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Sample records for hysteresis curve shows

  1. perature sensitive. Both electrode pairs show approximately the same thermal hysteresis.

    E-print Network

    Mandelis, Andreas

    236 perature sensitive. Both electrode pairs show approximately the same thermal hysteresis. The E greatly improve their thermal hysteresis characteristics. thermal hysteresis,whereas the glass electrodeshows a thermd hysteresis dependent on the actual pH of the solution. It should be noted that E

  2. Dynamics of periodic anticrossings: Decoherence, pointer states and hysteresis curves

    E-print Network

    Peter Foldi; Mihaly G. Benedict; F. M. Peeters

    2008-02-05

    We consider a strongly driven two-level (spin) system, with a periodic external field that induces a sequence of avoided level crossings. The spin system interacts with a bosonic reservoir which leads to decoherence. A Markovian dynamical equation is introduced without relying on the rotating wave approximation in the system-external field interaction. We show that the time evolution of the two-level system is directed towards an incoherent sum of periodic Floquet states regardless of the initial state and even the type of the coupling to the environment. Analyzing the time scale of approaching these time-dependent pointer states, information can be deduced concerning the nature and strength of the system-environment coupling. The inversion as a function of the external field is usually multi-valued, and the form of these hysteresis curves is qualitatively different for low and high temperatures. For moderate temperatures we found that the series of Landau-Zener-St\\"{u}ckelberg-type transitions still can be used for state preparation, regardless of the decoherence rate. Possible applications include quantum information processing and molecular nanomagnets.

  3. Hysteresis and uncertainty in soil water-retention curve parameters

    USGS Publications Warehouse

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

    2014-01-01

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

  4. Hysteresis Phenomenon in Heat-Voltage Curves of Polypyrrole-Coated Electrospun Nanofibrous and Regular Fibrous Mats

    NASA Astrophysics Data System (ADS)

    Oroumei, Azam; Tavanai, Hossein; Morshed, Mohammad

    2015-07-01

    This article verifies the hysteresis phenomenon in heat-voltage curves of polypyrrole-coated electrospun nanofibrous and regular fibrous mats. A third-order polynomial model fits the heat-voltage data better than a second-order polynomial model. It was also observed that the hysteresis loop area of nanofibrous and regular fibrous mats increases with decreasing fiber diameter. Moreover, the curvature of the hysteresis loops is significantly affected by the fiber diameter. In fact, the slope of the curvatures increases with decreasing fiber diameter.

  5. Control over hysteresis curves and thresholds of optical bistability in different semiconductor double quantum wells

    NASA Astrophysics Data System (ADS)

    H, R. Hamedi; M, R. Mehmannavaz; Hadi, Afshari

    2015-08-01

    The effects of optical field on the phenomenon of optical bistability (OB) are investigated in a K-type semiconductor double quantum well (SDQW) under various parametric conditions. It is shown that the OB threshold can be manipulated by increasing the intensity of coupling field. The dependence of the shift of OB hysteresis curve on probe wavelength detuning is then explored. In order to demonstrate controllability of the OB in this SDQW, we compare the OB features of three different configurations which could arise in this SDQW scheme, i.e., K-type, Y-type, and inverted Y-type systems. The controllability of this semiconductor nanostructure medium makes the presented OB scheme more valuable for applications in all-optical switches, information storage, and logic circuits of all optical information processing. Project supported by the Lithuanian Research Council (Grant No. VP1-3.1-ŠM-01-V-03-001).

  6. View to southwest along bridge alignment, showing reverse curve; photographer ...

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

    View to southwest along bridge alignment, showing reverse curve; photographer unknown; 1933 photo from collection of Office-of Structures Maintenance, California Department of Transportation, Sacramento - Carroll Overhead Bridge, Altamont Pass Road, Livermore, Alameda County, CA

  7. Interior detail, building 810, view to north showing curved chord ...

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

    Interior detail, building 810, view to north showing curved chord sections of roof trusses, 90mm lens plus electronic flash fill lighting. - Travis Air Force Base, B-36 Hangar, Between Woodskill Avenue & Ellis, adjacent to Taxiway V & W, Fairfield, Solano County, CA

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

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

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

  9. 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

  10. Kinetic effects on double hysteresis in spin crossover molecular magnets analyzed with first order reversal curve diagram technique

    SciTech Connect

    Stan, Raluca-Maria; Gaina, Roxana; Enachescu, Cristian E-mail: radu.tanasa@uaic.ro; Stancu, Alexandru; Tanasa, Radu E-mail: radu.tanasa@uaic.ro; Bronisz, Robert

    2015-05-07

    In this paper, we analyze two types of hysteresis in spin crossover molecular magnets compounds in the framework of the First Order Reversal Curve (FORC) method. The switching between the two stable states in these compounds is accompanied by hysteresis phenomena if the intermolecular interactions are higher than a threshold. We have measured the static thermal hysteresis (TH) and the kinetic light induced thermal hysteresis (LITH) major loops and FORCs for the polycrystalline Fe(II) spin crossover compound [Fe{sub 1?x}Zn{sub x}(bbtr){sub 3}](ClO{sub 4}){sub 2} (bbtr?=?1,4-di(1,2,3-triazol-1-yl)butane), either in a pure state (x?=?0) or doped with Zn ions (x?=?0.33) considering different sweeping rates. Here, we use this method not only to infer the domains distribution but also to disentangle between kinetic and static components of the LITH and to estimate the changes in the intermolecular interactions introduced by dopants. We also determined the qualitative relationship between FORC distributions measured for TH and LITH.

  11. Crossing in the magnetic force-gap hysteresis curve of magnetic levitation systems with a high- T c superconductor

    NASA Astrophysics Data System (ADS)

    Gou, Xiao-Fan; Zhang, Zhao-Xia

    2010-05-01

    For the magnetic levitation system consisting of a high- T c superconductor and permanent magnet, the relation curve of magnetic force with gap between these two components is known as a hysteresis loop, that is, the approaching and departing portions envelop a complete one, and generally these two portions do not cross each other. However, in some special cases this crossing arises, and makes the complete loop broken. In this paper, by the numerical simulation of the magnetic force-gap curve in large numbers of physical and geometrical parameters, two typical crossings were found. To investigate the crossing and explore its physical causes, for one of the crossings, the current density in the superconductor was further calculated and its magnitude and vector distribution at the gaps nearby where the crossing arises were obtained. Based on these calculation results and an adequate discussion, the conclusion was induced that the crossing in the magnetic force-gap hysteresis curve results from applied magnetic field’s incomplete and insufficient penetrating in superconductor.

  12. Describing the effect of tempering on hysteresis curves of 54SiCr6 spring steel by the effective field model

    NASA Astrophysics Data System (ADS)

    Perevertov, O.

    2012-04-01

    Hysteresis loops of a ferromagnetic material containing internal stresses due to heat treatment are investigated. The 54SiCr6 spring steel was quenched and tempered in the 300-740 °C range. At temperatures from 300 to 500 °C changes in hysteresis curves can be described with a very good accuracy by the effective field model found previously for steels under stress due to direct mechanical loading. The effective field due to tempering had a similar shape with that by direct application of external compressive stress. In the range 300-500 °C the effective field changes linearly with the tempering temperature. These magnetic results are in correspondence with other works showing that in this temperature range the internal stress decreases by more than two orders of magnitude. At temperatures above 500 °C the change of magnetic properties is not monotonous because of influence of different factors-the spheroidization and the coarsening of the cementite, followed by recovery and recrystallization above 600 °C.

  13. Zero-dipole molecular organic cations in mixed organic-inorganic halide perovskites: possible chemical solution for the reported anomalous hysteresis in the current-voltage curve measurements.

    PubMed

    Giorgi, Giacomo; Yamashita, Koichi

    2015-11-01

    Starting from a brief description of the main architectures characterizing the novel solar technology of perovskite-based solar cells, we focus our attention on the anomalous hysteresis experimentally found to affect the measurement of the current-voltage curve of such devices. This detrimental effect, associated with slow dynamic reorganization processes, depends on several parameters; among them, the scan rate of the measurements, the architecture of the cell, and the perovskite deposition rate are crucial. Even if a conclusive explanation of the origin of the hysteresis has not been provided so far, several experimental findings ascribe its origin to ionic migration at an applied bias and dielectric polarization that occurs in the perovskite layer. Consistently, a dipole-moment-reduced cation such as formamidinium ion is experimentally reported to quantitatively reduce the hysteresis from perovskite-based devices. By means of a density-functional theory-based set of calculations, we have predicted and characterized guanidinium ion (GA = (+)[C(NH2)3], a zero-dipole moment cation by symmetry)-based organic-inorganic halide perovskite's structural and electronic properties, speculating that such a cation and the alloys it may form with other organic cations can represent a possible chemical solution for the puzzling issue of the hysteresis. PMID:26468971

  14. Zero-dipole molecular organic cations in mixed organic-inorganic halide perovskites: possible chemical solution for the reported anomalous hysteresis in the current-voltage curve measurements

    NASA Astrophysics Data System (ADS)

    Giorgi, Giacomo; Yamashita, Koichi

    2015-11-01

    Starting from a brief description of the main architectures characterizing the novel solar technology of perovskite-based solar cells, we focus our attention on the anomalous hysteresis experimentally found to affect the measurement of the current-voltage curve of such devices. This detrimental effect, associated with slow dynamic reorganization processes, depends on several parameters; among them, the scan rate of the measurements, the architecture of the cell, and the perovskite deposition rate are crucial. Even if a conclusive explanation of the origin of the hysteresis has not been provided so far, several experimental findings ascribe its origin to ionic migration at an applied bias and dielectric polarization that occurs in the perovskite layer. Consistently, a dipole-moment-reduced cation such as formamidinium ion is experimentally reported to quantitatively reduce the hysteresis from perovskite-based devices. By means of a density-functional theory-based set of calculations, we have predicted and characterized guanidinium ion (GA = +[C(NH2)3], a zero-dipole moment cation by symmetry)-based organic-inorganic halide perovskite’s structural and electronic properties, speculating that such a cation and the alloys it may form with other organic cations can represent a possible chemical solution for the puzzling issue of the hysteresis.

  15. Hysteresis in single and polycrystalline iron thin films: Major and minor loops, first order reversal curves, and Preisach modeling

    NASA Astrophysics Data System (ADS)

    Cao, Yue; Xu, Ke; Jiang, Weilin; Droubay, Timothy; Ramuhalli, Pradeep; Edwards, Danny; Johnson, Bradley R.; McCloy, John

    2015-12-01

    Hysteretic behavior was studied in a series of Fe thin films, grown by molecular beam epitaxy, having different grain sizes and grown on different substrates. Major and minor loops and first order reversal curves (FORCs) were collected to investigate magnetization mechanisms and domain behavior under different magnetic histories. The minor loop coefficient and major loop coercivity increase with decreasing grain size due to higher defect concentration resisting domain wall movement. First order reversal curves allowed estimation of the contribution of irreversible and reversible susceptibilities and switching field distribution. The differences in shape of the major loops and first order reversal curves are described using a classical Preisach model with distributions of hysterons of different switching fields, providing a powerful visualization tool to help understand the magnetization switching behavior of Fe films as manifested in various experimental magnetization measurements.

  16. Analysis of First Order Reversal Curves in the Thermal Hysteresis of Spin-crossover Nanoparticles within the Mechanoelastic Model

    E-print Network

    Stoleriu, Laurentiu; Chakraborty, Pradip; Hauser, Andreas; Enachescu, Cristian

    2015-01-01

    The recently obtained spin-crossover nanoparticles are possible candidates for applications in the recording media industry as materials for data storage, or as pressure and temperature sensors. For these applications the intermolecular interactions and interactions between spin-crossover nanoparticles are extremely important, as they may be essential factors in triggering the transition between the two stable phases: the high-spin and low-spin ones. In order to find correlations between the distributions in size and interactions and the transition temperatures distribution, we apply the FORC (First Order Reversal Curves) method, using simulations based on a mechanoelastic model applied to 2D triangular lattices composed of molecules linked by springs and embedded in a surfactant. We consider two Gaussian distributions: one of the size of the nanoparticles and one of the elastic interactions between edge spin-crossover molecules and the surfactant molecules. In order to disentangle the kinetic and non-kinetic...

  17. Abstract: Present ferroelectric (FE) capacitor models mostly rely on continuous hysteresis loop characteristics of FE materials. Our experimental results show that this approach overestimates

    E-print Network

    Gulak, P. Glenn

    Abstract: Present ferroelectric (FE) capacitor models mostly rely on continuous hysteresis loop-model. The model mainly consists of two nonlinear capacitors, corresponding to the two different polarization states of an FE capacitor. I. INTRODUCTION Ferroelectric (FE) capacitors have long been recognized

  18. Abstract: Present ferroelectric (FE) capacitor models mostly rely on continuous hysteresis loop characteristics of FE materials. Our experimental results show that this approach overestimates

    E-print Network

    Sheikholeslami, Ali

    Abstract: Present ferroelectric (FE) capacitor models mostly rely on continuous hysteresis loop­model. The model mainly consists of two nonlinear capacitors, corresponding to the two different polarization states of an FE capacitor. I. INTRODUCTION Ferroelectric (FE) capacitors have long been recognized

  19. Experimental Study on Interlayer Magnetic Coupling in Sputtered Al/Fe/Al/Gd Magnetic Multilayer Films: II. Hysteresis Curves of X-ray Magnetic Circular Dicroism at the Gd-L3 Edge

    NASA Astrophysics Data System (ADS)

    Nobuhiko Sakai,; Ritthikrai Chai-Ngam,; Akihisa Koizumi,; Hisao Kobayashi,

    2010-06-01

    The spacer thickness dependence of the interlayer magnetic coupling (IMC) between Gd and Fe layers separated by Al spacers has been studied. Magnetization measurement and X-ray magnetic circular dicroism (XMCD) spectroscopy at the Gd-L3 edge have been carried out on sputtered Fe (20 Å)/Al (R Å)/Gd (40 Å) multilayer films (MLFs) for R = 0, 5, 10, and 100 and on some reference films. Experimental data at low magnetic fields below 1 kOe are carefully investigated. A simple theoretical model is introduced to evaluate the strength of IMC. The energy of IMC is represented by the term J MFe \\cdot MGd, in which MFe and MGd denote the average overall magnetic moments of Fe and Gd layers, respectively. It is found that J, which is evaluated from the magnetization curves and the Gd-XMCD signals, is 370 × 104 Oe\\cdotcm2/emu for MLF of R = 0, and can be reduced by one order of magnitude when R is changed from 0 to 10. Most of characteristic features of the experimental data are ascribed to the varing magnetization of Gd layers. It is found that 40 Å Gd layers, which are paramagnetic at 5 K when isolated using 100 Å Al spacers, show magnetic hysteresis when sandwiched between Fe layers.

  20. A magnetic hysteresis model

    NASA Technical Reports Server (NTRS)

    Flatley, Thomas W.; Henretty, Debra A.

    1995-01-01

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

  1. Plant Photosynthesis-Irradiance Curve Responses to Pollution Show Non-Competitive Inhibited Michaelis Kinetics

    PubMed Central

    Lin, Maozi; Wang, Zhiwei; He, Lingchao; Xu, Kang; Cheng, Dongliang; Wang, Genxuan

    2015-01-01

    Photosynthesis-irradiance (PI) curves are extensively used in field and laboratory research to evaluate the photon-use efficiency of plants. However, most existing models for PI curves focus on the relationship between the photosynthetic rate (Pn) and photosynthetically active radiation (PAR), and do not take account of the influence of environmental factors on the curve. In the present study, we used a new non-competitive inhibited Michaelis-Menten model (NIMM) to predict the co-variation of Pn, PAR, and the relative pollution index (I). We then evaluated the model with published data and our own experimental data. The results indicate that the Pn of plants decreased with increasing I in the environment and, as predicted, were all fitted well by the NIMM model. Therefore, our model provides a robust basis to evaluate and understand the influence of environmental pollution on plant photosynthesis. PMID:26561863

  2. A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space

    E-print Network

    Zhou, Quanlin

    A modeling approach to represent hysteresis in capillary pressure- saturation relationship based of hysteresis behavior and capillary entrapment of wetting and nonwetting fluids. The hysteretic constitutive measurements of primary drainage and main wetting curves. The hysteresis model results are verified

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

    SciTech Connect

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

    2004-03-12

    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.

  4. Hysteresis in the Sky

    E-print Network

    Sayantan Choudhury; Shreya Banerjee

    2015-06-11

    Hysteresis is a phenomenon occurring naturally in several magnetic and electric materials in condensed matter physics. When applied to cosmology, aka cosmological hysteresis, has interesting and vivid implications in the scenario of a cyclic bouncy universe. Most importantly, this physical prescription can be treated as an alternative proposal to inflationary paradigm. Cosmological hysteresis is caused by the asymmetry in the equation of state parameter during expansion and contraction phase of the universe, due to the presence of a single scalar field. This process is purely thermodynamical in nature, results in a non-vanishing hysteresis loop integral $(\\oint pdV)$ in cosmology. When applied to variants of modified gravity models -1) Dvali-Gabadadze-Porrati (DGP) brane world gravity, 2) Cosmological constant dominated Einstein gravity, 3) Loop Quantum Gravity (LQG), 4) Einstien-Gauss-Bonnet brane world gravity and 5) Randall Sundrum single brane world gravity (RSII), under certain circumstances, this phenomenon leads to the increase in amplitude of the consecutive cycles and to a universe with older and larger successive cycles, provided we have physical mechanisms to make the universe bounce and turnaround. This inculcates an arrow of time in a dissipationless cosmology. Remarkably, this phenomenon appears to be widespread in several cosmological potentials in variants of modified gravity background, which we explicitly study for- i) Hilltop, ii) Natural and iii) Colemann-Weinberg potentials, in this paper. Semi-analytical analysis of these models, for different potentials with minimum/minima, show that the conditions which creates a universe with an ever increasing expansion, depend on the signature of the hysteresis loop integral $(\\oint pdV)$ as well as on the variants of model parameters.

  5. The magnetization process: Hysteresis

    NASA Technical Reports Server (NTRS)

    Balsamel, Richard

    1990-01-01

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

  6. Reversal-field memory in the hysteresis of spin glasses.

    PubMed

    Katzgraber, H G; Pázmándi, F; Pike, C R; Liu, Kai; Scalettar, R T; Verosub, K L; Zimányi, G T

    2002-12-16

    We report a novel singularity in the hysteresis of spin glasses, the reversal-field memory effect, which creates a nonanalyticity in the magnetization curves at a particular point related to the history of the sample. The origin of the effect is due to the existence of a macroscopic number of "symmetric clusters" of spins associated with a local spin-reversal symmetry of the Hamiltonian. We use first order reversal curve (FORC) diagrams to characterize the effect and compare to experimental results on thin magnetic films. We contrast our results on spin glasses to random magnets and show that the FORC technique is an effective "magnetic fingerprinting" tool. PMID:12484912

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

    PubMed Central

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

    2014-01-01

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

  8. Design of experiment for hysteresis loops measurement

    NASA Astrophysics Data System (ADS)

    Tu?ková, Michaela; Harman, Radoslav; Tu?ek, Pavel; Tu?ek, Ji?í

    2014-11-01

    Hysteresis loop measurements are frequently used to assess the magnetic quality of a nanomaterial under an external magnetic field. Based on the values of the hysteresis parameters, it is possible to decide whether the nanomaterial meets requirements of a given application. In this work, we present a new approach to the measurement of the hysteresis loop based on the theory of optimal experimental design. We show that the maximin efficient design leads to a reduction in the measurements costs when compared to the standard equispaced measurement design. Moreover, a significantly higher accuracy in the estimation of hysteresis parameters is reached within a broad range of plausible values. The functionality of the proposed approach is successfully tested considering real experimental data obtained from the hysteresis loop measurements of the ?-Fe2O3 phase. The measurement procedure can be easily adapted to any magnetic nanomaterial for which the values of its hysteresis parameters are to be determined.

  9. Hysteresis compensation of piezoelectric actuators: the modified Rayleigh model.

    PubMed

    Park, Jongkyu; Moon, Wonkyu

    2010-03-01

    In this study, we develop a novel modified Rayleigh model for hysteresis compensation in piezoelectric actuators. Piezoelectric actuators suffer from hysteresis, in large drive fields of more than 100 V, which can result in serious displacement errors. The typical phenomenological approach is to use the Rayleigh model; however, this model gives more than 10% difference with experiments at the large electric fields of more than 1kV/mm. Furthermore, there are no studies that apply the Rayleigh model to the compensation of precision actuators, such as stack actuators; it has only been applied in the study of the physical properties of piezoelectric materials. Therefore, we propose a modified Rayleigh model, in which each coefficient is defined differently according to whether the field is increasing or decreasing to account for asymmetry at the high fields. By applying a computer-based control from an inverse form of this modified Rayleigh model, we show that we can compensate for hysteresis to reduce the position error to less than five percent. This model has the merits of reducing complicated fitting procedures and of saving computation time compared to the Preisach model. Specifically, this model cannot only predict the hysteresis curves in all local fields using only one fitting procedure, but also make it possible to control the displacement of various piezo-based actuators without expensive sensors, based on the charge-based model. PMID:19939427

  10. A simple model of hysteresis behavior using spreadsheet analysis

    NASA Astrophysics Data System (ADS)

    Ehrmann, A.; Blachowicz, T.

    2015-01-01

    Hysteresis loops occur in many scientific and technical problems, especially as field dependent magnetization of ferromagnetic materials, but also as stress-strain-curves of materials measured by tensile tests including thermal effects, liquid-solid phase transitions, in cell biology or economics. While several mathematical models exist which aim to calculate hysteresis energies and other parameters, here we offer a simple model for a general hysteretic system, showing different hysteresis loops depending on the defined parameters. The calculation which is based on basic spreadsheet analysis plus an easy macro code can be used by students to understand how these systems work and how the parameters influence the reactions of the system on an external field. Importantly, in the step-by-step mode, each change of the system state, compared to the last step, becomes visible. The simple program can be developed further by several changes and additions, enabling the building of a tool which is capable of answering real physical questions in the broad field of magnetism as well as in other scientific areas, in which similar hysteresis loops occur.

  11. Modified Maxwell Model for hysteresis compensation of piezoelectric stack actuators

    E-print Network

    Xie, Xiaoyue, S.B. Massachusetts Institute of Technology

    2015-01-01

    This thesis presents new observations of the hysteresis behavior of piezoelectric stack actuators and proposes an Input-Range Dependent Maxwell Model for more accurate hysteresis compensation. Experimental studies show ...

  12. ORIGINAL ARTICLE The impacts of hysteresis on variably saturated hydrologic

    E-print Network

    Borja, Ronaldo I.

    cannot be considered in the hydrologic simulation, the wetting soil­water retention curve, which retention curves indicate that using either the drying soil­water retention curve or an intermediate soil- sidering hysteresis or using the wetting soil­water retention curve, the potential for landsliding

  13. Theory of molecular hysteresis switch

    NASA Astrophysics Data System (ADS)

    Kozhushner, Mortko; Oleynik, Ivan

    2006-03-01

    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).

  14. Extending hysteresis operators to spaces of piecewise continuous functions

    E-print Network

    Bath, University of

    Extending hysteresis operators to spaces of piecewise continuous functions #3; H. LOGEMANN and A@maths.bath.ac.uk, am@maths.bath.ac.uk Abstract: We consider continuous-time hysteresis operators, de#12;ned show how a hysteresis operator de#12;ned on the space of continuous piece- wise monotone functions, can

  15. Efficient Computational Model of Hysteresis

    NASA Technical Reports Server (NTRS)

    Shields, Joel

    2005-01-01

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

  16. Hysteresis in Metal Hydrides.

    ERIC Educational Resources Information Center

    Flanagan, Ted B., And Others

    1987-01-01

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

  17. Entropic dynamical hysteresis in a driven system

    NASA Astrophysics Data System (ADS)

    Mondal, Debasish; Das, Moupriya; Ray, Deb Shankar

    2012-03-01

    We show that the application of a time periodic field driving a Brownian particle between the two lobes of a two-dimensional bilobal enclosure results in a hysteresis loop in the variation of integrated probability of residence of the particle as a function of the field. The confinement of the particle is characterized by symmetry breaking of the hysteresis loop, and the area of the loop exhibits a turnover with variation of frequency of the field. This dynamical hysteresis is geometry controlled, entropic in nature, and amenable to theoretical analysis with a two-state model.

  18. Corneal hysteresis and its relevance to glaucoma

    PubMed Central

    Deol, Madhvi; Taylor, David A.; Radcliffe, Nathan M.

    2015-01-01

    Purpose of review Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Recent findings Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. Summary It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness. PMID:25611166

  19. Adhesion hysteresis of silane coated microcantilevers

    SciTech Connect

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

    2000-04-17

    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.

  20. Hysteresis effects in Bose-Einstein condensates

    SciTech Connect

    Sacchetti, Andrea

    2010-07-15

    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.

  1. Hysteresis effects in Bose-Einstein condensates

    E-print Network

    Andrea Sacchetti

    2010-06-16

    Here, we consider damped two-components 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 between the appearance of saddle node bifurcations and damping effect.

  2. Hysteresis in the Sky

    E-print Network

    Choudhury, Sayantan

    2015-01-01

    Hysteresis is a phenomenon occurring naturally in several magnetic and electric materials in condensed matter physics. When applied to cosmology, aka cosmological hysteresis, has interesting and vivid implications in the scenario of a cyclic bouncy universe. Most importantly, this physical prescription can be treated as an alternative proposal to inflationary paradigm. Cosmological hysteresis is caused by the asymmetry in the equation of state parameter during expansion and contraction phase of the universe, due to the presence of a single scalar field. This process is purely thermodynamical in nature, results in a non-vanishing hysteresis loop integral $(\\oint pdV)$ in cosmology. When applied to variants of modified gravity models -1) Dvali-Gabadadze-Porrati (DGP) brane world gravity, 2) Cosmological constant dominated Einstein gravity, 3) Loop Quantum Gravity (LQG), 4) Einstien-Gauss-Bonnet brane world gravity and 5) Randall Sundrum single brane world gravity (RSII), under certain circumstances, this phenom...

  3. Random Hysteresis Loops

    E-print Network

    Gioia Carinci

    2013-12-01

    Dynamical hysteresis is a phenomenon which arises in ferromagnetic systems below the critical temperature as a response to adiabatic variations of the external magnetic field. We study the problem in the context of the mean-field Ising model with Glauber dynamics, proving that for frequencies of the magnetic field oscillations of order $N^{2/3}$, with $N$ the size of the system, the "critical" hysteresis loop becomes random.

  4. Transport, hysteresis and avalanches in artificial spin ice systems

    SciTech Connect

    Reichhardt, Charles; Reichhardt, Cynthia J; Libal, A

    2010-01-01

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

  5. Mesoscopic magnetomechanical hysteresis in a magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

    Biller, A. M.; Stolbov, O. V.; Raikher, Yu. L.

    2015-08-01

    Field-induced magnetostatic interaction in a pair of identical particles made of a magnetically soft ferromagnet is studied. It is shown that due to saturation of the ferromagnet magnetization, this case differs significantly from the (super)paramagnetic one. A numerical solution is given, discussed, and compared with that provided by a simpler model (nonlinear mutual dipoles). We show that for multidomain ferromagnetic particles embedded in an elastomer matrix, as for paramagnetic ones in the same environment, pair clusters may form or break by a hysteresis scenario. However, the magnetization saturation brings in important features to this effect. First, the bistability state and the hysteresis take place only in a limited region of the material parameters of the system. Second, along with the hysteresis jumps occurring under the sole influence of the field, the "latent" hysteresis is possible which realizes only if the action of the field is combined with some additional (nonmagnetic) external factor. The obtained conditions, when used to assess the possibility of clustering in real magnetorheological polymers, infer an important role of mesoscopic magnetomechanical hysteresis for the macroscopic properties of these composites.

  6. Triangular Current: Method for Measuring Hysteresis Loops of Ferroelectric Capacitors

    NASA Astrophysics Data System (ADS)

    Wang, Ding-Yeong; Chang, Chun-Yen

    2004-09-01

    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.

  7. Predictability of magnetic hysteresis and thermoremanent magnetization using Preisach theory

    NASA Astrophysics Data System (ADS)

    Newell, A. J.; Niemerg, M.; Bates, D.

    2014-12-01

    Preisach theory is a phenomenological model of hysteresis that is the basis for FORC analysis in rock magnetism. In FORC analysis, a system is characterized using first-order reversal curves (FORCs), each of which is a magnetization curve after a reversal in the direction of change of the magnetic field. Preisach theory uses the same curves to predict the magnetic response to changes in the magnetic field. In rock magnetism, the Preisach model has been adapted to predict general properties of thermoremanent magnetization (TRM), and even to inferpaleointensity from room-temperature FORCs. Preisach theory represents hysteresis by a collection of hysteresis units called hysterons; the distribution of hysterons is inferred from FORC measurements. Each hysteron represents a two-state system. This is similar to a single-domain (SD) magnet, but the first-order theory cannot represent the magnetism of a simple system of randomly oriented SD magnets. Such a system can be represented by a second-order Preisach theory, which requires the measurement of magnetization curves after two reversals of the direction of change. One can generalize this process to higher order reversal curves, although each increase in the number of reversals greatly increases the number of measurements that are needed. The magnetic hysteresis of systems of interacting SD magnets is calculated using numerical homotopy, a method that can find all the solutions of the equilibrium equations for such a system. The hysteresis frequently has features that cannot be represented by any order of Preisach theory. Furthermore, there are stable magnetic states that are not reachable during isothermal hysteresis unless thermal fluctuations are large enough. Such states would not be visible at room temperature but would contribute to TRM.

  8. Positive hysteresis of Ce-doped GAGG scintillator

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Koshimizu, Masanori; Watanabe, Kenichi; Sato, Hiroki; Yagi, Hideki; Yanagitani, Takagimi

    2014-10-01

    Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd3(Al, Ga)5O12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60Co ?-rays, Ce 1% doped GAGG crystal exhibited ?20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm.

  9. Precise Tracking Control of a Piezoactuated Micropositioning Stage Based on Modified Prandtl-Ishlinskii Hysteresis Model

    E-print Network

    Li, Yangmin

    -Ishlinskii Hysteresis Model Qingsong Xu, Member, IEEE, and Yangmin Li, Senior Member, IEEE Abstract-- In this paper, the hysteresis modeling and com- pensation are carried out and verified for a piezo-driven XY parallel. Results show that the combined control scheme can reduce the nonsymmetric hysteresis to a negligible level

  10. Capillary Condensation Hysteresis in Overlapping Spherical Pores: A Monte Carlo Simulation Study

    E-print Network

    Muzzio, Fernando J.

    Capillary Condensation Hysteresis in Overlapping Spherical Pores: A Monte Carlo Simulation Study crystals. We show different mechanisms of capillary hysteresis depending on the size of the window between the pores. For the system with a small window, the hysteresis cycle is similar to that in a single spherical

  11. Assessment of the hydrological behaviour of watersheds of contrasting land use using suspended sediment-discharge hysteresis patterns

    NASA Astrophysics Data System (ADS)

    Giménez, Rafael; Casalí, Javier; Díez, Javier; Goñi, Mikel; Campo, Miguel A.

    2010-05-01

    Four experimental watersheds in Navarre (Spain), maintained by the local government, have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz "principal", Op, and Oskotz "woodland", Ow). La Tejería and Latxaga watersheds, located in the central western part of Navarre, are roughly similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (alkaline, fine texture topsoil), climate (humid sub Mediterranean) and land use (80-90% cultivated with winter grain crops). On the other hand, Op (ca.1,700 ha) is covered with forest and pasture (cattle-breeding); while Ow (ca. 500 ha), a sub-watershed of the Op, is almost completely covered with forest. The predominant climate in Op/Ow is sub-Atlantic. As a result, a detailed description and a general characterization of the hydrological and erosion behaviour of these watersheds were published recently by the same authors of this current research. However, this information, although extensive and valuable, is still insufficient for finding out the internal and complex hydrological functioning of these watersheds reflected in the frequent occurrence of the hysteresis phenomenon. "Hysteresis" is when the amount of sediment concentration associated with a certain flow is different depending on the direction in which the analysis is performed -towards the increase or towards the diminution of the flow. This phenomenon to some extent reflects the way in which the runoff generation processes are conjugated with those of the production and transport of sediments, hence the usefulness of hysteresis as a diagnostic hydrological parameter. However, the complexity of the phenomena and factors which determine hysteresis make its interpretation uncertain or, at the very least, problematic. 5 types of hysteresis have been recognized but, however, only three types are usually reported: "clockwise", "anticlockwise" and "eight-shape". This article aims to investigate the hydrological-erosion behaviour of 4 watersheds with contrasting land uses by means of the analysis and interpretation of the sediment-flow relationship throughout a long period of time. The first results of this work are presented here. The sediment-flow relationship of 375 events occurring between 1996 and 2009 in the La Tejería, Latxaga, Ow and Op watersheds was analyzed seeking to identify events presenting hysteresis. To make the comparison between events easier a normalized hysteresis index was calculated -although it was only applicable for clockwise and anticlockwise hysteresis- based on the determination of the area comprised between the top and bottom limbs of the sediment-flow graph. Only 25-60% of the events taking place in the grain-cultivated watersheds exhibited a clear hysteresis. Conversely, in Op/Ow this figure rose to 95%. In the watersheds cultivated with grain, the factors controlling erosion -protection due to cultivation, tillage, etc.- can change drastically throughout the year and even inside one same watershed, so that it is not surprising that the sediment-flow relationship did not show a clear hysteresis, unlike what happened in the watersheds under woodland/pasture. In general, 3 types of hysteresis were observed: clockwise, anticlockwise and eight-shape, although the first of these was predominant. It was, thus, in Op/Ow that 90% of the events which displayed hysteresis did so with the clockwise type, whereas in La Tejería this rate was only 50%. Also, the hysteresis in Op/Ow and Laxtaga was more clearly defined (a higher index) than that in La Tejería. This predominance of curves with clockwise hysteresis suggest that the main areas of sediment discharge were to be found in the banks and areas near to the bed and to the record station.

  12. Dynamic hysteresis features in a two-dimensional mixed Ising system

    NASA Astrophysics Data System (ADS)

    Erta?, Mehmet; Keskin, Mustafa

    2015-08-01

    The dynamic hysteresis features in a two-dimensional mixed spin (1 , 3 / 2) Ising system are studied by using the within the effective-field theory with correlations based on Glauber-type stochastic. The dynamic phase transition temperatures and dynamic hysteresis curves are obtained for both the ferromagnetic and antiferromagnetic interactions. It is observed that the dynamic hysteresis loop areas increase when the reduced temperatures increase, and the dynamic hysteresis loops disappear at certain reduced temperatures. The thermal behaviors of the coercivity and remanent magnetizations are also investigated. The results are compared with some theoretical and experimental works and found in a qualitatively good agreement.

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

    NASA Astrophysics Data System (ADS)

    Dunlop, D. J.

    2008-12-01

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

  14. The significance of observed rotational magnetic hysteresis in lunar samples

    NASA Technical Reports Server (NTRS)

    Wasilewski, P.

    1974-01-01

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

  15. Hysteresis Parameter Identification with Limited Experimental Data

    E-print Network

    Iyer, Ram Venkataraman

    1 Hysteresis Parameter Identification with Limited Experimental Data Ram V. Iyer and Matthew E-- The Preisach operator and its variants have been successfully used in the modeling of hysteresis observed-- Hysteresis, Preisach Operator, Density function Identification, Constrained least squares, Electro

  16. Macroscopic theory for capillary-pressure hysteresis.

    PubMed

    Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry

    2015-03-01

    In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials. PMID:25646688

  17. Hysteresis and coercivity of hematite

    NASA Astrophysics Data System (ADS)

    Ã-zdemir, Ã.-zden; Dunlop, David J.

    2014-04-01

    room-temperature hysteresis, 14 submicron hematites (0.12-0.45 µm) had large coercive forces Hc (150-350 mT), while 22 natural 1-5.5 mm hematite crystals had Hc = 0.8-23 mT (basal-plane measurements). Single-domain (SD) and multidomain (MD) hematites owe their high Hc mainly to magnetoelastic anisotropy, caused in fine particles by internal strains and in large crystals by defects like dislocations, with a smaller contribution by triaxial magnetocrystalline anisotropy. A strong correlation between Hc and the defect moment Md measured below hematite's Morin transition also favors magnetoelastic control. Saturation remanence/saturation magnetization ratios Mrs/Ms and coercivity ratios Hcr/Hc (Hcr is remanent coercive force) are distinctive: Mrs/Ms = 0.5-0.9, Hcr/Hc = 1.02-1.17 for MD hematites; Mrs/Ms = 0.5-0.7, Hcr/Hc = 1.45-1.62 for SD hematites. In high-temperature (20-690°C) hysteresis, Hc(T) ~ Ms(T) to a power 1.8-2.4 above 385°C. Magnetoelastic wall pinning by crystal defects is thus more likely than control by domain nucleation which depends on magnetocrystalline anisotropy. Our results compare well with existing Hc vs. crystal size d data. A suggested peak in Hc around 15 µm and a proposed slope change around 100 µm are both questionable. Using only near-saturation data, Hc varies continuously as d-0.61 from ?0.1 µm to 2 mm. The SD threshold size d0 may be >15 µm but there is no strong evidence that d0 ?100 µm. Direct domain observations are needed to settle the question. Augmented data sets for Hc and Mrs vs. d show that SD hematite is increasingly affected by thermal fluctuations below ?0.3 µm and generally confirm a superparamagnetic threshold size ds of 0.025-0.03 µm.

  18. Hysteresis of boiling for different tunnel-pore surfaces

    NASA Astrophysics Data System (ADS)

    Pastuszko, Robert; Piasecka, Magdalena

    2015-05-01

    Analysis of boiling hysteresis on structured surfaces covered with perforated foil is proposed. Hysteresis is an adverse phenomenon, preventing high heat flux systems from thermal stabilization, characterized by a boiling curve variation at an increase and decrease of heat flux density. Experimental data were discussed for three kinds of enhanced surfaces: tunnel structures (TS), narrow tunnel structures (NTS) and mini-fins covered with the copper wire net (NTS-L). The experiments were carried out with water, R-123 and FC-72 at atmospheric pressure. A detailed analysis of the measurement results identified several cases of type I, II and III for TS, NTS and NTS-L surfaces.

  19. Two-phase equilibrium states in individual Cu-Ni nanoparticles: size, depletion and hysteresis effects.

    PubMed

    Shirinyan, Aram S

    2015-01-01

    In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase transformation of binary alloyed nanoparticles taking into account size effects as well as depletion and hysteresis effects. In such a way the hysteresis in a form of nonsymmetry for forth and back transforming paths takes place; compositional splitting and the loops-like splitted path on the size dependent temperature-composition phase diagram occur. Our calculations for individual Cu-Ni nanoparticle show that one must differentiate the solubility curves and the equilibrium loops (discussed here in term of solidification and melting loops). For the first time we have calculated and present here on the temperature-composition phase diagram the nanomelting loop at the size of 80 nm and the nanosolidification loop at the size of 25 nm for an individual Cu-Ni nanoparticle. So we observe the difference between the size-dependent phase diagram and solubility diagram, between two-phase equilibrium curves and solubility curves; also intersection of nanoliquidus and nanosolidus is available. These findings lead to the necessity to reconsider such basic concepts in materials science as phase diagram and solubility diagram. PMID:26425433

  20. Two-phase equilibrium states in individual Cu–Ni nanoparticles: size, depletion and hysteresis effects

    PubMed Central

    2015-01-01

    Summary In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase transformation of binary alloyed nanoparticles taking into account size effects as well as depletion and hysteresis effects. In such a way the hysteresis in a form of nonsymmetry for forth and back transforming paths takes place; compositional splitting and the loops-like splitted path on the size dependent temperature–composition phase diagram occur. Our calculations for individual Cu–Ni nanoparticle show that one must differentiate the solubility curves and the equilibrium loops (discussed here in term of solidification and melting loops). For the first time we have calculated and present here on the temperature–composition phase diagram the nanomelting loop at the size of 80 nm and the nanosolidification loop at the size of 25 nm for an individual Cu–Ni nanoparticle. So we observe the difference between the size-dependent phase diagram and solubility diagram, between two-phase equilibrium curves and solubility curves; also intersection of nanoliquidus and nanosolidus is available. These findings lead to the necessity to reconsider such basic concepts in materials science as phase diagram and solubility diagram. PMID:26425433

  1. High contact angle hysteresis of superhydrophobic surfaces: Hydrophobic defects

    NASA Astrophysics Data System (ADS)

    Chang, Feng-Ming; Hong, Siang-Jie; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2009-08-01

    A typical superhydrophobic surface is essentially nonadhesive and exhibits very low water contact angle (CA) hysteresis, so-called Lotus effect. However, leaves of some plants such as scallion and garlic with an advancing angle exceeding 150° show very serious CA hysteresis. Although surface roughness and epicuticular wax can explain the very high advancing CA, our analysis indicates that the unusual hydrophobic defect, diallyl disulfide, is the key element responsible for contact line pinning on allium leaves. After smearing diallyl disulfide on an extended polytetrafluoroethylene (PTFE) film, which is originally absent of CA hysteresis, the surface remains superhydrophobic but becomes highly adhesive.

  2. The hysteresis limit in relaxation oscillation problems

    NASA Astrophysics Data System (ADS)

    Krejcí, P.

    2005-01-01

    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.

  3. Mach, methodology, hysteresis and economics

    NASA Astrophysics Data System (ADS)

    Cross, R.

    2008-11-01

    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.

  4. A New Model Based on Adaptation of the External Loop to Compensate the Hysteresis of Tactile Sensors.

    PubMed

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

    2015-01-01

    This paper presents a novel method to compensate for hysteresis nonlinearities observed in the response of a tactile sensor. The External Loop Adaptation Method (ELAM) performs a piecewise linear mapping of the experimentally measured external curves of the hysteresis loop to obtain all possible internal cycles. The optimal division of the input interval where the curve is approximated is provided by the error minimization algorithm. This process is carried out off line and provides parameters to compute the split point in real time. A different linear transformation is then performed at the left and right of this point and a more precise fitting is achieved. The models obtained with the ELAM method are compared with those obtained from three other approaches. The results show that the ELAM method achieves a more accurate fitting. Moreover, the involved mathematical operations are simpler and therefore easier to implement in devices such as Field Programmable Gate Array (FPGAs) for real time applications. Furthermore, the method needs to identify fewer parameters and requires no previous selection process of operators or functions. Finally, the method can be applied to other sensors or actuators with complex hysteresis loop shapes. PMID:26501279

  5. A New Model Based on Adaptation of the External Loop to Compensate the Hysteresis of Tactile Sensors

    PubMed Central

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

    2015-01-01

    This paper presents a novel method to compensate for hysteresis nonlinearities observed in the response of a tactile sensor. The External Loop Adaptation Method (ELAM) performs a piecewise linear mapping of the experimentally measured external curves of the hysteresis loop to obtain all possible internal cycles. The optimal division of the input interval where the curve is approximated is provided by the error minimization algorithm. This process is carried out off line and provides parameters to compute the split point in real time. A different linear transformation is then performed at the left and right of this point and a more precise fitting is achieved. The models obtained with the ELAM method are compared with those obtained from three other approaches. The results show that the ELAM method achieves a more accurate fitting. Moreover, the involved mathematical operations are simpler and therefore easier to implement in devices such as Field Programmable Gate Array (FPGAs) for real time applications. Furthermore, the method needs to identify fewer parameters and requires no previous selection process of operators or functions. Finally, the method can be applied to other sensors or actuators with complex hysteresis loop shapes. PMID:26501279

  6. Rotational hysteresis of exchange-spring magnets.

    SciTech Connect

    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

    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.

  7. Revisiting the hysteresis effect in surface energy budgets

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Wang, Zhi-Hua; Ni, Guang-Heng

    2013-05-01

    The hysteresis effect in diurnal cycles of net radiation Rn and ground heat flux G0 has been observed in many studies, while the governing mechanism remains vague. In this study, we link the phenomenology of hysteresis loops to the wave phase difference between the diurnal evolutions of various terms in the surface energy balance. Rn and G0 are parameterized with the incoming solar radiation and the surface temperature as two control parameters of the surface energy partitioning. The theoretical analysis shows that the vertical water flux W and the scaled ratio As*>/AT* (net shortwave radiation to outgoing longwave radiation) play crucial roles in shaping hysteresis loops of Rn and G0. Comparisons to field measurements indicate that hysteresis loops for different land covers can be well captured by the theoretical model, which is also consistent with Camuffo-Bernadi formula. This study provides insight into the surface partitioning and temporal evolution of the energy budget at the land surface.

  8. Elucidation of Conformational Hysteresis on a Giant DNA

    E-print Network

    Chwen-Yang Shew; Yuji Higuchi; Kenichi Yoshikawa

    2007-05-04

    The conformational behavior of a giant DNA mediated by condensing agents in the bulk solution has been investigated through experimental and theoretical approaches. Experimentally, a pronounced conformational hysteresis is observed for folding and unfolding processes, by increasing and decreasing the concentration of condensing agent PEG (Polyethylene glycol), respectively. To elucidate the observed hysteresis, a semiflexible chain model is studied by using Monte Carlo simulations for the coil-globule transition. In the simulations, the hysteresis loop emerges for stiff enough chains, indicating distinct pathways for folding and unfolding processes. Also, our results show that globular state is thermodynamically more stable than coiled state in the hysteresis loop. Our findings suggest that increasing chain stiffness may reduce the chain conformations relevant to the folding pathway, which impedes the folding process.

  9. Orientational hysteresis in swarms of active particles in external field

    E-print Network

    Romensky, Maksym

    2015-01-01

    Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulation of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents...

  10. An Approach to Reduction of Hysteresis in Smart Materials Juan Manuel Cruz-Hernandez and Vincent Hayward

    E-print Network

    Hayward, Vincent

    An Approach to Reduction of Hysteresis in Smart Materials Juan Manuel Cruz-Hernandez and Vincent,haywardg/Home.html Abstract This paper addresses the problem of reducing the hysteresis found in the actuation of most smart with the input. This compen- sation reduces the hysteresis to a single saturation. To show its e ectiveness

  11. Step-induced magnetic-hysteresis anisotropy in ferromagnetic thin films D. Zhao, Feng Liu,a)

    E-print Network

    Simons, Jack

    Step-induced magnetic-hysteresis anisotropy in ferromagnetic thin films D. Zhao, Feng Liu,a) D. L; accepted for publication 15 November 2001 We investigate the quasistatic magnetic hysteresis. The simulated hysteresis loops show a strong anisotropy: the coercive field is the largest when the external

  12. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 50, NO. 6, DECEMBER 2003 1165 A New Dynamic Model of Hysteresis

    E-print Network

    of Hysteresis in Harmonic Drives Rached Dhaouadi, Senior Member, IEEE, Fathi H. Ghorbel, Senior Member, IEEE the hysteresis phenomenon in harmonic drives. The ex- perimental observation of the dynamic torque-displacement rela- tionship for a harmonic drive shows a hysteresis characteristic in- dicating the simultaneous

  13. Dynamic Hysteresis in Compacted Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chowdary, Krishna M.

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

  14. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Surbhi; Tomar, Monika; Gupta, Vinay

    2015-03-01

    The influence of Cerium doping on the structural and magnetic properties of BiFeO3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi1-xCexFeO3 (BCFO) thin films with x=0-0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x?0.08. All low wavenumber Raman modes (<300 cm-1) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm-1), shows a minor shift. Sudden evolution of Raman mode at 668 cm-1, manifested as A1-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M-H) hysteresis curves with improved saturation magnetization (Ms) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi0.88Ce0.12FeO3 thin film found to exhibit better magnetic properties with Ms=15.9 emu/g without any impure phase.

  15. AVERAGING PRINCIPLE FOR DIFFERENTIAL EQUATIONS WITH HYSTERESIS

    E-print Network

    Schellekens, Michel P.

    AVERAGING PRINCIPLE FOR DIFFERENTIAL EQUATIONS WITH HYSTERESIS A. POKROVSKII O.RASSKAZOV A. VLADIMIROV Abstract. The goal of this paper is to extend the averaging technique to new classes of hysteresis on the systems with the classical Preisach nonlinearity. Key words: Averaging technique, Hysteresis, Sweeping

  16. A Homogenized Energy Framework for Ferromagnetic Hysteresis

    E-print Network

    A Homogenized Energy Framework for Ferromagnetic Hysteresis Ralph C. Smith Marcelo J. Dapino Center In this paper we develop a macroscopic framework quantifying the hysteresis and constitutive nonlinearities and full hysteresis model are validated through comparison with experimental steel and nickel data. i #12

  17. Quantum Curves

    NASA Astrophysics Data System (ADS)

    Schwarz, Albert

    2015-08-01

    One says that a pair ( P, Q) of ordinary differential operators specify a quantum curve if . If a pair of difference operators ( K, L) obey the relation KL = q LK, where , we say that they specify a discrete quantum curve. This terminology is prompted by well known results about commuting differential and difference operators, relating pairs of such operators with pairs of meromorphic functions on algebraic curves obeying some conditions. The goal of this paper is to study the moduli spaces of quantum curves. We will relate the moduli spaces for different . We will show how to quantize a pair of commuting differential or difference operators (i.e., to construct the corresponding quantum curve or discrete quantum curve).

  18. Anisotropic hysteresis on ratcheted superhydrophobic surfaces

    E-print Network

    H. Kusumaatmaja; J. M. Yeomans

    2009-04-26

    We consider the equilibrium behaviour and dynamics of liquid drops on a superhydrophobic surface patterned with sawtooth ridges or posts. Due to the anisotropic geometry of the surface patterning, the contact line can preferentially depin from one side of the ratchets, leading to a novel, partially suspended, superhydrophobic state. In both this configuration, and the collapsed state, the drops show strong directional contact angle hysteresis as they are pushed across the surface. The easy direction is, however, different for the two states. This observation allows us to interpret recent experiments describing the motion of water drops on butterfly wings.

  19. Anisotropic hysteresis on ratcheted superhydrophobic surfaces

    E-print Network

    Kusumaatmaja, H

    2009-01-01

    We consider the equilibrium behaviour and dynamics of liquid drops on a superhydrophobic surface patterned with sawtooth ridges or posts. Due to the anisotropic geometry of the surface patterning, the contact line can preferentially depin from one side of the ratchets, leading to a novel, partially suspended, superhydrophobic state. In both this configuration, and the collapsed state, the drops show strong directional contact angle hysteresis as they are pushed across the surface. The easy direction is, however, different for the two states. This observation allows us to interpret recent experiments describing the motion of water drops on butterfly wings.

  20. 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

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

    2011-02-15

    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.

  1. Hysteresis in Pressure-Driven DNA Denaturation

    PubMed Central

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

    2012-01-01

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

  2. Orientational hysteresis in swarms of active particles in external field

    NASA Astrophysics Data System (ADS)

    Romensky, M.; Lobaskin, V.

    2015-07-01

    Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulations of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and the one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents are non-universal and depend on the system's parameters, their limiting values can be predicted using a generic model of dynamic hysteresis. We also discuss similarities and differences between the swarm ordering dynamics and two-dimensional magnets.

  3. Orientational hysteresis in swarms of active particles in external field

    E-print Network

    Maksym Romensky; Vladimir Lobaskin

    2015-05-28

    Structure and ordering in swarms of active particles have much in common with condensed matter systems like magnets or liquid crystals. A number of important characteristics of such materials can be obtained via dynamic tests such as hysteresis. In this work, we show that dynamic hysteresis can be observed also in swarms of active particles and possesses similar properties to the counterparts in magnetic materials. To study the swarm dynamics, we use computer simulations of the active Brownian particle model with dissipative interactions. The swarm is confined to a narrow linear channel and the one-dimensional polar order parameter is measured. In an oscillating external field, the order parameter demonstrates dynamic hysteresis with the shape of the loop and its area varying with the amplitude and frequency of the applied field, swarm density and the noise intensity. We measure the scaling exponents for the hysteresis loop area, which can be associated with the controllability of the swarm. Although the exponents are non-universal and depend on the system's parameters, their limiting values can be predicted using a generic model of dynamic hysteresis. We also discuss similarities and differences between the swarm ordering dynamics and two-dimensional magnets.

  4. Hysteresis modeling of tunneling magnetoresistance strain sensor elements

    NASA Astrophysics Data System (ADS)

    Hauser, Hans; Rührig, Manfred; Wecker, Joachim

    2004-06-01

    Utilizing the inverse magnetostriction effect, magnetic tunneling junction (MTJ) elements have been demonstrated to also be useful as highly sensitive stress or strain transducers. The prediction of the stress dependent hysteresis of the tunneling magnetoresistance R is done by the energetic model (EM), minimizing the total magnetization work which consists of the Zeeman energy density, of magnetocrystalline and stress anisotropy of the magnetization rotation processes, and of reversible and irreversible contributions of domain wall displacements. Furthermore, the law of approach to saturation and the initial susceptibility relate the parameters of the EM to the effective anisotropy energy which has to be overcome for a magnetization reversal. The calculated R(H) curves are in good aggreement with the measurements, allowing several predictions of the MTJ parameters as magnetostriction constant, stress (strain) sensitivity and hysteresis, and misalignment of the easy axis.

  5. Hysteresis and compensation behaviors of spin-3/2 cylindrical Ising nanotube system

    SciTech Connect

    Kocakaplan, Yusuf; Keskin, Mustafa

    2014-09-07

    The hysteresis and compensation behaviors of the spin-3/2 cylindrical Ising nanotube system are studied within the framework of the effective-field theory with correlations. The effects of the Hamiltonian parameters are investigated on the magnetic and thermodynamic quantities, such as the total magnetization, hysteresis curves, and compensation behaviors of the system. Depending on the Hamiltonian parameters, some characteristic hysteresis behaviors are found, such as the existence of double and triple hysteresis loops. According to Néel classification nomenclature, the system displays Q-, R-, P-, N-, M-, and S- types of compensation behaviors for the appropriate values of the system parameters. We also compare our results with some recently published theoretical and experimental works and find a qualitatively good agreement.

  6. Completely inverted hysteresis loops: Inhomogeneity effects or experimental artifacts

    SciTech Connect

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

    2013-11-14

    Completely inverted hysteresis loops (IHL) are obtained by the superconducting quantum interference device with large cooling fields (>10 kOe) in (La,Sr)MnO{sub 3} films with self-assembled LaSrMnO{sub 4}, an antiferromagnetic interface. Although the behaviours of measured loops show many features characteristic to the IHL, its origin, however, is not due to the exchange coupling between (La,Sr)MnO{sub 3}/LaSrMnO{sub 4}, an often accepted view on IHL. Instead, we demonstrate that the negative remanence arises from the hysteresis of superconducting coils, which drops abruptly when lower cooling fields are utilized. Hence the completely inverted hysteresis loops are experimental artifacts rather than previously proposed inhomogeneity effects in complicated materials.

  7. Modelling contact angle hysteresis on chemically patterned and superhydrophobic surfaces

    E-print Network

    H. Kusumaatmaja; J. M. Yeomans

    2006-11-03

    We investigate contact angle hysteresis on chemically patterned and superhydrophobic surfaces, as the drop volume is quasi-statically increased and decreased. We consider both two, and three, dimensions using analytical and numerical approaches to minimise the free energy of the drop. In two dimensions we find, in agreement with other authors, a slip, jump, stick motion of the contact line. In three dimensions this behaviour persists, but the position and magnitude of the contact line jumps are sensitive to the details of the surface patterning. In two dimensions we identify analytically the advancing and receding contact angles on the different surfaces and we use numerical insights to argue that these provide bounds for the three dimensional cases. We present explicit simulations to show that a simple average over the disorder is not sufficient to predict the details of the contact angle hysteresis, and to support an explanation for the low contact angle hysteresis of suspended drops on superhydrophobic surfaces.

  8. Using hysteresis for optimization.

    PubMed

    Zaránd, G; Pázmándi, F; Pál, K F; Zimányi, G T

    2002-10-01

    We propose a new optimization method based on a demagnetization procedure well known in magnetism. We show how this procedure can be applied as a general tool to search for optimal solutions in any system where the configuration space is endowed with a suitable "distance." We test the new algorithm on frustrated magnetic models and the traveling salesman problem. We find that the new method successfully competes with similar basic algorithms such as simulated annealing. PMID:12365973

  9. Field-induced suppression of the ?-band superconductivity and magnetic hysteresis in the microwave surface resistance of MgB2 at temperatures near Tc

    NASA Astrophysics Data System (ADS)

    Bonura, M.; Agliolo Gallitto, A.; Li Vigni, M.; Ummarino, G. A.

    2009-05-01

    We report on the magnetic-field-induced variations of the microwave surface resistance, Rs, in a polycrystalline MgB2 sample, at different values of temperature. We have detected a magnetic hysteresis in Rs, which exhibits an unexpected plateau on decreasing the DC magnetic field below a certain value. In particular, at temperatures near Tc the hysteresis manifests itself only through the presence of the plateau. Although we do not quantitatively justify the anomalous shape of the magnetic hysteresis, we show that the results obtained in the reversible region of the Rs(H) curve can be quite well accounted for by supposing that, in this range of magnetic field, the ? gap is almost suppressed by the applied field and, consequently, all the ?-band charge carriers are quasiparticles. On this hypothesis, we have calculated Rs(H) supposing that fluxons assume a conventional (single core) structure and the flux dynamics can be described in the framework of conventional models. From the fitting of the experimental results, we determine the values of Hc2?(T) at temperatures near Tc. In our opinion, the most important result of our investigation is that, at least at temperatures near Tc, the value of the applied field that separates the reversible and irreversible regions of the Rs(H) curves is just Hc2?(T) a qualitative discussion of the possible reasons for this finding is given.

  10. Hysteresis between Distinct Modes of Turbulent Dynamos

    NASA Astrophysics Data System (ADS)

    Karak, Bidya Binay; Kitchatinov, Leonid L.; Brandenburg, Axel

    2015-04-01

    Nonlinear mean-field models of the solar dynamo show long-term variability, which may be relevant to different states of activity inferred from long-term radiocarbon data. This paper is aimed at probing the dynamo hysteresis predicted by the recent mean-field models of Kitchatinov & Olemskoy with direct numerical simulations. We perform three-dimensional (3D) simulations of large-scale dynamos in a shearing box with helically forced turbulence. As an initial condition, we either take a weak random magnetic field or we start from a snapshot of an earlier simulation. Two quasi-stable states are found to coexist in a certain range of parameters close to the onset of the large-scale dynamo. The simulations converge to one of these states depending on the initial conditions. When either the fractional helicity or the magnetic Prandtl number is increased between successive runs above the critical value for onset of the dynamo, the field strength jumps to a finite value. However, when the fractional helicity or the magnetic Prandtl number is then decreased again, the field strength stays at a similar value (strong field branch) even below the original onset. We also observe intermittent decaying phases away from the strong field branch close to the point where large-scale dynamo action is just possible. The dynamo hysteresis seen previously in mean-field models is thus reproduced by 3D simulations. Its possible relation to distinct modes of solar activity such as grand minima is discussed.

  11. Why Microtubules Run in Circles: Mechanical Hysteresis of the Tubulin Lattice

    NASA Astrophysics Data System (ADS)

    Ziebert, Falko; Mohrbach, Hervé; Kuli?, Igor M.

    2015-04-01

    The fate of every eukaryotic cell subtly relies on the exceptional mechanical properties of microtubules. Despite significant efforts, understanding their unusual mechanics remains elusive. One persistent, unresolved mystery is the formation of long-lived arcs and rings, e.g., in kinesin-driven gliding assays. To elucidate their physical origin we develop a model of the inner workings of the microtubule's lattice, based on recent experimental evidence for a conformational switch of the tubulin dimer. We show that the microtubule lattice itself coexists in discrete polymorphic states. Metastable curved states can be induced via a mechanical hysteresis involving torques and forces typical of few molecular motors acting in unison, in agreement with the observations.

  12. Why Microtubules run in Circles - Mechanical Hysteresis of the Tubulin Lattice

    E-print Network

    Ziebert, Falko; Kuli?, Igor M

    2014-01-01

    The fate of every eukaryotic cell subtly relies on the exceptional mechanical properties of microtubules. Despite significant efforts, understanding their unusual mechanics remains elusive. One persistent, unresolved mystery is the formation of long-lived arcs and rings, e.g. in kinesin-driven gliding assays. To elucidate their physical origin we develop a model of the inner workings of the microtubule's lattice, based on recent experimental evidence for a conformational switch of the tubulin dimer. We show that the microtubule lattice itself coexists in discrete polymorphic states. Curved states can be induced via a mechanical hysteresis involving torques and forces typical of few molecular motors acting in unison. This lattice switch renders microtubules not only virtually unbreakable under typical cellular forces, but moreover provides them with a tunable response integrating mechanical and chemical stimuli.

  13. Why Microtubules run in Circles - Mechanical Hysteresis of the Tubulin Lattice

    E-print Network

    Falko Ziebert; Hervé Mohrbach; Igor M. Kuli?

    2014-05-18

    The fate of every eukaryotic cell subtly relies on the exceptional mechanical properties of microtubules. Despite significant efforts, understanding their unusual mechanics remains elusive. One persistent, unresolved mystery is the formation of long-lived arcs and rings, e.g. in kinesin-driven gliding assays. To elucidate their physical origin we develop a model of the inner workings of the microtubule's lattice, based on recent experimental evidence for a conformational switch of the tubulin dimer. We show that the microtubule lattice itself coexists in discrete polymorphic states. Curved states can be induced via a mechanical hysteresis involving torques and forces typical of few molecular motors acting in unison. This lattice switch renders microtubules not only virtually unbreakable under typical cellular forces, but moreover provides them with a tunable response integrating mechanical and chemical stimuli.

  14. Semiempirical model of soil water hysteresis

    USGS Publications Warehouse

    Nimmo, J.R.

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  16. Extension of the stability of motions in a combustion chamber by non- linear active control based on hysteresis

    SciTech Connect

    Knoop, P.; Culick, F.E.C.; Zukoski, E.E.

    1996-07-01

    This report presents the first quantitative data establishing the details of hysteresis whose existence in dynamical behavior was reported by Sterling and Zukoski. The new idea was demonstrated that the presence of dynamical hysteresis provides opportunity for a novel strategy of active nonlinear control of unsteady motions in combustors. A figure shows the hysteresis exhibited for the amplitude of pressure oscillations as a function of equivalence ratio in a combustor having a recirculation zone, in this case a dump combustor.

  17. Three-Dimensionally Mesostructured Fe2O3 Electrodes with Good Rate Performance and Reduced Voltage Hysteresis

    E-print Network

    Braun, Paul

    Hysteresis Junjie Wang, Hui Zhou, Jagjit Nanda,*,,§ and Paul V. Braun*, Department of Materials Science resulted in a reduced voltage hysteresis. The electrode showed a reversible capacity of 1000 mAh g-1 at 0 capacity was about 450 mAh g-1 . The room-temperature voltage hysteresis at 0.1 A g-1 (0.1 C) was 0.62 V

  18. Stress hysteresis as the cause of persistent holes in particulate suspensions

    NASA Astrophysics Data System (ADS)

    Deegan, Robert D.

    2010-03-01

    Concentrated particulate suspensions under vibrations can support stable, localized, vertically oriented free surfaces. The most robust of these structures are persistent holes: deep and stable depressions of the interface. Using a reduced model of the hydrodynamics we show that a rheology with hysteresis can lead to motion opposite to the time-averaged applied force. Moreover, we show experimentally that particulate suspensions of cornstarch in water exhibits hysteresis in the shear-rate response to an applied sinusoidal stress. The results of our model and our experiments suggest that hysteresis accounts for the outward force needed to support persistent holes.

  19. Parameter Estimation Techniques for a Class of Nonlinear Hysteresis Models

    E-print Network

    Parameter Estimation Techniques for a Class of Nonlinear Hysteresis Models Ralph C. Smith hysteresis and constitutive nonlinearities inherent to ferroelectric, ferromagnetic and ferroelastic through comparison with experimental data. i #12;1 Introduction Hysteresis and constitutive nonlinearities

  20. Parameter Estimation Techniques for a Polarization Hysteresis Model

    E-print Network

    Parameter Estimation Techniques for a Polarization Hysteresis Model Ralph C. Smith and Andrew techniques for models quantifying hysteresis and constitutive nonlinearities in ferroelectric materials: Hysteresis model, compact operator, parameter estimation, regularization 1. Introduction Piezoceramic (PZT

  1. A Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds

    E-print Network

    A Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds Julie K. Raye- ature-dependent hysteresis and constitutive nonlinearities inherent to relaxor ferroelectric materials characterizing the de- crease in hysteresis and saturation polarization polarization as temperatures

  2. MATHEMATICAL MODELS OF HYSTERESIS (DYNAMIC PROBLEMS IN HYSTERESIS)

    SciTech Connect

    Professor Isaak Mayergoyz

    2006-08-21

    This research has further advanced the current state of the art in the areas of dynamic aspects of hysteresis and nonlinear large scale magnetization dynamics. The results of this research will find important engineering applications in the areas of magnetic data storage technology and the emerging technology of “spintronics”. Our research efforts have been focused on the following tasks: • Study of fast (pulse) precessional switching of magnetization in magnetic materials. • Analysis of critical fields and critical angles for precessional switching of magnetization. • Development of inverse problem approach to the design of magnetic field pulses for precessional switching of magnetization. • Study of magnetization dynamics induced by spin polarized current injection. • Construction of complete stability diagrams for spin polarized current induced magnetization dynamics. • Development of the averaging technique for the analysis of the slow time scale magnetization dynamics. • Study of thermal effects on magnetization dynamics by using the theory of stochastic processes on graphs.

  3. AN ENERGYBASED HYSTERESIS MODEL FOR MAGNETOSTRICTIVE TRANSDUCERS

    E-print Network

    to magnetostrictive materials must be addressed when design­ ing systems which employ them. The first concernsAN ENERGY­BASED HYSTERESIS MODEL FOR MAGNETOSTRICTIVE TRANSDUCERS F.T. Calkins Department@iastate.edu Abstract This paper addresses the modeling of hysteresis in magnetostrictive transducers

  4. Cosmological Hysteresis and the Cyclic Universe

    E-print Network

    Varun Sahni; Aleksey Toporensky

    2012-07-03

    A Universe filled with a homogeneous scalar field exhibits `Cosmological hysteresis'. Cosmological hysteresis is caused by the asymmetry in the equation of state during expansion and contraction. This asymmetry results in the formation of a hysteresis loop: $\\oint pdV$, whose value can be non-vanishing during each oscillatory cycle. For flat potentials, a negative value of the hysteresis loop leads to the increase in amplitude of consecutive cycles and to a universe with older and larger successive cycles. Such a universe appears to possess an arrow of time even though entropy production is absent and all of the equations respect time-reversal symmetry ! Cosmological hysteresis appears to be widespread and exists for a large class of scalar field potentials and mechanisms for making the universe bounce. For steep potentials, the value of the hysteresis loop can be positive as well as negative. The expansion factor in this case displays quasi-periodic behaviour in which successive cycles can be both larger as well as smaller than previous ones. This quasi-regular pattern resembles the phenomenon of BEATS displayed by acoustic systems. Remarkably, the expression relating the increase/decrease in oscillatory cycles to the quantum of hysteresis appears to be model independent. The cyclic scenario is extended to spatially anisotropic models and it is shown that the anisotropy density decreases during successive cycles if the hysteresis loop is negative.

  5. A connectivity-based modeling approach for representing hysteresis in macroscopic two-phase flow properties

    SciTech Connect

    Cihan, Abdullah; Birkholzer, Jens; Trevisan, Luca; Bianchi, Marco; Zhou, Quanlin; Illangasekare, Tissa

    2014-12-31

    During CO2 injection and storage in deep reservoirs, the injected CO2 enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO2, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO2, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role for the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm), packed with homogeneous and heterogeneous sands. Initial results show that the model can predict spatial and temporal distribution of injected fluid during the experiments reasonably well. However, further analyses are needed for comprehensively testing the ability of the model to predict transient two-phase flow processes and capillary entrapment in geological reservoirs during geological carbon sequestration.

  6. A connectivity-based modeling approach for representing hysteresis in macroscopic two-phase flow properties

    DOE PAGESBeta

    Cihan, Abdullah; Birkholzer, Jens; Trevisan, Luca; Bianchi, Marco; Zhou, Quanlin; Illangasekare, Tissa

    2014-12-31

    During CO2 injection and storage in deep reservoirs, the injected CO2 enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO2, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO2, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role formore »the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm), packed with homogeneous and heterogeneous sands. Initial results show that the model can predict spatial and temporal distribution of injected fluid during the experiments reasonably well. However, further analyses are needed for comprehensively testing the ability of the model to predict transient two-phase flow processes and capillary entrapment in geological reservoirs during geological carbon sequestration.« less

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

    SciTech Connect

    Babu, H. Aswath; Wanare, Harshawardhan

    2011-03-15

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

  8. Hysteresis of unsaturated hydromechanical properties of a silty soil

    USGS Publications Warehouse

    Lu, Ning; Kaya, Murat; Collins, Brian D.; Godt, Jonathan W.

    2013-01-01

    Laboratory tests to examine hysteresis in the hydrologic and mechanical properties of partially saturated soils were conducted on six intact specimens collected from a landslide-prone area of Alameda County, California. The results reveal that the pore-size distribution parameter remains statistically unchanged between the wetting and drying paths; however, the wetting or drying state has a pronounced influence on the water-entry pressure, the water-filled porosity at zero suction, and the saturated hydraulic conductivity. The suction stress values obtained from the shear-strength tests under both natural moisture and resaturated conditions were mostly bounded by the suction stress characteristic curves (SSCCs) obtained from the hydrologic tests. This finding experimentally confirms that the soil-water retention curve, hydraulic conductivity function, and SSCC are intrinsically related.

  9. The capillary hysteresis model HYSTR: User`s guide

    SciTech Connect

    Niemi, A.; Bodvarsson, G.S.

    1991-11-01

    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.

  10. SMA pseudo-elastic hysteresis with tension-compression asymmetry: explicit simulation based on elastoplasticity models

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Ming; Wang, Zhao-Ling; Xiao, Heng

    2015-11-01

    SMA pseudo-elastic hysteresis with tension-compression asymmetry at finite deformation may be simulated by finite elastoplastic J 2-flow models with nonlinear combined hardening, in a direct, explicit sense with no reference to any phase variables. To this goal, a novel method of treating tension-compression asymmetry is proposed, and the hardening moduli are determined directly from any two given pairs of single-variable functions shaping non-symmetric hysteresis loops in uniaxial tension and compression so that the combined hardening model thus established can automatically exactly give rise to any given shapes of non-symmetric hysteresis loops. Numerical examples show good agreement with test data.

  11. Implementation and analysis of an innovative digital charge amplifier for hysteresis reduction in piezoelectric stack actuators

    SciTech Connect

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

    2014-04-15

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

  12. Bradford Curves.

    ERIC Educational Resources Information Center

    Rousseau, Ronald

    1994-01-01

    Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)

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

    PubMed

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

    2011-12-27

    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

  14. Oscillating hysteresis in the q -neighbor Ising model

    NASA Astrophysics Data System (ADS)

    JÈ©drzejewski, Arkadiusz; Chmiel, Anna; Sznajd-Weron, Katarzyna

    2015-11-01

    We modify the kinetic Ising model with Metropolis dynamics, allowing each spin to interact only with q spins randomly chosen from the whole system, which corresponds to the topology of a complete graph. We show that the model with q ?3 exhibits a phase transition between ferromagnetic and paramagnetic phases at temperature T*, which linearly increases with q . Moreover, we show that for q =3 the phase transition is continuous and that it is discontinuous for larger values of q . For q >3 , the hysteresis exhibits oscillatory behavior—expanding for even values of q and shrinking for odd values of q . Due to the mean-field-like nature of the model, we are able to derive the analytical form of transition probabilities and, therefore, calculate not only the probability density function of the order parameter but also precisely determine the hysteresis and the effective potential showing stable, unstable, and metastable steady states. Our results show that a seemingly small modification of the kinetic Ising model leads not only to the switch from a continuous to a discontinuous phase transition, but also to an unexpected oscillating behavior of the hysteresis and a puzzling phenomenon for q =5 , which might be taken as evidence for the so-called mixed-order phase transition.

  15. Pressure-volume curves of the respiratory system.

    PubMed

    Harris, R Scott

    2005-01-01

    The quasi-static pressure-volume (P-V) curve of the respiratory system describes the mechanical behavior of the lungs and chest wall during inflation and deflation. To eliminate resistive and convective acceleration effects, the measurement of volume and pressure must be performed during short periods of apnea or during very slow flow. There are 3 main techniques for acquiring quasi-static P-V curves: the supersyringe method, the constant flow method, and the multiple-occlusion (or ventilator) method. For the information to be interpreted correctly, one must understand the interaction between the lungs and the chest wall, the effects of the supine position, and the meaning of hysteresis. The P-V curve has been studied in many disease states, but it has been applied most extensively to patients with acute respiratory distress syndrome, in hopes that it might allow clinicians to customize ventilator settings according to a patient's individual respiratory mechanics and thus protect the patient from ventilator-induced lung injury. However, lack of standardization of the procedure used to acquire P-V curves, difficulties in measuring absolute lung volume, lack of knowledge regarding how to use the information, and a paucity of data showing a benefit in morbidity and mortality with the use of P-V curves have tempered early enthusiasm regarding the clinical usefulness of the quasi-static P-V curve. PMID:15636647

  16. On the hysteresis in E to H and H to E transitions and the multistep ionization in inductively coupled plasma

    SciTech Connect

    Lee, Min-Hyong; Lee, Kyeong Hyo; Hyun, Dong-Seok; Chung, Chin-Wook

    2007-05-07

    Plasma densities, E to H and H to E transition coil currents, and electron energy distribution functions (EEDFs) are measured at various argon pressures in an inductively coupled plasma. The measured plasma density versus coil current shows that the hysteresis during the E-H transition is clearly observed only when the pressure is sufficiently high. At low gas pressures the hysteresis is not obvious. The measured EEDFs show that when the hysteresis is obvious (high pressures), electrons whose energy is not sufficient for excitation or ionization of the ground state atom are strongly depleted in the H mode. This depletion may be caused by multistep ionization. However, for the case where the hysteresis is not obvious (low pressures), the depletion due to multistep ionization is also not present. These experimental results show that the multistep ionization is a dominant factor in the E-H transition hysteresis.

  17. Identification of an extended Hammerstein system with input hysteresis nonlinearity

    E-print Network

    Wang, Jiandong

    Identification of an extended Hammerstein system with input hysteresis nonlinearity for control of an extended Hammerstein system. A point-slope-based hysteresis model is used to describe the input hysteresis. The basic idea is to separate the ascent and descent paths of the input hysteresis nonlinearity subject

  18. Inverse Compensation for Hysteresis in Magnetostrictive Transducers

    E-print Network

    Inverse Compensation for Hysteresis in Magnetostrictive Transducers Ralph C. Smith Center techniques for a class of ferromagnetic transducers including magnetostrictive actuators. If unaccommodated, magnetostrictive materials i #12; 1 Introduction Increased demands on control transducers in combination with novel

  19. Analysis of hunting in Synchronous Hysteresis Motor

    E-print Network

    Truong, Cang Kim, 1979-

    2004-01-01

    The Synchronous Hysteresis Motor has an inherent instability when it is used to drive a gyroscope wheel. The motor ideally should spin at a constant angular velocity, but it instead sporadically oscillates about synchronous ...

  20. Hysteresis and nucleation in condensed matter

    E-print Network

    Yuri Mnyukh

    2011-03-11

    The physical origin of hysteresis in condensed matter had not been previously identified. The current "science of hysteresis" is useful, but limited by phenomenological modeling. This article fills the void by revealing the exclusive cause of the hysteresis in structural, ferromagnetic and ferroelectric phase transitions, as well as upon magnetization in magnetic fields and polarization in electric fields. This exclusive cause is nucleation lags. The lags are inevitable due to the nucleation specifics, far from the classical "random fluctuation" model. A major assumption that spin orientation is determined by the orientation of its carrier explains why ferromagnetic transitions and magnetization in magnetic fields materialize by structural rearrangements at interfaces, as well as why magnetization by "rotation" is impossible. Formation of the structural and ferromagnetic hysteresis loops is considered in detail.

  1. Equivalent Circuit Modeling of Hysteresis Motors

    SciTech Connect

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

    2009-08-31

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

  2. Spatial versus time hysteresis in damping mechanisms

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  3. A combined Preisach-Hyperbolic Tangent model for magnetic hysteresis of Terfenol-D

    NASA Astrophysics Data System (ADS)

    Talebian, Soheil; Hojjat, Yousef; Ghodsi, Mojtaba; Karafi, Mohammad Reza; Mirzamohammadi, Shahed

    2015-12-01

    This study presents a new model using the combination of Preisach and Hyperbolic Tangent models, to predict the magnetic hysteresis of Terfenol-D at different frequencies. Initially, a proper experimental setup was fabricated and used to obtain different magnetic hysteresis curves of Terfenol-D; such as major, minor and reversal loops. Then, it was shown that the Hyperbolic Tangent model is precisely capable of modeling the magnetic hysteresis of the Terfenol-D for both rate-independent and rate-dependent cases. Empirical equations were proposed with respect to magnetic field frequency which can calculate the non-dimensional coefficients needed by the model. These empirical equations were validated at new frequencies of 100 Hz and 300 Hz. Finally, the new model was developed through the combination of Preisach and Hyperbolic Tangent models. In the combined model, analytical relations of the Hyperbolic Tangent model for the first order reversal loops determined the weighting function of the Preisach model. This model reduces the required experiments and errors due to numerical differentiations generally needed for characterization of the Preisach function. In addition, it can predict the rate-dependent hysteresis as well as rate-independent hysteresis.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  5. Loading-unloading hysteresis loop of randomly rough adhesive contacts

    E-print Network

    Giuseppe Carbone; Elena Pierro; Giuseppina Recchia

    2015-11-28

    In this paper we investigate the loading and unloading behavior of soft solids in adhesive contact with randomly rough profiles. The roughness is assumed to be described by a self-affine fractal on a limited range of wave-vectors. A spectral method is exploited to generate such randomly rough surfaces. The results are statistically averaged, and the calculated contact area and applied load are shown as a function of the penetration, for loading and unloading conditions. We found that the combination of adhesion forces and roughness leads to a hysteresis loading-unloading loop. This shows that energy can be lost simply as a consequence of roughness and van der Waals forces, as in this case a large number of local energy minima exist and the system may be trapped in metastable states. We numerically quantify the hysteretic loss and assess the influence of the surface statistical properties and the energy of adhesion on the hysteresis process.

  6. Hysteresis Behaviors of Poly (Naphthalene Quinone) Radical Electrorheological Fluid

    NASA Astrophysics Data System (ADS)

    Choi, Hyoung J.; Cho, Min S.; Jhon, Myung S.

    As a potential electrorheological(ER) material, poly(naphthalene quinone) radical (PNQR) ER fluid was prepared, and its rheological behavior and hysteresis phenomenon were investigated. PNQR was synthesized by Friedel-Crafts acylation between naphthalene and phthalic anhydride, using zinc chloride as a catalyst at 256°C. A Physica rheometer equipped with a high voltage generator was used to measure the rheological properties of the ER fluids, which were prepared by dispersing PNQR in silicone oil at several particle concentrations. Shear stresses were observed to decrease as shear rate increased in the region of slow deformation rate. It was further found that ER fluid showed different hysteresis behaviors according to the shear rate ranges; thixotropy was observed in the low shear rate region (0.007-0.51/s) and anti-thixotropy in the high shear rate region (0.5-10001/s). Controlled shear stress mode was also applied to observe similar behaviors.

  7. Motion of liquid drops on surfaces induced by asymmetric vibration: role of contact angle hysteresis.

    PubMed

    Mettu, Srinivas; Chaudhury, Manoj K

    2011-08-16

    Hysteresis of wetting, like the Coulombic friction at solid/solid interface, impedes the motion of a liquid drop on a surface when subjected to an external field. Here, we present a counterintuitive example, where some amount of hysteresis enables a drop to move on a surface when it is subjected to a periodic but asymmetric vibration. Experiments show that a surface either with a negligible or high hysteresis is not conducive to any drop motion. Some finite hysteresis of contact angle is needed to break the periodic symmetry of the forcing function for the drift to occur. These experimental results are consistent with simulations, in which a drop is approximated as a linear harmonic oscillator. The experiment also sheds light on the effect of the drop size on flow reversal, where drops of different sizes move in opposite directions due to the difference in the phase of the oscillation of their center of mass. PMID:21728326

  8. Modeling of the interleaved hysteresis loop in the measurements of rotational core losses

    NASA Astrophysics Data System (ADS)

    Alatawneh, Natheer; Pillay, Pragasen

    2016-01-01

    The measurement of core losses in machine laminations reveals a fundamental difference between rotational and pulsating types. Rotational core losses under rotating fields decrease at high flux density, while pulsating losses keep increasing steadily. Experimental analyses of loss components Px and Py in x and y directions with rotating fields show that the loss decreases in one loss component and sometimes attains negative values. Tracking the evolution of hysteresis loops along this loss component discloses a peculiar behavior of magnetic hysteresis, where the loop changes its path from counterclockwise to clockwise within a cycle of magnetization process, the so called interleaved hysteresis loop. This paper highlights a successful procedure for modeling the interleaved hysteresis loop in the measurement of rotational core losses in electrical machine laminations using the generalized Prandtl-Ishlinskii (PI) model. The efficiency of the proposed model is compared to Preisach model. Results and conclusion of this work are of importance toward building an accurate model of rotational core losses.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

    NASA Astrophysics Data System (ADS)

    Pinson, Matthew B.; Masoero, Enrico; Bonnaud, Patrick A.; Manzano, Hegoi; Ji, Qing; Yip, Sidney; Thomas, Jeffrey J.; Bazant, Martin Z.; Van Vliet, Krystyn J.; Jennings, Hamlin M.

    2015-06-01

    Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations of evaporable water within the fine structure of pastes, each having unique properties, and we present applied physics models that capture the hysteresis by dividing drying and rewetting into two related regimes based on relative humidity (RH). We show that a continuum model, incorporating a pore-blocking mechanism for desorption and equilibrium thermodynamics for adsorption, explains well the sorption hysteresis for a paste that remains above approximately 20% RH. In addition, we show with molecular models and experiments that water in spaces of ?1 nm width evaporates below approximately 20% RH but reenters throughout the entire RH range. This water is responsible for a drying shrinkage hysteresis similar to that of clays but opposite in direction to typical mesoporous glass. Combining the models of these two regimes allows the entire drying and rewetting hysteresis to be reproduced accurately and provides parameters to predict the corresponding dimensional changes. The resulting model can improve the engineering predictions of long-term drying shrinkage accounting also for the history dependence of strain induced by hysteresis. Alternative strategies for quantitative analyses of the microstructure of cement paste based on this mesoscale physical model of water content within porous spaces are discussed.

  11. Titration and hysteresis in epigenetic chromatin silencing

    NASA Astrophysics Data System (ADS)

    Dayarian, Adel; Sengupta, Anirvan M.

    2013-06-01

    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.

  12. Hysteresis in the Central African Rainforest

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Fatigue, hysteresis, and acoustic emission, parts 1 and 2

    NASA Astrophysics Data System (ADS)

    Guralnick, S. A.; Erber, T.

    1992-05-01

    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 fatigue is similar to the progressive failure of structures under cyclic loading. And, specifically, that the endurance limit of a material in fatigue is the analogue of the incremental collapse load of a structure. Since the principal features of the service life and failure of structures can be completely described by hysteresis methods, it is plausible that similar means can be used to characterize the inception and organization of microplastic processes in materials. Experiments were conducted upon nearly 100 specimens made of Rimmed AISI 1018 Unannealed Steel. This material was selected because extensive data on its performance exists in the engineering literature and because its stress-strain curve is of the gradual yielding type, mirroring at least the monotonic stress-strain behavior of many of the kinds of metals used in the aircraft industry.

  14. Hysteresis and Wavenumber Vacillation in Unstable Baroclinic Flows

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. Cosmological hysteresis and the cyclic universe

    NASA Astrophysics Data System (ADS)

    Sahni, Varun; Toporensky, Aleksey

    2012-06-01

    A universe filled with a homogeneous scalar field exhibits “cosmological hysteresis.” Cosmological hysteresis is caused by the asymmetry in the equation of state during expansion and contraction. This asymmetry results in the formation of a hysteresis loop: ?pdV, whose value can be nonvanishing during each oscillatory cycle. For flat potentials, a negative value of ?pdV leads to the increase in amplitude of consecutive cycles and to a universe with older and larger successive cycles. Such a universe appears to possess an arrow of time even though entropy production is absent and all of the equations respect time-reversal symmetry. Cosmological hysteresis appears to be widespread and exists for a large class of scalar-field potentials and mechanisms for making the universe bounce. For steep potentials, the value of ?pdV can be positive as well as negative. The expansion factor in this case displays quasiperiodic behavior in which successive cycles can be both larger as well as smaller than previous ones. This quasiregular pattern resembles the phenomenon of beats displayed by acoustic systems. Remarkably, the expression relating the increase or decrease in oscillatory cycles to the quantum of hysteresis appears to be model independent. The cyclic scenario is extended to spatially anisotropic models and it is shown that the anisotropy density decreases during successive cycles if ?pdV is negative.

  16. Power-laws in the dynamic hysteresis of quantum nonlinear photonic resonators

    E-print Network

    W. Casteels; F. Storme; A. Le Boité; C. Ciuti

    2015-09-07

    We explore theoretically the physics of dynamic hysteresis for driven-dissipative nonlinear photon resonators. In the regime where the semiclassical mean-field theory predicts bistability, the exact steady-state density matrix is known to be unique, being a statistical mixture of two states: in particular, no static hysteresis cycle of the excited population occurs as a function of the driving intensity. Here, we predict that in the quantum regime a {\\it dynamic} hysteresis with a rich phenomenology does appear when sweeping the driving amplitude in a finite time. The hysteresis area as a function of the sweep time reveals a power-law decay with an universal exponent, with a behavior qualitatively different from the mean-field predictions. The dynamic hysteresis power-law defines a characteristic time, which depends dramatically on the size of the nonlinearity and on the frequency detuning between the driving and the resonator. In the strong nonlinearity regime, the characteristic time oscillates as a function of the intrinsic system parameters due to multiphotonic resonances. We also consider the case of two coupled driven-dissipative nonlinear resonators, showing that dynamic hysteresis and power-law behavior occur also in presence of correlations between the resonators. Our theoretical predictions can be explored in a broad variety of physical systems, e.g., circuit QED superconducting resonators and semiconductor optical microcavities.

  17. Influence of hydraulic hysteresis on the mechanical behavior of unsaturated soils and interfaces

    NASA Astrophysics Data System (ADS)

    Khoury, Charbel N.

    Unsaturated soils are commonly widespread around the world, especially at shallow depths from the surface. The mechanical behavior of this near surface soil is influenced by the seasonal variations such as rainfall or drought, which in turn may have a detrimental effect on many structures (e.g. retaining walls, shallow foundations, mechanically stabilized earth walls, soil slopes, and pavements) in contact with it. Thus, in order to better understand this behavior, it is crucial to study the complex relationship between soil moisture content and matric suction (a stress state variable defined as pore air pressure minus pore water pressure) known as the Soil Water Characteristic Curve (SWCC). In addition, the influence of hydraulic hysteresis on the behavior of unsaturated soils, soil-structure interaction (i.e. rough and smooth steel interfaces, soil-geotextile interfaces) and pavement subgrade (depicted herein mainly by resilient modulus, Mr) was also studied. To this end, suction-controlled direct shear tests were performed on soils, rough and smooth steel interfaces and geotextile interface under drying (D) and wetting after drying (DW). The shearing behavior is examined in terms of the two stress state variables, matric suction and net normal stress. Results along the D and DW paths indicated that peak shear strength increased with suction and net normal stress; while in general, the post peak shear strength was not influenced by suction for rough interfaces and no consistent trend was observed for soils and soil-geotextiles interfaces. Contrary to saturated soils, results during shearing at higher suction values (i.e. 25 kPa and above) showed a decrease in water content eventhough the sample exhibited dilation. A behavior postulated to be related to disruption of menisci and/or non-uniformity of pore size which results in an increase in localized pore water pressures. Interestingly, wetting after drying (DW) test results showed higher peak and post peak shear strength than that of the drying (D) tests. This is believed to be the result of many factors such as: (1) cyclic suction stress loading, (2) water content (less on wetting than drying), and (3) type of soil. The cyclic suction loading may have induced irrecoverable plastic strains, resulting in stiffer samples for wetting tests as compared to drying. Additionally, water may be acting as a lubricant and thus resulting in lower shear strength for test samples D with higher water contents than DW samples. Furthermore, various shear strength models were investigated for their applicability to the experimental data. Models were proposed for the prediction of shear strength with suction based on the SWCC. The models are able to predict the shear strength of unsaturated soil and interfaces due to drying and wetting (i.e. hydraulic hysteresis) by relating directly to the SWCC. The proposed models were used and partly validated by predicting different test results from the literature. In addition, an existing elastoplastic constitutive model was investigated and validated by comparing the predicted and experimental (stress-displacement, volume change behavior) results obtained from rough and geotextile interface tests. This study also explores the effect of hydraulic hysteresis on the resilient modulus (Mr) of subgrade soils. Suction-controlled Mr tests were performed on compacted samples along the primary drying, wetting, secondary drying and wetting paths. Two test types were performed to check the effect of cyclic deviatoric stress loading on the results. First, M r tests were performed on the same sample at each suction (i.e. 25, 50, 75, 100 kPa) value along all the paths (drying, wetting etc.). A relationship between resilient modulus (Mr) and matric suction was obtained and identified as the resilient modulus characteristic curve (MRCC). MRCC results indicated that Mr increased with suction along the drying curve. On the other hand, results on the primary wetting indicated higher Mr than that of the primary drying and the secondary drying. The second type of test

  18. Thermally induced all-optical inverter and dynamic hysteresis loops in graphene oxide dispersions.

    PubMed

    Melle, Sonia; Calderón, Oscar G; Egatz-Gómez, Ana; Cabrera-Granado, E; Carreño, F; Antón, M A

    2015-11-01

    We experimentally study the temporal dynamics of amplitude-modulated laser beams propagating through a water dispersion of graphene oxide sheets in a fiber-to-fiber U-bench. Nonlinear refraction induced in the sample by thermal effects leads to both phase reversing of the transmitted signals and dynamic hysteresis in the input-output power curves. A theoretical model including beam propagation and thermal lensing dynamics reproduces the experimental findings. PMID:26560566

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

    SciTech Connect

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

    1988-11-15

    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.

  20. CHIN.PHYS.LETT. Vol. 25, No. 5 (2008) 1788 Dynamic Simulation for Hysteresis in Shape Memory Alloy under Tension

    E-print Network

    Tang, Shaoqiang

    2008-01-01

    -strain curve exhibits a big hysteresis loop, which quantitatively agrees with the experimental results. PACS transitions are regarded well understood at microscopic level by theories of renormalization group, non band, when the strain exceeds 1.7%. The vol- ume ratio of martensitic band increases along

  1. Bayesian analysis of stage-discharge relationships affected by hysteresis and quantification of the associated uncertainties

    NASA Astrophysics Data System (ADS)

    Mansanarez, Valentin; Le Coz, Jérôme; Renard, Benjamin; Lang, Michel; Birgand, François

    2015-04-01

    The hysteresis effect is a hydraulic phenomenon associated with transient flow in a relatively flat channel. Hysteresis leads to non-univocal stage-discharge relationships: for a given stage, discharge during the rising limb is greater than during the recession. Hysteresis occurs in open-channel flows because the velocity pressure wave usually propagates faster than the pressure wave. In practice, hysteresis is often ignored when developing hydrometric rating curves, leading to biased flood hydrographs. When hysteresis is not ignored, the most common practice is to correct the univocal rating curve by using the simple Jones formula. This formula requires the estimation of different physical variables through numerical modelling and/or expertise. The estimation of the associated discharge uncertainty is still an open question. The Bayesian method proposed in this presentation incorporates information from both hydraulic knowledge (equations of channel controls based on geometry and roughness estimates) and stage-discharge observations (gauging data). The obtained total uncertainty combines parametric uncertainty (unknown rating curve parameters) and structural uncertainty (imperfection of the rating curve model). This method provides a direct estimation of the physical inputs of the rating curve (roughness, bed slope, kinematic wave celerity, etc.). Two hysteresis formulas were used: the most widely-used Jones formula and its expansion to the 3rd order, known as the Fenton formula. The wave celerity may be either constant or expressed as a simple function of stage based on the kinematic wave assumption. This method has been applied to one data set. Sensitivity tests allowed us to draw the following conclusions. As expected, more precise hydraulic priors and/or less uncertain gaugings provide rating curves that agree well with discharge measurements and have a smaller uncertainty. The simple Jones formula leads to as good results as the more complex Fenton formula. Moreover, the kinematic wave celerity yielded less uncertain discharges than the constant celerity option. In the absence of rating shifts, the hysteretic rating curve estimated during a given flood event can be applied to subsequent events with the same accuracy. The calibration can also be made using gaugings from different events. Furthermore, this method does not detect hysteresis when it is applied to well-known and well-identifiable univocal stage-discharge relation. Finally, an analysis of the best gauging strategy demonstrates than, for a hysteretic flow event, the most common strategy, i.e. to gauge during the falling limb near the peak flow, yields high uncertainties in the rising limb and a biased identification of the hysteresis amplitude The best strategy is to gauge near a few remarkable points of the flood wave (min and max stage, max discharge, min and max stage gradient), not necessarily during a single event.

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

    SciTech Connect

    Ganow, H.C.

    1985-08-01

    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.

  3. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    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.

  4. Reduction of hysteresis in PI-controlled systems

    SciTech Connect

    Krakow, K.I.

    1998-10-01

    Motorized dampers and valves generally possess some hysteresis. Hysteresis may result in poor repeatability of experimental data. It also may result in the deviation of a response of a proportional integral (PI) controlled system from its target response and in hunting. In some applications, it may be desirable to reduce the effects of hysteresis. A method to reduce the effects of hysteresis is presented here. This method is based on software, not hardware, modification.

  5. Circuit increases capability of hysteresis synchronous motor

    NASA Technical Reports Server (NTRS)

    Markowitz, I. N.

    1967-01-01

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

  6. Managing Hysteresis: Three Cornerstones to Fiscal Stability

    ERIC Educational Resources Information Center

    Weeks, Richard

    2012-01-01

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

  7. Sorption Hysteresis of Benzene in Charcoal Particles

    E-print Network

    Muzzio, Fernando J.

    Sorption Hysteresis of Benzene in Charcoal Particles W A S H I N G T O N J . B R A I D A , , J O (benzene) in water to a maple- wood charcoal prepared by oxygen-limited pyrolysis at 673 K. Gas adsorption m2/g, and appreciable porosity in ultramicropores Benzene sorption- desorption conditions

  8. Design of hysteresis circuits using differential amplifiers

    NASA Technical Reports Server (NTRS)

    Cooke, W. A.

    1971-01-01

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

  9. Flexible pivot mount eliminates friction and hysteresis

    NASA Technical Reports Server (NTRS)

    Highman, C. O.

    1970-01-01

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

  10. Vector magnetic hysteresis of hard superconductors and C. Lopez2

    E-print Network

    Majós, Antonio Badía

    Vector magnetic hysteresis of hard superconductors A. Badi´a1 and C. Lo´pez2 1 Departamento de Fi hysteresis. Both features are a manifestation of the nonequilibrium thermodynamic processes which take place type-II materials develop such a pronounced hysteresis that the reversible contribution from

  11. Control of hysteresis: theory and experimental results , Ram Venkataraman

    E-print Network

    Iyer, Ram Venkataraman

    Control of hysteresis: theory and experimental results Xiaobo Tan , Ram Venkataraman , and P. S ABSTRACT Hysteresis in smart materials hinders the wider applicability of such materials in actuators. In this paper, a systematic approach for coping with hysteresis is presented. The method is illustrated through

  12. PID Control of Second-Order Systems with Hysteresis

    E-print Network

    Ryan, E.P.

    PID Control of Second-Order Systems with Hysteresis Bayu Jayawardhana, Hartmut Logemann & Eugene P. Keywords. Hysteresis, Nonlinear systems, PID control, Tuning regulators. 1 Introduction With reference of form (2) exhibit hysteresis phenomena, a particular example of which is the "hysteric spring" model

  13. Hysteresis Inverse Iterative Learning Control of Piezoactuators in AFM

    E-print Network

    Leang, Kam K.

    Hysteresis Inverse Iterative Learning Control of Piezoactuators in AFM S. C. Ashley, U. Aridogan, R update law exploits an inverse model of the hysteresis behavior for piezoactuators. Compared to ILC for hysteresis that updates the control input using the measured tracking error scaled by a constant (fixed

  14. Mathematical models of hydrological systems with Preisach hysteresis

    E-print Network

    Schellekens, Michel P.

    Mathematical models of hydrological systems with Preisach hysteresis P. Krejci, P. O'Kane, A. Pokrovskii, D. Rachinskii 1 Introduction The important role of hysteresis in hydrology and soil physics is known for a long time. Hysteresis manifests itself through the fact that it is easier (i.e., less thermo

  15. Relaxed model for the hysteresis in micromagnetism , M. Effendiev2

    E-print Network

    Carbou, Gilles

    Relaxed model for the hysteresis in micromagnetism G. Carbou1 , M. Effendiev2 and P. Fabrie1 1 Math, Germany. Abstract : in this paper we study a model of ferromagnetic material with hysteresis effects modelling the hysteresis. This term takes the form of a maximal monotone operator acting on the time

  16. A TemperatureDependent Hysteresis Model for Relaxor Ferroelectrics

    E-print Network

    A Temperature­Dependent Hysteresis Model for Relaxor Ferroelectrics Ralph C. Smith 1 and Craig L polarization and distribution of regions as a function of temperature. Hysteresis below the freezing point and hysteresis exhibited by the materials through a wide range of temperatures and input drive levels

  17. A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith

    E-print Network

    A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith Center for Research in Scientific.hom@lmco.com Abstract This paper addresses the modeling of hysteresis in ferroelectric materials through consideration for the anhysteretic polarization that occurs in the absence of domain wall pinning. In the second step, hysteresis

  18. Periodic orbits in the ODEs with hysteresis perturbations

    E-print Network

    Schellekens, Michel P.

    Periodic orbits in the ODEs with hysteresis perturbations A. Pokrovskii Dept. of Applied for the robustness of the unsta- ble oscillations in nonlinear ODE with respect to the small hysteresis perturbations was the interest to the influence of the small hysteresis perturbations to the dynamics of the physical systems

  19. Hysteresis and Economics Taking the economic past into account

    E-print Network

    Lamba, Harbir

    Hysteresis and Economics Taking the economic past into account R. Cross M. Grinfeld H. Lamba of hysteresis to economic models. In particular, we explain why many aspects of real economic systems, for example, in [1], which is also one of the first works in economics to mention hysteresis explicitly (but

  20. HYSTERESIS-BASED SWITCHING CONTROL OF STOCHASTIC LINEAR SYSTEMS

    E-print Network

    Hespanha, João Pedro

    HYSTERESIS-BASED SWITCHING CONTROL OF STOCHASTIC LINEAR SYSTEMS Maria Prandini£ , Jo~ao P. Hespanha. Abstract We study hysteresis-based switching control for a class of discrete-time stochastic linear systems exceeds its minimum (over all admissible models) by a certain hysteresis factor. The con- troller

  1. AN ENERGY-BASED HYSTERESIS MODEL FOR MAGNETOSTRICTIVE TRANSDUCERS

    E-print Network

    Flatau, Alison B.

    AN ENERGY-BASED HYSTERESIS MODEL FOR MAGNETOSTRICTIVE TRANSDUCERS F.T. Calkins Department@iastate.edu Abstract This paper addresses the modeling of hysteresis in magnetostrictive transducers;cant nonlinearities and hysteresis due to inherent properties of mag- netostrictive materials

  2. A Stress-Dependent Hysteresis Model for Ferroelectric Materials

    E-print Network

    A Stress-Dependent Hysteresis Model for Ferroelectric Materials Brian L. Ball 1 , Ralph C. Smith 2, is the presence of hysteresis and constitutive nonlinearities due to the noncen- trosymmetric structure relations provide reasonable accuracy. At higher drive levels, however, the hysteresis and nonlinearities

  3. On regularity properties of solutions to hysteresis-type problems

    E-print Network

    On regularity properties of solutions to hysteresis-type problems D.E. Apushkinskaya and N (distributional) sence. Here L = xx - t is the heat operator, B1 = {x R : |x| hysteresis) means that the hysteresis function Hu(x, t) takes for u(x, t) (, ) the same value as at the previous

  4. Subharmonic ferroresonance in an LCR circuit with hysteresis

    E-print Network

    Lamba, Harbir

    Subharmonic ferroresonance in an LCR circuit with hysteresis H. LAMBA # M.GRINFELD # S.McKEE # R. SIMPSON + Abstract We use the Preisach model of magnetic hysteresis to model the inductance in a series LCR circuit. By introducing a hysteresis parameter into the Preisach functions used, we are able

  5. Torque meter aids study of hysteresis motor rings

    NASA Technical Reports Server (NTRS)

    Cole, M.

    1967-01-01

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

  6. A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith

    E-print Network

    A Domain Wall Theory for Ferroelectric Hysteresis Ralph C. Smith Center for Research in Scienti c.hom@lmco.com Abstract This paper addresses the modeling of hysteresis in ferroelectric materials through consideration for the anhysteretic polarization that occurs in the absence of domain wall pinning. In the second step, hysteresis

  7. Lift hysteresis at stall as an unsteady boundary-layer phenomenon

    NASA Technical Reports Server (NTRS)

    Moore, Franklin K

    1956-01-01

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

  8. Basin of Attraction Determines Hysteresis in Explosive Synchronization

    E-print Network

    Yong Zou; Tiago Pereira; Michael Small; Zonghua Liu; Jürgen Kurths

    2014-02-11

    Spontaneous explosive emergent behavior takes place in heterogeneous networks when the frequencies of the nodes are positively correlated to the node degree. A central feature of such explosive transitions is a hysteretic behavior at the transition to synchronization. We unravel the underlying mechanisms and show that the dynamical origin of the hysteresis is a change of basin of attraction of the synchronization state. Our findings hold for heterogeneous networks with star graph motifs such as scale free networks, and hence reveal how microscopic network parameters such as node degree and frequency affect the global network properties and can be used for network design and control.

  9. Hysteresis effects of changing the parameters of noncooperative games.

    PubMed

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

    2012-03-01

    We adapt the method used by Jaynes to derive the equilibria of statistical physics to instead derive equilibria of bounded rational game theory. We analyze the dependence of these equilibria on the parameters of the underlying game, focusing on hysteresis effects. In particular, we show that by gradually imposing individual-specific tax rates on the players of the game, and then gradually removing those taxes, the players move from a poor equilibrium to one that is better for all of them. PMID:22587144

  10. Anomalous hysteresis properties of iron films deposited on liquid surfaces

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

  11. Thermal hysteresis of some important physical properties of nanoparticles.

    PubMed

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

    2008-11-01

    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 which it is seeded. The thermal responses of zeta potential and conductivity profile are found to be independent of the surface conjugation with the later being subjected to a phase transition phenomenon as revealed by a temperature criticality. PMID:18760800

  12. Origin of hysteresis in bed form response to unsteady flows

    NASA Astrophysics Data System (ADS)

    Martin, Raleigh L.; Jerolmack, Douglas J.

    2013-03-01

    Field and laboratory studies indicate that changes in riverbed morphology often lag changes in water discharge. This lagged response produces hysteresis in the relationship between water discharge and bed form geometry. To understand these phenomena, we performed flume experiments to observe the response of a sand bed to step increases and decreases in water discharge. For an abrupt rise in discharge, we observed that bed forms grew rapidly by collision and merger of bed forms migrating with different celerities. Growth rate slowed as bed forms approached equilibrium with the higher discharge regime. After an abrupt discharge drop, bed form decay occurred through formation of smaller secondary bed forms, in equilibrium with the lower discharge, which cannibalized the original, relict features. We present a simple model framework to quantitatively predict time scales of bed form adjustment to flow changes, based on equilibrium bed form heights, lengths, and celerities at low and high flows. For rising discharge, the model assumes that all bed form collisions result in irreversible merger, due to a dispersion of initial celerities. For falling discharge, we derive a diffusion model for the decay of relict high-stage features. Our models predict the form and time scale of experimental bed form adjustments. Additional experiments applying slow and fast triangular flood waves show that bed form hysteresis occurs only when the time scale of flow change is faster than the modeled (and measured) bed form adjustment time. We show that our predicted adjustment time scales can also be used to predict the occurrence of bed form hysteresis in natural floods.

  13. Hysteresis-based analysis of overland metal transport

    NASA Astrophysics Data System (ADS)

    Mishra, Surendra Kumar; Sansalone, J. J.; Singh, Vijay P.

    2003-06-01

    Introducing a concept of equivalent mass depth of flow, this study describes the phenomenon of non-point source pollutant (metal) transport for pavement (or overland) flow in analogy with wave propagation in wide open channels. Hysteretic and normal mass rating curves are developed for runoff rate and mass of 12 dissolved and particulate-bound metal elements (pollutants) using the rainfall-runoff and water quality data of the 15 × 20 m2 instrumented pavement in Cincinnati, USA. Normal mass rating curves developed for easy computation of pollutant load are found to be of a form similar to Manning's, which is valid for open channel flows. Based on the hysteresis analysis, wave types for dissolution and mixing of particulate-bound metals are identified. The analysis finds that the second-order partial-differential equation normally used for metal transport does not have the efficacy to describe fully the strong non-linear phenomena such as is described for various metal elements by dynamic waves. In addition, the proportionality concept of the popular SCS-CN concept is extended for determining the potential maximum metal mass Mp of all the 12 elements transported by a rain storm and related to the antecedent dry period (ADP). For the primary metal zinc element, Mp is found to increase with the ADP and vice versa.

  14. Comparison of CO2 trapping in highly heterogeneous reservoirs with Brooks-Corey and van Genuchten type capillary pressure curves

    E-print Network

    Gershenzon, Naum I; Dominic, David F; Mehnert, Edward; Okwen, Roland T

    2015-01-01

    Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Previously we showed how the dynamics of a CO2 plume is influenced by the multi-scale stratal architecture in deep saline reservoirs. The results strongly suggest that representing small-scale features is critical to understanding capillary trapping processes. Here we present the result of simulation of CO2 trapping using two different conventional approaches, i.e. Brooks-Corey and van Genuchten, for the capillary pressure curves. We showed that capillary trapping and dissolution rates are very different for the Brooks-Corey and van Genuchten approaches when heterogeneity and hysteresis are both represented.

  15. Interactive effect of hysteresis and surface chemistry on gated silicon nanowire gas sensors.

    PubMed

    Paska, Yair; Haick, Hossam

    2012-05-01

    Gated silicon nanowire gas sensors have emerged as promising devices for chemical and biological sensing applications. Nevertheless, the performance of these devices is usually accompanied by a "hysteresis" phenomenon that limits their performance under real-world conditions. In this paper, we use a series of systematically changed trichlorosilane-based organic monolayers to study the interactive effect of hysteresis and surface chemistry on gated silicon nanowire gas sensors. The results show that the density of the exposed or unpassivated Si-OH groups (trap states) on the silicon nanowire surface play by far a crucial effect on the hysteresis characteristics of the gated silicon nanowire sensors, relative to the effect of hydrophobicity or molecular density of the organic monolayer. Based on these findings, we provide a tentative model-based understanding of (i) the relation between the adsorbed organic molecules, the hysteresis, and the related fundamental parameters of gated silicon nanowire characteristics and of (ii) the relation between the hysteresis drift and possible screening effect on gated silicon nanowire gas sensors upon exposure to different analytes at real-world conditions. The findings reported in this paper could be considered as a launching pad for extending the use of the gated silicon nanowire gas sensors for discriminations between polar and nonpolar analytes in complex, real-world gas mixtures. PMID:22524252

  16. Hysteresis in the trade cycle

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  17. Shape fluctuation-induced dynamic hysteresis

    NASA Astrophysics Data System (ADS)

    Das, Moupriya; Mondal, Debasish; Ray, Deb Shankar

    2012-03-01

    We consider a system of Brownian particles confined in a two-dimensional bilobal enclosure whose walls are driven in time periodically by an external perturbation. The response of the particles under shape modulation is characterized by a relaxational delay which results in a non-vanishing area of the response function—field loop, response function being the integrated probability of residence of the particles in any of the lobes. This phenomenon is an entropic analogue of dynamical hysteresis, which vanishes in the quasi-static limit. The hysteresis loop area depends on temperature, strength of modulating field, and the geometrical parameters of the enclosure and exhibits a turnover as a function of frequency of the field.

  18. Wetting Hysteresis at the Molecular Scale

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  19. "The Show"

    ERIC Educational Resources Information Center

    Gehring, John

    2004-01-01

    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…

  20. Magnetic hysteresis, compensation behaviors, and phase diagrams of bilayer honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Ersin, Kantar

    2015-10-01

    Magnetic behaviors of the Ising system with bilayer honeycomb lattice (BHL) structure are studied by using the effective-field theory (EFT) with correlations. The effects of the interaction parameters on the magnetic properties of the system such as the hysteresis and compensation behaviors as well as phase diagrams are investigated. Moreover, when the hysteresis behaviors of the system are examined, single and double hysteresis loops are observed for various values of the interaction parameters. We obtain the L-, Q-, P-, and S-type compensation behaviors in the system. We also observe that the phase diagrams only exhibit the second-order phase transition. Hence, the system does not show the tricritical point (TCP).

  1. A high-performance angular speed measurement method based on adaptive hysteresis switching techniques

    NASA Astrophysics Data System (ADS)

    Huang, Haiming; Chou, Wusheng; Zhang, Zuojiang

    2015-12-01

    The high-performance measurement of angular speed (AS) is an essential requirement for achieving the high accuracy of machine control and monitoring. This paper proposes a new adaptive AS measurement system, which minimizes AS errors and fluctuations from conventional AS methods in a wide range of AS measurement. Unlike the conventional switches used previously, the system is composed of two layers of hysteresis switches, hereinafter referred to as the inner and outer hysteresis switch, respectively, to count pulses from an optical encoder adaptively. To highlight the key techniques used, the system is named as a hysteresis switch-based adaptation AS measurement (HS-AASM). The proposed method is designed and implemented based on a cost-effective TMS320F28335 digital signal controller (DSC). The performance analyses and experimental verifications show that the HS-AASM method outperforms the existing methods.

  2. Rheological hysteresis in soft glassy materials

    E-print Network

    Thibaut Divoux; Vincent Grenard; Sébastien Manneville

    2012-12-05

    The nonlinear rheology of a soft glassy material is captured by its constitutive relation, shear stress vs shear rate, which is most generally obtained by sweeping up or down the shear rate over a finite temporal window. For a huge amount of complex fluids, the up and down sweeps do not superimpose and define a rheological hysteresis loop. By means of extensive rheometry coupled to time-resolved velocimetry, we unravel the local scenario involved in rheological hysteresis for various types of well-studied soft materials. We introduce two observables that quantify the hysteresis in macroscopic rheology and local velocimetry respectively, as a function of the sweep rate \\delta t^{-1}. Strikingly, both observables present a robust maximum with \\delta t, which defines a single material-dependent timescale that grows continuously from vanishingly small values in simple yield stress fluids to large values for strongly time-dependent materials. In line with recent theoretical arguments, these experimental results hint at a universal timescale-based framework for soft glassy materials, where inhomogeneous flows characterized by shear bands and/or pluglike flow play a central role.

  3. Performance catastrophes in sport: a test of the hysteresis hypothesis.

    PubMed

    Hardy, L; Parfitt, G; Pates, J

    1994-08-01

    An experiment is reported which tests Fazey and Hardy's (1988) catastrophe model of anxiety and performance. Eight experienced crown green bowlers performed a bowling task under conditions of high and low cognitive anxiety. On each of these occasions, physiological arousal (measured by heart rate) was manipulated by means of physical work in such a way that the subjects were tested with physiological arousal increasing and decreasing. A repeated-measures three-factor ANOVA was used to test the hysteresis hypothesis that the performance x heart rate graph would follow a different path for heart rate increasing compared with heart rate decreasing in the high cognitive anxiety condition, but not in the low cognitive anxiety condition. The ANOVA revealed the predicted three-way interaction of cognitive anxiety, heart rate, and the direction of change in heart rate upon performance, with follow-up tests indicating that the interaction was due to hysteresis occurring in the high cognitive anxiety condition but not in the low cognitive anxiety condition. Other statistical procedures showed that, in the high cognitive anxiety condition, subjects' best performances were significantly better, and their worst performances significantly worse, than in the low cognitive anxiety condition. However, the results did not provide unequivocal support for the catastrophe model of anxiety and performance. PMID:7932942

  4. Modeling Hysteresis Effect in Three-Phase Relative Permeability

    NASA Astrophysics Data System (ADS)

    Kianinejad, A.; Chen, X.; DiCarlo, D. A.

    2014-12-01

    Simulation and fluid flow prediction of many petroleum enhanced oil recovery methods as well as environmental processes such as carbon dioxide (CO2) geological storage requires accurate modeling and determination of relative permeability under different saturation histories. Based on this critical need, there has been several different three-phase relative permeability models developed to predict the hysteresis effects in relative permeability, most of which requiring many different parameters which introduce extreme complexity to the models for practical purposes. In this work, we experimentally measured three-phase, water/oil/gas, relative permeability in a 1-m long water-wet sand pack, under several different flow histories. We measured the in-situ saturations along the sand pack using a CT scanner. We then determined the relative permeabilities directly from the measured in-situ saturations, using unsteady-state method. Based on our results, good estimation of residual saturations yields in excellent three-phase relative permeability estimations by just using the simple, standard relative permeability models such as, Saturation Weighted Interpolation (SWI), Corey's and Stones. Our results show that, the key parameter to model the hysteresis in three-phase relative permeability (effect of saturation history) is the residual saturations. Once the residual saturations were correctly determined for each specific saturation path, the standard relative permeability models can predict the three-phase relative permeabilities perfectly.

  5. Monopoles, Curves and Ramanujan

    E-print Network

    H. W. Braden; V. Z. Enolski

    2007-04-30

    We develop the Ercolani-Sinha construction of SU(2) monopoles and make this effective for (a five parameter family of centred) charge 3 monopoles. In particular we show how to solve the transcendental constraints arising on the spectral curve. For a class of symmetric curves the transcendental constraints become a number theoretic problem and a recently proven identity of Ramanujan provides a solution.

  6. Hysteresis compensation and trajectory preshaping for piezoactuators in scanning applications

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    This paper focuses on the dynamics and control of piezoactuators (PEAs) for high-speed large-range scanning applications. Firstly, the nonlinear hysteresis is modeled by using a modified Maxwell resistive capacitor (MRC) model. Secondly, an inverse-based feedforward controller is proposed for this application with hysteresis compensation. Then, the scanning trajectories are preshaped by treating the hysteresis-compensated PEA as a linear system. Finally, experiments are conducted to verify the effectiveness of the proposed approaches.

  7. Method and apparatus for sub-hysteresis discrimination

    DOEpatents

    De Geronimo, Gianluigi

    2015-12-29

    Embodiments of comparator circuits are disclosed. A comparator circuit may include a differential input circuit, an output circuit, a positive feedback circuit operably coupled between the differential input circuit and the output circuit, and a hysteresis control circuit operably coupled with the positive feedback circuit. The hysteresis control circuit includes a switching device and a transistor. The comparator circuit provides sub-hysteresis discrimination and high speed discrimination.

  8. Conformational electroresistance and hysteresis in nanoclusters.

    PubMed

    Li, Xiang-Guo; Zhang, X-G; Cheng, Hai-Ping

    2014-08-13

    The existence of multiple thermodynamically stable isomer states is one of the most fundamental properties of small clusters. This work shows that the conformational dependence of the Coulomb charging energy of a nanocluster leads to a giant electroresistance, where charging induced conformational distortion changes the blockade voltage. The intricate interplay between charging and conformation change is demonstrated in a nanocluster Zn3O4 by combining a first-principles calculation with a temperature-dependent transport model. The predicted hysteretic Coulomb blockade staircase in the current-voltage curve adds another dimension to the rich phenomena of tunneling electroresistance. The new mechanism provides a better controlled and repeatable platform to study conformational electroresistance. PMID:24987929

  9. Conformational electroresistance and hysteresis in nanoclusters

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Guo; Zhang, Xiao-Guang; Cheng, Hai-Ping

    2015-03-01

    Abstract: Existence of multiple thermodynamically stable isomer states is one of the most fundamental properties of small clusters. We show that the conformational dependence of the Coulomb charging energy of a nanocluster leads to a giant electroresistance, where charging induced conformational distortion changes the blockade voltage. The intricate interplay between charging and conformation change is demonstrated in a nanocluster Zn3O4 by combining a first-principles calculation with a temperature-dependent transport model. The predicted hysteretic Coulomb blockade staircase in the current-voltage curve adds another dimension to the rich phenomena of tunneling electroresistance. The new mechanism provides a better controlled and repeatable platform to study conformational electroresistance. Acknowledgement: DOE/BES-DE-FG02-02ER45995; NERSC.

  10. Hysteresis behaviors of a spin-1 anisotropic Heisenberg model

    NASA Astrophysics Data System (ADS)

    Ak?nc?, Ümit

    2016-01-01

    The hysteresis behaviors of anisotropic S-1 Heisenberg model have been studied within the effective field theory with two spin cluster. After giving the phase diagrams, the effect of the crystal field and anisotropy in the exchange interaction on the hysteresis loops has been determined. One important finding is the observation of double hysteresis loops in the low temperature and negative crystal field region. Double hysteresis loops disappear as the exchange anisotropy decreases. This behavior has been investigated carefully and physical explanation has also been given briefly.

  11. Theory of the hysteresis loop in ferromagnets 

    E-print Network

    Lyuksyutov, Igor F.; Nattermann, T.; Pokrovsky, Valery L.

    1999-01-01

    are much less known. There are only few articles devoted to the HL in ultrathin ferromagnetic films,10,11,7?9 though the hysteresis effects have been found as a side effect in many others ~see, for example, Refs. 12 and 13!. Critical exponents found...-1829/99/59~6!/4260~13!/$15.00 loop in ferromagnets v* , College Station, Texas 77843-4242 n a?t zu Ko?ln, 50937, Ko?ln, Germany , 24 rue Lhomond 75231, Paris Cedex 05, France y , College Station, Texas 77843-4242 l Physics, Moscow, Russia y 1998! a in alternating magnetic...

  12. Hysteresis prediction inside magnetic shields and application

    SciTech Connect

    Mori?, Igor; De Graeve, Charles-Marie; Grosjean, Olivier; Laurent, Philippe

    2014-07-15

    We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60??T. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission.

  13. Proximity effect induced magnetoresistance hysteresis loops in a topological insulator/YIG heterostructure

    NASA Astrophysics Data System (ADS)

    Montazeri, Mohammad; Lang, Murong; Onbasli, Mehmet C.; Kou, Xufeng; He, Liang; Ross, Caroline A.; Wang, Kang L.

    2014-03-01

    We experimentally demonstrate the proximity effect induced hysteretic magnetoresistance in an 8 quintuple layers of Bi2Se3 films grown on Gallium Gadolinium Garnet (GGG) (111) substrates with a 50 nm Yttrium Iron Garnet (YIG) buffer layer by molecular beam epitaxy. With in-plane and out-of-plane magnetic field, square wave shaped and butterfly shaped resistance hysteresis loops can be observed up to 25 K, respectively. The relationship between the hysteretic MR curves and the magnetic switching of the YIG will be discussed in the context of a proximity effect between the YIG and the TI.

  14. Terrestrial Exoplanet Light Curves

    E-print Network

    Eric Gaidos; Nicholas Moskovitz; Darren M. Williams

    2005-11-23

    The phase or orbital light curves of extrasolar terrestrial planets in reflected or emitted light will contain information about their atmospheres and surfaces complementary to data obtained by other techniques such as spectrosopy. We show calculated light curves at optical and thermal infrared wavelengths for a variety of Earth-like and Earth-unlike planets. We also show that large satellites of Earth-sized planets are detectable, but may cause aliasing effects if the lightcurve is insufficiently sampled.

  15. The Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors

    E-print Network

    Lee, Alpha A; Goriely, Alain; Kondrat, Svyatoslav

    2015-01-01

    Nanoporous supercapacitors are an important player in the field of energy storage that fill the gap between dielectric capacitors and batteries. The key challenge in the development of supercapacitors is the perceived tradeoff between capacitance and power delivery. Current efforts to boost the capacitance of nanoporous supercapacitors focus on reducing the pore size so that they can only accommodate a single layer of ions. However, this tight packing compromises the charging dynamics and hence power density. We show via an analytical theory and Monte Carlo simulations that charging is sensitively dependent on the affinity of ions to the pores, and that the capacitance of ionophobic pores can be optimized at pore widths significantly larger than the ion diameter. Our theory also predicts that charging can be hysteretic with a significant energy loss per cycle for intermediate ionophilicities. We use these observations to explore the parameter regimes in which a capacitance-power-hysteresis \\emph{trilemma} may...

  16. The Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors

    E-print Network

    Alpha A Lee; Dominic Vella; Alain Goriely; Svyatoslav Kondrat

    2015-10-19

    Nanoporous supercapacitors are an important player in the field of energy storage that fill the gap between dielectric capacitors and batteries. The key challenge in the development of supercapacitors is the perceived tradeoff between capacitance and power delivery. Current efforts to boost the capacitance of nanoporous supercapacitors focus on reducing the pore size so that they can only accommodate a single layer of ions. However, this tight packing compromises the charging dynamics and hence power density. We show via an analytical theory and Monte Carlo simulations that charging is sensitively dependent on the affinity of ions to the pores, and that the capacitance of ionophobic pores can be optimized at pore widths significantly larger than the ion diameter. Our theory also predicts that charging can be hysteretic with a significant energy loss per cycle for intermediate ionophilicities. We use these observations to explore the parameter regimes in which a capacitance-power-hysteresis \\emph{trilemma} may be avoided.

  17. Bistability threshold inside hysteresis loop of nonlinear fiber Bragg gratings.

    PubMed

    Yosia, Yosia; Ping, Shum; Chao, Lu

    2005-06-27

    We show the Cross Phase Modulation (XPM) effect between CW probe that operates in bistability region and strong Gaussian pump in a Fiber Bragg Grating (FBG) by Implicit 4th Order Runge-Kutta Method. The XPM effect results in three unique nonlinear switching behaviors of the probe transmission depending on the pump peak intensity and its Full Width Half Maximum (FWHM) value. From this observation, we offer the FBG three potential nonlinear switching applications in all-optical signal processing domain as: a step-up all-optical switching, an all-optical inverter, and an all-optical limiter. The bistability threshold that determines the nonlinear switching behaviors of probe transmission after Gaussian pump injection is defined numerically and shown to be equivalent to the unstable state inside hysteresis loop. PMID:19498502

  18. Quantification of Hysteresis and Nonlinear Effects on the Frequency Response of Ferroelectric and

    E-print Network

    Quantification of Hysteresis and Nonlinear Effects on the Frequency Response of Ferroelectric. However, these materials also exhibit hysteresis and constitutive nonlinearities at all drive levels of hysteresis and nonlinearities on the frequency behavior of devices that employ these compounds. Whereas

  19. APPLICATION OF AN INVERSE-HYSTERESIS ITERATIVE CONTROL ALGORITHM FOR AFM FABRICATION

    E-print Network

    Leang, Kam K.

    APPLICATION OF AN INVERSE-HYSTERESIS ITERATIVE CONTROL ALGORITHM FOR AFM FABRICATION A thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2 Atomic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3 Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Chapter 3 Iterative Control for Hysteresis Compensation 35 3.1 Motivation

  20. Aalborg Universitet Behavior Patterns, Origin of Problems and Solutions Regarding Hysteresis

    E-print Network

    Berning, Torsten

    Aalborg Universitet Behavior Patterns, Origin of Problems and Solutions Regarding Hysteresis-Irina; Swierczynski, Maciej Jozef; Andreasen, Søren Juhl; Kær, Søren Knudsen Published in: Hysteresis: Types). Behavior Patterns, Origin of Problems and Solutions Regarding Hysteresis Phenomena in Complex Battery

  1. Phase transition and hysteresis in an ensemble of stochastic spiking neurons

    E-print Network

    Gómez, Vicenç

    Phase transition and hysteresis in an ensemble of stochastic spiking neurons Andreas Kaltenbrunner1 by a hysteresis around a critical coupling strength. Below the critical coupling production of spikes coupled oscillators. Keywords: phase transition; hysteresis; stochastic neurons; pulse coupled oscillators

  2. Friction and Adhesion Hysteresis between Surfactant Monolayers in Water

    E-print Network

    Klein, Jacob

    Friction and Adhesion Hysteresis between Surfactant Monolayers in Water Wuge H. Briscoe Physical friction between two surfaces in adhesive contact with the loading­unloading adhesion hysteresis between them. We then examine in light of this model the observed low friction between two mica surfaces coated

  3. Application of the Preisach model in soil-moisture hysteresis

    E-print Network

    Schellekens, Michel P.

    Application of the Preisach model in soil-moisture hysteresis Denis Flynn, Hugh McNamara, Philip O- teresis effects in the relation between water retention and soil-moisture ten- sion. Special, one parameter, classes of Preisach operators are proposed to construct models of the soil-moisture hysteresis

  4. Circuit measures hysteresis loop areas at 30 Hz

    NASA Technical Reports Server (NTRS)

    Hoffman, C.; Spilo, D.

    1967-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  6. Dynamic hysteresis control of lift on a pitching wing

    NASA Astrophysics Data System (ADS)

    Williams, David R.; An, Xuanhong; Iliev, Simeon; King, Rudibert; Reißner, Florian

    2015-05-01

    Dynamic hysteresis appearing in the lift force during pitching maneuvers is distinctly different from conventional static hysteresis. The size and shape of dynamic hysteresis loops are dependent on the degree of flow attachment, the dimensionless pitching frequency, and two time delays associated with the flow separation process. A linearized version of the Goman-Khrabrov model is derived and shown to capture the dynamic hysteresis characteristics when the pitching amplitude is small. Closed-loop control using a linearized version of the Goman-Khrabrov model is demonstrated, which incorporates a disturbance model into the feed-forward controller. The controller is shown to reduce the dynamic hysteresis during periodic pitching, step-up and step-down maneuvers, and quasi-random pitching maneuvers.

  7. Hysteresis of misaligned hard-soft grains

    NASA Astrophysics Data System (ADS)

    Wan, X. L.; Zhao, G. P.; Zhang, X. F.; Xia, J.; Zhang, X. C.; Morvan, F. J.

    2016-01-01

    The demagnetization process in hard/soft multilayer systems has been investigated systematically within a self-contained micromagnetic model when a deviation angle ? between the easy axis and the applied field exists. Hysteresis loops, spin distributions and energy products have been calculated with a finite hard layer thickness th. Both remanence and coercivity of the multilayer system decrease as ? increases, leading to a significant decrease of the maximum energy product. A 30° deviation of the easy axis could result in a drop of the maximum energy product by more than 60%, which offers a possible explanation on the large discrepancy between the experimental and theoretical energy products. The effect of the finite hard layer thickness on the demagnetization process is important, which can only be ignored when th is large enough.

  8. Thermal hysteresis behaviors of thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Iwasaki, Hideo

    2014-12-01

    Thermoelectric behaviors for the thermal cycles between room and high temperatures are investigated in (Bi,Sb)2Te3 and Bi2S3. Because the reliability and reproducibility of the data against repeated heating are required, the Harman method is adopted to evaluate the figure of merit, ZT, in which only electrical contacts are needed. The electrical contacts are made by the spot welding method using a simple and low-power machine made in our laboratory to avoid damage to the samples. Thermoelectric properties are changed by repeating thermal cycles, though their rate of change is not always very high and is material dependent. The carrier number dominantly contributes to the thermal hysteresis of the thermoelectric properties upon the repetition of the thermal cycles, which actually affects the sample as an annealing effect. It is pointed out that changes in thermoelectric properties upon the repetition of the thermal cycles should be examined beforehand in practical applications.

  9. Windmill speed limiting system utilizing hysteresis

    SciTech Connect

    Barnes, D.R.

    1983-02-22

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

  10. A Hysteresis Model for Piezoceramic Materials

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.; Ounaies, Zoubeida

    1999-01-01

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

  11. Pore-scale mechanisms for hysteresis in capillary-dominated drainage and imbibition (Invited)

    NASA Astrophysics Data System (ADS)

    Sheppard, A.; Wildenschild, D.; Andersson, L.; Herring, A. L.

    2013-12-01

    Understanding the flow of two immiscible fluid phases through the pore space of rocks and soils is a complex problem involving fluid dynamics, surface science and geometry. Invariably one fluid, usually water, preferentially coats the solid surface. Of major interest, and a significant challenge for multiphase fluid modelling, is the fact that the flow displays hysteresis: the measured difference in pressure between fluids (the capillary pressure) is higher when the water is draining out than when it is imbibing back in. One consequence of this hysteresis include capillary trapping, of relevance to waterflooding oil recovery and geosequestration of CO¬2. While several models have attempted with mixed success to capture this hysteresis at the macro-scale, no consensus yet exists on its pore-scale causes. The current work makes use of X-ray micro-tomography (MCT) data to help identify resolve this question. We first enumerate the different mechanisms that have been proposed in the literature for this hysteresis. We break these mechanisms into two categories: local mechanisms that may occur inside a single geometric feature (such as a pore or throat) and those that may only be observed within some sort of labyrinth. Local mechanisms include contact angle hysteresis (induced by surface, chemistry surface roughness and/or interface pinning), the ink-bottle effect and geometric bistability associated with the stability of both main terminal menisci and arc menisci in a constrictive pore space element. The nonlocal mechanisms are fluid trapping (possible for both wetting and nonwetting fluids) and structure hysteresis arising from heterogeneity in the pore system. Our results arise from the analysis of imaging experiments in which water was successively imbibed into and drained from small samples of Bentheimer sandstone and unconsolidated grain packs. The experiment were conducted at both synchrotron and laboratory X-ray MCT facilities, with both imaging setups having sufficient resolution to show the distribution of the two fluid phases throughout the material while also capturing fluid menisci in individual pores. We apply a range of topological and geometric analyses to these images, most notably the calculation of Betti numbers, interfacial area and interfacial curvature, to quantify the differences in fluid configurations during imbibition and drainage. While our results suggest that geometric bistability may be the primary cause for hysteresis in these particular experiments, we discuss the significance of our results and suggest that far more work is needed before definitive conclusions can be drawn.

  12. Experimental and simulation of magnetic hysteresis loops of [Co3(pyz)(HPO4)2F2

    NASA Astrophysics Data System (ADS)

    Lee, S. F.; Chang, C. R.; Yang, J. S.; Lii, K. H.; Lee, M. D.; Yao, Y. D.

    2004-06-01

    Pure phase of [Co3(pyz)(HPO4)2F2] crystal powder was successfully synthesized. The structure consisted of neutral sheets of [Co3(HPO4)2F2], which were pillared through pyrazine ligand to form three-dimensional frameworks. Below 20 K, the magnetic hysteresis loops showed a ferromagnetic part superimposed with an antiferromagnetic (AF) part. With increasing field magnitude, the AF part showed sharp steps at 5 kOe. Micromagnetic simulation, taking into account the Co ions as AF coupled sublattices and as suggested by the negative Weiss temperature extrapolated by the inverse susceptibility versus temperature behavior, explained the hysteresis loops the temperature dependence qualitatively.

  13. Understanding the Hysteresis Loop Conundrum in Pharmacokinetic / Pharmacodynamic Relationships

    PubMed Central

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

    2015-01-01

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

  14. Football curves

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

  15. Static measurements of slender delta wing rolling moment hysteresis

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Levin, Daniel

    1991-01-01

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

  16. Electrodynamic soil plate oscillator: Modeling nonlinear mesoscopic elastic behavior and hysteresis in nonlinear acoustic landmine detection

    NASA Astrophysics Data System (ADS)

    Korman, M. S.; Duong, D. V.; Kalsbeck, A. E.

    2015-10-01

    An apparatus (SPO), designed to study flexural vibrations of a soil loaded plate, consists of a thin circular elastic clamped plate (and cylindrical wall) supporting a vertical soil column. A small magnet attached to the center of the plate is driven by a rigid AC coil (located coaxially below the plate) to complete the electrodynamic soil plate oscillator SPO design. The frequency dependent mechanical impedance Zmech (force / particle velocity, at the plate's center) is inversely proportional to the electrical motional impedance Zmot. Measurements of Zmot are made using the complex output to input response of a Wheatstone bridge that has an identical coil element in one of its legs. Near resonance, measurements of Zmot (with no soil) before and after a slight point mass loading at the center help determine effective mass, spring, damping and coupling constant parameters of the system. "Tuning curve" behavior of real{ Zmot } and imaginary{ Zmot } at successively higher vibration amplitudes of dry sifted masonry sand are measured. They exhibit a decrease "softening" in resonance frequency along with a decrease in the quality Q factor. In soil surface vibration measurements a bilinear hysteresis model predicts the tuning curve shape for this nonlinear mesoscopic elastic SPO behavior - which also models the soil vibration over an actual plastic "inert" VS 1.6 buried landmine. Experiments are performed where a buried 1m cube concrete block supports a 12 inch deep by 30 inch by 30 inch concrete soil box for burying a VS 1.6 in dry sifted masonry sand for on-the-mine and off-the-mine soil vibration experiments. The backbone curve (a plot of the peak amplitude vs. corresponding resonant frequency from a family of tuning curves) exhibits mostly linear behavior for "on target" soil surface vibration measurements of the buried VS 1.6 or drum-like mine simulants for relatively low particle velocities of the soil. Backbone curves for "on target" measurements exhibit significant curvature when the soil particle velocity is relatively higher. An oscillator with hysteresis modeled by a distribution of parallel spring elements each with a different threshold slip condition seems to describe fairly linear backbone curve behavior [W. D. Iwan, Transactions of the ASME, J. of Applied Mech., 33,(1966), 893-900], while a single bilinear hysteresis element describes the backbone curvature results in the experiments reported here [T. K. Caughey, Transactions of the ASME, J. of Applied Mech., 27, (1960), 640-643]. When "off target" resonances have a different backbone curvature than "on the mine" backbone curves, then false alarms may be eliminated due to resonances from the natural soil layering. See [R. A. Guyer, J. TenCate, and P. Johnson, "Hysteresis and the Dynamic Elasticity of Consolidated Granular Materials," Phys. Rev. Lett., 82, 16 (1999), 3280-3283] for recent models of nonlinear mesoscopic behavior.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  19. Theory of hysteresis during electron heating of electromagnetic wave scattering by self-organized dust structures in complex plasmas

    NASA Astrophysics Data System (ADS)

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-07-01

    Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.

  20. Hysteresis at low Reynolds number: the onset of 2D vortex shedding

    E-print Network

    V. K. Horvath; J. R. Cressman; W. I. Goldburg; X. L. Wu

    2000-03-21

    Hysteresis has been observed in a study of the transition between laminar flow and vortex shedding in a quasi-two dimensional system. The system is a vertical, rapidly flowing soap film which is penetrated by a rod oriented perpendicular to the film plane. Our experiments show that the transition from laminar flow to a periodic K\\'arm\\'an vortex street can be hysteretic, i.e. vortices can survive at velocities lower than the velocity needed to generate them.

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

    PubMed

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

    2011-06-22

    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

  2. Hysteresis Models of Dynamic Mode Atomic Force Microscopes: Analysis and Identification

    E-print Network

    Michele Basso; Donatello Materassi; Murti V. Salapaka

    2007-10-21

    A new class of models based on hysteresis functions is developed to describe atomic force microscopes operating in dynamic mode. Such models are able to account for dissipative phenomena in the tip-sample interaction which are peculiar of this operation mode. The model analysis, which can be pursued using frequency domain techniques, provides a clear insight of specific nonlinear behaviours. Experiments show good agreement with the identified models.

  3. L1 Adaptive Control of Hysteresis in Smart Materials Xiang Fan and Ralph C. Smith

    E-print Network

    L1 Adaptive Control of Hysteresis in Smart Materials Xiang Fan and Ralph C. Smith Center behavior. Hence these mate- rials have inherent sensing and actuation capacities. However, the hysteresis compensation is a fundamental approach to cope with hysteresis, where one aims to cancel out the hysteresis

  4. Barkhausen Noise Modelling 5.1 Existing models of hysteresis and Barkhausen

    E-print Network

    Cambridge, University of

    Chapter 5 Barkhausen Noise Modelling 5.1 Existing models of hysteresis and Barkhausen noise 5 in magnetostatic energy, or as hysteresis loss. In the absence of hysteresis, all the energy supplied would go be expressed in terms of Man: Esupp = µ0 Man{H}dH (5.4) Hysteresis loss was attributed to domain wall pinning

  5. Bubble dynamics atop an oscillating substrate: Interplay of compressibility and contact angle hysteresis

    E-print Network

    Straube, Arthur V.

    hysteresis Irina S. Fayzrakhmanova,1 Arthur V. Straube,2,3,a) and Sergey Shklyaev3,4 1 Department and the contact angle hysteresis. In the presence of contact angle hysteresis, the compressible bubble exhibits of such factors as compressibility and contact angle hysteresis, by looking at a relatively sim- ple theoretical

  6. A high-speed hysteresis motor spindle for machining applications

    E-print Network

    Bayless, Jacob D. (Jacob Daniel)

    2014-01-01

    An analysis of suitable drive technologies for use in a new high-speed machining spindle was performed to determine critical research areas. The focus is on a hysteresis motor topology using a solid, inherently-balanced ...

  7. Magnetically suspended reaction sphere with one-axis hysteresis drive

    E-print Network

    Zhou, Lei., S.M. Massachusetts Institute of Technology

    2014-01-01

    This thesis presents the design, modeling, implementation, and control of a magnetically suspended reaction sphere with one-axis hysteresis drive (1D-MSRS). The goal of this project is two fold: (a) exploring the design ...

  8. Hysteresis modeling of clamp band joint with macro-slip

    NASA Astrophysics Data System (ADS)

    Qin, Zhaoye; Cui, Delin; Yan, Shaoze; Chu, Fulei

    2016-01-01

    Clamp band joints are commonly used to connect spacecrafts with launch vehicles. Due to the frictional slippage between the joint components, hysteresis behavior might occur at joint interfaces under cyclic loading. The joint hysteresis will bring friction damping into the launching systems. In this paper, a closed-form hysteresis model for the clamp band joint is developed based on theoretical and numerical analyses of the interactions of the joint components. Then, the hysteresis model is applied to investigating the dynamic response of a payload fastened by the clamp band joint, where the nonlinearity and friction damping effects of the joint is evaluated. The proposed analytical model, which is validated by both finite element analyses and quasi-static experiments, has a simple form with sound accuracy and can be incorporated into the dynamic models of launching systems conveniently.

  9. Essays on crime, hysteresis, poverty and conditional cash transfers 

    E-print Network

    Loureiro, Andre Oliveira Ferreira

    2013-07-03

    This thesis encompasses three essays around criminal behaviour with the first one analysing the impact of programmes aimed at poverty reduction, the second one developing a theoretical model of hysteresis in crime, and ...

  10. Contact angle hysteresis: a review of fundamentals and applications

    E-print Network

    ’t Mannetje, D. J. C. M.

    Contact angle hysteresis is an important physical phenomenon. It is omnipresent in nature and also plays a crucial role in various industrial processes. Despite its relevance, there is a lack of consensus on how to incorporate ...

  11. Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes

    NASA Astrophysics Data System (ADS)

    Xu, Jixian; Buin, Andrei; Ip, Alexander H.; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J.; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G.; Maksymovych, Peter; Sargent, Edward H.

    2015-05-01

    Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3- antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.

  12. Dynamic wetting on superhydrophobic surfaces: Droplet impact and wetting hysteresis

    E-print Network

    Smyth, Katherine M.

    We study the wetting energetics and wetting hysteresis of sessile and impacting water droplets on superhydrophobic surfaces as a function of surface texture and surface energy. For sessile drops, we find three wetting ...

  13. Low-Hysteresis Flow-Through Wind-Tunnel Balance

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  14. On the question of hysteresis in Hall magnetohydrodynamic reconnection

    SciTech Connect

    Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin

    2010-11-15

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

  15. Hysteresis in the spectral states of the neutron star low-mass X-ray binary EXO 1745-248

    E-print Network

    Mukherjee, Arunava

    2011-01-01

    We study the low-frequency timing properties and the spectral state evolution of the transient neutron star low-mass X-ray binary EXO 1745-248 using the entire Rossi X-ray Timing Explorer Proportional Counter Array data. We tentatively conclude that EXO 1745-248 is an atoll source, and report the discovery of a ~ 0.45 Hz low-frequency quasi-periodic oscillation and ~ 10 Hz peaked noises. If it is an atoll, this source is unusual because (1) instead of a `C'-like curve, it traced a clear overall clockwise hysteresis curve in each of the colour-colour diagram and the hardness-intensity diagram; and (2) the source took at least 2.5 months to trace the softer banana state, as opposed to a few hours to a day, which is typical for an atoll source. The shape of the hysteresis track was intermediate between the characteristic `q'-like curves of several black hole systems and `C'-like curves of atolls, implying that EXO 1745-248 is an important source for the unification of the black hole and neutron star accretion pr...

  16. High hysteresis in a homogeneous metallic glass

    NASA Astrophysics Data System (ADS)

    Branagan, D. J.; Meacham, B. E.; McCallum, R. W.; Dennis, K. W.; Kramer, M. J.

    2003-05-01

    In this article, we demonstrate high hysteresis in a well characterized homogeneous Tb-Al glass which contained no crystallites or crystalline embryos as verified using conventional and synchrotron diffraction, neutron diffraction, and direct observation in the transmission electron microscope. At low temperature (2 K), the metallic glass structure exhibited intrinsic coercivities approaching 23 kOe and high isotropic energy products of 12.4 MGOe. After crystallization into a three-phase nanoscale structure, the hard magnetic properties were found to be far inferior to that obtainable in the glass structure. From the well defined intrinsic magnetic properties (Msat,Tc), it is clear that the glass contains one or more types of well defined associations (i.e., clusters) and that these associations lead to ferromagnetic coupling/ordering. From the large random magnetic anisotropy, it is probable that the domain size is much larger than the structural cluster size. The measured single-phase loop shapes and the development of high coercivity in the glass state can be explained by an "exchange bias" mechanism resulting in a near perfect distribution of "fragile" pinning centers.

  17. Hysteresis and transition in swirling nonpremixed flames

    SciTech Connect

    Tummers, M.J.; Huebner, A.W.; van Veen, E.H.; Hanjalic, K.; van der Meer, T.H.

    2009-02-15

    Strongly swirling nonpremixed flames are known to exhibit a hysteresis when transiting from an attached long, sooty, yellow flame to a short lifted blue flame, and vice versa. The upward transition (by increasing the air and fuel flow rates) corresponds to a vortex breakdown, i.e. an abrupt change from an attached swirling flame (unidirectional or with a weak bluff-body recirculation), to a lifted flame with a strong toroidal vortex occupying the bulk of the flame. Despite dramatic differences in their structures, mixing intensities and combustion performance, both flame types can be realised at identical flow rates, equivalence ratio and swirl intensity. We report here on comprehensive investigations of the two flame regimes at the same conditions in a well-controlled experiment in which the swirl was generated by the rotating outer pipe of the annular burner air passage. Fluid velocity measured with PIV (particle image velocimetry), the qualitative detection of reaction zones from OH PLIF (planar laser-induced fluorescence) and the temperature measured by CARS (coherent anti-Stokes Raman spectroscopy) revealed major differences in vortical structures, turbulence, mixing and reaction intensities in the two flames. We discuss the transition mechanism and arguments for the improved mixing, compact size and a broader stability range of the blue flame in comparison to the long yellow flame. (author)

  18. Experiments on sorption hysteresis of desiccant materials

    SciTech Connect

    Pesaran, A.; Zangrando, F.

    1984-08-01

    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.

  19. The Effect of Tensile Hysteresis and Contact Resistance on the Performance of Strain-Resistant Elastic-Conductive Webbing

    PubMed Central

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

    2011-01-01

    To use e-textiles as a strain-resistance sensor they need to be both elastic and conductive. Three kinds of elastic-conductive webbings, including flat, tubular, and belt webbings, made of Lycra fiber and carbon coated polyamide fiber, were used in this study. The strain-resistance properties of the webbings were evaluated in stretch-recovery tests and measured within 30% strain. It was found that tensile hysteresis and contact resistance significantly influence the tensile elasticity and the resistance sensitivity of the webbings. The results showed that the webbing structure definitely contributes to the tensile hysteresis and contact resistance. The smaller the friction is among the yarns in the belt webbing, the smaller the tensile hysteresis loss. However the close proximity of the conductive yarns in flat and tubular webbings results in a lower contact resistance. PMID:22319376

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  1. The effect of tensile hysteresis and contact resistance on the performance of strain-resistant elastic-conductive webbing.

    PubMed

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

    2011-01-01

    To use e-textiles as a strain-resistance sensor they need to be both elastic and conductive. Three kinds of elastic-conductive webbings, including flat, tubular, and belt webbings, made of Lycra fiber and carbon coated polyamide fiber, were used in this study. The strain-resistance properties of the webbings were evaluated in stretch-recovery tests and measured within 30% strain. It was found that tensile hysteresis and contact resistance significantly influence the tensile elasticity and the resistance sensitivity of the webbings. The results showed that the webbing structure definitely contributes to the tensile hysteresis and contact resistance. The smaller the friction is among the yarns in the belt webbing, the smaller the tensile hysteresis loss. However the close proximity of the conductive yarns in flat and tubular webbings results in a lower contact resistance. PMID:22319376

  2. Hysteresis in the tearing mode locking/unlocking due to resonant magnetic perturbations in EXTRAP T2R

    NASA Astrophysics Data System (ADS)

    Fridström, R.; Frassinetti, L.; Brunsell, P. R.

    2015-10-01

    The physical mechanisms behind the hysteresis in the tearing mode locking and unlocking to a resonant magnetic perturbation (RMP) are experimentally studied in EXTRAP T2R reversed-field pinch. The experiments show that the electromagnetic and the viscous torque increase with increasing perturbation amplitude until the mode locks to the wall. At the wall-locking, the plasma velocity reduction profile is peaked at the radius where the RMP is resonant. Thereafter, the viscous torque drops due to the relaxation of the velocity in the central plasma. This is the main reason for the hysteresis in the RMP locking and unlocking amplitude. The increased amplitude of the locked tearing mode produces further deepening of the hysteresis. Both experimental results are in qualitative agreement with the model in Fitzpatrick et al (2001 Phys. Plasmas 8 4489)

  3. Throwing a Curve

    E-print Network

    Wedge, Philip

    2000-09-01

    134 Aethlon XVIII: 1 / Fall 2000 Throwing A Curve Coming home from Roy's team picture, we stop to show off the brand-new uniform - Blue Jays stenciled on the front, stockings, the works. Out of mischief or shyness hes at the edge of the room...134 Aethlon XVIII: 1 / Fall 2000 Throwing A Curve Coming home from Roy's team picture, we stop to show off the brand-new uniform - Blue Jays stenciled on the front, stockings, the works. Out of mischief or shyness hes at the edge of the room...

  4. Changes in surface figure due to thermal hysteresis

    NASA Astrophysics Data System (ADS)

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

    1987-01-01

    Thermal cycling hysteresis affects surface figure in low-expansivity mirror substrates. Zerodur, ULE, and Cer-Vit 8-in.-diameter mirrors and dilatometer samples were thermally cycled at uniform rates of 6 K/hr and 60 K/hr, and somewhat faster for nonuniform heating. Figure distortions as large as lambda/10 were observed following nonuniform heating of standard Zerodur, which was the only material exhibiting thermal hysteresis. A new experimental Zerodur appears to be free of this problem.

  5. Chaos-induced dynamical hysteresis: Energetic and entropic barriers

    NASA Astrophysics Data System (ADS)

    Das, Moupriya; Ray, Deb Shankar

    2013-03-01

    We consider periodically driven dynamical systems with energetic and entropic barriers in the presence of deterministic noise. Due to the relaxational delay, the response of the system lags behind the applied field and exhibits dynamical hysteresis manifested in the nonvanishing area of the response-function-field loop. It is demonstrated that the hysteresis loop area satisfies a scaling law with exponents that depend on the nature of the barrier.

  6. Stabilization of supercooled fluids by thermal hysteresis proteins.

    PubMed Central

    Wilson, P W; Leader, J P

    1995-01-01

    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. PMID:7612853

  7. Aileron roll hysteresis effects on entry of space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Powell, R. W.

    1977-01-01

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

  8. A Jiles-Atherton and fixed-point combined technique for time periodic magnetic field problems with hysteresis

    SciTech Connect

    Chiampi, M.; Repetto, M.; Chiarabaglio, D.

    1995-11-01

    The hysteresis phenomenon can significantly affect the behavior of magnetic cores in electrical machines and devices. This paper presents a finite element solution of periodic steady state magnetic field problems in soft materials with scalar hysteresis. The Jiles-Atherton model is employed for the generation of symmetric B-H loops and it is coupled with the Fixed Point Technique for handling magnetic nonlinearities. The proposed procedure is applied to a hysteretic model problem whose analytical solution is available. The results show that the Fixed Point Technique can efficiently deal with non-single valued material characteristics under periodic operating conditions.

  9. Adhesion hysteresis and friction at nanometer and micrometer lengths

    SciTech Connect

    Szoszkiewicz, Robert; Bhushan, Bharat; Huey, Bryan D.; Kulik, Andrzej J.; Gremaud, Gerard

    2006-01-01

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

  10. Voltage control of magnetic hysteresis in a nickel nanoparticle

    NASA Astrophysics Data System (ADS)

    Gartland, P.; Jiang, W.; Davidovi?, D.

    2015-06-01

    The effects of voltage bias on magnetic hysteresis in single Ni particles 2 to 3 nm in diameter are measured between temperatures of 60 mK and 4.2 K by using sequential electron tunneling through the particle. While some Ni particles do not display magnetic hysteresis in tunneling current versus magnetic field, in the Ni particles that display hysteresis, the effect of bias voltage on magnetic switching field is nonlinear. The magnetic switching field changes weakly in the voltage interval ˜1 mV above the tunneling onset voltage, and rapidly decreases versus voltage above that interval. A voltage-driven mechanism explaining this nonlinear suppression of magnetic hysteresis is presented, where the key effect is a magnetization blockade due to the addition of spin-orbit anisotropy ?so to the particle by a single electron. A necessary condition for the particle to exhibit magnetization blockade is that ?so increases when the magnetization is slightly displaced from the easy axis. In that case, an electron will be energetically unable to access the particle if the magnetization is sufficiently displaced from the easy axis, which leads to a voltage interval where magnetic hysteresis is possible that is comparable to ?so/e , where e is the electronic charge. If ?so decreases vs magnetization displacement from the easy axis, there is no magnetization blockade and no hysteresis.

  11. The extremely narrow hysteresis width of phase transition in nanocrystalline VO2 thin films with the flake grain structures

    NASA Astrophysics Data System (ADS)

    Xu, Xiaofeng; He, Xinfeng; Wang, Haiyang; Gu, Quanju; Shi, Shuaixu; Xing, Huaizhong; Wang, Chunrui; Zhang, Jing; Chen, Xiaoshuang; Chu, Junhao

    2012-11-01

    The nanocrystalline VO2 thin films, which surface has a flake grain structure, are achieved by DC sputtering deposition at different sputtering powers. It is found that the hysteresis loop of metal-insulator phase transition (MIT) is almost superposition, and the hysteresis width is only 0.4 °C for the surface flake grain structure that obtained at 132 W DC sputtering power. Moreover, it is shown that the phase transition is very steep, and the film displays 3-4 orders of the change of sheet resistance at MIT. The characterizations of SEM, AFM and four-point probe methods show that the hysteresis width, the orders of the change of sheet resistance and the phase transition become narrower, higher and steeper at MIT, respectively when the surface shapes of the nanocrystalline VO2 thin films change from nanoparticle structures to flake structures with the DC sputtering powers increased from 66 W to 132 W and the surface flake grain sizes reduced gradually to minimum at 132 W. Meanwhile, the surface roughness also changes into minimum. However, with the powers further increased from 132 W to 176 W, the surface flake grain sizes become bigger, and then the surface roughness changes poor. At 176 W, the surface flake structures begin to turn into nanoparticle structures. The hysteresis width, the orders of the change of sheet resistance and the phase transition become wider, lower and poorly steeper at MIT, separately. The results reveal that the nanocrystalline shapes and the surface roughness can affect the hysteresis width and the sheet resistance steepness in MIT. Our analysis shows that the mechanism of the narrowed hysteresis width mainly depends on the strain imbalance of the nanocrystalline VO2 thin film of the flake structures at MIT.

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

    SciTech Connect

    Zhang Lefu; Takahashi, Seiki; Kamada, Yasuhiro; Kikuchi, Hiroaki; Mumtaz, Khalid; Ara, Katsuyuki; Sato, Masaya

    2005-04-09

    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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Lefu; Takahashi, Seiki; Kamada, Yasuhiro; Kikuchi, Hiroaki; Mumtaz, Khalid; Ara, Katsuyuki; Sato, Masaya

    2005-04-01

    Magnetic method has been used to evaluate the volume percentage of ?' 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 ?' 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 ?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 ?' martensitic phase in stainless steels.

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

    NASA Astrophysics Data System (ADS)

    Ekkachai, Kittipong; Tungpimolrut, Kanokvate; Nilkhamhang, Itthisek

    2013-11-01

    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.

  15. Hysteresis of the metal-insulator transition of ? evidence of the influence of microscopic texturation

    NASA Astrophysics Data System (ADS)

    Petit, Christophe; Frigerio, Jean-Marc; Goldmann, Michel

    1999-04-01

    Vanadium dioxide films have been deposited on silicon substrates by reactive RF cathodic sputtering from 0953-8984/11/16/007/img7 and 0953-8984/11/16/007/img8 targets. The optical measurements show a good contrast at the semiconductor-metal transition, but exhibit two kinds of hysteresis cycle: a narrow and symmetrical one, and a wider and asymmetrical one. We have mainly studied the microstructure of these samples by means of grazing-incidence x-ray diffraction at the LURE synchrotron radiation facility. We analysed in detail the intensities of the diffraction peak spectra and of the portions of diffraction rings. We found a clear relation between a narrow and symmetrical hysteresis cycle, and a (011) texture of the films. We attribute this result to an improvement in the cooperativity of the transition phenomena.

  16. Stability of shock wave reflections in nonequilibrium steady flows and hysteresis

    NASA Astrophysics Data System (ADS)

    Grasso, F.; Paoli, R.

    2000-12-01

    In the present work we have addressed the issue of the stability of shock wave reflection in the presence of vibrational and chemical relaxation phenomena and its relation with the occurrence of the hysteresis. In order to better understand the physics of the shock wave reflections we have first formulated an evolution equation for the entropy of a mixture of gases in thermal and chemical nonequilibrium by invoking the shifting equilibrium assumption and the concepts of irreversible thermodynamics, and assuming (i) that all diatomic molecules behave as harmonic oscillators; and (ii) finite rate chemistry. A perturbation analysis of the total entropy evolution equation has then been carried out to analyze the stability of shock wave configurations (either regular or Mach) both for ideal and real gases. The analysis shows that a Mach reflection is more stable than a regular one; furthermore, its stability is enhanced by nonequilibrium effects. In order to clarify the occurrence of the hysteresis phenomenon in light of the conclusions reached through the stability analysis, we have also carried out multidimensional simulations (both at flight and wind tunnel conditions) by developing a pseudotransient procedure to span a (hysteresis) loop dual solution domain ? Mach reflection domain ? dual solution domain. The simulations show that the total entropy of the system exhibits an abrupt change along the path dual solution domain ? Mach reflection domain, while it is continuous along the reverse path. An argument is then developed to prove that hysteresis is the natural consequence of the different stability properties of regular and Mach reflections and the Prigogine minimum total entropy production principle.

  17. Dual-domain mass-transfer parameters from electrical hysteresis: theory and analytical approach applied to laboratory, synthetic streambed, and groundwater experiments

    USGS Publications Warehouse

    Briggs, Martin; Day-Lewis, Frederick D.; Ong, John B.; Harvey, Judson W.; Lane, John W.

    2014-01-01

    Models of dual-domain mass transfer (DDMT) are used to explain anomalous aquifer transport behavior such as the slow release of contamination and solute tracer tailing. Traditional tracer experiments to characterize DDMT are performed at the flow path scale (meters), which inherently incorporates heterogeneous exchange processes; hence, estimated “effective” parameters are sensitive to experimental design (i.e., duration and injection velocity). Recently, electrical geophysical methods have been used to aid in the inference of DDMT parameters because, unlike traditional fluid sampling, electrical methods can directly sense less-mobile solute dynamics and can target specific points along subsurface flow paths. Here we propose an analytical framework for graphical parameter inference based on a simple petrophysical model explaining the hysteretic relation between measurements of bulk and fluid conductivity arising in the presence of DDMT at the local scale. Analysis is graphical and involves visual inspection of hysteresis patterns to (1) determine the size of paired mobile and less-mobile porosities and (2) identify the exchange rate coefficient through simple curve fitting. We demonstrate the approach using laboratory column experimental data, synthetic streambed experimental data, and field tracer-test data. Results from the analytical approach compare favorably with results from calibration of numerical models and also independent measurements of mobile and less-mobile porosity. We show that localized electrical hysteresis patterns resulting from diffusive exchange are independent of injection velocity, indicating that repeatable parameters can be extracted under varied experimental designs, and these parameters represent the true intrinsic properties of specific volumes of porous media of aquifers and hyporheic zones.

  18. Coexistence of phase transitions and hysteresis near BEC

    E-print Network

    M. Männel; K. Morawetz; P. Lipavský

    2013-05-22

    Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC) the chemical potential and the pressure show a van-der-Waals like behavior indicating a first-order phase transition although there is no long-range attraction. Furthermore the equation of state becomes multivalued near the BEC transition. For a Hartree-Fock or Popov (Hartree-Fock-Bogoliubov) approximation such a multivalued region can be avoided by the Maxwell construction. For sufficiently weak interaction the multivalued region can also be removed using a many-body \\mbox{T-matrix} approximation. However, for strong interactions there remains a multivalued region even for the \\mbox{T-matrix} approximation and after the Maxwell construction, what is interpreted as a density hysteresis. This unified treatment of normal and condensed phases becomes possible due to the recently found scheme to eliminate self-interaction in the \\mbox{T-matrix} approximation, which allows to calculate properties below and above the critical temperature.

  19. Hysteresis analysis and positioning control for a magnetic shape memory actuator.

    PubMed

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2015-01-01

    Magnetic shape memory alloys (MSM alloys), a new kind of smart materials, have become a potential candidate in many engineering fields. MSMs have the advantage of bearing a huge strain, much larger than other materials. In addition, they also have fast response. These characteristics make MSM a good choice in micro engineering. However, MSMs display the obvious hysteresis phenomenon of nonlinear behavior. Thus the difficulty in using the MSM element as a positioning actuator is increased due to the hysteresis. In this paper, the hysteresis phenomenon of the MSM actuator is analyzed, and the closed-loop positioning control is also implemented experimentally. For that, a modified fuzzy sliding mode control (MFSMC) is proposed. The MFSMC and the PID control are used to design the controllers for realizing the positioning control. The experimental results are compared under different experimental conditions, such as different frequency, amplitude, and loading. The experimental results show that the precise positioning control of MFSMC can be achieved satisfactorily. PMID:25853405

  20. Hysteresis properties of ordinary chondrites and implications for their thermal history

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    We present a large dataset of magnetic hysteresis properties of ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite and tetrataenite (both in the cloudy zone and as larger grains in plessite and in the rim of zoned taenite). Kamacite dominates the induced magnetism whereas tetrataenite dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. Type 5 and 6 chondrites have higher tetrataenite content than type 4 chondrites, suggesting they have lower cooling rates at least in the 650-450 °C interval, consistent with an onion-shell model. In equilibrated chondrites, shock-related transient heating events above ~500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism, and high cooling rates following shock reheating or excavation after thermal metamorphism.

  1. Design of a MEMS piezoresistive differential pressure sensor with small thermal hysteresis for air data modules.

    PubMed

    Song, Jin Woo; Lee, Jang-Sub; An, Jun-Eon; Park, Chan Gook

    2015-06-01

    The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process. PMID:26133864

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

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

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

  3. Disordered self assembled monolayer dielectric induced hysteresis in organic field effect transistors.

    PubMed

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

    2014-06-01

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

  4. Nonequilibrium hysteresis and Wien effect water dissociation at a bipolar membrane

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  5. Hysteresis Analysis and Positioning Control for a Magnetic Shape Memory Actuator

    PubMed Central

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2015-01-01

    Magnetic shape memory alloys (MSM alloys), a new kind of smart materials, have become a potential candidate in many engineering fields. MSMs have the advantage of bearing a huge strain, much larger than other materials. In addition, they also have fast response. These characteristics make MSM a good choice in micro engineering. However, MSMs display the obvious hysteresis phenomenon of nonlinear behavior. Thus the difficulty in using the MSM element as a positioning actuator is increased due to the hysteresis. In this paper, the hysteresis phenomenon of the MSM actuator is analyzed, and the closed-loop positioning control is also implemented experimentally. For that, a modified fuzzy sliding mode control (MFSMC) is proposed. The MFSMC and the PID control are used to design the controllers for realizing the positioning control. The experimental results are compared under different experimental conditions, such as different frequency, amplitude, and loading. The experimental results show that the precise positioning control of MFSMC can be achieved satisfactorily. PMID:25853405

  6. Design of a MEMS piezoresistive differential pressure sensor with small thermal hysteresis for air data modules

    NASA Astrophysics Data System (ADS)

    Song, Jin Woo; Lee, Jang-Sub; An, Jun-Eon; Park, Chan Gook

    2015-06-01

    The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process.

  7. The hysteresis response of soil CO2 concentration and soil respiration to soil temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Quan; Katul, Gabriel G.; Oren, Ram; Daly, Edoardo; Manzoni, Stefano; Yang, Dawen

    2015-08-01

    Diurnal hysteresis between soil temperature (Ts) and both CO2 concentration ([CO2]) and soil respiration rate (Rs) were reported across different field experiments. However, the causes of these hysteresis patterns remain a subject of debate, with biotic and abiotic factors both invoked as explanations. To address these issues, a CO2 gas transport model is developed by combining a layer-wise mass conservation equation for subsurface gas phase CO2, Fickian diffusion for gas transfer, and a CO2 source term that depends on soil temperature, moisture, and photosynthetic rate. Using this model, a hierarchy of numerical experiments were employed to disentangle the causes of the hysteretic [CO2]-Ts and CO2 flux Ts (i.e., F-Ts) relations. Model results show that gas transport alone can introduce both [CO2]-Ts and F-Ts hystereses and also confirm prior findings that heat flow in soils lead to [CO2] and F being out of phase with Ts, thereby providing another reason for the occurrence of both hystereses. The area (Ahys) of the [CO2]-Ts hysteresis near the surface increases, while the Ahys of the Rs-Ts hysteresis decreases as soils become wetter. Moreover, a time-lagged carbon input from photosynthesis deformed the [CO2]-Ts and Rs-Ts patterns, causing a change in the loop direction from counterclockwise to clockwise with decreasing time lag. An asymmetric 8-shaped pattern emerged as the transition state between the two loop directions. Tracing the pattern and direction of the hysteretic [CO2]-Ts and Rs-Ts relations can provide new ways to fingerprint the effects of photosynthesis stimulation on soil microbial activity and detect time lags between rhizospheric respiration and photosynthesis.

  8. Transport along Null Curves

    E-print Network

    Joseph Samuel; Rajaram Nityananda

    2000-05-22

    Fermi Transport is useful for describing the behaviour of spins or gyroscopes following non-geodesic, timelike world lines. However, Fermi Transport breaks down for null world lines. We introduce a transport law for polarisation vectors along non-geodesic null curves. We show how this law emerges naturally from the geometry of null directions by comparing polarisation vectors associated with two distinct null directions. We then give a spinorial treatment of this topic and make contact with the geometric phase of quantum mechanics. There are two significant differences between the null and timelike cases. In the null case (i) The transport law does not approach a unique smooth limit as the null curve approaches a null geodesic. (ii) The transport law for vectors is integrable, i.e the result depends only on the local properties of the curve and not on the entire path taken. However, the transport of spinors is not integrable: there is a global sign of topological origin.

  9. PREFACE: International Workshop on Multi-Rate Processes and Hysteresis

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

  10. A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space

    NASA Astrophysics Data System (ADS)

    Cihan, Abdullah; Birkholzer, Jens; Illangasekare, Tissa H.; Zhou, Quanlin

    2014-01-01

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

  11. Evaluation of the potential for hysteresis in index-velocity ratings for the Chicago Sanitary and Ship Canal near Lemont, Illinois

    USGS Publications Warehouse

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

    2013-01-01

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

  12. Memory characteristics of hysteresis and creep in multi-layer piezoelectric actuators: An experimental analysis

    NASA Astrophysics Data System (ADS)

    Biggio, Matteo; Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro; Storace, Marco

    2014-02-01

    In this paper we provide an experimental characterization of creep and hysteresis in a multi-layer piezoelectric actuator (PEA), taking into account their relationships in terms of memory structure. We fit the well-known log-t model to the response of the PEA when driven by piecewise-constant signals, and find that both the instantaneous and the delayed response of the PEA display hysteretic dependence on the voltage level. We investigate experimentally the dependence of the creep coefficient on the input history, by driving the PEA along first-order reversal curves and congruent minor loops, and find that it displays peculiar features like strict congruence of the minor loops and discontinuities. We finally explain the observed experimental behaviors in terms of a slow relaxation of the staircase interface line in the Preisach plane.

  13. Capacitive Dark Currents, Hysteresis, and Electrode Polarization in Lead Halide Perovskite Solar Cells.

    PubMed

    Almora, Osbel; Zarazua, Isaac; Mas-Marza, Elena; Mora-Sero, Ivan; Bisquert, Juan; Garcia-Belmonte, Germà

    2015-05-01

    Despite spectacular advances in conversion efficiency of perovskite solar cell many aspects of its operating modes are still poorly understood. Capacitance constitutes a key parameter to explore which mechanisms control particular functioning and undesired effects as current hysteresis. Analyzing capacitive responses allows addressing not only the nature of charge distribution in the device but also the kinetics of the charging processes and how they alter the solar cell current. Two main polarization processes are identified. Dielectric properties of the microscopic dipolar units through the orthorhombic-to-tetragonal phase transition account for the measured intermediate frequency capacitance. Electrode polarization caused by interfacial effects, presumably related to kinetically slow ions piled up in the vicinity of the outer interfaces, consistently explain the reported excess capacitance values at low frequencies. In addition, current-voltage curves and capacitive responses of perovskite-based solar cells are connected. The observed hysteretic effect in the dark current originates from the slow capacitive mechanisms. PMID:26263328

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

    SciTech Connect

    Gao Fei; Zhao Shuxia; Li Xiaosong; Wang Younian

    2010-10-15

    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.

  15. Nonlinear space charge dynamics in mixed ionic-electronic conductors: Resistive switching and ferroelectric-like hysteresis of electromechanical response

    SciTech Connect

    Morozovska, Anna N.; Morozovsky, Nicholas V.; Eliseev, Eugene A.; Varenyk, Olexandr V.; Kim, Yunseok; Strelcov, Evgheni; Tselev, Alexander; Kalinin, Sergei V.

    2014-08-14

    We performed self-consistent modelling of nonlinear electrotransport and electromechanical response of thin films of mixed ionic-electronic conductors (MIEC) allowing for steric effects of mobile charged defects (ions, protons, or vacancies), electron degeneration, and Vegard stresses. We establish correlations between the features of the nonlinear space-charge dynamics, current-voltage, and bending-voltage curves for different types of the film electrodes. A pronounced ferroelectric-like hysteresis of the bending-voltage loops and current maxima on the double hysteresis current-voltage loops appear for the electron-transport electrodes. The double hysteresis loop with pronounced humps indicates a memristor-type resistive switching. The switching occurs due to the strong nonlinear coupling between the electronic and ionic subsystems. A sharp meta-stable maximum of the electron density appears near one open electrode and moves to another one during the periodic change of applied voltage. Our results can explain the nonlinear nature and correlation of electrical and mechanical memory effects in thin MIEC films. The analytical expression proving that the electrically induced bending of MIEC films can be detected by interferometric methods is derived.

  16. Contact Hysteresis and Friction of Alkanethiol SAMs on Au

    SciTech Connect

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

    1998-10-14

    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.

  17. Hysteresis of Freedericksz transition in confined light beams

    SciTech Connect

    Ledney, M. F. Tarnavsky, A. S.

    2010-03-15

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

  18. Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators

    NASA Technical Reports Server (NTRS)

    Smith, R. C.

    1997-01-01

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

  19. An Energy-Based Hysteresis Model for Magnetostrictive Transducers

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  20. Sinusoidal input describing function for hysteresis followed by elementary backlash

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.

    1976-01-01

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

  1. Ventilation above closing volume reduces pulmonary vascular resistance hysteresis.

    PubMed

    Creamer, K M; McCloud, L L; Fisher, L E; Ehrhart, I C

    1998-10-01

    The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hysteresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood-perfused canine left lower lung lobes (LLL) were incrementally inflated and deflated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant blood flow was provided (600 ml/min) and the pulmonary vein pressure (PVP) was held constant at 5 cm H2O. PAP changes, therefore, were a direct index of PVR changes. Group 1 lobes underwent a full inflation from complete collapse to total lobe capacity (TLC) followed by a full deflation. Group 2 lobes underwent two deflation/inflation cycles, after an initial full inflation. These cycles, both beginning at TLC, had deflation end above and below CV, respectively. Significant PVR hysteresis was noted when the first inflation and deflation were compared. The maximum difference in PAP on deflation was 3.3 cm H2O or 11%. The mean decrease was 2.7 cm H2O for 18 lobes (p < 0.0001). The PAPs on all subsequent inflations or deflations that began above CV remained 9% lower than the initial inflation (n = 9, p < 0.0001), but were not different from each other. However, the final inflation which began from below CV resulted in a 30% return of PVR hysteresis (mean increase in PAP of 0.8 cm H2O, n = 7, p < 0.004). We conclude that there is hysteresis in the PVR response during ventilation, with decreased PVR during deflation relative to the initial inflation, that this hysteresis is absent when lung volume is maintained greater than CV, and that hysteresis returns when inflation occurs after deflation below CV. PMID:9769269

  2. Remedying magnetic hysteresis and 1/f noise for magnetoresistive sensors

    NASA Astrophysics Data System (ADS)

    Hu, Jiafei; Tian, Wugang; Zhao, Jianqiang; Pan, Mengchun; Chen, Dixiang; Tian, Guiyun

    2013-02-01

    Thermal domain hoppings cause magnetic hysteresis and 1/f resistance noise in magnetoresistive sensors, which largely degrades their response linearity and low-frequency detection ability. In this Letter, the method of constant magnetic excitation integrated with vertical motion flux modulation was proposed to remedy magnetic hysteresis and 1/f resistance noise together. As demonstrated in experiments, the response linearity of the prototype sensor is promoted by about 10 times. Its noise level is reduced to near Johnson-Nyquist noise level, and, therefore, the low-frequency detection ability is approximately enhanced with a factor of 100.

  3. Dynamical hysteresis in a self-oscillating polymer gel

    NASA Astrophysics Data System (ADS)

    Das, Debojyoti; Das, Moupriya; Ray, Deb Shankar

    2012-08-01

    An ionic polymer gel may undergo rhythmical swelling-deswelling kinetics induced by chemical oscillation. We demonstrate that the gel admits of dynamical hysteresis, which is manifested in the non-vanishing area of the response function—concentration (of reaction substrate) hysteresis loop, the response function being the integrated probability of residence of the polymer in any one of the swelled or deswelled states. The loop area depends on temperature and exhibits a turnover as a function of the strength of thermal noise—a phenomenon reminiscent of stochastic resonance. The numerical simulations agree well with our proposed analytical scheme.

  4. A survey on hysteresis modeling, identification and control

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Large-scale separation and hysteresis in cascades

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  6. Modeling of Switching and Hysteresis in Molecular Transport

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    USGS Publications Warehouse

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

    2007-01-01

    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.

  8. Wetting hysteresis and droplet roll off behavior on superhydrophobic surfaces by Katherine Marie Smyth.

    E-print Network

    Smyth, Katherine Marie

    2010-01-01

    Various states of hydrophobic wetting and hysteresis are observed when water droplets are deposited on micro-post surfaces of different post densities. Hysteresis is commonly defined as the difference between the advancing ...

  9. A Differential Model of Adsorption Hysteresis with Applications to Chromatography

    E-print Network

    Peszynska, Malgorzata

    A Differential Model of Adsorption Hysteresis with Applications to Chromatography M. Peszy- ena occuring in chromatography or other related disciplines, see [21]. These models have the general rise in the beginning of 20th century, chromatography has become a wide industrial domain delivering

  10. Inverse Compensation for Ferromagnetic Hysteresis Ralph C. Smith Rick Zrostlik

    E-print Network

    in Scientific Computation Etrema Products, Inc. North Carolina State University 2500 North Loop Drive Raleigh addresses the validation of an energy­ based inverse compensator for hysteresis in ferromag­ netic applications. In this paper, an ODE model based on magnetostatic energy principles is employed to characterize

  11. Perovskite–fullerene hybrid materials suppress hysteresis in planar diodes

    PubMed Central

    Xu, Jixian; Buin, Andrei; Ip, Alexander H.; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J.; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G.; Maksymovych, Peter; Sargent, Edward H.

    2015-01-01

    Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite–PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3? antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour. PMID:25953105

  12. A Free Energy Model for Hysteresis in Ferroelectric Materials

    E-print Network

    . This generates strains in the material and provides it with actuator capabilities. Alternatively, applied. The coupled converse and direct electromechanical effects are highly sensitive and repeatable which makes PZT, and extreme electromechanical sensitivity, also produce varying degrees of hysteresis and constitutive

  13. A Free Energy Model for Hysteresis in Ferroelectric Materials

    E-print Network

    . This generates strains in the material and provides it with actuator capabilities. Alternatively, applied#ects. The coupled converse and direct electromechanical e#ects are highly sensitive and repeatable which makes PZT#ects, and extreme electromechanical sensitivity, also produce varying degrees of hysteresis and constitutive

  14. Model and simulations of hysteresis in magnetic cores

    SciTech Connect

    Boley, C.D. ); Hodgdon, M.L. )

    1989-01-01

    Using a theory of ferromagnetic hysteresis developed recently, we present simulations of the behavior of a ferrite core connected in series with an initially charged capacitor. Results are given for three materials and are shown to compare favorably with experiment. 5 refs., 10 figs., 3 tabs.

  15. Intrinsic Hysteresis Loops Calculation of BZT Thin Films

    NASA Astrophysics Data System (ADS)

    Hikam, M.; Adnan, S. R.

    2014-04-01

    The Landau Devonshire (LK) simulation is utilized to calculate the intrinsic hysteresis properties of Barium Zirconium Titanate (BZT) doped by Indium and Lanthanum. A Delphi program run on Windows platform is used to facilitate the calculation. The simulation is very useful to calculate and understand the Gibbs free energy and the relationship between spontaneous polarization and electric field.

  16. Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes.

    PubMed

    Xu, Jixian; Buin, Andrei; Ip, Alexander H; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G; Maksymovych, Peter; Sargent, Edward H

    2015-01-01

    Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3(-) antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour. PMID:25953105

  17. Effect of hysteresis on moisture transport in porous building materials

    NASA Astrophysics Data System (ADS)

    Mad?ra, Ji?í; ?urana, Kamil; Ko?í, Jan; ?erný, Robert

    2012-09-01

    The influence of hysteresis of moisture transport properties on the hygrothermal performance of building envelopes is studied. Computational results reveal significant differences in moisture and relative humidity profiles calculated using the model with hysteretic parameters and without them. In addition, the introduction of hysteretic parameters results in worse hygrothermal performance from the water content point of view.

  18. Dynamic contact angles and hysteresis under electrowetting-on-dielectric.

    PubMed

    Nelson, Wyatt C; Sen, Prosenjit; Kim, Chang-Jin C J

    2011-08-16

    By designing and implementing a new experimental method, we have measured the dynamic advancing and receding contact angles and the resulting hysteresis of droplets under electrowetting-on-dielectric (EWOD). Measurements were obtained over wide ranges of applied EWOD voltages, or electrowetting numbers (0 ? Ew ? 0.9), and droplet sliding speeds, or capillary numbers (1.4 × 10(-5) ? Ca ? 6.9 × 10(-3)). If Ew or Ca is low, dynamic contact angle hysteresis is not affected much by the EWOD voltage or the sliding speed; that is, the hysteresis increases by less than 50% with a 2 order-of-magnitude increase in sliding speed when Ca < 10(-3). If both Ew and Ca are high, however, the hysteresis increases with either the EWOD voltage or the sliding speed. Stick-slip oscillations were observed at Ew > 0.4. Data are interpreted with simplified hydrodynamic (Cox-Voinov) and molecular-kinetic theory (MKT) models; the Cox-Voinov model captures the trend of the data, but it yields unreasonable fitting parameters. MKT fitting parameters associated with the advancing contact line are reasonable, but a lack of symmetry indicates that a more intricate model is required. PMID:21751778

  19. Hysteresis Can Grant Fitness in Stochastically Varying Environment

    PubMed Central

    Friedman, Gary; McCarthy, Stephen; Rachinskii, Dmitrii

    2014-01-01

    Although the existence of multiple stable phenotypes of living organisms enables random switching between phenotypes as well as non-random history dependent switching called hysteresis, only random switching has been considered in prior experimental and theoretical models of adaptation to variable environments. This work considers the possibility that hysteresis may also evolve together with random phenotype switching to maximize population growth. In addition to allowing the possibility that switching rates between different phenotypes may depend not only on a continuous environmental input variable, but also on the phenotype itself, the present work considers an opportunity cost of the switching events. This opportunity cost arises as a result of a lag phase experimentally observed after phenotype switching and stochastic behavior of the environmental input. It is shown that stochastic environmental variation results in maximal asymptotic growth rate when organisms display hysteresis for sufficiently slowly varying environmental input. At the same time, sinusoidal input does not cause evolution of memory suggesting that the connection between the lag phase, stochastic environmental variation and evolution of hysteresis is a result of a stochastic resonance type phenomenon. PMID:25068284

  20. Sensor Saturation for Hysteresis Reduction in GMR Magnetometers

    E-print Network

    Krchnavek, Robert R.

    Sensor Saturation for Hysteresis Reduction in GMR Magnetometers Philip S. Mease and Robert R technologies for the development of general-purpose magnetometers. They are applicable for both AC and DC of a magnetic field and instruments that make this measurement are known as magnetometers. The most common

  1. Causes and implications of colloid and microorganism retention hysteresis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  2. An Adaptive Control Method for Magnetostrictive Transducers with Hysteresis

    E-print Network

    and force require- ments, the transducer must operate in a regime in which the relation between inputAn Adaptive Control Method for Magnetostrictive Transducers with Hysteresis James M. Nealis of an adaptive control strategy for regulating the output of a proto- typical magnetostrictive transducer

  3. A Free Energy Model for Hysteresis in Magnetostrictive Transducers

    E-print Network

    A Free Energy Model for Hysteresis in Magnetostrictive Transducers Ralph C. Smith Marcelo J. Dapino This paper addresses the development of a free energy model for magnetostrictive transducers operating Introduction Magnetostrictive transducers are being considered for a number of high performance industrial, au

  4. A Free Energy Model for Hysteresis in Magnetostrictive Transducers

    E-print Network

    A Free Energy Model for Hysteresis in Magnetostrictive Transducers Ralph C. Smith Marcelo J. Dapino This paper addresses the development of a free energy model for magnetostrictive transducers operating;1 Introduction Magnetostrictive transducers are being considered for a number of high performance industrial, au

  5. A Domain Wall Model for Hysteresis in Piezoelectric Materials

    E-print Network

    nature of the materials and, more specifically, to domain switching in response to applied fields piezoelectric effects. As a result of the ferroelectric nature of the materials, they also exhibit varyingA Domain Wall Model for Hysteresis in Piezoelectric Materials Ralph C. Smith Center for Research

  6. Elastic guides reduce hysteresis effect in Belleville spring package

    NASA Technical Reports Server (NTRS)

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

    1967-01-01

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

  7. Periodic solutions of a forced system with hysteresis.

    NASA Technical Reports Server (NTRS)

    Drew, J. H.

    1972-01-01

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

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

    PubMed

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

    2013-08-01

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

  9. Modeling and Scaling of Hysteresis in Magnetic Materials. Frequency, Pick of Induction and Temperature Dependence

    E-print Network

    Krzysztof Z. Sokalski

    2015-10-15

    Recently introduced model of magnetic hysteresis was extended into set of the following features: frequency, pick of induction and temperature of specimen. Group theoretical classification of hysteresis loops' sets is presented. An effect analogous to the Zeeman splitting has been revealed in the set of the all hysteresis loops.

  10. Modeling and Scaling of Hysteresis in Magnetic Materials. Frequency, Pick of Induction and Temperature Dependence

    E-print Network

    Sokalski, Krzysztof Z

    2015-01-01

    Recently introduced model of magnetic hysteresis was extended into set of the following features: frequency, pick of induction and temperature of specimen. Group theoretical classification of hysteresis loops' sets is presented. An effect analogous to the Zeeman splitting has been revealed in the set of the all hysteresis loops.

  11. Hysteresis in the Dynamic Perception of Scenes and Objects Sonia Poltoratski and Frank Tong

    E-print Network

    Tong, Frank

    Hysteresis in the Dynamic Perception of Scenes and Objects Sonia Poltoratski and Frank Tong perception, or hysteresis, on the classification of the sequence: observers classified the sequence were perceived for longer on trials beginning with a scene view. This hysteresis effect resisted

  12. Extension of Hysteresis operators of Preisach-type to real, Lebesgue measurable

    E-print Network

    Iyer, Ram Venkataraman

    Extension of Hysteresis operators of Preisach-type to real, Lebesgue measurable functions R. Iyer. However, hysteresis operators of Preisach type have only been defined on much smaller space of regulated for continuous and regulated functions on an interval. Domain extension of hysteresis operators of Preisach type

  13. June 31, 1996 Measuring Hysteresis in Unemployment Rates with Long Memory Models

    E-print Network

    Crato, Nuno

    June 31, 1996 Measuring Hysteresis in Unemployment Rates with Long Memory Models Nuno Crato address the question of unemployment hysteresis within the context of ARFIMA models. Our results suggest that in the post-1973 era, hysteresis is considerably less of a stylized fact for the unemployment rates of key

  14. Bistability and hysteresis in the sliding friction of a dimer S. Gonalves,1,2,

    E-print Network

    Kenkre, V.M.

    Bistability and hysteresis in the sliding friction of a dimer S. Gonçalves,1,2, * C. Fusco,3,1, A and hysteresis, and can be related to earlier observations for extended systems such as the Frenkel-damped nonlinear oscillator. Increasing temperature tends to lower the resonant peak and wash out the hysteresis

  15. Effect of contact angle hysteresis on thermocapillary droplet actuation Jian Z. Chen

    E-print Network

    Troian, Sandra M.

    Effect of contact angle hysteresis on thermocapillary droplet actuation Jian Z. Chen Department-dimensional droplet driven by thermocapillary stresses including contact angle hysteresis. The results of this study highlight the critical role of chemical or mechanical hysteresis and the need to reduce this retentive force

  16. A Unified Model for Hysteresis in Ferroic Materials Ralph C. Smith

    E-print Network

    A Unified Model for Hysteresis in Ferroic Materials Ralph C. Smith , Stefan Seelecke , Marcelo J in hysteretic and nonlinear regimes. Whereas the physical mechanisms which produce hysteresis and constitutive. This unified methodology for quantifying hysteresis and constitutive nonlinearities for a broad class

  17. Systems with hysteresis in the feedback loop: existence, regularity and asymptotic behaviour of

    E-print Network

    Bath, University of

    Systems with hysteresis in the feedback loop: existence, regularity and asymptotic behaviour is proved for integral equations of convo- lution type which contain hysteresis nonlinearities. On the basis-dimensional system in the forward path and a hysteresis nonlinearity in the feedback path. These sta- bility criteria

  18. Hysteresis in Cenozoic Antarctic ice-sheet variations David Pollarda,*, Robert M. DeContob,1

    E-print Network

    Hysteresis in Cenozoic Antarctic ice-sheet variations David Pollarda,*, Robert M. DeContob,1, as found in earlier simple ice sheet models. Hysteresis effects are explored by running the model-linear Antarctic ice-sheet transitions and hysteresis have played important roles in many of the observed

  19. Introduction Hysteresis occurs in several phenomena. In physics we encounter it in plasticity, fric-

    E-print Network

    Visintin, Augusto

    Introduction Hysteresis occurs in several phenomena. In physics we encounter it in plasticity, fric. More generally, hysteresis arises in phase transitions, a typical example being undercooling effects materials. Hysteresis also occurs in engineering; thermostats are a very usual example. Others are met

  20. A Dynamic Hysteresis Model for THUNDER Transducers Brian L. Ball 1

    E-print Network

    A Dynamic Hysteresis Model for THUNDER Transducers Brian L. Ball 1 , Ralph C. Smith 2 and Zoubeida to the piezoceramic patch. A free energy based hysteretic stress-strain relation is employed to model hysteresis: THUNDER actuators, displacement model, hysteresis, piezoceramic, transition element, polariza- tion

  1. Construction and Experimental Implementation of a Model-Based Inverse Filter to Attenuate Hysteresis

    E-print Network

    Hysteresis in Ferroelectric Transducers Andrew G. Hatch and Ralph C. Smith Tathagata De and Murti V. Salapaka@iastate.edu, murti@iastate.edu rsmith@eos.ncsu.edu, aghatch@eos.ncsu.edu Abstract Hysteresis and constitutive hysteresis and constitutive nonlinearities at all drive levels. To illustrate, consider the prototypical

  2. Scale-Independent Hysteresis Switching ? ?? Jo~ao P. Hespanha 1 and A. Stephen Morse 2

    E-print Network

    Hespanha, João Pedro

    Scale-Independent Hysteresis Switching ? ?? Jo~ao P. Hespanha 1 and A. Stephen Morse 2 1 Dept logic inspired by the hysteresis switching logic considered in [7, 11]. The new logic also uses hysteresis to prevent chatter, but unlike its predecessor in [7, 11], it is \\scale-independent" as well

  3. Chaotic hysteresis in an adiabatically oscillating double well N. Berglund, H. Kunz

    E-print Network

    Berglund, Nils

    Chaotic hysteresis in an adiabatically oscillating double well N. Berglund, H. Kunz Institut de well. The system displays hysteresis effects which can be of periodic or chaotic type. We explain this behaviour by computing an analytic expression of a Poincar'e map. Although hysteresis is a quite familiar

  4. Highly Stable Hysteresis-Free Carbon Nanotube Thin-Film Transistors by Fluorocarbon Polymer Encapsulation

    E-print Network

    Javey, Ali

    Highly Stable Hysteresis-Free Carbon Nanotube Thin-Film Transistors by Fluorocarbon Polymer report hysteresis-free carbon nanotube thin-film transistors (CNT-TFTs) employing a fluorocarbon polymer them highly susceptible to the environment.37,38 Specifically, large hysteresis has been commonly

  5. A Hysteresis Model for Piezoceramic Materials Ralph C. Smith Zoubeida Ounaies

    E-print Network

    A Hysteresis Model for Piezoceramic Materials Ralph C. Smith Zoubeida Ounaies Center for Research of nonlinear constitutive relations and hysteresis inherent to piezo­ ceramic materials at moderate to high that they exhibit nearly linear dynamics and minimal hysteresis at low drive levels. The restriction

  6. Hysteresis Caused by Water Molecules in Carbon Nanotube Field-Effect

    E-print Network

    Javey, Ali

    Hysteresis Caused by Water Molecules in Carbon Nanotube Field-Effect Transistors Woong Kim, Ali that the transistors exhibit hysteresis in their electrical characteristics because of charge trapping by water molecules around the nanotubes, including SiO2 surface-bound water proximal to the nanotubes. Hysteresis

  7. Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented

    E-print Network

    Rubloff, Gary W.

    Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis of quaternary Ti­Ni­Cu­Pd SMAs and the thermal hysteresis are tailored. Novel alloys with near-zero thermal hysteresis, as predicted by the geometric non- linear theory of martensite, are identified. The thin

  8. An LDA-based relative hysteresis classifier with application to segmentation of retinal vessels

    E-print Network

    Lübeck, Universität zu

    An LDA-based relative hysteresis classifier with application to segmentation of retinal vessels. The proposed hysteresis classification makes use of such knowledge in an effi- cient way. We describe a novel, supervised, hysteresis- based classification method that we apply to the seg- mentation of retina

  9. A level-set approach for simulations of flows with multiple moving contact lines with hysteresis

    E-print Network

    Frey, Pascal

    A level-set approach for simulations of flows with multiple moving contact lines with hysteresis, a relation between contact-line speed and contact angle, slip and contact-line hysteresis. The convergence; Hysteresis 1. Introduction Incompressible two-phase flows with moving contact lines are common in a variety

  10. A hysteresis-free polymer-stabilised blue-phase liquid crystal , Daming Xua

    E-print Network

    Wu, Shin-Tson

    A hysteresis-free polymer-stabilised blue-phase liquid crystal Yifan Liua , Su Xua , Daming Xua hysteresis and good stability. Long ultraviolet (UV) wavelength and top-side (no IPS electrode) exposure create uniform polymer network, which in turn helps to suppress hysteresis. The effect of photoinitiator

  11. Interaction and Deformation of Elastic Bodies: Origin of Adhesion Hysteresis Phil Attard

    E-print Network

    Attard, Phil

    Interaction and Deformation of Elastic Bodies: Origin of Adhesion Hysteresis Phil Attard Ian Wark with a Lennard-Jones potential is obtained by solving self-consistently the elasticity equations. Hysteresis have been observed experimentally, is traced to limited equilibration and dynamic hysteresis

  12. Density hysteresis of heavy water confined in a nanoporous silica matrix

    E-print Network

    Chen, Sow-Hsin

    Density hysteresis of heavy water confined in a nanoporous silica matrix Yang Zhanga,b , Antonio and from 1 to 2,900 bars, where bulk water will crystalize. We observed a promi- nent hysteresis phenomenon this hysteresis phenomenon as support (although not a proof) of the hypothetical existence of a first-order liquid

  13. Numerical simulation for a two-phase porous medium flow problem with rate independent hysteresis$

    E-print Network

    Turova, Varvara

    Numerical simulation for a two-phase porous medium flow problem with rate independent hysteresis$ M¨unchen, Boltzmannstr. 3, 80807, Germany a r t i c l e i n f o Keywords: Two-phase flow Porous media Hysteresis Play and the saturations is described by a play-type hysteresis operator. We propose a numerical algorithm for treating

  14. Hysteresis and Noise from Electronic Nematicity in High-Temperature Superconductors E. W. Carlson,1

    E-print Network

    Carlson, Erica

    Hysteresis and Noise from Electronic Nematicity in High-Temperature Superconductors E. W. Carlson,1 (nematicity) using noise and hysteresis. In particular, we have uncovered a remarkably robust linear relation reported in recent noise [8] and hysteresis [9,10] measure- ments on high-temperature superconductors

  15. Hysteresis and Bistability in a Realistic Cell Model for Calcium Oscillations and Action Potential Firing

    E-print Network

    Gielen, C.C.A.M.

    Hysteresis and Bistability in a Realistic Cell Model for Calcium Oscillations and Action Potential parameter the model reveals a complex, rich spectrum of both stable and unstable solutions with hysteresis with hysteresis has also awakened a large interest in biology [7]. Instabilities, for instance, have been shown

  16. On periodicity of solutions for thermocontrol problems with hysteresis-type switches

    E-print Network

    Fiedler, Bernold

    On periodicity of solutions for thermocontrol problems with hysteresis-type switches P. Gurevich, W the same value as "just before." Thus, the presence of the operator H provides the so-called hysteresis of solutions for two-phase Stefan problems with the Robin boundary condition involving a hysteresis control

  17. Capacitance hysteresis in GaN/AlGaN heterostructures L. E. Byrum,1

    E-print Network

    Dietz, Nikolaus

    Capacitance hysteresis in GaN/AlGaN heterostructures L. E. Byrum,1 G. Ariyawansa,1 R. C. Jayasinghe hysteresis have been attributed to trap energy states located just above the Fermi level at the GaN/AlGaN interface, most likely due to N-vacancy and/or C-donor impurities. The presence of the hysteresis is due

  18. Supervised, hysteresis-based segmentation of retinal images using the linear-classifier percentile

    E-print Network

    Lübeck, Universität zu

    Supervised, hysteresis-based segmentation of retinal images using the linear-classifier percentile, supervised, hysteresis-based classification algorithm that we apply to the segmentation of retina segmentation is similar to a bi- nary (i.e., two-class) pattern classification problem. The hysteresis

  19. Hysteresis during Cycling of Nickel Hydroxide Active Material Venkat Srinivasan,a,

    E-print Network

    Weidner, John W.

    Hysteresis during Cycling of Nickel Hydroxide Active Material Venkat Srinivasan,a, *,c John W, Berkeley, California 94720, USA The nickel hydroxide electrode is known to exhibit a stable hysteresis loop electronically July 31, 2001. Hysteresis is a characteristic of a system in which a change in the direction

  20. A Model for RateDependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies

    E-print Network

    A Model for Rate­Dependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies Ralph contribute to hysteresis inherent to piezoelectric materials operating at low frequencies. While quasistatic the full capabilities of the materials. The model employed here quantifies the hysteresis in two steps

  1. Hysteresis Modeling and Compensation for an XY Micropositioning Stage with Model Reference Adaptive Control

    E-print Network

    Li, Yangmin

    Hysteresis Modeling and Compensation for an XY Micropositioning Stage with Model Reference Adaptive to compensate for the hysteresis effects aiming at a sub-micron accuracy motion tracking control. To convert the desired motion trajectory into voltage input, the inverse modified Prandtl-Ishlinskii (PI) hysteresis

  2. Adaptive Neural Control for Uncertain Nonlinear Systems in Pure-feedback Form with Hysteresis Input

    E-print Network

    Ge, Shuzhi Sam

    Adaptive Neural Control for Uncertain Nonlinear Systems in Pure-feedback Form with Hysteresis Input with the generalized Prandtl-Ishlinskii hysteresis input. The non-affine problem both in the pure-feedback form and in the generalized Prandtl-Ishlinskii hysteresis input func- tion is solved by adopting the Mean Value Theorem

  3. HYSTERESIS IN A ROTATING DIFFERENTIALLY HEATED SPHERICAL SHELL OF BOUSSINESQ FLUID

    E-print Network

    Lewis, Greg

    HYSTERESIS IN A ROTATING DIFFERENTIALLY HEATED SPHERICAL SHELL OF BOUSSINESQ FLUID GREGORY M in a codimension-2 hysteresis bifurcation (or cusp) point, providing a mechanism for hysteretic transitions between different cell patterns as the temperature gradient is varied. Key words. cusp point, hysteresis bifurcation

  4. Archimedes Curves

    ERIC Educational Resources Information Center

    Swain, Gordon A.

    2013-01-01

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

  5. Phase Transitions, Hysteresis, and Hyperbolicity for Self-Organized Alignment Dynamics

    NASA Astrophysics Data System (ADS)

    Degond, Pierre; Frouvelle, Amic; Liu, Jian-Guo

    2015-04-01

    We provide a complete and rigorous description of phase transitions for kinetic models of self-propelled particles interacting through alignment. These models exhibit a competition between alignment and noise. Both the alignment frequency and noise intensity depend on a measure of the local alignment. We show that, in the spatially homogeneous case, the phase transition features (number and nature of equilibria, stability, convergence rate, phase diagram, hysteresis) are totally encoded in how the ratio between the alignment and noise intensities depend on the local alignment. In the spatially inhomogeneous case, we derive the macroscopic models associated to the stable equilibria and classify their hyperbolicity according to the same function.

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

    NASA Astrophysics Data System (ADS)

    Zheng, Jiashan; Wang, Yifu

    2015-06-01

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

  7. Unconventional Magnetic and Resistive Hysteresis in an Iodine-Bonded Molecular Conductor.

    PubMed

    Kawaguchi, Genta; Maesato, Mitsuhiko; Komatsu, Tokutaro; Kitagawa, Hiroshi; Imakubo, Tatsuro; Kiswandhi, Andhika; Graf, David; Brooks, James S

    2015-08-24

    Simultaneous manipulation of both spin and charge is a crucial issue in magnetic conductors. We report on a strong correlation between magnetism and conductivity in the iodine-bonded molecular conductor (DIETSe)2 FeBr2 Cl2 [DIETSe=diiodo(ethylenedithio)tetraselenafulvalene], which is the first molecular conductor showing a large hysteresis in both magnetic moment and magnetoresistance associated with a spin-flop transition. Utilizing a mixed-anion approach and iodine bonding interactions, we tailored a molecular conductor with random exchange interactions exhibiting unforeseen physical properties. PMID:26179678

  8. Diffraction hysteresis loop modelisation in transverse magneto-optical Kerr effect

    NASA Astrophysics Data System (ADS)

    Vial, Alexandre; Van Labeke, Daniel

    1998-07-01

    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.

  9. Hysteresis in the dynamic perception of scenes and objects.

    PubMed

    Poltoratski, Sonia; Tong, Frank

    2014-10-01

    Scenes and objects are effortlessly processed and integrated by the human visual system. Given the distinct neural and behavioral substrates of scene and object processing, it is likely that individuals sometimes preferentially rely on one process or the other when viewing canonical "scene" or "object" stimuli. This would allow the visual system to maximize the specific benefits of these 2 types of processing. It is less obvious which of these modes of perception would be invoked during naturalistic visual transition between a focused view of a single object and an expansive view of an entire scene, particularly at intermediate views that may not be assigned readily to either stimulus category. In the current study, we asked observers to report their online perception of such dynamic image sequences, which zoomed and panned between a canonical view of a single object and an entire scene. We found a large and consistent effect of prior perception, or hysteresis, on the classification of the sequence: observers classified the sequence as an object for several seconds longer if the trial started at the object view and zoomed out, whereas scenes were perceived for longer on trials beginning with a scene view. This hysteresis effect resisted several manipulations of the movie stimulus and of the task performed, but hinged on the perceptual history built by unidirectional progression through the image sequence. Multiple experiments confirmed that this hysteresis effect was not purely decisional and was more prominent for transitions between corresponding objects and scenes than between other high-level stimulus classes. This finding suggests that the competitive mechanisms underlying hysteresis may be especially prominent in the perception of objects and scenes. We propose that hysteresis aids in disambiguating perception during naturalistic visual transitions, which may facilitate a dynamic balance between scene and object processing to enhance processing efficiency. PMID:25150947

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

    USGS Publications Warehouse

    Landers, Mark N.; Sturm, Terry W.

    2013-01-01

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

  11. Magnetic anisotropy, unusual hysteresis and putative "up-up-down" magnetic structure in EuTAl4Si2 (T = Rh and Ir).

    PubMed

    Maurya, Arvind; Thamizhavel, A; Dhar, S K; Bonville, P

    2015-01-01

    We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu(2+)being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an "up-up-down" magnetic structure in zero field. PMID:26156410

  12. Magnetic anisotropy, unusual hysteresis and putative “up-up-down” magnetic structure in EuTAl4Si2 (T = Rh and Ir)

    PubMed Central

    Maurya, Arvind; Thamizhavel, A.; Dhar, S. K.; Bonville, P.

    2015-01-01

    We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu2+being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an “up-up-down” magnetic structure in zero field. PMID:26156410

  13. Magnetic anisotropy, unusual hysteresis and putative “up-up-down” magnetic structure in EuTAl4Si2 (T = Rh and Ir)

    NASA Astrophysics Data System (ADS)

    Maurya, Arvind; Thamizhavel, A.; Dhar, S. K.; Bonville, P.

    2015-07-01

    We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1?=?11.7 and 14.7?K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu2+being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8?K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3?M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an “up-up-down” magnetic structure in zero field.

  14. Isolated Curves for Hyperelliptic Curve Cryptography

    E-print Network

    Wang, Wenhan

    2012-01-01

    We introduce the notion of isolated genus two curves. As there is no known efficient algorithm to explicitly construct isogenies between two genus two curves with large conductor gap, the discrete log problem (DLP) cannot be efficiently carried over from an isolated curve to a large set of isogenous curves. Thus isolated genus two curves might be more secure for DLP based hyperelliptic curve cryptography. We establish results on explicit expressions for the index of an endomorphism ring in the maximal CM order, and give conditions under which the index is a prime number or an almost prime number for three different categories of quartic CM fields. We also derived heuristic asymptotic results on the densities and distributions of isolated genus two curves with CM by any fixed quartic CM field. Computational results, which are also shown for three explicit examples, agree with heuristic prediction with errors within a tolerable range.

  15. Darwin curves and galaxy arms

    NASA Astrophysics Data System (ADS)

    He, Jin

    2014-07-01

    In the natural world, there exists one kind of structure which is beyond the scope of human laboratorial experiment. It is the structure of galaxies which is usually composed of billions of stars. Spiral galaxies are flat disk-shaped. There are two types of spiral galaxies. The spiral galaxies with some bar-shaped pattern are called barred spirals, and the ones without the pattern are called ordinary spirals. Longer-wavelength galaxy images (infrared, for example) show that ordinary spiral galaxies are basically an axi-symmetric disk that is called exponential disk. For a planar distribution of matter, Jin He defined Darwin curves in the plane as such that the ratio of the matter densities at both sides of the curve is constant along the curve. Therefore, the arms of ordinary spiral galaxies are Darwin curves. Now an important question is that: Are the arms of barred spiral galaxies the Darwin curves too? Fortunately, Jin He designed a piece of Galaxy Anatomy graphic software. With the software, not only can people simulate the stellar density distribution of barred spiral galaxies but also can draw the Darwin curves of the simulated galaxy structure. This paper shows partial evidence that the arms of galaxy NGC 3275, 4548 and 5921 follow Darwin curves.

  16. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    PubMed Central

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-01-01

    Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. PMID:26482650

  17. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-10-01

    Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.

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

    SciTech Connect

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

    1992-01-01

    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.

  19. String networks as tropical curves

    NASA Astrophysics Data System (ADS)

    Ray, Koushik

    2008-09-01

    A prescription for obtaining supergravity solutions for planar (p,q)-string networks is presented, based on earlier results. It shows that networks may be looked upon as tropical curves emerging as the spine of the amoeba of a holomorphic curve in M-theory. The Kähler potential of supergravity is identified with the corresponding Ronkin function. Implications of this identification in counting dyons is discussed.

  20. Complete denture retention. Part I: Physical analysis of the mechanism. Hysteresis of the solid-liquid contact angle.

    PubMed

    Monsénégo, P; Proust, J

    1989-08-01

    Analysis of physical forces involved in the mechanism of denture retention clearly shows that the hysteresis of the liquid-solid contact angle governs the viscoelastic response of the system dislodgment. This result is in contradiction to the most commonly admitted view according to which perfect wettability is necessary to obtain good retention and implies the existence of the high advancing contact angle of saliva on a prosthetic material. PMID:2668514

  1. Charge state hysteresis in semiconductor quantum dots

    SciTech Connect

    Yang, C. H.; Rossi, A. Lai, N. S.; Leon, R.; Lim, W. H.; Dzurak, A. S.

    2014-11-03

    Semiconductor quantum dots provide a two-dimensional analogy for real atoms and show promise for the implementation of scalable quantum computers. Here, we investigate the charge configurations in a silicon metal-oxide-semiconductor double quantum dot tunnel coupled to a single reservoir of electrons. By operating the system in the few-electron regime, the stability diagram shows hysteretic tunnelling events that depend on the history of the dots charge occupancy. We present a model which accounts for the observed hysteretic behaviour by extending the established description for transport in double dots coupled to two reservoirs. We demonstrate that this type of device operates like a single-electron memory latch.

  2. Adaptive Dynamic Surface Control for a Class of Strict-Feedback Nonlinear Systems with Unknown Backlash-Like Hysteresis

    E-print Network

    Ge, Shuzhi Sam

    Backlash-Like Hysteresis Beibei Ren, Phyo Phyo San, Shuzhi Sam Ge and Tong Heng Lee Abstract by unknown backlash-like hysteresis. Using the characteristics of backlash-like hysteresis, adaptive dynamic surface control (DSC) is developed without constructing a hysteresis inverse. The explosion of complexity

  3. Low-gain integral control of in nite-dimensional regular linear systems subject to input hysteresis

    E-print Network

    Bath, University of

    hysteresis #3; H. LOGEMANN and A.D. MAWBY Department of Mathematical Sciences, University of Bath, Bath BA2 7 hysteresis, backlash and hysteresis operators of Prandtl and Preisach type. Keywords: Regular in#12;nite-dimensional systems; integral control; hysteresis nonlineari- ties; robust tracking. AMS subject classi#12;cations: 93

  4. A Particle-Water Based Model for Water Retention Hysteresis

    E-print Network

    Yixiang Gan; Federico Maggi; Giuseppe Buscarnera; Itai Einav

    2013-12-04

    A particle-water discrete element based approach to describe water movement in partially saturated granular media is presented and tested. Water potential is governed by both capillary bridges, dominant at low saturations, and the pressure of entrapped air, dominant at high saturations. The approach captures the hysteresis of water retention during wetting and drainage by introducing the local evolution of liquid-solid contact angles at the level of pores and grains. Extensive comparisons against experimental data are presented. While these are made without the involvement of any fitting parameters, the method demonstrates relative high success by achieving a correlation coefficient of at least 82%, and mostly above 90%. For the tested materials with relatively mono-disperse grain size, the hysteresis of water retention during cycles of wetting and drainage has been shown to arise from the dynamics of solid-liquid contact angles as a function of local liquid volume changes.

  5. Hysteresis and Kinetic Effects During Liquid-Solid Transitions

    SciTech Connect

    Streitz, F H; Chau, R

    2009-02-17

    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.

  6. Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization

    PubMed Central

    Farrahi, Assal; Sanz-Andrés, Ángel

    2013-01-01

    A semiempirical method for predicting the damping efficiency of hysteresis rods on-board small satellites is presented. It is based on the evaluation of dissipating energy variation of different ferromagnetic materials for two different rod shapes: thin film and circular cross-section rods, as a function of their elongation. Based on this formulation, an optimum design considering the size of hysteresis rods, their cross section shape, and layout has been proposed. Finally, the formulation developed was applied to the case of four existing small satellites, whose corresponding in-flight data are published. A good agreement between the estimated rotational speed decay time and the in-flight data has been observed. PMID:24501579

  7. Hysteresis in the Underdamped Driven Frenkel-Kontorova Model

    SciTech Connect

    Braun, O.M.; Bishop, A.R.; Roeder, J.; Braun, O.M.

    1997-11-01

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

  8. Hysteresis in swelling and in sorption of wood tissue.

    PubMed

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

    2013-06-01

    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

  9. Method of thermal strain hysteresis reduction in metal matrix composites

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Fraedrich, K.

    2012-05-01

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

  11. Hysteresis and remanence in magnetoelectric effects in functionally graded magnetostrictive-piezoelectric layered composites

    NASA Astrophysics Data System (ADS)

    Laletin, U.; Sreenivasulu, G.; Petrov, V. M.; Garg, T.; Kulkarni, A. R.; Venkataramani, N.; Srinivasan, G.

    2012-03-01

    The observation and theory of a large remanent magnetoelectric (ME) coefficient and coercivity in the static field H dependence of the low-frequency ME effects are reported for bilayers of lead zirconate titanate (PZT) and a functionally graded ferromagnetic layer. The grading involves magnetization with the use of nickel zinc ferrite of composition Ni0.7Zn0.3Fe2O4 (NZFO) and pure Ni. In homogeneous bilayers of PZT-Ni or PZT-NZFO, the ME voltage coefficient (MEVC) vs H data do not show any hysteresis or remanence. Upon grading the ferromagnetic layer, significant changes including hysteresis and remanece are observed. In PZT-Ni-NZFO, MEVC vs H data show a positive remnant MEVC and a negative coercive field. When the grading is reversed, in samples of PZT-NZFO-Ni, the remnant MEVC is negative and the coercive field is positive. A theory is proposed for the low-frequency ME effects in the graded composites. According to the model, the grading in the magnetization leads to a built-in magnetic field in the ferromagnetic layer, and this field depends on the sequence of grading and the thickness of the NZFO and Ni layers. As a result, the total torque moment and flexural deformations in the composite and the bias field dependence of ME voltage coefficient becomes strongly hysteretic. Calculated MEVC vs H, remnant MEVC, and coercive field are in good agreement with the data.

  12. Domain-wall motion in random potential and hysteresis modeling

    SciTech Connect

    Pasquale, M.; Basso, V.; Bertotti, G.; Jiles, D.C.; Bi, Y.

    1998-06-01

    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.}

  13. Barkhausen discontinuities and hysteresis of ferromagnetics: New stochastic approach

    SciTech Connect

    Vengrinovich, Valeriy

    2014-02-18

    The magnetization of ferromagnetic material is considered as periodically inhomogeneous Markov process. The theory assumes both statistically independent and correlated Barkhausen discontinuities. The model, based on the chain evolution-type process theory, assumes that the domain structure of a ferromagnet passes successively the steps of: linear growing, exponential acceleration and domains annihilation to zero density at magnetic saturation. The solution of stochastic differential Kolmogorov equation enables the hysteresis loop calculus.

  14. Hysteresis and nonequilibrium work theorem for DNA unzipping

    E-print Network

    Rajeev Kapri

    2012-10-09

    We study by using Monte Carlo simulations the hysteresis in unzipping and rezipping of a double stranded DNA (dsDNA) by pulling its strands in opposite directions in the fixed force ensemble. The force is increased, at a constant rate from an initial value $g_0$ to some maximum value $g_m$ that lies above the phase boundary and then decreased back again to $g_{0}$. We observed hysteresis during a complete cycle of unzipping and rezipping. We obtained probability distributions of work performed over a cycle of unzipping and rezipping for various pulling rates. The mean of the distribution is found to be close (the difference being within 10%, except for very fast pulling) to the area of the hysteresis loop. We extract the equilibrium force versus separation isotherm by using the work theorem on repeated non-equilibrium force measurements. Our method is capable of reproducing the equilibrium and the non-equilibrium force-separation isotherms for the spontaneous rezipping of dsDNA.

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

    SciTech Connect

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

    2012-03-01

    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.

  16. Light-induced hysteresis and recovery behaviors in photochemically activated solution-processed metal-oxide thin-film transistors

    SciTech Connect

    Jo, Jeong-Wan; Park, Sung Kyu E-mail: skpark@cau.ac.kr; Kim, Yong-Hoon E-mail: skpark@cau.ac.kr

    2014-07-28

    In this report, photo-induced hysteresis, threshold voltage (V{sub T}) shift, and recovery behaviors in photochemically activated solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) are investigated. It was observed that a white light illumination caused negative V{sub T} shift along with creation of clockwise hysteresis in electrical characteristics which can be attributed to photo-generated doubly ionized oxygen vacancies at the semiconductor/gate dielectric interface. More importantly, the photochemically activated IGZO TFTs showed much reduced overall V{sub T} shift compared to thermally annealed TFTs. Reduced number of donor-like interface states creation under light illumination and more facile neutralization of ionized oxygen vacancies by electron capture under positive gate potential are claimed to be the origin of the less V{sub T} shift in photochemically activated TFTs.

  17. Entropy Production and the Pressure-Volume Curve of the Lung

    E-print Network

    Oliveira, Cláudio L N; Bates, Jason H T; Andrade, José S; Suki, Béla

    2015-01-01

    We investigate analytically the production of entropy during a breathing cycle in healthy and diseased lungs. First, we calculate entropy production in healthy lungs by applying the laws of thermodynamics to the well-known transpulmonary pressure-volume ($P-V$) curves of the lung under the assumption that lung tissue behaves as an entropy spring-like rubber. The bulk modulus, $B$, of the lung is also derived from these calculations. Second, we extend this approach to elastic recoil disorders of the lung such as occur in pulmonary fibrosis and emphysema. These diseases are characterized by particular alterations in the $P-V$ relationship. For example, in fibrotic lungs $B$ increases monotonically with disease progression, while in emphysema the opposite occurs. These diseases can thus be mimicked simply by making appropriate adjustments to the parameters of the $P-V$ curve. Using Clausius's formalism, we show that entropy production, $\\Delta S$, is related to the hysteresis area, $\\Delta A$, enclosed by the $P...

  18. Multivariate Analysis of the Ocular Response Analyzer's Corneal Deformation Response Curve for Early Keratoconus Detection

    PubMed Central

    Galletti, Jonatán D.; Ruiseñor Vázquez, Pablo R.; Fuentes Bonthoux, Fernando; Pförtner, Tomás; Galletti, Jeremías G.

    2015-01-01

    Purpose. To thoroughly analyze corneal deformation responses curves obtained by Ocular Response Analyzer (ORA) testing in order to improve subclinical keratoconus detection. Methods. Observational case series of 87 control and 73 subclinical keratoconus eyes. Examination included corneal topography, tomography, and biomechanical testing with ORA. Factor analysis, logistic regression, and receiver operating characteristic curves were used to extract combinations of 45 corneal waveform descriptors. Main outcome measures were corneal-thickness-corrected corneal resistance factor (ccCRF), combinations of corneal descriptors, and their diagnostic performance. Results. Thirty-seven descriptors differed significantly in means between groups, and among them ccCRF afforded the highest individual diagnostic performance. Factor analysis identified first- and second-peak related descriptors as the most variable one. However, conventional biomechanical descriptors corneal resistance factor and hysteresis differed the most between control and keratoconic eyes. A combination of three factors including several corneal descriptors did not show better diagnostic performance than a combination of conventional indices. Conclusion. Multivariate analysis of ORA signals did not surpass simpler models in subclinical keratoconus detection, and there is considerable overlap between normal and ectatic eyes irrespective of the analysis model. Conventional biomechanical indices seem to already provide the best performance when appropriately considered. PMID:26075085

  19. CRSC-TR04-38 High-precision first-order reversal curve (FORC) functions for single-domain

    E-print Network

    , NC 27695-8208 Plots of the first-order reversal curve (FORC) function are used to characterize magnetists use magnetic hysteresis measurements to characterize ferro- magnetic minerals in rocks for estimating mineral size, but its inter- pretation is highly ambiguous. One reason for ambiguity

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  1. Double hysteresis loops and large negative and positive electrocaloric effects in tetragonal ferroelectrics.

    PubMed

    Wu, Hong-Hui; Zhu, Jiaming; Zhang, Tong-Yi

    2015-10-01

    Phase field modelling and thermodynamic analysis are employed to investigate depolarization and compression induced large negative and positive electrocaloric effects (ECEs) in ferroelectric tetragonal crystalline nanoparticles. The results show that double-hysteresis loops of polarization versus electric field dominate at temperatures below the Curie temperature of the ferroelectric material, when the mechanical compression exceeds a critical value. In addition to the mechanism of pseudo-first-order phase transition (PFOPT), the double-hysteresis loops are also caused by the abrupt rise of macroscopic polarization from the abc phase to the c phase or the sudden fall of macroscopic polarization from the c phase to the abc phase when the temperature increases. This phenomenon is called the electric-field-induced-pseudo-phase transition (EFIPPT) in the present study. Similar to the two types of PFOPTs, the two types of EFIPPTs cause large negative and positive ECEs, respectively, and give the maximum absolute values of negative and positive adiabatic temperature change (ATC ?T). The temperature associated with the maximum absolute value of negative ATC ?T is lower than that associated with the maximum positive ATC ?T. Both maximum absolute values of ATC ?Ts change with the variation in the magnitude of an applied electric field and depend greatly on the compression intensity. PMID:26307461

  2. On the explanation of hysteresis in the adsorption of ammonia on graphitized thermal carbon black.

    PubMed

    Zeng, Yonghong; Do, D D; Horikawa, Toshihide; Nicholson, D; Nakai, Kazuyuki

    2015-12-23

    We present a Monte Carlo simulation and experimental study of ammonia adsorption on graphitized thermal carbon black. Our new molecular model for the adsorbent is composed of basal plane graphene surfaces with ultrafine pores grafted with hydroxyl groups at the junctions between graphene layers. The simulated adsorption isotherms and isosteric heats are in good agreement with the experimental data of Holmes and Beebe, and the simulations reproduce the unusual experimental hysteresis of ammonia adsorption on an open graphite surface for the first time in the literature. The detailed mechanisms of adsorption and desorption, and the origin of hysteresis, are investigated by the microscopic analysis of the adsorbate structures to show that restructuring occurs during adsorption. The main results from this work are: (i) at the triple point, ammonia adsorbs preferentially around the functional groups to form clusters in the ultrafine pores and spills-over onto the basal plane as the loading is increased; followed by a 2D condensation on the graphite surface to form a bilayer adsorbate; (ii) at the boiling point, adsorption occurs on the basal plane due to the increasing importance of thermal fluctuations (an entropic effect); (iii) the isosteric heat is very high at zero loading due to the strong interaction between ammonia and the functional groups, decreases steeply when the functional group is saturated, and eventually reaches the heat of condensation as the fluid-fluid interaction increases. PMID:26661571

  3. Simple models for dynamic hysteresis loops calculation: Application to hyperthermia optimization

    E-print Network

    Carrey, J; Respaud, M

    2010-01-01

    To optimize the heating properties of magnetic nanoparticles (MNPs) in magnetic hyperthermia applications, it is necessary to calculate the area of their hysteresis loops in an alternating magnetic field. The three types of theories suitable to describe the hysteresis loops of MNPs are presented and compared to numerical simulations: equilibrium functions, Stoner-Wohlfarth model based theories (SWMBTs) and linear response theory (LRT). Suitable formulas to calculate the hysteresis area of major cycles are deduced from SWMBTs and from numerical simulations; the domain of validity of the analytical formula is explicitly studied. In the case of minor cycles, the hysteresis area calculations are based on the LRT. A perfect agreement between LRT and numerical simulations of hysteresis loops is obtained. The domain of validity of the LRT is explicitly studied. Formulas to calculate the hysteresis area at low field valid for any anisotropy of the MNP are proposed. Numerical simulations of the magnetic field dependen...

  4. Hysteresis behavior of Blume-Capel model on a cylindrical Ising nanotube

    NASA Astrophysics Data System (ADS)

    Canko, Osman; Ta?k?n, Ferhat; Argin, Kamil; Erdinç, Ahmet

    2014-04-01

    We have investigated Blume-Capel model on a cylindrical Ising nanotube by using the effective field theory with correlations. Hysteresis loops, magnetic susceptibility and coercivities have been calculated numerically for ferromagnetic and antiferromagnetic cases. When interactions are low between the core and shell sites, double and triple hysteresis loops can be seen in the system for ferro- and antiferromagnetic interactions, respectively. The effect of temperature has been examined on hysteresis loops and dependencies of coercivity based on temperature are depicted.

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

    NASA Technical Reports Server (NTRS)

    Covert, E. E.

    1979-01-01

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

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

    SciTech Connect

    Kim, Yunseok; Yang, J.-C.; Chu, Ying Hao; Yu, Pu; Lu, X.; Jesse, Stephen; Kalinin, Sergei V

    2012-01-01

    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.

  7. A storage-extended rating curve for sediment flux estimation

    NASA Astrophysics Data System (ADS)

    Fink, Gabriel; Wüest, Alfred

    2014-05-01

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

  8. Magnetoresistance and capacitance oscillations and hysteresis in type-II InAsSbP ellipsoidal quantum dots

    NASA Astrophysics Data System (ADS)

    Gambaryan, K. M.; Harutyunyan, V. G.; Aroutiounian, V. M.; Ai, Y.; Ashalley, E.; Wang, Z. M.

    2015-06-01

    The InAsSbP composition type-II quantum dots (QDs) are grown on a InAs(1?0?0) substrate from In-As-Sb-P quaternary liquid phase at a constant temperature in Stranski-Krastanow growth mode. Device structures in the form of photoconductive cells are prepared for investigation. Magnetospectroscopy and high-precision capacitance spectrometry are used to explore the QDs structure’s electric sheet resistance in a magnetic field and the capacitance (charge) law at lateral current flow. Aharonov-Bohm (AB) oscillations with the period of ?B = 0.38???±???0.04?T are found on the magnetoresistance curve at both room and liquid nitrogen temperatures. The influence of the QDs size distribution on the period of AB oscillations is investigated. The magnetoresistance hysteresis equals to ~50?m? and ~400?m? is revealed at room and liquid nitrogen temperature, respectively. The capacitance hysteresis (CH) and contra-directional oscillations are also detected. Behavior of the CH versus applied voltage frequency in the range f = 103-106?Hz is investigated. It is shown that the CH decreases with increasing frequency up to 106?Hz. The time constant and corresponding frequency for the QDs R-C parallel circuit (generator) equal to ? = 2.9???×???10-7?s and f?0 = 5.5???×???105?Hz, respectively, are calculated.

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

    SciTech Connect

    Sarshar, Mohammad Amin; Swarctz, Christopher; Hunter, Scott Robert; Simpson, John T; Choi, Chang-Hwan

    2012-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  11. Transient multi-physics analysis of a magnetorheological shock absorber with the inverse Jiles-Atherton hysteresis model

    NASA Astrophysics Data System (ADS)

    Zheng, Jiajia; Li, Yancheng; Li, Zhaochun; Wang, Jiong

    2015-10-01

    This paper presents multi-physics modeling of an MR absorber considering the magnetic hysteresis to capture the nonlinear relationship between the applied current and the generated force under impact loading. The magnetic field, temperature field, and fluid dynamics are represented by the Maxwell equations, conjugate heat transfer equations, and Navier-Stokes equations. These fields are coupled through the apparent viscosity and the magnetic force, both of which in turn depend on the magnetic flux density and the temperature. Based on a parametric study, an inverse Jiles-Atherton hysteresis model is used and implemented for the magnetic field simulation. The temperature rise of the MR fluid in the annular gap caused by core loss (i.e. eddy current loss and hysteresis loss) and fluid motion is computed to investigate the current-force behavior. A group of impulsive tests was performed for the manufactured MR absorber with step exciting currents. The numerical and experimental results showed good agreement, which validates the effectiveness of the proposed multi-physics FEA model.

  12. Hysteresis model of shape memory alloy wire-based laminated rubber bearing under compression and unidirectional shear loadings

    NASA Astrophysics Data System (ADS)

    Hedayati Dezfuli, F.; Shahria Alam, M.

    2015-06-01

    Smart lead rubber bearings (LRBs), in which a shape memory alloy (SMA) is used in the form of wires, are a new generation of elastomeric isolators with improved performance in terms of recentering capability and energy dissipation capacity. It is of great interest to implement SMA wire-based lead rubber bearings (SMA-LRBs) in bridges; however, currently there is no appropriate hysteresis model for accurately simulating the behavior of such isolators. A constitutive model for SMA-LRBs is proposed in this study. An LRB is equipped with a double cross configuration of SMA wires (DC-SMAW) and subjected to compression and unidirectional shear loadings. Due to the complexity of the shear behavior of the SMA-LRB, a hysteresis model is developed for the DC-SMAWs and then combined with the bilinear kinematic hardening model, which is assumed for the LRB. Comparing the hysteretic response of decoupled systems with that of the SMA-LRB shows that the high recentering capability of the DC-SMAW model with zero residual deformation could noticeably reduce the residual deformation of the LRB. The developed constitutive model for DC-SMAWs is characterized by three stiffnesses when the shear strain exceeds a starting limit at which the SMA wires are activated due to phase transformation. An important point is that the shear hysteresis of the DC-SMAW model looks different from the flag-shaped hysteresis of the SMA because of the specific arrangement of wires and its effect on the resultant forces transferred from the wires to the rubber bearing.

  13. Quadrupole hysteresis in uniaxial magnet with unity spin

    NASA Astrophysics Data System (ADS)

    Shapovalov, I. P.; Sayko, P. A.

    2013-12-01

    Uniaxial spin-1 magnets with tensor interactions have been studied in the absence of external magnetic field. The model with the most general form of interactions for the uniaxial symmetry has been investigated. Conditions for the implementation of only two quadrupole phases are considered: the phase with a quadrupole ordering along the lattice symmetry axis and the phase with ordering in the plane normal to the lattice symmetry axis. It has been shown that components of the quadrupole order parameter as a function of the single-ion anisotropy constant at low temperatures has "hysteresis" character. An analytical expression for the remagnetization energy per lattice site has been obtained.

  14. Hysteresis in a magnetic bead and its applications

    E-print Network

    Vanchna Singh; Varsha Banerjee

    2012-08-27

    We study hysteresis in a micron-sized bead: a non-magnetic matrix embedded with super- paramagnetic nanoparticles. These hold tremendous promise in therapeutic applications as heat generating machines. The theoretical formulation uses a mean-field theory to account for dipolar interactions between the supermoments. The study enables manipulation of heat dissipation by a compatible selection of commercially available beads and the frequency f and amplitude ho of the applied oscillating field in the labortory. We also introduce the possibility of utilizing return point memory for gradual heating of a local region.

  15. Effect of contact angle hysteresis on moving liquid film integrity.

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  16. Effect of contact angle hysteresis on moving liquid film integrity

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  18. Dynamic hysteresis behaviors for the two-dimensional mixed spin (2, 5/2) ferrimagnetic Ising model in an oscillating magnetic field

    NASA Astrophysics Data System (ADS)

    Erta?, Mehmet

    2015-09-01

    Keskin and Erta? (2009) presented a study of the magnetic properties of a mixed spin (2, 5/2) ferrimagnetic Ising model within an oscillating magnetic field. They employed dynamic mean-field calculations to find the dynamic phase transition temperatures, the dynamic compensation points of the model and to present the dynamic phase diagrams. In this work, we extend the study and investigate the dynamic hysteresis behaviors for the two-dimensional (2D) mixed spin (2, 5/2) ferrimagnetic Ising model on a hexagonal lattice in an oscillating magnetic field within the framework of dynamic mean-field calculations. The dynamic hysteresis curves are obtained for both the ferromagnetic and antiferromagnetic interactions and the effects of the Hamiltonian parameters on the dynamic hysteresis behaviors are discussed in detail. The thermal behaviors of the coercivity and remanent magnetizations are also investigated. The results are compared with some theoretical and experimental works and a qualitatively good agreement is found. Finally, the dynamic phase diagrams depending on the frequency of an oscillating magnetic field in the plane of the reduced temperature versus magnetic field amplitude is examined and it is found that the dynamic phase diagrams display richer dynamic critical behavior for higher values of frequency than for lower values.

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

    NASA Astrophysics Data System (ADS)

    Akbarabadi, Morteza; Piri, Mohammad

    2013-02-01

    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.

  20. Wavenumber selection and hysteresis in nonlinear baroclinic flow

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung

    1995-01-01

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

  1. A theory of triple hysteresis in ferroelectric crystals

    NASA Astrophysics Data System (ADS)

    Weng, George J.

    2009-10-01

    In the vicinity of the transition temperature between two ferroelectric states, a ferroelectric crystal could exhibit a triple hysteresis under an ac field. For a BaTiO3 with the "c-plate" configuration slightly below this temperature, the middle loop is caused by the 0°?180° domain switch in the orthorhombic phase, whereas the upper and lower loops are the result of orthorhombic-to-tetragonal phase transition, and vice versa. In this article we first develop a micromechanics-based thermodynamic model to determine the thermodynamic driving force for phase transition and for domain switch as a function of electric field and temperature, and in the latter case, further supplement it with a kinetic equation and a homogenization scheme. The dependence of dielectric constant of the orthorhombic and tetragonal phases on temperature and electric field are also established. The developed theory is then applied to calculate the triple hysteresis loops of BaTiO3 at several levels of temperature. The calculated results for the triple loops, and for the variation of dielectric constant, are found to be in full accord with the test data of Huibregtse and Young [Phys. Rev. 103, 1705 (1956)].

  2. Inelastic compaction, dilation and hysteresis of sandstones under hydrostatic conditions

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  3. Characterization upon electrical hysteresis and thermal diffusion of TiAl3Ox dielectric film

    PubMed Central

    2011-01-01

    In this paper, we have investigated the electrical properties of TiAl3Ox 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 TiAl3Ox/Si interfacial region in detail. The TiAl3Ox films show obvious electrical hysteresis by the capacitance-voltage measurements after post-annealing treatment. By virtue of the diffusion models composed of TiAl3Ox 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. PMID:22011364

  4. Magnetic biasing of a ferroelectric hysteresis loop in a multiferroic orthoferrite.

    PubMed

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

    2014-01-24

    In a multiferroic orthoferrite Dy0.7Tb0.3FeO3, which shows electric-field-(E-)driven magnetization (M) reversal due to a tight clamping between polarization (P) and M, a gigantic effect of magnetic-field (H) biasing on P-E hysteresis loops is observed in the case of rapid E sweeping. The magnitude of the bias E field can be controlled by varying the magnitude of H, and its sign can be reversed by changing the sign of H or the relative clamping direction between P and M. The origin of this unconventional biasing effect is ascribed to the difference in the Zeeman energy between the +P and -P states coupled with the M states with opposite sign. PMID:24484164

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

    PubMed Central

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

    2014-01-01

    The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25?cm2 active area create a serpentine flow-field on an active area of 100?cm2 and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums. PMID:24699531

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

    SciTech Connect

    Yang, Z.J.; Hull, J.R.; Mulcahy, T.M.; Rossing, T.D.

    1995-08-01

    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}.

  7. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of ?-iron containing nonmagnetic particles

    SciTech Connect

    Li, Yi; Xu, Ben; Hu, Shenyang; Li, Yulan; Li, Qiulin; Liu, Wei

    2015-07-01

    The magnetic hysteresis loops and Barkhausen noise of a single ?-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  8. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of ?-iron containing nonmagnetic particles

    DOE PAGESBeta

    Li, Yi; Xu, Ben; Hu, Shenyang; Li, Yulan; Li, Qiulin; Liu, Wei

    2015-07-01

    The magnetic hysteresis loops and Barkhausen noise of a single ?-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domainsmore »on the magnetization reversal behavior and the magnetic properties.« less

  9. Hysteresis Modeling and Inverse Feedforward Control of an AFM Piezoelectric Scanner Based on Nano Images

    E-print Network

    Li, Yangmin

    Hysteresis Modeling and Inverse Feedforward Control of an AFM Piezoelectric Scanner Based on Nano of micro/nano technology. As a critical part of AFM system, the piezoelectric scanner exists many defects in this paper possess a good performance for AFM nano imaging. Index Terms-- Hysteresis modeling, feedforward

  10. Large melting point hysteresis of Ge nanocrystals embedded inSiO2

    SciTech Connect

    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

    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.

  11. Adsorption hysteresis in nanopores Alexander V. Neimark,* Peter I. Ravikovitch, and Aleksey Vishnyakov

    E-print Network

    Muzzio, Fernando J.

    Adsorption hysteresis in nanopores Alexander V. Neimark,* Peter I. Ravikovitch, and Aleksey the modeling results and the experimental hysteresis loops formed by the adsorption-desorption isotherms- ized by a typical step in adsorption isotherms and, in the vast majority of systems, is associated

  12. Fig. 1. Magnetic hysteresis of NiO-doped NiF2 conversion materials

    E-print Network

    Siegel, Paul H.

    Fig. 1. Magnetic hysteresis of NiO-doped NiF2 conversion materials CMRR Newsletter Shirley Meng). We have investigated the NiF2 based conversion materials and the conversion reaction includes becomes superparamagnetic. The distinguishable magnetic hysteresis was observed at 5K since NiF2

  13. Comment on ``Large Melting-Point Hysteresis of Ge Nanocrystals Embedded in SiO2''

    E-print Network

    Caupin, Frédéric

    Comment on ``Large Melting-Point Hysteresis of Ge Nanocrystals Embedded in SiO2'' In their Letter melting-point hysteresis around the bulk melting point Tm is used with classical nucleation theory (CNT [1], Xu et al. study the melting behavior of Ge nanocrystals (NC) in a SiO2 matrix. The observed

  14. PHYSICAL REVIEW E 90, 042103 (2014) Avalanches and hysteresis in frustrated superconductors and XY spin glasses

    E-print Network

    Müller, Markus

    2014-01-01

    PHYSICAL REVIEW E 90, 042103 (2014) Avalanches and hysteresis in frustrated superconductors and XY October 2014) We study avalanches along the hysteresis loop of long-range interacting spin glasses becoming unstable, which induces an avalanche of phase updates (or spin alignments). We analyze

  15. A Domain Wall Model for Ferroelectric Hysteresis Ralph C. Smith 1 and Craig L. Hom 2

    E-print Network

    of these materials in high performance actuator design. The nature of hysteresis models for ferroelectric materials as the polycrystalline nature of the materials. Moreover, microscopic models are often difficult to employ in control a mathematical model for characterizing hysteresis in ferroelectric materials. The model is based

  16. A Domain Wall Model for Ferroelectric Hysteresis Ralph C. Smith1 and Craig L. Hom2

    E-print Network

    of these materials in high performance actuator design. The nature of hysteresis models for ferroelectric materials as the polycrystalline nature of the materials. Moreover, microscopic models are often di cult to employ in control a mathematical model for characterizing hysteresis in ferroelectric materials. The model is based on the quanti

  17. Mechanisms of exercise-recovery hysteresis in the ECG: ISCE 2015 paper.

    PubMed

    Swenne, Cees A

    2015-01-01

    This paper gives an overview of multiple factors, like the mechanisms governing rate adaptation of ventricular action potentials and autonomic mechanisms, which play a role in the genesis of exercise-recovery hysteresis in the ECG. It also discusses the possible association between exercise-recovery ECG hysteresis and arrhythmogeneity. PMID:26336871

  18. An air-cooled Litz wire coil for measuring the high frequency hysteresis loops of magnetic samples : a useful setup for magnetic hyperthermia applications

    E-print Network

    Connord, V; Tan, R P; Carrey, J; Respaud, M

    2014-01-01

    A low-cost and simple setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An AMF in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of MNPs for magnetic hyperthermia applications.

  19. An air-cooled Litz wire coil for measuring the high frequency hysteresis loops of magnetic samples—A useful setup for magnetic hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Connord, V.; Mehdaoui, B.; Tan, R. P.; Carrey, J.; Respaud, M.

    2014-09-01

    A setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An alternating magnetic field in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops, and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of magnetic nanoparticles for magnetic hyperthermia applications.

  20. Hysteresis in the Cell Response to Time-Dependent Substrate Stiffness Achim Besser and Ulrich S. Schwarz*

    E-print Network

    Schwarz, Ulrich

    Hysteresis in the Cell Response to Time-Dependent Substrate Stiffness Achim Besser and Ulrich S predict that rate- dependent hysteresis will occur in the cellular traction forces when cells are exposed

  1. The Art Show

    ERIC Educational Resources Information Center

    Scolarici, Alicia

    2004-01-01

    This article describes what once was thought to be impossible--a formal art show extravaganza at an elementary school with 1,000 students, a Department of Defense Dependent School (DODDS) located overseas, on RAF Lakenheath, England. The dream of this this event involved the transformation of the school cafeteria into an elegant art show

  2. MCMC curve sampling for image segmentation.

    PubMed

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

    2007-01-01

    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

  3. A kill curve for Phanerozoic marine species

    NASA Technical Reports Server (NTRS)

    Raup, D. M.

    1991-01-01

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

  4. Dissociative Recombination without a Curve Crossing

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1994-01-01

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

  5. Measuring Model Rocket Engine Thrust Curves

    ERIC Educational Resources Information Center

    Penn, Kim; Slaton, William V.

    2010-01-01

    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…

  6. A Holographic Road Show.

    ERIC Educational Resources Information Center

    Kirkpatrick, Larry D.; Rugheimer, Mac

    1979-01-01

    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)

  7. Hysteresis in coral reefs under macroalgal toxicity and overfishing.

    PubMed

    Bhattacharyya, Joydeb; Pal, Samares

    2015-03-01

    Macroalgae and corals compete for the available space in coral reef ecosystems.While herbivorous reef fish play a beneficial role in decreasing the growth of macroalgae, macroalgal toxicity and overfishing of herbivores leads to proliferation of macroalgae. The abundance of macroalgae changes the community structure towards a macroalgae-dominated reef ecosystem. We investigate coral-macroalgal phase shifts by means of a continuous time model in a food chain. Conditions for local asymptotic stability of steady states are derived. It is observed that in the presence of macroalgal toxicity and overfishing, the system exhibits hysteresis through saddle-node bifurcation and transcritical bifurcation. We examine the effects of time lags in the liberation of toxins by macroalgae and the recovery of algal turf in response to grazing of herbivores on macroalgae by performing equilibrium and stability analyses of delay-differential forms of the ODE model. Computer simulations have been carried out to illustrate the different analytical results. PMID:25708511

  8. Bouc-Wen hysteresis model identification using Modified Firefly Algorithm

    NASA Astrophysics Data System (ADS)

    Zaman, Mohammad Asif; Sikder, Urmita

    2015-12-01

    The parameters of Bouc-Wen hysteresis model are identified using a Modified Firefly Algorithm. The proposed algorithm uses dynamic process control parameters to improve its performance. The algorithm is used to find the model parameter values that results in the least amount of error between a set of given data points and points obtained from the Bouc-Wen model. The performance of the algorithm is compared with the performance of conventional Firefly Algorithm, Genetic Algorithm and Differential Evolution algorithm in terms of convergence rate and accuracy. Compared to the other three optimization algorithms, the proposed algorithm is found to have good convergence rate with high degree of accuracy in identifying Bouc-Wen model parameters. Finally, the proposed method is used to find the Bouc-Wen model parameters from experimental data. The obtained model is found to be in good agreement with measured data.

  9. The thermodynamic origin of hysteresis in insertion batteries.

    PubMed

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

    2010-05-01

    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

  10. Cumulative growth of minor hysteresis loops in the Kolmogorov model

    SciTech Connect

    Meilikhov, E. Z. Farzetdinova, R. M.

    2013-01-15

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

  11. Phase transition and hysteresis in scale-free network traffic

    NASA Astrophysics Data System (ADS)

    Hu, Mao-Bin; Wang, Wen-Xu; Jiang, Rui; Wu, Qing-Song; Wu, Yong-Hong

    2007-03-01

    We model information traffic on scale-free networks by introducing the node queue length L proportional to the node degree and its delivering ability C proportional to L . The simulation gives the overall capacity of the traffic system, which is quantified by a phase transition from free flow to congestion. It is found that the maximal capacity of the system results from the case of the local routing coefficient ? slightly larger than zero, and we provide an analysis for the optimal value of ? . In addition, we report for the first time the fundamental diagram of flow against density, in which hysteresis is found, and thus we can classify the traffic flow with four states: free flow, saturated flow, bistable, and jammed.

  12. Hysteresis in Magnetic Shape Memory Composites: Modeling and Simulation

    E-print Network

    Conti, Sergio; Rumpf, Martin

    2015-01-01

    Magnetic shape memory alloys are characterized by the coupling between a structural phase transition and magnetic one. This permits to control the shape change via an external magnetic field, at least in single crystals. Composite materials with single-crystalline particles embedded in a softer matrix have been proposed as a way to overcome the blocking of the transformation at grain boundaries. We investigate hysteresis phenomena for small NiMnGa single crystals embedded in a polymer matrix for slowly varying magnetic fields. The evolution of the microstructure is studied within the rate-independent variational framework proposed by Mielke and Theil (1999). The underlying variational model incorporates linearized elasticity, micromagnetism, stray field and a dissipation term proportional to the volume swept by the phase boundary. The time discretization is based on an incremental minimization of the sum of energy and dissipation. A backtracking approach is employed to approximately ensure the global minimali...

  13. Geomorphological origin of recession curves

    NASA Astrophysics Data System (ADS)

    Biswal, Basudev; Marani, Marco

    2010-12-01

    We identify a previously undetected link between the river network morphology and key recession curves properties through a conceptual-physical model of the drainage process of the riparian unconfined aquifer. We show that the power-law exponent, ?, of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. Using Digital Terrain Models and daily discharge observations from 67 US basins we find that geomorphologic ? estimates match well the values obtained from recession curves analyses. Finally, we argue that the link between recession flows and network morphology points to an important role of low-flow discharges in shaping the channel network.

  14. Inside the hysteresis loop: Multiplicity of internal states in confined fluids Alexander V. Neimark,* Peter I. Ravikovitch, and Aleksey Vishnyakov

    E-print Network

    Muzzio, Fernando J.

    Inside the hysteresis loop: Multiplicity of internal states in confined fluids Alexander V. Neimark of metastable states and capillary condensation hysteresis of a Lennard-Jones fluid in cylindrical pores inside the hysteresis loop. The region of multiple states is bounded by the states of zero

  15. A Unified Model for Hysteresis in Ferroic Materials Ralph C. Smith # , Stefan Seelecke + , Marcelo J. Dapino # , and Zoubeida Ounaies

    E-print Network

    A Unified Model for Hysteresis in Ferroic Materials Ralph C. Smith # , Stefan Seelecke + , Marcelo in hysteretic and nonlinear regimes. Whereas the physical mechanisms which produce hysteresis and constitutive. This unified methodology for quantifying hysteresis and constitutive nonlinearities for a broad class

  16. Instanton Analysis of Hysteresis in the Three-Dimensional Random-Field Ising Model Markus Muller and Alessandro Silva

    E-print Network

    Müller, Markus

    Instanton Analysis of Hysteresis in the Three-Dimensional Random-Field Ising Model Markus Mu hysteresis in the random-field Ising model in 3D. We discuss the disorder dependence of the coercive field Hc, and obtain an analytical description of the smooth part of the hysteresis below and above Hc, by identifying

  17. LLS and FTIR Studies on the Hysteresis in Association and Dissociation of Poly(N-isopropylacrylamide) Chains in Water

    E-print Network

    Wu, Chi

    LLS and FTIR Studies on the Hysteresis in Association and Dissociation of Poly aqueous solutions. There exists a hysteresis in the temperature dependence of the average hydrodynamic. Therefore, the chain contraction is entropy-driven, and the hysteresis can be attributed to these additional

  18. Adaptive feed-forward hysteresis compensation for piezoelectric actuators Arnfinn Aas Eielsen, Jan Tommy Gravdahl, and Kristin Y. Pettersen

    E-print Network

    Gravdahl, Jan Tommy

    Adaptive feed-forward hysteresis compensation for piezoelectric actuators Arnfinn Aas Eielsen, Jan) Adaptive feed-forward hysteresis compensation for piezoelectric actuators Arnfinn Aas Eielsen,a) Jan Tommy. Hysteresis and creep nonlinearities inherent in such actuators deteriorate positioning accuracy. An online

  19. Steps in the hysteresis loops of a high-spin molecule Jonathan R. Friedman and M. P. Sarachik

    E-print Network

    Friedman, Jonathan R.

    Steps in the hysteresis loops of a high-spin molecule Jonathan R. Friedman and M. P. Sarachik Corporation, Webster, New York 14580 We report the first observation of steps in the hysteresis loop of a high of 3 K, hysteresis is observed3,5 and slow exponential relaxation of the magneti- zation has been found

  20. 1096 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 3, MARCH 2006 Analysis and Elimination of Hysteresis and

    E-print Network

    Rutledge, David B.

    and Elimination of Hysteresis and Noisy Precursors in Power Amplifiers Sanggeun Jeon, Student Member, IEEE, the anomalous behavior observed in a Class-E PA is analyzed in detail. It involves hysteresis in the power required the development of a new technique for the elimination of the hysteresis. Instead of a trial

  1. Global Sliding Mode-Based Tracking Control of a Piezo-Driven XY Micropositioning Stage with Unmodeled Hysteresis

    E-print Network

    Li, Yangmin

    with Unmodeled Hysteresis Qingsong Xu and Yangmin Li, Senior Member, IEEE Abstract-- In this paper, a global that the GSMC can reduce the hysteresis to a negligible level and lead to a sub-micron accuracy tracking- driven stages comes from the nonlinearities introduced by PZT attributed to the hysteresis, creep

  2. Reduction of Major and Minor Hysteresis Loops in a Piezoelectric Juan Manuel Cruz-Hernandez and Vincent Hayward

    E-print Network

    Hayward, Vincent

    Reduction of Major and Minor Hysteresis Loops in a Piezoelectric Actuator Juan Manuel Cruz and minor hysteresis loops using an operator termed a phaser which shifts the phase of a periodic signal by an amount . For periodic inputs, hysteresis can be approximated by a phaser with a negative phase shift

  3. A Dynamic Hysteresis Model for THUNDER Transducers Brian L. Ball 1 , Ralph C. Smith 2 and Zoubeida Ounaies 3

    E-print Network

    A Dynamic Hysteresis Model for THUNDER Transducers Brian L. Ball 1 , Ralph C. Smith 2 and Zoubeida to the piezoceramic patch. A free energy based hysteretic stress­strain relation is employed to model hysteresis: THUNDER actuators, displacement model, hysteresis, piezoceramic, transition element, polariza­ tion

  4. 456 IEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 14, NO. 4, AUGUST 2009 Disturbance-Observer-Based Hysteresis

    E-print Network

    Yi, Jingang

    -Observer-Based Hysteresis Compensation for Piezoelectric Actuators Jingang Yi, Senior Member, IEEE, Steven Chang, and Yantao Shen, Member, IEEE Abstract--We present a novel hysteresis compensation method for piezoelectric actuators. We consider the hysteresis nonlinearity of the actuator as a disturbance over a linear system

  5. Construction of hysteresis loops of single domain elements and coupled permalloy ring arrays by magnetic force microscopy

    E-print Network

    Grütter, Peter

    Construction of hysteresis loops of single domain elements and coupled permalloy ring arrays, the hysteresis loop is constructed by counting the percentage of switched elements imaged at remanence. Their hysteresis loop is obtained by MFM imaging at a field between the switching fields of these two states

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

    NASA Astrophysics Data System (ADS)

    Liu, Xueming

    2010-02-01

    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.

  7. Approach to saturation analysis of hysteresis measurements in rock magnetism and evidence for stress dominated magnetic anisotropy in young mid-ocean ridge basalt

    NASA Astrophysics Data System (ADS)

    Fabian, Karl

    2006-03-01

    Young mid-ocean ridge basalts contain titanomagnetite crystals of varying size and composition. Many studies of their hysteresis properties have found M/M ratios considerably above the theoretical limit of 0.5 for uniaxial single domain particles. Since titanomagnetite is a cubic mineral, high M/M could occur due to cubic anisotropy which allows for M/M values up to 0.866. On the other hand, titanomagnetites with high Ti content possess extremely large magnetostriction constants. Already slight internal stress easily outweighs cubic anisotropy and enforces uniaxial behavior. Are high M/M ratios now a proof for very low internal stress? No! On the contrary, previous studies on synthetic titanomagnetite with high M/M show that after annealing this ratio decreases. A possible explanation is that insufficient saturation of the hysteresis loop, used to infer M/M, leads to underestimation of M. Here, a systematic experimental study on a young mid-ocean ridge basalt using fields of up to 7 T demonstrates that indeed the M/M ratio of the single domain fraction does not significantly deviate from the theoretical value of 0.5 for uniaxial anisotropy. It is further estimated that internal stress above 200 MPa is necessary to explain the observed hysteresis behavior - a value which is consistent with recent independent approximations. On the other hand, theoretical loops for cubic minerals do not fit the observed data. In order to assess the validity of M determinations from hysteresis measurements, an improved method to evaluate the approach to saturation behavior of hysteresis loops is developed. It allows to recognize insufficiently saturated loops and thereby helps to avoid misinterpretation of standard M/M measurements when high fields are not accessible.

  8. Show Me the Way

    ERIC Educational Resources Information Center

    Dicks, Matthew J.

    2005-01-01

    Because today's students have grown up steeped in video games and the Internet, most of them expect feedback, and usually gratification, very soon after they expend effort on a task. Teachers can get quick feedback to students by showing them videotapes of their learning performances. The author, a 3rd grade teacher describes how the seemingly…

  9. Stage a Water Show

    ERIC Educational Resources Information Center

    Frasier, Debra

    2008-01-01

    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…

  10. Showing What They Know

    ERIC Educational Resources Information Center

    Cech, Scott J.

    2008-01-01

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

  11. Obesity in show cats.

    PubMed

    Corbee, R J

    2014-12-01

    Obesity is an important disease with a high prevalence in cats. Because obesity is related to several other diseases, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain cat breeds has been suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, 268 cats of 22 different breeds investigated by determining their body condition score (BCS) on a nine-point scale by inspection and palpation, at two different cat shows. Overall, 45.5% of the show cats had a BCS > 5, and 4.5% of the show cats had a BCS > 7. There were significant differences between breeds, which could be related to the breed standards. Most overweight and obese cats were in the neutered group. It warrants firm discussions with breeders and cat show judges to come to different interpretations of the standards in order to prevent overweight conditions in certain breeds from being the standard of beauty. Neutering predisposes for obesity and requires early nutritional intervention to prevent obese conditions. PMID:24612018

  12. The Ozone Show.

    ERIC Educational Resources Information Center

    Mathieu, Aaron

    2000-01-01

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

  13. Holomorphic curves in surfaces of general type.

    PubMed Central

    Lu, S S; Yau, S T

    1990-01-01

    This note answers some questions on holomorphic curves and their distribution in an algebraic surface of positive index. More specifically, we exploit the existence of natural negatively curved "pseudo-Finsler" metrics on a surface S of general type whose Chern numbers satisfy c(2)1>2c2 to show that a holomorphic map of a Riemann surface to S whose image is not in any rational or elliptic curve must satisfy a distance decreasing property with respect to these metrics. We show as a consequence that such a map extends over isolated punctures. So assuming that the Riemann surface is obtained from a compact one of genus q by removing a finite number of points, then the map is actually algebraic and defines a compact holomorphic curve in S. Furthermore, the degree of the curve with respect to a fixed polarization is shown to be bounded above by a multiple of q - 1 irrespective of the map. PMID:11607050

  14. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  15. The Skipping Rope Curve

    ERIC Educational Resources Information Center

    Nordmark, Arne; Essen, Hanno

    2007-01-01

    The equilibrium of a flexible inextensible string, or chain, in the centrifugal force field of a rotating reference frame is investigated. It is assumed that the end points are fixed on the rotation axis. The shape of the curve, the skipping rope curve or "troposkien", is given by the Jacobi elliptic function sn. (Contains 3 figures.)

  16. Mars Slide Show

    NASA Technical Reports Server (NTRS)

    2006-01-01

    15 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a landslide that occurred off of a steep slope in Tithonium Chasma, part of the vast Valles Marineris trough system.

    Location near: 4.8oS, 84.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  17. Keeping Show Pigs Healthy 

    E-print Network

    Lawhorn, D. Bruce

    2006-10-13

    ? are approved antibiotics commonly used in rations. For more information on feed med- ication for specific diseases, check these Extension publications: Diarrheal Disease in Show Swine, L-5320; and Swine Pneumonia, L-5203. taking care dUring and after... requiring anesthesia, such as removal of a retained testicle (cryptorchidism), removal of an infected and enlarged urine pocket (preputial diverticulum removal), repair of scrotal or umbil- ical hernia, and removal of tumors. Before a sur- geon...

  18. Implications of NiMH Hysteresis on HEV Battery Testing and Performance

    SciTech Connect

    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

    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.

  19. Molecular thermal hysteresis in helix-dimer formation of sulfonamidohelicene oligomers in solution.

    PubMed

    Shigeno, Masanori; Kushida, Yo; Yamaguchi, Masahiko

    2013-07-29

    Sulfonamidohelicene oligomers up to the nonamer level were synthesized by the repeated coupling reactions of a building block. A tetramer formed a helix dimer in 1,3-difluorobenzene, which unfolded to a random coil with heating. This structural change exhibited thermal hysteresis in which different thermal responses were observed in the course of temperature increase and decrease. The feature of the hysteresis was examined under different heating/cooling modes, and the mechanisms are discussed on the basis of the population change and the presence of an induction period. A proposal regarding the use of thermal hysteresis for sensing a temperature increase/decrease is also given. PMID:23775763

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

    NASA Astrophysics Data System (ADS)

    Zvizdi?, D.; Šestan, D.

    2013-09-01

    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.

  1. Feedback/feedforward control of hysteresis-compensated piezoelectric actuators for high-speed scanning applications

    NASA Astrophysics Data System (ADS)

    Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich

    2015-01-01

    This paper presents the control system design for a piezoelectric actuator (PEA) for a high-speed trajectory scanning application. First nonlinear hysteresis is compensated for by using the Maxwell resistive capacitor model. Then the linear dynamics of the hysteresis-compensated piezoelectric actuator are identified. A proportional plus integral (PI) controller is designed based on the linear system, enhanced by feedforward hysteresis compensation. It is found that the feedback controller does not always improve tracking accuracy. When the input frequency exceeds a certain value, feedforward control only may result in better control performance. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  2. Unwrapping Closed Timelike Curves

    E-print Network

    Sergei Slobodov

    2008-08-07

    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 change its topology, without changing its geometry, in such a way that the former CTCs are no longer closed in the new spacetime. This 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 give two examples of unwrapping of essentially 2+1 dimensional spacetimes with CTCs, the Gott spacetime and the Godel universe. We show that the unwrapped Gott spacetime, while singular, is at least devoid of CTCs. In contrast, the unwrapped Godel 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 two spacetimes we investigated, CTCs appearing in the solutions of the Einstein equation are not simply a mathematical artifact of coordinate identifications, but are indeed a necessary consequence of General Relativity, provided only that we demand these solutions do not possess naked quasi-regular singularities.

  3. On the 2D-transition, hysteresis and thermodynamic equilibrium of Kr adsorption on a graphite surface.

    PubMed

    Diao, Rui; Fan, Chunyan; Do, D D; Nicholson, D

    2015-12-15

    The adsorption and desorption of Kr on graphite at temperatures in the range 60-88K, was systematically investigated using a combination of several simulation techniques including: Grand Canonical Monte Carlo (GCMC), Canonical kinetic-Monte Carlo (C-kMC) and the Mid-Density Scheme (MDS). Particular emphasis was placed on the gas-solid, gas-liquid and liquid-solid 2D phase transitions. For temperatures below the bulk triple point, the transition from a 2D-liquid-like monolayer to a 2D-solid-like state is manifested as a sub-step in the isotherm. A further increase in the chemical potential leads to another rearrangement of the 2D-solid-like state from a disordered structure to an ordered structure that is signalled by (1) another sub-step in the monolayer region and (2) a spike in the plot of the isosteric heat versus density at loadings close to the dense monolayer coverage concentration. Whenever a 2D transition occurs in a grand canonical isotherm it is always associated with a hysteresis, a feature that is not widely recognised in the literature. We studied in details this hysteresis with the analysis of the canonical isotherm, obtained with C-kMC, which exhibits a van der Waals (vdW) type loop with a vertical segment in the middle. We complemented the hysteresis loop and the vdW curve with the analysis of the equilibrium transition obtained with the MDS, and found that the equilibrium transition coincides exactly with the vertical segment of the C-kMC isotherm, indicating the co-existence of two phases at equilibrium. We also analysed adsorption at higher layers and found that the 2D-coexistence is also observed, provided that the temperature is well below the triple point. Finally the 2D-critical temperatures were obtained for the first three layers and they are in good agreement with the experimental data in the literature. PMID:26364074

  4. Public medical shows.

    PubMed

    Walusinski, Olivier

    2014-01-01

    In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre. PMID:25273491

  5. Btu accounting: Showing results

    SciTech Connect

    Nelson, K.E.

    1994-10-01

    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. Energy-consumption reporting is particularly valuable when viewed over a period of time. The author recommend compiling data annually and maintaining a ten-year performance history. Four cases are considered: individual plant performance; site performance for sites having more than one plant; company performance, for companies having more than one site; and performance based on product, for identical or similar products made at different plants or sites. Of these, individual plant performance is inherently the most useful. It also serves as the best basis for site, company and product performance reports. A key element in energy accounting is the relating of all energy consumption to a common basis. As developed last month in Part 1 in this series, the author chose Btu[sub meth] (i.e., Btu of methane equivalent, expressed as its higher heating value) for this purpose. It represents the amount of methane that would be needed to replace (in the case of fuels) or generate (in the case of steam and power) the energy being used.

  6. Hysteresis and bistability in the direct transition from 1:1 to 2:1 rhythm in periodically driven single ventricular cells

    E-print Network

    Guevara, Michael R.

    Hysteresis and bistability in the direct transition from 1:1 to 2:1 rhythm in periodically driven, demonstrating hysteresis. With the BCL set to a value within the hysteresis range, injection of a single well . Hysteresis between 1:1 and 2:1 rhythms was also seen when the stimulus amplitude, rather than the BCL

  7. Generating artificial light curves: Revisited and updated

    E-print Network

    Emmanoulopoulos, D; Papadakis, I E

    2013-01-01

    The production of artificial light curves with known statistical and variability properties is of great importance in astrophysics. Consolidating the confidence levels during cross-correlation studies, understanding the artefacts induced by sampling irregularities, establishing detection limits for future observatories are just some of the applications of simulated data sets. Currently, the widely used methodology of amplitude and phase randomisation is able to produce artificial light curves which have a given underlying power spectral density (PSD) but which are strictly Gaussian distributed. This restriction is a significant limitation, since the majority of the light curves e.g. active galactic nuclei, X-ray binaries, gamma-ray bursts show strong deviations from Gaussianity exhibiting `burst-like' events in their light curves yielding long-tailed probability distribution functions (PDFs). In this study we propose a simple method which is able to precisely reproduce light curves which match both the PSD an...

  8. Crude oil supply curves

    E-print Network

    Adelman, Morris Albert

    1998-01-01

    Short-run cost curves shift over time as depletion counters increasing knowledge. Under competition, a rightward (leftward) shift indicates lower (higher) cost and greater (lesser) productivity. A simple coefficient captures ...

  9. The Great Cometary Show

    NASA Astrophysics Data System (ADS)

    2007-01-01

    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

  10. Seasonal variation in phosphorus concentration-discharge hysteresis inferred from high-frequency in situ monitoring

    NASA Astrophysics Data System (ADS)

    Bieroza, M. Z.; Heathwaite, A. L.

    2015-05-01

    High-resolution in situ total phosphorus (TP), total reactive phosphorus (TRP) and turbidity (TURB) time series are presented for a groundwater-dominated agricultural catchment. Meta-analysis of concentration-discharge (c-q) intra-storm signatures for 61 storm events revealed dominant hysteretic patterns with similar frequency of anti-clockwise and clockwise responses; different determinands (TP, TRP, TURB) behaved similarly. We found that the c-q loop direction is controlled by seasonally variable flow discharge and temperature whereas the magnitude is controlled by antecedent rainfall. Anti-clockwise storm events showed lower flow discharge and higher temperature compared to clockwise events. Hydrological controls were more important for clockwise events and TP and TURB responses, whereas in-stream biogeochemical controls were important for anti-clockwise storm events and TRP responses. Based on the best predictors of the direction of the hysteresis loops, we calibrated and validated a simple fuzzy logic inference model (FIS) to determine likely direction of the c-q responses. We show that seasonal and inter-storm succession in clockwise and anti-clockwise responses corroborates the transition in P transport from a chemostatic to an episodic regime. Our work delivers new insights for the evidence base on the complexity of phosphorus dynamics. We show the critical value of high-frequency in situ observations in advancing understanding of freshwater biogeochemical processes.

  11. Multi-View 3D Shape and Motion Recovery on the Spatio-Temporal Curve Manifold

    E-print Network

    Toronto, University of

    -Temporal Curve Manifold that describes the curve's trace in space-time, and (2) a local analytical description-Temporal Curve Manifold, which is the trace of a moving 3D curve in space-time. We show that com- putingMulti-View 3D Shape and Motion Recovery on the Spatio-Temporal Curve Manifold Rodrigo L. Carceroni

  12. Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

    E-print Network

    Pinson, Matthew B.

    Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations ...

  13. Magnetic structure and hysteresis in hard magnetic nanocrystalline film: Computer simulation

    E-print Network

    Laughlin, David E.

    Magnetic structure and hysteresis in hard magnetic nanocrystalline film: Computer simulation simulations are used to study the effect of crystallographic textures on the magnetic properties of uniaxial nanocrystalline films of hard magnetic materials with arbitrary grain shapes and size distributions

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    The temperature hysteresis phenomenon of a Loop Heat Pipe (LHP) was experimentally investigated. The temperature hysteresis was identified by the fact that the operating temperature depends upon not only the imposed power but also the previous history of the power variation. The temperature hysteresis could impose limitations on the LHP applications since the LHP may exhibit different steady-state operating temperatures at a given power input even when the condenser sink temperature remains unchanged. In order to obtain insight to this phenomenon, a LHP was tested at different elevations and tilts by using an elaborated power profile. A hypothesis was suggested to explain the temperature hysteresis. This hypothesis explains well the experimental observations. Results of this study provide a better understanding of the performance characteristics of the LHPS.

  15. Theory of sorption hysteresis in nanoporous solids: Part II Molecular condensation

    E-print Network

    Bazant, Martin Z.

    Motivated by the puzzle of sorption hysteresis in Portland cement concrete or cement paste, we develop in Part II of this study a general theory of vapor sorption and desorption from nanoporous solids, which attributes ...

  16. Theory of sorption hysteresis in nanoporous solids: Part I Snap-through instabilities

    E-print Network

    Bazant, Martin Z.

    The sorption–desorption hysteresis observed in many nanoporous solids, at vapor pressures low enough for the liquid (capillary) phase of the adsorbate to be absent, has long been vaguely attributed to some sort of ‘pore ...

  17. "Universal" Recession Curves and their Geomorphological Roots

    NASA Astrophysics Data System (ADS)

    Marani, M.; Biswal, B.

    2011-12-01

    The basic structural organization of channel networks, and of the connected hillslopes, have been shown to be intimately linked to basin responses to rainfall events, leading to geomorphological theories of the hydrologic response. Here, We identify a previously undetected link between the river network morphology and key recession curves properties. We show that the power-law exponent of -dQ/dt vs. Q curves is related to the power-law exponent of N(l) vs. G(l) curves (which we show to be connected to Hack's law), where l is the downstream distance from the channel heads, N(l) is the number of channel reaches exactly located at a distance l from their channel head, and G(l) is the total length of the network located at a distance greater or equal to l from channel heads. We then generalize the power-law expressions of recession curves, to identify "universal" curves, independent of the initial moisture conditions and of basin area, by making the -dQ/dt vs. Q curve non-dimensional using an index discharge representative of initial moisture conditions. We subsequently rescale the geomorphic recession curve, N(l) vs. G(l), producing a collapse of the geomorphic recession curves constructed from the DTM's of 67 US study basins. Finally, by use of the specific discharge u = Q/A, we link the two previous results and define the specific recession curves, whose collapse across basins within homogeneous geographical areas lends further, decisive, support to the notion that the statistical properties of observational recession curves bear the signature of the geomorphological structure of the networks producing them.

  18. Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Hernández-Gómez, P.; Muñoz, J. M.; Valente, M. A.; Torres, C.; de Francisco, C.

    2013-01-01

    Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer's formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

  19. Does Corneal Hysteresis Correlate with Endothelial Cell Density?

    PubMed Central

    Akova-Budak, Berna; K?vanç, Sertaç Argun

    2015-01-01

    Background Our aim was to determine if there is a correlation between corneal biomechanical properties, endothelial cell count, and corneal pachymetry in healthy corneas. Material/Methods Ninety-two eyes of all subjects underwent complete ocular examination, including intraocular pressure measurement by Goldmann applanation tonometer, objective refraction, and slit-lamp biomicroscopy. Topographic measurements and corneal pachymetry were performed using a Scheimpflug-based (Pentacam, Oculus, Germany) corneal topographer. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with an Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, NY). Endothelial cell count measurement was done using a specular microscope (CellChek, Konan, USA). Results Right eye values of the subjects were taken for the study. The mean CH was 11.5±1.7 mmHg and the mean CRF was 11.2±1.4 mmHg. Mean intraocular pressure was 15.3±2.3 mmHg. The mean endothelial cell count was 2754±205 cells/mm2. No correlation was found between biomechanical properties of cornea and endothelial cell count. There was a significant positive correlation between CH, CRF, and corneal thickness (p<0.001; r=0.79). Conclusions The corneal biomechanical properties significantly correlated with corneal thickness. We found no correlation between CH and CRF with the endothelial cell density in normal subjects. PMID:25994302

  20. The Dynamic Characteristic and Hysteresis Effect of an Air Spring

    NASA Astrophysics Data System (ADS)

    Löcken, F.; Welsch, M.

    2015-02-01

    In many applications of vibration technology, especially in chassis, air springs present a common alternative to steel spring concepts. A design-independent and therefore universal approach is presented to describe the dynamic characteristic of such springs. Differential and constitutive equations based on energy balances of the enclosed volume and the mountings are given to describe the nonlinear and dynamic characteristics. Therefore all parameters can be estimated directly from physical and geometrical properties, without parameter fitting. The numerically solved equations fit very well to measurements of a passenger car air spring. In a second step a simplification of this model leads to a pure mechanical equation. While in principle the same parameters are used, just an empirical correction of the effective heat transfer coefficient is needed to handle some simplification on this topic. Finally, a linearization of this equation leads to an analogous mechanical model that can be assembled from two common spring- and one dashpot elements in a specific arrangement. This transfer into "mechanical language" enables a system description with a simple force-displacement law and a consideration of the nonobvious hysteresis and stiffness increase of an air spring from a mechanical point of view.

  1. Magnetization and Hysteresis of Dilute Magnetic-Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Skomski, Ralph; Balamurugan, B.; Sellmyer, D. J.

    2014-03-01

    Real-structure imperfections in dilute magnetic oxides tend to create small concentrations of local magnetic moments that are coupled by fairly long-range exchange interactions, mediated by p-electrons. The robustness of these interactions is caused by the strong overlap of the p orbitals, as contrasted to the much weaker interatomic exchange involving iron-series 3d electrons. The net exchange between defect moments can be positive or negative, which gives rise to spin structures with very small net moments. Similarly, the moments exhibit magnetocrystalline anisotropy, reinforced by electron hopping to and from 3d states and generally undergoing some random-anuisotropy averaging. Since the coercivity scales as 2K1/M and M is small, this creates pronounced and -- in thin films -- strongly anisotropic hysteresis loops. In finite systems with N moments, both K1 and M are reduced by a factor of order N1/2 due to random anisotropy and moment compensation, respectively, so that that typical coercivities are comparable to bulk magnets. Thermal activation readily randomizes the net moment of small oxide particles, so that the moment is easier to measure in compacted or aggregated particle ensembles. This research is supported by DOE (BES).

  2. On growth rate hysteresis and catastrophic crystal growth

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  3. Avalanches and hysteresis in frustrated superconductors and XY spin glasses.

    PubMed

    Sharma, Auditya; Andreanov, Alexei; Müller, Markus

    2014-10-01

    We study avalanches along the hysteresis loop of long-range interacting spin glasses with continuous XY symmetry, which serves as a toy model of granular superconductors with long-range and frustrated Josephson couplings. We identify sudden jumps in the T=0 configurations of the XY phases as an external field is increased. They are initiated by the softest mode of the inverse susceptibility matrix becoming unstable, which induces an avalanche of phase updates (or spin alignments). We analyze the statistics of these events and study the correlation between the nonlinear avalanches and the soft mode that initiates them. We find that the avalanches follow the directions of a small fraction of the softest modes of the inverse susceptibility matrix, similarly as was found in avalanches in jammed systems. In contrast to the similar Ising spin glass (Sherrington-Kirkpatrick) studied previously, we find that avalanches are not distributed with a scale-free power law but rather have a typical size which scales with the system size. We also observe that the Hessians of the spin-glass minima are not part of standard random matrix ensembles as the lowest eigenvector has a fractal support. PMID:25375434

  4. Extinction curves expected in young galaxies

    E-print Network

    Hiroyuki Hirashita; Takaya Nozawa; Takashi Kozasa; Takako T. Ishii; Tsutomu T. Takeuchi

    2005-01-10

    We investigate the extinction curves of young galaxies in which dust is supplied from Type II supernovae (SNe II) and/or pair instability supernovae (PISNe). We adopt Nozawa et al. (2003) for compositions and size distribution of grains formed in SNe II and PISNe. We find that the extinction curve is quite sensitive to internal metal mixing in supernovae (SNe). The extinction curves predicted from the mixed SNe are dominated by SiO2 and is characterised by steep rise from infrared to ultraviolet (UV). The dust from unmixed SNe shows shallower extinction curve, because of the contribution from large-sized (~ 0.1 um) Si grains. However, the progenitor mass is important in unmixed SNe II: If the progenitor mass is smaller than ~ 20 Msun, the extinction curve is flat in UV; otherwise, the extinction curve rises toward the short wavelength. The extinction curve observed in a high-redshift quasar (z=6.2) favours the dust production by unmixed SNe II. We also provide some useful observational quantities, so that our model might be compared with future high-z extinction curves.

  5. Hysteresis phenomenon of the field emission from carbon nanotube/polymer nanocomposite

    NASA Astrophysics Data System (ADS)

    Filippov, S. V.; Popov, E. O.; Kolosko, A. G.; Romanov, P. A.

    2015-11-01

    Using the high voltage scanning method and the technique of multichannel recording and processing of field emission (FE) characteristics in real time mode we found out some subtle effects on current voltage characteristics (IVC) of the multi-tip field emitters. We observed the direct and reverse hysteresis simultaneously in the same field emission experiment. Dependence of the form of IVC hysteresis on time of high voltage scanning was observed.

  6. 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)

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

    2013-05-01

    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.

  7. Living in Curved Momentum Space

    E-print Network

    J. Kowalski-Glikman

    2013-09-10

    In this paper we review some aspects of relativistic particles' mechanics in the case of a non-trivial geometry of momentum space. We start with showing how the curved momentum space arises in the theory of gravity in 2+1 dimensions coupled to particles, when (topological) degrees of freedom of gravity are solved for. We argue that there might exist a similar topological phase of quantum gravity in 3+1 dimensions. Then we characterize the main properties of the theory of interacting particles with curved momentum space and the symmetries of the action. We discuss the spacetime picture and the emergence of the principle of relative locality, according to which locality of events is not absolute but becomes observer dependent, in the controllable, relativistic way. We conclude with the detailed review of the most studied kappa-Poincare framework, which corresponds to the de Sitter momentum space.

  8. Quantum walks in curved spacetime

    E-print Network

    Pablo Arrighi; Stefano Facchini; Marcelo Forets

    2015-05-26

    A discrete-time Quantum Walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g. the Dirac equation), and thus provide us with discrete toy models of familiar particles (e.g. the electron). In this paper, we study the continuum limit of a wide class of QWs, and show that it leads to all those PDEs corresponding to the Hamiltonian form of the massive curved Dirac equation in (1 + 1) dimensions. Therefore a certain QW, which we make explicit, provides us with a unitary discrete toy model of the electron as a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.

  9. Hysteresis Effects and Strain-Induced Homogeneity Effects in Base Metal Thermocouples

    NASA Astrophysics Data System (ADS)

    Pavlasek, P.; Elliott, C. J.; Pearce, J. V.; Duris, S.; Palencar, R.; Koval, M.; Machin, G.

    2015-03-01

    Thermocouples are used in a wide variety of industrial applications in which they play an important role for temperature control and monitoring. Wire inhomogeneity and hysteresis effects are major sources of uncertainty in thermocouple measurements. To efficiently mitigate these effects, it is first necessary to explore the impact of strain-induced inhomogeneities and hysteresis, and their contribution to the uncertainty. This article investigates homogeneity and hysteresis effects in Types N and K mineral-insulated metal-sheathed (MIMS) thermocouples. Homogeneity of thermocouple wires is known to change when mechanical strain is experienced by the thermoelements. To test this influence, bends of increasingly small radii, typical in industrial applications, were made to a number of thermocouples with different sheath diameters. The change in homogeneity was determined through controlled immersion of the thermocouple into an isothermal liquid oil bath at and was found to be very small at for Type K thermocouples, with no measureable change in Type N thermocouples found. An experiment to determine the hysteresis effect in thermocouples was performed on swaged, MIMS Type N and Type K thermocouples, in the temperature range from to . The hysteresis measurements presented simulate the conditions that thermocouples may be exposed to in industrial applications through continuous cycling over 136 h. During this exposure, a characteristic drift from the reference function has been observed but no considerable difference between the heating and cooling measurements was measureable. The measured differences were within the measurement uncertainties; therefore, no hysteresis was observed.

  10. Electrowetting on dielectrics on lubricating fluid based slippery surfaces with negligible hysteresis

    E-print Network

    Jitesh Barman; Arun Kumar Nagarajan; Krishnacharya Khare

    2015-07-09

    Low voltage electrowetting on dielectrics on substrates with thin layer of lubricating fluid to reduce contact angle hysteresis is reported here. On smooth and homogeneous solid surfaces, it is extremely difficult to reduce contact angle hysteresis (contact angle difference between advancing and receding drop volume cycle) and the electrowetting hysteresis (contact angle difference between advancing and receding voltage cycle) below 10{\\deg}. On the other hand, electrowetting hysteresis on rough surfaces can be relatively large (>30{\\deg}) therefore they are of no use for most of the fluidic devices. In the present report we demonstrate that using a thin layer of dielectric lubricating fluid on top of the solid dielectric surface results in drastic reduction in contact angle hysteresis as well as electrowetting hysteresis (electrowetting equation to the experimental electrowetting data reveal that the dielectric lubricating fluid layer is only responsible for smooth movement of the three phase contact line of the liquid drop and does not affect the effective specific capacitance of the system.

  11. Effect of hysteresis on the stability of an embankment under transient seepage

    NASA Astrophysics Data System (ADS)

    Liu, K.; Vardon, P. J.; Arnold, P.; Hicks, M. A.

    2015-09-01

    Hysteresis is a well-known phenomenon that exists in the soil water retention behaviour of unsaturated soils. However, there is little research on the effects of hysteresis on slope stability. If included in slope stability analyses, commonly the suction in the unsaturated zone is taken as non-hysteretic. In this paper, the authors investigate the effect of hysteresis on the stability of an embankment under transient seepage. A scenario of water level fluctuation has been assessed, in which a cyclic external water level fluctuates between a low and high level. It was found that the factor of safety (FOS), the volumetric water content and the suction in the unsaturated zone are significantly affected by hysteresis. It was also found that, when the period of water level fluctuation in one cycle is relatively small, there is little difference in the FOS between the hysteretic case and non-hysteretic case. However, when the period exceeds a certain threshold value, significant differences between these two cases can be observed. Compared to the case in which hysteresis is considered, the FOS is higher in the case which does not consider hysteresis. This suggests that the non-hysteretic case may overestimate slope stability, leading to a potentially dangerous situation. Moreover, the period under which there emerge large differences between the hysteretic and non-hysteretic case is strongly related to the magnitude of hydraulic conductivity and the period of the cyclic water level fluctuation.

  12. Three-stage evolution of dynamic hysteresis scaling behavior in 63PbTiO{sub 3}-37BiScO{sub 3} bulk ceramics

    SciTech Connect

    Yu Gang; Dong Xianlin; Wang Genshui; Cao Fei; Chen Xuefeng; Nie Hengchang

    2010-05-15

    The ferroelectric hysteresis loops of 63PbTiO{sub 3}-37BiScO{sub 3} ceramics were measured under sinusoidal electric fields in the range of frequency from 0.1 to 100 Hz and field from 5 to 55 kV/cm. The fitting results showed two linear relations existed between the logarithm of hysteresis area and the logarithm of the amplitude of field E{sub 0} in the first and third field region. In the second region, no linear relation existed due to polarization reversal. These three-stage behaviors were distinct from the existing two-stage behaviors. The slopes in the third stage increase with the increasing of frequency, which can be attributed to dielectric loss under high frequency.

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

    SciTech Connect

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

    2012-03-01

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

  14. Noise-affected I-V curves in small hysteretic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Kautz, R. L.; Martinis, John M.

    1990-12-01

    We investigate the noise-affected I-V curves of small-area Josephson junctions through experiment, simulation, and theory. In particular, we consider I-V curves in which two different states of finite voltage coexist at the same dc bias: a high-voltage state that corresponds to the usual quasiparticle branch and a low-voltage state that is characterized by thermally activated phase diffusion. The observed hysteresis between the phase-diffusion and quasiparticle branches cannot be explained within the context of the simple resistively and capacitively shunted junction (RCSJ) model but is explained by extended models in which the damping increases with frequency. Frequency-dependent damping is shown to produce a qualitative change in the attractors of the noise-free system which allows the two voltage states to be simultaneously stable. This picture is confirmed by Monte Carlo simulations which accurately reproduce the experimental I-V curves of two different samples over a wide range of temperatures. In addition we develop analytic expressions for three key parameters of the I-V curve of junctions displaying hysteresis between the phase-diffusion and quasiparticle branches: the initial slope of the phase-diffusion branch, the bias level at which the junction switches from the phase-diffusion branch to the quasiparticle branch, and the bias level at which it returns to the phase-diffusion branch.

  15. Breaking an Epigenetic Chromatin Switch: Curious Features of Hysteresis in Saccharomyces cerevisiae Telomeric Silencing

    PubMed Central

    Nagaraj, Vijayalakshmi H.; Mukhopadhyay, Swagatam; Dayarian, Adel; Sengupta, Anirvan M.

    2014-01-01

    In addition to gene network switches, local epigenetic modifications to DNA and histones play an important role in all-or-none cellular decision-making. Here, we study the dynamical design of a well-characterized epigenetic chromatin switch: the yeast SIR system, in order to understand the origin of the stability of epigenetic states. We study hysteresis in this system by perturbing it with a histone deacetylase inhibitor. We find that SIR silencing has many characteristics of a non-linear bistable system, as observed in conventional genetic switches, which are based on activities of a few promoters affecting each other through the abundance of their gene products. Quite remarkably, our experiments in yeast telomeric silencing show a very distinctive pattern when it comes to the transition from bistability to monostability. In particular, the loss of the stable silenced state, upon increasing the inhibitor concentration, does not seem to show the expected saddle node behavior, instead looking like a supercritical pitchfork bifurcation. In other words, the ‘off’ state merges with the ‘on’ state at a threshold concentration leading to a single state, as opposed to the two states remaining distinct up to the threshold and exhibiting a discontinuous jump from the ‘off’ to the ‘on’ state. We argue that this is an inevitable consequence of silenced and active regions coexisting with dynamic domain boundaries. The experimental observations in our study therefore have broad implications for the understanding of chromatin silencing in yeast and beyond. PMID:25536038

  16. Dielectric Hysteresis, Relaxation Dynamics, and Non-volatile Memory Effect in Carbon Nanotube Dispersed Liquid Crystal

    E-print Network

    Rajratan Basu; Germano S. Iannacchione

    2009-08-07

    The self-organizing properties of nematic liquid crystals (LC) can be used to template carbon nanotubes (CNTs) on a macroscopic dimension. The nematic director field, coupled to the dispersed CNT long-axis, enables controlled director reorientation using well-established methods of LC alignment techniques, such as patterned-electrode-surface, electric fields, and magnetic fields. Electric field induced director rotation of a nematic LC+CNT system is of potential interests due to its possible applications as a nano electromechanical system. The relaxation mechanism for a LC+CNT composite, on the removal of the applied field, reveals the intrinsic dynamics of this anisotropic system. Dielectric hysteresis and temperature dependence of the dielectric constant coherently shows the ferroelectric-type behavior of the LC+CNT system in the nematic phase. The strong surface anchoring of LC molecules on CNT walls results in forming local isolated pseudo-nematic domains in the isotropic phase. These domains, being anisotropic, respond to external fields, but, do not relax back to the original state on switching of the field off, showing non-volatile memory effect.

  17. Equilibria of point charges on convex curves

    NASA Astrophysics Data System (ADS)

    Khimshiashvili, G.; Panina, G.; Siersma, D.

    2015-12-01

    We study the equilibrium positions of three points on a convex curve under influence of the Coulomb potential. We identify these positions as orthotripods, three points on the curve having concurrent normals. This relates the equilibrium positions to the caustic (evolute) of the curve. The concurrent normals can only meet in the core of the caustic, which is contained in the interior of the caustic. Moreover, we give a geometric condition for three points in equilibrium with positive charges only. For the ellipse we show that the space of orthotripods is homeomorphic to a 2-dimensional bounded cylinder.

  18. Replication and Analysis of Ebbinghaus’ Forgetting Curve

    PubMed Central

    Murre, Jaap M. J.; Dros, Joeri

    2015-01-01

    We present a successful replication of Ebbinghaus’ classic forgetting curve from 1880 based on the method of savings. One subject spent 70 hours learning lists and relearning them after 20 min, 1 hour, 9 hours, 1 day, 2 days, or 31 days. The results are similar to Ebbinghaus' original data. We analyze the effects of serial position on forgetting and investigate what mathematical equations present a good fit to the Ebbinghaus forgetting curve and its replications. We conclude that the Ebbinghaus forgetting curve has indeed been replicated and that it is not completely smooth but most probably shows a jump upwards starting at the 24 hour data point. PMID:26148023

  19. Cosmic string lensing and closed timelike curves

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    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.

  20. Random Walk and Broad Distributions on Fractal Curves

    E-print Network

    Seema Satin; A. D. Gangal

    2011-03-27

    In this paper we analyse random walk on a fractal structure, specifi- cally fractal curves, using the recently develped calculus for fractal curves. We consider only unbiased random walk on the fractal stucture and find out the corresponding probability distribution which is gaussian like in nature, but shows deviation from the standard behaviour. Moments are calculated in terms of Euclidean distance for a von Koch curve. We also analyse Levy distribution on the same fractal structure, where the dimen- sion of the fractal curve shows significant contribution to the distrubution law by modyfying the nature of moments. The appendix gives a short note on Fourier transform on fractal curves.