Sample records for p-e hysteresis loop

  1. Design of experiment for hysteresis loops measurement

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  2. A high-performance hysteresis loop tracer

    Microsoft Academic Search

    Tadeusz Kulik; Howard T. Savage; Antonio Hernando

    1993-01-01

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

  3. Magnetic Hysteresis Loop Tracer Using Operational Amplifiers

    Microsoft Academic Search

    Homer Fay

    1972-01-01

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

  4. A high-performance hysteresis loop tracer

    NASA Astrophysics Data System (ADS)

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

    1993-05-01

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

  5. Circuit measures hysteresis loop areas at 30 Hz

    NASA Technical Reports Server (NTRS)

    Hoffman, C.; Spilo, D.

    1967-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Iwata, Makoto; Ishibashi, Yoshihiro

    2005-09-01

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

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

    SciTech Connect

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

    2006-01-01

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

  8. Theory of the hysteresis loop in ferromagnets 

    E-print Network

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

    1999-01-01

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

  9. Clockwise Hysteresis Loops in the Macroscopic Fundamental Diagram

    E-print Network

    California at Berkeley, University of

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

  10. Minor hysteresis loops measurements for characterization of cast iron

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

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

    Microsoft Academic Search

    E. Cardeffi; Romano Giannetti; Bernardo Tellini

    2005-01-01

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

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

    E-print Network

    Tan, Xiaobo

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

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

    SciTech Connect

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

    2012-01-01

    The dependence of on-field and off-field hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.

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

    SciTech Connect

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

    2013-01-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  16. 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

  17. 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

  18. 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.

  19. Clockwise hysteresis loops in the Macroscopic Fundamental Diagram: An effect of network instability

    Microsoft Academic Search

    Vikash V. Gayah; Carlos F. Daganzo

    2011-01-01

    A recent study reported that the Macroscopic Fundamental Diagram of a medium size city exhibited a clockwise hysteresis loop on a day in which a major disturbance caused many drivers to use unfamiliar routes. It is shown below that, even in a perfectly symmetric network with uniform demand, clockwise loops are to be expected when there are disturbances, especially if

  20. A macroscopic theory for the existence of the hysteresis and butterfly loops in ferroelectricity

    Microsoft Academic Search

    Peter J. Chen; Stephen T. Montgomery

    1980-01-01

    We present in this paper a minimal macroscopic theory leading to the hysteresis loop and the butterfly loop in ferroelectricity. This theory is based on the notion that as domains switch under the action of an external electric field the number of dipoles aligned in the direction of the field also alters and it obeys a rate law which depends

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

    SciTech Connect

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

    2013-02-11

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

  2. 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.

  3. Element specific separation of bulk and interfacial magnetic hysteresis loops

    Microsoft Academic Search

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

    2007-01-01

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

  4. Investigation of the Temperature Hysteresis Phenomenon of a Loop Heat Pipe

    NASA Technical Reports Server (NTRS)

    Kaya, Tarik; Ku, Jentung; Hoang, Triem; Cheung, Mark K.

    1999-01-01

    The temperature hysteresis phenomenon of a Loop Heat Pipe (LHP) was experimentally investigated. The temperature hysteresis was identified by the fact that the operating temperature depends upon not only the imposed power but also the previous history of the power variation. The temperature hysteresis could impose limitations on the LHP applications since the LHP may exhibit different steady-state operating temperatures at a given power input even when the condenser sink temperature remains unchanged. In order to obtain insight to this phenomenon, a LHP was tested at different elevations and tilts by using an elaborated power profile. A hypothesis was suggested to explain the temperature hysteresis. This hypothesis explains well the experimental observations. Results of this study provide a better understanding of the performance characteristics of the LHPS.

  5. Quantum step heights in hysteresis loops of molecular magnets Roberto B. Diener,1

    E-print Network

    Niu, Qian

    Quantum step heights in hysteresis loops of molecular magnets Jie Liu,1 Biao Wu,1 Libin Fu,2 February 2002; published 16 May 2002 We present an analytical theory on the heights of the quantum steps molecular spins, our theory successfully yields the step heights measured in experiments, and reveals

  6. Influence of dielectric stiffness, interface, and layer thickness on hysteresis loops of ferroelectric superlattices

    Microsoft Academic Search

    K.-H. Chew; L.-H. Ong; M. Iwata

    2011-01-01

    We examined the influence of dielectric stiffness, interface, and layer thickness on the hysteresis loops, including the remanent polarization and coercive field of a superlattice comprising alternate layers of ferroelectric and dielectric, using the Landau-Ginzburg theory. An interface energy term is introduced in the free energy functional to describe the formation of interface “dead” layers that are mutually coupled through

  7. Influence of dielectric stiffness, interface, and layer thickness on hysteresis loops of ferroelectric superlattices

    Microsoft Academic Search

    K.-H. Chew; L.-H. Ong; M. Iwata

    2011-01-01

    We examined the influence of dielectric stiffness, interface, and layer thickness on the hysteresis loops, including the remanent polarization and coercive field of a superlattice comprising alternate layers of ferroelectric and dielectric, using the Landau-Ginzburg theory. An interface energy term is introduced in the free energy functional to describe the formation of interface ``dead'' layers that are mutually coupled through

  8. Segmented shape memory alloy actuators using hysteresis loop control

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

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

  9. Asymmetrically shaped hysteresis loop in exchange-biased FeNi/FeMn film

    NASA Astrophysics Data System (ADS)

    Gnatchenko, S. L.; Merenkov, D. N.; Bludov, A. N.; Pishko, V. V.; Shakhayeva, Yu. A.; Baran, M.; Szymczak, R.; Novosad, V. A.

    2006-12-01

    The magnetization reversal of the bilayer polycrystalline FeNi(50 Å)/FeMn(50 Å) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field applied along the easy axis. The specific features of magnetization reversal were explained within the phenomenological model that involves high-order exchange anisotropy and misalignment of the easy axes of the antiferromagnetic and ferromagnetic layers. It has been shown that the film can exist in one of three equilibrium magnetic states in the field applied along the easy axis. The transitions between these states occur as first-order phase transitions. The observed hysteresis loop asymmetry is related to the existence of the metastable state.

  10. Influence of dielectric stiffness, interface, and layer thickness on hysteresis loops of ferroelectric superlattices

    NASA Astrophysics Data System (ADS)

    Chew, K.-H.; Ong, L.-H.; Iwata, M.

    2011-09-01

    We examined the influence of dielectric stiffness, interface, and layer thickness on the hysteresis loops, including the remanent polarization and coercive field of a superlattice comprising alternate layers of ferroelectric and dielectric, using the Landau-Ginzburg theory. An interface energy term is introduced in the free energy functional to describe the formation of interface "dead" layers that are mutually coupled through polarization (or induced-polarization). Our studies reveal that the hysteresis loop is strongly dependent on the stiffness of the dielectric layer, the strength of the interface coupling and layer thickness. The intrinsic coupling at the interface between two neighboring layers reduces the coercive field, though the corresponding remanent polarization is significantly enhanced by a soft dielectric layer.

  11. Simulations of magnetic hysteresis loops at high temperatures

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The kinetic Monte-Carlo algorithm as well as standard micromagnetics are used to simulate MH loops of high anisotropy magnetic recording media at both short and long time scales over a wide range of temperatures relevant to heat-assisted magnetic recording. Microscopic parameters, common to both methods, were determined by fitting to experimental data on single-layer FePt-based media that uses the Magneto-Optic Kerr effect with a slow sweep rate of 700 Oe/s. Saturation moment, uniaxial anisotropy, and exchange constants are given an intrinsic temperature dependence based on published atomistic simulations of FePt grains with an effective Curie temperature of 680 K. Our results show good agreement between micromagnetics and kinetic Monte Carlo results over a wide range of sweep rates. Loops at the slow experimental sweep rates are found to become more square-shaped, with an increasing slope, as temperature increases from 300 K. These effects also occur at higher sweep rates, typical of recording speeds, but are much less pronounced. These results demonstrate the need for accurate determination of intrinsic thermal properties of future recording media as input to micromagnetic models as well as the sensitivity of the switching behavior of thin magnetic films to applied field sweep rates at higher temperatures.

  12. Simulations of magnetic hysteresis loops at high temperatures

    SciTech Connect

    Plumer, M. L.; Whitehead, J. P.; Fal, T. J. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X7 (Canada); Ek, J. van [Western Digital Corporation, San Jose, California 94588 (United States); Mercer, J. I. [Department of Computer Science, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X7 (Canada)

    2014-09-28

    The kinetic Monte-Carlo algorithm as well as standard micromagnetics are used to simulate MH loops of high anisotropy magnetic recording media at both short and long time scales over a wide range of temperatures relevant to heat-assisted magnetic recording. Microscopic parameters, common to both methods, were determined by fitting to experimental data on single-layer FePt-based media that uses the Magneto-Optic Kerr effect with a slow sweep rate of 700 Oe/s. Saturation moment, uniaxial anisotropy, and exchange constants are given an intrinsic temperature dependence based on published atomistic simulations of FePt grains with an effective Curie temperature of 680 K. Our results show good agreement between micromagnetics and kinetic Monte Carlo results over a wide range of sweep rates. Loops at the slow experimental sweep rates are found to become more square-shaped, with an increasing slope, as temperature increases from 300 K. These effects also occur at higher sweep rates, typical of recording speeds, but are much less pronounced. These results demonstrate the need for accurate determination of intrinsic thermal properties of future recording media as input to micromagnetic models as well as the sensitivity of the switching behavior of thin magnetic films to applied field sweep rates at higher temperatures.

  13. Asymmetrically shaped hysteresis loop in exchange-biased FeNi\\/FeMn film

    Microsoft Academic Search

    S. L. Gnatchenko; D. N. Merenkov; A. N. Bludov; V. V. Pishko; Yu. A. Shakhayeva; M. Baran; R. Szymczak; V. A. Novosad

    2006-01-01

    The magnetization reversal of the bilayer polycrystalline FeNi(50Å)\\/FeMn(50Å) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field

  14. Crystal Orientation and Temperature Effects on the Double Hysteresis Loop Behavior of a PVDF- g-PS Graft Copolymer

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Yang, Lianyun; Guan, Fangxiao

    2013-03-01

    In a recent report, double hysteresis loop behavior is observed in a nanoconfined poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene)-graft-polystyrene [P(VDF-TrFE-CTFE)- g-PS] copolymer. It is considered that the PS grafts are capable of reducing the compensation polarization and thus the polarization electric field during the reverse poling process, resulting in the double hysteresis loop behavior. In this study, we further investigated crystal orientation and temperature effects on this novel ferroelectric behavior. It is observed that with increasing the orientation factor, the electric displacement-electric field (D-E) loop changes from linear for non-oriented film to double loop for the well-oriented film. With increasing the temperature, the double hysteresis loop is gradually replaced by the single and open loop, which is attributed to the impurity ion migrational loss in the sample. In a recent report, double hysteresis loop behavior is observed in a nanoconfined poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene)-graft-polystyrene [P(VDF-TrFE-CTFE)- g-PS] copolymer. It is considered that the PS grafts are capable of reducing the compensation polarization and thus the polarization electric field during the reverse poling process, resulting in the double hysteresis loop behavior. In this study, we further investigated crystal orientation and temperature effects on this novel ferroelectric behavior. It is observed that with increasing the orientation factor, the electric displacement-electric field (D-E) loop changes from linear for non-oriented film to double loop for the well-oriented film. With increasing the temperature, the double hysteresis loop is gradually replaced by the single and open loop, which is attributed to the impurity ion migrational loss in the sample. This work is supported by NSF (DMR-0907580).

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  16. Defect-induced asymmetry of local hysteresis loops on BiFeO3 surfaces

    SciTech Connect

    Maksymovych, Petro [ORNL; Balke, Nina [ORNL; Jesse, Stephen [ORNL; Huijben, Mark [University of Twente, Enschede, Netherlands; Ramesh, R. [University of California, Berkeley; Baddorf, Arthur P [ORNL; Kalinin, Sergei V [ORNL

    2009-01-01

    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.

  17. Susceptibility and Inverted Hysteresis Loop of Prussian Blue Analogs with Orthorhombic Structure

    NASA Astrophysics Data System (ADS)

    Guo, An-Bang; Jiang, Wei

    2012-11-01

    The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in details. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri-ferrimagnet.

  18. 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.

  19. Exchange anisotropy in polycrystalline FeNi/FeMn films with hysteresis loop assymmetry.

    SciTech Connect

    Merenkov, D. N.; Bludov, A. N.; Gnatchenko, S. L.; Baran, M.; Szymczak, R.; Novosad, V. A.; Materials Science Division; National Academy of Sciences of Ukraine; Polish Academy of Sciences

    2007-11-01

    The process of magnetization reversal of a FeNi(50 {angstrom})/FeMn(50 {angstrom}) polycrystalline film prepared in a magnetic field has been investigated at temperatures ranging from 25 to 300 K. The external field was oriented in the film plane along the easy or difficult axis of the ferromagnetic layer. In the process of magnetization reversal of the film along the easy axis, strong asymmetry of the hysteresis loop is observed together with an exchange shift. As temperature decreases, the asymmetry becomes more pronounced and the shift increases. The field dependences of the magnetization of the film are symmetric and are not shifted when the external field is applied along the difficult axis. The magnetization reversal process is examined on the basis of a model that takes account of the appearance of high-order exchange anisotropy in polycrystalline films. It is shown that the observed strong asymmetry of the hysteresis loop is associated with the formation of a canted phase and the existence of a metastable state. As the film temperature decreases, the interval of fields where the canted phase can exist becomes wider as a result of an increase of the exchange anisotropy constants.

  20. Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities

    DOEpatents

    Humphrey, Floyd B. (Bradfordwoods, PA)

    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.

  1. A New Magnetic-Field Electron-Irradiation Treatment for Producing Low-Coersive-Force Rectangular Hysteresis Loops in Supermalloy

    Microsoft Academic Search

    D. I. Gordon; R. S. Sery

    1964-01-01

    True magnetic-annealing effects, i. e., hysteresis loops with high remanence and rectangularity, with no increase in coercive force, can be induced in flat ring samples of bulk .015 cm thick polycrystalline Supermalloy at low temperatures by a new electron-radiomagnetic treatment. This treatment is possible because radiation produces vacancies in excess of the thermal equilibrium number, and this excess of vacancies

  2. The magnetization process: Hysteresis

    NASA Technical Reports Server (NTRS)

    Balsamel, Richard

    1990-01-01

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

  3. Physical motivations of the constitutive relations for ferroelectric ceramics and the existence of butterfly and hysteresis loops

    SciTech Connect

    Chen, P.J.

    1982-01-01

    The responses of ferroelectric ceramics can be quite complex depending on the physical processes to which they are subjected. Their mechanical, electromechanical and dielectric properties depend on domain switching, dipole dynamics and phase transformation which can be caused by external stimuli such as mechanical and electrical loadings, and temperature variations. A theory, taking into account the effects of domain switching and dipole dynamics, has been formulated, and in its present stage of development is sufficient to characterize various observable resonses. Specifically, a special case of the theory predicts the nature of the butterfly and hysteresis loops. The butterfly and hysteresis loops are manifestations of the mechanical, electro-mechanical and dielectric responses due to domain switching produced by cyclic electric fields. Comparisons of the predictions of the theory with experimental results are made in a pseudo one dimensional context.

  4. Study of thermal ageing behaviour of Fe-Cr model alloys by magnetic hysteresis loop technique

    NASA Astrophysics Data System (ADS)

    Mohapatra, J. N.; Kamada, Y.; Kikuchi, H.; Kobayashi, S.; Echigoya, J.; Park, D. G.; Cheong, Y. M.

    2011-01-01

    Fe-Cr alloys with different Cr content (5-20 wt. %) were prepared by arc melting technique. The alloys were solution annealed at 1050 oC/ 2h and air quenched and then tempered at 750 oC/ 1h followed by air cooling. Thermal ageing was carried at 475 oC for various lengths of time up to 1000 hours (hrs) to produce thermal embrittlement. The hardness and coercivity of Fe-20% Cr alloys were increased and the remanence was decreased, being due to the precipitation of Cr-rich a' phase and their subsequent growth. In Fe-15% Cr and Fe-10% Cr alloys, it was found that the coercivity decreased at the initial ageing period and then increased subsequently due to the competing effect of recovery of dislocations and precipitation of Cr rich phase. The change in magnetic properties in Fe-5% Cr alloy was different than other alloys since it was within the solubility limit of Cr in Fe. A linear relationship was found between the coercivity and hardness in Fe-20% Cr alloy, indicating that Magnetic Hysteresis Loop (MHL) technique would be a good tool for the Non-Destructive Evaluatiion (NDE) of embrittlement in Fe-Cr alloys.

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

    Microsoft Academic Search

    N. Schmidt; H. Guldner

    1996-01-01

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

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

    Microsoft Academic Search

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

    1994-01-01

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

  7. Hysteresis loop and pattern from the dual-wavelength competition in an Nd:YVO4 laser with an intracavity periodically poled lithium niobate Bragg modulator

    NASA Astrophysics Data System (ADS)

    Hong, Kun-Guei; Lin, Shou-Tai; Wei, Ming-Dar

    2014-10-01

    This study demonstrates hysteresis loop and pattern formation in a Nd:YVO4 laser at 1064nm (4F3/2 ?4I1 1/2) and 1342nm (4F3/2?4I13/2) with an intracavity electro-optic periodically poled lithium niobate (EO PPLN) Bragg modulator by using a T-type cavity configuration. Based on these dual wavelengths sharing population inversion in the same upper energy level to lase, the transmission, Tp, of EO PPLN was chosen as the controlling parameter to explore the dynamics of dualwavelength competition. A hysteresis loop occurred when the extracting efficiencies of dual wavelength were near equivalent. When the pump power was 9.0 W, the hysteresis loop was observed in the region of the transmission of PPLN between Tp=64.88% to Tp=84.47%. The slope efficiencies were 25.96 and 3.92% and the thresholds were 2.5 and 3.5 W for the wavelengths of 1064 and 1342 nm, respectively. The width of the hysteresis loop increased when the pump power increased. Moreover, the hysteresis loop accompanied with the variation of the pattern formation. A high-order transvers mode was easily observed at 1342 nm light, but a simple spot existed for 1064 nm light. Apparently, the role of gain competition is worthy to deeply explore.

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

    Microsoft Academic Search

    Jan Szczyg?owski

    2001-01-01

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

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

    Microsoft Academic Search

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1987-04-01

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

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

    E-print Network

    Gulak, P. Glenn

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

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

    E-print Network

    Sheikholeslami, Ali

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

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

    SciTech Connect

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

    2011-02-15

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

  14. Experiments on snap buckling, hysteresis and loop formation in twisted rods.

    E-print Network

    Neukirch, Sébastien

    deflection experiments involving the bending and twisting of 1 mm diameter nickel­titanium alloy rods, up, snap buckling, loop formation, snarling, hock­ ling, welded boundary conditions. 1 Introduction

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Experiments on Snap Buckling, Hysteresis and Loop Formation in Twisted Rods

    E-print Network

    Neukirch, Sébastien

    experi- ments involving the bending and twisting of 1 mm diameter nickel­titanium alloy rods, up to 2 m, rod experiments, snap buckling, loop formation, snarling, hockling, welded boundary condi- tions applications include V.G.A. Goss (gossga@lsbu.ac.uk) is a PhD Student, Welding Technician and Lecturer,G.H.M

  17. Photo-induced bias of the hysteresis loop in ferrites at room temperature with long-time memory

    NASA Astrophysics Data System (ADS)

    Katsnelson, E. Z.; Chervinsky, M. M.

    2009-09-01

    New photo-magnetic effects with an indefinitely long-time memory are found at room temperature in the epitaxial Mg 0.75Mn 0.21Co 0.04Fe 2O 4 ferrite film. Illumination of the ferrimagnetic material with low-intensity (0.4 W cm -2) circularly polarized light with or without a static magnetic field in the Faraday effect geometry results in a number of nonlinear effects in both space and time. In a uniform crystal with cubic symmetry, the long-lived photo-induced magnetization (PIM) with a unidirectional anisotropy appears along the direction of the incoming light. The effects depend on a combination of magnetic field H and the helicity of circularly polarized light ?. Two combinations H+, ?+ and H-, ?- lead to a photo-induced unidirectional anisotropy with a shift of the hysteresis loop along an applied field and a change in loop parameters. The loop contracts by a factor of two, the shift of the mid-point Hsh increases by factor of five surpassing the coercivity Hc, the coercivity Hc1 and remanence Mr1 (for decreasing applied field) reverse the sign, increasing by 9 Oe and reducing by a factor of 4.5, respectively. The effects cannot be erased by a conventional demagnetization (using an AC current that is reduced to zero amplitude), but can be removed using an illumination with two other combinations ( H+, ?- and H-, ?+) as well as by heating at temperatures higher than the Curie temperature. This long-lived room-temperature memory effect may arise from the formation of complex photo-induced defects including photo-induced magnetic polarons. The possible mechanisms responsible for the appearance of a room-temperature photo-induced unidirectional anisotropy with a long-lived memory are discussed. These new photo-magnetic effects may find an application in magneto-optical memory devices.

  18. Hysteresis in the Sky

    E-print Network

    Choudhury, Sayantan

    2015-01-01

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

  19. Triimidosulfonates as Acute Bite-Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co(II) Complex.

    PubMed

    Carl, Elena; Demeshko, Serhiy; Meyer, Franc; Stalke, Dietmar

    2015-07-01

    Starting from a polyimido sulfonate the four-coordinate, N,N'-chelated Co(II) complex [Co{(NtBu)3 SMe}2 ] (1) was synthesized, and its molecular structure was elucidated by single-crystal X-ray structural analysis. The acute N-Co-N bite angle imposed by the N,N'-chelating ligand (NtBu)3 SMe(-) leads to pronounced C2v distortion of the tetrahedral coordination environment and thus to high anisotropy of the Co(II) ion (D?-58?cm(-1) ), favorable for single-molecule-magnet (SMM) properties. Magnetic measurements revealed a high barrier to spin reversal (Ueff =75?cm(-1) ) that gives rise to the observation of slow relaxation of the magnetization in zero field and a hysteresis loop at 2?K for this unique complex. PMID:26043416

  20. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Technical Reports Server (NTRS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  1. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Technical Reports Server (NTRS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  2. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    SciTech Connect

    Wieserman, W.R. [Univ. of Pittsburgh, Johnstown, PA (United States); Schwarze, G.E. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Niedra, J.M. [Sverdrup Technology, Inc., Brook Park, OH (United States). Lewis Research Center Group

    1994-09-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglass 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  3. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Astrophysics Data System (ADS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  4. High Frequency, High Temperature Specific Core Loss and Dynamic BH Hysteresis Loop Characteristics of Soft Magnetic Alloys

    Microsoft Academic Search

    W. R. Wieserman; G. E. Schwarze; J. M. Niedra

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for s oft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 C under

  5. High frequency, high temperature specific core loss and dynamic BH hysteresis loop characteristics of soft magnetic alloys

    Microsoft Academic Search

    W. R. Wieserman; G. E. Schwarze; J. M. Niedra

    1994-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglass 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 C under sinusoidal

  6. High frequency, high temperature specific core loss and dynamic BH hysteresis loop characteristics of soft magnetic alloys

    Microsoft Academic Search

    W. R. Wieserman; G. E. Schwarze; J. M. Niedra

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to

  7. Mathematical models of hysteresis

    SciTech Connect

    NONE

    1998-08-01

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

  8. Simultaneous effects of surface spins: rarely large coercivity, high remanence magnetization and jumps in the hysteresis loops observed in CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, S. T.; Ma, Y. Q.; Zheng, G. H.; Dai, Z. X.

    2015-04-01

    Well-dispersed uniform cobalt ferrite nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point. Some of the nanoparticles were diluted in a SiO2 matrix and then the undiluted and diluted samples were characterized and their magnetic behavior explored. The undiluted and diluted samples exhibited maximum coercivity Hc of 23 817 and 15 056 Oe at 10 K, respectively, which are the highest values reported to date, and the corresponding ratios of remanence (Mr) to saturation (Ms) magnetization (Mr/Ms) were as high as 0.85 and 0.76, respectively. Interestingly, the magnetic properties of the samples changed at 200 K, which was observed in magnetic hysteresis M(H) loops and zero-field cooling curves as well as the temperature dependence of Hc, Mr/Ms, anisotropy, dipolar field, and the magnetic grain size. Below 200 K, both samples have large effective anisotropy, which arises from the surface spins, resulting in large Hc and Mr/Ms. Above 200 K, the effective anisotropy decreases because there is no contribution from surface spins, while the dipolar interaction increases, resulting in small Hc and Mr/Ms. Our results indicate that strong anisotropy and weak dipolar interaction tend to increase Hc and Mr/Ms, and also clarify that the jumps around H = 0 in M(H) loops can be attributed to the reorientation of surface spins. This work exposes the underlying mechanism in nanoscale magnetic systems, which should lead to improved magnetic performance.

  9. Simultaneous effects of surface spins: rarely large coercivity, high remanence magnetization and jumps in the hysteresis loops observed in CoFe2O4 nanoparticles.

    PubMed

    Xu, S T; Ma, Y Q; Zheng, G H; Dai, Z X

    2015-04-21

    Well-dispersed uniform cobalt ferrite nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point. Some of the nanoparticles were diluted in a SiO2 matrix and then the undiluted and diluted samples were characterized and their magnetic behavior explored. The undiluted and diluted samples exhibited maximum coercivity Hc of 23,817 and 15,056 Oe at 10 K, respectively, which are the highest values reported to date, and the corresponding ratios of remanence (Mr) to saturation (Ms) magnetization (Mr/Ms) were as high as 0.85 and 0.76, respectively. Interestingly, the magnetic properties of the samples changed at 200 K, which was observed in magnetic hysteresis M(H) loops and zero-field cooling curves as well as the temperature dependence of Hc, Mr/Ms, anisotropy, dipolar field, and the magnetic grain size. Below 200 K, both samples have large effective anisotropy, which arises from the surface spins, resulting in large Hc and Mr/Ms. Above 200 K, the effective anisotropy decreases because there is no contribution from surface spins, while the dipolar interaction increases, resulting in small Hc and Mr/Ms. Our results indicate that strong anisotropy and weak dipolar interaction tend to increase Hc and Mr/Ms, and also clarify that the jumps around H = 0 in M(H) loops can be attributed to the reorientation of surface spins. This work exposes the underlying mechanism in nanoscale magnetic systems, which should lead to improved magnetic performance. PMID:25787852

  10. Preisach modeling of piezoceramic and shape memory alloy hysteresis

    Microsoft Academic Search

    Declan Hughes; John T. Wen

    1995-01-01

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

  11. Hysteresis Simulation

    NSDL National Science Digital Library

    Paul Houle

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

  12. Specification of distribution functions for magnetic hysteresis modeling

    Microsoft Academic Search

    A. Pruksanubal

    2009-01-01

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

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

    Microsoft Academic Search

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

    1996-01-01

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

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

    Microsoft Academic Search

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

    1971-01-01

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

  15. Origin of recoil hysteresis loops in SmCo/Fe exchange-spring magnets J. S. Jiang, J. E. Pearson, and S. D. Bader

    E-print Network

    Liu, J. Ping

    ­Co/Fe exchange spring magnets, the authors found that the open recoil loops were present not only in the soft Fe anisotropy of a mag- netically hard phase and the high saturation moment of a magnetically soft phase field to a magnetic material, as the demagnetizing field is increased successively. Open recoil loops

  16. Hysteresis Modeling in An ElectroMagnetic Transients Program

    Microsoft Academic Search

    James Frame; Narendra Mohan; Tsu-huei Liu

    1982-01-01

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

  17. Large capacitance-voltage hysteresis loops in SiO{sub 2} films containing Ge nanocrystals produced by ion implantation and annealing

    SciTech Connect

    Park, C.J.; Cho, K.H.; Yang, W.-C.; Cho, H.Y.; Choi, Suk-Ho; Elliman, R.G.; Han, J.H.; Kim, Chungwoo [Department of Physics and Quantum-Functional Semiconductor Research Center, Dongguk University, Seoul 100-715 (Korea, Republic of); Department of Physics and Applied Physics, College of Electronics and Informations, Kyung Hee University, Suwon 449-701 (Korea, Republic of); Electronic Materials Engineering Department, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT0200 (Australia); Semiconductor R and D Center Memory Division, Samsung Electronics Co. LTD., Kyunggi-do, 449-711 (Korea, Republic of)

    2006-02-13

    Metal-oxide-semiconductor structures containing Ge nanocrystals (NCs) of 3-4 nm diameter and 2x10{sup 12} cm{sup -2} density are shown to exhibit capacitance-voltage hysteresis of 20.9 V, one of the largest observed in Ge-NC based nonvolatile memories. The Ge NCs were fabricated in an oxide of 30 nm thickness by ion implantation with 30 keV Ge{sub 2}{sup -} ions to an equivalent fluence of 1x10{sup 16} Ge cm{sup -2} followed by annealing at 950 deg. C for 10 min. Secondary ion mass spectroscopy and transmission electron microscopy demonstrate the existence of Ge NCs whose average distance from the SiO{sub 2}/Si interface is about 6.7 nm. It is shown that the memory effect is a likely consequence of charge trapping at Ge NCs and that it is enhanced by accurately controlling the distribution of Ge NCs with respect to the Si/SiO{sub 2} interface.

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

    E-print Network

    Weidner, John W.

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

  19. Dynamic hysteresis control of lift on a pitching wing

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. Efficient Computational Model of Hysteresis

    NASA Technical Reports Server (NTRS)

    Shields, Joel

    2005-01-01

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

  1. Strategy for stabilization of the antiferroelectric phase (Pbma) over the metastable ferroelectric phase (P21ma) to establish double loop hysteresis in lead-free (1-x)NaNbO3-xSrZrO3 solid solution

    NASA Astrophysics Data System (ADS)

    Guo, Hanzheng; Shimizu, Hiroyuki; Mizuno, Youichi; Randall, Clive A.

    2015-06-01

    A new lead-free antiferroelectric solid solution system, (1-x)NaNbO3-xSrZrO3, was rationalized through noting the crystal chemistry trend, of decreasing the tolerance factor and an increase in the average electronegativity of the system. The SrZrO3 doping was found to effectively stabilize the antiferroelectric (P) phase in NaNbO3 without changing its crystal symmetry. Preliminary electron diffraction and polarization measurements were presented which verified the enhanced antiferroelectricity. In view of our recent report of another lead-free antiferroelectric system (1-x)NaNbO3-xCaZrO3 [H. Shimizu et al. "Lead-free antiferroelectric: xCaZrO3 - (1-x)NaNbO3 system (0 ? x ? 0.10)," Dalton Trans. (published online)], the present results point to a general strategy of utilizing tolerance factor to develop a broad family of new lead-free antiferroelectrics with double polarization hysteresis loops. We also speculate on a broad family of possible solid solutions that could be identified and tested for this important type of dielectric.

  2. Hysteresis in Metal Hydrides.

    ERIC Educational Resources Information Center

    Flanagan, Ted B., And Others

    1987-01-01

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

  3. Plant thermal hysteresis proteins.

    PubMed

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

    1992-05-22

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

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

    NASA Astrophysics Data System (ADS)

    Ho, Kwangsoo

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1992-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  7. Hysteresis in soft magnetic materials

    Microsoft Academic Search

    Vittorio Basso; Giorgio Bertotti

    2000-01-01

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

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

    Microsoft Academic Search

    Anant R. Kukreti; Ali S. Abolmaali

    1999-01-01

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

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

    Microsoft Academic Search

    Benedetta Cerruti; Eduard Vives

    2008-01-01

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

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

    E-print Network

    Sun, Qing-Ping

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

  12. Hysteresis of ionization waves

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  13. A Micromechanics-Based Hysteresis Model for Ferroelectric Ceramics

    Microsoft Academic Search

    J. Li; G. J. Weng

    2001-01-01

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

  14. Instantaneous Feedback Controlled PWM Inverter with Adaptive Hysteresis

    Microsoft Academic Search

    Atsuo Kawamura; Richard Hoft

    1984-01-01

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

  15. Experimental Testing Of An Anisotropic Vector Hysteresis Model

    Microsoft Academic Search

    A. Bergqvist; A. Lundgren; G. Engdahl

    1997-01-01

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

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

    Microsoft Academic Search

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

    2006-01-01

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

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

    Microsoft Academic Search

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

    2005-01-01

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

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

    Microsoft Academic Search

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

    1991-01-01

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

  19. An Energy-Based Hysteresis Model for Magnetostrictive Transducers

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.

    1976-01-01

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

  1. Dynamic hysteresis in cyclic deformation of crystalline solids.

    PubMed

    Laurson, Lasse; Alava, Mikko J

    2012-10-12

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  3. The New P.E.

    ERIC Educational Resources Information Center

    Vandertie, Joan; Corner, Amy B.; Corner, Kevin J.

    2012-01-01

    Marana Middle School in Tucson, Ariz., scrapped its traditional P.E. program that emphasized team sports and shifted to a program that focuses on lifetime fitness, student choice in activities, and nutrition and health education. The program also includes student leadership development and informal community service. As a result, Marana students…

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

    SciTech Connect

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

    2001-06-01

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

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

    SciTech Connect

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

    2014-02-18

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

  6. Applications of a theory of ferromagnetic hysteresis

    SciTech Connect

    Hodgdon, M.L.

    1987-01-01

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

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

    Microsoft Academic Search

    Hsin-Hsiung Wang; Miroslav KrstiC; Michael Larsen

    1997-01-01

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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    We study the first-order quantum phase transitions of Bose gases in optical lattices. A special emphasis is placed on an anomalous hysteresis behavior, in which the phase transition occurs in a unidirectional way and a hysteresis loop does not form. We first revisit the hardcore Bose-Hubbard model with dipole-dipole interactions on a triangular lattice to analyze accurately the ground-state phase diagram and the hysteresis using the cluster mean-field theory combined with cluster-size scaling. Details of the anomalous hysteresis are presented. We next consider the two-component and spin-1 Bose-Hubbard models on a hypercubic lattice and show that the anomalous hysteresis can emerge in these systems as well. In particular, for the former model, we discuss the experimental feasibility of the first-order transitions and the associated hysteresis. We also explain an underlying mechanism of the anomalous hysteresis by means of the Ginzburg-Landau theory. From the given cases, we conclude that the anomalous hysteresis is a ubiquitous phenomenon of systems with a phase region of lobe shape that is surrounded by the first-order boundary.

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

    PubMed

    Gu, Guoying; Zhu, Limin

    2010-08-01

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

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

    SciTech Connect

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

    2009-10-09

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

  12. 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)].

  13. Hysteresis Losses in Rolling and Sliding Friction

    Microsoft Academic Search

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

    1961-01-01

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

  14. Hysteresis errors of commonly used sensor materials

    Microsoft Academic Search

    Bulent Aydemir; Levent Yagmur; Sinan Fank

    2010-01-01

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

  15. arXiv:1406.6845v1[cond-mat.dis-nn]26Jun2014 Avalanches and hysteresis in frustrated superconductors and XY-spin-glasses

    E-print Network

    Müller, Markus

    arXiv:1406.6845v1[cond-mat.dis-nn]26Jun2014 Avalanches and hysteresis in frustrated superconductors. 38, 01187 Dresden, Germany (Dated: June 27, 2014) We study avalanches along the hysteresis loop by the softest mode of the inverse susceptibility matrix becoming unstable, which induces an avalanche of phase

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Drincic, Bojana

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

  19. 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

  20. Generalized formulation for the description of hysteresis in soft magnetic materials

    Microsoft Academic Search

    Paiboon Nakmahachalasint; Khai D. T. Ngo

    2002-01-01

    Presents a phenomenological formulation that broadens the range of applicability of the Basso-Bertotti hysteresis model to include soft magnetic materials with very gradual saturation, such as commercial manganese-zinc (MnZn) power ferrites. The formulation also enables the Basso-Bertotti model to better characterize both the major loop and the minor loops of these soft magnetic materials. The formulation introduces a model parameter

  1. Method for the measurement of anisotropy and rotational hysteresis using linear dichroism

    SciTech Connect

    Antel, W. J.; Coulthard, I.; Freeland, J. W.; Stampfl, A. P. J.; Schwickert, M. M.

    2001-08-13

    A technique combining x-ray magnetic linear dichroism absorption spectroscopy and rotational hysteresis loops is demonstrated. This technique, x-ray magnetic linear loops (XMLL), is used to extract magnetocrystalline anisotropy information. Results from two systems, a polycrystalline Fe film, and an epitaxial Fe film which exhibit different magnetic anisotropies, are shown. The measured XMLL is described using a simple single-domain anisotropy model. {copyright} 2001 American Institute of Physics.

  2. The effect of pore-structure on hysteresis in relative permeability and capillary pressure: Pore-level modeling

    Microsoft Academic Search

    G. R. Jerauld; S. J. Salter

    1990-01-01

    The effect of pore-structure upon two-phase relative permeability and capillary pressure of strongly-wetting systems at low capillary number is simulated. A pore-level model consisting of a network of pore-bodies interconnected by pore-throats is used to calculate scanning loops of hysteresis between primary drainage, imbibition and secondary drainage. The pore-body to pore-throat aspect ratio strongly influences the pattern of hysteresis. Changes

  3. Ionically-mediated electromechanical hysteresis in transition metal oxides

    SciTech Connect

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

    2012-01-01

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

  4. Hysteresis and Wavenumber Vacillation in Unstable Baroclinic Flows

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Xiangjiang; Alici, Gursel; Tan, Xiaobo

    2014-02-01

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

  6. Modelling hysteresis in magnetically ordered materials

    NASA Astrophysics Data System (ADS)

    Song, Tiancheng

    2003-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Friedman, G.

    1990-05-01

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

  10. NONLINEAR SEMIGROUP METHODS IN PROBLEMS WITH HYSTERESIS

    Microsoft Academic Search

    Jana Kopfov

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

  11. Wavelet implementation of Preisach model of hysteresis

    Microsoft Academic Search

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

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Rosinberg, M. L.; Tarjus, G.

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  14. 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.

  15. P E R S P E C T I V E www.rsc.org/obc

    E-print Network

    Hergenrother, Paul J.

    investigating the use of small molecules to define new targets for the treatment of cancer, neurodegenerativeP E R S P E C T I V E OBC www.rsc.org/obc Bacterial death comes full circle: targeting plasmid, plasmids offer novel targets that have heretofore been unexploited clinically. This Perspective details

  16. Hysteresis nonlinearity identification by using RBF neural network approach

    Microsoft Academic Search

    Mohsen Firouzi; Saeed Bagheri Shouraki; Mohammad Reza Zakerzadeh

    2010-01-01

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

  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. The influence of laminar separation and transition on low Reynolds number airfoil hysteresis

    NASA Technical Reports Server (NTRS)

    Mueller, T. J.

    1984-01-01

    An experimental study of the Lissaman 7769 and Miley MO6-13-128 airfoils at low chord Reynolds numbers is presented. Although both airfoils perform well near their design Reynolds number of about 600,000, they each produce a different type of hysteresis loop in the lift and drag forces when operated below chord Reynolds numbers of 300,000. The type of hysteresis loop was found to depend upon the relative location of laminar separation and transition. The influence of disturbance environment and experimental procedure on the low Reynolds number airfoil boundary layer behavior is also presented. The use of potential flow solutions to help predict how a given airfoil will behave at low Reynolds numbers is also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

  20. 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. (Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501 (United States))

    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.

  1. Spatial versus time hysteresis in damping mechanisms

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  2. 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.

  3. Hysteresis in neural-type circuits

    Microsoft Academic Search

    N. El-Leithy; R. W. Newcomb

    1988-01-01

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

  4. Hysteresis effects in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Sacchetti, Andrea

    2010-07-01

    Here, we consider damped two-component Bose-Einstein condensates with many-body interactions. We show that, when the external trapping potential has a double-well shape and when the nonlinear coupling factors are modulated in time, hysteresis effects may appear under some circumstances. Such hysteresis phenomena are a result of the joint contribution of the appearance of saddle node bifurcations and the damping effect.

  5. Hysteresis during contact angles measurement.

    PubMed

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

    2010-03-15

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

  6. 1—MOISTURE RELATIONS OF CELLULOSE. III. SORPTION HYSTERESIS AND THE EFFECT OF TEMPERATURE

    Microsoft Academic Search

    M. Wahba; S. Nashed

    1957-01-01

    Adsorption–desorption cycles of water vapour on ‘stabilized’ standard cellulose from dryness to saturation have been determined at 20°C, 30°C and 40°C. The 4O°C and 30°C adsorption isotherms are closer together than the 30°C and 20°C ones. The hysteresis loop at low relative humidity is considerably wider at 40°C than at the lower temperatures.Isosteric evaluation of the heats of sorption by

  7. 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.

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

    SciTech Connect

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

    2010-01-01

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

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

    E-print Network

    Leslie, Heather

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

  10. 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.

  11. Tracking Control of Shape-Memory-Alloy Actuators Based on Self-Sensing Feedback and Inverse Hysteresis Compensation

    PubMed Central

    Liu, Shu-Hung; Huang, Tse-Shih; Yen, Jia-Yush

    2010-01-01

    Shape memory alloys (SMAs) offer a high power-to-weight ratio, large recovery strain, and low driving voltages, and have thus attracted considerable research attention. The difficulty of controlling SMA actuators arises from their highly nonlinear hysteresis and temperature dependence. This paper describes a combination of self-sensing and model-based control, where the model includes both the major and minor hysteresis loops as well as the thermodynamics effects. The self-sensing algorithm uses only the power width modulation (PWM) signal and requires no heavy equipment. The method can achieve high-accuracy servo control and is especially suitable for miniaturized applications. PMID:22315530

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

    NASA Astrophysics Data System (ADS)

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

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

  13. Analysis of a hysteresis motor with overexcitation

    SciTech Connect

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

    1982-11-01

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

  14. Case study of Chilled Water Loop Low Delta-T Fault Diagnosis 

    E-print Network

    Wang, L.; Meline, K.; Watt, J.

    2014-01-01

    Case study of Chilled Water Loop Low ?T Fault Diagnosis Lei Wang1, Ph.D., P.E. Ken Meline2, P.E. James Watt1, P.E. Bahman Yazdani1 P.E., David E. Claridge1, Ph.D., P.E 1Energy Systems Laboratory, Texas A&M Engineering Experiment Station...Case Study of Chilled Water Loop Low DT Fault Diagnosis Presented by Lei Wang Ph.D. P.E. Energy Systems Laboratory, Texas A&M University System Sep. 15, 2014 Energy Systems Laboratory p. 1 ESL-IC-14-09-12a Proceedings of the 14th International...

  15. Flexible pivot mount eliminates friction and hysteresis

    NASA Technical Reports Server (NTRS)

    Highman, C. O.

    1970-01-01

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

  16. Design of hysteresis circuits using differential amplifiers

    NASA Technical Reports Server (NTRS)

    Cooke, W. A.

    1971-01-01

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

  17. 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.

  18. Hysteresis loss in vector Preisach models

    Microsoft Academic Search

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

    2010-01-01

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

  19. Hysteresis regimes in fuel burning processes

    Microsoft Academic Search

    S. P. Bardakhanov; A. V. Potapkin

    1999-01-01

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

  20. Hysteresis and transition in swirling nonpremixed flames

    Microsoft Academic Search

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

    2009-01-01

    Strongly swirling nonpremixed flames are known to exhibit a hysteresis when transiting from an attached long, sooty, yellow flame to a short lifted blue flame, and vice versa. The upward transition (by increasing the air and fuel flow rates) corresponds to a vortex breakdown, i.e. an abrupt change from an attached swirling flame (unidirectional or with a weak bluff-body recirculation),

  1. Role of hysteresis in stomatal aperture dynamics

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  2. Torque meter aids study of hysteresis motor rings

    NASA Technical Reports Server (NTRS)

    Cole, M.

    1967-01-01

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

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

    E-print Network

    Jerome, Joseph W.

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

  4. A physical model for hysteresis curves of ferroelectric ceramics

    Microsoft Academic Search

    G. Arlt

    1996-01-01

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

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

    Microsoft Academic Search

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

    1995-01-01

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

  6. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

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

  7. A Domain Wall Model for Hysteresis in Ferroelastic Materials

    E-print Network

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

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

    SciTech Connect

    Xie, H.; Regnier, S. [Institute of Intelligent System and Robotics, University of Pierre and Marie Curie/CNRS UMR 7222, 4 Place Jussieu, 75005 Paris (France); Rakotondrabe, M. [Department of Automatic Control and Micro-Mechatronic Systems, FEMTO-ST Institute, CNRS UMR 6174-UFC/ENSMM/UTBM, 24, Rue Alain Savary, 25000 Besancon (France)

    2009-04-15

    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.

  9. Loop Representations

    E-print Network

    B. Bruegmann

    1993-12-02

    The loop representation plays an important role in canonical quantum gravity because loop variables allow a natural treatment of the constraints. In these lectures we give an elementary introduction to (i) the relevant history of loops in knot theory and gauge theory, (ii) the loop representation of Maxwell theory, and (iii) the loop representation of canonical quantum gravity. (Based on lectures given at the 117. Heraeus Seminar, Bad Honnef, Sept. 1993)

  10. Low-hysteresis materials for magnetic refrigeration: Gd/sub 1-x/Er/sub x/Al/sub 2/

    SciTech Connect

    Zimm, C.B.; Barclay, J.A.; Johanson, W.R.

    1983-01-01

    The series of ferromagnetic intermetallics Gd/sub 1-x/Er/sub x/Al/sub 2/ are candidate working materials for magnetic refrigeration because of their large moment, small anisotropy, and the fact that their Curie temperatures span the range 14 K to 164 K. We have measured the magnitude of the magnetic hysteresis as a function of temperature from 4 K to T/sub c/ for polycrystalline samples of these materials via ac magnetic susceptibility and magnetization hysteresis loops. We found, as expected, virtually no hysteresis in GdAl/sub 2/, and more surprisingly, less than 3000 A/m hysteresis in ErAl/sub 2/, and 2 x 10/sup 4/ A/m in Gd/sub 0/ /sub 5/Er/sub 0/ /sub 5/Al/sub 2/. Moreover, the hysteresis in Gd/sub 0/ /sub 5/Er/sub 0/ /sub 5/Al/sub 2/ was less than or equal to 100 A/m for T - T/sub c/ < 20 K.

  11. 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.

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

    SciTech Connect

    Gao Fei; Zhao Shuxia; Li Xiaosong; Wang Younian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2010-10-15

    An experimental investigation of the hysteresis during the E (capacitive coupling) and H mode (inductive coupling) transitions at various matching situation in argon inductively coupled plasma is reported. At high pressure, the results show two hysteresis loops involved the plasma density, applied power, and forward power, as well as the electrical parameters in the discharge circuit, when the series capacitance is cycled. The measured electron density versus applied power shows that the hysteresis loop shrinks with the decrease of the matching capacitance, and the same trend is discovered on the input current, voltage, and phase angle. In addition, for the case of small capacitance, the current (or voltage) jumps to a low value when the discharge passes through the E to H mode transition regime. Contrarily, for the case of large capacitance, the current jumps to a high value while the voltage is almost constant. The evolution characteristics of the plasma and circuit parameters observed imply that the nonlinear behavior of the matching situation may be one of the determined factors for hysteresis.

  13. Stability of dithered non-linear systems with backlash or hysteresis

    NASA Technical Reports Server (NTRS)

    Desoer, C. A.; Shahruz, S. M.

    1986-01-01

    A study is conducted of the effect of dither on the nonlinear element of a single-input single-outout feedback system. Nonlinearities are considered with memory (backlash, hysteresis), in the feedforward loop; a dither of a given amplitude is injected at the input of the nonlinearity. The nonlinearity is followed by a linear element with low-pass characteristic. The stability of the dithered system and an approximate equivalent system (in which the nonlinearity is a smooth function) are compared. Conditions on the input and on the dither frequency are obtained so that the approximate-system stability guarantees that of the given hysteretic system.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Sharma, Auditya; Andreanov, Alexei; Müller, Markus

    2014-10-01

    We study avalanches along the hysteresis loop of long-range interacting spin glasses with continuous XY symmetry, which serves as a toy model of granular superconductors with long-range and frustrated Josephson couplings. We identify sudden jumps in the T =0 configurations of the XY phases as an external field is increased. They are initiated by the softest mode of the inverse susceptibility matrix becoming unstable, which induces an avalanche of phase updates (or spin alignments). We analyze the statistics of these events and study the correlation between the nonlinear avalanches and the soft mode that initiates them. We find that the avalanches follow the directions of a small fraction of the softest modes of the inverse susceptibility matrix, similarly as was found in avalanches in jammed systems. In contrast to the similar Ising spin glass (Sherrington-Kirkpatrick) studied previously, we find that avalanches are not distributed with a scale-free power law but rather have a typical size which scales with the system size. We also observe that the Hessians of the spin-glass minima are not part of standard random matrix ensembles as the lowest eigenvector has a fractal support.

  17. 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.

  18. 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

  19. Structural phase transformation and hysteresis behavior of Cu-Zn ferrites

    NASA Astrophysics Data System (ADS)

    Maria, Kazi Hanium; Choudhury, Shamima; Hakim, Mohammad Abdul

    2013-06-01

    A series of Cu1- x Zn x Fe2O4 ferrite (with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) compositions were synthesized using the standard solid-state reaction technique. X-ray diffraction was used to study the structure of the above investigated samples. The theoretical and experimental lattice parameters ( a th and a exp) were calculated for each composition. A significant decrease in density and subsequent increase in porosity were observed with increasing Zn content. Curie temperature, T C, has been determined from the temperature dependence of permeability and found to decrease with increasing Zn content. The anomaly observed in the temperature dependence of permeability was attributed to the existence of two structural phases: cubic phase and tetragonal phase. Low-field hysteresis measurements have been performed using a B- H loop trace from which hysteresis parameters have been determined. Coercivity and hysteresis loss were estimated with different Zn contents.

  20. Scalar and vector hysteresis simulations using HysterSoft

    NASA Astrophysics Data System (ADS)

    Dimian, M.; Andrei, P.

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  2. Mechano-electric optoisolator transducer with hysteresis

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  3. Hysteresis prediction inside magnetic shields and application

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  4. Hysteresis prediction inside magnetic shields and application.

    PubMed

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

    2014-07-01

    We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60??T. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission. PMID:25085183

  5. 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.

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

    SciTech Connect

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

    2006-07-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    In this paper, we analyze two types of hysteresis in spin crossover molecular magnets compounds in the framework of the First Order Reversal Curve (FORC) method. The switching between the two stable states in these compounds is accompanied by hysteresis phenomena if the intermolecular interactions are higher than a threshold. We have measured the static thermal hysteresis (TH) and the kinetic light induced thermal hysteresis (LITH) major loops and FORCs for the polycrystalline Fe(II) spin crossover compound [Fe1-xZnx(bbtr)3](ClO4)2 (bbtr = 1,4-di(1,2,3-triazol-1-yl)butane), either in a pure state (x = 0) or doped with Zn ions (x = 0.33) considering different sweeping rates. Here, we use this method not only to infer the domains distribution but also to disentangle between kinetic and static components of the LITH and to estimate the changes in the intermolecular interactions introduced by dopants. We also determined the qualitative relationship between FORC distributions measured for TH and LITH.

  8. NATURE BIOTECHNOLOGY VOLUME 30 NUMBER 6 JUNE 2012 513 P E R S P E C T I V E

    E-print Network

    Fierer, Noah

    NATURE BIOTECHNOLOGY VOLUME 30 NUMBER 6 JUNE 2012 513 P E R S P E C T I V E Metagenomics holds in comparability of data will facilitate the study of biotechnologically relevant processes, such as bioprospecting, to date, played only a small role in biotechnological research, with the majority of novel developments

  9. Coupled magnetoelastic theory of magnetic and magnetostrictive hysteresis

    Microsoft Academic Search

    Martin J. Sablik; David C. Jiles

    1993-01-01

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

  10. A Free Energy Model for Hysteresis in Ferroelectric Materials

    E-print Network

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

  11. Impact of relative permeability hysteresis on geological CO2 storage

    Microsoft Academic Search

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

    2006-01-01

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

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

    E-print Network

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

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

    Microsoft Academic Search

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

    2008-01-01

    We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can

  14. International Workshop on Multi-Rate Processes and Hysteresis

    Microsoft Academic Search

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

    2008-01-01

    We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can

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

    Microsoft Academic Search

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

    1992-01-01

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

  16. 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

  17. Determining CoTE for Concrete Elizabeth Lukefahr, P.E., Ryan Barborak, P.E., Gary Peterson, and Andy Naranjo, P.E.,

    E-print Network

    to collect the displacement data, but due to the configuration of the frame and water bath, this left, and Andy Naranjo, P.E., Texas DOT INTRODUCTION Early-age distress, primarily shallow spalling, in continuously reinforced concrete pavements (CRCP) in Texas has been a problem for several decades. This type

  18. Assessing catchment connectivity using hysteretic loops

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia; Masselink, Rens; Goni, Mikel; Campo, Miguel Angel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel

    2015-04-01

    Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within landscapes. This information is valuable for land managers to be able to take appropriate action at the correct place. Hysteresis between sediment and water discharge can give important information about the sources , pathways and conditions of sediment that arrives at the outlet of a catchment. "Hysteresis" happens when the sediment concentration associated with a certain flow rate 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. Many types of hysteretic loops have been described as well as the cause for the shape of the loop, mainly describing the origin of the sediments. In this study, several measures to objectively classify hysteretic loops in an automated way were developed. These were consecutively used to classify several hundreds of loops from several agricultural catchments in Northern Spain. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz "principal", Op, and Oskotz "woodland", Ow). La Tejería and Latxaga watersheds, located in the Central Western part of Navarre, are roughly similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (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. Furthermore, antecedent conditions and event characteristics were analysed. The loops were compared quantitatively and qualitatively between catchments for similar events and within the catchments for events with different characteristics.

  19. e x p e r i m e n t a l h a p t i c s Why another haptic rendering

    E-print Network

    Salisbury, Kenneth

    1 e x p e r i m e n t a l h a p t i c s Why another haptic rendering algorithm? · Potential fields as possible to the actual device position, without penetrating the plane · Haptically, we could render in the form of the avatar position rendered at the last iteration ­ Note: The haptics loop runs faster than

  20. 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.

  1. Phasing Loops 

    E-print Network

    Guinski, Rodrigo 1980-

    2012-11-30

    This work consists of a set of eight vector graphics animations exploring phasing loops, intended to be displayed on televisions and monitors, for home use or exhibition in art galleries as Generative Cinema installations. ...

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

    Microsoft Academic Search

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

    2006-01-01

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

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

    E-print Network

    Smyth, Katherine M.

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    E-print Network

    Tuffin, Bruno

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

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

    E-print Network

    Loureiro, Andre Oliveira Ferreira

    2013-07-03

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

  7. On the question of hysteresis in Hall magnetohydrodynamic reconnection

    SciTech Connect

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

    2010-11-15

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

  8. 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.

  9. Controlling hysteresis in superconducting constrictions with a resistive shunt

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    Microsoft Academic Search

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

    2011-01-01

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

  11. 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.

  12. HYSTERESIS OF BACKFLOW IMPRINTED IN COLLIMATED JETS

    SciTech Connect

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

    2010-01-20

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

  13. Hysteresis of Backflow Imprinted in Collimated Jets

    E-print Network

    Mizuta, Akira; Nagakura, Hiroki

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wasilewski, P.

    1974-01-01

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

  15. 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.

  16. Adhesion hysteresis and friction at nanometer and micrometer lengths

    SciTech Connect

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lo, C. C. H.

    2012-04-01

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

  18. Loop-to-loop coupling.

    SciTech Connect

    Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald

    2012-05-01

    This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

  19. Hydrological annual hysteresis: functional signature for assessing the consistency of catchment conceptual models?

    NASA Astrophysics Data System (ADS)

    Fovet, Ophelie; Laurent, Ruiz; Markus, Hrachowitz; Chantal, Gascuel-Odoux

    2015-04-01

    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. In this study, the annual hysteric patterns observed between stream flow and water storage is analysed both in the saturated and unsaturated zones of the hillslope and the riparian zone of a headwater catchment in French Brittany (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, saturated, and unsaturated storages led 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, integration of a riparian component led to overall improved hysteretic signatures, even if some misrepresentation remained. Such systems-like approach is likely to improve model selection.

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

    SciTech Connect

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

    2012-01-01

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

  1. THE NEW ZEALAND PA P E R FORUM

    E-print Network

    Hickman, Mark

    THE NEW ZEALAND PA P E R FORUM PAPER IS THE NATURAL CHOICE FOR THE ENVIRONMENT, ECONOMY & SOCIETY neutral. New Zealanders recycle 73%1 of all paper (amongst the world's leaders). ECONOMY Forestry and wood processing represents 4% of New Zealand's GDP and is our 3rd largest export sector. Recycled paper

  2. Formative Assessment Probes: Using the P-E-O Technique

    ERIC Educational Resources Information Center

    Keeley, Page

    2013-01-01

    This article describes how observing whether objects sink or float in water using the P-E-O (Predict, Explain, and Observe) technique is an elementary precursor to developing explanations in later grades that involve an understanding of density and buoyancy. Beginning as early as preschool, elementary students engage in activities that encourage…

  3. Jorge A. Arroyo, P.E. Texas Water Development Board

    E-print Network

    Yang, Zong-Liang

    Jorge A. Arroyo, P.E. Texas Water Development Board Presenting to Center for Integrated Earth System Science Austin, Texas February 13, 2012 Texas Water Development Board Innovative Water Technologies Programs #12;Texas Water Development Board To provide leadership, planning, financial assistance

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

    PubMed

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

    2012-06-19

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  8. Observations of Hysteresis Among Indicators of Solar Activity

    NASA Astrophysics Data System (ADS)

    Bachmann, K. T.; Ranganath, A.

    1999-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Yücesoy, Burcu; Berker, A. Nihat

    2008-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. 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.

  12. Large-scale separation and hysteresis in cascades

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  13. Low hysteresis FeMn-based top spin valve.

    PubMed

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

    2012-09-01

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

  14. 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.

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

    E-print Network

    Smyth, Katherine Marie

    2010-01-01

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

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

    E-print Network

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

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

    E-print Network

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

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

    E-print Network

    Petta, Jason

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

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

    NSDL National Science Digital Library

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

    2009-04-14

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

  20. Seasonal variation in phosphorus concentration-discharge hysteresis inferred from high-frequency in situ monitoring

    NASA Astrophysics Data System (ADS)

    Bieroza, M. Z.; Heathwaite, A. L.

    2015-05-01

    High-resolution in situ total phosphorus (TP), total reactive phosphorus (TRP) and turbidity (TURB) time series are presented for a groundwater-dominated agricultural catchment. Meta-analysis of concentration-discharge (c-q) intra-storm signatures for 61 storm events revealed dominant hysteretic patterns with similar frequency of anti-clockwise and clockwise responses; different determinands (TP, TRP, TURB) behaved similarly. We found that the c-q loop direction is controlled by seasonally variable flow discharge and temperature whereas the magnitude is controlled by antecedent rainfall. Anti-clockwise storm events showed lower flow discharge and higher temperature compared to clockwise events. Hydrological controls were more important for clockwise events and TP and TURB responses, whereas in-stream biogeochemical controls were important for anti-clockwise storm events and TRP responses. Based on the best predictors of the direction of the hysteresis loops, we calibrated and validated a simple fuzzy logic inference model (FIS) to determine likely direction of the c-q responses. We show that seasonal and inter-storm succession in clockwise and anti-clockwise responses corroborates the transition in P transport from a chemostatic to an episodic regime. Our work delivers new insights for the evidence base on the complexity of phosphorus dynamics. We show the critical value of high-frequency in situ observations in advancing understanding of freshwater biogeochemical processes.

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

    SciTech Connect

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

    1998-06-12

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    Microsoft Academic Search

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

    2004-01-01

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

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

    PubMed

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

    2015-01-01

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

  5. Elastic guides reduce hysteresis effect in Belleville spring package

    NASA Technical Reports Server (NTRS)

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

    1967-01-01

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

  6. Periodic solutions of a forced system with hysteresis.

    NASA Technical Reports Server (NTRS)

    Drew, J. H.

    1972-01-01

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

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

    E-print Network

    Boyer, Edmond

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

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

    E-print Network

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

  9. 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

  10. 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...

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

    Microsoft Academic Search

    Erlend Kristiansen; Karl Erik Zachariassen

    2005-01-01

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

  12. Hysteresis and energy demand: the Announcement Effects and

    E-print Network

    Watson, Andrew

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

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

    Microsoft Academic Search

    Avinash K Dixit

    1989-01-01

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

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

    Microsoft Academic Search

    E. M. Braun; R. F. Holland

    1995-01-01

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

  15. Hysteresis Can Grant Fitness in Stochastically Varying Environment

    PubMed Central

    Friedman, Gary; McCarthy, Stephen; Rachinskii, Dmitrii

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

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

    Microsoft Academic Search

    Hani Vahedi; Abdolreza Sheikholeslami; Mohammad Tavakoli Bina

    2011-01-01

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

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

    Microsoft Academic Search

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

    2005-01-01

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

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

    Microsoft Academic Search

    R. Desmorat; F. Ragueneau; H. Pham

    2007-01-01

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

  20. INSIDE THE HYSTERESIS LOOP: MULTIPLICITY OF INTERNAL STATES IN CONFINED FLUIDS. (R825959)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. Experiments on snap buckling, hysteresis and loop formation in twisted rods

    E-print Network

    van der Heijden, Gert

    experiments involving the bending and twisting of 1 mm diameter nickel-titanium alloy rods, up to 2 m formation, snarling, hockling, welded boundary conditions. Current address: London South Bank University

  2. Factors influencing the elastic moduli, reversible strains and hysteresis loops in martensitic Ti-Nb alloys.

    PubMed

    Bönisch, Matthias; Calin, Mariana; van Humbeeck, Jan; Skrotzki, Werner; Eckert, Jürgen

    2015-03-01

    While the current research focus in the search for biocompatible low-modulus alloys is set on ?-type Ti-based materials, the potential of fully martensitic Ti-based alloys remains largely unexplored. In this work, the influence of composition and pre-straining on the elastic properties of martensitic binary Ti-Nb alloys was studied. Additionally, the phase formation was compared in the as-cast versus the quenched state. The elastic moduli and hardness of the studied martensitic alloys are at a minimum of 16wt.% Nb and peak between 23.5 and 28.5wt.% Nb. The uniaxial deformation behavior of the alloys used is characterized by the absence of distinct yield points. Monotonic and cyclic (hysteretic) loading-unloading experiments were used to study the influence of Nb-content and pre-straining on the elastic moduli. Such experiments were also utilized to assess the recoverable elastic and anelastic deformations as well as hysteretic energy losses. Particular attention has been paid to the separation of non-linear elastic from anelastic strains, which govern the stress and strain limits to which a material can be loaded without deforming it plastically. It is shown that slight pre-straining of martensitic Ti-Nb alloys can lead to considerable reductions in their elastic moduli as well as increases in their total reversible strains. PMID:25579952

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

    PubMed

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

    2014-01-01

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

  4. 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

  5. Model-Based, Closed-Loop Control of PZT Creep for Cavity Ring-Down Spectroscopy.

    PubMed

    McCartt, A D; Ognibene, T J; Bench, G; Turteltaub, K W

    2014-09-01

    Cavity ring-down spectrometers typically employ a PZT stack to modulate the cavity transmission spectrum. While PZTs ease instrument complexity and aid measurement sensitivity, PZT hysteresis hinders the implementation of cavity-length-stabilized, data-acquisition routines. Once the cavity length is stabilized, the cavity's free spectral range imparts extreme linearity and precision to the measured spectrum's wavelength axis. Methods such as frequency-stabilized cavity ring-down spectroscopy have successfully mitigated PZT hysteresis, but their complexity limits commercial applications. Described herein is a single-laser, model-based, closed-loop method for cavity length control. PMID:25395738

  6. Modeling and analysis of hysteresis by harmonic balance method

    NASA Astrophysics Data System (ADS)

    Cheng, Weiying; Saito, Yoshifuru

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Zidari?, Bogomir; Miljavec, Damijan

    2011-01-01

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

  8. 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.

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

    PubMed

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

    2013-06-01

    The swelling and shrinkage of four Picea abies (L. Karst) wood tissue homogeneous samples, of porosity varying between 45% and 78%, is documented with high-resolution synchrotron radiation phase-contrast X-ray tomographic microscopy. We report measurements of the reversible moisture-induced orthotropic swelling/shrinkage strains. Hysteresis is observed when the swelling/shrinkage strain is considered as a function of relative humidity, except for the very high porosity sample. Hysteresis is no longer present when swelling/shrinkage strains are considered versus moisture content, indicating that wood deforms to the same extent whether an amount of moisture is desorbed or adsorbed. Furthermore, swelling anisotropy, in the tangential and radial directions, is found to increase with increasing porosity. The most homogeneous behaviour for a group of cells is found for 30-50 cells, smaller/larger groups having higher orders of variations. PMID:23523731

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

    PubMed

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

    2003-12-01

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

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

    Microsoft Academic Search

    O. E. Buckley; L. W. McKeehan

    1925-01-01

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

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

    PubMed

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

    2000-06-01

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

  13. DR. JOHN H. MATTHYS, P.E. UNDERGRADUATE/GRADUATE UTA STUDENT SCHOLARSHIP

    E-print Network

    Texas at Arlington, University of

    1 DR. JOHN H. MATTHYS, P.E. UNDERGRADUATE/GRADUATE UTA STUDENT SCHOLARSHIP NAME The scholarship shall be designated as the Dr. John H. Matthys, P.E. Undergraduate/Graduate UTA Student Scholarship the scholarship to the Dr. John H. Matthys, P.E. Undergraduate/Graduate UTA Student Scholarship. Since 1976, Dr

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

    E-print Network

    Lakes, Roderic

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

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

    SciTech Connect

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

    2011-06-23

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

  16. Vector hysteresis measurements of not oriented grain SiFe steels by a biaxial hall sensors array

    NASA Astrophysics Data System (ADS)

    Cardelli, E.; Faba, A.

    2014-02-01

    This work discusses the vector measurement of the effective magnetic field inside a not oriented grain SiFe steel sample, taking into account the effect of the demagnetizing field. We propose an array of biaxial Hall sensors, placed up to the sample surface. The calibration of the system and a suitable extrapolation data strongly reduce the uncertainties of the direct measurement and provide an accurate evaluation of the magnetic field inside the material sample. Although the approach proposed can be also used for industrial frequencies, 50-60 Hz or more, the analysis is limited here to the static case, because we are mainly interested in static magnetic measurements. These measurements are especially useful for the vector characterization of soft magnetic materials and, in particular, for the identification and the experimental validation of vector hysteresis models. The experimental analysis presented in the paper deals with commercial not oriented grain SiFe steels. Experimental data about hysteresis loops and static power losses are given.

  17. Synthesis and magnetic properties of platelet ?-Fe 2O 3 particles for medical applications using hysteresis-loss heating

    NASA Astrophysics Data System (ADS)

    Kishimoto, Mikio; Minagawa, Makoto; Yanagihara, Hideto; Oda, Tatsuya; Ohkochi, Nobuhiro; Kita, Eiji

    2012-04-01

    Platelet ?-Fe2O3 particles of particle size less than 100 nm were prepared for medical applications that use the hysteresis-loss heating of ferromagnetic particles. The ?-Fe2O3 particles were obtained through the dehydration, reduction, and oxidation of platelet ?-FeOOH particles, which were synthesized by the precipitation of ferric ions in an alkaline solution containing ethanolamine, and the crystals grown using a hydrothermal treatment. The ?-Fe2O3 particles contained dimples formed by the dehydration of ?-FeOOH particles. The coercive force and the saturation magnetization of the ?-Fe2O3 particles were in the ranges 11.9 to 12.7 kA/m (150 to 160 Oe), and 70 to 72 Am2/kg (70 to 72 emu/g), respectively. The specific loss power of the ?-Fe2O3 particles, estimated from their temperature-raising property measured under a peak magnetic field of 50.9 kA/m (640 Oe) and at a frequency of 117 kHz, was 590 W/g. This value is higher than that of spherical cobalt-containing iron oxide particles having equivalent coercive force and saturation magnetization, reflecting the larger area of the minor hysteresis loop measured under a peak magnetic field of 50.9 kA/m (640 Oe).

  18. NATURAL CONVECTION INPILE LOOP

    Microsoft Academic Search

    Sparrell

    1957-01-01

    A small, natural-convection, NaK-cooled in-pile loop is described. The ; loop has a 3-in. diameter and is 7-ft long. The loop is designed for testing ; small fuel pins at highpower densities. Temperature control in the loop is ; achieved by controlling the coolant flow rate. (T.F.H.);

  19. Quantum loop programs

    E-print Network

    Mingsheng Ying; Yuan Feng

    2007-01-04

    Loop is a powerful program construct in classical computation, but its power is still not exploited fully in quantum computation. The exploitation of such power definitely requires a deep understanding of the mechanism of quantum loop programs. In this paper, we introduce a general scheme of quantum loops and describe its computational process. The notions of termination and almost termination are proposed for quantum loops, and the function computed by a quantum loop is defined. To show their expressive power, quantum loops are applied in describing quantum walks. Necessary and sufficient conditions for termination and almost termination of a general quantum loop on any mixed input state are presented. A quantum loop is said to be (almost) terminating if it (almost) terminates on any input state. We show that a quantum loop is almost terminating if and only if it is uniformly almost terminating. It is observed that a small disturbance either on the unitary transformation in the loop body or on the measurement in the loop guard can make any quantum loop (almost) terminating. Moreover, a representation of the function computed by a quantum loop is given in terms of finite summations of matrices. To illustrate the notions and results obtained in this paper, two simplest classes of quantum loop programs, one qubit quantum loops, and two qubit quantum loops defined by controlled gates, are carefully examined.

  20. The preprocessed doacross loop

    NASA Technical Reports Server (NTRS)

    Saltz, Joel H.; Mirchandaney, Ravi

    1990-01-01

    Dependencies between loop iterations cannot always be characterized during program compilation. Doacross loops typically make use of a-priori knowledge of inter-iteration dependencies to carry out required synchronizations. A type of doacross loop is proposed that allows the scheduling of iterations of a loop among processors without advance knowledge of inter-iteration dependencies. The method proposed for loop iterations requires that parallelizable preprocessing and postprocessing steps be carried out during program execution.

  1. Observations of hysteresis in the annual exchange circulation of a large microtidal estuary

    NASA Astrophysics Data System (ADS)

    Meyers, Steven D.; Wilson, Monica; Luther, Mark. E.

    2015-04-01

    A nonlinear relation between the salinity field and the subtidal exchange circulation in the Tampa Bay estuary is demonstrated using observational data from 1999 to 2011. The data are averaged to form mean monthly climatological values of total freshwater discharge (Q), axial and vertical salinity gradients, and subtidal vertical shear. Well-known steady state solutions indicate that the exchange circulation is linearly proportional to the horizontal salinity gradient, assuming a constant vertical eddy viscosity (Aeff). The exchange flow is found to be multivalued with respect to the horizontal salinity gradient, forming a hysteresis loop in parameter space that passes through three dynamical regimes. Regime I is relatively dry with weak salinity gradients and exchange circulation. Regime II is the wet season (June-September) in which all quantities rapidly increase. In regime III, the exchange flow persists even though Q and the axial salinity gradient are again low. Gradient Richardson numbers and Simpson numbers also form a loop in parameter space with Ri remaining subcritical (turbulent) until the wet season when Ri rises above criticality (weak vertical mixing) where it remains through the end of regime III. The Simpson number is in a narrow range around 0.2, indicating that the horizontal salinity gradient is always a driver of the exchange circulation. The Aeff, estimated from a parameterization of the Richardson number, decreases by almost an order of magnitude from regimes I to II. It remains low during III, indicating that the persistent stratification is insulating the exchange flow from destruction by tidal mixing during this time period.

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

    SciTech Connect

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

    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.}

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

    Microsoft Academic Search

    Y. Zhai; L. Vu-Quoc

    2005-01-01

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

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

    Microsoft Academic Search

    Y. Zhai; L. Vu-Quoc

    2007-01-01

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

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

    Microsoft Academic Search

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

    2011-01-01

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

  6. 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.

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

    Microsoft Academic Search

    S. A. Kulinich; M. Farzaneh

    2009-01-01

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

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

    Microsoft Academic Search

    Huamin Zhu; Kyungsup Kwak

    2006-01-01

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

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

    SciTech Connect

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

    1999-05-01

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

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

    E-print Network

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

  11. 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.

  12. 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.

  13. 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.

  14. Closed-loop analysis of slow adaptation in the control of unknown dynamic hysteretic systems

    Microsoft Academic Search

    James J. Reynolds; Xiaobo Tan; Hassan K. Khalil

    2007-01-01

    This paper continues the analysis of an adaptive control approach for a class of systems represented by an unknown hysteresis nonlinearity preceding unknown linear dynamics. In previous work, the multi-time-scale slow adaptation technique has been shown to produce local, asymptotic parameter convergence in an identification problem. In this paper, the same multi-time-scale slow adaptation technique is applied to the closed-loop

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

    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.

  16. 396 | MAY 2004 | VOLUME 5 www.nature.com/reviews/genetics P E R S P E C T I V E S

    E-print Network

    Bartel, David

    of cell proliferation,cell death and fat metabolism in flies7,8 , neuronal patterning in nematodes9 on components of the RNA-INTERFERENCE (RNAi) machinery,but miRNAs are distinct from the SMALL INTERFERING RNAS (siRNAs) of RNAi in sev- eral respects: miRNAs are generally conserved #12;P E R S P E C T I V E

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

    PubMed

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

    2004-11-01

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

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

    PubMed Central

    Ghatak, Animangsu; Majumder, Abhijit; Kumar, Rajendra

    2008-01-01

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

  19. 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

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

    PubMed

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

    2014-11-01

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

  1. Large melting point hysteresis of Ge nanocrystals embedded inSiO2

    SciTech Connect

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

    2006-05-04

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

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

    Microsoft Academic Search

    R. S. Chandra; I. J. Fialho

    2002-01-01

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

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

    E-print Network

    Sethna, James P.

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

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

    E-print Network

    Sethna, James P.

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

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    E-print Network

    Libbrecht, Kenneth G.

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

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

    Microsoft Academic Search

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

    2000-01-01

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

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

    E-print Network

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

  9. BIOGRAPHICAL DATA OF EUGENE JOSEPH LEBOEUF, PH.D., P.E.

    E-print Network

    Simaan, Nabil

    BIOGRAPHICAL DATA OF EUGENE JOSEPH LEBOEUF, PH.D., P.E. 25 August 2010 CURRENT POSITION: Associate Station B 351831 Nashville, TN 37235 (615) 343-7070 eugene.j.leboeuf@vanderbilt.edu AREAS OF CONCENTRATION-Command Course, 2009 U.S. Army War College, 2010 #12;Biographical Data Eugene J. LeBoeuf, Ph.D., P.E. 2

  10. Hamed Sari-Sarraf, Ph.D., P.E. Page 1 of 6

    E-print Network

    Zhuang, Yu

    Hamed Sari-Sarraf, Ph.D., P.E. Page 1 of 6 AREAS OF EXPERTISE Image processing and pattern in industrial, agricultural, and medical applications EDUCATION Ph.D. in Electrical Engineering The University) - revised the course Principles of Communication Systems (EE3323) #12;Hamed Sari-Sarraf, Ph.D., P.E. Page 2

  11. The thermodynamic origin of hysteresis in insertion batteries.

    PubMed

    Dreyer, Wolfgang; Jamnik, Janko; Guhlke, Clemens; Huth, Robert; Moskon, Joze; Gaberscek, Miran

    2010-05-01

    Lithium batteries are considered the key storage devices for most emerging green technologies such as wind and solar technologies or hybrid and plug-in electric vehicles. Despite the tremendous recent advances in battery research, surprisingly, several fundamental issues of increasing practical importance have not been adequately tackled. One such issue concerns the energy efficiency. Generally, charging of 10(10)-10(17) electrode particles constituting a modern battery electrode proceeds at (much) higher voltages than discharging. Most importantly, the hysteresis between the charge and discharge voltage seems not to disappear as the charging/discharging current vanishes. Herein we present, for the first time, a general explanation of the occurrence of inherent hysteretic behaviour in insertion storage systems containing multiple particles. In a broader sense, the model also predicts the existence of apparent equilibria in battery electrodes, the sequential particle-by-particle charging/discharging mechanism and the disappearance of two-phase behaviour at special experimental conditions. PMID:20383130

  12. The thermodynamic origin of hysteresis in insertion batteries

    NASA Astrophysics Data System (ADS)

    Dreyer, Wolfgang; Jamnik, Janko; Guhlke, Clemens; Huth, Robert; Moškon, Jože; Gaberš?ek, Miran

    2010-05-01

    Lithium batteries are considered the key storage devices for most emerging green technologies such as wind and solar technologies or hybrid and plug-in electric vehicles. Despite the tremendous recent advances in battery research, surprisingly, several fundamental issues of increasing practical importance have not been adequately tackled. One such issue concerns the energy efficiency. Generally, charging of 1010-1017 electrode particles constituting a modern battery electrode proceeds at (much) higher voltages than discharging. Most importantly, the hysteresis between the charge and discharge voltage seems not to disappear as the charging/discharging current vanishes. Herein we present, for the first time, a general explanation of the occurrence of inherent hysteretic behaviour in insertion storage systems containing multiple particles. In a broader sense, the model also predicts the existence of apparent equilibria in battery electrodes, the sequential particle-by-particle charging/discharging mechanism and the disappearance of two-phase behaviour at special experimental conditions.

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

    PubMed

    Hu, Mao-Bin; Wang, Wen-Xu; Jiang, Rui; Wu, Qing-Song; Wu, Yong-Hong

    2007-03-01

    We model information traffic on scale-free networks by introducing the node queue length L proportional to the node degree and its delivering ability C proportional to L . The simulation gives the overall capacity of the traffic system, which is quantified by a phase transition from free flow to congestion. It is found that the maximal capacity of the system results from the case of the local routing coefficient phi slightly larger than zero, and we provide an analysis for the optimal value of phi. In addition, we report for the first time the fundamental diagram of flow against density, in which hysteresis is found, and thus we can classify the traffic flow with four states: free flow, saturated flow, bistable, and jammed. PMID:17500754

  14. 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.

  15. 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

  16. Interactions of Cations with RNA Loop-Loop Complexes

    PubMed Central

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

    2011-01-01

    RNA loop-loop interactions are essential in many biological processes, including initiation of RNA folding into complex tertiary shapes, promotion of dimerization, and viral replication. In this article, we examine interactions of metal ions with five RNA loop-loop complexes of unique biological significance using explicit-solvent molecular-dynamics simulations. These simulations revealed the presence of solvent-accessible tunnels through the major groove of loop-loop interactions that attract and retain cations. Ion dynamics inside these loop-loop complexes were distinctly different from the dynamics of the counterion cloud surrounding RNA and depend on the number of basepairs between loops, purine sequence symmetry, and presence of unpaired nucleotides. The cationic uptake by kissing loops depends on the number of basepairs between loops. It is interesting that loop-loop complexes with similar functionality showed similarities in cation dynamics despite differences in sequence and loop size. PMID:21806941

  17. The extrinsic hysteresis behavior of dilute binary ferrofluids.

    PubMed

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

    2014-10-01

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

  18. Loop Quantum Gravity

    Microsoft Academic Search

    Carlo Rovelli

    1997-01-01

    The problem of finding the quantum theory of the gravitational field, and\\u000athus understanding what is quantum spacetime, is still open. One of the most\\u000aactive of the current approaches is loop quantum gravity. Loop quantum gravity\\u000ais a mathematically well-defined, non-perturbative and background independent\\u000aquantization of general relativity, with its conventional matter couplings. The\\u000aresearch in loop quantum gravity

  19. 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.

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

    E-print Network

    Ranganathan Prabhakar

    2013-01-31

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

  1. Feedback/feedforward control of hysteresis-compensated piezoelectric actuators for high-speed scanning applications

    NASA Astrophysics Data System (ADS)

    Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich

    2015-01-01

    This paper presents the control system design for a piezoelectric actuator (PEA) for a high-speed trajectory scanning application. First nonlinear hysteresis is compensated for by using the Maxwell resistive capacitor model. Then the linear dynamics of the hysteresis-compensated piezoelectric actuator are identified. A proportional plus integral (PI) controller is designed based on the linear system, enhanced by feedforward hysteresis compensation. It is found that the feedback controller does not always improve tracking accuracy. When the input frequency exceeds a certain value, feedforward control only may result in better control performance. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  2. Observational Evidence for Loop-Loop Interaction

    NASA Astrophysics Data System (ADS)

    Guiping, W.; Guangli, H.; Yuhua, T.; Aoao, X.

    2004-01-01

    Through analysis of the data including the hard x-ray(BASTE) microwave(NoRP) and magnetogram(MDI from SOHO) as well as the images of soft x-ray(YHKOH) and EIT(SOHO) on Apr. 151998 solar flare in the active region 8203(N30W12) we found: (1) there are similar quasi period oscillation in the profile of hard x-ray flux (25-5050-100keV) and microwave flux(1GHz) with duration of 85+/-25s every peak includes two sub-peak structures; (2) in the preheat phase of the flare active magnetic field changes apparently and a s-pole spot emerges ; (3) several EIT and soft x-ray loops exist and turn into bright . All of these may suggest that loop-loop interaction indeed exist. Through reconnection the electrons may be accelerated and the hard x-ray and microwave emission take place.

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

    E-print Network

    Wang, Jiandong

    URFHVV x 9DOYH =2+ Fig. 1. The diagram of control loop with valve stiction The identification problem ANR EBONSI project. clearly revealed by plotting the measurable valve output x against the valve input(·) is a control valve, and C(z) is a discrete- time PI controller. The signals y, u, r, v and x are the tank level

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

    Microsoft Academic Search

    Nikolas Geroliminis; Jie Sun

    2011-01-01

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

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

    Microsoft Academic Search

    Nikolas Geroliminis; Jie Sun

    2011-01-01

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

  6. Rapid Total Synthesis of DARPin pE59 and RNase B. a

    E-print Network

    Vinogradov, Alexander A.

    We report the convergent total synthesis of two proteins: DARPin pE59 and Bacillus amyloliquefaciens RNase (Barnase). Leveraging our recently developed fast-flow peptide-synthesis platform, we rapidly explored numerous ...

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

    E-print Network

    Southern California, University of

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

  8. Magnetic structure and hysteresis in hard magnetic nanocrystalline film: Computer simulation

    E-print Network

    Laughlin, David E.

    Magnetic structure and hysteresis in hard magnetic nanocrystalline film: Computer simulation simulations are used to study the effect of crystallographic textures on the magnetic properties of uniaxial nanocrystalline films of hard magnetic materials with arbitrary grain shapes and size distributions

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

    E-print Network

    Friedman, Eby G.

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

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

    E-print Network

    Pinson, Matthew B.

    Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations ...

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Bercovici, D.

    2015-05-01

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

  13. A Vector-Based Trust Model for P2P E-commerce

    Microsoft Academic Search

    Qian Wang; Lifang Wang

    2008-01-01

    Many current P2P trust models are not suitable for P2P e-commerce because the characteristics of P2P e-commerce are not taken into account. In addition, the simple representation of trust cannot be used to accurately gain assess to other peers in the e-commerce community because of the diversity and subjectivity of trust. In order to evaluate the peers for each other,

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

    Microsoft Academic Search

    Bor-Jehng Kang; Chang-Ming Liaw

    2001-01-01

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

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    Microsoft Academic Search

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

    2000-01-01

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

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

    Microsoft Academic Search

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

    2003-01-01

    Carbon nanotube field-effect transistors commonly comprise nanotubes lying on SiO2 surfaces exposed to the ambient environment. It is shown here that the transistors exhibit hysteresis in their electrical characteristics because of charge trapping by water molecules around the nanotubes, including SiO2 surface-bound water proximal to the nanotubes. Hysteresis persists for the transistors in vacuum since the SiO2- bound water does

  18. Hysteresis Affects Approximate Number Discrimination in Young Children

    PubMed Central

    Odic, Darko; Hock, Howard; Halberda, Justin

    2015-01-01

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

  19. Hysteresis of gating underlines sensitization of TRPV3 channels.

    PubMed

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

    2011-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-11-01

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

  1. Does Corneal Hysteresis Correlate with Endothelial Cell Density?

    PubMed Central

    Akova-Budak, Berna; K?vanç, Sertaç Argun

    2015-01-01

    Background Our aim was to determine if there is a correlation between corneal biomechanical properties, endothelial cell count, and corneal pachymetry in healthy corneas. Material/Methods Ninety-two eyes of all subjects underwent complete ocular examination, including intraocular pressure measurement by Goldmann applanation tonometer, objective refraction, and slit-lamp biomicroscopy. Topographic measurements and corneal pachymetry were performed using a Scheimpflug-based (Pentacam, Oculus, Germany) corneal topographer. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with an Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, NY). Endothelial cell count measurement was done using a specular microscope (CellChek, Konan, USA). Results Right eye values of the subjects were taken for the study. The mean CH was 11.5±1.7 mmHg and the mean CRF was 11.2±1.4 mmHg. Mean intraocular pressure was 15.3±2.3 mmHg. The mean endothelial cell count was 2754±205 cells/mm2. No correlation was found between biomechanical properties of cornea and endothelial cell count. There was a significant positive correlation between CH, CRF, and corneal thickness (p<0.001; r=0.79). Conclusions The corneal biomechanical properties significantly correlated with corneal thickness. We found no correlation between CH and CRF with the endothelial cell density in normal subjects. PMID:25994302

  2. 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

  3. Hysteresis of gating underlines sensitization of TRPV3 channels

    PubMed Central

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

    2011-01-01

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

  4. Electrowetting on dielectrics on lubricating fluid based slippery surfaces with negligible hysteresis

    E-print Network

    Jitesh Barman; Arun Kumar Nagarajan; Krishnacharya Khare

    2015-07-09

    Low voltage electrowetting on dielectrics on substrates with thin layer of lubricating fluid to reduce contact angle hysteresis is reported here. On smooth and homogeneous solid surfaces, it is extremely difficult to reduce contact angle hysteresis (contact angle difference between advancing and receding drop volume cycle) and the electrowetting hysteresis (contact angle difference between advancing and receding voltage cycle) below 10{\\deg}. On the other hand, electrowetting hysteresis on rough surfaces can be relatively large (>30{\\deg}) therefore they are of no use for most of the fluidic devices. In the present report we demonstrate that using a thin layer of dielectric lubricating fluid on top of the solid dielectric surface results in drastic reduction in contact angle hysteresis as well as electrowetting hysteresis (surfaces. Subsequently fitting the Lippmann-Young electrowetting equation to the experimental electrowetting data reveal that the dielectric lubricating fluid layer is only responsible for smooth movement of the three phase contact line of the liquid drop and does not affect the effective specific capacitance of the system.

  5. 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.

  6. Hysteresis vs. Graded Responses: The Connections Make All the Difference

    NSDL National Science Digital Library

    Alexander J. Ninfa (Ann Arbor; University of Michigan Medical School REV)

    2004-05-11

    Biological regulatory systems have the potential to provide graded responses to stimuli or may demonstrate switch-like properties. Our understanding of the system design principles controlling these responses is still at a rudimentary stage, and here we consider several recent experimental and theoretical studies that focus on these system design principles. Overt positive feedback loops, or double-negative feedback loops, can produce bistable or multistable systems under the appropriate conditions and can produce graded responses under other conditions. Several design features favor bistability in negatively controlled genetic systems, including a high kinetic order for repression and a large difference in the rates of gene expression in the "on" and "off" states. In positive feedback, a high kinetic order for the activation of gene expression favors bistability. Multistability can result from the combined effects of positive and negative regulators, or from the combined effects of regulators that each demonstrate bistability. Finally, bistability can result in enzymatic systems in which multiple reversible covalent modifications occur, even when no overt feedback loops are present.

  7. Thermal power loops

    NASA Technical Reports Server (NTRS)

    Gottschlich, Joseph M.; Richter, Robert

    1991-01-01

    The concept of a thermal power loop (TPL) to transport thermal power over relatively large distances is presented as an alternative to heat pipes and their derivatives. The TPL is compared to heat pipes, and capillary pumped loops with respect to size, weight, conservation of thermal potential, start-up, and 1-g testing capability. Test results from a proof of feasibility demonstrator at the NASA JPL are discussed. This analysis demonstrates that the development of specific thermal power loops will result in substantial weight and cost savings for many spacecraft.

  8. Large lithium loop experience

    SciTech Connect

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

    1981-10-01

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

  9. Multiprotein DNA looping

    E-print Network

    Jose M. G. Vilar; Leonor Saiz

    2006-06-19

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

  10. A Comparison of Longitudinal and Transverse Cross Sections in the p (e,e'K)/Lambda and p(e,e'K)/Sigma Reactions

    SciTech Connect

    Richard Mohring

    1999-10-01

    Jefferson Lab Experiment E93-018 measured kaon electroproduction in hydrogen in two hyperon channels, p(e, e'K{sup +})Lambda and p(e,e'K{sup +})Sigma{sup 0}. Data in both channels were taken at three (3) different values of the virtual photon transverse linear polarization, epsilon, for each of four (4) values of Q{sup 2} = (0.52, 0.75, 1.00, 2.00) GeV{sup 2}. Cross sections averaged over the azimuthal angle, phi, were extracted (i.e., sigma{sub T} + epsilon sigma{sub L}) at each of these twelve points for each hyperon. Rosenbluth separations were performed to separate the longitudinal and transverse production cross sections.

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

    Microsoft Academic Search

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

    2003-01-01

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

  12. Design Guidance for Reinforced Soil Structures with Marginal Soil Barry R. Christopher, Ph. D., P.E.

    E-print Network

    Zornberg, Jorge G.

    Design Guidance for Reinforced Soil Structures with Marginal Soil Backfills Barry R. Christopher, Ph. D., P.E. Christopher Consultants, Roswell, Georgia, USA .lorge G, Zornberg, Ph. D., P.E. GeoSyntec Consultants, Huntington Beach, California, U.S.A. lames K. Mitchell, Ph,D., P.E. Virginia Polytechnic

  13. Models of flaring loops

    NASA Technical Reports Server (NTRS)

    Emslie, A. Gordon

    1989-01-01

    The somewhat questionable concept of an isolated flare loop and the various physical mechanisms believed to be responsible, to some degree, for energy transport within the loop structure is reviewed. Observational evidence suggests a predominant role for high-energy electrons as an energy transport mechanism, and the consequences of such a scenario is explored in some detail, focusing on radiation signatures in the soft X-ray, hard X-ray, and EUV wavebands, as observed by recent satellite observatories. It is found that the predictions of flare loop models are in fact in excellent agreement with these observations, reinforcing both the notion of the loop as a fundamental component of solar flares and the belief that electron acceleration is an integral part of the flare energy release process.

  14. Cosmic string loop microlensing

    E-print Network

    Chernoff, David F.

    Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a ...

  15. Perspectives On DNA Looping

    Microsoft Academic Search

    Laura Finzi

    DNA looping is a ubiquitous regulatorymechanism which can be involved in DNA transcription, ecombination, repair, etc. Here,\\u000a I will focus on protein-mediated DNA looping as a mechanism of tran-scriptional regulation. Indeed, such topological change\\u000a in DNA is known to repress and\\/or activate many prokaryotic and viral genes [1–4] and is believed to mediate interaction between\\u000a promoters and enhancers as well

  16. Hot giant loop holography

    SciTech Connect

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

    2010-07-15

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

  17. Hot Giant Loop Holography

    E-print Network

    Gianluca Grignani; Joanna L. Karczmarek; Gordon W. Semenoff

    2009-06-03

    We argue that there is a phase transition in the expectation value of the Polyakov loop operator in the large N limit of the high temperature deconfined phase of N=4 Yang-Mills theory on a spatial S^3. It occurs for large completely symmetric representation of the SU(N) symmetry group. We speculate that this transition is reflected in the string theory dual as a critical behavior of the D3-brane duals of large representation loops.

  18. 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.

  19. Explaining Warm Coronal Loops

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros

    2008-01-01

    One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.

  20. Choking loops on surfaces.

    PubMed

    Feng, Xin; Tong, Yiying

    2013-08-01

    We present a method for computing "choking" loops--a set of surface loops that describe the narrowing of the volumes inside/outside of the surface and extend the notion of surface homology and homotopy loops. The intuition behind their definition is that a choking loop represents the region where an offset of the original surface would get pinched. Our generalized loops naturally include the usual 2g handles/tunnels computed based on the topology of the genus-g surface, but also include loops that identify chokepoints or bottlenecks, i.e., boundaries of small membranes separating the inside or outside volume of the surface into disconnected regions. Our definition is based on persistent homology theory, which gives a measure to topological structures, thus providing resilience to noise and a well-defined way to determine topological feature size. More precisely, the persistence computed here is based on the lower star filtration of the interior or exterior 3D domain with the distance field to the surface being the associated 3D Morse function. PMID:23744260

  1. 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.

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

    PubMed

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

    2015-05-21

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

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

    Microsoft Academic Search

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  7. Optimizing Nested Loops with Loop Distribution and Loop Fusion Department of Computer Science and Engineering

    E-print Network

    Sha, Edwin

    be used to reduce the cost of loop bound testing. Loop fusion can also be used to exploit the instruction-level parallelism on the modern high- performance architecture such as VLIW [1, 8]. Loop fusion can enhance the data the instruction-level parallelism and enhance data locality [1, 3, 5, 8]. In [3], Kennedy and McKinley use loop fu

  8. Diamagnetic loop for KSTAR.

    NASA Astrophysics Data System (ADS)

    Bak, Jun-Gyo; Lee, Sang-Gon; Ka, Eun-Mie

    2007-11-01

    Three sets of diamagnetic loop (DL), at different locations, are designed to measure diamagnetic flux during a plasma discharge in the KSTAR machine. Each set consists of two concentric poloidal loops, and it is used for the diamagnetic flux measurement with the compensation of a ripple from to the power supply producing a toroidal field and a pick-up signal from the poloidal field due to the misalignment in the installation. One set is installed on inner wall of the vacuum vessel for the flux measurement at the first plasma in the KSTAR machine. It is located at a toroidal angle in the vacuum vessel, and the gap distance between inner and outer loops is 2 cm. An accurate position measurement of the two loops is done by using a laser tracker system after the installation. The in-situ calibration of the loops is done from the toroidal flux measurement. In the measurement, the electric current of less than 100A is applied to the toroidal field coils. In this work, present status of the DL for the initial measurement in the KSTAR machine will be presented.

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

    NASA Astrophysics Data System (ADS)

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

    1993-02-01

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

  10. 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

  11. 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.

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

    SciTech Connect

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

    1995-04-01

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

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

    PubMed Central

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

    2011-01-01

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

  14. 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.

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

    PubMed

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

    2006-04-01

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

  16. 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.

  17. Permutations and the Loop

    E-print Network

    T. W. Brown

    2008-05-07

    We consider the one-loop two-point function for multi-trace operators in the U(2) sector of \\cN=4 supersymmetric Yang-Mills at finite N. We derive an expression for it in terms of U(N) and S_{n+1} group theory data, where n is the length of the operators. The Clebsch-Gordan operators constructed in 0711.0176, which are diagonal at tree level, only mix at one loop if you can reach the same (n+1)-box Young diagram by adding a single box to each of the n-box Young diagrams of their U(N) representations (which organise their multi-trace structure). Similar results are expected for higher loops and for other sectors of the global symmetry group.

  18. Dynamic Tensile Testing of Kevlar 49 Fabrics ; Barzin Mobasher, Ph.D., P.E.2

    E-print Network

    Mobasher, Barzin

    Dynamic Tensile Testing of Kevlar 49 Fabrics Deju Zhu1 ; Barzin Mobasher, Ph.D., P.E.2 of strain. Kevlar-49 fabrics were tested in tension within a strain-rate range of 25 to 170 sÀ1 using a high nature of Kevlar-49 fabric results in large displacements and shape changes during tests. Noncontacting

  19. Decapsulating Brine Shrimp Eggs 1 Craig Watson and Roy P.E. Yanong2

    E-print Network

    Watson, Craig A.

    FA18 Decapsulating Brine Shrimp Eggs 1 Craig Watson and Roy P.E. Yanong2 1. This document is FA18 Introduction Brine shrimp eggs are used throughout the world as a food for small fish in hatcheries. These eggs as the eggs are exposed to water, the hatching process begins. When hatching brine shrimp eggs, we not only

  20. Manipulation of vortices by magnetic domain walls P. E. Goa,a)

    E-print Network

    Johansen, Tom Henning

    Manipulation of vortices by magnetic domain walls P. E. Goa,a) H. Hauglin, A° . A. F. Olsen, D simultaneous manipulation and imaging of individual vortices in a NbSe2 single crystal. The magnetic field from a Bloch wall in a ferrite garnet film FGF is used to manipulate the vortices. High-resolution magneto

  1. A p p e n d i x J Media, Nutrition,

    E-print Network

    Rau, Don C.

    J­1 j A p p e n d i x J Media, Nutrition, and Physical Activity Resources The following resources these organizations or their positions. #12;Appendix J--Media, Nutrition, and Physical Activity ResourcesJ­2 Nameand Nutrition Focus Calcium Focus Media Info ActionforHealthyKids http://www. actionforhealthykids.org/ (800

  2. Potato Response to ACA on Several Soils K.A. Kelling and P.E. Speth

    E-print Network

    Balser, Teri C.

    Potato Response to ACA on Several Soils K.A. Kelling and P.E. Speth Department of Soil Science University of Wisconsin- Madison #12;ACA ­ Zinc Ammonium acetate ­ 15% N, 17% Zn ­ Recommended rate 0.33-0.67 pt/a ACA Plus ­ 7.5% N, 8.5 %Zn ­ More compatible with wide range of fertilizers ­ Double rate (0

  3. Assessing the Costs Attributed to Project Delay Curtis Beaty, P.E.

    E-print Network

    Assessing the Costs Attributed to Project Delay Curtis Beaty, P.E. David Ellis, Ph.D. Brianne? Who Pays? Is it Reimbursable? Who Pays? Is it Reimbursable? Who Pays?Type of Cost Cost of Project Contractor (opportunity cost) Yes Agency No Public Classifying Costs and Who Pays #12;Project Cost Before

  4. Use of Copper in Marine Aquaculture and Aquarium Roy P. E. Yanong2

    E-print Network

    Watson, Craig A.

    FA165 Use of Copper in Marine Aquaculture and Aquarium Systems1 Roy P. E. Yanong2 1. This document T. Place , Dean Introduction Copper has been used effectively for many years to control algae and fish parasites in freshwater and marine systems. Because copper does not discolor the water

  5. Roger E Husser, Jr., M.S., P.E. Planning, Design & Construction

    E-print Network

    Harms, Kyle E.

    Roger E Husser, Jr., M.S., P.E. Director Planning, Design & Construction Herschel Hoffpauir Associate Director Campus Design & Construction Cliff Gillio Manager Mechanical Engineering Neal Pendleton Project Manager Architect Danielle Welborn Civil Engineer Planning, Design & Construction 1/13/2014 Hari

  6. Use of Antibiotics in Ornamental Fish Aquaculture1 Roy P. E. Yanong2

    E-print Network

    Watson, Craig A.

    Cir 84 Use of Antibiotics in Ornamental Fish Aquaculture1 Roy P. E. Yanong2 1. This document and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension

  7. A Layout-Similarity-Based Approach for Detecting Phishing Pages Angelo P. E. Rosiello

    E-print Network

    Kruegel, Christopher

    A Layout-Similarity-Based Approach for Detecting Phishing Pages Angelo P. E. Rosiello , Engin Kirda@rosiello.org,ferrandi@elet.polimi.it Secure Systems Lab, Technical University Vienna {ek,chris}@seclab.tuwien.ac.at Abstract Phishing is a current social engineering attack that results in online identity theft. In a phishing attack

  8. Dr. Miguel Vlez-Reyes, P.E. Electrical and Computer Engineering Department

    E-print Network

    Gilbes, Fernando

    Dr. Miguel Vélez-Reyes, P.E. Professor Electrical and Computer Engineering Department University.S.E.E. University of Puerto Rico Mayagüez Campus, June 1985 Appointments Department of Electrical and Computer Engineering, University of Puerto Rico Mayagüez Campus, Mayagüez, P.R. Professor July 2000-Present Associate

  9. Rossby Wave Instability and Apparent Phase Speeds in Large Ocean Basins P. E. ISACHSEN

    E-print Network

    LaCasce, Joseph H.

    Rossby Wave Instability and Apparent Phase Speeds in Large Ocean Basins P. E. ISACHSEN Department 30 November 2005, in final form 31 May 2006) ABSTRACT The stability of baroclinic Rossby waves. Introduction Quasigeostrophic (QG) studies suggest that baro- clinic Rossby waves are unstable (Jones 1979

  10. Kathleen M. Smits, Ph.D., P.E. Colorado School of Mines

    E-print Network

    of Colorado Reviewer of papers for: Water Resources Research Vadose Zone Journal Soil Science SocietyKathleen M. Smits, Ph.D., P.E. Colorado School of Mines Dept. of Civil and Environmental Colorado School of Mines (2007-2010) Doctor of Philosophy, Environmental Science and Engineering

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

    NSDL National Science Digital Library

    Megan Sullivan

    2005-07-01

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

  12. Closed loop mechanical ventilation.

    PubMed

    Wysocki, Marc; Jouvet, Philippe; Jaber, Samir

    2014-02-01

    Mechanical ventilation is a sophisticated technique with very narrow therapeutic ranges i.e. highly efficient and able to keep alive the most severe patients, but with considerable side effects and unwanted complications if not properly and timely used. Computerized protocols, closed loop systems, decision support, all terms which need to be defined, may help making mechanical ventilation safer and more efficient. The present paper will provide a short overview on technical and engineering considerations regarding closed loop controlled ventilation as well as tangible clinical evidences supporting the previous statement. PMID:23564277

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    Microsoft Academic Search

    B. K. Bose

    1990-01-01

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

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

    Microsoft Academic Search

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

    2004-01-01

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

  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. Loop Quantum Gravity

    NASA Astrophysics Data System (ADS)

    Rovelli, Carlo

    1998-04-01

    The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. The research in loop quantum gravity forms today a vast area, ranging from mathematical foundations to physical applications. Among the most significative results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume; which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, overcompleteness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. I will provide an overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity.

  1. Loop Quantum Gravity

    NASA Astrophysics Data System (ADS)

    Rovelli, Carlo

    1998-01-01

    The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  2. Automatic loop interchange

    Microsoft Academic Search

    John R. Allen; Ken Kennedy

    1984-01-01

    Parallel and vector machines are becoming increasingly important to many computation intensive applications. Effectively utilizing such architectures, particularly from sequential languages such as Fortran, has demanded increasingly sophisticated compilers. In general, a compiler needs to significantly reorder a program in order to generate code optimal for a specific architecture.Because DO loops typically control the execution of a number of statements,

  3. NETL - Chemical Looping Reactor

    ScienceCinema

    None

    2014-06-26

    NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

  4. Loop heat pipes

    Microsoft Academic Search

    Yu. F. Maydanik

    2005-01-01

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

  5. Closing the Loop Sampler.

    ERIC Educational Resources Information Center

    California Integrated Waste Management Board, Sacramento.

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

  6. NETL - Chemical Looping Reactor

    SciTech Connect

    None

    2013-07-24

    NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

  7. Temporal Resolution [Loop Search

    E-print Network

    Fisher, Michael

    perform the following steps. 1. Transform A into SNF, giving a set of clauses AS. 2. Perform step Logic [TEMPORAL RESOLUTION: LOOP SEARCH] ­ p.2/24 #12;Merged SNF To apply the temporal resolution rule, it is often convenient to combine one or more step clauses. Consequently, a variant on SNF called merged-SNF

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

    PubMed

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

    2011-05-01

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

  9. Three-Loop Static Potential

    SciTech Connect

    Smirnov, Alexander V. [Scientific Research Computing Center, Moscow State University, 119992 Moscow (Russian Federation); Smirnov, Vladimir A. [Skobeltsyn Institute of Nuclear Physics of Moscow State University, 119992 Moscow (Russian Federation); Steinhauser, Matthias [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), D-76128 Karlsruhe (Germany)

    2010-03-19

    We compute the three-loop corrections to the potential of two heavy quarks. In particular, we consider in this Letter the purely gluonic contribution which provides, in combination with our previous fermion corrections, the complete answer at three loops.

  10. Fiber lasers with loop reflectors

    SciTech Connect

    Urquhart, P. (British Telecom Research Laboratories, Martlesham Heath, Ipswich IP5 7RE, U.K. (GB))

    1989-09-01

    The theory of homogeneously broadened four level fiber lasers, which use fiber loops as distributed reflective elements, is examined. Such cavities can be made entirely from rare earth doped fiber. The amplifying characteristics of doped fiber loops are examined. The threshold pump power and the loop reflectivity necessary to optimize the lasing output power from an oscillator formed from two loops in series are predicted.

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

    E-print Network

    Martcheva, Maia

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

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

    Microsoft Academic Search

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

    2005-01-01

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

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

    E-print Network

    Fleming, Andrew J.

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

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

    Microsoft Academic Search

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

    2011-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    E-print Network

    Iyer, Ram Venkataraman

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

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

    Microsoft Academic Search

    A. Bekker; L. C. Brinson

    1998-01-01

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

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

    Microsoft Academic Search

    Miroslav KrstiC; Hsin-Hsiung Wang

    1997-01-01

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

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

    SciTech Connect

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

    2014-09-01

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

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

    PubMed Central

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

    2013-01-01

    Quadrupeds vary their gaits in accordance with their locomotion speed. Such gait transitions exhibit hysteresis. However, the underlying mechanism for this hysteresis remains largely unclear. It has been suggested that gaits correspond to attractors in their dynamics and that gait transitions are non-equilibrium phase transitions that are accompanied by a loss in stability. In the present study, we used a robotic platform to investigate the dynamic stability of gaits and to clarify the hysteresis mechanism in the walk–trot transition of quadrupeds. Specifically, we used a quadruped robot as the body mechanical model and an oscillator network for the nervous system model to emulate dynamic locomotion of a quadruped. Experiments using this robot revealed that dynamic interactions among the robot mechanical system, the oscillator network, and the environment generate walk and trot gaits depending on the locomotion speed. In addition, a walk–trot transition that exhibited hysteresis was observed when the locomotion speed was changed. We evaluated the gait changes of the robot by measuring the locomotion of dogs. Furthermore, we investigated the stability structure during the gait transition of the robot by constructing a potential function from the return map of the relative phase of the legs and clarified the physical characteristics inherent to the gait transition in terms of the dynamics. PMID:23389894

  1. Fractal analysis of soil water hysteresis as influenced by sewage sludge application

    E-print Network

    Perfect, Ed

    Fractal analysis of soil water hysteresis as influenced by sewage sludge application G. Ojeda a,, E) and a loamy sand soil (Typic Haplustalf) from central Catalonia (NE Spain) was investigated using fractal analysis. First, we proposed a composite fractal model that covers both the low and high suction regimes

  2. Materials on the brink: Unprecedented transforming materials www.low-hysteresis.caltech.edu

    E-print Network

    Wuttig (Shenqiang Ren1*) 1 Graduate Student 2 Post-doc · Other/supplemental support + Transitioned #12-change materials Sensing, Actuation, Communications, Energy harvesting and storage But, promise is largely interfaces can reduce hysteresis Nucleation and growth reduces the barrier to structural phase transition

  3. Modulation of the Chopping Frequency in DC Choppers and PWM Inverters Having Current-Hysteresis Controllers

    Microsoft Academic Search

    William McMurray

    1984-01-01

    In a dc chopper converter having its load current regulated by a feedback controller of the fixed hysteresis type, the chopping frequency is shown to depend on the square of the counter EMF of the load. In a pulsewidth modulated (PWM) inverter, the counter EMF is modulated at the output frequency, so the chopping frequency is modulated at twice the

  4. Effects of flux and torque hysteresis band amplitude in direct torque control of induction machines

    Microsoft Academic Search

    D. Casadei; G. Grandi; G. Serra; A. Tani

    1994-01-01

    Direct torque control of induction machines allows high dynamic performance to be obtained utilising a simple signal processing method. Furthermore, this control technique does not require current regulators so reducing the hardware requirements. In this paper, the influence of the amplitude of flux and torque hysteresis bands on switching frequency, torque and flux ripple, current distortion and drive losses is

  5. High Gain Observer for Induction Motor in Presence of Magnetic Hysteresis , L. Dugard3

    E-print Network

    Paris-Sud XI, Université de

    High Gain Observer for Induction Motor in Presence of Magnetic Hysteresis H. Ouadi1 , F. Giri2 , L in induction motors is considered in this paper. In most previous works, motor observers have been designed using standard models, neglecting the saturation and hysteretic effects in the machine magnetic circuit

  6. Effect of microstructure on the hysteresis performance of force transducers using AISI 4340 steel spring material

    Microsoft Academic Search

    Sinan Fank; Mehmet Demirkol

    2006-01-01

    The application of heat treatments on spring elements of transducers is a very effective method for attaining good performance in force measurements. Heat treatments change the microstructure of the spring material, which plays a major role in the improvement of performance characteristics of force transducers, particularly in terms of hysteresis error. The present study covers attempts at changing the microstructure

  7. Detection of oil slick signatures in SAR images by fusion of hysteresis thresholding responses

    Microsoft Academic Search

    Thomas. F. n. Kanaa; E. Tonye; G. Mercier; V. P. Onana; J. Mvogo Ngono; P. L. Frison; J. P. Rudant; R. Garello

    2003-01-01

    A new method is proposed in this paper to detect oil slick signatures in oceanographic SAR images. This method is based on directional behavioural oil slick in the sea surface. Therefore, directional hysteresis thresholding responses are first computed in order to bring to the fore dark spots, and increase pixels connexity in each Freeman direction. Those responses are then merged

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

    E-print Network

    Visintin, Augusto

    prior to nucleation. Shape memory effects have been ob- served and exploited in some recently developed, for instance. Hysteresis also appears in chemistry, biology, economics, even in experimental psychology, and so memory effects. Rate dependent memory is typically fading, hence scale dependent. Rate independent memory

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

    Microsoft Academic Search

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

    2010-01-01

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

  10. Hysteresis mechanism in pentacene thin-film transistors with poly,,4-vinyl phenol... gate insulator

    E-print Network

    Lee, Jong Duk

    as a cross-linking agent in propylene glycol methyl ether acetate as a solv, the gate charge injection is blocked and the effect of the charges from the channel increases. © 2006 such as the bias- stress effect or hysteresis.7­10 Therefore, understanding the mechanism underlying

  11. Advanced damper with high stiffness and high hysteresis damping based on negative structural stiffness

    E-print Network

    Lakes, Roderic

    Advanced damper with high stiffness and high hysteresis damping based on negative structural online 8 April 2013 Keywords: Damping Stiffness Columns Buckling Uniaxial Compression Experimental techniques Structures a b s t r a c t High structural damping combined with high stiffness is achieved

  12. 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.

  13. Scanning Polyhedra with DO Loops

    Microsoft Academic Search

    Corinne Ancourt; François Irigoin

    1991-01-01

    Supercompilers perform complex program transformations which often result in new loop bounds. This paper shows that, under the usual assumptions in automatic parallelization, most transformations on loop nests can be expressed as affine transformations on integer sets de ned by polyhedra and that the new loop bounds can be computed with algorithms using Fourier's pairwise elimination method although it is

  14. COLD TEST LOOP INTEGRATED TEST LOOP RESULTS

    SciTech Connect

    Abraham, TJ

    2003-10-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. Angular distribution of neutron inverse beta decay, nu¯e+p-->e++n

    Microsoft Academic Search

    P. Vogel; J. F. Beacom

    1999-01-01

    The reaction nu¯e+p-->e++n is very important for low-energy (Enu<~60 MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies is slightly backward. We show that weak magnetism and recoil corrections have a large effect on the angular distribution, making it isotropic at about 15 MeV and slightly forward at higher energies. We also show

  17. A Commodity's Reputation-Based Trust Model of P2P E-Commerce Systems

    Microsoft Academic Search

    Fengyuan Zhu; Guangming Yang; Zhenhuan Tan

    2010-01-01

    In peer-to-peer (P2P) e-commerce systems, the trust mechanisms already proposed always replaced commodity's reputation with peer's reputation, so some peers often try to keep a relatively high peer's trust value while making their profit of doing some dishonest transactions. So, presented CRBT model (commodity's reputation-based trust model)-a novel trust mechanism. By introducing commodity's short-term reputation, commodity's accumulated reputation, peer's short-term

  18. P e d r o R os a s DYNAMIC INFLUENCES OF WIND

    E-print Network

    P e d r o R os a s DYNAMIC INFLUENCES OF WIND POWER ON THE POWER SYSTEM P h D t h e s is S e c t i-91184-16-9 #12;DYNAMIC INFLUENCES OF WIND POWER ON THE POWER SYSTEM By Pedro Rosas Thesis submitted to Ørsted Institute, Risø National Laboratory & Brazilian Wind Energy Centre Denmark, March 2003 iii #12;iv #12

  19. Getting Your Loops Straight

    NSDL National Science Digital Library

    L. Bryan Ray (AAAS; )

    2008-10-17

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

  20. Loop Quantum Cosmology

    NASA Astrophysics Data System (ADS)

    Bojowald, Martin

    2005-12-01

    Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new ki! nds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.

  1. Loop Quantum Cosmology

    NASA Astrophysics Data System (ADS)

    Bojowald, Martin

    2008-07-01

    Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.

  2. Cosmic string loop microlensing

    NASA Astrophysics Data System (ADS)

    Bloomfield, Jolyon K.; Chernoff, David F.

    2014-06-01

    Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.

  3. Hot Holographic Giant Loop

    NASA Astrophysics Data System (ADS)

    Grignani, G.; Karczmarek, J. L.; Semenoff, G. W.

    2013-12-01

    We consider the Polyakov loop operator in finite temperature planar N = 4 supersymmetric Yang-Mills theory defined on a spatial S3 and in representations where the number of boxes in the Young Tableau k is large and scales so that kN remains finite in the large N limit. We review the argument that, in the de-confined phase of the gauge theory, and for symmetric representations with row Young tableau, there is a quantum phase transition in the expectation value of the Polyakov loop operator which occurs as the size of the representation is increased beyond a critical value of kN. We also argue that for completely antisymmetric representations with column tableau, there is no such phase transition. The AdS/CFT dual of such large representation loops are thought to be probe D-branes with k units of fundamental string charge dissolved in their world-volumes. Our results for both symmetric and antisymmetric representations are consistent with what is known about these branes on the thermal AdS black hole background.

  4. Chemical Looping Combustion Kinetics

    SciTech Connect

    Edward Eyring; Gabor Konya

    2009-03-31

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

  5. RUNNING HEAD: teacher expectancy effects in P.E. The Influence of Teacher Expectations on Students Achievement in Physical Education

    E-print Network

    Paris-Sud XI, Université de

    RUNNING HEAD: teacher expectancy effects in P.E. The Influence of Teacher Expectations on Students 32, 5 (2002) 591-607" #12;Teacher expectancy effects in P.E. 2 2 ABSTRACT The main purpose of this study was to explore the relation between teacher expectations and student achievement in physical

  6. Interrelationships Among Curriculum and Instruction Variables and Learning Outcomes in Project P.E.A.C.E.

    ERIC Educational Resources Information Center

    Bennett, Roger V.

    The paper focuses on development and implementation of the curriculum phase of an urban environmental studies program entitled Project Environmental Action Community Education (P.E.A.C.E.) The curriculum model developed for P.E.A.C.E. was based on the premises that it should be created by relevant consumer groups as well as educators,…

  7. Coupled dual loop absorption heat pump

    DOEpatents

    Sarkisian, Paul H. (Watertown, MA); Reimann, Robert C. (Lafayette, NY); Biermann, Wendell J. (Fayetteville, NY)

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  8. Two loop divergences studied with one loop constrained differential renormalization

    SciTech Connect

    Seijas, Cesar [Departamento de Fi sica de Parti culas, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain)]. E-mail: cesar@fpaxp1.usc.es

    2007-08-15

    In the context of differential renormalization, using constrained differential renormalization rules at one-loop, we show how to obtain concrete results in two-loop calculations without making use of Ward identities. In order to do that, we obtain a list of integrals with overlapping divergences compatible with CDR that can be applied to various two-loop background field calculations. As an example, we obtain the two-loop coefficient of the beta function of QED, SuperQED and Yang-Mills theory.

  9. The Gulf Loop Current

    NSDL National Science Digital Library

    Pam Stryker

    2010-01-01

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

  10. Optical parametric loop mirror

    NASA Astrophysics Data System (ADS)

    Mori, K.; Morioka, T.; Saruwatari, M.

    1995-06-01

    A novel configuration for four-wave mixing (FWM) is proposed that offers the remarkable feature of inherently separating the FWM wave from the input pump and signal waves and suppressing their background amplified stimulated emission without optical filtering. In the proposed configuration, an optical parametric loop mirror, two counterpropagating FWM waves generated in a Sagnac interferometer interfere with a relative phase difference that is introduced deliberately. FWM frequency-conversion experiments in a polarization-maintaining fiber achieved more than 35 dB of input-wave suppression against the FWM wave.

  11. Closing the loop.

    PubMed

    Dassau, E; Atlas, E; Phillip, M

    2011-02-01

    Closed-loop algorithms can be found in every aspect of everyday modern life. Automation and control are used constantly to provide safety and to improve quality of life. Closed-loop systems and algorithms can be found in home appliances, automobiles, aviation and more. Can one imagine nowadays driving a car without ABS, cruise control or even anti-sliding control? Similar principles of automation and control can be used in the management of diabetes mellitus (DM). The idea of an algorithmic/technological way to control glycaemia is not new and has been researched for more than four decades. However, recent improvements in both glucose-sensing technology and insulin delivery together with advanced control and systems engineering made this dream of an artificial pancreas possible. The artificial pancreas may be the next big step in the treatment of DM since the use of insulin analogues. An artificial pancreas can be described as internal or external devices that use continuous glucose measurements to automatically manage exogenous insulin delivery with or without other hormones in an attempt to restore glucose regulation in individuals with DM using a control algorithm. This device as described can be internal or external; can use different types of control algorithms with bi-hormonal or uni-hormonal design; and can utilise different ways to administer them. The different designs and implementations have transitioned recently from in silico simulations to clinical evaluation stage with practical applications in mind. This may mark the beginning of a new era in diabetes management with the introduction of semi-closed-loop systems that can prevent or minimise nocturnal hypoglycaemia, to hybrid systems that will manage blood glucose (BG) levels with minimal user intervention to finally fully automated systems that will take the user out of the loop. More and more clinical trials will be needed for the artificial pancreas to become a reality but initial encouraging results are proof that we are on the right track. We attempted to select recent publications that will present these current achievements in the quest for the artificial pancreas and that will inspire others to continue to progress this field of research. PMID:21323809

  12. O.P.E. and Power Corrections to the QCD coupling constant

    NASA Astrophysics Data System (ADS)

    Boucaud, Ph.; De Soto, F.; Donini, A.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Moutarde, H.; Pène, O.; Rodríquez-Quintero, J.

    2003-01-01

    Lattice data seems to show that power corrections should be convoked to describe appropriately the transition of the QCD coupling constant running from U.V. to I.R. domains. Those power corrections for the Landau-gauge MOM coupling constant in a pure Yang-Mills theory ( Nf = 0) are analysed in terms of Operator Product Expansion (O.P.E.) of two- and three-point Green functions, the gluon condensate < A 2 > emerging from this study. The semi-classical picture given by instantons can be also used to look for into the nature of the power corrections and gluon condensate.

  13. 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 (dq?). Finally, simulation results using Matlab/Simulink are given to validate the proposed control.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  16. 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.

  17. An implicit method for the nonlinear modelling and simulation of piezoceramic actuators displaying hysteresis

    NASA Technical Reports Server (NTRS)

    Leigh, Timothy D.; Zimmerman, David C.

    1991-01-01

    Experiments have shown that piezoceramic materials display a nonlinear relationship between the applied electric field and the actuation strain. This relationship also displays a substantial hysteresis upon reversal of the applied field. In this paper, piezoceramic actuator models are incorporated into the structural equations of motion to arrive at a set of nonlinear actively controlled structural equations of motion. A new implicit algorithm for determining the time history of the actively controlled structure is presented. The algorithm employs the trapezoidal rule for stepping the equations forward in time. The algorithm is compared to an explicit algorithm and is shown to provide greater numerical accuracy. In addition, the numerical stability and convergence characteristics are presented via example. The new algorithm displays convergence and stability properties that are comparable to the standard trapezoidal rule used for dynamic systems without hysteresis.

  18. Hysteresis loss analysis of soft magnetic materials under direct current bias conditions

    NASA Astrophysics Data System (ADS)

    Turgut, Zafer; Kosai, Hiroyuki; Bixel, Tyler; Scofield, James; Semiatin, S. Lee; Horwath, John

    2015-05-01

    Direct current bias related hysteresis loss characteristics of three commercially available magnetic materials: (1) an iron based Metglas tape core, (2) a Sendust powder core, and (3) a Mn-Zn based ferrite in both un-gapped and gapped configurations were studied. The measurements are conducted for a fixed external field Hext, a fixed flux swing (?B), and a fixed maximum forward magnetization (Bmax) as a function of the external bias field. In all the measurements, a direct correlation is found between permeability and measured loss values as a function of dc bias field. Increased hysteresis losses are measured in the magnetization rotation region in which classical domain theory predicts minimal losses. The observed trends are discussed within the frame work of classical domain theory.

  19. Magnetocaloric effect in the low hysteresis Ni-Mn-In metamagnetic shape-memory Heusler alloy

    NASA Astrophysics Data System (ADS)

    Stern-Taulats, Enric; Castillo-Villa, Pedro O.; Mañosa, Lluís; Frontera, Carlos; Pramanick, Sabyasachi; Majumdar, Subham; Planes, Antoni

    2014-05-01

    We have studied magnetocaloric properties of a Ni-Mn-In metamagnetic shape-memory alloy especially designed in order to display low thermal hysteresis. Magnetization and calorimetric measurements under a magnetic field have been used in order to determine isothermal magnetic field-induced entropy changes. Results obtained indirectly from magnetization data, quasi-directly from isofield calorimetric measurements, and directly from isothermal calorimetric runs are systematic and agree well with each other. We have analyzed the reproducibility of magnetocaloric properties with cycling from direct isothermal calorimetric measurements. Due to low thermal hysteresis, we have found that about 80% of the transition entropy change, ?St ? 25 J/kg K, can be reversibly induced under successive application and removal of a field of 6 T.

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

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

  1. Design for Fermilab main injector magnet ramps which account for hysteresis

    SciTech Connect

    Brown, B.C.; Bhat, C.M.; Harding, D.J.; Martin, P.S.; Wu, G.

    1997-05-01

    Although the dominant fields in accelerator electromagnets are proportional to the excitation current, precise control of accelerator parameters requires a detailed understanding of the fields in Main Injector magnets including contribution from eddy currents, magnet saturation, and hysteresis. Operation for decelerating beam makes such considerations particularly significant. Analysis of magnet measurements and design of control system software is presented. Field saturation and its effects on low field hysteresis are accounted for in specifying the field ramps for dipole, quadrupole and sextupole magnets. Some simplifying assumptions are made which are accepted as limitations on the required ramp sequences. Specifications are provided for relating desired field ramps to required current ramps for the momentum, tune, and chromaticity control.

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

    PubMed

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

    2015-02-27

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

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

    SciTech Connect

    Zhang, Yang [ORNL; Faraone, Antonio [National Institute of Standards and Technology (NIST); Kamitakahara, William [ORNL; Liu, Kao-Hsiang [National Taiwan University; Mou, Chung-Yuan [National Taiwan University; Leao, Juscelino B [ORNL; Chang, Sung C [ORNL; Chen, Sow-hsin H [ORNL

    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.

  4. 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.

  5. Kinematics of Electrons in The Volume of a Planar Vacuum Diode in Regime of Saturation. Parameters of Hysteresis

    E-print Network

    Dimitar G. Stoyanov

    2014-12-19

    The kinematics laws of electrons motion in the volume of a planar vacuum diode running in regime of current saturation are used. The characteristics of diode hysteresis in the conditions of S-figurative instability are got and analyzed.

  6. Kinematics of Electrons in The Volume of a Planar Vacuum Diode in Regime of Saturation. Parameters of Hysteresis

    E-print Network

    Stoyanov, Dimitar G

    2015-01-01

    The kinematics laws of electrons motion in the volume of a planar vacuum diode running in regime of current saturation are used. The characteristics of diode hysteresis in the conditions of S-figurative instability are got and analyzed.

  7. The double loop mattress suture

    PubMed Central

    Biddlestone, John; Samuel, Madan; Creagh, Terry; Ahmad, Tariq

    2014-01-01

    An interrupted stitch type with favorable tissue characteristics will reduce local wound complications. We describe a novel high-strength, low-tension repair for the interrupted closure of skin, cartilage, and muscle, the double loop mattress stitch, and compare it experimentally with other interrupted closure methods. The performance of the double loop mattress technique in porcine cartilage and skeletal muscle is compared with the simple, mattress, and loop mattress interrupted sutures in both a novel porcine loading chamber and mechanical model. Wound apposition is assessed by electron microscopy. The performance of the double loop mattress in vivo was confirmed using a series of 805 pediatric laparotomies/laparoscopies. The double loop mattress suture is 3.5 times stronger than the loop mattress in muscle and 1.6 times stronger in cartilage (p ? 0.001). Additionally, the double loop mattress reduces tissue tension by 66% compared with just 53% for the loop mattress (p ? 0.001). Wound gapping is equal, and wound eversion appears significantly improved (p ? 0.001) compared with the loop mattress in vitro. In vivo, the double loop mattress performs as well as the loop mattress and significantly better than the mattress stitch in assessments of wound eversion and dehiscence. There were no episodes of stitch extrusion in our series of patients. The mechanical advantage of its intrinsic pulley arrangement gives the double loop mattress its favorable properties. Wound dehiscence is reduced because this stitch type is stronger and exerts less tension on the tissue than the mattress stitch. We advocate the use of this novel stitch wherever a high-strength, low-tension repair is required. These properties will enhance wound repair, and its application will be useful to surgeons of all disciplines. PMID:24698436

  8. Unplugging of Prolene IOL Loops

    Microsoft Academic Search

    Fridbert Jonasson; John M. S. McConnell

    1987-01-01

    From end 1981 until early 1984, 415 Severin-type lenses were implanted in our two centres. In 10 instances i.e. 2.4%, we experienced unplugging of the anterior 12 o’clock positioned loop, apparently a result of the loop being held with the insertions forceps during insertion. The unplugging of the loop possibly affected the visual outcome in one instance.

  9. Accelerating the loop expansion

    SciTech Connect

    Ingermanson, R.

    1986-07-29

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

  10. Resultants and loop closure

    NASA Astrophysics Data System (ADS)

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

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

  11. Comparative study on stress–strain hysteresis response of SAC solder joints under thermal cycles

    Microsoft Academic Search

    Alireza Shirazi; Ahmad Varvani-Farahani; Hua Lu

    2008-01-01

    The present study attempts to evaluate the stress-strain hysteresis responses of SAC solder joints in Resistor and FleXBGA144\\u000a packages subjected to thermal cyclic loading using several constitutive models. The total deformation of the solder material\\u000a consists of elastic, rate-independent plastic and rate-dependent creep components. The constitutive models discussed in this\\u000a study each weighted elastic, plastic and creep deformations differently. At

  12. Hysteresis-Current-Controlled Buck Converter Suitable for Li-Ion Battery Charger

    Microsoft Academic Search

    Fong-Cheng Yang; Chih-Chiang Chen; Jiann-Jong Chen; Yuh-Shyan Hwang; Wen-Ta Lee

    2006-01-01

    A new hysteresis-current-controlled (HCC) buck converter suitable for Li-ion battery charger is presented in this paper. The technique adopted in this charger is constant current\\/constant voltage dual mode, which is decided by the value of internal resistance of Li-ion battery. This technique will degrade the damage of Li-ion battery and improve the power efficiency of charger. The Li-ion battery charger

  13. Magnetic properties modeling of soft magnetic composite materials using two-dimensional vector hybrid hysteresis model

    NASA Astrophysics Data System (ADS)

    Li, Dandan; Liu, Fugui; Li, Yongjian; Zhao, Zhigang; Zhang, Changgeng; Yang, Qingxin

    2014-05-01

    A 2-D vector hybrid hysteresis model for a soft magnetic composite (SMC) material is established, which is combined with classical Preisach model and Stoner-Wohlfarth (S-W) model. The rotational magnetic properties of SMC materials were studied using the vector model, and the computed results were compared with the experimental measurement. It is shown that the vector hybrid model can effectively simulate the rotational magnetic properties under low magnetization fields.

  14. Hysteresis, feed-back mechanisms, and time-delays in the solar wind -magnetosphere energy circulation.

    NASA Astrophysics Data System (ADS)

    Koskinen, Hannu; Palmroth, Minna; Pulkkinen, Tuija

    We discuss various explanations for the asymmetric behaviour of the solar wind energy input to the magnetosphere when the IMF is rotated through due southward orientation, which has been revealed by global solar wind -magnetosphere -ionosphere simulations. When the V Bz electric field first increases and then starts to decrease, the energy input remains higher than it was for the corresponding IMF clock angle before the southward orientation. It appears that to reduce the energy input rate requires reaching smaller V Bz than is the case when increasing the input. Phenomenologically this is analogous to the hysteresis cycle in ferromagnetic media. As the magnetosphere is a complicated non-linear feedback system with several sources of inertia and time delays, the hysteresis itself may not be a big surprise, but we do not yet understand what it is telling us of the magnetospheric dynamics. While the proximate explanation may be possible to find in the local plasma and magnetic field properties at the magnetopause, the ultimate reason for the hysteresis and its quantitative aspects may well lie in the inertia and feed-back mechanisms in the coupling of the outer magnetospheric boundaries to the inner parts of the system, e.g., in the coupling of the Region 1 currents through the polar ionosphere, in the Region 1 -Region 2 -partial ring current system, in the connection of the polar cusp to the noon sector auroral zone, in the changing properties of plasma sheet due to the changing solar wind driver, or in any combination of two or more of these. Experimental confirmation, direct or indirect, of the hysteresis should be considered as one of the great challenges in magnetospheric plasma physics.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1992-02-01

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

  17. 4D-CT lung motion estimation with deformable registration: quantification of motion nonlinearity and hysteresis.

    PubMed

    Boldea, Vlad; Sharp, Gregory C; Jiang, Steve B; Sarrut, David

    2008-03-01

    In this article, our goal is twofold. First, we propose and compare two methods which process deformable registration to estimate patient specific lung and tumor displacements and deformation during free breathing from four-dimensional computed tomography (4D-CT) data. Second, we propose techniques to quantify the physiological parameters of motion nonlinearity and hysteresis. A Fréchet distance-based criterion is introduced to measure the motion hysteresis. Experiments were conducted with 4D-CT data of five patients treated in radiotherapy for non-small cell lung cancer. The accuracy of deformation fields assessed against expert-selected landmarks was found to be within image voxel tolerance. The second method gave slightly better results in terms of accuracy and consistency, although the differences were not statistically significant between the two methods. Lung motion nonlinearity and hysteresis are patient specific, and vary across regions within the lung during respiration. For all patients, motion between end-exhale and end-inhale was well approximated with a straight line trajectory for the majority of lung points. Hysteresis was found to be globally correlated with trajectory length. The main limitation to the proposed method is that intensity-based deformable registration is dependent on image quality and image resolution. Another limitation is the absence of gold standard which makes the validation of the computed motion difficult. However, the proposed tools provide patient specific motion information which, in radiotherapy for example, can ease the definition of precise internal margins. In the future, the integration of physiological information from multiple patients could help to create a general lung atlas with different clinical applications. PMID:18404936

  18. Sensitivity of sulfate direct climate forcing to the hysteresis of particle phase transitions

    Microsoft Academic Search

    Jun Wang; Daniel J. Jacob; Scot T. Martin

    2008-01-01

    particles and the associated hysteresis. The model also treats the extent of sulfate neutralization by ammonia. For the anthropogenic sulfate, the base case simulation finds that solid particles contribute 41% of the global burden, 26% of the clear-sky optical thickness, 31% of the clear-sky SDCF, and 37% of the full-sky SDCF, a trend that reflects the correlation of solid particles

  19. Finite-set model predictive control of a flying capacitor converter with hysteresis voltage balancing

    Microsoft Academic Search

    Peter Stolze; Peter Landsmann; Ralph Kennel; Toit Mouton

    2011-01-01

    This paper presents a predictive strategy for current control of a three-phase flying capacitor converter. Future values of the load current and flying capacitor voltages are predicted with discrete-time system models. An offline solution for obtaining the best one of the 19 possible voltage vectors is combined with a hysteresis-based voltage balancing algorithm which makes use of the redundancy of

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

    SciTech Connect

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

    2001-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  2. Hydrological and Hysteresis Response of Open Lined Channels in Small Urban Residential Catchments in Singapore

    Microsoft Academic Search

    W. Lee

    2005-01-01

    Two small urban residential catchments, namely Jurong West (JW) (1 ha) and Ang Mo Kio (AMK) (0.6 ha) in Singapore have been selected as sites to investigate hysteresis patterns and hydrological responses from catchments' pervious surfaces and different types of impervious, namely directly connected impervious areas (DCIA) and non-directly connected impervious areas (Non-DCIA)during rain events. Results from February 2005 till

  3. Does unemployment hysteresis falsify the natural rate hypothesis? a meta-regression analysis

    Microsoft Academic Search

    T. D. Stanley

    2004-01-01

    Abstract.?A quantitative survey of 24 studies containing 99 national estimates of unemployment persistence reinstates unemployment hysteresis as a viable falsifying hypothesis to the natural rate hypothesis. Empirical evidence to the contrary may be attributed to small-sample, misspecification and publication biases. Larger estimates of unemployment persistence are produced by models that use more information (t?=?9.03; P?

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

    Microsoft Academic Search

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

    2003-01-01

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

  5. 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.

  6. Hysteresis Modeling of the Porous Nitinol Delivery System, Designed and Fabricated By Sls Method

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.

    At report, we presented a common design and theoretical modelling scheme for a porous scaffold from nitinol with a shape memory effect (SME), fabricated by the selective laser sintering (SLS) process. The operation of the SME fluidic MEMS involves such physical process as heat transfer, phase transformation with temperature hysteresis, stress-strain and electrical resistance variations accompanying the phase transformation. This model can be used for an estimation of drug delivery system (DDS) route during a porous volume changing.

  7. Rheological–dynamical analogy: Prediction of damping parameters of hysteresis damper

    Microsoft Academic Search

    Dragan D. Milašinovi?

    2007-01-01

    This research aims to predict the damping parameters of hysteresis damper based on an analytical rheological–dynamical (RDA) visco-elasto-plastic solution of one-dimensional longitudinal continuous vibrations of a bar. A visco-elasto-plastic bar or damper is an energy dissipation device. An attempt is made to estimate quantitatively the influence of material physical parameters of materials on the damping ratio in both the linear

  8. 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.

  9. Dynamic hysteresis dispersion scaling of ferroelectric Nd-substituted Bi4Ti3O12 thin films

    Microsoft Academic Search

    J-M Liu; B Pan; H Yu; S T Zhang

    2004-01-01

    The dynamics of ferroelectric hysteresis for Nd-substituted Bi4Ti3O12 thin films as a function of frequency and amplitude of time-varying external electric field is measured utilizing a Sawyer–Tower (ST) circuit. The frequency ranges from 1 to 106 Hz and the amplitude range is 101–400 kV cm?1. Given a fixed field amplitude E0, the hysteresis area A first grows and then decays

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

    PubMed Central

    Magalhães, Júlia M. C. S.

    1997-01-01

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

  11. pE-DB: a database of structural ensembles of intrinsically disordered and of unfolded proteins

    PubMed Central

    Varadi, Mihaly; Kosol, Simone; Lebrun, Pierre; Valentini, Erica; Blackledge, Martin; Dunker, A. Keith; Felli, Isabella C.; Forman-Kay, Julie D.; Kriwacki, Richard W.; Pierattelli, Roberta; Sussman, Joel; Svergun, Dmitri I.; Uversky, Vladimir N.; Vendruscolo, Michele; Wishart, David; Wright, Peter E.; Tompa, Peter

    2014-01-01

    The goal of pE-DB (http://pedb.vib.be) is to serve as an openly accessible database for the deposition of structural ensembles of intrinsically disordered proteins (IDPs) and of denatured proteins based on nuclear magnetic resonance spectroscopy, small-angle X-ray scattering and other data measured in solution. Owing to the inherent flexibility of IDPs, solution techniques are particularly appropriate for characterizing their biophysical properties, and structural ensembles in agreement with these data provide a convenient tool for describing the underlying conformational sampling. Database entries consist of (i) primary experimental data with descriptions of the acquisition methods and algorithms used for the ensemble calculations, and (ii) the structural ensembles consistent with these data, provided as a set of models in a Protein Data Bank format. PE-DB is open for submissions from the community, and is intended as a forum for disseminating the structural ensembles and the methodologies used to generate them. While the need to represent the IDP structures is clear, methods for determining and evaluating the structural ensembles are still evolving. The availability of the pE-DB database is expected to promote the development of new modeling methods and leads to a better understanding of how function arises from disordered states. PMID:24174539

  12. 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.

  13. 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.

  14. Modeling of Voltage Hysteresis and Relaxation for HEV NiMH Battery

    NASA Astrophysics Data System (ADS)

    Ota, Yutaka; Hashimoto, Yoshihiro

    SOC (State of Charge) estimation based battery management is essential for HEV (Hybrid Electric Vehicle) applications. SOC can be estimated by the relationship between OCV (Open Circuit Voltage) and SOC, which is based on Nernst equation, in combination with coulomb counting. However voltage hysteresis and relaxation make the measurement of OCV difficult. Measured OCV after charge (discharge) is higher (lower) than estimated OCV by Nernst equation, and is slowly relaxed with time constant from few minutes to few hours. In this paper, to express voltage hysteresis and relaxation, three layers model concerning Nickel active materials is proposed. A voltage gap between surface and inside of Nickel active materials is introduced, and voltage hysteresis is modeled as surface partial battery decides OCV of the whole battery. Voltage relaxation is also expressed as equalization between surface layer and relaxation layer with higher internal resistance. The statical and dynamical behavior of proposed model is confirmed through the experiments of 7.2V 6.5Ah NiMH battery module.

  15. 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

  16. 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

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Hergt, Rudolf; Dutz, Silvio; Röder, Michael

    2008-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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