Sample records for hysteresis curve shows

  1. A physical model for hysteresis curves of ferroelectric ceramics

    Microsoft Academic Search

    G. Arlt

    1996-01-01

    A general model for the simulation and for the interpretation of hysteresis curves is presented. The model opens the possibility to calculate hysteresis curves if the electrostatic interaction of grains in a critical volume can be treated quantitatively. The hysteresis curve is described by a progress parameter ?. The effective polarization Peff(?) in the process of inversion is approximated by

  2. Rotational hysteresis of torque curves in polycrystalline ferro/antiferromagnetic systems

    SciTech Connect

    Zhang, K.; Kai, T.; Zhao, T.; Fujiwara, H.; Hou, C.; Kief, M. T.

    2001-06-01

    Rotational hysteresis of ferromagnetic (F)/antiferromagnetic (AF) exchange coupled systems was studied by using NiFe/IrMn, NiFe/FeMn, and NiFe/NiMn samples sputter deposited under almost the same conditions, although the sample of NiFe/NiMn was annealed later to obtain the antiferromagnetic phase for the NiMn layer. The rotational hysteresis of each sample exhibited quite a different feature from each other, especially in the rotational hysteresis{endash}magnetization angle curves. The NiFe/IrMn bilayer showed a dip at around the antiparallel direction to the applied field direction during sample preparation (pinning direction), while the NiFe/NiMn bilayer exhibited a large peak in that direction. The NiFe/FeMn bilayer did not show any noticeable structure in the rotational hysteresis{endash}magnetization curve. Based on the analysis of those data done by using the model recently proposed by the authors, the following was inferred: (1) The distribution of the anisotropy easy axes of IrMn of the NiFe/IrMn bilayer grains is limited in some range of angles around the pinning direction. Some direct exchange coupling exists between the IrMn grains. (2) The distribution of the anisotropy easy axes of FeMn grains of the NiFe/FeMn bilayer is almost random and the direct exchange coupling between the FeMn grains is negligible. (3) In the NiFe/NiMn bilayer, substantial strength of direct exchange coupling exists between some of the grains which switch and the ones which do not switch with the rotation of the magnetization of the NiFe layer, although the volume fraction of the former is much smaller than the latter. {copyright} 2001 American Institute of Physics.

  3. Rotational hysteresis of torque curves in polycrystalline ferro/antiferromagnetic systems

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Kai, T.; Zhao, T.; Fujiwara, H.; Hou, C.; Kief, M. T.

    2001-06-01

    Rotational hysteresis of ferromagnetic (F)/antiferromagnetic (AF) exchange coupled systems was studied by using NiFe/IrMn, NiFe/FeMn, and NiFe/NiMn samples sputter deposited under almost the same conditions, although the sample of NiFe/NiMn was annealed later to obtain the antiferromagnetic phase for the NiMn layer. The rotational hysteresis of each sample exhibited quite a different feature from each other, especially in the rotational hysteresis-magnetization angle curves. The NiFe/IrMn bilayer showed a dip at around the antiparallel direction to the applied field direction during sample preparation (pinning direction), while the NiFe/NiMn bilayer exhibited a large peak in that direction. The NiFe/FeMn bilayer did not show any noticeable structure in the rotational hysteresis-magnetization curve. Based on the analysis of those data done by using the model recently proposed by the authors, the following was inferred: (1) The distribution of the anisotropy easy axes of IrMn of the NiFe/IrMn bilayer grains is limited in some range of angles around the pinning direction. Some direct exchange coupling exists between the IrMn grains. (2) The distribution of the anisotropy easy axes of FeMn grains of the NiFe/FeMn bilayer is almost random and the direct exchange coupling between the FeMn grains is negligible. (3) In the NiFe/NiMn bilayer, substantial strength of direct exchange coupling exists between some of the grains which switch and the ones which do not switch with the rotation of the magnetization of the NiFe layer, although the volume fraction of the former is much smaller than the latter.

  4. An automatic system for determining the effects of temperature on the hysteresis curves of ion-selective electrodes

    PubMed Central

    Magalhães, Júlia M. C. S.

    1997-01-01

    This paper describes an automatic system which measures the effect of temperature variations on the response of ion-selective electrodes (hysteresis curves). The system is managed by a computer program which plots hysteresis curves following a pre-established temperature cycle, from setting and controlling the temperature of the water-bath, to acquiring the response potentials of up to five electrodes after temperature stabilization. PMID:18924793

  5. 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.

  6. 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

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

    NASA Astrophysics Data System (ADS)

    Stan, Raluca-Maria; Gaina, Roxana; Enachescu, Cristian; Tanasa, Radu; Stancu, Alexandru; Bronisz, Robert

    2015-05-01

    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 [Fe1-xZnx(bbtr)3](ClO4)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.

  8. Quantum Hydrodynamic Simulation of Hysteresis in the Resonant Tunneling Diode

    Microsoft Academic Search

    Zhangxin Chen; Bernardo Cockburn; Carl L. Gardner; Joseph W. Jerome

    1995-01-01

    Hysteresis in the current-voltage curve of a resonant tunneling diode is simulated and analyzed in the quantum hydrodynamic (QHD) model for semiconductor devices. The simulations are the first to show hysteresis in the QHD equations and to confirm that bistability is an intrinsic property of the resonant tunneling diode. Hysteresis appears in many settings in fluid dynamics. The simulations presented

  9. Rotational hysteresis of torque curves in polycrystalline ferro\\/antiferromagnetic systems

    Microsoft Academic Search

    K. Zhang; T. Kai; T. Zhao; H. Fujiwara; C. Hou; M. T. Kief

    2001-01-01

    Rotational hysteresis of ferromagnetic (F)\\/antiferromagnetic (AF) exchange coupled systems was studied by using NiFe\\/IrMn, NiFe\\/FeMn, and NiFe\\/NiMn samples sputter deposited under almost the same conditions, although the sample of NiFe\\/NiMn was annealed later to obtain the antiferromagnetic phase for the NiMn layer. The rotational hysteresis of each sample exhibited quite a different feature from each other, especially in the rotational

  10. Curves showing column strength of steel and duralumin tubing

    NASA Technical Reports Server (NTRS)

    Ross, Orrin E

    1929-01-01

    Given here are a set of column strength curves that are intended to simplify the method of determining the size of struts in an airplane structure when the load in the member is known. The curves will also simplify the checking of the strength of a strut if the size and length are known. With these curves, no computations are necessary, as in the case of the old-fashioned method of strut design. The process is so simple that draftsmen or others who are not entirely familiar with mechanics can check the strength of a strut without much danger of error.

  11. Hysteresis Simulation

    NSDL National Science Digital Library

    Paul Houle

    You can choose from three values for disorder of the system and select a goal for the external magnetic field by clicking in a "control bar" area. Output graphs show qualitative information, but no numbers. A brief explanation of the physics of hysteresis is provided and the java source code can be downloaded.

  12. Effect of applied tensile stress on the hysteresis curve and magnetic domain structure of grain-oriented transverse Fe-3%Si steel

    NASA Astrophysics Data System (ADS)

    Perevertov, O.; Thielsch, J.; Schäfer, R.

    2015-07-01

    The effect of an elastic applied tensile stress on the quasistatic hysteresis curve and domain structure in conventional (110) [001] Fe-3%Si steel, cut transversely to the rolling direction, is studied. The magnetic domains and magnetization processes were observed by longitudinal Kerr microscopy at different levels of stress. It is shown that above 8 MPa the bulk hysteresis loop can be described with a good accuracy by the action of an effective field, which is the product of the stress and a function of magnetization. Domain observation reveals that the reasons for the effective field are demagnetizing fields due to the disappearance of supplementary domains at low applied field and the formation of different domain systems in different grains at low and moderate fields. The latter are caused by differences in grain sensitivity to stress depending on the degree of misorientation and grain boundary orientation. A decrease of the effective field above 1 T is connected with a transformation of all grains into the same domain system - the column pattern. The hysteresis loop behavior is qualitatively the same as for strips cut in rolling direction and for non-oriented strips.

  13. 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

  14. 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

  15. 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...

  16. Plant thermal hysteresis proteins.

    PubMed

    Urrutia, M E; Duman, J G; Knight, C A

    1992-05-22

    Proteins which produce a thermal hysteresis (i.e. lower the freezing point of water below the melting point) are common antifreezes in cold adapted poikilothermic animals, especially fishes from ice-laden seas and terrestrial arthropods. However, these proteins have not been previously identified in plants. 16 species of plants collected from northern Indiana in autumn and winter had low levels of thermal hysteresis activity, but activity was absent in summer. This suggests that thermal hysteresis proteins may be a fairly common winter adaptation in angiosperms. Winter stem fluid from the bittersweet nightshade, Solanum dulcamara L., also showed the recrystallization inhibition activity characteristic of the animal thermal hysteresis proteins (THPs), suggesting a possible function for the THPs in this freeze tolerant species. Other potential functions are discussed. Antibodies to an insect THP cross reacted on immunoelectroblots with proteins in S. dulcamara stem fluid, indicating common epitopes in the insect and plant THPs. PMID:1599942

  17. Mathematical models of hysteresis

    SciTech Connect

    NONE

    1998-08-01

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

  18. Quantum Hydrodynamic Simulation of Hysteresis in the Resonant Tunneling Diode

    E-print Network

    Jerome, Joseph W.

    Quantum Hydrodynamic Simulation of Hysteresis in the Resonant Tunneling Diode Zhangxin Chen \\Lambda Hysteresis in the current­voltage curve of a resonant tunneling diode is simulated and analyzed is an intrinsic property of the resonant tunneling diode. Hysteresis appears in many settings in fluid dynamics

  19. 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.

  20. Pulsed I -V measurement method to obtain hysteresis-free characteristics of graphene FETs

    NASA Astrophysics Data System (ADS)

    Park, Jun-Mo; Lee, Dongho; Shim, Jeoyoung; Jeon, Taehan; Eom, Kunsun; Park, Byung-Gook; Lee, Jong-Ho

    2014-09-01

    Current-voltage (I-V) characteristics of the graphene field effect transistors (GFETs) are measured by the dc, fast I-V (FIV), and pulsed I-V (PIV) methods and analyzed. The hysteresis and conductance in the dc measurement are affected by the sweeping bias range and direction. The I-V curves measured by the FIV method show reduced hysteresis and enhanced conductance at a faster sweeping rate, but are still affected by the sweeping bias range. By applying the PIV method, the hysteresis can be suppressed significantly while the conductance is improved by controlling turn-on, turn-off times (t on and t off) and the gate bias during t off (V base) regardless of the sweeping bias range. With short t on, long t off, and V base of 0 V, the hysteresis-free characteristics of GFETs are obtained.

  1. 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.

  2. Scalar and vector hysteresis simulations using HysterSoft

    NASA Astrophysics Data System (ADS)

    Dimian, M.; Andrei, P.

    2015-02-01

    Hysteresis modeling has become an important research area with many applications in science and engineering. In this article we present a unified and robust simulation framework designed to perform scalar and vector hysteresis modeling. The framework is based on HysterSoft© which is a simulation platform that can be interfaced with other libraries and simulation programs to model various aspects of hysteresis. We describe the main features of our simulation framework by focusing on scalar and vector hysteresis modeling, direct and inverse modeling, dynamic hysteresis modeling, first-order reversal-curves analysis, identification of the scalar and vector Preisach distribution function using an experimental first- order reversal-curves, noise passage analysis through hysteretic systems, and thermal relaxation in scalar and vector hysteresis. The simulation modules, the user-defined features, and various parameter identification techniques are also presented.

  3. NONLINEAR SEMIGROUP METHODS IN PROBLEMS WITH HYSTERESIS

    Microsoft Academic Search

    Jana Kopfov

    Results from a nonlinear semigroup theory are applied to get ex- istence and uniqueness for PDEs with hysteresis. The hysteresis nonlinearity considered is of the generalized play operator type, but can be easily extended to a generalized Prandtl-Ishlinskii operator of play type, both possibly discon- tinuous. 1. Introduction. We show in this paper how nonlinear semigroup theory can be used

  4. 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.

  5. Tracking control of a piezoceramic actuator with hysteresis compensation using inverse Preisach model

    Microsoft Academic Search

    G. Song; Jinqiang Zhao; Xiaoqin Zhou; J. Alexis De Abreu-García

    2005-01-01

    This paper presents the classical Preisach hysteresis modeling and tracking control of a curved pre-stressed piezoceramic patch actuator system with severe hysteresis. The actuator is also flexible with very small inherent damping. It has potential applications in active antennas. A series of tests are conducted to study the hysteresis properties of the piezoceramic actuator system. The numerical expressions of the

  6. Relative Permeability Hysteresis: Laboratory Measurements and a Conceptual Model

    Microsoft Academic Search

    E. M. Braun; R. F. Holland

    1995-01-01

    Relative permeability hysteresis has been measured for a water-wet outcrop rock sample and a mixed-wet reservoir core. For the oil phase, imbibition and drainage relative permeability curves differed significantly. The difference was much less pronounced for the water phase. Scanning curves, which characterize transitions between imbibition and drainage curves, were also measured. A notable characteristic of the oil relative permeability

  7. 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)

  8. 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.

  9. Hysteresis effects in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Sacchetti, Andrea

    2010-07-01

    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.

  10. 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...

  11. 51A Simple Model for Atmospheric Carbon Dioxide The graph to the left shows the 'Keeling Curve' which plots the increase in

    E-print Network

    51A Simple Model for Atmospheric Carbon Dioxide The graph to the left shows the 'Keeling Curve' which plots the increase in atmospheric carbon dioxide between 1958-2005. The average net annual rate of the element carbon on Earth. Note that, for every 44 gigatons of the carbon dioxide molecule, there are 12

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

    Microsoft Academic Search

    N. Schmidt; H. Guldner

    1996-01-01

    An approach to plotting hysteresis curves of soft magnetic materials using a personal computer assisted measuring system is presented. The resulting hysteresis curves provide enough detail to allow determination of the parameters required for a simulation with PSPICE (Jiles-Atherton model) or the Hodgdon\\/Carpenter model. The magnetic core loss for different materials and core shapes can be determined at frequencies up

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

    SciTech Connect

    Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, A [BABES-BOLYAI UNIV.

    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.

  14. The extrinsic hysteresis behavior of dilute binary ferrofluids.

    PubMed

    Lin, Lihua; Li, Jian; Lin, Yueqiang; Liu, Xiaodong; Chen, Longlong; Li, Junming; Li, Decai

    2014-10-01

    We report on the magnetization behavior of dilute binary ferrofluids based on ?-Fe(2)O(3)/Ni(2)O(3) composite nanoparticles (A particles), with diameter about 11 nm, and ferrihydrite (Fe(5)O(7)(OH) ?4H2O) nanoparticles (B particles), with diameter about 6 nm. The results show that for the binary ferrofluids with A-particle volume fraction ?(A) = 0.2% and B-particle volume fractions ?(B) = 0.1% and ?(B) = 0.6%, the magnetization curves exhibit quasi-magnetic hysteresis behavior. The demagnetizing curves coincide with the magnetizing curves at high fields. However, for single ?-Fe(2)O(3)/Ni(2)O(3) ferrofluids with ?(A) = 0.2% and binary ferrofluids with ?(A) = 0.2% and ?(B) = 1.0%, the magnetization curves do not behave in this way. Additionally, at high field (750 kA/m), the binary ferrofluid with ?(B) = 1.0% has the smallest magnetization. From the model-of-chain theory, the extrinsic hysteresis behavior of these samples is attributed to the field-induced effects of pre-existing A particle chains, which involve both Brownian rotation of the chains'moments and a Néel rotation of the particles' moments in the chains. The loss of magnetization for the ferrofluids with ?(B) = 1.0% is attributed to pre-existing ring-like A-particle aggregates. These magnetization behaviors of the dilute binary ferrofluids not only depend on features of the strongly magnetic A-particle system, but also modifications of the weaker magnetic B-particle system. PMID:25365919

  15. Magnetic hysteresis behavior and magnetic pinning in a d0 ferromagnet/superconductor nanostructure

    NASA Astrophysics Data System (ADS)

    Uchino, Takashi; Uenaka, Yuki; Soma, Haruka; Sakurai, Takahiro; Ohta, Hitoshi

    2014-02-01

    We investigate the interaction between superconductivity and defect-induced d0 ferromagnetism using a composite consisting of MgB2 and MgO nanocrystals. The composite exhibits a ferromagnetic hysteresis behavior in the temperature region from 40 to 300 K. Defective MgO nanocrystals (˜20 nm) embedded in the composite are considered to be responsible for the observed ferromagnetism. The zero field cool and field cool magnetization curves show that the superconducting transition occurs at Tc = 38.6 K, in agreement with Tc of pure MgB2. In the temperature region from Tc to 0.9Tc (˜35 K), the magnetization hysteresis curves show a superposition of ferromagnetic (F) and superconducting (S) signals. When the temperature of the system is decreased below 0.65Tc (˜25 K), the S signals dominate over the F signals. The resulting magnetic hysteresis loops are highly asymmetric and the descending filed branch is nearly flat, as predicted in the case of surface pinning. At temperatures below 0.5Tc (˜20 K), a sharp peak is developed near zero field in the magnetization hysteresis curves, implying an enhancement of superconducting vortex pinning. The observed pinning enhancement most likely results from magnetic pinning due to randomly distributed magnetic MgO grains, which yield the magnetic inhomogeneity and the related pinning potential in a length scale of ˜100 nm. Thus, the present ferromagnetic/superconducting composite provides an ideal model system that demonstrates the availability of d0 ferromagnetism as a source of magnetic potential for effective vortex pinning.

  16. Hysteresis in soft magnetic materials

    Microsoft Academic Search

    Vittorio Basso; Giorgio Bertotti

    2000-01-01

    The physical origin of hysteresis in soft magnetic materials is discussed and the various theoretical approaches proposed for its interpretation are reviewed. Particular attention is paid to the study of fundamental aspects of hysteresis through Barkhausen effect and thermal relaxation experiments, to the connection between hysteresis, macroscopic magnetic properties and microstructural features and finally to the development of mathematical formulations

  17. Hysteresis of ionization waves

    NASA Astrophysics Data System (ADS)

    Dinklage, A.; Bruhn, B.; Testrich, H.; Wilke, C.

    2008-06-01

    A quasi-logistic, nonlinear model for ionization wave modes is introduced. Modes are due to finite size of the discharge and current feedback. The model consists of competing coupled modes and it incorporates spatial wave amplitude saturation. The hysteresis of wave mode transitions under current variation is reproduced. Sidebands are predicted by the model and found in experimental data. The ad hoc model is equivalent to a general—so-called universal—approach from bifurcation theory.

  18. 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.

  19. Continuum damage mechanics for hysteresis and fatigue of quasi-brittle materials and structures

    Microsoft Academic Search

    R. Desmorat; F. Ragueneau; H. Pham

    2007-01-01

    For a material exhibiting hysteresis such as quasi-brittle materials, it is natural to consider that hysteresis and fatigue are related to each other. One shows in the present work that damage, from the continuum damage mechanics point of view, may be seen as the link between both phenomena. One attempts, hence, to set up a unified modelling of hysteresis and

  20. 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.

  1. Modelling of hysteresis in thin superconducting screens for mixed-mu suspension systems

    SciTech Connect

    Asher, G.M.; Williams, J.T.; Walters, C.R.; Joyce, H.; Paul, R.J.A.

    1982-03-01

    Mixed-mu levitation is the principle whereby iron is levitated in a magnetic field and stabilized by the proximity of diamagnetic superconducting screens. In a dynamic environment, the screens are subject to changing magnetic fields thus causing hysteresis losses in the superconducting material. This paper is concerned with the modeling of such hysteresis. A finite difference approximation to the current and field distributions is employed, the current distribution being made consistent with critical current values by iteration. Square and disc shaped screen samples are studied and hysteresis curves computed. It is shown that the method represents a fair approximation to the hysteresis behavior of thin superconducting screens. 8 refs.

  2. 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.

  3. 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.

  4. 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.

  5. Purification and characterization of a thermal hysteresis protein from a plant, the bittersweet nightshade Solanum dulcamara.

    PubMed

    Duman, J G

    1994-05-18

    Thermal hysteresis proteins (THPs), which depress the freezing point of water below the melting point (producing a characteristic thermal hysteresis), are well known for their antifreeze activity in both fish and terrestrial arthropods, but have only recently been identified in plants. This study describes the purification of a THP from winter-collected bittersweet nightshade, Solanum dulcamara, using ion exchange and preparative 'free flow' isoelectric focusing. The THP has a molecular mass of 67 kDa (considerably larger than those of animal THPs), and an unusually high glycine component (23.7 mol%). Treatments of the THP with periodate or borate caused inactivation, suggesting the presence of carbohydrate. More specific treatments directed at galactose (beta-galactosidase or Abrus precatorius lectin) also resulted in inactivation, indicating that galactose is present. A thermal hysteresis activity versus THP concentration curve showed that the specific activity of the S. dulcamara THP is lower than that of any known animal THP. The functional significance of this low activity is discussed. PMID:8186242

  6. Quantum curves

    E-print Network

    Albert Schwarz

    2014-08-16

    One says that a pair (P,Q) of ordinary differential operators specify a quantum curve if [P,Q]=const. If a pair of difference operators (K,L) obey the relation KL=const LK 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 show how to quantize a pair of commuting differential or difference operators (i.e. to construct the corresponding quantum curve or discrete quantum curve). The KP-hierarchy acts on the moduli space of quantum curves; we prove that similarly the discrete KP-hierarchy acts on the moduli space of discrete quantum curves.

  7. Applications of a theory of ferromagnetic hysteresis

    SciTech Connect

    Hodgdon, M.L.

    1987-01-01

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

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

    SciTech Connect

    Lee, J.H.; Hyun, D.S. (Hanyang Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering)

    1999-05-01

    In high speed applications of PMASynRM, hysteresis losses can become the major cause of power dissipation. Therefore, whereas in other kind of machines a rough estimation of hysteresis can be accepted, their importance in PMASynRM justifies a greater effort in calculating them more precisely. This study investigates the hysteresis phenomena of the Permanent Magnet Assisted Synchronous Reluctance Motor (PMASynRM) using coupled FEM and Preisach modelling. Preisach's model, which allows accurate prediction of hysteresis, is adopted in this procedure to provide a nonlinear solution. The computer simulation and experimental result for the i-[lambda] loci show the propriety of the proposed method.

  9. Hysteresis Losses in Rolling and Sliding Friction

    Microsoft Academic Search

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

    1961-01-01

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

  10. Hysteresis errors of commonly used sensor materials

    Microsoft Academic Search

    Bulent Aydemir; Levent Yagmur; Sinan Fank

    2010-01-01

    In this study, the hysteresis errors of 17-4 PH precipitation hardened stainless steel, aged Cu–Be (copper beryllium) alloy and AISI 4340 steel, which are commonly used as spring materials for sensors, were determined. Various heat treatment processes were applied to the samples of sensor materials in order to decrease the hysteresis error. The effect of the microstructure on the hysteresis

  11. 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 [Department of Materials Science, Sichuan University, Chengdu 610064 (China)

    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.

  12. 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

  13. Persistent hysteresis in graphene-mica van der Waals heterostructures

    NASA Astrophysics Data System (ADS)

    Mohrmann, Jens; Watanabe, Kenji; Taniguchi, Takashi; Danneau, Romain

    2015-01-01

    We report the study of electronic transport in graphene-mica van der Waals heterostructures. We have designed various graphene field-effect devices in which mica is utilized as a substrate and/or gate dielectric. When mica is used as a gate dielectric we observe a very strong positive gate voltage hysteresis of the resistance, which persists in samples that were prepared in a controlled atmosphere down to even millikelvin temperatures. In a double-gated mica-graphene-hBN van der Waals heterostructure, we found that while a strong hysteresis occurred when mica was used as a substrate/gate dielectric, the same graphene sheet on mica substrate no longer showed hysteresis when the charge carrier density was tuned through a second gate with the hBN dielectric. While this hysteretic behavior could be useful for memory devices, our findings confirm that the environment during sample preparation has to be controlled strictly.

  14. Persistent hysteresis in graphene-mica van der Waals heterostructures.

    PubMed

    Mohrmann, Jens; Watanabe, Kenji; Taniguchi, Takashi; Danneau, Romain

    2015-01-01

    We report the study of electronic transport in graphene-mica van der Waals heterostructures. We have designed various graphene field-effect devices in which mica is utilized as a substrate and/or gate dielectric. When mica is used as a gate dielectric we observe a very strong positive gate voltage hysteresis of the resistance, which persists in samples that were prepared in a controlled atmosphere down to even millikelvin temperatures. In a double-gated mica-graphene-hBN van der Waals heterostructure, we found that while a strong hysteresis occurred when mica was used as a substrate/gate dielectric, the same graphene sheet on mica substrate no longer showed hysteresis when the charge carrier density was tuned through a second gate with the hBN dielectric. While this hysteretic behavior could be useful for memory devices, our findings confirm that the environment during sample preparation has to be controlled strictly. PMID:25483818

  15. Observations of Hysteresis Among Indicators of Solar Activity

    NASA Astrophysics Data System (ADS)

    Bachmann, K. T.; Ranganath, A.

    1999-05-01

    We show that filtered time series of five indicators of solar activity exhibit significant solar-cycle-dependent differences in their relative variations. This study expands upon previous work by including data from recent NASA missions, indicating that the detected hysteresis patterns continue through the decline of solar cycle 22. Among the indicators that we study, we find that the hysteresis effects are approximately simple phase shifts that we present qualitatively via plots similar to Lissajous figures. These phase shifts correspond to time delays of less than three months behind the leading indicator, the International Sunspot Number, and are small compared to the typical eleven-year solar cycle. We believe that hysteresis represents a real delay in the onset and decline for changing solar emission at various wavelengths. Our research is funded by the Research Corporation and by the NASA Joint Venture (JOVE) program.

  16. The Effect Of Hysteresis And Heterogeneity On Specific Yield And Fillable Porosity: Theoretical Considerations

    NASA Astrophysics Data System (ADS)

    Patros, T.

    2011-12-01

    Specific yield, or drainable porosity, is an important component in estimating groundwater recharge (GWR) using the water table fluctuation (WTF) method. The use of soil fillable porosity instead of specific yield has been proposed due to the effect of hysteresis on the soil moisture characteristic curve (SMCC), which shows that the specific yield may be larger than the fillable porosity, resulting in larger estimation of GWR. Here, an attempt is made to compare the specific yield and the fillable porosity mathematically, using an equation(s) for the SMCC (including hysteresis) from the literature. The implication of using either the specific yield or the fillable porosity on GWR estimation in homogeneous and layered heterogeneous profiles for a variety of soil textural classes is presented. In addition, replacing soil residual volumetric water content with soil field capacity, or specific retention, as a lower limit of the SMCC, and the influence of that change on GWR estimation, is critically examined for both the specific yield and the fillable porosity.

  17. The hysteresis cycle of concentration in a solution droplet under changing humidity

    NASA Astrophysics Data System (ADS)

    Malvestuto, Vincenzo; Ascoli, Sergio; Sabina Lanotte, Alessandra

    2014-07-01

    For a solution droplet in equilibrium with the atmospheric environment, a relationship exists between radius and concentration, which allows to express the saturation ratio of the droplet as a function of either one of these two parameters. The curves showing the complete behaviour of saturation ratio as a function of radius, for various sizes of NaCl nuclei, were previously presented for both wholly and partially dissolved salt. Here, the dependence of saturation ratio on droplet concentration, rather than on its radius, is examined and plotted for various NaCl nuclei. The occurrence of an analogous, but X-shaped, hysteresis phenomenon, characterizing the behaviour of the solution concentration in a growing-shrinking cycle of a solution droplet under changing humidity, is evidenced and discussed. An insoluble spherical core is assumed to be always present inside the condensation nucleus, so that the onset of the sudden salt re-crystallization is triggered at a well defined concentration value.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

    PubMed

    Gu, Guoying; Zhu, Limin

    2010-08-01

    In this paper, an ellipse-based mathematic model is developed to characterize the rate-dependent hysteresis in piezoelectric actuators. Based on the proposed model, an expanded input space is constructed to describe the multivalued hysteresis function H[u](t) by a multiple input single output (MISO) mapping Gamma:R(2)-->R. Subsequently, the inverse MISO mapping Gamma(-1)(H[u](t),H[u](t);u(t)) is proposed for real-time hysteresis compensation. In controller design, a hybrid control strategy combining a model-based feedforward controller and a proportional integral differential (PID) feedback loop is used for high-accuracy and high-speed tracking control of piezoelectric actuators. The real-time feedforward controller is developed to cancel the rate-dependent hysteresis based on the inverse hysteresis model, while the PID controller is used to compensate for the creep, modeling errors, and parameter uncertainties. Finally, experiments with and without hysteresis compensation are conducted and the experimental results are compared. The experimental results show that the hysteresis compensation in the feedforward path can reduce the hysteresis-caused error by up to 88% and the tracking performance of the hybrid controller is greatly improved in high-speed tracking control applications, e.g., the root-mean-square tracking error is reduced to only 0.34% of the displacement range under the input frequency of 100 Hz. PMID:20815625

  3. Magneto-optic Kerr effect hysteresis loop measurements on rf-sputtered iron oxide thin films

    Microsoft Academic Search

    Guang-Jian You; D. P. Winters; Zeng-Jun Zhou; Yu Mei; H. L. Luo

    1987-01-01

    Hysteresis curves of Fe3O4 and ?-Fe2O3 films were obtained using magnetio-optic Kerr effect measurements. The polar Kerr rotation angles of Fe3O4 and ?-Fe2O3 at 632.8 nm were determined to be 4.8 and 3.0 min, respectively.

  4. Magneto-optic Kerr effect hysteresis loop measurements on rf-sputtered iron oxide thin films

    NASA Astrophysics Data System (ADS)

    You, Guang-Jian; Winters, D. P.; Zhou, Zeng-Jun; Mei, Yu; Luo, H. L.

    1987-04-01

    Hysteresis curves of Fe3O4 and ?-Fe2O3 films were obtained using magnetio-optic Kerr effect measurements. The polar Kerr rotation angles of Fe3O4 and ?-Fe2O3 at 632.8 nm were determined to be 4.8 and 3.0 min, respectively.

  5. “P” curves for micro-structural characterization of magnetic suspensions

    NASA Astrophysics Data System (ADS)

    Popa, Nicolae Calin; Siblini, Ali; Nader, Chadi

    2005-05-01

    The paper defines, describes, and presents the "P" curves for micro-structural characterization of the complex fluids, complex powders, and complex solid matrix, having magnetic properties. P curves are the first derivative (relative to the magnetic field strength) of the hysteresis curves relative to the saturation magnetization. They offer the possibility to investigate live biological materials without sample extraction.

  6. 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.

  7. New Phenomenon of the Hysteresis of 4He in Vycor Glass

    NASA Astrophysics Data System (ADS)

    Jin, Xin; Xu, Xiaonong; Yan, Yong; A, L. Thomson; D, F. Brewer; S, Haynes; N, Sharma

    1992-02-01

    The low temperature part of hysteresis curves of the freezing and melting processes of 4He in vycor glass with the lowest temperature 0.4K were measured, as the pressure ranged from 36.45 to 55.18 (105 Pa). Some novel characteristics of these curves were observed in such high temperature and pressure range. They may result from the existence of superfluid 4He.

  8. Direct hysteresis measurements on ferroelectret films by means of a modified Sawyer-Tower circuit

    NASA Astrophysics Data System (ADS)

    Qiu, Xunlin; Holländer, Lars; Wirges, Werner; Gerhard, Reimund; Cury Basso, Heitor

    2013-06-01

    Ferro- and piezo-electrets are non-polar polymer foams or film systems with internally charged cavities. Since their invention more than two decades ago, ferroelectrets have become a welcome addition to the range of piezo-, pyro-, and ferro-electric materials available for device applications. A polarization-versus-electric-field hysteresis is an essential feature of a ferroelectric material and may also be used for determining some of its main properties. Here, a modified Sawyer-Tower circuit and a combination of unipolar and bipolar voltage waveforms are employed to record hysteresis curves on cellular-foam polypropylene ferroelectret films and on tubular-channel fluoroethylenepropylene copolymer ferroelectret film systems. Internal dielectric barrier discharges (DBDs) are required for depositing the internal charges in ferroelectrets. The true amount of charge transferred during the internal DBDs is obtained from voltage measurements on a standard capacitor connected in series with the sample, but with a much larger capacitance than the sample. Another standard capacitor with a much smaller capacitance—which is, however, still considerably larger than the sample capacitance—is also connected in series as a high-voltage divider protecting the electrometer against destructive breakdown. It is shown how the DBDs inside the polymer cavities lead to phenomenological hysteresis curves that cannot be distinguished from the hysteresis loops found on other ferroic materials. The physical mechanisms behind the hysteresis behavior are described and discussed.

  9. Wavelet implementation of Preisach model of hysteresis

    Microsoft Academic Search

    Yunhe Yu; Zhengchu Xiao; En-Bing Lin; Nagi G. Naganathan

    1999-01-01

    Preisach model has enjoyed extensive applications in describing the hysteresis phenomena. However an important open question in the analysis of hysteresis using Preisach models is the determination of the model parameters. This is to determine the parameter of Preisach function and is referred as the identification problem. However, no general mathematical methods appear to be available for the identification of

  10. Void space modeling of mercury intrusion hysteresis in sandstone, paper coating, and other porous media

    SciTech Connect

    Matthews, G.P.; Ridgway, C.J. [Univ. of Plymouth (United Kingdom). Dept. of Environmental Sciences] [Univ. of Plymouth (United Kingdom). Dept. of Environmental Sciences; Spearing, M.C. [AEA Petroleum Services, Dorset (United Kingdom)] [AEA Petroleum Services, Dorset (United Kingdom)

    1995-04-01

    A void space network is presented for the simulation of mercury intrusion hysteresis in outcrop and reservoir sandstones and paper coatings. Three methods are described which allow the convergence of the simulation onto experiment, each finding the optimum pore and throat size distributions and connectivity according to different criteria. The simulated pore and throat size distributions are entirely different from the first derivatives of the intrusion curves which are commonly employed. The optimum void space networks, which have the correct porosity, are then used to simulate the hysteresis which occurs when the mercury is withdrawn. The effects of contact angle hysteresis and trapping within wide pores adjacent to narrow throats are demonstrated. Considerable trapping of mercury is found to occur because of snap-off effects, without invoking any dead-end pores. Similar networks have been used to simulate absolute gas permeability, tortuosity, diffusion, formation factor, and colloidal flow formation damage and can be applied to any porous medium.

  11. Hysteresis nonlinearity identification by using RBF neural network approach

    Microsoft Academic Search

    Mohsen Firouzi; Saeed Bagheri Shouraki; Mohammad Reza Zakerzadeh

    2010-01-01

    In systems with hysteresis behavior like magnetic cores, Piezo actuators, Shape Memory Alloy(SMA), we essentially need an accurate modeling of hysteresis either for design or performance evaluation; also in some control applications accurate system identification is needed. One of the famous methods of Hysteresis modeling is Preisach model. In this numerical method hysteresis is modeled by linear combination of smaller

  12. A high-performance hysteresis loop tracer

    Microsoft Academic Search

    Tadeusz Kulik; Howard T. Savage; Antonio Hernando

    1993-01-01

    A high-performance and inexpensive hysteresis loop tracer has been developed to measure quasistatic (0.02 Hz or less) hysteresis loops of soft ferromagnetic materials. It was applied very successfully to measure straight pieces of amorphous and nanocrystalline ribbons and amorphous wires. Especially high-magnetic-field resolution is required when nanocrystalline ferromagnets and amorphous wires are measured. Nanocrystalline materials exhibit very low coercivity (Hc=0.1–0.5

  13. 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.

  14. 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.

  15. Hysteresis in neural-type circuits

    Microsoft Academic Search

    N. El-Leithy; R. W. Newcomb

    1988-01-01

    The mechanism of generation of hysteresis in a neural-type cell is presented. To make the theory tractable, it is assumed that the hysteresis determining MOS transistors operate in their square-law region when turned on. A set of equations is obtained that can be used for the design of MOS transistor neural-type cells which give pulse code modulation for the coding

  16. 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.

  17. Hysteresis during contact angles measurement.

    PubMed

    Diaz, M Elena; Fuentes, Javier; Cerro, Ramon L; Savage, Michael D

    2010-03-15

    A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle. PMID:20060981

  18. A new ferromagnetic hysteresis model for soft magnetic composite materials

    NASA Astrophysics Data System (ADS)

    Zidari?, Bogomir; Miljavec, Damijan

    2011-01-01

    A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.

  19. 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.

  20. Anisotropic electrical conductivity, phase transition and thermal hysteresis of a charge-transfer salt dibutylammonium bis-7,7,8,8-tetracyanoquinodimethane DBA(TCNQ)2

    NASA Astrophysics Data System (ADS)

    Long, Yun-Ze; Chen, Zhao-Jia; Peng, Hai-Lin; Liu, Zhong-Fan

    2008-06-01

    This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetracyanoquinodimethane [DBA (TCNQ)2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA (TCNQ)2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semiconducting behaviour and the room-temperature conductivities are highly anisotropic (?a = 3.63 × 10-4S/cm, ?b = 2.84 × 10-6S/cm, and ?c = 1.82 × 10-5S/cm). Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.

  1. 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.

  2. SPECIAL FEATURE Social hysteresis and ecological hysteresis Maja Schlu ter Heather Leslie Simon Levin

    E-print Network

    Leslie, Heather

    complex and often conflicting demands for water among different uses and users in a river basinSPECIAL FEATURE Social hysteresis and ecological hysteresis Maja Schlu¨ ter Æ Heather Leslie Æ Simon Levin Managing water-use trade-offs in a semi-arid river delta to sustain multiple ecosystem

  3. 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.

  4. 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.

  5. Mechanical Models of Friction That Exhibit Hysteresis, Stick-Slip, and the Stribeck Effect

    NASA Astrophysics Data System (ADS)

    Drincic, Bojana

    In this dissertation, we model hysteretic and friction phenomena without introducing friction or hysteresis per se. We use a combination of masses, springs, and dashpots and the frictional phenomena emerge as the result of their interaction. By using physical elements, we can understand the physical mechanisms that lead to hysteretic energy dissipation and phenomena, such as stick-slip behavior and the Stribeck effect. Furthermore, we study the origins of butterfly hysteresis, which arises in optics and ferromagnetism. We define the multiplay model for hysteresis with nonlocal memory, which consists of N mass/spring/dashpot with deadzone elements. The advantage of this model is that its hysteresis map can be inverted analytically. Second, we investigate the origins of stick-slip friction by developing an asperity-based friction model involving the frictionless contact between a body and a row of rigid, rotating bristles. This model exhibits hysteresis and quasi-stick-slip friction. The hysteretic energy-dissipation mechanism is the sudden release of the pivoted bristles. The discontinuous rotating bristle model is an approximation of the rotating bristle model that exhibits exact stick-slip and hysteresis. We next develop an asperity-based friction model in which the vertical motion of the body leads to the Stribeck effect. The friction model is hysteretic and the energy-dissipation mechanism is the sudden release of the compressed bristles. We show that this bristle model is a generalization of the LuGre model. The final contribution of this dissertation is a framework for relating butterfly-shaped hysteresis maps to simple hysteresis maps, which are typically easier to model and more amenable to control design. In particular, a unimodal mapping is used to transform simple loops to butterfly loops.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  7. Surface Aligned Magnetic Moments and Hysteresis of an Endohedral Single-Molecule Magnet on a Metal

    NASA Astrophysics Data System (ADS)

    Westerström, Rasmus; Uldry, Anne-Christine; Stania, Roland; Dreiser, Jan; Piamonteze, Cinthia; Muntwiler, Matthias; Matsui, Fumihiko; Rusponi, Stefano; Brune, Harald; Yang, Shangfeng; Popov, Alexey; Büchner, Bernd; Delley, Bernard; Greber, Thomas

    2015-02-01

    The interaction between the endohedral unit in the single-molecule magnet Dy2ScN @C80 and a rhodium (111) substrate leads to alignment of the Dy 4 f orbitals. The resulting orientation of the Dy2ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field. The x-ray magnetic circular dichroism is also angle dependent and signals strong magnetocrystalline anisotropy. This directly relates geometric and magnetic structure. Element specific magnetization curves from different coverages exhibit hysteresis at a sample temperature of ˜4 K . From the measured hysteresis curves, we estimate the zero field remanence lifetime during x-ray exposure of a submonolayer to be about 30 seconds.

  8. Surface aligned magnetic moments and hysteresis of an endohedral single-molecule magnet on a metal.

    PubMed

    Westerström, Rasmus; Uldry, Anne-Christine; Stania, Roland; Dreiser, Jan; Piamonteze, Cinthia; Muntwiler, Matthias; Matsui, Fumihiko; Rusponi, Stefano; Brune, Harald; Yang, Shangfeng; Popov, Alexey; Büchner, Bernd; Delley, Bernard; Greber, Thomas

    2015-02-27

    The interaction between the endohedral unit in the single-molecule magnet Dy_{2}ScN@C_{80} and a rhodium (111) substrate leads to alignment of the Dy 4f orbitals. The resulting orientation of the Dy_{2}ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field. The x-ray magnetic circular dichroism is also angle dependent and signals strong magnetocrystalline anisotropy. This directly relates geometric and magnetic structure. Element specific magnetization curves from different coverages exhibit hysteresis at a sample temperature of ?4??K. From the measured hysteresis curves, we estimate the zero field remanence lifetime during x-ray exposure of a submonolayer to be about 30 seconds. PMID:25768775

  9. Modeling and inverse feedforward control for conducting polymer actuators with hysteresis

    NASA Astrophysics Data System (ADS)

    Wang, Xiangjiang; Alici, Gursel; Tan, Xiaobo

    2014-02-01

    Conducting polymer actuators are biocompatible with a small footprint, and operate in air or liquid media under low actuation voltages. This makes them excellent actuators for macro- and micro-manipulation devices, however, their positioning ability or accuracy is adversely affected by their hysteresis non-linearity under open-loop control strategies. In this paper, we establish a hysteresis model for conducting polymer actuators, based on a rate-independent hysteresis model known as the Duhem model. The hysteresis model is experimentally identified and integrated with the linear dynamics of the actuator. This combined model is inverted to control the displacement of the tri-layer actuators considered in this study, without using any external feedback. The inversion requires an inverse hysteresis model which was experimentally identified using an inverse neural network model. Experimental results show that the position tracking errors are reduced by more than 50% when the hysteresis inverse model is incorporated into an inversion-based feedforward controller, indicating the potential of the proposed method in enabling wider use of such smart actuators.

  10. Root numbers of curves

    Microsoft Academic Search

    MARIA SABITOVA

    2004-01-01

    We generalize a theorem of D. Rohrlich concerning root numbers of elliptic curves over the field of rational numbers. Our result applies to curves of all higher genera over number fields. Namely, under certain conditions which naturally extend the conditions used by D. Rohrlich, we show that the root number associated to a smooth projective curve over a number field

  11. Hysteresis and calcium set-point for the calcium parathyroid hormone relationship in healthy horses

    Microsoft Academic Search

    Ramiro E. Toribio; Catherine W. Kohn; Richard A. Sams; Charles C. Capen; Thomas J. Rosol

    2003-01-01

    Abnormalities in calcium (Ca2+) homeostasis are reported in horses with several pathological conditions; however, there is little information on Ca2+ regulation in horses. The objectives of the present study were to determine the Ca2+ set-point in healthy horses, to determine whether the Ca2+\\/parathyroid hormone (PTH) response curves were characterized by hysteresis, and to determine if the order of experimentally induced

  12. 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.

  13. Ogive Curves

    NSDL National Science Digital Library

    2008-01-01

    This page contains a discussion of ogive curves, logistic regression curves, and architecture. Nice photographs of architectural applications are included. The classic Birthday Problems is included as an example of an ogive curve.

  14. The Impact of Shallow-Trench-Isolation Mechanical Stress on the Hysteresis Effect of Partially Depleted Silicon-on-Insulator n-Type Metal-Oxide-Semiconductor Field Effects

    NASA Astrophysics Data System (ADS)

    Luo, Jie-Xin; Chen, Jing; Chai, Zhan; Lü, Kai; He, Wei-Wei; Yang, Yan; Wang, Xi

    2014-12-01

    The impact of shallow trench isolation (STI) mechanical stress on the hysteresis effect in the output characteristics is measured in partially depleted (PD) silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistors (MOSFETs). We develop ID hysteresis, which is defined as the difference between ID versus VD forward sweep and reverse sweep. The fabricated devices show positive and negative peaks in ID hysteresis. The experimental results show that ID hysteresis declined as the STI mechanical stress increases. We also elaborate on the impact of STI mechanical stress on the ID hysteresis of PD SOI n-type MOSFETs.

  15. Study of the influence of structural hysteresis on polaron interactions of lightly doped poly(3-dodecylthiophene) with FeCl 3

    Microsoft Academic Search

    G. ?ík; L. Dlhá?; F. Šerše?; P. Rapta

    2007-01-01

    EPR, dc and ac magnetic measurements on lightly doped poly(3-dodecylthiophene) with FeCl3 are reported. The zero-field-cooled and field-cooled curves obtained by a SQUID magnetometer confirmed magnetic hysteresis, beginning close to the room temperature. Magnetic hysteresis is close-knit with structural irreversibility of polymeric chains. Structural irreversibility induces changes in proportions of diamagnetic, Pauli, Currie, and polaron magnetic contributions of the polymeric

  16. 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.

  17. 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.

  18. Analysis of a hysteresis motor with overexcitation

    SciTech Connect

    Kataoka, T.; Ishikawa, T.; Takahasi, T.

    1982-11-01

    The performance of a hysteresis motor can be improved greatly if it is overexcited for a short period when running at synchronous speed. The change in the magnetic state of the rotor hysteresis material, when the stator voltage is raised and then reduced to the original value, is described in detail. Based on this, a method for the calculation of the motor performance after overexcitation is proposed, and the effect of overexcitation on the motor performance is clarified by using this method. Good agreement is found between the calculated and the measured results.

  19. Effect of contact angle hysteresis on breakage of a liquid bridge

    NASA Astrophysics Data System (ADS)

    Chen, H.; Tang, T.; Amirfazli, A.

    2015-03-01

    In this paper, the importance of considering contact angle hysteresis (CAH) during the process of stretching and breaking a liquid bridge between two solid surfaces is addressed. We clearly show that due to the pinning of contact line at the end of the stretching stage, the contact angle between liquid bridge and surfaces cannot be simply assumed to have a constant value (e.g. receding contact angle, ? r ). Simulation results for stretching a liquid bridge with and without CAH, showed that the contact line pinning can lead to breakage at a larger surface separation and smaller value of pull-off force ( F p ). A systematic study about the effect of CAH and contact line pinning on the value of F p is provided. It is found that when one of the surfaces has a ? r larger than 90?, F p decreases with the increase of ? r on either surface delimiting the bridge. For the cases where ? r of both surfaces are smaller than 90?, significantly smaller F p is seen when contact line pinning occurs on both surfaces, as compared to F p when contact line pinning occurs only on one surface. This smaller F p is caused by more curved profile and later breakage of liquid bridge.

  20. "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…

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

    SciTech Connect

    Vagaggini, E.; Domergue, J.M.; Evans, A.G. [Univ. of California, Santa Barbara, CA (United States)

    1995-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Schmidbauer, E.

    1988-05-01

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

  3. Multiresolution curves

    Microsoft Academic Search

    Adam Finkelstein; David H. Salesin

    1994-01-01

    We describe a multiresolution curve representation, based on wavelets, that conveniently supports a variety of operations: smoothing a curve; editing the overall form of a curve while preserving its details; and approximating a curve within any given error tolerance for scan conversion. We present methods to support continuous levels of smoothing as well as direct manipulation of an arbitrary portion

  4. 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.

  5. SOLVING CURVED DETONATION RIEMANN PROBLEMS Bruce Bukiet

    E-print Network

    Bukiet, Bruce

    the one parameter family of behind states comprising the burned Hugoniot and wave curves. For curved and show how the curved detonation jump conditions can be solved to compute the curved detonation Hugoniot

  6. 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.

  7. 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.

  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. 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.

  10. Hysteresis loss in vector Preisach models

    Microsoft Academic Search

    E. Della Torre; E. Cardelli; L. H. Bennett

    2010-01-01

    Purpose – The magnetic modeling of materials has been focused on computing magnetization and forces in devices. With increasing efforts to make energy efficient devices, attention must now be paid to hysteresis losses in magnetizing processes. The purpose of this paper is to discuss the pertinent parameters that determine these losses and a method of identifying them. Design\\/methodology\\/approach – A

  11. Hysteresis regimes in fuel burning processes

    Microsoft Academic Search

    S. P. Bardakhanov; A. V. Potapkin

    1999-01-01

    The results of experimental studies of thennoacoustic processes in tubes with local heat release are presented. The heat supply was ensured either by heated grids in the tube or by burning of gasoline vapors or hydrogen in the singing flame regime. The boundaries of acoustic regimes and hysteresis regions are determined. An increase in power of thermal energy facilities and

  12. Hysteresis and transition in swirling nonpremixed flames

    Microsoft Academic Search

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

    2009-01-01

    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),

  13. Magnetic Hysteresis Loop Tracer Using Operational Amplifiers

    Microsoft Academic Search

    Homer Fay

    1972-01-01

    A magnetic hysteresis loop tracer has been built to measure the magnetic properties of small cylindrical samples of nonconductive ferromagnets. Applied fields of 10 000 Oe peak amplitude are obtained from a water cooled solenoid driven at 60 Hz, and the change in flux is detected with a coil on the sample. Two operational amplifiers convert the input variables to

  14. Role of hysteresis in stomatal aperture dynamics

    NASA Astrophysics Data System (ADS)

    Ramos, Antônio M. T.; Prado, Carmen P. C.

    2013-01-01

    Stomata are pores responsible for gas exchange in leaves. Several experiments indicate that stomata synchronize into clusters or patches. The patches’ coordination may produce oscillations in stomatal conductance. Previous studies claim to reproduce some experimental results. However, none was able to explain the variety of behavior observed in the stomatal dynamics. Recently, Ferraz and Prado suggested a realistic geometry of vein distribution. Although it reproduces the patches, no oscillation was observed and the patches remain static. Without exploring significant details, the authors stated that hysteresis in stomatal aperture could explain several experimental features. In this paper, the hysteresis hypothesis is further explored through the concept of hysteretic operators. We have shown that the hysteresis assumption is sufficient to obtain dynamical patches and oscillations in stomatal conductance. The robustness of this hypothesis is tested by using different hysteresis operators. The model analysis reveals a dependence between the period of oscillation in stomatal conductance and the water deficit between the leaf and the environment. This underlying feature of the model might inspire further experiments to test this hypothesis.

  15. Sci Show

    NSDL National Science Digital Library

    The Sci Show, an entertaining series of quirky YouTube videos, tackles topics ranging from â??How Do Polarized Sunglasses Workâ? to â??Strong Interaction: The Four Fundamental Forces of Physics.â? Most episodes are less than five minutes long, but they pack a wallop of handy science info. Anyone short on time but long on big questions will benefit from the series. Episodes will be helpful to teachers and parents looking to spark enthusiasm in young minds. Viewers may want to start with recent episodes like â??Todayâ??s Mass Extinction,â? and the â??Worldâ??s First See-Through Animalâ? and â??How Do Animals Change Color?â? before digging into the archives for gems like â??The Truth About Gingersâ? and â??The Science of Lying.â?

  16. 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.

  17. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

    and hysteresis inherent to ferro- elastic compounds, with emphasis placed on shape memory alloys. We formulate with experimental stress-strain data. Keywords: Ferroelastic hysteresis; shape memory alloy; domain wall theory. In shape memory alloys (SMAs), elastic hysteresis enables the materials to achieve very high work densities

  18. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

    and hysteresis inherent to ferro­ elastic compounds, with emphasis placed on shape memory alloys. We formulate with experimental stress­strain data. Keywords: Ferroelastic hysteresis; shape memory alloy; domain wall theory. In shape memory alloys (SMAs), elastic hysteresis enables the materials to achieve very high work densities

  19. Specification of distribution functions for magnetic hysteresis modeling

    Microsoft Academic Search

    A. Pruksanubal

    2009-01-01

    This paper describes the combination of different statistical distributions to apply in the Preisach hysteresis model. The model is able to represent the hysteresis property of the ferromagnetic material if its distribution function is well determined. Various distributions, such as Gaussian, Weibull, Cauchy, Laplace, Rayleigh, etc., are combined to produce different distribution functions and to simulate the hysteresis loops. Finally,

  20. Piezomagnetic hysteresis as a non-destructive measure of the metal fatigue process

    Microsoft Academic Search

    S. Bao; W. L. Jin; M. F. Huang; Y. Bai

    2010-01-01

    The primary goal of this research is to investigate the piezomagnetic fields surrounding AISI 1018 steel specimens under repeated loads. 11 strain controlled fatigue tests were carried out to study the fatigue behavior of AISI 1018 steel samples. Experimental results show that the piezomagnetic hysteresis traces change systematically with the progression of fatigue. Extensive analysis of the test data show

  1. Thermal hysteresis of permeability and transport properties of Mn substituted Mg Cu Zn ferrites

    NASA Astrophysics Data System (ADS)

    Manjurul Haque, M.; Huq, M.; Hakim, M. A.

    2008-03-01

    Mn substituted Mg-Cu-Zn ferrites of composition Mg0.35Cu0.20Zn0.45O(Fe2-xMnx O3)0.97 have been prepared by the standard double sintering ceramic technique. X-ray diffraction patterns of the samples showed single phase cubic spinel structure without any detectable impurity phases. The lattice constant is found to increase linearly with increase in Mn3+ ion concentration obeying Vegard's law. The initial permeability (?i) of the Mg-Cu-Zn ferrites exhibits thermal hysteresis when the temperature is cycled from above the Curie temperature TC to below. The sharp decrease of ?i at T = TC indicates that the samples have high homogeneity according to Globus et al. The Curie temperature TC of the studied ferrite system was determined from the ?i-T curves where the Hopkinson type of effect at the TC has been observed with the manifestation of a sharp fall in permeability. The Curie temperature TC is found to increase with increasing Mn content. Dc electrical resistivity increases significantly with the increase in Mn content. The ac resistivity (?ac) and dielectric constant (?') of the samples are found to decrease with increase in frequency, exhibiting normal ferrimagnetic behaviour. Dielectric relaxation peaks were observed for the frequency dependence of dielectric loss tangent curves. ?' increases as the temperature increases, which is the normal dielectric behaviour of the magnetic semiconductor ferrite. The observed variation of electrical and dielectric properties are explained on the basis of Fe2+/Fe3+ ionic concentration as well as the electronic hopping frequency between Fe2+ and Fe3+ ions in the present samples.

  2. Hysteresis modeling of Gd films and AFC thin-film recording media

    NASA Astrophysics Data System (ADS)

    Ktena, A.; Fotiadis, D. I.; Berger, A.; Massalas, C. V.

    2004-01-01

    This paper presents simulations of hysteresis processes in thin film media using 1D and 2D Preisach models. In the 2D version, a vector operator and superposition of angularly distributed models are used. The characteristic density of the material being modeled is reconstructed via a curve-fitting least-squares procedure that determines the parameters of a bivariate normal probability function density or a weighed mixture of normal densities based on major loop data only. The models have been identified for several samples of Gd films annealed at various temperatures and AFC thin-film recording media consisting of a hard and a soft phase antiferromagnetically coupled. The major and minor hysteresis loops calculated for all samples are in good agreement with experimental data.

  3. 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.

  4. A high-performance hysteresis loop tracer

    NASA Astrophysics Data System (ADS)

    Kulik, Tadeusz; Savage, Howard T.; Hernando, Antonio

    1993-05-01

    A high-performance and inexpensive hysteresis loop tracer has been developed to measure quasistatic (0.02 Hz or less) hysteresis loops of soft ferromagnetic materials. It was applied very successfully to measure straight pieces of amorphous and nanocrystalline ribbons and amorphous wires. Especially high-magnetic-field resolution is required when nanocrystalline ferromagnets and amorphous wires are measured. Nanocrystalline materials exhibit very low coercivity (Hc=0.1-0.5 A/m). The error of Hc measurement using this tracer does not exceed 0.05 A/m even though the amorphous wires have very small cross section (0.008 mm2). The examples of hysteresis loops measured at low (50 A/m) and high magnetic field (14 kA/m) are presented. The apparatus consists of an IBM-compatible computer equipped with 12 bit analog-to-digital and digital-to-analog converters, bipolar power supply, fluxmeter, solenoid and a pickup coil connected to a compensation coil. This equipment is free of 50 Hz noise, a significant problem in the performance of low-frequency loop tracers. The software was developed to enable measurement and immediate display of the M-H hysteresis loop. Previous loops also can be displayed and printed. Calibration of the setup is also possible. In the case of straight samples the measurements are followed by calculation of demagnetization factor Nd(calc.) using the ellipsoidal approximation of the sample shape. It was found that the experimental value of Nd is 30%-40% of the calculated value Nd(calc.) for the ribbons studied. Higher values of Nd correspond to the thicker ribbons where better agreement was obtained.

  5. Hysteresis in the T=0 random-field Ising model: Beyond metastable dynamics

    NASA Astrophysics Data System (ADS)

    Salvat-Pujol, Francesc; Vives, Eduard; Rosinberg, Martin-Luc

    2009-06-01

    We present a numerical study of the zero-temperature response of the Gaussian random-field Ising model to a slowly varying external field, allowing the system to be trapped in microscopic configurations that are not fully metastable. This modification of the standard single-spin-flip dynamics results in an increase in dissipation (hysteresis) somewhat similar to that observed with a finite driving rate. We then study the distribution of avalanches along the hysteresis loop and perform a finite-size scaling analysis that shows good evidence that the critical exponents associated to the disorder-induced phase transition are not modified.

  6. Floppy Curves with Applications to Real Algebraic Curves

    Microsoft Academic Search

    Patrick M. Gilmer

    1996-01-01

    We show how one may sometimes perform singular ambient surgery on the complex\\u000alocus of a real algebraic curve and obtain what we call a floppy curve. A\\u000afloppy curve is a certain kind of singular surface in CP(2), more general than\\u000athe complex locus of a real nodal curve. We derive analogs for floppy curves of\\u000aknown restrictions on

  7. Perceptual hysteresis as a marker of perceptual inflexibility in schizophrenia.

    PubMed

    Martin, Jean-Rémy; Dezecache, Guillaume; Pressnitzer, Daniel; Nuss, Philippe; Dokic, Jérôme; Bruno, Nicolas; Pacherie, Elisabeth; Franck, Nicolas

    2014-11-01

    People with schizophrenia are known to exhibit difficulties in the updating of their current belief states even in the light of disconfirmatory evidence. In the present study we tested the hypothesis that people with schizophrenia could also manifest perceptual inflexibility, or difficulties in the updating of their current sensory states. The presence of perceptual inflexibility might contribute both to the patients' altered perception of reality and the formation of some delusions as well as to their social cognition deficits. Here, we addressed this issue with a protocol of auditory hysteresis, a direct measure of sensory persistence, on a population of stabilized antipsychotic-treated schizophrenia patients and a sample of control subjects. Trials consisted of emotional signals (i.e., screams) and neutral signals (i.e., spectrally-rotated versions of the emotional stimuli) progressively emerging from white noise - Ascending Sequences - or progressively fading away in white noise - Descending Sequences. Results showed that patients presented significantly stronger hysteresis effects than control subjects, as evidenced by a higher rate of perceptual reports in Descending Sequences. The present study thus provides direct evidence of perceptual inflexibility in schizophrenia. PMID:25147080

  8. Control of deep-hysteresis aeroengine compressors. II. Design of control laws

    Microsoft Academic Search

    Miroslav KrstiC; Hsin-Hsiung Wang

    1997-01-01

    In this paper we continue the development of a methodology for control of deep-hysteresis compressors initiated in a companion paper. We develop a family of controllers which are applicable not only to the particular model presented in Part I of this paper, but also to general Moore-Greitzer type models with arbitrary compressor characteristics. For each of our controllers we show

  9. Transforming Curves into Curves with the Same Shape.

    ERIC Educational Resources Information Center

    Levine, Michael V.

    Curves are considered to have the same shape when they are related by a similarity transformation of a certain kind. This paper extends earlier work on parallel curves to curves with the same shape. Some examples are given more or less explicitly. A generalization is used to show that the theory is ordinal and to show how the theory may be applied…

  10. CPR: curved planar reformation

    Microsoft Academic Search

    Armin Kanitsar; Dominik Fleischmann; Rainer Wegenkittl; Petr Felkel; Meister Eduard Gröller

    2002-01-01

    Visualization of tubular structures such as blood vessels is an important topic in medical imaging. One way to display tubular structures for diagnostic purposes is to generate longitudinal cross-sections in order to show their lumen, wall, and surrounding tissue in a curved plane. This process is called Curved Planar Reformation (CPR). We present three different methods to generate CPR images.

  11. Conformational Electroresistance and Hysteresis in Nanoclusters

    SciTech Connect

    Li, Xiangguo [University of Florida, Gainesville; Zhang, Xiaoguang [ORNL; Cheng, Hai-Ping [University of Florida

    2014-01-01

    Among many mechanisms proposed for electroresistance, ones involving structural changes are the least understood because of challenges of controllability and repeatability. Yet structural changes can cause dramatic changes in electronic properties, leading to multiple ways in which conduction paths can be opened and closed, not limited to filament movement or variation in molecular conductance. Here we show at least another way: conformational dependence of the Coulomb charging energy of a nanocluster, where charging induced conformational distortion changes the blockade voltage, which in turn leads to a giant electroresistance. This 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 phenomenon of tunneling electroresistance. The new mechanism also provides a better controlled and repeatable platform to study conformational electroresistance.

  12. A new index to quantify hysteresis at the runoff event timescale

    NASA Astrophysics Data System (ADS)

    Zuecco, Giulia; Penna, Daniele; van Meerveld, Ilja; Borga, Marco

    2015-04-01

    Hysteresis is a non-linear loop-like behavior that is common in natural systems. Hysteresis is common in the relation between streamflow and a number of other hydrologic variables, e.g., groundwater levels, soil moisture, extent of the saturated area, and sediment and solute concentrations. Analysis of these hysteretic patterns at the event time scale can lead to a better understanding of the processes underlying the catchment hydrological response. Hysteretic patterns can also be used for model calibration and testing. Several indexes have been developed to analyze hysteresis and quantify the direction and the extent of the loops, particularly to determine hysteresis in the relation between sediment concentrations and runoff. However, they typically suffer from a degree of subjectivity, do not take into account complex hysteretic patterns and are therefore not always applicable to describe other hysteretic relations as well. Therefore, we present a new versatile index for the quantification of a wide range hysteretic loops between hydrological variables at the runoff event timescale and test the sensitivity of the index to the temporal resolution of the measurement data and measurement errors. The conceptual development of the new hysteresis index is based on i) a normalization to compare hysteretic loops at different space- and timescales, and ii) the computation of the slopes of segments connecting the initial state to observations of the independent variable. The index provides information on the direction, the extent and the shape of the hysteretic loops. The index was tested with hydrological data from three experimental catchments in Northern Italy. Hysteretic relations between streamflow (the independent variable) and four different dependent variables (soil moisture, groundwater level, isotopic composition of stream water and electrical conductivity of stream water) were correctly identified and quantified by the index. The objective quantification of hysteresis by the index allowed for the robust classification of hysteresis in datasets and thus to determine differences in hydrological responses for different events. The index also captured the switch in the direction of the hysteretic relation between soil moisture and streamflow with changes in event size and antecedent wetness conditions well. Finally, the sensitivity analyses showed that the index was little affected by the temporal resolution of the measurements and random errors in the input data. Keywords: hysteresis index; hysteretic loops; streamflow; soil moisture; seasonal dynamics; sensitivity analysis

  13. Theory of the hysteresis loop in ferromagnets 

    E-print Network

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

    1999-01-01

    for the inter- face profile Z(x,t)5 ^ Z(x,t) & jv ,tv on large scales is given by 1 geff ]Z ]t 5G? 2Z1h2hp1heff~x,vt !. ~9! Here ^& jv ,tv denotes the spatial and time average over scales jv and tv , respectively, and heff is the renormalized... a brief review of HLA scaling results, see Ref. 9!. The scaling behavior of the HLA was first reported in the pioneer work1 for three-dimensional ~3D! magnets. While there exists an extended literature on the hysteresis of 3D magnets...

  14. Mechano-electric optoisolator transducer with hysteresis

    NASA Astrophysics Data System (ADS)

    Ciuru?, I. M.; Dimian, M.; Graur, A.

    2011-01-01

    This article presents a theoretical and experimental study of designing a mechano-electric optoisolator transducer with hysteresis. Our research is centred upon designing transducers on the basis of optical sensors, as photoelectric conversions eliminate the influence of electromagnetic disturbances. Conversion of the rotation/translation motions into electric signals is performed with the help of a LED-photoresistor Polaroid optocoupler. The driver of the optocoupler's transmitter module is an independent current source. The signal conditioning circuit is a Schmitt trigger circuit. The device is designed to be applied in the field of automation and mechatronics.

  15. Hysteresis prediction inside magnetic shields and application

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  16. Hysteresis prediction inside magnetic shields and application.

    PubMed

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

    2014-07-01

    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. PMID:25085183

  17. 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.

  18. Feedforward Controller of Ill-Conditioned Hysteresis Using Singularity-Free Prandtl-Ishlinskii Model.

    PubMed

    Tan, U-Xuan; Latt, Win Tun; Shee, Cheng Yap; Riviere, Cameron N; Ang, Wei Tech

    2009-10-01

    Piezoelectric, magnetostrictive, and shape memory alloy actuators are gaining importance in high-frequency precision applications constrained by space. Their intrinsic hysteretic behavior makes control difficult. The Prandtl-Ishlinskii (PI) operator can model hysteresis well, albeit a major inadequacy: the inverse operator does not exist when the hysteretic curve gradient is not positive definite, i.e., ill condition occurs when slope is negative. An inevitable tradeoff between modeling accuracy and inversion stability exists. The hysteretic modeling improves with increasing number of play operators. But as the piecewise continuous interval of each operator reduces, the model tends to be ill-conditioned, especially at the turning points. Similar ill-conditioned situation arises when these actuators move heavy loads or operate at high frequency. This paper proposes an extended PI operator to map hysteresis to a domain where inversion is well behaved. The inverse weights are then evaluated to determine the inverse hysteresis model for the feedforward controller. For illustration purpose, a piezoelectric actuator is used. PMID:19936032

  19. Flow-duration curves

    USGS Publications Warehouse

    Searcy, James Kincheon

    1959-01-01

    The flow-duration curve is a cumulative frequency curve that shows the percent of time specified discharges were equaled or exceeded during a given period. It combines in one curve the flow characteristics of a stream throughout the range of discharge, without regard to the sequence of occurrence. If the period upon which the curve is based represents the long-term flow of a stream, the curve may be used to predict the distribution of future flows for water- power, water-supply, and pollution studies. This report shows that differences in geology affect the low-flow ends of flow-duration curves of streams in adjacent basins. Thus, duration curves are useful in appraising the geologic characteristics of drainage basins. A method for adjusting flow-duration curves of short periods to represent long-term conditions is presented. The adjustment is made by correlating the records of a short-term station with those of a long-term station.

  20. 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.

  1. Light Curves

    NSDL National Science Digital Library

    2013-02-12

    This is a game about light curves that will test your ability to figure out things about an asteroid from just a graph of its brightness. Astronomers use telescopes to collect light curves - measurements of the brightness of distant asteroids over time. It is part of the Killer Asteroids Web Site. The site also features a background overview of the differences between asteroids and comets, information on different types of asteroids (rubble piles vs monoliths), a discussion of how at risk Earth really is to an asteroid or comet impact, and background information on light curves.

  2. space curves and surfaces 1 Plotting Space Curves

    E-print Network

    Verschelde, Jan

    the twisted cubic give the azimuth : -30 give the elevation : 10 Scientific Software (MCS 507 L-16) space=30, elev=30) plt.show() Scientific Software (MCS 507 L-16) space curves and surfaces 2 October 2013space curves and surfaces 1 Plotting Space Curves the twisted cubic with matplotlib four subplots

  3. Connecting curves for dynamical systems

    E-print Network

    R. Gilmore; Jean-Marc Ginoux; Timothy Jones; C. Letellier; U. S. Freitas

    2010-03-08

    We introduce one dimensional sets to help describe and constrain the integral curves of an $n$ dimensional dynamical system. These curves provide more information about the system than the zero-dimensional sets (fixed points) do. In fact, these curves pass through the fixed points. Connecting curves are introduced using two different but equivalent definitions, one from dynamical systems theory, the other from differential geometry. We describe how to compute these curves and illustrate their properties by showing the connecting curves for a number of dynamical systems.

  4. Tripod configurations of curves

    NASA Astrophysics Data System (ADS)

    Chen, Eric; Lourie, Nick

    2015-03-01

    Tripod configurations of plane curves, formed by certain triples of normal lines coinciding at a point, were introduced by Tabachnikov, who showed that C2 closed convex curves possess at least two tripod configurations. Later, Kao and Wang established the existence of tripod configurations for C2 closed locally convex curves. In this paper we generalize these results, answering a conjecture of Tabachnikov on the existence of tripod configurations for all closed plane curves by proving existence for a generalized notion of tripod configuration. We then demonstrate the existence of the natural extensions of these tripod configurations to the spherical and hyperbolic geometries for a certain class of convex curves, and discuss an analogue of the problem for regular plane polygons.

  5. 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.

  6. Preisach modeling of piezoceramic and shape memory alloy hysteresis

    Microsoft Academic Search

    Declan Hughes; John T. Wen

    1995-01-01

    Smart materials such as piezoceramics and shape memory alloys (SMAs) exhibit significant hysteresis and in order to estimate the effect on open and closed loop control a suitable model is needed. One promising candidate is the Preisach independent domain hysteresis model that is characterized by the congruent minor loop and wiping out properties. Comparable minor loop and decaying oscillation test

  7. Hysteresis Modeling in An ElectroMagnetic Transients Program

    Microsoft Academic Search

    James Frame; Narendra Mohan; Tsu-huei Liu

    1982-01-01

    This paper describes an algorithm for representing the transformer hysteresis. This algorithm is useful under transient conditions and has the capability of representing minor loops. It allows the multi-valued hysteresis behavior to be represented as a linear element at each instant of time. This algorithm has been implemented into the BPA Electro-Magnetic Transients Program (EMTP), which is widely used on

  8. Potbellies, wasp-waists, and superparamagnetism in magnetic hysteresis

    Microsoft Academic Search

    L. Tauxe; T. A. T. Mullender; T. Pick

    1996-01-01

    Because the response of a magnetic substance to an applied field depends strongly on the physical properties of the material, much can be learned by monitoring that response through what is known as a ``magnetic hysteresis loop.'' The measurements are rapid and quickly becoming part of the standard set of tools supporting paleomagnetic research. Yet the interpretation of hysteresis loops

  9. Coupled magnetoelastic theory of magnetic and magnetostrictive hysteresis

    Microsoft Academic Search

    Martin J. Sablik; David C. Jiles

    1993-01-01

    It is demonstrated that hysteresis in the magnetostriction k is coupled to hysteresis in the magnetization M because of the dependence of the magnetostriction on the magnetization. At the same time, when stress is present, the magnetization is in turn coupled to the behavior of the part of the magnetostriction associated with domain moment rotation. An expression for the magnetostriction

  10. Spring Model of Hysteresis Applied to Tape-Wound Cores

    Microsoft Academic Search

    John A. Baldwin; Jay S. Bayne; Thomas R. Calkins

    1971-01-01

    The theory of the spring model of hysteresis is compared with experiment for a number of magnetic materials. The properties of the spring model as they relate to minor hysteresis loops are summarized. Loops from tape-wound cores of various materials are compared with these predictions to see if the cores obey the model. It is found that some cores, square

  11. A Free Energy Model for Hysteresis in Ferroelectric Materials

    E-print Network

    A Free Energy Model for Hysteresis in Ferroelectric Materials Ralph C. Smith Stefan Seelecke.ncsu.edu Abstract This paper provides a theory for quantifying the hysteresis and constitutive nonlinearities in homogenization techniques. In the first step of the model development, Helmholtz and Gibbs free energy relations

  12. Impact of relative permeability hysteresis on geological CO2 storage

    Microsoft Academic Search

    R. Juanes; E. J. Spiteri; F. M. Orr Jr; M. J. Blunt

    2006-01-01

    Relative permeabilities are the key descriptors in classical formulations of multiphase flow in porous media. Experimental evidence and an analysis of pore-scale physics demonstrate conclusively that relative permeabilities are not single functions of fluid saturations and that they display strong hysteresis effects. In this paper, we evaluate the relevance of relative permeability hysteresis when modeling geological CO2 sequestration processes. Here

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

    E-print Network

    frequency, temperature, and stress dependencies which makes it applicable for a wide range of transducer through comparison with experimental data. i #12;1 Introduction Hysteresis and constitutive nonlinearities and biomedical applications. In some regimes, hysteresis can be mitigated through restricted input levels

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

    Microsoft Academic Search

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

    2008-01-01

    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

  15. International Workshop on Multi-Rate Processes and Hysteresis

    Microsoft Academic Search

    Michael P Mortell; Robert E OMalley; Alexei Pokrovskii; Dmitrii Rachinskii; Vladimir A Sobolev

    2008-01-01

    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

  16. Performance Calculation of High Temperature Superconducting Hysteresis Motor Using Finite Element Method

    NASA Astrophysics Data System (ADS)

    Konar, G.; Chakraborty, N.; Das, J.

    Hysteresis motors being capable of producing a steady torque at low speeds and providing good starting properties at loaded condition became popular among different fractional horse power electrical motors. High temperature superconducting materials being intrinsically hysteretic are suitable for this type of motor. In the present work, performance study of a 2-pole, 50 Hz HTS hysteresis motor with conventional stator and HTS rotor has been carried out numerically using finite element method. The simulation results confirm the ability of the segmented HTS rotor with glued circular sectors to trap the magnetic field as high as possible compared to the ferromagnetic rotor. Also the magnetization loops in the HTS hysteresis motor are obtained and the corresponding torque and AC losses are calculated. The motor torque thus obtained is linearly proportional to the current which is the common feature of any hysteresis motor. Calculations of torques, current densities etc are done using MATLAB program developed in-house and validated using COMSOL Multiphysics software. The simulation result shows reasonable agreement with the published results.

  17. 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.

  18. Numerical determination of hysteresis parameters for the modeling of magnetic properties using the theory of ferromagnetic hysteresis

    Microsoft Academic Search

    D. C. Jiles; J. B. Thoelke; M. K. Devine

    1992-01-01

    The authors describe how the various model parameters needed to describe hysteresis on the basis of the Jiles-Atherton theory can be calculated from experimental measurements of the coercivity, remanence, saturation magnetization, initial anhysteretic susceptibility, initial normal susceptibility, and maximum differential susceptibility. The determination of hysteresis parameters based on this limited set of magnetic properties is of the most practical use

  19. 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.

  20. Strain-electric field hysteresis measurement in a Pb0.65Ba0.35Nb2O6 thin film using optical reflection

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Wood, Lowell T.; Miller, John H., Jr.; Strikovski, Mikhail

    2002-07-01

    We present a simple method using direct laser beam reflection from the MgO substrate of a PBN:65 thin film to measure strain-electric field hysteresis produced by electric field-induced bending. We obtained both the strain-electric field and time-electric field relationships from these hysteresis curves. In addition, we determined time constants for strain saturation, obtained a quadratic relationship between strain and electric field, and calculated a value of 0.000 875 mum2/V2 for the electrostrictive constant.

  1. A constitutive model for the frequency dependence of magnetic hysteresis

    NASA Astrophysics Data System (ADS)

    Ho, Kwangsoo

    2014-10-01

    The magnetic properties of materials are characterized by the variation of flux density with magnetic field. The hysteresis loop is generally dependent on the frequency of excitation. It is well known that the dependence is attributed to the effects of eddy current loss and anomalous (excess) loss. The present work deals with a new approaching method to model the frequency dependence of magnetic hysteresis within the framework of internal state variable theory, the fundamental structure of which is originally based on viscoplasticity theory in continuum mechanics. The hysteresis equations are formulated to be consistent with the general principles of irreversible thermodynamics with internal variables.

  2. 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.

  3. A statistical mechanical description of metastable states and hysteresis in the 3D soft-spin random-field model at T = 0

    NASA Astrophysics Data System (ADS)

    Rosinberg, M. L.; Tarjus, G.

    2010-12-01

    We present a formalism for computing the complexity of metastable states and the zero-temperature magnetic hysteresis loop in the soft-spin random-field model in finite dimensions. The complexity is obtained as the Legendre transform of the free energy associated with a certain action in replica space and the hysteresis loop above the critical disorder is defined as the curve in the field-magnetization plane where the complexity vanishes; the nonequilibrium magnetization is therefore obtained without having to follow the dynamical evolution. We use approximations borrowed from condensed-matter theory and based on assumptions on the structure of the direct correlation functions (or proper vertices), such as a local approximation for the self-energies, to calculate the hysteresis loop in three dimensions, the correlation functions along the loop, and the second moment of the avalanche-size distribution.

  4. Modelling hysteresis in magnetically ordered materials

    NASA Astrophysics Data System (ADS)

    Song, Tiancheng

    2003-06-01

    This thesis presents a generalized version of the Preisach model of hysteresis which is designed to describe the temperature dependence and field dependence of the irreversible response of magnetically ordered materials everywhere below their critical temperature Tc. The model decomposes the magnetizing process into a sequence of Barkhausen events, each of which is represented by a double well potential with moment mu two states ? = +/-mu, a dissipation energy Wd = mu hc and a stored energy Ws = 2muhi. A given magnetic material is characterized by an ensemble of Barkhausen elements with a distribution of characteristic fields p(hc, hi). The distribution is allowed to vary with temperature in order to reflect intrinsic variations with temperature of the anisotropy and pinning mechanisms, in such a way that the coercive field distribution collapses into a delta-function delta( hc) as T approaches Tc from below. Thermal fluctuations are represented by a thermal viscosity field h*T = (kBT/mu)ln( texp/tau0). The model was used to simulate numerically various standard experimental response functions, including the temperature dependence of the zero field cooled moment in a fixed applied field ha, the temperature dependence of the field cooled moment in a fixed applied field, initial magnetizing and major hysteresis loop isotherms, and remanences, and the influence of each model parameter on the magnetic response functions was studied systematically. The model simulation sidentified the ratio eta of the mean zero temperature dissipation barrier W¯d(0) to the critical thermal fluctuation energy Wc = k BTcln(texp/tau 0) ass an important parameter which influences the principal structural characteristics of the response, and which can be used to classify materials as fluctuation-dominated or anisotropy-dominated. The model was applied to the analysis of the measured response functions five systems, two nanoparticulate systems, Fe/SiO 2 and NiFe2O 4, which were fluctuation-dominated, and three ferromagnetic perovskites SrRuO3, La0.5Sr 0.5-CoO3, and La0.7 Sr0.3MnO3, which were anisotropy-dominated. The analysis yielded the spectrum of Barkhausen characteristic fields p(hc, hi, T) and the Barkhausen moment mu(T), from which it is possible to reconstruct a physical picture of the evolution of the Barkhausen free energy barriers with temperature, as well as some description of the reversible component of the response.

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

    Microsoft Academic Search

    Faa-Jeng Lin; Hsin-Jang Shieh; Po-Kai Huang; Li-Tao Teng

    2006-01-01

    Because the control performance of a piezoactuator is always severely deteriorated due to hysteresis effect, an adaptive control with hysteresis estimation and compensation using recurrent fuzzy neural network (RFNN) is proposed in this study to improve the control performance of the piezo-actuator. A new hysteresis model by modifying and parameterizing the hysteresis friction model is proposed. Then, the overall dynamics

  6. 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 ...

  7. 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.

  8. Modeling and analysis of multiclass thresholdbased queues with hysteresis using

    E-print Network

    Tuffin, Bruno

    behaviour. Hysteresis is also inserted, so that the control mechanism will not switch too much. One motiva terms of throughput, delay or jitter for instance) are required for different applications such as video

  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. On the question of hysteresis in Hall magnetohydrodynamic reconnection

    SciTech Connect

    Sullivan, Brian P.; Bhattacharjee, A.; Huang Yimin [Center for Integrated Computation and Analysis of Reconnection and Turbulence, University of New Hampshire, Space Science Center, Durham, New Hampshire 03824 (United States)

    2010-11-15

    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.

  11. 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.

  12. 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

  13. Hysteresis phenomena of a Macroscopic Fundamental Diagram in freeway networks

    Microsoft Academic Search

    Nikolas Geroliminis; Jie Sun

    2011-01-01

    Observations of traffic pairs of flow vs. density or occupancy for individual locations in freeways or arterials are usually scattered about an underlying curve. Recent observations from empirical data in arterial networks showed that in some cases by aggregating the highly scattered plots of flow vs. density from individual loop detectors, the scatter almost disappears and well-defined macroscopic relations exist

  14. Hysteresis Phenomena of a Macroscopic Fundamental Diagram in Freeway Networks

    Microsoft Academic Search

    Nikolas Geroliminis; Jie Sun

    2011-01-01

    Observations of traffic pairs of flow vs. density or occupancy for individual locations in freeways or arterials are usually scattered about an underlying curve. Recent observations from empirical data in arterial networks showed that in some cases by aggregating the highly scattered plots of flow vs. density from individual loop detectors, the scatter almost disappears and well-defined macroscopic relations exist

  15. 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.

  16. Controlling hysteresis in superconducting constrictions with a resistive shunt

    NASA Astrophysics Data System (ADS)

    Kumar, Nikhil; Winkelmann, C. B.; Biswas, Sourav; Courtois, H.; Gupta, Anjan K.

    2015-07-01

    We demonstrate control of the thermal hysteresis in superconducting constrictions by adding a resistive shunt. In order to prevent thermal relaxation oscillations, the shunt resistor is placed in close proximity to the constriction, making the inductive current-switching time smaller than the thermal equilibration time. We investigate the current–voltage characteristics of the same constriction with and without the shunt-resistor. The widening of the hysteresis-free temperature range is explained on the basis of a simple model.

  17. Hysteresis and interfacial energies in smooth-walled microfluidic channels

    Microsoft Academic Search

    Yihong Liu; D. D. Nolte; L. J. Pyrak-Nolte

    2011-01-01

    Hysteresis in the capillary pressure-saturation relationship (Pc–Sw) for a porous medium has contributions from the complex geometry of the pore network as well as the physical chemistry of the grain surfaces. To isolate the role of wettability on hysteresis, we fabricated microfluidic cells that contain a single wedge-shaped channel that simulates a single pore throat. Using confocal microscopy of the

  18. HYSTERESIS OF BACKFLOW IMPRINTED IN COLLIMATED JETS

    SciTech Connect

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

    2010-01-20

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

  19. Hysteresis of Backflow Imprinted in Collimated Jets

    E-print Network

    Mizuta, Akira; Nagakura, Hiroki

    2009-01-01

    We report two different types of backflow from jets by performing 2D special relativistic hydrodynamical simulations. One is anti-parallel and quasi-straight to the main jet (quasi-straight backflow), and the other is bent path of the backflow (bent backflow). We find that the former appears when the head advance speed is comparable to or higher than the local sound speed at the hotspot while the latter appears when the head advance speed is slower than the sound speed bat the hotspot. Bent backflow collides with the unshocked jet and laterally squeezes the jet. At the same time, a pair of new oblique shocks are formed at the tip of the jet and new bent fast backflows are generated via these oblique shocks. The hysteresis of backflow collisions is thus imprinted in the jet as a node and anti-node structure. This process also promotes broadening of the jet cross sectional area and it also causes a decrease in the head advance velocity. This hydrodynamic process may be tested by observations of compact young je...

  20. 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.

  1. Adhesion hysteresis and friction at nanometer and micrometer lengths

    SciTech Connect

    Szoszkiewicz, Robert; Bhushan, Bharat; Huey, Bryan D.; Kulik, Andrzej J.; Gremaud, Gerard [Georgia Institute of Technology, School of Physics, 837 State Street, Atlanta, Georgia 30332 (United States); Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), Ohio State University, Columbus, Ohio 43210 (United States); Institute of Material Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Institute of Physics of Complex Matter, EPFL, CH-1015 Lausanne (Switzerland)

    2006-01-01

    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.

  2. Hysteresis and the single-phase metal-insulator transition in switchable YHx films

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

    Extraordinary large hysteresis effects in optical, electrical, and structural properties are observed in switchable mirrors based on thin yttrium hydride (YHx) films, deposited on quartz glass or sapphire. The pressure-composition isotherms of the YHx system between x=2 and 3 for absorption and desorption, determined electrochemically, differ by approximately three orders of magnitude. The optical transmittance exhibits a distinct minimum when loading the films from the dihydride to the trihydride state; however, upon unloading this minimum is absent. The desorption data are in good agreement with literature data on bulk yttrium, but the absorption results show large deviations. Most important for the metal-insulator transition is that during hydrogen loading YHx remains in a single hcp phase for x>2.1. The hysteresis is discussed in terms of strains (and consequently stress) at the interface between fcc dihydride and hcp trihydride.

  3. Introduction Elliptic curves

    E-print Network

    Kwak, Do Young

    Introduction Elliptic curves Modular curves Elliptic curves and modular forms Application to number theory y-coordinates of elliptic curves Dong Hwa Shin Department of Mathematical Sciences KAIST January 11, 2010 #12;Introduction Elliptic curves Modular curves Elliptic curves and modular forms

  4. Elastic hysteresis in human eyes is age dependent value.

    PubMed

    Ishii, Kotaro; Saito, Kei; Kameda, Toshihiro; Oshika, Tetsuro

    2012-06-19

    Background:? The elastic hysteresis phenomenon is observed when cyclic loading is applied to a viscoelastic system. The purpose of this study was to quantitatively evaluate elastic hysteresis in living human eyes against an external force. Design:? Prospective case series. Participants:? Twenty-four eyes of 24 normal human subjects (mean age: 41.5 ± 10.6 years) were recruited. Methods:? A non-contact tonometry process was recorded with a high-speed camera. Central corneal thickness (CCT), corneal thickness at 4 mm from the center, corneal curvature, and anterior chamber depth (ACD) were measured. Intraocular pressure (IOP) was also measured using Goldmann applanation tonometry (GAT) and dynamic contour tonometer (DCT). Main Outcome Measures:? Energy loss due to elastic hysteresis was calculated and graphed. Results:? The mean CCT was 552.5 ± 36.1 µm, corneal curvature was 7.84 ± 0.26 mm, and ACD was 2.83 ± 0.29 mm. The mean GAT-IOP was 14.2 ± 2.7 mmHg and DCT-IOP was 16.3 ± 3.5 mmHg. The mean energy loss due to elastic hysteresis was 3.90 × 10(-6) ± 2.49 × 10(-6) Nm. Energy loss due to elastic hysteresis correlated significantly with age (Pearson correlation coefficient = 0.596, p = 0.0016). There were no significant correlations between energy loss due to elastic hysteresis and other measurements. Conclusion:? Energy loss due to elastic hysteresis in the eyes of subjects was found to positively correlate with age, independent of anterior eye structure or IOP. Therefore, it is believed that the viscosity of the eye increases with age. © 2010 The Authors. Clinical and Experimental Ophthalmology © 2010 Royal Australian and New Zealand College of Ophthalmologists. PMID:22713246

  5. 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...

  6. Weak hysteresis in a simplified model of the L-H transition

    SciTech Connect

    Malkov, M. A.; Diamond, P. H. [Center for Astrophysics and Space Sciences and Department of Physics, University of California, San Diego, La Jolla, California 92093-0424 (United States)

    2009-01-15

    A simple one-field L-H transition model is studied in detail, analytically and numerically. The dynamical system consists of three equations coupling the drift wave turbulence level, zonal flow speed, and the pressure gradient. The fourth component, i.e., the mean shear velocity, is slaved to the pressure gradient. Bursting behavior, characteristic for predator-prey models of the drift wave - zonal flow interaction, is recovered near the transition to the quiescent H-mode (QH) and occurs as strongly nonlinear relaxation oscillations. The latter, in turn, arise as a result of Hopf bifurcation (limit cycle) of an intermediate fixed point (between the L- and H-modes). The system is shown to remain at the QH-mode fixed point even after the heating rate is decreased below the bifurcation point (i.e., hysteresis, subcritical bifurcation), but the basin of attraction of the QH-mode shrinks rapidly with decreasing power. This suggests that the hysteresis in the H-L transition may be less than that expected from S-curve models. Nevertheless, it is demonstrated that by shaping the heating rate temporal profile, one can reduce the average power required for the transition to the QH-mode.

  7. Hysteresis of gating underlines sensitization of TRPV3 channels.

    PubMed

    Liu, Beiying; Yao, Jing; Zhu, Michael X; Qin, Feng

    2011-11-01

    Vanilloid receptors of the transient receptor potential family have functions in thermal sensation and nociception. Among them, transient receptor potential vanilloid (TRPV)3 displays a unique property by which the repeated stimulation causes successive increases in its activity. The property has been known as sensitization and is observed in both native cells and cells heterologously expressing TRPV3. Transient increases in intracellular calcium levels have been implicated to play a key role in this process by mediating interaction of calmodulin with the channel. In support of the mechanism, BAPTA, a fast calcium chelator, accelerates the sensitization, whereas the slow chelator EGTA is ineffectual. Here, we show that the sensitization of TRPV3 also occurred independently of Ca(2+). It was observed in both inside-out and outside-out membrane patches. BAPTA, but not EGTA, has a direct potentiation effect on channel activation. Analogues of BAPTA lacking Ca(2+)-buffering capability were similarly effective. The stimulation-induced sensitization and the potentiation by BAPTA are distinguishable in reversibility. We conclude that the sensitization of TRPV3 is intrinsic to the channel itself and occurs as a result of hysteresis of channel gating. BAPTA accelerates the sensitization process by potentiating the gating of the channel. PMID:22006988

  8. Force chains and hysteresis in a 2D granular piston

    NASA Astrophysics Data System (ADS)

    Hartley, R. R.; Behringer, R. P.; Kolb, E.; Ovarlez, G.; Clement, E.

    2001-11-01

    We present photoelastic studies of force distributions and propagation in a 2D granular piston.footnote E. Kolb, et. al. Europhys. J. B. 8, 483-491 (1999). The particles, ~ 1/2 cm disks, are confined by rigid sidewalls and pushed against gravity by a piston at constant velocity in the range 10-150 ? m/s. Friction prevents the free rotation and displacement of particles within the bulk of the material and leads to the buildup of stress chains resisting motion. The local and global stress within the granular material can be extracted by placing the experiment between complimentary circular polarizers. We find that the initial preparation (where the particles rain down in bulk) gives a stress minimum in the middle and edges, while the stress is polarized and maximal along each sidewall. The 2D pressure saturates at a depth ~ 1/2 width, and uniform compressive loads show hysteresis within the bulk. Under shear, we present evidence of stick-slip dynamics and large-scale convection when the particles can mobilize after dilation.

  9. Hysteresis of gating underlines sensitization of TRPV3 channels

    PubMed Central

    Liu, Beiying; Yao, Jing; Zhu, Michael X.

    2011-01-01

    Vanilloid receptors of the transient receptor potential family have functions in thermal sensation and nociception. Among them, transient receptor potential vanilloid (TRPV)3 displays a unique property by which the repeated stimulation causes successive increases in its activity. The property has been known as sensitization and is observed in both native cells and cells heterologously expressing TRPV3. Transient increases in intracellular calcium levels have been implicated to play a key role in this process by mediating interaction of calmodulin with the channel. In support of the mechanism, BAPTA, a fast calcium chelator, accelerates the sensitization, whereas the slow chelator EGTA is ineffectual. Here, we show that the sensitization of TRPV3 also occurred independently of Ca2+. It was observed in both inside-out and outside-out membrane patches. BAPTA, but not EGTA, has a direct potentiation effect on channel activation. Analogues of BAPTA lacking Ca2+-buffering capability were similarly effective. The stimulation-induced sensitization and the potentiation by BAPTA are distinguishable in reversibility. We conclude that the sensitization of TRPV3 is intrinsic to the channel itself and occurs as a result of hysteresis of channel gating. BAPTA accelerates the sensitization process by potentiating the gating of the channel. PMID:22006988

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. The consequences of similarity of hysteresis loops for interpreting magnetic particle systems

    NASA Astrophysics Data System (ADS)

    Ruta, Sergiu; Hovorka, Ondrej; Booth, Ryan; Majetich, Sara; Chantrell, Roy

    2014-03-01

    One of the challenges in understanding interacting magnetic particle (MP) assemblies is the interpretation of their physical parameters from magnetization measurements. A common framework has been based on the Langevin function approach, applicable in the super-paramagnetic limit of weakly interacting MPs . If interactions are significant or in case of thermally blocked MPs the issue becomes complicated by the presence of memory effects and hysteresis, and the question of uniqueness of parameter identification arises. To study this question, we consider a kinetic Monte-Carlo model of dipolar interacting Stoner-Wohlfarth MP, including volume and anisotropy distributions. By applying the grid search methods combined with the least squares fitting approach we map the parameter regions of hysteresis loops indistinguishable within a statistical confidence. This allows to show that a unique extraction of model parameters is indeed possible only in a certain range of MP concentrations and temperatures. Thus the hysteresis loop similarity prohibits a reliable parameter identification - being a fundamental issue that may potentially be resolved only by devising different measurements protocols.

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

    NASA Astrophysics Data System (ADS)

    Hergt, Rudolf; Dutz, Silvio; Röder, Michael

    2008-09-01

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

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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 [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    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.

  1. Hydrogenation effect on the hysteresis properties of rapidly quenched Nd–Ho–Fe–Co–B alloys

    Microsoft Academic Search

    I. Tereshina; N. Kudrevatykh; E. Tereshina; G. Burkhanov; O. Chistyakov; R. Grechishkin; A. Salamova; V. Verbetsky

    2011-01-01

    The hydrogenation effect on the hysteresis properties of rapidly quenched (RQ) (Nd0.55Ho0.45)2.7(Fe0.8Co0.2)14B1.2 compound obtained by melt-spinning is studied. A comparative study of RQ alloy and its hydride (Nd0.55Ho0.45)2.7(Fe0.8Co0.2)14B1.2H2.5 has shown that hydrogenation resulted in the increase of magnetization without significant effect on the Curie temperature. In contrast to hydrogen-free alloy having a maximum on the Hc(T) curve, the Hc of

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  3. 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.

  4. 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.

  5. Dynamic hysteresis in cyclic deformation of crystalline solids.

    PubMed

    Laurson, Lasse; Alava, Mikko J

    2012-10-12

    The hysteresis or internal friction in the deformation of crystalline solids stressed cyclically is studied from the viewpoint of collective dislocation dynamics. Stress-controlled simulations of a dislocation dynamics model at various loading frequencies and amplitudes are performed to study the stress-strain rate hysteresis. The hysteresis loop areas exhibit a maximum at a characteristic frequency and a power law frequency dependence in the low frequency limit, with the power law exponent exhibiting two regimes, corresponding to the jammed and the yielding or moving phases of the system, respectively. The first of these phases of the system exhibits nontrivial critical-like viscoelastic dynamics, crossing over to intermittent viscoplastic deformation for higher stress amplitudes. PMID:23102332

  6. Hysteresis losses and magnetic phenomena in ribbons of type II superconductors in the noncollinear regime

    NASA Astrophysics Data System (ADS)

    LeBlanc, M. A. R.; Lorrain, J. P.

    1984-06-01

    We have measured hysteresis losses, W(h0, hb, Hb0), in ribbons of VTi and Nb subjected to oscillating magnetic fields of various amplitudes h0 directed transverse to a static bias magnetic field Hb0, hence the name, noncollinear regime. A second bias field hb along h0 may also be introduced. Hb0 and h0 are directed along the length and width of the ribbon respectively or vice versa (90° rotation). The families of data curves are compared with the predictions of double critical state models where (i) dB/dx=±FP(B)/B governs the critical gradients of the magnetic induction and (ii) d?/dx=±FP(B)F(?)/B2, the spatial variation of the orientation of the sheets of flux lines, with ?=0 along Hb0. The effect on W(h0,hb,Hb0) of choosing F(?)=1/tan ?, k and k/(1+???)2 is illustrated and the latter is seen to yield the best agreement. The locus of the magnetization along the length and width of the samples, and , have been monitored separately and simultaneously during the cycles of h0(t) for various h0 and Hb0 with hb=0 or h0. These observations, in particular the curves of the magnetization along Hb0, constitute severe tests of any model. The corresponding curves generated by the model using F(?)=k/(1+???)2 are presented. The physical origin of F(?) is explored.

  7. 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.

  8. 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.

  9. Domain Nucleation and Hysteresis Loop Shape in Piezoresponse Force Spectroscopy

    SciTech Connect

    Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Kalinin, Sergei V [ORNL

    2006-01-01

    Electromechanical hysteresis loop measurements in piezoresponse force microscopy (PFM) [piezoresponse force spectroscopy (PFS)] have emerged as a powerful technique for probing ferroelectric switching behavior on the nanoscale. Interpretation of PFS data requires the relationship between the domain parameters and PFM signal to be established. Here, the authors analyze the switching process using modified point charge model. The charge parameters are selected to reproduce tip-induced surface potential and tip radius of curvature. The relationship between geometric parameters of semiellipsoidal domain and PFM signal is derived using linear Green's function theory. The role of domain nucleation on hysteresis loop is established.

  10. Low hysteresis FeMn-based top spin valve.

    PubMed

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

    2012-09-01

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

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

    SciTech Connect

    Depla, D.; Haemers, J.; Buyle, G.; Gryse, R. de [Department of Solid State Sciences, Ghent University, Krijgslaan 281 (S1), B-9000 Ghent (Belgium)

    2006-07-15

    Rotating cylindrical magnetrons are used intensively on industrial scale. A rotating cylindrical magnetron on laboratory scale makes it possible to study this deposition technique in detail and under well controlled conditions. Therefore, a small scale rotating cylindrical magnetron was designed and used to study the influence of the rotation speed on the hysteresis behavior during reactive magnetron sputtering of aluminum in Ar/O{sub 2} in dc mode. This study reveals that the hysteresis shifts towards lower oxygen flows when the rotation speed of the target is increased, i.e., target poisoning occurs more readily when the rotation speed is increased. The shift is more pronounced for the lower branch of the hysteresis loop than for the upper branch of the hysteresis. This behavior can be understood qualitatively. The results also show that the oxidation mechanism inside the race track is different from the oxidation mechanism outside the race track. Indeed, outside the race track the oxidation mechanism is only defined by chemisorption while inside the race track reactive ion implantation will also influence the oxidation mechanism.

  12. 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 ...

  13. A Preisach Model for Quantifying Hysteresis in an Atomic Force Microscope

    E-print Network

    A Preisach Model for Quantifying Hysteresis in an Atomic Force Microscope Ralph C. Smith # , Murti Atomic force microscopes employ stacked or cylindrical piezoceramic actuators to achieve sub. Keywords: Atomic force microscope, hysteresis, constitutive nonlinearities, Preisach model 1. Introduction

  14. A Preisach Model for Quantifying Hysteresis in an Atomic Force Microscope

    E-print Network

    A Preisach Model for Quantifying Hysteresis in an Atomic Force Microscope Ralph C. Smith , Murti Atomic force microscopes employ stacked or cylindrical piezoceramic actuators to achieve sub in various control designs. Keywords: Atomic force microscope, hysteresis, constitutive nonlinearities

  15. Background Simulation Experiment Conclusion Hysteresis in the Nonlinear Tunnelling of Light

    E-print Network

    Petta, Jason

    Background Simulation Experiment Conclusion Hysteresis in the Nonlinear Tunnelling of Light Through of Light Through a Barrier #12;Background Simulation Experiment Conclusion Outline 1 Background Nonlinear Optics Hysteresis 2 Simulation Method Results 3 Experiment Images Analysis 4 Conclusion Stefan M

  16. A compensation method for the hysteresis error of DVD VCM

    Microsoft Academic Search

    Chih-Liang Chu; Kuang-Chao Fan; Ye-Jing Chen

    2004-01-01

    The present study considers an autofocusing laser probe system used for the measurement of the surface profile and roughness of an object. The system is based upon a modified pickup head of a commercially available DVD player which uses a voice coil motor (VCM) to drive an objective lens during the autofocusing process. It is known that hysteresis of the

  17. 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

  18. 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.

  19. 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.-

  20. Cavitation level-acoustic intensity hysteresis: experimental and numerical characterization

    E-print Network

    Boyer, Edmond

    Cavitation level-acoustic intensity hysteresis: experimental and numerical characterization P such as sonoporation, inertial cavitation is commonly considered as the main candidate inducing membrane poration. Thus, characterizing inertial cavitation, as related to bubble size distribution and medium history, is of great

  1. Combining Pattern Instability and Shape-Memory Hysteresis for Phononic

    E-print Network

    Combining Pattern Instability and Shape-Memory Hysteresis for Phononic Switching Ji-Hyun Jang Received April 10, 2009 ABSTRACT We report a fully reversible and robust shape-memory effect in a two simulations correctly capture the three steps of the shape-memory cycle observed experimentally. Structures

  2. 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

  3. 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...

  4. A Micromechanics-Based Hysteresis Model for Ferroelectric Ceramics

    Microsoft Academic Search

    J. Li; G. J. Weng

    2001-01-01

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

  5. The mechanism by which fish antifreeze proteins cause thermal hysteresis

    Microsoft Academic Search

    Erlend Kristiansen; Karl Erik Zachariassen

    2005-01-01

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

  6. Hysteresis and energy demand: the Announcement Effects and

    E-print Network

    Watson, Andrew

    -series regressions on quarterly and annual data 1973-2003 for UK energy demand by using sectors. The demands expect a price effect when the tax was actually imposed, reducing energy consumption, due to the negativeHysteresis and energy demand: the Announcement Effects and the effects of the UK Climate Change

  7. Instantaneous Feedback Controlled PWM Inverter with Adaptive Hysteresis

    Microsoft Academic Search

    Atsuo Kawamura; Richard Hoft

    1984-01-01

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

  8. Clockwise Hysteresis Loops in the Macroscopic Fundamental Diagram

    E-print Network

    California at Berkeley, University of

    Clockwise Hysteresis Loops in the Macroscopic Fundamental Diagram Vikash V. Gayah and Carlos F in the Macroscopic Fundamental Diagram WORKING PAPER Vikash V. Gayah and Carlos F. Daganzo UC Berkeley Center A recent study reported that the Macroscopic Fundamental Diagram of a medium size city exhibited

  9. Experimental Testing Of An Anisotropic Vector Hysteresis Model

    Microsoft Academic Search

    A. Bergqvist; A. Lundgren; G. Engdahl

    1997-01-01

    rolling direction (RD) and kTD in the transversal direction (TD) respectively. This leaves a total of four parameters related to hysteresis which were determined as follows: c was estimated from a small minor loop; then ~RD and U were adjusted to fit the measured alternating loss as a function of flux density amplitude in RD. Finally ~TD was adjusted to

  10. Hysteresis, Import Penetration, and Exchange Rate Pass-Through

    Microsoft Academic Search

    Avinash K Dixit

    1989-01-01

    A competitive industry has established home firms and foreign firms with entry and exit costs. The real exchange rate follows a Brownian motion. Industry equilibrium is determined using methods of option pricing. Entry requires the operating profit to exceed the interest on the entry cost, and similarly for exit. The middle band of rates without entry or exit yields hysteresis;

  11. 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

  12. Iterative compensation for hysteresis effects in positioning and tracking problems

    NASA Astrophysics Data System (ADS)

    Tseng, C.; Mayergoyz, I.; McAvoy, P.; Krafft, C.

    2008-04-01

    An iterative algorithm for hysteresis compensation in micropositioning applications is presented. It is demonstrated that this algorithm has a geometric rate of convergence. The results of the testing of this iterative algorithm in tracking problems related to magnetic recording are reported.

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

    Microsoft Academic Search

    E. Cardeffi; Romano Giannetti; Bernardo Tellini

    2005-01-01

    This paper deals with the characterization of dynamic loops shapes and losses in soft magnetic materials. An experimental and theoretical analysis has been done in order to describe static and dynamic hysteresis on soft ferrite cores. A parallelogram-loop-based hysteresis modeling is described and discussed. The possibility of the model to include vector hysteresis and the related properties are then discussed,

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

    Microsoft Academic Search

    Hani Vahedi; Abdolreza Sheikholeslami; Mohammad Tavakoli Bina

    2011-01-01

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

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

    E-print Network

    Weidner, John W.

    is changed. A common electro- chemical example of such a time-dependent hysteresis is cyclic vol- tammetry are stable, reproducible, and rate- independent. Such loops are termed permanent hysteresis,1-independent phenomenon. Hysteresis is well-studied in adsorption1 and magnetism,2 but there are only a few documented

  16. The marine biodiversity curve is an icon of paleobiology. The familiar curve shows

    E-print Network

    Waxman, David

    with Earth system events might be a geological snipe hunt. 1 Peters, S.E. and Foote, M. (2001) Biodiversity reopened the question. In a new paper, Peters and Foote [1] use the number of geological formations of geological formations. Similarly, global diversity was positively correlated with the proportion

  17. Droplets on inclined plates: local and global hysteresis of pinned capillary surfaces.

    PubMed

    Musterd, Michiel; van Steijn, Volkert; Kleijn, Chris R; Kreutzer, Michiel T

    2014-08-01

    Local contact line pinning prevents droplets from rearranging to minimal global energy, and models for droplets without pinning cannot predict their shape. We show that experiments are much better described by a theory, developed herein, that does account for the constrained contact line motion, using as an example droplets on tilted plates. We map out their shapes in suitable phase spaces. For 2D droplets, the critical point of maximum tilt depends on the hysteresis range and Bond number. In 3D, it also depends on the initial width, highlighting the importance of the deposition history. PMID:25148339

  18. 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.

  19. Droplets on Inclined Plates: Local and Global Hysteresis of Pinned Capillary Surfaces

    NASA Astrophysics Data System (ADS)

    Musterd, Michiel; van Steijn, Volkert; Kleijn, Chris R.; Kreutzer, Michiel T.

    2014-08-01

    Local contact line pinning prevents droplets from rearranging to minimal global energy, and models for droplets without pinning cannot predict their shape. We show that experiments are much better described by a theory, developed herein, that does account for the constrained contact line motion, using as an example droplets on tilted plates. We map out their shapes in suitable phase spaces. For 2D droplets, the critical point of maximum tilt depends on the hysteresis range and Bond number. In 3D, it also depends on the initial width, highlighting the importance of the deposition history.

  20. Cloning and characterization of a thermal hysteresis (antifreeze) protein with DNA-binding activity from winter bittersweet nightshade, Solanum dulcamara.

    PubMed

    Huang, Tao; Duman, John G

    2002-03-01

    The gene for a thermal hysteresis (antifreeze) protein (sthp-64) from the bittersweet nightshade, Solanum dulcamara, was cloned and characterized. An expression cDNA library prepared from November S. dulcamara was screened using a polyclonal antibody generated against a previously purified 67 kDa thermal hysteresis protein, and positive clones were identified and sequenced. The full-length thermal hysteresis protein gene was cloned into an Escherichia coli expression vector and expressed as a fusion protein. The putative thermal hysteresis protein (STHP-64) contains two conserved regions 56 and 57 amino acids in length which have the C-X4-C-X22-23-H-X1-H zinc finger motif which is present in WRKY proteins, a family of transcription factors which play a role in regulating expression of pathogenesis-related proteins in plants. Additional features of transcription factors, such as an acidic domain between the two zinc-fingers and a glutamine-rich region upstream of the first zinc-finger are also present in STHP-64. A DNA binding assay showed that the expressed STHP-64 fusion protein has specific DNA-binding ability. A unique feature of STHP-64 is that the C-terminus contains 10 consecutive 13-mer repeats. Such repeats are a common feature of animal antifreeze proteins. The expressed STHP-64 fusion protein had low levels of thermal hysteresis activity, but this activity was considerably increased by addition of citrate, which is known as an enhancer of certain insect antifreeze proteins. Northern blots demonstrated that the STHP-64 transcript was not present in leaves until November and December, suggesting that cold acclimation induces STHP-64 production. PMID:11905961

  1. 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.

  2. 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.

  3. 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

  4. ELLIPTIC CURVES OVER C MICHAEL TRAVIS

    E-print Network

    May, J. Peter

    ELLIPTIC CURVES OVER C MICHAEL TRAVIS Abstract. Elliptic curves are an exciting example of mathematics that is at the intersection of numerous fields of study. This paper begins by introducing elliptic to showing that complex tori are isomorphic to complex elliptic curves. I will take a mostly analytic

  5. 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.

  6. Utilizing dynamic tensiometry to quantify contact angle hysteresis and wetting state transitions on nonwetting surfaces.

    PubMed

    Kleingartner, Justin A; Srinivasan, Siddarth; Mabry, Joseph M; Cohen, Robert E; McKinley, Gareth H

    2013-11-01

    Goniometric techniques traditionally quantify two parameters, the advancing and receding contact angles, that are useful for characterizing the wetting properties of a solid surface; however, dynamic tensiometry, which measures changes in the net force on a surface during the repeated immersion and emersion of a solid into a probe liquid, can provide further insight into the wetting properties of a surface. We detail a framework for analyzing tensiometric results that allows for the determination of wetting hysteresis, wetting state transitions, and characteristic topographical length scales on textured, nonwetting surfaces, in addition to the more traditional measurement of apparent advancing and receding contact angles. Fluorodecyl POSS, a low-surface-energy material, was blended with commercially available poly(methyl methacrylate) (PMMA) and then dip- or spray-coated onto glass substrates. These surfaces were probed with a variety of liquids to illustrate the effects of probe liquid surface tension, solid surface chemistry, and surface texture on the apparent contact angles and wetting hysteresis of nonwetting surfaces. Woven meshes were then used as model structured substrates to add a second, larger length scale for the surface texture. When immersed into a probe liquid, these spray-coated mesh surfaces can form a metastable, solid-liquid-air interface on the largest length scale of surface texture. The increasing hydrostatic pressure associated with progressively greater immersion depths disrupts this metastable, composite interface and forces penetration of the probe liquid into the mesh structure. This transition is marked by a sudden change in the wetting hysteresis, which can be systematically probed using spray-coated, woven meshes of varying wire radius and spacing. We also show that dynamic tensiometry can accurately and quantitatively characterize topographical length scales that are present on microtextured surfaces. PMID:24070378

  7. 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.

  8. Metal phases in ordinary chondrites: Magnetic hysteresis properties and implications for thermal history

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Magnetic properties are sensitive proxies to characterize FeNi metal phases in meteorites. We present a data set of magnetic hysteresis properties of 91 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 that dominates the induced magnetism and tetrataenite (both in the cloudy zone as single-domain grains, and as larger multidomain grains in plessite and in the rim of zoned taenite) dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. The bulk metal contents derived from magnetic measurements are in agreement with those estimated previously from chemical analyses. We evidence a decreasing metal content with increasing petrologic type in ordinary chondrites, compatible with oxidation of metal during thermal metamorphism. Types 5 and 6 ordinary chondrites have higher tetrataenite content than type 4 chondrites. This is compatible with lower cooling rates in the 650-450 °C interval for higher petrographic types (consistent with an onion-shell model), but is more likely the result of the oxidation of ordinary chondrites with increasing metamorphism. In equilibrated chondrites, shock-related transient heating events above approximately 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 (e.g., following shock reheating or excavation after thermal metamorphism). Our data strengthen the view that the poor magnetic recording properties of multidomain kamacite and the secondary origin of tetrataenite make equilibrated ordinary chondrites challenging targets for paleomagnetic study.

  9. Hysteresis measurements of remanent polarization and coercive field in polymers

    NASA Astrophysics Data System (ADS)

    Dickens, B.; Balizer, E.; DeReggi, A. S.; Roth, S. C.

    1992-11-01

    An experimental method is described which allows estimation of remanent polarization and coercive field without assuming functional forms for the capacitive and electrical resistance terms. The method can be used to measure polarization in specimens with voltage-dependent conductivity (often arising from the presence of ions in the specimens), voltage-dependent capacitance, and significant amounts of space charge. It consists of: (1) performing bipolar current/voltage hysteresis loops to allow a steady state of remanent polarization and space charge to build up in the specimen, and (2) following a bipolar loop with two or more unipolar loops in which the polarization changes in the first unipolar loop. Both sinusoidal and linear time-dependent applied voltages may be used. Automatic data processing of hysteresis loops is described for cases in which specimen behavior may be considered to be ideal.

  10. 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.

  11. 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

  12. Hysteresis in one-dimensional reaction-diffusion systems.

    PubMed

    Rákos, A; Paessens, M; Schütz, G M

    2003-12-01

    We introduce a simple nonequilibrium model for a driven diffusive system with nonconservative reaction kinetics in one dimension. The steady state exhibits a phase with broken ergodicity and hysteresis which has no analog in systems investigated previously. We identify the main dynamical mode, viz., the random motion of a shock in an effective potential, which provides a unified framework for understanding phase coexistence as well as ergodicity breaking. This picture also leads to the exact phase diagram of the system. PMID:14683218

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

    SciTech Connect

    Vengrinovich, Valeriy, E-mail: veng@iaph.bas-net.by [Institute of Applied Physics of the Belarus Academy of Sciences 220072, Akademicheskaya street 16, Minsk (Belarus)

    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. Element specific separation of bulk and interfacial magnetic hysteresis loops

    Microsoft Academic Search

    A. K. Suszka; C. J. Kinane; C. H. Marrows; B. J. Hickey; D. A. Arena; J. Dvorak; A. Lamperti; B. K. Tanner; S. Langridge

    2007-01-01

    We have studied the reversal of the bulk and interfacial magnetizations of the free layer of a spin valve using soft x-ray resonant magnetic scattering. By dusting the interface of the NiFe free layer with a few angströms of Co, we were able to distinguish between the interfacial and bulk magnetisms by tuning the x-ray photon energy. We measured hysteresis

  15. Effect of Tension Upon Magnetization and Magnetic Hysteresis in Permalloy

    Microsoft Academic Search

    O. E. Buckley; L. W. McKeehan

    1925-01-01

    Magnetic properties of permalloy.-Effect of tension on magnetization and hysteresis. Wires of 5 nickel-iron alloys containing 45, 65, 78.5, 81 and 84 percent Ni, 60 cm long and 0.1 cm in diameter, were studied by a ballistic method, for tensions up to 10,000 lb per in.2 and fields up to saturation (10 to 20 gauss). Permalloy with 81 percent Ni

  16. Negative resistance and anomalous hysteresis in a collective molecular motor

    PubMed

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

    2000-06-01

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

  17. Influence of hysteresis loop shape on the nonlinear dynamics of shape memory alloy oscillator excited by non-ideal energy sources

    NASA Astrophysics Data System (ADS)

    Piccirillo, V.; Tusset, A. M.; Balthazar, J. M.; Bernardini, D.; Rega, G.

    2014-12-01

    The dynamical response of systems with shape memory alloy (SMA) presents a different behavior due to their nonlinear characteristic. SMA nonlinear response is associated with adaptive dissipation related to their hysteretic behavior. This paper discusses the nonlinear responses of shape-memory non-ideal oscillators, based on a thermomechanical consistent model with four state variables. Two cases are investigating, namely, the case when SMA presents a large hysteresis loop and another one with less hysteresis. Computer simulations are carried out via a numerical approach showing qualitative results concerned with regular and non-regular motions.

  18. Hysteresis Behaviour and Specific Damping Capacity of Negative Poisson's Ratio Foams Martz, E. O., Lakes, R. S., and Park, J. B. "Hysteresis behaviour and specific damping capacity of

    E-print Network

    Lakes, Roderic

    1 Hysteresis Behaviour and Specific Damping Capacity of Negative Poisson's Ratio Foams Martz, E. O., Lakes, R. S., and Park, J. B. "Hysteresis behaviour and specific damping capacity of negative Poisson exhibiting a negative Poisson's ratio(1). Untransformed control and transformed negative Poisson's ratio

  19. Understanding curved detonation waves

    SciTech Connect

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

    1992-01-01

    A wave curve is the set of final states to which an initial state may be connected by a traveling wave. In gas dynamics, for example, the wave curve consists of the shock Hugoniot curve for compressive waves and the rarefaction curve for expansive waves. In this paper, we discuss the wave curve for an undriven planar detonation and for general planar detonations. We then extend the wave curve concept to detonations in converging and diverging geometry. We also discuss the application of these wave curves to the numerical computation of detonation problems.

  20. Understanding curved detonation waves

    SciTech Connect

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

    1992-10-01

    A wave curve is the set of final states to which an initial state may be connected by a traveling wave. In gas dynamics, for example, the wave curve consists of the shock Hugoniot curve for compressive waves and the rarefaction curve for expansive waves. In this paper, we discuss the wave curve for an undriven planar detonation and for general planar detonations. We then extend the wave curve concept to detonations in converging and diverging geometry. We also discuss the application of these wave curves to the numerical computation of detonation problems.

  1. 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: yhkim76@skku.edu, E-mail: skpark@cau.ac.kr [School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Kim, Yong-Hoon, E-mail: yhkim76@skku.edu, E-mail: skpark@cau.ac.kr [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    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.

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

    NASA Astrophysics Data System (ADS)

    Jo, Jeong-Wan; Kim, Yong-Hoon; Park, Sung Kyu

    2014-07-01

    In this report, photo-induced hysteresis, threshold voltage (VT) 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 VT 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 VT 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 VT shift in photochemically activated TFTs.

  3. 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.

  4. Melting curves and entropy of melting of iron under Earth's core conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Jin; Liu, Zhi-Yong; Liu, Zhong-Li; Cai, Ling-Cang

    2015-07-01

    The melting curves of iron are determined up to 365 GPa via molecular dynamic (MD) simulations combining with the embedded atom model (EAM) potential developed by Ackland et al. We simulated the melting with three approaches, the hysteresis, two-phase and recently modified Z methods. All three techniques can produce satisfying results, consistent well with most of static compression measurements and shock experiments. Hence, we recommend that these three techniques and this EAM potential are reliable techniques and potential for simulating melting properties of iron. Fitting the well-known Simon equation to our two-phase data we yield the analytical melting curve for iron: 1825(1 + P/57.723)0.654, which gives a melting point at the inner core boundary of 6345 K, very close to the recent diamond anvil cell (DAC) extrapolated value and other ab initio calculations. Furthermore, the analyses of our entropy of melting and solid-liquid interfacial energy ?sl indicate that at high pressure, the entropy of fusion shows weak pressure effect. The ?sl increases monotonically with pressure, and can be described as a second-order polynomial relation.

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

    PubMed

    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

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

    PubMed

    Koštál, Vladimír; Renault, David; Rozsypal, Jan

    2011-10-01

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

  7. Modeling the effects of nanosized precipitates on magnetic hysteresis and Barkhausen effect signal

    NASA Astrophysics Data System (ADS)

    Lo, C. C. H.

    2012-04-01

    A model has been developed for describing the effects of randomly distributed precipitates on magnetic hysteresis and Barkhausen emissions based on a hysteretic-stochastic process model of domain wall dynamics. The pinning of magnetic domain walls by spherical precipitates is described in terms of the pinning strength, which is proportional to the number density and cross-sectional area of the precipitates, and of the interaction range, which depends on the particle spacing and grain size. The model was used to simulate hysteresis loops and Barkhausen effect signals of a series of thermally aged FeCu samples with different number densities and sizes of Cu-rich precipitates. The linear dependence of the coercivity on the sample hardness was reproduced in the simulations. The rms values and pulse height distributions of the measured and modeled Barkhausen signals show similar dependence on the aging time, which can be interpreted by considering the effects of varying the precipitate size and spacing on the strength and interaction range of domain wall pinning.

  8. N=1 Curve

    E-print Network

    Dan Xie

    2014-09-29

    N=1 curve is defined for four dimensional class S theory using Cayley-Hamilton theorem for two commuting matrices. The curve consists of three ingredients: 1: A set of N+1 degree N equations defining a curve; 2: a set of constraints relating the coefficients in the curve; 3: a canonically defined differential. We then extract from spectral curve various physical information such as the space of moduli fields, chiral ring relations, full moduli space, etc. Many examples are discussed, and the curve recovers the intricate vacua structure which often involves highly non-trivial field theory dynamics such as monopole condensation, dynamical generated superpotential, Seiberg duality, etc.

  9. Field-Driven Hysteresis of the d=3 Ising Spin Glass: Hard-Spin Mean-Field Theory

    NASA Astrophysics Data System (ADS)

    Yücesoy, Burcu; Berker, A. Nihat

    2008-03-01

    Hysteresis loops are obtained in the Ising spin-glass phase in d=3, using frustration-conserving hard-spin mean-field theory.[1] The system is driven by a time-dependent random magnetic field HQ that is conjugate to the spin-glass order Q, yielding a field-driven first-order phase transition through the spin-glass phase. The hysteresis loop area A of the Q-HQ curve scales with respect to the sweep rate h of magnetic field as A-A0 ˜ h^b. In the spin-glass and random-bond ferromagnetic phases, the sweep-rate scaling exponent b changes with temperature T, but appears not to change with antiferromagnetic bond concentration p. By contrast, in the pure ferromagnetic phase, b does not depend on T and has a sharply different value than in the two other phases. [1] B. Yücesoy and A.N. Berker, Phys. Rev. B 76, 014417 (2007).

  10. 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.

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

    Microsoft Academic Search

    Y. Zhai; L. Vu-Quoc

    2005-01-01

    We present a new systematic methodology to efficiently solve coupled electromagnetic problems with nonlinear hysteresis at low frequency (10 kHz), called static hysteresis, by the finite-element method. The methodology integrates a new domain-wall-motion hysteresis model for power magnetic components (POMACs) into a finite-element potential formulation via an implicit-inverse model calculation. It uses a novel two-level iterative algorithm incorporating the efficient

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

    Microsoft Academic Search

    Y. Zhai; L. Vu-Quoc

    2007-01-01

    We applied the proper orthogonal decomposition (POD) method to extract reduced-order models to efficiently solve nonlinear electromagnetic problems governed by Maxwell's equations with nonlinear hysteresis at low frequency (10 kHz), called static hysteresis, discretized by a finite-element method. We used a new domain-wall-motion hysteresis model for Power MAgnetic Components (POMACs) in the finite-element potential formulation via an efficient implicit-inverse model

  13. Hysteresis Nonlinearity Identification Using New Preisach Model-Based Artificial Neural Network Approach

    Microsoft Academic Search

    Mohammad Reza Zakerzadeh; Mohsen Firouzi; Hassan Sayyaadi; Saeed Bagheri Shouraki

    2011-01-01

    Preisach model is a well-known hysteresis identification method in which the\\u000ahysteresis is modeled by linear combination of hysteresis operators. Although\\u000aPreisach model describes the main features of system with hysteresis behavior,\\u000adue to its rigorous numerical nature, it is not convenient to use in real-time\\u000acontrol applications. Here a novel neural network approach based on the Preisach\\u000amodel is

  14. 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.

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

    Microsoft Academic Search

    S. A. Kulinich; M. Farzaneh

    2009-01-01

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

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

    SciTech Connect

    Kim, Yunseok [ORNL; Yang, J.-C. [University of California, Berkeley; Chu, Ying Hao [National Chiao Tung University, Hsinchu, Taiwan; Yu, Pu [University of California, Berkeley; Lu, X. [Xidian University, China; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

    2012-01-01

    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.

  17. Strain Hysteresis During Thermoelastic Martensitic Transformations in Titanium Nickelide Upon Mechanical Loading

    NASA Astrophysics Data System (ADS)

    Plotnikov, V. A.; Moreva, M. V.

    2015-05-01

    The strain hysteresis is a consequence of energy dissipation during martensitic transformations in titanium nickelide upon mechanical loading. The main reasons for the hysteresis are the processes of entropy production in the transformation cycle during heat liberation and absorption. On an example of TN-1V and Ti50Ni40Cu10 alloys, the influence of accumulation of crystallographic defects on the evolution of the hysteresis loop is demonstrated during multiple martensitic transformation cycling.

  18. Improving Handoff Performance by Using Distance-Based Dynamic Hysteresis Value

    Microsoft Academic Search

    Huamin Zhu; Kyungsup Kwak

    2006-01-01

    In this study, an adaptive handoff algorithm with a dynamic hysteresis value, based on the distance between the mobile station\\u000a and the serving base station, is proposed for cellular communications. Handoff probability is calculated to evaluate handoff\\u000a algorithms analytically. The proposed handoff algorithm is compared with an algorithm with fixed hysteresis, an algorithm\\u000a using both threshold and hysteresis, and a

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

    SciTech Connect

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

    2012-01-01

    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.

  20. 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.

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

    SciTech Connect

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

    1991-08-22

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

  2. Flicker Curves of Different Types of Lamps

    Microsoft Academic Search

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

    2006-01-01

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

  3. Utilizing dynamic tensiometry to quantify contact angle hysteresis and wetting state transitions on

    E-print Network

    on nonwetting surfaces Justin A. Kleingartner, Siddarth Srinivasan, Joseph M. Mabry, Robert E. Cohen, Contact angle hysteresis, Hierarchical structures, Superhydrophobic surfaces, Superoleophobic surfaces

  4. Autumn shows roundup

    Microsoft Academic Search

    Richard Bloss

    2002-01-01

    A report on three major American automation shows where innovative products and automated assembly technologies formed a focus. Products reviewed include grippers, actuators, assembly modules, dispensing controller and pneumatic components from a number of suppliers.

  5. Matrix-free synthesis of spin crossover micro-rods showing a large hysteresis loop centered at room temperature.

    PubMed

    Peng, Haonan; Molnár, Gábor; Salmon, Lionel; Bousseksou, Azzedine

    2015-05-21

    An original simple homogeneous acid medium was used to synthesize polymer/surfactant-free acicular micro-rod particles (10-40 ?m long by 0.1-0.3 ?m diameter) of the novel [Fe(Htrz)3](CF3SO3)2 complex. The study of the spin crossover properties reveals a rare 50 K hysteretic behavior perfectly centered at room temperature accompanied by a pronounced thermochromism effect, purple in the low spin state and white in the high spin state. PMID:25959768

  6. Ionically-mediated electromechanical hysteresis in transition metal oxides

    SciTech Connect

    Kim, Yunseok [ORNL] [ORNL; Kumar, Amit [ORNL] [ORNL; Jesse, Stephen [ORNL] [ORNL; Kalinin, Sergei V [ORNL] [ORNL

    2012-01-01

    Electromechanical activity, remanent polarization states, and hysteresis loops in paraelectric TiO2 and SrTiO3 are observed. The coupling between the ionic dynamics and incipient ferroelectricity in these materials is analyzed using extended Ginsburg Landau Devonshire (GLD) theory. The possible origins of electromechanical coupling including ionic dynamics, surface-charge induced electrostriction, and ionically-induced ferroelectricity are identified. For the latter, the ionic contribution can change the sign of first order GLD expansion coefficient, rendering material effectively ferroelectric. These studies provide possible explanation for ferroelectric-like behavior in centrosymmetric transition metal oxides.

  7. 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.

  8. 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.

  9. Minor hysteresis loops measurements for characterization of cast iron

    NASA Astrophysics Data System (ADS)

    Vértesy, G.; Uchimoto, T.; Takagi, T.; Tomáš, I.; Stupakov, O.; Mészáros, I.; Pávó, J.

    2006-02-01

    Structural variation in a series of cast iron samples was non-destructively characterized by means of sets of magnetic minor hysteresis loops. The flat samples were magnetized by an attached yoke, and reliable parameters were obtained from the series of minor loops, without magnetic saturation of the samples. It was found, that some magnetic quantities, well known to be closely connected to the samples’ structure variation, especially relative coercivity and remanent induction, could be distinguished more sensitively from minor loops, than from the major one.

  10. Titania nanorods curve to lower their energy.

    PubMed

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

    2013-08-01

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

  11. An extraordinary origami curve

    Microsoft Academic Search

    Frank Herrlich; Gabriela Schmithusen

    2008-01-01

    We study a special Teichmueller curve in the moduli space of curves of genus\\u000a3 that is intersected by infinitely many other Teichmueller curves. The Veech\\u000agroup of the underlying translation surface is SL_2(Z). All occurring\\u000aTeichmueller curves are induced by origamis, i.e. unramified coverings of the\\u000aonce punctured torus.

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

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

    PubMed

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

    2006-05-28

    Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs), collectively abbreviated as AF(G)Ps, are synthesized by various organisms to enable their cells to survive in subzero environments. Although the AF(G)Ps are markedly diverse in structure, they all function by adsorbing to the surface of embryonic ice crystals to inhibit their growth. This adsorption results in a freezing temperature depression without an appreciable change in the melting temperature. The difference between the melting and freezing temperatures, termed thermal hysteresis (TH), is used to detect and quantify the antifreeze activity. Insights from crystallographic structures of a number of AFPs have led to a good understanding of the ice-protein interaction features. Computational studies have focused either on verifying a specific model of AFP-ice interaction or on understanding the protein-induced changes in the ice crystal morphology. In order to explain the origin of TH, we propose a novel two-dimensional adsorption kinetic model between AFPs and ice crystal surfaces. The validity of the model has been demonstrated by reproducing the TH curve on two different beta-helical AFPs upon increasing the protein concentration. In particular, this model is able to accommodate the change in the TH behavior observed experimentally when the size of the AFPs is increased systematically. Our results suggest that in addition to the specificity of the AFPs for the ice, the coverage of the AFPs on the ice surface is an equally necessary condition for their TH activity. PMID:16774359

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

    NSDL National Science Digital Library

    Arup K. Chakraborty (Massachusetts Institute of Technology; Department of Chemical Engineering; REV)

    2009-04-14

    Activation of Ras proteins underlies functional decisions in diverse cell types. Two molecules, Ras-GRP and SOS (Ras–guanine nucleotide–releasing protein and Son of Sevenless, respectively), catalyze Ras activation in lymphocytes. Binding of active Ras to the allosteric pocket of SOS markedly increases the activity of SOS. Thus, there is a positive feedback loop regulating SOS. Combining in silico and in vitro studies, we demonstrate that “digital” signaling in lymphocytes (cells are “on” or “off”) is predicated on this allosteric regulation of SOS. The SOS feedback loop leads to hysteresis in the dose-response curve, which may enable T cells to exhibit “memory” of past encounters with antigen. Ras activation by Ras-GRP alone is “analog” (a graded increase in activation in response to an increase in the amplitude of the stimulus). We describe how the complementary analog (Ras-GRP) and digital (SOS) pathways act on Ras to efficiently convert analog input to digital output and make predictions regarding the importance of digital signaling in lymphocyte function and development.

  15. Isothermal magnetisation curves measured with a coercivity spectrometer

    NASA Astrophysics Data System (ADS)

    Spassov, S.; Nurgaliev, D. K.; Heller, F.; Egli, R.; Jasonov, P. G.

    2009-04-01

    The coercivity spectrometer constructed at Kazan University consists mainly of a rotating non-magnetic disk spinning with a frequency of 22 Hz which passes the sample to be measured through two induction coils during each turn. One coil is placed on the pole tips of an electromagnet to measure induced magnetisation, while remanence is measured a three-fourth turn later in a second -metal shielded induction coil. After completing a full turn, the next field step is applied. Having reaching maximum values, the field strength is reduced to zero and then incremented in the opposite direction up to the maximum. Finally, high field remanence stability is monitored for about 100 s. High resolution curves of initial magnetisation, descending hysteresis branch, isothermal remanent magnetisation acquisition, backfield remanence and short-term remanence decay can be expeditiously measured. The coercivity spectrometer provides standard hysteresis parameters such as coercive force, coercivity of remanence, saturation magnetisation, saturation remanence and magnetic high-field susceptibility. The advantage over other hysteresis measuring devices such as for instance vibrating sample and alternating gradient field magnetometers or variable field translation balances is besides short-measurement time and low price, the high measurement resolution allowing more sophisticated data interpretation like coercivity spectra analysis. The other advantage is the instantaneous measurement of induced and remanent magnetisation which can be used for separation of transient and remanent magnetisation contributions and the study of magnetostatic interactions applying the principles of the Preisach-Néel theory. We will present measurement results of artificial (e.g. ferrofluid, magnetic tape) and natural (e.g. Tiva Canyon tuff, lavas, baked clay) samples and interpret and discuss them in terms of the Preisach-Néel theory (cf. Fabian & von Dobeneck 1997) demonstrating the great potential of the coercivity spectrometer for environmental magnetic investigations. Fabian, K. & von Dobeneck, T. 1997. Isothermal magnetization of samples with stable Preisach functions: A survey of hysteresis, remanence and rock magnetic parameters, Journal of Geophysical Research, 102, 17659 - 17677.

  16. Do Elephants Show Empathy?

    Microsoft Academic Search

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

    2008-01-01

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

  17. 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…

  18. Demonstration Road Show

    NSDL National Science Digital Library

    2009-04-06

    The Idaho State University Department of Physics conducts science demonstration shows at S. E. Idaho schools. Four different presentations are currently available; "Forces and Motion", "States of Matter", "Electricity and Magnetism", and "Sound and Waves". Information provided includes descriptions of the material and links to other resources.

  19. Earthquake Damage Slide Show

    NSDL National Science Digital Library

    This slide show presents examples of various types of damage caused by earthquakes. Photos include structural failures in bridges and buildings, landshifts, landslides, liquefaction, fires, tsunamis, and human impacts. Supplemental notes are provided to aid instructors about the photos presented on each slide.

  20. Honored Teacher Shows Commitment.

    ERIC Educational Resources Information Center

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  1. What Do Maps Show?

    ERIC Educational Resources Information Center

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

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

  2. From principal curves to granular principal curves.

    PubMed

    Zhang, Hongyun; Pedrycz, Witold; Miao, Duoqian; Wei, Zhihua

    2014-06-01

    Principal curves arising as an essential construct in dimensionality reduction and data analysis have recently attracted much attention from theoretical as well as practical perspective. In many real-world situations, however, the efficiency of existing principal curves algorithms is often arguable, in particular when dealing with massive data owing to the associated high computational complexity. A certain drawback of these constructs stems from the fact that in several applications principal curves cannot fully capture some essential problem-oriented facets of the data dealing with width, aspect ratio, width change, etc. Information granulation is a powerful tool supporting processing and interpreting massive data. In this paper, invoking the underlying ideas of information granulation, we propose a granular principal curves approach, regarded as an extension of principal curves algorithms, to improve efficiency and achieve a sound accuracy-efficiency tradeoff. First, large amounts of numerical data are granulated into C intervals-information granules developed with the use of fuzzy C-means clustering and the two criteria of information granulation, which significantly reduce the amount of data to be processed at the later phase of the overall design. Granular principal curves are then constructed by determining the upper and the lower bounds of the interval data. Finally, we develop an objective function using the criteria of information confidence and specificity to evaluate the granular output formed by the principal curves. We also optimize the granular principal curves by adjusting the level of information granularity (the number of clusters), which is realized with the aid of the particle swarm optimization. A number of numeric studies completed for synthetic and real-world datasets provide a useful quantifiable insight into the effectiveness of the proposed algorithm. PMID:23996588

  3. Show-Me Center

    NSDL National Science Digital Library

    The Show-Me Center is a partnership of four NSF-sponsored middle grades mathematics curriculum development Satellite Centers (University of Wisconsin, Michigan State University, University of Montana, and the Educational Development Center). The group's website provides "information and resources needed to support selection and implementation of standards-based middle grades mathematics curricula." The Video Showcase includes segments on Number, Algebra, Geometry, Measure, and Data Analysis, with information on ways to obtain the complete video set. The Curricula Showcase provides general information, unit goals, sample lessons and teacher pages spanning four projects: the Connected Mathematics Project (CMP), Mathematics in Context (MiC), MathScape: Seeing and Thinking Mathematically, and Middle Grades Math Thematics. The website also posts Show-Me Center newsletters, information on upcoming conferences and workshops, and links to resources including published articles and unpublished commentary on mathematics school reform.

  4. The Truman Show

    Microsoft Academic Search

    Rolf F. Nohr

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

  5. Contact-angle hysteresis on super-hydrophobic surfaces.

    PubMed

    McHale, G; Shirtcliffe, N J; Newton, M I

    2004-11-01

    The relationship between perturbations to contact angles on a rough or textured surface and the super-hydrophobic enhancement of the equilibrium contact angle is discussed theoretically. Two models are considered. In the first (Wenzel) case, the super-hydrophobic surface has a very high contact angle and the droplet completely contacts the surface upon which it rests. In the second (Cassie-Baxter) case, the super-hydrophobic surface has a very high contact angle, but the droplet bridges across surface protrusions. The theoretical treatment emphasizes the concept of contact-angle amplification or attenuation and distinguishes between the increases in contact angles due to roughening or texturing surfaces and perturbations to the resulting contact angles. The theory is applied to predicting contact-angle hysteresis on rough surfaces from the hysteresis observable on smooth surfaces and is therefore relevant to predicting roll-off angles for droplets on tilted surfaces. The theory quantitatively predicts a "sticky" surface for Wenzel-type surfaces and a "slippy" surface for Cassie-Baxter-type surfaces. PMID:15518506

  6. Hysteresis of soft joints embedded with fluid-filled microchannels

    PubMed Central

    Ghatak, Animangsu; Majumder, Abhijit; Kumar, Rajendra

    2008-01-01

    Many arthropods are known to achieve dynamic stability during rapid locomotion on rough terrains despite the absence of an elaborate nervous system. While muscle viscoelasticity and its inherent friction have been thought to cause this passive absorption of energy, the role of embedded microstructures in muscles and muscle joints has not yet been investigated. Inspired by the soft and flexible hinge joints present in many of these animals, we have carried out displacement-controlled bending of thin elastic slabs embedded with fluid-filled microchannels. During loading, the slab bends uniformly to a critical curvature, beyond which the skin covering the channel buckles with a catastrophic decrease in load. In the reverse cycle, the buckled skin straightens out but at a significantly lower load. In such a loading–unloading cycle, this localized buckling phenomenon results in a dynamic change in the geometry of the joint, which leads to a significant hysteresis in elastic energy. The hysteresis varies nonlinearly with channel diameters and thicknesses of the slab, which is captured by a simple scaling analysis of the phenomenon. PMID:18611846

  7. Contact angle hysteresis and pinning at periodic defects in statics.

    PubMed

    Iliev, Stanimir; Pesheva, Nina; Nikolayev, Vadim S

    2014-07-01

    This article deals with the theoretical prediction of the wetting hysteresis on nonideal solid surfaces in terms of the surface heterogeneity parameters. The spatially periodical chemical heterogeneity is considered. We propose precise definitions for both the advancing and the receding contact angles for the Wilhelmy plate geometry. It is well known that in such a system, a multitude of metastable states of the liquid meniscus occurs for each different relative position of the defect pattern on the plate with respect to the liquid level. As usual, the static advancing and receding angles are assumed to be a consequence of the preceding contact line motion in the respective direction. It is shown how to select the appropriate states among all metastable states. Their selection is discussed. The proposed definitions are applicable to both the static and the dynamic contact angles on heterogeneous surfaces. The static advancing and receding angles are calculated for two examples of periodic heterogeneity patterns with sharp borders: the horizontal alternating stripes of a different wettability (studied analytically) and the doubly periodic pattern of circular defects on a homogeneous base (studied numerically). The wetting hysteresis is determined as a function of the defect density and the spatial period. A comparison with the existing results is carried out. PMID:25122314

  8. 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)].

  9. Double rational normal curves with linear syzygies

    Microsoft Academic Search

    Nicolae Manolache

    2001-01-01

    :   In this note we are looking after nilpotent projective curves without embedded points, which have rational normal curves\\u000a of degree d as support, are defined (scheme-theoretically) by quadratic equations, have degree 2d and have only linear syzygies. We show that, as expected, no such curve does exist in ?\\u000a \\u000a d\\u000a \\u000a , and then consider doublings in a bigger ambient

  10. 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

  11. Magnetic Biasing of a Ferroelectric Hysteresis Loop in a Multiferroic Orthoferrite

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  12. Spatial Frequency Integration During Active Perception: Perceptual Hysteresis When an Object Recedes

    PubMed Central

    Brady, Timothy F.; Oliva, Aude

    2012-01-01

    As we move through the world, information about objects moves to different spatial frequencies. How the visual system successfully integrates information across these changes to form a coherent percept is thus an important open question. Here we investigate such integration using hybrid faces, which contain different images in low and high spatial frequencies. Observers judged how similar a hybrid was to each of its component images while walking toward or away from it or having the stimulus moved toward or away from them. We find that when the stimulus is approaching, observers act as if they are integrating across spatial frequency separately at each moment. However, when the stimulus is receding, observers show a perceptual hysteresis effect, holding on to details that are imperceptible in a static stimulus condition. Thus, observers appear to make optimal inferences by sticking with their previous interpretation when losing information but constantly reinterpreting their input when gaining new information. PMID:23162509

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

    PubMed

    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 cm(2) active area create a serpentine flow-field on an active area of 100 cm(2) 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

  14. 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

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  17. Gelfond-Bezier Curves

    E-print Network

    Ait-Haddou, Rachid; Nomura, Taishin

    2011-01-01

    We show that the generalized Bernstein bases in Muntz spaces defined by Hirschman and Widder [7] and extended by Gelfond [6] can be obtained as limits of the Chebyshev-Bernstein bases in Muntz spaces with respect to an interval [a,1] as the real number, a, converges to zero. Such a realization allows for concepts of curve design such as de Casteljau algorithm, blossom, dimension elevation to be translated from the general theory of Chebyshev blossom in Muntz spaces to these generalized Bernstein bases that we termed here as Gelfond-Bernstein bases. The advantage of working with Gelfond-Bernstein bases lies in the simplicity of the obtained concepts and algorithms as compared to their Chebyshev-Bernstein bases counterparts.

  18. Phase nucleation in curved space

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; García, Nicolás A.; Vitelli, Vincenzo; Lorenzana, José; Vega, Daniel A.

    2015-04-01

    Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature.

  19. Magnetic hysteresis properties and rotational hysteresis losses of synthetic stress-controlled titanomagnetite (Fe_2.4Ti_0.6O_4) particles-II. Rotational hysteresis losses

    NASA Astrophysics Data System (ADS)

    Keller, R.; Schmidbauer, E.

    1999-08-01

    Rotational hysteresis losses W_RH of a ferro- or ferrimagnet (determined by torque measurements) give information on anisotropies related to irreversible magnetization processes. We measured W_RH as a function of magnetic field H for milled and etched synthetic titanomagnetite Fe_2.4Ti_0.6O_4 particles of 2.4, 12.5 and 165 ?m grain size, which are assumed to show stress-controlled magnetic properties, between room temperature and the Curie point. For uniaxial single-domain (SD) particles, typical parameters that can be determined are in the low-field range a critical field for the onset of W_RH, a peak W_RH and a further typical field in the high-field region where W_RH tends to zero; all these parameters are associated with the anisotropy constant. For 2.4 ?m particles, assumed to be SD, the large experimental W_RH at all fields in the whole temperature range is ascribed predominantly to the action of high internal microstresses arising from a large density of dislocations and other lattice defects introduced by the milling process. The reduced magnitude of W_RH for pseudo-single-domain 12.5 ?m particles and the still smaller W_RH for multidomain (MD) 165 ?m particles is thought to be in the first place the result of much lower defect densities in conjunction with irreversible domain rotations. For each particle size, a rise of some W_RH parameters is observed for temperatures >120 degC, which coincides for MD 165 ?m particles with an increase of magnetic hysteresis parameters. The non-zero W_RH at the maximum applied field of H=1200 kA m^-1~15 kOe for all particles in the whole temperature region analysed is attributed to some kind of exchange anisotropy, caused by centres or areas in a particle related to a very high anisotropy, due probably to Fe^2+ in the neighbourhood of lattice defects.

  20. Moment-Rotation Hysteresis Behavior of Top and Seat Angle Steel Frame Connections

    Microsoft Academic Search

    Anant R. Kukreti; Ali S. Abolmaali

    1999-01-01

    This paper presents an approach toward formulating analytical models to predict the moment- rotation hysteresis behavior of top and seat angle connections. Experimental results obtained from 12 top and seat angle connection specimens are used to obtain the prediction equations for the parameters defining the moment rotation hysteresis loops of a typical top and seat angle connection. These parameters include

  1. 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.

  2. Linear parameter-varying control of hysteresis for active microgravity isolation

    Microsoft Academic Search

    R. S. Chandra; I. J. Fialho

    2002-01-01

    This work considers the use of linear parameter-varying methods to control a vibration isolation system with stiffness hysteresis. From a linear parameter-varying design perspective hysteresis is modeled as a stiffness parameter that takes values in a compact convex set with vertices determined from displacement constraints that exist in the system. The resulting controller consists of two vertex controllers along with

  3. Hysteresis, Avalanches, and Noise Matthew C. Kuntz, Olga Perkovi'c, Karin A. Dahmen,

    E-print Network

    Sethna, James P.

    Hysteresis, Avalanches, and Noise Matthew C. Kuntz, Olga Perkovi'c, Karin A. Dahmen, Bruce W simulations. In our studies of hysteresis and avalanches in a sim­ ple model of magnetism (the random be triggered when one of its neighbors flips (by participating in an avalanche), or a spin can be triggered

  4. cond-mat/9809122v223Apr1999 Hysteresis, Avalanches, and Noise

    E-print Network

    Sethna, James P.

    cond-mat/9809122v223Apr1999 Hysteresis, Avalanches, and Noise Matthew C. Kuntz, Olga Perkovi becomes crucial for larger simulations. In our studies of hysteresis and avalanches in a sim- ple model participating in an avalanche), or a spin can be triggered because of an increase in the external field H

  5. Random-field Potts model with dipolarlike interactions: Hysteresis, avalanches, and microstructure

    Microsoft Academic Search

    Benedetta Cerruti; Eduard Vives

    2008-01-01

    A model for the study of hysteresis and avalanches in a first-order phase transition from a single variant phase to a multivariant phase is presented. The model is based on a modification of the random-field Potts model with metastable dynamics by adding a dipolar interaction term truncated at nearest neighbors. We focus our study on hysteresis loop properties, on the

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

    Microsoft Academic Search

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

    2001-01-01

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

  7. Observations of an Impurity-driven Hysteresis Behavior in Ice Crystal Growth at Low Pressure

    E-print Network

    Libbrecht, Kenneth G.

    Observations of an Impurity-driven Hysteresis Behavior in Ice Crystal Growth at Low Pressure Abstract. We describe observations of a novel hysteresis behavior in the growth of ice crystals under near the growth velocity vn normal to the surface of a crystal facet in terms of the Hertz-Knudsen formula vn

  8. Why Are Some Hysteresis Loops Shaped Like a Butterfly? Bojana Drincic a

    E-print Network

    Tan, Xiaobo

    Why Are Some Hysteresis Loops Shaped Like a Butterfly? Bojana Drinci´c a , Xiaobo Tan b , Dennis S The contribution of this paper is a framework for relating butterfly-shaped hysteresis maps to simple (single, a unimodal mapping is used to transform simple loops to butterfly loops. For the practically important class

  9. Analytic and experimental studies of a wavelet identification of Preisach model of hysteresis

    Microsoft Academic Search

    Yunhe Yu; Zhengchu Xiao; En-Bing Lin; Nagi Naganathan

    2000-01-01

    Preisach model has enjoyed extensive applications in describing the hysteresis phenomena. An important open question in the analysis of hysteresis using Preisach models is the determination of the model parameters and is referred as the identification problem. However, no general mathematical methods appear to be available for identification and customized identification algorithms must be developed for each specific area of

  10. A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys

    E-print Network

    A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys Jordan E. Massad1-8205 Abstract Thin-film shape memory alloys (SMAs) have become excellent candidates for mi- croactuator hysteresis data. Key words: Shape memory alloy model; thin film; polycrystals. 1 Introduction Shape memory

  11. American History Picture Show

    NSDL National Science Digital Library

    Ms. Bennion

    2009-11-23

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

  12. Modeling of quasistatic magnetic hysteresis with feed-forward neural networks

    SciTech Connect

    Makaveev, Dimitre; Dupre, Luc; De Wulf, Marc; Melkebeek, Jan

    2001-06-01

    A modeling technique for rate-independent (quasistatic) scalar magnetic hysteresis is presented, using neural networks. Based on the theory of dynamic systems and the wiping-out and congruency properties of the classical scalar Preisach hysteresis model, the choice of a feed-forward neural network model is motivated. The neural network input parameters at each time step are the corresponding magnetic field strength and memory state, thereby assuring accurate prediction of the change of magnetic induction. For rate-independent hysteresis, the current memory state can be determined by the last extreme magnetic field strength and induction values, kept in memory. The choice of a network training set is motivated and the performance of the network is illustrated for a test set not used during training. Very accurate prediction of both major and minor hysteresis loops is observed, proving that the neural network technique is suitable for hysteresis modeling. {copyright} 2001 American Institute of Physics.

  13. 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.

  14. 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(+).

  15. Estimation and comparison of flowering curves

    Microsoft Academic Search

    Robert M. Clark; Roy Thompson

    2011-01-01

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

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

    PubMed Central

    Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

    2010-01-01

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

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

    PubMed

    Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

    2010-01-01

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

  18. Back-propagation operation for analog neural network hardware with synapse components having hysteresis characteristics.

    PubMed

    Ueda, Michihito; Nishitani, Yu; Kaneko, Yukihiro; Omote, Atsushi

    2014-01-01

    To realize an analog artificial neural network hardware, the circuit element for synapse function is important because the number of synapse elements is much larger than that of neuron elements. One of the candidates for this synapse element is a ferroelectric memristor. This device functions as a voltage controllable variable resistor, which can be applied to a synapse weight. However, its conductance shows hysteresis characteristics and dispersion to the input voltage. Therefore, the conductance values vary according to the history of the height and the width of the applied pulse voltage. Due to the difficulty of controlling the accurate conductance, it is not easy to apply the back-propagation learning algorithm to the neural network hardware having memristor synapses. To solve this problem, we proposed and simulated a learning operation procedure as follows. Employing a weight perturbation technique, we derived the error change. When the error reduced, the next pulse voltage was updated according to the back-propagation learning algorithm. If the error increased the amplitude of the next voltage pulse was set in such way as to cause similar memristor conductance but in the opposite voltage scanning direction. By this operation, we could eliminate the hysteresis and confirmed that the simulation of the learning operation converged. We also adopted conductance dispersion numerically in the simulation. We examined the probability that the error decreased to a designated value within a predetermined loop number. The ferroelectric has the characteristics that the magnitude of polarization does not become smaller when voltages having the same polarity are applied. These characteristics greatly improved the probability even if the learning rate was small, if the magnitude of the dispersion is adequate. Because the dispersion of analog circuit elements is inevitable, this learning operation procedure is useful for analog neural network hardware. PMID:25393715

  19. Back-Propagation Operation for Analog Neural Network Hardware with Synapse Components Having Hysteresis Characteristics

    PubMed Central

    Ueda, Michihito; Nishitani, Yu; Kaneko, Yukihiro; Omote, Atsushi

    2014-01-01

    To realize an analog artificial neural network hardware, the circuit element for synapse function is important because the number of synapse elements is much larger than that of neuron elements. One of the candidates for this synapse element is a ferroelectric memristor. This device functions as a voltage controllable variable resistor, which can be applied to a synapse weight. However, its conductance shows hysteresis characteristics and dispersion to the input voltage. Therefore, the conductance values vary according to the history of the height and the width of the applied pulse voltage. Due to the difficulty of controlling the accurate conductance, it is not easy to apply the back-propagation learning algorithm to the neural network hardware having memristor synapses. To solve this problem, we proposed and simulated a learning operation procedure as follows. Employing a weight perturbation technique, we derived the error change. When the error reduced, the next pulse voltage was updated according to the back-propagation learning algorithm. If the error increased the amplitude of the next voltage pulse was set in such way as to cause similar memristor conductance but in the opposite voltage scanning direction. By this operation, we could eliminate the hysteresis and confirmed that the simulation of the learning operation converged. We also adopted conductance dispersion numerically in the simulation. We examined the probability that the error decreased to a designated value within a predetermined loop number. The ferroelectric has the characteristics that the magnitude of polarization does not become smaller when voltages having the same polarity are applied. These characteristics greatly improved the probability even if the learning rate was small, if the magnitude of the dispersion is adequate. Because the dispersion of analog circuit elements is inevitable, this learning operation procedure is useful for analog neural network hardware. PMID:25393715

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  1. Bi-stability, hysteresis, and memory of voltage-gated lysenin channels.

    PubMed

    Fologea, Daniel; Krueger, Eric; Mazur, Yuriy I; Stith, Christine; Okuyama, Yui; Henry, Ralph; Salamo, Greg J

    2011-12-01

    Lysenin, a 297 amino acid pore-forming protein extracted from the coelomic fluid of the earthworm E. foetida, inserts constitutively open large conductance channels in natural and artificial lipid membranes containing sphingomyelin. The inserted channels show voltage regulation and slowly close at positive applied voltages. We report on the consequences of slow voltage-induced gating of lysenin channels inserted into a planar Bilayer Lipid Membrane (BLM), and demonstrate that these pore-forming proteins constitute memory elements that manifest gating bi-stability in response to variable external voltages. The hysteresis in macroscopic currents dynamically changes when the time scale of the voltage variation is smaller or comparable to the characteristic conformational equilibration time, and unexpectedly persists for extremely slow-changing external voltage stimuli. The assay performed on a single lysenin channel reveals that hysteresis is a fundamental feature of the individual channel unit and an intrinsic component of the gating mechanism. The investigation conducted at different temperatures reveals a thermally stable reopening process, suggesting that major changes in the energy landscape and kinetics diagram accompany the conformational transitions of the channels. Our work offers new insights on the dynamics of pore-forming proteins and provides an understanding of how channel proteins may form an immediate record of the molecular history which then determines their future response to various stimuli. Such new functionalities may uncover a link between molecular events and macroscopic processing and transmission of information in cells, and may lead to applications such as high density biologically-compatible memories and learning networks. PMID:21945404

  2. 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

  3. The thermodynamic origin of hysteresis in insertion batteries

    NASA Astrophysics Data System (ADS)

    Dreyer, Wolfgang; Jamnik, Janko; Guhlke, Clemens; Huth, Robert; Moškon, Jože; Gaberš?ek, 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 1010-1017 electrode particles constituting a modern battery electrode proceeds at (much) higher voltages than discharging. Most importantly, the hysteresis between the charge and discharge voltage seems not to disappear as the charging/discharging current vanishes. Herein we present, for the first time, a general explanation of the occurrence of inherent hysteretic behaviour in insertion storage systems containing multiple particles. In a broader sense, the model also predicts the existence of apparent equilibria in battery electrodes, the sequential particle-by-particle charging/discharging mechanism and the disappearance of two-phase behaviour at special experimental conditions.

  4. Cumulative growth of minor hysteresis loops in the Kolmogorov model

    SciTech Connect

    Meilikhov, E. Z., E-mail: meilikhov@imp.kiae.ru; Farzetdinova, R. M. [National Research Centre Kurchatov Institute (Russian Federation)] [National Research Centre Kurchatov Institute (Russian Federation)

    2013-01-15

    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.

  5. Phase transition and hysteresis in scale-free network traffic.

    PubMed

    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 phi slightly larger than zero, and we provide an analysis for the optimal value of phi. 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. PMID:17500754

  6. 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.

  7. Hysteresis-free nanoplasmonic pd-au alloy hydrogen sensors.

    PubMed

    Wadell, Carl; Nugroho, Ferry Anggoro Ardy; Lidström, Emil; Iandolo, Beniamino; Wagner, Jakob B; Langhammer, Christoph

    2015-05-13

    The recent market introduction of hydrogen fuel cell cars and the prospect of a hydrogen economy have drastically accelerated the need for safe and accurate detection of hydrogen. In this Letter, we investigate the use of arrays of nanofabricated Pd-Au alloy nanoparticles as plasmonic optical hydrogen sensors. By increasing the amount of Au in the alloy nanoparticles up to 25 atom %, we are able to suppress the hysteresis between hydrogen absorption and desorption, thereby increasing the sensor accuracy to below 5% throughout the investigated 1 mbar to 1 bar hydrogen pressure range. Furthermore, we observe an 8-fold absolute sensitivity enhancement at low hydrogen pressures compared to sensors made of pure Pd, and an improved sensor response time to below one second within the 0-40 mbar pressure range, that is, below the flammability limit, by engineering the nanoparticle size. PMID:25915663

  8. Segmented shape memory alloy actuators using hysteresis loop control

    NASA Astrophysics Data System (ADS)

    Selden, Brian; Cho, Kyujin; Asada, H. Harry

    2006-04-01

    A new approach to the design and control of shape memory alloy (SMA) actuators is presented. SMA wires are divided into many segments and their thermal states are controlled individually as a group of finite state machines. Instead of driving a current to the entire SMA wire and controlling the wire length based on the analog strain-temperature characteristics, the new method controls the binary state (hot or cold) of individual segments and thereby the total displacement is proportional to the length of the heated segments, i.e. austenite phase. Although the thermomechanical properties of SMA are highly nonlinear and uncertain with a prominent hysteresis, segmented binary control is robust and stable, providing characteristics similar to a stepping motor. However, the heating and cooling of each segment to its bi-stable states entail longer time and larger energy for transition. In this paper, an efficient method for improving the speed of response and power consumption is developed by exploiting the inherent hysteresis of SMA. Instead of keeping the extreme temperatures continuously, the temperatures return to intermediate 'hold' temperatures closer to room temperature but sufficient to keep constant phase. Coordination of the multitude of segments having independent thermal states allows for faster response with little latency time even for thick SMA wires. Based on stress dependent thermomechanical characteristics, the hold temperature satisfying a given stress margin is obtained. The new control method is implemented using the Peltier effect thermoelectric devices for selective segment-by-segment heating and cooling. Experiments demonstrate the effectiveness of the proposed method.

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

    PubMed Central

    Wang, Yanzhang; Wu, Shujun; Zhou, Zhijian; Cheng, Defu; Pang, Na; Wan, Yunxia

    2013-01-01

    Based on the core hysteresis features, the RTD-fluxgate core, while working, is repeatedly saturated with excitation field. When the fluxgate simulates, the accurate characteristic model of the core may provide a precise simulation result. As the shape of the ideal hysteresis loop model is fixed, it cannot accurately reflect the actual dynamic changing rules of the hysteresis loop. In order to improve the fluxgate simulation accuracy, a dynamic hysteresis loop model containing the parameters which have actual physical meanings is proposed based on the changing rule of the permeability parameter when the fluxgate is working. Compared with the ideal hysteresis loop model, this model has considered the dynamic features of the hysteresis loop, which makes the simulation results closer to the actual output. In addition, other hysteresis loops of different magnetic materials can be explained utilizing the described model for an example of amorphous magnetic material in this manuscript. The model has been validated by the output response comparison between experiment results and fitting results using the model. PMID:24002230

  10. 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.)

  11. ?-function for analytic curves

    Microsoft Academic Search

    I. K. Kostov; I. Krichever; M. Mineev-Weinstein; P. B. Wiegmann; A. Zabrodin

    We review the concept of ?-function for simple analytic curves. The ?-function gives a formal solution to the 2D inverse potential problem and appears as the ?-function of the integrable hierarchy which describes conformal maps of simply- connected domains bounded by analytic curves to the unit disk. The ?-function also emerges in the context of topological gravity and enjoys an

  12. The Curved Cube

    NSDL National Science Digital Library

    Hill, David R.

    2003-02-24

    Take a solid cube with rods attached at diagonally opposite vertices. Hold the rods horizontally and rapidly spin the cube. (See Figure 1.) You should see a curved outline formed by the spinning cube. The objective of this demos is to discover how the straight edges of the cube become curved. The demo is physically based, but can be simulated within various software packages.

  13. 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…

  14. Analyzing population growth curves

    Microsoft Academic Search

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

    2008-01-01

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

  15. Famous Curves Index

    NSDL National Science Digital Library

    Throughout history, there have been many famous curves. In this case, the famous curves profiled here have names such as rhodonea, right strophoid, and the Kampyle of Eudoxus. These curves belong to the world of the mathematical sciences, and they are offered up for teachers and the generally curious by the staff at the School of Mathematics and Statistics at the University of St. Andrews. Visitors can scroll through the complete list of curves (there are over eighty here), and click on each one for an illustration and a listing of the equation that would create such a curve. The site is rounded out by an interactive map that lets users learn about the birthplaces of famous mathematicians from Leibniz to Babbage.

  16. 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.

  17. Enhancement of coil-stretch hysteresis by self-concentration in polymer solutions

    E-print Network

    Ranganathan Prabhakar

    2013-01-31

    The effect of concentration on coil-stretch hysteresis in extensional flows of polymer solutions is examined with insights from Brownian dynamics simulations of isolated chains and scaling theory for non-dilute solutions. In the hysteresis regime, stretched molecules pervade larger volumes than equilibrium coils. For such chains, intermolecular overlap and hydrodynamic screening crossover set in at concentrations much smaller than the critical overlap concentration $c^\\ast$ for equilibrium coils. The width of the hysteresis window is consequently strongly enhanced around $c^\\ast$.

  18. 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.

  19. Laboratory and Field Investigations of Dynamic Effects in Soil Water Retention Curve

    NASA Astrophysics Data System (ADS)

    Chiu, Yung-Chia; Tseng, Yen-Huiang; Ye, Jiun-Yan

    2015-04-01

    The unsaturated soil is a multi-phase system and the embedded physical mechanisms and chemical reactions are very complicated. The characteristics of groundwater flow and mechanisms of mass transport are still ambiguous so far. In order to fully understand the flow and transport in the unsaturated zone, the soil water retention curve plays an important role in description of water flow. However, the measurements and calculations of soil water retention curve are usually obtained under the static condition or steady state (equilibrium), in which the dynamic effects (non-equilibrium) are not considered, and the obtained relationship between capillary pressure and saturation is skeptical. Therefore, the sandbox experiments and field tests will be conducted to discuss the dynamic effects in the soil water retention curve and hysteresis effect in this study. In the laboratory, the relations between capillary pressure, saturation, the rate of change of water content, and dynamic constant are evaluated through different setting of boundary conditions and different sizes of particles. In the field, the tests are conducted to describe the soil water retention curve through the rain simulator and artificial evaporation. Besides, the dynamic dewpoint potentiameter is used to analyze the hysteresis effect of soil samples, and its results are compared with the results obtained from sandbox and field experiments. Finally, through a series of experiments, the relationship between capillary pressure and saturation under the dynamic effects is established, and the associated theories and mechanisms are discussed. The works developed in this study can provide as reference tools for the hydrogeological investigation and contaminated site remediation in the future. Keywords: capillary pressure, saturation, soil water retention curve, hysteresis, sandbox experiment, field test

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

    PubMed Central

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

    2013-01-01

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

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

    Microsoft Academic Search

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

    2011-01-01

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

  2. Elliptic Curves Kenneth A. Ribet

    E-print Network

    Ribet, Kenneth A.

    Elliptic Curves Kenneth A. Ribet UC Berkeley PARC Forum October 17, 2008 Kenneth A. Ribet Elliptic Curves #12;In talking about elliptic curves, one can do no better than to quote the Yale mathematician endlessly on elliptic curves. (This is not a threat.) Kenneth A. Ribet Elliptic Curves #12;Although I have

  3. 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.

  4. 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.

  5. IEEE Transactions on Automation Science and Engineering Compensation of Scanner Creep and Hysteresis

    E-print Network

    Southern California, University of

    IEEE Transactions on Automation Science and Engineering Compensation of Scanner Creep uncertainties associated with creep and hysteresis, and supports automated, computer-controlled manipulation) and by automation, which bypasses the time- consuming

  6. 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

  7. Exploiting Hysteresis in a CMOS Bu er Radu M. Secareanu, Victor Adler, and Eby G. Friedman

    E-print Network

    Friedman, Eby G.

    Exploiting Hysteresis in a CMOS Bu er Radu M. Secareanu, Victor Adler, and Eby G. Friedman@ece.rochester.edu, adler@ece.rochester.edu, friedman@ece.rochester.edu Abstract| A high drive CMOS bu er circuit character

  8. Author's personal copy On non-monotonic rate dependence of stress hysteresis of superelastic shape

    E-print Network

    Sun, Qing-Ping

    -induced for- ward/reverse phase transition with latent heat release/absorption. By solving the convective heat the iso- thermal damping capacity (energy dissipation per unit material volume, i.e., hysteresis loop area

  9. 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 ...

  10. Origin of Plate Tectonics by Grain-Damage: Hysteresis and Plate-Like States

    NASA Astrophysics Data System (ADS)

    Bercovici, D.

    2015-05-01

    Grain-damage theory provides a physical framework to explain the conditions for generating plate tectonics on rocky planets. I present new work exploring grain-damage hysteresis which predicts when plate-like states on planets can exist.

  11. Logistic Curve Demo

    NSDL National Science Digital Library

    Roberts, Lila F.

    2002-02-03

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

  12. Experimental study and theoretical interpretation of hysteresis loops and Henkel plots in soft magnetic materials

    Microsoft Academic Search

    V. Basso; M. Lo Bue; A. Magni; G. Ummarino; G. Bertotti

    1994-01-01

    In this paper we discuss an application of the moving Preisach model (MPM) and the zero-temperature Sherrington-Kirkpatrick spin-glass model (SKM) to the interpretation of hysteresis phenomena in soft materials, with particular attention to the analogies and differences between the models. Both models are compared with hysteresis measurements performed on strips of amorphous Fe-B-Si alloy. We describe experimental data using the

  13. A robust hysteresis current-controlled PWM inverter for linear PMSM driven magnetic suspended positioning system

    Microsoft Academic Search

    Bor-Jehng Kang; Chang-Ming Liaw

    2001-01-01

    Hysteresis current-controlled pulsewidth modulation (PWM) is very robust but it possesses nonconstant switching frequency, and it is difficult to use for high-performance position servo applications. This paper presents a robust hysteresis current-controlled PWM scheme for a magnetic suspended positioning system driven by an inverter-fed linear permanent-magnet synchronous motor having improved performance in these two areas. In the proposed control scheme,

  14. Magnetostrictive hysteresis of TbCo\\/CoFe multilayers and magnetic domains

    Microsoft Academic Search

    J.-Ph. Jay; F. Petit; J. Ben Youssef; M. V. Indenbom; A. Thiaville; J. Miltat

    2006-01-01

    Magnetic and magnetostrictive hysteresis loops of TbCo\\/CoFe multilayers under field applied along the hard magnetization axis are studied using vectorial magnetization measurements, optical deflectometry, and magneto-optical Kerr microscopy. Even a very small angle misalignment between hard axis and magnetic field direction is shown to drastically change the shape of magnetization and magnetostrictive torsion hysteresis loops. Two kinds of magnetic domains

  15. Magnetostrictive hysteresis of TbCo\\/CoFe multilayers and magnetic domains

    Microsoft Academic Search

    F. Petit; J. Ben Youssef; M. V. Indenbom; A. Thiaville; J. Miltat

    2005-01-01

    Magnetic and magnetostrictive hysteresis loops of TbCo\\/CoFe multilayers under\\u000afield applied along the hard magnetization axis are studied using vectorial\\u000amagnetization measurements, optical deflectometry and magneto optical Kerr\\u000amicroscopy. Even a very small angle misalignment between hard axis and magnetic\\u000afield direction is shown to drastically change the shape of magnetization and\\u000amagnetostrictive torsion hysteresis loops. Two kinds of magnetic

  16. Control of deep-hysteresis aeroengine compressors. I. A Moore-Greitzer type model

    Microsoft Academic Search

    Hsin-Hsiung Wang; Miroslav KrstiC; Michael Larsen

    1997-01-01

    While the famous Moore-Greitzer cubic model (MG3) provides a good qualitative description of open-loop dynamic behavior of an axial compressor, it does not capture the main difficulties for control design. In particular, it fails to exhibit the so-called “right-skew” property which distinguishes the deep hysteresis observed on high-performance axial compressors from a small hysteresis present in the MG3 model. We

  17. Hysteresis, microstructure, and magneto-optical recording in Co\\/Pt and Co\\/Pd multilayers

    Microsoft Academic Search

    W. B. Zeper; H. W. van Kesteren; B. A. J. Jacobs; J. H. M. Spruit; P. F. Carcia

    1991-01-01

    The factors that influence the coercive field Hc and the shape of the magnetic hysteresis loop for Co\\/Pt multilayers (MLs), applied as a magneto-optical (MO) recording medium, have been investigated. The hysteresis loop of MLs, made by evaporation of Kr sputtering, became more rectangular when the total film thickness was reduced, i.e., the saturation field Hs decreased and the nucleation

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

    Microsoft Academic Search

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

    2000-01-01

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

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

    Microsoft Academic Search

    Woong Kim; Ali Javey; Ophir Vermesh; Qian Wang; Yiming Li; Hongjie Dai

    2003-01-01

    Carbon nanotube field-effect transistors commonly comprise nanotubes lying on SiO2 surfaces exposed to the ambient environment. It is shown here 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 persists for the transistors in vacuum since the SiO2- bound water does

  20. Hysteresis Affects Approximate Number Discrimination in Young Children

    PubMed Central

    Odic, Darko; Hock, Howard; Halberda, Justin

    2015-01-01

    Perceptual decisions are often affected not only by the evidence gathered during a trial but also by the history of preceding trials. This effect—termed perceptual hysteresis—provides evidence for how perceptual information is represented and how it is used. The present research focuses on how the difficulty of preceding trials affects subsequent ones—we find that how well 5-year-old children perform in a 2-alternative forced-choice numerical discrimination task depends on whether they have had a prior history of easier discriminations or a prior history of harder discriminations. Furthermore, this effect is modulated by the feedback children receive. In 3 experiments, we demonstrate that these effects are not related to practice or loss of interest due to negative feedback, or simply to trial difficulty or discriminability. Instead, children appear to have state-dependent confidence states such that prolonged experience making low-confidence decisions degrades performance, whereas prolonged experience making high-confidence decisions improves it. These results are discussed in the context of dynamical psychophysics, representations of confidence, and work on children’s and adults’ number perception abilities. PMID:23163765

  1. 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

  2. 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

  3. Avalanches and hysteresis in frustrated superconductors and XY spin glasses

    NASA Astrophysics Data System (ADS)

    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.

  4. Droplet evaporation dynamics on a superhydrophobic surface with negligible hysteresis.

    PubMed

    Dash, Susmita; Garimella, Suresh V

    2013-08-27

    We report on experiments of droplet evaporation on a structured superhydrophobic surface that displays very high contact angle (CA ? 160 deg), and negligible contact angle hysteresis (<1 deg). The droplet evaporation is observed to occur in a constant-contact-angle mode, with contact radius shrinking for almost the entire duration of evaporation. Experiments conducted on Teflon-coated smooth surface (CA ? 120 deg) as a baseline also support an evaporation process that is dominated by a constant-contact-angle mode. The experimental results are compared with an isothermal diffusion model for droplet evaporation from the literature. Good agreement is observed for the Teflon-coated smooth surface between the analytical expression and experimental results in terms of the total time for evaporation, transient volume, contact angle, and contact radius. However, for the structured superhydrophobic surface, the experiments indicate that the time taken for complete evaporation of the droplet is greater than the predicted time, across all droplet volumes. This disparity is attributed primarily to the evaporative cooling at the droplet interface due to the high aspect ratio of the droplet and also the lower effective thermal conductivity of the substrate due to the presence of air gaps. This hypothesis is verified by numerically evaluating the temperature distribution along the droplet interface. We propose a generalized relation for predicting the instantaneous volume of droplets with initial CA > 90 deg, irrespective of the mode of evaporation. PMID:23952149

  5. 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.

  6. Modeling and analysis of hysteresis by harmonic balance method

    NASA Astrophysics Data System (ADS)

    Cheng, Weiying; Saito, Yoshifuru

    2015-05-01

    B-H loop and its modeling are essential for ferromagnetic material characterization and electromagnetic simulation. The objective of this study was to characterize material change by analyzing the corresponding B-H loops and construct a general B-H model for electromagnetic simulation. A B-H loop was decomposed in terms of either ideal or normal magnetization curves, and the respective curves are single-valued functions of B and dB, which can be constructed using harmonic balance method. The B-H loop analysis and modeling were simplified by the loop decomposition approach.

  7. ELLIPTIC CURVE CRYPTOGRAPHY ON SMART CARDS WITHOUT COPROCESSORS

    E-print Network

    ELLIPTIC CURVE CRYPTOGRAPHY ON SMART CARDS WITHOUT COPROCESSORS Adam D. Woodbury Electrical how an elliptic curve cryptosystem can be imple- mented on very low cost microprocessors's inversion algorithm is used for the group operation. We show that an elliptic curve scalar multiplication

  8. Fast Elliptic Curve Arithmetic and Improved Weil Pairing Evaluation

    E-print Network

    Lauter, Kristin

    Fast Elliptic Curve Arithmetic and Improved Weil Pairing Evaluation Kirsten EisentrË?ager 1 multiplication on a general elliptic curve by an estimated 3.8% to 8.5% over the best known general methods when multiplication and to the Elliptic Curve Method of factorization. We show how this improvement together

  9. ELLIPTIC CURVE CRYPTOGRAPHY ON SMART CARDS WITHOUT COPROCESSORS

    E-print Network

    ELLIPTIC CURVE CRYPTOGRAPHY ON SMART CARDS WITHOUT COPROCESSORS Adam D. Woodbury Electrical how an elliptic curve cryptosystem can be imple­ mented on very low cost microprocessors and Tsujii's inversion algorithm is used for the group operation. We show that an elliptic curve scalar

  10. Design of an efficient elliptic curve cryptography coprocessor

    Microsoft Academic Search

    B. MuthuKumar; S. Jeevanantharr

    2009-01-01

    Elliptic curve cryptography plays a crucial role in networking and communication security. FPGA based architecture of elliptic curve cryptography coprocessor is proposed in this paper. The coprocessor contains the operation over binary finite fields, point adding, doubling and scalar multiplication on elliptic curve. In this coprocessor a new type of FPGA-based modular multiplier architecture is proposed. Experiment results show that

  11. On the coordinate functions of Levy's dragon curve

    E-print Network

    Kawamura, Kiko

    On the coordinate functions of L´evy's dragon curve Pieter C. Allaart and Kiko Kawamura University of North Texas February 9, 2006 Abstract L´evy's dragon curve [P. L´evy, Les courbes planes ou gauches et for the coordi- nate functions of L´evy's dragon curve, and show that the 3 2 -dimensional Hausdorff measure

  12. On the coordinate functions of Levy's dragon curve

    E-print Network

    Allaart, Pieter

    On the coordinate functions of L´evy's dragon curve Pieter C. Allaart and Kiko Kawamura University of North Texas August 16, 2005 Abstract L´evy's dragon curve [P. L´evy, Les courbes planes ou gauches et for the coordi- nate functions of L´evy's dragon curve, and show that the 3 2 -dimensional Hausdorff measure

  13. Observing the yield curve of compacted pack ice

    Microsoft Academic Search

    Keguang Wang

    2007-01-01

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

  14. 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 (surfaces. Subsequently fitting the Lippmann-Young 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.

  15. 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.

  16. Phase nucleation in curved space.

    PubMed

    Gómez, Leopoldo R; García, Nicolás A; Vitelli, Vincenzo; Lorenzana, José; Vega, Daniel A

    2015-01-01

    Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature. PMID:25896725

  17. Hysteresis and wall-effects in low Reynolds number propulsion by driven elastic filaments

    NASA Astrophysics Data System (ADS)

    Clark, Sarah; Ranganathan, Prabhakar; Friend, James

    2009-11-01

    There is currently intense interest in developing micron-sized robots for uses such as minimally invasive surgery. Although progress has been made in miniaturizing the motor, the hydrodynamic behavior of associated propellers is far from being fully understood. An example is an elastic filament driven by a torque at one end where the shape assumed by the filament is strongly coupled to the hydrodynamics forces. Investigation of these dynamics has only recently commenced, for instance Manghi et al. [PRL 96, 068101 (2006)] uncovered an intriguing shape transition in an elastic filament spun in a bulk fluid. Since such transitions can be expected to have a crucial bearing on the operation of microbot swimmers we examine this behavior in detail with simulations. We also study the effect of planar no-slip walls on the propulsion characteristics. The slender filament is represented as a bead-spring chain and inter-bead hydrodynamic-interactions are described using the appropriate Greens functions. We study the origin of the shape transition and hysteresis in detail and show the relationship to sedimenting filaments. We show that the presence of a boundary either perpendicular or parallel to the axis of the applied torque has a significant effect on the overall motion. We also point out the possible detrimental consequences of these effects on operation of microbots in the vicinity of conduit walls.

  18. 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

  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. 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

  1. Development of a portable mechanical hysteresis measurement and imaging system for impact characterization in honeycomb sandwich structures

    SciTech Connect

    Barnard, Daniel J.; Hsu, David K. [Center for NDE, Iowa State University, Ames, IA 50011 (United States)

    2011-06-23

    Honeycomb sandwich materials are commonly used for aero-structures, but because the outer skins are typically thin, 2-10 plys, the structures are susceptible to impact damage. NDI methods such as tap tests, bond testers and TTU ultrasound are successfully deployed to find impact damage, but identifying the type/degree of damage is troublesome. As the type/degree of impact damage guides decisions by the maintenance, repair and overhaul (MRO) community regarding repair, the ability to characterize impacts is of interest. Previous work demonstrated that additional impact characterization may be gleaned from hysteresis loop area, as determined from an out-of-plane load-vs-displacement plot, where this parameter shows a correlation with impact energy. This presentation reports on current work involving the development of a portable hysteresis measurement and imaging system based on an instrumented tapper. Data processing and analysis methods that allow production of the load/displacement data from a single accelerometer are discussed, with additional reporting of tests of software to automatically vary pixel size during scanning to decrease C-scans inspection time.

  2. Kinetic and thermodynamic hysteresis imposed by intercalation of proflavine in ferrocene-modified double-stranded DNA.

    PubMed

    Gebala, Magdalena; La Mantia, Fabio; Schuhmann, Wolfgang

    2013-07-22

    Surface-confined immobilized redox species often do not show the expected zero peak separation in slow-scan cyclic voltammograms. This phenomenon is frequently associated to experimental drawbacks and hence neglected. However, a nonzero peak separation, which is common to many electrochemical systems with high structural flexibility, can be rationally assigned to a thermodynamic hysteresis. To study this phenomenon, a surface-confined redox species was used. Specifically, a DNA strand which is tagged with ferrocene (Fc) moieties at its 5' end and its complementary capture probe is thiolated at the 3' end was self-assembled in a monolayer at a Au electrode with the Fc moieties being located at the bottom plane of the double-stranded DNA (dsDNA). The DNA-bound Fc undergoes rapid electron transfer with the electrode surface as evaluated by fast scan cyclic voltammetry. The electron transfer is sensitive to the ion transport along the DNA strands, a phenomenon which is modulated upon specific intercalation of proflavine into surface-bound dsDNA. The electron transfer rate of the Fc(0/+) redox process is influenced by the cationic permselectivity of the DNA monolayer. In addition to the kinetic hindrance, a thermodynamic effect correlated with changes in the activity coefficients of the Fc(0/+) moieties near the gold-dsDNA interface is observed and discussed as source of the observed hysteresis causing the non-zero peak separation in the voltammograms. PMID:23674389

  3. Evolution of water repellency of organic growing media used in Horticulture and consequences on hysteretic behaviours of the water retention curve

    NASA Astrophysics Data System (ADS)

    Michel, Jean-Charles; Qi, Guifang; Charpentier, Sylvain; Boivin, Pascal

    2010-05-01

    Most of growing media used in horticulture (particularly peat substrates) shows hysteresis phenomena during desiccation and rehydration cycles, which greatly affects their hydraulic properties. The origins of these properties have often been related to one or several of the specific mechanisms such as the non-geometrical uniformity of the pores (also called ‘ink bottle' effect), presence of trapped air, shrinkage-swelling phenomena, and changes in water repellency. However, recent results showed that changes in wettability during desiccation and rehydration could be considered as one of the main factors leading to hysteretic behaviour in these materials with high organic matter contents (Naasz et al., 2008). The general objective was to estimate the evolutions of changes in water repellency on the water retention properties and associated hysteresis phenomena in relation to the intensity and the number of drying/wetting cycles. For this, simultaneous shrinkage/swelling and water retention curves were obtained using method previously developed for soil shrinkage analysis by Boivin (2006) that we have adapted for growing media and to their physical behaviours during rewetting. The experiment was performed in a climatic chamber at 20°C. A cylinder with the growing medium tested was placed on a porous ceramic disk which is used to control the pressure and to full/empty water of the sample. The whole of the device was then placed on a balance to record the water loss/storage with time; whereas linear displacement transducers were used to measure the changes in sample height and diameter upon drying and wetting in the axial and radial directions. Ceramic cups (2 cm long and 0.21 cm diameter) connected to pressure transducers were inserted in the middle of the samples to record the water pressure head. In parallell, contact angles were measured by direct droplet method at different steps during the drying/rewetting cycles. First results obtained on weakly decomposed peat samples with or without surfactants showed isotropic shrinkage and swelling, and highlighted hysteresis phenomena in relation to the intensity of drying/wetting cycle. Contact angle measurements are in progress. Other measurements on highly decomposed peat (more repellent than weakly decomposed), composted pine bark (without volume change during dryin/wetting cycles), and coco fiber (expected as non repellent organic growing media) are also in progress.

  4. Hysteresis of haptic vertical and straight ahead in healthy human subjects

    PubMed Central

    2012-01-01

    Background The subjective haptic vertical (SHV) task requires subjects to adjust the roll orientation of an object, mostly in the roll plane, in such a way that it is parallel to perceived direction of gravity. Previously we found a tendency for clockwise rod rotations to deviate counter-clockwise and vice versa, indicating hysteresis. However, the contributing factors remained unclear. To clarify this we characterized the SHV in terms of handedness, hand used, direction of hand rotation, type of grasping (wrap vs. precision grip) and gender, and compared findings with perceived straight-ahead (PSA). Healthy subjects repetitively performed adjustments along SHV (n?=?21) and PSA (n?=?10) in complete darkness. Results For both SHV and PSA significant effects of the hand used and the direction of rod/plate rotation were found. The latter effect was similar for SHV and PSA, leading to significantly larger counter-clockwise shifts (relative to true earth-vertical and objective straight-ahead) for clockwise rotations compared to counter-clockwise rotations irrespective of the handedness and the type of grip. The effect of hand used, however, was opposite in the two tasks: while the SHV showed a counter-clockwise bias when the right hand was used and no bias for the left hand, in the PSA a counter-clockwise bias was obtained for the left hand without a bias for the right hand. No effects of grip and handedness (studied for SHV only) on accuracy were observed, however, SHV precision was significantly (p?hysteresis and are likely not related to gravitational pull, as they were observed in both planes tested, i.e. parallel and perpendicular to gravity. Short-term adaptation that shifts attention towards previous adjustment positions may provide an explanation for such biases of spatial orientation in both the horizontal and frontal plane. PMID:22998034

  5. Elements of QFT in Curved Space-Time Ilya L. Shapiro

    E-print Network

    Rossak, Wilhelm R.

    shows matter how to move. · Matter shows space how to curve. Ilya Shapiro, Lectures on curved-space QFT holes. 2) Isotropic and homogeneous metric. Universe. Ilya Shapiro, Lectures on curved-space QFTElements of QFT in Curved Space-Time Ilya L. Shapiro Universidade Federal de Juiz de Fora, MG

  6. Migration of a coarse fluvial sediment pulse detected by hysteresis in bedload generated seismic waves

    NASA Astrophysics Data System (ADS)

    Roth, D. L.; Finnegan, N. J.; Brodsky, E. E.; Cook, K. L.; Stark, C. P.; Wang, H. W.

    2014-10-01

    Seismic signals near rivers are partially composed of the elastic waves generated by bedload particles impacting the river bed. In this study, we explore the relationship between this seismic signal and river bedload transport by analyzing high-frequency broadband seismic data from multiple stations along the Chijiawan River in northern Taiwan following the removal of a 13 m check dam. This dam removal provides a natural experiment in which rapid and predictable changes in the river's profile occur, which in turn enables independent constraints on spatial and temporal variation in bedload sediment transport. We compare floods of similar magnitudes with and without bedload transport, and find that the amplitude of seismic shaking produced at a given river stage changes over the course of a single storm when bedload transport is active. Hysteresis in the relationship between bedload transport and river stage is a well-documented phenomenon with multiple known causes. Consequently, previous studies have suggested that hysteresis observed in the seismic amplitude-stage response is the signature of bedload transport. Field evidence and stream profile evolution in this study corroborate that interpretation. We develop a metric (?) for the normalized magnitude of seismic hysteresis during individual floods. This metric appears to scale qualitatively with total bedload transport at each seismic station, indicating a dominance of transport on the rising limbs of both storms. We speculate that hysteresis at this site arises from time-dependent evolution of the bed, for example due to grain packing, mobile armoring, or the temporal lag between stage and bedform growth. ? reveals along-stream variations in hysteresis for each storm, with a peak in hysteresis further downstream for the second event. The pattern is consistent with a migrating sediment pulse that is a predicted consequence of the dam removal. Our results indicate that hysteresis in the relationship between seismic wave amplitude and river stage may track sediment transport.

  7. IGMtransmission: Transmission curve computation

    NASA Astrophysics Data System (ADS)

    Harrison, Christopher M.; Meiksin, Avery; Stock, David

    2015-04-01

    IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.

  8. Magnetic hysteresis and relaxation in Ag-sheathed TlBaCaCuO (1223) and Bi(Pb)SrCaCuO (2223) superconducting tapes

    SciTech Connect

    Kung, P.J.; Maley, M.P.; Coulter, J.Y.; Willis, J.O.; Peterson, D.E. [Los Alamos National Lab., NM (United States); McHenry, M.E. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Metallurgical Engineering and Materials Science; Wahlbeck, P.G. [Wichita State Univ., KS (United States). Dept. of Chemistry

    1992-05-01

    Magnetic hysteresis (7--75 K in magnetic fields up to 5 T) and relaxation characteristics (5--50 K in magnetic fields up to 2 T) have been measured with the field perpendicular to the surface of Ag-sheathed TlBaCaCuO (1223 phase) and Bi(Pb)SrCaCuO (2223 phase) superconducting tapes. A study of the difference in the magnetic hysteresis between precursor powders and as-processed tapes was also carried out. The relaxation data were curve-fit using a rate equation for thermally activated flux motion, U{sub eff}/[kG(T)] = {minus}T[ln(dM/dt) {minus} ln (H{omega}{sub o} a/2{pi}d)] with the temperature dependence of U{sub eff} scaled by the functional form G(T) = 1 {minus} (T/Tx){sup 2}. By comparing the results obtained from magnetic characterization with those from transport current measurement, these observations suggest that (1) Tl-1223 tapes have a weaker field dependence for J{sub c} at T > 35 K than Bi-2223 tapes due to the special crystal structure of the 1223 phase, and (2) weak links limit the transport critical current densities in Tl-1223 tapes to 10{sup 3} A/cm{sup 2} at 5 T and 35 K, for instance.

  9. Magnetic hysteresis and relaxation in Ag-sheathed TlBaCaCuO (1223) and Bi(Pb)SrCaCuO (2223) superconducting tapes

    SciTech Connect

    Kung, P.J.; Maley, M.P.; Coulter, J.Y.; Willis, J.O.; Peterson, D.E. (Los Alamos National Lab., NM (United States)); McHenry, M.E. (Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Metallurgical Engineering and Materials Science); Wahlbeck, P.G. (Wichita State Univ., KS (United States). Dept. of Chemistry)

    1992-01-01

    Magnetic hysteresis (7--75 K in magnetic fields up to 5 T) and relaxation characteristics (5--50 K in magnetic fields up to 2 T) have been measured with the field perpendicular to the surface of Ag-sheathed TlBaCaCuO (1223 phase) and Bi(Pb)SrCaCuO (2223 phase) superconducting tapes. A study of the difference in the magnetic hysteresis between precursor powders and as-processed tapes was also carried out. The relaxation data were curve-fit using a rate equation for thermally activated flux motion, U{sub eff}/(kG(T)) = {minus}T(ln(dM/dt) {minus} ln (H{omega}{sub o} a/2{pi}d)) with the temperature dependence of U{sub eff} scaled by the functional form G(T) = 1 {minus} (T/Tx){sup 2}. By comparing the results obtained from magnetic characterization with those from transport current measurement, these observations suggest that (1) Tl-1223 tapes have a weaker field dependence for J{sub c} at T > 35 K than Bi-2223 tapes due to the special crystal structure of the 1223 phase, and (2) weak links limit the transport critical current densities in Tl-1223 tapes to 10{sup 3} A/cm{sup 2} at 5 T and 35 K, for instance.

  10. Generating artificial light curves: revisited and updated

    NASA Astrophysics Data System (ADS)

    Emmanoulopoulos, D.; McHardy, I. M.; Papadakis, I. E.

    2013-08-01

    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 randomization 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 density functions (PDFs). In this study, we propose a simple method which is able to precisely reproduce light curves which match both the PSD and the PDF of either an observed light curve or a theoretical model. The PDF can be representative of either the parent distribution or the actual distribution of the observed data, depending on the study to be conducted for a given source. The final artificial light curves contain all of the statistical and variability properties of the observed source or theoretical model, i.e. the same PDF and PSD, respectively. Within the framework of Reproducible Research, the code and the illustrative example used in this paper are both made publicly available in the form of an interactive MATHEMATICA notebook.

  11. Hierarchically structured re-entrant microstructures for superhydrophobic surfaces with extremely low hysteresis

    NASA Astrophysics Data System (ADS)

    Hu, Huan; Swaminathan, Vikhram V.; Zamani Farahani, Mahmoud Reza; Mensing, Glennys; Yeom, Junghoon; Shannon, Mark A.; Zhu, Likun

    2014-09-01

    This paper reports a new type of hierarchically structured surface consisting of re-entrant silicon micropillars with silicon nanowires atop for superhydrophobic surface with extremely low hysteresis. Re-entrant microstructures were fabricated on a silicon substrate through a customized one-mask microfabrication process while silicon nanopillars were created on the entire surface of microstructures, including sidewalls, by a metal-assisted-chemical etching process. The strategy of constructing hierarchical surfaces aims to reduce the actual contact area between liquid and top part of solid surface, thereby increasing the contact angle and reducing the sliding angle. The strategy of using re-entrant profile of the microstructure aims to prevent a liquid droplet from falling into cavities of roughened structures and decrease the actual contact area between the liquid droplet and sidewalls of solid structures, therefore reducing adhesion forces acting on the liquid droplet. Our measurement shows that the surface incorporating both hierarchical and re-entrant strategies exhibits a sliding angle as low as 0.5°, much lower than sliding angles of surfaces only incorporating either one of the strategies.

  12. Self-tensioning aquatic caddisfly silk: Ca2+-dependent structure, strength, and load cycle hysteresis.

    PubMed

    Ashton, Nicholas N; Roe, Daniel R; Weiss, Robert B; Cheatham, Thomas E; Stewart, Russell J

    2013-10-14

    Caddisflies are aquatic relatives of silk-spinning terrestrial moths and butterflies. Casemaker larvae spin adhesive silk fibers for underwater construction of protective composite cases. The central region of Hesperophylax sp. H-fibroin contains a repeating pattern of three conserved subrepeats, all of which contain one or more (SX)n motifs with extensively phosphorylated serines. Native silk fibers were highly extensible and displayed a distinct yield point, force plateau, and load cycle hysteresis. FTIR spectroscopy of native silk showed a conformational mix of random coil, ?-sheet, and turns. Exchanging multivalent ions with Na(+) EDTA disrupted fiber mechanics, shifted the secondary structure ratios from antiparallel ?-sheet toward random coil and turns, and caused the fibers to shorten, swell in diameter, and disrupted fiber birefringence. The EDTA effects were reversed by restoring Ca(2+). Molecular dynamic simulations provided theoretical support for a hypothetical structure in which the (pSX)n motifs may assemble into two- and three-stranded, Ca(2+)-stabilized ?-sheets. PMID:24050221

  13. Dynamic characterization of hysteresis elements in mechanical systems. II. Experimental validation

    NASA Astrophysics Data System (ADS)

    Symens, W.; Al-Bender, F.

    2005-03-01

    The industrial demand for machine tools with ever increasing speed and accuracy calls for a closer look at the physical phenomena that are present at small movements of those machine's slides. One of these phenomena, and probably the most dominant one, is the dependence of the friction force on displacement that can be described by a rate-independent hysteresis function with nonlocal memory. The influence of this highly nonlinear effect on the dynamics of the system has been theoretically analyzed in Part I of this paper. This part (II) aims at verifying these theoretical results on three experimental setups. Two setups, consisting of linearly driven rolling element guideways, have been built to specifically study the hysteretic friction behavior. The experiments performed on these specially designed setups are then repeated on one axis of an industrial pick-and-place device, driven by a linear motor and guided by commercial guideways. The results of the experiments on all the setups agree qualitatively well with the theoretically predicted ones and point to the inherent difficulty of accurate quantitative identification of the hysteretic behavior. They further show that the hysteretic friction behavior has a direct bearing on the dynamics of machine tools and its presence should therefore be carefully considered in the dynamic identification process of these systems.

  14. Fe-Ti-O exchange at high temperature and thermal hysteresis

    NASA Astrophysics Data System (ADS)

    Charilaou, M.; Löffler, J. F.; Gehring, A. U.

    2011-05-01

    In this study, the Fe-Ti-O exchange behaviour between the systems hemo-ilmenite (y)FeTiO3-(1 -y)Fe2O3 and titano-magnetite (x)Fe2TiO4-(1 -x)Fe3O4 was investigated in the temperature range from 900 to 1400 K in an inert Ar atmosphere. Starting from a mixture of hematite and ilmenite with a fixed mol per cent, heat treatment generates a self-adjusting chemical equilibrium between hemo-ilmenite and titano-magnetite solid solution by means of interdiffusion and Fe3+? Fe2+ reduction. Structural and magnetic characterization reveals that hemo-ilmenite is stable at all temperatures, whereas titano-magnetite shows increasing Ti-content with increasing treatment temperature. Heating-cooling cycles were performed for a sample to mimic slow cooling and study its effects on the two solid solutions. The magnetic properties of that sample exhibit thermal hysteresis during these cycles, as the Ti departs from titano-magnetite and thus leads to a new chemical equilibrium. The experimental data provide insight into the dynamics of the formation of Fe-Ti-O phases formed under varying conditions in geological systems.

  15. Predator-prey reversal: a possible mechanism for ecosystem hysteresis in the North Sea?

    PubMed

    Fauchald, Per

    2010-08-01

    Removal of large predatory fishes from marine ecosystems has resulted in persistent ecosystem shifts, with collapsed predator populations and super-abundant prey populations. One explanation for these shifts is reversals of predator-prey roles that generate internal feedbacks in the ecosystems. Pelagic forage fish are often predators and competitors to the young life stages of their larger fish predators. I show that cod recruitment in the North Sea has been negatively related to the spawning-stock biomass of herring for the last 44 years. Herring, together with the abundance of Calanus finmarchicus, the major food for cod larvae, were the main predictors of cod recruitment. These predictors were of equivalent importance, worked additively, and explained different parts of the dynamics in cod recruitment. I suggest that intensive harvesting of cod has released herring from predator control, and that a large population of herring suppresses cod recruitment through predation on eggs and larvae. This feedback mechanism can promote alternative stable states and therefore cause hysteresis to occur under changing conditions; however, harvesting of herring might at present prevent a shift in the ecosystem to a herring-dominated state. PMID:20836439

  16. Static friction threshold effects on hysteresis and frequency spectra in rocks

    SciTech Connect

    Kadish, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-06-01

    Static friction in rocks is modeled as a threshold phenomenon. An inverse problem in ground motion is analyzed for propagation in a medium with an arbitrary number of fractures at which static friction thresholds determine the onset of slippage. It is shown that seismic source dynamics inferred from surface motion is unique. This result is used to show that the threshold property of static friction is not a mechanism for hysteresis in rocks. The coda for the surface motion is shown, in the case of a single fracture and a deep source of finite duration, to be either a periodic function in time, or to asymptote in time to such a function, depending on an algebraic relation between ground and fracture parameters. The fundamental period of the coda is independent of the source time series and is equal to four times the signal transit time between the single fracture and ground surface. Only odd harmonics of the fundamental frequency are present in a Fourier series of these periodic functions. {copyright} {ital 1999 Acoustical Society of America.}

  17. Magnetic hysteresis loss and corrosion behavior of LaFe11.5Si1.5 particles coated with Cu

    NASA Astrophysics Data System (ADS)

    Tian, N.; Zhang, N. N.; You, C. Y.; Gao, B.; He, J.

    2013-03-01

    The existence of porosity is useful for releasing the strain during the magnetization and demagnetization processes of La(Fe, Si)13-based magnetocaloric materials, resulting in the decreases of magnetic hysteresis loss and the improvement of mechanical stability. But the porosity would affect the heat transfer and corrosion behavior. In this work, we studied the effect of highly plastic Cu coating on the magnetocaloric properties and corrosion resistance of LaFe11.5Si1.5 particles. It was found that Cu coating had less influence on the magnetic entropy changes, but presented a less magnetic hysteresis loss. Under a maximum field of 1.5 T, both particles with and without coating showed the similar magnetic entropy changes of 8 J/kg K. Magnetic hysteresis loss was decreased from 2.2 to 1.8 J/kg after Cu coating. The corrosion current density was decreased and the corrosion potential was increased, indicating an improvement of the corrosion resistance with Cu coating.

  18. Nonlinear phenomena in fluids with temperature-dependent viscosity: An hysteresis model for magma flow in conduits

    NASA Astrophysics Data System (ADS)

    Costa, Antonio; Macedonio, Giovanni

    2002-05-01

    Magma viscosity is strongly temperature-dependent. When hot magma flows in a conduit, heat is lost through the walls and the temperature decreases along the flow causing a viscosity increase. For particular values of the controlling parameters the steady-flow regime in a conduit shows two stable solutions belonging either to the slow or to the fast branch. As a consequence, this system may show an hysteresis effect, and the transition between the two branches can occur quickly when the critical points are reached. In this paper we describe a model to study the relation between the pressure at the inlet and the volumetric magma flow rate in a conduit. We apply this model to explain an hysteric jump observed during the dome growth at Soufrière Hills volcano (Montserrat), and described by Melnik and Sparks [1999] using a different model.

  19. Plan Showing Cross Bracing Under Upper Stringers, Typical Section Showing ...

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

    Plan Showing Cross Bracing Under Upper Stringers, Typical Section Showing End Framing, Plan Showing Cross Bracing Under Lower Stringers, End Elevation - Covered Bridge, Spanning Contoocook River, Hopkinton, Merrimack County, NH

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  1. Electrostatic curved electrode actuators

    Microsoft Academic Search

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

    1997-01-01

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

  2. Uncertainty propagation: Curve fitting

    NSDL National Science Digital Library

    2013-06-21

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

  3. Parametric Curves Introduction

    E-print Network

    Vickers, James

    in three dimensional space. 9 8 6 7 Prerequisites Before starting this Section you should.3: Parametric Curves 2 #12;i.e. x2 4 + y2 9 = 1 which we easily recognise as an ellipse whose major = 3 sin t together with the parametric range 0 t /2 describe that part of the ellipse x2 4 + y2 9

  4. Straightening Out Learning Curves

    ERIC Educational Resources Information Center

    Corlett, E. N.; Morecombe, V. J.

    1970-01-01

    The basic mathematical theory behind learning curves is explained, together with implications for clerical and industrial training, evaluation of skill development, and prediction of future performance. Brief studies of textile worker and typist training are presented to illustrate such concepts as the reduction fraction (a consistent decrease in…

  5. Characteristic Curves of PEMFC

    NSDL National Science Digital Library

    This in-class exercise will allow students hands-on experience working with a proton exchange membrane fuel cell, or PEMFC. The class will examine the characteristic curve of one of these fuel cells and measure the voltage and current output of the cell. Step by step instructions are provided for the experiment. This document may be downloaded in PDF file format.

  6. Curve Fit Challenge

    ERIC Educational Resources Information Center

    Harper, Suzanne R.; Driskell, Shannon

    2005-01-01

    Graphic tips for using the Geometer's Sketchpad (GSP) are described. The methods to import an image into GSP, define a coordinate system, plot points and curve fit the function using a graphical calculator are demonstrated where the graphic features of GSP allow teachers to expand the use of the technology application beyond the classroom.

  7. Symbolic Parametrization of Curves

    Microsoft Academic Search

    J. Rafael Sendra; Franz Winkler

    1991-01-01

    If algebraic varieties like curves or surfaces are to be manipulated by computers, it is essential to be able to represent these geometric objects in an appropriate way. For some applications an implicit representation by algebraic equations is desirable, whereas for others an explicit or parametric representation is more suitable. Therefore, transformation algorithms from one representation to the other are

  8. Fatigue Hysteresis of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2015-05-01

    When the fiber-reinforced ceramic-matrix composites (CMCs) are first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. Under fatigue loading, the stress-strain hysteresis loops appear as fiber slipping relative to matrix in the interface debonded region upon unloading/reloading. Due to interface wear at room temperature or interface oxidation at elevated temperature, the interface shear stress degredes with increase of the number of applied cycles, leading to the evolution of the shape, location and area of stress-strain hysteresis loops. The evolution characteristics of fatigue hysteresis loss energy in different types of fiber-reinforced CMCs, i.e., unidirectional, cross-ply, 2D and 2.5D woven, have been investigated. The relationships between the fatigue hysteresis loss energy, stress-strain hysteresis loops, interface frictional slip, interface shear stress and interface radial thermal residual stress, matrix stochastic cracking and fatigue peak stress of fiber-reinforced CMCs have been established.

  9. Theory of sorption hysteresis in nanoporous solids: Part II Molecular condensation

    NASA Astrophysics Data System (ADS)

    Bazant, Martin Z.; Bažant, Zden?k P.

    2012-09-01

    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 hysteresis to hindered molecular condensation with attractive lateral interactions. The classical mean-field theory of van der Waals is applied to predict the dependence of hysteresis on temperature and pore size, using the regular solution model and gradient energy of Cahn and Hilliard. A simple "hierarchical wetting" model for thin nanopores is developed to describe the case of strong wetting by the first monolayer, followed by condensation of nanodroplets and nanobubbles in the bulk. The model predicts a larger hysteresis critical temperature and enhanced hysteresis for molecular condensation across nanopores at high vapor pressure than within monolayers at low vapor pressure. For heterogeneous pores, the theory predicts sorption/desorption sequences similar to those seen in molecular dynamics simulations, where the interfacial energy (or gradient penalty) at nanopore junctions acts as a free energy barrier for snap-through instabilities. The model helps to quantitatively understand recent experimental data for concrete or cement paste wetting and drying cycles and suggests new experiments at different temperatures and humidity sweep rates.

  10. Basaltic sand ripples at Eagle Crater as indirect evidence for the hysteresis effect in martian saltation

    NASA Astrophysics Data System (ADS)

    Yizhaq, H.; Kok, J. F.; Katra, I.

    2014-02-01

    The rover Opportunity documented small basaltic sand ripples at the bottom of Eagle Crater, Meridiani Planum on Mars. These ripples are composed of fine basaltic sand (˜100 ?m diameter) and their average wavelength and height are 10 cm and 1 cm, respectively. Present theories on the transition between saltation and suspension predict that such light particles are suspended by turbulence at the fluid threshold, which is the minimum wind speed required to initiate saltation. Consequently, the existence of these ˜100 ?m ripples on Mars indicates that either current suspension theories are incorrect, or that saltation can take place at wind speeds substantially below the fluid threshold. Indeed, recent studies point to the occurrence of hysteresis in martian saltation. That is, once initiated, hysteresis can be maintained at much lower wind speeds than the fluid threshold. We investigated the possible role of hysteresis in the formation of fine-grained ripples on Mars by coupling, for the first time, a detailed numerical saltation model (COMSALT) with a dynamic model for sand ripple formation. The results from the coupled model indicate that ripples with properties similar to those observed at Eagle Crater can be developed by the impact mechanism at shear velocities far below the fluid threshold. These findings are consistent with the occurrence of hysteresis in martian saltation, and support the hypothesis that hysteresis plays a role in the surprisingly large sand mobility observed at several locations on Mars.

  11. New Binary Systems With Asymmetric Light Curves

    NASA Astrophysics Data System (ADS)

    Virnina, Natalia A.

    2010-12-01

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

  12. Dynamic Stability of Curved Panels with Cutouts

    NASA Astrophysics Data System (ADS)

    SAHU, S. K.; DATTA, P. K.

    2002-04-01

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

  13. Roanoke Area Junior Livestock Show

    E-print Network

    Liskiewicz, Maciej

    & Computations Tom Stanley, Chairman Tyler Painter Beth Hawse Katherine Carter Ribbons & Record Keeping Carolyn Supper at Arena 6:00 PM Hog Show: Showmanship, Market Hog Show and Breeding Gilt Show 7:00 pm Check

  14. Development of an analytic key curve approach to drop tower J-R curve measurement

    SciTech Connect

    Joyce, J.A.; Hackett, E.M.

    1986-12-01

    The report describes the development of a dramatically improved method for evaluating J-R curves from 3 point bend specimens tested in a drop tower at loading rates of 2.5 m/second. Aluminum absorbers are used to eliminate the initial transient shock and produce data records smooth enough for direct application of key curve methods. An analytic key curve method is used which eliminates the need for tests on blunt notched or subsize specimens allowing development of a J-R curve for each specimen tested. Results are presented on an A533B steel showing the resulting J-R curve elevation as a function of test rate in comparison with standard static tests.

  15. Perpendicular magnetic anisotropy and rotational hysteresis loss in Co-Cr films

    NASA Astrophysics Data System (ADS)

    Song, I. M.; Ishio, S.; Ishizuka, M.; Tsunoda, T.; Takahashi, M.

    1993-02-01

    Magnetic properties (Curie temperature, magnetization, magnetic anisotropy and rotational hysteresis loss) of Co 100- xCr x films (18 ? x ? 22) and bulk alloys (0 ? × ? 24) were measured to make clear the origin of the perpendicular magnetic anisotropy in Co-Cr films. The magnetization, magnetic anisotropy and rotational hysteresis loss in films are discussed by taking account of the dispersion of the magnetic anisotropy due to a microscopic compositional inhomogeneity. The rotational hysteresis loss of bubble materials such as YFeO 3 and Sm 0.4Y 2.6Fe 3.8Ga 1.2O 12 are also investigated and compared with that of the Co-Cr film.

  16. Diminution of contact angle hysteresis under the influence of an oscillating force.

    PubMed

    Manor, Ofer

    2014-06-17

    We suggest a simple quantitative model for the diminution of contact angle hysteresis under the influence of an oscillatory force invoked by thermal fluctuations, substrate vibrations, acoustic waves, or oscillating electric fields. Employing force balance rather than the usual description of contact angle hysteresis in terms of Gibbs energy, we highlight that a wetting system, such as a sessile drop or a bubble adhered to a solid substrate, appears at long times to be partially or fully independent of contact angle hysteresis and thus independent of static friction forces, as a result of contact line pinning. We verify this theory by studying several well-known experimental observations such as the approach of an arbitrary contact angle toward the Young contact angle and the apparent decrease (or increase) in an advancing (or a receding) contact angle under the influence of an external oscillating force. PMID:24856418

  17. A Model for Rate-Dependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.; Ounaies, Zoubeida; Wieman, Robert

    2001-01-01

    This paper addresses the modeling of certain rate-dependent mechanisms which contribute to hysteresis inherent to piezoelectric materials operating at low frequencies. While quasistatic models are suitable for initial material characterization in some applications, the reduction in coercive field and polarization values which occur as frequencies increase must be accommodated to achieve the full capabilities of the materials. The model employed here quantifies the hysteresis in two steps. In the first, anhysteretic polarization switching is modeled through the application of Boltzmann principles to balance the electrostatic and thermal energy. Hysteresis is then incorporated through the quantification of energy required to translate and bend domain walls pinned at inclusions inherent to the materials. The performance of the model is illustrated through a fit to low frequency data (0.1 Hz - 1 Hz) from a PZT5A wafer.

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

    SciTech Connect

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

    2008-10-14

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

  19. A lumped mucosal wave model of the vocal folds revisited: Recent extensions and oscillation hysteresis

    PubMed Central

    Lucero, Jorge C.; Koenig, Laura L.; Lourenço, Kelem G.; Ruty, Nicolas; Pelorson, Xavier

    2011-01-01

    This paper examines an updated version of a lumped mucosal wave model of the vocal fold oscillation during phonation. Threshold values of the subglottal pressure and the mean (DC) glottal airflow for the oscillation onset are determined. Depending on the nonlinear characteristics of the model, an oscillation hysteresis phenomenon may occur, with different values for the oscillation onset and offset threshold. The threshold values depend on the oscillation frequency, but the occurrence of the hysteresis is independent of it. The results are tested against pressure data collected from a mechanical replica of the vocal folds, and oral airflow data collected from speakers producing intervocalic ?h?. In the human speech data, observed differences between voice onset and offset may be attributed to variations in voice pitch, with a very small or inexistent hysteresis phenomenon. PMID:21428520

  20. Hysteresis between coral reef calcification and the seawater aragonite saturation state

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    PubMed

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

    2006-04-01

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

  2. Incorporation of the capillary hysteresis model HYSTR into the numerical code TOUGH

    SciTech Connect

    Niemi, A.; Bodvarsson, G.S.; Pruess, K.

    1991-11-01

    As part of the work performed to model flow in the unsaturated zone at Yucca Mountain Nevada, a capillary hysteresis model has been developed. The computer program HYSTR has been developed to compute the hysteretic capillary pressure -- liquid saturation relationship through interpolation of tabulated data. The code can be easily incorporated into any numerical unsaturated flow simulator. A complete description of HYSTR, including a brief summary of the previous hysteresis literature, detailed description of the program, and instructions for its incorporation into a numerical simulator are given in the HYSTR user`s manual (Niemi and Bodvarsson, 1991a). This report describes the incorporation of HYSTR into the numerical code TOUGH (Transport of Unsaturated Groundwater and Heat; Pruess, 1986). The changes made and procedures for the use of TOUGH for hysteresis modeling are documented.

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

    SciTech Connect

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

    2013-02-11

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

  4. 6. VIEW SHOWING DOWNSTREAM FACE OF DAM, SHOWING SEEPAGE CONTROL ...

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

    6. VIEW SHOWING DOWNSTREAM FACE OF DAM, SHOWING SEEPAGE CONTROL REINFORCEMENT, LOOKING SOUTHWEST - High Mountain Dams in Upalco Unit, East Timothy Lake Dam, Ashley National Forest, 8.4 miles North of Swift Creek Campground, Mountain Home, Duchesne County, UT

  5. 10. INTERIOR VIEW SHOWING MOUNTINGS FROM TUNING DEVICE. VIEW SHOWS ...

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

    10. INTERIOR VIEW SHOWING MOUNTINGS FROM TUNING DEVICE. VIEW SHOWS COPPER SHEETING ON WALLS. - Chollas Heights Naval Radio Transmitting Facility, Helix House, 6410 Zero Road, San Diego, San Diego County, CA

  6. Trishear for curved faults

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. P.

    2013-08-01

    Fault-propagation folds form an important trapping element in both onshore and offshore fold-thrust belts, and as such benefit from reliable interpretation. Building an accurate geologic interpretation of such structures requires palinspastic restorations, which are made more challenging by the interplay between folding and faulting. Trishear (Erslev, 1991; Allmendinger, 1998) is a useful tool to unravel this relationship kinematically, but is limited by a restriction to planar fault geometries, or at least planar fault segments. Here, new methods are presented for trishear along continuously curved reverse faults defining a flat-ramp transition. In these methods, rotation of the hanging wall above a curved fault is coupled to translation along a horizontal detachment. Including hanging wall rotation allows for investigation of structures with progressive backlimb rotation. Application of the new algorithms are shown for two fault-propagation fold structures: the Turner Valley Anticline in Southwestern Alberta, and the Alpha Structure in the Niger Delta.

  7. On the origin of giant magnetocaloric effect and thermal hysteresis in multifunctional ?-FeRh thin films

    NASA Astrophysics Data System (ADS)

    Zhou, Tiejun; Cher, M. K.; Shen, L.; Hu, J. F.; Yuan, Z. M.

    2013-12-01

    We report temperature and field dependent lattice structure, magnetic properties and magnetocaloric effect in epitaxial Fe50Rh50 thin films with (001) texture. Temperature-dependent XRD measurements reveal an irreversible first-order phase transition with 0.66% lattice change upon heating/cooling. First-principle calculation shows a state change of Rh from non-magnetic (0 ?B) for antiferromagnetic phase to magnetic (0.93 ?B) state for ferromagnetic phase. A jump of magnetization at temperature of 305 K and field more than 5 T indicates a field-assisted magnetic state change of Ru that contributes to the jump. Giant positive magnetic entropy change was confirmed by isothermal magnetization measurements and an in-situ temperature rise of 15 K. The magnetic state change of Rh between antiferromagnetic and ferromagnetic states is the main origin of giant magnetic entropy change and large thermal hysteresis observed.

  8. Inducing chaos in a gene regulatory network by coupling an oscillating dynamics with a hysteresis-type one.

    PubMed

    Poignard, Camille

    2014-08-01

    In this paper, we investigate the chaotic behavior of a gene regulatory network modeled by four differential equations and seventeen parameters. This network, called [Formula: see text]-system, has been designed to couple in a simple way an oscillating system with one having a bistable switch. After having studied it analytically, we exhibit (by a constructive proof) the mechanism responsible of chaos for a general differential system presenting such a coupling. Namely, given a generic one-parameter family of smooth vector fields on [Formula: see text] presenting a Hopf bifurcation, we prove that under an assumption on the Jacobian at the bifurcation point, we can create such a chaotic system by perturbing the parameter thanks to a hysteresis-type dynamics. Finally, we numerically show that the mechanism highlighted previously takes place in the [Formula: see text]-system, for a particular set of values of its parameters. PMID:23842815

  9. Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability.

    PubMed

    Hu, Aixue; Meehl, Gerald A; Han, Weiqing; Timmermann, Axel; Otto-Bliesner, Bette; Liu, Zhengyu; Washington, Warren M; Large, William; Abe-Ouchi, Ayako; Kimoto, Masahide; Lambeck, Kurt; Wu, Bingyi

    2012-04-24

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80-11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art 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 ocean conveyor belt circulation 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. PMID:22493225

  10. Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

    PubMed Central

    Hu, Aixue; Meehl, Gerald A.; Han, Weiqing; Timmermann, Axel; Otto-Bliesner, Bette; Liu, Zhengyu; Washington, Warren M.; Large, William; Abe-Ouchi, Ayako; Kimoto, Masahide; Lambeck, Kurt; Wu, Bingyi

    2012-01-01

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80–11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art 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 ocean conveyor belt circulation 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. PMID:22493225

  11. Anatomical curve identification

    PubMed Central

    Bowman, Adrian W.; Katina, Stanislav; Smith, Joanna; Brown, Denise

    2015-01-01

    Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest. PMID:26041943

  12. Curved PN triangles

    Microsoft Academic Search

    Alex Vlachos; Jörg Peters; Chas Boyd; Jason L. Mitchell

    2001-01-01

    To improve the visual quality of existing triangle-based art in real- time entertainment, such as computer games, we propose replacing flat triangles with curved patches and higher-order normal variation. At the hardware level, based only on the three vertices and three vertex normals of a given flat triangle, we substitute the geometry of a three-sided cubic Bezier patch for the

  13. Diffusion in Curved Spacetimes

    E-print Network

    Matteo Smerlak

    2011-11-18

    Using simple kinematical arguments, we derive the Fokker-Planck equation for diffusion processes in curved spacetimes. In the case of Brownian motion, it coincides with Eckart's relativistic heat equation (albeit in a simpler form), and therefore provides a microscopic justification for his phenomenological heat-flux ansatz. Furthermore, we obtain the small-time asymptotic expansion of the mean square displacement of Brownian motion in static spacetimes. Beyond general relativity itself, this result has potential applications in analogue gravitational systems.

  14. Brody curves omitting hyperplanes

    E-print Network

    For the recent work on Brody curves we refer to [3, 10, 11, 12, 13]. A. general reference .... We are going to prove first that. u0(z) ? u?(z) + 4(n + 1)|z| sup. C. f . (5). 4 ... On the other hand, |f0(z1)| = |fk(z1)|?|fj(z1)| for all j ? {1,...,n}, so. f (z1) ?

  15. Interplay between order-parameter and system parameter dynamics: considerations on perceptual-cognitive-behavioral mode-mode transitions exhibiting positive and negative hysteresis and on response times.

    PubMed

    Frank, T D; Profeta, V L S; Harrison, H S

    2015-06-01

    A mathematical model is presented for the emergence of perceptual-cognitive-behavioral modes in psychophysical experiments in which participants are confronted with two alternatives. The model is based on the theory of self-organization and, in particular, the order parameter concept such that the emergence of a mode is conceptualized as an instability leading to the emergence of an appropriately defined order parameter. The order parameter model is merged with a second model that describes adaptation in terms of a system parameter dynamics. It is shown that the two-component model predicts hysteretic mode-mode transitions when control parameters are increased or decreased beyond critical values. The two-component model can account for both positive and negative hysteresis effects due to the interaction between order parameter and system parameter dynamics. Moreover, the model-based analysis reveals that response time curves look rather flat when response times are relatively decoupled from the mode-mode transition phenomenon. In general, response time curves exhibit a peaked close to the mode-mode transition point. In this context, the possibility is discussed that such peaked response time curves belong to the class of critical phenomena of self-organizing systems. In order to illustrate the relevance of peaked response time curves for future research and research reported in the past, results from a perceptual judgment experiment are reported, in which participants judged their ability to stand on a tilted slope for various angles of inclination. Response time curves were found that exhibited a peak around the mode-mode-transition points between "yes" and "no" responses. PMID:25727808

  16. Quantization on Curves

    NASA Astrophysics Data System (ADS)

    Frønsdal, Christian; Kontsevich, Maxim

    2007-02-01

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

  17. Electric field induced fluorescence hysteresis of single molecules in poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Zhou, Haitao; Qin, Chengbing; Chen, Ruiyun; Zhang, Guofeng; Xiao, Liantuan; Jia, Suotang

    2014-10-01

    Single molecule (SM) chips could serve as the fundamental devices in quantum information processing. In this context, a chip with the non-polar SMs of squaraine-derived rotaxanes embedded in a polar poly(methyl methacrylate) matrix was realized and the SM fluorescence hysteresis induced by the electric field was observed at room temperature. Here, we presented a model considering both of the electron transfer and space charge relaxation processes to explain the fluorescence hysteresis effect, and the model-based simulations agreed reasonably well with the experimental results.

  18. Hysteresis effects in instantaneous frequency scaling of attenuation on 20 and 30 GHz satellite links

    NASA Technical Reports Server (NTRS)

    Sweeney, D. G.; Pratt, T.; Bostian, C. W.

    1992-01-01

    It has been observed with 20/30 GHz satellite beacon measurements that the ratio of 30 GHz to 20 GHz attenuation changes during some fade events. This ratio displays a hysteresis effect. This effect can be explained by a change in the drop size distribution (DSD) during the event. However, it appears only above approximately 6-8 dB of attenuation at 20 GHz. Instantaneous frequency scaling of attenuation is being proposed as part of an algorithm for uplink power control (ULPC) and the dynamic range of such an algorithm must be appropriately limited to avoid the hysteresis.

  19. Hysteresis during field emission from chemical vapor deposition synthesized carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Cahay, M.; Murray, P. T.; Back, T. C.; Fairchild, S.; Boeckl, J.; Bulmer, J.; Koziol, K. K. K.; Gruen, G.; Sparkes, M.; Orozco, F.; O'Neill, W.

    2014-10-01

    Hysteresis in the field emission (FE) data of a chemical vapor synthesized carbon nanotube fiber cathode is analyzed in the regime where self-heating effects are negligible. In both the forward and reverse applied field sweeps, various FE modes of operation are identified: including Fowler-Nordheim (FN) tunneling and space-charge limited emission from the fiber tip and FN emission from the fiber sidewall. Hysteresis in the FE data is linked to the difference in the field enhancement factors in the different FE modes of operation in the forward and reverse sweeps and related to changes in the fiber morphology.

  20. New formulation of the Stoner-Wohlfarth hysteresis model and the identification problem

    NASA Astrophysics Data System (ADS)

    Friedman, G.

    1990-05-01

    A new formulation of the Stoner-Wohlfarth hysteresis model is introduced. This formulation simplifies the analysis of the model through the use of a diagram technique similar to the one employed by the Preisach model. It is shown that using the new formulation the identification problem can be posed in terms of an integral equation relating the switching field distribution to the set of vertical chords of symmetric minor hysteresis loops. Solution of this integral equation is discussed, and some limitations of the Stoner-Wohlfarth model are revealed.

  1. Landau Theory of Phase Transition in Ferroelectric Vinylidene Fluoride/Trifluoroethylene Copolymer Single Crystals: Hysteresis Loop

    NASA Astrophysics Data System (ADS)

    Iwata, Makoto; Ishibashi, Yoshihiro

    2005-09-01

    Ferroelectric hysteresis loops in vinylidene fluoride/trifluoroethylene, P[VDF/TrFE], copolymer single crystals are discussed on the basis of the Landau-type free energy function with the anisotropy parameter ?2. It was found that the coercive field strongly depends on the value of ?2, and decreases as ?2=0 is approached, because the Landau-type free energy function becomes isotropic in the order parameter space. We successfully reproduced the p-E hysteresis loop with a square shape and a small coercive field in P[VDF/TrFE] on the basis of the Landau theory with the anisotropy parameter ?2.

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

    SciTech Connect

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

    2009-10-09

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

  3. Stability Limits of Capillary Bridges: How Contact Angle Hysteresis Affects Morphology Transitions of Liquid Microstructures

    NASA Astrophysics Data System (ADS)

    de Ruiter, Riëlle; Semprebon, Ciro; van Gorcum, Mathijs; Duits, Michèl H. G.; Brinkmann, Martin; Mugele, Frieder

    2015-06-01

    The equilibrium shape of a drop in contact with solid surfaces can undergo continuous or discontinuous transitions upon changes in either drop volume or surface energies. In many instances, such transitions involve the motion of the three-phase contact line and are thus sensitive to contact angle hysteresis. Using a combination of electrowetting-based experiments and numerical calculations, we demonstrate for a generic sphere-plate confinement geometry how contact angle hysteresis affects the mechanical stability of competing axisymmetric and nonaxisymmetric drop conformations and qualitatively changes the character of transitions between them.

  4. Distinguishing magnetic particle size of iron oxide nanoparticles with first-order reversal curves

    SciTech Connect

    Kumari, Monika; Hirt, Ann M., E-mail: ann.hirt@erdw.ethz.ch [Department of Earth Sciences, Institute of Geophysics, ETH-Zurich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland); Widdrat, Marc; Faivre, Damien [Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, D-14424 Potsdam (Germany); Tompa, Éva; Pósfai, Mihály [Department of Earth and Environmental Sciences, University of Pannonia, Egyetem u. 10, H-8200 Veszprém (Hungary); Uebe, Rene; Schüler, Dirk [Department Biologie I, LMU Munich, Großhaderner Str. 2, D-82152 Martinsried (Germany)

    2014-09-28

    Magnetic nanoparticles encompass a wide range of scientific study and technological applications. The success of using the nanoparticles in various applications demands control over size, dispersibility, and magnetics. Hence, the nanoparticles are often characterized by transmission electron microscopy (TEM), X-ray diffraction, and magnetic hysteresis loops. TEM analysis requires a thin layer of dispersed particles on the grid, which may often lead to particle aggregation thus making size analysis difficult. Magnetic hysteresis loops on the other hand provide information on the bulk property of the material without discriminating size, composition, and interaction effects. First order reversal curves (FORCs), described as an assembly of partial hysteresis loops originating from the major loop are efficient in identifying the domain size, composition, and interaction in a magnetic system. This study presents FORC diagrams on a variety of well-characterized biogenic and synthetic magnetite nanoparticles. It also introduces deconvoluted reversible and irreversible components from FORC as an important method for obtaining a semi-quantitative measure of the effective magnetic particle size. This is particularly important in a system with aggregation and interaction among the particles that often leads to either the differences between physical size and effective magnetic size. We also emphasize the extraction of secondary components by masking dominant coercivity fraction on FORC diagram to explore more detailed characterization of nanoparticle systems.

  5. Punishment in public goods games leads to meta-stable phase transitions and hysteresis

    NASA Astrophysics Data System (ADS)

    Hintze, Arend; Adami, Christoph

    2015-07-01

    The evolution of cooperation has been a perennial problem in evolutionary biology because cooperation can be undermined by selfish cheaters who gain an advantage in the short run, while compromising the long-term viability of the population. Evolutionary game theory has shown that under certain conditions, cooperation nonetheless evolves stably, for example if players have the opportunity to punish cheaters that benefit from a public good yet refuse to pay into the common pool. However, punishment has remained enigmatic because it is costly and difficult to maintain. On the other hand, cooperation emerges naturally in the public goods game if the synergy of the public good (the factor multiplying the public good investment) is sufficiently high. In terms of this synergy parameter, the transition from defection to cooperation can be viewed as a phase transition with the synergy as the critical parameter. We show here that punishment reduces the critical value at which cooperation occurs, but also creates the possibility of meta-stable phase transitions, where populations can ‘tunnel’ into the cooperating phase below the critical value. At the same time, cooperating populations are unstable even above the critical value, because a group of defectors that are large enough can ‘nucleate’ such a transition. We study the mean-field theoretical predictions via agent-based simulations of finite populations using an evolutionary approach where the decisions to cooperate or to punish are encoded genetically in terms of evolvable probabilities. We recover the theoretical predictions and demonstrate that the population shows hysteresis, as expected in systems that exhibit super-heating and super-cooling. We conclude that punishment can stabilize populations of cooperators below the critical point, but it is a two-edged sword: it can also stabilize defectors above the critical point.

  6. Punishment in public goods games leads to meta-stable phase transitions and hysteresis.

    PubMed

    Hintze, Arend; Adami, Christoph

    2015-01-01

    The evolution of cooperation has been a perennial problem in evolutionary biology because cooperation can be undermined by selfish cheaters who gain an advantage in the short run, while compromising the long-term viability of the population. Evolutionary game theory has shown that under certain conditions, cooperation nonetheless evolves stably, for example if players have the opportunity to punish cheaters that benefit from a public good yet refuse to pay into the common pool. However, punishment has remained enigmatic because it is costly and difficult to maintain. On the other hand, cooperation emerges naturally in the public goods game if the synergy of the public good (the factor multiplying the public good investment) is sufficiently high. In terms of this synergy parameter, the transition from defection to cooperation can be viewed as a phase transition with the synergy as the critical parameter. We show here that punishment reduces the critical value at which cooperation occurs, but also creates the possibility of meta-stable phase transitions, where populations can 'tunnel' into the cooperating phase below the critical value. At the same time, cooperating populations are unstable even above the critical value, because a group of defectors that are large enough can 'nucleate' such a transition. We study the mean-field theoretical predictions via agent-based simulations of finite populations using an evolutionary approach where the decisions to cooperate or to punish are encoded genetically in terms of evolvable probabilities. We recover the theoretical predictions and demonstrate that the population shows hysteresis, as expected in systems that exhibit super-heating and super-cooling. We conclude that punishment can stabilize populations of cooperators below the critical point, but it is a two-edged sword: it can also stabilize defectors above the critical point. PMID:26031571

  7. Curve-centric volume reformation for comparative visualization.

    PubMed

    Daae Lampe, Ove; Correa, Carlos; Ma, Kwan-Liu; Hauser, Helwig

    2009-01-01

    We present two visualization techniques for curve-centric volume reformation with the aim to create compelling comparative visualizations. A curve-centric volume reformation deforms a volume, with regards to a curve in space, to create a new space in which the curve evaluates to zero in two dimensions and spans its arc-length in the third. The volume surrounding the curve is deformed such that spatial neighborhood to the curve is preserved. The result of the curve-centric reformation produces images where one axis is aligned to arc-length, and thus allows researchers and practitioners to apply their arc-length parameterized data visualizations in parallel for comparison. Furthermore we show that when visualizing dense data, our technique provides an inside out projection, from the curve and out into the volume, which allows for inspection what is around the curve. Finally we demonstrate the usefulness of our techniques in the context of two application cases. We show that existing data visualizations of arc-length parameterized data can be enhanced by using our techniques, in addition to creating a new view and perspective on volumetric data around curves. Additionally we show how volumetric data can be brought into plotting environments that allow precise readouts. In the first case we inspect streamlines in a flow field around a car, and in the second we inspect seismic volumes and well logs from drilling. PMID:19834194

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

    Microsoft Academic Search

    B. K. Bose

    1990-01-01

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

  9. Recoverable Residual Image Induced by Hysteresis of Thin Film Transistors in Active Matrix Organic Light Emitting Diode Displays

    Microsoft Academic Search

    Byeong-Koo Kim; Ohyun Kim; Hoon-Ju Chung; Jae-Won Chang; Yong-Min Ha

    2004-01-01

    A recoverable residual image is observed and analyzed in voltage driven active matrix organic light emitting diode (AMOLED) displays of which pixel circuits consist of two thin film transistors (TFTs) and one capacitor. The cause of the residual image is proven to be the hysteresis of the driving TFT in the pixel. The hysteresis of the p-channel TFT can be

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  11. What Do Blood Tests Show?

    MedlinePLUS

    ... page from the NHLBI on Twitter. What Do Blood Tests Show? Blood tests show whether the levels ... changes may work best. Result Ranges for Common Blood Tests This section presents the result ranges for ...

  12. Asia: Showing the Changing Seasons

    NSDL National Science Digital Library

    Jesse Allen

    1998-09-09

    SeaWiFS false color data showing seasonal change in the oceans and on land for Asia. The data is seasonally averaged, and shows the sequence: fall, winter, spring, summer, fall, winter, spring (for the Northern Hemisphere).

  13. On planar rational cuspidal curves

    E-print Network

    Liu, Tiankai

    2014-01-01

    This thesis studies rational curves in the complex projective plane that are homeomorphic to their normalizations. We derive some combinatorial constraints on such curves from a result of Borodzik-Livingston in Heegaard-Floer ...

  14. New explicit conditions of elliptic curve traces for FR-reduction

    Microsoft Academic Search

    Atsuko MIYAJI; Masaki NAKABAYASHI; Shunzou TAKANO

    2001-01-01

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

  15. Moisture-induced hysteresis of pentacene thin film transistors with cross-linked poly(4-vinylphenol) gate dielectrics.

    PubMed

    Kim, Jun Ho; Beak, Kyu-Ha; Song, Ki Chul; Kim, Do Jin; Lee, Kijun; Do, Lee-Mi

    2011-05-01

    The time variable electrical characteristics of pentacene thin-film transistors (TFTs) with poly(4-vinylphenol) gate dielectrics were investigated under various relative humidity conditions and the effect of moisture on the hysteresis behavior of the pentacene TFTs was studied. One possible cause of the hysteresis behavior is the presence of inherent hydroxyl groups in bulk or surface of the polymeric dielectric, which make the gate dielectric polar, but the hysteresis behavior of the pentacene TFTs was found to depend strongly on the relative humidity and to increase with an increase of the moisture in the surrounding atmosphere. With a time-scalable investigation, it was also found that the adsorption of moisture onto the pentacene layer is the main reason for the hysteresis even with the -OH rich polymeric dielectric. The hysteresis behavior was found to be significantly reduced by suppression of moisture or other moisture-induced impurities, such as the encapsulation of the devices with glass. PMID:21780500

  16. Titration Curves: Fact and Fiction.

    ERIC Educational Resources Information Center

    Chamberlain, John

    1997-01-01

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

  17. Dragon curves revisited S. Tabachnikov

    E-print Network

    Tabachnikov, Sergei

    Dragon curves revisited S. Tabachnikov It has happened several times in recent history mathematical object of comparable beauty, the Dragon curves, whose theory was created by Chandler Davis with previously unpublished addendum).1 Mathematical Intelligencer wrote about Dragon curves more than 30 years

  18. Guide to Elliptic Curve Cryptography

    E-print Network

    Babinkostova, Liljana

    Guide to Elliptic Curve Cryptography Darrel Hankerson Alfred Menezes Scott Vanstone Springer #12;Guide to Elliptic Curve Cryptography Springer New York Berlin Heidelberg Hong Kong London Milan Paris Tokyo #12;#12;Darrel Hankerson Alfred Menezes Scott Vanstone Guide to Elliptic Curve Cryptography

  19. Modeling the Keeling Curve

    NSDL National Science Digital Library

    In this problem set, learners will refer to the tabulated data used to create the Keeling Curve of atmospheric carbon dioxide to create a mathematical function that accounts for both periodic and long-term changes. They will use this function to answer a series of questions, including predictions of atmospheric concentration in the future. A link to the data, which is in an Excel file, as well as the answer key are provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

  20. 1. Show the synthesis of prontosil. Show the starting

    E-print Network

    Gates, Kent. S.

    how the three analogs shown below can be prepared. Draw an arrow-pushing mechanism for each step is not active in an in vitro assay, but shows good activity in animal models and human patients. Explain: what

  1. Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems

    NASA Astrophysics Data System (ADS)

    Duclut, Charlie; Backhaus, Scott; Chertkov, Michael

    2013-06-01

    The majority of dynamical studies in power systems focus on the high-voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to the outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatiotemporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially extended phases defined by individual motor states, a “normal” state where the motors’ mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a “stalled” state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors’ mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases.

  2. Hysteresis of Soil Point Water Retention Functions Determined by Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Perfect, E.; Kang, M.; Bilheux, H.; Willis, K. J.; Horita, J.; Warren, J.; Cheng, C.

    2010-12-01

    Soil point water retention functions are needed for modeling flow and transport in partially-saturated porous media. Such functions are usually determined by inverse modeling of average water retention data measured experimentally on columns of finite length. However, the resulting functions are subject to the appropriateness of the chosen model, as well as the initial and boundary condition assumptions employed. Soil point water retention functions are rarely measured directly and when they are the focus is invariably on the main drying branch. Previous direct measurement methods include time domain reflectometry and gamma beam attenuation. Here we report direct measurements of the main wetting and drying branches of the point water retention function using neutron radiography. The measurements were performed on a coarse sand (Flint #13) packed into 2.6 cm diameter x 4 cm long aluminum cylinders at the NIST BT-2 (50 ?m resolution) and ORNL-HFIR CG1D (70 ?m resolution) imaging beamlines. The sand columns were saturated with water and then drained and rewetted under quasi-equilibrium conditions using a hanging water column setup. 2048 x 2048 pixel images of the transmitted flux of neutrons through the column were acquired at each imposed suction (~10-15 suction values per experiment). Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert’s law in conjunction with beam hardening and geometric corrections. The pixel rows were averaged and combined with information on the known distribution of suctions within the column to give 2048 point drying and wetting functions for each experiment. The point functions exhibited pronounced hysteresis and varied with column height, possibly due to differences in porosity caused by the packing procedure employed. Predicted point functions, extracted from the hanging water column volumetric data using the TrueCell inverse modeling procedure, showed very good agreement with the range of point functions measured within the column using neutron radiography. Extension of these experiments to 3-dimensions using neutron tomography is planned.

  3. Torpor and hypothermia: reversed hysteresis of metabolic rate and body temperature.

    PubMed

    Geiser, Fritz; Currie, Shannon E; O'Shea, Kelly A; Hiebert, Sara M

    2014-12-01

    Regulated torpor and unregulated hypothermia are both characterized by substantially reduced body temperature (Tb) and metabolic rate (MR), but they differ physiologically. Although the remarkable, medically interesting adaptations accompanying torpor (e.g., tolerance for cold and ischemia, absence of reperfusion injury, and disuse atrophy) often do not apply to hypothermia in homeothermic species such as humans, the terms "torpor" and "hypothermia" are often used interchangeably in the literature. To determine how these states differ functionally and to provide a reliable diagnostic tool for differentiating between these two physiologically distinct states, we examined the interrelations between Tb and MR in a mammal (Sminthopsis macroura) undergoing a bout of torpor with those of the hypothermic response of a similar-sized juvenile rat (Rattus norvegicus). Our data show that under similar thermal conditions, 1) cooling rates differ substantially (approximately fivefold) between the two states; 2) minimum MR is approximately sevenfold higher during hypothermia than during torpor despite a similar Tb; 3) rapid, endogenously fuelled rewarming occurs in torpor but not hypothermia; and 4) the hysteresis between Tb and MR during warming and cooling proceeds in opposite directions in torpor and hypothermia. We thus demonstrate clear diagnostic physiological differences between these two states that can be used experimentally to confirm whether torpor or hypothermia has occurred. Furthermore, the data can clarify the results of studies investigating the ability of physiological or pharmacological agents to induce torpor. Consequently, we recommend using the terms "torpor" and "hypothermia" in ways that are consistent with the underlying regulatory differences between these two physiological states. PMID:25253085

  4. 3D combinational curves for accuracy and performance analysis of positive biometrics identification

    NASA Astrophysics Data System (ADS)

    Du, Yingzi; Chang, Chein-I.

    2008-06-01

    The receiver operating characteristic (ROC) curve has been widely used as an evaluation criterion to measure the accuracy of biometrics system. Unfortunately, such an ROC curve provides no indication of the optimum threshold and cost function. In this paper, two kinds of 3D combinational curves are proposed: the 3D combinational accuracy curve and the 3D combinational performance curve. The 3D combinational accuracy curve gives a balanced view of the relationships among FAR (false alarm rate), FRR (false rejection rate), threshold t, and Cost. Six 2D curves can be derived from the 3D combinational accuracy curve: the conventional 2D ROC curve, 2D curve of (FRR, t), 2D curve of (FAR, t), 2D curve of (FRR, Cost), 2D curve of (FAR, Cost), and 2D curve of ( t, Cost). The 3D combinational performance curve can be derived from the 3D combinational accuracy curve which can give a balanced view among Security, Convenience, threshold t, and Cost. The advantages of using the proposed 3D combinational curves are demonstrated by iris recognition systems where the experimental results show that the proposed 3D combinational curves can provide more comprehensive information of the system accuracy and performance.

  5. FORWARD HYSTERESIS AND BACKWARD BIFURCATION CAUSED BY CULLING IN AN AVIAN INFLUENZA MODEL

    E-print Network

    Martcheva, Maia

    FORWARD HYSTERESIS AND BACKWARD BIFURCATION CAUSED BY CULLING IN AN AVIAN INFLUENZA MODEL HAYRIYE influenza virus strain magnifies the need for controlling the incidence of H5N1 infection in domestic bird measure. We use mathematical modeling to understand the dynamics of avian influenza under different

  6. A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners

    Microsoft Academic Search

    A. J. Fleming; S. O. R. Moheimani

    2005-01-01

    In this paper, a charge amplifier adapted for piezoelectric tube scanners is presented. Previous problems involved with the implementation of such amplifiers are resolved to provide dc accurate performance with zero voltage drift. In our experiment, hysteresis was reduced by 89% when compared to a voltage amplifier.

  7. A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners

    E-print Network

    Fleming, Andrew J.

    A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners A. J 2005 In this paper, a charge amplifier adapted for piezoelectric tube scanners is presented. Previous Piezoelectric tube scanners were reported by Binnig and Smith1 for use in scanning tunneling microscopes.2

  8. Influence of eddy currents on magnetic hysteresis loops in soft magnetic materials

    Microsoft Academic Search

    Jan Szczyg?owski

    2001-01-01

    In this paper an attempt has been made to extend the Jiles and Atherton (J–A) quasi-static hysteresis model to describe magnetisation of a material with an alternating magnetic field. In low – industrial – and medium frequency of magnetic field it is possible to ignore the magnetic relaxation and resonance. The field penetration is assumed to be uniform through the

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

    Microsoft Academic Search

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

    2011-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wasilewski, P. J.

    1973-01-01

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

  11. Calculation of the magnetic field in the active zone of a hysteresis clutch

    NASA Technical Reports Server (NTRS)

    Ermilov, M. A.; Glukhov, O. M.

    1977-01-01

    The initial distribution of magnetic induction in the armature stationary was calculated relative to the polar system of a hysteresis clutch. Using several assumptions, the problem is reduced to calculating the static magnetic field in the ferromagnetic plate with finite and continuous magnetic permeability placed in the air gap between two identical, parallel semiconductors with rack fixed relative to the tooth or slot position.

  12. Approximate Inversion of the Preisach Hysteresis Operator with Application to Control of Smart

    E-print Network

    Iyer, Ram Venkataraman

    , Magnetostriction, Piezoelectricity, Shape memory alloys, Electro-active polymers, Fixed Point iteration algorithm, and shape memory alloys (SMAs), exhibit strong coupling between applied electromagnetic/thermal fields the hysteresis phenomenon in piezo- electric [5], magnetostrictive materials [6], [7], shape-memory alloys [8

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

    Microsoft Academic Search

    A. Bekker; L. C. Brinson

    1998-01-01

    In this paper, we develop a consistent mathematical description of martensite fraction evolution during athermal thermoelastic phase transformation in a shape memory alloy (SMA) induced by a general thermomechanical loading. The global kinetic law is based on an experimentally defined stress–temperature phase diagram, transformation functions for a one-dimensional SMA body and a novel vector hysteresis model. The global kinetic law

  14. Scaling behavior of hysteresis in multilayer MoS{sub 2} field effect transistors

    SciTech Connect

    Li, Tao; Du, Gang; Zhang, Baoshun; Zeng, Zhongming, E-mail: zmzeng2012@sinano.ac.cn [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123 (China)

    2014-09-01

    Extrinsic hysteresis effects are often observed in MoS{sub 2} field effect devices due to adsorption of gas molecules on the surface of MoS{sub 2} channel. Scaling is a common method used in ferroics to quantitatively study the hysteresis. Here, the scaling behavior of hysteresis in multilayer MoS{sub 2} field effect transistors with a back-gated configuration was investigated. The power-law scaling relations were obtained for hysteresis area (?A?) and memory window (?V) with varying the region of back-gate voltage (V{sub bg,max}). It is interesting to find that the transition voltage in the forward sweep (V{sub FW}) and in the backward sweep (V{sub BW}) shifted to the opposite directions of back-gate voltage (V{sub bg}) with increasing V{sub bg,max}. However, when decreasing V{sub bg,max}, V{sub FW} shifted to positive and reversibly recovered, but V{sub BW} almost kept unchanged. The evolution of ?A?, ?V, V{sub FW,} and V{sub BW} with V{sub bg,max} were discussed by the electrons transferring process between the adsorbate and MoS{sub 2} channel.

  15. A stability-based mechanism for hysteresis in the walk–trot transition in quadruped locomotion

    PubMed Central

    Aoi, Shinya; Katayama, Daiki; Fujiki, Soichiro; Tomita, Nozomi; Funato, Tetsuro; Yamashita, Tsuyoshi; Senda, Kei; Tsuchiya, Kazuo

    2013-01-01

    Quadrupeds vary their gaits in accordance with their locomotion speed. Such gait transitions exhibit hysteresis. However, the underlying mechanism for this hysteresis remains largely unclear. It has been suggested that gaits correspond to attractors in their dynamics and that gait transitions are non-equilibrium phase transitions that are accompanied by a loss in stability. In the present study, we used a robotic platform to investigate the dynamic stability of gaits and to clarify the hysteresis mechanism in the walk–trot transition of quadrupeds. Specifically, we used a quadruped robot as the body mechanical model and an oscillator network for the nervous system model to emulate dynamic locomotion of a quadruped. Experiments using this robot revealed that dynamic interactions among the robot mechanical system, the oscillator network, and the environment generate walk and trot gaits depending on the locomotion speed. In addition, a walk–trot transition that exhibited hysteresis was observed when the locomotion speed was changed. We evaluated the gait changes of the robot by measuring the locomotion of dogs. Furthermore, we investigated the stability structure during the gait transition of the robot by constructing a potential function from the return map of the relative phase of the legs and clarified the physical characteristics inherent to the gait transition in terms of the dynamics. PMID:23389894

  16. Fractal analysis of soil water hysteresis as influenced by sewage sludge application

    E-print Network

    Perfect, Ed

    Fractal analysis of soil water hysteresis as influenced by sewage sludge application G. Ojeda a,, E) and a loamy sand soil (Typic Haplustalf) from central Catalonia (NE Spain) was investigated using fractal analysis. First, we proposed a composite fractal model that covers both the low and high suction regimes

  17. Quantum step heights in hysteresis loops of molecular magnets Roberto B. Diener,1

    E-print Network

    Niu, Qian

    Quantum step heights in hysteresis loops of molecular magnets Jie Liu,1 Biao Wu,1 Libin Fu,2 February 2002; published 16 May 2002 We present an analytical theory on the heights of the quantum steps molecular spins, our theory successfully yields the step heights measured in experiments, and reveals

  18. Materials on the brink: Unprecedented transforming materials www.low-hysteresis.caltech.edu

    E-print Network

    Wuttig (Shenqiang Ren1*) 1 Graduate Student 2 Post-doc · Other/supplemental support + Transitioned #12-change materials Sensing, Actuation, Communications, Energy harvesting and storage But, promise is largely interfaces can reduce hysteresis Nucleation and growth reduces the barrier to structural phase transition

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

    Microsoft Academic Search

    William McMurray

    1984-01-01

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

  20. Effects of flux and torque hysteresis band amplitude in direct torque control of induction machines

    Microsoft Academic Search

    D. Casadei; G. Grandi; G. Serra; A. Tani

    1994-01-01

    Direct torque control of induction machines allows high dynamic performance to be obtained utilising a simple signal processing method. Furthermore, this control technique does not require current regulators so reducing the hardware requirements. In this paper, the influence of the amplitude of flux and torque hysteresis bands on switching frequency, torque and flux ripple, current distortion and drive losses is