Note: This page contains sample records for the topic hysteresis curve shows 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

Two opposite hysteresis curves in semiconductors with mobile dopants  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

2

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

3

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

4

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

Microsoft Academic Search

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

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

2001-01-01

5

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

6

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

7

Recruitability of the lung estimated by the pressure volume curve hysteresis in ARDS patients  

Microsoft Academic Search

Objective  To assess the hysteresis of the pressure–volume curve (PV curve) as to estimate, easily and at the bedside, the recruitability\\u000a of the lung in ARDS patients.\\u000a \\u000a \\u000a \\u000a Design  Prospective study.\\u000a \\u000a \\u000a \\u000a Setting  Twelve medico-surgical ICU beds of a general hospital.\\u000a \\u000a \\u000a \\u000a Patients  Twenty-six patients within the first 24 h from meeting ARDS criteria.\\u000a \\u000a \\u000a \\u000a Intervention  A Quasi-static inflation and deflation PV curve from 0 to 40 cmH2O and a 40 cmH2O

Didier Demory; Jean-Michel Arnal; Marc Wysocki; Stéphane Donati; Isabelle Granier; Gaëlle Corno; Jacques Durand-Gasselin

2008-01-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

9

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

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

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

10

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

11

Influence of experimental methods on crossing in magnetic force-gap hysteresis curve of HTS maglev system  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

12

14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING FALL RIVER ROAD RISING FROM BENEATH CHAPIN PASS (AT EXTREME RIGHT) TO FALL RIVER PASS (FAR LEFT). - Fall River Road, Between Estes Park & Fall River Pass, Estes Park, Larimer County, CO

13

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

14

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

15

Effect of the magnetic field applied during cooling on magnetic hysteresis in the low-temperature phase of magnetite: First-order reversal curve (FORC) analysis  

Microsoft Academic Search

The strength of a magnetic field applied during cooling through the Verwey transition can control the low-temperature (LT) magnetic hysteresis properties of magnetite. This effect is investigated using the first-order reversal curve (FORC) technique. LT FORC distributions were measured at 20 K from four polycrystalline samples after cooling from 300 K in zero magnetic field or in the presence of

A. V. Smirnov

2007-01-01

16

The Transcriptional Heat Shock Response of Salmonella Typhimurium Shows Hysteresis and Heated Cells Show Increased Resistance to Heat and Acid Stress  

PubMed Central

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

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

2012-01-01

17

The transcriptional heat shock response of Salmonella typhimurium shows hysteresis and heated cells show increased resistance to heat and acid stress.  

PubMed

We investigated if the transcriptional response of Salmonella Typhimurium to temperature and acid variations was hysteretic, i.e. whether the transcriptional regulation caused by environmental stimuli showed memory and remained after the stimuli ceased. The transcriptional activity of non-replicating stationary phase cells of S. Typhimurium caused by the exposure to 45 °C and to pH 5 for 30 min was monitored by microarray hybridizations at the end of the treatment period as well as immediately and 30 minutes after conditions were set back to their initial values, 25 °C and pH 7. One hundred and two out of 120 up-regulated genes during the heat shock remained up-regulated 30 minutes after the temperature was set back to 25 °C, while only 86 out of 293 down regulated genes remained down regulated 30 minutes after the heat shock ceased. Thus, the majority of the induced genes exhibited hysteresis, i.e., they remained up-regulated after the environmental stress ceased. At 25 °C the transcriptional regulation of genes encoding for heat shock proteins was determined by the previous environment. Gene networks constructed with up-regulated genes were significantly more modular than those of down-regulated genes, implying that down-regulation was significantly less synchronized than up-regulation. The hysteretic transcriptional response to heat shock was accompanied by higher resistance to inactivation at 50 °C as well as cross-resistance to inactivation at pH 3; however, growth rates and lag times at 43 °C and at pH 4.5 were not affected. The exposure to pH 5 only caused up-regulation of 12 genes and this response was neither hysteretic nor accompanied of increased resistance to inactivation conditions. Cellular memory at the transcriptional level may represent a mechanism of adaptation to the environment and a deterministic source of variability in gene regulation. PMID:23236453

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

2012-12-07

18

Venous Grafts Procured During the Learning Curve for Endoscopic Veins Harvesting Show Compromised Vascular Remodeling  

PubMed Central

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

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

2011-01-01

19

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

20

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

21

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

22

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

23

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

24

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

25

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

26

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

SciTech Connect

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

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

2004-03-12

27

[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

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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

39

On using high-order polynomial curve fits in the quasi-steady theory for square-cylinder galloping  

NASA Astrophysics Data System (ADS)

Quasi-steady theory shows that the galloping response of a square cylinder exhibits a hysteresis phenomenon. The equation of motion, which was derived based on a seventh-order polynomial curve fit on the side force (Cy) versus angle of attack (?) curve, shows that the number of positive real roots corresponds to the number of stationary oscillation amplitudes. In this investigation, we use polynomials of even higher order (ninth and eleventh) to curve fit the Cy versus ? curve, in an attempt to see if additional positive real roots occur, which may reveal even more flow physics. The results show that only extra negative real roots and/or complex roots are obtained when higher than seventh-order polynomial curve fits are used. Hence, the use of a seventh-order polynomial curve fit in the quasi-steady theory is shown to be sufficient in describing the flow physics which includes the prediction of the hysteresis phenomenon.

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

2005-01-01

40

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

41

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

42

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

43

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

44

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

45

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

46

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

47

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

48

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

49

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

50

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

51

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

52

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

53

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

54

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

55

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

56

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

NASA Astrophysics Data System (ADS)

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

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

1999-04-01

57

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

58

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

59

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

60

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

61

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

62

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

63

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

64

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

65

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

66

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

67

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

68

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

69

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

70

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

71

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

72

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

73

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

74

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

75

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

76

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

77

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

78

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

79

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

80

Nanomechanical Detection of Magnetic Hysteresis of a Single-crystal Yttrium Iron Garnet Micromagnetic Disk  

NASA Astrophysics Data System (ADS)

A micromagnetic disk was milled from a monocrystalline yttrium iron garnet film using a focused ion beam and micromanipulated onto a nanoscale torsional resonator. Nanomechanical torque magnetometry results show a unipolar magnetic hysteresis characteristic of a magnetic vortex state. Landau-Lifshitz-Gilbert-based micromagnetic simulations of the disk show a rich, flux-enclosed, three-dimensional domain structure. On the top and bottom faces of the disk, a skewed vortex state exists with a very small core. The core region extends through the thickness of the disk with a smooth variation in core diameter reaching a maximum along the midplane of the disk. The single crystalline nature of the disk lends to an observed absence of Barkhausen-like steps in the magnetization-versus-field curves, qualitatively different in comparison to the magnetometry results of an individual polycrystalline permalloy microdisk. Prospects for the mechanical detection of spin dynamical modes in these structures will also be discussed.

Losby, Joseph; Diao, Zhu; Burgess, Jacob; Compton, Shawn; Fani Sani, Fatemeh; Firdous, Tayyaba; Vick, Douglas; Belov, Miro; Hiebert, Wayne; Freeman, Mark

2013-03-01

81

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

82

Frequency curves  

USGS Publications Warehouse

This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

Riggs, H. C.

1968-01-01

83

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

84

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

85

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

86

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

87

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

88

Advances in modelling hysteretic water retention curve in deformable soils  

Microsoft Academic Search

Experimental findings on the hysteretic nature of the soil water retention curve, relating the degree of saturation to the matric suction, have generally to be superimposed with the aspects due to the deformability of the soil matrix. Indeed, most state-of-the-art models for retention curves only feature one of these two essential features, that is either capillary hysteresis or void ratio

Mathieu Nuth; Lyesse Laloui

2008-01-01

89

Comparison of calculated and measured hysteresis loss in multifilamentary superconducting wire  

Microsoft Academic Search

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

M. Ashkin; G. R. Wagner

1986-01-01

90

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

Microsoft Academic Search

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

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

2006-01-01

91

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

Microsoft Academic Search

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

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

1995-01-01

92

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

National Technical Information Service (NTIS)

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

D. Hayes B. Duncan

1974-01-01

93

Curved Mirrors  

NSDL National Science Digital Library

This inquiry activity will be used before discussing curved mirrors in class. Students will discover how curved mirrors act and how the size and the orientation of the image are related to the distance from the mirror. Ray diagrams for curved mirrors are

Horton, Michael

2009-05-30

94

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

95

Novel behavior in the M-H and field cooled (FC) curves of the MnFe2O4 nanoparticles synthesized by the coprecipitation method  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanoparticles were prepared by a coprecipitation chemical method. The average size of the obtained nanoparticles was about 30 nm. The hysteresis measured at T=300 K clearly shows ferromagnetic order at room temperature while that measured at T=450 K shows superparamagnetic behavior. The difference in the magnetization curves in the field increasing cycle and field decreasing cycle at higher temperatures (450 K or higher) is very unusual. In this case, a hysteresis in magnetization in higher magnetic fields with an opening up of the magnetization curve was observed. In this work, the effect of temperature and time of application of the applied field on the magnetization behavior was studied.

Vaez-zadeh, Mehdi; Mohammadi, Ali

2013-07-01

96

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

97

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

98

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

99

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

100

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

101

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

SciTech Connect

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

Niemi, A.; Bodvarsson, G.S.

1991-11-01

102

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

103

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

104

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

105

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

106

Macroscopic quantum tunneling of magnetization explored by quantum-first-order reversal curves  

NASA Astrophysics Data System (ADS)

A method to study the fundamental problem of quantum double well potential systems that display magnetic hysteresis is proposed. The method, coined quantum-first-order reversal curve (QFORC), is inspired by the first-order reversal curve, based on the Preisach model for hysteresis. We successfully tested the QFORC method in the hysteresis of the Mn12Ac molecular magnet, which is governed by macroscopic quantum tunneling of magnetization. The QFORC reproduces well the experimental magnetization behavior. It is possible to separate the thermal activation and tunneling contributions from the magnetization variation, as well as associate the magnetization jumps with specific quantum transitions.

Béron, Fanny; Novak, Miguel A.; Vaz, Maria G. F.; Guedes, Guilherme P.; Knobel, Marcelo; Caldeira, Amir; Pirota, Kleber R.

2013-07-01

107

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

108

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

109

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

110

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

111

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

112

"The Show"  

ERIC Educational Resources Information Center

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

Gehring, John

2004-01-01

113

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

114

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

115

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

116

Football curves  

NASA Astrophysics Data System (ADS)

Straight lines, zigzag, parabolas (possibly truncated), circles and spirals are the main curves which can be observed in football (in the European sense, soccer elsewhere). They are, respectively, associated to heavy kick, knuckleball, lob and banana kicks. We discuss their physical origin and determine their respective domain of existence.

Dupeux, Guillaume; Cohen, Caroline; Le Goff, Anne; Quéré, David; Clanet, Christophe

2011-07-01

117

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

118

Theoretical calculations of magnetic hysteresis and critical sizes for transitions between single-domain and multi-domain properties in titanomagnetites  

NASA Astrophysics Data System (ADS)

In this dissertation, I develop some theoretical tools to interpret measurements of magnetization in rocks, sediments and soils. I show that the magnetization curve for an ensemble of superparamagnetic particles depends only on odd moments of the volume distribution (< V>,< Vsp3>,\\...). As long as the ensemble is isotropic, the magnetic anisotropies of individual particles do not affect the curve. I derive analytical expressions for acquisition and loss of isothermal remanent magnetization in single-domain (SD) particles with uniaxial anisotropy. These curves depend only on the volume-average anisotropy. Plots of acquisition against loss of remanence can be used to distinguish uniaxial anisotropy from cubic anisotropy. I show that existing multi-domain (MD) hysteresis models, including the theory of Neel (1955) for thermoremanent magnetization, are internally inconsistent. I develop a simple self-consistent two-domain model and show that the slope of the hysteresis curve is always 1/N, where N is the demagnetizing factor for a two-domain particle. Using micromagnetic theory, I derive analytical expressions for the critical sizes Lsb{sw}, the upper limit for SD hysteresis, and Lsb{n}, the upper limit for stability of the SD remanent state. Lsb{sw} depends weakly on elongation and not at all on magnetocrystalline anisotropy, but$Lsbn = Lsbsw\\ ?ft({Nsbb/ Nsba}right)sp{sp{1/2}}?ft(1-{2kappa/musb0M{sbsps{2}}Nsba}right)sp{sp{-1/2}}where Nsba > Nsbb are demagnetizing factors and kappa depends on the combined magnetocrystalline and magnetoelastic anisotropy. Mainly because of the the difference in Ms,\\ Lsb{n} is orders of magnitude larger for a particle of Fesb{2.4}Tisb{0.6}Osb4 than for a particle of magnetite with the same aspect ratio. I develop a technique for eliminating unstable solutions of three-dimensional numerical micromagnetic models. I show that nucleation theory can be extended to non-ellipsoidal particles. The nucleation field Hsbn for a cuboid can be precisely located by a change in slope dM/dH and the appearance of curl in the magnetization. For a cube with Ksb1 = 0, the plot of Hsbn against 1/Lsp2 has the same slope as for a sphere, but the intercept is lower, reflecting a smaller average demagnetizing field. Hsbn$ is not affected by the demagnetizing field in the corners of the particle.

Newell, Andrew James

119

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

120

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

121

Novel hysteresis effect in ultrathin epitaxial Gd2O3 high-k dielectric  

Microsoft Academic Search

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

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

122

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

123

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

124

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

125

Influences affecting the soil-water characteristic curve  

Microsoft Academic Search

The soil-water characteristic curve (SWCC) is the primary partially saturated soil information as its behavior and properties can be derived from it. Although there have been many studies of unsaturated soils and the SWCC, there is still no combined constitutive model that can simulate soil characteristics accurately. In cases when hydraulic hysteresis is dominant (e.g. under cyclic loading) it is

ZHOU Jian; YU Jian-lin

2005-01-01

126

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

127

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

128

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

NASA Astrophysics Data System (ADS)

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

Schmidbauer, E.

1988-05-01

129

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

130

Trapping and hysteresis in two-phase flow in porous media 2: Impact of pore-network model results on continuum scale models  

NASA Astrophysics Data System (ADS)

The parameters and parameter functions of classical formulations of two-phase flow in porous media - the relative permeability - saturation relationship, the capillary pressure - saturation relationship, and the associated residual saturations - show path dependence, i.e. their values depend not only on the state variables but also on their drainage and imbibition history. Many models incorporate these hysteretic effects through ad-hoc adaptations based on fitting curves to experimental data. In addition, various physically based models identify different pore-scale phenomena as crucial. They range from Preisach-type models for dependent or independent domains, to identifying new state variables - e.g. interfacial area or non-percolating fluid saturations - to resolve hysteresis. Several models identify trapping and connectivity of fluids as an important contribution to macro-scale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are based on experiments or pore-network model results for the endpoints. However, experimental data or pore-scale model results are not available for the trajectories, i.e. the fate of the connectivity of the fluids while saturation changes. Hence, a validation of the different models is yet to be accomplished. Here, the impact of new results from a quasi-static pore-network model study on the change of the topology of the fluids during drainage and imbibition (see abstract: Trapping and hysteresis in two-phase flow in porous media 1: Pore-network modeling) on continuum scale models is discussed. The pore-network model results are compared to continuum-scale relationships from the literature and the consequences for the hysteresis models in which they are incorporated are evaluated. We find that while the models predict the qualitative trends they do not capture several interesting phenomena like a bifurcation depending on the connectivity of the remaining non-wetting phase at the endpoints of imbibition When one drainage follows one imbibition, the difference in fluid distributions due to this bifurcation is moderate. However, if the process type changes frequently, like in alternating injection scenarios for CO2 sequestration, models that do not include this phenomenon may lead to wrong estimates of trapped CO2.

Doster, F.; Joekar-Niasar, V.; Nordbotten, J. M.; Celia, M. A.

2011-12-01

131

A comparison of the diagnostic performance of the ST/HR hysteresis with cardiopulmonary stress testing parameters in detecting exercise-induced myocardial ischemia.  

PubMed

BACKGROUND: Because ST segment depression has limited diagnostic performance at exercise electrocardiography (ECG), ST segment depression/heart rate (ST/HR) hysteresis and cardiopulmonary exercise test (CPET)-derived parameters have been proposed as alternatives to diagnose exercise-induced myocardial ischemia. We compared the diagnostic performance of such parameters. METHODS: We studied 56 subjects (45 men, 11 women, age 59.7±13.6years) referred for suspected exercise-induced myocardial ischemia with an equivocal ECG exercise test. All subjects serially underwent CPET and a myocardial single-photon emission computerized tomography (SPECT) perfusion imaging (as the gold standard for ischemia). Maximum ST depression at peak exercise (ST-max), the ST/HR hysteresis, ?VO(2)/?WR b-b(1) slope, ?VO(2)/?WR (aa(1)-bb(1)), VO(2)/HR flattening duration and other CPET parameters were derived in all subjects. RESULTS: On the basis of SPECT, 23 subjects (41%) were considered ischemic and 33 subjects (59%) non-ischemic. ST/HR hysteresis was higher (0.026mV; 95% CI: 0.003 to 0.049 vs -0.016mV; 95% CI: -0.031 to -0.001mV) and ST-max was lower (-0.105mV; 95% CI: -0.158 to -0.052 vs 0.032mV; 95% CI: -0.001 to -0.066mV) in ischemic vs non-ischemic subjects (P=0.004 and P=0.001, respectively). Among CPET parameters, ?VO(2)/?WR b-b(1) slope was lower (9.4±3.8) and ?VO(2)/?WR (aa(1)-bb(1)) was higher (2.1±2.6) in ischemic vs non-ischemic subjects (11.4±2.3, P=0.005, and 1.1±1.5, P=0.001, respectively). The ST/HR hysteresis had the highest area under the curve value, better (P<0.05) than any other parameters tested, thus showing the highest overall diagnostic performance. CONCLUSION: The ST/HR hysteresis is superior to CPET-derived parameters for detecting exercise-induced myocardial ischemia in patients with equivocal ECG exercise test results. PMID:23260751

Zimarino, Marco; Barnabei, Luca; Madonna, Rosalinda; Palmieri, Giuseppe; Radico, Francesco; Tatasciore, Alfonso; Bellisarii, Francesco Iachini; Perrucci, Gianni Mauro; Corazzini, Alessandro; De Caterina, Raffaele

2012-12-20

132

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

133

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

134

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

135

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

136

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

137

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

138

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

139

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

140

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

141

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

142

Algebraic Curves in Structure From Motion  

Microsoft Academic Search

We introduce multiple-view geometry for algebraic curves, with appli- cations in both static and dynamic scenes. More precisely, we show when and how the epipolar geometry can be recovered from algebraic curves. For that purpose, we introduce a generalization of Kruppa's equations, which express the epipolar constraint for algebraic curves. For planar curves, we show that the homography through the

Jeremy Yirmeyahu Kaminski; Mina Teicher

143

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

NASA Astrophysics Data System (ADS)

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

Yamamoto, Daisuke; Danshita, Ippei

2013-07-01

144

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

145

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

NASA Astrophysics Data System (ADS)

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

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

1987-11-01

146

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

PubMed

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

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

2011-02-15

147

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

148

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

149

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

150

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

151

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

152

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

153

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

154

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

155

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

156

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

157

The Carnegie Curve  

NASA Astrophysics Data System (ADS)

The Earth's fair weather atmospheric electric field shows, in clean air, an average daily variation which follows universal time, globally independent of the measurement position. This single diurnal cycle variation (maximum around 19UT and minimum around 03UT) is widely known as the Carnegie curve, after the geophysical survey vessel of the Carnegie Institution of Washington on which the original measurement campaigns demonstrating the universal time variation were undertaken. The Carnegie curve's enduring importance is in providing a reference variation against which atmospheric electricity measurements are still compared; it is believed to originate from regular daily variations in atmospheric electrification associated with the different global disturbed weather regions. Details of the instrumentation, measurement principles and data obtained on the Carnegie's seventh and final cruise are reviewed here, also deriving new harmonic coefficients allowing calculation of the Carnegie curve for different seasons. The additional harmonic analysis now identifies changes in the phasing of the maximum and minimum in the Carnegie curve, which shows a systematic seasonal variation, linked to the solstices and equinoxes, respectively.

Harrison, R. Giles

2013-03-01

158

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

159

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

160

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

161

Magnetocrystalline anisotropy constants, rotational hysteresis energy and magnetic domain structure in UFe 6Al 6, UFe 9AlSi 2 and ScFe 10Si 2 intermetallic compounds  

Microsoft Academic Search

The magnetic torque, T, was applied to determine the anisotropy constants K1 and K2 of the UFe6Al6, UFe9AlSi2 and ScFe10Si2 compounds. The mechanism of magnetization reversal processes in these compounds was investigated on the basis of the analysis of the rotational hysteresis energy, Wr and rotational hysteresis integral, R, calculated from the magnetic torque curves. Applying the powder pattern method,

J. J. Wyslocki; W. Suski; P. Pawlik; K. Wochowski; B. Kotur; O. I. Bodak

1996-01-01

162

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

163

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

164

HUMAN GROWTH CURVE.  

PubMed

The human growth curve shows two (and only two) outstanding periods of accelerated growth-the circumnatal and the adolescent. The circumnatal growth cycle attains great velocity, which reaches a maximum at the time of birth. The curve of this cycle is best fitted by a theoretical skew curve of Pearson's Type I. It has a theoretical range of 44 months and a standard deviation of 5.17 months. The modal velocity is 10.2 kilos per year. The adolescent growth cycle has less maximum velocity and greater range in time than the circumnatal cycle. The best fitting theoretical curve is a normal frequency curve ranging over about 10 years with a standard deviation of about 21 months and a modal velocity of 4.5 kilos per year. The two great growth accelerations are superimposed on a residual curve of growth which measures a substratum of growth out of which the accelerations arise. This probably extends from conception to 55 years, on the average. It is characterized by low velocity, averaging about 2 kilos per year from 2 to 12 years. It is interpreted as due to many growth operations coincident or closely blending in time. Our curve shows no third marked period of acceleration at between the 3rd and 6th years. The total growth in weight of the body is the sum of the weight of its constituent organs. In some cases these keep pace with the growth of the body as a whole; great accelerations of body growth are due to great accelerations in growth of the constituent organs. In other cases one of the organs of the body (like the thymus gland) may undergo a change in weight that is not in harmony with that of the body as a whole. The development of the weight in man is the resultant of many more or less elementary growth processes. These result in two special episodes of growth and numerous smaller, blending, growth operations. Hypotheses are suggested as to the basis of the special growth accelerations. PMID:19872316

Davenport, C B

1926-11-20

165

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

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

166

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.

167

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

168

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

169

Standard Mastery Curves and Skew Curves.  

ERIC Educational Resources Information Center

The objective of the study is to convince educational researchers of the necessity for "standard mastery curves" for the graphical representation of scores on summative tests for a group of students. Attention is drawn to the study of theoretical and empirical skew curves in education and biology. Use of standard mastery curves and study of skew…

Warries, Egbert

170

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

171

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

172

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

173

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

174

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

175

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

PubMed

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

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

2012-08-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

177

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

178

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

179

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

180

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

181

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

182

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

183

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

184

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

185

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

186

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

187

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

188

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

189

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

190

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

191

[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

192

Suspended-sediment rating curve response to urbanization and wildfire, Santa Ana River, California  

USGS Publications Warehouse

River suspended-sediment concentrations provide insights to the erosion and transport of materials from a landscape, and changes in concentrations with time may result from landscape processes or human disturbance. Here we show that suspended-sediment concentrations in the Santa Ana River, California, decreased 20-fold with respect to discharge during a 34-year period (1968-2001). These decreases cannot be attributed to changes in sampling technique or timing, nor to event or seasonal hysteresis. Annual peak and total discharge, however, reveal sixfold increases over the 34-year record, which largely explain the decreases in sediment concentration by a nonlinear dilution process. The hydrological changes were related to the widespread urbanization of the watershed, which resulted in increases in storm water discharge without detectable alteration of sediment discharge, thus reducing suspended-sediment concentrations. Periodic upland wildfire significantly increased water discharge, sediment discharge, and suspended-sediment concentrations and thus further altered the rating curve with time. Our results suggest that previous inventories of southern California sediment flux, which assume time-constant rating curves and extend these curves beyond the sampling history, may have substantially overestimated loads during the most recent decades.

Warrick, J. A.; Rubin, D. M.

2007-01-01

193

Cyclic stress-strain curves at finite strains under high pressures in crystalline polymers  

Microsoft Academic Search

The cyclic torsional stress-strain behaviour for crystalline polymers of polyethylene (PE), polypropylene (PP) and polyoxymethylene (POM) was investigated at finite strain amplitude under hydrostatic pressure up to 2000 kgf cm-2. The following features for the cyclic stress-strain curves were indicated. (1) Two types of cyclic stress-strain curve were observed: one was a PE type where the present hysteresis loop was

M. Kitagawa; J. Qui; K. Nishida; T. Yoneyama

1992-01-01

194

Points on Computable Curves of Computable Lengths  

NASA Astrophysics Data System (ADS)

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

Rettinger, Robert; Zheng, Xizhong

195

Rational curves and rational singularities  

Microsoft Academic Search

We study rational curves on algebraic varieties, especially on normal affine varieties endowed with a $\\\\C^*$-action. For varieties with an isolated singularity, we show that the presence of sufficiently many rational curves outside the singular point strongly affects the character of the singularity. This provides an explanation of classical results due to H.A. Schwartz and G.H. Halphen on polynomial solutions

Hubert Flenner; Mikhail Zaidenberg

2001-01-01

196

Rational curves and rational singularities  

Microsoft Academic Search

.  ?We study rational curves on algebraic varieties, especially on normal affine varieties endowed with a ?*-action. For varieties with an isolated singularity, covered by a family of rational curves with a general member not passing\\u000a through the singular point, we show that this singularity is rational. In particular, this provides an explanation of classical\\u000a results due to H. A. Schwartz

Hubert Flenner; Mikhail Zaidenberg

2003-01-01

197

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

198

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

199

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

Microsoft Academic Search

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

N. Ortiz de Adler; J. R. Manzano

1995-01-01

200

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

PubMed

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

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

2011-05-26

201

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

NASA Astrophysics Data System (ADS)

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

Ogorelec, Z.

1999-05-01

202

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

203

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

204

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

205

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

206

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

207

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

208

Efficient elliptic curve exponentiation  

Microsoft Academic Search

Elliptic curve cryptosystems, proposed by Koblitz([8]) andMiller([11]), can be constructed over a smaller definition field than theElGamal cryptosystems([5]) or the RSA cryptosystems([16]). This is whyelliptic curve cryptosystems have be un to attract notice. There aremainly two types in elliptic curve cryptosystems, elliptic curves E overIF 2 r and E over IFp . Some current systems based on ElGamal or RSAmay

Atsuko Miyaji; Takatoshi Ono; Henri Cohen

1997-01-01

209

Standard Decrement Curves  

Microsoft Academic Search

For circuit breaker and relay application, it is frequently necessary to determine the decrement in power system short-circuit currents. For this purpose certain ``standard decrement curves'' approved by the National Electrical Manufacturers Association have been in general use. The original curves appeared in 1918 and a revised set was prepared in 1923. New decrement curves given in the present paper

W. C. Hahn; C. F. Wagner

1932-01-01

210

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

211

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

212

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

213

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

214

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

215

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

NASA Astrophysics Data System (ADS)

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

Ekkachai, Kittipong; Tungpimolrut, Kanokvate; Nilkhamhang, Itthisek

2013-11-01

216

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

217

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

218

Disk galaxy rotation curves  

NASA Astrophysics Data System (ADS)

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

Banhatti, Dilip G.; Datta, Rahul

219

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

PubMed

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

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

2009-02-15

220

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

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

221

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

222

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

223

Dynamics of the background outward current of single guinea pig ventricular myocytes. Ionic mechanisms of hysteresis in cardiac cells.  

PubMed

Subthreshold potentials are thought to be mediated by time-independent, "passive" background currents. In this study, we show that the background current-voltage (I-V) relation of guinea pig ventricular myocytes is changed significantly by repetitive stimulation, in such a way that cell excitability becomes enhanced. Myocytes were used for whole-cell voltage-clamp experiments. A voltage-clamp ramp (100 mV/sec) to -50 mV was applied from a holding potential of -100 mV. Subsequently, a train of square voltage-clamp pulses to +10 mV (duration, 300 msec; interpulse interval, 300 msec) was delivered from a holding potential of -85 mV. A new ramp was applied again immediately after the train, and the resulting I-V curve was compared with that obtained before the train. Pulsing displaced the I-V relation to the right, the zero-current point becoming 1-2 mV less negative, and increased the degree of inward-going rectification. These changes were insensitive to tetrodotoxin (30 microM); disappeared during superfusion with cobalt (2 mM), verapamil (22 microM), or ryanodine (5 microM); and could not be mimicked by agonists of the protein kinase C system. In the presence of cesium (8 mM), pulsing still displaced the I-V curve to the right. However, the linear portion of the curve became steeper after the train. Subtraction of the cesium-sensitive current from control revealed that, although the zero-current point remained constant, the I-V relation showed a stronger inward-going rectification after pulsing. In accordance with these results, we have demonstrated hysteresis of excitability in ventricular myocytes. We conclude that the observed changes are mediated by an increase in intracellular calcium, which leads to an increase in rectification of IK1, as well as to activation of another membrane-conductance system, perhaps the Na-Ca exchange or the Ca(2+)-activated, nonselective current. PMID:1934360

Delmar, M; Ibarra, J; Davidenko, J; Lorente, P; Jalife, J

1991-11-01

224

Assessment of curve progression in idiopathic scoliosis.  

PubMed

In a 5-year prospective study on idiopathic scoliosis, an attempt was made to elucidate the natural history of the disease and to determine which factors contribute to curve progression. A total of 85,622 children were examined for scoliosis in a prospective school screening study carried out in northwestern and central Greece. Curve progression was studied in 839 of the 1,436 children with idiopathic scoliosis of at least 10 degrees detected from the school screening program. Each child was followed clinically and roentgenographically for one to four follow-up visits for a mean of 3.2 years. Progression of the scoliotic curve was recorded in 14.7% of the children. Spontaneous improvement of at least 5 degrees was observed in 27.4% of them, with 80 children (9.5%) demonstrating complete spontaneous resolution. Eighteen percent of the patients remained stable, while the remaining patients demonstrated nonsignificant changes of less than 5 degrees in curve magnitude. A strong association was observed between the incidence of progression and the sex of the child, curve pattern, maturity, and to a lesser extent age and curve magnitude. More specifically, the following were associated with a high risk of curve progression: sex (girls); curve pattern (right thoracic and double curves in girls, and right lumbar curves in boys); maturity (girls before the onset of menses); age (time of pubertal growth spurt); and curve magnitude (> or = 30 degrees). On the other hand, left thoracic curves showed a weak tendency for progression. In conclusion, the findings of the present study strongly suggest that only a small percentage of scoliotic curves will undergo progression. The pattern of the curve according to curve direction and sex of the child was found to be a key indicator of which curves will progress. PMID:9765033

Soucacos, P N; Zacharis, K; Gelalis, J; Soultanis, K; Kalos, N; Beris, A; Xenakis, T; Johnson, E O

1998-01-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

226

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

227

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

PubMed

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

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

2013-09-11

228

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

PubMed

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

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

2002-08-02

229

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

NASA Astrophysics Data System (ADS)

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

Werner, Adrian D.; Lockington, David A.

2006-06-01

230

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

231

Nonequilibrium hysteresis and Wien effect water dissociation at a bipolar membrane  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

232

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

NASA Astrophysics Data System (ADS)

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

Hergt, Rudolf; Dutz, Silvio; Röder, Michael

2008-09-01

233

Ranking intersecting Lorenz curves  

Microsoft Academic Search

This paper is concerned with the problem of ranking Lorenz curves in situations where the Lorenz curves intersect and no unambiguous\\u000a ranking can be attained without introducing weaker ranking criteria than first-degree Lorenz dominance. To deal with such\\u000a situations two alternative sequences of nested dominance criteria between Lorenz curves are introduced. At the limit the systems\\u000a of dominance criteria appear

Rolf Aaberge

2009-01-01

234

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

235

Flicker Curves of Different Types of Lamps  

Microsoft Academic Search

In the Netherlands, grid operators' database of complaints on voltage show that almost 60% of all complaints is about flicker problems. The evaluation and measurement of flicker becomes an important issue. The simplest method used in industry is flicker curves (Pst = 1), showed in IEEE standard and UIE publication (1) (2). These flicker curves are obtained by only considering

Rong Cai; J. F. G. Cobben; J. M. A. Myrzik; W. L. Kling

2006-01-01

236

Ultrasonic Fetal Cephalometry: Percentiles Curve  

Microsoft Academic Search

Measurements by ultrasound of the biparietal diameter of the fetal head during pregnancy are a reliable guide to fetal growth. As a ready means of comparison with the normal we constructed from 4,170 measurements in 1,394 cases a curve showing the percentiles distribution of biparietal diameters for each week of gestation.

P. Flamme

1972-01-01

237

Equivalent Curves in Surfaces  

Microsoft Academic Search

We consider various notions of equivalence for homotopy classes of curves on hyperbolic surfaces based on topological, algebraic, and geometric structures, and find the relationships between these equivalences.

Christopher J. Leininger

2003-01-01

238

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

239

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

NASA Astrophysics Data System (ADS)

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

Haraguchi, Tadao; Shimada, Ryohachi; Takeyama, Toshiro

240

Titania nanorods curve to lower their energy.  

PubMed

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

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

2013-08-01

241

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

242

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

243

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

244

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

245

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

246

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

247

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

248

Grading on the Curve.  

ERIC Educational Resources Information Center

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

Wall, Charles R.

1987-01-01

249

Classification Using Growth Curves  

Microsoft Academic Search

Classification using the growth curve model is analyzed according to whether the covariance matrix structure is known to be compound symmetric. A new classification procedure appropriate for classification in the case of models with means that follow a Potthoff and Roy [Potthoff, R. F., Roy, S. N. (1964). A generalized multivariate analysis of variance model useful especially for growth curve

Graciela B. Mentz; Anant M. Kshirsagar

2005-01-01

250

Analyzing population growth curves  

Microsoft Academic Search

Assessing animal population growth curves is an essential feature of field studies in ecology and wildlife management. We used five models to assess population growth rates with a number of sets of population growth rate data. A 'generalized' logistic curve provides a better model than do four other popular models. Use of difference equations for fitting was checked by a

L. L. Eberhardt; J. M. Breiwick; D. P. Demaster

2008-01-01

251

AND NEGATIVELY CURVED SPACES  

Microsoft Academic Search

The paper sketches a recent progress and formulates several open prob- lems in studying equivariant quasiconformal and quasisymmetric homeomorphisms in negatively curved spaces as well as geometry and topology of noncompact geo- metrically finite negatively curved manifolds and their boundaries at infinity having Carnot-Caratheodory structures. Especially, the most interesting are complex hy- perbolic manifolds with Cauchy-Riemannian structure at infinity, which

Boris Apanasov

252

Hyperelliptic Curves and Cryptography  

Microsoft Academic Search

In 1989, Koblitz proposed using the jacobian of a hyperel- liptic curve deflned over a flnite fleld to implement discrete logarithm cryptographic protocols. This paper provides an overview of algorithms for performing the group law (which are necessary for the e-cient imple- mentation of the protocols), and algorithms for solving the hyperelliptic curve discrete logarithm problem (whose intractability is essential

Michael Jacobson; Alfred Menezes; Andreas Stein

2004-01-01

253

Source Discrimination from Magnitude Curve  

NASA Astrophysics Data System (ADS)

Theoretical and numerical examinations on "magnitude curves" from explosions and earthquakes with various source time functions were made. The body-wave magnitude curve mb (T) is obtained by applying a series of narrow band-pass filters (0.75 f0 - 1.25 f0) at center frequencies f0 to instrument-corrected ground motions of P waves (0.1 <= f <= 10 Hz). The mb formula of Veith and Clawson (1972) is employed at these center periods. At each station, both raw and corrected magnitude curves have the same slopes and shapes with period since the correction factor depends not on frequency but on source depth and station distance. The surface-wave magnitude MS (T) curve is similarly obtained in the period range from 2 to 100 sec. The mb magnitude curves from an explosion source show sharp peaks with slopes +1 and -1 as well as +2 and -2 (1.5 and -1.5 for MS (T) magnitude curves) varied with log period at 0 or 5 km source depth. The mb magnitude curves from earthquakes are flat plateaus (slopes of 0; -0.5 for MS (T) curves) varied with log period at 0 or 5 km depth. For the case of an explosion plus tectonic release, a sharp magnitude peak for the explosion component and a flat plateau of slope 0 for the tectonic component for mb (T) (nearly flat plateau of slope -0.5 for MS (T)) are shown. The long-period magnitude falloff is controlled by the power dependence of T^(p+0-2) for body waves or T^(p+0.5-2) for surface waves: the T^p of the far-field (source) spectrum, the T^(-2) of amplitude to magnitude, T^0 of the far-field body-wave amplitude factor, and T^0.5 of the far-field surface-wave amplitude factor. The value of p is -2, -1, 0, +1, or +2. This approach is tested with ten events: five are known earthquakes and five are known explosions. With respect to body waves, the average body-wave magnitude curves for known explosion sources indicate triangular peaks of slopes +1 and -1 as well as +2 and -2 with log period. Known earthquake sources exhibit flat body-wave magnitude peaks with slopes 0 and the flanks with slopes +-1 and/or +-2. Known explosion events with tectonic release exhibit two body-wave magnitude peaks: one is an explosion triangular peak and the second peak which can be thought as slope combinations from explosion and earthquake.

Nguyen, B. V.

2011-12-01

254

Stellar Blackbody Radiation Curves  

NSDL National Science Digital Library

Stellar Blackbody Radiation Curves model simulates the blackbody radiation curve of stars and how this leads to the observed color and luminosity of the star. If a star can be treated as a blackbody, the blackbody radiation curve of the star, the power density per area (or intensity) per wavelength (energy/time/volume) vs wavelength, is dependent on the star's temperature (spectral class). In the simulation, the star is shown along with its luminosity and spectral class. In separate graph, the blackbody radiation curve, the visible part of the spectrum, and the integrated stellar surface intensity (integrating the blackbody curve over all wavelengths) are shown. In another window the HR diagram can be shown indicating the current star's parameters. The radius of the star (in Rsun) and the temperature of the star in Kelvin (5780 K is Tsun) can be changed.

Belloni, Mario

2010-11-11

255

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

256

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

257

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

258

Measuring Extinction Curves of Lensing Galaxies  

NASA Astrophysics Data System (ADS)

We critique the method of constructing extinction curves of lensing galaxies, using multiply imaged QSOs. If one of the two QSO images is lightly reddened, or if the dust along both sight lines has the same properties, then the method works well and produces an extinction curve for the lensing galaxy. These cases are likely rare and hard to confirm. However, if the dust along each sight line has different properties, then the resulting curve is no longer a measurement of extinction. Instead, it is a measurement of the difference between two extinction curves. This ``lens difference curve'' does contain information about the dust properties, but extracting a meaningful extinction curve is not possible without additional, currently unknown information. As a quantitative example, we show that the combination of two Cardelli, Clayton, and Mathis (CCM)-type extinction curves with different values of RV produces a CCM extinction curve with a value of RV that is dependent on the individual RV values and the ratio of V-band extinctions. The resulting lens difference curve is not an average of the dust along the two sight lines. We find that lens difference curves with any value of RV, even negative values, can be produced by a combination of two reddened sight lines with different CCM extinction curves with RV values consistent with Milky Way dust (2.1<=RV<=5.6). This may explain extreme values of RV inferred by this method in previous studies. However, lens difference curves with more normal values of RV are just as likely to be composed of two dust-extinction curves with RV values different from that of the lens difference curve. While it is not possible to determine the individual extinction curves making up a lens difference curve, there is information about a galaxy's dust contained in the lens difference curves. If the lens difference curve can be fit with the CCM relationship (regardless of the fitted RV value), this implies that the dust along the two sight lines can be described by CCM. In addition, the presence of the 2175 Å feature in the lens difference curve means that this feature is present along at least one of the two lensed sight lines.

McGough, Christina; Clayton, Geoffrey C.; Gordon, Karl D.; Wolff, Michael J.

2005-05-01

259

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

260

MCMC curve sampling for image segmentation.  

PubMed

We present an algorithm to generate samples from probability distributions on the space of curves. We view a traditional curve evolution energy functional as a negative log probability distribution and sample from it using a Markov chain Monte Carlo (MCMC) algorithm. We define a proposal distribution by generating smooth perturbations to the normal of the curve and show how to compute the transition probabilities to ensure that the samples come from the posterior distribution. We demonstrate some advantages of sampling methods such as robustness to local minima, better characterization of multi-modal distributions, access to some measures of estimation error, and ability to easily incorporate constraints on the curve. PMID:18044603

Fan, Ayres C; Fisher, John W; Wells, William M; Levitt, James J; Willsky, Alan S

2007-01-01

261

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

262

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

263

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

264

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

265

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

266

Unwrapping Closed Timelike Curves  

NASA Astrophysics Data System (ADS)

Closed timelike curves (CTCs) appear in many solutions of the Einstein equation, even with reasonable matter sources. These solutions appear to violate causality and so are considered problematic. Since CTCs reflect the global properties of a spacetime, one can attempt to extend a local CTC-free patch of such a spacetime in a way that does not give rise to CTCs. One such procedure is informally known as unwrapping. However, changes in global identifications tend to lead to local effects, and unwrapping is no exception, as it introduces a special kind of singularity, called quasi-regular. This “unwrapping” singularity is similar to the string singularities. We define an unwrapping of a (locally) axisymmetric spacetime as the universal cover of the spacetime after one or more of the local axes of symmetry is removed. We give two examples of unwrapping of essentially 2+1 dimensional spacetimes with CTCs, the Gott spacetime and the Gödel spacetime. We show that the unwrapped Gott spacetime, while singular, is at least devoid of CTCs. In contrast, the unwrapped Gödel spacetime still contains CTCs through every point. A “multiple unwrapping” procedure is devised to remove the remaining circular CTCs. We conclude that, based on the given examples, CTCs appearing in the solutions of the Einstein equation are not simply a mathematical artifact of coordinate identifications. Alternative extensions of spacetimes with CTCs tend to lead to other pathologies, such as naked quasi-regular singularities.

Slobodov, Sergei

2008-12-01

267

Measuring Model Rocket Engine Thrust Curves  

ERIC Educational Resources Information Center

|This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…

Penn, Kim; Slaton, William V.

2010-01-01

268

DIURNAL BODY TEMPERATURE CURVES IN SHIFT WORKERS  

Microsoft Academic Search

Observations on body temperature at rest of three workers inexperienced in shift work presented, when working in dayshift, the normal well-known diurnal curve, and when working in nightshift a pattern significantly different from the normal one. The throe subjects showed a striking congruence of curves. During a nightshift, period of several weeks in succession every week appeared to involve a

J. H. van LOON

1963-01-01

269

New Keynesian Economics and the Phillips Curve  

Microsoft Academic Search

Models with sticky prices are an important part of New Keynesian economics. The author shows that several of the New Keynesian models imply a formulation that is similar to the expectations-augmented Phillips curve of Milton Friedman and Edmund Phelps. He then presents new estimates of the New Keynesian Phillips curve. The author uses two proxies for price expectations: survey-based measures

John M. Roberts

1995-01-01

270

Estimation and comparison of flowering curves  

Microsoft Academic Search

Background: Many researchers have simply recorded first flowering dates, while others have recorded the full extent of flowering. Such flowering curves show the rate of increase and decrease in flowering, as well as the day on which flowering is a maximum.Aim: To develop objective statistical methods for the estimation and comparison of flowering curves, with particular emphasis on the date

Robert M. Clark; Roy Thompson

2011-01-01

271

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

272

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

273

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

274

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

275

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

276

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

277

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

278

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

279

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

280

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

281

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

282

Curved Girder Computer Manual.  

National Technical Information Service (NTIS)

This report presents three computer programs based on analytical techniques of the slope deflection Fourier Series previously developed under this HP and R study. The COBRA (Curved Orthotropic Bridge Analysis) slope deflection computer programs can be use...

L. C. Bell C. P. Heins

1969-01-01

283

Bragg Curve Spectroscopy  

SciTech Connect

An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously.

Gruhn, C.R.

1981-05-01

284

Logistic Curve Demo  

NSDL National Science Digital Library

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

Roberts, Lila F.; Hill, David R.

2002-02-03

285

The Bell Curve  

NSDL National Science Digital Library

This lesson is designed to introduce students to the normal distribution or bell curve. The lesson also discusses controversy behind the interpretation of the bell curve. This lesson provides links to discussions and activities related to the normal distribution as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2010-01-01

286

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

PubMed Central

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

Othman, Sarbaz; Thomson, Robert; Lanner, Gunnar

2010-01-01

287

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

PubMed

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

Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

2010-01-01

288

Breakpoint chlorination curves of greywater.  

PubMed

A study on chlorination of raw greywater with hypochlorite is reported in this paper. Samples were chlorinated in a variety of conditions, and residual chlorine (Cl2) was measured spectrophotometrically. For each sample, the chlorination curve (chlorine residuals versus chlorine dose) was obtained. Curves showed the typical hump-and-dip profile attributable to the formation and destruction of chloramines. It was observed that, after reactions with strong reductants and chloramines-forming compounds, the remaining organic matter exerted a certain demand of chlorine. The evolution of chlorination curves with addition of ammonia and dodecylbencene sulfonate sodium salt and with dilution of the greywater sample were studied. In addition, chlorination curves at several contact times have been obtained, resulting in slower chlorine decay in the hump zone than in the dip zone. In addition, the decay of coliforms in chlorinated samples was also investigated. It was found that, for a chlorination dosage corresponding to the maximum of the hump zone (average 8.9 mg Cl2/ L), samples were negative in coliforms after 10 to 30 minutes of contact time. After-growth was not observed within 3 days after chlorination. Implications in chlorination treatments of raw greywater can be derived from these results. PMID:17824528

March, J G; Gual, M

2007-08-01

289

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

290

Correlation between the hysteresis and the initial defect density of graphene  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

291

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

292

Curve following in illiquid markets  

Microsoft Academic Search

In this article the problem of curve following in an illiquid market is addressed. The optimal control is characterised in\\u000a terms of the solution to a coupled FBSDE involving jumps via the technique of the stochastic maximum principle. Analysing\\u000a this FBSDE, we further show that there are buy and sell regions. In the case of quadratic penalty functions the FBSDE

Felix Naujokat; Nicholas Westray

2011-01-01

293

Television Quiz Show Simulation  

ERIC Educational Resources Information Center

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

Hill, Jonnie Lynn

2007-01-01

294

Disease risk curves.  

PubMed

ABSTRACT Disease risk curves are simple graphical relationships between the probability of need for treatment and evidence related to risk factors. In the context of the present article, our focus is on factors related to the occurrence of disease in crops. Risk is the probability of adverse consequences; specifically in the present context it denotes the chance that disease will reach a threshold level at which crop protection measures can be justified. This article describes disease risk curves that arise when risk is modeled as a function of more than one risk factor, and when risk is modeled as a function of a single factor (specifically the level of disease at an early disease assessment). In both cases, disease risk curves serve as calibration curves that allow the accumulated evidence related to risk to be expressed on a probability scale. When risk is modeled as a function of the level of disease at an early disease assessment, the resulting disease risk curve provides a crop loss assessment model in which the downside is denominated in terms of risk rather than in terms of yield loss. PMID:23531177

Hughes, G; Burnett, F J; Havis, N D

2013-11-01

295

Comment to ATEL #4395: MAXI/GSC X-ray light curve of 4U 1630-472 updated with the latest calibration shows no drop in soft X-ray (2-4 keV) band on 2012 September 18  

NASA Astrophysics Data System (ADS)

We reprocessed the MAXI/GSC data using the latest calibration data, then found that the sharp soft-X-ray drop in 2-4 keV band as seen in the past archived files at http://maxi.riken.jp/top/index.php?cid=1&jname=J1634-473 and reported in ATEL #4395 was due to the calibration issue in the quick-look analysis process. The drop of the 2-4 keV band cannot be seen in the light curve processed using the latest calibration files.

Sugizaki, M.; Ueno, S.; Tomida, H.; Nakahira, S.; Ishikawa, M.; Mihara, T.; Serino, M.; Yamamoto, T.; Sugimoto, J.; Matsuoka, M.; Kawai, N.; Morii, M.; Usui, R.; Ishikawa, K.; Yoshida, A.; Tsunemi, H.; Kimura, M.; Negoro, H.; Nakajima, M.; Asada, M.; Sakakibara, H.; Serita, N.; Ueda, Y.; Hiroi, K.; Shidatsu, M.; Sato, R.; Tsuboi, Y.; Yamauchi, M. Higa M.; Nishimura, Y.; Hanayama, T.; Yoshidome, K.; Yamaoka, K.

2012-09-01

296

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

297

Dynamics of curved interfaces  

SciTech Connect

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

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

2009-08-15

298

7 CFR 43.105 - Operating characteristics (OC) curves.  

Code of Federal Regulations, 2013 CFR

...Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS STANDARDS FOR SAMPLING PLANS Sampling Plans § 43.105 Operating characteristics (OC) curves. The OC curves shows the ability of...

2013-01-01

299

A Holographic Road Show.  

ERIC Educational Resources Information Center

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

Kirkpatrick, Larry D.; Rugheimer, Mac

1979-01-01

300

The Diane Rehm Show  

NSDL National Science Digital Library

The Diane Rehm Show has its origins in a mid-day program at WAMU in Washington, D.C. Diane Rehm came on to host the program in 1979, and in 1984 it was renamed "The Diane Rehm Show". Over the past several decades, Rehm has played host to hundreds of guests, include Archbishop Desmond Tutu, Julie Andrews, and President Bill Clinton. This website contains an archive of her past programs, and visitors can use the interactive calendar to look through past shows. Those visitors looking for specific topics can use the "Topics" list on the left-hand side of the page, or also take advantage of the search engine. The show has a number of social networking links, including a Facebook page and a Twitter feed.

301

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

302

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

303

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

304

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

305

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

306

Uncertainty propagation: Curve fitting  

NSDL National Science Digital Library

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

Liao, David

307

Curved Solids Nets  

ERIC Educational Resources Information Center

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

Cohen, Nitsa

2003-01-01

308

RATIONAL NORMAL CURVE  

Microsoft Academic Search

The paper has two goals: the study of the associated graded ring of contracted homogeneous ideals in K(x, y) and the study of the Grobner fan of the ideal P of the rational normal curve in Pd. These two problems are, quite surprisingly, very tightly related. We completely classify the contracted ideals with a Cohen-Macaulay associated graded rings in terms

ALDO CONCA; EMANUELA DE NEGRI; MARIA EVELINA ROSSI

309

Electrostatic curved electrode actuators  

Microsoft Academic Search

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

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

1997-01-01

310

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

311

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

312

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

313

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

314

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

315

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

316

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

317

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

318

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

319

Do Elephants Show Empathy?  

Microsoft Academic Search

Elephants show a rich social organization and display a number of unusual traits. In this paper, we analyse reports collected over a thirty-five year period, describing behaviour that has the potential to reveal signs of empathic understanding. These include coalition formation, the offering of protection and comfort to others, retrieving and 'babysitting' calves, aiding individuals that would otherwise have difficulty

Lucy A. Bates; Phyllis C. Lee; Norah Njiraini; Joyce H. Poole; Katito Sayialel; Soila Sayialel; Cynthia J. Moss; Richard W. Byrne

2008-01-01

320

What Do Maps Show?  

ERIC Educational Resources Information Center

|This curriculum packet, appropriate for grades 4-8, features a teaching poster which shows different types of maps (different views of Salt Lake City, Utah), as well as three reproducible maps and reproducible activity sheets which complement the maps. The poster provides teacher background, including step-by-step lesson plans for four geography…

Geological Survey (Dept. of Interior), Reston, VA.

321

Shakespearean Slide Shows.  

ERIC Educational Resources Information Center

|Presents a condensed method for involving students in the kind of theatrical problem-solving that transforms a script to a play. Describes how to incorporate a "human slide show" into the class. Notes that students must read plays not just to understand events, but to make artistic choices about how to stage the action so that an audience…

Flynn, Rosalind M.

2002-01-01

322

Btu accounting: Showing results  

Microsoft Academic Search

In the preceding article in this series last month, the author showed how to calculate the energy consumed to make a pound of product. To realize a payoff, however, the results must be presented in graphs or tables that clearly display what has happened. They must call attention to plant performance and ultimately lead to more efficient use of energy.

1994-01-01

323

Stage a Water Show  

ERIC Educational Resources Information Center

In the author's book titled "The Incredible Water Show," the characters from "Miss Alaineus: A Vocabulary Disaster" used an ocean of information to stage an inventive performance about the water cycle. In this article, the author relates how she turned the story into hands-on science teaching for real-life fifth-grade students. The author also…

Frasier, Debra

2008-01-01

324

ISU Demonstration Road Show  

NSDL National Science Digital Library

The Idaho State University Department of Physics conducts science demonstration shows at SE Idaho schools. Four different presentations are currently available; "Forces and Motion", "States of Matter", "Electricity and Magnetism", and "Sound and Waves". Student activities and descriptions of the demonstrated material are also provided.

Shropshire, Steven

2004-04-06

325

Growth curves for Laron syndrome.  

PubMed Central

Growth curves for children with Laron syndrome were constructed on the basis of repeated measurements made throughout infancy, childhood, and puberty in 24 (10 boys, 14 girls) of the 41 patients with this syndrome investigated in our clinic. Growth retardation was already noted at birth, the birth length ranging from 42 to 46 cm in the 12/20 available measurements. The postnatal growth curves deviated sharply from the normal from infancy on. Both sexes showed no clear pubertal spurt. Girls completed their growth between the age of 16-19 years to a final mean (SD) height of 119 (8.5) cm whereas the boys continued growing beyond the age of 20 years, achieving a final height of 124 (8.5) cm. At all ages the upper to lower body segment ratio was more than 2 SD above the normal mean. These growth curves constitute a model not only for primary, hereditary insulin-like growth factor-I (IGF-I) deficiency (Laron syndrome) but also for untreated secondary IGF-I deficiencies such as growth hormone gene deletion and idiopathic congenital isolated growth hormone deficiency. They should also be useful in the follow up of children with Laron syndrome treated with biosynthetic recombinant IGF-I.

Laron, Z; Lilos, P; Klinger, B

1993-01-01

326

Climate Hysteresis for Planets Orbiting Stars of Different Spectral Type  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

327

Does noise reduction matter for curve fitting in growth curve models?  

PubMed

In this paper, we discuss the efficiency of noise reduction for curve fitting in nonlinear growth curve models. We use singular spectrum analysis as a nonlinear-nonparametric denoising method. A set of longitudinal measurements is used in considering the performance of the method. We also use artificially generated data sets with and without noise for the purpose of validation of the results obtained in this study. The results show that noise reduction is important for curve fitting in growth curve models and also, that the singular spectrum analysis technique can be used as a powerful tool for noise reduction in longitudinal measurements. PMID:19573946

Hassani, Hossein; Zokaei, Mohammad; von Rosen, Dietrich; Amiri, Saeid; Ghodsi, Mansoureh

2009-07-01

328

Viewing television talk shows  

Microsoft Academic Search

We examined how motivation, audience activity, and attitudes influenced the likelihood of watching societal?issue and relational topics on television talk programs. Path analysis supported differences in ritualized and instrumental motives for watching talk shows. Information and exciting?entertainment motivation predicted greater’ realism of, affinity with, involvement with, and intent to watch talk television. Pass?time motivation predicted reduced affinity with and intent

Alan M. Rubin; Mary M. Step

1997-01-01

329

The Truman Show  

Microsoft Academic Search

The Truman Show is hardly a film you would automatically speak about as a game. At first glance, it is tempting to interpret the story of\\u000a Truman Burbank — his perpetual subjection to the artificial (televisual) world of Seahaven and its gargantuan reality TV project,\\u000a his eventual escape from the “OmniCam Ecosphere” building and the paternalistic surveillance of director Christof

Rolf F. Nohr

330

Computation of superconductor critical current densities and magnetization curves  

SciTech Connect

Using a constitutive law for superconductor hysteresis and the ideas of the critical state model, a system of equations is developed for the critical current density J{sub c}, the equilibrium magnetization M{sub e}, the upper and lower portions, M{sub U} and M{sub L}, of the major hysteresis loop, and their derivatives with respect to the applied field. The constitutive law consists of a differential equation relating the time rate of change of the flux density B to that of the applied field, {dot B} = {alpha}(H){vert bar}{dot H}{vert bar}(f(H) {minus} B) + {dot H}g(H), and a rule governing the abrupt changes observed at the turning points of H. For the case presented here in which f, g, and {alpha} have analytic forms, the constitutive law yields an easily differentiable expression for the major loop. Hysteresis curves computed from this constitutive law are shown to be in good agreement with experiments. Calculations of the critical current densities and equilibrium magnetization for the case in which the derivatives are neglected, i.e., the Bean model with J{sub c} {proportional to} M{sub U} {minus} M{sub L} and M{sub e} {proportional to} M{sub U} + M{sub L}, are compared with J{sub c} and M{sub e} computed using a system of equations that takes into account the first two derivatives of all quantities. Exponential approximations are given for the critical current densities of several samples of Y--Ba--Cu--O at temperatures between 5 K and 60 K. 7 refs., 4 figs., 1 tab.

Hodgdon, M.L.

1990-01-01

331

Cosmic string lensing and closed timelike curves  

NASA Astrophysics Data System (ADS)

In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed timelike curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background radiation). Because of the attractorlike behavior of the closed timelike curve, we argue that this instability is very generic. A single graviton or photon in the vicinity, no matter how soft, is sufficient to bend the strings and prevent the formation of closed timelike curves. We also show that the gravitational lensing due to a moving cosmic string is enhanced by its motion, not suppressed.

Shlaer, Benjamin; Tye, S.-H. Henry

2005-08-01

332

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

PubMed

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

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

2011-04-25

333

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

PubMed

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

Koštál, Vladimír; Renault, David; Rozsypal, Jan

2011-06-27

334

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

335

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

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

336

Measuring flow in non-ideal conditions for short-term projects: Uncertainties associated with the use of stage-discharge rating curves  

NASA Astrophysics Data System (ADS)

We calculated uncertainties on flow rates in small streams.Flow rates were calculated using simulated rating curves derived from reference data.Reference data were obtained from stage and velocity measurements obtained in flumes.Rating curve hysteresis is the first factor in the overall uncertainty.Second factor is the inappropriateness of one mathematical function to describe the relation between stage and flow.

Birgand, François; Lellouche, Guillaume; Appelboom, T. W.

2013-10-01

337

Curve and Surface Interrogation  

Microsoft Academic Search

\\u000a Interrogation is the process of extraction of information from a geometric model. In this chapter we focus on free-form curve and surface\\u000a interrogation. Free form surface, also called sculptured surface, are widely used in scientific and engineering applications.\\u000a For example, the hydrodynamic shape of propeller blades has an important role in marine applications, and the aerodynamic\\u000a shape of turbine blades

Nicholas M. Patrikalakis; Takashi Maekawa

338

Quantization on Curves  

NASA Astrophysics Data System (ADS)

Deformation quantization on varieties with singularities offers perspectives that are not found on manifolds. The Harrison component of Hochschild cohomology, vanishing on smooth manifolds, reflects information about singularities. The Harrison 2-cochains are symmetric and are interpreted in terms of abelian *-products. This paper begins a study of abelian quantization on plane curves over mathbb{C}, being algebraic varieties of the form {mathbb{C}}^2/R, where R is a polynomial in two variables; that is, abelian deformations of the coordinate algebra mathbb{C}[x,y]/(R). To understand the connection between the singularities of a variety and cohomology we determine the algebraic Hochschild (co)homology and its Barr Gerstenhaber Schack decomposition. Homology is the same for all plane curves mathbb{C}[x,y]/R, but the cohomology depends on the local algebra of the singularity of R at the origin. The Appendix, by Maxim Kontsevich, explains in modern mathematical language a way to calculate Hochschild and Harrison cohomology groups for algebras of functions on singular planar curves etc. based on Koszul resolutions.

Frønsdal, Christian; Kontsevich, Maxim

2007-02-01

339

An Improved Technique for dry Soil Moisture Release Curves to Determine Soil Mineralogical and Physical Properties  

NASA Astrophysics Data System (ADS)

Soil moisture release curves (MRC) or moisture sorption isotherms, which relate the amount of water in soil to its water potential or water activity, have many applications in soil physics and geotechnical engineering including determining soil water flow, specific surface area, swelling potential, and clay mineralogy and activity. Although research showing MRC for various soils dates back more than 50 years, limitations with the measurement technique have made developing MRC time consuming and inaccurate, especially in dry soils. Recently, an instrument was developed to create moisture sorption isotherms for various food and pharmaceutical products. The objective of this research was to investigate its use in soils for obtaining MRC in dry soils simply and accurately. Several different soil types were tested in the instrument from pure sand to bentonite and smectite clays. From the MRC of these soils, we were able to develop good correlations between actual and derived clay activity, surface area, and swelling potential. In addition, we were able to see hysteresis in dry soil water uptake for all soils, including sand. According to our tests, this new instrument will provide a powerful tool to investigate several soil physical properties simply and accurately.

Campbell, G. S.; Campbell, C. S.; Cobos, D. R.

2008-12-01

340

Curved microchannels and bacterial streamers  

NASA Astrophysics Data System (ADS)

Bacterial biofilms are commonly identified as microbial communities attached to a surface and encased in a self-secreted extracellular matrix. Due to their increased resistance to antimicrobial agents, biofilms have an enormous impact on health and medicine (e.g., wound healing, implant-associated infections, disease transmission). On the other hand, they constitute a major component of the stream ecosystem by increasing transport of nutrients and retention of suspended particles. In this talk, we present an experimental study of bacterial biofilm development in a microfluidic device. In particular, we show the formation of filamentous structures, or streamers, in curved channels and how these suspended biofilms are linked to the underlying hydrodynamics.

Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

2010-03-01

341

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

342

NPR: The Picture Show  

NSDL National Science Digital Library

National Public Radio's "The Picture Show" photo blog is a great way to avoid culling through the thousands of less interesting and engaging photographs on the web. With a dedicated team of professionals, this blog brings together different posts that profile various sets of photographs that cover 19th century war in Afghanistan, visual memories of WWII, unpublished photographs of JFK's presidential campaign, and abandoned buildings on the islands in Boston Harbor. Visitors can search through previous posts, use social media features to share the photo features with friends, and also sign up to receive new materials via their RSS feed. There's quite a nice mix of material here, and visitors can also comment on the photos and recommend the collection to friends and others.

343

Egg: the Arts Show  

NSDL National Science Digital Library

"Egg is a new TV show about people making art across America" from PBS. This accompanying Website presents excerpts from sixteen episodes of the series, with three more "hatching soon," such as Close to Home, profiling three photographers: Jeanine Pohlhaus, whose pictures document her father's struggle with mental illness; Gregory Crewdson's photos of Lee, Massachusetts; and Joseph Rodriguez's photos of Hispanics in New York City. Excerpts include video clips, gallery listings where the artists' work can be seen, and short interviews with artists. Some episodes also offer "peeps," glimpses of material not shown on TV, such as the Space episode's peep, Shooting Stars, that provides directions for astrophotography, taking photographs of star trails. Other sections of the site are airdates, for local listings; see and do usa, where vacationers can search for art events at their destinations; and egg on the arts, a discussion forum.

344

American History Picture Show  

NSDL National Science Digital Library

In class we read Katie's Picture Show, a book about a girl who discovers art first-hand one day at an art museum in London. She realizes she can climb into the paintings, explore her surroundings, and even solve problems for the subjects of the paintings. As part of our unit on American history, we are going to use art to further learn about some of the important events we have been discussing. Each of these works of art depicts an important event in American History. When you click on a picture, you will be able to see the name of the event as well as the artist who created it. You will be using all three pictures for this assignment.Use the websites ...

Bennion, Ms.

2009-11-23

345

Statistical Tools to Analyze Data Representing a Sample of Curves  

Microsoft Academic Search

The paper is concerned with data representing a sample of smooth curves which can be considered as independent realizations of an underlying biological (chemical, $\\\\ldots$) process. Such samples of curves often possess the following features: There is a typical structural pattern common to all curves of the sample. On the other hand, individual realizations of the typical shape show different

Alois Kneip; Theo Gasser

1992-01-01

346

Observing the yield curve of compacted pack ice  

Microsoft Academic Search

A method for observing the yield curve of compacted pack ice is developed based on the characteristic analysis of the stress field within the pack ice. The analysis shows that the slope of the yield curve is associated with the angle between intersecting linear kinematic features; thus by measuring the intersection angles we can inversely estimate the yield curve. Applying

Keguang Wang

2007-01-01

347

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

348

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

349

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

350

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

351

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

352

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

353

Systematic errors in free energy perturbation calculations due to a finite sample of configuration space: Sample-size hysteresis  

SciTech Connect

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

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

1991-08-22

354

Interpretation of hysteresis behaviour of PI-PS multigraft copolymers by adapting to the dynamic flocculation model.  

SciTech Connect

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

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

2008-01-01

355

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

356

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

357

The Great Cometary Show  

NASA Astrophysics Data System (ADS)

The ESO Very Large Telescope Interferometer, which allows astronomers to scrutinise objects with a precision equivalent to that of a 130-m telescope, is proving itself an unequalled success every day. One of the latest instruments installed, AMBER, has led to a flurry of scientific results, an anthology of which is being published this week as special features in the research journal Astronomy & Astrophysics. ESO PR Photo 06a/07 ESO PR Photo 06a/07 The AMBER Instrument "With its unique capabilities, the VLT Interferometer (VLTI) has created itself a niche in which it provide answers to many astronomical questions, from the shape of stars, to discs around stars, to the surroundings of the supermassive black holes in active galaxies," says Jorge Melnick (ESO), the VLT Project Scientist. The VLTI has led to 55 scientific papers already and is in fact producing more than half of the interferometric results worldwide. "With the capability of AMBER to combine up to three of the 8.2-m VLT Unit Telescopes, we can really achieve what nobody else can do," added Fabien Malbet, from the LAOG (France) and the AMBER Project Scientist. Eleven articles will appear this week in Astronomy & Astrophysics' special AMBER section. Three of them describe the unique instrument, while the other eight reveal completely new results about the early and late stages in the life of stars. ESO PR Photo 06b/07 ESO PR Photo 06b/07 The Inner Winds of Eta Carinae The first results presented in this issue cover various fields of stellar and circumstellar physics. Two papers deal with very young solar-like stars, offering new information about the geometry of the surrounding discs and associated outflowing winds. Other articles are devoted to the study of hot active stars of particular interest: Alpha Arae, Kappa Canis Majoris, and CPD -57o2874. They provide new, precise information about their rotating gas envelopes. An important new result concerns the enigmatic object Eta Carinae. Using AMBER with its high spatial and spectral resolution, it was possible to zoom into the very heart of this very massive star. In this innermost region, the observations are dominated by the extremely dense stellar wind that totally obscures the underlying central star. The AMBER observations show that this dense stellar wind is not spherically symmetric, but exhibits a clearly elongated structure. Overall, the AMBER observations confirm that the extremely high mass loss of Eta Carinae's massive central star is non-spherical and much stronger along the poles than in the equatorial plane. This is in agreement with theoretical models that predict such an enhanced polar mass-loss in the case of rapidly rotating stars. ESO PR Photo 06c/07 ESO PR Photo 06c/07 RS Ophiuchi in Outburst Several papers from this special feature focus on the later stages in a star's life. One looks at the binary system Gamma 2 Velorum, which contains the closest example of a star known as a Wolf-Rayet. A single AMBER observation allowed the astronomers to separate the spectra of the two components, offering new insights in the modeling of Wolf-Rayet stars, but made it also possible to measure the separation between the two stars. This led to a new determination of the distance of the system, showing that previous estimates were incorrect. The observations also revealed information on the region where the winds from the two stars collide. The famous binary system RS Ophiuchi, an example of a recurrent nova, was observed just 5 days after it was discovered to be in outburst on 12 February 2006, an event that has been expected for 21 years. AMBER was able to detect the extension of the expanding nova emission. These observations show a complex geometry and kinematics, far from the simple interpretation of a spherical fireball in extension. AMBER has detected a high velocity jet probably perpendicular to the orbital plane of the binary system, and allowed a precise and careful study of the wind and the shockwave coming from the nova. The stream of results from the VLTI and AMBER

2007-01-01

358

CURVES: Curve evolution for vessel segmentation  

Microsoft Academic Search

The vasculature is of utmost importance in neurosurgery. Direct visualization of images acquired with current imaging modalities, however, cannot provide a spatial representation of small vessels. These vessels, and their branches which show considerable variations, are most important in planning and performing neurosurgical procedures. In planning they provide information on where the lesion draws its blood supply and where it

Liana M. Lorigo; Olivier D. Faugeras; W. Eric L. Grimson; Renaud Keriven; Ron Kikinis; Arya Nabavi; Carl-Fredrik Westin

2001-01-01

359

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

360

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

361

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

362

Hysteresis and phase transitions for one-dimensional and three-dimensional models in shape memory alloys  

NASA Astrophysics Data System (ADS)

By means of the Ginzburg-Landau theory of phase transitions, we study a nonisothermal model to characterize the austenite-martensite transition in shape memory alloys. In the first part of this paper, the one-dimensional model proposed by Berti et al. [``Phase transitions in shape memory alloys: A non-isothermal Ginzburg-Landau model,'' Physica D 239, 95 (2010)] is modified by varying the expression of the free energy. In this way, the description of the phenomenon of hysteresis, typical of these materials, is improved and the related stress-strain curves are recovered. Then, a generalization of this model to the three-dimensional case is proposed and its consistency with the principles of thermodynamics is proven. Unlike other three-dimensional models, the transition is characterized by a scalar valued order parameter J and the Ginzburg-Landau equation, ruling the evolution of J, allows us to prove a maximum principle, ensuring the boundedness of J itself.

Berti, V.; Fabrizio, M.; Grandi, D.

2010-06-01

363

CURVED PHOTON MAPPING: BEYOND THE CURVED RAY TRACING ALGORITHM  

Microsoft Academic Search

Several natural phenomena, such as mirages, are owed to inhomogeneous media in which the index of refraction is not constant, and therefore light travels a curved path. One way to simulate Global Illumination in inhomogeneous media is using a curved ray tracing algorithm, but this approach presents some problems that need to be solved. This paper introduces both a curved

MUÑOZ ORBAÑANOS; GUTIERREZ PEREZ; JIMENEZ CHAPRESTO; SERON ARBELOA; Francisco José

364

Hyperelliptic Curve Cryptosystems: Closing the Performance Gap to Elliptic Curves  

Microsoft Academic Search

For most of the time since they were proposed, it was widely believed that hyperelliptic curve cryptosystems (HECC) carry a substantial performance penalty compared to elliptic curve cryptosystems (ECC) and are, thus, not too attractive for practical applications. Only quite recently improvements have been made, mainly restricted to curves of genus 2. The work at hand advances the state-of-the- art

Jan Pelzl; Thomas J. Wollinger; Jorge Guajardo; Christof Paar

2003-01-01

365

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

366

A two-dimensional adsorption kinetic model for thermal hysteresis activity in antifreeze proteins  

NASA Astrophysics Data System (ADS)

Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs), collectively abbreviated as AF(G)Ps, are synthesized by various organisms to enable their cells to survive in subzero environments. Although the AF(G)Ps are markedly diverse in structure, they all function by adsorbing to the surface of embryonic ice crystals to inhibit their growth. This adsorption results in a freezing temperature depression without an appreciable change in the melting temperature. The difference between the melting and freezing temperatures, termed thermal hysteresis (TH), is used to detect and quantify the antifreeze activity. Insights from crystallographic structures of a number of AFPs have led to a good understanding of the ice-protein interaction features. Computational studies have focused either on verifying a specific model of AFP-ice interaction or on understanding the protein-induced changes in the ice crystal morphology. In order to explain the origin of TH, we propose a novel two-dimensional adsorption kinetic model between AFPs and ice crystal surfaces. The validity of the model has been demonstrated by reproducing the TH curve on two different ?-helical AFPs upon increasing the protein concentration. In particular, this model is able to accommodate the change in the TH behavior observed experimentally when the size of the AFPs is increased systematically. Our results suggest that in addition to the specificity of the AFPs for the ice, the coverage of the AFPs on the ice surface is an equally necessary condition for their TH activity.

Li, Q. Z.; Yeh, Y.; Liu, J. J.; Feeney, R. E.; Krishnan, V. V.

2006-05-01

367

Quantum curves and Script D-modules  

NASA Astrophysics Data System (ADS)

In this article we continue our study of chiral fermions on a quantum curve. This system is embedded in string theory as an I-brane configuration, which consists of D4 and D6-branes intersecting along a holomorphic curve in a complex surface, together with a B-field. Mathematically, it is described by a holonomic Script D-module. Here we focus on spectral curves, which play a prominent role in the theory of (quantum) integrable hierarchies. We show how to associate a quantum state to the I-brane system, and subsequently how to compute quantum invariants. As a first example, this yields an insightful formulation of (double scaled as well as general Hermitian) matrix models. Secondly, we formulate c = 1 string theory in this language. Finally, our formalism elegantly reconstructs the complete dual Nekrasov-Okounkov partition function from a quantum Seiberg-Witten curve.

Dijkgraaf, Robbert; Hollands, Lotte; Su?kowski, Piotr

2009-11-01

368

Asymmetry Dependence of the Nuclear Caloric Curve  

NASA Astrophysics Data System (ADS)

A basic feature of the nuclear equation of state is not yet understood: the dependence of the nuclear caloric curve on the neutron-proton asymmetry. Predictions of theoretical models differ on the magnitude and even the sign of this dependence. In this work, the nuclear caloric curve is examined for fully reconstructed quasi-projectiles around mass A = 50. Two independent thermometers, the momentum quadrupole fluctuation thermometer and the Albergo yield ratio thermometer, are used to extract the caloric curve. For both methods, the caloric curve extracted shows that the temperature varies linearly with quasi-projectile asymmetry For the momentum quadrupole fluctuation thermometer, an increase in asymmetry of 0.15 units corresponds to a decrease in temperature on the order of 1 MeV. These results also highlight the importance of a full quasi-projectile reconstruction in the study of thermodynamic properties of hot nuclei.

McIntosh, A. B.; Bonasera, A.; Cammarata, P.; Hagel, K.; Heilborn, L.; Kohley, Z.; Mabiala, J.; May, L. W.; Marini, P.; Raphelt, A.; Souliotis, G. A.; Wuenschel, S.; Zarrella, A.; Yennello, S. J.

2013-03-01

369

Dynamic Stability of Curved Panels with Cutouts  

NASA Astrophysics Data System (ADS)

The parametric instability behaviour of curved panels with cutouts subjected to in-plane static and periodic compressive edge loadings are studied using finite element analysis. The first order shear deformation theory is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to Sanders' first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. The effects of static and dynamic load factors, geometry, boundary conditions and the cutout parameters on the principal instability regions of curved panels with cutouts are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry and load parameters on the stability boundaries. Results for plates are also presented as special cases and are compared with those available in the literature. Copyright 2002 Elsevier Science Ltd.

Sahu, S. K.; Datta, P. K.

2002-04-01

370

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

371

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

372

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

373

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

374

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

375

New Binary Systems With Asymmetric Light Curves  

NASA Astrophysics Data System (ADS)

We present the results of investigation of the light curves of 27 newly discovered binary systems. Among the examined curves, there were 10 curves with statistically significant asymmetry of maximums, according the 3? criterion for the difference between the maximal brightness. Half of these 10 curves have a higher first maximum, another half the second one. Two of these 10 curves, USNO-B1.0 1629-0064825 = VSX J052807.9+725606 and USNO-B1.0 1586-0116785, show the largest difference between magnitudes in maxima. The star VSX J052807.9+725606 also shows the secondary minimum, which is shifted from the phase ? = 0.5. The shape of the curve argues that the physical processes of this star could be close to that of well known short periodic binary system V361 Lyr, which has a spot on the surface of one star of the system. Another star, USNO-B1.0 1586-0116785, probably has a cold spot, or several spots, in the photosphere of one of the components.

Virnina, Natalia A.

2010-12-01

376

Relative permeability hysteresis and capillary trapping characteristics of supercritical CO2/brine systems: An experimental study at reservoir conditions  

NASA Astrophysics Data System (ADS)

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

Akbarabadi, Morteza; Piri, Mohammad

2013-02-01

377

Degree formulae for offset curves  

Microsoft Academic Search

In this paper, we present three different formulae for computing the degree of the offset of a real irreducible affine plane curve C given implicitly, and we see how these formulae particularize to the case of rational curves. The first formula is based on an auxiliary curve, called S, that is defined depending on a non-empty Zariski open subset of

Fernando San Segundo; J. Rafael Sendra

2005-01-01

378

Enumerating singular curves on surfaces  

Microsoft Academic Search

We enumerate the singular algebraic curves in a complete linear system on a smooth projective surface. The system must be suitably ample in a rather precise sense. The curves may have up to eight nodes, or a triple point of a given type and up to three nodes. The curves must also pass through appropriately many general points. The number

Steven Kleiman; Ragni Piene

1999-01-01

379

Titration Curves: Fact and Fiction.  

ERIC Educational Resources Information Center

|Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

Chamberlain, John

1997-01-01

380

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

381

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

382

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

383

Multipulse phase resetting curves  

NASA Astrophysics Data System (ADS)

In this paper, we introduce and study systematically, in terms of phase response curves, the effect of dual-pulse excitation on the dynamics of an autonomous oscillator. Specifically, we test the deviations from linear summation of phase advances resulting from two small perturbations. We analytically derive a correction term, which generally appears for oscillators whose intrinsic dimensionality is >1. The nonlinear correction term is found to be proportional to the square of the perturbation. We demonstrate this effect in the Stuart-Landau model and in various higher dimensional neuronal models. This deviation from the superposition principle needs to be taken into account in studies of networks of pulse-coupled oscillators. Further, this deviation could be used in the verification of oscillator models via a dual-pulse excitation.

Krishnan, Giri P.; Bazhenov, Maxim; Pikovsky, Arkady

2013-10-01

384

Understanding curved detonation waves  

SciTech Connect

The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

Bukiet, B.G. (New Jersey Inst. of Tech., Newark, NJ (United States)); Lackner, K.S.; Menikoff, R. (Los Alamos National Lab., NM (United States))

1993-01-01

385

Understanding curved detonation waves  

SciTech Connect

The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

Bukiet, B.G. [New Jersey Inst. of Tech., Newark, NJ (United States); Lackner, K.S.; Menikoff, R. [Los Alamos National Lab., NM (United States)

1993-06-01

386

Generating Resources Supply Curves.  

SciTech Connect

This report documents Pacific Northwest supply curve information for both renewable and other generating resources. Resources are characterized as ''Renewable'' and ''Other'' as defined in section 3 or the Pacific Northwest Electric Power Planning and Conservation Act. The following resources are described: renewable: (cogeneration; geothermal; hydroelectric (new); hydroelectric (efficiency improvement); solar; and wind); other (nonrenewable generation resources: coal; combustion turbines; and nuclear. Each resource has the following information documented in tabular format: (1) Technical Characteristics; (2) Costs (capital and O and M); (3) Energy Distribution by Month; and (4) Supply Forecast (energy). Combustion turbine (CT) energy supply is not forecasted because of CT's typical peaking application. Their supply is therefore unconstrained in order to facilitate analysis of their operation in the regional electrical supply system. The generic nuclear resource is considered unavailable to the region over the planning horizon.

United States. Bonneville Power Administration. Division of Power Resources Planning.

1985-07-01

387

Holomorphic curves from matrices  

NASA Astrophysics Data System (ADS)

Membranes holomorphically embedded in flat non-compact space are constructed in terms of the degrees of freedom of an infinite collection of 0-branes. To each holomorphic curve we associate infinite-dimensional matrices which are static solutions to the matrix theory equations of motion, and which can be interpreted as the matrix theory representation of the holomorphically embedded membrane. The problem of finding such matrix representations can be phrased as a problem in geometric quantization, where ?~lP3/R plays the role of the Planck constant and parametrizes families of solutions. The concept of Bergman projection is used as a basic tool, and a local expansion for the action of the projection in inverse powers of curvature is derived. This expansion is then used to compute the required matrices perturbatively in ?. The first two terms in the expansion correspond to the standard geometric quantization result and to the result obtained using the metaplectic correction to geometric quantization.

Cornalba, Lorenzo; Taylor, Washington, IV

1998-12-01

388

Amplitude and frequency dependence of hysteresis loss in a magnet-superconductor levitation system  

SciTech Connect

Using an electromagnetically controlled mechanical pendulum, we measured the energy loss for different amplitudes in a magnetic levitation system that contained high temperature superconductors (HTSs). Two procedures were followed to measure losses at 77 K for frequencies of 93.8 mHz to 80 Hz. In the first procedure, the distance between the permanent magnet and the HTS levitator was the same as that during (field) cooling. In the second procedure, the magnet was lowered (after cooling) closer to the HTS levitator before the measurements were performed. The experimental data show that these two procedures give essentially the same results at the same distance despite different cooling (and magnetization) histories for melt-textured YBaCuO levitators, and the frequency-independent energy loss is a power-law function of amplitude. We attribute the energy loss to magnetic hysteresis in the superconductor. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Yang, Z.J.; Hull, J.R.; Mulcahy, T.M. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Rossing, T.D. [Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)

1995-08-01

389

Characterization upon electrical hysteresis and thermal diffusion of TiAl3O x dielectric film  

NASA Astrophysics Data System (ADS)

In this paper, we have investigated the electrical properties of TiAl3O x film as electrical gate insulator deposited by pulsed laser deposition and presented a simple method to describe the thermal diffusion behaviors of metal atoms at TiAl3O x /Si interfacial region in detail. The TiAl3O x films show obvious electrical hysteresis by the capacitance-voltage measurements after post-annealing treatment. By virtue of the diffusion models composed of TiAl3O x film and silicon, the diffusion coefficient and the diffusion activation energy of the Ti and Al atoms are extracted. It is valuable to further investigate the pseudobinary oxide system in practice. PACS: 77.55.-g; 81.15.Fg; 81.40.Gh.

Shi, Lei; Liu, Zhiguo

2011-10-01

390

Curvature-dependent metastability of the solid phase and the freezing-melting hysteresis in pores.  

PubMed

We recapitulate and generalize the concept of the freezing-melting hysteresis that attributes this phenomenon to a free-energy barrier between metastable and stable states of pore-filling material. In a phenomenological description, we show that under commonly encountered conditions, this renders the freezing-point depression DeltaTf defined by the surface-to-volume ratio S/V, whereas the melting-point depression DeltaTm, by the mean curvature kappa of the pore surface, with DeltaTm/DeltaTf =2kappa(V/S). Employing 1H NMR cryoporometry, we experimentally demonstrate the linear correlation between DeltaTm and DeltaTf for several liquids with different DeltaTf,m imbibed in controlled pore glasses. The results compare favorably to the morphological properties of the glasses determined by other techniques. Our findings suggest a simple method for analyzing the pore morphology from the observed phase transition temperatures. PMID:16486162

Petrov, Oleg; Furó, István

2006-01-31

391

Spectral properties of the Preisach hysteresis model with random input. I. General results  

NASA Astrophysics Data System (ADS)

We derive exact results for the spectral density S(?) of the output of the Preisach model, a standard model for complex, nonlocal hysteresis. We obtain general results for uncorrelated input signals with arbitrary input and Preisach densities. It is shown analytically that uncorrelated input signals are transformed into output exhibiting long-time correlations. For the simplest example of uniform input and Preisach distributions we prove that correlations decay asymptotically with a t-3 power law corresponding to a logarithmic low frequency divergence of the second derivative of the spectrum S(?) . A simpler expression for symmetric Preisach models is also obtained, which is discussed in detail in Part II, showing that long-time tails or even 1/f noise are general features of this class of models.

Radons, Günter

2008-06-01

392

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

393

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

394

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

395

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

396

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

397

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

398

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

399

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

400

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

401

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

402

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

403

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

404

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

405

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

406

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

407

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

408

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

409

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

410

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

411

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

412

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

413

Automated reasoning about cubic curves.  

SciTech Connect

It is well known that the n-ary morphisms defined on projective algebraic curves satisfy some strong local-to-global equational rules of derivation not satisfied in general by universal algebras. For example, every rationally defined group law on a cubic curve must be commutative. Here we extract from the geometry of curves a first order property (gL) satisfied by all morphisms defined on these curves such that the equational consequences known for projective curves can be derived automatically from a set of six rules (stated within the first-order logic with equality). First, the rule (gL) is implemented in the theorem-proving program Otter. Then we use Otter to automatically prove some incidence theorems on projective curves without any further reference to the underlying geometry or topology of the curves.

Padmanabhan, R.; McCune, W.; Mathematics and Computer Science; Univ. of Manitoba

1995-01-01

414

The Relevance and Implications of the Environmental Kuznets Curve Under Stock Effects and NonLinearities: A Hysteresis Based Approach  

Microsoft Academic Search

A number of studies in the past have come up in order to explain and verify the observation made by Grossman and Kruger that that there may exist an inverted U-shaped relationship between environmental pollution and income. While some studies have found this relationship to hold true for certain pollutants, other studies have rejected this hypothesis based upon empirical observations

Ram Ranjan; James S. Shortle; Elizabeth P. Marshall

2003-01-01

415

Feature grid neural networks for curve partitioning  

Microsoft Academic Search

Presents a neural network method for partitioning image curves into perceptual entities called generic curve segments (GCSs). GCSs are perceptual classes of primitive curve objects, which are qualitative descriptors for grouping curve shapes. The success of GCS classification and curve grouping relies on correctly locating curve partitioning points (CPPs), i.e. points from where the curves are broken down into GCSs.

Mao Tan; Qigang Gao

2000-01-01

416

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

417

Symmetries of curved superspace  

NASA Astrophysics Data System (ADS)

The formalism to determine (conformal) isometries of a given curved super-space was elaborated almost two decades ago in the context of the old minimal formulation for {N}=1 supergravity in four dimensions (4D). This formalism is universal, for it may readily be generalized to supersymmetric backgrounds associated with any supergravity theory formulated in superspace. In particular, it has already been used to construct rigid supersymmetric field theories in 5D {N}=1 , 4D {N}=2 and 3D ( p, q) anti-de Sitter super-spaces. In the last two years, there have appeared a number of publications devoted to the construction of supersymmetric backgrounds in off-shell 4D {N}=1 supergravity theories using component field considerations. Here we demonstrate how to read off the key results of these recent publications from the more general superspace approach developed in the 1990s. We also present a universal superspace setting to construct supersymmetric backgrounds, which is applicable to any of the known off-shell formulations for {N}=1 supergravity. This approach is based on the realizations of the new minimal and non-minimal supergravity theories as super-Weyl invariant couplings of the old minimal supergravity to certain conformal compensators.

Kuzenko, Sergei M.

2013-03-01

418

Communities, clustering phase transitions, and hysteresis: pitfalls in constructing network ensembles.  

PubMed

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

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

2010-04-27

419

Modeling the Relationship Between Neutron Counting Rates and Sunspot Numbers Using the Hysteresis Effect  

NASA Astrophysics Data System (ADS)

Several studies show that temporal variations in the Galactic cosmic ray (GCR) intensity display a distinct 11-year periodicity due to solar modulation of the galactic cosmic rays in the heliosphere. The 11-year periodicity of GCRs is inversely proportional to, but out of phase with, the 11-year solar cycle, implying that there is a time lag between actual solar cycle and the GCR intensity, which is known as the hysteresis effect. In this study, we use the hysteresis effect to model the relationship between neutron counting rates (NCRs), an indicator of the GCR intensity, and sunspot numbers (SSNs) over the period that covers the last four solar cycles (20, 21, 22, and 23). Both linear and ellipse models were applied to SSNs during odd and even cycles in order to calculate temporal variations of NCRs. We find that ellipse modeling provides higher correlation coefficients for odd cycles compared to linear models, e.g. 0.97, 0.97, 0.92, and 0.97 compared to 0.69, 0.72, 0.53, and 0.68 for data from McMurdo, Swarthmore, South Pole, and Thule neutron monitors, respectively, during solar cycle 21 with overall improvement of 31 % for odd cycles. When combined to a continuous model, the better correlation observed for the odd cycles increases the overall correlation between observed and modeled NCRs. The new empirical model therefore provides a better representation of the relationship between NCRs and SSNs. A major goal of the ongoing research is to use the new non-linear empirical model to reconstruct SSNs on annual time scales prior to 1610, where we do not have observational records of SSNs, based on changes in NCRs reconstructed from 10Be in ice cores.

Inceoglu, F.; Knudsen, M. F.; Karoff, C.; Olsen, J.

2013-09-01

420

Hysteresis and two-dimensional nonlinear wave propagation in Berea Sandstone  

NASA Astrophysics Data System (ADS)

We have further developed a two-dimensional endochronic constitutive model applicable to rock in the intermediate strain regime, i.e., approximately 10-6 to 10-3, where nonlinear losses, pulse distortion, and harmonic distortions have been documented in the laboratory. An accurate and efficient computation algorithm has been established and used to fit a set of triaxial laboratory data on Berea Sandstone, obtained by G. N. Boitnott of New England Research, Inc., including nonlinear hysteresis for both hydrostatic compression and shear deformation. The constitutive model has been incorporated into a two-dimensional pseudospectral scheme for simulating nonlinear wave propagation. We compare our numerical pseudospectral scheme with the perturbation solutions to nonlinearly elastic plane wave propagation and find that the two solutions are in close agreement. Applying the numerical scheme to the endochronic constitutive model for Berea Sandstone, we find the following results, which confirm and extend previous results obtained with a one-dimensional model: (1) nonlinear propagation from a monochromatic source excites odd harmonics of the source frequency, (2) the interaction of two monochromatic wave fields leads to energy transfer to other bands corresponding to various combinations of the two source frequencies, (3) amplitudes of the harmonics change with distance and show a trade-off between nonlinearity, intrinsic attenuation (hysteresis), and geometrical spreading, (4) for a broadband pressure source, energy is transferred from the principal band to a higher band at the expense of the components at intermediate frequencies; this is diagnostic of nonlinear interactions, and (5) the harmonic amplitude and energy transfer increase nonlinearly with strain amplitude; i.e., higher strain levels lead to higher energy exchange. These simulations of harmonic generation, interaction, and band expansion, based on a model developed from quasistatic experimental observations, agree with dynamic experimental observations.

Xu, Heming; Day, Steven M.; Minster, Jean-Bernard H.

2000-03-01

421

Infiltration of Liquid Droplets Into Porous Media: Effects of Dynamic Contact Angle and Contact Angle Hysteresis  

NASA Astrophysics Data System (ADS)

Infiltration of liquid droplets into dry porous media occurs when rain drops fall onto soil, when accidentally spilling organic liquid (e.g., gasoline and chlorinated solvents) onto ground, or when aerosol pesticides are not intercepted by the vegetation and then released to soils. If harmful chemicals are released from the droplet into the atmosphere through evaporation, it is important to know the time of infiltration. We developed a theory for infiltration, which accounts for a general model for the dynamic contact angle between the droplet and the porous medium as well as contact angle hysteresis. Our theory assumes the droplet to have the shape of a spherical cap and the pressure within the droplet to be uniform. The theory shows that droplet infiltration involves three phases due to contact angle hysteresis: (1) an increasing drawing area (IDA) phase during which the interface between the droplet and the porous medium increases, (2) a constant drawing area (CDA) phase during which the contact line of the droplet remains pinned, and (3) a decreasing drawing area (DDA) phase. We find that infiltration always consists of a cascade process formed by the IDA, CDA, and DDA phases, where the entire process may begin or end in any of the three phases. The entire process is formulated with four nondimensional parameters: three contact angles (initial, advancing, and receding) and a porous permeability parameter that depends on porous medium geometry. The total time of infiltration and the time dependence of drawing area are critically affected by the occurrence of the IDA, CDA, and DDA phases as well as by the permeability. In general, the IDA and DDA phases are described by integro-differential equations. With ordinary differential equations (ODEs), we are able to approximate the IDA phase and to describe exactly infiltration processes that starts out with the CDA or DDA phase.

Hilpert, M.

2008-12-01

422

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

423

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

424

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

425

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

426

Hysteresis phenomena and multipulse formation of a dissipative system in a passively mode-locked fiber laser  

NASA Astrophysics Data System (ADS)

A model describing the dissipative soliton evolution in a passively mode-locked fiber laser is proposed by using the nonlinear polarization rotation technique and the spectral filtering effect. It is numerically found that the laser alternately evolves on the stable and unstable mode-locking states as a function of the pump strength. Numerical simulations show that the passively mode-locked fiber lasers with large net normal dispersion can operate on multiple pulse behavior and hysteresis phenomena. The experimental observations confirm the theoretical predictions. The theoretical and experimental results achieved are qualitatively distinct from those observed in net-anomalous-dispersion conventional-soliton fiber lasers.

Liu, Xueming

2010-02-01

427

Calculation of radioimmunoassay standard curves  

Microsoft Academic Search

A method for calculating radioimmunoassay standard curves, based on the theory of Ekins et al., is described. Because a four-parameter model is used, nonlinear standard curves are the result. The calibration curve is fitted to the measured standard points by means of a weighted least-squares method. The program based on this model can be easily processed on a desk-top calculator.

A. J. Naus; P. S. Kuppens; A. Borst

1977-01-01

428

Photosynthetic light-response curves  

Microsoft Academic Search

Gradients in photosynthetic capacity through the leaf affect the shape of the irradiance-response curve. These gradients in photosynthetic capacity were manipulated by restraining leaves in different orientations. The shape or curvature of the light-response curve can be defined by T, where T=0 is a rectangular hyperbola and T=1 is a Blackman curve. Horizontal leaves had the highest T values when

J. R. Evans; I. Jakobsen; E. Ögren

1993-01-01

429

Synthetic RR Lyrae velocity curves  

SciTech Connect

An amplitude correlation between the pulsation velocity curves and visual light curves of ab-type RR Lyrae stars is derived from a large number of RR Lyrae that have high-precision radial-velocity and photometric data. Based on the determined AVp, AV ralation, a synthetic radial-velocity curve for a typical ab-type RR Lyrae star is constructed. This would be of particular use in determining the systemic velocities of RR Lyrae. 17 refs.

Liu, Tianxing (California Univ., Los Angeles (USA) Boston Univ., MA (USA))

1991-02-01

430

Synthetic RR Lyrae velocity curves  

NASA Astrophysics Data System (ADS)

An amplitude correlation between the pulsation velocity curves and visual light curves of ab-type RR Lyrae stars is derived from a large number of RR Lyrae that have high-precision radial-velocity and photometric data. Based on the determined AVp, AV ralation, a synthetic radial-velocity curve for a typical ab-type RR Lyrae star is constructed. This would be of particular use in determining the systemic velocities of RR Lyrae.

Liu, Tianxing

1991-02-01

431

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

432

10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH SUPPORT A DEEP CURVE IN THE LONGEST SECTION OF THE WALL, LOOKING SOUTH-SOUTHWEST - Rock Wall, North side of Battle Creek Canyon, Shingletown, Shasta County, CA

433

3. AERIAL VIEW LOOKING NORTHEAST, SHOWING ERECTING SHOP, MILLWRIGHT SHOP, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. AERIAL VIEW LOOKING NORTHEAST, SHOWING ERECTING SHOP, MILLWRIGHT SHOP, AND FITTING SHOP. UPPER RACE CURVES IN FOREGROUND. - Rogers Locomotive & Machine Works, Spruce & Market Streets, Paterson, Passaic County, NJ

434

Can telomere shortening explain sigmoidal growth curves?  

Microsoft Academic Search

A general branching process model is proposed to describe the shortening of telomeres in eukaryotic chromosomes. The model is flexible and incorporates many special cases to be found in the literature. In particular, we show how telomere shortening can give rise to sigmoidal growth curves, an idea first expressed by Portugal et al. [A computational model for telomere-dependent cell-replicative aging,

Peter Olofsson

2010-01-01

435

Analytic Light Curves for Planetary Transit Searches  

Microsoft Academic Search

We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we show that the exact light curve can be well approximated by assuming the region of the star blocked by the planet has constant surface brightness.

Kaisey Mandel; Eric Agol

2002-01-01

436

Human Platelet Aggregation Curve and Oral Contraception  

Microsoft Academic Search

In a series of in vitro experiments, the authors investigated the different aspects of the aggregation curves of human blood platelets taken from a group of women who received oral contraceptives, another group of women who did not receive oral contraceptives and a group of men. The platelets were subjected to ADP stimulation. The authors showed that at the lower

C. M. D. Montanari; A. Vittoria; U. Rossi; P. Sala

1979-01-01

437

On the Melting Curve at High Pressures  

Microsoft Academic Search

Summary The asymptotic behaviour of the inclting curves for substances with close- packed structures is analysed by means of Monte Carlo caIculations on model systems of hard spheres. The Kraut--Kennedy melting law does not show the correct asymptotic behaviour. On this basis some recent results on the physics of the Earth's core are rejected. Higgins & Kennedy (1971) have estimated

Enzo Boschik

1974-01-01

438

Phase-transient Hierarchical Turbulence as an Energy Correlation Generator of Blazar Light Curves  

NASA Astrophysics Data System (ADS)

Hierarchical turbulent structure constituting a jet is considered to reproduce energy-dependent variability in blazars, particularly, the correlation between X- and gamma-ray light curves measured in the TeV blazar Markarian 421. The scale-invariant filaments are featured by the ordered magnetic fields that involve hydromagnetic fluctuations serving as electron scatterers for diffusive shock acceleration, and the spatial size scales are identified with the local maximum electron energies, which are reflected in the synchrotron spectral energy distribution (SED) above the near-infrared/optical break. The structural transition of filaments is found to be responsible for the observed change of spectral hysteresis.

Honda, Mitsuru

2008-03-01

439

The Stäckel systems and algebraic curves  

NASA Astrophysics Data System (ADS)

We show how the Abel-Jacobi map provides all the principal properties of an ample family of integrable mechanical systems associated to hyperelliptic curves. We prove that derivative of the Abel-Jacobi map is just the Stäckel matrix, which determines n-orthogonal curvilinear coordinate systems in a flat space. The Lax pairs, r-matrix algebras and explicit form of the flat coordinates are constructed. An application of the Weierstrass reduction theory allows us to construct several flat coordinate systems on a common hyperelliptic curve and to connect among themselves different integrable systems on a single phase space.

Tsiganov, A. V.

1999-01-01

440

Phase Curves of Jovian Trojan Asteroids  

NASA Astrophysics Data System (ADS)

The provenance of the Jovian Trojan asteroids, found at the stable L4 and L5 Lagrange points of Jupiter's orbit, has long been a topic of debate. For decades most researchers believed that they formed in situ, but recent evidence, both theoretical and observational, suggests that the Trojans may have formed at greater heliocentric distances. The observational evidence is based primarily upon the similar spectral properties and albedos of large Trojans to those of cometary nuclei (e.g. Abell et al. 2005). The phase curve--the variation of an asteroid's light with phase angle--carries information about nature and texture of the surface. The two Trojan asteroids whose phase curves have been well studied to data appear to show no strong surge in brightness near zero phase angle, unlike most dark main belt asteroids. We propose to determine phase curves for five additional Trojan asteroids.

French, Linda M.; Lederer, Susan; Stephens, Robert

2010-02-01

441

Asymmetry dependence of the nuclear caloric curve  

NASA Astrophysics Data System (ADS)

A basic feature of the nuclear equation of state is not yet understood: the dependence of the nuclear caloric curve on the neutron–proton asymmetry. Predictions of theoretical models differ on the magnitude and even the sign of this dependence. In this work, the nuclear caloric curve is examined for fully reconstructed quasi-projectiles around mass A=50. The caloric curve extracted with the momentum quadrupole fluctuation thermometer shows that the temperature varies linearly with quasi-projectile asymmetry N?ZA. An increase in asymmetry of 0.15 units corresponds to a decrease in temperature on the order of 1 MeV. These results also highlight the importance of a full quasi-projectile reconstruction in the study of thermodynamic properties of hot nuclei.

McIntosh, A. B.; Bonasera, A.; Cammarata, P.; Hagel, K.; Heilborn, L.; Kohley, Z.; Mabiala, J.; May, L. W.; Marini, P.; Raphelt, A.; Souliotis, G. A.; Wuenschel, S.; Zarrella, A.; Yennello, S. J.

2013-02-01

442

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

443

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

444

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

445

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

446

Lame curves with bad reduction  

Microsoft Academic Search

Lame curves are a particular class of elliptic curves (with a torsion point attached to them) which naturally arise when studying Lame operators with finite monodromy. They can be realized as covers of the projective line unramified outside three points and can be defined over number fields. This paper investigates their p-adic properties. The main ingredient is formal\\/rigid geometry and

Leonardo Zapponi

2006-01-01

447

Growth curves for preterm infants  

Microsoft Academic Search

The commonly used growth curves for preterm infants are four decades old and may not be suitable for the current population. Uncertainty exists regarding the most suitable curves for monitoring the growth of preterm infants. While intrauterine growth rate appears to be the ideal growth that needs to be attained by the preterm infants, it may not be feasible given

Shripada C. Rao; Jeffrey Tompkins

2007-01-01

448

Parsimonious Modeling of Yield Curves  

Microsoft Academic Search

This paper introduces a parametrically parsimonious model for yield curves that has the ability to represent the shapes generally associated with yield curves: monotonic, humped, and S-shaped. The authors find that the model explains 96 percent of the variation in bill yields across maturities during the period 1981-83. The movement of the parameters through time reflects and confirms a change

Charles R. Nelson; Andrew F. Siegel

1987-01-01

449

Orthogonal curvilinear coordinate systems corresponding to singular spectral curves  

Microsoft Academic Search

We study the limiting case of the Krichever construction of orthogonal curvilinear coordinate systems when the spectral curve\\u000a becomes singular. We show that when the curve is reducible and all its irreducible components are rational curves, the construction\\u000a procedure reduces to solving systems of linear equations and to simple computations with elementary functions. We also demonstrate\\u000a how well-known coordinate systems,

A. E. Mironov; I. A. Taimanov

2006-01-01

450

High accuracy Hermite approximation for space curves in R d  

Microsoft Academic Search

In this article, it is shown that a space curve in Rd can be approximated by a piecewise polynomial curve of degree m with order (m+1)+?(m+1)\\/(2d?1)? rather than m+1. Moreover, we show that the optimal order (m+1)+?(m?1)\\/(d?1)? is possible for a particular set of curves of nonzero measure. Analogous results were shown to be true for Taylor polynomial interpolation in

Abedallah Rababah

2007-01-01

451

Light saturation curves show competence of the water splitting complex in inactive Photosystem II reaction centers  

Microsoft Academic Search

Photosystem II complexes of higher plants are structurally and functionally heterogeneous. While the only clearly defined structural difference is that Photosystem II reaction centers are served by two distinct antenna sizes, several types of functional heterogeneity have been demonstrated. Among these is the observation that in dark-adapted leaves of spinach and pea, over 30% of the Photosystem II reaction centers

Ladislav Nedbal; Cynthia Gibas; John Whitmarsh

1991-01-01

452

New explicit conditions of elliptic curve traces for FR-reduction  

Microsoft Academic Search

In this paper, we aim at characterizing elliptic curve traces by FR-reduction and investigate explicit conditions of traces vulnerable or secure against FR-reduction. We show new explicit conditions of elliptic curve traces for FRreduction. We also present algorithms to construct such elliptic curves, which have relation to famous number theory problems. key words: elliptic curve cryptosystems, trace, FRreduction 1. Introduction

Atsuko MIYAJI; Masaki NAKABAYASHI; Shunzou TAKANO

2001-01-01

453

Temperature response of soil respiration in a Chinese pine plantation: hysteresis and seasonal vs. diel Q10.  

PubMed

Although the temperature response of soil respiration (Rs ) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs -temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts ) exerted a strong control over Rs , with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m(-2) s(-1), respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts , with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts , which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required. PMID:23469089

Jia, Xin; Zha, Tianshan; Wu, Bin; Zhang, Yuqing; Chen, Wenjing; Wang, Xiaoping; Yu, Haiqun; He, Guimei

2013-02-28

454

Temperature Response of Soil Respiration in a Chinese Pine Plantation: Hysteresis and Seasonal vs. Diel Q10  

PubMed Central

Although the temperature response of soil respiration (Rs) has been studied extensively, several issues remain unresolved, including hysteresis in the Rs–temperature relationship and differences in the long- vs. short-term Rs sensitivity to temperature. Progress on these issues will contribute to reduced uncertainties in carbon cycle modeling. We monitored soil CO2 efflux with an automated chamber system in a Pinus tabulaeformis plantation near Beijing throughout 2011. Soil temperature at 10-cm depth (Ts) exerted a strong control over Rs, with the annual temperature sensitivity (Q10) and basal rate at 10°C (Rs10) being 2.76 and 1.40 µmol m?2 s?1, respectively. Both Rs and short-term (i.e., daily) estimates of Rs10 showed pronounced seasonal hysteresis with respect to Ts, with the efflux in the second half of the year being larger than that early in the season for a given temperature. The hysteresis may be associated with the confounding effects of microbial population dynamics and/or litter input. As a result, all of the applied regression models failed to yield unbiased estimates of Rs over the entire annual cycle. Lags between Rs and Ts were observed at the diel scale in the early and late growing season, but not in summer. The seasonality in these lags may be due to the use of a single Ts measurement depth, which failed to represent seasonal changes in the depth of CO2 production. Daily estimates of Q10 averaged 2.04, smaller than the value obtained from the seasonal relationship. In addition, daily Q10 decreased with increasing Ts, which may contribute feedback to the climate system under global warming scenarios. The use of a fixed, universal Q10 is considered adequate when modeling annual carbon budgets across large spatial extents. In contrast, a seasonally-varying, environmentally-controlled Q10 should be used when short-term accuracy is required.

Jia, Xin; Zha, Tianshan; Wu, Bin; Zhang, Yuqing; Chen, Wenjing; Wang, Xiaoping; Yu, Haiqun; He, Guimei

2013-01-01

455

New Calibration Methods to Eliminate the Non-Ideal Effect of Drift and Hysteresis in All-Solid-State Potassium Electrode  

Microsoft Academic Search

The object of this study is to develop a non-ideal effects calibration method combining of hardware and soft- ware, and apply this calibration methods to an all-solid-state potassium electrode. In the hardware method, the calibration circuit owning drift and hysteresis calibration functions are developed to improve the accuracy of the measurement system. The experimental results show that both drift and

Jui-Fu Cheng; Jung-Chuan Chou; Tai-Ping Sun; Shen-Kan Hsiung; Hui-Ling Kao

2011-01-01

456

Asymmetry Dependence of Nuclear Caloric Curves  

NASA Astrophysics Data System (ADS)

Quasi-projectile sources produced in collisions of 70Zn+70Zn, 64Zn+64Zn and 64Ni+64Ni at E/A=35MeV have been reconstructed using the charged particles and free neutrons measured in the NIMROD-ISiS 4-pi detector. Equilibrated sources were selected which have a mass A=48-52 and which are on average spherical. Caloric curves for these quasi-projectiles have been extracted with the quadrupole momentum fluctuation thermometer. The caloric curves for the different light charged particle probes show a clear ordering which is consistent with a scenario in which the ``expensive'' particles are emitted preferentially at early times, when the source is hottest. For all light charged particle probes, the caloric curves show a clear dependence on the composition, (N-Z)/A, of the source. For a given excitation (E*/A), the neutron-poor sources exhibit higher temperatures. A consistent but smaller dependence is observed by selecting on the composition of the initial system rather than the composition of the source. The dependence on source composition is also observed in caloric curves extracted with the Albergo yield-ratio thermometer.

McIntosh, A. B.; Bonasera, A.; Galanopoulos, S.; Hagel, K.; Kohley, Z.; May, L.; Shetty, D. V.; Smith, W. B.; Soisson, S. N.; Souliotis, G. A.; Stein, B. C.; Tripathi, R.; Wuenschel, S.; Yennello, S. J.

2012-03-01

457

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

458

Modeling and Fitting Exoplanet Transit Light Curves  

NASA Astrophysics Data System (ADS)

We present a numerical model along with an original fitting routine for the analysis of transiting extra-solar planet light curves. Our light curve model is unique in several ways from other available transit models, such as the analytic eclipse formulae of Mandel & Agol (2002) and Giménez (2006), the modified Eclipsing Binary Orbit Program (EBOP) model implemented in Southworth’s JKTEBOP code (Popper & Etzel 1981; Southworth et al. 2004), or the transit model developed as a part of the EXOFAST fitting suite (Eastman et al. in prep.). Our model employs Keplerian orbital dynamics about the system’s center of mass to properly account for stellar wobble and orbital eccentricity, uses a unique analytic solution derived from Kepler’s Second Law to calculate the projected distance between the centers of the star and planet, and calculates the effect of limb darkening using a simple technique that is different from the commonly used eclipse formulae. We have also devised a unique Monte Carlo style optimization routine for fitting the light curve model to observed transits. We demonstrate that, while the effect of stellar wobble on transit light curves is generally small, it becomes significant as the planet to stellar mass ratio increases and the semi-major axes of the orbits decrease. We also illustrate the appreciable effects of orbital ellipticity on the light curve and the necessity of accounting for its impacts for accurate modeling. We show that our simple limb darkening calculations are as accurate as the analytic equations of Mandel & Agol (2002). Although our Monte Carlo fitting algorithm is not as mathematically rigorous as the Markov Chain Monte Carlo based algorithms most often used to determine exoplanetary system parameters, we show that it is straightforward and returns reliable results. Finally, we show that analyses performed with our model and optimization routine compare favorably with exoplanet characterizations published by groups such as the Keele Astrophysics Group and the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) team.

Millholland, Sarah; Ruch, G. T.

2013-01-01

459

An accurate adaptive parametric curve interpolator for NURBS curve interpolation  

Microsoft Academic Search

In this paper, an adaptive parametric curve interpolator with a real-time look-ahead function is developed for non-uniform\\u000a rational B-spline curves (NURBS) interpolation, which considers the maximum acceleration\\/deceleration of the machine tool.\\u000a In the proposed interpolator, both constant feedrate and high accuracy are achieved while the inconsistency of feedrate is\\u000a reduced dramatically as well. In order to deal with the acceleration\\/deceleration

Daoshan Du; Yadong Liu; Cunliang Yan; Congxin Li

2007-01-01

460

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

461

CurveBall  

NSDL National Science Digital Library

Web site contains java applet which simulates the forces acting on a baseball. The user can change the speed, the spin, the angle and the height of the ball. Additionally, the user can choose from among several ball parks, and weather conditions. The simulation shows the effect of the various parameters on the path of the ball. A wind tunnel panel allows the user to use velocity and pressure probes.

Center, Nasa G.

2008-08-09