Science.gov

Sample records for hysteresis

  1. Hysteresis in weak ferromagnets

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Magnetic hysteresis is studied in the orthoferrites ErFeO3 and TmFeO3 using the single crystal samples of millimeter dimensions. It is shown that in both materials one observes a temperature transition manifesting itself through the temperature hysteresis of the magnetic moment and a peculiar temperature evolution of the field hysteresis loop shapes near this transition. Experiments rule out the hypothesis that the ordering of the orthoferrite's rare earth magnetic moments plays an important role in these phenomena. The hysteresis curves can be explained by a few-domain magnetic state of the samples that results from the weak ferromagnetism of the orthoferrites. The phenomenon is generic for weak ferromagnets with temperature dependent magnetization. A large characteristic magnetic length makes the behavior of the relatively big samples analogous to that observed in the nano-size samples of strong ferromagnets. Supported by NSF DMR-0847159, Ukrainian DFFD F28/456-2009, Portuguese FCT ``Ciencia 2007''.

  2. Mathematical models of hysteresis

    SciTech Connect

    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.

  3. Hysteresis of ionization waves

    SciTech Connect

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

    2008-06-15

    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.

  4. A magnetic hysteresis model

    NASA Technical Reports Server (NTRS)

    Flatley, Thomas W.; Henretty, Debra A.

    1995-01-01

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

  5. Mach, methodology, hysteresis and economics

    NASA Astrophysics Data System (ADS)

    Cross, R.

    2008-11-01

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

  6. Theory of molecular hysteresis switch

    NASA Astrophysics Data System (ADS)

    Kozhushner, Mortko; Oleynik, Ivan

    2006-03-01

    Molecular hysteresis switching has been recently observed in a series of experiments that measured the I-V spectrum of bipyridyl-dinitro oligophenylene-ethylene dithiol (BPDN) based molecular devices [1]. The experimental observations clearly show the presence of Coulomb blockade in single organic molecules that is responsible for the voltage-induced switching. We present the theory of the hysteresis switch which explains the non-linear hysteresis I-V characteristics based on the mechanisms of Coulomb blockade and the existence of two different molecular conformations of neutral and charged states of the molecule. [1] A.S. Blum, J.G. Kushmerick, D.P. Long, C.H. Patterson, J.C. Yang, J.C. Henderson, Y.X. Yao, J.M. Tour, R. Shashidhar, and B.R. Ratna, ``Molecularly inherent voltage-controlled conductance switching'' , Nature Materials 4, 167 (2005).

  7. Wetting hysteresis induced by nanodefects.

    PubMed

    Giacomello, Alberto; Schimmele, Lothar; Dietrich, Siegfried

    2016-01-19

    Wetting of actual surfaces involves diverse hysteretic phenomena stemming from ever-present imperfections. Here, we clarify the origin of wetting hysteresis for a liquid front advancing or receding across an isolated defect of nanometric size. Various kinds of chemical and topographical nanodefects, which represent salient features of actual heterogeneous surfaces, are investigated. The most probable wetting path across surface heterogeneities is identified by combining, within an innovative approach, microscopic classical density functional theory and the string method devised for the study of rare events. The computed rugged free-energy landscape demonstrates that hysteresis emerges as a consequence of metastable pinning of the liquid front at the defects; the barriers for thermally activated defect crossing, the pinning force, and hysteresis are quantified and related to the geometry and chemistry of the defects allowing for the occurrence of nanoscopic effects. The main result of our calculations is that even weak nanoscale defects, which are difficult to characterize in generic microfluidic experiments, can be the source of a plethora of hysteretical phenomena, including the pinning of nanobubbles. PMID:26721395

  8. Wetting hysteresis induced by nanodefects

    PubMed Central

    Giacomello, Alberto; Schimmele, Lothar; Dietrich, Siegfried

    2016-01-01

    Wetting of actual surfaces involves diverse hysteretic phenomena stemming from ever-present imperfections. Here, we clarify the origin of wetting hysteresis for a liquid front advancing or receding across an isolated defect of nanometric size. Various kinds of chemical and topographical nanodefects, which represent salient features of actual heterogeneous surfaces, are investigated. The most probable wetting path across surface heterogeneities is identified by combining, within an innovative approach, microscopic classical density functional theory and the string method devised for the study of rare events. The computed rugged free-energy landscape demonstrates that hysteresis emerges as a consequence of metastable pinning of the liquid front at the defects; the barriers for thermally activated defect crossing, the pinning force, and hysteresis are quantified and related to the geometry and chemistry of the defects allowing for the occurrence of nanoscopic effects. The main result of our calculations is that even weak nanoscale defects, which are difficult to characterize in generic microfluidic experiments, can be the source of a plethora of hysteretical phenomena, including the pinning of nanobubbles. PMID:26721395

  9. Contact angle hysteresis: a molecular interpretation

    SciTech Connect

    Schwartz, A.M.

    1980-06-01

    Contact angle hysteresis in solid-liquid-fluid systems has been explained on the basis of surface roughness, surface heterogeneity, and in certain special cases by penetration of the liquid into the solid surface. However, there are many nonpenetrated solid surfaces that show no hysteresis with certain liquid-fluid pairs but considerable hysteresis with other liquid-fluid pairs having comparable molecular volumes. For experimentation on contact angles such surfaces must be regarded as smooth and homogeneous, at least to liquids in the stipulated range of molecular volume. Any contact angle hysteresis in systems that meet these criteria of smoothness and molecular volume is referred to as intrinsic hysteresis. This work proposes an explanation of intrinsic hysteresis that is in accord with thermodynamic and mechanical principles, and whose validity can be explored experimentally.

  10. Contact angle hysteresis on fluoropolymer surfaces.

    PubMed

    Tavana, H; Jehnichen, D; Grundke, K; Hair, M L; Neumann, A W

    2007-10-31

    Contact angle hysteresis of liquids with different molecular and geometrical properties on high quality films of four fluoropolymers was studied. A number of different causes are identified for hysteresis. With n-alkanes as probe liquids, contact angle hysteresis is found to be strongly related to the configuration of polymer chains. The largest hysteresis is obtained with amorphous polymers whereas the smallest hysteresis occurs for polymers with ordered molecular chains. This is explained in terms of sorption of liquid by the solid and penetration of liquid into the polymer film. Correlation of contact angle hysteresis with the size of n-alkane molecules supports this conclusion. On the films of two amorphous fluoropolymers with different molecular configurations, contact angle hysteresis of one and the same liquid with "bulky" molecules is shown to be quite different. On the surfaces of Teflon AF 1600, with stiff molecular chains, the receding angles of the probe liquids are independent of contact time between solid and liquid and similar hysteresis is obtained for all the liquids. Retention of liquid molecules on the solid surface is proposed as the most likely cause of hysteresis in these systems. On the other hand, with EGC-1700 films that consist of flexible chains, the receding angles are strongly time-dependent and the hysteresis is large. Contact angle hysteresis increases even further when liquids with strong dipolar intermolecular forces are used. In this case, major reorganization of EGC-1700 chains due to contact with the test liquids is suggested as the cause. The effect of rate of motion of the three-phase line on the advancing and receding contact angles, and therefore contact angle hysteresis, is investigated. For low viscous liquids, contact angles are independent of the drop front velocity up to approximately 10 mm/min. This agrees with the results of an earlier study that showed that the rate-dependence of the contact angles is an issue only for liquids with high viscosity. PMID:17537391

  11. Hysteresis and Frequency Tunability of Gyrotrons

    NASA Astrophysics Data System (ADS)

    Dumbrajs, O.; Khutoryan, E. M.; Idehara, T.

    2016-01-01

    We present the first devoted theoretical and experimental study of the hysteresis phenomenon in relation to frequency tunability of gyrotrons. In addition, we generalize the theory describing electron tuning of frequency in gyrotrons developed earlier to arbitrary harmonics. It is found that theoretical magnetic and voltage hysteresis loops are about two times larger than experimental loops. In gyrotrons whose cavities have high quality factors, hysteresis allows one only little to broaden the frequency tunability range.

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

    SciTech Connect

    Professor Isaak Mayergoyz

    2006-08-21

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

  13. Hysteresis and coercivity of hematite

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  14. Hysteresis in the phase transition of chocolate

    NASA Astrophysics Data System (ADS)

    Ren, Ruilong; Lu, Qunfeng; Lin, Sihua; Dong, Xiaoyan; Fu, Hao; Wu, Shaoyi; Wu, Minghe; Teng, Baohua

    2016-01-01

    We designed an experiment to reproduce the hysteresis phenomenon of chocolate appearing in the heating and cooling process, and then established a model to relate the solidification degree to the order parameter. Based on the Landau–Devonshire theory, our model gave a description of the hysteresis phenomenon in chocolate, which lays the foundations for the study of the phase transition behavior of chocolate.

  15. Hysteresis in a quantized superfluid `atomtronic' circuit

    NASA Astrophysics Data System (ADS)

    Eckel, Stephen; Lee, Jeffrey G.; Jendrzejewski, Fred; Murray, Noel; Clark, Charles W.; Lobb, Christopher J.; Phillips, William D.; Edwards, Mark; Campbell, Gretchen K.

    2014-02-01

    Atomtronics is an emerging interdisciplinary field that seeks to develop new functional methods by creating devices and circuits where ultracold atoms, often superfluids, have a role analogous to that of electrons in electronics. Hysteresis is widely used in electronic circuits--it is routinely observed in superconducting circuits and is essential in radio-frequency superconducting quantum interference devices. Furthermore, it is as fundamental to superfluidity (and superconductivity) as quantized persistent currents, critical velocity and Josephson effects. Nevertheless, despite multiple theoretical predictions, hysteresis has not been previously observed in any superfluid, atomic-gas Bose-Einstein condensate. Here we directly detect hysteresis between quantized circulation states in an atomtronic circuit formed from a ring of superfluid Bose-Einstein condensate obstructed by a rotating weak link (a region of low atomic density). This contrasts with previous experiments on superfluid liquid helium where hysteresis was observed directly in systems in which the quantization of flow could not be observed, and indirectly in systems that showed quantized flow. Our techniques allow us to tune the size of the hysteresis loop and to consider the fundamental excitations that accompany hysteresis. The results suggest that the relevant excitations involved in hysteresis are vortices, and indicate that dissipation has an important role in the dynamics. Controlled hysteresis in atomtronic circuits may prove to be a crucial feature for the development of practical devices, just as it has in electronic circuits such as memories, digital noise filters (for example Schmitt triggers) and magnetometers (for example superconducting quantum interference devices).

  16. Corneal hysteresis and its relevance to glaucoma

    PubMed Central

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

    2015-01-01

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

  17. 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.

  18. 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.

  19. Mesoscopic magnetomechanical hysteresis in a magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  20. Anomalous Hysteresis in Perovskite Solar Cells.

    PubMed

    Snaith, Henry J; Abate, Antonio; Ball, James M; Eperon, Giles E; Leijtens, Tomas; Noel, Nakita K; Stranks, Samuel D; Wang, Jacob Tse-Wei; Wojciechowski, Konrad; Zhang, Wei

    2014-05-01

    Perovskite solar cells have rapidly risen to the forefront of emerging photovoltaic technologies, exhibiting rapidly rising efficiencies. This is likely to continue to rise, but in the development of these solar cells there are unusual characteristics that have arisen, specifically an anomalous hysteresis in the current-voltage curves. We identify this phenomenon and show some examples of factors that make the hysteresis more or less extreme. We also demonstrate stabilized power output under working conditions and suggest that this is a useful parameter to present, alongside the current-voltage scan derived power conversion efficiency. We hypothesize three possible origins of the effect and discuss its implications on device efficiency and future research directions. Understanding and resolving the hysteresis is essential for further progress and is likely to lead to a further step improvement in performance. PMID:26270088

  1. Hysteresis modeling in graphene field effect transistors

    SciTech Connect

    Winters, M.; Rorsman, N.; Sveinbjrnsson, E. .

    2015-02-21

    Graphene field effect transistors with an Al{sub 2}O{sub 3} gate dielectric are fabricated on H-intercalated bilayer graphene grown on semi-insulating 4H-SiC by chemical vapour deposition. DC measurements of the gate voltage v{sub g} versus the drain current i{sub d} reveal a severe hysteresis of clockwise orientation. A capacitive model is used to derive the relationship between the applied gate voltage and the Fermi energy. The electron transport equations are then used to calculate the drain current for a given applied gate voltage. The hysteresis in measured data is then modeled via a modified Preisach kernel.

  2. 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.

  3. Managing Hysteresis: Three Cornerstones to Fiscal Stability

    ERIC Educational Resources Information Center

    Weeks, Richard

    2012-01-01

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

  4. Macroscopic theory for capillary-pressure hysteresis.

    PubMed

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

    2015-03-01

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

  5. Managing Hysteresis: Three Cornerstones to Fiscal Stability

    ERIC Educational Resources Information Center

    Weeks, Richard

    2012-01-01

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

  6. Reduction of hysteresis in PI-controlled systems

    SciTech Connect

    Krakow, K.I.

    1998-10-01

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

  7. Contact angle hysteresis in electrowetting on dielectric

    NASA Astrophysics Data System (ADS)

    Zhao, Rui; Liu, Qi-Chao; Wang, Ping; Liang, Zhong-Cheng

    2015-08-01

    Contact angle hysteresis (CAH) is one of the significant physical phenomena in electrowetting on dielectric (EWOD). In this work, a theoretical model is proposed to characterize electrowetting evolution on substrates with CAH, and the relationship among apparent contact angle, potential, and some other parameters is quantified. And this theory is also validated experimentally. The results indicate that our theory and equation based on energy balance succeed in describing the electrowetting response of potential with significant contact angle hysteresis. The CAH in EWOD, ranging from 0 to about 20 in electrowetting cycle, increases with the increase of voltage and climbs up to about 20 when voltage is increased to about 38 V, and then decreases to zero with the further increase of voltage. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2011752).

  8. 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.

  9. Rotational hysteresis of exchange-spring magnets.

    SciTech Connect

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

    2002-03-27

    We highlight our experimental studies and micromagnetic simulations of the rotational hysteresis in exchange-spring magnets. Magneto-optical imaging and torque magnetometry measurements for SmCo/Fe exchange-spring films with uniaxial in-plane anisotropy show that the magnetization rotation created in the magnetically soft Fe layer by a rotating magnetic field is hysteretic. The rotational hysteresis is due to the reversal of the chirality of the spin spiral structure. Micromagnetic simulations reveal two reversal modes of the chirality, one at low fields due to an in-plane untwisting of the spiral, and the other, at high fields, due to an out-of-plane fanning of the spiral.

  10. Correlations between adhesion hysteresis and friction at molecular scales

    NASA Astrophysics Data System (ADS)

    Szoszkiewicz, R.; Bhushan, B.; Huey, B. D.; Kulik, A. J.; Gremaud, G.

    2005-04-01

    Correlations between adhesion hysteresis and local friction are theoretically and experimentally investigated. The model is based on the classical theory of adhesional friction, contact mechanics, capillary hysteresis, and nanoscale roughness. Adhesion hysteresis was found to scale with friction through the scaling factor containing a varying ratio of adhesion energy over the reduced Young's modulus. Capillary forces can offset the relationship between adhesion hysteresis and friction. Measurements on a wide range of engineering samples with varying adhesive and elastic properties confirm the model. Adhesion hysteresis is investigated under controlled, low humidity atmosphere via ultrasonic force microscopy. Friction is measured by the friction force microscopy.

  11. Hysteresis prediction inside magnetic shields and application

    SciTech Connect

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

    2014-07-15

    We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60 μT. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  13. Method and apparatus for sub-hysteresis discrimination

    DOEpatents

    De Geronimo, Gianluigi

    2015-12-29

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

  14. Hysteresis between Distinct Modes of Turbulent Dynamos

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  15. Residual stresses and vector hysteresis modeling

    NASA Astrophysics Data System (ADS)

    Ktena, Aphrodite

    2016-04-01

    Residual stresses in magnetic materials, whether the result of processing or intentional loading, leave their footprint on macroscopic data, such hysteresis loops and differential permeability measurements. A Preisach-type vector model is used to reproduce the phenomenology observed based on assumptions deduced from the data: internal stresses lead to smaller and misaligned grains, hence increased domain wall pinning and angular dispersion of local easy axes, favouring rotation as a magnetization reversal mechanism; misaligned grains contribute to magnetostatic fields opposing the direction of the applied field. The model is using a vector operator which accounts for both reversible and irreversible processes; the Preisach concept for interactions for the role of stress related demagnetizing fields; and a characteristic probability density function which is constructed as a weighed sum of constituent functions: the material is modeled as consisting of various subsystems, e.g. reversal mechanisms or areas subject to strong/weak long range interactions and each subsystem is represented by a constituent probability density function. Our assumptions are validated since the model reproduces the hysteresis loops and differential permeability curves observed experimentally and calculations involving rotating inputs at various residual stress levels are consistent and in agreement with experimental evidence.

  16. Hysteresis and feedback of ice sheet response

    NASA Astrophysics Data System (ADS)

    Abe-Ouchi, A.; Saito, F.; Takahashi, K.

    2014-12-01

    Investigating the response of ice sheets to climatic forcings in the past by climate-ice sheet modelling is important for understanding the ice sheets' change. The 100-kyr cycle of the large Northern Hemisphere ice sheets and fast termination of the glacial cycle are the prominent pattern known from paleoclimate records. We simulate the past glacial cycles with an ice sheet model, IcIES in combination with a general circulation model, MIROC, using the time series of insolation and atmospheric CO2. Feedback processes between ice sheet and atmosphere such as the ice albedo feedback, the elevation-mass balance feedback, desertification effect and stationary wave feedback are analyzed. We show that the threshold of termination of the glacial cycles can be explained by the pattern of the hysteresis of ice sheet change, i.e. multiple steady states of the ice sheets under climatic forcings. We find that slope of the upper branch of the multiple equilibria curve for Laurentide ice volumes is fundamental for the observed glacial patterns. Finally, we discuss the similarity and difference between the hysteresis structure of ice sheets variation for Northern Hemisphere ice sheets, Antarctica and Greenland.

  17. Percolation and hysteresis in macroscopic capillarity

    NASA Astrophysics Data System (ADS)

    Hilfer, Rudolf

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Ak?nc?, mit

    2016-01-01

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

  19. Asymmetric hysteresis loop in magnetostatic-biased multilayer nanowires.

    PubMed

    Allende, S; Escrig, J; Altbir, D; Salcedo, E; Bahiana, M

    2009-11-01

    The hysteresis of multilayer nanowires composed by a soft magnetic cylindrical wire, a non-magnetic spacer layer and an external hard magnetic shell is investigated. The external magnetic shell originates a non-homogeneous magnetic field on the inner wire, which is responsible for a displacement and a change of the width of the hysteresis curve of the wire. Moreover, different reversal modes occur at each branch of the hysteresis loop, which can be understood by analyzing the interaction magnetostatic field along the wire. Our results open the possibility of controlling two parameters of the hysteresis loop, the coercivity and the bias, providing an interesting system to be investigated. PMID:19809104

  20. Experimental comparison of rate-dependent hysteresis models in characterizing and compensating hysteresis of piezoelectric tube actuators

    NASA Astrophysics Data System (ADS)

    Aljanaideh, Omar; Habineza, Didace; Rakotondrabe, Micky; Al Janaideh, Mohammad

    2016-04-01

    An experimental study has been carried out to characterize rate-dependent hysteresis of a piezoelectric tube actuator at different excitation frequencies. The experimental measurements were followed by modeling and compensation of the hysteresis nonlinearities of the piezoelectric tube actuator using both the inverse rate-dependent Prandtl-Ishlinskii model (RDPI) and inverse rate-independent Prandtl-Ishlinskii model (RIPI) coupled with a controller. The comparison of hysteresis modeling and compensation of the actuator with both models is presented.

  1. Hysteresis of misaligned hard-soft grains

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  2. Thermal hysteresis behaviors of thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Iwasaki, Hideo

    2014-12-01

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

  3. Windmill speed limiting system utilizing hysteresis

    SciTech Connect

    Barnes, D.R.

    1983-02-22

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

  4. A Hysteresis Model for Piezoceramic Materials

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.; Ounaies, Zoubeida

    1999-01-01

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

  5. Contact angle hysteresis on superhydrophobic stripes

    NASA Astrophysics Data System (ADS)

    Dubov, Alexander L.; Mourran, Ahmed; Mller, Martin; Vinogradova, Olga I.

    2014-08-01

    We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ?S. It is shown that the receding regime is determined by a longitudinal sliding motion of the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e., is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with ?S. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ? _S^2 ln ? _S. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ?S, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at ?S ? 0.5. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be caused by the adhesion of the drop on solid sectors and is proportional to ? _S^2. Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ?S ? 0.2.

  6. 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

  7. Contact angle hysteresis on superhydrophobic stripes.

    PubMed

    Dubov, Alexander L; Mourran, Ahmed; Mller, Martin; Vinogradova, Olga I

    2014-08-21

    We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ?S. It is shown that the receding regime is determined by a longitudinal sliding motion of the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e., is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with ?S. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ?S(2)ln?S. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ?S, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at ?S ? 0.5. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be caused by the adhesion of the drop on solid sectors and is proportional to ?S(2). Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ?S ? 0.2. PMID:25149809

  8. Discharge mode transition and hysteresis in inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Chang; Kim, Dong-Hwan; Chung, Chin-Wook

    2013-06-01

    Experimental verification of the discharge mode transition and the hysteresis by considering matching circuit is investigated in inductively coupled plasma using measurements of the plasma density and the power absorption to the plasma. At an argon gas pressure of 100 mTorr where the hysteresis loop of the plasma density had been observed in some previous experiments, there is no hysteresis loop against either the input power or the absorbed power delivered via an automatic impedance matching network. At a higher gas pressure of 350 mTorr, however, the hysteresis loop is clearly seen as functions of both the absorbed power and the input power. This result suggests that the observed hysteresis is due to not only the matching effect but also the nonlinearity of the plasma during capacitive (E) to inductive (H) and H to E heating mode transitions.

  9. Hysteresis Compensation for a Piezo Deformable Mirror - Poster Paper

    NASA Astrophysics Data System (ADS)

    Song, H.; Fraanje, R.; Schitter, G.; Verhaegen, M.; Vdovin, G.

    2008-01-01

    The field of adaptive optics (AO) has received rapidly increasing attention in recent years, the intrinsic hysteresis of the piezo deformable mirror (DM) imposes a limit in the accuracy when the stroke of the piezo-actuator is on the order of micrometers. This contribution discusses the hysteresis compensation of a piezo DM by an inverse Preisach hysteresis model. The inverse Preisach hysteresis model is identified from the measured input-output data with a neural network and with a hinging hyperplane based approach. Experimental results demonstrate that hysteresis of the piezo-actuator can be reduced from 20% to about 6% and 9% by the neural network and by the hinging hyperplanes, respectively.

  10. Bias magnetic field and test period dependences of magnetoelectric hysteresis of particulate multiferroic composites

    NASA Astrophysics Data System (ADS)

    Zhou, Yun; Zhou, Hao-Miao; Ye, You-Xiang; Jiao, Zhi-Wei

    2016-03-01

    Magnetoelectric hysteresis behavior for four particulate multiferroic composites with different coercivities of magnetic hysteresis loops has been investigated, and the results show that the magnetoelectric hysteresis are deeply affected by the bias magnetic field and test period. The bias magnetic field dependence of ME hysteresis loops is associated with magnetic hysteresis loops, and the sample with large coercivity of magnetic hysteresis loops has high coercive field of magnetoelectric hysteresis loops. The test time hysteresis caused by fast varying bias magnetic field can be eliminated by prolonging test period. These findings provide some ideas not only for practical applications but also for the examination of magnetoelectric effect.

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

    PubMed Central

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

    2015-01-01

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

  12. Titration and hysteresis in epigenetic chromatin silencing

    NASA Astrophysics Data System (ADS)

    Dayarian, Adel; Sengupta, Anirvan M.

    2013-06-01

    Epigenetic mechanisms of silencing via heritable chromatin modifications play a major role in gene regulation and cell fate specification. We consider a model of epigenetic chromatin silencing in budding yeast and study the bifurcation diagram and characterize the bistable and the monostable regimes. The main focus of this paper is to examine how the perturbations altering the activity of histone modifying enzymes affect the epigenetic states. We analyze the implications of having the total number of silencing proteins, given by the sum of proteins bound to the nucleosomes and the ones available in the ambient, to be constant. This constraint couples different regions of chromatin through the shared reservoir of ambient silencing proteins. We show that the response of the system to perturbations depends dramatically on the titration effect caused by the above constraint. In particular, for a certain range of overall abundance of silencing proteins, the hysteresis loop changes qualitatively with certain jump replaced by continuous merger of different states. In addition, we find a nonmonotonic dependence of gene expression on the rate of histone deacetylation activity of Sir2. We discuss how these qualitative predictions of our model could be compared with experimental studies of the yeast system under anti-silencing drugs.

  13. Experiments on sorption hysteresis of desiccant materials

    SciTech Connect

    Pesaran, A.; Zangrando, F.

    1984-08-01

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

  14. 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.

  15. Hysteresis and transition in swirling nonpremixed flames

    SciTech Connect

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

    2009-02-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

  17. 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.

  18. Eliminating hysteresis of piezoelectric deformable mirror by charge control

    NASA Astrophysics Data System (ADS)

    Ma, Jianqiang; Chen, Junjie; Hu, Yanlei; Tian, Lei; Li, Baoqing; Chu, Jiaru

    2015-08-01

    Inherent hysteresis of piezoelectric deformable mirror (DM) limits the performance of adaptive optics (AO) systems including bandwidth and residual wavefront error. A charge control method based on switched capacitor charge pump was proposed to eliminate the hysteresis of piezoelectric DM. Experimental results show that the hysteresis of a unimorph DM was reduced from 11% to less than 1%. It indicates that the proposed charge control method has the potential to improve the deformation precision for one step correction as well as the bandwidth of the AO systems.

  19. Adaptive feed-forward hysteresis compensation for piezoelectric actuators.

    PubMed

    Eielsen, Arnfinn Aas; Gravdahl, Jan Tommy; Pettersen, Kristin Y

    2012-08-01

    Piezoelectric actuators are often employed for high-resolution positioning tasks. Hysteresis and creep nonlinearities inherent in such actuators deteriorate positioning accuracy. An online adaptive nonlinear hysteresis compensation scheme for the case of symmetric hysteretic responses and certain periodic reference trajectories is presented. The method has low complexity and is well suited for real-time implementation. Experimental results are presented in order to verify the method, and it is seen that the error due to hysteresis is reduced by more than 90% compared to when assuming a linear response. PMID:22938325

  20. On the question of hysteresis in Hall magnetohydrodynamic reconnection

    SciTech Connect

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

    2010-11-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  2. Thermal hysteresis induced by ammonium polyacrylate as antifreeze polymer

    NASA Astrophysics Data System (ADS)

    Funakoshi, Kunio; Inada, Takaaki; Tomita, Takashi; Kawahara, Hidehisa; Miyata, Takashi

    2008-07-01

    Growth and melting rates of a single crystal of ice in ammonium polyacrylate (NH 4PA) aqueous solutions were measured at different solution temperatures, and the morphology of the ice crystals was observed. Thermal hysteresis, defined as the difference between the melting temperature and the non-equilibrium freezing temperature of ice, was confirmed in NH 4PA solutions at concentrations below 25.0 mM. The higher the NH 4PA concentration, the larger the thermal hysteresis, although the thermal hysteresis induced by NH 4PA was much smaller than that induced by antifreeze proteins, antifreeze glycoproteins, or poly(vinyl alcohol). A single crystal of ice grown in the NH 4PA solutions at temperatures within the thermal hysteresis region exhibited the basal faces. When the solution temperature was below the non-equilibrium freezing temperature, the ice crystal grew faster in the a-axis direction than in the c-axis direction, while retaining the basal faces.

  3. PREFACE: International Workshop on Hysteresis & Multi-scale Asymptotics

    NASA Astrophysics Data System (ADS)

    Mortell, Michael; O'Malley, Robert E.; Pokrovskii, Alexei; Sobolev, Vladimir

    2005-01-01

    An International Workshop on Hysteresis & Multi-scale Asymptotics was held at University College Cork, Ireland on March 17-21, 2004. It brought together about 40 active scientists in the areas of dynamical systems with hysteresis and singular perturbations to analyse these phenomena which occur in many industrial, physical and economic systems. The scientific programme of the Workshop can be downloaded from the homepage http://euclid.ucc.ie/hamsa2004.htm. This collection of invited papers is based on the programme of the workshop whose main goal was to analyse and to demonstrate an interaction between theories of systems with multiple scales and systems with hysteresis (and between the 'multi-scale' and 'hysteresis' research communities) as far as possible. To fully understand the paths from singular perturbations to hysteresis and from hysteresis to singular perturbations will continue to involve much work and intense interdisciplinary interactions among experts in the two areas. We mention also two previous workshops: International Workshop on Relaxation Oscillations & Hysteresis, University College Cork, Ireland, April 1-6, 2002. The related collection, edited by us, was published as 'Singular Perturbations and Hysteresis', SIAM, Philadelphia, 2005. http://www.ucc.ie/ucc/depts/physics/ins/roh2002.htm International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics, University College Cork, Ireland, April 5-6, 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, Vol. 5, 2001, No 1 and 2 (edited by Vladimir Gol'dstein, Alexei Pokrovskii and Vladimir Sobolev), and is also available online at http://euclid.ucc.ie/appliedmath/gmna2001/ProcGMNA2001Full.pdf Finally, we wish to gratefully acknowledge the support of the School of Mathematical Sciences and the Boole Centre for Research in Informatics, University College Cork.

  4. 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.

  5. Influence of interfacial dislocations on hysteresis loops of ferroelectric films

    SciTech Connect

    Li, Yulan; Hu, Shenyang Y.; Choudhury, S.; Baskes, Michael I.; Saxena, A.; Lookman, T.; Jia, Q.X.; Schlom, Darrell G.; Chen , L.Q.

    2008-11-15

    We investigated the influence of dislocations, located at the interface of a ferroelectric film and its underlying substrate, on the ferroelectric hysteresis loop including the remanent polarization and coercive field using phase-field simulations. We considered epitaxial ferroelectric BaTiO3 films and found that the hysteresis loop is strongly dependent on the type and density of interfacial dislocations. The dislocations that stabilize multiple ferroelectric variants and domains reduce the coercive field, and consequently, the corresponding remanent polarization also decreases.

  6. Stabilization of supercooled fluids by thermal hysteresis proteins.

    PubMed Central

    Wilson, P W; Leader, J P

    1995-01-01

    It has been reported that thermal hysteresis proteins found in many cold-hardy, freeze-avoiding arthropods stabilize their supercooled body fluids. We give evidence that fish antifreeze proteins, which also produce thermal hysteresis, bind to and reduce the efficiency of heterogenous nucleation sites, rather than binding to embryonic ice nuclei. We discuss both possible mechanisms for stabilization of supercooled body fluids and also describe a new method for measuring and defining the supercooling point of small volumes of liquid. PMID:7612853

  7. Experimental Highlight of Hysteresis Phenomenon in Rolling Contact

    NASA Astrophysics Data System (ADS)

    Alaci, S.; Cerlinc?, D. A.; Ciornei, F. C.; Filote, C.; Frunz?, G.

    2015-02-01

    In literature, the hysteresis phenomenon in rolling contacts is studied considering both rolling friction and sliding friction. Removal of sliding friction in experimental tests from a concentrated contact is a serious challenge. The paper proposes a method and presents a device ensuring pure rolling between two identical discs, normally loaded. Using photoelastic material for the two rolling discs, by means of photoelastic method, the hysteresis phenomenon due to rolling friction is qualitatively confirmed.

  8. Stabilization of supercooled fluids by thermal hysteresis proteins.

    PubMed

    Wilson, P W; Leader, J P

    1995-05-01

    It has been reported that thermal hysteresis proteins found in many cold-hardy, freeze-avoiding arthropods stabilize their supercooled body fluids. We give evidence that fish antifreeze proteins, which also produce thermal hysteresis, bind to and reduce the efficiency of heterogenous nucleation sites, rather than binding to embryonic ice nuclei. We discuss both possible mechanisms for stabilization of supercooled body fluids and also describe a new method for measuring and defining the supercooling point of small volumes of liquid. PMID:7612853

  9. Stiffness and hysteresis properties of some prosthetic feet.

    PubMed

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

    1990-12-01

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

  10. Voltage control of magnetic hysteresis in a nickel nanoparticle

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  11. Dynamic Hysteresis in Compacted Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chowdary, Krishna M.

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

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

    PubMed

    Kristiansen, Erlend; Zachariassen, Karl Erik

    2005-12-01

    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 ice growth is referred to as the hysteresis freezing point. The hysteresis is supposed to be the result of an adsorption of antifreeze proteins to the crystal surface. This causes the ice to grow as convex surface regions between adjacent adsorbed antifreeze proteins, thus lowering the temperature at which the crystal can visibly expand. The model requires that the antifreeze proteins are irreversibly adsorbed onto the ice surface within the hysteresis gap. This presupposition is apparently in conflict with several characteristic features of the phenomenon; the absence of superheating of ice in the presence of antifreeze proteins, the dependence of the hysteresis activity on the concentration of antifreeze proteins and the different capacities of different types of antifreeze proteins to cause thermal hysteresis at equimolar concentrations. In addition, there are structural obstacles that apparently would preclude irreversible adsorption of the antifreeze proteins to the ice surface; the bond strength necessary for irreversible adsorption and the absence of a clearly defined surface to which the antifreeze proteins may adsorb. This article deals with these apparent conflicts between the prevailing theory and the empirical observations. We first review the mechanism of thermal hysteresis with some modifications: we explain the hysteresis as a result of vapour pressure equilibrium between the ice surface and the ambient fluid fraction within the hysteresis gap due to a pressure build-up within the convex growth zones, and the ice growth as the result of an ice surface nucleation event at the hysteresis freezing point. We then go on to summarise the empirical data to show that the dependence of the hysteresis on the concentration of antifreeze proteins arises from an equilibrium exchange of antifreeze proteins between ice and solution at the melting point. This reversible association between antifreeze proteins and the ice is followed by an irreversible adsorption of the antifreeze proteins onto a newly formed crystal plane when the temperature is lowered below the melting point. The formation of the crystal plane is due to a solidification of the interfacial region, and the necessary bond strength is provided by the protein "freezing" to the surface. In essence: the antifreeze proteins are "melted off" the ice at the bulk melting point and "freeze" to the ice as the temperature is reduced to subfreezing temperatures. We explain the different hysteresis activities caused by different types of antifreeze proteins at equimolar concentrations as a consequence of their solubility features during the phase of reversible association between the proteins and the ice, i.e., at the melting point; a low water solubility results in a large fraction of the proteins being associated with the ice at the melting point. This leads to a greater density of irreversibly adsorbed antifreeze proteins at the ice surface when the temperature drops, and thus to a greater hysteresis activity. Reference is also made to observations on insect antifreeze proteins to emphasise the general validity of this approach. PMID:16140290

  13. Adsorption hysteresis for a slit-like pore model

    NASA Astrophysics Data System (ADS)

    Kutarov, V. V.; Tarasevich, Yu. I.; Aksenenko, E. V.; Ivanova, Z. G.

    2011-07-01

    The Frenkel-Halsey-Hill equation is used to describe the adsorption branch of a hysteresis loop upon polylayer adsorption with an H3 loop according to IUPAC nomenclature. The equation for the desorption branch of a hysteresis loop is derived from a combined solution to the equation for the Gibbs potential change, given the adsorbent swelling and pore connectivity function, and the Laplace equation taken for the conditions of infinitely elongated meniscus. This equation is shown to connect the adsorbate relative pressure in a bulk phase for the desorption branch of a hysteresis loop with the key parameters of the adsorption system. The equation obtained was verified by a water adsorption isotherm on natural mineral schungite.

  14. Origin of J-V Hysteresis in Perovskite Solar Cells.

    PubMed

    Chen, Bo; Yang, Mengjin; Priya, Shashank; Zhu, Kai

    2016-03-01

    High-performance perovskite solar cells (PSCs) based on organometal halide perovskite have emerged in the past five years as excellent devices for harvesting solar energy. Some remaining challenges should be resolved to continue the momentum in their development. The photocurrent density-voltage (J-V) responses of the PSCs demonstrate anomalous dependence on the voltage scan direction/rate/range, voltage conditioning history, and device configuration. The hysteretic J-V behavior presents a challenge for determining the accurate power conversion efficiency of the PSCs. Here, we review the recent progress on the investigation of the origin(s) of J-V hysteresis behavior in PSCs. We discuss the impact of slow transient capacitive current, trapping and detrapping process, ion migrations, and ferroelectric polarization on the hysteresis behavior. The remaining issues and future research required toward the understanding of J-V hysteresis in PSCs will also be discussed. PMID:26886052

  15. Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids.

    PubMed

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

    2013-06-01

    Dynamic hysteresis phenomena are widespread in physical sciences and describe the complex behavior of systems driven out of equilibrium by a periodic forcing. We use here paramagnetic colloids above a stripe-patterned garnet film as the model system to study dynamic hysteresis, the latter induced when the particles are periodically translated by an oscillating magnetic field. In contrast to the expected behavior for a bistable system, we observe that the area of the hysteresis loop decreases by increasing the driving frequency and reduces to zero for frequencies higher than 5-7s(-1). To explain the experimental results, we develop a simple model based on an overdamped Brownian particle driven by a periodic potential with an oscillating amplitude. PMID:23848669

  16. Unconventional dynamic hysteresis in a periodic assembly of paramagnetic colloids

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    Dynamic hysteresis phenomena are widespread in physical sciences and describe the complex behavior of systems driven out of equilibrium by a periodic forcing. We use here paramagnetic colloids above a stripe-patterned garnet film as the model system to study dynamic hysteresis, the latter induced when the particles are periodically translated by an oscillating magnetic field. In contrast to the expected behavior for a bistable system, we observe that the area of the hysteresis loop decreases by increasing the driving frequency and reduces to zero for frequencies higher than 5-7s-1. To explain the experimental results, we develop a simple model based on an overdamped Brownian particle driven by a periodic potential with an oscillating amplitude.

  17. 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.

  18. Hysteresis Modeling in Magnetostrictive Materials Via Preisach Operators

    NASA Technical Reports Server (NTRS)

    Smith, R. C.

    1997-01-01

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

  19. Brownian motion of a drop with hysteresis dissipation.

    PubMed

    Chaudhury, Manoj K; Mettu, Srinivas

    2008-06-17

    Small water drops placed on a low-energy substrate with a slight tilt were vibrated parallel to the support with bands of Gaussian white noise of different powers. The drops drifted downward on the inclined support accompanied with random forward and backward movements. For a hysteresis free surface, the drift velocity should only be the product of the component of the gravitational acceleration and the Langevin relaxation time, being independent of the power of noise. On the other hand, in the presence of hysteresis, as is the case here, the drift velocity depends strongly on the power of the noise. This result illustrates the role of hysteresis in the drifted motion of drops on a surface subjected to vibration, which has important bearings on various forms of work fluctuation relations. PMID:18494512

  20. Hysteresis dispersion scaling of a two-dimensional ferroelectric model

    NASA Astrophysics Data System (ADS)

    Wang, L.-F.; Liu, J.-M.

    2005-09-01

    The ferroelectric hysteresis dispersion of a two-dimensional ferroelectric model lattice in an ac electric field of amplitude E0 and frequency ? over a wide range, respectively, is calculated by Monte Carlo simulation based on the Ginzburg-Landau theory on tetragonal-type ferroelectric phase transitions. Given a fixed field amplitude E0, the hysteresis dispersion as a function of field frequency ? shows a single-peaked pattern, which predicts the existence of a characteristic time responsible for domain switching in an external electric field. The scaling analysis demonstrates that given different field amplitudes E0, the hysteresis dispersions can be scaled and the characteristic time depends inversely on the field amplitude E0 over a wide range of E0, but the large deviation occurs as E0 is very small or extremely large.

  1. Hysteresis during lithium insertion in hydrogen-containing carbons

    SciTech Connect

    Zheng, T.; Dahn, J.R.; McKinnon, W.R.

    1996-07-01

    The authors studied lithium insertion in hydrogen-containing carbons heated at temperatures near 700 C. High capacities with large hysteresis (lithium insertion into these carbons at nearly 0 V and removal at nearly 1 V) were shown to be proportional to the hydrogen content of the samples. It is believed that the lithium atoms may bind on hydrogen-terminated edges of hexagonal carbon fragments, causing a change in the bond from sp{sup 2} to sp{sup 3}. The authors have carefully studied the electrochemical insertion of lithium in hydrogen-containing carbons using a variety of charge-discharge rates and cycling temperatures. These measurements allow the hysteresis to be quantified. A simple model, which treats the bonding change as an activated process, is used to model the hysteresis in the cells qualitatively.

  2. Contact Hysteresis and Friction of Alkanethiol SAMs on Au

    SciTech Connect

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

    1998-10-14

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

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

    SciTech Connect

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

    2013-11-14

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

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

    PubMed

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

    1998-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  6. Modeling of Switching and Hysteresis in Molecular Transport

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  7. 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.

  8. A digital charge amplifier for hysteresis elimination in piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Bazghaleh, M.; Grainger, S.; Mohammadzaheri, M.; Cazzolato, B.; Lu, T.-F.

    2013-07-01

    Piezoelectric actuators are commonly used for nanopositioning due to their high resolution, low power consumption and wide operating frequency, but they suffer hysteresis, which affects linearity. In this paper, a novel digital charge amplifier is presented. Results show that hysteresis is reduced by 91% compared with a voltage amplifier, but over long operational periods the digital charge amplifier approach suffers displacement drift. A non-linear ARX model with long-term accuracy is used with a data fusion algorithm to remove the drift. Experimental results are presented.

  9. 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.

  10. 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

  11. Dynamic Contact Angles and Hysteresis under Electrowetting-on-Dielectric

    PubMed Central

    Nelson, Wyatt C.; Sen, Prosenjit; Kim, Chang-Jin CJ

    2011-01-01

    By designing and implementing a new experimental method, we have measured the dynamic advancing and receding contact angles and the resulting hysteresis of droplets under electrowetting-on-dielectric (EWOD). Measurements were obtained over wide ranges of applied EWOD voltages, or electrowetting numbers (0 ? Ew ? 0.9), and droplet sliding speeds, or capillary numbers (1.410-5 ? Ca ? 6.910-3). If Ew or Ca is low, dynamic contact angle hysteresis is not affected much by the EWOD voltage or the sliding speed, i.e., the hysteresis increases by less than 50% with a two order-of-magnitude increase in sliding speed when Ca < 10-3. If both Ew and Ca are high, however, the hysteresis increases with either the EWOD voltage or the sliding speed. Stick-slip oscillations were observed at Ew>0.4. Data are interpreted with simplified hydrodynamic (Cox-Voinov) and molecular-kinetic theory (MKT) models; the Cox-Voinov model captures the trend of the data, but yields unreasonable fitting parameters. MKT fitting parameters associated with the advancing contact line are reasonable, but a lack of symmetry indicates that a more intricate model is required. PMID:21751778

  12. Dynamic hysteresis in the rheology of complex fluids.

    PubMed

    Puisto, Antti; Mohtaschemi, Mikael; Alava, Mikko J; Illa, Xavier

    2015-04-01

    Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak. PMID:25974498

  13. Hysteresis in the phase-slip state of superconducting filaments

    NASA Astrophysics Data System (ADS)

    Kramer, Lorenz; Rangel, Rafael

    1989-04-01

    Recently some papers on measurements of the I-V characteristics (where V is the time-averaged voltage) of superconducting indium microbridges 1 as well as tin and zinc whiskers 2,3 driven by a dc current into the phase-slip state have appeared. Special emphasis was placed on a discussion of the hysteresis, which is well-known in such experiments (see, e.g., Refs. 1 18 in Kramer and Rangel 4 ). The hysteresis was compared with the predictions of the generalized time-dependent Ginzburg-Landau (GTDGL) equations for dirty superconductors in local equilibrium. 4,5 Unfortunately these predictions represent the only results in this context derived ultimately in a rigorous fashion from the standard microscopic theory of superconductivity. Comparison was also made with a model by Kadin, Smith, and Skocpol (KSS), 6,7 which gives a much smaller hysteresis. The authors of Ref. 1 found good agreement with the KSS model. The authors of Refs. 2 and 3 found a hysteresis which is larger than that of the KSS model, but still considerably smaller than predicted by GTDGL theory. They proposed a generalization of KSS which can be fitted to the data.

  14. 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...

  15. Dynamic hysteresis in the rheology of complex fluids

    NASA Astrophysics Data System (ADS)

    Puisto, Antti; Mohtaschemi, Mikael; Alava, Mikko J.; Illa, Xavier

    2015-04-01

    Recently, rheological hysteresis has been studied systematically in a wide range of complex fluids combining global rheology and time-resolved velocimetry. In this paper we present an analysis of the roles of the three most fundamental mechanisms in simple-yield-stress fluids: structure dynamics, viscoelastic response, and spatial flow heterogeneities, i.e., time-dependent shear bands. Dynamical hysteresis simulations are done analogously to rheological ramp-up and -down experiments on a coupled model which incorporates viscoelasticity and time-dependent structure evolution. Based on experimental data, a coupling between hysteresis measured from the local velocity profiles and that measured from the global flow curve has been suggested. According to the present model, even if transient shear banding appears during the shear ramps, in typical narrow-gap devices, only a small part of the hysteretic response can be attributed to heterogeneous flow. This results in decoupling of the hysteresis measured from the local velocity profiles and the global flow curve, demonstrating that for an arbitrary time-dependent rheological response this proposed coupling can be very weak.

  16. Hysteresis modelling of a core-free EAP tubular actuator

    NASA Astrophysics Data System (ADS)

    Sarban, Rahimullah; Oubaek, Jakob; Kristjnsdttir, Gisla R.; Jones, Richard W.

    2009-03-01

    This work investigates the characterization and modelling of hysteresis in a core-free dielectric electro-active polymer (EAP) tubular actuator. The overall hysteresis effect of the voltage driven system comprises the inherent hysteresis of the fabricated tubular actuator plus a time lag introduced by the associated power supply when charging and discharging the actuator. Specifically the dynamic asymmetric hysteretic model of the voltage driven tubular actuator is decomposed into two models in series, comprising the nonlinear static voltage-strain characteristic of the actuator and an approximate symmetric hysteretic characteristic. The Bouc-Wen model approach is popular in engineering because of its simple interpretation as a nonlinear black-box model, the relatively low number of parameters needed to describe it, and the availability of both optimization and least squares estimation approaches to identify model parameters from experimental data. A disadvantage of the Bouc-Wen modelling approach is that it cannot accurately model asymmetric hysteresis behaviour. The use of the decomposition approach allows the Bouc-Wen model to be used to describe the approximate symmetric hysteretic characteristic. The model parameters are identified using an evolutionary computational algorithm - particle swarm optimization (PSO). PSO is an evolutionary based optimization approach that has been shown to be superior to genetic algorithms.

  17. Small hysteresis and high energy storage power of antiferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Wang, Jinfei; Yang, Tongqing; Chen, Shengchen; Yao, Xi

    2014-09-01

    In this paper, modified Pb(Zr,Ti)O3(PZT) antiferroelectric (AFE) ceramics system was investigated by traditional solid state method. It was observed that the effect of different contents of Zr/Sn, Zr/Ti on modified PZT antiferroelectrics. With increasing Zr/Sn content, the EAFE (electric field of AFE phase to ferroelectric (FE) phase) value was enlarged. The phase switch field was reduced from FE to AFE (EFA). The hysteresis loops were changed from "slanted" to "square"-types. With increasing Zr/Ti concentrate, the EAFE value, and also the EFA was enlarged, while the hysteresis switch ?E was reduced. The hysteresis loops was from "square" to "slanted"-types. The samples with square hysteresis loops are suitable for energy storage capacitor applications, the composition of ceramics was Pb0.97La0.02(Zr0.90Sn0.05Ti0.05)O3, which have the largest energy storage density 4.426J/cm3 at 227 kV/cm, and ?E was 80 kV/cm, energy efficient ? was about 0.612.

  18. Intrinsic Hysteresis Loops Calculation of BZT Thin Films

    NASA Astrophysics Data System (ADS)

    Hikam, M.; Adnan, S. R.

    2014-04-01

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

  19. Hysteresis dynamics, bursting oscillations and evolution to chaotic regimes.

    PubMed

    Franoise, J-P; Piquet, C

    2005-01-01

    This article describes new aspects of hysteresis dynamics which have been uncovered through computer experiments. There are several motivations to be interested in fast-slow dynamics. For instance, many physiological or biological systems display different time scales. The bursting oscillations which can be observed in neurons, beta-cells of the pancreas and population dynamics are essentially studied via bifurcation theory and analysis of fast-slow systems (Keener and Sneyd, 1998; Rinzel, 1987). Hysteresis is a possible mechanism to generate bursting oscillations. A first part of this article presents the computer techniques (the dotted-phase portrait, the bifurcation of the fast dynamics and the wave form) we have used to represent several patterns specific to hysteresis dynamics. This framework yields a natural generalization to the notion of bursting oscillations where, for instance, the active phase is chaotic and alternates with a quiescent phase. In a second part of the article, we emphasize the evolution to chaos which is often associated with bursting oscillations on the specific example of the Hindmarsh-Rose system. This evolution to chaos has already been studied with classical tools of dynamical systems but we give here numerical evidence on hysteresis dynamics and on some aspects of the wave form. The analytical proofs will be given elsewhere. PMID:16583277

  20. Pseudo-elastic hysteresis in shape memory alloys

    NASA Astrophysics Data System (ADS)

    Müller, I.

    2012-05-01

    Observations of pseudo-elastic hysteresis loops in the shape memory alloy CuAlNi are presented. Particular emphasis is laid on the interior of the overall loop and the phenomena of internal yield and recovery and internal loops are discussed. A thermodynamic argument is presented which may afford an interpretation of the observed phenomena in terms of interfacial energies.

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

    PubMed

    Park, Jongkyu; Moon, Wonkyu

    2010-03-01

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

  2. Influence of contact angle on hysteresis in mercury porosimetry

    SciTech Connect

    Lowell, S.; Shields, J.E.

    1981-03-01

    A study of the effect of contact angle in mercury porosimetry has revealed that appropriate adjustments in the angle result in the elimination of intrusion-extrusion hysteresis. When the contact angle is increased for the intrusion curve and decreased for the extrusion curve, the two curves can be brought into coincidence.

  3. A simple model of hysteresis behavior using spreadsheet analysis

    NASA Astrophysics Data System (ADS)

    Ehrmann, A.; Blachowicz, T.

    2015-01-01

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

  4. Crystal field dilution in S-1 Blume Capel model: Hysteresis behaviors

    NASA Astrophysics Data System (ADS)

    Akıncı, Ümit

    2016-03-01

    Hysteresis characteristics of the crystal field diluted S-1 Ising (Blume-Capel) model have been studied within the effective field approximation. Paramagnetic and double hysteresis behaviors for the paramagnetic phase have been obtained. It has also been shown that, for the ferromagnetic phase of the system, single and triple hysteresis behaviors may occur. Regions that show these different hysteresis behaviors are explicitly obtained in the space of Hamiltonian parameters. Besides, physical mechanisms that give rise to these behaviors have been given.

  5. 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 gratefully acknowledged. The Editors and the Organizers of the Workshop wish to place on record their sincere gratitude to Mr Andrew Zhezherun and Mr Alexander Pimenov of University College Cork for both the assistance which he provided to all the presenters at the Workshop, and for the careful formatting of all the manuscripts prior to their being forwarded to the Publisher. More information about the Workshop can be found at http://euclid.ucc.ie/murphys2006.htm Michael P Mortell, Robert E O'Malley Jr, Alexei Pokrovskii, Dmitrii Rachinskii and Vladimir Sobolev Editors

  6. Hysteresis and Kinetic Effects During Liquid-Solid Transitions

    SciTech Connect

    Streitz, F H; Chau, R

    2009-02-17

    We address the fundamental issue of phase transition kinetics in dynamically compressed materials. Focusing on solid bismuth (Bi) as a prototype material, we used a variety of time-resolved experiments including electrical conductivity and velocimetry to study the phase transition kinetics of the solid-solid phase transitions. Simple single shock experiments performed on several low-lying high pressure phases of Bi, revealed surprisingly complex behavior and slow dynamics. Strong hysteresis effects were observed in the transition behavior in experiments where the compressed Bi was allowed to release back across a phase line. These experiments represent the first reported simultaneous use of resistivity and velocimetry in a shock compression experiment, and the first observation of hysteresis effects occurring during dynamic compression and release.

  7. 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.

  8. Study on thermal hysteresis of Sr doped manganites

    NASA Astrophysics Data System (ADS)

    Singh, Bharat; Kumar, Naresh; Mohan, Rajneesh; Bhattacharya, S.; Gaur, N. K.

    2013-06-01

    We have studied the thermal hysteresis of dc electrical resistivity on the stoichiometric Nd0.67Sr0.33MnO3 and Pr0.67Sr0.33MnO3 manganites. The polycrystalline samples have been synthesized by solid state reaction method. The prepared samples were characterized by X-ray diffraction (XRD) for phase formation and low temperature dc resistivity measurement during both cooling and warming with standard four probe technique. The XRD patterns are indexed in orthorhombic unit cell (space group-Pnma). The resistivity data show a metal-insulator phase transition for both Pr0.67Sr0.33MnO3 and Nd0.67Sr0.33MnO3 samples with observable thermal hysteresis. Thermal coefficient of resistivity of all samples has also been studied.

  9. Attachment/detachment hysteresis of fiber-based magnetic grabbers.

    PubMed

    Gu, Yu; Kornev, Konstantin G

    2014-04-28

    We developed an experimental protocol to analyze the behaviour of a model fiber-based magnetic grabber. A fiber is vertically suspended and fixed to the substrate by its upper end. A magnetic droplet is attached to the free end of the fiber and when a permanent magnet approaches the droplet, the fiber is forced to bow and finally jumps to the magnet. It appears that one can flex the micro-fibers by very small micro or even nano-Newton forces. Using this setup, we discovered a hysteresis of fiber attachment/detachment: the pathway of the fiber jumping to and off the magnet depends on the distance between the magnet and the clamped end. This phenomenon was successfully explained by the Euler-Benoulli model of an elastic beam. The observed hysteresis of fiber attachment/detachment was attributed to the multiple equilibrium configurations of the fiber tip placed in a dipole-type magnetic field. PMID:24668160

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

    NASA Astrophysics Data System (ADS)

    Carbone, Giuseppe; Pierro, Elena; Recchia, Giuseppina

    2015-12-01

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

  11. Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization

    PubMed Central

    Farrahi, Assal; Sanz-Andrés, Ángel

    2013-01-01

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

  12. Voltage hysteresis of lithium ion batteries caused by mechanical stress.

    PubMed

    Lu, Bo; Song, Yicheng; Zhang, Qinglin; Pan, Jie; Cheng, Yang-Tse; Zhang, Junqian

    2016-02-01

    The crucial role of mechanical stress in voltage hysteresis of lithium ion batteries in charge-discharge cycles is investigated theoretically and experimentally. A modified Butler-Volmer equation of electrochemical kinetics is proposed to account for the influence of mechanical stresses on electrochemical reactions in lithium ion battery electrodes. It is found that the compressive stress in the surface layer of active materials impedes lithium intercalation, and therefore, an extra electrical overpotential is needed to overcome the reaction barrier induced by the stress. The theoretical formulation has produced a linear dependence of the height of voltage hysteresis on the hydrostatic stress difference between lithiation and delithiation, under both open-circuit conditions and galvanostatic operation. Predictions of the electrical overpotential from theoretical equations agree well with the experimental data for thin film silicon electrodes. PMID:26799574

  13. Degradation and capacitance: voltage hysteresis in CdTe devices

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

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

    SciTech Connect

    Vengrinovich, Valeriy

    2014-02-18

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

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

    SciTech Connect

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

    1998-06-01

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

  16. Hysteresis compensation for a piezoelectric fiber optic voltage sensor

    NASA Astrophysics Data System (ADS)

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

    2005-11-01

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

  17. Scaling law for dynamical hysteresis of cavity solitons

    NASA Astrophysics Data System (ADS)

    Ahmadipanah, Sahar; Kheradmand, Reza; Prati, Franco

    2016-02-01

    By applying to a cavity soliton a control beam modulated in time, we study numerically the performance of the soliton as a flip–flop memory. The soliton is switched on and off periodically through a hysteresis cycle whose size increases dynamically with the modulation frequency. We show that the phenomenon is ruled by a scaling law with an exponent compatible with the theoretical value 2/3 predicted in much simpler systems in the low-frequency limit.

  18. Hysteresis effects of changing the parameters of noncooperative games

    NASA Astrophysics Data System (ADS)

    Wolpert, David H.; Harr, Michael; Olbrich, Eckehard; Bertschinger, Nils; Jost, Jrgen

    2012-03-01

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

  19. Relative permeability hysteresis: Laboratory measurements and a conceptual model

    SciTech Connect

    Braun, E.M.; Holland, R.F.

    1995-08-01

    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 scanning curves is their reversibility; along most of the length of a scanning curve, oil relative permeability exhibits no hysteresis. A proposed mechanism for the reversible behavior is pinning of water/oil interfaces on surfaces of rock grains. Pinned interfaces remain anchored at fixed positions on grains despite changes in interface curvature and contact angle. In water-wet samples, pinning can occur as a result of contact-angle hysteresis. In mixed-wet rock, pinning can occur at the boundaries between water- and oil-wet grain surfaces. As long as interfaces remain pinned, pore-level fluid geometry is a function of saturation only and does not depend on the directional of saturation change.

  20. Hysteresis of the resonance frequency of magnetostrictive bending cantilevers

    NASA Astrophysics Data System (ADS)

    Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard

    2015-05-01

    Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ΔE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.

  1. Oscillating hysteresis in the q -neighbor Ising model

    NASA Astrophysics Data System (ADS)

    Jȩdrzejewski, Arkadiusz; Chmiel, Anna; Sznajd-Weron, Katarzyna

    2015-11-01

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

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

    PubMed

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-01-01

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

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

    PubMed Central

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-10-01

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

  5. Dissociated hysteresis of static ocular counterroll in humans.

    PubMed

    Palla, A; Bockisch, C J; Bergamin, O; Straumann, D

    2006-04-01

    In stationary head roll positions, the eyes are cyclodivergent. We asked whether this phenomenon can be explained by a static hysteresis that differs between the eyes contra- (CE) and ipsilateral (IE) to head roll. Using a motorized turntable, healthy human subjects (n = 8) were continuously rotated about the earth-horizontal naso-occipital axis. Starting from the upright position, a total of three full rotations at a constant velocity (2 degrees/s) were completed (acceleration = 0.05 degrees/s2, velocity plateau reached after 40 s). Subjects directed their gaze on a flashing laser dot straight ahead (switched on 20 ms every 2 s). Binocular three-dimensional eye movements were recorded with dual search coils that were modified (wires exiting inferiorly) to minimize torsional artifacts by the eyelids. A sinusoidal function with a first and second harmonic was fitted to torsional eye position as a function of torsional whole body position at constant turntable velocity. The amplitude and phase of the first harmonic differed significantly between the two eyes (paired t-test: P < 0.05): on average, counterroll amplitude of IE was larger [CE: 6.6 +/- 1.6 degrees (SD); IE: 8.1 +/- 1.7 degrees), whereas CE showed more position lag relative to the turntable (CE: 12.5 +/- 10.7 degrees; IE: 5.1 +/- 8.7 degrees). We conclude that cyclodivergence observed during static ocular counterroll is mainly a result of hysteresis that depends on whether eyes are contra- or ipsilateral to head roll. Static hysteresis also explains the phenomenon of residual torsion, i.e., an incomplete torsional return of the eyes when the first 360 degrees whole body rotation was completed and subjects were back in upright position (extorsion of CE: 2.0 +/- 0.10 degrees; intorsion of IE: 1.4 +/- 0.10 degrees). A computer model that includes asymmetric backlash for each eye can explain dissociated torsional hysteresis during quasi-static binocular counterroll. We hypothesize that ocular torsional hysteresis is introduced at the level of the otolith pathways because the direction-dependent torsional position lag of the eyes is related to the head roll position and not the eye position. PMID:16338995

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

    NASA Astrophysics Data System (ADS)

    Martin, Raleigh L.; Jerolmack, Douglas J.

    2013-03-01

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

  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. Anomalous hysteresis properties of iron films deposited on liquid surfaces

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

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

    PubMed

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

    2002-12-16

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

  11. One-phase flow in porous media with hysteresis

    NASA Astrophysics Data System (ADS)

    Botkin, N. D.; Brokate, M.; El Behi-Gornostaeva, E. G.

    2016-04-01

    This paper presents a numerical simulation of one phase flow through a porous medium showing a hysteretic relation between the capillary pressure and the saturation of the phase. The flow model used is based on mass conservation principle and Darcy's law. Boundary conditions of Neumann and Signorini type are imposed. The hysteretic relation between the capillary pressure and the saturation is described by a Preisach hysteresis operator. A numerical algorithm for the treatment of the arising system of equations is proposed. Results of numerical simulations are presented.

  12. A new load-dependent hysteresis model for magnetostrictive materials

    NASA Astrophysics Data System (ADS)

    Valadkhan, Sina; Morris, Kirsten; Shum, Alex

    2010-12-01

    Magnetostrictive materials can be used to construct high bandwidth actuators with a higher force and a larger stroke than are provided by other materials. However, their use is hindered by their complex nonlinear and hysteretic response. This response displays a significant dependence on mechanical loading. In this paper, a modeling technique is introduced for reproducing hysteresis curves at different loads. The classic Preisach model is used, although the approach can be used to include load dependence in other models. Predicted values are compared with the homogenized energy model and also with experimental data.

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

    PubMed

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

    2003-01-31

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

  14. Stability of Soap Films: Hysteresis and Nucleation of Black Films

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

  15. 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.

  16. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Modeling Hysteresis Effect in Three-Phase Relative Permeability

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  19. Ionic Origin of Electro-osmotic Flow Hysteresis

    NASA Astrophysics Data System (ADS)

    Lim, Chun Yee; Lim, An Eng; Lam, Yee Cheong

    2016-02-01

    Electro-osmotic flow, the driving of fluid at nano- or micro- scales with electric field, has found numerous applications, ranging from pumping to chemical and biomedical analyses in micro-devices. Electro-osmotic flow exhibits a puzzling hysteretic behavior when two fluids with different concentrations displace one another. The flow rate is faster when a higher concentration solution displaces a lower concentration one as compared to the flow in the reverse direction. Although electro-osmotic flow is a surface phenomenon, rather counter intuitively we demonstrate that electro-osmotic flow hysteresis originates from the accumulation or depletion of pH-governing minority ions in the bulk of the fluid, due to the imbalance of electric-field-induced ion flux. The pH and flow velocity are changed, depending on the flow direction. The understanding of electro-osmotic flow hysteresis is critical for accurate fluid flow control in microfluidic devices, and maintaining of constant pH in chemical and biological systems under an electric field.

  20. Ionic Origin of Electro-osmotic Flow Hysteresis

    PubMed Central

    Lim, Chun Yee; Lim, An Eng; Lam, Yee Cheong

    2016-01-01

    Electro-osmotic flow, the driving of fluid at nano- or micro- scales with electric field, has found numerous applications, ranging from pumping to chemical and biomedical analyses in micro-devices. Electro-osmotic flow exhibits a puzzling hysteretic behavior when two fluids with different concentrations displace one another. The flow rate is faster when a higher concentration solution displaces a lower concentration one as compared to the flow in the reverse direction. Although electro-osmotic flow is a surface phenomenon, rather counter intuitively we demonstrate that electro-osmotic flow hysteresis originates from the accumulation or depletion of pH-governing minority ions in the bulk of the fluid, due to the imbalance of electric-field-induced ion flux. The pH and flow velocity are changed, depending on the flow direction. The understanding of electro-osmotic flow hysteresis is critical for accurate fluid flow control in microfluidic devices, and maintaining of constant pH in chemical and biological systems under an electric field. PMID:26923197

  1. Rotational versus alternating hysteresis losses in nonoriented soft magnetic laminations

    NASA Astrophysics Data System (ADS)

    Fiorillo, F.; Rietto, A. M.

    1993-05-01

    Rotational and alternating hysteresis losses have been investigated in theory and experiment in nonoriented soft magnetic laminations. Attention has been focused on the dependence of energy loss on peak magnetization Ip. The experiments, performed in a wide induction range (˜2×10-4 T≤Ip≤˜1.6 T), show that the ratio between rotational and alternating energy losses Whr/Wha is a monotonically decreasing function of Ip. A quantitative theoretical investigation is carried out through modeling of the magnetization process under rotating field and its relation to processes under alternating field. Three basic mechanisms of magnetization rotation are considered: linear combination of unidirectional hysteresis loops at low inductions (Rayleigh region), cyclic rearrangement of magnetic domains between different easy directions at intermediate inductions, and coherent spin rotation toward the approach to magnetic saturation. The ensuing predicted behavior of Whr/Wha is found to be in good agreement with the experiments performed in nonoriented low carbon steel and 3% FeSi laminations.

  2. Modeling of hysteresis loops by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Nehme, Z.; Labaye, Y.; Sayed Hassan, R.; Yaacoub, N.; Greneche, J. M.

    2015-12-01

    Recent advances in MC simulations of magnetic properties are rather devoted to non-interacting systems or ultrafast phenomena, while the modeling of quasi-static hysteresis loops of an assembly of spins with strong internal exchange interactions remains limited to specific cases. In the case of any assembly of magnetic moments, we propose MC simulations on the basis of a three dimensional classical Heisenberg model applied to an isolated magnetic slab involving first nearest neighbors exchange interactions and uniaxial anisotropy. Three different algorithms were successively implemented in order to simulate hysteresis loops: the classical free algorithm, the cone algorithm and a mixed one consisting of adding some global rotations. We focus particularly our study on the impact of varying the anisotropic constant parameter on the coercive field for different temperatures and algorithms. A study of the angular acceptation move distribution allows the dynamics of our simulations to be characterized. The results reveal that the coercive field is linearly related to the anisotropy providing that the algorithm and the numeric conditions are carefully chosen. In a general tendency, it is found that the efficiency of the simulation can be greatly enhanced by using the mixed algorithm that mimic the physics of collective behavior. Consequently, this study lead as to better quantified coercive fields measurements resulting from physical phenomena of complex magnetic (nano)architectures with different anisotropy contributions.

  3. Protein response to external electric fields: Relaxation, hysteresis, and echo

    SciTech Connect

    Xu, D.; Phillips, J.C.; Schulten, K.

    1996-07-18

    Dipole moments induced in proteins by external electric fields are studied by molecular dynamics simulations and described in terms of analytical models based on ensembles of Langevin oscillators and Fokker-Planck equations. We investigate through simulations of the protein bovine pancreatic trypsin inhibitor (BPTI) (1) the distribution p(M) of dipole moments as well as the dipole moment autocorrelation function C{sub M,M}(t) at thermal equilibrium, (2) the dielectric constant {epsilon}, (3) the dipole moment {Delta}M(t) induced by cyclic (piecewise linear or sinusoidally periodic in time) spatially homogeneous fields, demonstrating significant hysteresis behavior, and (4) the dipolar responce to a constant homogeneous field applied for about a picosecond. Through a comparison between an analytical model and simulations, we show that the dipolar response (4) can be described by a relaxation characterized by C{sub M,M}(t) in addition to a significant pulse-shaped component, termed the dipole echo. The hysteresis behaviour (3) under a weak external field is related to the equilibrium properties p(M), C{sub M,M}(t), and {epsilon}. In the case of electric fields arising through charge displacements in proteins, e.g., through electronic excitation or photoinduced electron transfer, concomitant dipolar responses in real proteins should resemble those reported here and should be observed by means of sub-picosecond spectroscopy. 53 refs., 17 figs.

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

    SciTech Connect

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

    2010-01-01

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

  5. Fractal growth of liquid crystals as a hysteresis phenomenon

    NASA Astrophysics Data System (ADS)

    Chan, Ho-Kei; Dierking, Ingo

    2006-03-01

    Fractal percolation growth of liquid crystal phases within a supercooled isotropic liquid medium has been observed in recent years. Notable examples include the B2 phase of `banana' mesogens [1] and the smectic C phase of a calamitic hydrogen-bonding liquid crystal [2]. Here we present a dynamical model that describes such fractal growth as well as the spherical growth conventionally observed for nematics and cholesterics. The essential idea is that the supercooled medium does not fully respond to the temperature quench immediately (hysteresis). Its fraction of space available for the phase transition only relaxes from 0 to 1 at some finite rate. Depending on the coupling between the relaxation and growth rates, the liquid crystal phase either grows as a percolation cluster of fractal dimension D 1.89 or approaches a spherical shape of Euclidean dimension D -> 2. The crossover behaviour from relatively slow to fast relaxation is thoroughly investigated. Possible causes of the hysteresis for fractal growth will be discussed. [1] I. Dierking, Liq. Cryst. Today 12(1), (2003), 1 [2] I. Dierking, Chan H. K., Culfaz F., McQuire S., Phys. Rev. E 70, (2004), 051701

  6. Wavenumber selection and hysteresis in nonlinear baroclinic flow

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung

    1995-01-01

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

  7. 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)].

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

    SciTech Connect

    Niemi, A.; Bodvarsson, G.S.

    1991-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Erta?, Mehmet; Keskin, Mustafa

    2015-08-01

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

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

    PubMed

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

    2010-09-01

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

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

    SciTech Connect

    Lin, H.J.; Chen, C.T.; Meigs, G.; Idzerda, Y.U.; Chaiken, A.; Prinz, G.A.; Ho, G.H.

    1993-09-07

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

  12. 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.

  13. Hysteresis of the Kuroshio penetrations into the South China Sea

    NASA Astrophysics Data System (ADS)

    Sheremet, V. A.

    2001-12-01

    An idealized problem of a western boundary current of Munk thickness LM flowing across a gap in a ridge is considered using a single-layer depth-averaged approach. When the gap (of width 2 a) is narrow, a <= 3.12 LM, viscous forces alone restrict penetration of the current through the gap. However, the gap is ``leaky'' in the linear case and some very weak flow still passes through. For larger gap width, the boundary current may leap across the gap due to inertia characterized by the Reynolds number Re, completely choking off water exchange between the two basins. For a >= 4.55 LM the flow may be in one of two regimes (penetrating or leaping) for the same parameters depending on previous evolution. The penetrating branch solutions become unsteady with eddies forming west of the gap between the two counter-flowing zonal jets. As the boundary current slowly accelerates, transition from the penetrating to leaping regime happens when the width of a zonal jet near the gap becomes comparable with a, implying the Reynolds number ReP ~= (a/LM)3. On the other hand as the boundary current slowly decelerates, the leaping regime persists while the meridional advection dominates the β -effect in a wiggle of the current core within the gap, implying that the leaping regime breaks at ReL ~= a/LM. Thus hysteresis occurs over the range of Reynolds numbers ReL < Re < ReP. An interesting application of this problem is to the Kuroshio current in Luzon Strait. The theory suggests that normally the Kuroshio can leap across Luzon Strait (LQP >= a). However, during periods when its strength is substantially reduced, it may penetrate into the South China Sea as a loop current. Thus multiple states and hysteresis are likely to occur. Because of the possible hysteresis, in analyzing the observational data, it is important to correlate the Kuroshio penetrations not only with the parameters describing the present state of the current, but also to take into account its history. For example, Farris and Wimbush (1996) found a relationship between the loop-current stage (derived from satellite infrared images) and the wind-stress history: the Kuroshio penetrations occur when the time-integrated strength of the northeast monsoon exceeds a threshold value. This is in qualitative agreement with the present theory in the sense that the penetrations occur when the Kuroshio is weakened by the monsoon blowing in the opposite direction.

  14. Ultralyophobic oxidized aluminum surfaces exhibiting negligible contact angle hysteresis.

    PubMed

    Hozumi, Atsushi; McCarthy, Thomas J

    2010-02-16

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

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

    SciTech Connect

    Meilikhov, E. Z. Farzetdinova, R. M.

    2013-01-15

    The phenomenon of nonrepeatability of successive remagnetization cycles in Co/M (M = Pt, Pd, Au) multilayer film structures is explained in the framework of the Kolmogorov crystallization model. It is shown that this model of phase transitions can be adapted so as to adequately describe the process of magnetic relaxation in the indicated systems with 'memory.' For this purpose, it is necessary to introduce some additional elements into the model, in particular, (i) to take into account the fact that every cycle starts from a state 'inherited' from the preceding cycle and (ii) to assume that the rate of growth of a new magnetic phase depends on the cycle number. This modified model provides a quite satisfactory qualitative and quantitative description of all features of successive magnetic relaxation cycles in the system under consideration, including the surprising phenomenon of cumulative growth of minor hysteresis loops.

  16. Bouc-Wen hysteresis model identification using Modified Firefly Algorithm

    NASA Astrophysics Data System (ADS)

    Zaman, Mohammad Asif; Sikder, Urmita

    2015-12-01

    The parameters of Bouc-Wen hysteresis model are identified using a Modified Firefly Algorithm. The proposed algorithm uses dynamic process control parameters to improve its performance. The algorithm is used to find the model parameter values that results in the least amount of error between a set of given data points and points obtained from the Bouc-Wen model. The performance of the algorithm is compared with the performance of conventional Firefly Algorithm, Genetic Algorithm and Differential Evolution algorithm in terms of convergence rate and accuracy. Compared to the other three optimization algorithms, the proposed algorithm is found to have good convergence rate with high degree of accuracy in identifying Bouc-Wen model parameters. Finally, the proposed method is used to find the Bouc-Wen model parameters from experimental data. The obtained model is found to be in good agreement with measured data.

  17. Hysteresis in coral reefs under macroalgal toxicity and overfishing.

    PubMed

    Bhattacharyya, Joydeb; Pal, Samares

    2015-03-01

    Macroalgae and corals compete for the available space in coral reef ecosystems.While herbivorous reef fish play a beneficial role in decreasing the growth of macroalgae, macroalgal toxicity and overfishing of herbivores leads to proliferation of macroalgae. The abundance of macroalgae changes the community structure towards a macroalgae-dominated reef ecosystem. We investigate coral-macroalgal phase shifts by means of a continuous time model in a food chain. Conditions for local asymptotic stability of steady states are derived. It is observed that in the presence of macroalgal toxicity and overfishing, the system exhibits hysteresis through saddle-node bifurcation and transcritical bifurcation. We examine the effects of time lags in the liberation of toxins by macroalgae and the recovery of algal turf in response to grazing of herbivores on macroalgae by performing equilibrium and stability analyses of delay-differential forms of the ODE model. Computer simulations have been carried out to illustrate the different analytical results. PMID:25708511

  18. 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.

  19. 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

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

    PubMed

    Yosia, Yosia; Ping, Shum; Chao, Lu

    2005-06-27

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

  1. Hysteresis of unsaturated hydromechanical properties of a silty soil

    USGS Publications Warehouse

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

    2013-01-01

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

  2. Hysteresis free carbon nanotube thin film transistors comprising hydrophobic dielectrics

    NASA Astrophysics Data System (ADS)

    Lefebvre, J.; Ding, J.; Li, Z.; Cheng, F.; Du, N.; Malenfant, P. R. L.

    2015-12-01

    We present two examples of carbon nanotube network thin film transistors with strongly hydrophobic dielectrics comprising either Teflon-AF or a poly(vinylphenol)/poly(methyl silsesquioxane) (PVP/pMSSQ) blend. In the absence of encapsulation, bottom gated transistors in air ambient show no hysteresis between forward and reverse gate sweep direction. Device threshold gate voltage and On-current present excellent time dependent stability even under dielectric stress. Furthermore, threshold gate voltage for hole conduction is negative upon device encapsulation with PVP/pMSSQ enabling much improved current On/Off ratio at 0 V. This work addresses two major challenges impeding solution based fabrication of relevant thin film transistors with printable single-walled carbon nanotube channels.

  3. Pressure effect on hysteresis in spin-crossover solid materials

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii; Ivashko, Victor; Dimian, Mihai

    2016-04-01

    A generalized microscopic Ising-like model is proposed to describe behavior of compressible spin-crossover solids with two states: low-spin and high-spin. The model was solved in mean-field approximation and shows hysteretic behavior at low energy difference between the states. We study the thermal transition between states under external hydrostatic pressure taking into account the changes in the volume of spin-crossover molecules in different states. Depending on the applied pressure, a spin-crossover system can have three types of behavior of molecular fraction in the high-spin state: hysteretic, second-order phase transition and no-phase transition. For the hysteretic regime, it is shown that the transition temperature under pressure is increased while the width of the hysteresis reduced.

  4. Creeping of minor hysteresis loops in Co thin films

    NASA Astrophysics Data System (ADS)

    Meilikhov, E. Z.; Farzetdinova, R. M.

    2012-09-01

    In the framework of the Kolmogorov crystallization model, the non-repeatability of successive remagnetization cycles for ultrathin Co/M (M = Pt, Pd, Au) films is considered. That model has been shown to be suitable for describing magnetic relaxation processes in such systems with a "memory." To this end some additional elements should be included in the model: it is necessary (i) to take into account that every cycle starts from the state left "heritably" by the preceding state and (ii) to suppose that the velocity of the new magnetic phase expansion depends on the cycle number. In the framework of such a model, we have succeeded to outline adequately (including quantitative description) all features of the successive magnetic relaxation cycles along with the astonishing effect of the cumulative growth of minor hysteresis loops.

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

    NASA Astrophysics Data System (ADS)

    Meilikhov, E. Z.; Farzetdinova, R. M.

    2013-01-01

    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.

  6. Causes and implications of colloid and microorganism retention hysteresis

    NASA Astrophysics Data System (ADS)

    Bradford, Scott A.; Kim, Hyunjung

    2012-09-01

    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 μm) and microorganisms (coliphage φX174 and E. coli D21g) under various transient solution chemistry conditions, and 360 μm Ottawa sand that was subject to different levels of cleaning, namely, a salt cleaning procedure that removed clay particles, and a salt + acid cleaning procedure that removed clay and reduced microscopic heterogeneities due to metal oxides and surface roughness. Comparison of results from the salt and salt + acid treated sand indicated that microscopic heterogeneity was a major contributor to colloid retention hysteresis. The influence of this heterogeneity increased with IS and decreasing colloid/microbe size on salt treated sand. These trends were not consistent with calculated mean interaction energies (the secondary minima), but could be explained by the size of the electrostatic zone of influence (ZOI) near microscopic heterogeneities. In particular, the depth of local minima in the interaction energy has been predicted to increase with a decrease in the ZOI when the colloid size and/or the Debye length decreased (IS increased). The adhesive interaction was therefore largely irreversible for smaller sized 0.1 μm CML colloids, whereas it was reversible for larger 1.1 μm CML colloids. Similarly, the larger E. coli D21g exhibited greater reversibility in retention than φX174. However, direct comparison of CML colloids and microbes was not possible due to differences in size, shape, and surface properties. Retention and release behavior of CML colloids on salt + acid treated sand was much more consistent with mean interaction energies due to reduction in microscopic heterogeneities.

  7. Causes and implications of colloid and microorganism retention hysteresis.

    PubMed

    Bradford, Scott A; Kim, Hyunjung

    2012-09-01

    Experiments were designed to better understand the causes and implications of colloid and microorganism retention hysteresis with transients in solution ionic strength (IS). Saturated packed column experiments were conducted using two sizes of carboxyl modified latex (CML) microspheres (0.1 and 1.1 ?m) and microorganisms (coliphage ?X174 and E. coli D21g) under various transient solution chemistry conditions, and 360 ?m Ottawa sand that was subject to different levels of cleaning, namely, a salt cleaning procedure that removed clay particles, and a salt+acid cleaning procedure that removed clay and reduced microscopic heterogeneities due to metal oxides and surface roughness. Comparison of results from the salt and salt+acid treated sand indicated that microscopic heterogeneity was a major contributor to colloid retention hysteresis. The influence of this heterogeneity increased with IS and decreasing colloid/microbe size on salt treated sand. These trends were not consistent with calculated mean interaction energies (the secondary minima), but could be explained by the size of the electrostatic zone of influence (ZOI) near microscopic heterogeneities. In particular, the depth of local minima in the interaction energy has been predicted to increase with a decrease in the ZOI when the colloid size and/or the Debye length decreased (IS increased). The adhesive interaction was therefore largely irreversible for smaller sized 0.1 ?m CML colloids, whereas it was reversible for larger 1.1 ?m CML colloids. Similarly, the larger E. coli D21g exhibited greater reversibility in retention than ?X174. However, direct comparison of CML colloids and microbes was not possible due to differences in size, shape, and surface properties. Retention and release behavior of CML colloids on salt+acid treated sand was much more consistent with mean interaction energies due to reduction in microscopic heterogeneities. PMID:22820488

  8. Finite element analysis of hysteresis effects in piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Simkovics, Reinhard; Landes, Hermann; Kaltenbacher, Manfred; Hoffelner, Johann; Lerch, Reinhard

    2000-06-01

    The design of ultrasonic transducers for high power applications, e.g. in medical therapy or production engineering, asks for effective computer aided design tools to analyze the occurring nonlinear effects. In this paper the finite-element-boundary-element package CAPA is presented that allows to model different types of electromechanical sensors and actuators. These transducers are based on various physical coupling effects, such as piezoelectricity or magneto- mechanical interactions. Their computer modeling requires the numerical solution of a multifield problem, such as coupled electric-mechanical fields or magnetic-mechanical fields as well as coupled mechanical-acoustic fields. With the reported software environment we are able to compute the dynamic behavior of electromechanical sensors and actuators by taking into account geometric nonlinearities, nonlinear wave propagation and ferroelectric as well as magnetic material nonlinearities. After a short introduction to the basic theory of the numerical calculation schemes, two practical examples will demonstrate the applicability of the numerical simulation tool. As a first example an ultrasonic thickness mode transducer consisting of a piezoceramic material used for high power ultrasound production is examined. Due to ferroelectric hysteresis, higher order harmonics can be detected in the actuators input current. Also in case of electrical and mechanical prestressing a resonance frequency shift occurs, caused by ferroelectric hysteresis and nonlinear dependencies of the material coefficients on electric field and mechanical stresses. As a second example, a power ultrasound transducer used in HIFU-therapy (high intensity focused ultrasound) is presented. Due to the compressibility and losses in the propagating fluid a nonlinear shock wave generation can be observed. For both examples a good agreement between numerical simulation and experimental data has been achieved.

  9. A theory of double hysteresis for ferroelectric crystals

    NASA Astrophysics Data System (ADS)

    Srivastava, N.; Weng, G. J.

    2006-03-01

    A ferroelectric crystal is known to exhibit the usual single hysteresis below its Curie point TC, but above this temperature its electric displacement D versus electric field E plot tends to form double loops. We first point out that there is a fundamental difference in the formation of double loops from the single one: the single loop is formed solely by polar reorientation, but in the double loops the right branch of its upper loop is formed by phase transition and only the left branch is formed by polar reorientation (the process is reversed for the lower loop). In this study we take the view that both cubic-->tetragonal phase transition and the polar reorientation of ferroelectric domain are thermodynamics-driving process and use this concept to develop a micromechanics-based thermodynamic model to simulate the double hysteresis behavior of the crystal. We first derive the thermodynamic driving force for both spontaneous polarization and domain switch at a given level of temperature, stress, electric field, and new domain concentration c1 and then establish the kinetic equations for domain growth. A dual-phase homogenization theory is then introduced to calculate the overall electric displacement and mechanical strain of the crystal. This approach differs from the classical Landau-Ginzburg-Devonshire theory in at least two significant aspects: (i) it is developed with a micromechanics-based thermodynamics principle, and (ii) it can provide the evolution of new domain concentration. The developed theory is applied to a BaTiO3 crystal. The calculated results show a single loop below its TC and double loops above it but with a diminishing width at higher temperature. Furthermore, the longitudinal strain ? vs E loop is found to exhibit the usual butterfly-shape relation below TC, but above it the loop shows a new, overlapping double-well picture. Good agreement with available test data is also observed.

  10. Large melting point hysteresis of Ge nanocrystals embedded inSiO2

    SciTech Connect

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

    2006-05-04

    The melting behavior of Ge nanocrystals embedded within SiO{sub 2} is evaluated using in situ transmission electron microscopy. The observed melting point hysteresis is large ({+-} 17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy.

  11. The intrinsic origin of hysteresis in MoS2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Shu, Jiapei; Wu, Gongtao; Guo, Yao; Liu, Bo; Wei, Xianlong; Chen, Qing

    2016-01-01

    We investigate the hysteresis and gate voltage stress effect in MoS2 field effect transistors (FETs). We observe that both the suspended and the SiO2-supported FETs have large hysteresis in their transfer curves under vacuum which cannot be attributed to the traps at the interface between the MoS2 and the SiO2 or in the SiO2 substrate or the gas adsorption/desorption effect. Our findings indicate that the hysteresis we observe comes from the MoS2 itself, revealing an intrinsic origin of the hysteresis besides some extrinsic factors. The fact that the FETs based on thinner MoS2 have larger hysteresis than that with thicker MoS2 suggests that the surface of MoS2 plays a key role in the hysteresis. The gate voltage sweep range, sweep direction, sweep time and loading history all affect the hysteresis observed in the transfer curves.We investigate the hysteresis and gate voltage stress effect in MoS2 field effect transistors (FETs). We observe that both the suspended and the SiO2-supported FETs have large hysteresis in their transfer curves under vacuum which cannot be attributed to the traps at the interface between the MoS2 and the SiO2 or in the SiO2 substrate or the gas adsorption/desorption effect. Our findings indicate that the hysteresis we observe comes from the MoS2 itself, revealing an intrinsic origin of the hysteresis besides some extrinsic factors. The fact that the FETs based on thinner MoS2 have larger hysteresis than that with thicker MoS2 suggests that the surface of MoS2 plays a key role in the hysteresis. The gate voltage sweep range, sweep direction, sweep time and loading history all affect the hysteresis observed in the transfer curves. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07336g

  12. Force, stiffness and hysteresis losses in high temperature superconducting bearings

    NASA Astrophysics Data System (ADS)

    Cansiz, Ahmet

    The vertical and horizontal forces and associated stiffnesses on a permanent magnet above a high- temperature superconductor were measured during vertical and horizontal traverses in zero-field cooling and in field cooling. In field cooling and zero field cooling, the vertical stiffness showed history dependence. In field cooling, the vertical stiffness was exactly two times greater than the lateral stiffness at each height, with an experimental error of less than 1%. A frozen image model was used to calculate the vertical and horizontal forces and stiffnesses, and reasonable agreement with the data occurred for vertical or horizontal movements of the permanent magnet less than several min from the field cooling position. We have investigated the effect of high temperature superconductor films deposited on substrates that are placed above bulk high temperature superconductors in an attempt to reduce rotational drag in superconducting bearings composed of a permanent magnet levitated above the film/bulk combination. According to the critical state model, hysteresis loss is inversely proportional to critical current density and because films typically have much higher critical current density than those of bulks, the film/bulk combination was expected to reduce rotational losses by at least one order of magnitude in the coefficient of friction, which in turn is a measure of the hysteresis losses. The experimental results showed that contrary to expectation, the rotational losses are increased by the film. Increasing losses from using a thin film turned attention to whether the thin film was shielding the varying magnetic field caused by the rotation of inhomogenous permanent magnet. For this reason, an ac coil was placed above the thin film HTS and the magnetic field on the other side of the film was measured with a pick-up coil. The experimental results showed that the thin film provides good shielding when the coil axis is perpendicular to the film surface whereas there is poor shielding when the coil is parallel to the surface. We have also investigated the vibration characteristic of the levitated permanent magnet over HTS for different cooling height and these properties were incorporated with vertical and lateral stiffnesses obtained in static measurements.

  13. Grain-damage hysteresis and plate tectonic states

    NASA Astrophysics Data System (ADS)

    Bercovici, David; Ricard, Yanick

    2016-04-01

    Shear localization in the lithosphere is an essential ingredient for understanding how and why plate tectonics is generated from mantle convection on terrestrial planets. The theoretical model for grain-damage and pinning in two-phase polycrystalline rocks provides a frame-work for understanding lithospheric shear weakening and plate-generation, and is consistent with laboratory and field observations of mylonites. Grain size evolves through the competition between coarsening, which drives grain-growth, and damage, which drives grain reduction. The interface between crystalline phases controls Zener pinning, which impedes grain growth. Damage to the interface enhances the Zener pinning effect, which then reduces grain-size, forcing the rheology into the grain-size-dependent diffusion creep regime. This process thus allows damage and rheological weakening to co-exist, providing a necessary positive self-weakening feedback. Moreover, because pinning inhibits grain-growth it promotes shear-zone longevity and plate-boundary inheritance. However, the suppression of interface damage at low interface curvature (wherein inter-grain mixing is inefficient and other energy sinks of deformational work are potentially more facile) causes a hysteresis effect, in which three possible equilibrium grain-sizes for a given stress coexist: (1) a stable, large-grain, weakly-deforming state, (2) a stable, small-grain, rapidly-deforming state analogous to ultramylonites, and (3) an unstable, intermediate grain-size state perhaps comparable to protomylonites. A comparison of the model to field data suggests that shear-localized zones of small-grain mylonites and ultra-mylonites exist at a lower stress than the co-existing large-grain porphyroclasts, rather than, as predicted by paleopiezometers or paleowattmeters, at a much higher stress; this interpretation of field data thus allows localization to relieve instead of accumulate stress. The model also predicts that a lithosphere that deforms at a given stress can acquire two stable deformation regimes indicative of plate-like flows, i.e., it permits the coexistence of both slowly deforming plate interiors, and rapidly deforming plate boundaries. Earth seems to exist squarely inside the hysteresis loop and thus can have coexisting deformation states, while Venus appears to straddle the end of the loop where only the weakly deforming branch exists.

  14. The intrinsic origin of hysteresis in MoS2 field effect transistors.

    PubMed

    Shu, Jiapei; Wu, Gongtao; Guo, Yao; Liu, Bo; Wei, Xianlong; Chen, Qing

    2016-01-28

    We investigate the hysteresis and gate voltage stress effect in MoS2 field effect transistors (FETs). We observe that both the suspended and the SiO2-supported FETs have large hysteresis in their transfer curves under vacuum which cannot be attributed to the traps at the interface between the MoS2 and the SiO2 or in the SiO2 substrate or the gas adsorption/desorption effect. Our findings indicate that the hysteresis we observe comes from the MoS2 itself, revealing an intrinsic origin of the hysteresis besides some extrinsic factors. The fact that the FETs based on thinner MoS2 have larger hysteresis than that with thicker MoS2 suggests that the surface of MoS2 plays a key role in the hysteresis. The gate voltage sweep range, sweep direction, sweep time and loading history all affect the hysteresis observed in the transfer curves. PMID:26782750

  15. The effect of contact angle hysteresis on droplet motion and collisions on superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Nilsson, Michael; Rothstein, Jonathan

    2010-11-01

    The effect of varying the contact angle hysteresis of a superhydrophobic surface on the characteristics and dynamics of water droplet motion and their subsequent collision are investigated using a high-speed camera. The surfaces are created by imparting random roughness to Teflon through sanding. With this technique, it is possible to create surfaces with similar advancing contact angles near 150 degrees, but with varying contact angle hysteresis. This talk will focus on a number of interesting experimental observations pertaining to drop dynamics along a surface with uniform hysteresis, drop motion along surfaces with transition zones from one hysteresis to another, and the collision of droplets on surfaces of uniform hysteresis. For single drop studies, gravity is used as the driving force, while the collision studies use pressurized air to propel one drop into the other. For the case of droplet collision, the effect of hysteresis, Weber number, and impact number on the maximum deformation of the drops, and the post-collision dynamics will be discussed. For the single droplet measurements, the resistance to motion will be characterized as well as the transition from rolling to sliding as a function of drop size, inclination angle, and hysteresis. Additionally, we will quantify the effect of surface transitions on the resulting motion, mixing, and deflection of the drops.

  16. 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

  17. The application of the load-stroke hysteresis technique for evaluating fatigue damage development

    SciTech Connect

    Baxter, T.; Reifsnider, K.L.

    1994-12-31

    A new experimental method was developed to measure hysteresis loss during a fatigue test from the load and stroke signals of a standard servo-hydraulic materials testing system. The method was used to characterize changes in properties and performance induced by long-term cyclic loading. Advantages of the load-stroke hysteresis measurement include: (1) contact with the specimen is not required, (2) the fatigue test is not interrupted for data collection, (3) the measured quantity (the hysteresis loop area) is directly related to the (damage) events that alter material properties and life, and (4) a quantitative measure of damage extent and development rate is obtained. The method was used to evaluate damage development during fatigue tests of polymeric composite laminates with unidirectional and angle-ply fiber orientations. The hysteresis loop measurements were used to identify the different stages of damage development and the different damage mechanisms (matrix cracking, delamination, and fiber fracture) in the material systems. The results from the hysteresis technique were correlated with conventional NDE methods such as dynamic signal analysis and specimen surface temperature measurements. It was found that the load-stroke hysteresis technique was especially sensitive to the fiber fracture, the most difficult type of damage process to interrogate in-situ. The hysteresis technique may provide a valuable method for predicting fatigue failure in composite specimens.

  18. Stress dependence of the hysteresis in single crystal NiTi alloys

    SciTech Connect

    Hamilton, R.F.; Sehitoglu, H.; Chumlyakov, Y.; Maier, H.J

    2004-06-21

    We demonstrate the variation in thermal hysteresis with increasing external stress for reversible martensitic transformations. The hysteresis was measured in temperature cycling experiments under external stress and also under pseudoleastic deformation conditions. To understand the role of composition and crystal orientation effects, the study included aged and solutionized Ti-50.1, Ti-50.4, Ti-50.8 and Ti-51.5at.%Ni in the [1 1 1], [0 0 1], [0 1 1], [0 1 2], and [1 2 3] orientations. Differential scanning calorimetry was used to characterize the thermal hysteresis resulting from thermal cycling under zero stress. The results show unequivocally that the thermal hysteresis expands with increasing external stress for aged and solutionized Ti-50.1at.%Ni and Ti-50.4at.%Ni alloys, while it contracts with increasing external stress for the higher Ni alloys with 50.8 and 51.5at.%Ni compositions. The growth of temperature hysteresis was from 20 deg. C to as high as 80 deg. C for the lower Ni alloys, while the contraction of the hysteresis was from 60 to 15 deg. C for the higher Ni alloys. The stress dependence of the hysteresis is rationalized considering dissipation of elastic strain energy due to relaxation of coherency strains at martensite-austenite interfaces. The role of precipitates and frictional work on transformation hysteresis is also clarified based on experiments on low and high Ni alloys with heterogeneous and homogenous precipitate structures respectively. A micro-mechanical model based on reversible thermodynamics was modified to account for plastic relaxation of coherent transforming interfaces, and the predictions account for the growing hysteresis with increasing external stress.

  19. 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.

  20. Solute concentration-dependent contact angle hysteresis and evaporation stains.

    PubMed

    Li, Yueh-Feng; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-07-01

    The presence of nonvolatile solutes in a liquid drop on a solid surface can affect the wetting properties. Depending on the surface-activity of the solutes, the extent of contact angle hysteresis (CAH) can vary with their concentration and the pattern of the evaporation stain is altered accordingly. In this work, four types of concentration-dependent CAH and evaporation stains are identified for a water drop containing polymeric additives on polycarbonate. For polymers without surface-activity such as dextran, advancing and receding contact angles (?a and ?r) are independent of solute concentrations, and a concentrated stain is observed in the vicinity of the drop center after complete evaporation. For polymers with weak surface-activity such as poly(ethylene glycol) (PEG), both ?a and ?r are decreased by solute addition, and the stain pattern varies with increasing PEG concentration, including a concentrated stain and a mountain-like island. For polymers with intermediate surface-activity such as sodium polystyrenesulfonate (NaPSS), ?a descends slightly, but ?r decreases significantly after the addition of a substantial amount of NaPSS, and a ring-like stain pattern is observed. Moreover, the size of the ring stain can be controlled by NaPSS concentration. For polymers with strong surface-activity such as poly(vinylpyrrolidone) (PVP), ?a remains essentially a constant, but ?r is significantly lowered after the addition of a small amount of PVP, and the typical ring-like stain is seen. PMID:24933206

  1. 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

  2. The Dynamic Characteristic and Hysteresis Effect of an Air Spring

    NASA Astrophysics Data System (ADS)

    Lcken, F.; Welsch, M.

    2015-02-01

    In many applications of vibration technology, especially in chassis, air springs present a common alternative to steel spring concepts. A design-independent and therefore universal approach is presented to describe the dynamic characteristic of such springs. Differential and constitutive equations based on energy balances of the enclosed volume and the mountings are given to describe the nonlinear and dynamic characteristics. Therefore all parameters can be estimated directly from physical and geometrical properties, without parameter fitting. The numerically solved equations fit very well to measurements of a passenger car air spring. In a second step a simplification of this model leads to a pure mechanical equation. While in principle the same parameters are used, just an empirical correction of the effective heat transfer coefficient is needed to handle some simplification on this topic. Finally, a linearization of this equation leads to an analogous mechanical model that can be assembled from two common spring- and one dashpot elements in a specific arrangement. This transfer into "mechanical language" enables a system description with a simple force-displacement law and a consideration of the nonobvious hysteresis and stiffness increase of an air spring from a mechanical point of view.

  3. Magnetization and Hysteresis of Dilute Magnetic-Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Skomski, Ralph; Balamurugan, B.; Sellmyer, D. J.

    2014-03-01

    Real-structure imperfections in dilute magnetic oxides tend to create small concentrations of local magnetic moments that are coupled by fairly long-range exchange interactions, mediated by p-electrons. The robustness of these interactions is caused by the strong overlap of the p orbitals, as contrasted to the much weaker interatomic exchange involving iron-series 3d electrons. The net exchange between defect moments can be positive or negative, which gives rise to spin structures with very small net moments. Similarly, the moments exhibit magnetocrystalline anisotropy, reinforced by electron hopping to and from 3d states and generally undergoing some random-anuisotropy averaging. Since the coercivity scales as 2K1/M and M is small, this creates pronounced and -- in thin films -- strongly anisotropic hysteresis loops. In finite systems with N moments, both K1 and M are reduced by a factor of order N1/2 due to random anisotropy and moment compensation, respectively, so that that typical coercivities are comparable to bulk magnets. Thermal activation readily randomizes the net moment of small oxide particles, so that the moment is easier to measure in compacted or aggregated particle ensembles. This research is supported by DOE (BES).

  4. On growth rate hysteresis and catastrophic crystal growth

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  5. Does Corneal Hysteresis Correlate with Endothelial Cell Density?

    PubMed Central

    Akova-Budak, Berna; K?van, Serta 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 11.51.7 mmHg and the mean CRF was 11.21.4 mmHg. Mean intraocular pressure was 15.32.3 mmHg. The mean endothelial cell count was 2754205 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

  6. 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

  7. Hysteresis and Stochastic Resonance in a Kinetic Ising System

    NASA Astrophysics Data System (ADS)

    Sides, S. W.; Ramos, R. A.; Rikvold, P. A.; Novotny, M. A.

    1996-03-01

    A nearest-neighbor kinetic Ising model has previously been used to model magnetization switching in nanoscale ferromagnets in a static external field.(H.L. Richards, S.W. Sides, P.A. Rikvold, and M.A. Novotny, J. Mag. Mag. Materials 150), 37 (1995). We extend this work to study the magnetization response in an oscillating field. We compute the power spectral density and the probability distributions for the period-averaged magnetization and the hysteresis loop area using Monte Carlo simulations. We also investigate the residence time distributions, which provide a sensitive probe for stochastic resonance.( L. Gammaitoni, F. Marchesoni, and S. Santucci, Phys. Rev. Lett. 74), 1052 (1994). These quantities are all analyzed within the framework of distinct deterministic and stochastic decay modes,( P.A. Rikvold, H. Tomita, S. Miyashita, and S.W. Sides, Phys. Rev. E 49), 5080 (1994). which predicts finite-size effects that may be observable in nanometer-sized particles.^1 Supported in part by FSU-MARTECH, by FSU-SCRI under DOE Contract, and by NSF Grants No. DMR-9315969 and DMR-9520325.

  8. Thermodynamic Model for Contact Angle Hysteresis on Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Raj, Rishi; Enright, Ryan; Adera, Solomon; Wang, Evelyn

    2013-03-01

    Wettability of solid surfaces can be tuned by introducing roughness. This effect has been explained by Wenzel, whereby texturing increases the degree of hydrophilicity (hydrophobicity) of an intrinsic hydrophilic (hydrophobic) flat surface. However, experimentally observed dynamic contact angles deviate significantly from those predicted by Wenzel equation. In this work, we demonstrate that local contact line distortion and pinning on structured surfaces is the key aspect that needs to be accounted for in the dynamic droplet models. Contact line distortions and pinning were visualized and analyzed to develop a thermodynamic model for contact angle hysteresis on rough surfaces. The developed model showed good agreement with the experimental advancing and receding contact angles, both at low and high solid fractions. The thermodynamic model was further extended to demonstrate its capability to capture droplet shape evolution during liquid addition and removal in our experiments and those in literature. The understanding developed in this study offers new insight extending the fundamental understanding of solid-liquid interactions required for the design of advanced functional coatings for microfluidics, biological, manufacturing, and heat transfer applications. Previously: Device Research Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology

  9. Hysteresis-based analysis of overland metal transport

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

  10. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Surbhi; Tomar, Monika; Gupta, Vinay

    2015-03-01

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

  11. Hysteresis of ligand binding in CNGA2 ion channels

    PubMed Central

    Nache, Vasilica; Eick, Thomas; Schulz, Eckhard; Schmauder, Ralf; Benndorf, Klaus

    2013-01-01

    Tetrameric cyclic nucleotide-gated (CNG) channels mediate receptor potentials in olfaction and vision. The channels are activated by the binding of cyclic nucleotides to a binding domain embedded in the C terminus of each subunit. Here using a fluorescent cGMP derivative (fcGMP), we show for homotetrameric CNGA2 channels that ligand unbinding is ~50 times faster at saturating than at subsaturating fcGMP. Analysis with complex Markovian models reveals two pathways for ligand unbinding; the partially liganded open channel unbinds its ligands from closed states only, whereas the fully liganded channel reaches a different open state from which it unbinds all four ligands rapidly. Consequently, the transition pathways for ligand binding and activation of a fully liganded CNGA2 channel differ from that of ligand unbinding and deactivation, resulting in pronounced hysteresis of the gating mechanism. This concentration-dependent gating mechanism allows the channels to respond to changes in the cyclic nucleotide concentration with different kinetics. PMID:24287615

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

    SciTech Connect

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

    2014-04-15

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

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  15. 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.

  16. Thermal hysteresis caused by non-equilibrium antifreeze activity of poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Inada, Takaaki; Lu, Shu-Shen

    2004-08-01

    Thermal hysteresis is often taken as the primary manifestation of antifreeze activity of biological non-equilibrium antifreezes, such as antifreeze proteins and antifreeze glycoproteins. Here we report evidence of the thermal hysteresis caused by poly(vinyl alcohol) (PVA). Similar to biological non-equilibrium antifreezes, PVA molecules stopped the growth of ice in the melt at temperatures even below the melting temperature of ice, although PVA exhibited very slight thermal hysteresis compared with most known biological antifreezes. The crystal habit of ice in the melt in the presence of PVA indicated that PVA molecules affected specific planes of the ice crystal.

  17. Experimental investigations of boiling heat transfer hysteresis on sintered, metal - Fibrous, porous structures

    SciTech Connect

    Wojcik, Tadeusz Michal

    2009-03-15

    The paper discusses the results of experimental investigations of boiling heat transfer on sintered metal capillary-porous coverings of the heating surface. The experiments were carried out for copper, fibrous structures with stochastic distribution of pores. The boiling curves were obtained at the increasing and decreasing of the heat flux, which made it possible to detect the hysteresis phenomena of different types. The classification of the hysteresis phenomena, based on the author's own results and those available in the literature, was provided. Three types of hysteresis were observed. The physical mechanism of the phenomenon was presented and the features characteristic of boiling in the porous covering were taken into account. (author)

  18. The thermal hysteresis activity of the type I antifreeze protein: A statistical mechanics model

    NASA Astrophysics Data System (ADS)

    Li, Li-Fen; Liang, X. X.; Li, Q. Z.

    2009-04-01

    Based on the adsorption-inhibition theory, a statistical mechanics model is proposed to investigate the thermal hysteresis activity of the type I antifreeze protein. The thermal hysteresis activity is evaluated by determining the AFP molecule coverage rate on the ice surface and the Gibbs function of the system. As examples, the calculated results for the thermal hysteresis temperatures of AFP9, HPLC-6(TTTT) and AAAA2kE as functions of the concentration of the AFP solution are obtained and discussed. The theoretical results are in agreement with the experimental data.

  19. Self-induced hysteresis for nonlinear acoustic waves in cracked material.

    PubMed

    Moussatov, Alexei; Gusev, Vitalyi; Castagnde, Bernard

    2003-03-28

    A new phenomenon of self-induced hysteresis has been observed in the interaction of bulk acoustic waves with a cracked solid. It consists in a hysteretic behavior of material nonlinearity as a function of the incident pump wave amplitude. Hysteresis manifests itself in the self-action of the monochromatic pump wave and in the excitation of its superharmonics and of its subharmonics. The proposed theoretical models attribute the phenomenon to hysteresis in transition of the acoustically forced oscillation of cracks from a nonclapping regime to a regime of clapping contacts. PMID:12688875

  20. Self-Induced Hysteresis for Nonlinear Acoustic Waves in Cracked Material

    NASA Astrophysics Data System (ADS)

    Moussatov, Alexei; Gusev, Vitalyi; Castagnde, Bernard

    2003-03-01

    A new phenomenon of self-induced hysteresis has been observed in the interaction of bulk acoustic waves with a cracked solid. It consists in a hysteretic behavior of material nonlinearity as a function of the incident pump wave amplitude. Hysteresis manifests itself in the self-action of the monochromatic pump wave and in the excitation of its superharmonics and of its subharmonics. The proposed theoretical models attribute the phenomenon to hysteresis in transition of the acoustically forced oscillation of cracks from a nonclapping regime to a regime of clapping contacts.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  2. Tunable high magnetic field thermal hysteresis for exchange-coupled double layers

    NASA Astrophysics Data System (ADS)

    Demirtas, S.; Koymen, A. R.

    2007-02-01

    Two types of tunable thermal hysteresis are observed for the first time in exchange-coupled double layer (ECDL) structures. For low external magnetic fields, ECDLs show one compensation temperature where the measurement of the magnetization as a function of temperature displays a bow-tie shape. For high fields a new type of tunable thermal hysteresis is observed due to an interface wall created between the layers where the ECDL shows two different compensation temperatures. The widths of both forms of thermal hysteresis are tunable with a change in external magnetic field.

  3. Temperature-dependent gate-swing hysteresis of pentacene thin film transistors

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon; Lin, Yu-Cheng

    2014-10-01

    The temperature-dependent hysteresis-type transfer characteristics of pentacene-based organic thin film transistors (OTFTs) were researched. The temperature-dependent transfer characteristics exhibit hopping conduction behavior. The fitting data for the temperature-dependent off-to-on and on-to-off transfer characteristics of OTFTs demonstrate that the hopping distance (ah) and the barrier height for hopping (qϕt) control the carrier flow, resulting in the hysteresis-type transfer characteristics of OTFTs. The hopping model gives an explanation of the gate-swing hysteresis and the roles played by qϕt and ah.

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

    NASA Astrophysics Data System (ADS)

    Zvizdi?, D.; estan, D.

    2013-09-01

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

  5. Effects of grain size, hardness, and stress on the magnetic hysteresis loops of ferromagnetic steels

    NASA Astrophysics Data System (ADS)

    Kwun, H.; Burkhardt, G. L.

    1987-02-01

    Effects of grain size, hardness, and stress on the magnetic hysteresis loops of AISI 410 stainless steel and SAE 4340 steel specimens were investigated experimentally. It was observed that both hardness and stress significantly influenced the hysteresis loops, while the grain size had a minimal effect. For each material, the mechanically harder specimen was more difficult to magnetize. Upon application of uniaxial stress, the magnetic induction increased under tension and decreased under compression, with the sides of the hysteresis loops becoming inclined more toward the vertical axis under tension and the horizontal axis under compression. For each material, the effects of stress on the hysteresis loops were greater for the mechanically softer specimen and exhibited an inverse relationship to the hardness. The effects of stress were not dependent on grain size.

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

    PubMed

    Mettu, Srinivas; Chaudhury, Manoj K

    2011-08-16

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

  7. Origin of hysteresis in resistive switching in magnetite is Joule heating

    NASA Astrophysics Data System (ADS)

    Fursina, A. A.; Sofin, R. G. S.; Shvets, I. V.; Natelson, D.

    2009-06-01

    In many transition-metal oxides the electrical resistance is observed to undergo dramatic changes induced by large biases. In magnetite, Fe3O4 , below the Verwey temperature, an electric-field-driven transition to a state of lower resistance was recently found, with hysteretic current-voltage response. We report the results of pulsed electrical conduction measurements in epitaxial magnetite thin films. We show that while the high- to low-resistance transition is driven by electric field, the hysteresis observed in I-V curves results from Joule heating in the low-resistance state. The shape of the hysteresis loop depends on pulse parameters and reduces to a hysteresis-free “jump” of the current provided thermal relaxation is rapid compared to the time between voltage pulses. A simple relaxation-time thermal model is proposed that captures the essentials of the hysteresis mechanism.

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

    SciTech Connect

    Kocakaplan, Yusuf; Keskin, Mustafa

    2014-09-07

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

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

    NASA Astrophysics Data System (ADS)

    Alatawneh, Natheer; Pillay, Pragasen

    2016-01-01

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

  10. 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.

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

    PubMed Central

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

    2014-01-01

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

  12. Ac hysteresis loop measurement of stator-tooth in induction motor

    SciTech Connect

    Son, D.

    1999-09-01

    The properties of ac hysteresis loop of a stator tooth in a 5 hp induction motor was measured and analyzed. The load increase on the motor decreased magnetic induction, however increase the minor hysteresis loops in the high induction region. This effect caused increase in the core loss. Depending on condition of the motor, the core loss of the stator tooth can be 50% greater than the core loss under sinusoidal magnetic induction waveform.

  13. Hysteresis phenomenon of the field emission from carbon nanotube/polymer nanocomposite

    NASA Astrophysics Data System (ADS)

    Filippov, S. V.; Popov, E. O.; Kolosko, A. G.; Romanov, P. A.

    2015-11-01

    Using the high voltage scanning method and the technique of multichannel recording and processing of field emission (FE) characteristics in real time mode we found out some subtle effects on current voltage characteristics (IVC) of the multi-tip field emitters. We observed the direct and reverse hysteresis simultaneously in the same field emission experiment. Dependence of the form of IVC hysteresis on time of high voltage scanning was observed.

  14. Measurements of the hysteresis in unzipping and rezipping double-stranded DNA

    NASA Astrophysics Data System (ADS)

    Hatch, K.; Danilowicz, C.; Coljee, V.; Prentiss, M.

    2007-05-01

    Complete unzipping and rezipping of ? -phage double-stranded DNA is achieved by applying a constant force. A strong hysteresis is observed at all tested time scales and temperatures. Hysteresis also occurs for partial unzipping, indicating stability for the partially open state over a force range of 2- 5pN . Results are compared to nearest-neighbor model simulations, and reasonable agreement is found.

  15. Mercury Porosimetry: Contact Angle Hysteresis of Materials with Controlled Pore Structure.

    PubMed

    Salmas, Constantinos; Androutsopoulos, George

    2001-07-01

    Mercury Porosimetry (MP) hysteresis is a commonly observed phenomenon in which mercury retention disguises further the overall hysteresis picture. This article introduces a new interpretation of the MP hysteresis based on the combined effect of pore structure networking and mercury contact angle variation occurring between the mercury penetration and retraction operations. To distinguish the contribution of each factor the following investigations were carried out. Nitrogen sorption (NP) and MP experiments were performed on samples of an anodic aluminum membrane and the results were interpreted in terms of the Corrugated Pore Structure Model (CPSM), i.e., CPSM-Nitrogen and CPSM-Mercury models, respectively. The simulation of the observed hysteresis data using the CPSM model enabled the evaluation of an identical for the two methods intrinsic pore size distribution (PSD) and cumulative surface area in perfect agreement with the respective BET value. Additionally, the CPSM analysis of data resulted in the evaluation of mercury contact angles, i.e., ?(p)=143 degrees and ?(r)=101.7 degrees for the MP penetration and retraction branches of the hysteresis loop, respectively. Moreover, CPSM-Mercury simulations of literature MP hysteresis data, valid for controlled-pore glasses and nuclepore membranes, led to the evaluation of contact angles, i.e., glasses: ?(p)=143 degrees, ?(r)=100.5-107.5 degrees and nuclepore: ?(p)=143 degrees, ?(r)=118- 121 degrees. The latter values are comparable with relevant literature data and approximate those determined for the anodic aluminum membrane. The CPSM model employed herein proved to be a flexible and reliable model for simulating the pertinent hysteresis loops by combining pore networking and contact angle hysteresis phenomena. Copyright 2001 Academic Press. PMID:11397062

  16. A computationally effective dynamic hysteresis model taking into account skin effect in magnetic laminations

    NASA Astrophysics Data System (ADS)

    de la Barrire, O.; Ragusa, C.; Appino, C.; Fiorillo, F.; LoBue, M.; Mazaleyrat, F.

    2014-02-01

    We propose a simplified dynamic hysteresis model for the prediction of magnetization behavior of electrical steel up to high frequencies, taking into account the skin effect. This model has the advantage of predicting the hysteresis loop and loss behavior versus frequency with the same accuracy provided by the Dynamic Preisach Model with a largely reduced computational burden. It is here compared to experimental results obtained in Fe-Si laminations under sinusoidal flux up to 2 kHz.

  17. Hysteresis responses of evapotranspiration to meteorological factors at a diel timescale: patterns and causes.

    PubMed

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

    2014-01-01

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

  18. Effect of hysteresis on the stability of an embankment under transient seepage

    NASA Astrophysics Data System (ADS)

    Liu, K.; Vardon, P. J.; Arnold, P.; Hicks, M. A.

    2015-09-01

    Hysteresis is a well-known phenomenon that exists in the soil water retention behaviour of unsaturated soils. However, there is little research on the effects of hysteresis on slope stability. If included in slope stability analyses, commonly the suction in the unsaturated zone is taken as non-hysteretic. In this paper, the authors investigate the effect of hysteresis on the stability of an embankment under transient seepage. A scenario of water level fluctuation has been assessed, in which a cyclic external water level fluctuates between a low and high level. It was found that the factor of safety (FOS), the volumetric water content and the suction in the unsaturated zone are significantly affected by hysteresis. It was also found that, when the period of water level fluctuation in one cycle is relatively small, there is little difference in the FOS between the hysteretic case and non-hysteretic case. However, when the period exceeds a certain threshold value, significant differences between these two cases can be observed. Compared to the case in which hysteresis is considered, the FOS is higher in the case which does not consider hysteresis. This suggests that the non-hysteretic case may overestimate slope stability, leading to a potentially dangerous situation. Moreover, the period under which there emerge large differences between the hysteretic and non-hysteretic case is strongly related to the magnitude of hydraulic conductivity and the period of the cyclic water level fluctuation.

  19. Hysteresis Effects and Strain-Induced Homogeneity Effects in Base Metal Thermocouples

    NASA Astrophysics Data System (ADS)

    Pavlasek, P.; Elliott, C. J.; Pearce, J. V.; Duris, S.; Palencar, R.; Koval, M.; Machin, G.

    2015-03-01

    Thermocouples are used in a wide variety of industrial applications in which they play an important role for temperature control and monitoring. Wire inhomogeneity and hysteresis effects are major sources of uncertainty in thermocouple measurements. To efficiently mitigate these effects, it is first necessary to explore the impact of strain-induced inhomogeneities and hysteresis, and their contribution to the uncertainty. This article investigates homogeneity and hysteresis effects in Types N and K mineral-insulated metal-sheathed (MIMS) thermocouples. Homogeneity of thermocouple wires is known to change when mechanical strain is experienced by the thermoelements. To test this influence, bends of increasingly small radii, typical in industrial applications, were made to a number of thermocouples with different sheath diameters. The change in homogeneity was determined through controlled immersion of the thermocouple into an isothermal liquid oil bath at and was found to be very small at for Type K thermocouples, with no measureable change in Type N thermocouples found. An experiment to determine the hysteresis effect in thermocouples was performed on swaged, MIMS Type N and Type K thermocouples, in the temperature range from to . The hysteresis measurements presented simulate the conditions that thermocouples may be exposed to in industrial applications through continuous cycling over 136 h. During this exposure, a characteristic drift from the reference function has been observed but no considerable difference between the heating and cooling measurements was measureable. The measured differences were within the measurement uncertainties; therefore, no hysteresis was observed.

  20. Study of hysteresis behavior in reactive sputtering of cylindrical magnetron plasma

    NASA Astrophysics Data System (ADS)

    Kakati, H.; M. Borah, S.

    2015-12-01

    In order to make sufficient use of reactive cylindrical magnetron plasma for depositing compound thin films, it is necessary to characterize the hysteresis behavior of the discharge. Cylindrical magnetron plasmas with different targets namely titanium and aluminium are studied in an argon/oxygen and an argon/nitrogen gas environment respectively. The aluminium and titanium emission lines are observed at different flows of reactive gases. The emission intensity is found to decrease with the increase of the reactive gas flow rate. The hysteresis behavior of reactive cylindrical magnetron plasma is studied by determining the variation of discharge voltage with increasing and then reducing the flow rate of reactive gas, while keeping the discharge current constant at 100 mA. Distinct hysteresis is found to be formed for the aluminium target and reactive gas oxygen. For aluminium/nitrogen, titanium/oxygen and titanium/nitrogen, there is also an indication of the formation of hysteresis; however, the characteristics of variation from metallic to reactive mode are different in different cases. The hysteresis behaviors are different for aluminium and titanium targets with the oxygen and nitrogen reactive gases, signifying the difference in reactivity between them. The effects of the argon flow rate and magnetic field on the hysteresis are studied and explained. Project supported by the Department of Science and Technology, Government of India and Council of Scientific and Industrial Research, India.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2016-02-01

    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.

  6. 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.

  7. Hysteresis loop behaviors of ferroelectric thin films: A Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    M. Bedoya-Hincapié, C.; H. Ortiz-Álvarez, H.; Restrepo-Parra, E.; J. Olaya-Flórez, J.; E. Alfonso, J.

    2015-11-01

    The ferroelectric response of bismuth titanate Bi4Ti3O12 (BIT) thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms: the electric field applied in the z direction, the nearest dipole–dipole interaction in the transversal (x–y) direction, and the nearest dipole–dipole interaction in the direction perpendicular to the thin film (the z axis). In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response. Project sponsored by the research departments of the Universidad Nacional de Colombia DIMA and DIB under Project 201010018227-“Crecimiento y caracterización eléctrica y estructural de películas delgadas de BixTiyOz producidas mediante Magnetrón Sputtering” and Project 12920-“Desarrollo teóricoexperimental de nanoestructuras basadas en Bismuto y materiales similares” and “Bisnano Project.”

  8. Hysteresis model and statistical interpretation of energy losses in non-oriented steels

    NASA Astrophysics Data System (ADS)

    Mănescu (Păltânea), Veronica; Păltânea, Gheorghe; Gavrilă, Horia

    2016-04-01

    In this paper the hysteresis energy losses in two non-oriented industrial steels (M400-65A and M800-65A) were determined, by means of an efficient classical Preisach model, which is based on the Pescetti-Biorci method for the identification of the Preisach density. The excess and the total energy losses were also determined, using a statistical framework, based on magnetic object theory. The hysteresis energy losses, in a non-oriented steel alloy, depend on the peak magnetic polarization and they can be computed using a Preisach model, due to the fact that in these materials there is a direct link between the elementary rectangular loops and the discontinuous character of the magnetization process (Barkhausen jumps). To determine the Preisach density it was necessary to measure the normal magnetization curve and the saturation hysteresis cycle. A system of equations was deduced and the Preisach density was calculated for a magnetic polarization of 1.5 T; then the hysteresis cycle was reconstructed. Using the same pattern for the Preisach distribution, it was computed the hysteresis cycle for 1 T. The classical losses were calculated using a well known formula and the excess energy losses were determined by means of the magnetic object theory. The total energy losses were mathematically reconstructed and compared with those, measured experimentally.

  9. 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.

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

    SciTech Connect

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

    2004-03-12

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

  11. 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

  12. Relationship between Wetting Hysteresis and Contact Time of a Bouncing Droplet on Hydrophobic Surfaces.

    PubMed

    Shen, Yizhou; Tao, Jie; Tao, Haijun; Chen, Shanlong; Pan, Lei; Wang, Tao

    2015-09-23

    The contact time of impacting water droplets on superhydrophobic surfaces directly reflects the extent of thermal and energy conversions between the water droplet and the surface, which is also considered to be crucial to the practical applications. The purpose of this study was to reveal the relationship between the contact time and the wetting hysteresis. We designed and fabricated six classes of surfaces with different extent of hydrophobicity through modifying the microscale/nanoscale hierarchical textured titanium surfaces with 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and we filmed the contact process of the water droplet impacting on these surfaces using a high-speed camera. It can be concluded that wetting hysteresis played a significant role in determining how long the impacting water droplet can bounce off the surface, based on the interfacial wetting mechanism and the work done against the resistance force generated by contact angle hysteresis during the dynamic process. PMID:26331793

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

    SciTech Connect

    Matthews, G.P.; Ridgway, C.J.; Spearing, M.C.

    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.

  14. Determining hysteresis thresholds for edge detection by combining the advantages and disadvantages of thresholding methods.

    PubMed

    Medina-Carnicer, R; Carmona-Poyato, A; Muoz-Salinas, R; Madrid-Cuevas, F J

    2010-01-01

    Hysteresis is an important technique for edge detection, but the unsupervised determination of its parameters is not an easy problem. In this paper, we propose a method for unsupervised determination of hysteresis thresholds using the advantages and disadvantages of two thresholding methods. The basic idea of our method is to look for the best hysteresis thresholds in a set of candidates. First, the method finds a subset and a overset of the unknown edge points set. Then, it determines the best edge map with the measure chi(2). Compared with a general method to determine the parameters of an edge detector, our method performs well and is less computationally complex. The basic idea of our method can be generalized to other pattern recognition problems. PMID:19783504

  15. Low voltage, hysteresis free, and high mobility transistors from all-inorganic colloidal nanocrystals.

    PubMed

    Chung, Dae Sung; Lee, Jong-Soo; Huang, Jing; Nag, Angshuman; Ithurria, Sandrine; Talapin, Dmitri V

    2012-04-11

    High-mobility solution-processed all-inorganic solid state nanocrystal (NC) transistors with low operation voltage and near-zero hysteresis are demonstrated using high-capacitance ZrO(x) and hydroxyl-free Cytop gate dielectric materials. The use of inorganic capping ligands (In(2)Se(4)(2-) and S(2-)) allowed us to achieve high electron mobility in the arrays of solution-processed CdSe nanocrystals. We also studied the hysteresis behavior and switching speed of NC-based field effect devices. Collectively, these analyses helped to understand the charge transport and trapping mechanisms in all-inorganic NCs arrays. Finally, we have examined the rapid thermal annealing as an approach toward high-performance solution-processed NCs-based devices and demonstrated transistor operation with mobility above 30 cm(2)/(V s) without compromising low operation voltage and hysteresis. PMID:22385132

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

    NASA Astrophysics Data System (ADS)

    Huang, Haiming; Chou, Wusheng; Zhang, Zuojiang

    2015-12-01

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

  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. Efficient hysteresis loop simulations of nanoparticle assemblies beyond the uniaxial anisotropy

    NASA Astrophysics Data System (ADS)

    Tamion, Alexandre; Bonet, Edgar; Tournus, Florent; Raufast, Ccile; Hillion, Arnaud; Gaier, Oksana; Dupuis, Vronique

    2012-04-01

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

  19. A two-state hysteresis model from high-dimensional friction

    PubMed Central

    Biswas, Saurabh; Chatterjee, Anindya

    2015-01-01

    In prior work (Biswas & Chatterjee 2014 Proc. R. Soc. A 470, 20130817 (doi:10.1098/rspa.2013.0817)), we developed a six-state hysteresis model from a high-dimensional frictional system. Here, we use a more intuitively appealing frictional system that resembles one studied earlier by Iwan. The basis functions now have simple analytical description. The number of states required decreases further, from six to the theoretical minimum of two. The number of fitted parameters is reduced by an order of magnitude, to just six. An explicit and faster numerical solution method is developed. Parameter fitting to match different specified hysteresis loops is demonstrated. In summary, a new two-state model of hysteresis is presented that is ready for practical implementation. Essential Matlab code is provided. PMID:26587279

  20. A Ni-Cd battery model considering state of charge and hysteresis effects

    NASA Astrophysics Data System (ADS)

    García-Plaza, M.; Serrano-Jiménez, D.; Eloy-García Carrasco, J.; Alonso-Martínez, J.

    2015-02-01

    This paper introduces an electrical battery model. Based on a Thévenin circuit with two RC parallel branches, it includes an ampère-hour counting method to estimate the state of charge (SOC) and a novel model for the hysteresis. The presented model can consider variations in its parameters under changes in all of its internal and external variables, although only SOC and hysteresis are considered. Hysteresis consideration does not only allow distinguishing the parameters during charging and discharging, but also during transients between them. The model was designed to be capable of being implemented in online and offline systems. Finally the proposed model was validated for a single Ni-Cd cell, characterized by current interruption method, in an offline system. The validation was also extended to a stack of 210 cells of the same technology.

  1. 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.

  2. Hysteresis in the capillary-sorption water potential as dependent on the soil water content

    NASA Astrophysics Data System (ADS)

    Shvarov, A. P.; Koreneva, E. A.

    2008-10-01

    The capillary-sorption hysteresis within the entire range of the soil water contents has been studied in zonal soil types of the European part of Russia. The degree of hysteresis in the sorption and capillary-sorption ranges has been estimated. The main factors of the hysteresis are established. In the area of water sorption, this phenomenon is due to different wetting angles in the course of the soil wetting-drying cycles because of the heterogeneous hydrophilic and hydrophobic surfaces of the soil particles. In the area of capillary moistening, the pore-size distribution as a function of the soil macro-and microstructure is important, as this characteristic is closely related to shrinking and swelling processes.

  3. Adaptive neural control for a class of nonlinear time-varying delay systems with unknown hysteresis.

    PubMed

    Liu, Zhi; Lai, Guanyu; Zhang, Yun; Chen, Xin; Chen, Chun Lung Philip

    2014-12-01

    This paper investigates the fusion of unknown direction hysteresis model with adaptive neural control techniques in face of time-delayed continuous time nonlinear systems without strict-feedback form. Compared with previous works on the hysteresis phenomenon, the direction of the modified Bouc-Wen hysteresis model investigated in the literature is unknown. To reduce the computation burden in adaptation mechanism, an optimized adaptation method is successfully applied to the control design. Based on the Lyapunov-Krasovskii method, two neural-network-based adaptive control algorithms are constructed to guarantee that all the system states and adaptive parameters remain bounded, and the tracking error converges to an adjustable neighborhood of the origin. In final, some numerical examples are provided to validate the effectiveness of the proposed control methods. PMID:25420237

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Ersin, Kantar

    2015-10-01

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

  6. 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.

  7. A two-state hysteresis model from high-dimensional friction.

    PubMed

    Biswas, Saurabh; Chatterjee, Anindya

    2015-07-01

    In prior work (Biswas & Chatterjee 2014 Proc. R. Soc. A 470, 20130817 (doi:10.1098/rspa.2013.0817)), we developed a six-state hysteresis model from a high-dimensional frictional system. Here, we use a more intuitively appealing frictional system that resembles one studied earlier by Iwan. The basis functions now have simple analytical description. The number of states required decreases further, from six to the theoretical minimum of two. The number of fitted parameters is reduced by an order of magnitude, to just six. An explicit and faster numerical solution method is developed. Parameter fitting to match different specified hysteresis loops is demonstrated. In summary, a new two-state model of hysteresis is presented that is ready for practical implementation. Essential Matlab code is provided. PMID:26587279

  8. Technical Note: Testing an improved index for analysing storm discharge-concentration hysteresis

    NASA Astrophysics Data System (ADS)

    Lloyd, C. E. M.; Freer, J. E.; Johnes, P. J.; Collins, A. L.

    2016-02-01

    Analysis of hydrochemical behaviour during storm events can provide new insights into the process controls on nutrient transport in catchments. The examination of storm behaviours using hysteresis analysis has increased in recent years, partly due to the increased availability of high temporal resolution data sets for discharge and water quality parameters. A number of these analyses involve the use of an index to describe the characteristics of a hysteresis loop in order to compare storm behaviours both within and between catchments. This technical note reviews the methods for calculation of the hysteresis index (HI) and explores a new more effective methodology. Each method is systematically tested and the impact of the chosen calculation on the results is examined. Recommendations are made regarding the most effective method of calculating a HI which can be used for comparing data between storms and between different water quality parameters and catchments.

  9. Influence of hysteresis on groundwater wave dynamics in an unconfined aquifer with a sloping boundary

    NASA Astrophysics Data System (ADS)

    Shoushtari, Seyed Mohammad Hossein Jazayeri; Cartwright, Nick; Perrochet, Pierre; Nielsen, Peter

    2015-12-01

    In this paper, the influence of hysteresis on water table dynamics in an unconfined aquifer was examined using a numerical model to solve Richards' unsaturated flow equation. The model was subject to simple harmonic forcing across a sloping boundary with a seepage face boundary condition. Time series from both hysteretic and non-hysteretic models were subject to harmonic analysis to extract the amplitude and phase profiles for comparison with existing sand flume data (Cartwright et al., 2004). The results from both model types show good agreement with the data indicating no influence of hysteresis at the oscillation period examined (T = 348 s). The models were then used to perform a parametric study to examine the relationship between oscillation period and hysteresis effects with periods ranging from 3 min to 180 min. At short oscillation periods, (T ≈ 180 s) the effects of hysteresis were negligible with both models providing similar results. As the oscillation period increased, the hysteretic model showed less amplitude damping than the non-hysteretic model. For periods greater than T = 60 min, the phase lag in the non-hysteretic model is greater than for the hysteretic one. For periods less than T = 60 min this trend is reversed and the hysteretic model produced a greater phase lag than the non-hysteretic model. These findings suggest that consideration of hysteresis dynamics in Richards' equation models has no influence on water table wave dispersion for short period forcing such as waves (T ≈ 10 s) whereas for long period forcing such as tides (T ≈ 12.25 h) or storm surges (T ≈ days) hysteresis dynamics should be taken into account.

  10. Hysteresis and the length dependence of calcium sensitivity in chemically skinned rat cardiac muscle.

    PubMed Central

    Harrison, S M; Lamont, C; Miller, D J

    1988-01-01

    1. The relationship between pCa (-log10[Ca2+]) and steady-state isometric tension has been investigated in saponin- or Triton-treated (chemically 'skinned') cardiac muscle of rat. 2. Hysteresis exists in the relationship such that the muscle is less sensitive to Ca2+ during increasing activation (as [Ca2+] is stepped upward) than during reducing activation (as [Ca2+] is stepped downward). 3. The extent of the hysteresis is insensitive to interventions that increase overall calcium sensitivity by chemical means, such as caffeine, carnosine or increased pH. 4. The extent of the hysteresis is sensitive to sarcomere length. The phenomenon is virtually absent above sarcomere lengths of about 2.2-2.3 microns but becomes progressively greater at shorter sarcomere lengths. 5. The effect of sarcomere length on calcium sensitivity is restricted to the upward-going (increasing activation) part of the pCa-tension loop below 2.2 microns. The downward-going (decreasing activation) part of the hysteretic relationship is virtually unaffected by sarcomere length up to 2.2 microns. 6. Significant alterations in sarcomere length do not occur during tension development in the experiments described here: the phenomenon is not attributable to experimental artifacts of this kind. 7. Hysteresis develops sufficiently rapidly to be consistent with a physiological relevance during the normal heart beat. 8. The effects of sarcomere length show that the phenomenon is not due to force per se since, for example, greater peak force produces less hysteresis as sarcomere length is increased towards 2.2 microns. 9. Tonicity increase (by high-molecular-weight dextran), which shrinks the myofilament lattice, increases calcium sensitivity but reduces the effect of sarcomere length on calcium sensitivity. 10. The results suggest that lattice shrinkage is the mechanism which accounts for hysteresis in, and the sarcomere length dependence of, calcium sensitivity in cardiac muscle. Images Fig. 1 Fig. 11 PMID:3171985

  11. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    SciTech Connect

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

    2015-09-25

    Hysteresis loops and Magnetic Barkhausen Noise in a single crystal α-iron containing a nonmagnetic particle were simulated based on the Laudau-Lifshitz-Gilbert equation. The analyses of domain morphologies and hysteresis loops show that reversal magnetization process is control by nucleation of reversed domains at nonmagnetic particle when the particle size reaches a particle value. In such a situation, the value of nucleation field is determined by the size of nonmagnetic particles, and moreover, coercive field and Magnetic Barkhausen Noise signal are strongly affected by the nucleation field of reversed domains.

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

    NASA Astrophysics Data System (ADS)

    de Ruiter, Rille; Semprebon, Ciro; van Gorcum, Mathijs; Duits, Michl 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.

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

    PubMed

    de Ruiter, Rille; Semprebon, Ciro; van Gorcum, Mathijs; Duits, Michl H G; Brinkmann, Martin; Mugele, Frieder

    2015-06-12

    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. PMID:26196804

  14. Magnetic hysteresis and magnetic flux patterns measured by acoustically stimulated electromagnetic response in a steel plate

    NASA Astrophysics Data System (ADS)

    Yamada, Hisato; Watanabe, Kakeru; Ikushima, Kenji

    2015-08-01

    Magnetic hysteresis loops are measured by ultrasonic techniques and used in visualizing the magnetic-flux distribution in a steel plate. The piezomagnetic coefficient determines the amplitude of acoustically stimulated electromagnetic (ASEM) fields, yielding the hysteresis behavior of the intensity of the ASEM response. By utilizing the high correspondence of the ASEM response to the magnetic-flux density, we image the specific spatial patterns of the flux density formed by an artificial defect in a steel plate specimen. Magnetic-flux probing by ultrasonic waves is thus shown to be a viable method of nondestructive material inspection.

  15. Dynamic hysteresis of tetragonal ferroelectrics: The resonance of 90-domain switching

    NASA Astrophysics Data System (ADS)

    Chen, D. P.; Liu, J.-M.

    2012-02-01

    The dynamic hysteresis of ferroelectric lattice with 90-domain structure in response to time-varying electric field of frequency ? and amplitude E0 is investigated using Monte Carlo simulation based on the Ginzburg-Landau phenomenological theory. A resonance mode of the polarization switching at low frequency range, associated with cluster dipole switching, beside the dipole switching resonance mode, is revealed, characterized by two separate peaks in the hysteresis area spectrum A(?). It is indicated that the power law scaling behaviors A(?) ?? for ? ? 0 and A(?) ?-? for ? ? ? remain applicable.

  16. Inverse compensation for hysteresis in piezoelectric actuator using an asymmetric rate-dependent model

    NASA Astrophysics Data System (ADS)

    Li, Wei; Chen, Xuedong; Li, Zilong

    2013-11-01

    This paper presents a modified Bouc-Wen model for asymmetric rate-dependent hysteresis in piezoelectric actuator. On this basis, we develop a new digital inverse controller with a simple structure cascaded in the feedforward path for piezoelectric actuator. In order to eliminate modeling errors and parameter uncertainties, the developed inverse controller is combined with a feedback loop to establish a hybrid control scheme. In our experiments, the proposed model together with the developed hybrid control scheme has shown significantly reduced tracking errors caused by asymmetric rate-dependent hysteresis in piezoelectric actuator.

  17. 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

  18. Steady state performance, photo-induced performance degradation and their relation to transient hysteresis in perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Jena, Ajay Kumar; Kulkarni, Ashish; Ikegami, Masashi; Miyasaka, Tsutomu

    2016-03-01

    Hysteresis in current-voltage curves of perovskite solar cells is a serious concern as it creates confusions about actual cell performance and raises questions on its reliability. Although a lot of effort has been made to understand the origin of hysteresis, knowing whether hysteresis affects the cell performance while they are in practical use (operated constantly at maximum power point) is not yet examined. In the present study, we investigate steady state performance and performance stability of perovskite solar cells (planar architecture with varying perovskite film thickness and TiO2 mesoscopic structure with different TiO2 compact layer thickness exhibiting hysteresis of different magnitudes) operating across an external load in relation to hysteresis. The planar cells with larger hysteresis exhibit a steady state current that closely matches the value determined on forward voltage scan. Cyclic photocurrent-dark current measurements on cells with hysteresis of different magnitudes reveal that photo-induced electrical instability (not material degradation), which might be originated from ion migration or photo-induced traps formation, is not related to hysteresis. Performance of the cells is recovered partially or fully, depending on the device structure, on storage in dark. TiO2 meso-structure cells tend to show complete recovery while the planar cells recover partially.

  19. 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,...

  20. ISO 16840-2:2007 load deflection and hysteresis measurements for a sample of wheelchair seating cushions.

    PubMed

    Hollington, James; Hillman, Susan J; Torres-Sánchez, Carmen; Boeckx, Jens; Crossan, Neil

    2014-04-01

    Load deflection and hysteresis measurements were made on 37 wheelchair seating cushions according to ISO 16840-2:2007. Load deflection plots for all 37 cushions are reported and fundamental aspects of graph interpretation discussed. ISO hysteresis data are also reported and interpretation discussed. PMID:24230981

  1. Contrasting diel hysteresis between soil autotrophic and heterotrophic respiration in a desert ecosystem under different rainfall scenarios.

    PubMed

    Song, Weimin; Chen, Shiping; Zhou, Yadan; Wu, Bo; Zhu, Yajuan; Lu, Qi; Lin, Guanghui

    2015-01-01

    Diel hysteresis occurs often between soil CO2 efflux (R(S)) and temperature, yet, little is known if diel hysteresis occurs in the two components of R(S), i.e., autotrophic respiration (R(A)) and heterotrophic respiration (R(H)), and how diel hysteresis will respond to future rainfall change. We conducted a field experiment in a desert ecosystem in northern China simulating five different scenarios of future rain regimes. Diel variations of soil CO2 efflux and soil temperature were measured on Day 6 and Day 16 following the rain addition treatments each month during the growing season. We found contrasting responses in the diel hysteresis of R(A) and R(H) to soil temperature, with a clockwise hysteresis loop for R(H) but a counter-clockwise hysteresis loop for R(A). Rain addition significantly increased the magnitude of diel hysteresis for both R(H) and R(A) on Day 6, but had no influence on either on Day 16 when soil moisture was much lower. These findings underline the different roles of biological (i.e. plant and microbial activities) and physical-chemical (e.g. heat transport and inorganic CO2 exchange) processes in regulating the diel hysteresis of R(A) and R(H), which should be considered when estimating soil CO2 efflux in desert regions under future rainfall regime. PMID:26615895

  2. Contrasting diel hysteresis between soil autotrophic and heterotrophic respiration in a desert ecosystem under different rainfall scenarios

    PubMed Central

    Song, Weimin; Chen, Shiping; Zhou, Yadan; Wu, Bo; Zhu, Yajuan; Lu, Qi; Lin, Guanghui

    2015-01-01

    Diel hysteresis occurs often between soil CO2 efflux (RS) and temperature, yet, little is known if diel hysteresis occurs in the two components of RS, i.e., autotrophic respiration (RA) and heterotrophic respiration (RH), and how diel hysteresis will respond to future rainfall change. We conducted a field experiment in a desert ecosystem in northern China simulating five different scenarios of future rain regimes. Diel variations of soil CO2 efflux and soil temperature were measured on Day 6 and Day 16 following the rain addition treatments each month during the growing season. We found contrasting responses in the diel hysteresis of RA and RH to soil temperature, with a clockwise hysteresis loop for RH but a counter-clockwise hysteresis loop for RA. Rain addition significantly increased the magnitude of diel hysteresis for both RH and RA on Day 6, but had no influence on either on Day 16 when soil moisture was much lower. These findings underline the different roles of biological (i.e. plant and microbial activities) and physical-chemical (e.g. heat transport and inorganic CO2 exchange) processes in regulating the diel hysteresis of RA and RH, which should be considered when estimating soil CO2 efflux in desert regions under future rainfall regime. PMID:26615895

  3. 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.

  4. Hysteresis of the Contact Angle around Spheres Adsorbed at Curved Fluid Interfaces

    NASA Astrophysics Data System (ADS)

    Senbil, Nesrin; He, Wei; Davidovitch, Benjamin; Dinsmore, Anthony

    2014-03-01

    When a particle adsorbs to a fluid interface, the geometry of the contact between the interface and the particle determines the force acting on the particle. We find a significant hysteresis in the contact angle, and -surprisingly- a strong dependence of the hysteresis on the shape of the interface. Hysteresis in the wetting of a fluid on a flat substrate is well known, whereby two contact angles are typically defined, corresponding to the advancing and receding cases. We find that the receding angle around the sphere changes with the shape of the interface. We use millimeter-sized glass spheres coated with PDMS and adsorbed at an air-water interface. High-resolution images are analyzed to obtain the contact geometry as the spheres are raised or lowered across the interface. We find advancing contact angles of approximately 107o and receding angles that range between 90o and 97o depending on the interface shape. Our results are important for understanding interactions between particles at interfaces and may shed new light on the origin of contact-angle hysteresis. This work is funded by the NSF through CBET-0967620 and by the Gulf of Mexico Research Initiative through the C-MEDS consortium.

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

    PubMed

    Aoi, Shinya; Katayama, Daiki; Fujiki, Soichiro; Tomita, Nozomi; Funato, Tetsuro; Yamashita, Tsuyoshi; Senda, Kei; Tsuchiya, Kazuo

    2013-04-01

    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

  6. A stability-based mechanism for hysteresis in the walktrot 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 walktrot 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 walktrot 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

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

    NASA Technical Reports Server (NTRS)

    Moore, Franklin K

    1956-01-01

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

  8. Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation

    NASA Technical Reports Server (NTRS)

    Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.

    2002-01-01

    The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.

  9. Discontinuity of mode transition and hysteresis in hydrogen inductively coupled plasma via a fluid model

    NASA Astrophysics Data System (ADS)

    Xu, Hui-Jing; Zhao, Shu-Xia; Fei, Gao; Yu-Ru, Zhang; Xue-Chun, Li; You-Nian, Wang

    2015-11-01

    A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to investigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determinative role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency. Project supported by the National Natural Science Foundation of China (Grant Nos.11175034, 11205025, 11305023, and 11075029).

  10. Untangling Perceptual Memory: Hysteresis and Adaptation Map into Separate Cortical Networks

    PubMed Central

    Schwiedrzik, Caspar M.; Ruff, Christian C.; Lazar, Andreea; Leitner, Frauke C.; Singer, Wolf; Melloni, Lucia

    2014-01-01

    Perception is an active inferential process in which prior knowledge is combined with sensory input, the result of which determines the contents of awareness. Accordingly, previous experience is known to help the brain “decide” what to perceive. However, a critical aspect that has not been addressed is that previous experience can exert 2 opposing effects on perception: An attractive effect, sensitizing the brain to perceive the same again (hysteresis), or a repulsive effect, making it more likely to perceive something else (adaptation). We used functional magnetic resonance imaging and modeling to elucidate how the brain entertains these 2 opposing processes, and what determines the direction of such experience-dependent perceptual effects. We found that although affecting our perception concurrently, hysteresis and adaptation map into distinct cortical networks: a widespread network of higher-order visual and fronto-parietal areas was involved in perceptual stabilization, while adaptation was confined to early visual areas. This areal and hierarchical segregation may explain how the brain maintains the balance between exploiting redundancies and staying sensitive to new information. We provide a Bayesian model that accounts for the coexistence of hysteresis and adaptation by separating their causes into 2 distinct terms: Hysteresis alters the prior, whereas adaptation changes the sensory evidence (the likelihood function). PMID:23236204

  11. Surface barrier and magnetic hysteresis of ac permeability in YBaCuO single crystal

    NASA Astrophysics Data System (ADS)

    Kugel, K. I.; Mamsurova, L. G.; Pigalskiy, K. S.; Rakhmanov, A. L.

    1998-05-01

    The nature of hysteretic behavior of the flux line lattice (FLL) contribution to ac magnetic permeability ( ?v) is analyzed for the case of YBa 2Cu 3O x single crystal (at applied magnetic field H? c axis). It is shown that hysteresis loops ?v( H) corresponding to different temperatures ( T=70-84 K) are scaled to a universal curve in normalized coordinates. Such a behavior is interpreted in terms of the FLL interaction with the crystal surface. The explicit relationship between ?v and magnetic induction B is found for the near-surface region of the superconductor. It is shown that the ?v( H) loops are closely related to the hysteresis of B at cycling of applied magnetic field. The latter hysteresis stems from the Bean-Livingston surface barrier. The estimates demonstrate strong suppression of the surface barrier in YBa 2Cu 3O x crystal in comparison to that expected for the ideal surface. As a result, the lower branch of the hysteresis loop corresponding to the increasing field is very close to the equilibrium ?v( H) curve and the surface barrier appreciably affects only the upper branch when magnetic flux leaves the sample. The comparison of theoretical predictions and experimental data provides an opportunity to refine the actual range of stability Hmax( B)- Hmin( B) for the FLL at fixed B for YBa 2Cu 3O x crystal in the case of H?c.

  12. Direct measurement of the thermal hysteresis of antifreeze proteins (AFPs) using sonocrystallization.

    PubMed

    Gaede-Koehler, Andrea; Kreider, Alexej; Canfield, Peter; Kleemeier, Malte; Grunwald, Ingo

    2012-12-01

    Antifreeze proteins (AFPs) are of great importance for applications in cryomedicine or the food industry. They are frequently used to lower the freezing point by preventing the growth of larger ice crystals; thus, it is paramount to determine their thermal hysteretic characteristics. However, the experimental analysis of the thermal hysteresis-an effect that is characteristic for AFPs-remains a challenging process. An easy-to-use test method for measuring the thermal hysteresis of AFPs was developed and tested with the type III AFPs. Traditional methods that have been used until now have their disadvantages and limitations. The new measurement method described in this paper allows detection of the complete cooling, freezing, heating, and melting process in a single measurement. This makes it possible to directly determine the thermal hysteresis as a functional effect of the antifreeze proteins. Measurements of the thermal hysteresis were performed by applying ultrasound to initiate the crystallization process of the antifreeze protein solution. This ultrasound technique also allows a crystallization process to be performed at defined temperature. The demonstrated results were highly reproducible and could be clearly read off the measurement curves. As a future perspective, this enables the design of automatic test devices that can be also miniaturized. PMID:23121544

  13. Temperature dependence of the hysteresis for the a-Si:H gate pH-ISFET

    NASA Astrophysics Data System (ADS)

    Chou, Jung Chuan; Tsai, Hsjian-Ming; Wang, Yii Fang

    2000-07-01

    In application of the pH-ISFET, the hysteresis and temperature effects are two important influences of accuracy. There have been many studies about the above subjects, however, the hysteresis behaviour will change with the temperature and affect the reproducibility of the devices. Hence, we study the temperature dependence of the hysteresis behaviour for the pH-ISFET with a-Si:H gate insulator deposited by the PE-LPCVD system in this paper. The thickness of the a-Si:H was about 2000 A. The temperature is controlled by the P.I.D. temperature controlled system and the hysteresis behaviour is measured by the constant voltage-constant current circuit and voltage-time recorder. The measurement is completed at 25 degree(s)C, 35 degree(s)C, 45 degree(s)C and 55 degree(s)C and the time after the pH changed is 4 min, The experimental results also compared with other materials of the gate insulator for pH-ISFET at the room temperature.

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

    SciTech Connect

    Li, Tao; Du, Gang; Zhang, Baoshun; Zeng, Zhongming

    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 (ΔV) 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〉, ΔV, 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. Contact angle hysteresis and phase separation in dry phospholipid films with cholesterol deposited on mica surface

    NASA Astrophysics Data System (ADS)

    Jurak, Ma?gorzata

    2015-02-01

    A series of apparent advancing and receding contact angles of water and diiodomethane was measured on the phospholipid/cholesterol monolayers physisorbed on the mica surfaces. It was found that the contact angles and their hystereses vary significantly depending on the lipid film composition and mutual miscibility of both components. These changes were much greater for water than diiodomethane. When the phase separation occurred, the hysteresis of water contact angle significantly decreased whereas the diiodomethane contact angle hysteresis increased considerably. Different behavior of both liquids may result from different mechanisms of the liquid droplets penetration/retention and points to structural changes that occur within the monolayers, including molecules rearrangement when exposed to water. The structure of the studied monolayer surfaces was confirmed by means of the microscopic techniques. The images are a visual evidence of cholesterol precipitation out the binary films at their specific stoichiometry. The results provide a new insight into the advancing/receding contact angles origin (and contact angle hysteresis) of polar and apolar liquids depending on the phospholipid/cholesterol monolayer composition, as well explanation of the origin of the contact angle hysteresis on the model biological surfaces, which are molecularly smooth.

  16. Special hysteresis effects in N{sub 2}-sorption and mercury-porosimetry measurements

    SciTech Connect

    Giesche, H.

    1996-12-31

    Model pore structures were prepared from dispersions of submicron monodispersed silica particles by a sedimentation process. Ordered dense sphere packing structures were observed with scanning electron microscopy. Nitrogen sorption- as well as Hg-porosimetry measurements confirmed the calculated values of the pore openings in those structures. In Hg-porosimetry measurements a two step extrusion curve was observed, when the pore system was only partially filled during the intrusion process. This two step curve was not observed in case the pore system was filled with mercury to more than 95% during the intrusion run. The mercury porosimetry results can be interpreted in terms of the coexistence of octahedral and tetrahedral voids (pores) in the examined sphere packing structure and their special arrangement within the structure (connectivity). Two models will be described to explain the general occurrence of hysteresis in Hg-porosimetry. The actual pore geometry is shown to have a profound influence on the hysteresis shape as well as a change in the contact angle (constant within each measurement) can result in totally different hysteresis curves. Nitrogen adsorption and desorption measurements on the same powders did not reveal any fine structure within the hysteresis range.

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

    NASA Astrophysics Data System (ADS)

    Li, Longbiao; Song, Yingdong

    2013-12-01

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

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

    PubMed Central

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

    2008-01-01

    When pulled along its axis, double-stranded DNA elongates abruptly at a force of ?65 pN. Two physical pictures have been developed to describe this overstretched state. The first proposes that strong forces induce a phase transition to a molten state consisting of unhybridized single strands. The second picture introduces an elongated hybridized phase called S-DNA. Little thermodynamic evidence exists to discriminate directly between these competing pictures. Here we show that within a microscopic model of DNA we can distinguish between the dynamics associated with each. In experiment, considerable hysteresis in a cycle of stretching and shortening develops as temperature is increased. Since there are few possible causes of hysteresis in a system whose extent is appreciable in only one dimension, such behavior offers a discriminating test of the two pictures of overstretching. Most experiments are performed upon nicked DNA, permitting the detachment (unpeeling) of strands. We show that the long-wavelength progression of the unpeeled front generates hysteresis, the character of which agrees with experiment only if we assume the existence of S-DNA. We also show that internal melting can generate hysteresis, the degree of which depends upon the nonextensive loop entropy of single-stranded DNA. PMID:17981894

  19. Hysteresis of tunnel current in w-GaN/AlGaN(0001) double-barrier structures

    SciTech Connect

    Razzhuvalov, A. N. Grinyaev, S. N.

    2008-05-15

    On the basis of a self-consistent solution of the Schroedinger and Poisson equations, the features of the tunnel-current hysteresis in w-GaN/AlGaN(0001) double-barrier structures are investigated. It is shown that the hysteresis loop depends on the mutual orientation of external and internal fields in the well and is wider at the voltage polarity when these fields compensate each other. Within the framework of the single-resonance approximation, a tunnel-current model in the double-barrier structure is developed, and the relation between the hysteresis-loop parameters and resonant states is found. It is established that the hysteresis loop can be relatively wide ({approx}4 V) even in geometrically symmetric structures with the participation of two resonances. In asymmetrical structures, the change in the growth-surface type results in enhancement or suppression of the hysteresis loop depending on the alternation of nonequivalent barriers.

  20. 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 CO2. 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.

  1. 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.

  2. Transient hysteresis of near-surface permafrost response to external forcing

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  3. Relationship Between Hysteresis Dissipated Energy and Temperature Rising in Fiber-Reinforced Ceramic-Matrix Composites Under Cyclic Loading

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-09-01

    In this paper, the relationship between hysteresis dissipated energy and temperature rising of the external surface in fiber-reinforced ceramic-matrix composites (CMCs) during the application of cyclic loading has been analyzed. The temperature rise, which is caused by frictional slip of fibers within the composite, is related to the hysteresis dissipated energy. Based on the fatigue hysteresis theories considering fibers failure, the hysteresis dissipated energy and a hysteresis dissipated energy-based damage parameter changing with the increase of cycle number have been investigated. The relationship between the hysteresis dissipated energy, a hysteresis dissipated energy-based damage parameter and a temperature rise-based damage parameter have been established. The experimental temperature rise-based damage parameter of unidirectional, cross-ply and 2D woven CMCs corresponding to different fatigue peak stresses and cycle numbers have been predicted. It was found that the temperature rise-based parameter can be used to monitor the fatigue damage evolution and predict the fatigue life of fiber-reinforced CMCs.

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

    NASA Astrophysics Data System (ADS)

    Oroumei, Azam; Tavanai, Hossein; Morshed, Mohammad

    2015-07-01

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

  5. Bifurcations and hysteresis of varying compliance vibrations in the primary parametric resonance for a ball bearing

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyong; Chen, Yushu; Cao, Qingjie

    2015-08-01

    This paper investigates the bifurcation and resonant hysteresis of varying compliance (VC) vibrations in a rigid-rotor ball bearing system with Hertzian contact and radial internal bearing clearance. With the aid of arc-length continuation, the harmonic balance and alternating frequency time (HB-AFT) technique is employed to trace the branches of periodic responses, for which the stability is also investigated using Floquet theory. It is found that the soft resonant hysteresis resulted from the Hertzian contact resonance dominates the primary parametric resonance. In addition, this paper also demonstrates that the mechanism of the period doubling in the case of small bearing clearances is arisen from one to two parametrical internal resonance in the primary resonant area, which can lead nonlinear responses such as quasi-period and chaotic motions to the system, and the evolvements of these complex behaviors are also explored.

  6. Inversion of hysteresis in quantum dot controlled quantum-wire transistor

    NASA Astrophysics Data System (ADS)

    Mller, C. R.; Worschech, L.; Forchel, A.

    2009-05-01

    In a quantum-wire transistor, pronounced floating-gate function of quantum dots is demonstrated with large threshold hysteresis exceeding 1.5 V. The charge state of the quantum dots is electrically controlled and, by applying a critical bias voltage along the quantum wire, the charging mechanism of the quantum dots is deactivated or, for bias voltages above this critical bias point, even inverted. It is shown that the charging as well as discharging of the quantum dots can be selectively switched off; i.e., the floating-gate function of the quantum dots is suppressed. The inversion of the hysteresis is explained within the framework of a capacitor model and the control of the charging mechanism is attributed to a dynamic gate efficiency of the quantum wire, which can be either larger or smaller than the quantum dot gate efficiency.

  7. Adaptive Fuzzy Hysteresis Band Current Controller for Four-Wire Shunt Active Filter

    NASA Astrophysics Data System (ADS)

    Hamoudi, F.; Chaghi, A.; Amimeur, H.; Merabet, E.

    2008-06-01

    This paper presents an adaptive fuzzy hysteresis band current controller for four-wire shunt active power filters to eliminate harmonics and to compensate reactive power in distribution systems in order to keep currents at the point of common coupling sinusoidal and in phase with the corresponding voltage and the cancel neutral current. The conventional hysteresis band known for its robustness and its advantage in current controlled applications is adapted with a fuzzy logic controller to change the bandwidth according to the operating point in order to keep the frequency modulation at tolerable limits. The algorithm used to identify the reference currents is based on the synchronous reference frame theory (dqγ). Finally, simulation results using Matlab/Simulink are given to validate the proposed control.

  8. Contact angle hysteresis of non-flattened-top micro/nanostructures.

    PubMed

    Moradi, Sona; Englezos, Peter; Hatzikiriakos, Savvas G

    2014-03-25

    A two-dimensional (2D) thermodynamic model is proposed to predict the contact angle (CA) and contact angle hysteresis (CAH) of different types of surface geometries, particularly those with asperities having nonflattened tops. The model is evaluated by micro/nano sinusoidal and parabolic patterns fabricated by laser ablation. These microstructures are analyzed thermodynamically through the use of the Gibbs free energy to obtain the equilibrium contact angle (CA) and contact angle hysteresis (CAH). The effects of the geometrical details of two types of microstructures on maximizing the superhydrophobicity of the nanopatterned surface are also discussed in an attempt to design surfaces with desired and/or optimum wetting characteristics. The analysis of the various surfaces reveals the important geometrical parameters that may lead to the lotus effect (high CA > 150 and low CAH < 10) or petal effect (high CA > 150 and high CAH ? 10). PMID:24588357

  9. Characterizing piezoscanner hysteresis and creep using optical levers and a reference nanopositioning stage

    SciTech Connect

    Xie, H.; Regnier, S.

    2009-04-15

    A method using atomic force microscope (AFM) optical levers and a reference nanopositioning stage has been developed to characterize piezoscanner hysteresis and creep. The piezoscanner is fixed on a closed-loop nanopositioning stage, both of which have the same arrangement on each axis of the three spatial directions inside the AFM-based nanomanipulation system. In order to achieve characterization, the optical lever is used as a displacement sensor to measure the relative movement between the nanopositioning stage and the piezoscanner by lateral tracking a well-defined slope with the tapping mode of the AFM cantilever. This setup can be used to estimate a piezoscanner's voltage input with a reference displacement from the nanopositioning stage. The hysteresis and creep were accurately calibrated by the method presented, which use the current setup of the AFM-based nanomanipulation system without any modification or additional devices.

  10. Damping measurements of laminated composite materials and aluminum using the hysteresis loop method

    NASA Astrophysics Data System (ADS)

    Abramovich, H.; Govich, D.; Grunwald, A.

    2015-10-01

    The damping characteristics of composite laminates made of Hexply 8552 AGP 280-5H (fabric), used for structural elements in aeronautical vehicles, have been investigated in depth using the hysteresis loop method and compared to the results for aluminum specimens (2024 T351). It was found that the loss factor, η, obtained by the hysteresis loop method is linearly dependent only on the applied excitation frequency and is independent of the preloading and the stress amplitudes. For the test specimens used in the present tests series, it was found that the damping of the aluminum specimens is higher than the composite ones for longitudinal direction damping, while for bending vibrations the laminates exhibited higher damping values.

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

    PubMed Central

    Zhang, Yang; Faraone, Antonio; Kamitakahara, William A.; Liu, Kao-Hsiang; Mou, Chung-Yuan; Leo, Juscelino B.; Chang, Sung; Chen, Sow-Hsin

    2011-01-01

    A neutron scattering technique was developed to measure the density of heavy water confined in a nanoporous silica matrix in a temperature-pressure range, from 300 to 130K and from 1 to 2,900bars, where bulk water will crystalize. We observed a prominent hysteresis phenomenon in the measured density profiles between warming and cooling scans above 1,000bars. We interpret this hysteresis phenomenon as support (although not a proof) of the hypothetical existence of a first-order liquidliquid phase transition of water that would exist in the macroscopic system if crystallization could be avoided in the relevant phase region. Moreover, the density data we obtained for the confined heavy water under these conditions are valuable to large communities in biology and earth and planetary sciences interested in phenomena in which nanometer-sized water layers are involved. PMID:21746898

  12. A Neural-FEM tool for the 2-D magnetic hysteresis modeling

    NASA Astrophysics Data System (ADS)

    Cardelli, E.; Faba, A.; Laudani, A.; Lozito, G. M.; Riganti Fulginei, F.; Salvini, A.

    2016-04-01

    The aim of this work is to present a new tool for the analysis of magnetic field problems considering 2-D magnetic hysteresis. In particular, this tool makes use of the Finite Element Method to solve the magnetic field problem in real device, and fruitfully exploits a neural network (NN) for the modeling of 2-D magnetic hysteresis of materials. The NS has as input the magnetic inductions components B at the k-th simulation step and returns as output the corresponding values of the magnetic field H corresponding to the input pattern. It is trained by vector measurements performed on the magnetic material to be modeled. This input/output scheme is directly implemented in a FEM code employing the magnetic potential vector A formulation. Validations through measurements on a real device have been performed.

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

    NASA Astrophysics Data System (ADS)

    Hoffmann, Geoffrey W.; Benson, Maurice W.

    1986-08-01

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

  14. Neural Controller Design-Based Adaptive Control for Nonlinear MIMO Systems With Unknown Hysteresis Inputs.

    PubMed

    Liu, Yan-Jun; Tong, Shaocheng; Chen, C L Philip; Li, Dong-Juan

    2016-01-01

    This paper studies an adaptive neural control for nonlinear multiple-input multiple-output systems in interconnected form. The studied systems are composed of N subsystems in pure feedback structure and the interconnection terms are contained in every equation of each subsystem. Moreover, the studied systems consider the effects of Prandtl-Ishlinskii (PI) hysteresis model. It is for the first time to study the control problem for such a class of systems. In addition, the proposed scheme removes an important assumption imposed on the previous works that the bounds of the parameters in PI hysteresis are known. The radial basis functions neural networks are employed to approximate unknown functions. The adaptation laws and the controllers are designed by employing the backstepping technique. The closed-loop system can be proven to be stable by using Lyapunov theorem. A simulation example is studied to validate the effectiveness of the scheme. PMID:25898325

  15. Simulation of hysteresis curves of crystalline ferroelectrics using the controlling electric field parameters

    NASA Astrophysics Data System (ADS)

    Zakharov, A. Yu.; Bichurin, M. I.

    2015-12-01

    We propose a description of switching in crystalline ferroelectrics taking into account the action of a varying external electric field, based on the equations of relaxation processes. We suppose that the probability of switching of domains depends not only on the instantaneous value of the controlling field, but also on the rate of its variation. The time dependence of the controlling field is defined by an arbitrary periodic function. The equations of the domain switching processes in a ferroelectric are derived and the exact analytic solutions to these equations are obtained. Numerical analysis of the interrelation between the frequency of the sinusoidal external field and the shape of the hysteresis curves is carried out on the basis of the resultant solutions. It is shown that the inclusion of the dependence of relaxation time on the rate of the controlling field variation makes it possible to sufficiently improve the agreement between the results of simulation of the ferroelectric hysteresis curves and the experimental data.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  17. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor.

    PubMed

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio; Markos, Christos; Bang, Ole

    2016-01-25

    The effect of humidity on annealing of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs) and the resulting humidity responsivity are investigated. Typically annealing of PMMA POFs is done in an oven without humidity control around 80C and therefore at low humidity. We demonstrate that annealing at high humidity and high temperature improves the performances of mPOFBGs in terms of stability and sensitivity to humidity. PMMA POFBGs that are not annealed or annealed at low humidity level will have a low and highly temperature dependent sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more than 230 nm without loss in the grating strength. PMID:26832503

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

    NASA Astrophysics Data System (ADS)

    Ekkachai, Kittipong; Tungpimolrut, Kanokvate; Nilkhamhang, Itthisek

    2013-11-01

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

  19. Disorder-driven first-order phase transformations: A model for hysteresis

    SciTech Connect

    Dahmen, K.; Kartha, S.; Krumhansl, J.A.; Roberts, B.W.; Sethna, J.P.; Shore, J.D. )

    1994-05-15

    Hysteresis loops in some magnetic systems are composed of small avalanches (manifesting themselves as Barkhausen pulses). Hysteresis loops in other first-order phase transitions (including some magnetic systems) often occur via one large avalanche. The transition between these two limiting cases is studied, by varying the disorder in the zero-temperature random-field Ising model. Sweeping the external field through zero at weak disorder, we get one large avalanche with small precursors and aftershocks. At strong disorder, we get a distribution of small avalanches (small Barkhausen effect). At the critical value of disorder where a macroscopic jump in the magnetization first occurs, universal power-law behavior of the magnetization and of the distribution of (Barkhausen) avalanches is found. This transition is studied by mean-field theory, perturbative expansions, and numerical simulation in three dimensions.

  20. Hydride formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape

    NASA Astrophysics Data System (ADS)

    Syrenova, Svetlana; Wadell, Carl; Nugroho, Ferry A. A.; Gschneidtner, Tina A.; Diaz Fernandez, Yuri A.; Nalin, Giammarco; Świtlik, Dominika; Westerlund, Fredrik; Antosiewicz, Tomasz J.; Zhdanov, Vladimir P.; Moth-Poulsen, Kasper; Langhammer, Christoph

    2015-12-01

    Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of hydride formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during hydride formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that hydride decomposition either occurs incoherently or via different kinetic pathways.

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

    NASA Astrophysics Data System (ADS)

    Mansanarez, Valentin; Le Coz, Jrme; Renard, Benjamin; Lang, Michel; Birgand, Franois

    2015-04-01

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

  2. Estimate Interface Shear Stress of Unidirectional C/SiC Ceramic Matrix Composites from Hysteresis Loops

    NASA Astrophysics Data System (ADS)

    Longbiao, Li; Yingdong, Song; Youchao, Sun

    2013-08-01

    The tensile-tensile fatigue behavior of unidirectional C/SiC ceramic matrix composites at room and elevated temperature has been investigated. An approach to estimate the interface shear stress of ceramic matrix composites under fatigue loading has been developed. Based on the damage mechanisms of fiber sliding relative to matrix in the interface debonded region upon unloading and subsequent reloading, the unloading interface reverse slip length and reloading interface new slip length are determined by the fracture mechanics approach. The hysteresis loss energy for the strain energy lost per volume during corresponding cycle is formulatd in terms of interface shear stress. By comparing the experimental hysteresis loss energy with the computational values, the interface shear stress of unidirectional C/SiC ceramic composites corresponding to different cycles at room and elevated temperatures has been predicted.

  3. Hysteresis compensation of photoluminescence in ZnS:Cu for noncontact shaft torque sensing.

    PubMed

    Cho, Min-Young; Kim, Ji-Sik; Kim, Gi-Woo

    2016-03-01

    This paper presents a preliminary investigation of loading rate-dependent hysteresis of photoluminescence (PL) by phosphorescence quenching of copper-doped zinc sulfide (ZnS:Cu) microparticles in response to dynamic torsional loading. Precision sinusoidal torque waveforms in the frequency range of 0.5-3 Hz are used to identify the loading rate-dependent (i.e., frequency-dependent) nonlinear hysteresis phenomenon. The potential of the application of PL is demonstrated by successfully measuring the sinusoidal torque applied to a rotational shaft by evaluating the loading rate-dependent PL intensity signature using a photomultiplier tube. In addition, the potential of noncontact shaft torque sensing is demonstrated successfully by the simple compensation derived from ad hoc heuristic characterization. PMID:26974628

  4. Reduction of hysteresis for carbon nanotube mobility measurements using pulsed characterization.

    PubMed

    Estrada, David; Dutta, Sumit; Liao, Albert; Pop, Eric

    2010-02-26

    We describe a pulsed measurement technique for suppressing hysteresis for carbon nanotube (CNT) device measurements in air, vacuum, and over a wide temperature range (80-453 K). Varying the gate pulse width and duty cycle probes the relaxation times associated with charge trapping near the CNT, found to be up to the 0.1-10 s range. Longer off times between voltage pulses enable consistent, hysteresis-free measurements of CNT mobility. A tunneling front model for charge trapping and relaxation is also described, suggesting trap depths up to 4-8 nm for CNTs on SiO2. Pulsed measurements will also be applicable for other nanoscale devices such as graphene, nanowires, or molecular electronics, and could enable probing trap relaxation times in a variety of material system interfaces. PMID:20097980

  5. Studies of hysteresis in two-dimensional kinetic Ising model using the FORC technique

    NASA Astrophysics Data System (ADS)

    Robb, Daniel; Novotny, Mark; Rikvold, Per Arne

    2004-03-01

    We describe the FORC (first order reversal curve) technique [1] for hysteresis, first developed as an experimental method to better characterize magnetic materials, and present FORC distributions for simulations of a square-lattice kinetic Ising model. To understand the simulation results, we apply a theory of magnetization reversal for the multidroplet (MD) regime [2] for homogeneous nucleation and growth, also called the Kolmogorov-Johnson-Mehl-Avrami regime. The FORC `partial hysteresis' loops exhibit different properties than those of systems with strong disorder [1]. We compare the simulation and the theory for several lattice sizes, frequencies of the external field, and temperatures. [1] C.R. Pike, A.P. Roberts, and K.L. Verosub, J. Appl. Phys. 85, 6660 (1999). [2] S.W. Sides, P.A. Rikvold, and M.A. Novotny, Phys. Rev. E 59, 2710 (1999).

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

    SciTech Connect

    Zhang, Yang; Faraone, Antonio; Kamitakahara, William; Liu, Kao-Hsiang; Mou, Chung-Yuan; Leao, Juscelino B; Chang, Sung C; Chen, Sow-hsin H

    2011-01-01

    A neutron scattering technique was developed to measure the density of heavy water confined in a nanoporous silica matrix in a temperature-pressure range, from 300 to 130 K and from 1 to 2,900 bars, where bulk water will crystalize. We observed a prominent hysteresis phenomenon in the measured density profiles between warming and cooling scans above 1,000 bars. We inter- pret this hysteresis phenomenon as support (although not a proof) of the hypothetical existence of a first-order liquid liquid phase transition of water that would exist in the macroscopic system if crystallization could be avoided in the relevant phase region. Moreover, the density data we obtained for the confined heavy water under these conditions are valuable to large communities in biology and earth and planetary sciences interested in phenomena in which nanometer-sized water layers are involved.

  7. Precision control of piezo-actuated optical deflector with nonlinearity correction based on hysteresis model

    NASA Astrophysics Data System (ADS)

    Wang, Geng; Guan, Chunlin; Zhang, Xiaojun; Zhou, Hong; Rao, Changhui

    2014-04-01

    The hysteresis nonlinearity of piezoelectric actuator is one of the main defects in the control of optical deflector which is widely used as a key component in adaptive optics system. In this paper, a control method combining the feedforward and feedback controllers is proposed to precisely control the deflection angle of an optical deflector. The inverse of an asymmetric Prandtl-Ishlinskii (PI) hysteresis model is utilized in the feedforward loop, and a PID controller is used in the feedback loop. Then, a tracking control experiment for the desired triangle wave was performed. From the experimental results, we can see that the response of the optical deflector is linearized and the positioning precision of optical deflector is significantly improved.

  8. Precision beam pointing control with jitter attenuation by optical deflector exhibiting dynamic hysteresis in COIL

    NASA Astrophysics Data System (ADS)

    Ma, Yan-Hua; Zhang, Zeng-Bao; Zhang, Zhi-Guo; Liu, Qin; He, Xin; Shi, Wen-Bo; Mao, Jian-Qin; Jin, Yu-Qi

    2015-02-01

    Due to the existence of various disturbances during the lasing process of the chemical oxygen iodine laser (COIL), the optical beam pointing performance is severely degraded. In this paper, an adaptive control methodology is proposed for the precise pointing control of the optical beam with active beam jitter rejection using a giant magnetostrictive optical deflector (GMOD) which exhibits severe dynamic hysteresis nonlinearity. In particular, a least square support vector machine (LS-SVM) based fast compensator is employed to eliminate the dynamic hysteresis without the inverse model construction. Then an improved feedforward adaptive filter is developed to deal with jitter attenuation when the full-coherent reference signal is unavailable. To improve the stability and overall robustness of the controller, especially when a large initial bias exists, a PI controller is placed in parallel with the adaptive filter. Experimental results validate the precise pointing ability of the proposed control method.

  9. 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.

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

    PubMed

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

    2013-10-01

    Lattice Boltzmann method (LBM) is an effective tool for simulating the contact-line motion due to the nature of its microscopic dynamics. In contact-line motion, contact-angle hysteresis is an inherent phenomenon, but it is neglected in most existing color-gradient based LBMs. In this paper, a color-gradient based multiphase LBM is developed to simulate the contact-line motion, particularly with the hysteresis of contact angle involved. In this model, the perturbation operator based on the continuum surface force concept is introduced to model the interfacial tension, and the recoloring operator proposed by Latva-Kokko and Rothman is used to produce phase segregation and resolve the lattice pinning problem. At the solid surface, the color-conserving wetting boundary condition [Hollis et al., IMA J. Appl. Math. 76, 726 (2011)] is applied to improve the accuracy of simulations and suppress spurious currents at the contact line. In particular, we present a numerical algorithm to allow for the effect of the contact-angle hysteresis, in which an iterative procedure is used to determine the dynamic contact angle. Numerical simulations are conducted to verify the developed model, including the droplet partial wetting process and droplet dynamical behavior in a simple shear flow. The obtained results are compared with theoretical solutions and experimental data, indicating that the model is able to predict the equilibrium droplet shape as well as the dynamic process of partial wetting and thus permits accurate prediction of contact-line motion with the consideration of contact-angle hysteresis. PMID:24229303

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  12. QT-RR hysteresis is caused by differential autonomic states during exercise and recovery

    PubMed Central

    Pelchovitz, Daniel J.; Ng, Jason; Chicos, Alexandru B.; Bergner, Daniel W.

    2012-01-01

    QT-RR hysteresis is characterized by longer QT intervals at a given RR interval while heart rates are increasing during exercise and shorter QT intervals at the same RR interval while heart rates are decreasing during recovery. It has been attributed to a lagging QT response to different directional changes in RR interval during exercise and recovery. Twenty control subjects (8 males, age 51 6 yr), 16 subjects with type 2 diabetes (12 males, age 56 8 yr), 71 subjects with coronary artery disease (CAD) and preserved left ventricular ejection fraction (LVEF) (?50%) (51 males, age 59 12 yr), and 17 CAD subjects with depressed LVEF (<50%) (13 males, age 57 10 yr) underwent two 16-min exercise tests followed by recovery. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise. QT-RR hysteresis was quantified as: 1) the area bounded by the QT-RR relationships for exercise and recovery in the range of the minimum RR interval at peak exercise to the minimum RR interval + 100 ms and 2) the difference in QT interval duration between exercise and recovery at the minimum RR interval achieved during peak exercise plus 50 ms (?QT). The effect of parasympathetic blockade was assessed by substituting the QT-RR relationship after parasympathetic blockade. QT-RR hysteresis was positive in all groups at baseline and reversed by parasympathetic blockade (P < 0.01). We conclude that QT-RR hysteresis is not caused by different directional changes in RR interval during exercise and recovery. Instead, it is predominantly mediated by differential autonomic nervous system effects as the heart rate increases during exercise vs. as it decreases during recovery. PMID:22542617

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

    NASA Astrophysics Data System (ADS)

    Grasso, F.; Paoli, R.

    2000-12-01

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

  14. Simulation of thermomechanical and electrothermal hysteresis phenomena in porous nickel titanium

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I. V.

    2014-02-01

    There is represented a general scheme of functioning and the corresponding model of a porous biomicrofluid matrix based on nickel titanium, which possesses a shape-memory effect, prepared by the method of selective laser sintering. The simulation of thermomechanical and electrothermal hysteresis phenomena composes the basis of the functioning of this MEMS. Such a model can be used for estimating the efficiency and controllability of drug delivery systems via the change in the volume of pores.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    PubMed

    Melle, Sonia; Caldern, Oscar G; Egatz-Gmez, Ana; Cabrera-Granado, E; Carreo, F; Antn, M A

    2015-11-01

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

  17. Hysteresis of a current-voltage characteristic of a superconducting film in a magnetic field

    NASA Astrophysics Data System (ADS)

    Bezuglyj, A. I.

    1999-10-01

    Current-voltage characteristics (CVCs) of a wide superconducting film are considered for various magnetic fields. Near Tc heating of normal excitations leads to essential nonlinearity of the CVC in the flux-flow regime. At magnetic fields B lower than the characteristic field BH, the current-biased CVC has two instability points responsible for its hysteresis, whereas at B> BH the CVC is non-hysteretic.

  18. Iodine Migration and its Effect on Hysteresis in Perovskite Solar Cells.

    PubMed

    Li, Cheng; Tscheuschner, Steffen; Paulus, Fabian; Hopkinson, Paul E; Kießling, Johannes; Köhler, Anna; Vaynzof, Yana; Huettner, Sven

    2016-03-01

    The migration and accumulation of iodide ions create a modulation of the respective interfacial barriers causing the hysteresis in solar cells based on methylammonium lead iodide perovskites. Iodide ions are identified as the migrating species by measuring temperature dependent current-transients and photoelectron spectroscopy. The involved changes in the built-in potential due to ion migration are directly measured by electroabsorption spectroscopy. PMID:26823239

  19. Hysteresis and metastability of Bose-Einstein-condensed clouds of atoms confined in ring potentials

    NASA Astrophysics Data System (ADS)

    Roussou, A.; Tsibidis, G. D.; Smyrnakis, J.; Magiropoulos, M.; Efremidis, Nikolaos K.; Jackson, A. D.; Kavoulakis, G. M.

    2015-02-01

    We consider a Bose-Einstein-condensed cloud of atoms which rotate in a toroidal or annular potential. Assuming one-dimensional motion, we evaluate the critical frequencies associated with the effect of hysteresis and the critical coupling for stability of the persistent currents. We perform these calculations using both the mean-field approximation and the method of numerical diagonalization of the many-body Hamiltonian which includes corrections due to the finiteness of the atom number.

  20. Investigation of the hysteresis phenomena in steady shock reflection using kinetic and continuum methods

    NASA Astrophysics Data System (ADS)

    Ivanov, M.; Zeitoun, D.; Vuillon, J.; Gimelshein, S.; Markelov, G.

    1996-05-01

    The problem of transition of planar shock waves over straight wedges in steady flows from regular to Mach reflection and back was numerically studied by the DSMC method for solving the Boltzmann equation and finite difference method with FCT algorithm for solving the Euler equations. It is shown that the transition from regular to Mach reflection takes place in accordance with detachment criterion while the opposite transition occurs at smaller angles. The hysteresis effect was observed at increasing and decreasing shock wave angle.

  1. Dynamic characterization of hysteresis elements in mechanical systems. I. Theoretical analysis.

    PubMed

    Al-Bender, F; Symens, W

    2005-03-01

    The pre-sliding-pre-rolling phase of friction behavior is dominated by rate-independent hysteresis. Many machine elements in common engineering use exhibit, therefore, the characteristic of "hysteresis springs," for small displacements at least. Plain and rolling element bearings that are widely used in motion guidance of machine tools are typical examples. While the presence of a hysteresis element may mark the character of the resulting dynamics, little is to be found about this topic in the literature. The study of the nonlinear dynamics caused by such elements becomes imperative if we wish to achieve accurate control of such machines. In this Part I of the investigation, we examine a single-degree-of-freedom mass-hysteresis-spring system and show that, while the free response case is amenable to an exact solution, the more important case of forced response has no closed form solution and requires other methods of treatment. We consider harmonic-balance analysis methods (which are common analysis tools in engineering) suitable for frequency-domain treatment, in particular the approximate describing function (DF) method, and compare those results with "exact" numerical simulations. The DF method yields basically a linear equation with amplitude-dependent modal parameters. We find that agreement in the frequency response function, between DF and exact solution, is good for small excitation amplitudes and for very large amplitudes. Intermediate values, however, show high sensitivity to amplitude variations and, consequently, no regular solution is obtainable by either approach. This appears to be an inherent property of the system pointing to the need for developing further analysis methods. Experimental verification of the analysis outlined in this Part I is given in Part II of the paper. PMID:15836259

  2. Wetting hysteresis induced by temperature changes: Supercooled water on hydrophobic surfaces.

    PubMed

    Heydari, Golrokh; Sedighi Moghaddam, Maziar; Tuominen, Mikko; Fielden, Matthew; Haapanen, Janne; Mäkelä, Jyrki M; Claesson, Per M

    2016-04-15

    The state and stability of supercooled water on (super)hydrophobic surfaces is crucial for low temperature applications and it will affect anti-icing and de-icing properties. Surface characteristics such as topography and chemistry are expected to affect wetting hysteresis during temperature cycling experiments, and also the freezing delay of supercooled water. We utilized stochastically rough wood surfaces that were further modified to render them hydrophobic or superhydrophobic. Liquid flame spraying (LFS) was utilized to create a multi-scale roughness by depositing titanium dioxide nanoparticles. The coating was subsequently made non-polar by applying a thin plasma polymer layer. As flat reference samples modified silica surfaces with similar chemistries were utilized. With these substrates we test the hypothesis that superhydrophobic surfaces also should retard ice formation. Wetting hysteresis was evaluated using contact angle measurements during a freeze-thaw cycle from room temperature to freezing occurrence at -7°C, and then back to room temperature. Further, the delay in freezing of supercooled water droplets was studied at temperatures of -4°C and -7°C. The hysteresis in contact angle observed during a cooling-heating cycle is found to be small on flat hydrophobic surfaces. However, significant changes in contact angles during a cooling-heating cycle are observed on the rough surfaces, with a higher contact angle observed on cooling compared to during the subsequent heating. Condensation and subsequent frost formation at sub-zero temperatures induce the hysteresis. The freezing delay data show that the flat surface is more efficient in enhancing the freezing delay than the rougher surfaces, which can be rationalized considering heterogeneous nucleation theory. Thus, our data suggests that molecular flat surfaces, rather than rough superhydrophobic surfaces, are beneficial for retarding ice formation under conditions that allow condensation and frost formation to occur. PMID:26821148

  3. Genetic algorithm identification of a H-moving vector hysteresis model

    NASA Astrophysics Data System (ADS)

    Cardelli, E.; Faba, A.

    2014-02-01

    In this work we present an identification procedure for a vector hysteresis model defined by a H-moving approach. The model parameters are identified by means of a suitable implementation of a genetic algorithm with a set of experimental data. The analytical formulation of the model and the characteristics of the genetic algorithm used are described. A comparison between computed data and experimental measurements for a not oriented grain Si-Fe magnetic steel with a weak lamination anisotropy are reported.

  4. Modeling of Rate-Dependent Hysteresis Using a GPO-Based Adaptive Filter

    PubMed Central

    Zhang, Zhen; Ma, Yaopeng

    2016-01-01

    A novel generalized play operator-based (GPO-based) nonlinear adaptive filter is proposed to model rate-dependent hysteresis nonlinearity for smart actuators. In the proposed filter, the input signal vector consists of the output of a tapped delay line. GPOs with various thresholds are used to construct a nonlinear network and connected with the input signals. The output signal of the filter is composed of a linear combination of signals from the output of GPOs. The least-mean-square (LMS) algorithm is used to adjust the weights of the nonlinear filter. The modeling results of four adaptive filter methods are compared: GPO-based adaptive filter, Volterra filter, backlash filter and linear adaptive filter. Moreover, a phenomenological operator-based model, the rate-dependent generalized Prandtl-Ishlinskii (RDGPI) model, is compared to the proposed adaptive filter. The various rate-dependent modeling methods are applied to model the rate-dependent hysteresis of a giant magnetostrictive actuator (GMA). It is shown from the modeling results that the GPO-based adaptive filter can describe the rate-dependent hysteresis nonlinear of the GMA more accurately and effectively. PMID:26861349

  5. Thin three-dimensional droplets on an oscillating substrate with contact angle hysteresis.

    PubMed

    Bradshaw, J; Billingham, J

    2016-01-01

    Recent experiments [P. Brunet, J. Eggers, and R. D. Deegan, Phys. Rev. Lett. 99, 144501 (2007)10.1103/PhysRevLett.99.144501] have shown that a liquid droplet on an inclined plane can be made to move uphill by sufficiently strong, vertical oscillations. In order to investigate this counterintuitive phenomenon we use a model in which liquid inertia and viscosity are assumed negligible so that the motion of the droplet is dominated by the applied acceleration due to the oscillation of the plate, gravity, and surface tension. We explain how the leading order motion of the droplet can be separated into a spreading mode and a swaying mode. For a linear contact line law, the maximum rise velocity occurs when these modes are in phase. We show that, both with and without contact angle hysteresis, the droplet can climb uphill and also that, for certain contact line laws, the motion of the droplet can produce footprints similar to experimental results. We show that if the two modes are out of phase when there is no contact angle hysteresis, the inclusion of hysteresis can force them into phase. This in turn increases the rise velocity of the droplet and can, in some cases, cause a sliding droplet to climb. PMID:26871170

  6. Anomalous contact angle hysteresis of a captive bubble: advancing contact line pinning.

    PubMed

    Hong, Siang-Jie; Chang, Feng-Ming; Chou, Tung-He; Chan, Seong Heng; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2011-06-01

    Contact angle hysteresis of a sessile drop on a substrate consists of continuous invasion of liquid phase with the advancing angle (θ(a)) and contact line pinning of liquid phase retreat until the receding angle (θ(r)) is reached. Receding pinning is generally attributed to localized defects that are more wettable than the rest of the surface. However, the defect model cannot explain advancing pinning of liquid phase invasion driven by a deflating bubble and continuous retreat of liquid phase driven by the inflating bubble. A simple thermodynamic model based on adhesion hysteresis is proposed to explain anomalous contact angle hysteresis of a captive bubble quantitatively. The adhesion model involves two solid–liquid interfacial tensions (γ(sl) > γ(sl)′). Young’s equation with γ(sl) gives the advancing angle θ(a) while that with γ(sl)′ due to surface rearrangement yields the receding angle θ(r). Our analytical analysis indicates that contact line pinning represents frustration in surface free energy, and the equilibrium shape corresponds to a nondifferential minimum instead of a local minimum. On the basis of our thermodynamic model, Surface Evolver simulations are performed to reproduce both advancing and receding behavior associated with a captive bubble on the acrylic glass. PMID:21545100

  7. Droplet hysteresis investigation on non-wetting striped textured surfaces: A lattice Boltzmann study

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The Cassie-Baxter model is widely used to predict the apparent contact angles on textured super-hydrophobic surfaces. However, it has been challenged by some recent studies, since it does not consider contact angle hysteresis and surface structure characteristics near the contact line. The present study is to investigate the contact angle hysteresis on striped textured surfaces, and its elimination through vibrating the substrate. The two-phase flow is simulated by a recently proposed lattice Boltzmann model for high-density-ratio flows. Droplet evolutions under various initial contact angles are simulated, and it is found that different contact angles exist for the same textured surface. The importance of the contact line structure for droplet pinning is underlined via a study of droplet behavior on a composite substrate, with striped textured structure inside and flat structure outside. A stick-jump motion is found for the advancing contact line on the striped textured surface. Due to hysteresis, the contact angles after advancing are not consistent with the Cassie-Baxter model. The stable equilibrium is obtained through properly vibrating the substrate, and the resulted contact angles are consistent with Cassie's predictions.

  8. 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

  9. Magnetic hysteresis and Barkhausen noise emission analysis of magnetic materials and composites

    NASA Astrophysics Data System (ADS)

    Prabhu Gaunkar, Neelam

    specialchapt{ABSTRACT}. Barkhausen emission studies have been used to analyze the effect of residual stresses in ferromagnetic materials. The stresses generated due to mechanical wear and tear, abrasion and prolonged use can also lead to phase changes within the material. These phase changes can cause damage to the structural parts and should be prevented. In this study we analyze the magnetic hysteresis and Barkhausen noise profile of materials with more than one ferromagnetic phase. The correlation between the hysteresis and Barkhausen noise profiles for such materials is studied. Secondary Barkhausen emission peaks can be simulated for such materials. Experimental observations are compared with simulation measurements. Drawing a correlation between the secondary emergent peaks and the composition of each secondary phase should lead to an improved technique for non-destructive characterization of ferromagnetic materials. . Improved sensor-to-specimen coupling is also essential for conducting Barkhausen noise measurements of multiphase materials which may also have different surface geometries. A finite element study was conducted to optimize the design parameters of the magnetizing core in a Barkhausen noise sensor. Several sensor parameters inclusive of core material, core-tip curvature, core length and pole spacing were studied. A procedure for developing a high sensitivity Barkhausen noise sensor by design optimization based on finite element simulations has been demonstrated. The study also shows the applicability of Barkhausen emission and magnetic hysteresis analysis as advanced tools of non-destructive characterization of ferromagnetic materials.

  10. Emergence of Hysteresis and Transient Ferroelectric Response in Organo-Lead Halide Perovskite Solar Cells.

    PubMed

    Chen, Hsin-Wei; Sakai, Nobuya; Ikegami, Masashi; Miyasaka, Tsutomu

    2015-01-01

    Although there has been rapid progress in the efficiency of perovskite-based solar cells, hysteresis in the current-voltage performance is not yet completely understood. Owing to its complex structure, it is not easy to attribute the hysteretic behavior to any one of different components, such as the bulk of the perovskite or different heterojunction interfaces. Among organo-lead halide perovskites, methylammonium lead iodide perovskite (CH3NH3PbI3) is known to have a ferroelectric property. The present investigation reveals a strong correlation between transient ferroelectric polarization of CH3NH3PbI3 induced by an external bias in the dark and hysteresis enhancement in photovoltaic characteristics. Our results demonstrate that the reverse bias poling (-0.3 to -1.1 V) of CH3NH3PbI3 photovoltaic layers prior to the photocurrent-voltage measurement generates stronger hysteresis whose extent changes significantly by the cell architecture. The phenomenon is interpreted as the effect of remanent polarization in the perovskite film on the photocurrent, which is most enhanced in planar perovskite structures without mesoporous scaffolds. PMID:26263106

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

    PubMed

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2015-01-01

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

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

    PubMed

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

    2014-06-01

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

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

    PubMed

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

    2007-06-01

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

  14. a Thermal Conduction Switch Based on Low Hysteresis Nitife Shape Memory Alloy Helical Springs

    NASA Astrophysics Data System (ADS)

    Krishnan, V. B.; Bewerse, C.; Notardonato, W. U.; Vaidyanathan, R.

    2008-03-01

    Shape memory alloy (SMA) actuators possess an inherent property of sensing a change in temperature and delivering significant force against external loads through a shape change resulting from a temperature-induced phase transformation. The utilization of a reversible trigonal (R-phase) to cubic phase transformation in NiTiFe SMAs allows for this strain recovery to occur with reduced hysteresis between the forward and reverse transformations. However, the magnitude of the strain recovery associated with the R-phase transformation is lower than that of the monoclinic to cubic phase transformation. The use of helical springs can compensate for this design constraint as they produce significant stroke when compared to straight elements such as thin strips and wires. This work reports on the development and implementation of NiTiFe helical springs in a low-hysteresis thermal conduction switch for advanced spaceport applications associated with NASA's requirements for future lunar and Mars missions. Such a low-hysteresis thermal conduction switch can provide on-demand heat transfer between two reservoirs at different temperatures.

  15. Mode transition and hysteresis in inductively coupled radio frequency argon discharge

    NASA Astrophysics Data System (ADS)

    Wegner, Th.; Küllig, C.; Meichsner, J.

    2016-02-01

    This contribution presents experimental results about the mode transition of an inductively coupled radio frequency (RF) (13.56 MHz) argon discharge at different total gas pressures. In particular, the positive ion saturation current and the line integrated electron density are measured by Langmuir probe and 160 GHz microwave interferometer, respectively. The mode transition strongly depends on the total gas pressure and can appear stepwise or continuously. The space resolved positive ion saturation current is separately shown for the E- and H-mode at different total gas pressures. Therewith, the pressure dependency of the RF sheath thickness indicates a collisional sheath. The hysteresis phenomenon during the E-H and the inverse H-E transition is discussed within the framework of the matching situation for different total gas pressures. The hysteresis width is analyzed using the absorbed power as well as the coil voltage and current. As a result, the width strongly increases with pressure regarding the power and the coil voltage in the E-mode and remains constant in the H-mode. In addition, the phase shift between the coil voltage and current shows a hysteresis effect, too.

  16. Hysteresis Analysis Based on the Ferroelectric Effect in Hybrid Perovskite Solar Cells.

    PubMed

    Wei, Jing; Zhao, Yicheng; Li, Heng; Li, Guobao; Pan, Jinlong; Xu, Dongsheng; Zhao, Qing; Yu, Dapeng

    2014-11-01

    The power conversion efficiency (PCE) of CH3NH3PbX3 (X = I, Br, Cl) perovskite solar cells has been developed rapidly from 6.5 to 18% within 3 years. However, the anomalous hysteresis found in I-V measurements can cause an inaccurate estimation of the efficiency. We attribute the phenomena to the ferroelectric effect and build a model based on the ferroelectric diode to explain it. The ferroelectric effect of CH3NH3PbI3-xClx is strongly suggested by characterization methods and the E-P (electrical field-polarization) loop. The hysteresis in I-V curves is found to greatly depend on the scan range as well as the velocity, which is well explained by the ferroelectric diode model. We also find that the current signals show exponential decay in ?10 s under prolonged stepwise measurements, and the anomalous hysteresis disappears using these stabilized current values. The experimental results accord well with the model based on ferroelectric properties and prove that prolonged stepwise measurement is an effective way to evaluate the real efficiency of perovskite solar cells. Most importantly, this work provides a meaningful perspective that the ferroelectric effect (if it really exists) should be paid special attention in the optimization of perovskite solar cells. PMID:26278773

  17. Water Dynamics and Its Role in Structural Hysteresis of Dissolved Organic Matter.

    PubMed

    Conte, Pellegrino; Kucerik, Jiri

    2016-03-01

    Knowledge of structural dynamics of dissolved organic matter (DOM) is of paramount importance for understanding DOM stability and role in the fate of solubilized organic and inorganic compounds (e.g., nutrients and pollutants), either in soils or aquatic systems. In this study, fast field cycling (FFC) (1)H NMR relaxometry was applied to elucidate structural dynamics of terrestrial DOM, represented by two structurally contrasting DOM models such as Suwanee River (SRFA) and Pahokee peat (PPFA) fulvic acids purchased by the International Humic Substance Society. Measurement of NMR relaxation rate of water protons in heating-cooling cycles revealed structural hysteresis in both fulvic acids. In particular, structural hysteresis was related to the delay in re-establishing water network around fulvic molecules as a result of temperature fluctuations. The experiments revealed that the structural temperature dependency and hysteresis were more pronounced in SRFA than in PPFA. This was attributed to the larger content of hydrogel-like structure in SRFA stabilized, at a larger extent, by H-bonds between carboxylic and phenolic groups. Moreover, results supported the view that terrestrial DOM consist of a hydrophobic rigid core surrounded by progressively assembling amphiphilic and polar molecules, which form an elastic structure that can mediate reactivity of the whole DOM. PMID:26815011

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

    PubMed

    Hergt, Rudolf; Dutz, Silvio; Rder, Michael

    2008-09-24

    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 100nm. 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. PMID:21693832

  19. A reduced-order model from high-dimensional frictional hysteresis

    PubMed Central

    Biswas, Saurabh; Chatterjee, Anindya

    2014-01-01

    Hysteresis in material behaviour includes both signum nonlinearities as well as high dimensionality. Available models for component-level hysteretic behaviour are empirical. Here, we derive a low-order model for rate-independent hysteresis from a high-dimensional massless frictional system. The original system, being given in terms of signs of velocities, is first solved incrementally using a linear complementarity problem formulation. From this numerical solution, to develop a reduced-order model, basis vectors are chosen using the singular value decomposition. The slip direction in generalized coordinates is identified as the minimizer of a dissipation-related function. That function includes terms for frictional dissipation through signum nonlinearities at many friction sites. Luckily, it allows a convenient analytical approximation. Upon solution of the approximated minimization problem, the slip direction is found. A final evolution equation for a few states is then obtained that gives a good match with the full solution. The model obtained here may lead to new insights into hysteresis as well as better empirical modelling thereof. PMID:24910522

  20. 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

  1. 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.

  2. 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.

  3. Thin three-dimensional droplets on an oscillating substrate with contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Bradshaw, J.; Billingham, J.

    2016-01-01

    Recent experiments [P. Brunet, J. Eggers, and R. D. Deegan, Phys. Rev. Lett. 99, 144501 (2007), 10.1103/PhysRevLett.99.144501] have shown that a liquid droplet on an inclined plane can be made to move uphill by sufficiently strong, vertical oscillations. In order to investigate this counterintuitive phenomenon we use a model in which liquid inertia and viscosity are assumed negligible so that the motion of the droplet is dominated by the applied acceleration due to the oscillation of the plate, gravity, and surface tension. We explain how the leading order motion of the droplet can be separated into a spreading mode and a swaying mode. For a linear contact line law, the maximum rise velocity occurs when these modes are in phase. We show that, both with and without contact angle hysteresis, the droplet can climb uphill and also that, for certain contact line laws, the motion of the droplet can produce footprints similar to experimental results. We show that if the two modes are out of phase when there is no contact angle hysteresis, the inclusion of hysteresis can force them into phase. This in turn increases the rise velocity of the droplet and can, in some cases, cause a sliding droplet to climb.

  4. 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

  5. Hysteresis Effects in Ag-Doped Superconducting Y-Ba-Cu-O

    NASA Astrophysics Data System (ADS)

    Altinkok, Atilgan; Kilic, Kivilcim; Kilic, Atilla; Olutas, Murat; Yetis, Hakan

    2009-03-01

    Time and hysteresis effects have been studied by magneto-voltage (V-H curves) measurements in Ag doped sample of YBa2Cu3O7-x (YBCO/Ag) as functions of transport current (I), sweep rate of external magnetic field (dH/dt) and temperature. Ag was added in the amount of 3% of nominal composition of Cu in YBCO. It was observed that the dissipation in V-H curves does not change as dH/dt increases. This suggests that Ag doping destroys the weak-link structure along inter-grain boundaries and thus the vortices can find enough time to move in the sample irrespective of varying of external H. .The hysteresis effects in V-H curves ride on a background voltage at the temperatures near the Tc. In one hand, the background voltage of V-H curves decreases by taking low values as the temperature decreases, in the other hand, the hysteresis effects become more significant. It was observed that the evolution of V-H curves depends also on the magnitude of transport current. The increase in I causes a considerable enhancement in background voltage in V-H curves. Similar measurements were repeated for YBCO sample without Ag for a comparison. Experimental observations between YBCO/Ag and YBCO establish that adding of Ag into the superconducting matrix causes the formation of easy metallic flow paths for vortices and thus easy distribution of vortices along grain boundaries.

  6. Feedforward Controller of Ill-Conditioned Hysteresis Using Singularity-Free PrandtlIshlinskii Model

    PubMed Central

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

    2009-01-01

    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 PrandtlIshlinskii (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

  7. Modeling of Rate-Dependent Hysteresis Using a GPO-Based Adaptive Filter.

    PubMed

    Zhang, Zhen; Ma, Yaopeng

    2016-01-01

    A novel generalized play operator-based (GPO-based) nonlinear adaptive filter is proposed to model rate-dependent hysteresis nonlinearity for smart actuators. In the proposed filter, the input signal vector consists of the output of a tapped delay line. GPOs with various thresholds are used to construct a nonlinear network and connected with the input signals. The output signal of the filter is composed of a linear combination of signals from the output of GPOs. The least-mean-square (LMS) algorithm is used to adjust the weights of the nonlinear filter. The modeling results of four adaptive filter methods are compared: GPO-based adaptive filter, Volterra filter, backlash filter and linear adaptive filter. Moreover, a phenomenological operator-based model, the rate-dependent generalized Prandtl-Ishlinskii (RDGPI) model, is compared to the proposed adaptive filter. The various rate-dependent modeling methods are applied to model the rate-dependent hysteresis of a giant magnetostrictive actuator (GMA). It is shown from the modeling results that the GPO-based adaptive filter can describe the rate-dependent hysteresis nonlinear of the GMA more accurately and effectively. PMID:26861349

  8. 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.

  9. Effect of Hysteresis on Measurements of Thin-Film Cell Performance

    SciTech Connect

    Albin, D.; del Cueto, J.

    2011-03-01

    Transient or hysteresis effects in polycrystalline thin film CdS/CdTe cells are a function of pre-measurement voltage bias and whether Cu is introduced as an intentional dopant during back contact fabrication. When Cu is added, the current-density (J) vs. voltage (V) measurements performed in a reverse-to-forward voltage direction will yield higher open-circuit voltage (Voc), up to 10 mV, and smaller short-circuit current density (Jsc), by up to 2 mA/cm2, relative to scanning voltage in a forward-to-reverse direction. The variation at the maximum power point, Pmax, is however small. The resulting variation in FF can be as large as 3%. When Cu is not added, hysteresis in both Voc and Jsc is negligible however Pmax hysteresis is considerably greater. This behavior corroborates observed changes in depletion width, Wd, derived from capacitance (C) vs voltage (V) scans. Measured values of Wd are always smaller in reverse-to-forward voltage scans, and conversely, larger in the forward-to-reverse voltage direction. Transient ion drift (TID) measurements performed on Cu-containing cells do not show ionic behavior suggesting that capacitance transients are more likely due to electronic capture-emission processes. J-V curve simulation using Pspice shows that increased transient capacitance during light-soak stress at 100 degrees C correlates with increased space-charge recombination. Voltage-dependent collection however was not observed to increase with stress in these cells.

  10. Significance of conservative asparagine residues in the thermal hysteresis activity of carrot antifreeze protein.

    PubMed Central

    Zhang, Dang-Quan; Liu, Bing; Feng, Dong-Ru; He, Yan-Ming; Wang, Shu-Qi; Wang, Hong-Bin; Wang, Jin-Fa

    2004-01-01

    The approximately 24-amino-acid leucine-rich tandem repeat motif (PXXXXXLXXLXXLXLSXNXLXGXI) of carrot antifreeze protein comprises most of the processed protein and should contribute at least partly to the ice-binding site. Structural predictions using publicly available online sources indicated that the theoretical three-dimensional model of this plant protein includes a 10-loop beta-helix containing the approximately 24-amino-acid tandem repeat. This theoretical model indicated that conservative asparagine residues create putative ice-binding sites with surface complementarity to the 1010 prism plane of ice. We used site-specific mutagenesis to test the importance of these residues, and observed a distinct loss of thermal hysteresis activity when conservative asparagines were replaced with valine or glutamine, whereas a large increase in thermal hysteresis was observed when phenylalanine or threonine residues were replaced with asparagine, putatively resulting in the formation of an ice-binding site. These results confirmed that the ice-binding site of carrot antifreeze protein consists of conservative asparagine residues in each beta-loop. We also found that its thermal hysteresis activity is directly correlated with the length of its asparagine-rich binding site, and hence with the size of its ice-binding face. PMID:14531728

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

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

  13. Modeling of galfenol bending actuator considering nonlinear hysteresis and dynamic real-time control strategy

    NASA Astrophysics Data System (ADS)

    Shu, Liang; Wu, Guichu; Chen, Dingfang; Dapino, Marcelo J.

    2016-03-01

    On active bending structures, the actuation direction and the excitation field direction are not the same. Simple lumped parameter models are inadequate to describe the relationship between output displacement and input field. In this paper, a dynamic distributed parameter model is presented to describe the system dynamics of a galfenol bending actuator. To consider nonlinearities and hysteresis in bending, a nonlinear magnetomechanical model is developed to characterize the hysteretic magnetostriction generated by the galfenol layer. A dynamic real-time control strategy is proposed to compensate for hysteresis. A nonlinear inverse filter is constructed to linearize the hysteresis based on the proposed distributed parameter model. In order to increase the calculation efficiency, a new iteration method is proposed to calculate the filter. The iteration stepsize of the input field can be adaptively updated according to the inverting error. Simulation results show that significant enhancement of convergence efficiency can be achieved by using the proposed method compared with the existing fixed step size method. Experiments have been conducted to verify the real-time control strategy.

  14. Specific features of magnetic properties of ferrihydrite nanoparticles of bacterial origin: A shift of the hysteresis loop

    NASA Astrophysics Data System (ADS)

    Balaev, D. A.; Krasikov, A. A.; Dubrovskiy, A. A.; Semenov, S. V.; Popkov, S. I.; Stolyar, S. V.; Iskhakov, R. S.; Ladygina, V. P.; Yaroslavtsev, R. N.

    2016-02-01

    The results of the experimental investigation into the magnetic hysteresis of systems of superparamagnetic ferrihydrite nanoparticles of bacterial origin have been presented. The hysteresis properties of these objects are determined by the presence of an uncompensated magnetic moment in antiferromagnetic nanoparticles. It has been revealed that, under the conditions of cooling in an external magnetic field, there is a shift of the hysteresis loop with respect to the origin of the coordinates. These features are associated with the exchange coupling of the uncompensated magnetic moment and the antiferromagnetic "core" of the particles, as well as with processes similar to those responsible for the behavior of minor hysteresis loops due to strong local anisotropy fields of the ferrihydrite nanoparticles.

  15. Charging of superconducting layers and resonance-related hysteresis in the current-voltage characteristics of coupled Josephson junctions

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Gaafar, M. A.

    2011-09-01

    A manifestation of a resonance-type hysteresis related to the parametric resonance in the system of coupled Josephson junctions is demonstrated. In contrast with the McCumber and Steward hysteresis, we find that the width of this hysteresis is inversely proportional to the McCumber parameter and it also depends on the coupling between junctions and the boundary conditions. Investigation of the time dependence of the electric charge in superconducting layers allows us to explain the origin of this hysteresis by different charge dynamics for increasing and decreasing bias current processes. The effect of the wavelength of the longitudinal plasma wave created at the resonance on the charging of superconducting layers is demonstrated. We find a strong effect of the dissipation in the system on the amplitude of the charge oscillations at the resonance.

  16. Influence of capillary pressure and trapping hysteresis on large-scale CO2-migration

    NASA Astrophysics Data System (ADS)

    Gasda, S. E.; du Plessis, E.; Nordbotten, J. M.; Dahle, H.

    2013-12-01

    Long-term, subsurface storage of CO2 has been proposed as a key component in stemming global climate change, with potential large-scale storage sites found in saline aquifers worldwide. Previous computational studies of large-scale storage have included vertical equilibrium (VE) model formulations which take advantage of the aquifer geometry to derive two-dimensional models that require less computational effort than their fully three-dimensional counterparts. Earlier VE studies of long-term CO2 storage have taken various complexities into account. For example, including a capillary fringe at the interface between CO2 and brine can lead to significant effects on the injected CO2 plume. To date, the developments have stopped short of capturing full hysteresis in the capillary pressure functions. However, excluding hysteresis may lead to over-estimation of residual trapping where a capillary fringe is present. These effects become increasingly important when considering large-scale migration and storage-efficiency, where minor fine scale trapping estimation errors could have a greater effect on the large-scale estimates. The inclusion of full hysteresis in a VE-formulation adds significant complexity, which also increases the computational effort required in a full-scale simulation. The additional cost is due to numerical integration of the capillary pressure functions and other model parameters, which must also be periodically updated during the simulation. In this study, effects of capillary pressure hysteresis on the shape, speed and extent of an advancing CO2 plume, as well as the amount of residually trapped CO2, are studied in a two-dimensional homogeneous sloping aquifer. We investigate the effects of the number of drainage and imbibition cycles included in the model. The example cases represent a sequence of CO2 and brine injections, i.e. a WAG-like scenario, where fine scale residual trapping profiles become important as new injection plumes are subject to decreased mobility when encountering areas already containing trapped CO2. The results indicate that the most important hysteresis process in a two-dimensional setting is the initial reversal from drainage to imbibition which creates a spatially heterogeneous profile of residually trapped CO2. This affects the upscaled mobility of the following injection cycles in a more complex manner than previously predicted.

  17. Effects of temperature ramp rate during heat treatment on hysteresis loss and critical current density of internal tin processed wires

    SciTech Connect

    Suenaga, M.; Sabatini, R.L.

    1995-04-01

    It has been shown that temperature ramp rates utilized in heat treatment schedules for internal tin processed Nb{sub 3}Sn wires substantially influence both hysteresis loss and critical current density J{sub c} of the wires, i.e. a slow ramp rate (e.g. 6{degree}C/h) favors a higher J{sub c} while a fast ramp (e.g. 60{degree}C/h)results in a low hysteresis loss of the wire.

  18. pH sensitivity and hysteresis of A-WO3 gate ISFET compared with different membranes

    NASA Astrophysics Data System (ADS)

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

    1999-11-01

    Because of the pH sensitivity is one of the important characteristic parameters of ISFET devices. The response of ISFET is mainly determined with the type of the sensing membrane, therefore the sensing material plays a significant role. In addition, the hysteresis is the non-ideal and unstable factor of ISFET devices for measuring. Hence, in this study, the pH sensitivity and hysteresis of a-WO3 gate ISFET are investigated, and compare with different sensing membranes.

  19. Effects of Control Hysteresis on the Space Shuttle Orbiter's Entry. M.S. Thesis - George Washington Univ.

    NASA Technical Reports Server (NTRS)

    Powell, R. W.

    1975-01-01

    There are six degree-of-freedom simulations of the space shuttle orbiter entry with aerodynamic control hysteresis conducted on the NASA Langley Research Center interactive simulator known as the Automatic Reentry Flight Dynamics Simulator. These were performed to determine if the presence of aerodynamic control hysteresis would endanger the mission, either by making the vehicle unable to maintain proper attitude for a safe entry, or by increasing the amount of the reaction control system's fuel consumption beyond that carried.

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

    NASA Astrophysics Data System (ADS)

    Fraedrich, K.

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Gimnez, Rafael; Casal, Javier; Dez, Javier; Goi, 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 Tejera and Latxaga) and 2001 (Oskotz "principal", Op, and Oskotz "woodland", Ow). La Tejera 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 Tejera, 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 Tejera this rate was only 50%. Also, the hysteresis in Op/Ow and Laxtaga was more clearly defined (a higher index) than that in La Tejera. 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.

  2. 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

  3. 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 20092010 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Landers, Mark N.; Sturm, Terry W.

    2013-09-01

    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 dataset 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 µm). This study shows that small changes in the often assumed stability of the PSD are significant to SSC˜T relations. Changes of only 5 µm 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.

  6. Force of adhesion upon loss of contact angle hysteresis: when a liquid behaves like a solid.

    PubMed

    Escobar, Juan V; Castillo, Rolando

    2013-11-27

    The theoretically predicted vanishment of the macroscopic contact angle hysteresis is found experimentally along with a small but finite force of adhesion (F(Ad)?-0.5 ?N) that, unexpectedly, is independent of the history of the preload. Our results agree with the prediction of a model in which the surface tension of the liquid provides the counterpart of the restoring force of an elastic solid, evidencing that the dewetting of a liquid in the absence of strong pinning points is equivalent to the detachment of an elastic solid. PMID:24329459

  7. Force of Adhesion Upon Loss of Contact Angle Hysteresis: When a Liquid Behaves Like a Solid

    NASA Astrophysics Data System (ADS)

    Escobar, Juan V.; Castillo, Rolando

    2013-11-01

    The theoretically predicted vanishment of the macroscopic contact angle hysteresis is found experimentally along with a small but finite force of adhesion (FAd?-0.5?N) that, unexpectedly, is independent of the history of the preload. Our results agree with the prediction of a model in which the surface tension of the liquid provides the counterpart of the restoring force of an elastic solid, evidencing that the dewetting of a liquid in the absence of strong pinning points is equivalent to the detachment of an elastic solid.

  8. Flux Flow, Phase Slip and Hysteresis in DC Resistivity of - and Intra-Grain Regions

    NASA Astrophysics Data System (ADS)

    Hasanain, S. K.; Asim, M. M.

    The effects of flux flow, phase slip and flux redistribution between inter- and intra-grain regions are investigated via dc resistivity of a zerofield cooled granular superconductor. Differences between the low H (HHc1) behavior are explained in terms of differing pinning strengths of inter- and intra-grain regions. A minimum in ρ(θ) (θ: angle between H and J) and hysteresis effects are observed and explained via flux redistribution between grains and intergrain regions.

  9. Influence of fourfold anisotropy form on hysteresis loop shape in ferromagnetic nanostructures

    SciTech Connect

    Ehrmann, Andrea; Blachowicz, Tomasz

    2014-08-15

    The dependence of the form of different mathematical depictions of fourfold magnetic anisotropies has been examined, using a simple macro-spin model. Strong differences in longitudinal and transverse hysteresis loops occur due to deviations from the usual phenomenological model, such as using absolute value functions. The proposed possible models can help understanding measurements on sophisticated magnetic nanosystems, like exchange bias layered structures employed in magnetic hard disk heads or magnetic nano-particles, and support the development of solutions with specific magnetization reversal behavior needed in novel magneto-electronic devices.

  10. ac Dynamics of Ferroelectric Domains from an Investigation of the Frequency Dependence of Hysteresis Loops

    SciTech Connect

    Yang, Sang Mo; Jo, Ji Young; Kim, T. H.; Yoon, J. -G.; Song, T. K.; Lee, Ho Nyung; Marton, Zsolt; Park, S.; Jo, Y.; Noh, Tae Won

    2010-01-01

    We investigated nonequilibrium domain wall dynamics under an ac field by measuring the hystere- sis loops of epitaxial ferroelectric capacitors at various frequencies and temperatures. Polarization switching is induced mostly by thermally activated creep motion at lower frequencies, and by vis- cous ow motion at higher frequencies. The dynamic crossover between the creep and ow regimes unveils two frequency-dependent scaling regions of hysteresis loops. Based on these findings, we constructed a dynamic phase diagram for hysteretic ferroelectric domain dynamics in the presence of ac fields.

  11. Multifluid squirt flow and hysteresis effects on the bulk modulus-water saturation relationship

    NASA Astrophysics Data System (ADS)

    Papageorgiou, G.; Chapman, M.

    2015-11-01

    Many applications of seismology require the calculation of wave speed and attenuation in rocks saturated with multiple fluids. Squirt flow is known to be an important effect in fully saturated rocks but the extension to the multifluid case is unclear. Neglecting capillary effects, we generalize previous work on squirt flow to the case where two fluids are present. We derive expressions for the effective fluid properties, but the results depend on the spatial distributions, and not only volume fractions, of the two fluids. Our results demonstrate that such multifluid squirt flow may be responsible for hysteresis effects in elastic properties during imbibition and drainage.

  12. Gas flow across a wet screen - Analogy to a relief valve with hysteresis

    NASA Technical Reports Server (NTRS)

    Nachman, A.; Dodge, F. T.

    1983-01-01

    The flow of gas through a wet fine-mesh screen is analyzed in terms of the capillary forces of the liquid wetting the screen and the pressure difference across the screen thickness driving the gas flow. Several different types of time-dependent flow are shown to be possible. The most interesting type is one in which the pressure difference opens small channels in the liquid, which are then closed rapidly by the wetting action of the liquid. The opening and closing exhibit hysteresis, and the flow is highly oscillatory.

  13. Hysteresis and creep: Comparison between a power-law model and Kuhnen's model

    NASA Astrophysics Data System (ADS)

    Oliveri, Alberto; Stellino, Flavio; Parodi, Mauro; Storace, Marco

    2016-04-01

    In this paper we analyze some properties of a recently proposed model of hysteresis and creep (related to a circuit model, whose only nonlinear element is based on a power law) and compare it with the well-known Kuhnen's model. A first qualitative comparison relies on the analysis of the behavior of the elementary cell of each model. Their responses to step inputs (which allow to better evidence the creep effect) are analyzed and compared. Then, a quantitative comparison is proposed, based on the fitting performances of the two models on experimental data measured from a commercial piezoelectric actuator.

  14. 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.

  15. Optically induced hysteresis in a two-state quantum dot laser.

    PubMed

    Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Dubinkin, I; Fedorov, N; Erneux, T; Viktorov, E A; Kelleher, B

    2016-03-01

    Quantum dot lasers can lase from the ground state only, simultaneously from both the ground and first excited states and from the excited state only. We examine the influence of optical injection at frequencies close to the ground state when the free-running operation of the device is excited state lasing only. We demonstrate the existence of an injection-induced bistability between ground state dominated emission and excited state dominated emission and the consequent hysteresis loop in the lasing output. Experimental and numerical investigations are in excellent agreement. Inhomogeneous broadening is found to be the underlying physical mechanism driving the phenomenon. PMID:26974109

  16. Hysteresis and memory factor of the Kerr effect in blue phases

    NASA Astrophysics Data System (ADS)

    Nordendorf, Gaby; Lorenz, Alexander; Hoischen, Andreas; Schmidtke, Jrgen; Kitzerow, Heinz; Wilkes, David; Wittek, Michael

    2013-11-01

    The performance of a polymer-stabilized blue phase system based on a nematic host with large dielectric anisotropy and a chiral dopant with high helical twisting power is investigated and the influence of the reactive monomer composition on the electro-optic characteristics is studied. Field-induced birefringence with a Kerr coefficient greater than 1 nm V-2 can be achieved in a large temperature range from well below 20 C to above 55 C. The disturbing influences of electro-optic hysteresis and memory effects can be reduced by diligent choice of the composition and appropriate electric addressing.

  17. Correlation between the hysteresis and the initial defect density of graphene

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

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

    PubMed

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

    2015-08-24

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

  19. PREFACE: 6th International Workshop on Multi-Rate Processes and Hysteresis (MURPHYS2012)

    NASA Astrophysics Data System (ADS)

    Dimian, Mihai; Rachinskii, Dmitrii

    2015-02-01

    The International Workshop on Multi-Rate Processes and Hysteresis (MURPHYS) conference series focuses on multiple scale systems, singular perturbation problems, phase transitions and hysteresis phenomena occurring in physical, biological, chemical, economical, engineering and information systems. The 6th edition was hosted by Stefan cel Mare University in the city of Suceava located in the beautiful multicultural land of Bukovina, Romania, from May 21 to 24, 2012. This continued the series of biennial multidisciplinary conferences organized in Cork, Ireland from 2002 to 2008 and in Pécs, Hungary in 2010. The MURPHYS 2012 Workshop brought together more than 50 researchers in hysteresis and multi-scale phenomena from the United State of America, the United Kingdom, France, Germany, Italy, Ireland, Czech Republic, Hungary, Greece, Ukraine, and Romania. Participants shared and discussed new developments of analytical techniques and numerical methods along with a variety of their applications in various areas, including material sciences, electrical and electronics engineering, mechanical engineering and civil structures, biological and eco-systems, economics and finance. The Workshop was sponsored by the European Social Fund through Sectoral Operational Program Human Resources 2007-2013 (PRO-DOCT) and Stefan cel Mare University, Suceava. The Organizing Committee was co-chaired by Mihai Dimian from Stefan cel Mare University, Suceava (Romania), Amalia Ivanyi from the University of Pecs (Hungary), and Dmitrii Rachinskii from the University College Cork (Ireland). 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 Guest Editors wish to place on record their sincere gratitude to Miss Sarah Toms for the assistance she provided during the publication process. More information about the Workshop can be found at http://www.murphys.usv.ro/ Mihai Dimian and Dmitrii Rachinskii Guest Editors for Journal of Physics: Conference Series Proceedings of the 6th International Workshop on Multi-Rate Processes and Hysteresis

  20. AC electrical transport properties and current-voltage hysteresis behavior of PVA-CNT nanocomposite film

    NASA Astrophysics Data System (ADS)

    Das, Amit Kumar; Sinha, Subhojyoti; Meikap, Ajit Kumar

    2015-06-01

    Polyvinyl alcohol (PVA) - Carbon nanotube (CNT) composite has been prepared and its electric modulus, ac conductivity, impedance spectroscopy and current-voltage characteristics have been studied, at and above room temperature, to understand the prevailing charge transport mechanism. Non-Debye type relaxation behavior was observed with activation energy of 1.27 eV whereas correlated barrier hopping was found to be the dominant charge transport mechanism with maximum barrier height of 48.7 meV above room temperature. The sample, under ±80 V applied voltage, exhibits hysteresis behavior in its current - voltage characteristics.

  1. A time-delay calibrated method for cornea hysteresis and intraocular pressure measurement

    NASA Astrophysics Data System (ADS)

    Wang, Kuo-Jen; Tsai, Che-Liang; Wang, Wai; Hsu, Long; Hsu, Ken-Yuh

    2015-12-01

    The presence of cornea hysteresis (CH) in characterizing the intraocular pressure (IOP) of a human eye deteriorates the accuracy of IOP. To suppress CH, the pressure gauge of a tonometer must be located as close as possible to the cornea. However, this arrangement is unpractical because appropriate working distance to the cornea is required. In this paper, a time-delay calibrated (TDC) method is proposed to counteract the undesired effect of CH in characterizing the IOP. Employing this TDC method, the CH approaches to zero for most eyes measured.

  2. Modeling and inverse compensation of hysteresis in vanadium dioxide using an extended generalized Prandtl-Ishlinskii model

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Merced, Emmanuelle; Seplveda, Nelson; Tan, Xiaobo

    2014-12-01

    Vanadium dioxide (V{{O}2}), a promising multifunctional smart material, has shown strong promise in microactuation, memory, and optical applications. During thermally induced insulator-to-metal phase transition of V{{O}2}, the changes of its electrical, mechanical, and optical properties demonstrate pronounced, complex hysteresis with respect to the temperature, which presents a challenge in the utilization of this material. In this paper, an extended generalized Prandtl-Ishlinskii model is proposed to model the hysteresis in V{{O}2}, where a nonlinear memoryless function is introduced to improve its modeling capability. A novel inverse compensation algorithm for this hysteresis model is developed based on fixed-point iteration with which the convergence conditions of the algorithm are derived. The proposed approach is shown to be effective for modeling and compensating the asymmetric and non-monotonic hysteresis with saturation between the curvature output and the temperature input of a V{{O}2}-coated microactuator, as well as the asymmetric hysteresis with partial saturation between the resistance output and the temperature input of a V{{O}2} film.

  3. Utilizing avidity to improve antifreeze protein activity: a type III antifreeze protein trimer exhibits increased thermal hysteresis activity.

    PubMed

    Can, Özge; Holland, Nolan B

    2013-12-01

    Antifreeze proteins (AFPs) are ice growth inhibitors that allow the survival of several species living at temperatures colder than the freezing point of their bodily fluids. AFP activity is commonly defined in terms of thermal hysteresis, which is the difference observed for the solution freezing and melting temperatures. Increasing the thermal hysteresis activity of these proteins, particularly at low concentrations, is of great interest because of their wide range of potential applications. In this study, we have designed and expressed one-, two-, and three-domain antifreeze proteins to improve thermal hysteresis activity through increased binding avidity. The three-domain type III AFP yielded significantly greater activity than the one- and two-domain proteins, reaching a thermal hysteresis of >1.6 °C at a concentration of <1 mM. To elucidate the basis of this increase, the data were fit to a multidomain protein adsorption model based on the classical Langmuir isotherm. Fits of the data to the modified isotherms yield values for the equilibrium binding constants for the adsorption of AFP to ice and indicate that protein surface coverage is proportional to thermal hysteresis activity. PMID:24191717

  4. Sensitivity and hysteresis behavior of the commercial Sentron 1090 Al2O3 gate pH-ISFET

    NASA Astrophysics Data System (ADS)

    Chou, Jung Chuan; Weng, Chen Yu

    2000-07-01

    In this study, we utilize the commercial device, Sentron 1090 Al2O3 gate pH-ISFET to study the sensitivity and hysteresis behaviour. The experimental results show that the Al2O3 materials have a fairly high response, and the sensitivity was obtained from the pH response of Sentron 1090. The hysteresis effect in a Sentron 1090 Al2O3 gate pH-ISFET was studied by exposing the device to two cycles of pH values. The hysteresis curves were measured in the sequence pH 8-3-8-11-8 and pH 7-3-7-11-7 at different loop time. According to experimental results, the hysteresis width is increasing with loop time and measuring path. We also observed and compared the pH sensitivity and magnitude of the hysteresis width with others pH-sensing gate ISFETs studied in our laboratory and the related literatures.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  6. Storm Event Suspended Sediment-Discharge Hysteresis and Controls in Agricultural Watersheds: Implications for Watershed Scale Sediment Management.

    PubMed

    Sherriff, Sophie C; Rowan, John S; Fenton, Owen; Jordan, Philip; Melland, Alice R; Mellander, Per-Erik; hUallacháin, Daire Ó

    2016-02-16

    Within agricultural watersheds suspended sediment-discharge hysteresis during storm events is commonly used to indicate dominant sediment sources and pathways. However, availability of high-resolution data, qualitative metrics, longevity of records, and simultaneous multiwatershed analyses has limited the efficacy of hysteresis as a sediment management tool. This two year study utilizes a quantitative hysteresis index from high-resolution suspended sediment and discharge data to assess fluctuations in sediment source location, delivery mechanisms and export efficiency in three intensively farmed watersheds during events over time. Flow-weighted event sediment export was further considered using multivariate techniques to delineate rainfall, stream hydrology, and antecedent moisture controls on sediment origins. Watersheds with low permeability (moderately- or poorly drained soils) with good surface hydrological connectivity, therefore, had contrasting hysteresis due to source location (hillslope versus channel bank). The well-drained watershed with reduced connectivity exported less sediment but, when watershed connectivity was established, the largest event sediment load of all watersheds occurred. Event sediment export was elevated in arable watersheds when low groundcover was coupled with high connectivity, whereas in the grassland watershed, export was attributed to wetter weather only. Hysteresis analysis successfully indicated contrasting seasonality, connectivity and source availability and is a useful tool to identify watershed specific sediment management practices. PMID:26784287

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

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

    2013-07-01

    A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator. PMID:23902095

  9. Cryotherapy-Induced Persistent Vasoconstriction After Cutaneous Cooling: Hysteresis Between Skin Temperature and Blood Perfusion.

    PubMed

    Khoshnevis, Sepideh; Craik, Natalie K; Matthew Brothers, R; Diller, Kenneth R

    2016-03-01

    The goal of this study was to investigate the persistence of cold-induced vasoconstriction following cessation of active skin-surface cooling. This study demonstrates a hysteresis effect that develops between skin temperature and blood perfusion during the cooling and subsequent rewarming period. An Arctic Ice cryotherapy unit (CTU) was applied to the knee region of six healthy subjects for 60 min of active cooling followed by 120 min of passive rewarming. Multiple laser Doppler flowmetry perfusion probes were used to measure skin blood flow (expressed as cutaneous vascular conductance (CVC)). Skin surface cooling produced a significant reduction in CVC (P < 0.001) that persisted throughout the duration of the rewarming period. In addition, there was a hysteresis effect between CVC and skin temperature during the cooling and subsequent rewarming cycle (P < 0.01). Mixed model regression (MMR) showed a significant difference in the slopes of the CVC-skin temperature curves during cooling and rewarming (P < 0.001). Piecewise regression was used to investigate the temperature thresholds for acceleration of CVC during the cooling and rewarming periods. The two thresholds were shown to be significantly different (P = 0.003). The results show that localized cooling causes significant vasoconstriction that continues beyond the active cooling period despite skin temperatures returning toward baseline values. The significant and persistent reduction in skin perfusion may contribute to nonfreezing cold injury (NFCI) associated with cryotherapy. PMID:26632263

  10. Role of contact-angle hysteresis for fluid transport in wet granular matter.

    PubMed

    Mani, Roman; Semprebon, Ciro; Kadau, Dirk; Herrmann, Hans J; Brinkmann, Martin; Herminghaus, Stephan

    2015-04-01

    The stability of sand castles is determined by the structure of wet granulates. Experimental data on the size distribution of fluid pockets are ambiguous with regard to their origin. We discovered that contact-angle hysteresis plays a fundamental role in the equilibrium distribution of bridge volumes, and not geometrical disorder as commonly conjectured. This has substantial consequences on the mechanical properties of wet granular beds, including a history-dependent rheology and lowered strength. Our findings are obtained using a model in which the Laplace pressures, bridge volumes, and contact angles are dynamical variables associated with the contact points. While accounting for contact line pinning, we track the temporal evolution of each bridge. We observe a crossover to a power-law decay of the variance of capillary pressures at late times and a saturation of the variance of bridge volumes to a finite value connected to contact line pinning. Large-scale simulations of liquid transport in the bridge network reveal that the equilibration dynamics at early times is well described by a mean-field model. The spread of final bridge volumes can be directly related to the magnitude of contact-angle hysteresis. PMID:25974481

  11. Role of contact-angle hysteresis for fluid transport in wet granular matter

    NASA Astrophysics Data System (ADS)

    Mani, Roman; Semprebon, Ciro; Kadau, Dirk; Herrmann, Hans J.; Brinkmann, Martin; Herminghaus, Stephan

    2015-04-01

    The stability of sand castles is determined by the structure of wet granulates. Experimental data on the size distribution of fluid pockets are ambiguous with regard to their origin. We discovered that contact-angle hysteresis plays a fundamental role in the equilibrium distribution of bridge volumes, and not geometrical disorder as commonly conjectured. This has substantial consequences on the mechanical properties of wet granular beds, including a history-dependent rheology and lowered strength. Our findings are obtained using a model in which the Laplace pressures, bridge volumes, and contact angles are dynamical variables associated with the contact points. While accounting for contact line pinning, we track the temporal evolution of each bridge. We observe a crossover to a power-law decay of the variance of capillary pressures at late times and a saturation of the variance of bridge volumes to a finite value connected to contact line pinning. Large-scale simulations of liquid transport in the bridge network reveal that the equilibration dynamics at early times is well described by a mean-field model. The spread of final bridge volumes can be directly related to the magnitude of contact-angle hysteresis.

  12. Energy dissipation due to viscosity during deformation of a capillary surface subject to contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Athukorallage, Bhagya; Iyer, Ram

    2014-02-01

    A capillary surface is the boundary between two immiscible fluids. When the two fluids are in contact with a solid surface, there is a contact line. The physical phenomena that cause dissipation of energy during a motion of the contact line are hysteresis in the contact angle dynamics, and viscosity of the fluids involved. In this paper, we consider a simplified problem where a liquid and a gas are bounded between two parallel plane surfaces with a capillary surface between the liquid-gas interface. The liquid-plane interface is considered to be non-ideal, which implies that the contact angle of the capillary surface at the interface is set-valued, and change in the contact angle exhibits hysteresis. We analyze a two-point boundary value problem for the fluid flow described by the Navier-Stokes and continuity equations, wherein a capillary surface with one contact angle is deformed to another with a different contact angle. The main contribution of this paper is that we show the existence of non-unique classical solutions to this problem, and numerically compute the dissipation.

  13. Abnormal Current-Voltage Hysteresis Induced by Reverse Bias in Organic-Inorganic Hybrid Perovskite Photovoltaics.

    PubMed

    Rajagopal, Adharsh; Williams, Spencer T; Chueh, Chu-Chen; Jen, Alex K-Y

    2016-03-17

    In this study, reverse bias (RB)-induced abnormal hysteresis is investigated in perovskite solar cells (PVSCs) with nickel oxide (NiOx)/methylammonium lead iodide (CH3NH3PbI3) interfaces. Through comprehensive current-voltage (I-V) characterization and bias-dependent external quantum efficiency (EQE) measurements, we demonstrate that this phenomenon is caused by the interfacial ion accumulation intrinsic to CH3NH3PbI3. Subsequently, via systematic analysis we discover that the abnormal I-V behavior is remarkably similar to tunnel diode I-V characteristics and is due to the formation of a transient tunnel junction at NiOx/CH3NH3PbI3 interfaces under RB. The detailed analysis navigating the complexities of I-V behavior in CH3NH3PbI3-based solar cells provided here ultimately illuminates possibilities in modulating ion motion and hysteresis via interfacial engineering in PVSCs. Furthermore, this work shows that RB can alter how CH3NH3PbI3 contributes to the functional nature of devices and provides the first steps toward approaching functional perovskite interfaces in new ways for metrology and analysis of complex transient processes. PMID:26927828

  14. Ferromagnetism, hysteresis and enhanced heat dissipation in assemblies of superparamagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Vanchna; Banerjee, Varsha

    2012-12-01

    In this paper, we develop theoretical frameworks to explain the emergence of ferromagnetism in suspensions and agglomerates of superparamagnetic (SPM) nanoparticles. In the limit of strong anisotropy, the super moments can be treated as a collection of two-state Ising spins. When adequate in number, they interact via dipole-dipole coupling to produce a dipolar field and subsequently a permanent dipole moment. As a result, this effectual ferromagnet exhibits hysteresis on the application of an oscillating magnetic field yielding heat dissipation that is several orders of magnitude larger than in a paramagnet. Using our frameworks, we provide a design for a magnetite-blood suspension that yields heat dissipation in the mW range. Its important physical application is in remedial procedures for destroying tumor and cancer cells. We are also able to explain many experiments reporting manifestations of ferromagnetism in the form of hysteresis loops, return point memory and large heat dissipation in suspensions and aggregates of SPM nanoparticles. Our frameworks can be used to manipulate heat dissipation in variety of combinations of particles and their embedding mediums. They impart a basis to the often used ad-hoc methodologies in this subject.

  15. Crystal growth and dynamic ferroelectric hysteresis scaling behavior of molecular ferroelectric diisopropylammonium bromide

    NASA Astrophysics Data System (ADS)

    Jiang, Chunli; Lin, Hechun; Luo, Chunhua; Zhang, Yuanyuan; Yang, Jing; Peng, Hui; Duan, Chun-Gang

    2016-03-01

    The molecular ferroelectric, diisopropylammonium bromide (DIPAB) crystal with P21 phase is successfully prepared in an anhydrous environment at room temperature. The results illustrate that the water in the solvent / environment plays a key role in the phase of DIPAB single crystal during crystallization process. The scaling behavior of the dynamic hysteresis of DIPAB crystal is also investigated. The scaling relations of hysteresis area(A) against frequency (f) and applied electric field amplitude (E0) can be expressed with A ∝ f - 0 . 17E01 in the f-region I (30-6.6 Hz), A ∝ f 0 . 045E00.92 in the f-region II (200-50 Hz) and A ∝ f - 0 . 41E02 in the f-region III (500-250 Hz). This three-stage behavior between the loop area A and frequency is ascribed to the coexistence of order-disorder and displacive characters in the ferroelectric transition characters in such molecular ferroelectrics.

  16. An eddy current vector potential formulation for estimating hysteresis losses of superconductors with FEM

    NASA Astrophysics Data System (ADS)

    Stenvall, A.; Tarhasaari, T.

    2010-12-01

    Many people these days employ only commercial finite element method (FEM) software when solving for the hysteresis losses of superconductors. Thus, the knowledge of a modeller is in the capability of using the black boxes of software efficiently. This has led to a relatively superficial examination of different formulations while the discussion stays mainly on the usage of the user interfaces of these programs. Also, if we stay only at the mercy of commercial software producers, we end up having less and less knowledge on the details of solvers. Then, it becomes more and more difficult to conceptually solve new kinds of problem. This may prevent us finding new kinds of method to solve old problems more efficiently, or finding a solution for a problem that was considered almost impossible earlier. In our earlier research, we presented the background of a co-tree gauged T-phiv FEM solver for computing the hysteresis losses of superconductors. In this paper, we examine the feasibility of FEM and eddy current vector potential formulation in the same problem.

  17. Parameter analysis of PEM fuel cell hysteresis effects for transient load use

    NASA Astrophysics Data System (ADS)

    Talj, R.; Azib, T.; Bthoux, O.; Remy, G.; Marchand, C.; Berthelot, E.

    2011-05-01

    This paper focuses on the hysteresis effect of the polarization characteristics of a polymer electrolyte membrane fuel cell (PEMFC), mainly due to the compressor-air supply system dynamics. Indeed in PEMFC/ultracapacitor hybrid vehicles, fuel cells can be used to supply the low frequencies of the power demand only. First, the different parts of a FC system are described and modeled in order to analyze the transient stack performance decrease and to identify its main influential factors for automotive applications. Then, apart from humidity and temperature variations, each phenomenon is dynamically described, leading to a complete mathematical model based on macroscopic component parameters. Thus, an analytical model based on this set of equations enables us to draw the static voltage versus current FC characteristics. Furthermore, the hysteresis effect on the V-I curve, which still occurs during low dynamic responses, is shown while temperature and humidity are kept constant. Finally, dynamic responses of the Ballard PEMFC Nexa 1200 W generator are analyzed, and detailed experimentation and simulation are carried out for a large magnitude sinusoidal waveform at different frequencies.

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

    SciTech Connect

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

    1986-01-01

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

  19. Magnetization Hysteresis and Quantum Tunneling in Lanthanide Double-Decker Complexes

    NASA Astrophysics Data System (ADS)

    Rupp, H.; Brink, S.

    2005-03-01

    We present magnetization measurements on single crystals of lanthanide double-deckers [Pc2Ln]^- TBA^+. The 4f^9 (4f^8) configuration of the Dy^3+ (Tb^3+), ion results in a J = 15/2 (J = 6) ground-state multiplett. In SQUID measurements on single crystal samples, we observed very large axial and a significant transverse anisotropy. Magnetization measurements using 2DEG ballistic Hall probes were carried out in a ^3He cryostat. Hysteresis was observed for both compounds up to blocking temperatures of 4.2 and >10 K, respectively. The coercivity increased with decreasing temperatures and increasing sweep rate, as expected for the superparamagnet-like behaviour of a SMM. The hysteresis loops displayed step-like features characteristic for resonant quantum tunnelling of the magnetization (QTM). The step height decreased with increasing sweep rate according the Landau-Zener tunnelling mechanism. In conclusion, the lanthanide double decker molecules are SMM with the highest blocking temperatures observed to date.

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

    PubMed

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

    2015-10-01

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

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

    SciTech Connect

    Malkov, M. A.; Diamond, P. H.

    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.

  2. The magnetostriction and its ratio to hysteresis for Tb-Dy-Ho-Fe alloys

    NASA Astrophysics Data System (ADS)

    Wang, Bowen; Lv, Yan; Li, Guolu; Huang, Wenmei; Sun, Ying; Cui, Baozhi

    2014-05-01

    The x(Tb0.15Ho0.85Fe2) + (1 - x)(Tb0.3Dy0.7Fe2) alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon. The static measurement of magnetostriction (?//, ??) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the magnetostriction ?// of x(Tb0.15Ho0.85Fe2) + (1 - x)(Tb0.3Dy0.7Fe2) alloys decreases with increasing x and it does from 880 10-6 for x = 0 to 210 10-6 for x = 0.9 at the magnetic field of 640 kA/m. The ratio (?///Wh) of magnetostriction to hysteresis exhibits a peak when x = 0.1, and it means that the Tb0.285Dy0.63Ho0.085Fe2 (x = 0.1) alloy possesses both large magnetostriction and small magnetostrictive hysteresis.

  3. Hysteresis model and adaptive vibration suppression for a smart beam with time delay

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Li, Hong Guang; Zhong, Zuo Yang; Cai, Guo Ping

    2015-12-01

    This paper mainly presents experimental verifications of vibration suppression for a cantilever beam bonded with a piezoelectric actuator by an adaptive controller. Using the Hamilton Principle and the Bouc-Wen Equation, a dynamical mathematical model is proposed to describe a hysteresis property with different time delay for the smart beam. It is concluded that the hysteresis characteristic of the smart beam is influenced not only by the amplitude and frequency of the input voltage but also by the time delay. Based on the nonlinear model, the adaptive controller with time delay is adopted to attenuate the free vibration of the smart beam. Through some simulations and experiments, the vibration suppression effect can be improved with a proper small time delay in the control system. Moreover, the vibration amplitude attenuation rates at the fundamental frequency with the simulations and the experiments are up to 85.938% and 84.505% respectively. Obviously the adaptive regulator with a proper small time delay is proved to have the capacity of improving the vibration suppression effect.

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

    PubMed

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

    2011-12-01

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

  5. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Graetz, Jason

    2015-03-01

    Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3-4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2=Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid-solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries.

  6. Terfenol-D elastomagnetic properties under varied operating conditions using hysteresis loop analysis

    NASA Astrophysics Data System (ADS)

    Faidley, LeAnn E.; Lund, Brian J.; Flatau, Alison B.; Calkins, Frederick T.

    1998-07-01

    This paper presents an experimental study of the effects of varied magnetic bias, AC magnetic field amplitude and frequency on the characteristics of hysteresis loops produced in a magnetostrictive transducer. The study uses a magnetostrictive transducer designed at Iowa State University that utilizes an 11.5 cm (4.54 in) long by 1.27 cm (0.5 in) diameter cylindrical Terfenol-D rod. This transducer allows controlled variation of the following operating conditions: mechanical prestress, magnitude and frequency of AC magnetic field, and magnetic bias. By performing extensive experimental tests, material property trends can be developed for use in the optimization of transducer design parameters for different applications. For the results presented, the magnetic bias, the AC magnetic field amplitude, and the frequency of excitation were independently varied while temperature, mass load and prestress were kept constant. The minor hysteresis loops of the strain versus applied magnetic field, flux density versus applied magnetic field, and magnetization versus applied magnetic field are presented and compared. Material property trends identified from the minor loops are presented for the axial strain coefficient, permeability, susceptibility, and energy losses.

  7. Annealing condition influences thermal hysteresis of fungal type ice-binding proteins.

    PubMed

    Xiao, Nan; Hanada, Yuichi; Seki, Haruhiko; Kondo, Hidemasa; Tsuda, Sakae; Hoshino, Tamotsu

    2014-02-01

    The Antarctic sea ice diatom Navicular glaciei produced ice-binding protein (NagIBP) that is similar to the antifreeze protein (TisAFP) from snow mold Typhula ishikariensis. In the thermal hysteresis range of NagIBP, ice growth was completely inhibited. At the freezing point, the ice grew in a burst to 6 direction perdicular to the c-axis of ice crystal. This burst pattern is similar to TisAFP and other hyperactive AFPs. The thermal hysteresis of NagIBP and TisAFP could be increased by decreasing a cooling rate to allow more time for the proteins to bind ice. This suggests the possible second binding of proteins occurs on the ice surface, which might increase the hysteresises to a sufficient level to prevent freezing of the brine pockets which habitat of N. glaciei. The secondary ice binding was described as that after AFP molecules bind onto the flat ice plane irreversibly, which was based on adsorption-inhibition mechanism model at the ice-water interface, convex ice front was formed and overgrew during normal TH measurement (no annealing) until uncontrolled growth at the nonequilibrium freezing point. The results suggested that NagIBP is a hyperactive AFP that is expressed for freezing avoidance. PMID:24201106

  8. Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

    SciTech Connect

    Särhammar, Erik Berg, Sören; Nyberg, Tomas

    2014-07-01

    This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

  9. Laminar-Turbulent Transition: A Hysteresis Curve of Two Critical Reynolds Numbers in Pipe Flow

    NASA Astrophysics Data System (ADS)

    Kanda, Hidesada

    2006-11-01

    A laminar-turbulent transition model (DFD 2004) has been constructed for pipe flows: (1) Natural transition occurs in the entrance region, and (2) Entrance shape determines a critical Reynolds number Rc. To verify the model, we have carried out experiments similar to Reynolds's color-dye experiment with 5 bellmouth entrances and a straight pipe. Then, we observed the following: (i) two different types of Rc exist, Rc1 from laminar to turbulent and Rc2 from turbulent to laminar, and (ii) the ratio of bellmouth diameter BD to pipe diameter D affects the values of Rc1 and Rc2. For each entrance, Rc1 has a maximum value Rc1(max) and Rc2 has a minimum value Rc2(min). When overlapping the two curves of Rc1(max) and Rc2(min) against BD/D, a hysteresis curve is confirmed. All Rc values exist inside this hysteresis curve. Consequently, Rc takes a minimum value Rc(min) of approximately 2000 when BD/D is at a minimum, i.e., at BD/D = 1, Rc(min) = Rc1(max) = Rc2(min) = 2000. Regarding Reynolds's Rc of 12,830, we observed Rc1(max) of approximately 13,000 at BD/D above 1.54. Therefore, the model has been partly verified.

  10. A phase-field theory of dislocation dynamics, strain hardening and hysteresis in ductile single crystals

    NASA Astrophysics Data System (ADS)

    Koslowski, M.; Cuitio, A. M.; Ortiz, M.

    2002-12-01

    A phase-field theory of dislocation dynamics, strain hardening and hysteresis in ductile single crystals is developed. The theory accounts for: an arbitrary number and arrangement of dislocation lines over a slip plane; the long-range elastic interactions between dislocation lines; the core structure of the dislocations resulting from a piecewise quadratic Peierls potential; the interaction between the dislocations and an applied resolved shear stress field; and the irreversible interactions with short-range obstacles and lattice friction, resulting in hardening, path dependency and hysteresis. A chief advantage of the present theory is that it is analytically tractable, in the sense that the complexity of the calculations may be reduced, with the aid of closed form analytical solutions, to the determination of the value of the phase field at point-obstacle sites. In particular, no numerical grid is required in calculations. The phase-field representation enables complex geometrical and topological transitions in the dislocation ensemble, including dislocation loop nucleation, bow-out, pinching, and the formation of Orowan loops. The theory also permits the consideration of obstacles of varying strengths and dislocation line-energy anisotropy. The theory predicts a range of behaviors which are in qualitative agreement with observation, including: hardening and dislocation multiplication in single slip under monotonic loading; the Bauschinger effect under reverse loading; the fading memory effect, whereby reverse yielding gradually eliminates the influence of previous loading; the evolution of the dislocation density under cycling loading, leading to characteristic 'butterfly' curves; and others.

  11. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis.

    PubMed

    Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J; Wang, John; Graetz, Jason

    2015-01-01

    Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3-4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M(1)yM(2)(1-y)F(x): M(1), M(2) = Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid-solution Cu(y)Fe(1-y)F(2), reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu(+) dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries. PMID:25808876

  12. A mixed-percolation model of capillary hysteresis and entrapment in mercury porosimetry

    SciTech Connect

    Ioannidis, M.A.; Chatzis, I. . Dept. of Chemical Engineering)

    1993-12-01

    A wealth of information about the structure of porous materials is contained in the experimental data of mercury intrusion and retraction obtained from mercury porosimetry. Proper interpretation of such data requires the use of a model capable of describing the phenomena of capillary pressure hysteresis and mercury entrapment. This work advances the concept of mixed-percolation on cubic lattices representing pore bodies, connected through pore throats, as a general model for the study of hysteresis and entrapment observed in the course of mercury retraction in porosimetry. The dominant phenomena of local capillary instability (snap-off of mercury threads, piston-type intrusion and retraction), affecting the movement of mercury-air interfaces in pore throats and pore bodies, are accounted for and related to the macroscopic capillary pressure-saturation behavior by means of computer simulation. Local correlations among pore throat and pore body sizes, as well as microscopic heterogeneities due to spatial correlations among the pore bodies are also accounted for in the model. The simulator is used to study the dependence of mercury porosimetry curves on pore throat and pore body size distributions and spatial correlations, as well as on contact angle. It is shown that mercury retraction can be successfully modeled as the deterministic outcome of the competition between two simultaneously occurring percolation processes, snap-off in pore throats (bond-percolation) and piston-type retraction from pore bodies (site-percolation).

  13. Managing managed care: habitus, hysteresis and the end(s) of psychotherapy.

    PubMed

    Kirschner, S R; Lachicotte, W S

    2001-12-01

    In this paper we examine how clinicians at a community mental health center are responding to the beginnings of changes in the health care delivery system, changes that are designated under the rubric of "managed care." We describe how clinicians' attitudes about good mental health care are embodied in what sociologist Pierre Bourdieu calls their habitus, i.e., their professional habits and sense of good practice. Viewed in this light, their moral outrage and sense of threat, as well as their strategic attempts to resist or subvert the dictates of managed care agencies, become a function of what Bourdieu terms the hysteresis effect. The paper is based on ethnographic fieldwork conducted by a team of researchers at the mental health and substance abuse service of a hospital-affiliated, storefront clinic which serves residents of several neighborhoods in a large northeastern city. Data consist primarily of observations of meetings and interviews with staff members. We describe four aspects of the clinicians' professional habitus: a focus on cases as narratives of character and relationship, an imperative of authenticity, a distinctive orientation towards time, and an ethic of ambiguity. We then chronicle practices that have emerged in response to the limits on care imposed by managed care protocols, which are experienced by clinicians as violating the integrity of their work. These are discussed in relation to the concept of hysteresis. PMID:11800075

  14. Motion of an isolated liquid plug inside a capillary tube: effect of contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Srinivasan, Vyas; Khandekar, Sameer; Bouamrane, Nathan; Lefevre, Frederic; Bonjour, Jocelyn

    2015-01-01

    Dynamics of a single, small and isolated partially wetting liquid plug (of known length L and wettability), placed at rest inside a long, dry, circular capillary tube ( D = 1.5 mm), and subsequently quasi-statically pushed from one end by applying air pressure, the other end being kept exposed to atmosphere, are reported. The air pressure first overcomes the `static' friction manifested by the three-phase contact line at the advancing and receding menisci, and then, the plug motion gets initiated, eventually leading to a terminal velocity (Ca ~ 2.8 × 10-5), when pressure force balances net frictional resistance due to viscous and surface forces. It is seen that, under steady motion, the curvature profiles of the advancing and receding menisci of liquid plug, respectively, remain the same, independent of the plug length. Steady-state pressure drop is dominated by the contribution due to contact angle hysteresis, which is also independent of the plug length. Increasing the system wettability drastically decreased the contact angle hysteresis and the associated net pressure drop.

  15. Hysteresis losses and magnetic phenomena in oscillating disks of type II superconductors

    NASA Astrophysics Data System (ADS)

    Cave, J. R.; LeBlanc, M. A. R.

    1982-03-01

    Hysteresis losses and the behavior of the magnetic flux threading superconducting disks of Nb oscillating slowly over various angular displacements in static magnetic fields H0 directed perpendicular to the axis of rotation have been investigated by continuously monitoring and , the average components of the magnetic induction, in the plane of the disk, parallel and perpendicular to H0. A simple model proposed previously satisfactorily accounts for the initial changes, starting from various initial flux configurations, the subsequent cyclical behavior, and the hysteresis losses. Expulsion of flux from the disk occurs during part of the first oscillation, then the amount of flux threading the disk remains constant during the subsequent oscillations, although the orientation distribution of the flux profile undergoes spectacular periodic variations. The analysis shows that d?/dx = k dB/dx describes the orientation of the sheets of flux lines with respect to H0 with distance from the flat surfaces. dB/dx is the critical gradient of flux density and k(T) is the shearing parameter of the flux lattice for the sample. The surface step, ignored in the previous work, is introduced in the model using simple approximations.

  16. Two-phase equilibrium states in individual CuNi nanoparticles: size, depletion and hysteresis effects

    PubMed Central

    2015-01-01

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

  17. A neural approach for the numerical modeling of two-dimensional magnetic hysteresis

    SciTech Connect

    Cardelli, E.; Faba, A.; Laudani, A.; Riganti Fulginei, F.; Salvini, A.

    2015-05-07

    This paper deals with a neural network approach to model magnetic hysteresis at macro-magnetic scale. Such approach to the problem seems promising in order to couple the numerical treatment of magnetic hysteresis to FEM numerical solvers of the Maxwell's equations in time domain, as in case of the non-linear dynamic analysis of electrical machines, and other similar devices, making possible a full computer simulation in a reasonable time. The neural system proposed consists of four inputs representing the magnetic field and the magnetic inductions components at each time step and it is trained by 2-d measurements performed on the magnetic material to be modeled. The magnetic induction B is assumed as entry point and the output of the neural system returns the predicted value of the field H at the same time step. A suitable partitioning of the neural system, described in the paper, makes the computing process rather fast. Validations with experimental tests and simulations for non-symmetric and minor loops are presented.

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

    PubMed

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

    2015-12-23

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

  19. Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

    PubMed Central

    Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Graetz, Jason

    2015-01-01

    Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (34 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2=Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solidsolution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150?mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries. PMID:25808876

  20. Performance analysis of saturated iron core superconducting fault current limiter using Jiles-Atherton hysteresis model

    NASA Astrophysics Data System (ADS)

    Sarkar, D.; Roy, D.; Choudhury, A. B.; Yamada, S.

    2015-09-01

    In this paper study of the Saturated Iron Core Superconducting Fault Current Limiter (SISFCL) has been carried out. Since in an SISFCL, the iron core plays a key role in distributing the magnetic flux, the hysteresis property of the core material has been introduced in a mathematical model to get a more accurate result. In this paper the Jiles-Atherton hysteresis model has been used for modeling the core. The equations are solved through numerical method and performances of SISFCL are analyzed for both normal and fault conditions. On further analysis it is observed that for suppression of higher value of fault current a high voltage develops across the DC source. Hence there is a chance of the DC source being damaged by the rise in voltage under fault condition. In order to protect the DC source, a shorted ring is introduced in the SISFCL circuit and its effects have been analyzed. It is noticed that the shorted ring has successfully reduced the voltage across the DC coil during fault condition while the performance of the limiter remains the same.

  1. 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

  2. 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.

  3. Magnetic hysteresis classification of the lunar surface and the interpretation of permanent remanence in lunar surface samples

    NASA Technical Reports Server (NTRS)

    Wasilewski, P.

    1972-01-01

    A magnetic hysteresis classification of the lunar surface is presented. It was found that there is a distinct correlation between natural remanence (NRM), saturation magnetization, and the hysteresis ratios for the rock samples. The hysteresis classification is able to explain some aspects of time dependent magnetization in the lunar samples and relates the initial susceptibility to NRM, viscous remanence, and to other aspects of magnetization in lunar samples. It is also considered that since up to 60% of the iron in the lunar soil may be super paramagnetic at 400 K, and only 10% at 100 K, the 50% which becomes ferromagnetic over the cycle has the characteristics of thermoremanence and may provide for an enhancement in measurable field on the dark side during a subsatellite magnetometer circuit.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. ST/HR hysteresis: exercise and recovery phase ST depression/heart rate analysis of the exercise ECG.

    PubMed

    Lehtinen, R

    1999-01-01

    ST segment depression/heart rate (ST/HR) hysteresis is a recently introduced novel computer method for integrating the exercise and recovery phase ST/HR analysis for improved detection of coronary artery disease (CAD). It is a continuous diagnostic variable that extracts the prevailing direction and average magnitude of the hysteresis in ST depression against HR during the first 3 consecutive minutes of postexercise recovery. This article reviews the development and evaluation of this new method in a clinical population of 347 patients referred for a routine bicycle exercise electrocardiographic (ECG) test at Tampere University Hospital, Finland. Of these patients, 127 had angiographically proven CAD, whereas 13 had no CAD according to angiography, 18 had no perfusion defect according to Tc-99m-sestamibi myocardial imaging and single photon emission computed tomography, and 189 were clinically normal with respect to cardiac diseases. For each patient, the values for ST/HR hysteresis, ST/HR index, end-exercise ST depression, and recovery ST depression were determined for each lead of the Mason-Likar modification of the standard 12-lead exercise ECG and maximum value from the lead system (aVL, aVR, and V1 excluded). The area under the receiver operating characteristics curve (ie, the discriminative capacity) of the ST/HR hysteresis was 89%, which was significantly larger than that of the end-exercise ST depression (76%, P < .0001), recovery ST depression (84%, P = .0063) or ST/HR index (83%, P = .0023), indicating the best diagnostic performance of the ST/HR hysteresis in detection of CAD regardless of the partition value selection. Furthermore, the superior diagnostic performance of the method was relatively insensitive to the ST segment measurement point or to the ECG lead selection. These results suggest that the ST/HR hysteresis improves the clinical utility of the exercise ECG test in detection of CAD. PMID:10688326

  6. Lattice Boltzmann modeling of contact angle and its hysteresis in two-phase flow with large viscosity difference.

    PubMed

    Liu, Haihu; Ju, Yaping; Wang, Ningning; Xi, Guang; Zhang, Yonghao

    2015-09-01

    Contact angle hysteresis is an important physical phenomenon omnipresent in nature and various industrial processes, but its effects are not considered in many existing multiphase flow simulations due to modeling complexity. In this work, a multiphase lattice Boltzmann method (LBM) is developed to simulate the contact-line dynamics with consideration of the contact angle hysteresis for a broad range of kinematic viscosity ratios. In this method, the immiscible two-phase flow is described by a color-fluid model, in which the multiple-relaxation-time collision operator is adopted to increase numerical stability and suppress unphysical spurious currents at the contact line. The contact angle hysteresis is introduced using the strategy proposed by Ding and Spelt [Ding and Spelt, J. Fluid Mech. 599, 341 (2008)JFLSA70022-112010.1017/S0022112008000190], and the geometrical wetting boundary condition is enforced to obtain the desired contact angle. This method is first validated by simulations of static contact angle and dynamic capillary intrusion process on ideal (smooth) surfaces. It is then used to simulate the dynamic behavior of a droplet on a nonideal (inhomogeneous) surface subject to a simple shear flow. When the droplet remains pinned on the surface due to hysteresis, the steady interface shapes of the droplet quantitatively agree well with the previous numerical results. Four typical motion modes of contact points, as observed in a recent study, are qualitatively reproduced with varying advancing and receding contact angles. The viscosity ratio is found to have a notable impact on the droplet deformation, breakup, and hysteresis behavior. Finally, this method is extended to simulate the droplet breakup in a microfluidic T junction, with one half of the wall surface ideal and the other half nonideal. Due to the contact angle hysteresis, the droplet asymmetrically breaks up into two daughter droplets with the smaller one in the nonideal branch channel, and the behavior of daughter droplets is significantly different in both branch channels. Also, it is found that the contact angle hysteresis is strengthened with decreasing the viscosity ratio, leading to an earlier droplet breakup and a decrease in the maximum length that the droplet can reach before the breakup. These simulation results manifest that the present multiphase LBM can be a useful substitute to Ba etal. [Phys. Rev. E 88, 043306 (2013)PLEEE81539-375510.1103/PhysRevE.88.043306] for modeling the contact angle hysteresis, and it can be easily implemented with higher computational efficiency. PMID:26465585

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

    SciTech Connect

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

    1995-11-01

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

  8. Lattice Boltzmann modeling of contact angle and its hysteresis in two-phase flow with large viscosity difference

    NASA Astrophysics Data System (ADS)

    Liu, Haihu; Ju, Yaping; Wang, Ningning; Xi, Guang; Zhang, Yonghao

    2015-09-01

    Contact angle hysteresis is an important physical phenomenon omnipresent in nature and various industrial processes, but its effects are not considered in many existing multiphase flow simulations due to modeling complexity. In this work, a multiphase lattice Boltzmann method (LBM) is developed to simulate the contact-line dynamics with consideration of the contact angle hysteresis for a broad range of kinematic viscosity ratios. In this method, the immiscible two-phase flow is described by a color-fluid model, in which the multiple-relaxation-time collision operator is adopted to increase numerical stability and suppress unphysical spurious currents at the contact line. The contact angle hysteresis is introduced using the strategy proposed by Ding and Spelt [Ding and Spelt, J. Fluid Mech. 599, 341 (2008), 10.1017/S0022112008000190], and the geometrical wetting boundary condition is enforced to obtain the desired contact angle. This method is first validated by simulations of static contact angle and dynamic capillary intrusion process on ideal (smooth) surfaces. It is then used to simulate the dynamic behavior of a droplet on a nonideal (inhomogeneous) surface subject to a simple shear flow. When the droplet remains pinned on the surface due to hysteresis, the steady interface shapes of the droplet quantitatively agree well with the previous numerical results. Four typical motion modes of contact points, as observed in a recent study, are qualitatively reproduced with varying advancing and receding contact angles. The viscosity ratio is found to have a notable impact on the droplet deformation, breakup, and hysteresis behavior. Finally, this method is extended to simulate the droplet breakup in a microfluidic T junction, with one half of the wall surface ideal and the other half nonideal. Due to the contact angle hysteresis, the droplet asymmetrically breaks up into two daughter droplets with the smaller one in the nonideal branch channel, and the behavior of daughter droplets is significantly different in both branch channels. Also, it is found that the contact angle hysteresis is strengthened with decreasing the viscosity ratio, leading to an earlier droplet breakup and a decrease in the maximum length that the droplet can reach before the breakup. These simulation results manifest that the present multiphase LBM can be a useful substitute to Ba et al. [Phys. Rev. E 88, 043306 (2013), 10.1103/PhysRevE.88.043306] for modeling the contact angle hysteresis, and it can be easily implemented with higher computational efficiency.

  9. Effect of the exchange bias on the magnetization hysteresis of a ferromagnetic film in contact with an antiferromagnet

    NASA Astrophysics Data System (ADS)

    Grechnev, A. G.; Kovalev, A. S.; Pankratova, M. L.

    2013-12-01

    The transformation of the hysteretic field dependence of the magnetization of a ferromagnetic thin layer in contact with a magnetically hard antiferromagnet is considered. It is shown that this interaction leads to a shift of the hysteresis loop from the configuration symmetric with respect to magnetic field (exchange bias). Furthermore, upon increasing the magnitude of the exchange interaction, within a narrow range of the magnitudes, there occurs a qualitative change in the hysteresis loop shape and its subsequent disappearance; hence the field dependence of the magnetization becomes monotonous and single-valued.

  10. The Dynamics and Hysteresis in GaAs/AlGaAs Heterostructure Under the Action of Electric and Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Yang, Gui; Zhao, Hong-Wei; Li, Guo-Hui; Zhou, Shi-Ping

    We theoretically studied current oscillations and the dynamics of the modulation-doped GaAs/AlGaAs heterostructure under the action of electric fields and a perpendicular magnetic field. The results show that the current oscillations and hysteresis in the system can be found under the DC bias voltage. Under the effect of the increasing magnetic fields, the oscillations will disappear and the width of the hysteresis is broader. Considering the AC part, the system shows interesting nonlinear behaviors like the route of an inverse period-doubling to chaos, quasiperiodicity, and frequency-locking.

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

    DOE PAGESBeta

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

    2014-12-31

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

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

    SciTech Connect

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

    2014-12-31

    During CO2 injection and storage in deep reservoirs, the injected CO2 enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO2, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO2, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role for the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm5.6cm61cm), packed with homogeneous and heterogeneous sands. Initial results show that the model can predict spatial and temporal distribution of injected fluid during the experiments reasonably well. However, further analyses are needed for comprehensively testing the ability of the model to predict transient two-phase flow processes and capillary entrapment in geological reservoirs during geological carbon sequestration.

  13. Transitional hysteresis loop and coexistence of synchronized shedding in coupled wakes

    NASA Astrophysics Data System (ADS)

    Peng, Yih Ferng; Sau, Amalendu

    2015-07-01

    Hysteretic in-phase ? anti-phase exchange of vortex shedding and co-existence of reverse-synchronized bistable wake structures past two side-by-side elliptic/circular cylinders are examined through extensive numerical simulations and bifurcation analysis. Wake characteristics and synchronizations past two side-by-side cylinders have often been demarcated in terms of the gap-ratio "G" and the Reynolds number "Re." The focus here is the "in-phase ? anti-phase" two-way transition of oppositely synchronized bistable shedding states. In a remarkable parallel to discontinuous shifts of Strouhal frequency (prompting growth of two distinct instability modes past a single cylinder), the present work reveals interesting in-phase ?anti-phase transitional switching of vortex shedding past two side-by-side symmetric cylinders, as facilitated by "discontinuous jumps of combined lift-force CL,1+2," and preceding bistable wake evolution via both of these two reverse-synchronized phases. The hysteresis loops are demarcated (for cylinders of different aspect-ratios A) through extended computations of two anti-synchronized solution branches by slowly increasing/decreasing the Re at fixed gap-ratio (G) and increasing/decreasing G minutely at a constant Re, thereby facilitating transitions and using the computed discontinuous jumps of CL,1+2. Simulations conducted with various A (0.5 ? A ? 2.0) exhibit, both in-phase and anti-phase shedding co-exist over significantly wide ranges of G-space/Re-space, and the exchange of vortex synchronization at the ends of hysteresis loop occurs through discontinuous variation of the CL,1+2. The "gap-biased" anti-phase ? in-phase transition gets gradually delayed, as the cylinder aspect-ratio A is decreased. However, the "Re-biased" in-phase ? anti-phase transition is advanced with the decrease of A. The tolerance width "HW" of gap-biased hysteresis loop increases fairly linearly, as A decreased over the range 1.0 ? A ? 2.0.

  14. Origin of modulated phases and magnetic hysteresis in TmB4

    SciTech Connect

    Wierschem, Keola; Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Panagopoulos, Christos; Sengupta, Pinaki

    2015-12-23

    In this study, we investigate the low-temperature magnetic phases in TmB4, a metallic quantum magnet on the geometrically frustrated Shastry-Sutherland lattice, using coordinated experimental and theoretical studies. Our results provide an explanation for the appearance of the intriguing fractional plateau in TmB4 and accompanying magnetic hysteresis. Together with observation of the bump in the half plateau, our results support the picture that the magnetization plateau structure in TmB4 is strongly influenced by the zero-field modulated phases. We present a phenomenological model to explain the appearance of the modulated phases and a microscopic Hamiltonian that captures the complete magnetic behavior of TmB4.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  16. 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

  17. Defect-induced asymmetry of local hysteresis loops on BiFeO3 surfaces

    SciTech Connect

    Maksymovych, Petro; Balke, Nina; Jesse, Stephen; Huijben, Mark; Ramesh, R.; Baddorf, Arthur P; Kalinin, Sergei V

    2009-01-01

    Local piezoresponse hysteresis loops were systematically studied on the surface of ferroelectric thin films of BiFeO{sub 3} grown on SrRuO{sub 3} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3} electrodes and compared between ultrahigh vacuum and ambient environment. The loops on all the samples exhibited characteristic asymmetry manifested in the difference of the piezoresponse slope following local domain nucleation. Spatially resolved mapping has revealed that the asymmetry is strongly correlated with the random-field disorder inherent in the films and is not affected by the random-bond disorder component. The asymmetry thus originates from electrostatic disorder within the film, which allows using it as a unique signature of single defects or defect clusters. The electrostatic effects due to the measurement environment also contribute to the total asymmetry of the piezoresponse loop, albeit with a much smaller magnitude compared to local defects.

  18. The fatigue resistance and hysteresis of man-made fibre ropes

    SciTech Connect

    Parsey, M.R.

    1983-09-01

    Data on the fatigue life of man-made fibre ropes is updated and the various mechanisms of rope fatigue discussed. One of these mechanisms, internal hysteresis heating, is examined a little further. Such internal heating should be unimportant in cycling polyester and nylon ropes at non-resonant periods over 24 seconds and at loads of up to 50% of break. But internal temperatures sufficient to cause internal degradation in initially wet size 24 ropes cycled to 28% of break for 24 hours at wave period are predicted from simple theory which agrees well with existing data on smaller ropes. Operators working in such extreme conditions should bear this in mind in defining hawser construction and material.

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

    NASA Astrophysics Data System (ADS)

    Ziebert, Falko; Mohrbach, Herv; 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.

  20. Improving Atomic Force Microscopy Imaging by a Direct Inverse Asymmetric PI Hysteresis Model

    PubMed Central

    Wang, Dong; Yu, Peng; Wang, Feifei; Chan, Ho-Yin; Zhou, Lei; Dong, Zaili; Liu, Lianqing; Li, Wen Jung

    2015-01-01

    A modified Prandtl–Ishlinskii (PI) model, referred to as a direct inverse asymmetric PI (DIAPI) model in this paper, was implemented to reduce the displacement error between a predicted model and the actual trajectory of a piezoelectric actuator which is commonly found in AFM systems. Due to the nonlinearity of the piezoelectric actuator, the standard symmetric PI model cannot precisely describe the asymmetric motion of the actuator. In order to improve the accuracy of AFM scans, two series of slope parameters were introduced in the PI model to describe both the voltage-increase-loop (trace) and voltage-decrease-loop (retrace). A feedforward controller based on the DIAPI model was implemented to compensate hysteresis. Performance of the DIAPI model and the feedforward controller were validated by scanning micro-lenses and standard silicon grating using a custom-built AFM. PMID:25654719

  1. 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.

  2. Hysteresis and Domain Behaviors Analysis of High Purity Fe-(5, 6) wt% Si Alloys

    NASA Astrophysics Data System (ADS)

    Lei, Zhe; Horiuchi, Takuro; Sasaki, Iwao; Kaido, Chikara; Yochi, Horibe; Hata, Satoshi; Ogawa, Toshifumi; Era, Hidenori

    We investigated the improvement in magnetic properties of high-purity Fe-(5, 6) wt% Si formed by cold crucible levitation melting. The results showed that Fe-6 wt% Si alloy has a smaller coercivity than Fe-5 wt% Si. The hysteresis loss of both alloys increases linearly and slightly with maximum magnetization, and increases significantly after a certain maximum magnetization. Additionally, demagnetized domain structure and domain wall motion in both samples was studied by means of Lorentz microscopy. The results indicated that the domain wall motion of Fe-6 wt% Si can be activated in lower external fields and displaces more rapidly than Fe-5 wt% Si. Moreover, the displacement of domain walls that penetrate symmetrical grain boundaries and dislocations in Fe-6 wt% Si was analyzed. The boundaries and dislocations have no pinning effect on domain wall motion.

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

    SciTech Connect

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

    1995-08-01

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

  4. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    SciTech Connect

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

    2015-07-01

    The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  5. A Low Hysteresis NiTiFe Shape Memory Alloy Based Thermal Conduction Switch

    SciTech Connect

    Lemanski, J. L.; Krishnan, V. B.; Manjeri, R. Mahadevan; Vaidyanathan, R.; Notardonato, W. U.

    2006-03-31

    Shape memory alloys possess the ability to return to a preset shape by undergoing a solid state phase transformation at a particular temperature. This work reports on the development and testing of a low temperature thermal conduction switch that incorporates a NiTiFe shape memory element for actuation. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the temperature of methane. The shape memory element in the switch undergoes a rhombohedral or R-phase transformation that is associated with a small hysteresis (typically 1-2 deg. C) and offers the advantage of precision control over a set temperature range. For the NiTiFe alloy used, its thermomechanical processing, subsequent characterization using dilatometry, differential scanning calorimetry and implementation in the conduction switch configuration are addressed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The magnetic hysteresis loops and Barkhausen noise of a single ?-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  7. On the hysteresis of the sea surface and its applicability to wave height predictions

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.

    1977-01-01

    Because of the low dissipation rate of wave energy on the ocean's surface, the wave height at some location and time must be dependent upon wind fields in existence there at previous times and upon swell propagated there from other regions. To study these relationships, significant wave height (SWH) measurements from the Geos-3 radar altimeter are used in conjunction with anemometer windspeed measurements from weather ships, L, C, and R. During the passage of large cyclonic disturbances near the fixed locations of these vessels in the North Atlantic in February 1976, distinct hysteresis profiles that characterize the sea's memory during generation and dissipation conditions are observed. Examples are given that demonstrate the influences of cyclone intensity, movement, velocity, and shape on the configuration of these profiles.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  9. Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities

    DOEpatents

    Humphrey, Floyd B.

    1987-01-01

    A marker for an electronic article surveillance system is disclosed comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that, upon exposure of the marker to an external magnetic field whose field strength in the direction opposing the instantaneous magnetic polarization of the marker exceeds a predetermined threshold value, there results a regenerative reversal of the magnetic polarization of the marker. An electronic article surveillance system and a method utilizing the marker are also disclosed. Exciting the marker with a low frequency and low field strength, so long as the field strength exceeds the low threshold level for the marker, causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.

  10. Origin of modulated phases and magnetic hysteresis in TmB4

    DOE PAGESBeta

    Wierschem, Keola; Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Panagopoulos, Christos; Sengupta, Pinaki

    2015-12-23

    In this study, we investigate the low-temperature magnetic phases in TmB4, a metallic quantum magnet on the geometrically frustrated Shastry-Sutherland lattice, using coordinated experimental and theoretical studies. Our results provide an explanation for the appearance of the intriguing fractional plateau in TmB4 and accompanying magnetic hysteresis. Together with observation of the bump in the half plateau, our results support the picture that the magnetization plateau structure in TmB4 is strongly influenced by the zero-field modulated phases. We present a phenomenological model to explain the appearance of the modulated phases and a microscopic Hamiltonian that captures the complete magnetic behavior ofmore » TmB4.« less

  11. 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

  12. Parameter estimation of the Bouc Wen hysteresis model using particle swarm optimization

    NASA Astrophysics Data System (ADS)

    Ye, Meiying; Wang, Xiaodong

    2007-12-01

    Particle swarm optimization (PSO), which is a new robust stochastic evolutionary computational algorithm based on the movement and intelligence of swarms, is proposed to estimate parameters of the Bouc-Wen hysteresis model. The performance of the PSO method is compared with the more common genetic algorithms (GAs) in terms of parameter accuracy. Simulation results of the Bouc-Wen model with all the unknown parameters are illustrated to show that a higher quality solution with better computational efficiency than the GA method can be achieved by means of the PSO method. Furthermore, parameter estimation of the Bouc-Wen model with noisy data is considered. The results show that the proposed method is still effective even if the simulated data are corrupted by noise.

  13. Angular dependence of hysteresis scaling and coercivity for anisotropically distributed ferromagnetic nanoparticles in paramagnetic matrix

    NASA Astrophysics Data System (ADS)

    Miura, Kodai; Kobayashi, Satoru; Onuki, Yusuke; Szpunar, Jerzy A.; Kamada, Yasuhiro

    2015-05-01

    We have investigated anisotropy behavior of coercivity and scaling law for nano-scale ferromagnetic phases embedded in a paramagnetic matrix of an austenitic stainless steel. Small ferromagnetic martensites are induced by uniaxial tensile deformation. A scaling-law relationship between the hysteresis loss and remanence, with a power law exponent of 1.47 0.09, has been found, irrespective of stress, martensite volume fraction, and angle between the magnetization and tensile directions. A coefficient of the scaling law decreases with volume fraction, whereas it increases with increasing the angle and maximizes when the magnetization direction is perpendicular to that of the tensile. This trend is opposite to that of coercivity. The behavior of the coefficient and the coercivity was discussed from the viewpoint of morphology of martensite particles.

  14. 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.

  15. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    DOE PAGESBeta

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

    2015-07-01

    The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domainsmore » on the magnetization reversal behavior and the magnetic properties.« less

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  17. 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

  18. Ion current rectification in funnel-shaped nanochannels: Hysteresis and inversion effects

    NASA Astrophysics Data System (ADS)

    Rosentsvit, Leon; Wang, Wei; Schiffbauer, Jarrod; Chang, Hsueh-Chia; Yossifon, Gilad

    2015-12-01

    Ion current rectification inversion is observed in a funnel-shaped nanochannel above a threshold voltage roughly corresponding to the under-limiting to over-limiting current transition. Previous experimental studies have examined rectification at either low-voltages (under-limiting current region) for conical nanopores/funnel-shaped nanochannels or at high-voltages (over-limiting region) for straight nanochannels with asymmetric entrances or asymmetric interfacing microchannels. The observed rectification inversion occurs because the system resistance is shifted, beyond a threshold voltage, from being controlled by intra-channel ion concentration-polarization to that controlled by external concentration-polarization. Additionally, strong hysteresis effects, due to residual concentration-polarization, manifest themselves through the dependence of the transient current rectification on voltage scan rate.

  19. Ion current rectification in funnel-shaped nanochannels: Hysteresis and inversion effects.

    PubMed

    Rosentsvit, Leon; Wang, Wei; Schiffbauer, Jarrod; Chang, Hsueh-Chia; Yossifon, Gilad

    2015-12-14

    Ion current rectification inversion is observed in a funnel-shaped nanochannel above a threshold voltage roughly corresponding to the under-limiting to over-limiting current transition. Previous experimental studies have examined rectification at either low-voltages (under-limiting current region) for conical nanopores/funnel-shaped nanochannels or at high-voltages (over-limiting region) for straight nanochannels with asymmetric entrances or asymmetric interfacing microchannels. The observed rectification inversion occurs because the system resistance is shifted, beyond a threshold voltage, from being controlled by intra-channel ion concentration-polarization to that controlled by external concentration-polarization. Additionally, strong hysteresis effects, due to residual concentration-polarization, manifest themselves through the dependence of the transient current rectification on voltage scan rate. PMID:26671395

  20. Origin of modulated phases and magnetic hysteresis in TmB4

    NASA Astrophysics Data System (ADS)

    Wierschem, Keola; Sunku, Sai Swaroop; Kong, Tai; Ito, Toshimitsu; Canfield, Paul C.; Panagopoulos, Christos; Sengupta, Pinaki

    2015-12-01

    We investigate the low-temperature magnetic phases in TmB4 , a metallic quantum magnet on the geometrically frustrated Shastry-Sutherland lattice, using coordinated experimental and theoretical studies. Our results provide an explanation for the appearance of the intriguing fractional plateau in TmB4 and accompanying magnetic hysteresis. Together with observation of the bump in the half plateau, our results support the picture that the magnetization plateau structure in TmB4 is strongly influenced by the zero-field modulated phases. We present a phenomenological model to explain the appearance of the modulated phases and a microscopic Hamiltonian that captures the complete magnetic behavior of TmB4 .

  1. A two-step route to planar perovskite cells exhibiting reduced hysteresis

    SciTech Connect

    Ip, Alexander H.; Adachi, Michael M.; McDowell, Jeffrey J.; Xu, Jixian; Sargent, Edward H.; Quan, Li Na; Kim, Dong Ha

    2015-04-06

    A simple two-step method was used to produce efficient planar organolead halide perovskite solar cells. Films produced using solely iodine containing precursors resulted in poor morphology and failed devices, whereas addition of chlorine to the process greatly improved morphology and resulted in dense, uniform perovskite films. This process was used to produce perovskite solar cells with a fullerene-based passivation layer. The hysteresis effect, to which planar perovskite devices are otherwise prone, was greatly suppressed through the use of this interface modifier. The combined techniques resulted in perovskite solar cells having a stable efficiency exceeding 11%. This straightforward fabrication procedure holds promise in development of various optoelectronic applications of planar perovskite films.

  2. 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

  3. Manipulation of transport hysteresis on graphene field effect transistors with Ga ion irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Quan; Liu, Shuai; Ren, Naifei

    2014-09-01

    We have studied the effect of Ga ion irradiation on the controllable hysteretic behavior of graphene field effect transistors fabricated on Si/SO2 substrates. The various densities of defects in graphene were monitored by Raman spectrum. It was found that the Dirac point shifted to the positive gate voltage constantly, while the hysteretic behavior was enhanced first and then weakened, with the dose of ion irradiation increasing. By contrasting the trap charges density induced by dopant and the total density of effective trap charges, it demonstrated that adsorbate doping was not the decisive factor that induced the hysteretic behavior. The tunneling between the defect sites induced by ion irradiation was also an important cause for the hysteresis.

  4. Unified model of hyperthermia via hysteresis heating in systems of interacting magnetic nanoparticles.

    PubMed

    Ruta, S; Chantrell, R; Hovorka, O

    2015-01-01

    We present a general study of the frequency and magnetic field dependence of the specific heat power produced during field-driven hysteresis cycles in magnetic nanoparticles with relevance to hyperthermia applications in biomedicine. Employing a kinetic Monte-Carlo method with natural time scales allows us to go beyond the assumptions of small driving field amplitudes and negligible inter-particle interactions, which are fundamental to the applicability of the standard approach based on linear response theory. The method captures the superparamagnetic and fully hysteretic regimes and the transition between them. Our results reveal unexpected dipolar interaction-induced enhancement or suppression of the specific heat power, dependent on the intrinsic statistical properties of particles, which cannot be accounted for by the standard theory. Although the actual heating power is difficult to predict because of the effects of interactions, optimum heating is in the transition region between the superparamagnetic and fully hysteretic regimes. PMID:25766365

  5. Hysteresis and drift of spiral waves near heterogeneities: From chemical experiments to cardiac simulations

    NASA Astrophysics Data System (ADS)

    Nakouzi, Elias; Totz, Jan Frederik; Zhang, Zhihui; Steinbock, Oliver; Engel, Harald

    2016-02-01

    Dissipative patterns in excitable reaction-diffusion systems can be strongly affected by spatial heterogeneities. Using the photosensitive Belousov-Zhabotinsky reaction, we show a hysteresis effect in the transition between free and pinned spiral rotation. The latter state involves the rotation around a disk-shaped obstacle with an impermeable and inert boundary. The transition is controlled by changes in light intensity. For permeable heterogeneities of higher excitability, we observe spiral drift along both linear and circular boundaries. Our results confirm recent theoretical predictions and, in the case of spiral drift, are further reproduced by numerical simulations with a modified Oregonator model. Additional simulations with a cardiac model show that orbital motion can also exist in anisotropic and three-dimensional systems.

  6. Nonlinear ac stationary response and dynamic magnetic hysteresis of quantum uniaxial superparamagnets

    NASA Astrophysics Data System (ADS)

    Kalmykov, Yuri P.; Titov, Serguey V.; Coffey, William T.

    2015-11-01

    The nonlinear ac stationary response of uniaxial paramagnets and superparamagnets—nanoscale solids or clusters with spin number S ˜100-104 —in superimposed uniform ac and dc bias magnetic fields of arbitrary strength, each applied along the easy axis of magnetization, is determined by solving the evolution equation for the reduced density matrix represented as a finite set of three-term differential-recurrence relations for its diagonal matrix elements. The various harmonic components arising from the nonlinear response of the magnetization, dynamic magnetic hysteresis loops, etc., are then evaluated via matrix continued fractions indicating a pronounced dependence of the response on S arising from the quantum spin dynamics, which differ markedly from the magnetization dynamics of classical nanomagnets. In the linear response approximation, the results concur with existing solutions.

  7. Improving atomic force microscopy imaging by a direct inverse asymmetric PI hysteresis model.

    PubMed

    Wang, Dong; Yu, Peng; Wang, Feifei; Chan, Ho-Yin; Zhou, Lei; Dong, Zaili; Liu, Lianqing; Li, Wen Jung

    2015-01-01

    A modified Prandtl-Ishlinskii (PI) model, referred to as a direct inverse asymmetric PI (DIAPI) model in this paper, was implemented to reduce the displacement error between a predicted model and the actual trajectory of a piezoelectric actuator which is commonly found in AFM systems. Due to the nonlinearity of the piezoelectric actuator, the standard symmetric PI model cannot precisely describe the asymmetric motion of the actuator. In order to improve the accuracy of AFM scans, two series of slope parameters were introduced in the PI model to describe both the voltage-increase-loop (trace) and voltage-decrease-loop (retrace). A feedforward controller based on the DIAPI model was implemented to compensate hysteresis. Performance of the DIAPI model and the feedforward controller were validated by scanning micro-lenses and standard silicon grating using a custom-built AFM. PMID:25654719

  8. 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

  9. Hysteresis processes in the regular reflection?Mach reflection transition in steady flows

    NASA Astrophysics Data System (ADS)

    Ben-Dor, G.; Ivanov, M.; Vasilev, E. I.; Elperin, T.

    2002-05-01

    Ernst Mach recorded experimentally, in the late 1870s, two different shock-wave reflection configurations and laid the foundations for one of the most exciting and active research field in an area that is generally known as Shock Wave Reflection Phenomena. The first wave reflection, a two-shock wave configuration, is known nowadays as regular reflection, RR, and the second wave reflection, a three-shock wave configuration, was named after Ernst Mach and is called nowadays Mach reflection, MR. A monograph entitled Shock Wave Reflection Phenomena, which was published by Ben-Dor in 1990, summarized the state-of-the-art of the reflection phenomena of shock waves in steady, pseudo-steady and unsteady flows. Intensive analytical, experimental and numerical investigations in the last decade, which were led mainly by Ben-Dor's research group and his collaboration with Chpoun's, Zeitoun's and Ivanov's research groups, shattered the state-of-the-knowledge, as it was presented in Ben-Dor (Shock Wave Reflection Phenomena, Springer, New York, 1991), for the case of steady flows. Skews's and Hornung's research groups joined in later and also contributed to the establishment of the new state-of-the-knowledge of the reflection of shock waves in steady flows. The new state-of-the-knowledge will be presented in this review. Specifically, the hysteresis phenomenon in the RR?MR transition process, which until the early 1990s was believed not to exist, will be presented and described in detail, in a variety of experimental set-ups and geometries. Analytical, experimental and numerical investigations of the various hysteresis processes will be presented.

  10. Hydrostatic pressure effect on magnetic hysteresis parameters of multidomain magnetite: Implication for crustal magnetization

    NASA Astrophysics Data System (ADS)

    Sato, Masahiko; Yamamoto, Yuhji; Nishioka, Takashi; Kodama, Kazuto; Mochizuki, Nobutatsu; Tsunakawa, Hideo

    2014-08-01

    Hydrostatic pressure effects on magnetic parameters for crustal rock have been poorly investigated yet, while it is important for an understanding of source of long-wavelength magnetic anomaly, which is considered to reside in deep crust. In this study we have conducted the in situ magnetic hysteresis measurements on multidomain (MD) magnetite under high pressure up to 1 GPa. With special attention to hydrostatic condition and sample preparation, pressure dependences of its magnetic hysteresis parameters (saturation magnetization, Ms; saturation remanence, Mrs; coercivity, Bc; coercivity of remanence, Bcr) are revealed as follows: (1) Bc monotonically increases with pressure at a rate of +91%/GPa; (2) Ms is constant under high pressure up to 1 GPa; (3) Mrs increases with pressure up to 0.5 GPa by ∼30% and reaches to saturation above the pressure; (4) Bcr is nearly constant at low pressure, and it increases above ∼0.6 GPa; and (5) the changes in ratios Mrs/Ms and Bcr/Bc correlate with each other, resulting in systematic movement on the Day plot. These findings allow us to estimate change in a relaxation time of magnetic remanence carried by MD magnetite as a function of depth in the continental crust. In the model calculation, we consider no effect of plastic deformation on magnetic properties of magnetite, and the relaxation time is calculated using the theoretical thermal gradient. In consequence, the relaxation time monotonously decreases with depth, and primary remanence is considered to be replaced by a viscous remanent magnetization (VRM) over the Brunhes chron. Therefore, it is suggested that MD magnetite in deep crustal rocks can contribute to the source of the anomaly over the continental crust by VRM and induced magnetization.

  11. Hydrological hysteresis and its value for assessing process consistency in catchment conceptual models

    NASA Astrophysics Data System (ADS)

    Fovet, O.; Ruiz, L.; Hrachowitz, M.; Faucheux, M.; Gascuel-Odoux, C.

    2015-01-01

    While most hydrological models reproduce the general flow dynamics, they frequently fail to adequately mimic system-internal processes. In particular, the relationship between storage and discharge, which often follows annual hysteretic patterns in shallow hard-rock aquifers, is rarely considered in modelling studies. One main reason is that catchment storage is difficult to measure, and another one is that objective functions are usually based on individual variables time series (e.g. the discharge). This reduces the ability of classical procedures to assess the relevance of the conceptual hypotheses associated with models. We analysed the annual hysteric patterns observed between stream flow and water storage both in the saturated and unsaturated zones of the hillslope and the riparian zone of a headwater catchment in French Brittany (Environmental Research Observatory ERO AgrHys (ORE AgrHys)). The saturated-zone storage was estimated using distributed shallow groundwater levels and the unsaturated-zone storage using several moisture profiles. All hysteretic loops were characterized by a hysteresis index. Four conceptual models, previously calibrated and evaluated for the same catchment, were assessed with respect to their ability to reproduce the hysteretic patterns. The observed relationship between stream flow and saturated, and unsaturated storages led us to identify four hydrological periods and emphasized a clearly distinct behaviour between riparian and hillslope groundwaters. Although all the tested models were able to produce an annual hysteresis loop between discharge and both saturated and unsaturated storage, the integration of a riparian component led to overall improved hysteretic signatures, even if some misrepresentation remained. Such a system-like approach is likely to improve model selection.

  12. Low drift and small hysteresis characteristics of diamond electrolyte-solution-gate FET

    NASA Astrophysics Data System (ADS)

    Sasaki, Yoshinori; Kawarada, Hiroshi

    2010-09-01

    We have investigated drift and hysteresis characteristics on an electrolyte-solution-gate field-effect transistor (SGFET) with a unique structure using polycrystalline diamond and verified the possibility as chemical sensors and biosensors. Silicon-based ion-sensitive field effect transistors (ISFETs) have not yet solved such time-related issues due to the chemical instability of the passivation layer covering on SiO2 and that is why the Si-ISFET is not wide spread. First of all, we have confirmed that the pH sensitivities of oxygen- and amine-terminated diamond surfaces are 20 mV/pH and 48 mV/pH, respectively, whereas that of hydrogen-terminated surface is only 7 mV/pH. Drift characteristics measurement on diamond SGFET reveals that diamond SGFETs with any surface termination are more stable in electrolyte solution than Si-ISFETs with typical passivation membranes. Hysteresis width, which is known to be a more serious cause of measurement error than drift, proves to be 0.39 mV on amine-terminated SGFET. This is less than 1/10 compared with common Si3N4-ISFET. These results can be explained by high tolerance of diamond against ions in solution due to intrinsic chemical stability and densely packed structure of diamond itself. In this work, we bear out that diamond SGFET is a promising platform for highly sensitive biosensor application owing to the superiority in terms of time response and resulting measurement accuracy.

  13. 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 65N 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.

  14. Minimization of the hysteresis loss and low-field instability in technical Nb3Al conductors

    NASA Astrophysics Data System (ADS)

    Banno, N.; Takeuchi, T.; Nimori, S.; Tanaka, K.; Nakagawa, K.; Tsuchiya, K.

    2008-11-01

    This paper focuses on the magnetization characteristics of technical Nb3Al conductors, in particular the minimization of their hysteresis loss and low-field instability. Unlike the case of Nb3Sn wire fabrication, the Nb3Al wire is fabricated by a phase transformation process, in which it is believed that the Jc properties of the transformed Nb3Al phase do not depend on the filament size or shape, but rather are principally controlled by the rapid heating and quenching or transformation conditions. However, the rapid heating and quenching process forces us to use high-melting-point metals like niobium as the matrix. The use of Nb strongly affects the magnetization because of its superconductivity in low fields. In this paper, the magnetization properties of several kinds of technical Nb3Al conductors, including Ta matrix wires, were studied. The use of Ta was effective in suppressing low-field instability. In addition, we propose a new process to further minimize the filament diameter by a re-stacking (RS) method, whereby the rapidly quenched strands are re-stacked into a stabilizing material tube and co-drawn. This process leads to a very fine multifilamentary structure with a filament diameter of less than 15 m, thereby substantially reducing the magnetization, as compared with high-performance Nb3Sn wires, e.g. RRP Nb3Sn wire. The 3 T hysteresis loss of the RS Nb3Al conductor was 370 mJ cm-3 and the non-Cu Jc (12 T, 4.2 K) of the conductor was 1350 A mm-2. These values meet the ITER strand specification.

  15. Numerical simulation of dune-flat bed transition and stage-discharge relationship with hysteresis effect

    USGS Publications Warehouse

    Shimizu, Y.; Giri, S.; Yamaguchi, S.; Nelson, J.

    2009-01-01

    This work presents recent advances on morphodynamic modeling of bed forms under unsteady discharge. This paper includes further development of a morphodynamic model proposed earlier by Giri and Shimizu (2006a). This model reproduces the temporal development of river dunes and accurately replicates the physical properties associated with bed form evolution. Model results appear to provide accurate predictions of bed form geometry and form drag over bed forms for arbitrary steady flows. However, accurate predictions of temporal changes of form drag are key to the prediction of stage-discharge relation during flood events. Herein, the model capability is extended to replicate the dune-flat bed transition, and in turn, the variation of form drag produced by the temporal growth or decay of bed forms under unsteady flow conditions. Some numerical experiments are performed to analyze hysteresis of the stage-discharge relationship caused by the transition between dune and flat bed regimes during rising and falling stages of varying flows. The numerical model successfully simulates dune-flat bed transition and the associated hysteresis of the stage-discharge relationship; this is in good agreement with physical observations but has been treated in the past only using empirical methods. A hypothetical relationship for a sediment parameter (the mean step length) is proposed to a first level of approximation that enables reproduction of the dune-flat bed transition. The proposed numerical model demonstrates its ability to address an important practical problem associated with bed form evolution and flow resistance in varying flows. Copyright 2009 by the American Geophysical Union.

  16. 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

    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.

  17. 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.

  18. Nonlinear friction modelling and compensation control of hysteresis phenomena for a pair of tendon-sheath actuated surgical robots

    NASA Astrophysics Data System (ADS)

    Do, T. N.; Tjahjowidodo, T.; Lau, M. W. S.; Phee, S. J.

    2015-08-01

    Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a special method that allows surgical operations via natural orifices like mouth, anus, and vagina, without leaving visible scars. The use of flexible tendon-sheath mechanism (TSM) is common in these systems because of its light weight in structure, flexibility, and easy transmission of power. However, nonlinear friction and backlash hysteresis pose many challenges to control of such systems; in addition, they do not provide haptic feedback to assist the surgeon in the operation of the systems. In this paper, we propose a new dynamic friction model and backlash hysteresis nonlinearity for a pair of TSM to deal with these problems. The proposed friction model, unlike current approaches in the literature, is smooth and able to capture the force at near zero velocity when the system is stationary or operates at small motion. This model can be used to estimate the friction force for haptic feedback purpose. To improve the system tracking performances, a backlash hysteresis model will be introduced, which can be used in a feedforward controller scheme. The controller involves a simple computation of the inverse hysteresis model. The proposed models are configuration independent and able to capture the nonlinearities for arbitrary tendon-sheath shapes. A representative experimental setup is used to validate the proposed models and to demonstrate the improvement in position tracking accuracy and the possibility of providing desired force information at the distal end of a pair of TSM slave manipulator for haptic feedback to the surgeons.

  19. Experimental studies of contact angle hysteresis phenomena on polymer surfaces Toward the understanding and control of wettability for different applications.

    PubMed

    Grundke, K; Pschel, K; Synytska, A; Frenzel, R; Drechsler, A; Nitschke, M; Cordeiro, A L; Uhlmann, P; Welzel, P B

    2015-08-01

    Contact angle hysteresis phenomena on polymer surfaces have been studied by contact angle measurements using sessile liquid droplets and captive air bubbles in conjunction with a drop shape method known as Axisymmetric Drop Shape Analysis - Profile (ADSA-P). In addition, commercially available sessile drop goniometer techniques were used. The polymer surfaces were characterized with respect to their surface structure (morphology, roughness, swelling) and surface chemistry (elemental surface composition, acid-base characteristics) by scanning electron microscopy (SEM), scanning force microscopy (SFM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and streaming potential measurements. Heterogeneous polymer surfaces with controlled roughness and chemical composition were prepared by different routes using plasma etching and subsequent dip coating or grafting of polymer brushes, anodic oxidation of aluminium substrates coated with thin polymer films, deposition techniques to create regular patterned and rough fractal surfaces from core-shell particles, and block copolymers. To reveal the effects of swelling and reorientation at the solid/liquid interface contact angle hysteresis phenomena on polyimide surfaces, cellulose membranes, and thermo-responsive hydrogels have been studied. The effect of different solutes in the liquid (electrolytes, surfactants) and their impact on contact angle hysteresis were characterized for solid polymers without and with ionizable functional surface groups in aqueous electrolyte solutions of different ion concentrations and pH and for photoresist surfaces in cationic aqueous surfactant solutions. The work is an attempt toward the understanding of contact angle hysteresis phenomena on polymer surfaces aimed at the control of wettability for different applications. PMID:25488284

  20. Modeling for Fatigue Hysteresis Loops of Carbon Fiber-Reinforced Ceramic-Matrix Composites under Multiple Loading Stress Levels

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    In this paper, the fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) under multiple loading stress levels considering interface wear has been investigated using micromechanical approach. Under fatigue loading, the fiber/matrix interface shear stress decreases with the increase of cycle number due to interface wear. Upon increasing of fatigue peak stress, the interface debonded length would propagate along the fiber/matrix interface. The difference of interface shear stress existed in the new and original debonded region would affect the interface debonding and interface frictional slipping between the fiber and the matrix. Based on the fatigue damage mechanism of fiber slipping relative to matrix in the interface debonded region upon unloading and subsequent reloading, the interface slip lengths, i.e., the interface debonded length, interface counter-slip length and interface new-slip length, are determined by fracture mechanics approach. The fatigue hysteresis loops models under multiple loading stress levels have been developed. The effects of single/multiple loading stress levels and different loading sequences on fatigue hysteresis loops have been investigated. The fatigue hysteresis loops of unidirectional C/SiC composite under multiple loading stress levels have been predicted.

  1. Origins of Large Voltage Hysteresis in High-Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes.

    PubMed

    Li, Linsen; Jacobs, Ryan; Gao, Peng; Gan, Liyang; Wang, Feng; Morgan, Dane; Jin, Song

    2016-03-01

    Metal fluorides and oxides can store multiple lithium ions through conversion chemistry to enable high-energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage profiles and the consequent low-energy efficiency (<80%). The physical origins of such hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy, transmission electron microscopy, density functional theory calculations, and galvanostatic intermittent titration technique to first correlate the voltage profile of iron fluoride (FeF3), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the FeF3 electrode is kinetic in nature. It is the result of ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically active phases (i.e., compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry. PMID:26847657

  2. Detection scheme in a fiber-optic magnetic-field sensor free from ambiguity due to material magnetic hysteresis.

    PubMed

    Koo, K P; Sigel, G H

    1984-06-01

    A new technique has been demonstrated in the detection of low-frequency or dc magnetic fields in an optical-fiber interferometric sensor using the magnetostrictive approach. This technique permits magnetic-field measurements free of ambiguity associated with hysteresis effects of the material. PMID:19721563

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

    SciTech Connect

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

    2015-05-07

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

  4. Purification, composition, and physical properties of a thermal hysteresis "antifreeze" protein from larvae of the beetle, Tenebrio molitor.

    PubMed

    Tomchaney, A P; Morris, J P; Kang, S H; Duman, J G

    1982-02-16

    Proteins which produce a thermal hysteresis (difference between the freezing and melting points) in aqueous solution are well-known for their antifreeze activity in polar marine fishes. Much less is known about the biology and biochemistry of similar antifreeze proteins found in certain insects. A thermal hysteresis protein was purified from cold acclimated larvae of the beetle, Tenebrio molitor, by using ethanol fractionation, DEAE ion-exchange chromatography, gel filtration, and high-pressure liquid chromatography. The purified protein had a molecular mass of 17 000 daltons and its N terminus was lysine. The amino acid composition of the antifreeze protein contained more hydrophilic amino acids than the fish antifreezes. This is consistent with the compositions of previously purified insect thermal hysteresis proteins. However, the percentage of hydrophilic amino acids in this Tenebrio antifreeze protein was considerably less than that of other insect thermal hysteresis proteins. The freezing point depressing activity of the Tenebrio antifreeze was less than that of fish proteins and glycoproteins at low protein concentrations but was greater at high protein concentrations. PMID:7074035

  5. A simple fuzzy system for modelling of both rate-independent and rate-dependent hysteresis in piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Li, Pengzhi; Yan, Feng; Ge, Chuan; Wang, Xueliang; Xu, Lisong; Guo, Jialiang; Li, Peiyue

    2013-03-01

    In this paper, a novel fuzzy system based method for modelling both rate-independent and rate-dependent hysteresis in the piezoelectric actuator is proposed. First, the partial Takagi-Sugeno (T-S) fuzzy rule is designed. The antecedent structure of the fuzzy system is identified through uniform partition of its input variable. Then, the parameters of the consequent structure are optimized via the recursive least squares (RLS) algorithm. The modelling method is simple to implement and highly efficient to compute. Experimental results show that the proposed method is efficient to model both rate-independent and rate-dependent hysteresis. Based on the inverse of the developed model, feed-forward hysteresis compensation experiments at the frequencies of 50 Hz and 100 Hz are also conducted with the hysteresis effects being obviously reduced. The major contribution of this paper is that the inverse of the model can be analytically computed and the method can be applied to the case of real-time on-line modelling.

  6. Unifying soil respiration pulses, inhibition, and temperature hysteresis through dynamics of labile soil carbon and O2

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Grantz, D. A.; Chatterjee, A.; Eberwein, J. E.; Allsman, L. A.; Jenerette, G. D.

    2014-04-01

    Event-driven and diel dynamics of soil respiration (Rs) strongly influence terrestrial carbon (C) emissions and are difficult to predict. Wetting events may cause a large pulse or strong inhibition of Rs. Complex diel dynamics include hysteresis in the relationship between Rs and soil temperature. The mechanistic basis for these dynamics is not well understood, resulting in large discrepancies between predicted and observed Rs. We present a unifying approach for interpreting these phenomena in a hot arid agricultural environment. We performed a whole ecosystem wetting experiment with continuous measurement of Rs to study pulse responses to wetting in a heterotrophic system. We also investigated Rs during cultivation of Sorghum bicolor to evaluate the role of photosynthetic C in the regulation of diel variation in Rs. Finally, we adapted a Rs model with sensitivity to soil O2 and water content by incorporating two soil C pools differing in lability. We observed a large wetting-induced pulse of Rs from the fallow field and were able to accurately simulate the pulse via release of labile soil C. During the exponential phase of plant growth, Rs was inhibited in response to wetting, which was accurately simulated through depletion of soil O2. Without plants, hysteresis was not observed; however, with growing plants, an increasingly significant counterclockwise hysteresis developed. Hysteresis was simulated via a dynamic photosynthetic C pool and was not likely controlled by physical processes. These results help characterize the complex regulation of Rs and improve understanding of these phenomena under warmer and more variable conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Khoury, Charbel N.

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

  9. OP09O-OP404-9 Wide Field Camera 3 CCD Quantum Efficiency Hysteresis

    NASA Technical Reports Server (NTRS)

    Collins, Nick

    2009-01-01

    The HST/Wide Field Camera (WFC) 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. At the nominal operating temperature of -83C, the QEH feature contrast was typically 0.1-0.2% or less. The behavior was replicated using flight spare detectors. A visible light flat-field (540nm) with a several times full-well signal level can pin the detectors at both optical (600nm) and near-UV (230nm) wavelengths, suppressing the QEH behavior. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. The HST/Wide Field Camera 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. The first observed manifestation of QEH was the presence in a small percentage of flat-field images of a bowtie-shaped contrast that spanned the width of each chip. At the nominal operating temperature of -83C, the contrast observed for this feature was typically 0.1-0.2% or less, though at warmer temperatures contrasts up to 5% (at -50C) have been observed. The bowtie morphology was replicated using flight spare detectors in tests at the GSFC Detector Characterization Laboratory by power cycling the detector while cold. Continued investigation revealed that a clearly-related global QE suppression at the approximately 5% level can be produced by cooling the detector in the dark; subsequent flat-field exposures at a constant illumination show asymptotically increasing response. This QE "pinning" can be achieved with a single high signal flat-field or a series of lower signal flats; a visible light (500-580nm) flat-field with a signal level of several hundred thousand electrons per pixel is sufficient for QE pinning at both optical (600nm) and near-UV (230nm) wavelengths. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. A preliminary estimate of the decay timescale for one detector is that a drop of 0.1-0.2% occurs over a ten day period, indicating that relatively infrequent cal lamp exposures can mitigate the behavior to extremely low levels.

  10. Diffuse and constricted modes of a dc discharge in neon: Simulation of the hysteresis transition

    SciTech Connect

    Shkurenkov, I. A.; Mankelevich, Yu. A.; Rakhimova, T. V.

    2008-09-15

    Results are presented from theoretical studies of high-pressure ({approx}100 Torr) dc discharges in neon. The diffuse and constricted discharge modes are studied using a model including the equation of balance for charged and excited particles, heat conduction equations for the neutral gas and plasma electrons, and Poisson's equation for the radial electric field at a fixed total discharge current. A specific feature of the constricted mode in the investigated range of low fields and high degrees of ionization is that the excitation and ionization rates in the center of the discharge tube and at the periphery differ by several orders of magnitude. This implies that, in the constricted mode, the region where the electron energy distribution function is Maxwellian due to electron-electron collisions may adjoin the region (beyond the constriction zone) where the high-energy part of the distribution function is depleted. The hysteresis transition between the diffuse and constricted modes is analyzed. A transition from the constricted to the diffuse mode can be regarded as a manifestation of the nonlocal character of the formation of the electron distribution function, specifically, the diffusion of high-energy electrons capable of producing gas ionization from the central (constricted) region toward the periphery. The nonlocal formation of the distribution function is described by a nonlocal kinetic equation accounting for electron-electron collisions and electron transport along the radius of the discharge tube. Since only high-energy electrons produce gas ionization, the effect of the nonlocal formation of the electron distribution function is taken into account by introducing the effective temperature of the high-energy part of the distribution function and solving the equation for the radial profile of the high-energy part of the distribution function. This approach allows one to approximately take into account the nonlocal character of the electron distribution function without substantial expenditure of computer resources. The nonlocal model makes it possible to numerically simulate the hysteresis transition between the diffuse and constricted modes, which is impossible in the local approximation.

  11. Characterization of intrinsic hysteresis of pentacene-based organic thin-film transistor through in-situ real-time electrical measurement

    NASA Astrophysics Data System (ADS)

    Su, Wei-Cheng; Lee, Chih-Chien; Liu, Shun-Wei; Wang, Wei-Lun; Wen, Je-Min; Ho, Yu-Hsuan; Lin, Chun-Feng

    2014-01-01

    The intrinsic hysteresis of a pentacene-based organic thin-film transistor was characterized through home-designed in-situ real-time electrical measurement. The device exhibited intrinsic hysteresis after the device fabrication without breaking the vacuum, which has not been observed previously. Similar behavior was observed when introducing the nitrogen gas. Compared with the measurement condition of vacuum or nitrogen gas, exposure to the ambient air resulted in a severe hysteresis. It was attributed to both the acceptor-like traps at the organic/dielectric interface and the donor-like traps in the transport channel. When the chamber was vacuumed out again, a significantly reduced hysteresis was obtained almost the same as that measured just after device fabrication, indicating the reversibility of the extrinsic hysteresis. We also related the hysteresis to the morphological change under different deposition rates of pentacene. The smoother surface at higher deposition rate caused reduced hysteresis because of the elimination of vacancies near the pentacene/dielectric interface.

  12. Drift and Hysteresis Effects on AlN/SiO2 Gate pH Ion-Sensitive Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

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

    2003-08-01

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

  13. Abiotic and biotic controls of soil moisture spatiotemporal variability and the occurrence of hysteresis

    NASA Astrophysics Data System (ADS)

    Fatichi, Simone; Katul, Gabriel G.; Ivanov, Valeriy Y.; Pappas, Christoforos; Paschalis, Athanasios; Consolo, Ada; Kim, Jongho; Burlando, Paolo

    2015-05-01

    An expression that separates biotic and abiotic controls on the temporal dynamics of the soil moisture spatial coefficient of variation Cv(θ) was explored via numerical simulations using a mechanistic ecohydrological model, Tethys-Chloris. Continuous soil moisture spatiotemporal dynamics at an exemplary hillslope domain were computed for six case studies characterized by different climate and vegetation cover and for three configurations of soil properties. It was shown that abiotic controls largely exceed their biotic counterparts in wet climates. Biotic controls on Cv(θ) were found to be more pronounced in Mediterranean climates. The relation between Cv(θ) and spatial mean soil moisture θ¯ was found to be unique in wet locations, regardless of the soil properties. For the case of homogeneous soil texture, hysteretic cycles between Cv(θ) and θ¯ were observed in all Mediterranean climate locations considered here and to a lesser extent in a deciduous temperate forest. Heterogeneity in soil properties increased Cv(θ) to values commensurate with field observations and weakened signatures of hysteresis at all of the studied locations. This finding highlights the role of site-specific heterogeneities in hiding or even eliminating the signature of climatic and biotic controls on Cv(θ), thereby offering a new perspective on causes of confounding results reported across field experiments.

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

    SciTech Connect

    Dahmen, K.; Sethna, J.P.

    1996-06-01

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

  15. Breaking an Epigenetic Chromatin Switch: Curious Features of Hysteresis in Saccharomyces cerevisiae Telomeric Silencing

    PubMed Central

    Nagaraj, Vijayalakshmi H.; Mukhopadhyay, Swagatam; Dayarian, Adel; Sengupta, Anirvan M.

    2014-01-01

    In addition to gene network switches, local epigenetic modifications to DNA and histones play an important role in all-or-none cellular decision-making. Here, we study the dynamical design of a well-characterized epigenetic chromatin switch: the yeast SIR system, in order to understand the origin of the stability of epigenetic states. We study hysteresis in this system by perturbing it with a histone deacetylase inhibitor. We find that SIR silencing has many characteristics of a non-linear bistable system, as observed in conventional genetic switches, which are based on activities of a few promoters affecting each other through the abundance of their gene products. Quite remarkably, our experiments in yeast telomeric silencing show a very distinctive pattern when it comes to the transition from bistability to monostability. In particular, the loss of the stable silenced state, upon increasing the inhibitor concentration, does not seem to show the expected saddle node behavior, instead looking like a supercritical pitchfork bifurcation. In other words, the off state merges with the on state at a threshold concentration leading to a single state, as opposed to the two states remaining distinct up to the threshold and exhibiting a discontinuous jump from the off to the on state. We argue that this is an inevitable consequence of silenced and active regions coexisting with dynamic domain boundaries. The experimental observations in our study therefore have broad implications for the understanding of chromatin silencing in yeast and beyond. PMID:25536038

  16. Feature evaluation of complex hysteresis smoothing and its practical applications to noisy SEM images.

    PubMed

    Suzuki, Kazuhiko; Oho, Eisaku

    2013-01-01

    Quality of a scanning electron microscopy (SEM) image is strongly influenced by noise. This is a fundamental drawback of the SEM instrument. Complex hysteresis smoothing (CHS) has been previously developed for noise removal of SEM images. This noise removal is performed by monitoring and processing properly the amplitude of the SEM signal. As it stands now, CHS may not be so utilized, though it has several advantages for SEM. For example, the resolution of image processed by CHS is basically equal to that of the original image. In order to find wide application of the CHS method in microscopy, the feature of CHS, which has not been so clarified until now is evaluated correctly. As the application of the result obtained by the feature evaluation, cursor width (CW), which is the sole processing parameter of CHS, is determined more properly using standard deviation of noise N?. In addition, disadvantage that CHS cannot remove the noise with excessively large amplitude is improved by a certain postprocessing. CHS is successfully applicable to SEM images with various noise amplitudes. PMID:23184364

  17. Metastable nanobubbles at the solid-liquid interface due to contact angle hysteresis.

    PubMed

    Nishiyama, Takashi; Yamada, Yutaka; Ikuta, Tatsuya; Takahashi, Koji; Takata, Yasuyuki

    2015-01-27

    Nanobubbles exist at solid-liquid interfaces between pure water and hydrophobic surfaces with very high stability, lasting in certain cases up to several days. Not only semispherical but also other shapes, such as micropancakes, are known to exist at such interfaces. However, doubt has been raised as to whether or not the nanobubbles are gas-phase entities. In this study, surface nanobubbles at a pure water-highly ordered pyrolytic graphite (HOPG) interface were investigated by peak force quantitative nanomechanics (PF-QNM). Multiple isolated nanobubbles generated by the solvent-exchange method were present on the terraced areas, avoiding the steps of the HOPG surface. Adjacent nanobubbles coalesced and formed metastable nanobubbles. Coalescence was enhanced by the PF-QNM measurement. We determined that nanobubbles can exist for a long time because of nanoscale contact angle hysteresis at the water-HOPG interface. Moreover, the hydrophilic steps of HOPG were avoided during coalescence, providing evidence that the nanobubbles are truly gas phase. PMID:25540821

  18. 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.

  19. Thermal and quantum fluctuation effects in rotational hysteresis of ring Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Edwards, M.; Heller, C.; Wang, Y.-H.; Clark, C. W.

    2015-05-01

    In a recent experiment a ring Bose-Einstein condensate (BEC) with zero circulation (with winding number m = 0) and stirred by a barrier jumped to an m = 1 state when stirred faster than a certain critical speed, ?+ c. Conversely an m = 1 condensate dropped to m = 0 when stirred below a critical speed, ?? c, which was lower than ?+ c. The hysteresis loop areas, ?+ c -?- c , disagreed significantly with the predictions of the zero-temperature Gross-Pitaevskii equation. We report the results of simulating this experiment with both the Zaremba-Nikuni-Griffin (ZNG) theory and the Truncated Wigner Approximation (TWA). The ZNG theory can account for thermal fluctuations while the TWA can also account for quantum fluctations of the gas. We compare the results of these simulations with the experimental data and describe how the dynamics of vortex/antivortex pairs formed in the barrier region during the stirring is modified by the presence of a thermal cloud and by quantum fluctuations beyond the mean field. Supported by NSF grants PHY-1068761 and ARO Atomtronics MURI.

  20. Thermal and quantum fluctuation effects in rotational hysteresis of ring Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Clark, C. W.; Wang, Y.-H.; Heller, C.; Edwards, M.

    2015-03-01

    In a recent experment a ring Bose-Einstein condensate (BEC) with zero circulation (with winding number m = 0) and stirred by a barrier jumped to an m = 1 state when stirred faster than a certain critical speed, ?c+. Conversely an m = 1 condensate dropped to m = 0 when stirred below a critical speed, ?c-, which was lower than ?c+. The hysteresis loop areas, ?c+ -?c- , disagreed significantly with the predictions of the zero-temperature Gross-Pitaevskii equation. We report the results of simulating this experiment with both the Zaremba-Nikuni-Griffin (ZNG) theory and the Truncated Wigner Approximation (TWA). The ZNG theory can account for thermal fluctuations while the TWA can also account for quantum fluctations of the gas. We compare the results of these simulations with the experimental data and describe how the dynamics of vortex/antivortex pairs formed in the barrier region during the stirring is modified by the presence of a thermal cloud and by quantum fluctuations beyond the mean field. Supported by NSF Grants PHY-1068761 and ARO Atomtronics MURI.