a theoretical study of the coercivity and bias of iron dots exchange coupled with an antiferromagnetic substrate. We show that flat dots, with height close to the iron exchange length, and lateral dimensions of a few exchange lengths, exhibit large enhancement of coercivity and exchange bias. For small interface field strength the magnetization reversal is nearly a coherent rotation with symmetrical loops. Interface pinning leads to large reduction in coercivity and asymmetrical loops, if the interface field strength is comparable to the value of the iron exchange field. We discuss the impact of geometrical confinement and interface pinning on the magnetization reversal mechanisms. We show that small area dots with height larger than the exchange length display stronger interface effects.

Rebouças, G. O. G.; Silva, A. S. W. T.; Dantas, Ana L.; Camley, R. E.; Carriço, A. S.

2009-03-01

452

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

453

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

454

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

455

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

456

Application of the Preisach and Jiles{endash}Atherton models to the simulation of hysteresis in soft magnetic alloys  

SciTech Connect

This article describes the advances in unification of model descriptions of hysteresis in magnetic materials and demonstrates the equivalence of two widely accepted models, the Preisach (PM) and Jiles{endash}Atherton (JA) models. Recently it was shown that starting from general energy relations, the JA equation for a loop branch can be derived from PM. The unified approach is here applied to the interpretation of magnetization measured in nonoriented Si{endash}Fe steels with variable grain size {l_angle}s{r_angle}, and also in as-cast and annealed Fe amorphous alloys. In the case of NO Fe{endash}Si, the modeling parameter {ital k} defined by the volume density of pinning centers is such that k{approx}A+B/{l_angle}s{r_angle}, where the parameters {ital A} and {ital B} are related to magnetocrystalline anisotropy and grain texture. The value of {ital k} in the amorphous alloys can be used to estimate the microstructural correlation length playing the role of effective grain size in these materials. {copyright} {ital 1999 American Institute of Physics.}

Pasquale, M.; Bertotti, G. [IEN Galileo Ferraris and INFM, Corso Massimo DAzeglio 42, 10125 Torino (Italy); Jiles, D.C.; Bi, Y. [Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)

1999-04-01

457

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

458

On growth rate hysteresis and catastrophic crystal growth  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

459

Hysteresis in 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

460

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

461

Optical loop framing  

SciTech Connect

The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system.

Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.

1984-06-01

462

Magnetic Field from Loops Model  

NSDL National Science Digital Library

The EJSMagnetic Field from Loops model computes the B-field created by an electric current through a straight wire, a closed loop, and a solenoid. Users can adjust the vertical position of the slice through the 3D field. The Magnetic Field from Loops model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ntnu_MagneticFielfFromLoops.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang; Hwang, Fu-Kwun

2008-11-17

463

GENE LOOPS ENHANCE TRANSCRIPTIONAL DIRECTIONALITY  

PubMed Central

Eukaryotic genomes are extensively transcribed, forming both messenger (m) and noncoding (nc) RNAs. ncRNAs made by RNA polymerase II (Pol II) often initiate from bidirectional promoters (nucleosome-depleted chromatin) that synthesise mRNA and ncRNA in opposite directions. We demonstrate that actively transcribed mRNA encoding genes by adopting a gene loop conformation, restrict divergent transcription of ncRNAs. Since gene loop formation depends on a protein factor (Ssu72) that co-associates with both promoter and terminator, its inactivation leads to increased synthesis of promoter-associated divergent ncRNAs, referred to as Ssu72 restricted transcripts (SRT). Similarly, inactivation of individual gene loops by gene mutation enhances SRT synthesis. We demonstrate that gene loop conformation enforces transcriptional directionality on otherwise bidirectional promoters.

Tan-Wong, Sue Mei; Zaugg, Judith B.; Camblong, Jurgi; Xu, Zhenyu; Zhang, David W.; Mischo, Hannah E.; Ansari, Aseem Z.; Luscombe, Nicholas M.; Steinmetz, Lars M.; Proudfoot, Nick J.

2012-01-01

464

Wilson loops and spin networks  

NASA Astrophysics Data System (ADS)

If G is any finite product of orthogonal, unitary and symplectic matrix groups, then Wilson loops generate a dense subalgebra of continuous observables on the configuration space of lattice gauge theory with structure group G. If G is orthogonal, unitary or symplectic, then Wilson loops associated to the natural representation of G are enough. This extends a result of A. Sengupta [4]. In particular, our approach includes the case of even orthogonal groups.

Lévy, Thierry

2006-03-01

465

Loop quantum cosmology: Recent progress  

Microsoft Academic Search

Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like\\u000a cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to\\u000a the quantum regime. As a consequence, the structure of and the approach to classical singularities are very different from

Martin Bojowald

2004-01-01

466